Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/memory.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 */
7
8/*
9 * demand-loading started 01.12.91 - seems it is high on the list of
10 * things wanted, and it should be easy to implement. - Linus
11 */
12
13/*
14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 * pages started 02.12.91, seems to work. - Linus.
16 *
17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 * would have taken more than the 6M I have free, but it worked well as
19 * far as I could see.
20 *
21 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22 */
23
24/*
25 * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 * thought has to go into this. Oh, well..
27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 * Found it. Everything seems to work now.
29 * 20.12.91 - Ok, making the swap-device changeable like the root.
30 */
31
32/*
33 * 05.04.94 - Multi-page memory management added for v1.1.
34 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 *
36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 * (Gerhard.Wichert@pdb.siemens.de)
38 *
39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40 */
41
42#include <linux/kernel_stat.h>
43#include <linux/mm.h>
44#include <linux/mm_inline.h>
45#include <linux/sched/mm.h>
46#include <linux/sched/coredump.h>
47#include <linux/sched/numa_balancing.h>
48#include <linux/sched/task.h>
49#include <linux/hugetlb.h>
50#include <linux/mman.h>
51#include <linux/swap.h>
52#include <linux/highmem.h>
53#include <linux/pagemap.h>
54#include <linux/memremap.h>
55#include <linux/kmsan.h>
56#include <linux/ksm.h>
57#include <linux/rmap.h>
58#include <linux/export.h>
59#include <linux/delayacct.h>
60#include <linux/init.h>
61#include <linux/pfn_t.h>
62#include <linux/writeback.h>
63#include <linux/memcontrol.h>
64#include <linux/mmu_notifier.h>
65#include <linux/swapops.h>
66#include <linux/elf.h>
67#include <linux/gfp.h>
68#include <linux/migrate.h>
69#include <linux/string.h>
70#include <linux/memory-tiers.h>
71#include <linux/debugfs.h>
72#include <linux/userfaultfd_k.h>
73#include <linux/dax.h>
74#include <linux/oom.h>
75#include <linux/numa.h>
76#include <linux/perf_event.h>
77#include <linux/ptrace.h>
78#include <linux/vmalloc.h>
79#include <linux/sched/sysctl.h>
80
81#include <trace/events/kmem.h>
82
83#include <asm/io.h>
84#include <asm/mmu_context.h>
85#include <asm/pgalloc.h>
86#include <linux/uaccess.h>
87#include <asm/tlb.h>
88#include <asm/tlbflush.h>
89
90#include "pgalloc-track.h"
91#include "internal.h"
92#include "swap.h"
93
94#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
95#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
96#endif
97
98#ifndef CONFIG_NUMA
99unsigned long max_mapnr;
100EXPORT_SYMBOL(max_mapnr);
101
102struct page *mem_map;
103EXPORT_SYMBOL(mem_map);
104#endif
105
106static vm_fault_t do_fault(struct vm_fault *vmf);
107
108/*
109 * A number of key systems in x86 including ioremap() rely on the assumption
110 * that high_memory defines the upper bound on direct map memory, then end
111 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
112 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
113 * and ZONE_HIGHMEM.
114 */
115void *high_memory;
116EXPORT_SYMBOL(high_memory);
117
118/*
119 * Randomize the address space (stacks, mmaps, brk, etc.).
120 *
121 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
122 * as ancient (libc5 based) binaries can segfault. )
123 */
124int randomize_va_space __read_mostly =
125#ifdef CONFIG_COMPAT_BRK
126 1;
127#else
128 2;
129#endif
130
131#ifndef arch_wants_old_prefaulted_pte
132static inline bool arch_wants_old_prefaulted_pte(void)
133{
134 /*
135 * Transitioning a PTE from 'old' to 'young' can be expensive on
136 * some architectures, even if it's performed in hardware. By
137 * default, "false" means prefaulted entries will be 'young'.
138 */
139 return false;
140}
141#endif
142
143static int __init disable_randmaps(char *s)
144{
145 randomize_va_space = 0;
146 return 1;
147}
148__setup("norandmaps", disable_randmaps);
149
150unsigned long zero_pfn __read_mostly;
151EXPORT_SYMBOL(zero_pfn);
152
153unsigned long highest_memmap_pfn __read_mostly;
154
155/*
156 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
157 */
158static int __init init_zero_pfn(void)
159{
160 zero_pfn = page_to_pfn(ZERO_PAGE(0));
161 return 0;
162}
163early_initcall(init_zero_pfn);
164
165void mm_trace_rss_stat(struct mm_struct *mm, int member)
166{
167 trace_rss_stat(mm, member);
168}
169
170/*
171 * Note: this doesn't free the actual pages themselves. That
172 * has been handled earlier when unmapping all the memory regions.
173 */
174static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
175 unsigned long addr)
176{
177 pgtable_t token = pmd_pgtable(*pmd);
178 pmd_clear(pmd);
179 pte_free_tlb(tlb, token, addr);
180 mm_dec_nr_ptes(tlb->mm);
181}
182
183static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
184 unsigned long addr, unsigned long end,
185 unsigned long floor, unsigned long ceiling)
186{
187 pmd_t *pmd;
188 unsigned long next;
189 unsigned long start;
190
191 start = addr;
192 pmd = pmd_offset(pud, addr);
193 do {
194 next = pmd_addr_end(addr, end);
195 if (pmd_none_or_clear_bad(pmd))
196 continue;
197 free_pte_range(tlb, pmd, addr);
198 } while (pmd++, addr = next, addr != end);
199
200 start &= PUD_MASK;
201 if (start < floor)
202 return;
203 if (ceiling) {
204 ceiling &= PUD_MASK;
205 if (!ceiling)
206 return;
207 }
208 if (end - 1 > ceiling - 1)
209 return;
210
211 pmd = pmd_offset(pud, start);
212 pud_clear(pud);
213 pmd_free_tlb(tlb, pmd, start);
214 mm_dec_nr_pmds(tlb->mm);
215}
216
217static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
218 unsigned long addr, unsigned long end,
219 unsigned long floor, unsigned long ceiling)
220{
221 pud_t *pud;
222 unsigned long next;
223 unsigned long start;
224
225 start = addr;
226 pud = pud_offset(p4d, addr);
227 do {
228 next = pud_addr_end(addr, end);
229 if (pud_none_or_clear_bad(pud))
230 continue;
231 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
232 } while (pud++, addr = next, addr != end);
233
234 start &= P4D_MASK;
235 if (start < floor)
236 return;
237 if (ceiling) {
238 ceiling &= P4D_MASK;
239 if (!ceiling)
240 return;
241 }
242 if (end - 1 > ceiling - 1)
243 return;
244
245 pud = pud_offset(p4d, start);
246 p4d_clear(p4d);
247 pud_free_tlb(tlb, pud, start);
248 mm_dec_nr_puds(tlb->mm);
249}
250
251static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
252 unsigned long addr, unsigned long end,
253 unsigned long floor, unsigned long ceiling)
254{
255 p4d_t *p4d;
256 unsigned long next;
257 unsigned long start;
258
259 start = addr;
260 p4d = p4d_offset(pgd, addr);
261 do {
262 next = p4d_addr_end(addr, end);
263 if (p4d_none_or_clear_bad(p4d))
264 continue;
265 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
266 } while (p4d++, addr = next, addr != end);
267
268 start &= PGDIR_MASK;
269 if (start < floor)
270 return;
271 if (ceiling) {
272 ceiling &= PGDIR_MASK;
273 if (!ceiling)
274 return;
275 }
276 if (end - 1 > ceiling - 1)
277 return;
278
279 p4d = p4d_offset(pgd, start);
280 pgd_clear(pgd);
281 p4d_free_tlb(tlb, p4d, start);
282}
283
284/*
285 * This function frees user-level page tables of a process.
286 */
287void free_pgd_range(struct mmu_gather *tlb,
288 unsigned long addr, unsigned long end,
289 unsigned long floor, unsigned long ceiling)
290{
291 pgd_t *pgd;
292 unsigned long next;
293
294 /*
295 * The next few lines have given us lots of grief...
296 *
297 * Why are we testing PMD* at this top level? Because often
298 * there will be no work to do at all, and we'd prefer not to
299 * go all the way down to the bottom just to discover that.
300 *
301 * Why all these "- 1"s? Because 0 represents both the bottom
302 * of the address space and the top of it (using -1 for the
303 * top wouldn't help much: the masks would do the wrong thing).
304 * The rule is that addr 0 and floor 0 refer to the bottom of
305 * the address space, but end 0 and ceiling 0 refer to the top
306 * Comparisons need to use "end - 1" and "ceiling - 1" (though
307 * that end 0 case should be mythical).
308 *
309 * Wherever addr is brought up or ceiling brought down, we must
310 * be careful to reject "the opposite 0" before it confuses the
311 * subsequent tests. But what about where end is brought down
312 * by PMD_SIZE below? no, end can't go down to 0 there.
313 *
314 * Whereas we round start (addr) and ceiling down, by different
315 * masks at different levels, in order to test whether a table
316 * now has no other vmas using it, so can be freed, we don't
317 * bother to round floor or end up - the tests don't need that.
318 */
319
320 addr &= PMD_MASK;
321 if (addr < floor) {
322 addr += PMD_SIZE;
323 if (!addr)
324 return;
325 }
326 if (ceiling) {
327 ceiling &= PMD_MASK;
328 if (!ceiling)
329 return;
330 }
331 if (end - 1 > ceiling - 1)
332 end -= PMD_SIZE;
333 if (addr > end - 1)
334 return;
335 /*
336 * We add page table cache pages with PAGE_SIZE,
337 * (see pte_free_tlb()), flush the tlb if we need
338 */
339 tlb_change_page_size(tlb, PAGE_SIZE);
340 pgd = pgd_offset(tlb->mm, addr);
341 do {
342 next = pgd_addr_end(addr, end);
343 if (pgd_none_or_clear_bad(pgd))
344 continue;
345 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
346 } while (pgd++, addr = next, addr != end);
347}
348
349void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
350 struct vm_area_struct *vma, unsigned long floor,
351 unsigned long ceiling)
352{
353 MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
354
355 do {
356 unsigned long addr = vma->vm_start;
357 struct vm_area_struct *next;
358
359 /*
360 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
361 * be 0. This will underflow and is okay.
362 */
363 next = mas_find(&mas, ceiling - 1);
364
365 /*
366 * Hide vma from rmap and truncate_pagecache before freeing
367 * pgtables
368 */
369 unlink_anon_vmas(vma);
370 unlink_file_vma(vma);
371
372 if (is_vm_hugetlb_page(vma)) {
373 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
374 floor, next ? next->vm_start : ceiling);
375 } else {
376 /*
377 * Optimization: gather nearby vmas into one call down
378 */
379 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
380 && !is_vm_hugetlb_page(next)) {
381 vma = next;
382 next = mas_find(&mas, ceiling - 1);
383 unlink_anon_vmas(vma);
384 unlink_file_vma(vma);
385 }
386 free_pgd_range(tlb, addr, vma->vm_end,
387 floor, next ? next->vm_start : ceiling);
388 }
389 vma = next;
390 } while (vma);
391}
392
393void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
394{
395 spinlock_t *ptl = pmd_lock(mm, pmd);
396
397 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
398 mm_inc_nr_ptes(mm);
399 /*
400 * Ensure all pte setup (eg. pte page lock and page clearing) are
401 * visible before the pte is made visible to other CPUs by being
402 * put into page tables.
403 *
404 * The other side of the story is the pointer chasing in the page
405 * table walking code (when walking the page table without locking;
406 * ie. most of the time). Fortunately, these data accesses consist
407 * of a chain of data-dependent loads, meaning most CPUs (alpha
408 * being the notable exception) will already guarantee loads are
409 * seen in-order. See the alpha page table accessors for the
410 * smp_rmb() barriers in page table walking code.
411 */
412 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
413 pmd_populate(mm, pmd, *pte);
414 *pte = NULL;
415 }
416 spin_unlock(ptl);
417}
418
419int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
420{
421 pgtable_t new = pte_alloc_one(mm);
422 if (!new)
423 return -ENOMEM;
424
425 pmd_install(mm, pmd, &new);
426 if (new)
427 pte_free(mm, new);
428 return 0;
429}
430
431int __pte_alloc_kernel(pmd_t *pmd)
432{
433 pte_t *new = pte_alloc_one_kernel(&init_mm);
434 if (!new)
435 return -ENOMEM;
436
437 spin_lock(&init_mm.page_table_lock);
438 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
439 smp_wmb(); /* See comment in pmd_install() */
440 pmd_populate_kernel(&init_mm, pmd, new);
441 new = NULL;
442 }
443 spin_unlock(&init_mm.page_table_lock);
444 if (new)
445 pte_free_kernel(&init_mm, new);
446 return 0;
447}
448
449static inline void init_rss_vec(int *rss)
450{
451 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
452}
453
454static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
455{
456 int i;
457
458 if (current->mm == mm)
459 sync_mm_rss(mm);
460 for (i = 0; i < NR_MM_COUNTERS; i++)
461 if (rss[i])
462 add_mm_counter(mm, i, rss[i]);
463}
464
465/*
466 * This function is called to print an error when a bad pte
467 * is found. For example, we might have a PFN-mapped pte in
468 * a region that doesn't allow it.
469 *
470 * The calling function must still handle the error.
471 */
472static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
473 pte_t pte, struct page *page)
474{
475 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
476 p4d_t *p4d = p4d_offset(pgd, addr);
477 pud_t *pud = pud_offset(p4d, addr);
478 pmd_t *pmd = pmd_offset(pud, addr);
479 struct address_space *mapping;
480 pgoff_t index;
481 static unsigned long resume;
482 static unsigned long nr_shown;
483 static unsigned long nr_unshown;
484
485 /*
486 * Allow a burst of 60 reports, then keep quiet for that minute;
487 * or allow a steady drip of one report per second.
488 */
489 if (nr_shown == 60) {
490 if (time_before(jiffies, resume)) {
491 nr_unshown++;
492 return;
493 }
494 if (nr_unshown) {
495 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
496 nr_unshown);
497 nr_unshown = 0;
498 }
499 nr_shown = 0;
500 }
501 if (nr_shown++ == 0)
502 resume = jiffies + 60 * HZ;
503
504 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
505 index = linear_page_index(vma, addr);
506
507 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
508 current->comm,
509 (long long)pte_val(pte), (long long)pmd_val(*pmd));
510 if (page)
511 dump_page(page, "bad pte");
512 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
513 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
514 pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
515 vma->vm_file,
516 vma->vm_ops ? vma->vm_ops->fault : NULL,
517 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
518 mapping ? mapping->a_ops->read_folio : NULL);
519 dump_stack();
520 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
521}
522
523/*
524 * vm_normal_page -- This function gets the "struct page" associated with a pte.
525 *
526 * "Special" mappings do not wish to be associated with a "struct page" (either
527 * it doesn't exist, or it exists but they don't want to touch it). In this
528 * case, NULL is returned here. "Normal" mappings do have a struct page.
529 *
530 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
531 * pte bit, in which case this function is trivial. Secondly, an architecture
532 * may not have a spare pte bit, which requires a more complicated scheme,
533 * described below.
534 *
535 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
536 * special mapping (even if there are underlying and valid "struct pages").
537 * COWed pages of a VM_PFNMAP are always normal.
538 *
539 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
540 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
541 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
542 * mapping will always honor the rule
543 *
544 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
545 *
546 * And for normal mappings this is false.
547 *
548 * This restricts such mappings to be a linear translation from virtual address
549 * to pfn. To get around this restriction, we allow arbitrary mappings so long
550 * as the vma is not a COW mapping; in that case, we know that all ptes are
551 * special (because none can have been COWed).
552 *
553 *
554 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
555 *
556 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
557 * page" backing, however the difference is that _all_ pages with a struct
558 * page (that is, those where pfn_valid is true) are refcounted and considered
559 * normal pages by the VM. The disadvantage is that pages are refcounted
560 * (which can be slower and simply not an option for some PFNMAP users). The
561 * advantage is that we don't have to follow the strict linearity rule of
562 * PFNMAP mappings in order to support COWable mappings.
563 *
564 */
565struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
566 pte_t pte)
567{
568 unsigned long pfn = pte_pfn(pte);
569
570 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
571 if (likely(!pte_special(pte)))
572 goto check_pfn;
573 if (vma->vm_ops && vma->vm_ops->find_special_page)
574 return vma->vm_ops->find_special_page(vma, addr);
575 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
576 return NULL;
577 if (is_zero_pfn(pfn))
578 return NULL;
579 if (pte_devmap(pte))
580 /*
581 * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
582 * and will have refcounts incremented on their struct pages
583 * when they are inserted into PTEs, thus they are safe to
584 * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
585 * do not have refcounts. Example of legacy ZONE_DEVICE is
586 * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
587 */
588 return NULL;
589
590 print_bad_pte(vma, addr, pte, NULL);
591 return NULL;
592 }
593
594 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
595
596 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
597 if (vma->vm_flags & VM_MIXEDMAP) {
598 if (!pfn_valid(pfn))
599 return NULL;
600 goto out;
601 } else {
602 unsigned long off;
603 off = (addr - vma->vm_start) >> PAGE_SHIFT;
604 if (pfn == vma->vm_pgoff + off)
605 return NULL;
606 if (!is_cow_mapping(vma->vm_flags))
607 return NULL;
608 }
609 }
610
611 if (is_zero_pfn(pfn))
612 return NULL;
613
614check_pfn:
615 if (unlikely(pfn > highest_memmap_pfn)) {
616 print_bad_pte(vma, addr, pte, NULL);
617 return NULL;
618 }
619
620 /*
621 * NOTE! We still have PageReserved() pages in the page tables.
622 * eg. VDSO mappings can cause them to exist.
623 */
624out:
625 return pfn_to_page(pfn);
626}
627
628#ifdef CONFIG_TRANSPARENT_HUGEPAGE
629struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
630 pmd_t pmd)
631{
632 unsigned long pfn = pmd_pfn(pmd);
633
634 /*
635 * There is no pmd_special() but there may be special pmds, e.g.
636 * in a direct-access (dax) mapping, so let's just replicate the
637 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
638 */
639 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
640 if (vma->vm_flags & VM_MIXEDMAP) {
641 if (!pfn_valid(pfn))
642 return NULL;
643 goto out;
644 } else {
645 unsigned long off;
646 off = (addr - vma->vm_start) >> PAGE_SHIFT;
647 if (pfn == vma->vm_pgoff + off)
648 return NULL;
649 if (!is_cow_mapping(vma->vm_flags))
650 return NULL;
651 }
652 }
653
654 if (pmd_devmap(pmd))
655 return NULL;
656 if (is_huge_zero_pmd(pmd))
657 return NULL;
658 if (unlikely(pfn > highest_memmap_pfn))
659 return NULL;
660
661 /*
662 * NOTE! We still have PageReserved() pages in the page tables.
663 * eg. VDSO mappings can cause them to exist.
664 */
665out:
666 return pfn_to_page(pfn);
667}
668#endif
669
670static void restore_exclusive_pte(struct vm_area_struct *vma,
671 struct page *page, unsigned long address,
672 pte_t *ptep)
673{
674 pte_t pte;
675 swp_entry_t entry;
676
677 pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
678 if (pte_swp_soft_dirty(*ptep))
679 pte = pte_mksoft_dirty(pte);
680
681 entry = pte_to_swp_entry(*ptep);
682 if (pte_swp_uffd_wp(*ptep))
683 pte = pte_mkuffd_wp(pte);
684 else if (is_writable_device_exclusive_entry(entry))
685 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
686
687 VM_BUG_ON(pte_write(pte) && !(PageAnon(page) && PageAnonExclusive(page)));
688
689 /*
690 * No need to take a page reference as one was already
691 * created when the swap entry was made.
692 */
693 if (PageAnon(page))
694 page_add_anon_rmap(page, vma, address, RMAP_NONE);
695 else
696 /*
697 * Currently device exclusive access only supports anonymous
698 * memory so the entry shouldn't point to a filebacked page.
699 */
700 WARN_ON_ONCE(1);
701
702 set_pte_at(vma->vm_mm, address, ptep, pte);
703
704 /*
705 * No need to invalidate - it was non-present before. However
706 * secondary CPUs may have mappings that need invalidating.
707 */
708 update_mmu_cache(vma, address, ptep);
709}
710
711/*
712 * Tries to restore an exclusive pte if the page lock can be acquired without
713 * sleeping.
714 */
715static int
716try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
717 unsigned long addr)
718{
719 swp_entry_t entry = pte_to_swp_entry(*src_pte);
720 struct page *page = pfn_swap_entry_to_page(entry);
721
722 if (trylock_page(page)) {
723 restore_exclusive_pte(vma, page, addr, src_pte);
724 unlock_page(page);
725 return 0;
726 }
727
728 return -EBUSY;
729}
730
731/*
732 * copy one vm_area from one task to the other. Assumes the page tables
733 * already present in the new task to be cleared in the whole range
734 * covered by this vma.
735 */
736
737static unsigned long
738copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
739 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
740 struct vm_area_struct *src_vma, unsigned long addr, int *rss)
741{
742 unsigned long vm_flags = dst_vma->vm_flags;
743 pte_t pte = *src_pte;
744 struct page *page;
745 swp_entry_t entry = pte_to_swp_entry(pte);
746
747 if (likely(!non_swap_entry(entry))) {
748 if (swap_duplicate(entry) < 0)
749 return -EIO;
750
751 /* make sure dst_mm is on swapoff's mmlist. */
752 if (unlikely(list_empty(&dst_mm->mmlist))) {
753 spin_lock(&mmlist_lock);
754 if (list_empty(&dst_mm->mmlist))
755 list_add(&dst_mm->mmlist,
756 &src_mm->mmlist);
757 spin_unlock(&mmlist_lock);
758 }
759 /* Mark the swap entry as shared. */
760 if (pte_swp_exclusive(*src_pte)) {
761 pte = pte_swp_clear_exclusive(*src_pte);
762 set_pte_at(src_mm, addr, src_pte, pte);
763 }
764 rss[MM_SWAPENTS]++;
765 } else if (is_migration_entry(entry)) {
766 page = pfn_swap_entry_to_page(entry);
767
768 rss[mm_counter(page)]++;
769
770 if (!is_readable_migration_entry(entry) &&
771 is_cow_mapping(vm_flags)) {
772 /*
773 * COW mappings require pages in both parent and child
774 * to be set to read. A previously exclusive entry is
775 * now shared.
776 */
777 entry = make_readable_migration_entry(
778 swp_offset(entry));
779 pte = swp_entry_to_pte(entry);
780 if (pte_swp_soft_dirty(*src_pte))
781 pte = pte_swp_mksoft_dirty(pte);
782 if (pte_swp_uffd_wp(*src_pte))
783 pte = pte_swp_mkuffd_wp(pte);
784 set_pte_at(src_mm, addr, src_pte, pte);
785 }
786 } else if (is_device_private_entry(entry)) {
787 page = pfn_swap_entry_to_page(entry);
788
789 /*
790 * Update rss count even for unaddressable pages, as
791 * they should treated just like normal pages in this
792 * respect.
793 *
794 * We will likely want to have some new rss counters
795 * for unaddressable pages, at some point. But for now
796 * keep things as they are.
797 */
798 get_page(page);
799 rss[mm_counter(page)]++;
800 /* Cannot fail as these pages cannot get pinned. */
801 BUG_ON(page_try_dup_anon_rmap(page, false, src_vma));
802
803 /*
804 * We do not preserve soft-dirty information, because so
805 * far, checkpoint/restore is the only feature that
806 * requires that. And checkpoint/restore does not work
807 * when a device driver is involved (you cannot easily
808 * save and restore device driver state).
809 */
810 if (is_writable_device_private_entry(entry) &&
811 is_cow_mapping(vm_flags)) {
812 entry = make_readable_device_private_entry(
813 swp_offset(entry));
814 pte = swp_entry_to_pte(entry);
815 if (pte_swp_uffd_wp(*src_pte))
816 pte = pte_swp_mkuffd_wp(pte);
817 set_pte_at(src_mm, addr, src_pte, pte);
818 }
819 } else if (is_device_exclusive_entry(entry)) {
820 /*
821 * Make device exclusive entries present by restoring the
822 * original entry then copying as for a present pte. Device
823 * exclusive entries currently only support private writable
824 * (ie. COW) mappings.
825 */
826 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
827 if (try_restore_exclusive_pte(src_pte, src_vma, addr))
828 return -EBUSY;
829 return -ENOENT;
830 } else if (is_pte_marker_entry(entry)) {
831 if (is_swapin_error_entry(entry) || userfaultfd_wp(dst_vma))
832 set_pte_at(dst_mm, addr, dst_pte, pte);
833 return 0;
834 }
835 if (!userfaultfd_wp(dst_vma))
836 pte = pte_swp_clear_uffd_wp(pte);
837 set_pte_at(dst_mm, addr, dst_pte, pte);
838 return 0;
839}
840
841/*
842 * Copy a present and normal page.
843 *
844 * NOTE! The usual case is that this isn't required;
845 * instead, the caller can just increase the page refcount
846 * and re-use the pte the traditional way.
847 *
848 * And if we need a pre-allocated page but don't yet have
849 * one, return a negative error to let the preallocation
850 * code know so that it can do so outside the page table
851 * lock.
852 */
853static inline int
854copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
855 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
856 struct page **prealloc, struct page *page)
857{
858 struct page *new_page;
859 pte_t pte;
860
861 new_page = *prealloc;
862 if (!new_page)
863 return -EAGAIN;
864
865 /*
866 * We have a prealloc page, all good! Take it
867 * over and copy the page & arm it.
868 */
869 *prealloc = NULL;
870 copy_user_highpage(new_page, page, addr, src_vma);
871 __SetPageUptodate(new_page);
872 page_add_new_anon_rmap(new_page, dst_vma, addr);
873 lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
874 rss[mm_counter(new_page)]++;
875
876 /* All done, just insert the new page copy in the child */
877 pte = mk_pte(new_page, dst_vma->vm_page_prot);
878 pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
879 if (userfaultfd_pte_wp(dst_vma, *src_pte))
880 /* Uffd-wp needs to be delivered to dest pte as well */
881 pte = pte_wrprotect(pte_mkuffd_wp(pte));
882 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
883 return 0;
884}
885
886/*
887 * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
888 * is required to copy this pte.
889 */
890static inline int
891copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
892 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
893 struct page **prealloc)
894{
895 struct mm_struct *src_mm = src_vma->vm_mm;
896 unsigned long vm_flags = src_vma->vm_flags;
897 pte_t pte = *src_pte;
898 struct page *page;
899
900 page = vm_normal_page(src_vma, addr, pte);
901 if (page && PageAnon(page)) {
902 /*
903 * If this page may have been pinned by the parent process,
904 * copy the page immediately for the child so that we'll always
905 * guarantee the pinned page won't be randomly replaced in the
906 * future.
907 */
908 get_page(page);
909 if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) {
910 /* Page maybe pinned, we have to copy. */
911 put_page(page);
912 return copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
913 addr, rss, prealloc, page);
914 }
915 rss[mm_counter(page)]++;
916 } else if (page) {
917 get_page(page);
918 page_dup_file_rmap(page, false);
919 rss[mm_counter(page)]++;
920 }
921
922 /*
923 * If it's a COW mapping, write protect it both
924 * in the parent and the child
925 */
926 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
927 ptep_set_wrprotect(src_mm, addr, src_pte);
928 pte = pte_wrprotect(pte);
929 }
930 VM_BUG_ON(page && PageAnon(page) && PageAnonExclusive(page));
931
932 /*
933 * If it's a shared mapping, mark it clean in
934 * the child
935 */
936 if (vm_flags & VM_SHARED)
937 pte = pte_mkclean(pte);
938 pte = pte_mkold(pte);
939
940 if (!userfaultfd_wp(dst_vma))
941 pte = pte_clear_uffd_wp(pte);
942
943 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
944 return 0;
945}
946
947static inline struct page *
948page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
949 unsigned long addr)
950{
951 struct page *new_page;
952
953 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr);
954 if (!new_page)
955 return NULL;
956
957 if (mem_cgroup_charge(page_folio(new_page), src_mm, GFP_KERNEL)) {
958 put_page(new_page);
959 return NULL;
960 }
961 cgroup_throttle_swaprate(new_page, GFP_KERNEL);
962
963 return new_page;
964}
965
966static int
967copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
968 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
969 unsigned long end)
970{
971 struct mm_struct *dst_mm = dst_vma->vm_mm;
972 struct mm_struct *src_mm = src_vma->vm_mm;
973 pte_t *orig_src_pte, *orig_dst_pte;
974 pte_t *src_pte, *dst_pte;
975 spinlock_t *src_ptl, *dst_ptl;
976 int progress, ret = 0;
977 int rss[NR_MM_COUNTERS];
978 swp_entry_t entry = (swp_entry_t){0};
979 struct page *prealloc = NULL;
980
981again:
982 progress = 0;
983 init_rss_vec(rss);
984
985 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
986 if (!dst_pte) {
987 ret = -ENOMEM;
988 goto out;
989 }
990 src_pte = pte_offset_map(src_pmd, addr);
991 src_ptl = pte_lockptr(src_mm, src_pmd);
992 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
993 orig_src_pte = src_pte;
994 orig_dst_pte = dst_pte;
995 arch_enter_lazy_mmu_mode();
996
997 do {
998 /*
999 * We are holding two locks at this point - either of them
1000 * could generate latencies in another task on another CPU.
1001 */
1002 if (progress >= 32) {
1003 progress = 0;
1004 if (need_resched() ||
1005 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1006 break;
1007 }
1008 if (pte_none(*src_pte)) {
1009 progress++;
1010 continue;
1011 }
1012 if (unlikely(!pte_present(*src_pte))) {
1013 ret = copy_nonpresent_pte(dst_mm, src_mm,
1014 dst_pte, src_pte,
1015 dst_vma, src_vma,
1016 addr, rss);
1017 if (ret == -EIO) {
1018 entry = pte_to_swp_entry(*src_pte);
1019 break;
1020 } else if (ret == -EBUSY) {
1021 break;
1022 } else if (!ret) {
1023 progress += 8;
1024 continue;
1025 }
1026
1027 /*
1028 * Device exclusive entry restored, continue by copying
1029 * the now present pte.
1030 */
1031 WARN_ON_ONCE(ret != -ENOENT);
1032 }
1033 /* copy_present_pte() will clear `*prealloc' if consumed */
1034 ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
1035 addr, rss, &prealloc);
1036 /*
1037 * If we need a pre-allocated page for this pte, drop the
1038 * locks, allocate, and try again.
1039 */
1040 if (unlikely(ret == -EAGAIN))
1041 break;
1042 if (unlikely(prealloc)) {
1043 /*
1044 * pre-alloc page cannot be reused by next time so as
1045 * to strictly follow mempolicy (e.g., alloc_page_vma()
1046 * will allocate page according to address). This
1047 * could only happen if one pinned pte changed.
1048 */
1049 put_page(prealloc);
1050 prealloc = NULL;
1051 }
1052 progress += 8;
1053 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1054
1055 arch_leave_lazy_mmu_mode();
1056 spin_unlock(src_ptl);
1057 pte_unmap(orig_src_pte);
1058 add_mm_rss_vec(dst_mm, rss);
1059 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1060 cond_resched();
1061
1062 if (ret == -EIO) {
1063 VM_WARN_ON_ONCE(!entry.val);
1064 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1065 ret = -ENOMEM;
1066 goto out;
1067 }
1068 entry.val = 0;
1069 } else if (ret == -EBUSY) {
1070 goto out;
1071 } else if (ret == -EAGAIN) {
1072 prealloc = page_copy_prealloc(src_mm, src_vma, addr);
1073 if (!prealloc)
1074 return -ENOMEM;
1075 } else if (ret) {
1076 VM_WARN_ON_ONCE(1);
1077 }
1078
1079 /* We've captured and resolved the error. Reset, try again. */
1080 ret = 0;
1081
1082 if (addr != end)
1083 goto again;
1084out:
1085 if (unlikely(prealloc))
1086 put_page(prealloc);
1087 return ret;
1088}
1089
1090static inline int
1091copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1092 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1093 unsigned long end)
1094{
1095 struct mm_struct *dst_mm = dst_vma->vm_mm;
1096 struct mm_struct *src_mm = src_vma->vm_mm;
1097 pmd_t *src_pmd, *dst_pmd;
1098 unsigned long next;
1099
1100 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1101 if (!dst_pmd)
1102 return -ENOMEM;
1103 src_pmd = pmd_offset(src_pud, addr);
1104 do {
1105 next = pmd_addr_end(addr, end);
1106 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1107 || pmd_devmap(*src_pmd)) {
1108 int err;
1109 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1110 err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1111 addr, dst_vma, src_vma);
1112 if (err == -ENOMEM)
1113 return -ENOMEM;
1114 if (!err)
1115 continue;
1116 /* fall through */
1117 }
1118 if (pmd_none_or_clear_bad(src_pmd))
1119 continue;
1120 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1121 addr, next))
1122 return -ENOMEM;
1123 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1124 return 0;
1125}
1126
1127static inline int
1128copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1129 p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1130 unsigned long end)
1131{
1132 struct mm_struct *dst_mm = dst_vma->vm_mm;
1133 struct mm_struct *src_mm = src_vma->vm_mm;
1134 pud_t *src_pud, *dst_pud;
1135 unsigned long next;
1136
1137 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1138 if (!dst_pud)
1139 return -ENOMEM;
1140 src_pud = pud_offset(src_p4d, addr);
1141 do {
1142 next = pud_addr_end(addr, end);
1143 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1144 int err;
1145
1146 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1147 err = copy_huge_pud(dst_mm, src_mm,
1148 dst_pud, src_pud, addr, src_vma);
1149 if (err == -ENOMEM)
1150 return -ENOMEM;
1151 if (!err)
1152 continue;
1153 /* fall through */
1154 }
1155 if (pud_none_or_clear_bad(src_pud))
1156 continue;
1157 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1158 addr, next))
1159 return -ENOMEM;
1160 } while (dst_pud++, src_pud++, addr = next, addr != end);
1161 return 0;
1162}
1163
1164static inline int
1165copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1166 pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1167 unsigned long end)
1168{
1169 struct mm_struct *dst_mm = dst_vma->vm_mm;
1170 p4d_t *src_p4d, *dst_p4d;
1171 unsigned long next;
1172
1173 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1174 if (!dst_p4d)
1175 return -ENOMEM;
1176 src_p4d = p4d_offset(src_pgd, addr);
1177 do {
1178 next = p4d_addr_end(addr, end);
1179 if (p4d_none_or_clear_bad(src_p4d))
1180 continue;
1181 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1182 addr, next))
1183 return -ENOMEM;
1184 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1185 return 0;
1186}
1187
1188/*
1189 * Return true if the vma needs to copy the pgtable during this fork(). Return
1190 * false when we can speed up fork() by allowing lazy page faults later until
1191 * when the child accesses the memory range.
1192 */
1193static bool
1194vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1195{
1196 /*
1197 * Always copy pgtables when dst_vma has uffd-wp enabled even if it's
1198 * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable
1199 * contains uffd-wp protection information, that's something we can't
1200 * retrieve from page cache, and skip copying will lose those info.
1201 */
1202 if (userfaultfd_wp(dst_vma))
1203 return true;
1204
1205 if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
1206 return true;
1207
1208 if (src_vma->anon_vma)
1209 return true;
1210
1211 /*
1212 * Don't copy ptes where a page fault will fill them correctly. Fork
1213 * becomes much lighter when there are big shared or private readonly
1214 * mappings. The tradeoff is that copy_page_range is more efficient
1215 * than faulting.
1216 */
1217 return false;
1218}
1219
1220int
1221copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1222{
1223 pgd_t *src_pgd, *dst_pgd;
1224 unsigned long next;
1225 unsigned long addr = src_vma->vm_start;
1226 unsigned long end = src_vma->vm_end;
1227 struct mm_struct *dst_mm = dst_vma->vm_mm;
1228 struct mm_struct *src_mm = src_vma->vm_mm;
1229 struct mmu_notifier_range range;
1230 bool is_cow;
1231 int ret;
1232
1233 if (!vma_needs_copy(dst_vma, src_vma))
1234 return 0;
1235
1236 if (is_vm_hugetlb_page(src_vma))
1237 return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma);
1238
1239 if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1240 /*
1241 * We do not free on error cases below as remove_vma
1242 * gets called on error from higher level routine
1243 */
1244 ret = track_pfn_copy(src_vma);
1245 if (ret)
1246 return ret;
1247 }
1248
1249 /*
1250 * We need to invalidate the secondary MMU mappings only when
1251 * there could be a permission downgrade on the ptes of the
1252 * parent mm. And a permission downgrade will only happen if
1253 * is_cow_mapping() returns true.
1254 */
1255 is_cow = is_cow_mapping(src_vma->vm_flags);
1256
1257 if (is_cow) {
1258 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1259 0, src_vma, src_mm, addr, end);
1260 mmu_notifier_invalidate_range_start(&range);
1261 /*
1262 * Disabling preemption is not needed for the write side, as
1263 * the read side doesn't spin, but goes to the mmap_lock.
1264 *
1265 * Use the raw variant of the seqcount_t write API to avoid
1266 * lockdep complaining about preemptibility.
1267 */
1268 mmap_assert_write_locked(src_mm);
1269 raw_write_seqcount_begin(&src_mm->write_protect_seq);
1270 }
1271
1272 ret = 0;
1273 dst_pgd = pgd_offset(dst_mm, addr);
1274 src_pgd = pgd_offset(src_mm, addr);
1275 do {
1276 next = pgd_addr_end(addr, end);
1277 if (pgd_none_or_clear_bad(src_pgd))
1278 continue;
1279 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1280 addr, next))) {
1281 ret = -ENOMEM;
1282 break;
1283 }
1284 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1285
1286 if (is_cow) {
1287 raw_write_seqcount_end(&src_mm->write_protect_seq);
1288 mmu_notifier_invalidate_range_end(&range);
1289 }
1290 return ret;
1291}
1292
1293/* Whether we should zap all COWed (private) pages too */
1294static inline bool should_zap_cows(struct zap_details *details)
1295{
1296 /* By default, zap all pages */
1297 if (!details)
1298 return true;
1299
1300 /* Or, we zap COWed pages only if the caller wants to */
1301 return details->even_cows;
1302}
1303
1304/* Decides whether we should zap this page with the page pointer specified */
1305static inline bool should_zap_page(struct zap_details *details, struct page *page)
1306{
1307 /* If we can make a decision without *page.. */
1308 if (should_zap_cows(details))
1309 return true;
1310
1311 /* E.g. the caller passes NULL for the case of a zero page */
1312 if (!page)
1313 return true;
1314
1315 /* Otherwise we should only zap non-anon pages */
1316 return !PageAnon(page);
1317}
1318
1319static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
1320{
1321 if (!details)
1322 return false;
1323
1324 return details->zap_flags & ZAP_FLAG_DROP_MARKER;
1325}
1326
1327/*
1328 * This function makes sure that we'll replace the none pte with an uffd-wp
1329 * swap special pte marker when necessary. Must be with the pgtable lock held.
1330 */
1331static inline void
1332zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
1333 unsigned long addr, pte_t *pte,
1334 struct zap_details *details, pte_t pteval)
1335{
1336 if (zap_drop_file_uffd_wp(details))
1337 return;
1338
1339 pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
1340}
1341
1342static unsigned long zap_pte_range(struct mmu_gather *tlb,
1343 struct vm_area_struct *vma, pmd_t *pmd,
1344 unsigned long addr, unsigned long end,
1345 struct zap_details *details)
1346{
1347 struct mm_struct *mm = tlb->mm;
1348 int force_flush = 0;
1349 int rss[NR_MM_COUNTERS];
1350 spinlock_t *ptl;
1351 pte_t *start_pte;
1352 pte_t *pte;
1353 swp_entry_t entry;
1354
1355 tlb_change_page_size(tlb, PAGE_SIZE);
1356again:
1357 init_rss_vec(rss);
1358 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1359 pte = start_pte;
1360 flush_tlb_batched_pending(mm);
1361 arch_enter_lazy_mmu_mode();
1362 do {
1363 pte_t ptent = *pte;
1364 struct page *page;
1365
1366 if (pte_none(ptent))
1367 continue;
1368
1369 if (need_resched())
1370 break;
1371
1372 if (pte_present(ptent)) {
1373 unsigned int delay_rmap;
1374
1375 page = vm_normal_page(vma, addr, ptent);
1376 if (unlikely(!should_zap_page(details, page)))
1377 continue;
1378 ptent = ptep_get_and_clear_full(mm, addr, pte,
1379 tlb->fullmm);
1380 tlb_remove_tlb_entry(tlb, pte, addr);
1381 zap_install_uffd_wp_if_needed(vma, addr, pte, details,
1382 ptent);
1383 if (unlikely(!page))
1384 continue;
1385
1386 delay_rmap = 0;
1387 if (!PageAnon(page)) {
1388 if (pte_dirty(ptent)) {
1389 set_page_dirty(page);
1390 if (tlb_delay_rmap(tlb)) {
1391 delay_rmap = 1;
1392 force_flush = 1;
1393 }
1394 }
1395 if (pte_young(ptent) &&
1396 likely(!(vma->vm_flags & VM_SEQ_READ)))
1397 mark_page_accessed(page);
1398 }
1399 rss[mm_counter(page)]--;
1400 if (!delay_rmap) {
1401 page_remove_rmap(page, vma, false);
1402 if (unlikely(page_mapcount(page) < 0))
1403 print_bad_pte(vma, addr, ptent, page);
1404 }
1405 if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) {
1406 force_flush = 1;
1407 addr += PAGE_SIZE;
1408 break;
1409 }
1410 continue;
1411 }
1412
1413 entry = pte_to_swp_entry(ptent);
1414 if (is_device_private_entry(entry) ||
1415 is_device_exclusive_entry(entry)) {
1416 page = pfn_swap_entry_to_page(entry);
1417 if (unlikely(!should_zap_page(details, page)))
1418 continue;
1419 /*
1420 * Both device private/exclusive mappings should only
1421 * work with anonymous page so far, so we don't need to
1422 * consider uffd-wp bit when zap. For more information,
1423 * see zap_install_uffd_wp_if_needed().
1424 */
1425 WARN_ON_ONCE(!vma_is_anonymous(vma));
1426 rss[mm_counter(page)]--;
1427 if (is_device_private_entry(entry))
1428 page_remove_rmap(page, vma, false);
1429 put_page(page);
1430 } else if (!non_swap_entry(entry)) {
1431 /* Genuine swap entry, hence a private anon page */
1432 if (!should_zap_cows(details))
1433 continue;
1434 rss[MM_SWAPENTS]--;
1435 if (unlikely(!free_swap_and_cache(entry)))
1436 print_bad_pte(vma, addr, ptent, NULL);
1437 } else if (is_migration_entry(entry)) {
1438 page = pfn_swap_entry_to_page(entry);
1439 if (!should_zap_page(details, page))
1440 continue;
1441 rss[mm_counter(page)]--;
1442 } else if (pte_marker_entry_uffd_wp(entry)) {
1443 /* Only drop the uffd-wp marker if explicitly requested */
1444 if (!zap_drop_file_uffd_wp(details))
1445 continue;
1446 } else if (is_hwpoison_entry(entry) ||
1447 is_swapin_error_entry(entry)) {
1448 if (!should_zap_cows(details))
1449 continue;
1450 } else {
1451 /* We should have covered all the swap entry types */
1452 WARN_ON_ONCE(1);
1453 }
1454 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1455 zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent);
1456 } while (pte++, addr += PAGE_SIZE, addr != end);
1457
1458 add_mm_rss_vec(mm, rss);
1459 arch_leave_lazy_mmu_mode();
1460
1461 /* Do the actual TLB flush before dropping ptl */
1462 if (force_flush) {
1463 tlb_flush_mmu_tlbonly(tlb);
1464 tlb_flush_rmaps(tlb, vma);
1465 }
1466 pte_unmap_unlock(start_pte, ptl);
1467
1468 /*
1469 * If we forced a TLB flush (either due to running out of
1470 * batch buffers or because we needed to flush dirty TLB
1471 * entries before releasing the ptl), free the batched
1472 * memory too. Restart if we didn't do everything.
1473 */
1474 if (force_flush) {
1475 force_flush = 0;
1476 tlb_flush_mmu(tlb);
1477 }
1478
1479 if (addr != end) {
1480 cond_resched();
1481 goto again;
1482 }
1483
1484 return addr;
1485}
1486
1487static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1488 struct vm_area_struct *vma, pud_t *pud,
1489 unsigned long addr, unsigned long end,
1490 struct zap_details *details)
1491{
1492 pmd_t *pmd;
1493 unsigned long next;
1494
1495 pmd = pmd_offset(pud, addr);
1496 do {
1497 next = pmd_addr_end(addr, end);
1498 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1499 if (next - addr != HPAGE_PMD_SIZE)
1500 __split_huge_pmd(vma, pmd, addr, false, NULL);
1501 else if (zap_huge_pmd(tlb, vma, pmd, addr))
1502 goto next;
1503 /* fall through */
1504 } else if (details && details->single_folio &&
1505 folio_test_pmd_mappable(details->single_folio) &&
1506 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1507 spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1508 /*
1509 * Take and drop THP pmd lock so that we cannot return
1510 * prematurely, while zap_huge_pmd() has cleared *pmd,
1511 * but not yet decremented compound_mapcount().
1512 */
1513 spin_unlock(ptl);
1514 }
1515
1516 /*
1517 * Here there can be other concurrent MADV_DONTNEED or
1518 * trans huge page faults running, and if the pmd is
1519 * none or trans huge it can change under us. This is
1520 * because MADV_DONTNEED holds the mmap_lock in read
1521 * mode.
1522 */
1523 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1524 goto next;
1525 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1526next:
1527 cond_resched();
1528 } while (pmd++, addr = next, addr != end);
1529
1530 return addr;
1531}
1532
1533static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1534 struct vm_area_struct *vma, p4d_t *p4d,
1535 unsigned long addr, unsigned long end,
1536 struct zap_details *details)
1537{
1538 pud_t *pud;
1539 unsigned long next;
1540
1541 pud = pud_offset(p4d, addr);
1542 do {
1543 next = pud_addr_end(addr, end);
1544 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1545 if (next - addr != HPAGE_PUD_SIZE) {
1546 mmap_assert_locked(tlb->mm);
1547 split_huge_pud(vma, pud, addr);
1548 } else if (zap_huge_pud(tlb, vma, pud, addr))
1549 goto next;
1550 /* fall through */
1551 }
1552 if (pud_none_or_clear_bad(pud))
1553 continue;
1554 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1555next:
1556 cond_resched();
1557 } while (pud++, addr = next, addr != end);
1558
1559 return addr;
1560}
1561
1562static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1563 struct vm_area_struct *vma, pgd_t *pgd,
1564 unsigned long addr, unsigned long end,
1565 struct zap_details *details)
1566{
1567 p4d_t *p4d;
1568 unsigned long next;
1569
1570 p4d = p4d_offset(pgd, addr);
1571 do {
1572 next = p4d_addr_end(addr, end);
1573 if (p4d_none_or_clear_bad(p4d))
1574 continue;
1575 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1576 } while (p4d++, addr = next, addr != end);
1577
1578 return addr;
1579}
1580
1581void unmap_page_range(struct mmu_gather *tlb,
1582 struct vm_area_struct *vma,
1583 unsigned long addr, unsigned long end,
1584 struct zap_details *details)
1585{
1586 pgd_t *pgd;
1587 unsigned long next;
1588
1589 BUG_ON(addr >= end);
1590 tlb_start_vma(tlb, vma);
1591 pgd = pgd_offset(vma->vm_mm, addr);
1592 do {
1593 next = pgd_addr_end(addr, end);
1594 if (pgd_none_or_clear_bad(pgd))
1595 continue;
1596 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1597 } while (pgd++, addr = next, addr != end);
1598 tlb_end_vma(tlb, vma);
1599}
1600
1601
1602static void unmap_single_vma(struct mmu_gather *tlb,
1603 struct vm_area_struct *vma, unsigned long start_addr,
1604 unsigned long end_addr,
1605 struct zap_details *details)
1606{
1607 unsigned long start = max(vma->vm_start, start_addr);
1608 unsigned long end;
1609
1610 if (start >= vma->vm_end)
1611 return;
1612 end = min(vma->vm_end, end_addr);
1613 if (end <= vma->vm_start)
1614 return;
1615
1616 if (vma->vm_file)
1617 uprobe_munmap(vma, start, end);
1618
1619 if (unlikely(vma->vm_flags & VM_PFNMAP))
1620 untrack_pfn(vma, 0, 0);
1621
1622 if (start != end) {
1623 if (unlikely(is_vm_hugetlb_page(vma))) {
1624 /*
1625 * It is undesirable to test vma->vm_file as it
1626 * should be non-null for valid hugetlb area.
1627 * However, vm_file will be NULL in the error
1628 * cleanup path of mmap_region. When
1629 * hugetlbfs ->mmap method fails,
1630 * mmap_region() nullifies vma->vm_file
1631 * before calling this function to clean up.
1632 * Since no pte has actually been setup, it is
1633 * safe to do nothing in this case.
1634 */
1635 if (vma->vm_file) {
1636 zap_flags_t zap_flags = details ?
1637 details->zap_flags : 0;
1638 __unmap_hugepage_range_final(tlb, vma, start, end,
1639 NULL, zap_flags);
1640 }
1641 } else
1642 unmap_page_range(tlb, vma, start, end, details);
1643 }
1644}
1645
1646/**
1647 * unmap_vmas - unmap a range of memory covered by a list of vma's
1648 * @tlb: address of the caller's struct mmu_gather
1649 * @mt: the maple tree
1650 * @vma: the starting vma
1651 * @start_addr: virtual address at which to start unmapping
1652 * @end_addr: virtual address at which to end unmapping
1653 *
1654 * Unmap all pages in the vma list.
1655 *
1656 * Only addresses between `start' and `end' will be unmapped.
1657 *
1658 * The VMA list must be sorted in ascending virtual address order.
1659 *
1660 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1661 * range after unmap_vmas() returns. So the only responsibility here is to
1662 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1663 * drops the lock and schedules.
1664 */
1665void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
1666 struct vm_area_struct *vma, unsigned long start_addr,
1667 unsigned long end_addr)
1668{
1669 struct mmu_notifier_range range;
1670 struct zap_details details = {
1671 .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP,
1672 /* Careful - we need to zap private pages too! */
1673 .even_cows = true,
1674 };
1675 MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
1676
1677 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1678 start_addr, end_addr);
1679 mmu_notifier_invalidate_range_start(&range);
1680 do {
1681 unmap_single_vma(tlb, vma, start_addr, end_addr, &details);
1682 } while ((vma = mas_find(&mas, end_addr - 1)) != NULL);
1683 mmu_notifier_invalidate_range_end(&range);
1684}
1685
1686/**
1687 * zap_page_range - remove user pages in a given range
1688 * @vma: vm_area_struct holding the applicable pages
1689 * @start: starting address of pages to zap
1690 * @size: number of bytes to zap
1691 *
1692 * Caller must protect the VMA list
1693 */
1694void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1695 unsigned long size)
1696{
1697 struct maple_tree *mt = &vma->vm_mm->mm_mt;
1698 unsigned long end = start + size;
1699 struct mmu_notifier_range range;
1700 struct mmu_gather tlb;
1701 MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
1702
1703 lru_add_drain();
1704 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1705 start, start + size);
1706 tlb_gather_mmu(&tlb, vma->vm_mm);
1707 update_hiwater_rss(vma->vm_mm);
1708 mmu_notifier_invalidate_range_start(&range);
1709 do {
1710 unmap_single_vma(&tlb, vma, start, range.end, NULL);
1711 } while ((vma = mas_find(&mas, end - 1)) != NULL);
1712 mmu_notifier_invalidate_range_end(&range);
1713 tlb_finish_mmu(&tlb);
1714}
1715
1716/**
1717 * zap_page_range_single - remove user pages in a given range
1718 * @vma: vm_area_struct holding the applicable pages
1719 * @address: starting address of pages to zap
1720 * @size: number of bytes to zap
1721 * @details: details of shared cache invalidation
1722 *
1723 * The range must fit into one VMA.
1724 */
1725void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1726 unsigned long size, struct zap_details *details)
1727{
1728 const unsigned long end = address + size;
1729 struct mmu_notifier_range range;
1730 struct mmu_gather tlb;
1731
1732 lru_add_drain();
1733 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1734 address, end);
1735 if (is_vm_hugetlb_page(vma))
1736 adjust_range_if_pmd_sharing_possible(vma, &range.start,
1737 &range.end);
1738 tlb_gather_mmu(&tlb, vma->vm_mm);
1739 update_hiwater_rss(vma->vm_mm);
1740 mmu_notifier_invalidate_range_start(&range);
1741 /*
1742 * unmap 'address-end' not 'range.start-range.end' as range
1743 * could have been expanded for hugetlb pmd sharing.
1744 */
1745 unmap_single_vma(&tlb, vma, address, end, details);
1746 mmu_notifier_invalidate_range_end(&range);
1747 tlb_finish_mmu(&tlb);
1748}
1749
1750/**
1751 * zap_vma_ptes - remove ptes mapping the vma
1752 * @vma: vm_area_struct holding ptes to be zapped
1753 * @address: starting address of pages to zap
1754 * @size: number of bytes to zap
1755 *
1756 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1757 *
1758 * The entire address range must be fully contained within the vma.
1759 *
1760 */
1761void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1762 unsigned long size)
1763{
1764 if (!range_in_vma(vma, address, address + size) ||
1765 !(vma->vm_flags & VM_PFNMAP))
1766 return;
1767
1768 zap_page_range_single(vma, address, size, NULL);
1769}
1770EXPORT_SYMBOL_GPL(zap_vma_ptes);
1771
1772static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1773{
1774 pgd_t *pgd;
1775 p4d_t *p4d;
1776 pud_t *pud;
1777 pmd_t *pmd;
1778
1779 pgd = pgd_offset(mm, addr);
1780 p4d = p4d_alloc(mm, pgd, addr);
1781 if (!p4d)
1782 return NULL;
1783 pud = pud_alloc(mm, p4d, addr);
1784 if (!pud)
1785 return NULL;
1786 pmd = pmd_alloc(mm, pud, addr);
1787 if (!pmd)
1788 return NULL;
1789
1790 VM_BUG_ON(pmd_trans_huge(*pmd));
1791 return pmd;
1792}
1793
1794pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1795 spinlock_t **ptl)
1796{
1797 pmd_t *pmd = walk_to_pmd(mm, addr);
1798
1799 if (!pmd)
1800 return NULL;
1801 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1802}
1803
1804static int validate_page_before_insert(struct page *page)
1805{
1806 if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1807 return -EINVAL;
1808 flush_dcache_page(page);
1809 return 0;
1810}
1811
1812static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
1813 unsigned long addr, struct page *page, pgprot_t prot)
1814{
1815 if (!pte_none(*pte))
1816 return -EBUSY;
1817 /* Ok, finally just insert the thing.. */
1818 get_page(page);
1819 inc_mm_counter(vma->vm_mm, mm_counter_file(page));
1820 page_add_file_rmap(page, vma, false);
1821 set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
1822 return 0;
1823}
1824
1825/*
1826 * This is the old fallback for page remapping.
1827 *
1828 * For historical reasons, it only allows reserved pages. Only
1829 * old drivers should use this, and they needed to mark their
1830 * pages reserved for the old functions anyway.
1831 */
1832static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1833 struct page *page, pgprot_t prot)
1834{
1835 int retval;
1836 pte_t *pte;
1837 spinlock_t *ptl;
1838
1839 retval = validate_page_before_insert(page);
1840 if (retval)
1841 goto out;
1842 retval = -ENOMEM;
1843 pte = get_locked_pte(vma->vm_mm, addr, &ptl);
1844 if (!pte)
1845 goto out;
1846 retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
1847 pte_unmap_unlock(pte, ptl);
1848out:
1849 return retval;
1850}
1851
1852#ifdef pte_index
1853static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
1854 unsigned long addr, struct page *page, pgprot_t prot)
1855{
1856 int err;
1857
1858 if (!page_count(page))
1859 return -EINVAL;
1860 err = validate_page_before_insert(page);
1861 if (err)
1862 return err;
1863 return insert_page_into_pte_locked(vma, pte, addr, page, prot);
1864}
1865
1866/* insert_pages() amortizes the cost of spinlock operations
1867 * when inserting pages in a loop. Arch *must* define pte_index.
1868 */
1869static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
1870 struct page **pages, unsigned long *num, pgprot_t prot)
1871{
1872 pmd_t *pmd = NULL;
1873 pte_t *start_pte, *pte;
1874 spinlock_t *pte_lock;
1875 struct mm_struct *const mm = vma->vm_mm;
1876 unsigned long curr_page_idx = 0;
1877 unsigned long remaining_pages_total = *num;
1878 unsigned long pages_to_write_in_pmd;
1879 int ret;
1880more:
1881 ret = -EFAULT;
1882 pmd = walk_to_pmd(mm, addr);
1883 if (!pmd)
1884 goto out;
1885
1886 pages_to_write_in_pmd = min_t(unsigned long,
1887 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
1888
1889 /* Allocate the PTE if necessary; takes PMD lock once only. */
1890 ret = -ENOMEM;
1891 if (pte_alloc(mm, pmd))
1892 goto out;
1893
1894 while (pages_to_write_in_pmd) {
1895 int pte_idx = 0;
1896 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
1897
1898 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
1899 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
1900 int err = insert_page_in_batch_locked(vma, pte,
1901 addr, pages[curr_page_idx], prot);
1902 if (unlikely(err)) {
1903 pte_unmap_unlock(start_pte, pte_lock);
1904 ret = err;
1905 remaining_pages_total -= pte_idx;
1906 goto out;
1907 }
1908 addr += PAGE_SIZE;
1909 ++curr_page_idx;
1910 }
1911 pte_unmap_unlock(start_pte, pte_lock);
1912 pages_to_write_in_pmd -= batch_size;
1913 remaining_pages_total -= batch_size;
1914 }
1915 if (remaining_pages_total)
1916 goto more;
1917 ret = 0;
1918out:
1919 *num = remaining_pages_total;
1920 return ret;
1921}
1922#endif /* ifdef pte_index */
1923
1924/**
1925 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1926 * @vma: user vma to map to
1927 * @addr: target start user address of these pages
1928 * @pages: source kernel pages
1929 * @num: in: number of pages to map. out: number of pages that were *not*
1930 * mapped. (0 means all pages were successfully mapped).
1931 *
1932 * Preferred over vm_insert_page() when inserting multiple pages.
1933 *
1934 * In case of error, we may have mapped a subset of the provided
1935 * pages. It is the caller's responsibility to account for this case.
1936 *
1937 * The same restrictions apply as in vm_insert_page().
1938 */
1939int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
1940 struct page **pages, unsigned long *num)
1941{
1942#ifdef pte_index
1943 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
1944
1945 if (addr < vma->vm_start || end_addr >= vma->vm_end)
1946 return -EFAULT;
1947 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1948 BUG_ON(mmap_read_trylock(vma->vm_mm));
1949 BUG_ON(vma->vm_flags & VM_PFNMAP);
1950 vma->vm_flags |= VM_MIXEDMAP;
1951 }
1952 /* Defer page refcount checking till we're about to map that page. */
1953 return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
1954#else
1955 unsigned long idx = 0, pgcount = *num;
1956 int err = -EINVAL;
1957
1958 for (; idx < pgcount; ++idx) {
1959 err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
1960 if (err)
1961 break;
1962 }
1963 *num = pgcount - idx;
1964 return err;
1965#endif /* ifdef pte_index */
1966}
1967EXPORT_SYMBOL(vm_insert_pages);
1968
1969/**
1970 * vm_insert_page - insert single page into user vma
1971 * @vma: user vma to map to
1972 * @addr: target user address of this page
1973 * @page: source kernel page
1974 *
1975 * This allows drivers to insert individual pages they've allocated
1976 * into a user vma.
1977 *
1978 * The page has to be a nice clean _individual_ kernel allocation.
1979 * If you allocate a compound page, you need to have marked it as
1980 * such (__GFP_COMP), or manually just split the page up yourself
1981 * (see split_page()).
1982 *
1983 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1984 * took an arbitrary page protection parameter. This doesn't allow
1985 * that. Your vma protection will have to be set up correctly, which
1986 * means that if you want a shared writable mapping, you'd better
1987 * ask for a shared writable mapping!
1988 *
1989 * The page does not need to be reserved.
1990 *
1991 * Usually this function is called from f_op->mmap() handler
1992 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
1993 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1994 * function from other places, for example from page-fault handler.
1995 *
1996 * Return: %0 on success, negative error code otherwise.
1997 */
1998int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1999 struct page *page)
2000{
2001 if (addr < vma->vm_start || addr >= vma->vm_end)
2002 return -EFAULT;
2003 if (!page_count(page))
2004 return -EINVAL;
2005 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2006 BUG_ON(mmap_read_trylock(vma->vm_mm));
2007 BUG_ON(vma->vm_flags & VM_PFNMAP);
2008 vma->vm_flags |= VM_MIXEDMAP;
2009 }
2010 return insert_page(vma, addr, page, vma->vm_page_prot);
2011}
2012EXPORT_SYMBOL(vm_insert_page);
2013
2014/*
2015 * __vm_map_pages - maps range of kernel pages into user vma
2016 * @vma: user vma to map to
2017 * @pages: pointer to array of source kernel pages
2018 * @num: number of pages in page array
2019 * @offset: user's requested vm_pgoff
2020 *
2021 * This allows drivers to map range of kernel pages into a user vma.
2022 *
2023 * Return: 0 on success and error code otherwise.
2024 */
2025static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2026 unsigned long num, unsigned long offset)
2027{
2028 unsigned long count = vma_pages(vma);
2029 unsigned long uaddr = vma->vm_start;
2030 int ret, i;
2031
2032 /* Fail if the user requested offset is beyond the end of the object */
2033 if (offset >= num)
2034 return -ENXIO;
2035
2036 /* Fail if the user requested size exceeds available object size */
2037 if (count > num - offset)
2038 return -ENXIO;
2039
2040 for (i = 0; i < count; i++) {
2041 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
2042 if (ret < 0)
2043 return ret;
2044 uaddr += PAGE_SIZE;
2045 }
2046
2047 return 0;
2048}
2049
2050/**
2051 * vm_map_pages - maps range of kernel pages starts with non zero offset
2052 * @vma: user vma to map to
2053 * @pages: pointer to array of source kernel pages
2054 * @num: number of pages in page array
2055 *
2056 * Maps an object consisting of @num pages, catering for the user's
2057 * requested vm_pgoff
2058 *
2059 * If we fail to insert any page into the vma, the function will return
2060 * immediately leaving any previously inserted pages present. Callers
2061 * from the mmap handler may immediately return the error as their caller
2062 * will destroy the vma, removing any successfully inserted pages. Other
2063 * callers should make their own arrangements for calling unmap_region().
2064 *
2065 * Context: Process context. Called by mmap handlers.
2066 * Return: 0 on success and error code otherwise.
2067 */
2068int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2069 unsigned long num)
2070{
2071 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2072}
2073EXPORT_SYMBOL(vm_map_pages);
2074
2075/**
2076 * vm_map_pages_zero - map range of kernel pages starts with zero offset
2077 * @vma: user vma to map to
2078 * @pages: pointer to array of source kernel pages
2079 * @num: number of pages in page array
2080 *
2081 * Similar to vm_map_pages(), except that it explicitly sets the offset
2082 * to 0. This function is intended for the drivers that did not consider
2083 * vm_pgoff.
2084 *
2085 * Context: Process context. Called by mmap handlers.
2086 * Return: 0 on success and error code otherwise.
2087 */
2088int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2089 unsigned long num)
2090{
2091 return __vm_map_pages(vma, pages, num, 0);
2092}
2093EXPORT_SYMBOL(vm_map_pages_zero);
2094
2095static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2096 pfn_t pfn, pgprot_t prot, bool mkwrite)
2097{
2098 struct mm_struct *mm = vma->vm_mm;
2099 pte_t *pte, entry;
2100 spinlock_t *ptl;
2101
2102 pte = get_locked_pte(mm, addr, &ptl);
2103 if (!pte)
2104 return VM_FAULT_OOM;
2105 if (!pte_none(*pte)) {
2106 if (mkwrite) {
2107 /*
2108 * For read faults on private mappings the PFN passed
2109 * in may not match the PFN we have mapped if the
2110 * mapped PFN is a writeable COW page. In the mkwrite
2111 * case we are creating a writable PTE for a shared
2112 * mapping and we expect the PFNs to match. If they
2113 * don't match, we are likely racing with block
2114 * allocation and mapping invalidation so just skip the
2115 * update.
2116 */
2117 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
2118 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
2119 goto out_unlock;
2120 }
2121 entry = pte_mkyoung(*pte);
2122 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2123 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2124 update_mmu_cache(vma, addr, pte);
2125 }
2126 goto out_unlock;
2127 }
2128
2129 /* Ok, finally just insert the thing.. */
2130 if (pfn_t_devmap(pfn))
2131 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2132 else
2133 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2134
2135 if (mkwrite) {
2136 entry = pte_mkyoung(entry);
2137 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2138 }
2139
2140 set_pte_at(mm, addr, pte, entry);
2141 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2142
2143out_unlock:
2144 pte_unmap_unlock(pte, ptl);
2145 return VM_FAULT_NOPAGE;
2146}
2147
2148/**
2149 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2150 * @vma: user vma to map to
2151 * @addr: target user address of this page
2152 * @pfn: source kernel pfn
2153 * @pgprot: pgprot flags for the inserted page
2154 *
2155 * This is exactly like vmf_insert_pfn(), except that it allows drivers
2156 * to override pgprot on a per-page basis.
2157 *
2158 * This only makes sense for IO mappings, and it makes no sense for
2159 * COW mappings. In general, using multiple vmas is preferable;
2160 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2161 * impractical.
2162 *
2163 * See vmf_insert_mixed_prot() for a discussion of the implication of using
2164 * a value of @pgprot different from that of @vma->vm_page_prot.
2165 *
2166 * Context: Process context. May allocate using %GFP_KERNEL.
2167 * Return: vm_fault_t value.
2168 */
2169vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2170 unsigned long pfn, pgprot_t pgprot)
2171{
2172 /*
2173 * Technically, architectures with pte_special can avoid all these
2174 * restrictions (same for remap_pfn_range). However we would like
2175 * consistency in testing and feature parity among all, so we should
2176 * try to keep these invariants in place for everybody.
2177 */
2178 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2179 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2180 (VM_PFNMAP|VM_MIXEDMAP));
2181 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2182 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2183
2184 if (addr < vma->vm_start || addr >= vma->vm_end)
2185 return VM_FAULT_SIGBUS;
2186
2187 if (!pfn_modify_allowed(pfn, pgprot))
2188 return VM_FAULT_SIGBUS;
2189
2190 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2191
2192 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2193 false);
2194}
2195EXPORT_SYMBOL(vmf_insert_pfn_prot);
2196
2197/**
2198 * vmf_insert_pfn - insert single pfn into user vma
2199 * @vma: user vma to map to
2200 * @addr: target user address of this page
2201 * @pfn: source kernel pfn
2202 *
2203 * Similar to vm_insert_page, this allows drivers to insert individual pages
2204 * they've allocated into a user vma. Same comments apply.
2205 *
2206 * This function should only be called from a vm_ops->fault handler, and
2207 * in that case the handler should return the result of this function.
2208 *
2209 * vma cannot be a COW mapping.
2210 *
2211 * As this is called only for pages that do not currently exist, we
2212 * do not need to flush old virtual caches or the TLB.
2213 *
2214 * Context: Process context. May allocate using %GFP_KERNEL.
2215 * Return: vm_fault_t value.
2216 */
2217vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2218 unsigned long pfn)
2219{
2220 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2221}
2222EXPORT_SYMBOL(vmf_insert_pfn);
2223
2224static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
2225{
2226 /* these checks mirror the abort conditions in vm_normal_page */
2227 if (vma->vm_flags & VM_MIXEDMAP)
2228 return true;
2229 if (pfn_t_devmap(pfn))
2230 return true;
2231 if (pfn_t_special(pfn))
2232 return true;
2233 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2234 return true;
2235 return false;
2236}
2237
2238static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2239 unsigned long addr, pfn_t pfn, pgprot_t pgprot,
2240 bool mkwrite)
2241{
2242 int err;
2243
2244 BUG_ON(!vm_mixed_ok(vma, pfn));
2245
2246 if (addr < vma->vm_start || addr >= vma->vm_end)
2247 return VM_FAULT_SIGBUS;
2248
2249 track_pfn_insert(vma, &pgprot, pfn);
2250
2251 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2252 return VM_FAULT_SIGBUS;
2253
2254 /*
2255 * If we don't have pte special, then we have to use the pfn_valid()
2256 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2257 * refcount the page if pfn_valid is true (hence insert_page rather
2258 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2259 * without pte special, it would there be refcounted as a normal page.
2260 */
2261 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2262 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2263 struct page *page;
2264
2265 /*
2266 * At this point we are committed to insert_page()
2267 * regardless of whether the caller specified flags that
2268 * result in pfn_t_has_page() == false.
2269 */
2270 page = pfn_to_page(pfn_t_to_pfn(pfn));
2271 err = insert_page(vma, addr, page, pgprot);
2272 } else {
2273 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2274 }
2275
2276 if (err == -ENOMEM)
2277 return VM_FAULT_OOM;
2278 if (err < 0 && err != -EBUSY)
2279 return VM_FAULT_SIGBUS;
2280
2281 return VM_FAULT_NOPAGE;
2282}
2283
2284/**
2285 * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
2286 * @vma: user vma to map to
2287 * @addr: target user address of this page
2288 * @pfn: source kernel pfn
2289 * @pgprot: pgprot flags for the inserted page
2290 *
2291 * This is exactly like vmf_insert_mixed(), except that it allows drivers
2292 * to override pgprot on a per-page basis.
2293 *
2294 * Typically this function should be used by drivers to set caching- and
2295 * encryption bits different than those of @vma->vm_page_prot, because
2296 * the caching- or encryption mode may not be known at mmap() time.
2297 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2298 * to set caching and encryption bits for those vmas (except for COW pages).
2299 * This is ensured by core vm only modifying these page table entries using
2300 * functions that don't touch caching- or encryption bits, using pte_modify()
2301 * if needed. (See for example mprotect()).
2302 * Also when new page-table entries are created, this is only done using the
2303 * fault() callback, and never using the value of vma->vm_page_prot,
2304 * except for page-table entries that point to anonymous pages as the result
2305 * of COW.
2306 *
2307 * Context: Process context. May allocate using %GFP_KERNEL.
2308 * Return: vm_fault_t value.
2309 */
2310vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
2311 pfn_t pfn, pgprot_t pgprot)
2312{
2313 return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
2314}
2315EXPORT_SYMBOL(vmf_insert_mixed_prot);
2316
2317vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2318 pfn_t pfn)
2319{
2320 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
2321}
2322EXPORT_SYMBOL(vmf_insert_mixed);
2323
2324/*
2325 * If the insertion of PTE failed because someone else already added a
2326 * different entry in the mean time, we treat that as success as we assume
2327 * the same entry was actually inserted.
2328 */
2329vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2330 unsigned long addr, pfn_t pfn)
2331{
2332 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
2333}
2334EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2335
2336/*
2337 * maps a range of physical memory into the requested pages. the old
2338 * mappings are removed. any references to nonexistent pages results
2339 * in null mappings (currently treated as "copy-on-access")
2340 */
2341static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2342 unsigned long addr, unsigned long end,
2343 unsigned long pfn, pgprot_t prot)
2344{
2345 pte_t *pte, *mapped_pte;
2346 spinlock_t *ptl;
2347 int err = 0;
2348
2349 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2350 if (!pte)
2351 return -ENOMEM;
2352 arch_enter_lazy_mmu_mode();
2353 do {
2354 BUG_ON(!pte_none(*pte));
2355 if (!pfn_modify_allowed(pfn, prot)) {
2356 err = -EACCES;
2357 break;
2358 }
2359 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2360 pfn++;
2361 } while (pte++, addr += PAGE_SIZE, addr != end);
2362 arch_leave_lazy_mmu_mode();
2363 pte_unmap_unlock(mapped_pte, ptl);
2364 return err;
2365}
2366
2367static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2368 unsigned long addr, unsigned long end,
2369 unsigned long pfn, pgprot_t prot)
2370{
2371 pmd_t *pmd;
2372 unsigned long next;
2373 int err;
2374
2375 pfn -= addr >> PAGE_SHIFT;
2376 pmd = pmd_alloc(mm, pud, addr);
2377 if (!pmd)
2378 return -ENOMEM;
2379 VM_BUG_ON(pmd_trans_huge(*pmd));
2380 do {
2381 next = pmd_addr_end(addr, end);
2382 err = remap_pte_range(mm, pmd, addr, next,
2383 pfn + (addr >> PAGE_SHIFT), prot);
2384 if (err)
2385 return err;
2386 } while (pmd++, addr = next, addr != end);
2387 return 0;
2388}
2389
2390static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2391 unsigned long addr, unsigned long end,
2392 unsigned long pfn, pgprot_t prot)
2393{
2394 pud_t *pud;
2395 unsigned long next;
2396 int err;
2397
2398 pfn -= addr >> PAGE_SHIFT;
2399 pud = pud_alloc(mm, p4d, addr);
2400 if (!pud)
2401 return -ENOMEM;
2402 do {
2403 next = pud_addr_end(addr, end);
2404 err = remap_pmd_range(mm, pud, addr, next,
2405 pfn + (addr >> PAGE_SHIFT), prot);
2406 if (err)
2407 return err;
2408 } while (pud++, addr = next, addr != end);
2409 return 0;
2410}
2411
2412static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2413 unsigned long addr, unsigned long end,
2414 unsigned long pfn, pgprot_t prot)
2415{
2416 p4d_t *p4d;
2417 unsigned long next;
2418 int err;
2419
2420 pfn -= addr >> PAGE_SHIFT;
2421 p4d = p4d_alloc(mm, pgd, addr);
2422 if (!p4d)
2423 return -ENOMEM;
2424 do {
2425 next = p4d_addr_end(addr, end);
2426 err = remap_pud_range(mm, p4d, addr, next,
2427 pfn + (addr >> PAGE_SHIFT), prot);
2428 if (err)
2429 return err;
2430 } while (p4d++, addr = next, addr != end);
2431 return 0;
2432}
2433
2434/*
2435 * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
2436 * must have pre-validated the caching bits of the pgprot_t.
2437 */
2438int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2439 unsigned long pfn, unsigned long size, pgprot_t prot)
2440{
2441 pgd_t *pgd;
2442 unsigned long next;
2443 unsigned long end = addr + PAGE_ALIGN(size);
2444 struct mm_struct *mm = vma->vm_mm;
2445 int err;
2446
2447 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2448 return -EINVAL;
2449
2450 /*
2451 * Physically remapped pages are special. Tell the
2452 * rest of the world about it:
2453 * VM_IO tells people not to look at these pages
2454 * (accesses can have side effects).
2455 * VM_PFNMAP tells the core MM that the base pages are just
2456 * raw PFN mappings, and do not have a "struct page" associated
2457 * with them.
2458 * VM_DONTEXPAND
2459 * Disable vma merging and expanding with mremap().
2460 * VM_DONTDUMP
2461 * Omit vma from core dump, even when VM_IO turned off.
2462 *
2463 * There's a horrible special case to handle copy-on-write
2464 * behaviour that some programs depend on. We mark the "original"
2465 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2466 * See vm_normal_page() for details.
2467 */
2468 if (is_cow_mapping(vma->vm_flags)) {
2469 if (addr != vma->vm_start || end != vma->vm_end)
2470 return -EINVAL;
2471 vma->vm_pgoff = pfn;
2472 }
2473
2474 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2475
2476 BUG_ON(addr >= end);
2477 pfn -= addr >> PAGE_SHIFT;
2478 pgd = pgd_offset(mm, addr);
2479 flush_cache_range(vma, addr, end);
2480 do {
2481 next = pgd_addr_end(addr, end);
2482 err = remap_p4d_range(mm, pgd, addr, next,
2483 pfn + (addr >> PAGE_SHIFT), prot);
2484 if (err)
2485 return err;
2486 } while (pgd++, addr = next, addr != end);
2487
2488 return 0;
2489}
2490
2491/**
2492 * remap_pfn_range - remap kernel memory to userspace
2493 * @vma: user vma to map to
2494 * @addr: target page aligned user address to start at
2495 * @pfn: page frame number of kernel physical memory address
2496 * @size: size of mapping area
2497 * @prot: page protection flags for this mapping
2498 *
2499 * Note: this is only safe if the mm semaphore is held when called.
2500 *
2501 * Return: %0 on success, negative error code otherwise.
2502 */
2503int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2504 unsigned long pfn, unsigned long size, pgprot_t prot)
2505{
2506 int err;
2507
2508 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2509 if (err)
2510 return -EINVAL;
2511
2512 err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2513 if (err)
2514 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2515 return err;
2516}
2517EXPORT_SYMBOL(remap_pfn_range);
2518
2519/**
2520 * vm_iomap_memory - remap memory to userspace
2521 * @vma: user vma to map to
2522 * @start: start of the physical memory to be mapped
2523 * @len: size of area
2524 *
2525 * This is a simplified io_remap_pfn_range() for common driver use. The
2526 * driver just needs to give us the physical memory range to be mapped,
2527 * we'll figure out the rest from the vma information.
2528 *
2529 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2530 * whatever write-combining details or similar.
2531 *
2532 * Return: %0 on success, negative error code otherwise.
2533 */
2534int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2535{
2536 unsigned long vm_len, pfn, pages;
2537
2538 /* Check that the physical memory area passed in looks valid */
2539 if (start + len < start)
2540 return -EINVAL;
2541 /*
2542 * You *really* shouldn't map things that aren't page-aligned,
2543 * but we've historically allowed it because IO memory might
2544 * just have smaller alignment.
2545 */
2546 len += start & ~PAGE_MASK;
2547 pfn = start >> PAGE_SHIFT;
2548 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2549 if (pfn + pages < pfn)
2550 return -EINVAL;
2551
2552 /* We start the mapping 'vm_pgoff' pages into the area */
2553 if (vma->vm_pgoff > pages)
2554 return -EINVAL;
2555 pfn += vma->vm_pgoff;
2556 pages -= vma->vm_pgoff;
2557
2558 /* Can we fit all of the mapping? */
2559 vm_len = vma->vm_end - vma->vm_start;
2560 if (vm_len >> PAGE_SHIFT > pages)
2561 return -EINVAL;
2562
2563 /* Ok, let it rip */
2564 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2565}
2566EXPORT_SYMBOL(vm_iomap_memory);
2567
2568static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2569 unsigned long addr, unsigned long end,
2570 pte_fn_t fn, void *data, bool create,
2571 pgtbl_mod_mask *mask)
2572{
2573 pte_t *pte, *mapped_pte;
2574 int err = 0;
2575 spinlock_t *ptl;
2576
2577 if (create) {
2578 mapped_pte = pte = (mm == &init_mm) ?
2579 pte_alloc_kernel_track(pmd, addr, mask) :
2580 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2581 if (!pte)
2582 return -ENOMEM;
2583 } else {
2584 mapped_pte = pte = (mm == &init_mm) ?
2585 pte_offset_kernel(pmd, addr) :
2586 pte_offset_map_lock(mm, pmd, addr, &ptl);
2587 }
2588
2589 BUG_ON(pmd_huge(*pmd));
2590
2591 arch_enter_lazy_mmu_mode();
2592
2593 if (fn) {
2594 do {
2595 if (create || !pte_none(*pte)) {
2596 err = fn(pte++, addr, data);
2597 if (err)
2598 break;
2599 }
2600 } while (addr += PAGE_SIZE, addr != end);
2601 }
2602 *mask |= PGTBL_PTE_MODIFIED;
2603
2604 arch_leave_lazy_mmu_mode();
2605
2606 if (mm != &init_mm)
2607 pte_unmap_unlock(mapped_pte, ptl);
2608 return err;
2609}
2610
2611static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2612 unsigned long addr, unsigned long end,
2613 pte_fn_t fn, void *data, bool create,
2614 pgtbl_mod_mask *mask)
2615{
2616 pmd_t *pmd;
2617 unsigned long next;
2618 int err = 0;
2619
2620 BUG_ON(pud_huge(*pud));
2621
2622 if (create) {
2623 pmd = pmd_alloc_track(mm, pud, addr, mask);
2624 if (!pmd)
2625 return -ENOMEM;
2626 } else {
2627 pmd = pmd_offset(pud, addr);
2628 }
2629 do {
2630 next = pmd_addr_end(addr, end);
2631 if (pmd_none(*pmd) && !create)
2632 continue;
2633 if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2634 return -EINVAL;
2635 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2636 if (!create)
2637 continue;
2638 pmd_clear_bad(pmd);
2639 }
2640 err = apply_to_pte_range(mm, pmd, addr, next,
2641 fn, data, create, mask);
2642 if (err)
2643 break;
2644 } while (pmd++, addr = next, addr != end);
2645
2646 return err;
2647}
2648
2649static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2650 unsigned long addr, unsigned long end,
2651 pte_fn_t fn, void *data, bool create,
2652 pgtbl_mod_mask *mask)
2653{
2654 pud_t *pud;
2655 unsigned long next;
2656 int err = 0;
2657
2658 if (create) {
2659 pud = pud_alloc_track(mm, p4d, addr, mask);
2660 if (!pud)
2661 return -ENOMEM;
2662 } else {
2663 pud = pud_offset(p4d, addr);
2664 }
2665 do {
2666 next = pud_addr_end(addr, end);
2667 if (pud_none(*pud) && !create)
2668 continue;
2669 if (WARN_ON_ONCE(pud_leaf(*pud)))
2670 return -EINVAL;
2671 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2672 if (!create)
2673 continue;
2674 pud_clear_bad(pud);
2675 }
2676 err = apply_to_pmd_range(mm, pud, addr, next,
2677 fn, data, create, mask);
2678 if (err)
2679 break;
2680 } while (pud++, addr = next, addr != end);
2681
2682 return err;
2683}
2684
2685static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2686 unsigned long addr, unsigned long end,
2687 pte_fn_t fn, void *data, bool create,
2688 pgtbl_mod_mask *mask)
2689{
2690 p4d_t *p4d;
2691 unsigned long next;
2692 int err = 0;
2693
2694 if (create) {
2695 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2696 if (!p4d)
2697 return -ENOMEM;
2698 } else {
2699 p4d = p4d_offset(pgd, addr);
2700 }
2701 do {
2702 next = p4d_addr_end(addr, end);
2703 if (p4d_none(*p4d) && !create)
2704 continue;
2705 if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2706 return -EINVAL;
2707 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2708 if (!create)
2709 continue;
2710 p4d_clear_bad(p4d);
2711 }
2712 err = apply_to_pud_range(mm, p4d, addr, next,
2713 fn, data, create, mask);
2714 if (err)
2715 break;
2716 } while (p4d++, addr = next, addr != end);
2717
2718 return err;
2719}
2720
2721static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2722 unsigned long size, pte_fn_t fn,
2723 void *data, bool create)
2724{
2725 pgd_t *pgd;
2726 unsigned long start = addr, next;
2727 unsigned long end = addr + size;
2728 pgtbl_mod_mask mask = 0;
2729 int err = 0;
2730
2731 if (WARN_ON(addr >= end))
2732 return -EINVAL;
2733
2734 pgd = pgd_offset(mm, addr);
2735 do {
2736 next = pgd_addr_end(addr, end);
2737 if (pgd_none(*pgd) && !create)
2738 continue;
2739 if (WARN_ON_ONCE(pgd_leaf(*pgd)))
2740 return -EINVAL;
2741 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2742 if (!create)
2743 continue;
2744 pgd_clear_bad(pgd);
2745 }
2746 err = apply_to_p4d_range(mm, pgd, addr, next,
2747 fn, data, create, &mask);
2748 if (err)
2749 break;
2750 } while (pgd++, addr = next, addr != end);
2751
2752 if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2753 arch_sync_kernel_mappings(start, start + size);
2754
2755 return err;
2756}
2757
2758/*
2759 * Scan a region of virtual memory, filling in page tables as necessary
2760 * and calling a provided function on each leaf page table.
2761 */
2762int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2763 unsigned long size, pte_fn_t fn, void *data)
2764{
2765 return __apply_to_page_range(mm, addr, size, fn, data, true);
2766}
2767EXPORT_SYMBOL_GPL(apply_to_page_range);
2768
2769/*
2770 * Scan a region of virtual memory, calling a provided function on
2771 * each leaf page table where it exists.
2772 *
2773 * Unlike apply_to_page_range, this does _not_ fill in page tables
2774 * where they are absent.
2775 */
2776int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
2777 unsigned long size, pte_fn_t fn, void *data)
2778{
2779 return __apply_to_page_range(mm, addr, size, fn, data, false);
2780}
2781EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
2782
2783/*
2784 * handle_pte_fault chooses page fault handler according to an entry which was
2785 * read non-atomically. Before making any commitment, on those architectures
2786 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2787 * parts, do_swap_page must check under lock before unmapping the pte and
2788 * proceeding (but do_wp_page is only called after already making such a check;
2789 * and do_anonymous_page can safely check later on).
2790 */
2791static inline int pte_unmap_same(struct vm_fault *vmf)
2792{
2793 int same = 1;
2794#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2795 if (sizeof(pte_t) > sizeof(unsigned long)) {
2796 spinlock_t *ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
2797 spin_lock(ptl);
2798 same = pte_same(*vmf->pte, vmf->orig_pte);
2799 spin_unlock(ptl);
2800 }
2801#endif
2802 pte_unmap(vmf->pte);
2803 vmf->pte = NULL;
2804 return same;
2805}
2806
2807/*
2808 * Return:
2809 * 0: copied succeeded
2810 * -EHWPOISON: copy failed due to hwpoison in source page
2811 * -EAGAIN: copied failed (some other reason)
2812 */
2813static inline int __wp_page_copy_user(struct page *dst, struct page *src,
2814 struct vm_fault *vmf)
2815{
2816 int ret;
2817 void *kaddr;
2818 void __user *uaddr;
2819 bool locked = false;
2820 struct vm_area_struct *vma = vmf->vma;
2821 struct mm_struct *mm = vma->vm_mm;
2822 unsigned long addr = vmf->address;
2823
2824 if (likely(src)) {
2825 if (copy_mc_user_highpage(dst, src, addr, vma)) {
2826 memory_failure_queue(page_to_pfn(src), 0);
2827 return -EHWPOISON;
2828 }
2829 return 0;
2830 }
2831
2832 /*
2833 * If the source page was a PFN mapping, we don't have
2834 * a "struct page" for it. We do a best-effort copy by
2835 * just copying from the original user address. If that
2836 * fails, we just zero-fill it. Live with it.
2837 */
2838 kaddr = kmap_atomic(dst);
2839 uaddr = (void __user *)(addr & PAGE_MASK);
2840
2841 /*
2842 * On architectures with software "accessed" bits, we would
2843 * take a double page fault, so mark it accessed here.
2844 */
2845 if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
2846 pte_t entry;
2847
2848 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2849 locked = true;
2850 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2851 /*
2852 * Other thread has already handled the fault
2853 * and update local tlb only
2854 */
2855 update_mmu_tlb(vma, addr, vmf->pte);
2856 ret = -EAGAIN;
2857 goto pte_unlock;
2858 }
2859
2860 entry = pte_mkyoung(vmf->orig_pte);
2861 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2862 update_mmu_cache(vma, addr, vmf->pte);
2863 }
2864
2865 /*
2866 * This really shouldn't fail, because the page is there
2867 * in the page tables. But it might just be unreadable,
2868 * in which case we just give up and fill the result with
2869 * zeroes.
2870 */
2871 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2872 if (locked)
2873 goto warn;
2874
2875 /* Re-validate under PTL if the page is still mapped */
2876 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2877 locked = true;
2878 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2879 /* The PTE changed under us, update local tlb */
2880 update_mmu_tlb(vma, addr, vmf->pte);
2881 ret = -EAGAIN;
2882 goto pte_unlock;
2883 }
2884
2885 /*
2886 * The same page can be mapped back since last copy attempt.
2887 * Try to copy again under PTL.
2888 */
2889 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2890 /*
2891 * Give a warn in case there can be some obscure
2892 * use-case
2893 */
2894warn:
2895 WARN_ON_ONCE(1);
2896 clear_page(kaddr);
2897 }
2898 }
2899
2900 ret = 0;
2901
2902pte_unlock:
2903 if (locked)
2904 pte_unmap_unlock(vmf->pte, vmf->ptl);
2905 kunmap_atomic(kaddr);
2906 flush_dcache_page(dst);
2907
2908 return ret;
2909}
2910
2911static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2912{
2913 struct file *vm_file = vma->vm_file;
2914
2915 if (vm_file)
2916 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2917
2918 /*
2919 * Special mappings (e.g. VDSO) do not have any file so fake
2920 * a default GFP_KERNEL for them.
2921 */
2922 return GFP_KERNEL;
2923}
2924
2925/*
2926 * Notify the address space that the page is about to become writable so that
2927 * it can prohibit this or wait for the page to get into an appropriate state.
2928 *
2929 * We do this without the lock held, so that it can sleep if it needs to.
2930 */
2931static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2932{
2933 vm_fault_t ret;
2934 struct page *page = vmf->page;
2935 unsigned int old_flags = vmf->flags;
2936
2937 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2938
2939 if (vmf->vma->vm_file &&
2940 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2941 return VM_FAULT_SIGBUS;
2942
2943 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2944 /* Restore original flags so that caller is not surprised */
2945 vmf->flags = old_flags;
2946 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2947 return ret;
2948 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2949 lock_page(page);
2950 if (!page->mapping) {
2951 unlock_page(page);
2952 return 0; /* retry */
2953 }
2954 ret |= VM_FAULT_LOCKED;
2955 } else
2956 VM_BUG_ON_PAGE(!PageLocked(page), page);
2957 return ret;
2958}
2959
2960/*
2961 * Handle dirtying of a page in shared file mapping on a write fault.
2962 *
2963 * The function expects the page to be locked and unlocks it.
2964 */
2965static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
2966{
2967 struct vm_area_struct *vma = vmf->vma;
2968 struct address_space *mapping;
2969 struct page *page = vmf->page;
2970 bool dirtied;
2971 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2972
2973 dirtied = set_page_dirty(page);
2974 VM_BUG_ON_PAGE(PageAnon(page), page);
2975 /*
2976 * Take a local copy of the address_space - page.mapping may be zeroed
2977 * by truncate after unlock_page(). The address_space itself remains
2978 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2979 * release semantics to prevent the compiler from undoing this copying.
2980 */
2981 mapping = page_rmapping(page);
2982 unlock_page(page);
2983
2984 if (!page_mkwrite)
2985 file_update_time(vma->vm_file);
2986
2987 /*
2988 * Throttle page dirtying rate down to writeback speed.
2989 *
2990 * mapping may be NULL here because some device drivers do not
2991 * set page.mapping but still dirty their pages
2992 *
2993 * Drop the mmap_lock before waiting on IO, if we can. The file
2994 * is pinning the mapping, as per above.
2995 */
2996 if ((dirtied || page_mkwrite) && mapping) {
2997 struct file *fpin;
2998
2999 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
3000 balance_dirty_pages_ratelimited(mapping);
3001 if (fpin) {
3002 fput(fpin);
3003 return VM_FAULT_COMPLETED;
3004 }
3005 }
3006
3007 return 0;
3008}
3009
3010/*
3011 * Handle write page faults for pages that can be reused in the current vma
3012 *
3013 * This can happen either due to the mapping being with the VM_SHARED flag,
3014 * or due to us being the last reference standing to the page. In either
3015 * case, all we need to do here is to mark the page as writable and update
3016 * any related book-keeping.
3017 */
3018static inline void wp_page_reuse(struct vm_fault *vmf)
3019 __releases(vmf->ptl)
3020{
3021 struct vm_area_struct *vma = vmf->vma;
3022 struct page *page = vmf->page;
3023 pte_t entry;
3024
3025 VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE));
3026 VM_BUG_ON(page && PageAnon(page) && !PageAnonExclusive(page));
3027
3028 /*
3029 * Clear the pages cpupid information as the existing
3030 * information potentially belongs to a now completely
3031 * unrelated process.
3032 */
3033 if (page)
3034 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
3035
3036 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3037 entry = pte_mkyoung(vmf->orig_pte);
3038 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3039 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
3040 update_mmu_cache(vma, vmf->address, vmf->pte);
3041 pte_unmap_unlock(vmf->pte, vmf->ptl);
3042 count_vm_event(PGREUSE);
3043}
3044
3045/*
3046 * Handle the case of a page which we actually need to copy to a new page,
3047 * either due to COW or unsharing.
3048 *
3049 * Called with mmap_lock locked and the old page referenced, but
3050 * without the ptl held.
3051 *
3052 * High level logic flow:
3053 *
3054 * - Allocate a page, copy the content of the old page to the new one.
3055 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
3056 * - Take the PTL. If the pte changed, bail out and release the allocated page
3057 * - If the pte is still the way we remember it, update the page table and all
3058 * relevant references. This includes dropping the reference the page-table
3059 * held to the old page, as well as updating the rmap.
3060 * - In any case, unlock the PTL and drop the reference we took to the old page.
3061 */
3062static vm_fault_t wp_page_copy(struct vm_fault *vmf)
3063{
3064 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3065 struct vm_area_struct *vma = vmf->vma;
3066 struct mm_struct *mm = vma->vm_mm;
3067 struct page *old_page = vmf->page;
3068 struct page *new_page = NULL;
3069 pte_t entry;
3070 int page_copied = 0;
3071 struct mmu_notifier_range range;
3072 int ret;
3073
3074 delayacct_wpcopy_start();
3075
3076 if (unlikely(anon_vma_prepare(vma)))
3077 goto oom;
3078
3079 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
3080 new_page = alloc_zeroed_user_highpage_movable(vma,
3081 vmf->address);
3082 if (!new_page)
3083 goto oom;
3084 } else {
3085 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3086 vmf->address);
3087 if (!new_page)
3088 goto oom;
3089
3090 ret = __wp_page_copy_user(new_page, old_page, vmf);
3091 if (ret) {
3092 /*
3093 * COW failed, if the fault was solved by other,
3094 * it's fine. If not, userspace would re-fault on
3095 * the same address and we will handle the fault
3096 * from the second attempt.
3097 * The -EHWPOISON case will not be retried.
3098 */
3099 put_page(new_page);
3100 if (old_page)
3101 put_page(old_page);
3102
3103 delayacct_wpcopy_end();
3104 return ret == -EHWPOISON ? VM_FAULT_HWPOISON : 0;
3105 }
3106 kmsan_copy_page_meta(new_page, old_page);
3107 }
3108
3109 if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL))
3110 goto oom_free_new;
3111 cgroup_throttle_swaprate(new_page, GFP_KERNEL);
3112
3113 __SetPageUptodate(new_page);
3114
3115 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
3116 vmf->address & PAGE_MASK,
3117 (vmf->address & PAGE_MASK) + PAGE_SIZE);
3118 mmu_notifier_invalidate_range_start(&range);
3119
3120 /*
3121 * Re-check the pte - we dropped the lock
3122 */
3123 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3124 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
3125 if (old_page) {
3126 if (!PageAnon(old_page)) {
3127 dec_mm_counter(mm, mm_counter_file(old_page));
3128 inc_mm_counter(mm, MM_ANONPAGES);
3129 }
3130 } else {
3131 inc_mm_counter(mm, MM_ANONPAGES);
3132 }
3133 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3134 entry = mk_pte(new_page, vma->vm_page_prot);
3135 entry = pte_sw_mkyoung(entry);
3136 if (unlikely(unshare)) {
3137 if (pte_soft_dirty(vmf->orig_pte))
3138 entry = pte_mksoft_dirty(entry);
3139 if (pte_uffd_wp(vmf->orig_pte))
3140 entry = pte_mkuffd_wp(entry);
3141 } else {
3142 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3143 }
3144
3145 /*
3146 * Clear the pte entry and flush it first, before updating the
3147 * pte with the new entry, to keep TLBs on different CPUs in
3148 * sync. This code used to set the new PTE then flush TLBs, but
3149 * that left a window where the new PTE could be loaded into
3150 * some TLBs while the old PTE remains in others.
3151 */
3152 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
3153 page_add_new_anon_rmap(new_page, vma, vmf->address);
3154 lru_cache_add_inactive_or_unevictable(new_page, vma);
3155 /*
3156 * We call the notify macro here because, when using secondary
3157 * mmu page tables (such as kvm shadow page tables), we want the
3158 * new page to be mapped directly into the secondary page table.
3159 */
3160 BUG_ON(unshare && pte_write(entry));
3161 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
3162 update_mmu_cache(vma, vmf->address, vmf->pte);
3163 if (old_page) {
3164 /*
3165 * Only after switching the pte to the new page may
3166 * we remove the mapcount here. Otherwise another
3167 * process may come and find the rmap count decremented
3168 * before the pte is switched to the new page, and
3169 * "reuse" the old page writing into it while our pte
3170 * here still points into it and can be read by other
3171 * threads.
3172 *
3173 * The critical issue is to order this
3174 * page_remove_rmap with the ptp_clear_flush above.
3175 * Those stores are ordered by (if nothing else,)
3176 * the barrier present in the atomic_add_negative
3177 * in page_remove_rmap.
3178 *
3179 * Then the TLB flush in ptep_clear_flush ensures that
3180 * no process can access the old page before the
3181 * decremented mapcount is visible. And the old page
3182 * cannot be reused until after the decremented
3183 * mapcount is visible. So transitively, TLBs to
3184 * old page will be flushed before it can be reused.
3185 */
3186 page_remove_rmap(old_page, vma, false);
3187 }
3188
3189 /* Free the old page.. */
3190 new_page = old_page;
3191 page_copied = 1;
3192 } else {
3193 update_mmu_tlb(vma, vmf->address, vmf->pte);
3194 }
3195
3196 if (new_page)
3197 put_page(new_page);
3198
3199 pte_unmap_unlock(vmf->pte, vmf->ptl);
3200 /*
3201 * No need to double call mmu_notifier->invalidate_range() callback as
3202 * the above ptep_clear_flush_notify() did already call it.
3203 */
3204 mmu_notifier_invalidate_range_only_end(&range);
3205 if (old_page) {
3206 if (page_copied)
3207 free_swap_cache(old_page);
3208 put_page(old_page);
3209 }
3210
3211 delayacct_wpcopy_end();
3212 return 0;
3213oom_free_new:
3214 put_page(new_page);
3215oom:
3216 if (old_page)
3217 put_page(old_page);
3218
3219 delayacct_wpcopy_end();
3220 return VM_FAULT_OOM;
3221}
3222
3223/**
3224 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3225 * writeable once the page is prepared
3226 *
3227 * @vmf: structure describing the fault
3228 *
3229 * This function handles all that is needed to finish a write page fault in a
3230 * shared mapping due to PTE being read-only once the mapped page is prepared.
3231 * It handles locking of PTE and modifying it.
3232 *
3233 * The function expects the page to be locked or other protection against
3234 * concurrent faults / writeback (such as DAX radix tree locks).
3235 *
3236 * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3237 * we acquired PTE lock.
3238 */
3239vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
3240{
3241 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3242 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3243 &vmf->ptl);
3244 /*
3245 * We might have raced with another page fault while we released the
3246 * pte_offset_map_lock.
3247 */
3248 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
3249 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3250 pte_unmap_unlock(vmf->pte, vmf->ptl);
3251 return VM_FAULT_NOPAGE;
3252 }
3253 wp_page_reuse(vmf);
3254 return 0;
3255}
3256
3257/*
3258 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3259 * mapping
3260 */
3261static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3262{
3263 struct vm_area_struct *vma = vmf->vma;
3264
3265 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3266 vm_fault_t ret;
3267
3268 pte_unmap_unlock(vmf->pte, vmf->ptl);
3269 vmf->flags |= FAULT_FLAG_MKWRITE;
3270 ret = vma->vm_ops->pfn_mkwrite(vmf);
3271 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3272 return ret;
3273 return finish_mkwrite_fault(vmf);
3274 }
3275 wp_page_reuse(vmf);
3276 return 0;
3277}
3278
3279static vm_fault_t wp_page_shared(struct vm_fault *vmf)
3280 __releases(vmf->ptl)
3281{
3282 struct vm_area_struct *vma = vmf->vma;
3283 vm_fault_t ret = 0;
3284
3285 get_page(vmf->page);
3286
3287 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3288 vm_fault_t tmp;
3289
3290 pte_unmap_unlock(vmf->pte, vmf->ptl);
3291 tmp = do_page_mkwrite(vmf);
3292 if (unlikely(!tmp || (tmp &
3293 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3294 put_page(vmf->page);
3295 return tmp;
3296 }
3297 tmp = finish_mkwrite_fault(vmf);
3298 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3299 unlock_page(vmf->page);
3300 put_page(vmf->page);
3301 return tmp;
3302 }
3303 } else {
3304 wp_page_reuse(vmf);
3305 lock_page(vmf->page);
3306 }
3307 ret |= fault_dirty_shared_page(vmf);
3308 put_page(vmf->page);
3309
3310 return ret;
3311}
3312
3313/*
3314 * This routine handles present pages, when
3315 * * users try to write to a shared page (FAULT_FLAG_WRITE)
3316 * * GUP wants to take a R/O pin on a possibly shared anonymous page
3317 * (FAULT_FLAG_UNSHARE)
3318 *
3319 * It is done by copying the page to a new address and decrementing the
3320 * shared-page counter for the old page.
3321 *
3322 * Note that this routine assumes that the protection checks have been
3323 * done by the caller (the low-level page fault routine in most cases).
3324 * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've
3325 * done any necessary COW.
3326 *
3327 * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even
3328 * though the page will change only once the write actually happens. This
3329 * avoids a few races, and potentially makes it more efficient.
3330 *
3331 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3332 * but allow concurrent faults), with pte both mapped and locked.
3333 * We return with mmap_lock still held, but pte unmapped and unlocked.
3334 */
3335static vm_fault_t do_wp_page(struct vm_fault *vmf)
3336 __releases(vmf->ptl)
3337{
3338 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3339 struct vm_area_struct *vma = vmf->vma;
3340 struct folio *folio = NULL;
3341
3342 if (likely(!unshare)) {
3343 if (userfaultfd_pte_wp(vma, *vmf->pte)) {
3344 pte_unmap_unlock(vmf->pte, vmf->ptl);
3345 return handle_userfault(vmf, VM_UFFD_WP);
3346 }
3347
3348 /*
3349 * Userfaultfd write-protect can defer flushes. Ensure the TLB
3350 * is flushed in this case before copying.
3351 */
3352 if (unlikely(userfaultfd_wp(vmf->vma) &&
3353 mm_tlb_flush_pending(vmf->vma->vm_mm)))
3354 flush_tlb_page(vmf->vma, vmf->address);
3355 }
3356
3357 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3358
3359 /*
3360 * Shared mapping: we are guaranteed to have VM_WRITE and
3361 * FAULT_FLAG_WRITE set at this point.
3362 */
3363 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
3364 /*
3365 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3366 * VM_PFNMAP VMA.
3367 *
3368 * We should not cow pages in a shared writeable mapping.
3369 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3370 */
3371 if (!vmf->page)
3372 return wp_pfn_shared(vmf);
3373 return wp_page_shared(vmf);
3374 }
3375
3376 if (vmf->page)
3377 folio = page_folio(vmf->page);
3378
3379 /*
3380 * Private mapping: create an exclusive anonymous page copy if reuse
3381 * is impossible. We might miss VM_WRITE for FOLL_FORCE handling.
3382 */
3383 if (folio && folio_test_anon(folio)) {
3384 /*
3385 * If the page is exclusive to this process we must reuse the
3386 * page without further checks.
3387 */
3388 if (PageAnonExclusive(vmf->page))
3389 goto reuse;
3390
3391 /*
3392 * We have to verify under folio lock: these early checks are
3393 * just an optimization to avoid locking the folio and freeing
3394 * the swapcache if there is little hope that we can reuse.
3395 *
3396 * KSM doesn't necessarily raise the folio refcount.
3397 */
3398 if (folio_test_ksm(folio) || folio_ref_count(folio) > 3)
3399 goto copy;
3400 if (!folio_test_lru(folio))
3401 /*
3402 * Note: We cannot easily detect+handle references from
3403 * remote LRU pagevecs or references to LRU folios.
3404 */
3405 lru_add_drain();
3406 if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio))
3407 goto copy;
3408 if (!folio_trylock(folio))
3409 goto copy;
3410 if (folio_test_swapcache(folio))
3411 folio_free_swap(folio);
3412 if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) {
3413 folio_unlock(folio);
3414 goto copy;
3415 }
3416 /*
3417 * Ok, we've got the only folio reference from our mapping
3418 * and the folio is locked, it's dark out, and we're wearing
3419 * sunglasses. Hit it.
3420 */
3421 page_move_anon_rmap(vmf->page, vma);
3422 folio_unlock(folio);
3423reuse:
3424 if (unlikely(unshare)) {
3425 pte_unmap_unlock(vmf->pte, vmf->ptl);
3426 return 0;
3427 }
3428 wp_page_reuse(vmf);
3429 return 0;
3430 }
3431copy:
3432 /*
3433 * Ok, we need to copy. Oh, well..
3434 */
3435 if (folio)
3436 folio_get(folio);
3437
3438 pte_unmap_unlock(vmf->pte, vmf->ptl);
3439#ifdef CONFIG_KSM
3440 if (folio && folio_test_ksm(folio))
3441 count_vm_event(COW_KSM);
3442#endif
3443 return wp_page_copy(vmf);
3444}
3445
3446static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3447 unsigned long start_addr, unsigned long end_addr,
3448 struct zap_details *details)
3449{
3450 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3451}
3452
3453static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3454 pgoff_t first_index,
3455 pgoff_t last_index,
3456 struct zap_details *details)
3457{
3458 struct vm_area_struct *vma;
3459 pgoff_t vba, vea, zba, zea;
3460
3461 vma_interval_tree_foreach(vma, root, first_index, last_index) {
3462 vba = vma->vm_pgoff;
3463 vea = vba + vma_pages(vma) - 1;
3464 zba = max(first_index, vba);
3465 zea = min(last_index, vea);
3466
3467 unmap_mapping_range_vma(vma,
3468 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3469 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3470 details);
3471 }
3472}
3473
3474/**
3475 * unmap_mapping_folio() - Unmap single folio from processes.
3476 * @folio: The locked folio to be unmapped.
3477 *
3478 * Unmap this folio from any userspace process which still has it mmaped.
3479 * Typically, for efficiency, the range of nearby pages has already been
3480 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
3481 * truncation or invalidation holds the lock on a folio, it may find that
3482 * the page has been remapped again: and then uses unmap_mapping_folio()
3483 * to unmap it finally.
3484 */
3485void unmap_mapping_folio(struct folio *folio)
3486{
3487 struct address_space *mapping = folio->mapping;
3488 struct zap_details details = { };
3489 pgoff_t first_index;
3490 pgoff_t last_index;
3491
3492 VM_BUG_ON(!folio_test_locked(folio));
3493
3494 first_index = folio->index;
3495 last_index = folio->index + folio_nr_pages(folio) - 1;
3496
3497 details.even_cows = false;
3498 details.single_folio = folio;
3499 details.zap_flags = ZAP_FLAG_DROP_MARKER;
3500
3501 i_mmap_lock_read(mapping);
3502 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3503 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3504 last_index, &details);
3505 i_mmap_unlock_read(mapping);
3506}
3507
3508/**
3509 * unmap_mapping_pages() - Unmap pages from processes.
3510 * @mapping: The address space containing pages to be unmapped.
3511 * @start: Index of first page to be unmapped.
3512 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3513 * @even_cows: Whether to unmap even private COWed pages.
3514 *
3515 * Unmap the pages in this address space from any userspace process which
3516 * has them mmaped. Generally, you want to remove COWed pages as well when
3517 * a file is being truncated, but not when invalidating pages from the page
3518 * cache.
3519 */
3520void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3521 pgoff_t nr, bool even_cows)
3522{
3523 struct zap_details details = { };
3524 pgoff_t first_index = start;
3525 pgoff_t last_index = start + nr - 1;
3526
3527 details.even_cows = even_cows;
3528 if (last_index < first_index)
3529 last_index = ULONG_MAX;
3530
3531 i_mmap_lock_read(mapping);
3532 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3533 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3534 last_index, &details);
3535 i_mmap_unlock_read(mapping);
3536}
3537EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3538
3539/**
3540 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3541 * address_space corresponding to the specified byte range in the underlying
3542 * file.
3543 *
3544 * @mapping: the address space containing mmaps to be unmapped.
3545 * @holebegin: byte in first page to unmap, relative to the start of
3546 * the underlying file. This will be rounded down to a PAGE_SIZE
3547 * boundary. Note that this is different from truncate_pagecache(), which
3548 * must keep the partial page. In contrast, we must get rid of
3549 * partial pages.
3550 * @holelen: size of prospective hole in bytes. This will be rounded
3551 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3552 * end of the file.
3553 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3554 * but 0 when invalidating pagecache, don't throw away private data.
3555 */
3556void unmap_mapping_range(struct address_space *mapping,
3557 loff_t const holebegin, loff_t const holelen, int even_cows)
3558{
3559 pgoff_t hba = holebegin >> PAGE_SHIFT;
3560 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3561
3562 /* Check for overflow. */
3563 if (sizeof(holelen) > sizeof(hlen)) {
3564 long long holeend =
3565 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3566 if (holeend & ~(long long)ULONG_MAX)
3567 hlen = ULONG_MAX - hba + 1;
3568 }
3569
3570 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3571}
3572EXPORT_SYMBOL(unmap_mapping_range);
3573
3574/*
3575 * Restore a potential device exclusive pte to a working pte entry
3576 */
3577static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3578{
3579 struct folio *folio = page_folio(vmf->page);
3580 struct vm_area_struct *vma = vmf->vma;
3581 struct mmu_notifier_range range;
3582
3583 if (!folio_lock_or_retry(folio, vma->vm_mm, vmf->flags))
3584 return VM_FAULT_RETRY;
3585 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
3586 vma->vm_mm, vmf->address & PAGE_MASK,
3587 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3588 mmu_notifier_invalidate_range_start(&range);
3589
3590 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3591 &vmf->ptl);
3592 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3593 restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
3594
3595 pte_unmap_unlock(vmf->pte, vmf->ptl);
3596 folio_unlock(folio);
3597
3598 mmu_notifier_invalidate_range_end(&range);
3599 return 0;
3600}
3601
3602static inline bool should_try_to_free_swap(struct folio *folio,
3603 struct vm_area_struct *vma,
3604 unsigned int fault_flags)
3605{
3606 if (!folio_test_swapcache(folio))
3607 return false;
3608 if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
3609 folio_test_mlocked(folio))
3610 return true;
3611 /*
3612 * If we want to map a page that's in the swapcache writable, we
3613 * have to detect via the refcount if we're really the exclusive
3614 * user. Try freeing the swapcache to get rid of the swapcache
3615 * reference only in case it's likely that we'll be the exlusive user.
3616 */
3617 return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
3618 folio_ref_count(folio) == 2;
3619}
3620
3621static vm_fault_t pte_marker_clear(struct vm_fault *vmf)
3622{
3623 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
3624 vmf->address, &vmf->ptl);
3625 /*
3626 * Be careful so that we will only recover a special uffd-wp pte into a
3627 * none pte. Otherwise it means the pte could have changed, so retry.
3628 *
3629 * This should also cover the case where e.g. the pte changed
3630 * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_SWAPIN_ERROR.
3631 * So is_pte_marker() check is not enough to safely drop the pte.
3632 */
3633 if (pte_same(vmf->orig_pte, *vmf->pte))
3634 pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte);
3635 pte_unmap_unlock(vmf->pte, vmf->ptl);
3636 return 0;
3637}
3638
3639/*
3640 * This is actually a page-missing access, but with uffd-wp special pte
3641 * installed. It means this pte was wr-protected before being unmapped.
3642 */
3643static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf)
3644{
3645 /*
3646 * Just in case there're leftover special ptes even after the region
3647 * got unregistered - we can simply clear them. We can also do that
3648 * proactively when e.g. when we do UFFDIO_UNREGISTER upon some uffd-wp
3649 * ranges, but it should be more efficient to be done lazily here.
3650 */
3651 if (unlikely(!userfaultfd_wp(vmf->vma) || vma_is_anonymous(vmf->vma)))
3652 return pte_marker_clear(vmf);
3653
3654 /* do_fault() can handle pte markers too like none pte */
3655 return do_fault(vmf);
3656}
3657
3658static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
3659{
3660 swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte);
3661 unsigned long marker = pte_marker_get(entry);
3662
3663 /*
3664 * PTE markers should never be empty. If anything weird happened,
3665 * the best thing to do is to kill the process along with its mm.
3666 */
3667 if (WARN_ON_ONCE(!marker))
3668 return VM_FAULT_SIGBUS;
3669
3670 /* Higher priority than uffd-wp when data corrupted */
3671 if (marker & PTE_MARKER_SWAPIN_ERROR)
3672 return VM_FAULT_SIGBUS;
3673
3674 if (pte_marker_entry_uffd_wp(entry))
3675 return pte_marker_handle_uffd_wp(vmf);
3676
3677 /* This is an unknown pte marker */
3678 return VM_FAULT_SIGBUS;
3679}
3680
3681/*
3682 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3683 * but allow concurrent faults), and pte mapped but not yet locked.
3684 * We return with pte unmapped and unlocked.
3685 *
3686 * We return with the mmap_lock locked or unlocked in the same cases
3687 * as does filemap_fault().
3688 */
3689vm_fault_t do_swap_page(struct vm_fault *vmf)
3690{
3691 struct vm_area_struct *vma = vmf->vma;
3692 struct folio *swapcache, *folio = NULL;
3693 struct page *page;
3694 struct swap_info_struct *si = NULL;
3695 rmap_t rmap_flags = RMAP_NONE;
3696 bool exclusive = false;
3697 swp_entry_t entry;
3698 pte_t pte;
3699 int locked;
3700 vm_fault_t ret = 0;
3701 void *shadow = NULL;
3702
3703 if (!pte_unmap_same(vmf))
3704 goto out;
3705
3706 entry = pte_to_swp_entry(vmf->orig_pte);
3707 if (unlikely(non_swap_entry(entry))) {
3708 if (is_migration_entry(entry)) {
3709 migration_entry_wait(vma->vm_mm, vmf->pmd,
3710 vmf->address);
3711 } else if (is_device_exclusive_entry(entry)) {
3712 vmf->page = pfn_swap_entry_to_page(entry);
3713 ret = remove_device_exclusive_entry(vmf);
3714 } else if (is_device_private_entry(entry)) {
3715 vmf->page = pfn_swap_entry_to_page(entry);
3716 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3717 vmf->address, &vmf->ptl);
3718 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3719 spin_unlock(vmf->ptl);
3720 goto out;
3721 }
3722
3723 /*
3724 * Get a page reference while we know the page can't be
3725 * freed.
3726 */
3727 get_page(vmf->page);
3728 pte_unmap_unlock(vmf->pte, vmf->ptl);
3729 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
3730 put_page(vmf->page);
3731 } else if (is_hwpoison_entry(entry)) {
3732 ret = VM_FAULT_HWPOISON;
3733 } else if (is_pte_marker_entry(entry)) {
3734 ret = handle_pte_marker(vmf);
3735 } else {
3736 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3737 ret = VM_FAULT_SIGBUS;
3738 }
3739 goto out;
3740 }
3741
3742 /* Prevent swapoff from happening to us. */
3743 si = get_swap_device(entry);
3744 if (unlikely(!si))
3745 goto out;
3746
3747 folio = swap_cache_get_folio(entry, vma, vmf->address);
3748 if (folio)
3749 page = folio_file_page(folio, swp_offset(entry));
3750 swapcache = folio;
3751
3752 if (!folio) {
3753 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
3754 __swap_count(entry) == 1) {
3755 /* skip swapcache */
3756 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
3757 vma, vmf->address, false);
3758 page = &folio->page;
3759 if (folio) {
3760 __folio_set_locked(folio);
3761 __folio_set_swapbacked(folio);
3762
3763 if (mem_cgroup_swapin_charge_folio(folio,
3764 vma->vm_mm, GFP_KERNEL,
3765 entry)) {
3766 ret = VM_FAULT_OOM;
3767 goto out_page;
3768 }
3769 mem_cgroup_swapin_uncharge_swap(entry);
3770
3771 shadow = get_shadow_from_swap_cache(entry);
3772 if (shadow)
3773 workingset_refault(folio, shadow);
3774
3775 folio_add_lru(folio);
3776
3777 /* To provide entry to swap_readpage() */
3778 folio_set_swap_entry(folio, entry);
3779 swap_readpage(page, true, NULL);
3780 folio->private = NULL;
3781 }
3782 } else {
3783 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3784 vmf);
3785 if (page)
3786 folio = page_folio(page);
3787 swapcache = folio;
3788 }
3789
3790 if (!folio) {
3791 /*
3792 * Back out if somebody else faulted in this pte
3793 * while we released the pte lock.
3794 */
3795 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3796 vmf->address, &vmf->ptl);
3797 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3798 ret = VM_FAULT_OOM;
3799 goto unlock;
3800 }
3801
3802 /* Had to read the page from swap area: Major fault */
3803 ret = VM_FAULT_MAJOR;
3804 count_vm_event(PGMAJFAULT);
3805 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3806 } else if (PageHWPoison(page)) {
3807 /*
3808 * hwpoisoned dirty swapcache pages are kept for killing
3809 * owner processes (which may be unknown at hwpoison time)
3810 */
3811 ret = VM_FAULT_HWPOISON;
3812 goto out_release;
3813 }
3814
3815 locked = folio_lock_or_retry(folio, vma->vm_mm, vmf->flags);
3816
3817 if (!locked) {
3818 ret |= VM_FAULT_RETRY;
3819 goto out_release;
3820 }
3821
3822 if (swapcache) {
3823 /*
3824 * Make sure folio_free_swap() or swapoff did not release the
3825 * swapcache from under us. The page pin, and pte_same test
3826 * below, are not enough to exclude that. Even if it is still
3827 * swapcache, we need to check that the page's swap has not
3828 * changed.
3829 */
3830 if (unlikely(!folio_test_swapcache(folio) ||
3831 page_private(page) != entry.val))
3832 goto out_page;
3833
3834 /*
3835 * KSM sometimes has to copy on read faults, for example, if
3836 * page->index of !PageKSM() pages would be nonlinear inside the
3837 * anon VMA -- PageKSM() is lost on actual swapout.
3838 */
3839 page = ksm_might_need_to_copy(page, vma, vmf->address);
3840 if (unlikely(!page)) {
3841 ret = VM_FAULT_OOM;
3842 goto out_page;
3843 } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) {
3844 ret = VM_FAULT_HWPOISON;
3845 goto out_page;
3846 }
3847 folio = page_folio(page);
3848
3849 /*
3850 * If we want to map a page that's in the swapcache writable, we
3851 * have to detect via the refcount if we're really the exclusive
3852 * owner. Try removing the extra reference from the local LRU
3853 * pagevecs if required.
3854 */
3855 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
3856 !folio_test_ksm(folio) && !folio_test_lru(folio))
3857 lru_add_drain();
3858 }
3859
3860 cgroup_throttle_swaprate(page, GFP_KERNEL);
3861
3862 /*
3863 * Back out if somebody else already faulted in this pte.
3864 */
3865 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3866 &vmf->ptl);
3867 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3868 goto out_nomap;
3869
3870 if (unlikely(!folio_test_uptodate(folio))) {
3871 ret = VM_FAULT_SIGBUS;
3872 goto out_nomap;
3873 }
3874
3875 /*
3876 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
3877 * must never point at an anonymous page in the swapcache that is
3878 * PG_anon_exclusive. Sanity check that this holds and especially, that
3879 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
3880 * check after taking the PT lock and making sure that nobody
3881 * concurrently faulted in this page and set PG_anon_exclusive.
3882 */
3883 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
3884 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
3885
3886 /*
3887 * Check under PT lock (to protect against concurrent fork() sharing
3888 * the swap entry concurrently) for certainly exclusive pages.
3889 */
3890 if (!folio_test_ksm(folio)) {
3891 /*
3892 * Note that pte_swp_exclusive() == false for architectures
3893 * without __HAVE_ARCH_PTE_SWP_EXCLUSIVE.
3894 */
3895 exclusive = pte_swp_exclusive(vmf->orig_pte);
3896 if (folio != swapcache) {
3897 /*
3898 * We have a fresh page that is not exposed to the
3899 * swapcache -> certainly exclusive.
3900 */
3901 exclusive = true;
3902 } else if (exclusive && folio_test_writeback(folio) &&
3903 data_race(si->flags & SWP_STABLE_WRITES)) {
3904 /*
3905 * This is tricky: not all swap backends support
3906 * concurrent page modifications while under writeback.
3907 *
3908 * So if we stumble over such a page in the swapcache
3909 * we must not set the page exclusive, otherwise we can
3910 * map it writable without further checks and modify it
3911 * while still under writeback.
3912 *
3913 * For these problematic swap backends, simply drop the
3914 * exclusive marker: this is perfectly fine as we start
3915 * writeback only if we fully unmapped the page and
3916 * there are no unexpected references on the page after
3917 * unmapping succeeded. After fully unmapped, no
3918 * further GUP references (FOLL_GET and FOLL_PIN) can
3919 * appear, so dropping the exclusive marker and mapping
3920 * it only R/O is fine.
3921 */
3922 exclusive = false;
3923 }
3924 }
3925
3926 /*
3927 * Remove the swap entry and conditionally try to free up the swapcache.
3928 * We're already holding a reference on the page but haven't mapped it
3929 * yet.
3930 */
3931 swap_free(entry);
3932 if (should_try_to_free_swap(folio, vma, vmf->flags))
3933 folio_free_swap(folio);
3934
3935 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
3936 dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
3937 pte = mk_pte(page, vma->vm_page_prot);
3938
3939 /*
3940 * Same logic as in do_wp_page(); however, optimize for pages that are
3941 * certainly not shared either because we just allocated them without
3942 * exposing them to the swapcache or because the swap entry indicates
3943 * exclusivity.
3944 */
3945 if (!folio_test_ksm(folio) &&
3946 (exclusive || folio_ref_count(folio) == 1)) {
3947 if (vmf->flags & FAULT_FLAG_WRITE) {
3948 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3949 vmf->flags &= ~FAULT_FLAG_WRITE;
3950 }
3951 rmap_flags |= RMAP_EXCLUSIVE;
3952 }
3953 flush_icache_page(vma, page);
3954 if (pte_swp_soft_dirty(vmf->orig_pte))
3955 pte = pte_mksoft_dirty(pte);
3956 if (pte_swp_uffd_wp(vmf->orig_pte)) {
3957 pte = pte_mkuffd_wp(pte);
3958 pte = pte_wrprotect(pte);
3959 }
3960 vmf->orig_pte = pte;
3961
3962 /* ksm created a completely new copy */
3963 if (unlikely(folio != swapcache && swapcache)) {
3964 page_add_new_anon_rmap(page, vma, vmf->address);
3965 folio_add_lru_vma(folio, vma);
3966 } else {
3967 page_add_anon_rmap(page, vma, vmf->address, rmap_flags);
3968 }
3969
3970 VM_BUG_ON(!folio_test_anon(folio) ||
3971 (pte_write(pte) && !PageAnonExclusive(page)));
3972 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3973 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3974
3975 folio_unlock(folio);
3976 if (folio != swapcache && swapcache) {
3977 /*
3978 * Hold the lock to avoid the swap entry to be reused
3979 * until we take the PT lock for the pte_same() check
3980 * (to avoid false positives from pte_same). For
3981 * further safety release the lock after the swap_free
3982 * so that the swap count won't change under a
3983 * parallel locked swapcache.
3984 */
3985 folio_unlock(swapcache);
3986 folio_put(swapcache);
3987 }
3988
3989 if (vmf->flags & FAULT_FLAG_WRITE) {
3990 ret |= do_wp_page(vmf);
3991 if (ret & VM_FAULT_ERROR)
3992 ret &= VM_FAULT_ERROR;
3993 goto out;
3994 }
3995
3996 /* No need to invalidate - it was non-present before */
3997 update_mmu_cache(vma, vmf->address, vmf->pte);
3998unlock:
3999 pte_unmap_unlock(vmf->pte, vmf->ptl);
4000out:
4001 if (si)
4002 put_swap_device(si);
4003 return ret;
4004out_nomap:
4005 pte_unmap_unlock(vmf->pte, vmf->ptl);
4006out_page:
4007 folio_unlock(folio);
4008out_release:
4009 folio_put(folio);
4010 if (folio != swapcache && swapcache) {
4011 folio_unlock(swapcache);
4012 folio_put(swapcache);
4013 }
4014 if (si)
4015 put_swap_device(si);
4016 return ret;
4017}
4018
4019/*
4020 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4021 * but allow concurrent faults), and pte mapped but not yet locked.
4022 * We return with mmap_lock still held, but pte unmapped and unlocked.
4023 */
4024static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
4025{
4026 struct vm_area_struct *vma = vmf->vma;
4027 struct page *page;
4028 vm_fault_t ret = 0;
4029 pte_t entry;
4030
4031 /* File mapping without ->vm_ops ? */
4032 if (vma->vm_flags & VM_SHARED)
4033 return VM_FAULT_SIGBUS;
4034
4035 /*
4036 * Use pte_alloc() instead of pte_alloc_map(). We can't run
4037 * pte_offset_map() on pmds where a huge pmd might be created
4038 * from a different thread.
4039 *
4040 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
4041 * parallel threads are excluded by other means.
4042 *
4043 * Here we only have mmap_read_lock(mm).
4044 */
4045 if (pte_alloc(vma->vm_mm, vmf->pmd))
4046 return VM_FAULT_OOM;
4047
4048 /* See comment in handle_pte_fault() */
4049 if (unlikely(pmd_trans_unstable(vmf->pmd)))
4050 return 0;
4051
4052 /* Use the zero-page for reads */
4053 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
4054 !mm_forbids_zeropage(vma->vm_mm)) {
4055 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
4056 vma->vm_page_prot));
4057 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4058 vmf->address, &vmf->ptl);
4059 if (!pte_none(*vmf->pte)) {
4060 update_mmu_tlb(vma, vmf->address, vmf->pte);
4061 goto unlock;
4062 }
4063 ret = check_stable_address_space(vma->vm_mm);
4064 if (ret)
4065 goto unlock;
4066 /* Deliver the page fault to userland, check inside PT lock */
4067 if (userfaultfd_missing(vma)) {
4068 pte_unmap_unlock(vmf->pte, vmf->ptl);
4069 return handle_userfault(vmf, VM_UFFD_MISSING);
4070 }
4071 goto setpte;
4072 }
4073
4074 /* Allocate our own private page. */
4075 if (unlikely(anon_vma_prepare(vma)))
4076 goto oom;
4077 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
4078 if (!page)
4079 goto oom;
4080
4081 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL))
4082 goto oom_free_page;
4083 cgroup_throttle_swaprate(page, GFP_KERNEL);
4084
4085 /*
4086 * The memory barrier inside __SetPageUptodate makes sure that
4087 * preceding stores to the page contents become visible before
4088 * the set_pte_at() write.
4089 */
4090 __SetPageUptodate(page);
4091
4092 entry = mk_pte(page, vma->vm_page_prot);
4093 entry = pte_sw_mkyoung(entry);
4094 if (vma->vm_flags & VM_WRITE)
4095 entry = pte_mkwrite(pte_mkdirty(entry));
4096
4097 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
4098 &vmf->ptl);
4099 if (!pte_none(*vmf->pte)) {
4100 update_mmu_tlb(vma, vmf->address, vmf->pte);
4101 goto release;
4102 }
4103
4104 ret = check_stable_address_space(vma->vm_mm);
4105 if (ret)
4106 goto release;
4107
4108 /* Deliver the page fault to userland, check inside PT lock */
4109 if (userfaultfd_missing(vma)) {
4110 pte_unmap_unlock(vmf->pte, vmf->ptl);
4111 put_page(page);
4112 return handle_userfault(vmf, VM_UFFD_MISSING);
4113 }
4114
4115 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
4116 page_add_new_anon_rmap(page, vma, vmf->address);
4117 lru_cache_add_inactive_or_unevictable(page, vma);
4118setpte:
4119 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
4120
4121 /* No need to invalidate - it was non-present before */
4122 update_mmu_cache(vma, vmf->address, vmf->pte);
4123unlock:
4124 pte_unmap_unlock(vmf->pte, vmf->ptl);
4125 return ret;
4126release:
4127 put_page(page);
4128 goto unlock;
4129oom_free_page:
4130 put_page(page);
4131oom:
4132 return VM_FAULT_OOM;
4133}
4134
4135/*
4136 * The mmap_lock must have been held on entry, and may have been
4137 * released depending on flags and vma->vm_ops->fault() return value.
4138 * See filemap_fault() and __lock_page_retry().
4139 */
4140static vm_fault_t __do_fault(struct vm_fault *vmf)
4141{
4142 struct vm_area_struct *vma = vmf->vma;
4143 vm_fault_t ret;
4144
4145 /*
4146 * Preallocate pte before we take page_lock because this might lead to
4147 * deadlocks for memcg reclaim which waits for pages under writeback:
4148 * lock_page(A)
4149 * SetPageWriteback(A)
4150 * unlock_page(A)
4151 * lock_page(B)
4152 * lock_page(B)
4153 * pte_alloc_one
4154 * shrink_page_list
4155 * wait_on_page_writeback(A)
4156 * SetPageWriteback(B)
4157 * unlock_page(B)
4158 * # flush A, B to clear the writeback
4159 */
4160 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
4161 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4162 if (!vmf->prealloc_pte)
4163 return VM_FAULT_OOM;
4164 }
4165
4166 ret = vma->vm_ops->fault(vmf);
4167 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
4168 VM_FAULT_DONE_COW)))
4169 return ret;
4170
4171 if (unlikely(PageHWPoison(vmf->page))) {
4172 struct page *page = vmf->page;
4173 vm_fault_t poisonret = VM_FAULT_HWPOISON;
4174 if (ret & VM_FAULT_LOCKED) {
4175 if (page_mapped(page))
4176 unmap_mapping_pages(page_mapping(page),
4177 page->index, 1, false);
4178 /* Retry if a clean page was removed from the cache. */
4179 if (invalidate_inode_page(page))
4180 poisonret = VM_FAULT_NOPAGE;
4181 unlock_page(page);
4182 }
4183 put_page(page);
4184 vmf->page = NULL;
4185 return poisonret;
4186 }
4187
4188 if (unlikely(!(ret & VM_FAULT_LOCKED)))
4189 lock_page(vmf->page);
4190 else
4191 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
4192
4193 return ret;
4194}
4195
4196#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4197static void deposit_prealloc_pte(struct vm_fault *vmf)
4198{
4199 struct vm_area_struct *vma = vmf->vma;
4200
4201 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
4202 /*
4203 * We are going to consume the prealloc table,
4204 * count that as nr_ptes.
4205 */
4206 mm_inc_nr_ptes(vma->vm_mm);
4207 vmf->prealloc_pte = NULL;
4208}
4209
4210vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4211{
4212 struct vm_area_struct *vma = vmf->vma;
4213 bool write = vmf->flags & FAULT_FLAG_WRITE;
4214 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
4215 pmd_t entry;
4216 int i;
4217 vm_fault_t ret = VM_FAULT_FALLBACK;
4218
4219 if (!transhuge_vma_suitable(vma, haddr))
4220 return ret;
4221
4222 page = compound_head(page);
4223 if (compound_order(page) != HPAGE_PMD_ORDER)
4224 return ret;
4225
4226 /*
4227 * Just backoff if any subpage of a THP is corrupted otherwise
4228 * the corrupted page may mapped by PMD silently to escape the
4229 * check. This kind of THP just can be PTE mapped. Access to
4230 * the corrupted subpage should trigger SIGBUS as expected.
4231 */
4232 if (unlikely(PageHasHWPoisoned(page)))
4233 return ret;
4234
4235 /*
4236 * Archs like ppc64 need additional space to store information
4237 * related to pte entry. Use the preallocated table for that.
4238 */
4239 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
4240 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4241 if (!vmf->prealloc_pte)
4242 return VM_FAULT_OOM;
4243 }
4244
4245 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4246 if (unlikely(!pmd_none(*vmf->pmd)))
4247 goto out;
4248
4249 for (i = 0; i < HPAGE_PMD_NR; i++)
4250 flush_icache_page(vma, page + i);
4251
4252 entry = mk_huge_pmd(page, vma->vm_page_prot);
4253 if (write)
4254 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
4255
4256 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
4257 page_add_file_rmap(page, vma, true);
4258
4259 /*
4260 * deposit and withdraw with pmd lock held
4261 */
4262 if (arch_needs_pgtable_deposit())
4263 deposit_prealloc_pte(vmf);
4264
4265 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
4266
4267 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
4268
4269 /* fault is handled */
4270 ret = 0;
4271 count_vm_event(THP_FILE_MAPPED);
4272out:
4273 spin_unlock(vmf->ptl);
4274 return ret;
4275}
4276#else
4277vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4278{
4279 return VM_FAULT_FALLBACK;
4280}
4281#endif
4282
4283void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
4284{
4285 struct vm_area_struct *vma = vmf->vma;
4286 bool uffd_wp = pte_marker_uffd_wp(vmf->orig_pte);
4287 bool write = vmf->flags & FAULT_FLAG_WRITE;
4288 bool prefault = vmf->address != addr;
4289 pte_t entry;
4290
4291 flush_icache_page(vma, page);
4292 entry = mk_pte(page, vma->vm_page_prot);
4293
4294 if (prefault && arch_wants_old_prefaulted_pte())
4295 entry = pte_mkold(entry);
4296 else
4297 entry = pte_sw_mkyoung(entry);
4298
4299 if (write)
4300 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
4301 if (unlikely(uffd_wp))
4302 entry = pte_mkuffd_wp(pte_wrprotect(entry));
4303 /* copy-on-write page */
4304 if (write && !(vma->vm_flags & VM_SHARED)) {
4305 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
4306 page_add_new_anon_rmap(page, vma, addr);
4307 lru_cache_add_inactive_or_unevictable(page, vma);
4308 } else {
4309 inc_mm_counter(vma->vm_mm, mm_counter_file(page));
4310 page_add_file_rmap(page, vma, false);
4311 }
4312 set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
4313}
4314
4315static bool vmf_pte_changed(struct vm_fault *vmf)
4316{
4317 if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)
4318 return !pte_same(*vmf->pte, vmf->orig_pte);
4319
4320 return !pte_none(*vmf->pte);
4321}
4322
4323/**
4324 * finish_fault - finish page fault once we have prepared the page to fault
4325 *
4326 * @vmf: structure describing the fault
4327 *
4328 * This function handles all that is needed to finish a page fault once the
4329 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
4330 * given page, adds reverse page mapping, handles memcg charges and LRU
4331 * addition.
4332 *
4333 * The function expects the page to be locked and on success it consumes a
4334 * reference of a page being mapped (for the PTE which maps it).
4335 *
4336 * Return: %0 on success, %VM_FAULT_ code in case of error.
4337 */
4338vm_fault_t finish_fault(struct vm_fault *vmf)
4339{
4340 struct vm_area_struct *vma = vmf->vma;
4341 struct page *page;
4342 vm_fault_t ret;
4343
4344 /* Did we COW the page? */
4345 if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
4346 page = vmf->cow_page;
4347 else
4348 page = vmf->page;
4349
4350 /*
4351 * check even for read faults because we might have lost our CoWed
4352 * page
4353 */
4354 if (!(vma->vm_flags & VM_SHARED)) {
4355 ret = check_stable_address_space(vma->vm_mm);
4356 if (ret)
4357 return ret;
4358 }
4359
4360 if (pmd_none(*vmf->pmd)) {
4361 if (PageTransCompound(page)) {
4362 ret = do_set_pmd(vmf, page);
4363 if (ret != VM_FAULT_FALLBACK)
4364 return ret;
4365 }
4366
4367 if (vmf->prealloc_pte)
4368 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
4369 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
4370 return VM_FAULT_OOM;
4371 }
4372
4373 /*
4374 * See comment in handle_pte_fault() for how this scenario happens, we
4375 * need to return NOPAGE so that we drop this page.
4376 */
4377 if (pmd_devmap_trans_unstable(vmf->pmd))
4378 return VM_FAULT_NOPAGE;
4379
4380 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4381 vmf->address, &vmf->ptl);
4382
4383 /* Re-check under ptl */
4384 if (likely(!vmf_pte_changed(vmf))) {
4385 do_set_pte(vmf, page, vmf->address);
4386
4387 /* no need to invalidate: a not-present page won't be cached */
4388 update_mmu_cache(vma, vmf->address, vmf->pte);
4389
4390 ret = 0;
4391 } else {
4392 update_mmu_tlb(vma, vmf->address, vmf->pte);
4393 ret = VM_FAULT_NOPAGE;
4394 }
4395
4396 pte_unmap_unlock(vmf->pte, vmf->ptl);
4397 return ret;
4398}
4399
4400static unsigned long fault_around_bytes __read_mostly =
4401 rounddown_pow_of_two(65536);
4402
4403#ifdef CONFIG_DEBUG_FS
4404static int fault_around_bytes_get(void *data, u64 *val)
4405{
4406 *val = fault_around_bytes;
4407 return 0;
4408}
4409
4410/*
4411 * fault_around_bytes must be rounded down to the nearest page order as it's
4412 * what do_fault_around() expects to see.
4413 */
4414static int fault_around_bytes_set(void *data, u64 val)
4415{
4416 if (val / PAGE_SIZE > PTRS_PER_PTE)
4417 return -EINVAL;
4418 if (val > PAGE_SIZE)
4419 fault_around_bytes = rounddown_pow_of_two(val);
4420 else
4421 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
4422 return 0;
4423}
4424DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
4425 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
4426
4427static int __init fault_around_debugfs(void)
4428{
4429 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
4430 &fault_around_bytes_fops);
4431 return 0;
4432}
4433late_initcall(fault_around_debugfs);
4434#endif
4435
4436/*
4437 * do_fault_around() tries to map few pages around the fault address. The hope
4438 * is that the pages will be needed soon and this will lower the number of
4439 * faults to handle.
4440 *
4441 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
4442 * not ready to be mapped: not up-to-date, locked, etc.
4443 *
4444 * This function doesn't cross the VMA boundaries, in order to call map_pages()
4445 * only once.
4446 *
4447 * fault_around_bytes defines how many bytes we'll try to map.
4448 * do_fault_around() expects it to be set to a power of two less than or equal
4449 * to PTRS_PER_PTE.
4450 *
4451 * The virtual address of the area that we map is naturally aligned to
4452 * fault_around_bytes rounded down to the machine page size
4453 * (and therefore to page order). This way it's easier to guarantee
4454 * that we don't cross page table boundaries.
4455 */
4456static vm_fault_t do_fault_around(struct vm_fault *vmf)
4457{
4458 unsigned long address = vmf->address, nr_pages, mask;
4459 pgoff_t start_pgoff = vmf->pgoff;
4460 pgoff_t end_pgoff;
4461 int off;
4462
4463 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
4464 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
4465
4466 address = max(address & mask, vmf->vma->vm_start);
4467 off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
4468 start_pgoff -= off;
4469
4470 /*
4471 * end_pgoff is either the end of the page table, the end of
4472 * the vma or nr_pages from start_pgoff, depending what is nearest.
4473 */
4474 end_pgoff = start_pgoff -
4475 ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
4476 PTRS_PER_PTE - 1;
4477 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
4478 start_pgoff + nr_pages - 1);
4479
4480 if (pmd_none(*vmf->pmd)) {
4481 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
4482 if (!vmf->prealloc_pte)
4483 return VM_FAULT_OOM;
4484 }
4485
4486 return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
4487}
4488
4489/* Return true if we should do read fault-around, false otherwise */
4490static inline bool should_fault_around(struct vm_fault *vmf)
4491{
4492 /* No ->map_pages? No way to fault around... */
4493 if (!vmf->vma->vm_ops->map_pages)
4494 return false;
4495
4496 if (uffd_disable_fault_around(vmf->vma))
4497 return false;
4498
4499 return fault_around_bytes >> PAGE_SHIFT > 1;
4500}
4501
4502static vm_fault_t do_read_fault(struct vm_fault *vmf)
4503{
4504 vm_fault_t ret = 0;
4505
4506 /*
4507 * Let's call ->map_pages() first and use ->fault() as fallback
4508 * if page by the offset is not ready to be mapped (cold cache or
4509 * something).
4510 */
4511 if (should_fault_around(vmf)) {
4512 ret = do_fault_around(vmf);
4513 if (ret)
4514 return ret;
4515 }
4516
4517 ret = __do_fault(vmf);
4518 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4519 return ret;
4520
4521 ret |= finish_fault(vmf);
4522 unlock_page(vmf->page);
4523 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4524 put_page(vmf->page);
4525 return ret;
4526}
4527
4528static vm_fault_t do_cow_fault(struct vm_fault *vmf)
4529{
4530 struct vm_area_struct *vma = vmf->vma;
4531 vm_fault_t ret;
4532
4533 if (unlikely(anon_vma_prepare(vma)))
4534 return VM_FAULT_OOM;
4535
4536 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
4537 if (!vmf->cow_page)
4538 return VM_FAULT_OOM;
4539
4540 if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm,
4541 GFP_KERNEL)) {
4542 put_page(vmf->cow_page);
4543 return VM_FAULT_OOM;
4544 }
4545 cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL);
4546
4547 ret = __do_fault(vmf);
4548 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4549 goto uncharge_out;
4550 if (ret & VM_FAULT_DONE_COW)
4551 return ret;
4552
4553 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
4554 __SetPageUptodate(vmf->cow_page);
4555
4556 ret |= finish_fault(vmf);
4557 unlock_page(vmf->page);
4558 put_page(vmf->page);
4559 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4560 goto uncharge_out;
4561 return ret;
4562uncharge_out:
4563 put_page(vmf->cow_page);
4564 return ret;
4565}
4566
4567static vm_fault_t do_shared_fault(struct vm_fault *vmf)
4568{
4569 struct vm_area_struct *vma = vmf->vma;
4570 vm_fault_t ret, tmp;
4571
4572 ret = __do_fault(vmf);
4573 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4574 return ret;
4575
4576 /*
4577 * Check if the backing address space wants to know that the page is
4578 * about to become writable
4579 */
4580 if (vma->vm_ops->page_mkwrite) {
4581 unlock_page(vmf->page);
4582 tmp = do_page_mkwrite(vmf);
4583 if (unlikely(!tmp ||
4584 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
4585 put_page(vmf->page);
4586 return tmp;
4587 }
4588 }
4589
4590 ret |= finish_fault(vmf);
4591 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
4592 VM_FAULT_RETRY))) {
4593 unlock_page(vmf->page);
4594 put_page(vmf->page);
4595 return ret;
4596 }
4597
4598 ret |= fault_dirty_shared_page(vmf);
4599 return ret;
4600}
4601
4602/*
4603 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4604 * but allow concurrent faults).
4605 * The mmap_lock may have been released depending on flags and our
4606 * return value. See filemap_fault() and __folio_lock_or_retry().
4607 * If mmap_lock is released, vma may become invalid (for example
4608 * by other thread calling munmap()).
4609 */
4610static vm_fault_t do_fault(struct vm_fault *vmf)
4611{
4612 struct vm_area_struct *vma = vmf->vma;
4613 struct mm_struct *vm_mm = vma->vm_mm;
4614 vm_fault_t ret;
4615
4616 /*
4617 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4618 */
4619 if (!vma->vm_ops->fault) {
4620 /*
4621 * If we find a migration pmd entry or a none pmd entry, which
4622 * should never happen, return SIGBUS
4623 */
4624 if (unlikely(!pmd_present(*vmf->pmd)))
4625 ret = VM_FAULT_SIGBUS;
4626 else {
4627 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
4628 vmf->pmd,
4629 vmf->address,
4630 &vmf->ptl);
4631 /*
4632 * Make sure this is not a temporary clearing of pte
4633 * by holding ptl and checking again. A R/M/W update
4634 * of pte involves: take ptl, clearing the pte so that
4635 * we don't have concurrent modification by hardware
4636 * followed by an update.
4637 */
4638 if (unlikely(pte_none(*vmf->pte)))
4639 ret = VM_FAULT_SIGBUS;
4640 else
4641 ret = VM_FAULT_NOPAGE;
4642
4643 pte_unmap_unlock(vmf->pte, vmf->ptl);
4644 }
4645 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
4646 ret = do_read_fault(vmf);
4647 else if (!(vma->vm_flags & VM_SHARED))
4648 ret = do_cow_fault(vmf);
4649 else
4650 ret = do_shared_fault(vmf);
4651
4652 /* preallocated pagetable is unused: free it */
4653 if (vmf->prealloc_pte) {
4654 pte_free(vm_mm, vmf->prealloc_pte);
4655 vmf->prealloc_pte = NULL;
4656 }
4657 return ret;
4658}
4659
4660int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
4661 unsigned long addr, int page_nid, int *flags)
4662{
4663 get_page(page);
4664
4665 count_vm_numa_event(NUMA_HINT_FAULTS);
4666 if (page_nid == numa_node_id()) {
4667 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
4668 *flags |= TNF_FAULT_LOCAL;
4669 }
4670
4671 return mpol_misplaced(page, vma, addr);
4672}
4673
4674static vm_fault_t do_numa_page(struct vm_fault *vmf)
4675{
4676 struct vm_area_struct *vma = vmf->vma;
4677 struct page *page = NULL;
4678 int page_nid = NUMA_NO_NODE;
4679 bool writable = false;
4680 int last_cpupid;
4681 int target_nid;
4682 pte_t pte, old_pte;
4683 int flags = 0;
4684
4685 /*
4686 * The "pte" at this point cannot be used safely without
4687 * validation through pte_unmap_same(). It's of NUMA type but
4688 * the pfn may be screwed if the read is non atomic.
4689 */
4690 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
4691 spin_lock(vmf->ptl);
4692 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4693 pte_unmap_unlock(vmf->pte, vmf->ptl);
4694 goto out;
4695 }
4696
4697 /* Get the normal PTE */
4698 old_pte = ptep_get(vmf->pte);
4699 pte = pte_modify(old_pte, vma->vm_page_prot);
4700
4701 /*
4702 * Detect now whether the PTE could be writable; this information
4703 * is only valid while holding the PT lock.
4704 */
4705 writable = pte_write(pte);
4706 if (!writable && vma_wants_manual_pte_write_upgrade(vma) &&
4707 can_change_pte_writable(vma, vmf->address, pte))
4708 writable = true;
4709
4710 page = vm_normal_page(vma, vmf->address, pte);
4711 if (!page || is_zone_device_page(page))
4712 goto out_map;
4713
4714 /* TODO: handle PTE-mapped THP */
4715 if (PageCompound(page))
4716 goto out_map;
4717
4718 /*
4719 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4720 * much anyway since they can be in shared cache state. This misses
4721 * the case where a mapping is writable but the process never writes
4722 * to it but pte_write gets cleared during protection updates and
4723 * pte_dirty has unpredictable behaviour between PTE scan updates,
4724 * background writeback, dirty balancing and application behaviour.
4725 */
4726 if (!writable)
4727 flags |= TNF_NO_GROUP;
4728
4729 /*
4730 * Flag if the page is shared between multiple address spaces. This
4731 * is later used when determining whether to group tasks together
4732 */
4733 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
4734 flags |= TNF_SHARED;
4735
4736 page_nid = page_to_nid(page);
4737 /*
4738 * For memory tiering mode, cpupid of slow memory page is used
4739 * to record page access time. So use default value.
4740 */
4741 if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
4742 !node_is_toptier(page_nid))
4743 last_cpupid = (-1 & LAST_CPUPID_MASK);
4744 else
4745 last_cpupid = page_cpupid_last(page);
4746 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
4747 &flags);
4748 if (target_nid == NUMA_NO_NODE) {
4749 put_page(page);
4750 goto out_map;
4751 }
4752 pte_unmap_unlock(vmf->pte, vmf->ptl);
4753 writable = false;
4754
4755 /* Migrate to the requested node */
4756 if (migrate_misplaced_page(page, vma, target_nid)) {
4757 page_nid = target_nid;
4758 flags |= TNF_MIGRATED;
4759 } else {
4760 flags |= TNF_MIGRATE_FAIL;
4761 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4762 spin_lock(vmf->ptl);
4763 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4764 pte_unmap_unlock(vmf->pte, vmf->ptl);
4765 goto out;
4766 }
4767 goto out_map;
4768 }
4769
4770out:
4771 if (page_nid != NUMA_NO_NODE)
4772 task_numa_fault(last_cpupid, page_nid, 1, flags);
4773 return 0;
4774out_map:
4775 /*
4776 * Make it present again, depending on how arch implements
4777 * non-accessible ptes, some can allow access by kernel mode.
4778 */
4779 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
4780 pte = pte_modify(old_pte, vma->vm_page_prot);
4781 pte = pte_mkyoung(pte);
4782 if (writable)
4783 pte = pte_mkwrite(pte);
4784 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
4785 update_mmu_cache(vma, vmf->address, vmf->pte);
4786 pte_unmap_unlock(vmf->pte, vmf->ptl);
4787 goto out;
4788}
4789
4790static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
4791{
4792 if (vma_is_anonymous(vmf->vma))
4793 return do_huge_pmd_anonymous_page(vmf);
4794 if (vmf->vma->vm_ops->huge_fault)
4795 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4796 return VM_FAULT_FALLBACK;
4797}
4798
4799/* `inline' is required to avoid gcc 4.1.2 build error */
4800static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
4801{
4802 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
4803 vm_fault_t ret;
4804
4805 if (vma_is_anonymous(vmf->vma)) {
4806 if (likely(!unshare) &&
4807 userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd))
4808 return handle_userfault(vmf, VM_UFFD_WP);
4809 return do_huge_pmd_wp_page(vmf);
4810 }
4811
4812 if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
4813 if (vmf->vma->vm_ops->huge_fault) {
4814 ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4815 if (!(ret & VM_FAULT_FALLBACK))
4816 return ret;
4817 }
4818 }
4819
4820 /* COW or write-notify handled on pte level: split pmd. */
4821 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
4822
4823 return VM_FAULT_FALLBACK;
4824}
4825
4826static vm_fault_t create_huge_pud(struct vm_fault *vmf)
4827{
4828#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4829 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4830 /* No support for anonymous transparent PUD pages yet */
4831 if (vma_is_anonymous(vmf->vma))
4832 return VM_FAULT_FALLBACK;
4833 if (vmf->vma->vm_ops->huge_fault)
4834 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4835#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4836 return VM_FAULT_FALLBACK;
4837}
4838
4839static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
4840{
4841#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4842 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4843 vm_fault_t ret;
4844
4845 /* No support for anonymous transparent PUD pages yet */
4846 if (vma_is_anonymous(vmf->vma))
4847 goto split;
4848 if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
4849 if (vmf->vma->vm_ops->huge_fault) {
4850 ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4851 if (!(ret & VM_FAULT_FALLBACK))
4852 return ret;
4853 }
4854 }
4855split:
4856 /* COW or write-notify not handled on PUD level: split pud.*/
4857 __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
4858#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
4859 return VM_FAULT_FALLBACK;
4860}
4861
4862/*
4863 * These routines also need to handle stuff like marking pages dirty
4864 * and/or accessed for architectures that don't do it in hardware (most
4865 * RISC architectures). The early dirtying is also good on the i386.
4866 *
4867 * There is also a hook called "update_mmu_cache()" that architectures
4868 * with external mmu caches can use to update those (ie the Sparc or
4869 * PowerPC hashed page tables that act as extended TLBs).
4870 *
4871 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
4872 * concurrent faults).
4873 *
4874 * The mmap_lock may have been released depending on flags and our return value.
4875 * See filemap_fault() and __folio_lock_or_retry().
4876 */
4877static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
4878{
4879 pte_t entry;
4880
4881 if (unlikely(pmd_none(*vmf->pmd))) {
4882 /*
4883 * Leave __pte_alloc() until later: because vm_ops->fault may
4884 * want to allocate huge page, and if we expose page table
4885 * for an instant, it will be difficult to retract from
4886 * concurrent faults and from rmap lookups.
4887 */
4888 vmf->pte = NULL;
4889 vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID;
4890 } else {
4891 /*
4892 * If a huge pmd materialized under us just retry later. Use
4893 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead
4894 * of pmd_trans_huge() to ensure the pmd didn't become
4895 * pmd_trans_huge under us and then back to pmd_none, as a
4896 * result of MADV_DONTNEED running immediately after a huge pmd
4897 * fault in a different thread of this mm, in turn leading to a
4898 * misleading pmd_trans_huge() retval. All we have to ensure is
4899 * that it is a regular pmd that we can walk with
4900 * pte_offset_map() and we can do that through an atomic read
4901 * in C, which is what pmd_trans_unstable() provides.
4902 */
4903 if (pmd_devmap_trans_unstable(vmf->pmd))
4904 return 0;
4905 /*
4906 * A regular pmd is established and it can't morph into a huge
4907 * pmd from under us anymore at this point because we hold the
4908 * mmap_lock read mode and khugepaged takes it in write mode.
4909 * So now it's safe to run pte_offset_map().
4910 */
4911 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4912 vmf->orig_pte = *vmf->pte;
4913 vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID;
4914
4915 /*
4916 * some architectures can have larger ptes than wordsize,
4917 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4918 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4919 * accesses. The code below just needs a consistent view
4920 * for the ifs and we later double check anyway with the
4921 * ptl lock held. So here a barrier will do.
4922 */
4923 barrier();
4924 if (pte_none(vmf->orig_pte)) {
4925 pte_unmap(vmf->pte);
4926 vmf->pte = NULL;
4927 }
4928 }
4929
4930 if (!vmf->pte) {
4931 if (vma_is_anonymous(vmf->vma))
4932 return do_anonymous_page(vmf);
4933 else
4934 return do_fault(vmf);
4935 }
4936
4937 if (!pte_present(vmf->orig_pte))
4938 return do_swap_page(vmf);
4939
4940 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
4941 return do_numa_page(vmf);
4942
4943 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
4944 spin_lock(vmf->ptl);
4945 entry = vmf->orig_pte;
4946 if (unlikely(!pte_same(*vmf->pte, entry))) {
4947 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
4948 goto unlock;
4949 }
4950 if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
4951 if (!pte_write(entry))
4952 return do_wp_page(vmf);
4953 else if (likely(vmf->flags & FAULT_FLAG_WRITE))
4954 entry = pte_mkdirty(entry);
4955 }
4956 entry = pte_mkyoung(entry);
4957 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
4958 vmf->flags & FAULT_FLAG_WRITE)) {
4959 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
4960 } else {
4961 /* Skip spurious TLB flush for retried page fault */
4962 if (vmf->flags & FAULT_FLAG_TRIED)
4963 goto unlock;
4964 /*
4965 * This is needed only for protection faults but the arch code
4966 * is not yet telling us if this is a protection fault or not.
4967 * This still avoids useless tlb flushes for .text page faults
4968 * with threads.
4969 */
4970 if (vmf->flags & FAULT_FLAG_WRITE)
4971 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
4972 }
4973unlock:
4974 pte_unmap_unlock(vmf->pte, vmf->ptl);
4975 return 0;
4976}
4977
4978/*
4979 * By the time we get here, we already hold the mm semaphore
4980 *
4981 * The mmap_lock may have been released depending on flags and our
4982 * return value. See filemap_fault() and __folio_lock_or_retry().
4983 */
4984static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
4985 unsigned long address, unsigned int flags)
4986{
4987 struct vm_fault vmf = {
4988 .vma = vma,
4989 .address = address & PAGE_MASK,
4990 .real_address = address,
4991 .flags = flags,
4992 .pgoff = linear_page_index(vma, address),
4993 .gfp_mask = __get_fault_gfp_mask(vma),
4994 };
4995 struct mm_struct *mm = vma->vm_mm;
4996 unsigned long vm_flags = vma->vm_flags;
4997 pgd_t *pgd;
4998 p4d_t *p4d;
4999 vm_fault_t ret;
5000
5001 pgd = pgd_offset(mm, address);
5002 p4d = p4d_alloc(mm, pgd, address);
5003 if (!p4d)
5004 return VM_FAULT_OOM;
5005
5006 vmf.pud = pud_alloc(mm, p4d, address);
5007 if (!vmf.pud)
5008 return VM_FAULT_OOM;
5009retry_pud:
5010 if (pud_none(*vmf.pud) &&
5011 hugepage_vma_check(vma, vm_flags, false, true, true)) {
5012 ret = create_huge_pud(&vmf);
5013 if (!(ret & VM_FAULT_FALLBACK))
5014 return ret;
5015 } else {
5016 pud_t orig_pud = *vmf.pud;
5017
5018 barrier();
5019 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
5020
5021 /*
5022 * TODO once we support anonymous PUDs: NUMA case and
5023 * FAULT_FLAG_UNSHARE handling.
5024 */
5025 if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) {
5026 ret = wp_huge_pud(&vmf, orig_pud);
5027 if (!(ret & VM_FAULT_FALLBACK))
5028 return ret;
5029 } else {
5030 huge_pud_set_accessed(&vmf, orig_pud);
5031 return 0;
5032 }
5033 }
5034 }
5035
5036 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
5037 if (!vmf.pmd)
5038 return VM_FAULT_OOM;
5039
5040 /* Huge pud page fault raced with pmd_alloc? */
5041 if (pud_trans_unstable(vmf.pud))
5042 goto retry_pud;
5043
5044 if (pmd_none(*vmf.pmd) &&
5045 hugepage_vma_check(vma, vm_flags, false, true, true)) {
5046 ret = create_huge_pmd(&vmf);
5047 if (!(ret & VM_FAULT_FALLBACK))
5048 return ret;
5049 } else {
5050 vmf.orig_pmd = *vmf.pmd;
5051
5052 barrier();
5053 if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
5054 VM_BUG_ON(thp_migration_supported() &&
5055 !is_pmd_migration_entry(vmf.orig_pmd));
5056 if (is_pmd_migration_entry(vmf.orig_pmd))
5057 pmd_migration_entry_wait(mm, vmf.pmd);
5058 return 0;
5059 }
5060 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
5061 if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
5062 return do_huge_pmd_numa_page(&vmf);
5063
5064 if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
5065 !pmd_write(vmf.orig_pmd)) {
5066 ret = wp_huge_pmd(&vmf);
5067 if (!(ret & VM_FAULT_FALLBACK))
5068 return ret;
5069 } else {
5070 huge_pmd_set_accessed(&vmf);
5071 return 0;
5072 }
5073 }
5074 }
5075
5076 return handle_pte_fault(&vmf);
5077}
5078
5079/**
5080 * mm_account_fault - Do page fault accounting
5081 *
5082 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
5083 * of perf event counters, but we'll still do the per-task accounting to
5084 * the task who triggered this page fault.
5085 * @address: the faulted address.
5086 * @flags: the fault flags.
5087 * @ret: the fault retcode.
5088 *
5089 * This will take care of most of the page fault accounting. Meanwhile, it
5090 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
5091 * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
5092 * still be in per-arch page fault handlers at the entry of page fault.
5093 */
5094static inline void mm_account_fault(struct pt_regs *regs,
5095 unsigned long address, unsigned int flags,
5096 vm_fault_t ret)
5097{
5098 bool major;
5099
5100 /*
5101 * We don't do accounting for some specific faults:
5102 *
5103 * - Unsuccessful faults (e.g. when the address wasn't valid). That
5104 * includes arch_vma_access_permitted() failing before reaching here.
5105 * So this is not a "this many hardware page faults" counter. We
5106 * should use the hw profiling for that.
5107 *
5108 * - Incomplete faults (VM_FAULT_RETRY). They will only be counted
5109 * once they're completed.
5110 */
5111 if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
5112 return;
5113
5114 /*
5115 * We define the fault as a major fault when the final successful fault
5116 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
5117 * handle it immediately previously).
5118 */
5119 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
5120
5121 if (major)
5122 current->maj_flt++;
5123 else
5124 current->min_flt++;
5125
5126 /*
5127 * If the fault is done for GUP, regs will be NULL. We only do the
5128 * accounting for the per thread fault counters who triggered the
5129 * fault, and we skip the perf event updates.
5130 */
5131 if (!regs)
5132 return;
5133
5134 if (major)
5135 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
5136 else
5137 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
5138}
5139
5140#ifdef CONFIG_LRU_GEN
5141static void lru_gen_enter_fault(struct vm_area_struct *vma)
5142{
5143 /* the LRU algorithm doesn't apply to sequential or random reads */
5144 current->in_lru_fault = !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ));
5145}
5146
5147static void lru_gen_exit_fault(void)
5148{
5149 current->in_lru_fault = false;
5150}
5151#else
5152static void lru_gen_enter_fault(struct vm_area_struct *vma)
5153{
5154}
5155
5156static void lru_gen_exit_fault(void)
5157{
5158}
5159#endif /* CONFIG_LRU_GEN */
5160
5161static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma,
5162 unsigned int *flags)
5163{
5164 if (unlikely(*flags & FAULT_FLAG_UNSHARE)) {
5165 if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE))
5166 return VM_FAULT_SIGSEGV;
5167 /*
5168 * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's
5169 * just treat it like an ordinary read-fault otherwise.
5170 */
5171 if (!is_cow_mapping(vma->vm_flags))
5172 *flags &= ~FAULT_FLAG_UNSHARE;
5173 } else if (*flags & FAULT_FLAG_WRITE) {
5174 /* Write faults on read-only mappings are impossible ... */
5175 if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE)))
5176 return VM_FAULT_SIGSEGV;
5177 /* ... and FOLL_FORCE only applies to COW mappings. */
5178 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) &&
5179 !is_cow_mapping(vma->vm_flags)))
5180 return VM_FAULT_SIGSEGV;
5181 }
5182 return 0;
5183}
5184
5185/*
5186 * By the time we get here, we already hold the mm semaphore
5187 *
5188 * The mmap_lock may have been released depending on flags and our
5189 * return value. See filemap_fault() and __folio_lock_or_retry().
5190 */
5191vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
5192 unsigned int flags, struct pt_regs *regs)
5193{
5194 vm_fault_t ret;
5195
5196 __set_current_state(TASK_RUNNING);
5197
5198 count_vm_event(PGFAULT);
5199 count_memcg_event_mm(vma->vm_mm, PGFAULT);
5200
5201 ret = sanitize_fault_flags(vma, &flags);
5202 if (ret)
5203 return ret;
5204
5205 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
5206 flags & FAULT_FLAG_INSTRUCTION,
5207 flags & FAULT_FLAG_REMOTE))
5208 return VM_FAULT_SIGSEGV;
5209
5210 /*
5211 * Enable the memcg OOM handling for faults triggered in user
5212 * space. Kernel faults are handled more gracefully.
5213 */
5214 if (flags & FAULT_FLAG_USER)
5215 mem_cgroup_enter_user_fault();
5216
5217 lru_gen_enter_fault(vma);
5218
5219 if (unlikely(is_vm_hugetlb_page(vma)))
5220 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
5221 else
5222 ret = __handle_mm_fault(vma, address, flags);
5223
5224 lru_gen_exit_fault();
5225
5226 if (flags & FAULT_FLAG_USER) {
5227 mem_cgroup_exit_user_fault();
5228 /*
5229 * The task may have entered a memcg OOM situation but
5230 * if the allocation error was handled gracefully (no
5231 * VM_FAULT_OOM), there is no need to kill anything.
5232 * Just clean up the OOM state peacefully.
5233 */
5234 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
5235 mem_cgroup_oom_synchronize(false);
5236 }
5237
5238 mm_account_fault(regs, address, flags, ret);
5239
5240 return ret;
5241}
5242EXPORT_SYMBOL_GPL(handle_mm_fault);
5243
5244#ifndef __PAGETABLE_P4D_FOLDED
5245/*
5246 * Allocate p4d page table.
5247 * We've already handled the fast-path in-line.
5248 */
5249int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
5250{
5251 p4d_t *new = p4d_alloc_one(mm, address);
5252 if (!new)
5253 return -ENOMEM;
5254
5255 spin_lock(&mm->page_table_lock);
5256 if (pgd_present(*pgd)) { /* Another has populated it */
5257 p4d_free(mm, new);
5258 } else {
5259 smp_wmb(); /* See comment in pmd_install() */
5260 pgd_populate(mm, pgd, new);
5261 }
5262 spin_unlock(&mm->page_table_lock);
5263 return 0;
5264}
5265#endif /* __PAGETABLE_P4D_FOLDED */
5266
5267#ifndef __PAGETABLE_PUD_FOLDED
5268/*
5269 * Allocate page upper directory.
5270 * We've already handled the fast-path in-line.
5271 */
5272int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
5273{
5274 pud_t *new = pud_alloc_one(mm, address);
5275 if (!new)
5276 return -ENOMEM;
5277
5278 spin_lock(&mm->page_table_lock);
5279 if (!p4d_present(*p4d)) {
5280 mm_inc_nr_puds(mm);
5281 smp_wmb(); /* See comment in pmd_install() */
5282 p4d_populate(mm, p4d, new);
5283 } else /* Another has populated it */
5284 pud_free(mm, new);
5285 spin_unlock(&mm->page_table_lock);
5286 return 0;
5287}
5288#endif /* __PAGETABLE_PUD_FOLDED */
5289
5290#ifndef __PAGETABLE_PMD_FOLDED
5291/*
5292 * Allocate page middle directory.
5293 * We've already handled the fast-path in-line.
5294 */
5295int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
5296{
5297 spinlock_t *ptl;
5298 pmd_t *new = pmd_alloc_one(mm, address);
5299 if (!new)
5300 return -ENOMEM;
5301
5302 ptl = pud_lock(mm, pud);
5303 if (!pud_present(*pud)) {
5304 mm_inc_nr_pmds(mm);
5305 smp_wmb(); /* See comment in pmd_install() */
5306 pud_populate(mm, pud, new);
5307 } else { /* Another has populated it */
5308 pmd_free(mm, new);
5309 }
5310 spin_unlock(ptl);
5311 return 0;
5312}
5313#endif /* __PAGETABLE_PMD_FOLDED */
5314
5315/**
5316 * follow_pte - look up PTE at a user virtual address
5317 * @mm: the mm_struct of the target address space
5318 * @address: user virtual address
5319 * @ptepp: location to store found PTE
5320 * @ptlp: location to store the lock for the PTE
5321 *
5322 * On a successful return, the pointer to the PTE is stored in @ptepp;
5323 * the corresponding lock is taken and its location is stored in @ptlp.
5324 * The contents of the PTE are only stable until @ptlp is released;
5325 * any further use, if any, must be protected against invalidation
5326 * with MMU notifiers.
5327 *
5328 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
5329 * should be taken for read.
5330 *
5331 * KVM uses this function. While it is arguably less bad than ``follow_pfn``,
5332 * it is not a good general-purpose API.
5333 *
5334 * Return: zero on success, -ve otherwise.
5335 */
5336int follow_pte(struct mm_struct *mm, unsigned long address,
5337 pte_t **ptepp, spinlock_t **ptlp)
5338{
5339 pgd_t *pgd;
5340 p4d_t *p4d;
5341 pud_t *pud;
5342 pmd_t *pmd;
5343 pte_t *ptep;
5344
5345 pgd = pgd_offset(mm, address);
5346 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
5347 goto out;
5348
5349 p4d = p4d_offset(pgd, address);
5350 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
5351 goto out;
5352
5353 pud = pud_offset(p4d, address);
5354 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
5355 goto out;
5356
5357 pmd = pmd_offset(pud, address);
5358 VM_BUG_ON(pmd_trans_huge(*pmd));
5359
5360 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
5361 goto out;
5362
5363 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
5364 if (!pte_present(*ptep))
5365 goto unlock;
5366 *ptepp = ptep;
5367 return 0;
5368unlock:
5369 pte_unmap_unlock(ptep, *ptlp);
5370out:
5371 return -EINVAL;
5372}
5373EXPORT_SYMBOL_GPL(follow_pte);
5374
5375/**
5376 * follow_pfn - look up PFN at a user virtual address
5377 * @vma: memory mapping
5378 * @address: user virtual address
5379 * @pfn: location to store found PFN
5380 *
5381 * Only IO mappings and raw PFN mappings are allowed.
5382 *
5383 * This function does not allow the caller to read the permissions
5384 * of the PTE. Do not use it.
5385 *
5386 * Return: zero and the pfn at @pfn on success, -ve otherwise.
5387 */
5388int follow_pfn(struct vm_area_struct *vma, unsigned long address,
5389 unsigned long *pfn)
5390{
5391 int ret = -EINVAL;
5392 spinlock_t *ptl;
5393 pte_t *ptep;
5394
5395 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5396 return ret;
5397
5398 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
5399 if (ret)
5400 return ret;
5401 *pfn = pte_pfn(*ptep);
5402 pte_unmap_unlock(ptep, ptl);
5403 return 0;
5404}
5405EXPORT_SYMBOL(follow_pfn);
5406
5407#ifdef CONFIG_HAVE_IOREMAP_PROT
5408int follow_phys(struct vm_area_struct *vma,
5409 unsigned long address, unsigned int flags,
5410 unsigned long *prot, resource_size_t *phys)
5411{
5412 int ret = -EINVAL;
5413 pte_t *ptep, pte;
5414 spinlock_t *ptl;
5415
5416 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5417 goto out;
5418
5419 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
5420 goto out;
5421 pte = *ptep;
5422
5423 if ((flags & FOLL_WRITE) && !pte_write(pte))
5424 goto unlock;
5425
5426 *prot = pgprot_val(pte_pgprot(pte));
5427 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5428
5429 ret = 0;
5430unlock:
5431 pte_unmap_unlock(ptep, ptl);
5432out:
5433 return ret;
5434}
5435
5436/**
5437 * generic_access_phys - generic implementation for iomem mmap access
5438 * @vma: the vma to access
5439 * @addr: userspace address, not relative offset within @vma
5440 * @buf: buffer to read/write
5441 * @len: length of transfer
5442 * @write: set to FOLL_WRITE when writing, otherwise reading
5443 *
5444 * This is a generic implementation for &vm_operations_struct.access for an
5445 * iomem mapping. This callback is used by access_process_vm() when the @vma is
5446 * not page based.
5447 */
5448int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
5449 void *buf, int len, int write)
5450{
5451 resource_size_t phys_addr;
5452 unsigned long prot = 0;
5453 void __iomem *maddr;
5454 pte_t *ptep, pte;
5455 spinlock_t *ptl;
5456 int offset = offset_in_page(addr);
5457 int ret = -EINVAL;
5458
5459 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5460 return -EINVAL;
5461
5462retry:
5463 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5464 return -EINVAL;
5465 pte = *ptep;
5466 pte_unmap_unlock(ptep, ptl);
5467
5468 prot = pgprot_val(pte_pgprot(pte));
5469 phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5470
5471 if ((write & FOLL_WRITE) && !pte_write(pte))
5472 return -EINVAL;
5473
5474 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
5475 if (!maddr)
5476 return -ENOMEM;
5477
5478 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5479 goto out_unmap;
5480
5481 if (!pte_same(pte, *ptep)) {
5482 pte_unmap_unlock(ptep, ptl);
5483 iounmap(maddr);
5484
5485 goto retry;
5486 }
5487
5488 if (write)
5489 memcpy_toio(maddr + offset, buf, len);
5490 else
5491 memcpy_fromio(buf, maddr + offset, len);
5492 ret = len;
5493 pte_unmap_unlock(ptep, ptl);
5494out_unmap:
5495 iounmap(maddr);
5496
5497 return ret;
5498}
5499EXPORT_SYMBOL_GPL(generic_access_phys);
5500#endif
5501
5502/*
5503 * Access another process' address space as given in mm.
5504 */
5505int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
5506 int len, unsigned int gup_flags)
5507{
5508 struct vm_area_struct *vma;
5509 void *old_buf = buf;
5510 int write = gup_flags & FOLL_WRITE;
5511
5512 if (mmap_read_lock_killable(mm))
5513 return 0;
5514
5515 /* ignore errors, just check how much was successfully transferred */
5516 while (len) {
5517 int bytes, ret, offset;
5518 void *maddr;
5519 struct page *page = NULL;
5520
5521 ret = get_user_pages_remote(mm, addr, 1,
5522 gup_flags, &page, &vma, NULL);
5523 if (ret <= 0) {
5524#ifndef CONFIG_HAVE_IOREMAP_PROT
5525 break;
5526#else
5527 /*
5528 * Check if this is a VM_IO | VM_PFNMAP VMA, which
5529 * we can access using slightly different code.
5530 */
5531 vma = vma_lookup(mm, addr);
5532 if (!vma)
5533 break;
5534 if (vma->vm_ops && vma->vm_ops->access)
5535 ret = vma->vm_ops->access(vma, addr, buf,
5536 len, write);
5537 if (ret <= 0)
5538 break;
5539 bytes = ret;
5540#endif
5541 } else {
5542 bytes = len;
5543 offset = addr & (PAGE_SIZE-1);
5544 if (bytes > PAGE_SIZE-offset)
5545 bytes = PAGE_SIZE-offset;
5546
5547 maddr = kmap(page);
5548 if (write) {
5549 copy_to_user_page(vma, page, addr,
5550 maddr + offset, buf, bytes);
5551 set_page_dirty_lock(page);
5552 } else {
5553 copy_from_user_page(vma, page, addr,
5554 buf, maddr + offset, bytes);
5555 }
5556 kunmap(page);
5557 put_page(page);
5558 }
5559 len -= bytes;
5560 buf += bytes;
5561 addr += bytes;
5562 }
5563 mmap_read_unlock(mm);
5564
5565 return buf - old_buf;
5566}
5567
5568/**
5569 * access_remote_vm - access another process' address space
5570 * @mm: the mm_struct of the target address space
5571 * @addr: start address to access
5572 * @buf: source or destination buffer
5573 * @len: number of bytes to transfer
5574 * @gup_flags: flags modifying lookup behaviour
5575 *
5576 * The caller must hold a reference on @mm.
5577 *
5578 * Return: number of bytes copied from source to destination.
5579 */
5580int access_remote_vm(struct mm_struct *mm, unsigned long addr,
5581 void *buf, int len, unsigned int gup_flags)
5582{
5583 return __access_remote_vm(mm, addr, buf, len, gup_flags);
5584}
5585
5586/*
5587 * Access another process' address space.
5588 * Source/target buffer must be kernel space,
5589 * Do not walk the page table directly, use get_user_pages
5590 */
5591int access_process_vm(struct task_struct *tsk, unsigned long addr,
5592 void *buf, int len, unsigned int gup_flags)
5593{
5594 struct mm_struct *mm;
5595 int ret;
5596
5597 mm = get_task_mm(tsk);
5598 if (!mm)
5599 return 0;
5600
5601 ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
5602
5603 mmput(mm);
5604
5605 return ret;
5606}
5607EXPORT_SYMBOL_GPL(access_process_vm);
5608
5609/*
5610 * Print the name of a VMA.
5611 */
5612void print_vma_addr(char *prefix, unsigned long ip)
5613{
5614 struct mm_struct *mm = current->mm;
5615 struct vm_area_struct *vma;
5616
5617 /*
5618 * we might be running from an atomic context so we cannot sleep
5619 */
5620 if (!mmap_read_trylock(mm))
5621 return;
5622
5623 vma = find_vma(mm, ip);
5624 if (vma && vma->vm_file) {
5625 struct file *f = vma->vm_file;
5626 char *buf = (char *)__get_free_page(GFP_NOWAIT);
5627 if (buf) {
5628 char *p;
5629
5630 p = file_path(f, buf, PAGE_SIZE);
5631 if (IS_ERR(p))
5632 p = "?";
5633 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
5634 vma->vm_start,
5635 vma->vm_end - vma->vm_start);
5636 free_page((unsigned long)buf);
5637 }
5638 }
5639 mmap_read_unlock(mm);
5640}
5641
5642#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5643void __might_fault(const char *file, int line)
5644{
5645 if (pagefault_disabled())
5646 return;
5647 __might_sleep(file, line);
5648#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5649 if (current->mm)
5650 might_lock_read(¤t->mm->mmap_lock);
5651#endif
5652}
5653EXPORT_SYMBOL(__might_fault);
5654#endif
5655
5656#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
5657/*
5658 * Process all subpages of the specified huge page with the specified
5659 * operation. The target subpage will be processed last to keep its
5660 * cache lines hot.
5661 */
5662static inline void process_huge_page(
5663 unsigned long addr_hint, unsigned int pages_per_huge_page,
5664 void (*process_subpage)(unsigned long addr, int idx, void *arg),
5665 void *arg)
5666{
5667 int i, n, base, l;
5668 unsigned long addr = addr_hint &
5669 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5670
5671 /* Process target subpage last to keep its cache lines hot */
5672 might_sleep();
5673 n = (addr_hint - addr) / PAGE_SIZE;
5674 if (2 * n <= pages_per_huge_page) {
5675 /* If target subpage in first half of huge page */
5676 base = 0;
5677 l = n;
5678 /* Process subpages at the end of huge page */
5679 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
5680 cond_resched();
5681 process_subpage(addr + i * PAGE_SIZE, i, arg);
5682 }
5683 } else {
5684 /* If target subpage in second half of huge page */
5685 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
5686 l = pages_per_huge_page - n;
5687 /* Process subpages at the begin of huge page */
5688 for (i = 0; i < base; i++) {
5689 cond_resched();
5690 process_subpage(addr + i * PAGE_SIZE, i, arg);
5691 }
5692 }
5693 /*
5694 * Process remaining subpages in left-right-left-right pattern
5695 * towards the target subpage
5696 */
5697 for (i = 0; i < l; i++) {
5698 int left_idx = base + i;
5699 int right_idx = base + 2 * l - 1 - i;
5700
5701 cond_resched();
5702 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
5703 cond_resched();
5704 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
5705 }
5706}
5707
5708static void clear_gigantic_page(struct page *page,
5709 unsigned long addr,
5710 unsigned int pages_per_huge_page)
5711{
5712 int i;
5713 struct page *p;
5714
5715 might_sleep();
5716 for (i = 0; i < pages_per_huge_page; i++) {
5717 p = nth_page(page, i);
5718 cond_resched();
5719 clear_user_highpage(p, addr + i * PAGE_SIZE);
5720 }
5721}
5722
5723static void clear_subpage(unsigned long addr, int idx, void *arg)
5724{
5725 struct page *page = arg;
5726
5727 clear_user_highpage(page + idx, addr);
5728}
5729
5730void clear_huge_page(struct page *page,
5731 unsigned long addr_hint, unsigned int pages_per_huge_page)
5732{
5733 unsigned long addr = addr_hint &
5734 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5735
5736 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5737 clear_gigantic_page(page, addr, pages_per_huge_page);
5738 return;
5739 }
5740
5741 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
5742}
5743
5744static void copy_user_gigantic_page(struct page *dst, struct page *src,
5745 unsigned long addr,
5746 struct vm_area_struct *vma,
5747 unsigned int pages_per_huge_page)
5748{
5749 int i;
5750 struct page *dst_base = dst;
5751 struct page *src_base = src;
5752
5753 for (i = 0; i < pages_per_huge_page; i++) {
5754 dst = nth_page(dst_base, i);
5755 src = nth_page(src_base, i);
5756
5757 cond_resched();
5758 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
5759 }
5760}
5761
5762struct copy_subpage_arg {
5763 struct page *dst;
5764 struct page *src;
5765 struct vm_area_struct *vma;
5766};
5767
5768static void copy_subpage(unsigned long addr, int idx, void *arg)
5769{
5770 struct copy_subpage_arg *copy_arg = arg;
5771
5772 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
5773 addr, copy_arg->vma);
5774}
5775
5776void copy_user_huge_page(struct page *dst, struct page *src,
5777 unsigned long addr_hint, struct vm_area_struct *vma,
5778 unsigned int pages_per_huge_page)
5779{
5780 unsigned long addr = addr_hint &
5781 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5782 struct copy_subpage_arg arg = {
5783 .dst = dst,
5784 .src = src,
5785 .vma = vma,
5786 };
5787
5788 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5789 copy_user_gigantic_page(dst, src, addr, vma,
5790 pages_per_huge_page);
5791 return;
5792 }
5793
5794 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
5795}
5796
5797long copy_huge_page_from_user(struct page *dst_page,
5798 const void __user *usr_src,
5799 unsigned int pages_per_huge_page,
5800 bool allow_pagefault)
5801{
5802 void *page_kaddr;
5803 unsigned long i, rc = 0;
5804 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
5805 struct page *subpage;
5806
5807 for (i = 0; i < pages_per_huge_page; i++) {
5808 subpage = nth_page(dst_page, i);
5809 if (allow_pagefault)
5810 page_kaddr = kmap(subpage);
5811 else
5812 page_kaddr = kmap_atomic(subpage);
5813 rc = copy_from_user(page_kaddr,
5814 usr_src + i * PAGE_SIZE, PAGE_SIZE);
5815 if (allow_pagefault)
5816 kunmap(subpage);
5817 else
5818 kunmap_atomic(page_kaddr);
5819
5820 ret_val -= (PAGE_SIZE - rc);
5821 if (rc)
5822 break;
5823
5824 flush_dcache_page(subpage);
5825
5826 cond_resched();
5827 }
5828 return ret_val;
5829}
5830#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
5831
5832#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
5833
5834static struct kmem_cache *page_ptl_cachep;
5835
5836void __init ptlock_cache_init(void)
5837{
5838 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
5839 SLAB_PANIC, NULL);
5840}
5841
5842bool ptlock_alloc(struct page *page)
5843{
5844 spinlock_t *ptl;
5845
5846 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
5847 if (!ptl)
5848 return false;
5849 page->ptl = ptl;
5850 return true;
5851}
5852
5853void ptlock_free(struct page *page)
5854{
5855 kmem_cache_free(page_ptl_cachep, page->ptl);
5856}
5857#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/memory.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 */
7
8/*
9 * demand-loading started 01.12.91 - seems it is high on the list of
10 * things wanted, and it should be easy to implement. - Linus
11 */
12
13/*
14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 * pages started 02.12.91, seems to work. - Linus.
16 *
17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 * would have taken more than the 6M I have free, but it worked well as
19 * far as I could see.
20 *
21 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22 */
23
24/*
25 * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 * thought has to go into this. Oh, well..
27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 * Found it. Everything seems to work now.
29 * 20.12.91 - Ok, making the swap-device changeable like the root.
30 */
31
32/*
33 * 05.04.94 - Multi-page memory management added for v1.1.
34 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 *
36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 * (Gerhard.Wichert@pdb.siemens.de)
38 *
39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40 */
41
42#include <linux/kernel_stat.h>
43#include <linux/mm.h>
44#include <linux/mm_inline.h>
45#include <linux/sched/mm.h>
46#include <linux/sched/numa_balancing.h>
47#include <linux/sched/task.h>
48#include <linux/hugetlb.h>
49#include <linux/mman.h>
50#include <linux/swap.h>
51#include <linux/highmem.h>
52#include <linux/pagemap.h>
53#include <linux/memremap.h>
54#include <linux/kmsan.h>
55#include <linux/ksm.h>
56#include <linux/rmap.h>
57#include <linux/export.h>
58#include <linux/delayacct.h>
59#include <linux/init.h>
60#include <linux/pfn_t.h>
61#include <linux/writeback.h>
62#include <linux/memcontrol.h>
63#include <linux/mmu_notifier.h>
64#include <linux/swapops.h>
65#include <linux/elf.h>
66#include <linux/gfp.h>
67#include <linux/migrate.h>
68#include <linux/string.h>
69#include <linux/memory-tiers.h>
70#include <linux/debugfs.h>
71#include <linux/userfaultfd_k.h>
72#include <linux/dax.h>
73#include <linux/oom.h>
74#include <linux/numa.h>
75#include <linux/perf_event.h>
76#include <linux/ptrace.h>
77#include <linux/vmalloc.h>
78#include <linux/sched/sysctl.h>
79
80#include <trace/events/kmem.h>
81
82#include <asm/io.h>
83#include <asm/mmu_context.h>
84#include <asm/pgalloc.h>
85#include <linux/uaccess.h>
86#include <asm/tlb.h>
87#include <asm/tlbflush.h>
88
89#include "pgalloc-track.h"
90#include "internal.h"
91#include "swap.h"
92
93#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
94#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
95#endif
96
97#ifndef CONFIG_NUMA
98unsigned long max_mapnr;
99EXPORT_SYMBOL(max_mapnr);
100
101struct page *mem_map;
102EXPORT_SYMBOL(mem_map);
103#endif
104
105static vm_fault_t do_fault(struct vm_fault *vmf);
106static vm_fault_t do_anonymous_page(struct vm_fault *vmf);
107static bool vmf_pte_changed(struct vm_fault *vmf);
108
109/*
110 * Return true if the original pte was a uffd-wp pte marker (so the pte was
111 * wr-protected).
112 */
113static __always_inline bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf)
114{
115 if (!userfaultfd_wp(vmf->vma))
116 return false;
117 if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID))
118 return false;
119
120 return pte_marker_uffd_wp(vmf->orig_pte);
121}
122
123/*
124 * A number of key systems in x86 including ioremap() rely on the assumption
125 * that high_memory defines the upper bound on direct map memory, then end
126 * of ZONE_NORMAL.
127 */
128void *high_memory;
129EXPORT_SYMBOL(high_memory);
130
131/*
132 * Randomize the address space (stacks, mmaps, brk, etc.).
133 *
134 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
135 * as ancient (libc5 based) binaries can segfault. )
136 */
137int randomize_va_space __read_mostly =
138#ifdef CONFIG_COMPAT_BRK
139 1;
140#else
141 2;
142#endif
143
144#ifndef arch_wants_old_prefaulted_pte
145static inline bool arch_wants_old_prefaulted_pte(void)
146{
147 /*
148 * Transitioning a PTE from 'old' to 'young' can be expensive on
149 * some architectures, even if it's performed in hardware. By
150 * default, "false" means prefaulted entries will be 'young'.
151 */
152 return false;
153}
154#endif
155
156static int __init disable_randmaps(char *s)
157{
158 randomize_va_space = 0;
159 return 1;
160}
161__setup("norandmaps", disable_randmaps);
162
163unsigned long zero_pfn __read_mostly;
164EXPORT_SYMBOL(zero_pfn);
165
166unsigned long highest_memmap_pfn __read_mostly;
167
168/*
169 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
170 */
171static int __init init_zero_pfn(void)
172{
173 zero_pfn = page_to_pfn(ZERO_PAGE(0));
174 return 0;
175}
176early_initcall(init_zero_pfn);
177
178void mm_trace_rss_stat(struct mm_struct *mm, int member)
179{
180 trace_rss_stat(mm, member);
181}
182
183/*
184 * Note: this doesn't free the actual pages themselves. That
185 * has been handled earlier when unmapping all the memory regions.
186 */
187static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
188 unsigned long addr)
189{
190 pgtable_t token = pmd_pgtable(*pmd);
191 pmd_clear(pmd);
192 pte_free_tlb(tlb, token, addr);
193 mm_dec_nr_ptes(tlb->mm);
194}
195
196static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
197 unsigned long addr, unsigned long end,
198 unsigned long floor, unsigned long ceiling)
199{
200 pmd_t *pmd;
201 unsigned long next;
202 unsigned long start;
203
204 start = addr;
205 pmd = pmd_offset(pud, addr);
206 do {
207 next = pmd_addr_end(addr, end);
208 if (pmd_none_or_clear_bad(pmd))
209 continue;
210 free_pte_range(tlb, pmd, addr);
211 } while (pmd++, addr = next, addr != end);
212
213 start &= PUD_MASK;
214 if (start < floor)
215 return;
216 if (ceiling) {
217 ceiling &= PUD_MASK;
218 if (!ceiling)
219 return;
220 }
221 if (end - 1 > ceiling - 1)
222 return;
223
224 pmd = pmd_offset(pud, start);
225 pud_clear(pud);
226 pmd_free_tlb(tlb, pmd, start);
227 mm_dec_nr_pmds(tlb->mm);
228}
229
230static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
231 unsigned long addr, unsigned long end,
232 unsigned long floor, unsigned long ceiling)
233{
234 pud_t *pud;
235 unsigned long next;
236 unsigned long start;
237
238 start = addr;
239 pud = pud_offset(p4d, addr);
240 do {
241 next = pud_addr_end(addr, end);
242 if (pud_none_or_clear_bad(pud))
243 continue;
244 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
245 } while (pud++, addr = next, addr != end);
246
247 start &= P4D_MASK;
248 if (start < floor)
249 return;
250 if (ceiling) {
251 ceiling &= P4D_MASK;
252 if (!ceiling)
253 return;
254 }
255 if (end - 1 > ceiling - 1)
256 return;
257
258 pud = pud_offset(p4d, start);
259 p4d_clear(p4d);
260 pud_free_tlb(tlb, pud, start);
261 mm_dec_nr_puds(tlb->mm);
262}
263
264static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
265 unsigned long addr, unsigned long end,
266 unsigned long floor, unsigned long ceiling)
267{
268 p4d_t *p4d;
269 unsigned long next;
270 unsigned long start;
271
272 start = addr;
273 p4d = p4d_offset(pgd, addr);
274 do {
275 next = p4d_addr_end(addr, end);
276 if (p4d_none_or_clear_bad(p4d))
277 continue;
278 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
279 } while (p4d++, addr = next, addr != end);
280
281 start &= PGDIR_MASK;
282 if (start < floor)
283 return;
284 if (ceiling) {
285 ceiling &= PGDIR_MASK;
286 if (!ceiling)
287 return;
288 }
289 if (end - 1 > ceiling - 1)
290 return;
291
292 p4d = p4d_offset(pgd, start);
293 pgd_clear(pgd);
294 p4d_free_tlb(tlb, p4d, start);
295}
296
297/*
298 * This function frees user-level page tables of a process.
299 */
300void free_pgd_range(struct mmu_gather *tlb,
301 unsigned long addr, unsigned long end,
302 unsigned long floor, unsigned long ceiling)
303{
304 pgd_t *pgd;
305 unsigned long next;
306
307 /*
308 * The next few lines have given us lots of grief...
309 *
310 * Why are we testing PMD* at this top level? Because often
311 * there will be no work to do at all, and we'd prefer not to
312 * go all the way down to the bottom just to discover that.
313 *
314 * Why all these "- 1"s? Because 0 represents both the bottom
315 * of the address space and the top of it (using -1 for the
316 * top wouldn't help much: the masks would do the wrong thing).
317 * The rule is that addr 0 and floor 0 refer to the bottom of
318 * the address space, but end 0 and ceiling 0 refer to the top
319 * Comparisons need to use "end - 1" and "ceiling - 1" (though
320 * that end 0 case should be mythical).
321 *
322 * Wherever addr is brought up or ceiling brought down, we must
323 * be careful to reject "the opposite 0" before it confuses the
324 * subsequent tests. But what about where end is brought down
325 * by PMD_SIZE below? no, end can't go down to 0 there.
326 *
327 * Whereas we round start (addr) and ceiling down, by different
328 * masks at different levels, in order to test whether a table
329 * now has no other vmas using it, so can be freed, we don't
330 * bother to round floor or end up - the tests don't need that.
331 */
332
333 addr &= PMD_MASK;
334 if (addr < floor) {
335 addr += PMD_SIZE;
336 if (!addr)
337 return;
338 }
339 if (ceiling) {
340 ceiling &= PMD_MASK;
341 if (!ceiling)
342 return;
343 }
344 if (end - 1 > ceiling - 1)
345 end -= PMD_SIZE;
346 if (addr > end - 1)
347 return;
348 /*
349 * We add page table cache pages with PAGE_SIZE,
350 * (see pte_free_tlb()), flush the tlb if we need
351 */
352 tlb_change_page_size(tlb, PAGE_SIZE);
353 pgd = pgd_offset(tlb->mm, addr);
354 do {
355 next = pgd_addr_end(addr, end);
356 if (pgd_none_or_clear_bad(pgd))
357 continue;
358 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
359 } while (pgd++, addr = next, addr != end);
360}
361
362void free_pgtables(struct mmu_gather *tlb, struct ma_state *mas,
363 struct vm_area_struct *vma, unsigned long floor,
364 unsigned long ceiling, bool mm_wr_locked)
365{
366 struct unlink_vma_file_batch vb;
367
368 do {
369 unsigned long addr = vma->vm_start;
370 struct vm_area_struct *next;
371
372 /*
373 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
374 * be 0. This will underflow and is okay.
375 */
376 next = mas_find(mas, ceiling - 1);
377 if (unlikely(xa_is_zero(next)))
378 next = NULL;
379
380 /*
381 * Hide vma from rmap and truncate_pagecache before freeing
382 * pgtables
383 */
384 if (mm_wr_locked)
385 vma_start_write(vma);
386 unlink_anon_vmas(vma);
387
388 if (is_vm_hugetlb_page(vma)) {
389 unlink_file_vma(vma);
390 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
391 floor, next ? next->vm_start : ceiling);
392 } else {
393 unlink_file_vma_batch_init(&vb);
394 unlink_file_vma_batch_add(&vb, vma);
395
396 /*
397 * Optimization: gather nearby vmas into one call down
398 */
399 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
400 && !is_vm_hugetlb_page(next)) {
401 vma = next;
402 next = mas_find(mas, ceiling - 1);
403 if (unlikely(xa_is_zero(next)))
404 next = NULL;
405 if (mm_wr_locked)
406 vma_start_write(vma);
407 unlink_anon_vmas(vma);
408 unlink_file_vma_batch_add(&vb, vma);
409 }
410 unlink_file_vma_batch_final(&vb);
411 free_pgd_range(tlb, addr, vma->vm_end,
412 floor, next ? next->vm_start : ceiling);
413 }
414 vma = next;
415 } while (vma);
416}
417
418void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
419{
420 spinlock_t *ptl = pmd_lock(mm, pmd);
421
422 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
423 mm_inc_nr_ptes(mm);
424 /*
425 * Ensure all pte setup (eg. pte page lock and page clearing) are
426 * visible before the pte is made visible to other CPUs by being
427 * put into page tables.
428 *
429 * The other side of the story is the pointer chasing in the page
430 * table walking code (when walking the page table without locking;
431 * ie. most of the time). Fortunately, these data accesses consist
432 * of a chain of data-dependent loads, meaning most CPUs (alpha
433 * being the notable exception) will already guarantee loads are
434 * seen in-order. See the alpha page table accessors for the
435 * smp_rmb() barriers in page table walking code.
436 */
437 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
438 pmd_populate(mm, pmd, *pte);
439 *pte = NULL;
440 }
441 spin_unlock(ptl);
442}
443
444int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
445{
446 pgtable_t new = pte_alloc_one(mm);
447 if (!new)
448 return -ENOMEM;
449
450 pmd_install(mm, pmd, &new);
451 if (new)
452 pte_free(mm, new);
453 return 0;
454}
455
456int __pte_alloc_kernel(pmd_t *pmd)
457{
458 pte_t *new = pte_alloc_one_kernel(&init_mm);
459 if (!new)
460 return -ENOMEM;
461
462 spin_lock(&init_mm.page_table_lock);
463 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
464 smp_wmb(); /* See comment in pmd_install() */
465 pmd_populate_kernel(&init_mm, pmd, new);
466 new = NULL;
467 }
468 spin_unlock(&init_mm.page_table_lock);
469 if (new)
470 pte_free_kernel(&init_mm, new);
471 return 0;
472}
473
474static inline void init_rss_vec(int *rss)
475{
476 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
477}
478
479static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
480{
481 int i;
482
483 for (i = 0; i < NR_MM_COUNTERS; i++)
484 if (rss[i])
485 add_mm_counter(mm, i, rss[i]);
486}
487
488/*
489 * This function is called to print an error when a bad pte
490 * is found. For example, we might have a PFN-mapped pte in
491 * a region that doesn't allow it.
492 *
493 * The calling function must still handle the error.
494 */
495static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
496 pte_t pte, struct page *page)
497{
498 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
499 p4d_t *p4d = p4d_offset(pgd, addr);
500 pud_t *pud = pud_offset(p4d, addr);
501 pmd_t *pmd = pmd_offset(pud, addr);
502 struct address_space *mapping;
503 pgoff_t index;
504 static unsigned long resume;
505 static unsigned long nr_shown;
506 static unsigned long nr_unshown;
507
508 /*
509 * Allow a burst of 60 reports, then keep quiet for that minute;
510 * or allow a steady drip of one report per second.
511 */
512 if (nr_shown == 60) {
513 if (time_before(jiffies, resume)) {
514 nr_unshown++;
515 return;
516 }
517 if (nr_unshown) {
518 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
519 nr_unshown);
520 nr_unshown = 0;
521 }
522 nr_shown = 0;
523 }
524 if (nr_shown++ == 0)
525 resume = jiffies + 60 * HZ;
526
527 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
528 index = linear_page_index(vma, addr);
529
530 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
531 current->comm,
532 (long long)pte_val(pte), (long long)pmd_val(*pmd));
533 if (page)
534 dump_page(page, "bad pte");
535 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
536 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
537 pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
538 vma->vm_file,
539 vma->vm_ops ? vma->vm_ops->fault : NULL,
540 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
541 mapping ? mapping->a_ops->read_folio : NULL);
542 dump_stack();
543 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
544}
545
546/*
547 * vm_normal_page -- This function gets the "struct page" associated with a pte.
548 *
549 * "Special" mappings do not wish to be associated with a "struct page" (either
550 * it doesn't exist, or it exists but they don't want to touch it). In this
551 * case, NULL is returned here. "Normal" mappings do have a struct page.
552 *
553 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
554 * pte bit, in which case this function is trivial. Secondly, an architecture
555 * may not have a spare pte bit, which requires a more complicated scheme,
556 * described below.
557 *
558 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
559 * special mapping (even if there are underlying and valid "struct pages").
560 * COWed pages of a VM_PFNMAP are always normal.
561 *
562 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
563 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
564 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
565 * mapping will always honor the rule
566 *
567 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
568 *
569 * And for normal mappings this is false.
570 *
571 * This restricts such mappings to be a linear translation from virtual address
572 * to pfn. To get around this restriction, we allow arbitrary mappings so long
573 * as the vma is not a COW mapping; in that case, we know that all ptes are
574 * special (because none can have been COWed).
575 *
576 *
577 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
578 *
579 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
580 * page" backing, however the difference is that _all_ pages with a struct
581 * page (that is, those where pfn_valid is true) are refcounted and considered
582 * normal pages by the VM. The only exception are zeropages, which are
583 * *never* refcounted.
584 *
585 * The disadvantage is that pages are refcounted (which can be slower and
586 * simply not an option for some PFNMAP users). The advantage is that we
587 * don't have to follow the strict linearity rule of PFNMAP mappings in
588 * order to support COWable mappings.
589 *
590 */
591struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
592 pte_t pte)
593{
594 unsigned long pfn = pte_pfn(pte);
595
596 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
597 if (likely(!pte_special(pte)))
598 goto check_pfn;
599 if (vma->vm_ops && vma->vm_ops->find_special_page)
600 return vma->vm_ops->find_special_page(vma, addr);
601 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
602 return NULL;
603 if (is_zero_pfn(pfn))
604 return NULL;
605 if (pte_devmap(pte))
606 /*
607 * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
608 * and will have refcounts incremented on their struct pages
609 * when they are inserted into PTEs, thus they are safe to
610 * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
611 * do not have refcounts. Example of legacy ZONE_DEVICE is
612 * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
613 */
614 return NULL;
615
616 print_bad_pte(vma, addr, pte, NULL);
617 return NULL;
618 }
619
620 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
621
622 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
623 if (vma->vm_flags & VM_MIXEDMAP) {
624 if (!pfn_valid(pfn))
625 return NULL;
626 if (is_zero_pfn(pfn))
627 return NULL;
628 goto out;
629 } else {
630 unsigned long off;
631 off = (addr - vma->vm_start) >> PAGE_SHIFT;
632 if (pfn == vma->vm_pgoff + off)
633 return NULL;
634 if (!is_cow_mapping(vma->vm_flags))
635 return NULL;
636 }
637 }
638
639 if (is_zero_pfn(pfn))
640 return NULL;
641
642check_pfn:
643 if (unlikely(pfn > highest_memmap_pfn)) {
644 print_bad_pte(vma, addr, pte, NULL);
645 return NULL;
646 }
647
648 /*
649 * NOTE! We still have PageReserved() pages in the page tables.
650 * eg. VDSO mappings can cause them to exist.
651 */
652out:
653 VM_WARN_ON_ONCE(is_zero_pfn(pfn));
654 return pfn_to_page(pfn);
655}
656
657struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr,
658 pte_t pte)
659{
660 struct page *page = vm_normal_page(vma, addr, pte);
661
662 if (page)
663 return page_folio(page);
664 return NULL;
665}
666
667#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
668struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
669 pmd_t pmd)
670{
671 unsigned long pfn = pmd_pfn(pmd);
672
673 /* Currently it's only used for huge pfnmaps */
674 if (unlikely(pmd_special(pmd)))
675 return NULL;
676
677 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
678 if (vma->vm_flags & VM_MIXEDMAP) {
679 if (!pfn_valid(pfn))
680 return NULL;
681 goto out;
682 } else {
683 unsigned long off;
684 off = (addr - vma->vm_start) >> PAGE_SHIFT;
685 if (pfn == vma->vm_pgoff + off)
686 return NULL;
687 if (!is_cow_mapping(vma->vm_flags))
688 return NULL;
689 }
690 }
691
692 if (pmd_devmap(pmd))
693 return NULL;
694 if (is_huge_zero_pmd(pmd))
695 return NULL;
696 if (unlikely(pfn > highest_memmap_pfn))
697 return NULL;
698
699 /*
700 * NOTE! We still have PageReserved() pages in the page tables.
701 * eg. VDSO mappings can cause them to exist.
702 */
703out:
704 return pfn_to_page(pfn);
705}
706
707struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma,
708 unsigned long addr, pmd_t pmd)
709{
710 struct page *page = vm_normal_page_pmd(vma, addr, pmd);
711
712 if (page)
713 return page_folio(page);
714 return NULL;
715}
716#endif
717
718static void restore_exclusive_pte(struct vm_area_struct *vma,
719 struct page *page, unsigned long address,
720 pte_t *ptep)
721{
722 struct folio *folio = page_folio(page);
723 pte_t orig_pte;
724 pte_t pte;
725 swp_entry_t entry;
726
727 orig_pte = ptep_get(ptep);
728 pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
729 if (pte_swp_soft_dirty(orig_pte))
730 pte = pte_mksoft_dirty(pte);
731
732 entry = pte_to_swp_entry(orig_pte);
733 if (pte_swp_uffd_wp(orig_pte))
734 pte = pte_mkuffd_wp(pte);
735 else if (is_writable_device_exclusive_entry(entry))
736 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
737
738 VM_BUG_ON_FOLIO(pte_write(pte) && (!folio_test_anon(folio) &&
739 PageAnonExclusive(page)), folio);
740
741 /*
742 * No need to take a page reference as one was already
743 * created when the swap entry was made.
744 */
745 if (folio_test_anon(folio))
746 folio_add_anon_rmap_pte(folio, page, vma, address, RMAP_NONE);
747 else
748 /*
749 * Currently device exclusive access only supports anonymous
750 * memory so the entry shouldn't point to a filebacked page.
751 */
752 WARN_ON_ONCE(1);
753
754 set_pte_at(vma->vm_mm, address, ptep, pte);
755
756 /*
757 * No need to invalidate - it was non-present before. However
758 * secondary CPUs may have mappings that need invalidating.
759 */
760 update_mmu_cache(vma, address, ptep);
761}
762
763/*
764 * Tries to restore an exclusive pte if the page lock can be acquired without
765 * sleeping.
766 */
767static int
768try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
769 unsigned long addr)
770{
771 swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte));
772 struct page *page = pfn_swap_entry_to_page(entry);
773
774 if (trylock_page(page)) {
775 restore_exclusive_pte(vma, page, addr, src_pte);
776 unlock_page(page);
777 return 0;
778 }
779
780 return -EBUSY;
781}
782
783/*
784 * copy one vm_area from one task to the other. Assumes the page tables
785 * already present in the new task to be cleared in the whole range
786 * covered by this vma.
787 */
788
789static unsigned long
790copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
791 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
792 struct vm_area_struct *src_vma, unsigned long addr, int *rss)
793{
794 unsigned long vm_flags = dst_vma->vm_flags;
795 pte_t orig_pte = ptep_get(src_pte);
796 pte_t pte = orig_pte;
797 struct folio *folio;
798 struct page *page;
799 swp_entry_t entry = pte_to_swp_entry(orig_pte);
800
801 if (likely(!non_swap_entry(entry))) {
802 if (swap_duplicate(entry) < 0)
803 return -EIO;
804
805 /* make sure dst_mm is on swapoff's mmlist. */
806 if (unlikely(list_empty(&dst_mm->mmlist))) {
807 spin_lock(&mmlist_lock);
808 if (list_empty(&dst_mm->mmlist))
809 list_add(&dst_mm->mmlist,
810 &src_mm->mmlist);
811 spin_unlock(&mmlist_lock);
812 }
813 /* Mark the swap entry as shared. */
814 if (pte_swp_exclusive(orig_pte)) {
815 pte = pte_swp_clear_exclusive(orig_pte);
816 set_pte_at(src_mm, addr, src_pte, pte);
817 }
818 rss[MM_SWAPENTS]++;
819 } else if (is_migration_entry(entry)) {
820 folio = pfn_swap_entry_folio(entry);
821
822 rss[mm_counter(folio)]++;
823
824 if (!is_readable_migration_entry(entry) &&
825 is_cow_mapping(vm_flags)) {
826 /*
827 * COW mappings require pages in both parent and child
828 * to be set to read. A previously exclusive entry is
829 * now shared.
830 */
831 entry = make_readable_migration_entry(
832 swp_offset(entry));
833 pte = swp_entry_to_pte(entry);
834 if (pte_swp_soft_dirty(orig_pte))
835 pte = pte_swp_mksoft_dirty(pte);
836 if (pte_swp_uffd_wp(orig_pte))
837 pte = pte_swp_mkuffd_wp(pte);
838 set_pte_at(src_mm, addr, src_pte, pte);
839 }
840 } else if (is_device_private_entry(entry)) {
841 page = pfn_swap_entry_to_page(entry);
842 folio = page_folio(page);
843
844 /*
845 * Update rss count even for unaddressable pages, as
846 * they should treated just like normal pages in this
847 * respect.
848 *
849 * We will likely want to have some new rss counters
850 * for unaddressable pages, at some point. But for now
851 * keep things as they are.
852 */
853 folio_get(folio);
854 rss[mm_counter(folio)]++;
855 /* Cannot fail as these pages cannot get pinned. */
856 folio_try_dup_anon_rmap_pte(folio, page, src_vma);
857
858 /*
859 * We do not preserve soft-dirty information, because so
860 * far, checkpoint/restore is the only feature that
861 * requires that. And checkpoint/restore does not work
862 * when a device driver is involved (you cannot easily
863 * save and restore device driver state).
864 */
865 if (is_writable_device_private_entry(entry) &&
866 is_cow_mapping(vm_flags)) {
867 entry = make_readable_device_private_entry(
868 swp_offset(entry));
869 pte = swp_entry_to_pte(entry);
870 if (pte_swp_uffd_wp(orig_pte))
871 pte = pte_swp_mkuffd_wp(pte);
872 set_pte_at(src_mm, addr, src_pte, pte);
873 }
874 } else if (is_device_exclusive_entry(entry)) {
875 /*
876 * Make device exclusive entries present by restoring the
877 * original entry then copying as for a present pte. Device
878 * exclusive entries currently only support private writable
879 * (ie. COW) mappings.
880 */
881 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
882 if (try_restore_exclusive_pte(src_pte, src_vma, addr))
883 return -EBUSY;
884 return -ENOENT;
885 } else if (is_pte_marker_entry(entry)) {
886 pte_marker marker = copy_pte_marker(entry, dst_vma);
887
888 if (marker)
889 set_pte_at(dst_mm, addr, dst_pte,
890 make_pte_marker(marker));
891 return 0;
892 }
893 if (!userfaultfd_wp(dst_vma))
894 pte = pte_swp_clear_uffd_wp(pte);
895 set_pte_at(dst_mm, addr, dst_pte, pte);
896 return 0;
897}
898
899/*
900 * Copy a present and normal page.
901 *
902 * NOTE! The usual case is that this isn't required;
903 * instead, the caller can just increase the page refcount
904 * and re-use the pte the traditional way.
905 *
906 * And if we need a pre-allocated page but don't yet have
907 * one, return a negative error to let the preallocation
908 * code know so that it can do so outside the page table
909 * lock.
910 */
911static inline int
912copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
913 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
914 struct folio **prealloc, struct page *page)
915{
916 struct folio *new_folio;
917 pte_t pte;
918
919 new_folio = *prealloc;
920 if (!new_folio)
921 return -EAGAIN;
922
923 /*
924 * We have a prealloc page, all good! Take it
925 * over and copy the page & arm it.
926 */
927
928 if (copy_mc_user_highpage(&new_folio->page, page, addr, src_vma))
929 return -EHWPOISON;
930
931 *prealloc = NULL;
932 __folio_mark_uptodate(new_folio);
933 folio_add_new_anon_rmap(new_folio, dst_vma, addr, RMAP_EXCLUSIVE);
934 folio_add_lru_vma(new_folio, dst_vma);
935 rss[MM_ANONPAGES]++;
936
937 /* All done, just insert the new page copy in the child */
938 pte = mk_pte(&new_folio->page, dst_vma->vm_page_prot);
939 pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
940 if (userfaultfd_pte_wp(dst_vma, ptep_get(src_pte)))
941 /* Uffd-wp needs to be delivered to dest pte as well */
942 pte = pte_mkuffd_wp(pte);
943 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
944 return 0;
945}
946
947static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma,
948 struct vm_area_struct *src_vma, pte_t *dst_pte, pte_t *src_pte,
949 pte_t pte, unsigned long addr, int nr)
950{
951 struct mm_struct *src_mm = src_vma->vm_mm;
952
953 /* If it's a COW mapping, write protect it both processes. */
954 if (is_cow_mapping(src_vma->vm_flags) && pte_write(pte)) {
955 wrprotect_ptes(src_mm, addr, src_pte, nr);
956 pte = pte_wrprotect(pte);
957 }
958
959 /* If it's a shared mapping, mark it clean in the child. */
960 if (src_vma->vm_flags & VM_SHARED)
961 pte = pte_mkclean(pte);
962 pte = pte_mkold(pte);
963
964 if (!userfaultfd_wp(dst_vma))
965 pte = pte_clear_uffd_wp(pte);
966
967 set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr);
968}
969
970/*
971 * Copy one present PTE, trying to batch-process subsequent PTEs that map
972 * consecutive pages of the same folio by copying them as well.
973 *
974 * Returns -EAGAIN if one preallocated page is required to copy the next PTE.
975 * Otherwise, returns the number of copied PTEs (at least 1).
976 */
977static inline int
978copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
979 pte_t *dst_pte, pte_t *src_pte, pte_t pte, unsigned long addr,
980 int max_nr, int *rss, struct folio **prealloc)
981{
982 struct page *page;
983 struct folio *folio;
984 bool any_writable;
985 fpb_t flags = 0;
986 int err, nr;
987
988 page = vm_normal_page(src_vma, addr, pte);
989 if (unlikely(!page))
990 goto copy_pte;
991
992 folio = page_folio(page);
993
994 /*
995 * If we likely have to copy, just don't bother with batching. Make
996 * sure that the common "small folio" case is as fast as possible
997 * by keeping the batching logic separate.
998 */
999 if (unlikely(!*prealloc && folio_test_large(folio) && max_nr != 1)) {
1000 if (src_vma->vm_flags & VM_SHARED)
1001 flags |= FPB_IGNORE_DIRTY;
1002 if (!vma_soft_dirty_enabled(src_vma))
1003 flags |= FPB_IGNORE_SOFT_DIRTY;
1004
1005 nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags,
1006 &any_writable, NULL, NULL);
1007 folio_ref_add(folio, nr);
1008 if (folio_test_anon(folio)) {
1009 if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page,
1010 nr, src_vma))) {
1011 folio_ref_sub(folio, nr);
1012 return -EAGAIN;
1013 }
1014 rss[MM_ANONPAGES] += nr;
1015 VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
1016 } else {
1017 folio_dup_file_rmap_ptes(folio, page, nr);
1018 rss[mm_counter_file(folio)] += nr;
1019 }
1020 if (any_writable)
1021 pte = pte_mkwrite(pte, src_vma);
1022 __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte,
1023 addr, nr);
1024 return nr;
1025 }
1026
1027 folio_get(folio);
1028 if (folio_test_anon(folio)) {
1029 /*
1030 * If this page may have been pinned by the parent process,
1031 * copy the page immediately for the child so that we'll always
1032 * guarantee the pinned page won't be randomly replaced in the
1033 * future.
1034 */
1035 if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, src_vma))) {
1036 /* Page may be pinned, we have to copy. */
1037 folio_put(folio);
1038 err = copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
1039 addr, rss, prealloc, page);
1040 return err ? err : 1;
1041 }
1042 rss[MM_ANONPAGES]++;
1043 VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
1044 } else {
1045 folio_dup_file_rmap_pte(folio, page);
1046 rss[mm_counter_file(folio)]++;
1047 }
1048
1049copy_pte:
1050 __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte, addr, 1);
1051 return 1;
1052}
1053
1054static inline struct folio *folio_prealloc(struct mm_struct *src_mm,
1055 struct vm_area_struct *vma, unsigned long addr, bool need_zero)
1056{
1057 struct folio *new_folio;
1058
1059 if (need_zero)
1060 new_folio = vma_alloc_zeroed_movable_folio(vma, addr);
1061 else
1062 new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, addr);
1063
1064 if (!new_folio)
1065 return NULL;
1066
1067 if (mem_cgroup_charge(new_folio, src_mm, GFP_KERNEL)) {
1068 folio_put(new_folio);
1069 return NULL;
1070 }
1071 folio_throttle_swaprate(new_folio, GFP_KERNEL);
1072
1073 return new_folio;
1074}
1075
1076static int
1077copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1078 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1079 unsigned long end)
1080{
1081 struct mm_struct *dst_mm = dst_vma->vm_mm;
1082 struct mm_struct *src_mm = src_vma->vm_mm;
1083 pte_t *orig_src_pte, *orig_dst_pte;
1084 pte_t *src_pte, *dst_pte;
1085 pmd_t dummy_pmdval;
1086 pte_t ptent;
1087 spinlock_t *src_ptl, *dst_ptl;
1088 int progress, max_nr, ret = 0;
1089 int rss[NR_MM_COUNTERS];
1090 swp_entry_t entry = (swp_entry_t){0};
1091 struct folio *prealloc = NULL;
1092 int nr;
1093
1094again:
1095 progress = 0;
1096 init_rss_vec(rss);
1097
1098 /*
1099 * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the
1100 * error handling here, assume that exclusive mmap_lock on dst and src
1101 * protects anon from unexpected THP transitions; with shmem and file
1102 * protected by mmap_lock-less collapse skipping areas with anon_vma
1103 * (whereas vma_needs_copy() skips areas without anon_vma). A rework
1104 * can remove such assumptions later, but this is good enough for now.
1105 */
1106 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1107 if (!dst_pte) {
1108 ret = -ENOMEM;
1109 goto out;
1110 }
1111
1112 /*
1113 * We already hold the exclusive mmap_lock, the copy_pte_range() and
1114 * retract_page_tables() are using vma->anon_vma to be exclusive, so
1115 * the PTE page is stable, and there is no need to get pmdval and do
1116 * pmd_same() check.
1117 */
1118 src_pte = pte_offset_map_rw_nolock(src_mm, src_pmd, addr, &dummy_pmdval,
1119 &src_ptl);
1120 if (!src_pte) {
1121 pte_unmap_unlock(dst_pte, dst_ptl);
1122 /* ret == 0 */
1123 goto out;
1124 }
1125 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1126 orig_src_pte = src_pte;
1127 orig_dst_pte = dst_pte;
1128 arch_enter_lazy_mmu_mode();
1129
1130 do {
1131 nr = 1;
1132
1133 /*
1134 * We are holding two locks at this point - either of them
1135 * could generate latencies in another task on another CPU.
1136 */
1137 if (progress >= 32) {
1138 progress = 0;
1139 if (need_resched() ||
1140 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1141 break;
1142 }
1143 ptent = ptep_get(src_pte);
1144 if (pte_none(ptent)) {
1145 progress++;
1146 continue;
1147 }
1148 if (unlikely(!pte_present(ptent))) {
1149 ret = copy_nonpresent_pte(dst_mm, src_mm,
1150 dst_pte, src_pte,
1151 dst_vma, src_vma,
1152 addr, rss);
1153 if (ret == -EIO) {
1154 entry = pte_to_swp_entry(ptep_get(src_pte));
1155 break;
1156 } else if (ret == -EBUSY) {
1157 break;
1158 } else if (!ret) {
1159 progress += 8;
1160 continue;
1161 }
1162 ptent = ptep_get(src_pte);
1163 VM_WARN_ON_ONCE(!pte_present(ptent));
1164
1165 /*
1166 * Device exclusive entry restored, continue by copying
1167 * the now present pte.
1168 */
1169 WARN_ON_ONCE(ret != -ENOENT);
1170 }
1171 /* copy_present_ptes() will clear `*prealloc' if consumed */
1172 max_nr = (end - addr) / PAGE_SIZE;
1173 ret = copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte,
1174 ptent, addr, max_nr, rss, &prealloc);
1175 /*
1176 * If we need a pre-allocated page for this pte, drop the
1177 * locks, allocate, and try again.
1178 * If copy failed due to hwpoison in source page, break out.
1179 */
1180 if (unlikely(ret == -EAGAIN || ret == -EHWPOISON))
1181 break;
1182 if (unlikely(prealloc)) {
1183 /*
1184 * pre-alloc page cannot be reused by next time so as
1185 * to strictly follow mempolicy (e.g., alloc_page_vma()
1186 * will allocate page according to address). This
1187 * could only happen if one pinned pte changed.
1188 */
1189 folio_put(prealloc);
1190 prealloc = NULL;
1191 }
1192 nr = ret;
1193 progress += 8 * nr;
1194 } while (dst_pte += nr, src_pte += nr, addr += PAGE_SIZE * nr,
1195 addr != end);
1196
1197 arch_leave_lazy_mmu_mode();
1198 pte_unmap_unlock(orig_src_pte, src_ptl);
1199 add_mm_rss_vec(dst_mm, rss);
1200 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1201 cond_resched();
1202
1203 if (ret == -EIO) {
1204 VM_WARN_ON_ONCE(!entry.val);
1205 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1206 ret = -ENOMEM;
1207 goto out;
1208 }
1209 entry.val = 0;
1210 } else if (ret == -EBUSY || unlikely(ret == -EHWPOISON)) {
1211 goto out;
1212 } else if (ret == -EAGAIN) {
1213 prealloc = folio_prealloc(src_mm, src_vma, addr, false);
1214 if (!prealloc)
1215 return -ENOMEM;
1216 } else if (ret < 0) {
1217 VM_WARN_ON_ONCE(1);
1218 }
1219
1220 /* We've captured and resolved the error. Reset, try again. */
1221 ret = 0;
1222
1223 if (addr != end)
1224 goto again;
1225out:
1226 if (unlikely(prealloc))
1227 folio_put(prealloc);
1228 return ret;
1229}
1230
1231static inline int
1232copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1233 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1234 unsigned long end)
1235{
1236 struct mm_struct *dst_mm = dst_vma->vm_mm;
1237 struct mm_struct *src_mm = src_vma->vm_mm;
1238 pmd_t *src_pmd, *dst_pmd;
1239 unsigned long next;
1240
1241 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1242 if (!dst_pmd)
1243 return -ENOMEM;
1244 src_pmd = pmd_offset(src_pud, addr);
1245 do {
1246 next = pmd_addr_end(addr, end);
1247 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1248 || pmd_devmap(*src_pmd)) {
1249 int err;
1250 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1251 err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1252 addr, dst_vma, src_vma);
1253 if (err == -ENOMEM)
1254 return -ENOMEM;
1255 if (!err)
1256 continue;
1257 /* fall through */
1258 }
1259 if (pmd_none_or_clear_bad(src_pmd))
1260 continue;
1261 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1262 addr, next))
1263 return -ENOMEM;
1264 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1265 return 0;
1266}
1267
1268static inline int
1269copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1270 p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1271 unsigned long end)
1272{
1273 struct mm_struct *dst_mm = dst_vma->vm_mm;
1274 struct mm_struct *src_mm = src_vma->vm_mm;
1275 pud_t *src_pud, *dst_pud;
1276 unsigned long next;
1277
1278 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1279 if (!dst_pud)
1280 return -ENOMEM;
1281 src_pud = pud_offset(src_p4d, addr);
1282 do {
1283 next = pud_addr_end(addr, end);
1284 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1285 int err;
1286
1287 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1288 err = copy_huge_pud(dst_mm, src_mm,
1289 dst_pud, src_pud, addr, src_vma);
1290 if (err == -ENOMEM)
1291 return -ENOMEM;
1292 if (!err)
1293 continue;
1294 /* fall through */
1295 }
1296 if (pud_none_or_clear_bad(src_pud))
1297 continue;
1298 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1299 addr, next))
1300 return -ENOMEM;
1301 } while (dst_pud++, src_pud++, addr = next, addr != end);
1302 return 0;
1303}
1304
1305static inline int
1306copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1307 pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1308 unsigned long end)
1309{
1310 struct mm_struct *dst_mm = dst_vma->vm_mm;
1311 p4d_t *src_p4d, *dst_p4d;
1312 unsigned long next;
1313
1314 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1315 if (!dst_p4d)
1316 return -ENOMEM;
1317 src_p4d = p4d_offset(src_pgd, addr);
1318 do {
1319 next = p4d_addr_end(addr, end);
1320 if (p4d_none_or_clear_bad(src_p4d))
1321 continue;
1322 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1323 addr, next))
1324 return -ENOMEM;
1325 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1326 return 0;
1327}
1328
1329/*
1330 * Return true if the vma needs to copy the pgtable during this fork(). Return
1331 * false when we can speed up fork() by allowing lazy page faults later until
1332 * when the child accesses the memory range.
1333 */
1334static bool
1335vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1336{
1337 /*
1338 * Always copy pgtables when dst_vma has uffd-wp enabled even if it's
1339 * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable
1340 * contains uffd-wp protection information, that's something we can't
1341 * retrieve from page cache, and skip copying will lose those info.
1342 */
1343 if (userfaultfd_wp(dst_vma))
1344 return true;
1345
1346 if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
1347 return true;
1348
1349 if (src_vma->anon_vma)
1350 return true;
1351
1352 /*
1353 * Don't copy ptes where a page fault will fill them correctly. Fork
1354 * becomes much lighter when there are big shared or private readonly
1355 * mappings. The tradeoff is that copy_page_range is more efficient
1356 * than faulting.
1357 */
1358 return false;
1359}
1360
1361int
1362copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1363{
1364 pgd_t *src_pgd, *dst_pgd;
1365 unsigned long next;
1366 unsigned long addr = src_vma->vm_start;
1367 unsigned long end = src_vma->vm_end;
1368 struct mm_struct *dst_mm = dst_vma->vm_mm;
1369 struct mm_struct *src_mm = src_vma->vm_mm;
1370 struct mmu_notifier_range range;
1371 bool is_cow;
1372 int ret;
1373
1374 if (!vma_needs_copy(dst_vma, src_vma))
1375 return 0;
1376
1377 if (is_vm_hugetlb_page(src_vma))
1378 return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma);
1379
1380 if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1381 /*
1382 * We do not free on error cases below as remove_vma
1383 * gets called on error from higher level routine
1384 */
1385 ret = track_pfn_copy(src_vma);
1386 if (ret)
1387 return ret;
1388 }
1389
1390 /*
1391 * We need to invalidate the secondary MMU mappings only when
1392 * there could be a permission downgrade on the ptes of the
1393 * parent mm. And a permission downgrade will only happen if
1394 * is_cow_mapping() returns true.
1395 */
1396 is_cow = is_cow_mapping(src_vma->vm_flags);
1397
1398 if (is_cow) {
1399 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1400 0, src_mm, addr, end);
1401 mmu_notifier_invalidate_range_start(&range);
1402 /*
1403 * Disabling preemption is not needed for the write side, as
1404 * the read side doesn't spin, but goes to the mmap_lock.
1405 *
1406 * Use the raw variant of the seqcount_t write API to avoid
1407 * lockdep complaining about preemptibility.
1408 */
1409 vma_assert_write_locked(src_vma);
1410 raw_write_seqcount_begin(&src_mm->write_protect_seq);
1411 }
1412
1413 ret = 0;
1414 dst_pgd = pgd_offset(dst_mm, addr);
1415 src_pgd = pgd_offset(src_mm, addr);
1416 do {
1417 next = pgd_addr_end(addr, end);
1418 if (pgd_none_or_clear_bad(src_pgd))
1419 continue;
1420 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1421 addr, next))) {
1422 untrack_pfn_clear(dst_vma);
1423 ret = -ENOMEM;
1424 break;
1425 }
1426 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1427
1428 if (is_cow) {
1429 raw_write_seqcount_end(&src_mm->write_protect_seq);
1430 mmu_notifier_invalidate_range_end(&range);
1431 }
1432 return ret;
1433}
1434
1435/* Whether we should zap all COWed (private) pages too */
1436static inline bool should_zap_cows(struct zap_details *details)
1437{
1438 /* By default, zap all pages */
1439 if (!details)
1440 return true;
1441
1442 /* Or, we zap COWed pages only if the caller wants to */
1443 return details->even_cows;
1444}
1445
1446/* Decides whether we should zap this folio with the folio pointer specified */
1447static inline bool should_zap_folio(struct zap_details *details,
1448 struct folio *folio)
1449{
1450 /* If we can make a decision without *folio.. */
1451 if (should_zap_cows(details))
1452 return true;
1453
1454 /* Otherwise we should only zap non-anon folios */
1455 return !folio_test_anon(folio);
1456}
1457
1458static inline bool zap_drop_markers(struct zap_details *details)
1459{
1460 if (!details)
1461 return false;
1462
1463 return details->zap_flags & ZAP_FLAG_DROP_MARKER;
1464}
1465
1466/*
1467 * This function makes sure that we'll replace the none pte with an uffd-wp
1468 * swap special pte marker when necessary. Must be with the pgtable lock held.
1469 */
1470static inline void
1471zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
1472 unsigned long addr, pte_t *pte, int nr,
1473 struct zap_details *details, pte_t pteval)
1474{
1475 /* Zap on anonymous always means dropping everything */
1476 if (vma_is_anonymous(vma))
1477 return;
1478
1479 if (zap_drop_markers(details))
1480 return;
1481
1482 for (;;) {
1483 /* the PFN in the PTE is irrelevant. */
1484 pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
1485 if (--nr == 0)
1486 break;
1487 pte++;
1488 addr += PAGE_SIZE;
1489 }
1490}
1491
1492static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb,
1493 struct vm_area_struct *vma, struct folio *folio,
1494 struct page *page, pte_t *pte, pte_t ptent, unsigned int nr,
1495 unsigned long addr, struct zap_details *details, int *rss,
1496 bool *force_flush, bool *force_break)
1497{
1498 struct mm_struct *mm = tlb->mm;
1499 bool delay_rmap = false;
1500
1501 if (!folio_test_anon(folio)) {
1502 ptent = get_and_clear_full_ptes(mm, addr, pte, nr, tlb->fullmm);
1503 if (pte_dirty(ptent)) {
1504 folio_mark_dirty(folio);
1505 if (tlb_delay_rmap(tlb)) {
1506 delay_rmap = true;
1507 *force_flush = true;
1508 }
1509 }
1510 if (pte_young(ptent) && likely(vma_has_recency(vma)))
1511 folio_mark_accessed(folio);
1512 rss[mm_counter(folio)] -= nr;
1513 } else {
1514 /* We don't need up-to-date accessed/dirty bits. */
1515 clear_full_ptes(mm, addr, pte, nr, tlb->fullmm);
1516 rss[MM_ANONPAGES] -= nr;
1517 }
1518 /* Checking a single PTE in a batch is sufficient. */
1519 arch_check_zapped_pte(vma, ptent);
1520 tlb_remove_tlb_entries(tlb, pte, nr, addr);
1521 if (unlikely(userfaultfd_pte_wp(vma, ptent)))
1522 zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details,
1523 ptent);
1524
1525 if (!delay_rmap) {
1526 folio_remove_rmap_ptes(folio, page, nr, vma);
1527
1528 if (unlikely(folio_mapcount(folio) < 0))
1529 print_bad_pte(vma, addr, ptent, page);
1530 }
1531 if (unlikely(__tlb_remove_folio_pages(tlb, page, nr, delay_rmap))) {
1532 *force_flush = true;
1533 *force_break = true;
1534 }
1535}
1536
1537/*
1538 * Zap or skip at least one present PTE, trying to batch-process subsequent
1539 * PTEs that map consecutive pages of the same folio.
1540 *
1541 * Returns the number of processed (skipped or zapped) PTEs (at least 1).
1542 */
1543static inline int zap_present_ptes(struct mmu_gather *tlb,
1544 struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
1545 unsigned int max_nr, unsigned long addr,
1546 struct zap_details *details, int *rss, bool *force_flush,
1547 bool *force_break)
1548{
1549 const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
1550 struct mm_struct *mm = tlb->mm;
1551 struct folio *folio;
1552 struct page *page;
1553 int nr;
1554
1555 page = vm_normal_page(vma, addr, ptent);
1556 if (!page) {
1557 /* We don't need up-to-date accessed/dirty bits. */
1558 ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
1559 arch_check_zapped_pte(vma, ptent);
1560 tlb_remove_tlb_entry(tlb, pte, addr);
1561 if (userfaultfd_pte_wp(vma, ptent))
1562 zap_install_uffd_wp_if_needed(vma, addr, pte, 1,
1563 details, ptent);
1564 ksm_might_unmap_zero_page(mm, ptent);
1565 return 1;
1566 }
1567
1568 folio = page_folio(page);
1569 if (unlikely(!should_zap_folio(details, folio)))
1570 return 1;
1571
1572 /*
1573 * Make sure that the common "small folio" case is as fast as possible
1574 * by keeping the batching logic separate.
1575 */
1576 if (unlikely(folio_test_large(folio) && max_nr != 1)) {
1577 nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, fpb_flags,
1578 NULL, NULL, NULL);
1579
1580 zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, nr,
1581 addr, details, rss, force_flush,
1582 force_break);
1583 return nr;
1584 }
1585 zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, 1, addr,
1586 details, rss, force_flush, force_break);
1587 return 1;
1588}
1589
1590static unsigned long zap_pte_range(struct mmu_gather *tlb,
1591 struct vm_area_struct *vma, pmd_t *pmd,
1592 unsigned long addr, unsigned long end,
1593 struct zap_details *details)
1594{
1595 bool force_flush = false, force_break = false;
1596 struct mm_struct *mm = tlb->mm;
1597 int rss[NR_MM_COUNTERS];
1598 spinlock_t *ptl;
1599 pte_t *start_pte;
1600 pte_t *pte;
1601 swp_entry_t entry;
1602 int nr;
1603
1604 tlb_change_page_size(tlb, PAGE_SIZE);
1605 init_rss_vec(rss);
1606 start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1607 if (!pte)
1608 return addr;
1609
1610 flush_tlb_batched_pending(mm);
1611 arch_enter_lazy_mmu_mode();
1612 do {
1613 pte_t ptent = ptep_get(pte);
1614 struct folio *folio;
1615 struct page *page;
1616 int max_nr;
1617
1618 nr = 1;
1619 if (pte_none(ptent))
1620 continue;
1621
1622 if (need_resched())
1623 break;
1624
1625 if (pte_present(ptent)) {
1626 max_nr = (end - addr) / PAGE_SIZE;
1627 nr = zap_present_ptes(tlb, vma, pte, ptent, max_nr,
1628 addr, details, rss, &force_flush,
1629 &force_break);
1630 if (unlikely(force_break)) {
1631 addr += nr * PAGE_SIZE;
1632 break;
1633 }
1634 continue;
1635 }
1636
1637 entry = pte_to_swp_entry(ptent);
1638 if (is_device_private_entry(entry) ||
1639 is_device_exclusive_entry(entry)) {
1640 page = pfn_swap_entry_to_page(entry);
1641 folio = page_folio(page);
1642 if (unlikely(!should_zap_folio(details, folio)))
1643 continue;
1644 /*
1645 * Both device private/exclusive mappings should only
1646 * work with anonymous page so far, so we don't need to
1647 * consider uffd-wp bit when zap. For more information,
1648 * see zap_install_uffd_wp_if_needed().
1649 */
1650 WARN_ON_ONCE(!vma_is_anonymous(vma));
1651 rss[mm_counter(folio)]--;
1652 if (is_device_private_entry(entry))
1653 folio_remove_rmap_pte(folio, page, vma);
1654 folio_put(folio);
1655 } else if (!non_swap_entry(entry)) {
1656 max_nr = (end - addr) / PAGE_SIZE;
1657 nr = swap_pte_batch(pte, max_nr, ptent);
1658 /* Genuine swap entries, hence a private anon pages */
1659 if (!should_zap_cows(details))
1660 continue;
1661 rss[MM_SWAPENTS] -= nr;
1662 free_swap_and_cache_nr(entry, nr);
1663 } else if (is_migration_entry(entry)) {
1664 folio = pfn_swap_entry_folio(entry);
1665 if (!should_zap_folio(details, folio))
1666 continue;
1667 rss[mm_counter(folio)]--;
1668 } else if (pte_marker_entry_uffd_wp(entry)) {
1669 /*
1670 * For anon: always drop the marker; for file: only
1671 * drop the marker if explicitly requested.
1672 */
1673 if (!vma_is_anonymous(vma) &&
1674 !zap_drop_markers(details))
1675 continue;
1676 } else if (is_guard_swp_entry(entry)) {
1677 /*
1678 * Ordinary zapping should not remove guard PTE
1679 * markers. Only do so if we should remove PTE markers
1680 * in general.
1681 */
1682 if (!zap_drop_markers(details))
1683 continue;
1684 } else if (is_hwpoison_entry(entry) ||
1685 is_poisoned_swp_entry(entry)) {
1686 if (!should_zap_cows(details))
1687 continue;
1688 } else {
1689 /* We should have covered all the swap entry types */
1690 pr_alert("unrecognized swap entry 0x%lx\n", entry.val);
1691 WARN_ON_ONCE(1);
1692 }
1693 clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm);
1694 zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent);
1695 } while (pte += nr, addr += PAGE_SIZE * nr, addr != end);
1696
1697 add_mm_rss_vec(mm, rss);
1698 arch_leave_lazy_mmu_mode();
1699
1700 /* Do the actual TLB flush before dropping ptl */
1701 if (force_flush) {
1702 tlb_flush_mmu_tlbonly(tlb);
1703 tlb_flush_rmaps(tlb, vma);
1704 }
1705 pte_unmap_unlock(start_pte, ptl);
1706
1707 /*
1708 * If we forced a TLB flush (either due to running out of
1709 * batch buffers or because we needed to flush dirty TLB
1710 * entries before releasing the ptl), free the batched
1711 * memory too. Come back again if we didn't do everything.
1712 */
1713 if (force_flush)
1714 tlb_flush_mmu(tlb);
1715
1716 return addr;
1717}
1718
1719static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1720 struct vm_area_struct *vma, pud_t *pud,
1721 unsigned long addr, unsigned long end,
1722 struct zap_details *details)
1723{
1724 pmd_t *pmd;
1725 unsigned long next;
1726
1727 pmd = pmd_offset(pud, addr);
1728 do {
1729 next = pmd_addr_end(addr, end);
1730 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1731 if (next - addr != HPAGE_PMD_SIZE)
1732 __split_huge_pmd(vma, pmd, addr, false, NULL);
1733 else if (zap_huge_pmd(tlb, vma, pmd, addr)) {
1734 addr = next;
1735 continue;
1736 }
1737 /* fall through */
1738 } else if (details && details->single_folio &&
1739 folio_test_pmd_mappable(details->single_folio) &&
1740 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1741 spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1742 /*
1743 * Take and drop THP pmd lock so that we cannot return
1744 * prematurely, while zap_huge_pmd() has cleared *pmd,
1745 * but not yet decremented compound_mapcount().
1746 */
1747 spin_unlock(ptl);
1748 }
1749 if (pmd_none(*pmd)) {
1750 addr = next;
1751 continue;
1752 }
1753 addr = zap_pte_range(tlb, vma, pmd, addr, next, details);
1754 if (addr != next)
1755 pmd--;
1756 } while (pmd++, cond_resched(), addr != end);
1757
1758 return addr;
1759}
1760
1761static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1762 struct vm_area_struct *vma, p4d_t *p4d,
1763 unsigned long addr, unsigned long end,
1764 struct zap_details *details)
1765{
1766 pud_t *pud;
1767 unsigned long next;
1768
1769 pud = pud_offset(p4d, addr);
1770 do {
1771 next = pud_addr_end(addr, end);
1772 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1773 if (next - addr != HPAGE_PUD_SIZE) {
1774 mmap_assert_locked(tlb->mm);
1775 split_huge_pud(vma, pud, addr);
1776 } else if (zap_huge_pud(tlb, vma, pud, addr))
1777 goto next;
1778 /* fall through */
1779 }
1780 if (pud_none_or_clear_bad(pud))
1781 continue;
1782 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1783next:
1784 cond_resched();
1785 } while (pud++, addr = next, addr != end);
1786
1787 return addr;
1788}
1789
1790static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1791 struct vm_area_struct *vma, pgd_t *pgd,
1792 unsigned long addr, unsigned long end,
1793 struct zap_details *details)
1794{
1795 p4d_t *p4d;
1796 unsigned long next;
1797
1798 p4d = p4d_offset(pgd, addr);
1799 do {
1800 next = p4d_addr_end(addr, end);
1801 if (p4d_none_or_clear_bad(p4d))
1802 continue;
1803 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1804 } while (p4d++, addr = next, addr != end);
1805
1806 return addr;
1807}
1808
1809void unmap_page_range(struct mmu_gather *tlb,
1810 struct vm_area_struct *vma,
1811 unsigned long addr, unsigned long end,
1812 struct zap_details *details)
1813{
1814 pgd_t *pgd;
1815 unsigned long next;
1816
1817 BUG_ON(addr >= end);
1818 tlb_start_vma(tlb, vma);
1819 pgd = pgd_offset(vma->vm_mm, addr);
1820 do {
1821 next = pgd_addr_end(addr, end);
1822 if (pgd_none_or_clear_bad(pgd))
1823 continue;
1824 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1825 } while (pgd++, addr = next, addr != end);
1826 tlb_end_vma(tlb, vma);
1827}
1828
1829
1830static void unmap_single_vma(struct mmu_gather *tlb,
1831 struct vm_area_struct *vma, unsigned long start_addr,
1832 unsigned long end_addr,
1833 struct zap_details *details, bool mm_wr_locked)
1834{
1835 unsigned long start = max(vma->vm_start, start_addr);
1836 unsigned long end;
1837
1838 if (start >= vma->vm_end)
1839 return;
1840 end = min(vma->vm_end, end_addr);
1841 if (end <= vma->vm_start)
1842 return;
1843
1844 if (vma->vm_file)
1845 uprobe_munmap(vma, start, end);
1846
1847 if (unlikely(vma->vm_flags & VM_PFNMAP))
1848 untrack_pfn(vma, 0, 0, mm_wr_locked);
1849
1850 if (start != end) {
1851 if (unlikely(is_vm_hugetlb_page(vma))) {
1852 /*
1853 * It is undesirable to test vma->vm_file as it
1854 * should be non-null for valid hugetlb area.
1855 * However, vm_file will be NULL in the error
1856 * cleanup path of mmap_region. When
1857 * hugetlbfs ->mmap method fails,
1858 * mmap_region() nullifies vma->vm_file
1859 * before calling this function to clean up.
1860 * Since no pte has actually been setup, it is
1861 * safe to do nothing in this case.
1862 */
1863 if (vma->vm_file) {
1864 zap_flags_t zap_flags = details ?
1865 details->zap_flags : 0;
1866 __unmap_hugepage_range(tlb, vma, start, end,
1867 NULL, zap_flags);
1868 }
1869 } else
1870 unmap_page_range(tlb, vma, start, end, details);
1871 }
1872}
1873
1874/**
1875 * unmap_vmas - unmap a range of memory covered by a list of vma's
1876 * @tlb: address of the caller's struct mmu_gather
1877 * @mas: the maple state
1878 * @vma: the starting vma
1879 * @start_addr: virtual address at which to start unmapping
1880 * @end_addr: virtual address at which to end unmapping
1881 * @tree_end: The maximum index to check
1882 * @mm_wr_locked: lock flag
1883 *
1884 * Unmap all pages in the vma list.
1885 *
1886 * Only addresses between `start' and `end' will be unmapped.
1887 *
1888 * The VMA list must be sorted in ascending virtual address order.
1889 *
1890 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1891 * range after unmap_vmas() returns. So the only responsibility here is to
1892 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1893 * drops the lock and schedules.
1894 */
1895void unmap_vmas(struct mmu_gather *tlb, struct ma_state *mas,
1896 struct vm_area_struct *vma, unsigned long start_addr,
1897 unsigned long end_addr, unsigned long tree_end,
1898 bool mm_wr_locked)
1899{
1900 struct mmu_notifier_range range;
1901 struct zap_details details = {
1902 .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP,
1903 /* Careful - we need to zap private pages too! */
1904 .even_cows = true,
1905 };
1906
1907 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm,
1908 start_addr, end_addr);
1909 mmu_notifier_invalidate_range_start(&range);
1910 do {
1911 unsigned long start = start_addr;
1912 unsigned long end = end_addr;
1913 hugetlb_zap_begin(vma, &start, &end);
1914 unmap_single_vma(tlb, vma, start, end, &details,
1915 mm_wr_locked);
1916 hugetlb_zap_end(vma, &details);
1917 vma = mas_find(mas, tree_end - 1);
1918 } while (vma && likely(!xa_is_zero(vma)));
1919 mmu_notifier_invalidate_range_end(&range);
1920}
1921
1922/**
1923 * zap_page_range_single - remove user pages in a given range
1924 * @vma: vm_area_struct holding the applicable pages
1925 * @address: starting address of pages to zap
1926 * @size: number of bytes to zap
1927 * @details: details of shared cache invalidation
1928 *
1929 * The range must fit into one VMA.
1930 */
1931void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1932 unsigned long size, struct zap_details *details)
1933{
1934 const unsigned long end = address + size;
1935 struct mmu_notifier_range range;
1936 struct mmu_gather tlb;
1937
1938 lru_add_drain();
1939 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
1940 address, end);
1941 hugetlb_zap_begin(vma, &range.start, &range.end);
1942 tlb_gather_mmu(&tlb, vma->vm_mm);
1943 update_hiwater_rss(vma->vm_mm);
1944 mmu_notifier_invalidate_range_start(&range);
1945 /*
1946 * unmap 'address-end' not 'range.start-range.end' as range
1947 * could have been expanded for hugetlb pmd sharing.
1948 */
1949 unmap_single_vma(&tlb, vma, address, end, details, false);
1950 mmu_notifier_invalidate_range_end(&range);
1951 tlb_finish_mmu(&tlb);
1952 hugetlb_zap_end(vma, details);
1953}
1954
1955/**
1956 * zap_vma_ptes - remove ptes mapping the vma
1957 * @vma: vm_area_struct holding ptes to be zapped
1958 * @address: starting address of pages to zap
1959 * @size: number of bytes to zap
1960 *
1961 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1962 *
1963 * The entire address range must be fully contained within the vma.
1964 *
1965 */
1966void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1967 unsigned long size)
1968{
1969 if (!range_in_vma(vma, address, address + size) ||
1970 !(vma->vm_flags & VM_PFNMAP))
1971 return;
1972
1973 zap_page_range_single(vma, address, size, NULL);
1974}
1975EXPORT_SYMBOL_GPL(zap_vma_ptes);
1976
1977static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1978{
1979 pgd_t *pgd;
1980 p4d_t *p4d;
1981 pud_t *pud;
1982 pmd_t *pmd;
1983
1984 pgd = pgd_offset(mm, addr);
1985 p4d = p4d_alloc(mm, pgd, addr);
1986 if (!p4d)
1987 return NULL;
1988 pud = pud_alloc(mm, p4d, addr);
1989 if (!pud)
1990 return NULL;
1991 pmd = pmd_alloc(mm, pud, addr);
1992 if (!pmd)
1993 return NULL;
1994
1995 VM_BUG_ON(pmd_trans_huge(*pmd));
1996 return pmd;
1997}
1998
1999pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
2000 spinlock_t **ptl)
2001{
2002 pmd_t *pmd = walk_to_pmd(mm, addr);
2003
2004 if (!pmd)
2005 return NULL;
2006 return pte_alloc_map_lock(mm, pmd, addr, ptl);
2007}
2008
2009static bool vm_mixed_zeropage_allowed(struct vm_area_struct *vma)
2010{
2011 VM_WARN_ON_ONCE(vma->vm_flags & VM_PFNMAP);
2012 /*
2013 * Whoever wants to forbid the zeropage after some zeropages
2014 * might already have been mapped has to scan the page tables and
2015 * bail out on any zeropages. Zeropages in COW mappings can
2016 * be unshared using FAULT_FLAG_UNSHARE faults.
2017 */
2018 if (mm_forbids_zeropage(vma->vm_mm))
2019 return false;
2020 /* zeropages in COW mappings are common and unproblematic. */
2021 if (is_cow_mapping(vma->vm_flags))
2022 return true;
2023 /* Mappings that do not allow for writable PTEs are unproblematic. */
2024 if (!(vma->vm_flags & (VM_WRITE | VM_MAYWRITE)))
2025 return true;
2026 /*
2027 * Why not allow any VMA that has vm_ops->pfn_mkwrite? GUP could
2028 * find the shared zeropage and longterm-pin it, which would
2029 * be problematic as soon as the zeropage gets replaced by a different
2030 * page due to vma->vm_ops->pfn_mkwrite, because what's mapped would
2031 * now differ to what GUP looked up. FSDAX is incompatible to
2032 * FOLL_LONGTERM and VM_IO is incompatible to GUP completely (see
2033 * check_vma_flags).
2034 */
2035 return vma->vm_ops && vma->vm_ops->pfn_mkwrite &&
2036 (vma_is_fsdax(vma) || vma->vm_flags & VM_IO);
2037}
2038
2039static int validate_page_before_insert(struct vm_area_struct *vma,
2040 struct page *page)
2041{
2042 struct folio *folio = page_folio(page);
2043
2044 if (!folio_ref_count(folio))
2045 return -EINVAL;
2046 if (unlikely(is_zero_folio(folio))) {
2047 if (!vm_mixed_zeropage_allowed(vma))
2048 return -EINVAL;
2049 return 0;
2050 }
2051 if (folio_test_anon(folio) || folio_test_slab(folio) ||
2052 page_has_type(page))
2053 return -EINVAL;
2054 flush_dcache_folio(folio);
2055 return 0;
2056}
2057
2058static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
2059 unsigned long addr, struct page *page, pgprot_t prot)
2060{
2061 struct folio *folio = page_folio(page);
2062 pte_t pteval;
2063
2064 if (!pte_none(ptep_get(pte)))
2065 return -EBUSY;
2066 /* Ok, finally just insert the thing.. */
2067 pteval = mk_pte(page, prot);
2068 if (unlikely(is_zero_folio(folio))) {
2069 pteval = pte_mkspecial(pteval);
2070 } else {
2071 folio_get(folio);
2072 inc_mm_counter(vma->vm_mm, mm_counter_file(folio));
2073 folio_add_file_rmap_pte(folio, page, vma);
2074 }
2075 set_pte_at(vma->vm_mm, addr, pte, pteval);
2076 return 0;
2077}
2078
2079static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2080 struct page *page, pgprot_t prot)
2081{
2082 int retval;
2083 pte_t *pte;
2084 spinlock_t *ptl;
2085
2086 retval = validate_page_before_insert(vma, page);
2087 if (retval)
2088 goto out;
2089 retval = -ENOMEM;
2090 pte = get_locked_pte(vma->vm_mm, addr, &ptl);
2091 if (!pte)
2092 goto out;
2093 retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
2094 pte_unmap_unlock(pte, ptl);
2095out:
2096 return retval;
2097}
2098
2099static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
2100 unsigned long addr, struct page *page, pgprot_t prot)
2101{
2102 int err;
2103
2104 err = validate_page_before_insert(vma, page);
2105 if (err)
2106 return err;
2107 return insert_page_into_pte_locked(vma, pte, addr, page, prot);
2108}
2109
2110/* insert_pages() amortizes the cost of spinlock operations
2111 * when inserting pages in a loop.
2112 */
2113static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
2114 struct page **pages, unsigned long *num, pgprot_t prot)
2115{
2116 pmd_t *pmd = NULL;
2117 pte_t *start_pte, *pte;
2118 spinlock_t *pte_lock;
2119 struct mm_struct *const mm = vma->vm_mm;
2120 unsigned long curr_page_idx = 0;
2121 unsigned long remaining_pages_total = *num;
2122 unsigned long pages_to_write_in_pmd;
2123 int ret;
2124more:
2125 ret = -EFAULT;
2126 pmd = walk_to_pmd(mm, addr);
2127 if (!pmd)
2128 goto out;
2129
2130 pages_to_write_in_pmd = min_t(unsigned long,
2131 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
2132
2133 /* Allocate the PTE if necessary; takes PMD lock once only. */
2134 ret = -ENOMEM;
2135 if (pte_alloc(mm, pmd))
2136 goto out;
2137
2138 while (pages_to_write_in_pmd) {
2139 int pte_idx = 0;
2140 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
2141
2142 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
2143 if (!start_pte) {
2144 ret = -EFAULT;
2145 goto out;
2146 }
2147 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
2148 int err = insert_page_in_batch_locked(vma, pte,
2149 addr, pages[curr_page_idx], prot);
2150 if (unlikely(err)) {
2151 pte_unmap_unlock(start_pte, pte_lock);
2152 ret = err;
2153 remaining_pages_total -= pte_idx;
2154 goto out;
2155 }
2156 addr += PAGE_SIZE;
2157 ++curr_page_idx;
2158 }
2159 pte_unmap_unlock(start_pte, pte_lock);
2160 pages_to_write_in_pmd -= batch_size;
2161 remaining_pages_total -= batch_size;
2162 }
2163 if (remaining_pages_total)
2164 goto more;
2165 ret = 0;
2166out:
2167 *num = remaining_pages_total;
2168 return ret;
2169}
2170
2171/**
2172 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
2173 * @vma: user vma to map to
2174 * @addr: target start user address of these pages
2175 * @pages: source kernel pages
2176 * @num: in: number of pages to map. out: number of pages that were *not*
2177 * mapped. (0 means all pages were successfully mapped).
2178 *
2179 * Preferred over vm_insert_page() when inserting multiple pages.
2180 *
2181 * In case of error, we may have mapped a subset of the provided
2182 * pages. It is the caller's responsibility to account for this case.
2183 *
2184 * The same restrictions apply as in vm_insert_page().
2185 */
2186int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
2187 struct page **pages, unsigned long *num)
2188{
2189 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
2190
2191 if (addr < vma->vm_start || end_addr >= vma->vm_end)
2192 return -EFAULT;
2193 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2194 BUG_ON(mmap_read_trylock(vma->vm_mm));
2195 BUG_ON(vma->vm_flags & VM_PFNMAP);
2196 vm_flags_set(vma, VM_MIXEDMAP);
2197 }
2198 /* Defer page refcount checking till we're about to map that page. */
2199 return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
2200}
2201EXPORT_SYMBOL(vm_insert_pages);
2202
2203/**
2204 * vm_insert_page - insert single page into user vma
2205 * @vma: user vma to map to
2206 * @addr: target user address of this page
2207 * @page: source kernel page
2208 *
2209 * This allows drivers to insert individual pages they've allocated
2210 * into a user vma. The zeropage is supported in some VMAs,
2211 * see vm_mixed_zeropage_allowed().
2212 *
2213 * The page has to be a nice clean _individual_ kernel allocation.
2214 * If you allocate a compound page, you need to have marked it as
2215 * such (__GFP_COMP), or manually just split the page up yourself
2216 * (see split_page()).
2217 *
2218 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2219 * took an arbitrary page protection parameter. This doesn't allow
2220 * that. Your vma protection will have to be set up correctly, which
2221 * means that if you want a shared writable mapping, you'd better
2222 * ask for a shared writable mapping!
2223 *
2224 * The page does not need to be reserved.
2225 *
2226 * Usually this function is called from f_op->mmap() handler
2227 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
2228 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2229 * function from other places, for example from page-fault handler.
2230 *
2231 * Return: %0 on success, negative error code otherwise.
2232 */
2233int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2234 struct page *page)
2235{
2236 if (addr < vma->vm_start || addr >= vma->vm_end)
2237 return -EFAULT;
2238 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2239 BUG_ON(mmap_read_trylock(vma->vm_mm));
2240 BUG_ON(vma->vm_flags & VM_PFNMAP);
2241 vm_flags_set(vma, VM_MIXEDMAP);
2242 }
2243 return insert_page(vma, addr, page, vma->vm_page_prot);
2244}
2245EXPORT_SYMBOL(vm_insert_page);
2246
2247/*
2248 * __vm_map_pages - maps range of kernel pages into user vma
2249 * @vma: user vma to map to
2250 * @pages: pointer to array of source kernel pages
2251 * @num: number of pages in page array
2252 * @offset: user's requested vm_pgoff
2253 *
2254 * This allows drivers to map range of kernel pages into a user vma.
2255 * The zeropage is supported in some VMAs, see
2256 * vm_mixed_zeropage_allowed().
2257 *
2258 * Return: 0 on success and error code otherwise.
2259 */
2260static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2261 unsigned long num, unsigned long offset)
2262{
2263 unsigned long count = vma_pages(vma);
2264 unsigned long uaddr = vma->vm_start;
2265 int ret, i;
2266
2267 /* Fail if the user requested offset is beyond the end of the object */
2268 if (offset >= num)
2269 return -ENXIO;
2270
2271 /* Fail if the user requested size exceeds available object size */
2272 if (count > num - offset)
2273 return -ENXIO;
2274
2275 for (i = 0; i < count; i++) {
2276 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
2277 if (ret < 0)
2278 return ret;
2279 uaddr += PAGE_SIZE;
2280 }
2281
2282 return 0;
2283}
2284
2285/**
2286 * vm_map_pages - maps range of kernel pages starts with non zero offset
2287 * @vma: user vma to map to
2288 * @pages: pointer to array of source kernel pages
2289 * @num: number of pages in page array
2290 *
2291 * Maps an object consisting of @num pages, catering for the user's
2292 * requested vm_pgoff
2293 *
2294 * If we fail to insert any page into the vma, the function will return
2295 * immediately leaving any previously inserted pages present. Callers
2296 * from the mmap handler may immediately return the error as their caller
2297 * will destroy the vma, removing any successfully inserted pages. Other
2298 * callers should make their own arrangements for calling unmap_region().
2299 *
2300 * Context: Process context. Called by mmap handlers.
2301 * Return: 0 on success and error code otherwise.
2302 */
2303int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2304 unsigned long num)
2305{
2306 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2307}
2308EXPORT_SYMBOL(vm_map_pages);
2309
2310/**
2311 * vm_map_pages_zero - map range of kernel pages starts with zero offset
2312 * @vma: user vma to map to
2313 * @pages: pointer to array of source kernel pages
2314 * @num: number of pages in page array
2315 *
2316 * Similar to vm_map_pages(), except that it explicitly sets the offset
2317 * to 0. This function is intended for the drivers that did not consider
2318 * vm_pgoff.
2319 *
2320 * Context: Process context. Called by mmap handlers.
2321 * Return: 0 on success and error code otherwise.
2322 */
2323int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2324 unsigned long num)
2325{
2326 return __vm_map_pages(vma, pages, num, 0);
2327}
2328EXPORT_SYMBOL(vm_map_pages_zero);
2329
2330static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2331 pfn_t pfn, pgprot_t prot, bool mkwrite)
2332{
2333 struct mm_struct *mm = vma->vm_mm;
2334 pte_t *pte, entry;
2335 spinlock_t *ptl;
2336
2337 pte = get_locked_pte(mm, addr, &ptl);
2338 if (!pte)
2339 return VM_FAULT_OOM;
2340 entry = ptep_get(pte);
2341 if (!pte_none(entry)) {
2342 if (mkwrite) {
2343 /*
2344 * For read faults on private mappings the PFN passed
2345 * in may not match the PFN we have mapped if the
2346 * mapped PFN is a writeable COW page. In the mkwrite
2347 * case we are creating a writable PTE for a shared
2348 * mapping and we expect the PFNs to match. If they
2349 * don't match, we are likely racing with block
2350 * allocation and mapping invalidation so just skip the
2351 * update.
2352 */
2353 if (pte_pfn(entry) != pfn_t_to_pfn(pfn)) {
2354 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry)));
2355 goto out_unlock;
2356 }
2357 entry = pte_mkyoung(entry);
2358 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2359 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2360 update_mmu_cache(vma, addr, pte);
2361 }
2362 goto out_unlock;
2363 }
2364
2365 /* Ok, finally just insert the thing.. */
2366 if (pfn_t_devmap(pfn))
2367 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2368 else
2369 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2370
2371 if (mkwrite) {
2372 entry = pte_mkyoung(entry);
2373 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2374 }
2375
2376 set_pte_at(mm, addr, pte, entry);
2377 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2378
2379out_unlock:
2380 pte_unmap_unlock(pte, ptl);
2381 return VM_FAULT_NOPAGE;
2382}
2383
2384/**
2385 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2386 * @vma: user vma to map to
2387 * @addr: target user address of this page
2388 * @pfn: source kernel pfn
2389 * @pgprot: pgprot flags for the inserted page
2390 *
2391 * This is exactly like vmf_insert_pfn(), except that it allows drivers
2392 * to override pgprot on a per-page basis.
2393 *
2394 * This only makes sense for IO mappings, and it makes no sense for
2395 * COW mappings. In general, using multiple vmas is preferable;
2396 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2397 * impractical.
2398 *
2399 * pgprot typically only differs from @vma->vm_page_prot when drivers set
2400 * caching- and encryption bits different than those of @vma->vm_page_prot,
2401 * because the caching- or encryption mode may not be known at mmap() time.
2402 *
2403 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2404 * to set caching and encryption bits for those vmas (except for COW pages).
2405 * This is ensured by core vm only modifying these page table entries using
2406 * functions that don't touch caching- or encryption bits, using pte_modify()
2407 * if needed. (See for example mprotect()).
2408 *
2409 * Also when new page-table entries are created, this is only done using the
2410 * fault() callback, and never using the value of vma->vm_page_prot,
2411 * except for page-table entries that point to anonymous pages as the result
2412 * of COW.
2413 *
2414 * Context: Process context. May allocate using %GFP_KERNEL.
2415 * Return: vm_fault_t value.
2416 */
2417vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2418 unsigned long pfn, pgprot_t pgprot)
2419{
2420 /*
2421 * Technically, architectures with pte_special can avoid all these
2422 * restrictions (same for remap_pfn_range). However we would like
2423 * consistency in testing and feature parity among all, so we should
2424 * try to keep these invariants in place for everybody.
2425 */
2426 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2427 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2428 (VM_PFNMAP|VM_MIXEDMAP));
2429 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2430 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2431
2432 if (addr < vma->vm_start || addr >= vma->vm_end)
2433 return VM_FAULT_SIGBUS;
2434
2435 if (!pfn_modify_allowed(pfn, pgprot))
2436 return VM_FAULT_SIGBUS;
2437
2438 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2439
2440 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2441 false);
2442}
2443EXPORT_SYMBOL(vmf_insert_pfn_prot);
2444
2445/**
2446 * vmf_insert_pfn - insert single pfn into user vma
2447 * @vma: user vma to map to
2448 * @addr: target user address of this page
2449 * @pfn: source kernel pfn
2450 *
2451 * Similar to vm_insert_page, this allows drivers to insert individual pages
2452 * they've allocated into a user vma. Same comments apply.
2453 *
2454 * This function should only be called from a vm_ops->fault handler, and
2455 * in that case the handler should return the result of this function.
2456 *
2457 * vma cannot be a COW mapping.
2458 *
2459 * As this is called only for pages that do not currently exist, we
2460 * do not need to flush old virtual caches or the TLB.
2461 *
2462 * Context: Process context. May allocate using %GFP_KERNEL.
2463 * Return: vm_fault_t value.
2464 */
2465vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2466 unsigned long pfn)
2467{
2468 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2469}
2470EXPORT_SYMBOL(vmf_insert_pfn);
2471
2472static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn, bool mkwrite)
2473{
2474 if (unlikely(is_zero_pfn(pfn_t_to_pfn(pfn))) &&
2475 (mkwrite || !vm_mixed_zeropage_allowed(vma)))
2476 return false;
2477 /* these checks mirror the abort conditions in vm_normal_page */
2478 if (vma->vm_flags & VM_MIXEDMAP)
2479 return true;
2480 if (pfn_t_devmap(pfn))
2481 return true;
2482 if (pfn_t_special(pfn))
2483 return true;
2484 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2485 return true;
2486 return false;
2487}
2488
2489static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2490 unsigned long addr, pfn_t pfn, bool mkwrite)
2491{
2492 pgprot_t pgprot = vma->vm_page_prot;
2493 int err;
2494
2495 if (!vm_mixed_ok(vma, pfn, mkwrite))
2496 return VM_FAULT_SIGBUS;
2497
2498 if (addr < vma->vm_start || addr >= vma->vm_end)
2499 return VM_FAULT_SIGBUS;
2500
2501 track_pfn_insert(vma, &pgprot, pfn);
2502
2503 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2504 return VM_FAULT_SIGBUS;
2505
2506 /*
2507 * If we don't have pte special, then we have to use the pfn_valid()
2508 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2509 * refcount the page if pfn_valid is true (hence insert_page rather
2510 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2511 * without pte special, it would there be refcounted as a normal page.
2512 */
2513 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2514 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2515 struct page *page;
2516
2517 /*
2518 * At this point we are committed to insert_page()
2519 * regardless of whether the caller specified flags that
2520 * result in pfn_t_has_page() == false.
2521 */
2522 page = pfn_to_page(pfn_t_to_pfn(pfn));
2523 err = insert_page(vma, addr, page, pgprot);
2524 } else {
2525 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2526 }
2527
2528 if (err == -ENOMEM)
2529 return VM_FAULT_OOM;
2530 if (err < 0 && err != -EBUSY)
2531 return VM_FAULT_SIGBUS;
2532
2533 return VM_FAULT_NOPAGE;
2534}
2535
2536vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2537 pfn_t pfn)
2538{
2539 return __vm_insert_mixed(vma, addr, pfn, false);
2540}
2541EXPORT_SYMBOL(vmf_insert_mixed);
2542
2543/*
2544 * If the insertion of PTE failed because someone else already added a
2545 * different entry in the mean time, we treat that as success as we assume
2546 * the same entry was actually inserted.
2547 */
2548vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2549 unsigned long addr, pfn_t pfn)
2550{
2551 return __vm_insert_mixed(vma, addr, pfn, true);
2552}
2553
2554/*
2555 * maps a range of physical memory into the requested pages. the old
2556 * mappings are removed. any references to nonexistent pages results
2557 * in null mappings (currently treated as "copy-on-access")
2558 */
2559static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2560 unsigned long addr, unsigned long end,
2561 unsigned long pfn, pgprot_t prot)
2562{
2563 pte_t *pte, *mapped_pte;
2564 spinlock_t *ptl;
2565 int err = 0;
2566
2567 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2568 if (!pte)
2569 return -ENOMEM;
2570 arch_enter_lazy_mmu_mode();
2571 do {
2572 BUG_ON(!pte_none(ptep_get(pte)));
2573 if (!pfn_modify_allowed(pfn, prot)) {
2574 err = -EACCES;
2575 break;
2576 }
2577 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2578 pfn++;
2579 } while (pte++, addr += PAGE_SIZE, addr != end);
2580 arch_leave_lazy_mmu_mode();
2581 pte_unmap_unlock(mapped_pte, ptl);
2582 return err;
2583}
2584
2585static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2586 unsigned long addr, unsigned long end,
2587 unsigned long pfn, pgprot_t prot)
2588{
2589 pmd_t *pmd;
2590 unsigned long next;
2591 int err;
2592
2593 pfn -= addr >> PAGE_SHIFT;
2594 pmd = pmd_alloc(mm, pud, addr);
2595 if (!pmd)
2596 return -ENOMEM;
2597 VM_BUG_ON(pmd_trans_huge(*pmd));
2598 do {
2599 next = pmd_addr_end(addr, end);
2600 err = remap_pte_range(mm, pmd, addr, next,
2601 pfn + (addr >> PAGE_SHIFT), prot);
2602 if (err)
2603 return err;
2604 } while (pmd++, addr = next, addr != end);
2605 return 0;
2606}
2607
2608static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2609 unsigned long addr, unsigned long end,
2610 unsigned long pfn, pgprot_t prot)
2611{
2612 pud_t *pud;
2613 unsigned long next;
2614 int err;
2615
2616 pfn -= addr >> PAGE_SHIFT;
2617 pud = pud_alloc(mm, p4d, addr);
2618 if (!pud)
2619 return -ENOMEM;
2620 do {
2621 next = pud_addr_end(addr, end);
2622 err = remap_pmd_range(mm, pud, addr, next,
2623 pfn + (addr >> PAGE_SHIFT), prot);
2624 if (err)
2625 return err;
2626 } while (pud++, addr = next, addr != end);
2627 return 0;
2628}
2629
2630static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2631 unsigned long addr, unsigned long end,
2632 unsigned long pfn, pgprot_t prot)
2633{
2634 p4d_t *p4d;
2635 unsigned long next;
2636 int err;
2637
2638 pfn -= addr >> PAGE_SHIFT;
2639 p4d = p4d_alloc(mm, pgd, addr);
2640 if (!p4d)
2641 return -ENOMEM;
2642 do {
2643 next = p4d_addr_end(addr, end);
2644 err = remap_pud_range(mm, p4d, addr, next,
2645 pfn + (addr >> PAGE_SHIFT), prot);
2646 if (err)
2647 return err;
2648 } while (p4d++, addr = next, addr != end);
2649 return 0;
2650}
2651
2652static int remap_pfn_range_internal(struct vm_area_struct *vma, unsigned long addr,
2653 unsigned long pfn, unsigned long size, pgprot_t prot)
2654{
2655 pgd_t *pgd;
2656 unsigned long next;
2657 unsigned long end = addr + PAGE_ALIGN(size);
2658 struct mm_struct *mm = vma->vm_mm;
2659 int err;
2660
2661 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2662 return -EINVAL;
2663
2664 /*
2665 * Physically remapped pages are special. Tell the
2666 * rest of the world about it:
2667 * VM_IO tells people not to look at these pages
2668 * (accesses can have side effects).
2669 * VM_PFNMAP tells the core MM that the base pages are just
2670 * raw PFN mappings, and do not have a "struct page" associated
2671 * with them.
2672 * VM_DONTEXPAND
2673 * Disable vma merging and expanding with mremap().
2674 * VM_DONTDUMP
2675 * Omit vma from core dump, even when VM_IO turned off.
2676 *
2677 * There's a horrible special case to handle copy-on-write
2678 * behaviour that some programs depend on. We mark the "original"
2679 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2680 * See vm_normal_page() for details.
2681 */
2682 if (is_cow_mapping(vma->vm_flags)) {
2683 if (addr != vma->vm_start || end != vma->vm_end)
2684 return -EINVAL;
2685 vma->vm_pgoff = pfn;
2686 }
2687
2688 vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
2689
2690 BUG_ON(addr >= end);
2691 pfn -= addr >> PAGE_SHIFT;
2692 pgd = pgd_offset(mm, addr);
2693 flush_cache_range(vma, addr, end);
2694 do {
2695 next = pgd_addr_end(addr, end);
2696 err = remap_p4d_range(mm, pgd, addr, next,
2697 pfn + (addr >> PAGE_SHIFT), prot);
2698 if (err)
2699 return err;
2700 } while (pgd++, addr = next, addr != end);
2701
2702 return 0;
2703}
2704
2705/*
2706 * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
2707 * must have pre-validated the caching bits of the pgprot_t.
2708 */
2709int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2710 unsigned long pfn, unsigned long size, pgprot_t prot)
2711{
2712 int error = remap_pfn_range_internal(vma, addr, pfn, size, prot);
2713
2714 if (!error)
2715 return 0;
2716
2717 /*
2718 * A partial pfn range mapping is dangerous: it does not
2719 * maintain page reference counts, and callers may free
2720 * pages due to the error. So zap it early.
2721 */
2722 zap_page_range_single(vma, addr, size, NULL);
2723 return error;
2724}
2725
2726/**
2727 * remap_pfn_range - remap kernel memory to userspace
2728 * @vma: user vma to map to
2729 * @addr: target page aligned user address to start at
2730 * @pfn: page frame number of kernel physical memory address
2731 * @size: size of mapping area
2732 * @prot: page protection flags for this mapping
2733 *
2734 * Note: this is only safe if the mm semaphore is held when called.
2735 *
2736 * Return: %0 on success, negative error code otherwise.
2737 */
2738int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2739 unsigned long pfn, unsigned long size, pgprot_t prot)
2740{
2741 int err;
2742
2743 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2744 if (err)
2745 return -EINVAL;
2746
2747 err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2748 if (err)
2749 untrack_pfn(vma, pfn, PAGE_ALIGN(size), true);
2750 return err;
2751}
2752EXPORT_SYMBOL(remap_pfn_range);
2753
2754/**
2755 * vm_iomap_memory - remap memory to userspace
2756 * @vma: user vma to map to
2757 * @start: start of the physical memory to be mapped
2758 * @len: size of area
2759 *
2760 * This is a simplified io_remap_pfn_range() for common driver use. The
2761 * driver just needs to give us the physical memory range to be mapped,
2762 * we'll figure out the rest from the vma information.
2763 *
2764 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2765 * whatever write-combining details or similar.
2766 *
2767 * Return: %0 on success, negative error code otherwise.
2768 */
2769int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2770{
2771 unsigned long vm_len, pfn, pages;
2772
2773 /* Check that the physical memory area passed in looks valid */
2774 if (start + len < start)
2775 return -EINVAL;
2776 /*
2777 * You *really* shouldn't map things that aren't page-aligned,
2778 * but we've historically allowed it because IO memory might
2779 * just have smaller alignment.
2780 */
2781 len += start & ~PAGE_MASK;
2782 pfn = start >> PAGE_SHIFT;
2783 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2784 if (pfn + pages < pfn)
2785 return -EINVAL;
2786
2787 /* We start the mapping 'vm_pgoff' pages into the area */
2788 if (vma->vm_pgoff > pages)
2789 return -EINVAL;
2790 pfn += vma->vm_pgoff;
2791 pages -= vma->vm_pgoff;
2792
2793 /* Can we fit all of the mapping? */
2794 vm_len = vma->vm_end - vma->vm_start;
2795 if (vm_len >> PAGE_SHIFT > pages)
2796 return -EINVAL;
2797
2798 /* Ok, let it rip */
2799 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2800}
2801EXPORT_SYMBOL(vm_iomap_memory);
2802
2803static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2804 unsigned long addr, unsigned long end,
2805 pte_fn_t fn, void *data, bool create,
2806 pgtbl_mod_mask *mask)
2807{
2808 pte_t *pte, *mapped_pte;
2809 int err = 0;
2810 spinlock_t *ptl;
2811
2812 if (create) {
2813 mapped_pte = pte = (mm == &init_mm) ?
2814 pte_alloc_kernel_track(pmd, addr, mask) :
2815 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2816 if (!pte)
2817 return -ENOMEM;
2818 } else {
2819 mapped_pte = pte = (mm == &init_mm) ?
2820 pte_offset_kernel(pmd, addr) :
2821 pte_offset_map_lock(mm, pmd, addr, &ptl);
2822 if (!pte)
2823 return -EINVAL;
2824 }
2825
2826 arch_enter_lazy_mmu_mode();
2827
2828 if (fn) {
2829 do {
2830 if (create || !pte_none(ptep_get(pte))) {
2831 err = fn(pte++, addr, data);
2832 if (err)
2833 break;
2834 }
2835 } while (addr += PAGE_SIZE, addr != end);
2836 }
2837 *mask |= PGTBL_PTE_MODIFIED;
2838
2839 arch_leave_lazy_mmu_mode();
2840
2841 if (mm != &init_mm)
2842 pte_unmap_unlock(mapped_pte, ptl);
2843 return err;
2844}
2845
2846static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2847 unsigned long addr, unsigned long end,
2848 pte_fn_t fn, void *data, bool create,
2849 pgtbl_mod_mask *mask)
2850{
2851 pmd_t *pmd;
2852 unsigned long next;
2853 int err = 0;
2854
2855 BUG_ON(pud_leaf(*pud));
2856
2857 if (create) {
2858 pmd = pmd_alloc_track(mm, pud, addr, mask);
2859 if (!pmd)
2860 return -ENOMEM;
2861 } else {
2862 pmd = pmd_offset(pud, addr);
2863 }
2864 do {
2865 next = pmd_addr_end(addr, end);
2866 if (pmd_none(*pmd) && !create)
2867 continue;
2868 if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2869 return -EINVAL;
2870 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2871 if (!create)
2872 continue;
2873 pmd_clear_bad(pmd);
2874 }
2875 err = apply_to_pte_range(mm, pmd, addr, next,
2876 fn, data, create, mask);
2877 if (err)
2878 break;
2879 } while (pmd++, addr = next, addr != end);
2880
2881 return err;
2882}
2883
2884static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2885 unsigned long addr, unsigned long end,
2886 pte_fn_t fn, void *data, bool create,
2887 pgtbl_mod_mask *mask)
2888{
2889 pud_t *pud;
2890 unsigned long next;
2891 int err = 0;
2892
2893 if (create) {
2894 pud = pud_alloc_track(mm, p4d, addr, mask);
2895 if (!pud)
2896 return -ENOMEM;
2897 } else {
2898 pud = pud_offset(p4d, addr);
2899 }
2900 do {
2901 next = pud_addr_end(addr, end);
2902 if (pud_none(*pud) && !create)
2903 continue;
2904 if (WARN_ON_ONCE(pud_leaf(*pud)))
2905 return -EINVAL;
2906 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2907 if (!create)
2908 continue;
2909 pud_clear_bad(pud);
2910 }
2911 err = apply_to_pmd_range(mm, pud, addr, next,
2912 fn, data, create, mask);
2913 if (err)
2914 break;
2915 } while (pud++, addr = next, addr != end);
2916
2917 return err;
2918}
2919
2920static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2921 unsigned long addr, unsigned long end,
2922 pte_fn_t fn, void *data, bool create,
2923 pgtbl_mod_mask *mask)
2924{
2925 p4d_t *p4d;
2926 unsigned long next;
2927 int err = 0;
2928
2929 if (create) {
2930 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2931 if (!p4d)
2932 return -ENOMEM;
2933 } else {
2934 p4d = p4d_offset(pgd, addr);
2935 }
2936 do {
2937 next = p4d_addr_end(addr, end);
2938 if (p4d_none(*p4d) && !create)
2939 continue;
2940 if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2941 return -EINVAL;
2942 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2943 if (!create)
2944 continue;
2945 p4d_clear_bad(p4d);
2946 }
2947 err = apply_to_pud_range(mm, p4d, addr, next,
2948 fn, data, create, mask);
2949 if (err)
2950 break;
2951 } while (p4d++, addr = next, addr != end);
2952
2953 return err;
2954}
2955
2956static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2957 unsigned long size, pte_fn_t fn,
2958 void *data, bool create)
2959{
2960 pgd_t *pgd;
2961 unsigned long start = addr, next;
2962 unsigned long end = addr + size;
2963 pgtbl_mod_mask mask = 0;
2964 int err = 0;
2965
2966 if (WARN_ON(addr >= end))
2967 return -EINVAL;
2968
2969 pgd = pgd_offset(mm, addr);
2970 do {
2971 next = pgd_addr_end(addr, end);
2972 if (pgd_none(*pgd) && !create)
2973 continue;
2974 if (WARN_ON_ONCE(pgd_leaf(*pgd))) {
2975 err = -EINVAL;
2976 break;
2977 }
2978 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2979 if (!create)
2980 continue;
2981 pgd_clear_bad(pgd);
2982 }
2983 err = apply_to_p4d_range(mm, pgd, addr, next,
2984 fn, data, create, &mask);
2985 if (err)
2986 break;
2987 } while (pgd++, addr = next, addr != end);
2988
2989 if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2990 arch_sync_kernel_mappings(start, start + size);
2991
2992 return err;
2993}
2994
2995/*
2996 * Scan a region of virtual memory, filling in page tables as necessary
2997 * and calling a provided function on each leaf page table.
2998 */
2999int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
3000 unsigned long size, pte_fn_t fn, void *data)
3001{
3002 return __apply_to_page_range(mm, addr, size, fn, data, true);
3003}
3004EXPORT_SYMBOL_GPL(apply_to_page_range);
3005
3006/*
3007 * Scan a region of virtual memory, calling a provided function on
3008 * each leaf page table where it exists.
3009 *
3010 * Unlike apply_to_page_range, this does _not_ fill in page tables
3011 * where they are absent.
3012 */
3013int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
3014 unsigned long size, pte_fn_t fn, void *data)
3015{
3016 return __apply_to_page_range(mm, addr, size, fn, data, false);
3017}
3018EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
3019
3020/*
3021 * handle_pte_fault chooses page fault handler according to an entry which was
3022 * read non-atomically. Before making any commitment, on those architectures
3023 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
3024 * parts, do_swap_page must check under lock before unmapping the pte and
3025 * proceeding (but do_wp_page is only called after already making such a check;
3026 * and do_anonymous_page can safely check later on).
3027 */
3028static inline int pte_unmap_same(struct vm_fault *vmf)
3029{
3030 int same = 1;
3031#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
3032 if (sizeof(pte_t) > sizeof(unsigned long)) {
3033 spin_lock(vmf->ptl);
3034 same = pte_same(ptep_get(vmf->pte), vmf->orig_pte);
3035 spin_unlock(vmf->ptl);
3036 }
3037#endif
3038 pte_unmap(vmf->pte);
3039 vmf->pte = NULL;
3040 return same;
3041}
3042
3043/*
3044 * Return:
3045 * 0: copied succeeded
3046 * -EHWPOISON: copy failed due to hwpoison in source page
3047 * -EAGAIN: copied failed (some other reason)
3048 */
3049static inline int __wp_page_copy_user(struct page *dst, struct page *src,
3050 struct vm_fault *vmf)
3051{
3052 int ret;
3053 void *kaddr;
3054 void __user *uaddr;
3055 struct vm_area_struct *vma = vmf->vma;
3056 struct mm_struct *mm = vma->vm_mm;
3057 unsigned long addr = vmf->address;
3058
3059 if (likely(src)) {
3060 if (copy_mc_user_highpage(dst, src, addr, vma))
3061 return -EHWPOISON;
3062 return 0;
3063 }
3064
3065 /*
3066 * If the source page was a PFN mapping, we don't have
3067 * a "struct page" for it. We do a best-effort copy by
3068 * just copying from the original user address. If that
3069 * fails, we just zero-fill it. Live with it.
3070 */
3071 kaddr = kmap_local_page(dst);
3072 pagefault_disable();
3073 uaddr = (void __user *)(addr & PAGE_MASK);
3074
3075 /*
3076 * On architectures with software "accessed" bits, we would
3077 * take a double page fault, so mark it accessed here.
3078 */
3079 vmf->pte = NULL;
3080 if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
3081 pte_t entry;
3082
3083 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
3084 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3085 /*
3086 * Other thread has already handled the fault
3087 * and update local tlb only
3088 */
3089 if (vmf->pte)
3090 update_mmu_tlb(vma, addr, vmf->pte);
3091 ret = -EAGAIN;
3092 goto pte_unlock;
3093 }
3094
3095 entry = pte_mkyoung(vmf->orig_pte);
3096 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
3097 update_mmu_cache_range(vmf, vma, addr, vmf->pte, 1);
3098 }
3099
3100 /*
3101 * This really shouldn't fail, because the page is there
3102 * in the page tables. But it might just be unreadable,
3103 * in which case we just give up and fill the result with
3104 * zeroes.
3105 */
3106 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
3107 if (vmf->pte)
3108 goto warn;
3109
3110 /* Re-validate under PTL if the page is still mapped */
3111 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
3112 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3113 /* The PTE changed under us, update local tlb */
3114 if (vmf->pte)
3115 update_mmu_tlb(vma, addr, vmf->pte);
3116 ret = -EAGAIN;
3117 goto pte_unlock;
3118 }
3119
3120 /*
3121 * The same page can be mapped back since last copy attempt.
3122 * Try to copy again under PTL.
3123 */
3124 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
3125 /*
3126 * Give a warn in case there can be some obscure
3127 * use-case
3128 */
3129warn:
3130 WARN_ON_ONCE(1);
3131 clear_page(kaddr);
3132 }
3133 }
3134
3135 ret = 0;
3136
3137pte_unlock:
3138 if (vmf->pte)
3139 pte_unmap_unlock(vmf->pte, vmf->ptl);
3140 pagefault_enable();
3141 kunmap_local(kaddr);
3142 flush_dcache_page(dst);
3143
3144 return ret;
3145}
3146
3147static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
3148{
3149 struct file *vm_file = vma->vm_file;
3150
3151 if (vm_file)
3152 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
3153
3154 /*
3155 * Special mappings (e.g. VDSO) do not have any file so fake
3156 * a default GFP_KERNEL for them.
3157 */
3158 return GFP_KERNEL;
3159}
3160
3161/*
3162 * Notify the address space that the page is about to become writable so that
3163 * it can prohibit this or wait for the page to get into an appropriate state.
3164 *
3165 * We do this without the lock held, so that it can sleep if it needs to.
3166 */
3167static vm_fault_t do_page_mkwrite(struct vm_fault *vmf, struct folio *folio)
3168{
3169 vm_fault_t ret;
3170 unsigned int old_flags = vmf->flags;
3171
3172 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3173
3174 if (vmf->vma->vm_file &&
3175 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
3176 return VM_FAULT_SIGBUS;
3177
3178 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
3179 /* Restore original flags so that caller is not surprised */
3180 vmf->flags = old_flags;
3181 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
3182 return ret;
3183 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
3184 folio_lock(folio);
3185 if (!folio->mapping) {
3186 folio_unlock(folio);
3187 return 0; /* retry */
3188 }
3189 ret |= VM_FAULT_LOCKED;
3190 } else
3191 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
3192 return ret;
3193}
3194
3195/*
3196 * Handle dirtying of a page in shared file mapping on a write fault.
3197 *
3198 * The function expects the page to be locked and unlocks it.
3199 */
3200static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
3201{
3202 struct vm_area_struct *vma = vmf->vma;
3203 struct address_space *mapping;
3204 struct folio *folio = page_folio(vmf->page);
3205 bool dirtied;
3206 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
3207
3208 dirtied = folio_mark_dirty(folio);
3209 VM_BUG_ON_FOLIO(folio_test_anon(folio), folio);
3210 /*
3211 * Take a local copy of the address_space - folio.mapping may be zeroed
3212 * by truncate after folio_unlock(). The address_space itself remains
3213 * pinned by vma->vm_file's reference. We rely on folio_unlock()'s
3214 * release semantics to prevent the compiler from undoing this copying.
3215 */
3216 mapping = folio_raw_mapping(folio);
3217 folio_unlock(folio);
3218
3219 if (!page_mkwrite)
3220 file_update_time(vma->vm_file);
3221
3222 /*
3223 * Throttle page dirtying rate down to writeback speed.
3224 *
3225 * mapping may be NULL here because some device drivers do not
3226 * set page.mapping but still dirty their pages
3227 *
3228 * Drop the mmap_lock before waiting on IO, if we can. The file
3229 * is pinning the mapping, as per above.
3230 */
3231 if ((dirtied || page_mkwrite) && mapping) {
3232 struct file *fpin;
3233
3234 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
3235 balance_dirty_pages_ratelimited(mapping);
3236 if (fpin) {
3237 fput(fpin);
3238 return VM_FAULT_COMPLETED;
3239 }
3240 }
3241
3242 return 0;
3243}
3244
3245/*
3246 * Handle write page faults for pages that can be reused in the current vma
3247 *
3248 * This can happen either due to the mapping being with the VM_SHARED flag,
3249 * or due to us being the last reference standing to the page. In either
3250 * case, all we need to do here is to mark the page as writable and update
3251 * any related book-keeping.
3252 */
3253static inline void wp_page_reuse(struct vm_fault *vmf, struct folio *folio)
3254 __releases(vmf->ptl)
3255{
3256 struct vm_area_struct *vma = vmf->vma;
3257 pte_t entry;
3258
3259 VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE));
3260 VM_WARN_ON(is_zero_pfn(pte_pfn(vmf->orig_pte)));
3261
3262 if (folio) {
3263 VM_BUG_ON(folio_test_anon(folio) &&
3264 !PageAnonExclusive(vmf->page));
3265 /*
3266 * Clear the folio's cpupid information as the existing
3267 * information potentially belongs to a now completely
3268 * unrelated process.
3269 */
3270 folio_xchg_last_cpupid(folio, (1 << LAST_CPUPID_SHIFT) - 1);
3271 }
3272
3273 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3274 entry = pte_mkyoung(vmf->orig_pte);
3275 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3276 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
3277 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
3278 pte_unmap_unlock(vmf->pte, vmf->ptl);
3279 count_vm_event(PGREUSE);
3280}
3281
3282/*
3283 * We could add a bitflag somewhere, but for now, we know that all
3284 * vm_ops that have a ->map_pages have been audited and don't need
3285 * the mmap_lock to be held.
3286 */
3287static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf)
3288{
3289 struct vm_area_struct *vma = vmf->vma;
3290
3291 if (vma->vm_ops->map_pages || !(vmf->flags & FAULT_FLAG_VMA_LOCK))
3292 return 0;
3293 vma_end_read(vma);
3294 return VM_FAULT_RETRY;
3295}
3296
3297/**
3298 * __vmf_anon_prepare - Prepare to handle an anonymous fault.
3299 * @vmf: The vm_fault descriptor passed from the fault handler.
3300 *
3301 * When preparing to insert an anonymous page into a VMA from a
3302 * fault handler, call this function rather than anon_vma_prepare().
3303 * If this vma does not already have an associated anon_vma and we are
3304 * only protected by the per-VMA lock, the caller must retry with the
3305 * mmap_lock held. __anon_vma_prepare() will look at adjacent VMAs to
3306 * determine if this VMA can share its anon_vma, and that's not safe to
3307 * do with only the per-VMA lock held for this VMA.
3308 *
3309 * Return: 0 if fault handling can proceed. Any other value should be
3310 * returned to the caller.
3311 */
3312vm_fault_t __vmf_anon_prepare(struct vm_fault *vmf)
3313{
3314 struct vm_area_struct *vma = vmf->vma;
3315 vm_fault_t ret = 0;
3316
3317 if (likely(vma->anon_vma))
3318 return 0;
3319 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
3320 if (!mmap_read_trylock(vma->vm_mm))
3321 return VM_FAULT_RETRY;
3322 }
3323 if (__anon_vma_prepare(vma))
3324 ret = VM_FAULT_OOM;
3325 if (vmf->flags & FAULT_FLAG_VMA_LOCK)
3326 mmap_read_unlock(vma->vm_mm);
3327 return ret;
3328}
3329
3330/*
3331 * Handle the case of a page which we actually need to copy to a new page,
3332 * either due to COW or unsharing.
3333 *
3334 * Called with mmap_lock locked and the old page referenced, but
3335 * without the ptl held.
3336 *
3337 * High level logic flow:
3338 *
3339 * - Allocate a page, copy the content of the old page to the new one.
3340 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
3341 * - Take the PTL. If the pte changed, bail out and release the allocated page
3342 * - If the pte is still the way we remember it, update the page table and all
3343 * relevant references. This includes dropping the reference the page-table
3344 * held to the old page, as well as updating the rmap.
3345 * - In any case, unlock the PTL and drop the reference we took to the old page.
3346 */
3347static vm_fault_t wp_page_copy(struct vm_fault *vmf)
3348{
3349 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3350 struct vm_area_struct *vma = vmf->vma;
3351 struct mm_struct *mm = vma->vm_mm;
3352 struct folio *old_folio = NULL;
3353 struct folio *new_folio = NULL;
3354 pte_t entry;
3355 int page_copied = 0;
3356 struct mmu_notifier_range range;
3357 vm_fault_t ret;
3358 bool pfn_is_zero;
3359
3360 delayacct_wpcopy_start();
3361
3362 if (vmf->page)
3363 old_folio = page_folio(vmf->page);
3364 ret = vmf_anon_prepare(vmf);
3365 if (unlikely(ret))
3366 goto out;
3367
3368 pfn_is_zero = is_zero_pfn(pte_pfn(vmf->orig_pte));
3369 new_folio = folio_prealloc(mm, vma, vmf->address, pfn_is_zero);
3370 if (!new_folio)
3371 goto oom;
3372
3373 if (!pfn_is_zero) {
3374 int err;
3375
3376 err = __wp_page_copy_user(&new_folio->page, vmf->page, vmf);
3377 if (err) {
3378 /*
3379 * COW failed, if the fault was solved by other,
3380 * it's fine. If not, userspace would re-fault on
3381 * the same address and we will handle the fault
3382 * from the second attempt.
3383 * The -EHWPOISON case will not be retried.
3384 */
3385 folio_put(new_folio);
3386 if (old_folio)
3387 folio_put(old_folio);
3388
3389 delayacct_wpcopy_end();
3390 return err == -EHWPOISON ? VM_FAULT_HWPOISON : 0;
3391 }
3392 kmsan_copy_page_meta(&new_folio->page, vmf->page);
3393 }
3394
3395 __folio_mark_uptodate(new_folio);
3396
3397 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
3398 vmf->address & PAGE_MASK,
3399 (vmf->address & PAGE_MASK) + PAGE_SIZE);
3400 mmu_notifier_invalidate_range_start(&range);
3401
3402 /*
3403 * Re-check the pte - we dropped the lock
3404 */
3405 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3406 if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3407 if (old_folio) {
3408 if (!folio_test_anon(old_folio)) {
3409 dec_mm_counter(mm, mm_counter_file(old_folio));
3410 inc_mm_counter(mm, MM_ANONPAGES);
3411 }
3412 } else {
3413 ksm_might_unmap_zero_page(mm, vmf->orig_pte);
3414 inc_mm_counter(mm, MM_ANONPAGES);
3415 }
3416 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3417 entry = mk_pte(&new_folio->page, vma->vm_page_prot);
3418 entry = pte_sw_mkyoung(entry);
3419 if (unlikely(unshare)) {
3420 if (pte_soft_dirty(vmf->orig_pte))
3421 entry = pte_mksoft_dirty(entry);
3422 if (pte_uffd_wp(vmf->orig_pte))
3423 entry = pte_mkuffd_wp(entry);
3424 } else {
3425 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3426 }
3427
3428 /*
3429 * Clear the pte entry and flush it first, before updating the
3430 * pte with the new entry, to keep TLBs on different CPUs in
3431 * sync. This code used to set the new PTE then flush TLBs, but
3432 * that left a window where the new PTE could be loaded into
3433 * some TLBs while the old PTE remains in others.
3434 */
3435 ptep_clear_flush(vma, vmf->address, vmf->pte);
3436 folio_add_new_anon_rmap(new_folio, vma, vmf->address, RMAP_EXCLUSIVE);
3437 folio_add_lru_vma(new_folio, vma);
3438 BUG_ON(unshare && pte_write(entry));
3439 set_pte_at(mm, vmf->address, vmf->pte, entry);
3440 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
3441 if (old_folio) {
3442 /*
3443 * Only after switching the pte to the new page may
3444 * we remove the mapcount here. Otherwise another
3445 * process may come and find the rmap count decremented
3446 * before the pte is switched to the new page, and
3447 * "reuse" the old page writing into it while our pte
3448 * here still points into it and can be read by other
3449 * threads.
3450 *
3451 * The critical issue is to order this
3452 * folio_remove_rmap_pte() with the ptp_clear_flush
3453 * above. Those stores are ordered by (if nothing else,)
3454 * the barrier present in the atomic_add_negative
3455 * in folio_remove_rmap_pte();
3456 *
3457 * Then the TLB flush in ptep_clear_flush ensures that
3458 * no process can access the old page before the
3459 * decremented mapcount is visible. And the old page
3460 * cannot be reused until after the decremented
3461 * mapcount is visible. So transitively, TLBs to
3462 * old page will be flushed before it can be reused.
3463 */
3464 folio_remove_rmap_pte(old_folio, vmf->page, vma);
3465 }
3466
3467 /* Free the old page.. */
3468 new_folio = old_folio;
3469 page_copied = 1;
3470 pte_unmap_unlock(vmf->pte, vmf->ptl);
3471 } else if (vmf->pte) {
3472 update_mmu_tlb(vma, vmf->address, vmf->pte);
3473 pte_unmap_unlock(vmf->pte, vmf->ptl);
3474 }
3475
3476 mmu_notifier_invalidate_range_end(&range);
3477
3478 if (new_folio)
3479 folio_put(new_folio);
3480 if (old_folio) {
3481 if (page_copied)
3482 free_swap_cache(old_folio);
3483 folio_put(old_folio);
3484 }
3485
3486 delayacct_wpcopy_end();
3487 return 0;
3488oom:
3489 ret = VM_FAULT_OOM;
3490out:
3491 if (old_folio)
3492 folio_put(old_folio);
3493
3494 delayacct_wpcopy_end();
3495 return ret;
3496}
3497
3498/**
3499 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3500 * writeable once the page is prepared
3501 *
3502 * @vmf: structure describing the fault
3503 * @folio: the folio of vmf->page
3504 *
3505 * This function handles all that is needed to finish a write page fault in a
3506 * shared mapping due to PTE being read-only once the mapped page is prepared.
3507 * It handles locking of PTE and modifying it.
3508 *
3509 * The function expects the page to be locked or other protection against
3510 * concurrent faults / writeback (such as DAX radix tree locks).
3511 *
3512 * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3513 * we acquired PTE lock.
3514 */
3515static vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf, struct folio *folio)
3516{
3517 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3518 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3519 &vmf->ptl);
3520 if (!vmf->pte)
3521 return VM_FAULT_NOPAGE;
3522 /*
3523 * We might have raced with another page fault while we released the
3524 * pte_offset_map_lock.
3525 */
3526 if (!pte_same(ptep_get(vmf->pte), vmf->orig_pte)) {
3527 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3528 pte_unmap_unlock(vmf->pte, vmf->ptl);
3529 return VM_FAULT_NOPAGE;
3530 }
3531 wp_page_reuse(vmf, folio);
3532 return 0;
3533}
3534
3535/*
3536 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3537 * mapping
3538 */
3539static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3540{
3541 struct vm_area_struct *vma = vmf->vma;
3542
3543 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3544 vm_fault_t ret;
3545
3546 pte_unmap_unlock(vmf->pte, vmf->ptl);
3547 ret = vmf_can_call_fault(vmf);
3548 if (ret)
3549 return ret;
3550
3551 vmf->flags |= FAULT_FLAG_MKWRITE;
3552 ret = vma->vm_ops->pfn_mkwrite(vmf);
3553 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3554 return ret;
3555 return finish_mkwrite_fault(vmf, NULL);
3556 }
3557 wp_page_reuse(vmf, NULL);
3558 return 0;
3559}
3560
3561static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio)
3562 __releases(vmf->ptl)
3563{
3564 struct vm_area_struct *vma = vmf->vma;
3565 vm_fault_t ret = 0;
3566
3567 folio_get(folio);
3568
3569 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3570 vm_fault_t tmp;
3571
3572 pte_unmap_unlock(vmf->pte, vmf->ptl);
3573 tmp = vmf_can_call_fault(vmf);
3574 if (tmp) {
3575 folio_put(folio);
3576 return tmp;
3577 }
3578
3579 tmp = do_page_mkwrite(vmf, folio);
3580 if (unlikely(!tmp || (tmp &
3581 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3582 folio_put(folio);
3583 return tmp;
3584 }
3585 tmp = finish_mkwrite_fault(vmf, folio);
3586 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3587 folio_unlock(folio);
3588 folio_put(folio);
3589 return tmp;
3590 }
3591 } else {
3592 wp_page_reuse(vmf, folio);
3593 folio_lock(folio);
3594 }
3595 ret |= fault_dirty_shared_page(vmf);
3596 folio_put(folio);
3597
3598 return ret;
3599}
3600
3601static bool wp_can_reuse_anon_folio(struct folio *folio,
3602 struct vm_area_struct *vma)
3603{
3604 /*
3605 * We could currently only reuse a subpage of a large folio if no
3606 * other subpages of the large folios are still mapped. However,
3607 * let's just consistently not reuse subpages even if we could
3608 * reuse in that scenario, and give back a large folio a bit
3609 * sooner.
3610 */
3611 if (folio_test_large(folio))
3612 return false;
3613
3614 /*
3615 * We have to verify under folio lock: these early checks are
3616 * just an optimization to avoid locking the folio and freeing
3617 * the swapcache if there is little hope that we can reuse.
3618 *
3619 * KSM doesn't necessarily raise the folio refcount.
3620 */
3621 if (folio_test_ksm(folio) || folio_ref_count(folio) > 3)
3622 return false;
3623 if (!folio_test_lru(folio))
3624 /*
3625 * We cannot easily detect+handle references from
3626 * remote LRU caches or references to LRU folios.
3627 */
3628 lru_add_drain();
3629 if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio))
3630 return false;
3631 if (!folio_trylock(folio))
3632 return false;
3633 if (folio_test_swapcache(folio))
3634 folio_free_swap(folio);
3635 if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) {
3636 folio_unlock(folio);
3637 return false;
3638 }
3639 /*
3640 * Ok, we've got the only folio reference from our mapping
3641 * and the folio is locked, it's dark out, and we're wearing
3642 * sunglasses. Hit it.
3643 */
3644 folio_move_anon_rmap(folio, vma);
3645 folio_unlock(folio);
3646 return true;
3647}
3648
3649/*
3650 * This routine handles present pages, when
3651 * * users try to write to a shared page (FAULT_FLAG_WRITE)
3652 * * GUP wants to take a R/O pin on a possibly shared anonymous page
3653 * (FAULT_FLAG_UNSHARE)
3654 *
3655 * It is done by copying the page to a new address and decrementing the
3656 * shared-page counter for the old page.
3657 *
3658 * Note that this routine assumes that the protection checks have been
3659 * done by the caller (the low-level page fault routine in most cases).
3660 * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've
3661 * done any necessary COW.
3662 *
3663 * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even
3664 * though the page will change only once the write actually happens. This
3665 * avoids a few races, and potentially makes it more efficient.
3666 *
3667 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3668 * but allow concurrent faults), with pte both mapped and locked.
3669 * We return with mmap_lock still held, but pte unmapped and unlocked.
3670 */
3671static vm_fault_t do_wp_page(struct vm_fault *vmf)
3672 __releases(vmf->ptl)
3673{
3674 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3675 struct vm_area_struct *vma = vmf->vma;
3676 struct folio *folio = NULL;
3677 pte_t pte;
3678
3679 if (likely(!unshare)) {
3680 if (userfaultfd_pte_wp(vma, ptep_get(vmf->pte))) {
3681 if (!userfaultfd_wp_async(vma)) {
3682 pte_unmap_unlock(vmf->pte, vmf->ptl);
3683 return handle_userfault(vmf, VM_UFFD_WP);
3684 }
3685
3686 /*
3687 * Nothing needed (cache flush, TLB invalidations,
3688 * etc.) because we're only removing the uffd-wp bit,
3689 * which is completely invisible to the user.
3690 */
3691 pte = pte_clear_uffd_wp(ptep_get(vmf->pte));
3692
3693 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3694 /*
3695 * Update this to be prepared for following up CoW
3696 * handling
3697 */
3698 vmf->orig_pte = pte;
3699 }
3700
3701 /*
3702 * Userfaultfd write-protect can defer flushes. Ensure the TLB
3703 * is flushed in this case before copying.
3704 */
3705 if (unlikely(userfaultfd_wp(vmf->vma) &&
3706 mm_tlb_flush_pending(vmf->vma->vm_mm)))
3707 flush_tlb_page(vmf->vma, vmf->address);
3708 }
3709
3710 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3711
3712 if (vmf->page)
3713 folio = page_folio(vmf->page);
3714
3715 /*
3716 * Shared mapping: we are guaranteed to have VM_WRITE and
3717 * FAULT_FLAG_WRITE set at this point.
3718 */
3719 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
3720 /*
3721 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3722 * VM_PFNMAP VMA.
3723 *
3724 * We should not cow pages in a shared writeable mapping.
3725 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3726 */
3727 if (!vmf->page)
3728 return wp_pfn_shared(vmf);
3729 return wp_page_shared(vmf, folio);
3730 }
3731
3732 /*
3733 * Private mapping: create an exclusive anonymous page copy if reuse
3734 * is impossible. We might miss VM_WRITE for FOLL_FORCE handling.
3735 *
3736 * If we encounter a page that is marked exclusive, we must reuse
3737 * the page without further checks.
3738 */
3739 if (folio && folio_test_anon(folio) &&
3740 (PageAnonExclusive(vmf->page) || wp_can_reuse_anon_folio(folio, vma))) {
3741 if (!PageAnonExclusive(vmf->page))
3742 SetPageAnonExclusive(vmf->page);
3743 if (unlikely(unshare)) {
3744 pte_unmap_unlock(vmf->pte, vmf->ptl);
3745 return 0;
3746 }
3747 wp_page_reuse(vmf, folio);
3748 return 0;
3749 }
3750 /*
3751 * Ok, we need to copy. Oh, well..
3752 */
3753 if (folio)
3754 folio_get(folio);
3755
3756 pte_unmap_unlock(vmf->pte, vmf->ptl);
3757#ifdef CONFIG_KSM
3758 if (folio && folio_test_ksm(folio))
3759 count_vm_event(COW_KSM);
3760#endif
3761 return wp_page_copy(vmf);
3762}
3763
3764static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3765 unsigned long start_addr, unsigned long end_addr,
3766 struct zap_details *details)
3767{
3768 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3769}
3770
3771static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3772 pgoff_t first_index,
3773 pgoff_t last_index,
3774 struct zap_details *details)
3775{
3776 struct vm_area_struct *vma;
3777 pgoff_t vba, vea, zba, zea;
3778
3779 vma_interval_tree_foreach(vma, root, first_index, last_index) {
3780 vba = vma->vm_pgoff;
3781 vea = vba + vma_pages(vma) - 1;
3782 zba = max(first_index, vba);
3783 zea = min(last_index, vea);
3784
3785 unmap_mapping_range_vma(vma,
3786 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3787 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3788 details);
3789 }
3790}
3791
3792/**
3793 * unmap_mapping_folio() - Unmap single folio from processes.
3794 * @folio: The locked folio to be unmapped.
3795 *
3796 * Unmap this folio from any userspace process which still has it mmaped.
3797 * Typically, for efficiency, the range of nearby pages has already been
3798 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
3799 * truncation or invalidation holds the lock on a folio, it may find that
3800 * the page has been remapped again: and then uses unmap_mapping_folio()
3801 * to unmap it finally.
3802 */
3803void unmap_mapping_folio(struct folio *folio)
3804{
3805 struct address_space *mapping = folio->mapping;
3806 struct zap_details details = { };
3807 pgoff_t first_index;
3808 pgoff_t last_index;
3809
3810 VM_BUG_ON(!folio_test_locked(folio));
3811
3812 first_index = folio->index;
3813 last_index = folio_next_index(folio) - 1;
3814
3815 details.even_cows = false;
3816 details.single_folio = folio;
3817 details.zap_flags = ZAP_FLAG_DROP_MARKER;
3818
3819 i_mmap_lock_read(mapping);
3820 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3821 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3822 last_index, &details);
3823 i_mmap_unlock_read(mapping);
3824}
3825
3826/**
3827 * unmap_mapping_pages() - Unmap pages from processes.
3828 * @mapping: The address space containing pages to be unmapped.
3829 * @start: Index of first page to be unmapped.
3830 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3831 * @even_cows: Whether to unmap even private COWed pages.
3832 *
3833 * Unmap the pages in this address space from any userspace process which
3834 * has them mmaped. Generally, you want to remove COWed pages as well when
3835 * a file is being truncated, but not when invalidating pages from the page
3836 * cache.
3837 */
3838void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3839 pgoff_t nr, bool even_cows)
3840{
3841 struct zap_details details = { };
3842 pgoff_t first_index = start;
3843 pgoff_t last_index = start + nr - 1;
3844
3845 details.even_cows = even_cows;
3846 if (last_index < first_index)
3847 last_index = ULONG_MAX;
3848
3849 i_mmap_lock_read(mapping);
3850 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3851 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3852 last_index, &details);
3853 i_mmap_unlock_read(mapping);
3854}
3855EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3856
3857/**
3858 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3859 * address_space corresponding to the specified byte range in the underlying
3860 * file.
3861 *
3862 * @mapping: the address space containing mmaps to be unmapped.
3863 * @holebegin: byte in first page to unmap, relative to the start of
3864 * the underlying file. This will be rounded down to a PAGE_SIZE
3865 * boundary. Note that this is different from truncate_pagecache(), which
3866 * must keep the partial page. In contrast, we must get rid of
3867 * partial pages.
3868 * @holelen: size of prospective hole in bytes. This will be rounded
3869 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3870 * end of the file.
3871 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3872 * but 0 when invalidating pagecache, don't throw away private data.
3873 */
3874void unmap_mapping_range(struct address_space *mapping,
3875 loff_t const holebegin, loff_t const holelen, int even_cows)
3876{
3877 pgoff_t hba = (pgoff_t)(holebegin) >> PAGE_SHIFT;
3878 pgoff_t hlen = ((pgoff_t)(holelen) + PAGE_SIZE - 1) >> PAGE_SHIFT;
3879
3880 /* Check for overflow. */
3881 if (sizeof(holelen) > sizeof(hlen)) {
3882 long long holeend =
3883 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3884 if (holeend & ~(long long)ULONG_MAX)
3885 hlen = ULONG_MAX - hba + 1;
3886 }
3887
3888 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3889}
3890EXPORT_SYMBOL(unmap_mapping_range);
3891
3892/*
3893 * Restore a potential device exclusive pte to a working pte entry
3894 */
3895static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3896{
3897 struct folio *folio = page_folio(vmf->page);
3898 struct vm_area_struct *vma = vmf->vma;
3899 struct mmu_notifier_range range;
3900 vm_fault_t ret;
3901
3902 /*
3903 * We need a reference to lock the folio because we don't hold
3904 * the PTL so a racing thread can remove the device-exclusive
3905 * entry and unmap it. If the folio is free the entry must
3906 * have been removed already. If it happens to have already
3907 * been re-allocated after being freed all we do is lock and
3908 * unlock it.
3909 */
3910 if (!folio_try_get(folio))
3911 return 0;
3912
3913 ret = folio_lock_or_retry(folio, vmf);
3914 if (ret) {
3915 folio_put(folio);
3916 return ret;
3917 }
3918 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0,
3919 vma->vm_mm, vmf->address & PAGE_MASK,
3920 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3921 mmu_notifier_invalidate_range_start(&range);
3922
3923 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3924 &vmf->ptl);
3925 if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
3926 restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
3927
3928 if (vmf->pte)
3929 pte_unmap_unlock(vmf->pte, vmf->ptl);
3930 folio_unlock(folio);
3931 folio_put(folio);
3932
3933 mmu_notifier_invalidate_range_end(&range);
3934 return 0;
3935}
3936
3937static inline bool should_try_to_free_swap(struct folio *folio,
3938 struct vm_area_struct *vma,
3939 unsigned int fault_flags)
3940{
3941 if (!folio_test_swapcache(folio))
3942 return false;
3943 if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
3944 folio_test_mlocked(folio))
3945 return true;
3946 /*
3947 * If we want to map a page that's in the swapcache writable, we
3948 * have to detect via the refcount if we're really the exclusive
3949 * user. Try freeing the swapcache to get rid of the swapcache
3950 * reference only in case it's likely that we'll be the exlusive user.
3951 */
3952 return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
3953 folio_ref_count(folio) == (1 + folio_nr_pages(folio));
3954}
3955
3956static vm_fault_t pte_marker_clear(struct vm_fault *vmf)
3957{
3958 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
3959 vmf->address, &vmf->ptl);
3960 if (!vmf->pte)
3961 return 0;
3962 /*
3963 * Be careful so that we will only recover a special uffd-wp pte into a
3964 * none pte. Otherwise it means the pte could have changed, so retry.
3965 *
3966 * This should also cover the case where e.g. the pte changed
3967 * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_POISONED.
3968 * So is_pte_marker() check is not enough to safely drop the pte.
3969 */
3970 if (pte_same(vmf->orig_pte, ptep_get(vmf->pte)))
3971 pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte);
3972 pte_unmap_unlock(vmf->pte, vmf->ptl);
3973 return 0;
3974}
3975
3976static vm_fault_t do_pte_missing(struct vm_fault *vmf)
3977{
3978 if (vma_is_anonymous(vmf->vma))
3979 return do_anonymous_page(vmf);
3980 else
3981 return do_fault(vmf);
3982}
3983
3984/*
3985 * This is actually a page-missing access, but with uffd-wp special pte
3986 * installed. It means this pte was wr-protected before being unmapped.
3987 */
3988static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf)
3989{
3990 /*
3991 * Just in case there're leftover special ptes even after the region
3992 * got unregistered - we can simply clear them.
3993 */
3994 if (unlikely(!userfaultfd_wp(vmf->vma)))
3995 return pte_marker_clear(vmf);
3996
3997 return do_pte_missing(vmf);
3998}
3999
4000static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
4001{
4002 swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte);
4003 unsigned long marker = pte_marker_get(entry);
4004
4005 /*
4006 * PTE markers should never be empty. If anything weird happened,
4007 * the best thing to do is to kill the process along with its mm.
4008 */
4009 if (WARN_ON_ONCE(!marker))
4010 return VM_FAULT_SIGBUS;
4011
4012 /* Higher priority than uffd-wp when data corrupted */
4013 if (marker & PTE_MARKER_POISONED)
4014 return VM_FAULT_HWPOISON;
4015
4016 /* Hitting a guard page is always a fatal condition. */
4017 if (marker & PTE_MARKER_GUARD)
4018 return VM_FAULT_SIGSEGV;
4019
4020 if (pte_marker_entry_uffd_wp(entry))
4021 return pte_marker_handle_uffd_wp(vmf);
4022
4023 /* This is an unknown pte marker */
4024 return VM_FAULT_SIGBUS;
4025}
4026
4027static struct folio *__alloc_swap_folio(struct vm_fault *vmf)
4028{
4029 struct vm_area_struct *vma = vmf->vma;
4030 struct folio *folio;
4031 swp_entry_t entry;
4032
4033 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vmf->address);
4034 if (!folio)
4035 return NULL;
4036
4037 entry = pte_to_swp_entry(vmf->orig_pte);
4038 if (mem_cgroup_swapin_charge_folio(folio, vma->vm_mm,
4039 GFP_KERNEL, entry)) {
4040 folio_put(folio);
4041 return NULL;
4042 }
4043
4044 return folio;
4045}
4046
4047#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4048static inline int non_swapcache_batch(swp_entry_t entry, int max_nr)
4049{
4050 struct swap_info_struct *si = swp_swap_info(entry);
4051 pgoff_t offset = swp_offset(entry);
4052 int i;
4053
4054 /*
4055 * While allocating a large folio and doing swap_read_folio, which is
4056 * the case the being faulted pte doesn't have swapcache. We need to
4057 * ensure all PTEs have no cache as well, otherwise, we might go to
4058 * swap devices while the content is in swapcache.
4059 */
4060 for (i = 0; i < max_nr; i++) {
4061 if ((si->swap_map[offset + i] & SWAP_HAS_CACHE))
4062 return i;
4063 }
4064
4065 return i;
4066}
4067
4068/*
4069 * Check if the PTEs within a range are contiguous swap entries
4070 * and have consistent swapcache, zeromap.
4071 */
4072static bool can_swapin_thp(struct vm_fault *vmf, pte_t *ptep, int nr_pages)
4073{
4074 unsigned long addr;
4075 swp_entry_t entry;
4076 int idx;
4077 pte_t pte;
4078
4079 addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE);
4080 idx = (vmf->address - addr) / PAGE_SIZE;
4081 pte = ptep_get(ptep);
4082
4083 if (!pte_same(pte, pte_move_swp_offset(vmf->orig_pte, -idx)))
4084 return false;
4085 entry = pte_to_swp_entry(pte);
4086 if (swap_pte_batch(ptep, nr_pages, pte) != nr_pages)
4087 return false;
4088
4089 /*
4090 * swap_read_folio() can't handle the case a large folio is hybridly
4091 * from different backends. And they are likely corner cases. Similar
4092 * things might be added once zswap support large folios.
4093 */
4094 if (unlikely(swap_zeromap_batch(entry, nr_pages, NULL) != nr_pages))
4095 return false;
4096 if (unlikely(non_swapcache_batch(entry, nr_pages) != nr_pages))
4097 return false;
4098
4099 return true;
4100}
4101
4102static inline unsigned long thp_swap_suitable_orders(pgoff_t swp_offset,
4103 unsigned long addr,
4104 unsigned long orders)
4105{
4106 int order, nr;
4107
4108 order = highest_order(orders);
4109
4110 /*
4111 * To swap in a THP with nr pages, we require that its first swap_offset
4112 * is aligned with that number, as it was when the THP was swapped out.
4113 * This helps filter out most invalid entries.
4114 */
4115 while (orders) {
4116 nr = 1 << order;
4117 if ((addr >> PAGE_SHIFT) % nr == swp_offset % nr)
4118 break;
4119 order = next_order(&orders, order);
4120 }
4121
4122 return orders;
4123}
4124
4125static struct folio *alloc_swap_folio(struct vm_fault *vmf)
4126{
4127 struct vm_area_struct *vma = vmf->vma;
4128 unsigned long orders;
4129 struct folio *folio;
4130 unsigned long addr;
4131 swp_entry_t entry;
4132 spinlock_t *ptl;
4133 pte_t *pte;
4134 gfp_t gfp;
4135 int order;
4136
4137 /*
4138 * If uffd is active for the vma we need per-page fault fidelity to
4139 * maintain the uffd semantics.
4140 */
4141 if (unlikely(userfaultfd_armed(vma)))
4142 goto fallback;
4143
4144 /*
4145 * A large swapped out folio could be partially or fully in zswap. We
4146 * lack handling for such cases, so fallback to swapping in order-0
4147 * folio.
4148 */
4149 if (!zswap_never_enabled())
4150 goto fallback;
4151
4152 entry = pte_to_swp_entry(vmf->orig_pte);
4153 /*
4154 * Get a list of all the (large) orders below PMD_ORDER that are enabled
4155 * and suitable for swapping THP.
4156 */
4157 orders = thp_vma_allowable_orders(vma, vma->vm_flags,
4158 TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
4159 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
4160 orders = thp_swap_suitable_orders(swp_offset(entry),
4161 vmf->address, orders);
4162
4163 if (!orders)
4164 goto fallback;
4165
4166 pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
4167 vmf->address & PMD_MASK, &ptl);
4168 if (unlikely(!pte))
4169 goto fallback;
4170
4171 /*
4172 * For do_swap_page, find the highest order where the aligned range is
4173 * completely swap entries with contiguous swap offsets.
4174 */
4175 order = highest_order(orders);
4176 while (orders) {
4177 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4178 if (can_swapin_thp(vmf, pte + pte_index(addr), 1 << order))
4179 break;
4180 order = next_order(&orders, order);
4181 }
4182
4183 pte_unmap_unlock(pte, ptl);
4184
4185 /* Try allocating the highest of the remaining orders. */
4186 gfp = vma_thp_gfp_mask(vma);
4187 while (orders) {
4188 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4189 folio = vma_alloc_folio(gfp, order, vma, addr);
4190 if (folio) {
4191 if (!mem_cgroup_swapin_charge_folio(folio, vma->vm_mm,
4192 gfp, entry))
4193 return folio;
4194 folio_put(folio);
4195 }
4196 order = next_order(&orders, order);
4197 }
4198
4199fallback:
4200 return __alloc_swap_folio(vmf);
4201}
4202#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
4203static struct folio *alloc_swap_folio(struct vm_fault *vmf)
4204{
4205 return __alloc_swap_folio(vmf);
4206}
4207#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4208
4209static DECLARE_WAIT_QUEUE_HEAD(swapcache_wq);
4210
4211/*
4212 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4213 * but allow concurrent faults), and pte mapped but not yet locked.
4214 * We return with pte unmapped and unlocked.
4215 *
4216 * We return with the mmap_lock locked or unlocked in the same cases
4217 * as does filemap_fault().
4218 */
4219vm_fault_t do_swap_page(struct vm_fault *vmf)
4220{
4221 struct vm_area_struct *vma = vmf->vma;
4222 struct folio *swapcache, *folio = NULL;
4223 DECLARE_WAITQUEUE(wait, current);
4224 struct page *page;
4225 struct swap_info_struct *si = NULL;
4226 rmap_t rmap_flags = RMAP_NONE;
4227 bool need_clear_cache = false;
4228 bool exclusive = false;
4229 swp_entry_t entry;
4230 pte_t pte;
4231 vm_fault_t ret = 0;
4232 void *shadow = NULL;
4233 int nr_pages;
4234 unsigned long page_idx;
4235 unsigned long address;
4236 pte_t *ptep;
4237
4238 if (!pte_unmap_same(vmf))
4239 goto out;
4240
4241 entry = pte_to_swp_entry(vmf->orig_pte);
4242 if (unlikely(non_swap_entry(entry))) {
4243 if (is_migration_entry(entry)) {
4244 migration_entry_wait(vma->vm_mm, vmf->pmd,
4245 vmf->address);
4246 } else if (is_device_exclusive_entry(entry)) {
4247 vmf->page = pfn_swap_entry_to_page(entry);
4248 ret = remove_device_exclusive_entry(vmf);
4249 } else if (is_device_private_entry(entry)) {
4250 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
4251 /*
4252 * migrate_to_ram is not yet ready to operate
4253 * under VMA lock.
4254 */
4255 vma_end_read(vma);
4256 ret = VM_FAULT_RETRY;
4257 goto out;
4258 }
4259
4260 vmf->page = pfn_swap_entry_to_page(entry);
4261 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4262 vmf->address, &vmf->ptl);
4263 if (unlikely(!vmf->pte ||
4264 !pte_same(ptep_get(vmf->pte),
4265 vmf->orig_pte)))
4266 goto unlock;
4267
4268 /*
4269 * Get a page reference while we know the page can't be
4270 * freed.
4271 */
4272 get_page(vmf->page);
4273 pte_unmap_unlock(vmf->pte, vmf->ptl);
4274 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
4275 put_page(vmf->page);
4276 } else if (is_hwpoison_entry(entry)) {
4277 ret = VM_FAULT_HWPOISON;
4278 } else if (is_pte_marker_entry(entry)) {
4279 ret = handle_pte_marker(vmf);
4280 } else {
4281 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
4282 ret = VM_FAULT_SIGBUS;
4283 }
4284 goto out;
4285 }
4286
4287 /* Prevent swapoff from happening to us. */
4288 si = get_swap_device(entry);
4289 if (unlikely(!si))
4290 goto out;
4291
4292 folio = swap_cache_get_folio(entry, vma, vmf->address);
4293 if (folio)
4294 page = folio_file_page(folio, swp_offset(entry));
4295 swapcache = folio;
4296
4297 if (!folio) {
4298 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
4299 __swap_count(entry) == 1) {
4300 /* skip swapcache */
4301 folio = alloc_swap_folio(vmf);
4302 if (folio) {
4303 __folio_set_locked(folio);
4304 __folio_set_swapbacked(folio);
4305
4306 nr_pages = folio_nr_pages(folio);
4307 if (folio_test_large(folio))
4308 entry.val = ALIGN_DOWN(entry.val, nr_pages);
4309 /*
4310 * Prevent parallel swapin from proceeding with
4311 * the cache flag. Otherwise, another thread
4312 * may finish swapin first, free the entry, and
4313 * swapout reusing the same entry. It's
4314 * undetectable as pte_same() returns true due
4315 * to entry reuse.
4316 */
4317 if (swapcache_prepare(entry, nr_pages)) {
4318 /*
4319 * Relax a bit to prevent rapid
4320 * repeated page faults.
4321 */
4322 add_wait_queue(&swapcache_wq, &wait);
4323 schedule_timeout_uninterruptible(1);
4324 remove_wait_queue(&swapcache_wq, &wait);
4325 goto out_page;
4326 }
4327 need_clear_cache = true;
4328
4329 mem_cgroup_swapin_uncharge_swap(entry, nr_pages);
4330
4331 shadow = get_shadow_from_swap_cache(entry);
4332 if (shadow)
4333 workingset_refault(folio, shadow);
4334
4335 folio_add_lru(folio);
4336
4337 /* To provide entry to swap_read_folio() */
4338 folio->swap = entry;
4339 swap_read_folio(folio, NULL);
4340 folio->private = NULL;
4341 }
4342 } else {
4343 folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
4344 vmf);
4345 swapcache = folio;
4346 }
4347
4348 if (!folio) {
4349 /*
4350 * Back out if somebody else faulted in this pte
4351 * while we released the pte lock.
4352 */
4353 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4354 vmf->address, &vmf->ptl);
4355 if (likely(vmf->pte &&
4356 pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4357 ret = VM_FAULT_OOM;
4358 goto unlock;
4359 }
4360
4361 /* Had to read the page from swap area: Major fault */
4362 ret = VM_FAULT_MAJOR;
4363 count_vm_event(PGMAJFAULT);
4364 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
4365 page = folio_file_page(folio, swp_offset(entry));
4366 } else if (PageHWPoison(page)) {
4367 /*
4368 * hwpoisoned dirty swapcache pages are kept for killing
4369 * owner processes (which may be unknown at hwpoison time)
4370 */
4371 ret = VM_FAULT_HWPOISON;
4372 goto out_release;
4373 }
4374
4375 ret |= folio_lock_or_retry(folio, vmf);
4376 if (ret & VM_FAULT_RETRY)
4377 goto out_release;
4378
4379 if (swapcache) {
4380 /*
4381 * Make sure folio_free_swap() or swapoff did not release the
4382 * swapcache from under us. The page pin, and pte_same test
4383 * below, are not enough to exclude that. Even if it is still
4384 * swapcache, we need to check that the page's swap has not
4385 * changed.
4386 */
4387 if (unlikely(!folio_test_swapcache(folio) ||
4388 page_swap_entry(page).val != entry.val))
4389 goto out_page;
4390
4391 /*
4392 * KSM sometimes has to copy on read faults, for example, if
4393 * page->index of !PageKSM() pages would be nonlinear inside the
4394 * anon VMA -- PageKSM() is lost on actual swapout.
4395 */
4396 folio = ksm_might_need_to_copy(folio, vma, vmf->address);
4397 if (unlikely(!folio)) {
4398 ret = VM_FAULT_OOM;
4399 folio = swapcache;
4400 goto out_page;
4401 } else if (unlikely(folio == ERR_PTR(-EHWPOISON))) {
4402 ret = VM_FAULT_HWPOISON;
4403 folio = swapcache;
4404 goto out_page;
4405 }
4406 if (folio != swapcache)
4407 page = folio_page(folio, 0);
4408
4409 /*
4410 * If we want to map a page that's in the swapcache writable, we
4411 * have to detect via the refcount if we're really the exclusive
4412 * owner. Try removing the extra reference from the local LRU
4413 * caches if required.
4414 */
4415 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
4416 !folio_test_ksm(folio) && !folio_test_lru(folio))
4417 lru_add_drain();
4418 }
4419
4420 folio_throttle_swaprate(folio, GFP_KERNEL);
4421
4422 /*
4423 * Back out if somebody else already faulted in this pte.
4424 */
4425 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
4426 &vmf->ptl);
4427 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4428 goto out_nomap;
4429
4430 if (unlikely(!folio_test_uptodate(folio))) {
4431 ret = VM_FAULT_SIGBUS;
4432 goto out_nomap;
4433 }
4434
4435 /* allocated large folios for SWP_SYNCHRONOUS_IO */
4436 if (folio_test_large(folio) && !folio_test_swapcache(folio)) {
4437 unsigned long nr = folio_nr_pages(folio);
4438 unsigned long folio_start = ALIGN_DOWN(vmf->address, nr * PAGE_SIZE);
4439 unsigned long idx = (vmf->address - folio_start) / PAGE_SIZE;
4440 pte_t *folio_ptep = vmf->pte - idx;
4441 pte_t folio_pte = ptep_get(folio_ptep);
4442
4443 if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
4444 swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
4445 goto out_nomap;
4446
4447 page_idx = idx;
4448 address = folio_start;
4449 ptep = folio_ptep;
4450 goto check_folio;
4451 }
4452
4453 nr_pages = 1;
4454 page_idx = 0;
4455 address = vmf->address;
4456 ptep = vmf->pte;
4457 if (folio_test_large(folio) && folio_test_swapcache(folio)) {
4458 int nr = folio_nr_pages(folio);
4459 unsigned long idx = folio_page_idx(folio, page);
4460 unsigned long folio_start = address - idx * PAGE_SIZE;
4461 unsigned long folio_end = folio_start + nr * PAGE_SIZE;
4462 pte_t *folio_ptep;
4463 pte_t folio_pte;
4464
4465 if (unlikely(folio_start < max(address & PMD_MASK, vma->vm_start)))
4466 goto check_folio;
4467 if (unlikely(folio_end > pmd_addr_end(address, vma->vm_end)))
4468 goto check_folio;
4469
4470 folio_ptep = vmf->pte - idx;
4471 folio_pte = ptep_get(folio_ptep);
4472 if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
4473 swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
4474 goto check_folio;
4475
4476 page_idx = idx;
4477 address = folio_start;
4478 ptep = folio_ptep;
4479 nr_pages = nr;
4480 entry = folio->swap;
4481 page = &folio->page;
4482 }
4483
4484check_folio:
4485 /*
4486 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
4487 * must never point at an anonymous page in the swapcache that is
4488 * PG_anon_exclusive. Sanity check that this holds and especially, that
4489 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
4490 * check after taking the PT lock and making sure that nobody
4491 * concurrently faulted in this page and set PG_anon_exclusive.
4492 */
4493 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
4494 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
4495
4496 /*
4497 * Check under PT lock (to protect against concurrent fork() sharing
4498 * the swap entry concurrently) for certainly exclusive pages.
4499 */
4500 if (!folio_test_ksm(folio)) {
4501 exclusive = pte_swp_exclusive(vmf->orig_pte);
4502 if (folio != swapcache) {
4503 /*
4504 * We have a fresh page that is not exposed to the
4505 * swapcache -> certainly exclusive.
4506 */
4507 exclusive = true;
4508 } else if (exclusive && folio_test_writeback(folio) &&
4509 data_race(si->flags & SWP_STABLE_WRITES)) {
4510 /*
4511 * This is tricky: not all swap backends support
4512 * concurrent page modifications while under writeback.
4513 *
4514 * So if we stumble over such a page in the swapcache
4515 * we must not set the page exclusive, otherwise we can
4516 * map it writable without further checks and modify it
4517 * while still under writeback.
4518 *
4519 * For these problematic swap backends, simply drop the
4520 * exclusive marker: this is perfectly fine as we start
4521 * writeback only if we fully unmapped the page and
4522 * there are no unexpected references on the page after
4523 * unmapping succeeded. After fully unmapped, no
4524 * further GUP references (FOLL_GET and FOLL_PIN) can
4525 * appear, so dropping the exclusive marker and mapping
4526 * it only R/O is fine.
4527 */
4528 exclusive = false;
4529 }
4530 }
4531
4532 /*
4533 * Some architectures may have to restore extra metadata to the page
4534 * when reading from swap. This metadata may be indexed by swap entry
4535 * so this must be called before swap_free().
4536 */
4537 arch_swap_restore(folio_swap(entry, folio), folio);
4538
4539 /*
4540 * Remove the swap entry and conditionally try to free up the swapcache.
4541 * We're already holding a reference on the page but haven't mapped it
4542 * yet.
4543 */
4544 swap_free_nr(entry, nr_pages);
4545 if (should_try_to_free_swap(folio, vma, vmf->flags))
4546 folio_free_swap(folio);
4547
4548 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4549 add_mm_counter(vma->vm_mm, MM_SWAPENTS, -nr_pages);
4550 pte = mk_pte(page, vma->vm_page_prot);
4551 if (pte_swp_soft_dirty(vmf->orig_pte))
4552 pte = pte_mksoft_dirty(pte);
4553 if (pte_swp_uffd_wp(vmf->orig_pte))
4554 pte = pte_mkuffd_wp(pte);
4555
4556 /*
4557 * Same logic as in do_wp_page(); however, optimize for pages that are
4558 * certainly not shared either because we just allocated them without
4559 * exposing them to the swapcache or because the swap entry indicates
4560 * exclusivity.
4561 */
4562 if (!folio_test_ksm(folio) &&
4563 (exclusive || folio_ref_count(folio) == 1)) {
4564 if ((vma->vm_flags & VM_WRITE) && !userfaultfd_pte_wp(vma, pte) &&
4565 !pte_needs_soft_dirty_wp(vma, pte)) {
4566 pte = pte_mkwrite(pte, vma);
4567 if (vmf->flags & FAULT_FLAG_WRITE) {
4568 pte = pte_mkdirty(pte);
4569 vmf->flags &= ~FAULT_FLAG_WRITE;
4570 }
4571 }
4572 rmap_flags |= RMAP_EXCLUSIVE;
4573 }
4574 folio_ref_add(folio, nr_pages - 1);
4575 flush_icache_pages(vma, page, nr_pages);
4576 vmf->orig_pte = pte_advance_pfn(pte, page_idx);
4577
4578 /* ksm created a completely new copy */
4579 if (unlikely(folio != swapcache && swapcache)) {
4580 folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
4581 folio_add_lru_vma(folio, vma);
4582 } else if (!folio_test_anon(folio)) {
4583 /*
4584 * We currently only expect small !anon folios which are either
4585 * fully exclusive or fully shared, or new allocated large
4586 * folios which are fully exclusive. If we ever get large
4587 * folios within swapcache here, we have to be careful.
4588 */
4589 VM_WARN_ON_ONCE(folio_test_large(folio) && folio_test_swapcache(folio));
4590 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
4591 folio_add_new_anon_rmap(folio, vma, address, rmap_flags);
4592 } else {
4593 folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address,
4594 rmap_flags);
4595 }
4596
4597 VM_BUG_ON(!folio_test_anon(folio) ||
4598 (pte_write(pte) && !PageAnonExclusive(page)));
4599 set_ptes(vma->vm_mm, address, ptep, pte, nr_pages);
4600 arch_do_swap_page_nr(vma->vm_mm, vma, address,
4601 pte, pte, nr_pages);
4602
4603 folio_unlock(folio);
4604 if (folio != swapcache && swapcache) {
4605 /*
4606 * Hold the lock to avoid the swap entry to be reused
4607 * until we take the PT lock for the pte_same() check
4608 * (to avoid false positives from pte_same). For
4609 * further safety release the lock after the swap_free
4610 * so that the swap count won't change under a
4611 * parallel locked swapcache.
4612 */
4613 folio_unlock(swapcache);
4614 folio_put(swapcache);
4615 }
4616
4617 if (vmf->flags & FAULT_FLAG_WRITE) {
4618 ret |= do_wp_page(vmf);
4619 if (ret & VM_FAULT_ERROR)
4620 ret &= VM_FAULT_ERROR;
4621 goto out;
4622 }
4623
4624 /* No need to invalidate - it was non-present before */
4625 update_mmu_cache_range(vmf, vma, address, ptep, nr_pages);
4626unlock:
4627 if (vmf->pte)
4628 pte_unmap_unlock(vmf->pte, vmf->ptl);
4629out:
4630 /* Clear the swap cache pin for direct swapin after PTL unlock */
4631 if (need_clear_cache) {
4632 swapcache_clear(si, entry, nr_pages);
4633 if (waitqueue_active(&swapcache_wq))
4634 wake_up(&swapcache_wq);
4635 }
4636 if (si)
4637 put_swap_device(si);
4638 return ret;
4639out_nomap:
4640 if (vmf->pte)
4641 pte_unmap_unlock(vmf->pte, vmf->ptl);
4642out_page:
4643 folio_unlock(folio);
4644out_release:
4645 folio_put(folio);
4646 if (folio != swapcache && swapcache) {
4647 folio_unlock(swapcache);
4648 folio_put(swapcache);
4649 }
4650 if (need_clear_cache) {
4651 swapcache_clear(si, entry, nr_pages);
4652 if (waitqueue_active(&swapcache_wq))
4653 wake_up(&swapcache_wq);
4654 }
4655 if (si)
4656 put_swap_device(si);
4657 return ret;
4658}
4659
4660static bool pte_range_none(pte_t *pte, int nr_pages)
4661{
4662 int i;
4663
4664 for (i = 0; i < nr_pages; i++) {
4665 if (!pte_none(ptep_get_lockless(pte + i)))
4666 return false;
4667 }
4668
4669 return true;
4670}
4671
4672static struct folio *alloc_anon_folio(struct vm_fault *vmf)
4673{
4674 struct vm_area_struct *vma = vmf->vma;
4675#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4676 unsigned long orders;
4677 struct folio *folio;
4678 unsigned long addr;
4679 pte_t *pte;
4680 gfp_t gfp;
4681 int order;
4682
4683 /*
4684 * If uffd is active for the vma we need per-page fault fidelity to
4685 * maintain the uffd semantics.
4686 */
4687 if (unlikely(userfaultfd_armed(vma)))
4688 goto fallback;
4689
4690 /*
4691 * Get a list of all the (large) orders below PMD_ORDER that are enabled
4692 * for this vma. Then filter out the orders that can't be allocated over
4693 * the faulting address and still be fully contained in the vma.
4694 */
4695 orders = thp_vma_allowable_orders(vma, vma->vm_flags,
4696 TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
4697 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
4698
4699 if (!orders)
4700 goto fallback;
4701
4702 pte = pte_offset_map(vmf->pmd, vmf->address & PMD_MASK);
4703 if (!pte)
4704 return ERR_PTR(-EAGAIN);
4705
4706 /*
4707 * Find the highest order where the aligned range is completely
4708 * pte_none(). Note that all remaining orders will be completely
4709 * pte_none().
4710 */
4711 order = highest_order(orders);
4712 while (orders) {
4713 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4714 if (pte_range_none(pte + pte_index(addr), 1 << order))
4715 break;
4716 order = next_order(&orders, order);
4717 }
4718
4719 pte_unmap(pte);
4720
4721 if (!orders)
4722 goto fallback;
4723
4724 /* Try allocating the highest of the remaining orders. */
4725 gfp = vma_thp_gfp_mask(vma);
4726 while (orders) {
4727 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4728 folio = vma_alloc_folio(gfp, order, vma, addr);
4729 if (folio) {
4730 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) {
4731 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
4732 folio_put(folio);
4733 goto next;
4734 }
4735 folio_throttle_swaprate(folio, gfp);
4736 /*
4737 * When a folio is not zeroed during allocation
4738 * (__GFP_ZERO not used) or user folios require special
4739 * handling, folio_zero_user() is used to make sure
4740 * that the page corresponding to the faulting address
4741 * will be hot in the cache after zeroing.
4742 */
4743 if (user_alloc_needs_zeroing())
4744 folio_zero_user(folio, vmf->address);
4745 return folio;
4746 }
4747next:
4748 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK);
4749 order = next_order(&orders, order);
4750 }
4751
4752fallback:
4753#endif
4754 return folio_prealloc(vma->vm_mm, vma, vmf->address, true);
4755}
4756
4757/*
4758 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4759 * but allow concurrent faults), and pte mapped but not yet locked.
4760 * We return with mmap_lock still held, but pte unmapped and unlocked.
4761 */
4762static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
4763{
4764 struct vm_area_struct *vma = vmf->vma;
4765 unsigned long addr = vmf->address;
4766 struct folio *folio;
4767 vm_fault_t ret = 0;
4768 int nr_pages = 1;
4769 pte_t entry;
4770
4771 /* File mapping without ->vm_ops ? */
4772 if (vma->vm_flags & VM_SHARED)
4773 return VM_FAULT_SIGBUS;
4774
4775 /*
4776 * Use pte_alloc() instead of pte_alloc_map(), so that OOM can
4777 * be distinguished from a transient failure of pte_offset_map().
4778 */
4779 if (pte_alloc(vma->vm_mm, vmf->pmd))
4780 return VM_FAULT_OOM;
4781
4782 /* Use the zero-page for reads */
4783 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
4784 !mm_forbids_zeropage(vma->vm_mm)) {
4785 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
4786 vma->vm_page_prot));
4787 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4788 vmf->address, &vmf->ptl);
4789 if (!vmf->pte)
4790 goto unlock;
4791 if (vmf_pte_changed(vmf)) {
4792 update_mmu_tlb(vma, vmf->address, vmf->pte);
4793 goto unlock;
4794 }
4795 ret = check_stable_address_space(vma->vm_mm);
4796 if (ret)
4797 goto unlock;
4798 /* Deliver the page fault to userland, check inside PT lock */
4799 if (userfaultfd_missing(vma)) {
4800 pte_unmap_unlock(vmf->pte, vmf->ptl);
4801 return handle_userfault(vmf, VM_UFFD_MISSING);
4802 }
4803 goto setpte;
4804 }
4805
4806 /* Allocate our own private page. */
4807 ret = vmf_anon_prepare(vmf);
4808 if (ret)
4809 return ret;
4810 /* Returns NULL on OOM or ERR_PTR(-EAGAIN) if we must retry the fault */
4811 folio = alloc_anon_folio(vmf);
4812 if (IS_ERR(folio))
4813 return 0;
4814 if (!folio)
4815 goto oom;
4816
4817 nr_pages = folio_nr_pages(folio);
4818 addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE);
4819
4820 /*
4821 * The memory barrier inside __folio_mark_uptodate makes sure that
4822 * preceding stores to the page contents become visible before
4823 * the set_pte_at() write.
4824 */
4825 __folio_mark_uptodate(folio);
4826
4827 entry = mk_pte(&folio->page, vma->vm_page_prot);
4828 entry = pte_sw_mkyoung(entry);
4829 if (vma->vm_flags & VM_WRITE)
4830 entry = pte_mkwrite(pte_mkdirty(entry), vma);
4831
4832 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
4833 if (!vmf->pte)
4834 goto release;
4835 if (nr_pages == 1 && vmf_pte_changed(vmf)) {
4836 update_mmu_tlb(vma, addr, vmf->pte);
4837 goto release;
4838 } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) {
4839 update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages);
4840 goto release;
4841 }
4842
4843 ret = check_stable_address_space(vma->vm_mm);
4844 if (ret)
4845 goto release;
4846
4847 /* Deliver the page fault to userland, check inside PT lock */
4848 if (userfaultfd_missing(vma)) {
4849 pte_unmap_unlock(vmf->pte, vmf->ptl);
4850 folio_put(folio);
4851 return handle_userfault(vmf, VM_UFFD_MISSING);
4852 }
4853
4854 folio_ref_add(folio, nr_pages - 1);
4855 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4856 count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_FAULT_ALLOC);
4857 folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
4858 folio_add_lru_vma(folio, vma);
4859setpte:
4860 if (vmf_orig_pte_uffd_wp(vmf))
4861 entry = pte_mkuffd_wp(entry);
4862 set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr_pages);
4863
4864 /* No need to invalidate - it was non-present before */
4865 update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr_pages);
4866unlock:
4867 if (vmf->pte)
4868 pte_unmap_unlock(vmf->pte, vmf->ptl);
4869 return ret;
4870release:
4871 folio_put(folio);
4872 goto unlock;
4873oom:
4874 return VM_FAULT_OOM;
4875}
4876
4877/*
4878 * The mmap_lock must have been held on entry, and may have been
4879 * released depending on flags and vma->vm_ops->fault() return value.
4880 * See filemap_fault() and __lock_page_retry().
4881 */
4882static vm_fault_t __do_fault(struct vm_fault *vmf)
4883{
4884 struct vm_area_struct *vma = vmf->vma;
4885 struct folio *folio;
4886 vm_fault_t ret;
4887
4888 /*
4889 * Preallocate pte before we take page_lock because this might lead to
4890 * deadlocks for memcg reclaim which waits for pages under writeback:
4891 * lock_page(A)
4892 * SetPageWriteback(A)
4893 * unlock_page(A)
4894 * lock_page(B)
4895 * lock_page(B)
4896 * pte_alloc_one
4897 * shrink_folio_list
4898 * wait_on_page_writeback(A)
4899 * SetPageWriteback(B)
4900 * unlock_page(B)
4901 * # flush A, B to clear the writeback
4902 */
4903 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
4904 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4905 if (!vmf->prealloc_pte)
4906 return VM_FAULT_OOM;
4907 }
4908
4909 ret = vma->vm_ops->fault(vmf);
4910 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
4911 VM_FAULT_DONE_COW)))
4912 return ret;
4913
4914 folio = page_folio(vmf->page);
4915 if (unlikely(PageHWPoison(vmf->page))) {
4916 vm_fault_t poisonret = VM_FAULT_HWPOISON;
4917 if (ret & VM_FAULT_LOCKED) {
4918 if (page_mapped(vmf->page))
4919 unmap_mapping_folio(folio);
4920 /* Retry if a clean folio was removed from the cache. */
4921 if (mapping_evict_folio(folio->mapping, folio))
4922 poisonret = VM_FAULT_NOPAGE;
4923 folio_unlock(folio);
4924 }
4925 folio_put(folio);
4926 vmf->page = NULL;
4927 return poisonret;
4928 }
4929
4930 if (unlikely(!(ret & VM_FAULT_LOCKED)))
4931 folio_lock(folio);
4932 else
4933 VM_BUG_ON_PAGE(!folio_test_locked(folio), vmf->page);
4934
4935 return ret;
4936}
4937
4938#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4939static void deposit_prealloc_pte(struct vm_fault *vmf)
4940{
4941 struct vm_area_struct *vma = vmf->vma;
4942
4943 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
4944 /*
4945 * We are going to consume the prealloc table,
4946 * count that as nr_ptes.
4947 */
4948 mm_inc_nr_ptes(vma->vm_mm);
4949 vmf->prealloc_pte = NULL;
4950}
4951
4952vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4953{
4954 struct folio *folio = page_folio(page);
4955 struct vm_area_struct *vma = vmf->vma;
4956 bool write = vmf->flags & FAULT_FLAG_WRITE;
4957 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
4958 pmd_t entry;
4959 vm_fault_t ret = VM_FAULT_FALLBACK;
4960
4961 /*
4962 * It is too late to allocate a small folio, we already have a large
4963 * folio in the pagecache: especially s390 KVM cannot tolerate any
4964 * PMD mappings, but PTE-mapped THP are fine. So let's simply refuse any
4965 * PMD mappings if THPs are disabled.
4966 */
4967 if (thp_disabled_by_hw() || vma_thp_disabled(vma, vma->vm_flags))
4968 return ret;
4969
4970 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
4971 return ret;
4972
4973 if (folio_order(folio) != HPAGE_PMD_ORDER)
4974 return ret;
4975 page = &folio->page;
4976
4977 /*
4978 * Just backoff if any subpage of a THP is corrupted otherwise
4979 * the corrupted page may mapped by PMD silently to escape the
4980 * check. This kind of THP just can be PTE mapped. Access to
4981 * the corrupted subpage should trigger SIGBUS as expected.
4982 */
4983 if (unlikely(folio_test_has_hwpoisoned(folio)))
4984 return ret;
4985
4986 /*
4987 * Archs like ppc64 need additional space to store information
4988 * related to pte entry. Use the preallocated table for that.
4989 */
4990 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
4991 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4992 if (!vmf->prealloc_pte)
4993 return VM_FAULT_OOM;
4994 }
4995
4996 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4997 if (unlikely(!pmd_none(*vmf->pmd)))
4998 goto out;
4999
5000 flush_icache_pages(vma, page, HPAGE_PMD_NR);
5001
5002 entry = mk_huge_pmd(page, vma->vm_page_prot);
5003 if (write)
5004 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
5005
5006 add_mm_counter(vma->vm_mm, mm_counter_file(folio), HPAGE_PMD_NR);
5007 folio_add_file_rmap_pmd(folio, page, vma);
5008
5009 /*
5010 * deposit and withdraw with pmd lock held
5011 */
5012 if (arch_needs_pgtable_deposit())
5013 deposit_prealloc_pte(vmf);
5014
5015 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
5016
5017 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
5018
5019 /* fault is handled */
5020 ret = 0;
5021 count_vm_event(THP_FILE_MAPPED);
5022out:
5023 spin_unlock(vmf->ptl);
5024 return ret;
5025}
5026#else
5027vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
5028{
5029 return VM_FAULT_FALLBACK;
5030}
5031#endif
5032
5033/**
5034 * set_pte_range - Set a range of PTEs to point to pages in a folio.
5035 * @vmf: Fault decription.
5036 * @folio: The folio that contains @page.
5037 * @page: The first page to create a PTE for.
5038 * @nr: The number of PTEs to create.
5039 * @addr: The first address to create a PTE for.
5040 */
5041void set_pte_range(struct vm_fault *vmf, struct folio *folio,
5042 struct page *page, unsigned int nr, unsigned long addr)
5043{
5044 struct vm_area_struct *vma = vmf->vma;
5045 bool write = vmf->flags & FAULT_FLAG_WRITE;
5046 bool prefault = !in_range(vmf->address, addr, nr * PAGE_SIZE);
5047 pte_t entry;
5048
5049 flush_icache_pages(vma, page, nr);
5050 entry = mk_pte(page, vma->vm_page_prot);
5051
5052 if (prefault && arch_wants_old_prefaulted_pte())
5053 entry = pte_mkold(entry);
5054 else
5055 entry = pte_sw_mkyoung(entry);
5056
5057 if (write)
5058 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
5059 if (unlikely(vmf_orig_pte_uffd_wp(vmf)))
5060 entry = pte_mkuffd_wp(entry);
5061 /* copy-on-write page */
5062 if (write && !(vma->vm_flags & VM_SHARED)) {
5063 VM_BUG_ON_FOLIO(nr != 1, folio);
5064 folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
5065 folio_add_lru_vma(folio, vma);
5066 } else {
5067 folio_add_file_rmap_ptes(folio, page, nr, vma);
5068 }
5069 set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr);
5070
5071 /* no need to invalidate: a not-present page won't be cached */
5072 update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr);
5073}
5074
5075static bool vmf_pte_changed(struct vm_fault *vmf)
5076{
5077 if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)
5078 return !pte_same(ptep_get(vmf->pte), vmf->orig_pte);
5079
5080 return !pte_none(ptep_get(vmf->pte));
5081}
5082
5083/**
5084 * finish_fault - finish page fault once we have prepared the page to fault
5085 *
5086 * @vmf: structure describing the fault
5087 *
5088 * This function handles all that is needed to finish a page fault once the
5089 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
5090 * given page, adds reverse page mapping, handles memcg charges and LRU
5091 * addition.
5092 *
5093 * The function expects the page to be locked and on success it consumes a
5094 * reference of a page being mapped (for the PTE which maps it).
5095 *
5096 * Return: %0 on success, %VM_FAULT_ code in case of error.
5097 */
5098vm_fault_t finish_fault(struct vm_fault *vmf)
5099{
5100 struct vm_area_struct *vma = vmf->vma;
5101 struct page *page;
5102 struct folio *folio;
5103 vm_fault_t ret;
5104 bool is_cow = (vmf->flags & FAULT_FLAG_WRITE) &&
5105 !(vma->vm_flags & VM_SHARED);
5106 int type, nr_pages;
5107 unsigned long addr;
5108 bool needs_fallback = false;
5109
5110fallback:
5111 addr = vmf->address;
5112
5113 /* Did we COW the page? */
5114 if (is_cow)
5115 page = vmf->cow_page;
5116 else
5117 page = vmf->page;
5118
5119 /*
5120 * check even for read faults because we might have lost our CoWed
5121 * page
5122 */
5123 if (!(vma->vm_flags & VM_SHARED)) {
5124 ret = check_stable_address_space(vma->vm_mm);
5125 if (ret)
5126 return ret;
5127 }
5128
5129 if (pmd_none(*vmf->pmd)) {
5130 if (PageTransCompound(page)) {
5131 ret = do_set_pmd(vmf, page);
5132 if (ret != VM_FAULT_FALLBACK)
5133 return ret;
5134 }
5135
5136 if (vmf->prealloc_pte)
5137 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
5138 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
5139 return VM_FAULT_OOM;
5140 }
5141
5142 folio = page_folio(page);
5143 nr_pages = folio_nr_pages(folio);
5144
5145 /*
5146 * Using per-page fault to maintain the uffd semantics, and same
5147 * approach also applies to non-anonymous-shmem faults to avoid
5148 * inflating the RSS of the process.
5149 */
5150 if (!vma_is_anon_shmem(vma) || unlikely(userfaultfd_armed(vma)) ||
5151 unlikely(needs_fallback)) {
5152 nr_pages = 1;
5153 } else if (nr_pages > 1) {
5154 pgoff_t idx = folio_page_idx(folio, page);
5155 /* The page offset of vmf->address within the VMA. */
5156 pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff;
5157 /* The index of the entry in the pagetable for fault page. */
5158 pgoff_t pte_off = pte_index(vmf->address);
5159
5160 /*
5161 * Fallback to per-page fault in case the folio size in page
5162 * cache beyond the VMA limits and PMD pagetable limits.
5163 */
5164 if (unlikely(vma_off < idx ||
5165 vma_off + (nr_pages - idx) > vma_pages(vma) ||
5166 pte_off < idx ||
5167 pte_off + (nr_pages - idx) > PTRS_PER_PTE)) {
5168 nr_pages = 1;
5169 } else {
5170 /* Now we can set mappings for the whole large folio. */
5171 addr = vmf->address - idx * PAGE_SIZE;
5172 page = &folio->page;
5173 }
5174 }
5175
5176 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
5177 addr, &vmf->ptl);
5178 if (!vmf->pte)
5179 return VM_FAULT_NOPAGE;
5180
5181 /* Re-check under ptl */
5182 if (nr_pages == 1 && unlikely(vmf_pte_changed(vmf))) {
5183 update_mmu_tlb(vma, addr, vmf->pte);
5184 ret = VM_FAULT_NOPAGE;
5185 goto unlock;
5186 } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) {
5187 needs_fallback = true;
5188 pte_unmap_unlock(vmf->pte, vmf->ptl);
5189 goto fallback;
5190 }
5191
5192 folio_ref_add(folio, nr_pages - 1);
5193 set_pte_range(vmf, folio, page, nr_pages, addr);
5194 type = is_cow ? MM_ANONPAGES : mm_counter_file(folio);
5195 add_mm_counter(vma->vm_mm, type, nr_pages);
5196 ret = 0;
5197
5198unlock:
5199 pte_unmap_unlock(vmf->pte, vmf->ptl);
5200 return ret;
5201}
5202
5203static unsigned long fault_around_pages __read_mostly =
5204 65536 >> PAGE_SHIFT;
5205
5206#ifdef CONFIG_DEBUG_FS
5207static int fault_around_bytes_get(void *data, u64 *val)
5208{
5209 *val = fault_around_pages << PAGE_SHIFT;
5210 return 0;
5211}
5212
5213/*
5214 * fault_around_bytes must be rounded down to the nearest page order as it's
5215 * what do_fault_around() expects to see.
5216 */
5217static int fault_around_bytes_set(void *data, u64 val)
5218{
5219 if (val / PAGE_SIZE > PTRS_PER_PTE)
5220 return -EINVAL;
5221
5222 /*
5223 * The minimum value is 1 page, however this results in no fault-around
5224 * at all. See should_fault_around().
5225 */
5226 val = max(val, PAGE_SIZE);
5227 fault_around_pages = rounddown_pow_of_two(val) >> PAGE_SHIFT;
5228
5229 return 0;
5230}
5231DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
5232 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
5233
5234static int __init fault_around_debugfs(void)
5235{
5236 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
5237 &fault_around_bytes_fops);
5238 return 0;
5239}
5240late_initcall(fault_around_debugfs);
5241#endif
5242
5243/*
5244 * do_fault_around() tries to map few pages around the fault address. The hope
5245 * is that the pages will be needed soon and this will lower the number of
5246 * faults to handle.
5247 *
5248 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
5249 * not ready to be mapped: not up-to-date, locked, etc.
5250 *
5251 * This function doesn't cross VMA or page table boundaries, in order to call
5252 * map_pages() and acquire a PTE lock only once.
5253 *
5254 * fault_around_pages defines how many pages we'll try to map.
5255 * do_fault_around() expects it to be set to a power of two less than or equal
5256 * to PTRS_PER_PTE.
5257 *
5258 * The virtual address of the area that we map is naturally aligned to
5259 * fault_around_pages * PAGE_SIZE rounded down to the machine page size
5260 * (and therefore to page order). This way it's easier to guarantee
5261 * that we don't cross page table boundaries.
5262 */
5263static vm_fault_t do_fault_around(struct vm_fault *vmf)
5264{
5265 pgoff_t nr_pages = READ_ONCE(fault_around_pages);
5266 pgoff_t pte_off = pte_index(vmf->address);
5267 /* The page offset of vmf->address within the VMA. */
5268 pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff;
5269 pgoff_t from_pte, to_pte;
5270 vm_fault_t ret;
5271
5272 /* The PTE offset of the start address, clamped to the VMA. */
5273 from_pte = max(ALIGN_DOWN(pte_off, nr_pages),
5274 pte_off - min(pte_off, vma_off));
5275
5276 /* The PTE offset of the end address, clamped to the VMA and PTE. */
5277 to_pte = min3(from_pte + nr_pages, (pgoff_t)PTRS_PER_PTE,
5278 pte_off + vma_pages(vmf->vma) - vma_off) - 1;
5279
5280 if (pmd_none(*vmf->pmd)) {
5281 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
5282 if (!vmf->prealloc_pte)
5283 return VM_FAULT_OOM;
5284 }
5285
5286 rcu_read_lock();
5287 ret = vmf->vma->vm_ops->map_pages(vmf,
5288 vmf->pgoff + from_pte - pte_off,
5289 vmf->pgoff + to_pte - pte_off);
5290 rcu_read_unlock();
5291
5292 return ret;
5293}
5294
5295/* Return true if we should do read fault-around, false otherwise */
5296static inline bool should_fault_around(struct vm_fault *vmf)
5297{
5298 /* No ->map_pages? No way to fault around... */
5299 if (!vmf->vma->vm_ops->map_pages)
5300 return false;
5301
5302 if (uffd_disable_fault_around(vmf->vma))
5303 return false;
5304
5305 /* A single page implies no faulting 'around' at all. */
5306 return fault_around_pages > 1;
5307}
5308
5309static vm_fault_t do_read_fault(struct vm_fault *vmf)
5310{
5311 vm_fault_t ret = 0;
5312 struct folio *folio;
5313
5314 /*
5315 * Let's call ->map_pages() first and use ->fault() as fallback
5316 * if page by the offset is not ready to be mapped (cold cache or
5317 * something).
5318 */
5319 if (should_fault_around(vmf)) {
5320 ret = do_fault_around(vmf);
5321 if (ret)
5322 return ret;
5323 }
5324
5325 ret = vmf_can_call_fault(vmf);
5326 if (ret)
5327 return ret;
5328
5329 ret = __do_fault(vmf);
5330 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5331 return ret;
5332
5333 ret |= finish_fault(vmf);
5334 folio = page_folio(vmf->page);
5335 folio_unlock(folio);
5336 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5337 folio_put(folio);
5338 return ret;
5339}
5340
5341static vm_fault_t do_cow_fault(struct vm_fault *vmf)
5342{
5343 struct vm_area_struct *vma = vmf->vma;
5344 struct folio *folio;
5345 vm_fault_t ret;
5346
5347 ret = vmf_can_call_fault(vmf);
5348 if (!ret)
5349 ret = vmf_anon_prepare(vmf);
5350 if (ret)
5351 return ret;
5352
5353 folio = folio_prealloc(vma->vm_mm, vma, vmf->address, false);
5354 if (!folio)
5355 return VM_FAULT_OOM;
5356
5357 vmf->cow_page = &folio->page;
5358
5359 ret = __do_fault(vmf);
5360 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5361 goto uncharge_out;
5362 if (ret & VM_FAULT_DONE_COW)
5363 return ret;
5364
5365 if (copy_mc_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma)) {
5366 ret = VM_FAULT_HWPOISON;
5367 goto unlock;
5368 }
5369 __folio_mark_uptodate(folio);
5370
5371 ret |= finish_fault(vmf);
5372unlock:
5373 unlock_page(vmf->page);
5374 put_page(vmf->page);
5375 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5376 goto uncharge_out;
5377 return ret;
5378uncharge_out:
5379 folio_put(folio);
5380 return ret;
5381}
5382
5383static vm_fault_t do_shared_fault(struct vm_fault *vmf)
5384{
5385 struct vm_area_struct *vma = vmf->vma;
5386 vm_fault_t ret, tmp;
5387 struct folio *folio;
5388
5389 ret = vmf_can_call_fault(vmf);
5390 if (ret)
5391 return ret;
5392
5393 ret = __do_fault(vmf);
5394 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5395 return ret;
5396
5397 folio = page_folio(vmf->page);
5398
5399 /*
5400 * Check if the backing address space wants to know that the page is
5401 * about to become writable
5402 */
5403 if (vma->vm_ops->page_mkwrite) {
5404 folio_unlock(folio);
5405 tmp = do_page_mkwrite(vmf, folio);
5406 if (unlikely(!tmp ||
5407 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
5408 folio_put(folio);
5409 return tmp;
5410 }
5411 }
5412
5413 ret |= finish_fault(vmf);
5414 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
5415 VM_FAULT_RETRY))) {
5416 folio_unlock(folio);
5417 folio_put(folio);
5418 return ret;
5419 }
5420
5421 ret |= fault_dirty_shared_page(vmf);
5422 return ret;
5423}
5424
5425/*
5426 * We enter with non-exclusive mmap_lock (to exclude vma changes,
5427 * but allow concurrent faults).
5428 * The mmap_lock may have been released depending on flags and our
5429 * return value. See filemap_fault() and __folio_lock_or_retry().
5430 * If mmap_lock is released, vma may become invalid (for example
5431 * by other thread calling munmap()).
5432 */
5433static vm_fault_t do_fault(struct vm_fault *vmf)
5434{
5435 struct vm_area_struct *vma = vmf->vma;
5436 struct mm_struct *vm_mm = vma->vm_mm;
5437 vm_fault_t ret;
5438
5439 /*
5440 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
5441 */
5442 if (!vma->vm_ops->fault) {
5443 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
5444 vmf->address, &vmf->ptl);
5445 if (unlikely(!vmf->pte))
5446 ret = VM_FAULT_SIGBUS;
5447 else {
5448 /*
5449 * Make sure this is not a temporary clearing of pte
5450 * by holding ptl and checking again. A R/M/W update
5451 * of pte involves: take ptl, clearing the pte so that
5452 * we don't have concurrent modification by hardware
5453 * followed by an update.
5454 */
5455 if (unlikely(pte_none(ptep_get(vmf->pte))))
5456 ret = VM_FAULT_SIGBUS;
5457 else
5458 ret = VM_FAULT_NOPAGE;
5459
5460 pte_unmap_unlock(vmf->pte, vmf->ptl);
5461 }
5462 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
5463 ret = do_read_fault(vmf);
5464 else if (!(vma->vm_flags & VM_SHARED))
5465 ret = do_cow_fault(vmf);
5466 else
5467 ret = do_shared_fault(vmf);
5468
5469 /* preallocated pagetable is unused: free it */
5470 if (vmf->prealloc_pte) {
5471 pte_free(vm_mm, vmf->prealloc_pte);
5472 vmf->prealloc_pte = NULL;
5473 }
5474 return ret;
5475}
5476
5477int numa_migrate_check(struct folio *folio, struct vm_fault *vmf,
5478 unsigned long addr, int *flags,
5479 bool writable, int *last_cpupid)
5480{
5481 struct vm_area_struct *vma = vmf->vma;
5482
5483 /*
5484 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
5485 * much anyway since they can be in shared cache state. This misses
5486 * the case where a mapping is writable but the process never writes
5487 * to it but pte_write gets cleared during protection updates and
5488 * pte_dirty has unpredictable behaviour between PTE scan updates,
5489 * background writeback, dirty balancing and application behaviour.
5490 */
5491 if (!writable)
5492 *flags |= TNF_NO_GROUP;
5493
5494 /*
5495 * Flag if the folio is shared between multiple address spaces. This
5496 * is later used when determining whether to group tasks together
5497 */
5498 if (folio_likely_mapped_shared(folio) && (vma->vm_flags & VM_SHARED))
5499 *flags |= TNF_SHARED;
5500 /*
5501 * For memory tiering mode, cpupid of slow memory page is used
5502 * to record page access time. So use default value.
5503 */
5504 if (folio_use_access_time(folio))
5505 *last_cpupid = (-1 & LAST_CPUPID_MASK);
5506 else
5507 *last_cpupid = folio_last_cpupid(folio);
5508
5509 /* Record the current PID acceesing VMA */
5510 vma_set_access_pid_bit(vma);
5511
5512 count_vm_numa_event(NUMA_HINT_FAULTS);
5513#ifdef CONFIG_NUMA_BALANCING
5514 count_memcg_folio_events(folio, NUMA_HINT_FAULTS, 1);
5515#endif
5516 if (folio_nid(folio) == numa_node_id()) {
5517 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
5518 *flags |= TNF_FAULT_LOCAL;
5519 }
5520
5521 return mpol_misplaced(folio, vmf, addr);
5522}
5523
5524static void numa_rebuild_single_mapping(struct vm_fault *vmf, struct vm_area_struct *vma,
5525 unsigned long fault_addr, pte_t *fault_pte,
5526 bool writable)
5527{
5528 pte_t pte, old_pte;
5529
5530 old_pte = ptep_modify_prot_start(vma, fault_addr, fault_pte);
5531 pte = pte_modify(old_pte, vma->vm_page_prot);
5532 pte = pte_mkyoung(pte);
5533 if (writable)
5534 pte = pte_mkwrite(pte, vma);
5535 ptep_modify_prot_commit(vma, fault_addr, fault_pte, old_pte, pte);
5536 update_mmu_cache_range(vmf, vma, fault_addr, fault_pte, 1);
5537}
5538
5539static void numa_rebuild_large_mapping(struct vm_fault *vmf, struct vm_area_struct *vma,
5540 struct folio *folio, pte_t fault_pte,
5541 bool ignore_writable, bool pte_write_upgrade)
5542{
5543 int nr = pte_pfn(fault_pte) - folio_pfn(folio);
5544 unsigned long start, end, addr = vmf->address;
5545 unsigned long addr_start = addr - (nr << PAGE_SHIFT);
5546 unsigned long pt_start = ALIGN_DOWN(addr, PMD_SIZE);
5547 pte_t *start_ptep;
5548
5549 /* Stay within the VMA and within the page table. */
5550 start = max3(addr_start, pt_start, vma->vm_start);
5551 end = min3(addr_start + folio_size(folio), pt_start + PMD_SIZE,
5552 vma->vm_end);
5553 start_ptep = vmf->pte - ((addr - start) >> PAGE_SHIFT);
5554
5555 /* Restore all PTEs' mapping of the large folio */
5556 for (addr = start; addr != end; start_ptep++, addr += PAGE_SIZE) {
5557 pte_t ptent = ptep_get(start_ptep);
5558 bool writable = false;
5559
5560 if (!pte_present(ptent) || !pte_protnone(ptent))
5561 continue;
5562
5563 if (pfn_folio(pte_pfn(ptent)) != folio)
5564 continue;
5565
5566 if (!ignore_writable) {
5567 ptent = pte_modify(ptent, vma->vm_page_prot);
5568 writable = pte_write(ptent);
5569 if (!writable && pte_write_upgrade &&
5570 can_change_pte_writable(vma, addr, ptent))
5571 writable = true;
5572 }
5573
5574 numa_rebuild_single_mapping(vmf, vma, addr, start_ptep, writable);
5575 }
5576}
5577
5578static vm_fault_t do_numa_page(struct vm_fault *vmf)
5579{
5580 struct vm_area_struct *vma = vmf->vma;
5581 struct folio *folio = NULL;
5582 int nid = NUMA_NO_NODE;
5583 bool writable = false, ignore_writable = false;
5584 bool pte_write_upgrade = vma_wants_manual_pte_write_upgrade(vma);
5585 int last_cpupid;
5586 int target_nid;
5587 pte_t pte, old_pte;
5588 int flags = 0, nr_pages;
5589
5590 /*
5591 * The pte cannot be used safely until we verify, while holding the page
5592 * table lock, that its contents have not changed during fault handling.
5593 */
5594 spin_lock(vmf->ptl);
5595 /* Read the live PTE from the page tables: */
5596 old_pte = ptep_get(vmf->pte);
5597
5598 if (unlikely(!pte_same(old_pte, vmf->orig_pte))) {
5599 pte_unmap_unlock(vmf->pte, vmf->ptl);
5600 return 0;
5601 }
5602
5603 pte = pte_modify(old_pte, vma->vm_page_prot);
5604
5605 /*
5606 * Detect now whether the PTE could be writable; this information
5607 * is only valid while holding the PT lock.
5608 */
5609 writable = pte_write(pte);
5610 if (!writable && pte_write_upgrade &&
5611 can_change_pte_writable(vma, vmf->address, pte))
5612 writable = true;
5613
5614 folio = vm_normal_folio(vma, vmf->address, pte);
5615 if (!folio || folio_is_zone_device(folio))
5616 goto out_map;
5617
5618 nid = folio_nid(folio);
5619 nr_pages = folio_nr_pages(folio);
5620
5621 target_nid = numa_migrate_check(folio, vmf, vmf->address, &flags,
5622 writable, &last_cpupid);
5623 if (target_nid == NUMA_NO_NODE)
5624 goto out_map;
5625 if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) {
5626 flags |= TNF_MIGRATE_FAIL;
5627 goto out_map;
5628 }
5629 /* The folio is isolated and isolation code holds a folio reference. */
5630 pte_unmap_unlock(vmf->pte, vmf->ptl);
5631 writable = false;
5632 ignore_writable = true;
5633
5634 /* Migrate to the requested node */
5635 if (!migrate_misplaced_folio(folio, vma, target_nid)) {
5636 nid = target_nid;
5637 flags |= TNF_MIGRATED;
5638 task_numa_fault(last_cpupid, nid, nr_pages, flags);
5639 return 0;
5640 }
5641
5642 flags |= TNF_MIGRATE_FAIL;
5643 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
5644 vmf->address, &vmf->ptl);
5645 if (unlikely(!vmf->pte))
5646 return 0;
5647 if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
5648 pte_unmap_unlock(vmf->pte, vmf->ptl);
5649 return 0;
5650 }
5651out_map:
5652 /*
5653 * Make it present again, depending on how arch implements
5654 * non-accessible ptes, some can allow access by kernel mode.
5655 */
5656 if (folio && folio_test_large(folio))
5657 numa_rebuild_large_mapping(vmf, vma, folio, pte, ignore_writable,
5658 pte_write_upgrade);
5659 else
5660 numa_rebuild_single_mapping(vmf, vma, vmf->address, vmf->pte,
5661 writable);
5662 pte_unmap_unlock(vmf->pte, vmf->ptl);
5663
5664 if (nid != NUMA_NO_NODE)
5665 task_numa_fault(last_cpupid, nid, nr_pages, flags);
5666 return 0;
5667}
5668
5669static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
5670{
5671 struct vm_area_struct *vma = vmf->vma;
5672 if (vma_is_anonymous(vma))
5673 return do_huge_pmd_anonymous_page(vmf);
5674 if (vma->vm_ops->huge_fault)
5675 return vma->vm_ops->huge_fault(vmf, PMD_ORDER);
5676 return VM_FAULT_FALLBACK;
5677}
5678
5679/* `inline' is required to avoid gcc 4.1.2 build error */
5680static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
5681{
5682 struct vm_area_struct *vma = vmf->vma;
5683 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
5684 vm_fault_t ret;
5685
5686 if (vma_is_anonymous(vma)) {
5687 if (likely(!unshare) &&
5688 userfaultfd_huge_pmd_wp(vma, vmf->orig_pmd)) {
5689 if (userfaultfd_wp_async(vmf->vma))
5690 goto split;
5691 return handle_userfault(vmf, VM_UFFD_WP);
5692 }
5693 return do_huge_pmd_wp_page(vmf);
5694 }
5695
5696 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
5697 if (vma->vm_ops->huge_fault) {
5698 ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER);
5699 if (!(ret & VM_FAULT_FALLBACK))
5700 return ret;
5701 }
5702 }
5703
5704split:
5705 /* COW or write-notify handled on pte level: split pmd. */
5706 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
5707
5708 return VM_FAULT_FALLBACK;
5709}
5710
5711static vm_fault_t create_huge_pud(struct vm_fault *vmf)
5712{
5713#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
5714 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
5715 struct vm_area_struct *vma = vmf->vma;
5716 /* No support for anonymous transparent PUD pages yet */
5717 if (vma_is_anonymous(vma))
5718 return VM_FAULT_FALLBACK;
5719 if (vma->vm_ops->huge_fault)
5720 return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
5721#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
5722 return VM_FAULT_FALLBACK;
5723}
5724
5725static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
5726{
5727#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
5728 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
5729 struct vm_area_struct *vma = vmf->vma;
5730 vm_fault_t ret;
5731
5732 /* No support for anonymous transparent PUD pages yet */
5733 if (vma_is_anonymous(vma))
5734 goto split;
5735 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
5736 if (vma->vm_ops->huge_fault) {
5737 ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER);
5738 if (!(ret & VM_FAULT_FALLBACK))
5739 return ret;
5740 }
5741 }
5742split:
5743 /* COW or write-notify not handled on PUD level: split pud.*/
5744 __split_huge_pud(vma, vmf->pud, vmf->address);
5745#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
5746 return VM_FAULT_FALLBACK;
5747}
5748
5749/*
5750 * These routines also need to handle stuff like marking pages dirty
5751 * and/or accessed for architectures that don't do it in hardware (most
5752 * RISC architectures). The early dirtying is also good on the i386.
5753 *
5754 * There is also a hook called "update_mmu_cache()" that architectures
5755 * with external mmu caches can use to update those (ie the Sparc or
5756 * PowerPC hashed page tables that act as extended TLBs).
5757 *
5758 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
5759 * concurrent faults).
5760 *
5761 * The mmap_lock may have been released depending on flags and our return value.
5762 * See filemap_fault() and __folio_lock_or_retry().
5763 */
5764static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
5765{
5766 pte_t entry;
5767
5768 if (unlikely(pmd_none(*vmf->pmd))) {
5769 /*
5770 * Leave __pte_alloc() until later: because vm_ops->fault may
5771 * want to allocate huge page, and if we expose page table
5772 * for an instant, it will be difficult to retract from
5773 * concurrent faults and from rmap lookups.
5774 */
5775 vmf->pte = NULL;
5776 vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID;
5777 } else {
5778 pmd_t dummy_pmdval;
5779
5780 /*
5781 * A regular pmd is established and it can't morph into a huge
5782 * pmd by anon khugepaged, since that takes mmap_lock in write
5783 * mode; but shmem or file collapse to THP could still morph
5784 * it into a huge pmd: just retry later if so.
5785 *
5786 * Use the maywrite version to indicate that vmf->pte may be
5787 * modified, but since we will use pte_same() to detect the
5788 * change of the !pte_none() entry, there is no need to recheck
5789 * the pmdval. Here we chooes to pass a dummy variable instead
5790 * of NULL, which helps new user think about why this place is
5791 * special.
5792 */
5793 vmf->pte = pte_offset_map_rw_nolock(vmf->vma->vm_mm, vmf->pmd,
5794 vmf->address, &dummy_pmdval,
5795 &vmf->ptl);
5796 if (unlikely(!vmf->pte))
5797 return 0;
5798 vmf->orig_pte = ptep_get_lockless(vmf->pte);
5799 vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID;
5800
5801 if (pte_none(vmf->orig_pte)) {
5802 pte_unmap(vmf->pte);
5803 vmf->pte = NULL;
5804 }
5805 }
5806
5807 if (!vmf->pte)
5808 return do_pte_missing(vmf);
5809
5810 if (!pte_present(vmf->orig_pte))
5811 return do_swap_page(vmf);
5812
5813 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
5814 return do_numa_page(vmf);
5815
5816 spin_lock(vmf->ptl);
5817 entry = vmf->orig_pte;
5818 if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) {
5819 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
5820 goto unlock;
5821 }
5822 if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
5823 if (!pte_write(entry))
5824 return do_wp_page(vmf);
5825 else if (likely(vmf->flags & FAULT_FLAG_WRITE))
5826 entry = pte_mkdirty(entry);
5827 }
5828 entry = pte_mkyoung(entry);
5829 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
5830 vmf->flags & FAULT_FLAG_WRITE)) {
5831 update_mmu_cache_range(vmf, vmf->vma, vmf->address,
5832 vmf->pte, 1);
5833 } else {
5834 /* Skip spurious TLB flush for retried page fault */
5835 if (vmf->flags & FAULT_FLAG_TRIED)
5836 goto unlock;
5837 /*
5838 * This is needed only for protection faults but the arch code
5839 * is not yet telling us if this is a protection fault or not.
5840 * This still avoids useless tlb flushes for .text page faults
5841 * with threads.
5842 */
5843 if (vmf->flags & FAULT_FLAG_WRITE)
5844 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address,
5845 vmf->pte);
5846 }
5847unlock:
5848 pte_unmap_unlock(vmf->pte, vmf->ptl);
5849 return 0;
5850}
5851
5852/*
5853 * On entry, we hold either the VMA lock or the mmap_lock
5854 * (FAULT_FLAG_VMA_LOCK tells you which). If VM_FAULT_RETRY is set in
5855 * the result, the mmap_lock is not held on exit. See filemap_fault()
5856 * and __folio_lock_or_retry().
5857 */
5858static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
5859 unsigned long address, unsigned int flags)
5860{
5861 struct vm_fault vmf = {
5862 .vma = vma,
5863 .address = address & PAGE_MASK,
5864 .real_address = address,
5865 .flags = flags,
5866 .pgoff = linear_page_index(vma, address),
5867 .gfp_mask = __get_fault_gfp_mask(vma),
5868 };
5869 struct mm_struct *mm = vma->vm_mm;
5870 unsigned long vm_flags = vma->vm_flags;
5871 pgd_t *pgd;
5872 p4d_t *p4d;
5873 vm_fault_t ret;
5874
5875 pgd = pgd_offset(mm, address);
5876 p4d = p4d_alloc(mm, pgd, address);
5877 if (!p4d)
5878 return VM_FAULT_OOM;
5879
5880 vmf.pud = pud_alloc(mm, p4d, address);
5881 if (!vmf.pud)
5882 return VM_FAULT_OOM;
5883retry_pud:
5884 if (pud_none(*vmf.pud) &&
5885 thp_vma_allowable_order(vma, vm_flags,
5886 TVA_IN_PF | TVA_ENFORCE_SYSFS, PUD_ORDER)) {
5887 ret = create_huge_pud(&vmf);
5888 if (!(ret & VM_FAULT_FALLBACK))
5889 return ret;
5890 } else {
5891 pud_t orig_pud = *vmf.pud;
5892
5893 barrier();
5894 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
5895
5896 /*
5897 * TODO once we support anonymous PUDs: NUMA case and
5898 * FAULT_FLAG_UNSHARE handling.
5899 */
5900 if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) {
5901 ret = wp_huge_pud(&vmf, orig_pud);
5902 if (!(ret & VM_FAULT_FALLBACK))
5903 return ret;
5904 } else {
5905 huge_pud_set_accessed(&vmf, orig_pud);
5906 return 0;
5907 }
5908 }
5909 }
5910
5911 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
5912 if (!vmf.pmd)
5913 return VM_FAULT_OOM;
5914
5915 /* Huge pud page fault raced with pmd_alloc? */
5916 if (pud_trans_unstable(vmf.pud))
5917 goto retry_pud;
5918
5919 if (pmd_none(*vmf.pmd) &&
5920 thp_vma_allowable_order(vma, vm_flags,
5921 TVA_IN_PF | TVA_ENFORCE_SYSFS, PMD_ORDER)) {
5922 ret = create_huge_pmd(&vmf);
5923 if (!(ret & VM_FAULT_FALLBACK))
5924 return ret;
5925 } else {
5926 vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
5927
5928 if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
5929 VM_BUG_ON(thp_migration_supported() &&
5930 !is_pmd_migration_entry(vmf.orig_pmd));
5931 if (is_pmd_migration_entry(vmf.orig_pmd))
5932 pmd_migration_entry_wait(mm, vmf.pmd);
5933 return 0;
5934 }
5935 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
5936 if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
5937 return do_huge_pmd_numa_page(&vmf);
5938
5939 if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
5940 !pmd_write(vmf.orig_pmd)) {
5941 ret = wp_huge_pmd(&vmf);
5942 if (!(ret & VM_FAULT_FALLBACK))
5943 return ret;
5944 } else {
5945 huge_pmd_set_accessed(&vmf);
5946 return 0;
5947 }
5948 }
5949 }
5950
5951 return handle_pte_fault(&vmf);
5952}
5953
5954/**
5955 * mm_account_fault - Do page fault accounting
5956 * @mm: mm from which memcg should be extracted. It can be NULL.
5957 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
5958 * of perf event counters, but we'll still do the per-task accounting to
5959 * the task who triggered this page fault.
5960 * @address: the faulted address.
5961 * @flags: the fault flags.
5962 * @ret: the fault retcode.
5963 *
5964 * This will take care of most of the page fault accounting. Meanwhile, it
5965 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
5966 * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
5967 * still be in per-arch page fault handlers at the entry of page fault.
5968 */
5969static inline void mm_account_fault(struct mm_struct *mm, struct pt_regs *regs,
5970 unsigned long address, unsigned int flags,
5971 vm_fault_t ret)
5972{
5973 bool major;
5974
5975 /* Incomplete faults will be accounted upon completion. */
5976 if (ret & VM_FAULT_RETRY)
5977 return;
5978
5979 /*
5980 * To preserve the behavior of older kernels, PGFAULT counters record
5981 * both successful and failed faults, as opposed to perf counters,
5982 * which ignore failed cases.
5983 */
5984 count_vm_event(PGFAULT);
5985 count_memcg_event_mm(mm, PGFAULT);
5986
5987 /*
5988 * Do not account for unsuccessful faults (e.g. when the address wasn't
5989 * valid). That includes arch_vma_access_permitted() failing before
5990 * reaching here. So this is not a "this many hardware page faults"
5991 * counter. We should use the hw profiling for that.
5992 */
5993 if (ret & VM_FAULT_ERROR)
5994 return;
5995
5996 /*
5997 * We define the fault as a major fault when the final successful fault
5998 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
5999 * handle it immediately previously).
6000 */
6001 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
6002
6003 if (major)
6004 current->maj_flt++;
6005 else
6006 current->min_flt++;
6007
6008 /*
6009 * If the fault is done for GUP, regs will be NULL. We only do the
6010 * accounting for the per thread fault counters who triggered the
6011 * fault, and we skip the perf event updates.
6012 */
6013 if (!regs)
6014 return;
6015
6016 if (major)
6017 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
6018 else
6019 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
6020}
6021
6022#ifdef CONFIG_LRU_GEN
6023static void lru_gen_enter_fault(struct vm_area_struct *vma)
6024{
6025 /* the LRU algorithm only applies to accesses with recency */
6026 current->in_lru_fault = vma_has_recency(vma);
6027}
6028
6029static void lru_gen_exit_fault(void)
6030{
6031 current->in_lru_fault = false;
6032}
6033#else
6034static void lru_gen_enter_fault(struct vm_area_struct *vma)
6035{
6036}
6037
6038static void lru_gen_exit_fault(void)
6039{
6040}
6041#endif /* CONFIG_LRU_GEN */
6042
6043static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma,
6044 unsigned int *flags)
6045{
6046 if (unlikely(*flags & FAULT_FLAG_UNSHARE)) {
6047 if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE))
6048 return VM_FAULT_SIGSEGV;
6049 /*
6050 * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's
6051 * just treat it like an ordinary read-fault otherwise.
6052 */
6053 if (!is_cow_mapping(vma->vm_flags))
6054 *flags &= ~FAULT_FLAG_UNSHARE;
6055 } else if (*flags & FAULT_FLAG_WRITE) {
6056 /* Write faults on read-only mappings are impossible ... */
6057 if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE)))
6058 return VM_FAULT_SIGSEGV;
6059 /* ... and FOLL_FORCE only applies to COW mappings. */
6060 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) &&
6061 !is_cow_mapping(vma->vm_flags)))
6062 return VM_FAULT_SIGSEGV;
6063 }
6064#ifdef CONFIG_PER_VMA_LOCK
6065 /*
6066 * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of
6067 * the assumption that lock is dropped on VM_FAULT_RETRY.
6068 */
6069 if (WARN_ON_ONCE((*flags &
6070 (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) ==
6071 (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)))
6072 return VM_FAULT_SIGSEGV;
6073#endif
6074
6075 return 0;
6076}
6077
6078/*
6079 * By the time we get here, we already hold the mm semaphore
6080 *
6081 * The mmap_lock may have been released depending on flags and our
6082 * return value. See filemap_fault() and __folio_lock_or_retry().
6083 */
6084vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
6085 unsigned int flags, struct pt_regs *regs)
6086{
6087 /* If the fault handler drops the mmap_lock, vma may be freed */
6088 struct mm_struct *mm = vma->vm_mm;
6089 vm_fault_t ret;
6090 bool is_droppable;
6091
6092 __set_current_state(TASK_RUNNING);
6093
6094 ret = sanitize_fault_flags(vma, &flags);
6095 if (ret)
6096 goto out;
6097
6098 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
6099 flags & FAULT_FLAG_INSTRUCTION,
6100 flags & FAULT_FLAG_REMOTE)) {
6101 ret = VM_FAULT_SIGSEGV;
6102 goto out;
6103 }
6104
6105 is_droppable = !!(vma->vm_flags & VM_DROPPABLE);
6106
6107 /*
6108 * Enable the memcg OOM handling for faults triggered in user
6109 * space. Kernel faults are handled more gracefully.
6110 */
6111 if (flags & FAULT_FLAG_USER)
6112 mem_cgroup_enter_user_fault();
6113
6114 lru_gen_enter_fault(vma);
6115
6116 if (unlikely(is_vm_hugetlb_page(vma)))
6117 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
6118 else
6119 ret = __handle_mm_fault(vma, address, flags);
6120
6121 /*
6122 * Warning: It is no longer safe to dereference vma-> after this point,
6123 * because mmap_lock might have been dropped by __handle_mm_fault(), so
6124 * vma might be destroyed from underneath us.
6125 */
6126
6127 lru_gen_exit_fault();
6128
6129 /* If the mapping is droppable, then errors due to OOM aren't fatal. */
6130 if (is_droppable)
6131 ret &= ~VM_FAULT_OOM;
6132
6133 if (flags & FAULT_FLAG_USER) {
6134 mem_cgroup_exit_user_fault();
6135 /*
6136 * The task may have entered a memcg OOM situation but
6137 * if the allocation error was handled gracefully (no
6138 * VM_FAULT_OOM), there is no need to kill anything.
6139 * Just clean up the OOM state peacefully.
6140 */
6141 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
6142 mem_cgroup_oom_synchronize(false);
6143 }
6144out:
6145 mm_account_fault(mm, regs, address, flags, ret);
6146
6147 return ret;
6148}
6149EXPORT_SYMBOL_GPL(handle_mm_fault);
6150
6151#ifdef CONFIG_LOCK_MM_AND_FIND_VMA
6152#include <linux/extable.h>
6153
6154static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
6155{
6156 if (likely(mmap_read_trylock(mm)))
6157 return true;
6158
6159 if (regs && !user_mode(regs)) {
6160 unsigned long ip = exception_ip(regs);
6161 if (!search_exception_tables(ip))
6162 return false;
6163 }
6164
6165 return !mmap_read_lock_killable(mm);
6166}
6167
6168static inline bool mmap_upgrade_trylock(struct mm_struct *mm)
6169{
6170 /*
6171 * We don't have this operation yet.
6172 *
6173 * It should be easy enough to do: it's basically a
6174 * atomic_long_try_cmpxchg_acquire()
6175 * from RWSEM_READER_BIAS -> RWSEM_WRITER_LOCKED, but
6176 * it also needs the proper lockdep magic etc.
6177 */
6178 return false;
6179}
6180
6181static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
6182{
6183 mmap_read_unlock(mm);
6184 if (regs && !user_mode(regs)) {
6185 unsigned long ip = exception_ip(regs);
6186 if (!search_exception_tables(ip))
6187 return false;
6188 }
6189 return !mmap_write_lock_killable(mm);
6190}
6191
6192/*
6193 * Helper for page fault handling.
6194 *
6195 * This is kind of equivalend to "mmap_read_lock()" followed
6196 * by "find_extend_vma()", except it's a lot more careful about
6197 * the locking (and will drop the lock on failure).
6198 *
6199 * For example, if we have a kernel bug that causes a page
6200 * fault, we don't want to just use mmap_read_lock() to get
6201 * the mm lock, because that would deadlock if the bug were
6202 * to happen while we're holding the mm lock for writing.
6203 *
6204 * So this checks the exception tables on kernel faults in
6205 * order to only do this all for instructions that are actually
6206 * expected to fault.
6207 *
6208 * We can also actually take the mm lock for writing if we
6209 * need to extend the vma, which helps the VM layer a lot.
6210 */
6211struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
6212 unsigned long addr, struct pt_regs *regs)
6213{
6214 struct vm_area_struct *vma;
6215
6216 if (!get_mmap_lock_carefully(mm, regs))
6217 return NULL;
6218
6219 vma = find_vma(mm, addr);
6220 if (likely(vma && (vma->vm_start <= addr)))
6221 return vma;
6222
6223 /*
6224 * Well, dang. We might still be successful, but only
6225 * if we can extend a vma to do so.
6226 */
6227 if (!vma || !(vma->vm_flags & VM_GROWSDOWN)) {
6228 mmap_read_unlock(mm);
6229 return NULL;
6230 }
6231
6232 /*
6233 * We can try to upgrade the mmap lock atomically,
6234 * in which case we can continue to use the vma
6235 * we already looked up.
6236 *
6237 * Otherwise we'll have to drop the mmap lock and
6238 * re-take it, and also look up the vma again,
6239 * re-checking it.
6240 */
6241 if (!mmap_upgrade_trylock(mm)) {
6242 if (!upgrade_mmap_lock_carefully(mm, regs))
6243 return NULL;
6244
6245 vma = find_vma(mm, addr);
6246 if (!vma)
6247 goto fail;
6248 if (vma->vm_start <= addr)
6249 goto success;
6250 if (!(vma->vm_flags & VM_GROWSDOWN))
6251 goto fail;
6252 }
6253
6254 if (expand_stack_locked(vma, addr))
6255 goto fail;
6256
6257success:
6258 mmap_write_downgrade(mm);
6259 return vma;
6260
6261fail:
6262 mmap_write_unlock(mm);
6263 return NULL;
6264}
6265#endif
6266
6267#ifdef CONFIG_PER_VMA_LOCK
6268/*
6269 * Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be
6270 * stable and not isolated. If the VMA is not found or is being modified the
6271 * function returns NULL.
6272 */
6273struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
6274 unsigned long address)
6275{
6276 MA_STATE(mas, &mm->mm_mt, address, address);
6277 struct vm_area_struct *vma;
6278
6279 rcu_read_lock();
6280retry:
6281 vma = mas_walk(&mas);
6282 if (!vma)
6283 goto inval;
6284
6285 if (!vma_start_read(vma))
6286 goto inval;
6287
6288 /* Check if the VMA got isolated after we found it */
6289 if (vma->detached) {
6290 vma_end_read(vma);
6291 count_vm_vma_lock_event(VMA_LOCK_MISS);
6292 /* The area was replaced with another one */
6293 goto retry;
6294 }
6295 /*
6296 * At this point, we have a stable reference to a VMA: The VMA is
6297 * locked and we know it hasn't already been isolated.
6298 * From here on, we can access the VMA without worrying about which
6299 * fields are accessible for RCU readers.
6300 */
6301
6302 /* Check since vm_start/vm_end might change before we lock the VMA */
6303 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
6304 goto inval_end_read;
6305
6306 rcu_read_unlock();
6307 return vma;
6308
6309inval_end_read:
6310 vma_end_read(vma);
6311inval:
6312 rcu_read_unlock();
6313 count_vm_vma_lock_event(VMA_LOCK_ABORT);
6314 return NULL;
6315}
6316#endif /* CONFIG_PER_VMA_LOCK */
6317
6318#ifndef __PAGETABLE_P4D_FOLDED
6319/*
6320 * Allocate p4d page table.
6321 * We've already handled the fast-path in-line.
6322 */
6323int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
6324{
6325 p4d_t *new = p4d_alloc_one(mm, address);
6326 if (!new)
6327 return -ENOMEM;
6328
6329 spin_lock(&mm->page_table_lock);
6330 if (pgd_present(*pgd)) { /* Another has populated it */
6331 p4d_free(mm, new);
6332 } else {
6333 smp_wmb(); /* See comment in pmd_install() */
6334 pgd_populate(mm, pgd, new);
6335 }
6336 spin_unlock(&mm->page_table_lock);
6337 return 0;
6338}
6339#endif /* __PAGETABLE_P4D_FOLDED */
6340
6341#ifndef __PAGETABLE_PUD_FOLDED
6342/*
6343 * Allocate page upper directory.
6344 * We've already handled the fast-path in-line.
6345 */
6346int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
6347{
6348 pud_t *new = pud_alloc_one(mm, address);
6349 if (!new)
6350 return -ENOMEM;
6351
6352 spin_lock(&mm->page_table_lock);
6353 if (!p4d_present(*p4d)) {
6354 mm_inc_nr_puds(mm);
6355 smp_wmb(); /* See comment in pmd_install() */
6356 p4d_populate(mm, p4d, new);
6357 } else /* Another has populated it */
6358 pud_free(mm, new);
6359 spin_unlock(&mm->page_table_lock);
6360 return 0;
6361}
6362#endif /* __PAGETABLE_PUD_FOLDED */
6363
6364#ifndef __PAGETABLE_PMD_FOLDED
6365/*
6366 * Allocate page middle directory.
6367 * We've already handled the fast-path in-line.
6368 */
6369int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
6370{
6371 spinlock_t *ptl;
6372 pmd_t *new = pmd_alloc_one(mm, address);
6373 if (!new)
6374 return -ENOMEM;
6375
6376 ptl = pud_lock(mm, pud);
6377 if (!pud_present(*pud)) {
6378 mm_inc_nr_pmds(mm);
6379 smp_wmb(); /* See comment in pmd_install() */
6380 pud_populate(mm, pud, new);
6381 } else { /* Another has populated it */
6382 pmd_free(mm, new);
6383 }
6384 spin_unlock(ptl);
6385 return 0;
6386}
6387#endif /* __PAGETABLE_PMD_FOLDED */
6388
6389static inline void pfnmap_args_setup(struct follow_pfnmap_args *args,
6390 spinlock_t *lock, pte_t *ptep,
6391 pgprot_t pgprot, unsigned long pfn_base,
6392 unsigned long addr_mask, bool writable,
6393 bool special)
6394{
6395 args->lock = lock;
6396 args->ptep = ptep;
6397 args->pfn = pfn_base + ((args->address & ~addr_mask) >> PAGE_SHIFT);
6398 args->pgprot = pgprot;
6399 args->writable = writable;
6400 args->special = special;
6401}
6402
6403static inline void pfnmap_lockdep_assert(struct vm_area_struct *vma)
6404{
6405#ifdef CONFIG_LOCKDEP
6406 struct file *file = vma->vm_file;
6407 struct address_space *mapping = file ? file->f_mapping : NULL;
6408
6409 if (mapping)
6410 lockdep_assert(lockdep_is_held(&mapping->i_mmap_rwsem) ||
6411 lockdep_is_held(&vma->vm_mm->mmap_lock));
6412 else
6413 lockdep_assert(lockdep_is_held(&vma->vm_mm->mmap_lock));
6414#endif
6415}
6416
6417/**
6418 * follow_pfnmap_start() - Look up a pfn mapping at a user virtual address
6419 * @args: Pointer to struct @follow_pfnmap_args
6420 *
6421 * The caller needs to setup args->vma and args->address to point to the
6422 * virtual address as the target of such lookup. On a successful return,
6423 * the results will be put into other output fields.
6424 *
6425 * After the caller finished using the fields, the caller must invoke
6426 * another follow_pfnmap_end() to proper releases the locks and resources
6427 * of such look up request.
6428 *
6429 * During the start() and end() calls, the results in @args will be valid
6430 * as proper locks will be held. After the end() is called, all the fields
6431 * in @follow_pfnmap_args will be invalid to be further accessed. Further
6432 * use of such information after end() may require proper synchronizations
6433 * by the caller with page table updates, otherwise it can create a
6434 * security bug.
6435 *
6436 * If the PTE maps a refcounted page, callers are responsible to protect
6437 * against invalidation with MMU notifiers; otherwise access to the PFN at
6438 * a later point in time can trigger use-after-free.
6439 *
6440 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
6441 * should be taken for read, and the mmap semaphore cannot be released
6442 * before the end() is invoked.
6443 *
6444 * This function must not be used to modify PTE content.
6445 *
6446 * Return: zero on success, negative otherwise.
6447 */
6448int follow_pfnmap_start(struct follow_pfnmap_args *args)
6449{
6450 struct vm_area_struct *vma = args->vma;
6451 unsigned long address = args->address;
6452 struct mm_struct *mm = vma->vm_mm;
6453 spinlock_t *lock;
6454 pgd_t *pgdp;
6455 p4d_t *p4dp, p4d;
6456 pud_t *pudp, pud;
6457 pmd_t *pmdp, pmd;
6458 pte_t *ptep, pte;
6459
6460 pfnmap_lockdep_assert(vma);
6461
6462 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
6463 goto out;
6464
6465 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
6466 goto out;
6467retry:
6468 pgdp = pgd_offset(mm, address);
6469 if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp)))
6470 goto out;
6471
6472 p4dp = p4d_offset(pgdp, address);
6473 p4d = READ_ONCE(*p4dp);
6474 if (p4d_none(p4d) || unlikely(p4d_bad(p4d)))
6475 goto out;
6476
6477 pudp = pud_offset(p4dp, address);
6478 pud = READ_ONCE(*pudp);
6479 if (pud_none(pud))
6480 goto out;
6481 if (pud_leaf(pud)) {
6482 lock = pud_lock(mm, pudp);
6483 if (!unlikely(pud_leaf(pud))) {
6484 spin_unlock(lock);
6485 goto retry;
6486 }
6487 pfnmap_args_setup(args, lock, NULL, pud_pgprot(pud),
6488 pud_pfn(pud), PUD_MASK, pud_write(pud),
6489 pud_special(pud));
6490 return 0;
6491 }
6492
6493 pmdp = pmd_offset(pudp, address);
6494 pmd = pmdp_get_lockless(pmdp);
6495 if (pmd_leaf(pmd)) {
6496 lock = pmd_lock(mm, pmdp);
6497 if (!unlikely(pmd_leaf(pmd))) {
6498 spin_unlock(lock);
6499 goto retry;
6500 }
6501 pfnmap_args_setup(args, lock, NULL, pmd_pgprot(pmd),
6502 pmd_pfn(pmd), PMD_MASK, pmd_write(pmd),
6503 pmd_special(pmd));
6504 return 0;
6505 }
6506
6507 ptep = pte_offset_map_lock(mm, pmdp, address, &lock);
6508 if (!ptep)
6509 goto out;
6510 pte = ptep_get(ptep);
6511 if (!pte_present(pte))
6512 goto unlock;
6513 pfnmap_args_setup(args, lock, ptep, pte_pgprot(pte),
6514 pte_pfn(pte), PAGE_MASK, pte_write(pte),
6515 pte_special(pte));
6516 return 0;
6517unlock:
6518 pte_unmap_unlock(ptep, lock);
6519out:
6520 return -EINVAL;
6521}
6522EXPORT_SYMBOL_GPL(follow_pfnmap_start);
6523
6524/**
6525 * follow_pfnmap_end(): End a follow_pfnmap_start() process
6526 * @args: Pointer to struct @follow_pfnmap_args
6527 *
6528 * Must be used in pair of follow_pfnmap_start(). See the start() function
6529 * above for more information.
6530 */
6531void follow_pfnmap_end(struct follow_pfnmap_args *args)
6532{
6533 if (args->lock)
6534 spin_unlock(args->lock);
6535 if (args->ptep)
6536 pte_unmap(args->ptep);
6537}
6538EXPORT_SYMBOL_GPL(follow_pfnmap_end);
6539
6540#ifdef CONFIG_HAVE_IOREMAP_PROT
6541/**
6542 * generic_access_phys - generic implementation for iomem mmap access
6543 * @vma: the vma to access
6544 * @addr: userspace address, not relative offset within @vma
6545 * @buf: buffer to read/write
6546 * @len: length of transfer
6547 * @write: set to FOLL_WRITE when writing, otherwise reading
6548 *
6549 * This is a generic implementation for &vm_operations_struct.access for an
6550 * iomem mapping. This callback is used by access_process_vm() when the @vma is
6551 * not page based.
6552 */
6553int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
6554 void *buf, int len, int write)
6555{
6556 resource_size_t phys_addr;
6557 unsigned long prot = 0;
6558 void __iomem *maddr;
6559 int offset = offset_in_page(addr);
6560 int ret = -EINVAL;
6561 bool writable;
6562 struct follow_pfnmap_args args = { .vma = vma, .address = addr };
6563
6564retry:
6565 if (follow_pfnmap_start(&args))
6566 return -EINVAL;
6567 prot = pgprot_val(args.pgprot);
6568 phys_addr = (resource_size_t)args.pfn << PAGE_SHIFT;
6569 writable = args.writable;
6570 follow_pfnmap_end(&args);
6571
6572 if ((write & FOLL_WRITE) && !writable)
6573 return -EINVAL;
6574
6575 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
6576 if (!maddr)
6577 return -ENOMEM;
6578
6579 if (follow_pfnmap_start(&args))
6580 goto out_unmap;
6581
6582 if ((prot != pgprot_val(args.pgprot)) ||
6583 (phys_addr != (args.pfn << PAGE_SHIFT)) ||
6584 (writable != args.writable)) {
6585 follow_pfnmap_end(&args);
6586 iounmap(maddr);
6587 goto retry;
6588 }
6589
6590 if (write)
6591 memcpy_toio(maddr + offset, buf, len);
6592 else
6593 memcpy_fromio(buf, maddr + offset, len);
6594 ret = len;
6595 follow_pfnmap_end(&args);
6596out_unmap:
6597 iounmap(maddr);
6598
6599 return ret;
6600}
6601EXPORT_SYMBOL_GPL(generic_access_phys);
6602#endif
6603
6604/*
6605 * Access another process' address space as given in mm.
6606 */
6607static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
6608 void *buf, int len, unsigned int gup_flags)
6609{
6610 void *old_buf = buf;
6611 int write = gup_flags & FOLL_WRITE;
6612
6613 if (mmap_read_lock_killable(mm))
6614 return 0;
6615
6616 /* Untag the address before looking up the VMA */
6617 addr = untagged_addr_remote(mm, addr);
6618
6619 /* Avoid triggering the temporary warning in __get_user_pages */
6620 if (!vma_lookup(mm, addr) && !expand_stack(mm, addr))
6621 return 0;
6622
6623 /* ignore errors, just check how much was successfully transferred */
6624 while (len) {
6625 int bytes, offset;
6626 void *maddr;
6627 struct vm_area_struct *vma = NULL;
6628 struct page *page = get_user_page_vma_remote(mm, addr,
6629 gup_flags, &vma);
6630
6631 if (IS_ERR(page)) {
6632 /* We might need to expand the stack to access it */
6633 vma = vma_lookup(mm, addr);
6634 if (!vma) {
6635 vma = expand_stack(mm, addr);
6636
6637 /* mmap_lock was dropped on failure */
6638 if (!vma)
6639 return buf - old_buf;
6640
6641 /* Try again if stack expansion worked */
6642 continue;
6643 }
6644
6645 /*
6646 * Check if this is a VM_IO | VM_PFNMAP VMA, which
6647 * we can access using slightly different code.
6648 */
6649 bytes = 0;
6650#ifdef CONFIG_HAVE_IOREMAP_PROT
6651 if (vma->vm_ops && vma->vm_ops->access)
6652 bytes = vma->vm_ops->access(vma, addr, buf,
6653 len, write);
6654#endif
6655 if (bytes <= 0)
6656 break;
6657 } else {
6658 bytes = len;
6659 offset = addr & (PAGE_SIZE-1);
6660 if (bytes > PAGE_SIZE-offset)
6661 bytes = PAGE_SIZE-offset;
6662
6663 maddr = kmap_local_page(page);
6664 if (write) {
6665 copy_to_user_page(vma, page, addr,
6666 maddr + offset, buf, bytes);
6667 set_page_dirty_lock(page);
6668 } else {
6669 copy_from_user_page(vma, page, addr,
6670 buf, maddr + offset, bytes);
6671 }
6672 unmap_and_put_page(page, maddr);
6673 }
6674 len -= bytes;
6675 buf += bytes;
6676 addr += bytes;
6677 }
6678 mmap_read_unlock(mm);
6679
6680 return buf - old_buf;
6681}
6682
6683/**
6684 * access_remote_vm - access another process' address space
6685 * @mm: the mm_struct of the target address space
6686 * @addr: start address to access
6687 * @buf: source or destination buffer
6688 * @len: number of bytes to transfer
6689 * @gup_flags: flags modifying lookup behaviour
6690 *
6691 * The caller must hold a reference on @mm.
6692 *
6693 * Return: number of bytes copied from source to destination.
6694 */
6695int access_remote_vm(struct mm_struct *mm, unsigned long addr,
6696 void *buf, int len, unsigned int gup_flags)
6697{
6698 return __access_remote_vm(mm, addr, buf, len, gup_flags);
6699}
6700
6701/*
6702 * Access another process' address space.
6703 * Source/target buffer must be kernel space,
6704 * Do not walk the page table directly, use get_user_pages
6705 */
6706int access_process_vm(struct task_struct *tsk, unsigned long addr,
6707 void *buf, int len, unsigned int gup_flags)
6708{
6709 struct mm_struct *mm;
6710 int ret;
6711
6712 mm = get_task_mm(tsk);
6713 if (!mm)
6714 return 0;
6715
6716 ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
6717
6718 mmput(mm);
6719
6720 return ret;
6721}
6722EXPORT_SYMBOL_GPL(access_process_vm);
6723
6724/*
6725 * Print the name of a VMA.
6726 */
6727void print_vma_addr(char *prefix, unsigned long ip)
6728{
6729 struct mm_struct *mm = current->mm;
6730 struct vm_area_struct *vma;
6731
6732 /*
6733 * we might be running from an atomic context so we cannot sleep
6734 */
6735 if (!mmap_read_trylock(mm))
6736 return;
6737
6738 vma = vma_lookup(mm, ip);
6739 if (vma && vma->vm_file) {
6740 struct file *f = vma->vm_file;
6741 ip -= vma->vm_start;
6742 ip += vma->vm_pgoff << PAGE_SHIFT;
6743 printk("%s%pD[%lx,%lx+%lx]", prefix, f, ip,
6744 vma->vm_start,
6745 vma->vm_end - vma->vm_start);
6746 }
6747 mmap_read_unlock(mm);
6748}
6749
6750#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
6751void __might_fault(const char *file, int line)
6752{
6753 if (pagefault_disabled())
6754 return;
6755 __might_sleep(file, line);
6756#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
6757 if (current->mm)
6758 might_lock_read(¤t->mm->mmap_lock);
6759#endif
6760}
6761EXPORT_SYMBOL(__might_fault);
6762#endif
6763
6764#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
6765/*
6766 * Process all subpages of the specified huge page with the specified
6767 * operation. The target subpage will be processed last to keep its
6768 * cache lines hot.
6769 */
6770static inline int process_huge_page(
6771 unsigned long addr_hint, unsigned int nr_pages,
6772 int (*process_subpage)(unsigned long addr, int idx, void *arg),
6773 void *arg)
6774{
6775 int i, n, base, l, ret;
6776 unsigned long addr = addr_hint &
6777 ~(((unsigned long)nr_pages << PAGE_SHIFT) - 1);
6778
6779 /* Process target subpage last to keep its cache lines hot */
6780 might_sleep();
6781 n = (addr_hint - addr) / PAGE_SIZE;
6782 if (2 * n <= nr_pages) {
6783 /* If target subpage in first half of huge page */
6784 base = 0;
6785 l = n;
6786 /* Process subpages at the end of huge page */
6787 for (i = nr_pages - 1; i >= 2 * n; i--) {
6788 cond_resched();
6789 ret = process_subpage(addr + i * PAGE_SIZE, i, arg);
6790 if (ret)
6791 return ret;
6792 }
6793 } else {
6794 /* If target subpage in second half of huge page */
6795 base = nr_pages - 2 * (nr_pages - n);
6796 l = nr_pages - n;
6797 /* Process subpages at the begin of huge page */
6798 for (i = 0; i < base; i++) {
6799 cond_resched();
6800 ret = process_subpage(addr + i * PAGE_SIZE, i, arg);
6801 if (ret)
6802 return ret;
6803 }
6804 }
6805 /*
6806 * Process remaining subpages in left-right-left-right pattern
6807 * towards the target subpage
6808 */
6809 for (i = 0; i < l; i++) {
6810 int left_idx = base + i;
6811 int right_idx = base + 2 * l - 1 - i;
6812
6813 cond_resched();
6814 ret = process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
6815 if (ret)
6816 return ret;
6817 cond_resched();
6818 ret = process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
6819 if (ret)
6820 return ret;
6821 }
6822 return 0;
6823}
6824
6825static void clear_gigantic_page(struct folio *folio, unsigned long addr_hint,
6826 unsigned int nr_pages)
6827{
6828 unsigned long addr = ALIGN_DOWN(addr_hint, folio_size(folio));
6829 int i;
6830
6831 might_sleep();
6832 for (i = 0; i < nr_pages; i++) {
6833 cond_resched();
6834 clear_user_highpage(folio_page(folio, i), addr + i * PAGE_SIZE);
6835 }
6836}
6837
6838static int clear_subpage(unsigned long addr, int idx, void *arg)
6839{
6840 struct folio *folio = arg;
6841
6842 clear_user_highpage(folio_page(folio, idx), addr);
6843 return 0;
6844}
6845
6846/**
6847 * folio_zero_user - Zero a folio which will be mapped to userspace.
6848 * @folio: The folio to zero.
6849 * @addr_hint: The address will be accessed or the base address if uncelar.
6850 */
6851void folio_zero_user(struct folio *folio, unsigned long addr_hint)
6852{
6853 unsigned int nr_pages = folio_nr_pages(folio);
6854
6855 if (unlikely(nr_pages > MAX_ORDER_NR_PAGES))
6856 clear_gigantic_page(folio, addr_hint, nr_pages);
6857 else
6858 process_huge_page(addr_hint, nr_pages, clear_subpage, folio);
6859}
6860
6861static int copy_user_gigantic_page(struct folio *dst, struct folio *src,
6862 unsigned long addr_hint,
6863 struct vm_area_struct *vma,
6864 unsigned int nr_pages)
6865{
6866 unsigned long addr = ALIGN_DOWN(addr_hint, folio_size(dst));
6867 struct page *dst_page;
6868 struct page *src_page;
6869 int i;
6870
6871 for (i = 0; i < nr_pages; i++) {
6872 dst_page = folio_page(dst, i);
6873 src_page = folio_page(src, i);
6874
6875 cond_resched();
6876 if (copy_mc_user_highpage(dst_page, src_page,
6877 addr + i*PAGE_SIZE, vma))
6878 return -EHWPOISON;
6879 }
6880 return 0;
6881}
6882
6883struct copy_subpage_arg {
6884 struct folio *dst;
6885 struct folio *src;
6886 struct vm_area_struct *vma;
6887};
6888
6889static int copy_subpage(unsigned long addr, int idx, void *arg)
6890{
6891 struct copy_subpage_arg *copy_arg = arg;
6892 struct page *dst = folio_page(copy_arg->dst, idx);
6893 struct page *src = folio_page(copy_arg->src, idx);
6894
6895 if (copy_mc_user_highpage(dst, src, addr, copy_arg->vma))
6896 return -EHWPOISON;
6897 return 0;
6898}
6899
6900int copy_user_large_folio(struct folio *dst, struct folio *src,
6901 unsigned long addr_hint, struct vm_area_struct *vma)
6902{
6903 unsigned int nr_pages = folio_nr_pages(dst);
6904 struct copy_subpage_arg arg = {
6905 .dst = dst,
6906 .src = src,
6907 .vma = vma,
6908 };
6909
6910 if (unlikely(nr_pages > MAX_ORDER_NR_PAGES))
6911 return copy_user_gigantic_page(dst, src, addr_hint, vma, nr_pages);
6912
6913 return process_huge_page(addr_hint, nr_pages, copy_subpage, &arg);
6914}
6915
6916long copy_folio_from_user(struct folio *dst_folio,
6917 const void __user *usr_src,
6918 bool allow_pagefault)
6919{
6920 void *kaddr;
6921 unsigned long i, rc = 0;
6922 unsigned int nr_pages = folio_nr_pages(dst_folio);
6923 unsigned long ret_val = nr_pages * PAGE_SIZE;
6924 struct page *subpage;
6925
6926 for (i = 0; i < nr_pages; i++) {
6927 subpage = folio_page(dst_folio, i);
6928 kaddr = kmap_local_page(subpage);
6929 if (!allow_pagefault)
6930 pagefault_disable();
6931 rc = copy_from_user(kaddr, usr_src + i * PAGE_SIZE, PAGE_SIZE);
6932 if (!allow_pagefault)
6933 pagefault_enable();
6934 kunmap_local(kaddr);
6935
6936 ret_val -= (PAGE_SIZE - rc);
6937 if (rc)
6938 break;
6939
6940 flush_dcache_page(subpage);
6941
6942 cond_resched();
6943 }
6944 return ret_val;
6945}
6946#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
6947
6948#if defined(CONFIG_SPLIT_PTE_PTLOCKS) && ALLOC_SPLIT_PTLOCKS
6949
6950static struct kmem_cache *page_ptl_cachep;
6951
6952void __init ptlock_cache_init(void)
6953{
6954 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
6955 SLAB_PANIC, NULL);
6956}
6957
6958bool ptlock_alloc(struct ptdesc *ptdesc)
6959{
6960 spinlock_t *ptl;
6961
6962 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
6963 if (!ptl)
6964 return false;
6965 ptdesc->ptl = ptl;
6966 return true;
6967}
6968
6969void ptlock_free(struct ptdesc *ptdesc)
6970{
6971 kmem_cache_free(page_ptl_cachep, ptdesc->ptl);
6972}
6973#endif
6974
6975void vma_pgtable_walk_begin(struct vm_area_struct *vma)
6976{
6977 if (is_vm_hugetlb_page(vma))
6978 hugetlb_vma_lock_read(vma);
6979}
6980
6981void vma_pgtable_walk_end(struct vm_area_struct *vma)
6982{
6983 if (is_vm_hugetlb_page(vma))
6984 hugetlb_vma_unlock_read(vma);
6985}