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1
2// SPDX-License-Identifier: GPL-2.0-only
3/*
4 * linux/mm/memory.c
5 *
6 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
7 */
8
9/*
10 * demand-loading started 01.12.91 - seems it is high on the list of
11 * things wanted, and it should be easy to implement. - Linus
12 */
13
14/*
15 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
16 * pages started 02.12.91, seems to work. - Linus.
17 *
18 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
19 * would have taken more than the 6M I have free, but it worked well as
20 * far as I could see.
21 *
22 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
23 */
24
25/*
26 * Real VM (paging to/from disk) started 18.12.91. Much more work and
27 * thought has to go into this. Oh, well..
28 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
29 * Found it. Everything seems to work now.
30 * 20.12.91 - Ok, making the swap-device changeable like the root.
31 */
32
33/*
34 * 05.04.94 - Multi-page memory management added for v1.1.
35 * Idea by Alex Bligh (alex@cconcepts.co.uk)
36 *
37 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
38 * (Gerhard.Wichert@pdb.siemens.de)
39 *
40 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
41 */
42
43#include <linux/kernel_stat.h>
44#include <linux/mm.h>
45#include <linux/mm_inline.h>
46#include <linux/sched/mm.h>
47#include <linux/sched/coredump.h>
48#include <linux/sched/numa_balancing.h>
49#include <linux/sched/task.h>
50#include <linux/hugetlb.h>
51#include <linux/mman.h>
52#include <linux/swap.h>
53#include <linux/highmem.h>
54#include <linux/pagemap.h>
55#include <linux/memremap.h>
56#include <linux/kmsan.h>
57#include <linux/ksm.h>
58#include <linux/rmap.h>
59#include <linux/export.h>
60#include <linux/delayacct.h>
61#include <linux/init.h>
62#include <linux/pfn_t.h>
63#include <linux/writeback.h>
64#include <linux/memcontrol.h>
65#include <linux/mmu_notifier.h>
66#include <linux/swapops.h>
67#include <linux/elf.h>
68#include <linux/gfp.h>
69#include <linux/migrate.h>
70#include <linux/string.h>
71#include <linux/memory-tiers.h>
72#include <linux/debugfs.h>
73#include <linux/userfaultfd_k.h>
74#include <linux/dax.h>
75#include <linux/oom.h>
76#include <linux/numa.h>
77#include <linux/perf_event.h>
78#include <linux/ptrace.h>
79#include <linux/vmalloc.h>
80#include <linux/sched/sysctl.h>
81
82#include <trace/events/kmem.h>
83
84#include <asm/io.h>
85#include <asm/mmu_context.h>
86#include <asm/pgalloc.h>
87#include <linux/uaccess.h>
88#include <asm/tlb.h>
89#include <asm/tlbflush.h>
90
91#include "pgalloc-track.h"
92#include "internal.h"
93#include "swap.h"
94
95#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
96#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
97#endif
98
99#ifndef CONFIG_NUMA
100unsigned long max_mapnr;
101EXPORT_SYMBOL(max_mapnr);
102
103struct page *mem_map;
104EXPORT_SYMBOL(mem_map);
105#endif
106
107static vm_fault_t do_fault(struct vm_fault *vmf);
108static vm_fault_t do_anonymous_page(struct vm_fault *vmf);
109static bool vmf_pte_changed(struct vm_fault *vmf);
110
111/*
112 * Return true if the original pte was a uffd-wp pte marker (so the pte was
113 * wr-protected).
114 */
115static bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf)
116{
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 do {
367 unsigned long addr = vma->vm_start;
368 struct vm_area_struct *next;
369
370 /*
371 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
372 * be 0. This will underflow and is okay.
373 */
374 next = mas_find(mas, ceiling - 1);
375 if (unlikely(xa_is_zero(next)))
376 next = NULL;
377
378 /*
379 * Hide vma from rmap and truncate_pagecache before freeing
380 * pgtables
381 */
382 if (mm_wr_locked)
383 vma_start_write(vma);
384 unlink_anon_vmas(vma);
385 unlink_file_vma(vma);
386
387 if (is_vm_hugetlb_page(vma)) {
388 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
389 floor, next ? next->vm_start : ceiling);
390 } else {
391 /*
392 * Optimization: gather nearby vmas into one call down
393 */
394 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
395 && !is_vm_hugetlb_page(next)) {
396 vma = next;
397 next = mas_find(mas, ceiling - 1);
398 if (unlikely(xa_is_zero(next)))
399 next = NULL;
400 if (mm_wr_locked)
401 vma_start_write(vma);
402 unlink_anon_vmas(vma);
403 unlink_file_vma(vma);
404 }
405 free_pgd_range(tlb, addr, vma->vm_end,
406 floor, next ? next->vm_start : ceiling);
407 }
408 vma = next;
409 } while (vma);
410}
411
412void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
413{
414 spinlock_t *ptl = pmd_lock(mm, pmd);
415
416 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
417 mm_inc_nr_ptes(mm);
418 /*
419 * Ensure all pte setup (eg. pte page lock and page clearing) are
420 * visible before the pte is made visible to other CPUs by being
421 * put into page tables.
422 *
423 * The other side of the story is the pointer chasing in the page
424 * table walking code (when walking the page table without locking;
425 * ie. most of the time). Fortunately, these data accesses consist
426 * of a chain of data-dependent loads, meaning most CPUs (alpha
427 * being the notable exception) will already guarantee loads are
428 * seen in-order. See the alpha page table accessors for the
429 * smp_rmb() barriers in page table walking code.
430 */
431 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
432 pmd_populate(mm, pmd, *pte);
433 *pte = NULL;
434 }
435 spin_unlock(ptl);
436}
437
438int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
439{
440 pgtable_t new = pte_alloc_one(mm);
441 if (!new)
442 return -ENOMEM;
443
444 pmd_install(mm, pmd, &new);
445 if (new)
446 pte_free(mm, new);
447 return 0;
448}
449
450int __pte_alloc_kernel(pmd_t *pmd)
451{
452 pte_t *new = pte_alloc_one_kernel(&init_mm);
453 if (!new)
454 return -ENOMEM;
455
456 spin_lock(&init_mm.page_table_lock);
457 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
458 smp_wmb(); /* See comment in pmd_install() */
459 pmd_populate_kernel(&init_mm, pmd, new);
460 new = NULL;
461 }
462 spin_unlock(&init_mm.page_table_lock);
463 if (new)
464 pte_free_kernel(&init_mm, new);
465 return 0;
466}
467
468static inline void init_rss_vec(int *rss)
469{
470 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
471}
472
473static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
474{
475 int i;
476
477 for (i = 0; i < NR_MM_COUNTERS; i++)
478 if (rss[i])
479 add_mm_counter(mm, i, rss[i]);
480}
481
482/*
483 * This function is called to print an error when a bad pte
484 * is found. For example, we might have a PFN-mapped pte in
485 * a region that doesn't allow it.
486 *
487 * The calling function must still handle the error.
488 */
489static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
490 pte_t pte, struct page *page)
491{
492 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
493 p4d_t *p4d = p4d_offset(pgd, addr);
494 pud_t *pud = pud_offset(p4d, addr);
495 pmd_t *pmd = pmd_offset(pud, addr);
496 struct address_space *mapping;
497 pgoff_t index;
498 static unsigned long resume;
499 static unsigned long nr_shown;
500 static unsigned long nr_unshown;
501
502 /*
503 * Allow a burst of 60 reports, then keep quiet for that minute;
504 * or allow a steady drip of one report per second.
505 */
506 if (nr_shown == 60) {
507 if (time_before(jiffies, resume)) {
508 nr_unshown++;
509 return;
510 }
511 if (nr_unshown) {
512 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
513 nr_unshown);
514 nr_unshown = 0;
515 }
516 nr_shown = 0;
517 }
518 if (nr_shown++ == 0)
519 resume = jiffies + 60 * HZ;
520
521 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
522 index = linear_page_index(vma, addr);
523
524 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
525 current->comm,
526 (long long)pte_val(pte), (long long)pmd_val(*pmd));
527 if (page)
528 dump_page(page, "bad pte");
529 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
530 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
531 pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
532 vma->vm_file,
533 vma->vm_ops ? vma->vm_ops->fault : NULL,
534 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
535 mapping ? mapping->a_ops->read_folio : NULL);
536 dump_stack();
537 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
538}
539
540/*
541 * vm_normal_page -- This function gets the "struct page" associated with a pte.
542 *
543 * "Special" mappings do not wish to be associated with a "struct page" (either
544 * it doesn't exist, or it exists but they don't want to touch it). In this
545 * case, NULL is returned here. "Normal" mappings do have a struct page.
546 *
547 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
548 * pte bit, in which case this function is trivial. Secondly, an architecture
549 * may not have a spare pte bit, which requires a more complicated scheme,
550 * described below.
551 *
552 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
553 * special mapping (even if there are underlying and valid "struct pages").
554 * COWed pages of a VM_PFNMAP are always normal.
555 *
556 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
557 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
558 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
559 * mapping will always honor the rule
560 *
561 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
562 *
563 * And for normal mappings this is false.
564 *
565 * This restricts such mappings to be a linear translation from virtual address
566 * to pfn. To get around this restriction, we allow arbitrary mappings so long
567 * as the vma is not a COW mapping; in that case, we know that all ptes are
568 * special (because none can have been COWed).
569 *
570 *
571 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
572 *
573 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
574 * page" backing, however the difference is that _all_ pages with a struct
575 * page (that is, those where pfn_valid is true) are refcounted and considered
576 * normal pages by the VM. The disadvantage is that pages are refcounted
577 * (which can be slower and simply not an option for some PFNMAP users). The
578 * advantage is that we don't have to follow the strict linearity rule of
579 * PFNMAP mappings in order to support COWable mappings.
580 *
581 */
582struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
583 pte_t pte)
584{
585 unsigned long pfn = pte_pfn(pte);
586
587 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
588 if (likely(!pte_special(pte)))
589 goto check_pfn;
590 if (vma->vm_ops && vma->vm_ops->find_special_page)
591 return vma->vm_ops->find_special_page(vma, addr);
592 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
593 return NULL;
594 if (is_zero_pfn(pfn))
595 return NULL;
596 if (pte_devmap(pte))
597 /*
598 * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
599 * and will have refcounts incremented on their struct pages
600 * when they are inserted into PTEs, thus they are safe to
601 * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
602 * do not have refcounts. Example of legacy ZONE_DEVICE is
603 * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
604 */
605 return NULL;
606
607 print_bad_pte(vma, addr, pte, NULL);
608 return NULL;
609 }
610
611 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
612
613 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
614 if (vma->vm_flags & VM_MIXEDMAP) {
615 if (!pfn_valid(pfn))
616 return NULL;
617 goto out;
618 } else {
619 unsigned long off;
620 off = (addr - vma->vm_start) >> PAGE_SHIFT;
621 if (pfn == vma->vm_pgoff + off)
622 return NULL;
623 if (!is_cow_mapping(vma->vm_flags))
624 return NULL;
625 }
626 }
627
628 if (is_zero_pfn(pfn))
629 return NULL;
630
631check_pfn:
632 if (unlikely(pfn > highest_memmap_pfn)) {
633 print_bad_pte(vma, addr, pte, NULL);
634 return NULL;
635 }
636
637 /*
638 * NOTE! We still have PageReserved() pages in the page tables.
639 * eg. VDSO mappings can cause them to exist.
640 */
641out:
642 return pfn_to_page(pfn);
643}
644
645struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr,
646 pte_t pte)
647{
648 struct page *page = vm_normal_page(vma, addr, pte);
649
650 if (page)
651 return page_folio(page);
652 return NULL;
653}
654
655#ifdef CONFIG_TRANSPARENT_HUGEPAGE
656struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
657 pmd_t pmd)
658{
659 unsigned long pfn = pmd_pfn(pmd);
660
661 /*
662 * There is no pmd_special() but there may be special pmds, e.g.
663 * in a direct-access (dax) mapping, so let's just replicate the
664 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
665 */
666 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
667 if (vma->vm_flags & VM_MIXEDMAP) {
668 if (!pfn_valid(pfn))
669 return NULL;
670 goto out;
671 } else {
672 unsigned long off;
673 off = (addr - vma->vm_start) >> PAGE_SHIFT;
674 if (pfn == vma->vm_pgoff + off)
675 return NULL;
676 if (!is_cow_mapping(vma->vm_flags))
677 return NULL;
678 }
679 }
680
681 if (pmd_devmap(pmd))
682 return NULL;
683 if (is_huge_zero_pmd(pmd))
684 return NULL;
685 if (unlikely(pfn > highest_memmap_pfn))
686 return NULL;
687
688 /*
689 * NOTE! We still have PageReserved() pages in the page tables.
690 * eg. VDSO mappings can cause them to exist.
691 */
692out:
693 return pfn_to_page(pfn);
694}
695
696struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma,
697 unsigned long addr, pmd_t pmd)
698{
699 struct page *page = vm_normal_page_pmd(vma, addr, pmd);
700
701 if (page)
702 return page_folio(page);
703 return NULL;
704}
705#endif
706
707static void restore_exclusive_pte(struct vm_area_struct *vma,
708 struct page *page, unsigned long address,
709 pte_t *ptep)
710{
711 struct folio *folio = page_folio(page);
712 pte_t orig_pte;
713 pte_t pte;
714 swp_entry_t entry;
715
716 orig_pte = ptep_get(ptep);
717 pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
718 if (pte_swp_soft_dirty(orig_pte))
719 pte = pte_mksoft_dirty(pte);
720
721 entry = pte_to_swp_entry(orig_pte);
722 if (pte_swp_uffd_wp(orig_pte))
723 pte = pte_mkuffd_wp(pte);
724 else if (is_writable_device_exclusive_entry(entry))
725 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
726
727 VM_BUG_ON_FOLIO(pte_write(pte) && (!folio_test_anon(folio) &&
728 PageAnonExclusive(page)), folio);
729
730 /*
731 * No need to take a page reference as one was already
732 * created when the swap entry was made.
733 */
734 if (folio_test_anon(folio))
735 folio_add_anon_rmap_pte(folio, page, vma, address, RMAP_NONE);
736 else
737 /*
738 * Currently device exclusive access only supports anonymous
739 * memory so the entry shouldn't point to a filebacked page.
740 */
741 WARN_ON_ONCE(1);
742
743 set_pte_at(vma->vm_mm, address, ptep, pte);
744
745 /*
746 * No need to invalidate - it was non-present before. However
747 * secondary CPUs may have mappings that need invalidating.
748 */
749 update_mmu_cache(vma, address, ptep);
750}
751
752/*
753 * Tries to restore an exclusive pte if the page lock can be acquired without
754 * sleeping.
755 */
756static int
757try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
758 unsigned long addr)
759{
760 swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte));
761 struct page *page = pfn_swap_entry_to_page(entry);
762
763 if (trylock_page(page)) {
764 restore_exclusive_pte(vma, page, addr, src_pte);
765 unlock_page(page);
766 return 0;
767 }
768
769 return -EBUSY;
770}
771
772/*
773 * copy one vm_area from one task to the other. Assumes the page tables
774 * already present in the new task to be cleared in the whole range
775 * covered by this vma.
776 */
777
778static unsigned long
779copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
780 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
781 struct vm_area_struct *src_vma, unsigned long addr, int *rss)
782{
783 unsigned long vm_flags = dst_vma->vm_flags;
784 pte_t orig_pte = ptep_get(src_pte);
785 pte_t pte = orig_pte;
786 struct folio *folio;
787 struct page *page;
788 swp_entry_t entry = pte_to_swp_entry(orig_pte);
789
790 if (likely(!non_swap_entry(entry))) {
791 if (swap_duplicate(entry) < 0)
792 return -EIO;
793
794 /* make sure dst_mm is on swapoff's mmlist. */
795 if (unlikely(list_empty(&dst_mm->mmlist))) {
796 spin_lock(&mmlist_lock);
797 if (list_empty(&dst_mm->mmlist))
798 list_add(&dst_mm->mmlist,
799 &src_mm->mmlist);
800 spin_unlock(&mmlist_lock);
801 }
802 /* Mark the swap entry as shared. */
803 if (pte_swp_exclusive(orig_pte)) {
804 pte = pte_swp_clear_exclusive(orig_pte);
805 set_pte_at(src_mm, addr, src_pte, pte);
806 }
807 rss[MM_SWAPENTS]++;
808 } else if (is_migration_entry(entry)) {
809 page = pfn_swap_entry_to_page(entry);
810
811 rss[mm_counter(page)]++;
812
813 if (!is_readable_migration_entry(entry) &&
814 is_cow_mapping(vm_flags)) {
815 /*
816 * COW mappings require pages in both parent and child
817 * to be set to read. A previously exclusive entry is
818 * now shared.
819 */
820 entry = make_readable_migration_entry(
821 swp_offset(entry));
822 pte = swp_entry_to_pte(entry);
823 if (pte_swp_soft_dirty(orig_pte))
824 pte = pte_swp_mksoft_dirty(pte);
825 if (pte_swp_uffd_wp(orig_pte))
826 pte = pte_swp_mkuffd_wp(pte);
827 set_pte_at(src_mm, addr, src_pte, pte);
828 }
829 } else if (is_device_private_entry(entry)) {
830 page = pfn_swap_entry_to_page(entry);
831 folio = page_folio(page);
832
833 /*
834 * Update rss count even for unaddressable pages, as
835 * they should treated just like normal pages in this
836 * respect.
837 *
838 * We will likely want to have some new rss counters
839 * for unaddressable pages, at some point. But for now
840 * keep things as they are.
841 */
842 folio_get(folio);
843 rss[mm_counter(page)]++;
844 /* Cannot fail as these pages cannot get pinned. */
845 folio_try_dup_anon_rmap_pte(folio, page, src_vma);
846
847 /*
848 * We do not preserve soft-dirty information, because so
849 * far, checkpoint/restore is the only feature that
850 * requires that. And checkpoint/restore does not work
851 * when a device driver is involved (you cannot easily
852 * save and restore device driver state).
853 */
854 if (is_writable_device_private_entry(entry) &&
855 is_cow_mapping(vm_flags)) {
856 entry = make_readable_device_private_entry(
857 swp_offset(entry));
858 pte = swp_entry_to_pte(entry);
859 if (pte_swp_uffd_wp(orig_pte))
860 pte = pte_swp_mkuffd_wp(pte);
861 set_pte_at(src_mm, addr, src_pte, pte);
862 }
863 } else if (is_device_exclusive_entry(entry)) {
864 /*
865 * Make device exclusive entries present by restoring the
866 * original entry then copying as for a present pte. Device
867 * exclusive entries currently only support private writable
868 * (ie. COW) mappings.
869 */
870 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
871 if (try_restore_exclusive_pte(src_pte, src_vma, addr))
872 return -EBUSY;
873 return -ENOENT;
874 } else if (is_pte_marker_entry(entry)) {
875 pte_marker marker = copy_pte_marker(entry, dst_vma);
876
877 if (marker)
878 set_pte_at(dst_mm, addr, dst_pte,
879 make_pte_marker(marker));
880 return 0;
881 }
882 if (!userfaultfd_wp(dst_vma))
883 pte = pte_swp_clear_uffd_wp(pte);
884 set_pte_at(dst_mm, addr, dst_pte, pte);
885 return 0;
886}
887
888/*
889 * Copy a present and normal page.
890 *
891 * NOTE! The usual case is that this isn't required;
892 * instead, the caller can just increase the page refcount
893 * and re-use the pte the traditional way.
894 *
895 * And if we need a pre-allocated page but don't yet have
896 * one, return a negative error to let the preallocation
897 * code know so that it can do so outside the page table
898 * lock.
899 */
900static inline int
901copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
902 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
903 struct folio **prealloc, struct page *page)
904{
905 struct folio *new_folio;
906 pte_t pte;
907
908 new_folio = *prealloc;
909 if (!new_folio)
910 return -EAGAIN;
911
912 /*
913 * We have a prealloc page, all good! Take it
914 * over and copy the page & arm it.
915 */
916 *prealloc = NULL;
917 copy_user_highpage(&new_folio->page, page, addr, src_vma);
918 __folio_mark_uptodate(new_folio);
919 folio_add_new_anon_rmap(new_folio, dst_vma, addr);
920 folio_add_lru_vma(new_folio, dst_vma);
921 rss[MM_ANONPAGES]++;
922
923 /* All done, just insert the new page copy in the child */
924 pte = mk_pte(&new_folio->page, dst_vma->vm_page_prot);
925 pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
926 if (userfaultfd_pte_wp(dst_vma, ptep_get(src_pte)))
927 /* Uffd-wp needs to be delivered to dest pte as well */
928 pte = pte_mkuffd_wp(pte);
929 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
930 return 0;
931}
932
933/*
934 * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
935 * is required to copy this pte.
936 */
937static inline int
938copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
939 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
940 struct folio **prealloc)
941{
942 struct mm_struct *src_mm = src_vma->vm_mm;
943 unsigned long vm_flags = src_vma->vm_flags;
944 pte_t pte = ptep_get(src_pte);
945 struct page *page;
946 struct folio *folio;
947
948 page = vm_normal_page(src_vma, addr, pte);
949 if (page)
950 folio = page_folio(page);
951 if (page && folio_test_anon(folio)) {
952 /*
953 * If this page may have been pinned by the parent process,
954 * copy the page immediately for the child so that we'll always
955 * guarantee the pinned page won't be randomly replaced in the
956 * future.
957 */
958 folio_get(folio);
959 if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, src_vma))) {
960 /* Page may be pinned, we have to copy. */
961 folio_put(folio);
962 return copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
963 addr, rss, prealloc, page);
964 }
965 rss[MM_ANONPAGES]++;
966 } else if (page) {
967 folio_get(folio);
968 folio_dup_file_rmap_pte(folio, page);
969 rss[mm_counter_file(page)]++;
970 }
971
972 /*
973 * If it's a COW mapping, write protect it both
974 * in the parent and the child
975 */
976 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
977 ptep_set_wrprotect(src_mm, addr, src_pte);
978 pte = pte_wrprotect(pte);
979 }
980 VM_BUG_ON(page && folio_test_anon(folio) && PageAnonExclusive(page));
981
982 /*
983 * If it's a shared mapping, mark it clean in
984 * the child
985 */
986 if (vm_flags & VM_SHARED)
987 pte = pte_mkclean(pte);
988 pte = pte_mkold(pte);
989
990 if (!userfaultfd_wp(dst_vma))
991 pte = pte_clear_uffd_wp(pte);
992
993 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
994 return 0;
995}
996
997static inline struct folio *folio_prealloc(struct mm_struct *src_mm,
998 struct vm_area_struct *vma, unsigned long addr, bool need_zero)
999{
1000 struct folio *new_folio;
1001
1002 if (need_zero)
1003 new_folio = vma_alloc_zeroed_movable_folio(vma, addr);
1004 else
1005 new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma,
1006 addr, false);
1007
1008 if (!new_folio)
1009 return NULL;
1010
1011 if (mem_cgroup_charge(new_folio, src_mm, GFP_KERNEL)) {
1012 folio_put(new_folio);
1013 return NULL;
1014 }
1015 folio_throttle_swaprate(new_folio, GFP_KERNEL);
1016
1017 return new_folio;
1018}
1019
1020static int
1021copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1022 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1023 unsigned long end)
1024{
1025 struct mm_struct *dst_mm = dst_vma->vm_mm;
1026 struct mm_struct *src_mm = src_vma->vm_mm;
1027 pte_t *orig_src_pte, *orig_dst_pte;
1028 pte_t *src_pte, *dst_pte;
1029 pte_t ptent;
1030 spinlock_t *src_ptl, *dst_ptl;
1031 int progress, ret = 0;
1032 int rss[NR_MM_COUNTERS];
1033 swp_entry_t entry = (swp_entry_t){0};
1034 struct folio *prealloc = NULL;
1035
1036again:
1037 progress = 0;
1038 init_rss_vec(rss);
1039
1040 /*
1041 * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the
1042 * error handling here, assume that exclusive mmap_lock on dst and src
1043 * protects anon from unexpected THP transitions; with shmem and file
1044 * protected by mmap_lock-less collapse skipping areas with anon_vma
1045 * (whereas vma_needs_copy() skips areas without anon_vma). A rework
1046 * can remove such assumptions later, but this is good enough for now.
1047 */
1048 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1049 if (!dst_pte) {
1050 ret = -ENOMEM;
1051 goto out;
1052 }
1053 src_pte = pte_offset_map_nolock(src_mm, src_pmd, addr, &src_ptl);
1054 if (!src_pte) {
1055 pte_unmap_unlock(dst_pte, dst_ptl);
1056 /* ret == 0 */
1057 goto out;
1058 }
1059 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1060 orig_src_pte = src_pte;
1061 orig_dst_pte = dst_pte;
1062 arch_enter_lazy_mmu_mode();
1063
1064 do {
1065 /*
1066 * We are holding two locks at this point - either of them
1067 * could generate latencies in another task on another CPU.
1068 */
1069 if (progress >= 32) {
1070 progress = 0;
1071 if (need_resched() ||
1072 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1073 break;
1074 }
1075 ptent = ptep_get(src_pte);
1076 if (pte_none(ptent)) {
1077 progress++;
1078 continue;
1079 }
1080 if (unlikely(!pte_present(ptent))) {
1081 ret = copy_nonpresent_pte(dst_mm, src_mm,
1082 dst_pte, src_pte,
1083 dst_vma, src_vma,
1084 addr, rss);
1085 if (ret == -EIO) {
1086 entry = pte_to_swp_entry(ptep_get(src_pte));
1087 break;
1088 } else if (ret == -EBUSY) {
1089 break;
1090 } else if (!ret) {
1091 progress += 8;
1092 continue;
1093 }
1094
1095 /*
1096 * Device exclusive entry restored, continue by copying
1097 * the now present pte.
1098 */
1099 WARN_ON_ONCE(ret != -ENOENT);
1100 }
1101 /* copy_present_pte() will clear `*prealloc' if consumed */
1102 ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
1103 addr, rss, &prealloc);
1104 /*
1105 * If we need a pre-allocated page for this pte, drop the
1106 * locks, allocate, and try again.
1107 */
1108 if (unlikely(ret == -EAGAIN))
1109 break;
1110 if (unlikely(prealloc)) {
1111 /*
1112 * pre-alloc page cannot be reused by next time so as
1113 * to strictly follow mempolicy (e.g., alloc_page_vma()
1114 * will allocate page according to address). This
1115 * could only happen if one pinned pte changed.
1116 */
1117 folio_put(prealloc);
1118 prealloc = NULL;
1119 }
1120 progress += 8;
1121 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1122
1123 arch_leave_lazy_mmu_mode();
1124 pte_unmap_unlock(orig_src_pte, src_ptl);
1125 add_mm_rss_vec(dst_mm, rss);
1126 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1127 cond_resched();
1128
1129 if (ret == -EIO) {
1130 VM_WARN_ON_ONCE(!entry.val);
1131 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1132 ret = -ENOMEM;
1133 goto out;
1134 }
1135 entry.val = 0;
1136 } else if (ret == -EBUSY) {
1137 goto out;
1138 } else if (ret == -EAGAIN) {
1139 prealloc = folio_prealloc(src_mm, src_vma, addr, false);
1140 if (!prealloc)
1141 return -ENOMEM;
1142 } else if (ret) {
1143 VM_WARN_ON_ONCE(1);
1144 }
1145
1146 /* We've captured and resolved the error. Reset, try again. */
1147 ret = 0;
1148
1149 if (addr != end)
1150 goto again;
1151out:
1152 if (unlikely(prealloc))
1153 folio_put(prealloc);
1154 return ret;
1155}
1156
1157static inline int
1158copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1159 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1160 unsigned long end)
1161{
1162 struct mm_struct *dst_mm = dst_vma->vm_mm;
1163 struct mm_struct *src_mm = src_vma->vm_mm;
1164 pmd_t *src_pmd, *dst_pmd;
1165 unsigned long next;
1166
1167 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1168 if (!dst_pmd)
1169 return -ENOMEM;
1170 src_pmd = pmd_offset(src_pud, addr);
1171 do {
1172 next = pmd_addr_end(addr, end);
1173 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1174 || pmd_devmap(*src_pmd)) {
1175 int err;
1176 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1177 err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1178 addr, dst_vma, src_vma);
1179 if (err == -ENOMEM)
1180 return -ENOMEM;
1181 if (!err)
1182 continue;
1183 /* fall through */
1184 }
1185 if (pmd_none_or_clear_bad(src_pmd))
1186 continue;
1187 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1188 addr, next))
1189 return -ENOMEM;
1190 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1191 return 0;
1192}
1193
1194static inline int
1195copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1196 p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1197 unsigned long end)
1198{
1199 struct mm_struct *dst_mm = dst_vma->vm_mm;
1200 struct mm_struct *src_mm = src_vma->vm_mm;
1201 pud_t *src_pud, *dst_pud;
1202 unsigned long next;
1203
1204 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1205 if (!dst_pud)
1206 return -ENOMEM;
1207 src_pud = pud_offset(src_p4d, addr);
1208 do {
1209 next = pud_addr_end(addr, end);
1210 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1211 int err;
1212
1213 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1214 err = copy_huge_pud(dst_mm, src_mm,
1215 dst_pud, src_pud, addr, src_vma);
1216 if (err == -ENOMEM)
1217 return -ENOMEM;
1218 if (!err)
1219 continue;
1220 /* fall through */
1221 }
1222 if (pud_none_or_clear_bad(src_pud))
1223 continue;
1224 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1225 addr, next))
1226 return -ENOMEM;
1227 } while (dst_pud++, src_pud++, addr = next, addr != end);
1228 return 0;
1229}
1230
1231static inline int
1232copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1233 pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1234 unsigned long end)
1235{
1236 struct mm_struct *dst_mm = dst_vma->vm_mm;
1237 p4d_t *src_p4d, *dst_p4d;
1238 unsigned long next;
1239
1240 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1241 if (!dst_p4d)
1242 return -ENOMEM;
1243 src_p4d = p4d_offset(src_pgd, addr);
1244 do {
1245 next = p4d_addr_end(addr, end);
1246 if (p4d_none_or_clear_bad(src_p4d))
1247 continue;
1248 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1249 addr, next))
1250 return -ENOMEM;
1251 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1252 return 0;
1253}
1254
1255/*
1256 * Return true if the vma needs to copy the pgtable during this fork(). Return
1257 * false when we can speed up fork() by allowing lazy page faults later until
1258 * when the child accesses the memory range.
1259 */
1260static bool
1261vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1262{
1263 /*
1264 * Always copy pgtables when dst_vma has uffd-wp enabled even if it's
1265 * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable
1266 * contains uffd-wp protection information, that's something we can't
1267 * retrieve from page cache, and skip copying will lose those info.
1268 */
1269 if (userfaultfd_wp(dst_vma))
1270 return true;
1271
1272 if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
1273 return true;
1274
1275 if (src_vma->anon_vma)
1276 return true;
1277
1278 /*
1279 * Don't copy ptes where a page fault will fill them correctly. Fork
1280 * becomes much lighter when there are big shared or private readonly
1281 * mappings. The tradeoff is that copy_page_range is more efficient
1282 * than faulting.
1283 */
1284 return false;
1285}
1286
1287int
1288copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1289{
1290 pgd_t *src_pgd, *dst_pgd;
1291 unsigned long next;
1292 unsigned long addr = src_vma->vm_start;
1293 unsigned long end = src_vma->vm_end;
1294 struct mm_struct *dst_mm = dst_vma->vm_mm;
1295 struct mm_struct *src_mm = src_vma->vm_mm;
1296 struct mmu_notifier_range range;
1297 bool is_cow;
1298 int ret;
1299
1300 if (!vma_needs_copy(dst_vma, src_vma))
1301 return 0;
1302
1303 if (is_vm_hugetlb_page(src_vma))
1304 return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma);
1305
1306 if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1307 /*
1308 * We do not free on error cases below as remove_vma
1309 * gets called on error from higher level routine
1310 */
1311 ret = track_pfn_copy(src_vma);
1312 if (ret)
1313 return ret;
1314 }
1315
1316 /*
1317 * We need to invalidate the secondary MMU mappings only when
1318 * there could be a permission downgrade on the ptes of the
1319 * parent mm. And a permission downgrade will only happen if
1320 * is_cow_mapping() returns true.
1321 */
1322 is_cow = is_cow_mapping(src_vma->vm_flags);
1323
1324 if (is_cow) {
1325 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1326 0, src_mm, addr, end);
1327 mmu_notifier_invalidate_range_start(&range);
1328 /*
1329 * Disabling preemption is not needed for the write side, as
1330 * the read side doesn't spin, but goes to the mmap_lock.
1331 *
1332 * Use the raw variant of the seqcount_t write API to avoid
1333 * lockdep complaining about preemptibility.
1334 */
1335 vma_assert_write_locked(src_vma);
1336 raw_write_seqcount_begin(&src_mm->write_protect_seq);
1337 }
1338
1339 ret = 0;
1340 dst_pgd = pgd_offset(dst_mm, addr);
1341 src_pgd = pgd_offset(src_mm, addr);
1342 do {
1343 next = pgd_addr_end(addr, end);
1344 if (pgd_none_or_clear_bad(src_pgd))
1345 continue;
1346 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1347 addr, next))) {
1348 untrack_pfn_clear(dst_vma);
1349 ret = -ENOMEM;
1350 break;
1351 }
1352 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1353
1354 if (is_cow) {
1355 raw_write_seqcount_end(&src_mm->write_protect_seq);
1356 mmu_notifier_invalidate_range_end(&range);
1357 }
1358 return ret;
1359}
1360
1361/* Whether we should zap all COWed (private) pages too */
1362static inline bool should_zap_cows(struct zap_details *details)
1363{
1364 /* By default, zap all pages */
1365 if (!details)
1366 return true;
1367
1368 /* Or, we zap COWed pages only if the caller wants to */
1369 return details->even_cows;
1370}
1371
1372/* Decides whether we should zap this page with the page pointer specified */
1373static inline bool should_zap_page(struct zap_details *details, struct page *page)
1374{
1375 /* If we can make a decision without *page.. */
1376 if (should_zap_cows(details))
1377 return true;
1378
1379 /* E.g. the caller passes NULL for the case of a zero page */
1380 if (!page)
1381 return true;
1382
1383 /* Otherwise we should only zap non-anon pages */
1384 return !PageAnon(page);
1385}
1386
1387static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
1388{
1389 if (!details)
1390 return false;
1391
1392 return details->zap_flags & ZAP_FLAG_DROP_MARKER;
1393}
1394
1395/*
1396 * This function makes sure that we'll replace the none pte with an uffd-wp
1397 * swap special pte marker when necessary. Must be with the pgtable lock held.
1398 */
1399static inline void
1400zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
1401 unsigned long addr, pte_t *pte,
1402 struct zap_details *details, pte_t pteval)
1403{
1404 /* Zap on anonymous always means dropping everything */
1405 if (vma_is_anonymous(vma))
1406 return;
1407
1408 if (zap_drop_file_uffd_wp(details))
1409 return;
1410
1411 pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
1412}
1413
1414static unsigned long zap_pte_range(struct mmu_gather *tlb,
1415 struct vm_area_struct *vma, pmd_t *pmd,
1416 unsigned long addr, unsigned long end,
1417 struct zap_details *details)
1418{
1419 struct mm_struct *mm = tlb->mm;
1420 int force_flush = 0;
1421 int rss[NR_MM_COUNTERS];
1422 spinlock_t *ptl;
1423 pte_t *start_pte;
1424 pte_t *pte;
1425 swp_entry_t entry;
1426
1427 tlb_change_page_size(tlb, PAGE_SIZE);
1428 init_rss_vec(rss);
1429 start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1430 if (!pte)
1431 return addr;
1432
1433 flush_tlb_batched_pending(mm);
1434 arch_enter_lazy_mmu_mode();
1435 do {
1436 pte_t ptent = ptep_get(pte);
1437 struct folio *folio;
1438 struct page *page;
1439
1440 if (pte_none(ptent))
1441 continue;
1442
1443 if (need_resched())
1444 break;
1445
1446 if (pte_present(ptent)) {
1447 unsigned int delay_rmap;
1448
1449 page = vm_normal_page(vma, addr, ptent);
1450 if (unlikely(!should_zap_page(details, page)))
1451 continue;
1452 ptent = ptep_get_and_clear_full(mm, addr, pte,
1453 tlb->fullmm);
1454 arch_check_zapped_pte(vma, ptent);
1455 tlb_remove_tlb_entry(tlb, pte, addr);
1456 zap_install_uffd_wp_if_needed(vma, addr, pte, details,
1457 ptent);
1458 if (unlikely(!page)) {
1459 ksm_might_unmap_zero_page(mm, ptent);
1460 continue;
1461 }
1462
1463 folio = page_folio(page);
1464 delay_rmap = 0;
1465 if (!folio_test_anon(folio)) {
1466 if (pte_dirty(ptent)) {
1467 folio_mark_dirty(folio);
1468 if (tlb_delay_rmap(tlb)) {
1469 delay_rmap = 1;
1470 force_flush = 1;
1471 }
1472 }
1473 if (pte_young(ptent) && likely(vma_has_recency(vma)))
1474 folio_mark_accessed(folio);
1475 }
1476 rss[mm_counter(page)]--;
1477 if (!delay_rmap) {
1478 folio_remove_rmap_pte(folio, page, vma);
1479 if (unlikely(page_mapcount(page) < 0))
1480 print_bad_pte(vma, addr, ptent, page);
1481 }
1482 if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) {
1483 force_flush = 1;
1484 addr += PAGE_SIZE;
1485 break;
1486 }
1487 continue;
1488 }
1489
1490 entry = pte_to_swp_entry(ptent);
1491 if (is_device_private_entry(entry) ||
1492 is_device_exclusive_entry(entry)) {
1493 page = pfn_swap_entry_to_page(entry);
1494 folio = page_folio(page);
1495 if (unlikely(!should_zap_page(details, page)))
1496 continue;
1497 /*
1498 * Both device private/exclusive mappings should only
1499 * work with anonymous page so far, so we don't need to
1500 * consider uffd-wp bit when zap. For more information,
1501 * see zap_install_uffd_wp_if_needed().
1502 */
1503 WARN_ON_ONCE(!vma_is_anonymous(vma));
1504 rss[mm_counter(page)]--;
1505 if (is_device_private_entry(entry))
1506 folio_remove_rmap_pte(folio, page, vma);
1507 folio_put(folio);
1508 } else if (!non_swap_entry(entry)) {
1509 /* Genuine swap entry, hence a private anon page */
1510 if (!should_zap_cows(details))
1511 continue;
1512 rss[MM_SWAPENTS]--;
1513 if (unlikely(!free_swap_and_cache(entry)))
1514 print_bad_pte(vma, addr, ptent, NULL);
1515 } else if (is_migration_entry(entry)) {
1516 page = pfn_swap_entry_to_page(entry);
1517 if (!should_zap_page(details, page))
1518 continue;
1519 rss[mm_counter(page)]--;
1520 } else if (pte_marker_entry_uffd_wp(entry)) {
1521 /*
1522 * For anon: always drop the marker; for file: only
1523 * drop the marker if explicitly requested.
1524 */
1525 if (!vma_is_anonymous(vma) &&
1526 !zap_drop_file_uffd_wp(details))
1527 continue;
1528 } else if (is_hwpoison_entry(entry) ||
1529 is_poisoned_swp_entry(entry)) {
1530 if (!should_zap_cows(details))
1531 continue;
1532 } else {
1533 /* We should have covered all the swap entry types */
1534 pr_alert("unrecognized swap entry 0x%lx\n", entry.val);
1535 WARN_ON_ONCE(1);
1536 }
1537 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1538 zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent);
1539 } while (pte++, addr += PAGE_SIZE, addr != end);
1540
1541 add_mm_rss_vec(mm, rss);
1542 arch_leave_lazy_mmu_mode();
1543
1544 /* Do the actual TLB flush before dropping ptl */
1545 if (force_flush) {
1546 tlb_flush_mmu_tlbonly(tlb);
1547 tlb_flush_rmaps(tlb, vma);
1548 }
1549 pte_unmap_unlock(start_pte, ptl);
1550
1551 /*
1552 * If we forced a TLB flush (either due to running out of
1553 * batch buffers or because we needed to flush dirty TLB
1554 * entries before releasing the ptl), free the batched
1555 * memory too. Come back again if we didn't do everything.
1556 */
1557 if (force_flush)
1558 tlb_flush_mmu(tlb);
1559
1560 return addr;
1561}
1562
1563static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1564 struct vm_area_struct *vma, pud_t *pud,
1565 unsigned long addr, unsigned long end,
1566 struct zap_details *details)
1567{
1568 pmd_t *pmd;
1569 unsigned long next;
1570
1571 pmd = pmd_offset(pud, addr);
1572 do {
1573 next = pmd_addr_end(addr, end);
1574 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1575 if (next - addr != HPAGE_PMD_SIZE)
1576 __split_huge_pmd(vma, pmd, addr, false, NULL);
1577 else if (zap_huge_pmd(tlb, vma, pmd, addr)) {
1578 addr = next;
1579 continue;
1580 }
1581 /* fall through */
1582 } else if (details && details->single_folio &&
1583 folio_test_pmd_mappable(details->single_folio) &&
1584 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1585 spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1586 /*
1587 * Take and drop THP pmd lock so that we cannot return
1588 * prematurely, while zap_huge_pmd() has cleared *pmd,
1589 * but not yet decremented compound_mapcount().
1590 */
1591 spin_unlock(ptl);
1592 }
1593 if (pmd_none(*pmd)) {
1594 addr = next;
1595 continue;
1596 }
1597 addr = zap_pte_range(tlb, vma, pmd, addr, next, details);
1598 if (addr != next)
1599 pmd--;
1600 } while (pmd++, cond_resched(), addr != end);
1601
1602 return addr;
1603}
1604
1605static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1606 struct vm_area_struct *vma, p4d_t *p4d,
1607 unsigned long addr, unsigned long end,
1608 struct zap_details *details)
1609{
1610 pud_t *pud;
1611 unsigned long next;
1612
1613 pud = pud_offset(p4d, addr);
1614 do {
1615 next = pud_addr_end(addr, end);
1616 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1617 if (next - addr != HPAGE_PUD_SIZE) {
1618 mmap_assert_locked(tlb->mm);
1619 split_huge_pud(vma, pud, addr);
1620 } else if (zap_huge_pud(tlb, vma, pud, addr))
1621 goto next;
1622 /* fall through */
1623 }
1624 if (pud_none_or_clear_bad(pud))
1625 continue;
1626 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1627next:
1628 cond_resched();
1629 } while (pud++, addr = next, addr != end);
1630
1631 return addr;
1632}
1633
1634static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1635 struct vm_area_struct *vma, pgd_t *pgd,
1636 unsigned long addr, unsigned long end,
1637 struct zap_details *details)
1638{
1639 p4d_t *p4d;
1640 unsigned long next;
1641
1642 p4d = p4d_offset(pgd, addr);
1643 do {
1644 next = p4d_addr_end(addr, end);
1645 if (p4d_none_or_clear_bad(p4d))
1646 continue;
1647 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1648 } while (p4d++, addr = next, addr != end);
1649
1650 return addr;
1651}
1652
1653void unmap_page_range(struct mmu_gather *tlb,
1654 struct vm_area_struct *vma,
1655 unsigned long addr, unsigned long end,
1656 struct zap_details *details)
1657{
1658 pgd_t *pgd;
1659 unsigned long next;
1660
1661 BUG_ON(addr >= end);
1662 tlb_start_vma(tlb, vma);
1663 pgd = pgd_offset(vma->vm_mm, addr);
1664 do {
1665 next = pgd_addr_end(addr, end);
1666 if (pgd_none_or_clear_bad(pgd))
1667 continue;
1668 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1669 } while (pgd++, addr = next, addr != end);
1670 tlb_end_vma(tlb, vma);
1671}
1672
1673
1674static void unmap_single_vma(struct mmu_gather *tlb,
1675 struct vm_area_struct *vma, unsigned long start_addr,
1676 unsigned long end_addr,
1677 struct zap_details *details, bool mm_wr_locked)
1678{
1679 unsigned long start = max(vma->vm_start, start_addr);
1680 unsigned long end;
1681
1682 if (start >= vma->vm_end)
1683 return;
1684 end = min(vma->vm_end, end_addr);
1685 if (end <= vma->vm_start)
1686 return;
1687
1688 if (vma->vm_file)
1689 uprobe_munmap(vma, start, end);
1690
1691 if (unlikely(vma->vm_flags & VM_PFNMAP))
1692 untrack_pfn(vma, 0, 0, mm_wr_locked);
1693
1694 if (start != end) {
1695 if (unlikely(is_vm_hugetlb_page(vma))) {
1696 /*
1697 * It is undesirable to test vma->vm_file as it
1698 * should be non-null for valid hugetlb area.
1699 * However, vm_file will be NULL in the error
1700 * cleanup path of mmap_region. When
1701 * hugetlbfs ->mmap method fails,
1702 * mmap_region() nullifies vma->vm_file
1703 * before calling this function to clean up.
1704 * Since no pte has actually been setup, it is
1705 * safe to do nothing in this case.
1706 */
1707 if (vma->vm_file) {
1708 zap_flags_t zap_flags = details ?
1709 details->zap_flags : 0;
1710 __unmap_hugepage_range(tlb, vma, start, end,
1711 NULL, zap_flags);
1712 }
1713 } else
1714 unmap_page_range(tlb, vma, start, end, details);
1715 }
1716}
1717
1718/**
1719 * unmap_vmas - unmap a range of memory covered by a list of vma's
1720 * @tlb: address of the caller's struct mmu_gather
1721 * @mas: the maple state
1722 * @vma: the starting vma
1723 * @start_addr: virtual address at which to start unmapping
1724 * @end_addr: virtual address at which to end unmapping
1725 * @tree_end: The maximum index to check
1726 * @mm_wr_locked: lock flag
1727 *
1728 * Unmap all pages in the vma list.
1729 *
1730 * Only addresses between `start' and `end' will be unmapped.
1731 *
1732 * The VMA list must be sorted in ascending virtual address order.
1733 *
1734 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1735 * range after unmap_vmas() returns. So the only responsibility here is to
1736 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1737 * drops the lock and schedules.
1738 */
1739void unmap_vmas(struct mmu_gather *tlb, struct ma_state *mas,
1740 struct vm_area_struct *vma, unsigned long start_addr,
1741 unsigned long end_addr, unsigned long tree_end,
1742 bool mm_wr_locked)
1743{
1744 struct mmu_notifier_range range;
1745 struct zap_details details = {
1746 .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP,
1747 /* Careful - we need to zap private pages too! */
1748 .even_cows = true,
1749 };
1750
1751 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm,
1752 start_addr, end_addr);
1753 mmu_notifier_invalidate_range_start(&range);
1754 do {
1755 unsigned long start = start_addr;
1756 unsigned long end = end_addr;
1757 hugetlb_zap_begin(vma, &start, &end);
1758 unmap_single_vma(tlb, vma, start, end, &details,
1759 mm_wr_locked);
1760 hugetlb_zap_end(vma, &details);
1761 vma = mas_find(mas, tree_end - 1);
1762 } while (vma && likely(!xa_is_zero(vma)));
1763 mmu_notifier_invalidate_range_end(&range);
1764}
1765
1766/**
1767 * zap_page_range_single - remove user pages in a given range
1768 * @vma: vm_area_struct holding the applicable pages
1769 * @address: starting address of pages to zap
1770 * @size: number of bytes to zap
1771 * @details: details of shared cache invalidation
1772 *
1773 * The range must fit into one VMA.
1774 */
1775void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1776 unsigned long size, struct zap_details *details)
1777{
1778 const unsigned long end = address + size;
1779 struct mmu_notifier_range range;
1780 struct mmu_gather tlb;
1781
1782 lru_add_drain();
1783 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
1784 address, end);
1785 hugetlb_zap_begin(vma, &range.start, &range.end);
1786 tlb_gather_mmu(&tlb, vma->vm_mm);
1787 update_hiwater_rss(vma->vm_mm);
1788 mmu_notifier_invalidate_range_start(&range);
1789 /*
1790 * unmap 'address-end' not 'range.start-range.end' as range
1791 * could have been expanded for hugetlb pmd sharing.
1792 */
1793 unmap_single_vma(&tlb, vma, address, end, details, false);
1794 mmu_notifier_invalidate_range_end(&range);
1795 tlb_finish_mmu(&tlb);
1796 hugetlb_zap_end(vma, details);
1797}
1798
1799/**
1800 * zap_vma_ptes - remove ptes mapping the vma
1801 * @vma: vm_area_struct holding ptes to be zapped
1802 * @address: starting address of pages to zap
1803 * @size: number of bytes to zap
1804 *
1805 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1806 *
1807 * The entire address range must be fully contained within the vma.
1808 *
1809 */
1810void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1811 unsigned long size)
1812{
1813 if (!range_in_vma(vma, address, address + size) ||
1814 !(vma->vm_flags & VM_PFNMAP))
1815 return;
1816
1817 zap_page_range_single(vma, address, size, NULL);
1818}
1819EXPORT_SYMBOL_GPL(zap_vma_ptes);
1820
1821static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1822{
1823 pgd_t *pgd;
1824 p4d_t *p4d;
1825 pud_t *pud;
1826 pmd_t *pmd;
1827
1828 pgd = pgd_offset(mm, addr);
1829 p4d = p4d_alloc(mm, pgd, addr);
1830 if (!p4d)
1831 return NULL;
1832 pud = pud_alloc(mm, p4d, addr);
1833 if (!pud)
1834 return NULL;
1835 pmd = pmd_alloc(mm, pud, addr);
1836 if (!pmd)
1837 return NULL;
1838
1839 VM_BUG_ON(pmd_trans_huge(*pmd));
1840 return pmd;
1841}
1842
1843pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1844 spinlock_t **ptl)
1845{
1846 pmd_t *pmd = walk_to_pmd(mm, addr);
1847
1848 if (!pmd)
1849 return NULL;
1850 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1851}
1852
1853static int validate_page_before_insert(struct page *page)
1854{
1855 struct folio *folio = page_folio(page);
1856
1857 if (folio_test_anon(folio) || folio_test_slab(folio) ||
1858 page_has_type(page))
1859 return -EINVAL;
1860 flush_dcache_folio(folio);
1861 return 0;
1862}
1863
1864static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
1865 unsigned long addr, struct page *page, pgprot_t prot)
1866{
1867 struct folio *folio = page_folio(page);
1868
1869 if (!pte_none(ptep_get(pte)))
1870 return -EBUSY;
1871 /* Ok, finally just insert the thing.. */
1872 folio_get(folio);
1873 inc_mm_counter(vma->vm_mm, mm_counter_file(page));
1874 folio_add_file_rmap_pte(folio, page, vma);
1875 set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
1876 return 0;
1877}
1878
1879/*
1880 * This is the old fallback for page remapping.
1881 *
1882 * For historical reasons, it only allows reserved pages. Only
1883 * old drivers should use this, and they needed to mark their
1884 * pages reserved for the old functions anyway.
1885 */
1886static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1887 struct page *page, pgprot_t prot)
1888{
1889 int retval;
1890 pte_t *pte;
1891 spinlock_t *ptl;
1892
1893 retval = validate_page_before_insert(page);
1894 if (retval)
1895 goto out;
1896 retval = -ENOMEM;
1897 pte = get_locked_pte(vma->vm_mm, addr, &ptl);
1898 if (!pte)
1899 goto out;
1900 retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
1901 pte_unmap_unlock(pte, ptl);
1902out:
1903 return retval;
1904}
1905
1906static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
1907 unsigned long addr, struct page *page, pgprot_t prot)
1908{
1909 int err;
1910
1911 if (!page_count(page))
1912 return -EINVAL;
1913 err = validate_page_before_insert(page);
1914 if (err)
1915 return err;
1916 return insert_page_into_pte_locked(vma, pte, addr, page, prot);
1917}
1918
1919/* insert_pages() amortizes the cost of spinlock operations
1920 * when inserting pages in a loop.
1921 */
1922static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
1923 struct page **pages, unsigned long *num, pgprot_t prot)
1924{
1925 pmd_t *pmd = NULL;
1926 pte_t *start_pte, *pte;
1927 spinlock_t *pte_lock;
1928 struct mm_struct *const mm = vma->vm_mm;
1929 unsigned long curr_page_idx = 0;
1930 unsigned long remaining_pages_total = *num;
1931 unsigned long pages_to_write_in_pmd;
1932 int ret;
1933more:
1934 ret = -EFAULT;
1935 pmd = walk_to_pmd(mm, addr);
1936 if (!pmd)
1937 goto out;
1938
1939 pages_to_write_in_pmd = min_t(unsigned long,
1940 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
1941
1942 /* Allocate the PTE if necessary; takes PMD lock once only. */
1943 ret = -ENOMEM;
1944 if (pte_alloc(mm, pmd))
1945 goto out;
1946
1947 while (pages_to_write_in_pmd) {
1948 int pte_idx = 0;
1949 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
1950
1951 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
1952 if (!start_pte) {
1953 ret = -EFAULT;
1954 goto out;
1955 }
1956 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
1957 int err = insert_page_in_batch_locked(vma, pte,
1958 addr, pages[curr_page_idx], prot);
1959 if (unlikely(err)) {
1960 pte_unmap_unlock(start_pte, pte_lock);
1961 ret = err;
1962 remaining_pages_total -= pte_idx;
1963 goto out;
1964 }
1965 addr += PAGE_SIZE;
1966 ++curr_page_idx;
1967 }
1968 pte_unmap_unlock(start_pte, pte_lock);
1969 pages_to_write_in_pmd -= batch_size;
1970 remaining_pages_total -= batch_size;
1971 }
1972 if (remaining_pages_total)
1973 goto more;
1974 ret = 0;
1975out:
1976 *num = remaining_pages_total;
1977 return ret;
1978}
1979
1980/**
1981 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1982 * @vma: user vma to map to
1983 * @addr: target start user address of these pages
1984 * @pages: source kernel pages
1985 * @num: in: number of pages to map. out: number of pages that were *not*
1986 * mapped. (0 means all pages were successfully mapped).
1987 *
1988 * Preferred over vm_insert_page() when inserting multiple pages.
1989 *
1990 * In case of error, we may have mapped a subset of the provided
1991 * pages. It is the caller's responsibility to account for this case.
1992 *
1993 * The same restrictions apply as in vm_insert_page().
1994 */
1995int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
1996 struct page **pages, unsigned long *num)
1997{
1998 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
1999
2000 if (addr < vma->vm_start || end_addr >= vma->vm_end)
2001 return -EFAULT;
2002 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2003 BUG_ON(mmap_read_trylock(vma->vm_mm));
2004 BUG_ON(vma->vm_flags & VM_PFNMAP);
2005 vm_flags_set(vma, VM_MIXEDMAP);
2006 }
2007 /* Defer page refcount checking till we're about to map that page. */
2008 return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
2009}
2010EXPORT_SYMBOL(vm_insert_pages);
2011
2012/**
2013 * vm_insert_page - insert single page into user vma
2014 * @vma: user vma to map to
2015 * @addr: target user address of this page
2016 * @page: source kernel page
2017 *
2018 * This allows drivers to insert individual pages they've allocated
2019 * into a user vma.
2020 *
2021 * The page has to be a nice clean _individual_ kernel allocation.
2022 * If you allocate a compound page, you need to have marked it as
2023 * such (__GFP_COMP), or manually just split the page up yourself
2024 * (see split_page()).
2025 *
2026 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2027 * took an arbitrary page protection parameter. This doesn't allow
2028 * that. Your vma protection will have to be set up correctly, which
2029 * means that if you want a shared writable mapping, you'd better
2030 * ask for a shared writable mapping!
2031 *
2032 * The page does not need to be reserved.
2033 *
2034 * Usually this function is called from f_op->mmap() handler
2035 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
2036 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2037 * function from other places, for example from page-fault handler.
2038 *
2039 * Return: %0 on success, negative error code otherwise.
2040 */
2041int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2042 struct page *page)
2043{
2044 if (addr < vma->vm_start || addr >= vma->vm_end)
2045 return -EFAULT;
2046 if (!page_count(page))
2047 return -EINVAL;
2048 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2049 BUG_ON(mmap_read_trylock(vma->vm_mm));
2050 BUG_ON(vma->vm_flags & VM_PFNMAP);
2051 vm_flags_set(vma, VM_MIXEDMAP);
2052 }
2053 return insert_page(vma, addr, page, vma->vm_page_prot);
2054}
2055EXPORT_SYMBOL(vm_insert_page);
2056
2057/*
2058 * __vm_map_pages - maps range of kernel pages into user vma
2059 * @vma: user vma to map to
2060 * @pages: pointer to array of source kernel pages
2061 * @num: number of pages in page array
2062 * @offset: user's requested vm_pgoff
2063 *
2064 * This allows drivers to map range of kernel pages into a user vma.
2065 *
2066 * Return: 0 on success and error code otherwise.
2067 */
2068static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2069 unsigned long num, unsigned long offset)
2070{
2071 unsigned long count = vma_pages(vma);
2072 unsigned long uaddr = vma->vm_start;
2073 int ret, i;
2074
2075 /* Fail if the user requested offset is beyond the end of the object */
2076 if (offset >= num)
2077 return -ENXIO;
2078
2079 /* Fail if the user requested size exceeds available object size */
2080 if (count > num - offset)
2081 return -ENXIO;
2082
2083 for (i = 0; i < count; i++) {
2084 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
2085 if (ret < 0)
2086 return ret;
2087 uaddr += PAGE_SIZE;
2088 }
2089
2090 return 0;
2091}
2092
2093/**
2094 * vm_map_pages - maps range of kernel pages starts with non zero offset
2095 * @vma: user vma to map to
2096 * @pages: pointer to array of source kernel pages
2097 * @num: number of pages in page array
2098 *
2099 * Maps an object consisting of @num pages, catering for the user's
2100 * requested vm_pgoff
2101 *
2102 * If we fail to insert any page into the vma, the function will return
2103 * immediately leaving any previously inserted pages present. Callers
2104 * from the mmap handler may immediately return the error as their caller
2105 * will destroy the vma, removing any successfully inserted pages. Other
2106 * callers should make their own arrangements for calling unmap_region().
2107 *
2108 * Context: Process context. Called by mmap handlers.
2109 * Return: 0 on success and error code otherwise.
2110 */
2111int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2112 unsigned long num)
2113{
2114 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2115}
2116EXPORT_SYMBOL(vm_map_pages);
2117
2118/**
2119 * vm_map_pages_zero - map range of kernel pages starts with zero offset
2120 * @vma: user vma to map to
2121 * @pages: pointer to array of source kernel pages
2122 * @num: number of pages in page array
2123 *
2124 * Similar to vm_map_pages(), except that it explicitly sets the offset
2125 * to 0. This function is intended for the drivers that did not consider
2126 * vm_pgoff.
2127 *
2128 * Context: Process context. Called by mmap handlers.
2129 * Return: 0 on success and error code otherwise.
2130 */
2131int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2132 unsigned long num)
2133{
2134 return __vm_map_pages(vma, pages, num, 0);
2135}
2136EXPORT_SYMBOL(vm_map_pages_zero);
2137
2138static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2139 pfn_t pfn, pgprot_t prot, bool mkwrite)
2140{
2141 struct mm_struct *mm = vma->vm_mm;
2142 pte_t *pte, entry;
2143 spinlock_t *ptl;
2144
2145 pte = get_locked_pte(mm, addr, &ptl);
2146 if (!pte)
2147 return VM_FAULT_OOM;
2148 entry = ptep_get(pte);
2149 if (!pte_none(entry)) {
2150 if (mkwrite) {
2151 /*
2152 * For read faults on private mappings the PFN passed
2153 * in may not match the PFN we have mapped if the
2154 * mapped PFN is a writeable COW page. In the mkwrite
2155 * case we are creating a writable PTE for a shared
2156 * mapping and we expect the PFNs to match. If they
2157 * don't match, we are likely racing with block
2158 * allocation and mapping invalidation so just skip the
2159 * update.
2160 */
2161 if (pte_pfn(entry) != pfn_t_to_pfn(pfn)) {
2162 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry)));
2163 goto out_unlock;
2164 }
2165 entry = pte_mkyoung(entry);
2166 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2167 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2168 update_mmu_cache(vma, addr, pte);
2169 }
2170 goto out_unlock;
2171 }
2172
2173 /* Ok, finally just insert the thing.. */
2174 if (pfn_t_devmap(pfn))
2175 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2176 else
2177 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2178
2179 if (mkwrite) {
2180 entry = pte_mkyoung(entry);
2181 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2182 }
2183
2184 set_pte_at(mm, addr, pte, entry);
2185 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2186
2187out_unlock:
2188 pte_unmap_unlock(pte, ptl);
2189 return VM_FAULT_NOPAGE;
2190}
2191
2192/**
2193 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2194 * @vma: user vma to map to
2195 * @addr: target user address of this page
2196 * @pfn: source kernel pfn
2197 * @pgprot: pgprot flags for the inserted page
2198 *
2199 * This is exactly like vmf_insert_pfn(), except that it allows drivers
2200 * to override pgprot on a per-page basis.
2201 *
2202 * This only makes sense for IO mappings, and it makes no sense for
2203 * COW mappings. In general, using multiple vmas is preferable;
2204 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2205 * impractical.
2206 *
2207 * pgprot typically only differs from @vma->vm_page_prot when drivers set
2208 * caching- and encryption bits different than those of @vma->vm_page_prot,
2209 * because the caching- or encryption mode may not be known at mmap() time.
2210 *
2211 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2212 * to set caching and encryption bits for those vmas (except for COW pages).
2213 * This is ensured by core vm only modifying these page table entries using
2214 * functions that don't touch caching- or encryption bits, using pte_modify()
2215 * if needed. (See for example mprotect()).
2216 *
2217 * Also when new page-table entries are created, this is only done using the
2218 * fault() callback, and never using the value of vma->vm_page_prot,
2219 * except for page-table entries that point to anonymous pages as the result
2220 * of COW.
2221 *
2222 * Context: Process context. May allocate using %GFP_KERNEL.
2223 * Return: vm_fault_t value.
2224 */
2225vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2226 unsigned long pfn, pgprot_t pgprot)
2227{
2228 /*
2229 * Technically, architectures with pte_special can avoid all these
2230 * restrictions (same for remap_pfn_range). However we would like
2231 * consistency in testing and feature parity among all, so we should
2232 * try to keep these invariants in place for everybody.
2233 */
2234 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2235 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2236 (VM_PFNMAP|VM_MIXEDMAP));
2237 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2238 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2239
2240 if (addr < vma->vm_start || addr >= vma->vm_end)
2241 return VM_FAULT_SIGBUS;
2242
2243 if (!pfn_modify_allowed(pfn, pgprot))
2244 return VM_FAULT_SIGBUS;
2245
2246 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2247
2248 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2249 false);
2250}
2251EXPORT_SYMBOL(vmf_insert_pfn_prot);
2252
2253/**
2254 * vmf_insert_pfn - insert single pfn into user vma
2255 * @vma: user vma to map to
2256 * @addr: target user address of this page
2257 * @pfn: source kernel pfn
2258 *
2259 * Similar to vm_insert_page, this allows drivers to insert individual pages
2260 * they've allocated into a user vma. Same comments apply.
2261 *
2262 * This function should only be called from a vm_ops->fault handler, and
2263 * in that case the handler should return the result of this function.
2264 *
2265 * vma cannot be a COW mapping.
2266 *
2267 * As this is called only for pages that do not currently exist, we
2268 * do not need to flush old virtual caches or the TLB.
2269 *
2270 * Context: Process context. May allocate using %GFP_KERNEL.
2271 * Return: vm_fault_t value.
2272 */
2273vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2274 unsigned long pfn)
2275{
2276 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2277}
2278EXPORT_SYMBOL(vmf_insert_pfn);
2279
2280static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
2281{
2282 /* these checks mirror the abort conditions in vm_normal_page */
2283 if (vma->vm_flags & VM_MIXEDMAP)
2284 return true;
2285 if (pfn_t_devmap(pfn))
2286 return true;
2287 if (pfn_t_special(pfn))
2288 return true;
2289 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2290 return true;
2291 return false;
2292}
2293
2294static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2295 unsigned long addr, pfn_t pfn, bool mkwrite)
2296{
2297 pgprot_t pgprot = vma->vm_page_prot;
2298 int err;
2299
2300 BUG_ON(!vm_mixed_ok(vma, pfn));
2301
2302 if (addr < vma->vm_start || addr >= vma->vm_end)
2303 return VM_FAULT_SIGBUS;
2304
2305 track_pfn_insert(vma, &pgprot, pfn);
2306
2307 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2308 return VM_FAULT_SIGBUS;
2309
2310 /*
2311 * If we don't have pte special, then we have to use the pfn_valid()
2312 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2313 * refcount the page if pfn_valid is true (hence insert_page rather
2314 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2315 * without pte special, it would there be refcounted as a normal page.
2316 */
2317 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2318 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2319 struct page *page;
2320
2321 /*
2322 * At this point we are committed to insert_page()
2323 * regardless of whether the caller specified flags that
2324 * result in pfn_t_has_page() == false.
2325 */
2326 page = pfn_to_page(pfn_t_to_pfn(pfn));
2327 err = insert_page(vma, addr, page, pgprot);
2328 } else {
2329 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2330 }
2331
2332 if (err == -ENOMEM)
2333 return VM_FAULT_OOM;
2334 if (err < 0 && err != -EBUSY)
2335 return VM_FAULT_SIGBUS;
2336
2337 return VM_FAULT_NOPAGE;
2338}
2339
2340vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2341 pfn_t pfn)
2342{
2343 return __vm_insert_mixed(vma, addr, pfn, false);
2344}
2345EXPORT_SYMBOL(vmf_insert_mixed);
2346
2347/*
2348 * If the insertion of PTE failed because someone else already added a
2349 * different entry in the mean time, we treat that as success as we assume
2350 * the same entry was actually inserted.
2351 */
2352vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2353 unsigned long addr, pfn_t pfn)
2354{
2355 return __vm_insert_mixed(vma, addr, pfn, true);
2356}
2357EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2358
2359/*
2360 * maps a range of physical memory into the requested pages. the old
2361 * mappings are removed. any references to nonexistent pages results
2362 * in null mappings (currently treated as "copy-on-access")
2363 */
2364static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2365 unsigned long addr, unsigned long end,
2366 unsigned long pfn, pgprot_t prot)
2367{
2368 pte_t *pte, *mapped_pte;
2369 spinlock_t *ptl;
2370 int err = 0;
2371
2372 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2373 if (!pte)
2374 return -ENOMEM;
2375 arch_enter_lazy_mmu_mode();
2376 do {
2377 BUG_ON(!pte_none(ptep_get(pte)));
2378 if (!pfn_modify_allowed(pfn, prot)) {
2379 err = -EACCES;
2380 break;
2381 }
2382 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2383 pfn++;
2384 } while (pte++, addr += PAGE_SIZE, addr != end);
2385 arch_leave_lazy_mmu_mode();
2386 pte_unmap_unlock(mapped_pte, ptl);
2387 return err;
2388}
2389
2390static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2391 unsigned long addr, unsigned long end,
2392 unsigned long pfn, pgprot_t prot)
2393{
2394 pmd_t *pmd;
2395 unsigned long next;
2396 int err;
2397
2398 pfn -= addr >> PAGE_SHIFT;
2399 pmd = pmd_alloc(mm, pud, addr);
2400 if (!pmd)
2401 return -ENOMEM;
2402 VM_BUG_ON(pmd_trans_huge(*pmd));
2403 do {
2404 next = pmd_addr_end(addr, end);
2405 err = remap_pte_range(mm, pmd, addr, next,
2406 pfn + (addr >> PAGE_SHIFT), prot);
2407 if (err)
2408 return err;
2409 } while (pmd++, addr = next, addr != end);
2410 return 0;
2411}
2412
2413static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2414 unsigned long addr, unsigned long end,
2415 unsigned long pfn, pgprot_t prot)
2416{
2417 pud_t *pud;
2418 unsigned long next;
2419 int err;
2420
2421 pfn -= addr >> PAGE_SHIFT;
2422 pud = pud_alloc(mm, p4d, addr);
2423 if (!pud)
2424 return -ENOMEM;
2425 do {
2426 next = pud_addr_end(addr, end);
2427 err = remap_pmd_range(mm, pud, addr, next,
2428 pfn + (addr >> PAGE_SHIFT), prot);
2429 if (err)
2430 return err;
2431 } while (pud++, addr = next, addr != end);
2432 return 0;
2433}
2434
2435static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2436 unsigned long addr, unsigned long end,
2437 unsigned long pfn, pgprot_t prot)
2438{
2439 p4d_t *p4d;
2440 unsigned long next;
2441 int err;
2442
2443 pfn -= addr >> PAGE_SHIFT;
2444 p4d = p4d_alloc(mm, pgd, addr);
2445 if (!p4d)
2446 return -ENOMEM;
2447 do {
2448 next = p4d_addr_end(addr, end);
2449 err = remap_pud_range(mm, p4d, addr, next,
2450 pfn + (addr >> PAGE_SHIFT), prot);
2451 if (err)
2452 return err;
2453 } while (p4d++, addr = next, addr != end);
2454 return 0;
2455}
2456
2457/*
2458 * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
2459 * must have pre-validated the caching bits of the pgprot_t.
2460 */
2461int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2462 unsigned long pfn, unsigned long size, pgprot_t prot)
2463{
2464 pgd_t *pgd;
2465 unsigned long next;
2466 unsigned long end = addr + PAGE_ALIGN(size);
2467 struct mm_struct *mm = vma->vm_mm;
2468 int err;
2469
2470 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2471 return -EINVAL;
2472
2473 /*
2474 * Physically remapped pages are special. Tell the
2475 * rest of the world about it:
2476 * VM_IO tells people not to look at these pages
2477 * (accesses can have side effects).
2478 * VM_PFNMAP tells the core MM that the base pages are just
2479 * raw PFN mappings, and do not have a "struct page" associated
2480 * with them.
2481 * VM_DONTEXPAND
2482 * Disable vma merging and expanding with mremap().
2483 * VM_DONTDUMP
2484 * Omit vma from core dump, even when VM_IO turned off.
2485 *
2486 * There's a horrible special case to handle copy-on-write
2487 * behaviour that some programs depend on. We mark the "original"
2488 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2489 * See vm_normal_page() for details.
2490 */
2491 if (is_cow_mapping(vma->vm_flags)) {
2492 if (addr != vma->vm_start || end != vma->vm_end)
2493 return -EINVAL;
2494 vma->vm_pgoff = pfn;
2495 }
2496
2497 vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
2498
2499 BUG_ON(addr >= end);
2500 pfn -= addr >> PAGE_SHIFT;
2501 pgd = pgd_offset(mm, addr);
2502 flush_cache_range(vma, addr, end);
2503 do {
2504 next = pgd_addr_end(addr, end);
2505 err = remap_p4d_range(mm, pgd, addr, next,
2506 pfn + (addr >> PAGE_SHIFT), prot);
2507 if (err)
2508 return err;
2509 } while (pgd++, addr = next, addr != end);
2510
2511 return 0;
2512}
2513
2514/**
2515 * remap_pfn_range - remap kernel memory to userspace
2516 * @vma: user vma to map to
2517 * @addr: target page aligned user address to start at
2518 * @pfn: page frame number of kernel physical memory address
2519 * @size: size of mapping area
2520 * @prot: page protection flags for this mapping
2521 *
2522 * Note: this is only safe if the mm semaphore is held when called.
2523 *
2524 * Return: %0 on success, negative error code otherwise.
2525 */
2526int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2527 unsigned long pfn, unsigned long size, pgprot_t prot)
2528{
2529 int err;
2530
2531 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2532 if (err)
2533 return -EINVAL;
2534
2535 err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2536 if (err)
2537 untrack_pfn(vma, pfn, PAGE_ALIGN(size), true);
2538 return err;
2539}
2540EXPORT_SYMBOL(remap_pfn_range);
2541
2542/**
2543 * vm_iomap_memory - remap memory to userspace
2544 * @vma: user vma to map to
2545 * @start: start of the physical memory to be mapped
2546 * @len: size of area
2547 *
2548 * This is a simplified io_remap_pfn_range() for common driver use. The
2549 * driver just needs to give us the physical memory range to be mapped,
2550 * we'll figure out the rest from the vma information.
2551 *
2552 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2553 * whatever write-combining details or similar.
2554 *
2555 * Return: %0 on success, negative error code otherwise.
2556 */
2557int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2558{
2559 unsigned long vm_len, pfn, pages;
2560
2561 /* Check that the physical memory area passed in looks valid */
2562 if (start + len < start)
2563 return -EINVAL;
2564 /*
2565 * You *really* shouldn't map things that aren't page-aligned,
2566 * but we've historically allowed it because IO memory might
2567 * just have smaller alignment.
2568 */
2569 len += start & ~PAGE_MASK;
2570 pfn = start >> PAGE_SHIFT;
2571 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2572 if (pfn + pages < pfn)
2573 return -EINVAL;
2574
2575 /* We start the mapping 'vm_pgoff' pages into the area */
2576 if (vma->vm_pgoff > pages)
2577 return -EINVAL;
2578 pfn += vma->vm_pgoff;
2579 pages -= vma->vm_pgoff;
2580
2581 /* Can we fit all of the mapping? */
2582 vm_len = vma->vm_end - vma->vm_start;
2583 if (vm_len >> PAGE_SHIFT > pages)
2584 return -EINVAL;
2585
2586 /* Ok, let it rip */
2587 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2588}
2589EXPORT_SYMBOL(vm_iomap_memory);
2590
2591static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2592 unsigned long addr, unsigned long end,
2593 pte_fn_t fn, void *data, bool create,
2594 pgtbl_mod_mask *mask)
2595{
2596 pte_t *pte, *mapped_pte;
2597 int err = 0;
2598 spinlock_t *ptl;
2599
2600 if (create) {
2601 mapped_pte = pte = (mm == &init_mm) ?
2602 pte_alloc_kernel_track(pmd, addr, mask) :
2603 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2604 if (!pte)
2605 return -ENOMEM;
2606 } else {
2607 mapped_pte = pte = (mm == &init_mm) ?
2608 pte_offset_kernel(pmd, addr) :
2609 pte_offset_map_lock(mm, pmd, addr, &ptl);
2610 if (!pte)
2611 return -EINVAL;
2612 }
2613
2614 arch_enter_lazy_mmu_mode();
2615
2616 if (fn) {
2617 do {
2618 if (create || !pte_none(ptep_get(pte))) {
2619 err = fn(pte++, addr, data);
2620 if (err)
2621 break;
2622 }
2623 } while (addr += PAGE_SIZE, addr != end);
2624 }
2625 *mask |= PGTBL_PTE_MODIFIED;
2626
2627 arch_leave_lazy_mmu_mode();
2628
2629 if (mm != &init_mm)
2630 pte_unmap_unlock(mapped_pte, ptl);
2631 return err;
2632}
2633
2634static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2635 unsigned long addr, unsigned long end,
2636 pte_fn_t fn, void *data, bool create,
2637 pgtbl_mod_mask *mask)
2638{
2639 pmd_t *pmd;
2640 unsigned long next;
2641 int err = 0;
2642
2643 BUG_ON(pud_huge(*pud));
2644
2645 if (create) {
2646 pmd = pmd_alloc_track(mm, pud, addr, mask);
2647 if (!pmd)
2648 return -ENOMEM;
2649 } else {
2650 pmd = pmd_offset(pud, addr);
2651 }
2652 do {
2653 next = pmd_addr_end(addr, end);
2654 if (pmd_none(*pmd) && !create)
2655 continue;
2656 if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2657 return -EINVAL;
2658 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2659 if (!create)
2660 continue;
2661 pmd_clear_bad(pmd);
2662 }
2663 err = apply_to_pte_range(mm, pmd, addr, next,
2664 fn, data, create, mask);
2665 if (err)
2666 break;
2667 } while (pmd++, addr = next, addr != end);
2668
2669 return err;
2670}
2671
2672static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2673 unsigned long addr, unsigned long end,
2674 pte_fn_t fn, void *data, bool create,
2675 pgtbl_mod_mask *mask)
2676{
2677 pud_t *pud;
2678 unsigned long next;
2679 int err = 0;
2680
2681 if (create) {
2682 pud = pud_alloc_track(mm, p4d, addr, mask);
2683 if (!pud)
2684 return -ENOMEM;
2685 } else {
2686 pud = pud_offset(p4d, addr);
2687 }
2688 do {
2689 next = pud_addr_end(addr, end);
2690 if (pud_none(*pud) && !create)
2691 continue;
2692 if (WARN_ON_ONCE(pud_leaf(*pud)))
2693 return -EINVAL;
2694 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2695 if (!create)
2696 continue;
2697 pud_clear_bad(pud);
2698 }
2699 err = apply_to_pmd_range(mm, pud, addr, next,
2700 fn, data, create, mask);
2701 if (err)
2702 break;
2703 } while (pud++, addr = next, addr != end);
2704
2705 return err;
2706}
2707
2708static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2709 unsigned long addr, unsigned long end,
2710 pte_fn_t fn, void *data, bool create,
2711 pgtbl_mod_mask *mask)
2712{
2713 p4d_t *p4d;
2714 unsigned long next;
2715 int err = 0;
2716
2717 if (create) {
2718 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2719 if (!p4d)
2720 return -ENOMEM;
2721 } else {
2722 p4d = p4d_offset(pgd, addr);
2723 }
2724 do {
2725 next = p4d_addr_end(addr, end);
2726 if (p4d_none(*p4d) && !create)
2727 continue;
2728 if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2729 return -EINVAL;
2730 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2731 if (!create)
2732 continue;
2733 p4d_clear_bad(p4d);
2734 }
2735 err = apply_to_pud_range(mm, p4d, addr, next,
2736 fn, data, create, mask);
2737 if (err)
2738 break;
2739 } while (p4d++, addr = next, addr != end);
2740
2741 return err;
2742}
2743
2744static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2745 unsigned long size, pte_fn_t fn,
2746 void *data, bool create)
2747{
2748 pgd_t *pgd;
2749 unsigned long start = addr, next;
2750 unsigned long end = addr + size;
2751 pgtbl_mod_mask mask = 0;
2752 int err = 0;
2753
2754 if (WARN_ON(addr >= end))
2755 return -EINVAL;
2756
2757 pgd = pgd_offset(mm, addr);
2758 do {
2759 next = pgd_addr_end(addr, end);
2760 if (pgd_none(*pgd) && !create)
2761 continue;
2762 if (WARN_ON_ONCE(pgd_leaf(*pgd)))
2763 return -EINVAL;
2764 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2765 if (!create)
2766 continue;
2767 pgd_clear_bad(pgd);
2768 }
2769 err = apply_to_p4d_range(mm, pgd, addr, next,
2770 fn, data, create, &mask);
2771 if (err)
2772 break;
2773 } while (pgd++, addr = next, addr != end);
2774
2775 if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2776 arch_sync_kernel_mappings(start, start + size);
2777
2778 return err;
2779}
2780
2781/*
2782 * Scan a region of virtual memory, filling in page tables as necessary
2783 * and calling a provided function on each leaf page table.
2784 */
2785int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2786 unsigned long size, pte_fn_t fn, void *data)
2787{
2788 return __apply_to_page_range(mm, addr, size, fn, data, true);
2789}
2790EXPORT_SYMBOL_GPL(apply_to_page_range);
2791
2792/*
2793 * Scan a region of virtual memory, calling a provided function on
2794 * each leaf page table where it exists.
2795 *
2796 * Unlike apply_to_page_range, this does _not_ fill in page tables
2797 * where they are absent.
2798 */
2799int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
2800 unsigned long size, pte_fn_t fn, void *data)
2801{
2802 return __apply_to_page_range(mm, addr, size, fn, data, false);
2803}
2804EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
2805
2806/*
2807 * handle_pte_fault chooses page fault handler according to an entry which was
2808 * read non-atomically. Before making any commitment, on those architectures
2809 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2810 * parts, do_swap_page must check under lock before unmapping the pte and
2811 * proceeding (but do_wp_page is only called after already making such a check;
2812 * and do_anonymous_page can safely check later on).
2813 */
2814static inline int pte_unmap_same(struct vm_fault *vmf)
2815{
2816 int same = 1;
2817#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2818 if (sizeof(pte_t) > sizeof(unsigned long)) {
2819 spin_lock(vmf->ptl);
2820 same = pte_same(ptep_get(vmf->pte), vmf->orig_pte);
2821 spin_unlock(vmf->ptl);
2822 }
2823#endif
2824 pte_unmap(vmf->pte);
2825 vmf->pte = NULL;
2826 return same;
2827}
2828
2829/*
2830 * Return:
2831 * 0: copied succeeded
2832 * -EHWPOISON: copy failed due to hwpoison in source page
2833 * -EAGAIN: copied failed (some other reason)
2834 */
2835static inline int __wp_page_copy_user(struct page *dst, struct page *src,
2836 struct vm_fault *vmf)
2837{
2838 int ret;
2839 void *kaddr;
2840 void __user *uaddr;
2841 struct vm_area_struct *vma = vmf->vma;
2842 struct mm_struct *mm = vma->vm_mm;
2843 unsigned long addr = vmf->address;
2844
2845 if (likely(src)) {
2846 if (copy_mc_user_highpage(dst, src, addr, vma)) {
2847 memory_failure_queue(page_to_pfn(src), 0);
2848 return -EHWPOISON;
2849 }
2850 return 0;
2851 }
2852
2853 /*
2854 * If the source page was a PFN mapping, we don't have
2855 * a "struct page" for it. We do a best-effort copy by
2856 * just copying from the original user address. If that
2857 * fails, we just zero-fill it. Live with it.
2858 */
2859 kaddr = kmap_local_page(dst);
2860 pagefault_disable();
2861 uaddr = (void __user *)(addr & PAGE_MASK);
2862
2863 /*
2864 * On architectures with software "accessed" bits, we would
2865 * take a double page fault, so mark it accessed here.
2866 */
2867 vmf->pte = NULL;
2868 if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
2869 pte_t entry;
2870
2871 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2872 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
2873 /*
2874 * Other thread has already handled the fault
2875 * and update local tlb only
2876 */
2877 if (vmf->pte)
2878 update_mmu_tlb(vma, addr, vmf->pte);
2879 ret = -EAGAIN;
2880 goto pte_unlock;
2881 }
2882
2883 entry = pte_mkyoung(vmf->orig_pte);
2884 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2885 update_mmu_cache_range(vmf, vma, addr, vmf->pte, 1);
2886 }
2887
2888 /*
2889 * This really shouldn't fail, because the page is there
2890 * in the page tables. But it might just be unreadable,
2891 * in which case we just give up and fill the result with
2892 * zeroes.
2893 */
2894 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2895 if (vmf->pte)
2896 goto warn;
2897
2898 /* Re-validate under PTL if the page is still mapped */
2899 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2900 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
2901 /* The PTE changed under us, update local tlb */
2902 if (vmf->pte)
2903 update_mmu_tlb(vma, addr, vmf->pte);
2904 ret = -EAGAIN;
2905 goto pte_unlock;
2906 }
2907
2908 /*
2909 * The same page can be mapped back since last copy attempt.
2910 * Try to copy again under PTL.
2911 */
2912 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2913 /*
2914 * Give a warn in case there can be some obscure
2915 * use-case
2916 */
2917warn:
2918 WARN_ON_ONCE(1);
2919 clear_page(kaddr);
2920 }
2921 }
2922
2923 ret = 0;
2924
2925pte_unlock:
2926 if (vmf->pte)
2927 pte_unmap_unlock(vmf->pte, vmf->ptl);
2928 pagefault_enable();
2929 kunmap_local(kaddr);
2930 flush_dcache_page(dst);
2931
2932 return ret;
2933}
2934
2935static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2936{
2937 struct file *vm_file = vma->vm_file;
2938
2939 if (vm_file)
2940 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2941
2942 /*
2943 * Special mappings (e.g. VDSO) do not have any file so fake
2944 * a default GFP_KERNEL for them.
2945 */
2946 return GFP_KERNEL;
2947}
2948
2949/*
2950 * Notify the address space that the page is about to become writable so that
2951 * it can prohibit this or wait for the page to get into an appropriate state.
2952 *
2953 * We do this without the lock held, so that it can sleep if it needs to.
2954 */
2955static vm_fault_t do_page_mkwrite(struct vm_fault *vmf, struct folio *folio)
2956{
2957 vm_fault_t ret;
2958 unsigned int old_flags = vmf->flags;
2959
2960 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2961
2962 if (vmf->vma->vm_file &&
2963 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2964 return VM_FAULT_SIGBUS;
2965
2966 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2967 /* Restore original flags so that caller is not surprised */
2968 vmf->flags = old_flags;
2969 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2970 return ret;
2971 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2972 folio_lock(folio);
2973 if (!folio->mapping) {
2974 folio_unlock(folio);
2975 return 0; /* retry */
2976 }
2977 ret |= VM_FAULT_LOCKED;
2978 } else
2979 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
2980 return ret;
2981}
2982
2983/*
2984 * Handle dirtying of a page in shared file mapping on a write fault.
2985 *
2986 * The function expects the page to be locked and unlocks it.
2987 */
2988static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
2989{
2990 struct vm_area_struct *vma = vmf->vma;
2991 struct address_space *mapping;
2992 struct folio *folio = page_folio(vmf->page);
2993 bool dirtied;
2994 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2995
2996 dirtied = folio_mark_dirty(folio);
2997 VM_BUG_ON_FOLIO(folio_test_anon(folio), folio);
2998 /*
2999 * Take a local copy of the address_space - folio.mapping may be zeroed
3000 * by truncate after folio_unlock(). The address_space itself remains
3001 * pinned by vma->vm_file's reference. We rely on folio_unlock()'s
3002 * release semantics to prevent the compiler from undoing this copying.
3003 */
3004 mapping = folio_raw_mapping(folio);
3005 folio_unlock(folio);
3006
3007 if (!page_mkwrite)
3008 file_update_time(vma->vm_file);
3009
3010 /*
3011 * Throttle page dirtying rate down to writeback speed.
3012 *
3013 * mapping may be NULL here because some device drivers do not
3014 * set page.mapping but still dirty their pages
3015 *
3016 * Drop the mmap_lock before waiting on IO, if we can. The file
3017 * is pinning the mapping, as per above.
3018 */
3019 if ((dirtied || page_mkwrite) && mapping) {
3020 struct file *fpin;
3021
3022 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
3023 balance_dirty_pages_ratelimited(mapping);
3024 if (fpin) {
3025 fput(fpin);
3026 return VM_FAULT_COMPLETED;
3027 }
3028 }
3029
3030 return 0;
3031}
3032
3033/*
3034 * Handle write page faults for pages that can be reused in the current vma
3035 *
3036 * This can happen either due to the mapping being with the VM_SHARED flag,
3037 * or due to us being the last reference standing to the page. In either
3038 * case, all we need to do here is to mark the page as writable and update
3039 * any related book-keeping.
3040 */
3041static inline void wp_page_reuse(struct vm_fault *vmf, struct folio *folio)
3042 __releases(vmf->ptl)
3043{
3044 struct vm_area_struct *vma = vmf->vma;
3045 pte_t entry;
3046
3047 VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE));
3048
3049 if (folio) {
3050 VM_BUG_ON(folio_test_anon(folio) &&
3051 !PageAnonExclusive(vmf->page));
3052 /*
3053 * Clear the folio's cpupid information as the existing
3054 * information potentially belongs to a now completely
3055 * unrelated process.
3056 */
3057 folio_xchg_last_cpupid(folio, (1 << LAST_CPUPID_SHIFT) - 1);
3058 }
3059
3060 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3061 entry = pte_mkyoung(vmf->orig_pte);
3062 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3063 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
3064 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
3065 pte_unmap_unlock(vmf->pte, vmf->ptl);
3066 count_vm_event(PGREUSE);
3067}
3068
3069/*
3070 * We could add a bitflag somewhere, but for now, we know that all
3071 * vm_ops that have a ->map_pages have been audited and don't need
3072 * the mmap_lock to be held.
3073 */
3074static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf)
3075{
3076 struct vm_area_struct *vma = vmf->vma;
3077
3078 if (vma->vm_ops->map_pages || !(vmf->flags & FAULT_FLAG_VMA_LOCK))
3079 return 0;
3080 vma_end_read(vma);
3081 return VM_FAULT_RETRY;
3082}
3083
3084static vm_fault_t vmf_anon_prepare(struct vm_fault *vmf)
3085{
3086 struct vm_area_struct *vma = vmf->vma;
3087
3088 if (likely(vma->anon_vma))
3089 return 0;
3090 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
3091 vma_end_read(vma);
3092 return VM_FAULT_RETRY;
3093 }
3094 if (__anon_vma_prepare(vma))
3095 return VM_FAULT_OOM;
3096 return 0;
3097}
3098
3099/*
3100 * Handle the case of a page which we actually need to copy to a new page,
3101 * either due to COW or unsharing.
3102 *
3103 * Called with mmap_lock locked and the old page referenced, but
3104 * without the ptl held.
3105 *
3106 * High level logic flow:
3107 *
3108 * - Allocate a page, copy the content of the old page to the new one.
3109 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
3110 * - Take the PTL. If the pte changed, bail out and release the allocated page
3111 * - If the pte is still the way we remember it, update the page table and all
3112 * relevant references. This includes dropping the reference the page-table
3113 * held to the old page, as well as updating the rmap.
3114 * - In any case, unlock the PTL and drop the reference we took to the old page.
3115 */
3116static vm_fault_t wp_page_copy(struct vm_fault *vmf)
3117{
3118 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3119 struct vm_area_struct *vma = vmf->vma;
3120 struct mm_struct *mm = vma->vm_mm;
3121 struct folio *old_folio = NULL;
3122 struct folio *new_folio = NULL;
3123 pte_t entry;
3124 int page_copied = 0;
3125 struct mmu_notifier_range range;
3126 vm_fault_t ret;
3127 bool pfn_is_zero;
3128
3129 delayacct_wpcopy_start();
3130
3131 if (vmf->page)
3132 old_folio = page_folio(vmf->page);
3133 ret = vmf_anon_prepare(vmf);
3134 if (unlikely(ret))
3135 goto out;
3136
3137 pfn_is_zero = is_zero_pfn(pte_pfn(vmf->orig_pte));
3138 new_folio = folio_prealloc(mm, vma, vmf->address, pfn_is_zero);
3139 if (!new_folio)
3140 goto oom;
3141
3142 if (!pfn_is_zero) {
3143 int err;
3144
3145 err = __wp_page_copy_user(&new_folio->page, vmf->page, vmf);
3146 if (err) {
3147 /*
3148 * COW failed, if the fault was solved by other,
3149 * it's fine. If not, userspace would re-fault on
3150 * the same address and we will handle the fault
3151 * from the second attempt.
3152 * The -EHWPOISON case will not be retried.
3153 */
3154 folio_put(new_folio);
3155 if (old_folio)
3156 folio_put(old_folio);
3157
3158 delayacct_wpcopy_end();
3159 return err == -EHWPOISON ? VM_FAULT_HWPOISON : 0;
3160 }
3161 kmsan_copy_page_meta(&new_folio->page, vmf->page);
3162 }
3163
3164 __folio_mark_uptodate(new_folio);
3165
3166 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
3167 vmf->address & PAGE_MASK,
3168 (vmf->address & PAGE_MASK) + PAGE_SIZE);
3169 mmu_notifier_invalidate_range_start(&range);
3170
3171 /*
3172 * Re-check the pte - we dropped the lock
3173 */
3174 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3175 if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3176 if (old_folio) {
3177 if (!folio_test_anon(old_folio)) {
3178 dec_mm_counter(mm, mm_counter_file(&old_folio->page));
3179 inc_mm_counter(mm, MM_ANONPAGES);
3180 }
3181 } else {
3182 ksm_might_unmap_zero_page(mm, vmf->orig_pte);
3183 inc_mm_counter(mm, MM_ANONPAGES);
3184 }
3185 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3186 entry = mk_pte(&new_folio->page, vma->vm_page_prot);
3187 entry = pte_sw_mkyoung(entry);
3188 if (unlikely(unshare)) {
3189 if (pte_soft_dirty(vmf->orig_pte))
3190 entry = pte_mksoft_dirty(entry);
3191 if (pte_uffd_wp(vmf->orig_pte))
3192 entry = pte_mkuffd_wp(entry);
3193 } else {
3194 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3195 }
3196
3197 /*
3198 * Clear the pte entry and flush it first, before updating the
3199 * pte with the new entry, to keep TLBs on different CPUs in
3200 * sync. This code used to set the new PTE then flush TLBs, but
3201 * that left a window where the new PTE could be loaded into
3202 * some TLBs while the old PTE remains in others.
3203 */
3204 ptep_clear_flush(vma, vmf->address, vmf->pte);
3205 folio_add_new_anon_rmap(new_folio, vma, vmf->address);
3206 folio_add_lru_vma(new_folio, vma);
3207 /*
3208 * We call the notify macro here because, when using secondary
3209 * mmu page tables (such as kvm shadow page tables), we want the
3210 * new page to be mapped directly into the secondary page table.
3211 */
3212 BUG_ON(unshare && pte_write(entry));
3213 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
3214 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
3215 if (old_folio) {
3216 /*
3217 * Only after switching the pte to the new page may
3218 * we remove the mapcount here. Otherwise another
3219 * process may come and find the rmap count decremented
3220 * before the pte is switched to the new page, and
3221 * "reuse" the old page writing into it while our pte
3222 * here still points into it and can be read by other
3223 * threads.
3224 *
3225 * The critical issue is to order this
3226 * folio_remove_rmap_pte() with the ptp_clear_flush
3227 * above. Those stores are ordered by (if nothing else,)
3228 * the barrier present in the atomic_add_negative
3229 * in folio_remove_rmap_pte();
3230 *
3231 * Then the TLB flush in ptep_clear_flush ensures that
3232 * no process can access the old page before the
3233 * decremented mapcount is visible. And the old page
3234 * cannot be reused until after the decremented
3235 * mapcount is visible. So transitively, TLBs to
3236 * old page will be flushed before it can be reused.
3237 */
3238 folio_remove_rmap_pte(old_folio, vmf->page, vma);
3239 }
3240
3241 /* Free the old page.. */
3242 new_folio = old_folio;
3243 page_copied = 1;
3244 pte_unmap_unlock(vmf->pte, vmf->ptl);
3245 } else if (vmf->pte) {
3246 update_mmu_tlb(vma, vmf->address, vmf->pte);
3247 pte_unmap_unlock(vmf->pte, vmf->ptl);
3248 }
3249
3250 mmu_notifier_invalidate_range_end(&range);
3251
3252 if (new_folio)
3253 folio_put(new_folio);
3254 if (old_folio) {
3255 if (page_copied)
3256 free_swap_cache(&old_folio->page);
3257 folio_put(old_folio);
3258 }
3259
3260 delayacct_wpcopy_end();
3261 return 0;
3262oom:
3263 ret = VM_FAULT_OOM;
3264out:
3265 if (old_folio)
3266 folio_put(old_folio);
3267
3268 delayacct_wpcopy_end();
3269 return ret;
3270}
3271
3272/**
3273 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3274 * writeable once the page is prepared
3275 *
3276 * @vmf: structure describing the fault
3277 * @folio: the folio of vmf->page
3278 *
3279 * This function handles all that is needed to finish a write page fault in a
3280 * shared mapping due to PTE being read-only once the mapped page is prepared.
3281 * It handles locking of PTE and modifying it.
3282 *
3283 * The function expects the page to be locked or other protection against
3284 * concurrent faults / writeback (such as DAX radix tree locks).
3285 *
3286 * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3287 * we acquired PTE lock.
3288 */
3289static vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf, struct folio *folio)
3290{
3291 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3292 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3293 &vmf->ptl);
3294 if (!vmf->pte)
3295 return VM_FAULT_NOPAGE;
3296 /*
3297 * We might have raced with another page fault while we released the
3298 * pte_offset_map_lock.
3299 */
3300 if (!pte_same(ptep_get(vmf->pte), vmf->orig_pte)) {
3301 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3302 pte_unmap_unlock(vmf->pte, vmf->ptl);
3303 return VM_FAULT_NOPAGE;
3304 }
3305 wp_page_reuse(vmf, folio);
3306 return 0;
3307}
3308
3309/*
3310 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3311 * mapping
3312 */
3313static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3314{
3315 struct vm_area_struct *vma = vmf->vma;
3316
3317 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3318 vm_fault_t ret;
3319
3320 pte_unmap_unlock(vmf->pte, vmf->ptl);
3321 ret = vmf_can_call_fault(vmf);
3322 if (ret)
3323 return ret;
3324
3325 vmf->flags |= FAULT_FLAG_MKWRITE;
3326 ret = vma->vm_ops->pfn_mkwrite(vmf);
3327 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3328 return ret;
3329 return finish_mkwrite_fault(vmf, NULL);
3330 }
3331 wp_page_reuse(vmf, NULL);
3332 return 0;
3333}
3334
3335static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio)
3336 __releases(vmf->ptl)
3337{
3338 struct vm_area_struct *vma = vmf->vma;
3339 vm_fault_t ret = 0;
3340
3341 folio_get(folio);
3342
3343 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3344 vm_fault_t tmp;
3345
3346 pte_unmap_unlock(vmf->pte, vmf->ptl);
3347 tmp = vmf_can_call_fault(vmf);
3348 if (tmp) {
3349 folio_put(folio);
3350 return tmp;
3351 }
3352
3353 tmp = do_page_mkwrite(vmf, folio);
3354 if (unlikely(!tmp || (tmp &
3355 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3356 folio_put(folio);
3357 return tmp;
3358 }
3359 tmp = finish_mkwrite_fault(vmf, folio);
3360 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3361 folio_unlock(folio);
3362 folio_put(folio);
3363 return tmp;
3364 }
3365 } else {
3366 wp_page_reuse(vmf, folio);
3367 folio_lock(folio);
3368 }
3369 ret |= fault_dirty_shared_page(vmf);
3370 folio_put(folio);
3371
3372 return ret;
3373}
3374
3375static bool wp_can_reuse_anon_folio(struct folio *folio,
3376 struct vm_area_struct *vma)
3377{
3378 /*
3379 * We have to verify under folio lock: these early checks are
3380 * just an optimization to avoid locking the folio and freeing
3381 * the swapcache if there is little hope that we can reuse.
3382 *
3383 * KSM doesn't necessarily raise the folio refcount.
3384 */
3385 if (folio_test_ksm(folio) || folio_ref_count(folio) > 3)
3386 return false;
3387 if (!folio_test_lru(folio))
3388 /*
3389 * We cannot easily detect+handle references from
3390 * remote LRU caches or references to LRU folios.
3391 */
3392 lru_add_drain();
3393 if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio))
3394 return false;
3395 if (!folio_trylock(folio))
3396 return false;
3397 if (folio_test_swapcache(folio))
3398 folio_free_swap(folio);
3399 if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) {
3400 folio_unlock(folio);
3401 return false;
3402 }
3403 /*
3404 * Ok, we've got the only folio reference from our mapping
3405 * and the folio is locked, it's dark out, and we're wearing
3406 * sunglasses. Hit it.
3407 */
3408 folio_move_anon_rmap(folio, vma);
3409 folio_unlock(folio);
3410 return true;
3411}
3412
3413/*
3414 * This routine handles present pages, when
3415 * * users try to write to a shared page (FAULT_FLAG_WRITE)
3416 * * GUP wants to take a R/O pin on a possibly shared anonymous page
3417 * (FAULT_FLAG_UNSHARE)
3418 *
3419 * It is done by copying the page to a new address and decrementing the
3420 * shared-page counter for the old page.
3421 *
3422 * Note that this routine assumes that the protection checks have been
3423 * done by the caller (the low-level page fault routine in most cases).
3424 * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've
3425 * done any necessary COW.
3426 *
3427 * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even
3428 * though the page will change only once the write actually happens. This
3429 * avoids a few races, and potentially makes it more efficient.
3430 *
3431 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3432 * but allow concurrent faults), with pte both mapped and locked.
3433 * We return with mmap_lock still held, but pte unmapped and unlocked.
3434 */
3435static vm_fault_t do_wp_page(struct vm_fault *vmf)
3436 __releases(vmf->ptl)
3437{
3438 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3439 struct vm_area_struct *vma = vmf->vma;
3440 struct folio *folio = NULL;
3441 pte_t pte;
3442
3443 if (likely(!unshare)) {
3444 if (userfaultfd_pte_wp(vma, ptep_get(vmf->pte))) {
3445 if (!userfaultfd_wp_async(vma)) {
3446 pte_unmap_unlock(vmf->pte, vmf->ptl);
3447 return handle_userfault(vmf, VM_UFFD_WP);
3448 }
3449
3450 /*
3451 * Nothing needed (cache flush, TLB invalidations,
3452 * etc.) because we're only removing the uffd-wp bit,
3453 * which is completely invisible to the user.
3454 */
3455 pte = pte_clear_uffd_wp(ptep_get(vmf->pte));
3456
3457 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3458 /*
3459 * Update this to be prepared for following up CoW
3460 * handling
3461 */
3462 vmf->orig_pte = pte;
3463 }
3464
3465 /*
3466 * Userfaultfd write-protect can defer flushes. Ensure the TLB
3467 * is flushed in this case before copying.
3468 */
3469 if (unlikely(userfaultfd_wp(vmf->vma) &&
3470 mm_tlb_flush_pending(vmf->vma->vm_mm)))
3471 flush_tlb_page(vmf->vma, vmf->address);
3472 }
3473
3474 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3475
3476 if (vmf->page)
3477 folio = page_folio(vmf->page);
3478
3479 /*
3480 * Shared mapping: we are guaranteed to have VM_WRITE and
3481 * FAULT_FLAG_WRITE set at this point.
3482 */
3483 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
3484 /*
3485 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3486 * VM_PFNMAP VMA.
3487 *
3488 * We should not cow pages in a shared writeable mapping.
3489 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3490 */
3491 if (!vmf->page)
3492 return wp_pfn_shared(vmf);
3493 return wp_page_shared(vmf, folio);
3494 }
3495
3496 /*
3497 * Private mapping: create an exclusive anonymous page copy if reuse
3498 * is impossible. We might miss VM_WRITE for FOLL_FORCE handling.
3499 *
3500 * If we encounter a page that is marked exclusive, we must reuse
3501 * the page without further checks.
3502 */
3503 if (folio && folio_test_anon(folio) &&
3504 (PageAnonExclusive(vmf->page) || wp_can_reuse_anon_folio(folio, vma))) {
3505 if (!PageAnonExclusive(vmf->page))
3506 SetPageAnonExclusive(vmf->page);
3507 if (unlikely(unshare)) {
3508 pte_unmap_unlock(vmf->pte, vmf->ptl);
3509 return 0;
3510 }
3511 wp_page_reuse(vmf, folio);
3512 return 0;
3513 }
3514 /*
3515 * Ok, we need to copy. Oh, well..
3516 */
3517 if (folio)
3518 folio_get(folio);
3519
3520 pte_unmap_unlock(vmf->pte, vmf->ptl);
3521#ifdef CONFIG_KSM
3522 if (folio && folio_test_ksm(folio))
3523 count_vm_event(COW_KSM);
3524#endif
3525 return wp_page_copy(vmf);
3526}
3527
3528static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3529 unsigned long start_addr, unsigned long end_addr,
3530 struct zap_details *details)
3531{
3532 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3533}
3534
3535static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3536 pgoff_t first_index,
3537 pgoff_t last_index,
3538 struct zap_details *details)
3539{
3540 struct vm_area_struct *vma;
3541 pgoff_t vba, vea, zba, zea;
3542
3543 vma_interval_tree_foreach(vma, root, first_index, last_index) {
3544 vba = vma->vm_pgoff;
3545 vea = vba + vma_pages(vma) - 1;
3546 zba = max(first_index, vba);
3547 zea = min(last_index, vea);
3548
3549 unmap_mapping_range_vma(vma,
3550 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3551 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3552 details);
3553 }
3554}
3555
3556/**
3557 * unmap_mapping_folio() - Unmap single folio from processes.
3558 * @folio: The locked folio to be unmapped.
3559 *
3560 * Unmap this folio from any userspace process which still has it mmaped.
3561 * Typically, for efficiency, the range of nearby pages has already been
3562 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
3563 * truncation or invalidation holds the lock on a folio, it may find that
3564 * the page has been remapped again: and then uses unmap_mapping_folio()
3565 * to unmap it finally.
3566 */
3567void unmap_mapping_folio(struct folio *folio)
3568{
3569 struct address_space *mapping = folio->mapping;
3570 struct zap_details details = { };
3571 pgoff_t first_index;
3572 pgoff_t last_index;
3573
3574 VM_BUG_ON(!folio_test_locked(folio));
3575
3576 first_index = folio->index;
3577 last_index = folio_next_index(folio) - 1;
3578
3579 details.even_cows = false;
3580 details.single_folio = folio;
3581 details.zap_flags = ZAP_FLAG_DROP_MARKER;
3582
3583 i_mmap_lock_read(mapping);
3584 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3585 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3586 last_index, &details);
3587 i_mmap_unlock_read(mapping);
3588}
3589
3590/**
3591 * unmap_mapping_pages() - Unmap pages from processes.
3592 * @mapping: The address space containing pages to be unmapped.
3593 * @start: Index of first page to be unmapped.
3594 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3595 * @even_cows: Whether to unmap even private COWed pages.
3596 *
3597 * Unmap the pages in this address space from any userspace process which
3598 * has them mmaped. Generally, you want to remove COWed pages as well when
3599 * a file is being truncated, but not when invalidating pages from the page
3600 * cache.
3601 */
3602void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3603 pgoff_t nr, bool even_cows)
3604{
3605 struct zap_details details = { };
3606 pgoff_t first_index = start;
3607 pgoff_t last_index = start + nr - 1;
3608
3609 details.even_cows = even_cows;
3610 if (last_index < first_index)
3611 last_index = ULONG_MAX;
3612
3613 i_mmap_lock_read(mapping);
3614 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3615 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3616 last_index, &details);
3617 i_mmap_unlock_read(mapping);
3618}
3619EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3620
3621/**
3622 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3623 * address_space corresponding to the specified byte range in the underlying
3624 * file.
3625 *
3626 * @mapping: the address space containing mmaps to be unmapped.
3627 * @holebegin: byte in first page to unmap, relative to the start of
3628 * the underlying file. This will be rounded down to a PAGE_SIZE
3629 * boundary. Note that this is different from truncate_pagecache(), which
3630 * must keep the partial page. In contrast, we must get rid of
3631 * partial pages.
3632 * @holelen: size of prospective hole in bytes. This will be rounded
3633 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3634 * end of the file.
3635 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3636 * but 0 when invalidating pagecache, don't throw away private data.
3637 */
3638void unmap_mapping_range(struct address_space *mapping,
3639 loff_t const holebegin, loff_t const holelen, int even_cows)
3640{
3641 pgoff_t hba = (pgoff_t)(holebegin) >> PAGE_SHIFT;
3642 pgoff_t hlen = ((pgoff_t)(holelen) + PAGE_SIZE - 1) >> PAGE_SHIFT;
3643
3644 /* Check for overflow. */
3645 if (sizeof(holelen) > sizeof(hlen)) {
3646 long long holeend =
3647 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3648 if (holeend & ~(long long)ULONG_MAX)
3649 hlen = ULONG_MAX - hba + 1;
3650 }
3651
3652 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3653}
3654EXPORT_SYMBOL(unmap_mapping_range);
3655
3656/*
3657 * Restore a potential device exclusive pte to a working pte entry
3658 */
3659static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3660{
3661 struct folio *folio = page_folio(vmf->page);
3662 struct vm_area_struct *vma = vmf->vma;
3663 struct mmu_notifier_range range;
3664 vm_fault_t ret;
3665
3666 /*
3667 * We need a reference to lock the folio because we don't hold
3668 * the PTL so a racing thread can remove the device-exclusive
3669 * entry and unmap it. If the folio is free the entry must
3670 * have been removed already. If it happens to have already
3671 * been re-allocated after being freed all we do is lock and
3672 * unlock it.
3673 */
3674 if (!folio_try_get(folio))
3675 return 0;
3676
3677 ret = folio_lock_or_retry(folio, vmf);
3678 if (ret) {
3679 folio_put(folio);
3680 return ret;
3681 }
3682 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0,
3683 vma->vm_mm, vmf->address & PAGE_MASK,
3684 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3685 mmu_notifier_invalidate_range_start(&range);
3686
3687 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3688 &vmf->ptl);
3689 if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
3690 restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
3691
3692 if (vmf->pte)
3693 pte_unmap_unlock(vmf->pte, vmf->ptl);
3694 folio_unlock(folio);
3695 folio_put(folio);
3696
3697 mmu_notifier_invalidate_range_end(&range);
3698 return 0;
3699}
3700
3701static inline bool should_try_to_free_swap(struct folio *folio,
3702 struct vm_area_struct *vma,
3703 unsigned int fault_flags)
3704{
3705 if (!folio_test_swapcache(folio))
3706 return false;
3707 if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
3708 folio_test_mlocked(folio))
3709 return true;
3710 /*
3711 * If we want to map a page that's in the swapcache writable, we
3712 * have to detect via the refcount if we're really the exclusive
3713 * user. Try freeing the swapcache to get rid of the swapcache
3714 * reference only in case it's likely that we'll be the exlusive user.
3715 */
3716 return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
3717 folio_ref_count(folio) == 2;
3718}
3719
3720static vm_fault_t pte_marker_clear(struct vm_fault *vmf)
3721{
3722 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
3723 vmf->address, &vmf->ptl);
3724 if (!vmf->pte)
3725 return 0;
3726 /*
3727 * Be careful so that we will only recover a special uffd-wp pte into a
3728 * none pte. Otherwise it means the pte could have changed, so retry.
3729 *
3730 * This should also cover the case where e.g. the pte changed
3731 * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_POISONED.
3732 * So is_pte_marker() check is not enough to safely drop the pte.
3733 */
3734 if (pte_same(vmf->orig_pte, ptep_get(vmf->pte)))
3735 pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte);
3736 pte_unmap_unlock(vmf->pte, vmf->ptl);
3737 return 0;
3738}
3739
3740static vm_fault_t do_pte_missing(struct vm_fault *vmf)
3741{
3742 if (vma_is_anonymous(vmf->vma))
3743 return do_anonymous_page(vmf);
3744 else
3745 return do_fault(vmf);
3746}
3747
3748/*
3749 * This is actually a page-missing access, but with uffd-wp special pte
3750 * installed. It means this pte was wr-protected before being unmapped.
3751 */
3752static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf)
3753{
3754 /*
3755 * Just in case there're leftover special ptes even after the region
3756 * got unregistered - we can simply clear them.
3757 */
3758 if (unlikely(!userfaultfd_wp(vmf->vma)))
3759 return pte_marker_clear(vmf);
3760
3761 return do_pte_missing(vmf);
3762}
3763
3764static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
3765{
3766 swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte);
3767 unsigned long marker = pte_marker_get(entry);
3768
3769 /*
3770 * PTE markers should never be empty. If anything weird happened,
3771 * the best thing to do is to kill the process along with its mm.
3772 */
3773 if (WARN_ON_ONCE(!marker))
3774 return VM_FAULT_SIGBUS;
3775
3776 /* Higher priority than uffd-wp when data corrupted */
3777 if (marker & PTE_MARKER_POISONED)
3778 return VM_FAULT_HWPOISON;
3779
3780 if (pte_marker_entry_uffd_wp(entry))
3781 return pte_marker_handle_uffd_wp(vmf);
3782
3783 /* This is an unknown pte marker */
3784 return VM_FAULT_SIGBUS;
3785}
3786
3787/*
3788 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3789 * but allow concurrent faults), and pte mapped but not yet locked.
3790 * We return with pte unmapped and unlocked.
3791 *
3792 * We return with the mmap_lock locked or unlocked in the same cases
3793 * as does filemap_fault().
3794 */
3795vm_fault_t do_swap_page(struct vm_fault *vmf)
3796{
3797 struct vm_area_struct *vma = vmf->vma;
3798 struct folio *swapcache, *folio = NULL;
3799 struct page *page;
3800 struct swap_info_struct *si = NULL;
3801 rmap_t rmap_flags = RMAP_NONE;
3802 bool need_clear_cache = false;
3803 bool exclusive = false;
3804 swp_entry_t entry;
3805 pte_t pte;
3806 vm_fault_t ret = 0;
3807 void *shadow = NULL;
3808
3809 if (!pte_unmap_same(vmf))
3810 goto out;
3811
3812 entry = pte_to_swp_entry(vmf->orig_pte);
3813 if (unlikely(non_swap_entry(entry))) {
3814 if (is_migration_entry(entry)) {
3815 migration_entry_wait(vma->vm_mm, vmf->pmd,
3816 vmf->address);
3817 } else if (is_device_exclusive_entry(entry)) {
3818 vmf->page = pfn_swap_entry_to_page(entry);
3819 ret = remove_device_exclusive_entry(vmf);
3820 } else if (is_device_private_entry(entry)) {
3821 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
3822 /*
3823 * migrate_to_ram is not yet ready to operate
3824 * under VMA lock.
3825 */
3826 vma_end_read(vma);
3827 ret = VM_FAULT_RETRY;
3828 goto out;
3829 }
3830
3831 vmf->page = pfn_swap_entry_to_page(entry);
3832 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3833 vmf->address, &vmf->ptl);
3834 if (unlikely(!vmf->pte ||
3835 !pte_same(ptep_get(vmf->pte),
3836 vmf->orig_pte)))
3837 goto unlock;
3838
3839 /*
3840 * Get a page reference while we know the page can't be
3841 * freed.
3842 */
3843 get_page(vmf->page);
3844 pte_unmap_unlock(vmf->pte, vmf->ptl);
3845 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
3846 put_page(vmf->page);
3847 } else if (is_hwpoison_entry(entry)) {
3848 ret = VM_FAULT_HWPOISON;
3849 } else if (is_pte_marker_entry(entry)) {
3850 ret = handle_pte_marker(vmf);
3851 } else {
3852 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3853 ret = VM_FAULT_SIGBUS;
3854 }
3855 goto out;
3856 }
3857
3858 /* Prevent swapoff from happening to us. */
3859 si = get_swap_device(entry);
3860 if (unlikely(!si))
3861 goto out;
3862
3863 folio = swap_cache_get_folio(entry, vma, vmf->address);
3864 if (folio)
3865 page = folio_file_page(folio, swp_offset(entry));
3866 swapcache = folio;
3867
3868 if (!folio) {
3869 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
3870 __swap_count(entry) == 1) {
3871 /*
3872 * Prevent parallel swapin from proceeding with
3873 * the cache flag. Otherwise, another thread may
3874 * finish swapin first, free the entry, and swapout
3875 * reusing the same entry. It's undetectable as
3876 * pte_same() returns true due to entry reuse.
3877 */
3878 if (swapcache_prepare(entry)) {
3879 /* Relax a bit to prevent rapid repeated page faults */
3880 schedule_timeout_uninterruptible(1);
3881 goto out;
3882 }
3883 need_clear_cache = true;
3884
3885 /* skip swapcache */
3886 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
3887 vma, vmf->address, false);
3888 page = &folio->page;
3889 if (folio) {
3890 __folio_set_locked(folio);
3891 __folio_set_swapbacked(folio);
3892
3893 if (mem_cgroup_swapin_charge_folio(folio,
3894 vma->vm_mm, GFP_KERNEL,
3895 entry)) {
3896 ret = VM_FAULT_OOM;
3897 goto out_page;
3898 }
3899 mem_cgroup_swapin_uncharge_swap(entry);
3900
3901 shadow = get_shadow_from_swap_cache(entry);
3902 if (shadow)
3903 workingset_refault(folio, shadow);
3904
3905 folio_add_lru(folio);
3906
3907 /* To provide entry to swap_read_folio() */
3908 folio->swap = entry;
3909 swap_read_folio(folio, true, NULL);
3910 folio->private = NULL;
3911 }
3912 } else {
3913 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3914 vmf);
3915 if (page)
3916 folio = page_folio(page);
3917 swapcache = folio;
3918 }
3919
3920 if (!folio) {
3921 /*
3922 * Back out if somebody else faulted in this pte
3923 * while we released the pte lock.
3924 */
3925 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3926 vmf->address, &vmf->ptl);
3927 if (likely(vmf->pte &&
3928 pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
3929 ret = VM_FAULT_OOM;
3930 goto unlock;
3931 }
3932
3933 /* Had to read the page from swap area: Major fault */
3934 ret = VM_FAULT_MAJOR;
3935 count_vm_event(PGMAJFAULT);
3936 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3937 } else if (PageHWPoison(page)) {
3938 /*
3939 * hwpoisoned dirty swapcache pages are kept for killing
3940 * owner processes (which may be unknown at hwpoison time)
3941 */
3942 ret = VM_FAULT_HWPOISON;
3943 goto out_release;
3944 }
3945
3946 ret |= folio_lock_or_retry(folio, vmf);
3947 if (ret & VM_FAULT_RETRY)
3948 goto out_release;
3949
3950 if (swapcache) {
3951 /*
3952 * Make sure folio_free_swap() or swapoff did not release the
3953 * swapcache from under us. The page pin, and pte_same test
3954 * below, are not enough to exclude that. Even if it is still
3955 * swapcache, we need to check that the page's swap has not
3956 * changed.
3957 */
3958 if (unlikely(!folio_test_swapcache(folio) ||
3959 page_swap_entry(page).val != entry.val))
3960 goto out_page;
3961
3962 /*
3963 * KSM sometimes has to copy on read faults, for example, if
3964 * page->index of !PageKSM() pages would be nonlinear inside the
3965 * anon VMA -- PageKSM() is lost on actual swapout.
3966 */
3967 folio = ksm_might_need_to_copy(folio, vma, vmf->address);
3968 if (unlikely(!folio)) {
3969 ret = VM_FAULT_OOM;
3970 folio = swapcache;
3971 goto out_page;
3972 } else if (unlikely(folio == ERR_PTR(-EHWPOISON))) {
3973 ret = VM_FAULT_HWPOISON;
3974 folio = swapcache;
3975 goto out_page;
3976 }
3977 if (folio != swapcache)
3978 page = folio_page(folio, 0);
3979
3980 /*
3981 * If we want to map a page that's in the swapcache writable, we
3982 * have to detect via the refcount if we're really the exclusive
3983 * owner. Try removing the extra reference from the local LRU
3984 * caches if required.
3985 */
3986 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
3987 !folio_test_ksm(folio) && !folio_test_lru(folio))
3988 lru_add_drain();
3989 }
3990
3991 folio_throttle_swaprate(folio, GFP_KERNEL);
3992
3993 /*
3994 * Back out if somebody else already faulted in this pte.
3995 */
3996 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3997 &vmf->ptl);
3998 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
3999 goto out_nomap;
4000
4001 if (unlikely(!folio_test_uptodate(folio))) {
4002 ret = VM_FAULT_SIGBUS;
4003 goto out_nomap;
4004 }
4005
4006 /*
4007 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
4008 * must never point at an anonymous page in the swapcache that is
4009 * PG_anon_exclusive. Sanity check that this holds and especially, that
4010 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
4011 * check after taking the PT lock and making sure that nobody
4012 * concurrently faulted in this page and set PG_anon_exclusive.
4013 */
4014 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
4015 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
4016
4017 /*
4018 * Check under PT lock (to protect against concurrent fork() sharing
4019 * the swap entry concurrently) for certainly exclusive pages.
4020 */
4021 if (!folio_test_ksm(folio)) {
4022 exclusive = pte_swp_exclusive(vmf->orig_pte);
4023 if (folio != swapcache) {
4024 /*
4025 * We have a fresh page that is not exposed to the
4026 * swapcache -> certainly exclusive.
4027 */
4028 exclusive = true;
4029 } else if (exclusive && folio_test_writeback(folio) &&
4030 data_race(si->flags & SWP_STABLE_WRITES)) {
4031 /*
4032 * This is tricky: not all swap backends support
4033 * concurrent page modifications while under writeback.
4034 *
4035 * So if we stumble over such a page in the swapcache
4036 * we must not set the page exclusive, otherwise we can
4037 * map it writable without further checks and modify it
4038 * while still under writeback.
4039 *
4040 * For these problematic swap backends, simply drop the
4041 * exclusive marker: this is perfectly fine as we start
4042 * writeback only if we fully unmapped the page and
4043 * there are no unexpected references on the page after
4044 * unmapping succeeded. After fully unmapped, no
4045 * further GUP references (FOLL_GET and FOLL_PIN) can
4046 * appear, so dropping the exclusive marker and mapping
4047 * it only R/O is fine.
4048 */
4049 exclusive = false;
4050 }
4051 }
4052
4053 /*
4054 * Some architectures may have to restore extra metadata to the page
4055 * when reading from swap. This metadata may be indexed by swap entry
4056 * so this must be called before swap_free().
4057 */
4058 arch_swap_restore(entry, folio);
4059
4060 /*
4061 * Remove the swap entry and conditionally try to free up the swapcache.
4062 * We're already holding a reference on the page but haven't mapped it
4063 * yet.
4064 */
4065 swap_free(entry);
4066 if (should_try_to_free_swap(folio, vma, vmf->flags))
4067 folio_free_swap(folio);
4068
4069 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
4070 dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
4071 pte = mk_pte(page, vma->vm_page_prot);
4072
4073 /*
4074 * Same logic as in do_wp_page(); however, optimize for pages that are
4075 * certainly not shared either because we just allocated them without
4076 * exposing them to the swapcache or because the swap entry indicates
4077 * exclusivity.
4078 */
4079 if (!folio_test_ksm(folio) &&
4080 (exclusive || folio_ref_count(folio) == 1)) {
4081 if (vmf->flags & FAULT_FLAG_WRITE) {
4082 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
4083 vmf->flags &= ~FAULT_FLAG_WRITE;
4084 }
4085 rmap_flags |= RMAP_EXCLUSIVE;
4086 }
4087 flush_icache_page(vma, page);
4088 if (pte_swp_soft_dirty(vmf->orig_pte))
4089 pte = pte_mksoft_dirty(pte);
4090 if (pte_swp_uffd_wp(vmf->orig_pte))
4091 pte = pte_mkuffd_wp(pte);
4092 vmf->orig_pte = pte;
4093
4094 /* ksm created a completely new copy */
4095 if (unlikely(folio != swapcache && swapcache)) {
4096 folio_add_new_anon_rmap(folio, vma, vmf->address);
4097 folio_add_lru_vma(folio, vma);
4098 } else {
4099 folio_add_anon_rmap_pte(folio, page, vma, vmf->address,
4100 rmap_flags);
4101 }
4102
4103 VM_BUG_ON(!folio_test_anon(folio) ||
4104 (pte_write(pte) && !PageAnonExclusive(page)));
4105 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
4106 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
4107
4108 folio_unlock(folio);
4109 if (folio != swapcache && swapcache) {
4110 /*
4111 * Hold the lock to avoid the swap entry to be reused
4112 * until we take the PT lock for the pte_same() check
4113 * (to avoid false positives from pte_same). For
4114 * further safety release the lock after the swap_free
4115 * so that the swap count won't change under a
4116 * parallel locked swapcache.
4117 */
4118 folio_unlock(swapcache);
4119 folio_put(swapcache);
4120 }
4121
4122 if (vmf->flags & FAULT_FLAG_WRITE) {
4123 ret |= do_wp_page(vmf);
4124 if (ret & VM_FAULT_ERROR)
4125 ret &= VM_FAULT_ERROR;
4126 goto out;
4127 }
4128
4129 /* No need to invalidate - it was non-present before */
4130 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
4131unlock:
4132 if (vmf->pte)
4133 pte_unmap_unlock(vmf->pte, vmf->ptl);
4134out:
4135 /* Clear the swap cache pin for direct swapin after PTL unlock */
4136 if (need_clear_cache)
4137 swapcache_clear(si, entry);
4138 if (si)
4139 put_swap_device(si);
4140 return ret;
4141out_nomap:
4142 if (vmf->pte)
4143 pte_unmap_unlock(vmf->pte, vmf->ptl);
4144out_page:
4145 folio_unlock(folio);
4146out_release:
4147 folio_put(folio);
4148 if (folio != swapcache && swapcache) {
4149 folio_unlock(swapcache);
4150 folio_put(swapcache);
4151 }
4152 if (need_clear_cache)
4153 swapcache_clear(si, entry);
4154 if (si)
4155 put_swap_device(si);
4156 return ret;
4157}
4158
4159static bool pte_range_none(pte_t *pte, int nr_pages)
4160{
4161 int i;
4162
4163 for (i = 0; i < nr_pages; i++) {
4164 if (!pte_none(ptep_get_lockless(pte + i)))
4165 return false;
4166 }
4167
4168 return true;
4169}
4170
4171static struct folio *alloc_anon_folio(struct vm_fault *vmf)
4172{
4173#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4174 struct vm_area_struct *vma = vmf->vma;
4175 unsigned long orders;
4176 struct folio *folio;
4177 unsigned long addr;
4178 pte_t *pte;
4179 gfp_t gfp;
4180 int order;
4181
4182 /*
4183 * If uffd is active for the vma we need per-page fault fidelity to
4184 * maintain the uffd semantics.
4185 */
4186 if (unlikely(userfaultfd_armed(vma)))
4187 goto fallback;
4188
4189 /*
4190 * Get a list of all the (large) orders below PMD_ORDER that are enabled
4191 * for this vma. Then filter out the orders that can't be allocated over
4192 * the faulting address and still be fully contained in the vma.
4193 */
4194 orders = thp_vma_allowable_orders(vma, vma->vm_flags, false, true, true,
4195 BIT(PMD_ORDER) - 1);
4196 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
4197
4198 if (!orders)
4199 goto fallback;
4200
4201 pte = pte_offset_map(vmf->pmd, vmf->address & PMD_MASK);
4202 if (!pte)
4203 return ERR_PTR(-EAGAIN);
4204
4205 /*
4206 * Find the highest order where the aligned range is completely
4207 * pte_none(). Note that all remaining orders will be completely
4208 * pte_none().
4209 */
4210 order = highest_order(orders);
4211 while (orders) {
4212 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4213 if (pte_range_none(pte + pte_index(addr), 1 << order))
4214 break;
4215 order = next_order(&orders, order);
4216 }
4217
4218 pte_unmap(pte);
4219
4220 /* Try allocating the highest of the remaining orders. */
4221 gfp = vma_thp_gfp_mask(vma);
4222 while (orders) {
4223 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4224 folio = vma_alloc_folio(gfp, order, vma, addr, true);
4225 if (folio) {
4226 clear_huge_page(&folio->page, vmf->address, 1 << order);
4227 return folio;
4228 }
4229 order = next_order(&orders, order);
4230 }
4231
4232fallback:
4233#endif
4234 return vma_alloc_zeroed_movable_folio(vmf->vma, vmf->address);
4235}
4236
4237/*
4238 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4239 * but allow concurrent faults), and pte mapped but not yet locked.
4240 * We return with mmap_lock still held, but pte unmapped and unlocked.
4241 */
4242static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
4243{
4244 bool uffd_wp = vmf_orig_pte_uffd_wp(vmf);
4245 struct vm_area_struct *vma = vmf->vma;
4246 unsigned long addr = vmf->address;
4247 struct folio *folio;
4248 vm_fault_t ret = 0;
4249 int nr_pages = 1;
4250 pte_t entry;
4251 int i;
4252
4253 /* File mapping without ->vm_ops ? */
4254 if (vma->vm_flags & VM_SHARED)
4255 return VM_FAULT_SIGBUS;
4256
4257 /*
4258 * Use pte_alloc() instead of pte_alloc_map(), so that OOM can
4259 * be distinguished from a transient failure of pte_offset_map().
4260 */
4261 if (pte_alloc(vma->vm_mm, vmf->pmd))
4262 return VM_FAULT_OOM;
4263
4264 /* Use the zero-page for reads */
4265 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
4266 !mm_forbids_zeropage(vma->vm_mm)) {
4267 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
4268 vma->vm_page_prot));
4269 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4270 vmf->address, &vmf->ptl);
4271 if (!vmf->pte)
4272 goto unlock;
4273 if (vmf_pte_changed(vmf)) {
4274 update_mmu_tlb(vma, vmf->address, vmf->pte);
4275 goto unlock;
4276 }
4277 ret = check_stable_address_space(vma->vm_mm);
4278 if (ret)
4279 goto unlock;
4280 /* Deliver the page fault to userland, check inside PT lock */
4281 if (userfaultfd_missing(vma)) {
4282 pte_unmap_unlock(vmf->pte, vmf->ptl);
4283 return handle_userfault(vmf, VM_UFFD_MISSING);
4284 }
4285 goto setpte;
4286 }
4287
4288 /* Allocate our own private page. */
4289 if (unlikely(anon_vma_prepare(vma)))
4290 goto oom;
4291 /* Returns NULL on OOM or ERR_PTR(-EAGAIN) if we must retry the fault */
4292 folio = alloc_anon_folio(vmf);
4293 if (IS_ERR(folio))
4294 return 0;
4295 if (!folio)
4296 goto oom;
4297
4298 nr_pages = folio_nr_pages(folio);
4299 addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE);
4300
4301 if (mem_cgroup_charge(folio, vma->vm_mm, GFP_KERNEL))
4302 goto oom_free_page;
4303 folio_throttle_swaprate(folio, GFP_KERNEL);
4304
4305 /*
4306 * The memory barrier inside __folio_mark_uptodate makes sure that
4307 * preceding stores to the page contents become visible before
4308 * the set_pte_at() write.
4309 */
4310 __folio_mark_uptodate(folio);
4311
4312 entry = mk_pte(&folio->page, vma->vm_page_prot);
4313 entry = pte_sw_mkyoung(entry);
4314 if (vma->vm_flags & VM_WRITE)
4315 entry = pte_mkwrite(pte_mkdirty(entry), vma);
4316
4317 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
4318 if (!vmf->pte)
4319 goto release;
4320 if (nr_pages == 1 && vmf_pte_changed(vmf)) {
4321 update_mmu_tlb(vma, addr, vmf->pte);
4322 goto release;
4323 } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) {
4324 for (i = 0; i < nr_pages; i++)
4325 update_mmu_tlb(vma, addr + PAGE_SIZE * i, vmf->pte + i);
4326 goto release;
4327 }
4328
4329 ret = check_stable_address_space(vma->vm_mm);
4330 if (ret)
4331 goto release;
4332
4333 /* Deliver the page fault to userland, check inside PT lock */
4334 if (userfaultfd_missing(vma)) {
4335 pte_unmap_unlock(vmf->pte, vmf->ptl);
4336 folio_put(folio);
4337 return handle_userfault(vmf, VM_UFFD_MISSING);
4338 }
4339
4340 folio_ref_add(folio, nr_pages - 1);
4341 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4342 folio_add_new_anon_rmap(folio, vma, addr);
4343 folio_add_lru_vma(folio, vma);
4344setpte:
4345 if (uffd_wp)
4346 entry = pte_mkuffd_wp(entry);
4347 set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr_pages);
4348
4349 /* No need to invalidate - it was non-present before */
4350 update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr_pages);
4351unlock:
4352 if (vmf->pte)
4353 pte_unmap_unlock(vmf->pte, vmf->ptl);
4354 return ret;
4355release:
4356 folio_put(folio);
4357 goto unlock;
4358oom_free_page:
4359 folio_put(folio);
4360oom:
4361 return VM_FAULT_OOM;
4362}
4363
4364/*
4365 * The mmap_lock must have been held on entry, and may have been
4366 * released depending on flags and vma->vm_ops->fault() return value.
4367 * See filemap_fault() and __lock_page_retry().
4368 */
4369static vm_fault_t __do_fault(struct vm_fault *vmf)
4370{
4371 struct vm_area_struct *vma = vmf->vma;
4372 struct folio *folio;
4373 vm_fault_t ret;
4374
4375 /*
4376 * Preallocate pte before we take page_lock because this might lead to
4377 * deadlocks for memcg reclaim which waits for pages under writeback:
4378 * lock_page(A)
4379 * SetPageWriteback(A)
4380 * unlock_page(A)
4381 * lock_page(B)
4382 * lock_page(B)
4383 * pte_alloc_one
4384 * shrink_page_list
4385 * wait_on_page_writeback(A)
4386 * SetPageWriteback(B)
4387 * unlock_page(B)
4388 * # flush A, B to clear the writeback
4389 */
4390 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
4391 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4392 if (!vmf->prealloc_pte)
4393 return VM_FAULT_OOM;
4394 }
4395
4396 ret = vma->vm_ops->fault(vmf);
4397 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
4398 VM_FAULT_DONE_COW)))
4399 return ret;
4400
4401 folio = page_folio(vmf->page);
4402 if (unlikely(PageHWPoison(vmf->page))) {
4403 vm_fault_t poisonret = VM_FAULT_HWPOISON;
4404 if (ret & VM_FAULT_LOCKED) {
4405 if (page_mapped(vmf->page))
4406 unmap_mapping_folio(folio);
4407 /* Retry if a clean folio was removed from the cache. */
4408 if (mapping_evict_folio(folio->mapping, folio))
4409 poisonret = VM_FAULT_NOPAGE;
4410 folio_unlock(folio);
4411 }
4412 folio_put(folio);
4413 vmf->page = NULL;
4414 return poisonret;
4415 }
4416
4417 if (unlikely(!(ret & VM_FAULT_LOCKED)))
4418 folio_lock(folio);
4419 else
4420 VM_BUG_ON_PAGE(!folio_test_locked(folio), vmf->page);
4421
4422 return ret;
4423}
4424
4425#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4426static void deposit_prealloc_pte(struct vm_fault *vmf)
4427{
4428 struct vm_area_struct *vma = vmf->vma;
4429
4430 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
4431 /*
4432 * We are going to consume the prealloc table,
4433 * count that as nr_ptes.
4434 */
4435 mm_inc_nr_ptes(vma->vm_mm);
4436 vmf->prealloc_pte = NULL;
4437}
4438
4439vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4440{
4441 struct folio *folio = page_folio(page);
4442 struct vm_area_struct *vma = vmf->vma;
4443 bool write = vmf->flags & FAULT_FLAG_WRITE;
4444 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
4445 pmd_t entry;
4446 vm_fault_t ret = VM_FAULT_FALLBACK;
4447
4448 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
4449 return ret;
4450
4451 if (page != &folio->page || folio_order(folio) != HPAGE_PMD_ORDER)
4452 return ret;
4453
4454 /*
4455 * Just backoff if any subpage of a THP is corrupted otherwise
4456 * the corrupted page may mapped by PMD silently to escape the
4457 * check. This kind of THP just can be PTE mapped. Access to
4458 * the corrupted subpage should trigger SIGBUS as expected.
4459 */
4460 if (unlikely(folio_test_has_hwpoisoned(folio)))
4461 return ret;
4462
4463 /*
4464 * Archs like ppc64 need additional space to store information
4465 * related to pte entry. Use the preallocated table for that.
4466 */
4467 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
4468 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4469 if (!vmf->prealloc_pte)
4470 return VM_FAULT_OOM;
4471 }
4472
4473 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4474 if (unlikely(!pmd_none(*vmf->pmd)))
4475 goto out;
4476
4477 flush_icache_pages(vma, page, HPAGE_PMD_NR);
4478
4479 entry = mk_huge_pmd(page, vma->vm_page_prot);
4480 if (write)
4481 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
4482
4483 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
4484 folio_add_file_rmap_pmd(folio, page, vma);
4485
4486 /*
4487 * deposit and withdraw with pmd lock held
4488 */
4489 if (arch_needs_pgtable_deposit())
4490 deposit_prealloc_pte(vmf);
4491
4492 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
4493
4494 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
4495
4496 /* fault is handled */
4497 ret = 0;
4498 count_vm_event(THP_FILE_MAPPED);
4499out:
4500 spin_unlock(vmf->ptl);
4501 return ret;
4502}
4503#else
4504vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4505{
4506 return VM_FAULT_FALLBACK;
4507}
4508#endif
4509
4510/**
4511 * set_pte_range - Set a range of PTEs to point to pages in a folio.
4512 * @vmf: Fault decription.
4513 * @folio: The folio that contains @page.
4514 * @page: The first page to create a PTE for.
4515 * @nr: The number of PTEs to create.
4516 * @addr: The first address to create a PTE for.
4517 */
4518void set_pte_range(struct vm_fault *vmf, struct folio *folio,
4519 struct page *page, unsigned int nr, unsigned long addr)
4520{
4521 struct vm_area_struct *vma = vmf->vma;
4522 bool uffd_wp = vmf_orig_pte_uffd_wp(vmf);
4523 bool write = vmf->flags & FAULT_FLAG_WRITE;
4524 bool prefault = in_range(vmf->address, addr, nr * PAGE_SIZE);
4525 pte_t entry;
4526
4527 flush_icache_pages(vma, page, nr);
4528 entry = mk_pte(page, vma->vm_page_prot);
4529
4530 if (prefault && arch_wants_old_prefaulted_pte())
4531 entry = pte_mkold(entry);
4532 else
4533 entry = pte_sw_mkyoung(entry);
4534
4535 if (write)
4536 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
4537 if (unlikely(uffd_wp))
4538 entry = pte_mkuffd_wp(entry);
4539 /* copy-on-write page */
4540 if (write && !(vma->vm_flags & VM_SHARED)) {
4541 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr);
4542 VM_BUG_ON_FOLIO(nr != 1, folio);
4543 folio_add_new_anon_rmap(folio, vma, addr);
4544 folio_add_lru_vma(folio, vma);
4545 } else {
4546 add_mm_counter(vma->vm_mm, mm_counter_file(page), nr);
4547 folio_add_file_rmap_ptes(folio, page, nr, vma);
4548 }
4549 set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr);
4550
4551 /* no need to invalidate: a not-present page won't be cached */
4552 update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr);
4553}
4554
4555static bool vmf_pte_changed(struct vm_fault *vmf)
4556{
4557 if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)
4558 return !pte_same(ptep_get(vmf->pte), vmf->orig_pte);
4559
4560 return !pte_none(ptep_get(vmf->pte));
4561}
4562
4563/**
4564 * finish_fault - finish page fault once we have prepared the page to fault
4565 *
4566 * @vmf: structure describing the fault
4567 *
4568 * This function handles all that is needed to finish a page fault once the
4569 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
4570 * given page, adds reverse page mapping, handles memcg charges and LRU
4571 * addition.
4572 *
4573 * The function expects the page to be locked and on success it consumes a
4574 * reference of a page being mapped (for the PTE which maps it).
4575 *
4576 * Return: %0 on success, %VM_FAULT_ code in case of error.
4577 */
4578vm_fault_t finish_fault(struct vm_fault *vmf)
4579{
4580 struct vm_area_struct *vma = vmf->vma;
4581 struct page *page;
4582 vm_fault_t ret;
4583
4584 /* Did we COW the page? */
4585 if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
4586 page = vmf->cow_page;
4587 else
4588 page = vmf->page;
4589
4590 /*
4591 * check even for read faults because we might have lost our CoWed
4592 * page
4593 */
4594 if (!(vma->vm_flags & VM_SHARED)) {
4595 ret = check_stable_address_space(vma->vm_mm);
4596 if (ret)
4597 return ret;
4598 }
4599
4600 if (pmd_none(*vmf->pmd)) {
4601 if (PageTransCompound(page)) {
4602 ret = do_set_pmd(vmf, page);
4603 if (ret != VM_FAULT_FALLBACK)
4604 return ret;
4605 }
4606
4607 if (vmf->prealloc_pte)
4608 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
4609 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
4610 return VM_FAULT_OOM;
4611 }
4612
4613 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4614 vmf->address, &vmf->ptl);
4615 if (!vmf->pte)
4616 return VM_FAULT_NOPAGE;
4617
4618 /* Re-check under ptl */
4619 if (likely(!vmf_pte_changed(vmf))) {
4620 struct folio *folio = page_folio(page);
4621
4622 set_pte_range(vmf, folio, page, 1, vmf->address);
4623 ret = 0;
4624 } else {
4625 update_mmu_tlb(vma, vmf->address, vmf->pte);
4626 ret = VM_FAULT_NOPAGE;
4627 }
4628
4629 pte_unmap_unlock(vmf->pte, vmf->ptl);
4630 return ret;
4631}
4632
4633static unsigned long fault_around_pages __read_mostly =
4634 65536 >> PAGE_SHIFT;
4635
4636#ifdef CONFIG_DEBUG_FS
4637static int fault_around_bytes_get(void *data, u64 *val)
4638{
4639 *val = fault_around_pages << PAGE_SHIFT;
4640 return 0;
4641}
4642
4643/*
4644 * fault_around_bytes must be rounded down to the nearest page order as it's
4645 * what do_fault_around() expects to see.
4646 */
4647static int fault_around_bytes_set(void *data, u64 val)
4648{
4649 if (val / PAGE_SIZE > PTRS_PER_PTE)
4650 return -EINVAL;
4651
4652 /*
4653 * The minimum value is 1 page, however this results in no fault-around
4654 * at all. See should_fault_around().
4655 */
4656 fault_around_pages = max(rounddown_pow_of_two(val) >> PAGE_SHIFT, 1UL);
4657
4658 return 0;
4659}
4660DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
4661 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
4662
4663static int __init fault_around_debugfs(void)
4664{
4665 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
4666 &fault_around_bytes_fops);
4667 return 0;
4668}
4669late_initcall(fault_around_debugfs);
4670#endif
4671
4672/*
4673 * do_fault_around() tries to map few pages around the fault address. The hope
4674 * is that the pages will be needed soon and this will lower the number of
4675 * faults to handle.
4676 *
4677 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
4678 * not ready to be mapped: not up-to-date, locked, etc.
4679 *
4680 * This function doesn't cross VMA or page table boundaries, in order to call
4681 * map_pages() and acquire a PTE lock only once.
4682 *
4683 * fault_around_pages defines how many pages we'll try to map.
4684 * do_fault_around() expects it to be set to a power of two less than or equal
4685 * to PTRS_PER_PTE.
4686 *
4687 * The virtual address of the area that we map is naturally aligned to
4688 * fault_around_pages * PAGE_SIZE rounded down to the machine page size
4689 * (and therefore to page order). This way it's easier to guarantee
4690 * that we don't cross page table boundaries.
4691 */
4692static vm_fault_t do_fault_around(struct vm_fault *vmf)
4693{
4694 pgoff_t nr_pages = READ_ONCE(fault_around_pages);
4695 pgoff_t pte_off = pte_index(vmf->address);
4696 /* The page offset of vmf->address within the VMA. */
4697 pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff;
4698 pgoff_t from_pte, to_pte;
4699 vm_fault_t ret;
4700
4701 /* The PTE offset of the start address, clamped to the VMA. */
4702 from_pte = max(ALIGN_DOWN(pte_off, nr_pages),
4703 pte_off - min(pte_off, vma_off));
4704
4705 /* The PTE offset of the end address, clamped to the VMA and PTE. */
4706 to_pte = min3(from_pte + nr_pages, (pgoff_t)PTRS_PER_PTE,
4707 pte_off + vma_pages(vmf->vma) - vma_off) - 1;
4708
4709 if (pmd_none(*vmf->pmd)) {
4710 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
4711 if (!vmf->prealloc_pte)
4712 return VM_FAULT_OOM;
4713 }
4714
4715 rcu_read_lock();
4716 ret = vmf->vma->vm_ops->map_pages(vmf,
4717 vmf->pgoff + from_pte - pte_off,
4718 vmf->pgoff + to_pte - pte_off);
4719 rcu_read_unlock();
4720
4721 return ret;
4722}
4723
4724/* Return true if we should do read fault-around, false otherwise */
4725static inline bool should_fault_around(struct vm_fault *vmf)
4726{
4727 /* No ->map_pages? No way to fault around... */
4728 if (!vmf->vma->vm_ops->map_pages)
4729 return false;
4730
4731 if (uffd_disable_fault_around(vmf->vma))
4732 return false;
4733
4734 /* A single page implies no faulting 'around' at all. */
4735 return fault_around_pages > 1;
4736}
4737
4738static vm_fault_t do_read_fault(struct vm_fault *vmf)
4739{
4740 vm_fault_t ret = 0;
4741 struct folio *folio;
4742
4743 /*
4744 * Let's call ->map_pages() first and use ->fault() as fallback
4745 * if page by the offset is not ready to be mapped (cold cache or
4746 * something).
4747 */
4748 if (should_fault_around(vmf)) {
4749 ret = do_fault_around(vmf);
4750 if (ret)
4751 return ret;
4752 }
4753
4754 ret = vmf_can_call_fault(vmf);
4755 if (ret)
4756 return ret;
4757
4758 ret = __do_fault(vmf);
4759 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4760 return ret;
4761
4762 ret |= finish_fault(vmf);
4763 folio = page_folio(vmf->page);
4764 folio_unlock(folio);
4765 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4766 folio_put(folio);
4767 return ret;
4768}
4769
4770static vm_fault_t do_cow_fault(struct vm_fault *vmf)
4771{
4772 struct vm_area_struct *vma = vmf->vma;
4773 struct folio *folio;
4774 vm_fault_t ret;
4775
4776 ret = vmf_can_call_fault(vmf);
4777 if (!ret)
4778 ret = vmf_anon_prepare(vmf);
4779 if (ret)
4780 return ret;
4781
4782 folio = folio_prealloc(vma->vm_mm, vma, vmf->address, false);
4783 if (!folio)
4784 return VM_FAULT_OOM;
4785
4786 vmf->cow_page = &folio->page;
4787
4788 ret = __do_fault(vmf);
4789 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4790 goto uncharge_out;
4791 if (ret & VM_FAULT_DONE_COW)
4792 return ret;
4793
4794 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
4795 __folio_mark_uptodate(folio);
4796
4797 ret |= finish_fault(vmf);
4798 unlock_page(vmf->page);
4799 put_page(vmf->page);
4800 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4801 goto uncharge_out;
4802 return ret;
4803uncharge_out:
4804 folio_put(folio);
4805 return ret;
4806}
4807
4808static vm_fault_t do_shared_fault(struct vm_fault *vmf)
4809{
4810 struct vm_area_struct *vma = vmf->vma;
4811 vm_fault_t ret, tmp;
4812 struct folio *folio;
4813
4814 ret = vmf_can_call_fault(vmf);
4815 if (ret)
4816 return ret;
4817
4818 ret = __do_fault(vmf);
4819 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4820 return ret;
4821
4822 folio = page_folio(vmf->page);
4823
4824 /*
4825 * Check if the backing address space wants to know that the page is
4826 * about to become writable
4827 */
4828 if (vma->vm_ops->page_mkwrite) {
4829 folio_unlock(folio);
4830 tmp = do_page_mkwrite(vmf, folio);
4831 if (unlikely(!tmp ||
4832 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
4833 folio_put(folio);
4834 return tmp;
4835 }
4836 }
4837
4838 ret |= finish_fault(vmf);
4839 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
4840 VM_FAULT_RETRY))) {
4841 folio_unlock(folio);
4842 folio_put(folio);
4843 return ret;
4844 }
4845
4846 ret |= fault_dirty_shared_page(vmf);
4847 return ret;
4848}
4849
4850/*
4851 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4852 * but allow concurrent faults).
4853 * The mmap_lock may have been released depending on flags and our
4854 * return value. See filemap_fault() and __folio_lock_or_retry().
4855 * If mmap_lock is released, vma may become invalid (for example
4856 * by other thread calling munmap()).
4857 */
4858static vm_fault_t do_fault(struct vm_fault *vmf)
4859{
4860 struct vm_area_struct *vma = vmf->vma;
4861 struct mm_struct *vm_mm = vma->vm_mm;
4862 vm_fault_t ret;
4863
4864 /*
4865 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4866 */
4867 if (!vma->vm_ops->fault) {
4868 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
4869 vmf->address, &vmf->ptl);
4870 if (unlikely(!vmf->pte))
4871 ret = VM_FAULT_SIGBUS;
4872 else {
4873 /*
4874 * Make sure this is not a temporary clearing of pte
4875 * by holding ptl and checking again. A R/M/W update
4876 * of pte involves: take ptl, clearing the pte so that
4877 * we don't have concurrent modification by hardware
4878 * followed by an update.
4879 */
4880 if (unlikely(pte_none(ptep_get(vmf->pte))))
4881 ret = VM_FAULT_SIGBUS;
4882 else
4883 ret = VM_FAULT_NOPAGE;
4884
4885 pte_unmap_unlock(vmf->pte, vmf->ptl);
4886 }
4887 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
4888 ret = do_read_fault(vmf);
4889 else if (!(vma->vm_flags & VM_SHARED))
4890 ret = do_cow_fault(vmf);
4891 else
4892 ret = do_shared_fault(vmf);
4893
4894 /* preallocated pagetable is unused: free it */
4895 if (vmf->prealloc_pte) {
4896 pte_free(vm_mm, vmf->prealloc_pte);
4897 vmf->prealloc_pte = NULL;
4898 }
4899 return ret;
4900}
4901
4902int numa_migrate_prep(struct folio *folio, struct vm_area_struct *vma,
4903 unsigned long addr, int page_nid, int *flags)
4904{
4905 folio_get(folio);
4906
4907 /* Record the current PID acceesing VMA */
4908 vma_set_access_pid_bit(vma);
4909
4910 count_vm_numa_event(NUMA_HINT_FAULTS);
4911 if (page_nid == numa_node_id()) {
4912 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
4913 *flags |= TNF_FAULT_LOCAL;
4914 }
4915
4916 return mpol_misplaced(folio, vma, addr);
4917}
4918
4919static vm_fault_t do_numa_page(struct vm_fault *vmf)
4920{
4921 struct vm_area_struct *vma = vmf->vma;
4922 struct folio *folio = NULL;
4923 int nid = NUMA_NO_NODE;
4924 bool writable = false;
4925 int last_cpupid;
4926 int target_nid;
4927 pte_t pte, old_pte;
4928 int flags = 0;
4929
4930 /*
4931 * The "pte" at this point cannot be used safely without
4932 * validation through pte_unmap_same(). It's of NUMA type but
4933 * the pfn may be screwed if the read is non atomic.
4934 */
4935 spin_lock(vmf->ptl);
4936 if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
4937 pte_unmap_unlock(vmf->pte, vmf->ptl);
4938 goto out;
4939 }
4940
4941 /* Get the normal PTE */
4942 old_pte = ptep_get(vmf->pte);
4943 pte = pte_modify(old_pte, vma->vm_page_prot);
4944
4945 /*
4946 * Detect now whether the PTE could be writable; this information
4947 * is only valid while holding the PT lock.
4948 */
4949 writable = pte_write(pte);
4950 if (!writable && vma_wants_manual_pte_write_upgrade(vma) &&
4951 can_change_pte_writable(vma, vmf->address, pte))
4952 writable = true;
4953
4954 folio = vm_normal_folio(vma, vmf->address, pte);
4955 if (!folio || folio_is_zone_device(folio))
4956 goto out_map;
4957
4958 /* TODO: handle PTE-mapped THP */
4959 if (folio_test_large(folio))
4960 goto out_map;
4961
4962 /*
4963 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4964 * much anyway since they can be in shared cache state. This misses
4965 * the case where a mapping is writable but the process never writes
4966 * to it but pte_write gets cleared during protection updates and
4967 * pte_dirty has unpredictable behaviour between PTE scan updates,
4968 * background writeback, dirty balancing and application behaviour.
4969 */
4970 if (!writable)
4971 flags |= TNF_NO_GROUP;
4972
4973 /*
4974 * Flag if the folio is shared between multiple address spaces. This
4975 * is later used when determining whether to group tasks together
4976 */
4977 if (folio_estimated_sharers(folio) > 1 && (vma->vm_flags & VM_SHARED))
4978 flags |= TNF_SHARED;
4979
4980 nid = folio_nid(folio);
4981 /*
4982 * For memory tiering mode, cpupid of slow memory page is used
4983 * to record page access time. So use default value.
4984 */
4985 if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
4986 !node_is_toptier(nid))
4987 last_cpupid = (-1 & LAST_CPUPID_MASK);
4988 else
4989 last_cpupid = folio_last_cpupid(folio);
4990 target_nid = numa_migrate_prep(folio, vma, vmf->address, nid, &flags);
4991 if (target_nid == NUMA_NO_NODE) {
4992 folio_put(folio);
4993 goto out_map;
4994 }
4995 pte_unmap_unlock(vmf->pte, vmf->ptl);
4996 writable = false;
4997
4998 /* Migrate to the requested node */
4999 if (migrate_misplaced_folio(folio, vma, target_nid)) {
5000 nid = target_nid;
5001 flags |= TNF_MIGRATED;
5002 } else {
5003 flags |= TNF_MIGRATE_FAIL;
5004 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
5005 vmf->address, &vmf->ptl);
5006 if (unlikely(!vmf->pte))
5007 goto out;
5008 if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
5009 pte_unmap_unlock(vmf->pte, vmf->ptl);
5010 goto out;
5011 }
5012 goto out_map;
5013 }
5014
5015out:
5016 if (nid != NUMA_NO_NODE)
5017 task_numa_fault(last_cpupid, nid, 1, flags);
5018 return 0;
5019out_map:
5020 /*
5021 * Make it present again, depending on how arch implements
5022 * non-accessible ptes, some can allow access by kernel mode.
5023 */
5024 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
5025 pte = pte_modify(old_pte, vma->vm_page_prot);
5026 pte = pte_mkyoung(pte);
5027 if (writable)
5028 pte = pte_mkwrite(pte, vma);
5029 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
5030 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
5031 pte_unmap_unlock(vmf->pte, vmf->ptl);
5032 goto out;
5033}
5034
5035static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
5036{
5037 struct vm_area_struct *vma = vmf->vma;
5038 if (vma_is_anonymous(vma))
5039 return do_huge_pmd_anonymous_page(vmf);
5040 if (vma->vm_ops->huge_fault)
5041 return vma->vm_ops->huge_fault(vmf, PMD_ORDER);
5042 return VM_FAULT_FALLBACK;
5043}
5044
5045/* `inline' is required to avoid gcc 4.1.2 build error */
5046static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
5047{
5048 struct vm_area_struct *vma = vmf->vma;
5049 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
5050 vm_fault_t ret;
5051
5052 if (vma_is_anonymous(vma)) {
5053 if (likely(!unshare) &&
5054 userfaultfd_huge_pmd_wp(vma, vmf->orig_pmd)) {
5055 if (userfaultfd_wp_async(vmf->vma))
5056 goto split;
5057 return handle_userfault(vmf, VM_UFFD_WP);
5058 }
5059 return do_huge_pmd_wp_page(vmf);
5060 }
5061
5062 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
5063 if (vma->vm_ops->huge_fault) {
5064 ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER);
5065 if (!(ret & VM_FAULT_FALLBACK))
5066 return ret;
5067 }
5068 }
5069
5070split:
5071 /* COW or write-notify handled on pte level: split pmd. */
5072 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
5073
5074 return VM_FAULT_FALLBACK;
5075}
5076
5077static vm_fault_t create_huge_pud(struct vm_fault *vmf)
5078{
5079#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
5080 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
5081 struct vm_area_struct *vma = vmf->vma;
5082 /* No support for anonymous transparent PUD pages yet */
5083 if (vma_is_anonymous(vma))
5084 return VM_FAULT_FALLBACK;
5085 if (vma->vm_ops->huge_fault)
5086 return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
5087#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
5088 return VM_FAULT_FALLBACK;
5089}
5090
5091static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
5092{
5093#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
5094 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
5095 struct vm_area_struct *vma = vmf->vma;
5096 vm_fault_t ret;
5097
5098 /* No support for anonymous transparent PUD pages yet */
5099 if (vma_is_anonymous(vma))
5100 goto split;
5101 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
5102 if (vma->vm_ops->huge_fault) {
5103 ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER);
5104 if (!(ret & VM_FAULT_FALLBACK))
5105 return ret;
5106 }
5107 }
5108split:
5109 /* COW or write-notify not handled on PUD level: split pud.*/
5110 __split_huge_pud(vma, vmf->pud, vmf->address);
5111#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
5112 return VM_FAULT_FALLBACK;
5113}
5114
5115/*
5116 * These routines also need to handle stuff like marking pages dirty
5117 * and/or accessed for architectures that don't do it in hardware (most
5118 * RISC architectures). The early dirtying is also good on the i386.
5119 *
5120 * There is also a hook called "update_mmu_cache()" that architectures
5121 * with external mmu caches can use to update those (ie the Sparc or
5122 * PowerPC hashed page tables that act as extended TLBs).
5123 *
5124 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
5125 * concurrent faults).
5126 *
5127 * The mmap_lock may have been released depending on flags and our return value.
5128 * See filemap_fault() and __folio_lock_or_retry().
5129 */
5130static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
5131{
5132 pte_t entry;
5133
5134 if (unlikely(pmd_none(*vmf->pmd))) {
5135 /*
5136 * Leave __pte_alloc() until later: because vm_ops->fault may
5137 * want to allocate huge page, and if we expose page table
5138 * for an instant, it will be difficult to retract from
5139 * concurrent faults and from rmap lookups.
5140 */
5141 vmf->pte = NULL;
5142 vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID;
5143 } else {
5144 /*
5145 * A regular pmd is established and it can't morph into a huge
5146 * pmd by anon khugepaged, since that takes mmap_lock in write
5147 * mode; but shmem or file collapse to THP could still morph
5148 * it into a huge pmd: just retry later if so.
5149 */
5150 vmf->pte = pte_offset_map_nolock(vmf->vma->vm_mm, vmf->pmd,
5151 vmf->address, &vmf->ptl);
5152 if (unlikely(!vmf->pte))
5153 return 0;
5154 vmf->orig_pte = ptep_get_lockless(vmf->pte);
5155 vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID;
5156
5157 if (pte_none(vmf->orig_pte)) {
5158 pte_unmap(vmf->pte);
5159 vmf->pte = NULL;
5160 }
5161 }
5162
5163 if (!vmf->pte)
5164 return do_pte_missing(vmf);
5165
5166 if (!pte_present(vmf->orig_pte))
5167 return do_swap_page(vmf);
5168
5169 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
5170 return do_numa_page(vmf);
5171
5172 spin_lock(vmf->ptl);
5173 entry = vmf->orig_pte;
5174 if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) {
5175 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
5176 goto unlock;
5177 }
5178 if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
5179 if (!pte_write(entry))
5180 return do_wp_page(vmf);
5181 else if (likely(vmf->flags & FAULT_FLAG_WRITE))
5182 entry = pte_mkdirty(entry);
5183 }
5184 entry = pte_mkyoung(entry);
5185 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
5186 vmf->flags & FAULT_FLAG_WRITE)) {
5187 update_mmu_cache_range(vmf, vmf->vma, vmf->address,
5188 vmf->pte, 1);
5189 } else {
5190 /* Skip spurious TLB flush for retried page fault */
5191 if (vmf->flags & FAULT_FLAG_TRIED)
5192 goto unlock;
5193 /*
5194 * This is needed only for protection faults but the arch code
5195 * is not yet telling us if this is a protection fault or not.
5196 * This still avoids useless tlb flushes for .text page faults
5197 * with threads.
5198 */
5199 if (vmf->flags & FAULT_FLAG_WRITE)
5200 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address,
5201 vmf->pte);
5202 }
5203unlock:
5204 pte_unmap_unlock(vmf->pte, vmf->ptl);
5205 return 0;
5206}
5207
5208/*
5209 * On entry, we hold either the VMA lock or the mmap_lock
5210 * (FAULT_FLAG_VMA_LOCK tells you which). If VM_FAULT_RETRY is set in
5211 * the result, the mmap_lock is not held on exit. See filemap_fault()
5212 * and __folio_lock_or_retry().
5213 */
5214static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
5215 unsigned long address, unsigned int flags)
5216{
5217 struct vm_fault vmf = {
5218 .vma = vma,
5219 .address = address & PAGE_MASK,
5220 .real_address = address,
5221 .flags = flags,
5222 .pgoff = linear_page_index(vma, address),
5223 .gfp_mask = __get_fault_gfp_mask(vma),
5224 };
5225 struct mm_struct *mm = vma->vm_mm;
5226 unsigned long vm_flags = vma->vm_flags;
5227 pgd_t *pgd;
5228 p4d_t *p4d;
5229 vm_fault_t ret;
5230
5231 pgd = pgd_offset(mm, address);
5232 p4d = p4d_alloc(mm, pgd, address);
5233 if (!p4d)
5234 return VM_FAULT_OOM;
5235
5236 vmf.pud = pud_alloc(mm, p4d, address);
5237 if (!vmf.pud)
5238 return VM_FAULT_OOM;
5239retry_pud:
5240 if (pud_none(*vmf.pud) &&
5241 thp_vma_allowable_order(vma, vm_flags, false, true, true, PUD_ORDER)) {
5242 ret = create_huge_pud(&vmf);
5243 if (!(ret & VM_FAULT_FALLBACK))
5244 return ret;
5245 } else {
5246 pud_t orig_pud = *vmf.pud;
5247
5248 barrier();
5249 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
5250
5251 /*
5252 * TODO once we support anonymous PUDs: NUMA case and
5253 * FAULT_FLAG_UNSHARE handling.
5254 */
5255 if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) {
5256 ret = wp_huge_pud(&vmf, orig_pud);
5257 if (!(ret & VM_FAULT_FALLBACK))
5258 return ret;
5259 } else {
5260 huge_pud_set_accessed(&vmf, orig_pud);
5261 return 0;
5262 }
5263 }
5264 }
5265
5266 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
5267 if (!vmf.pmd)
5268 return VM_FAULT_OOM;
5269
5270 /* Huge pud page fault raced with pmd_alloc? */
5271 if (pud_trans_unstable(vmf.pud))
5272 goto retry_pud;
5273
5274 if (pmd_none(*vmf.pmd) &&
5275 thp_vma_allowable_order(vma, vm_flags, false, true, true, PMD_ORDER)) {
5276 ret = create_huge_pmd(&vmf);
5277 if (!(ret & VM_FAULT_FALLBACK))
5278 return ret;
5279 } else {
5280 vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
5281
5282 if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
5283 VM_BUG_ON(thp_migration_supported() &&
5284 !is_pmd_migration_entry(vmf.orig_pmd));
5285 if (is_pmd_migration_entry(vmf.orig_pmd))
5286 pmd_migration_entry_wait(mm, vmf.pmd);
5287 return 0;
5288 }
5289 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
5290 if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
5291 return do_huge_pmd_numa_page(&vmf);
5292
5293 if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
5294 !pmd_write(vmf.orig_pmd)) {
5295 ret = wp_huge_pmd(&vmf);
5296 if (!(ret & VM_FAULT_FALLBACK))
5297 return ret;
5298 } else {
5299 huge_pmd_set_accessed(&vmf);
5300 return 0;
5301 }
5302 }
5303 }
5304
5305 return handle_pte_fault(&vmf);
5306}
5307
5308/**
5309 * mm_account_fault - Do page fault accounting
5310 * @mm: mm from which memcg should be extracted. It can be NULL.
5311 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
5312 * of perf event counters, but we'll still do the per-task accounting to
5313 * the task who triggered this page fault.
5314 * @address: the faulted address.
5315 * @flags: the fault flags.
5316 * @ret: the fault retcode.
5317 *
5318 * This will take care of most of the page fault accounting. Meanwhile, it
5319 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
5320 * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
5321 * still be in per-arch page fault handlers at the entry of page fault.
5322 */
5323static inline void mm_account_fault(struct mm_struct *mm, struct pt_regs *regs,
5324 unsigned long address, unsigned int flags,
5325 vm_fault_t ret)
5326{
5327 bool major;
5328
5329 /* Incomplete faults will be accounted upon completion. */
5330 if (ret & VM_FAULT_RETRY)
5331 return;
5332
5333 /*
5334 * To preserve the behavior of older kernels, PGFAULT counters record
5335 * both successful and failed faults, as opposed to perf counters,
5336 * which ignore failed cases.
5337 */
5338 count_vm_event(PGFAULT);
5339 count_memcg_event_mm(mm, PGFAULT);
5340
5341 /*
5342 * Do not account for unsuccessful faults (e.g. when the address wasn't
5343 * valid). That includes arch_vma_access_permitted() failing before
5344 * reaching here. So this is not a "this many hardware page faults"
5345 * counter. We should use the hw profiling for that.
5346 */
5347 if (ret & VM_FAULT_ERROR)
5348 return;
5349
5350 /*
5351 * We define the fault as a major fault when the final successful fault
5352 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
5353 * handle it immediately previously).
5354 */
5355 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
5356
5357 if (major)
5358 current->maj_flt++;
5359 else
5360 current->min_flt++;
5361
5362 /*
5363 * If the fault is done for GUP, regs will be NULL. We only do the
5364 * accounting for the per thread fault counters who triggered the
5365 * fault, and we skip the perf event updates.
5366 */
5367 if (!regs)
5368 return;
5369
5370 if (major)
5371 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
5372 else
5373 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
5374}
5375
5376#ifdef CONFIG_LRU_GEN
5377static void lru_gen_enter_fault(struct vm_area_struct *vma)
5378{
5379 /* the LRU algorithm only applies to accesses with recency */
5380 current->in_lru_fault = vma_has_recency(vma);
5381}
5382
5383static void lru_gen_exit_fault(void)
5384{
5385 current->in_lru_fault = false;
5386}
5387#else
5388static void lru_gen_enter_fault(struct vm_area_struct *vma)
5389{
5390}
5391
5392static void lru_gen_exit_fault(void)
5393{
5394}
5395#endif /* CONFIG_LRU_GEN */
5396
5397static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma,
5398 unsigned int *flags)
5399{
5400 if (unlikely(*flags & FAULT_FLAG_UNSHARE)) {
5401 if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE))
5402 return VM_FAULT_SIGSEGV;
5403 /*
5404 * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's
5405 * just treat it like an ordinary read-fault otherwise.
5406 */
5407 if (!is_cow_mapping(vma->vm_flags))
5408 *flags &= ~FAULT_FLAG_UNSHARE;
5409 } else if (*flags & FAULT_FLAG_WRITE) {
5410 /* Write faults on read-only mappings are impossible ... */
5411 if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE)))
5412 return VM_FAULT_SIGSEGV;
5413 /* ... and FOLL_FORCE only applies to COW mappings. */
5414 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) &&
5415 !is_cow_mapping(vma->vm_flags)))
5416 return VM_FAULT_SIGSEGV;
5417 }
5418#ifdef CONFIG_PER_VMA_LOCK
5419 /*
5420 * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of
5421 * the assumption that lock is dropped on VM_FAULT_RETRY.
5422 */
5423 if (WARN_ON_ONCE((*flags &
5424 (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) ==
5425 (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)))
5426 return VM_FAULT_SIGSEGV;
5427#endif
5428
5429 return 0;
5430}
5431
5432/*
5433 * By the time we get here, we already hold the mm semaphore
5434 *
5435 * The mmap_lock may have been released depending on flags and our
5436 * return value. See filemap_fault() and __folio_lock_or_retry().
5437 */
5438vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
5439 unsigned int flags, struct pt_regs *regs)
5440{
5441 /* If the fault handler drops the mmap_lock, vma may be freed */
5442 struct mm_struct *mm = vma->vm_mm;
5443 vm_fault_t ret;
5444
5445 __set_current_state(TASK_RUNNING);
5446
5447 ret = sanitize_fault_flags(vma, &flags);
5448 if (ret)
5449 goto out;
5450
5451 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
5452 flags & FAULT_FLAG_INSTRUCTION,
5453 flags & FAULT_FLAG_REMOTE)) {
5454 ret = VM_FAULT_SIGSEGV;
5455 goto out;
5456 }
5457
5458 /*
5459 * Enable the memcg OOM handling for faults triggered in user
5460 * space. Kernel faults are handled more gracefully.
5461 */
5462 if (flags & FAULT_FLAG_USER)
5463 mem_cgroup_enter_user_fault();
5464
5465 lru_gen_enter_fault(vma);
5466
5467 if (unlikely(is_vm_hugetlb_page(vma)))
5468 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
5469 else
5470 ret = __handle_mm_fault(vma, address, flags);
5471
5472 lru_gen_exit_fault();
5473
5474 if (flags & FAULT_FLAG_USER) {
5475 mem_cgroup_exit_user_fault();
5476 /*
5477 * The task may have entered a memcg OOM situation but
5478 * if the allocation error was handled gracefully (no
5479 * VM_FAULT_OOM), there is no need to kill anything.
5480 * Just clean up the OOM state peacefully.
5481 */
5482 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
5483 mem_cgroup_oom_synchronize(false);
5484 }
5485out:
5486 mm_account_fault(mm, regs, address, flags, ret);
5487
5488 return ret;
5489}
5490EXPORT_SYMBOL_GPL(handle_mm_fault);
5491
5492#ifdef CONFIG_LOCK_MM_AND_FIND_VMA
5493#include <linux/extable.h>
5494
5495static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
5496{
5497 if (likely(mmap_read_trylock(mm)))
5498 return true;
5499
5500 if (regs && !user_mode(regs)) {
5501 unsigned long ip = exception_ip(regs);
5502 if (!search_exception_tables(ip))
5503 return false;
5504 }
5505
5506 return !mmap_read_lock_killable(mm);
5507}
5508
5509static inline bool mmap_upgrade_trylock(struct mm_struct *mm)
5510{
5511 /*
5512 * We don't have this operation yet.
5513 *
5514 * It should be easy enough to do: it's basically a
5515 * atomic_long_try_cmpxchg_acquire()
5516 * from RWSEM_READER_BIAS -> RWSEM_WRITER_LOCKED, but
5517 * it also needs the proper lockdep magic etc.
5518 */
5519 return false;
5520}
5521
5522static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
5523{
5524 mmap_read_unlock(mm);
5525 if (regs && !user_mode(regs)) {
5526 unsigned long ip = exception_ip(regs);
5527 if (!search_exception_tables(ip))
5528 return false;
5529 }
5530 return !mmap_write_lock_killable(mm);
5531}
5532
5533/*
5534 * Helper for page fault handling.
5535 *
5536 * This is kind of equivalend to "mmap_read_lock()" followed
5537 * by "find_extend_vma()", except it's a lot more careful about
5538 * the locking (and will drop the lock on failure).
5539 *
5540 * For example, if we have a kernel bug that causes a page
5541 * fault, we don't want to just use mmap_read_lock() to get
5542 * the mm lock, because that would deadlock if the bug were
5543 * to happen while we're holding the mm lock for writing.
5544 *
5545 * So this checks the exception tables on kernel faults in
5546 * order to only do this all for instructions that are actually
5547 * expected to fault.
5548 *
5549 * We can also actually take the mm lock for writing if we
5550 * need to extend the vma, which helps the VM layer a lot.
5551 */
5552struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
5553 unsigned long addr, struct pt_regs *regs)
5554{
5555 struct vm_area_struct *vma;
5556
5557 if (!get_mmap_lock_carefully(mm, regs))
5558 return NULL;
5559
5560 vma = find_vma(mm, addr);
5561 if (likely(vma && (vma->vm_start <= addr)))
5562 return vma;
5563
5564 /*
5565 * Well, dang. We might still be successful, but only
5566 * if we can extend a vma to do so.
5567 */
5568 if (!vma || !(vma->vm_flags & VM_GROWSDOWN)) {
5569 mmap_read_unlock(mm);
5570 return NULL;
5571 }
5572
5573 /*
5574 * We can try to upgrade the mmap lock atomically,
5575 * in which case we can continue to use the vma
5576 * we already looked up.
5577 *
5578 * Otherwise we'll have to drop the mmap lock and
5579 * re-take it, and also look up the vma again,
5580 * re-checking it.
5581 */
5582 if (!mmap_upgrade_trylock(mm)) {
5583 if (!upgrade_mmap_lock_carefully(mm, regs))
5584 return NULL;
5585
5586 vma = find_vma(mm, addr);
5587 if (!vma)
5588 goto fail;
5589 if (vma->vm_start <= addr)
5590 goto success;
5591 if (!(vma->vm_flags & VM_GROWSDOWN))
5592 goto fail;
5593 }
5594
5595 if (expand_stack_locked(vma, addr))
5596 goto fail;
5597
5598success:
5599 mmap_write_downgrade(mm);
5600 return vma;
5601
5602fail:
5603 mmap_write_unlock(mm);
5604 return NULL;
5605}
5606#endif
5607
5608#ifdef CONFIG_PER_VMA_LOCK
5609/*
5610 * Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be
5611 * stable and not isolated. If the VMA is not found or is being modified the
5612 * function returns NULL.
5613 */
5614struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
5615 unsigned long address)
5616{
5617 MA_STATE(mas, &mm->mm_mt, address, address);
5618 struct vm_area_struct *vma;
5619
5620 rcu_read_lock();
5621retry:
5622 vma = mas_walk(&mas);
5623 if (!vma)
5624 goto inval;
5625
5626 if (!vma_start_read(vma))
5627 goto inval;
5628
5629 /*
5630 * find_mergeable_anon_vma uses adjacent vmas which are not locked.
5631 * This check must happen after vma_start_read(); otherwise, a
5632 * concurrent mremap() with MREMAP_DONTUNMAP could dissociate the VMA
5633 * from its anon_vma.
5634 */
5635 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma))
5636 goto inval_end_read;
5637
5638 /* Check since vm_start/vm_end might change before we lock the VMA */
5639 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
5640 goto inval_end_read;
5641
5642 /* Check if the VMA got isolated after we found it */
5643 if (vma->detached) {
5644 vma_end_read(vma);
5645 count_vm_vma_lock_event(VMA_LOCK_MISS);
5646 /* The area was replaced with another one */
5647 goto retry;
5648 }
5649
5650 rcu_read_unlock();
5651 return vma;
5652
5653inval_end_read:
5654 vma_end_read(vma);
5655inval:
5656 rcu_read_unlock();
5657 count_vm_vma_lock_event(VMA_LOCK_ABORT);
5658 return NULL;
5659}
5660#endif /* CONFIG_PER_VMA_LOCK */
5661
5662#ifndef __PAGETABLE_P4D_FOLDED
5663/*
5664 * Allocate p4d page table.
5665 * We've already handled the fast-path in-line.
5666 */
5667int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
5668{
5669 p4d_t *new = p4d_alloc_one(mm, address);
5670 if (!new)
5671 return -ENOMEM;
5672
5673 spin_lock(&mm->page_table_lock);
5674 if (pgd_present(*pgd)) { /* Another has populated it */
5675 p4d_free(mm, new);
5676 } else {
5677 smp_wmb(); /* See comment in pmd_install() */
5678 pgd_populate(mm, pgd, new);
5679 }
5680 spin_unlock(&mm->page_table_lock);
5681 return 0;
5682}
5683#endif /* __PAGETABLE_P4D_FOLDED */
5684
5685#ifndef __PAGETABLE_PUD_FOLDED
5686/*
5687 * Allocate page upper directory.
5688 * We've already handled the fast-path in-line.
5689 */
5690int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
5691{
5692 pud_t *new = pud_alloc_one(mm, address);
5693 if (!new)
5694 return -ENOMEM;
5695
5696 spin_lock(&mm->page_table_lock);
5697 if (!p4d_present(*p4d)) {
5698 mm_inc_nr_puds(mm);
5699 smp_wmb(); /* See comment in pmd_install() */
5700 p4d_populate(mm, p4d, new);
5701 } else /* Another has populated it */
5702 pud_free(mm, new);
5703 spin_unlock(&mm->page_table_lock);
5704 return 0;
5705}
5706#endif /* __PAGETABLE_PUD_FOLDED */
5707
5708#ifndef __PAGETABLE_PMD_FOLDED
5709/*
5710 * Allocate page middle directory.
5711 * We've already handled the fast-path in-line.
5712 */
5713int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
5714{
5715 spinlock_t *ptl;
5716 pmd_t *new = pmd_alloc_one(mm, address);
5717 if (!new)
5718 return -ENOMEM;
5719
5720 ptl = pud_lock(mm, pud);
5721 if (!pud_present(*pud)) {
5722 mm_inc_nr_pmds(mm);
5723 smp_wmb(); /* See comment in pmd_install() */
5724 pud_populate(mm, pud, new);
5725 } else { /* Another has populated it */
5726 pmd_free(mm, new);
5727 }
5728 spin_unlock(ptl);
5729 return 0;
5730}
5731#endif /* __PAGETABLE_PMD_FOLDED */
5732
5733/**
5734 * follow_pte - look up PTE at a user virtual address
5735 * @mm: the mm_struct of the target address space
5736 * @address: user virtual address
5737 * @ptepp: location to store found PTE
5738 * @ptlp: location to store the lock for the PTE
5739 *
5740 * On a successful return, the pointer to the PTE is stored in @ptepp;
5741 * the corresponding lock is taken and its location is stored in @ptlp.
5742 * The contents of the PTE are only stable until @ptlp is released;
5743 * any further use, if any, must be protected against invalidation
5744 * with MMU notifiers.
5745 *
5746 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
5747 * should be taken for read.
5748 *
5749 * KVM uses this function. While it is arguably less bad than ``follow_pfn``,
5750 * it is not a good general-purpose API.
5751 *
5752 * Return: zero on success, -ve otherwise.
5753 */
5754int follow_pte(struct mm_struct *mm, unsigned long address,
5755 pte_t **ptepp, spinlock_t **ptlp)
5756{
5757 pgd_t *pgd;
5758 p4d_t *p4d;
5759 pud_t *pud;
5760 pmd_t *pmd;
5761 pte_t *ptep;
5762
5763 pgd = pgd_offset(mm, address);
5764 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
5765 goto out;
5766
5767 p4d = p4d_offset(pgd, address);
5768 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
5769 goto out;
5770
5771 pud = pud_offset(p4d, address);
5772 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
5773 goto out;
5774
5775 pmd = pmd_offset(pud, address);
5776 VM_BUG_ON(pmd_trans_huge(*pmd));
5777
5778 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
5779 if (!ptep)
5780 goto out;
5781 if (!pte_present(ptep_get(ptep)))
5782 goto unlock;
5783 *ptepp = ptep;
5784 return 0;
5785unlock:
5786 pte_unmap_unlock(ptep, *ptlp);
5787out:
5788 return -EINVAL;
5789}
5790EXPORT_SYMBOL_GPL(follow_pte);
5791
5792/**
5793 * follow_pfn - look up PFN at a user virtual address
5794 * @vma: memory mapping
5795 * @address: user virtual address
5796 * @pfn: location to store found PFN
5797 *
5798 * Only IO mappings and raw PFN mappings are allowed.
5799 *
5800 * This function does not allow the caller to read the permissions
5801 * of the PTE. Do not use it.
5802 *
5803 * Return: zero and the pfn at @pfn on success, -ve otherwise.
5804 */
5805int follow_pfn(struct vm_area_struct *vma, unsigned long address,
5806 unsigned long *pfn)
5807{
5808 int ret = -EINVAL;
5809 spinlock_t *ptl;
5810 pte_t *ptep;
5811
5812 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5813 return ret;
5814
5815 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
5816 if (ret)
5817 return ret;
5818 *pfn = pte_pfn(ptep_get(ptep));
5819 pte_unmap_unlock(ptep, ptl);
5820 return 0;
5821}
5822EXPORT_SYMBOL(follow_pfn);
5823
5824#ifdef CONFIG_HAVE_IOREMAP_PROT
5825int follow_phys(struct vm_area_struct *vma,
5826 unsigned long address, unsigned int flags,
5827 unsigned long *prot, resource_size_t *phys)
5828{
5829 int ret = -EINVAL;
5830 pte_t *ptep, pte;
5831 spinlock_t *ptl;
5832
5833 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5834 goto out;
5835
5836 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
5837 goto out;
5838 pte = ptep_get(ptep);
5839
5840 if ((flags & FOLL_WRITE) && !pte_write(pte))
5841 goto unlock;
5842
5843 *prot = pgprot_val(pte_pgprot(pte));
5844 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5845
5846 ret = 0;
5847unlock:
5848 pte_unmap_unlock(ptep, ptl);
5849out:
5850 return ret;
5851}
5852
5853/**
5854 * generic_access_phys - generic implementation for iomem mmap access
5855 * @vma: the vma to access
5856 * @addr: userspace address, not relative offset within @vma
5857 * @buf: buffer to read/write
5858 * @len: length of transfer
5859 * @write: set to FOLL_WRITE when writing, otherwise reading
5860 *
5861 * This is a generic implementation for &vm_operations_struct.access for an
5862 * iomem mapping. This callback is used by access_process_vm() when the @vma is
5863 * not page based.
5864 */
5865int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
5866 void *buf, int len, int write)
5867{
5868 resource_size_t phys_addr;
5869 unsigned long prot = 0;
5870 void __iomem *maddr;
5871 pte_t *ptep, pte;
5872 spinlock_t *ptl;
5873 int offset = offset_in_page(addr);
5874 int ret = -EINVAL;
5875
5876 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5877 return -EINVAL;
5878
5879retry:
5880 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5881 return -EINVAL;
5882 pte = ptep_get(ptep);
5883 pte_unmap_unlock(ptep, ptl);
5884
5885 prot = pgprot_val(pte_pgprot(pte));
5886 phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5887
5888 if ((write & FOLL_WRITE) && !pte_write(pte))
5889 return -EINVAL;
5890
5891 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
5892 if (!maddr)
5893 return -ENOMEM;
5894
5895 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5896 goto out_unmap;
5897
5898 if (!pte_same(pte, ptep_get(ptep))) {
5899 pte_unmap_unlock(ptep, ptl);
5900 iounmap(maddr);
5901
5902 goto retry;
5903 }
5904
5905 if (write)
5906 memcpy_toio(maddr + offset, buf, len);
5907 else
5908 memcpy_fromio(buf, maddr + offset, len);
5909 ret = len;
5910 pte_unmap_unlock(ptep, ptl);
5911out_unmap:
5912 iounmap(maddr);
5913
5914 return ret;
5915}
5916EXPORT_SYMBOL_GPL(generic_access_phys);
5917#endif
5918
5919/*
5920 * Access another process' address space as given in mm.
5921 */
5922static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
5923 void *buf, int len, unsigned int gup_flags)
5924{
5925 void *old_buf = buf;
5926 int write = gup_flags & FOLL_WRITE;
5927
5928 if (mmap_read_lock_killable(mm))
5929 return 0;
5930
5931 /* Untag the address before looking up the VMA */
5932 addr = untagged_addr_remote(mm, addr);
5933
5934 /* Avoid triggering the temporary warning in __get_user_pages */
5935 if (!vma_lookup(mm, addr) && !expand_stack(mm, addr))
5936 return 0;
5937
5938 /* ignore errors, just check how much was successfully transferred */
5939 while (len) {
5940 int bytes, offset;
5941 void *maddr;
5942 struct vm_area_struct *vma = NULL;
5943 struct page *page = get_user_page_vma_remote(mm, addr,
5944 gup_flags, &vma);
5945
5946 if (IS_ERR(page)) {
5947 /* We might need to expand the stack to access it */
5948 vma = vma_lookup(mm, addr);
5949 if (!vma) {
5950 vma = expand_stack(mm, addr);
5951
5952 /* mmap_lock was dropped on failure */
5953 if (!vma)
5954 return buf - old_buf;
5955
5956 /* Try again if stack expansion worked */
5957 continue;
5958 }
5959
5960 /*
5961 * Check if this is a VM_IO | VM_PFNMAP VMA, which
5962 * we can access using slightly different code.
5963 */
5964 bytes = 0;
5965#ifdef CONFIG_HAVE_IOREMAP_PROT
5966 if (vma->vm_ops && vma->vm_ops->access)
5967 bytes = vma->vm_ops->access(vma, addr, buf,
5968 len, write);
5969#endif
5970 if (bytes <= 0)
5971 break;
5972 } else {
5973 bytes = len;
5974 offset = addr & (PAGE_SIZE-1);
5975 if (bytes > PAGE_SIZE-offset)
5976 bytes = PAGE_SIZE-offset;
5977
5978 maddr = kmap_local_page(page);
5979 if (write) {
5980 copy_to_user_page(vma, page, addr,
5981 maddr + offset, buf, bytes);
5982 set_page_dirty_lock(page);
5983 } else {
5984 copy_from_user_page(vma, page, addr,
5985 buf, maddr + offset, bytes);
5986 }
5987 unmap_and_put_page(page, maddr);
5988 }
5989 len -= bytes;
5990 buf += bytes;
5991 addr += bytes;
5992 }
5993 mmap_read_unlock(mm);
5994
5995 return buf - old_buf;
5996}
5997
5998/**
5999 * access_remote_vm - access another process' address space
6000 * @mm: the mm_struct of the target address space
6001 * @addr: start address to access
6002 * @buf: source or destination buffer
6003 * @len: number of bytes to transfer
6004 * @gup_flags: flags modifying lookup behaviour
6005 *
6006 * The caller must hold a reference on @mm.
6007 *
6008 * Return: number of bytes copied from source to destination.
6009 */
6010int access_remote_vm(struct mm_struct *mm, unsigned long addr,
6011 void *buf, int len, unsigned int gup_flags)
6012{
6013 return __access_remote_vm(mm, addr, buf, len, gup_flags);
6014}
6015
6016/*
6017 * Access another process' address space.
6018 * Source/target buffer must be kernel space,
6019 * Do not walk the page table directly, use get_user_pages
6020 */
6021int access_process_vm(struct task_struct *tsk, unsigned long addr,
6022 void *buf, int len, unsigned int gup_flags)
6023{
6024 struct mm_struct *mm;
6025 int ret;
6026
6027 mm = get_task_mm(tsk);
6028 if (!mm)
6029 return 0;
6030
6031 ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
6032
6033 mmput(mm);
6034
6035 return ret;
6036}
6037EXPORT_SYMBOL_GPL(access_process_vm);
6038
6039/*
6040 * Print the name of a VMA.
6041 */
6042void print_vma_addr(char *prefix, unsigned long ip)
6043{
6044 struct mm_struct *mm = current->mm;
6045 struct vm_area_struct *vma;
6046
6047 /*
6048 * we might be running from an atomic context so we cannot sleep
6049 */
6050 if (!mmap_read_trylock(mm))
6051 return;
6052
6053 vma = find_vma(mm, ip);
6054 if (vma && vma->vm_file) {
6055 struct file *f = vma->vm_file;
6056 char *buf = (char *)__get_free_page(GFP_NOWAIT);
6057 if (buf) {
6058 char *p;
6059
6060 p = file_path(f, buf, PAGE_SIZE);
6061 if (IS_ERR(p))
6062 p = "?";
6063 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
6064 vma->vm_start,
6065 vma->vm_end - vma->vm_start);
6066 free_page((unsigned long)buf);
6067 }
6068 }
6069 mmap_read_unlock(mm);
6070}
6071
6072#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
6073void __might_fault(const char *file, int line)
6074{
6075 if (pagefault_disabled())
6076 return;
6077 __might_sleep(file, line);
6078#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
6079 if (current->mm)
6080 might_lock_read(¤t->mm->mmap_lock);
6081#endif
6082}
6083EXPORT_SYMBOL(__might_fault);
6084#endif
6085
6086#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
6087/*
6088 * Process all subpages of the specified huge page with the specified
6089 * operation. The target subpage will be processed last to keep its
6090 * cache lines hot.
6091 */
6092static inline int process_huge_page(
6093 unsigned long addr_hint, unsigned int pages_per_huge_page,
6094 int (*process_subpage)(unsigned long addr, int idx, void *arg),
6095 void *arg)
6096{
6097 int i, n, base, l, ret;
6098 unsigned long addr = addr_hint &
6099 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
6100
6101 /* Process target subpage last to keep its cache lines hot */
6102 might_sleep();
6103 n = (addr_hint - addr) / PAGE_SIZE;
6104 if (2 * n <= pages_per_huge_page) {
6105 /* If target subpage in first half of huge page */
6106 base = 0;
6107 l = n;
6108 /* Process subpages at the end of huge page */
6109 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
6110 cond_resched();
6111 ret = process_subpage(addr + i * PAGE_SIZE, i, arg);
6112 if (ret)
6113 return ret;
6114 }
6115 } else {
6116 /* If target subpage in second half of huge page */
6117 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
6118 l = pages_per_huge_page - n;
6119 /* Process subpages at the begin of huge page */
6120 for (i = 0; i < base; i++) {
6121 cond_resched();
6122 ret = process_subpage(addr + i * PAGE_SIZE, i, arg);
6123 if (ret)
6124 return ret;
6125 }
6126 }
6127 /*
6128 * Process remaining subpages in left-right-left-right pattern
6129 * towards the target subpage
6130 */
6131 for (i = 0; i < l; i++) {
6132 int left_idx = base + i;
6133 int right_idx = base + 2 * l - 1 - i;
6134
6135 cond_resched();
6136 ret = process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
6137 if (ret)
6138 return ret;
6139 cond_resched();
6140 ret = process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
6141 if (ret)
6142 return ret;
6143 }
6144 return 0;
6145}
6146
6147static void clear_gigantic_page(struct page *page,
6148 unsigned long addr,
6149 unsigned int pages_per_huge_page)
6150{
6151 int i;
6152 struct page *p;
6153
6154 might_sleep();
6155 for (i = 0; i < pages_per_huge_page; i++) {
6156 p = nth_page(page, i);
6157 cond_resched();
6158 clear_user_highpage(p, addr + i * PAGE_SIZE);
6159 }
6160}
6161
6162static int clear_subpage(unsigned long addr, int idx, void *arg)
6163{
6164 struct page *page = arg;
6165
6166 clear_user_highpage(page + idx, addr);
6167 return 0;
6168}
6169
6170void clear_huge_page(struct page *page,
6171 unsigned long addr_hint, unsigned int pages_per_huge_page)
6172{
6173 unsigned long addr = addr_hint &
6174 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
6175
6176 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
6177 clear_gigantic_page(page, addr, pages_per_huge_page);
6178 return;
6179 }
6180
6181 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
6182}
6183
6184static int copy_user_gigantic_page(struct folio *dst, struct folio *src,
6185 unsigned long addr,
6186 struct vm_area_struct *vma,
6187 unsigned int pages_per_huge_page)
6188{
6189 int i;
6190 struct page *dst_page;
6191 struct page *src_page;
6192
6193 for (i = 0; i < pages_per_huge_page; i++) {
6194 dst_page = folio_page(dst, i);
6195 src_page = folio_page(src, i);
6196
6197 cond_resched();
6198 if (copy_mc_user_highpage(dst_page, src_page,
6199 addr + i*PAGE_SIZE, vma)) {
6200 memory_failure_queue(page_to_pfn(src_page), 0);
6201 return -EHWPOISON;
6202 }
6203 }
6204 return 0;
6205}
6206
6207struct copy_subpage_arg {
6208 struct page *dst;
6209 struct page *src;
6210 struct vm_area_struct *vma;
6211};
6212
6213static int copy_subpage(unsigned long addr, int idx, void *arg)
6214{
6215 struct copy_subpage_arg *copy_arg = arg;
6216
6217 if (copy_mc_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
6218 addr, copy_arg->vma)) {
6219 memory_failure_queue(page_to_pfn(copy_arg->src + idx), 0);
6220 return -EHWPOISON;
6221 }
6222 return 0;
6223}
6224
6225int copy_user_large_folio(struct folio *dst, struct folio *src,
6226 unsigned long addr_hint, struct vm_area_struct *vma)
6227{
6228 unsigned int pages_per_huge_page = folio_nr_pages(dst);
6229 unsigned long addr = addr_hint &
6230 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
6231 struct copy_subpage_arg arg = {
6232 .dst = &dst->page,
6233 .src = &src->page,
6234 .vma = vma,
6235 };
6236
6237 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES))
6238 return copy_user_gigantic_page(dst, src, addr, vma,
6239 pages_per_huge_page);
6240
6241 return process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
6242}
6243
6244long copy_folio_from_user(struct folio *dst_folio,
6245 const void __user *usr_src,
6246 bool allow_pagefault)
6247{
6248 void *kaddr;
6249 unsigned long i, rc = 0;
6250 unsigned int nr_pages = folio_nr_pages(dst_folio);
6251 unsigned long ret_val = nr_pages * PAGE_SIZE;
6252 struct page *subpage;
6253
6254 for (i = 0; i < nr_pages; i++) {
6255 subpage = folio_page(dst_folio, i);
6256 kaddr = kmap_local_page(subpage);
6257 if (!allow_pagefault)
6258 pagefault_disable();
6259 rc = copy_from_user(kaddr, usr_src + i * PAGE_SIZE, PAGE_SIZE);
6260 if (!allow_pagefault)
6261 pagefault_enable();
6262 kunmap_local(kaddr);
6263
6264 ret_val -= (PAGE_SIZE - rc);
6265 if (rc)
6266 break;
6267
6268 flush_dcache_page(subpage);
6269
6270 cond_resched();
6271 }
6272 return ret_val;
6273}
6274#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
6275
6276#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
6277
6278static struct kmem_cache *page_ptl_cachep;
6279
6280void __init ptlock_cache_init(void)
6281{
6282 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
6283 SLAB_PANIC, NULL);
6284}
6285
6286bool ptlock_alloc(struct ptdesc *ptdesc)
6287{
6288 spinlock_t *ptl;
6289
6290 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
6291 if (!ptl)
6292 return false;
6293 ptdesc->ptl = ptl;
6294 return true;
6295}
6296
6297void ptlock_free(struct ptdesc *ptdesc)
6298{
6299 kmem_cache_free(page_ptl_cachep, ptdesc->ptl);
6300}
6301#endif
1/*
2 * linux/mm/memory.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
10 */
11
12/*
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
15 *
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
18 * far as I could see.
19 *
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21 */
22
23/*
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
29 */
30
31/*
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
34 *
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
37 *
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39 */
40
41#include <linux/kernel_stat.h>
42#include <linux/mm.h>
43#include <linux/hugetlb.h>
44#include <linux/mman.h>
45#include <linux/swap.h>
46#include <linux/highmem.h>
47#include <linux/pagemap.h>
48#include <linux/ksm.h>
49#include <linux/rmap.h>
50#include <linux/export.h>
51#include <linux/delayacct.h>
52#include <linux/init.h>
53#include <linux/pfn_t.h>
54#include <linux/writeback.h>
55#include <linux/memcontrol.h>
56#include <linux/mmu_notifier.h>
57#include <linux/kallsyms.h>
58#include <linux/swapops.h>
59#include <linux/elf.h>
60#include <linux/gfp.h>
61#include <linux/migrate.h>
62#include <linux/string.h>
63#include <linux/dma-debug.h>
64#include <linux/debugfs.h>
65#include <linux/userfaultfd_k.h>
66
67#include <asm/io.h>
68#include <asm/mmu_context.h>
69#include <asm/pgalloc.h>
70#include <asm/uaccess.h>
71#include <asm/tlb.h>
72#include <asm/tlbflush.h>
73#include <asm/pgtable.h>
74
75#include "internal.h"
76
77#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
78#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
79#endif
80
81#ifndef CONFIG_NEED_MULTIPLE_NODES
82/* use the per-pgdat data instead for discontigmem - mbligh */
83unsigned long max_mapnr;
84struct page *mem_map;
85
86EXPORT_SYMBOL(max_mapnr);
87EXPORT_SYMBOL(mem_map);
88#endif
89
90/*
91 * A number of key systems in x86 including ioremap() rely on the assumption
92 * that high_memory defines the upper bound on direct map memory, then end
93 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
94 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
95 * and ZONE_HIGHMEM.
96 */
97void * high_memory;
98
99EXPORT_SYMBOL(high_memory);
100
101/*
102 * Randomize the address space (stacks, mmaps, brk, etc.).
103 *
104 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
105 * as ancient (libc5 based) binaries can segfault. )
106 */
107int randomize_va_space __read_mostly =
108#ifdef CONFIG_COMPAT_BRK
109 1;
110#else
111 2;
112#endif
113
114static int __init disable_randmaps(char *s)
115{
116 randomize_va_space = 0;
117 return 1;
118}
119__setup("norandmaps", disable_randmaps);
120
121unsigned long zero_pfn __read_mostly;
122unsigned long highest_memmap_pfn __read_mostly;
123
124EXPORT_SYMBOL(zero_pfn);
125
126/*
127 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
128 */
129static int __init init_zero_pfn(void)
130{
131 zero_pfn = page_to_pfn(ZERO_PAGE(0));
132 return 0;
133}
134core_initcall(init_zero_pfn);
135
136
137#if defined(SPLIT_RSS_COUNTING)
138
139void sync_mm_rss(struct mm_struct *mm)
140{
141 int i;
142
143 for (i = 0; i < NR_MM_COUNTERS; i++) {
144 if (current->rss_stat.count[i]) {
145 add_mm_counter(mm, i, current->rss_stat.count[i]);
146 current->rss_stat.count[i] = 0;
147 }
148 }
149 current->rss_stat.events = 0;
150}
151
152static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
153{
154 struct task_struct *task = current;
155
156 if (likely(task->mm == mm))
157 task->rss_stat.count[member] += val;
158 else
159 add_mm_counter(mm, member, val);
160}
161#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
162#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
163
164/* sync counter once per 64 page faults */
165#define TASK_RSS_EVENTS_THRESH (64)
166static void check_sync_rss_stat(struct task_struct *task)
167{
168 if (unlikely(task != current))
169 return;
170 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
171 sync_mm_rss(task->mm);
172}
173#else /* SPLIT_RSS_COUNTING */
174
175#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
176#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
177
178static void check_sync_rss_stat(struct task_struct *task)
179{
180}
181
182#endif /* SPLIT_RSS_COUNTING */
183
184#ifdef HAVE_GENERIC_MMU_GATHER
185
186static bool tlb_next_batch(struct mmu_gather *tlb)
187{
188 struct mmu_gather_batch *batch;
189
190 batch = tlb->active;
191 if (batch->next) {
192 tlb->active = batch->next;
193 return true;
194 }
195
196 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
197 return false;
198
199 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
200 if (!batch)
201 return false;
202
203 tlb->batch_count++;
204 batch->next = NULL;
205 batch->nr = 0;
206 batch->max = MAX_GATHER_BATCH;
207
208 tlb->active->next = batch;
209 tlb->active = batch;
210
211 return true;
212}
213
214/* tlb_gather_mmu
215 * Called to initialize an (on-stack) mmu_gather structure for page-table
216 * tear-down from @mm. The @fullmm argument is used when @mm is without
217 * users and we're going to destroy the full address space (exit/execve).
218 */
219void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
220{
221 tlb->mm = mm;
222
223 /* Is it from 0 to ~0? */
224 tlb->fullmm = !(start | (end+1));
225 tlb->need_flush_all = 0;
226 tlb->local.next = NULL;
227 tlb->local.nr = 0;
228 tlb->local.max = ARRAY_SIZE(tlb->__pages);
229 tlb->active = &tlb->local;
230 tlb->batch_count = 0;
231
232#ifdef CONFIG_HAVE_RCU_TABLE_FREE
233 tlb->batch = NULL;
234#endif
235
236 __tlb_reset_range(tlb);
237}
238
239static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
240{
241 if (!tlb->end)
242 return;
243
244 tlb_flush(tlb);
245 mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
246#ifdef CONFIG_HAVE_RCU_TABLE_FREE
247 tlb_table_flush(tlb);
248#endif
249 __tlb_reset_range(tlb);
250}
251
252static void tlb_flush_mmu_free(struct mmu_gather *tlb)
253{
254 struct mmu_gather_batch *batch;
255
256 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
257 free_pages_and_swap_cache(batch->pages, batch->nr);
258 batch->nr = 0;
259 }
260 tlb->active = &tlb->local;
261}
262
263void tlb_flush_mmu(struct mmu_gather *tlb)
264{
265 tlb_flush_mmu_tlbonly(tlb);
266 tlb_flush_mmu_free(tlb);
267}
268
269/* tlb_finish_mmu
270 * Called at the end of the shootdown operation to free up any resources
271 * that were required.
272 */
273void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
274{
275 struct mmu_gather_batch *batch, *next;
276
277 tlb_flush_mmu(tlb);
278
279 /* keep the page table cache within bounds */
280 check_pgt_cache();
281
282 for (batch = tlb->local.next; batch; batch = next) {
283 next = batch->next;
284 free_pages((unsigned long)batch, 0);
285 }
286 tlb->local.next = NULL;
287}
288
289/* __tlb_remove_page
290 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
291 * handling the additional races in SMP caused by other CPUs caching valid
292 * mappings in their TLBs. Returns the number of free page slots left.
293 * When out of page slots we must call tlb_flush_mmu().
294 */
295int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
296{
297 struct mmu_gather_batch *batch;
298
299 VM_BUG_ON(!tlb->end);
300
301 batch = tlb->active;
302 batch->pages[batch->nr++] = page;
303 if (batch->nr == batch->max) {
304 if (!tlb_next_batch(tlb))
305 return 0;
306 batch = tlb->active;
307 }
308 VM_BUG_ON_PAGE(batch->nr > batch->max, page);
309
310 return batch->max - batch->nr;
311}
312
313#endif /* HAVE_GENERIC_MMU_GATHER */
314
315#ifdef CONFIG_HAVE_RCU_TABLE_FREE
316
317/*
318 * See the comment near struct mmu_table_batch.
319 */
320
321static void tlb_remove_table_smp_sync(void *arg)
322{
323 /* Simply deliver the interrupt */
324}
325
326static void tlb_remove_table_one(void *table)
327{
328 /*
329 * This isn't an RCU grace period and hence the page-tables cannot be
330 * assumed to be actually RCU-freed.
331 *
332 * It is however sufficient for software page-table walkers that rely on
333 * IRQ disabling. See the comment near struct mmu_table_batch.
334 */
335 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
336 __tlb_remove_table(table);
337}
338
339static void tlb_remove_table_rcu(struct rcu_head *head)
340{
341 struct mmu_table_batch *batch;
342 int i;
343
344 batch = container_of(head, struct mmu_table_batch, rcu);
345
346 for (i = 0; i < batch->nr; i++)
347 __tlb_remove_table(batch->tables[i]);
348
349 free_page((unsigned long)batch);
350}
351
352void tlb_table_flush(struct mmu_gather *tlb)
353{
354 struct mmu_table_batch **batch = &tlb->batch;
355
356 if (*batch) {
357 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
358 *batch = NULL;
359 }
360}
361
362void tlb_remove_table(struct mmu_gather *tlb, void *table)
363{
364 struct mmu_table_batch **batch = &tlb->batch;
365
366 /*
367 * When there's less then two users of this mm there cannot be a
368 * concurrent page-table walk.
369 */
370 if (atomic_read(&tlb->mm->mm_users) < 2) {
371 __tlb_remove_table(table);
372 return;
373 }
374
375 if (*batch == NULL) {
376 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
377 if (*batch == NULL) {
378 tlb_remove_table_one(table);
379 return;
380 }
381 (*batch)->nr = 0;
382 }
383 (*batch)->tables[(*batch)->nr++] = table;
384 if ((*batch)->nr == MAX_TABLE_BATCH)
385 tlb_table_flush(tlb);
386}
387
388#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
389
390/*
391 * Note: this doesn't free the actual pages themselves. That
392 * has been handled earlier when unmapping all the memory regions.
393 */
394static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
395 unsigned long addr)
396{
397 pgtable_t token = pmd_pgtable(*pmd);
398 pmd_clear(pmd);
399 pte_free_tlb(tlb, token, addr);
400 atomic_long_dec(&tlb->mm->nr_ptes);
401}
402
403static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
404 unsigned long addr, unsigned long end,
405 unsigned long floor, unsigned long ceiling)
406{
407 pmd_t *pmd;
408 unsigned long next;
409 unsigned long start;
410
411 start = addr;
412 pmd = pmd_offset(pud, addr);
413 do {
414 next = pmd_addr_end(addr, end);
415 if (pmd_none_or_clear_bad(pmd))
416 continue;
417 free_pte_range(tlb, pmd, addr);
418 } while (pmd++, addr = next, addr != end);
419
420 start &= PUD_MASK;
421 if (start < floor)
422 return;
423 if (ceiling) {
424 ceiling &= PUD_MASK;
425 if (!ceiling)
426 return;
427 }
428 if (end - 1 > ceiling - 1)
429 return;
430
431 pmd = pmd_offset(pud, start);
432 pud_clear(pud);
433 pmd_free_tlb(tlb, pmd, start);
434 mm_dec_nr_pmds(tlb->mm);
435}
436
437static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
438 unsigned long addr, unsigned long end,
439 unsigned long floor, unsigned long ceiling)
440{
441 pud_t *pud;
442 unsigned long next;
443 unsigned long start;
444
445 start = addr;
446 pud = pud_offset(pgd, addr);
447 do {
448 next = pud_addr_end(addr, end);
449 if (pud_none_or_clear_bad(pud))
450 continue;
451 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
452 } while (pud++, addr = next, addr != end);
453
454 start &= PGDIR_MASK;
455 if (start < floor)
456 return;
457 if (ceiling) {
458 ceiling &= PGDIR_MASK;
459 if (!ceiling)
460 return;
461 }
462 if (end - 1 > ceiling - 1)
463 return;
464
465 pud = pud_offset(pgd, start);
466 pgd_clear(pgd);
467 pud_free_tlb(tlb, pud, start);
468}
469
470/*
471 * This function frees user-level page tables of a process.
472 */
473void free_pgd_range(struct mmu_gather *tlb,
474 unsigned long addr, unsigned long end,
475 unsigned long floor, unsigned long ceiling)
476{
477 pgd_t *pgd;
478 unsigned long next;
479
480 /*
481 * The next few lines have given us lots of grief...
482 *
483 * Why are we testing PMD* at this top level? Because often
484 * there will be no work to do at all, and we'd prefer not to
485 * go all the way down to the bottom just to discover that.
486 *
487 * Why all these "- 1"s? Because 0 represents both the bottom
488 * of the address space and the top of it (using -1 for the
489 * top wouldn't help much: the masks would do the wrong thing).
490 * The rule is that addr 0 and floor 0 refer to the bottom of
491 * the address space, but end 0 and ceiling 0 refer to the top
492 * Comparisons need to use "end - 1" and "ceiling - 1" (though
493 * that end 0 case should be mythical).
494 *
495 * Wherever addr is brought up or ceiling brought down, we must
496 * be careful to reject "the opposite 0" before it confuses the
497 * subsequent tests. But what about where end is brought down
498 * by PMD_SIZE below? no, end can't go down to 0 there.
499 *
500 * Whereas we round start (addr) and ceiling down, by different
501 * masks at different levels, in order to test whether a table
502 * now has no other vmas using it, so can be freed, we don't
503 * bother to round floor or end up - the tests don't need that.
504 */
505
506 addr &= PMD_MASK;
507 if (addr < floor) {
508 addr += PMD_SIZE;
509 if (!addr)
510 return;
511 }
512 if (ceiling) {
513 ceiling &= PMD_MASK;
514 if (!ceiling)
515 return;
516 }
517 if (end - 1 > ceiling - 1)
518 end -= PMD_SIZE;
519 if (addr > end - 1)
520 return;
521
522 pgd = pgd_offset(tlb->mm, addr);
523 do {
524 next = pgd_addr_end(addr, end);
525 if (pgd_none_or_clear_bad(pgd))
526 continue;
527 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
528 } while (pgd++, addr = next, addr != end);
529}
530
531void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
532 unsigned long floor, unsigned long ceiling)
533{
534 while (vma) {
535 struct vm_area_struct *next = vma->vm_next;
536 unsigned long addr = vma->vm_start;
537
538 /*
539 * Hide vma from rmap and truncate_pagecache before freeing
540 * pgtables
541 */
542 unlink_anon_vmas(vma);
543 unlink_file_vma(vma);
544
545 if (is_vm_hugetlb_page(vma)) {
546 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
547 floor, next? next->vm_start: ceiling);
548 } else {
549 /*
550 * Optimization: gather nearby vmas into one call down
551 */
552 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
553 && !is_vm_hugetlb_page(next)) {
554 vma = next;
555 next = vma->vm_next;
556 unlink_anon_vmas(vma);
557 unlink_file_vma(vma);
558 }
559 free_pgd_range(tlb, addr, vma->vm_end,
560 floor, next? next->vm_start: ceiling);
561 }
562 vma = next;
563 }
564}
565
566int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
567{
568 spinlock_t *ptl;
569 pgtable_t new = pte_alloc_one(mm, address);
570 if (!new)
571 return -ENOMEM;
572
573 /*
574 * Ensure all pte setup (eg. pte page lock and page clearing) are
575 * visible before the pte is made visible to other CPUs by being
576 * put into page tables.
577 *
578 * The other side of the story is the pointer chasing in the page
579 * table walking code (when walking the page table without locking;
580 * ie. most of the time). Fortunately, these data accesses consist
581 * of a chain of data-dependent loads, meaning most CPUs (alpha
582 * being the notable exception) will already guarantee loads are
583 * seen in-order. See the alpha page table accessors for the
584 * smp_read_barrier_depends() barriers in page table walking code.
585 */
586 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
587
588 ptl = pmd_lock(mm, pmd);
589 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
590 atomic_long_inc(&mm->nr_ptes);
591 pmd_populate(mm, pmd, new);
592 new = NULL;
593 }
594 spin_unlock(ptl);
595 if (new)
596 pte_free(mm, new);
597 return 0;
598}
599
600int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
601{
602 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
603 if (!new)
604 return -ENOMEM;
605
606 smp_wmb(); /* See comment in __pte_alloc */
607
608 spin_lock(&init_mm.page_table_lock);
609 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
610 pmd_populate_kernel(&init_mm, pmd, new);
611 new = NULL;
612 }
613 spin_unlock(&init_mm.page_table_lock);
614 if (new)
615 pte_free_kernel(&init_mm, new);
616 return 0;
617}
618
619static inline void init_rss_vec(int *rss)
620{
621 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
622}
623
624static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
625{
626 int i;
627
628 if (current->mm == mm)
629 sync_mm_rss(mm);
630 for (i = 0; i < NR_MM_COUNTERS; i++)
631 if (rss[i])
632 add_mm_counter(mm, i, rss[i]);
633}
634
635/*
636 * This function is called to print an error when a bad pte
637 * is found. For example, we might have a PFN-mapped pte in
638 * a region that doesn't allow it.
639 *
640 * The calling function must still handle the error.
641 */
642static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
643 pte_t pte, struct page *page)
644{
645 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
646 pud_t *pud = pud_offset(pgd, addr);
647 pmd_t *pmd = pmd_offset(pud, addr);
648 struct address_space *mapping;
649 pgoff_t index;
650 static unsigned long resume;
651 static unsigned long nr_shown;
652 static unsigned long nr_unshown;
653
654 /*
655 * Allow a burst of 60 reports, then keep quiet for that minute;
656 * or allow a steady drip of one report per second.
657 */
658 if (nr_shown == 60) {
659 if (time_before(jiffies, resume)) {
660 nr_unshown++;
661 return;
662 }
663 if (nr_unshown) {
664 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
665 nr_unshown);
666 nr_unshown = 0;
667 }
668 nr_shown = 0;
669 }
670 if (nr_shown++ == 0)
671 resume = jiffies + 60 * HZ;
672
673 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
674 index = linear_page_index(vma, addr);
675
676 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
677 current->comm,
678 (long long)pte_val(pte), (long long)pmd_val(*pmd));
679 if (page)
680 dump_page(page, "bad pte");
681 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
682 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
683 /*
684 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
685 */
686 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
687 vma->vm_file,
688 vma->vm_ops ? vma->vm_ops->fault : NULL,
689 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
690 mapping ? mapping->a_ops->readpage : NULL);
691 dump_stack();
692 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
693}
694
695/*
696 * vm_normal_page -- This function gets the "struct page" associated with a pte.
697 *
698 * "Special" mappings do not wish to be associated with a "struct page" (either
699 * it doesn't exist, or it exists but they don't want to touch it). In this
700 * case, NULL is returned here. "Normal" mappings do have a struct page.
701 *
702 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
703 * pte bit, in which case this function is trivial. Secondly, an architecture
704 * may not have a spare pte bit, which requires a more complicated scheme,
705 * described below.
706 *
707 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
708 * special mapping (even if there are underlying and valid "struct pages").
709 * COWed pages of a VM_PFNMAP are always normal.
710 *
711 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
712 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
713 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
714 * mapping will always honor the rule
715 *
716 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
717 *
718 * And for normal mappings this is false.
719 *
720 * This restricts such mappings to be a linear translation from virtual address
721 * to pfn. To get around this restriction, we allow arbitrary mappings so long
722 * as the vma is not a COW mapping; in that case, we know that all ptes are
723 * special (because none can have been COWed).
724 *
725 *
726 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
727 *
728 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
729 * page" backing, however the difference is that _all_ pages with a struct
730 * page (that is, those where pfn_valid is true) are refcounted and considered
731 * normal pages by the VM. The disadvantage is that pages are refcounted
732 * (which can be slower and simply not an option for some PFNMAP users). The
733 * advantage is that we don't have to follow the strict linearity rule of
734 * PFNMAP mappings in order to support COWable mappings.
735 *
736 */
737#ifdef __HAVE_ARCH_PTE_SPECIAL
738# define HAVE_PTE_SPECIAL 1
739#else
740# define HAVE_PTE_SPECIAL 0
741#endif
742struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
743 pte_t pte)
744{
745 unsigned long pfn = pte_pfn(pte);
746
747 if (HAVE_PTE_SPECIAL) {
748 if (likely(!pte_special(pte)))
749 goto check_pfn;
750 if (vma->vm_ops && vma->vm_ops->find_special_page)
751 return vma->vm_ops->find_special_page(vma, addr);
752 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
753 return NULL;
754 if (!is_zero_pfn(pfn))
755 print_bad_pte(vma, addr, pte, NULL);
756 return NULL;
757 }
758
759 /* !HAVE_PTE_SPECIAL case follows: */
760
761 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
762 if (vma->vm_flags & VM_MIXEDMAP) {
763 if (!pfn_valid(pfn))
764 return NULL;
765 goto out;
766 } else {
767 unsigned long off;
768 off = (addr - vma->vm_start) >> PAGE_SHIFT;
769 if (pfn == vma->vm_pgoff + off)
770 return NULL;
771 if (!is_cow_mapping(vma->vm_flags))
772 return NULL;
773 }
774 }
775
776 if (is_zero_pfn(pfn))
777 return NULL;
778check_pfn:
779 if (unlikely(pfn > highest_memmap_pfn)) {
780 print_bad_pte(vma, addr, pte, NULL);
781 return NULL;
782 }
783
784 /*
785 * NOTE! We still have PageReserved() pages in the page tables.
786 * eg. VDSO mappings can cause them to exist.
787 */
788out:
789 return pfn_to_page(pfn);
790}
791
792#ifdef CONFIG_TRANSPARENT_HUGEPAGE
793struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
794 pmd_t pmd)
795{
796 unsigned long pfn = pmd_pfn(pmd);
797
798 /*
799 * There is no pmd_special() but there may be special pmds, e.g.
800 * in a direct-access (dax) mapping, so let's just replicate the
801 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
802 */
803 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
804 if (vma->vm_flags & VM_MIXEDMAP) {
805 if (!pfn_valid(pfn))
806 return NULL;
807 goto out;
808 } else {
809 unsigned long off;
810 off = (addr - vma->vm_start) >> PAGE_SHIFT;
811 if (pfn == vma->vm_pgoff + off)
812 return NULL;
813 if (!is_cow_mapping(vma->vm_flags))
814 return NULL;
815 }
816 }
817
818 if (is_zero_pfn(pfn))
819 return NULL;
820 if (unlikely(pfn > highest_memmap_pfn))
821 return NULL;
822
823 /*
824 * NOTE! We still have PageReserved() pages in the page tables.
825 * eg. VDSO mappings can cause them to exist.
826 */
827out:
828 return pfn_to_page(pfn);
829}
830#endif
831
832/*
833 * copy one vm_area from one task to the other. Assumes the page tables
834 * already present in the new task to be cleared in the whole range
835 * covered by this vma.
836 */
837
838static inline unsigned long
839copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
840 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
841 unsigned long addr, int *rss)
842{
843 unsigned long vm_flags = vma->vm_flags;
844 pte_t pte = *src_pte;
845 struct page *page;
846
847 /* pte contains position in swap or file, so copy. */
848 if (unlikely(!pte_present(pte))) {
849 swp_entry_t entry = pte_to_swp_entry(pte);
850
851 if (likely(!non_swap_entry(entry))) {
852 if (swap_duplicate(entry) < 0)
853 return entry.val;
854
855 /* make sure dst_mm is on swapoff's mmlist. */
856 if (unlikely(list_empty(&dst_mm->mmlist))) {
857 spin_lock(&mmlist_lock);
858 if (list_empty(&dst_mm->mmlist))
859 list_add(&dst_mm->mmlist,
860 &src_mm->mmlist);
861 spin_unlock(&mmlist_lock);
862 }
863 rss[MM_SWAPENTS]++;
864 } else if (is_migration_entry(entry)) {
865 page = migration_entry_to_page(entry);
866
867 rss[mm_counter(page)]++;
868
869 if (is_write_migration_entry(entry) &&
870 is_cow_mapping(vm_flags)) {
871 /*
872 * COW mappings require pages in both
873 * parent and child to be set to read.
874 */
875 make_migration_entry_read(&entry);
876 pte = swp_entry_to_pte(entry);
877 if (pte_swp_soft_dirty(*src_pte))
878 pte = pte_swp_mksoft_dirty(pte);
879 set_pte_at(src_mm, addr, src_pte, pte);
880 }
881 }
882 goto out_set_pte;
883 }
884
885 /*
886 * If it's a COW mapping, write protect it both
887 * in the parent and the child
888 */
889 if (is_cow_mapping(vm_flags)) {
890 ptep_set_wrprotect(src_mm, addr, src_pte);
891 pte = pte_wrprotect(pte);
892 }
893
894 /*
895 * If it's a shared mapping, mark it clean in
896 * the child
897 */
898 if (vm_flags & VM_SHARED)
899 pte = pte_mkclean(pte);
900 pte = pte_mkold(pte);
901
902 page = vm_normal_page(vma, addr, pte);
903 if (page) {
904 get_page(page);
905 page_dup_rmap(page, false);
906 rss[mm_counter(page)]++;
907 }
908
909out_set_pte:
910 set_pte_at(dst_mm, addr, dst_pte, pte);
911 return 0;
912}
913
914static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
915 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
916 unsigned long addr, unsigned long end)
917{
918 pte_t *orig_src_pte, *orig_dst_pte;
919 pte_t *src_pte, *dst_pte;
920 spinlock_t *src_ptl, *dst_ptl;
921 int progress = 0;
922 int rss[NR_MM_COUNTERS];
923 swp_entry_t entry = (swp_entry_t){0};
924
925again:
926 init_rss_vec(rss);
927
928 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
929 if (!dst_pte)
930 return -ENOMEM;
931 src_pte = pte_offset_map(src_pmd, addr);
932 src_ptl = pte_lockptr(src_mm, src_pmd);
933 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
934 orig_src_pte = src_pte;
935 orig_dst_pte = dst_pte;
936 arch_enter_lazy_mmu_mode();
937
938 do {
939 /*
940 * We are holding two locks at this point - either of them
941 * could generate latencies in another task on another CPU.
942 */
943 if (progress >= 32) {
944 progress = 0;
945 if (need_resched() ||
946 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
947 break;
948 }
949 if (pte_none(*src_pte)) {
950 progress++;
951 continue;
952 }
953 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
954 vma, addr, rss);
955 if (entry.val)
956 break;
957 progress += 8;
958 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
959
960 arch_leave_lazy_mmu_mode();
961 spin_unlock(src_ptl);
962 pte_unmap(orig_src_pte);
963 add_mm_rss_vec(dst_mm, rss);
964 pte_unmap_unlock(orig_dst_pte, dst_ptl);
965 cond_resched();
966
967 if (entry.val) {
968 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
969 return -ENOMEM;
970 progress = 0;
971 }
972 if (addr != end)
973 goto again;
974 return 0;
975}
976
977static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
978 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
979 unsigned long addr, unsigned long end)
980{
981 pmd_t *src_pmd, *dst_pmd;
982 unsigned long next;
983
984 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
985 if (!dst_pmd)
986 return -ENOMEM;
987 src_pmd = pmd_offset(src_pud, addr);
988 do {
989 next = pmd_addr_end(addr, end);
990 if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
991 int err;
992 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
993 err = copy_huge_pmd(dst_mm, src_mm,
994 dst_pmd, src_pmd, addr, vma);
995 if (err == -ENOMEM)
996 return -ENOMEM;
997 if (!err)
998 continue;
999 /* fall through */
1000 }
1001 if (pmd_none_or_clear_bad(src_pmd))
1002 continue;
1003 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1004 vma, addr, next))
1005 return -ENOMEM;
1006 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1007 return 0;
1008}
1009
1010static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1011 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1012 unsigned long addr, unsigned long end)
1013{
1014 pud_t *src_pud, *dst_pud;
1015 unsigned long next;
1016
1017 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1018 if (!dst_pud)
1019 return -ENOMEM;
1020 src_pud = pud_offset(src_pgd, addr);
1021 do {
1022 next = pud_addr_end(addr, end);
1023 if (pud_none_or_clear_bad(src_pud))
1024 continue;
1025 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1026 vma, addr, next))
1027 return -ENOMEM;
1028 } while (dst_pud++, src_pud++, addr = next, addr != end);
1029 return 0;
1030}
1031
1032int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1033 struct vm_area_struct *vma)
1034{
1035 pgd_t *src_pgd, *dst_pgd;
1036 unsigned long next;
1037 unsigned long addr = vma->vm_start;
1038 unsigned long end = vma->vm_end;
1039 unsigned long mmun_start; /* For mmu_notifiers */
1040 unsigned long mmun_end; /* For mmu_notifiers */
1041 bool is_cow;
1042 int ret;
1043
1044 /*
1045 * Don't copy ptes where a page fault will fill them correctly.
1046 * Fork becomes much lighter when there are big shared or private
1047 * readonly mappings. The tradeoff is that copy_page_range is more
1048 * efficient than faulting.
1049 */
1050 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1051 !vma->anon_vma)
1052 return 0;
1053
1054 if (is_vm_hugetlb_page(vma))
1055 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1056
1057 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1058 /*
1059 * We do not free on error cases below as remove_vma
1060 * gets called on error from higher level routine
1061 */
1062 ret = track_pfn_copy(vma);
1063 if (ret)
1064 return ret;
1065 }
1066
1067 /*
1068 * We need to invalidate the secondary MMU mappings only when
1069 * there could be a permission downgrade on the ptes of the
1070 * parent mm. And a permission downgrade will only happen if
1071 * is_cow_mapping() returns true.
1072 */
1073 is_cow = is_cow_mapping(vma->vm_flags);
1074 mmun_start = addr;
1075 mmun_end = end;
1076 if (is_cow)
1077 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1078 mmun_end);
1079
1080 ret = 0;
1081 dst_pgd = pgd_offset(dst_mm, addr);
1082 src_pgd = pgd_offset(src_mm, addr);
1083 do {
1084 next = pgd_addr_end(addr, end);
1085 if (pgd_none_or_clear_bad(src_pgd))
1086 continue;
1087 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1088 vma, addr, next))) {
1089 ret = -ENOMEM;
1090 break;
1091 }
1092 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1093
1094 if (is_cow)
1095 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1096 return ret;
1097}
1098
1099static unsigned long zap_pte_range(struct mmu_gather *tlb,
1100 struct vm_area_struct *vma, pmd_t *pmd,
1101 unsigned long addr, unsigned long end,
1102 struct zap_details *details)
1103{
1104 struct mm_struct *mm = tlb->mm;
1105 int force_flush = 0;
1106 int rss[NR_MM_COUNTERS];
1107 spinlock_t *ptl;
1108 pte_t *start_pte;
1109 pte_t *pte;
1110 swp_entry_t entry;
1111
1112again:
1113 init_rss_vec(rss);
1114 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1115 pte = start_pte;
1116 arch_enter_lazy_mmu_mode();
1117 do {
1118 pte_t ptent = *pte;
1119 if (pte_none(ptent)) {
1120 continue;
1121 }
1122
1123 if (pte_present(ptent)) {
1124 struct page *page;
1125
1126 page = vm_normal_page(vma, addr, ptent);
1127 if (unlikely(details) && page) {
1128 /*
1129 * unmap_shared_mapping_pages() wants to
1130 * invalidate cache without truncating:
1131 * unmap shared but keep private pages.
1132 */
1133 if (details->check_mapping &&
1134 details->check_mapping != page->mapping)
1135 continue;
1136 }
1137 ptent = ptep_get_and_clear_full(mm, addr, pte,
1138 tlb->fullmm);
1139 tlb_remove_tlb_entry(tlb, pte, addr);
1140 if (unlikely(!page))
1141 continue;
1142
1143 if (!PageAnon(page)) {
1144 if (pte_dirty(ptent)) {
1145 /*
1146 * oom_reaper cannot tear down dirty
1147 * pages
1148 */
1149 if (unlikely(details && details->ignore_dirty))
1150 continue;
1151 force_flush = 1;
1152 set_page_dirty(page);
1153 }
1154 if (pte_young(ptent) &&
1155 likely(!(vma->vm_flags & VM_SEQ_READ)))
1156 mark_page_accessed(page);
1157 }
1158 rss[mm_counter(page)]--;
1159 page_remove_rmap(page, false);
1160 if (unlikely(page_mapcount(page) < 0))
1161 print_bad_pte(vma, addr, ptent, page);
1162 if (unlikely(!__tlb_remove_page(tlb, page))) {
1163 force_flush = 1;
1164 addr += PAGE_SIZE;
1165 break;
1166 }
1167 continue;
1168 }
1169 /* only check swap_entries if explicitly asked for in details */
1170 if (unlikely(details && !details->check_swap_entries))
1171 continue;
1172
1173 entry = pte_to_swp_entry(ptent);
1174 if (!non_swap_entry(entry))
1175 rss[MM_SWAPENTS]--;
1176 else if (is_migration_entry(entry)) {
1177 struct page *page;
1178
1179 page = migration_entry_to_page(entry);
1180 rss[mm_counter(page)]--;
1181 }
1182 if (unlikely(!free_swap_and_cache(entry)))
1183 print_bad_pte(vma, addr, ptent, NULL);
1184 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1185 } while (pte++, addr += PAGE_SIZE, addr != end);
1186
1187 add_mm_rss_vec(mm, rss);
1188 arch_leave_lazy_mmu_mode();
1189
1190 /* Do the actual TLB flush before dropping ptl */
1191 if (force_flush)
1192 tlb_flush_mmu_tlbonly(tlb);
1193 pte_unmap_unlock(start_pte, ptl);
1194
1195 /*
1196 * If we forced a TLB flush (either due to running out of
1197 * batch buffers or because we needed to flush dirty TLB
1198 * entries before releasing the ptl), free the batched
1199 * memory too. Restart if we didn't do everything.
1200 */
1201 if (force_flush) {
1202 force_flush = 0;
1203 tlb_flush_mmu_free(tlb);
1204
1205 if (addr != end)
1206 goto again;
1207 }
1208
1209 return addr;
1210}
1211
1212static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1213 struct vm_area_struct *vma, pud_t *pud,
1214 unsigned long addr, unsigned long end,
1215 struct zap_details *details)
1216{
1217 pmd_t *pmd;
1218 unsigned long next;
1219
1220 pmd = pmd_offset(pud, addr);
1221 do {
1222 next = pmd_addr_end(addr, end);
1223 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1224 if (next - addr != HPAGE_PMD_SIZE) {
1225 VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1226 !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1227 split_huge_pmd(vma, pmd, addr);
1228 } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1229 goto next;
1230 /* fall through */
1231 }
1232 /*
1233 * Here there can be other concurrent MADV_DONTNEED or
1234 * trans huge page faults running, and if the pmd is
1235 * none or trans huge it can change under us. This is
1236 * because MADV_DONTNEED holds the mmap_sem in read
1237 * mode.
1238 */
1239 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1240 goto next;
1241 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1242next:
1243 cond_resched();
1244 } while (pmd++, addr = next, addr != end);
1245
1246 return addr;
1247}
1248
1249static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1250 struct vm_area_struct *vma, pgd_t *pgd,
1251 unsigned long addr, unsigned long end,
1252 struct zap_details *details)
1253{
1254 pud_t *pud;
1255 unsigned long next;
1256
1257 pud = pud_offset(pgd, addr);
1258 do {
1259 next = pud_addr_end(addr, end);
1260 if (pud_none_or_clear_bad(pud))
1261 continue;
1262 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1263 } while (pud++, addr = next, addr != end);
1264
1265 return addr;
1266}
1267
1268void unmap_page_range(struct mmu_gather *tlb,
1269 struct vm_area_struct *vma,
1270 unsigned long addr, unsigned long end,
1271 struct zap_details *details)
1272{
1273 pgd_t *pgd;
1274 unsigned long next;
1275
1276 BUG_ON(addr >= end);
1277 tlb_start_vma(tlb, vma);
1278 pgd = pgd_offset(vma->vm_mm, addr);
1279 do {
1280 next = pgd_addr_end(addr, end);
1281 if (pgd_none_or_clear_bad(pgd))
1282 continue;
1283 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1284 } while (pgd++, addr = next, addr != end);
1285 tlb_end_vma(tlb, vma);
1286}
1287
1288
1289static void unmap_single_vma(struct mmu_gather *tlb,
1290 struct vm_area_struct *vma, unsigned long start_addr,
1291 unsigned long end_addr,
1292 struct zap_details *details)
1293{
1294 unsigned long start = max(vma->vm_start, start_addr);
1295 unsigned long end;
1296
1297 if (start >= vma->vm_end)
1298 return;
1299 end = min(vma->vm_end, end_addr);
1300 if (end <= vma->vm_start)
1301 return;
1302
1303 if (vma->vm_file)
1304 uprobe_munmap(vma, start, end);
1305
1306 if (unlikely(vma->vm_flags & VM_PFNMAP))
1307 untrack_pfn(vma, 0, 0);
1308
1309 if (start != end) {
1310 if (unlikely(is_vm_hugetlb_page(vma))) {
1311 /*
1312 * It is undesirable to test vma->vm_file as it
1313 * should be non-null for valid hugetlb area.
1314 * However, vm_file will be NULL in the error
1315 * cleanup path of mmap_region. When
1316 * hugetlbfs ->mmap method fails,
1317 * mmap_region() nullifies vma->vm_file
1318 * before calling this function to clean up.
1319 * Since no pte has actually been setup, it is
1320 * safe to do nothing in this case.
1321 */
1322 if (vma->vm_file) {
1323 i_mmap_lock_write(vma->vm_file->f_mapping);
1324 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1325 i_mmap_unlock_write(vma->vm_file->f_mapping);
1326 }
1327 } else
1328 unmap_page_range(tlb, vma, start, end, details);
1329 }
1330}
1331
1332/**
1333 * unmap_vmas - unmap a range of memory covered by a list of vma's
1334 * @tlb: address of the caller's struct mmu_gather
1335 * @vma: the starting vma
1336 * @start_addr: virtual address at which to start unmapping
1337 * @end_addr: virtual address at which to end unmapping
1338 *
1339 * Unmap all pages in the vma list.
1340 *
1341 * Only addresses between `start' and `end' will be unmapped.
1342 *
1343 * The VMA list must be sorted in ascending virtual address order.
1344 *
1345 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1346 * range after unmap_vmas() returns. So the only responsibility here is to
1347 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1348 * drops the lock and schedules.
1349 */
1350void unmap_vmas(struct mmu_gather *tlb,
1351 struct vm_area_struct *vma, unsigned long start_addr,
1352 unsigned long end_addr)
1353{
1354 struct mm_struct *mm = vma->vm_mm;
1355
1356 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1357 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1358 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1359 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1360}
1361
1362/**
1363 * zap_page_range - remove user pages in a given range
1364 * @vma: vm_area_struct holding the applicable pages
1365 * @start: starting address of pages to zap
1366 * @size: number of bytes to zap
1367 * @details: details of shared cache invalidation
1368 *
1369 * Caller must protect the VMA list
1370 */
1371void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1372 unsigned long size, struct zap_details *details)
1373{
1374 struct mm_struct *mm = vma->vm_mm;
1375 struct mmu_gather tlb;
1376 unsigned long end = start + size;
1377
1378 lru_add_drain();
1379 tlb_gather_mmu(&tlb, mm, start, end);
1380 update_hiwater_rss(mm);
1381 mmu_notifier_invalidate_range_start(mm, start, end);
1382 for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1383 unmap_single_vma(&tlb, vma, start, end, details);
1384 mmu_notifier_invalidate_range_end(mm, start, end);
1385 tlb_finish_mmu(&tlb, start, end);
1386}
1387
1388/**
1389 * zap_page_range_single - remove user pages in a given range
1390 * @vma: vm_area_struct holding the applicable pages
1391 * @address: starting address of pages to zap
1392 * @size: number of bytes to zap
1393 * @details: details of shared cache invalidation
1394 *
1395 * The range must fit into one VMA.
1396 */
1397static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1398 unsigned long size, struct zap_details *details)
1399{
1400 struct mm_struct *mm = vma->vm_mm;
1401 struct mmu_gather tlb;
1402 unsigned long end = address + size;
1403
1404 lru_add_drain();
1405 tlb_gather_mmu(&tlb, mm, address, end);
1406 update_hiwater_rss(mm);
1407 mmu_notifier_invalidate_range_start(mm, address, end);
1408 unmap_single_vma(&tlb, vma, address, end, details);
1409 mmu_notifier_invalidate_range_end(mm, address, end);
1410 tlb_finish_mmu(&tlb, address, end);
1411}
1412
1413/**
1414 * zap_vma_ptes - remove ptes mapping the vma
1415 * @vma: vm_area_struct holding ptes to be zapped
1416 * @address: starting address of pages to zap
1417 * @size: number of bytes to zap
1418 *
1419 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1420 *
1421 * The entire address range must be fully contained within the vma.
1422 *
1423 * Returns 0 if successful.
1424 */
1425int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1426 unsigned long size)
1427{
1428 if (address < vma->vm_start || address + size > vma->vm_end ||
1429 !(vma->vm_flags & VM_PFNMAP))
1430 return -1;
1431 zap_page_range_single(vma, address, size, NULL);
1432 return 0;
1433}
1434EXPORT_SYMBOL_GPL(zap_vma_ptes);
1435
1436pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1437 spinlock_t **ptl)
1438{
1439 pgd_t * pgd = pgd_offset(mm, addr);
1440 pud_t * pud = pud_alloc(mm, pgd, addr);
1441 if (pud) {
1442 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1443 if (pmd) {
1444 VM_BUG_ON(pmd_trans_huge(*pmd));
1445 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1446 }
1447 }
1448 return NULL;
1449}
1450
1451/*
1452 * This is the old fallback for page remapping.
1453 *
1454 * For historical reasons, it only allows reserved pages. Only
1455 * old drivers should use this, and they needed to mark their
1456 * pages reserved for the old functions anyway.
1457 */
1458static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1459 struct page *page, pgprot_t prot)
1460{
1461 struct mm_struct *mm = vma->vm_mm;
1462 int retval;
1463 pte_t *pte;
1464 spinlock_t *ptl;
1465
1466 retval = -EINVAL;
1467 if (PageAnon(page))
1468 goto out;
1469 retval = -ENOMEM;
1470 flush_dcache_page(page);
1471 pte = get_locked_pte(mm, addr, &ptl);
1472 if (!pte)
1473 goto out;
1474 retval = -EBUSY;
1475 if (!pte_none(*pte))
1476 goto out_unlock;
1477
1478 /* Ok, finally just insert the thing.. */
1479 get_page(page);
1480 inc_mm_counter_fast(mm, mm_counter_file(page));
1481 page_add_file_rmap(page);
1482 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1483
1484 retval = 0;
1485 pte_unmap_unlock(pte, ptl);
1486 return retval;
1487out_unlock:
1488 pte_unmap_unlock(pte, ptl);
1489out:
1490 return retval;
1491}
1492
1493/**
1494 * vm_insert_page - insert single page into user vma
1495 * @vma: user vma to map to
1496 * @addr: target user address of this page
1497 * @page: source kernel page
1498 *
1499 * This allows drivers to insert individual pages they've allocated
1500 * into a user vma.
1501 *
1502 * The page has to be a nice clean _individual_ kernel allocation.
1503 * If you allocate a compound page, you need to have marked it as
1504 * such (__GFP_COMP), or manually just split the page up yourself
1505 * (see split_page()).
1506 *
1507 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1508 * took an arbitrary page protection parameter. This doesn't allow
1509 * that. Your vma protection will have to be set up correctly, which
1510 * means that if you want a shared writable mapping, you'd better
1511 * ask for a shared writable mapping!
1512 *
1513 * The page does not need to be reserved.
1514 *
1515 * Usually this function is called from f_op->mmap() handler
1516 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1517 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1518 * function from other places, for example from page-fault handler.
1519 */
1520int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1521 struct page *page)
1522{
1523 if (addr < vma->vm_start || addr >= vma->vm_end)
1524 return -EFAULT;
1525 if (!page_count(page))
1526 return -EINVAL;
1527 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1528 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1529 BUG_ON(vma->vm_flags & VM_PFNMAP);
1530 vma->vm_flags |= VM_MIXEDMAP;
1531 }
1532 return insert_page(vma, addr, page, vma->vm_page_prot);
1533}
1534EXPORT_SYMBOL(vm_insert_page);
1535
1536static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1537 pfn_t pfn, pgprot_t prot)
1538{
1539 struct mm_struct *mm = vma->vm_mm;
1540 int retval;
1541 pte_t *pte, entry;
1542 spinlock_t *ptl;
1543
1544 retval = -ENOMEM;
1545 pte = get_locked_pte(mm, addr, &ptl);
1546 if (!pte)
1547 goto out;
1548 retval = -EBUSY;
1549 if (!pte_none(*pte))
1550 goto out_unlock;
1551
1552 /* Ok, finally just insert the thing.. */
1553 if (pfn_t_devmap(pfn))
1554 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1555 else
1556 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1557 set_pte_at(mm, addr, pte, entry);
1558 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1559
1560 retval = 0;
1561out_unlock:
1562 pte_unmap_unlock(pte, ptl);
1563out:
1564 return retval;
1565}
1566
1567/**
1568 * vm_insert_pfn - insert single pfn into user vma
1569 * @vma: user vma to map to
1570 * @addr: target user address of this page
1571 * @pfn: source kernel pfn
1572 *
1573 * Similar to vm_insert_page, this allows drivers to insert individual pages
1574 * they've allocated into a user vma. Same comments apply.
1575 *
1576 * This function should only be called from a vm_ops->fault handler, and
1577 * in that case the handler should return NULL.
1578 *
1579 * vma cannot be a COW mapping.
1580 *
1581 * As this is called only for pages that do not currently exist, we
1582 * do not need to flush old virtual caches or the TLB.
1583 */
1584int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1585 unsigned long pfn)
1586{
1587 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1588}
1589EXPORT_SYMBOL(vm_insert_pfn);
1590
1591/**
1592 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1593 * @vma: user vma to map to
1594 * @addr: target user address of this page
1595 * @pfn: source kernel pfn
1596 * @pgprot: pgprot flags for the inserted page
1597 *
1598 * This is exactly like vm_insert_pfn, except that it allows drivers to
1599 * to override pgprot on a per-page basis.
1600 *
1601 * This only makes sense for IO mappings, and it makes no sense for
1602 * cow mappings. In general, using multiple vmas is preferable;
1603 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1604 * impractical.
1605 */
1606int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1607 unsigned long pfn, pgprot_t pgprot)
1608{
1609 int ret;
1610 /*
1611 * Technically, architectures with pte_special can avoid all these
1612 * restrictions (same for remap_pfn_range). However we would like
1613 * consistency in testing and feature parity among all, so we should
1614 * try to keep these invariants in place for everybody.
1615 */
1616 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1617 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1618 (VM_PFNMAP|VM_MIXEDMAP));
1619 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1620 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1621
1622 if (addr < vma->vm_start || addr >= vma->vm_end)
1623 return -EFAULT;
1624 if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
1625 return -EINVAL;
1626
1627 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1628
1629 return ret;
1630}
1631EXPORT_SYMBOL(vm_insert_pfn_prot);
1632
1633int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1634 pfn_t pfn)
1635{
1636 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1637
1638 if (addr < vma->vm_start || addr >= vma->vm_end)
1639 return -EFAULT;
1640
1641 /*
1642 * If we don't have pte special, then we have to use the pfn_valid()
1643 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1644 * refcount the page if pfn_valid is true (hence insert_page rather
1645 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1646 * without pte special, it would there be refcounted as a normal page.
1647 */
1648 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1649 struct page *page;
1650
1651 /*
1652 * At this point we are committed to insert_page()
1653 * regardless of whether the caller specified flags that
1654 * result in pfn_t_has_page() == false.
1655 */
1656 page = pfn_to_page(pfn_t_to_pfn(pfn));
1657 return insert_page(vma, addr, page, vma->vm_page_prot);
1658 }
1659 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1660}
1661EXPORT_SYMBOL(vm_insert_mixed);
1662
1663/*
1664 * maps a range of physical memory into the requested pages. the old
1665 * mappings are removed. any references to nonexistent pages results
1666 * in null mappings (currently treated as "copy-on-access")
1667 */
1668static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1669 unsigned long addr, unsigned long end,
1670 unsigned long pfn, pgprot_t prot)
1671{
1672 pte_t *pte;
1673 spinlock_t *ptl;
1674
1675 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1676 if (!pte)
1677 return -ENOMEM;
1678 arch_enter_lazy_mmu_mode();
1679 do {
1680 BUG_ON(!pte_none(*pte));
1681 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1682 pfn++;
1683 } while (pte++, addr += PAGE_SIZE, addr != end);
1684 arch_leave_lazy_mmu_mode();
1685 pte_unmap_unlock(pte - 1, ptl);
1686 return 0;
1687}
1688
1689static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1690 unsigned long addr, unsigned long end,
1691 unsigned long pfn, pgprot_t prot)
1692{
1693 pmd_t *pmd;
1694 unsigned long next;
1695
1696 pfn -= addr >> PAGE_SHIFT;
1697 pmd = pmd_alloc(mm, pud, addr);
1698 if (!pmd)
1699 return -ENOMEM;
1700 VM_BUG_ON(pmd_trans_huge(*pmd));
1701 do {
1702 next = pmd_addr_end(addr, end);
1703 if (remap_pte_range(mm, pmd, addr, next,
1704 pfn + (addr >> PAGE_SHIFT), prot))
1705 return -ENOMEM;
1706 } while (pmd++, addr = next, addr != end);
1707 return 0;
1708}
1709
1710static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1711 unsigned long addr, unsigned long end,
1712 unsigned long pfn, pgprot_t prot)
1713{
1714 pud_t *pud;
1715 unsigned long next;
1716
1717 pfn -= addr >> PAGE_SHIFT;
1718 pud = pud_alloc(mm, pgd, addr);
1719 if (!pud)
1720 return -ENOMEM;
1721 do {
1722 next = pud_addr_end(addr, end);
1723 if (remap_pmd_range(mm, pud, addr, next,
1724 pfn + (addr >> PAGE_SHIFT), prot))
1725 return -ENOMEM;
1726 } while (pud++, addr = next, addr != end);
1727 return 0;
1728}
1729
1730/**
1731 * remap_pfn_range - remap kernel memory to userspace
1732 * @vma: user vma to map to
1733 * @addr: target user address to start at
1734 * @pfn: physical address of kernel memory
1735 * @size: size of map area
1736 * @prot: page protection flags for this mapping
1737 *
1738 * Note: this is only safe if the mm semaphore is held when called.
1739 */
1740int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1741 unsigned long pfn, unsigned long size, pgprot_t prot)
1742{
1743 pgd_t *pgd;
1744 unsigned long next;
1745 unsigned long end = addr + PAGE_ALIGN(size);
1746 struct mm_struct *mm = vma->vm_mm;
1747 int err;
1748
1749 /*
1750 * Physically remapped pages are special. Tell the
1751 * rest of the world about it:
1752 * VM_IO tells people not to look at these pages
1753 * (accesses can have side effects).
1754 * VM_PFNMAP tells the core MM that the base pages are just
1755 * raw PFN mappings, and do not have a "struct page" associated
1756 * with them.
1757 * VM_DONTEXPAND
1758 * Disable vma merging and expanding with mremap().
1759 * VM_DONTDUMP
1760 * Omit vma from core dump, even when VM_IO turned off.
1761 *
1762 * There's a horrible special case to handle copy-on-write
1763 * behaviour that some programs depend on. We mark the "original"
1764 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1765 * See vm_normal_page() for details.
1766 */
1767 if (is_cow_mapping(vma->vm_flags)) {
1768 if (addr != vma->vm_start || end != vma->vm_end)
1769 return -EINVAL;
1770 vma->vm_pgoff = pfn;
1771 }
1772
1773 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
1774 if (err)
1775 return -EINVAL;
1776
1777 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1778
1779 BUG_ON(addr >= end);
1780 pfn -= addr >> PAGE_SHIFT;
1781 pgd = pgd_offset(mm, addr);
1782 flush_cache_range(vma, addr, end);
1783 do {
1784 next = pgd_addr_end(addr, end);
1785 err = remap_pud_range(mm, pgd, addr, next,
1786 pfn + (addr >> PAGE_SHIFT), prot);
1787 if (err)
1788 break;
1789 } while (pgd++, addr = next, addr != end);
1790
1791 if (err)
1792 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1793
1794 return err;
1795}
1796EXPORT_SYMBOL(remap_pfn_range);
1797
1798/**
1799 * vm_iomap_memory - remap memory to userspace
1800 * @vma: user vma to map to
1801 * @start: start of area
1802 * @len: size of area
1803 *
1804 * This is a simplified io_remap_pfn_range() for common driver use. The
1805 * driver just needs to give us the physical memory range to be mapped,
1806 * we'll figure out the rest from the vma information.
1807 *
1808 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1809 * whatever write-combining details or similar.
1810 */
1811int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1812{
1813 unsigned long vm_len, pfn, pages;
1814
1815 /* Check that the physical memory area passed in looks valid */
1816 if (start + len < start)
1817 return -EINVAL;
1818 /*
1819 * You *really* shouldn't map things that aren't page-aligned,
1820 * but we've historically allowed it because IO memory might
1821 * just have smaller alignment.
1822 */
1823 len += start & ~PAGE_MASK;
1824 pfn = start >> PAGE_SHIFT;
1825 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1826 if (pfn + pages < pfn)
1827 return -EINVAL;
1828
1829 /* We start the mapping 'vm_pgoff' pages into the area */
1830 if (vma->vm_pgoff > pages)
1831 return -EINVAL;
1832 pfn += vma->vm_pgoff;
1833 pages -= vma->vm_pgoff;
1834
1835 /* Can we fit all of the mapping? */
1836 vm_len = vma->vm_end - vma->vm_start;
1837 if (vm_len >> PAGE_SHIFT > pages)
1838 return -EINVAL;
1839
1840 /* Ok, let it rip */
1841 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1842}
1843EXPORT_SYMBOL(vm_iomap_memory);
1844
1845static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1846 unsigned long addr, unsigned long end,
1847 pte_fn_t fn, void *data)
1848{
1849 pte_t *pte;
1850 int err;
1851 pgtable_t token;
1852 spinlock_t *uninitialized_var(ptl);
1853
1854 pte = (mm == &init_mm) ?
1855 pte_alloc_kernel(pmd, addr) :
1856 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1857 if (!pte)
1858 return -ENOMEM;
1859
1860 BUG_ON(pmd_huge(*pmd));
1861
1862 arch_enter_lazy_mmu_mode();
1863
1864 token = pmd_pgtable(*pmd);
1865
1866 do {
1867 err = fn(pte++, token, addr, data);
1868 if (err)
1869 break;
1870 } while (addr += PAGE_SIZE, addr != end);
1871
1872 arch_leave_lazy_mmu_mode();
1873
1874 if (mm != &init_mm)
1875 pte_unmap_unlock(pte-1, ptl);
1876 return err;
1877}
1878
1879static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1880 unsigned long addr, unsigned long end,
1881 pte_fn_t fn, void *data)
1882{
1883 pmd_t *pmd;
1884 unsigned long next;
1885 int err;
1886
1887 BUG_ON(pud_huge(*pud));
1888
1889 pmd = pmd_alloc(mm, pud, addr);
1890 if (!pmd)
1891 return -ENOMEM;
1892 do {
1893 next = pmd_addr_end(addr, end);
1894 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1895 if (err)
1896 break;
1897 } while (pmd++, addr = next, addr != end);
1898 return err;
1899}
1900
1901static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1902 unsigned long addr, unsigned long end,
1903 pte_fn_t fn, void *data)
1904{
1905 pud_t *pud;
1906 unsigned long next;
1907 int err;
1908
1909 pud = pud_alloc(mm, pgd, addr);
1910 if (!pud)
1911 return -ENOMEM;
1912 do {
1913 next = pud_addr_end(addr, end);
1914 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1915 if (err)
1916 break;
1917 } while (pud++, addr = next, addr != end);
1918 return err;
1919}
1920
1921/*
1922 * Scan a region of virtual memory, filling in page tables as necessary
1923 * and calling a provided function on each leaf page table.
1924 */
1925int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1926 unsigned long size, pte_fn_t fn, void *data)
1927{
1928 pgd_t *pgd;
1929 unsigned long next;
1930 unsigned long end = addr + size;
1931 int err;
1932
1933 if (WARN_ON(addr >= end))
1934 return -EINVAL;
1935
1936 pgd = pgd_offset(mm, addr);
1937 do {
1938 next = pgd_addr_end(addr, end);
1939 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1940 if (err)
1941 break;
1942 } while (pgd++, addr = next, addr != end);
1943
1944 return err;
1945}
1946EXPORT_SYMBOL_GPL(apply_to_page_range);
1947
1948/*
1949 * handle_pte_fault chooses page fault handler according to an entry which was
1950 * read non-atomically. Before making any commitment, on those architectures
1951 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
1952 * parts, do_swap_page must check under lock before unmapping the pte and
1953 * proceeding (but do_wp_page is only called after already making such a check;
1954 * and do_anonymous_page can safely check later on).
1955 */
1956static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1957 pte_t *page_table, pte_t orig_pte)
1958{
1959 int same = 1;
1960#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1961 if (sizeof(pte_t) > sizeof(unsigned long)) {
1962 spinlock_t *ptl = pte_lockptr(mm, pmd);
1963 spin_lock(ptl);
1964 same = pte_same(*page_table, orig_pte);
1965 spin_unlock(ptl);
1966 }
1967#endif
1968 pte_unmap(page_table);
1969 return same;
1970}
1971
1972static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1973{
1974 debug_dma_assert_idle(src);
1975
1976 /*
1977 * If the source page was a PFN mapping, we don't have
1978 * a "struct page" for it. We do a best-effort copy by
1979 * just copying from the original user address. If that
1980 * fails, we just zero-fill it. Live with it.
1981 */
1982 if (unlikely(!src)) {
1983 void *kaddr = kmap_atomic(dst);
1984 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1985
1986 /*
1987 * This really shouldn't fail, because the page is there
1988 * in the page tables. But it might just be unreadable,
1989 * in which case we just give up and fill the result with
1990 * zeroes.
1991 */
1992 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1993 clear_page(kaddr);
1994 kunmap_atomic(kaddr);
1995 flush_dcache_page(dst);
1996 } else
1997 copy_user_highpage(dst, src, va, vma);
1998}
1999
2000static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2001{
2002 struct file *vm_file = vma->vm_file;
2003
2004 if (vm_file)
2005 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2006
2007 /*
2008 * Special mappings (e.g. VDSO) do not have any file so fake
2009 * a default GFP_KERNEL for them.
2010 */
2011 return GFP_KERNEL;
2012}
2013
2014/*
2015 * Notify the address space that the page is about to become writable so that
2016 * it can prohibit this or wait for the page to get into an appropriate state.
2017 *
2018 * We do this without the lock held, so that it can sleep if it needs to.
2019 */
2020static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
2021 unsigned long address)
2022{
2023 struct vm_fault vmf;
2024 int ret;
2025
2026 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2027 vmf.pgoff = page->index;
2028 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2029 vmf.gfp_mask = __get_fault_gfp_mask(vma);
2030 vmf.page = page;
2031 vmf.cow_page = NULL;
2032
2033 ret = vma->vm_ops->page_mkwrite(vma, &vmf);
2034 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2035 return ret;
2036 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2037 lock_page(page);
2038 if (!page->mapping) {
2039 unlock_page(page);
2040 return 0; /* retry */
2041 }
2042 ret |= VM_FAULT_LOCKED;
2043 } else
2044 VM_BUG_ON_PAGE(!PageLocked(page), page);
2045 return ret;
2046}
2047
2048/*
2049 * Handle write page faults for pages that can be reused in the current vma
2050 *
2051 * This can happen either due to the mapping being with the VM_SHARED flag,
2052 * or due to us being the last reference standing to the page. In either
2053 * case, all we need to do here is to mark the page as writable and update
2054 * any related book-keeping.
2055 */
2056static inline int wp_page_reuse(struct mm_struct *mm,
2057 struct vm_area_struct *vma, unsigned long address,
2058 pte_t *page_table, spinlock_t *ptl, pte_t orig_pte,
2059 struct page *page, int page_mkwrite,
2060 int dirty_shared)
2061 __releases(ptl)
2062{
2063 pte_t entry;
2064 /*
2065 * Clear the pages cpupid information as the existing
2066 * information potentially belongs to a now completely
2067 * unrelated process.
2068 */
2069 if (page)
2070 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2071
2072 flush_cache_page(vma, address, pte_pfn(orig_pte));
2073 entry = pte_mkyoung(orig_pte);
2074 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2075 if (ptep_set_access_flags(vma, address, page_table, entry, 1))
2076 update_mmu_cache(vma, address, page_table);
2077 pte_unmap_unlock(page_table, ptl);
2078
2079 if (dirty_shared) {
2080 struct address_space *mapping;
2081 int dirtied;
2082
2083 if (!page_mkwrite)
2084 lock_page(page);
2085
2086 dirtied = set_page_dirty(page);
2087 VM_BUG_ON_PAGE(PageAnon(page), page);
2088 mapping = page->mapping;
2089 unlock_page(page);
2090 put_page(page);
2091
2092 if ((dirtied || page_mkwrite) && mapping) {
2093 /*
2094 * Some device drivers do not set page.mapping
2095 * but still dirty their pages
2096 */
2097 balance_dirty_pages_ratelimited(mapping);
2098 }
2099
2100 if (!page_mkwrite)
2101 file_update_time(vma->vm_file);
2102 }
2103
2104 return VM_FAULT_WRITE;
2105}
2106
2107/*
2108 * Handle the case of a page which we actually need to copy to a new page.
2109 *
2110 * Called with mmap_sem locked and the old page referenced, but
2111 * without the ptl held.
2112 *
2113 * High level logic flow:
2114 *
2115 * - Allocate a page, copy the content of the old page to the new one.
2116 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2117 * - Take the PTL. If the pte changed, bail out and release the allocated page
2118 * - If the pte is still the way we remember it, update the page table and all
2119 * relevant references. This includes dropping the reference the page-table
2120 * held to the old page, as well as updating the rmap.
2121 * - In any case, unlock the PTL and drop the reference we took to the old page.
2122 */
2123static int wp_page_copy(struct mm_struct *mm, struct vm_area_struct *vma,
2124 unsigned long address, pte_t *page_table, pmd_t *pmd,
2125 pte_t orig_pte, struct page *old_page)
2126{
2127 struct page *new_page = NULL;
2128 spinlock_t *ptl = NULL;
2129 pte_t entry;
2130 int page_copied = 0;
2131 const unsigned long mmun_start = address & PAGE_MASK; /* For mmu_notifiers */
2132 const unsigned long mmun_end = mmun_start + PAGE_SIZE; /* For mmu_notifiers */
2133 struct mem_cgroup *memcg;
2134
2135 if (unlikely(anon_vma_prepare(vma)))
2136 goto oom;
2137
2138 if (is_zero_pfn(pte_pfn(orig_pte))) {
2139 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2140 if (!new_page)
2141 goto oom;
2142 } else {
2143 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2144 if (!new_page)
2145 goto oom;
2146 cow_user_page(new_page, old_page, address, vma);
2147 }
2148
2149 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2150 goto oom_free_new;
2151
2152 __SetPageUptodate(new_page);
2153
2154 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2155
2156 /*
2157 * Re-check the pte - we dropped the lock
2158 */
2159 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2160 if (likely(pte_same(*page_table, orig_pte))) {
2161 if (old_page) {
2162 if (!PageAnon(old_page)) {
2163 dec_mm_counter_fast(mm,
2164 mm_counter_file(old_page));
2165 inc_mm_counter_fast(mm, MM_ANONPAGES);
2166 }
2167 } else {
2168 inc_mm_counter_fast(mm, MM_ANONPAGES);
2169 }
2170 flush_cache_page(vma, address, pte_pfn(orig_pte));
2171 entry = mk_pte(new_page, vma->vm_page_prot);
2172 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2173 /*
2174 * Clear the pte entry and flush it first, before updating the
2175 * pte with the new entry. This will avoid a race condition
2176 * seen in the presence of one thread doing SMC and another
2177 * thread doing COW.
2178 */
2179 ptep_clear_flush_notify(vma, address, page_table);
2180 page_add_new_anon_rmap(new_page, vma, address, false);
2181 mem_cgroup_commit_charge(new_page, memcg, false, false);
2182 lru_cache_add_active_or_unevictable(new_page, vma);
2183 /*
2184 * We call the notify macro here because, when using secondary
2185 * mmu page tables (such as kvm shadow page tables), we want the
2186 * new page to be mapped directly into the secondary page table.
2187 */
2188 set_pte_at_notify(mm, address, page_table, entry);
2189 update_mmu_cache(vma, address, page_table);
2190 if (old_page) {
2191 /*
2192 * Only after switching the pte to the new page may
2193 * we remove the mapcount here. Otherwise another
2194 * process may come and find the rmap count decremented
2195 * before the pte is switched to the new page, and
2196 * "reuse" the old page writing into it while our pte
2197 * here still points into it and can be read by other
2198 * threads.
2199 *
2200 * The critical issue is to order this
2201 * page_remove_rmap with the ptp_clear_flush above.
2202 * Those stores are ordered by (if nothing else,)
2203 * the barrier present in the atomic_add_negative
2204 * in page_remove_rmap.
2205 *
2206 * Then the TLB flush in ptep_clear_flush ensures that
2207 * no process can access the old page before the
2208 * decremented mapcount is visible. And the old page
2209 * cannot be reused until after the decremented
2210 * mapcount is visible. So transitively, TLBs to
2211 * old page will be flushed before it can be reused.
2212 */
2213 page_remove_rmap(old_page, false);
2214 }
2215
2216 /* Free the old page.. */
2217 new_page = old_page;
2218 page_copied = 1;
2219 } else {
2220 mem_cgroup_cancel_charge(new_page, memcg, false);
2221 }
2222
2223 if (new_page)
2224 put_page(new_page);
2225
2226 pte_unmap_unlock(page_table, ptl);
2227 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2228 if (old_page) {
2229 /*
2230 * Don't let another task, with possibly unlocked vma,
2231 * keep the mlocked page.
2232 */
2233 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2234 lock_page(old_page); /* LRU manipulation */
2235 if (PageMlocked(old_page))
2236 munlock_vma_page(old_page);
2237 unlock_page(old_page);
2238 }
2239 put_page(old_page);
2240 }
2241 return page_copied ? VM_FAULT_WRITE : 0;
2242oom_free_new:
2243 put_page(new_page);
2244oom:
2245 if (old_page)
2246 put_page(old_page);
2247 return VM_FAULT_OOM;
2248}
2249
2250/*
2251 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2252 * mapping
2253 */
2254static int wp_pfn_shared(struct mm_struct *mm,
2255 struct vm_area_struct *vma, unsigned long address,
2256 pte_t *page_table, spinlock_t *ptl, pte_t orig_pte,
2257 pmd_t *pmd)
2258{
2259 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2260 struct vm_fault vmf = {
2261 .page = NULL,
2262 .pgoff = linear_page_index(vma, address),
2263 .virtual_address = (void __user *)(address & PAGE_MASK),
2264 .flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
2265 };
2266 int ret;
2267
2268 pte_unmap_unlock(page_table, ptl);
2269 ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
2270 if (ret & VM_FAULT_ERROR)
2271 return ret;
2272 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2273 /*
2274 * We might have raced with another page fault while we
2275 * released the pte_offset_map_lock.
2276 */
2277 if (!pte_same(*page_table, orig_pte)) {
2278 pte_unmap_unlock(page_table, ptl);
2279 return 0;
2280 }
2281 }
2282 return wp_page_reuse(mm, vma, address, page_table, ptl, orig_pte,
2283 NULL, 0, 0);
2284}
2285
2286static int wp_page_shared(struct mm_struct *mm, struct vm_area_struct *vma,
2287 unsigned long address, pte_t *page_table,
2288 pmd_t *pmd, spinlock_t *ptl, pte_t orig_pte,
2289 struct page *old_page)
2290 __releases(ptl)
2291{
2292 int page_mkwrite = 0;
2293
2294 get_page(old_page);
2295
2296 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2297 int tmp;
2298
2299 pte_unmap_unlock(page_table, ptl);
2300 tmp = do_page_mkwrite(vma, old_page, address);
2301 if (unlikely(!tmp || (tmp &
2302 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2303 put_page(old_page);
2304 return tmp;
2305 }
2306 /*
2307 * Since we dropped the lock we need to revalidate
2308 * the PTE as someone else may have changed it. If
2309 * they did, we just return, as we can count on the
2310 * MMU to tell us if they didn't also make it writable.
2311 */
2312 page_table = pte_offset_map_lock(mm, pmd, address,
2313 &ptl);
2314 if (!pte_same(*page_table, orig_pte)) {
2315 unlock_page(old_page);
2316 pte_unmap_unlock(page_table, ptl);
2317 put_page(old_page);
2318 return 0;
2319 }
2320 page_mkwrite = 1;
2321 }
2322
2323 return wp_page_reuse(mm, vma, address, page_table, ptl,
2324 orig_pte, old_page, page_mkwrite, 1);
2325}
2326
2327/*
2328 * This routine handles present pages, when users try to write
2329 * to a shared page. It is done by copying the page to a new address
2330 * and decrementing the shared-page counter for the old page.
2331 *
2332 * Note that this routine assumes that the protection checks have been
2333 * done by the caller (the low-level page fault routine in most cases).
2334 * Thus we can safely just mark it writable once we've done any necessary
2335 * COW.
2336 *
2337 * We also mark the page dirty at this point even though the page will
2338 * change only once the write actually happens. This avoids a few races,
2339 * and potentially makes it more efficient.
2340 *
2341 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2342 * but allow concurrent faults), with pte both mapped and locked.
2343 * We return with mmap_sem still held, but pte unmapped and unlocked.
2344 */
2345static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2346 unsigned long address, pte_t *page_table, pmd_t *pmd,
2347 spinlock_t *ptl, pte_t orig_pte)
2348 __releases(ptl)
2349{
2350 struct page *old_page;
2351
2352 old_page = vm_normal_page(vma, address, orig_pte);
2353 if (!old_page) {
2354 /*
2355 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2356 * VM_PFNMAP VMA.
2357 *
2358 * We should not cow pages in a shared writeable mapping.
2359 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2360 */
2361 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2362 (VM_WRITE|VM_SHARED))
2363 return wp_pfn_shared(mm, vma, address, page_table, ptl,
2364 orig_pte, pmd);
2365
2366 pte_unmap_unlock(page_table, ptl);
2367 return wp_page_copy(mm, vma, address, page_table, pmd,
2368 orig_pte, old_page);
2369 }
2370
2371 /*
2372 * Take out anonymous pages first, anonymous shared vmas are
2373 * not dirty accountable.
2374 */
2375 if (PageAnon(old_page) && !PageKsm(old_page)) {
2376 int total_mapcount;
2377 if (!trylock_page(old_page)) {
2378 get_page(old_page);
2379 pte_unmap_unlock(page_table, ptl);
2380 lock_page(old_page);
2381 page_table = pte_offset_map_lock(mm, pmd, address,
2382 &ptl);
2383 if (!pte_same(*page_table, orig_pte)) {
2384 unlock_page(old_page);
2385 pte_unmap_unlock(page_table, ptl);
2386 put_page(old_page);
2387 return 0;
2388 }
2389 put_page(old_page);
2390 }
2391 if (reuse_swap_page(old_page, &total_mapcount)) {
2392 if (total_mapcount == 1) {
2393 /*
2394 * The page is all ours. Move it to
2395 * our anon_vma so the rmap code will
2396 * not search our parent or siblings.
2397 * Protected against the rmap code by
2398 * the page lock.
2399 */
2400 page_move_anon_rmap(compound_head(old_page),
2401 vma, address);
2402 }
2403 unlock_page(old_page);
2404 return wp_page_reuse(mm, vma, address, page_table, ptl,
2405 orig_pte, old_page, 0, 0);
2406 }
2407 unlock_page(old_page);
2408 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2409 (VM_WRITE|VM_SHARED))) {
2410 return wp_page_shared(mm, vma, address, page_table, pmd,
2411 ptl, orig_pte, old_page);
2412 }
2413
2414 /*
2415 * Ok, we need to copy. Oh, well..
2416 */
2417 get_page(old_page);
2418
2419 pte_unmap_unlock(page_table, ptl);
2420 return wp_page_copy(mm, vma, address, page_table, pmd,
2421 orig_pte, old_page);
2422}
2423
2424static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2425 unsigned long start_addr, unsigned long end_addr,
2426 struct zap_details *details)
2427{
2428 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2429}
2430
2431static inline void unmap_mapping_range_tree(struct rb_root *root,
2432 struct zap_details *details)
2433{
2434 struct vm_area_struct *vma;
2435 pgoff_t vba, vea, zba, zea;
2436
2437 vma_interval_tree_foreach(vma, root,
2438 details->first_index, details->last_index) {
2439
2440 vba = vma->vm_pgoff;
2441 vea = vba + vma_pages(vma) - 1;
2442 zba = details->first_index;
2443 if (zba < vba)
2444 zba = vba;
2445 zea = details->last_index;
2446 if (zea > vea)
2447 zea = vea;
2448
2449 unmap_mapping_range_vma(vma,
2450 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2451 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2452 details);
2453 }
2454}
2455
2456/**
2457 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2458 * address_space corresponding to the specified page range in the underlying
2459 * file.
2460 *
2461 * @mapping: the address space containing mmaps to be unmapped.
2462 * @holebegin: byte in first page to unmap, relative to the start of
2463 * the underlying file. This will be rounded down to a PAGE_SIZE
2464 * boundary. Note that this is different from truncate_pagecache(), which
2465 * must keep the partial page. In contrast, we must get rid of
2466 * partial pages.
2467 * @holelen: size of prospective hole in bytes. This will be rounded
2468 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2469 * end of the file.
2470 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2471 * but 0 when invalidating pagecache, don't throw away private data.
2472 */
2473void unmap_mapping_range(struct address_space *mapping,
2474 loff_t const holebegin, loff_t const holelen, int even_cows)
2475{
2476 struct zap_details details = { };
2477 pgoff_t hba = holebegin >> PAGE_SHIFT;
2478 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2479
2480 /* Check for overflow. */
2481 if (sizeof(holelen) > sizeof(hlen)) {
2482 long long holeend =
2483 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2484 if (holeend & ~(long long)ULONG_MAX)
2485 hlen = ULONG_MAX - hba + 1;
2486 }
2487
2488 details.check_mapping = even_cows? NULL: mapping;
2489 details.first_index = hba;
2490 details.last_index = hba + hlen - 1;
2491 if (details.last_index < details.first_index)
2492 details.last_index = ULONG_MAX;
2493
2494
2495 /* DAX uses i_mmap_lock to serialise file truncate vs page fault */
2496 i_mmap_lock_write(mapping);
2497 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2498 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2499 i_mmap_unlock_write(mapping);
2500}
2501EXPORT_SYMBOL(unmap_mapping_range);
2502
2503/*
2504 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2505 * but allow concurrent faults), and pte mapped but not yet locked.
2506 * We return with pte unmapped and unlocked.
2507 *
2508 * We return with the mmap_sem locked or unlocked in the same cases
2509 * as does filemap_fault().
2510 */
2511static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2512 unsigned long address, pte_t *page_table, pmd_t *pmd,
2513 unsigned int flags, pte_t orig_pte)
2514{
2515 spinlock_t *ptl;
2516 struct page *page, *swapcache;
2517 struct mem_cgroup *memcg;
2518 swp_entry_t entry;
2519 pte_t pte;
2520 int locked;
2521 int exclusive = 0;
2522 int ret = 0;
2523
2524 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2525 goto out;
2526
2527 entry = pte_to_swp_entry(orig_pte);
2528 if (unlikely(non_swap_entry(entry))) {
2529 if (is_migration_entry(entry)) {
2530 migration_entry_wait(mm, pmd, address);
2531 } else if (is_hwpoison_entry(entry)) {
2532 ret = VM_FAULT_HWPOISON;
2533 } else {
2534 print_bad_pte(vma, address, orig_pte, NULL);
2535 ret = VM_FAULT_SIGBUS;
2536 }
2537 goto out;
2538 }
2539 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2540 page = lookup_swap_cache(entry);
2541 if (!page) {
2542 page = swapin_readahead(entry,
2543 GFP_HIGHUSER_MOVABLE, vma, address);
2544 if (!page) {
2545 /*
2546 * Back out if somebody else faulted in this pte
2547 * while we released the pte lock.
2548 */
2549 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2550 if (likely(pte_same(*page_table, orig_pte)))
2551 ret = VM_FAULT_OOM;
2552 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2553 goto unlock;
2554 }
2555
2556 /* Had to read the page from swap area: Major fault */
2557 ret = VM_FAULT_MAJOR;
2558 count_vm_event(PGMAJFAULT);
2559 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2560 } else if (PageHWPoison(page)) {
2561 /*
2562 * hwpoisoned dirty swapcache pages are kept for killing
2563 * owner processes (which may be unknown at hwpoison time)
2564 */
2565 ret = VM_FAULT_HWPOISON;
2566 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2567 swapcache = page;
2568 goto out_release;
2569 }
2570
2571 swapcache = page;
2572 locked = lock_page_or_retry(page, mm, flags);
2573
2574 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2575 if (!locked) {
2576 ret |= VM_FAULT_RETRY;
2577 goto out_release;
2578 }
2579
2580 /*
2581 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2582 * release the swapcache from under us. The page pin, and pte_same
2583 * test below, are not enough to exclude that. Even if it is still
2584 * swapcache, we need to check that the page's swap has not changed.
2585 */
2586 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2587 goto out_page;
2588
2589 page = ksm_might_need_to_copy(page, vma, address);
2590 if (unlikely(!page)) {
2591 ret = VM_FAULT_OOM;
2592 page = swapcache;
2593 goto out_page;
2594 }
2595
2596 if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg, false)) {
2597 ret = VM_FAULT_OOM;
2598 goto out_page;
2599 }
2600
2601 /*
2602 * Back out if somebody else already faulted in this pte.
2603 */
2604 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2605 if (unlikely(!pte_same(*page_table, orig_pte)))
2606 goto out_nomap;
2607
2608 if (unlikely(!PageUptodate(page))) {
2609 ret = VM_FAULT_SIGBUS;
2610 goto out_nomap;
2611 }
2612
2613 /*
2614 * The page isn't present yet, go ahead with the fault.
2615 *
2616 * Be careful about the sequence of operations here.
2617 * To get its accounting right, reuse_swap_page() must be called
2618 * while the page is counted on swap but not yet in mapcount i.e.
2619 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2620 * must be called after the swap_free(), or it will never succeed.
2621 */
2622
2623 inc_mm_counter_fast(mm, MM_ANONPAGES);
2624 dec_mm_counter_fast(mm, MM_SWAPENTS);
2625 pte = mk_pte(page, vma->vm_page_prot);
2626 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2627 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2628 flags &= ~FAULT_FLAG_WRITE;
2629 ret |= VM_FAULT_WRITE;
2630 exclusive = RMAP_EXCLUSIVE;
2631 }
2632 flush_icache_page(vma, page);
2633 if (pte_swp_soft_dirty(orig_pte))
2634 pte = pte_mksoft_dirty(pte);
2635 set_pte_at(mm, address, page_table, pte);
2636 if (page == swapcache) {
2637 do_page_add_anon_rmap(page, vma, address, exclusive);
2638 mem_cgroup_commit_charge(page, memcg, true, false);
2639 } else { /* ksm created a completely new copy */
2640 page_add_new_anon_rmap(page, vma, address, false);
2641 mem_cgroup_commit_charge(page, memcg, false, false);
2642 lru_cache_add_active_or_unevictable(page, vma);
2643 }
2644
2645 swap_free(entry);
2646 if (mem_cgroup_swap_full(page) ||
2647 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2648 try_to_free_swap(page);
2649 unlock_page(page);
2650 if (page != swapcache) {
2651 /*
2652 * Hold the lock to avoid the swap entry to be reused
2653 * until we take the PT lock for the pte_same() check
2654 * (to avoid false positives from pte_same). For
2655 * further safety release the lock after the swap_free
2656 * so that the swap count won't change under a
2657 * parallel locked swapcache.
2658 */
2659 unlock_page(swapcache);
2660 put_page(swapcache);
2661 }
2662
2663 if (flags & FAULT_FLAG_WRITE) {
2664 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2665 if (ret & VM_FAULT_ERROR)
2666 ret &= VM_FAULT_ERROR;
2667 goto out;
2668 }
2669
2670 /* No need to invalidate - it was non-present before */
2671 update_mmu_cache(vma, address, page_table);
2672unlock:
2673 pte_unmap_unlock(page_table, ptl);
2674out:
2675 return ret;
2676out_nomap:
2677 mem_cgroup_cancel_charge(page, memcg, false);
2678 pte_unmap_unlock(page_table, ptl);
2679out_page:
2680 unlock_page(page);
2681out_release:
2682 put_page(page);
2683 if (page != swapcache) {
2684 unlock_page(swapcache);
2685 put_page(swapcache);
2686 }
2687 return ret;
2688}
2689
2690/*
2691 * This is like a special single-page "expand_{down|up}wards()",
2692 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2693 * doesn't hit another vma.
2694 */
2695static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2696{
2697 address &= PAGE_MASK;
2698 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2699 struct vm_area_struct *prev = vma->vm_prev;
2700
2701 /*
2702 * Is there a mapping abutting this one below?
2703 *
2704 * That's only ok if it's the same stack mapping
2705 * that has gotten split..
2706 */
2707 if (prev && prev->vm_end == address)
2708 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2709
2710 return expand_downwards(vma, address - PAGE_SIZE);
2711 }
2712 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2713 struct vm_area_struct *next = vma->vm_next;
2714
2715 /* As VM_GROWSDOWN but s/below/above/ */
2716 if (next && next->vm_start == address + PAGE_SIZE)
2717 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2718
2719 return expand_upwards(vma, address + PAGE_SIZE);
2720 }
2721 return 0;
2722}
2723
2724/*
2725 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2726 * but allow concurrent faults), and pte mapped but not yet locked.
2727 * We return with mmap_sem still held, but pte unmapped and unlocked.
2728 */
2729static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2730 unsigned long address, pte_t *page_table, pmd_t *pmd,
2731 unsigned int flags)
2732{
2733 struct mem_cgroup *memcg;
2734 struct page *page;
2735 spinlock_t *ptl;
2736 pte_t entry;
2737
2738 pte_unmap(page_table);
2739
2740 /* File mapping without ->vm_ops ? */
2741 if (vma->vm_flags & VM_SHARED)
2742 return VM_FAULT_SIGBUS;
2743
2744 /* Check if we need to add a guard page to the stack */
2745 if (check_stack_guard_page(vma, address) < 0)
2746 return VM_FAULT_SIGSEGV;
2747
2748 /* Use the zero-page for reads */
2749 if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
2750 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2751 vma->vm_page_prot));
2752 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2753 if (!pte_none(*page_table))
2754 goto unlock;
2755 /* Deliver the page fault to userland, check inside PT lock */
2756 if (userfaultfd_missing(vma)) {
2757 pte_unmap_unlock(page_table, ptl);
2758 return handle_userfault(vma, address, flags,
2759 VM_UFFD_MISSING);
2760 }
2761 goto setpte;
2762 }
2763
2764 /* Allocate our own private page. */
2765 if (unlikely(anon_vma_prepare(vma)))
2766 goto oom;
2767 page = alloc_zeroed_user_highpage_movable(vma, address);
2768 if (!page)
2769 goto oom;
2770
2771 if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg, false))
2772 goto oom_free_page;
2773
2774 /*
2775 * The memory barrier inside __SetPageUptodate makes sure that
2776 * preceeding stores to the page contents become visible before
2777 * the set_pte_at() write.
2778 */
2779 __SetPageUptodate(page);
2780
2781 entry = mk_pte(page, vma->vm_page_prot);
2782 if (vma->vm_flags & VM_WRITE)
2783 entry = pte_mkwrite(pte_mkdirty(entry));
2784
2785 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2786 if (!pte_none(*page_table))
2787 goto release;
2788
2789 /* Deliver the page fault to userland, check inside PT lock */
2790 if (userfaultfd_missing(vma)) {
2791 pte_unmap_unlock(page_table, ptl);
2792 mem_cgroup_cancel_charge(page, memcg, false);
2793 put_page(page);
2794 return handle_userfault(vma, address, flags,
2795 VM_UFFD_MISSING);
2796 }
2797
2798 inc_mm_counter_fast(mm, MM_ANONPAGES);
2799 page_add_new_anon_rmap(page, vma, address, false);
2800 mem_cgroup_commit_charge(page, memcg, false, false);
2801 lru_cache_add_active_or_unevictable(page, vma);
2802setpte:
2803 set_pte_at(mm, address, page_table, entry);
2804
2805 /* No need to invalidate - it was non-present before */
2806 update_mmu_cache(vma, address, page_table);
2807unlock:
2808 pte_unmap_unlock(page_table, ptl);
2809 return 0;
2810release:
2811 mem_cgroup_cancel_charge(page, memcg, false);
2812 put_page(page);
2813 goto unlock;
2814oom_free_page:
2815 put_page(page);
2816oom:
2817 return VM_FAULT_OOM;
2818}
2819
2820/*
2821 * The mmap_sem must have been held on entry, and may have been
2822 * released depending on flags and vma->vm_ops->fault() return value.
2823 * See filemap_fault() and __lock_page_retry().
2824 */
2825static int __do_fault(struct vm_area_struct *vma, unsigned long address,
2826 pgoff_t pgoff, unsigned int flags,
2827 struct page *cow_page, struct page **page)
2828{
2829 struct vm_fault vmf;
2830 int ret;
2831
2832 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2833 vmf.pgoff = pgoff;
2834 vmf.flags = flags;
2835 vmf.page = NULL;
2836 vmf.gfp_mask = __get_fault_gfp_mask(vma);
2837 vmf.cow_page = cow_page;
2838
2839 ret = vma->vm_ops->fault(vma, &vmf);
2840 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2841 return ret;
2842 if (!vmf.page)
2843 goto out;
2844
2845 if (unlikely(PageHWPoison(vmf.page))) {
2846 if (ret & VM_FAULT_LOCKED)
2847 unlock_page(vmf.page);
2848 put_page(vmf.page);
2849 return VM_FAULT_HWPOISON;
2850 }
2851
2852 if (unlikely(!(ret & VM_FAULT_LOCKED)))
2853 lock_page(vmf.page);
2854 else
2855 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
2856
2857 out:
2858 *page = vmf.page;
2859 return ret;
2860}
2861
2862/**
2863 * do_set_pte - setup new PTE entry for given page and add reverse page mapping.
2864 *
2865 * @vma: virtual memory area
2866 * @address: user virtual address
2867 * @page: page to map
2868 * @pte: pointer to target page table entry
2869 * @write: true, if new entry is writable
2870 * @anon: true, if it's anonymous page
2871 *
2872 * Caller must hold page table lock relevant for @pte.
2873 *
2874 * Target users are page handler itself and implementations of
2875 * vm_ops->map_pages.
2876 */
2877void do_set_pte(struct vm_area_struct *vma, unsigned long address,
2878 struct page *page, pte_t *pte, bool write, bool anon)
2879{
2880 pte_t entry;
2881
2882 flush_icache_page(vma, page);
2883 entry = mk_pte(page, vma->vm_page_prot);
2884 if (write)
2885 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2886 if (anon) {
2887 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2888 page_add_new_anon_rmap(page, vma, address, false);
2889 } else {
2890 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
2891 page_add_file_rmap(page);
2892 }
2893 set_pte_at(vma->vm_mm, address, pte, entry);
2894
2895 /* no need to invalidate: a not-present page won't be cached */
2896 update_mmu_cache(vma, address, pte);
2897}
2898
2899static unsigned long fault_around_bytes __read_mostly =
2900 rounddown_pow_of_two(65536);
2901
2902#ifdef CONFIG_DEBUG_FS
2903static int fault_around_bytes_get(void *data, u64 *val)
2904{
2905 *val = fault_around_bytes;
2906 return 0;
2907}
2908
2909/*
2910 * fault_around_pages() and fault_around_mask() expects fault_around_bytes
2911 * rounded down to nearest page order. It's what do_fault_around() expects to
2912 * see.
2913 */
2914static int fault_around_bytes_set(void *data, u64 val)
2915{
2916 if (val / PAGE_SIZE > PTRS_PER_PTE)
2917 return -EINVAL;
2918 if (val > PAGE_SIZE)
2919 fault_around_bytes = rounddown_pow_of_two(val);
2920 else
2921 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
2922 return 0;
2923}
2924DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
2925 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2926
2927static int __init fault_around_debugfs(void)
2928{
2929 void *ret;
2930
2931 ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
2932 &fault_around_bytes_fops);
2933 if (!ret)
2934 pr_warn("Failed to create fault_around_bytes in debugfs");
2935 return 0;
2936}
2937late_initcall(fault_around_debugfs);
2938#endif
2939
2940/*
2941 * do_fault_around() tries to map few pages around the fault address. The hope
2942 * is that the pages will be needed soon and this will lower the number of
2943 * faults to handle.
2944 *
2945 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
2946 * not ready to be mapped: not up-to-date, locked, etc.
2947 *
2948 * This function is called with the page table lock taken. In the split ptlock
2949 * case the page table lock only protects only those entries which belong to
2950 * the page table corresponding to the fault address.
2951 *
2952 * This function doesn't cross the VMA boundaries, in order to call map_pages()
2953 * only once.
2954 *
2955 * fault_around_pages() defines how many pages we'll try to map.
2956 * do_fault_around() expects it to return a power of two less than or equal to
2957 * PTRS_PER_PTE.
2958 *
2959 * The virtual address of the area that we map is naturally aligned to the
2960 * fault_around_pages() value (and therefore to page order). This way it's
2961 * easier to guarantee that we don't cross page table boundaries.
2962 */
2963static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
2964 pte_t *pte, pgoff_t pgoff, unsigned int flags)
2965{
2966 unsigned long start_addr, nr_pages, mask;
2967 pgoff_t max_pgoff;
2968 struct vm_fault vmf;
2969 int off;
2970
2971 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
2972 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
2973
2974 start_addr = max(address & mask, vma->vm_start);
2975 off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
2976 pte -= off;
2977 pgoff -= off;
2978
2979 /*
2980 * max_pgoff is either end of page table or end of vma
2981 * or fault_around_pages() from pgoff, depending what is nearest.
2982 */
2983 max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
2984 PTRS_PER_PTE - 1;
2985 max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
2986 pgoff + nr_pages - 1);
2987
2988 /* Check if it makes any sense to call ->map_pages */
2989 while (!pte_none(*pte)) {
2990 if (++pgoff > max_pgoff)
2991 return;
2992 start_addr += PAGE_SIZE;
2993 if (start_addr >= vma->vm_end)
2994 return;
2995 pte++;
2996 }
2997
2998 vmf.virtual_address = (void __user *) start_addr;
2999 vmf.pte = pte;
3000 vmf.pgoff = pgoff;
3001 vmf.max_pgoff = max_pgoff;
3002 vmf.flags = flags;
3003 vmf.gfp_mask = __get_fault_gfp_mask(vma);
3004 vma->vm_ops->map_pages(vma, &vmf);
3005}
3006
3007static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3008 unsigned long address, pmd_t *pmd,
3009 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3010{
3011 struct page *fault_page;
3012 spinlock_t *ptl;
3013 pte_t *pte;
3014 int ret = 0;
3015
3016 /*
3017 * Let's call ->map_pages() first and use ->fault() as fallback
3018 * if page by the offset is not ready to be mapped (cold cache or
3019 * something).
3020 */
3021 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3022 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3023 do_fault_around(vma, address, pte, pgoff, flags);
3024 if (!pte_same(*pte, orig_pte))
3025 goto unlock_out;
3026 pte_unmap_unlock(pte, ptl);
3027 }
3028
3029 ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3030 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3031 return ret;
3032
3033 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3034 if (unlikely(!pte_same(*pte, orig_pte))) {
3035 pte_unmap_unlock(pte, ptl);
3036 unlock_page(fault_page);
3037 put_page(fault_page);
3038 return ret;
3039 }
3040 do_set_pte(vma, address, fault_page, pte, false, false);
3041 unlock_page(fault_page);
3042unlock_out:
3043 pte_unmap_unlock(pte, ptl);
3044 return ret;
3045}
3046
3047static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3048 unsigned long address, pmd_t *pmd,
3049 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3050{
3051 struct page *fault_page, *new_page;
3052 struct mem_cgroup *memcg;
3053 spinlock_t *ptl;
3054 pte_t *pte;
3055 int ret;
3056
3057 if (unlikely(anon_vma_prepare(vma)))
3058 return VM_FAULT_OOM;
3059
3060 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3061 if (!new_page)
3062 return VM_FAULT_OOM;
3063
3064 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false)) {
3065 put_page(new_page);
3066 return VM_FAULT_OOM;
3067 }
3068
3069 ret = __do_fault(vma, address, pgoff, flags, new_page, &fault_page);
3070 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3071 goto uncharge_out;
3072
3073 if (fault_page)
3074 copy_user_highpage(new_page, fault_page, address, vma);
3075 __SetPageUptodate(new_page);
3076
3077 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3078 if (unlikely(!pte_same(*pte, orig_pte))) {
3079 pte_unmap_unlock(pte, ptl);
3080 if (fault_page) {
3081 unlock_page(fault_page);
3082 put_page(fault_page);
3083 } else {
3084 /*
3085 * The fault handler has no page to lock, so it holds
3086 * i_mmap_lock for read to protect against truncate.
3087 */
3088 i_mmap_unlock_read(vma->vm_file->f_mapping);
3089 }
3090 goto uncharge_out;
3091 }
3092 do_set_pte(vma, address, new_page, pte, true, true);
3093 mem_cgroup_commit_charge(new_page, memcg, false, false);
3094 lru_cache_add_active_or_unevictable(new_page, vma);
3095 pte_unmap_unlock(pte, ptl);
3096 if (fault_page) {
3097 unlock_page(fault_page);
3098 put_page(fault_page);
3099 } else {
3100 /*
3101 * The fault handler has no page to lock, so it holds
3102 * i_mmap_lock for read to protect against truncate.
3103 */
3104 i_mmap_unlock_read(vma->vm_file->f_mapping);
3105 }
3106 return ret;
3107uncharge_out:
3108 mem_cgroup_cancel_charge(new_page, memcg, false);
3109 put_page(new_page);
3110 return ret;
3111}
3112
3113static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3114 unsigned long address, pmd_t *pmd,
3115 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3116{
3117 struct page *fault_page;
3118 struct address_space *mapping;
3119 spinlock_t *ptl;
3120 pte_t *pte;
3121 int dirtied = 0;
3122 int ret, tmp;
3123
3124 ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3125 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3126 return ret;
3127
3128 /*
3129 * Check if the backing address space wants to know that the page is
3130 * about to become writable
3131 */
3132 if (vma->vm_ops->page_mkwrite) {
3133 unlock_page(fault_page);
3134 tmp = do_page_mkwrite(vma, fault_page, address);
3135 if (unlikely(!tmp ||
3136 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3137 put_page(fault_page);
3138 return tmp;
3139 }
3140 }
3141
3142 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3143 if (unlikely(!pte_same(*pte, orig_pte))) {
3144 pte_unmap_unlock(pte, ptl);
3145 unlock_page(fault_page);
3146 put_page(fault_page);
3147 return ret;
3148 }
3149 do_set_pte(vma, address, fault_page, pte, true, false);
3150 pte_unmap_unlock(pte, ptl);
3151
3152 if (set_page_dirty(fault_page))
3153 dirtied = 1;
3154 /*
3155 * Take a local copy of the address_space - page.mapping may be zeroed
3156 * by truncate after unlock_page(). The address_space itself remains
3157 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
3158 * release semantics to prevent the compiler from undoing this copying.
3159 */
3160 mapping = page_rmapping(fault_page);
3161 unlock_page(fault_page);
3162 if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
3163 /*
3164 * Some device drivers do not set page.mapping but still
3165 * dirty their pages
3166 */
3167 balance_dirty_pages_ratelimited(mapping);
3168 }
3169
3170 if (!vma->vm_ops->page_mkwrite)
3171 file_update_time(vma->vm_file);
3172
3173 return ret;
3174}
3175
3176/*
3177 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3178 * but allow concurrent faults).
3179 * The mmap_sem may have been released depending on flags and our
3180 * return value. See filemap_fault() and __lock_page_or_retry().
3181 */
3182static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3183 unsigned long address, pte_t *page_table, pmd_t *pmd,
3184 unsigned int flags, pte_t orig_pte)
3185{
3186 pgoff_t pgoff = linear_page_index(vma, address);
3187
3188 pte_unmap(page_table);
3189 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3190 if (!vma->vm_ops->fault)
3191 return VM_FAULT_SIGBUS;
3192 if (!(flags & FAULT_FLAG_WRITE))
3193 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3194 orig_pte);
3195 if (!(vma->vm_flags & VM_SHARED))
3196 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3197 orig_pte);
3198 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3199}
3200
3201static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3202 unsigned long addr, int page_nid,
3203 int *flags)
3204{
3205 get_page(page);
3206
3207 count_vm_numa_event(NUMA_HINT_FAULTS);
3208 if (page_nid == numa_node_id()) {
3209 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3210 *flags |= TNF_FAULT_LOCAL;
3211 }
3212
3213 return mpol_misplaced(page, vma, addr);
3214}
3215
3216static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3217 unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
3218{
3219 struct page *page = NULL;
3220 spinlock_t *ptl;
3221 int page_nid = -1;
3222 int last_cpupid;
3223 int target_nid;
3224 bool migrated = false;
3225 bool was_writable = pte_write(pte);
3226 int flags = 0;
3227
3228 /* A PROT_NONE fault should not end up here */
3229 BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
3230
3231 /*
3232 * The "pte" at this point cannot be used safely without
3233 * validation through pte_unmap_same(). It's of NUMA type but
3234 * the pfn may be screwed if the read is non atomic.
3235 *
3236 * We can safely just do a "set_pte_at()", because the old
3237 * page table entry is not accessible, so there would be no
3238 * concurrent hardware modifications to the PTE.
3239 */
3240 ptl = pte_lockptr(mm, pmd);
3241 spin_lock(ptl);
3242 if (unlikely(!pte_same(*ptep, pte))) {
3243 pte_unmap_unlock(ptep, ptl);
3244 goto out;
3245 }
3246
3247 /* Make it present again */
3248 pte = pte_modify(pte, vma->vm_page_prot);
3249 pte = pte_mkyoung(pte);
3250 if (was_writable)
3251 pte = pte_mkwrite(pte);
3252 set_pte_at(mm, addr, ptep, pte);
3253 update_mmu_cache(vma, addr, ptep);
3254
3255 page = vm_normal_page(vma, addr, pte);
3256 if (!page) {
3257 pte_unmap_unlock(ptep, ptl);
3258 return 0;
3259 }
3260
3261 /* TODO: handle PTE-mapped THP */
3262 if (PageCompound(page)) {
3263 pte_unmap_unlock(ptep, ptl);
3264 return 0;
3265 }
3266
3267 /*
3268 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3269 * much anyway since they can be in shared cache state. This misses
3270 * the case where a mapping is writable but the process never writes
3271 * to it but pte_write gets cleared during protection updates and
3272 * pte_dirty has unpredictable behaviour between PTE scan updates,
3273 * background writeback, dirty balancing and application behaviour.
3274 */
3275 if (!(vma->vm_flags & VM_WRITE))
3276 flags |= TNF_NO_GROUP;
3277
3278 /*
3279 * Flag if the page is shared between multiple address spaces. This
3280 * is later used when determining whether to group tasks together
3281 */
3282 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3283 flags |= TNF_SHARED;
3284
3285 last_cpupid = page_cpupid_last(page);
3286 page_nid = page_to_nid(page);
3287 target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3288 pte_unmap_unlock(ptep, ptl);
3289 if (target_nid == -1) {
3290 put_page(page);
3291 goto out;
3292 }
3293
3294 /* Migrate to the requested node */
3295 migrated = migrate_misplaced_page(page, vma, target_nid);
3296 if (migrated) {
3297 page_nid = target_nid;
3298 flags |= TNF_MIGRATED;
3299 } else
3300 flags |= TNF_MIGRATE_FAIL;
3301
3302out:
3303 if (page_nid != -1)
3304 task_numa_fault(last_cpupid, page_nid, 1, flags);
3305 return 0;
3306}
3307
3308static int create_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
3309 unsigned long address, pmd_t *pmd, unsigned int flags)
3310{
3311 if (vma_is_anonymous(vma))
3312 return do_huge_pmd_anonymous_page(mm, vma, address, pmd, flags);
3313 if (vma->vm_ops->pmd_fault)
3314 return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
3315 return VM_FAULT_FALLBACK;
3316}
3317
3318static int wp_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
3319 unsigned long address, pmd_t *pmd, pmd_t orig_pmd,
3320 unsigned int flags)
3321{
3322 if (vma_is_anonymous(vma))
3323 return do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd);
3324 if (vma->vm_ops->pmd_fault)
3325 return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
3326 return VM_FAULT_FALLBACK;
3327}
3328
3329/*
3330 * These routines also need to handle stuff like marking pages dirty
3331 * and/or accessed for architectures that don't do it in hardware (most
3332 * RISC architectures). The early dirtying is also good on the i386.
3333 *
3334 * There is also a hook called "update_mmu_cache()" that architectures
3335 * with external mmu caches can use to update those (ie the Sparc or
3336 * PowerPC hashed page tables that act as extended TLBs).
3337 *
3338 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3339 * but allow concurrent faults), and pte mapped but not yet locked.
3340 * We return with pte unmapped and unlocked.
3341 *
3342 * The mmap_sem may have been released depending on flags and our
3343 * return value. See filemap_fault() and __lock_page_or_retry().
3344 */
3345static int handle_pte_fault(struct mm_struct *mm,
3346 struct vm_area_struct *vma, unsigned long address,
3347 pte_t *pte, pmd_t *pmd, unsigned int flags)
3348{
3349 pte_t entry;
3350 spinlock_t *ptl;
3351
3352 /*
3353 * some architectures can have larger ptes than wordsize,
3354 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and CONFIG_32BIT=y,
3355 * so READ_ONCE or ACCESS_ONCE cannot guarantee atomic accesses.
3356 * The code below just needs a consistent view for the ifs and
3357 * we later double check anyway with the ptl lock held. So here
3358 * a barrier will do.
3359 */
3360 entry = *pte;
3361 barrier();
3362 if (!pte_present(entry)) {
3363 if (pte_none(entry)) {
3364 if (vma_is_anonymous(vma))
3365 return do_anonymous_page(mm, vma, address,
3366 pte, pmd, flags);
3367 else
3368 return do_fault(mm, vma, address, pte, pmd,
3369 flags, entry);
3370 }
3371 return do_swap_page(mm, vma, address,
3372 pte, pmd, flags, entry);
3373 }
3374
3375 if (pte_protnone(entry))
3376 return do_numa_page(mm, vma, address, entry, pte, pmd);
3377
3378 ptl = pte_lockptr(mm, pmd);
3379 spin_lock(ptl);
3380 if (unlikely(!pte_same(*pte, entry)))
3381 goto unlock;
3382 if (flags & FAULT_FLAG_WRITE) {
3383 if (!pte_write(entry))
3384 return do_wp_page(mm, vma, address,
3385 pte, pmd, ptl, entry);
3386 entry = pte_mkdirty(entry);
3387 }
3388 entry = pte_mkyoung(entry);
3389 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3390 update_mmu_cache(vma, address, pte);
3391 } else {
3392 /*
3393 * This is needed only for protection faults but the arch code
3394 * is not yet telling us if this is a protection fault or not.
3395 * This still avoids useless tlb flushes for .text page faults
3396 * with threads.
3397 */
3398 if (flags & FAULT_FLAG_WRITE)
3399 flush_tlb_fix_spurious_fault(vma, address);
3400 }
3401unlock:
3402 pte_unmap_unlock(pte, ptl);
3403 return 0;
3404}
3405
3406/*
3407 * By the time we get here, we already hold the mm semaphore
3408 *
3409 * The mmap_sem may have been released depending on flags and our
3410 * return value. See filemap_fault() and __lock_page_or_retry().
3411 */
3412static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3413 unsigned long address, unsigned int flags)
3414{
3415 pgd_t *pgd;
3416 pud_t *pud;
3417 pmd_t *pmd;
3418 pte_t *pte;
3419
3420 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3421 flags & FAULT_FLAG_INSTRUCTION,
3422 flags & FAULT_FLAG_REMOTE))
3423 return VM_FAULT_SIGSEGV;
3424
3425 if (unlikely(is_vm_hugetlb_page(vma)))
3426 return hugetlb_fault(mm, vma, address, flags);
3427
3428 pgd = pgd_offset(mm, address);
3429 pud = pud_alloc(mm, pgd, address);
3430 if (!pud)
3431 return VM_FAULT_OOM;
3432 pmd = pmd_alloc(mm, pud, address);
3433 if (!pmd)
3434 return VM_FAULT_OOM;
3435 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3436 int ret = create_huge_pmd(mm, vma, address, pmd, flags);
3437 if (!(ret & VM_FAULT_FALLBACK))
3438 return ret;
3439 } else {
3440 pmd_t orig_pmd = *pmd;
3441 int ret;
3442
3443 barrier();
3444 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3445 unsigned int dirty = flags & FAULT_FLAG_WRITE;
3446
3447 if (pmd_protnone(orig_pmd))
3448 return do_huge_pmd_numa_page(mm, vma, address,
3449 orig_pmd, pmd);
3450
3451 if (dirty && !pmd_write(orig_pmd)) {
3452 ret = wp_huge_pmd(mm, vma, address, pmd,
3453 orig_pmd, flags);
3454 if (!(ret & VM_FAULT_FALLBACK))
3455 return ret;
3456 } else {
3457 huge_pmd_set_accessed(mm, vma, address, pmd,
3458 orig_pmd, dirty);
3459 return 0;
3460 }
3461 }
3462 }
3463
3464 /*
3465 * Use pte_alloc() instead of pte_alloc_map, because we can't
3466 * run pte_offset_map on the pmd, if an huge pmd could
3467 * materialize from under us from a different thread.
3468 */
3469 if (unlikely(pte_alloc(mm, pmd, address)))
3470 return VM_FAULT_OOM;
3471 /*
3472 * If a huge pmd materialized under us just retry later. Use
3473 * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
3474 * didn't become pmd_trans_huge under us and then back to pmd_none, as
3475 * a result of MADV_DONTNEED running immediately after a huge pmd fault
3476 * in a different thread of this mm, in turn leading to a misleading
3477 * pmd_trans_huge() retval. All we have to ensure is that it is a
3478 * regular pmd that we can walk with pte_offset_map() and we can do that
3479 * through an atomic read in C, which is what pmd_trans_unstable()
3480 * provides.
3481 */
3482 if (unlikely(pmd_trans_unstable(pmd) || pmd_devmap(*pmd)))
3483 return 0;
3484 /*
3485 * A regular pmd is established and it can't morph into a huge pmd
3486 * from under us anymore at this point because we hold the mmap_sem
3487 * read mode and khugepaged takes it in write mode. So now it's
3488 * safe to run pte_offset_map().
3489 */
3490 pte = pte_offset_map(pmd, address);
3491
3492 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3493}
3494
3495/*
3496 * By the time we get here, we already hold the mm semaphore
3497 *
3498 * The mmap_sem may have been released depending on flags and our
3499 * return value. See filemap_fault() and __lock_page_or_retry().
3500 */
3501int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3502 unsigned long address, unsigned int flags)
3503{
3504 int ret;
3505
3506 __set_current_state(TASK_RUNNING);
3507
3508 count_vm_event(PGFAULT);
3509 mem_cgroup_count_vm_event(mm, PGFAULT);
3510
3511 /* do counter updates before entering really critical section. */
3512 check_sync_rss_stat(current);
3513
3514 /*
3515 * Enable the memcg OOM handling for faults triggered in user
3516 * space. Kernel faults are handled more gracefully.
3517 */
3518 if (flags & FAULT_FLAG_USER)
3519 mem_cgroup_oom_enable();
3520
3521 ret = __handle_mm_fault(mm, vma, address, flags);
3522
3523 if (flags & FAULT_FLAG_USER) {
3524 mem_cgroup_oom_disable();
3525 /*
3526 * The task may have entered a memcg OOM situation but
3527 * if the allocation error was handled gracefully (no
3528 * VM_FAULT_OOM), there is no need to kill anything.
3529 * Just clean up the OOM state peacefully.
3530 */
3531 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3532 mem_cgroup_oom_synchronize(false);
3533 }
3534
3535 return ret;
3536}
3537EXPORT_SYMBOL_GPL(handle_mm_fault);
3538
3539#ifndef __PAGETABLE_PUD_FOLDED
3540/*
3541 * Allocate page upper directory.
3542 * We've already handled the fast-path in-line.
3543 */
3544int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3545{
3546 pud_t *new = pud_alloc_one(mm, address);
3547 if (!new)
3548 return -ENOMEM;
3549
3550 smp_wmb(); /* See comment in __pte_alloc */
3551
3552 spin_lock(&mm->page_table_lock);
3553 if (pgd_present(*pgd)) /* Another has populated it */
3554 pud_free(mm, new);
3555 else
3556 pgd_populate(mm, pgd, new);
3557 spin_unlock(&mm->page_table_lock);
3558 return 0;
3559}
3560#endif /* __PAGETABLE_PUD_FOLDED */
3561
3562#ifndef __PAGETABLE_PMD_FOLDED
3563/*
3564 * Allocate page middle directory.
3565 * We've already handled the fast-path in-line.
3566 */
3567int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3568{
3569 pmd_t *new = pmd_alloc_one(mm, address);
3570 if (!new)
3571 return -ENOMEM;
3572
3573 smp_wmb(); /* See comment in __pte_alloc */
3574
3575 spin_lock(&mm->page_table_lock);
3576#ifndef __ARCH_HAS_4LEVEL_HACK
3577 if (!pud_present(*pud)) {
3578 mm_inc_nr_pmds(mm);
3579 pud_populate(mm, pud, new);
3580 } else /* Another has populated it */
3581 pmd_free(mm, new);
3582#else
3583 if (!pgd_present(*pud)) {
3584 mm_inc_nr_pmds(mm);
3585 pgd_populate(mm, pud, new);
3586 } else /* Another has populated it */
3587 pmd_free(mm, new);
3588#endif /* __ARCH_HAS_4LEVEL_HACK */
3589 spin_unlock(&mm->page_table_lock);
3590 return 0;
3591}
3592#endif /* __PAGETABLE_PMD_FOLDED */
3593
3594static int __follow_pte(struct mm_struct *mm, unsigned long address,
3595 pte_t **ptepp, spinlock_t **ptlp)
3596{
3597 pgd_t *pgd;
3598 pud_t *pud;
3599 pmd_t *pmd;
3600 pte_t *ptep;
3601
3602 pgd = pgd_offset(mm, address);
3603 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3604 goto out;
3605
3606 pud = pud_offset(pgd, address);
3607 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3608 goto out;
3609
3610 pmd = pmd_offset(pud, address);
3611 VM_BUG_ON(pmd_trans_huge(*pmd));
3612 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3613 goto out;
3614
3615 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3616 if (pmd_huge(*pmd))
3617 goto out;
3618
3619 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3620 if (!ptep)
3621 goto out;
3622 if (!pte_present(*ptep))
3623 goto unlock;
3624 *ptepp = ptep;
3625 return 0;
3626unlock:
3627 pte_unmap_unlock(ptep, *ptlp);
3628out:
3629 return -EINVAL;
3630}
3631
3632static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3633 pte_t **ptepp, spinlock_t **ptlp)
3634{
3635 int res;
3636
3637 /* (void) is needed to make gcc happy */
3638 (void) __cond_lock(*ptlp,
3639 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3640 return res;
3641}
3642
3643/**
3644 * follow_pfn - look up PFN at a user virtual address
3645 * @vma: memory mapping
3646 * @address: user virtual address
3647 * @pfn: location to store found PFN
3648 *
3649 * Only IO mappings and raw PFN mappings are allowed.
3650 *
3651 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3652 */
3653int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3654 unsigned long *pfn)
3655{
3656 int ret = -EINVAL;
3657 spinlock_t *ptl;
3658 pte_t *ptep;
3659
3660 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3661 return ret;
3662
3663 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3664 if (ret)
3665 return ret;
3666 *pfn = pte_pfn(*ptep);
3667 pte_unmap_unlock(ptep, ptl);
3668 return 0;
3669}
3670EXPORT_SYMBOL(follow_pfn);
3671
3672#ifdef CONFIG_HAVE_IOREMAP_PROT
3673int follow_phys(struct vm_area_struct *vma,
3674 unsigned long address, unsigned int flags,
3675 unsigned long *prot, resource_size_t *phys)
3676{
3677 int ret = -EINVAL;
3678 pte_t *ptep, pte;
3679 spinlock_t *ptl;
3680
3681 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3682 goto out;
3683
3684 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3685 goto out;
3686 pte = *ptep;
3687
3688 if ((flags & FOLL_WRITE) && !pte_write(pte))
3689 goto unlock;
3690
3691 *prot = pgprot_val(pte_pgprot(pte));
3692 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3693
3694 ret = 0;
3695unlock:
3696 pte_unmap_unlock(ptep, ptl);
3697out:
3698 return ret;
3699}
3700
3701int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3702 void *buf, int len, int write)
3703{
3704 resource_size_t phys_addr;
3705 unsigned long prot = 0;
3706 void __iomem *maddr;
3707 int offset = addr & (PAGE_SIZE-1);
3708
3709 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3710 return -EINVAL;
3711
3712 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3713 if (write)
3714 memcpy_toio(maddr + offset, buf, len);
3715 else
3716 memcpy_fromio(buf, maddr + offset, len);
3717 iounmap(maddr);
3718
3719 return len;
3720}
3721EXPORT_SYMBOL_GPL(generic_access_phys);
3722#endif
3723
3724/*
3725 * Access another process' address space as given in mm. If non-NULL, use the
3726 * given task for page fault accounting.
3727 */
3728static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3729 unsigned long addr, void *buf, int len, int write)
3730{
3731 struct vm_area_struct *vma;
3732 void *old_buf = buf;
3733
3734 down_read(&mm->mmap_sem);
3735 /* ignore errors, just check how much was successfully transferred */
3736 while (len) {
3737 int bytes, ret, offset;
3738 void *maddr;
3739 struct page *page = NULL;
3740
3741 ret = get_user_pages_remote(tsk, mm, addr, 1,
3742 write, 1, &page, &vma);
3743 if (ret <= 0) {
3744#ifndef CONFIG_HAVE_IOREMAP_PROT
3745 break;
3746#else
3747 /*
3748 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3749 * we can access using slightly different code.
3750 */
3751 vma = find_vma(mm, addr);
3752 if (!vma || vma->vm_start > addr)
3753 break;
3754 if (vma->vm_ops && vma->vm_ops->access)
3755 ret = vma->vm_ops->access(vma, addr, buf,
3756 len, write);
3757 if (ret <= 0)
3758 break;
3759 bytes = ret;
3760#endif
3761 } else {
3762 bytes = len;
3763 offset = addr & (PAGE_SIZE-1);
3764 if (bytes > PAGE_SIZE-offset)
3765 bytes = PAGE_SIZE-offset;
3766
3767 maddr = kmap(page);
3768 if (write) {
3769 copy_to_user_page(vma, page, addr,
3770 maddr + offset, buf, bytes);
3771 set_page_dirty_lock(page);
3772 } else {
3773 copy_from_user_page(vma, page, addr,
3774 buf, maddr + offset, bytes);
3775 }
3776 kunmap(page);
3777 put_page(page);
3778 }
3779 len -= bytes;
3780 buf += bytes;
3781 addr += bytes;
3782 }
3783 up_read(&mm->mmap_sem);
3784
3785 return buf - old_buf;
3786}
3787
3788/**
3789 * access_remote_vm - access another process' address space
3790 * @mm: the mm_struct of the target address space
3791 * @addr: start address to access
3792 * @buf: source or destination buffer
3793 * @len: number of bytes to transfer
3794 * @write: whether the access is a write
3795 *
3796 * The caller must hold a reference on @mm.
3797 */
3798int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3799 void *buf, int len, int write)
3800{
3801 return __access_remote_vm(NULL, mm, addr, buf, len, write);
3802}
3803
3804/*
3805 * Access another process' address space.
3806 * Source/target buffer must be kernel space,
3807 * Do not walk the page table directly, use get_user_pages
3808 */
3809int access_process_vm(struct task_struct *tsk, unsigned long addr,
3810 void *buf, int len, int write)
3811{
3812 struct mm_struct *mm;
3813 int ret;
3814
3815 mm = get_task_mm(tsk);
3816 if (!mm)
3817 return 0;
3818
3819 ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3820 mmput(mm);
3821
3822 return ret;
3823}
3824
3825/*
3826 * Print the name of a VMA.
3827 */
3828void print_vma_addr(char *prefix, unsigned long ip)
3829{
3830 struct mm_struct *mm = current->mm;
3831 struct vm_area_struct *vma;
3832
3833 /*
3834 * Do not print if we are in atomic
3835 * contexts (in exception stacks, etc.):
3836 */
3837 if (preempt_count())
3838 return;
3839
3840 down_read(&mm->mmap_sem);
3841 vma = find_vma(mm, ip);
3842 if (vma && vma->vm_file) {
3843 struct file *f = vma->vm_file;
3844 char *buf = (char *)__get_free_page(GFP_KERNEL);
3845 if (buf) {
3846 char *p;
3847
3848 p = file_path(f, buf, PAGE_SIZE);
3849 if (IS_ERR(p))
3850 p = "?";
3851 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3852 vma->vm_start,
3853 vma->vm_end - vma->vm_start);
3854 free_page((unsigned long)buf);
3855 }
3856 }
3857 up_read(&mm->mmap_sem);
3858}
3859
3860#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3861void __might_fault(const char *file, int line)
3862{
3863 /*
3864 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3865 * holding the mmap_sem, this is safe because kernel memory doesn't
3866 * get paged out, therefore we'll never actually fault, and the
3867 * below annotations will generate false positives.
3868 */
3869 if (segment_eq(get_fs(), KERNEL_DS))
3870 return;
3871 if (pagefault_disabled())
3872 return;
3873 __might_sleep(file, line, 0);
3874#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3875 if (current->mm)
3876 might_lock_read(¤t->mm->mmap_sem);
3877#endif
3878}
3879EXPORT_SYMBOL(__might_fault);
3880#endif
3881
3882#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3883static void clear_gigantic_page(struct page *page,
3884 unsigned long addr,
3885 unsigned int pages_per_huge_page)
3886{
3887 int i;
3888 struct page *p = page;
3889
3890 might_sleep();
3891 for (i = 0; i < pages_per_huge_page;
3892 i++, p = mem_map_next(p, page, i)) {
3893 cond_resched();
3894 clear_user_highpage(p, addr + i * PAGE_SIZE);
3895 }
3896}
3897void clear_huge_page(struct page *page,
3898 unsigned long addr, unsigned int pages_per_huge_page)
3899{
3900 int i;
3901
3902 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3903 clear_gigantic_page(page, addr, pages_per_huge_page);
3904 return;
3905 }
3906
3907 might_sleep();
3908 for (i = 0; i < pages_per_huge_page; i++) {
3909 cond_resched();
3910 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3911 }
3912}
3913
3914static void copy_user_gigantic_page(struct page *dst, struct page *src,
3915 unsigned long addr,
3916 struct vm_area_struct *vma,
3917 unsigned int pages_per_huge_page)
3918{
3919 int i;
3920 struct page *dst_base = dst;
3921 struct page *src_base = src;
3922
3923 for (i = 0; i < pages_per_huge_page; ) {
3924 cond_resched();
3925 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3926
3927 i++;
3928 dst = mem_map_next(dst, dst_base, i);
3929 src = mem_map_next(src, src_base, i);
3930 }
3931}
3932
3933void copy_user_huge_page(struct page *dst, struct page *src,
3934 unsigned long addr, struct vm_area_struct *vma,
3935 unsigned int pages_per_huge_page)
3936{
3937 int i;
3938
3939 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3940 copy_user_gigantic_page(dst, src, addr, vma,
3941 pages_per_huge_page);
3942 return;
3943 }
3944
3945 might_sleep();
3946 for (i = 0; i < pages_per_huge_page; i++) {
3947 cond_resched();
3948 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3949 }
3950}
3951#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
3952
3953#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3954
3955static struct kmem_cache *page_ptl_cachep;
3956
3957void __init ptlock_cache_init(void)
3958{
3959 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
3960 SLAB_PANIC, NULL);
3961}
3962
3963bool ptlock_alloc(struct page *page)
3964{
3965 spinlock_t *ptl;
3966
3967 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3968 if (!ptl)
3969 return false;
3970 page->ptl = ptl;
3971 return true;
3972}
3973
3974void ptlock_free(struct page *page)
3975{
3976 kmem_cache_free(page_ptl_cachep, page->ptl);
3977}
3978#endif