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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/memory.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 */
7
8/*
9 * demand-loading started 01.12.91 - seems it is high on the list of
10 * things wanted, and it should be easy to implement. - Linus
11 */
12
13/*
14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 * pages started 02.12.91, seems to work. - Linus.
16 *
17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 * would have taken more than the 6M I have free, but it worked well as
19 * far as I could see.
20 *
21 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22 */
23
24/*
25 * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 * thought has to go into this. Oh, well..
27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 * Found it. Everything seems to work now.
29 * 20.12.91 - Ok, making the swap-device changeable like the root.
30 */
31
32/*
33 * 05.04.94 - Multi-page memory management added for v1.1.
34 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 *
36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 * (Gerhard.Wichert@pdb.siemens.de)
38 *
39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40 */
41
42#include <linux/kernel_stat.h>
43#include <linux/mm.h>
44#include <linux/mm_inline.h>
45#include <linux/sched/mm.h>
46#include <linux/sched/coredump.h>
47#include <linux/sched/numa_balancing.h>
48#include <linux/sched/task.h>
49#include <linux/hugetlb.h>
50#include <linux/mman.h>
51#include <linux/swap.h>
52#include <linux/highmem.h>
53#include <linux/pagemap.h>
54#include <linux/memremap.h>
55#include <linux/kmsan.h>
56#include <linux/ksm.h>
57#include <linux/rmap.h>
58#include <linux/export.h>
59#include <linux/delayacct.h>
60#include <linux/init.h>
61#include <linux/pfn_t.h>
62#include <linux/writeback.h>
63#include <linux/memcontrol.h>
64#include <linux/mmu_notifier.h>
65#include <linux/swapops.h>
66#include <linux/elf.h>
67#include <linux/gfp.h>
68#include <linux/migrate.h>
69#include <linux/string.h>
70#include <linux/memory-tiers.h>
71#include <linux/debugfs.h>
72#include <linux/userfaultfd_k.h>
73#include <linux/dax.h>
74#include <linux/oom.h>
75#include <linux/numa.h>
76#include <linux/perf_event.h>
77#include <linux/ptrace.h>
78#include <linux/vmalloc.h>
79#include <linux/sched/sysctl.h>
80
81#include <trace/events/kmem.h>
82
83#include <asm/io.h>
84#include <asm/mmu_context.h>
85#include <asm/pgalloc.h>
86#include <linux/uaccess.h>
87#include <asm/tlb.h>
88#include <asm/tlbflush.h>
89
90#include "pgalloc-track.h"
91#include "internal.h"
92#include "swap.h"
93
94#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
95#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
96#endif
97
98#ifndef CONFIG_NUMA
99unsigned long max_mapnr;
100EXPORT_SYMBOL(max_mapnr);
101
102struct page *mem_map;
103EXPORT_SYMBOL(mem_map);
104#endif
105
106static vm_fault_t do_fault(struct vm_fault *vmf);
107
108/*
109 * A number of key systems in x86 including ioremap() rely on the assumption
110 * that high_memory defines the upper bound on direct map memory, then end
111 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
112 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
113 * and ZONE_HIGHMEM.
114 */
115void *high_memory;
116EXPORT_SYMBOL(high_memory);
117
118/*
119 * Randomize the address space (stacks, mmaps, brk, etc.).
120 *
121 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
122 * as ancient (libc5 based) binaries can segfault. )
123 */
124int randomize_va_space __read_mostly =
125#ifdef CONFIG_COMPAT_BRK
126 1;
127#else
128 2;
129#endif
130
131#ifndef arch_wants_old_prefaulted_pte
132static inline bool arch_wants_old_prefaulted_pte(void)
133{
134 /*
135 * Transitioning a PTE from 'old' to 'young' can be expensive on
136 * some architectures, even if it's performed in hardware. By
137 * default, "false" means prefaulted entries will be 'young'.
138 */
139 return false;
140}
141#endif
142
143static int __init disable_randmaps(char *s)
144{
145 randomize_va_space = 0;
146 return 1;
147}
148__setup("norandmaps", disable_randmaps);
149
150unsigned long zero_pfn __read_mostly;
151EXPORT_SYMBOL(zero_pfn);
152
153unsigned long highest_memmap_pfn __read_mostly;
154
155/*
156 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
157 */
158static int __init init_zero_pfn(void)
159{
160 zero_pfn = page_to_pfn(ZERO_PAGE(0));
161 return 0;
162}
163early_initcall(init_zero_pfn);
164
165void mm_trace_rss_stat(struct mm_struct *mm, int member)
166{
167 trace_rss_stat(mm, member);
168}
169
170/*
171 * Note: this doesn't free the actual pages themselves. That
172 * has been handled earlier when unmapping all the memory regions.
173 */
174static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
175 unsigned long addr)
176{
177 pgtable_t token = pmd_pgtable(*pmd);
178 pmd_clear(pmd);
179 pte_free_tlb(tlb, token, addr);
180 mm_dec_nr_ptes(tlb->mm);
181}
182
183static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
184 unsigned long addr, unsigned long end,
185 unsigned long floor, unsigned long ceiling)
186{
187 pmd_t *pmd;
188 unsigned long next;
189 unsigned long start;
190
191 start = addr;
192 pmd = pmd_offset(pud, addr);
193 do {
194 next = pmd_addr_end(addr, end);
195 if (pmd_none_or_clear_bad(pmd))
196 continue;
197 free_pte_range(tlb, pmd, addr);
198 } while (pmd++, addr = next, addr != end);
199
200 start &= PUD_MASK;
201 if (start < floor)
202 return;
203 if (ceiling) {
204 ceiling &= PUD_MASK;
205 if (!ceiling)
206 return;
207 }
208 if (end - 1 > ceiling - 1)
209 return;
210
211 pmd = pmd_offset(pud, start);
212 pud_clear(pud);
213 pmd_free_tlb(tlb, pmd, start);
214 mm_dec_nr_pmds(tlb->mm);
215}
216
217static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
218 unsigned long addr, unsigned long end,
219 unsigned long floor, unsigned long ceiling)
220{
221 pud_t *pud;
222 unsigned long next;
223 unsigned long start;
224
225 start = addr;
226 pud = pud_offset(p4d, addr);
227 do {
228 next = pud_addr_end(addr, end);
229 if (pud_none_or_clear_bad(pud))
230 continue;
231 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
232 } while (pud++, addr = next, addr != end);
233
234 start &= P4D_MASK;
235 if (start < floor)
236 return;
237 if (ceiling) {
238 ceiling &= P4D_MASK;
239 if (!ceiling)
240 return;
241 }
242 if (end - 1 > ceiling - 1)
243 return;
244
245 pud = pud_offset(p4d, start);
246 p4d_clear(p4d);
247 pud_free_tlb(tlb, pud, start);
248 mm_dec_nr_puds(tlb->mm);
249}
250
251static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
252 unsigned long addr, unsigned long end,
253 unsigned long floor, unsigned long ceiling)
254{
255 p4d_t *p4d;
256 unsigned long next;
257 unsigned long start;
258
259 start = addr;
260 p4d = p4d_offset(pgd, addr);
261 do {
262 next = p4d_addr_end(addr, end);
263 if (p4d_none_or_clear_bad(p4d))
264 continue;
265 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
266 } while (p4d++, addr = next, addr != end);
267
268 start &= PGDIR_MASK;
269 if (start < floor)
270 return;
271 if (ceiling) {
272 ceiling &= PGDIR_MASK;
273 if (!ceiling)
274 return;
275 }
276 if (end - 1 > ceiling - 1)
277 return;
278
279 p4d = p4d_offset(pgd, start);
280 pgd_clear(pgd);
281 p4d_free_tlb(tlb, p4d, start);
282}
283
284/*
285 * This function frees user-level page tables of a process.
286 */
287void free_pgd_range(struct mmu_gather *tlb,
288 unsigned long addr, unsigned long end,
289 unsigned long floor, unsigned long ceiling)
290{
291 pgd_t *pgd;
292 unsigned long next;
293
294 /*
295 * The next few lines have given us lots of grief...
296 *
297 * Why are we testing PMD* at this top level? Because often
298 * there will be no work to do at all, and we'd prefer not to
299 * go all the way down to the bottom just to discover that.
300 *
301 * Why all these "- 1"s? Because 0 represents both the bottom
302 * of the address space and the top of it (using -1 for the
303 * top wouldn't help much: the masks would do the wrong thing).
304 * The rule is that addr 0 and floor 0 refer to the bottom of
305 * the address space, but end 0 and ceiling 0 refer to the top
306 * Comparisons need to use "end - 1" and "ceiling - 1" (though
307 * that end 0 case should be mythical).
308 *
309 * Wherever addr is brought up or ceiling brought down, we must
310 * be careful to reject "the opposite 0" before it confuses the
311 * subsequent tests. But what about where end is brought down
312 * by PMD_SIZE below? no, end can't go down to 0 there.
313 *
314 * Whereas we round start (addr) and ceiling down, by different
315 * masks at different levels, in order to test whether a table
316 * now has no other vmas using it, so can be freed, we don't
317 * bother to round floor or end up - the tests don't need that.
318 */
319
320 addr &= PMD_MASK;
321 if (addr < floor) {
322 addr += PMD_SIZE;
323 if (!addr)
324 return;
325 }
326 if (ceiling) {
327 ceiling &= PMD_MASK;
328 if (!ceiling)
329 return;
330 }
331 if (end - 1 > ceiling - 1)
332 end -= PMD_SIZE;
333 if (addr > end - 1)
334 return;
335 /*
336 * We add page table cache pages with PAGE_SIZE,
337 * (see pte_free_tlb()), flush the tlb if we need
338 */
339 tlb_change_page_size(tlb, PAGE_SIZE);
340 pgd = pgd_offset(tlb->mm, addr);
341 do {
342 next = pgd_addr_end(addr, end);
343 if (pgd_none_or_clear_bad(pgd))
344 continue;
345 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
346 } while (pgd++, addr = next, addr != end);
347}
348
349void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
350 struct vm_area_struct *vma, unsigned long floor,
351 unsigned long ceiling)
352{
353 MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
354
355 do {
356 unsigned long addr = vma->vm_start;
357 struct vm_area_struct *next;
358
359 /*
360 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
361 * be 0. This will underflow and is okay.
362 */
363 next = mas_find(&mas, ceiling - 1);
364
365 /*
366 * Hide vma from rmap and truncate_pagecache before freeing
367 * pgtables
368 */
369 unlink_anon_vmas(vma);
370 unlink_file_vma(vma);
371
372 if (is_vm_hugetlb_page(vma)) {
373 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
374 floor, next ? next->vm_start : ceiling);
375 } else {
376 /*
377 * Optimization: gather nearby vmas into one call down
378 */
379 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
380 && !is_vm_hugetlb_page(next)) {
381 vma = next;
382 next = mas_find(&mas, ceiling - 1);
383 unlink_anon_vmas(vma);
384 unlink_file_vma(vma);
385 }
386 free_pgd_range(tlb, addr, vma->vm_end,
387 floor, next ? next->vm_start : ceiling);
388 }
389 vma = next;
390 } while (vma);
391}
392
393void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
394{
395 spinlock_t *ptl = pmd_lock(mm, pmd);
396
397 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
398 mm_inc_nr_ptes(mm);
399 /*
400 * Ensure all pte setup (eg. pte page lock and page clearing) are
401 * visible before the pte is made visible to other CPUs by being
402 * put into page tables.
403 *
404 * The other side of the story is the pointer chasing in the page
405 * table walking code (when walking the page table without locking;
406 * ie. most of the time). Fortunately, these data accesses consist
407 * of a chain of data-dependent loads, meaning most CPUs (alpha
408 * being the notable exception) will already guarantee loads are
409 * seen in-order. See the alpha page table accessors for the
410 * smp_rmb() barriers in page table walking code.
411 */
412 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
413 pmd_populate(mm, pmd, *pte);
414 *pte = NULL;
415 }
416 spin_unlock(ptl);
417}
418
419int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
420{
421 pgtable_t new = pte_alloc_one(mm);
422 if (!new)
423 return -ENOMEM;
424
425 pmd_install(mm, pmd, &new);
426 if (new)
427 pte_free(mm, new);
428 return 0;
429}
430
431int __pte_alloc_kernel(pmd_t *pmd)
432{
433 pte_t *new = pte_alloc_one_kernel(&init_mm);
434 if (!new)
435 return -ENOMEM;
436
437 spin_lock(&init_mm.page_table_lock);
438 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
439 smp_wmb(); /* See comment in pmd_install() */
440 pmd_populate_kernel(&init_mm, pmd, new);
441 new = NULL;
442 }
443 spin_unlock(&init_mm.page_table_lock);
444 if (new)
445 pte_free_kernel(&init_mm, new);
446 return 0;
447}
448
449static inline void init_rss_vec(int *rss)
450{
451 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
452}
453
454static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
455{
456 int i;
457
458 if (current->mm == mm)
459 sync_mm_rss(mm);
460 for (i = 0; i < NR_MM_COUNTERS; i++)
461 if (rss[i])
462 add_mm_counter(mm, i, rss[i]);
463}
464
465/*
466 * This function is called to print an error when a bad pte
467 * is found. For example, we might have a PFN-mapped pte in
468 * a region that doesn't allow it.
469 *
470 * The calling function must still handle the error.
471 */
472static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
473 pte_t pte, struct page *page)
474{
475 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
476 p4d_t *p4d = p4d_offset(pgd, addr);
477 pud_t *pud = pud_offset(p4d, addr);
478 pmd_t *pmd = pmd_offset(pud, addr);
479 struct address_space *mapping;
480 pgoff_t index;
481 static unsigned long resume;
482 static unsigned long nr_shown;
483 static unsigned long nr_unshown;
484
485 /*
486 * Allow a burst of 60 reports, then keep quiet for that minute;
487 * or allow a steady drip of one report per second.
488 */
489 if (nr_shown == 60) {
490 if (time_before(jiffies, resume)) {
491 nr_unshown++;
492 return;
493 }
494 if (nr_unshown) {
495 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
496 nr_unshown);
497 nr_unshown = 0;
498 }
499 nr_shown = 0;
500 }
501 if (nr_shown++ == 0)
502 resume = jiffies + 60 * HZ;
503
504 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
505 index = linear_page_index(vma, addr);
506
507 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
508 current->comm,
509 (long long)pte_val(pte), (long long)pmd_val(*pmd));
510 if (page)
511 dump_page(page, "bad pte");
512 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
513 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
514 pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
515 vma->vm_file,
516 vma->vm_ops ? vma->vm_ops->fault : NULL,
517 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
518 mapping ? mapping->a_ops->read_folio : NULL);
519 dump_stack();
520 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
521}
522
523/*
524 * vm_normal_page -- This function gets the "struct page" associated with a pte.
525 *
526 * "Special" mappings do not wish to be associated with a "struct page" (either
527 * it doesn't exist, or it exists but they don't want to touch it). In this
528 * case, NULL is returned here. "Normal" mappings do have a struct page.
529 *
530 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
531 * pte bit, in which case this function is trivial. Secondly, an architecture
532 * may not have a spare pte bit, which requires a more complicated scheme,
533 * described below.
534 *
535 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
536 * special mapping (even if there are underlying and valid "struct pages").
537 * COWed pages of a VM_PFNMAP are always normal.
538 *
539 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
540 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
541 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
542 * mapping will always honor the rule
543 *
544 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
545 *
546 * And for normal mappings this is false.
547 *
548 * This restricts such mappings to be a linear translation from virtual address
549 * to pfn. To get around this restriction, we allow arbitrary mappings so long
550 * as the vma is not a COW mapping; in that case, we know that all ptes are
551 * special (because none can have been COWed).
552 *
553 *
554 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
555 *
556 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
557 * page" backing, however the difference is that _all_ pages with a struct
558 * page (that is, those where pfn_valid is true) are refcounted and considered
559 * normal pages by the VM. The disadvantage is that pages are refcounted
560 * (which can be slower and simply not an option for some PFNMAP users). The
561 * advantage is that we don't have to follow the strict linearity rule of
562 * PFNMAP mappings in order to support COWable mappings.
563 *
564 */
565struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
566 pte_t pte)
567{
568 unsigned long pfn = pte_pfn(pte);
569
570 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
571 if (likely(!pte_special(pte)))
572 goto check_pfn;
573 if (vma->vm_ops && vma->vm_ops->find_special_page)
574 return vma->vm_ops->find_special_page(vma, addr);
575 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
576 return NULL;
577 if (is_zero_pfn(pfn))
578 return NULL;
579 if (pte_devmap(pte))
580 /*
581 * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
582 * and will have refcounts incremented on their struct pages
583 * when they are inserted into PTEs, thus they are safe to
584 * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
585 * do not have refcounts. Example of legacy ZONE_DEVICE is
586 * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
587 */
588 return NULL;
589
590 print_bad_pte(vma, addr, pte, NULL);
591 return NULL;
592 }
593
594 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
595
596 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
597 if (vma->vm_flags & VM_MIXEDMAP) {
598 if (!pfn_valid(pfn))
599 return NULL;
600 goto out;
601 } else {
602 unsigned long off;
603 off = (addr - vma->vm_start) >> PAGE_SHIFT;
604 if (pfn == vma->vm_pgoff + off)
605 return NULL;
606 if (!is_cow_mapping(vma->vm_flags))
607 return NULL;
608 }
609 }
610
611 if (is_zero_pfn(pfn))
612 return NULL;
613
614check_pfn:
615 if (unlikely(pfn > highest_memmap_pfn)) {
616 print_bad_pte(vma, addr, pte, NULL);
617 return NULL;
618 }
619
620 /*
621 * NOTE! We still have PageReserved() pages in the page tables.
622 * eg. VDSO mappings can cause them to exist.
623 */
624out:
625 return pfn_to_page(pfn);
626}
627
628#ifdef CONFIG_TRANSPARENT_HUGEPAGE
629struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
630 pmd_t pmd)
631{
632 unsigned long pfn = pmd_pfn(pmd);
633
634 /*
635 * There is no pmd_special() but there may be special pmds, e.g.
636 * in a direct-access (dax) mapping, so let's just replicate the
637 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
638 */
639 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
640 if (vma->vm_flags & VM_MIXEDMAP) {
641 if (!pfn_valid(pfn))
642 return NULL;
643 goto out;
644 } else {
645 unsigned long off;
646 off = (addr - vma->vm_start) >> PAGE_SHIFT;
647 if (pfn == vma->vm_pgoff + off)
648 return NULL;
649 if (!is_cow_mapping(vma->vm_flags))
650 return NULL;
651 }
652 }
653
654 if (pmd_devmap(pmd))
655 return NULL;
656 if (is_huge_zero_pmd(pmd))
657 return NULL;
658 if (unlikely(pfn > highest_memmap_pfn))
659 return NULL;
660
661 /*
662 * NOTE! We still have PageReserved() pages in the page tables.
663 * eg. VDSO mappings can cause them to exist.
664 */
665out:
666 return pfn_to_page(pfn);
667}
668#endif
669
670static void restore_exclusive_pte(struct vm_area_struct *vma,
671 struct page *page, unsigned long address,
672 pte_t *ptep)
673{
674 pte_t pte;
675 swp_entry_t entry;
676
677 pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
678 if (pte_swp_soft_dirty(*ptep))
679 pte = pte_mksoft_dirty(pte);
680
681 entry = pte_to_swp_entry(*ptep);
682 if (pte_swp_uffd_wp(*ptep))
683 pte = pte_mkuffd_wp(pte);
684 else if (is_writable_device_exclusive_entry(entry))
685 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
686
687 VM_BUG_ON(pte_write(pte) && !(PageAnon(page) && PageAnonExclusive(page)));
688
689 /*
690 * No need to take a page reference as one was already
691 * created when the swap entry was made.
692 */
693 if (PageAnon(page))
694 page_add_anon_rmap(page, vma, address, RMAP_NONE);
695 else
696 /*
697 * Currently device exclusive access only supports anonymous
698 * memory so the entry shouldn't point to a filebacked page.
699 */
700 WARN_ON_ONCE(1);
701
702 set_pte_at(vma->vm_mm, address, ptep, pte);
703
704 /*
705 * No need to invalidate - it was non-present before. However
706 * secondary CPUs may have mappings that need invalidating.
707 */
708 update_mmu_cache(vma, address, ptep);
709}
710
711/*
712 * Tries to restore an exclusive pte if the page lock can be acquired without
713 * sleeping.
714 */
715static int
716try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
717 unsigned long addr)
718{
719 swp_entry_t entry = pte_to_swp_entry(*src_pte);
720 struct page *page = pfn_swap_entry_to_page(entry);
721
722 if (trylock_page(page)) {
723 restore_exclusive_pte(vma, page, addr, src_pte);
724 unlock_page(page);
725 return 0;
726 }
727
728 return -EBUSY;
729}
730
731/*
732 * copy one vm_area from one task to the other. Assumes the page tables
733 * already present in the new task to be cleared in the whole range
734 * covered by this vma.
735 */
736
737static unsigned long
738copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
739 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
740 struct vm_area_struct *src_vma, unsigned long addr, int *rss)
741{
742 unsigned long vm_flags = dst_vma->vm_flags;
743 pte_t pte = *src_pte;
744 struct page *page;
745 swp_entry_t entry = pte_to_swp_entry(pte);
746
747 if (likely(!non_swap_entry(entry))) {
748 if (swap_duplicate(entry) < 0)
749 return -EIO;
750
751 /* make sure dst_mm is on swapoff's mmlist. */
752 if (unlikely(list_empty(&dst_mm->mmlist))) {
753 spin_lock(&mmlist_lock);
754 if (list_empty(&dst_mm->mmlist))
755 list_add(&dst_mm->mmlist,
756 &src_mm->mmlist);
757 spin_unlock(&mmlist_lock);
758 }
759 /* Mark the swap entry as shared. */
760 if (pte_swp_exclusive(*src_pte)) {
761 pte = pte_swp_clear_exclusive(*src_pte);
762 set_pte_at(src_mm, addr, src_pte, pte);
763 }
764 rss[MM_SWAPENTS]++;
765 } else if (is_migration_entry(entry)) {
766 page = pfn_swap_entry_to_page(entry);
767
768 rss[mm_counter(page)]++;
769
770 if (!is_readable_migration_entry(entry) &&
771 is_cow_mapping(vm_flags)) {
772 /*
773 * COW mappings require pages in both parent and child
774 * to be set to read. A previously exclusive entry is
775 * now shared.
776 */
777 entry = make_readable_migration_entry(
778 swp_offset(entry));
779 pte = swp_entry_to_pte(entry);
780 if (pte_swp_soft_dirty(*src_pte))
781 pte = pte_swp_mksoft_dirty(pte);
782 if (pte_swp_uffd_wp(*src_pte))
783 pte = pte_swp_mkuffd_wp(pte);
784 set_pte_at(src_mm, addr, src_pte, pte);
785 }
786 } else if (is_device_private_entry(entry)) {
787 page = pfn_swap_entry_to_page(entry);
788
789 /*
790 * Update rss count even for unaddressable pages, as
791 * they should treated just like normal pages in this
792 * respect.
793 *
794 * We will likely want to have some new rss counters
795 * for unaddressable pages, at some point. But for now
796 * keep things as they are.
797 */
798 get_page(page);
799 rss[mm_counter(page)]++;
800 /* Cannot fail as these pages cannot get pinned. */
801 BUG_ON(page_try_dup_anon_rmap(page, false, src_vma));
802
803 /*
804 * We do not preserve soft-dirty information, because so
805 * far, checkpoint/restore is the only feature that
806 * requires that. And checkpoint/restore does not work
807 * when a device driver is involved (you cannot easily
808 * save and restore device driver state).
809 */
810 if (is_writable_device_private_entry(entry) &&
811 is_cow_mapping(vm_flags)) {
812 entry = make_readable_device_private_entry(
813 swp_offset(entry));
814 pte = swp_entry_to_pte(entry);
815 if (pte_swp_uffd_wp(*src_pte))
816 pte = pte_swp_mkuffd_wp(pte);
817 set_pte_at(src_mm, addr, src_pte, pte);
818 }
819 } else if (is_device_exclusive_entry(entry)) {
820 /*
821 * Make device exclusive entries present by restoring the
822 * original entry then copying as for a present pte. Device
823 * exclusive entries currently only support private writable
824 * (ie. COW) mappings.
825 */
826 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
827 if (try_restore_exclusive_pte(src_pte, src_vma, addr))
828 return -EBUSY;
829 return -ENOENT;
830 } else if (is_pte_marker_entry(entry)) {
831 if (is_swapin_error_entry(entry) || userfaultfd_wp(dst_vma))
832 set_pte_at(dst_mm, addr, dst_pte, pte);
833 return 0;
834 }
835 if (!userfaultfd_wp(dst_vma))
836 pte = pte_swp_clear_uffd_wp(pte);
837 set_pte_at(dst_mm, addr, dst_pte, pte);
838 return 0;
839}
840
841/*
842 * Copy a present and normal page.
843 *
844 * NOTE! The usual case is that this isn't required;
845 * instead, the caller can just increase the page refcount
846 * and re-use the pte the traditional way.
847 *
848 * And if we need a pre-allocated page but don't yet have
849 * one, return a negative error to let the preallocation
850 * code know so that it can do so outside the page table
851 * lock.
852 */
853static inline int
854copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
855 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
856 struct page **prealloc, struct page *page)
857{
858 struct page *new_page;
859 pte_t pte;
860
861 new_page = *prealloc;
862 if (!new_page)
863 return -EAGAIN;
864
865 /*
866 * We have a prealloc page, all good! Take it
867 * over and copy the page & arm it.
868 */
869 *prealloc = NULL;
870 copy_user_highpage(new_page, page, addr, src_vma);
871 __SetPageUptodate(new_page);
872 page_add_new_anon_rmap(new_page, dst_vma, addr);
873 lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
874 rss[mm_counter(new_page)]++;
875
876 /* All done, just insert the new page copy in the child */
877 pte = mk_pte(new_page, dst_vma->vm_page_prot);
878 pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
879 if (userfaultfd_pte_wp(dst_vma, *src_pte))
880 /* Uffd-wp needs to be delivered to dest pte as well */
881 pte = pte_wrprotect(pte_mkuffd_wp(pte));
882 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
883 return 0;
884}
885
886/*
887 * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
888 * is required to copy this pte.
889 */
890static inline int
891copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
892 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
893 struct page **prealloc)
894{
895 struct mm_struct *src_mm = src_vma->vm_mm;
896 unsigned long vm_flags = src_vma->vm_flags;
897 pte_t pte = *src_pte;
898 struct page *page;
899
900 page = vm_normal_page(src_vma, addr, pte);
901 if (page && PageAnon(page)) {
902 /*
903 * If this page may have been pinned by the parent process,
904 * copy the page immediately for the child so that we'll always
905 * guarantee the pinned page won't be randomly replaced in the
906 * future.
907 */
908 get_page(page);
909 if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) {
910 /* Page maybe pinned, we have to copy. */
911 put_page(page);
912 return copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
913 addr, rss, prealloc, page);
914 }
915 rss[mm_counter(page)]++;
916 } else if (page) {
917 get_page(page);
918 page_dup_file_rmap(page, false);
919 rss[mm_counter(page)]++;
920 }
921
922 /*
923 * If it's a COW mapping, write protect it both
924 * in the parent and the child
925 */
926 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
927 ptep_set_wrprotect(src_mm, addr, src_pte);
928 pte = pte_wrprotect(pte);
929 }
930 VM_BUG_ON(page && PageAnon(page) && PageAnonExclusive(page));
931
932 /*
933 * If it's a shared mapping, mark it clean in
934 * the child
935 */
936 if (vm_flags & VM_SHARED)
937 pte = pte_mkclean(pte);
938 pte = pte_mkold(pte);
939
940 if (!userfaultfd_wp(dst_vma))
941 pte = pte_clear_uffd_wp(pte);
942
943 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
944 return 0;
945}
946
947static inline struct page *
948page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
949 unsigned long addr)
950{
951 struct page *new_page;
952
953 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr);
954 if (!new_page)
955 return NULL;
956
957 if (mem_cgroup_charge(page_folio(new_page), src_mm, GFP_KERNEL)) {
958 put_page(new_page);
959 return NULL;
960 }
961 cgroup_throttle_swaprate(new_page, GFP_KERNEL);
962
963 return new_page;
964}
965
966static int
967copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
968 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
969 unsigned long end)
970{
971 struct mm_struct *dst_mm = dst_vma->vm_mm;
972 struct mm_struct *src_mm = src_vma->vm_mm;
973 pte_t *orig_src_pte, *orig_dst_pte;
974 pte_t *src_pte, *dst_pte;
975 spinlock_t *src_ptl, *dst_ptl;
976 int progress, ret = 0;
977 int rss[NR_MM_COUNTERS];
978 swp_entry_t entry = (swp_entry_t){0};
979 struct page *prealloc = NULL;
980
981again:
982 progress = 0;
983 init_rss_vec(rss);
984
985 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
986 if (!dst_pte) {
987 ret = -ENOMEM;
988 goto out;
989 }
990 src_pte = pte_offset_map(src_pmd, addr);
991 src_ptl = pte_lockptr(src_mm, src_pmd);
992 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
993 orig_src_pte = src_pte;
994 orig_dst_pte = dst_pte;
995 arch_enter_lazy_mmu_mode();
996
997 do {
998 /*
999 * We are holding two locks at this point - either of them
1000 * could generate latencies in another task on another CPU.
1001 */
1002 if (progress >= 32) {
1003 progress = 0;
1004 if (need_resched() ||
1005 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1006 break;
1007 }
1008 if (pte_none(*src_pte)) {
1009 progress++;
1010 continue;
1011 }
1012 if (unlikely(!pte_present(*src_pte))) {
1013 ret = copy_nonpresent_pte(dst_mm, src_mm,
1014 dst_pte, src_pte,
1015 dst_vma, src_vma,
1016 addr, rss);
1017 if (ret == -EIO) {
1018 entry = pte_to_swp_entry(*src_pte);
1019 break;
1020 } else if (ret == -EBUSY) {
1021 break;
1022 } else if (!ret) {
1023 progress += 8;
1024 continue;
1025 }
1026
1027 /*
1028 * Device exclusive entry restored, continue by copying
1029 * the now present pte.
1030 */
1031 WARN_ON_ONCE(ret != -ENOENT);
1032 }
1033 /* copy_present_pte() will clear `*prealloc' if consumed */
1034 ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
1035 addr, rss, &prealloc);
1036 /*
1037 * If we need a pre-allocated page for this pte, drop the
1038 * locks, allocate, and try again.
1039 */
1040 if (unlikely(ret == -EAGAIN))
1041 break;
1042 if (unlikely(prealloc)) {
1043 /*
1044 * pre-alloc page cannot be reused by next time so as
1045 * to strictly follow mempolicy (e.g., alloc_page_vma()
1046 * will allocate page according to address). This
1047 * could only happen if one pinned pte changed.
1048 */
1049 put_page(prealloc);
1050 prealloc = NULL;
1051 }
1052 progress += 8;
1053 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1054
1055 arch_leave_lazy_mmu_mode();
1056 spin_unlock(src_ptl);
1057 pte_unmap(orig_src_pte);
1058 add_mm_rss_vec(dst_mm, rss);
1059 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1060 cond_resched();
1061
1062 if (ret == -EIO) {
1063 VM_WARN_ON_ONCE(!entry.val);
1064 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1065 ret = -ENOMEM;
1066 goto out;
1067 }
1068 entry.val = 0;
1069 } else if (ret == -EBUSY) {
1070 goto out;
1071 } else if (ret == -EAGAIN) {
1072 prealloc = page_copy_prealloc(src_mm, src_vma, addr);
1073 if (!prealloc)
1074 return -ENOMEM;
1075 } else if (ret) {
1076 VM_WARN_ON_ONCE(1);
1077 }
1078
1079 /* We've captured and resolved the error. Reset, try again. */
1080 ret = 0;
1081
1082 if (addr != end)
1083 goto again;
1084out:
1085 if (unlikely(prealloc))
1086 put_page(prealloc);
1087 return ret;
1088}
1089
1090static inline int
1091copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1092 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1093 unsigned long end)
1094{
1095 struct mm_struct *dst_mm = dst_vma->vm_mm;
1096 struct mm_struct *src_mm = src_vma->vm_mm;
1097 pmd_t *src_pmd, *dst_pmd;
1098 unsigned long next;
1099
1100 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1101 if (!dst_pmd)
1102 return -ENOMEM;
1103 src_pmd = pmd_offset(src_pud, addr);
1104 do {
1105 next = pmd_addr_end(addr, end);
1106 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1107 || pmd_devmap(*src_pmd)) {
1108 int err;
1109 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1110 err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1111 addr, dst_vma, src_vma);
1112 if (err == -ENOMEM)
1113 return -ENOMEM;
1114 if (!err)
1115 continue;
1116 /* fall through */
1117 }
1118 if (pmd_none_or_clear_bad(src_pmd))
1119 continue;
1120 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1121 addr, next))
1122 return -ENOMEM;
1123 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1124 return 0;
1125}
1126
1127static inline int
1128copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1129 p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1130 unsigned long end)
1131{
1132 struct mm_struct *dst_mm = dst_vma->vm_mm;
1133 struct mm_struct *src_mm = src_vma->vm_mm;
1134 pud_t *src_pud, *dst_pud;
1135 unsigned long next;
1136
1137 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1138 if (!dst_pud)
1139 return -ENOMEM;
1140 src_pud = pud_offset(src_p4d, addr);
1141 do {
1142 next = pud_addr_end(addr, end);
1143 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1144 int err;
1145
1146 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1147 err = copy_huge_pud(dst_mm, src_mm,
1148 dst_pud, src_pud, addr, src_vma);
1149 if (err == -ENOMEM)
1150 return -ENOMEM;
1151 if (!err)
1152 continue;
1153 /* fall through */
1154 }
1155 if (pud_none_or_clear_bad(src_pud))
1156 continue;
1157 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1158 addr, next))
1159 return -ENOMEM;
1160 } while (dst_pud++, src_pud++, addr = next, addr != end);
1161 return 0;
1162}
1163
1164static inline int
1165copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1166 pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1167 unsigned long end)
1168{
1169 struct mm_struct *dst_mm = dst_vma->vm_mm;
1170 p4d_t *src_p4d, *dst_p4d;
1171 unsigned long next;
1172
1173 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1174 if (!dst_p4d)
1175 return -ENOMEM;
1176 src_p4d = p4d_offset(src_pgd, addr);
1177 do {
1178 next = p4d_addr_end(addr, end);
1179 if (p4d_none_or_clear_bad(src_p4d))
1180 continue;
1181 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1182 addr, next))
1183 return -ENOMEM;
1184 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1185 return 0;
1186}
1187
1188/*
1189 * Return true if the vma needs to copy the pgtable during this fork(). Return
1190 * false when we can speed up fork() by allowing lazy page faults later until
1191 * when the child accesses the memory range.
1192 */
1193static bool
1194vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1195{
1196 /*
1197 * Always copy pgtables when dst_vma has uffd-wp enabled even if it's
1198 * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable
1199 * contains uffd-wp protection information, that's something we can't
1200 * retrieve from page cache, and skip copying will lose those info.
1201 */
1202 if (userfaultfd_wp(dst_vma))
1203 return true;
1204
1205 if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
1206 return true;
1207
1208 if (src_vma->anon_vma)
1209 return true;
1210
1211 /*
1212 * Don't copy ptes where a page fault will fill them correctly. Fork
1213 * becomes much lighter when there are big shared or private readonly
1214 * mappings. The tradeoff is that copy_page_range is more efficient
1215 * than faulting.
1216 */
1217 return false;
1218}
1219
1220int
1221copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1222{
1223 pgd_t *src_pgd, *dst_pgd;
1224 unsigned long next;
1225 unsigned long addr = src_vma->vm_start;
1226 unsigned long end = src_vma->vm_end;
1227 struct mm_struct *dst_mm = dst_vma->vm_mm;
1228 struct mm_struct *src_mm = src_vma->vm_mm;
1229 struct mmu_notifier_range range;
1230 bool is_cow;
1231 int ret;
1232
1233 if (!vma_needs_copy(dst_vma, src_vma))
1234 return 0;
1235
1236 if (is_vm_hugetlb_page(src_vma))
1237 return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma);
1238
1239 if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1240 /*
1241 * We do not free on error cases below as remove_vma
1242 * gets called on error from higher level routine
1243 */
1244 ret = track_pfn_copy(src_vma);
1245 if (ret)
1246 return ret;
1247 }
1248
1249 /*
1250 * We need to invalidate the secondary MMU mappings only when
1251 * there could be a permission downgrade on the ptes of the
1252 * parent mm. And a permission downgrade will only happen if
1253 * is_cow_mapping() returns true.
1254 */
1255 is_cow = is_cow_mapping(src_vma->vm_flags);
1256
1257 if (is_cow) {
1258 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1259 0, src_vma, src_mm, addr, end);
1260 mmu_notifier_invalidate_range_start(&range);
1261 /*
1262 * Disabling preemption is not needed for the write side, as
1263 * the read side doesn't spin, but goes to the mmap_lock.
1264 *
1265 * Use the raw variant of the seqcount_t write API to avoid
1266 * lockdep complaining about preemptibility.
1267 */
1268 mmap_assert_write_locked(src_mm);
1269 raw_write_seqcount_begin(&src_mm->write_protect_seq);
1270 }
1271
1272 ret = 0;
1273 dst_pgd = pgd_offset(dst_mm, addr);
1274 src_pgd = pgd_offset(src_mm, addr);
1275 do {
1276 next = pgd_addr_end(addr, end);
1277 if (pgd_none_or_clear_bad(src_pgd))
1278 continue;
1279 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1280 addr, next))) {
1281 ret = -ENOMEM;
1282 break;
1283 }
1284 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1285
1286 if (is_cow) {
1287 raw_write_seqcount_end(&src_mm->write_protect_seq);
1288 mmu_notifier_invalidate_range_end(&range);
1289 }
1290 return ret;
1291}
1292
1293/* Whether we should zap all COWed (private) pages too */
1294static inline bool should_zap_cows(struct zap_details *details)
1295{
1296 /* By default, zap all pages */
1297 if (!details)
1298 return true;
1299
1300 /* Or, we zap COWed pages only if the caller wants to */
1301 return details->even_cows;
1302}
1303
1304/* Decides whether we should zap this page with the page pointer specified */
1305static inline bool should_zap_page(struct zap_details *details, struct page *page)
1306{
1307 /* If we can make a decision without *page.. */
1308 if (should_zap_cows(details))
1309 return true;
1310
1311 /* E.g. the caller passes NULL for the case of a zero page */
1312 if (!page)
1313 return true;
1314
1315 /* Otherwise we should only zap non-anon pages */
1316 return !PageAnon(page);
1317}
1318
1319static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
1320{
1321 if (!details)
1322 return false;
1323
1324 return details->zap_flags & ZAP_FLAG_DROP_MARKER;
1325}
1326
1327/*
1328 * This function makes sure that we'll replace the none pte with an uffd-wp
1329 * swap special pte marker when necessary. Must be with the pgtable lock held.
1330 */
1331static inline void
1332zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
1333 unsigned long addr, pte_t *pte,
1334 struct zap_details *details, pte_t pteval)
1335{
1336 if (zap_drop_file_uffd_wp(details))
1337 return;
1338
1339 pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
1340}
1341
1342static unsigned long zap_pte_range(struct mmu_gather *tlb,
1343 struct vm_area_struct *vma, pmd_t *pmd,
1344 unsigned long addr, unsigned long end,
1345 struct zap_details *details)
1346{
1347 struct mm_struct *mm = tlb->mm;
1348 int force_flush = 0;
1349 int rss[NR_MM_COUNTERS];
1350 spinlock_t *ptl;
1351 pte_t *start_pte;
1352 pte_t *pte;
1353 swp_entry_t entry;
1354
1355 tlb_change_page_size(tlb, PAGE_SIZE);
1356again:
1357 init_rss_vec(rss);
1358 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1359 pte = start_pte;
1360 flush_tlb_batched_pending(mm);
1361 arch_enter_lazy_mmu_mode();
1362 do {
1363 pte_t ptent = *pte;
1364 struct page *page;
1365
1366 if (pte_none(ptent))
1367 continue;
1368
1369 if (need_resched())
1370 break;
1371
1372 if (pte_present(ptent)) {
1373 unsigned int delay_rmap;
1374
1375 page = vm_normal_page(vma, addr, ptent);
1376 if (unlikely(!should_zap_page(details, page)))
1377 continue;
1378 ptent = ptep_get_and_clear_full(mm, addr, pte,
1379 tlb->fullmm);
1380 tlb_remove_tlb_entry(tlb, pte, addr);
1381 zap_install_uffd_wp_if_needed(vma, addr, pte, details,
1382 ptent);
1383 if (unlikely(!page))
1384 continue;
1385
1386 delay_rmap = 0;
1387 if (!PageAnon(page)) {
1388 if (pte_dirty(ptent)) {
1389 set_page_dirty(page);
1390 if (tlb_delay_rmap(tlb)) {
1391 delay_rmap = 1;
1392 force_flush = 1;
1393 }
1394 }
1395 if (pte_young(ptent) &&
1396 likely(!(vma->vm_flags & VM_SEQ_READ)))
1397 mark_page_accessed(page);
1398 }
1399 rss[mm_counter(page)]--;
1400 if (!delay_rmap) {
1401 page_remove_rmap(page, vma, false);
1402 if (unlikely(page_mapcount(page) < 0))
1403 print_bad_pte(vma, addr, ptent, page);
1404 }
1405 if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) {
1406 force_flush = 1;
1407 addr += PAGE_SIZE;
1408 break;
1409 }
1410 continue;
1411 }
1412
1413 entry = pte_to_swp_entry(ptent);
1414 if (is_device_private_entry(entry) ||
1415 is_device_exclusive_entry(entry)) {
1416 page = pfn_swap_entry_to_page(entry);
1417 if (unlikely(!should_zap_page(details, page)))
1418 continue;
1419 /*
1420 * Both device private/exclusive mappings should only
1421 * work with anonymous page so far, so we don't need to
1422 * consider uffd-wp bit when zap. For more information,
1423 * see zap_install_uffd_wp_if_needed().
1424 */
1425 WARN_ON_ONCE(!vma_is_anonymous(vma));
1426 rss[mm_counter(page)]--;
1427 if (is_device_private_entry(entry))
1428 page_remove_rmap(page, vma, false);
1429 put_page(page);
1430 } else if (!non_swap_entry(entry)) {
1431 /* Genuine swap entry, hence a private anon page */
1432 if (!should_zap_cows(details))
1433 continue;
1434 rss[MM_SWAPENTS]--;
1435 if (unlikely(!free_swap_and_cache(entry)))
1436 print_bad_pte(vma, addr, ptent, NULL);
1437 } else if (is_migration_entry(entry)) {
1438 page = pfn_swap_entry_to_page(entry);
1439 if (!should_zap_page(details, page))
1440 continue;
1441 rss[mm_counter(page)]--;
1442 } else if (pte_marker_entry_uffd_wp(entry)) {
1443 /* Only drop the uffd-wp marker if explicitly requested */
1444 if (!zap_drop_file_uffd_wp(details))
1445 continue;
1446 } else if (is_hwpoison_entry(entry) ||
1447 is_swapin_error_entry(entry)) {
1448 if (!should_zap_cows(details))
1449 continue;
1450 } else {
1451 /* We should have covered all the swap entry types */
1452 WARN_ON_ONCE(1);
1453 }
1454 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1455 zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent);
1456 } while (pte++, addr += PAGE_SIZE, addr != end);
1457
1458 add_mm_rss_vec(mm, rss);
1459 arch_leave_lazy_mmu_mode();
1460
1461 /* Do the actual TLB flush before dropping ptl */
1462 if (force_flush) {
1463 tlb_flush_mmu_tlbonly(tlb);
1464 tlb_flush_rmaps(tlb, vma);
1465 }
1466 pte_unmap_unlock(start_pte, ptl);
1467
1468 /*
1469 * If we forced a TLB flush (either due to running out of
1470 * batch buffers or because we needed to flush dirty TLB
1471 * entries before releasing the ptl), free the batched
1472 * memory too. Restart if we didn't do everything.
1473 */
1474 if (force_flush) {
1475 force_flush = 0;
1476 tlb_flush_mmu(tlb);
1477 }
1478
1479 if (addr != end) {
1480 cond_resched();
1481 goto again;
1482 }
1483
1484 return addr;
1485}
1486
1487static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1488 struct vm_area_struct *vma, pud_t *pud,
1489 unsigned long addr, unsigned long end,
1490 struct zap_details *details)
1491{
1492 pmd_t *pmd;
1493 unsigned long next;
1494
1495 pmd = pmd_offset(pud, addr);
1496 do {
1497 next = pmd_addr_end(addr, end);
1498 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1499 if (next - addr != HPAGE_PMD_SIZE)
1500 __split_huge_pmd(vma, pmd, addr, false, NULL);
1501 else if (zap_huge_pmd(tlb, vma, pmd, addr))
1502 goto next;
1503 /* fall through */
1504 } else if (details && details->single_folio &&
1505 folio_test_pmd_mappable(details->single_folio) &&
1506 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1507 spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1508 /*
1509 * Take and drop THP pmd lock so that we cannot return
1510 * prematurely, while zap_huge_pmd() has cleared *pmd,
1511 * but not yet decremented compound_mapcount().
1512 */
1513 spin_unlock(ptl);
1514 }
1515
1516 /*
1517 * Here there can be other concurrent MADV_DONTNEED or
1518 * trans huge page faults running, and if the pmd is
1519 * none or trans huge it can change under us. This is
1520 * because MADV_DONTNEED holds the mmap_lock in read
1521 * mode.
1522 */
1523 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1524 goto next;
1525 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1526next:
1527 cond_resched();
1528 } while (pmd++, addr = next, addr != end);
1529
1530 return addr;
1531}
1532
1533static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1534 struct vm_area_struct *vma, p4d_t *p4d,
1535 unsigned long addr, unsigned long end,
1536 struct zap_details *details)
1537{
1538 pud_t *pud;
1539 unsigned long next;
1540
1541 pud = pud_offset(p4d, addr);
1542 do {
1543 next = pud_addr_end(addr, end);
1544 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1545 if (next - addr != HPAGE_PUD_SIZE) {
1546 mmap_assert_locked(tlb->mm);
1547 split_huge_pud(vma, pud, addr);
1548 } else if (zap_huge_pud(tlb, vma, pud, addr))
1549 goto next;
1550 /* fall through */
1551 }
1552 if (pud_none_or_clear_bad(pud))
1553 continue;
1554 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1555next:
1556 cond_resched();
1557 } while (pud++, addr = next, addr != end);
1558
1559 return addr;
1560}
1561
1562static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1563 struct vm_area_struct *vma, pgd_t *pgd,
1564 unsigned long addr, unsigned long end,
1565 struct zap_details *details)
1566{
1567 p4d_t *p4d;
1568 unsigned long next;
1569
1570 p4d = p4d_offset(pgd, addr);
1571 do {
1572 next = p4d_addr_end(addr, end);
1573 if (p4d_none_or_clear_bad(p4d))
1574 continue;
1575 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1576 } while (p4d++, addr = next, addr != end);
1577
1578 return addr;
1579}
1580
1581void unmap_page_range(struct mmu_gather *tlb,
1582 struct vm_area_struct *vma,
1583 unsigned long addr, unsigned long end,
1584 struct zap_details *details)
1585{
1586 pgd_t *pgd;
1587 unsigned long next;
1588
1589 BUG_ON(addr >= end);
1590 tlb_start_vma(tlb, vma);
1591 pgd = pgd_offset(vma->vm_mm, addr);
1592 do {
1593 next = pgd_addr_end(addr, end);
1594 if (pgd_none_or_clear_bad(pgd))
1595 continue;
1596 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1597 } while (pgd++, addr = next, addr != end);
1598 tlb_end_vma(tlb, vma);
1599}
1600
1601
1602static void unmap_single_vma(struct mmu_gather *tlb,
1603 struct vm_area_struct *vma, unsigned long start_addr,
1604 unsigned long end_addr,
1605 struct zap_details *details)
1606{
1607 unsigned long start = max(vma->vm_start, start_addr);
1608 unsigned long end;
1609
1610 if (start >= vma->vm_end)
1611 return;
1612 end = min(vma->vm_end, end_addr);
1613 if (end <= vma->vm_start)
1614 return;
1615
1616 if (vma->vm_file)
1617 uprobe_munmap(vma, start, end);
1618
1619 if (unlikely(vma->vm_flags & VM_PFNMAP))
1620 untrack_pfn(vma, 0, 0);
1621
1622 if (start != end) {
1623 if (unlikely(is_vm_hugetlb_page(vma))) {
1624 /*
1625 * It is undesirable to test vma->vm_file as it
1626 * should be non-null for valid hugetlb area.
1627 * However, vm_file will be NULL in the error
1628 * cleanup path of mmap_region. When
1629 * hugetlbfs ->mmap method fails,
1630 * mmap_region() nullifies vma->vm_file
1631 * before calling this function to clean up.
1632 * Since no pte has actually been setup, it is
1633 * safe to do nothing in this case.
1634 */
1635 if (vma->vm_file) {
1636 zap_flags_t zap_flags = details ?
1637 details->zap_flags : 0;
1638 __unmap_hugepage_range_final(tlb, vma, start, end,
1639 NULL, zap_flags);
1640 }
1641 } else
1642 unmap_page_range(tlb, vma, start, end, details);
1643 }
1644}
1645
1646/**
1647 * unmap_vmas - unmap a range of memory covered by a list of vma's
1648 * @tlb: address of the caller's struct mmu_gather
1649 * @mt: the maple tree
1650 * @vma: the starting vma
1651 * @start_addr: virtual address at which to start unmapping
1652 * @end_addr: virtual address at which to end unmapping
1653 *
1654 * Unmap all pages in the vma list.
1655 *
1656 * Only addresses between `start' and `end' will be unmapped.
1657 *
1658 * The VMA list must be sorted in ascending virtual address order.
1659 *
1660 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1661 * range after unmap_vmas() returns. So the only responsibility here is to
1662 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1663 * drops the lock and schedules.
1664 */
1665void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
1666 struct vm_area_struct *vma, unsigned long start_addr,
1667 unsigned long end_addr)
1668{
1669 struct mmu_notifier_range range;
1670 struct zap_details details = {
1671 .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP,
1672 /* Careful - we need to zap private pages too! */
1673 .even_cows = true,
1674 };
1675 MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
1676
1677 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1678 start_addr, end_addr);
1679 mmu_notifier_invalidate_range_start(&range);
1680 do {
1681 unmap_single_vma(tlb, vma, start_addr, end_addr, &details);
1682 } while ((vma = mas_find(&mas, end_addr - 1)) != NULL);
1683 mmu_notifier_invalidate_range_end(&range);
1684}
1685
1686/**
1687 * zap_page_range - remove user pages in a given range
1688 * @vma: vm_area_struct holding the applicable pages
1689 * @start: starting address of pages to zap
1690 * @size: number of bytes to zap
1691 *
1692 * Caller must protect the VMA list
1693 */
1694void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1695 unsigned long size)
1696{
1697 struct maple_tree *mt = &vma->vm_mm->mm_mt;
1698 unsigned long end = start + size;
1699 struct mmu_notifier_range range;
1700 struct mmu_gather tlb;
1701 MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
1702
1703 lru_add_drain();
1704 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1705 start, start + size);
1706 tlb_gather_mmu(&tlb, vma->vm_mm);
1707 update_hiwater_rss(vma->vm_mm);
1708 mmu_notifier_invalidate_range_start(&range);
1709 do {
1710 unmap_single_vma(&tlb, vma, start, range.end, NULL);
1711 } while ((vma = mas_find(&mas, end - 1)) != NULL);
1712 mmu_notifier_invalidate_range_end(&range);
1713 tlb_finish_mmu(&tlb);
1714}
1715
1716/**
1717 * zap_page_range_single - remove user pages in a given range
1718 * @vma: vm_area_struct holding the applicable pages
1719 * @address: starting address of pages to zap
1720 * @size: number of bytes to zap
1721 * @details: details of shared cache invalidation
1722 *
1723 * The range must fit into one VMA.
1724 */
1725void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1726 unsigned long size, struct zap_details *details)
1727{
1728 const unsigned long end = address + size;
1729 struct mmu_notifier_range range;
1730 struct mmu_gather tlb;
1731
1732 lru_add_drain();
1733 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1734 address, end);
1735 if (is_vm_hugetlb_page(vma))
1736 adjust_range_if_pmd_sharing_possible(vma, &range.start,
1737 &range.end);
1738 tlb_gather_mmu(&tlb, vma->vm_mm);
1739 update_hiwater_rss(vma->vm_mm);
1740 mmu_notifier_invalidate_range_start(&range);
1741 /*
1742 * unmap 'address-end' not 'range.start-range.end' as range
1743 * could have been expanded for hugetlb pmd sharing.
1744 */
1745 unmap_single_vma(&tlb, vma, address, end, details);
1746 mmu_notifier_invalidate_range_end(&range);
1747 tlb_finish_mmu(&tlb);
1748}
1749
1750/**
1751 * zap_vma_ptes - remove ptes mapping the vma
1752 * @vma: vm_area_struct holding ptes to be zapped
1753 * @address: starting address of pages to zap
1754 * @size: number of bytes to zap
1755 *
1756 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1757 *
1758 * The entire address range must be fully contained within the vma.
1759 *
1760 */
1761void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1762 unsigned long size)
1763{
1764 if (!range_in_vma(vma, address, address + size) ||
1765 !(vma->vm_flags & VM_PFNMAP))
1766 return;
1767
1768 zap_page_range_single(vma, address, size, NULL);
1769}
1770EXPORT_SYMBOL_GPL(zap_vma_ptes);
1771
1772static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1773{
1774 pgd_t *pgd;
1775 p4d_t *p4d;
1776 pud_t *pud;
1777 pmd_t *pmd;
1778
1779 pgd = pgd_offset(mm, addr);
1780 p4d = p4d_alloc(mm, pgd, addr);
1781 if (!p4d)
1782 return NULL;
1783 pud = pud_alloc(mm, p4d, addr);
1784 if (!pud)
1785 return NULL;
1786 pmd = pmd_alloc(mm, pud, addr);
1787 if (!pmd)
1788 return NULL;
1789
1790 VM_BUG_ON(pmd_trans_huge(*pmd));
1791 return pmd;
1792}
1793
1794pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1795 spinlock_t **ptl)
1796{
1797 pmd_t *pmd = walk_to_pmd(mm, addr);
1798
1799 if (!pmd)
1800 return NULL;
1801 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1802}
1803
1804static int validate_page_before_insert(struct page *page)
1805{
1806 if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1807 return -EINVAL;
1808 flush_dcache_page(page);
1809 return 0;
1810}
1811
1812static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
1813 unsigned long addr, struct page *page, pgprot_t prot)
1814{
1815 if (!pte_none(*pte))
1816 return -EBUSY;
1817 /* Ok, finally just insert the thing.. */
1818 get_page(page);
1819 inc_mm_counter(vma->vm_mm, mm_counter_file(page));
1820 page_add_file_rmap(page, vma, false);
1821 set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
1822 return 0;
1823}
1824
1825/*
1826 * This is the old fallback for page remapping.
1827 *
1828 * For historical reasons, it only allows reserved pages. Only
1829 * old drivers should use this, and they needed to mark their
1830 * pages reserved for the old functions anyway.
1831 */
1832static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1833 struct page *page, pgprot_t prot)
1834{
1835 int retval;
1836 pte_t *pte;
1837 spinlock_t *ptl;
1838
1839 retval = validate_page_before_insert(page);
1840 if (retval)
1841 goto out;
1842 retval = -ENOMEM;
1843 pte = get_locked_pte(vma->vm_mm, addr, &ptl);
1844 if (!pte)
1845 goto out;
1846 retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
1847 pte_unmap_unlock(pte, ptl);
1848out:
1849 return retval;
1850}
1851
1852#ifdef pte_index
1853static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
1854 unsigned long addr, struct page *page, pgprot_t prot)
1855{
1856 int err;
1857
1858 if (!page_count(page))
1859 return -EINVAL;
1860 err = validate_page_before_insert(page);
1861 if (err)
1862 return err;
1863 return insert_page_into_pte_locked(vma, pte, addr, page, prot);
1864}
1865
1866/* insert_pages() amortizes the cost of spinlock operations
1867 * when inserting pages in a loop. Arch *must* define pte_index.
1868 */
1869static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
1870 struct page **pages, unsigned long *num, pgprot_t prot)
1871{
1872 pmd_t *pmd = NULL;
1873 pte_t *start_pte, *pte;
1874 spinlock_t *pte_lock;
1875 struct mm_struct *const mm = vma->vm_mm;
1876 unsigned long curr_page_idx = 0;
1877 unsigned long remaining_pages_total = *num;
1878 unsigned long pages_to_write_in_pmd;
1879 int ret;
1880more:
1881 ret = -EFAULT;
1882 pmd = walk_to_pmd(mm, addr);
1883 if (!pmd)
1884 goto out;
1885
1886 pages_to_write_in_pmd = min_t(unsigned long,
1887 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
1888
1889 /* Allocate the PTE if necessary; takes PMD lock once only. */
1890 ret = -ENOMEM;
1891 if (pte_alloc(mm, pmd))
1892 goto out;
1893
1894 while (pages_to_write_in_pmd) {
1895 int pte_idx = 0;
1896 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
1897
1898 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
1899 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
1900 int err = insert_page_in_batch_locked(vma, pte,
1901 addr, pages[curr_page_idx], prot);
1902 if (unlikely(err)) {
1903 pte_unmap_unlock(start_pte, pte_lock);
1904 ret = err;
1905 remaining_pages_total -= pte_idx;
1906 goto out;
1907 }
1908 addr += PAGE_SIZE;
1909 ++curr_page_idx;
1910 }
1911 pte_unmap_unlock(start_pte, pte_lock);
1912 pages_to_write_in_pmd -= batch_size;
1913 remaining_pages_total -= batch_size;
1914 }
1915 if (remaining_pages_total)
1916 goto more;
1917 ret = 0;
1918out:
1919 *num = remaining_pages_total;
1920 return ret;
1921}
1922#endif /* ifdef pte_index */
1923
1924/**
1925 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1926 * @vma: user vma to map to
1927 * @addr: target start user address of these pages
1928 * @pages: source kernel pages
1929 * @num: in: number of pages to map. out: number of pages that were *not*
1930 * mapped. (0 means all pages were successfully mapped).
1931 *
1932 * Preferred over vm_insert_page() when inserting multiple pages.
1933 *
1934 * In case of error, we may have mapped a subset of the provided
1935 * pages. It is the caller's responsibility to account for this case.
1936 *
1937 * The same restrictions apply as in vm_insert_page().
1938 */
1939int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
1940 struct page **pages, unsigned long *num)
1941{
1942#ifdef pte_index
1943 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
1944
1945 if (addr < vma->vm_start || end_addr >= vma->vm_end)
1946 return -EFAULT;
1947 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1948 BUG_ON(mmap_read_trylock(vma->vm_mm));
1949 BUG_ON(vma->vm_flags & VM_PFNMAP);
1950 vma->vm_flags |= VM_MIXEDMAP;
1951 }
1952 /* Defer page refcount checking till we're about to map that page. */
1953 return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
1954#else
1955 unsigned long idx = 0, pgcount = *num;
1956 int err = -EINVAL;
1957
1958 for (; idx < pgcount; ++idx) {
1959 err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
1960 if (err)
1961 break;
1962 }
1963 *num = pgcount - idx;
1964 return err;
1965#endif /* ifdef pte_index */
1966}
1967EXPORT_SYMBOL(vm_insert_pages);
1968
1969/**
1970 * vm_insert_page - insert single page into user vma
1971 * @vma: user vma to map to
1972 * @addr: target user address of this page
1973 * @page: source kernel page
1974 *
1975 * This allows drivers to insert individual pages they've allocated
1976 * into a user vma.
1977 *
1978 * The page has to be a nice clean _individual_ kernel allocation.
1979 * If you allocate a compound page, you need to have marked it as
1980 * such (__GFP_COMP), or manually just split the page up yourself
1981 * (see split_page()).
1982 *
1983 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1984 * took an arbitrary page protection parameter. This doesn't allow
1985 * that. Your vma protection will have to be set up correctly, which
1986 * means that if you want a shared writable mapping, you'd better
1987 * ask for a shared writable mapping!
1988 *
1989 * The page does not need to be reserved.
1990 *
1991 * Usually this function is called from f_op->mmap() handler
1992 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
1993 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1994 * function from other places, for example from page-fault handler.
1995 *
1996 * Return: %0 on success, negative error code otherwise.
1997 */
1998int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1999 struct page *page)
2000{
2001 if (addr < vma->vm_start || addr >= vma->vm_end)
2002 return -EFAULT;
2003 if (!page_count(page))
2004 return -EINVAL;
2005 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2006 BUG_ON(mmap_read_trylock(vma->vm_mm));
2007 BUG_ON(vma->vm_flags & VM_PFNMAP);
2008 vma->vm_flags |= VM_MIXEDMAP;
2009 }
2010 return insert_page(vma, addr, page, vma->vm_page_prot);
2011}
2012EXPORT_SYMBOL(vm_insert_page);
2013
2014/*
2015 * __vm_map_pages - maps range of kernel pages into user vma
2016 * @vma: user vma to map to
2017 * @pages: pointer to array of source kernel pages
2018 * @num: number of pages in page array
2019 * @offset: user's requested vm_pgoff
2020 *
2021 * This allows drivers to map range of kernel pages into a user vma.
2022 *
2023 * Return: 0 on success and error code otherwise.
2024 */
2025static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2026 unsigned long num, unsigned long offset)
2027{
2028 unsigned long count = vma_pages(vma);
2029 unsigned long uaddr = vma->vm_start;
2030 int ret, i;
2031
2032 /* Fail if the user requested offset is beyond the end of the object */
2033 if (offset >= num)
2034 return -ENXIO;
2035
2036 /* Fail if the user requested size exceeds available object size */
2037 if (count > num - offset)
2038 return -ENXIO;
2039
2040 for (i = 0; i < count; i++) {
2041 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
2042 if (ret < 0)
2043 return ret;
2044 uaddr += PAGE_SIZE;
2045 }
2046
2047 return 0;
2048}
2049
2050/**
2051 * vm_map_pages - maps range of kernel pages starts with non zero offset
2052 * @vma: user vma to map to
2053 * @pages: pointer to array of source kernel pages
2054 * @num: number of pages in page array
2055 *
2056 * Maps an object consisting of @num pages, catering for the user's
2057 * requested vm_pgoff
2058 *
2059 * If we fail to insert any page into the vma, the function will return
2060 * immediately leaving any previously inserted pages present. Callers
2061 * from the mmap handler may immediately return the error as their caller
2062 * will destroy the vma, removing any successfully inserted pages. Other
2063 * callers should make their own arrangements for calling unmap_region().
2064 *
2065 * Context: Process context. Called by mmap handlers.
2066 * Return: 0 on success and error code otherwise.
2067 */
2068int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2069 unsigned long num)
2070{
2071 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2072}
2073EXPORT_SYMBOL(vm_map_pages);
2074
2075/**
2076 * vm_map_pages_zero - map range of kernel pages starts with zero offset
2077 * @vma: user vma to map to
2078 * @pages: pointer to array of source kernel pages
2079 * @num: number of pages in page array
2080 *
2081 * Similar to vm_map_pages(), except that it explicitly sets the offset
2082 * to 0. This function is intended for the drivers that did not consider
2083 * vm_pgoff.
2084 *
2085 * Context: Process context. Called by mmap handlers.
2086 * Return: 0 on success and error code otherwise.
2087 */
2088int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2089 unsigned long num)
2090{
2091 return __vm_map_pages(vma, pages, num, 0);
2092}
2093EXPORT_SYMBOL(vm_map_pages_zero);
2094
2095static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2096 pfn_t pfn, pgprot_t prot, bool mkwrite)
2097{
2098 struct mm_struct *mm = vma->vm_mm;
2099 pte_t *pte, entry;
2100 spinlock_t *ptl;
2101
2102 pte = get_locked_pte(mm, addr, &ptl);
2103 if (!pte)
2104 return VM_FAULT_OOM;
2105 if (!pte_none(*pte)) {
2106 if (mkwrite) {
2107 /*
2108 * For read faults on private mappings the PFN passed
2109 * in may not match the PFN we have mapped if the
2110 * mapped PFN is a writeable COW page. In the mkwrite
2111 * case we are creating a writable PTE for a shared
2112 * mapping and we expect the PFNs to match. If they
2113 * don't match, we are likely racing with block
2114 * allocation and mapping invalidation so just skip the
2115 * update.
2116 */
2117 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
2118 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
2119 goto out_unlock;
2120 }
2121 entry = pte_mkyoung(*pte);
2122 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2123 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2124 update_mmu_cache(vma, addr, pte);
2125 }
2126 goto out_unlock;
2127 }
2128
2129 /* Ok, finally just insert the thing.. */
2130 if (pfn_t_devmap(pfn))
2131 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2132 else
2133 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2134
2135 if (mkwrite) {
2136 entry = pte_mkyoung(entry);
2137 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2138 }
2139
2140 set_pte_at(mm, addr, pte, entry);
2141 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2142
2143out_unlock:
2144 pte_unmap_unlock(pte, ptl);
2145 return VM_FAULT_NOPAGE;
2146}
2147
2148/**
2149 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2150 * @vma: user vma to map to
2151 * @addr: target user address of this page
2152 * @pfn: source kernel pfn
2153 * @pgprot: pgprot flags for the inserted page
2154 *
2155 * This is exactly like vmf_insert_pfn(), except that it allows drivers
2156 * to override pgprot on a per-page basis.
2157 *
2158 * This only makes sense for IO mappings, and it makes no sense for
2159 * COW mappings. In general, using multiple vmas is preferable;
2160 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2161 * impractical.
2162 *
2163 * See vmf_insert_mixed_prot() for a discussion of the implication of using
2164 * a value of @pgprot different from that of @vma->vm_page_prot.
2165 *
2166 * Context: Process context. May allocate using %GFP_KERNEL.
2167 * Return: vm_fault_t value.
2168 */
2169vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2170 unsigned long pfn, pgprot_t pgprot)
2171{
2172 /*
2173 * Technically, architectures with pte_special can avoid all these
2174 * restrictions (same for remap_pfn_range). However we would like
2175 * consistency in testing and feature parity among all, so we should
2176 * try to keep these invariants in place for everybody.
2177 */
2178 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2179 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2180 (VM_PFNMAP|VM_MIXEDMAP));
2181 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2182 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2183
2184 if (addr < vma->vm_start || addr >= vma->vm_end)
2185 return VM_FAULT_SIGBUS;
2186
2187 if (!pfn_modify_allowed(pfn, pgprot))
2188 return VM_FAULT_SIGBUS;
2189
2190 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2191
2192 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2193 false);
2194}
2195EXPORT_SYMBOL(vmf_insert_pfn_prot);
2196
2197/**
2198 * vmf_insert_pfn - insert single pfn into user vma
2199 * @vma: user vma to map to
2200 * @addr: target user address of this page
2201 * @pfn: source kernel pfn
2202 *
2203 * Similar to vm_insert_page, this allows drivers to insert individual pages
2204 * they've allocated into a user vma. Same comments apply.
2205 *
2206 * This function should only be called from a vm_ops->fault handler, and
2207 * in that case the handler should return the result of this function.
2208 *
2209 * vma cannot be a COW mapping.
2210 *
2211 * As this is called only for pages that do not currently exist, we
2212 * do not need to flush old virtual caches or the TLB.
2213 *
2214 * Context: Process context. May allocate using %GFP_KERNEL.
2215 * Return: vm_fault_t value.
2216 */
2217vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2218 unsigned long pfn)
2219{
2220 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2221}
2222EXPORT_SYMBOL(vmf_insert_pfn);
2223
2224static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
2225{
2226 /* these checks mirror the abort conditions in vm_normal_page */
2227 if (vma->vm_flags & VM_MIXEDMAP)
2228 return true;
2229 if (pfn_t_devmap(pfn))
2230 return true;
2231 if (pfn_t_special(pfn))
2232 return true;
2233 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2234 return true;
2235 return false;
2236}
2237
2238static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2239 unsigned long addr, pfn_t pfn, pgprot_t pgprot,
2240 bool mkwrite)
2241{
2242 int err;
2243
2244 BUG_ON(!vm_mixed_ok(vma, pfn));
2245
2246 if (addr < vma->vm_start || addr >= vma->vm_end)
2247 return VM_FAULT_SIGBUS;
2248
2249 track_pfn_insert(vma, &pgprot, pfn);
2250
2251 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2252 return VM_FAULT_SIGBUS;
2253
2254 /*
2255 * If we don't have pte special, then we have to use the pfn_valid()
2256 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2257 * refcount the page if pfn_valid is true (hence insert_page rather
2258 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2259 * without pte special, it would there be refcounted as a normal page.
2260 */
2261 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2262 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2263 struct page *page;
2264
2265 /*
2266 * At this point we are committed to insert_page()
2267 * regardless of whether the caller specified flags that
2268 * result in pfn_t_has_page() == false.
2269 */
2270 page = pfn_to_page(pfn_t_to_pfn(pfn));
2271 err = insert_page(vma, addr, page, pgprot);
2272 } else {
2273 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2274 }
2275
2276 if (err == -ENOMEM)
2277 return VM_FAULT_OOM;
2278 if (err < 0 && err != -EBUSY)
2279 return VM_FAULT_SIGBUS;
2280
2281 return VM_FAULT_NOPAGE;
2282}
2283
2284/**
2285 * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
2286 * @vma: user vma to map to
2287 * @addr: target user address of this page
2288 * @pfn: source kernel pfn
2289 * @pgprot: pgprot flags for the inserted page
2290 *
2291 * This is exactly like vmf_insert_mixed(), except that it allows drivers
2292 * to override pgprot on a per-page basis.
2293 *
2294 * Typically this function should be used by drivers to set caching- and
2295 * encryption bits different than those of @vma->vm_page_prot, because
2296 * the caching- or encryption mode may not be known at mmap() time.
2297 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2298 * to set caching and encryption bits for those vmas (except for COW pages).
2299 * This is ensured by core vm only modifying these page table entries using
2300 * functions that don't touch caching- or encryption bits, using pte_modify()
2301 * if needed. (See for example mprotect()).
2302 * Also when new page-table entries are created, this is only done using the
2303 * fault() callback, and never using the value of vma->vm_page_prot,
2304 * except for page-table entries that point to anonymous pages as the result
2305 * of COW.
2306 *
2307 * Context: Process context. May allocate using %GFP_KERNEL.
2308 * Return: vm_fault_t value.
2309 */
2310vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
2311 pfn_t pfn, pgprot_t pgprot)
2312{
2313 return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
2314}
2315EXPORT_SYMBOL(vmf_insert_mixed_prot);
2316
2317vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2318 pfn_t pfn)
2319{
2320 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
2321}
2322EXPORT_SYMBOL(vmf_insert_mixed);
2323
2324/*
2325 * If the insertion of PTE failed because someone else already added a
2326 * different entry in the mean time, we treat that as success as we assume
2327 * the same entry was actually inserted.
2328 */
2329vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2330 unsigned long addr, pfn_t pfn)
2331{
2332 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
2333}
2334EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2335
2336/*
2337 * maps a range of physical memory into the requested pages. the old
2338 * mappings are removed. any references to nonexistent pages results
2339 * in null mappings (currently treated as "copy-on-access")
2340 */
2341static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2342 unsigned long addr, unsigned long end,
2343 unsigned long pfn, pgprot_t prot)
2344{
2345 pte_t *pte, *mapped_pte;
2346 spinlock_t *ptl;
2347 int err = 0;
2348
2349 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2350 if (!pte)
2351 return -ENOMEM;
2352 arch_enter_lazy_mmu_mode();
2353 do {
2354 BUG_ON(!pte_none(*pte));
2355 if (!pfn_modify_allowed(pfn, prot)) {
2356 err = -EACCES;
2357 break;
2358 }
2359 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2360 pfn++;
2361 } while (pte++, addr += PAGE_SIZE, addr != end);
2362 arch_leave_lazy_mmu_mode();
2363 pte_unmap_unlock(mapped_pte, ptl);
2364 return err;
2365}
2366
2367static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2368 unsigned long addr, unsigned long end,
2369 unsigned long pfn, pgprot_t prot)
2370{
2371 pmd_t *pmd;
2372 unsigned long next;
2373 int err;
2374
2375 pfn -= addr >> PAGE_SHIFT;
2376 pmd = pmd_alloc(mm, pud, addr);
2377 if (!pmd)
2378 return -ENOMEM;
2379 VM_BUG_ON(pmd_trans_huge(*pmd));
2380 do {
2381 next = pmd_addr_end(addr, end);
2382 err = remap_pte_range(mm, pmd, addr, next,
2383 pfn + (addr >> PAGE_SHIFT), prot);
2384 if (err)
2385 return err;
2386 } while (pmd++, addr = next, addr != end);
2387 return 0;
2388}
2389
2390static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2391 unsigned long addr, unsigned long end,
2392 unsigned long pfn, pgprot_t prot)
2393{
2394 pud_t *pud;
2395 unsigned long next;
2396 int err;
2397
2398 pfn -= addr >> PAGE_SHIFT;
2399 pud = pud_alloc(mm, p4d, addr);
2400 if (!pud)
2401 return -ENOMEM;
2402 do {
2403 next = pud_addr_end(addr, end);
2404 err = remap_pmd_range(mm, pud, addr, next,
2405 pfn + (addr >> PAGE_SHIFT), prot);
2406 if (err)
2407 return err;
2408 } while (pud++, addr = next, addr != end);
2409 return 0;
2410}
2411
2412static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2413 unsigned long addr, unsigned long end,
2414 unsigned long pfn, pgprot_t prot)
2415{
2416 p4d_t *p4d;
2417 unsigned long next;
2418 int err;
2419
2420 pfn -= addr >> PAGE_SHIFT;
2421 p4d = p4d_alloc(mm, pgd, addr);
2422 if (!p4d)
2423 return -ENOMEM;
2424 do {
2425 next = p4d_addr_end(addr, end);
2426 err = remap_pud_range(mm, p4d, addr, next,
2427 pfn + (addr >> PAGE_SHIFT), prot);
2428 if (err)
2429 return err;
2430 } while (p4d++, addr = next, addr != end);
2431 return 0;
2432}
2433
2434/*
2435 * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
2436 * must have pre-validated the caching bits of the pgprot_t.
2437 */
2438int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2439 unsigned long pfn, unsigned long size, pgprot_t prot)
2440{
2441 pgd_t *pgd;
2442 unsigned long next;
2443 unsigned long end = addr + PAGE_ALIGN(size);
2444 struct mm_struct *mm = vma->vm_mm;
2445 int err;
2446
2447 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2448 return -EINVAL;
2449
2450 /*
2451 * Physically remapped pages are special. Tell the
2452 * rest of the world about it:
2453 * VM_IO tells people not to look at these pages
2454 * (accesses can have side effects).
2455 * VM_PFNMAP tells the core MM that the base pages are just
2456 * raw PFN mappings, and do not have a "struct page" associated
2457 * with them.
2458 * VM_DONTEXPAND
2459 * Disable vma merging and expanding with mremap().
2460 * VM_DONTDUMP
2461 * Omit vma from core dump, even when VM_IO turned off.
2462 *
2463 * There's a horrible special case to handle copy-on-write
2464 * behaviour that some programs depend on. We mark the "original"
2465 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2466 * See vm_normal_page() for details.
2467 */
2468 if (is_cow_mapping(vma->vm_flags)) {
2469 if (addr != vma->vm_start || end != vma->vm_end)
2470 return -EINVAL;
2471 vma->vm_pgoff = pfn;
2472 }
2473
2474 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2475
2476 BUG_ON(addr >= end);
2477 pfn -= addr >> PAGE_SHIFT;
2478 pgd = pgd_offset(mm, addr);
2479 flush_cache_range(vma, addr, end);
2480 do {
2481 next = pgd_addr_end(addr, end);
2482 err = remap_p4d_range(mm, pgd, addr, next,
2483 pfn + (addr >> PAGE_SHIFT), prot);
2484 if (err)
2485 return err;
2486 } while (pgd++, addr = next, addr != end);
2487
2488 return 0;
2489}
2490
2491/**
2492 * remap_pfn_range - remap kernel memory to userspace
2493 * @vma: user vma to map to
2494 * @addr: target page aligned user address to start at
2495 * @pfn: page frame number of kernel physical memory address
2496 * @size: size of mapping area
2497 * @prot: page protection flags for this mapping
2498 *
2499 * Note: this is only safe if the mm semaphore is held when called.
2500 *
2501 * Return: %0 on success, negative error code otherwise.
2502 */
2503int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2504 unsigned long pfn, unsigned long size, pgprot_t prot)
2505{
2506 int err;
2507
2508 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2509 if (err)
2510 return -EINVAL;
2511
2512 err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2513 if (err)
2514 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2515 return err;
2516}
2517EXPORT_SYMBOL(remap_pfn_range);
2518
2519/**
2520 * vm_iomap_memory - remap memory to userspace
2521 * @vma: user vma to map to
2522 * @start: start of the physical memory to be mapped
2523 * @len: size of area
2524 *
2525 * This is a simplified io_remap_pfn_range() for common driver use. The
2526 * driver just needs to give us the physical memory range to be mapped,
2527 * we'll figure out the rest from the vma information.
2528 *
2529 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2530 * whatever write-combining details or similar.
2531 *
2532 * Return: %0 on success, negative error code otherwise.
2533 */
2534int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2535{
2536 unsigned long vm_len, pfn, pages;
2537
2538 /* Check that the physical memory area passed in looks valid */
2539 if (start + len < start)
2540 return -EINVAL;
2541 /*
2542 * You *really* shouldn't map things that aren't page-aligned,
2543 * but we've historically allowed it because IO memory might
2544 * just have smaller alignment.
2545 */
2546 len += start & ~PAGE_MASK;
2547 pfn = start >> PAGE_SHIFT;
2548 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2549 if (pfn + pages < pfn)
2550 return -EINVAL;
2551
2552 /* We start the mapping 'vm_pgoff' pages into the area */
2553 if (vma->vm_pgoff > pages)
2554 return -EINVAL;
2555 pfn += vma->vm_pgoff;
2556 pages -= vma->vm_pgoff;
2557
2558 /* Can we fit all of the mapping? */
2559 vm_len = vma->vm_end - vma->vm_start;
2560 if (vm_len >> PAGE_SHIFT > pages)
2561 return -EINVAL;
2562
2563 /* Ok, let it rip */
2564 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2565}
2566EXPORT_SYMBOL(vm_iomap_memory);
2567
2568static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2569 unsigned long addr, unsigned long end,
2570 pte_fn_t fn, void *data, bool create,
2571 pgtbl_mod_mask *mask)
2572{
2573 pte_t *pte, *mapped_pte;
2574 int err = 0;
2575 spinlock_t *ptl;
2576
2577 if (create) {
2578 mapped_pte = pte = (mm == &init_mm) ?
2579 pte_alloc_kernel_track(pmd, addr, mask) :
2580 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2581 if (!pte)
2582 return -ENOMEM;
2583 } else {
2584 mapped_pte = pte = (mm == &init_mm) ?
2585 pte_offset_kernel(pmd, addr) :
2586 pte_offset_map_lock(mm, pmd, addr, &ptl);
2587 }
2588
2589 BUG_ON(pmd_huge(*pmd));
2590
2591 arch_enter_lazy_mmu_mode();
2592
2593 if (fn) {
2594 do {
2595 if (create || !pte_none(*pte)) {
2596 err = fn(pte++, addr, data);
2597 if (err)
2598 break;
2599 }
2600 } while (addr += PAGE_SIZE, addr != end);
2601 }
2602 *mask |= PGTBL_PTE_MODIFIED;
2603
2604 arch_leave_lazy_mmu_mode();
2605
2606 if (mm != &init_mm)
2607 pte_unmap_unlock(mapped_pte, ptl);
2608 return err;
2609}
2610
2611static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2612 unsigned long addr, unsigned long end,
2613 pte_fn_t fn, void *data, bool create,
2614 pgtbl_mod_mask *mask)
2615{
2616 pmd_t *pmd;
2617 unsigned long next;
2618 int err = 0;
2619
2620 BUG_ON(pud_huge(*pud));
2621
2622 if (create) {
2623 pmd = pmd_alloc_track(mm, pud, addr, mask);
2624 if (!pmd)
2625 return -ENOMEM;
2626 } else {
2627 pmd = pmd_offset(pud, addr);
2628 }
2629 do {
2630 next = pmd_addr_end(addr, end);
2631 if (pmd_none(*pmd) && !create)
2632 continue;
2633 if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2634 return -EINVAL;
2635 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2636 if (!create)
2637 continue;
2638 pmd_clear_bad(pmd);
2639 }
2640 err = apply_to_pte_range(mm, pmd, addr, next,
2641 fn, data, create, mask);
2642 if (err)
2643 break;
2644 } while (pmd++, addr = next, addr != end);
2645
2646 return err;
2647}
2648
2649static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2650 unsigned long addr, unsigned long end,
2651 pte_fn_t fn, void *data, bool create,
2652 pgtbl_mod_mask *mask)
2653{
2654 pud_t *pud;
2655 unsigned long next;
2656 int err = 0;
2657
2658 if (create) {
2659 pud = pud_alloc_track(mm, p4d, addr, mask);
2660 if (!pud)
2661 return -ENOMEM;
2662 } else {
2663 pud = pud_offset(p4d, addr);
2664 }
2665 do {
2666 next = pud_addr_end(addr, end);
2667 if (pud_none(*pud) && !create)
2668 continue;
2669 if (WARN_ON_ONCE(pud_leaf(*pud)))
2670 return -EINVAL;
2671 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2672 if (!create)
2673 continue;
2674 pud_clear_bad(pud);
2675 }
2676 err = apply_to_pmd_range(mm, pud, addr, next,
2677 fn, data, create, mask);
2678 if (err)
2679 break;
2680 } while (pud++, addr = next, addr != end);
2681
2682 return err;
2683}
2684
2685static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2686 unsigned long addr, unsigned long end,
2687 pte_fn_t fn, void *data, bool create,
2688 pgtbl_mod_mask *mask)
2689{
2690 p4d_t *p4d;
2691 unsigned long next;
2692 int err = 0;
2693
2694 if (create) {
2695 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2696 if (!p4d)
2697 return -ENOMEM;
2698 } else {
2699 p4d = p4d_offset(pgd, addr);
2700 }
2701 do {
2702 next = p4d_addr_end(addr, end);
2703 if (p4d_none(*p4d) && !create)
2704 continue;
2705 if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2706 return -EINVAL;
2707 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2708 if (!create)
2709 continue;
2710 p4d_clear_bad(p4d);
2711 }
2712 err = apply_to_pud_range(mm, p4d, addr, next,
2713 fn, data, create, mask);
2714 if (err)
2715 break;
2716 } while (p4d++, addr = next, addr != end);
2717
2718 return err;
2719}
2720
2721static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2722 unsigned long size, pte_fn_t fn,
2723 void *data, bool create)
2724{
2725 pgd_t *pgd;
2726 unsigned long start = addr, next;
2727 unsigned long end = addr + size;
2728 pgtbl_mod_mask mask = 0;
2729 int err = 0;
2730
2731 if (WARN_ON(addr >= end))
2732 return -EINVAL;
2733
2734 pgd = pgd_offset(mm, addr);
2735 do {
2736 next = pgd_addr_end(addr, end);
2737 if (pgd_none(*pgd) && !create)
2738 continue;
2739 if (WARN_ON_ONCE(pgd_leaf(*pgd)))
2740 return -EINVAL;
2741 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2742 if (!create)
2743 continue;
2744 pgd_clear_bad(pgd);
2745 }
2746 err = apply_to_p4d_range(mm, pgd, addr, next,
2747 fn, data, create, &mask);
2748 if (err)
2749 break;
2750 } while (pgd++, addr = next, addr != end);
2751
2752 if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2753 arch_sync_kernel_mappings(start, start + size);
2754
2755 return err;
2756}
2757
2758/*
2759 * Scan a region of virtual memory, filling in page tables as necessary
2760 * and calling a provided function on each leaf page table.
2761 */
2762int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2763 unsigned long size, pte_fn_t fn, void *data)
2764{
2765 return __apply_to_page_range(mm, addr, size, fn, data, true);
2766}
2767EXPORT_SYMBOL_GPL(apply_to_page_range);
2768
2769/*
2770 * Scan a region of virtual memory, calling a provided function on
2771 * each leaf page table where it exists.
2772 *
2773 * Unlike apply_to_page_range, this does _not_ fill in page tables
2774 * where they are absent.
2775 */
2776int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
2777 unsigned long size, pte_fn_t fn, void *data)
2778{
2779 return __apply_to_page_range(mm, addr, size, fn, data, false);
2780}
2781EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
2782
2783/*
2784 * handle_pte_fault chooses page fault handler according to an entry which was
2785 * read non-atomically. Before making any commitment, on those architectures
2786 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2787 * parts, do_swap_page must check under lock before unmapping the pte and
2788 * proceeding (but do_wp_page is only called after already making such a check;
2789 * and do_anonymous_page can safely check later on).
2790 */
2791static inline int pte_unmap_same(struct vm_fault *vmf)
2792{
2793 int same = 1;
2794#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2795 if (sizeof(pte_t) > sizeof(unsigned long)) {
2796 spinlock_t *ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
2797 spin_lock(ptl);
2798 same = pte_same(*vmf->pte, vmf->orig_pte);
2799 spin_unlock(ptl);
2800 }
2801#endif
2802 pte_unmap(vmf->pte);
2803 vmf->pte = NULL;
2804 return same;
2805}
2806
2807/*
2808 * Return:
2809 * 0: copied succeeded
2810 * -EHWPOISON: copy failed due to hwpoison in source page
2811 * -EAGAIN: copied failed (some other reason)
2812 */
2813static inline int __wp_page_copy_user(struct page *dst, struct page *src,
2814 struct vm_fault *vmf)
2815{
2816 int ret;
2817 void *kaddr;
2818 void __user *uaddr;
2819 bool locked = false;
2820 struct vm_area_struct *vma = vmf->vma;
2821 struct mm_struct *mm = vma->vm_mm;
2822 unsigned long addr = vmf->address;
2823
2824 if (likely(src)) {
2825 if (copy_mc_user_highpage(dst, src, addr, vma)) {
2826 memory_failure_queue(page_to_pfn(src), 0);
2827 return -EHWPOISON;
2828 }
2829 return 0;
2830 }
2831
2832 /*
2833 * If the source page was a PFN mapping, we don't have
2834 * a "struct page" for it. We do a best-effort copy by
2835 * just copying from the original user address. If that
2836 * fails, we just zero-fill it. Live with it.
2837 */
2838 kaddr = kmap_atomic(dst);
2839 uaddr = (void __user *)(addr & PAGE_MASK);
2840
2841 /*
2842 * On architectures with software "accessed" bits, we would
2843 * take a double page fault, so mark it accessed here.
2844 */
2845 if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
2846 pte_t entry;
2847
2848 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2849 locked = true;
2850 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2851 /*
2852 * Other thread has already handled the fault
2853 * and update local tlb only
2854 */
2855 update_mmu_tlb(vma, addr, vmf->pte);
2856 ret = -EAGAIN;
2857 goto pte_unlock;
2858 }
2859
2860 entry = pte_mkyoung(vmf->orig_pte);
2861 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2862 update_mmu_cache(vma, addr, vmf->pte);
2863 }
2864
2865 /*
2866 * This really shouldn't fail, because the page is there
2867 * in the page tables. But it might just be unreadable,
2868 * in which case we just give up and fill the result with
2869 * zeroes.
2870 */
2871 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2872 if (locked)
2873 goto warn;
2874
2875 /* Re-validate under PTL if the page is still mapped */
2876 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2877 locked = true;
2878 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2879 /* The PTE changed under us, update local tlb */
2880 update_mmu_tlb(vma, addr, vmf->pte);
2881 ret = -EAGAIN;
2882 goto pte_unlock;
2883 }
2884
2885 /*
2886 * The same page can be mapped back since last copy attempt.
2887 * Try to copy again under PTL.
2888 */
2889 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2890 /*
2891 * Give a warn in case there can be some obscure
2892 * use-case
2893 */
2894warn:
2895 WARN_ON_ONCE(1);
2896 clear_page(kaddr);
2897 }
2898 }
2899
2900 ret = 0;
2901
2902pte_unlock:
2903 if (locked)
2904 pte_unmap_unlock(vmf->pte, vmf->ptl);
2905 kunmap_atomic(kaddr);
2906 flush_dcache_page(dst);
2907
2908 return ret;
2909}
2910
2911static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2912{
2913 struct file *vm_file = vma->vm_file;
2914
2915 if (vm_file)
2916 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2917
2918 /*
2919 * Special mappings (e.g. VDSO) do not have any file so fake
2920 * a default GFP_KERNEL for them.
2921 */
2922 return GFP_KERNEL;
2923}
2924
2925/*
2926 * Notify the address space that the page is about to become writable so that
2927 * it can prohibit this or wait for the page to get into an appropriate state.
2928 *
2929 * We do this without the lock held, so that it can sleep if it needs to.
2930 */
2931static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2932{
2933 vm_fault_t ret;
2934 struct page *page = vmf->page;
2935 unsigned int old_flags = vmf->flags;
2936
2937 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2938
2939 if (vmf->vma->vm_file &&
2940 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2941 return VM_FAULT_SIGBUS;
2942
2943 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2944 /* Restore original flags so that caller is not surprised */
2945 vmf->flags = old_flags;
2946 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2947 return ret;
2948 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2949 lock_page(page);
2950 if (!page->mapping) {
2951 unlock_page(page);
2952 return 0; /* retry */
2953 }
2954 ret |= VM_FAULT_LOCKED;
2955 } else
2956 VM_BUG_ON_PAGE(!PageLocked(page), page);
2957 return ret;
2958}
2959
2960/*
2961 * Handle dirtying of a page in shared file mapping on a write fault.
2962 *
2963 * The function expects the page to be locked and unlocks it.
2964 */
2965static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
2966{
2967 struct vm_area_struct *vma = vmf->vma;
2968 struct address_space *mapping;
2969 struct page *page = vmf->page;
2970 bool dirtied;
2971 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2972
2973 dirtied = set_page_dirty(page);
2974 VM_BUG_ON_PAGE(PageAnon(page), page);
2975 /*
2976 * Take a local copy of the address_space - page.mapping may be zeroed
2977 * by truncate after unlock_page(). The address_space itself remains
2978 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2979 * release semantics to prevent the compiler from undoing this copying.
2980 */
2981 mapping = page_rmapping(page);
2982 unlock_page(page);
2983
2984 if (!page_mkwrite)
2985 file_update_time(vma->vm_file);
2986
2987 /*
2988 * Throttle page dirtying rate down to writeback speed.
2989 *
2990 * mapping may be NULL here because some device drivers do not
2991 * set page.mapping but still dirty their pages
2992 *
2993 * Drop the mmap_lock before waiting on IO, if we can. The file
2994 * is pinning the mapping, as per above.
2995 */
2996 if ((dirtied || page_mkwrite) && mapping) {
2997 struct file *fpin;
2998
2999 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
3000 balance_dirty_pages_ratelimited(mapping);
3001 if (fpin) {
3002 fput(fpin);
3003 return VM_FAULT_COMPLETED;
3004 }
3005 }
3006
3007 return 0;
3008}
3009
3010/*
3011 * Handle write page faults for pages that can be reused in the current vma
3012 *
3013 * This can happen either due to the mapping being with the VM_SHARED flag,
3014 * or due to us being the last reference standing to the page. In either
3015 * case, all we need to do here is to mark the page as writable and update
3016 * any related book-keeping.
3017 */
3018static inline void wp_page_reuse(struct vm_fault *vmf)
3019 __releases(vmf->ptl)
3020{
3021 struct vm_area_struct *vma = vmf->vma;
3022 struct page *page = vmf->page;
3023 pte_t entry;
3024
3025 VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE));
3026 VM_BUG_ON(page && PageAnon(page) && !PageAnonExclusive(page));
3027
3028 /*
3029 * Clear the pages cpupid information as the existing
3030 * information potentially belongs to a now completely
3031 * unrelated process.
3032 */
3033 if (page)
3034 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
3035
3036 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3037 entry = pte_mkyoung(vmf->orig_pte);
3038 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3039 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
3040 update_mmu_cache(vma, vmf->address, vmf->pte);
3041 pte_unmap_unlock(vmf->pte, vmf->ptl);
3042 count_vm_event(PGREUSE);
3043}
3044
3045/*
3046 * Handle the case of a page which we actually need to copy to a new page,
3047 * either due to COW or unsharing.
3048 *
3049 * Called with mmap_lock locked and the old page referenced, but
3050 * without the ptl held.
3051 *
3052 * High level logic flow:
3053 *
3054 * - Allocate a page, copy the content of the old page to the new one.
3055 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
3056 * - Take the PTL. If the pte changed, bail out and release the allocated page
3057 * - If the pte is still the way we remember it, update the page table and all
3058 * relevant references. This includes dropping the reference the page-table
3059 * held to the old page, as well as updating the rmap.
3060 * - In any case, unlock the PTL and drop the reference we took to the old page.
3061 */
3062static vm_fault_t wp_page_copy(struct vm_fault *vmf)
3063{
3064 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3065 struct vm_area_struct *vma = vmf->vma;
3066 struct mm_struct *mm = vma->vm_mm;
3067 struct page *old_page = vmf->page;
3068 struct page *new_page = NULL;
3069 pte_t entry;
3070 int page_copied = 0;
3071 struct mmu_notifier_range range;
3072 int ret;
3073
3074 delayacct_wpcopy_start();
3075
3076 if (unlikely(anon_vma_prepare(vma)))
3077 goto oom;
3078
3079 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
3080 new_page = alloc_zeroed_user_highpage_movable(vma,
3081 vmf->address);
3082 if (!new_page)
3083 goto oom;
3084 } else {
3085 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3086 vmf->address);
3087 if (!new_page)
3088 goto oom;
3089
3090 ret = __wp_page_copy_user(new_page, old_page, vmf);
3091 if (ret) {
3092 /*
3093 * COW failed, if the fault was solved by other,
3094 * it's fine. If not, userspace would re-fault on
3095 * the same address and we will handle the fault
3096 * from the second attempt.
3097 * The -EHWPOISON case will not be retried.
3098 */
3099 put_page(new_page);
3100 if (old_page)
3101 put_page(old_page);
3102
3103 delayacct_wpcopy_end();
3104 return ret == -EHWPOISON ? VM_FAULT_HWPOISON : 0;
3105 }
3106 kmsan_copy_page_meta(new_page, old_page);
3107 }
3108
3109 if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL))
3110 goto oom_free_new;
3111 cgroup_throttle_swaprate(new_page, GFP_KERNEL);
3112
3113 __SetPageUptodate(new_page);
3114
3115 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
3116 vmf->address & PAGE_MASK,
3117 (vmf->address & PAGE_MASK) + PAGE_SIZE);
3118 mmu_notifier_invalidate_range_start(&range);
3119
3120 /*
3121 * Re-check the pte - we dropped the lock
3122 */
3123 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3124 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
3125 if (old_page) {
3126 if (!PageAnon(old_page)) {
3127 dec_mm_counter(mm, mm_counter_file(old_page));
3128 inc_mm_counter(mm, MM_ANONPAGES);
3129 }
3130 } else {
3131 inc_mm_counter(mm, MM_ANONPAGES);
3132 }
3133 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3134 entry = mk_pte(new_page, vma->vm_page_prot);
3135 entry = pte_sw_mkyoung(entry);
3136 if (unlikely(unshare)) {
3137 if (pte_soft_dirty(vmf->orig_pte))
3138 entry = pte_mksoft_dirty(entry);
3139 if (pte_uffd_wp(vmf->orig_pte))
3140 entry = pte_mkuffd_wp(entry);
3141 } else {
3142 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3143 }
3144
3145 /*
3146 * Clear the pte entry and flush it first, before updating the
3147 * pte with the new entry, to keep TLBs on different CPUs in
3148 * sync. This code used to set the new PTE then flush TLBs, but
3149 * that left a window where the new PTE could be loaded into
3150 * some TLBs while the old PTE remains in others.
3151 */
3152 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
3153 page_add_new_anon_rmap(new_page, vma, vmf->address);
3154 lru_cache_add_inactive_or_unevictable(new_page, vma);
3155 /*
3156 * We call the notify macro here because, when using secondary
3157 * mmu page tables (such as kvm shadow page tables), we want the
3158 * new page to be mapped directly into the secondary page table.
3159 */
3160 BUG_ON(unshare && pte_write(entry));
3161 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
3162 update_mmu_cache(vma, vmf->address, vmf->pte);
3163 if (old_page) {
3164 /*
3165 * Only after switching the pte to the new page may
3166 * we remove the mapcount here. Otherwise another
3167 * process may come and find the rmap count decremented
3168 * before the pte is switched to the new page, and
3169 * "reuse" the old page writing into it while our pte
3170 * here still points into it and can be read by other
3171 * threads.
3172 *
3173 * The critical issue is to order this
3174 * page_remove_rmap with the ptp_clear_flush above.
3175 * Those stores are ordered by (if nothing else,)
3176 * the barrier present in the atomic_add_negative
3177 * in page_remove_rmap.
3178 *
3179 * Then the TLB flush in ptep_clear_flush ensures that
3180 * no process can access the old page before the
3181 * decremented mapcount is visible. And the old page
3182 * cannot be reused until after the decremented
3183 * mapcount is visible. So transitively, TLBs to
3184 * old page will be flushed before it can be reused.
3185 */
3186 page_remove_rmap(old_page, vma, false);
3187 }
3188
3189 /* Free the old page.. */
3190 new_page = old_page;
3191 page_copied = 1;
3192 } else {
3193 update_mmu_tlb(vma, vmf->address, vmf->pte);
3194 }
3195
3196 if (new_page)
3197 put_page(new_page);
3198
3199 pte_unmap_unlock(vmf->pte, vmf->ptl);
3200 /*
3201 * No need to double call mmu_notifier->invalidate_range() callback as
3202 * the above ptep_clear_flush_notify() did already call it.
3203 */
3204 mmu_notifier_invalidate_range_only_end(&range);
3205 if (old_page) {
3206 if (page_copied)
3207 free_swap_cache(old_page);
3208 put_page(old_page);
3209 }
3210
3211 delayacct_wpcopy_end();
3212 return 0;
3213oom_free_new:
3214 put_page(new_page);
3215oom:
3216 if (old_page)
3217 put_page(old_page);
3218
3219 delayacct_wpcopy_end();
3220 return VM_FAULT_OOM;
3221}
3222
3223/**
3224 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3225 * writeable once the page is prepared
3226 *
3227 * @vmf: structure describing the fault
3228 *
3229 * This function handles all that is needed to finish a write page fault in a
3230 * shared mapping due to PTE being read-only once the mapped page is prepared.
3231 * It handles locking of PTE and modifying it.
3232 *
3233 * The function expects the page to be locked or other protection against
3234 * concurrent faults / writeback (such as DAX radix tree locks).
3235 *
3236 * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3237 * we acquired PTE lock.
3238 */
3239vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
3240{
3241 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3242 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3243 &vmf->ptl);
3244 /*
3245 * We might have raced with another page fault while we released the
3246 * pte_offset_map_lock.
3247 */
3248 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
3249 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3250 pte_unmap_unlock(vmf->pte, vmf->ptl);
3251 return VM_FAULT_NOPAGE;
3252 }
3253 wp_page_reuse(vmf);
3254 return 0;
3255}
3256
3257/*
3258 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3259 * mapping
3260 */
3261static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3262{
3263 struct vm_area_struct *vma = vmf->vma;
3264
3265 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3266 vm_fault_t ret;
3267
3268 pte_unmap_unlock(vmf->pte, vmf->ptl);
3269 vmf->flags |= FAULT_FLAG_MKWRITE;
3270 ret = vma->vm_ops->pfn_mkwrite(vmf);
3271 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3272 return ret;
3273 return finish_mkwrite_fault(vmf);
3274 }
3275 wp_page_reuse(vmf);
3276 return 0;
3277}
3278
3279static vm_fault_t wp_page_shared(struct vm_fault *vmf)
3280 __releases(vmf->ptl)
3281{
3282 struct vm_area_struct *vma = vmf->vma;
3283 vm_fault_t ret = 0;
3284
3285 get_page(vmf->page);
3286
3287 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3288 vm_fault_t tmp;
3289
3290 pte_unmap_unlock(vmf->pte, vmf->ptl);
3291 tmp = do_page_mkwrite(vmf);
3292 if (unlikely(!tmp || (tmp &
3293 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3294 put_page(vmf->page);
3295 return tmp;
3296 }
3297 tmp = finish_mkwrite_fault(vmf);
3298 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3299 unlock_page(vmf->page);
3300 put_page(vmf->page);
3301 return tmp;
3302 }
3303 } else {
3304 wp_page_reuse(vmf);
3305 lock_page(vmf->page);
3306 }
3307 ret |= fault_dirty_shared_page(vmf);
3308 put_page(vmf->page);
3309
3310 return ret;
3311}
3312
3313/*
3314 * This routine handles present pages, when
3315 * * users try to write to a shared page (FAULT_FLAG_WRITE)
3316 * * GUP wants to take a R/O pin on a possibly shared anonymous page
3317 * (FAULT_FLAG_UNSHARE)
3318 *
3319 * It is done by copying the page to a new address and decrementing the
3320 * shared-page counter for the old page.
3321 *
3322 * Note that this routine assumes that the protection checks have been
3323 * done by the caller (the low-level page fault routine in most cases).
3324 * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've
3325 * done any necessary COW.
3326 *
3327 * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even
3328 * though the page will change only once the write actually happens. This
3329 * avoids a few races, and potentially makes it more efficient.
3330 *
3331 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3332 * but allow concurrent faults), with pte both mapped and locked.
3333 * We return with mmap_lock still held, but pte unmapped and unlocked.
3334 */
3335static vm_fault_t do_wp_page(struct vm_fault *vmf)
3336 __releases(vmf->ptl)
3337{
3338 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3339 struct vm_area_struct *vma = vmf->vma;
3340 struct folio *folio = NULL;
3341
3342 if (likely(!unshare)) {
3343 if (userfaultfd_pte_wp(vma, *vmf->pte)) {
3344 pte_unmap_unlock(vmf->pte, vmf->ptl);
3345 return handle_userfault(vmf, VM_UFFD_WP);
3346 }
3347
3348 /*
3349 * Userfaultfd write-protect can defer flushes. Ensure the TLB
3350 * is flushed in this case before copying.
3351 */
3352 if (unlikely(userfaultfd_wp(vmf->vma) &&
3353 mm_tlb_flush_pending(vmf->vma->vm_mm)))
3354 flush_tlb_page(vmf->vma, vmf->address);
3355 }
3356
3357 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3358
3359 /*
3360 * Shared mapping: we are guaranteed to have VM_WRITE and
3361 * FAULT_FLAG_WRITE set at this point.
3362 */
3363 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
3364 /*
3365 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3366 * VM_PFNMAP VMA.
3367 *
3368 * We should not cow pages in a shared writeable mapping.
3369 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3370 */
3371 if (!vmf->page)
3372 return wp_pfn_shared(vmf);
3373 return wp_page_shared(vmf);
3374 }
3375
3376 if (vmf->page)
3377 folio = page_folio(vmf->page);
3378
3379 /*
3380 * Private mapping: create an exclusive anonymous page copy if reuse
3381 * is impossible. We might miss VM_WRITE for FOLL_FORCE handling.
3382 */
3383 if (folio && folio_test_anon(folio)) {
3384 /*
3385 * If the page is exclusive to this process we must reuse the
3386 * page without further checks.
3387 */
3388 if (PageAnonExclusive(vmf->page))
3389 goto reuse;
3390
3391 /*
3392 * We have to verify under folio lock: these early checks are
3393 * just an optimization to avoid locking the folio and freeing
3394 * the swapcache if there is little hope that we can reuse.
3395 *
3396 * KSM doesn't necessarily raise the folio refcount.
3397 */
3398 if (folio_test_ksm(folio) || folio_ref_count(folio) > 3)
3399 goto copy;
3400 if (!folio_test_lru(folio))
3401 /*
3402 * Note: We cannot easily detect+handle references from
3403 * remote LRU pagevecs or references to LRU folios.
3404 */
3405 lru_add_drain();
3406 if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio))
3407 goto copy;
3408 if (!folio_trylock(folio))
3409 goto copy;
3410 if (folio_test_swapcache(folio))
3411 folio_free_swap(folio);
3412 if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) {
3413 folio_unlock(folio);
3414 goto copy;
3415 }
3416 /*
3417 * Ok, we've got the only folio reference from our mapping
3418 * and the folio is locked, it's dark out, and we're wearing
3419 * sunglasses. Hit it.
3420 */
3421 page_move_anon_rmap(vmf->page, vma);
3422 folio_unlock(folio);
3423reuse:
3424 if (unlikely(unshare)) {
3425 pte_unmap_unlock(vmf->pte, vmf->ptl);
3426 return 0;
3427 }
3428 wp_page_reuse(vmf);
3429 return 0;
3430 }
3431copy:
3432 /*
3433 * Ok, we need to copy. Oh, well..
3434 */
3435 if (folio)
3436 folio_get(folio);
3437
3438 pte_unmap_unlock(vmf->pte, vmf->ptl);
3439#ifdef CONFIG_KSM
3440 if (folio && folio_test_ksm(folio))
3441 count_vm_event(COW_KSM);
3442#endif
3443 return wp_page_copy(vmf);
3444}
3445
3446static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3447 unsigned long start_addr, unsigned long end_addr,
3448 struct zap_details *details)
3449{
3450 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3451}
3452
3453static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3454 pgoff_t first_index,
3455 pgoff_t last_index,
3456 struct zap_details *details)
3457{
3458 struct vm_area_struct *vma;
3459 pgoff_t vba, vea, zba, zea;
3460
3461 vma_interval_tree_foreach(vma, root, first_index, last_index) {
3462 vba = vma->vm_pgoff;
3463 vea = vba + vma_pages(vma) - 1;
3464 zba = max(first_index, vba);
3465 zea = min(last_index, vea);
3466
3467 unmap_mapping_range_vma(vma,
3468 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3469 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3470 details);
3471 }
3472}
3473
3474/**
3475 * unmap_mapping_folio() - Unmap single folio from processes.
3476 * @folio: The locked folio to be unmapped.
3477 *
3478 * Unmap this folio from any userspace process which still has it mmaped.
3479 * Typically, for efficiency, the range of nearby pages has already been
3480 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
3481 * truncation or invalidation holds the lock on a folio, it may find that
3482 * the page has been remapped again: and then uses unmap_mapping_folio()
3483 * to unmap it finally.
3484 */
3485void unmap_mapping_folio(struct folio *folio)
3486{
3487 struct address_space *mapping = folio->mapping;
3488 struct zap_details details = { };
3489 pgoff_t first_index;
3490 pgoff_t last_index;
3491
3492 VM_BUG_ON(!folio_test_locked(folio));
3493
3494 first_index = folio->index;
3495 last_index = folio->index + folio_nr_pages(folio) - 1;
3496
3497 details.even_cows = false;
3498 details.single_folio = folio;
3499 details.zap_flags = ZAP_FLAG_DROP_MARKER;
3500
3501 i_mmap_lock_read(mapping);
3502 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3503 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3504 last_index, &details);
3505 i_mmap_unlock_read(mapping);
3506}
3507
3508/**
3509 * unmap_mapping_pages() - Unmap pages from processes.
3510 * @mapping: The address space containing pages to be unmapped.
3511 * @start: Index of first page to be unmapped.
3512 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3513 * @even_cows: Whether to unmap even private COWed pages.
3514 *
3515 * Unmap the pages in this address space from any userspace process which
3516 * has them mmaped. Generally, you want to remove COWed pages as well when
3517 * a file is being truncated, but not when invalidating pages from the page
3518 * cache.
3519 */
3520void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3521 pgoff_t nr, bool even_cows)
3522{
3523 struct zap_details details = { };
3524 pgoff_t first_index = start;
3525 pgoff_t last_index = start + nr - 1;
3526
3527 details.even_cows = even_cows;
3528 if (last_index < first_index)
3529 last_index = ULONG_MAX;
3530
3531 i_mmap_lock_read(mapping);
3532 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3533 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3534 last_index, &details);
3535 i_mmap_unlock_read(mapping);
3536}
3537EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3538
3539/**
3540 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3541 * address_space corresponding to the specified byte range in the underlying
3542 * file.
3543 *
3544 * @mapping: the address space containing mmaps to be unmapped.
3545 * @holebegin: byte in first page to unmap, relative to the start of
3546 * the underlying file. This will be rounded down to a PAGE_SIZE
3547 * boundary. Note that this is different from truncate_pagecache(), which
3548 * must keep the partial page. In contrast, we must get rid of
3549 * partial pages.
3550 * @holelen: size of prospective hole in bytes. This will be rounded
3551 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3552 * end of the file.
3553 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3554 * but 0 when invalidating pagecache, don't throw away private data.
3555 */
3556void unmap_mapping_range(struct address_space *mapping,
3557 loff_t const holebegin, loff_t const holelen, int even_cows)
3558{
3559 pgoff_t hba = holebegin >> PAGE_SHIFT;
3560 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3561
3562 /* Check for overflow. */
3563 if (sizeof(holelen) > sizeof(hlen)) {
3564 long long holeend =
3565 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3566 if (holeend & ~(long long)ULONG_MAX)
3567 hlen = ULONG_MAX - hba + 1;
3568 }
3569
3570 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3571}
3572EXPORT_SYMBOL(unmap_mapping_range);
3573
3574/*
3575 * Restore a potential device exclusive pte to a working pte entry
3576 */
3577static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3578{
3579 struct folio *folio = page_folio(vmf->page);
3580 struct vm_area_struct *vma = vmf->vma;
3581 struct mmu_notifier_range range;
3582
3583 if (!folio_lock_or_retry(folio, vma->vm_mm, vmf->flags))
3584 return VM_FAULT_RETRY;
3585 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
3586 vma->vm_mm, vmf->address & PAGE_MASK,
3587 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3588 mmu_notifier_invalidate_range_start(&range);
3589
3590 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3591 &vmf->ptl);
3592 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3593 restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
3594
3595 pte_unmap_unlock(vmf->pte, vmf->ptl);
3596 folio_unlock(folio);
3597
3598 mmu_notifier_invalidate_range_end(&range);
3599 return 0;
3600}
3601
3602static inline bool should_try_to_free_swap(struct folio *folio,
3603 struct vm_area_struct *vma,
3604 unsigned int fault_flags)
3605{
3606 if (!folio_test_swapcache(folio))
3607 return false;
3608 if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
3609 folio_test_mlocked(folio))
3610 return true;
3611 /*
3612 * If we want to map a page that's in the swapcache writable, we
3613 * have to detect via the refcount if we're really the exclusive
3614 * user. Try freeing the swapcache to get rid of the swapcache
3615 * reference only in case it's likely that we'll be the exlusive user.
3616 */
3617 return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
3618 folio_ref_count(folio) == 2;
3619}
3620
3621static vm_fault_t pte_marker_clear(struct vm_fault *vmf)
3622{
3623 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
3624 vmf->address, &vmf->ptl);
3625 /*
3626 * Be careful so that we will only recover a special uffd-wp pte into a
3627 * none pte. Otherwise it means the pte could have changed, so retry.
3628 *
3629 * This should also cover the case where e.g. the pte changed
3630 * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_SWAPIN_ERROR.
3631 * So is_pte_marker() check is not enough to safely drop the pte.
3632 */
3633 if (pte_same(vmf->orig_pte, *vmf->pte))
3634 pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte);
3635 pte_unmap_unlock(vmf->pte, vmf->ptl);
3636 return 0;
3637}
3638
3639/*
3640 * This is actually a page-missing access, but with uffd-wp special pte
3641 * installed. It means this pte was wr-protected before being unmapped.
3642 */
3643static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf)
3644{
3645 /*
3646 * Just in case there're leftover special ptes even after the region
3647 * got unregistered - we can simply clear them. We can also do that
3648 * proactively when e.g. when we do UFFDIO_UNREGISTER upon some uffd-wp
3649 * ranges, but it should be more efficient to be done lazily here.
3650 */
3651 if (unlikely(!userfaultfd_wp(vmf->vma) || vma_is_anonymous(vmf->vma)))
3652 return pte_marker_clear(vmf);
3653
3654 /* do_fault() can handle pte markers too like none pte */
3655 return do_fault(vmf);
3656}
3657
3658static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
3659{
3660 swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte);
3661 unsigned long marker = pte_marker_get(entry);
3662
3663 /*
3664 * PTE markers should never be empty. If anything weird happened,
3665 * the best thing to do is to kill the process along with its mm.
3666 */
3667 if (WARN_ON_ONCE(!marker))
3668 return VM_FAULT_SIGBUS;
3669
3670 /* Higher priority than uffd-wp when data corrupted */
3671 if (marker & PTE_MARKER_SWAPIN_ERROR)
3672 return VM_FAULT_SIGBUS;
3673
3674 if (pte_marker_entry_uffd_wp(entry))
3675 return pte_marker_handle_uffd_wp(vmf);
3676
3677 /* This is an unknown pte marker */
3678 return VM_FAULT_SIGBUS;
3679}
3680
3681/*
3682 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3683 * but allow concurrent faults), and pte mapped but not yet locked.
3684 * We return with pte unmapped and unlocked.
3685 *
3686 * We return with the mmap_lock locked or unlocked in the same cases
3687 * as does filemap_fault().
3688 */
3689vm_fault_t do_swap_page(struct vm_fault *vmf)
3690{
3691 struct vm_area_struct *vma = vmf->vma;
3692 struct folio *swapcache, *folio = NULL;
3693 struct page *page;
3694 struct swap_info_struct *si = NULL;
3695 rmap_t rmap_flags = RMAP_NONE;
3696 bool exclusive = false;
3697 swp_entry_t entry;
3698 pte_t pte;
3699 int locked;
3700 vm_fault_t ret = 0;
3701 void *shadow = NULL;
3702
3703 if (!pte_unmap_same(vmf))
3704 goto out;
3705
3706 entry = pte_to_swp_entry(vmf->orig_pte);
3707 if (unlikely(non_swap_entry(entry))) {
3708 if (is_migration_entry(entry)) {
3709 migration_entry_wait(vma->vm_mm, vmf->pmd,
3710 vmf->address);
3711 } else if (is_device_exclusive_entry(entry)) {
3712 vmf->page = pfn_swap_entry_to_page(entry);
3713 ret = remove_device_exclusive_entry(vmf);
3714 } else if (is_device_private_entry(entry)) {
3715 vmf->page = pfn_swap_entry_to_page(entry);
3716 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3717 vmf->address, &vmf->ptl);
3718 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3719 spin_unlock(vmf->ptl);
3720 goto out;
3721 }
3722
3723 /*
3724 * Get a page reference while we know the page can't be
3725 * freed.
3726 */
3727 get_page(vmf->page);
3728 pte_unmap_unlock(vmf->pte, vmf->ptl);
3729 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
3730 put_page(vmf->page);
3731 } else if (is_hwpoison_entry(entry)) {
3732 ret = VM_FAULT_HWPOISON;
3733 } else if (is_pte_marker_entry(entry)) {
3734 ret = handle_pte_marker(vmf);
3735 } else {
3736 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3737 ret = VM_FAULT_SIGBUS;
3738 }
3739 goto out;
3740 }
3741
3742 /* Prevent swapoff from happening to us. */
3743 si = get_swap_device(entry);
3744 if (unlikely(!si))
3745 goto out;
3746
3747 folio = swap_cache_get_folio(entry, vma, vmf->address);
3748 if (folio)
3749 page = folio_file_page(folio, swp_offset(entry));
3750 swapcache = folio;
3751
3752 if (!folio) {
3753 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
3754 __swap_count(entry) == 1) {
3755 /* skip swapcache */
3756 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
3757 vma, vmf->address, false);
3758 page = &folio->page;
3759 if (folio) {
3760 __folio_set_locked(folio);
3761 __folio_set_swapbacked(folio);
3762
3763 if (mem_cgroup_swapin_charge_folio(folio,
3764 vma->vm_mm, GFP_KERNEL,
3765 entry)) {
3766 ret = VM_FAULT_OOM;
3767 goto out_page;
3768 }
3769 mem_cgroup_swapin_uncharge_swap(entry);
3770
3771 shadow = get_shadow_from_swap_cache(entry);
3772 if (shadow)
3773 workingset_refault(folio, shadow);
3774
3775 folio_add_lru(folio);
3776
3777 /* To provide entry to swap_readpage() */
3778 folio_set_swap_entry(folio, entry);
3779 swap_readpage(page, true, NULL);
3780 folio->private = NULL;
3781 }
3782 } else {
3783 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3784 vmf);
3785 if (page)
3786 folio = page_folio(page);
3787 swapcache = folio;
3788 }
3789
3790 if (!folio) {
3791 /*
3792 * Back out if somebody else faulted in this pte
3793 * while we released the pte lock.
3794 */
3795 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3796 vmf->address, &vmf->ptl);
3797 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3798 ret = VM_FAULT_OOM;
3799 goto unlock;
3800 }
3801
3802 /* Had to read the page from swap area: Major fault */
3803 ret = VM_FAULT_MAJOR;
3804 count_vm_event(PGMAJFAULT);
3805 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3806 } else if (PageHWPoison(page)) {
3807 /*
3808 * hwpoisoned dirty swapcache pages are kept for killing
3809 * owner processes (which may be unknown at hwpoison time)
3810 */
3811 ret = VM_FAULT_HWPOISON;
3812 goto out_release;
3813 }
3814
3815 locked = folio_lock_or_retry(folio, vma->vm_mm, vmf->flags);
3816
3817 if (!locked) {
3818 ret |= VM_FAULT_RETRY;
3819 goto out_release;
3820 }
3821
3822 if (swapcache) {
3823 /*
3824 * Make sure folio_free_swap() or swapoff did not release the
3825 * swapcache from under us. The page pin, and pte_same test
3826 * below, are not enough to exclude that. Even if it is still
3827 * swapcache, we need to check that the page's swap has not
3828 * changed.
3829 */
3830 if (unlikely(!folio_test_swapcache(folio) ||
3831 page_private(page) != entry.val))
3832 goto out_page;
3833
3834 /*
3835 * KSM sometimes has to copy on read faults, for example, if
3836 * page->index of !PageKSM() pages would be nonlinear inside the
3837 * anon VMA -- PageKSM() is lost on actual swapout.
3838 */
3839 page = ksm_might_need_to_copy(page, vma, vmf->address);
3840 if (unlikely(!page)) {
3841 ret = VM_FAULT_OOM;
3842 goto out_page;
3843 } else if (unlikely(PTR_ERR(page) == -EHWPOISON)) {
3844 ret = VM_FAULT_HWPOISON;
3845 goto out_page;
3846 }
3847 folio = page_folio(page);
3848
3849 /*
3850 * If we want to map a page that's in the swapcache writable, we
3851 * have to detect via the refcount if we're really the exclusive
3852 * owner. Try removing the extra reference from the local LRU
3853 * pagevecs if required.
3854 */
3855 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
3856 !folio_test_ksm(folio) && !folio_test_lru(folio))
3857 lru_add_drain();
3858 }
3859
3860 cgroup_throttle_swaprate(page, GFP_KERNEL);
3861
3862 /*
3863 * Back out if somebody else already faulted in this pte.
3864 */
3865 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3866 &vmf->ptl);
3867 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3868 goto out_nomap;
3869
3870 if (unlikely(!folio_test_uptodate(folio))) {
3871 ret = VM_FAULT_SIGBUS;
3872 goto out_nomap;
3873 }
3874
3875 /*
3876 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
3877 * must never point at an anonymous page in the swapcache that is
3878 * PG_anon_exclusive. Sanity check that this holds and especially, that
3879 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
3880 * check after taking the PT lock and making sure that nobody
3881 * concurrently faulted in this page and set PG_anon_exclusive.
3882 */
3883 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
3884 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
3885
3886 /*
3887 * Check under PT lock (to protect against concurrent fork() sharing
3888 * the swap entry concurrently) for certainly exclusive pages.
3889 */
3890 if (!folio_test_ksm(folio)) {
3891 /*
3892 * Note that pte_swp_exclusive() == false for architectures
3893 * without __HAVE_ARCH_PTE_SWP_EXCLUSIVE.
3894 */
3895 exclusive = pte_swp_exclusive(vmf->orig_pte);
3896 if (folio != swapcache) {
3897 /*
3898 * We have a fresh page that is not exposed to the
3899 * swapcache -> certainly exclusive.
3900 */
3901 exclusive = true;
3902 } else if (exclusive && folio_test_writeback(folio) &&
3903 data_race(si->flags & SWP_STABLE_WRITES)) {
3904 /*
3905 * This is tricky: not all swap backends support
3906 * concurrent page modifications while under writeback.
3907 *
3908 * So if we stumble over such a page in the swapcache
3909 * we must not set the page exclusive, otherwise we can
3910 * map it writable without further checks and modify it
3911 * while still under writeback.
3912 *
3913 * For these problematic swap backends, simply drop the
3914 * exclusive marker: this is perfectly fine as we start
3915 * writeback only if we fully unmapped the page and
3916 * there are no unexpected references on the page after
3917 * unmapping succeeded. After fully unmapped, no
3918 * further GUP references (FOLL_GET and FOLL_PIN) can
3919 * appear, so dropping the exclusive marker and mapping
3920 * it only R/O is fine.
3921 */
3922 exclusive = false;
3923 }
3924 }
3925
3926 /*
3927 * Remove the swap entry and conditionally try to free up the swapcache.
3928 * We're already holding a reference on the page but haven't mapped it
3929 * yet.
3930 */
3931 swap_free(entry);
3932 if (should_try_to_free_swap(folio, vma, vmf->flags))
3933 folio_free_swap(folio);
3934
3935 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
3936 dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
3937 pte = mk_pte(page, vma->vm_page_prot);
3938
3939 /*
3940 * Same logic as in do_wp_page(); however, optimize for pages that are
3941 * certainly not shared either because we just allocated them without
3942 * exposing them to the swapcache or because the swap entry indicates
3943 * exclusivity.
3944 */
3945 if (!folio_test_ksm(folio) &&
3946 (exclusive || folio_ref_count(folio) == 1)) {
3947 if (vmf->flags & FAULT_FLAG_WRITE) {
3948 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3949 vmf->flags &= ~FAULT_FLAG_WRITE;
3950 }
3951 rmap_flags |= RMAP_EXCLUSIVE;
3952 }
3953 flush_icache_page(vma, page);
3954 if (pte_swp_soft_dirty(vmf->orig_pte))
3955 pte = pte_mksoft_dirty(pte);
3956 if (pte_swp_uffd_wp(vmf->orig_pte)) {
3957 pte = pte_mkuffd_wp(pte);
3958 pte = pte_wrprotect(pte);
3959 }
3960 vmf->orig_pte = pte;
3961
3962 /* ksm created a completely new copy */
3963 if (unlikely(folio != swapcache && swapcache)) {
3964 page_add_new_anon_rmap(page, vma, vmf->address);
3965 folio_add_lru_vma(folio, vma);
3966 } else {
3967 page_add_anon_rmap(page, vma, vmf->address, rmap_flags);
3968 }
3969
3970 VM_BUG_ON(!folio_test_anon(folio) ||
3971 (pte_write(pte) && !PageAnonExclusive(page)));
3972 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3973 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3974
3975 folio_unlock(folio);
3976 if (folio != swapcache && swapcache) {
3977 /*
3978 * Hold the lock to avoid the swap entry to be reused
3979 * until we take the PT lock for the pte_same() check
3980 * (to avoid false positives from pte_same). For
3981 * further safety release the lock after the swap_free
3982 * so that the swap count won't change under a
3983 * parallel locked swapcache.
3984 */
3985 folio_unlock(swapcache);
3986 folio_put(swapcache);
3987 }
3988
3989 if (vmf->flags & FAULT_FLAG_WRITE) {
3990 ret |= do_wp_page(vmf);
3991 if (ret & VM_FAULT_ERROR)
3992 ret &= VM_FAULT_ERROR;
3993 goto out;
3994 }
3995
3996 /* No need to invalidate - it was non-present before */
3997 update_mmu_cache(vma, vmf->address, vmf->pte);
3998unlock:
3999 pte_unmap_unlock(vmf->pte, vmf->ptl);
4000out:
4001 if (si)
4002 put_swap_device(si);
4003 return ret;
4004out_nomap:
4005 pte_unmap_unlock(vmf->pte, vmf->ptl);
4006out_page:
4007 folio_unlock(folio);
4008out_release:
4009 folio_put(folio);
4010 if (folio != swapcache && swapcache) {
4011 folio_unlock(swapcache);
4012 folio_put(swapcache);
4013 }
4014 if (si)
4015 put_swap_device(si);
4016 return ret;
4017}
4018
4019/*
4020 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4021 * but allow concurrent faults), and pte mapped but not yet locked.
4022 * We return with mmap_lock still held, but pte unmapped and unlocked.
4023 */
4024static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
4025{
4026 struct vm_area_struct *vma = vmf->vma;
4027 struct page *page;
4028 vm_fault_t ret = 0;
4029 pte_t entry;
4030
4031 /* File mapping without ->vm_ops ? */
4032 if (vma->vm_flags & VM_SHARED)
4033 return VM_FAULT_SIGBUS;
4034
4035 /*
4036 * Use pte_alloc() instead of pte_alloc_map(). We can't run
4037 * pte_offset_map() on pmds where a huge pmd might be created
4038 * from a different thread.
4039 *
4040 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
4041 * parallel threads are excluded by other means.
4042 *
4043 * Here we only have mmap_read_lock(mm).
4044 */
4045 if (pte_alloc(vma->vm_mm, vmf->pmd))
4046 return VM_FAULT_OOM;
4047
4048 /* See comment in handle_pte_fault() */
4049 if (unlikely(pmd_trans_unstable(vmf->pmd)))
4050 return 0;
4051
4052 /* Use the zero-page for reads */
4053 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
4054 !mm_forbids_zeropage(vma->vm_mm)) {
4055 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
4056 vma->vm_page_prot));
4057 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4058 vmf->address, &vmf->ptl);
4059 if (!pte_none(*vmf->pte)) {
4060 update_mmu_tlb(vma, vmf->address, vmf->pte);
4061 goto unlock;
4062 }
4063 ret = check_stable_address_space(vma->vm_mm);
4064 if (ret)
4065 goto unlock;
4066 /* Deliver the page fault to userland, check inside PT lock */
4067 if (userfaultfd_missing(vma)) {
4068 pte_unmap_unlock(vmf->pte, vmf->ptl);
4069 return handle_userfault(vmf, VM_UFFD_MISSING);
4070 }
4071 goto setpte;
4072 }
4073
4074 /* Allocate our own private page. */
4075 if (unlikely(anon_vma_prepare(vma)))
4076 goto oom;
4077 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
4078 if (!page)
4079 goto oom;
4080
4081 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL))
4082 goto oom_free_page;
4083 cgroup_throttle_swaprate(page, GFP_KERNEL);
4084
4085 /*
4086 * The memory barrier inside __SetPageUptodate makes sure that
4087 * preceding stores to the page contents become visible before
4088 * the set_pte_at() write.
4089 */
4090 __SetPageUptodate(page);
4091
4092 entry = mk_pte(page, vma->vm_page_prot);
4093 entry = pte_sw_mkyoung(entry);
4094 if (vma->vm_flags & VM_WRITE)
4095 entry = pte_mkwrite(pte_mkdirty(entry));
4096
4097 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
4098 &vmf->ptl);
4099 if (!pte_none(*vmf->pte)) {
4100 update_mmu_tlb(vma, vmf->address, vmf->pte);
4101 goto release;
4102 }
4103
4104 ret = check_stable_address_space(vma->vm_mm);
4105 if (ret)
4106 goto release;
4107
4108 /* Deliver the page fault to userland, check inside PT lock */
4109 if (userfaultfd_missing(vma)) {
4110 pte_unmap_unlock(vmf->pte, vmf->ptl);
4111 put_page(page);
4112 return handle_userfault(vmf, VM_UFFD_MISSING);
4113 }
4114
4115 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
4116 page_add_new_anon_rmap(page, vma, vmf->address);
4117 lru_cache_add_inactive_or_unevictable(page, vma);
4118setpte:
4119 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
4120
4121 /* No need to invalidate - it was non-present before */
4122 update_mmu_cache(vma, vmf->address, vmf->pte);
4123unlock:
4124 pte_unmap_unlock(vmf->pte, vmf->ptl);
4125 return ret;
4126release:
4127 put_page(page);
4128 goto unlock;
4129oom_free_page:
4130 put_page(page);
4131oom:
4132 return VM_FAULT_OOM;
4133}
4134
4135/*
4136 * The mmap_lock must have been held on entry, and may have been
4137 * released depending on flags and vma->vm_ops->fault() return value.
4138 * See filemap_fault() and __lock_page_retry().
4139 */
4140static vm_fault_t __do_fault(struct vm_fault *vmf)
4141{
4142 struct vm_area_struct *vma = vmf->vma;
4143 vm_fault_t ret;
4144
4145 /*
4146 * Preallocate pte before we take page_lock because this might lead to
4147 * deadlocks for memcg reclaim which waits for pages under writeback:
4148 * lock_page(A)
4149 * SetPageWriteback(A)
4150 * unlock_page(A)
4151 * lock_page(B)
4152 * lock_page(B)
4153 * pte_alloc_one
4154 * shrink_page_list
4155 * wait_on_page_writeback(A)
4156 * SetPageWriteback(B)
4157 * unlock_page(B)
4158 * # flush A, B to clear the writeback
4159 */
4160 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
4161 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4162 if (!vmf->prealloc_pte)
4163 return VM_FAULT_OOM;
4164 }
4165
4166 ret = vma->vm_ops->fault(vmf);
4167 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
4168 VM_FAULT_DONE_COW)))
4169 return ret;
4170
4171 if (unlikely(PageHWPoison(vmf->page))) {
4172 struct page *page = vmf->page;
4173 vm_fault_t poisonret = VM_FAULT_HWPOISON;
4174 if (ret & VM_FAULT_LOCKED) {
4175 if (page_mapped(page))
4176 unmap_mapping_pages(page_mapping(page),
4177 page->index, 1, false);
4178 /* Retry if a clean page was removed from the cache. */
4179 if (invalidate_inode_page(page))
4180 poisonret = VM_FAULT_NOPAGE;
4181 unlock_page(page);
4182 }
4183 put_page(page);
4184 vmf->page = NULL;
4185 return poisonret;
4186 }
4187
4188 if (unlikely(!(ret & VM_FAULT_LOCKED)))
4189 lock_page(vmf->page);
4190 else
4191 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
4192
4193 return ret;
4194}
4195
4196#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4197static void deposit_prealloc_pte(struct vm_fault *vmf)
4198{
4199 struct vm_area_struct *vma = vmf->vma;
4200
4201 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
4202 /*
4203 * We are going to consume the prealloc table,
4204 * count that as nr_ptes.
4205 */
4206 mm_inc_nr_ptes(vma->vm_mm);
4207 vmf->prealloc_pte = NULL;
4208}
4209
4210vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4211{
4212 struct vm_area_struct *vma = vmf->vma;
4213 bool write = vmf->flags & FAULT_FLAG_WRITE;
4214 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
4215 pmd_t entry;
4216 int i;
4217 vm_fault_t ret = VM_FAULT_FALLBACK;
4218
4219 if (!transhuge_vma_suitable(vma, haddr))
4220 return ret;
4221
4222 page = compound_head(page);
4223 if (compound_order(page) != HPAGE_PMD_ORDER)
4224 return ret;
4225
4226 /*
4227 * Just backoff if any subpage of a THP is corrupted otherwise
4228 * the corrupted page may mapped by PMD silently to escape the
4229 * check. This kind of THP just can be PTE mapped. Access to
4230 * the corrupted subpage should trigger SIGBUS as expected.
4231 */
4232 if (unlikely(PageHasHWPoisoned(page)))
4233 return ret;
4234
4235 /*
4236 * Archs like ppc64 need additional space to store information
4237 * related to pte entry. Use the preallocated table for that.
4238 */
4239 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
4240 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4241 if (!vmf->prealloc_pte)
4242 return VM_FAULT_OOM;
4243 }
4244
4245 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4246 if (unlikely(!pmd_none(*vmf->pmd)))
4247 goto out;
4248
4249 for (i = 0; i < HPAGE_PMD_NR; i++)
4250 flush_icache_page(vma, page + i);
4251
4252 entry = mk_huge_pmd(page, vma->vm_page_prot);
4253 if (write)
4254 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
4255
4256 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
4257 page_add_file_rmap(page, vma, true);
4258
4259 /*
4260 * deposit and withdraw with pmd lock held
4261 */
4262 if (arch_needs_pgtable_deposit())
4263 deposit_prealloc_pte(vmf);
4264
4265 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
4266
4267 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
4268
4269 /* fault is handled */
4270 ret = 0;
4271 count_vm_event(THP_FILE_MAPPED);
4272out:
4273 spin_unlock(vmf->ptl);
4274 return ret;
4275}
4276#else
4277vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4278{
4279 return VM_FAULT_FALLBACK;
4280}
4281#endif
4282
4283void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
4284{
4285 struct vm_area_struct *vma = vmf->vma;
4286 bool uffd_wp = pte_marker_uffd_wp(vmf->orig_pte);
4287 bool write = vmf->flags & FAULT_FLAG_WRITE;
4288 bool prefault = vmf->address != addr;
4289 pte_t entry;
4290
4291 flush_icache_page(vma, page);
4292 entry = mk_pte(page, vma->vm_page_prot);
4293
4294 if (prefault && arch_wants_old_prefaulted_pte())
4295 entry = pte_mkold(entry);
4296 else
4297 entry = pte_sw_mkyoung(entry);
4298
4299 if (write)
4300 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
4301 if (unlikely(uffd_wp))
4302 entry = pte_mkuffd_wp(pte_wrprotect(entry));
4303 /* copy-on-write page */
4304 if (write && !(vma->vm_flags & VM_SHARED)) {
4305 inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
4306 page_add_new_anon_rmap(page, vma, addr);
4307 lru_cache_add_inactive_or_unevictable(page, vma);
4308 } else {
4309 inc_mm_counter(vma->vm_mm, mm_counter_file(page));
4310 page_add_file_rmap(page, vma, false);
4311 }
4312 set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
4313}
4314
4315static bool vmf_pte_changed(struct vm_fault *vmf)
4316{
4317 if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)
4318 return !pte_same(*vmf->pte, vmf->orig_pte);
4319
4320 return !pte_none(*vmf->pte);
4321}
4322
4323/**
4324 * finish_fault - finish page fault once we have prepared the page to fault
4325 *
4326 * @vmf: structure describing the fault
4327 *
4328 * This function handles all that is needed to finish a page fault once the
4329 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
4330 * given page, adds reverse page mapping, handles memcg charges and LRU
4331 * addition.
4332 *
4333 * The function expects the page to be locked and on success it consumes a
4334 * reference of a page being mapped (for the PTE which maps it).
4335 *
4336 * Return: %0 on success, %VM_FAULT_ code in case of error.
4337 */
4338vm_fault_t finish_fault(struct vm_fault *vmf)
4339{
4340 struct vm_area_struct *vma = vmf->vma;
4341 struct page *page;
4342 vm_fault_t ret;
4343
4344 /* Did we COW the page? */
4345 if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
4346 page = vmf->cow_page;
4347 else
4348 page = vmf->page;
4349
4350 /*
4351 * check even for read faults because we might have lost our CoWed
4352 * page
4353 */
4354 if (!(vma->vm_flags & VM_SHARED)) {
4355 ret = check_stable_address_space(vma->vm_mm);
4356 if (ret)
4357 return ret;
4358 }
4359
4360 if (pmd_none(*vmf->pmd)) {
4361 if (PageTransCompound(page)) {
4362 ret = do_set_pmd(vmf, page);
4363 if (ret != VM_FAULT_FALLBACK)
4364 return ret;
4365 }
4366
4367 if (vmf->prealloc_pte)
4368 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
4369 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
4370 return VM_FAULT_OOM;
4371 }
4372
4373 /*
4374 * See comment in handle_pte_fault() for how this scenario happens, we
4375 * need to return NOPAGE so that we drop this page.
4376 */
4377 if (pmd_devmap_trans_unstable(vmf->pmd))
4378 return VM_FAULT_NOPAGE;
4379
4380 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4381 vmf->address, &vmf->ptl);
4382
4383 /* Re-check under ptl */
4384 if (likely(!vmf_pte_changed(vmf))) {
4385 do_set_pte(vmf, page, vmf->address);
4386
4387 /* no need to invalidate: a not-present page won't be cached */
4388 update_mmu_cache(vma, vmf->address, vmf->pte);
4389
4390 ret = 0;
4391 } else {
4392 update_mmu_tlb(vma, vmf->address, vmf->pte);
4393 ret = VM_FAULT_NOPAGE;
4394 }
4395
4396 pte_unmap_unlock(vmf->pte, vmf->ptl);
4397 return ret;
4398}
4399
4400static unsigned long fault_around_bytes __read_mostly =
4401 rounddown_pow_of_two(65536);
4402
4403#ifdef CONFIG_DEBUG_FS
4404static int fault_around_bytes_get(void *data, u64 *val)
4405{
4406 *val = fault_around_bytes;
4407 return 0;
4408}
4409
4410/*
4411 * fault_around_bytes must be rounded down to the nearest page order as it's
4412 * what do_fault_around() expects to see.
4413 */
4414static int fault_around_bytes_set(void *data, u64 val)
4415{
4416 if (val / PAGE_SIZE > PTRS_PER_PTE)
4417 return -EINVAL;
4418 if (val > PAGE_SIZE)
4419 fault_around_bytes = rounddown_pow_of_two(val);
4420 else
4421 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
4422 return 0;
4423}
4424DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
4425 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
4426
4427static int __init fault_around_debugfs(void)
4428{
4429 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
4430 &fault_around_bytes_fops);
4431 return 0;
4432}
4433late_initcall(fault_around_debugfs);
4434#endif
4435
4436/*
4437 * do_fault_around() tries to map few pages around the fault address. The hope
4438 * is that the pages will be needed soon and this will lower the number of
4439 * faults to handle.
4440 *
4441 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
4442 * not ready to be mapped: not up-to-date, locked, etc.
4443 *
4444 * This function doesn't cross the VMA boundaries, in order to call map_pages()
4445 * only once.
4446 *
4447 * fault_around_bytes defines how many bytes we'll try to map.
4448 * do_fault_around() expects it to be set to a power of two less than or equal
4449 * to PTRS_PER_PTE.
4450 *
4451 * The virtual address of the area that we map is naturally aligned to
4452 * fault_around_bytes rounded down to the machine page size
4453 * (and therefore to page order). This way it's easier to guarantee
4454 * that we don't cross page table boundaries.
4455 */
4456static vm_fault_t do_fault_around(struct vm_fault *vmf)
4457{
4458 unsigned long address = vmf->address, nr_pages, mask;
4459 pgoff_t start_pgoff = vmf->pgoff;
4460 pgoff_t end_pgoff;
4461 int off;
4462
4463 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
4464 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
4465
4466 address = max(address & mask, vmf->vma->vm_start);
4467 off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
4468 start_pgoff -= off;
4469
4470 /*
4471 * end_pgoff is either the end of the page table, the end of
4472 * the vma or nr_pages from start_pgoff, depending what is nearest.
4473 */
4474 end_pgoff = start_pgoff -
4475 ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
4476 PTRS_PER_PTE - 1;
4477 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
4478 start_pgoff + nr_pages - 1);
4479
4480 if (pmd_none(*vmf->pmd)) {
4481 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
4482 if (!vmf->prealloc_pte)
4483 return VM_FAULT_OOM;
4484 }
4485
4486 return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
4487}
4488
4489/* Return true if we should do read fault-around, false otherwise */
4490static inline bool should_fault_around(struct vm_fault *vmf)
4491{
4492 /* No ->map_pages? No way to fault around... */
4493 if (!vmf->vma->vm_ops->map_pages)
4494 return false;
4495
4496 if (uffd_disable_fault_around(vmf->vma))
4497 return false;
4498
4499 return fault_around_bytes >> PAGE_SHIFT > 1;
4500}
4501
4502static vm_fault_t do_read_fault(struct vm_fault *vmf)
4503{
4504 vm_fault_t ret = 0;
4505
4506 /*
4507 * Let's call ->map_pages() first and use ->fault() as fallback
4508 * if page by the offset is not ready to be mapped (cold cache or
4509 * something).
4510 */
4511 if (should_fault_around(vmf)) {
4512 ret = do_fault_around(vmf);
4513 if (ret)
4514 return ret;
4515 }
4516
4517 ret = __do_fault(vmf);
4518 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4519 return ret;
4520
4521 ret |= finish_fault(vmf);
4522 unlock_page(vmf->page);
4523 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4524 put_page(vmf->page);
4525 return ret;
4526}
4527
4528static vm_fault_t do_cow_fault(struct vm_fault *vmf)
4529{
4530 struct vm_area_struct *vma = vmf->vma;
4531 vm_fault_t ret;
4532
4533 if (unlikely(anon_vma_prepare(vma)))
4534 return VM_FAULT_OOM;
4535
4536 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
4537 if (!vmf->cow_page)
4538 return VM_FAULT_OOM;
4539
4540 if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm,
4541 GFP_KERNEL)) {
4542 put_page(vmf->cow_page);
4543 return VM_FAULT_OOM;
4544 }
4545 cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL);
4546
4547 ret = __do_fault(vmf);
4548 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4549 goto uncharge_out;
4550 if (ret & VM_FAULT_DONE_COW)
4551 return ret;
4552
4553 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
4554 __SetPageUptodate(vmf->cow_page);
4555
4556 ret |= finish_fault(vmf);
4557 unlock_page(vmf->page);
4558 put_page(vmf->page);
4559 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4560 goto uncharge_out;
4561 return ret;
4562uncharge_out:
4563 put_page(vmf->cow_page);
4564 return ret;
4565}
4566
4567static vm_fault_t do_shared_fault(struct vm_fault *vmf)
4568{
4569 struct vm_area_struct *vma = vmf->vma;
4570 vm_fault_t ret, tmp;
4571
4572 ret = __do_fault(vmf);
4573 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4574 return ret;
4575
4576 /*
4577 * Check if the backing address space wants to know that the page is
4578 * about to become writable
4579 */
4580 if (vma->vm_ops->page_mkwrite) {
4581 unlock_page(vmf->page);
4582 tmp = do_page_mkwrite(vmf);
4583 if (unlikely(!tmp ||
4584 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
4585 put_page(vmf->page);
4586 return tmp;
4587 }
4588 }
4589
4590 ret |= finish_fault(vmf);
4591 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
4592 VM_FAULT_RETRY))) {
4593 unlock_page(vmf->page);
4594 put_page(vmf->page);
4595 return ret;
4596 }
4597
4598 ret |= fault_dirty_shared_page(vmf);
4599 return ret;
4600}
4601
4602/*
4603 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4604 * but allow concurrent faults).
4605 * The mmap_lock may have been released depending on flags and our
4606 * return value. See filemap_fault() and __folio_lock_or_retry().
4607 * If mmap_lock is released, vma may become invalid (for example
4608 * by other thread calling munmap()).
4609 */
4610static vm_fault_t do_fault(struct vm_fault *vmf)
4611{
4612 struct vm_area_struct *vma = vmf->vma;
4613 struct mm_struct *vm_mm = vma->vm_mm;
4614 vm_fault_t ret;
4615
4616 /*
4617 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4618 */
4619 if (!vma->vm_ops->fault) {
4620 /*
4621 * If we find a migration pmd entry or a none pmd entry, which
4622 * should never happen, return SIGBUS
4623 */
4624 if (unlikely(!pmd_present(*vmf->pmd)))
4625 ret = VM_FAULT_SIGBUS;
4626 else {
4627 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
4628 vmf->pmd,
4629 vmf->address,
4630 &vmf->ptl);
4631 /*
4632 * Make sure this is not a temporary clearing of pte
4633 * by holding ptl and checking again. A R/M/W update
4634 * of pte involves: take ptl, clearing the pte so that
4635 * we don't have concurrent modification by hardware
4636 * followed by an update.
4637 */
4638 if (unlikely(pte_none(*vmf->pte)))
4639 ret = VM_FAULT_SIGBUS;
4640 else
4641 ret = VM_FAULT_NOPAGE;
4642
4643 pte_unmap_unlock(vmf->pte, vmf->ptl);
4644 }
4645 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
4646 ret = do_read_fault(vmf);
4647 else if (!(vma->vm_flags & VM_SHARED))
4648 ret = do_cow_fault(vmf);
4649 else
4650 ret = do_shared_fault(vmf);
4651
4652 /* preallocated pagetable is unused: free it */
4653 if (vmf->prealloc_pte) {
4654 pte_free(vm_mm, vmf->prealloc_pte);
4655 vmf->prealloc_pte = NULL;
4656 }
4657 return ret;
4658}
4659
4660int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
4661 unsigned long addr, int page_nid, int *flags)
4662{
4663 get_page(page);
4664
4665 count_vm_numa_event(NUMA_HINT_FAULTS);
4666 if (page_nid == numa_node_id()) {
4667 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
4668 *flags |= TNF_FAULT_LOCAL;
4669 }
4670
4671 return mpol_misplaced(page, vma, addr);
4672}
4673
4674static vm_fault_t do_numa_page(struct vm_fault *vmf)
4675{
4676 struct vm_area_struct *vma = vmf->vma;
4677 struct page *page = NULL;
4678 int page_nid = NUMA_NO_NODE;
4679 bool writable = false;
4680 int last_cpupid;
4681 int target_nid;
4682 pte_t pte, old_pte;
4683 int flags = 0;
4684
4685 /*
4686 * The "pte" at this point cannot be used safely without
4687 * validation through pte_unmap_same(). It's of NUMA type but
4688 * the pfn may be screwed if the read is non atomic.
4689 */
4690 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
4691 spin_lock(vmf->ptl);
4692 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4693 pte_unmap_unlock(vmf->pte, vmf->ptl);
4694 goto out;
4695 }
4696
4697 /* Get the normal PTE */
4698 old_pte = ptep_get(vmf->pte);
4699 pte = pte_modify(old_pte, vma->vm_page_prot);
4700
4701 /*
4702 * Detect now whether the PTE could be writable; this information
4703 * is only valid while holding the PT lock.
4704 */
4705 writable = pte_write(pte);
4706 if (!writable && vma_wants_manual_pte_write_upgrade(vma) &&
4707 can_change_pte_writable(vma, vmf->address, pte))
4708 writable = true;
4709
4710 page = vm_normal_page(vma, vmf->address, pte);
4711 if (!page || is_zone_device_page(page))
4712 goto out_map;
4713
4714 /* TODO: handle PTE-mapped THP */
4715 if (PageCompound(page))
4716 goto out_map;
4717
4718 /*
4719 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4720 * much anyway since they can be in shared cache state. This misses
4721 * the case where a mapping is writable but the process never writes
4722 * to it but pte_write gets cleared during protection updates and
4723 * pte_dirty has unpredictable behaviour between PTE scan updates,
4724 * background writeback, dirty balancing and application behaviour.
4725 */
4726 if (!writable)
4727 flags |= TNF_NO_GROUP;
4728
4729 /*
4730 * Flag if the page is shared between multiple address spaces. This
4731 * is later used when determining whether to group tasks together
4732 */
4733 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
4734 flags |= TNF_SHARED;
4735
4736 page_nid = page_to_nid(page);
4737 /*
4738 * For memory tiering mode, cpupid of slow memory page is used
4739 * to record page access time. So use default value.
4740 */
4741 if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
4742 !node_is_toptier(page_nid))
4743 last_cpupid = (-1 & LAST_CPUPID_MASK);
4744 else
4745 last_cpupid = page_cpupid_last(page);
4746 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
4747 &flags);
4748 if (target_nid == NUMA_NO_NODE) {
4749 put_page(page);
4750 goto out_map;
4751 }
4752 pte_unmap_unlock(vmf->pte, vmf->ptl);
4753 writable = false;
4754
4755 /* Migrate to the requested node */
4756 if (migrate_misplaced_page(page, vma, target_nid)) {
4757 page_nid = target_nid;
4758 flags |= TNF_MIGRATED;
4759 } else {
4760 flags |= TNF_MIGRATE_FAIL;
4761 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4762 spin_lock(vmf->ptl);
4763 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4764 pte_unmap_unlock(vmf->pte, vmf->ptl);
4765 goto out;
4766 }
4767 goto out_map;
4768 }
4769
4770out:
4771 if (page_nid != NUMA_NO_NODE)
4772 task_numa_fault(last_cpupid, page_nid, 1, flags);
4773 return 0;
4774out_map:
4775 /*
4776 * Make it present again, depending on how arch implements
4777 * non-accessible ptes, some can allow access by kernel mode.
4778 */
4779 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
4780 pte = pte_modify(old_pte, vma->vm_page_prot);
4781 pte = pte_mkyoung(pte);
4782 if (writable)
4783 pte = pte_mkwrite(pte);
4784 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
4785 update_mmu_cache(vma, vmf->address, vmf->pte);
4786 pte_unmap_unlock(vmf->pte, vmf->ptl);
4787 goto out;
4788}
4789
4790static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
4791{
4792 if (vma_is_anonymous(vmf->vma))
4793 return do_huge_pmd_anonymous_page(vmf);
4794 if (vmf->vma->vm_ops->huge_fault)
4795 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4796 return VM_FAULT_FALLBACK;
4797}
4798
4799/* `inline' is required to avoid gcc 4.1.2 build error */
4800static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
4801{
4802 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
4803 vm_fault_t ret;
4804
4805 if (vma_is_anonymous(vmf->vma)) {
4806 if (likely(!unshare) &&
4807 userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd))
4808 return handle_userfault(vmf, VM_UFFD_WP);
4809 return do_huge_pmd_wp_page(vmf);
4810 }
4811
4812 if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
4813 if (vmf->vma->vm_ops->huge_fault) {
4814 ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4815 if (!(ret & VM_FAULT_FALLBACK))
4816 return ret;
4817 }
4818 }
4819
4820 /* COW or write-notify handled on pte level: split pmd. */
4821 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
4822
4823 return VM_FAULT_FALLBACK;
4824}
4825
4826static vm_fault_t create_huge_pud(struct vm_fault *vmf)
4827{
4828#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4829 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4830 /* No support for anonymous transparent PUD pages yet */
4831 if (vma_is_anonymous(vmf->vma))
4832 return VM_FAULT_FALLBACK;
4833 if (vmf->vma->vm_ops->huge_fault)
4834 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4835#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4836 return VM_FAULT_FALLBACK;
4837}
4838
4839static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
4840{
4841#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4842 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4843 vm_fault_t ret;
4844
4845 /* No support for anonymous transparent PUD pages yet */
4846 if (vma_is_anonymous(vmf->vma))
4847 goto split;
4848 if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
4849 if (vmf->vma->vm_ops->huge_fault) {
4850 ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4851 if (!(ret & VM_FAULT_FALLBACK))
4852 return ret;
4853 }
4854 }
4855split:
4856 /* COW or write-notify not handled on PUD level: split pud.*/
4857 __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
4858#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
4859 return VM_FAULT_FALLBACK;
4860}
4861
4862/*
4863 * These routines also need to handle stuff like marking pages dirty
4864 * and/or accessed for architectures that don't do it in hardware (most
4865 * RISC architectures). The early dirtying is also good on the i386.
4866 *
4867 * There is also a hook called "update_mmu_cache()" that architectures
4868 * with external mmu caches can use to update those (ie the Sparc or
4869 * PowerPC hashed page tables that act as extended TLBs).
4870 *
4871 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
4872 * concurrent faults).
4873 *
4874 * The mmap_lock may have been released depending on flags and our return value.
4875 * See filemap_fault() and __folio_lock_or_retry().
4876 */
4877static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
4878{
4879 pte_t entry;
4880
4881 if (unlikely(pmd_none(*vmf->pmd))) {
4882 /*
4883 * Leave __pte_alloc() until later: because vm_ops->fault may
4884 * want to allocate huge page, and if we expose page table
4885 * for an instant, it will be difficult to retract from
4886 * concurrent faults and from rmap lookups.
4887 */
4888 vmf->pte = NULL;
4889 vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID;
4890 } else {
4891 /*
4892 * If a huge pmd materialized under us just retry later. Use
4893 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead
4894 * of pmd_trans_huge() to ensure the pmd didn't become
4895 * pmd_trans_huge under us and then back to pmd_none, as a
4896 * result of MADV_DONTNEED running immediately after a huge pmd
4897 * fault in a different thread of this mm, in turn leading to a
4898 * misleading pmd_trans_huge() retval. All we have to ensure is
4899 * that it is a regular pmd that we can walk with
4900 * pte_offset_map() and we can do that through an atomic read
4901 * in C, which is what pmd_trans_unstable() provides.
4902 */
4903 if (pmd_devmap_trans_unstable(vmf->pmd))
4904 return 0;
4905 /*
4906 * A regular pmd is established and it can't morph into a huge
4907 * pmd from under us anymore at this point because we hold the
4908 * mmap_lock read mode and khugepaged takes it in write mode.
4909 * So now it's safe to run pte_offset_map().
4910 */
4911 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4912 vmf->orig_pte = *vmf->pte;
4913 vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID;
4914
4915 /*
4916 * some architectures can have larger ptes than wordsize,
4917 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4918 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4919 * accesses. The code below just needs a consistent view
4920 * for the ifs and we later double check anyway with the
4921 * ptl lock held. So here a barrier will do.
4922 */
4923 barrier();
4924 if (pte_none(vmf->orig_pte)) {
4925 pte_unmap(vmf->pte);
4926 vmf->pte = NULL;
4927 }
4928 }
4929
4930 if (!vmf->pte) {
4931 if (vma_is_anonymous(vmf->vma))
4932 return do_anonymous_page(vmf);
4933 else
4934 return do_fault(vmf);
4935 }
4936
4937 if (!pte_present(vmf->orig_pte))
4938 return do_swap_page(vmf);
4939
4940 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
4941 return do_numa_page(vmf);
4942
4943 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
4944 spin_lock(vmf->ptl);
4945 entry = vmf->orig_pte;
4946 if (unlikely(!pte_same(*vmf->pte, entry))) {
4947 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
4948 goto unlock;
4949 }
4950 if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
4951 if (!pte_write(entry))
4952 return do_wp_page(vmf);
4953 else if (likely(vmf->flags & FAULT_FLAG_WRITE))
4954 entry = pte_mkdirty(entry);
4955 }
4956 entry = pte_mkyoung(entry);
4957 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
4958 vmf->flags & FAULT_FLAG_WRITE)) {
4959 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
4960 } else {
4961 /* Skip spurious TLB flush for retried page fault */
4962 if (vmf->flags & FAULT_FLAG_TRIED)
4963 goto unlock;
4964 /*
4965 * This is needed only for protection faults but the arch code
4966 * is not yet telling us if this is a protection fault or not.
4967 * This still avoids useless tlb flushes for .text page faults
4968 * with threads.
4969 */
4970 if (vmf->flags & FAULT_FLAG_WRITE)
4971 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
4972 }
4973unlock:
4974 pte_unmap_unlock(vmf->pte, vmf->ptl);
4975 return 0;
4976}
4977
4978/*
4979 * By the time we get here, we already hold the mm semaphore
4980 *
4981 * The mmap_lock may have been released depending on flags and our
4982 * return value. See filemap_fault() and __folio_lock_or_retry().
4983 */
4984static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
4985 unsigned long address, unsigned int flags)
4986{
4987 struct vm_fault vmf = {
4988 .vma = vma,
4989 .address = address & PAGE_MASK,
4990 .real_address = address,
4991 .flags = flags,
4992 .pgoff = linear_page_index(vma, address),
4993 .gfp_mask = __get_fault_gfp_mask(vma),
4994 };
4995 struct mm_struct *mm = vma->vm_mm;
4996 unsigned long vm_flags = vma->vm_flags;
4997 pgd_t *pgd;
4998 p4d_t *p4d;
4999 vm_fault_t ret;
5000
5001 pgd = pgd_offset(mm, address);
5002 p4d = p4d_alloc(mm, pgd, address);
5003 if (!p4d)
5004 return VM_FAULT_OOM;
5005
5006 vmf.pud = pud_alloc(mm, p4d, address);
5007 if (!vmf.pud)
5008 return VM_FAULT_OOM;
5009retry_pud:
5010 if (pud_none(*vmf.pud) &&
5011 hugepage_vma_check(vma, vm_flags, false, true, true)) {
5012 ret = create_huge_pud(&vmf);
5013 if (!(ret & VM_FAULT_FALLBACK))
5014 return ret;
5015 } else {
5016 pud_t orig_pud = *vmf.pud;
5017
5018 barrier();
5019 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
5020
5021 /*
5022 * TODO once we support anonymous PUDs: NUMA case and
5023 * FAULT_FLAG_UNSHARE handling.
5024 */
5025 if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) {
5026 ret = wp_huge_pud(&vmf, orig_pud);
5027 if (!(ret & VM_FAULT_FALLBACK))
5028 return ret;
5029 } else {
5030 huge_pud_set_accessed(&vmf, orig_pud);
5031 return 0;
5032 }
5033 }
5034 }
5035
5036 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
5037 if (!vmf.pmd)
5038 return VM_FAULT_OOM;
5039
5040 /* Huge pud page fault raced with pmd_alloc? */
5041 if (pud_trans_unstable(vmf.pud))
5042 goto retry_pud;
5043
5044 if (pmd_none(*vmf.pmd) &&
5045 hugepage_vma_check(vma, vm_flags, false, true, true)) {
5046 ret = create_huge_pmd(&vmf);
5047 if (!(ret & VM_FAULT_FALLBACK))
5048 return ret;
5049 } else {
5050 vmf.orig_pmd = *vmf.pmd;
5051
5052 barrier();
5053 if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
5054 VM_BUG_ON(thp_migration_supported() &&
5055 !is_pmd_migration_entry(vmf.orig_pmd));
5056 if (is_pmd_migration_entry(vmf.orig_pmd))
5057 pmd_migration_entry_wait(mm, vmf.pmd);
5058 return 0;
5059 }
5060 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
5061 if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
5062 return do_huge_pmd_numa_page(&vmf);
5063
5064 if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
5065 !pmd_write(vmf.orig_pmd)) {
5066 ret = wp_huge_pmd(&vmf);
5067 if (!(ret & VM_FAULT_FALLBACK))
5068 return ret;
5069 } else {
5070 huge_pmd_set_accessed(&vmf);
5071 return 0;
5072 }
5073 }
5074 }
5075
5076 return handle_pte_fault(&vmf);
5077}
5078
5079/**
5080 * mm_account_fault - Do page fault accounting
5081 *
5082 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
5083 * of perf event counters, but we'll still do the per-task accounting to
5084 * the task who triggered this page fault.
5085 * @address: the faulted address.
5086 * @flags: the fault flags.
5087 * @ret: the fault retcode.
5088 *
5089 * This will take care of most of the page fault accounting. Meanwhile, it
5090 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
5091 * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
5092 * still be in per-arch page fault handlers at the entry of page fault.
5093 */
5094static inline void mm_account_fault(struct pt_regs *regs,
5095 unsigned long address, unsigned int flags,
5096 vm_fault_t ret)
5097{
5098 bool major;
5099
5100 /*
5101 * We don't do accounting for some specific faults:
5102 *
5103 * - Unsuccessful faults (e.g. when the address wasn't valid). That
5104 * includes arch_vma_access_permitted() failing before reaching here.
5105 * So this is not a "this many hardware page faults" counter. We
5106 * should use the hw profiling for that.
5107 *
5108 * - Incomplete faults (VM_FAULT_RETRY). They will only be counted
5109 * once they're completed.
5110 */
5111 if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
5112 return;
5113
5114 /*
5115 * We define the fault as a major fault when the final successful fault
5116 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
5117 * handle it immediately previously).
5118 */
5119 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
5120
5121 if (major)
5122 current->maj_flt++;
5123 else
5124 current->min_flt++;
5125
5126 /*
5127 * If the fault is done for GUP, regs will be NULL. We only do the
5128 * accounting for the per thread fault counters who triggered the
5129 * fault, and we skip the perf event updates.
5130 */
5131 if (!regs)
5132 return;
5133
5134 if (major)
5135 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
5136 else
5137 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
5138}
5139
5140#ifdef CONFIG_LRU_GEN
5141static void lru_gen_enter_fault(struct vm_area_struct *vma)
5142{
5143 /* the LRU algorithm doesn't apply to sequential or random reads */
5144 current->in_lru_fault = !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ));
5145}
5146
5147static void lru_gen_exit_fault(void)
5148{
5149 current->in_lru_fault = false;
5150}
5151#else
5152static void lru_gen_enter_fault(struct vm_area_struct *vma)
5153{
5154}
5155
5156static void lru_gen_exit_fault(void)
5157{
5158}
5159#endif /* CONFIG_LRU_GEN */
5160
5161static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma,
5162 unsigned int *flags)
5163{
5164 if (unlikely(*flags & FAULT_FLAG_UNSHARE)) {
5165 if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE))
5166 return VM_FAULT_SIGSEGV;
5167 /*
5168 * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's
5169 * just treat it like an ordinary read-fault otherwise.
5170 */
5171 if (!is_cow_mapping(vma->vm_flags))
5172 *flags &= ~FAULT_FLAG_UNSHARE;
5173 } else if (*flags & FAULT_FLAG_WRITE) {
5174 /* Write faults on read-only mappings are impossible ... */
5175 if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE)))
5176 return VM_FAULT_SIGSEGV;
5177 /* ... and FOLL_FORCE only applies to COW mappings. */
5178 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) &&
5179 !is_cow_mapping(vma->vm_flags)))
5180 return VM_FAULT_SIGSEGV;
5181 }
5182 return 0;
5183}
5184
5185/*
5186 * By the time we get here, we already hold the mm semaphore
5187 *
5188 * The mmap_lock may have been released depending on flags and our
5189 * return value. See filemap_fault() and __folio_lock_or_retry().
5190 */
5191vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
5192 unsigned int flags, struct pt_regs *regs)
5193{
5194 vm_fault_t ret;
5195
5196 __set_current_state(TASK_RUNNING);
5197
5198 count_vm_event(PGFAULT);
5199 count_memcg_event_mm(vma->vm_mm, PGFAULT);
5200
5201 ret = sanitize_fault_flags(vma, &flags);
5202 if (ret)
5203 return ret;
5204
5205 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
5206 flags & FAULT_FLAG_INSTRUCTION,
5207 flags & FAULT_FLAG_REMOTE))
5208 return VM_FAULT_SIGSEGV;
5209
5210 /*
5211 * Enable the memcg OOM handling for faults triggered in user
5212 * space. Kernel faults are handled more gracefully.
5213 */
5214 if (flags & FAULT_FLAG_USER)
5215 mem_cgroup_enter_user_fault();
5216
5217 lru_gen_enter_fault(vma);
5218
5219 if (unlikely(is_vm_hugetlb_page(vma)))
5220 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
5221 else
5222 ret = __handle_mm_fault(vma, address, flags);
5223
5224 lru_gen_exit_fault();
5225
5226 if (flags & FAULT_FLAG_USER) {
5227 mem_cgroup_exit_user_fault();
5228 /*
5229 * The task may have entered a memcg OOM situation but
5230 * if the allocation error was handled gracefully (no
5231 * VM_FAULT_OOM), there is no need to kill anything.
5232 * Just clean up the OOM state peacefully.
5233 */
5234 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
5235 mem_cgroup_oom_synchronize(false);
5236 }
5237
5238 mm_account_fault(regs, address, flags, ret);
5239
5240 return ret;
5241}
5242EXPORT_SYMBOL_GPL(handle_mm_fault);
5243
5244#ifndef __PAGETABLE_P4D_FOLDED
5245/*
5246 * Allocate p4d page table.
5247 * We've already handled the fast-path in-line.
5248 */
5249int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
5250{
5251 p4d_t *new = p4d_alloc_one(mm, address);
5252 if (!new)
5253 return -ENOMEM;
5254
5255 spin_lock(&mm->page_table_lock);
5256 if (pgd_present(*pgd)) { /* Another has populated it */
5257 p4d_free(mm, new);
5258 } else {
5259 smp_wmb(); /* See comment in pmd_install() */
5260 pgd_populate(mm, pgd, new);
5261 }
5262 spin_unlock(&mm->page_table_lock);
5263 return 0;
5264}
5265#endif /* __PAGETABLE_P4D_FOLDED */
5266
5267#ifndef __PAGETABLE_PUD_FOLDED
5268/*
5269 * Allocate page upper directory.
5270 * We've already handled the fast-path in-line.
5271 */
5272int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
5273{
5274 pud_t *new = pud_alloc_one(mm, address);
5275 if (!new)
5276 return -ENOMEM;
5277
5278 spin_lock(&mm->page_table_lock);
5279 if (!p4d_present(*p4d)) {
5280 mm_inc_nr_puds(mm);
5281 smp_wmb(); /* See comment in pmd_install() */
5282 p4d_populate(mm, p4d, new);
5283 } else /* Another has populated it */
5284 pud_free(mm, new);
5285 spin_unlock(&mm->page_table_lock);
5286 return 0;
5287}
5288#endif /* __PAGETABLE_PUD_FOLDED */
5289
5290#ifndef __PAGETABLE_PMD_FOLDED
5291/*
5292 * Allocate page middle directory.
5293 * We've already handled the fast-path in-line.
5294 */
5295int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
5296{
5297 spinlock_t *ptl;
5298 pmd_t *new = pmd_alloc_one(mm, address);
5299 if (!new)
5300 return -ENOMEM;
5301
5302 ptl = pud_lock(mm, pud);
5303 if (!pud_present(*pud)) {
5304 mm_inc_nr_pmds(mm);
5305 smp_wmb(); /* See comment in pmd_install() */
5306 pud_populate(mm, pud, new);
5307 } else { /* Another has populated it */
5308 pmd_free(mm, new);
5309 }
5310 spin_unlock(ptl);
5311 return 0;
5312}
5313#endif /* __PAGETABLE_PMD_FOLDED */
5314
5315/**
5316 * follow_pte - look up PTE at a user virtual address
5317 * @mm: the mm_struct of the target address space
5318 * @address: user virtual address
5319 * @ptepp: location to store found PTE
5320 * @ptlp: location to store the lock for the PTE
5321 *
5322 * On a successful return, the pointer to the PTE is stored in @ptepp;
5323 * the corresponding lock is taken and its location is stored in @ptlp.
5324 * The contents of the PTE are only stable until @ptlp is released;
5325 * any further use, if any, must be protected against invalidation
5326 * with MMU notifiers.
5327 *
5328 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
5329 * should be taken for read.
5330 *
5331 * KVM uses this function. While it is arguably less bad than ``follow_pfn``,
5332 * it is not a good general-purpose API.
5333 *
5334 * Return: zero on success, -ve otherwise.
5335 */
5336int follow_pte(struct mm_struct *mm, unsigned long address,
5337 pte_t **ptepp, spinlock_t **ptlp)
5338{
5339 pgd_t *pgd;
5340 p4d_t *p4d;
5341 pud_t *pud;
5342 pmd_t *pmd;
5343 pte_t *ptep;
5344
5345 pgd = pgd_offset(mm, address);
5346 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
5347 goto out;
5348
5349 p4d = p4d_offset(pgd, address);
5350 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
5351 goto out;
5352
5353 pud = pud_offset(p4d, address);
5354 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
5355 goto out;
5356
5357 pmd = pmd_offset(pud, address);
5358 VM_BUG_ON(pmd_trans_huge(*pmd));
5359
5360 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
5361 goto out;
5362
5363 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
5364 if (!pte_present(*ptep))
5365 goto unlock;
5366 *ptepp = ptep;
5367 return 0;
5368unlock:
5369 pte_unmap_unlock(ptep, *ptlp);
5370out:
5371 return -EINVAL;
5372}
5373EXPORT_SYMBOL_GPL(follow_pte);
5374
5375/**
5376 * follow_pfn - look up PFN at a user virtual address
5377 * @vma: memory mapping
5378 * @address: user virtual address
5379 * @pfn: location to store found PFN
5380 *
5381 * Only IO mappings and raw PFN mappings are allowed.
5382 *
5383 * This function does not allow the caller to read the permissions
5384 * of the PTE. Do not use it.
5385 *
5386 * Return: zero and the pfn at @pfn on success, -ve otherwise.
5387 */
5388int follow_pfn(struct vm_area_struct *vma, unsigned long address,
5389 unsigned long *pfn)
5390{
5391 int ret = -EINVAL;
5392 spinlock_t *ptl;
5393 pte_t *ptep;
5394
5395 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5396 return ret;
5397
5398 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
5399 if (ret)
5400 return ret;
5401 *pfn = pte_pfn(*ptep);
5402 pte_unmap_unlock(ptep, ptl);
5403 return 0;
5404}
5405EXPORT_SYMBOL(follow_pfn);
5406
5407#ifdef CONFIG_HAVE_IOREMAP_PROT
5408int follow_phys(struct vm_area_struct *vma,
5409 unsigned long address, unsigned int flags,
5410 unsigned long *prot, resource_size_t *phys)
5411{
5412 int ret = -EINVAL;
5413 pte_t *ptep, pte;
5414 spinlock_t *ptl;
5415
5416 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5417 goto out;
5418
5419 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
5420 goto out;
5421 pte = *ptep;
5422
5423 if ((flags & FOLL_WRITE) && !pte_write(pte))
5424 goto unlock;
5425
5426 *prot = pgprot_val(pte_pgprot(pte));
5427 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5428
5429 ret = 0;
5430unlock:
5431 pte_unmap_unlock(ptep, ptl);
5432out:
5433 return ret;
5434}
5435
5436/**
5437 * generic_access_phys - generic implementation for iomem mmap access
5438 * @vma: the vma to access
5439 * @addr: userspace address, not relative offset within @vma
5440 * @buf: buffer to read/write
5441 * @len: length of transfer
5442 * @write: set to FOLL_WRITE when writing, otherwise reading
5443 *
5444 * This is a generic implementation for &vm_operations_struct.access for an
5445 * iomem mapping. This callback is used by access_process_vm() when the @vma is
5446 * not page based.
5447 */
5448int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
5449 void *buf, int len, int write)
5450{
5451 resource_size_t phys_addr;
5452 unsigned long prot = 0;
5453 void __iomem *maddr;
5454 pte_t *ptep, pte;
5455 spinlock_t *ptl;
5456 int offset = offset_in_page(addr);
5457 int ret = -EINVAL;
5458
5459 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
5460 return -EINVAL;
5461
5462retry:
5463 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5464 return -EINVAL;
5465 pte = *ptep;
5466 pte_unmap_unlock(ptep, ptl);
5467
5468 prot = pgprot_val(pte_pgprot(pte));
5469 phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
5470
5471 if ((write & FOLL_WRITE) && !pte_write(pte))
5472 return -EINVAL;
5473
5474 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
5475 if (!maddr)
5476 return -ENOMEM;
5477
5478 if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
5479 goto out_unmap;
5480
5481 if (!pte_same(pte, *ptep)) {
5482 pte_unmap_unlock(ptep, ptl);
5483 iounmap(maddr);
5484
5485 goto retry;
5486 }
5487
5488 if (write)
5489 memcpy_toio(maddr + offset, buf, len);
5490 else
5491 memcpy_fromio(buf, maddr + offset, len);
5492 ret = len;
5493 pte_unmap_unlock(ptep, ptl);
5494out_unmap:
5495 iounmap(maddr);
5496
5497 return ret;
5498}
5499EXPORT_SYMBOL_GPL(generic_access_phys);
5500#endif
5501
5502/*
5503 * Access another process' address space as given in mm.
5504 */
5505int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
5506 int len, unsigned int gup_flags)
5507{
5508 struct vm_area_struct *vma;
5509 void *old_buf = buf;
5510 int write = gup_flags & FOLL_WRITE;
5511
5512 if (mmap_read_lock_killable(mm))
5513 return 0;
5514
5515 /* ignore errors, just check how much was successfully transferred */
5516 while (len) {
5517 int bytes, ret, offset;
5518 void *maddr;
5519 struct page *page = NULL;
5520
5521 ret = get_user_pages_remote(mm, addr, 1,
5522 gup_flags, &page, &vma, NULL);
5523 if (ret <= 0) {
5524#ifndef CONFIG_HAVE_IOREMAP_PROT
5525 break;
5526#else
5527 /*
5528 * Check if this is a VM_IO | VM_PFNMAP VMA, which
5529 * we can access using slightly different code.
5530 */
5531 vma = vma_lookup(mm, addr);
5532 if (!vma)
5533 break;
5534 if (vma->vm_ops && vma->vm_ops->access)
5535 ret = vma->vm_ops->access(vma, addr, buf,
5536 len, write);
5537 if (ret <= 0)
5538 break;
5539 bytes = ret;
5540#endif
5541 } else {
5542 bytes = len;
5543 offset = addr & (PAGE_SIZE-1);
5544 if (bytes > PAGE_SIZE-offset)
5545 bytes = PAGE_SIZE-offset;
5546
5547 maddr = kmap(page);
5548 if (write) {
5549 copy_to_user_page(vma, page, addr,
5550 maddr + offset, buf, bytes);
5551 set_page_dirty_lock(page);
5552 } else {
5553 copy_from_user_page(vma, page, addr,
5554 buf, maddr + offset, bytes);
5555 }
5556 kunmap(page);
5557 put_page(page);
5558 }
5559 len -= bytes;
5560 buf += bytes;
5561 addr += bytes;
5562 }
5563 mmap_read_unlock(mm);
5564
5565 return buf - old_buf;
5566}
5567
5568/**
5569 * access_remote_vm - access another process' address space
5570 * @mm: the mm_struct of the target address space
5571 * @addr: start address to access
5572 * @buf: source or destination buffer
5573 * @len: number of bytes to transfer
5574 * @gup_flags: flags modifying lookup behaviour
5575 *
5576 * The caller must hold a reference on @mm.
5577 *
5578 * Return: number of bytes copied from source to destination.
5579 */
5580int access_remote_vm(struct mm_struct *mm, unsigned long addr,
5581 void *buf, int len, unsigned int gup_flags)
5582{
5583 return __access_remote_vm(mm, addr, buf, len, gup_flags);
5584}
5585
5586/*
5587 * Access another process' address space.
5588 * Source/target buffer must be kernel space,
5589 * Do not walk the page table directly, use get_user_pages
5590 */
5591int access_process_vm(struct task_struct *tsk, unsigned long addr,
5592 void *buf, int len, unsigned int gup_flags)
5593{
5594 struct mm_struct *mm;
5595 int ret;
5596
5597 mm = get_task_mm(tsk);
5598 if (!mm)
5599 return 0;
5600
5601 ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
5602
5603 mmput(mm);
5604
5605 return ret;
5606}
5607EXPORT_SYMBOL_GPL(access_process_vm);
5608
5609/*
5610 * Print the name of a VMA.
5611 */
5612void print_vma_addr(char *prefix, unsigned long ip)
5613{
5614 struct mm_struct *mm = current->mm;
5615 struct vm_area_struct *vma;
5616
5617 /*
5618 * we might be running from an atomic context so we cannot sleep
5619 */
5620 if (!mmap_read_trylock(mm))
5621 return;
5622
5623 vma = find_vma(mm, ip);
5624 if (vma && vma->vm_file) {
5625 struct file *f = vma->vm_file;
5626 char *buf = (char *)__get_free_page(GFP_NOWAIT);
5627 if (buf) {
5628 char *p;
5629
5630 p = file_path(f, buf, PAGE_SIZE);
5631 if (IS_ERR(p))
5632 p = "?";
5633 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
5634 vma->vm_start,
5635 vma->vm_end - vma->vm_start);
5636 free_page((unsigned long)buf);
5637 }
5638 }
5639 mmap_read_unlock(mm);
5640}
5641
5642#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5643void __might_fault(const char *file, int line)
5644{
5645 if (pagefault_disabled())
5646 return;
5647 __might_sleep(file, line);
5648#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5649 if (current->mm)
5650 might_lock_read(¤t->mm->mmap_lock);
5651#endif
5652}
5653EXPORT_SYMBOL(__might_fault);
5654#endif
5655
5656#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
5657/*
5658 * Process all subpages of the specified huge page with the specified
5659 * operation. The target subpage will be processed last to keep its
5660 * cache lines hot.
5661 */
5662static inline void process_huge_page(
5663 unsigned long addr_hint, unsigned int pages_per_huge_page,
5664 void (*process_subpage)(unsigned long addr, int idx, void *arg),
5665 void *arg)
5666{
5667 int i, n, base, l;
5668 unsigned long addr = addr_hint &
5669 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5670
5671 /* Process target subpage last to keep its cache lines hot */
5672 might_sleep();
5673 n = (addr_hint - addr) / PAGE_SIZE;
5674 if (2 * n <= pages_per_huge_page) {
5675 /* If target subpage in first half of huge page */
5676 base = 0;
5677 l = n;
5678 /* Process subpages at the end of huge page */
5679 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
5680 cond_resched();
5681 process_subpage(addr + i * PAGE_SIZE, i, arg);
5682 }
5683 } else {
5684 /* If target subpage in second half of huge page */
5685 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
5686 l = pages_per_huge_page - n;
5687 /* Process subpages at the begin of huge page */
5688 for (i = 0; i < base; i++) {
5689 cond_resched();
5690 process_subpage(addr + i * PAGE_SIZE, i, arg);
5691 }
5692 }
5693 /*
5694 * Process remaining subpages in left-right-left-right pattern
5695 * towards the target subpage
5696 */
5697 for (i = 0; i < l; i++) {
5698 int left_idx = base + i;
5699 int right_idx = base + 2 * l - 1 - i;
5700
5701 cond_resched();
5702 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
5703 cond_resched();
5704 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
5705 }
5706}
5707
5708static void clear_gigantic_page(struct page *page,
5709 unsigned long addr,
5710 unsigned int pages_per_huge_page)
5711{
5712 int i;
5713 struct page *p;
5714
5715 might_sleep();
5716 for (i = 0; i < pages_per_huge_page; i++) {
5717 p = nth_page(page, i);
5718 cond_resched();
5719 clear_user_highpage(p, addr + i * PAGE_SIZE);
5720 }
5721}
5722
5723static void clear_subpage(unsigned long addr, int idx, void *arg)
5724{
5725 struct page *page = arg;
5726
5727 clear_user_highpage(page + idx, addr);
5728}
5729
5730void clear_huge_page(struct page *page,
5731 unsigned long addr_hint, unsigned int pages_per_huge_page)
5732{
5733 unsigned long addr = addr_hint &
5734 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5735
5736 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5737 clear_gigantic_page(page, addr, pages_per_huge_page);
5738 return;
5739 }
5740
5741 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
5742}
5743
5744static void copy_user_gigantic_page(struct page *dst, struct page *src,
5745 unsigned long addr,
5746 struct vm_area_struct *vma,
5747 unsigned int pages_per_huge_page)
5748{
5749 int i;
5750 struct page *dst_base = dst;
5751 struct page *src_base = src;
5752
5753 for (i = 0; i < pages_per_huge_page; i++) {
5754 dst = nth_page(dst_base, i);
5755 src = nth_page(src_base, i);
5756
5757 cond_resched();
5758 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
5759 }
5760}
5761
5762struct copy_subpage_arg {
5763 struct page *dst;
5764 struct page *src;
5765 struct vm_area_struct *vma;
5766};
5767
5768static void copy_subpage(unsigned long addr, int idx, void *arg)
5769{
5770 struct copy_subpage_arg *copy_arg = arg;
5771
5772 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
5773 addr, copy_arg->vma);
5774}
5775
5776void copy_user_huge_page(struct page *dst, struct page *src,
5777 unsigned long addr_hint, struct vm_area_struct *vma,
5778 unsigned int pages_per_huge_page)
5779{
5780 unsigned long addr = addr_hint &
5781 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5782 struct copy_subpage_arg arg = {
5783 .dst = dst,
5784 .src = src,
5785 .vma = vma,
5786 };
5787
5788 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5789 copy_user_gigantic_page(dst, src, addr, vma,
5790 pages_per_huge_page);
5791 return;
5792 }
5793
5794 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
5795}
5796
5797long copy_huge_page_from_user(struct page *dst_page,
5798 const void __user *usr_src,
5799 unsigned int pages_per_huge_page,
5800 bool allow_pagefault)
5801{
5802 void *page_kaddr;
5803 unsigned long i, rc = 0;
5804 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
5805 struct page *subpage;
5806
5807 for (i = 0; i < pages_per_huge_page; i++) {
5808 subpage = nth_page(dst_page, i);
5809 if (allow_pagefault)
5810 page_kaddr = kmap(subpage);
5811 else
5812 page_kaddr = kmap_atomic(subpage);
5813 rc = copy_from_user(page_kaddr,
5814 usr_src + i * PAGE_SIZE, PAGE_SIZE);
5815 if (allow_pagefault)
5816 kunmap(subpage);
5817 else
5818 kunmap_atomic(page_kaddr);
5819
5820 ret_val -= (PAGE_SIZE - rc);
5821 if (rc)
5822 break;
5823
5824 flush_dcache_page(subpage);
5825
5826 cond_resched();
5827 }
5828 return ret_val;
5829}
5830#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
5831
5832#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
5833
5834static struct kmem_cache *page_ptl_cachep;
5835
5836void __init ptlock_cache_init(void)
5837{
5838 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
5839 SLAB_PANIC, NULL);
5840}
5841
5842bool ptlock_alloc(struct page *page)
5843{
5844 spinlock_t *ptl;
5845
5846 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
5847 if (!ptl)
5848 return false;
5849 page->ptl = ptl;
5850 return true;
5851}
5852
5853void ptlock_free(struct page *page)
5854{
5855 kmem_cache_free(page_ptl_cachep, page->ptl);
5856}
5857#endif
1/*
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/module.h>
51#include <linux/delayacct.h>
52#include <linux/init.h>
53#include <linux/writeback.h>
54#include <linux/memcontrol.h>
55#include <linux/mmu_notifier.h>
56#include <linux/kallsyms.h>
57#include <linux/swapops.h>
58#include <linux/elf.h>
59#include <linux/gfp.h>
60
61#include <asm/io.h>
62#include <asm/pgalloc.h>
63#include <asm/uaccess.h>
64#include <asm/tlb.h>
65#include <asm/tlbflush.h>
66#include <asm/pgtable.h>
67
68#include "internal.h"
69
70#ifndef CONFIG_NEED_MULTIPLE_NODES
71/* use the per-pgdat data instead for discontigmem - mbligh */
72unsigned long max_mapnr;
73struct page *mem_map;
74
75EXPORT_SYMBOL(max_mapnr);
76EXPORT_SYMBOL(mem_map);
77#endif
78
79unsigned long num_physpages;
80/*
81 * A number of key systems in x86 including ioremap() rely on the assumption
82 * that high_memory defines the upper bound on direct map memory, then end
83 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85 * and ZONE_HIGHMEM.
86 */
87void * high_memory;
88
89EXPORT_SYMBOL(num_physpages);
90EXPORT_SYMBOL(high_memory);
91
92/*
93 * Randomize the address space (stacks, mmaps, brk, etc.).
94 *
95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96 * as ancient (libc5 based) binaries can segfault. )
97 */
98int randomize_va_space __read_mostly =
99#ifdef CONFIG_COMPAT_BRK
100 1;
101#else
102 2;
103#endif
104
105static int __init disable_randmaps(char *s)
106{
107 randomize_va_space = 0;
108 return 1;
109}
110__setup("norandmaps", disable_randmaps);
111
112unsigned long zero_pfn __read_mostly;
113unsigned long highest_memmap_pfn __read_mostly;
114
115/*
116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117 */
118static int __init init_zero_pfn(void)
119{
120 zero_pfn = page_to_pfn(ZERO_PAGE(0));
121 return 0;
122}
123core_initcall(init_zero_pfn);
124
125
126#if defined(SPLIT_RSS_COUNTING)
127
128static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
129{
130 int i;
131
132 for (i = 0; i < NR_MM_COUNTERS; i++) {
133 if (task->rss_stat.count[i]) {
134 add_mm_counter(mm, i, task->rss_stat.count[i]);
135 task->rss_stat.count[i] = 0;
136 }
137 }
138 task->rss_stat.events = 0;
139}
140
141static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142{
143 struct task_struct *task = current;
144
145 if (likely(task->mm == mm))
146 task->rss_stat.count[member] += val;
147 else
148 add_mm_counter(mm, member, val);
149}
150#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152
153/* sync counter once per 64 page faults */
154#define TASK_RSS_EVENTS_THRESH (64)
155static void check_sync_rss_stat(struct task_struct *task)
156{
157 if (unlikely(task != current))
158 return;
159 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160 __sync_task_rss_stat(task, task->mm);
161}
162
163unsigned long get_mm_counter(struct mm_struct *mm, int member)
164{
165 long val = 0;
166
167 /*
168 * Don't use task->mm here...for avoiding to use task_get_mm()..
169 * The caller must guarantee task->mm is not invalid.
170 */
171 val = atomic_long_read(&mm->rss_stat.count[member]);
172 /*
173 * counter is updated in asynchronous manner and may go to minus.
174 * But it's never be expected number for users.
175 */
176 if (val < 0)
177 return 0;
178 return (unsigned long)val;
179}
180
181void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
182{
183 __sync_task_rss_stat(task, mm);
184}
185#else /* SPLIT_RSS_COUNTING */
186
187#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
189
190static void check_sync_rss_stat(struct task_struct *task)
191{
192}
193
194#endif /* SPLIT_RSS_COUNTING */
195
196#ifdef HAVE_GENERIC_MMU_GATHER
197
198static int tlb_next_batch(struct mmu_gather *tlb)
199{
200 struct mmu_gather_batch *batch;
201
202 batch = tlb->active;
203 if (batch->next) {
204 tlb->active = batch->next;
205 return 1;
206 }
207
208 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
209 if (!batch)
210 return 0;
211
212 batch->next = NULL;
213 batch->nr = 0;
214 batch->max = MAX_GATHER_BATCH;
215
216 tlb->active->next = batch;
217 tlb->active = batch;
218
219 return 1;
220}
221
222/* tlb_gather_mmu
223 * Called to initialize an (on-stack) mmu_gather structure for page-table
224 * tear-down from @mm. The @fullmm argument is used when @mm is without
225 * users and we're going to destroy the full address space (exit/execve).
226 */
227void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
228{
229 tlb->mm = mm;
230
231 tlb->fullmm = fullmm;
232 tlb->need_flush = 0;
233 tlb->fast_mode = (num_possible_cpus() == 1);
234 tlb->local.next = NULL;
235 tlb->local.nr = 0;
236 tlb->local.max = ARRAY_SIZE(tlb->__pages);
237 tlb->active = &tlb->local;
238
239#ifdef CONFIG_HAVE_RCU_TABLE_FREE
240 tlb->batch = NULL;
241#endif
242}
243
244void tlb_flush_mmu(struct mmu_gather *tlb)
245{
246 struct mmu_gather_batch *batch;
247
248 if (!tlb->need_flush)
249 return;
250 tlb->need_flush = 0;
251 tlb_flush(tlb);
252#ifdef CONFIG_HAVE_RCU_TABLE_FREE
253 tlb_table_flush(tlb);
254#endif
255
256 if (tlb_fast_mode(tlb))
257 return;
258
259 for (batch = &tlb->local; batch; batch = batch->next) {
260 free_pages_and_swap_cache(batch->pages, batch->nr);
261 batch->nr = 0;
262 }
263 tlb->active = &tlb->local;
264}
265
266/* tlb_finish_mmu
267 * Called at the end of the shootdown operation to free up any resources
268 * that were required.
269 */
270void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
271{
272 struct mmu_gather_batch *batch, *next;
273
274 tlb_flush_mmu(tlb);
275
276 /* keep the page table cache within bounds */
277 check_pgt_cache();
278
279 for (batch = tlb->local.next; batch; batch = next) {
280 next = batch->next;
281 free_pages((unsigned long)batch, 0);
282 }
283 tlb->local.next = NULL;
284}
285
286/* __tlb_remove_page
287 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
288 * handling the additional races in SMP caused by other CPUs caching valid
289 * mappings in their TLBs. Returns the number of free page slots left.
290 * When out of page slots we must call tlb_flush_mmu().
291 */
292int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
293{
294 struct mmu_gather_batch *batch;
295
296 tlb->need_flush = 1;
297
298 if (tlb_fast_mode(tlb)) {
299 free_page_and_swap_cache(page);
300 return 1; /* avoid calling tlb_flush_mmu() */
301 }
302
303 batch = tlb->active;
304 batch->pages[batch->nr++] = page;
305 if (batch->nr == batch->max) {
306 if (!tlb_next_batch(tlb))
307 return 0;
308 batch = tlb->active;
309 }
310 VM_BUG_ON(batch->nr > batch->max);
311
312 return batch->max - batch->nr;
313}
314
315#endif /* HAVE_GENERIC_MMU_GATHER */
316
317#ifdef CONFIG_HAVE_RCU_TABLE_FREE
318
319/*
320 * See the comment near struct mmu_table_batch.
321 */
322
323static void tlb_remove_table_smp_sync(void *arg)
324{
325 /* Simply deliver the interrupt */
326}
327
328static void tlb_remove_table_one(void *table)
329{
330 /*
331 * This isn't an RCU grace period and hence the page-tables cannot be
332 * assumed to be actually RCU-freed.
333 *
334 * It is however sufficient for software page-table walkers that rely on
335 * IRQ disabling. See the comment near struct mmu_table_batch.
336 */
337 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
338 __tlb_remove_table(table);
339}
340
341static void tlb_remove_table_rcu(struct rcu_head *head)
342{
343 struct mmu_table_batch *batch;
344 int i;
345
346 batch = container_of(head, struct mmu_table_batch, rcu);
347
348 for (i = 0; i < batch->nr; i++)
349 __tlb_remove_table(batch->tables[i]);
350
351 free_page((unsigned long)batch);
352}
353
354void tlb_table_flush(struct mmu_gather *tlb)
355{
356 struct mmu_table_batch **batch = &tlb->batch;
357
358 if (*batch) {
359 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
360 *batch = NULL;
361 }
362}
363
364void tlb_remove_table(struct mmu_gather *tlb, void *table)
365{
366 struct mmu_table_batch **batch = &tlb->batch;
367
368 tlb->need_flush = 1;
369
370 /*
371 * When there's less then two users of this mm there cannot be a
372 * concurrent page-table walk.
373 */
374 if (atomic_read(&tlb->mm->mm_users) < 2) {
375 __tlb_remove_table(table);
376 return;
377 }
378
379 if (*batch == NULL) {
380 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
381 if (*batch == NULL) {
382 tlb_remove_table_one(table);
383 return;
384 }
385 (*batch)->nr = 0;
386 }
387 (*batch)->tables[(*batch)->nr++] = table;
388 if ((*batch)->nr == MAX_TABLE_BATCH)
389 tlb_table_flush(tlb);
390}
391
392#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
393
394/*
395 * If a p?d_bad entry is found while walking page tables, report
396 * the error, before resetting entry to p?d_none. Usually (but
397 * very seldom) called out from the p?d_none_or_clear_bad macros.
398 */
399
400void pgd_clear_bad(pgd_t *pgd)
401{
402 pgd_ERROR(*pgd);
403 pgd_clear(pgd);
404}
405
406void pud_clear_bad(pud_t *pud)
407{
408 pud_ERROR(*pud);
409 pud_clear(pud);
410}
411
412void pmd_clear_bad(pmd_t *pmd)
413{
414 pmd_ERROR(*pmd);
415 pmd_clear(pmd);
416}
417
418/*
419 * Note: this doesn't free the actual pages themselves. That
420 * has been handled earlier when unmapping all the memory regions.
421 */
422static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
423 unsigned long addr)
424{
425 pgtable_t token = pmd_pgtable(*pmd);
426 pmd_clear(pmd);
427 pte_free_tlb(tlb, token, addr);
428 tlb->mm->nr_ptes--;
429}
430
431static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
432 unsigned long addr, unsigned long end,
433 unsigned long floor, unsigned long ceiling)
434{
435 pmd_t *pmd;
436 unsigned long next;
437 unsigned long start;
438
439 start = addr;
440 pmd = pmd_offset(pud, addr);
441 do {
442 next = pmd_addr_end(addr, end);
443 if (pmd_none_or_clear_bad(pmd))
444 continue;
445 free_pte_range(tlb, pmd, addr);
446 } while (pmd++, addr = next, addr != end);
447
448 start &= PUD_MASK;
449 if (start < floor)
450 return;
451 if (ceiling) {
452 ceiling &= PUD_MASK;
453 if (!ceiling)
454 return;
455 }
456 if (end - 1 > ceiling - 1)
457 return;
458
459 pmd = pmd_offset(pud, start);
460 pud_clear(pud);
461 pmd_free_tlb(tlb, pmd, start);
462}
463
464static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
465 unsigned long addr, unsigned long end,
466 unsigned long floor, unsigned long ceiling)
467{
468 pud_t *pud;
469 unsigned long next;
470 unsigned long start;
471
472 start = addr;
473 pud = pud_offset(pgd, addr);
474 do {
475 next = pud_addr_end(addr, end);
476 if (pud_none_or_clear_bad(pud))
477 continue;
478 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
479 } while (pud++, addr = next, addr != end);
480
481 start &= PGDIR_MASK;
482 if (start < floor)
483 return;
484 if (ceiling) {
485 ceiling &= PGDIR_MASK;
486 if (!ceiling)
487 return;
488 }
489 if (end - 1 > ceiling - 1)
490 return;
491
492 pud = pud_offset(pgd, start);
493 pgd_clear(pgd);
494 pud_free_tlb(tlb, pud, start);
495}
496
497/*
498 * This function frees user-level page tables of a process.
499 *
500 * Must be called with pagetable lock held.
501 */
502void free_pgd_range(struct mmu_gather *tlb,
503 unsigned long addr, unsigned long end,
504 unsigned long floor, unsigned long ceiling)
505{
506 pgd_t *pgd;
507 unsigned long next;
508
509 /*
510 * The next few lines have given us lots of grief...
511 *
512 * Why are we testing PMD* at this top level? Because often
513 * there will be no work to do at all, and we'd prefer not to
514 * go all the way down to the bottom just to discover that.
515 *
516 * Why all these "- 1"s? Because 0 represents both the bottom
517 * of the address space and the top of it (using -1 for the
518 * top wouldn't help much: the masks would do the wrong thing).
519 * The rule is that addr 0 and floor 0 refer to the bottom of
520 * the address space, but end 0 and ceiling 0 refer to the top
521 * Comparisons need to use "end - 1" and "ceiling - 1" (though
522 * that end 0 case should be mythical).
523 *
524 * Wherever addr is brought up or ceiling brought down, we must
525 * be careful to reject "the opposite 0" before it confuses the
526 * subsequent tests. But what about where end is brought down
527 * by PMD_SIZE below? no, end can't go down to 0 there.
528 *
529 * Whereas we round start (addr) and ceiling down, by different
530 * masks at different levels, in order to test whether a table
531 * now has no other vmas using it, so can be freed, we don't
532 * bother to round floor or end up - the tests don't need that.
533 */
534
535 addr &= PMD_MASK;
536 if (addr < floor) {
537 addr += PMD_SIZE;
538 if (!addr)
539 return;
540 }
541 if (ceiling) {
542 ceiling &= PMD_MASK;
543 if (!ceiling)
544 return;
545 }
546 if (end - 1 > ceiling - 1)
547 end -= PMD_SIZE;
548 if (addr > end - 1)
549 return;
550
551 pgd = pgd_offset(tlb->mm, addr);
552 do {
553 next = pgd_addr_end(addr, end);
554 if (pgd_none_or_clear_bad(pgd))
555 continue;
556 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
557 } while (pgd++, addr = next, addr != end);
558}
559
560void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
561 unsigned long floor, unsigned long ceiling)
562{
563 while (vma) {
564 struct vm_area_struct *next = vma->vm_next;
565 unsigned long addr = vma->vm_start;
566
567 /*
568 * Hide vma from rmap and truncate_pagecache before freeing
569 * pgtables
570 */
571 unlink_anon_vmas(vma);
572 unlink_file_vma(vma);
573
574 if (is_vm_hugetlb_page(vma)) {
575 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
576 floor, next? next->vm_start: ceiling);
577 } else {
578 /*
579 * Optimization: gather nearby vmas into one call down
580 */
581 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
582 && !is_vm_hugetlb_page(next)) {
583 vma = next;
584 next = vma->vm_next;
585 unlink_anon_vmas(vma);
586 unlink_file_vma(vma);
587 }
588 free_pgd_range(tlb, addr, vma->vm_end,
589 floor, next? next->vm_start: ceiling);
590 }
591 vma = next;
592 }
593}
594
595int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
596 pmd_t *pmd, unsigned long address)
597{
598 pgtable_t new = pte_alloc_one(mm, address);
599 int wait_split_huge_page;
600 if (!new)
601 return -ENOMEM;
602
603 /*
604 * Ensure all pte setup (eg. pte page lock and page clearing) are
605 * visible before the pte is made visible to other CPUs by being
606 * put into page tables.
607 *
608 * The other side of the story is the pointer chasing in the page
609 * table walking code (when walking the page table without locking;
610 * ie. most of the time). Fortunately, these data accesses consist
611 * of a chain of data-dependent loads, meaning most CPUs (alpha
612 * being the notable exception) will already guarantee loads are
613 * seen in-order. See the alpha page table accessors for the
614 * smp_read_barrier_depends() barriers in page table walking code.
615 */
616 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
617
618 spin_lock(&mm->page_table_lock);
619 wait_split_huge_page = 0;
620 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
621 mm->nr_ptes++;
622 pmd_populate(mm, pmd, new);
623 new = NULL;
624 } else if (unlikely(pmd_trans_splitting(*pmd)))
625 wait_split_huge_page = 1;
626 spin_unlock(&mm->page_table_lock);
627 if (new)
628 pte_free(mm, new);
629 if (wait_split_huge_page)
630 wait_split_huge_page(vma->anon_vma, pmd);
631 return 0;
632}
633
634int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
635{
636 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
637 if (!new)
638 return -ENOMEM;
639
640 smp_wmb(); /* See comment in __pte_alloc */
641
642 spin_lock(&init_mm.page_table_lock);
643 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
644 pmd_populate_kernel(&init_mm, pmd, new);
645 new = NULL;
646 } else
647 VM_BUG_ON(pmd_trans_splitting(*pmd));
648 spin_unlock(&init_mm.page_table_lock);
649 if (new)
650 pte_free_kernel(&init_mm, new);
651 return 0;
652}
653
654static inline void init_rss_vec(int *rss)
655{
656 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
657}
658
659static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
660{
661 int i;
662
663 if (current->mm == mm)
664 sync_mm_rss(current, mm);
665 for (i = 0; i < NR_MM_COUNTERS; i++)
666 if (rss[i])
667 add_mm_counter(mm, i, rss[i]);
668}
669
670/*
671 * This function is called to print an error when a bad pte
672 * is found. For example, we might have a PFN-mapped pte in
673 * a region that doesn't allow it.
674 *
675 * The calling function must still handle the error.
676 */
677static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
678 pte_t pte, struct page *page)
679{
680 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
681 pud_t *pud = pud_offset(pgd, addr);
682 pmd_t *pmd = pmd_offset(pud, addr);
683 struct address_space *mapping;
684 pgoff_t index;
685 static unsigned long resume;
686 static unsigned long nr_shown;
687 static unsigned long nr_unshown;
688
689 /*
690 * Allow a burst of 60 reports, then keep quiet for that minute;
691 * or allow a steady drip of one report per second.
692 */
693 if (nr_shown == 60) {
694 if (time_before(jiffies, resume)) {
695 nr_unshown++;
696 return;
697 }
698 if (nr_unshown) {
699 printk(KERN_ALERT
700 "BUG: Bad page map: %lu messages suppressed\n",
701 nr_unshown);
702 nr_unshown = 0;
703 }
704 nr_shown = 0;
705 }
706 if (nr_shown++ == 0)
707 resume = jiffies + 60 * HZ;
708
709 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
710 index = linear_page_index(vma, addr);
711
712 printk(KERN_ALERT
713 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
714 current->comm,
715 (long long)pte_val(pte), (long long)pmd_val(*pmd));
716 if (page)
717 dump_page(page);
718 printk(KERN_ALERT
719 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
720 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
721 /*
722 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
723 */
724 if (vma->vm_ops)
725 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
726 (unsigned long)vma->vm_ops->fault);
727 if (vma->vm_file && vma->vm_file->f_op)
728 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
729 (unsigned long)vma->vm_file->f_op->mmap);
730 dump_stack();
731 add_taint(TAINT_BAD_PAGE);
732}
733
734static inline int is_cow_mapping(vm_flags_t flags)
735{
736 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
737}
738
739#ifndef is_zero_pfn
740static inline int is_zero_pfn(unsigned long pfn)
741{
742 return pfn == zero_pfn;
743}
744#endif
745
746#ifndef my_zero_pfn
747static inline unsigned long my_zero_pfn(unsigned long addr)
748{
749 return zero_pfn;
750}
751#endif
752
753/*
754 * vm_normal_page -- This function gets the "struct page" associated with a pte.
755 *
756 * "Special" mappings do not wish to be associated with a "struct page" (either
757 * it doesn't exist, or it exists but they don't want to touch it). In this
758 * case, NULL is returned here. "Normal" mappings do have a struct page.
759 *
760 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
761 * pte bit, in which case this function is trivial. Secondly, an architecture
762 * may not have a spare pte bit, which requires a more complicated scheme,
763 * described below.
764 *
765 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
766 * special mapping (even if there are underlying and valid "struct pages").
767 * COWed pages of a VM_PFNMAP are always normal.
768 *
769 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
770 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
771 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
772 * mapping will always honor the rule
773 *
774 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
775 *
776 * And for normal mappings this is false.
777 *
778 * This restricts such mappings to be a linear translation from virtual address
779 * to pfn. To get around this restriction, we allow arbitrary mappings so long
780 * as the vma is not a COW mapping; in that case, we know that all ptes are
781 * special (because none can have been COWed).
782 *
783 *
784 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
785 *
786 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
787 * page" backing, however the difference is that _all_ pages with a struct
788 * page (that is, those where pfn_valid is true) are refcounted and considered
789 * normal pages by the VM. The disadvantage is that pages are refcounted
790 * (which can be slower and simply not an option for some PFNMAP users). The
791 * advantage is that we don't have to follow the strict linearity rule of
792 * PFNMAP mappings in order to support COWable mappings.
793 *
794 */
795#ifdef __HAVE_ARCH_PTE_SPECIAL
796# define HAVE_PTE_SPECIAL 1
797#else
798# define HAVE_PTE_SPECIAL 0
799#endif
800struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
801 pte_t pte)
802{
803 unsigned long pfn = pte_pfn(pte);
804
805 if (HAVE_PTE_SPECIAL) {
806 if (likely(!pte_special(pte)))
807 goto check_pfn;
808 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
809 return NULL;
810 if (!is_zero_pfn(pfn))
811 print_bad_pte(vma, addr, pte, NULL);
812 return NULL;
813 }
814
815 /* !HAVE_PTE_SPECIAL case follows: */
816
817 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
818 if (vma->vm_flags & VM_MIXEDMAP) {
819 if (!pfn_valid(pfn))
820 return NULL;
821 goto out;
822 } else {
823 unsigned long off;
824 off = (addr - vma->vm_start) >> PAGE_SHIFT;
825 if (pfn == vma->vm_pgoff + off)
826 return NULL;
827 if (!is_cow_mapping(vma->vm_flags))
828 return NULL;
829 }
830 }
831
832 if (is_zero_pfn(pfn))
833 return NULL;
834check_pfn:
835 if (unlikely(pfn > highest_memmap_pfn)) {
836 print_bad_pte(vma, addr, pte, NULL);
837 return NULL;
838 }
839
840 /*
841 * NOTE! We still have PageReserved() pages in the page tables.
842 * eg. VDSO mappings can cause them to exist.
843 */
844out:
845 return pfn_to_page(pfn);
846}
847
848/*
849 * copy one vm_area from one task to the other. Assumes the page tables
850 * already present in the new task to be cleared in the whole range
851 * covered by this vma.
852 */
853
854static inline unsigned long
855copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
856 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
857 unsigned long addr, int *rss)
858{
859 unsigned long vm_flags = vma->vm_flags;
860 pte_t pte = *src_pte;
861 struct page *page;
862
863 /* pte contains position in swap or file, so copy. */
864 if (unlikely(!pte_present(pte))) {
865 if (!pte_file(pte)) {
866 swp_entry_t entry = pte_to_swp_entry(pte);
867
868 if (swap_duplicate(entry) < 0)
869 return entry.val;
870
871 /* make sure dst_mm is on swapoff's mmlist. */
872 if (unlikely(list_empty(&dst_mm->mmlist))) {
873 spin_lock(&mmlist_lock);
874 if (list_empty(&dst_mm->mmlist))
875 list_add(&dst_mm->mmlist,
876 &src_mm->mmlist);
877 spin_unlock(&mmlist_lock);
878 }
879 if (likely(!non_swap_entry(entry)))
880 rss[MM_SWAPENTS]++;
881 else if (is_write_migration_entry(entry) &&
882 is_cow_mapping(vm_flags)) {
883 /*
884 * COW mappings require pages in both parent
885 * and child to be set to read.
886 */
887 make_migration_entry_read(&entry);
888 pte = swp_entry_to_pte(entry);
889 set_pte_at(src_mm, addr, src_pte, pte);
890 }
891 }
892 goto out_set_pte;
893 }
894
895 /*
896 * If it's a COW mapping, write protect it both
897 * in the parent and the child
898 */
899 if (is_cow_mapping(vm_flags)) {
900 ptep_set_wrprotect(src_mm, addr, src_pte);
901 pte = pte_wrprotect(pte);
902 }
903
904 /*
905 * If it's a shared mapping, mark it clean in
906 * the child
907 */
908 if (vm_flags & VM_SHARED)
909 pte = pte_mkclean(pte);
910 pte = pte_mkold(pte);
911
912 page = vm_normal_page(vma, addr, pte);
913 if (page) {
914 get_page(page);
915 page_dup_rmap(page);
916 if (PageAnon(page))
917 rss[MM_ANONPAGES]++;
918 else
919 rss[MM_FILEPAGES]++;
920 }
921
922out_set_pte:
923 set_pte_at(dst_mm, addr, dst_pte, pte);
924 return 0;
925}
926
927int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
928 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
929 unsigned long addr, unsigned long end)
930{
931 pte_t *orig_src_pte, *orig_dst_pte;
932 pte_t *src_pte, *dst_pte;
933 spinlock_t *src_ptl, *dst_ptl;
934 int progress = 0;
935 int rss[NR_MM_COUNTERS];
936 swp_entry_t entry = (swp_entry_t){0};
937
938again:
939 init_rss_vec(rss);
940
941 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
942 if (!dst_pte)
943 return -ENOMEM;
944 src_pte = pte_offset_map(src_pmd, addr);
945 src_ptl = pte_lockptr(src_mm, src_pmd);
946 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
947 orig_src_pte = src_pte;
948 orig_dst_pte = dst_pte;
949 arch_enter_lazy_mmu_mode();
950
951 do {
952 /*
953 * We are holding two locks at this point - either of them
954 * could generate latencies in another task on another CPU.
955 */
956 if (progress >= 32) {
957 progress = 0;
958 if (need_resched() ||
959 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
960 break;
961 }
962 if (pte_none(*src_pte)) {
963 progress++;
964 continue;
965 }
966 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
967 vma, addr, rss);
968 if (entry.val)
969 break;
970 progress += 8;
971 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
972
973 arch_leave_lazy_mmu_mode();
974 spin_unlock(src_ptl);
975 pte_unmap(orig_src_pte);
976 add_mm_rss_vec(dst_mm, rss);
977 pte_unmap_unlock(orig_dst_pte, dst_ptl);
978 cond_resched();
979
980 if (entry.val) {
981 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
982 return -ENOMEM;
983 progress = 0;
984 }
985 if (addr != end)
986 goto again;
987 return 0;
988}
989
990static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
991 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
992 unsigned long addr, unsigned long end)
993{
994 pmd_t *src_pmd, *dst_pmd;
995 unsigned long next;
996
997 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
998 if (!dst_pmd)
999 return -ENOMEM;
1000 src_pmd = pmd_offset(src_pud, addr);
1001 do {
1002 next = pmd_addr_end(addr, end);
1003 if (pmd_trans_huge(*src_pmd)) {
1004 int err;
1005 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1006 err = copy_huge_pmd(dst_mm, src_mm,
1007 dst_pmd, src_pmd, addr, vma);
1008 if (err == -ENOMEM)
1009 return -ENOMEM;
1010 if (!err)
1011 continue;
1012 /* fall through */
1013 }
1014 if (pmd_none_or_clear_bad(src_pmd))
1015 continue;
1016 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1017 vma, addr, next))
1018 return -ENOMEM;
1019 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1020 return 0;
1021}
1022
1023static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1024 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1025 unsigned long addr, unsigned long end)
1026{
1027 pud_t *src_pud, *dst_pud;
1028 unsigned long next;
1029
1030 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1031 if (!dst_pud)
1032 return -ENOMEM;
1033 src_pud = pud_offset(src_pgd, addr);
1034 do {
1035 next = pud_addr_end(addr, end);
1036 if (pud_none_or_clear_bad(src_pud))
1037 continue;
1038 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1039 vma, addr, next))
1040 return -ENOMEM;
1041 } while (dst_pud++, src_pud++, addr = next, addr != end);
1042 return 0;
1043}
1044
1045int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046 struct vm_area_struct *vma)
1047{
1048 pgd_t *src_pgd, *dst_pgd;
1049 unsigned long next;
1050 unsigned long addr = vma->vm_start;
1051 unsigned long end = vma->vm_end;
1052 int ret;
1053
1054 /*
1055 * Don't copy ptes where a page fault will fill them correctly.
1056 * Fork becomes much lighter when there are big shared or private
1057 * readonly mappings. The tradeoff is that copy_page_range is more
1058 * efficient than faulting.
1059 */
1060 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1061 if (!vma->anon_vma)
1062 return 0;
1063 }
1064
1065 if (is_vm_hugetlb_page(vma))
1066 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1067
1068 if (unlikely(is_pfn_mapping(vma))) {
1069 /*
1070 * We do not free on error cases below as remove_vma
1071 * gets called on error from higher level routine
1072 */
1073 ret = track_pfn_vma_copy(vma);
1074 if (ret)
1075 return ret;
1076 }
1077
1078 /*
1079 * We need to invalidate the secondary MMU mappings only when
1080 * there could be a permission downgrade on the ptes of the
1081 * parent mm. And a permission downgrade will only happen if
1082 * is_cow_mapping() returns true.
1083 */
1084 if (is_cow_mapping(vma->vm_flags))
1085 mmu_notifier_invalidate_range_start(src_mm, addr, end);
1086
1087 ret = 0;
1088 dst_pgd = pgd_offset(dst_mm, addr);
1089 src_pgd = pgd_offset(src_mm, addr);
1090 do {
1091 next = pgd_addr_end(addr, end);
1092 if (pgd_none_or_clear_bad(src_pgd))
1093 continue;
1094 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1095 vma, addr, next))) {
1096 ret = -ENOMEM;
1097 break;
1098 }
1099 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1100
1101 if (is_cow_mapping(vma->vm_flags))
1102 mmu_notifier_invalidate_range_end(src_mm,
1103 vma->vm_start, end);
1104 return ret;
1105}
1106
1107static unsigned long zap_pte_range(struct mmu_gather *tlb,
1108 struct vm_area_struct *vma, pmd_t *pmd,
1109 unsigned long addr, unsigned long end,
1110 struct zap_details *details)
1111{
1112 struct mm_struct *mm = tlb->mm;
1113 int force_flush = 0;
1114 int rss[NR_MM_COUNTERS];
1115 spinlock_t *ptl;
1116 pte_t *start_pte;
1117 pte_t *pte;
1118
1119again:
1120 init_rss_vec(rss);
1121 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1122 pte = start_pte;
1123 arch_enter_lazy_mmu_mode();
1124 do {
1125 pte_t ptent = *pte;
1126 if (pte_none(ptent)) {
1127 continue;
1128 }
1129
1130 if (pte_present(ptent)) {
1131 struct page *page;
1132
1133 page = vm_normal_page(vma, addr, ptent);
1134 if (unlikely(details) && page) {
1135 /*
1136 * unmap_shared_mapping_pages() wants to
1137 * invalidate cache without truncating:
1138 * unmap shared but keep private pages.
1139 */
1140 if (details->check_mapping &&
1141 details->check_mapping != page->mapping)
1142 continue;
1143 /*
1144 * Each page->index must be checked when
1145 * invalidating or truncating nonlinear.
1146 */
1147 if (details->nonlinear_vma &&
1148 (page->index < details->first_index ||
1149 page->index > details->last_index))
1150 continue;
1151 }
1152 ptent = ptep_get_and_clear_full(mm, addr, pte,
1153 tlb->fullmm);
1154 tlb_remove_tlb_entry(tlb, pte, addr);
1155 if (unlikely(!page))
1156 continue;
1157 if (unlikely(details) && details->nonlinear_vma
1158 && linear_page_index(details->nonlinear_vma,
1159 addr) != page->index)
1160 set_pte_at(mm, addr, pte,
1161 pgoff_to_pte(page->index));
1162 if (PageAnon(page))
1163 rss[MM_ANONPAGES]--;
1164 else {
1165 if (pte_dirty(ptent))
1166 set_page_dirty(page);
1167 if (pte_young(ptent) &&
1168 likely(!VM_SequentialReadHint(vma)))
1169 mark_page_accessed(page);
1170 rss[MM_FILEPAGES]--;
1171 }
1172 page_remove_rmap(page);
1173 if (unlikely(page_mapcount(page) < 0))
1174 print_bad_pte(vma, addr, ptent, page);
1175 force_flush = !__tlb_remove_page(tlb, page);
1176 if (force_flush)
1177 break;
1178 continue;
1179 }
1180 /*
1181 * If details->check_mapping, we leave swap entries;
1182 * if details->nonlinear_vma, we leave file entries.
1183 */
1184 if (unlikely(details))
1185 continue;
1186 if (pte_file(ptent)) {
1187 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1188 print_bad_pte(vma, addr, ptent, NULL);
1189 } else {
1190 swp_entry_t entry = pte_to_swp_entry(ptent);
1191
1192 if (!non_swap_entry(entry))
1193 rss[MM_SWAPENTS]--;
1194 if (unlikely(!free_swap_and_cache(entry)))
1195 print_bad_pte(vma, addr, ptent, NULL);
1196 }
1197 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198 } while (pte++, addr += PAGE_SIZE, addr != end);
1199
1200 add_mm_rss_vec(mm, rss);
1201 arch_leave_lazy_mmu_mode();
1202 pte_unmap_unlock(start_pte, ptl);
1203
1204 /*
1205 * mmu_gather ran out of room to batch pages, we break out of
1206 * the PTE lock to avoid doing the potential expensive TLB invalidate
1207 * and page-free while holding it.
1208 */
1209 if (force_flush) {
1210 force_flush = 0;
1211 tlb_flush_mmu(tlb);
1212 if (addr != end)
1213 goto again;
1214 }
1215
1216 return addr;
1217}
1218
1219static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1220 struct vm_area_struct *vma, pud_t *pud,
1221 unsigned long addr, unsigned long end,
1222 struct zap_details *details)
1223{
1224 pmd_t *pmd;
1225 unsigned long next;
1226
1227 pmd = pmd_offset(pud, addr);
1228 do {
1229 next = pmd_addr_end(addr, end);
1230 if (pmd_trans_huge(*pmd)) {
1231 if (next-addr != HPAGE_PMD_SIZE) {
1232 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1233 split_huge_page_pmd(vma->vm_mm, pmd);
1234 } else if (zap_huge_pmd(tlb, vma, pmd))
1235 continue;
1236 /* fall through */
1237 }
1238 if (pmd_none_or_clear_bad(pmd))
1239 continue;
1240 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1241 cond_resched();
1242 } while (pmd++, addr = next, addr != end);
1243
1244 return addr;
1245}
1246
1247static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1248 struct vm_area_struct *vma, pgd_t *pgd,
1249 unsigned long addr, unsigned long end,
1250 struct zap_details *details)
1251{
1252 pud_t *pud;
1253 unsigned long next;
1254
1255 pud = pud_offset(pgd, addr);
1256 do {
1257 next = pud_addr_end(addr, end);
1258 if (pud_none_or_clear_bad(pud))
1259 continue;
1260 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1261 } while (pud++, addr = next, addr != end);
1262
1263 return addr;
1264}
1265
1266static unsigned long unmap_page_range(struct mmu_gather *tlb,
1267 struct vm_area_struct *vma,
1268 unsigned long addr, unsigned long end,
1269 struct zap_details *details)
1270{
1271 pgd_t *pgd;
1272 unsigned long next;
1273
1274 if (details && !details->check_mapping && !details->nonlinear_vma)
1275 details = NULL;
1276
1277 BUG_ON(addr >= end);
1278 mem_cgroup_uncharge_start();
1279 tlb_start_vma(tlb, vma);
1280 pgd = pgd_offset(vma->vm_mm, addr);
1281 do {
1282 next = pgd_addr_end(addr, end);
1283 if (pgd_none_or_clear_bad(pgd))
1284 continue;
1285 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1286 } while (pgd++, addr = next, addr != end);
1287 tlb_end_vma(tlb, vma);
1288 mem_cgroup_uncharge_end();
1289
1290 return addr;
1291}
1292
1293/**
1294 * unmap_vmas - unmap a range of memory covered by a list of vma's
1295 * @tlb: address of the caller's struct mmu_gather
1296 * @vma: the starting vma
1297 * @start_addr: virtual address at which to start unmapping
1298 * @end_addr: virtual address at which to end unmapping
1299 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1300 * @details: details of nonlinear truncation or shared cache invalidation
1301 *
1302 * Returns the end address of the unmapping (restart addr if interrupted).
1303 *
1304 * Unmap all pages in the vma list.
1305 *
1306 * Only addresses between `start' and `end' will be unmapped.
1307 *
1308 * The VMA list must be sorted in ascending virtual address order.
1309 *
1310 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1311 * range after unmap_vmas() returns. So the only responsibility here is to
1312 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1313 * drops the lock and schedules.
1314 */
1315unsigned long unmap_vmas(struct mmu_gather *tlb,
1316 struct vm_area_struct *vma, unsigned long start_addr,
1317 unsigned long end_addr, unsigned long *nr_accounted,
1318 struct zap_details *details)
1319{
1320 unsigned long start = start_addr;
1321 struct mm_struct *mm = vma->vm_mm;
1322
1323 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1324 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1325 unsigned long end;
1326
1327 start = max(vma->vm_start, start_addr);
1328 if (start >= vma->vm_end)
1329 continue;
1330 end = min(vma->vm_end, end_addr);
1331 if (end <= vma->vm_start)
1332 continue;
1333
1334 if (vma->vm_flags & VM_ACCOUNT)
1335 *nr_accounted += (end - start) >> PAGE_SHIFT;
1336
1337 if (unlikely(is_pfn_mapping(vma)))
1338 untrack_pfn_vma(vma, 0, 0);
1339
1340 while (start != end) {
1341 if (unlikely(is_vm_hugetlb_page(vma))) {
1342 /*
1343 * It is undesirable to test vma->vm_file as it
1344 * should be non-null for valid hugetlb area.
1345 * However, vm_file will be NULL in the error
1346 * cleanup path of do_mmap_pgoff. When
1347 * hugetlbfs ->mmap method fails,
1348 * do_mmap_pgoff() nullifies vma->vm_file
1349 * before calling this function to clean up.
1350 * Since no pte has actually been setup, it is
1351 * safe to do nothing in this case.
1352 */
1353 if (vma->vm_file)
1354 unmap_hugepage_range(vma, start, end, NULL);
1355
1356 start = end;
1357 } else
1358 start = unmap_page_range(tlb, vma, start, end, details);
1359 }
1360 }
1361
1362 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1363 return start; /* which is now the end (or restart) address */
1364}
1365
1366/**
1367 * zap_page_range - remove user pages in a given range
1368 * @vma: vm_area_struct holding the applicable pages
1369 * @address: starting address of pages to zap
1370 * @size: number of bytes to zap
1371 * @details: details of nonlinear truncation or shared cache invalidation
1372 */
1373unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1374 unsigned long size, struct zap_details *details)
1375{
1376 struct mm_struct *mm = vma->vm_mm;
1377 struct mmu_gather tlb;
1378 unsigned long end = address + size;
1379 unsigned long nr_accounted = 0;
1380
1381 lru_add_drain();
1382 tlb_gather_mmu(&tlb, mm, 0);
1383 update_hiwater_rss(mm);
1384 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1385 tlb_finish_mmu(&tlb, address, end);
1386 return end;
1387}
1388
1389/**
1390 * zap_vma_ptes - remove ptes mapping the vma
1391 * @vma: vm_area_struct holding ptes to be zapped
1392 * @address: starting address of pages to zap
1393 * @size: number of bytes to zap
1394 *
1395 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1396 *
1397 * The entire address range must be fully contained within the vma.
1398 *
1399 * Returns 0 if successful.
1400 */
1401int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1402 unsigned long size)
1403{
1404 if (address < vma->vm_start || address + size > vma->vm_end ||
1405 !(vma->vm_flags & VM_PFNMAP))
1406 return -1;
1407 zap_page_range(vma, address, size, NULL);
1408 return 0;
1409}
1410EXPORT_SYMBOL_GPL(zap_vma_ptes);
1411
1412/**
1413 * follow_page - look up a page descriptor from a user-virtual address
1414 * @vma: vm_area_struct mapping @address
1415 * @address: virtual address to look up
1416 * @flags: flags modifying lookup behaviour
1417 *
1418 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1419 *
1420 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1421 * an error pointer if there is a mapping to something not represented
1422 * by a page descriptor (see also vm_normal_page()).
1423 */
1424struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1425 unsigned int flags)
1426{
1427 pgd_t *pgd;
1428 pud_t *pud;
1429 pmd_t *pmd;
1430 pte_t *ptep, pte;
1431 spinlock_t *ptl;
1432 struct page *page;
1433 struct mm_struct *mm = vma->vm_mm;
1434
1435 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1436 if (!IS_ERR(page)) {
1437 BUG_ON(flags & FOLL_GET);
1438 goto out;
1439 }
1440
1441 page = NULL;
1442 pgd = pgd_offset(mm, address);
1443 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1444 goto no_page_table;
1445
1446 pud = pud_offset(pgd, address);
1447 if (pud_none(*pud))
1448 goto no_page_table;
1449 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1450 BUG_ON(flags & FOLL_GET);
1451 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1452 goto out;
1453 }
1454 if (unlikely(pud_bad(*pud)))
1455 goto no_page_table;
1456
1457 pmd = pmd_offset(pud, address);
1458 if (pmd_none(*pmd))
1459 goto no_page_table;
1460 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1461 BUG_ON(flags & FOLL_GET);
1462 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1463 goto out;
1464 }
1465 if (pmd_trans_huge(*pmd)) {
1466 if (flags & FOLL_SPLIT) {
1467 split_huge_page_pmd(mm, pmd);
1468 goto split_fallthrough;
1469 }
1470 spin_lock(&mm->page_table_lock);
1471 if (likely(pmd_trans_huge(*pmd))) {
1472 if (unlikely(pmd_trans_splitting(*pmd))) {
1473 spin_unlock(&mm->page_table_lock);
1474 wait_split_huge_page(vma->anon_vma, pmd);
1475 } else {
1476 page = follow_trans_huge_pmd(mm, address,
1477 pmd, flags);
1478 spin_unlock(&mm->page_table_lock);
1479 goto out;
1480 }
1481 } else
1482 spin_unlock(&mm->page_table_lock);
1483 /* fall through */
1484 }
1485split_fallthrough:
1486 if (unlikely(pmd_bad(*pmd)))
1487 goto no_page_table;
1488
1489 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1490
1491 pte = *ptep;
1492 if (!pte_present(pte))
1493 goto no_page;
1494 if ((flags & FOLL_WRITE) && !pte_write(pte))
1495 goto unlock;
1496
1497 page = vm_normal_page(vma, address, pte);
1498 if (unlikely(!page)) {
1499 if ((flags & FOLL_DUMP) ||
1500 !is_zero_pfn(pte_pfn(pte)))
1501 goto bad_page;
1502 page = pte_page(pte);
1503 }
1504
1505 if (flags & FOLL_GET)
1506 get_page(page);
1507 if (flags & FOLL_TOUCH) {
1508 if ((flags & FOLL_WRITE) &&
1509 !pte_dirty(pte) && !PageDirty(page))
1510 set_page_dirty(page);
1511 /*
1512 * pte_mkyoung() would be more correct here, but atomic care
1513 * is needed to avoid losing the dirty bit: it is easier to use
1514 * mark_page_accessed().
1515 */
1516 mark_page_accessed(page);
1517 }
1518 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1519 /*
1520 * The preliminary mapping check is mainly to avoid the
1521 * pointless overhead of lock_page on the ZERO_PAGE
1522 * which might bounce very badly if there is contention.
1523 *
1524 * If the page is already locked, we don't need to
1525 * handle it now - vmscan will handle it later if and
1526 * when it attempts to reclaim the page.
1527 */
1528 if (page->mapping && trylock_page(page)) {
1529 lru_add_drain(); /* push cached pages to LRU */
1530 /*
1531 * Because we lock page here and migration is
1532 * blocked by the pte's page reference, we need
1533 * only check for file-cache page truncation.
1534 */
1535 if (page->mapping)
1536 mlock_vma_page(page);
1537 unlock_page(page);
1538 }
1539 }
1540unlock:
1541 pte_unmap_unlock(ptep, ptl);
1542out:
1543 return page;
1544
1545bad_page:
1546 pte_unmap_unlock(ptep, ptl);
1547 return ERR_PTR(-EFAULT);
1548
1549no_page:
1550 pte_unmap_unlock(ptep, ptl);
1551 if (!pte_none(pte))
1552 return page;
1553
1554no_page_table:
1555 /*
1556 * When core dumping an enormous anonymous area that nobody
1557 * has touched so far, we don't want to allocate unnecessary pages or
1558 * page tables. Return error instead of NULL to skip handle_mm_fault,
1559 * then get_dump_page() will return NULL to leave a hole in the dump.
1560 * But we can only make this optimization where a hole would surely
1561 * be zero-filled if handle_mm_fault() actually did handle it.
1562 */
1563 if ((flags & FOLL_DUMP) &&
1564 (!vma->vm_ops || !vma->vm_ops->fault))
1565 return ERR_PTR(-EFAULT);
1566 return page;
1567}
1568
1569static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1570{
1571 return stack_guard_page_start(vma, addr) ||
1572 stack_guard_page_end(vma, addr+PAGE_SIZE);
1573}
1574
1575/**
1576 * __get_user_pages() - pin user pages in memory
1577 * @tsk: task_struct of target task
1578 * @mm: mm_struct of target mm
1579 * @start: starting user address
1580 * @nr_pages: number of pages from start to pin
1581 * @gup_flags: flags modifying pin behaviour
1582 * @pages: array that receives pointers to the pages pinned.
1583 * Should be at least nr_pages long. Or NULL, if caller
1584 * only intends to ensure the pages are faulted in.
1585 * @vmas: array of pointers to vmas corresponding to each page.
1586 * Or NULL if the caller does not require them.
1587 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1588 *
1589 * Returns number of pages pinned. This may be fewer than the number
1590 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1591 * were pinned, returns -errno. Each page returned must be released
1592 * with a put_page() call when it is finished with. vmas will only
1593 * remain valid while mmap_sem is held.
1594 *
1595 * Must be called with mmap_sem held for read or write.
1596 *
1597 * __get_user_pages walks a process's page tables and takes a reference to
1598 * each struct page that each user address corresponds to at a given
1599 * instant. That is, it takes the page that would be accessed if a user
1600 * thread accesses the given user virtual address at that instant.
1601 *
1602 * This does not guarantee that the page exists in the user mappings when
1603 * __get_user_pages returns, and there may even be a completely different
1604 * page there in some cases (eg. if mmapped pagecache has been invalidated
1605 * and subsequently re faulted). However it does guarantee that the page
1606 * won't be freed completely. And mostly callers simply care that the page
1607 * contains data that was valid *at some point in time*. Typically, an IO
1608 * or similar operation cannot guarantee anything stronger anyway because
1609 * locks can't be held over the syscall boundary.
1610 *
1611 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1612 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1613 * appropriate) must be called after the page is finished with, and
1614 * before put_page is called.
1615 *
1616 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1617 * or mmap_sem contention, and if waiting is needed to pin all pages,
1618 * *@nonblocking will be set to 0.
1619 *
1620 * In most cases, get_user_pages or get_user_pages_fast should be used
1621 * instead of __get_user_pages. __get_user_pages should be used only if
1622 * you need some special @gup_flags.
1623 */
1624int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1625 unsigned long start, int nr_pages, unsigned int gup_flags,
1626 struct page **pages, struct vm_area_struct **vmas,
1627 int *nonblocking)
1628{
1629 int i;
1630 unsigned long vm_flags;
1631
1632 if (nr_pages <= 0)
1633 return 0;
1634
1635 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1636
1637 /*
1638 * Require read or write permissions.
1639 * If FOLL_FORCE is set, we only require the "MAY" flags.
1640 */
1641 vm_flags = (gup_flags & FOLL_WRITE) ?
1642 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1643 vm_flags &= (gup_flags & FOLL_FORCE) ?
1644 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1645 i = 0;
1646
1647 do {
1648 struct vm_area_struct *vma;
1649
1650 vma = find_extend_vma(mm, start);
1651 if (!vma && in_gate_area(mm, start)) {
1652 unsigned long pg = start & PAGE_MASK;
1653 pgd_t *pgd;
1654 pud_t *pud;
1655 pmd_t *pmd;
1656 pte_t *pte;
1657
1658 /* user gate pages are read-only */
1659 if (gup_flags & FOLL_WRITE)
1660 return i ? : -EFAULT;
1661 if (pg > TASK_SIZE)
1662 pgd = pgd_offset_k(pg);
1663 else
1664 pgd = pgd_offset_gate(mm, pg);
1665 BUG_ON(pgd_none(*pgd));
1666 pud = pud_offset(pgd, pg);
1667 BUG_ON(pud_none(*pud));
1668 pmd = pmd_offset(pud, pg);
1669 if (pmd_none(*pmd))
1670 return i ? : -EFAULT;
1671 VM_BUG_ON(pmd_trans_huge(*pmd));
1672 pte = pte_offset_map(pmd, pg);
1673 if (pte_none(*pte)) {
1674 pte_unmap(pte);
1675 return i ? : -EFAULT;
1676 }
1677 vma = get_gate_vma(mm);
1678 if (pages) {
1679 struct page *page;
1680
1681 page = vm_normal_page(vma, start, *pte);
1682 if (!page) {
1683 if (!(gup_flags & FOLL_DUMP) &&
1684 is_zero_pfn(pte_pfn(*pte)))
1685 page = pte_page(*pte);
1686 else {
1687 pte_unmap(pte);
1688 return i ? : -EFAULT;
1689 }
1690 }
1691 pages[i] = page;
1692 get_page(page);
1693 }
1694 pte_unmap(pte);
1695 goto next_page;
1696 }
1697
1698 if (!vma ||
1699 (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1700 !(vm_flags & vma->vm_flags))
1701 return i ? : -EFAULT;
1702
1703 if (is_vm_hugetlb_page(vma)) {
1704 i = follow_hugetlb_page(mm, vma, pages, vmas,
1705 &start, &nr_pages, i, gup_flags);
1706 continue;
1707 }
1708
1709 do {
1710 struct page *page;
1711 unsigned int foll_flags = gup_flags;
1712
1713 /*
1714 * If we have a pending SIGKILL, don't keep faulting
1715 * pages and potentially allocating memory.
1716 */
1717 if (unlikely(fatal_signal_pending(current)))
1718 return i ? i : -ERESTARTSYS;
1719
1720 cond_resched();
1721 while (!(page = follow_page(vma, start, foll_flags))) {
1722 int ret;
1723 unsigned int fault_flags = 0;
1724
1725 /* For mlock, just skip the stack guard page. */
1726 if (foll_flags & FOLL_MLOCK) {
1727 if (stack_guard_page(vma, start))
1728 goto next_page;
1729 }
1730 if (foll_flags & FOLL_WRITE)
1731 fault_flags |= FAULT_FLAG_WRITE;
1732 if (nonblocking)
1733 fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1734 if (foll_flags & FOLL_NOWAIT)
1735 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1736
1737 ret = handle_mm_fault(mm, vma, start,
1738 fault_flags);
1739
1740 if (ret & VM_FAULT_ERROR) {
1741 if (ret & VM_FAULT_OOM)
1742 return i ? i : -ENOMEM;
1743 if (ret & (VM_FAULT_HWPOISON |
1744 VM_FAULT_HWPOISON_LARGE)) {
1745 if (i)
1746 return i;
1747 else if (gup_flags & FOLL_HWPOISON)
1748 return -EHWPOISON;
1749 else
1750 return -EFAULT;
1751 }
1752 if (ret & VM_FAULT_SIGBUS)
1753 return i ? i : -EFAULT;
1754 BUG();
1755 }
1756
1757 if (tsk) {
1758 if (ret & VM_FAULT_MAJOR)
1759 tsk->maj_flt++;
1760 else
1761 tsk->min_flt++;
1762 }
1763
1764 if (ret & VM_FAULT_RETRY) {
1765 if (nonblocking)
1766 *nonblocking = 0;
1767 return i;
1768 }
1769
1770 /*
1771 * The VM_FAULT_WRITE bit tells us that
1772 * do_wp_page has broken COW when necessary,
1773 * even if maybe_mkwrite decided not to set
1774 * pte_write. We can thus safely do subsequent
1775 * page lookups as if they were reads. But only
1776 * do so when looping for pte_write is futile:
1777 * in some cases userspace may also be wanting
1778 * to write to the gotten user page, which a
1779 * read fault here might prevent (a readonly
1780 * page might get reCOWed by userspace write).
1781 */
1782 if ((ret & VM_FAULT_WRITE) &&
1783 !(vma->vm_flags & VM_WRITE))
1784 foll_flags &= ~FOLL_WRITE;
1785
1786 cond_resched();
1787 }
1788 if (IS_ERR(page))
1789 return i ? i : PTR_ERR(page);
1790 if (pages) {
1791 pages[i] = page;
1792
1793 flush_anon_page(vma, page, start);
1794 flush_dcache_page(page);
1795 }
1796next_page:
1797 if (vmas)
1798 vmas[i] = vma;
1799 i++;
1800 start += PAGE_SIZE;
1801 nr_pages--;
1802 } while (nr_pages && start < vma->vm_end);
1803 } while (nr_pages);
1804 return i;
1805}
1806EXPORT_SYMBOL(__get_user_pages);
1807
1808/*
1809 * fixup_user_fault() - manually resolve a user page fault
1810 * @tsk: the task_struct to use for page fault accounting, or
1811 * NULL if faults are not to be recorded.
1812 * @mm: mm_struct of target mm
1813 * @address: user address
1814 * @fault_flags:flags to pass down to handle_mm_fault()
1815 *
1816 * This is meant to be called in the specific scenario where for locking reasons
1817 * we try to access user memory in atomic context (within a pagefault_disable()
1818 * section), this returns -EFAULT, and we want to resolve the user fault before
1819 * trying again.
1820 *
1821 * Typically this is meant to be used by the futex code.
1822 *
1823 * The main difference with get_user_pages() is that this function will
1824 * unconditionally call handle_mm_fault() which will in turn perform all the
1825 * necessary SW fixup of the dirty and young bits in the PTE, while
1826 * handle_mm_fault() only guarantees to update these in the struct page.
1827 *
1828 * This is important for some architectures where those bits also gate the
1829 * access permission to the page because they are maintained in software. On
1830 * such architectures, gup() will not be enough to make a subsequent access
1831 * succeed.
1832 *
1833 * This should be called with the mm_sem held for read.
1834 */
1835int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1836 unsigned long address, unsigned int fault_flags)
1837{
1838 struct vm_area_struct *vma;
1839 int ret;
1840
1841 vma = find_extend_vma(mm, address);
1842 if (!vma || address < vma->vm_start)
1843 return -EFAULT;
1844
1845 ret = handle_mm_fault(mm, vma, address, fault_flags);
1846 if (ret & VM_FAULT_ERROR) {
1847 if (ret & VM_FAULT_OOM)
1848 return -ENOMEM;
1849 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1850 return -EHWPOISON;
1851 if (ret & VM_FAULT_SIGBUS)
1852 return -EFAULT;
1853 BUG();
1854 }
1855 if (tsk) {
1856 if (ret & VM_FAULT_MAJOR)
1857 tsk->maj_flt++;
1858 else
1859 tsk->min_flt++;
1860 }
1861 return 0;
1862}
1863
1864/*
1865 * get_user_pages() - pin user pages in memory
1866 * @tsk: the task_struct to use for page fault accounting, or
1867 * NULL if faults are not to be recorded.
1868 * @mm: mm_struct of target mm
1869 * @start: starting user address
1870 * @nr_pages: number of pages from start to pin
1871 * @write: whether pages will be written to by the caller
1872 * @force: whether to force write access even if user mapping is
1873 * readonly. This will result in the page being COWed even
1874 * in MAP_SHARED mappings. You do not want this.
1875 * @pages: array that receives pointers to the pages pinned.
1876 * Should be at least nr_pages long. Or NULL, if caller
1877 * only intends to ensure the pages are faulted in.
1878 * @vmas: array of pointers to vmas corresponding to each page.
1879 * Or NULL if the caller does not require them.
1880 *
1881 * Returns number of pages pinned. This may be fewer than the number
1882 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1883 * were pinned, returns -errno. Each page returned must be released
1884 * with a put_page() call when it is finished with. vmas will only
1885 * remain valid while mmap_sem is held.
1886 *
1887 * Must be called with mmap_sem held for read or write.
1888 *
1889 * get_user_pages walks a process's page tables and takes a reference to
1890 * each struct page that each user address corresponds to at a given
1891 * instant. That is, it takes the page that would be accessed if a user
1892 * thread accesses the given user virtual address at that instant.
1893 *
1894 * This does not guarantee that the page exists in the user mappings when
1895 * get_user_pages returns, and there may even be a completely different
1896 * page there in some cases (eg. if mmapped pagecache has been invalidated
1897 * and subsequently re faulted). However it does guarantee that the page
1898 * won't be freed completely. And mostly callers simply care that the page
1899 * contains data that was valid *at some point in time*. Typically, an IO
1900 * or similar operation cannot guarantee anything stronger anyway because
1901 * locks can't be held over the syscall boundary.
1902 *
1903 * If write=0, the page must not be written to. If the page is written to,
1904 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1905 * after the page is finished with, and before put_page is called.
1906 *
1907 * get_user_pages is typically used for fewer-copy IO operations, to get a
1908 * handle on the memory by some means other than accesses via the user virtual
1909 * addresses. The pages may be submitted for DMA to devices or accessed via
1910 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1911 * use the correct cache flushing APIs.
1912 *
1913 * See also get_user_pages_fast, for performance critical applications.
1914 */
1915int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1916 unsigned long start, int nr_pages, int write, int force,
1917 struct page **pages, struct vm_area_struct **vmas)
1918{
1919 int flags = FOLL_TOUCH;
1920
1921 if (pages)
1922 flags |= FOLL_GET;
1923 if (write)
1924 flags |= FOLL_WRITE;
1925 if (force)
1926 flags |= FOLL_FORCE;
1927
1928 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1929 NULL);
1930}
1931EXPORT_SYMBOL(get_user_pages);
1932
1933/**
1934 * get_dump_page() - pin user page in memory while writing it to core dump
1935 * @addr: user address
1936 *
1937 * Returns struct page pointer of user page pinned for dump,
1938 * to be freed afterwards by page_cache_release() or put_page().
1939 *
1940 * Returns NULL on any kind of failure - a hole must then be inserted into
1941 * the corefile, to preserve alignment with its headers; and also returns
1942 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1943 * allowing a hole to be left in the corefile to save diskspace.
1944 *
1945 * Called without mmap_sem, but after all other threads have been killed.
1946 */
1947#ifdef CONFIG_ELF_CORE
1948struct page *get_dump_page(unsigned long addr)
1949{
1950 struct vm_area_struct *vma;
1951 struct page *page;
1952
1953 if (__get_user_pages(current, current->mm, addr, 1,
1954 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1955 NULL) < 1)
1956 return NULL;
1957 flush_cache_page(vma, addr, page_to_pfn(page));
1958 return page;
1959}
1960#endif /* CONFIG_ELF_CORE */
1961
1962pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1963 spinlock_t **ptl)
1964{
1965 pgd_t * pgd = pgd_offset(mm, addr);
1966 pud_t * pud = pud_alloc(mm, pgd, addr);
1967 if (pud) {
1968 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1969 if (pmd) {
1970 VM_BUG_ON(pmd_trans_huge(*pmd));
1971 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1972 }
1973 }
1974 return NULL;
1975}
1976
1977/*
1978 * This is the old fallback for page remapping.
1979 *
1980 * For historical reasons, it only allows reserved pages. Only
1981 * old drivers should use this, and they needed to mark their
1982 * pages reserved for the old functions anyway.
1983 */
1984static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1985 struct page *page, pgprot_t prot)
1986{
1987 struct mm_struct *mm = vma->vm_mm;
1988 int retval;
1989 pte_t *pte;
1990 spinlock_t *ptl;
1991
1992 retval = -EINVAL;
1993 if (PageAnon(page))
1994 goto out;
1995 retval = -ENOMEM;
1996 flush_dcache_page(page);
1997 pte = get_locked_pte(mm, addr, &ptl);
1998 if (!pte)
1999 goto out;
2000 retval = -EBUSY;
2001 if (!pte_none(*pte))
2002 goto out_unlock;
2003
2004 /* Ok, finally just insert the thing.. */
2005 get_page(page);
2006 inc_mm_counter_fast(mm, MM_FILEPAGES);
2007 page_add_file_rmap(page);
2008 set_pte_at(mm, addr, pte, mk_pte(page, prot));
2009
2010 retval = 0;
2011 pte_unmap_unlock(pte, ptl);
2012 return retval;
2013out_unlock:
2014 pte_unmap_unlock(pte, ptl);
2015out:
2016 return retval;
2017}
2018
2019/**
2020 * vm_insert_page - insert single page into user vma
2021 * @vma: user vma to map to
2022 * @addr: target user address of this page
2023 * @page: source kernel page
2024 *
2025 * This allows drivers to insert individual pages they've allocated
2026 * into a user vma.
2027 *
2028 * The page has to be a nice clean _individual_ kernel allocation.
2029 * If you allocate a compound page, you need to have marked it as
2030 * such (__GFP_COMP), or manually just split the page up yourself
2031 * (see split_page()).
2032 *
2033 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2034 * took an arbitrary page protection parameter. This doesn't allow
2035 * that. Your vma protection will have to be set up correctly, which
2036 * means that if you want a shared writable mapping, you'd better
2037 * ask for a shared writable mapping!
2038 *
2039 * The page does not need to be reserved.
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 vma->vm_flags |= VM_INSERTPAGE;
2049 return insert_page(vma, addr, page, vma->vm_page_prot);
2050}
2051EXPORT_SYMBOL(vm_insert_page);
2052
2053static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2054 unsigned long pfn, pgprot_t prot)
2055{
2056 struct mm_struct *mm = vma->vm_mm;
2057 int retval;
2058 pte_t *pte, entry;
2059 spinlock_t *ptl;
2060
2061 retval = -ENOMEM;
2062 pte = get_locked_pte(mm, addr, &ptl);
2063 if (!pte)
2064 goto out;
2065 retval = -EBUSY;
2066 if (!pte_none(*pte))
2067 goto out_unlock;
2068
2069 /* Ok, finally just insert the thing.. */
2070 entry = pte_mkspecial(pfn_pte(pfn, prot));
2071 set_pte_at(mm, addr, pte, entry);
2072 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2073
2074 retval = 0;
2075out_unlock:
2076 pte_unmap_unlock(pte, ptl);
2077out:
2078 return retval;
2079}
2080
2081/**
2082 * vm_insert_pfn - insert single pfn into user vma
2083 * @vma: user vma to map to
2084 * @addr: target user address of this page
2085 * @pfn: source kernel pfn
2086 *
2087 * Similar to vm_inert_page, this allows drivers to insert individual pages
2088 * they've allocated into a user vma. Same comments apply.
2089 *
2090 * This function should only be called from a vm_ops->fault handler, and
2091 * in that case the handler should return NULL.
2092 *
2093 * vma cannot be a COW mapping.
2094 *
2095 * As this is called only for pages that do not currently exist, we
2096 * do not need to flush old virtual caches or the TLB.
2097 */
2098int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2099 unsigned long pfn)
2100{
2101 int ret;
2102 pgprot_t pgprot = vma->vm_page_prot;
2103 /*
2104 * Technically, architectures with pte_special can avoid all these
2105 * restrictions (same for remap_pfn_range). However we would like
2106 * consistency in testing and feature parity among all, so we should
2107 * try to keep these invariants in place for everybody.
2108 */
2109 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2110 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2111 (VM_PFNMAP|VM_MIXEDMAP));
2112 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2113 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2114
2115 if (addr < vma->vm_start || addr >= vma->vm_end)
2116 return -EFAULT;
2117 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2118 return -EINVAL;
2119
2120 ret = insert_pfn(vma, addr, pfn, pgprot);
2121
2122 if (ret)
2123 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2124
2125 return ret;
2126}
2127EXPORT_SYMBOL(vm_insert_pfn);
2128
2129int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2130 unsigned long pfn)
2131{
2132 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2133
2134 if (addr < vma->vm_start || addr >= vma->vm_end)
2135 return -EFAULT;
2136
2137 /*
2138 * If we don't have pte special, then we have to use the pfn_valid()
2139 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2140 * refcount the page if pfn_valid is true (hence insert_page rather
2141 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2142 * without pte special, it would there be refcounted as a normal page.
2143 */
2144 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2145 struct page *page;
2146
2147 page = pfn_to_page(pfn);
2148 return insert_page(vma, addr, page, vma->vm_page_prot);
2149 }
2150 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2151}
2152EXPORT_SYMBOL(vm_insert_mixed);
2153
2154/*
2155 * maps a range of physical memory into the requested pages. the old
2156 * mappings are removed. any references to nonexistent pages results
2157 * in null mappings (currently treated as "copy-on-access")
2158 */
2159static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2160 unsigned long addr, unsigned long end,
2161 unsigned long pfn, pgprot_t prot)
2162{
2163 pte_t *pte;
2164 spinlock_t *ptl;
2165
2166 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2167 if (!pte)
2168 return -ENOMEM;
2169 arch_enter_lazy_mmu_mode();
2170 do {
2171 BUG_ON(!pte_none(*pte));
2172 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2173 pfn++;
2174 } while (pte++, addr += PAGE_SIZE, addr != end);
2175 arch_leave_lazy_mmu_mode();
2176 pte_unmap_unlock(pte - 1, ptl);
2177 return 0;
2178}
2179
2180static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2181 unsigned long addr, unsigned long end,
2182 unsigned long pfn, pgprot_t prot)
2183{
2184 pmd_t *pmd;
2185 unsigned long next;
2186
2187 pfn -= addr >> PAGE_SHIFT;
2188 pmd = pmd_alloc(mm, pud, addr);
2189 if (!pmd)
2190 return -ENOMEM;
2191 VM_BUG_ON(pmd_trans_huge(*pmd));
2192 do {
2193 next = pmd_addr_end(addr, end);
2194 if (remap_pte_range(mm, pmd, addr, next,
2195 pfn + (addr >> PAGE_SHIFT), prot))
2196 return -ENOMEM;
2197 } while (pmd++, addr = next, addr != end);
2198 return 0;
2199}
2200
2201static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2202 unsigned long addr, unsigned long end,
2203 unsigned long pfn, pgprot_t prot)
2204{
2205 pud_t *pud;
2206 unsigned long next;
2207
2208 pfn -= addr >> PAGE_SHIFT;
2209 pud = pud_alloc(mm, pgd, addr);
2210 if (!pud)
2211 return -ENOMEM;
2212 do {
2213 next = pud_addr_end(addr, end);
2214 if (remap_pmd_range(mm, pud, addr, next,
2215 pfn + (addr >> PAGE_SHIFT), prot))
2216 return -ENOMEM;
2217 } while (pud++, addr = next, addr != end);
2218 return 0;
2219}
2220
2221/**
2222 * remap_pfn_range - remap kernel memory to userspace
2223 * @vma: user vma to map to
2224 * @addr: target user address to start at
2225 * @pfn: physical address of kernel memory
2226 * @size: size of map area
2227 * @prot: page protection flags for this mapping
2228 *
2229 * Note: this is only safe if the mm semaphore is held when called.
2230 */
2231int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2232 unsigned long pfn, unsigned long size, pgprot_t prot)
2233{
2234 pgd_t *pgd;
2235 unsigned long next;
2236 unsigned long end = addr + PAGE_ALIGN(size);
2237 struct mm_struct *mm = vma->vm_mm;
2238 int err;
2239
2240 /*
2241 * Physically remapped pages are special. Tell the
2242 * rest of the world about it:
2243 * VM_IO tells people not to look at these pages
2244 * (accesses can have side effects).
2245 * VM_RESERVED is specified all over the place, because
2246 * in 2.4 it kept swapout's vma scan off this vma; but
2247 * in 2.6 the LRU scan won't even find its pages, so this
2248 * flag means no more than count its pages in reserved_vm,
2249 * and omit it from core dump, even when VM_IO turned off.
2250 * VM_PFNMAP tells the core MM that the base pages are just
2251 * raw PFN mappings, and do not have a "struct page" associated
2252 * with them.
2253 *
2254 * There's a horrible special case to handle copy-on-write
2255 * behaviour that some programs depend on. We mark the "original"
2256 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2257 */
2258 if (addr == vma->vm_start && end == vma->vm_end) {
2259 vma->vm_pgoff = pfn;
2260 vma->vm_flags |= VM_PFN_AT_MMAP;
2261 } else if (is_cow_mapping(vma->vm_flags))
2262 return -EINVAL;
2263
2264 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2265
2266 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2267 if (err) {
2268 /*
2269 * To indicate that track_pfn related cleanup is not
2270 * needed from higher level routine calling unmap_vmas
2271 */
2272 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2273 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2274 return -EINVAL;
2275 }
2276
2277 BUG_ON(addr >= end);
2278 pfn -= addr >> PAGE_SHIFT;
2279 pgd = pgd_offset(mm, addr);
2280 flush_cache_range(vma, addr, end);
2281 do {
2282 next = pgd_addr_end(addr, end);
2283 err = remap_pud_range(mm, pgd, addr, next,
2284 pfn + (addr >> PAGE_SHIFT), prot);
2285 if (err)
2286 break;
2287 } while (pgd++, addr = next, addr != end);
2288
2289 if (err)
2290 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2291
2292 return err;
2293}
2294EXPORT_SYMBOL(remap_pfn_range);
2295
2296static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2297 unsigned long addr, unsigned long end,
2298 pte_fn_t fn, void *data)
2299{
2300 pte_t *pte;
2301 int err;
2302 pgtable_t token;
2303 spinlock_t *uninitialized_var(ptl);
2304
2305 pte = (mm == &init_mm) ?
2306 pte_alloc_kernel(pmd, addr) :
2307 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2308 if (!pte)
2309 return -ENOMEM;
2310
2311 BUG_ON(pmd_huge(*pmd));
2312
2313 arch_enter_lazy_mmu_mode();
2314
2315 token = pmd_pgtable(*pmd);
2316
2317 do {
2318 err = fn(pte++, token, addr, data);
2319 if (err)
2320 break;
2321 } while (addr += PAGE_SIZE, addr != end);
2322
2323 arch_leave_lazy_mmu_mode();
2324
2325 if (mm != &init_mm)
2326 pte_unmap_unlock(pte-1, ptl);
2327 return err;
2328}
2329
2330static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2331 unsigned long addr, unsigned long end,
2332 pte_fn_t fn, void *data)
2333{
2334 pmd_t *pmd;
2335 unsigned long next;
2336 int err;
2337
2338 BUG_ON(pud_huge(*pud));
2339
2340 pmd = pmd_alloc(mm, pud, addr);
2341 if (!pmd)
2342 return -ENOMEM;
2343 do {
2344 next = pmd_addr_end(addr, end);
2345 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2346 if (err)
2347 break;
2348 } while (pmd++, addr = next, addr != end);
2349 return err;
2350}
2351
2352static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2353 unsigned long addr, unsigned long end,
2354 pte_fn_t fn, void *data)
2355{
2356 pud_t *pud;
2357 unsigned long next;
2358 int err;
2359
2360 pud = pud_alloc(mm, pgd, addr);
2361 if (!pud)
2362 return -ENOMEM;
2363 do {
2364 next = pud_addr_end(addr, end);
2365 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2366 if (err)
2367 break;
2368 } while (pud++, addr = next, addr != end);
2369 return err;
2370}
2371
2372/*
2373 * Scan a region of virtual memory, filling in page tables as necessary
2374 * and calling a provided function on each leaf page table.
2375 */
2376int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2377 unsigned long size, pte_fn_t fn, void *data)
2378{
2379 pgd_t *pgd;
2380 unsigned long next;
2381 unsigned long end = addr + size;
2382 int err;
2383
2384 BUG_ON(addr >= end);
2385 pgd = pgd_offset(mm, addr);
2386 do {
2387 next = pgd_addr_end(addr, end);
2388 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2389 if (err)
2390 break;
2391 } while (pgd++, addr = next, addr != end);
2392
2393 return err;
2394}
2395EXPORT_SYMBOL_GPL(apply_to_page_range);
2396
2397/*
2398 * handle_pte_fault chooses page fault handler according to an entry
2399 * which was read non-atomically. Before making any commitment, on
2400 * those architectures or configurations (e.g. i386 with PAE) which
2401 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2402 * must check under lock before unmapping the pte and proceeding
2403 * (but do_wp_page is only called after already making such a check;
2404 * and do_anonymous_page can safely check later on).
2405 */
2406static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2407 pte_t *page_table, pte_t orig_pte)
2408{
2409 int same = 1;
2410#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2411 if (sizeof(pte_t) > sizeof(unsigned long)) {
2412 spinlock_t *ptl = pte_lockptr(mm, pmd);
2413 spin_lock(ptl);
2414 same = pte_same(*page_table, orig_pte);
2415 spin_unlock(ptl);
2416 }
2417#endif
2418 pte_unmap(page_table);
2419 return same;
2420}
2421
2422static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2423{
2424 /*
2425 * If the source page was a PFN mapping, we don't have
2426 * a "struct page" for it. We do a best-effort copy by
2427 * just copying from the original user address. If that
2428 * fails, we just zero-fill it. Live with it.
2429 */
2430 if (unlikely(!src)) {
2431 void *kaddr = kmap_atomic(dst, KM_USER0);
2432 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2433
2434 /*
2435 * This really shouldn't fail, because the page is there
2436 * in the page tables. But it might just be unreadable,
2437 * in which case we just give up and fill the result with
2438 * zeroes.
2439 */
2440 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2441 clear_page(kaddr);
2442 kunmap_atomic(kaddr, KM_USER0);
2443 flush_dcache_page(dst);
2444 } else
2445 copy_user_highpage(dst, src, va, vma);
2446}
2447
2448/*
2449 * This routine handles present pages, when users try to write
2450 * to a shared page. It is done by copying the page to a new address
2451 * and decrementing the shared-page counter for the old page.
2452 *
2453 * Note that this routine assumes that the protection checks have been
2454 * done by the caller (the low-level page fault routine in most cases).
2455 * Thus we can safely just mark it writable once we've done any necessary
2456 * COW.
2457 *
2458 * We also mark the page dirty at this point even though the page will
2459 * change only once the write actually happens. This avoids a few races,
2460 * and potentially makes it more efficient.
2461 *
2462 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2463 * but allow concurrent faults), with pte both mapped and locked.
2464 * We return with mmap_sem still held, but pte unmapped and unlocked.
2465 */
2466static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2467 unsigned long address, pte_t *page_table, pmd_t *pmd,
2468 spinlock_t *ptl, pte_t orig_pte)
2469 __releases(ptl)
2470{
2471 struct page *old_page, *new_page;
2472 pte_t entry;
2473 int ret = 0;
2474 int page_mkwrite = 0;
2475 struct page *dirty_page = NULL;
2476
2477 old_page = vm_normal_page(vma, address, orig_pte);
2478 if (!old_page) {
2479 /*
2480 * VM_MIXEDMAP !pfn_valid() case
2481 *
2482 * We should not cow pages in a shared writeable mapping.
2483 * Just mark the pages writable as we can't do any dirty
2484 * accounting on raw pfn maps.
2485 */
2486 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2487 (VM_WRITE|VM_SHARED))
2488 goto reuse;
2489 goto gotten;
2490 }
2491
2492 /*
2493 * Take out anonymous pages first, anonymous shared vmas are
2494 * not dirty accountable.
2495 */
2496 if (PageAnon(old_page) && !PageKsm(old_page)) {
2497 if (!trylock_page(old_page)) {
2498 page_cache_get(old_page);
2499 pte_unmap_unlock(page_table, ptl);
2500 lock_page(old_page);
2501 page_table = pte_offset_map_lock(mm, pmd, address,
2502 &ptl);
2503 if (!pte_same(*page_table, orig_pte)) {
2504 unlock_page(old_page);
2505 goto unlock;
2506 }
2507 page_cache_release(old_page);
2508 }
2509 if (reuse_swap_page(old_page)) {
2510 /*
2511 * The page is all ours. Move it to our anon_vma so
2512 * the rmap code will not search our parent or siblings.
2513 * Protected against the rmap code by the page lock.
2514 */
2515 page_move_anon_rmap(old_page, vma, address);
2516 unlock_page(old_page);
2517 goto reuse;
2518 }
2519 unlock_page(old_page);
2520 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2521 (VM_WRITE|VM_SHARED))) {
2522 /*
2523 * Only catch write-faults on shared writable pages,
2524 * read-only shared pages can get COWed by
2525 * get_user_pages(.write=1, .force=1).
2526 */
2527 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2528 struct vm_fault vmf;
2529 int tmp;
2530
2531 vmf.virtual_address = (void __user *)(address &
2532 PAGE_MASK);
2533 vmf.pgoff = old_page->index;
2534 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2535 vmf.page = old_page;
2536
2537 /*
2538 * Notify the address space that the page is about to
2539 * become writable so that it can prohibit this or wait
2540 * for the page to get into an appropriate state.
2541 *
2542 * We do this without the lock held, so that it can
2543 * sleep if it needs to.
2544 */
2545 page_cache_get(old_page);
2546 pte_unmap_unlock(page_table, ptl);
2547
2548 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2549 if (unlikely(tmp &
2550 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2551 ret = tmp;
2552 goto unwritable_page;
2553 }
2554 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2555 lock_page(old_page);
2556 if (!old_page->mapping) {
2557 ret = 0; /* retry the fault */
2558 unlock_page(old_page);
2559 goto unwritable_page;
2560 }
2561 } else
2562 VM_BUG_ON(!PageLocked(old_page));
2563
2564 /*
2565 * Since we dropped the lock we need to revalidate
2566 * the PTE as someone else may have changed it. If
2567 * they did, we just return, as we can count on the
2568 * MMU to tell us if they didn't also make it writable.
2569 */
2570 page_table = pte_offset_map_lock(mm, pmd, address,
2571 &ptl);
2572 if (!pte_same(*page_table, orig_pte)) {
2573 unlock_page(old_page);
2574 goto unlock;
2575 }
2576
2577 page_mkwrite = 1;
2578 }
2579 dirty_page = old_page;
2580 get_page(dirty_page);
2581
2582reuse:
2583 flush_cache_page(vma, address, pte_pfn(orig_pte));
2584 entry = pte_mkyoung(orig_pte);
2585 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2586 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2587 update_mmu_cache(vma, address, page_table);
2588 pte_unmap_unlock(page_table, ptl);
2589 ret |= VM_FAULT_WRITE;
2590
2591 if (!dirty_page)
2592 return ret;
2593
2594 /*
2595 * Yes, Virginia, this is actually required to prevent a race
2596 * with clear_page_dirty_for_io() from clearing the page dirty
2597 * bit after it clear all dirty ptes, but before a racing
2598 * do_wp_page installs a dirty pte.
2599 *
2600 * __do_fault is protected similarly.
2601 */
2602 if (!page_mkwrite) {
2603 wait_on_page_locked(dirty_page);
2604 set_page_dirty_balance(dirty_page, page_mkwrite);
2605 }
2606 put_page(dirty_page);
2607 if (page_mkwrite) {
2608 struct address_space *mapping = dirty_page->mapping;
2609
2610 set_page_dirty(dirty_page);
2611 unlock_page(dirty_page);
2612 page_cache_release(dirty_page);
2613 if (mapping) {
2614 /*
2615 * Some device drivers do not set page.mapping
2616 * but still dirty their pages
2617 */
2618 balance_dirty_pages_ratelimited(mapping);
2619 }
2620 }
2621
2622 /* file_update_time outside page_lock */
2623 if (vma->vm_file)
2624 file_update_time(vma->vm_file);
2625
2626 return ret;
2627 }
2628
2629 /*
2630 * Ok, we need to copy. Oh, well..
2631 */
2632 page_cache_get(old_page);
2633gotten:
2634 pte_unmap_unlock(page_table, ptl);
2635
2636 if (unlikely(anon_vma_prepare(vma)))
2637 goto oom;
2638
2639 if (is_zero_pfn(pte_pfn(orig_pte))) {
2640 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2641 if (!new_page)
2642 goto oom;
2643 } else {
2644 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2645 if (!new_page)
2646 goto oom;
2647 cow_user_page(new_page, old_page, address, vma);
2648 }
2649 __SetPageUptodate(new_page);
2650
2651 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2652 goto oom_free_new;
2653
2654 /*
2655 * Re-check the pte - we dropped the lock
2656 */
2657 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2658 if (likely(pte_same(*page_table, orig_pte))) {
2659 if (old_page) {
2660 if (!PageAnon(old_page)) {
2661 dec_mm_counter_fast(mm, MM_FILEPAGES);
2662 inc_mm_counter_fast(mm, MM_ANONPAGES);
2663 }
2664 } else
2665 inc_mm_counter_fast(mm, MM_ANONPAGES);
2666 flush_cache_page(vma, address, pte_pfn(orig_pte));
2667 entry = mk_pte(new_page, vma->vm_page_prot);
2668 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2669 /*
2670 * Clear the pte entry and flush it first, before updating the
2671 * pte with the new entry. This will avoid a race condition
2672 * seen in the presence of one thread doing SMC and another
2673 * thread doing COW.
2674 */
2675 ptep_clear_flush(vma, address, page_table);
2676 page_add_new_anon_rmap(new_page, vma, address);
2677 /*
2678 * We call the notify macro here because, when using secondary
2679 * mmu page tables (such as kvm shadow page tables), we want the
2680 * new page to be mapped directly into the secondary page table.
2681 */
2682 set_pte_at_notify(mm, address, page_table, entry);
2683 update_mmu_cache(vma, address, page_table);
2684 if (old_page) {
2685 /*
2686 * Only after switching the pte to the new page may
2687 * we remove the mapcount here. Otherwise another
2688 * process may come and find the rmap count decremented
2689 * before the pte is switched to the new page, and
2690 * "reuse" the old page writing into it while our pte
2691 * here still points into it and can be read by other
2692 * threads.
2693 *
2694 * The critical issue is to order this
2695 * page_remove_rmap with the ptp_clear_flush above.
2696 * Those stores are ordered by (if nothing else,)
2697 * the barrier present in the atomic_add_negative
2698 * in page_remove_rmap.
2699 *
2700 * Then the TLB flush in ptep_clear_flush ensures that
2701 * no process can access the old page before the
2702 * decremented mapcount is visible. And the old page
2703 * cannot be reused until after the decremented
2704 * mapcount is visible. So transitively, TLBs to
2705 * old page will be flushed before it can be reused.
2706 */
2707 page_remove_rmap(old_page);
2708 }
2709
2710 /* Free the old page.. */
2711 new_page = old_page;
2712 ret |= VM_FAULT_WRITE;
2713 } else
2714 mem_cgroup_uncharge_page(new_page);
2715
2716 if (new_page)
2717 page_cache_release(new_page);
2718unlock:
2719 pte_unmap_unlock(page_table, ptl);
2720 if (old_page) {
2721 /*
2722 * Don't let another task, with possibly unlocked vma,
2723 * keep the mlocked page.
2724 */
2725 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2726 lock_page(old_page); /* LRU manipulation */
2727 munlock_vma_page(old_page);
2728 unlock_page(old_page);
2729 }
2730 page_cache_release(old_page);
2731 }
2732 return ret;
2733oom_free_new:
2734 page_cache_release(new_page);
2735oom:
2736 if (old_page) {
2737 if (page_mkwrite) {
2738 unlock_page(old_page);
2739 page_cache_release(old_page);
2740 }
2741 page_cache_release(old_page);
2742 }
2743 return VM_FAULT_OOM;
2744
2745unwritable_page:
2746 page_cache_release(old_page);
2747 return ret;
2748}
2749
2750static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2751 unsigned long start_addr, unsigned long end_addr,
2752 struct zap_details *details)
2753{
2754 zap_page_range(vma, start_addr, end_addr - start_addr, details);
2755}
2756
2757static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2758 struct zap_details *details)
2759{
2760 struct vm_area_struct *vma;
2761 struct prio_tree_iter iter;
2762 pgoff_t vba, vea, zba, zea;
2763
2764 vma_prio_tree_foreach(vma, &iter, root,
2765 details->first_index, details->last_index) {
2766
2767 vba = vma->vm_pgoff;
2768 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2769 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2770 zba = details->first_index;
2771 if (zba < vba)
2772 zba = vba;
2773 zea = details->last_index;
2774 if (zea > vea)
2775 zea = vea;
2776
2777 unmap_mapping_range_vma(vma,
2778 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2779 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2780 details);
2781 }
2782}
2783
2784static inline void unmap_mapping_range_list(struct list_head *head,
2785 struct zap_details *details)
2786{
2787 struct vm_area_struct *vma;
2788
2789 /*
2790 * In nonlinear VMAs there is no correspondence between virtual address
2791 * offset and file offset. So we must perform an exhaustive search
2792 * across *all* the pages in each nonlinear VMA, not just the pages
2793 * whose virtual address lies outside the file truncation point.
2794 */
2795 list_for_each_entry(vma, head, shared.vm_set.list) {
2796 details->nonlinear_vma = vma;
2797 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2798 }
2799}
2800
2801/**
2802 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2803 * @mapping: the address space containing mmaps to be unmapped.
2804 * @holebegin: byte in first page to unmap, relative to the start of
2805 * the underlying file. This will be rounded down to a PAGE_SIZE
2806 * boundary. Note that this is different from truncate_pagecache(), which
2807 * must keep the partial page. In contrast, we must get rid of
2808 * partial pages.
2809 * @holelen: size of prospective hole in bytes. This will be rounded
2810 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2811 * end of the file.
2812 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2813 * but 0 when invalidating pagecache, don't throw away private data.
2814 */
2815void unmap_mapping_range(struct address_space *mapping,
2816 loff_t const holebegin, loff_t const holelen, int even_cows)
2817{
2818 struct zap_details details;
2819 pgoff_t hba = holebegin >> PAGE_SHIFT;
2820 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2821
2822 /* Check for overflow. */
2823 if (sizeof(holelen) > sizeof(hlen)) {
2824 long long holeend =
2825 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2826 if (holeend & ~(long long)ULONG_MAX)
2827 hlen = ULONG_MAX - hba + 1;
2828 }
2829
2830 details.check_mapping = even_cows? NULL: mapping;
2831 details.nonlinear_vma = NULL;
2832 details.first_index = hba;
2833 details.last_index = hba + hlen - 1;
2834 if (details.last_index < details.first_index)
2835 details.last_index = ULONG_MAX;
2836
2837
2838 mutex_lock(&mapping->i_mmap_mutex);
2839 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2840 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2841 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2842 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2843 mutex_unlock(&mapping->i_mmap_mutex);
2844}
2845EXPORT_SYMBOL(unmap_mapping_range);
2846
2847/*
2848 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2849 * but allow concurrent faults), and pte mapped but not yet locked.
2850 * We return with mmap_sem still held, but pte unmapped and unlocked.
2851 */
2852static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2853 unsigned long address, pte_t *page_table, pmd_t *pmd,
2854 unsigned int flags, pte_t orig_pte)
2855{
2856 spinlock_t *ptl;
2857 struct page *page, *swapcache = NULL;
2858 swp_entry_t entry;
2859 pte_t pte;
2860 int locked;
2861 struct mem_cgroup *ptr;
2862 int exclusive = 0;
2863 int ret = 0;
2864
2865 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2866 goto out;
2867
2868 entry = pte_to_swp_entry(orig_pte);
2869 if (unlikely(non_swap_entry(entry))) {
2870 if (is_migration_entry(entry)) {
2871 migration_entry_wait(mm, pmd, address);
2872 } else if (is_hwpoison_entry(entry)) {
2873 ret = VM_FAULT_HWPOISON;
2874 } else {
2875 print_bad_pte(vma, address, orig_pte, NULL);
2876 ret = VM_FAULT_SIGBUS;
2877 }
2878 goto out;
2879 }
2880 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2881 page = lookup_swap_cache(entry);
2882 if (!page) {
2883 grab_swap_token(mm); /* Contend for token _before_ read-in */
2884 page = swapin_readahead(entry,
2885 GFP_HIGHUSER_MOVABLE, vma, address);
2886 if (!page) {
2887 /*
2888 * Back out if somebody else faulted in this pte
2889 * while we released the pte lock.
2890 */
2891 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2892 if (likely(pte_same(*page_table, orig_pte)))
2893 ret = VM_FAULT_OOM;
2894 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2895 goto unlock;
2896 }
2897
2898 /* Had to read the page from swap area: Major fault */
2899 ret = VM_FAULT_MAJOR;
2900 count_vm_event(PGMAJFAULT);
2901 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2902 } else if (PageHWPoison(page)) {
2903 /*
2904 * hwpoisoned dirty swapcache pages are kept for killing
2905 * owner processes (which may be unknown at hwpoison time)
2906 */
2907 ret = VM_FAULT_HWPOISON;
2908 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2909 goto out_release;
2910 }
2911
2912 locked = lock_page_or_retry(page, mm, flags);
2913 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2914 if (!locked) {
2915 ret |= VM_FAULT_RETRY;
2916 goto out_release;
2917 }
2918
2919 /*
2920 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2921 * release the swapcache from under us. The page pin, and pte_same
2922 * test below, are not enough to exclude that. Even if it is still
2923 * swapcache, we need to check that the page's swap has not changed.
2924 */
2925 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2926 goto out_page;
2927
2928 if (ksm_might_need_to_copy(page, vma, address)) {
2929 swapcache = page;
2930 page = ksm_does_need_to_copy(page, vma, address);
2931
2932 if (unlikely(!page)) {
2933 ret = VM_FAULT_OOM;
2934 page = swapcache;
2935 swapcache = NULL;
2936 goto out_page;
2937 }
2938 }
2939
2940 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2941 ret = VM_FAULT_OOM;
2942 goto out_page;
2943 }
2944
2945 /*
2946 * Back out if somebody else already faulted in this pte.
2947 */
2948 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2949 if (unlikely(!pte_same(*page_table, orig_pte)))
2950 goto out_nomap;
2951
2952 if (unlikely(!PageUptodate(page))) {
2953 ret = VM_FAULT_SIGBUS;
2954 goto out_nomap;
2955 }
2956
2957 /*
2958 * The page isn't present yet, go ahead with the fault.
2959 *
2960 * Be careful about the sequence of operations here.
2961 * To get its accounting right, reuse_swap_page() must be called
2962 * while the page is counted on swap but not yet in mapcount i.e.
2963 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2964 * must be called after the swap_free(), or it will never succeed.
2965 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2966 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2967 * in page->private. In this case, a record in swap_cgroup is silently
2968 * discarded at swap_free().
2969 */
2970
2971 inc_mm_counter_fast(mm, MM_ANONPAGES);
2972 dec_mm_counter_fast(mm, MM_SWAPENTS);
2973 pte = mk_pte(page, vma->vm_page_prot);
2974 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2975 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2976 flags &= ~FAULT_FLAG_WRITE;
2977 ret |= VM_FAULT_WRITE;
2978 exclusive = 1;
2979 }
2980 flush_icache_page(vma, page);
2981 set_pte_at(mm, address, page_table, pte);
2982 do_page_add_anon_rmap(page, vma, address, exclusive);
2983 /* It's better to call commit-charge after rmap is established */
2984 mem_cgroup_commit_charge_swapin(page, ptr);
2985
2986 swap_free(entry);
2987 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2988 try_to_free_swap(page);
2989 unlock_page(page);
2990 if (swapcache) {
2991 /*
2992 * Hold the lock to avoid the swap entry to be reused
2993 * until we take the PT lock for the pte_same() check
2994 * (to avoid false positives from pte_same). For
2995 * further safety release the lock after the swap_free
2996 * so that the swap count won't change under a
2997 * parallel locked swapcache.
2998 */
2999 unlock_page(swapcache);
3000 page_cache_release(swapcache);
3001 }
3002
3003 if (flags & FAULT_FLAG_WRITE) {
3004 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3005 if (ret & VM_FAULT_ERROR)
3006 ret &= VM_FAULT_ERROR;
3007 goto out;
3008 }
3009
3010 /* No need to invalidate - it was non-present before */
3011 update_mmu_cache(vma, address, page_table);
3012unlock:
3013 pte_unmap_unlock(page_table, ptl);
3014out:
3015 return ret;
3016out_nomap:
3017 mem_cgroup_cancel_charge_swapin(ptr);
3018 pte_unmap_unlock(page_table, ptl);
3019out_page:
3020 unlock_page(page);
3021out_release:
3022 page_cache_release(page);
3023 if (swapcache) {
3024 unlock_page(swapcache);
3025 page_cache_release(swapcache);
3026 }
3027 return ret;
3028}
3029
3030/*
3031 * This is like a special single-page "expand_{down|up}wards()",
3032 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3033 * doesn't hit another vma.
3034 */
3035static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3036{
3037 address &= PAGE_MASK;
3038 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3039 struct vm_area_struct *prev = vma->vm_prev;
3040
3041 /*
3042 * Is there a mapping abutting this one below?
3043 *
3044 * That's only ok if it's the same stack mapping
3045 * that has gotten split..
3046 */
3047 if (prev && prev->vm_end == address)
3048 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3049
3050 expand_downwards(vma, address - PAGE_SIZE);
3051 }
3052 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3053 struct vm_area_struct *next = vma->vm_next;
3054
3055 /* As VM_GROWSDOWN but s/below/above/ */
3056 if (next && next->vm_start == address + PAGE_SIZE)
3057 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3058
3059 expand_upwards(vma, address + PAGE_SIZE);
3060 }
3061 return 0;
3062}
3063
3064/*
3065 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3066 * but allow concurrent faults), and pte mapped but not yet locked.
3067 * We return with mmap_sem still held, but pte unmapped and unlocked.
3068 */
3069static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3070 unsigned long address, pte_t *page_table, pmd_t *pmd,
3071 unsigned int flags)
3072{
3073 struct page *page;
3074 spinlock_t *ptl;
3075 pte_t entry;
3076
3077 pte_unmap(page_table);
3078
3079 /* Check if we need to add a guard page to the stack */
3080 if (check_stack_guard_page(vma, address) < 0)
3081 return VM_FAULT_SIGBUS;
3082
3083 /* Use the zero-page for reads */
3084 if (!(flags & FAULT_FLAG_WRITE)) {
3085 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3086 vma->vm_page_prot));
3087 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3088 if (!pte_none(*page_table))
3089 goto unlock;
3090 goto setpte;
3091 }
3092
3093 /* Allocate our own private page. */
3094 if (unlikely(anon_vma_prepare(vma)))
3095 goto oom;
3096 page = alloc_zeroed_user_highpage_movable(vma, address);
3097 if (!page)
3098 goto oom;
3099 __SetPageUptodate(page);
3100
3101 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3102 goto oom_free_page;
3103
3104 entry = mk_pte(page, vma->vm_page_prot);
3105 if (vma->vm_flags & VM_WRITE)
3106 entry = pte_mkwrite(pte_mkdirty(entry));
3107
3108 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3109 if (!pte_none(*page_table))
3110 goto release;
3111
3112 inc_mm_counter_fast(mm, MM_ANONPAGES);
3113 page_add_new_anon_rmap(page, vma, address);
3114setpte:
3115 set_pte_at(mm, address, page_table, entry);
3116
3117 /* No need to invalidate - it was non-present before */
3118 update_mmu_cache(vma, address, page_table);
3119unlock:
3120 pte_unmap_unlock(page_table, ptl);
3121 return 0;
3122release:
3123 mem_cgroup_uncharge_page(page);
3124 page_cache_release(page);
3125 goto unlock;
3126oom_free_page:
3127 page_cache_release(page);
3128oom:
3129 return VM_FAULT_OOM;
3130}
3131
3132/*
3133 * __do_fault() tries to create a new page mapping. It aggressively
3134 * tries to share with existing pages, but makes a separate copy if
3135 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3136 * the next page fault.
3137 *
3138 * As this is called only for pages that do not currently exist, we
3139 * do not need to flush old virtual caches or the TLB.
3140 *
3141 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3142 * but allow concurrent faults), and pte neither mapped nor locked.
3143 * We return with mmap_sem still held, but pte unmapped and unlocked.
3144 */
3145static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3146 unsigned long address, pmd_t *pmd,
3147 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3148{
3149 pte_t *page_table;
3150 spinlock_t *ptl;
3151 struct page *page;
3152 struct page *cow_page;
3153 pte_t entry;
3154 int anon = 0;
3155 struct page *dirty_page = NULL;
3156 struct vm_fault vmf;
3157 int ret;
3158 int page_mkwrite = 0;
3159
3160 /*
3161 * If we do COW later, allocate page befor taking lock_page()
3162 * on the file cache page. This will reduce lock holding time.
3163 */
3164 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3165
3166 if (unlikely(anon_vma_prepare(vma)))
3167 return VM_FAULT_OOM;
3168
3169 cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3170 if (!cow_page)
3171 return VM_FAULT_OOM;
3172
3173 if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3174 page_cache_release(cow_page);
3175 return VM_FAULT_OOM;
3176 }
3177 } else
3178 cow_page = NULL;
3179
3180 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3181 vmf.pgoff = pgoff;
3182 vmf.flags = flags;
3183 vmf.page = NULL;
3184
3185 ret = vma->vm_ops->fault(vma, &vmf);
3186 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3187 VM_FAULT_RETRY)))
3188 goto uncharge_out;
3189
3190 if (unlikely(PageHWPoison(vmf.page))) {
3191 if (ret & VM_FAULT_LOCKED)
3192 unlock_page(vmf.page);
3193 ret = VM_FAULT_HWPOISON;
3194 goto uncharge_out;
3195 }
3196
3197 /*
3198 * For consistency in subsequent calls, make the faulted page always
3199 * locked.
3200 */
3201 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3202 lock_page(vmf.page);
3203 else
3204 VM_BUG_ON(!PageLocked(vmf.page));
3205
3206 /*
3207 * Should we do an early C-O-W break?
3208 */
3209 page = vmf.page;
3210 if (flags & FAULT_FLAG_WRITE) {
3211 if (!(vma->vm_flags & VM_SHARED)) {
3212 page = cow_page;
3213 anon = 1;
3214 copy_user_highpage(page, vmf.page, address, vma);
3215 __SetPageUptodate(page);
3216 } else {
3217 /*
3218 * If the page will be shareable, see if the backing
3219 * address space wants to know that the page is about
3220 * to become writable
3221 */
3222 if (vma->vm_ops->page_mkwrite) {
3223 int tmp;
3224
3225 unlock_page(page);
3226 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3227 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3228 if (unlikely(tmp &
3229 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3230 ret = tmp;
3231 goto unwritable_page;
3232 }
3233 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3234 lock_page(page);
3235 if (!page->mapping) {
3236 ret = 0; /* retry the fault */
3237 unlock_page(page);
3238 goto unwritable_page;
3239 }
3240 } else
3241 VM_BUG_ON(!PageLocked(page));
3242 page_mkwrite = 1;
3243 }
3244 }
3245
3246 }
3247
3248 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3249
3250 /*
3251 * This silly early PAGE_DIRTY setting removes a race
3252 * due to the bad i386 page protection. But it's valid
3253 * for other architectures too.
3254 *
3255 * Note that if FAULT_FLAG_WRITE is set, we either now have
3256 * an exclusive copy of the page, or this is a shared mapping,
3257 * so we can make it writable and dirty to avoid having to
3258 * handle that later.
3259 */
3260 /* Only go through if we didn't race with anybody else... */
3261 if (likely(pte_same(*page_table, orig_pte))) {
3262 flush_icache_page(vma, page);
3263 entry = mk_pte(page, vma->vm_page_prot);
3264 if (flags & FAULT_FLAG_WRITE)
3265 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3266 if (anon) {
3267 inc_mm_counter_fast(mm, MM_ANONPAGES);
3268 page_add_new_anon_rmap(page, vma, address);
3269 } else {
3270 inc_mm_counter_fast(mm, MM_FILEPAGES);
3271 page_add_file_rmap(page);
3272 if (flags & FAULT_FLAG_WRITE) {
3273 dirty_page = page;
3274 get_page(dirty_page);
3275 }
3276 }
3277 set_pte_at(mm, address, page_table, entry);
3278
3279 /* no need to invalidate: a not-present page won't be cached */
3280 update_mmu_cache(vma, address, page_table);
3281 } else {
3282 if (cow_page)
3283 mem_cgroup_uncharge_page(cow_page);
3284 if (anon)
3285 page_cache_release(page);
3286 else
3287 anon = 1; /* no anon but release faulted_page */
3288 }
3289
3290 pte_unmap_unlock(page_table, ptl);
3291
3292 if (dirty_page) {
3293 struct address_space *mapping = page->mapping;
3294
3295 if (set_page_dirty(dirty_page))
3296 page_mkwrite = 1;
3297 unlock_page(dirty_page);
3298 put_page(dirty_page);
3299 if (page_mkwrite && mapping) {
3300 /*
3301 * Some device drivers do not set page.mapping but still
3302 * dirty their pages
3303 */
3304 balance_dirty_pages_ratelimited(mapping);
3305 }
3306
3307 /* file_update_time outside page_lock */
3308 if (vma->vm_file)
3309 file_update_time(vma->vm_file);
3310 } else {
3311 unlock_page(vmf.page);
3312 if (anon)
3313 page_cache_release(vmf.page);
3314 }
3315
3316 return ret;
3317
3318unwritable_page:
3319 page_cache_release(page);
3320 return ret;
3321uncharge_out:
3322 /* fs's fault handler get error */
3323 if (cow_page) {
3324 mem_cgroup_uncharge_page(cow_page);
3325 page_cache_release(cow_page);
3326 }
3327 return ret;
3328}
3329
3330static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3331 unsigned long address, pte_t *page_table, pmd_t *pmd,
3332 unsigned int flags, pte_t orig_pte)
3333{
3334 pgoff_t pgoff = (((address & PAGE_MASK)
3335 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3336
3337 pte_unmap(page_table);
3338 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3339}
3340
3341/*
3342 * Fault of a previously existing named mapping. Repopulate the pte
3343 * from the encoded file_pte if possible. This enables swappable
3344 * nonlinear vmas.
3345 *
3346 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3347 * but allow concurrent faults), and pte mapped but not yet locked.
3348 * We return with mmap_sem still held, but pte unmapped and unlocked.
3349 */
3350static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3351 unsigned long address, pte_t *page_table, pmd_t *pmd,
3352 unsigned int flags, pte_t orig_pte)
3353{
3354 pgoff_t pgoff;
3355
3356 flags |= FAULT_FLAG_NONLINEAR;
3357
3358 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3359 return 0;
3360
3361 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3362 /*
3363 * Page table corrupted: show pte and kill process.
3364 */
3365 print_bad_pte(vma, address, orig_pte, NULL);
3366 return VM_FAULT_SIGBUS;
3367 }
3368
3369 pgoff = pte_to_pgoff(orig_pte);
3370 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3371}
3372
3373/*
3374 * These routines also need to handle stuff like marking pages dirty
3375 * and/or accessed for architectures that don't do it in hardware (most
3376 * RISC architectures). The early dirtying is also good on the i386.
3377 *
3378 * There is also a hook called "update_mmu_cache()" that architectures
3379 * with external mmu caches can use to update those (ie the Sparc or
3380 * PowerPC hashed page tables that act as extended TLBs).
3381 *
3382 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3383 * but allow concurrent faults), and pte mapped but not yet locked.
3384 * We return with mmap_sem still held, but pte unmapped and unlocked.
3385 */
3386int handle_pte_fault(struct mm_struct *mm,
3387 struct vm_area_struct *vma, unsigned long address,
3388 pte_t *pte, pmd_t *pmd, unsigned int flags)
3389{
3390 pte_t entry;
3391 spinlock_t *ptl;
3392
3393 entry = *pte;
3394 if (!pte_present(entry)) {
3395 if (pte_none(entry)) {
3396 if (vma->vm_ops) {
3397 if (likely(vma->vm_ops->fault))
3398 return do_linear_fault(mm, vma, address,
3399 pte, pmd, flags, entry);
3400 }
3401 return do_anonymous_page(mm, vma, address,
3402 pte, pmd, flags);
3403 }
3404 if (pte_file(entry))
3405 return do_nonlinear_fault(mm, vma, address,
3406 pte, pmd, flags, entry);
3407 return do_swap_page(mm, vma, address,
3408 pte, pmd, flags, entry);
3409 }
3410
3411 ptl = pte_lockptr(mm, pmd);
3412 spin_lock(ptl);
3413 if (unlikely(!pte_same(*pte, entry)))
3414 goto unlock;
3415 if (flags & FAULT_FLAG_WRITE) {
3416 if (!pte_write(entry))
3417 return do_wp_page(mm, vma, address,
3418 pte, pmd, ptl, entry);
3419 entry = pte_mkdirty(entry);
3420 }
3421 entry = pte_mkyoung(entry);
3422 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3423 update_mmu_cache(vma, address, pte);
3424 } else {
3425 /*
3426 * This is needed only for protection faults but the arch code
3427 * is not yet telling us if this is a protection fault or not.
3428 * This still avoids useless tlb flushes for .text page faults
3429 * with threads.
3430 */
3431 if (flags & FAULT_FLAG_WRITE)
3432 flush_tlb_fix_spurious_fault(vma, address);
3433 }
3434unlock:
3435 pte_unmap_unlock(pte, ptl);
3436 return 0;
3437}
3438
3439/*
3440 * By the time we get here, we already hold the mm semaphore
3441 */
3442int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3443 unsigned long address, unsigned int flags)
3444{
3445 pgd_t *pgd;
3446 pud_t *pud;
3447 pmd_t *pmd;
3448 pte_t *pte;
3449
3450 __set_current_state(TASK_RUNNING);
3451
3452 count_vm_event(PGFAULT);
3453 mem_cgroup_count_vm_event(mm, PGFAULT);
3454
3455 /* do counter updates before entering really critical section. */
3456 check_sync_rss_stat(current);
3457
3458 if (unlikely(is_vm_hugetlb_page(vma)))
3459 return hugetlb_fault(mm, vma, address, flags);
3460
3461 pgd = pgd_offset(mm, address);
3462 pud = pud_alloc(mm, pgd, address);
3463 if (!pud)
3464 return VM_FAULT_OOM;
3465 pmd = pmd_alloc(mm, pud, address);
3466 if (!pmd)
3467 return VM_FAULT_OOM;
3468 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3469 if (!vma->vm_ops)
3470 return do_huge_pmd_anonymous_page(mm, vma, address,
3471 pmd, flags);
3472 } else {
3473 pmd_t orig_pmd = *pmd;
3474 barrier();
3475 if (pmd_trans_huge(orig_pmd)) {
3476 if (flags & FAULT_FLAG_WRITE &&
3477 !pmd_write(orig_pmd) &&
3478 !pmd_trans_splitting(orig_pmd))
3479 return do_huge_pmd_wp_page(mm, vma, address,
3480 pmd, orig_pmd);
3481 return 0;
3482 }
3483 }
3484
3485 /*
3486 * Use __pte_alloc instead of pte_alloc_map, because we can't
3487 * run pte_offset_map on the pmd, if an huge pmd could
3488 * materialize from under us from a different thread.
3489 */
3490 if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3491 return VM_FAULT_OOM;
3492 /* if an huge pmd materialized from under us just retry later */
3493 if (unlikely(pmd_trans_huge(*pmd)))
3494 return 0;
3495 /*
3496 * A regular pmd is established and it can't morph into a huge pmd
3497 * from under us anymore at this point because we hold the mmap_sem
3498 * read mode and khugepaged takes it in write mode. So now it's
3499 * safe to run pte_offset_map().
3500 */
3501 pte = pte_offset_map(pmd, address);
3502
3503 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3504}
3505
3506#ifndef __PAGETABLE_PUD_FOLDED
3507/*
3508 * Allocate page upper directory.
3509 * We've already handled the fast-path in-line.
3510 */
3511int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3512{
3513 pud_t *new = pud_alloc_one(mm, address);
3514 if (!new)
3515 return -ENOMEM;
3516
3517 smp_wmb(); /* See comment in __pte_alloc */
3518
3519 spin_lock(&mm->page_table_lock);
3520 if (pgd_present(*pgd)) /* Another has populated it */
3521 pud_free(mm, new);
3522 else
3523 pgd_populate(mm, pgd, new);
3524 spin_unlock(&mm->page_table_lock);
3525 return 0;
3526}
3527#endif /* __PAGETABLE_PUD_FOLDED */
3528
3529#ifndef __PAGETABLE_PMD_FOLDED
3530/*
3531 * Allocate page middle directory.
3532 * We've already handled the fast-path in-line.
3533 */
3534int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3535{
3536 pmd_t *new = pmd_alloc_one(mm, address);
3537 if (!new)
3538 return -ENOMEM;
3539
3540 smp_wmb(); /* See comment in __pte_alloc */
3541
3542 spin_lock(&mm->page_table_lock);
3543#ifndef __ARCH_HAS_4LEVEL_HACK
3544 if (pud_present(*pud)) /* Another has populated it */
3545 pmd_free(mm, new);
3546 else
3547 pud_populate(mm, pud, new);
3548#else
3549 if (pgd_present(*pud)) /* Another has populated it */
3550 pmd_free(mm, new);
3551 else
3552 pgd_populate(mm, pud, new);
3553#endif /* __ARCH_HAS_4LEVEL_HACK */
3554 spin_unlock(&mm->page_table_lock);
3555 return 0;
3556}
3557#endif /* __PAGETABLE_PMD_FOLDED */
3558
3559int make_pages_present(unsigned long addr, unsigned long end)
3560{
3561 int ret, len, write;
3562 struct vm_area_struct * vma;
3563
3564 vma = find_vma(current->mm, addr);
3565 if (!vma)
3566 return -ENOMEM;
3567 /*
3568 * We want to touch writable mappings with a write fault in order
3569 * to break COW, except for shared mappings because these don't COW
3570 * and we would not want to dirty them for nothing.
3571 */
3572 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3573 BUG_ON(addr >= end);
3574 BUG_ON(end > vma->vm_end);
3575 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3576 ret = get_user_pages(current, current->mm, addr,
3577 len, write, 0, NULL, NULL);
3578 if (ret < 0)
3579 return ret;
3580 return ret == len ? 0 : -EFAULT;
3581}
3582
3583#if !defined(__HAVE_ARCH_GATE_AREA)
3584
3585#if defined(AT_SYSINFO_EHDR)
3586static struct vm_area_struct gate_vma;
3587
3588static int __init gate_vma_init(void)
3589{
3590 gate_vma.vm_mm = NULL;
3591 gate_vma.vm_start = FIXADDR_USER_START;
3592 gate_vma.vm_end = FIXADDR_USER_END;
3593 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3594 gate_vma.vm_page_prot = __P101;
3595 /*
3596 * Make sure the vDSO gets into every core dump.
3597 * Dumping its contents makes post-mortem fully interpretable later
3598 * without matching up the same kernel and hardware config to see
3599 * what PC values meant.
3600 */
3601 gate_vma.vm_flags |= VM_ALWAYSDUMP;
3602 return 0;
3603}
3604__initcall(gate_vma_init);
3605#endif
3606
3607struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3608{
3609#ifdef AT_SYSINFO_EHDR
3610 return &gate_vma;
3611#else
3612 return NULL;
3613#endif
3614}
3615
3616int in_gate_area_no_mm(unsigned long addr)
3617{
3618#ifdef AT_SYSINFO_EHDR
3619 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3620 return 1;
3621#endif
3622 return 0;
3623}
3624
3625#endif /* __HAVE_ARCH_GATE_AREA */
3626
3627static int __follow_pte(struct mm_struct *mm, unsigned long address,
3628 pte_t **ptepp, spinlock_t **ptlp)
3629{
3630 pgd_t *pgd;
3631 pud_t *pud;
3632 pmd_t *pmd;
3633 pte_t *ptep;
3634
3635 pgd = pgd_offset(mm, address);
3636 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3637 goto out;
3638
3639 pud = pud_offset(pgd, address);
3640 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3641 goto out;
3642
3643 pmd = pmd_offset(pud, address);
3644 VM_BUG_ON(pmd_trans_huge(*pmd));
3645 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3646 goto out;
3647
3648 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3649 if (pmd_huge(*pmd))
3650 goto out;
3651
3652 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3653 if (!ptep)
3654 goto out;
3655 if (!pte_present(*ptep))
3656 goto unlock;
3657 *ptepp = ptep;
3658 return 0;
3659unlock:
3660 pte_unmap_unlock(ptep, *ptlp);
3661out:
3662 return -EINVAL;
3663}
3664
3665static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3666 pte_t **ptepp, spinlock_t **ptlp)
3667{
3668 int res;
3669
3670 /* (void) is needed to make gcc happy */
3671 (void) __cond_lock(*ptlp,
3672 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3673 return res;
3674}
3675
3676/**
3677 * follow_pfn - look up PFN at a user virtual address
3678 * @vma: memory mapping
3679 * @address: user virtual address
3680 * @pfn: location to store found PFN
3681 *
3682 * Only IO mappings and raw PFN mappings are allowed.
3683 *
3684 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3685 */
3686int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3687 unsigned long *pfn)
3688{
3689 int ret = -EINVAL;
3690 spinlock_t *ptl;
3691 pte_t *ptep;
3692
3693 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3694 return ret;
3695
3696 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3697 if (ret)
3698 return ret;
3699 *pfn = pte_pfn(*ptep);
3700 pte_unmap_unlock(ptep, ptl);
3701 return 0;
3702}
3703EXPORT_SYMBOL(follow_pfn);
3704
3705#ifdef CONFIG_HAVE_IOREMAP_PROT
3706int follow_phys(struct vm_area_struct *vma,
3707 unsigned long address, unsigned int flags,
3708 unsigned long *prot, resource_size_t *phys)
3709{
3710 int ret = -EINVAL;
3711 pte_t *ptep, pte;
3712 spinlock_t *ptl;
3713
3714 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3715 goto out;
3716
3717 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3718 goto out;
3719 pte = *ptep;
3720
3721 if ((flags & FOLL_WRITE) && !pte_write(pte))
3722 goto unlock;
3723
3724 *prot = pgprot_val(pte_pgprot(pte));
3725 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3726
3727 ret = 0;
3728unlock:
3729 pte_unmap_unlock(ptep, ptl);
3730out:
3731 return ret;
3732}
3733
3734int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3735 void *buf, int len, int write)
3736{
3737 resource_size_t phys_addr;
3738 unsigned long prot = 0;
3739 void __iomem *maddr;
3740 int offset = addr & (PAGE_SIZE-1);
3741
3742 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3743 return -EINVAL;
3744
3745 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3746 if (write)
3747 memcpy_toio(maddr + offset, buf, len);
3748 else
3749 memcpy_fromio(buf, maddr + offset, len);
3750 iounmap(maddr);
3751
3752 return len;
3753}
3754#endif
3755
3756/*
3757 * Access another process' address space as given in mm. If non-NULL, use the
3758 * given task for page fault accounting.
3759 */
3760static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3761 unsigned long addr, void *buf, int len, int write)
3762{
3763 struct vm_area_struct *vma;
3764 void *old_buf = buf;
3765
3766 down_read(&mm->mmap_sem);
3767 /* ignore errors, just check how much was successfully transferred */
3768 while (len) {
3769 int bytes, ret, offset;
3770 void *maddr;
3771 struct page *page = NULL;
3772
3773 ret = get_user_pages(tsk, mm, addr, 1,
3774 write, 1, &page, &vma);
3775 if (ret <= 0) {
3776 /*
3777 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3778 * we can access using slightly different code.
3779 */
3780#ifdef CONFIG_HAVE_IOREMAP_PROT
3781 vma = find_vma(mm, addr);
3782 if (!vma || vma->vm_start > addr)
3783 break;
3784 if (vma->vm_ops && vma->vm_ops->access)
3785 ret = vma->vm_ops->access(vma, addr, buf,
3786 len, write);
3787 if (ret <= 0)
3788#endif
3789 break;
3790 bytes = ret;
3791 } else {
3792 bytes = len;
3793 offset = addr & (PAGE_SIZE-1);
3794 if (bytes > PAGE_SIZE-offset)
3795 bytes = PAGE_SIZE-offset;
3796
3797 maddr = kmap(page);
3798 if (write) {
3799 copy_to_user_page(vma, page, addr,
3800 maddr + offset, buf, bytes);
3801 set_page_dirty_lock(page);
3802 } else {
3803 copy_from_user_page(vma, page, addr,
3804 buf, maddr + offset, bytes);
3805 }
3806 kunmap(page);
3807 page_cache_release(page);
3808 }
3809 len -= bytes;
3810 buf += bytes;
3811 addr += bytes;
3812 }
3813 up_read(&mm->mmap_sem);
3814
3815 return buf - old_buf;
3816}
3817
3818/**
3819 * access_remote_vm - access another process' address space
3820 * @mm: the mm_struct of the target address space
3821 * @addr: start address to access
3822 * @buf: source or destination buffer
3823 * @len: number of bytes to transfer
3824 * @write: whether the access is a write
3825 *
3826 * The caller must hold a reference on @mm.
3827 */
3828int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3829 void *buf, int len, int write)
3830{
3831 return __access_remote_vm(NULL, mm, addr, buf, len, write);
3832}
3833
3834/*
3835 * Access another process' address space.
3836 * Source/target buffer must be kernel space,
3837 * Do not walk the page table directly, use get_user_pages
3838 */
3839int access_process_vm(struct task_struct *tsk, unsigned long addr,
3840 void *buf, int len, int write)
3841{
3842 struct mm_struct *mm;
3843 int ret;
3844
3845 mm = get_task_mm(tsk);
3846 if (!mm)
3847 return 0;
3848
3849 ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3850 mmput(mm);
3851
3852 return ret;
3853}
3854
3855/*
3856 * Print the name of a VMA.
3857 */
3858void print_vma_addr(char *prefix, unsigned long ip)
3859{
3860 struct mm_struct *mm = current->mm;
3861 struct vm_area_struct *vma;
3862
3863 /*
3864 * Do not print if we are in atomic
3865 * contexts (in exception stacks, etc.):
3866 */
3867 if (preempt_count())
3868 return;
3869
3870 down_read(&mm->mmap_sem);
3871 vma = find_vma(mm, ip);
3872 if (vma && vma->vm_file) {
3873 struct file *f = vma->vm_file;
3874 char *buf = (char *)__get_free_page(GFP_KERNEL);
3875 if (buf) {
3876 char *p, *s;
3877
3878 p = d_path(&f->f_path, buf, PAGE_SIZE);
3879 if (IS_ERR(p))
3880 p = "?";
3881 s = strrchr(p, '/');
3882 if (s)
3883 p = s+1;
3884 printk("%s%s[%lx+%lx]", prefix, p,
3885 vma->vm_start,
3886 vma->vm_end - vma->vm_start);
3887 free_page((unsigned long)buf);
3888 }
3889 }
3890 up_read(¤t->mm->mmap_sem);
3891}
3892
3893#ifdef CONFIG_PROVE_LOCKING
3894void might_fault(void)
3895{
3896 /*
3897 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3898 * holding the mmap_sem, this is safe because kernel memory doesn't
3899 * get paged out, therefore we'll never actually fault, and the
3900 * below annotations will generate false positives.
3901 */
3902 if (segment_eq(get_fs(), KERNEL_DS))
3903 return;
3904
3905 might_sleep();
3906 /*
3907 * it would be nicer only to annotate paths which are not under
3908 * pagefault_disable, however that requires a larger audit and
3909 * providing helpers like get_user_atomic.
3910 */
3911 if (!in_atomic() && current->mm)
3912 might_lock_read(¤t->mm->mmap_sem);
3913}
3914EXPORT_SYMBOL(might_fault);
3915#endif
3916
3917#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3918static void clear_gigantic_page(struct page *page,
3919 unsigned long addr,
3920 unsigned int pages_per_huge_page)
3921{
3922 int i;
3923 struct page *p = page;
3924
3925 might_sleep();
3926 for (i = 0; i < pages_per_huge_page;
3927 i++, p = mem_map_next(p, page, i)) {
3928 cond_resched();
3929 clear_user_highpage(p, addr + i * PAGE_SIZE);
3930 }
3931}
3932void clear_huge_page(struct page *page,
3933 unsigned long addr, unsigned int pages_per_huge_page)
3934{
3935 int i;
3936
3937 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3938 clear_gigantic_page(page, addr, pages_per_huge_page);
3939 return;
3940 }
3941
3942 might_sleep();
3943 for (i = 0; i < pages_per_huge_page; i++) {
3944 cond_resched();
3945 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3946 }
3947}
3948
3949static void copy_user_gigantic_page(struct page *dst, struct page *src,
3950 unsigned long addr,
3951 struct vm_area_struct *vma,
3952 unsigned int pages_per_huge_page)
3953{
3954 int i;
3955 struct page *dst_base = dst;
3956 struct page *src_base = src;
3957
3958 for (i = 0; i < pages_per_huge_page; ) {
3959 cond_resched();
3960 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3961
3962 i++;
3963 dst = mem_map_next(dst, dst_base, i);
3964 src = mem_map_next(src, src_base, i);
3965 }
3966}
3967
3968void copy_user_huge_page(struct page *dst, struct page *src,
3969 unsigned long addr, struct vm_area_struct *vma,
3970 unsigned int pages_per_huge_page)
3971{
3972 int i;
3973
3974 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3975 copy_user_gigantic_page(dst, src, addr, vma,
3976 pages_per_huge_page);
3977 return;
3978 }
3979
3980 might_sleep();
3981 for (i = 0; i < pages_per_huge_page; i++) {
3982 cond_resched();
3983 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3984 }
3985}
3986#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */