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