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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/dma-debug.h>
69#include <linux/debugfs.h>
70#include <linux/userfaultfd_k.h>
71#include <linux/dax.h>
72#include <linux/oom.h>
73#include <linux/numa.h>
74#include <linux/perf_event.h>
75#include <linux/ptrace.h>
76#include <linux/vmalloc.h>
77
78#include <trace/events/kmem.h>
79
80#include <asm/io.h>
81#include <asm/mmu_context.h>
82#include <asm/pgalloc.h>
83#include <linux/uaccess.h>
84#include <asm/tlb.h>
85#include <asm/tlbflush.h>
86
87#include "pgalloc-track.h"
88#include "internal.h"
89
90#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
91#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
92#endif
93
94#ifndef CONFIG_NEED_MULTIPLE_NODES
95/* use the per-pgdat data instead for discontigmem - mbligh */
96unsigned long max_mapnr;
97EXPORT_SYMBOL(max_mapnr);
98
99struct page *mem_map;
100EXPORT_SYMBOL(mem_map);
101#endif
102
103/*
104 * A number of key systems in x86 including ioremap() rely on the assumption
105 * that high_memory defines the upper bound on direct map memory, then end
106 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
107 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
108 * and ZONE_HIGHMEM.
109 */
110void *high_memory;
111EXPORT_SYMBOL(high_memory);
112
113/*
114 * Randomize the address space (stacks, mmaps, brk, etc.).
115 *
116 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
117 * as ancient (libc5 based) binaries can segfault. )
118 */
119int randomize_va_space __read_mostly =
120#ifdef CONFIG_COMPAT_BRK
121 1;
122#else
123 2;
124#endif
125
126#ifndef arch_faults_on_old_pte
127static inline bool arch_faults_on_old_pte(void)
128{
129 /*
130 * Those arches which don't have hw access flag feature need to
131 * implement their own helper. By default, "true" means pagefault
132 * will be hit on old pte.
133 */
134 return true;
135}
136#endif
137
138static int __init disable_randmaps(char *s)
139{
140 randomize_va_space = 0;
141 return 1;
142}
143__setup("norandmaps", disable_randmaps);
144
145unsigned long zero_pfn __read_mostly;
146EXPORT_SYMBOL(zero_pfn);
147
148unsigned long highest_memmap_pfn __read_mostly;
149
150/*
151 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
152 */
153static int __init init_zero_pfn(void)
154{
155 zero_pfn = page_to_pfn(ZERO_PAGE(0));
156 return 0;
157}
158core_initcall(init_zero_pfn);
159
160void mm_trace_rss_stat(struct mm_struct *mm, int member, long count)
161{
162 trace_rss_stat(mm, member, count);
163}
164
165#if defined(SPLIT_RSS_COUNTING)
166
167void sync_mm_rss(struct mm_struct *mm)
168{
169 int i;
170
171 for (i = 0; i < NR_MM_COUNTERS; i++) {
172 if (current->rss_stat.count[i]) {
173 add_mm_counter(mm, i, current->rss_stat.count[i]);
174 current->rss_stat.count[i] = 0;
175 }
176 }
177 current->rss_stat.events = 0;
178}
179
180static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
181{
182 struct task_struct *task = current;
183
184 if (likely(task->mm == mm))
185 task->rss_stat.count[member] += val;
186 else
187 add_mm_counter(mm, member, val);
188}
189#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
190#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
191
192/* sync counter once per 64 page faults */
193#define TASK_RSS_EVENTS_THRESH (64)
194static void check_sync_rss_stat(struct task_struct *task)
195{
196 if (unlikely(task != current))
197 return;
198 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
199 sync_mm_rss(task->mm);
200}
201#else /* SPLIT_RSS_COUNTING */
202
203#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
204#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
205
206static void check_sync_rss_stat(struct task_struct *task)
207{
208}
209
210#endif /* SPLIT_RSS_COUNTING */
211
212/*
213 * Note: this doesn't free the actual pages themselves. That
214 * has been handled earlier when unmapping all the memory regions.
215 */
216static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
217 unsigned long addr)
218{
219 pgtable_t token = pmd_pgtable(*pmd);
220 pmd_clear(pmd);
221 pte_free_tlb(tlb, token, addr);
222 mm_dec_nr_ptes(tlb->mm);
223}
224
225static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
226 unsigned long addr, unsigned long end,
227 unsigned long floor, unsigned long ceiling)
228{
229 pmd_t *pmd;
230 unsigned long next;
231 unsigned long start;
232
233 start = addr;
234 pmd = pmd_offset(pud, addr);
235 do {
236 next = pmd_addr_end(addr, end);
237 if (pmd_none_or_clear_bad(pmd))
238 continue;
239 free_pte_range(tlb, pmd, addr);
240 } while (pmd++, addr = next, addr != end);
241
242 start &= PUD_MASK;
243 if (start < floor)
244 return;
245 if (ceiling) {
246 ceiling &= PUD_MASK;
247 if (!ceiling)
248 return;
249 }
250 if (end - 1 > ceiling - 1)
251 return;
252
253 pmd = pmd_offset(pud, start);
254 pud_clear(pud);
255 pmd_free_tlb(tlb, pmd, start);
256 mm_dec_nr_pmds(tlb->mm);
257}
258
259static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
260 unsigned long addr, unsigned long end,
261 unsigned long floor, unsigned long ceiling)
262{
263 pud_t *pud;
264 unsigned long next;
265 unsigned long start;
266
267 start = addr;
268 pud = pud_offset(p4d, addr);
269 do {
270 next = pud_addr_end(addr, end);
271 if (pud_none_or_clear_bad(pud))
272 continue;
273 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
274 } while (pud++, addr = next, addr != end);
275
276 start &= P4D_MASK;
277 if (start < floor)
278 return;
279 if (ceiling) {
280 ceiling &= P4D_MASK;
281 if (!ceiling)
282 return;
283 }
284 if (end - 1 > ceiling - 1)
285 return;
286
287 pud = pud_offset(p4d, start);
288 p4d_clear(p4d);
289 pud_free_tlb(tlb, pud, start);
290 mm_dec_nr_puds(tlb->mm);
291}
292
293static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
294 unsigned long addr, unsigned long end,
295 unsigned long floor, unsigned long ceiling)
296{
297 p4d_t *p4d;
298 unsigned long next;
299 unsigned long start;
300
301 start = addr;
302 p4d = p4d_offset(pgd, addr);
303 do {
304 next = p4d_addr_end(addr, end);
305 if (p4d_none_or_clear_bad(p4d))
306 continue;
307 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
308 } while (p4d++, addr = next, addr != end);
309
310 start &= PGDIR_MASK;
311 if (start < floor)
312 return;
313 if (ceiling) {
314 ceiling &= PGDIR_MASK;
315 if (!ceiling)
316 return;
317 }
318 if (end - 1 > ceiling - 1)
319 return;
320
321 p4d = p4d_offset(pgd, start);
322 pgd_clear(pgd);
323 p4d_free_tlb(tlb, p4d, start);
324}
325
326/*
327 * This function frees user-level page tables of a process.
328 */
329void free_pgd_range(struct mmu_gather *tlb,
330 unsigned long addr, unsigned long end,
331 unsigned long floor, unsigned long ceiling)
332{
333 pgd_t *pgd;
334 unsigned long next;
335
336 /*
337 * The next few lines have given us lots of grief...
338 *
339 * Why are we testing PMD* at this top level? Because often
340 * there will be no work to do at all, and we'd prefer not to
341 * go all the way down to the bottom just to discover that.
342 *
343 * Why all these "- 1"s? Because 0 represents both the bottom
344 * of the address space and the top of it (using -1 for the
345 * top wouldn't help much: the masks would do the wrong thing).
346 * The rule is that addr 0 and floor 0 refer to the bottom of
347 * the address space, but end 0 and ceiling 0 refer to the top
348 * Comparisons need to use "end - 1" and "ceiling - 1" (though
349 * that end 0 case should be mythical).
350 *
351 * Wherever addr is brought up or ceiling brought down, we must
352 * be careful to reject "the opposite 0" before it confuses the
353 * subsequent tests. But what about where end is brought down
354 * by PMD_SIZE below? no, end can't go down to 0 there.
355 *
356 * Whereas we round start (addr) and ceiling down, by different
357 * masks at different levels, in order to test whether a table
358 * now has no other vmas using it, so can be freed, we don't
359 * bother to round floor or end up - the tests don't need that.
360 */
361
362 addr &= PMD_MASK;
363 if (addr < floor) {
364 addr += PMD_SIZE;
365 if (!addr)
366 return;
367 }
368 if (ceiling) {
369 ceiling &= PMD_MASK;
370 if (!ceiling)
371 return;
372 }
373 if (end - 1 > ceiling - 1)
374 end -= PMD_SIZE;
375 if (addr > end - 1)
376 return;
377 /*
378 * We add page table cache pages with PAGE_SIZE,
379 * (see pte_free_tlb()), flush the tlb if we need
380 */
381 tlb_change_page_size(tlb, PAGE_SIZE);
382 pgd = pgd_offset(tlb->mm, addr);
383 do {
384 next = pgd_addr_end(addr, end);
385 if (pgd_none_or_clear_bad(pgd))
386 continue;
387 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
388 } while (pgd++, addr = next, addr != end);
389}
390
391void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
392 unsigned long floor, unsigned long ceiling)
393{
394 while (vma) {
395 struct vm_area_struct *next = vma->vm_next;
396 unsigned long addr = vma->vm_start;
397
398 /*
399 * Hide vma from rmap and truncate_pagecache before freeing
400 * pgtables
401 */
402 unlink_anon_vmas(vma);
403 unlink_file_vma(vma);
404
405 if (is_vm_hugetlb_page(vma)) {
406 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
407 floor, next ? next->vm_start : ceiling);
408 } else {
409 /*
410 * Optimization: gather nearby vmas into one call down
411 */
412 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
413 && !is_vm_hugetlb_page(next)) {
414 vma = next;
415 next = vma->vm_next;
416 unlink_anon_vmas(vma);
417 unlink_file_vma(vma);
418 }
419 free_pgd_range(tlb, addr, vma->vm_end,
420 floor, next ? next->vm_start : ceiling);
421 }
422 vma = next;
423 }
424}
425
426int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
427{
428 spinlock_t *ptl;
429 pgtable_t new = pte_alloc_one(mm);
430 if (!new)
431 return -ENOMEM;
432
433 /*
434 * Ensure all pte setup (eg. pte page lock and page clearing) are
435 * visible before the pte is made visible to other CPUs by being
436 * put into page tables.
437 *
438 * The other side of the story is the pointer chasing in the page
439 * table walking code (when walking the page table without locking;
440 * ie. most of the time). Fortunately, these data accesses consist
441 * of a chain of data-dependent loads, meaning most CPUs (alpha
442 * being the notable exception) will already guarantee loads are
443 * seen in-order. See the alpha page table accessors for the
444 * smp_rmb() barriers in page table walking code.
445 */
446 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
447
448 ptl = pmd_lock(mm, pmd);
449 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
450 mm_inc_nr_ptes(mm);
451 pmd_populate(mm, pmd, new);
452 new = NULL;
453 }
454 spin_unlock(ptl);
455 if (new)
456 pte_free(mm, new);
457 return 0;
458}
459
460int __pte_alloc_kernel(pmd_t *pmd)
461{
462 pte_t *new = pte_alloc_one_kernel(&init_mm);
463 if (!new)
464 return -ENOMEM;
465
466 smp_wmb(); /* See comment in __pte_alloc */
467
468 spin_lock(&init_mm.page_table_lock);
469 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
470 pmd_populate_kernel(&init_mm, pmd, new);
471 new = NULL;
472 }
473 spin_unlock(&init_mm.page_table_lock);
474 if (new)
475 pte_free_kernel(&init_mm, new);
476 return 0;
477}
478
479static inline void init_rss_vec(int *rss)
480{
481 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
482}
483
484static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
485{
486 int i;
487
488 if (current->mm == mm)
489 sync_mm_rss(mm);
490 for (i = 0; i < NR_MM_COUNTERS; i++)
491 if (rss[i])
492 add_mm_counter(mm, i, rss[i]);
493}
494
495/*
496 * This function is called to print an error when a bad pte
497 * is found. For example, we might have a PFN-mapped pte in
498 * a region that doesn't allow it.
499 *
500 * The calling function must still handle the error.
501 */
502static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
503 pte_t pte, struct page *page)
504{
505 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
506 p4d_t *p4d = p4d_offset(pgd, addr);
507 pud_t *pud = pud_offset(p4d, addr);
508 pmd_t *pmd = pmd_offset(pud, addr);
509 struct address_space *mapping;
510 pgoff_t index;
511 static unsigned long resume;
512 static unsigned long nr_shown;
513 static unsigned long nr_unshown;
514
515 /*
516 * Allow a burst of 60 reports, then keep quiet for that minute;
517 * or allow a steady drip of one report per second.
518 */
519 if (nr_shown == 60) {
520 if (time_before(jiffies, resume)) {
521 nr_unshown++;
522 return;
523 }
524 if (nr_unshown) {
525 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
526 nr_unshown);
527 nr_unshown = 0;
528 }
529 nr_shown = 0;
530 }
531 if (nr_shown++ == 0)
532 resume = jiffies + 60 * HZ;
533
534 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
535 index = linear_page_index(vma, addr);
536
537 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
538 current->comm,
539 (long long)pte_val(pte), (long long)pmd_val(*pmd));
540 if (page)
541 dump_page(page, "bad pte");
542 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
543 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
544 pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
545 vma->vm_file,
546 vma->vm_ops ? vma->vm_ops->fault : NULL,
547 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
548 mapping ? mapping->a_ops->readpage : NULL);
549 dump_stack();
550 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
551}
552
553/*
554 * vm_normal_page -- This function gets the "struct page" associated with a pte.
555 *
556 * "Special" mappings do not wish to be associated with a "struct page" (either
557 * it doesn't exist, or it exists but they don't want to touch it). In this
558 * case, NULL is returned here. "Normal" mappings do have a struct page.
559 *
560 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
561 * pte bit, in which case this function is trivial. Secondly, an architecture
562 * may not have a spare pte bit, which requires a more complicated scheme,
563 * described below.
564 *
565 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
566 * special mapping (even if there are underlying and valid "struct pages").
567 * COWed pages of a VM_PFNMAP are always normal.
568 *
569 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
570 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
571 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
572 * mapping will always honor the rule
573 *
574 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
575 *
576 * And for normal mappings this is false.
577 *
578 * This restricts such mappings to be a linear translation from virtual address
579 * to pfn. To get around this restriction, we allow arbitrary mappings so long
580 * as the vma is not a COW mapping; in that case, we know that all ptes are
581 * special (because none can have been COWed).
582 *
583 *
584 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
585 *
586 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
587 * page" backing, however the difference is that _all_ pages with a struct
588 * page (that is, those where pfn_valid is true) are refcounted and considered
589 * normal pages by the VM. The disadvantage is that pages are refcounted
590 * (which can be slower and simply not an option for some PFNMAP users). The
591 * advantage is that we don't have to follow the strict linearity rule of
592 * PFNMAP mappings in order to support COWable mappings.
593 *
594 */
595struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
596 pte_t pte)
597{
598 unsigned long pfn = pte_pfn(pte);
599
600 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
601 if (likely(!pte_special(pte)))
602 goto check_pfn;
603 if (vma->vm_ops && vma->vm_ops->find_special_page)
604 return vma->vm_ops->find_special_page(vma, addr);
605 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
606 return NULL;
607 if (is_zero_pfn(pfn))
608 return NULL;
609 if (pte_devmap(pte))
610 return NULL;
611
612 print_bad_pte(vma, addr, pte, NULL);
613 return NULL;
614 }
615
616 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
617
618 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
619 if (vma->vm_flags & VM_MIXEDMAP) {
620 if (!pfn_valid(pfn))
621 return NULL;
622 goto out;
623 } else {
624 unsigned long off;
625 off = (addr - vma->vm_start) >> PAGE_SHIFT;
626 if (pfn == vma->vm_pgoff + off)
627 return NULL;
628 if (!is_cow_mapping(vma->vm_flags))
629 return NULL;
630 }
631 }
632
633 if (is_zero_pfn(pfn))
634 return NULL;
635
636check_pfn:
637 if (unlikely(pfn > highest_memmap_pfn)) {
638 print_bad_pte(vma, addr, pte, NULL);
639 return NULL;
640 }
641
642 /*
643 * NOTE! We still have PageReserved() pages in the page tables.
644 * eg. VDSO mappings can cause them to exist.
645 */
646out:
647 return pfn_to_page(pfn);
648}
649
650#ifdef CONFIG_TRANSPARENT_HUGEPAGE
651struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
652 pmd_t pmd)
653{
654 unsigned long pfn = pmd_pfn(pmd);
655
656 /*
657 * There is no pmd_special() but there may be special pmds, e.g.
658 * in a direct-access (dax) mapping, so let's just replicate the
659 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
660 */
661 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
662 if (vma->vm_flags & VM_MIXEDMAP) {
663 if (!pfn_valid(pfn))
664 return NULL;
665 goto out;
666 } else {
667 unsigned long off;
668 off = (addr - vma->vm_start) >> PAGE_SHIFT;
669 if (pfn == vma->vm_pgoff + off)
670 return NULL;
671 if (!is_cow_mapping(vma->vm_flags))
672 return NULL;
673 }
674 }
675
676 if (pmd_devmap(pmd))
677 return NULL;
678 if (is_huge_zero_pmd(pmd))
679 return NULL;
680 if (unlikely(pfn > highest_memmap_pfn))
681 return NULL;
682
683 /*
684 * NOTE! We still have PageReserved() pages in the page tables.
685 * eg. VDSO mappings can cause them to exist.
686 */
687out:
688 return pfn_to_page(pfn);
689}
690#endif
691
692/*
693 * copy one vm_area from one task to the other. Assumes the page tables
694 * already present in the new task to be cleared in the whole range
695 * covered by this vma.
696 */
697
698static unsigned long
699copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
700 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
701 unsigned long addr, int *rss)
702{
703 unsigned long vm_flags = vma->vm_flags;
704 pte_t pte = *src_pte;
705 struct page *page;
706 swp_entry_t entry = pte_to_swp_entry(pte);
707
708 if (likely(!non_swap_entry(entry))) {
709 if (swap_duplicate(entry) < 0)
710 return entry.val;
711
712 /* make sure dst_mm is on swapoff's mmlist. */
713 if (unlikely(list_empty(&dst_mm->mmlist))) {
714 spin_lock(&mmlist_lock);
715 if (list_empty(&dst_mm->mmlist))
716 list_add(&dst_mm->mmlist,
717 &src_mm->mmlist);
718 spin_unlock(&mmlist_lock);
719 }
720 rss[MM_SWAPENTS]++;
721 } else if (is_migration_entry(entry)) {
722 page = migration_entry_to_page(entry);
723
724 rss[mm_counter(page)]++;
725
726 if (is_write_migration_entry(entry) &&
727 is_cow_mapping(vm_flags)) {
728 /*
729 * COW mappings require pages in both
730 * parent and child to be set to read.
731 */
732 make_migration_entry_read(&entry);
733 pte = swp_entry_to_pte(entry);
734 if (pte_swp_soft_dirty(*src_pte))
735 pte = pte_swp_mksoft_dirty(pte);
736 if (pte_swp_uffd_wp(*src_pte))
737 pte = pte_swp_mkuffd_wp(pte);
738 set_pte_at(src_mm, addr, src_pte, pte);
739 }
740 } else if (is_device_private_entry(entry)) {
741 page = device_private_entry_to_page(entry);
742
743 /*
744 * Update rss count even for unaddressable pages, as
745 * they should treated just like normal pages in this
746 * respect.
747 *
748 * We will likely want to have some new rss counters
749 * for unaddressable pages, at some point. But for now
750 * keep things as they are.
751 */
752 get_page(page);
753 rss[mm_counter(page)]++;
754 page_dup_rmap(page, false);
755
756 /*
757 * We do not preserve soft-dirty information, because so
758 * far, checkpoint/restore is the only feature that
759 * requires that. And checkpoint/restore does not work
760 * when a device driver is involved (you cannot easily
761 * save and restore device driver state).
762 */
763 if (is_write_device_private_entry(entry) &&
764 is_cow_mapping(vm_flags)) {
765 make_device_private_entry_read(&entry);
766 pte = swp_entry_to_pte(entry);
767 if (pte_swp_uffd_wp(*src_pte))
768 pte = pte_swp_mkuffd_wp(pte);
769 set_pte_at(src_mm, addr, src_pte, pte);
770 }
771 }
772 set_pte_at(dst_mm, addr, dst_pte, pte);
773 return 0;
774}
775
776/*
777 * Copy a present and normal page if necessary.
778 *
779 * NOTE! The usual case is that this doesn't need to do
780 * anything, and can just return a positive value. That
781 * will let the caller know that it can just increase
782 * the page refcount and re-use the pte the traditional
783 * way.
784 *
785 * But _if_ we need to copy it because it needs to be
786 * pinned in the parent (and the child should get its own
787 * copy rather than just a reference to the same page),
788 * we'll do that here and return zero to let the caller
789 * know we're done.
790 *
791 * And if we need a pre-allocated page but don't yet have
792 * one, return a negative error to let the preallocation
793 * code know so that it can do so outside the page table
794 * lock.
795 */
796static inline int
797copy_present_page(struct mm_struct *dst_mm, struct mm_struct *src_mm,
798 pte_t *dst_pte, pte_t *src_pte,
799 struct vm_area_struct *vma, struct vm_area_struct *new,
800 unsigned long addr, int *rss, struct page **prealloc,
801 pte_t pte, struct page *page)
802{
803 struct page *new_page;
804
805 if (!is_cow_mapping(vma->vm_flags))
806 return 1;
807
808 /*
809 * What we want to do is to check whether this page may
810 * have been pinned by the parent process. If so,
811 * instead of wrprotect the pte on both sides, we copy
812 * the page immediately so that we'll always guarantee
813 * the pinned page won't be randomly replaced in the
814 * future.
815 *
816 * The page pinning checks are just "has this mm ever
817 * seen pinning", along with the (inexact) check of
818 * the page count. That might give false positives for
819 * for pinning, but it will work correctly.
820 */
821 if (likely(!atomic_read(&src_mm->has_pinned)))
822 return 1;
823 if (likely(!page_maybe_dma_pinned(page)))
824 return 1;
825
826 new_page = *prealloc;
827 if (!new_page)
828 return -EAGAIN;
829
830 /*
831 * We have a prealloc page, all good! Take it
832 * over and copy the page & arm it.
833 */
834 *prealloc = NULL;
835 copy_user_highpage(new_page, page, addr, vma);
836 __SetPageUptodate(new_page);
837 page_add_new_anon_rmap(new_page, new, addr, false);
838 lru_cache_add_inactive_or_unevictable(new_page, new);
839 rss[mm_counter(new_page)]++;
840
841 /* All done, just insert the new page copy in the child */
842 pte = mk_pte(new_page, new->vm_page_prot);
843 pte = maybe_mkwrite(pte_mkdirty(pte), new);
844 set_pte_at(dst_mm, addr, dst_pte, pte);
845 return 0;
846}
847
848/*
849 * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
850 * is required to copy this pte.
851 */
852static inline int
853copy_present_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
854 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
855 struct vm_area_struct *new,
856 unsigned long addr, int *rss, struct page **prealloc)
857{
858 unsigned long vm_flags = vma->vm_flags;
859 pte_t pte = *src_pte;
860 struct page *page;
861
862 page = vm_normal_page(vma, addr, pte);
863 if (page) {
864 int retval;
865
866 retval = copy_present_page(dst_mm, src_mm,
867 dst_pte, src_pte,
868 vma, new,
869 addr, rss, prealloc,
870 pte, page);
871 if (retval <= 0)
872 return retval;
873
874 get_page(page);
875 page_dup_rmap(page, false);
876 rss[mm_counter(page)]++;
877 }
878
879 /*
880 * If it's a COW mapping, write protect it both
881 * in the parent and the child
882 */
883 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
884 ptep_set_wrprotect(src_mm, addr, src_pte);
885 pte = pte_wrprotect(pte);
886 }
887
888 /*
889 * If it's a shared mapping, mark it clean in
890 * the child
891 */
892 if (vm_flags & VM_SHARED)
893 pte = pte_mkclean(pte);
894 pte = pte_mkold(pte);
895
896 /*
897 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
898 * does not have the VM_UFFD_WP, which means that the uffd
899 * fork event is not enabled.
900 */
901 if (!(vm_flags & VM_UFFD_WP))
902 pte = pte_clear_uffd_wp(pte);
903
904 set_pte_at(dst_mm, addr, dst_pte, pte);
905 return 0;
906}
907
908static inline struct page *
909page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
910 unsigned long addr)
911{
912 struct page *new_page;
913
914 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr);
915 if (!new_page)
916 return NULL;
917
918 if (mem_cgroup_charge(new_page, src_mm, GFP_KERNEL)) {
919 put_page(new_page);
920 return NULL;
921 }
922 cgroup_throttle_swaprate(new_page, GFP_KERNEL);
923
924 return new_page;
925}
926
927static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
928 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
929 struct vm_area_struct *new,
930 unsigned long addr, unsigned long end)
931{
932 pte_t *orig_src_pte, *orig_dst_pte;
933 pte_t *src_pte, *dst_pte;
934 spinlock_t *src_ptl, *dst_ptl;
935 int progress, ret = 0;
936 int rss[NR_MM_COUNTERS];
937 swp_entry_t entry = (swp_entry_t){0};
938 struct page *prealloc = NULL;
939
940again:
941 progress = 0;
942 init_rss_vec(rss);
943
944 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
945 if (!dst_pte) {
946 ret = -ENOMEM;
947 goto out;
948 }
949 src_pte = pte_offset_map(src_pmd, addr);
950 src_ptl = pte_lockptr(src_mm, src_pmd);
951 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
952 orig_src_pte = src_pte;
953 orig_dst_pte = dst_pte;
954 arch_enter_lazy_mmu_mode();
955
956 do {
957 /*
958 * We are holding two locks at this point - either of them
959 * could generate latencies in another task on another CPU.
960 */
961 if (progress >= 32) {
962 progress = 0;
963 if (need_resched() ||
964 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
965 break;
966 }
967 if (pte_none(*src_pte)) {
968 progress++;
969 continue;
970 }
971 if (unlikely(!pte_present(*src_pte))) {
972 entry.val = copy_nonpresent_pte(dst_mm, src_mm,
973 dst_pte, src_pte,
974 vma, addr, rss);
975 if (entry.val)
976 break;
977 progress += 8;
978 continue;
979 }
980 /* copy_present_pte() will clear `*prealloc' if consumed */
981 ret = copy_present_pte(dst_mm, src_mm, dst_pte, src_pte,
982 vma, new, addr, rss, &prealloc);
983 /*
984 * If we need a pre-allocated page for this pte, drop the
985 * locks, allocate, and try again.
986 */
987 if (unlikely(ret == -EAGAIN))
988 break;
989 if (unlikely(prealloc)) {
990 /*
991 * pre-alloc page cannot be reused by next time so as
992 * to strictly follow mempolicy (e.g., alloc_page_vma()
993 * will allocate page according to address). This
994 * could only happen if one pinned pte changed.
995 */
996 put_page(prealloc);
997 prealloc = NULL;
998 }
999 progress += 8;
1000 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1001
1002 arch_leave_lazy_mmu_mode();
1003 spin_unlock(src_ptl);
1004 pte_unmap(orig_src_pte);
1005 add_mm_rss_vec(dst_mm, rss);
1006 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1007 cond_resched();
1008
1009 if (entry.val) {
1010 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1011 ret = -ENOMEM;
1012 goto out;
1013 }
1014 entry.val = 0;
1015 } else if (ret) {
1016 WARN_ON_ONCE(ret != -EAGAIN);
1017 prealloc = page_copy_prealloc(src_mm, vma, addr);
1018 if (!prealloc)
1019 return -ENOMEM;
1020 /* We've captured and resolved the error. Reset, try again. */
1021 ret = 0;
1022 }
1023 if (addr != end)
1024 goto again;
1025out:
1026 if (unlikely(prealloc))
1027 put_page(prealloc);
1028 return ret;
1029}
1030
1031static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1032 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1033 struct vm_area_struct *new,
1034 unsigned long addr, unsigned long end)
1035{
1036 pmd_t *src_pmd, *dst_pmd;
1037 unsigned long next;
1038
1039 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1040 if (!dst_pmd)
1041 return -ENOMEM;
1042 src_pmd = pmd_offset(src_pud, addr);
1043 do {
1044 next = pmd_addr_end(addr, end);
1045 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1046 || pmd_devmap(*src_pmd)) {
1047 int err;
1048 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1049 err = copy_huge_pmd(dst_mm, src_mm,
1050 dst_pmd, src_pmd, addr, vma);
1051 if (err == -ENOMEM)
1052 return -ENOMEM;
1053 if (!err)
1054 continue;
1055 /* fall through */
1056 }
1057 if (pmd_none_or_clear_bad(src_pmd))
1058 continue;
1059 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1060 vma, new, addr, next))
1061 return -ENOMEM;
1062 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1063 return 0;
1064}
1065
1066static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1067 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1068 struct vm_area_struct *new,
1069 unsigned long addr, unsigned long end)
1070{
1071 pud_t *src_pud, *dst_pud;
1072 unsigned long next;
1073
1074 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1075 if (!dst_pud)
1076 return -ENOMEM;
1077 src_pud = pud_offset(src_p4d, addr);
1078 do {
1079 next = pud_addr_end(addr, end);
1080 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1081 int err;
1082
1083 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1084 err = copy_huge_pud(dst_mm, src_mm,
1085 dst_pud, src_pud, addr, vma);
1086 if (err == -ENOMEM)
1087 return -ENOMEM;
1088 if (!err)
1089 continue;
1090 /* fall through */
1091 }
1092 if (pud_none_or_clear_bad(src_pud))
1093 continue;
1094 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1095 vma, new, addr, next))
1096 return -ENOMEM;
1097 } while (dst_pud++, src_pud++, addr = next, addr != end);
1098 return 0;
1099}
1100
1101static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1102 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1103 struct vm_area_struct *new,
1104 unsigned long addr, unsigned long end)
1105{
1106 p4d_t *src_p4d, *dst_p4d;
1107 unsigned long next;
1108
1109 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1110 if (!dst_p4d)
1111 return -ENOMEM;
1112 src_p4d = p4d_offset(src_pgd, addr);
1113 do {
1114 next = p4d_addr_end(addr, end);
1115 if (p4d_none_or_clear_bad(src_p4d))
1116 continue;
1117 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1118 vma, new, addr, next))
1119 return -ENOMEM;
1120 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1121 return 0;
1122}
1123
1124int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1125 struct vm_area_struct *vma, struct vm_area_struct *new)
1126{
1127 pgd_t *src_pgd, *dst_pgd;
1128 unsigned long next;
1129 unsigned long addr = vma->vm_start;
1130 unsigned long end = vma->vm_end;
1131 struct mmu_notifier_range range;
1132 bool is_cow;
1133 int ret;
1134
1135 /*
1136 * Don't copy ptes where a page fault will fill them correctly.
1137 * Fork becomes much lighter when there are big shared or private
1138 * readonly mappings. The tradeoff is that copy_page_range is more
1139 * efficient than faulting.
1140 */
1141 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1142 !vma->anon_vma)
1143 return 0;
1144
1145 if (is_vm_hugetlb_page(vma))
1146 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1147
1148 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1149 /*
1150 * We do not free on error cases below as remove_vma
1151 * gets called on error from higher level routine
1152 */
1153 ret = track_pfn_copy(vma);
1154 if (ret)
1155 return ret;
1156 }
1157
1158 /*
1159 * We need to invalidate the secondary MMU mappings only when
1160 * there could be a permission downgrade on the ptes of the
1161 * parent mm. And a permission downgrade will only happen if
1162 * is_cow_mapping() returns true.
1163 */
1164 is_cow = is_cow_mapping(vma->vm_flags);
1165
1166 if (is_cow) {
1167 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1168 0, vma, src_mm, addr, end);
1169 mmu_notifier_invalidate_range_start(&range);
1170 }
1171
1172 ret = 0;
1173 dst_pgd = pgd_offset(dst_mm, addr);
1174 src_pgd = pgd_offset(src_mm, addr);
1175 do {
1176 next = pgd_addr_end(addr, end);
1177 if (pgd_none_or_clear_bad(src_pgd))
1178 continue;
1179 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1180 vma, new, addr, next))) {
1181 ret = -ENOMEM;
1182 break;
1183 }
1184 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1185
1186 if (is_cow)
1187 mmu_notifier_invalidate_range_end(&range);
1188 return ret;
1189}
1190
1191static unsigned long zap_pte_range(struct mmu_gather *tlb,
1192 struct vm_area_struct *vma, pmd_t *pmd,
1193 unsigned long addr, unsigned long end,
1194 struct zap_details *details)
1195{
1196 struct mm_struct *mm = tlb->mm;
1197 int force_flush = 0;
1198 int rss[NR_MM_COUNTERS];
1199 spinlock_t *ptl;
1200 pte_t *start_pte;
1201 pte_t *pte;
1202 swp_entry_t entry;
1203
1204 tlb_change_page_size(tlb, PAGE_SIZE);
1205again:
1206 init_rss_vec(rss);
1207 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1208 pte = start_pte;
1209 flush_tlb_batched_pending(mm);
1210 arch_enter_lazy_mmu_mode();
1211 do {
1212 pte_t ptent = *pte;
1213 if (pte_none(ptent))
1214 continue;
1215
1216 if (need_resched())
1217 break;
1218
1219 if (pte_present(ptent)) {
1220 struct page *page;
1221
1222 page = vm_normal_page(vma, addr, ptent);
1223 if (unlikely(details) && page) {
1224 /*
1225 * unmap_shared_mapping_pages() wants to
1226 * invalidate cache without truncating:
1227 * unmap shared but keep private pages.
1228 */
1229 if (details->check_mapping &&
1230 details->check_mapping != page_rmapping(page))
1231 continue;
1232 }
1233 ptent = ptep_get_and_clear_full(mm, addr, pte,
1234 tlb->fullmm);
1235 tlb_remove_tlb_entry(tlb, pte, addr);
1236 if (unlikely(!page))
1237 continue;
1238
1239 if (!PageAnon(page)) {
1240 if (pte_dirty(ptent)) {
1241 force_flush = 1;
1242 set_page_dirty(page);
1243 }
1244 if (pte_young(ptent) &&
1245 likely(!(vma->vm_flags & VM_SEQ_READ)))
1246 mark_page_accessed(page);
1247 }
1248 rss[mm_counter(page)]--;
1249 page_remove_rmap(page, false);
1250 if (unlikely(page_mapcount(page) < 0))
1251 print_bad_pte(vma, addr, ptent, page);
1252 if (unlikely(__tlb_remove_page(tlb, page))) {
1253 force_flush = 1;
1254 addr += PAGE_SIZE;
1255 break;
1256 }
1257 continue;
1258 }
1259
1260 entry = pte_to_swp_entry(ptent);
1261 if (is_device_private_entry(entry)) {
1262 struct page *page = device_private_entry_to_page(entry);
1263
1264 if (unlikely(details && details->check_mapping)) {
1265 /*
1266 * unmap_shared_mapping_pages() wants to
1267 * invalidate cache without truncating:
1268 * unmap shared but keep private pages.
1269 */
1270 if (details->check_mapping !=
1271 page_rmapping(page))
1272 continue;
1273 }
1274
1275 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1276 rss[mm_counter(page)]--;
1277 page_remove_rmap(page, false);
1278 put_page(page);
1279 continue;
1280 }
1281
1282 /* If details->check_mapping, we leave swap entries. */
1283 if (unlikely(details))
1284 continue;
1285
1286 if (!non_swap_entry(entry))
1287 rss[MM_SWAPENTS]--;
1288 else if (is_migration_entry(entry)) {
1289 struct page *page;
1290
1291 page = migration_entry_to_page(entry);
1292 rss[mm_counter(page)]--;
1293 }
1294 if (unlikely(!free_swap_and_cache(entry)))
1295 print_bad_pte(vma, addr, ptent, NULL);
1296 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1297 } while (pte++, addr += PAGE_SIZE, addr != end);
1298
1299 add_mm_rss_vec(mm, rss);
1300 arch_leave_lazy_mmu_mode();
1301
1302 /* Do the actual TLB flush before dropping ptl */
1303 if (force_flush)
1304 tlb_flush_mmu_tlbonly(tlb);
1305 pte_unmap_unlock(start_pte, ptl);
1306
1307 /*
1308 * If we forced a TLB flush (either due to running out of
1309 * batch buffers or because we needed to flush dirty TLB
1310 * entries before releasing the ptl), free the batched
1311 * memory too. Restart if we didn't do everything.
1312 */
1313 if (force_flush) {
1314 force_flush = 0;
1315 tlb_flush_mmu(tlb);
1316 }
1317
1318 if (addr != end) {
1319 cond_resched();
1320 goto again;
1321 }
1322
1323 return addr;
1324}
1325
1326static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1327 struct vm_area_struct *vma, pud_t *pud,
1328 unsigned long addr, unsigned long end,
1329 struct zap_details *details)
1330{
1331 pmd_t *pmd;
1332 unsigned long next;
1333
1334 pmd = pmd_offset(pud, addr);
1335 do {
1336 next = pmd_addr_end(addr, end);
1337 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1338 if (next - addr != HPAGE_PMD_SIZE)
1339 __split_huge_pmd(vma, pmd, addr, false, NULL);
1340 else if (zap_huge_pmd(tlb, vma, pmd, addr))
1341 goto next;
1342 /* fall through */
1343 }
1344 /*
1345 * Here there can be other concurrent MADV_DONTNEED or
1346 * trans huge page faults running, and if the pmd is
1347 * none or trans huge it can change under us. This is
1348 * because MADV_DONTNEED holds the mmap_lock in read
1349 * mode.
1350 */
1351 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1352 goto next;
1353 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1354next:
1355 cond_resched();
1356 } while (pmd++, addr = next, addr != end);
1357
1358 return addr;
1359}
1360
1361static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1362 struct vm_area_struct *vma, p4d_t *p4d,
1363 unsigned long addr, unsigned long end,
1364 struct zap_details *details)
1365{
1366 pud_t *pud;
1367 unsigned long next;
1368
1369 pud = pud_offset(p4d, addr);
1370 do {
1371 next = pud_addr_end(addr, end);
1372 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1373 if (next - addr != HPAGE_PUD_SIZE) {
1374 mmap_assert_locked(tlb->mm);
1375 split_huge_pud(vma, pud, addr);
1376 } else if (zap_huge_pud(tlb, vma, pud, addr))
1377 goto next;
1378 /* fall through */
1379 }
1380 if (pud_none_or_clear_bad(pud))
1381 continue;
1382 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1383next:
1384 cond_resched();
1385 } while (pud++, addr = next, addr != end);
1386
1387 return addr;
1388}
1389
1390static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1391 struct vm_area_struct *vma, pgd_t *pgd,
1392 unsigned long addr, unsigned long end,
1393 struct zap_details *details)
1394{
1395 p4d_t *p4d;
1396 unsigned long next;
1397
1398 p4d = p4d_offset(pgd, addr);
1399 do {
1400 next = p4d_addr_end(addr, end);
1401 if (p4d_none_or_clear_bad(p4d))
1402 continue;
1403 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1404 } while (p4d++, addr = next, addr != end);
1405
1406 return addr;
1407}
1408
1409void unmap_page_range(struct mmu_gather *tlb,
1410 struct vm_area_struct *vma,
1411 unsigned long addr, unsigned long end,
1412 struct zap_details *details)
1413{
1414 pgd_t *pgd;
1415 unsigned long next;
1416
1417 BUG_ON(addr >= end);
1418 tlb_start_vma(tlb, vma);
1419 pgd = pgd_offset(vma->vm_mm, addr);
1420 do {
1421 next = pgd_addr_end(addr, end);
1422 if (pgd_none_or_clear_bad(pgd))
1423 continue;
1424 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1425 } while (pgd++, addr = next, addr != end);
1426 tlb_end_vma(tlb, vma);
1427}
1428
1429
1430static void unmap_single_vma(struct mmu_gather *tlb,
1431 struct vm_area_struct *vma, unsigned long start_addr,
1432 unsigned long end_addr,
1433 struct zap_details *details)
1434{
1435 unsigned long start = max(vma->vm_start, start_addr);
1436 unsigned long end;
1437
1438 if (start >= vma->vm_end)
1439 return;
1440 end = min(vma->vm_end, end_addr);
1441 if (end <= vma->vm_start)
1442 return;
1443
1444 if (vma->vm_file)
1445 uprobe_munmap(vma, start, end);
1446
1447 if (unlikely(vma->vm_flags & VM_PFNMAP))
1448 untrack_pfn(vma, 0, 0);
1449
1450 if (start != end) {
1451 if (unlikely(is_vm_hugetlb_page(vma))) {
1452 /*
1453 * It is undesirable to test vma->vm_file as it
1454 * should be non-null for valid hugetlb area.
1455 * However, vm_file will be NULL in the error
1456 * cleanup path of mmap_region. When
1457 * hugetlbfs ->mmap method fails,
1458 * mmap_region() nullifies vma->vm_file
1459 * before calling this function to clean up.
1460 * Since no pte has actually been setup, it is
1461 * safe to do nothing in this case.
1462 */
1463 if (vma->vm_file) {
1464 i_mmap_lock_write(vma->vm_file->f_mapping);
1465 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1466 i_mmap_unlock_write(vma->vm_file->f_mapping);
1467 }
1468 } else
1469 unmap_page_range(tlb, vma, start, end, details);
1470 }
1471}
1472
1473/**
1474 * unmap_vmas - unmap a range of memory covered by a list of vma's
1475 * @tlb: address of the caller's struct mmu_gather
1476 * @vma: the starting vma
1477 * @start_addr: virtual address at which to start unmapping
1478 * @end_addr: virtual address at which to end unmapping
1479 *
1480 * Unmap all pages in the vma list.
1481 *
1482 * Only addresses between `start' and `end' will be unmapped.
1483 *
1484 * The VMA list must be sorted in ascending virtual address order.
1485 *
1486 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1487 * range after unmap_vmas() returns. So the only responsibility here is to
1488 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1489 * drops the lock and schedules.
1490 */
1491void unmap_vmas(struct mmu_gather *tlb,
1492 struct vm_area_struct *vma, unsigned long start_addr,
1493 unsigned long end_addr)
1494{
1495 struct mmu_notifier_range range;
1496
1497 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1498 start_addr, end_addr);
1499 mmu_notifier_invalidate_range_start(&range);
1500 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1501 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1502 mmu_notifier_invalidate_range_end(&range);
1503}
1504
1505/**
1506 * zap_page_range - remove user pages in a given range
1507 * @vma: vm_area_struct holding the applicable pages
1508 * @start: starting address of pages to zap
1509 * @size: number of bytes to zap
1510 *
1511 * Caller must protect the VMA list
1512 */
1513void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1514 unsigned long size)
1515{
1516 struct mmu_notifier_range range;
1517 struct mmu_gather tlb;
1518
1519 lru_add_drain();
1520 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1521 start, start + size);
1522 tlb_gather_mmu(&tlb, vma->vm_mm, start, range.end);
1523 update_hiwater_rss(vma->vm_mm);
1524 mmu_notifier_invalidate_range_start(&range);
1525 for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
1526 unmap_single_vma(&tlb, vma, start, range.end, NULL);
1527 mmu_notifier_invalidate_range_end(&range);
1528 tlb_finish_mmu(&tlb, start, range.end);
1529}
1530
1531/**
1532 * zap_page_range_single - remove user pages in a given range
1533 * @vma: vm_area_struct holding the applicable pages
1534 * @address: starting address of pages to zap
1535 * @size: number of bytes to zap
1536 * @details: details of shared cache invalidation
1537 *
1538 * The range must fit into one VMA.
1539 */
1540static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1541 unsigned long size, struct zap_details *details)
1542{
1543 struct mmu_notifier_range range;
1544 struct mmu_gather tlb;
1545
1546 lru_add_drain();
1547 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1548 address, address + size);
1549 tlb_gather_mmu(&tlb, vma->vm_mm, address, range.end);
1550 update_hiwater_rss(vma->vm_mm);
1551 mmu_notifier_invalidate_range_start(&range);
1552 unmap_single_vma(&tlb, vma, address, range.end, details);
1553 mmu_notifier_invalidate_range_end(&range);
1554 tlb_finish_mmu(&tlb, address, range.end);
1555}
1556
1557/**
1558 * zap_vma_ptes - remove ptes mapping the vma
1559 * @vma: vm_area_struct holding ptes to be zapped
1560 * @address: starting address of pages to zap
1561 * @size: number of bytes to zap
1562 *
1563 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1564 *
1565 * The entire address range must be fully contained within the vma.
1566 *
1567 */
1568void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1569 unsigned long size)
1570{
1571 if (address < vma->vm_start || address + size > vma->vm_end ||
1572 !(vma->vm_flags & VM_PFNMAP))
1573 return;
1574
1575 zap_page_range_single(vma, address, size, NULL);
1576}
1577EXPORT_SYMBOL_GPL(zap_vma_ptes);
1578
1579static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1580{
1581 pgd_t *pgd;
1582 p4d_t *p4d;
1583 pud_t *pud;
1584 pmd_t *pmd;
1585
1586 pgd = pgd_offset(mm, addr);
1587 p4d = p4d_alloc(mm, pgd, addr);
1588 if (!p4d)
1589 return NULL;
1590 pud = pud_alloc(mm, p4d, addr);
1591 if (!pud)
1592 return NULL;
1593 pmd = pmd_alloc(mm, pud, addr);
1594 if (!pmd)
1595 return NULL;
1596
1597 VM_BUG_ON(pmd_trans_huge(*pmd));
1598 return pmd;
1599}
1600
1601pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1602 spinlock_t **ptl)
1603{
1604 pmd_t *pmd = walk_to_pmd(mm, addr);
1605
1606 if (!pmd)
1607 return NULL;
1608 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1609}
1610
1611static int validate_page_before_insert(struct page *page)
1612{
1613 if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1614 return -EINVAL;
1615 flush_dcache_page(page);
1616 return 0;
1617}
1618
1619static int insert_page_into_pte_locked(struct mm_struct *mm, pte_t *pte,
1620 unsigned long addr, struct page *page, pgprot_t prot)
1621{
1622 if (!pte_none(*pte))
1623 return -EBUSY;
1624 /* Ok, finally just insert the thing.. */
1625 get_page(page);
1626 inc_mm_counter_fast(mm, mm_counter_file(page));
1627 page_add_file_rmap(page, false);
1628 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1629 return 0;
1630}
1631
1632/*
1633 * This is the old fallback for page remapping.
1634 *
1635 * For historical reasons, it only allows reserved pages. Only
1636 * old drivers should use this, and they needed to mark their
1637 * pages reserved for the old functions anyway.
1638 */
1639static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1640 struct page *page, pgprot_t prot)
1641{
1642 struct mm_struct *mm = vma->vm_mm;
1643 int retval;
1644 pte_t *pte;
1645 spinlock_t *ptl;
1646
1647 retval = validate_page_before_insert(page);
1648 if (retval)
1649 goto out;
1650 retval = -ENOMEM;
1651 pte = get_locked_pte(mm, addr, &ptl);
1652 if (!pte)
1653 goto out;
1654 retval = insert_page_into_pte_locked(mm, pte, addr, page, prot);
1655 pte_unmap_unlock(pte, ptl);
1656out:
1657 return retval;
1658}
1659
1660#ifdef pte_index
1661static int insert_page_in_batch_locked(struct mm_struct *mm, pte_t *pte,
1662 unsigned long addr, struct page *page, pgprot_t prot)
1663{
1664 int err;
1665
1666 if (!page_count(page))
1667 return -EINVAL;
1668 err = validate_page_before_insert(page);
1669 if (err)
1670 return err;
1671 return insert_page_into_pte_locked(mm, pte, addr, page, prot);
1672}
1673
1674/* insert_pages() amortizes the cost of spinlock operations
1675 * when inserting pages in a loop. Arch *must* define pte_index.
1676 */
1677static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
1678 struct page **pages, unsigned long *num, pgprot_t prot)
1679{
1680 pmd_t *pmd = NULL;
1681 pte_t *start_pte, *pte;
1682 spinlock_t *pte_lock;
1683 struct mm_struct *const mm = vma->vm_mm;
1684 unsigned long curr_page_idx = 0;
1685 unsigned long remaining_pages_total = *num;
1686 unsigned long pages_to_write_in_pmd;
1687 int ret;
1688more:
1689 ret = -EFAULT;
1690 pmd = walk_to_pmd(mm, addr);
1691 if (!pmd)
1692 goto out;
1693
1694 pages_to_write_in_pmd = min_t(unsigned long,
1695 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
1696
1697 /* Allocate the PTE if necessary; takes PMD lock once only. */
1698 ret = -ENOMEM;
1699 if (pte_alloc(mm, pmd))
1700 goto out;
1701
1702 while (pages_to_write_in_pmd) {
1703 int pte_idx = 0;
1704 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
1705
1706 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
1707 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
1708 int err = insert_page_in_batch_locked(mm, pte,
1709 addr, pages[curr_page_idx], prot);
1710 if (unlikely(err)) {
1711 pte_unmap_unlock(start_pte, pte_lock);
1712 ret = err;
1713 remaining_pages_total -= pte_idx;
1714 goto out;
1715 }
1716 addr += PAGE_SIZE;
1717 ++curr_page_idx;
1718 }
1719 pte_unmap_unlock(start_pte, pte_lock);
1720 pages_to_write_in_pmd -= batch_size;
1721 remaining_pages_total -= batch_size;
1722 }
1723 if (remaining_pages_total)
1724 goto more;
1725 ret = 0;
1726out:
1727 *num = remaining_pages_total;
1728 return ret;
1729}
1730#endif /* ifdef pte_index */
1731
1732/**
1733 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
1734 * @vma: user vma to map to
1735 * @addr: target start user address of these pages
1736 * @pages: source kernel pages
1737 * @num: in: number of pages to map. out: number of pages that were *not*
1738 * mapped. (0 means all pages were successfully mapped).
1739 *
1740 * Preferred over vm_insert_page() when inserting multiple pages.
1741 *
1742 * In case of error, we may have mapped a subset of the provided
1743 * pages. It is the caller's responsibility to account for this case.
1744 *
1745 * The same restrictions apply as in vm_insert_page().
1746 */
1747int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
1748 struct page **pages, unsigned long *num)
1749{
1750#ifdef pte_index
1751 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
1752
1753 if (addr < vma->vm_start || end_addr >= vma->vm_end)
1754 return -EFAULT;
1755 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1756 BUG_ON(mmap_read_trylock(vma->vm_mm));
1757 BUG_ON(vma->vm_flags & VM_PFNMAP);
1758 vma->vm_flags |= VM_MIXEDMAP;
1759 }
1760 /* Defer page refcount checking till we're about to map that page. */
1761 return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
1762#else
1763 unsigned long idx = 0, pgcount = *num;
1764 int err = -EINVAL;
1765
1766 for (; idx < pgcount; ++idx) {
1767 err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
1768 if (err)
1769 break;
1770 }
1771 *num = pgcount - idx;
1772 return err;
1773#endif /* ifdef pte_index */
1774}
1775EXPORT_SYMBOL(vm_insert_pages);
1776
1777/**
1778 * vm_insert_page - insert single page into user vma
1779 * @vma: user vma to map to
1780 * @addr: target user address of this page
1781 * @page: source kernel page
1782 *
1783 * This allows drivers to insert individual pages they've allocated
1784 * into a user vma.
1785 *
1786 * The page has to be a nice clean _individual_ kernel allocation.
1787 * If you allocate a compound page, you need to have marked it as
1788 * such (__GFP_COMP), or manually just split the page up yourself
1789 * (see split_page()).
1790 *
1791 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1792 * took an arbitrary page protection parameter. This doesn't allow
1793 * that. Your vma protection will have to be set up correctly, which
1794 * means that if you want a shared writable mapping, you'd better
1795 * ask for a shared writable mapping!
1796 *
1797 * The page does not need to be reserved.
1798 *
1799 * Usually this function is called from f_op->mmap() handler
1800 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
1801 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1802 * function from other places, for example from page-fault handler.
1803 *
1804 * Return: %0 on success, negative error code otherwise.
1805 */
1806int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1807 struct page *page)
1808{
1809 if (addr < vma->vm_start || addr >= vma->vm_end)
1810 return -EFAULT;
1811 if (!page_count(page))
1812 return -EINVAL;
1813 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1814 BUG_ON(mmap_read_trylock(vma->vm_mm));
1815 BUG_ON(vma->vm_flags & VM_PFNMAP);
1816 vma->vm_flags |= VM_MIXEDMAP;
1817 }
1818 return insert_page(vma, addr, page, vma->vm_page_prot);
1819}
1820EXPORT_SYMBOL(vm_insert_page);
1821
1822/*
1823 * __vm_map_pages - maps range of kernel pages into user vma
1824 * @vma: user vma to map to
1825 * @pages: pointer to array of source kernel pages
1826 * @num: number of pages in page array
1827 * @offset: user's requested vm_pgoff
1828 *
1829 * This allows drivers to map range of kernel pages into a user vma.
1830 *
1831 * Return: 0 on success and error code otherwise.
1832 */
1833static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1834 unsigned long num, unsigned long offset)
1835{
1836 unsigned long count = vma_pages(vma);
1837 unsigned long uaddr = vma->vm_start;
1838 int ret, i;
1839
1840 /* Fail if the user requested offset is beyond the end of the object */
1841 if (offset >= num)
1842 return -ENXIO;
1843
1844 /* Fail if the user requested size exceeds available object size */
1845 if (count > num - offset)
1846 return -ENXIO;
1847
1848 for (i = 0; i < count; i++) {
1849 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
1850 if (ret < 0)
1851 return ret;
1852 uaddr += PAGE_SIZE;
1853 }
1854
1855 return 0;
1856}
1857
1858/**
1859 * vm_map_pages - maps range of kernel pages starts with non zero offset
1860 * @vma: user vma to map to
1861 * @pages: pointer to array of source kernel pages
1862 * @num: number of pages in page array
1863 *
1864 * Maps an object consisting of @num pages, catering for the user's
1865 * requested vm_pgoff
1866 *
1867 * If we fail to insert any page into the vma, the function will return
1868 * immediately leaving any previously inserted pages present. Callers
1869 * from the mmap handler may immediately return the error as their caller
1870 * will destroy the vma, removing any successfully inserted pages. Other
1871 * callers should make their own arrangements for calling unmap_region().
1872 *
1873 * Context: Process context. Called by mmap handlers.
1874 * Return: 0 on success and error code otherwise.
1875 */
1876int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1877 unsigned long num)
1878{
1879 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
1880}
1881EXPORT_SYMBOL(vm_map_pages);
1882
1883/**
1884 * vm_map_pages_zero - map range of kernel pages starts with zero offset
1885 * @vma: user vma to map to
1886 * @pages: pointer to array of source kernel pages
1887 * @num: number of pages in page array
1888 *
1889 * Similar to vm_map_pages(), except that it explicitly sets the offset
1890 * to 0. This function is intended for the drivers that did not consider
1891 * vm_pgoff.
1892 *
1893 * Context: Process context. Called by mmap handlers.
1894 * Return: 0 on success and error code otherwise.
1895 */
1896int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
1897 unsigned long num)
1898{
1899 return __vm_map_pages(vma, pages, num, 0);
1900}
1901EXPORT_SYMBOL(vm_map_pages_zero);
1902
1903static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1904 pfn_t pfn, pgprot_t prot, bool mkwrite)
1905{
1906 struct mm_struct *mm = vma->vm_mm;
1907 pte_t *pte, entry;
1908 spinlock_t *ptl;
1909
1910 pte = get_locked_pte(mm, addr, &ptl);
1911 if (!pte)
1912 return VM_FAULT_OOM;
1913 if (!pte_none(*pte)) {
1914 if (mkwrite) {
1915 /*
1916 * For read faults on private mappings the PFN passed
1917 * in may not match the PFN we have mapped if the
1918 * mapped PFN is a writeable COW page. In the mkwrite
1919 * case we are creating a writable PTE for a shared
1920 * mapping and we expect the PFNs to match. If they
1921 * don't match, we are likely racing with block
1922 * allocation and mapping invalidation so just skip the
1923 * update.
1924 */
1925 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
1926 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
1927 goto out_unlock;
1928 }
1929 entry = pte_mkyoung(*pte);
1930 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1931 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
1932 update_mmu_cache(vma, addr, pte);
1933 }
1934 goto out_unlock;
1935 }
1936
1937 /* Ok, finally just insert the thing.. */
1938 if (pfn_t_devmap(pfn))
1939 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1940 else
1941 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1942
1943 if (mkwrite) {
1944 entry = pte_mkyoung(entry);
1945 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1946 }
1947
1948 set_pte_at(mm, addr, pte, entry);
1949 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1950
1951out_unlock:
1952 pte_unmap_unlock(pte, ptl);
1953 return VM_FAULT_NOPAGE;
1954}
1955
1956/**
1957 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1958 * @vma: user vma to map to
1959 * @addr: target user address of this page
1960 * @pfn: source kernel pfn
1961 * @pgprot: pgprot flags for the inserted page
1962 *
1963 * This is exactly like vmf_insert_pfn(), except that it allows drivers
1964 * to override pgprot on a per-page basis.
1965 *
1966 * This only makes sense for IO mappings, and it makes no sense for
1967 * COW mappings. In general, using multiple vmas is preferable;
1968 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
1969 * impractical.
1970 *
1971 * See vmf_insert_mixed_prot() for a discussion of the implication of using
1972 * a value of @pgprot different from that of @vma->vm_page_prot.
1973 *
1974 * Context: Process context. May allocate using %GFP_KERNEL.
1975 * Return: vm_fault_t value.
1976 */
1977vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1978 unsigned long pfn, pgprot_t pgprot)
1979{
1980 /*
1981 * Technically, architectures with pte_special can avoid all these
1982 * restrictions (same for remap_pfn_range). However we would like
1983 * consistency in testing and feature parity among all, so we should
1984 * try to keep these invariants in place for everybody.
1985 */
1986 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1987 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1988 (VM_PFNMAP|VM_MIXEDMAP));
1989 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1990 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1991
1992 if (addr < vma->vm_start || addr >= vma->vm_end)
1993 return VM_FAULT_SIGBUS;
1994
1995 if (!pfn_modify_allowed(pfn, pgprot))
1996 return VM_FAULT_SIGBUS;
1997
1998 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1999
2000 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2001 false);
2002}
2003EXPORT_SYMBOL(vmf_insert_pfn_prot);
2004
2005/**
2006 * vmf_insert_pfn - insert single pfn into user vma
2007 * @vma: user vma to map to
2008 * @addr: target user address of this page
2009 * @pfn: source kernel pfn
2010 *
2011 * Similar to vm_insert_page, this allows drivers to insert individual pages
2012 * they've allocated into a user vma. Same comments apply.
2013 *
2014 * This function should only be called from a vm_ops->fault handler, and
2015 * in that case the handler should return the result of this function.
2016 *
2017 * vma cannot be a COW mapping.
2018 *
2019 * As this is called only for pages that do not currently exist, we
2020 * do not need to flush old virtual caches or the TLB.
2021 *
2022 * Context: Process context. May allocate using %GFP_KERNEL.
2023 * Return: vm_fault_t value.
2024 */
2025vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2026 unsigned long pfn)
2027{
2028 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2029}
2030EXPORT_SYMBOL(vmf_insert_pfn);
2031
2032static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
2033{
2034 /* these checks mirror the abort conditions in vm_normal_page */
2035 if (vma->vm_flags & VM_MIXEDMAP)
2036 return true;
2037 if (pfn_t_devmap(pfn))
2038 return true;
2039 if (pfn_t_special(pfn))
2040 return true;
2041 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2042 return true;
2043 return false;
2044}
2045
2046static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2047 unsigned long addr, pfn_t pfn, pgprot_t pgprot,
2048 bool mkwrite)
2049{
2050 int err;
2051
2052 BUG_ON(!vm_mixed_ok(vma, pfn));
2053
2054 if (addr < vma->vm_start || addr >= vma->vm_end)
2055 return VM_FAULT_SIGBUS;
2056
2057 track_pfn_insert(vma, &pgprot, pfn);
2058
2059 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2060 return VM_FAULT_SIGBUS;
2061
2062 /*
2063 * If we don't have pte special, then we have to use the pfn_valid()
2064 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2065 * refcount the page if pfn_valid is true (hence insert_page rather
2066 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2067 * without pte special, it would there be refcounted as a normal page.
2068 */
2069 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2070 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2071 struct page *page;
2072
2073 /*
2074 * At this point we are committed to insert_page()
2075 * regardless of whether the caller specified flags that
2076 * result in pfn_t_has_page() == false.
2077 */
2078 page = pfn_to_page(pfn_t_to_pfn(pfn));
2079 err = insert_page(vma, addr, page, pgprot);
2080 } else {
2081 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2082 }
2083
2084 if (err == -ENOMEM)
2085 return VM_FAULT_OOM;
2086 if (err < 0 && err != -EBUSY)
2087 return VM_FAULT_SIGBUS;
2088
2089 return VM_FAULT_NOPAGE;
2090}
2091
2092/**
2093 * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
2094 * @vma: user vma to map to
2095 * @addr: target user address of this page
2096 * @pfn: source kernel pfn
2097 * @pgprot: pgprot flags for the inserted page
2098 *
2099 * This is exactly like vmf_insert_mixed(), except that it allows drivers
2100 * to override pgprot on a per-page basis.
2101 *
2102 * Typically this function should be used by drivers to set caching- and
2103 * encryption bits different than those of @vma->vm_page_prot, because
2104 * the caching- or encryption mode may not be known at mmap() time.
2105 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2106 * to set caching and encryption bits for those vmas (except for COW pages).
2107 * This is ensured by core vm only modifying these page table entries using
2108 * functions that don't touch caching- or encryption bits, using pte_modify()
2109 * if needed. (See for example mprotect()).
2110 * Also when new page-table entries are created, this is only done using the
2111 * fault() callback, and never using the value of vma->vm_page_prot,
2112 * except for page-table entries that point to anonymous pages as the result
2113 * of COW.
2114 *
2115 * Context: Process context. May allocate using %GFP_KERNEL.
2116 * Return: vm_fault_t value.
2117 */
2118vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
2119 pfn_t pfn, pgprot_t pgprot)
2120{
2121 return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
2122}
2123EXPORT_SYMBOL(vmf_insert_mixed_prot);
2124
2125vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2126 pfn_t pfn)
2127{
2128 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
2129}
2130EXPORT_SYMBOL(vmf_insert_mixed);
2131
2132/*
2133 * If the insertion of PTE failed because someone else already added a
2134 * different entry in the mean time, we treat that as success as we assume
2135 * the same entry was actually inserted.
2136 */
2137vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2138 unsigned long addr, pfn_t pfn)
2139{
2140 return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
2141}
2142EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
2143
2144/*
2145 * maps a range of physical memory into the requested pages. the old
2146 * mappings are removed. any references to nonexistent pages results
2147 * in null mappings (currently treated as "copy-on-access")
2148 */
2149static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2150 unsigned long addr, unsigned long end,
2151 unsigned long pfn, pgprot_t prot)
2152{
2153 pte_t *pte;
2154 spinlock_t *ptl;
2155 int err = 0;
2156
2157 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2158 if (!pte)
2159 return -ENOMEM;
2160 arch_enter_lazy_mmu_mode();
2161 do {
2162 BUG_ON(!pte_none(*pte));
2163 if (!pfn_modify_allowed(pfn, prot)) {
2164 err = -EACCES;
2165 break;
2166 }
2167 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2168 pfn++;
2169 } while (pte++, addr += PAGE_SIZE, addr != end);
2170 arch_leave_lazy_mmu_mode();
2171 pte_unmap_unlock(pte - 1, ptl);
2172 return err;
2173}
2174
2175static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2176 unsigned long addr, unsigned long end,
2177 unsigned long pfn, pgprot_t prot)
2178{
2179 pmd_t *pmd;
2180 unsigned long next;
2181 int err;
2182
2183 pfn -= addr >> PAGE_SHIFT;
2184 pmd = pmd_alloc(mm, pud, addr);
2185 if (!pmd)
2186 return -ENOMEM;
2187 VM_BUG_ON(pmd_trans_huge(*pmd));
2188 do {
2189 next = pmd_addr_end(addr, end);
2190 err = remap_pte_range(mm, pmd, addr, next,
2191 pfn + (addr >> PAGE_SHIFT), prot);
2192 if (err)
2193 return err;
2194 } while (pmd++, addr = next, addr != end);
2195 return 0;
2196}
2197
2198static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2199 unsigned long addr, unsigned long end,
2200 unsigned long pfn, pgprot_t prot)
2201{
2202 pud_t *pud;
2203 unsigned long next;
2204 int err;
2205
2206 pfn -= addr >> PAGE_SHIFT;
2207 pud = pud_alloc(mm, p4d, addr);
2208 if (!pud)
2209 return -ENOMEM;
2210 do {
2211 next = pud_addr_end(addr, end);
2212 err = remap_pmd_range(mm, pud, addr, next,
2213 pfn + (addr >> PAGE_SHIFT), prot);
2214 if (err)
2215 return err;
2216 } while (pud++, addr = next, addr != end);
2217 return 0;
2218}
2219
2220static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2221 unsigned long addr, unsigned long end,
2222 unsigned long pfn, pgprot_t prot)
2223{
2224 p4d_t *p4d;
2225 unsigned long next;
2226 int err;
2227
2228 pfn -= addr >> PAGE_SHIFT;
2229 p4d = p4d_alloc(mm, pgd, addr);
2230 if (!p4d)
2231 return -ENOMEM;
2232 do {
2233 next = p4d_addr_end(addr, end);
2234 err = remap_pud_range(mm, p4d, addr, next,
2235 pfn + (addr >> PAGE_SHIFT), prot);
2236 if (err)
2237 return err;
2238 } while (p4d++, addr = next, addr != end);
2239 return 0;
2240}
2241
2242/**
2243 * remap_pfn_range - remap kernel memory to userspace
2244 * @vma: user vma to map to
2245 * @addr: target page aligned user address to start at
2246 * @pfn: page frame number of kernel physical memory address
2247 * @size: size of mapping area
2248 * @prot: page protection flags for this mapping
2249 *
2250 * Note: this is only safe if the mm semaphore is held when called.
2251 *
2252 * Return: %0 on success, negative error code otherwise.
2253 */
2254int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2255 unsigned long pfn, unsigned long size, pgprot_t prot)
2256{
2257 pgd_t *pgd;
2258 unsigned long next;
2259 unsigned long end = addr + PAGE_ALIGN(size);
2260 struct mm_struct *mm = vma->vm_mm;
2261 unsigned long remap_pfn = pfn;
2262 int err;
2263
2264 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2265 return -EINVAL;
2266
2267 /*
2268 * Physically remapped pages are special. Tell the
2269 * rest of the world about it:
2270 * VM_IO tells people not to look at these pages
2271 * (accesses can have side effects).
2272 * VM_PFNMAP tells the core MM that the base pages are just
2273 * raw PFN mappings, and do not have a "struct page" associated
2274 * with them.
2275 * VM_DONTEXPAND
2276 * Disable vma merging and expanding with mremap().
2277 * VM_DONTDUMP
2278 * Omit vma from core dump, even when VM_IO turned off.
2279 *
2280 * There's a horrible special case to handle copy-on-write
2281 * behaviour that some programs depend on. We mark the "original"
2282 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2283 * See vm_normal_page() for details.
2284 */
2285 if (is_cow_mapping(vma->vm_flags)) {
2286 if (addr != vma->vm_start || end != vma->vm_end)
2287 return -EINVAL;
2288 vma->vm_pgoff = pfn;
2289 }
2290
2291 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
2292 if (err)
2293 return -EINVAL;
2294
2295 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2296
2297 BUG_ON(addr >= end);
2298 pfn -= addr >> PAGE_SHIFT;
2299 pgd = pgd_offset(mm, addr);
2300 flush_cache_range(vma, addr, end);
2301 do {
2302 next = pgd_addr_end(addr, end);
2303 err = remap_p4d_range(mm, pgd, addr, next,
2304 pfn + (addr >> PAGE_SHIFT), prot);
2305 if (err)
2306 break;
2307 } while (pgd++, addr = next, addr != end);
2308
2309 if (err)
2310 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
2311
2312 return err;
2313}
2314EXPORT_SYMBOL(remap_pfn_range);
2315
2316/**
2317 * vm_iomap_memory - remap memory to userspace
2318 * @vma: user vma to map to
2319 * @start: start of the physical memory to be mapped
2320 * @len: size of area
2321 *
2322 * This is a simplified io_remap_pfn_range() for common driver use. The
2323 * driver just needs to give us the physical memory range to be mapped,
2324 * we'll figure out the rest from the vma information.
2325 *
2326 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2327 * whatever write-combining details or similar.
2328 *
2329 * Return: %0 on success, negative error code otherwise.
2330 */
2331int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2332{
2333 unsigned long vm_len, pfn, pages;
2334
2335 /* Check that the physical memory area passed in looks valid */
2336 if (start + len < start)
2337 return -EINVAL;
2338 /*
2339 * You *really* shouldn't map things that aren't page-aligned,
2340 * but we've historically allowed it because IO memory might
2341 * just have smaller alignment.
2342 */
2343 len += start & ~PAGE_MASK;
2344 pfn = start >> PAGE_SHIFT;
2345 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2346 if (pfn + pages < pfn)
2347 return -EINVAL;
2348
2349 /* We start the mapping 'vm_pgoff' pages into the area */
2350 if (vma->vm_pgoff > pages)
2351 return -EINVAL;
2352 pfn += vma->vm_pgoff;
2353 pages -= vma->vm_pgoff;
2354
2355 /* Can we fit all of the mapping? */
2356 vm_len = vma->vm_end - vma->vm_start;
2357 if (vm_len >> PAGE_SHIFT > pages)
2358 return -EINVAL;
2359
2360 /* Ok, let it rip */
2361 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2362}
2363EXPORT_SYMBOL(vm_iomap_memory);
2364
2365static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2366 unsigned long addr, unsigned long end,
2367 pte_fn_t fn, void *data, bool create,
2368 pgtbl_mod_mask *mask)
2369{
2370 pte_t *pte;
2371 int err = 0;
2372 spinlock_t *ptl;
2373
2374 if (create) {
2375 pte = (mm == &init_mm) ?
2376 pte_alloc_kernel_track(pmd, addr, mask) :
2377 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2378 if (!pte)
2379 return -ENOMEM;
2380 } else {
2381 pte = (mm == &init_mm) ?
2382 pte_offset_kernel(pmd, addr) :
2383 pte_offset_map_lock(mm, pmd, addr, &ptl);
2384 }
2385
2386 BUG_ON(pmd_huge(*pmd));
2387
2388 arch_enter_lazy_mmu_mode();
2389
2390 do {
2391 if (create || !pte_none(*pte)) {
2392 err = fn(pte++, addr, data);
2393 if (err)
2394 break;
2395 }
2396 } while (addr += PAGE_SIZE, addr != end);
2397 *mask |= PGTBL_PTE_MODIFIED;
2398
2399 arch_leave_lazy_mmu_mode();
2400
2401 if (mm != &init_mm)
2402 pte_unmap_unlock(pte-1, ptl);
2403 return err;
2404}
2405
2406static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2407 unsigned long addr, unsigned long end,
2408 pte_fn_t fn, void *data, bool create,
2409 pgtbl_mod_mask *mask)
2410{
2411 pmd_t *pmd;
2412 unsigned long next;
2413 int err = 0;
2414
2415 BUG_ON(pud_huge(*pud));
2416
2417 if (create) {
2418 pmd = pmd_alloc_track(mm, pud, addr, mask);
2419 if (!pmd)
2420 return -ENOMEM;
2421 } else {
2422 pmd = pmd_offset(pud, addr);
2423 }
2424 do {
2425 next = pmd_addr_end(addr, end);
2426 if (create || !pmd_none_or_clear_bad(pmd)) {
2427 err = apply_to_pte_range(mm, pmd, addr, next, fn, data,
2428 create, mask);
2429 if (err)
2430 break;
2431 }
2432 } while (pmd++, addr = next, addr != end);
2433 return err;
2434}
2435
2436static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2437 unsigned long addr, unsigned long end,
2438 pte_fn_t fn, void *data, bool create,
2439 pgtbl_mod_mask *mask)
2440{
2441 pud_t *pud;
2442 unsigned long next;
2443 int err = 0;
2444
2445 if (create) {
2446 pud = pud_alloc_track(mm, p4d, addr, mask);
2447 if (!pud)
2448 return -ENOMEM;
2449 } else {
2450 pud = pud_offset(p4d, addr);
2451 }
2452 do {
2453 next = pud_addr_end(addr, end);
2454 if (create || !pud_none_or_clear_bad(pud)) {
2455 err = apply_to_pmd_range(mm, pud, addr, next, fn, data,
2456 create, mask);
2457 if (err)
2458 break;
2459 }
2460 } while (pud++, addr = next, addr != end);
2461 return err;
2462}
2463
2464static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2465 unsigned long addr, unsigned long end,
2466 pte_fn_t fn, void *data, bool create,
2467 pgtbl_mod_mask *mask)
2468{
2469 p4d_t *p4d;
2470 unsigned long next;
2471 int err = 0;
2472
2473 if (create) {
2474 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2475 if (!p4d)
2476 return -ENOMEM;
2477 } else {
2478 p4d = p4d_offset(pgd, addr);
2479 }
2480 do {
2481 next = p4d_addr_end(addr, end);
2482 if (create || !p4d_none_or_clear_bad(p4d)) {
2483 err = apply_to_pud_range(mm, p4d, addr, next, fn, data,
2484 create, mask);
2485 if (err)
2486 break;
2487 }
2488 } while (p4d++, addr = next, addr != end);
2489 return err;
2490}
2491
2492static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2493 unsigned long size, pte_fn_t fn,
2494 void *data, bool create)
2495{
2496 pgd_t *pgd;
2497 unsigned long start = addr, next;
2498 unsigned long end = addr + size;
2499 pgtbl_mod_mask mask = 0;
2500 int err = 0;
2501
2502 if (WARN_ON(addr >= end))
2503 return -EINVAL;
2504
2505 pgd = pgd_offset(mm, addr);
2506 do {
2507 next = pgd_addr_end(addr, end);
2508 if (!create && pgd_none_or_clear_bad(pgd))
2509 continue;
2510 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create, &mask);
2511 if (err)
2512 break;
2513 } while (pgd++, addr = next, addr != end);
2514
2515 if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2516 arch_sync_kernel_mappings(start, start + size);
2517
2518 return err;
2519}
2520
2521/*
2522 * Scan a region of virtual memory, filling in page tables as necessary
2523 * and calling a provided function on each leaf page table.
2524 */
2525int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2526 unsigned long size, pte_fn_t fn, void *data)
2527{
2528 return __apply_to_page_range(mm, addr, size, fn, data, true);
2529}
2530EXPORT_SYMBOL_GPL(apply_to_page_range);
2531
2532/*
2533 * Scan a region of virtual memory, calling a provided function on
2534 * each leaf page table where it exists.
2535 *
2536 * Unlike apply_to_page_range, this does _not_ fill in page tables
2537 * where they are absent.
2538 */
2539int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
2540 unsigned long size, pte_fn_t fn, void *data)
2541{
2542 return __apply_to_page_range(mm, addr, size, fn, data, false);
2543}
2544EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
2545
2546/*
2547 * handle_pte_fault chooses page fault handler according to an entry which was
2548 * read non-atomically. Before making any commitment, on those architectures
2549 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2550 * parts, do_swap_page must check under lock before unmapping the pte and
2551 * proceeding (but do_wp_page is only called after already making such a check;
2552 * and do_anonymous_page can safely check later on).
2553 */
2554static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2555 pte_t *page_table, pte_t orig_pte)
2556{
2557 int same = 1;
2558#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
2559 if (sizeof(pte_t) > sizeof(unsigned long)) {
2560 spinlock_t *ptl = pte_lockptr(mm, pmd);
2561 spin_lock(ptl);
2562 same = pte_same(*page_table, orig_pte);
2563 spin_unlock(ptl);
2564 }
2565#endif
2566 pte_unmap(page_table);
2567 return same;
2568}
2569
2570static inline bool cow_user_page(struct page *dst, struct page *src,
2571 struct vm_fault *vmf)
2572{
2573 bool ret;
2574 void *kaddr;
2575 void __user *uaddr;
2576 bool locked = false;
2577 struct vm_area_struct *vma = vmf->vma;
2578 struct mm_struct *mm = vma->vm_mm;
2579 unsigned long addr = vmf->address;
2580
2581 if (likely(src)) {
2582 copy_user_highpage(dst, src, addr, vma);
2583 return true;
2584 }
2585
2586 /*
2587 * If the source page was a PFN mapping, we don't have
2588 * a "struct page" for it. We do a best-effort copy by
2589 * just copying from the original user address. If that
2590 * fails, we just zero-fill it. Live with it.
2591 */
2592 kaddr = kmap_atomic(dst);
2593 uaddr = (void __user *)(addr & PAGE_MASK);
2594
2595 /*
2596 * On architectures with software "accessed" bits, we would
2597 * take a double page fault, so mark it accessed here.
2598 */
2599 if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
2600 pte_t entry;
2601
2602 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2603 locked = true;
2604 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2605 /*
2606 * Other thread has already handled the fault
2607 * and update local tlb only
2608 */
2609 update_mmu_tlb(vma, addr, vmf->pte);
2610 ret = false;
2611 goto pte_unlock;
2612 }
2613
2614 entry = pte_mkyoung(vmf->orig_pte);
2615 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
2616 update_mmu_cache(vma, addr, vmf->pte);
2617 }
2618
2619 /*
2620 * This really shouldn't fail, because the page is there
2621 * in the page tables. But it might just be unreadable,
2622 * in which case we just give up and fill the result with
2623 * zeroes.
2624 */
2625 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2626 if (locked)
2627 goto warn;
2628
2629 /* Re-validate under PTL if the page is still mapped */
2630 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
2631 locked = true;
2632 if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2633 /* The PTE changed under us, update local tlb */
2634 update_mmu_tlb(vma, addr, vmf->pte);
2635 ret = false;
2636 goto pte_unlock;
2637 }
2638
2639 /*
2640 * The same page can be mapped back since last copy attempt.
2641 * Try to copy again under PTL.
2642 */
2643 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
2644 /*
2645 * Give a warn in case there can be some obscure
2646 * use-case
2647 */
2648warn:
2649 WARN_ON_ONCE(1);
2650 clear_page(kaddr);
2651 }
2652 }
2653
2654 ret = true;
2655
2656pte_unlock:
2657 if (locked)
2658 pte_unmap_unlock(vmf->pte, vmf->ptl);
2659 kunmap_atomic(kaddr);
2660 flush_dcache_page(dst);
2661
2662 return ret;
2663}
2664
2665static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2666{
2667 struct file *vm_file = vma->vm_file;
2668
2669 if (vm_file)
2670 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2671
2672 /*
2673 * Special mappings (e.g. VDSO) do not have any file so fake
2674 * a default GFP_KERNEL for them.
2675 */
2676 return GFP_KERNEL;
2677}
2678
2679/*
2680 * Notify the address space that the page is about to become writable so that
2681 * it can prohibit this or wait for the page to get into an appropriate state.
2682 *
2683 * We do this without the lock held, so that it can sleep if it needs to.
2684 */
2685static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2686{
2687 vm_fault_t ret;
2688 struct page *page = vmf->page;
2689 unsigned int old_flags = vmf->flags;
2690
2691 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2692
2693 if (vmf->vma->vm_file &&
2694 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2695 return VM_FAULT_SIGBUS;
2696
2697 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2698 /* Restore original flags so that caller is not surprised */
2699 vmf->flags = old_flags;
2700 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2701 return ret;
2702 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2703 lock_page(page);
2704 if (!page->mapping) {
2705 unlock_page(page);
2706 return 0; /* retry */
2707 }
2708 ret |= VM_FAULT_LOCKED;
2709 } else
2710 VM_BUG_ON_PAGE(!PageLocked(page), page);
2711 return ret;
2712}
2713
2714/*
2715 * Handle dirtying of a page in shared file mapping on a write fault.
2716 *
2717 * The function expects the page to be locked and unlocks it.
2718 */
2719static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
2720{
2721 struct vm_area_struct *vma = vmf->vma;
2722 struct address_space *mapping;
2723 struct page *page = vmf->page;
2724 bool dirtied;
2725 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2726
2727 dirtied = set_page_dirty(page);
2728 VM_BUG_ON_PAGE(PageAnon(page), page);
2729 /*
2730 * Take a local copy of the address_space - page.mapping may be zeroed
2731 * by truncate after unlock_page(). The address_space itself remains
2732 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2733 * release semantics to prevent the compiler from undoing this copying.
2734 */
2735 mapping = page_rmapping(page);
2736 unlock_page(page);
2737
2738 if (!page_mkwrite)
2739 file_update_time(vma->vm_file);
2740
2741 /*
2742 * Throttle page dirtying rate down to writeback speed.
2743 *
2744 * mapping may be NULL here because some device drivers do not
2745 * set page.mapping but still dirty their pages
2746 *
2747 * Drop the mmap_lock before waiting on IO, if we can. The file
2748 * is pinning the mapping, as per above.
2749 */
2750 if ((dirtied || page_mkwrite) && mapping) {
2751 struct file *fpin;
2752
2753 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2754 balance_dirty_pages_ratelimited(mapping);
2755 if (fpin) {
2756 fput(fpin);
2757 return VM_FAULT_RETRY;
2758 }
2759 }
2760
2761 return 0;
2762}
2763
2764/*
2765 * Handle write page faults for pages that can be reused in the current vma
2766 *
2767 * This can happen either due to the mapping being with the VM_SHARED flag,
2768 * or due to us being the last reference standing to the page. In either
2769 * case, all we need to do here is to mark the page as writable and update
2770 * any related book-keeping.
2771 */
2772static inline void wp_page_reuse(struct vm_fault *vmf)
2773 __releases(vmf->ptl)
2774{
2775 struct vm_area_struct *vma = vmf->vma;
2776 struct page *page = vmf->page;
2777 pte_t entry;
2778 /*
2779 * Clear the pages cpupid information as the existing
2780 * information potentially belongs to a now completely
2781 * unrelated process.
2782 */
2783 if (page)
2784 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2785
2786 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2787 entry = pte_mkyoung(vmf->orig_pte);
2788 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2789 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2790 update_mmu_cache(vma, vmf->address, vmf->pte);
2791 pte_unmap_unlock(vmf->pte, vmf->ptl);
2792 count_vm_event(PGREUSE);
2793}
2794
2795/*
2796 * Handle the case of a page which we actually need to copy to a new page.
2797 *
2798 * Called with mmap_lock locked and the old page referenced, but
2799 * without the ptl held.
2800 *
2801 * High level logic flow:
2802 *
2803 * - Allocate a page, copy the content of the old page to the new one.
2804 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2805 * - Take the PTL. If the pte changed, bail out and release the allocated page
2806 * - If the pte is still the way we remember it, update the page table and all
2807 * relevant references. This includes dropping the reference the page-table
2808 * held to the old page, as well as updating the rmap.
2809 * - In any case, unlock the PTL and drop the reference we took to the old page.
2810 */
2811static vm_fault_t wp_page_copy(struct vm_fault *vmf)
2812{
2813 struct vm_area_struct *vma = vmf->vma;
2814 struct mm_struct *mm = vma->vm_mm;
2815 struct page *old_page = vmf->page;
2816 struct page *new_page = NULL;
2817 pte_t entry;
2818 int page_copied = 0;
2819 struct mmu_notifier_range range;
2820
2821 if (unlikely(anon_vma_prepare(vma)))
2822 goto oom;
2823
2824 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2825 new_page = alloc_zeroed_user_highpage_movable(vma,
2826 vmf->address);
2827 if (!new_page)
2828 goto oom;
2829 } else {
2830 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2831 vmf->address);
2832 if (!new_page)
2833 goto oom;
2834
2835 if (!cow_user_page(new_page, old_page, vmf)) {
2836 /*
2837 * COW failed, if the fault was solved by other,
2838 * it's fine. If not, userspace would re-fault on
2839 * the same address and we will handle the fault
2840 * from the second attempt.
2841 */
2842 put_page(new_page);
2843 if (old_page)
2844 put_page(old_page);
2845 return 0;
2846 }
2847 }
2848
2849 if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
2850 goto oom_free_new;
2851 cgroup_throttle_swaprate(new_page, GFP_KERNEL);
2852
2853 __SetPageUptodate(new_page);
2854
2855 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
2856 vmf->address & PAGE_MASK,
2857 (vmf->address & PAGE_MASK) + PAGE_SIZE);
2858 mmu_notifier_invalidate_range_start(&range);
2859
2860 /*
2861 * Re-check the pte - we dropped the lock
2862 */
2863 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2864 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2865 if (old_page) {
2866 if (!PageAnon(old_page)) {
2867 dec_mm_counter_fast(mm,
2868 mm_counter_file(old_page));
2869 inc_mm_counter_fast(mm, MM_ANONPAGES);
2870 }
2871 } else {
2872 inc_mm_counter_fast(mm, MM_ANONPAGES);
2873 }
2874 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2875 entry = mk_pte(new_page, vma->vm_page_prot);
2876 entry = pte_sw_mkyoung(entry);
2877 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2878 /*
2879 * Clear the pte entry and flush it first, before updating the
2880 * pte with the new entry. This will avoid a race condition
2881 * seen in the presence of one thread doing SMC and another
2882 * thread doing COW.
2883 */
2884 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2885 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2886 lru_cache_add_inactive_or_unevictable(new_page, vma);
2887 /*
2888 * We call the notify macro here because, when using secondary
2889 * mmu page tables (such as kvm shadow page tables), we want the
2890 * new page to be mapped directly into the secondary page table.
2891 */
2892 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2893 update_mmu_cache(vma, vmf->address, vmf->pte);
2894 if (old_page) {
2895 /*
2896 * Only after switching the pte to the new page may
2897 * we remove the mapcount here. Otherwise another
2898 * process may come and find the rmap count decremented
2899 * before the pte is switched to the new page, and
2900 * "reuse" the old page writing into it while our pte
2901 * here still points into it and can be read by other
2902 * threads.
2903 *
2904 * The critical issue is to order this
2905 * page_remove_rmap with the ptp_clear_flush above.
2906 * Those stores are ordered by (if nothing else,)
2907 * the barrier present in the atomic_add_negative
2908 * in page_remove_rmap.
2909 *
2910 * Then the TLB flush in ptep_clear_flush ensures that
2911 * no process can access the old page before the
2912 * decremented mapcount is visible. And the old page
2913 * cannot be reused until after the decremented
2914 * mapcount is visible. So transitively, TLBs to
2915 * old page will be flushed before it can be reused.
2916 */
2917 page_remove_rmap(old_page, false);
2918 }
2919
2920 /* Free the old page.. */
2921 new_page = old_page;
2922 page_copied = 1;
2923 } else {
2924 update_mmu_tlb(vma, vmf->address, vmf->pte);
2925 }
2926
2927 if (new_page)
2928 put_page(new_page);
2929
2930 pte_unmap_unlock(vmf->pte, vmf->ptl);
2931 /*
2932 * No need to double call mmu_notifier->invalidate_range() callback as
2933 * the above ptep_clear_flush_notify() did already call it.
2934 */
2935 mmu_notifier_invalidate_range_only_end(&range);
2936 if (old_page) {
2937 /*
2938 * Don't let another task, with possibly unlocked vma,
2939 * keep the mlocked page.
2940 */
2941 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2942 lock_page(old_page); /* LRU manipulation */
2943 if (PageMlocked(old_page))
2944 munlock_vma_page(old_page);
2945 unlock_page(old_page);
2946 }
2947 put_page(old_page);
2948 }
2949 return page_copied ? VM_FAULT_WRITE : 0;
2950oom_free_new:
2951 put_page(new_page);
2952oom:
2953 if (old_page)
2954 put_page(old_page);
2955 return VM_FAULT_OOM;
2956}
2957
2958/**
2959 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2960 * writeable once the page is prepared
2961 *
2962 * @vmf: structure describing the fault
2963 *
2964 * This function handles all that is needed to finish a write page fault in a
2965 * shared mapping due to PTE being read-only once the mapped page is prepared.
2966 * It handles locking of PTE and modifying it.
2967 *
2968 * The function expects the page to be locked or other protection against
2969 * concurrent faults / writeback (such as DAX radix tree locks).
2970 *
2971 * Return: %VM_FAULT_WRITE on success, %0 when PTE got changed before
2972 * we acquired PTE lock.
2973 */
2974vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
2975{
2976 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2977 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2978 &vmf->ptl);
2979 /*
2980 * We might have raced with another page fault while we released the
2981 * pte_offset_map_lock.
2982 */
2983 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2984 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
2985 pte_unmap_unlock(vmf->pte, vmf->ptl);
2986 return VM_FAULT_NOPAGE;
2987 }
2988 wp_page_reuse(vmf);
2989 return 0;
2990}
2991
2992/*
2993 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2994 * mapping
2995 */
2996static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
2997{
2998 struct vm_area_struct *vma = vmf->vma;
2999
3000 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3001 vm_fault_t ret;
3002
3003 pte_unmap_unlock(vmf->pte, vmf->ptl);
3004 vmf->flags |= FAULT_FLAG_MKWRITE;
3005 ret = vma->vm_ops->pfn_mkwrite(vmf);
3006 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3007 return ret;
3008 return finish_mkwrite_fault(vmf);
3009 }
3010 wp_page_reuse(vmf);
3011 return VM_FAULT_WRITE;
3012}
3013
3014static vm_fault_t wp_page_shared(struct vm_fault *vmf)
3015 __releases(vmf->ptl)
3016{
3017 struct vm_area_struct *vma = vmf->vma;
3018 vm_fault_t ret = VM_FAULT_WRITE;
3019
3020 get_page(vmf->page);
3021
3022 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3023 vm_fault_t tmp;
3024
3025 pte_unmap_unlock(vmf->pte, vmf->ptl);
3026 tmp = do_page_mkwrite(vmf);
3027 if (unlikely(!tmp || (tmp &
3028 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3029 put_page(vmf->page);
3030 return tmp;
3031 }
3032 tmp = finish_mkwrite_fault(vmf);
3033 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3034 unlock_page(vmf->page);
3035 put_page(vmf->page);
3036 return tmp;
3037 }
3038 } else {
3039 wp_page_reuse(vmf);
3040 lock_page(vmf->page);
3041 }
3042 ret |= fault_dirty_shared_page(vmf);
3043 put_page(vmf->page);
3044
3045 return ret;
3046}
3047
3048/*
3049 * This routine handles present pages, when users try to write
3050 * to a shared page. It is done by copying the page to a new address
3051 * and decrementing the shared-page counter for the old page.
3052 *
3053 * Note that this routine assumes that the protection checks have been
3054 * done by the caller (the low-level page fault routine in most cases).
3055 * Thus we can safely just mark it writable once we've done any necessary
3056 * COW.
3057 *
3058 * We also mark the page dirty at this point even though the page will
3059 * change only once the write actually happens. This avoids a few races,
3060 * and potentially makes it more efficient.
3061 *
3062 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3063 * but allow concurrent faults), with pte both mapped and locked.
3064 * We return with mmap_lock still held, but pte unmapped and unlocked.
3065 */
3066static vm_fault_t do_wp_page(struct vm_fault *vmf)
3067 __releases(vmf->ptl)
3068{
3069 struct vm_area_struct *vma = vmf->vma;
3070
3071 if (userfaultfd_pte_wp(vma, *vmf->pte)) {
3072 pte_unmap_unlock(vmf->pte, vmf->ptl);
3073 return handle_userfault(vmf, VM_UFFD_WP);
3074 }
3075
3076 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3077 if (!vmf->page) {
3078 /*
3079 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3080 * VM_PFNMAP VMA.
3081 *
3082 * We should not cow pages in a shared writeable mapping.
3083 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3084 */
3085 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
3086 (VM_WRITE|VM_SHARED))
3087 return wp_pfn_shared(vmf);
3088
3089 pte_unmap_unlock(vmf->pte, vmf->ptl);
3090 return wp_page_copy(vmf);
3091 }
3092
3093 /*
3094 * Take out anonymous pages first, anonymous shared vmas are
3095 * not dirty accountable.
3096 */
3097 if (PageAnon(vmf->page)) {
3098 struct page *page = vmf->page;
3099
3100 /* PageKsm() doesn't necessarily raise the page refcount */
3101 if (PageKsm(page) || page_count(page) != 1)
3102 goto copy;
3103 if (!trylock_page(page))
3104 goto copy;
3105 if (PageKsm(page) || page_mapcount(page) != 1 || page_count(page) != 1) {
3106 unlock_page(page);
3107 goto copy;
3108 }
3109 /*
3110 * Ok, we've got the only map reference, and the only
3111 * page count reference, and the page is locked,
3112 * it's dark out, and we're wearing sunglasses. Hit it.
3113 */
3114 unlock_page(page);
3115 wp_page_reuse(vmf);
3116 return VM_FAULT_WRITE;
3117 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
3118 (VM_WRITE|VM_SHARED))) {
3119 return wp_page_shared(vmf);
3120 }
3121copy:
3122 /*
3123 * Ok, we need to copy. Oh, well..
3124 */
3125 get_page(vmf->page);
3126
3127 pte_unmap_unlock(vmf->pte, vmf->ptl);
3128 return wp_page_copy(vmf);
3129}
3130
3131static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3132 unsigned long start_addr, unsigned long end_addr,
3133 struct zap_details *details)
3134{
3135 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3136}
3137
3138static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3139 struct zap_details *details)
3140{
3141 struct vm_area_struct *vma;
3142 pgoff_t vba, vea, zba, zea;
3143
3144 vma_interval_tree_foreach(vma, root,
3145 details->first_index, details->last_index) {
3146
3147 vba = vma->vm_pgoff;
3148 vea = vba + vma_pages(vma) - 1;
3149 zba = details->first_index;
3150 if (zba < vba)
3151 zba = vba;
3152 zea = details->last_index;
3153 if (zea > vea)
3154 zea = vea;
3155
3156 unmap_mapping_range_vma(vma,
3157 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3158 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3159 details);
3160 }
3161}
3162
3163/**
3164 * unmap_mapping_pages() - Unmap pages from processes.
3165 * @mapping: The address space containing pages to be unmapped.
3166 * @start: Index of first page to be unmapped.
3167 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3168 * @even_cows: Whether to unmap even private COWed pages.
3169 *
3170 * Unmap the pages in this address space from any userspace process which
3171 * has them mmaped. Generally, you want to remove COWed pages as well when
3172 * a file is being truncated, but not when invalidating pages from the page
3173 * cache.
3174 */
3175void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3176 pgoff_t nr, bool even_cows)
3177{
3178 struct zap_details details = { };
3179
3180 details.check_mapping = even_cows ? NULL : mapping;
3181 details.first_index = start;
3182 details.last_index = start + nr - 1;
3183 if (details.last_index < details.first_index)
3184 details.last_index = ULONG_MAX;
3185
3186 i_mmap_lock_write(mapping);
3187 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3188 unmap_mapping_range_tree(&mapping->i_mmap, &details);
3189 i_mmap_unlock_write(mapping);
3190}
3191
3192/**
3193 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3194 * address_space corresponding to the specified byte range in the underlying
3195 * file.
3196 *
3197 * @mapping: the address space containing mmaps to be unmapped.
3198 * @holebegin: byte in first page to unmap, relative to the start of
3199 * the underlying file. This will be rounded down to a PAGE_SIZE
3200 * boundary. Note that this is different from truncate_pagecache(), which
3201 * must keep the partial page. In contrast, we must get rid of
3202 * partial pages.
3203 * @holelen: size of prospective hole in bytes. This will be rounded
3204 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3205 * end of the file.
3206 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3207 * but 0 when invalidating pagecache, don't throw away private data.
3208 */
3209void unmap_mapping_range(struct address_space *mapping,
3210 loff_t const holebegin, loff_t const holelen, int even_cows)
3211{
3212 pgoff_t hba = holebegin >> PAGE_SHIFT;
3213 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3214
3215 /* Check for overflow. */
3216 if (sizeof(holelen) > sizeof(hlen)) {
3217 long long holeend =
3218 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3219 if (holeend & ~(long long)ULONG_MAX)
3220 hlen = ULONG_MAX - hba + 1;
3221 }
3222
3223 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3224}
3225EXPORT_SYMBOL(unmap_mapping_range);
3226
3227/*
3228 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3229 * but allow concurrent faults), and pte mapped but not yet locked.
3230 * We return with pte unmapped and unlocked.
3231 *
3232 * We return with the mmap_lock locked or unlocked in the same cases
3233 * as does filemap_fault().
3234 */
3235vm_fault_t do_swap_page(struct vm_fault *vmf)
3236{
3237 struct vm_area_struct *vma = vmf->vma;
3238 struct page *page = NULL, *swapcache;
3239 swp_entry_t entry;
3240 pte_t pte;
3241 int locked;
3242 int exclusive = 0;
3243 vm_fault_t ret = 0;
3244 void *shadow = NULL;
3245
3246 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
3247 goto out;
3248
3249 entry = pte_to_swp_entry(vmf->orig_pte);
3250 if (unlikely(non_swap_entry(entry))) {
3251 if (is_migration_entry(entry)) {
3252 migration_entry_wait(vma->vm_mm, vmf->pmd,
3253 vmf->address);
3254 } else if (is_device_private_entry(entry)) {
3255 vmf->page = device_private_entry_to_page(entry);
3256 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
3257 } else if (is_hwpoison_entry(entry)) {
3258 ret = VM_FAULT_HWPOISON;
3259 } else {
3260 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
3261 ret = VM_FAULT_SIGBUS;
3262 }
3263 goto out;
3264 }
3265
3266
3267 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
3268 page = lookup_swap_cache(entry, vma, vmf->address);
3269 swapcache = page;
3270
3271 if (!page) {
3272 struct swap_info_struct *si = swp_swap_info(entry);
3273
3274 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
3275 __swap_count(entry) == 1) {
3276 /* skip swapcache */
3277 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
3278 vmf->address);
3279 if (page) {
3280 int err;
3281
3282 __SetPageLocked(page);
3283 __SetPageSwapBacked(page);
3284 set_page_private(page, entry.val);
3285
3286 /* Tell memcg to use swap ownership records */
3287 SetPageSwapCache(page);
3288 err = mem_cgroup_charge(page, vma->vm_mm,
3289 GFP_KERNEL);
3290 ClearPageSwapCache(page);
3291 if (err) {
3292 ret = VM_FAULT_OOM;
3293 goto out_page;
3294 }
3295
3296 shadow = get_shadow_from_swap_cache(entry);
3297 if (shadow)
3298 workingset_refault(page, shadow);
3299
3300 lru_cache_add(page);
3301 swap_readpage(page, true);
3302 }
3303 } else {
3304 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
3305 vmf);
3306 swapcache = page;
3307 }
3308
3309 if (!page) {
3310 /*
3311 * Back out if somebody else faulted in this pte
3312 * while we released the pte lock.
3313 */
3314 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3315 vmf->address, &vmf->ptl);
3316 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
3317 ret = VM_FAULT_OOM;
3318 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3319 goto unlock;
3320 }
3321
3322 /* Had to read the page from swap area: Major fault */
3323 ret = VM_FAULT_MAJOR;
3324 count_vm_event(PGMAJFAULT);
3325 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
3326 } else if (PageHWPoison(page)) {
3327 /*
3328 * hwpoisoned dirty swapcache pages are kept for killing
3329 * owner processes (which may be unknown at hwpoison time)
3330 */
3331 ret = VM_FAULT_HWPOISON;
3332 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3333 goto out_release;
3334 }
3335
3336 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
3337
3338 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3339 if (!locked) {
3340 ret |= VM_FAULT_RETRY;
3341 goto out_release;
3342 }
3343
3344 /*
3345 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3346 * release the swapcache from under us. The page pin, and pte_same
3347 * test below, are not enough to exclude that. Even if it is still
3348 * swapcache, we need to check that the page's swap has not changed.
3349 */
3350 if (unlikely((!PageSwapCache(page) ||
3351 page_private(page) != entry.val)) && swapcache)
3352 goto out_page;
3353
3354 page = ksm_might_need_to_copy(page, vma, vmf->address);
3355 if (unlikely(!page)) {
3356 ret = VM_FAULT_OOM;
3357 page = swapcache;
3358 goto out_page;
3359 }
3360
3361 cgroup_throttle_swaprate(page, GFP_KERNEL);
3362
3363 /*
3364 * Back out if somebody else already faulted in this pte.
3365 */
3366 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3367 &vmf->ptl);
3368 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3369 goto out_nomap;
3370
3371 if (unlikely(!PageUptodate(page))) {
3372 ret = VM_FAULT_SIGBUS;
3373 goto out_nomap;
3374 }
3375
3376 /*
3377 * The page isn't present yet, go ahead with the fault.
3378 *
3379 * Be careful about the sequence of operations here.
3380 * To get its accounting right, reuse_swap_page() must be called
3381 * while the page is counted on swap but not yet in mapcount i.e.
3382 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3383 * must be called after the swap_free(), or it will never succeed.
3384 */
3385
3386 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3387 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3388 pte = mk_pte(page, vma->vm_page_prot);
3389 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
3390 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3391 vmf->flags &= ~FAULT_FLAG_WRITE;
3392 ret |= VM_FAULT_WRITE;
3393 exclusive = RMAP_EXCLUSIVE;
3394 }
3395 flush_icache_page(vma, page);
3396 if (pte_swp_soft_dirty(vmf->orig_pte))
3397 pte = pte_mksoft_dirty(pte);
3398 if (pte_swp_uffd_wp(vmf->orig_pte)) {
3399 pte = pte_mkuffd_wp(pte);
3400 pte = pte_wrprotect(pte);
3401 }
3402 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3403 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3404 vmf->orig_pte = pte;
3405
3406 /* ksm created a completely new copy */
3407 if (unlikely(page != swapcache && swapcache)) {
3408 page_add_new_anon_rmap(page, vma, vmf->address, false);
3409 lru_cache_add_inactive_or_unevictable(page, vma);
3410 } else {
3411 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3412 }
3413
3414 swap_free(entry);
3415 if (mem_cgroup_swap_full(page) ||
3416 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3417 try_to_free_swap(page);
3418 unlock_page(page);
3419 if (page != swapcache && swapcache) {
3420 /*
3421 * Hold the lock to avoid the swap entry to be reused
3422 * until we take the PT lock for the pte_same() check
3423 * (to avoid false positives from pte_same). For
3424 * further safety release the lock after the swap_free
3425 * so that the swap count won't change under a
3426 * parallel locked swapcache.
3427 */
3428 unlock_page(swapcache);
3429 put_page(swapcache);
3430 }
3431
3432 if (vmf->flags & FAULT_FLAG_WRITE) {
3433 ret |= do_wp_page(vmf);
3434 if (ret & VM_FAULT_ERROR)
3435 ret &= VM_FAULT_ERROR;
3436 goto out;
3437 }
3438
3439 /* No need to invalidate - it was non-present before */
3440 update_mmu_cache(vma, vmf->address, vmf->pte);
3441unlock:
3442 pte_unmap_unlock(vmf->pte, vmf->ptl);
3443out:
3444 return ret;
3445out_nomap:
3446 pte_unmap_unlock(vmf->pte, vmf->ptl);
3447out_page:
3448 unlock_page(page);
3449out_release:
3450 put_page(page);
3451 if (page != swapcache && swapcache) {
3452 unlock_page(swapcache);
3453 put_page(swapcache);
3454 }
3455 return ret;
3456}
3457
3458/*
3459 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3460 * but allow concurrent faults), and pte mapped but not yet locked.
3461 * We return with mmap_lock still held, but pte unmapped and unlocked.
3462 */
3463static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
3464{
3465 struct vm_area_struct *vma = vmf->vma;
3466 struct page *page;
3467 vm_fault_t ret = 0;
3468 pte_t entry;
3469
3470 /* File mapping without ->vm_ops ? */
3471 if (vma->vm_flags & VM_SHARED)
3472 return VM_FAULT_SIGBUS;
3473
3474 /*
3475 * Use pte_alloc() instead of pte_alloc_map(). We can't run
3476 * pte_offset_map() on pmds where a huge pmd might be created
3477 * from a different thread.
3478 *
3479 * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
3480 * parallel threads are excluded by other means.
3481 *
3482 * Here we only have mmap_read_lock(mm).
3483 */
3484 if (pte_alloc(vma->vm_mm, vmf->pmd))
3485 return VM_FAULT_OOM;
3486
3487 /* See the comment in pte_alloc_one_map() */
3488 if (unlikely(pmd_trans_unstable(vmf->pmd)))
3489 return 0;
3490
3491 /* Use the zero-page for reads */
3492 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3493 !mm_forbids_zeropage(vma->vm_mm)) {
3494 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3495 vma->vm_page_prot));
3496 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3497 vmf->address, &vmf->ptl);
3498 if (!pte_none(*vmf->pte)) {
3499 update_mmu_tlb(vma, vmf->address, vmf->pte);
3500 goto unlock;
3501 }
3502 ret = check_stable_address_space(vma->vm_mm);
3503 if (ret)
3504 goto unlock;
3505 /* Deliver the page fault to userland, check inside PT lock */
3506 if (userfaultfd_missing(vma)) {
3507 pte_unmap_unlock(vmf->pte, vmf->ptl);
3508 return handle_userfault(vmf, VM_UFFD_MISSING);
3509 }
3510 goto setpte;
3511 }
3512
3513 /* Allocate our own private page. */
3514 if (unlikely(anon_vma_prepare(vma)))
3515 goto oom;
3516 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3517 if (!page)
3518 goto oom;
3519
3520 if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
3521 goto oom_free_page;
3522 cgroup_throttle_swaprate(page, GFP_KERNEL);
3523
3524 /*
3525 * The memory barrier inside __SetPageUptodate makes sure that
3526 * preceding stores to the page contents become visible before
3527 * the set_pte_at() write.
3528 */
3529 __SetPageUptodate(page);
3530
3531 entry = mk_pte(page, vma->vm_page_prot);
3532 entry = pte_sw_mkyoung(entry);
3533 if (vma->vm_flags & VM_WRITE)
3534 entry = pte_mkwrite(pte_mkdirty(entry));
3535
3536 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3537 &vmf->ptl);
3538 if (!pte_none(*vmf->pte)) {
3539 update_mmu_cache(vma, vmf->address, vmf->pte);
3540 goto release;
3541 }
3542
3543 ret = check_stable_address_space(vma->vm_mm);
3544 if (ret)
3545 goto release;
3546
3547 /* Deliver the page fault to userland, check inside PT lock */
3548 if (userfaultfd_missing(vma)) {
3549 pte_unmap_unlock(vmf->pte, vmf->ptl);
3550 put_page(page);
3551 return handle_userfault(vmf, VM_UFFD_MISSING);
3552 }
3553
3554 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3555 page_add_new_anon_rmap(page, vma, vmf->address, false);
3556 lru_cache_add_inactive_or_unevictable(page, vma);
3557setpte:
3558 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3559
3560 /* No need to invalidate - it was non-present before */
3561 update_mmu_cache(vma, vmf->address, vmf->pte);
3562unlock:
3563 pte_unmap_unlock(vmf->pte, vmf->ptl);
3564 return ret;
3565release:
3566 put_page(page);
3567 goto unlock;
3568oom_free_page:
3569 put_page(page);
3570oom:
3571 return VM_FAULT_OOM;
3572}
3573
3574/*
3575 * The mmap_lock must have been held on entry, and may have been
3576 * released depending on flags and vma->vm_ops->fault() return value.
3577 * See filemap_fault() and __lock_page_retry().
3578 */
3579static vm_fault_t __do_fault(struct vm_fault *vmf)
3580{
3581 struct vm_area_struct *vma = vmf->vma;
3582 vm_fault_t ret;
3583
3584 /*
3585 * Preallocate pte before we take page_lock because this might lead to
3586 * deadlocks for memcg reclaim which waits for pages under writeback:
3587 * lock_page(A)
3588 * SetPageWriteback(A)
3589 * unlock_page(A)
3590 * lock_page(B)
3591 * lock_page(B)
3592 * pte_alloc_pne
3593 * shrink_page_list
3594 * wait_on_page_writeback(A)
3595 * SetPageWriteback(B)
3596 * unlock_page(B)
3597 * # flush A, B to clear the writeback
3598 */
3599 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
3600 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
3601 if (!vmf->prealloc_pte)
3602 return VM_FAULT_OOM;
3603 smp_wmb(); /* See comment in __pte_alloc() */
3604 }
3605
3606 ret = vma->vm_ops->fault(vmf);
3607 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3608 VM_FAULT_DONE_COW)))
3609 return ret;
3610
3611 if (unlikely(PageHWPoison(vmf->page))) {
3612 if (ret & VM_FAULT_LOCKED)
3613 unlock_page(vmf->page);
3614 put_page(vmf->page);
3615 vmf->page = NULL;
3616 return VM_FAULT_HWPOISON;
3617 }
3618
3619 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3620 lock_page(vmf->page);
3621 else
3622 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3623
3624 return ret;
3625}
3626
3627/*
3628 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3629 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3630 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3631 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3632 */
3633static int pmd_devmap_trans_unstable(pmd_t *pmd)
3634{
3635 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3636}
3637
3638static vm_fault_t pte_alloc_one_map(struct vm_fault *vmf)
3639{
3640 struct vm_area_struct *vma = vmf->vma;
3641
3642 if (!pmd_none(*vmf->pmd))
3643 goto map_pte;
3644 if (vmf->prealloc_pte) {
3645 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3646 if (unlikely(!pmd_none(*vmf->pmd))) {
3647 spin_unlock(vmf->ptl);
3648 goto map_pte;
3649 }
3650
3651 mm_inc_nr_ptes(vma->vm_mm);
3652 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3653 spin_unlock(vmf->ptl);
3654 vmf->prealloc_pte = NULL;
3655 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) {
3656 return VM_FAULT_OOM;
3657 }
3658map_pte:
3659 /*
3660 * If a huge pmd materialized under us just retry later. Use
3661 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3662 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3663 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3664 * running immediately after a huge pmd fault in a different thread of
3665 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3666 * All we have to ensure is that it is a regular pmd that we can walk
3667 * with pte_offset_map() and we can do that through an atomic read in
3668 * C, which is what pmd_trans_unstable() provides.
3669 */
3670 if (pmd_devmap_trans_unstable(vmf->pmd))
3671 return VM_FAULT_NOPAGE;
3672
3673 /*
3674 * At this point we know that our vmf->pmd points to a page of ptes
3675 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3676 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3677 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3678 * be valid and we will re-check to make sure the vmf->pte isn't
3679 * pte_none() under vmf->ptl protection when we return to
3680 * alloc_set_pte().
3681 */
3682 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3683 &vmf->ptl);
3684 return 0;
3685}
3686
3687#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3688static void deposit_prealloc_pte(struct vm_fault *vmf)
3689{
3690 struct vm_area_struct *vma = vmf->vma;
3691
3692 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3693 /*
3694 * We are going to consume the prealloc table,
3695 * count that as nr_ptes.
3696 */
3697 mm_inc_nr_ptes(vma->vm_mm);
3698 vmf->prealloc_pte = NULL;
3699}
3700
3701static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3702{
3703 struct vm_area_struct *vma = vmf->vma;
3704 bool write = vmf->flags & FAULT_FLAG_WRITE;
3705 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3706 pmd_t entry;
3707 int i;
3708 vm_fault_t ret;
3709
3710 if (!transhuge_vma_suitable(vma, haddr))
3711 return VM_FAULT_FALLBACK;
3712
3713 ret = VM_FAULT_FALLBACK;
3714 page = compound_head(page);
3715
3716 /*
3717 * Archs like ppc64 need additonal space to store information
3718 * related to pte entry. Use the preallocated table for that.
3719 */
3720 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3721 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3722 if (!vmf->prealloc_pte)
3723 return VM_FAULT_OOM;
3724 smp_wmb(); /* See comment in __pte_alloc() */
3725 }
3726
3727 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3728 if (unlikely(!pmd_none(*vmf->pmd)))
3729 goto out;
3730
3731 for (i = 0; i < HPAGE_PMD_NR; i++)
3732 flush_icache_page(vma, page + i);
3733
3734 entry = mk_huge_pmd(page, vma->vm_page_prot);
3735 if (write)
3736 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3737
3738 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
3739 page_add_file_rmap(page, true);
3740 /*
3741 * deposit and withdraw with pmd lock held
3742 */
3743 if (arch_needs_pgtable_deposit())
3744 deposit_prealloc_pte(vmf);
3745
3746 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3747
3748 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3749
3750 /* fault is handled */
3751 ret = 0;
3752 count_vm_event(THP_FILE_MAPPED);
3753out:
3754 spin_unlock(vmf->ptl);
3755 return ret;
3756}
3757#else
3758static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3759{
3760 BUILD_BUG();
3761 return 0;
3762}
3763#endif
3764
3765/**
3766 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3767 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3768 *
3769 * @vmf: fault environment
3770 * @page: page to map
3771 *
3772 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3773 * return.
3774 *
3775 * Target users are page handler itself and implementations of
3776 * vm_ops->map_pages.
3777 *
3778 * Return: %0 on success, %VM_FAULT_ code in case of error.
3779 */
3780vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct page *page)
3781{
3782 struct vm_area_struct *vma = vmf->vma;
3783 bool write = vmf->flags & FAULT_FLAG_WRITE;
3784 pte_t entry;
3785 vm_fault_t ret;
3786
3787 if (pmd_none(*vmf->pmd) && PageTransCompound(page)) {
3788 ret = do_set_pmd(vmf, page);
3789 if (ret != VM_FAULT_FALLBACK)
3790 return ret;
3791 }
3792
3793 if (!vmf->pte) {
3794 ret = pte_alloc_one_map(vmf);
3795 if (ret)
3796 return ret;
3797 }
3798
3799 /* Re-check under ptl */
3800 if (unlikely(!pte_none(*vmf->pte))) {
3801 update_mmu_tlb(vma, vmf->address, vmf->pte);
3802 return VM_FAULT_NOPAGE;
3803 }
3804
3805 flush_icache_page(vma, page);
3806 entry = mk_pte(page, vma->vm_page_prot);
3807 entry = pte_sw_mkyoung(entry);
3808 if (write)
3809 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3810 /* copy-on-write page */
3811 if (write && !(vma->vm_flags & VM_SHARED)) {
3812 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3813 page_add_new_anon_rmap(page, vma, vmf->address, false);
3814 lru_cache_add_inactive_or_unevictable(page, vma);
3815 } else {
3816 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3817 page_add_file_rmap(page, false);
3818 }
3819 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3820
3821 /* no need to invalidate: a not-present page won't be cached */
3822 update_mmu_cache(vma, vmf->address, vmf->pte);
3823
3824 return 0;
3825}
3826
3827
3828/**
3829 * finish_fault - finish page fault once we have prepared the page to fault
3830 *
3831 * @vmf: structure describing the fault
3832 *
3833 * This function handles all that is needed to finish a page fault once the
3834 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3835 * given page, adds reverse page mapping, handles memcg charges and LRU
3836 * addition.
3837 *
3838 * The function expects the page to be locked and on success it consumes a
3839 * reference of a page being mapped (for the PTE which maps it).
3840 *
3841 * Return: %0 on success, %VM_FAULT_ code in case of error.
3842 */
3843vm_fault_t finish_fault(struct vm_fault *vmf)
3844{
3845 struct page *page;
3846 vm_fault_t ret = 0;
3847
3848 /* Did we COW the page? */
3849 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3850 !(vmf->vma->vm_flags & VM_SHARED))
3851 page = vmf->cow_page;
3852 else
3853 page = vmf->page;
3854
3855 /*
3856 * check even for read faults because we might have lost our CoWed
3857 * page
3858 */
3859 if (!(vmf->vma->vm_flags & VM_SHARED))
3860 ret = check_stable_address_space(vmf->vma->vm_mm);
3861 if (!ret)
3862 ret = alloc_set_pte(vmf, page);
3863 if (vmf->pte)
3864 pte_unmap_unlock(vmf->pte, vmf->ptl);
3865 return ret;
3866}
3867
3868static unsigned long fault_around_bytes __read_mostly =
3869 rounddown_pow_of_two(65536);
3870
3871#ifdef CONFIG_DEBUG_FS
3872static int fault_around_bytes_get(void *data, u64 *val)
3873{
3874 *val = fault_around_bytes;
3875 return 0;
3876}
3877
3878/*
3879 * fault_around_bytes must be rounded down to the nearest page order as it's
3880 * what do_fault_around() expects to see.
3881 */
3882static int fault_around_bytes_set(void *data, u64 val)
3883{
3884 if (val / PAGE_SIZE > PTRS_PER_PTE)
3885 return -EINVAL;
3886 if (val > PAGE_SIZE)
3887 fault_around_bytes = rounddown_pow_of_two(val);
3888 else
3889 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3890 return 0;
3891}
3892DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3893 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3894
3895static int __init fault_around_debugfs(void)
3896{
3897 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3898 &fault_around_bytes_fops);
3899 return 0;
3900}
3901late_initcall(fault_around_debugfs);
3902#endif
3903
3904/*
3905 * do_fault_around() tries to map few pages around the fault address. The hope
3906 * is that the pages will be needed soon and this will lower the number of
3907 * faults to handle.
3908 *
3909 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3910 * not ready to be mapped: not up-to-date, locked, etc.
3911 *
3912 * This function is called with the page table lock taken. In the split ptlock
3913 * case the page table lock only protects only those entries which belong to
3914 * the page table corresponding to the fault address.
3915 *
3916 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3917 * only once.
3918 *
3919 * fault_around_bytes defines how many bytes we'll try to map.
3920 * do_fault_around() expects it to be set to a power of two less than or equal
3921 * to PTRS_PER_PTE.
3922 *
3923 * The virtual address of the area that we map is naturally aligned to
3924 * fault_around_bytes rounded down to the machine page size
3925 * (and therefore to page order). This way it's easier to guarantee
3926 * that we don't cross page table boundaries.
3927 */
3928static vm_fault_t do_fault_around(struct vm_fault *vmf)
3929{
3930 unsigned long address = vmf->address, nr_pages, mask;
3931 pgoff_t start_pgoff = vmf->pgoff;
3932 pgoff_t end_pgoff;
3933 int off;
3934 vm_fault_t ret = 0;
3935
3936 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3937 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3938
3939 vmf->address = max(address & mask, vmf->vma->vm_start);
3940 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3941 start_pgoff -= off;
3942
3943 /*
3944 * end_pgoff is either the end of the page table, the end of
3945 * the vma or nr_pages from start_pgoff, depending what is nearest.
3946 */
3947 end_pgoff = start_pgoff -
3948 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3949 PTRS_PER_PTE - 1;
3950 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3951 start_pgoff + nr_pages - 1);
3952
3953 if (pmd_none(*vmf->pmd)) {
3954 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
3955 if (!vmf->prealloc_pte)
3956 goto out;
3957 smp_wmb(); /* See comment in __pte_alloc() */
3958 }
3959
3960 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3961
3962 /* Huge page is mapped? Page fault is solved */
3963 if (pmd_trans_huge(*vmf->pmd)) {
3964 ret = VM_FAULT_NOPAGE;
3965 goto out;
3966 }
3967
3968 /* ->map_pages() haven't done anything useful. Cold page cache? */
3969 if (!vmf->pte)
3970 goto out;
3971
3972 /* check if the page fault is solved */
3973 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3974 if (!pte_none(*vmf->pte))
3975 ret = VM_FAULT_NOPAGE;
3976 pte_unmap_unlock(vmf->pte, vmf->ptl);
3977out:
3978 vmf->address = address;
3979 vmf->pte = NULL;
3980 return ret;
3981}
3982
3983static vm_fault_t do_read_fault(struct vm_fault *vmf)
3984{
3985 struct vm_area_struct *vma = vmf->vma;
3986 vm_fault_t ret = 0;
3987
3988 /*
3989 * Let's call ->map_pages() first and use ->fault() as fallback
3990 * if page by the offset is not ready to be mapped (cold cache or
3991 * something).
3992 */
3993 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3994 ret = do_fault_around(vmf);
3995 if (ret)
3996 return ret;
3997 }
3998
3999 ret = __do_fault(vmf);
4000 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4001 return ret;
4002
4003 ret |= finish_fault(vmf);
4004 unlock_page(vmf->page);
4005 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4006 put_page(vmf->page);
4007 return ret;
4008}
4009
4010static vm_fault_t do_cow_fault(struct vm_fault *vmf)
4011{
4012 struct vm_area_struct *vma = vmf->vma;
4013 vm_fault_t ret;
4014
4015 if (unlikely(anon_vma_prepare(vma)))
4016 return VM_FAULT_OOM;
4017
4018 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
4019 if (!vmf->cow_page)
4020 return VM_FAULT_OOM;
4021
4022 if (mem_cgroup_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL)) {
4023 put_page(vmf->cow_page);
4024 return VM_FAULT_OOM;
4025 }
4026 cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL);
4027
4028 ret = __do_fault(vmf);
4029 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4030 goto uncharge_out;
4031 if (ret & VM_FAULT_DONE_COW)
4032 return ret;
4033
4034 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
4035 __SetPageUptodate(vmf->cow_page);
4036
4037 ret |= finish_fault(vmf);
4038 unlock_page(vmf->page);
4039 put_page(vmf->page);
4040 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4041 goto uncharge_out;
4042 return ret;
4043uncharge_out:
4044 put_page(vmf->cow_page);
4045 return ret;
4046}
4047
4048static vm_fault_t do_shared_fault(struct vm_fault *vmf)
4049{
4050 struct vm_area_struct *vma = vmf->vma;
4051 vm_fault_t ret, tmp;
4052
4053 ret = __do_fault(vmf);
4054 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
4055 return ret;
4056
4057 /*
4058 * Check if the backing address space wants to know that the page is
4059 * about to become writable
4060 */
4061 if (vma->vm_ops->page_mkwrite) {
4062 unlock_page(vmf->page);
4063 tmp = do_page_mkwrite(vmf);
4064 if (unlikely(!tmp ||
4065 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
4066 put_page(vmf->page);
4067 return tmp;
4068 }
4069 }
4070
4071 ret |= finish_fault(vmf);
4072 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
4073 VM_FAULT_RETRY))) {
4074 unlock_page(vmf->page);
4075 put_page(vmf->page);
4076 return ret;
4077 }
4078
4079 ret |= fault_dirty_shared_page(vmf);
4080 return ret;
4081}
4082
4083/*
4084 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4085 * but allow concurrent faults).
4086 * The mmap_lock may have been released depending on flags and our
4087 * return value. See filemap_fault() and __lock_page_or_retry().
4088 * If mmap_lock is released, vma may become invalid (for example
4089 * by other thread calling munmap()).
4090 */
4091static vm_fault_t do_fault(struct vm_fault *vmf)
4092{
4093 struct vm_area_struct *vma = vmf->vma;
4094 struct mm_struct *vm_mm = vma->vm_mm;
4095 vm_fault_t ret;
4096
4097 /*
4098 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
4099 */
4100 if (!vma->vm_ops->fault) {
4101 /*
4102 * If we find a migration pmd entry or a none pmd entry, which
4103 * should never happen, return SIGBUS
4104 */
4105 if (unlikely(!pmd_present(*vmf->pmd)))
4106 ret = VM_FAULT_SIGBUS;
4107 else {
4108 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
4109 vmf->pmd,
4110 vmf->address,
4111 &vmf->ptl);
4112 /*
4113 * Make sure this is not a temporary clearing of pte
4114 * by holding ptl and checking again. A R/M/W update
4115 * of pte involves: take ptl, clearing the pte so that
4116 * we don't have concurrent modification by hardware
4117 * followed by an update.
4118 */
4119 if (unlikely(pte_none(*vmf->pte)))
4120 ret = VM_FAULT_SIGBUS;
4121 else
4122 ret = VM_FAULT_NOPAGE;
4123
4124 pte_unmap_unlock(vmf->pte, vmf->ptl);
4125 }
4126 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
4127 ret = do_read_fault(vmf);
4128 else if (!(vma->vm_flags & VM_SHARED))
4129 ret = do_cow_fault(vmf);
4130 else
4131 ret = do_shared_fault(vmf);
4132
4133 /* preallocated pagetable is unused: free it */
4134 if (vmf->prealloc_pte) {
4135 pte_free(vm_mm, vmf->prealloc_pte);
4136 vmf->prealloc_pte = NULL;
4137 }
4138 return ret;
4139}
4140
4141static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
4142 unsigned long addr, int page_nid,
4143 int *flags)
4144{
4145 get_page(page);
4146
4147 count_vm_numa_event(NUMA_HINT_FAULTS);
4148 if (page_nid == numa_node_id()) {
4149 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
4150 *flags |= TNF_FAULT_LOCAL;
4151 }
4152
4153 return mpol_misplaced(page, vma, addr);
4154}
4155
4156static vm_fault_t do_numa_page(struct vm_fault *vmf)
4157{
4158 struct vm_area_struct *vma = vmf->vma;
4159 struct page *page = NULL;
4160 int page_nid = NUMA_NO_NODE;
4161 int last_cpupid;
4162 int target_nid;
4163 bool migrated = false;
4164 pte_t pte, old_pte;
4165 bool was_writable = pte_savedwrite(vmf->orig_pte);
4166 int flags = 0;
4167
4168 /*
4169 * The "pte" at this point cannot be used safely without
4170 * validation through pte_unmap_same(). It's of NUMA type but
4171 * the pfn may be screwed if the read is non atomic.
4172 */
4173 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
4174 spin_lock(vmf->ptl);
4175 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
4176 pte_unmap_unlock(vmf->pte, vmf->ptl);
4177 goto out;
4178 }
4179
4180 /*
4181 * Make it present again, Depending on how arch implementes non
4182 * accessible ptes, some can allow access by kernel mode.
4183 */
4184 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
4185 pte = pte_modify(old_pte, vma->vm_page_prot);
4186 pte = pte_mkyoung(pte);
4187 if (was_writable)
4188 pte = pte_mkwrite(pte);
4189 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
4190 update_mmu_cache(vma, vmf->address, vmf->pte);
4191
4192 page = vm_normal_page(vma, vmf->address, pte);
4193 if (!page) {
4194 pte_unmap_unlock(vmf->pte, vmf->ptl);
4195 return 0;
4196 }
4197
4198 /* TODO: handle PTE-mapped THP */
4199 if (PageCompound(page)) {
4200 pte_unmap_unlock(vmf->pte, vmf->ptl);
4201 return 0;
4202 }
4203
4204 /*
4205 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
4206 * much anyway since they can be in shared cache state. This misses
4207 * the case where a mapping is writable but the process never writes
4208 * to it but pte_write gets cleared during protection updates and
4209 * pte_dirty has unpredictable behaviour between PTE scan updates,
4210 * background writeback, dirty balancing and application behaviour.
4211 */
4212 if (!pte_write(pte))
4213 flags |= TNF_NO_GROUP;
4214
4215 /*
4216 * Flag if the page is shared between multiple address spaces. This
4217 * is later used when determining whether to group tasks together
4218 */
4219 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
4220 flags |= TNF_SHARED;
4221
4222 last_cpupid = page_cpupid_last(page);
4223 page_nid = page_to_nid(page);
4224 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
4225 &flags);
4226 pte_unmap_unlock(vmf->pte, vmf->ptl);
4227 if (target_nid == NUMA_NO_NODE) {
4228 put_page(page);
4229 goto out;
4230 }
4231
4232 /* Migrate to the requested node */
4233 migrated = migrate_misplaced_page(page, vma, target_nid);
4234 if (migrated) {
4235 page_nid = target_nid;
4236 flags |= TNF_MIGRATED;
4237 } else
4238 flags |= TNF_MIGRATE_FAIL;
4239
4240out:
4241 if (page_nid != NUMA_NO_NODE)
4242 task_numa_fault(last_cpupid, page_nid, 1, flags);
4243 return 0;
4244}
4245
4246static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
4247{
4248 if (vma_is_anonymous(vmf->vma))
4249 return do_huge_pmd_anonymous_page(vmf);
4250 if (vmf->vma->vm_ops->huge_fault)
4251 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4252 return VM_FAULT_FALLBACK;
4253}
4254
4255/* `inline' is required to avoid gcc 4.1.2 build error */
4256static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
4257{
4258 if (vma_is_anonymous(vmf->vma)) {
4259 if (userfaultfd_huge_pmd_wp(vmf->vma, orig_pmd))
4260 return handle_userfault(vmf, VM_UFFD_WP);
4261 return do_huge_pmd_wp_page(vmf, orig_pmd);
4262 }
4263 if (vmf->vma->vm_ops->huge_fault) {
4264 vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
4265
4266 if (!(ret & VM_FAULT_FALLBACK))
4267 return ret;
4268 }
4269
4270 /* COW or write-notify handled on pte level: split pmd. */
4271 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
4272
4273 return VM_FAULT_FALLBACK;
4274}
4275
4276static vm_fault_t create_huge_pud(struct vm_fault *vmf)
4277{
4278#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
4279 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
4280 /* No support for anonymous transparent PUD pages yet */
4281 if (vma_is_anonymous(vmf->vma))
4282 goto split;
4283 if (vmf->vma->vm_ops->huge_fault) {
4284 vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4285
4286 if (!(ret & VM_FAULT_FALLBACK))
4287 return ret;
4288 }
4289split:
4290 /* COW or write-notify not handled on PUD level: split pud.*/
4291 __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
4292#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4293 return VM_FAULT_FALLBACK;
4294}
4295
4296static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
4297{
4298#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4299 /* No support for anonymous transparent PUD pages yet */
4300 if (vma_is_anonymous(vmf->vma))
4301 return VM_FAULT_FALLBACK;
4302 if (vmf->vma->vm_ops->huge_fault)
4303 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
4304#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4305 return VM_FAULT_FALLBACK;
4306}
4307
4308/*
4309 * These routines also need to handle stuff like marking pages dirty
4310 * and/or accessed for architectures that don't do it in hardware (most
4311 * RISC architectures). The early dirtying is also good on the i386.
4312 *
4313 * There is also a hook called "update_mmu_cache()" that architectures
4314 * with external mmu caches can use to update those (ie the Sparc or
4315 * PowerPC hashed page tables that act as extended TLBs).
4316 *
4317 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
4318 * concurrent faults).
4319 *
4320 * The mmap_lock may have been released depending on flags and our return value.
4321 * See filemap_fault() and __lock_page_or_retry().
4322 */
4323static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
4324{
4325 pte_t entry;
4326
4327 if (unlikely(pmd_none(*vmf->pmd))) {
4328 /*
4329 * Leave __pte_alloc() until later: because vm_ops->fault may
4330 * want to allocate huge page, and if we expose page table
4331 * for an instant, it will be difficult to retract from
4332 * concurrent faults and from rmap lookups.
4333 */
4334 vmf->pte = NULL;
4335 } else {
4336 /* See comment in pte_alloc_one_map() */
4337 if (pmd_devmap_trans_unstable(vmf->pmd))
4338 return 0;
4339 /*
4340 * A regular pmd is established and it can't morph into a huge
4341 * pmd from under us anymore at this point because we hold the
4342 * mmap_lock read mode and khugepaged takes it in write mode.
4343 * So now it's safe to run pte_offset_map().
4344 */
4345 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
4346 vmf->orig_pte = *vmf->pte;
4347
4348 /*
4349 * some architectures can have larger ptes than wordsize,
4350 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
4351 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
4352 * accesses. The code below just needs a consistent view
4353 * for the ifs and we later double check anyway with the
4354 * ptl lock held. So here a barrier will do.
4355 */
4356 barrier();
4357 if (pte_none(vmf->orig_pte)) {
4358 pte_unmap(vmf->pte);
4359 vmf->pte = NULL;
4360 }
4361 }
4362
4363 if (!vmf->pte) {
4364 if (vma_is_anonymous(vmf->vma))
4365 return do_anonymous_page(vmf);
4366 else
4367 return do_fault(vmf);
4368 }
4369
4370 if (!pte_present(vmf->orig_pte))
4371 return do_swap_page(vmf);
4372
4373 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
4374 return do_numa_page(vmf);
4375
4376 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
4377 spin_lock(vmf->ptl);
4378 entry = vmf->orig_pte;
4379 if (unlikely(!pte_same(*vmf->pte, entry))) {
4380 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
4381 goto unlock;
4382 }
4383 if (vmf->flags & FAULT_FLAG_WRITE) {
4384 if (!pte_write(entry))
4385 return do_wp_page(vmf);
4386 entry = pte_mkdirty(entry);
4387 }
4388 entry = pte_mkyoung(entry);
4389 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
4390 vmf->flags & FAULT_FLAG_WRITE)) {
4391 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
4392 } else {
4393 /* Skip spurious TLB flush for retried page fault */
4394 if (vmf->flags & FAULT_FLAG_TRIED)
4395 goto unlock;
4396 /*
4397 * This is needed only for protection faults but the arch code
4398 * is not yet telling us if this is a protection fault or not.
4399 * This still avoids useless tlb flushes for .text page faults
4400 * with threads.
4401 */
4402 if (vmf->flags & FAULT_FLAG_WRITE)
4403 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
4404 }
4405unlock:
4406 pte_unmap_unlock(vmf->pte, vmf->ptl);
4407 return 0;
4408}
4409
4410/*
4411 * By the time we get here, we already hold the mm semaphore
4412 *
4413 * The mmap_lock may have been released depending on flags and our
4414 * return value. See filemap_fault() and __lock_page_or_retry().
4415 */
4416static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
4417 unsigned long address, unsigned int flags)
4418{
4419 struct vm_fault vmf = {
4420 .vma = vma,
4421 .address = address & PAGE_MASK,
4422 .flags = flags,
4423 .pgoff = linear_page_index(vma, address),
4424 .gfp_mask = __get_fault_gfp_mask(vma),
4425 };
4426 unsigned int dirty = flags & FAULT_FLAG_WRITE;
4427 struct mm_struct *mm = vma->vm_mm;
4428 pgd_t *pgd;
4429 p4d_t *p4d;
4430 vm_fault_t ret;
4431
4432 pgd = pgd_offset(mm, address);
4433 p4d = p4d_alloc(mm, pgd, address);
4434 if (!p4d)
4435 return VM_FAULT_OOM;
4436
4437 vmf.pud = pud_alloc(mm, p4d, address);
4438 if (!vmf.pud)
4439 return VM_FAULT_OOM;
4440retry_pud:
4441 if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
4442 ret = create_huge_pud(&vmf);
4443 if (!(ret & VM_FAULT_FALLBACK))
4444 return ret;
4445 } else {
4446 pud_t orig_pud = *vmf.pud;
4447
4448 barrier();
4449 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4450
4451 /* NUMA case for anonymous PUDs would go here */
4452
4453 if (dirty && !pud_write(orig_pud)) {
4454 ret = wp_huge_pud(&vmf, orig_pud);
4455 if (!(ret & VM_FAULT_FALLBACK))
4456 return ret;
4457 } else {
4458 huge_pud_set_accessed(&vmf, orig_pud);
4459 return 0;
4460 }
4461 }
4462 }
4463
4464 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4465 if (!vmf.pmd)
4466 return VM_FAULT_OOM;
4467
4468 /* Huge pud page fault raced with pmd_alloc? */
4469 if (pud_trans_unstable(vmf.pud))
4470 goto retry_pud;
4471
4472 if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
4473 ret = create_huge_pmd(&vmf);
4474 if (!(ret & VM_FAULT_FALLBACK))
4475 return ret;
4476 } else {
4477 pmd_t orig_pmd = *vmf.pmd;
4478
4479 barrier();
4480 if (unlikely(is_swap_pmd(orig_pmd))) {
4481 VM_BUG_ON(thp_migration_supported() &&
4482 !is_pmd_migration_entry(orig_pmd));
4483 if (is_pmd_migration_entry(orig_pmd))
4484 pmd_migration_entry_wait(mm, vmf.pmd);
4485 return 0;
4486 }
4487 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
4488 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
4489 return do_huge_pmd_numa_page(&vmf, orig_pmd);
4490
4491 if (dirty && !pmd_write(orig_pmd)) {
4492 ret = wp_huge_pmd(&vmf, orig_pmd);
4493 if (!(ret & VM_FAULT_FALLBACK))
4494 return ret;
4495 } else {
4496 huge_pmd_set_accessed(&vmf, orig_pmd);
4497 return 0;
4498 }
4499 }
4500 }
4501
4502 return handle_pte_fault(&vmf);
4503}
4504
4505/**
4506 * mm_account_fault - Do page fault accountings
4507 *
4508 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
4509 * of perf event counters, but we'll still do the per-task accounting to
4510 * the task who triggered this page fault.
4511 * @address: the faulted address.
4512 * @flags: the fault flags.
4513 * @ret: the fault retcode.
4514 *
4515 * This will take care of most of the page fault accountings. Meanwhile, it
4516 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
4517 * updates. However note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
4518 * still be in per-arch page fault handlers at the entry of page fault.
4519 */
4520static inline void mm_account_fault(struct pt_regs *regs,
4521 unsigned long address, unsigned int flags,
4522 vm_fault_t ret)
4523{
4524 bool major;
4525
4526 /*
4527 * We don't do accounting for some specific faults:
4528 *
4529 * - Unsuccessful faults (e.g. when the address wasn't valid). That
4530 * includes arch_vma_access_permitted() failing before reaching here.
4531 * So this is not a "this many hardware page faults" counter. We
4532 * should use the hw profiling for that.
4533 *
4534 * - Incomplete faults (VM_FAULT_RETRY). They will only be counted
4535 * once they're completed.
4536 */
4537 if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
4538 return;
4539
4540 /*
4541 * We define the fault as a major fault when the final successful fault
4542 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
4543 * handle it immediately previously).
4544 */
4545 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
4546
4547 if (major)
4548 current->maj_flt++;
4549 else
4550 current->min_flt++;
4551
4552 /*
4553 * If the fault is done for GUP, regs will be NULL. We only do the
4554 * accounting for the per thread fault counters who triggered the
4555 * fault, and we skip the perf event updates.
4556 */
4557 if (!regs)
4558 return;
4559
4560 if (major)
4561 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
4562 else
4563 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
4564}
4565
4566/*
4567 * By the time we get here, we already hold the mm semaphore
4568 *
4569 * The mmap_lock may have been released depending on flags and our
4570 * return value. See filemap_fault() and __lock_page_or_retry().
4571 */
4572vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4573 unsigned int flags, struct pt_regs *regs)
4574{
4575 vm_fault_t ret;
4576
4577 __set_current_state(TASK_RUNNING);
4578
4579 count_vm_event(PGFAULT);
4580 count_memcg_event_mm(vma->vm_mm, PGFAULT);
4581
4582 /* do counter updates before entering really critical section. */
4583 check_sync_rss_stat(current);
4584
4585 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4586 flags & FAULT_FLAG_INSTRUCTION,
4587 flags & FAULT_FLAG_REMOTE))
4588 return VM_FAULT_SIGSEGV;
4589
4590 /*
4591 * Enable the memcg OOM handling for faults triggered in user
4592 * space. Kernel faults are handled more gracefully.
4593 */
4594 if (flags & FAULT_FLAG_USER)
4595 mem_cgroup_enter_user_fault();
4596
4597 if (unlikely(is_vm_hugetlb_page(vma)))
4598 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4599 else
4600 ret = __handle_mm_fault(vma, address, flags);
4601
4602 if (flags & FAULT_FLAG_USER) {
4603 mem_cgroup_exit_user_fault();
4604 /*
4605 * The task may have entered a memcg OOM situation but
4606 * if the allocation error was handled gracefully (no
4607 * VM_FAULT_OOM), there is no need to kill anything.
4608 * Just clean up the OOM state peacefully.
4609 */
4610 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4611 mem_cgroup_oom_synchronize(false);
4612 }
4613
4614 mm_account_fault(regs, address, flags, ret);
4615
4616 return ret;
4617}
4618EXPORT_SYMBOL_GPL(handle_mm_fault);
4619
4620#ifndef __PAGETABLE_P4D_FOLDED
4621/*
4622 * Allocate p4d page table.
4623 * We've already handled the fast-path in-line.
4624 */
4625int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4626{
4627 p4d_t *new = p4d_alloc_one(mm, address);
4628 if (!new)
4629 return -ENOMEM;
4630
4631 smp_wmb(); /* See comment in __pte_alloc */
4632
4633 spin_lock(&mm->page_table_lock);
4634 if (pgd_present(*pgd)) /* Another has populated it */
4635 p4d_free(mm, new);
4636 else
4637 pgd_populate(mm, pgd, new);
4638 spin_unlock(&mm->page_table_lock);
4639 return 0;
4640}
4641#endif /* __PAGETABLE_P4D_FOLDED */
4642
4643#ifndef __PAGETABLE_PUD_FOLDED
4644/*
4645 * Allocate page upper directory.
4646 * We've already handled the fast-path in-line.
4647 */
4648int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4649{
4650 pud_t *new = pud_alloc_one(mm, address);
4651 if (!new)
4652 return -ENOMEM;
4653
4654 smp_wmb(); /* See comment in __pte_alloc */
4655
4656 spin_lock(&mm->page_table_lock);
4657 if (!p4d_present(*p4d)) {
4658 mm_inc_nr_puds(mm);
4659 p4d_populate(mm, p4d, new);
4660 } else /* Another has populated it */
4661 pud_free(mm, new);
4662 spin_unlock(&mm->page_table_lock);
4663 return 0;
4664}
4665#endif /* __PAGETABLE_PUD_FOLDED */
4666
4667#ifndef __PAGETABLE_PMD_FOLDED
4668/*
4669 * Allocate page middle directory.
4670 * We've already handled the fast-path in-line.
4671 */
4672int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4673{
4674 spinlock_t *ptl;
4675 pmd_t *new = pmd_alloc_one(mm, address);
4676 if (!new)
4677 return -ENOMEM;
4678
4679 smp_wmb(); /* See comment in __pte_alloc */
4680
4681 ptl = pud_lock(mm, pud);
4682 if (!pud_present(*pud)) {
4683 mm_inc_nr_pmds(mm);
4684 pud_populate(mm, pud, new);
4685 } else /* Another has populated it */
4686 pmd_free(mm, new);
4687 spin_unlock(ptl);
4688 return 0;
4689}
4690#endif /* __PAGETABLE_PMD_FOLDED */
4691
4692static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4693 struct mmu_notifier_range *range,
4694 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4695{
4696 pgd_t *pgd;
4697 p4d_t *p4d;
4698 pud_t *pud;
4699 pmd_t *pmd;
4700 pte_t *ptep;
4701
4702 pgd = pgd_offset(mm, address);
4703 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4704 goto out;
4705
4706 p4d = p4d_offset(pgd, address);
4707 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4708 goto out;
4709
4710 pud = pud_offset(p4d, address);
4711 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4712 goto out;
4713
4714 pmd = pmd_offset(pud, address);
4715 VM_BUG_ON(pmd_trans_huge(*pmd));
4716
4717 if (pmd_huge(*pmd)) {
4718 if (!pmdpp)
4719 goto out;
4720
4721 if (range) {
4722 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0,
4723 NULL, mm, address & PMD_MASK,
4724 (address & PMD_MASK) + PMD_SIZE);
4725 mmu_notifier_invalidate_range_start(range);
4726 }
4727 *ptlp = pmd_lock(mm, pmd);
4728 if (pmd_huge(*pmd)) {
4729 *pmdpp = pmd;
4730 return 0;
4731 }
4732 spin_unlock(*ptlp);
4733 if (range)
4734 mmu_notifier_invalidate_range_end(range);
4735 }
4736
4737 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4738 goto out;
4739
4740 if (range) {
4741 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
4742 address & PAGE_MASK,
4743 (address & PAGE_MASK) + PAGE_SIZE);
4744 mmu_notifier_invalidate_range_start(range);
4745 }
4746 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4747 if (!pte_present(*ptep))
4748 goto unlock;
4749 *ptepp = ptep;
4750 return 0;
4751unlock:
4752 pte_unmap_unlock(ptep, *ptlp);
4753 if (range)
4754 mmu_notifier_invalidate_range_end(range);
4755out:
4756 return -EINVAL;
4757}
4758
4759static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4760 pte_t **ptepp, spinlock_t **ptlp)
4761{
4762 int res;
4763
4764 /* (void) is needed to make gcc happy */
4765 (void) __cond_lock(*ptlp,
4766 !(res = __follow_pte_pmd(mm, address, NULL,
4767 ptepp, NULL, ptlp)));
4768 return res;
4769}
4770
4771int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4772 struct mmu_notifier_range *range,
4773 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4774{
4775 int res;
4776
4777 /* (void) is needed to make gcc happy */
4778 (void) __cond_lock(*ptlp,
4779 !(res = __follow_pte_pmd(mm, address, range,
4780 ptepp, pmdpp, ptlp)));
4781 return res;
4782}
4783EXPORT_SYMBOL(follow_pte_pmd);
4784
4785/**
4786 * follow_pfn - look up PFN at a user virtual address
4787 * @vma: memory mapping
4788 * @address: user virtual address
4789 * @pfn: location to store found PFN
4790 *
4791 * Only IO mappings and raw PFN mappings are allowed.
4792 *
4793 * Return: zero and the pfn at @pfn on success, -ve otherwise.
4794 */
4795int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4796 unsigned long *pfn)
4797{
4798 int ret = -EINVAL;
4799 spinlock_t *ptl;
4800 pte_t *ptep;
4801
4802 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4803 return ret;
4804
4805 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4806 if (ret)
4807 return ret;
4808 *pfn = pte_pfn(*ptep);
4809 pte_unmap_unlock(ptep, ptl);
4810 return 0;
4811}
4812EXPORT_SYMBOL(follow_pfn);
4813
4814#ifdef CONFIG_HAVE_IOREMAP_PROT
4815int follow_phys(struct vm_area_struct *vma,
4816 unsigned long address, unsigned int flags,
4817 unsigned long *prot, resource_size_t *phys)
4818{
4819 int ret = -EINVAL;
4820 pte_t *ptep, pte;
4821 spinlock_t *ptl;
4822
4823 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4824 goto out;
4825
4826 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4827 goto out;
4828 pte = *ptep;
4829
4830 if ((flags & FOLL_WRITE) && !pte_write(pte))
4831 goto unlock;
4832
4833 *prot = pgprot_val(pte_pgprot(pte));
4834 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4835
4836 ret = 0;
4837unlock:
4838 pte_unmap_unlock(ptep, ptl);
4839out:
4840 return ret;
4841}
4842
4843int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4844 void *buf, int len, int write)
4845{
4846 resource_size_t phys_addr;
4847 unsigned long prot = 0;
4848 void __iomem *maddr;
4849 int offset = addr & (PAGE_SIZE-1);
4850
4851 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4852 return -EINVAL;
4853
4854 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4855 if (!maddr)
4856 return -ENOMEM;
4857
4858 if (write)
4859 memcpy_toio(maddr + offset, buf, len);
4860 else
4861 memcpy_fromio(buf, maddr + offset, len);
4862 iounmap(maddr);
4863
4864 return len;
4865}
4866EXPORT_SYMBOL_GPL(generic_access_phys);
4867#endif
4868
4869/*
4870 * Access another process' address space as given in mm. If non-NULL, use the
4871 * given task for page fault accounting.
4872 */
4873int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4874 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4875{
4876 struct vm_area_struct *vma;
4877 void *old_buf = buf;
4878 int write = gup_flags & FOLL_WRITE;
4879
4880 if (mmap_read_lock_killable(mm))
4881 return 0;
4882
4883 /* ignore errors, just check how much was successfully transferred */
4884 while (len) {
4885 int bytes, ret, offset;
4886 void *maddr;
4887 struct page *page = NULL;
4888
4889 ret = get_user_pages_remote(mm, addr, 1,
4890 gup_flags, &page, &vma, NULL);
4891 if (ret <= 0) {
4892#ifndef CONFIG_HAVE_IOREMAP_PROT
4893 break;
4894#else
4895 /*
4896 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4897 * we can access using slightly different code.
4898 */
4899 vma = find_vma(mm, addr);
4900 if (!vma || vma->vm_start > addr)
4901 break;
4902 if (vma->vm_ops && vma->vm_ops->access)
4903 ret = vma->vm_ops->access(vma, addr, buf,
4904 len, write);
4905 if (ret <= 0)
4906 break;
4907 bytes = ret;
4908#endif
4909 } else {
4910 bytes = len;
4911 offset = addr & (PAGE_SIZE-1);
4912 if (bytes > PAGE_SIZE-offset)
4913 bytes = PAGE_SIZE-offset;
4914
4915 maddr = kmap(page);
4916 if (write) {
4917 copy_to_user_page(vma, page, addr,
4918 maddr + offset, buf, bytes);
4919 set_page_dirty_lock(page);
4920 } else {
4921 copy_from_user_page(vma, page, addr,
4922 buf, maddr + offset, bytes);
4923 }
4924 kunmap(page);
4925 put_page(page);
4926 }
4927 len -= bytes;
4928 buf += bytes;
4929 addr += bytes;
4930 }
4931 mmap_read_unlock(mm);
4932
4933 return buf - old_buf;
4934}
4935
4936/**
4937 * access_remote_vm - access another process' address space
4938 * @mm: the mm_struct of the target address space
4939 * @addr: start address to access
4940 * @buf: source or destination buffer
4941 * @len: number of bytes to transfer
4942 * @gup_flags: flags modifying lookup behaviour
4943 *
4944 * The caller must hold a reference on @mm.
4945 *
4946 * Return: number of bytes copied from source to destination.
4947 */
4948int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4949 void *buf, int len, unsigned int gup_flags)
4950{
4951 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4952}
4953
4954/*
4955 * Access another process' address space.
4956 * Source/target buffer must be kernel space,
4957 * Do not walk the page table directly, use get_user_pages
4958 */
4959int access_process_vm(struct task_struct *tsk, unsigned long addr,
4960 void *buf, int len, unsigned int gup_flags)
4961{
4962 struct mm_struct *mm;
4963 int ret;
4964
4965 mm = get_task_mm(tsk);
4966 if (!mm)
4967 return 0;
4968
4969 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4970
4971 mmput(mm);
4972
4973 return ret;
4974}
4975EXPORT_SYMBOL_GPL(access_process_vm);
4976
4977/*
4978 * Print the name of a VMA.
4979 */
4980void print_vma_addr(char *prefix, unsigned long ip)
4981{
4982 struct mm_struct *mm = current->mm;
4983 struct vm_area_struct *vma;
4984
4985 /*
4986 * we might be running from an atomic context so we cannot sleep
4987 */
4988 if (!mmap_read_trylock(mm))
4989 return;
4990
4991 vma = find_vma(mm, ip);
4992 if (vma && vma->vm_file) {
4993 struct file *f = vma->vm_file;
4994 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4995 if (buf) {
4996 char *p;
4997
4998 p = file_path(f, buf, PAGE_SIZE);
4999 if (IS_ERR(p))
5000 p = "?";
5001 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
5002 vma->vm_start,
5003 vma->vm_end - vma->vm_start);
5004 free_page((unsigned long)buf);
5005 }
5006 }
5007 mmap_read_unlock(mm);
5008}
5009
5010#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5011void __might_fault(const char *file, int line)
5012{
5013 /*
5014 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
5015 * holding the mmap_lock, this is safe because kernel memory doesn't
5016 * get paged out, therefore we'll never actually fault, and the
5017 * below annotations will generate false positives.
5018 */
5019 if (uaccess_kernel())
5020 return;
5021 if (pagefault_disabled())
5022 return;
5023 __might_sleep(file, line, 0);
5024#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
5025 if (current->mm)
5026 might_lock_read(¤t->mm->mmap_lock);
5027#endif
5028}
5029EXPORT_SYMBOL(__might_fault);
5030#endif
5031
5032#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
5033/*
5034 * Process all subpages of the specified huge page with the specified
5035 * operation. The target subpage will be processed last to keep its
5036 * cache lines hot.
5037 */
5038static inline void process_huge_page(
5039 unsigned long addr_hint, unsigned int pages_per_huge_page,
5040 void (*process_subpage)(unsigned long addr, int idx, void *arg),
5041 void *arg)
5042{
5043 int i, n, base, l;
5044 unsigned long addr = addr_hint &
5045 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5046
5047 /* Process target subpage last to keep its cache lines hot */
5048 might_sleep();
5049 n = (addr_hint - addr) / PAGE_SIZE;
5050 if (2 * n <= pages_per_huge_page) {
5051 /* If target subpage in first half of huge page */
5052 base = 0;
5053 l = n;
5054 /* Process subpages at the end of huge page */
5055 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
5056 cond_resched();
5057 process_subpage(addr + i * PAGE_SIZE, i, arg);
5058 }
5059 } else {
5060 /* If target subpage in second half of huge page */
5061 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
5062 l = pages_per_huge_page - n;
5063 /* Process subpages at the begin of huge page */
5064 for (i = 0; i < base; i++) {
5065 cond_resched();
5066 process_subpage(addr + i * PAGE_SIZE, i, arg);
5067 }
5068 }
5069 /*
5070 * Process remaining subpages in left-right-left-right pattern
5071 * towards the target subpage
5072 */
5073 for (i = 0; i < l; i++) {
5074 int left_idx = base + i;
5075 int right_idx = base + 2 * l - 1 - i;
5076
5077 cond_resched();
5078 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
5079 cond_resched();
5080 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
5081 }
5082}
5083
5084static void clear_gigantic_page(struct page *page,
5085 unsigned long addr,
5086 unsigned int pages_per_huge_page)
5087{
5088 int i;
5089 struct page *p = page;
5090
5091 might_sleep();
5092 for (i = 0; i < pages_per_huge_page;
5093 i++, p = mem_map_next(p, page, i)) {
5094 cond_resched();
5095 clear_user_highpage(p, addr + i * PAGE_SIZE);
5096 }
5097}
5098
5099static void clear_subpage(unsigned long addr, int idx, void *arg)
5100{
5101 struct page *page = arg;
5102
5103 clear_user_highpage(page + idx, addr);
5104}
5105
5106void clear_huge_page(struct page *page,
5107 unsigned long addr_hint, unsigned int pages_per_huge_page)
5108{
5109 unsigned long addr = addr_hint &
5110 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5111
5112 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5113 clear_gigantic_page(page, addr, pages_per_huge_page);
5114 return;
5115 }
5116
5117 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
5118}
5119
5120static void copy_user_gigantic_page(struct page *dst, struct page *src,
5121 unsigned long addr,
5122 struct vm_area_struct *vma,
5123 unsigned int pages_per_huge_page)
5124{
5125 int i;
5126 struct page *dst_base = dst;
5127 struct page *src_base = src;
5128
5129 for (i = 0; i < pages_per_huge_page; ) {
5130 cond_resched();
5131 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
5132
5133 i++;
5134 dst = mem_map_next(dst, dst_base, i);
5135 src = mem_map_next(src, src_base, i);
5136 }
5137}
5138
5139struct copy_subpage_arg {
5140 struct page *dst;
5141 struct page *src;
5142 struct vm_area_struct *vma;
5143};
5144
5145static void copy_subpage(unsigned long addr, int idx, void *arg)
5146{
5147 struct copy_subpage_arg *copy_arg = arg;
5148
5149 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
5150 addr, copy_arg->vma);
5151}
5152
5153void copy_user_huge_page(struct page *dst, struct page *src,
5154 unsigned long addr_hint, struct vm_area_struct *vma,
5155 unsigned int pages_per_huge_page)
5156{
5157 unsigned long addr = addr_hint &
5158 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
5159 struct copy_subpage_arg arg = {
5160 .dst = dst,
5161 .src = src,
5162 .vma = vma,
5163 };
5164
5165 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
5166 copy_user_gigantic_page(dst, src, addr, vma,
5167 pages_per_huge_page);
5168 return;
5169 }
5170
5171 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
5172}
5173
5174long copy_huge_page_from_user(struct page *dst_page,
5175 const void __user *usr_src,
5176 unsigned int pages_per_huge_page,
5177 bool allow_pagefault)
5178{
5179 void *src = (void *)usr_src;
5180 void *page_kaddr;
5181 unsigned long i, rc = 0;
5182 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
5183
5184 for (i = 0; i < pages_per_huge_page; i++) {
5185 if (allow_pagefault)
5186 page_kaddr = kmap(dst_page + i);
5187 else
5188 page_kaddr = kmap_atomic(dst_page + i);
5189 rc = copy_from_user(page_kaddr,
5190 (const void __user *)(src + i * PAGE_SIZE),
5191 PAGE_SIZE);
5192 if (allow_pagefault)
5193 kunmap(dst_page + i);
5194 else
5195 kunmap_atomic(page_kaddr);
5196
5197 ret_val -= (PAGE_SIZE - rc);
5198 if (rc)
5199 break;
5200
5201 cond_resched();
5202 }
5203 return ret_val;
5204}
5205#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
5206
5207#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
5208
5209static struct kmem_cache *page_ptl_cachep;
5210
5211void __init ptlock_cache_init(void)
5212{
5213 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
5214 SLAB_PANIC, NULL);
5215}
5216
5217bool ptlock_alloc(struct page *page)
5218{
5219 spinlock_t *ptl;
5220
5221 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
5222 if (!ptl)
5223 return false;
5224 page->ptl = ptl;
5225 return true;
5226}
5227
5228void ptlock_free(struct page *page)
5229{
5230 kmem_cache_free(page_ptl_cachep, page->ptl);
5231}
5232#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/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/dma-debug.h>
69#include <linux/debugfs.h>
70#include <linux/userfaultfd_k.h>
71#include <linux/dax.h>
72#include <linux/oom.h>
73#include <linux/numa.h>
74
75#include <asm/io.h>
76#include <asm/mmu_context.h>
77#include <asm/pgalloc.h>
78#include <linux/uaccess.h>
79#include <asm/tlb.h>
80#include <asm/tlbflush.h>
81#include <asm/pgtable.h>
82
83#include "internal.h"
84
85#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
86#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
87#endif
88
89#ifndef CONFIG_NEED_MULTIPLE_NODES
90/* use the per-pgdat data instead for discontigmem - mbligh */
91unsigned long max_mapnr;
92EXPORT_SYMBOL(max_mapnr);
93
94struct page *mem_map;
95EXPORT_SYMBOL(mem_map);
96#endif
97
98/*
99 * A number of key systems in x86 including ioremap() rely on the assumption
100 * that high_memory defines the upper bound on direct map memory, then end
101 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
102 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
103 * and ZONE_HIGHMEM.
104 */
105void *high_memory;
106EXPORT_SYMBOL(high_memory);
107
108/*
109 * Randomize the address space (stacks, mmaps, brk, etc.).
110 *
111 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
112 * as ancient (libc5 based) binaries can segfault. )
113 */
114int randomize_va_space __read_mostly =
115#ifdef CONFIG_COMPAT_BRK
116 1;
117#else
118 2;
119#endif
120
121static int __init disable_randmaps(char *s)
122{
123 randomize_va_space = 0;
124 return 1;
125}
126__setup("norandmaps", disable_randmaps);
127
128unsigned long zero_pfn __read_mostly;
129EXPORT_SYMBOL(zero_pfn);
130
131unsigned long highest_memmap_pfn __read_mostly;
132
133/*
134 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
135 */
136static int __init init_zero_pfn(void)
137{
138 zero_pfn = page_to_pfn(ZERO_PAGE(0));
139 return 0;
140}
141core_initcall(init_zero_pfn);
142
143
144#if defined(SPLIT_RSS_COUNTING)
145
146void sync_mm_rss(struct mm_struct *mm)
147{
148 int i;
149
150 for (i = 0; i < NR_MM_COUNTERS; i++) {
151 if (current->rss_stat.count[i]) {
152 add_mm_counter(mm, i, current->rss_stat.count[i]);
153 current->rss_stat.count[i] = 0;
154 }
155 }
156 current->rss_stat.events = 0;
157}
158
159static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
160{
161 struct task_struct *task = current;
162
163 if (likely(task->mm == mm))
164 task->rss_stat.count[member] += val;
165 else
166 add_mm_counter(mm, member, val);
167}
168#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
169#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
170
171/* sync counter once per 64 page faults */
172#define TASK_RSS_EVENTS_THRESH (64)
173static void check_sync_rss_stat(struct task_struct *task)
174{
175 if (unlikely(task != current))
176 return;
177 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
178 sync_mm_rss(task->mm);
179}
180#else /* SPLIT_RSS_COUNTING */
181
182#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
183#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
184
185static void check_sync_rss_stat(struct task_struct *task)
186{
187}
188
189#endif /* SPLIT_RSS_COUNTING */
190
191/*
192 * Note: this doesn't free the actual pages themselves. That
193 * has been handled earlier when unmapping all the memory regions.
194 */
195static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
196 unsigned long addr)
197{
198 pgtable_t token = pmd_pgtable(*pmd);
199 pmd_clear(pmd);
200 pte_free_tlb(tlb, token, addr);
201 mm_dec_nr_ptes(tlb->mm);
202}
203
204static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
205 unsigned long addr, unsigned long end,
206 unsigned long floor, unsigned long ceiling)
207{
208 pmd_t *pmd;
209 unsigned long next;
210 unsigned long start;
211
212 start = addr;
213 pmd = pmd_offset(pud, addr);
214 do {
215 next = pmd_addr_end(addr, end);
216 if (pmd_none_or_clear_bad(pmd))
217 continue;
218 free_pte_range(tlb, pmd, addr);
219 } while (pmd++, addr = next, addr != end);
220
221 start &= PUD_MASK;
222 if (start < floor)
223 return;
224 if (ceiling) {
225 ceiling &= PUD_MASK;
226 if (!ceiling)
227 return;
228 }
229 if (end - 1 > ceiling - 1)
230 return;
231
232 pmd = pmd_offset(pud, start);
233 pud_clear(pud);
234 pmd_free_tlb(tlb, pmd, start);
235 mm_dec_nr_pmds(tlb->mm);
236}
237
238static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
239 unsigned long addr, unsigned long end,
240 unsigned long floor, unsigned long ceiling)
241{
242 pud_t *pud;
243 unsigned long next;
244 unsigned long start;
245
246 start = addr;
247 pud = pud_offset(p4d, addr);
248 do {
249 next = pud_addr_end(addr, end);
250 if (pud_none_or_clear_bad(pud))
251 continue;
252 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
253 } while (pud++, addr = next, addr != end);
254
255 start &= P4D_MASK;
256 if (start < floor)
257 return;
258 if (ceiling) {
259 ceiling &= P4D_MASK;
260 if (!ceiling)
261 return;
262 }
263 if (end - 1 > ceiling - 1)
264 return;
265
266 pud = pud_offset(p4d, start);
267 p4d_clear(p4d);
268 pud_free_tlb(tlb, pud, start);
269 mm_dec_nr_puds(tlb->mm);
270}
271
272static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
273 unsigned long addr, unsigned long end,
274 unsigned long floor, unsigned long ceiling)
275{
276 p4d_t *p4d;
277 unsigned long next;
278 unsigned long start;
279
280 start = addr;
281 p4d = p4d_offset(pgd, addr);
282 do {
283 next = p4d_addr_end(addr, end);
284 if (p4d_none_or_clear_bad(p4d))
285 continue;
286 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
287 } while (p4d++, addr = next, addr != end);
288
289 start &= PGDIR_MASK;
290 if (start < floor)
291 return;
292 if (ceiling) {
293 ceiling &= PGDIR_MASK;
294 if (!ceiling)
295 return;
296 }
297 if (end - 1 > ceiling - 1)
298 return;
299
300 p4d = p4d_offset(pgd, start);
301 pgd_clear(pgd);
302 p4d_free_tlb(tlb, p4d, start);
303}
304
305/*
306 * This function frees user-level page tables of a process.
307 */
308void free_pgd_range(struct mmu_gather *tlb,
309 unsigned long addr, unsigned long end,
310 unsigned long floor, unsigned long ceiling)
311{
312 pgd_t *pgd;
313 unsigned long next;
314
315 /*
316 * The next few lines have given us lots of grief...
317 *
318 * Why are we testing PMD* at this top level? Because often
319 * there will be no work to do at all, and we'd prefer not to
320 * go all the way down to the bottom just to discover that.
321 *
322 * Why all these "- 1"s? Because 0 represents both the bottom
323 * of the address space and the top of it (using -1 for the
324 * top wouldn't help much: the masks would do the wrong thing).
325 * The rule is that addr 0 and floor 0 refer to the bottom of
326 * the address space, but end 0 and ceiling 0 refer to the top
327 * Comparisons need to use "end - 1" and "ceiling - 1" (though
328 * that end 0 case should be mythical).
329 *
330 * Wherever addr is brought up or ceiling brought down, we must
331 * be careful to reject "the opposite 0" before it confuses the
332 * subsequent tests. But what about where end is brought down
333 * by PMD_SIZE below? no, end can't go down to 0 there.
334 *
335 * Whereas we round start (addr) and ceiling down, by different
336 * masks at different levels, in order to test whether a table
337 * now has no other vmas using it, so can be freed, we don't
338 * bother to round floor or end up - the tests don't need that.
339 */
340
341 addr &= PMD_MASK;
342 if (addr < floor) {
343 addr += PMD_SIZE;
344 if (!addr)
345 return;
346 }
347 if (ceiling) {
348 ceiling &= PMD_MASK;
349 if (!ceiling)
350 return;
351 }
352 if (end - 1 > ceiling - 1)
353 end -= PMD_SIZE;
354 if (addr > end - 1)
355 return;
356 /*
357 * We add page table cache pages with PAGE_SIZE,
358 * (see pte_free_tlb()), flush the tlb if we need
359 */
360 tlb_change_page_size(tlb, PAGE_SIZE);
361 pgd = pgd_offset(tlb->mm, addr);
362 do {
363 next = pgd_addr_end(addr, end);
364 if (pgd_none_or_clear_bad(pgd))
365 continue;
366 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
367 } while (pgd++, addr = next, addr != end);
368}
369
370void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
371 unsigned long floor, unsigned long ceiling)
372{
373 while (vma) {
374 struct vm_area_struct *next = vma->vm_next;
375 unsigned long addr = vma->vm_start;
376
377 /*
378 * Hide vma from rmap and truncate_pagecache before freeing
379 * pgtables
380 */
381 unlink_anon_vmas(vma);
382 unlink_file_vma(vma);
383
384 if (is_vm_hugetlb_page(vma)) {
385 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
386 floor, next ? next->vm_start : ceiling);
387 } else {
388 /*
389 * Optimization: gather nearby vmas into one call down
390 */
391 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
392 && !is_vm_hugetlb_page(next)) {
393 vma = next;
394 next = vma->vm_next;
395 unlink_anon_vmas(vma);
396 unlink_file_vma(vma);
397 }
398 free_pgd_range(tlb, addr, vma->vm_end,
399 floor, next ? next->vm_start : ceiling);
400 }
401 vma = next;
402 }
403}
404
405int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
406{
407 spinlock_t *ptl;
408 pgtable_t new = pte_alloc_one(mm);
409 if (!new)
410 return -ENOMEM;
411
412 /*
413 * Ensure all pte setup (eg. pte page lock and page clearing) are
414 * visible before the pte is made visible to other CPUs by being
415 * put into page tables.
416 *
417 * The other side of the story is the pointer chasing in the page
418 * table walking code (when walking the page table without locking;
419 * ie. most of the time). Fortunately, these data accesses consist
420 * of a chain of data-dependent loads, meaning most CPUs (alpha
421 * being the notable exception) will already guarantee loads are
422 * seen in-order. See the alpha page table accessors for the
423 * smp_read_barrier_depends() barriers in page table walking code.
424 */
425 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
426
427 ptl = pmd_lock(mm, pmd);
428 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
429 mm_inc_nr_ptes(mm);
430 pmd_populate(mm, pmd, new);
431 new = NULL;
432 }
433 spin_unlock(ptl);
434 if (new)
435 pte_free(mm, new);
436 return 0;
437}
438
439int __pte_alloc_kernel(pmd_t *pmd)
440{
441 pte_t *new = pte_alloc_one_kernel(&init_mm);
442 if (!new)
443 return -ENOMEM;
444
445 smp_wmb(); /* See comment in __pte_alloc */
446
447 spin_lock(&init_mm.page_table_lock);
448 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
449 pmd_populate_kernel(&init_mm, pmd, new);
450 new = NULL;
451 }
452 spin_unlock(&init_mm.page_table_lock);
453 if (new)
454 pte_free_kernel(&init_mm, new);
455 return 0;
456}
457
458static inline void init_rss_vec(int *rss)
459{
460 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
461}
462
463static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
464{
465 int i;
466
467 if (current->mm == mm)
468 sync_mm_rss(mm);
469 for (i = 0; i < NR_MM_COUNTERS; i++)
470 if (rss[i])
471 add_mm_counter(mm, i, rss[i]);
472}
473
474/*
475 * This function is called to print an error when a bad pte
476 * is found. For example, we might have a PFN-mapped pte in
477 * a region that doesn't allow it.
478 *
479 * The calling function must still handle the error.
480 */
481static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
482 pte_t pte, struct page *page)
483{
484 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
485 p4d_t *p4d = p4d_offset(pgd, addr);
486 pud_t *pud = pud_offset(p4d, addr);
487 pmd_t *pmd = pmd_offset(pud, addr);
488 struct address_space *mapping;
489 pgoff_t index;
490 static unsigned long resume;
491 static unsigned long nr_shown;
492 static unsigned long nr_unshown;
493
494 /*
495 * Allow a burst of 60 reports, then keep quiet for that minute;
496 * or allow a steady drip of one report per second.
497 */
498 if (nr_shown == 60) {
499 if (time_before(jiffies, resume)) {
500 nr_unshown++;
501 return;
502 }
503 if (nr_unshown) {
504 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
505 nr_unshown);
506 nr_unshown = 0;
507 }
508 nr_shown = 0;
509 }
510 if (nr_shown++ == 0)
511 resume = jiffies + 60 * HZ;
512
513 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
514 index = linear_page_index(vma, addr);
515
516 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
517 current->comm,
518 (long long)pte_val(pte), (long long)pmd_val(*pmd));
519 if (page)
520 dump_page(page, "bad pte");
521 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
522 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
523 pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
524 vma->vm_file,
525 vma->vm_ops ? vma->vm_ops->fault : NULL,
526 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
527 mapping ? mapping->a_ops->readpage : NULL);
528 dump_stack();
529 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
530}
531
532/*
533 * vm_normal_page -- This function gets the "struct page" associated with a pte.
534 *
535 * "Special" mappings do not wish to be associated with a "struct page" (either
536 * it doesn't exist, or it exists but they don't want to touch it). In this
537 * case, NULL is returned here. "Normal" mappings do have a struct page.
538 *
539 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
540 * pte bit, in which case this function is trivial. Secondly, an architecture
541 * may not have a spare pte bit, which requires a more complicated scheme,
542 * described below.
543 *
544 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
545 * special mapping (even if there are underlying and valid "struct pages").
546 * COWed pages of a VM_PFNMAP are always normal.
547 *
548 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
549 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
550 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
551 * mapping will always honor the rule
552 *
553 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
554 *
555 * And for normal mappings this is false.
556 *
557 * This restricts such mappings to be a linear translation from virtual address
558 * to pfn. To get around this restriction, we allow arbitrary mappings so long
559 * as the vma is not a COW mapping; in that case, we know that all ptes are
560 * special (because none can have been COWed).
561 *
562 *
563 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
564 *
565 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
566 * page" backing, however the difference is that _all_ pages with a struct
567 * page (that is, those where pfn_valid is true) are refcounted and considered
568 * normal pages by the VM. The disadvantage is that pages are refcounted
569 * (which can be slower and simply not an option for some PFNMAP users). The
570 * advantage is that we don't have to follow the strict linearity rule of
571 * PFNMAP mappings in order to support COWable mappings.
572 *
573 */
574struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
575 pte_t pte)
576{
577 unsigned long pfn = pte_pfn(pte);
578
579 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
580 if (likely(!pte_special(pte)))
581 goto check_pfn;
582 if (vma->vm_ops && vma->vm_ops->find_special_page)
583 return vma->vm_ops->find_special_page(vma, addr);
584 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
585 return NULL;
586 if (is_zero_pfn(pfn))
587 return NULL;
588 if (pte_devmap(pte))
589 return NULL;
590
591 print_bad_pte(vma, addr, pte, NULL);
592 return NULL;
593 }
594
595 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
596
597 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
598 if (vma->vm_flags & VM_MIXEDMAP) {
599 if (!pfn_valid(pfn))
600 return NULL;
601 goto out;
602 } else {
603 unsigned long off;
604 off = (addr - vma->vm_start) >> PAGE_SHIFT;
605 if (pfn == vma->vm_pgoff + off)
606 return NULL;
607 if (!is_cow_mapping(vma->vm_flags))
608 return NULL;
609 }
610 }
611
612 if (is_zero_pfn(pfn))
613 return NULL;
614
615check_pfn:
616 if (unlikely(pfn > highest_memmap_pfn)) {
617 print_bad_pte(vma, addr, pte, NULL);
618 return NULL;
619 }
620
621 /*
622 * NOTE! We still have PageReserved() pages in the page tables.
623 * eg. VDSO mappings can cause them to exist.
624 */
625out:
626 return pfn_to_page(pfn);
627}
628
629#ifdef CONFIG_TRANSPARENT_HUGEPAGE
630struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
631 pmd_t pmd)
632{
633 unsigned long pfn = pmd_pfn(pmd);
634
635 /*
636 * There is no pmd_special() but there may be special pmds, e.g.
637 * in a direct-access (dax) mapping, so let's just replicate the
638 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
639 */
640 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
641 if (vma->vm_flags & VM_MIXEDMAP) {
642 if (!pfn_valid(pfn))
643 return NULL;
644 goto out;
645 } else {
646 unsigned long off;
647 off = (addr - vma->vm_start) >> PAGE_SHIFT;
648 if (pfn == vma->vm_pgoff + off)
649 return NULL;
650 if (!is_cow_mapping(vma->vm_flags))
651 return NULL;
652 }
653 }
654
655 if (pmd_devmap(pmd))
656 return NULL;
657 if (is_zero_pfn(pfn))
658 return NULL;
659 if (unlikely(pfn > highest_memmap_pfn))
660 return NULL;
661
662 /*
663 * NOTE! We still have PageReserved() pages in the page tables.
664 * eg. VDSO mappings can cause them to exist.
665 */
666out:
667 return pfn_to_page(pfn);
668}
669#endif
670
671/*
672 * copy one vm_area from one task to the other. Assumes the page tables
673 * already present in the new task to be cleared in the whole range
674 * covered by this vma.
675 */
676
677static inline unsigned long
678copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
679 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
680 unsigned long addr, int *rss)
681{
682 unsigned long vm_flags = vma->vm_flags;
683 pte_t pte = *src_pte;
684 struct page *page;
685
686 /* pte contains position in swap or file, so copy. */
687 if (unlikely(!pte_present(pte))) {
688 swp_entry_t entry = pte_to_swp_entry(pte);
689
690 if (likely(!non_swap_entry(entry))) {
691 if (swap_duplicate(entry) < 0)
692 return entry.val;
693
694 /* make sure dst_mm is on swapoff's mmlist. */
695 if (unlikely(list_empty(&dst_mm->mmlist))) {
696 spin_lock(&mmlist_lock);
697 if (list_empty(&dst_mm->mmlist))
698 list_add(&dst_mm->mmlist,
699 &src_mm->mmlist);
700 spin_unlock(&mmlist_lock);
701 }
702 rss[MM_SWAPENTS]++;
703 } else if (is_migration_entry(entry)) {
704 page = migration_entry_to_page(entry);
705
706 rss[mm_counter(page)]++;
707
708 if (is_write_migration_entry(entry) &&
709 is_cow_mapping(vm_flags)) {
710 /*
711 * COW mappings require pages in both
712 * parent and child to be set to read.
713 */
714 make_migration_entry_read(&entry);
715 pte = swp_entry_to_pte(entry);
716 if (pte_swp_soft_dirty(*src_pte))
717 pte = pte_swp_mksoft_dirty(pte);
718 set_pte_at(src_mm, addr, src_pte, pte);
719 }
720 } else if (is_device_private_entry(entry)) {
721 page = device_private_entry_to_page(entry);
722
723 /*
724 * Update rss count even for unaddressable pages, as
725 * they should treated just like normal pages in this
726 * respect.
727 *
728 * We will likely want to have some new rss counters
729 * for unaddressable pages, at some point. But for now
730 * keep things as they are.
731 */
732 get_page(page);
733 rss[mm_counter(page)]++;
734 page_dup_rmap(page, false);
735
736 /*
737 * We do not preserve soft-dirty information, because so
738 * far, checkpoint/restore is the only feature that
739 * requires that. And checkpoint/restore does not work
740 * when a device driver is involved (you cannot easily
741 * save and restore device driver state).
742 */
743 if (is_write_device_private_entry(entry) &&
744 is_cow_mapping(vm_flags)) {
745 make_device_private_entry_read(&entry);
746 pte = swp_entry_to_pte(entry);
747 set_pte_at(src_mm, addr, src_pte, pte);
748 }
749 }
750 goto out_set_pte;
751 }
752
753 /*
754 * If it's a COW mapping, write protect it both
755 * in the parent and the child
756 */
757 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
758 ptep_set_wrprotect(src_mm, addr, src_pte);
759 pte = pte_wrprotect(pte);
760 }
761
762 /*
763 * If it's a shared mapping, mark it clean in
764 * the child
765 */
766 if (vm_flags & VM_SHARED)
767 pte = pte_mkclean(pte);
768 pte = pte_mkold(pte);
769
770 page = vm_normal_page(vma, addr, pte);
771 if (page) {
772 get_page(page);
773 page_dup_rmap(page, false);
774 rss[mm_counter(page)]++;
775 } else if (pte_devmap(pte)) {
776 page = pte_page(pte);
777 }
778
779out_set_pte:
780 set_pte_at(dst_mm, addr, dst_pte, pte);
781 return 0;
782}
783
784static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
785 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
786 unsigned long addr, unsigned long end)
787{
788 pte_t *orig_src_pte, *orig_dst_pte;
789 pte_t *src_pte, *dst_pte;
790 spinlock_t *src_ptl, *dst_ptl;
791 int progress = 0;
792 int rss[NR_MM_COUNTERS];
793 swp_entry_t entry = (swp_entry_t){0};
794
795again:
796 init_rss_vec(rss);
797
798 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
799 if (!dst_pte)
800 return -ENOMEM;
801 src_pte = pte_offset_map(src_pmd, addr);
802 src_ptl = pte_lockptr(src_mm, src_pmd);
803 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
804 orig_src_pte = src_pte;
805 orig_dst_pte = dst_pte;
806 arch_enter_lazy_mmu_mode();
807
808 do {
809 /*
810 * We are holding two locks at this point - either of them
811 * could generate latencies in another task on another CPU.
812 */
813 if (progress >= 32) {
814 progress = 0;
815 if (need_resched() ||
816 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
817 break;
818 }
819 if (pte_none(*src_pte)) {
820 progress++;
821 continue;
822 }
823 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
824 vma, addr, rss);
825 if (entry.val)
826 break;
827 progress += 8;
828 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
829
830 arch_leave_lazy_mmu_mode();
831 spin_unlock(src_ptl);
832 pte_unmap(orig_src_pte);
833 add_mm_rss_vec(dst_mm, rss);
834 pte_unmap_unlock(orig_dst_pte, dst_ptl);
835 cond_resched();
836
837 if (entry.val) {
838 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
839 return -ENOMEM;
840 progress = 0;
841 }
842 if (addr != end)
843 goto again;
844 return 0;
845}
846
847static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
848 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
849 unsigned long addr, unsigned long end)
850{
851 pmd_t *src_pmd, *dst_pmd;
852 unsigned long next;
853
854 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
855 if (!dst_pmd)
856 return -ENOMEM;
857 src_pmd = pmd_offset(src_pud, addr);
858 do {
859 next = pmd_addr_end(addr, end);
860 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
861 || pmd_devmap(*src_pmd)) {
862 int err;
863 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
864 err = copy_huge_pmd(dst_mm, src_mm,
865 dst_pmd, src_pmd, addr, vma);
866 if (err == -ENOMEM)
867 return -ENOMEM;
868 if (!err)
869 continue;
870 /* fall through */
871 }
872 if (pmd_none_or_clear_bad(src_pmd))
873 continue;
874 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
875 vma, addr, next))
876 return -ENOMEM;
877 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
878 return 0;
879}
880
881static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
882 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
883 unsigned long addr, unsigned long end)
884{
885 pud_t *src_pud, *dst_pud;
886 unsigned long next;
887
888 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
889 if (!dst_pud)
890 return -ENOMEM;
891 src_pud = pud_offset(src_p4d, addr);
892 do {
893 next = pud_addr_end(addr, end);
894 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
895 int err;
896
897 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
898 err = copy_huge_pud(dst_mm, src_mm,
899 dst_pud, src_pud, addr, vma);
900 if (err == -ENOMEM)
901 return -ENOMEM;
902 if (!err)
903 continue;
904 /* fall through */
905 }
906 if (pud_none_or_clear_bad(src_pud))
907 continue;
908 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
909 vma, addr, next))
910 return -ENOMEM;
911 } while (dst_pud++, src_pud++, addr = next, addr != end);
912 return 0;
913}
914
915static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
916 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
917 unsigned long addr, unsigned long end)
918{
919 p4d_t *src_p4d, *dst_p4d;
920 unsigned long next;
921
922 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
923 if (!dst_p4d)
924 return -ENOMEM;
925 src_p4d = p4d_offset(src_pgd, addr);
926 do {
927 next = p4d_addr_end(addr, end);
928 if (p4d_none_or_clear_bad(src_p4d))
929 continue;
930 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
931 vma, addr, next))
932 return -ENOMEM;
933 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
934 return 0;
935}
936
937int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
938 struct vm_area_struct *vma)
939{
940 pgd_t *src_pgd, *dst_pgd;
941 unsigned long next;
942 unsigned long addr = vma->vm_start;
943 unsigned long end = vma->vm_end;
944 struct mmu_notifier_range range;
945 bool is_cow;
946 int ret;
947
948 /*
949 * Don't copy ptes where a page fault will fill them correctly.
950 * Fork becomes much lighter when there are big shared or private
951 * readonly mappings. The tradeoff is that copy_page_range is more
952 * efficient than faulting.
953 */
954 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
955 !vma->anon_vma)
956 return 0;
957
958 if (is_vm_hugetlb_page(vma))
959 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
960
961 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
962 /*
963 * We do not free on error cases below as remove_vma
964 * gets called on error from higher level routine
965 */
966 ret = track_pfn_copy(vma);
967 if (ret)
968 return ret;
969 }
970
971 /*
972 * We need to invalidate the secondary MMU mappings only when
973 * there could be a permission downgrade on the ptes of the
974 * parent mm. And a permission downgrade will only happen if
975 * is_cow_mapping() returns true.
976 */
977 is_cow = is_cow_mapping(vma->vm_flags);
978
979 if (is_cow) {
980 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
981 0, vma, src_mm, addr, end);
982 mmu_notifier_invalidate_range_start(&range);
983 }
984
985 ret = 0;
986 dst_pgd = pgd_offset(dst_mm, addr);
987 src_pgd = pgd_offset(src_mm, addr);
988 do {
989 next = pgd_addr_end(addr, end);
990 if (pgd_none_or_clear_bad(src_pgd))
991 continue;
992 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
993 vma, addr, next))) {
994 ret = -ENOMEM;
995 break;
996 }
997 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
998
999 if (is_cow)
1000 mmu_notifier_invalidate_range_end(&range);
1001 return ret;
1002}
1003
1004static unsigned long zap_pte_range(struct mmu_gather *tlb,
1005 struct vm_area_struct *vma, pmd_t *pmd,
1006 unsigned long addr, unsigned long end,
1007 struct zap_details *details)
1008{
1009 struct mm_struct *mm = tlb->mm;
1010 int force_flush = 0;
1011 int rss[NR_MM_COUNTERS];
1012 spinlock_t *ptl;
1013 pte_t *start_pte;
1014 pte_t *pte;
1015 swp_entry_t entry;
1016
1017 tlb_change_page_size(tlb, PAGE_SIZE);
1018again:
1019 init_rss_vec(rss);
1020 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1021 pte = start_pte;
1022 flush_tlb_batched_pending(mm);
1023 arch_enter_lazy_mmu_mode();
1024 do {
1025 pte_t ptent = *pte;
1026 if (pte_none(ptent))
1027 continue;
1028
1029 if (need_resched())
1030 break;
1031
1032 if (pte_present(ptent)) {
1033 struct page *page;
1034
1035 page = vm_normal_page(vma, addr, ptent);
1036 if (unlikely(details) && page) {
1037 /*
1038 * unmap_shared_mapping_pages() wants to
1039 * invalidate cache without truncating:
1040 * unmap shared but keep private pages.
1041 */
1042 if (details->check_mapping &&
1043 details->check_mapping != page_rmapping(page))
1044 continue;
1045 }
1046 ptent = ptep_get_and_clear_full(mm, addr, pte,
1047 tlb->fullmm);
1048 tlb_remove_tlb_entry(tlb, pte, addr);
1049 if (unlikely(!page))
1050 continue;
1051
1052 if (!PageAnon(page)) {
1053 if (pte_dirty(ptent)) {
1054 force_flush = 1;
1055 set_page_dirty(page);
1056 }
1057 if (pte_young(ptent) &&
1058 likely(!(vma->vm_flags & VM_SEQ_READ)))
1059 mark_page_accessed(page);
1060 }
1061 rss[mm_counter(page)]--;
1062 page_remove_rmap(page, false);
1063 if (unlikely(page_mapcount(page) < 0))
1064 print_bad_pte(vma, addr, ptent, page);
1065 if (unlikely(__tlb_remove_page(tlb, page))) {
1066 force_flush = 1;
1067 addr += PAGE_SIZE;
1068 break;
1069 }
1070 continue;
1071 }
1072
1073 entry = pte_to_swp_entry(ptent);
1074 if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1075 struct page *page = device_private_entry_to_page(entry);
1076
1077 if (unlikely(details && details->check_mapping)) {
1078 /*
1079 * unmap_shared_mapping_pages() wants to
1080 * invalidate cache without truncating:
1081 * unmap shared but keep private pages.
1082 */
1083 if (details->check_mapping !=
1084 page_rmapping(page))
1085 continue;
1086 }
1087
1088 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1089 rss[mm_counter(page)]--;
1090 page_remove_rmap(page, false);
1091 put_page(page);
1092 continue;
1093 }
1094
1095 /* If details->check_mapping, we leave swap entries. */
1096 if (unlikely(details))
1097 continue;
1098
1099 if (!non_swap_entry(entry))
1100 rss[MM_SWAPENTS]--;
1101 else if (is_migration_entry(entry)) {
1102 struct page *page;
1103
1104 page = migration_entry_to_page(entry);
1105 rss[mm_counter(page)]--;
1106 }
1107 if (unlikely(!free_swap_and_cache(entry)))
1108 print_bad_pte(vma, addr, ptent, NULL);
1109 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1110 } while (pte++, addr += PAGE_SIZE, addr != end);
1111
1112 add_mm_rss_vec(mm, rss);
1113 arch_leave_lazy_mmu_mode();
1114
1115 /* Do the actual TLB flush before dropping ptl */
1116 if (force_flush)
1117 tlb_flush_mmu_tlbonly(tlb);
1118 pte_unmap_unlock(start_pte, ptl);
1119
1120 /*
1121 * If we forced a TLB flush (either due to running out of
1122 * batch buffers or because we needed to flush dirty TLB
1123 * entries before releasing the ptl), free the batched
1124 * memory too. Restart if we didn't do everything.
1125 */
1126 if (force_flush) {
1127 force_flush = 0;
1128 tlb_flush_mmu(tlb);
1129 }
1130
1131 if (addr != end) {
1132 cond_resched();
1133 goto again;
1134 }
1135
1136 return addr;
1137}
1138
1139static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1140 struct vm_area_struct *vma, pud_t *pud,
1141 unsigned long addr, unsigned long end,
1142 struct zap_details *details)
1143{
1144 pmd_t *pmd;
1145 unsigned long next;
1146
1147 pmd = pmd_offset(pud, addr);
1148 do {
1149 next = pmd_addr_end(addr, end);
1150 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1151 if (next - addr != HPAGE_PMD_SIZE)
1152 __split_huge_pmd(vma, pmd, addr, false, NULL);
1153 else if (zap_huge_pmd(tlb, vma, pmd, addr))
1154 goto next;
1155 /* fall through */
1156 }
1157 /*
1158 * Here there can be other concurrent MADV_DONTNEED or
1159 * trans huge page faults running, and if the pmd is
1160 * none or trans huge it can change under us. This is
1161 * because MADV_DONTNEED holds the mmap_sem in read
1162 * mode.
1163 */
1164 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1165 goto next;
1166 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1167next:
1168 cond_resched();
1169 } while (pmd++, addr = next, addr != end);
1170
1171 return addr;
1172}
1173
1174static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1175 struct vm_area_struct *vma, p4d_t *p4d,
1176 unsigned long addr, unsigned long end,
1177 struct zap_details *details)
1178{
1179 pud_t *pud;
1180 unsigned long next;
1181
1182 pud = pud_offset(p4d, addr);
1183 do {
1184 next = pud_addr_end(addr, end);
1185 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1186 if (next - addr != HPAGE_PUD_SIZE) {
1187 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1188 split_huge_pud(vma, pud, addr);
1189 } else if (zap_huge_pud(tlb, vma, pud, addr))
1190 goto next;
1191 /* fall through */
1192 }
1193 if (pud_none_or_clear_bad(pud))
1194 continue;
1195 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1196next:
1197 cond_resched();
1198 } while (pud++, addr = next, addr != end);
1199
1200 return addr;
1201}
1202
1203static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1204 struct vm_area_struct *vma, pgd_t *pgd,
1205 unsigned long addr, unsigned long end,
1206 struct zap_details *details)
1207{
1208 p4d_t *p4d;
1209 unsigned long next;
1210
1211 p4d = p4d_offset(pgd, addr);
1212 do {
1213 next = p4d_addr_end(addr, end);
1214 if (p4d_none_or_clear_bad(p4d))
1215 continue;
1216 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1217 } while (p4d++, addr = next, addr != end);
1218
1219 return addr;
1220}
1221
1222void unmap_page_range(struct mmu_gather *tlb,
1223 struct vm_area_struct *vma,
1224 unsigned long addr, unsigned long end,
1225 struct zap_details *details)
1226{
1227 pgd_t *pgd;
1228 unsigned long next;
1229
1230 BUG_ON(addr >= end);
1231 tlb_start_vma(tlb, vma);
1232 pgd = pgd_offset(vma->vm_mm, addr);
1233 do {
1234 next = pgd_addr_end(addr, end);
1235 if (pgd_none_or_clear_bad(pgd))
1236 continue;
1237 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1238 } while (pgd++, addr = next, addr != end);
1239 tlb_end_vma(tlb, vma);
1240}
1241
1242
1243static void unmap_single_vma(struct mmu_gather *tlb,
1244 struct vm_area_struct *vma, unsigned long start_addr,
1245 unsigned long end_addr,
1246 struct zap_details *details)
1247{
1248 unsigned long start = max(vma->vm_start, start_addr);
1249 unsigned long end;
1250
1251 if (start >= vma->vm_end)
1252 return;
1253 end = min(vma->vm_end, end_addr);
1254 if (end <= vma->vm_start)
1255 return;
1256
1257 if (vma->vm_file)
1258 uprobe_munmap(vma, start, end);
1259
1260 if (unlikely(vma->vm_flags & VM_PFNMAP))
1261 untrack_pfn(vma, 0, 0);
1262
1263 if (start != end) {
1264 if (unlikely(is_vm_hugetlb_page(vma))) {
1265 /*
1266 * It is undesirable to test vma->vm_file as it
1267 * should be non-null for valid hugetlb area.
1268 * However, vm_file will be NULL in the error
1269 * cleanup path of mmap_region. When
1270 * hugetlbfs ->mmap method fails,
1271 * mmap_region() nullifies vma->vm_file
1272 * before calling this function to clean up.
1273 * Since no pte has actually been setup, it is
1274 * safe to do nothing in this case.
1275 */
1276 if (vma->vm_file) {
1277 i_mmap_lock_write(vma->vm_file->f_mapping);
1278 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1279 i_mmap_unlock_write(vma->vm_file->f_mapping);
1280 }
1281 } else
1282 unmap_page_range(tlb, vma, start, end, details);
1283 }
1284}
1285
1286/**
1287 * unmap_vmas - unmap a range of memory covered by a list of vma's
1288 * @tlb: address of the caller's struct mmu_gather
1289 * @vma: the starting vma
1290 * @start_addr: virtual address at which to start unmapping
1291 * @end_addr: virtual address at which to end unmapping
1292 *
1293 * Unmap all pages in the vma list.
1294 *
1295 * Only addresses between `start' and `end' will be unmapped.
1296 *
1297 * The VMA list must be sorted in ascending virtual address order.
1298 *
1299 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1300 * range after unmap_vmas() returns. So the only responsibility here is to
1301 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1302 * drops the lock and schedules.
1303 */
1304void unmap_vmas(struct mmu_gather *tlb,
1305 struct vm_area_struct *vma, unsigned long start_addr,
1306 unsigned long end_addr)
1307{
1308 struct mmu_notifier_range range;
1309
1310 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1311 start_addr, end_addr);
1312 mmu_notifier_invalidate_range_start(&range);
1313 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1314 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1315 mmu_notifier_invalidate_range_end(&range);
1316}
1317
1318/**
1319 * zap_page_range - remove user pages in a given range
1320 * @vma: vm_area_struct holding the applicable pages
1321 * @start: starting address of pages to zap
1322 * @size: number of bytes to zap
1323 *
1324 * Caller must protect the VMA list
1325 */
1326void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1327 unsigned long size)
1328{
1329 struct mmu_notifier_range range;
1330 struct mmu_gather tlb;
1331
1332 lru_add_drain();
1333 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1334 start, start + size);
1335 tlb_gather_mmu(&tlb, vma->vm_mm, start, range.end);
1336 update_hiwater_rss(vma->vm_mm);
1337 mmu_notifier_invalidate_range_start(&range);
1338 for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
1339 unmap_single_vma(&tlb, vma, start, range.end, NULL);
1340 mmu_notifier_invalidate_range_end(&range);
1341 tlb_finish_mmu(&tlb, start, range.end);
1342}
1343
1344/**
1345 * zap_page_range_single - remove user pages in a given range
1346 * @vma: vm_area_struct holding the applicable pages
1347 * @address: starting address of pages to zap
1348 * @size: number of bytes to zap
1349 * @details: details of shared cache invalidation
1350 *
1351 * The range must fit into one VMA.
1352 */
1353static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1354 unsigned long size, struct zap_details *details)
1355{
1356 struct mmu_notifier_range range;
1357 struct mmu_gather tlb;
1358
1359 lru_add_drain();
1360 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1361 address, address + size);
1362 tlb_gather_mmu(&tlb, vma->vm_mm, address, range.end);
1363 update_hiwater_rss(vma->vm_mm);
1364 mmu_notifier_invalidate_range_start(&range);
1365 unmap_single_vma(&tlb, vma, address, range.end, details);
1366 mmu_notifier_invalidate_range_end(&range);
1367 tlb_finish_mmu(&tlb, address, range.end);
1368}
1369
1370/**
1371 * zap_vma_ptes - remove ptes mapping the vma
1372 * @vma: vm_area_struct holding ptes to be zapped
1373 * @address: starting address of pages to zap
1374 * @size: number of bytes to zap
1375 *
1376 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1377 *
1378 * The entire address range must be fully contained within the vma.
1379 *
1380 */
1381void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1382 unsigned long size)
1383{
1384 if (address < vma->vm_start || address + size > vma->vm_end ||
1385 !(vma->vm_flags & VM_PFNMAP))
1386 return;
1387
1388 zap_page_range_single(vma, address, size, NULL);
1389}
1390EXPORT_SYMBOL_GPL(zap_vma_ptes);
1391
1392pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1393 spinlock_t **ptl)
1394{
1395 pgd_t *pgd;
1396 p4d_t *p4d;
1397 pud_t *pud;
1398 pmd_t *pmd;
1399
1400 pgd = pgd_offset(mm, addr);
1401 p4d = p4d_alloc(mm, pgd, addr);
1402 if (!p4d)
1403 return NULL;
1404 pud = pud_alloc(mm, p4d, addr);
1405 if (!pud)
1406 return NULL;
1407 pmd = pmd_alloc(mm, pud, addr);
1408 if (!pmd)
1409 return NULL;
1410
1411 VM_BUG_ON(pmd_trans_huge(*pmd));
1412 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1413}
1414
1415/*
1416 * This is the old fallback for page remapping.
1417 *
1418 * For historical reasons, it only allows reserved pages. Only
1419 * old drivers should use this, and they needed to mark their
1420 * pages reserved for the old functions anyway.
1421 */
1422static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1423 struct page *page, pgprot_t prot)
1424{
1425 struct mm_struct *mm = vma->vm_mm;
1426 int retval;
1427 pte_t *pte;
1428 spinlock_t *ptl;
1429
1430 retval = -EINVAL;
1431 if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1432 goto out;
1433 retval = -ENOMEM;
1434 flush_dcache_page(page);
1435 pte = get_locked_pte(mm, addr, &ptl);
1436 if (!pte)
1437 goto out;
1438 retval = -EBUSY;
1439 if (!pte_none(*pte))
1440 goto out_unlock;
1441
1442 /* Ok, finally just insert the thing.. */
1443 get_page(page);
1444 inc_mm_counter_fast(mm, mm_counter_file(page));
1445 page_add_file_rmap(page, false);
1446 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1447
1448 retval = 0;
1449out_unlock:
1450 pte_unmap_unlock(pte, ptl);
1451out:
1452 return retval;
1453}
1454
1455/**
1456 * vm_insert_page - insert single page into user vma
1457 * @vma: user vma to map to
1458 * @addr: target user address of this page
1459 * @page: source kernel page
1460 *
1461 * This allows drivers to insert individual pages they've allocated
1462 * into a user vma.
1463 *
1464 * The page has to be a nice clean _individual_ kernel allocation.
1465 * If you allocate a compound page, you need to have marked it as
1466 * such (__GFP_COMP), or manually just split the page up yourself
1467 * (see split_page()).
1468 *
1469 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1470 * took an arbitrary page protection parameter. This doesn't allow
1471 * that. Your vma protection will have to be set up correctly, which
1472 * means that if you want a shared writable mapping, you'd better
1473 * ask for a shared writable mapping!
1474 *
1475 * The page does not need to be reserved.
1476 *
1477 * Usually this function is called from f_op->mmap() handler
1478 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1479 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1480 * function from other places, for example from page-fault handler.
1481 *
1482 * Return: %0 on success, negative error code otherwise.
1483 */
1484int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1485 struct page *page)
1486{
1487 if (addr < vma->vm_start || addr >= vma->vm_end)
1488 return -EFAULT;
1489 if (!page_count(page))
1490 return -EINVAL;
1491 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1492 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1493 BUG_ON(vma->vm_flags & VM_PFNMAP);
1494 vma->vm_flags |= VM_MIXEDMAP;
1495 }
1496 return insert_page(vma, addr, page, vma->vm_page_prot);
1497}
1498EXPORT_SYMBOL(vm_insert_page);
1499
1500/*
1501 * __vm_map_pages - maps range of kernel pages into user vma
1502 * @vma: user vma to map to
1503 * @pages: pointer to array of source kernel pages
1504 * @num: number of pages in page array
1505 * @offset: user's requested vm_pgoff
1506 *
1507 * This allows drivers to map range of kernel pages into a user vma.
1508 *
1509 * Return: 0 on success and error code otherwise.
1510 */
1511static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1512 unsigned long num, unsigned long offset)
1513{
1514 unsigned long count = vma_pages(vma);
1515 unsigned long uaddr = vma->vm_start;
1516 int ret, i;
1517
1518 /* Fail if the user requested offset is beyond the end of the object */
1519 if (offset >= num)
1520 return -ENXIO;
1521
1522 /* Fail if the user requested size exceeds available object size */
1523 if (count > num - offset)
1524 return -ENXIO;
1525
1526 for (i = 0; i < count; i++) {
1527 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
1528 if (ret < 0)
1529 return ret;
1530 uaddr += PAGE_SIZE;
1531 }
1532
1533 return 0;
1534}
1535
1536/**
1537 * vm_map_pages - maps range of kernel pages starts with non zero offset
1538 * @vma: user vma to map to
1539 * @pages: pointer to array of source kernel pages
1540 * @num: number of pages in page array
1541 *
1542 * Maps an object consisting of @num pages, catering for the user's
1543 * requested vm_pgoff
1544 *
1545 * If we fail to insert any page into the vma, the function will return
1546 * immediately leaving any previously inserted pages present. Callers
1547 * from the mmap handler may immediately return the error as their caller
1548 * will destroy the vma, removing any successfully inserted pages. Other
1549 * callers should make their own arrangements for calling unmap_region().
1550 *
1551 * Context: Process context. Called by mmap handlers.
1552 * Return: 0 on success and error code otherwise.
1553 */
1554int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1555 unsigned long num)
1556{
1557 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
1558}
1559EXPORT_SYMBOL(vm_map_pages);
1560
1561/**
1562 * vm_map_pages_zero - map range of kernel pages starts with zero offset
1563 * @vma: user vma to map to
1564 * @pages: pointer to array of source kernel pages
1565 * @num: number of pages in page array
1566 *
1567 * Similar to vm_map_pages(), except that it explicitly sets the offset
1568 * to 0. This function is intended for the drivers that did not consider
1569 * vm_pgoff.
1570 *
1571 * Context: Process context. Called by mmap handlers.
1572 * Return: 0 on success and error code otherwise.
1573 */
1574int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
1575 unsigned long num)
1576{
1577 return __vm_map_pages(vma, pages, num, 0);
1578}
1579EXPORT_SYMBOL(vm_map_pages_zero);
1580
1581static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1582 pfn_t pfn, pgprot_t prot, bool mkwrite)
1583{
1584 struct mm_struct *mm = vma->vm_mm;
1585 pte_t *pte, entry;
1586 spinlock_t *ptl;
1587
1588 pte = get_locked_pte(mm, addr, &ptl);
1589 if (!pte)
1590 return VM_FAULT_OOM;
1591 if (!pte_none(*pte)) {
1592 if (mkwrite) {
1593 /*
1594 * For read faults on private mappings the PFN passed
1595 * in may not match the PFN we have mapped if the
1596 * mapped PFN is a writeable COW page. In the mkwrite
1597 * case we are creating a writable PTE for a shared
1598 * mapping and we expect the PFNs to match. If they
1599 * don't match, we are likely racing with block
1600 * allocation and mapping invalidation so just skip the
1601 * update.
1602 */
1603 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
1604 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
1605 goto out_unlock;
1606 }
1607 entry = pte_mkyoung(*pte);
1608 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1609 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
1610 update_mmu_cache(vma, addr, pte);
1611 }
1612 goto out_unlock;
1613 }
1614
1615 /* Ok, finally just insert the thing.. */
1616 if (pfn_t_devmap(pfn))
1617 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1618 else
1619 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1620
1621 if (mkwrite) {
1622 entry = pte_mkyoung(entry);
1623 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1624 }
1625
1626 set_pte_at(mm, addr, pte, entry);
1627 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1628
1629out_unlock:
1630 pte_unmap_unlock(pte, ptl);
1631 return VM_FAULT_NOPAGE;
1632}
1633
1634/**
1635 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1636 * @vma: user vma to map to
1637 * @addr: target user address of this page
1638 * @pfn: source kernel pfn
1639 * @pgprot: pgprot flags for the inserted page
1640 *
1641 * This is exactly like vmf_insert_pfn(), except that it allows drivers to
1642 * to override pgprot on a per-page basis.
1643 *
1644 * This only makes sense for IO mappings, and it makes no sense for
1645 * COW mappings. In general, using multiple vmas is preferable;
1646 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
1647 * impractical.
1648 *
1649 * Context: Process context. May allocate using %GFP_KERNEL.
1650 * Return: vm_fault_t value.
1651 */
1652vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1653 unsigned long pfn, pgprot_t pgprot)
1654{
1655 /*
1656 * Technically, architectures with pte_special can avoid all these
1657 * restrictions (same for remap_pfn_range). However we would like
1658 * consistency in testing and feature parity among all, so we should
1659 * try to keep these invariants in place for everybody.
1660 */
1661 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1662 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1663 (VM_PFNMAP|VM_MIXEDMAP));
1664 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1665 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1666
1667 if (addr < vma->vm_start || addr >= vma->vm_end)
1668 return VM_FAULT_SIGBUS;
1669
1670 if (!pfn_modify_allowed(pfn, pgprot))
1671 return VM_FAULT_SIGBUS;
1672
1673 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1674
1675 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1676 false);
1677}
1678EXPORT_SYMBOL(vmf_insert_pfn_prot);
1679
1680/**
1681 * vmf_insert_pfn - insert single pfn into user vma
1682 * @vma: user vma to map to
1683 * @addr: target user address of this page
1684 * @pfn: source kernel pfn
1685 *
1686 * Similar to vm_insert_page, this allows drivers to insert individual pages
1687 * they've allocated into a user vma. Same comments apply.
1688 *
1689 * This function should only be called from a vm_ops->fault handler, and
1690 * in that case the handler should return the result of this function.
1691 *
1692 * vma cannot be a COW mapping.
1693 *
1694 * As this is called only for pages that do not currently exist, we
1695 * do not need to flush old virtual caches or the TLB.
1696 *
1697 * Context: Process context. May allocate using %GFP_KERNEL.
1698 * Return: vm_fault_t value.
1699 */
1700vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1701 unsigned long pfn)
1702{
1703 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1704}
1705EXPORT_SYMBOL(vmf_insert_pfn);
1706
1707static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
1708{
1709 /* these checks mirror the abort conditions in vm_normal_page */
1710 if (vma->vm_flags & VM_MIXEDMAP)
1711 return true;
1712 if (pfn_t_devmap(pfn))
1713 return true;
1714 if (pfn_t_special(pfn))
1715 return true;
1716 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
1717 return true;
1718 return false;
1719}
1720
1721static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
1722 unsigned long addr, pfn_t pfn, bool mkwrite)
1723{
1724 pgprot_t pgprot = vma->vm_page_prot;
1725 int err;
1726
1727 BUG_ON(!vm_mixed_ok(vma, pfn));
1728
1729 if (addr < vma->vm_start || addr >= vma->vm_end)
1730 return VM_FAULT_SIGBUS;
1731
1732 track_pfn_insert(vma, &pgprot, pfn);
1733
1734 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
1735 return VM_FAULT_SIGBUS;
1736
1737 /*
1738 * If we don't have pte special, then we have to use the pfn_valid()
1739 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1740 * refcount the page if pfn_valid is true (hence insert_page rather
1741 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1742 * without pte special, it would there be refcounted as a normal page.
1743 */
1744 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
1745 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1746 struct page *page;
1747
1748 /*
1749 * At this point we are committed to insert_page()
1750 * regardless of whether the caller specified flags that
1751 * result in pfn_t_has_page() == false.
1752 */
1753 page = pfn_to_page(pfn_t_to_pfn(pfn));
1754 err = insert_page(vma, addr, page, pgprot);
1755 } else {
1756 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1757 }
1758
1759 if (err == -ENOMEM)
1760 return VM_FAULT_OOM;
1761 if (err < 0 && err != -EBUSY)
1762 return VM_FAULT_SIGBUS;
1763
1764 return VM_FAULT_NOPAGE;
1765}
1766
1767vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1768 pfn_t pfn)
1769{
1770 return __vm_insert_mixed(vma, addr, pfn, false);
1771}
1772EXPORT_SYMBOL(vmf_insert_mixed);
1773
1774/*
1775 * If the insertion of PTE failed because someone else already added a
1776 * different entry in the mean time, we treat that as success as we assume
1777 * the same entry was actually inserted.
1778 */
1779vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
1780 unsigned long addr, pfn_t pfn)
1781{
1782 return __vm_insert_mixed(vma, addr, pfn, true);
1783}
1784EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
1785
1786/*
1787 * maps a range of physical memory into the requested pages. the old
1788 * mappings are removed. any references to nonexistent pages results
1789 * in null mappings (currently treated as "copy-on-access")
1790 */
1791static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1792 unsigned long addr, unsigned long end,
1793 unsigned long pfn, pgprot_t prot)
1794{
1795 pte_t *pte;
1796 spinlock_t *ptl;
1797 int err = 0;
1798
1799 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1800 if (!pte)
1801 return -ENOMEM;
1802 arch_enter_lazy_mmu_mode();
1803 do {
1804 BUG_ON(!pte_none(*pte));
1805 if (!pfn_modify_allowed(pfn, prot)) {
1806 err = -EACCES;
1807 break;
1808 }
1809 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1810 pfn++;
1811 } while (pte++, addr += PAGE_SIZE, addr != end);
1812 arch_leave_lazy_mmu_mode();
1813 pte_unmap_unlock(pte - 1, ptl);
1814 return err;
1815}
1816
1817static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1818 unsigned long addr, unsigned long end,
1819 unsigned long pfn, pgprot_t prot)
1820{
1821 pmd_t *pmd;
1822 unsigned long next;
1823 int err;
1824
1825 pfn -= addr >> PAGE_SHIFT;
1826 pmd = pmd_alloc(mm, pud, addr);
1827 if (!pmd)
1828 return -ENOMEM;
1829 VM_BUG_ON(pmd_trans_huge(*pmd));
1830 do {
1831 next = pmd_addr_end(addr, end);
1832 err = remap_pte_range(mm, pmd, addr, next,
1833 pfn + (addr >> PAGE_SHIFT), prot);
1834 if (err)
1835 return err;
1836 } while (pmd++, addr = next, addr != end);
1837 return 0;
1838}
1839
1840static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
1841 unsigned long addr, unsigned long end,
1842 unsigned long pfn, pgprot_t prot)
1843{
1844 pud_t *pud;
1845 unsigned long next;
1846 int err;
1847
1848 pfn -= addr >> PAGE_SHIFT;
1849 pud = pud_alloc(mm, p4d, addr);
1850 if (!pud)
1851 return -ENOMEM;
1852 do {
1853 next = pud_addr_end(addr, end);
1854 err = remap_pmd_range(mm, pud, addr, next,
1855 pfn + (addr >> PAGE_SHIFT), prot);
1856 if (err)
1857 return err;
1858 } while (pud++, addr = next, addr != end);
1859 return 0;
1860}
1861
1862static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
1863 unsigned long addr, unsigned long end,
1864 unsigned long pfn, pgprot_t prot)
1865{
1866 p4d_t *p4d;
1867 unsigned long next;
1868 int err;
1869
1870 pfn -= addr >> PAGE_SHIFT;
1871 p4d = p4d_alloc(mm, pgd, addr);
1872 if (!p4d)
1873 return -ENOMEM;
1874 do {
1875 next = p4d_addr_end(addr, end);
1876 err = remap_pud_range(mm, p4d, addr, next,
1877 pfn + (addr >> PAGE_SHIFT), prot);
1878 if (err)
1879 return err;
1880 } while (p4d++, addr = next, addr != end);
1881 return 0;
1882}
1883
1884/**
1885 * remap_pfn_range - remap kernel memory to userspace
1886 * @vma: user vma to map to
1887 * @addr: target user address to start at
1888 * @pfn: physical address of kernel memory
1889 * @size: size of map area
1890 * @prot: page protection flags for this mapping
1891 *
1892 * Note: this is only safe if the mm semaphore is held when called.
1893 *
1894 * Return: %0 on success, negative error code otherwise.
1895 */
1896int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1897 unsigned long pfn, unsigned long size, pgprot_t prot)
1898{
1899 pgd_t *pgd;
1900 unsigned long next;
1901 unsigned long end = addr + PAGE_ALIGN(size);
1902 struct mm_struct *mm = vma->vm_mm;
1903 unsigned long remap_pfn = pfn;
1904 int err;
1905
1906 /*
1907 * Physically remapped pages are special. Tell the
1908 * rest of the world about it:
1909 * VM_IO tells people not to look at these pages
1910 * (accesses can have side effects).
1911 * VM_PFNMAP tells the core MM that the base pages are just
1912 * raw PFN mappings, and do not have a "struct page" associated
1913 * with them.
1914 * VM_DONTEXPAND
1915 * Disable vma merging and expanding with mremap().
1916 * VM_DONTDUMP
1917 * Omit vma from core dump, even when VM_IO turned off.
1918 *
1919 * There's a horrible special case to handle copy-on-write
1920 * behaviour that some programs depend on. We mark the "original"
1921 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1922 * See vm_normal_page() for details.
1923 */
1924 if (is_cow_mapping(vma->vm_flags)) {
1925 if (addr != vma->vm_start || end != vma->vm_end)
1926 return -EINVAL;
1927 vma->vm_pgoff = pfn;
1928 }
1929
1930 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1931 if (err)
1932 return -EINVAL;
1933
1934 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1935
1936 BUG_ON(addr >= end);
1937 pfn -= addr >> PAGE_SHIFT;
1938 pgd = pgd_offset(mm, addr);
1939 flush_cache_range(vma, addr, end);
1940 do {
1941 next = pgd_addr_end(addr, end);
1942 err = remap_p4d_range(mm, pgd, addr, next,
1943 pfn + (addr >> PAGE_SHIFT), prot);
1944 if (err)
1945 break;
1946 } while (pgd++, addr = next, addr != end);
1947
1948 if (err)
1949 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1950
1951 return err;
1952}
1953EXPORT_SYMBOL(remap_pfn_range);
1954
1955/**
1956 * vm_iomap_memory - remap memory to userspace
1957 * @vma: user vma to map to
1958 * @start: start of area
1959 * @len: size of area
1960 *
1961 * This is a simplified io_remap_pfn_range() for common driver use. The
1962 * driver just needs to give us the physical memory range to be mapped,
1963 * we'll figure out the rest from the vma information.
1964 *
1965 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1966 * whatever write-combining details or similar.
1967 *
1968 * Return: %0 on success, negative error code otherwise.
1969 */
1970int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1971{
1972 unsigned long vm_len, pfn, pages;
1973
1974 /* Check that the physical memory area passed in looks valid */
1975 if (start + len < start)
1976 return -EINVAL;
1977 /*
1978 * You *really* shouldn't map things that aren't page-aligned,
1979 * but we've historically allowed it because IO memory might
1980 * just have smaller alignment.
1981 */
1982 len += start & ~PAGE_MASK;
1983 pfn = start >> PAGE_SHIFT;
1984 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1985 if (pfn + pages < pfn)
1986 return -EINVAL;
1987
1988 /* We start the mapping 'vm_pgoff' pages into the area */
1989 if (vma->vm_pgoff > pages)
1990 return -EINVAL;
1991 pfn += vma->vm_pgoff;
1992 pages -= vma->vm_pgoff;
1993
1994 /* Can we fit all of the mapping? */
1995 vm_len = vma->vm_end - vma->vm_start;
1996 if (vm_len >> PAGE_SHIFT > pages)
1997 return -EINVAL;
1998
1999 /* Ok, let it rip */
2000 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2001}
2002EXPORT_SYMBOL(vm_iomap_memory);
2003
2004static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2005 unsigned long addr, unsigned long end,
2006 pte_fn_t fn, void *data)
2007{
2008 pte_t *pte;
2009 int err;
2010 spinlock_t *uninitialized_var(ptl);
2011
2012 pte = (mm == &init_mm) ?
2013 pte_alloc_kernel(pmd, addr) :
2014 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2015 if (!pte)
2016 return -ENOMEM;
2017
2018 BUG_ON(pmd_huge(*pmd));
2019
2020 arch_enter_lazy_mmu_mode();
2021
2022 do {
2023 err = fn(pte++, addr, data);
2024 if (err)
2025 break;
2026 } while (addr += PAGE_SIZE, addr != end);
2027
2028 arch_leave_lazy_mmu_mode();
2029
2030 if (mm != &init_mm)
2031 pte_unmap_unlock(pte-1, ptl);
2032 return err;
2033}
2034
2035static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2036 unsigned long addr, unsigned long end,
2037 pte_fn_t fn, void *data)
2038{
2039 pmd_t *pmd;
2040 unsigned long next;
2041 int err;
2042
2043 BUG_ON(pud_huge(*pud));
2044
2045 pmd = pmd_alloc(mm, pud, addr);
2046 if (!pmd)
2047 return -ENOMEM;
2048 do {
2049 next = pmd_addr_end(addr, end);
2050 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2051 if (err)
2052 break;
2053 } while (pmd++, addr = next, addr != end);
2054 return err;
2055}
2056
2057static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2058 unsigned long addr, unsigned long end,
2059 pte_fn_t fn, void *data)
2060{
2061 pud_t *pud;
2062 unsigned long next;
2063 int err;
2064
2065 pud = pud_alloc(mm, p4d, addr);
2066 if (!pud)
2067 return -ENOMEM;
2068 do {
2069 next = pud_addr_end(addr, end);
2070 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2071 if (err)
2072 break;
2073 } while (pud++, addr = next, addr != end);
2074 return err;
2075}
2076
2077static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2078 unsigned long addr, unsigned long end,
2079 pte_fn_t fn, void *data)
2080{
2081 p4d_t *p4d;
2082 unsigned long next;
2083 int err;
2084
2085 p4d = p4d_alloc(mm, pgd, addr);
2086 if (!p4d)
2087 return -ENOMEM;
2088 do {
2089 next = p4d_addr_end(addr, end);
2090 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2091 if (err)
2092 break;
2093 } while (p4d++, addr = next, addr != end);
2094 return err;
2095}
2096
2097/*
2098 * Scan a region of virtual memory, filling in page tables as necessary
2099 * and calling a provided function on each leaf page table.
2100 */
2101int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2102 unsigned long size, pte_fn_t fn, void *data)
2103{
2104 pgd_t *pgd;
2105 unsigned long next;
2106 unsigned long end = addr + size;
2107 int err;
2108
2109 if (WARN_ON(addr >= end))
2110 return -EINVAL;
2111
2112 pgd = pgd_offset(mm, addr);
2113 do {
2114 next = pgd_addr_end(addr, end);
2115 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2116 if (err)
2117 break;
2118 } while (pgd++, addr = next, addr != end);
2119
2120 return err;
2121}
2122EXPORT_SYMBOL_GPL(apply_to_page_range);
2123
2124/*
2125 * handle_pte_fault chooses page fault handler according to an entry which was
2126 * read non-atomically. Before making any commitment, on those architectures
2127 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2128 * parts, do_swap_page must check under lock before unmapping the pte and
2129 * proceeding (but do_wp_page is only called after already making such a check;
2130 * and do_anonymous_page can safely check later on).
2131 */
2132static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2133 pte_t *page_table, pte_t orig_pte)
2134{
2135 int same = 1;
2136#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2137 if (sizeof(pte_t) > sizeof(unsigned long)) {
2138 spinlock_t *ptl = pte_lockptr(mm, pmd);
2139 spin_lock(ptl);
2140 same = pte_same(*page_table, orig_pte);
2141 spin_unlock(ptl);
2142 }
2143#endif
2144 pte_unmap(page_table);
2145 return same;
2146}
2147
2148static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2149{
2150 debug_dma_assert_idle(src);
2151
2152 /*
2153 * If the source page was a PFN mapping, we don't have
2154 * a "struct page" for it. We do a best-effort copy by
2155 * just copying from the original user address. If that
2156 * fails, we just zero-fill it. Live with it.
2157 */
2158 if (unlikely(!src)) {
2159 void *kaddr = kmap_atomic(dst);
2160 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2161
2162 /*
2163 * This really shouldn't fail, because the page is there
2164 * in the page tables. But it might just be unreadable,
2165 * in which case we just give up and fill the result with
2166 * zeroes.
2167 */
2168 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2169 clear_page(kaddr);
2170 kunmap_atomic(kaddr);
2171 flush_dcache_page(dst);
2172 } else
2173 copy_user_highpage(dst, src, va, vma);
2174}
2175
2176static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2177{
2178 struct file *vm_file = vma->vm_file;
2179
2180 if (vm_file)
2181 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2182
2183 /*
2184 * Special mappings (e.g. VDSO) do not have any file so fake
2185 * a default GFP_KERNEL for them.
2186 */
2187 return GFP_KERNEL;
2188}
2189
2190/*
2191 * Notify the address space that the page is about to become writable so that
2192 * it can prohibit this or wait for the page to get into an appropriate state.
2193 *
2194 * We do this without the lock held, so that it can sleep if it needs to.
2195 */
2196static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2197{
2198 vm_fault_t ret;
2199 struct page *page = vmf->page;
2200 unsigned int old_flags = vmf->flags;
2201
2202 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2203
2204 if (vmf->vma->vm_file &&
2205 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2206 return VM_FAULT_SIGBUS;
2207
2208 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2209 /* Restore original flags so that caller is not surprised */
2210 vmf->flags = old_flags;
2211 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2212 return ret;
2213 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2214 lock_page(page);
2215 if (!page->mapping) {
2216 unlock_page(page);
2217 return 0; /* retry */
2218 }
2219 ret |= VM_FAULT_LOCKED;
2220 } else
2221 VM_BUG_ON_PAGE(!PageLocked(page), page);
2222 return ret;
2223}
2224
2225/*
2226 * Handle dirtying of a page in shared file mapping on a write fault.
2227 *
2228 * The function expects the page to be locked and unlocks it.
2229 */
2230static void fault_dirty_shared_page(struct vm_area_struct *vma,
2231 struct page *page)
2232{
2233 struct address_space *mapping;
2234 bool dirtied;
2235 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2236
2237 dirtied = set_page_dirty(page);
2238 VM_BUG_ON_PAGE(PageAnon(page), page);
2239 /*
2240 * Take a local copy of the address_space - page.mapping may be zeroed
2241 * by truncate after unlock_page(). The address_space itself remains
2242 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2243 * release semantics to prevent the compiler from undoing this copying.
2244 */
2245 mapping = page_rmapping(page);
2246 unlock_page(page);
2247
2248 if ((dirtied || page_mkwrite) && mapping) {
2249 /*
2250 * Some device drivers do not set page.mapping
2251 * but still dirty their pages
2252 */
2253 balance_dirty_pages_ratelimited(mapping);
2254 }
2255
2256 if (!page_mkwrite)
2257 file_update_time(vma->vm_file);
2258}
2259
2260/*
2261 * Handle write page faults for pages that can be reused in the current vma
2262 *
2263 * This can happen either due to the mapping being with the VM_SHARED flag,
2264 * or due to us being the last reference standing to the page. In either
2265 * case, all we need to do here is to mark the page as writable and update
2266 * any related book-keeping.
2267 */
2268static inline void wp_page_reuse(struct vm_fault *vmf)
2269 __releases(vmf->ptl)
2270{
2271 struct vm_area_struct *vma = vmf->vma;
2272 struct page *page = vmf->page;
2273 pte_t entry;
2274 /*
2275 * Clear the pages cpupid information as the existing
2276 * information potentially belongs to a now completely
2277 * unrelated process.
2278 */
2279 if (page)
2280 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2281
2282 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2283 entry = pte_mkyoung(vmf->orig_pte);
2284 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2285 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2286 update_mmu_cache(vma, vmf->address, vmf->pte);
2287 pte_unmap_unlock(vmf->pte, vmf->ptl);
2288}
2289
2290/*
2291 * Handle the case of a page which we actually need to copy to a new page.
2292 *
2293 * Called with mmap_sem locked and the old page referenced, but
2294 * without the ptl held.
2295 *
2296 * High level logic flow:
2297 *
2298 * - Allocate a page, copy the content of the old page to the new one.
2299 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2300 * - Take the PTL. If the pte changed, bail out and release the allocated page
2301 * - If the pte is still the way we remember it, update the page table and all
2302 * relevant references. This includes dropping the reference the page-table
2303 * held to the old page, as well as updating the rmap.
2304 * - In any case, unlock the PTL and drop the reference we took to the old page.
2305 */
2306static vm_fault_t wp_page_copy(struct vm_fault *vmf)
2307{
2308 struct vm_area_struct *vma = vmf->vma;
2309 struct mm_struct *mm = vma->vm_mm;
2310 struct page *old_page = vmf->page;
2311 struct page *new_page = NULL;
2312 pte_t entry;
2313 int page_copied = 0;
2314 struct mem_cgroup *memcg;
2315 struct mmu_notifier_range range;
2316
2317 if (unlikely(anon_vma_prepare(vma)))
2318 goto oom;
2319
2320 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2321 new_page = alloc_zeroed_user_highpage_movable(vma,
2322 vmf->address);
2323 if (!new_page)
2324 goto oom;
2325 } else {
2326 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2327 vmf->address);
2328 if (!new_page)
2329 goto oom;
2330 cow_user_page(new_page, old_page, vmf->address, vma);
2331 }
2332
2333 if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))
2334 goto oom_free_new;
2335
2336 __SetPageUptodate(new_page);
2337
2338 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
2339 vmf->address & PAGE_MASK,
2340 (vmf->address & PAGE_MASK) + PAGE_SIZE);
2341 mmu_notifier_invalidate_range_start(&range);
2342
2343 /*
2344 * Re-check the pte - we dropped the lock
2345 */
2346 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2347 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2348 if (old_page) {
2349 if (!PageAnon(old_page)) {
2350 dec_mm_counter_fast(mm,
2351 mm_counter_file(old_page));
2352 inc_mm_counter_fast(mm, MM_ANONPAGES);
2353 }
2354 } else {
2355 inc_mm_counter_fast(mm, MM_ANONPAGES);
2356 }
2357 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2358 entry = mk_pte(new_page, vma->vm_page_prot);
2359 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2360 /*
2361 * Clear the pte entry and flush it first, before updating the
2362 * pte with the new entry. This will avoid a race condition
2363 * seen in the presence of one thread doing SMC and another
2364 * thread doing COW.
2365 */
2366 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2367 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2368 mem_cgroup_commit_charge(new_page, memcg, false, false);
2369 lru_cache_add_active_or_unevictable(new_page, vma);
2370 /*
2371 * We call the notify macro here because, when using secondary
2372 * mmu page tables (such as kvm shadow page tables), we want the
2373 * new page to be mapped directly into the secondary page table.
2374 */
2375 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2376 update_mmu_cache(vma, vmf->address, vmf->pte);
2377 if (old_page) {
2378 /*
2379 * Only after switching the pte to the new page may
2380 * we remove the mapcount here. Otherwise another
2381 * process may come and find the rmap count decremented
2382 * before the pte is switched to the new page, and
2383 * "reuse" the old page writing into it while our pte
2384 * here still points into it and can be read by other
2385 * threads.
2386 *
2387 * The critical issue is to order this
2388 * page_remove_rmap with the ptp_clear_flush above.
2389 * Those stores are ordered by (if nothing else,)
2390 * the barrier present in the atomic_add_negative
2391 * in page_remove_rmap.
2392 *
2393 * Then the TLB flush in ptep_clear_flush ensures that
2394 * no process can access the old page before the
2395 * decremented mapcount is visible. And the old page
2396 * cannot be reused until after the decremented
2397 * mapcount is visible. So transitively, TLBs to
2398 * old page will be flushed before it can be reused.
2399 */
2400 page_remove_rmap(old_page, false);
2401 }
2402
2403 /* Free the old page.. */
2404 new_page = old_page;
2405 page_copied = 1;
2406 } else {
2407 mem_cgroup_cancel_charge(new_page, memcg, false);
2408 }
2409
2410 if (new_page)
2411 put_page(new_page);
2412
2413 pte_unmap_unlock(vmf->pte, vmf->ptl);
2414 /*
2415 * No need to double call mmu_notifier->invalidate_range() callback as
2416 * the above ptep_clear_flush_notify() did already call it.
2417 */
2418 mmu_notifier_invalidate_range_only_end(&range);
2419 if (old_page) {
2420 /*
2421 * Don't let another task, with possibly unlocked vma,
2422 * keep the mlocked page.
2423 */
2424 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2425 lock_page(old_page); /* LRU manipulation */
2426 if (PageMlocked(old_page))
2427 munlock_vma_page(old_page);
2428 unlock_page(old_page);
2429 }
2430 put_page(old_page);
2431 }
2432 return page_copied ? VM_FAULT_WRITE : 0;
2433oom_free_new:
2434 put_page(new_page);
2435oom:
2436 if (old_page)
2437 put_page(old_page);
2438 return VM_FAULT_OOM;
2439}
2440
2441/**
2442 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2443 * writeable once the page is prepared
2444 *
2445 * @vmf: structure describing the fault
2446 *
2447 * This function handles all that is needed to finish a write page fault in a
2448 * shared mapping due to PTE being read-only once the mapped page is prepared.
2449 * It handles locking of PTE and modifying it.
2450 *
2451 * The function expects the page to be locked or other protection against
2452 * concurrent faults / writeback (such as DAX radix tree locks).
2453 *
2454 * Return: %VM_FAULT_WRITE on success, %0 when PTE got changed before
2455 * we acquired PTE lock.
2456 */
2457vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
2458{
2459 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2460 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2461 &vmf->ptl);
2462 /*
2463 * We might have raced with another page fault while we released the
2464 * pte_offset_map_lock.
2465 */
2466 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2467 pte_unmap_unlock(vmf->pte, vmf->ptl);
2468 return VM_FAULT_NOPAGE;
2469 }
2470 wp_page_reuse(vmf);
2471 return 0;
2472}
2473
2474/*
2475 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2476 * mapping
2477 */
2478static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
2479{
2480 struct vm_area_struct *vma = vmf->vma;
2481
2482 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2483 vm_fault_t ret;
2484
2485 pte_unmap_unlock(vmf->pte, vmf->ptl);
2486 vmf->flags |= FAULT_FLAG_MKWRITE;
2487 ret = vma->vm_ops->pfn_mkwrite(vmf);
2488 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2489 return ret;
2490 return finish_mkwrite_fault(vmf);
2491 }
2492 wp_page_reuse(vmf);
2493 return VM_FAULT_WRITE;
2494}
2495
2496static vm_fault_t wp_page_shared(struct vm_fault *vmf)
2497 __releases(vmf->ptl)
2498{
2499 struct vm_area_struct *vma = vmf->vma;
2500
2501 get_page(vmf->page);
2502
2503 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2504 vm_fault_t tmp;
2505
2506 pte_unmap_unlock(vmf->pte, vmf->ptl);
2507 tmp = do_page_mkwrite(vmf);
2508 if (unlikely(!tmp || (tmp &
2509 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2510 put_page(vmf->page);
2511 return tmp;
2512 }
2513 tmp = finish_mkwrite_fault(vmf);
2514 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2515 unlock_page(vmf->page);
2516 put_page(vmf->page);
2517 return tmp;
2518 }
2519 } else {
2520 wp_page_reuse(vmf);
2521 lock_page(vmf->page);
2522 }
2523 fault_dirty_shared_page(vma, vmf->page);
2524 put_page(vmf->page);
2525
2526 return VM_FAULT_WRITE;
2527}
2528
2529/*
2530 * This routine handles present pages, when users try to write
2531 * to a shared page. It is done by copying the page to a new address
2532 * and decrementing the shared-page counter for the old page.
2533 *
2534 * Note that this routine assumes that the protection checks have been
2535 * done by the caller (the low-level page fault routine in most cases).
2536 * Thus we can safely just mark it writable once we've done any necessary
2537 * COW.
2538 *
2539 * We also mark the page dirty at this point even though the page will
2540 * change only once the write actually happens. This avoids a few races,
2541 * and potentially makes it more efficient.
2542 *
2543 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2544 * but allow concurrent faults), with pte both mapped and locked.
2545 * We return with mmap_sem still held, but pte unmapped and unlocked.
2546 */
2547static vm_fault_t do_wp_page(struct vm_fault *vmf)
2548 __releases(vmf->ptl)
2549{
2550 struct vm_area_struct *vma = vmf->vma;
2551
2552 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2553 if (!vmf->page) {
2554 /*
2555 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2556 * VM_PFNMAP VMA.
2557 *
2558 * We should not cow pages in a shared writeable mapping.
2559 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2560 */
2561 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2562 (VM_WRITE|VM_SHARED))
2563 return wp_pfn_shared(vmf);
2564
2565 pte_unmap_unlock(vmf->pte, vmf->ptl);
2566 return wp_page_copy(vmf);
2567 }
2568
2569 /*
2570 * Take out anonymous pages first, anonymous shared vmas are
2571 * not dirty accountable.
2572 */
2573 if (PageAnon(vmf->page)) {
2574 int total_map_swapcount;
2575 if (PageKsm(vmf->page) && (PageSwapCache(vmf->page) ||
2576 page_count(vmf->page) != 1))
2577 goto copy;
2578 if (!trylock_page(vmf->page)) {
2579 get_page(vmf->page);
2580 pte_unmap_unlock(vmf->pte, vmf->ptl);
2581 lock_page(vmf->page);
2582 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2583 vmf->address, &vmf->ptl);
2584 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2585 unlock_page(vmf->page);
2586 pte_unmap_unlock(vmf->pte, vmf->ptl);
2587 put_page(vmf->page);
2588 return 0;
2589 }
2590 put_page(vmf->page);
2591 }
2592 if (PageKsm(vmf->page)) {
2593 bool reused = reuse_ksm_page(vmf->page, vmf->vma,
2594 vmf->address);
2595 unlock_page(vmf->page);
2596 if (!reused)
2597 goto copy;
2598 wp_page_reuse(vmf);
2599 return VM_FAULT_WRITE;
2600 }
2601 if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2602 if (total_map_swapcount == 1) {
2603 /*
2604 * The page is all ours. Move it to
2605 * our anon_vma so the rmap code will
2606 * not search our parent or siblings.
2607 * Protected against the rmap code by
2608 * the page lock.
2609 */
2610 page_move_anon_rmap(vmf->page, vma);
2611 }
2612 unlock_page(vmf->page);
2613 wp_page_reuse(vmf);
2614 return VM_FAULT_WRITE;
2615 }
2616 unlock_page(vmf->page);
2617 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2618 (VM_WRITE|VM_SHARED))) {
2619 return wp_page_shared(vmf);
2620 }
2621copy:
2622 /*
2623 * Ok, we need to copy. Oh, well..
2624 */
2625 get_page(vmf->page);
2626
2627 pte_unmap_unlock(vmf->pte, vmf->ptl);
2628 return wp_page_copy(vmf);
2629}
2630
2631static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2632 unsigned long start_addr, unsigned long end_addr,
2633 struct zap_details *details)
2634{
2635 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2636}
2637
2638static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2639 struct zap_details *details)
2640{
2641 struct vm_area_struct *vma;
2642 pgoff_t vba, vea, zba, zea;
2643
2644 vma_interval_tree_foreach(vma, root,
2645 details->first_index, details->last_index) {
2646
2647 vba = vma->vm_pgoff;
2648 vea = vba + vma_pages(vma) - 1;
2649 zba = details->first_index;
2650 if (zba < vba)
2651 zba = vba;
2652 zea = details->last_index;
2653 if (zea > vea)
2654 zea = vea;
2655
2656 unmap_mapping_range_vma(vma,
2657 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2658 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2659 details);
2660 }
2661}
2662
2663/**
2664 * unmap_mapping_pages() - Unmap pages from processes.
2665 * @mapping: The address space containing pages to be unmapped.
2666 * @start: Index of first page to be unmapped.
2667 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
2668 * @even_cows: Whether to unmap even private COWed pages.
2669 *
2670 * Unmap the pages in this address space from any userspace process which
2671 * has them mmaped. Generally, you want to remove COWed pages as well when
2672 * a file is being truncated, but not when invalidating pages from the page
2673 * cache.
2674 */
2675void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
2676 pgoff_t nr, bool even_cows)
2677{
2678 struct zap_details details = { };
2679
2680 details.check_mapping = even_cows ? NULL : mapping;
2681 details.first_index = start;
2682 details.last_index = start + nr - 1;
2683 if (details.last_index < details.first_index)
2684 details.last_index = ULONG_MAX;
2685
2686 i_mmap_lock_write(mapping);
2687 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2688 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2689 i_mmap_unlock_write(mapping);
2690}
2691
2692/**
2693 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2694 * address_space corresponding to the specified byte range in the underlying
2695 * file.
2696 *
2697 * @mapping: the address space containing mmaps to be unmapped.
2698 * @holebegin: byte in first page to unmap, relative to the start of
2699 * the underlying file. This will be rounded down to a PAGE_SIZE
2700 * boundary. Note that this is different from truncate_pagecache(), which
2701 * must keep the partial page. In contrast, we must get rid of
2702 * partial pages.
2703 * @holelen: size of prospective hole in bytes. This will be rounded
2704 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2705 * end of the file.
2706 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2707 * but 0 when invalidating pagecache, don't throw away private data.
2708 */
2709void unmap_mapping_range(struct address_space *mapping,
2710 loff_t const holebegin, loff_t const holelen, int even_cows)
2711{
2712 pgoff_t hba = holebegin >> PAGE_SHIFT;
2713 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2714
2715 /* Check for overflow. */
2716 if (sizeof(holelen) > sizeof(hlen)) {
2717 long long holeend =
2718 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2719 if (holeend & ~(long long)ULONG_MAX)
2720 hlen = ULONG_MAX - hba + 1;
2721 }
2722
2723 unmap_mapping_pages(mapping, hba, hlen, even_cows);
2724}
2725EXPORT_SYMBOL(unmap_mapping_range);
2726
2727/*
2728 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2729 * but allow concurrent faults), and pte mapped but not yet locked.
2730 * We return with pte unmapped and unlocked.
2731 *
2732 * We return with the mmap_sem locked or unlocked in the same cases
2733 * as does filemap_fault().
2734 */
2735vm_fault_t do_swap_page(struct vm_fault *vmf)
2736{
2737 struct vm_area_struct *vma = vmf->vma;
2738 struct page *page = NULL, *swapcache;
2739 struct mem_cgroup *memcg;
2740 swp_entry_t entry;
2741 pte_t pte;
2742 int locked;
2743 int exclusive = 0;
2744 vm_fault_t ret = 0;
2745
2746 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2747 goto out;
2748
2749 entry = pte_to_swp_entry(vmf->orig_pte);
2750 if (unlikely(non_swap_entry(entry))) {
2751 if (is_migration_entry(entry)) {
2752 migration_entry_wait(vma->vm_mm, vmf->pmd,
2753 vmf->address);
2754 } else if (is_device_private_entry(entry)) {
2755 vmf->page = device_private_entry_to_page(entry);
2756 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
2757 } else if (is_hwpoison_entry(entry)) {
2758 ret = VM_FAULT_HWPOISON;
2759 } else {
2760 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2761 ret = VM_FAULT_SIGBUS;
2762 }
2763 goto out;
2764 }
2765
2766
2767 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2768 page = lookup_swap_cache(entry, vma, vmf->address);
2769 swapcache = page;
2770
2771 if (!page) {
2772 struct swap_info_struct *si = swp_swap_info(entry);
2773
2774 if (si->flags & SWP_SYNCHRONOUS_IO &&
2775 __swap_count(entry) == 1) {
2776 /* skip swapcache */
2777 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2778 vmf->address);
2779 if (page) {
2780 __SetPageLocked(page);
2781 __SetPageSwapBacked(page);
2782 set_page_private(page, entry.val);
2783 lru_cache_add_anon(page);
2784 swap_readpage(page, true);
2785 }
2786 } else {
2787 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
2788 vmf);
2789 swapcache = page;
2790 }
2791
2792 if (!page) {
2793 /*
2794 * Back out if somebody else faulted in this pte
2795 * while we released the pte lock.
2796 */
2797 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2798 vmf->address, &vmf->ptl);
2799 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2800 ret = VM_FAULT_OOM;
2801 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2802 goto unlock;
2803 }
2804
2805 /* Had to read the page from swap area: Major fault */
2806 ret = VM_FAULT_MAJOR;
2807 count_vm_event(PGMAJFAULT);
2808 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2809 } else if (PageHWPoison(page)) {
2810 /*
2811 * hwpoisoned dirty swapcache pages are kept for killing
2812 * owner processes (which may be unknown at hwpoison time)
2813 */
2814 ret = VM_FAULT_HWPOISON;
2815 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2816 goto out_release;
2817 }
2818
2819 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2820
2821 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2822 if (!locked) {
2823 ret |= VM_FAULT_RETRY;
2824 goto out_release;
2825 }
2826
2827 /*
2828 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2829 * release the swapcache from under us. The page pin, and pte_same
2830 * test below, are not enough to exclude that. Even if it is still
2831 * swapcache, we need to check that the page's swap has not changed.
2832 */
2833 if (unlikely((!PageSwapCache(page) ||
2834 page_private(page) != entry.val)) && swapcache)
2835 goto out_page;
2836
2837 page = ksm_might_need_to_copy(page, vma, vmf->address);
2838 if (unlikely(!page)) {
2839 ret = VM_FAULT_OOM;
2840 page = swapcache;
2841 goto out_page;
2842 }
2843
2844 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL,
2845 &memcg, false)) {
2846 ret = VM_FAULT_OOM;
2847 goto out_page;
2848 }
2849
2850 /*
2851 * Back out if somebody else already faulted in this pte.
2852 */
2853 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2854 &vmf->ptl);
2855 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2856 goto out_nomap;
2857
2858 if (unlikely(!PageUptodate(page))) {
2859 ret = VM_FAULT_SIGBUS;
2860 goto out_nomap;
2861 }
2862
2863 /*
2864 * The page isn't present yet, go ahead with the fault.
2865 *
2866 * Be careful about the sequence of operations here.
2867 * To get its accounting right, reuse_swap_page() must be called
2868 * while the page is counted on swap but not yet in mapcount i.e.
2869 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2870 * must be called after the swap_free(), or it will never succeed.
2871 */
2872
2873 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2874 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2875 pte = mk_pte(page, vma->vm_page_prot);
2876 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2877 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2878 vmf->flags &= ~FAULT_FLAG_WRITE;
2879 ret |= VM_FAULT_WRITE;
2880 exclusive = RMAP_EXCLUSIVE;
2881 }
2882 flush_icache_page(vma, page);
2883 if (pte_swp_soft_dirty(vmf->orig_pte))
2884 pte = pte_mksoft_dirty(pte);
2885 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
2886 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
2887 vmf->orig_pte = pte;
2888
2889 /* ksm created a completely new copy */
2890 if (unlikely(page != swapcache && swapcache)) {
2891 page_add_new_anon_rmap(page, vma, vmf->address, false);
2892 mem_cgroup_commit_charge(page, memcg, false, false);
2893 lru_cache_add_active_or_unevictable(page, vma);
2894 } else {
2895 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2896 mem_cgroup_commit_charge(page, memcg, true, false);
2897 activate_page(page);
2898 }
2899
2900 swap_free(entry);
2901 if (mem_cgroup_swap_full(page) ||
2902 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2903 try_to_free_swap(page);
2904 unlock_page(page);
2905 if (page != swapcache && swapcache) {
2906 /*
2907 * Hold the lock to avoid the swap entry to be reused
2908 * until we take the PT lock for the pte_same() check
2909 * (to avoid false positives from pte_same). For
2910 * further safety release the lock after the swap_free
2911 * so that the swap count won't change under a
2912 * parallel locked swapcache.
2913 */
2914 unlock_page(swapcache);
2915 put_page(swapcache);
2916 }
2917
2918 if (vmf->flags & FAULT_FLAG_WRITE) {
2919 ret |= do_wp_page(vmf);
2920 if (ret & VM_FAULT_ERROR)
2921 ret &= VM_FAULT_ERROR;
2922 goto out;
2923 }
2924
2925 /* No need to invalidate - it was non-present before */
2926 update_mmu_cache(vma, vmf->address, vmf->pte);
2927unlock:
2928 pte_unmap_unlock(vmf->pte, vmf->ptl);
2929out:
2930 return ret;
2931out_nomap:
2932 mem_cgroup_cancel_charge(page, memcg, false);
2933 pte_unmap_unlock(vmf->pte, vmf->ptl);
2934out_page:
2935 unlock_page(page);
2936out_release:
2937 put_page(page);
2938 if (page != swapcache && swapcache) {
2939 unlock_page(swapcache);
2940 put_page(swapcache);
2941 }
2942 return ret;
2943}
2944
2945/*
2946 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2947 * but allow concurrent faults), and pte mapped but not yet locked.
2948 * We return with mmap_sem still held, but pte unmapped and unlocked.
2949 */
2950static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
2951{
2952 struct vm_area_struct *vma = vmf->vma;
2953 struct mem_cgroup *memcg;
2954 struct page *page;
2955 vm_fault_t ret = 0;
2956 pte_t entry;
2957
2958 /* File mapping without ->vm_ops ? */
2959 if (vma->vm_flags & VM_SHARED)
2960 return VM_FAULT_SIGBUS;
2961
2962 /*
2963 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2964 * pte_offset_map() on pmds where a huge pmd might be created
2965 * from a different thread.
2966 *
2967 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2968 * parallel threads are excluded by other means.
2969 *
2970 * Here we only have down_read(mmap_sem).
2971 */
2972 if (pte_alloc(vma->vm_mm, vmf->pmd))
2973 return VM_FAULT_OOM;
2974
2975 /* See the comment in pte_alloc_one_map() */
2976 if (unlikely(pmd_trans_unstable(vmf->pmd)))
2977 return 0;
2978
2979 /* Use the zero-page for reads */
2980 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
2981 !mm_forbids_zeropage(vma->vm_mm)) {
2982 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
2983 vma->vm_page_prot));
2984 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2985 vmf->address, &vmf->ptl);
2986 if (!pte_none(*vmf->pte))
2987 goto unlock;
2988 ret = check_stable_address_space(vma->vm_mm);
2989 if (ret)
2990 goto unlock;
2991 /* Deliver the page fault to userland, check inside PT lock */
2992 if (userfaultfd_missing(vma)) {
2993 pte_unmap_unlock(vmf->pte, vmf->ptl);
2994 return handle_userfault(vmf, VM_UFFD_MISSING);
2995 }
2996 goto setpte;
2997 }
2998
2999 /* Allocate our own private page. */
3000 if (unlikely(anon_vma_prepare(vma)))
3001 goto oom;
3002 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3003 if (!page)
3004 goto oom;
3005
3006 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL, &memcg,
3007 false))
3008 goto oom_free_page;
3009
3010 /*
3011 * The memory barrier inside __SetPageUptodate makes sure that
3012 * preceeding stores to the page contents become visible before
3013 * the set_pte_at() write.
3014 */
3015 __SetPageUptodate(page);
3016
3017 entry = mk_pte(page, vma->vm_page_prot);
3018 if (vma->vm_flags & VM_WRITE)
3019 entry = pte_mkwrite(pte_mkdirty(entry));
3020
3021 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3022 &vmf->ptl);
3023 if (!pte_none(*vmf->pte))
3024 goto release;
3025
3026 ret = check_stable_address_space(vma->vm_mm);
3027 if (ret)
3028 goto release;
3029
3030 /* Deliver the page fault to userland, check inside PT lock */
3031 if (userfaultfd_missing(vma)) {
3032 pte_unmap_unlock(vmf->pte, vmf->ptl);
3033 mem_cgroup_cancel_charge(page, memcg, false);
3034 put_page(page);
3035 return handle_userfault(vmf, VM_UFFD_MISSING);
3036 }
3037
3038 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3039 page_add_new_anon_rmap(page, vma, vmf->address, false);
3040 mem_cgroup_commit_charge(page, memcg, false, false);
3041 lru_cache_add_active_or_unevictable(page, vma);
3042setpte:
3043 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3044
3045 /* No need to invalidate - it was non-present before */
3046 update_mmu_cache(vma, vmf->address, vmf->pte);
3047unlock:
3048 pte_unmap_unlock(vmf->pte, vmf->ptl);
3049 return ret;
3050release:
3051 mem_cgroup_cancel_charge(page, memcg, false);
3052 put_page(page);
3053 goto unlock;
3054oom_free_page:
3055 put_page(page);
3056oom:
3057 return VM_FAULT_OOM;
3058}
3059
3060/*
3061 * The mmap_sem must have been held on entry, and may have been
3062 * released depending on flags and vma->vm_ops->fault() return value.
3063 * See filemap_fault() and __lock_page_retry().
3064 */
3065static vm_fault_t __do_fault(struct vm_fault *vmf)
3066{
3067 struct vm_area_struct *vma = vmf->vma;
3068 vm_fault_t ret;
3069
3070 /*
3071 * Preallocate pte before we take page_lock because this might lead to
3072 * deadlocks for memcg reclaim which waits for pages under writeback:
3073 * lock_page(A)
3074 * SetPageWriteback(A)
3075 * unlock_page(A)
3076 * lock_page(B)
3077 * lock_page(B)
3078 * pte_alloc_pne
3079 * shrink_page_list
3080 * wait_on_page_writeback(A)
3081 * SetPageWriteback(B)
3082 * unlock_page(B)
3083 * # flush A, B to clear the writeback
3084 */
3085 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
3086 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
3087 if (!vmf->prealloc_pte)
3088 return VM_FAULT_OOM;
3089 smp_wmb(); /* See comment in __pte_alloc() */
3090 }
3091
3092 ret = vma->vm_ops->fault(vmf);
3093 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3094 VM_FAULT_DONE_COW)))
3095 return ret;
3096
3097 if (unlikely(PageHWPoison(vmf->page))) {
3098 if (ret & VM_FAULT_LOCKED)
3099 unlock_page(vmf->page);
3100 put_page(vmf->page);
3101 vmf->page = NULL;
3102 return VM_FAULT_HWPOISON;
3103 }
3104
3105 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3106 lock_page(vmf->page);
3107 else
3108 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3109
3110 return ret;
3111}
3112
3113/*
3114 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3115 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3116 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3117 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3118 */
3119static int pmd_devmap_trans_unstable(pmd_t *pmd)
3120{
3121 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3122}
3123
3124static vm_fault_t pte_alloc_one_map(struct vm_fault *vmf)
3125{
3126 struct vm_area_struct *vma = vmf->vma;
3127
3128 if (!pmd_none(*vmf->pmd))
3129 goto map_pte;
3130 if (vmf->prealloc_pte) {
3131 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3132 if (unlikely(!pmd_none(*vmf->pmd))) {
3133 spin_unlock(vmf->ptl);
3134 goto map_pte;
3135 }
3136
3137 mm_inc_nr_ptes(vma->vm_mm);
3138 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3139 spin_unlock(vmf->ptl);
3140 vmf->prealloc_pte = NULL;
3141 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) {
3142 return VM_FAULT_OOM;
3143 }
3144map_pte:
3145 /*
3146 * If a huge pmd materialized under us just retry later. Use
3147 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3148 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3149 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3150 * running immediately after a huge pmd fault in a different thread of
3151 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3152 * All we have to ensure is that it is a regular pmd that we can walk
3153 * with pte_offset_map() and we can do that through an atomic read in
3154 * C, which is what pmd_trans_unstable() provides.
3155 */
3156 if (pmd_devmap_trans_unstable(vmf->pmd))
3157 return VM_FAULT_NOPAGE;
3158
3159 /*
3160 * At this point we know that our vmf->pmd points to a page of ptes
3161 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3162 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3163 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3164 * be valid and we will re-check to make sure the vmf->pte isn't
3165 * pte_none() under vmf->ptl protection when we return to
3166 * alloc_set_pte().
3167 */
3168 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3169 &vmf->ptl);
3170 return 0;
3171}
3172
3173#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3174static void deposit_prealloc_pte(struct vm_fault *vmf)
3175{
3176 struct vm_area_struct *vma = vmf->vma;
3177
3178 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3179 /*
3180 * We are going to consume the prealloc table,
3181 * count that as nr_ptes.
3182 */
3183 mm_inc_nr_ptes(vma->vm_mm);
3184 vmf->prealloc_pte = NULL;
3185}
3186
3187static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3188{
3189 struct vm_area_struct *vma = vmf->vma;
3190 bool write = vmf->flags & FAULT_FLAG_WRITE;
3191 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3192 pmd_t entry;
3193 int i;
3194 vm_fault_t ret;
3195
3196 if (!transhuge_vma_suitable(vma, haddr))
3197 return VM_FAULT_FALLBACK;
3198
3199 ret = VM_FAULT_FALLBACK;
3200 page = compound_head(page);
3201
3202 /*
3203 * Archs like ppc64 need additonal space to store information
3204 * related to pte entry. Use the preallocated table for that.
3205 */
3206 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3207 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3208 if (!vmf->prealloc_pte)
3209 return VM_FAULT_OOM;
3210 smp_wmb(); /* See comment in __pte_alloc() */
3211 }
3212
3213 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3214 if (unlikely(!pmd_none(*vmf->pmd)))
3215 goto out;
3216
3217 for (i = 0; i < HPAGE_PMD_NR; i++)
3218 flush_icache_page(vma, page + i);
3219
3220 entry = mk_huge_pmd(page, vma->vm_page_prot);
3221 if (write)
3222 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3223
3224 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
3225 page_add_file_rmap(page, true);
3226 /*
3227 * deposit and withdraw with pmd lock held
3228 */
3229 if (arch_needs_pgtable_deposit())
3230 deposit_prealloc_pte(vmf);
3231
3232 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3233
3234 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3235
3236 /* fault is handled */
3237 ret = 0;
3238 count_vm_event(THP_FILE_MAPPED);
3239out:
3240 spin_unlock(vmf->ptl);
3241 return ret;
3242}
3243#else
3244static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3245{
3246 BUILD_BUG();
3247 return 0;
3248}
3249#endif
3250
3251/**
3252 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3253 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3254 *
3255 * @vmf: fault environment
3256 * @memcg: memcg to charge page (only for private mappings)
3257 * @page: page to map
3258 *
3259 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3260 * return.
3261 *
3262 * Target users are page handler itself and implementations of
3263 * vm_ops->map_pages.
3264 *
3265 * Return: %0 on success, %VM_FAULT_ code in case of error.
3266 */
3267vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3268 struct page *page)
3269{
3270 struct vm_area_struct *vma = vmf->vma;
3271 bool write = vmf->flags & FAULT_FLAG_WRITE;
3272 pte_t entry;
3273 vm_fault_t ret;
3274
3275 if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3276 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3277 /* THP on COW? */
3278 VM_BUG_ON_PAGE(memcg, page);
3279
3280 ret = do_set_pmd(vmf, page);
3281 if (ret != VM_FAULT_FALLBACK)
3282 return ret;
3283 }
3284
3285 if (!vmf->pte) {
3286 ret = pte_alloc_one_map(vmf);
3287 if (ret)
3288 return ret;
3289 }
3290
3291 /* Re-check under ptl */
3292 if (unlikely(!pte_none(*vmf->pte)))
3293 return VM_FAULT_NOPAGE;
3294
3295 flush_icache_page(vma, page);
3296 entry = mk_pte(page, vma->vm_page_prot);
3297 if (write)
3298 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3299 /* copy-on-write page */
3300 if (write && !(vma->vm_flags & VM_SHARED)) {
3301 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3302 page_add_new_anon_rmap(page, vma, vmf->address, false);
3303 mem_cgroup_commit_charge(page, memcg, false, false);
3304 lru_cache_add_active_or_unevictable(page, vma);
3305 } else {
3306 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3307 page_add_file_rmap(page, false);
3308 }
3309 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3310
3311 /* no need to invalidate: a not-present page won't be cached */
3312 update_mmu_cache(vma, vmf->address, vmf->pte);
3313
3314 return 0;
3315}
3316
3317
3318/**
3319 * finish_fault - finish page fault once we have prepared the page to fault
3320 *
3321 * @vmf: structure describing the fault
3322 *
3323 * This function handles all that is needed to finish a page fault once the
3324 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3325 * given page, adds reverse page mapping, handles memcg charges and LRU
3326 * addition.
3327 *
3328 * The function expects the page to be locked and on success it consumes a
3329 * reference of a page being mapped (for the PTE which maps it).
3330 *
3331 * Return: %0 on success, %VM_FAULT_ code in case of error.
3332 */
3333vm_fault_t finish_fault(struct vm_fault *vmf)
3334{
3335 struct page *page;
3336 vm_fault_t ret = 0;
3337
3338 /* Did we COW the page? */
3339 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3340 !(vmf->vma->vm_flags & VM_SHARED))
3341 page = vmf->cow_page;
3342 else
3343 page = vmf->page;
3344
3345 /*
3346 * check even for read faults because we might have lost our CoWed
3347 * page
3348 */
3349 if (!(vmf->vma->vm_flags & VM_SHARED))
3350 ret = check_stable_address_space(vmf->vma->vm_mm);
3351 if (!ret)
3352 ret = alloc_set_pte(vmf, vmf->memcg, page);
3353 if (vmf->pte)
3354 pte_unmap_unlock(vmf->pte, vmf->ptl);
3355 return ret;
3356}
3357
3358static unsigned long fault_around_bytes __read_mostly =
3359 rounddown_pow_of_two(65536);
3360
3361#ifdef CONFIG_DEBUG_FS
3362static int fault_around_bytes_get(void *data, u64 *val)
3363{
3364 *val = fault_around_bytes;
3365 return 0;
3366}
3367
3368/*
3369 * fault_around_bytes must be rounded down to the nearest page order as it's
3370 * what do_fault_around() expects to see.
3371 */
3372static int fault_around_bytes_set(void *data, u64 val)
3373{
3374 if (val / PAGE_SIZE > PTRS_PER_PTE)
3375 return -EINVAL;
3376 if (val > PAGE_SIZE)
3377 fault_around_bytes = rounddown_pow_of_two(val);
3378 else
3379 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3380 return 0;
3381}
3382DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3383 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3384
3385static int __init fault_around_debugfs(void)
3386{
3387 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3388 &fault_around_bytes_fops);
3389 return 0;
3390}
3391late_initcall(fault_around_debugfs);
3392#endif
3393
3394/*
3395 * do_fault_around() tries to map few pages around the fault address. The hope
3396 * is that the pages will be needed soon and this will lower the number of
3397 * faults to handle.
3398 *
3399 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3400 * not ready to be mapped: not up-to-date, locked, etc.
3401 *
3402 * This function is called with the page table lock taken. In the split ptlock
3403 * case the page table lock only protects only those entries which belong to
3404 * the page table corresponding to the fault address.
3405 *
3406 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3407 * only once.
3408 *
3409 * fault_around_bytes defines how many bytes we'll try to map.
3410 * do_fault_around() expects it to be set to a power of two less than or equal
3411 * to PTRS_PER_PTE.
3412 *
3413 * The virtual address of the area that we map is naturally aligned to
3414 * fault_around_bytes rounded down to the machine page size
3415 * (and therefore to page order). This way it's easier to guarantee
3416 * that we don't cross page table boundaries.
3417 */
3418static vm_fault_t do_fault_around(struct vm_fault *vmf)
3419{
3420 unsigned long address = vmf->address, nr_pages, mask;
3421 pgoff_t start_pgoff = vmf->pgoff;
3422 pgoff_t end_pgoff;
3423 int off;
3424 vm_fault_t ret = 0;
3425
3426 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3427 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3428
3429 vmf->address = max(address & mask, vmf->vma->vm_start);
3430 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3431 start_pgoff -= off;
3432
3433 /*
3434 * end_pgoff is either the end of the page table, the end of
3435 * the vma or nr_pages from start_pgoff, depending what is nearest.
3436 */
3437 end_pgoff = start_pgoff -
3438 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3439 PTRS_PER_PTE - 1;
3440 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3441 start_pgoff + nr_pages - 1);
3442
3443 if (pmd_none(*vmf->pmd)) {
3444 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
3445 if (!vmf->prealloc_pte)
3446 goto out;
3447 smp_wmb(); /* See comment in __pte_alloc() */
3448 }
3449
3450 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3451
3452 /* Huge page is mapped? Page fault is solved */
3453 if (pmd_trans_huge(*vmf->pmd)) {
3454 ret = VM_FAULT_NOPAGE;
3455 goto out;
3456 }
3457
3458 /* ->map_pages() haven't done anything useful. Cold page cache? */
3459 if (!vmf->pte)
3460 goto out;
3461
3462 /* check if the page fault is solved */
3463 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3464 if (!pte_none(*vmf->pte))
3465 ret = VM_FAULT_NOPAGE;
3466 pte_unmap_unlock(vmf->pte, vmf->ptl);
3467out:
3468 vmf->address = address;
3469 vmf->pte = NULL;
3470 return ret;
3471}
3472
3473static vm_fault_t do_read_fault(struct vm_fault *vmf)
3474{
3475 struct vm_area_struct *vma = vmf->vma;
3476 vm_fault_t ret = 0;
3477
3478 /*
3479 * Let's call ->map_pages() first and use ->fault() as fallback
3480 * if page by the offset is not ready to be mapped (cold cache or
3481 * something).
3482 */
3483 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3484 ret = do_fault_around(vmf);
3485 if (ret)
3486 return ret;
3487 }
3488
3489 ret = __do_fault(vmf);
3490 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3491 return ret;
3492
3493 ret |= finish_fault(vmf);
3494 unlock_page(vmf->page);
3495 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3496 put_page(vmf->page);
3497 return ret;
3498}
3499
3500static vm_fault_t do_cow_fault(struct vm_fault *vmf)
3501{
3502 struct vm_area_struct *vma = vmf->vma;
3503 vm_fault_t ret;
3504
3505 if (unlikely(anon_vma_prepare(vma)))
3506 return VM_FAULT_OOM;
3507
3508 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3509 if (!vmf->cow_page)
3510 return VM_FAULT_OOM;
3511
3512 if (mem_cgroup_try_charge_delay(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3513 &vmf->memcg, false)) {
3514 put_page(vmf->cow_page);
3515 return VM_FAULT_OOM;
3516 }
3517
3518 ret = __do_fault(vmf);
3519 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3520 goto uncharge_out;
3521 if (ret & VM_FAULT_DONE_COW)
3522 return ret;
3523
3524 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3525 __SetPageUptodate(vmf->cow_page);
3526
3527 ret |= finish_fault(vmf);
3528 unlock_page(vmf->page);
3529 put_page(vmf->page);
3530 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3531 goto uncharge_out;
3532 return ret;
3533uncharge_out:
3534 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3535 put_page(vmf->cow_page);
3536 return ret;
3537}
3538
3539static vm_fault_t do_shared_fault(struct vm_fault *vmf)
3540{
3541 struct vm_area_struct *vma = vmf->vma;
3542 vm_fault_t ret, tmp;
3543
3544 ret = __do_fault(vmf);
3545 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3546 return ret;
3547
3548 /*
3549 * Check if the backing address space wants to know that the page is
3550 * about to become writable
3551 */
3552 if (vma->vm_ops->page_mkwrite) {
3553 unlock_page(vmf->page);
3554 tmp = do_page_mkwrite(vmf);
3555 if (unlikely(!tmp ||
3556 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3557 put_page(vmf->page);
3558 return tmp;
3559 }
3560 }
3561
3562 ret |= finish_fault(vmf);
3563 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3564 VM_FAULT_RETRY))) {
3565 unlock_page(vmf->page);
3566 put_page(vmf->page);
3567 return ret;
3568 }
3569
3570 fault_dirty_shared_page(vma, vmf->page);
3571 return ret;
3572}
3573
3574/*
3575 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3576 * but allow concurrent faults).
3577 * The mmap_sem may have been released depending on flags and our
3578 * return value. See filemap_fault() and __lock_page_or_retry().
3579 * If mmap_sem is released, vma may become invalid (for example
3580 * by other thread calling munmap()).
3581 */
3582static vm_fault_t do_fault(struct vm_fault *vmf)
3583{
3584 struct vm_area_struct *vma = vmf->vma;
3585 struct mm_struct *vm_mm = vma->vm_mm;
3586 vm_fault_t ret;
3587
3588 /*
3589 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
3590 */
3591 if (!vma->vm_ops->fault) {
3592 /*
3593 * If we find a migration pmd entry or a none pmd entry, which
3594 * should never happen, return SIGBUS
3595 */
3596 if (unlikely(!pmd_present(*vmf->pmd)))
3597 ret = VM_FAULT_SIGBUS;
3598 else {
3599 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
3600 vmf->pmd,
3601 vmf->address,
3602 &vmf->ptl);
3603 /*
3604 * Make sure this is not a temporary clearing of pte
3605 * by holding ptl and checking again. A R/M/W update
3606 * of pte involves: take ptl, clearing the pte so that
3607 * we don't have concurrent modification by hardware
3608 * followed by an update.
3609 */
3610 if (unlikely(pte_none(*vmf->pte)))
3611 ret = VM_FAULT_SIGBUS;
3612 else
3613 ret = VM_FAULT_NOPAGE;
3614
3615 pte_unmap_unlock(vmf->pte, vmf->ptl);
3616 }
3617 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
3618 ret = do_read_fault(vmf);
3619 else if (!(vma->vm_flags & VM_SHARED))
3620 ret = do_cow_fault(vmf);
3621 else
3622 ret = do_shared_fault(vmf);
3623
3624 /* preallocated pagetable is unused: free it */
3625 if (vmf->prealloc_pte) {
3626 pte_free(vm_mm, vmf->prealloc_pte);
3627 vmf->prealloc_pte = NULL;
3628 }
3629 return ret;
3630}
3631
3632static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3633 unsigned long addr, int page_nid,
3634 int *flags)
3635{
3636 get_page(page);
3637
3638 count_vm_numa_event(NUMA_HINT_FAULTS);
3639 if (page_nid == numa_node_id()) {
3640 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3641 *flags |= TNF_FAULT_LOCAL;
3642 }
3643
3644 return mpol_misplaced(page, vma, addr);
3645}
3646
3647static vm_fault_t do_numa_page(struct vm_fault *vmf)
3648{
3649 struct vm_area_struct *vma = vmf->vma;
3650 struct page *page = NULL;
3651 int page_nid = NUMA_NO_NODE;
3652 int last_cpupid;
3653 int target_nid;
3654 bool migrated = false;
3655 pte_t pte, old_pte;
3656 bool was_writable = pte_savedwrite(vmf->orig_pte);
3657 int flags = 0;
3658
3659 /*
3660 * The "pte" at this point cannot be used safely without
3661 * validation through pte_unmap_same(). It's of NUMA type but
3662 * the pfn may be screwed if the read is non atomic.
3663 */
3664 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3665 spin_lock(vmf->ptl);
3666 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3667 pte_unmap_unlock(vmf->pte, vmf->ptl);
3668 goto out;
3669 }
3670
3671 /*
3672 * Make it present again, Depending on how arch implementes non
3673 * accessible ptes, some can allow access by kernel mode.
3674 */
3675 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
3676 pte = pte_modify(old_pte, vma->vm_page_prot);
3677 pte = pte_mkyoung(pte);
3678 if (was_writable)
3679 pte = pte_mkwrite(pte);
3680 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
3681 update_mmu_cache(vma, vmf->address, vmf->pte);
3682
3683 page = vm_normal_page(vma, vmf->address, pte);
3684 if (!page) {
3685 pte_unmap_unlock(vmf->pte, vmf->ptl);
3686 return 0;
3687 }
3688
3689 /* TODO: handle PTE-mapped THP */
3690 if (PageCompound(page)) {
3691 pte_unmap_unlock(vmf->pte, vmf->ptl);
3692 return 0;
3693 }
3694
3695 /*
3696 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3697 * much anyway since they can be in shared cache state. This misses
3698 * the case where a mapping is writable but the process never writes
3699 * to it but pte_write gets cleared during protection updates and
3700 * pte_dirty has unpredictable behaviour between PTE scan updates,
3701 * background writeback, dirty balancing and application behaviour.
3702 */
3703 if (!pte_write(pte))
3704 flags |= TNF_NO_GROUP;
3705
3706 /*
3707 * Flag if the page is shared between multiple address spaces. This
3708 * is later used when determining whether to group tasks together
3709 */
3710 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3711 flags |= TNF_SHARED;
3712
3713 last_cpupid = page_cpupid_last(page);
3714 page_nid = page_to_nid(page);
3715 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3716 &flags);
3717 pte_unmap_unlock(vmf->pte, vmf->ptl);
3718 if (target_nid == NUMA_NO_NODE) {
3719 put_page(page);
3720 goto out;
3721 }
3722
3723 /* Migrate to the requested node */
3724 migrated = migrate_misplaced_page(page, vma, target_nid);
3725 if (migrated) {
3726 page_nid = target_nid;
3727 flags |= TNF_MIGRATED;
3728 } else
3729 flags |= TNF_MIGRATE_FAIL;
3730
3731out:
3732 if (page_nid != NUMA_NO_NODE)
3733 task_numa_fault(last_cpupid, page_nid, 1, flags);
3734 return 0;
3735}
3736
3737static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
3738{
3739 if (vma_is_anonymous(vmf->vma))
3740 return do_huge_pmd_anonymous_page(vmf);
3741 if (vmf->vma->vm_ops->huge_fault)
3742 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3743 return VM_FAULT_FALLBACK;
3744}
3745
3746/* `inline' is required to avoid gcc 4.1.2 build error */
3747static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3748{
3749 if (vma_is_anonymous(vmf->vma))
3750 return do_huge_pmd_wp_page(vmf, orig_pmd);
3751 if (vmf->vma->vm_ops->huge_fault)
3752 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3753
3754 /* COW handled on pte level: split pmd */
3755 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3756 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3757
3758 return VM_FAULT_FALLBACK;
3759}
3760
3761static inline bool vma_is_accessible(struct vm_area_struct *vma)
3762{
3763 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3764}
3765
3766static vm_fault_t create_huge_pud(struct vm_fault *vmf)
3767{
3768#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3769 /* No support for anonymous transparent PUD pages yet */
3770 if (vma_is_anonymous(vmf->vma))
3771 return VM_FAULT_FALLBACK;
3772 if (vmf->vma->vm_ops->huge_fault)
3773 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3774#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3775 return VM_FAULT_FALLBACK;
3776}
3777
3778static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3779{
3780#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3781 /* No support for anonymous transparent PUD pages yet */
3782 if (vma_is_anonymous(vmf->vma))
3783 return VM_FAULT_FALLBACK;
3784 if (vmf->vma->vm_ops->huge_fault)
3785 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3786#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3787 return VM_FAULT_FALLBACK;
3788}
3789
3790/*
3791 * These routines also need to handle stuff like marking pages dirty
3792 * and/or accessed for architectures that don't do it in hardware (most
3793 * RISC architectures). The early dirtying is also good on the i386.
3794 *
3795 * There is also a hook called "update_mmu_cache()" that architectures
3796 * with external mmu caches can use to update those (ie the Sparc or
3797 * PowerPC hashed page tables that act as extended TLBs).
3798 *
3799 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3800 * concurrent faults).
3801 *
3802 * The mmap_sem may have been released depending on flags and our return value.
3803 * See filemap_fault() and __lock_page_or_retry().
3804 */
3805static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
3806{
3807 pte_t entry;
3808
3809 if (unlikely(pmd_none(*vmf->pmd))) {
3810 /*
3811 * Leave __pte_alloc() until later: because vm_ops->fault may
3812 * want to allocate huge page, and if we expose page table
3813 * for an instant, it will be difficult to retract from
3814 * concurrent faults and from rmap lookups.
3815 */
3816 vmf->pte = NULL;
3817 } else {
3818 /* See comment in pte_alloc_one_map() */
3819 if (pmd_devmap_trans_unstable(vmf->pmd))
3820 return 0;
3821 /*
3822 * A regular pmd is established and it can't morph into a huge
3823 * pmd from under us anymore at this point because we hold the
3824 * mmap_sem read mode and khugepaged takes it in write mode.
3825 * So now it's safe to run pte_offset_map().
3826 */
3827 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3828 vmf->orig_pte = *vmf->pte;
3829
3830 /*
3831 * some architectures can have larger ptes than wordsize,
3832 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3833 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
3834 * accesses. The code below just needs a consistent view
3835 * for the ifs and we later double check anyway with the
3836 * ptl lock held. So here a barrier will do.
3837 */
3838 barrier();
3839 if (pte_none(vmf->orig_pte)) {
3840 pte_unmap(vmf->pte);
3841 vmf->pte = NULL;
3842 }
3843 }
3844
3845 if (!vmf->pte) {
3846 if (vma_is_anonymous(vmf->vma))
3847 return do_anonymous_page(vmf);
3848 else
3849 return do_fault(vmf);
3850 }
3851
3852 if (!pte_present(vmf->orig_pte))
3853 return do_swap_page(vmf);
3854
3855 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3856 return do_numa_page(vmf);
3857
3858 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3859 spin_lock(vmf->ptl);
3860 entry = vmf->orig_pte;
3861 if (unlikely(!pte_same(*vmf->pte, entry)))
3862 goto unlock;
3863 if (vmf->flags & FAULT_FLAG_WRITE) {
3864 if (!pte_write(entry))
3865 return do_wp_page(vmf);
3866 entry = pte_mkdirty(entry);
3867 }
3868 entry = pte_mkyoung(entry);
3869 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3870 vmf->flags & FAULT_FLAG_WRITE)) {
3871 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3872 } else {
3873 /*
3874 * This is needed only for protection faults but the arch code
3875 * is not yet telling us if this is a protection fault or not.
3876 * This still avoids useless tlb flushes for .text page faults
3877 * with threads.
3878 */
3879 if (vmf->flags & FAULT_FLAG_WRITE)
3880 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3881 }
3882unlock:
3883 pte_unmap_unlock(vmf->pte, vmf->ptl);
3884 return 0;
3885}
3886
3887/*
3888 * By the time we get here, we already hold the mm semaphore
3889 *
3890 * The mmap_sem may have been released depending on flags and our
3891 * return value. See filemap_fault() and __lock_page_or_retry().
3892 */
3893static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
3894 unsigned long address, unsigned int flags)
3895{
3896 struct vm_fault vmf = {
3897 .vma = vma,
3898 .address = address & PAGE_MASK,
3899 .flags = flags,
3900 .pgoff = linear_page_index(vma, address),
3901 .gfp_mask = __get_fault_gfp_mask(vma),
3902 };
3903 unsigned int dirty = flags & FAULT_FLAG_WRITE;
3904 struct mm_struct *mm = vma->vm_mm;
3905 pgd_t *pgd;
3906 p4d_t *p4d;
3907 vm_fault_t ret;
3908
3909 pgd = pgd_offset(mm, address);
3910 p4d = p4d_alloc(mm, pgd, address);
3911 if (!p4d)
3912 return VM_FAULT_OOM;
3913
3914 vmf.pud = pud_alloc(mm, p4d, address);
3915 if (!vmf.pud)
3916 return VM_FAULT_OOM;
3917 if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
3918 ret = create_huge_pud(&vmf);
3919 if (!(ret & VM_FAULT_FALLBACK))
3920 return ret;
3921 } else {
3922 pud_t orig_pud = *vmf.pud;
3923
3924 barrier();
3925 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
3926
3927 /* NUMA case for anonymous PUDs would go here */
3928
3929 if (dirty && !pud_write(orig_pud)) {
3930 ret = wp_huge_pud(&vmf, orig_pud);
3931 if (!(ret & VM_FAULT_FALLBACK))
3932 return ret;
3933 } else {
3934 huge_pud_set_accessed(&vmf, orig_pud);
3935 return 0;
3936 }
3937 }
3938 }
3939
3940 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
3941 if (!vmf.pmd)
3942 return VM_FAULT_OOM;
3943 if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
3944 ret = create_huge_pmd(&vmf);
3945 if (!(ret & VM_FAULT_FALLBACK))
3946 return ret;
3947 } else {
3948 pmd_t orig_pmd = *vmf.pmd;
3949
3950 barrier();
3951 if (unlikely(is_swap_pmd(orig_pmd))) {
3952 VM_BUG_ON(thp_migration_supported() &&
3953 !is_pmd_migration_entry(orig_pmd));
3954 if (is_pmd_migration_entry(orig_pmd))
3955 pmd_migration_entry_wait(mm, vmf.pmd);
3956 return 0;
3957 }
3958 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3959 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
3960 return do_huge_pmd_numa_page(&vmf, orig_pmd);
3961
3962 if (dirty && !pmd_write(orig_pmd)) {
3963 ret = wp_huge_pmd(&vmf, orig_pmd);
3964 if (!(ret & VM_FAULT_FALLBACK))
3965 return ret;
3966 } else {
3967 huge_pmd_set_accessed(&vmf, orig_pmd);
3968 return 0;
3969 }
3970 }
3971 }
3972
3973 return handle_pte_fault(&vmf);
3974}
3975
3976/*
3977 * By the time we get here, we already hold the mm semaphore
3978 *
3979 * The mmap_sem may have been released depending on flags and our
3980 * return value. See filemap_fault() and __lock_page_or_retry().
3981 */
3982vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3983 unsigned int flags)
3984{
3985 vm_fault_t ret;
3986
3987 __set_current_state(TASK_RUNNING);
3988
3989 count_vm_event(PGFAULT);
3990 count_memcg_event_mm(vma->vm_mm, PGFAULT);
3991
3992 /* do counter updates before entering really critical section. */
3993 check_sync_rss_stat(current);
3994
3995 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3996 flags & FAULT_FLAG_INSTRUCTION,
3997 flags & FAULT_FLAG_REMOTE))
3998 return VM_FAULT_SIGSEGV;
3999
4000 /*
4001 * Enable the memcg OOM handling for faults triggered in user
4002 * space. Kernel faults are handled more gracefully.
4003 */
4004 if (flags & FAULT_FLAG_USER)
4005 mem_cgroup_enter_user_fault();
4006
4007 if (unlikely(is_vm_hugetlb_page(vma)))
4008 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4009 else
4010 ret = __handle_mm_fault(vma, address, flags);
4011
4012 if (flags & FAULT_FLAG_USER) {
4013 mem_cgroup_exit_user_fault();
4014 /*
4015 * The task may have entered a memcg OOM situation but
4016 * if the allocation error was handled gracefully (no
4017 * VM_FAULT_OOM), there is no need to kill anything.
4018 * Just clean up the OOM state peacefully.
4019 */
4020 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4021 mem_cgroup_oom_synchronize(false);
4022 }
4023
4024 return ret;
4025}
4026EXPORT_SYMBOL_GPL(handle_mm_fault);
4027
4028#ifndef __PAGETABLE_P4D_FOLDED
4029/*
4030 * Allocate p4d page table.
4031 * We've already handled the fast-path in-line.
4032 */
4033int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4034{
4035 p4d_t *new = p4d_alloc_one(mm, address);
4036 if (!new)
4037 return -ENOMEM;
4038
4039 smp_wmb(); /* See comment in __pte_alloc */
4040
4041 spin_lock(&mm->page_table_lock);
4042 if (pgd_present(*pgd)) /* Another has populated it */
4043 p4d_free(mm, new);
4044 else
4045 pgd_populate(mm, pgd, new);
4046 spin_unlock(&mm->page_table_lock);
4047 return 0;
4048}
4049#endif /* __PAGETABLE_P4D_FOLDED */
4050
4051#ifndef __PAGETABLE_PUD_FOLDED
4052/*
4053 * Allocate page upper directory.
4054 * We've already handled the fast-path in-line.
4055 */
4056int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4057{
4058 pud_t *new = pud_alloc_one(mm, address);
4059 if (!new)
4060 return -ENOMEM;
4061
4062 smp_wmb(); /* See comment in __pte_alloc */
4063
4064 spin_lock(&mm->page_table_lock);
4065#ifndef __ARCH_HAS_5LEVEL_HACK
4066 if (!p4d_present(*p4d)) {
4067 mm_inc_nr_puds(mm);
4068 p4d_populate(mm, p4d, new);
4069 } else /* Another has populated it */
4070 pud_free(mm, new);
4071#else
4072 if (!pgd_present(*p4d)) {
4073 mm_inc_nr_puds(mm);
4074 pgd_populate(mm, p4d, new);
4075 } else /* Another has populated it */
4076 pud_free(mm, new);
4077#endif /* __ARCH_HAS_5LEVEL_HACK */
4078 spin_unlock(&mm->page_table_lock);
4079 return 0;
4080}
4081#endif /* __PAGETABLE_PUD_FOLDED */
4082
4083#ifndef __PAGETABLE_PMD_FOLDED
4084/*
4085 * Allocate page middle directory.
4086 * We've already handled the fast-path in-line.
4087 */
4088int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4089{
4090 spinlock_t *ptl;
4091 pmd_t *new = pmd_alloc_one(mm, address);
4092 if (!new)
4093 return -ENOMEM;
4094
4095 smp_wmb(); /* See comment in __pte_alloc */
4096
4097 ptl = pud_lock(mm, pud);
4098#ifndef __ARCH_HAS_4LEVEL_HACK
4099 if (!pud_present(*pud)) {
4100 mm_inc_nr_pmds(mm);
4101 pud_populate(mm, pud, new);
4102 } else /* Another has populated it */
4103 pmd_free(mm, new);
4104#else
4105 if (!pgd_present(*pud)) {
4106 mm_inc_nr_pmds(mm);
4107 pgd_populate(mm, pud, new);
4108 } else /* Another has populated it */
4109 pmd_free(mm, new);
4110#endif /* __ARCH_HAS_4LEVEL_HACK */
4111 spin_unlock(ptl);
4112 return 0;
4113}
4114#endif /* __PAGETABLE_PMD_FOLDED */
4115
4116static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4117 struct mmu_notifier_range *range,
4118 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4119{
4120 pgd_t *pgd;
4121 p4d_t *p4d;
4122 pud_t *pud;
4123 pmd_t *pmd;
4124 pte_t *ptep;
4125
4126 pgd = pgd_offset(mm, address);
4127 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4128 goto out;
4129
4130 p4d = p4d_offset(pgd, address);
4131 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4132 goto out;
4133
4134 pud = pud_offset(p4d, address);
4135 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4136 goto out;
4137
4138 pmd = pmd_offset(pud, address);
4139 VM_BUG_ON(pmd_trans_huge(*pmd));
4140
4141 if (pmd_huge(*pmd)) {
4142 if (!pmdpp)
4143 goto out;
4144
4145 if (range) {
4146 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0,
4147 NULL, mm, address & PMD_MASK,
4148 (address & PMD_MASK) + PMD_SIZE);
4149 mmu_notifier_invalidate_range_start(range);
4150 }
4151 *ptlp = pmd_lock(mm, pmd);
4152 if (pmd_huge(*pmd)) {
4153 *pmdpp = pmd;
4154 return 0;
4155 }
4156 spin_unlock(*ptlp);
4157 if (range)
4158 mmu_notifier_invalidate_range_end(range);
4159 }
4160
4161 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4162 goto out;
4163
4164 if (range) {
4165 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
4166 address & PAGE_MASK,
4167 (address & PAGE_MASK) + PAGE_SIZE);
4168 mmu_notifier_invalidate_range_start(range);
4169 }
4170 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4171 if (!pte_present(*ptep))
4172 goto unlock;
4173 *ptepp = ptep;
4174 return 0;
4175unlock:
4176 pte_unmap_unlock(ptep, *ptlp);
4177 if (range)
4178 mmu_notifier_invalidate_range_end(range);
4179out:
4180 return -EINVAL;
4181}
4182
4183static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4184 pte_t **ptepp, spinlock_t **ptlp)
4185{
4186 int res;
4187
4188 /* (void) is needed to make gcc happy */
4189 (void) __cond_lock(*ptlp,
4190 !(res = __follow_pte_pmd(mm, address, NULL,
4191 ptepp, NULL, ptlp)));
4192 return res;
4193}
4194
4195int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4196 struct mmu_notifier_range *range,
4197 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4198{
4199 int res;
4200
4201 /* (void) is needed to make gcc happy */
4202 (void) __cond_lock(*ptlp,
4203 !(res = __follow_pte_pmd(mm, address, range,
4204 ptepp, pmdpp, ptlp)));
4205 return res;
4206}
4207EXPORT_SYMBOL(follow_pte_pmd);
4208
4209/**
4210 * follow_pfn - look up PFN at a user virtual address
4211 * @vma: memory mapping
4212 * @address: user virtual address
4213 * @pfn: location to store found PFN
4214 *
4215 * Only IO mappings and raw PFN mappings are allowed.
4216 *
4217 * Return: zero and the pfn at @pfn on success, -ve otherwise.
4218 */
4219int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4220 unsigned long *pfn)
4221{
4222 int ret = -EINVAL;
4223 spinlock_t *ptl;
4224 pte_t *ptep;
4225
4226 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4227 return ret;
4228
4229 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4230 if (ret)
4231 return ret;
4232 *pfn = pte_pfn(*ptep);
4233 pte_unmap_unlock(ptep, ptl);
4234 return 0;
4235}
4236EXPORT_SYMBOL(follow_pfn);
4237
4238#ifdef CONFIG_HAVE_IOREMAP_PROT
4239int follow_phys(struct vm_area_struct *vma,
4240 unsigned long address, unsigned int flags,
4241 unsigned long *prot, resource_size_t *phys)
4242{
4243 int ret = -EINVAL;
4244 pte_t *ptep, pte;
4245 spinlock_t *ptl;
4246
4247 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4248 goto out;
4249
4250 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4251 goto out;
4252 pte = *ptep;
4253
4254 if ((flags & FOLL_WRITE) && !pte_write(pte))
4255 goto unlock;
4256
4257 *prot = pgprot_val(pte_pgprot(pte));
4258 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4259
4260 ret = 0;
4261unlock:
4262 pte_unmap_unlock(ptep, ptl);
4263out:
4264 return ret;
4265}
4266
4267int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4268 void *buf, int len, int write)
4269{
4270 resource_size_t phys_addr;
4271 unsigned long prot = 0;
4272 void __iomem *maddr;
4273 int offset = addr & (PAGE_SIZE-1);
4274
4275 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4276 return -EINVAL;
4277
4278 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4279 if (!maddr)
4280 return -ENOMEM;
4281
4282 if (write)
4283 memcpy_toio(maddr + offset, buf, len);
4284 else
4285 memcpy_fromio(buf, maddr + offset, len);
4286 iounmap(maddr);
4287
4288 return len;
4289}
4290EXPORT_SYMBOL_GPL(generic_access_phys);
4291#endif
4292
4293/*
4294 * Access another process' address space as given in mm. If non-NULL, use the
4295 * given task for page fault accounting.
4296 */
4297int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4298 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4299{
4300 struct vm_area_struct *vma;
4301 void *old_buf = buf;
4302 int write = gup_flags & FOLL_WRITE;
4303
4304 if (down_read_killable(&mm->mmap_sem))
4305 return 0;
4306
4307 /* ignore errors, just check how much was successfully transferred */
4308 while (len) {
4309 int bytes, ret, offset;
4310 void *maddr;
4311 struct page *page = NULL;
4312
4313 ret = get_user_pages_remote(tsk, mm, addr, 1,
4314 gup_flags, &page, &vma, NULL);
4315 if (ret <= 0) {
4316#ifndef CONFIG_HAVE_IOREMAP_PROT
4317 break;
4318#else
4319 /*
4320 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4321 * we can access using slightly different code.
4322 */
4323 vma = find_vma(mm, addr);
4324 if (!vma || vma->vm_start > addr)
4325 break;
4326 if (vma->vm_ops && vma->vm_ops->access)
4327 ret = vma->vm_ops->access(vma, addr, buf,
4328 len, write);
4329 if (ret <= 0)
4330 break;
4331 bytes = ret;
4332#endif
4333 } else {
4334 bytes = len;
4335 offset = addr & (PAGE_SIZE-1);
4336 if (bytes > PAGE_SIZE-offset)
4337 bytes = PAGE_SIZE-offset;
4338
4339 maddr = kmap(page);
4340 if (write) {
4341 copy_to_user_page(vma, page, addr,
4342 maddr + offset, buf, bytes);
4343 set_page_dirty_lock(page);
4344 } else {
4345 copy_from_user_page(vma, page, addr,
4346 buf, maddr + offset, bytes);
4347 }
4348 kunmap(page);
4349 put_page(page);
4350 }
4351 len -= bytes;
4352 buf += bytes;
4353 addr += bytes;
4354 }
4355 up_read(&mm->mmap_sem);
4356
4357 return buf - old_buf;
4358}
4359
4360/**
4361 * access_remote_vm - access another process' address space
4362 * @mm: the mm_struct of the target address space
4363 * @addr: start address to access
4364 * @buf: source or destination buffer
4365 * @len: number of bytes to transfer
4366 * @gup_flags: flags modifying lookup behaviour
4367 *
4368 * The caller must hold a reference on @mm.
4369 *
4370 * Return: number of bytes copied from source to destination.
4371 */
4372int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4373 void *buf, int len, unsigned int gup_flags)
4374{
4375 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4376}
4377
4378/*
4379 * Access another process' address space.
4380 * Source/target buffer must be kernel space,
4381 * Do not walk the page table directly, use get_user_pages
4382 */
4383int access_process_vm(struct task_struct *tsk, unsigned long addr,
4384 void *buf, int len, unsigned int gup_flags)
4385{
4386 struct mm_struct *mm;
4387 int ret;
4388
4389 mm = get_task_mm(tsk);
4390 if (!mm)
4391 return 0;
4392
4393 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4394
4395 mmput(mm);
4396
4397 return ret;
4398}
4399EXPORT_SYMBOL_GPL(access_process_vm);
4400
4401/*
4402 * Print the name of a VMA.
4403 */
4404void print_vma_addr(char *prefix, unsigned long ip)
4405{
4406 struct mm_struct *mm = current->mm;
4407 struct vm_area_struct *vma;
4408
4409 /*
4410 * we might be running from an atomic context so we cannot sleep
4411 */
4412 if (!down_read_trylock(&mm->mmap_sem))
4413 return;
4414
4415 vma = find_vma(mm, ip);
4416 if (vma && vma->vm_file) {
4417 struct file *f = vma->vm_file;
4418 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4419 if (buf) {
4420 char *p;
4421
4422 p = file_path(f, buf, PAGE_SIZE);
4423 if (IS_ERR(p))
4424 p = "?";
4425 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4426 vma->vm_start,
4427 vma->vm_end - vma->vm_start);
4428 free_page((unsigned long)buf);
4429 }
4430 }
4431 up_read(&mm->mmap_sem);
4432}
4433
4434#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4435void __might_fault(const char *file, int line)
4436{
4437 /*
4438 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4439 * holding the mmap_sem, this is safe because kernel memory doesn't
4440 * get paged out, therefore we'll never actually fault, and the
4441 * below annotations will generate false positives.
4442 */
4443 if (uaccess_kernel())
4444 return;
4445 if (pagefault_disabled())
4446 return;
4447 __might_sleep(file, line, 0);
4448#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4449 if (current->mm)
4450 might_lock_read(¤t->mm->mmap_sem);
4451#endif
4452}
4453EXPORT_SYMBOL(__might_fault);
4454#endif
4455
4456#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4457/*
4458 * Process all subpages of the specified huge page with the specified
4459 * operation. The target subpage will be processed last to keep its
4460 * cache lines hot.
4461 */
4462static inline void process_huge_page(
4463 unsigned long addr_hint, unsigned int pages_per_huge_page,
4464 void (*process_subpage)(unsigned long addr, int idx, void *arg),
4465 void *arg)
4466{
4467 int i, n, base, l;
4468 unsigned long addr = addr_hint &
4469 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4470
4471 /* Process target subpage last to keep its cache lines hot */
4472 might_sleep();
4473 n = (addr_hint - addr) / PAGE_SIZE;
4474 if (2 * n <= pages_per_huge_page) {
4475 /* If target subpage in first half of huge page */
4476 base = 0;
4477 l = n;
4478 /* Process subpages at the end of huge page */
4479 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4480 cond_resched();
4481 process_subpage(addr + i * PAGE_SIZE, i, arg);
4482 }
4483 } else {
4484 /* If target subpage in second half of huge page */
4485 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4486 l = pages_per_huge_page - n;
4487 /* Process subpages at the begin of huge page */
4488 for (i = 0; i < base; i++) {
4489 cond_resched();
4490 process_subpage(addr + i * PAGE_SIZE, i, arg);
4491 }
4492 }
4493 /*
4494 * Process remaining subpages in left-right-left-right pattern
4495 * towards the target subpage
4496 */
4497 for (i = 0; i < l; i++) {
4498 int left_idx = base + i;
4499 int right_idx = base + 2 * l - 1 - i;
4500
4501 cond_resched();
4502 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
4503 cond_resched();
4504 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
4505 }
4506}
4507
4508static void clear_gigantic_page(struct page *page,
4509 unsigned long addr,
4510 unsigned int pages_per_huge_page)
4511{
4512 int i;
4513 struct page *p = page;
4514
4515 might_sleep();
4516 for (i = 0; i < pages_per_huge_page;
4517 i++, p = mem_map_next(p, page, i)) {
4518 cond_resched();
4519 clear_user_highpage(p, addr + i * PAGE_SIZE);
4520 }
4521}
4522
4523static void clear_subpage(unsigned long addr, int idx, void *arg)
4524{
4525 struct page *page = arg;
4526
4527 clear_user_highpage(page + idx, addr);
4528}
4529
4530void clear_huge_page(struct page *page,
4531 unsigned long addr_hint, unsigned int pages_per_huge_page)
4532{
4533 unsigned long addr = addr_hint &
4534 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4535
4536 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4537 clear_gigantic_page(page, addr, pages_per_huge_page);
4538 return;
4539 }
4540
4541 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
4542}
4543
4544static void copy_user_gigantic_page(struct page *dst, struct page *src,
4545 unsigned long addr,
4546 struct vm_area_struct *vma,
4547 unsigned int pages_per_huge_page)
4548{
4549 int i;
4550 struct page *dst_base = dst;
4551 struct page *src_base = src;
4552
4553 for (i = 0; i < pages_per_huge_page; ) {
4554 cond_resched();
4555 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4556
4557 i++;
4558 dst = mem_map_next(dst, dst_base, i);
4559 src = mem_map_next(src, src_base, i);
4560 }
4561}
4562
4563struct copy_subpage_arg {
4564 struct page *dst;
4565 struct page *src;
4566 struct vm_area_struct *vma;
4567};
4568
4569static void copy_subpage(unsigned long addr, int idx, void *arg)
4570{
4571 struct copy_subpage_arg *copy_arg = arg;
4572
4573 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
4574 addr, copy_arg->vma);
4575}
4576
4577void copy_user_huge_page(struct page *dst, struct page *src,
4578 unsigned long addr_hint, struct vm_area_struct *vma,
4579 unsigned int pages_per_huge_page)
4580{
4581 unsigned long addr = addr_hint &
4582 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4583 struct copy_subpage_arg arg = {
4584 .dst = dst,
4585 .src = src,
4586 .vma = vma,
4587 };
4588
4589 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4590 copy_user_gigantic_page(dst, src, addr, vma,
4591 pages_per_huge_page);
4592 return;
4593 }
4594
4595 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
4596}
4597
4598long copy_huge_page_from_user(struct page *dst_page,
4599 const void __user *usr_src,
4600 unsigned int pages_per_huge_page,
4601 bool allow_pagefault)
4602{
4603 void *src = (void *)usr_src;
4604 void *page_kaddr;
4605 unsigned long i, rc = 0;
4606 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4607
4608 for (i = 0; i < pages_per_huge_page; i++) {
4609 if (allow_pagefault)
4610 page_kaddr = kmap(dst_page + i);
4611 else
4612 page_kaddr = kmap_atomic(dst_page + i);
4613 rc = copy_from_user(page_kaddr,
4614 (const void __user *)(src + i * PAGE_SIZE),
4615 PAGE_SIZE);
4616 if (allow_pagefault)
4617 kunmap(dst_page + i);
4618 else
4619 kunmap_atomic(page_kaddr);
4620
4621 ret_val -= (PAGE_SIZE - rc);
4622 if (rc)
4623 break;
4624
4625 cond_resched();
4626 }
4627 return ret_val;
4628}
4629#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4630
4631#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4632
4633static struct kmem_cache *page_ptl_cachep;
4634
4635void __init ptlock_cache_init(void)
4636{
4637 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4638 SLAB_PANIC, NULL);
4639}
4640
4641bool ptlock_alloc(struct page *page)
4642{
4643 spinlock_t *ptl;
4644
4645 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4646 if (!ptl)
4647 return false;
4648 page->ptl = ptl;
4649 return true;
4650}
4651
4652void ptlock_free(struct page *page)
4653{
4654 kmem_cache_free(page_ptl_cachep, page->ptl);
4655}
4656#endif