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1/*
2 * linux/mm/memory.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
10 */
11
12/*
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
15 *
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
18 * far as I could see.
19 *
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21 */
22
23/*
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
29 */
30
31/*
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
34 *
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
37 *
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39 */
40
41#include <linux/kernel_stat.h>
42#include <linux/mm.h>
43#include <linux/sched/mm.h>
44#include <linux/sched/coredump.h>
45#include <linux/sched/numa_balancing.h>
46#include <linux/sched/task.h>
47#include <linux/hugetlb.h>
48#include <linux/mman.h>
49#include <linux/swap.h>
50#include <linux/highmem.h>
51#include <linux/pagemap.h>
52#include <linux/memremap.h>
53#include <linux/ksm.h>
54#include <linux/rmap.h>
55#include <linux/export.h>
56#include <linux/delayacct.h>
57#include <linux/init.h>
58#include <linux/pfn_t.h>
59#include <linux/writeback.h>
60#include <linux/memcontrol.h>
61#include <linux/mmu_notifier.h>
62#include <linux/swapops.h>
63#include <linux/elf.h>
64#include <linux/gfp.h>
65#include <linux/migrate.h>
66#include <linux/string.h>
67#include <linux/dma-debug.h>
68#include <linux/debugfs.h>
69#include <linux/userfaultfd_k.h>
70#include <linux/dax.h>
71#include <linux/oom.h>
72
73#include <asm/io.h>
74#include <asm/mmu_context.h>
75#include <asm/pgalloc.h>
76#include <linux/uaccess.h>
77#include <asm/tlb.h>
78#include <asm/tlbflush.h>
79#include <asm/pgtable.h>
80
81#include "internal.h"
82
83#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
84#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
85#endif
86
87#ifndef CONFIG_NEED_MULTIPLE_NODES
88/* use the per-pgdat data instead for discontigmem - mbligh */
89unsigned long max_mapnr;
90EXPORT_SYMBOL(max_mapnr);
91
92struct page *mem_map;
93EXPORT_SYMBOL(mem_map);
94#endif
95
96/*
97 * A number of key systems in x86 including ioremap() rely on the assumption
98 * that high_memory defines the upper bound on direct map memory, then end
99 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
100 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
101 * and ZONE_HIGHMEM.
102 */
103void *high_memory;
104EXPORT_SYMBOL(high_memory);
105
106/*
107 * Randomize the address space (stacks, mmaps, brk, etc.).
108 *
109 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
110 * as ancient (libc5 based) binaries can segfault. )
111 */
112int randomize_va_space __read_mostly =
113#ifdef CONFIG_COMPAT_BRK
114 1;
115#else
116 2;
117#endif
118
119static int __init disable_randmaps(char *s)
120{
121 randomize_va_space = 0;
122 return 1;
123}
124__setup("norandmaps", disable_randmaps);
125
126unsigned long zero_pfn __read_mostly;
127EXPORT_SYMBOL(zero_pfn);
128
129unsigned long highest_memmap_pfn __read_mostly;
130
131/*
132 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
133 */
134static int __init init_zero_pfn(void)
135{
136 zero_pfn = page_to_pfn(ZERO_PAGE(0));
137 return 0;
138}
139core_initcall(init_zero_pfn);
140
141
142#if defined(SPLIT_RSS_COUNTING)
143
144void sync_mm_rss(struct mm_struct *mm)
145{
146 int i;
147
148 for (i = 0; i < NR_MM_COUNTERS; i++) {
149 if (current->rss_stat.count[i]) {
150 add_mm_counter(mm, i, current->rss_stat.count[i]);
151 current->rss_stat.count[i] = 0;
152 }
153 }
154 current->rss_stat.events = 0;
155}
156
157static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
158{
159 struct task_struct *task = current;
160
161 if (likely(task->mm == mm))
162 task->rss_stat.count[member] += val;
163 else
164 add_mm_counter(mm, member, val);
165}
166#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
167#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
168
169/* sync counter once per 64 page faults */
170#define TASK_RSS_EVENTS_THRESH (64)
171static void check_sync_rss_stat(struct task_struct *task)
172{
173 if (unlikely(task != current))
174 return;
175 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
176 sync_mm_rss(task->mm);
177}
178#else /* SPLIT_RSS_COUNTING */
179
180#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
181#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
182
183static void check_sync_rss_stat(struct task_struct *task)
184{
185}
186
187#endif /* SPLIT_RSS_COUNTING */
188
189#ifdef HAVE_GENERIC_MMU_GATHER
190
191static bool tlb_next_batch(struct mmu_gather *tlb)
192{
193 struct mmu_gather_batch *batch;
194
195 batch = tlb->active;
196 if (batch->next) {
197 tlb->active = batch->next;
198 return true;
199 }
200
201 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
202 return false;
203
204 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
205 if (!batch)
206 return false;
207
208 tlb->batch_count++;
209 batch->next = NULL;
210 batch->nr = 0;
211 batch->max = MAX_GATHER_BATCH;
212
213 tlb->active->next = batch;
214 tlb->active = batch;
215
216 return true;
217}
218
219void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
220 unsigned long start, unsigned long end)
221{
222 tlb->mm = mm;
223
224 /* Is it from 0 to ~0? */
225 tlb->fullmm = !(start | (end+1));
226 tlb->need_flush_all = 0;
227 tlb->local.next = NULL;
228 tlb->local.nr = 0;
229 tlb->local.max = ARRAY_SIZE(tlb->__pages);
230 tlb->active = &tlb->local;
231 tlb->batch_count = 0;
232
233#ifdef CONFIG_HAVE_RCU_TABLE_FREE
234 tlb->batch = NULL;
235#endif
236 tlb->page_size = 0;
237
238 __tlb_reset_range(tlb);
239}
240
241static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
242{
243 if (!tlb->end)
244 return;
245
246 tlb_flush(tlb);
247 mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
248#ifdef CONFIG_HAVE_RCU_TABLE_FREE
249 tlb_table_flush(tlb);
250#endif
251 __tlb_reset_range(tlb);
252}
253
254static void tlb_flush_mmu_free(struct mmu_gather *tlb)
255{
256 struct mmu_gather_batch *batch;
257
258 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
259 free_pages_and_swap_cache(batch->pages, batch->nr);
260 batch->nr = 0;
261 }
262 tlb->active = &tlb->local;
263}
264
265void tlb_flush_mmu(struct mmu_gather *tlb)
266{
267 tlb_flush_mmu_tlbonly(tlb);
268 tlb_flush_mmu_free(tlb);
269}
270
271/* tlb_finish_mmu
272 * Called at the end of the shootdown operation to free up any resources
273 * that were required.
274 */
275void arch_tlb_finish_mmu(struct mmu_gather *tlb,
276 unsigned long start, unsigned long end, bool force)
277{
278 struct mmu_gather_batch *batch, *next;
279
280 if (force)
281 __tlb_adjust_range(tlb, start, end - start);
282
283 tlb_flush_mmu(tlb);
284
285 /* keep the page table cache within bounds */
286 check_pgt_cache();
287
288 for (batch = tlb->local.next; batch; batch = next) {
289 next = batch->next;
290 free_pages((unsigned long)batch, 0);
291 }
292 tlb->local.next = NULL;
293}
294
295/* __tlb_remove_page
296 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
297 * handling the additional races in SMP caused by other CPUs caching valid
298 * mappings in their TLBs. Returns the number of free page slots left.
299 * When out of page slots we must call tlb_flush_mmu().
300 *returns true if the caller should flush.
301 */
302bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
303{
304 struct mmu_gather_batch *batch;
305
306 VM_BUG_ON(!tlb->end);
307 VM_WARN_ON(tlb->page_size != page_size);
308
309 batch = tlb->active;
310 /*
311 * Add the page and check if we are full. If so
312 * force a flush.
313 */
314 batch->pages[batch->nr++] = page;
315 if (batch->nr == batch->max) {
316 if (!tlb_next_batch(tlb))
317 return true;
318 batch = tlb->active;
319 }
320 VM_BUG_ON_PAGE(batch->nr > batch->max, page);
321
322 return false;
323}
324
325#endif /* HAVE_GENERIC_MMU_GATHER */
326
327#ifdef CONFIG_HAVE_RCU_TABLE_FREE
328
329/*
330 * See the comment near struct mmu_table_batch.
331 */
332
333static void tlb_remove_table_smp_sync(void *arg)
334{
335 /* Simply deliver the interrupt */
336}
337
338static void tlb_remove_table_one(void *table)
339{
340 /*
341 * This isn't an RCU grace period and hence the page-tables cannot be
342 * assumed to be actually RCU-freed.
343 *
344 * It is however sufficient for software page-table walkers that rely on
345 * IRQ disabling. See the comment near struct mmu_table_batch.
346 */
347 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
348 __tlb_remove_table(table);
349}
350
351static void tlb_remove_table_rcu(struct rcu_head *head)
352{
353 struct mmu_table_batch *batch;
354 int i;
355
356 batch = container_of(head, struct mmu_table_batch, rcu);
357
358 for (i = 0; i < batch->nr; i++)
359 __tlb_remove_table(batch->tables[i]);
360
361 free_page((unsigned long)batch);
362}
363
364void tlb_table_flush(struct mmu_gather *tlb)
365{
366 struct mmu_table_batch **batch = &tlb->batch;
367
368 if (*batch) {
369 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
370 *batch = NULL;
371 }
372}
373
374void tlb_remove_table(struct mmu_gather *tlb, void *table)
375{
376 struct mmu_table_batch **batch = &tlb->batch;
377
378 /*
379 * When there's less then two users of this mm there cannot be a
380 * concurrent page-table walk.
381 */
382 if (atomic_read(&tlb->mm->mm_users) < 2) {
383 __tlb_remove_table(table);
384 return;
385 }
386
387 if (*batch == NULL) {
388 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
389 if (*batch == NULL) {
390 tlb_remove_table_one(table);
391 return;
392 }
393 (*batch)->nr = 0;
394 }
395 (*batch)->tables[(*batch)->nr++] = table;
396 if ((*batch)->nr == MAX_TABLE_BATCH)
397 tlb_table_flush(tlb);
398}
399
400#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
401
402/**
403 * tlb_gather_mmu - initialize an mmu_gather structure for page-table tear-down
404 * @tlb: the mmu_gather structure to initialize
405 * @mm: the mm_struct of the target address space
406 * @start: start of the region that will be removed from the page-table
407 * @end: end of the region that will be removed from the page-table
408 *
409 * Called to initialize an (on-stack) mmu_gather structure for page-table
410 * tear-down from @mm. The @start and @end are set to 0 and -1
411 * respectively when @mm is without users and we're going to destroy
412 * the full address space (exit/execve).
413 */
414void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
415 unsigned long start, unsigned long end)
416{
417 arch_tlb_gather_mmu(tlb, mm, start, end);
418 inc_tlb_flush_pending(tlb->mm);
419}
420
421void tlb_finish_mmu(struct mmu_gather *tlb,
422 unsigned long start, unsigned long end)
423{
424 /*
425 * If there are parallel threads are doing PTE changes on same range
426 * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
427 * flush by batching, a thread has stable TLB entry can fail to flush
428 * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
429 * forcefully if we detect parallel PTE batching threads.
430 */
431 bool force = mm_tlb_flush_nested(tlb->mm);
432
433 arch_tlb_finish_mmu(tlb, start, end, force);
434 dec_tlb_flush_pending(tlb->mm);
435}
436
437/*
438 * Note: this doesn't free the actual pages themselves. That
439 * has been handled earlier when unmapping all the memory regions.
440 */
441static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
442 unsigned long addr)
443{
444 pgtable_t token = pmd_pgtable(*pmd);
445 pmd_clear(pmd);
446 pte_free_tlb(tlb, token, addr);
447 mm_dec_nr_ptes(tlb->mm);
448}
449
450static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
451 unsigned long addr, unsigned long end,
452 unsigned long floor, unsigned long ceiling)
453{
454 pmd_t *pmd;
455 unsigned long next;
456 unsigned long start;
457
458 start = addr;
459 pmd = pmd_offset(pud, addr);
460 do {
461 next = pmd_addr_end(addr, end);
462 if (pmd_none_or_clear_bad(pmd))
463 continue;
464 free_pte_range(tlb, pmd, addr);
465 } while (pmd++, addr = next, addr != end);
466
467 start &= PUD_MASK;
468 if (start < floor)
469 return;
470 if (ceiling) {
471 ceiling &= PUD_MASK;
472 if (!ceiling)
473 return;
474 }
475 if (end - 1 > ceiling - 1)
476 return;
477
478 pmd = pmd_offset(pud, start);
479 pud_clear(pud);
480 pmd_free_tlb(tlb, pmd, start);
481 mm_dec_nr_pmds(tlb->mm);
482}
483
484static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
485 unsigned long addr, unsigned long end,
486 unsigned long floor, unsigned long ceiling)
487{
488 pud_t *pud;
489 unsigned long next;
490 unsigned long start;
491
492 start = addr;
493 pud = pud_offset(p4d, addr);
494 do {
495 next = pud_addr_end(addr, end);
496 if (pud_none_or_clear_bad(pud))
497 continue;
498 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
499 } while (pud++, addr = next, addr != end);
500
501 start &= P4D_MASK;
502 if (start < floor)
503 return;
504 if (ceiling) {
505 ceiling &= P4D_MASK;
506 if (!ceiling)
507 return;
508 }
509 if (end - 1 > ceiling - 1)
510 return;
511
512 pud = pud_offset(p4d, start);
513 p4d_clear(p4d);
514 pud_free_tlb(tlb, pud, start);
515 mm_dec_nr_puds(tlb->mm);
516}
517
518static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
519 unsigned long addr, unsigned long end,
520 unsigned long floor, unsigned long ceiling)
521{
522 p4d_t *p4d;
523 unsigned long next;
524 unsigned long start;
525
526 start = addr;
527 p4d = p4d_offset(pgd, addr);
528 do {
529 next = p4d_addr_end(addr, end);
530 if (p4d_none_or_clear_bad(p4d))
531 continue;
532 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
533 } while (p4d++, addr = next, addr != end);
534
535 start &= PGDIR_MASK;
536 if (start < floor)
537 return;
538 if (ceiling) {
539 ceiling &= PGDIR_MASK;
540 if (!ceiling)
541 return;
542 }
543 if (end - 1 > ceiling - 1)
544 return;
545
546 p4d = p4d_offset(pgd, start);
547 pgd_clear(pgd);
548 p4d_free_tlb(tlb, p4d, start);
549}
550
551/*
552 * This function frees user-level page tables of a process.
553 */
554void free_pgd_range(struct mmu_gather *tlb,
555 unsigned long addr, unsigned long end,
556 unsigned long floor, unsigned long ceiling)
557{
558 pgd_t *pgd;
559 unsigned long next;
560
561 /*
562 * The next few lines have given us lots of grief...
563 *
564 * Why are we testing PMD* at this top level? Because often
565 * there will be no work to do at all, and we'd prefer not to
566 * go all the way down to the bottom just to discover that.
567 *
568 * Why all these "- 1"s? Because 0 represents both the bottom
569 * of the address space and the top of it (using -1 for the
570 * top wouldn't help much: the masks would do the wrong thing).
571 * The rule is that addr 0 and floor 0 refer to the bottom of
572 * the address space, but end 0 and ceiling 0 refer to the top
573 * Comparisons need to use "end - 1" and "ceiling - 1" (though
574 * that end 0 case should be mythical).
575 *
576 * Wherever addr is brought up or ceiling brought down, we must
577 * be careful to reject "the opposite 0" before it confuses the
578 * subsequent tests. But what about where end is brought down
579 * by PMD_SIZE below? no, end can't go down to 0 there.
580 *
581 * Whereas we round start (addr) and ceiling down, by different
582 * masks at different levels, in order to test whether a table
583 * now has no other vmas using it, so can be freed, we don't
584 * bother to round floor or end up - the tests don't need that.
585 */
586
587 addr &= PMD_MASK;
588 if (addr < floor) {
589 addr += PMD_SIZE;
590 if (!addr)
591 return;
592 }
593 if (ceiling) {
594 ceiling &= PMD_MASK;
595 if (!ceiling)
596 return;
597 }
598 if (end - 1 > ceiling - 1)
599 end -= PMD_SIZE;
600 if (addr > end - 1)
601 return;
602 /*
603 * We add page table cache pages with PAGE_SIZE,
604 * (see pte_free_tlb()), flush the tlb if we need
605 */
606 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
607 pgd = pgd_offset(tlb->mm, addr);
608 do {
609 next = pgd_addr_end(addr, end);
610 if (pgd_none_or_clear_bad(pgd))
611 continue;
612 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
613 } while (pgd++, addr = next, addr != end);
614}
615
616void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
617 unsigned long floor, unsigned long ceiling)
618{
619 while (vma) {
620 struct vm_area_struct *next = vma->vm_next;
621 unsigned long addr = vma->vm_start;
622
623 /*
624 * Hide vma from rmap and truncate_pagecache before freeing
625 * pgtables
626 */
627 unlink_anon_vmas(vma);
628 unlink_file_vma(vma);
629
630 if (is_vm_hugetlb_page(vma)) {
631 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
632 floor, next ? next->vm_start : ceiling);
633 } else {
634 /*
635 * Optimization: gather nearby vmas into one call down
636 */
637 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
638 && !is_vm_hugetlb_page(next)) {
639 vma = next;
640 next = vma->vm_next;
641 unlink_anon_vmas(vma);
642 unlink_file_vma(vma);
643 }
644 free_pgd_range(tlb, addr, vma->vm_end,
645 floor, next ? next->vm_start : ceiling);
646 }
647 vma = next;
648 }
649}
650
651int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
652{
653 spinlock_t *ptl;
654 pgtable_t new = pte_alloc_one(mm, address);
655 if (!new)
656 return -ENOMEM;
657
658 /*
659 * Ensure all pte setup (eg. pte page lock and page clearing) are
660 * visible before the pte is made visible to other CPUs by being
661 * put into page tables.
662 *
663 * The other side of the story is the pointer chasing in the page
664 * table walking code (when walking the page table without locking;
665 * ie. most of the time). Fortunately, these data accesses consist
666 * of a chain of data-dependent loads, meaning most CPUs (alpha
667 * being the notable exception) will already guarantee loads are
668 * seen in-order. See the alpha page table accessors for the
669 * smp_read_barrier_depends() barriers in page table walking code.
670 */
671 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
672
673 ptl = pmd_lock(mm, pmd);
674 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
675 mm_inc_nr_ptes(mm);
676 pmd_populate(mm, pmd, new);
677 new = NULL;
678 }
679 spin_unlock(ptl);
680 if (new)
681 pte_free(mm, new);
682 return 0;
683}
684
685int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
686{
687 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
688 if (!new)
689 return -ENOMEM;
690
691 smp_wmb(); /* See comment in __pte_alloc */
692
693 spin_lock(&init_mm.page_table_lock);
694 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
695 pmd_populate_kernel(&init_mm, pmd, new);
696 new = NULL;
697 }
698 spin_unlock(&init_mm.page_table_lock);
699 if (new)
700 pte_free_kernel(&init_mm, new);
701 return 0;
702}
703
704static inline void init_rss_vec(int *rss)
705{
706 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
707}
708
709static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
710{
711 int i;
712
713 if (current->mm == mm)
714 sync_mm_rss(mm);
715 for (i = 0; i < NR_MM_COUNTERS; i++)
716 if (rss[i])
717 add_mm_counter(mm, i, rss[i]);
718}
719
720/*
721 * This function is called to print an error when a bad pte
722 * is found. For example, we might have a PFN-mapped pte in
723 * a region that doesn't allow it.
724 *
725 * The calling function must still handle the error.
726 */
727static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
728 pte_t pte, struct page *page)
729{
730 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
731 p4d_t *p4d = p4d_offset(pgd, addr);
732 pud_t *pud = pud_offset(p4d, addr);
733 pmd_t *pmd = pmd_offset(pud, addr);
734 struct address_space *mapping;
735 pgoff_t index;
736 static unsigned long resume;
737 static unsigned long nr_shown;
738 static unsigned long nr_unshown;
739
740 /*
741 * Allow a burst of 60 reports, then keep quiet for that minute;
742 * or allow a steady drip of one report per second.
743 */
744 if (nr_shown == 60) {
745 if (time_before(jiffies, resume)) {
746 nr_unshown++;
747 return;
748 }
749 if (nr_unshown) {
750 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
751 nr_unshown);
752 nr_unshown = 0;
753 }
754 nr_shown = 0;
755 }
756 if (nr_shown++ == 0)
757 resume = jiffies + 60 * HZ;
758
759 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
760 index = linear_page_index(vma, addr);
761
762 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
763 current->comm,
764 (long long)pte_val(pte), (long long)pmd_val(*pmd));
765 if (page)
766 dump_page(page, "bad pte");
767 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
768 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
769 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
770 vma->vm_file,
771 vma->vm_ops ? vma->vm_ops->fault : NULL,
772 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
773 mapping ? mapping->a_ops->readpage : NULL);
774 dump_stack();
775 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
776}
777
778/*
779 * vm_normal_page -- This function gets the "struct page" associated with a pte.
780 *
781 * "Special" mappings do not wish to be associated with a "struct page" (either
782 * it doesn't exist, or it exists but they don't want to touch it). In this
783 * case, NULL is returned here. "Normal" mappings do have a struct page.
784 *
785 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
786 * pte bit, in which case this function is trivial. Secondly, an architecture
787 * may not have a spare pte bit, which requires a more complicated scheme,
788 * described below.
789 *
790 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
791 * special mapping (even if there are underlying and valid "struct pages").
792 * COWed pages of a VM_PFNMAP are always normal.
793 *
794 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
795 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
796 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
797 * mapping will always honor the rule
798 *
799 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
800 *
801 * And for normal mappings this is false.
802 *
803 * This restricts such mappings to be a linear translation from virtual address
804 * to pfn. To get around this restriction, we allow arbitrary mappings so long
805 * as the vma is not a COW mapping; in that case, we know that all ptes are
806 * special (because none can have been COWed).
807 *
808 *
809 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
810 *
811 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
812 * page" backing, however the difference is that _all_ pages with a struct
813 * page (that is, those where pfn_valid is true) are refcounted and considered
814 * normal pages by the VM. The disadvantage is that pages are refcounted
815 * (which can be slower and simply not an option for some PFNMAP users). The
816 * advantage is that we don't have to follow the strict linearity rule of
817 * PFNMAP mappings in order to support COWable mappings.
818 *
819 */
820#ifdef __HAVE_ARCH_PTE_SPECIAL
821# define HAVE_PTE_SPECIAL 1
822#else
823# define HAVE_PTE_SPECIAL 0
824#endif
825struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
826 pte_t pte, bool with_public_device)
827{
828 unsigned long pfn = pte_pfn(pte);
829
830 if (HAVE_PTE_SPECIAL) {
831 if (likely(!pte_special(pte)))
832 goto check_pfn;
833 if (vma->vm_ops && vma->vm_ops->find_special_page)
834 return vma->vm_ops->find_special_page(vma, addr);
835 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
836 return NULL;
837 if (is_zero_pfn(pfn))
838 return NULL;
839
840 /*
841 * Device public pages are special pages (they are ZONE_DEVICE
842 * pages but different from persistent memory). They behave
843 * allmost like normal pages. The difference is that they are
844 * not on the lru and thus should never be involve with any-
845 * thing that involve lru manipulation (mlock, numa balancing,
846 * ...).
847 *
848 * This is why we still want to return NULL for such page from
849 * vm_normal_page() so that we do not have to special case all
850 * call site of vm_normal_page().
851 */
852 if (likely(pfn <= highest_memmap_pfn)) {
853 struct page *page = pfn_to_page(pfn);
854
855 if (is_device_public_page(page)) {
856 if (with_public_device)
857 return page;
858 return NULL;
859 }
860 }
861 print_bad_pte(vma, addr, pte, NULL);
862 return NULL;
863 }
864
865 /* !HAVE_PTE_SPECIAL case follows: */
866
867 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
868 if (vma->vm_flags & VM_MIXEDMAP) {
869 if (!pfn_valid(pfn))
870 return NULL;
871 goto out;
872 } else {
873 unsigned long off;
874 off = (addr - vma->vm_start) >> PAGE_SHIFT;
875 if (pfn == vma->vm_pgoff + off)
876 return NULL;
877 if (!is_cow_mapping(vma->vm_flags))
878 return NULL;
879 }
880 }
881
882 if (is_zero_pfn(pfn))
883 return NULL;
884check_pfn:
885 if (unlikely(pfn > highest_memmap_pfn)) {
886 print_bad_pte(vma, addr, pte, NULL);
887 return NULL;
888 }
889
890 /*
891 * NOTE! We still have PageReserved() pages in the page tables.
892 * eg. VDSO mappings can cause them to exist.
893 */
894out:
895 return pfn_to_page(pfn);
896}
897
898#ifdef CONFIG_TRANSPARENT_HUGEPAGE
899struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
900 pmd_t pmd)
901{
902 unsigned long pfn = pmd_pfn(pmd);
903
904 /*
905 * There is no pmd_special() but there may be special pmds, e.g.
906 * in a direct-access (dax) mapping, so let's just replicate the
907 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
908 */
909 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
910 if (vma->vm_flags & VM_MIXEDMAP) {
911 if (!pfn_valid(pfn))
912 return NULL;
913 goto out;
914 } else {
915 unsigned long off;
916 off = (addr - vma->vm_start) >> PAGE_SHIFT;
917 if (pfn == vma->vm_pgoff + off)
918 return NULL;
919 if (!is_cow_mapping(vma->vm_flags))
920 return NULL;
921 }
922 }
923
924 if (is_zero_pfn(pfn))
925 return NULL;
926 if (unlikely(pfn > highest_memmap_pfn))
927 return NULL;
928
929 /*
930 * NOTE! We still have PageReserved() pages in the page tables.
931 * eg. VDSO mappings can cause them to exist.
932 */
933out:
934 return pfn_to_page(pfn);
935}
936#endif
937
938/*
939 * copy one vm_area from one task to the other. Assumes the page tables
940 * already present in the new task to be cleared in the whole range
941 * covered by this vma.
942 */
943
944static inline unsigned long
945copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
946 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
947 unsigned long addr, int *rss)
948{
949 unsigned long vm_flags = vma->vm_flags;
950 pte_t pte = *src_pte;
951 struct page *page;
952
953 /* pte contains position in swap or file, so copy. */
954 if (unlikely(!pte_present(pte))) {
955 swp_entry_t entry = pte_to_swp_entry(pte);
956
957 if (likely(!non_swap_entry(entry))) {
958 if (swap_duplicate(entry) < 0)
959 return entry.val;
960
961 /* make sure dst_mm is on swapoff's mmlist. */
962 if (unlikely(list_empty(&dst_mm->mmlist))) {
963 spin_lock(&mmlist_lock);
964 if (list_empty(&dst_mm->mmlist))
965 list_add(&dst_mm->mmlist,
966 &src_mm->mmlist);
967 spin_unlock(&mmlist_lock);
968 }
969 rss[MM_SWAPENTS]++;
970 } else if (is_migration_entry(entry)) {
971 page = migration_entry_to_page(entry);
972
973 rss[mm_counter(page)]++;
974
975 if (is_write_migration_entry(entry) &&
976 is_cow_mapping(vm_flags)) {
977 /*
978 * COW mappings require pages in both
979 * parent and child to be set to read.
980 */
981 make_migration_entry_read(&entry);
982 pte = swp_entry_to_pte(entry);
983 if (pte_swp_soft_dirty(*src_pte))
984 pte = pte_swp_mksoft_dirty(pte);
985 set_pte_at(src_mm, addr, src_pte, pte);
986 }
987 } else if (is_device_private_entry(entry)) {
988 page = device_private_entry_to_page(entry);
989
990 /*
991 * Update rss count even for unaddressable pages, as
992 * they should treated just like normal pages in this
993 * respect.
994 *
995 * We will likely want to have some new rss counters
996 * for unaddressable pages, at some point. But for now
997 * keep things as they are.
998 */
999 get_page(page);
1000 rss[mm_counter(page)]++;
1001 page_dup_rmap(page, false);
1002
1003 /*
1004 * We do not preserve soft-dirty information, because so
1005 * far, checkpoint/restore is the only feature that
1006 * requires that. And checkpoint/restore does not work
1007 * when a device driver is involved (you cannot easily
1008 * save and restore device driver state).
1009 */
1010 if (is_write_device_private_entry(entry) &&
1011 is_cow_mapping(vm_flags)) {
1012 make_device_private_entry_read(&entry);
1013 pte = swp_entry_to_pte(entry);
1014 set_pte_at(src_mm, addr, src_pte, pte);
1015 }
1016 }
1017 goto out_set_pte;
1018 }
1019
1020 /*
1021 * If it's a COW mapping, write protect it both
1022 * in the parent and the child
1023 */
1024 if (is_cow_mapping(vm_flags)) {
1025 ptep_set_wrprotect(src_mm, addr, src_pte);
1026 pte = pte_wrprotect(pte);
1027 }
1028
1029 /*
1030 * If it's a shared mapping, mark it clean in
1031 * the child
1032 */
1033 if (vm_flags & VM_SHARED)
1034 pte = pte_mkclean(pte);
1035 pte = pte_mkold(pte);
1036
1037 page = vm_normal_page(vma, addr, pte);
1038 if (page) {
1039 get_page(page);
1040 page_dup_rmap(page, false);
1041 rss[mm_counter(page)]++;
1042 } else if (pte_devmap(pte)) {
1043 page = pte_page(pte);
1044
1045 /*
1046 * Cache coherent device memory behave like regular page and
1047 * not like persistent memory page. For more informations see
1048 * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h
1049 */
1050 if (is_device_public_page(page)) {
1051 get_page(page);
1052 page_dup_rmap(page, false);
1053 rss[mm_counter(page)]++;
1054 }
1055 }
1056
1057out_set_pte:
1058 set_pte_at(dst_mm, addr, dst_pte, pte);
1059 return 0;
1060}
1061
1062static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1063 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
1064 unsigned long addr, unsigned long end)
1065{
1066 pte_t *orig_src_pte, *orig_dst_pte;
1067 pte_t *src_pte, *dst_pte;
1068 spinlock_t *src_ptl, *dst_ptl;
1069 int progress = 0;
1070 int rss[NR_MM_COUNTERS];
1071 swp_entry_t entry = (swp_entry_t){0};
1072
1073again:
1074 init_rss_vec(rss);
1075
1076 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1077 if (!dst_pte)
1078 return -ENOMEM;
1079 src_pte = pte_offset_map(src_pmd, addr);
1080 src_ptl = pte_lockptr(src_mm, src_pmd);
1081 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1082 orig_src_pte = src_pte;
1083 orig_dst_pte = dst_pte;
1084 arch_enter_lazy_mmu_mode();
1085
1086 do {
1087 /*
1088 * We are holding two locks at this point - either of them
1089 * could generate latencies in another task on another CPU.
1090 */
1091 if (progress >= 32) {
1092 progress = 0;
1093 if (need_resched() ||
1094 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1095 break;
1096 }
1097 if (pte_none(*src_pte)) {
1098 progress++;
1099 continue;
1100 }
1101 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1102 vma, addr, rss);
1103 if (entry.val)
1104 break;
1105 progress += 8;
1106 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1107
1108 arch_leave_lazy_mmu_mode();
1109 spin_unlock(src_ptl);
1110 pte_unmap(orig_src_pte);
1111 add_mm_rss_vec(dst_mm, rss);
1112 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1113 cond_resched();
1114
1115 if (entry.val) {
1116 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1117 return -ENOMEM;
1118 progress = 0;
1119 }
1120 if (addr != end)
1121 goto again;
1122 return 0;
1123}
1124
1125static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1126 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1127 unsigned long addr, unsigned long end)
1128{
1129 pmd_t *src_pmd, *dst_pmd;
1130 unsigned long next;
1131
1132 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1133 if (!dst_pmd)
1134 return -ENOMEM;
1135 src_pmd = pmd_offset(src_pud, addr);
1136 do {
1137 next = pmd_addr_end(addr, end);
1138 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1139 || pmd_devmap(*src_pmd)) {
1140 int err;
1141 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1142 err = copy_huge_pmd(dst_mm, src_mm,
1143 dst_pmd, src_pmd, addr, vma);
1144 if (err == -ENOMEM)
1145 return -ENOMEM;
1146 if (!err)
1147 continue;
1148 /* fall through */
1149 }
1150 if (pmd_none_or_clear_bad(src_pmd))
1151 continue;
1152 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1153 vma, addr, next))
1154 return -ENOMEM;
1155 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1156 return 0;
1157}
1158
1159static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1160 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1161 unsigned long addr, unsigned long end)
1162{
1163 pud_t *src_pud, *dst_pud;
1164 unsigned long next;
1165
1166 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1167 if (!dst_pud)
1168 return -ENOMEM;
1169 src_pud = pud_offset(src_p4d, addr);
1170 do {
1171 next = pud_addr_end(addr, end);
1172 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1173 int err;
1174
1175 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1176 err = copy_huge_pud(dst_mm, src_mm,
1177 dst_pud, src_pud, addr, vma);
1178 if (err == -ENOMEM)
1179 return -ENOMEM;
1180 if (!err)
1181 continue;
1182 /* fall through */
1183 }
1184 if (pud_none_or_clear_bad(src_pud))
1185 continue;
1186 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1187 vma, addr, next))
1188 return -ENOMEM;
1189 } while (dst_pud++, src_pud++, addr = next, addr != end);
1190 return 0;
1191}
1192
1193static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1194 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1195 unsigned long addr, unsigned long end)
1196{
1197 p4d_t *src_p4d, *dst_p4d;
1198 unsigned long next;
1199
1200 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1201 if (!dst_p4d)
1202 return -ENOMEM;
1203 src_p4d = p4d_offset(src_pgd, addr);
1204 do {
1205 next = p4d_addr_end(addr, end);
1206 if (p4d_none_or_clear_bad(src_p4d))
1207 continue;
1208 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1209 vma, addr, next))
1210 return -ENOMEM;
1211 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1212 return 0;
1213}
1214
1215int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1216 struct vm_area_struct *vma)
1217{
1218 pgd_t *src_pgd, *dst_pgd;
1219 unsigned long next;
1220 unsigned long addr = vma->vm_start;
1221 unsigned long end = vma->vm_end;
1222 unsigned long mmun_start; /* For mmu_notifiers */
1223 unsigned long mmun_end; /* For mmu_notifiers */
1224 bool is_cow;
1225 int ret;
1226
1227 /*
1228 * Don't copy ptes where a page fault will fill them correctly.
1229 * Fork becomes much lighter when there are big shared or private
1230 * readonly mappings. The tradeoff is that copy_page_range is more
1231 * efficient than faulting.
1232 */
1233 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1234 !vma->anon_vma)
1235 return 0;
1236
1237 if (is_vm_hugetlb_page(vma))
1238 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1239
1240 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1241 /*
1242 * We do not free on error cases below as remove_vma
1243 * gets called on error from higher level routine
1244 */
1245 ret = track_pfn_copy(vma);
1246 if (ret)
1247 return ret;
1248 }
1249
1250 /*
1251 * We need to invalidate the secondary MMU mappings only when
1252 * there could be a permission downgrade on the ptes of the
1253 * parent mm. And a permission downgrade will only happen if
1254 * is_cow_mapping() returns true.
1255 */
1256 is_cow = is_cow_mapping(vma->vm_flags);
1257 mmun_start = addr;
1258 mmun_end = end;
1259 if (is_cow)
1260 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1261 mmun_end);
1262
1263 ret = 0;
1264 dst_pgd = pgd_offset(dst_mm, addr);
1265 src_pgd = pgd_offset(src_mm, addr);
1266 do {
1267 next = pgd_addr_end(addr, end);
1268 if (pgd_none_or_clear_bad(src_pgd))
1269 continue;
1270 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1271 vma, addr, next))) {
1272 ret = -ENOMEM;
1273 break;
1274 }
1275 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1276
1277 if (is_cow)
1278 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1279 return ret;
1280}
1281
1282static unsigned long zap_pte_range(struct mmu_gather *tlb,
1283 struct vm_area_struct *vma, pmd_t *pmd,
1284 unsigned long addr, unsigned long end,
1285 struct zap_details *details)
1286{
1287 struct mm_struct *mm = tlb->mm;
1288 int force_flush = 0;
1289 int rss[NR_MM_COUNTERS];
1290 spinlock_t *ptl;
1291 pte_t *start_pte;
1292 pte_t *pte;
1293 swp_entry_t entry;
1294
1295 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1296again:
1297 init_rss_vec(rss);
1298 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1299 pte = start_pte;
1300 flush_tlb_batched_pending(mm);
1301 arch_enter_lazy_mmu_mode();
1302 do {
1303 pte_t ptent = *pte;
1304 if (pte_none(ptent))
1305 continue;
1306
1307 if (pte_present(ptent)) {
1308 struct page *page;
1309
1310 page = _vm_normal_page(vma, addr, ptent, true);
1311 if (unlikely(details) && page) {
1312 /*
1313 * unmap_shared_mapping_pages() wants to
1314 * invalidate cache without truncating:
1315 * unmap shared but keep private pages.
1316 */
1317 if (details->check_mapping &&
1318 details->check_mapping != page_rmapping(page))
1319 continue;
1320 }
1321 ptent = ptep_get_and_clear_full(mm, addr, pte,
1322 tlb->fullmm);
1323 tlb_remove_tlb_entry(tlb, pte, addr);
1324 if (unlikely(!page))
1325 continue;
1326
1327 if (!PageAnon(page)) {
1328 if (pte_dirty(ptent)) {
1329 force_flush = 1;
1330 set_page_dirty(page);
1331 }
1332 if (pte_young(ptent) &&
1333 likely(!(vma->vm_flags & VM_SEQ_READ)))
1334 mark_page_accessed(page);
1335 }
1336 rss[mm_counter(page)]--;
1337 page_remove_rmap(page, false);
1338 if (unlikely(page_mapcount(page) < 0))
1339 print_bad_pte(vma, addr, ptent, page);
1340 if (unlikely(__tlb_remove_page(tlb, page))) {
1341 force_flush = 1;
1342 addr += PAGE_SIZE;
1343 break;
1344 }
1345 continue;
1346 }
1347
1348 entry = pte_to_swp_entry(ptent);
1349 if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1350 struct page *page = device_private_entry_to_page(entry);
1351
1352 if (unlikely(details && details->check_mapping)) {
1353 /*
1354 * unmap_shared_mapping_pages() wants to
1355 * invalidate cache without truncating:
1356 * unmap shared but keep private pages.
1357 */
1358 if (details->check_mapping !=
1359 page_rmapping(page))
1360 continue;
1361 }
1362
1363 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1364 rss[mm_counter(page)]--;
1365 page_remove_rmap(page, false);
1366 put_page(page);
1367 continue;
1368 }
1369
1370 /* If details->check_mapping, we leave swap entries. */
1371 if (unlikely(details))
1372 continue;
1373
1374 entry = pte_to_swp_entry(ptent);
1375 if (!non_swap_entry(entry))
1376 rss[MM_SWAPENTS]--;
1377 else if (is_migration_entry(entry)) {
1378 struct page *page;
1379
1380 page = migration_entry_to_page(entry);
1381 rss[mm_counter(page)]--;
1382 }
1383 if (unlikely(!free_swap_and_cache(entry)))
1384 print_bad_pte(vma, addr, ptent, NULL);
1385 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1386 } while (pte++, addr += PAGE_SIZE, addr != end);
1387
1388 add_mm_rss_vec(mm, rss);
1389 arch_leave_lazy_mmu_mode();
1390
1391 /* Do the actual TLB flush before dropping ptl */
1392 if (force_flush)
1393 tlb_flush_mmu_tlbonly(tlb);
1394 pte_unmap_unlock(start_pte, ptl);
1395
1396 /*
1397 * If we forced a TLB flush (either due to running out of
1398 * batch buffers or because we needed to flush dirty TLB
1399 * entries before releasing the ptl), free the batched
1400 * memory too. Restart if we didn't do everything.
1401 */
1402 if (force_flush) {
1403 force_flush = 0;
1404 tlb_flush_mmu_free(tlb);
1405 if (addr != end)
1406 goto again;
1407 }
1408
1409 return addr;
1410}
1411
1412static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1413 struct vm_area_struct *vma, pud_t *pud,
1414 unsigned long addr, unsigned long end,
1415 struct zap_details *details)
1416{
1417 pmd_t *pmd;
1418 unsigned long next;
1419
1420 pmd = pmd_offset(pud, addr);
1421 do {
1422 next = pmd_addr_end(addr, end);
1423 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1424 if (next - addr != HPAGE_PMD_SIZE) {
1425 VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1426 !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1427 __split_huge_pmd(vma, pmd, addr, false, NULL);
1428 } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1429 goto next;
1430 /* fall through */
1431 }
1432 /*
1433 * Here there can be other concurrent MADV_DONTNEED or
1434 * trans huge page faults running, and if the pmd is
1435 * none or trans huge it can change under us. This is
1436 * because MADV_DONTNEED holds the mmap_sem in read
1437 * mode.
1438 */
1439 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1440 goto next;
1441 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1442next:
1443 cond_resched();
1444 } while (pmd++, addr = next, addr != end);
1445
1446 return addr;
1447}
1448
1449static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1450 struct vm_area_struct *vma, p4d_t *p4d,
1451 unsigned long addr, unsigned long end,
1452 struct zap_details *details)
1453{
1454 pud_t *pud;
1455 unsigned long next;
1456
1457 pud = pud_offset(p4d, addr);
1458 do {
1459 next = pud_addr_end(addr, end);
1460 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1461 if (next - addr != HPAGE_PUD_SIZE) {
1462 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1463 split_huge_pud(vma, pud, addr);
1464 } else if (zap_huge_pud(tlb, vma, pud, addr))
1465 goto next;
1466 /* fall through */
1467 }
1468 if (pud_none_or_clear_bad(pud))
1469 continue;
1470 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1471next:
1472 cond_resched();
1473 } while (pud++, addr = next, addr != end);
1474
1475 return addr;
1476}
1477
1478static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1479 struct vm_area_struct *vma, pgd_t *pgd,
1480 unsigned long addr, unsigned long end,
1481 struct zap_details *details)
1482{
1483 p4d_t *p4d;
1484 unsigned long next;
1485
1486 p4d = p4d_offset(pgd, addr);
1487 do {
1488 next = p4d_addr_end(addr, end);
1489 if (p4d_none_or_clear_bad(p4d))
1490 continue;
1491 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1492 } while (p4d++, addr = next, addr != end);
1493
1494 return addr;
1495}
1496
1497void unmap_page_range(struct mmu_gather *tlb,
1498 struct vm_area_struct *vma,
1499 unsigned long addr, unsigned long end,
1500 struct zap_details *details)
1501{
1502 pgd_t *pgd;
1503 unsigned long next;
1504
1505 BUG_ON(addr >= end);
1506 tlb_start_vma(tlb, vma);
1507 pgd = pgd_offset(vma->vm_mm, addr);
1508 do {
1509 next = pgd_addr_end(addr, end);
1510 if (pgd_none_or_clear_bad(pgd))
1511 continue;
1512 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1513 } while (pgd++, addr = next, addr != end);
1514 tlb_end_vma(tlb, vma);
1515}
1516
1517
1518static void unmap_single_vma(struct mmu_gather *tlb,
1519 struct vm_area_struct *vma, unsigned long start_addr,
1520 unsigned long end_addr,
1521 struct zap_details *details)
1522{
1523 unsigned long start = max(vma->vm_start, start_addr);
1524 unsigned long end;
1525
1526 if (start >= vma->vm_end)
1527 return;
1528 end = min(vma->vm_end, end_addr);
1529 if (end <= vma->vm_start)
1530 return;
1531
1532 if (vma->vm_file)
1533 uprobe_munmap(vma, start, end);
1534
1535 if (unlikely(vma->vm_flags & VM_PFNMAP))
1536 untrack_pfn(vma, 0, 0);
1537
1538 if (start != end) {
1539 if (unlikely(is_vm_hugetlb_page(vma))) {
1540 /*
1541 * It is undesirable to test vma->vm_file as it
1542 * should be non-null for valid hugetlb area.
1543 * However, vm_file will be NULL in the error
1544 * cleanup path of mmap_region. When
1545 * hugetlbfs ->mmap method fails,
1546 * mmap_region() nullifies vma->vm_file
1547 * before calling this function to clean up.
1548 * Since no pte has actually been setup, it is
1549 * safe to do nothing in this case.
1550 */
1551 if (vma->vm_file) {
1552 i_mmap_lock_write(vma->vm_file->f_mapping);
1553 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1554 i_mmap_unlock_write(vma->vm_file->f_mapping);
1555 }
1556 } else
1557 unmap_page_range(tlb, vma, start, end, details);
1558 }
1559}
1560
1561/**
1562 * unmap_vmas - unmap a range of memory covered by a list of vma's
1563 * @tlb: address of the caller's struct mmu_gather
1564 * @vma: the starting vma
1565 * @start_addr: virtual address at which to start unmapping
1566 * @end_addr: virtual address at which to end unmapping
1567 *
1568 * Unmap all pages in the vma list.
1569 *
1570 * Only addresses between `start' and `end' will be unmapped.
1571 *
1572 * The VMA list must be sorted in ascending virtual address order.
1573 *
1574 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1575 * range after unmap_vmas() returns. So the only responsibility here is to
1576 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1577 * drops the lock and schedules.
1578 */
1579void unmap_vmas(struct mmu_gather *tlb,
1580 struct vm_area_struct *vma, unsigned long start_addr,
1581 unsigned long end_addr)
1582{
1583 struct mm_struct *mm = vma->vm_mm;
1584
1585 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1586 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1587 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1588 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1589}
1590
1591/**
1592 * zap_page_range - remove user pages in a given range
1593 * @vma: vm_area_struct holding the applicable pages
1594 * @start: starting address of pages to zap
1595 * @size: number of bytes to zap
1596 *
1597 * Caller must protect the VMA list
1598 */
1599void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1600 unsigned long size)
1601{
1602 struct mm_struct *mm = vma->vm_mm;
1603 struct mmu_gather tlb;
1604 unsigned long end = start + size;
1605
1606 lru_add_drain();
1607 tlb_gather_mmu(&tlb, mm, start, end);
1608 update_hiwater_rss(mm);
1609 mmu_notifier_invalidate_range_start(mm, start, end);
1610 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
1611 unmap_single_vma(&tlb, vma, start, end, NULL);
1612
1613 /*
1614 * zap_page_range does not specify whether mmap_sem should be
1615 * held for read or write. That allows parallel zap_page_range
1616 * operations to unmap a PTE and defer a flush meaning that
1617 * this call observes pte_none and fails to flush the TLB.
1618 * Rather than adding a complex API, ensure that no stale
1619 * TLB entries exist when this call returns.
1620 */
1621 flush_tlb_range(vma, start, end);
1622 }
1623
1624 mmu_notifier_invalidate_range_end(mm, start, end);
1625 tlb_finish_mmu(&tlb, start, end);
1626}
1627
1628/**
1629 * zap_page_range_single - remove user pages in a given range
1630 * @vma: vm_area_struct holding the applicable pages
1631 * @address: starting address of pages to zap
1632 * @size: number of bytes to zap
1633 * @details: details of shared cache invalidation
1634 *
1635 * The range must fit into one VMA.
1636 */
1637static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1638 unsigned long size, struct zap_details *details)
1639{
1640 struct mm_struct *mm = vma->vm_mm;
1641 struct mmu_gather tlb;
1642 unsigned long end = address + size;
1643
1644 lru_add_drain();
1645 tlb_gather_mmu(&tlb, mm, address, end);
1646 update_hiwater_rss(mm);
1647 mmu_notifier_invalidate_range_start(mm, address, end);
1648 unmap_single_vma(&tlb, vma, address, end, details);
1649 mmu_notifier_invalidate_range_end(mm, address, end);
1650 tlb_finish_mmu(&tlb, address, end);
1651}
1652
1653/**
1654 * zap_vma_ptes - remove ptes mapping the vma
1655 * @vma: vm_area_struct holding ptes to be zapped
1656 * @address: starting address of pages to zap
1657 * @size: number of bytes to zap
1658 *
1659 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1660 *
1661 * The entire address range must be fully contained within the vma.
1662 *
1663 * Returns 0 if successful.
1664 */
1665int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1666 unsigned long size)
1667{
1668 if (address < vma->vm_start || address + size > vma->vm_end ||
1669 !(vma->vm_flags & VM_PFNMAP))
1670 return -1;
1671 zap_page_range_single(vma, address, size, NULL);
1672 return 0;
1673}
1674EXPORT_SYMBOL_GPL(zap_vma_ptes);
1675
1676pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1677 spinlock_t **ptl)
1678{
1679 pgd_t *pgd;
1680 p4d_t *p4d;
1681 pud_t *pud;
1682 pmd_t *pmd;
1683
1684 pgd = pgd_offset(mm, addr);
1685 p4d = p4d_alloc(mm, pgd, addr);
1686 if (!p4d)
1687 return NULL;
1688 pud = pud_alloc(mm, p4d, addr);
1689 if (!pud)
1690 return NULL;
1691 pmd = pmd_alloc(mm, pud, addr);
1692 if (!pmd)
1693 return NULL;
1694
1695 VM_BUG_ON(pmd_trans_huge(*pmd));
1696 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1697}
1698
1699/*
1700 * This is the old fallback for page remapping.
1701 *
1702 * For historical reasons, it only allows reserved pages. Only
1703 * old drivers should use this, and they needed to mark their
1704 * pages reserved for the old functions anyway.
1705 */
1706static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1707 struct page *page, pgprot_t prot)
1708{
1709 struct mm_struct *mm = vma->vm_mm;
1710 int retval;
1711 pte_t *pte;
1712 spinlock_t *ptl;
1713
1714 retval = -EINVAL;
1715 if (PageAnon(page))
1716 goto out;
1717 retval = -ENOMEM;
1718 flush_dcache_page(page);
1719 pte = get_locked_pte(mm, addr, &ptl);
1720 if (!pte)
1721 goto out;
1722 retval = -EBUSY;
1723 if (!pte_none(*pte))
1724 goto out_unlock;
1725
1726 /* Ok, finally just insert the thing.. */
1727 get_page(page);
1728 inc_mm_counter_fast(mm, mm_counter_file(page));
1729 page_add_file_rmap(page, false);
1730 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1731
1732 retval = 0;
1733 pte_unmap_unlock(pte, ptl);
1734 return retval;
1735out_unlock:
1736 pte_unmap_unlock(pte, ptl);
1737out:
1738 return retval;
1739}
1740
1741/**
1742 * vm_insert_page - insert single page into user vma
1743 * @vma: user vma to map to
1744 * @addr: target user address of this page
1745 * @page: source kernel page
1746 *
1747 * This allows drivers to insert individual pages they've allocated
1748 * into a user vma.
1749 *
1750 * The page has to be a nice clean _individual_ kernel allocation.
1751 * If you allocate a compound page, you need to have marked it as
1752 * such (__GFP_COMP), or manually just split the page up yourself
1753 * (see split_page()).
1754 *
1755 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1756 * took an arbitrary page protection parameter. This doesn't allow
1757 * that. Your vma protection will have to be set up correctly, which
1758 * means that if you want a shared writable mapping, you'd better
1759 * ask for a shared writable mapping!
1760 *
1761 * The page does not need to be reserved.
1762 *
1763 * Usually this function is called from f_op->mmap() handler
1764 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1765 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1766 * function from other places, for example from page-fault handler.
1767 */
1768int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1769 struct page *page)
1770{
1771 if (addr < vma->vm_start || addr >= vma->vm_end)
1772 return -EFAULT;
1773 if (!page_count(page))
1774 return -EINVAL;
1775 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1776 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1777 BUG_ON(vma->vm_flags & VM_PFNMAP);
1778 vma->vm_flags |= VM_MIXEDMAP;
1779 }
1780 return insert_page(vma, addr, page, vma->vm_page_prot);
1781}
1782EXPORT_SYMBOL(vm_insert_page);
1783
1784static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1785 pfn_t pfn, pgprot_t prot, bool mkwrite)
1786{
1787 struct mm_struct *mm = vma->vm_mm;
1788 int retval;
1789 pte_t *pte, entry;
1790 spinlock_t *ptl;
1791
1792 retval = -ENOMEM;
1793 pte = get_locked_pte(mm, addr, &ptl);
1794 if (!pte)
1795 goto out;
1796 retval = -EBUSY;
1797 if (!pte_none(*pte)) {
1798 if (mkwrite) {
1799 /*
1800 * For read faults on private mappings the PFN passed
1801 * in may not match the PFN we have mapped if the
1802 * mapped PFN is a writeable COW page. In the mkwrite
1803 * case we are creating a writable PTE for a shared
1804 * mapping and we expect the PFNs to match.
1805 */
1806 if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn)))
1807 goto out_unlock;
1808 entry = *pte;
1809 goto out_mkwrite;
1810 } else
1811 goto out_unlock;
1812 }
1813
1814 /* Ok, finally just insert the thing.. */
1815 if (pfn_t_devmap(pfn))
1816 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1817 else
1818 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1819
1820out_mkwrite:
1821 if (mkwrite) {
1822 entry = pte_mkyoung(entry);
1823 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1824 }
1825
1826 set_pte_at(mm, addr, pte, entry);
1827 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1828
1829 retval = 0;
1830out_unlock:
1831 pte_unmap_unlock(pte, ptl);
1832out:
1833 return retval;
1834}
1835
1836/**
1837 * vm_insert_pfn - insert single pfn into user vma
1838 * @vma: user vma to map to
1839 * @addr: target user address of this page
1840 * @pfn: source kernel pfn
1841 *
1842 * Similar to vm_insert_page, this allows drivers to insert individual pages
1843 * they've allocated into a user vma. Same comments apply.
1844 *
1845 * This function should only be called from a vm_ops->fault handler, and
1846 * in that case the handler should return NULL.
1847 *
1848 * vma cannot be a COW mapping.
1849 *
1850 * As this is called only for pages that do not currently exist, we
1851 * do not need to flush old virtual caches or the TLB.
1852 */
1853int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1854 unsigned long pfn)
1855{
1856 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1857}
1858EXPORT_SYMBOL(vm_insert_pfn);
1859
1860/**
1861 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1862 * @vma: user vma to map to
1863 * @addr: target user address of this page
1864 * @pfn: source kernel pfn
1865 * @pgprot: pgprot flags for the inserted page
1866 *
1867 * This is exactly like vm_insert_pfn, except that it allows drivers to
1868 * to override pgprot on a per-page basis.
1869 *
1870 * This only makes sense for IO mappings, and it makes no sense for
1871 * cow mappings. In general, using multiple vmas is preferable;
1872 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1873 * impractical.
1874 */
1875int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1876 unsigned long pfn, pgprot_t pgprot)
1877{
1878 int ret;
1879 /*
1880 * Technically, architectures with pte_special can avoid all these
1881 * restrictions (same for remap_pfn_range). However we would like
1882 * consistency in testing and feature parity among all, so we should
1883 * try to keep these invariants in place for everybody.
1884 */
1885 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1886 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1887 (VM_PFNMAP|VM_MIXEDMAP));
1888 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1889 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1890
1891 if (addr < vma->vm_start || addr >= vma->vm_end)
1892 return -EFAULT;
1893
1894 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1895
1896 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1897 false);
1898
1899 return ret;
1900}
1901EXPORT_SYMBOL(vm_insert_pfn_prot);
1902
1903static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
1904{
1905 /* these checks mirror the abort conditions in vm_normal_page */
1906 if (vma->vm_flags & VM_MIXEDMAP)
1907 return true;
1908 if (pfn_t_devmap(pfn))
1909 return true;
1910 if (pfn_t_special(pfn))
1911 return true;
1912 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
1913 return true;
1914 return false;
1915}
1916
1917static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1918 pfn_t pfn, bool mkwrite)
1919{
1920 pgprot_t pgprot = vma->vm_page_prot;
1921
1922 BUG_ON(!vm_mixed_ok(vma, pfn));
1923
1924 if (addr < vma->vm_start || addr >= vma->vm_end)
1925 return -EFAULT;
1926
1927 track_pfn_insert(vma, &pgprot, pfn);
1928
1929 /*
1930 * If we don't have pte special, then we have to use the pfn_valid()
1931 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1932 * refcount the page if pfn_valid is true (hence insert_page rather
1933 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1934 * without pte special, it would there be refcounted as a normal page.
1935 */
1936 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1937 struct page *page;
1938
1939 /*
1940 * At this point we are committed to insert_page()
1941 * regardless of whether the caller specified flags that
1942 * result in pfn_t_has_page() == false.
1943 */
1944 page = pfn_to_page(pfn_t_to_pfn(pfn));
1945 return insert_page(vma, addr, page, pgprot);
1946 }
1947 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1948}
1949
1950int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1951 pfn_t pfn)
1952{
1953 return __vm_insert_mixed(vma, addr, pfn, false);
1954
1955}
1956EXPORT_SYMBOL(vm_insert_mixed);
1957
1958int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
1959 pfn_t pfn)
1960{
1961 return __vm_insert_mixed(vma, addr, pfn, true);
1962}
1963EXPORT_SYMBOL(vm_insert_mixed_mkwrite);
1964
1965/*
1966 * maps a range of physical memory into the requested pages. the old
1967 * mappings are removed. any references to nonexistent pages results
1968 * in null mappings (currently treated as "copy-on-access")
1969 */
1970static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1971 unsigned long addr, unsigned long end,
1972 unsigned long pfn, pgprot_t prot)
1973{
1974 pte_t *pte;
1975 spinlock_t *ptl;
1976
1977 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1978 if (!pte)
1979 return -ENOMEM;
1980 arch_enter_lazy_mmu_mode();
1981 do {
1982 BUG_ON(!pte_none(*pte));
1983 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1984 pfn++;
1985 } while (pte++, addr += PAGE_SIZE, addr != end);
1986 arch_leave_lazy_mmu_mode();
1987 pte_unmap_unlock(pte - 1, ptl);
1988 return 0;
1989}
1990
1991static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1992 unsigned long addr, unsigned long end,
1993 unsigned long pfn, pgprot_t prot)
1994{
1995 pmd_t *pmd;
1996 unsigned long next;
1997
1998 pfn -= addr >> PAGE_SHIFT;
1999 pmd = pmd_alloc(mm, pud, addr);
2000 if (!pmd)
2001 return -ENOMEM;
2002 VM_BUG_ON(pmd_trans_huge(*pmd));
2003 do {
2004 next = pmd_addr_end(addr, end);
2005 if (remap_pte_range(mm, pmd, addr, next,
2006 pfn + (addr >> PAGE_SHIFT), prot))
2007 return -ENOMEM;
2008 } while (pmd++, addr = next, addr != end);
2009 return 0;
2010}
2011
2012static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2013 unsigned long addr, unsigned long end,
2014 unsigned long pfn, pgprot_t prot)
2015{
2016 pud_t *pud;
2017 unsigned long next;
2018
2019 pfn -= addr >> PAGE_SHIFT;
2020 pud = pud_alloc(mm, p4d, addr);
2021 if (!pud)
2022 return -ENOMEM;
2023 do {
2024 next = pud_addr_end(addr, end);
2025 if (remap_pmd_range(mm, pud, addr, next,
2026 pfn + (addr >> PAGE_SHIFT), prot))
2027 return -ENOMEM;
2028 } while (pud++, addr = next, addr != end);
2029 return 0;
2030}
2031
2032static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2033 unsigned long addr, unsigned long end,
2034 unsigned long pfn, pgprot_t prot)
2035{
2036 p4d_t *p4d;
2037 unsigned long next;
2038
2039 pfn -= addr >> PAGE_SHIFT;
2040 p4d = p4d_alloc(mm, pgd, addr);
2041 if (!p4d)
2042 return -ENOMEM;
2043 do {
2044 next = p4d_addr_end(addr, end);
2045 if (remap_pud_range(mm, p4d, addr, next,
2046 pfn + (addr >> PAGE_SHIFT), prot))
2047 return -ENOMEM;
2048 } while (p4d++, addr = next, addr != end);
2049 return 0;
2050}
2051
2052/**
2053 * remap_pfn_range - remap kernel memory to userspace
2054 * @vma: user vma to map to
2055 * @addr: target user address to start at
2056 * @pfn: physical address of kernel memory
2057 * @size: size of map area
2058 * @prot: page protection flags for this mapping
2059 *
2060 * Note: this is only safe if the mm semaphore is held when called.
2061 */
2062int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2063 unsigned long pfn, unsigned long size, pgprot_t prot)
2064{
2065 pgd_t *pgd;
2066 unsigned long next;
2067 unsigned long end = addr + PAGE_ALIGN(size);
2068 struct mm_struct *mm = vma->vm_mm;
2069 unsigned long remap_pfn = pfn;
2070 int err;
2071
2072 /*
2073 * Physically remapped pages are special. Tell the
2074 * rest of the world about it:
2075 * VM_IO tells people not to look at these pages
2076 * (accesses can have side effects).
2077 * VM_PFNMAP tells the core MM that the base pages are just
2078 * raw PFN mappings, and do not have a "struct page" associated
2079 * with them.
2080 * VM_DONTEXPAND
2081 * Disable vma merging and expanding with mremap().
2082 * VM_DONTDUMP
2083 * Omit vma from core dump, even when VM_IO turned off.
2084 *
2085 * There's a horrible special case to handle copy-on-write
2086 * behaviour that some programs depend on. We mark the "original"
2087 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2088 * See vm_normal_page() for details.
2089 */
2090 if (is_cow_mapping(vma->vm_flags)) {
2091 if (addr != vma->vm_start || end != vma->vm_end)
2092 return -EINVAL;
2093 vma->vm_pgoff = pfn;
2094 }
2095
2096 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
2097 if (err)
2098 return -EINVAL;
2099
2100 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2101
2102 BUG_ON(addr >= end);
2103 pfn -= addr >> PAGE_SHIFT;
2104 pgd = pgd_offset(mm, addr);
2105 flush_cache_range(vma, addr, end);
2106 do {
2107 next = pgd_addr_end(addr, end);
2108 err = remap_p4d_range(mm, pgd, addr, next,
2109 pfn + (addr >> PAGE_SHIFT), prot);
2110 if (err)
2111 break;
2112 } while (pgd++, addr = next, addr != end);
2113
2114 if (err)
2115 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
2116
2117 return err;
2118}
2119EXPORT_SYMBOL(remap_pfn_range);
2120
2121/**
2122 * vm_iomap_memory - remap memory to userspace
2123 * @vma: user vma to map to
2124 * @start: start of area
2125 * @len: size of area
2126 *
2127 * This is a simplified io_remap_pfn_range() for common driver use. The
2128 * driver just needs to give us the physical memory range to be mapped,
2129 * we'll figure out the rest from the vma information.
2130 *
2131 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2132 * whatever write-combining details or similar.
2133 */
2134int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2135{
2136 unsigned long vm_len, pfn, pages;
2137
2138 /* Check that the physical memory area passed in looks valid */
2139 if (start + len < start)
2140 return -EINVAL;
2141 /*
2142 * You *really* shouldn't map things that aren't page-aligned,
2143 * but we've historically allowed it because IO memory might
2144 * just have smaller alignment.
2145 */
2146 len += start & ~PAGE_MASK;
2147 pfn = start >> PAGE_SHIFT;
2148 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2149 if (pfn + pages < pfn)
2150 return -EINVAL;
2151
2152 /* We start the mapping 'vm_pgoff' pages into the area */
2153 if (vma->vm_pgoff > pages)
2154 return -EINVAL;
2155 pfn += vma->vm_pgoff;
2156 pages -= vma->vm_pgoff;
2157
2158 /* Can we fit all of the mapping? */
2159 vm_len = vma->vm_end - vma->vm_start;
2160 if (vm_len >> PAGE_SHIFT > pages)
2161 return -EINVAL;
2162
2163 /* Ok, let it rip */
2164 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2165}
2166EXPORT_SYMBOL(vm_iomap_memory);
2167
2168static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2169 unsigned long addr, unsigned long end,
2170 pte_fn_t fn, void *data)
2171{
2172 pte_t *pte;
2173 int err;
2174 pgtable_t token;
2175 spinlock_t *uninitialized_var(ptl);
2176
2177 pte = (mm == &init_mm) ?
2178 pte_alloc_kernel(pmd, addr) :
2179 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2180 if (!pte)
2181 return -ENOMEM;
2182
2183 BUG_ON(pmd_huge(*pmd));
2184
2185 arch_enter_lazy_mmu_mode();
2186
2187 token = pmd_pgtable(*pmd);
2188
2189 do {
2190 err = fn(pte++, token, addr, data);
2191 if (err)
2192 break;
2193 } while (addr += PAGE_SIZE, addr != end);
2194
2195 arch_leave_lazy_mmu_mode();
2196
2197 if (mm != &init_mm)
2198 pte_unmap_unlock(pte-1, ptl);
2199 return err;
2200}
2201
2202static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2203 unsigned long addr, unsigned long end,
2204 pte_fn_t fn, void *data)
2205{
2206 pmd_t *pmd;
2207 unsigned long next;
2208 int err;
2209
2210 BUG_ON(pud_huge(*pud));
2211
2212 pmd = pmd_alloc(mm, pud, addr);
2213 if (!pmd)
2214 return -ENOMEM;
2215 do {
2216 next = pmd_addr_end(addr, end);
2217 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2218 if (err)
2219 break;
2220 } while (pmd++, addr = next, addr != end);
2221 return err;
2222}
2223
2224static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2225 unsigned long addr, unsigned long end,
2226 pte_fn_t fn, void *data)
2227{
2228 pud_t *pud;
2229 unsigned long next;
2230 int err;
2231
2232 pud = pud_alloc(mm, p4d, addr);
2233 if (!pud)
2234 return -ENOMEM;
2235 do {
2236 next = pud_addr_end(addr, end);
2237 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2238 if (err)
2239 break;
2240 } while (pud++, addr = next, addr != end);
2241 return err;
2242}
2243
2244static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2245 unsigned long addr, unsigned long end,
2246 pte_fn_t fn, void *data)
2247{
2248 p4d_t *p4d;
2249 unsigned long next;
2250 int err;
2251
2252 p4d = p4d_alloc(mm, pgd, addr);
2253 if (!p4d)
2254 return -ENOMEM;
2255 do {
2256 next = p4d_addr_end(addr, end);
2257 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2258 if (err)
2259 break;
2260 } while (p4d++, addr = next, addr != end);
2261 return err;
2262}
2263
2264/*
2265 * Scan a region of virtual memory, filling in page tables as necessary
2266 * and calling a provided function on each leaf page table.
2267 */
2268int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2269 unsigned long size, pte_fn_t fn, void *data)
2270{
2271 pgd_t *pgd;
2272 unsigned long next;
2273 unsigned long end = addr + size;
2274 int err;
2275
2276 if (WARN_ON(addr >= end))
2277 return -EINVAL;
2278
2279 pgd = pgd_offset(mm, addr);
2280 do {
2281 next = pgd_addr_end(addr, end);
2282 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2283 if (err)
2284 break;
2285 } while (pgd++, addr = next, addr != end);
2286
2287 return err;
2288}
2289EXPORT_SYMBOL_GPL(apply_to_page_range);
2290
2291/*
2292 * handle_pte_fault chooses page fault handler according to an entry which was
2293 * read non-atomically. Before making any commitment, on those architectures
2294 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2295 * parts, do_swap_page must check under lock before unmapping the pte and
2296 * proceeding (but do_wp_page is only called after already making such a check;
2297 * and do_anonymous_page can safely check later on).
2298 */
2299static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2300 pte_t *page_table, pte_t orig_pte)
2301{
2302 int same = 1;
2303#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2304 if (sizeof(pte_t) > sizeof(unsigned long)) {
2305 spinlock_t *ptl = pte_lockptr(mm, pmd);
2306 spin_lock(ptl);
2307 same = pte_same(*page_table, orig_pte);
2308 spin_unlock(ptl);
2309 }
2310#endif
2311 pte_unmap(page_table);
2312 return same;
2313}
2314
2315static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2316{
2317 debug_dma_assert_idle(src);
2318
2319 /*
2320 * If the source page was a PFN mapping, we don't have
2321 * a "struct page" for it. We do a best-effort copy by
2322 * just copying from the original user address. If that
2323 * fails, we just zero-fill it. Live with it.
2324 */
2325 if (unlikely(!src)) {
2326 void *kaddr = kmap_atomic(dst);
2327 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2328
2329 /*
2330 * This really shouldn't fail, because the page is there
2331 * in the page tables. But it might just be unreadable,
2332 * in which case we just give up and fill the result with
2333 * zeroes.
2334 */
2335 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2336 clear_page(kaddr);
2337 kunmap_atomic(kaddr);
2338 flush_dcache_page(dst);
2339 } else
2340 copy_user_highpage(dst, src, va, vma);
2341}
2342
2343static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2344{
2345 struct file *vm_file = vma->vm_file;
2346
2347 if (vm_file)
2348 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2349
2350 /*
2351 * Special mappings (e.g. VDSO) do not have any file so fake
2352 * a default GFP_KERNEL for them.
2353 */
2354 return GFP_KERNEL;
2355}
2356
2357/*
2358 * Notify the address space that the page is about to become writable so that
2359 * it can prohibit this or wait for the page to get into an appropriate state.
2360 *
2361 * We do this without the lock held, so that it can sleep if it needs to.
2362 */
2363static int do_page_mkwrite(struct vm_fault *vmf)
2364{
2365 int ret;
2366 struct page *page = vmf->page;
2367 unsigned int old_flags = vmf->flags;
2368
2369 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2370
2371 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2372 /* Restore original flags so that caller is not surprised */
2373 vmf->flags = old_flags;
2374 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2375 return ret;
2376 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2377 lock_page(page);
2378 if (!page->mapping) {
2379 unlock_page(page);
2380 return 0; /* retry */
2381 }
2382 ret |= VM_FAULT_LOCKED;
2383 } else
2384 VM_BUG_ON_PAGE(!PageLocked(page), page);
2385 return ret;
2386}
2387
2388/*
2389 * Handle dirtying of a page in shared file mapping on a write fault.
2390 *
2391 * The function expects the page to be locked and unlocks it.
2392 */
2393static void fault_dirty_shared_page(struct vm_area_struct *vma,
2394 struct page *page)
2395{
2396 struct address_space *mapping;
2397 bool dirtied;
2398 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2399
2400 dirtied = set_page_dirty(page);
2401 VM_BUG_ON_PAGE(PageAnon(page), page);
2402 /*
2403 * Take a local copy of the address_space - page.mapping may be zeroed
2404 * by truncate after unlock_page(). The address_space itself remains
2405 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2406 * release semantics to prevent the compiler from undoing this copying.
2407 */
2408 mapping = page_rmapping(page);
2409 unlock_page(page);
2410
2411 if ((dirtied || page_mkwrite) && mapping) {
2412 /*
2413 * Some device drivers do not set page.mapping
2414 * but still dirty their pages
2415 */
2416 balance_dirty_pages_ratelimited(mapping);
2417 }
2418
2419 if (!page_mkwrite)
2420 file_update_time(vma->vm_file);
2421}
2422
2423/*
2424 * Handle write page faults for pages that can be reused in the current vma
2425 *
2426 * This can happen either due to the mapping being with the VM_SHARED flag,
2427 * or due to us being the last reference standing to the page. In either
2428 * case, all we need to do here is to mark the page as writable and update
2429 * any related book-keeping.
2430 */
2431static inline void wp_page_reuse(struct vm_fault *vmf)
2432 __releases(vmf->ptl)
2433{
2434 struct vm_area_struct *vma = vmf->vma;
2435 struct page *page = vmf->page;
2436 pte_t entry;
2437 /*
2438 * Clear the pages cpupid information as the existing
2439 * information potentially belongs to a now completely
2440 * unrelated process.
2441 */
2442 if (page)
2443 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2444
2445 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2446 entry = pte_mkyoung(vmf->orig_pte);
2447 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2448 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2449 update_mmu_cache(vma, vmf->address, vmf->pte);
2450 pte_unmap_unlock(vmf->pte, vmf->ptl);
2451}
2452
2453/*
2454 * Handle the case of a page which we actually need to copy to a new page.
2455 *
2456 * Called with mmap_sem locked and the old page referenced, but
2457 * without the ptl held.
2458 *
2459 * High level logic flow:
2460 *
2461 * - Allocate a page, copy the content of the old page to the new one.
2462 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2463 * - Take the PTL. If the pte changed, bail out and release the allocated page
2464 * - If the pte is still the way we remember it, update the page table and all
2465 * relevant references. This includes dropping the reference the page-table
2466 * held to the old page, as well as updating the rmap.
2467 * - In any case, unlock the PTL and drop the reference we took to the old page.
2468 */
2469static int wp_page_copy(struct vm_fault *vmf)
2470{
2471 struct vm_area_struct *vma = vmf->vma;
2472 struct mm_struct *mm = vma->vm_mm;
2473 struct page *old_page = vmf->page;
2474 struct page *new_page = NULL;
2475 pte_t entry;
2476 int page_copied = 0;
2477 const unsigned long mmun_start = vmf->address & PAGE_MASK;
2478 const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2479 struct mem_cgroup *memcg;
2480
2481 if (unlikely(anon_vma_prepare(vma)))
2482 goto oom;
2483
2484 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2485 new_page = alloc_zeroed_user_highpage_movable(vma,
2486 vmf->address);
2487 if (!new_page)
2488 goto oom;
2489 } else {
2490 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2491 vmf->address);
2492 if (!new_page)
2493 goto oom;
2494 cow_user_page(new_page, old_page, vmf->address, vma);
2495 }
2496
2497 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2498 goto oom_free_new;
2499
2500 __SetPageUptodate(new_page);
2501
2502 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2503
2504 /*
2505 * Re-check the pte - we dropped the lock
2506 */
2507 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2508 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2509 if (old_page) {
2510 if (!PageAnon(old_page)) {
2511 dec_mm_counter_fast(mm,
2512 mm_counter_file(old_page));
2513 inc_mm_counter_fast(mm, MM_ANONPAGES);
2514 }
2515 } else {
2516 inc_mm_counter_fast(mm, MM_ANONPAGES);
2517 }
2518 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2519 entry = mk_pte(new_page, vma->vm_page_prot);
2520 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2521 /*
2522 * Clear the pte entry and flush it first, before updating the
2523 * pte with the new entry. This will avoid a race condition
2524 * seen in the presence of one thread doing SMC and another
2525 * thread doing COW.
2526 */
2527 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2528 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2529 mem_cgroup_commit_charge(new_page, memcg, false, false);
2530 lru_cache_add_active_or_unevictable(new_page, vma);
2531 /*
2532 * We call the notify macro here because, when using secondary
2533 * mmu page tables (such as kvm shadow page tables), we want the
2534 * new page to be mapped directly into the secondary page table.
2535 */
2536 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2537 update_mmu_cache(vma, vmf->address, vmf->pte);
2538 if (old_page) {
2539 /*
2540 * Only after switching the pte to the new page may
2541 * we remove the mapcount here. Otherwise another
2542 * process may come and find the rmap count decremented
2543 * before the pte is switched to the new page, and
2544 * "reuse" the old page writing into it while our pte
2545 * here still points into it and can be read by other
2546 * threads.
2547 *
2548 * The critical issue is to order this
2549 * page_remove_rmap with the ptp_clear_flush above.
2550 * Those stores are ordered by (if nothing else,)
2551 * the barrier present in the atomic_add_negative
2552 * in page_remove_rmap.
2553 *
2554 * Then the TLB flush in ptep_clear_flush ensures that
2555 * no process can access the old page before the
2556 * decremented mapcount is visible. And the old page
2557 * cannot be reused until after the decremented
2558 * mapcount is visible. So transitively, TLBs to
2559 * old page will be flushed before it can be reused.
2560 */
2561 page_remove_rmap(old_page, false);
2562 }
2563
2564 /* Free the old page.. */
2565 new_page = old_page;
2566 page_copied = 1;
2567 } else {
2568 mem_cgroup_cancel_charge(new_page, memcg, false);
2569 }
2570
2571 if (new_page)
2572 put_page(new_page);
2573
2574 pte_unmap_unlock(vmf->pte, vmf->ptl);
2575 /*
2576 * No need to double call mmu_notifier->invalidate_range() callback as
2577 * the above ptep_clear_flush_notify() did already call it.
2578 */
2579 mmu_notifier_invalidate_range_only_end(mm, mmun_start, mmun_end);
2580 if (old_page) {
2581 /*
2582 * Don't let another task, with possibly unlocked vma,
2583 * keep the mlocked page.
2584 */
2585 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2586 lock_page(old_page); /* LRU manipulation */
2587 if (PageMlocked(old_page))
2588 munlock_vma_page(old_page);
2589 unlock_page(old_page);
2590 }
2591 put_page(old_page);
2592 }
2593 return page_copied ? VM_FAULT_WRITE : 0;
2594oom_free_new:
2595 put_page(new_page);
2596oom:
2597 if (old_page)
2598 put_page(old_page);
2599 return VM_FAULT_OOM;
2600}
2601
2602/**
2603 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2604 * writeable once the page is prepared
2605 *
2606 * @vmf: structure describing the fault
2607 *
2608 * This function handles all that is needed to finish a write page fault in a
2609 * shared mapping due to PTE being read-only once the mapped page is prepared.
2610 * It handles locking of PTE and modifying it. The function returns
2611 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2612 * lock.
2613 *
2614 * The function expects the page to be locked or other protection against
2615 * concurrent faults / writeback (such as DAX radix tree locks).
2616 */
2617int finish_mkwrite_fault(struct vm_fault *vmf)
2618{
2619 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2620 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2621 &vmf->ptl);
2622 /*
2623 * We might have raced with another page fault while we released the
2624 * pte_offset_map_lock.
2625 */
2626 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2627 pte_unmap_unlock(vmf->pte, vmf->ptl);
2628 return VM_FAULT_NOPAGE;
2629 }
2630 wp_page_reuse(vmf);
2631 return 0;
2632}
2633
2634/*
2635 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2636 * mapping
2637 */
2638static int wp_pfn_shared(struct vm_fault *vmf)
2639{
2640 struct vm_area_struct *vma = vmf->vma;
2641
2642 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2643 int ret;
2644
2645 pte_unmap_unlock(vmf->pte, vmf->ptl);
2646 vmf->flags |= FAULT_FLAG_MKWRITE;
2647 ret = vma->vm_ops->pfn_mkwrite(vmf);
2648 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2649 return ret;
2650 return finish_mkwrite_fault(vmf);
2651 }
2652 wp_page_reuse(vmf);
2653 return VM_FAULT_WRITE;
2654}
2655
2656static int wp_page_shared(struct vm_fault *vmf)
2657 __releases(vmf->ptl)
2658{
2659 struct vm_area_struct *vma = vmf->vma;
2660
2661 get_page(vmf->page);
2662
2663 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2664 int tmp;
2665
2666 pte_unmap_unlock(vmf->pte, vmf->ptl);
2667 tmp = do_page_mkwrite(vmf);
2668 if (unlikely(!tmp || (tmp &
2669 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2670 put_page(vmf->page);
2671 return tmp;
2672 }
2673 tmp = finish_mkwrite_fault(vmf);
2674 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2675 unlock_page(vmf->page);
2676 put_page(vmf->page);
2677 return tmp;
2678 }
2679 } else {
2680 wp_page_reuse(vmf);
2681 lock_page(vmf->page);
2682 }
2683 fault_dirty_shared_page(vma, vmf->page);
2684 put_page(vmf->page);
2685
2686 return VM_FAULT_WRITE;
2687}
2688
2689/*
2690 * This routine handles present pages, when users try to write
2691 * to a shared page. It is done by copying the page to a new address
2692 * and decrementing the shared-page counter for the old page.
2693 *
2694 * Note that this routine assumes that the protection checks have been
2695 * done by the caller (the low-level page fault routine in most cases).
2696 * Thus we can safely just mark it writable once we've done any necessary
2697 * COW.
2698 *
2699 * We also mark the page dirty at this point even though the page will
2700 * change only once the write actually happens. This avoids a few races,
2701 * and potentially makes it more efficient.
2702 *
2703 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2704 * but allow concurrent faults), with pte both mapped and locked.
2705 * We return with mmap_sem still held, but pte unmapped and unlocked.
2706 */
2707static int do_wp_page(struct vm_fault *vmf)
2708 __releases(vmf->ptl)
2709{
2710 struct vm_area_struct *vma = vmf->vma;
2711
2712 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2713 if (!vmf->page) {
2714 /*
2715 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2716 * VM_PFNMAP VMA.
2717 *
2718 * We should not cow pages in a shared writeable mapping.
2719 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2720 */
2721 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2722 (VM_WRITE|VM_SHARED))
2723 return wp_pfn_shared(vmf);
2724
2725 pte_unmap_unlock(vmf->pte, vmf->ptl);
2726 return wp_page_copy(vmf);
2727 }
2728
2729 /*
2730 * Take out anonymous pages first, anonymous shared vmas are
2731 * not dirty accountable.
2732 */
2733 if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2734 int total_map_swapcount;
2735 if (!trylock_page(vmf->page)) {
2736 get_page(vmf->page);
2737 pte_unmap_unlock(vmf->pte, vmf->ptl);
2738 lock_page(vmf->page);
2739 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2740 vmf->address, &vmf->ptl);
2741 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2742 unlock_page(vmf->page);
2743 pte_unmap_unlock(vmf->pte, vmf->ptl);
2744 put_page(vmf->page);
2745 return 0;
2746 }
2747 put_page(vmf->page);
2748 }
2749 if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2750 if (total_map_swapcount == 1) {
2751 /*
2752 * The page is all ours. Move it to
2753 * our anon_vma so the rmap code will
2754 * not search our parent or siblings.
2755 * Protected against the rmap code by
2756 * the page lock.
2757 */
2758 page_move_anon_rmap(vmf->page, vma);
2759 }
2760 unlock_page(vmf->page);
2761 wp_page_reuse(vmf);
2762 return VM_FAULT_WRITE;
2763 }
2764 unlock_page(vmf->page);
2765 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2766 (VM_WRITE|VM_SHARED))) {
2767 return wp_page_shared(vmf);
2768 }
2769
2770 /*
2771 * Ok, we need to copy. Oh, well..
2772 */
2773 get_page(vmf->page);
2774
2775 pte_unmap_unlock(vmf->pte, vmf->ptl);
2776 return wp_page_copy(vmf);
2777}
2778
2779static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2780 unsigned long start_addr, unsigned long end_addr,
2781 struct zap_details *details)
2782{
2783 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2784}
2785
2786static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2787 struct zap_details *details)
2788{
2789 struct vm_area_struct *vma;
2790 pgoff_t vba, vea, zba, zea;
2791
2792 vma_interval_tree_foreach(vma, root,
2793 details->first_index, details->last_index) {
2794
2795 vba = vma->vm_pgoff;
2796 vea = vba + vma_pages(vma) - 1;
2797 zba = details->first_index;
2798 if (zba < vba)
2799 zba = vba;
2800 zea = details->last_index;
2801 if (zea > vea)
2802 zea = vea;
2803
2804 unmap_mapping_range_vma(vma,
2805 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2806 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2807 details);
2808 }
2809}
2810
2811/**
2812 * unmap_mapping_pages() - Unmap pages from processes.
2813 * @mapping: The address space containing pages to be unmapped.
2814 * @start: Index of first page to be unmapped.
2815 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
2816 * @even_cows: Whether to unmap even private COWed pages.
2817 *
2818 * Unmap the pages in this address space from any userspace process which
2819 * has them mmaped. Generally, you want to remove COWed pages as well when
2820 * a file is being truncated, but not when invalidating pages from the page
2821 * cache.
2822 */
2823void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
2824 pgoff_t nr, bool even_cows)
2825{
2826 struct zap_details details = { };
2827
2828 details.check_mapping = even_cows ? NULL : mapping;
2829 details.first_index = start;
2830 details.last_index = start + nr - 1;
2831 if (details.last_index < details.first_index)
2832 details.last_index = ULONG_MAX;
2833
2834 i_mmap_lock_write(mapping);
2835 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2836 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2837 i_mmap_unlock_write(mapping);
2838}
2839
2840/**
2841 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2842 * address_space corresponding to the specified byte range in the underlying
2843 * file.
2844 *
2845 * @mapping: the address space containing mmaps to be unmapped.
2846 * @holebegin: byte in first page to unmap, relative to the start of
2847 * the underlying file. This will be rounded down to a PAGE_SIZE
2848 * boundary. Note that this is different from truncate_pagecache(), which
2849 * must keep the partial page. In contrast, we must get rid of
2850 * partial pages.
2851 * @holelen: size of prospective hole in bytes. This will be rounded
2852 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2853 * end of the file.
2854 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2855 * but 0 when invalidating pagecache, don't throw away private data.
2856 */
2857void unmap_mapping_range(struct address_space *mapping,
2858 loff_t const holebegin, loff_t const holelen, int even_cows)
2859{
2860 pgoff_t hba = holebegin >> PAGE_SHIFT;
2861 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2862
2863 /* Check for overflow. */
2864 if (sizeof(holelen) > sizeof(hlen)) {
2865 long long holeend =
2866 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2867 if (holeend & ~(long long)ULONG_MAX)
2868 hlen = ULONG_MAX - hba + 1;
2869 }
2870
2871 unmap_mapping_pages(mapping, hba, hlen, even_cows);
2872}
2873EXPORT_SYMBOL(unmap_mapping_range);
2874
2875/*
2876 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2877 * but allow concurrent faults), and pte mapped but not yet locked.
2878 * We return with pte unmapped and unlocked.
2879 *
2880 * We return with the mmap_sem locked or unlocked in the same cases
2881 * as does filemap_fault().
2882 */
2883int do_swap_page(struct vm_fault *vmf)
2884{
2885 struct vm_area_struct *vma = vmf->vma;
2886 struct page *page = NULL, *swapcache;
2887 struct mem_cgroup *memcg;
2888 swp_entry_t entry;
2889 pte_t pte;
2890 int locked;
2891 int exclusive = 0;
2892 int ret = 0;
2893
2894 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2895 goto out;
2896
2897 entry = pte_to_swp_entry(vmf->orig_pte);
2898 if (unlikely(non_swap_entry(entry))) {
2899 if (is_migration_entry(entry)) {
2900 migration_entry_wait(vma->vm_mm, vmf->pmd,
2901 vmf->address);
2902 } else if (is_device_private_entry(entry)) {
2903 /*
2904 * For un-addressable device memory we call the pgmap
2905 * fault handler callback. The callback must migrate
2906 * the page back to some CPU accessible page.
2907 */
2908 ret = device_private_entry_fault(vma, vmf->address, entry,
2909 vmf->flags, vmf->pmd);
2910 } else if (is_hwpoison_entry(entry)) {
2911 ret = VM_FAULT_HWPOISON;
2912 } else {
2913 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2914 ret = VM_FAULT_SIGBUS;
2915 }
2916 goto out;
2917 }
2918
2919
2920 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2921 page = lookup_swap_cache(entry, vma, vmf->address);
2922 swapcache = page;
2923
2924 if (!page) {
2925 struct swap_info_struct *si = swp_swap_info(entry);
2926
2927 if (si->flags & SWP_SYNCHRONOUS_IO &&
2928 __swap_count(si, entry) == 1) {
2929 /* skip swapcache */
2930 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2931 vmf->address);
2932 if (page) {
2933 __SetPageLocked(page);
2934 __SetPageSwapBacked(page);
2935 set_page_private(page, entry.val);
2936 lru_cache_add_anon(page);
2937 swap_readpage(page, true);
2938 }
2939 } else {
2940 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
2941 vmf);
2942 swapcache = page;
2943 }
2944
2945 if (!page) {
2946 /*
2947 * Back out if somebody else faulted in this pte
2948 * while we released the pte lock.
2949 */
2950 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2951 vmf->address, &vmf->ptl);
2952 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2953 ret = VM_FAULT_OOM;
2954 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2955 goto unlock;
2956 }
2957
2958 /* Had to read the page from swap area: Major fault */
2959 ret = VM_FAULT_MAJOR;
2960 count_vm_event(PGMAJFAULT);
2961 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2962 } else if (PageHWPoison(page)) {
2963 /*
2964 * hwpoisoned dirty swapcache pages are kept for killing
2965 * owner processes (which may be unknown at hwpoison time)
2966 */
2967 ret = VM_FAULT_HWPOISON;
2968 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2969 goto out_release;
2970 }
2971
2972 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2973
2974 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2975 if (!locked) {
2976 ret |= VM_FAULT_RETRY;
2977 goto out_release;
2978 }
2979
2980 /*
2981 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2982 * release the swapcache from under us. The page pin, and pte_same
2983 * test below, are not enough to exclude that. Even if it is still
2984 * swapcache, we need to check that the page's swap has not changed.
2985 */
2986 if (unlikely((!PageSwapCache(page) ||
2987 page_private(page) != entry.val)) && swapcache)
2988 goto out_page;
2989
2990 page = ksm_might_need_to_copy(page, vma, vmf->address);
2991 if (unlikely(!page)) {
2992 ret = VM_FAULT_OOM;
2993 page = swapcache;
2994 goto out_page;
2995 }
2996
2997 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2998 &memcg, false)) {
2999 ret = VM_FAULT_OOM;
3000 goto out_page;
3001 }
3002
3003 /*
3004 * Back out if somebody else already faulted in this pte.
3005 */
3006 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3007 &vmf->ptl);
3008 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3009 goto out_nomap;
3010
3011 if (unlikely(!PageUptodate(page))) {
3012 ret = VM_FAULT_SIGBUS;
3013 goto out_nomap;
3014 }
3015
3016 /*
3017 * The page isn't present yet, go ahead with the fault.
3018 *
3019 * Be careful about the sequence of operations here.
3020 * To get its accounting right, reuse_swap_page() must be called
3021 * while the page is counted on swap but not yet in mapcount i.e.
3022 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3023 * must be called after the swap_free(), or it will never succeed.
3024 */
3025
3026 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3027 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3028 pte = mk_pte(page, vma->vm_page_prot);
3029 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
3030 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3031 vmf->flags &= ~FAULT_FLAG_WRITE;
3032 ret |= VM_FAULT_WRITE;
3033 exclusive = RMAP_EXCLUSIVE;
3034 }
3035 flush_icache_page(vma, page);
3036 if (pte_swp_soft_dirty(vmf->orig_pte))
3037 pte = pte_mksoft_dirty(pte);
3038 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3039 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3040 vmf->orig_pte = pte;
3041
3042 /* ksm created a completely new copy */
3043 if (unlikely(page != swapcache && swapcache)) {
3044 page_add_new_anon_rmap(page, vma, vmf->address, false);
3045 mem_cgroup_commit_charge(page, memcg, false, false);
3046 lru_cache_add_active_or_unevictable(page, vma);
3047 } else {
3048 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3049 mem_cgroup_commit_charge(page, memcg, true, false);
3050 activate_page(page);
3051 }
3052
3053 swap_free(entry);
3054 if (mem_cgroup_swap_full(page) ||
3055 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3056 try_to_free_swap(page);
3057 unlock_page(page);
3058 if (page != swapcache && swapcache) {
3059 /*
3060 * Hold the lock to avoid the swap entry to be reused
3061 * until we take the PT lock for the pte_same() check
3062 * (to avoid false positives from pte_same). For
3063 * further safety release the lock after the swap_free
3064 * so that the swap count won't change under a
3065 * parallel locked swapcache.
3066 */
3067 unlock_page(swapcache);
3068 put_page(swapcache);
3069 }
3070
3071 if (vmf->flags & FAULT_FLAG_WRITE) {
3072 ret |= do_wp_page(vmf);
3073 if (ret & VM_FAULT_ERROR)
3074 ret &= VM_FAULT_ERROR;
3075 goto out;
3076 }
3077
3078 /* No need to invalidate - it was non-present before */
3079 update_mmu_cache(vma, vmf->address, vmf->pte);
3080unlock:
3081 pte_unmap_unlock(vmf->pte, vmf->ptl);
3082out:
3083 return ret;
3084out_nomap:
3085 mem_cgroup_cancel_charge(page, memcg, false);
3086 pte_unmap_unlock(vmf->pte, vmf->ptl);
3087out_page:
3088 unlock_page(page);
3089out_release:
3090 put_page(page);
3091 if (page != swapcache && swapcache) {
3092 unlock_page(swapcache);
3093 put_page(swapcache);
3094 }
3095 return ret;
3096}
3097
3098/*
3099 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3100 * but allow concurrent faults), and pte mapped but not yet locked.
3101 * We return with mmap_sem still held, but pte unmapped and unlocked.
3102 */
3103static int do_anonymous_page(struct vm_fault *vmf)
3104{
3105 struct vm_area_struct *vma = vmf->vma;
3106 struct mem_cgroup *memcg;
3107 struct page *page;
3108 int ret = 0;
3109 pte_t entry;
3110
3111 /* File mapping without ->vm_ops ? */
3112 if (vma->vm_flags & VM_SHARED)
3113 return VM_FAULT_SIGBUS;
3114
3115 /*
3116 * Use pte_alloc() instead of pte_alloc_map(). We can't run
3117 * pte_offset_map() on pmds where a huge pmd might be created
3118 * from a different thread.
3119 *
3120 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
3121 * parallel threads are excluded by other means.
3122 *
3123 * Here we only have down_read(mmap_sem).
3124 */
3125 if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
3126 return VM_FAULT_OOM;
3127
3128 /* See the comment in pte_alloc_one_map() */
3129 if (unlikely(pmd_trans_unstable(vmf->pmd)))
3130 return 0;
3131
3132 /* Use the zero-page for reads */
3133 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3134 !mm_forbids_zeropage(vma->vm_mm)) {
3135 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3136 vma->vm_page_prot));
3137 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3138 vmf->address, &vmf->ptl);
3139 if (!pte_none(*vmf->pte))
3140 goto unlock;
3141 ret = check_stable_address_space(vma->vm_mm);
3142 if (ret)
3143 goto unlock;
3144 /* Deliver the page fault to userland, check inside PT lock */
3145 if (userfaultfd_missing(vma)) {
3146 pte_unmap_unlock(vmf->pte, vmf->ptl);
3147 return handle_userfault(vmf, VM_UFFD_MISSING);
3148 }
3149 goto setpte;
3150 }
3151
3152 /* Allocate our own private page. */
3153 if (unlikely(anon_vma_prepare(vma)))
3154 goto oom;
3155 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3156 if (!page)
3157 goto oom;
3158
3159 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
3160 goto oom_free_page;
3161
3162 /*
3163 * The memory barrier inside __SetPageUptodate makes sure that
3164 * preceeding stores to the page contents become visible before
3165 * the set_pte_at() write.
3166 */
3167 __SetPageUptodate(page);
3168
3169 entry = mk_pte(page, vma->vm_page_prot);
3170 if (vma->vm_flags & VM_WRITE)
3171 entry = pte_mkwrite(pte_mkdirty(entry));
3172
3173 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3174 &vmf->ptl);
3175 if (!pte_none(*vmf->pte))
3176 goto release;
3177
3178 ret = check_stable_address_space(vma->vm_mm);
3179 if (ret)
3180 goto release;
3181
3182 /* Deliver the page fault to userland, check inside PT lock */
3183 if (userfaultfd_missing(vma)) {
3184 pte_unmap_unlock(vmf->pte, vmf->ptl);
3185 mem_cgroup_cancel_charge(page, memcg, false);
3186 put_page(page);
3187 return handle_userfault(vmf, VM_UFFD_MISSING);
3188 }
3189
3190 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3191 page_add_new_anon_rmap(page, vma, vmf->address, false);
3192 mem_cgroup_commit_charge(page, memcg, false, false);
3193 lru_cache_add_active_or_unevictable(page, vma);
3194setpte:
3195 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3196
3197 /* No need to invalidate - it was non-present before */
3198 update_mmu_cache(vma, vmf->address, vmf->pte);
3199unlock:
3200 pte_unmap_unlock(vmf->pte, vmf->ptl);
3201 return ret;
3202release:
3203 mem_cgroup_cancel_charge(page, memcg, false);
3204 put_page(page);
3205 goto unlock;
3206oom_free_page:
3207 put_page(page);
3208oom:
3209 return VM_FAULT_OOM;
3210}
3211
3212/*
3213 * The mmap_sem must have been held on entry, and may have been
3214 * released depending on flags and vma->vm_ops->fault() return value.
3215 * See filemap_fault() and __lock_page_retry().
3216 */
3217static int __do_fault(struct vm_fault *vmf)
3218{
3219 struct vm_area_struct *vma = vmf->vma;
3220 int ret;
3221
3222 ret = vma->vm_ops->fault(vmf);
3223 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3224 VM_FAULT_DONE_COW)))
3225 return ret;
3226
3227 if (unlikely(PageHWPoison(vmf->page))) {
3228 if (ret & VM_FAULT_LOCKED)
3229 unlock_page(vmf->page);
3230 put_page(vmf->page);
3231 vmf->page = NULL;
3232 return VM_FAULT_HWPOISON;
3233 }
3234
3235 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3236 lock_page(vmf->page);
3237 else
3238 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3239
3240 return ret;
3241}
3242
3243/*
3244 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3245 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3246 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3247 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3248 */
3249static int pmd_devmap_trans_unstable(pmd_t *pmd)
3250{
3251 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3252}
3253
3254static int pte_alloc_one_map(struct vm_fault *vmf)
3255{
3256 struct vm_area_struct *vma = vmf->vma;
3257
3258 if (!pmd_none(*vmf->pmd))
3259 goto map_pte;
3260 if (vmf->prealloc_pte) {
3261 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3262 if (unlikely(!pmd_none(*vmf->pmd))) {
3263 spin_unlock(vmf->ptl);
3264 goto map_pte;
3265 }
3266
3267 mm_inc_nr_ptes(vma->vm_mm);
3268 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3269 spin_unlock(vmf->ptl);
3270 vmf->prealloc_pte = NULL;
3271 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3272 return VM_FAULT_OOM;
3273 }
3274map_pte:
3275 /*
3276 * If a huge pmd materialized under us just retry later. Use
3277 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3278 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3279 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3280 * running immediately after a huge pmd fault in a different thread of
3281 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3282 * All we have to ensure is that it is a regular pmd that we can walk
3283 * with pte_offset_map() and we can do that through an atomic read in
3284 * C, which is what pmd_trans_unstable() provides.
3285 */
3286 if (pmd_devmap_trans_unstable(vmf->pmd))
3287 return VM_FAULT_NOPAGE;
3288
3289 /*
3290 * At this point we know that our vmf->pmd points to a page of ptes
3291 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3292 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3293 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3294 * be valid and we will re-check to make sure the vmf->pte isn't
3295 * pte_none() under vmf->ptl protection when we return to
3296 * alloc_set_pte().
3297 */
3298 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3299 &vmf->ptl);
3300 return 0;
3301}
3302
3303#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3304
3305#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3306static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3307 unsigned long haddr)
3308{
3309 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3310 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3311 return false;
3312 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3313 return false;
3314 return true;
3315}
3316
3317static void deposit_prealloc_pte(struct vm_fault *vmf)
3318{
3319 struct vm_area_struct *vma = vmf->vma;
3320
3321 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3322 /*
3323 * We are going to consume the prealloc table,
3324 * count that as nr_ptes.
3325 */
3326 mm_inc_nr_ptes(vma->vm_mm);
3327 vmf->prealloc_pte = NULL;
3328}
3329
3330static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3331{
3332 struct vm_area_struct *vma = vmf->vma;
3333 bool write = vmf->flags & FAULT_FLAG_WRITE;
3334 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3335 pmd_t entry;
3336 int i, ret;
3337
3338 if (!transhuge_vma_suitable(vma, haddr))
3339 return VM_FAULT_FALLBACK;
3340
3341 ret = VM_FAULT_FALLBACK;
3342 page = compound_head(page);
3343
3344 /*
3345 * Archs like ppc64 need additonal space to store information
3346 * related to pte entry. Use the preallocated table for that.
3347 */
3348 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3349 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3350 if (!vmf->prealloc_pte)
3351 return VM_FAULT_OOM;
3352 smp_wmb(); /* See comment in __pte_alloc() */
3353 }
3354
3355 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3356 if (unlikely(!pmd_none(*vmf->pmd)))
3357 goto out;
3358
3359 for (i = 0; i < HPAGE_PMD_NR; i++)
3360 flush_icache_page(vma, page + i);
3361
3362 entry = mk_huge_pmd(page, vma->vm_page_prot);
3363 if (write)
3364 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3365
3366 add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3367 page_add_file_rmap(page, true);
3368 /*
3369 * deposit and withdraw with pmd lock held
3370 */
3371 if (arch_needs_pgtable_deposit())
3372 deposit_prealloc_pte(vmf);
3373
3374 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3375
3376 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3377
3378 /* fault is handled */
3379 ret = 0;
3380 count_vm_event(THP_FILE_MAPPED);
3381out:
3382 spin_unlock(vmf->ptl);
3383 return ret;
3384}
3385#else
3386static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3387{
3388 BUILD_BUG();
3389 return 0;
3390}
3391#endif
3392
3393/**
3394 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3395 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3396 *
3397 * @vmf: fault environment
3398 * @memcg: memcg to charge page (only for private mappings)
3399 * @page: page to map
3400 *
3401 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3402 * return.
3403 *
3404 * Target users are page handler itself and implementations of
3405 * vm_ops->map_pages.
3406 */
3407int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3408 struct page *page)
3409{
3410 struct vm_area_struct *vma = vmf->vma;
3411 bool write = vmf->flags & FAULT_FLAG_WRITE;
3412 pte_t entry;
3413 int ret;
3414
3415 if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3416 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3417 /* THP on COW? */
3418 VM_BUG_ON_PAGE(memcg, page);
3419
3420 ret = do_set_pmd(vmf, page);
3421 if (ret != VM_FAULT_FALLBACK)
3422 return ret;
3423 }
3424
3425 if (!vmf->pte) {
3426 ret = pte_alloc_one_map(vmf);
3427 if (ret)
3428 return ret;
3429 }
3430
3431 /* Re-check under ptl */
3432 if (unlikely(!pte_none(*vmf->pte)))
3433 return VM_FAULT_NOPAGE;
3434
3435 flush_icache_page(vma, page);
3436 entry = mk_pte(page, vma->vm_page_prot);
3437 if (write)
3438 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3439 /* copy-on-write page */
3440 if (write && !(vma->vm_flags & VM_SHARED)) {
3441 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3442 page_add_new_anon_rmap(page, vma, vmf->address, false);
3443 mem_cgroup_commit_charge(page, memcg, false, false);
3444 lru_cache_add_active_or_unevictable(page, vma);
3445 } else {
3446 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3447 page_add_file_rmap(page, false);
3448 }
3449 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3450
3451 /* no need to invalidate: a not-present page won't be cached */
3452 update_mmu_cache(vma, vmf->address, vmf->pte);
3453
3454 return 0;
3455}
3456
3457
3458/**
3459 * finish_fault - finish page fault once we have prepared the page to fault
3460 *
3461 * @vmf: structure describing the fault
3462 *
3463 * This function handles all that is needed to finish a page fault once the
3464 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3465 * given page, adds reverse page mapping, handles memcg charges and LRU
3466 * addition. The function returns 0 on success, VM_FAULT_ code in case of
3467 * error.
3468 *
3469 * The function expects the page to be locked and on success it consumes a
3470 * reference of a page being mapped (for the PTE which maps it).
3471 */
3472int finish_fault(struct vm_fault *vmf)
3473{
3474 struct page *page;
3475 int ret = 0;
3476
3477 /* Did we COW the page? */
3478 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3479 !(vmf->vma->vm_flags & VM_SHARED))
3480 page = vmf->cow_page;
3481 else
3482 page = vmf->page;
3483
3484 /*
3485 * check even for read faults because we might have lost our CoWed
3486 * page
3487 */
3488 if (!(vmf->vma->vm_flags & VM_SHARED))
3489 ret = check_stable_address_space(vmf->vma->vm_mm);
3490 if (!ret)
3491 ret = alloc_set_pte(vmf, vmf->memcg, page);
3492 if (vmf->pte)
3493 pte_unmap_unlock(vmf->pte, vmf->ptl);
3494 return ret;
3495}
3496
3497static unsigned long fault_around_bytes __read_mostly =
3498 rounddown_pow_of_two(65536);
3499
3500#ifdef CONFIG_DEBUG_FS
3501static int fault_around_bytes_get(void *data, u64 *val)
3502{
3503 *val = fault_around_bytes;
3504 return 0;
3505}
3506
3507/*
3508 * fault_around_bytes must be rounded down to the nearest page order as it's
3509 * what do_fault_around() expects to see.
3510 */
3511static int fault_around_bytes_set(void *data, u64 val)
3512{
3513 if (val / PAGE_SIZE > PTRS_PER_PTE)
3514 return -EINVAL;
3515 if (val > PAGE_SIZE)
3516 fault_around_bytes = rounddown_pow_of_two(val);
3517 else
3518 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3519 return 0;
3520}
3521DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3522 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3523
3524static int __init fault_around_debugfs(void)
3525{
3526 void *ret;
3527
3528 ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3529 &fault_around_bytes_fops);
3530 if (!ret)
3531 pr_warn("Failed to create fault_around_bytes in debugfs");
3532 return 0;
3533}
3534late_initcall(fault_around_debugfs);
3535#endif
3536
3537/*
3538 * do_fault_around() tries to map few pages around the fault address. The hope
3539 * is that the pages will be needed soon and this will lower the number of
3540 * faults to handle.
3541 *
3542 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3543 * not ready to be mapped: not up-to-date, locked, etc.
3544 *
3545 * This function is called with the page table lock taken. In the split ptlock
3546 * case the page table lock only protects only those entries which belong to
3547 * the page table corresponding to the fault address.
3548 *
3549 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3550 * only once.
3551 *
3552 * fault_around_bytes defines how many bytes we'll try to map.
3553 * do_fault_around() expects it to be set to a power of two less than or equal
3554 * to PTRS_PER_PTE.
3555 *
3556 * The virtual address of the area that we map is naturally aligned to
3557 * fault_around_bytes rounded down to the machine page size
3558 * (and therefore to page order). This way it's easier to guarantee
3559 * that we don't cross page table boundaries.
3560 */
3561static int do_fault_around(struct vm_fault *vmf)
3562{
3563 unsigned long address = vmf->address, nr_pages, mask;
3564 pgoff_t start_pgoff = vmf->pgoff;
3565 pgoff_t end_pgoff;
3566 int off, ret = 0;
3567
3568 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3569 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3570
3571 vmf->address = max(address & mask, vmf->vma->vm_start);
3572 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3573 start_pgoff -= off;
3574
3575 /*
3576 * end_pgoff is either the end of the page table, the end of
3577 * the vma or nr_pages from start_pgoff, depending what is nearest.
3578 */
3579 end_pgoff = start_pgoff -
3580 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3581 PTRS_PER_PTE - 1;
3582 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3583 start_pgoff + nr_pages - 1);
3584
3585 if (pmd_none(*vmf->pmd)) {
3586 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3587 vmf->address);
3588 if (!vmf->prealloc_pte)
3589 goto out;
3590 smp_wmb(); /* See comment in __pte_alloc() */
3591 }
3592
3593 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3594
3595 /* Huge page is mapped? Page fault is solved */
3596 if (pmd_trans_huge(*vmf->pmd)) {
3597 ret = VM_FAULT_NOPAGE;
3598 goto out;
3599 }
3600
3601 /* ->map_pages() haven't done anything useful. Cold page cache? */
3602 if (!vmf->pte)
3603 goto out;
3604
3605 /* check if the page fault is solved */
3606 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3607 if (!pte_none(*vmf->pte))
3608 ret = VM_FAULT_NOPAGE;
3609 pte_unmap_unlock(vmf->pte, vmf->ptl);
3610out:
3611 vmf->address = address;
3612 vmf->pte = NULL;
3613 return ret;
3614}
3615
3616static int do_read_fault(struct vm_fault *vmf)
3617{
3618 struct vm_area_struct *vma = vmf->vma;
3619 int ret = 0;
3620
3621 /*
3622 * Let's call ->map_pages() first and use ->fault() as fallback
3623 * if page by the offset is not ready to be mapped (cold cache or
3624 * something).
3625 */
3626 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3627 ret = do_fault_around(vmf);
3628 if (ret)
3629 return ret;
3630 }
3631
3632 ret = __do_fault(vmf);
3633 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3634 return ret;
3635
3636 ret |= finish_fault(vmf);
3637 unlock_page(vmf->page);
3638 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3639 put_page(vmf->page);
3640 return ret;
3641}
3642
3643static int do_cow_fault(struct vm_fault *vmf)
3644{
3645 struct vm_area_struct *vma = vmf->vma;
3646 int ret;
3647
3648 if (unlikely(anon_vma_prepare(vma)))
3649 return VM_FAULT_OOM;
3650
3651 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3652 if (!vmf->cow_page)
3653 return VM_FAULT_OOM;
3654
3655 if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3656 &vmf->memcg, false)) {
3657 put_page(vmf->cow_page);
3658 return VM_FAULT_OOM;
3659 }
3660
3661 ret = __do_fault(vmf);
3662 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3663 goto uncharge_out;
3664 if (ret & VM_FAULT_DONE_COW)
3665 return ret;
3666
3667 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3668 __SetPageUptodate(vmf->cow_page);
3669
3670 ret |= finish_fault(vmf);
3671 unlock_page(vmf->page);
3672 put_page(vmf->page);
3673 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3674 goto uncharge_out;
3675 return ret;
3676uncharge_out:
3677 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3678 put_page(vmf->cow_page);
3679 return ret;
3680}
3681
3682static int do_shared_fault(struct vm_fault *vmf)
3683{
3684 struct vm_area_struct *vma = vmf->vma;
3685 int ret, tmp;
3686
3687 ret = __do_fault(vmf);
3688 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3689 return ret;
3690
3691 /*
3692 * Check if the backing address space wants to know that the page is
3693 * about to become writable
3694 */
3695 if (vma->vm_ops->page_mkwrite) {
3696 unlock_page(vmf->page);
3697 tmp = do_page_mkwrite(vmf);
3698 if (unlikely(!tmp ||
3699 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3700 put_page(vmf->page);
3701 return tmp;
3702 }
3703 }
3704
3705 ret |= finish_fault(vmf);
3706 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3707 VM_FAULT_RETRY))) {
3708 unlock_page(vmf->page);
3709 put_page(vmf->page);
3710 return ret;
3711 }
3712
3713 fault_dirty_shared_page(vma, vmf->page);
3714 return ret;
3715}
3716
3717/*
3718 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3719 * but allow concurrent faults).
3720 * The mmap_sem may have been released depending on flags and our
3721 * return value. See filemap_fault() and __lock_page_or_retry().
3722 */
3723static int do_fault(struct vm_fault *vmf)
3724{
3725 struct vm_area_struct *vma = vmf->vma;
3726 int ret;
3727
3728 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3729 if (!vma->vm_ops->fault)
3730 ret = VM_FAULT_SIGBUS;
3731 else if (!(vmf->flags & FAULT_FLAG_WRITE))
3732 ret = do_read_fault(vmf);
3733 else if (!(vma->vm_flags & VM_SHARED))
3734 ret = do_cow_fault(vmf);
3735 else
3736 ret = do_shared_fault(vmf);
3737
3738 /* preallocated pagetable is unused: free it */
3739 if (vmf->prealloc_pte) {
3740 pte_free(vma->vm_mm, vmf->prealloc_pte);
3741 vmf->prealloc_pte = NULL;
3742 }
3743 return ret;
3744}
3745
3746static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3747 unsigned long addr, int page_nid,
3748 int *flags)
3749{
3750 get_page(page);
3751
3752 count_vm_numa_event(NUMA_HINT_FAULTS);
3753 if (page_nid == numa_node_id()) {
3754 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3755 *flags |= TNF_FAULT_LOCAL;
3756 }
3757
3758 return mpol_misplaced(page, vma, addr);
3759}
3760
3761static int do_numa_page(struct vm_fault *vmf)
3762{
3763 struct vm_area_struct *vma = vmf->vma;
3764 struct page *page = NULL;
3765 int page_nid = -1;
3766 int last_cpupid;
3767 int target_nid;
3768 bool migrated = false;
3769 pte_t pte;
3770 bool was_writable = pte_savedwrite(vmf->orig_pte);
3771 int flags = 0;
3772
3773 /*
3774 * The "pte" at this point cannot be used safely without
3775 * validation through pte_unmap_same(). It's of NUMA type but
3776 * the pfn may be screwed if the read is non atomic.
3777 */
3778 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3779 spin_lock(vmf->ptl);
3780 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3781 pte_unmap_unlock(vmf->pte, vmf->ptl);
3782 goto out;
3783 }
3784
3785 /*
3786 * Make it present again, Depending on how arch implementes non
3787 * accessible ptes, some can allow access by kernel mode.
3788 */
3789 pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3790 pte = pte_modify(pte, vma->vm_page_prot);
3791 pte = pte_mkyoung(pte);
3792 if (was_writable)
3793 pte = pte_mkwrite(pte);
3794 ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3795 update_mmu_cache(vma, vmf->address, vmf->pte);
3796
3797 page = vm_normal_page(vma, vmf->address, pte);
3798 if (!page) {
3799 pte_unmap_unlock(vmf->pte, vmf->ptl);
3800 return 0;
3801 }
3802
3803 /* TODO: handle PTE-mapped THP */
3804 if (PageCompound(page)) {
3805 pte_unmap_unlock(vmf->pte, vmf->ptl);
3806 return 0;
3807 }
3808
3809 /*
3810 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3811 * much anyway since they can be in shared cache state. This misses
3812 * the case where a mapping is writable but the process never writes
3813 * to it but pte_write gets cleared during protection updates and
3814 * pte_dirty has unpredictable behaviour between PTE scan updates,
3815 * background writeback, dirty balancing and application behaviour.
3816 */
3817 if (!pte_write(pte))
3818 flags |= TNF_NO_GROUP;
3819
3820 /*
3821 * Flag if the page is shared between multiple address spaces. This
3822 * is later used when determining whether to group tasks together
3823 */
3824 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3825 flags |= TNF_SHARED;
3826
3827 last_cpupid = page_cpupid_last(page);
3828 page_nid = page_to_nid(page);
3829 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3830 &flags);
3831 pte_unmap_unlock(vmf->pte, vmf->ptl);
3832 if (target_nid == -1) {
3833 put_page(page);
3834 goto out;
3835 }
3836
3837 /* Migrate to the requested node */
3838 migrated = migrate_misplaced_page(page, vma, target_nid);
3839 if (migrated) {
3840 page_nid = target_nid;
3841 flags |= TNF_MIGRATED;
3842 } else
3843 flags |= TNF_MIGRATE_FAIL;
3844
3845out:
3846 if (page_nid != -1)
3847 task_numa_fault(last_cpupid, page_nid, 1, flags);
3848 return 0;
3849}
3850
3851static inline int create_huge_pmd(struct vm_fault *vmf)
3852{
3853 if (vma_is_anonymous(vmf->vma))
3854 return do_huge_pmd_anonymous_page(vmf);
3855 if (vmf->vma->vm_ops->huge_fault)
3856 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3857 return VM_FAULT_FALLBACK;
3858}
3859
3860/* `inline' is required to avoid gcc 4.1.2 build error */
3861static inline int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3862{
3863 if (vma_is_anonymous(vmf->vma))
3864 return do_huge_pmd_wp_page(vmf, orig_pmd);
3865 if (vmf->vma->vm_ops->huge_fault)
3866 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3867
3868 /* COW handled on pte level: split pmd */
3869 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3870 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3871
3872 return VM_FAULT_FALLBACK;
3873}
3874
3875static inline bool vma_is_accessible(struct vm_area_struct *vma)
3876{
3877 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3878}
3879
3880static int create_huge_pud(struct vm_fault *vmf)
3881{
3882#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3883 /* No support for anonymous transparent PUD pages yet */
3884 if (vma_is_anonymous(vmf->vma))
3885 return VM_FAULT_FALLBACK;
3886 if (vmf->vma->vm_ops->huge_fault)
3887 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3888#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3889 return VM_FAULT_FALLBACK;
3890}
3891
3892static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3893{
3894#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3895 /* No support for anonymous transparent PUD pages yet */
3896 if (vma_is_anonymous(vmf->vma))
3897 return VM_FAULT_FALLBACK;
3898 if (vmf->vma->vm_ops->huge_fault)
3899 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3900#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3901 return VM_FAULT_FALLBACK;
3902}
3903
3904/*
3905 * These routines also need to handle stuff like marking pages dirty
3906 * and/or accessed for architectures that don't do it in hardware (most
3907 * RISC architectures). The early dirtying is also good on the i386.
3908 *
3909 * There is also a hook called "update_mmu_cache()" that architectures
3910 * with external mmu caches can use to update those (ie the Sparc or
3911 * PowerPC hashed page tables that act as extended TLBs).
3912 *
3913 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3914 * concurrent faults).
3915 *
3916 * The mmap_sem may have been released depending on flags and our return value.
3917 * See filemap_fault() and __lock_page_or_retry().
3918 */
3919static int handle_pte_fault(struct vm_fault *vmf)
3920{
3921 pte_t entry;
3922
3923 if (unlikely(pmd_none(*vmf->pmd))) {
3924 /*
3925 * Leave __pte_alloc() until later: because vm_ops->fault may
3926 * want to allocate huge page, and if we expose page table
3927 * for an instant, it will be difficult to retract from
3928 * concurrent faults and from rmap lookups.
3929 */
3930 vmf->pte = NULL;
3931 } else {
3932 /* See comment in pte_alloc_one_map() */
3933 if (pmd_devmap_trans_unstable(vmf->pmd))
3934 return 0;
3935 /*
3936 * A regular pmd is established and it can't morph into a huge
3937 * pmd from under us anymore at this point because we hold the
3938 * mmap_sem read mode and khugepaged takes it in write mode.
3939 * So now it's safe to run pte_offset_map().
3940 */
3941 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3942 vmf->orig_pte = *vmf->pte;
3943
3944 /*
3945 * some architectures can have larger ptes than wordsize,
3946 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3947 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
3948 * accesses. The code below just needs a consistent view
3949 * for the ifs and we later double check anyway with the
3950 * ptl lock held. So here a barrier will do.
3951 */
3952 barrier();
3953 if (pte_none(vmf->orig_pte)) {
3954 pte_unmap(vmf->pte);
3955 vmf->pte = NULL;
3956 }
3957 }
3958
3959 if (!vmf->pte) {
3960 if (vma_is_anonymous(vmf->vma))
3961 return do_anonymous_page(vmf);
3962 else
3963 return do_fault(vmf);
3964 }
3965
3966 if (!pte_present(vmf->orig_pte))
3967 return do_swap_page(vmf);
3968
3969 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3970 return do_numa_page(vmf);
3971
3972 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3973 spin_lock(vmf->ptl);
3974 entry = vmf->orig_pte;
3975 if (unlikely(!pte_same(*vmf->pte, entry)))
3976 goto unlock;
3977 if (vmf->flags & FAULT_FLAG_WRITE) {
3978 if (!pte_write(entry))
3979 return do_wp_page(vmf);
3980 entry = pte_mkdirty(entry);
3981 }
3982 entry = pte_mkyoung(entry);
3983 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3984 vmf->flags & FAULT_FLAG_WRITE)) {
3985 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3986 } else {
3987 /*
3988 * This is needed only for protection faults but the arch code
3989 * is not yet telling us if this is a protection fault or not.
3990 * This still avoids useless tlb flushes for .text page faults
3991 * with threads.
3992 */
3993 if (vmf->flags & FAULT_FLAG_WRITE)
3994 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3995 }
3996unlock:
3997 pte_unmap_unlock(vmf->pte, vmf->ptl);
3998 return 0;
3999}
4000
4001/*
4002 * By the time we get here, we already hold the mm semaphore
4003 *
4004 * The mmap_sem may have been released depending on flags and our
4005 * return value. See filemap_fault() and __lock_page_or_retry().
4006 */
4007static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4008 unsigned int flags)
4009{
4010 struct vm_fault vmf = {
4011 .vma = vma,
4012 .address = address & PAGE_MASK,
4013 .flags = flags,
4014 .pgoff = linear_page_index(vma, address),
4015 .gfp_mask = __get_fault_gfp_mask(vma),
4016 };
4017 unsigned int dirty = flags & FAULT_FLAG_WRITE;
4018 struct mm_struct *mm = vma->vm_mm;
4019 pgd_t *pgd;
4020 p4d_t *p4d;
4021 int ret;
4022
4023 pgd = pgd_offset(mm, address);
4024 p4d = p4d_alloc(mm, pgd, address);
4025 if (!p4d)
4026 return VM_FAULT_OOM;
4027
4028 vmf.pud = pud_alloc(mm, p4d, address);
4029 if (!vmf.pud)
4030 return VM_FAULT_OOM;
4031 if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
4032 ret = create_huge_pud(&vmf);
4033 if (!(ret & VM_FAULT_FALLBACK))
4034 return ret;
4035 } else {
4036 pud_t orig_pud = *vmf.pud;
4037
4038 barrier();
4039 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4040
4041 /* NUMA case for anonymous PUDs would go here */
4042
4043 if (dirty && !pud_write(orig_pud)) {
4044 ret = wp_huge_pud(&vmf, orig_pud);
4045 if (!(ret & VM_FAULT_FALLBACK))
4046 return ret;
4047 } else {
4048 huge_pud_set_accessed(&vmf, orig_pud);
4049 return 0;
4050 }
4051 }
4052 }
4053
4054 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4055 if (!vmf.pmd)
4056 return VM_FAULT_OOM;
4057 if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
4058 ret = create_huge_pmd(&vmf);
4059 if (!(ret & VM_FAULT_FALLBACK))
4060 return ret;
4061 } else {
4062 pmd_t orig_pmd = *vmf.pmd;
4063
4064 barrier();
4065 if (unlikely(is_swap_pmd(orig_pmd))) {
4066 VM_BUG_ON(thp_migration_supported() &&
4067 !is_pmd_migration_entry(orig_pmd));
4068 if (is_pmd_migration_entry(orig_pmd))
4069 pmd_migration_entry_wait(mm, vmf.pmd);
4070 return 0;
4071 }
4072 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
4073 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
4074 return do_huge_pmd_numa_page(&vmf, orig_pmd);
4075
4076 if (dirty && !pmd_write(orig_pmd)) {
4077 ret = wp_huge_pmd(&vmf, orig_pmd);
4078 if (!(ret & VM_FAULT_FALLBACK))
4079 return ret;
4080 } else {
4081 huge_pmd_set_accessed(&vmf, orig_pmd);
4082 return 0;
4083 }
4084 }
4085 }
4086
4087 return handle_pte_fault(&vmf);
4088}
4089
4090/*
4091 * By the time we get here, we already hold the mm semaphore
4092 *
4093 * The mmap_sem may have been released depending on flags and our
4094 * return value. See filemap_fault() and __lock_page_or_retry().
4095 */
4096int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4097 unsigned int flags)
4098{
4099 int ret;
4100
4101 __set_current_state(TASK_RUNNING);
4102
4103 count_vm_event(PGFAULT);
4104 count_memcg_event_mm(vma->vm_mm, PGFAULT);
4105
4106 /* do counter updates before entering really critical section. */
4107 check_sync_rss_stat(current);
4108
4109 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4110 flags & FAULT_FLAG_INSTRUCTION,
4111 flags & FAULT_FLAG_REMOTE))
4112 return VM_FAULT_SIGSEGV;
4113
4114 /*
4115 * Enable the memcg OOM handling for faults triggered in user
4116 * space. Kernel faults are handled more gracefully.
4117 */
4118 if (flags & FAULT_FLAG_USER)
4119 mem_cgroup_oom_enable();
4120
4121 if (unlikely(is_vm_hugetlb_page(vma)))
4122 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4123 else
4124 ret = __handle_mm_fault(vma, address, flags);
4125
4126 if (flags & FAULT_FLAG_USER) {
4127 mem_cgroup_oom_disable();
4128 /*
4129 * The task may have entered a memcg OOM situation but
4130 * if the allocation error was handled gracefully (no
4131 * VM_FAULT_OOM), there is no need to kill anything.
4132 * Just clean up the OOM state peacefully.
4133 */
4134 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4135 mem_cgroup_oom_synchronize(false);
4136 }
4137
4138 return ret;
4139}
4140EXPORT_SYMBOL_GPL(handle_mm_fault);
4141
4142#ifndef __PAGETABLE_P4D_FOLDED
4143/*
4144 * Allocate p4d page table.
4145 * We've already handled the fast-path in-line.
4146 */
4147int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4148{
4149 p4d_t *new = p4d_alloc_one(mm, address);
4150 if (!new)
4151 return -ENOMEM;
4152
4153 smp_wmb(); /* See comment in __pte_alloc */
4154
4155 spin_lock(&mm->page_table_lock);
4156 if (pgd_present(*pgd)) /* Another has populated it */
4157 p4d_free(mm, new);
4158 else
4159 pgd_populate(mm, pgd, new);
4160 spin_unlock(&mm->page_table_lock);
4161 return 0;
4162}
4163#endif /* __PAGETABLE_P4D_FOLDED */
4164
4165#ifndef __PAGETABLE_PUD_FOLDED
4166/*
4167 * Allocate page upper directory.
4168 * We've already handled the fast-path in-line.
4169 */
4170int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4171{
4172 pud_t *new = pud_alloc_one(mm, address);
4173 if (!new)
4174 return -ENOMEM;
4175
4176 smp_wmb(); /* See comment in __pte_alloc */
4177
4178 spin_lock(&mm->page_table_lock);
4179#ifndef __ARCH_HAS_5LEVEL_HACK
4180 if (!p4d_present(*p4d)) {
4181 mm_inc_nr_puds(mm);
4182 p4d_populate(mm, p4d, new);
4183 } else /* Another has populated it */
4184 pud_free(mm, new);
4185#else
4186 if (!pgd_present(*p4d)) {
4187 mm_inc_nr_puds(mm);
4188 pgd_populate(mm, p4d, new);
4189 } else /* Another has populated it */
4190 pud_free(mm, new);
4191#endif /* __ARCH_HAS_5LEVEL_HACK */
4192 spin_unlock(&mm->page_table_lock);
4193 return 0;
4194}
4195#endif /* __PAGETABLE_PUD_FOLDED */
4196
4197#ifndef __PAGETABLE_PMD_FOLDED
4198/*
4199 * Allocate page middle directory.
4200 * We've already handled the fast-path in-line.
4201 */
4202int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4203{
4204 spinlock_t *ptl;
4205 pmd_t *new = pmd_alloc_one(mm, address);
4206 if (!new)
4207 return -ENOMEM;
4208
4209 smp_wmb(); /* See comment in __pte_alloc */
4210
4211 ptl = pud_lock(mm, pud);
4212#ifndef __ARCH_HAS_4LEVEL_HACK
4213 if (!pud_present(*pud)) {
4214 mm_inc_nr_pmds(mm);
4215 pud_populate(mm, pud, new);
4216 } else /* Another has populated it */
4217 pmd_free(mm, new);
4218#else
4219 if (!pgd_present(*pud)) {
4220 mm_inc_nr_pmds(mm);
4221 pgd_populate(mm, pud, new);
4222 } else /* Another has populated it */
4223 pmd_free(mm, new);
4224#endif /* __ARCH_HAS_4LEVEL_HACK */
4225 spin_unlock(ptl);
4226 return 0;
4227}
4228#endif /* __PAGETABLE_PMD_FOLDED */
4229
4230static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4231 unsigned long *start, unsigned long *end,
4232 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4233{
4234 pgd_t *pgd;
4235 p4d_t *p4d;
4236 pud_t *pud;
4237 pmd_t *pmd;
4238 pte_t *ptep;
4239
4240 pgd = pgd_offset(mm, address);
4241 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4242 goto out;
4243
4244 p4d = p4d_offset(pgd, address);
4245 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4246 goto out;
4247
4248 pud = pud_offset(p4d, address);
4249 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4250 goto out;
4251
4252 pmd = pmd_offset(pud, address);
4253 VM_BUG_ON(pmd_trans_huge(*pmd));
4254
4255 if (pmd_huge(*pmd)) {
4256 if (!pmdpp)
4257 goto out;
4258
4259 if (start && end) {
4260 *start = address & PMD_MASK;
4261 *end = *start + PMD_SIZE;
4262 mmu_notifier_invalidate_range_start(mm, *start, *end);
4263 }
4264 *ptlp = pmd_lock(mm, pmd);
4265 if (pmd_huge(*pmd)) {
4266 *pmdpp = pmd;
4267 return 0;
4268 }
4269 spin_unlock(*ptlp);
4270 if (start && end)
4271 mmu_notifier_invalidate_range_end(mm, *start, *end);
4272 }
4273
4274 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4275 goto out;
4276
4277 if (start && end) {
4278 *start = address & PAGE_MASK;
4279 *end = *start + PAGE_SIZE;
4280 mmu_notifier_invalidate_range_start(mm, *start, *end);
4281 }
4282 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4283 if (!pte_present(*ptep))
4284 goto unlock;
4285 *ptepp = ptep;
4286 return 0;
4287unlock:
4288 pte_unmap_unlock(ptep, *ptlp);
4289 if (start && end)
4290 mmu_notifier_invalidate_range_end(mm, *start, *end);
4291out:
4292 return -EINVAL;
4293}
4294
4295static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4296 pte_t **ptepp, spinlock_t **ptlp)
4297{
4298 int res;
4299
4300 /* (void) is needed to make gcc happy */
4301 (void) __cond_lock(*ptlp,
4302 !(res = __follow_pte_pmd(mm, address, NULL, NULL,
4303 ptepp, NULL, ptlp)));
4304 return res;
4305}
4306
4307int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4308 unsigned long *start, unsigned long *end,
4309 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4310{
4311 int res;
4312
4313 /* (void) is needed to make gcc happy */
4314 (void) __cond_lock(*ptlp,
4315 !(res = __follow_pte_pmd(mm, address, start, end,
4316 ptepp, pmdpp, ptlp)));
4317 return res;
4318}
4319EXPORT_SYMBOL(follow_pte_pmd);
4320
4321/**
4322 * follow_pfn - look up PFN at a user virtual address
4323 * @vma: memory mapping
4324 * @address: user virtual address
4325 * @pfn: location to store found PFN
4326 *
4327 * Only IO mappings and raw PFN mappings are allowed.
4328 *
4329 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4330 */
4331int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4332 unsigned long *pfn)
4333{
4334 int ret = -EINVAL;
4335 spinlock_t *ptl;
4336 pte_t *ptep;
4337
4338 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4339 return ret;
4340
4341 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4342 if (ret)
4343 return ret;
4344 *pfn = pte_pfn(*ptep);
4345 pte_unmap_unlock(ptep, ptl);
4346 return 0;
4347}
4348EXPORT_SYMBOL(follow_pfn);
4349
4350#ifdef CONFIG_HAVE_IOREMAP_PROT
4351int follow_phys(struct vm_area_struct *vma,
4352 unsigned long address, unsigned int flags,
4353 unsigned long *prot, resource_size_t *phys)
4354{
4355 int ret = -EINVAL;
4356 pte_t *ptep, pte;
4357 spinlock_t *ptl;
4358
4359 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4360 goto out;
4361
4362 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4363 goto out;
4364 pte = *ptep;
4365
4366 if ((flags & FOLL_WRITE) && !pte_write(pte))
4367 goto unlock;
4368
4369 *prot = pgprot_val(pte_pgprot(pte));
4370 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4371
4372 ret = 0;
4373unlock:
4374 pte_unmap_unlock(ptep, ptl);
4375out:
4376 return ret;
4377}
4378
4379int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4380 void *buf, int len, int write)
4381{
4382 resource_size_t phys_addr;
4383 unsigned long prot = 0;
4384 void __iomem *maddr;
4385 int offset = addr & (PAGE_SIZE-1);
4386
4387 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4388 return -EINVAL;
4389
4390 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4391 if (write)
4392 memcpy_toio(maddr + offset, buf, len);
4393 else
4394 memcpy_fromio(buf, maddr + offset, len);
4395 iounmap(maddr);
4396
4397 return len;
4398}
4399EXPORT_SYMBOL_GPL(generic_access_phys);
4400#endif
4401
4402/*
4403 * Access another process' address space as given in mm. If non-NULL, use the
4404 * given task for page fault accounting.
4405 */
4406int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4407 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4408{
4409 struct vm_area_struct *vma;
4410 void *old_buf = buf;
4411 int write = gup_flags & FOLL_WRITE;
4412
4413 down_read(&mm->mmap_sem);
4414 /* ignore errors, just check how much was successfully transferred */
4415 while (len) {
4416 int bytes, ret, offset;
4417 void *maddr;
4418 struct page *page = NULL;
4419
4420 ret = get_user_pages_remote(tsk, mm, addr, 1,
4421 gup_flags, &page, &vma, NULL);
4422 if (ret <= 0) {
4423#ifndef CONFIG_HAVE_IOREMAP_PROT
4424 break;
4425#else
4426 /*
4427 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4428 * we can access using slightly different code.
4429 */
4430 vma = find_vma(mm, addr);
4431 if (!vma || vma->vm_start > addr)
4432 break;
4433 if (vma->vm_ops && vma->vm_ops->access)
4434 ret = vma->vm_ops->access(vma, addr, buf,
4435 len, write);
4436 if (ret <= 0)
4437 break;
4438 bytes = ret;
4439#endif
4440 } else {
4441 bytes = len;
4442 offset = addr & (PAGE_SIZE-1);
4443 if (bytes > PAGE_SIZE-offset)
4444 bytes = PAGE_SIZE-offset;
4445
4446 maddr = kmap(page);
4447 if (write) {
4448 copy_to_user_page(vma, page, addr,
4449 maddr + offset, buf, bytes);
4450 set_page_dirty_lock(page);
4451 } else {
4452 copy_from_user_page(vma, page, addr,
4453 buf, maddr + offset, bytes);
4454 }
4455 kunmap(page);
4456 put_page(page);
4457 }
4458 len -= bytes;
4459 buf += bytes;
4460 addr += bytes;
4461 }
4462 up_read(&mm->mmap_sem);
4463
4464 return buf - old_buf;
4465}
4466
4467/**
4468 * access_remote_vm - access another process' address space
4469 * @mm: the mm_struct of the target address space
4470 * @addr: start address to access
4471 * @buf: source or destination buffer
4472 * @len: number of bytes to transfer
4473 * @gup_flags: flags modifying lookup behaviour
4474 *
4475 * The caller must hold a reference on @mm.
4476 */
4477int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4478 void *buf, int len, unsigned int gup_flags)
4479{
4480 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4481}
4482
4483/*
4484 * Access another process' address space.
4485 * Source/target buffer must be kernel space,
4486 * Do not walk the page table directly, use get_user_pages
4487 */
4488int access_process_vm(struct task_struct *tsk, unsigned long addr,
4489 void *buf, int len, unsigned int gup_flags)
4490{
4491 struct mm_struct *mm;
4492 int ret;
4493
4494 mm = get_task_mm(tsk);
4495 if (!mm)
4496 return 0;
4497
4498 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4499
4500 mmput(mm);
4501
4502 return ret;
4503}
4504EXPORT_SYMBOL_GPL(access_process_vm);
4505
4506/*
4507 * Print the name of a VMA.
4508 */
4509void print_vma_addr(char *prefix, unsigned long ip)
4510{
4511 struct mm_struct *mm = current->mm;
4512 struct vm_area_struct *vma;
4513
4514 /*
4515 * we might be running from an atomic context so we cannot sleep
4516 */
4517 if (!down_read_trylock(&mm->mmap_sem))
4518 return;
4519
4520 vma = find_vma(mm, ip);
4521 if (vma && vma->vm_file) {
4522 struct file *f = vma->vm_file;
4523 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4524 if (buf) {
4525 char *p;
4526
4527 p = file_path(f, buf, PAGE_SIZE);
4528 if (IS_ERR(p))
4529 p = "?";
4530 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4531 vma->vm_start,
4532 vma->vm_end - vma->vm_start);
4533 free_page((unsigned long)buf);
4534 }
4535 }
4536 up_read(&mm->mmap_sem);
4537}
4538
4539#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4540void __might_fault(const char *file, int line)
4541{
4542 /*
4543 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4544 * holding the mmap_sem, this is safe because kernel memory doesn't
4545 * get paged out, therefore we'll never actually fault, and the
4546 * below annotations will generate false positives.
4547 */
4548 if (uaccess_kernel())
4549 return;
4550 if (pagefault_disabled())
4551 return;
4552 __might_sleep(file, line, 0);
4553#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4554 if (current->mm)
4555 might_lock_read(¤t->mm->mmap_sem);
4556#endif
4557}
4558EXPORT_SYMBOL(__might_fault);
4559#endif
4560
4561#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4562static void clear_gigantic_page(struct page *page,
4563 unsigned long addr,
4564 unsigned int pages_per_huge_page)
4565{
4566 int i;
4567 struct page *p = page;
4568
4569 might_sleep();
4570 for (i = 0; i < pages_per_huge_page;
4571 i++, p = mem_map_next(p, page, i)) {
4572 cond_resched();
4573 clear_user_highpage(p, addr + i * PAGE_SIZE);
4574 }
4575}
4576void clear_huge_page(struct page *page,
4577 unsigned long addr_hint, unsigned int pages_per_huge_page)
4578{
4579 int i, n, base, l;
4580 unsigned long addr = addr_hint &
4581 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4582
4583 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4584 clear_gigantic_page(page, addr, pages_per_huge_page);
4585 return;
4586 }
4587
4588 /* Clear sub-page to access last to keep its cache lines hot */
4589 might_sleep();
4590 n = (addr_hint - addr) / PAGE_SIZE;
4591 if (2 * n <= pages_per_huge_page) {
4592 /* If sub-page to access in first half of huge page */
4593 base = 0;
4594 l = n;
4595 /* Clear sub-pages at the end of huge page */
4596 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4597 cond_resched();
4598 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4599 }
4600 } else {
4601 /* If sub-page to access in second half of huge page */
4602 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4603 l = pages_per_huge_page - n;
4604 /* Clear sub-pages at the begin of huge page */
4605 for (i = 0; i < base; i++) {
4606 cond_resched();
4607 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4608 }
4609 }
4610 /*
4611 * Clear remaining sub-pages in left-right-left-right pattern
4612 * towards the sub-page to access
4613 */
4614 for (i = 0; i < l; i++) {
4615 int left_idx = base + i;
4616 int right_idx = base + 2 * l - 1 - i;
4617
4618 cond_resched();
4619 clear_user_highpage(page + left_idx,
4620 addr + left_idx * PAGE_SIZE);
4621 cond_resched();
4622 clear_user_highpage(page + right_idx,
4623 addr + right_idx * PAGE_SIZE);
4624 }
4625}
4626
4627static void copy_user_gigantic_page(struct page *dst, struct page *src,
4628 unsigned long addr,
4629 struct vm_area_struct *vma,
4630 unsigned int pages_per_huge_page)
4631{
4632 int i;
4633 struct page *dst_base = dst;
4634 struct page *src_base = src;
4635
4636 for (i = 0; i < pages_per_huge_page; ) {
4637 cond_resched();
4638 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4639
4640 i++;
4641 dst = mem_map_next(dst, dst_base, i);
4642 src = mem_map_next(src, src_base, i);
4643 }
4644}
4645
4646void copy_user_huge_page(struct page *dst, struct page *src,
4647 unsigned long addr, struct vm_area_struct *vma,
4648 unsigned int pages_per_huge_page)
4649{
4650 int i;
4651
4652 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4653 copy_user_gigantic_page(dst, src, addr, vma,
4654 pages_per_huge_page);
4655 return;
4656 }
4657
4658 might_sleep();
4659 for (i = 0; i < pages_per_huge_page; i++) {
4660 cond_resched();
4661 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4662 }
4663}
4664
4665long copy_huge_page_from_user(struct page *dst_page,
4666 const void __user *usr_src,
4667 unsigned int pages_per_huge_page,
4668 bool allow_pagefault)
4669{
4670 void *src = (void *)usr_src;
4671 void *page_kaddr;
4672 unsigned long i, rc = 0;
4673 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4674
4675 for (i = 0; i < pages_per_huge_page; i++) {
4676 if (allow_pagefault)
4677 page_kaddr = kmap(dst_page + i);
4678 else
4679 page_kaddr = kmap_atomic(dst_page + i);
4680 rc = copy_from_user(page_kaddr,
4681 (const void __user *)(src + i * PAGE_SIZE),
4682 PAGE_SIZE);
4683 if (allow_pagefault)
4684 kunmap(dst_page + i);
4685 else
4686 kunmap_atomic(page_kaddr);
4687
4688 ret_val -= (PAGE_SIZE - rc);
4689 if (rc)
4690 break;
4691
4692 cond_resched();
4693 }
4694 return ret_val;
4695}
4696#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4697
4698#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4699
4700static struct kmem_cache *page_ptl_cachep;
4701
4702void __init ptlock_cache_init(void)
4703{
4704 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4705 SLAB_PANIC, NULL);
4706}
4707
4708bool ptlock_alloc(struct page *page)
4709{
4710 spinlock_t *ptl;
4711
4712 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4713 if (!ptl)
4714 return false;
4715 page->ptl = ptl;
4716 return true;
4717}
4718
4719void ptlock_free(struct page *page)
4720{
4721 kmem_cache_free(page_ptl_cachep, page->ptl);
4722}
4723#endif
1/*
2 * linux/mm/memory.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
10 */
11
12/*
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
15 *
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
18 * far as I could see.
19 *
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21 */
22
23/*
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
29 */
30
31/*
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
34 *
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
37 *
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39 */
40
41#include <linux/kernel_stat.h>
42#include <linux/mm.h>
43#include <linux/hugetlb.h>
44#include <linux/mman.h>
45#include <linux/swap.h>
46#include <linux/highmem.h>
47#include <linux/pagemap.h>
48#include <linux/ksm.h>
49#include <linux/rmap.h>
50#include <linux/module.h>
51#include <linux/delayacct.h>
52#include <linux/init.h>
53#include <linux/writeback.h>
54#include <linux/memcontrol.h>
55#include <linux/mmu_notifier.h>
56#include <linux/kallsyms.h>
57#include <linux/swapops.h>
58#include <linux/elf.h>
59#include <linux/gfp.h>
60
61#include <asm/io.h>
62#include <asm/pgalloc.h>
63#include <asm/uaccess.h>
64#include <asm/tlb.h>
65#include <asm/tlbflush.h>
66#include <asm/pgtable.h>
67
68#include "internal.h"
69
70#ifndef CONFIG_NEED_MULTIPLE_NODES
71/* use the per-pgdat data instead for discontigmem - mbligh */
72unsigned long max_mapnr;
73struct page *mem_map;
74
75EXPORT_SYMBOL(max_mapnr);
76EXPORT_SYMBOL(mem_map);
77#endif
78
79unsigned long num_physpages;
80/*
81 * A number of key systems in x86 including ioremap() rely on the assumption
82 * that high_memory defines the upper bound on direct map memory, then end
83 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85 * and ZONE_HIGHMEM.
86 */
87void * high_memory;
88
89EXPORT_SYMBOL(num_physpages);
90EXPORT_SYMBOL(high_memory);
91
92/*
93 * Randomize the address space (stacks, mmaps, brk, etc.).
94 *
95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96 * as ancient (libc5 based) binaries can segfault. )
97 */
98int randomize_va_space __read_mostly =
99#ifdef CONFIG_COMPAT_BRK
100 1;
101#else
102 2;
103#endif
104
105static int __init disable_randmaps(char *s)
106{
107 randomize_va_space = 0;
108 return 1;
109}
110__setup("norandmaps", disable_randmaps);
111
112unsigned long zero_pfn __read_mostly;
113unsigned long highest_memmap_pfn __read_mostly;
114
115/*
116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117 */
118static int __init init_zero_pfn(void)
119{
120 zero_pfn = page_to_pfn(ZERO_PAGE(0));
121 return 0;
122}
123core_initcall(init_zero_pfn);
124
125
126#if defined(SPLIT_RSS_COUNTING)
127
128static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
129{
130 int i;
131
132 for (i = 0; i < NR_MM_COUNTERS; i++) {
133 if (task->rss_stat.count[i]) {
134 add_mm_counter(mm, i, task->rss_stat.count[i]);
135 task->rss_stat.count[i] = 0;
136 }
137 }
138 task->rss_stat.events = 0;
139}
140
141static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142{
143 struct task_struct *task = current;
144
145 if (likely(task->mm == mm))
146 task->rss_stat.count[member] += val;
147 else
148 add_mm_counter(mm, member, val);
149}
150#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152
153/* sync counter once per 64 page faults */
154#define TASK_RSS_EVENTS_THRESH (64)
155static void check_sync_rss_stat(struct task_struct *task)
156{
157 if (unlikely(task != current))
158 return;
159 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160 __sync_task_rss_stat(task, task->mm);
161}
162
163unsigned long get_mm_counter(struct mm_struct *mm, int member)
164{
165 long val = 0;
166
167 /*
168 * Don't use task->mm here...for avoiding to use task_get_mm()..
169 * The caller must guarantee task->mm is not invalid.
170 */
171 val = atomic_long_read(&mm->rss_stat.count[member]);
172 /*
173 * counter is updated in asynchronous manner and may go to minus.
174 * But it's never be expected number for users.
175 */
176 if (val < 0)
177 return 0;
178 return (unsigned long)val;
179}
180
181void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
182{
183 __sync_task_rss_stat(task, mm);
184}
185#else /* SPLIT_RSS_COUNTING */
186
187#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
189
190static void check_sync_rss_stat(struct task_struct *task)
191{
192}
193
194#endif /* SPLIT_RSS_COUNTING */
195
196#ifdef HAVE_GENERIC_MMU_GATHER
197
198static int tlb_next_batch(struct mmu_gather *tlb)
199{
200 struct mmu_gather_batch *batch;
201
202 batch = tlb->active;
203 if (batch->next) {
204 tlb->active = batch->next;
205 return 1;
206 }
207
208 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
209 if (!batch)
210 return 0;
211
212 batch->next = NULL;
213 batch->nr = 0;
214 batch->max = MAX_GATHER_BATCH;
215
216 tlb->active->next = batch;
217 tlb->active = batch;
218
219 return 1;
220}
221
222/* tlb_gather_mmu
223 * Called to initialize an (on-stack) mmu_gather structure for page-table
224 * tear-down from @mm. The @fullmm argument is used when @mm is without
225 * users and we're going to destroy the full address space (exit/execve).
226 */
227void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
228{
229 tlb->mm = mm;
230
231 tlb->fullmm = fullmm;
232 tlb->need_flush = 0;
233 tlb->fast_mode = (num_possible_cpus() == 1);
234 tlb->local.next = NULL;
235 tlb->local.nr = 0;
236 tlb->local.max = ARRAY_SIZE(tlb->__pages);
237 tlb->active = &tlb->local;
238
239#ifdef CONFIG_HAVE_RCU_TABLE_FREE
240 tlb->batch = NULL;
241#endif
242}
243
244void tlb_flush_mmu(struct mmu_gather *tlb)
245{
246 struct mmu_gather_batch *batch;
247
248 if (!tlb->need_flush)
249 return;
250 tlb->need_flush = 0;
251 tlb_flush(tlb);
252#ifdef CONFIG_HAVE_RCU_TABLE_FREE
253 tlb_table_flush(tlb);
254#endif
255
256 if (tlb_fast_mode(tlb))
257 return;
258
259 for (batch = &tlb->local; batch; batch = batch->next) {
260 free_pages_and_swap_cache(batch->pages, batch->nr);
261 batch->nr = 0;
262 }
263 tlb->active = &tlb->local;
264}
265
266/* tlb_finish_mmu
267 * Called at the end of the shootdown operation to free up any resources
268 * that were required.
269 */
270void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
271{
272 struct mmu_gather_batch *batch, *next;
273
274 tlb_flush_mmu(tlb);
275
276 /* keep the page table cache within bounds */
277 check_pgt_cache();
278
279 for (batch = tlb->local.next; batch; batch = next) {
280 next = batch->next;
281 free_pages((unsigned long)batch, 0);
282 }
283 tlb->local.next = NULL;
284}
285
286/* __tlb_remove_page
287 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
288 * handling the additional races in SMP caused by other CPUs caching valid
289 * mappings in their TLBs. Returns the number of free page slots left.
290 * When out of page slots we must call tlb_flush_mmu().
291 */
292int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
293{
294 struct mmu_gather_batch *batch;
295
296 tlb->need_flush = 1;
297
298 if (tlb_fast_mode(tlb)) {
299 free_page_and_swap_cache(page);
300 return 1; /* avoid calling tlb_flush_mmu() */
301 }
302
303 batch = tlb->active;
304 batch->pages[batch->nr++] = page;
305 if (batch->nr == batch->max) {
306 if (!tlb_next_batch(tlb))
307 return 0;
308 batch = tlb->active;
309 }
310 VM_BUG_ON(batch->nr > batch->max);
311
312 return batch->max - batch->nr;
313}
314
315#endif /* HAVE_GENERIC_MMU_GATHER */
316
317#ifdef CONFIG_HAVE_RCU_TABLE_FREE
318
319/*
320 * See the comment near struct mmu_table_batch.
321 */
322
323static void tlb_remove_table_smp_sync(void *arg)
324{
325 /* Simply deliver the interrupt */
326}
327
328static void tlb_remove_table_one(void *table)
329{
330 /*
331 * This isn't an RCU grace period and hence the page-tables cannot be
332 * assumed to be actually RCU-freed.
333 *
334 * It is however sufficient for software page-table walkers that rely on
335 * IRQ disabling. See the comment near struct mmu_table_batch.
336 */
337 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
338 __tlb_remove_table(table);
339}
340
341static void tlb_remove_table_rcu(struct rcu_head *head)
342{
343 struct mmu_table_batch *batch;
344 int i;
345
346 batch = container_of(head, struct mmu_table_batch, rcu);
347
348 for (i = 0; i < batch->nr; i++)
349 __tlb_remove_table(batch->tables[i]);
350
351 free_page((unsigned long)batch);
352}
353
354void tlb_table_flush(struct mmu_gather *tlb)
355{
356 struct mmu_table_batch **batch = &tlb->batch;
357
358 if (*batch) {
359 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
360 *batch = NULL;
361 }
362}
363
364void tlb_remove_table(struct mmu_gather *tlb, void *table)
365{
366 struct mmu_table_batch **batch = &tlb->batch;
367
368 tlb->need_flush = 1;
369
370 /*
371 * When there's less then two users of this mm there cannot be a
372 * concurrent page-table walk.
373 */
374 if (atomic_read(&tlb->mm->mm_users) < 2) {
375 __tlb_remove_table(table);
376 return;
377 }
378
379 if (*batch == NULL) {
380 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
381 if (*batch == NULL) {
382 tlb_remove_table_one(table);
383 return;
384 }
385 (*batch)->nr = 0;
386 }
387 (*batch)->tables[(*batch)->nr++] = table;
388 if ((*batch)->nr == MAX_TABLE_BATCH)
389 tlb_table_flush(tlb);
390}
391
392#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
393
394/*
395 * If a p?d_bad entry is found while walking page tables, report
396 * the error, before resetting entry to p?d_none. Usually (but
397 * very seldom) called out from the p?d_none_or_clear_bad macros.
398 */
399
400void pgd_clear_bad(pgd_t *pgd)
401{
402 pgd_ERROR(*pgd);
403 pgd_clear(pgd);
404}
405
406void pud_clear_bad(pud_t *pud)
407{
408 pud_ERROR(*pud);
409 pud_clear(pud);
410}
411
412void pmd_clear_bad(pmd_t *pmd)
413{
414 pmd_ERROR(*pmd);
415 pmd_clear(pmd);
416}
417
418/*
419 * Note: this doesn't free the actual pages themselves. That
420 * has been handled earlier when unmapping all the memory regions.
421 */
422static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
423 unsigned long addr)
424{
425 pgtable_t token = pmd_pgtable(*pmd);
426 pmd_clear(pmd);
427 pte_free_tlb(tlb, token, addr);
428 tlb->mm->nr_ptes--;
429}
430
431static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
432 unsigned long addr, unsigned long end,
433 unsigned long floor, unsigned long ceiling)
434{
435 pmd_t *pmd;
436 unsigned long next;
437 unsigned long start;
438
439 start = addr;
440 pmd = pmd_offset(pud, addr);
441 do {
442 next = pmd_addr_end(addr, end);
443 if (pmd_none_or_clear_bad(pmd))
444 continue;
445 free_pte_range(tlb, pmd, addr);
446 } while (pmd++, addr = next, addr != end);
447
448 start &= PUD_MASK;
449 if (start < floor)
450 return;
451 if (ceiling) {
452 ceiling &= PUD_MASK;
453 if (!ceiling)
454 return;
455 }
456 if (end - 1 > ceiling - 1)
457 return;
458
459 pmd = pmd_offset(pud, start);
460 pud_clear(pud);
461 pmd_free_tlb(tlb, pmd, start);
462}
463
464static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
465 unsigned long addr, unsigned long end,
466 unsigned long floor, unsigned long ceiling)
467{
468 pud_t *pud;
469 unsigned long next;
470 unsigned long start;
471
472 start = addr;
473 pud = pud_offset(pgd, addr);
474 do {
475 next = pud_addr_end(addr, end);
476 if (pud_none_or_clear_bad(pud))
477 continue;
478 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
479 } while (pud++, addr = next, addr != end);
480
481 start &= PGDIR_MASK;
482 if (start < floor)
483 return;
484 if (ceiling) {
485 ceiling &= PGDIR_MASK;
486 if (!ceiling)
487 return;
488 }
489 if (end - 1 > ceiling - 1)
490 return;
491
492 pud = pud_offset(pgd, start);
493 pgd_clear(pgd);
494 pud_free_tlb(tlb, pud, start);
495}
496
497/*
498 * This function frees user-level page tables of a process.
499 *
500 * Must be called with pagetable lock held.
501 */
502void free_pgd_range(struct mmu_gather *tlb,
503 unsigned long addr, unsigned long end,
504 unsigned long floor, unsigned long ceiling)
505{
506 pgd_t *pgd;
507 unsigned long next;
508
509 /*
510 * The next few lines have given us lots of grief...
511 *
512 * Why are we testing PMD* at this top level? Because often
513 * there will be no work to do at all, and we'd prefer not to
514 * go all the way down to the bottom just to discover that.
515 *
516 * Why all these "- 1"s? Because 0 represents both the bottom
517 * of the address space and the top of it (using -1 for the
518 * top wouldn't help much: the masks would do the wrong thing).
519 * The rule is that addr 0 and floor 0 refer to the bottom of
520 * the address space, but end 0 and ceiling 0 refer to the top
521 * Comparisons need to use "end - 1" and "ceiling - 1" (though
522 * that end 0 case should be mythical).
523 *
524 * Wherever addr is brought up or ceiling brought down, we must
525 * be careful to reject "the opposite 0" before it confuses the
526 * subsequent tests. But what about where end is brought down
527 * by PMD_SIZE below? no, end can't go down to 0 there.
528 *
529 * Whereas we round start (addr) and ceiling down, by different
530 * masks at different levels, in order to test whether a table
531 * now has no other vmas using it, so can be freed, we don't
532 * bother to round floor or end up - the tests don't need that.
533 */
534
535 addr &= PMD_MASK;
536 if (addr < floor) {
537 addr += PMD_SIZE;
538 if (!addr)
539 return;
540 }
541 if (ceiling) {
542 ceiling &= PMD_MASK;
543 if (!ceiling)
544 return;
545 }
546 if (end - 1 > ceiling - 1)
547 end -= PMD_SIZE;
548 if (addr > end - 1)
549 return;
550
551 pgd = pgd_offset(tlb->mm, addr);
552 do {
553 next = pgd_addr_end(addr, end);
554 if (pgd_none_or_clear_bad(pgd))
555 continue;
556 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
557 } while (pgd++, addr = next, addr != end);
558}
559
560void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
561 unsigned long floor, unsigned long ceiling)
562{
563 while (vma) {
564 struct vm_area_struct *next = vma->vm_next;
565 unsigned long addr = vma->vm_start;
566
567 /*
568 * Hide vma from rmap and truncate_pagecache before freeing
569 * pgtables
570 */
571 unlink_anon_vmas(vma);
572 unlink_file_vma(vma);
573
574 if (is_vm_hugetlb_page(vma)) {
575 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
576 floor, next? next->vm_start: ceiling);
577 } else {
578 /*
579 * Optimization: gather nearby vmas into one call down
580 */
581 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
582 && !is_vm_hugetlb_page(next)) {
583 vma = next;
584 next = vma->vm_next;
585 unlink_anon_vmas(vma);
586 unlink_file_vma(vma);
587 }
588 free_pgd_range(tlb, addr, vma->vm_end,
589 floor, next? next->vm_start: ceiling);
590 }
591 vma = next;
592 }
593}
594
595int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
596 pmd_t *pmd, unsigned long address)
597{
598 pgtable_t new = pte_alloc_one(mm, address);
599 int wait_split_huge_page;
600 if (!new)
601 return -ENOMEM;
602
603 /*
604 * Ensure all pte setup (eg. pte page lock and page clearing) are
605 * visible before the pte is made visible to other CPUs by being
606 * put into page tables.
607 *
608 * The other side of the story is the pointer chasing in the page
609 * table walking code (when walking the page table without locking;
610 * ie. most of the time). Fortunately, these data accesses consist
611 * of a chain of data-dependent loads, meaning most CPUs (alpha
612 * being the notable exception) will already guarantee loads are
613 * seen in-order. See the alpha page table accessors for the
614 * smp_read_barrier_depends() barriers in page table walking code.
615 */
616 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
617
618 spin_lock(&mm->page_table_lock);
619 wait_split_huge_page = 0;
620 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
621 mm->nr_ptes++;
622 pmd_populate(mm, pmd, new);
623 new = NULL;
624 } else if (unlikely(pmd_trans_splitting(*pmd)))
625 wait_split_huge_page = 1;
626 spin_unlock(&mm->page_table_lock);
627 if (new)
628 pte_free(mm, new);
629 if (wait_split_huge_page)
630 wait_split_huge_page(vma->anon_vma, pmd);
631 return 0;
632}
633
634int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
635{
636 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
637 if (!new)
638 return -ENOMEM;
639
640 smp_wmb(); /* See comment in __pte_alloc */
641
642 spin_lock(&init_mm.page_table_lock);
643 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
644 pmd_populate_kernel(&init_mm, pmd, new);
645 new = NULL;
646 } else
647 VM_BUG_ON(pmd_trans_splitting(*pmd));
648 spin_unlock(&init_mm.page_table_lock);
649 if (new)
650 pte_free_kernel(&init_mm, new);
651 return 0;
652}
653
654static inline void init_rss_vec(int *rss)
655{
656 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
657}
658
659static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
660{
661 int i;
662
663 if (current->mm == mm)
664 sync_mm_rss(current, mm);
665 for (i = 0; i < NR_MM_COUNTERS; i++)
666 if (rss[i])
667 add_mm_counter(mm, i, rss[i]);
668}
669
670/*
671 * This function is called to print an error when a bad pte
672 * is found. For example, we might have a PFN-mapped pte in
673 * a region that doesn't allow it.
674 *
675 * The calling function must still handle the error.
676 */
677static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
678 pte_t pte, struct page *page)
679{
680 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
681 pud_t *pud = pud_offset(pgd, addr);
682 pmd_t *pmd = pmd_offset(pud, addr);
683 struct address_space *mapping;
684 pgoff_t index;
685 static unsigned long resume;
686 static unsigned long nr_shown;
687 static unsigned long nr_unshown;
688
689 /*
690 * Allow a burst of 60 reports, then keep quiet for that minute;
691 * or allow a steady drip of one report per second.
692 */
693 if (nr_shown == 60) {
694 if (time_before(jiffies, resume)) {
695 nr_unshown++;
696 return;
697 }
698 if (nr_unshown) {
699 printk(KERN_ALERT
700 "BUG: Bad page map: %lu messages suppressed\n",
701 nr_unshown);
702 nr_unshown = 0;
703 }
704 nr_shown = 0;
705 }
706 if (nr_shown++ == 0)
707 resume = jiffies + 60 * HZ;
708
709 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
710 index = linear_page_index(vma, addr);
711
712 printk(KERN_ALERT
713 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
714 current->comm,
715 (long long)pte_val(pte), (long long)pmd_val(*pmd));
716 if (page)
717 dump_page(page);
718 printk(KERN_ALERT
719 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
720 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
721 /*
722 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
723 */
724 if (vma->vm_ops)
725 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
726 (unsigned long)vma->vm_ops->fault);
727 if (vma->vm_file && vma->vm_file->f_op)
728 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
729 (unsigned long)vma->vm_file->f_op->mmap);
730 dump_stack();
731 add_taint(TAINT_BAD_PAGE);
732}
733
734static inline int is_cow_mapping(vm_flags_t flags)
735{
736 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
737}
738
739#ifndef is_zero_pfn
740static inline int is_zero_pfn(unsigned long pfn)
741{
742 return pfn == zero_pfn;
743}
744#endif
745
746#ifndef my_zero_pfn
747static inline unsigned long my_zero_pfn(unsigned long addr)
748{
749 return zero_pfn;
750}
751#endif
752
753/*
754 * vm_normal_page -- This function gets the "struct page" associated with a pte.
755 *
756 * "Special" mappings do not wish to be associated with a "struct page" (either
757 * it doesn't exist, or it exists but they don't want to touch it). In this
758 * case, NULL is returned here. "Normal" mappings do have a struct page.
759 *
760 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
761 * pte bit, in which case this function is trivial. Secondly, an architecture
762 * may not have a spare pte bit, which requires a more complicated scheme,
763 * described below.
764 *
765 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
766 * special mapping (even if there are underlying and valid "struct pages").
767 * COWed pages of a VM_PFNMAP are always normal.
768 *
769 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
770 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
771 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
772 * mapping will always honor the rule
773 *
774 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
775 *
776 * And for normal mappings this is false.
777 *
778 * This restricts such mappings to be a linear translation from virtual address
779 * to pfn. To get around this restriction, we allow arbitrary mappings so long
780 * as the vma is not a COW mapping; in that case, we know that all ptes are
781 * special (because none can have been COWed).
782 *
783 *
784 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
785 *
786 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
787 * page" backing, however the difference is that _all_ pages with a struct
788 * page (that is, those where pfn_valid is true) are refcounted and considered
789 * normal pages by the VM. The disadvantage is that pages are refcounted
790 * (which can be slower and simply not an option for some PFNMAP users). The
791 * advantage is that we don't have to follow the strict linearity rule of
792 * PFNMAP mappings in order to support COWable mappings.
793 *
794 */
795#ifdef __HAVE_ARCH_PTE_SPECIAL
796# define HAVE_PTE_SPECIAL 1
797#else
798# define HAVE_PTE_SPECIAL 0
799#endif
800struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
801 pte_t pte)
802{
803 unsigned long pfn = pte_pfn(pte);
804
805 if (HAVE_PTE_SPECIAL) {
806 if (likely(!pte_special(pte)))
807 goto check_pfn;
808 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
809 return NULL;
810 if (!is_zero_pfn(pfn))
811 print_bad_pte(vma, addr, pte, NULL);
812 return NULL;
813 }
814
815 /* !HAVE_PTE_SPECIAL case follows: */
816
817 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
818 if (vma->vm_flags & VM_MIXEDMAP) {
819 if (!pfn_valid(pfn))
820 return NULL;
821 goto out;
822 } else {
823 unsigned long off;
824 off = (addr - vma->vm_start) >> PAGE_SHIFT;
825 if (pfn == vma->vm_pgoff + off)
826 return NULL;
827 if (!is_cow_mapping(vma->vm_flags))
828 return NULL;
829 }
830 }
831
832 if (is_zero_pfn(pfn))
833 return NULL;
834check_pfn:
835 if (unlikely(pfn > highest_memmap_pfn)) {
836 print_bad_pte(vma, addr, pte, NULL);
837 return NULL;
838 }
839
840 /*
841 * NOTE! We still have PageReserved() pages in the page tables.
842 * eg. VDSO mappings can cause them to exist.
843 */
844out:
845 return pfn_to_page(pfn);
846}
847
848/*
849 * copy one vm_area from one task to the other. Assumes the page tables
850 * already present in the new task to be cleared in the whole range
851 * covered by this vma.
852 */
853
854static inline unsigned long
855copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
856 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
857 unsigned long addr, int *rss)
858{
859 unsigned long vm_flags = vma->vm_flags;
860 pte_t pte = *src_pte;
861 struct page *page;
862
863 /* pte contains position in swap or file, so copy. */
864 if (unlikely(!pte_present(pte))) {
865 if (!pte_file(pte)) {
866 swp_entry_t entry = pte_to_swp_entry(pte);
867
868 if (swap_duplicate(entry) < 0)
869 return entry.val;
870
871 /* make sure dst_mm is on swapoff's mmlist. */
872 if (unlikely(list_empty(&dst_mm->mmlist))) {
873 spin_lock(&mmlist_lock);
874 if (list_empty(&dst_mm->mmlist))
875 list_add(&dst_mm->mmlist,
876 &src_mm->mmlist);
877 spin_unlock(&mmlist_lock);
878 }
879 if (likely(!non_swap_entry(entry)))
880 rss[MM_SWAPENTS]++;
881 else if (is_write_migration_entry(entry) &&
882 is_cow_mapping(vm_flags)) {
883 /*
884 * COW mappings require pages in both parent
885 * and child to be set to read.
886 */
887 make_migration_entry_read(&entry);
888 pte = swp_entry_to_pte(entry);
889 set_pte_at(src_mm, addr, src_pte, pte);
890 }
891 }
892 goto out_set_pte;
893 }
894
895 /*
896 * If it's a COW mapping, write protect it both
897 * in the parent and the child
898 */
899 if (is_cow_mapping(vm_flags)) {
900 ptep_set_wrprotect(src_mm, addr, src_pte);
901 pte = pte_wrprotect(pte);
902 }
903
904 /*
905 * If it's a shared mapping, mark it clean in
906 * the child
907 */
908 if (vm_flags & VM_SHARED)
909 pte = pte_mkclean(pte);
910 pte = pte_mkold(pte);
911
912 page = vm_normal_page(vma, addr, pte);
913 if (page) {
914 get_page(page);
915 page_dup_rmap(page);
916 if (PageAnon(page))
917 rss[MM_ANONPAGES]++;
918 else
919 rss[MM_FILEPAGES]++;
920 }
921
922out_set_pte:
923 set_pte_at(dst_mm, addr, dst_pte, pte);
924 return 0;
925}
926
927int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
928 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
929 unsigned long addr, unsigned long end)
930{
931 pte_t *orig_src_pte, *orig_dst_pte;
932 pte_t *src_pte, *dst_pte;
933 spinlock_t *src_ptl, *dst_ptl;
934 int progress = 0;
935 int rss[NR_MM_COUNTERS];
936 swp_entry_t entry = (swp_entry_t){0};
937
938again:
939 init_rss_vec(rss);
940
941 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
942 if (!dst_pte)
943 return -ENOMEM;
944 src_pte = pte_offset_map(src_pmd, addr);
945 src_ptl = pte_lockptr(src_mm, src_pmd);
946 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
947 orig_src_pte = src_pte;
948 orig_dst_pte = dst_pte;
949 arch_enter_lazy_mmu_mode();
950
951 do {
952 /*
953 * We are holding two locks at this point - either of them
954 * could generate latencies in another task on another CPU.
955 */
956 if (progress >= 32) {
957 progress = 0;
958 if (need_resched() ||
959 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
960 break;
961 }
962 if (pte_none(*src_pte)) {
963 progress++;
964 continue;
965 }
966 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
967 vma, addr, rss);
968 if (entry.val)
969 break;
970 progress += 8;
971 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
972
973 arch_leave_lazy_mmu_mode();
974 spin_unlock(src_ptl);
975 pte_unmap(orig_src_pte);
976 add_mm_rss_vec(dst_mm, rss);
977 pte_unmap_unlock(orig_dst_pte, dst_ptl);
978 cond_resched();
979
980 if (entry.val) {
981 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
982 return -ENOMEM;
983 progress = 0;
984 }
985 if (addr != end)
986 goto again;
987 return 0;
988}
989
990static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
991 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
992 unsigned long addr, unsigned long end)
993{
994 pmd_t *src_pmd, *dst_pmd;
995 unsigned long next;
996
997 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
998 if (!dst_pmd)
999 return -ENOMEM;
1000 src_pmd = pmd_offset(src_pud, addr);
1001 do {
1002 next = pmd_addr_end(addr, end);
1003 if (pmd_trans_huge(*src_pmd)) {
1004 int err;
1005 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1006 err = copy_huge_pmd(dst_mm, src_mm,
1007 dst_pmd, src_pmd, addr, vma);
1008 if (err == -ENOMEM)
1009 return -ENOMEM;
1010 if (!err)
1011 continue;
1012 /* fall through */
1013 }
1014 if (pmd_none_or_clear_bad(src_pmd))
1015 continue;
1016 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1017 vma, addr, next))
1018 return -ENOMEM;
1019 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1020 return 0;
1021}
1022
1023static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1024 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1025 unsigned long addr, unsigned long end)
1026{
1027 pud_t *src_pud, *dst_pud;
1028 unsigned long next;
1029
1030 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1031 if (!dst_pud)
1032 return -ENOMEM;
1033 src_pud = pud_offset(src_pgd, addr);
1034 do {
1035 next = pud_addr_end(addr, end);
1036 if (pud_none_or_clear_bad(src_pud))
1037 continue;
1038 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1039 vma, addr, next))
1040 return -ENOMEM;
1041 } while (dst_pud++, src_pud++, addr = next, addr != end);
1042 return 0;
1043}
1044
1045int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046 struct vm_area_struct *vma)
1047{
1048 pgd_t *src_pgd, *dst_pgd;
1049 unsigned long next;
1050 unsigned long addr = vma->vm_start;
1051 unsigned long end = vma->vm_end;
1052 int ret;
1053
1054 /*
1055 * Don't copy ptes where a page fault will fill them correctly.
1056 * Fork becomes much lighter when there are big shared or private
1057 * readonly mappings. The tradeoff is that copy_page_range is more
1058 * efficient than faulting.
1059 */
1060 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1061 if (!vma->anon_vma)
1062 return 0;
1063 }
1064
1065 if (is_vm_hugetlb_page(vma))
1066 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1067
1068 if (unlikely(is_pfn_mapping(vma))) {
1069 /*
1070 * We do not free on error cases below as remove_vma
1071 * gets called on error from higher level routine
1072 */
1073 ret = track_pfn_vma_copy(vma);
1074 if (ret)
1075 return ret;
1076 }
1077
1078 /*
1079 * We need to invalidate the secondary MMU mappings only when
1080 * there could be a permission downgrade on the ptes of the
1081 * parent mm. And a permission downgrade will only happen if
1082 * is_cow_mapping() returns true.
1083 */
1084 if (is_cow_mapping(vma->vm_flags))
1085 mmu_notifier_invalidate_range_start(src_mm, addr, end);
1086
1087 ret = 0;
1088 dst_pgd = pgd_offset(dst_mm, addr);
1089 src_pgd = pgd_offset(src_mm, addr);
1090 do {
1091 next = pgd_addr_end(addr, end);
1092 if (pgd_none_or_clear_bad(src_pgd))
1093 continue;
1094 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1095 vma, addr, next))) {
1096 ret = -ENOMEM;
1097 break;
1098 }
1099 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1100
1101 if (is_cow_mapping(vma->vm_flags))
1102 mmu_notifier_invalidate_range_end(src_mm,
1103 vma->vm_start, end);
1104 return ret;
1105}
1106
1107static unsigned long zap_pte_range(struct mmu_gather *tlb,
1108 struct vm_area_struct *vma, pmd_t *pmd,
1109 unsigned long addr, unsigned long end,
1110 struct zap_details *details)
1111{
1112 struct mm_struct *mm = tlb->mm;
1113 int force_flush = 0;
1114 int rss[NR_MM_COUNTERS];
1115 spinlock_t *ptl;
1116 pte_t *start_pte;
1117 pte_t *pte;
1118
1119again:
1120 init_rss_vec(rss);
1121 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1122 pte = start_pte;
1123 arch_enter_lazy_mmu_mode();
1124 do {
1125 pte_t ptent = *pte;
1126 if (pte_none(ptent)) {
1127 continue;
1128 }
1129
1130 if (pte_present(ptent)) {
1131 struct page *page;
1132
1133 page = vm_normal_page(vma, addr, ptent);
1134 if (unlikely(details) && page) {
1135 /*
1136 * unmap_shared_mapping_pages() wants to
1137 * invalidate cache without truncating:
1138 * unmap shared but keep private pages.
1139 */
1140 if (details->check_mapping &&
1141 details->check_mapping != page->mapping)
1142 continue;
1143 /*
1144 * Each page->index must be checked when
1145 * invalidating or truncating nonlinear.
1146 */
1147 if (details->nonlinear_vma &&
1148 (page->index < details->first_index ||
1149 page->index > details->last_index))
1150 continue;
1151 }
1152 ptent = ptep_get_and_clear_full(mm, addr, pte,
1153 tlb->fullmm);
1154 tlb_remove_tlb_entry(tlb, pte, addr);
1155 if (unlikely(!page))
1156 continue;
1157 if (unlikely(details) && details->nonlinear_vma
1158 && linear_page_index(details->nonlinear_vma,
1159 addr) != page->index)
1160 set_pte_at(mm, addr, pte,
1161 pgoff_to_pte(page->index));
1162 if (PageAnon(page))
1163 rss[MM_ANONPAGES]--;
1164 else {
1165 if (pte_dirty(ptent))
1166 set_page_dirty(page);
1167 if (pte_young(ptent) &&
1168 likely(!VM_SequentialReadHint(vma)))
1169 mark_page_accessed(page);
1170 rss[MM_FILEPAGES]--;
1171 }
1172 page_remove_rmap(page);
1173 if (unlikely(page_mapcount(page) < 0))
1174 print_bad_pte(vma, addr, ptent, page);
1175 force_flush = !__tlb_remove_page(tlb, page);
1176 if (force_flush)
1177 break;
1178 continue;
1179 }
1180 /*
1181 * If details->check_mapping, we leave swap entries;
1182 * if details->nonlinear_vma, we leave file entries.
1183 */
1184 if (unlikely(details))
1185 continue;
1186 if (pte_file(ptent)) {
1187 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1188 print_bad_pte(vma, addr, ptent, NULL);
1189 } else {
1190 swp_entry_t entry = pte_to_swp_entry(ptent);
1191
1192 if (!non_swap_entry(entry))
1193 rss[MM_SWAPENTS]--;
1194 if (unlikely(!free_swap_and_cache(entry)))
1195 print_bad_pte(vma, addr, ptent, NULL);
1196 }
1197 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198 } while (pte++, addr += PAGE_SIZE, addr != end);
1199
1200 add_mm_rss_vec(mm, rss);
1201 arch_leave_lazy_mmu_mode();
1202 pte_unmap_unlock(start_pte, ptl);
1203
1204 /*
1205 * mmu_gather ran out of room to batch pages, we break out of
1206 * the PTE lock to avoid doing the potential expensive TLB invalidate
1207 * and page-free while holding it.
1208 */
1209 if (force_flush) {
1210 force_flush = 0;
1211 tlb_flush_mmu(tlb);
1212 if (addr != end)
1213 goto again;
1214 }
1215
1216 return addr;
1217}
1218
1219static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1220 struct vm_area_struct *vma, pud_t *pud,
1221 unsigned long addr, unsigned long end,
1222 struct zap_details *details)
1223{
1224 pmd_t *pmd;
1225 unsigned long next;
1226
1227 pmd = pmd_offset(pud, addr);
1228 do {
1229 next = pmd_addr_end(addr, end);
1230 if (pmd_trans_huge(*pmd)) {
1231 if (next-addr != HPAGE_PMD_SIZE) {
1232 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1233 split_huge_page_pmd(vma->vm_mm, pmd);
1234 } else if (zap_huge_pmd(tlb, vma, pmd))
1235 continue;
1236 /* fall through */
1237 }
1238 if (pmd_none_or_clear_bad(pmd))
1239 continue;
1240 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1241 cond_resched();
1242 } while (pmd++, addr = next, addr != end);
1243
1244 return addr;
1245}
1246
1247static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1248 struct vm_area_struct *vma, pgd_t *pgd,
1249 unsigned long addr, unsigned long end,
1250 struct zap_details *details)
1251{
1252 pud_t *pud;
1253 unsigned long next;
1254
1255 pud = pud_offset(pgd, addr);
1256 do {
1257 next = pud_addr_end(addr, end);
1258 if (pud_none_or_clear_bad(pud))
1259 continue;
1260 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1261 } while (pud++, addr = next, addr != end);
1262
1263 return addr;
1264}
1265
1266static unsigned long unmap_page_range(struct mmu_gather *tlb,
1267 struct vm_area_struct *vma,
1268 unsigned long addr, unsigned long end,
1269 struct zap_details *details)
1270{
1271 pgd_t *pgd;
1272 unsigned long next;
1273
1274 if (details && !details->check_mapping && !details->nonlinear_vma)
1275 details = NULL;
1276
1277 BUG_ON(addr >= end);
1278 mem_cgroup_uncharge_start();
1279 tlb_start_vma(tlb, vma);
1280 pgd = pgd_offset(vma->vm_mm, addr);
1281 do {
1282 next = pgd_addr_end(addr, end);
1283 if (pgd_none_or_clear_bad(pgd))
1284 continue;
1285 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1286 } while (pgd++, addr = next, addr != end);
1287 tlb_end_vma(tlb, vma);
1288 mem_cgroup_uncharge_end();
1289
1290 return addr;
1291}
1292
1293/**
1294 * unmap_vmas - unmap a range of memory covered by a list of vma's
1295 * @tlb: address of the caller's struct mmu_gather
1296 * @vma: the starting vma
1297 * @start_addr: virtual address at which to start unmapping
1298 * @end_addr: virtual address at which to end unmapping
1299 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1300 * @details: details of nonlinear truncation or shared cache invalidation
1301 *
1302 * Returns the end address of the unmapping (restart addr if interrupted).
1303 *
1304 * Unmap all pages in the vma list.
1305 *
1306 * Only addresses between `start' and `end' will be unmapped.
1307 *
1308 * The VMA list must be sorted in ascending virtual address order.
1309 *
1310 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1311 * range after unmap_vmas() returns. So the only responsibility here is to
1312 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1313 * drops the lock and schedules.
1314 */
1315unsigned long unmap_vmas(struct mmu_gather *tlb,
1316 struct vm_area_struct *vma, unsigned long start_addr,
1317 unsigned long end_addr, unsigned long *nr_accounted,
1318 struct zap_details *details)
1319{
1320 unsigned long start = start_addr;
1321 struct mm_struct *mm = vma->vm_mm;
1322
1323 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1324 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1325 unsigned long end;
1326
1327 start = max(vma->vm_start, start_addr);
1328 if (start >= vma->vm_end)
1329 continue;
1330 end = min(vma->vm_end, end_addr);
1331 if (end <= vma->vm_start)
1332 continue;
1333
1334 if (vma->vm_flags & VM_ACCOUNT)
1335 *nr_accounted += (end - start) >> PAGE_SHIFT;
1336
1337 if (unlikely(is_pfn_mapping(vma)))
1338 untrack_pfn_vma(vma, 0, 0);
1339
1340 while (start != end) {
1341 if (unlikely(is_vm_hugetlb_page(vma))) {
1342 /*
1343 * It is undesirable to test vma->vm_file as it
1344 * should be non-null for valid hugetlb area.
1345 * However, vm_file will be NULL in the error
1346 * cleanup path of do_mmap_pgoff. When
1347 * hugetlbfs ->mmap method fails,
1348 * do_mmap_pgoff() nullifies vma->vm_file
1349 * before calling this function to clean up.
1350 * Since no pte has actually been setup, it is
1351 * safe to do nothing in this case.
1352 */
1353 if (vma->vm_file)
1354 unmap_hugepage_range(vma, start, end, NULL);
1355
1356 start = end;
1357 } else
1358 start = unmap_page_range(tlb, vma, start, end, details);
1359 }
1360 }
1361
1362 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1363 return start; /* which is now the end (or restart) address */
1364}
1365
1366/**
1367 * zap_page_range - remove user pages in a given range
1368 * @vma: vm_area_struct holding the applicable pages
1369 * @address: starting address of pages to zap
1370 * @size: number of bytes to zap
1371 * @details: details of nonlinear truncation or shared cache invalidation
1372 */
1373unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1374 unsigned long size, struct zap_details *details)
1375{
1376 struct mm_struct *mm = vma->vm_mm;
1377 struct mmu_gather tlb;
1378 unsigned long end = address + size;
1379 unsigned long nr_accounted = 0;
1380
1381 lru_add_drain();
1382 tlb_gather_mmu(&tlb, mm, 0);
1383 update_hiwater_rss(mm);
1384 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1385 tlb_finish_mmu(&tlb, address, end);
1386 return end;
1387}
1388
1389/**
1390 * zap_vma_ptes - remove ptes mapping the vma
1391 * @vma: vm_area_struct holding ptes to be zapped
1392 * @address: starting address of pages to zap
1393 * @size: number of bytes to zap
1394 *
1395 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1396 *
1397 * The entire address range must be fully contained within the vma.
1398 *
1399 * Returns 0 if successful.
1400 */
1401int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1402 unsigned long size)
1403{
1404 if (address < vma->vm_start || address + size > vma->vm_end ||
1405 !(vma->vm_flags & VM_PFNMAP))
1406 return -1;
1407 zap_page_range(vma, address, size, NULL);
1408 return 0;
1409}
1410EXPORT_SYMBOL_GPL(zap_vma_ptes);
1411
1412/**
1413 * follow_page - look up a page descriptor from a user-virtual address
1414 * @vma: vm_area_struct mapping @address
1415 * @address: virtual address to look up
1416 * @flags: flags modifying lookup behaviour
1417 *
1418 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1419 *
1420 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1421 * an error pointer if there is a mapping to something not represented
1422 * by a page descriptor (see also vm_normal_page()).
1423 */
1424struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1425 unsigned int flags)
1426{
1427 pgd_t *pgd;
1428 pud_t *pud;
1429 pmd_t *pmd;
1430 pte_t *ptep, pte;
1431 spinlock_t *ptl;
1432 struct page *page;
1433 struct mm_struct *mm = vma->vm_mm;
1434
1435 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1436 if (!IS_ERR(page)) {
1437 BUG_ON(flags & FOLL_GET);
1438 goto out;
1439 }
1440
1441 page = NULL;
1442 pgd = pgd_offset(mm, address);
1443 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1444 goto no_page_table;
1445
1446 pud = pud_offset(pgd, address);
1447 if (pud_none(*pud))
1448 goto no_page_table;
1449 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1450 BUG_ON(flags & FOLL_GET);
1451 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1452 goto out;
1453 }
1454 if (unlikely(pud_bad(*pud)))
1455 goto no_page_table;
1456
1457 pmd = pmd_offset(pud, address);
1458 if (pmd_none(*pmd))
1459 goto no_page_table;
1460 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1461 BUG_ON(flags & FOLL_GET);
1462 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1463 goto out;
1464 }
1465 if (pmd_trans_huge(*pmd)) {
1466 if (flags & FOLL_SPLIT) {
1467 split_huge_page_pmd(mm, pmd);
1468 goto split_fallthrough;
1469 }
1470 spin_lock(&mm->page_table_lock);
1471 if (likely(pmd_trans_huge(*pmd))) {
1472 if (unlikely(pmd_trans_splitting(*pmd))) {
1473 spin_unlock(&mm->page_table_lock);
1474 wait_split_huge_page(vma->anon_vma, pmd);
1475 } else {
1476 page = follow_trans_huge_pmd(mm, address,
1477 pmd, flags);
1478 spin_unlock(&mm->page_table_lock);
1479 goto out;
1480 }
1481 } else
1482 spin_unlock(&mm->page_table_lock);
1483 /* fall through */
1484 }
1485split_fallthrough:
1486 if (unlikely(pmd_bad(*pmd)))
1487 goto no_page_table;
1488
1489 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1490
1491 pte = *ptep;
1492 if (!pte_present(pte))
1493 goto no_page;
1494 if ((flags & FOLL_WRITE) && !pte_write(pte))
1495 goto unlock;
1496
1497 page = vm_normal_page(vma, address, pte);
1498 if (unlikely(!page)) {
1499 if ((flags & FOLL_DUMP) ||
1500 !is_zero_pfn(pte_pfn(pte)))
1501 goto bad_page;
1502 page = pte_page(pte);
1503 }
1504
1505 if (flags & FOLL_GET)
1506 get_page(page);
1507 if (flags & FOLL_TOUCH) {
1508 if ((flags & FOLL_WRITE) &&
1509 !pte_dirty(pte) && !PageDirty(page))
1510 set_page_dirty(page);
1511 /*
1512 * pte_mkyoung() would be more correct here, but atomic care
1513 * is needed to avoid losing the dirty bit: it is easier to use
1514 * mark_page_accessed().
1515 */
1516 mark_page_accessed(page);
1517 }
1518 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1519 /*
1520 * The preliminary mapping check is mainly to avoid the
1521 * pointless overhead of lock_page on the ZERO_PAGE
1522 * which might bounce very badly if there is contention.
1523 *
1524 * If the page is already locked, we don't need to
1525 * handle it now - vmscan will handle it later if and
1526 * when it attempts to reclaim the page.
1527 */
1528 if (page->mapping && trylock_page(page)) {
1529 lru_add_drain(); /* push cached pages to LRU */
1530 /*
1531 * Because we lock page here and migration is
1532 * blocked by the pte's page reference, we need
1533 * only check for file-cache page truncation.
1534 */
1535 if (page->mapping)
1536 mlock_vma_page(page);
1537 unlock_page(page);
1538 }
1539 }
1540unlock:
1541 pte_unmap_unlock(ptep, ptl);
1542out:
1543 return page;
1544
1545bad_page:
1546 pte_unmap_unlock(ptep, ptl);
1547 return ERR_PTR(-EFAULT);
1548
1549no_page:
1550 pte_unmap_unlock(ptep, ptl);
1551 if (!pte_none(pte))
1552 return page;
1553
1554no_page_table:
1555 /*
1556 * When core dumping an enormous anonymous area that nobody
1557 * has touched so far, we don't want to allocate unnecessary pages or
1558 * page tables. Return error instead of NULL to skip handle_mm_fault,
1559 * then get_dump_page() will return NULL to leave a hole in the dump.
1560 * But we can only make this optimization where a hole would surely
1561 * be zero-filled if handle_mm_fault() actually did handle it.
1562 */
1563 if ((flags & FOLL_DUMP) &&
1564 (!vma->vm_ops || !vma->vm_ops->fault))
1565 return ERR_PTR(-EFAULT);
1566 return page;
1567}
1568
1569static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1570{
1571 return stack_guard_page_start(vma, addr) ||
1572 stack_guard_page_end(vma, addr+PAGE_SIZE);
1573}
1574
1575/**
1576 * __get_user_pages() - pin user pages in memory
1577 * @tsk: task_struct of target task
1578 * @mm: mm_struct of target mm
1579 * @start: starting user address
1580 * @nr_pages: number of pages from start to pin
1581 * @gup_flags: flags modifying pin behaviour
1582 * @pages: array that receives pointers to the pages pinned.
1583 * Should be at least nr_pages long. Or NULL, if caller
1584 * only intends to ensure the pages are faulted in.
1585 * @vmas: array of pointers to vmas corresponding to each page.
1586 * Or NULL if the caller does not require them.
1587 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1588 *
1589 * Returns number of pages pinned. This may be fewer than the number
1590 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1591 * were pinned, returns -errno. Each page returned must be released
1592 * with a put_page() call when it is finished with. vmas will only
1593 * remain valid while mmap_sem is held.
1594 *
1595 * Must be called with mmap_sem held for read or write.
1596 *
1597 * __get_user_pages walks a process's page tables and takes a reference to
1598 * each struct page that each user address corresponds to at a given
1599 * instant. That is, it takes the page that would be accessed if a user
1600 * thread accesses the given user virtual address at that instant.
1601 *
1602 * This does not guarantee that the page exists in the user mappings when
1603 * __get_user_pages returns, and there may even be a completely different
1604 * page there in some cases (eg. if mmapped pagecache has been invalidated
1605 * and subsequently re faulted). However it does guarantee that the page
1606 * won't be freed completely. And mostly callers simply care that the page
1607 * contains data that was valid *at some point in time*. Typically, an IO
1608 * or similar operation cannot guarantee anything stronger anyway because
1609 * locks can't be held over the syscall boundary.
1610 *
1611 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1612 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1613 * appropriate) must be called after the page is finished with, and
1614 * before put_page is called.
1615 *
1616 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1617 * or mmap_sem contention, and if waiting is needed to pin all pages,
1618 * *@nonblocking will be set to 0.
1619 *
1620 * In most cases, get_user_pages or get_user_pages_fast should be used
1621 * instead of __get_user_pages. __get_user_pages should be used only if
1622 * you need some special @gup_flags.
1623 */
1624int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1625 unsigned long start, int nr_pages, unsigned int gup_flags,
1626 struct page **pages, struct vm_area_struct **vmas,
1627 int *nonblocking)
1628{
1629 int i;
1630 unsigned long vm_flags;
1631
1632 if (nr_pages <= 0)
1633 return 0;
1634
1635 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1636
1637 /*
1638 * Require read or write permissions.
1639 * If FOLL_FORCE is set, we only require the "MAY" flags.
1640 */
1641 vm_flags = (gup_flags & FOLL_WRITE) ?
1642 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1643 vm_flags &= (gup_flags & FOLL_FORCE) ?
1644 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1645 i = 0;
1646
1647 do {
1648 struct vm_area_struct *vma;
1649
1650 vma = find_extend_vma(mm, start);
1651 if (!vma && in_gate_area(mm, start)) {
1652 unsigned long pg = start & PAGE_MASK;
1653 pgd_t *pgd;
1654 pud_t *pud;
1655 pmd_t *pmd;
1656 pte_t *pte;
1657
1658 /* user gate pages are read-only */
1659 if (gup_flags & FOLL_WRITE)
1660 return i ? : -EFAULT;
1661 if (pg > TASK_SIZE)
1662 pgd = pgd_offset_k(pg);
1663 else
1664 pgd = pgd_offset_gate(mm, pg);
1665 BUG_ON(pgd_none(*pgd));
1666 pud = pud_offset(pgd, pg);
1667 BUG_ON(pud_none(*pud));
1668 pmd = pmd_offset(pud, pg);
1669 if (pmd_none(*pmd))
1670 return i ? : -EFAULT;
1671 VM_BUG_ON(pmd_trans_huge(*pmd));
1672 pte = pte_offset_map(pmd, pg);
1673 if (pte_none(*pte)) {
1674 pte_unmap(pte);
1675 return i ? : -EFAULT;
1676 }
1677 vma = get_gate_vma(mm);
1678 if (pages) {
1679 struct page *page;
1680
1681 page = vm_normal_page(vma, start, *pte);
1682 if (!page) {
1683 if (!(gup_flags & FOLL_DUMP) &&
1684 is_zero_pfn(pte_pfn(*pte)))
1685 page = pte_page(*pte);
1686 else {
1687 pte_unmap(pte);
1688 return i ? : -EFAULT;
1689 }
1690 }
1691 pages[i] = page;
1692 get_page(page);
1693 }
1694 pte_unmap(pte);
1695 goto next_page;
1696 }
1697
1698 if (!vma ||
1699 (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1700 !(vm_flags & vma->vm_flags))
1701 return i ? : -EFAULT;
1702
1703 if (is_vm_hugetlb_page(vma)) {
1704 i = follow_hugetlb_page(mm, vma, pages, vmas,
1705 &start, &nr_pages, i, gup_flags);
1706 continue;
1707 }
1708
1709 do {
1710 struct page *page;
1711 unsigned int foll_flags = gup_flags;
1712
1713 /*
1714 * If we have a pending SIGKILL, don't keep faulting
1715 * pages and potentially allocating memory.
1716 */
1717 if (unlikely(fatal_signal_pending(current)))
1718 return i ? i : -ERESTARTSYS;
1719
1720 cond_resched();
1721 while (!(page = follow_page(vma, start, foll_flags))) {
1722 int ret;
1723 unsigned int fault_flags = 0;
1724
1725 /* For mlock, just skip the stack guard page. */
1726 if (foll_flags & FOLL_MLOCK) {
1727 if (stack_guard_page(vma, start))
1728 goto next_page;
1729 }
1730 if (foll_flags & FOLL_WRITE)
1731 fault_flags |= FAULT_FLAG_WRITE;
1732 if (nonblocking)
1733 fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1734 if (foll_flags & FOLL_NOWAIT)
1735 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1736
1737 ret = handle_mm_fault(mm, vma, start,
1738 fault_flags);
1739
1740 if (ret & VM_FAULT_ERROR) {
1741 if (ret & VM_FAULT_OOM)
1742 return i ? i : -ENOMEM;
1743 if (ret & (VM_FAULT_HWPOISON |
1744 VM_FAULT_HWPOISON_LARGE)) {
1745 if (i)
1746 return i;
1747 else if (gup_flags & FOLL_HWPOISON)
1748 return -EHWPOISON;
1749 else
1750 return -EFAULT;
1751 }
1752 if (ret & VM_FAULT_SIGBUS)
1753 return i ? i : -EFAULT;
1754 BUG();
1755 }
1756
1757 if (tsk) {
1758 if (ret & VM_FAULT_MAJOR)
1759 tsk->maj_flt++;
1760 else
1761 tsk->min_flt++;
1762 }
1763
1764 if (ret & VM_FAULT_RETRY) {
1765 if (nonblocking)
1766 *nonblocking = 0;
1767 return i;
1768 }
1769
1770 /*
1771 * The VM_FAULT_WRITE bit tells us that
1772 * do_wp_page has broken COW when necessary,
1773 * even if maybe_mkwrite decided not to set
1774 * pte_write. We can thus safely do subsequent
1775 * page lookups as if they were reads. But only
1776 * do so when looping for pte_write is futile:
1777 * in some cases userspace may also be wanting
1778 * to write to the gotten user page, which a
1779 * read fault here might prevent (a readonly
1780 * page might get reCOWed by userspace write).
1781 */
1782 if ((ret & VM_FAULT_WRITE) &&
1783 !(vma->vm_flags & VM_WRITE))
1784 foll_flags &= ~FOLL_WRITE;
1785
1786 cond_resched();
1787 }
1788 if (IS_ERR(page))
1789 return i ? i : PTR_ERR(page);
1790 if (pages) {
1791 pages[i] = page;
1792
1793 flush_anon_page(vma, page, start);
1794 flush_dcache_page(page);
1795 }
1796next_page:
1797 if (vmas)
1798 vmas[i] = vma;
1799 i++;
1800 start += PAGE_SIZE;
1801 nr_pages--;
1802 } while (nr_pages && start < vma->vm_end);
1803 } while (nr_pages);
1804 return i;
1805}
1806EXPORT_SYMBOL(__get_user_pages);
1807
1808/*
1809 * fixup_user_fault() - manually resolve a user page fault
1810 * @tsk: the task_struct to use for page fault accounting, or
1811 * NULL if faults are not to be recorded.
1812 * @mm: mm_struct of target mm
1813 * @address: user address
1814 * @fault_flags:flags to pass down to handle_mm_fault()
1815 *
1816 * This is meant to be called in the specific scenario where for locking reasons
1817 * we try to access user memory in atomic context (within a pagefault_disable()
1818 * section), this returns -EFAULT, and we want to resolve the user fault before
1819 * trying again.
1820 *
1821 * Typically this is meant to be used by the futex code.
1822 *
1823 * The main difference with get_user_pages() is that this function will
1824 * unconditionally call handle_mm_fault() which will in turn perform all the
1825 * necessary SW fixup of the dirty and young bits in the PTE, while
1826 * handle_mm_fault() only guarantees to update these in the struct page.
1827 *
1828 * This is important for some architectures where those bits also gate the
1829 * access permission to the page because they are maintained in software. On
1830 * such architectures, gup() will not be enough to make a subsequent access
1831 * succeed.
1832 *
1833 * This should be called with the mm_sem held for read.
1834 */
1835int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1836 unsigned long address, unsigned int fault_flags)
1837{
1838 struct vm_area_struct *vma;
1839 int ret;
1840
1841 vma = find_extend_vma(mm, address);
1842 if (!vma || address < vma->vm_start)
1843 return -EFAULT;
1844
1845 ret = handle_mm_fault(mm, vma, address, fault_flags);
1846 if (ret & VM_FAULT_ERROR) {
1847 if (ret & VM_FAULT_OOM)
1848 return -ENOMEM;
1849 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1850 return -EHWPOISON;
1851 if (ret & VM_FAULT_SIGBUS)
1852 return -EFAULT;
1853 BUG();
1854 }
1855 if (tsk) {
1856 if (ret & VM_FAULT_MAJOR)
1857 tsk->maj_flt++;
1858 else
1859 tsk->min_flt++;
1860 }
1861 return 0;
1862}
1863
1864/*
1865 * get_user_pages() - pin user pages in memory
1866 * @tsk: the task_struct to use for page fault accounting, or
1867 * NULL if faults are not to be recorded.
1868 * @mm: mm_struct of target mm
1869 * @start: starting user address
1870 * @nr_pages: number of pages from start to pin
1871 * @write: whether pages will be written to by the caller
1872 * @force: whether to force write access even if user mapping is
1873 * readonly. This will result in the page being COWed even
1874 * in MAP_SHARED mappings. You do not want this.
1875 * @pages: array that receives pointers to the pages pinned.
1876 * Should be at least nr_pages long. Or NULL, if caller
1877 * only intends to ensure the pages are faulted in.
1878 * @vmas: array of pointers to vmas corresponding to each page.
1879 * Or NULL if the caller does not require them.
1880 *
1881 * Returns number of pages pinned. This may be fewer than the number
1882 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1883 * were pinned, returns -errno. Each page returned must be released
1884 * with a put_page() call when it is finished with. vmas will only
1885 * remain valid while mmap_sem is held.
1886 *
1887 * Must be called with mmap_sem held for read or write.
1888 *
1889 * get_user_pages walks a process's page tables and takes a reference to
1890 * each struct page that each user address corresponds to at a given
1891 * instant. That is, it takes the page that would be accessed if a user
1892 * thread accesses the given user virtual address at that instant.
1893 *
1894 * This does not guarantee that the page exists in the user mappings when
1895 * get_user_pages returns, and there may even be a completely different
1896 * page there in some cases (eg. if mmapped pagecache has been invalidated
1897 * and subsequently re faulted). However it does guarantee that the page
1898 * won't be freed completely. And mostly callers simply care that the page
1899 * contains data that was valid *at some point in time*. Typically, an IO
1900 * or similar operation cannot guarantee anything stronger anyway because
1901 * locks can't be held over the syscall boundary.
1902 *
1903 * If write=0, the page must not be written to. If the page is written to,
1904 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1905 * after the page is finished with, and before put_page is called.
1906 *
1907 * get_user_pages is typically used for fewer-copy IO operations, to get a
1908 * handle on the memory by some means other than accesses via the user virtual
1909 * addresses. The pages may be submitted for DMA to devices or accessed via
1910 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1911 * use the correct cache flushing APIs.
1912 *
1913 * See also get_user_pages_fast, for performance critical applications.
1914 */
1915int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1916 unsigned long start, int nr_pages, int write, int force,
1917 struct page **pages, struct vm_area_struct **vmas)
1918{
1919 int flags = FOLL_TOUCH;
1920
1921 if (pages)
1922 flags |= FOLL_GET;
1923 if (write)
1924 flags |= FOLL_WRITE;
1925 if (force)
1926 flags |= FOLL_FORCE;
1927
1928 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1929 NULL);
1930}
1931EXPORT_SYMBOL(get_user_pages);
1932
1933/**
1934 * get_dump_page() - pin user page in memory while writing it to core dump
1935 * @addr: user address
1936 *
1937 * Returns struct page pointer of user page pinned for dump,
1938 * to be freed afterwards by page_cache_release() or put_page().
1939 *
1940 * Returns NULL on any kind of failure - a hole must then be inserted into
1941 * the corefile, to preserve alignment with its headers; and also returns
1942 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1943 * allowing a hole to be left in the corefile to save diskspace.
1944 *
1945 * Called without mmap_sem, but after all other threads have been killed.
1946 */
1947#ifdef CONFIG_ELF_CORE
1948struct page *get_dump_page(unsigned long addr)
1949{
1950 struct vm_area_struct *vma;
1951 struct page *page;
1952
1953 if (__get_user_pages(current, current->mm, addr, 1,
1954 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1955 NULL) < 1)
1956 return NULL;
1957 flush_cache_page(vma, addr, page_to_pfn(page));
1958 return page;
1959}
1960#endif /* CONFIG_ELF_CORE */
1961
1962pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1963 spinlock_t **ptl)
1964{
1965 pgd_t * pgd = pgd_offset(mm, addr);
1966 pud_t * pud = pud_alloc(mm, pgd, addr);
1967 if (pud) {
1968 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1969 if (pmd) {
1970 VM_BUG_ON(pmd_trans_huge(*pmd));
1971 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1972 }
1973 }
1974 return NULL;
1975}
1976
1977/*
1978 * This is the old fallback for page remapping.
1979 *
1980 * For historical reasons, it only allows reserved pages. Only
1981 * old drivers should use this, and they needed to mark their
1982 * pages reserved for the old functions anyway.
1983 */
1984static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1985 struct page *page, pgprot_t prot)
1986{
1987 struct mm_struct *mm = vma->vm_mm;
1988 int retval;
1989 pte_t *pte;
1990 spinlock_t *ptl;
1991
1992 retval = -EINVAL;
1993 if (PageAnon(page))
1994 goto out;
1995 retval = -ENOMEM;
1996 flush_dcache_page(page);
1997 pte = get_locked_pte(mm, addr, &ptl);
1998 if (!pte)
1999 goto out;
2000 retval = -EBUSY;
2001 if (!pte_none(*pte))
2002 goto out_unlock;
2003
2004 /* Ok, finally just insert the thing.. */
2005 get_page(page);
2006 inc_mm_counter_fast(mm, MM_FILEPAGES);
2007 page_add_file_rmap(page);
2008 set_pte_at(mm, addr, pte, mk_pte(page, prot));
2009
2010 retval = 0;
2011 pte_unmap_unlock(pte, ptl);
2012 return retval;
2013out_unlock:
2014 pte_unmap_unlock(pte, ptl);
2015out:
2016 return retval;
2017}
2018
2019/**
2020 * vm_insert_page - insert single page into user vma
2021 * @vma: user vma to map to
2022 * @addr: target user address of this page
2023 * @page: source kernel page
2024 *
2025 * This allows drivers to insert individual pages they've allocated
2026 * into a user vma.
2027 *
2028 * The page has to be a nice clean _individual_ kernel allocation.
2029 * If you allocate a compound page, you need to have marked it as
2030 * such (__GFP_COMP), or manually just split the page up yourself
2031 * (see split_page()).
2032 *
2033 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2034 * took an arbitrary page protection parameter. This doesn't allow
2035 * that. Your vma protection will have to be set up correctly, which
2036 * means that if you want a shared writable mapping, you'd better
2037 * ask for a shared writable mapping!
2038 *
2039 * The page does not need to be reserved.
2040 */
2041int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2042 struct page *page)
2043{
2044 if (addr < vma->vm_start || addr >= vma->vm_end)
2045 return -EFAULT;
2046 if (!page_count(page))
2047 return -EINVAL;
2048 vma->vm_flags |= VM_INSERTPAGE;
2049 return insert_page(vma, addr, page, vma->vm_page_prot);
2050}
2051EXPORT_SYMBOL(vm_insert_page);
2052
2053static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2054 unsigned long pfn, pgprot_t prot)
2055{
2056 struct mm_struct *mm = vma->vm_mm;
2057 int retval;
2058 pte_t *pte, entry;
2059 spinlock_t *ptl;
2060
2061 retval = -ENOMEM;
2062 pte = get_locked_pte(mm, addr, &ptl);
2063 if (!pte)
2064 goto out;
2065 retval = -EBUSY;
2066 if (!pte_none(*pte))
2067 goto out_unlock;
2068
2069 /* Ok, finally just insert the thing.. */
2070 entry = pte_mkspecial(pfn_pte(pfn, prot));
2071 set_pte_at(mm, addr, pte, entry);
2072 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2073
2074 retval = 0;
2075out_unlock:
2076 pte_unmap_unlock(pte, ptl);
2077out:
2078 return retval;
2079}
2080
2081/**
2082 * vm_insert_pfn - insert single pfn into user vma
2083 * @vma: user vma to map to
2084 * @addr: target user address of this page
2085 * @pfn: source kernel pfn
2086 *
2087 * Similar to vm_inert_page, this allows drivers to insert individual pages
2088 * they've allocated into a user vma. Same comments apply.
2089 *
2090 * This function should only be called from a vm_ops->fault handler, and
2091 * in that case the handler should return NULL.
2092 *
2093 * vma cannot be a COW mapping.
2094 *
2095 * As this is called only for pages that do not currently exist, we
2096 * do not need to flush old virtual caches or the TLB.
2097 */
2098int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2099 unsigned long pfn)
2100{
2101 int ret;
2102 pgprot_t pgprot = vma->vm_page_prot;
2103 /*
2104 * Technically, architectures with pte_special can avoid all these
2105 * restrictions (same for remap_pfn_range). However we would like
2106 * consistency in testing and feature parity among all, so we should
2107 * try to keep these invariants in place for everybody.
2108 */
2109 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2110 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2111 (VM_PFNMAP|VM_MIXEDMAP));
2112 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2113 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2114
2115 if (addr < vma->vm_start || addr >= vma->vm_end)
2116 return -EFAULT;
2117 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2118 return -EINVAL;
2119
2120 ret = insert_pfn(vma, addr, pfn, pgprot);
2121
2122 if (ret)
2123 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2124
2125 return ret;
2126}
2127EXPORT_SYMBOL(vm_insert_pfn);
2128
2129int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2130 unsigned long pfn)
2131{
2132 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2133
2134 if (addr < vma->vm_start || addr >= vma->vm_end)
2135 return -EFAULT;
2136
2137 /*
2138 * If we don't have pte special, then we have to use the pfn_valid()
2139 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2140 * refcount the page if pfn_valid is true (hence insert_page rather
2141 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2142 * without pte special, it would there be refcounted as a normal page.
2143 */
2144 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2145 struct page *page;
2146
2147 page = pfn_to_page(pfn);
2148 return insert_page(vma, addr, page, vma->vm_page_prot);
2149 }
2150 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2151}
2152EXPORT_SYMBOL(vm_insert_mixed);
2153
2154/*
2155 * maps a range of physical memory into the requested pages. the old
2156 * mappings are removed. any references to nonexistent pages results
2157 * in null mappings (currently treated as "copy-on-access")
2158 */
2159static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2160 unsigned long addr, unsigned long end,
2161 unsigned long pfn, pgprot_t prot)
2162{
2163 pte_t *pte;
2164 spinlock_t *ptl;
2165
2166 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2167 if (!pte)
2168 return -ENOMEM;
2169 arch_enter_lazy_mmu_mode();
2170 do {
2171 BUG_ON(!pte_none(*pte));
2172 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2173 pfn++;
2174 } while (pte++, addr += PAGE_SIZE, addr != end);
2175 arch_leave_lazy_mmu_mode();
2176 pte_unmap_unlock(pte - 1, ptl);
2177 return 0;
2178}
2179
2180static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2181 unsigned long addr, unsigned long end,
2182 unsigned long pfn, pgprot_t prot)
2183{
2184 pmd_t *pmd;
2185 unsigned long next;
2186
2187 pfn -= addr >> PAGE_SHIFT;
2188 pmd = pmd_alloc(mm, pud, addr);
2189 if (!pmd)
2190 return -ENOMEM;
2191 VM_BUG_ON(pmd_trans_huge(*pmd));
2192 do {
2193 next = pmd_addr_end(addr, end);
2194 if (remap_pte_range(mm, pmd, addr, next,
2195 pfn + (addr >> PAGE_SHIFT), prot))
2196 return -ENOMEM;
2197 } while (pmd++, addr = next, addr != end);
2198 return 0;
2199}
2200
2201static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2202 unsigned long addr, unsigned long end,
2203 unsigned long pfn, pgprot_t prot)
2204{
2205 pud_t *pud;
2206 unsigned long next;
2207
2208 pfn -= addr >> PAGE_SHIFT;
2209 pud = pud_alloc(mm, pgd, addr);
2210 if (!pud)
2211 return -ENOMEM;
2212 do {
2213 next = pud_addr_end(addr, end);
2214 if (remap_pmd_range(mm, pud, addr, next,
2215 pfn + (addr >> PAGE_SHIFT), prot))
2216 return -ENOMEM;
2217 } while (pud++, addr = next, addr != end);
2218 return 0;
2219}
2220
2221/**
2222 * remap_pfn_range - remap kernel memory to userspace
2223 * @vma: user vma to map to
2224 * @addr: target user address to start at
2225 * @pfn: physical address of kernel memory
2226 * @size: size of map area
2227 * @prot: page protection flags for this mapping
2228 *
2229 * Note: this is only safe if the mm semaphore is held when called.
2230 */
2231int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2232 unsigned long pfn, unsigned long size, pgprot_t prot)
2233{
2234 pgd_t *pgd;
2235 unsigned long next;
2236 unsigned long end = addr + PAGE_ALIGN(size);
2237 struct mm_struct *mm = vma->vm_mm;
2238 int err;
2239
2240 /*
2241 * Physically remapped pages are special. Tell the
2242 * rest of the world about it:
2243 * VM_IO tells people not to look at these pages
2244 * (accesses can have side effects).
2245 * VM_RESERVED is specified all over the place, because
2246 * in 2.4 it kept swapout's vma scan off this vma; but
2247 * in 2.6 the LRU scan won't even find its pages, so this
2248 * flag means no more than count its pages in reserved_vm,
2249 * and omit it from core dump, even when VM_IO turned off.
2250 * VM_PFNMAP tells the core MM that the base pages are just
2251 * raw PFN mappings, and do not have a "struct page" associated
2252 * with them.
2253 *
2254 * There's a horrible special case to handle copy-on-write
2255 * behaviour that some programs depend on. We mark the "original"
2256 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2257 */
2258 if (addr == vma->vm_start && end == vma->vm_end) {
2259 vma->vm_pgoff = pfn;
2260 vma->vm_flags |= VM_PFN_AT_MMAP;
2261 } else if (is_cow_mapping(vma->vm_flags))
2262 return -EINVAL;
2263
2264 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2265
2266 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2267 if (err) {
2268 /*
2269 * To indicate that track_pfn related cleanup is not
2270 * needed from higher level routine calling unmap_vmas
2271 */
2272 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2273 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2274 return -EINVAL;
2275 }
2276
2277 BUG_ON(addr >= end);
2278 pfn -= addr >> PAGE_SHIFT;
2279 pgd = pgd_offset(mm, addr);
2280 flush_cache_range(vma, addr, end);
2281 do {
2282 next = pgd_addr_end(addr, end);
2283 err = remap_pud_range(mm, pgd, addr, next,
2284 pfn + (addr >> PAGE_SHIFT), prot);
2285 if (err)
2286 break;
2287 } while (pgd++, addr = next, addr != end);
2288
2289 if (err)
2290 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2291
2292 return err;
2293}
2294EXPORT_SYMBOL(remap_pfn_range);
2295
2296static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2297 unsigned long addr, unsigned long end,
2298 pte_fn_t fn, void *data)
2299{
2300 pte_t *pte;
2301 int err;
2302 pgtable_t token;
2303 spinlock_t *uninitialized_var(ptl);
2304
2305 pte = (mm == &init_mm) ?
2306 pte_alloc_kernel(pmd, addr) :
2307 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2308 if (!pte)
2309 return -ENOMEM;
2310
2311 BUG_ON(pmd_huge(*pmd));
2312
2313 arch_enter_lazy_mmu_mode();
2314
2315 token = pmd_pgtable(*pmd);
2316
2317 do {
2318 err = fn(pte++, token, addr, data);
2319 if (err)
2320 break;
2321 } while (addr += PAGE_SIZE, addr != end);
2322
2323 arch_leave_lazy_mmu_mode();
2324
2325 if (mm != &init_mm)
2326 pte_unmap_unlock(pte-1, ptl);
2327 return err;
2328}
2329
2330static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2331 unsigned long addr, unsigned long end,
2332 pte_fn_t fn, void *data)
2333{
2334 pmd_t *pmd;
2335 unsigned long next;
2336 int err;
2337
2338 BUG_ON(pud_huge(*pud));
2339
2340 pmd = pmd_alloc(mm, pud, addr);
2341 if (!pmd)
2342 return -ENOMEM;
2343 do {
2344 next = pmd_addr_end(addr, end);
2345 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2346 if (err)
2347 break;
2348 } while (pmd++, addr = next, addr != end);
2349 return err;
2350}
2351
2352static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2353 unsigned long addr, unsigned long end,
2354 pte_fn_t fn, void *data)
2355{
2356 pud_t *pud;
2357 unsigned long next;
2358 int err;
2359
2360 pud = pud_alloc(mm, pgd, addr);
2361 if (!pud)
2362 return -ENOMEM;
2363 do {
2364 next = pud_addr_end(addr, end);
2365 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2366 if (err)
2367 break;
2368 } while (pud++, addr = next, addr != end);
2369 return err;
2370}
2371
2372/*
2373 * Scan a region of virtual memory, filling in page tables as necessary
2374 * and calling a provided function on each leaf page table.
2375 */
2376int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2377 unsigned long size, pte_fn_t fn, void *data)
2378{
2379 pgd_t *pgd;
2380 unsigned long next;
2381 unsigned long end = addr + size;
2382 int err;
2383
2384 BUG_ON(addr >= end);
2385 pgd = pgd_offset(mm, addr);
2386 do {
2387 next = pgd_addr_end(addr, end);
2388 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2389 if (err)
2390 break;
2391 } while (pgd++, addr = next, addr != end);
2392
2393 return err;
2394}
2395EXPORT_SYMBOL_GPL(apply_to_page_range);
2396
2397/*
2398 * handle_pte_fault chooses page fault handler according to an entry
2399 * which was read non-atomically. Before making any commitment, on
2400 * those architectures or configurations (e.g. i386 with PAE) which
2401 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2402 * must check under lock before unmapping the pte and proceeding
2403 * (but do_wp_page is only called after already making such a check;
2404 * and do_anonymous_page can safely check later on).
2405 */
2406static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2407 pte_t *page_table, pte_t orig_pte)
2408{
2409 int same = 1;
2410#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2411 if (sizeof(pte_t) > sizeof(unsigned long)) {
2412 spinlock_t *ptl = pte_lockptr(mm, pmd);
2413 spin_lock(ptl);
2414 same = pte_same(*page_table, orig_pte);
2415 spin_unlock(ptl);
2416 }
2417#endif
2418 pte_unmap(page_table);
2419 return same;
2420}
2421
2422static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2423{
2424 /*
2425 * If the source page was a PFN mapping, we don't have
2426 * a "struct page" for it. We do a best-effort copy by
2427 * just copying from the original user address. If that
2428 * fails, we just zero-fill it. Live with it.
2429 */
2430 if (unlikely(!src)) {
2431 void *kaddr = kmap_atomic(dst, KM_USER0);
2432 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2433
2434 /*
2435 * This really shouldn't fail, because the page is there
2436 * in the page tables. But it might just be unreadable,
2437 * in which case we just give up and fill the result with
2438 * zeroes.
2439 */
2440 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2441 clear_page(kaddr);
2442 kunmap_atomic(kaddr, KM_USER0);
2443 flush_dcache_page(dst);
2444 } else
2445 copy_user_highpage(dst, src, va, vma);
2446}
2447
2448/*
2449 * This routine handles present pages, when users try to write
2450 * to a shared page. It is done by copying the page to a new address
2451 * and decrementing the shared-page counter for the old page.
2452 *
2453 * Note that this routine assumes that the protection checks have been
2454 * done by the caller (the low-level page fault routine in most cases).
2455 * Thus we can safely just mark it writable once we've done any necessary
2456 * COW.
2457 *
2458 * We also mark the page dirty at this point even though the page will
2459 * change only once the write actually happens. This avoids a few races,
2460 * and potentially makes it more efficient.
2461 *
2462 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2463 * but allow concurrent faults), with pte both mapped and locked.
2464 * We return with mmap_sem still held, but pte unmapped and unlocked.
2465 */
2466static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2467 unsigned long address, pte_t *page_table, pmd_t *pmd,
2468 spinlock_t *ptl, pte_t orig_pte)
2469 __releases(ptl)
2470{
2471 struct page *old_page, *new_page;
2472 pte_t entry;
2473 int ret = 0;
2474 int page_mkwrite = 0;
2475 struct page *dirty_page = NULL;
2476
2477 old_page = vm_normal_page(vma, address, orig_pte);
2478 if (!old_page) {
2479 /*
2480 * VM_MIXEDMAP !pfn_valid() case
2481 *
2482 * We should not cow pages in a shared writeable mapping.
2483 * Just mark the pages writable as we can't do any dirty
2484 * accounting on raw pfn maps.
2485 */
2486 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2487 (VM_WRITE|VM_SHARED))
2488 goto reuse;
2489 goto gotten;
2490 }
2491
2492 /*
2493 * Take out anonymous pages first, anonymous shared vmas are
2494 * not dirty accountable.
2495 */
2496 if (PageAnon(old_page) && !PageKsm(old_page)) {
2497 if (!trylock_page(old_page)) {
2498 page_cache_get(old_page);
2499 pte_unmap_unlock(page_table, ptl);
2500 lock_page(old_page);
2501 page_table = pte_offset_map_lock(mm, pmd, address,
2502 &ptl);
2503 if (!pte_same(*page_table, orig_pte)) {
2504 unlock_page(old_page);
2505 goto unlock;
2506 }
2507 page_cache_release(old_page);
2508 }
2509 if (reuse_swap_page(old_page)) {
2510 /*
2511 * The page is all ours. Move it to our anon_vma so
2512 * the rmap code will not search our parent or siblings.
2513 * Protected against the rmap code by the page lock.
2514 */
2515 page_move_anon_rmap(old_page, vma, address);
2516 unlock_page(old_page);
2517 goto reuse;
2518 }
2519 unlock_page(old_page);
2520 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2521 (VM_WRITE|VM_SHARED))) {
2522 /*
2523 * Only catch write-faults on shared writable pages,
2524 * read-only shared pages can get COWed by
2525 * get_user_pages(.write=1, .force=1).
2526 */
2527 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2528 struct vm_fault vmf;
2529 int tmp;
2530
2531 vmf.virtual_address = (void __user *)(address &
2532 PAGE_MASK);
2533 vmf.pgoff = old_page->index;
2534 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2535 vmf.page = old_page;
2536
2537 /*
2538 * Notify the address space that the page is about to
2539 * become writable so that it can prohibit this or wait
2540 * for the page to get into an appropriate state.
2541 *
2542 * We do this without the lock held, so that it can
2543 * sleep if it needs to.
2544 */
2545 page_cache_get(old_page);
2546 pte_unmap_unlock(page_table, ptl);
2547
2548 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2549 if (unlikely(tmp &
2550 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2551 ret = tmp;
2552 goto unwritable_page;
2553 }
2554 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2555 lock_page(old_page);
2556 if (!old_page->mapping) {
2557 ret = 0; /* retry the fault */
2558 unlock_page(old_page);
2559 goto unwritable_page;
2560 }
2561 } else
2562 VM_BUG_ON(!PageLocked(old_page));
2563
2564 /*
2565 * Since we dropped the lock we need to revalidate
2566 * the PTE as someone else may have changed it. If
2567 * they did, we just return, as we can count on the
2568 * MMU to tell us if they didn't also make it writable.
2569 */
2570 page_table = pte_offset_map_lock(mm, pmd, address,
2571 &ptl);
2572 if (!pte_same(*page_table, orig_pte)) {
2573 unlock_page(old_page);
2574 goto unlock;
2575 }
2576
2577 page_mkwrite = 1;
2578 }
2579 dirty_page = old_page;
2580 get_page(dirty_page);
2581
2582reuse:
2583 flush_cache_page(vma, address, pte_pfn(orig_pte));
2584 entry = pte_mkyoung(orig_pte);
2585 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2586 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2587 update_mmu_cache(vma, address, page_table);
2588 pte_unmap_unlock(page_table, ptl);
2589 ret |= VM_FAULT_WRITE;
2590
2591 if (!dirty_page)
2592 return ret;
2593
2594 /*
2595 * Yes, Virginia, this is actually required to prevent a race
2596 * with clear_page_dirty_for_io() from clearing the page dirty
2597 * bit after it clear all dirty ptes, but before a racing
2598 * do_wp_page installs a dirty pte.
2599 *
2600 * __do_fault is protected similarly.
2601 */
2602 if (!page_mkwrite) {
2603 wait_on_page_locked(dirty_page);
2604 set_page_dirty_balance(dirty_page, page_mkwrite);
2605 }
2606 put_page(dirty_page);
2607 if (page_mkwrite) {
2608 struct address_space *mapping = dirty_page->mapping;
2609
2610 set_page_dirty(dirty_page);
2611 unlock_page(dirty_page);
2612 page_cache_release(dirty_page);
2613 if (mapping) {
2614 /*
2615 * Some device drivers do not set page.mapping
2616 * but still dirty their pages
2617 */
2618 balance_dirty_pages_ratelimited(mapping);
2619 }
2620 }
2621
2622 /* file_update_time outside page_lock */
2623 if (vma->vm_file)
2624 file_update_time(vma->vm_file);
2625
2626 return ret;
2627 }
2628
2629 /*
2630 * Ok, we need to copy. Oh, well..
2631 */
2632 page_cache_get(old_page);
2633gotten:
2634 pte_unmap_unlock(page_table, ptl);
2635
2636 if (unlikely(anon_vma_prepare(vma)))
2637 goto oom;
2638
2639 if (is_zero_pfn(pte_pfn(orig_pte))) {
2640 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2641 if (!new_page)
2642 goto oom;
2643 } else {
2644 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2645 if (!new_page)
2646 goto oom;
2647 cow_user_page(new_page, old_page, address, vma);
2648 }
2649 __SetPageUptodate(new_page);
2650
2651 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2652 goto oom_free_new;
2653
2654 /*
2655 * Re-check the pte - we dropped the lock
2656 */
2657 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2658 if (likely(pte_same(*page_table, orig_pte))) {
2659 if (old_page) {
2660 if (!PageAnon(old_page)) {
2661 dec_mm_counter_fast(mm, MM_FILEPAGES);
2662 inc_mm_counter_fast(mm, MM_ANONPAGES);
2663 }
2664 } else
2665 inc_mm_counter_fast(mm, MM_ANONPAGES);
2666 flush_cache_page(vma, address, pte_pfn(orig_pte));
2667 entry = mk_pte(new_page, vma->vm_page_prot);
2668 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2669 /*
2670 * Clear the pte entry and flush it first, before updating the
2671 * pte with the new entry. This will avoid a race condition
2672 * seen in the presence of one thread doing SMC and another
2673 * thread doing COW.
2674 */
2675 ptep_clear_flush(vma, address, page_table);
2676 page_add_new_anon_rmap(new_page, vma, address);
2677 /*
2678 * We call the notify macro here because, when using secondary
2679 * mmu page tables (such as kvm shadow page tables), we want the
2680 * new page to be mapped directly into the secondary page table.
2681 */
2682 set_pte_at_notify(mm, address, page_table, entry);
2683 update_mmu_cache(vma, address, page_table);
2684 if (old_page) {
2685 /*
2686 * Only after switching the pte to the new page may
2687 * we remove the mapcount here. Otherwise another
2688 * process may come and find the rmap count decremented
2689 * before the pte is switched to the new page, and
2690 * "reuse" the old page writing into it while our pte
2691 * here still points into it and can be read by other
2692 * threads.
2693 *
2694 * The critical issue is to order this
2695 * page_remove_rmap with the ptp_clear_flush above.
2696 * Those stores are ordered by (if nothing else,)
2697 * the barrier present in the atomic_add_negative
2698 * in page_remove_rmap.
2699 *
2700 * Then the TLB flush in ptep_clear_flush ensures that
2701 * no process can access the old page before the
2702 * decremented mapcount is visible. And the old page
2703 * cannot be reused until after the decremented
2704 * mapcount is visible. So transitively, TLBs to
2705 * old page will be flushed before it can be reused.
2706 */
2707 page_remove_rmap(old_page);
2708 }
2709
2710 /* Free the old page.. */
2711 new_page = old_page;
2712 ret |= VM_FAULT_WRITE;
2713 } else
2714 mem_cgroup_uncharge_page(new_page);
2715
2716 if (new_page)
2717 page_cache_release(new_page);
2718unlock:
2719 pte_unmap_unlock(page_table, ptl);
2720 if (old_page) {
2721 /*
2722 * Don't let another task, with possibly unlocked vma,
2723 * keep the mlocked page.
2724 */
2725 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2726 lock_page(old_page); /* LRU manipulation */
2727 munlock_vma_page(old_page);
2728 unlock_page(old_page);
2729 }
2730 page_cache_release(old_page);
2731 }
2732 return ret;
2733oom_free_new:
2734 page_cache_release(new_page);
2735oom:
2736 if (old_page) {
2737 if (page_mkwrite) {
2738 unlock_page(old_page);
2739 page_cache_release(old_page);
2740 }
2741 page_cache_release(old_page);
2742 }
2743 return VM_FAULT_OOM;
2744
2745unwritable_page:
2746 page_cache_release(old_page);
2747 return ret;
2748}
2749
2750static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2751 unsigned long start_addr, unsigned long end_addr,
2752 struct zap_details *details)
2753{
2754 zap_page_range(vma, start_addr, end_addr - start_addr, details);
2755}
2756
2757static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2758 struct zap_details *details)
2759{
2760 struct vm_area_struct *vma;
2761 struct prio_tree_iter iter;
2762 pgoff_t vba, vea, zba, zea;
2763
2764 vma_prio_tree_foreach(vma, &iter, root,
2765 details->first_index, details->last_index) {
2766
2767 vba = vma->vm_pgoff;
2768 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2769 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2770 zba = details->first_index;
2771 if (zba < vba)
2772 zba = vba;
2773 zea = details->last_index;
2774 if (zea > vea)
2775 zea = vea;
2776
2777 unmap_mapping_range_vma(vma,
2778 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2779 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2780 details);
2781 }
2782}
2783
2784static inline void unmap_mapping_range_list(struct list_head *head,
2785 struct zap_details *details)
2786{
2787 struct vm_area_struct *vma;
2788
2789 /*
2790 * In nonlinear VMAs there is no correspondence between virtual address
2791 * offset and file offset. So we must perform an exhaustive search
2792 * across *all* the pages in each nonlinear VMA, not just the pages
2793 * whose virtual address lies outside the file truncation point.
2794 */
2795 list_for_each_entry(vma, head, shared.vm_set.list) {
2796 details->nonlinear_vma = vma;
2797 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2798 }
2799}
2800
2801/**
2802 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2803 * @mapping: the address space containing mmaps to be unmapped.
2804 * @holebegin: byte in first page to unmap, relative to the start of
2805 * the underlying file. This will be rounded down to a PAGE_SIZE
2806 * boundary. Note that this is different from truncate_pagecache(), which
2807 * must keep the partial page. In contrast, we must get rid of
2808 * partial pages.
2809 * @holelen: size of prospective hole in bytes. This will be rounded
2810 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2811 * end of the file.
2812 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2813 * but 0 when invalidating pagecache, don't throw away private data.
2814 */
2815void unmap_mapping_range(struct address_space *mapping,
2816 loff_t const holebegin, loff_t const holelen, int even_cows)
2817{
2818 struct zap_details details;
2819 pgoff_t hba = holebegin >> PAGE_SHIFT;
2820 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2821
2822 /* Check for overflow. */
2823 if (sizeof(holelen) > sizeof(hlen)) {
2824 long long holeend =
2825 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2826 if (holeend & ~(long long)ULONG_MAX)
2827 hlen = ULONG_MAX - hba + 1;
2828 }
2829
2830 details.check_mapping = even_cows? NULL: mapping;
2831 details.nonlinear_vma = NULL;
2832 details.first_index = hba;
2833 details.last_index = hba + hlen - 1;
2834 if (details.last_index < details.first_index)
2835 details.last_index = ULONG_MAX;
2836
2837
2838 mutex_lock(&mapping->i_mmap_mutex);
2839 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2840 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2841 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2842 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2843 mutex_unlock(&mapping->i_mmap_mutex);
2844}
2845EXPORT_SYMBOL(unmap_mapping_range);
2846
2847/*
2848 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2849 * but allow concurrent faults), and pte mapped but not yet locked.
2850 * We return with mmap_sem still held, but pte unmapped and unlocked.
2851 */
2852static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2853 unsigned long address, pte_t *page_table, pmd_t *pmd,
2854 unsigned int flags, pte_t orig_pte)
2855{
2856 spinlock_t *ptl;
2857 struct page *page, *swapcache = NULL;
2858 swp_entry_t entry;
2859 pte_t pte;
2860 int locked;
2861 struct mem_cgroup *ptr;
2862 int exclusive = 0;
2863 int ret = 0;
2864
2865 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2866 goto out;
2867
2868 entry = pte_to_swp_entry(orig_pte);
2869 if (unlikely(non_swap_entry(entry))) {
2870 if (is_migration_entry(entry)) {
2871 migration_entry_wait(mm, pmd, address);
2872 } else if (is_hwpoison_entry(entry)) {
2873 ret = VM_FAULT_HWPOISON;
2874 } else {
2875 print_bad_pte(vma, address, orig_pte, NULL);
2876 ret = VM_FAULT_SIGBUS;
2877 }
2878 goto out;
2879 }
2880 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2881 page = lookup_swap_cache(entry);
2882 if (!page) {
2883 grab_swap_token(mm); /* Contend for token _before_ read-in */
2884 page = swapin_readahead(entry,
2885 GFP_HIGHUSER_MOVABLE, vma, address);
2886 if (!page) {
2887 /*
2888 * Back out if somebody else faulted in this pte
2889 * while we released the pte lock.
2890 */
2891 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2892 if (likely(pte_same(*page_table, orig_pte)))
2893 ret = VM_FAULT_OOM;
2894 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2895 goto unlock;
2896 }
2897
2898 /* Had to read the page from swap area: Major fault */
2899 ret = VM_FAULT_MAJOR;
2900 count_vm_event(PGMAJFAULT);
2901 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2902 } else if (PageHWPoison(page)) {
2903 /*
2904 * hwpoisoned dirty swapcache pages are kept for killing
2905 * owner processes (which may be unknown at hwpoison time)
2906 */
2907 ret = VM_FAULT_HWPOISON;
2908 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2909 goto out_release;
2910 }
2911
2912 locked = lock_page_or_retry(page, mm, flags);
2913 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2914 if (!locked) {
2915 ret |= VM_FAULT_RETRY;
2916 goto out_release;
2917 }
2918
2919 /*
2920 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2921 * release the swapcache from under us. The page pin, and pte_same
2922 * test below, are not enough to exclude that. Even if it is still
2923 * swapcache, we need to check that the page's swap has not changed.
2924 */
2925 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2926 goto out_page;
2927
2928 if (ksm_might_need_to_copy(page, vma, address)) {
2929 swapcache = page;
2930 page = ksm_does_need_to_copy(page, vma, address);
2931
2932 if (unlikely(!page)) {
2933 ret = VM_FAULT_OOM;
2934 page = swapcache;
2935 swapcache = NULL;
2936 goto out_page;
2937 }
2938 }
2939
2940 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2941 ret = VM_FAULT_OOM;
2942 goto out_page;
2943 }
2944
2945 /*
2946 * Back out if somebody else already faulted in this pte.
2947 */
2948 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2949 if (unlikely(!pte_same(*page_table, orig_pte)))
2950 goto out_nomap;
2951
2952 if (unlikely(!PageUptodate(page))) {
2953 ret = VM_FAULT_SIGBUS;
2954 goto out_nomap;
2955 }
2956
2957 /*
2958 * The page isn't present yet, go ahead with the fault.
2959 *
2960 * Be careful about the sequence of operations here.
2961 * To get its accounting right, reuse_swap_page() must be called
2962 * while the page is counted on swap but not yet in mapcount i.e.
2963 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2964 * must be called after the swap_free(), or it will never succeed.
2965 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2966 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2967 * in page->private. In this case, a record in swap_cgroup is silently
2968 * discarded at swap_free().
2969 */
2970
2971 inc_mm_counter_fast(mm, MM_ANONPAGES);
2972 dec_mm_counter_fast(mm, MM_SWAPENTS);
2973 pte = mk_pte(page, vma->vm_page_prot);
2974 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2975 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2976 flags &= ~FAULT_FLAG_WRITE;
2977 ret |= VM_FAULT_WRITE;
2978 exclusive = 1;
2979 }
2980 flush_icache_page(vma, page);
2981 set_pte_at(mm, address, page_table, pte);
2982 do_page_add_anon_rmap(page, vma, address, exclusive);
2983 /* It's better to call commit-charge after rmap is established */
2984 mem_cgroup_commit_charge_swapin(page, ptr);
2985
2986 swap_free(entry);
2987 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2988 try_to_free_swap(page);
2989 unlock_page(page);
2990 if (swapcache) {
2991 /*
2992 * Hold the lock to avoid the swap entry to be reused
2993 * until we take the PT lock for the pte_same() check
2994 * (to avoid false positives from pte_same). For
2995 * further safety release the lock after the swap_free
2996 * so that the swap count won't change under a
2997 * parallel locked swapcache.
2998 */
2999 unlock_page(swapcache);
3000 page_cache_release(swapcache);
3001 }
3002
3003 if (flags & FAULT_FLAG_WRITE) {
3004 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3005 if (ret & VM_FAULT_ERROR)
3006 ret &= VM_FAULT_ERROR;
3007 goto out;
3008 }
3009
3010 /* No need to invalidate - it was non-present before */
3011 update_mmu_cache(vma, address, page_table);
3012unlock:
3013 pte_unmap_unlock(page_table, ptl);
3014out:
3015 return ret;
3016out_nomap:
3017 mem_cgroup_cancel_charge_swapin(ptr);
3018 pte_unmap_unlock(page_table, ptl);
3019out_page:
3020 unlock_page(page);
3021out_release:
3022 page_cache_release(page);
3023 if (swapcache) {
3024 unlock_page(swapcache);
3025 page_cache_release(swapcache);
3026 }
3027 return ret;
3028}
3029
3030/*
3031 * This is like a special single-page "expand_{down|up}wards()",
3032 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3033 * doesn't hit another vma.
3034 */
3035static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3036{
3037 address &= PAGE_MASK;
3038 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3039 struct vm_area_struct *prev = vma->vm_prev;
3040
3041 /*
3042 * Is there a mapping abutting this one below?
3043 *
3044 * That's only ok if it's the same stack mapping
3045 * that has gotten split..
3046 */
3047 if (prev && prev->vm_end == address)
3048 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3049
3050 expand_downwards(vma, address - PAGE_SIZE);
3051 }
3052 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3053 struct vm_area_struct *next = vma->vm_next;
3054
3055 /* As VM_GROWSDOWN but s/below/above/ */
3056 if (next && next->vm_start == address + PAGE_SIZE)
3057 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3058
3059 expand_upwards(vma, address + PAGE_SIZE);
3060 }
3061 return 0;
3062}
3063
3064/*
3065 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3066 * but allow concurrent faults), and pte mapped but not yet locked.
3067 * We return with mmap_sem still held, but pte unmapped and unlocked.
3068 */
3069static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3070 unsigned long address, pte_t *page_table, pmd_t *pmd,
3071 unsigned int flags)
3072{
3073 struct page *page;
3074 spinlock_t *ptl;
3075 pte_t entry;
3076
3077 pte_unmap(page_table);
3078
3079 /* Check if we need to add a guard page to the stack */
3080 if (check_stack_guard_page(vma, address) < 0)
3081 return VM_FAULT_SIGBUS;
3082
3083 /* Use the zero-page for reads */
3084 if (!(flags & FAULT_FLAG_WRITE)) {
3085 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3086 vma->vm_page_prot));
3087 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3088 if (!pte_none(*page_table))
3089 goto unlock;
3090 goto setpte;
3091 }
3092
3093 /* Allocate our own private page. */
3094 if (unlikely(anon_vma_prepare(vma)))
3095 goto oom;
3096 page = alloc_zeroed_user_highpage_movable(vma, address);
3097 if (!page)
3098 goto oom;
3099 __SetPageUptodate(page);
3100
3101 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3102 goto oom_free_page;
3103
3104 entry = mk_pte(page, vma->vm_page_prot);
3105 if (vma->vm_flags & VM_WRITE)
3106 entry = pte_mkwrite(pte_mkdirty(entry));
3107
3108 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3109 if (!pte_none(*page_table))
3110 goto release;
3111
3112 inc_mm_counter_fast(mm, MM_ANONPAGES);
3113 page_add_new_anon_rmap(page, vma, address);
3114setpte:
3115 set_pte_at(mm, address, page_table, entry);
3116
3117 /* No need to invalidate - it was non-present before */
3118 update_mmu_cache(vma, address, page_table);
3119unlock:
3120 pte_unmap_unlock(page_table, ptl);
3121 return 0;
3122release:
3123 mem_cgroup_uncharge_page(page);
3124 page_cache_release(page);
3125 goto unlock;
3126oom_free_page:
3127 page_cache_release(page);
3128oom:
3129 return VM_FAULT_OOM;
3130}
3131
3132/*
3133 * __do_fault() tries to create a new page mapping. It aggressively
3134 * tries to share with existing pages, but makes a separate copy if
3135 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3136 * the next page fault.
3137 *
3138 * As this is called only for pages that do not currently exist, we
3139 * do not need to flush old virtual caches or the TLB.
3140 *
3141 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3142 * but allow concurrent faults), and pte neither mapped nor locked.
3143 * We return with mmap_sem still held, but pte unmapped and unlocked.
3144 */
3145static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3146 unsigned long address, pmd_t *pmd,
3147 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3148{
3149 pte_t *page_table;
3150 spinlock_t *ptl;
3151 struct page *page;
3152 struct page *cow_page;
3153 pte_t entry;
3154 int anon = 0;
3155 struct page *dirty_page = NULL;
3156 struct vm_fault vmf;
3157 int ret;
3158 int page_mkwrite = 0;
3159
3160 /*
3161 * If we do COW later, allocate page befor taking lock_page()
3162 * on the file cache page. This will reduce lock holding time.
3163 */
3164 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3165
3166 if (unlikely(anon_vma_prepare(vma)))
3167 return VM_FAULT_OOM;
3168
3169 cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3170 if (!cow_page)
3171 return VM_FAULT_OOM;
3172
3173 if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3174 page_cache_release(cow_page);
3175 return VM_FAULT_OOM;
3176 }
3177 } else
3178 cow_page = NULL;
3179
3180 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3181 vmf.pgoff = pgoff;
3182 vmf.flags = flags;
3183 vmf.page = NULL;
3184
3185 ret = vma->vm_ops->fault(vma, &vmf);
3186 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3187 VM_FAULT_RETRY)))
3188 goto uncharge_out;
3189
3190 if (unlikely(PageHWPoison(vmf.page))) {
3191 if (ret & VM_FAULT_LOCKED)
3192 unlock_page(vmf.page);
3193 ret = VM_FAULT_HWPOISON;
3194 goto uncharge_out;
3195 }
3196
3197 /*
3198 * For consistency in subsequent calls, make the faulted page always
3199 * locked.
3200 */
3201 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3202 lock_page(vmf.page);
3203 else
3204 VM_BUG_ON(!PageLocked(vmf.page));
3205
3206 /*
3207 * Should we do an early C-O-W break?
3208 */
3209 page = vmf.page;
3210 if (flags & FAULT_FLAG_WRITE) {
3211 if (!(vma->vm_flags & VM_SHARED)) {
3212 page = cow_page;
3213 anon = 1;
3214 copy_user_highpage(page, vmf.page, address, vma);
3215 __SetPageUptodate(page);
3216 } else {
3217 /*
3218 * If the page will be shareable, see if the backing
3219 * address space wants to know that the page is about
3220 * to become writable
3221 */
3222 if (vma->vm_ops->page_mkwrite) {
3223 int tmp;
3224
3225 unlock_page(page);
3226 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3227 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3228 if (unlikely(tmp &
3229 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3230 ret = tmp;
3231 goto unwritable_page;
3232 }
3233 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3234 lock_page(page);
3235 if (!page->mapping) {
3236 ret = 0; /* retry the fault */
3237 unlock_page(page);
3238 goto unwritable_page;
3239 }
3240 } else
3241 VM_BUG_ON(!PageLocked(page));
3242 page_mkwrite = 1;
3243 }
3244 }
3245
3246 }
3247
3248 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3249
3250 /*
3251 * This silly early PAGE_DIRTY setting removes a race
3252 * due to the bad i386 page protection. But it's valid
3253 * for other architectures too.
3254 *
3255 * Note that if FAULT_FLAG_WRITE is set, we either now have
3256 * an exclusive copy of the page, or this is a shared mapping,
3257 * so we can make it writable and dirty to avoid having to
3258 * handle that later.
3259 */
3260 /* Only go through if we didn't race with anybody else... */
3261 if (likely(pte_same(*page_table, orig_pte))) {
3262 flush_icache_page(vma, page);
3263 entry = mk_pte(page, vma->vm_page_prot);
3264 if (flags & FAULT_FLAG_WRITE)
3265 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3266 if (anon) {
3267 inc_mm_counter_fast(mm, MM_ANONPAGES);
3268 page_add_new_anon_rmap(page, vma, address);
3269 } else {
3270 inc_mm_counter_fast(mm, MM_FILEPAGES);
3271 page_add_file_rmap(page);
3272 if (flags & FAULT_FLAG_WRITE) {
3273 dirty_page = page;
3274 get_page(dirty_page);
3275 }
3276 }
3277 set_pte_at(mm, address, page_table, entry);
3278
3279 /* no need to invalidate: a not-present page won't be cached */
3280 update_mmu_cache(vma, address, page_table);
3281 } else {
3282 if (cow_page)
3283 mem_cgroup_uncharge_page(cow_page);
3284 if (anon)
3285 page_cache_release(page);
3286 else
3287 anon = 1; /* no anon but release faulted_page */
3288 }
3289
3290 pte_unmap_unlock(page_table, ptl);
3291
3292 if (dirty_page) {
3293 struct address_space *mapping = page->mapping;
3294
3295 if (set_page_dirty(dirty_page))
3296 page_mkwrite = 1;
3297 unlock_page(dirty_page);
3298 put_page(dirty_page);
3299 if (page_mkwrite && mapping) {
3300 /*
3301 * Some device drivers do not set page.mapping but still
3302 * dirty their pages
3303 */
3304 balance_dirty_pages_ratelimited(mapping);
3305 }
3306
3307 /* file_update_time outside page_lock */
3308 if (vma->vm_file)
3309 file_update_time(vma->vm_file);
3310 } else {
3311 unlock_page(vmf.page);
3312 if (anon)
3313 page_cache_release(vmf.page);
3314 }
3315
3316 return ret;
3317
3318unwritable_page:
3319 page_cache_release(page);
3320 return ret;
3321uncharge_out:
3322 /* fs's fault handler get error */
3323 if (cow_page) {
3324 mem_cgroup_uncharge_page(cow_page);
3325 page_cache_release(cow_page);
3326 }
3327 return ret;
3328}
3329
3330static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3331 unsigned long address, pte_t *page_table, pmd_t *pmd,
3332 unsigned int flags, pte_t orig_pte)
3333{
3334 pgoff_t pgoff = (((address & PAGE_MASK)
3335 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3336
3337 pte_unmap(page_table);
3338 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3339}
3340
3341/*
3342 * Fault of a previously existing named mapping. Repopulate the pte
3343 * from the encoded file_pte if possible. This enables swappable
3344 * nonlinear vmas.
3345 *
3346 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3347 * but allow concurrent faults), and pte mapped but not yet locked.
3348 * We return with mmap_sem still held, but pte unmapped and unlocked.
3349 */
3350static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3351 unsigned long address, pte_t *page_table, pmd_t *pmd,
3352 unsigned int flags, pte_t orig_pte)
3353{
3354 pgoff_t pgoff;
3355
3356 flags |= FAULT_FLAG_NONLINEAR;
3357
3358 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3359 return 0;
3360
3361 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3362 /*
3363 * Page table corrupted: show pte and kill process.
3364 */
3365 print_bad_pte(vma, address, orig_pte, NULL);
3366 return VM_FAULT_SIGBUS;
3367 }
3368
3369 pgoff = pte_to_pgoff(orig_pte);
3370 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3371}
3372
3373/*
3374 * These routines also need to handle stuff like marking pages dirty
3375 * and/or accessed for architectures that don't do it in hardware (most
3376 * RISC architectures). The early dirtying is also good on the i386.
3377 *
3378 * There is also a hook called "update_mmu_cache()" that architectures
3379 * with external mmu caches can use to update those (ie the Sparc or
3380 * PowerPC hashed page tables that act as extended TLBs).
3381 *
3382 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3383 * but allow concurrent faults), and pte mapped but not yet locked.
3384 * We return with mmap_sem still held, but pte unmapped and unlocked.
3385 */
3386int handle_pte_fault(struct mm_struct *mm,
3387 struct vm_area_struct *vma, unsigned long address,
3388 pte_t *pte, pmd_t *pmd, unsigned int flags)
3389{
3390 pte_t entry;
3391 spinlock_t *ptl;
3392
3393 entry = *pte;
3394 if (!pte_present(entry)) {
3395 if (pte_none(entry)) {
3396 if (vma->vm_ops) {
3397 if (likely(vma->vm_ops->fault))
3398 return do_linear_fault(mm, vma, address,
3399 pte, pmd, flags, entry);
3400 }
3401 return do_anonymous_page(mm, vma, address,
3402 pte, pmd, flags);
3403 }
3404 if (pte_file(entry))
3405 return do_nonlinear_fault(mm, vma, address,
3406 pte, pmd, flags, entry);
3407 return do_swap_page(mm, vma, address,
3408 pte, pmd, flags, entry);
3409 }
3410
3411 ptl = pte_lockptr(mm, pmd);
3412 spin_lock(ptl);
3413 if (unlikely(!pte_same(*pte, entry)))
3414 goto unlock;
3415 if (flags & FAULT_FLAG_WRITE) {
3416 if (!pte_write(entry))
3417 return do_wp_page(mm, vma, address,
3418 pte, pmd, ptl, entry);
3419 entry = pte_mkdirty(entry);
3420 }
3421 entry = pte_mkyoung(entry);
3422 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3423 update_mmu_cache(vma, address, pte);
3424 } else {
3425 /*
3426 * This is needed only for protection faults but the arch code
3427 * is not yet telling us if this is a protection fault or not.
3428 * This still avoids useless tlb flushes for .text page faults
3429 * with threads.
3430 */
3431 if (flags & FAULT_FLAG_WRITE)
3432 flush_tlb_fix_spurious_fault(vma, address);
3433 }
3434unlock:
3435 pte_unmap_unlock(pte, ptl);
3436 return 0;
3437}
3438
3439/*
3440 * By the time we get here, we already hold the mm semaphore
3441 */
3442int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3443 unsigned long address, unsigned int flags)
3444{
3445 pgd_t *pgd;
3446 pud_t *pud;
3447 pmd_t *pmd;
3448 pte_t *pte;
3449
3450 __set_current_state(TASK_RUNNING);
3451
3452 count_vm_event(PGFAULT);
3453 mem_cgroup_count_vm_event(mm, PGFAULT);
3454
3455 /* do counter updates before entering really critical section. */
3456 check_sync_rss_stat(current);
3457
3458 if (unlikely(is_vm_hugetlb_page(vma)))
3459 return hugetlb_fault(mm, vma, address, flags);
3460
3461 pgd = pgd_offset(mm, address);
3462 pud = pud_alloc(mm, pgd, address);
3463 if (!pud)
3464 return VM_FAULT_OOM;
3465 pmd = pmd_alloc(mm, pud, address);
3466 if (!pmd)
3467 return VM_FAULT_OOM;
3468 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3469 if (!vma->vm_ops)
3470 return do_huge_pmd_anonymous_page(mm, vma, address,
3471 pmd, flags);
3472 } else {
3473 pmd_t orig_pmd = *pmd;
3474 barrier();
3475 if (pmd_trans_huge(orig_pmd)) {
3476 if (flags & FAULT_FLAG_WRITE &&
3477 !pmd_write(orig_pmd) &&
3478 !pmd_trans_splitting(orig_pmd))
3479 return do_huge_pmd_wp_page(mm, vma, address,
3480 pmd, orig_pmd);
3481 return 0;
3482 }
3483 }
3484
3485 /*
3486 * Use __pte_alloc instead of pte_alloc_map, because we can't
3487 * run pte_offset_map on the pmd, if an huge pmd could
3488 * materialize from under us from a different thread.
3489 */
3490 if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3491 return VM_FAULT_OOM;
3492 /* if an huge pmd materialized from under us just retry later */
3493 if (unlikely(pmd_trans_huge(*pmd)))
3494 return 0;
3495 /*
3496 * A regular pmd is established and it can't morph into a huge pmd
3497 * from under us anymore at this point because we hold the mmap_sem
3498 * read mode and khugepaged takes it in write mode. So now it's
3499 * safe to run pte_offset_map().
3500 */
3501 pte = pte_offset_map(pmd, address);
3502
3503 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3504}
3505
3506#ifndef __PAGETABLE_PUD_FOLDED
3507/*
3508 * Allocate page upper directory.
3509 * We've already handled the fast-path in-line.
3510 */
3511int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3512{
3513 pud_t *new = pud_alloc_one(mm, address);
3514 if (!new)
3515 return -ENOMEM;
3516
3517 smp_wmb(); /* See comment in __pte_alloc */
3518
3519 spin_lock(&mm->page_table_lock);
3520 if (pgd_present(*pgd)) /* Another has populated it */
3521 pud_free(mm, new);
3522 else
3523 pgd_populate(mm, pgd, new);
3524 spin_unlock(&mm->page_table_lock);
3525 return 0;
3526}
3527#endif /* __PAGETABLE_PUD_FOLDED */
3528
3529#ifndef __PAGETABLE_PMD_FOLDED
3530/*
3531 * Allocate page middle directory.
3532 * We've already handled the fast-path in-line.
3533 */
3534int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3535{
3536 pmd_t *new = pmd_alloc_one(mm, address);
3537 if (!new)
3538 return -ENOMEM;
3539
3540 smp_wmb(); /* See comment in __pte_alloc */
3541
3542 spin_lock(&mm->page_table_lock);
3543#ifndef __ARCH_HAS_4LEVEL_HACK
3544 if (pud_present(*pud)) /* Another has populated it */
3545 pmd_free(mm, new);
3546 else
3547 pud_populate(mm, pud, new);
3548#else
3549 if (pgd_present(*pud)) /* Another has populated it */
3550 pmd_free(mm, new);
3551 else
3552 pgd_populate(mm, pud, new);
3553#endif /* __ARCH_HAS_4LEVEL_HACK */
3554 spin_unlock(&mm->page_table_lock);
3555 return 0;
3556}
3557#endif /* __PAGETABLE_PMD_FOLDED */
3558
3559int make_pages_present(unsigned long addr, unsigned long end)
3560{
3561 int ret, len, write;
3562 struct vm_area_struct * vma;
3563
3564 vma = find_vma(current->mm, addr);
3565 if (!vma)
3566 return -ENOMEM;
3567 /*
3568 * We want to touch writable mappings with a write fault in order
3569 * to break COW, except for shared mappings because these don't COW
3570 * and we would not want to dirty them for nothing.
3571 */
3572 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3573 BUG_ON(addr >= end);
3574 BUG_ON(end > vma->vm_end);
3575 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3576 ret = get_user_pages(current, current->mm, addr,
3577 len, write, 0, NULL, NULL);
3578 if (ret < 0)
3579 return ret;
3580 return ret == len ? 0 : -EFAULT;
3581}
3582
3583#if !defined(__HAVE_ARCH_GATE_AREA)
3584
3585#if defined(AT_SYSINFO_EHDR)
3586static struct vm_area_struct gate_vma;
3587
3588static int __init gate_vma_init(void)
3589{
3590 gate_vma.vm_mm = NULL;
3591 gate_vma.vm_start = FIXADDR_USER_START;
3592 gate_vma.vm_end = FIXADDR_USER_END;
3593 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3594 gate_vma.vm_page_prot = __P101;
3595 /*
3596 * Make sure the vDSO gets into every core dump.
3597 * Dumping its contents makes post-mortem fully interpretable later
3598 * without matching up the same kernel and hardware config to see
3599 * what PC values meant.
3600 */
3601 gate_vma.vm_flags |= VM_ALWAYSDUMP;
3602 return 0;
3603}
3604__initcall(gate_vma_init);
3605#endif
3606
3607struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3608{
3609#ifdef AT_SYSINFO_EHDR
3610 return &gate_vma;
3611#else
3612 return NULL;
3613#endif
3614}
3615
3616int in_gate_area_no_mm(unsigned long addr)
3617{
3618#ifdef AT_SYSINFO_EHDR
3619 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3620 return 1;
3621#endif
3622 return 0;
3623}
3624
3625#endif /* __HAVE_ARCH_GATE_AREA */
3626
3627static int __follow_pte(struct mm_struct *mm, unsigned long address,
3628 pte_t **ptepp, spinlock_t **ptlp)
3629{
3630 pgd_t *pgd;
3631 pud_t *pud;
3632 pmd_t *pmd;
3633 pte_t *ptep;
3634
3635 pgd = pgd_offset(mm, address);
3636 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3637 goto out;
3638
3639 pud = pud_offset(pgd, address);
3640 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3641 goto out;
3642
3643 pmd = pmd_offset(pud, address);
3644 VM_BUG_ON(pmd_trans_huge(*pmd));
3645 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3646 goto out;
3647
3648 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3649 if (pmd_huge(*pmd))
3650 goto out;
3651
3652 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3653 if (!ptep)
3654 goto out;
3655 if (!pte_present(*ptep))
3656 goto unlock;
3657 *ptepp = ptep;
3658 return 0;
3659unlock:
3660 pte_unmap_unlock(ptep, *ptlp);
3661out:
3662 return -EINVAL;
3663}
3664
3665static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3666 pte_t **ptepp, spinlock_t **ptlp)
3667{
3668 int res;
3669
3670 /* (void) is needed to make gcc happy */
3671 (void) __cond_lock(*ptlp,
3672 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3673 return res;
3674}
3675
3676/**
3677 * follow_pfn - look up PFN at a user virtual address
3678 * @vma: memory mapping
3679 * @address: user virtual address
3680 * @pfn: location to store found PFN
3681 *
3682 * Only IO mappings and raw PFN mappings are allowed.
3683 *
3684 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3685 */
3686int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3687 unsigned long *pfn)
3688{
3689 int ret = -EINVAL;
3690 spinlock_t *ptl;
3691 pte_t *ptep;
3692
3693 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3694 return ret;
3695
3696 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3697 if (ret)
3698 return ret;
3699 *pfn = pte_pfn(*ptep);
3700 pte_unmap_unlock(ptep, ptl);
3701 return 0;
3702}
3703EXPORT_SYMBOL(follow_pfn);
3704
3705#ifdef CONFIG_HAVE_IOREMAP_PROT
3706int follow_phys(struct vm_area_struct *vma,
3707 unsigned long address, unsigned int flags,
3708 unsigned long *prot, resource_size_t *phys)
3709{
3710 int ret = -EINVAL;
3711 pte_t *ptep, pte;
3712 spinlock_t *ptl;
3713
3714 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3715 goto out;
3716
3717 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3718 goto out;
3719 pte = *ptep;
3720
3721 if ((flags & FOLL_WRITE) && !pte_write(pte))
3722 goto unlock;
3723
3724 *prot = pgprot_val(pte_pgprot(pte));
3725 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3726
3727 ret = 0;
3728unlock:
3729 pte_unmap_unlock(ptep, ptl);
3730out:
3731 return ret;
3732}
3733
3734int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3735 void *buf, int len, int write)
3736{
3737 resource_size_t phys_addr;
3738 unsigned long prot = 0;
3739 void __iomem *maddr;
3740 int offset = addr & (PAGE_SIZE-1);
3741
3742 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3743 return -EINVAL;
3744
3745 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3746 if (write)
3747 memcpy_toio(maddr + offset, buf, len);
3748 else
3749 memcpy_fromio(buf, maddr + offset, len);
3750 iounmap(maddr);
3751
3752 return len;
3753}
3754#endif
3755
3756/*
3757 * Access another process' address space as given in mm. If non-NULL, use the
3758 * given task for page fault accounting.
3759 */
3760static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3761 unsigned long addr, void *buf, int len, int write)
3762{
3763 struct vm_area_struct *vma;
3764 void *old_buf = buf;
3765
3766 down_read(&mm->mmap_sem);
3767 /* ignore errors, just check how much was successfully transferred */
3768 while (len) {
3769 int bytes, ret, offset;
3770 void *maddr;
3771 struct page *page = NULL;
3772
3773 ret = get_user_pages(tsk, mm, addr, 1,
3774 write, 1, &page, &vma);
3775 if (ret <= 0) {
3776 /*
3777 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3778 * we can access using slightly different code.
3779 */
3780#ifdef CONFIG_HAVE_IOREMAP_PROT
3781 vma = find_vma(mm, addr);
3782 if (!vma || vma->vm_start > addr)
3783 break;
3784 if (vma->vm_ops && vma->vm_ops->access)
3785 ret = vma->vm_ops->access(vma, addr, buf,
3786 len, write);
3787 if (ret <= 0)
3788#endif
3789 break;
3790 bytes = ret;
3791 } else {
3792 bytes = len;
3793 offset = addr & (PAGE_SIZE-1);
3794 if (bytes > PAGE_SIZE-offset)
3795 bytes = PAGE_SIZE-offset;
3796
3797 maddr = kmap(page);
3798 if (write) {
3799 copy_to_user_page(vma, page, addr,
3800 maddr + offset, buf, bytes);
3801 set_page_dirty_lock(page);
3802 } else {
3803 copy_from_user_page(vma, page, addr,
3804 buf, maddr + offset, bytes);
3805 }
3806 kunmap(page);
3807 page_cache_release(page);
3808 }
3809 len -= bytes;
3810 buf += bytes;
3811 addr += bytes;
3812 }
3813 up_read(&mm->mmap_sem);
3814
3815 return buf - old_buf;
3816}
3817
3818/**
3819 * access_remote_vm - access another process' address space
3820 * @mm: the mm_struct of the target address space
3821 * @addr: start address to access
3822 * @buf: source or destination buffer
3823 * @len: number of bytes to transfer
3824 * @write: whether the access is a write
3825 *
3826 * The caller must hold a reference on @mm.
3827 */
3828int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3829 void *buf, int len, int write)
3830{
3831 return __access_remote_vm(NULL, mm, addr, buf, len, write);
3832}
3833
3834/*
3835 * Access another process' address space.
3836 * Source/target buffer must be kernel space,
3837 * Do not walk the page table directly, use get_user_pages
3838 */
3839int access_process_vm(struct task_struct *tsk, unsigned long addr,
3840 void *buf, int len, int write)
3841{
3842 struct mm_struct *mm;
3843 int ret;
3844
3845 mm = get_task_mm(tsk);
3846 if (!mm)
3847 return 0;
3848
3849 ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3850 mmput(mm);
3851
3852 return ret;
3853}
3854
3855/*
3856 * Print the name of a VMA.
3857 */
3858void print_vma_addr(char *prefix, unsigned long ip)
3859{
3860 struct mm_struct *mm = current->mm;
3861 struct vm_area_struct *vma;
3862
3863 /*
3864 * Do not print if we are in atomic
3865 * contexts (in exception stacks, etc.):
3866 */
3867 if (preempt_count())
3868 return;
3869
3870 down_read(&mm->mmap_sem);
3871 vma = find_vma(mm, ip);
3872 if (vma && vma->vm_file) {
3873 struct file *f = vma->vm_file;
3874 char *buf = (char *)__get_free_page(GFP_KERNEL);
3875 if (buf) {
3876 char *p, *s;
3877
3878 p = d_path(&f->f_path, buf, PAGE_SIZE);
3879 if (IS_ERR(p))
3880 p = "?";
3881 s = strrchr(p, '/');
3882 if (s)
3883 p = s+1;
3884 printk("%s%s[%lx+%lx]", prefix, p,
3885 vma->vm_start,
3886 vma->vm_end - vma->vm_start);
3887 free_page((unsigned long)buf);
3888 }
3889 }
3890 up_read(¤t->mm->mmap_sem);
3891}
3892
3893#ifdef CONFIG_PROVE_LOCKING
3894void might_fault(void)
3895{
3896 /*
3897 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3898 * holding the mmap_sem, this is safe because kernel memory doesn't
3899 * get paged out, therefore we'll never actually fault, and the
3900 * below annotations will generate false positives.
3901 */
3902 if (segment_eq(get_fs(), KERNEL_DS))
3903 return;
3904
3905 might_sleep();
3906 /*
3907 * it would be nicer only to annotate paths which are not under
3908 * pagefault_disable, however that requires a larger audit and
3909 * providing helpers like get_user_atomic.
3910 */
3911 if (!in_atomic() && current->mm)
3912 might_lock_read(¤t->mm->mmap_sem);
3913}
3914EXPORT_SYMBOL(might_fault);
3915#endif
3916
3917#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3918static void clear_gigantic_page(struct page *page,
3919 unsigned long addr,
3920 unsigned int pages_per_huge_page)
3921{
3922 int i;
3923 struct page *p = page;
3924
3925 might_sleep();
3926 for (i = 0; i < pages_per_huge_page;
3927 i++, p = mem_map_next(p, page, i)) {
3928 cond_resched();
3929 clear_user_highpage(p, addr + i * PAGE_SIZE);
3930 }
3931}
3932void clear_huge_page(struct page *page,
3933 unsigned long addr, unsigned int pages_per_huge_page)
3934{
3935 int i;
3936
3937 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3938 clear_gigantic_page(page, addr, pages_per_huge_page);
3939 return;
3940 }
3941
3942 might_sleep();
3943 for (i = 0; i < pages_per_huge_page; i++) {
3944 cond_resched();
3945 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3946 }
3947}
3948
3949static void copy_user_gigantic_page(struct page *dst, struct page *src,
3950 unsigned long addr,
3951 struct vm_area_struct *vma,
3952 unsigned int pages_per_huge_page)
3953{
3954 int i;
3955 struct page *dst_base = dst;
3956 struct page *src_base = src;
3957
3958 for (i = 0; i < pages_per_huge_page; ) {
3959 cond_resched();
3960 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3961
3962 i++;
3963 dst = mem_map_next(dst, dst_base, i);
3964 src = mem_map_next(src, src_base, i);
3965 }
3966}
3967
3968void copy_user_huge_page(struct page *dst, struct page *src,
3969 unsigned long addr, struct vm_area_struct *vma,
3970 unsigned int pages_per_huge_page)
3971{
3972 int i;
3973
3974 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3975 copy_user_gigantic_page(dst, src, addr, vma,
3976 pages_per_huge_page);
3977 return;
3978 }
3979
3980 might_sleep();
3981 for (i = 0; i < pages_per_huge_page; i++) {
3982 cond_resched();
3983 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3984 }
3985}
3986#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */