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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/memory.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 */
7
8/*
9 * demand-loading started 01.12.91 - seems it is high on the list of
10 * things wanted, and it should be easy to implement. - Linus
11 */
12
13/*
14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 * pages started 02.12.91, seems to work. - Linus.
16 *
17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 * would have taken more than the 6M I have free, but it worked well as
19 * far as I could see.
20 *
21 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22 */
23
24/*
25 * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 * thought has to go into this. Oh, well..
27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 * Found it. Everything seems to work now.
29 * 20.12.91 - Ok, making the swap-device changeable like the root.
30 */
31
32/*
33 * 05.04.94 - Multi-page memory management added for v1.1.
34 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 *
36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 * (Gerhard.Wichert@pdb.siemens.de)
38 *
39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40 */
41
42#include <linux/kernel_stat.h>
43#include <linux/mm.h>
44#include <linux/sched/mm.h>
45#include <linux/sched/coredump.h>
46#include <linux/sched/numa_balancing.h>
47#include <linux/sched/task.h>
48#include <linux/hugetlb.h>
49#include <linux/mman.h>
50#include <linux/swap.h>
51#include <linux/highmem.h>
52#include <linux/pagemap.h>
53#include <linux/memremap.h>
54#include <linux/ksm.h>
55#include <linux/rmap.h>
56#include <linux/export.h>
57#include <linux/delayacct.h>
58#include <linux/init.h>
59#include <linux/pfn_t.h>
60#include <linux/writeback.h>
61#include <linux/memcontrol.h>
62#include <linux/mmu_notifier.h>
63#include <linux/swapops.h>
64#include <linux/elf.h>
65#include <linux/gfp.h>
66#include <linux/migrate.h>
67#include <linux/string.h>
68#include <linux/dma-debug.h>
69#include <linux/debugfs.h>
70#include <linux/userfaultfd_k.h>
71#include <linux/dax.h>
72#include <linux/oom.h>
73#include <linux/numa.h>
74
75#include <asm/io.h>
76#include <asm/mmu_context.h>
77#include <asm/pgalloc.h>
78#include <linux/uaccess.h>
79#include <asm/tlb.h>
80#include <asm/tlbflush.h>
81#include <asm/pgtable.h>
82
83#include "internal.h"
84
85#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
86#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
87#endif
88
89#ifndef CONFIG_NEED_MULTIPLE_NODES
90/* use the per-pgdat data instead for discontigmem - mbligh */
91unsigned long max_mapnr;
92EXPORT_SYMBOL(max_mapnr);
93
94struct page *mem_map;
95EXPORT_SYMBOL(mem_map);
96#endif
97
98/*
99 * A number of key systems in x86 including ioremap() rely on the assumption
100 * that high_memory defines the upper bound on direct map memory, then end
101 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
102 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
103 * and ZONE_HIGHMEM.
104 */
105void *high_memory;
106EXPORT_SYMBOL(high_memory);
107
108/*
109 * Randomize the address space (stacks, mmaps, brk, etc.).
110 *
111 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
112 * as ancient (libc5 based) binaries can segfault. )
113 */
114int randomize_va_space __read_mostly =
115#ifdef CONFIG_COMPAT_BRK
116 1;
117#else
118 2;
119#endif
120
121static int __init disable_randmaps(char *s)
122{
123 randomize_va_space = 0;
124 return 1;
125}
126__setup("norandmaps", disable_randmaps);
127
128unsigned long zero_pfn __read_mostly;
129EXPORT_SYMBOL(zero_pfn);
130
131unsigned long highest_memmap_pfn __read_mostly;
132
133/*
134 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
135 */
136static int __init init_zero_pfn(void)
137{
138 zero_pfn = page_to_pfn(ZERO_PAGE(0));
139 return 0;
140}
141core_initcall(init_zero_pfn);
142
143
144#if defined(SPLIT_RSS_COUNTING)
145
146void sync_mm_rss(struct mm_struct *mm)
147{
148 int i;
149
150 for (i = 0; i < NR_MM_COUNTERS; i++) {
151 if (current->rss_stat.count[i]) {
152 add_mm_counter(mm, i, current->rss_stat.count[i]);
153 current->rss_stat.count[i] = 0;
154 }
155 }
156 current->rss_stat.events = 0;
157}
158
159static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
160{
161 struct task_struct *task = current;
162
163 if (likely(task->mm == mm))
164 task->rss_stat.count[member] += val;
165 else
166 add_mm_counter(mm, member, val);
167}
168#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
169#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
170
171/* sync counter once per 64 page faults */
172#define TASK_RSS_EVENTS_THRESH (64)
173static void check_sync_rss_stat(struct task_struct *task)
174{
175 if (unlikely(task != current))
176 return;
177 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
178 sync_mm_rss(task->mm);
179}
180#else /* SPLIT_RSS_COUNTING */
181
182#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
183#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
184
185static void check_sync_rss_stat(struct task_struct *task)
186{
187}
188
189#endif /* SPLIT_RSS_COUNTING */
190
191/*
192 * Note: this doesn't free the actual pages themselves. That
193 * has been handled earlier when unmapping all the memory regions.
194 */
195static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
196 unsigned long addr)
197{
198 pgtable_t token = pmd_pgtable(*pmd);
199 pmd_clear(pmd);
200 pte_free_tlb(tlb, token, addr);
201 mm_dec_nr_ptes(tlb->mm);
202}
203
204static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
205 unsigned long addr, unsigned long end,
206 unsigned long floor, unsigned long ceiling)
207{
208 pmd_t *pmd;
209 unsigned long next;
210 unsigned long start;
211
212 start = addr;
213 pmd = pmd_offset(pud, addr);
214 do {
215 next = pmd_addr_end(addr, end);
216 if (pmd_none_or_clear_bad(pmd))
217 continue;
218 free_pte_range(tlb, pmd, addr);
219 } while (pmd++, addr = next, addr != end);
220
221 start &= PUD_MASK;
222 if (start < floor)
223 return;
224 if (ceiling) {
225 ceiling &= PUD_MASK;
226 if (!ceiling)
227 return;
228 }
229 if (end - 1 > ceiling - 1)
230 return;
231
232 pmd = pmd_offset(pud, start);
233 pud_clear(pud);
234 pmd_free_tlb(tlb, pmd, start);
235 mm_dec_nr_pmds(tlb->mm);
236}
237
238static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
239 unsigned long addr, unsigned long end,
240 unsigned long floor, unsigned long ceiling)
241{
242 pud_t *pud;
243 unsigned long next;
244 unsigned long start;
245
246 start = addr;
247 pud = pud_offset(p4d, addr);
248 do {
249 next = pud_addr_end(addr, end);
250 if (pud_none_or_clear_bad(pud))
251 continue;
252 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
253 } while (pud++, addr = next, addr != end);
254
255 start &= P4D_MASK;
256 if (start < floor)
257 return;
258 if (ceiling) {
259 ceiling &= P4D_MASK;
260 if (!ceiling)
261 return;
262 }
263 if (end - 1 > ceiling - 1)
264 return;
265
266 pud = pud_offset(p4d, start);
267 p4d_clear(p4d);
268 pud_free_tlb(tlb, pud, start);
269 mm_dec_nr_puds(tlb->mm);
270}
271
272static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
273 unsigned long addr, unsigned long end,
274 unsigned long floor, unsigned long ceiling)
275{
276 p4d_t *p4d;
277 unsigned long next;
278 unsigned long start;
279
280 start = addr;
281 p4d = p4d_offset(pgd, addr);
282 do {
283 next = p4d_addr_end(addr, end);
284 if (p4d_none_or_clear_bad(p4d))
285 continue;
286 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
287 } while (p4d++, addr = next, addr != end);
288
289 start &= PGDIR_MASK;
290 if (start < floor)
291 return;
292 if (ceiling) {
293 ceiling &= PGDIR_MASK;
294 if (!ceiling)
295 return;
296 }
297 if (end - 1 > ceiling - 1)
298 return;
299
300 p4d = p4d_offset(pgd, start);
301 pgd_clear(pgd);
302 p4d_free_tlb(tlb, p4d, start);
303}
304
305/*
306 * This function frees user-level page tables of a process.
307 */
308void free_pgd_range(struct mmu_gather *tlb,
309 unsigned long addr, unsigned long end,
310 unsigned long floor, unsigned long ceiling)
311{
312 pgd_t *pgd;
313 unsigned long next;
314
315 /*
316 * The next few lines have given us lots of grief...
317 *
318 * Why are we testing PMD* at this top level? Because often
319 * there will be no work to do at all, and we'd prefer not to
320 * go all the way down to the bottom just to discover that.
321 *
322 * Why all these "- 1"s? Because 0 represents both the bottom
323 * of the address space and the top of it (using -1 for the
324 * top wouldn't help much: the masks would do the wrong thing).
325 * The rule is that addr 0 and floor 0 refer to the bottom of
326 * the address space, but end 0 and ceiling 0 refer to the top
327 * Comparisons need to use "end - 1" and "ceiling - 1" (though
328 * that end 0 case should be mythical).
329 *
330 * Wherever addr is brought up or ceiling brought down, we must
331 * be careful to reject "the opposite 0" before it confuses the
332 * subsequent tests. But what about where end is brought down
333 * by PMD_SIZE below? no, end can't go down to 0 there.
334 *
335 * Whereas we round start (addr) and ceiling down, by different
336 * masks at different levels, in order to test whether a table
337 * now has no other vmas using it, so can be freed, we don't
338 * bother to round floor or end up - the tests don't need that.
339 */
340
341 addr &= PMD_MASK;
342 if (addr < floor) {
343 addr += PMD_SIZE;
344 if (!addr)
345 return;
346 }
347 if (ceiling) {
348 ceiling &= PMD_MASK;
349 if (!ceiling)
350 return;
351 }
352 if (end - 1 > ceiling - 1)
353 end -= PMD_SIZE;
354 if (addr > end - 1)
355 return;
356 /*
357 * We add page table cache pages with PAGE_SIZE,
358 * (see pte_free_tlb()), flush the tlb if we need
359 */
360 tlb_change_page_size(tlb, PAGE_SIZE);
361 pgd = pgd_offset(tlb->mm, addr);
362 do {
363 next = pgd_addr_end(addr, end);
364 if (pgd_none_or_clear_bad(pgd))
365 continue;
366 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
367 } while (pgd++, addr = next, addr != end);
368}
369
370void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
371 unsigned long floor, unsigned long ceiling)
372{
373 while (vma) {
374 struct vm_area_struct *next = vma->vm_next;
375 unsigned long addr = vma->vm_start;
376
377 /*
378 * Hide vma from rmap and truncate_pagecache before freeing
379 * pgtables
380 */
381 unlink_anon_vmas(vma);
382 unlink_file_vma(vma);
383
384 if (is_vm_hugetlb_page(vma)) {
385 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
386 floor, next ? next->vm_start : ceiling);
387 } else {
388 /*
389 * Optimization: gather nearby vmas into one call down
390 */
391 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
392 && !is_vm_hugetlb_page(next)) {
393 vma = next;
394 next = vma->vm_next;
395 unlink_anon_vmas(vma);
396 unlink_file_vma(vma);
397 }
398 free_pgd_range(tlb, addr, vma->vm_end,
399 floor, next ? next->vm_start : ceiling);
400 }
401 vma = next;
402 }
403}
404
405int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
406{
407 spinlock_t *ptl;
408 pgtable_t new = pte_alloc_one(mm);
409 if (!new)
410 return -ENOMEM;
411
412 /*
413 * Ensure all pte setup (eg. pte page lock and page clearing) are
414 * visible before the pte is made visible to other CPUs by being
415 * put into page tables.
416 *
417 * The other side of the story is the pointer chasing in the page
418 * table walking code (when walking the page table without locking;
419 * ie. most of the time). Fortunately, these data accesses consist
420 * of a chain of data-dependent loads, meaning most CPUs (alpha
421 * being the notable exception) will already guarantee loads are
422 * seen in-order. See the alpha page table accessors for the
423 * smp_read_barrier_depends() barriers in page table walking code.
424 */
425 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
426
427 ptl = pmd_lock(mm, pmd);
428 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
429 mm_inc_nr_ptes(mm);
430 pmd_populate(mm, pmd, new);
431 new = NULL;
432 }
433 spin_unlock(ptl);
434 if (new)
435 pte_free(mm, new);
436 return 0;
437}
438
439int __pte_alloc_kernel(pmd_t *pmd)
440{
441 pte_t *new = pte_alloc_one_kernel(&init_mm);
442 if (!new)
443 return -ENOMEM;
444
445 smp_wmb(); /* See comment in __pte_alloc */
446
447 spin_lock(&init_mm.page_table_lock);
448 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
449 pmd_populate_kernel(&init_mm, pmd, new);
450 new = NULL;
451 }
452 spin_unlock(&init_mm.page_table_lock);
453 if (new)
454 pte_free_kernel(&init_mm, new);
455 return 0;
456}
457
458static inline void init_rss_vec(int *rss)
459{
460 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
461}
462
463static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
464{
465 int i;
466
467 if (current->mm == mm)
468 sync_mm_rss(mm);
469 for (i = 0; i < NR_MM_COUNTERS; i++)
470 if (rss[i])
471 add_mm_counter(mm, i, rss[i]);
472}
473
474/*
475 * This function is called to print an error when a bad pte
476 * is found. For example, we might have a PFN-mapped pte in
477 * a region that doesn't allow it.
478 *
479 * The calling function must still handle the error.
480 */
481static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
482 pte_t pte, struct page *page)
483{
484 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
485 p4d_t *p4d = p4d_offset(pgd, addr);
486 pud_t *pud = pud_offset(p4d, addr);
487 pmd_t *pmd = pmd_offset(pud, addr);
488 struct address_space *mapping;
489 pgoff_t index;
490 static unsigned long resume;
491 static unsigned long nr_shown;
492 static unsigned long nr_unshown;
493
494 /*
495 * Allow a burst of 60 reports, then keep quiet for that minute;
496 * or allow a steady drip of one report per second.
497 */
498 if (nr_shown == 60) {
499 if (time_before(jiffies, resume)) {
500 nr_unshown++;
501 return;
502 }
503 if (nr_unshown) {
504 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
505 nr_unshown);
506 nr_unshown = 0;
507 }
508 nr_shown = 0;
509 }
510 if (nr_shown++ == 0)
511 resume = jiffies + 60 * HZ;
512
513 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
514 index = linear_page_index(vma, addr);
515
516 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
517 current->comm,
518 (long long)pte_val(pte), (long long)pmd_val(*pmd));
519 if (page)
520 dump_page(page, "bad pte");
521 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
522 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
523 pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
524 vma->vm_file,
525 vma->vm_ops ? vma->vm_ops->fault : NULL,
526 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
527 mapping ? mapping->a_ops->readpage : NULL);
528 dump_stack();
529 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
530}
531
532/*
533 * vm_normal_page -- This function gets the "struct page" associated with a pte.
534 *
535 * "Special" mappings do not wish to be associated with a "struct page" (either
536 * it doesn't exist, or it exists but they don't want to touch it). In this
537 * case, NULL is returned here. "Normal" mappings do have a struct page.
538 *
539 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
540 * pte bit, in which case this function is trivial. Secondly, an architecture
541 * may not have a spare pte bit, which requires a more complicated scheme,
542 * described below.
543 *
544 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
545 * special mapping (even if there are underlying and valid "struct pages").
546 * COWed pages of a VM_PFNMAP are always normal.
547 *
548 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
549 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
550 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
551 * mapping will always honor the rule
552 *
553 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
554 *
555 * And for normal mappings this is false.
556 *
557 * This restricts such mappings to be a linear translation from virtual address
558 * to pfn. To get around this restriction, we allow arbitrary mappings so long
559 * as the vma is not a COW mapping; in that case, we know that all ptes are
560 * special (because none can have been COWed).
561 *
562 *
563 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
564 *
565 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
566 * page" backing, however the difference is that _all_ pages with a struct
567 * page (that is, those where pfn_valid is true) are refcounted and considered
568 * normal pages by the VM. The disadvantage is that pages are refcounted
569 * (which can be slower and simply not an option for some PFNMAP users). The
570 * advantage is that we don't have to follow the strict linearity rule of
571 * PFNMAP mappings in order to support COWable mappings.
572 *
573 */
574struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
575 pte_t pte)
576{
577 unsigned long pfn = pte_pfn(pte);
578
579 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
580 if (likely(!pte_special(pte)))
581 goto check_pfn;
582 if (vma->vm_ops && vma->vm_ops->find_special_page)
583 return vma->vm_ops->find_special_page(vma, addr);
584 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
585 return NULL;
586 if (is_zero_pfn(pfn))
587 return NULL;
588 if (pte_devmap(pte))
589 return NULL;
590
591 print_bad_pte(vma, addr, pte, NULL);
592 return NULL;
593 }
594
595 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
596
597 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
598 if (vma->vm_flags & VM_MIXEDMAP) {
599 if (!pfn_valid(pfn))
600 return NULL;
601 goto out;
602 } else {
603 unsigned long off;
604 off = (addr - vma->vm_start) >> PAGE_SHIFT;
605 if (pfn == vma->vm_pgoff + off)
606 return NULL;
607 if (!is_cow_mapping(vma->vm_flags))
608 return NULL;
609 }
610 }
611
612 if (is_zero_pfn(pfn))
613 return NULL;
614
615check_pfn:
616 if (unlikely(pfn > highest_memmap_pfn)) {
617 print_bad_pte(vma, addr, pte, NULL);
618 return NULL;
619 }
620
621 /*
622 * NOTE! We still have PageReserved() pages in the page tables.
623 * eg. VDSO mappings can cause them to exist.
624 */
625out:
626 return pfn_to_page(pfn);
627}
628
629#ifdef CONFIG_TRANSPARENT_HUGEPAGE
630struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
631 pmd_t pmd)
632{
633 unsigned long pfn = pmd_pfn(pmd);
634
635 /*
636 * There is no pmd_special() but there may be special pmds, e.g.
637 * in a direct-access (dax) mapping, so let's just replicate the
638 * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
639 */
640 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
641 if (vma->vm_flags & VM_MIXEDMAP) {
642 if (!pfn_valid(pfn))
643 return NULL;
644 goto out;
645 } else {
646 unsigned long off;
647 off = (addr - vma->vm_start) >> PAGE_SHIFT;
648 if (pfn == vma->vm_pgoff + off)
649 return NULL;
650 if (!is_cow_mapping(vma->vm_flags))
651 return NULL;
652 }
653 }
654
655 if (pmd_devmap(pmd))
656 return NULL;
657 if (is_zero_pfn(pfn))
658 return NULL;
659 if (unlikely(pfn > highest_memmap_pfn))
660 return NULL;
661
662 /*
663 * NOTE! We still have PageReserved() pages in the page tables.
664 * eg. VDSO mappings can cause them to exist.
665 */
666out:
667 return pfn_to_page(pfn);
668}
669#endif
670
671/*
672 * copy one vm_area from one task to the other. Assumes the page tables
673 * already present in the new task to be cleared in the whole range
674 * covered by this vma.
675 */
676
677static inline unsigned long
678copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
679 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
680 unsigned long addr, int *rss)
681{
682 unsigned long vm_flags = vma->vm_flags;
683 pte_t pte = *src_pte;
684 struct page *page;
685
686 /* pte contains position in swap or file, so copy. */
687 if (unlikely(!pte_present(pte))) {
688 swp_entry_t entry = pte_to_swp_entry(pte);
689
690 if (likely(!non_swap_entry(entry))) {
691 if (swap_duplicate(entry) < 0)
692 return entry.val;
693
694 /* make sure dst_mm is on swapoff's mmlist. */
695 if (unlikely(list_empty(&dst_mm->mmlist))) {
696 spin_lock(&mmlist_lock);
697 if (list_empty(&dst_mm->mmlist))
698 list_add(&dst_mm->mmlist,
699 &src_mm->mmlist);
700 spin_unlock(&mmlist_lock);
701 }
702 rss[MM_SWAPENTS]++;
703 } else if (is_migration_entry(entry)) {
704 page = migration_entry_to_page(entry);
705
706 rss[mm_counter(page)]++;
707
708 if (is_write_migration_entry(entry) &&
709 is_cow_mapping(vm_flags)) {
710 /*
711 * COW mappings require pages in both
712 * parent and child to be set to read.
713 */
714 make_migration_entry_read(&entry);
715 pte = swp_entry_to_pte(entry);
716 if (pte_swp_soft_dirty(*src_pte))
717 pte = pte_swp_mksoft_dirty(pte);
718 set_pte_at(src_mm, addr, src_pte, pte);
719 }
720 } else if (is_device_private_entry(entry)) {
721 page = device_private_entry_to_page(entry);
722
723 /*
724 * Update rss count even for unaddressable pages, as
725 * they should treated just like normal pages in this
726 * respect.
727 *
728 * We will likely want to have some new rss counters
729 * for unaddressable pages, at some point. But for now
730 * keep things as they are.
731 */
732 get_page(page);
733 rss[mm_counter(page)]++;
734 page_dup_rmap(page, false);
735
736 /*
737 * We do not preserve soft-dirty information, because so
738 * far, checkpoint/restore is the only feature that
739 * requires that. And checkpoint/restore does not work
740 * when a device driver is involved (you cannot easily
741 * save and restore device driver state).
742 */
743 if (is_write_device_private_entry(entry) &&
744 is_cow_mapping(vm_flags)) {
745 make_device_private_entry_read(&entry);
746 pte = swp_entry_to_pte(entry);
747 set_pte_at(src_mm, addr, src_pte, pte);
748 }
749 }
750 goto out_set_pte;
751 }
752
753 /*
754 * If it's a COW mapping, write protect it both
755 * in the parent and the child
756 */
757 if (is_cow_mapping(vm_flags) && pte_write(pte)) {
758 ptep_set_wrprotect(src_mm, addr, src_pte);
759 pte = pte_wrprotect(pte);
760 }
761
762 /*
763 * If it's a shared mapping, mark it clean in
764 * the child
765 */
766 if (vm_flags & VM_SHARED)
767 pte = pte_mkclean(pte);
768 pte = pte_mkold(pte);
769
770 page = vm_normal_page(vma, addr, pte);
771 if (page) {
772 get_page(page);
773 page_dup_rmap(page, false);
774 rss[mm_counter(page)]++;
775 } else if (pte_devmap(pte)) {
776 page = pte_page(pte);
777 }
778
779out_set_pte:
780 set_pte_at(dst_mm, addr, dst_pte, pte);
781 return 0;
782}
783
784static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
785 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
786 unsigned long addr, unsigned long end)
787{
788 pte_t *orig_src_pte, *orig_dst_pte;
789 pte_t *src_pte, *dst_pte;
790 spinlock_t *src_ptl, *dst_ptl;
791 int progress = 0;
792 int rss[NR_MM_COUNTERS];
793 swp_entry_t entry = (swp_entry_t){0};
794
795again:
796 init_rss_vec(rss);
797
798 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
799 if (!dst_pte)
800 return -ENOMEM;
801 src_pte = pte_offset_map(src_pmd, addr);
802 src_ptl = pte_lockptr(src_mm, src_pmd);
803 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
804 orig_src_pte = src_pte;
805 orig_dst_pte = dst_pte;
806 arch_enter_lazy_mmu_mode();
807
808 do {
809 /*
810 * We are holding two locks at this point - either of them
811 * could generate latencies in another task on another CPU.
812 */
813 if (progress >= 32) {
814 progress = 0;
815 if (need_resched() ||
816 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
817 break;
818 }
819 if (pte_none(*src_pte)) {
820 progress++;
821 continue;
822 }
823 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
824 vma, addr, rss);
825 if (entry.val)
826 break;
827 progress += 8;
828 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
829
830 arch_leave_lazy_mmu_mode();
831 spin_unlock(src_ptl);
832 pte_unmap(orig_src_pte);
833 add_mm_rss_vec(dst_mm, rss);
834 pte_unmap_unlock(orig_dst_pte, dst_ptl);
835 cond_resched();
836
837 if (entry.val) {
838 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
839 return -ENOMEM;
840 progress = 0;
841 }
842 if (addr != end)
843 goto again;
844 return 0;
845}
846
847static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
848 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
849 unsigned long addr, unsigned long end)
850{
851 pmd_t *src_pmd, *dst_pmd;
852 unsigned long next;
853
854 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
855 if (!dst_pmd)
856 return -ENOMEM;
857 src_pmd = pmd_offset(src_pud, addr);
858 do {
859 next = pmd_addr_end(addr, end);
860 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
861 || pmd_devmap(*src_pmd)) {
862 int err;
863 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
864 err = copy_huge_pmd(dst_mm, src_mm,
865 dst_pmd, src_pmd, addr, vma);
866 if (err == -ENOMEM)
867 return -ENOMEM;
868 if (!err)
869 continue;
870 /* fall through */
871 }
872 if (pmd_none_or_clear_bad(src_pmd))
873 continue;
874 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
875 vma, addr, next))
876 return -ENOMEM;
877 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
878 return 0;
879}
880
881static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
882 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
883 unsigned long addr, unsigned long end)
884{
885 pud_t *src_pud, *dst_pud;
886 unsigned long next;
887
888 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
889 if (!dst_pud)
890 return -ENOMEM;
891 src_pud = pud_offset(src_p4d, addr);
892 do {
893 next = pud_addr_end(addr, end);
894 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
895 int err;
896
897 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
898 err = copy_huge_pud(dst_mm, src_mm,
899 dst_pud, src_pud, addr, vma);
900 if (err == -ENOMEM)
901 return -ENOMEM;
902 if (!err)
903 continue;
904 /* fall through */
905 }
906 if (pud_none_or_clear_bad(src_pud))
907 continue;
908 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
909 vma, addr, next))
910 return -ENOMEM;
911 } while (dst_pud++, src_pud++, addr = next, addr != end);
912 return 0;
913}
914
915static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
916 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
917 unsigned long addr, unsigned long end)
918{
919 p4d_t *src_p4d, *dst_p4d;
920 unsigned long next;
921
922 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
923 if (!dst_p4d)
924 return -ENOMEM;
925 src_p4d = p4d_offset(src_pgd, addr);
926 do {
927 next = p4d_addr_end(addr, end);
928 if (p4d_none_or_clear_bad(src_p4d))
929 continue;
930 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
931 vma, addr, next))
932 return -ENOMEM;
933 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
934 return 0;
935}
936
937int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
938 struct vm_area_struct *vma)
939{
940 pgd_t *src_pgd, *dst_pgd;
941 unsigned long next;
942 unsigned long addr = vma->vm_start;
943 unsigned long end = vma->vm_end;
944 struct mmu_notifier_range range;
945 bool is_cow;
946 int ret;
947
948 /*
949 * Don't copy ptes where a page fault will fill them correctly.
950 * Fork becomes much lighter when there are big shared or private
951 * readonly mappings. The tradeoff is that copy_page_range is more
952 * efficient than faulting.
953 */
954 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
955 !vma->anon_vma)
956 return 0;
957
958 if (is_vm_hugetlb_page(vma))
959 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
960
961 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
962 /*
963 * We do not free on error cases below as remove_vma
964 * gets called on error from higher level routine
965 */
966 ret = track_pfn_copy(vma);
967 if (ret)
968 return ret;
969 }
970
971 /*
972 * We need to invalidate the secondary MMU mappings only when
973 * there could be a permission downgrade on the ptes of the
974 * parent mm. And a permission downgrade will only happen if
975 * is_cow_mapping() returns true.
976 */
977 is_cow = is_cow_mapping(vma->vm_flags);
978
979 if (is_cow) {
980 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
981 0, vma, src_mm, addr, end);
982 mmu_notifier_invalidate_range_start(&range);
983 }
984
985 ret = 0;
986 dst_pgd = pgd_offset(dst_mm, addr);
987 src_pgd = pgd_offset(src_mm, addr);
988 do {
989 next = pgd_addr_end(addr, end);
990 if (pgd_none_or_clear_bad(src_pgd))
991 continue;
992 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
993 vma, addr, next))) {
994 ret = -ENOMEM;
995 break;
996 }
997 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
998
999 if (is_cow)
1000 mmu_notifier_invalidate_range_end(&range);
1001 return ret;
1002}
1003
1004static unsigned long zap_pte_range(struct mmu_gather *tlb,
1005 struct vm_area_struct *vma, pmd_t *pmd,
1006 unsigned long addr, unsigned long end,
1007 struct zap_details *details)
1008{
1009 struct mm_struct *mm = tlb->mm;
1010 int force_flush = 0;
1011 int rss[NR_MM_COUNTERS];
1012 spinlock_t *ptl;
1013 pte_t *start_pte;
1014 pte_t *pte;
1015 swp_entry_t entry;
1016
1017 tlb_change_page_size(tlb, PAGE_SIZE);
1018again:
1019 init_rss_vec(rss);
1020 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1021 pte = start_pte;
1022 flush_tlb_batched_pending(mm);
1023 arch_enter_lazy_mmu_mode();
1024 do {
1025 pte_t ptent = *pte;
1026 if (pte_none(ptent))
1027 continue;
1028
1029 if (need_resched())
1030 break;
1031
1032 if (pte_present(ptent)) {
1033 struct page *page;
1034
1035 page = vm_normal_page(vma, addr, ptent);
1036 if (unlikely(details) && page) {
1037 /*
1038 * unmap_shared_mapping_pages() wants to
1039 * invalidate cache without truncating:
1040 * unmap shared but keep private pages.
1041 */
1042 if (details->check_mapping &&
1043 details->check_mapping != page_rmapping(page))
1044 continue;
1045 }
1046 ptent = ptep_get_and_clear_full(mm, addr, pte,
1047 tlb->fullmm);
1048 tlb_remove_tlb_entry(tlb, pte, addr);
1049 if (unlikely(!page))
1050 continue;
1051
1052 if (!PageAnon(page)) {
1053 if (pte_dirty(ptent)) {
1054 force_flush = 1;
1055 set_page_dirty(page);
1056 }
1057 if (pte_young(ptent) &&
1058 likely(!(vma->vm_flags & VM_SEQ_READ)))
1059 mark_page_accessed(page);
1060 }
1061 rss[mm_counter(page)]--;
1062 page_remove_rmap(page, false);
1063 if (unlikely(page_mapcount(page) < 0))
1064 print_bad_pte(vma, addr, ptent, page);
1065 if (unlikely(__tlb_remove_page(tlb, page))) {
1066 force_flush = 1;
1067 addr += PAGE_SIZE;
1068 break;
1069 }
1070 continue;
1071 }
1072
1073 entry = pte_to_swp_entry(ptent);
1074 if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1075 struct page *page = device_private_entry_to_page(entry);
1076
1077 if (unlikely(details && details->check_mapping)) {
1078 /*
1079 * unmap_shared_mapping_pages() wants to
1080 * invalidate cache without truncating:
1081 * unmap shared but keep private pages.
1082 */
1083 if (details->check_mapping !=
1084 page_rmapping(page))
1085 continue;
1086 }
1087
1088 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1089 rss[mm_counter(page)]--;
1090 page_remove_rmap(page, false);
1091 put_page(page);
1092 continue;
1093 }
1094
1095 /* If details->check_mapping, we leave swap entries. */
1096 if (unlikely(details))
1097 continue;
1098
1099 if (!non_swap_entry(entry))
1100 rss[MM_SWAPENTS]--;
1101 else if (is_migration_entry(entry)) {
1102 struct page *page;
1103
1104 page = migration_entry_to_page(entry);
1105 rss[mm_counter(page)]--;
1106 }
1107 if (unlikely(!free_swap_and_cache(entry)))
1108 print_bad_pte(vma, addr, ptent, NULL);
1109 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1110 } while (pte++, addr += PAGE_SIZE, addr != end);
1111
1112 add_mm_rss_vec(mm, rss);
1113 arch_leave_lazy_mmu_mode();
1114
1115 /* Do the actual TLB flush before dropping ptl */
1116 if (force_flush)
1117 tlb_flush_mmu_tlbonly(tlb);
1118 pte_unmap_unlock(start_pte, ptl);
1119
1120 /*
1121 * If we forced a TLB flush (either due to running out of
1122 * batch buffers or because we needed to flush dirty TLB
1123 * entries before releasing the ptl), free the batched
1124 * memory too. Restart if we didn't do everything.
1125 */
1126 if (force_flush) {
1127 force_flush = 0;
1128 tlb_flush_mmu(tlb);
1129 }
1130
1131 if (addr != end) {
1132 cond_resched();
1133 goto again;
1134 }
1135
1136 return addr;
1137}
1138
1139static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1140 struct vm_area_struct *vma, pud_t *pud,
1141 unsigned long addr, unsigned long end,
1142 struct zap_details *details)
1143{
1144 pmd_t *pmd;
1145 unsigned long next;
1146
1147 pmd = pmd_offset(pud, addr);
1148 do {
1149 next = pmd_addr_end(addr, end);
1150 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1151 if (next - addr != HPAGE_PMD_SIZE)
1152 __split_huge_pmd(vma, pmd, addr, false, NULL);
1153 else if (zap_huge_pmd(tlb, vma, pmd, addr))
1154 goto next;
1155 /* fall through */
1156 }
1157 /*
1158 * Here there can be other concurrent MADV_DONTNEED or
1159 * trans huge page faults running, and if the pmd is
1160 * none or trans huge it can change under us. This is
1161 * because MADV_DONTNEED holds the mmap_sem in read
1162 * mode.
1163 */
1164 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1165 goto next;
1166 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1167next:
1168 cond_resched();
1169 } while (pmd++, addr = next, addr != end);
1170
1171 return addr;
1172}
1173
1174static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1175 struct vm_area_struct *vma, p4d_t *p4d,
1176 unsigned long addr, unsigned long end,
1177 struct zap_details *details)
1178{
1179 pud_t *pud;
1180 unsigned long next;
1181
1182 pud = pud_offset(p4d, addr);
1183 do {
1184 next = pud_addr_end(addr, end);
1185 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1186 if (next - addr != HPAGE_PUD_SIZE) {
1187 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1188 split_huge_pud(vma, pud, addr);
1189 } else if (zap_huge_pud(tlb, vma, pud, addr))
1190 goto next;
1191 /* fall through */
1192 }
1193 if (pud_none_or_clear_bad(pud))
1194 continue;
1195 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1196next:
1197 cond_resched();
1198 } while (pud++, addr = next, addr != end);
1199
1200 return addr;
1201}
1202
1203static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1204 struct vm_area_struct *vma, pgd_t *pgd,
1205 unsigned long addr, unsigned long end,
1206 struct zap_details *details)
1207{
1208 p4d_t *p4d;
1209 unsigned long next;
1210
1211 p4d = p4d_offset(pgd, addr);
1212 do {
1213 next = p4d_addr_end(addr, end);
1214 if (p4d_none_or_clear_bad(p4d))
1215 continue;
1216 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1217 } while (p4d++, addr = next, addr != end);
1218
1219 return addr;
1220}
1221
1222void unmap_page_range(struct mmu_gather *tlb,
1223 struct vm_area_struct *vma,
1224 unsigned long addr, unsigned long end,
1225 struct zap_details *details)
1226{
1227 pgd_t *pgd;
1228 unsigned long next;
1229
1230 BUG_ON(addr >= end);
1231 tlb_start_vma(tlb, vma);
1232 pgd = pgd_offset(vma->vm_mm, addr);
1233 do {
1234 next = pgd_addr_end(addr, end);
1235 if (pgd_none_or_clear_bad(pgd))
1236 continue;
1237 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1238 } while (pgd++, addr = next, addr != end);
1239 tlb_end_vma(tlb, vma);
1240}
1241
1242
1243static void unmap_single_vma(struct mmu_gather *tlb,
1244 struct vm_area_struct *vma, unsigned long start_addr,
1245 unsigned long end_addr,
1246 struct zap_details *details)
1247{
1248 unsigned long start = max(vma->vm_start, start_addr);
1249 unsigned long end;
1250
1251 if (start >= vma->vm_end)
1252 return;
1253 end = min(vma->vm_end, end_addr);
1254 if (end <= vma->vm_start)
1255 return;
1256
1257 if (vma->vm_file)
1258 uprobe_munmap(vma, start, end);
1259
1260 if (unlikely(vma->vm_flags & VM_PFNMAP))
1261 untrack_pfn(vma, 0, 0);
1262
1263 if (start != end) {
1264 if (unlikely(is_vm_hugetlb_page(vma))) {
1265 /*
1266 * It is undesirable to test vma->vm_file as it
1267 * should be non-null for valid hugetlb area.
1268 * However, vm_file will be NULL in the error
1269 * cleanup path of mmap_region. When
1270 * hugetlbfs ->mmap method fails,
1271 * mmap_region() nullifies vma->vm_file
1272 * before calling this function to clean up.
1273 * Since no pte has actually been setup, it is
1274 * safe to do nothing in this case.
1275 */
1276 if (vma->vm_file) {
1277 i_mmap_lock_write(vma->vm_file->f_mapping);
1278 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1279 i_mmap_unlock_write(vma->vm_file->f_mapping);
1280 }
1281 } else
1282 unmap_page_range(tlb, vma, start, end, details);
1283 }
1284}
1285
1286/**
1287 * unmap_vmas - unmap a range of memory covered by a list of vma's
1288 * @tlb: address of the caller's struct mmu_gather
1289 * @vma: the starting vma
1290 * @start_addr: virtual address at which to start unmapping
1291 * @end_addr: virtual address at which to end unmapping
1292 *
1293 * Unmap all pages in the vma list.
1294 *
1295 * Only addresses between `start' and `end' will be unmapped.
1296 *
1297 * The VMA list must be sorted in ascending virtual address order.
1298 *
1299 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1300 * range after unmap_vmas() returns. So the only responsibility here is to
1301 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1302 * drops the lock and schedules.
1303 */
1304void unmap_vmas(struct mmu_gather *tlb,
1305 struct vm_area_struct *vma, unsigned long start_addr,
1306 unsigned long end_addr)
1307{
1308 struct mmu_notifier_range range;
1309
1310 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
1311 start_addr, end_addr);
1312 mmu_notifier_invalidate_range_start(&range);
1313 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1314 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1315 mmu_notifier_invalidate_range_end(&range);
1316}
1317
1318/**
1319 * zap_page_range - remove user pages in a given range
1320 * @vma: vm_area_struct holding the applicable pages
1321 * @start: starting address of pages to zap
1322 * @size: number of bytes to zap
1323 *
1324 * Caller must protect the VMA list
1325 */
1326void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1327 unsigned long size)
1328{
1329 struct mmu_notifier_range range;
1330 struct mmu_gather tlb;
1331
1332 lru_add_drain();
1333 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1334 start, start + size);
1335 tlb_gather_mmu(&tlb, vma->vm_mm, start, range.end);
1336 update_hiwater_rss(vma->vm_mm);
1337 mmu_notifier_invalidate_range_start(&range);
1338 for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
1339 unmap_single_vma(&tlb, vma, start, range.end, NULL);
1340 mmu_notifier_invalidate_range_end(&range);
1341 tlb_finish_mmu(&tlb, start, range.end);
1342}
1343
1344/**
1345 * zap_page_range_single - remove user pages in a given range
1346 * @vma: vm_area_struct holding the applicable pages
1347 * @address: starting address of pages to zap
1348 * @size: number of bytes to zap
1349 * @details: details of shared cache invalidation
1350 *
1351 * The range must fit into one VMA.
1352 */
1353static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1354 unsigned long size, struct zap_details *details)
1355{
1356 struct mmu_notifier_range range;
1357 struct mmu_gather tlb;
1358
1359 lru_add_drain();
1360 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1361 address, address + size);
1362 tlb_gather_mmu(&tlb, vma->vm_mm, address, range.end);
1363 update_hiwater_rss(vma->vm_mm);
1364 mmu_notifier_invalidate_range_start(&range);
1365 unmap_single_vma(&tlb, vma, address, range.end, details);
1366 mmu_notifier_invalidate_range_end(&range);
1367 tlb_finish_mmu(&tlb, address, range.end);
1368}
1369
1370/**
1371 * zap_vma_ptes - remove ptes mapping the vma
1372 * @vma: vm_area_struct holding ptes to be zapped
1373 * @address: starting address of pages to zap
1374 * @size: number of bytes to zap
1375 *
1376 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1377 *
1378 * The entire address range must be fully contained within the vma.
1379 *
1380 */
1381void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1382 unsigned long size)
1383{
1384 if (address < vma->vm_start || address + size > vma->vm_end ||
1385 !(vma->vm_flags & VM_PFNMAP))
1386 return;
1387
1388 zap_page_range_single(vma, address, size, NULL);
1389}
1390EXPORT_SYMBOL_GPL(zap_vma_ptes);
1391
1392pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1393 spinlock_t **ptl)
1394{
1395 pgd_t *pgd;
1396 p4d_t *p4d;
1397 pud_t *pud;
1398 pmd_t *pmd;
1399
1400 pgd = pgd_offset(mm, addr);
1401 p4d = p4d_alloc(mm, pgd, addr);
1402 if (!p4d)
1403 return NULL;
1404 pud = pud_alloc(mm, p4d, addr);
1405 if (!pud)
1406 return NULL;
1407 pmd = pmd_alloc(mm, pud, addr);
1408 if (!pmd)
1409 return NULL;
1410
1411 VM_BUG_ON(pmd_trans_huge(*pmd));
1412 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1413}
1414
1415/*
1416 * This is the old fallback for page remapping.
1417 *
1418 * For historical reasons, it only allows reserved pages. Only
1419 * old drivers should use this, and they needed to mark their
1420 * pages reserved for the old functions anyway.
1421 */
1422static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1423 struct page *page, pgprot_t prot)
1424{
1425 struct mm_struct *mm = vma->vm_mm;
1426 int retval;
1427 pte_t *pte;
1428 spinlock_t *ptl;
1429
1430 retval = -EINVAL;
1431 if (PageAnon(page) || PageSlab(page) || page_has_type(page))
1432 goto out;
1433 retval = -ENOMEM;
1434 flush_dcache_page(page);
1435 pte = get_locked_pte(mm, addr, &ptl);
1436 if (!pte)
1437 goto out;
1438 retval = -EBUSY;
1439 if (!pte_none(*pte))
1440 goto out_unlock;
1441
1442 /* Ok, finally just insert the thing.. */
1443 get_page(page);
1444 inc_mm_counter_fast(mm, mm_counter_file(page));
1445 page_add_file_rmap(page, false);
1446 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1447
1448 retval = 0;
1449out_unlock:
1450 pte_unmap_unlock(pte, ptl);
1451out:
1452 return retval;
1453}
1454
1455/**
1456 * vm_insert_page - insert single page into user vma
1457 * @vma: user vma to map to
1458 * @addr: target user address of this page
1459 * @page: source kernel page
1460 *
1461 * This allows drivers to insert individual pages they've allocated
1462 * into a user vma.
1463 *
1464 * The page has to be a nice clean _individual_ kernel allocation.
1465 * If you allocate a compound page, you need to have marked it as
1466 * such (__GFP_COMP), or manually just split the page up yourself
1467 * (see split_page()).
1468 *
1469 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1470 * took an arbitrary page protection parameter. This doesn't allow
1471 * that. Your vma protection will have to be set up correctly, which
1472 * means that if you want a shared writable mapping, you'd better
1473 * ask for a shared writable mapping!
1474 *
1475 * The page does not need to be reserved.
1476 *
1477 * Usually this function is called from f_op->mmap() handler
1478 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1479 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1480 * function from other places, for example from page-fault handler.
1481 *
1482 * Return: %0 on success, negative error code otherwise.
1483 */
1484int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1485 struct page *page)
1486{
1487 if (addr < vma->vm_start || addr >= vma->vm_end)
1488 return -EFAULT;
1489 if (!page_count(page))
1490 return -EINVAL;
1491 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1492 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1493 BUG_ON(vma->vm_flags & VM_PFNMAP);
1494 vma->vm_flags |= VM_MIXEDMAP;
1495 }
1496 return insert_page(vma, addr, page, vma->vm_page_prot);
1497}
1498EXPORT_SYMBOL(vm_insert_page);
1499
1500/*
1501 * __vm_map_pages - maps range of kernel pages into user vma
1502 * @vma: user vma to map to
1503 * @pages: pointer to array of source kernel pages
1504 * @num: number of pages in page array
1505 * @offset: user's requested vm_pgoff
1506 *
1507 * This allows drivers to map range of kernel pages into a user vma.
1508 *
1509 * Return: 0 on success and error code otherwise.
1510 */
1511static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1512 unsigned long num, unsigned long offset)
1513{
1514 unsigned long count = vma_pages(vma);
1515 unsigned long uaddr = vma->vm_start;
1516 int ret, i;
1517
1518 /* Fail if the user requested offset is beyond the end of the object */
1519 if (offset >= num)
1520 return -ENXIO;
1521
1522 /* Fail if the user requested size exceeds available object size */
1523 if (count > num - offset)
1524 return -ENXIO;
1525
1526 for (i = 0; i < count; i++) {
1527 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
1528 if (ret < 0)
1529 return ret;
1530 uaddr += PAGE_SIZE;
1531 }
1532
1533 return 0;
1534}
1535
1536/**
1537 * vm_map_pages - maps range of kernel pages starts with non zero offset
1538 * @vma: user vma to map to
1539 * @pages: pointer to array of source kernel pages
1540 * @num: number of pages in page array
1541 *
1542 * Maps an object consisting of @num pages, catering for the user's
1543 * requested vm_pgoff
1544 *
1545 * If we fail to insert any page into the vma, the function will return
1546 * immediately leaving any previously inserted pages present. Callers
1547 * from the mmap handler may immediately return the error as their caller
1548 * will destroy the vma, removing any successfully inserted pages. Other
1549 * callers should make their own arrangements for calling unmap_region().
1550 *
1551 * Context: Process context. Called by mmap handlers.
1552 * Return: 0 on success and error code otherwise.
1553 */
1554int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
1555 unsigned long num)
1556{
1557 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
1558}
1559EXPORT_SYMBOL(vm_map_pages);
1560
1561/**
1562 * vm_map_pages_zero - map range of kernel pages starts with zero offset
1563 * @vma: user vma to map to
1564 * @pages: pointer to array of source kernel pages
1565 * @num: number of pages in page array
1566 *
1567 * Similar to vm_map_pages(), except that it explicitly sets the offset
1568 * to 0. This function is intended for the drivers that did not consider
1569 * vm_pgoff.
1570 *
1571 * Context: Process context. Called by mmap handlers.
1572 * Return: 0 on success and error code otherwise.
1573 */
1574int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
1575 unsigned long num)
1576{
1577 return __vm_map_pages(vma, pages, num, 0);
1578}
1579EXPORT_SYMBOL(vm_map_pages_zero);
1580
1581static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1582 pfn_t pfn, pgprot_t prot, bool mkwrite)
1583{
1584 struct mm_struct *mm = vma->vm_mm;
1585 pte_t *pte, entry;
1586 spinlock_t *ptl;
1587
1588 pte = get_locked_pte(mm, addr, &ptl);
1589 if (!pte)
1590 return VM_FAULT_OOM;
1591 if (!pte_none(*pte)) {
1592 if (mkwrite) {
1593 /*
1594 * For read faults on private mappings the PFN passed
1595 * in may not match the PFN we have mapped if the
1596 * mapped PFN is a writeable COW page. In the mkwrite
1597 * case we are creating a writable PTE for a shared
1598 * mapping and we expect the PFNs to match. If they
1599 * don't match, we are likely racing with block
1600 * allocation and mapping invalidation so just skip the
1601 * update.
1602 */
1603 if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
1604 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
1605 goto out_unlock;
1606 }
1607 entry = pte_mkyoung(*pte);
1608 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1609 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
1610 update_mmu_cache(vma, addr, pte);
1611 }
1612 goto out_unlock;
1613 }
1614
1615 /* Ok, finally just insert the thing.. */
1616 if (pfn_t_devmap(pfn))
1617 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1618 else
1619 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1620
1621 if (mkwrite) {
1622 entry = pte_mkyoung(entry);
1623 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1624 }
1625
1626 set_pte_at(mm, addr, pte, entry);
1627 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1628
1629out_unlock:
1630 pte_unmap_unlock(pte, ptl);
1631 return VM_FAULT_NOPAGE;
1632}
1633
1634/**
1635 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1636 * @vma: user vma to map to
1637 * @addr: target user address of this page
1638 * @pfn: source kernel pfn
1639 * @pgprot: pgprot flags for the inserted page
1640 *
1641 * This is exactly like vmf_insert_pfn(), except that it allows drivers to
1642 * to override pgprot on a per-page basis.
1643 *
1644 * This only makes sense for IO mappings, and it makes no sense for
1645 * COW mappings. In general, using multiple vmas is preferable;
1646 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
1647 * impractical.
1648 *
1649 * Context: Process context. May allocate using %GFP_KERNEL.
1650 * Return: vm_fault_t value.
1651 */
1652vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1653 unsigned long pfn, pgprot_t pgprot)
1654{
1655 /*
1656 * Technically, architectures with pte_special can avoid all these
1657 * restrictions (same for remap_pfn_range). However we would like
1658 * consistency in testing and feature parity among all, so we should
1659 * try to keep these invariants in place for everybody.
1660 */
1661 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1662 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1663 (VM_PFNMAP|VM_MIXEDMAP));
1664 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1665 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1666
1667 if (addr < vma->vm_start || addr >= vma->vm_end)
1668 return VM_FAULT_SIGBUS;
1669
1670 if (!pfn_modify_allowed(pfn, pgprot))
1671 return VM_FAULT_SIGBUS;
1672
1673 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1674
1675 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1676 false);
1677}
1678EXPORT_SYMBOL(vmf_insert_pfn_prot);
1679
1680/**
1681 * vmf_insert_pfn - insert single pfn into user vma
1682 * @vma: user vma to map to
1683 * @addr: target user address of this page
1684 * @pfn: source kernel pfn
1685 *
1686 * Similar to vm_insert_page, this allows drivers to insert individual pages
1687 * they've allocated into a user vma. Same comments apply.
1688 *
1689 * This function should only be called from a vm_ops->fault handler, and
1690 * in that case the handler should return the result of this function.
1691 *
1692 * vma cannot be a COW mapping.
1693 *
1694 * As this is called only for pages that do not currently exist, we
1695 * do not need to flush old virtual caches or the TLB.
1696 *
1697 * Context: Process context. May allocate using %GFP_KERNEL.
1698 * Return: vm_fault_t value.
1699 */
1700vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1701 unsigned long pfn)
1702{
1703 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1704}
1705EXPORT_SYMBOL(vmf_insert_pfn);
1706
1707static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
1708{
1709 /* these checks mirror the abort conditions in vm_normal_page */
1710 if (vma->vm_flags & VM_MIXEDMAP)
1711 return true;
1712 if (pfn_t_devmap(pfn))
1713 return true;
1714 if (pfn_t_special(pfn))
1715 return true;
1716 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
1717 return true;
1718 return false;
1719}
1720
1721static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
1722 unsigned long addr, pfn_t pfn, bool mkwrite)
1723{
1724 pgprot_t pgprot = vma->vm_page_prot;
1725 int err;
1726
1727 BUG_ON(!vm_mixed_ok(vma, pfn));
1728
1729 if (addr < vma->vm_start || addr >= vma->vm_end)
1730 return VM_FAULT_SIGBUS;
1731
1732 track_pfn_insert(vma, &pgprot, pfn);
1733
1734 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
1735 return VM_FAULT_SIGBUS;
1736
1737 /*
1738 * If we don't have pte special, then we have to use the pfn_valid()
1739 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1740 * refcount the page if pfn_valid is true (hence insert_page rather
1741 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1742 * without pte special, it would there be refcounted as a normal page.
1743 */
1744 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
1745 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1746 struct page *page;
1747
1748 /*
1749 * At this point we are committed to insert_page()
1750 * regardless of whether the caller specified flags that
1751 * result in pfn_t_has_page() == false.
1752 */
1753 page = pfn_to_page(pfn_t_to_pfn(pfn));
1754 err = insert_page(vma, addr, page, pgprot);
1755 } else {
1756 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1757 }
1758
1759 if (err == -ENOMEM)
1760 return VM_FAULT_OOM;
1761 if (err < 0 && err != -EBUSY)
1762 return VM_FAULT_SIGBUS;
1763
1764 return VM_FAULT_NOPAGE;
1765}
1766
1767vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1768 pfn_t pfn)
1769{
1770 return __vm_insert_mixed(vma, addr, pfn, false);
1771}
1772EXPORT_SYMBOL(vmf_insert_mixed);
1773
1774/*
1775 * If the insertion of PTE failed because someone else already added a
1776 * different entry in the mean time, we treat that as success as we assume
1777 * the same entry was actually inserted.
1778 */
1779vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
1780 unsigned long addr, pfn_t pfn)
1781{
1782 return __vm_insert_mixed(vma, addr, pfn, true);
1783}
1784EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
1785
1786/*
1787 * maps a range of physical memory into the requested pages. the old
1788 * mappings are removed. any references to nonexistent pages results
1789 * in null mappings (currently treated as "copy-on-access")
1790 */
1791static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1792 unsigned long addr, unsigned long end,
1793 unsigned long pfn, pgprot_t prot)
1794{
1795 pte_t *pte;
1796 spinlock_t *ptl;
1797 int err = 0;
1798
1799 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1800 if (!pte)
1801 return -ENOMEM;
1802 arch_enter_lazy_mmu_mode();
1803 do {
1804 BUG_ON(!pte_none(*pte));
1805 if (!pfn_modify_allowed(pfn, prot)) {
1806 err = -EACCES;
1807 break;
1808 }
1809 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1810 pfn++;
1811 } while (pte++, addr += PAGE_SIZE, addr != end);
1812 arch_leave_lazy_mmu_mode();
1813 pte_unmap_unlock(pte - 1, ptl);
1814 return err;
1815}
1816
1817static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1818 unsigned long addr, unsigned long end,
1819 unsigned long pfn, pgprot_t prot)
1820{
1821 pmd_t *pmd;
1822 unsigned long next;
1823 int err;
1824
1825 pfn -= addr >> PAGE_SHIFT;
1826 pmd = pmd_alloc(mm, pud, addr);
1827 if (!pmd)
1828 return -ENOMEM;
1829 VM_BUG_ON(pmd_trans_huge(*pmd));
1830 do {
1831 next = pmd_addr_end(addr, end);
1832 err = remap_pte_range(mm, pmd, addr, next,
1833 pfn + (addr >> PAGE_SHIFT), prot);
1834 if (err)
1835 return err;
1836 } while (pmd++, addr = next, addr != end);
1837 return 0;
1838}
1839
1840static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
1841 unsigned long addr, unsigned long end,
1842 unsigned long pfn, pgprot_t prot)
1843{
1844 pud_t *pud;
1845 unsigned long next;
1846 int err;
1847
1848 pfn -= addr >> PAGE_SHIFT;
1849 pud = pud_alloc(mm, p4d, addr);
1850 if (!pud)
1851 return -ENOMEM;
1852 do {
1853 next = pud_addr_end(addr, end);
1854 err = remap_pmd_range(mm, pud, addr, next,
1855 pfn + (addr >> PAGE_SHIFT), prot);
1856 if (err)
1857 return err;
1858 } while (pud++, addr = next, addr != end);
1859 return 0;
1860}
1861
1862static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
1863 unsigned long addr, unsigned long end,
1864 unsigned long pfn, pgprot_t prot)
1865{
1866 p4d_t *p4d;
1867 unsigned long next;
1868 int err;
1869
1870 pfn -= addr >> PAGE_SHIFT;
1871 p4d = p4d_alloc(mm, pgd, addr);
1872 if (!p4d)
1873 return -ENOMEM;
1874 do {
1875 next = p4d_addr_end(addr, end);
1876 err = remap_pud_range(mm, p4d, addr, next,
1877 pfn + (addr >> PAGE_SHIFT), prot);
1878 if (err)
1879 return err;
1880 } while (p4d++, addr = next, addr != end);
1881 return 0;
1882}
1883
1884/**
1885 * remap_pfn_range - remap kernel memory to userspace
1886 * @vma: user vma to map to
1887 * @addr: target user address to start at
1888 * @pfn: physical address of kernel memory
1889 * @size: size of map area
1890 * @prot: page protection flags for this mapping
1891 *
1892 * Note: this is only safe if the mm semaphore is held when called.
1893 *
1894 * Return: %0 on success, negative error code otherwise.
1895 */
1896int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1897 unsigned long pfn, unsigned long size, pgprot_t prot)
1898{
1899 pgd_t *pgd;
1900 unsigned long next;
1901 unsigned long end = addr + PAGE_ALIGN(size);
1902 struct mm_struct *mm = vma->vm_mm;
1903 unsigned long remap_pfn = pfn;
1904 int err;
1905
1906 /*
1907 * Physically remapped pages are special. Tell the
1908 * rest of the world about it:
1909 * VM_IO tells people not to look at these pages
1910 * (accesses can have side effects).
1911 * VM_PFNMAP tells the core MM that the base pages are just
1912 * raw PFN mappings, and do not have a "struct page" associated
1913 * with them.
1914 * VM_DONTEXPAND
1915 * Disable vma merging and expanding with mremap().
1916 * VM_DONTDUMP
1917 * Omit vma from core dump, even when VM_IO turned off.
1918 *
1919 * There's a horrible special case to handle copy-on-write
1920 * behaviour that some programs depend on. We mark the "original"
1921 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1922 * See vm_normal_page() for details.
1923 */
1924 if (is_cow_mapping(vma->vm_flags)) {
1925 if (addr != vma->vm_start || end != vma->vm_end)
1926 return -EINVAL;
1927 vma->vm_pgoff = pfn;
1928 }
1929
1930 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1931 if (err)
1932 return -EINVAL;
1933
1934 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1935
1936 BUG_ON(addr >= end);
1937 pfn -= addr >> PAGE_SHIFT;
1938 pgd = pgd_offset(mm, addr);
1939 flush_cache_range(vma, addr, end);
1940 do {
1941 next = pgd_addr_end(addr, end);
1942 err = remap_p4d_range(mm, pgd, addr, next,
1943 pfn + (addr >> PAGE_SHIFT), prot);
1944 if (err)
1945 break;
1946 } while (pgd++, addr = next, addr != end);
1947
1948 if (err)
1949 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1950
1951 return err;
1952}
1953EXPORT_SYMBOL(remap_pfn_range);
1954
1955/**
1956 * vm_iomap_memory - remap memory to userspace
1957 * @vma: user vma to map to
1958 * @start: start of area
1959 * @len: size of area
1960 *
1961 * This is a simplified io_remap_pfn_range() for common driver use. The
1962 * driver just needs to give us the physical memory range to be mapped,
1963 * we'll figure out the rest from the vma information.
1964 *
1965 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1966 * whatever write-combining details or similar.
1967 *
1968 * Return: %0 on success, negative error code otherwise.
1969 */
1970int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1971{
1972 unsigned long vm_len, pfn, pages;
1973
1974 /* Check that the physical memory area passed in looks valid */
1975 if (start + len < start)
1976 return -EINVAL;
1977 /*
1978 * You *really* shouldn't map things that aren't page-aligned,
1979 * but we've historically allowed it because IO memory might
1980 * just have smaller alignment.
1981 */
1982 len += start & ~PAGE_MASK;
1983 pfn = start >> PAGE_SHIFT;
1984 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1985 if (pfn + pages < pfn)
1986 return -EINVAL;
1987
1988 /* We start the mapping 'vm_pgoff' pages into the area */
1989 if (vma->vm_pgoff > pages)
1990 return -EINVAL;
1991 pfn += vma->vm_pgoff;
1992 pages -= vma->vm_pgoff;
1993
1994 /* Can we fit all of the mapping? */
1995 vm_len = vma->vm_end - vma->vm_start;
1996 if (vm_len >> PAGE_SHIFT > pages)
1997 return -EINVAL;
1998
1999 /* Ok, let it rip */
2000 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2001}
2002EXPORT_SYMBOL(vm_iomap_memory);
2003
2004static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2005 unsigned long addr, unsigned long end,
2006 pte_fn_t fn, void *data)
2007{
2008 pte_t *pte;
2009 int err;
2010 spinlock_t *uninitialized_var(ptl);
2011
2012 pte = (mm == &init_mm) ?
2013 pte_alloc_kernel(pmd, addr) :
2014 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2015 if (!pte)
2016 return -ENOMEM;
2017
2018 BUG_ON(pmd_huge(*pmd));
2019
2020 arch_enter_lazy_mmu_mode();
2021
2022 do {
2023 err = fn(pte++, addr, data);
2024 if (err)
2025 break;
2026 } while (addr += PAGE_SIZE, addr != end);
2027
2028 arch_leave_lazy_mmu_mode();
2029
2030 if (mm != &init_mm)
2031 pte_unmap_unlock(pte-1, ptl);
2032 return err;
2033}
2034
2035static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2036 unsigned long addr, unsigned long end,
2037 pte_fn_t fn, void *data)
2038{
2039 pmd_t *pmd;
2040 unsigned long next;
2041 int err;
2042
2043 BUG_ON(pud_huge(*pud));
2044
2045 pmd = pmd_alloc(mm, pud, addr);
2046 if (!pmd)
2047 return -ENOMEM;
2048 do {
2049 next = pmd_addr_end(addr, end);
2050 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2051 if (err)
2052 break;
2053 } while (pmd++, addr = next, addr != end);
2054 return err;
2055}
2056
2057static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2058 unsigned long addr, unsigned long end,
2059 pte_fn_t fn, void *data)
2060{
2061 pud_t *pud;
2062 unsigned long next;
2063 int err;
2064
2065 pud = pud_alloc(mm, p4d, addr);
2066 if (!pud)
2067 return -ENOMEM;
2068 do {
2069 next = pud_addr_end(addr, end);
2070 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2071 if (err)
2072 break;
2073 } while (pud++, addr = next, addr != end);
2074 return err;
2075}
2076
2077static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2078 unsigned long addr, unsigned long end,
2079 pte_fn_t fn, void *data)
2080{
2081 p4d_t *p4d;
2082 unsigned long next;
2083 int err;
2084
2085 p4d = p4d_alloc(mm, pgd, addr);
2086 if (!p4d)
2087 return -ENOMEM;
2088 do {
2089 next = p4d_addr_end(addr, end);
2090 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2091 if (err)
2092 break;
2093 } while (p4d++, addr = next, addr != end);
2094 return err;
2095}
2096
2097/*
2098 * Scan a region of virtual memory, filling in page tables as necessary
2099 * and calling a provided function on each leaf page table.
2100 */
2101int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2102 unsigned long size, pte_fn_t fn, void *data)
2103{
2104 pgd_t *pgd;
2105 unsigned long next;
2106 unsigned long end = addr + size;
2107 int err;
2108
2109 if (WARN_ON(addr >= end))
2110 return -EINVAL;
2111
2112 pgd = pgd_offset(mm, addr);
2113 do {
2114 next = pgd_addr_end(addr, end);
2115 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2116 if (err)
2117 break;
2118 } while (pgd++, addr = next, addr != end);
2119
2120 return err;
2121}
2122EXPORT_SYMBOL_GPL(apply_to_page_range);
2123
2124/*
2125 * handle_pte_fault chooses page fault handler according to an entry which was
2126 * read non-atomically. Before making any commitment, on those architectures
2127 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2128 * parts, do_swap_page must check under lock before unmapping the pte and
2129 * proceeding (but do_wp_page is only called after already making such a check;
2130 * and do_anonymous_page can safely check later on).
2131 */
2132static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2133 pte_t *page_table, pte_t orig_pte)
2134{
2135 int same = 1;
2136#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2137 if (sizeof(pte_t) > sizeof(unsigned long)) {
2138 spinlock_t *ptl = pte_lockptr(mm, pmd);
2139 spin_lock(ptl);
2140 same = pte_same(*page_table, orig_pte);
2141 spin_unlock(ptl);
2142 }
2143#endif
2144 pte_unmap(page_table);
2145 return same;
2146}
2147
2148static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2149{
2150 debug_dma_assert_idle(src);
2151
2152 /*
2153 * If the source page was a PFN mapping, we don't have
2154 * a "struct page" for it. We do a best-effort copy by
2155 * just copying from the original user address. If that
2156 * fails, we just zero-fill it. Live with it.
2157 */
2158 if (unlikely(!src)) {
2159 void *kaddr = kmap_atomic(dst);
2160 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2161
2162 /*
2163 * This really shouldn't fail, because the page is there
2164 * in the page tables. But it might just be unreadable,
2165 * in which case we just give up and fill the result with
2166 * zeroes.
2167 */
2168 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2169 clear_page(kaddr);
2170 kunmap_atomic(kaddr);
2171 flush_dcache_page(dst);
2172 } else
2173 copy_user_highpage(dst, src, va, vma);
2174}
2175
2176static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2177{
2178 struct file *vm_file = vma->vm_file;
2179
2180 if (vm_file)
2181 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2182
2183 /*
2184 * Special mappings (e.g. VDSO) do not have any file so fake
2185 * a default GFP_KERNEL for them.
2186 */
2187 return GFP_KERNEL;
2188}
2189
2190/*
2191 * Notify the address space that the page is about to become writable so that
2192 * it can prohibit this or wait for the page to get into an appropriate state.
2193 *
2194 * We do this without the lock held, so that it can sleep if it needs to.
2195 */
2196static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
2197{
2198 vm_fault_t ret;
2199 struct page *page = vmf->page;
2200 unsigned int old_flags = vmf->flags;
2201
2202 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2203
2204 if (vmf->vma->vm_file &&
2205 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
2206 return VM_FAULT_SIGBUS;
2207
2208 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2209 /* Restore original flags so that caller is not surprised */
2210 vmf->flags = old_flags;
2211 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2212 return ret;
2213 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2214 lock_page(page);
2215 if (!page->mapping) {
2216 unlock_page(page);
2217 return 0; /* retry */
2218 }
2219 ret |= VM_FAULT_LOCKED;
2220 } else
2221 VM_BUG_ON_PAGE(!PageLocked(page), page);
2222 return ret;
2223}
2224
2225/*
2226 * Handle dirtying of a page in shared file mapping on a write fault.
2227 *
2228 * The function expects the page to be locked and unlocks it.
2229 */
2230static void fault_dirty_shared_page(struct vm_area_struct *vma,
2231 struct page *page)
2232{
2233 struct address_space *mapping;
2234 bool dirtied;
2235 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2236
2237 dirtied = set_page_dirty(page);
2238 VM_BUG_ON_PAGE(PageAnon(page), page);
2239 /*
2240 * Take a local copy of the address_space - page.mapping may be zeroed
2241 * by truncate after unlock_page(). The address_space itself remains
2242 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2243 * release semantics to prevent the compiler from undoing this copying.
2244 */
2245 mapping = page_rmapping(page);
2246 unlock_page(page);
2247
2248 if ((dirtied || page_mkwrite) && mapping) {
2249 /*
2250 * Some device drivers do not set page.mapping
2251 * but still dirty their pages
2252 */
2253 balance_dirty_pages_ratelimited(mapping);
2254 }
2255
2256 if (!page_mkwrite)
2257 file_update_time(vma->vm_file);
2258}
2259
2260/*
2261 * Handle write page faults for pages that can be reused in the current vma
2262 *
2263 * This can happen either due to the mapping being with the VM_SHARED flag,
2264 * or due to us being the last reference standing to the page. In either
2265 * case, all we need to do here is to mark the page as writable and update
2266 * any related book-keeping.
2267 */
2268static inline void wp_page_reuse(struct vm_fault *vmf)
2269 __releases(vmf->ptl)
2270{
2271 struct vm_area_struct *vma = vmf->vma;
2272 struct page *page = vmf->page;
2273 pte_t entry;
2274 /*
2275 * Clear the pages cpupid information as the existing
2276 * information potentially belongs to a now completely
2277 * unrelated process.
2278 */
2279 if (page)
2280 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2281
2282 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2283 entry = pte_mkyoung(vmf->orig_pte);
2284 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2285 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2286 update_mmu_cache(vma, vmf->address, vmf->pte);
2287 pte_unmap_unlock(vmf->pte, vmf->ptl);
2288}
2289
2290/*
2291 * Handle the case of a page which we actually need to copy to a new page.
2292 *
2293 * Called with mmap_sem locked and the old page referenced, but
2294 * without the ptl held.
2295 *
2296 * High level logic flow:
2297 *
2298 * - Allocate a page, copy the content of the old page to the new one.
2299 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2300 * - Take the PTL. If the pte changed, bail out and release the allocated page
2301 * - If the pte is still the way we remember it, update the page table and all
2302 * relevant references. This includes dropping the reference the page-table
2303 * held to the old page, as well as updating the rmap.
2304 * - In any case, unlock the PTL and drop the reference we took to the old page.
2305 */
2306static vm_fault_t wp_page_copy(struct vm_fault *vmf)
2307{
2308 struct vm_area_struct *vma = vmf->vma;
2309 struct mm_struct *mm = vma->vm_mm;
2310 struct page *old_page = vmf->page;
2311 struct page *new_page = NULL;
2312 pte_t entry;
2313 int page_copied = 0;
2314 struct mem_cgroup *memcg;
2315 struct mmu_notifier_range range;
2316
2317 if (unlikely(anon_vma_prepare(vma)))
2318 goto oom;
2319
2320 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2321 new_page = alloc_zeroed_user_highpage_movable(vma,
2322 vmf->address);
2323 if (!new_page)
2324 goto oom;
2325 } else {
2326 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2327 vmf->address);
2328 if (!new_page)
2329 goto oom;
2330 cow_user_page(new_page, old_page, vmf->address, vma);
2331 }
2332
2333 if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))
2334 goto oom_free_new;
2335
2336 __SetPageUptodate(new_page);
2337
2338 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
2339 vmf->address & PAGE_MASK,
2340 (vmf->address & PAGE_MASK) + PAGE_SIZE);
2341 mmu_notifier_invalidate_range_start(&range);
2342
2343 /*
2344 * Re-check the pte - we dropped the lock
2345 */
2346 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2347 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2348 if (old_page) {
2349 if (!PageAnon(old_page)) {
2350 dec_mm_counter_fast(mm,
2351 mm_counter_file(old_page));
2352 inc_mm_counter_fast(mm, MM_ANONPAGES);
2353 }
2354 } else {
2355 inc_mm_counter_fast(mm, MM_ANONPAGES);
2356 }
2357 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2358 entry = mk_pte(new_page, vma->vm_page_prot);
2359 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2360 /*
2361 * Clear the pte entry and flush it first, before updating the
2362 * pte with the new entry. This will avoid a race condition
2363 * seen in the presence of one thread doing SMC and another
2364 * thread doing COW.
2365 */
2366 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2367 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2368 mem_cgroup_commit_charge(new_page, memcg, false, false);
2369 lru_cache_add_active_or_unevictable(new_page, vma);
2370 /*
2371 * We call the notify macro here because, when using secondary
2372 * mmu page tables (such as kvm shadow page tables), we want the
2373 * new page to be mapped directly into the secondary page table.
2374 */
2375 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2376 update_mmu_cache(vma, vmf->address, vmf->pte);
2377 if (old_page) {
2378 /*
2379 * Only after switching the pte to the new page may
2380 * we remove the mapcount here. Otherwise another
2381 * process may come and find the rmap count decremented
2382 * before the pte is switched to the new page, and
2383 * "reuse" the old page writing into it while our pte
2384 * here still points into it and can be read by other
2385 * threads.
2386 *
2387 * The critical issue is to order this
2388 * page_remove_rmap with the ptp_clear_flush above.
2389 * Those stores are ordered by (if nothing else,)
2390 * the barrier present in the atomic_add_negative
2391 * in page_remove_rmap.
2392 *
2393 * Then the TLB flush in ptep_clear_flush ensures that
2394 * no process can access the old page before the
2395 * decremented mapcount is visible. And the old page
2396 * cannot be reused until after the decremented
2397 * mapcount is visible. So transitively, TLBs to
2398 * old page will be flushed before it can be reused.
2399 */
2400 page_remove_rmap(old_page, false);
2401 }
2402
2403 /* Free the old page.. */
2404 new_page = old_page;
2405 page_copied = 1;
2406 } else {
2407 mem_cgroup_cancel_charge(new_page, memcg, false);
2408 }
2409
2410 if (new_page)
2411 put_page(new_page);
2412
2413 pte_unmap_unlock(vmf->pte, vmf->ptl);
2414 /*
2415 * No need to double call mmu_notifier->invalidate_range() callback as
2416 * the above ptep_clear_flush_notify() did already call it.
2417 */
2418 mmu_notifier_invalidate_range_only_end(&range);
2419 if (old_page) {
2420 /*
2421 * Don't let another task, with possibly unlocked vma,
2422 * keep the mlocked page.
2423 */
2424 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2425 lock_page(old_page); /* LRU manipulation */
2426 if (PageMlocked(old_page))
2427 munlock_vma_page(old_page);
2428 unlock_page(old_page);
2429 }
2430 put_page(old_page);
2431 }
2432 return page_copied ? VM_FAULT_WRITE : 0;
2433oom_free_new:
2434 put_page(new_page);
2435oom:
2436 if (old_page)
2437 put_page(old_page);
2438 return VM_FAULT_OOM;
2439}
2440
2441/**
2442 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2443 * writeable once the page is prepared
2444 *
2445 * @vmf: structure describing the fault
2446 *
2447 * This function handles all that is needed to finish a write page fault in a
2448 * shared mapping due to PTE being read-only once the mapped page is prepared.
2449 * It handles locking of PTE and modifying it.
2450 *
2451 * The function expects the page to be locked or other protection against
2452 * concurrent faults / writeback (such as DAX radix tree locks).
2453 *
2454 * Return: %VM_FAULT_WRITE on success, %0 when PTE got changed before
2455 * we acquired PTE lock.
2456 */
2457vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
2458{
2459 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2460 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2461 &vmf->ptl);
2462 /*
2463 * We might have raced with another page fault while we released the
2464 * pte_offset_map_lock.
2465 */
2466 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2467 pte_unmap_unlock(vmf->pte, vmf->ptl);
2468 return VM_FAULT_NOPAGE;
2469 }
2470 wp_page_reuse(vmf);
2471 return 0;
2472}
2473
2474/*
2475 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2476 * mapping
2477 */
2478static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
2479{
2480 struct vm_area_struct *vma = vmf->vma;
2481
2482 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2483 vm_fault_t ret;
2484
2485 pte_unmap_unlock(vmf->pte, vmf->ptl);
2486 vmf->flags |= FAULT_FLAG_MKWRITE;
2487 ret = vma->vm_ops->pfn_mkwrite(vmf);
2488 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2489 return ret;
2490 return finish_mkwrite_fault(vmf);
2491 }
2492 wp_page_reuse(vmf);
2493 return VM_FAULT_WRITE;
2494}
2495
2496static vm_fault_t wp_page_shared(struct vm_fault *vmf)
2497 __releases(vmf->ptl)
2498{
2499 struct vm_area_struct *vma = vmf->vma;
2500
2501 get_page(vmf->page);
2502
2503 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2504 vm_fault_t tmp;
2505
2506 pte_unmap_unlock(vmf->pte, vmf->ptl);
2507 tmp = do_page_mkwrite(vmf);
2508 if (unlikely(!tmp || (tmp &
2509 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2510 put_page(vmf->page);
2511 return tmp;
2512 }
2513 tmp = finish_mkwrite_fault(vmf);
2514 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2515 unlock_page(vmf->page);
2516 put_page(vmf->page);
2517 return tmp;
2518 }
2519 } else {
2520 wp_page_reuse(vmf);
2521 lock_page(vmf->page);
2522 }
2523 fault_dirty_shared_page(vma, vmf->page);
2524 put_page(vmf->page);
2525
2526 return VM_FAULT_WRITE;
2527}
2528
2529/*
2530 * This routine handles present pages, when users try to write
2531 * to a shared page. It is done by copying the page to a new address
2532 * and decrementing the shared-page counter for the old page.
2533 *
2534 * Note that this routine assumes that the protection checks have been
2535 * done by the caller (the low-level page fault routine in most cases).
2536 * Thus we can safely just mark it writable once we've done any necessary
2537 * COW.
2538 *
2539 * We also mark the page dirty at this point even though the page will
2540 * change only once the write actually happens. This avoids a few races,
2541 * and potentially makes it more efficient.
2542 *
2543 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2544 * but allow concurrent faults), with pte both mapped and locked.
2545 * We return with mmap_sem still held, but pte unmapped and unlocked.
2546 */
2547static vm_fault_t do_wp_page(struct vm_fault *vmf)
2548 __releases(vmf->ptl)
2549{
2550 struct vm_area_struct *vma = vmf->vma;
2551
2552 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2553 if (!vmf->page) {
2554 /*
2555 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2556 * VM_PFNMAP VMA.
2557 *
2558 * We should not cow pages in a shared writeable mapping.
2559 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2560 */
2561 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2562 (VM_WRITE|VM_SHARED))
2563 return wp_pfn_shared(vmf);
2564
2565 pte_unmap_unlock(vmf->pte, vmf->ptl);
2566 return wp_page_copy(vmf);
2567 }
2568
2569 /*
2570 * Take out anonymous pages first, anonymous shared vmas are
2571 * not dirty accountable.
2572 */
2573 if (PageAnon(vmf->page)) {
2574 int total_map_swapcount;
2575 if (PageKsm(vmf->page) && (PageSwapCache(vmf->page) ||
2576 page_count(vmf->page) != 1))
2577 goto copy;
2578 if (!trylock_page(vmf->page)) {
2579 get_page(vmf->page);
2580 pte_unmap_unlock(vmf->pte, vmf->ptl);
2581 lock_page(vmf->page);
2582 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2583 vmf->address, &vmf->ptl);
2584 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2585 unlock_page(vmf->page);
2586 pte_unmap_unlock(vmf->pte, vmf->ptl);
2587 put_page(vmf->page);
2588 return 0;
2589 }
2590 put_page(vmf->page);
2591 }
2592 if (PageKsm(vmf->page)) {
2593 bool reused = reuse_ksm_page(vmf->page, vmf->vma,
2594 vmf->address);
2595 unlock_page(vmf->page);
2596 if (!reused)
2597 goto copy;
2598 wp_page_reuse(vmf);
2599 return VM_FAULT_WRITE;
2600 }
2601 if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2602 if (total_map_swapcount == 1) {
2603 /*
2604 * The page is all ours. Move it to
2605 * our anon_vma so the rmap code will
2606 * not search our parent or siblings.
2607 * Protected against the rmap code by
2608 * the page lock.
2609 */
2610 page_move_anon_rmap(vmf->page, vma);
2611 }
2612 unlock_page(vmf->page);
2613 wp_page_reuse(vmf);
2614 return VM_FAULT_WRITE;
2615 }
2616 unlock_page(vmf->page);
2617 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2618 (VM_WRITE|VM_SHARED))) {
2619 return wp_page_shared(vmf);
2620 }
2621copy:
2622 /*
2623 * Ok, we need to copy. Oh, well..
2624 */
2625 get_page(vmf->page);
2626
2627 pte_unmap_unlock(vmf->pte, vmf->ptl);
2628 return wp_page_copy(vmf);
2629}
2630
2631static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2632 unsigned long start_addr, unsigned long end_addr,
2633 struct zap_details *details)
2634{
2635 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2636}
2637
2638static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2639 struct zap_details *details)
2640{
2641 struct vm_area_struct *vma;
2642 pgoff_t vba, vea, zba, zea;
2643
2644 vma_interval_tree_foreach(vma, root,
2645 details->first_index, details->last_index) {
2646
2647 vba = vma->vm_pgoff;
2648 vea = vba + vma_pages(vma) - 1;
2649 zba = details->first_index;
2650 if (zba < vba)
2651 zba = vba;
2652 zea = details->last_index;
2653 if (zea > vea)
2654 zea = vea;
2655
2656 unmap_mapping_range_vma(vma,
2657 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2658 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2659 details);
2660 }
2661}
2662
2663/**
2664 * unmap_mapping_pages() - Unmap pages from processes.
2665 * @mapping: The address space containing pages to be unmapped.
2666 * @start: Index of first page to be unmapped.
2667 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
2668 * @even_cows: Whether to unmap even private COWed pages.
2669 *
2670 * Unmap the pages in this address space from any userspace process which
2671 * has them mmaped. Generally, you want to remove COWed pages as well when
2672 * a file is being truncated, but not when invalidating pages from the page
2673 * cache.
2674 */
2675void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
2676 pgoff_t nr, bool even_cows)
2677{
2678 struct zap_details details = { };
2679
2680 details.check_mapping = even_cows ? NULL : mapping;
2681 details.first_index = start;
2682 details.last_index = start + nr - 1;
2683 if (details.last_index < details.first_index)
2684 details.last_index = ULONG_MAX;
2685
2686 i_mmap_lock_write(mapping);
2687 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2688 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2689 i_mmap_unlock_write(mapping);
2690}
2691
2692/**
2693 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2694 * address_space corresponding to the specified byte range in the underlying
2695 * file.
2696 *
2697 * @mapping: the address space containing mmaps to be unmapped.
2698 * @holebegin: byte in first page to unmap, relative to the start of
2699 * the underlying file. This will be rounded down to a PAGE_SIZE
2700 * boundary. Note that this is different from truncate_pagecache(), which
2701 * must keep the partial page. In contrast, we must get rid of
2702 * partial pages.
2703 * @holelen: size of prospective hole in bytes. This will be rounded
2704 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2705 * end of the file.
2706 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2707 * but 0 when invalidating pagecache, don't throw away private data.
2708 */
2709void unmap_mapping_range(struct address_space *mapping,
2710 loff_t const holebegin, loff_t const holelen, int even_cows)
2711{
2712 pgoff_t hba = holebegin >> PAGE_SHIFT;
2713 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2714
2715 /* Check for overflow. */
2716 if (sizeof(holelen) > sizeof(hlen)) {
2717 long long holeend =
2718 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2719 if (holeend & ~(long long)ULONG_MAX)
2720 hlen = ULONG_MAX - hba + 1;
2721 }
2722
2723 unmap_mapping_pages(mapping, hba, hlen, even_cows);
2724}
2725EXPORT_SYMBOL(unmap_mapping_range);
2726
2727/*
2728 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2729 * but allow concurrent faults), and pte mapped but not yet locked.
2730 * We return with pte unmapped and unlocked.
2731 *
2732 * We return with the mmap_sem locked or unlocked in the same cases
2733 * as does filemap_fault().
2734 */
2735vm_fault_t do_swap_page(struct vm_fault *vmf)
2736{
2737 struct vm_area_struct *vma = vmf->vma;
2738 struct page *page = NULL, *swapcache;
2739 struct mem_cgroup *memcg;
2740 swp_entry_t entry;
2741 pte_t pte;
2742 int locked;
2743 int exclusive = 0;
2744 vm_fault_t ret = 0;
2745
2746 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2747 goto out;
2748
2749 entry = pte_to_swp_entry(vmf->orig_pte);
2750 if (unlikely(non_swap_entry(entry))) {
2751 if (is_migration_entry(entry)) {
2752 migration_entry_wait(vma->vm_mm, vmf->pmd,
2753 vmf->address);
2754 } else if (is_device_private_entry(entry)) {
2755 vmf->page = device_private_entry_to_page(entry);
2756 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
2757 } else if (is_hwpoison_entry(entry)) {
2758 ret = VM_FAULT_HWPOISON;
2759 } else {
2760 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2761 ret = VM_FAULT_SIGBUS;
2762 }
2763 goto out;
2764 }
2765
2766
2767 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2768 page = lookup_swap_cache(entry, vma, vmf->address);
2769 swapcache = page;
2770
2771 if (!page) {
2772 struct swap_info_struct *si = swp_swap_info(entry);
2773
2774 if (si->flags & SWP_SYNCHRONOUS_IO &&
2775 __swap_count(entry) == 1) {
2776 /* skip swapcache */
2777 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2778 vmf->address);
2779 if (page) {
2780 __SetPageLocked(page);
2781 __SetPageSwapBacked(page);
2782 set_page_private(page, entry.val);
2783 lru_cache_add_anon(page);
2784 swap_readpage(page, true);
2785 }
2786 } else {
2787 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
2788 vmf);
2789 swapcache = page;
2790 }
2791
2792 if (!page) {
2793 /*
2794 * Back out if somebody else faulted in this pte
2795 * while we released the pte lock.
2796 */
2797 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2798 vmf->address, &vmf->ptl);
2799 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2800 ret = VM_FAULT_OOM;
2801 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2802 goto unlock;
2803 }
2804
2805 /* Had to read the page from swap area: Major fault */
2806 ret = VM_FAULT_MAJOR;
2807 count_vm_event(PGMAJFAULT);
2808 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2809 } else if (PageHWPoison(page)) {
2810 /*
2811 * hwpoisoned dirty swapcache pages are kept for killing
2812 * owner processes (which may be unknown at hwpoison time)
2813 */
2814 ret = VM_FAULT_HWPOISON;
2815 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2816 goto out_release;
2817 }
2818
2819 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2820
2821 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2822 if (!locked) {
2823 ret |= VM_FAULT_RETRY;
2824 goto out_release;
2825 }
2826
2827 /*
2828 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2829 * release the swapcache from under us. The page pin, and pte_same
2830 * test below, are not enough to exclude that. Even if it is still
2831 * swapcache, we need to check that the page's swap has not changed.
2832 */
2833 if (unlikely((!PageSwapCache(page) ||
2834 page_private(page) != entry.val)) && swapcache)
2835 goto out_page;
2836
2837 page = ksm_might_need_to_copy(page, vma, vmf->address);
2838 if (unlikely(!page)) {
2839 ret = VM_FAULT_OOM;
2840 page = swapcache;
2841 goto out_page;
2842 }
2843
2844 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL,
2845 &memcg, false)) {
2846 ret = VM_FAULT_OOM;
2847 goto out_page;
2848 }
2849
2850 /*
2851 * Back out if somebody else already faulted in this pte.
2852 */
2853 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2854 &vmf->ptl);
2855 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2856 goto out_nomap;
2857
2858 if (unlikely(!PageUptodate(page))) {
2859 ret = VM_FAULT_SIGBUS;
2860 goto out_nomap;
2861 }
2862
2863 /*
2864 * The page isn't present yet, go ahead with the fault.
2865 *
2866 * Be careful about the sequence of operations here.
2867 * To get its accounting right, reuse_swap_page() must be called
2868 * while the page is counted on swap but not yet in mapcount i.e.
2869 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2870 * must be called after the swap_free(), or it will never succeed.
2871 */
2872
2873 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2874 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2875 pte = mk_pte(page, vma->vm_page_prot);
2876 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2877 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2878 vmf->flags &= ~FAULT_FLAG_WRITE;
2879 ret |= VM_FAULT_WRITE;
2880 exclusive = RMAP_EXCLUSIVE;
2881 }
2882 flush_icache_page(vma, page);
2883 if (pte_swp_soft_dirty(vmf->orig_pte))
2884 pte = pte_mksoft_dirty(pte);
2885 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
2886 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
2887 vmf->orig_pte = pte;
2888
2889 /* ksm created a completely new copy */
2890 if (unlikely(page != swapcache && swapcache)) {
2891 page_add_new_anon_rmap(page, vma, vmf->address, false);
2892 mem_cgroup_commit_charge(page, memcg, false, false);
2893 lru_cache_add_active_or_unevictable(page, vma);
2894 } else {
2895 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2896 mem_cgroup_commit_charge(page, memcg, true, false);
2897 activate_page(page);
2898 }
2899
2900 swap_free(entry);
2901 if (mem_cgroup_swap_full(page) ||
2902 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2903 try_to_free_swap(page);
2904 unlock_page(page);
2905 if (page != swapcache && swapcache) {
2906 /*
2907 * Hold the lock to avoid the swap entry to be reused
2908 * until we take the PT lock for the pte_same() check
2909 * (to avoid false positives from pte_same). For
2910 * further safety release the lock after the swap_free
2911 * so that the swap count won't change under a
2912 * parallel locked swapcache.
2913 */
2914 unlock_page(swapcache);
2915 put_page(swapcache);
2916 }
2917
2918 if (vmf->flags & FAULT_FLAG_WRITE) {
2919 ret |= do_wp_page(vmf);
2920 if (ret & VM_FAULT_ERROR)
2921 ret &= VM_FAULT_ERROR;
2922 goto out;
2923 }
2924
2925 /* No need to invalidate - it was non-present before */
2926 update_mmu_cache(vma, vmf->address, vmf->pte);
2927unlock:
2928 pte_unmap_unlock(vmf->pte, vmf->ptl);
2929out:
2930 return ret;
2931out_nomap:
2932 mem_cgroup_cancel_charge(page, memcg, false);
2933 pte_unmap_unlock(vmf->pte, vmf->ptl);
2934out_page:
2935 unlock_page(page);
2936out_release:
2937 put_page(page);
2938 if (page != swapcache && swapcache) {
2939 unlock_page(swapcache);
2940 put_page(swapcache);
2941 }
2942 return ret;
2943}
2944
2945/*
2946 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2947 * but allow concurrent faults), and pte mapped but not yet locked.
2948 * We return with mmap_sem still held, but pte unmapped and unlocked.
2949 */
2950static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
2951{
2952 struct vm_area_struct *vma = vmf->vma;
2953 struct mem_cgroup *memcg;
2954 struct page *page;
2955 vm_fault_t ret = 0;
2956 pte_t entry;
2957
2958 /* File mapping without ->vm_ops ? */
2959 if (vma->vm_flags & VM_SHARED)
2960 return VM_FAULT_SIGBUS;
2961
2962 /*
2963 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2964 * pte_offset_map() on pmds where a huge pmd might be created
2965 * from a different thread.
2966 *
2967 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2968 * parallel threads are excluded by other means.
2969 *
2970 * Here we only have down_read(mmap_sem).
2971 */
2972 if (pte_alloc(vma->vm_mm, vmf->pmd))
2973 return VM_FAULT_OOM;
2974
2975 /* See the comment in pte_alloc_one_map() */
2976 if (unlikely(pmd_trans_unstable(vmf->pmd)))
2977 return 0;
2978
2979 /* Use the zero-page for reads */
2980 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
2981 !mm_forbids_zeropage(vma->vm_mm)) {
2982 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
2983 vma->vm_page_prot));
2984 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2985 vmf->address, &vmf->ptl);
2986 if (!pte_none(*vmf->pte))
2987 goto unlock;
2988 ret = check_stable_address_space(vma->vm_mm);
2989 if (ret)
2990 goto unlock;
2991 /* Deliver the page fault to userland, check inside PT lock */
2992 if (userfaultfd_missing(vma)) {
2993 pte_unmap_unlock(vmf->pte, vmf->ptl);
2994 return handle_userfault(vmf, VM_UFFD_MISSING);
2995 }
2996 goto setpte;
2997 }
2998
2999 /* Allocate our own private page. */
3000 if (unlikely(anon_vma_prepare(vma)))
3001 goto oom;
3002 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3003 if (!page)
3004 goto oom;
3005
3006 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL, &memcg,
3007 false))
3008 goto oom_free_page;
3009
3010 /*
3011 * The memory barrier inside __SetPageUptodate makes sure that
3012 * preceeding stores to the page contents become visible before
3013 * the set_pte_at() write.
3014 */
3015 __SetPageUptodate(page);
3016
3017 entry = mk_pte(page, vma->vm_page_prot);
3018 if (vma->vm_flags & VM_WRITE)
3019 entry = pte_mkwrite(pte_mkdirty(entry));
3020
3021 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3022 &vmf->ptl);
3023 if (!pte_none(*vmf->pte))
3024 goto release;
3025
3026 ret = check_stable_address_space(vma->vm_mm);
3027 if (ret)
3028 goto release;
3029
3030 /* Deliver the page fault to userland, check inside PT lock */
3031 if (userfaultfd_missing(vma)) {
3032 pte_unmap_unlock(vmf->pte, vmf->ptl);
3033 mem_cgroup_cancel_charge(page, memcg, false);
3034 put_page(page);
3035 return handle_userfault(vmf, VM_UFFD_MISSING);
3036 }
3037
3038 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3039 page_add_new_anon_rmap(page, vma, vmf->address, false);
3040 mem_cgroup_commit_charge(page, memcg, false, false);
3041 lru_cache_add_active_or_unevictable(page, vma);
3042setpte:
3043 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3044
3045 /* No need to invalidate - it was non-present before */
3046 update_mmu_cache(vma, vmf->address, vmf->pte);
3047unlock:
3048 pte_unmap_unlock(vmf->pte, vmf->ptl);
3049 return ret;
3050release:
3051 mem_cgroup_cancel_charge(page, memcg, false);
3052 put_page(page);
3053 goto unlock;
3054oom_free_page:
3055 put_page(page);
3056oom:
3057 return VM_FAULT_OOM;
3058}
3059
3060/*
3061 * The mmap_sem must have been held on entry, and may have been
3062 * released depending on flags and vma->vm_ops->fault() return value.
3063 * See filemap_fault() and __lock_page_retry().
3064 */
3065static vm_fault_t __do_fault(struct vm_fault *vmf)
3066{
3067 struct vm_area_struct *vma = vmf->vma;
3068 vm_fault_t ret;
3069
3070 /*
3071 * Preallocate pte before we take page_lock because this might lead to
3072 * deadlocks for memcg reclaim which waits for pages under writeback:
3073 * lock_page(A)
3074 * SetPageWriteback(A)
3075 * unlock_page(A)
3076 * lock_page(B)
3077 * lock_page(B)
3078 * pte_alloc_pne
3079 * shrink_page_list
3080 * wait_on_page_writeback(A)
3081 * SetPageWriteback(B)
3082 * unlock_page(B)
3083 * # flush A, B to clear the writeback
3084 */
3085 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
3086 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
3087 if (!vmf->prealloc_pte)
3088 return VM_FAULT_OOM;
3089 smp_wmb(); /* See comment in __pte_alloc() */
3090 }
3091
3092 ret = vma->vm_ops->fault(vmf);
3093 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3094 VM_FAULT_DONE_COW)))
3095 return ret;
3096
3097 if (unlikely(PageHWPoison(vmf->page))) {
3098 if (ret & VM_FAULT_LOCKED)
3099 unlock_page(vmf->page);
3100 put_page(vmf->page);
3101 vmf->page = NULL;
3102 return VM_FAULT_HWPOISON;
3103 }
3104
3105 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3106 lock_page(vmf->page);
3107 else
3108 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3109
3110 return ret;
3111}
3112
3113/*
3114 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3115 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3116 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3117 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3118 */
3119static int pmd_devmap_trans_unstable(pmd_t *pmd)
3120{
3121 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3122}
3123
3124static vm_fault_t pte_alloc_one_map(struct vm_fault *vmf)
3125{
3126 struct vm_area_struct *vma = vmf->vma;
3127
3128 if (!pmd_none(*vmf->pmd))
3129 goto map_pte;
3130 if (vmf->prealloc_pte) {
3131 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3132 if (unlikely(!pmd_none(*vmf->pmd))) {
3133 spin_unlock(vmf->ptl);
3134 goto map_pte;
3135 }
3136
3137 mm_inc_nr_ptes(vma->vm_mm);
3138 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3139 spin_unlock(vmf->ptl);
3140 vmf->prealloc_pte = NULL;
3141 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) {
3142 return VM_FAULT_OOM;
3143 }
3144map_pte:
3145 /*
3146 * If a huge pmd materialized under us just retry later. Use
3147 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3148 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3149 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3150 * running immediately after a huge pmd fault in a different thread of
3151 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3152 * All we have to ensure is that it is a regular pmd that we can walk
3153 * with pte_offset_map() and we can do that through an atomic read in
3154 * C, which is what pmd_trans_unstable() provides.
3155 */
3156 if (pmd_devmap_trans_unstable(vmf->pmd))
3157 return VM_FAULT_NOPAGE;
3158
3159 /*
3160 * At this point we know that our vmf->pmd points to a page of ptes
3161 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3162 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3163 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3164 * be valid and we will re-check to make sure the vmf->pte isn't
3165 * pte_none() under vmf->ptl protection when we return to
3166 * alloc_set_pte().
3167 */
3168 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3169 &vmf->ptl);
3170 return 0;
3171}
3172
3173#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3174static void deposit_prealloc_pte(struct vm_fault *vmf)
3175{
3176 struct vm_area_struct *vma = vmf->vma;
3177
3178 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3179 /*
3180 * We are going to consume the prealloc table,
3181 * count that as nr_ptes.
3182 */
3183 mm_inc_nr_ptes(vma->vm_mm);
3184 vmf->prealloc_pte = NULL;
3185}
3186
3187static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3188{
3189 struct vm_area_struct *vma = vmf->vma;
3190 bool write = vmf->flags & FAULT_FLAG_WRITE;
3191 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3192 pmd_t entry;
3193 int i;
3194 vm_fault_t ret;
3195
3196 if (!transhuge_vma_suitable(vma, haddr))
3197 return VM_FAULT_FALLBACK;
3198
3199 ret = VM_FAULT_FALLBACK;
3200 page = compound_head(page);
3201
3202 /*
3203 * Archs like ppc64 need additonal space to store information
3204 * related to pte entry. Use the preallocated table for that.
3205 */
3206 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3207 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
3208 if (!vmf->prealloc_pte)
3209 return VM_FAULT_OOM;
3210 smp_wmb(); /* See comment in __pte_alloc() */
3211 }
3212
3213 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3214 if (unlikely(!pmd_none(*vmf->pmd)))
3215 goto out;
3216
3217 for (i = 0; i < HPAGE_PMD_NR; i++)
3218 flush_icache_page(vma, page + i);
3219
3220 entry = mk_huge_pmd(page, vma->vm_page_prot);
3221 if (write)
3222 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3223
3224 add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
3225 page_add_file_rmap(page, true);
3226 /*
3227 * deposit and withdraw with pmd lock held
3228 */
3229 if (arch_needs_pgtable_deposit())
3230 deposit_prealloc_pte(vmf);
3231
3232 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3233
3234 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3235
3236 /* fault is handled */
3237 ret = 0;
3238 count_vm_event(THP_FILE_MAPPED);
3239out:
3240 spin_unlock(vmf->ptl);
3241 return ret;
3242}
3243#else
3244static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
3245{
3246 BUILD_BUG();
3247 return 0;
3248}
3249#endif
3250
3251/**
3252 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3253 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3254 *
3255 * @vmf: fault environment
3256 * @memcg: memcg to charge page (only for private mappings)
3257 * @page: page to map
3258 *
3259 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3260 * return.
3261 *
3262 * Target users are page handler itself and implementations of
3263 * vm_ops->map_pages.
3264 *
3265 * Return: %0 on success, %VM_FAULT_ code in case of error.
3266 */
3267vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3268 struct page *page)
3269{
3270 struct vm_area_struct *vma = vmf->vma;
3271 bool write = vmf->flags & FAULT_FLAG_WRITE;
3272 pte_t entry;
3273 vm_fault_t ret;
3274
3275 if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3276 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3277 /* THP on COW? */
3278 VM_BUG_ON_PAGE(memcg, page);
3279
3280 ret = do_set_pmd(vmf, page);
3281 if (ret != VM_FAULT_FALLBACK)
3282 return ret;
3283 }
3284
3285 if (!vmf->pte) {
3286 ret = pte_alloc_one_map(vmf);
3287 if (ret)
3288 return ret;
3289 }
3290
3291 /* Re-check under ptl */
3292 if (unlikely(!pte_none(*vmf->pte)))
3293 return VM_FAULT_NOPAGE;
3294
3295 flush_icache_page(vma, page);
3296 entry = mk_pte(page, vma->vm_page_prot);
3297 if (write)
3298 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3299 /* copy-on-write page */
3300 if (write && !(vma->vm_flags & VM_SHARED)) {
3301 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3302 page_add_new_anon_rmap(page, vma, vmf->address, false);
3303 mem_cgroup_commit_charge(page, memcg, false, false);
3304 lru_cache_add_active_or_unevictable(page, vma);
3305 } else {
3306 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3307 page_add_file_rmap(page, false);
3308 }
3309 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3310
3311 /* no need to invalidate: a not-present page won't be cached */
3312 update_mmu_cache(vma, vmf->address, vmf->pte);
3313
3314 return 0;
3315}
3316
3317
3318/**
3319 * finish_fault - finish page fault once we have prepared the page to fault
3320 *
3321 * @vmf: structure describing the fault
3322 *
3323 * This function handles all that is needed to finish a page fault once the
3324 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3325 * given page, adds reverse page mapping, handles memcg charges and LRU
3326 * addition.
3327 *
3328 * The function expects the page to be locked and on success it consumes a
3329 * reference of a page being mapped (for the PTE which maps it).
3330 *
3331 * Return: %0 on success, %VM_FAULT_ code in case of error.
3332 */
3333vm_fault_t finish_fault(struct vm_fault *vmf)
3334{
3335 struct page *page;
3336 vm_fault_t ret = 0;
3337
3338 /* Did we COW the page? */
3339 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3340 !(vmf->vma->vm_flags & VM_SHARED))
3341 page = vmf->cow_page;
3342 else
3343 page = vmf->page;
3344
3345 /*
3346 * check even for read faults because we might have lost our CoWed
3347 * page
3348 */
3349 if (!(vmf->vma->vm_flags & VM_SHARED))
3350 ret = check_stable_address_space(vmf->vma->vm_mm);
3351 if (!ret)
3352 ret = alloc_set_pte(vmf, vmf->memcg, page);
3353 if (vmf->pte)
3354 pte_unmap_unlock(vmf->pte, vmf->ptl);
3355 return ret;
3356}
3357
3358static unsigned long fault_around_bytes __read_mostly =
3359 rounddown_pow_of_two(65536);
3360
3361#ifdef CONFIG_DEBUG_FS
3362static int fault_around_bytes_get(void *data, u64 *val)
3363{
3364 *val = fault_around_bytes;
3365 return 0;
3366}
3367
3368/*
3369 * fault_around_bytes must be rounded down to the nearest page order as it's
3370 * what do_fault_around() expects to see.
3371 */
3372static int fault_around_bytes_set(void *data, u64 val)
3373{
3374 if (val / PAGE_SIZE > PTRS_PER_PTE)
3375 return -EINVAL;
3376 if (val > PAGE_SIZE)
3377 fault_around_bytes = rounddown_pow_of_two(val);
3378 else
3379 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3380 return 0;
3381}
3382DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3383 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3384
3385static int __init fault_around_debugfs(void)
3386{
3387 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3388 &fault_around_bytes_fops);
3389 return 0;
3390}
3391late_initcall(fault_around_debugfs);
3392#endif
3393
3394/*
3395 * do_fault_around() tries to map few pages around the fault address. The hope
3396 * is that the pages will be needed soon and this will lower the number of
3397 * faults to handle.
3398 *
3399 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3400 * not ready to be mapped: not up-to-date, locked, etc.
3401 *
3402 * This function is called with the page table lock taken. In the split ptlock
3403 * case the page table lock only protects only those entries which belong to
3404 * the page table corresponding to the fault address.
3405 *
3406 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3407 * only once.
3408 *
3409 * fault_around_bytes defines how many bytes we'll try to map.
3410 * do_fault_around() expects it to be set to a power of two less than or equal
3411 * to PTRS_PER_PTE.
3412 *
3413 * The virtual address of the area that we map is naturally aligned to
3414 * fault_around_bytes rounded down to the machine page size
3415 * (and therefore to page order). This way it's easier to guarantee
3416 * that we don't cross page table boundaries.
3417 */
3418static vm_fault_t do_fault_around(struct vm_fault *vmf)
3419{
3420 unsigned long address = vmf->address, nr_pages, mask;
3421 pgoff_t start_pgoff = vmf->pgoff;
3422 pgoff_t end_pgoff;
3423 int off;
3424 vm_fault_t ret = 0;
3425
3426 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3427 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3428
3429 vmf->address = max(address & mask, vmf->vma->vm_start);
3430 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3431 start_pgoff -= off;
3432
3433 /*
3434 * end_pgoff is either the end of the page table, the end of
3435 * the vma or nr_pages from start_pgoff, depending what is nearest.
3436 */
3437 end_pgoff = start_pgoff -
3438 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3439 PTRS_PER_PTE - 1;
3440 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3441 start_pgoff + nr_pages - 1);
3442
3443 if (pmd_none(*vmf->pmd)) {
3444 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
3445 if (!vmf->prealloc_pte)
3446 goto out;
3447 smp_wmb(); /* See comment in __pte_alloc() */
3448 }
3449
3450 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3451
3452 /* Huge page is mapped? Page fault is solved */
3453 if (pmd_trans_huge(*vmf->pmd)) {
3454 ret = VM_FAULT_NOPAGE;
3455 goto out;
3456 }
3457
3458 /* ->map_pages() haven't done anything useful. Cold page cache? */
3459 if (!vmf->pte)
3460 goto out;
3461
3462 /* check if the page fault is solved */
3463 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3464 if (!pte_none(*vmf->pte))
3465 ret = VM_FAULT_NOPAGE;
3466 pte_unmap_unlock(vmf->pte, vmf->ptl);
3467out:
3468 vmf->address = address;
3469 vmf->pte = NULL;
3470 return ret;
3471}
3472
3473static vm_fault_t do_read_fault(struct vm_fault *vmf)
3474{
3475 struct vm_area_struct *vma = vmf->vma;
3476 vm_fault_t ret = 0;
3477
3478 /*
3479 * Let's call ->map_pages() first and use ->fault() as fallback
3480 * if page by the offset is not ready to be mapped (cold cache or
3481 * something).
3482 */
3483 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3484 ret = do_fault_around(vmf);
3485 if (ret)
3486 return ret;
3487 }
3488
3489 ret = __do_fault(vmf);
3490 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3491 return ret;
3492
3493 ret |= finish_fault(vmf);
3494 unlock_page(vmf->page);
3495 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3496 put_page(vmf->page);
3497 return ret;
3498}
3499
3500static vm_fault_t do_cow_fault(struct vm_fault *vmf)
3501{
3502 struct vm_area_struct *vma = vmf->vma;
3503 vm_fault_t ret;
3504
3505 if (unlikely(anon_vma_prepare(vma)))
3506 return VM_FAULT_OOM;
3507
3508 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3509 if (!vmf->cow_page)
3510 return VM_FAULT_OOM;
3511
3512 if (mem_cgroup_try_charge_delay(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3513 &vmf->memcg, false)) {
3514 put_page(vmf->cow_page);
3515 return VM_FAULT_OOM;
3516 }
3517
3518 ret = __do_fault(vmf);
3519 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3520 goto uncharge_out;
3521 if (ret & VM_FAULT_DONE_COW)
3522 return ret;
3523
3524 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3525 __SetPageUptodate(vmf->cow_page);
3526
3527 ret |= finish_fault(vmf);
3528 unlock_page(vmf->page);
3529 put_page(vmf->page);
3530 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3531 goto uncharge_out;
3532 return ret;
3533uncharge_out:
3534 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3535 put_page(vmf->cow_page);
3536 return ret;
3537}
3538
3539static vm_fault_t do_shared_fault(struct vm_fault *vmf)
3540{
3541 struct vm_area_struct *vma = vmf->vma;
3542 vm_fault_t ret, tmp;
3543
3544 ret = __do_fault(vmf);
3545 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3546 return ret;
3547
3548 /*
3549 * Check if the backing address space wants to know that the page is
3550 * about to become writable
3551 */
3552 if (vma->vm_ops->page_mkwrite) {
3553 unlock_page(vmf->page);
3554 tmp = do_page_mkwrite(vmf);
3555 if (unlikely(!tmp ||
3556 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3557 put_page(vmf->page);
3558 return tmp;
3559 }
3560 }
3561
3562 ret |= finish_fault(vmf);
3563 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3564 VM_FAULT_RETRY))) {
3565 unlock_page(vmf->page);
3566 put_page(vmf->page);
3567 return ret;
3568 }
3569
3570 fault_dirty_shared_page(vma, vmf->page);
3571 return ret;
3572}
3573
3574/*
3575 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3576 * but allow concurrent faults).
3577 * The mmap_sem may have been released depending on flags and our
3578 * return value. See filemap_fault() and __lock_page_or_retry().
3579 * If mmap_sem is released, vma may become invalid (for example
3580 * by other thread calling munmap()).
3581 */
3582static vm_fault_t do_fault(struct vm_fault *vmf)
3583{
3584 struct vm_area_struct *vma = vmf->vma;
3585 struct mm_struct *vm_mm = vma->vm_mm;
3586 vm_fault_t ret;
3587
3588 /*
3589 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
3590 */
3591 if (!vma->vm_ops->fault) {
3592 /*
3593 * If we find a migration pmd entry or a none pmd entry, which
3594 * should never happen, return SIGBUS
3595 */
3596 if (unlikely(!pmd_present(*vmf->pmd)))
3597 ret = VM_FAULT_SIGBUS;
3598 else {
3599 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
3600 vmf->pmd,
3601 vmf->address,
3602 &vmf->ptl);
3603 /*
3604 * Make sure this is not a temporary clearing of pte
3605 * by holding ptl and checking again. A R/M/W update
3606 * of pte involves: take ptl, clearing the pte so that
3607 * we don't have concurrent modification by hardware
3608 * followed by an update.
3609 */
3610 if (unlikely(pte_none(*vmf->pte)))
3611 ret = VM_FAULT_SIGBUS;
3612 else
3613 ret = VM_FAULT_NOPAGE;
3614
3615 pte_unmap_unlock(vmf->pte, vmf->ptl);
3616 }
3617 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
3618 ret = do_read_fault(vmf);
3619 else if (!(vma->vm_flags & VM_SHARED))
3620 ret = do_cow_fault(vmf);
3621 else
3622 ret = do_shared_fault(vmf);
3623
3624 /* preallocated pagetable is unused: free it */
3625 if (vmf->prealloc_pte) {
3626 pte_free(vm_mm, vmf->prealloc_pte);
3627 vmf->prealloc_pte = NULL;
3628 }
3629 return ret;
3630}
3631
3632static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3633 unsigned long addr, int page_nid,
3634 int *flags)
3635{
3636 get_page(page);
3637
3638 count_vm_numa_event(NUMA_HINT_FAULTS);
3639 if (page_nid == numa_node_id()) {
3640 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3641 *flags |= TNF_FAULT_LOCAL;
3642 }
3643
3644 return mpol_misplaced(page, vma, addr);
3645}
3646
3647static vm_fault_t do_numa_page(struct vm_fault *vmf)
3648{
3649 struct vm_area_struct *vma = vmf->vma;
3650 struct page *page = NULL;
3651 int page_nid = NUMA_NO_NODE;
3652 int last_cpupid;
3653 int target_nid;
3654 bool migrated = false;
3655 pte_t pte, old_pte;
3656 bool was_writable = pte_savedwrite(vmf->orig_pte);
3657 int flags = 0;
3658
3659 /*
3660 * The "pte" at this point cannot be used safely without
3661 * validation through pte_unmap_same(). It's of NUMA type but
3662 * the pfn may be screwed if the read is non atomic.
3663 */
3664 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3665 spin_lock(vmf->ptl);
3666 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3667 pte_unmap_unlock(vmf->pte, vmf->ptl);
3668 goto out;
3669 }
3670
3671 /*
3672 * Make it present again, Depending on how arch implementes non
3673 * accessible ptes, some can allow access by kernel mode.
3674 */
3675 old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
3676 pte = pte_modify(old_pte, vma->vm_page_prot);
3677 pte = pte_mkyoung(pte);
3678 if (was_writable)
3679 pte = pte_mkwrite(pte);
3680 ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
3681 update_mmu_cache(vma, vmf->address, vmf->pte);
3682
3683 page = vm_normal_page(vma, vmf->address, pte);
3684 if (!page) {
3685 pte_unmap_unlock(vmf->pte, vmf->ptl);
3686 return 0;
3687 }
3688
3689 /* TODO: handle PTE-mapped THP */
3690 if (PageCompound(page)) {
3691 pte_unmap_unlock(vmf->pte, vmf->ptl);
3692 return 0;
3693 }
3694
3695 /*
3696 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3697 * much anyway since they can be in shared cache state. This misses
3698 * the case where a mapping is writable but the process never writes
3699 * to it but pte_write gets cleared during protection updates and
3700 * pte_dirty has unpredictable behaviour between PTE scan updates,
3701 * background writeback, dirty balancing and application behaviour.
3702 */
3703 if (!pte_write(pte))
3704 flags |= TNF_NO_GROUP;
3705
3706 /*
3707 * Flag if the page is shared between multiple address spaces. This
3708 * is later used when determining whether to group tasks together
3709 */
3710 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3711 flags |= TNF_SHARED;
3712
3713 last_cpupid = page_cpupid_last(page);
3714 page_nid = page_to_nid(page);
3715 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3716 &flags);
3717 pte_unmap_unlock(vmf->pte, vmf->ptl);
3718 if (target_nid == NUMA_NO_NODE) {
3719 put_page(page);
3720 goto out;
3721 }
3722
3723 /* Migrate to the requested node */
3724 migrated = migrate_misplaced_page(page, vma, target_nid);
3725 if (migrated) {
3726 page_nid = target_nid;
3727 flags |= TNF_MIGRATED;
3728 } else
3729 flags |= TNF_MIGRATE_FAIL;
3730
3731out:
3732 if (page_nid != NUMA_NO_NODE)
3733 task_numa_fault(last_cpupid, page_nid, 1, flags);
3734 return 0;
3735}
3736
3737static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
3738{
3739 if (vma_is_anonymous(vmf->vma))
3740 return do_huge_pmd_anonymous_page(vmf);
3741 if (vmf->vma->vm_ops->huge_fault)
3742 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3743 return VM_FAULT_FALLBACK;
3744}
3745
3746/* `inline' is required to avoid gcc 4.1.2 build error */
3747static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3748{
3749 if (vma_is_anonymous(vmf->vma))
3750 return do_huge_pmd_wp_page(vmf, orig_pmd);
3751 if (vmf->vma->vm_ops->huge_fault)
3752 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3753
3754 /* COW handled on pte level: split pmd */
3755 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3756 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3757
3758 return VM_FAULT_FALLBACK;
3759}
3760
3761static inline bool vma_is_accessible(struct vm_area_struct *vma)
3762{
3763 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3764}
3765
3766static vm_fault_t create_huge_pud(struct vm_fault *vmf)
3767{
3768#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3769 /* No support for anonymous transparent PUD pages yet */
3770 if (vma_is_anonymous(vmf->vma))
3771 return VM_FAULT_FALLBACK;
3772 if (vmf->vma->vm_ops->huge_fault)
3773 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3774#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3775 return VM_FAULT_FALLBACK;
3776}
3777
3778static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3779{
3780#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3781 /* No support for anonymous transparent PUD pages yet */
3782 if (vma_is_anonymous(vmf->vma))
3783 return VM_FAULT_FALLBACK;
3784 if (vmf->vma->vm_ops->huge_fault)
3785 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3786#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3787 return VM_FAULT_FALLBACK;
3788}
3789
3790/*
3791 * These routines also need to handle stuff like marking pages dirty
3792 * and/or accessed for architectures that don't do it in hardware (most
3793 * RISC architectures). The early dirtying is also good on the i386.
3794 *
3795 * There is also a hook called "update_mmu_cache()" that architectures
3796 * with external mmu caches can use to update those (ie the Sparc or
3797 * PowerPC hashed page tables that act as extended TLBs).
3798 *
3799 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3800 * concurrent faults).
3801 *
3802 * The mmap_sem may have been released depending on flags and our return value.
3803 * See filemap_fault() and __lock_page_or_retry().
3804 */
3805static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
3806{
3807 pte_t entry;
3808
3809 if (unlikely(pmd_none(*vmf->pmd))) {
3810 /*
3811 * Leave __pte_alloc() until later: because vm_ops->fault may
3812 * want to allocate huge page, and if we expose page table
3813 * for an instant, it will be difficult to retract from
3814 * concurrent faults and from rmap lookups.
3815 */
3816 vmf->pte = NULL;
3817 } else {
3818 /* See comment in pte_alloc_one_map() */
3819 if (pmd_devmap_trans_unstable(vmf->pmd))
3820 return 0;
3821 /*
3822 * A regular pmd is established and it can't morph into a huge
3823 * pmd from under us anymore at this point because we hold the
3824 * mmap_sem read mode and khugepaged takes it in write mode.
3825 * So now it's safe to run pte_offset_map().
3826 */
3827 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3828 vmf->orig_pte = *vmf->pte;
3829
3830 /*
3831 * some architectures can have larger ptes than wordsize,
3832 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3833 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
3834 * accesses. The code below just needs a consistent view
3835 * for the ifs and we later double check anyway with the
3836 * ptl lock held. So here a barrier will do.
3837 */
3838 barrier();
3839 if (pte_none(vmf->orig_pte)) {
3840 pte_unmap(vmf->pte);
3841 vmf->pte = NULL;
3842 }
3843 }
3844
3845 if (!vmf->pte) {
3846 if (vma_is_anonymous(vmf->vma))
3847 return do_anonymous_page(vmf);
3848 else
3849 return do_fault(vmf);
3850 }
3851
3852 if (!pte_present(vmf->orig_pte))
3853 return do_swap_page(vmf);
3854
3855 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3856 return do_numa_page(vmf);
3857
3858 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3859 spin_lock(vmf->ptl);
3860 entry = vmf->orig_pte;
3861 if (unlikely(!pte_same(*vmf->pte, entry)))
3862 goto unlock;
3863 if (vmf->flags & FAULT_FLAG_WRITE) {
3864 if (!pte_write(entry))
3865 return do_wp_page(vmf);
3866 entry = pte_mkdirty(entry);
3867 }
3868 entry = pte_mkyoung(entry);
3869 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3870 vmf->flags & FAULT_FLAG_WRITE)) {
3871 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3872 } else {
3873 /*
3874 * This is needed only for protection faults but the arch code
3875 * is not yet telling us if this is a protection fault or not.
3876 * This still avoids useless tlb flushes for .text page faults
3877 * with threads.
3878 */
3879 if (vmf->flags & FAULT_FLAG_WRITE)
3880 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3881 }
3882unlock:
3883 pte_unmap_unlock(vmf->pte, vmf->ptl);
3884 return 0;
3885}
3886
3887/*
3888 * By the time we get here, we already hold the mm semaphore
3889 *
3890 * The mmap_sem may have been released depending on flags and our
3891 * return value. See filemap_fault() and __lock_page_or_retry().
3892 */
3893static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
3894 unsigned long address, unsigned int flags)
3895{
3896 struct vm_fault vmf = {
3897 .vma = vma,
3898 .address = address & PAGE_MASK,
3899 .flags = flags,
3900 .pgoff = linear_page_index(vma, address),
3901 .gfp_mask = __get_fault_gfp_mask(vma),
3902 };
3903 unsigned int dirty = flags & FAULT_FLAG_WRITE;
3904 struct mm_struct *mm = vma->vm_mm;
3905 pgd_t *pgd;
3906 p4d_t *p4d;
3907 vm_fault_t ret;
3908
3909 pgd = pgd_offset(mm, address);
3910 p4d = p4d_alloc(mm, pgd, address);
3911 if (!p4d)
3912 return VM_FAULT_OOM;
3913
3914 vmf.pud = pud_alloc(mm, p4d, address);
3915 if (!vmf.pud)
3916 return VM_FAULT_OOM;
3917 if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) {
3918 ret = create_huge_pud(&vmf);
3919 if (!(ret & VM_FAULT_FALLBACK))
3920 return ret;
3921 } else {
3922 pud_t orig_pud = *vmf.pud;
3923
3924 barrier();
3925 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
3926
3927 /* NUMA case for anonymous PUDs would go here */
3928
3929 if (dirty && !pud_write(orig_pud)) {
3930 ret = wp_huge_pud(&vmf, orig_pud);
3931 if (!(ret & VM_FAULT_FALLBACK))
3932 return ret;
3933 } else {
3934 huge_pud_set_accessed(&vmf, orig_pud);
3935 return 0;
3936 }
3937 }
3938 }
3939
3940 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
3941 if (!vmf.pmd)
3942 return VM_FAULT_OOM;
3943 if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) {
3944 ret = create_huge_pmd(&vmf);
3945 if (!(ret & VM_FAULT_FALLBACK))
3946 return ret;
3947 } else {
3948 pmd_t orig_pmd = *vmf.pmd;
3949
3950 barrier();
3951 if (unlikely(is_swap_pmd(orig_pmd))) {
3952 VM_BUG_ON(thp_migration_supported() &&
3953 !is_pmd_migration_entry(orig_pmd));
3954 if (is_pmd_migration_entry(orig_pmd))
3955 pmd_migration_entry_wait(mm, vmf.pmd);
3956 return 0;
3957 }
3958 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3959 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
3960 return do_huge_pmd_numa_page(&vmf, orig_pmd);
3961
3962 if (dirty && !pmd_write(orig_pmd)) {
3963 ret = wp_huge_pmd(&vmf, orig_pmd);
3964 if (!(ret & VM_FAULT_FALLBACK))
3965 return ret;
3966 } else {
3967 huge_pmd_set_accessed(&vmf, orig_pmd);
3968 return 0;
3969 }
3970 }
3971 }
3972
3973 return handle_pte_fault(&vmf);
3974}
3975
3976/*
3977 * By the time we get here, we already hold the mm semaphore
3978 *
3979 * The mmap_sem may have been released depending on flags and our
3980 * return value. See filemap_fault() and __lock_page_or_retry().
3981 */
3982vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3983 unsigned int flags)
3984{
3985 vm_fault_t ret;
3986
3987 __set_current_state(TASK_RUNNING);
3988
3989 count_vm_event(PGFAULT);
3990 count_memcg_event_mm(vma->vm_mm, PGFAULT);
3991
3992 /* do counter updates before entering really critical section. */
3993 check_sync_rss_stat(current);
3994
3995 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3996 flags & FAULT_FLAG_INSTRUCTION,
3997 flags & FAULT_FLAG_REMOTE))
3998 return VM_FAULT_SIGSEGV;
3999
4000 /*
4001 * Enable the memcg OOM handling for faults triggered in user
4002 * space. Kernel faults are handled more gracefully.
4003 */
4004 if (flags & FAULT_FLAG_USER)
4005 mem_cgroup_enter_user_fault();
4006
4007 if (unlikely(is_vm_hugetlb_page(vma)))
4008 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4009 else
4010 ret = __handle_mm_fault(vma, address, flags);
4011
4012 if (flags & FAULT_FLAG_USER) {
4013 mem_cgroup_exit_user_fault();
4014 /*
4015 * The task may have entered a memcg OOM situation but
4016 * if the allocation error was handled gracefully (no
4017 * VM_FAULT_OOM), there is no need to kill anything.
4018 * Just clean up the OOM state peacefully.
4019 */
4020 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4021 mem_cgroup_oom_synchronize(false);
4022 }
4023
4024 return ret;
4025}
4026EXPORT_SYMBOL_GPL(handle_mm_fault);
4027
4028#ifndef __PAGETABLE_P4D_FOLDED
4029/*
4030 * Allocate p4d page table.
4031 * We've already handled the fast-path in-line.
4032 */
4033int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4034{
4035 p4d_t *new = p4d_alloc_one(mm, address);
4036 if (!new)
4037 return -ENOMEM;
4038
4039 smp_wmb(); /* See comment in __pte_alloc */
4040
4041 spin_lock(&mm->page_table_lock);
4042 if (pgd_present(*pgd)) /* Another has populated it */
4043 p4d_free(mm, new);
4044 else
4045 pgd_populate(mm, pgd, new);
4046 spin_unlock(&mm->page_table_lock);
4047 return 0;
4048}
4049#endif /* __PAGETABLE_P4D_FOLDED */
4050
4051#ifndef __PAGETABLE_PUD_FOLDED
4052/*
4053 * Allocate page upper directory.
4054 * We've already handled the fast-path in-line.
4055 */
4056int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4057{
4058 pud_t *new = pud_alloc_one(mm, address);
4059 if (!new)
4060 return -ENOMEM;
4061
4062 smp_wmb(); /* See comment in __pte_alloc */
4063
4064 spin_lock(&mm->page_table_lock);
4065#ifndef __ARCH_HAS_5LEVEL_HACK
4066 if (!p4d_present(*p4d)) {
4067 mm_inc_nr_puds(mm);
4068 p4d_populate(mm, p4d, new);
4069 } else /* Another has populated it */
4070 pud_free(mm, new);
4071#else
4072 if (!pgd_present(*p4d)) {
4073 mm_inc_nr_puds(mm);
4074 pgd_populate(mm, p4d, new);
4075 } else /* Another has populated it */
4076 pud_free(mm, new);
4077#endif /* __ARCH_HAS_5LEVEL_HACK */
4078 spin_unlock(&mm->page_table_lock);
4079 return 0;
4080}
4081#endif /* __PAGETABLE_PUD_FOLDED */
4082
4083#ifndef __PAGETABLE_PMD_FOLDED
4084/*
4085 * Allocate page middle directory.
4086 * We've already handled the fast-path in-line.
4087 */
4088int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4089{
4090 spinlock_t *ptl;
4091 pmd_t *new = pmd_alloc_one(mm, address);
4092 if (!new)
4093 return -ENOMEM;
4094
4095 smp_wmb(); /* See comment in __pte_alloc */
4096
4097 ptl = pud_lock(mm, pud);
4098#ifndef __ARCH_HAS_4LEVEL_HACK
4099 if (!pud_present(*pud)) {
4100 mm_inc_nr_pmds(mm);
4101 pud_populate(mm, pud, new);
4102 } else /* Another has populated it */
4103 pmd_free(mm, new);
4104#else
4105 if (!pgd_present(*pud)) {
4106 mm_inc_nr_pmds(mm);
4107 pgd_populate(mm, pud, new);
4108 } else /* Another has populated it */
4109 pmd_free(mm, new);
4110#endif /* __ARCH_HAS_4LEVEL_HACK */
4111 spin_unlock(ptl);
4112 return 0;
4113}
4114#endif /* __PAGETABLE_PMD_FOLDED */
4115
4116static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4117 struct mmu_notifier_range *range,
4118 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4119{
4120 pgd_t *pgd;
4121 p4d_t *p4d;
4122 pud_t *pud;
4123 pmd_t *pmd;
4124 pte_t *ptep;
4125
4126 pgd = pgd_offset(mm, address);
4127 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4128 goto out;
4129
4130 p4d = p4d_offset(pgd, address);
4131 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4132 goto out;
4133
4134 pud = pud_offset(p4d, address);
4135 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4136 goto out;
4137
4138 pmd = pmd_offset(pud, address);
4139 VM_BUG_ON(pmd_trans_huge(*pmd));
4140
4141 if (pmd_huge(*pmd)) {
4142 if (!pmdpp)
4143 goto out;
4144
4145 if (range) {
4146 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0,
4147 NULL, mm, address & PMD_MASK,
4148 (address & PMD_MASK) + PMD_SIZE);
4149 mmu_notifier_invalidate_range_start(range);
4150 }
4151 *ptlp = pmd_lock(mm, pmd);
4152 if (pmd_huge(*pmd)) {
4153 *pmdpp = pmd;
4154 return 0;
4155 }
4156 spin_unlock(*ptlp);
4157 if (range)
4158 mmu_notifier_invalidate_range_end(range);
4159 }
4160
4161 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4162 goto out;
4163
4164 if (range) {
4165 mmu_notifier_range_init(range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
4166 address & PAGE_MASK,
4167 (address & PAGE_MASK) + PAGE_SIZE);
4168 mmu_notifier_invalidate_range_start(range);
4169 }
4170 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4171 if (!pte_present(*ptep))
4172 goto unlock;
4173 *ptepp = ptep;
4174 return 0;
4175unlock:
4176 pte_unmap_unlock(ptep, *ptlp);
4177 if (range)
4178 mmu_notifier_invalidate_range_end(range);
4179out:
4180 return -EINVAL;
4181}
4182
4183static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4184 pte_t **ptepp, spinlock_t **ptlp)
4185{
4186 int res;
4187
4188 /* (void) is needed to make gcc happy */
4189 (void) __cond_lock(*ptlp,
4190 !(res = __follow_pte_pmd(mm, address, NULL,
4191 ptepp, NULL, ptlp)));
4192 return res;
4193}
4194
4195int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4196 struct mmu_notifier_range *range,
4197 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4198{
4199 int res;
4200
4201 /* (void) is needed to make gcc happy */
4202 (void) __cond_lock(*ptlp,
4203 !(res = __follow_pte_pmd(mm, address, range,
4204 ptepp, pmdpp, ptlp)));
4205 return res;
4206}
4207EXPORT_SYMBOL(follow_pte_pmd);
4208
4209/**
4210 * follow_pfn - look up PFN at a user virtual address
4211 * @vma: memory mapping
4212 * @address: user virtual address
4213 * @pfn: location to store found PFN
4214 *
4215 * Only IO mappings and raw PFN mappings are allowed.
4216 *
4217 * Return: zero and the pfn at @pfn on success, -ve otherwise.
4218 */
4219int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4220 unsigned long *pfn)
4221{
4222 int ret = -EINVAL;
4223 spinlock_t *ptl;
4224 pte_t *ptep;
4225
4226 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4227 return ret;
4228
4229 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4230 if (ret)
4231 return ret;
4232 *pfn = pte_pfn(*ptep);
4233 pte_unmap_unlock(ptep, ptl);
4234 return 0;
4235}
4236EXPORT_SYMBOL(follow_pfn);
4237
4238#ifdef CONFIG_HAVE_IOREMAP_PROT
4239int follow_phys(struct vm_area_struct *vma,
4240 unsigned long address, unsigned int flags,
4241 unsigned long *prot, resource_size_t *phys)
4242{
4243 int ret = -EINVAL;
4244 pte_t *ptep, pte;
4245 spinlock_t *ptl;
4246
4247 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4248 goto out;
4249
4250 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4251 goto out;
4252 pte = *ptep;
4253
4254 if ((flags & FOLL_WRITE) && !pte_write(pte))
4255 goto unlock;
4256
4257 *prot = pgprot_val(pte_pgprot(pte));
4258 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4259
4260 ret = 0;
4261unlock:
4262 pte_unmap_unlock(ptep, ptl);
4263out:
4264 return ret;
4265}
4266
4267int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4268 void *buf, int len, int write)
4269{
4270 resource_size_t phys_addr;
4271 unsigned long prot = 0;
4272 void __iomem *maddr;
4273 int offset = addr & (PAGE_SIZE-1);
4274
4275 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4276 return -EINVAL;
4277
4278 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4279 if (!maddr)
4280 return -ENOMEM;
4281
4282 if (write)
4283 memcpy_toio(maddr + offset, buf, len);
4284 else
4285 memcpy_fromio(buf, maddr + offset, len);
4286 iounmap(maddr);
4287
4288 return len;
4289}
4290EXPORT_SYMBOL_GPL(generic_access_phys);
4291#endif
4292
4293/*
4294 * Access another process' address space as given in mm. If non-NULL, use the
4295 * given task for page fault accounting.
4296 */
4297int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4298 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4299{
4300 struct vm_area_struct *vma;
4301 void *old_buf = buf;
4302 int write = gup_flags & FOLL_WRITE;
4303
4304 if (down_read_killable(&mm->mmap_sem))
4305 return 0;
4306
4307 /* ignore errors, just check how much was successfully transferred */
4308 while (len) {
4309 int bytes, ret, offset;
4310 void *maddr;
4311 struct page *page = NULL;
4312
4313 ret = get_user_pages_remote(tsk, mm, addr, 1,
4314 gup_flags, &page, &vma, NULL);
4315 if (ret <= 0) {
4316#ifndef CONFIG_HAVE_IOREMAP_PROT
4317 break;
4318#else
4319 /*
4320 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4321 * we can access using slightly different code.
4322 */
4323 vma = find_vma(mm, addr);
4324 if (!vma || vma->vm_start > addr)
4325 break;
4326 if (vma->vm_ops && vma->vm_ops->access)
4327 ret = vma->vm_ops->access(vma, addr, buf,
4328 len, write);
4329 if (ret <= 0)
4330 break;
4331 bytes = ret;
4332#endif
4333 } else {
4334 bytes = len;
4335 offset = addr & (PAGE_SIZE-1);
4336 if (bytes > PAGE_SIZE-offset)
4337 bytes = PAGE_SIZE-offset;
4338
4339 maddr = kmap(page);
4340 if (write) {
4341 copy_to_user_page(vma, page, addr,
4342 maddr + offset, buf, bytes);
4343 set_page_dirty_lock(page);
4344 } else {
4345 copy_from_user_page(vma, page, addr,
4346 buf, maddr + offset, bytes);
4347 }
4348 kunmap(page);
4349 put_page(page);
4350 }
4351 len -= bytes;
4352 buf += bytes;
4353 addr += bytes;
4354 }
4355 up_read(&mm->mmap_sem);
4356
4357 return buf - old_buf;
4358}
4359
4360/**
4361 * access_remote_vm - access another process' address space
4362 * @mm: the mm_struct of the target address space
4363 * @addr: start address to access
4364 * @buf: source or destination buffer
4365 * @len: number of bytes to transfer
4366 * @gup_flags: flags modifying lookup behaviour
4367 *
4368 * The caller must hold a reference on @mm.
4369 *
4370 * Return: number of bytes copied from source to destination.
4371 */
4372int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4373 void *buf, int len, unsigned int gup_flags)
4374{
4375 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4376}
4377
4378/*
4379 * Access another process' address space.
4380 * Source/target buffer must be kernel space,
4381 * Do not walk the page table directly, use get_user_pages
4382 */
4383int access_process_vm(struct task_struct *tsk, unsigned long addr,
4384 void *buf, int len, unsigned int gup_flags)
4385{
4386 struct mm_struct *mm;
4387 int ret;
4388
4389 mm = get_task_mm(tsk);
4390 if (!mm)
4391 return 0;
4392
4393 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4394
4395 mmput(mm);
4396
4397 return ret;
4398}
4399EXPORT_SYMBOL_GPL(access_process_vm);
4400
4401/*
4402 * Print the name of a VMA.
4403 */
4404void print_vma_addr(char *prefix, unsigned long ip)
4405{
4406 struct mm_struct *mm = current->mm;
4407 struct vm_area_struct *vma;
4408
4409 /*
4410 * we might be running from an atomic context so we cannot sleep
4411 */
4412 if (!down_read_trylock(&mm->mmap_sem))
4413 return;
4414
4415 vma = find_vma(mm, ip);
4416 if (vma && vma->vm_file) {
4417 struct file *f = vma->vm_file;
4418 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4419 if (buf) {
4420 char *p;
4421
4422 p = file_path(f, buf, PAGE_SIZE);
4423 if (IS_ERR(p))
4424 p = "?";
4425 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4426 vma->vm_start,
4427 vma->vm_end - vma->vm_start);
4428 free_page((unsigned long)buf);
4429 }
4430 }
4431 up_read(&mm->mmap_sem);
4432}
4433
4434#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4435void __might_fault(const char *file, int line)
4436{
4437 /*
4438 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4439 * holding the mmap_sem, this is safe because kernel memory doesn't
4440 * get paged out, therefore we'll never actually fault, and the
4441 * below annotations will generate false positives.
4442 */
4443 if (uaccess_kernel())
4444 return;
4445 if (pagefault_disabled())
4446 return;
4447 __might_sleep(file, line, 0);
4448#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4449 if (current->mm)
4450 might_lock_read(¤t->mm->mmap_sem);
4451#endif
4452}
4453EXPORT_SYMBOL(__might_fault);
4454#endif
4455
4456#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4457/*
4458 * Process all subpages of the specified huge page with the specified
4459 * operation. The target subpage will be processed last to keep its
4460 * cache lines hot.
4461 */
4462static inline void process_huge_page(
4463 unsigned long addr_hint, unsigned int pages_per_huge_page,
4464 void (*process_subpage)(unsigned long addr, int idx, void *arg),
4465 void *arg)
4466{
4467 int i, n, base, l;
4468 unsigned long addr = addr_hint &
4469 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4470
4471 /* Process target subpage last to keep its cache lines hot */
4472 might_sleep();
4473 n = (addr_hint - addr) / PAGE_SIZE;
4474 if (2 * n <= pages_per_huge_page) {
4475 /* If target subpage in first half of huge page */
4476 base = 0;
4477 l = n;
4478 /* Process subpages at the end of huge page */
4479 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4480 cond_resched();
4481 process_subpage(addr + i * PAGE_SIZE, i, arg);
4482 }
4483 } else {
4484 /* If target subpage in second half of huge page */
4485 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4486 l = pages_per_huge_page - n;
4487 /* Process subpages at the begin of huge page */
4488 for (i = 0; i < base; i++) {
4489 cond_resched();
4490 process_subpage(addr + i * PAGE_SIZE, i, arg);
4491 }
4492 }
4493 /*
4494 * Process remaining subpages in left-right-left-right pattern
4495 * towards the target subpage
4496 */
4497 for (i = 0; i < l; i++) {
4498 int left_idx = base + i;
4499 int right_idx = base + 2 * l - 1 - i;
4500
4501 cond_resched();
4502 process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
4503 cond_resched();
4504 process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
4505 }
4506}
4507
4508static void clear_gigantic_page(struct page *page,
4509 unsigned long addr,
4510 unsigned int pages_per_huge_page)
4511{
4512 int i;
4513 struct page *p = page;
4514
4515 might_sleep();
4516 for (i = 0; i < pages_per_huge_page;
4517 i++, p = mem_map_next(p, page, i)) {
4518 cond_resched();
4519 clear_user_highpage(p, addr + i * PAGE_SIZE);
4520 }
4521}
4522
4523static void clear_subpage(unsigned long addr, int idx, void *arg)
4524{
4525 struct page *page = arg;
4526
4527 clear_user_highpage(page + idx, addr);
4528}
4529
4530void clear_huge_page(struct page *page,
4531 unsigned long addr_hint, unsigned int pages_per_huge_page)
4532{
4533 unsigned long addr = addr_hint &
4534 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4535
4536 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4537 clear_gigantic_page(page, addr, pages_per_huge_page);
4538 return;
4539 }
4540
4541 process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
4542}
4543
4544static void copy_user_gigantic_page(struct page *dst, struct page *src,
4545 unsigned long addr,
4546 struct vm_area_struct *vma,
4547 unsigned int pages_per_huge_page)
4548{
4549 int i;
4550 struct page *dst_base = dst;
4551 struct page *src_base = src;
4552
4553 for (i = 0; i < pages_per_huge_page; ) {
4554 cond_resched();
4555 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4556
4557 i++;
4558 dst = mem_map_next(dst, dst_base, i);
4559 src = mem_map_next(src, src_base, i);
4560 }
4561}
4562
4563struct copy_subpage_arg {
4564 struct page *dst;
4565 struct page *src;
4566 struct vm_area_struct *vma;
4567};
4568
4569static void copy_subpage(unsigned long addr, int idx, void *arg)
4570{
4571 struct copy_subpage_arg *copy_arg = arg;
4572
4573 copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
4574 addr, copy_arg->vma);
4575}
4576
4577void copy_user_huge_page(struct page *dst, struct page *src,
4578 unsigned long addr_hint, struct vm_area_struct *vma,
4579 unsigned int pages_per_huge_page)
4580{
4581 unsigned long addr = addr_hint &
4582 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4583 struct copy_subpage_arg arg = {
4584 .dst = dst,
4585 .src = src,
4586 .vma = vma,
4587 };
4588
4589 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4590 copy_user_gigantic_page(dst, src, addr, vma,
4591 pages_per_huge_page);
4592 return;
4593 }
4594
4595 process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
4596}
4597
4598long copy_huge_page_from_user(struct page *dst_page,
4599 const void __user *usr_src,
4600 unsigned int pages_per_huge_page,
4601 bool allow_pagefault)
4602{
4603 void *src = (void *)usr_src;
4604 void *page_kaddr;
4605 unsigned long i, rc = 0;
4606 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4607
4608 for (i = 0; i < pages_per_huge_page; i++) {
4609 if (allow_pagefault)
4610 page_kaddr = kmap(dst_page + i);
4611 else
4612 page_kaddr = kmap_atomic(dst_page + i);
4613 rc = copy_from_user(page_kaddr,
4614 (const void __user *)(src + i * PAGE_SIZE),
4615 PAGE_SIZE);
4616 if (allow_pagefault)
4617 kunmap(dst_page + i);
4618 else
4619 kunmap_atomic(page_kaddr);
4620
4621 ret_val -= (PAGE_SIZE - rc);
4622 if (rc)
4623 break;
4624
4625 cond_resched();
4626 }
4627 return ret_val;
4628}
4629#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4630
4631#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4632
4633static struct kmem_cache *page_ptl_cachep;
4634
4635void __init ptlock_cache_init(void)
4636{
4637 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4638 SLAB_PANIC, NULL);
4639}
4640
4641bool ptlock_alloc(struct page *page)
4642{
4643 spinlock_t *ptl;
4644
4645 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4646 if (!ptl)
4647 return false;
4648 page->ptl = ptl;
4649 return true;
4650}
4651
4652void ptlock_free(struct page *page)
4653{
4654 kmem_cache_free(page_ptl_cachep, page->ptl);
4655}
4656#endif
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 */