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