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