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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 pgprot_t pgprot = vma->vm_page_prot;
1653
1654 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1655
1656 if (addr < vma->vm_start || addr >= vma->vm_end)
1657 return -EFAULT;
1658 if (track_pfn_insert(vma, &pgprot, pfn))
1659 return -EINVAL;
1660
1661 /*
1662 * If we don't have pte special, then we have to use the pfn_valid()
1663 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1664 * refcount the page if pfn_valid is true (hence insert_page rather
1665 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1666 * without pte special, it would there be refcounted as a normal page.
1667 */
1668 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1669 struct page *page;
1670
1671 /*
1672 * At this point we are committed to insert_page()
1673 * regardless of whether the caller specified flags that
1674 * result in pfn_t_has_page() == false.
1675 */
1676 page = pfn_to_page(pfn_t_to_pfn(pfn));
1677 return insert_page(vma, addr, page, pgprot);
1678 }
1679 return insert_pfn(vma, addr, pfn, pgprot);
1680 }
1681 EXPORT_SYMBOL(vm_insert_mixed);
1682
1683 /*
1684 * maps a range of physical memory into the requested pages. the old
1685 * mappings are removed. any references to nonexistent pages results
1686 * in null mappings (currently treated as "copy-on-access")
1687 */
1688 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1689 unsigned long addr, unsigned long end,
1690 unsigned long pfn, pgprot_t prot)
1691 {
1692 pte_t *pte;
1693 spinlock_t *ptl;
1694
1695 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1696 if (!pte)
1697 return -ENOMEM;
1698 arch_enter_lazy_mmu_mode();
1699 do {
1700 BUG_ON(!pte_none(*pte));
1701 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1702 pfn++;
1703 } while (pte++, addr += PAGE_SIZE, addr != end);
1704 arch_leave_lazy_mmu_mode();
1705 pte_unmap_unlock(pte - 1, ptl);
1706 return 0;
1707 }
1708
1709 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1710 unsigned long addr, unsigned long end,
1711 unsigned long pfn, pgprot_t prot)
1712 {
1713 pmd_t *pmd;
1714 unsigned long next;
1715
1716 pfn -= addr >> PAGE_SHIFT;
1717 pmd = pmd_alloc(mm, pud, addr);
1718 if (!pmd)
1719 return -ENOMEM;
1720 VM_BUG_ON(pmd_trans_huge(*pmd));
1721 do {
1722 next = pmd_addr_end(addr, end);
1723 if (remap_pte_range(mm, pmd, addr, next,
1724 pfn + (addr >> PAGE_SHIFT), prot))
1725 return -ENOMEM;
1726 } while (pmd++, addr = next, addr != end);
1727 return 0;
1728 }
1729
1730 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1731 unsigned long addr, unsigned long end,
1732 unsigned long pfn, pgprot_t prot)
1733 {
1734 pud_t *pud;
1735 unsigned long next;
1736
1737 pfn -= addr >> PAGE_SHIFT;
1738 pud = pud_alloc(mm, pgd, addr);
1739 if (!pud)
1740 return -ENOMEM;
1741 do {
1742 next = pud_addr_end(addr, end);
1743 if (remap_pmd_range(mm, pud, addr, next,
1744 pfn + (addr >> PAGE_SHIFT), prot))
1745 return -ENOMEM;
1746 } while (pud++, addr = next, addr != end);
1747 return 0;
1748 }
1749
1750 /**
1751 * remap_pfn_range - remap kernel memory to userspace
1752 * @vma: user vma to map to
1753 * @addr: target user address to start at
1754 * @pfn: physical address of kernel memory
1755 * @size: size of map area
1756 * @prot: page protection flags for this mapping
1757 *
1758 * Note: this is only safe if the mm semaphore is held when called.
1759 */
1760 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1761 unsigned long pfn, unsigned long size, pgprot_t prot)
1762 {
1763 pgd_t *pgd;
1764 unsigned long next;
1765 unsigned long end = addr + PAGE_ALIGN(size);
1766 struct mm_struct *mm = vma->vm_mm;
1767 unsigned long remap_pfn = pfn;
1768 int err;
1769
1770 /*
1771 * Physically remapped pages are special. Tell the
1772 * rest of the world about it:
1773 * VM_IO tells people not to look at these pages
1774 * (accesses can have side effects).
1775 * VM_PFNMAP tells the core MM that the base pages are just
1776 * raw PFN mappings, and do not have a "struct page" associated
1777 * with them.
1778 * VM_DONTEXPAND
1779 * Disable vma merging and expanding with mremap().
1780 * VM_DONTDUMP
1781 * Omit vma from core dump, even when VM_IO turned off.
1782 *
1783 * There's a horrible special case to handle copy-on-write
1784 * behaviour that some programs depend on. We mark the "original"
1785 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1786 * See vm_normal_page() for details.
1787 */
1788 if (is_cow_mapping(vma->vm_flags)) {
1789 if (addr != vma->vm_start || end != vma->vm_end)
1790 return -EINVAL;
1791 vma->vm_pgoff = pfn;
1792 }
1793
1794 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1795 if (err)
1796 return -EINVAL;
1797
1798 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1799
1800 BUG_ON(addr >= end);
1801 pfn -= addr >> PAGE_SHIFT;
1802 pgd = pgd_offset(mm, addr);
1803 flush_cache_range(vma, addr, end);
1804 do {
1805 next = pgd_addr_end(addr, end);
1806 err = remap_pud_range(mm, pgd, addr, next,
1807 pfn + (addr >> PAGE_SHIFT), prot);
1808 if (err)
1809 break;
1810 } while (pgd++, addr = next, addr != end);
1811
1812 if (err)
1813 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1814
1815 return err;
1816 }
1817 EXPORT_SYMBOL(remap_pfn_range);
1818
1819 /**
1820 * vm_iomap_memory - remap memory to userspace
1821 * @vma: user vma to map to
1822 * @start: start of area
1823 * @len: size of area
1824 *
1825 * This is a simplified io_remap_pfn_range() for common driver use. The
1826 * driver just needs to give us the physical memory range to be mapped,
1827 * we'll figure out the rest from the vma information.
1828 *
1829 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1830 * whatever write-combining details or similar.
1831 */
1832 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1833 {
1834 unsigned long vm_len, pfn, pages;
1835
1836 /* Check that the physical memory area passed in looks valid */
1837 if (start + len < start)
1838 return -EINVAL;
1839 /*
1840 * You *really* shouldn't map things that aren't page-aligned,
1841 * but we've historically allowed it because IO memory might
1842 * just have smaller alignment.
1843 */
1844 len += start & ~PAGE_MASK;
1845 pfn = start >> PAGE_SHIFT;
1846 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1847 if (pfn + pages < pfn)
1848 return -EINVAL;
1849
1850 /* We start the mapping 'vm_pgoff' pages into the area */
1851 if (vma->vm_pgoff > pages)
1852 return -EINVAL;
1853 pfn += vma->vm_pgoff;
1854 pages -= vma->vm_pgoff;
1855
1856 /* Can we fit all of the mapping? */
1857 vm_len = vma->vm_end - vma->vm_start;
1858 if (vm_len >> PAGE_SHIFT > pages)
1859 return -EINVAL;
1860
1861 /* Ok, let it rip */
1862 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1863 }
1864 EXPORT_SYMBOL(vm_iomap_memory);
1865
1866 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1867 unsigned long addr, unsigned long end,
1868 pte_fn_t fn, void *data)
1869 {
1870 pte_t *pte;
1871 int err;
1872 pgtable_t token;
1873 spinlock_t *uninitialized_var(ptl);
1874
1875 pte = (mm == &init_mm) ?
1876 pte_alloc_kernel(pmd, addr) :
1877 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1878 if (!pte)
1879 return -ENOMEM;
1880
1881 BUG_ON(pmd_huge(*pmd));
1882
1883 arch_enter_lazy_mmu_mode();
1884
1885 token = pmd_pgtable(*pmd);
1886
1887 do {
1888 err = fn(pte++, token, addr, data);
1889 if (err)
1890 break;
1891 } while (addr += PAGE_SIZE, addr != end);
1892
1893 arch_leave_lazy_mmu_mode();
1894
1895 if (mm != &init_mm)
1896 pte_unmap_unlock(pte-1, ptl);
1897 return err;
1898 }
1899
1900 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1901 unsigned long addr, unsigned long end,
1902 pte_fn_t fn, void *data)
1903 {
1904 pmd_t *pmd;
1905 unsigned long next;
1906 int err;
1907
1908 BUG_ON(pud_huge(*pud));
1909
1910 pmd = pmd_alloc(mm, pud, addr);
1911 if (!pmd)
1912 return -ENOMEM;
1913 do {
1914 next = pmd_addr_end(addr, end);
1915 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1916 if (err)
1917 break;
1918 } while (pmd++, addr = next, addr != end);
1919 return err;
1920 }
1921
1922 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1923 unsigned long addr, unsigned long end,
1924 pte_fn_t fn, void *data)
1925 {
1926 pud_t *pud;
1927 unsigned long next;
1928 int err;
1929
1930 pud = pud_alloc(mm, pgd, addr);
1931 if (!pud)
1932 return -ENOMEM;
1933 do {
1934 next = pud_addr_end(addr, end);
1935 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1936 if (err)
1937 break;
1938 } while (pud++, addr = next, addr != end);
1939 return err;
1940 }
1941
1942 /*
1943 * Scan a region of virtual memory, filling in page tables as necessary
1944 * and calling a provided function on each leaf page table.
1945 */
1946 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1947 unsigned long size, pte_fn_t fn, void *data)
1948 {
1949 pgd_t *pgd;
1950 unsigned long next;
1951 unsigned long end = addr + size;
1952 int err;
1953
1954 if (WARN_ON(addr >= end))
1955 return -EINVAL;
1956
1957 pgd = pgd_offset(mm, addr);
1958 do {
1959 next = pgd_addr_end(addr, end);
1960 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1961 if (err)
1962 break;
1963 } while (pgd++, addr = next, addr != end);
1964
1965 return err;
1966 }
1967 EXPORT_SYMBOL_GPL(apply_to_page_range);
1968
1969 /*
1970 * handle_pte_fault chooses page fault handler according to an entry which was
1971 * read non-atomically. Before making any commitment, on those architectures
1972 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
1973 * parts, do_swap_page must check under lock before unmapping the pte and
1974 * proceeding (but do_wp_page is only called after already making such a check;
1975 * and do_anonymous_page can safely check later on).
1976 */
1977 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1978 pte_t *page_table, pte_t orig_pte)
1979 {
1980 int same = 1;
1981 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1982 if (sizeof(pte_t) > sizeof(unsigned long)) {
1983 spinlock_t *ptl = pte_lockptr(mm, pmd);
1984 spin_lock(ptl);
1985 same = pte_same(*page_table, orig_pte);
1986 spin_unlock(ptl);
1987 }
1988 #endif
1989 pte_unmap(page_table);
1990 return same;
1991 }
1992
1993 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1994 {
1995 debug_dma_assert_idle(src);
1996
1997 /*
1998 * If the source page was a PFN mapping, we don't have
1999 * a "struct page" for it. We do a best-effort copy by
2000 * just copying from the original user address. If that
2001 * fails, we just zero-fill it. Live with it.
2002 */
2003 if (unlikely(!src)) {
2004 void *kaddr = kmap_atomic(dst);
2005 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2006
2007 /*
2008 * This really shouldn't fail, because the page is there
2009 * in the page tables. But it might just be unreadable,
2010 * in which case we just give up and fill the result with
2011 * zeroes.
2012 */
2013 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2014 clear_page(kaddr);
2015 kunmap_atomic(kaddr);
2016 flush_dcache_page(dst);
2017 } else
2018 copy_user_highpage(dst, src, va, vma);
2019 }
2020
2021 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2022 {
2023 struct file *vm_file = vma->vm_file;
2024
2025 if (vm_file)
2026 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2027
2028 /*
2029 * Special mappings (e.g. VDSO) do not have any file so fake
2030 * a default GFP_KERNEL for them.
2031 */
2032 return GFP_KERNEL;
2033 }
2034
2035 /*
2036 * Notify the address space that the page is about to become writable so that
2037 * it can prohibit this or wait for the page to get into an appropriate state.
2038 *
2039 * We do this without the lock held, so that it can sleep if it needs to.
2040 */
2041 static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
2042 unsigned long address)
2043 {
2044 struct vm_fault vmf;
2045 int ret;
2046
2047 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2048 vmf.pgoff = page->index;
2049 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2050 vmf.gfp_mask = __get_fault_gfp_mask(vma);
2051 vmf.page = page;
2052 vmf.cow_page = NULL;
2053
2054 ret = vma->vm_ops->page_mkwrite(vma, &vmf);
2055 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2056 return ret;
2057 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2058 lock_page(page);
2059 if (!page->mapping) {
2060 unlock_page(page);
2061 return 0; /* retry */
2062 }
2063 ret |= VM_FAULT_LOCKED;
2064 } else
2065 VM_BUG_ON_PAGE(!PageLocked(page), page);
2066 return ret;
2067 }
2068
2069 /*
2070 * Handle write page faults for pages that can be reused in the current vma
2071 *
2072 * This can happen either due to the mapping being with the VM_SHARED flag,
2073 * or due to us being the last reference standing to the page. In either
2074 * case, all we need to do here is to mark the page as writable and update
2075 * any related book-keeping.
2076 */
2077 static inline int wp_page_reuse(struct fault_env *fe, pte_t orig_pte,
2078 struct page *page, int page_mkwrite, int dirty_shared)
2079 __releases(fe->ptl)
2080 {
2081 struct vm_area_struct *vma = fe->vma;
2082 pte_t entry;
2083 /*
2084 * Clear the pages cpupid information as the existing
2085 * information potentially belongs to a now completely
2086 * unrelated process.
2087 */
2088 if (page)
2089 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2090
2091 flush_cache_page(vma, fe->address, pte_pfn(orig_pte));
2092 entry = pte_mkyoung(orig_pte);
2093 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2094 if (ptep_set_access_flags(vma, fe->address, fe->pte, entry, 1))
2095 update_mmu_cache(vma, fe->address, fe->pte);
2096 pte_unmap_unlock(fe->pte, fe->ptl);
2097
2098 if (dirty_shared) {
2099 struct address_space *mapping;
2100 int dirtied;
2101
2102 if (!page_mkwrite)
2103 lock_page(page);
2104
2105 dirtied = set_page_dirty(page);
2106 VM_BUG_ON_PAGE(PageAnon(page), page);
2107 mapping = page->mapping;
2108 unlock_page(page);
2109 put_page(page);
2110
2111 if ((dirtied || page_mkwrite) && mapping) {
2112 /*
2113 * Some device drivers do not set page.mapping
2114 * but still dirty their pages
2115 */
2116 balance_dirty_pages_ratelimited(mapping);
2117 }
2118
2119 if (!page_mkwrite)
2120 file_update_time(vma->vm_file);
2121 }
2122
2123 return VM_FAULT_WRITE;
2124 }
2125
2126 /*
2127 * Handle the case of a page which we actually need to copy to a new page.
2128 *
2129 * Called with mmap_sem locked and the old page referenced, but
2130 * without the ptl held.
2131 *
2132 * High level logic flow:
2133 *
2134 * - Allocate a page, copy the content of the old page to the new one.
2135 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2136 * - Take the PTL. If the pte changed, bail out and release the allocated page
2137 * - If the pte is still the way we remember it, update the page table and all
2138 * relevant references. This includes dropping the reference the page-table
2139 * held to the old page, as well as updating the rmap.
2140 * - In any case, unlock the PTL and drop the reference we took to the old page.
2141 */
2142 static int wp_page_copy(struct fault_env *fe, pte_t orig_pte,
2143 struct page *old_page)
2144 {
2145 struct vm_area_struct *vma = fe->vma;
2146 struct mm_struct *mm = vma->vm_mm;
2147 struct page *new_page = NULL;
2148 pte_t entry;
2149 int page_copied = 0;
2150 const unsigned long mmun_start = fe->address & PAGE_MASK;
2151 const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2152 struct mem_cgroup *memcg;
2153
2154 if (unlikely(anon_vma_prepare(vma)))
2155 goto oom;
2156
2157 if (is_zero_pfn(pte_pfn(orig_pte))) {
2158 new_page = alloc_zeroed_user_highpage_movable(vma, fe->address);
2159 if (!new_page)
2160 goto oom;
2161 } else {
2162 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2163 fe->address);
2164 if (!new_page)
2165 goto oom;
2166 cow_user_page(new_page, old_page, fe->address, vma);
2167 }
2168
2169 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2170 goto oom_free_new;
2171
2172 __SetPageUptodate(new_page);
2173
2174 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2175
2176 /*
2177 * Re-check the pte - we dropped the lock
2178 */
2179 fe->pte = pte_offset_map_lock(mm, fe->pmd, fe->address, &fe->ptl);
2180 if (likely(pte_same(*fe->pte, orig_pte))) {
2181 if (old_page) {
2182 if (!PageAnon(old_page)) {
2183 dec_mm_counter_fast(mm,
2184 mm_counter_file(old_page));
2185 inc_mm_counter_fast(mm, MM_ANONPAGES);
2186 }
2187 } else {
2188 inc_mm_counter_fast(mm, MM_ANONPAGES);
2189 }
2190 flush_cache_page(vma, fe->address, pte_pfn(orig_pte));
2191 entry = mk_pte(new_page, vma->vm_page_prot);
2192 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2193 /*
2194 * Clear the pte entry and flush it first, before updating the
2195 * pte with the new entry. This will avoid a race condition
2196 * seen in the presence of one thread doing SMC and another
2197 * thread doing COW.
2198 */
2199 ptep_clear_flush_notify(vma, fe->address, fe->pte);
2200 page_add_new_anon_rmap(new_page, vma, fe->address, false);
2201 mem_cgroup_commit_charge(new_page, memcg, false, false);
2202 lru_cache_add_active_or_unevictable(new_page, vma);
2203 /*
2204 * We call the notify macro here because, when using secondary
2205 * mmu page tables (such as kvm shadow page tables), we want the
2206 * new page to be mapped directly into the secondary page table.
2207 */
2208 set_pte_at_notify(mm, fe->address, fe->pte, entry);
2209 update_mmu_cache(vma, fe->address, fe->pte);
2210 if (old_page) {
2211 /*
2212 * Only after switching the pte to the new page may
2213 * we remove the mapcount here. Otherwise another
2214 * process may come and find the rmap count decremented
2215 * before the pte is switched to the new page, and
2216 * "reuse" the old page writing into it while our pte
2217 * here still points into it and can be read by other
2218 * threads.
2219 *
2220 * The critical issue is to order this
2221 * page_remove_rmap with the ptp_clear_flush above.
2222 * Those stores are ordered by (if nothing else,)
2223 * the barrier present in the atomic_add_negative
2224 * in page_remove_rmap.
2225 *
2226 * Then the TLB flush in ptep_clear_flush ensures that
2227 * no process can access the old page before the
2228 * decremented mapcount is visible. And the old page
2229 * cannot be reused until after the decremented
2230 * mapcount is visible. So transitively, TLBs to
2231 * old page will be flushed before it can be reused.
2232 */
2233 page_remove_rmap(old_page, false);
2234 }
2235
2236 /* Free the old page.. */
2237 new_page = old_page;
2238 page_copied = 1;
2239 } else {
2240 mem_cgroup_cancel_charge(new_page, memcg, false);
2241 }
2242
2243 if (new_page)
2244 put_page(new_page);
2245
2246 pte_unmap_unlock(fe->pte, fe->ptl);
2247 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2248 if (old_page) {
2249 /*
2250 * Don't let another task, with possibly unlocked vma,
2251 * keep the mlocked page.
2252 */
2253 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2254 lock_page(old_page); /* LRU manipulation */
2255 if (PageMlocked(old_page))
2256 munlock_vma_page(old_page);
2257 unlock_page(old_page);
2258 }
2259 put_page(old_page);
2260 }
2261 return page_copied ? VM_FAULT_WRITE : 0;
2262 oom_free_new:
2263 put_page(new_page);
2264 oom:
2265 if (old_page)
2266 put_page(old_page);
2267 return VM_FAULT_OOM;
2268 }
2269
2270 /*
2271 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2272 * mapping
2273 */
2274 static int wp_pfn_shared(struct fault_env *fe, pte_t orig_pte)
2275 {
2276 struct vm_area_struct *vma = fe->vma;
2277
2278 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2279 struct vm_fault vmf = {
2280 .page = NULL,
2281 .pgoff = linear_page_index(vma, fe->address),
2282 .virtual_address =
2283 (void __user *)(fe->address & PAGE_MASK),
2284 .flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
2285 };
2286 int ret;
2287
2288 pte_unmap_unlock(fe->pte, fe->ptl);
2289 ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
2290 if (ret & VM_FAULT_ERROR)
2291 return ret;
2292 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
2293 &fe->ptl);
2294 /*
2295 * We might have raced with another page fault while we
2296 * released the pte_offset_map_lock.
2297 */
2298 if (!pte_same(*fe->pte, orig_pte)) {
2299 pte_unmap_unlock(fe->pte, fe->ptl);
2300 return 0;
2301 }
2302 }
2303 return wp_page_reuse(fe, orig_pte, NULL, 0, 0);
2304 }
2305
2306 static int wp_page_shared(struct fault_env *fe, pte_t orig_pte,
2307 struct page *old_page)
2308 __releases(fe->ptl)
2309 {
2310 struct vm_area_struct *vma = fe->vma;
2311 int page_mkwrite = 0;
2312
2313 get_page(old_page);
2314
2315 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2316 int tmp;
2317
2318 pte_unmap_unlock(fe->pte, fe->ptl);
2319 tmp = do_page_mkwrite(vma, old_page, fe->address);
2320 if (unlikely(!tmp || (tmp &
2321 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2322 put_page(old_page);
2323 return tmp;
2324 }
2325 /*
2326 * Since we dropped the lock we need to revalidate
2327 * the PTE as someone else may have changed it. If
2328 * they did, we just return, as we can count on the
2329 * MMU to tell us if they didn't also make it writable.
2330 */
2331 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
2332 &fe->ptl);
2333 if (!pte_same(*fe->pte, orig_pte)) {
2334 unlock_page(old_page);
2335 pte_unmap_unlock(fe->pte, fe->ptl);
2336 put_page(old_page);
2337 return 0;
2338 }
2339 page_mkwrite = 1;
2340 }
2341
2342 return wp_page_reuse(fe, orig_pte, old_page, page_mkwrite, 1);
2343 }
2344
2345 /*
2346 * This routine handles present pages, when users try to write
2347 * to a shared page. It is done by copying the page to a new address
2348 * and decrementing the shared-page counter for the old page.
2349 *
2350 * Note that this routine assumes that the protection checks have been
2351 * done by the caller (the low-level page fault routine in most cases).
2352 * Thus we can safely just mark it writable once we've done any necessary
2353 * COW.
2354 *
2355 * We also mark the page dirty at this point even though the page will
2356 * change only once the write actually happens. This avoids a few races,
2357 * and potentially makes it more efficient.
2358 *
2359 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2360 * but allow concurrent faults), with pte both mapped and locked.
2361 * We return with mmap_sem still held, but pte unmapped and unlocked.
2362 */
2363 static int do_wp_page(struct fault_env *fe, pte_t orig_pte)
2364 __releases(fe->ptl)
2365 {
2366 struct vm_area_struct *vma = fe->vma;
2367 struct page *old_page;
2368
2369 old_page = vm_normal_page(vma, fe->address, orig_pte);
2370 if (!old_page) {
2371 /*
2372 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2373 * VM_PFNMAP VMA.
2374 *
2375 * We should not cow pages in a shared writeable mapping.
2376 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2377 */
2378 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2379 (VM_WRITE|VM_SHARED))
2380 return wp_pfn_shared(fe, orig_pte);
2381
2382 pte_unmap_unlock(fe->pte, fe->ptl);
2383 return wp_page_copy(fe, orig_pte, old_page);
2384 }
2385
2386 /*
2387 * Take out anonymous pages first, anonymous shared vmas are
2388 * not dirty accountable.
2389 */
2390 if (PageAnon(old_page) && !PageKsm(old_page)) {
2391 int total_mapcount;
2392 if (!trylock_page(old_page)) {
2393 get_page(old_page);
2394 pte_unmap_unlock(fe->pte, fe->ptl);
2395 lock_page(old_page);
2396 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd,
2397 fe->address, &fe->ptl);
2398 if (!pte_same(*fe->pte, orig_pte)) {
2399 unlock_page(old_page);
2400 pte_unmap_unlock(fe->pte, fe->ptl);
2401 put_page(old_page);
2402 return 0;
2403 }
2404 put_page(old_page);
2405 }
2406 if (reuse_swap_page(old_page, &total_mapcount)) {
2407 if (total_mapcount == 1) {
2408 /*
2409 * The page is all ours. Move it to
2410 * our anon_vma so the rmap code will
2411 * not search our parent or siblings.
2412 * Protected against the rmap code by
2413 * the page lock.
2414 */
2415 page_move_anon_rmap(old_page, vma);
2416 }
2417 unlock_page(old_page);
2418 return wp_page_reuse(fe, orig_pte, old_page, 0, 0);
2419 }
2420 unlock_page(old_page);
2421 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2422 (VM_WRITE|VM_SHARED))) {
2423 return wp_page_shared(fe, orig_pte, old_page);
2424 }
2425
2426 /*
2427 * Ok, we need to copy. Oh, well..
2428 */
2429 get_page(old_page);
2430
2431 pte_unmap_unlock(fe->pte, fe->ptl);
2432 return wp_page_copy(fe, orig_pte, old_page);
2433 }
2434
2435 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2436 unsigned long start_addr, unsigned long end_addr,
2437 struct zap_details *details)
2438 {
2439 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2440 }
2441
2442 static inline void unmap_mapping_range_tree(struct rb_root *root,
2443 struct zap_details *details)
2444 {
2445 struct vm_area_struct *vma;
2446 pgoff_t vba, vea, zba, zea;
2447
2448 vma_interval_tree_foreach(vma, root,
2449 details->first_index, details->last_index) {
2450
2451 vba = vma->vm_pgoff;
2452 vea = vba + vma_pages(vma) - 1;
2453 zba = details->first_index;
2454 if (zba < vba)
2455 zba = vba;
2456 zea = details->last_index;
2457 if (zea > vea)
2458 zea = vea;
2459
2460 unmap_mapping_range_vma(vma,
2461 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2462 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2463 details);
2464 }
2465 }
2466
2467 /**
2468 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2469 * address_space corresponding to the specified page range in the underlying
2470 * file.
2471 *
2472 * @mapping: the address space containing mmaps to be unmapped.
2473 * @holebegin: byte in first page to unmap, relative to the start of
2474 * the underlying file. This will be rounded down to a PAGE_SIZE
2475 * boundary. Note that this is different from truncate_pagecache(), which
2476 * must keep the partial page. In contrast, we must get rid of
2477 * partial pages.
2478 * @holelen: size of prospective hole in bytes. This will be rounded
2479 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2480 * end of the file.
2481 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2482 * but 0 when invalidating pagecache, don't throw away private data.
2483 */
2484 void unmap_mapping_range(struct address_space *mapping,
2485 loff_t const holebegin, loff_t const holelen, int even_cows)
2486 {
2487 struct zap_details details = { };
2488 pgoff_t hba = holebegin >> PAGE_SHIFT;
2489 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2490
2491 /* Check for overflow. */
2492 if (sizeof(holelen) > sizeof(hlen)) {
2493 long long holeend =
2494 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2495 if (holeend & ~(long long)ULONG_MAX)
2496 hlen = ULONG_MAX - hba + 1;
2497 }
2498
2499 details.check_mapping = even_cows? NULL: mapping;
2500 details.first_index = hba;
2501 details.last_index = hba + hlen - 1;
2502 if (details.last_index < details.first_index)
2503 details.last_index = ULONG_MAX;
2504
2505 i_mmap_lock_write(mapping);
2506 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2507 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2508 i_mmap_unlock_write(mapping);
2509 }
2510 EXPORT_SYMBOL(unmap_mapping_range);
2511
2512 /*
2513 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2514 * but allow concurrent faults), and pte mapped but not yet locked.
2515 * We return with pte unmapped and unlocked.
2516 *
2517 * We return with the mmap_sem locked or unlocked in the same cases
2518 * as does filemap_fault().
2519 */
2520 int do_swap_page(struct fault_env *fe, pte_t orig_pte)
2521 {
2522 struct vm_area_struct *vma = fe->vma;
2523 struct page *page, *swapcache;
2524 struct mem_cgroup *memcg;
2525 swp_entry_t entry;
2526 pte_t pte;
2527 int locked;
2528 int exclusive = 0;
2529 int ret = 0;
2530
2531 if (!pte_unmap_same(vma->vm_mm, fe->pmd, fe->pte, orig_pte))
2532 goto out;
2533
2534 entry = pte_to_swp_entry(orig_pte);
2535 if (unlikely(non_swap_entry(entry))) {
2536 if (is_migration_entry(entry)) {
2537 migration_entry_wait(vma->vm_mm, fe->pmd, fe->address);
2538 } else if (is_hwpoison_entry(entry)) {
2539 ret = VM_FAULT_HWPOISON;
2540 } else {
2541 print_bad_pte(vma, fe->address, orig_pte, NULL);
2542 ret = VM_FAULT_SIGBUS;
2543 }
2544 goto out;
2545 }
2546 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2547 page = lookup_swap_cache(entry);
2548 if (!page) {
2549 page = swapin_readahead(entry,
2550 GFP_HIGHUSER_MOVABLE, vma, fe->address);
2551 if (!page) {
2552 /*
2553 * Back out if somebody else faulted in this pte
2554 * while we released the pte lock.
2555 */
2556 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd,
2557 fe->address, &fe->ptl);
2558 if (likely(pte_same(*fe->pte, orig_pte)))
2559 ret = VM_FAULT_OOM;
2560 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2561 goto unlock;
2562 }
2563
2564 /* Had to read the page from swap area: Major fault */
2565 ret = VM_FAULT_MAJOR;
2566 count_vm_event(PGMAJFAULT);
2567 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
2568 } else if (PageHWPoison(page)) {
2569 /*
2570 * hwpoisoned dirty swapcache pages are kept for killing
2571 * owner processes (which may be unknown at hwpoison time)
2572 */
2573 ret = VM_FAULT_HWPOISON;
2574 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2575 swapcache = page;
2576 goto out_release;
2577 }
2578
2579 swapcache = page;
2580 locked = lock_page_or_retry(page, vma->vm_mm, fe->flags);
2581
2582 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2583 if (!locked) {
2584 ret |= VM_FAULT_RETRY;
2585 goto out_release;
2586 }
2587
2588 /*
2589 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2590 * release the swapcache from under us. The page pin, and pte_same
2591 * test below, are not enough to exclude that. Even if it is still
2592 * swapcache, we need to check that the page's swap has not changed.
2593 */
2594 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2595 goto out_page;
2596
2597 page = ksm_might_need_to_copy(page, vma, fe->address);
2598 if (unlikely(!page)) {
2599 ret = VM_FAULT_OOM;
2600 page = swapcache;
2601 goto out_page;
2602 }
2603
2604 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2605 &memcg, false)) {
2606 ret = VM_FAULT_OOM;
2607 goto out_page;
2608 }
2609
2610 /*
2611 * Back out if somebody else already faulted in this pte.
2612 */
2613 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
2614 &fe->ptl);
2615 if (unlikely(!pte_same(*fe->pte, orig_pte)))
2616 goto out_nomap;
2617
2618 if (unlikely(!PageUptodate(page))) {
2619 ret = VM_FAULT_SIGBUS;
2620 goto out_nomap;
2621 }
2622
2623 /*
2624 * The page isn't present yet, go ahead with the fault.
2625 *
2626 * Be careful about the sequence of operations here.
2627 * To get its accounting right, reuse_swap_page() must be called
2628 * while the page is counted on swap but not yet in mapcount i.e.
2629 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2630 * must be called after the swap_free(), or it will never succeed.
2631 */
2632
2633 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2634 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2635 pte = mk_pte(page, vma->vm_page_prot);
2636 if ((fe->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2637 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2638 fe->flags &= ~FAULT_FLAG_WRITE;
2639 ret |= VM_FAULT_WRITE;
2640 exclusive = RMAP_EXCLUSIVE;
2641 }
2642 flush_icache_page(vma, page);
2643 if (pte_swp_soft_dirty(orig_pte))
2644 pte = pte_mksoft_dirty(pte);
2645 set_pte_at(vma->vm_mm, fe->address, fe->pte, pte);
2646 if (page == swapcache) {
2647 do_page_add_anon_rmap(page, vma, fe->address, exclusive);
2648 mem_cgroup_commit_charge(page, memcg, true, false);
2649 activate_page(page);
2650 } else { /* ksm created a completely new copy */
2651 page_add_new_anon_rmap(page, vma, fe->address, false);
2652 mem_cgroup_commit_charge(page, memcg, false, false);
2653 lru_cache_add_active_or_unevictable(page, vma);
2654 }
2655
2656 swap_free(entry);
2657 if (mem_cgroup_swap_full(page) ||
2658 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2659 try_to_free_swap(page);
2660 unlock_page(page);
2661 if (page != swapcache) {
2662 /*
2663 * Hold the lock to avoid the swap entry to be reused
2664 * until we take the PT lock for the pte_same() check
2665 * (to avoid false positives from pte_same). For
2666 * further safety release the lock after the swap_free
2667 * so that the swap count won't change under a
2668 * parallel locked swapcache.
2669 */
2670 unlock_page(swapcache);
2671 put_page(swapcache);
2672 }
2673
2674 if (fe->flags & FAULT_FLAG_WRITE) {
2675 ret |= do_wp_page(fe, pte);
2676 if (ret & VM_FAULT_ERROR)
2677 ret &= VM_FAULT_ERROR;
2678 goto out;
2679 }
2680
2681 /* No need to invalidate - it was non-present before */
2682 update_mmu_cache(vma, fe->address, fe->pte);
2683 unlock:
2684 pte_unmap_unlock(fe->pte, fe->ptl);
2685 out:
2686 return ret;
2687 out_nomap:
2688 mem_cgroup_cancel_charge(page, memcg, false);
2689 pte_unmap_unlock(fe->pte, fe->ptl);
2690 out_page:
2691 unlock_page(page);
2692 out_release:
2693 put_page(page);
2694 if (page != swapcache) {
2695 unlock_page(swapcache);
2696 put_page(swapcache);
2697 }
2698 return ret;
2699 }
2700
2701 /*
2702 * This is like a special single-page "expand_{down|up}wards()",
2703 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2704 * doesn't hit another vma.
2705 */
2706 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2707 {
2708 address &= PAGE_MASK;
2709 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2710 struct vm_area_struct *prev = vma->vm_prev;
2711
2712 /*
2713 * Is there a mapping abutting this one below?
2714 *
2715 * That's only ok if it's the same stack mapping
2716 * that has gotten split..
2717 */
2718 if (prev && prev->vm_end == address)
2719 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2720
2721 return expand_downwards(vma, address - PAGE_SIZE);
2722 }
2723 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2724 struct vm_area_struct *next = vma->vm_next;
2725
2726 /* As VM_GROWSDOWN but s/below/above/ */
2727 if (next && next->vm_start == address + PAGE_SIZE)
2728 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2729
2730 return expand_upwards(vma, address + PAGE_SIZE);
2731 }
2732 return 0;
2733 }
2734
2735 /*
2736 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2737 * but allow concurrent faults), and pte mapped but not yet locked.
2738 * We return with mmap_sem still held, but pte unmapped and unlocked.
2739 */
2740 static int do_anonymous_page(struct fault_env *fe)
2741 {
2742 struct vm_area_struct *vma = fe->vma;
2743 struct mem_cgroup *memcg;
2744 struct page *page;
2745 pte_t entry;
2746
2747 /* File mapping without ->vm_ops ? */
2748 if (vma->vm_flags & VM_SHARED)
2749 return VM_FAULT_SIGBUS;
2750
2751 /* Check if we need to add a guard page to the stack */
2752 if (check_stack_guard_page(vma, fe->address) < 0)
2753 return VM_FAULT_SIGSEGV;
2754
2755 /*
2756 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2757 * pte_offset_map() on pmds where a huge pmd might be created
2758 * from a different thread.
2759 *
2760 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2761 * parallel threads are excluded by other means.
2762 *
2763 * Here we only have down_read(mmap_sem).
2764 */
2765 if (pte_alloc(vma->vm_mm, fe->pmd, fe->address))
2766 return VM_FAULT_OOM;
2767
2768 /* See the comment in pte_alloc_one_map() */
2769 if (unlikely(pmd_trans_unstable(fe->pmd)))
2770 return 0;
2771
2772 /* Use the zero-page for reads */
2773 if (!(fe->flags & FAULT_FLAG_WRITE) &&
2774 !mm_forbids_zeropage(vma->vm_mm)) {
2775 entry = pte_mkspecial(pfn_pte(my_zero_pfn(fe->address),
2776 vma->vm_page_prot));
2777 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
2778 &fe->ptl);
2779 if (!pte_none(*fe->pte))
2780 goto unlock;
2781 /* Deliver the page fault to userland, check inside PT lock */
2782 if (userfaultfd_missing(vma)) {
2783 pte_unmap_unlock(fe->pte, fe->ptl);
2784 return handle_userfault(fe, VM_UFFD_MISSING);
2785 }
2786 goto setpte;
2787 }
2788
2789 /* Allocate our own private page. */
2790 if (unlikely(anon_vma_prepare(vma)))
2791 goto oom;
2792 page = alloc_zeroed_user_highpage_movable(vma, fe->address);
2793 if (!page)
2794 goto oom;
2795
2796 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
2797 goto oom_free_page;
2798
2799 /*
2800 * The memory barrier inside __SetPageUptodate makes sure that
2801 * preceeding stores to the page contents become visible before
2802 * the set_pte_at() write.
2803 */
2804 __SetPageUptodate(page);
2805
2806 entry = mk_pte(page, vma->vm_page_prot);
2807 if (vma->vm_flags & VM_WRITE)
2808 entry = pte_mkwrite(pte_mkdirty(entry));
2809
2810 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
2811 &fe->ptl);
2812 if (!pte_none(*fe->pte))
2813 goto release;
2814
2815 /* Deliver the page fault to userland, check inside PT lock */
2816 if (userfaultfd_missing(vma)) {
2817 pte_unmap_unlock(fe->pte, fe->ptl);
2818 mem_cgroup_cancel_charge(page, memcg, false);
2819 put_page(page);
2820 return handle_userfault(fe, VM_UFFD_MISSING);
2821 }
2822
2823 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2824 page_add_new_anon_rmap(page, vma, fe->address, false);
2825 mem_cgroup_commit_charge(page, memcg, false, false);
2826 lru_cache_add_active_or_unevictable(page, vma);
2827 setpte:
2828 set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
2829
2830 /* No need to invalidate - it was non-present before */
2831 update_mmu_cache(vma, fe->address, fe->pte);
2832 unlock:
2833 pte_unmap_unlock(fe->pte, fe->ptl);
2834 return 0;
2835 release:
2836 mem_cgroup_cancel_charge(page, memcg, false);
2837 put_page(page);
2838 goto unlock;
2839 oom_free_page:
2840 put_page(page);
2841 oom:
2842 return VM_FAULT_OOM;
2843 }
2844
2845 /*
2846 * The mmap_sem must have been held on entry, and may have been
2847 * released depending on flags and vma->vm_ops->fault() return value.
2848 * See filemap_fault() and __lock_page_retry().
2849 */
2850 static int __do_fault(struct fault_env *fe, pgoff_t pgoff,
2851 struct page *cow_page, struct page **page, void **entry)
2852 {
2853 struct vm_area_struct *vma = fe->vma;
2854 struct vm_fault vmf;
2855 int ret;
2856
2857 vmf.virtual_address = (void __user *)(fe->address & PAGE_MASK);
2858 vmf.pgoff = pgoff;
2859 vmf.flags = fe->flags;
2860 vmf.page = NULL;
2861 vmf.gfp_mask = __get_fault_gfp_mask(vma);
2862 vmf.cow_page = cow_page;
2863
2864 ret = vma->vm_ops->fault(vma, &vmf);
2865 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2866 return ret;
2867 if (ret & VM_FAULT_DAX_LOCKED) {
2868 *entry = vmf.entry;
2869 return ret;
2870 }
2871
2872 if (unlikely(PageHWPoison(vmf.page))) {
2873 if (ret & VM_FAULT_LOCKED)
2874 unlock_page(vmf.page);
2875 put_page(vmf.page);
2876 return VM_FAULT_HWPOISON;
2877 }
2878
2879 if (unlikely(!(ret & VM_FAULT_LOCKED)))
2880 lock_page(vmf.page);
2881 else
2882 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
2883
2884 *page = vmf.page;
2885 return ret;
2886 }
2887
2888 static int pte_alloc_one_map(struct fault_env *fe)
2889 {
2890 struct vm_area_struct *vma = fe->vma;
2891
2892 if (!pmd_none(*fe->pmd))
2893 goto map_pte;
2894 if (fe->prealloc_pte) {
2895 fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
2896 if (unlikely(!pmd_none(*fe->pmd))) {
2897 spin_unlock(fe->ptl);
2898 goto map_pte;
2899 }
2900
2901 atomic_long_inc(&vma->vm_mm->nr_ptes);
2902 pmd_populate(vma->vm_mm, fe->pmd, fe->prealloc_pte);
2903 spin_unlock(fe->ptl);
2904 fe->prealloc_pte = 0;
2905 } else if (unlikely(pte_alloc(vma->vm_mm, fe->pmd, fe->address))) {
2906 return VM_FAULT_OOM;
2907 }
2908 map_pte:
2909 /*
2910 * If a huge pmd materialized under us just retry later. Use
2911 * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
2912 * didn't become pmd_trans_huge under us and then back to pmd_none, as
2913 * a result of MADV_DONTNEED running immediately after a huge pmd fault
2914 * in a different thread of this mm, in turn leading to a misleading
2915 * pmd_trans_huge() retval. All we have to ensure is that it is a
2916 * regular pmd that we can walk with pte_offset_map() and we can do that
2917 * through an atomic read in C, which is what pmd_trans_unstable()
2918 * provides.
2919 */
2920 if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))
2921 return VM_FAULT_NOPAGE;
2922
2923 fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
2924 &fe->ptl);
2925 return 0;
2926 }
2927
2928 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
2929
2930 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
2931 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
2932 unsigned long haddr)
2933 {
2934 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
2935 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
2936 return false;
2937 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
2938 return false;
2939 return true;
2940 }
2941
2942 static int do_set_pmd(struct fault_env *fe, struct page *page)
2943 {
2944 struct vm_area_struct *vma = fe->vma;
2945 bool write = fe->flags & FAULT_FLAG_WRITE;
2946 unsigned long haddr = fe->address & HPAGE_PMD_MASK;
2947 pmd_t entry;
2948 int i, ret;
2949
2950 if (!transhuge_vma_suitable(vma, haddr))
2951 return VM_FAULT_FALLBACK;
2952
2953 ret = VM_FAULT_FALLBACK;
2954 page = compound_head(page);
2955
2956 fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
2957 if (unlikely(!pmd_none(*fe->pmd)))
2958 goto out;
2959
2960 for (i = 0; i < HPAGE_PMD_NR; i++)
2961 flush_icache_page(vma, page + i);
2962
2963 entry = mk_huge_pmd(page, vma->vm_page_prot);
2964 if (write)
2965 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
2966
2967 add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
2968 page_add_file_rmap(page, true);
2969
2970 set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
2971
2972 update_mmu_cache_pmd(vma, haddr, fe->pmd);
2973
2974 /* fault is handled */
2975 ret = 0;
2976 count_vm_event(THP_FILE_MAPPED);
2977 out:
2978 spin_unlock(fe->ptl);
2979 return ret;
2980 }
2981 #else
2982 static int do_set_pmd(struct fault_env *fe, struct page *page)
2983 {
2984 BUILD_BUG();
2985 return 0;
2986 }
2987 #endif
2988
2989 /**
2990 * alloc_set_pte - setup new PTE entry for given page and add reverse page
2991 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
2992 *
2993 * @fe: fault environment
2994 * @memcg: memcg to charge page (only for private mappings)
2995 * @page: page to map
2996 *
2997 * Caller must take care of unlocking fe->ptl, if fe->pte is non-NULL on return.
2998 *
2999 * Target users are page handler itself and implementations of
3000 * vm_ops->map_pages.
3001 */
3002 int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
3003 struct page *page)
3004 {
3005 struct vm_area_struct *vma = fe->vma;
3006 bool write = fe->flags & FAULT_FLAG_WRITE;
3007 pte_t entry;
3008 int ret;
3009
3010 if (pmd_none(*fe->pmd) && PageTransCompound(page) &&
3011 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3012 /* THP on COW? */
3013 VM_BUG_ON_PAGE(memcg, page);
3014
3015 ret = do_set_pmd(fe, page);
3016 if (ret != VM_FAULT_FALLBACK)
3017 return ret;
3018 }
3019
3020 if (!fe->pte) {
3021 ret = pte_alloc_one_map(fe);
3022 if (ret)
3023 return ret;
3024 }
3025
3026 /* Re-check under ptl */
3027 if (unlikely(!pte_none(*fe->pte)))
3028 return VM_FAULT_NOPAGE;
3029
3030 flush_icache_page(vma, page);
3031 entry = mk_pte(page, vma->vm_page_prot);
3032 if (write)
3033 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3034 /* copy-on-write page */
3035 if (write && !(vma->vm_flags & VM_SHARED)) {
3036 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3037 page_add_new_anon_rmap(page, vma, fe->address, false);
3038 mem_cgroup_commit_charge(page, memcg, false, false);
3039 lru_cache_add_active_or_unevictable(page, vma);
3040 } else {
3041 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3042 page_add_file_rmap(page, false);
3043 }
3044 set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
3045
3046 /* no need to invalidate: a not-present page won't be cached */
3047 update_mmu_cache(vma, fe->address, fe->pte);
3048
3049 return 0;
3050 }
3051
3052 static unsigned long fault_around_bytes __read_mostly =
3053 rounddown_pow_of_two(65536);
3054
3055 #ifdef CONFIG_DEBUG_FS
3056 static int fault_around_bytes_get(void *data, u64 *val)
3057 {
3058 *val = fault_around_bytes;
3059 return 0;
3060 }
3061
3062 /*
3063 * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3064 * rounded down to nearest page order. It's what do_fault_around() expects to
3065 * see.
3066 */
3067 static int fault_around_bytes_set(void *data, u64 val)
3068 {
3069 if (val / PAGE_SIZE > PTRS_PER_PTE)
3070 return -EINVAL;
3071 if (val > PAGE_SIZE)
3072 fault_around_bytes = rounddown_pow_of_two(val);
3073 else
3074 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3075 return 0;
3076 }
3077 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
3078 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3079
3080 static int __init fault_around_debugfs(void)
3081 {
3082 void *ret;
3083
3084 ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
3085 &fault_around_bytes_fops);
3086 if (!ret)
3087 pr_warn("Failed to create fault_around_bytes in debugfs");
3088 return 0;
3089 }
3090 late_initcall(fault_around_debugfs);
3091 #endif
3092
3093 /*
3094 * do_fault_around() tries to map few pages around the fault address. The hope
3095 * is that the pages will be needed soon and this will lower the number of
3096 * faults to handle.
3097 *
3098 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3099 * not ready to be mapped: not up-to-date, locked, etc.
3100 *
3101 * This function is called with the page table lock taken. In the split ptlock
3102 * case the page table lock only protects only those entries which belong to
3103 * the page table corresponding to the fault address.
3104 *
3105 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3106 * only once.
3107 *
3108 * fault_around_pages() defines how many pages we'll try to map.
3109 * do_fault_around() expects it to return a power of two less than or equal to
3110 * PTRS_PER_PTE.
3111 *
3112 * The virtual address of the area that we map is naturally aligned to the
3113 * fault_around_pages() value (and therefore to page order). This way it's
3114 * easier to guarantee that we don't cross page table boundaries.
3115 */
3116 static int do_fault_around(struct fault_env *fe, pgoff_t start_pgoff)
3117 {
3118 unsigned long address = fe->address, nr_pages, mask;
3119 pgoff_t end_pgoff;
3120 int off, ret = 0;
3121
3122 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3123 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3124
3125 fe->address = max(address & mask, fe->vma->vm_start);
3126 off = ((address - fe->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3127 start_pgoff -= off;
3128
3129 /*
3130 * end_pgoff is either end of page table or end of vma
3131 * or fault_around_pages() from start_pgoff, depending what is nearest.
3132 */
3133 end_pgoff = start_pgoff -
3134 ((fe->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3135 PTRS_PER_PTE - 1;
3136 end_pgoff = min3(end_pgoff, vma_pages(fe->vma) + fe->vma->vm_pgoff - 1,
3137 start_pgoff + nr_pages - 1);
3138
3139 if (pmd_none(*fe->pmd)) {
3140 fe->prealloc_pte = pte_alloc_one(fe->vma->vm_mm, fe->address);
3141 if (!fe->prealloc_pte)
3142 goto out;
3143 smp_wmb(); /* See comment in __pte_alloc() */
3144 }
3145
3146 fe->vma->vm_ops->map_pages(fe, start_pgoff, end_pgoff);
3147
3148 /* preallocated pagetable is unused: free it */
3149 if (fe->prealloc_pte) {
3150 pte_free(fe->vma->vm_mm, fe->prealloc_pte);
3151 fe->prealloc_pte = 0;
3152 }
3153 /* Huge page is mapped? Page fault is solved */
3154 if (pmd_trans_huge(*fe->pmd)) {
3155 ret = VM_FAULT_NOPAGE;
3156 goto out;
3157 }
3158
3159 /* ->map_pages() haven't done anything useful. Cold page cache? */
3160 if (!fe->pte)
3161 goto out;
3162
3163 /* check if the page fault is solved */
3164 fe->pte -= (fe->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3165 if (!pte_none(*fe->pte))
3166 ret = VM_FAULT_NOPAGE;
3167 pte_unmap_unlock(fe->pte, fe->ptl);
3168 out:
3169 fe->address = address;
3170 fe->pte = NULL;
3171 return ret;
3172 }
3173
3174 static int do_read_fault(struct fault_env *fe, pgoff_t pgoff)
3175 {
3176 struct vm_area_struct *vma = fe->vma;
3177 struct page *fault_page;
3178 int ret = 0;
3179
3180 /*
3181 * Let's call ->map_pages() first and use ->fault() as fallback
3182 * if page by the offset is not ready to be mapped (cold cache or
3183 * something).
3184 */
3185 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3186 ret = do_fault_around(fe, pgoff);
3187 if (ret)
3188 return ret;
3189 }
3190
3191 ret = __do_fault(fe, pgoff, NULL, &fault_page, NULL);
3192 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3193 return ret;
3194
3195 ret |= alloc_set_pte(fe, NULL, fault_page);
3196 if (fe->pte)
3197 pte_unmap_unlock(fe->pte, fe->ptl);
3198 unlock_page(fault_page);
3199 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3200 put_page(fault_page);
3201 return ret;
3202 }
3203
3204 static int do_cow_fault(struct fault_env *fe, pgoff_t pgoff)
3205 {
3206 struct vm_area_struct *vma = fe->vma;
3207 struct page *fault_page, *new_page;
3208 void *fault_entry;
3209 struct mem_cgroup *memcg;
3210 int ret;
3211
3212 if (unlikely(anon_vma_prepare(vma)))
3213 return VM_FAULT_OOM;
3214
3215 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, fe->address);
3216 if (!new_page)
3217 return VM_FAULT_OOM;
3218
3219 if (mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
3220 &memcg, false)) {
3221 put_page(new_page);
3222 return VM_FAULT_OOM;
3223 }
3224
3225 ret = __do_fault(fe, pgoff, new_page, &fault_page, &fault_entry);
3226 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3227 goto uncharge_out;
3228
3229 if (!(ret & VM_FAULT_DAX_LOCKED))
3230 copy_user_highpage(new_page, fault_page, fe->address, vma);
3231 __SetPageUptodate(new_page);
3232
3233 ret |= alloc_set_pte(fe, memcg, new_page);
3234 if (fe->pte)
3235 pte_unmap_unlock(fe->pte, fe->ptl);
3236 if (!(ret & VM_FAULT_DAX_LOCKED)) {
3237 unlock_page(fault_page);
3238 put_page(fault_page);
3239 } else {
3240 dax_unlock_mapping_entry(vma->vm_file->f_mapping, pgoff);
3241 }
3242 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3243 goto uncharge_out;
3244 return ret;
3245 uncharge_out:
3246 mem_cgroup_cancel_charge(new_page, memcg, false);
3247 put_page(new_page);
3248 return ret;
3249 }
3250
3251 static int do_shared_fault(struct fault_env *fe, pgoff_t pgoff)
3252 {
3253 struct vm_area_struct *vma = fe->vma;
3254 struct page *fault_page;
3255 struct address_space *mapping;
3256 int dirtied = 0;
3257 int ret, tmp;
3258
3259 ret = __do_fault(fe, pgoff, NULL, &fault_page, NULL);
3260 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3261 return ret;
3262
3263 /*
3264 * Check if the backing address space wants to know that the page is
3265 * about to become writable
3266 */
3267 if (vma->vm_ops->page_mkwrite) {
3268 unlock_page(fault_page);
3269 tmp = do_page_mkwrite(vma, fault_page, fe->address);
3270 if (unlikely(!tmp ||
3271 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3272 put_page(fault_page);
3273 return tmp;
3274 }
3275 }
3276
3277 ret |= alloc_set_pte(fe, NULL, fault_page);
3278 if (fe->pte)
3279 pte_unmap_unlock(fe->pte, fe->ptl);
3280 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3281 VM_FAULT_RETRY))) {
3282 unlock_page(fault_page);
3283 put_page(fault_page);
3284 return ret;
3285 }
3286
3287 if (set_page_dirty(fault_page))
3288 dirtied = 1;
3289 /*
3290 * Take a local copy of the address_space - page.mapping may be zeroed
3291 * by truncate after unlock_page(). The address_space itself remains
3292 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
3293 * release semantics to prevent the compiler from undoing this copying.
3294 */
3295 mapping = page_rmapping(fault_page);
3296 unlock_page(fault_page);
3297 if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
3298 /*
3299 * Some device drivers do not set page.mapping but still
3300 * dirty their pages
3301 */
3302 balance_dirty_pages_ratelimited(mapping);
3303 }
3304
3305 if (!vma->vm_ops->page_mkwrite)
3306 file_update_time(vma->vm_file);
3307
3308 return ret;
3309 }
3310
3311 /*
3312 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3313 * but allow concurrent faults).
3314 * The mmap_sem may have been released depending on flags and our
3315 * return value. See filemap_fault() and __lock_page_or_retry().
3316 */
3317 static int do_fault(struct fault_env *fe)
3318 {
3319 struct vm_area_struct *vma = fe->vma;
3320 pgoff_t pgoff = linear_page_index(vma, fe->address);
3321
3322 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3323 if (!vma->vm_ops->fault)
3324 return VM_FAULT_SIGBUS;
3325 if (!(fe->flags & FAULT_FLAG_WRITE))
3326 return do_read_fault(fe, pgoff);
3327 if (!(vma->vm_flags & VM_SHARED))
3328 return do_cow_fault(fe, pgoff);
3329 return do_shared_fault(fe, pgoff);
3330 }
3331
3332 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3333 unsigned long addr, int page_nid,
3334 int *flags)
3335 {
3336 get_page(page);
3337
3338 count_vm_numa_event(NUMA_HINT_FAULTS);
3339 if (page_nid == numa_node_id()) {
3340 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3341 *flags |= TNF_FAULT_LOCAL;
3342 }
3343
3344 return mpol_misplaced(page, vma, addr);
3345 }
3346
3347 static int do_numa_page(struct fault_env *fe, pte_t pte)
3348 {
3349 struct vm_area_struct *vma = fe->vma;
3350 struct page *page = NULL;
3351 int page_nid = -1;
3352 int last_cpupid;
3353 int target_nid;
3354 bool migrated = false;
3355 bool was_writable = pte_write(pte);
3356 int flags = 0;
3357
3358 /*
3359 * The "pte" at this point cannot be used safely without
3360 * validation through pte_unmap_same(). It's of NUMA type but
3361 * the pfn may be screwed if the read is non atomic.
3362 *
3363 * We can safely just do a "set_pte_at()", because the old
3364 * page table entry is not accessible, so there would be no
3365 * concurrent hardware modifications to the PTE.
3366 */
3367 fe->ptl = pte_lockptr(vma->vm_mm, fe->pmd);
3368 spin_lock(fe->ptl);
3369 if (unlikely(!pte_same(*fe->pte, pte))) {
3370 pte_unmap_unlock(fe->pte, fe->ptl);
3371 goto out;
3372 }
3373
3374 /* Make it present again */
3375 pte = pte_modify(pte, vma->vm_page_prot);
3376 pte = pte_mkyoung(pte);
3377 if (was_writable)
3378 pte = pte_mkwrite(pte);
3379 set_pte_at(vma->vm_mm, fe->address, fe->pte, pte);
3380 update_mmu_cache(vma, fe->address, fe->pte);
3381
3382 page = vm_normal_page(vma, fe->address, pte);
3383 if (!page) {
3384 pte_unmap_unlock(fe->pte, fe->ptl);
3385 return 0;
3386 }
3387
3388 /* TODO: handle PTE-mapped THP */
3389 if (PageCompound(page)) {
3390 pte_unmap_unlock(fe->pte, fe->ptl);
3391 return 0;
3392 }
3393
3394 /*
3395 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3396 * much anyway since they can be in shared cache state. This misses
3397 * the case where a mapping is writable but the process never writes
3398 * to it but pte_write gets cleared during protection updates and
3399 * pte_dirty has unpredictable behaviour between PTE scan updates,
3400 * background writeback, dirty balancing and application behaviour.
3401 */
3402 if (!pte_write(pte))
3403 flags |= TNF_NO_GROUP;
3404
3405 /*
3406 * Flag if the page is shared between multiple address spaces. This
3407 * is later used when determining whether to group tasks together
3408 */
3409 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3410 flags |= TNF_SHARED;
3411
3412 last_cpupid = page_cpupid_last(page);
3413 page_nid = page_to_nid(page);
3414 target_nid = numa_migrate_prep(page, vma, fe->address, page_nid,
3415 &flags);
3416 pte_unmap_unlock(fe->pte, fe->ptl);
3417 if (target_nid == -1) {
3418 put_page(page);
3419 goto out;
3420 }
3421
3422 /* Migrate to the requested node */
3423 migrated = migrate_misplaced_page(page, vma, target_nid);
3424 if (migrated) {
3425 page_nid = target_nid;
3426 flags |= TNF_MIGRATED;
3427 } else
3428 flags |= TNF_MIGRATE_FAIL;
3429
3430 out:
3431 if (page_nid != -1)
3432 task_numa_fault(last_cpupid, page_nid, 1, flags);
3433 return 0;
3434 }
3435
3436 static int create_huge_pmd(struct fault_env *fe)
3437 {
3438 struct vm_area_struct *vma = fe->vma;
3439 if (vma_is_anonymous(vma))
3440 return do_huge_pmd_anonymous_page(fe);
3441 if (vma->vm_ops->pmd_fault)
3442 return vma->vm_ops->pmd_fault(vma, fe->address, fe->pmd,
3443 fe->flags);
3444 return VM_FAULT_FALLBACK;
3445 }
3446
3447 static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd)
3448 {
3449 if (vma_is_anonymous(fe->vma))
3450 return do_huge_pmd_wp_page(fe, orig_pmd);
3451 if (fe->vma->vm_ops->pmd_fault)
3452 return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd,
3453 fe->flags);
3454
3455 /* COW handled on pte level: split pmd */
3456 VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma);
3457 split_huge_pmd(fe->vma, fe->pmd, fe->address);
3458
3459 return VM_FAULT_FALLBACK;
3460 }
3461
3462 static inline bool vma_is_accessible(struct vm_area_struct *vma)
3463 {
3464 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3465 }
3466
3467 /*
3468 * These routines also need to handle stuff like marking pages dirty
3469 * and/or accessed for architectures that don't do it in hardware (most
3470 * RISC architectures). The early dirtying is also good on the i386.
3471 *
3472 * There is also a hook called "update_mmu_cache()" that architectures
3473 * with external mmu caches can use to update those (ie the Sparc or
3474 * PowerPC hashed page tables that act as extended TLBs).
3475 *
3476 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3477 * concurrent faults).
3478 *
3479 * The mmap_sem may have been released depending on flags and our return value.
3480 * See filemap_fault() and __lock_page_or_retry().
3481 */
3482 static int handle_pte_fault(struct fault_env *fe)
3483 {
3484 pte_t entry;
3485
3486 if (unlikely(pmd_none(*fe->pmd))) {
3487 /*
3488 * Leave __pte_alloc() until later: because vm_ops->fault may
3489 * want to allocate huge page, and if we expose page table
3490 * for an instant, it will be difficult to retract from
3491 * concurrent faults and from rmap lookups.
3492 */
3493 fe->pte = NULL;
3494 } else {
3495 /* See comment in pte_alloc_one_map() */
3496 if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))
3497 return 0;
3498 /*
3499 * A regular pmd is established and it can't morph into a huge
3500 * pmd from under us anymore at this point because we hold the
3501 * mmap_sem read mode and khugepaged takes it in write mode.
3502 * So now it's safe to run pte_offset_map().
3503 */
3504 fe->pte = pte_offset_map(fe->pmd, fe->address);
3505
3506 entry = *fe->pte;
3507
3508 /*
3509 * some architectures can have larger ptes than wordsize,
3510 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3511 * CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
3512 * atomic accesses. The code below just needs a consistent
3513 * view for the ifs and we later double check anyway with the
3514 * ptl lock held. So here a barrier will do.
3515 */
3516 barrier();
3517 if (pte_none(entry)) {
3518 pte_unmap(fe->pte);
3519 fe->pte = NULL;
3520 }
3521 }
3522
3523 if (!fe->pte) {
3524 if (vma_is_anonymous(fe->vma))
3525 return do_anonymous_page(fe);
3526 else
3527 return do_fault(fe);
3528 }
3529
3530 if (!pte_present(entry))
3531 return do_swap_page(fe, entry);
3532
3533 if (pte_protnone(entry) && vma_is_accessible(fe->vma))
3534 return do_numa_page(fe, entry);
3535
3536 fe->ptl = pte_lockptr(fe->vma->vm_mm, fe->pmd);
3537 spin_lock(fe->ptl);
3538 if (unlikely(!pte_same(*fe->pte, entry)))
3539 goto unlock;
3540 if (fe->flags & FAULT_FLAG_WRITE) {
3541 if (!pte_write(entry))
3542 return do_wp_page(fe, entry);
3543 entry = pte_mkdirty(entry);
3544 }
3545 entry = pte_mkyoung(entry);
3546 if (ptep_set_access_flags(fe->vma, fe->address, fe->pte, entry,
3547 fe->flags & FAULT_FLAG_WRITE)) {
3548 update_mmu_cache(fe->vma, fe->address, fe->pte);
3549 } else {
3550 /*
3551 * This is needed only for protection faults but the arch code
3552 * is not yet telling us if this is a protection fault or not.
3553 * This still avoids useless tlb flushes for .text page faults
3554 * with threads.
3555 */
3556 if (fe->flags & FAULT_FLAG_WRITE)
3557 flush_tlb_fix_spurious_fault(fe->vma, fe->address);
3558 }
3559 unlock:
3560 pte_unmap_unlock(fe->pte, fe->ptl);
3561 return 0;
3562 }
3563
3564 /*
3565 * By the time we get here, we already hold the mm semaphore
3566 *
3567 * The mmap_sem may have been released depending on flags and our
3568 * return value. See filemap_fault() and __lock_page_or_retry().
3569 */
3570 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3571 unsigned int flags)
3572 {
3573 struct fault_env fe = {
3574 .vma = vma,
3575 .address = address,
3576 .flags = flags,
3577 };
3578 struct mm_struct *mm = vma->vm_mm;
3579 pgd_t *pgd;
3580 pud_t *pud;
3581
3582 pgd = pgd_offset(mm, address);
3583 pud = pud_alloc(mm, pgd, address);
3584 if (!pud)
3585 return VM_FAULT_OOM;
3586 fe.pmd = pmd_alloc(mm, pud, address);
3587 if (!fe.pmd)
3588 return VM_FAULT_OOM;
3589 if (pmd_none(*fe.pmd) && transparent_hugepage_enabled(vma)) {
3590 int ret = create_huge_pmd(&fe);
3591 if (!(ret & VM_FAULT_FALLBACK))
3592 return ret;
3593 } else {
3594 pmd_t orig_pmd = *fe.pmd;
3595 int ret;
3596
3597 barrier();
3598 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3599 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
3600 return do_huge_pmd_numa_page(&fe, orig_pmd);
3601
3602 if ((fe.flags & FAULT_FLAG_WRITE) &&
3603 !pmd_write(orig_pmd)) {
3604 ret = wp_huge_pmd(&fe, orig_pmd);
3605 if (!(ret & VM_FAULT_FALLBACK))
3606 return ret;
3607 } else {
3608 huge_pmd_set_accessed(&fe, orig_pmd);
3609 return 0;
3610 }
3611 }
3612 }
3613
3614 return handle_pte_fault(&fe);
3615 }
3616
3617 /*
3618 * By the time we get here, we already hold the mm semaphore
3619 *
3620 * The mmap_sem may have been released depending on flags and our
3621 * return value. See filemap_fault() and __lock_page_or_retry().
3622 */
3623 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3624 unsigned int flags)
3625 {
3626 int ret;
3627
3628 __set_current_state(TASK_RUNNING);
3629
3630 count_vm_event(PGFAULT);
3631 mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
3632
3633 /* do counter updates before entering really critical section. */
3634 check_sync_rss_stat(current);
3635
3636 /*
3637 * Enable the memcg OOM handling for faults triggered in user
3638 * space. Kernel faults are handled more gracefully.
3639 */
3640 if (flags & FAULT_FLAG_USER)
3641 mem_cgroup_oom_enable();
3642
3643 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3644 flags & FAULT_FLAG_INSTRUCTION,
3645 flags & FAULT_FLAG_REMOTE))
3646 return VM_FAULT_SIGSEGV;
3647
3648 if (unlikely(is_vm_hugetlb_page(vma)))
3649 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
3650 else
3651 ret = __handle_mm_fault(vma, address, flags);
3652
3653 if (flags & FAULT_FLAG_USER) {
3654 mem_cgroup_oom_disable();
3655 /*
3656 * The task may have entered a memcg OOM situation but
3657 * if the allocation error was handled gracefully (no
3658 * VM_FAULT_OOM), there is no need to kill anything.
3659 * Just clean up the OOM state peacefully.
3660 */
3661 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3662 mem_cgroup_oom_synchronize(false);
3663 }
3664
3665 /*
3666 * This mm has been already reaped by the oom reaper and so the
3667 * refault cannot be trusted in general. Anonymous refaults would
3668 * lose data and give a zero page instead e.g. This is especially
3669 * problem for use_mm() because regular tasks will just die and
3670 * the corrupted data will not be visible anywhere while kthread
3671 * will outlive the oom victim and potentially propagate the date
3672 * further.
3673 */
3674 if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
3675 && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
3676 ret = VM_FAULT_SIGBUS;
3677
3678 return ret;
3679 }
3680 EXPORT_SYMBOL_GPL(handle_mm_fault);
3681
3682 #ifndef __PAGETABLE_PUD_FOLDED
3683 /*
3684 * Allocate page upper directory.
3685 * We've already handled the fast-path in-line.
3686 */
3687 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3688 {
3689 pud_t *new = pud_alloc_one(mm, address);
3690 if (!new)
3691 return -ENOMEM;
3692
3693 smp_wmb(); /* See comment in __pte_alloc */
3694
3695 spin_lock(&mm->page_table_lock);
3696 if (pgd_present(*pgd)) /* Another has populated it */
3697 pud_free(mm, new);
3698 else
3699 pgd_populate(mm, pgd, new);
3700 spin_unlock(&mm->page_table_lock);
3701 return 0;
3702 }
3703 #endif /* __PAGETABLE_PUD_FOLDED */
3704
3705 #ifndef __PAGETABLE_PMD_FOLDED
3706 /*
3707 * Allocate page middle directory.
3708 * We've already handled the fast-path in-line.
3709 */
3710 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3711 {
3712 pmd_t *new = pmd_alloc_one(mm, address);
3713 if (!new)
3714 return -ENOMEM;
3715
3716 smp_wmb(); /* See comment in __pte_alloc */
3717
3718 spin_lock(&mm->page_table_lock);
3719 #ifndef __ARCH_HAS_4LEVEL_HACK
3720 if (!pud_present(*pud)) {
3721 mm_inc_nr_pmds(mm);
3722 pud_populate(mm, pud, new);
3723 } else /* Another has populated it */
3724 pmd_free(mm, new);
3725 #else
3726 if (!pgd_present(*pud)) {
3727 mm_inc_nr_pmds(mm);
3728 pgd_populate(mm, pud, new);
3729 } else /* Another has populated it */
3730 pmd_free(mm, new);
3731 #endif /* __ARCH_HAS_4LEVEL_HACK */
3732 spin_unlock(&mm->page_table_lock);
3733 return 0;
3734 }
3735 #endif /* __PAGETABLE_PMD_FOLDED */
3736
3737 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3738 pte_t **ptepp, spinlock_t **ptlp)
3739 {
3740 pgd_t *pgd;
3741 pud_t *pud;
3742 pmd_t *pmd;
3743 pte_t *ptep;
3744
3745 pgd = pgd_offset(mm, address);
3746 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3747 goto out;
3748
3749 pud = pud_offset(pgd, address);
3750 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3751 goto out;
3752
3753 pmd = pmd_offset(pud, address);
3754 VM_BUG_ON(pmd_trans_huge(*pmd));
3755 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3756 goto out;
3757
3758 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3759 if (pmd_huge(*pmd))
3760 goto out;
3761
3762 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3763 if (!ptep)
3764 goto out;
3765 if (!pte_present(*ptep))
3766 goto unlock;
3767 *ptepp = ptep;
3768 return 0;
3769 unlock:
3770 pte_unmap_unlock(ptep, *ptlp);
3771 out:
3772 return -EINVAL;
3773 }
3774
3775 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3776 pte_t **ptepp, spinlock_t **ptlp)
3777 {
3778 int res;
3779
3780 /* (void) is needed to make gcc happy */
3781 (void) __cond_lock(*ptlp,
3782 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3783 return res;
3784 }
3785
3786 /**
3787 * follow_pfn - look up PFN at a user virtual address
3788 * @vma: memory mapping
3789 * @address: user virtual address
3790 * @pfn: location to store found PFN
3791 *
3792 * Only IO mappings and raw PFN mappings are allowed.
3793 *
3794 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3795 */
3796 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3797 unsigned long *pfn)
3798 {
3799 int ret = -EINVAL;
3800 spinlock_t *ptl;
3801 pte_t *ptep;
3802
3803 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3804 return ret;
3805
3806 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3807 if (ret)
3808 return ret;
3809 *pfn = pte_pfn(*ptep);
3810 pte_unmap_unlock(ptep, ptl);
3811 return 0;
3812 }
3813 EXPORT_SYMBOL(follow_pfn);
3814
3815 #ifdef CONFIG_HAVE_IOREMAP_PROT
3816 int follow_phys(struct vm_area_struct *vma,
3817 unsigned long address, unsigned int flags,
3818 unsigned long *prot, resource_size_t *phys)
3819 {
3820 int ret = -EINVAL;
3821 pte_t *ptep, pte;
3822 spinlock_t *ptl;
3823
3824 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3825 goto out;
3826
3827 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3828 goto out;
3829 pte = *ptep;
3830
3831 if ((flags & FOLL_WRITE) && !pte_write(pte))
3832 goto unlock;
3833
3834 *prot = pgprot_val(pte_pgprot(pte));
3835 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3836
3837 ret = 0;
3838 unlock:
3839 pte_unmap_unlock(ptep, ptl);
3840 out:
3841 return ret;
3842 }
3843
3844 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3845 void *buf, int len, int write)
3846 {
3847 resource_size_t phys_addr;
3848 unsigned long prot = 0;
3849 void __iomem *maddr;
3850 int offset = addr & (PAGE_SIZE-1);
3851
3852 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3853 return -EINVAL;
3854
3855 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3856 if (write)
3857 memcpy_toio(maddr + offset, buf, len);
3858 else
3859 memcpy_fromio(buf, maddr + offset, len);
3860 iounmap(maddr);
3861
3862 return len;
3863 }
3864 EXPORT_SYMBOL_GPL(generic_access_phys);
3865 #endif
3866
3867 /*
3868 * Access another process' address space as given in mm. If non-NULL, use the
3869 * given task for page fault accounting.
3870 */
3871 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3872 unsigned long addr, void *buf, int len, unsigned int gup_flags)
3873 {
3874 struct vm_area_struct *vma;
3875 void *old_buf = buf;
3876 int write = gup_flags & FOLL_WRITE;
3877
3878 down_read(&mm->mmap_sem);
3879 /* ignore errors, just check how much was successfully transferred */
3880 while (len) {
3881 int bytes, ret, offset;
3882 void *maddr;
3883 struct page *page = NULL;
3884
3885 ret = get_user_pages_remote(tsk, mm, addr, 1,
3886 gup_flags, &page, &vma);
3887 if (ret <= 0) {
3888 #ifndef CONFIG_HAVE_IOREMAP_PROT
3889 break;
3890 #else
3891 /*
3892 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3893 * we can access using slightly different code.
3894 */
3895 vma = find_vma(mm, addr);
3896 if (!vma || vma->vm_start > addr)
3897 break;
3898 if (vma->vm_ops && vma->vm_ops->access)
3899 ret = vma->vm_ops->access(vma, addr, buf,
3900 len, write);
3901 if (ret <= 0)
3902 break;
3903 bytes = ret;
3904 #endif
3905 } else {
3906 bytes = len;
3907 offset = addr & (PAGE_SIZE-1);
3908 if (bytes > PAGE_SIZE-offset)
3909 bytes = PAGE_SIZE-offset;
3910
3911 maddr = kmap(page);
3912 if (write) {
3913 copy_to_user_page(vma, page, addr,
3914 maddr + offset, buf, bytes);
3915 set_page_dirty_lock(page);
3916 } else {
3917 copy_from_user_page(vma, page, addr,
3918 buf, maddr + offset, bytes);
3919 }
3920 kunmap(page);
3921 put_page(page);
3922 }
3923 len -= bytes;
3924 buf += bytes;
3925 addr += bytes;
3926 }
3927 up_read(&mm->mmap_sem);
3928
3929 return buf - old_buf;
3930 }
3931
3932 /**
3933 * access_remote_vm - access another process' address space
3934 * @mm: the mm_struct of the target address space
3935 * @addr: start address to access
3936 * @buf: source or destination buffer
3937 * @len: number of bytes to transfer
3938 * @gup_flags: flags modifying lookup behaviour
3939 *
3940 * The caller must hold a reference on @mm.
3941 */
3942 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3943 void *buf, int len, unsigned int gup_flags)
3944 {
3945 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
3946 }
3947
3948 /*
3949 * Access another process' address space.
3950 * Source/target buffer must be kernel space,
3951 * Do not walk the page table directly, use get_user_pages
3952 */
3953 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3954 void *buf, int len, unsigned int gup_flags)
3955 {
3956 struct mm_struct *mm;
3957 int ret;
3958
3959 mm = get_task_mm(tsk);
3960 if (!mm)
3961 return 0;
3962
3963 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
3964
3965 mmput(mm);
3966
3967 return ret;
3968 }
3969
3970 /*
3971 * Print the name of a VMA.
3972 */
3973 void print_vma_addr(char *prefix, unsigned long ip)
3974 {
3975 struct mm_struct *mm = current->mm;
3976 struct vm_area_struct *vma;
3977
3978 /*
3979 * Do not print if we are in atomic
3980 * contexts (in exception stacks, etc.):
3981 */
3982 if (preempt_count())
3983 return;
3984
3985 down_read(&mm->mmap_sem);
3986 vma = find_vma(mm, ip);
3987 if (vma && vma->vm_file) {
3988 struct file *f = vma->vm_file;
3989 char *buf = (char *)__get_free_page(GFP_KERNEL);
3990 if (buf) {
3991 char *p;
3992
3993 p = file_path(f, buf, PAGE_SIZE);
3994 if (IS_ERR(p))
3995 p = "?";
3996 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3997 vma->vm_start,
3998 vma->vm_end - vma->vm_start);
3999 free_page((unsigned long)buf);
4000 }
4001 }
4002 up_read(&mm->mmap_sem);
4003 }
4004
4005 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4006 void __might_fault(const char *file, int line)
4007 {
4008 /*
4009 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4010 * holding the mmap_sem, this is safe because kernel memory doesn't
4011 * get paged out, therefore we'll never actually fault, and the
4012 * below annotations will generate false positives.
4013 */
4014 if (segment_eq(get_fs(), KERNEL_DS))
4015 return;
4016 if (pagefault_disabled())
4017 return;
4018 __might_sleep(file, line, 0);
4019 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4020 if (current->mm)
4021 might_lock_read(&current->mm->mmap_sem);
4022 #endif
4023 }
4024 EXPORT_SYMBOL(__might_fault);
4025 #endif
4026
4027 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4028 static void clear_gigantic_page(struct page *page,
4029 unsigned long addr,
4030 unsigned int pages_per_huge_page)
4031 {
4032 int i;
4033 struct page *p = page;
4034
4035 might_sleep();
4036 for (i = 0; i < pages_per_huge_page;
4037 i++, p = mem_map_next(p, page, i)) {
4038 cond_resched();
4039 clear_user_highpage(p, addr + i * PAGE_SIZE);
4040 }
4041 }
4042 void clear_huge_page(struct page *page,
4043 unsigned long addr, unsigned int pages_per_huge_page)
4044 {
4045 int i;
4046
4047 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4048 clear_gigantic_page(page, addr, pages_per_huge_page);
4049 return;
4050 }
4051
4052 might_sleep();
4053 for (i = 0; i < pages_per_huge_page; i++) {
4054 cond_resched();
4055 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4056 }
4057 }
4058
4059 static void copy_user_gigantic_page(struct page *dst, struct page *src,
4060 unsigned long addr,
4061 struct vm_area_struct *vma,
4062 unsigned int pages_per_huge_page)
4063 {
4064 int i;
4065 struct page *dst_base = dst;
4066 struct page *src_base = src;
4067
4068 for (i = 0; i < pages_per_huge_page; ) {
4069 cond_resched();
4070 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4071
4072 i++;
4073 dst = mem_map_next(dst, dst_base, i);
4074 src = mem_map_next(src, src_base, i);
4075 }
4076 }
4077
4078 void copy_user_huge_page(struct page *dst, struct page *src,
4079 unsigned long addr, struct vm_area_struct *vma,
4080 unsigned int pages_per_huge_page)
4081 {
4082 int i;
4083
4084 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4085 copy_user_gigantic_page(dst, src, addr, vma,
4086 pages_per_huge_page);
4087 return;
4088 }
4089
4090 might_sleep();
4091 for (i = 0; i < pages_per_huge_page; i++) {
4092 cond_resched();
4093 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4094 }
4095 }
4096 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4097
4098 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4099
4100 static struct kmem_cache *page_ptl_cachep;
4101
4102 void __init ptlock_cache_init(void)
4103 {
4104 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4105 SLAB_PANIC, NULL);
4106 }
4107
4108 bool ptlock_alloc(struct page *page)
4109 {
4110 spinlock_t *ptl;
4111
4112 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4113 if (!ptl)
4114 return false;
4115 page->ptl = ptl;
4116 return true;
4117 }
4118
4119 void ptlock_free(struct page *page)
4120 {
4121 kmem_cache_free(page_ptl_cachep, page->ptl);
4122 }
4123 #endif