Root/
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/writeback.h> |
54 | #include <linux/memcontrol.h> |
55 | #include <linux/mmu_notifier.h> |
56 | #include <linux/kallsyms.h> |
57 | #include <linux/swapops.h> |
58 | #include <linux/elf.h> |
59 | #include <linux/gfp.h> |
60 | #include <linux/migrate.h> |
61 | #include <linux/string.h> |
62 | |
63 | #include <asm/io.h> |
64 | #include <asm/pgalloc.h> |
65 | #include <asm/uaccess.h> |
66 | #include <asm/tlb.h> |
67 | #include <asm/tlbflush.h> |
68 | #include <asm/pgtable.h> |
69 | |
70 | #include "internal.h" |
71 | |
72 | #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS |
73 | #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. |
74 | #endif |
75 | |
76 | #ifndef CONFIG_NEED_MULTIPLE_NODES |
77 | /* use the per-pgdat data instead for discontigmem - mbligh */ |
78 | unsigned long max_mapnr; |
79 | struct page *mem_map; |
80 | |
81 | EXPORT_SYMBOL(max_mapnr); |
82 | EXPORT_SYMBOL(mem_map); |
83 | #endif |
84 | |
85 | /* |
86 | * A number of key systems in x86 including ioremap() rely on the assumption |
87 | * that high_memory defines the upper bound on direct map memory, then end |
88 | * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and |
89 | * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL |
90 | * and ZONE_HIGHMEM. |
91 | */ |
92 | void * high_memory; |
93 | |
94 | EXPORT_SYMBOL(high_memory); |
95 | |
96 | /* |
97 | * Randomize the address space (stacks, mmaps, brk, etc.). |
98 | * |
99 | * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, |
100 | * as ancient (libc5 based) binaries can segfault. ) |
101 | */ |
102 | int randomize_va_space __read_mostly = |
103 | #ifdef CONFIG_COMPAT_BRK |
104 | 1; |
105 | #else |
106 | 2; |
107 | #endif |
108 | |
109 | static int __init disable_randmaps(char *s) |
110 | { |
111 | randomize_va_space = 0; |
112 | return 1; |
113 | } |
114 | __setup("norandmaps", disable_randmaps); |
115 | |
116 | unsigned long zero_pfn __read_mostly; |
117 | unsigned long highest_memmap_pfn __read_mostly; |
118 | |
119 | /* |
120 | * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() |
121 | */ |
122 | static int __init init_zero_pfn(void) |
123 | { |
124 | zero_pfn = page_to_pfn(ZERO_PAGE(0)); |
125 | return 0; |
126 | } |
127 | core_initcall(init_zero_pfn); |
128 | |
129 | |
130 | #if defined(SPLIT_RSS_COUNTING) |
131 | |
132 | void sync_mm_rss(struct mm_struct *mm) |
133 | { |
134 | int i; |
135 | |
136 | for (i = 0; i < NR_MM_COUNTERS; i++) { |
137 | if (current->rss_stat.count[i]) { |
138 | add_mm_counter(mm, i, current->rss_stat.count[i]); |
139 | current->rss_stat.count[i] = 0; |
140 | } |
141 | } |
142 | current->rss_stat.events = 0; |
143 | } |
144 | |
145 | static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) |
146 | { |
147 | struct task_struct *task = current; |
148 | |
149 | if (likely(task->mm == mm)) |
150 | task->rss_stat.count[member] += val; |
151 | else |
152 | add_mm_counter(mm, member, val); |
153 | } |
154 | #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) |
155 | #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) |
156 | |
157 | /* sync counter once per 64 page faults */ |
158 | #define TASK_RSS_EVENTS_THRESH (64) |
159 | static void check_sync_rss_stat(struct task_struct *task) |
160 | { |
161 | if (unlikely(task != current)) |
162 | return; |
163 | if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) |
164 | sync_mm_rss(task->mm); |
165 | } |
166 | #else /* SPLIT_RSS_COUNTING */ |
167 | |
168 | #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) |
169 | #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) |
170 | |
171 | static void check_sync_rss_stat(struct task_struct *task) |
172 | { |
173 | } |
174 | |
175 | #endif /* SPLIT_RSS_COUNTING */ |
176 | |
177 | #ifdef HAVE_GENERIC_MMU_GATHER |
178 | |
179 | static int tlb_next_batch(struct mmu_gather *tlb) |
180 | { |
181 | struct mmu_gather_batch *batch; |
182 | |
183 | batch = tlb->active; |
184 | if (batch->next) { |
185 | tlb->active = batch->next; |
186 | return 1; |
187 | } |
188 | |
189 | if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) |
190 | return 0; |
191 | |
192 | batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); |
193 | if (!batch) |
194 | return 0; |
195 | |
196 | tlb->batch_count++; |
197 | batch->next = NULL; |
198 | batch->nr = 0; |
199 | batch->max = MAX_GATHER_BATCH; |
200 | |
201 | tlb->active->next = batch; |
202 | tlb->active = batch; |
203 | |
204 | return 1; |
205 | } |
206 | |
207 | /* tlb_gather_mmu |
208 | * Called to initialize an (on-stack) mmu_gather structure for page-table |
209 | * tear-down from @mm. The @fullmm argument is used when @mm is without |
210 | * users and we're going to destroy the full address space (exit/execve). |
211 | */ |
212 | void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end) |
213 | { |
214 | tlb->mm = mm; |
215 | |
216 | /* Is it from 0 to ~0? */ |
217 | tlb->fullmm = !(start | (end+1)); |
218 | tlb->need_flush_all = 0; |
219 | tlb->start = start; |
220 | tlb->end = end; |
221 | tlb->need_flush = 0; |
222 | tlb->local.next = NULL; |
223 | tlb->local.nr = 0; |
224 | tlb->local.max = ARRAY_SIZE(tlb->__pages); |
225 | tlb->active = &tlb->local; |
226 | tlb->batch_count = 0; |
227 | |
228 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
229 | tlb->batch = NULL; |
230 | #endif |
231 | } |
232 | |
233 | void tlb_flush_mmu(struct mmu_gather *tlb) |
234 | { |
235 | struct mmu_gather_batch *batch; |
236 | |
237 | if (!tlb->need_flush) |
238 | return; |
239 | tlb->need_flush = 0; |
240 | tlb_flush(tlb); |
241 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
242 | tlb_table_flush(tlb); |
243 | #endif |
244 | |
245 | for (batch = &tlb->local; batch; batch = batch->next) { |
246 | free_pages_and_swap_cache(batch->pages, batch->nr); |
247 | batch->nr = 0; |
248 | } |
249 | tlb->active = &tlb->local; |
250 | } |
251 | |
252 | /* tlb_finish_mmu |
253 | * Called at the end of the shootdown operation to free up any resources |
254 | * that were required. |
255 | */ |
256 | void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) |
257 | { |
258 | struct mmu_gather_batch *batch, *next; |
259 | |
260 | tlb_flush_mmu(tlb); |
261 | |
262 | /* keep the page table cache within bounds */ |
263 | check_pgt_cache(); |
264 | |
265 | for (batch = tlb->local.next; batch; batch = next) { |
266 | next = batch->next; |
267 | free_pages((unsigned long)batch, 0); |
268 | } |
269 | tlb->local.next = NULL; |
270 | } |
271 | |
272 | /* __tlb_remove_page |
273 | * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while |
274 | * handling the additional races in SMP caused by other CPUs caching valid |
275 | * mappings in their TLBs. Returns the number of free page slots left. |
276 | * When out of page slots we must call tlb_flush_mmu(). |
277 | */ |
278 | int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) |
279 | { |
280 | struct mmu_gather_batch *batch; |
281 | |
282 | VM_BUG_ON(!tlb->need_flush); |
283 | |
284 | batch = tlb->active; |
285 | batch->pages[batch->nr++] = page; |
286 | if (batch->nr == batch->max) { |
287 | if (!tlb_next_batch(tlb)) |
288 | return 0; |
289 | batch = tlb->active; |
290 | } |
291 | VM_BUG_ON(batch->nr > batch->max); |
292 | |
293 | return batch->max - batch->nr; |
294 | } |
295 | |
296 | #endif /* HAVE_GENERIC_MMU_GATHER */ |
297 | |
298 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
299 | |
300 | /* |
301 | * See the comment near struct mmu_table_batch. |
302 | */ |
303 | |
304 | static void tlb_remove_table_smp_sync(void *arg) |
305 | { |
306 | /* Simply deliver the interrupt */ |
307 | } |
308 | |
309 | static void tlb_remove_table_one(void *table) |
310 | { |
311 | /* |
312 | * This isn't an RCU grace period and hence the page-tables cannot be |
313 | * assumed to be actually RCU-freed. |
314 | * |
315 | * It is however sufficient for software page-table walkers that rely on |
316 | * IRQ disabling. See the comment near struct mmu_table_batch. |
317 | */ |
318 | smp_call_function(tlb_remove_table_smp_sync, NULL, 1); |
319 | __tlb_remove_table(table); |
320 | } |
321 | |
322 | static void tlb_remove_table_rcu(struct rcu_head *head) |
323 | { |
324 | struct mmu_table_batch *batch; |
325 | int i; |
326 | |
327 | batch = container_of(head, struct mmu_table_batch, rcu); |
328 | |
329 | for (i = 0; i < batch->nr; i++) |
330 | __tlb_remove_table(batch->tables[i]); |
331 | |
332 | free_page((unsigned long)batch); |
333 | } |
334 | |
335 | void tlb_table_flush(struct mmu_gather *tlb) |
336 | { |
337 | struct mmu_table_batch **batch = &tlb->batch; |
338 | |
339 | if (*batch) { |
340 | call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); |
341 | *batch = NULL; |
342 | } |
343 | } |
344 | |
345 | void tlb_remove_table(struct mmu_gather *tlb, void *table) |
346 | { |
347 | struct mmu_table_batch **batch = &tlb->batch; |
348 | |
349 | tlb->need_flush = 1; |
350 | |
351 | /* |
352 | * When there's less then two users of this mm there cannot be a |
353 | * concurrent page-table walk. |
354 | */ |
355 | if (atomic_read(&tlb->mm->mm_users) < 2) { |
356 | __tlb_remove_table(table); |
357 | return; |
358 | } |
359 | |
360 | if (*batch == NULL) { |
361 | *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); |
362 | if (*batch == NULL) { |
363 | tlb_remove_table_one(table); |
364 | return; |
365 | } |
366 | (*batch)->nr = 0; |
367 | } |
368 | (*batch)->tables[(*batch)->nr++] = table; |
369 | if ((*batch)->nr == MAX_TABLE_BATCH) |
370 | tlb_table_flush(tlb); |
371 | } |
372 | |
373 | #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ |
374 | |
375 | /* |
376 | * Note: this doesn't free the actual pages themselves. That |
377 | * has been handled earlier when unmapping all the memory regions. |
378 | */ |
379 | static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, |
380 | unsigned long addr) |
381 | { |
382 | pgtable_t token = pmd_pgtable(*pmd); |
383 | pmd_clear(pmd); |
384 | pte_free_tlb(tlb, token, addr); |
385 | atomic_long_dec(&tlb->mm->nr_ptes); |
386 | } |
387 | |
388 | static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
389 | unsigned long addr, unsigned long end, |
390 | unsigned long floor, unsigned long ceiling) |
391 | { |
392 | pmd_t *pmd; |
393 | unsigned long next; |
394 | unsigned long start; |
395 | |
396 | start = addr; |
397 | pmd = pmd_offset(pud, addr); |
398 | do { |
399 | next = pmd_addr_end(addr, end); |
400 | if (pmd_none_or_clear_bad(pmd)) |
401 | continue; |
402 | free_pte_range(tlb, pmd, addr); |
403 | } while (pmd++, addr = next, addr != end); |
404 | |
405 | start &= PUD_MASK; |
406 | if (start < floor) |
407 | return; |
408 | if (ceiling) { |
409 | ceiling &= PUD_MASK; |
410 | if (!ceiling) |
411 | return; |
412 | } |
413 | if (end - 1 > ceiling - 1) |
414 | return; |
415 | |
416 | pmd = pmd_offset(pud, start); |
417 | pud_clear(pud); |
418 | pmd_free_tlb(tlb, pmd, start); |
419 | } |
420 | |
421 | static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, |
422 | unsigned long addr, unsigned long end, |
423 | unsigned long floor, unsigned long ceiling) |
424 | { |
425 | pud_t *pud; |
426 | unsigned long next; |
427 | unsigned long start; |
428 | |
429 | start = addr; |
430 | pud = pud_offset(pgd, addr); |
431 | do { |
432 | next = pud_addr_end(addr, end); |
433 | if (pud_none_or_clear_bad(pud)) |
434 | continue; |
435 | free_pmd_range(tlb, pud, addr, next, floor, ceiling); |
436 | } while (pud++, addr = next, addr != end); |
437 | |
438 | start &= PGDIR_MASK; |
439 | if (start < floor) |
440 | return; |
441 | if (ceiling) { |
442 | ceiling &= PGDIR_MASK; |
443 | if (!ceiling) |
444 | return; |
445 | } |
446 | if (end - 1 > ceiling - 1) |
447 | return; |
448 | |
449 | pud = pud_offset(pgd, start); |
450 | pgd_clear(pgd); |
451 | pud_free_tlb(tlb, pud, start); |
452 | } |
453 | |
454 | /* |
455 | * This function frees user-level page tables of a process. |
456 | */ |
457 | void free_pgd_range(struct mmu_gather *tlb, |
458 | unsigned long addr, unsigned long end, |
459 | unsigned long floor, unsigned long ceiling) |
460 | { |
461 | pgd_t *pgd; |
462 | unsigned long next; |
463 | |
464 | /* |
465 | * The next few lines have given us lots of grief... |
466 | * |
467 | * Why are we testing PMD* at this top level? Because often |
468 | * there will be no work to do at all, and we'd prefer not to |
469 | * go all the way down to the bottom just to discover that. |
470 | * |
471 | * Why all these "- 1"s? Because 0 represents both the bottom |
472 | * of the address space and the top of it (using -1 for the |
473 | * top wouldn't help much: the masks would do the wrong thing). |
474 | * The rule is that addr 0 and floor 0 refer to the bottom of |
475 | * the address space, but end 0 and ceiling 0 refer to the top |
476 | * Comparisons need to use "end - 1" and "ceiling - 1" (though |
477 | * that end 0 case should be mythical). |
478 | * |
479 | * Wherever addr is brought up or ceiling brought down, we must |
480 | * be careful to reject "the opposite 0" before it confuses the |
481 | * subsequent tests. But what about where end is brought down |
482 | * by PMD_SIZE below? no, end can't go down to 0 there. |
483 | * |
484 | * Whereas we round start (addr) and ceiling down, by different |
485 | * masks at different levels, in order to test whether a table |
486 | * now has no other vmas using it, so can be freed, we don't |
487 | * bother to round floor or end up - the tests don't need that. |
488 | */ |
489 | |
490 | addr &= PMD_MASK; |
491 | if (addr < floor) { |
492 | addr += PMD_SIZE; |
493 | if (!addr) |
494 | return; |
495 | } |
496 | if (ceiling) { |
497 | ceiling &= PMD_MASK; |
498 | if (!ceiling) |
499 | return; |
500 | } |
501 | if (end - 1 > ceiling - 1) |
502 | end -= PMD_SIZE; |
503 | if (addr > end - 1) |
504 | return; |
505 | |
506 | pgd = pgd_offset(tlb->mm, addr); |
507 | do { |
508 | next = pgd_addr_end(addr, end); |
509 | if (pgd_none_or_clear_bad(pgd)) |
510 | continue; |
511 | free_pud_range(tlb, pgd, addr, next, floor, ceiling); |
512 | } while (pgd++, addr = next, addr != end); |
513 | } |
514 | |
515 | void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, |
516 | unsigned long floor, unsigned long ceiling) |
517 | { |
518 | while (vma) { |
519 | struct vm_area_struct *next = vma->vm_next; |
520 | unsigned long addr = vma->vm_start; |
521 | |
522 | /* |
523 | * Hide vma from rmap and truncate_pagecache before freeing |
524 | * pgtables |
525 | */ |
526 | unlink_anon_vmas(vma); |
527 | unlink_file_vma(vma); |
528 | |
529 | if (is_vm_hugetlb_page(vma)) { |
530 | hugetlb_free_pgd_range(tlb, addr, vma->vm_end, |
531 | floor, next? next->vm_start: ceiling); |
532 | } else { |
533 | /* |
534 | * Optimization: gather nearby vmas into one call down |
535 | */ |
536 | while (next && next->vm_start <= vma->vm_end + PMD_SIZE |
537 | && !is_vm_hugetlb_page(next)) { |
538 | vma = next; |
539 | next = vma->vm_next; |
540 | unlink_anon_vmas(vma); |
541 | unlink_file_vma(vma); |
542 | } |
543 | free_pgd_range(tlb, addr, vma->vm_end, |
544 | floor, next? next->vm_start: ceiling); |
545 | } |
546 | vma = next; |
547 | } |
548 | } |
549 | |
550 | int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, |
551 | pmd_t *pmd, unsigned long address) |
552 | { |
553 | spinlock_t *ptl; |
554 | pgtable_t new = pte_alloc_one(mm, address); |
555 | int wait_split_huge_page; |
556 | if (!new) |
557 | return -ENOMEM; |
558 | |
559 | /* |
560 | * Ensure all pte setup (eg. pte page lock and page clearing) are |
561 | * visible before the pte is made visible to other CPUs by being |
562 | * put into page tables. |
563 | * |
564 | * The other side of the story is the pointer chasing in the page |
565 | * table walking code (when walking the page table without locking; |
566 | * ie. most of the time). Fortunately, these data accesses consist |
567 | * of a chain of data-dependent loads, meaning most CPUs (alpha |
568 | * being the notable exception) will already guarantee loads are |
569 | * seen in-order. See the alpha page table accessors for the |
570 | * smp_read_barrier_depends() barriers in page table walking code. |
571 | */ |
572 | smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ |
573 | |
574 | ptl = pmd_lock(mm, pmd); |
575 | wait_split_huge_page = 0; |
576 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
577 | atomic_long_inc(&mm->nr_ptes); |
578 | pmd_populate(mm, pmd, new); |
579 | new = NULL; |
580 | } else if (unlikely(pmd_trans_splitting(*pmd))) |
581 | wait_split_huge_page = 1; |
582 | spin_unlock(ptl); |
583 | if (new) |
584 | pte_free(mm, new); |
585 | if (wait_split_huge_page) |
586 | wait_split_huge_page(vma->anon_vma, pmd); |
587 | return 0; |
588 | } |
589 | |
590 | int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) |
591 | { |
592 | pte_t *new = pte_alloc_one_kernel(&init_mm, address); |
593 | if (!new) |
594 | return -ENOMEM; |
595 | |
596 | smp_wmb(); /* See comment in __pte_alloc */ |
597 | |
598 | spin_lock(&init_mm.page_table_lock); |
599 | if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
600 | pmd_populate_kernel(&init_mm, pmd, new); |
601 | new = NULL; |
602 | } else |
603 | VM_BUG_ON(pmd_trans_splitting(*pmd)); |
604 | spin_unlock(&init_mm.page_table_lock); |
605 | if (new) |
606 | pte_free_kernel(&init_mm, new); |
607 | return 0; |
608 | } |
609 | |
610 | static inline void init_rss_vec(int *rss) |
611 | { |
612 | memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); |
613 | } |
614 | |
615 | static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) |
616 | { |
617 | int i; |
618 | |
619 | if (current->mm == mm) |
620 | sync_mm_rss(mm); |
621 | for (i = 0; i < NR_MM_COUNTERS; i++) |
622 | if (rss[i]) |
623 | add_mm_counter(mm, i, rss[i]); |
624 | } |
625 | |
626 | /* |
627 | * This function is called to print an error when a bad pte |
628 | * is found. For example, we might have a PFN-mapped pte in |
629 | * a region that doesn't allow it. |
630 | * |
631 | * The calling function must still handle the error. |
632 | */ |
633 | static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, |
634 | pte_t pte, struct page *page) |
635 | { |
636 | pgd_t *pgd = pgd_offset(vma->vm_mm, addr); |
637 | pud_t *pud = pud_offset(pgd, addr); |
638 | pmd_t *pmd = pmd_offset(pud, addr); |
639 | struct address_space *mapping; |
640 | pgoff_t index; |
641 | static unsigned long resume; |
642 | static unsigned long nr_shown; |
643 | static unsigned long nr_unshown; |
644 | |
645 | /* |
646 | * Allow a burst of 60 reports, then keep quiet for that minute; |
647 | * or allow a steady drip of one report per second. |
648 | */ |
649 | if (nr_shown == 60) { |
650 | if (time_before(jiffies, resume)) { |
651 | nr_unshown++; |
652 | return; |
653 | } |
654 | if (nr_unshown) { |
655 | printk(KERN_ALERT |
656 | "BUG: Bad page map: %lu messages suppressed\n", |
657 | nr_unshown); |
658 | nr_unshown = 0; |
659 | } |
660 | nr_shown = 0; |
661 | } |
662 | if (nr_shown++ == 0) |
663 | resume = jiffies + 60 * HZ; |
664 | |
665 | mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; |
666 | index = linear_page_index(vma, addr); |
667 | |
668 | printk(KERN_ALERT |
669 | "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", |
670 | current->comm, |
671 | (long long)pte_val(pte), (long long)pmd_val(*pmd)); |
672 | if (page) |
673 | dump_page(page); |
674 | printk(KERN_ALERT |
675 | "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", |
676 | (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); |
677 | /* |
678 | * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y |
679 | */ |
680 | if (vma->vm_ops) |
681 | printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n", |
682 | vma->vm_ops->fault); |
683 | if (vma->vm_file) |
684 | printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n", |
685 | vma->vm_file->f_op->mmap); |
686 | dump_stack(); |
687 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
688 | } |
689 | |
690 | static inline bool is_cow_mapping(vm_flags_t flags) |
691 | { |
692 | return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; |
693 | } |
694 | |
695 | /* |
696 | * vm_normal_page -- This function gets the "struct page" associated with a pte. |
697 | * |
698 | * "Special" mappings do not wish to be associated with a "struct page" (either |
699 | * it doesn't exist, or it exists but they don't want to touch it). In this |
700 | * case, NULL is returned here. "Normal" mappings do have a struct page. |
701 | * |
702 | * There are 2 broad cases. Firstly, an architecture may define a pte_special() |
703 | * pte bit, in which case this function is trivial. Secondly, an architecture |
704 | * may not have a spare pte bit, which requires a more complicated scheme, |
705 | * described below. |
706 | * |
707 | * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a |
708 | * special mapping (even if there are underlying and valid "struct pages"). |
709 | * COWed pages of a VM_PFNMAP are always normal. |
710 | * |
711 | * The way we recognize COWed pages within VM_PFNMAP mappings is through the |
712 | * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit |
713 | * set, and the vm_pgoff will point to the first PFN mapped: thus every special |
714 | * mapping will always honor the rule |
715 | * |
716 | * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) |
717 | * |
718 | * And for normal mappings this is false. |
719 | * |
720 | * This restricts such mappings to be a linear translation from virtual address |
721 | * to pfn. To get around this restriction, we allow arbitrary mappings so long |
722 | * as the vma is not a COW mapping; in that case, we know that all ptes are |
723 | * special (because none can have been COWed). |
724 | * |
725 | * |
726 | * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. |
727 | * |
728 | * VM_MIXEDMAP mappings can likewise contain memory with or without "struct |
729 | * page" backing, however the difference is that _all_ pages with a struct |
730 | * page (that is, those where pfn_valid is true) are refcounted and considered |
731 | * normal pages by the VM. The disadvantage is that pages are refcounted |
732 | * (which can be slower and simply not an option for some PFNMAP users). The |
733 | * advantage is that we don't have to follow the strict linearity rule of |
734 | * PFNMAP mappings in order to support COWable mappings. |
735 | * |
736 | */ |
737 | #ifdef __HAVE_ARCH_PTE_SPECIAL |
738 | # define HAVE_PTE_SPECIAL 1 |
739 | #else |
740 | # define HAVE_PTE_SPECIAL 0 |
741 | #endif |
742 | struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, |
743 | pte_t pte) |
744 | { |
745 | unsigned long pfn = pte_pfn(pte); |
746 | |
747 | if (HAVE_PTE_SPECIAL) { |
748 | if (likely(!pte_special(pte))) |
749 | goto check_pfn; |
750 | if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
751 | return NULL; |
752 | if (!is_zero_pfn(pfn)) |
753 | print_bad_pte(vma, addr, pte, NULL); |
754 | return NULL; |
755 | } |
756 | |
757 | /* !HAVE_PTE_SPECIAL case follows: */ |
758 | |
759 | if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
760 | if (vma->vm_flags & VM_MIXEDMAP) { |
761 | if (!pfn_valid(pfn)) |
762 | return NULL; |
763 | goto out; |
764 | } else { |
765 | unsigned long off; |
766 | off = (addr - vma->vm_start) >> PAGE_SHIFT; |
767 | if (pfn == vma->vm_pgoff + off) |
768 | return NULL; |
769 | if (!is_cow_mapping(vma->vm_flags)) |
770 | return NULL; |
771 | } |
772 | } |
773 | |
774 | if (is_zero_pfn(pfn)) |
775 | return NULL; |
776 | check_pfn: |
777 | if (unlikely(pfn > highest_memmap_pfn)) { |
778 | print_bad_pte(vma, addr, pte, NULL); |
779 | return NULL; |
780 | } |
781 | |
782 | /* |
783 | * NOTE! We still have PageReserved() pages in the page tables. |
784 | * eg. VDSO mappings can cause them to exist. |
785 | */ |
786 | out: |
787 | return pfn_to_page(pfn); |
788 | } |
789 | |
790 | /* |
791 | * copy one vm_area from one task to the other. Assumes the page tables |
792 | * already present in the new task to be cleared in the whole range |
793 | * covered by this vma. |
794 | */ |
795 | |
796 | static inline unsigned long |
797 | copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
798 | pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, |
799 | unsigned long addr, int *rss) |
800 | { |
801 | unsigned long vm_flags = vma->vm_flags; |
802 | pte_t pte = *src_pte; |
803 | struct page *page; |
804 | |
805 | /* pte contains position in swap or file, so copy. */ |
806 | if (unlikely(!pte_present(pte))) { |
807 | if (!pte_file(pte)) { |
808 | swp_entry_t entry = pte_to_swp_entry(pte); |
809 | |
810 | if (swap_duplicate(entry) < 0) |
811 | return entry.val; |
812 | |
813 | /* make sure dst_mm is on swapoff's mmlist. */ |
814 | if (unlikely(list_empty(&dst_mm->mmlist))) { |
815 | spin_lock(&mmlist_lock); |
816 | if (list_empty(&dst_mm->mmlist)) |
817 | list_add(&dst_mm->mmlist, |
818 | &src_mm->mmlist); |
819 | spin_unlock(&mmlist_lock); |
820 | } |
821 | if (likely(!non_swap_entry(entry))) |
822 | rss[MM_SWAPENTS]++; |
823 | else if (is_migration_entry(entry)) { |
824 | page = migration_entry_to_page(entry); |
825 | |
826 | if (PageAnon(page)) |
827 | rss[MM_ANONPAGES]++; |
828 | else |
829 | rss[MM_FILEPAGES]++; |
830 | |
831 | if (is_write_migration_entry(entry) && |
832 | is_cow_mapping(vm_flags)) { |
833 | /* |
834 | * COW mappings require pages in both |
835 | * parent and child to be set to read. |
836 | */ |
837 | make_migration_entry_read(&entry); |
838 | pte = swp_entry_to_pte(entry); |
839 | if (pte_swp_soft_dirty(*src_pte)) |
840 | pte = pte_swp_mksoft_dirty(pte); |
841 | set_pte_at(src_mm, addr, src_pte, pte); |
842 | } |
843 | } |
844 | } |
845 | goto out_set_pte; |
846 | } |
847 | |
848 | /* |
849 | * If it's a COW mapping, write protect it both |
850 | * in the parent and the child |
851 | */ |
852 | if (is_cow_mapping(vm_flags)) { |
853 | ptep_set_wrprotect(src_mm, addr, src_pte); |
854 | pte = pte_wrprotect(pte); |
855 | } |
856 | |
857 | /* |
858 | * If it's a shared mapping, mark it clean in |
859 | * the child |
860 | */ |
861 | if (vm_flags & VM_SHARED) |
862 | pte = pte_mkclean(pte); |
863 | pte = pte_mkold(pte); |
864 | |
865 | page = vm_normal_page(vma, addr, pte); |
866 | if (page) { |
867 | get_page(page); |
868 | page_dup_rmap(page); |
869 | if (PageAnon(page)) |
870 | rss[MM_ANONPAGES]++; |
871 | else |
872 | rss[MM_FILEPAGES]++; |
873 | } |
874 | |
875 | out_set_pte: |
876 | set_pte_at(dst_mm, addr, dst_pte, pte); |
877 | return 0; |
878 | } |
879 | |
880 | int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
881 | pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, |
882 | unsigned long addr, unsigned long end) |
883 | { |
884 | pte_t *orig_src_pte, *orig_dst_pte; |
885 | pte_t *src_pte, *dst_pte; |
886 | spinlock_t *src_ptl, *dst_ptl; |
887 | int progress = 0; |
888 | int rss[NR_MM_COUNTERS]; |
889 | swp_entry_t entry = (swp_entry_t){0}; |
890 | |
891 | again: |
892 | init_rss_vec(rss); |
893 | |
894 | dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); |
895 | if (!dst_pte) |
896 | return -ENOMEM; |
897 | src_pte = pte_offset_map(src_pmd, addr); |
898 | src_ptl = pte_lockptr(src_mm, src_pmd); |
899 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
900 | orig_src_pte = src_pte; |
901 | orig_dst_pte = dst_pte; |
902 | arch_enter_lazy_mmu_mode(); |
903 | |
904 | do { |
905 | /* |
906 | * We are holding two locks at this point - either of them |
907 | * could generate latencies in another task on another CPU. |
908 | */ |
909 | if (progress >= 32) { |
910 | progress = 0; |
911 | if (need_resched() || |
912 | spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) |
913 | break; |
914 | } |
915 | if (pte_none(*src_pte)) { |
916 | progress++; |
917 | continue; |
918 | } |
919 | entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, |
920 | vma, addr, rss); |
921 | if (entry.val) |
922 | break; |
923 | progress += 8; |
924 | } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); |
925 | |
926 | arch_leave_lazy_mmu_mode(); |
927 | spin_unlock(src_ptl); |
928 | pte_unmap(orig_src_pte); |
929 | add_mm_rss_vec(dst_mm, rss); |
930 | pte_unmap_unlock(orig_dst_pte, dst_ptl); |
931 | cond_resched(); |
932 | |
933 | if (entry.val) { |
934 | if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) |
935 | return -ENOMEM; |
936 | progress = 0; |
937 | } |
938 | if (addr != end) |
939 | goto again; |
940 | return 0; |
941 | } |
942 | |
943 | static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
944 | pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, |
945 | unsigned long addr, unsigned long end) |
946 | { |
947 | pmd_t *src_pmd, *dst_pmd; |
948 | unsigned long next; |
949 | |
950 | dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); |
951 | if (!dst_pmd) |
952 | return -ENOMEM; |
953 | src_pmd = pmd_offset(src_pud, addr); |
954 | do { |
955 | next = pmd_addr_end(addr, end); |
956 | if (pmd_trans_huge(*src_pmd)) { |
957 | int err; |
958 | VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); |
959 | err = copy_huge_pmd(dst_mm, src_mm, |
960 | dst_pmd, src_pmd, addr, vma); |
961 | if (err == -ENOMEM) |
962 | return -ENOMEM; |
963 | if (!err) |
964 | continue; |
965 | /* fall through */ |
966 | } |
967 | if (pmd_none_or_clear_bad(src_pmd)) |
968 | continue; |
969 | if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, |
970 | vma, addr, next)) |
971 | return -ENOMEM; |
972 | } while (dst_pmd++, src_pmd++, addr = next, addr != end); |
973 | return 0; |
974 | } |
975 | |
976 | static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
977 | pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, |
978 | unsigned long addr, unsigned long end) |
979 | { |
980 | pud_t *src_pud, *dst_pud; |
981 | unsigned long next; |
982 | |
983 | dst_pud = pud_alloc(dst_mm, dst_pgd, addr); |
984 | if (!dst_pud) |
985 | return -ENOMEM; |
986 | src_pud = pud_offset(src_pgd, addr); |
987 | do { |
988 | next = pud_addr_end(addr, end); |
989 | if (pud_none_or_clear_bad(src_pud)) |
990 | continue; |
991 | if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, |
992 | vma, addr, next)) |
993 | return -ENOMEM; |
994 | } while (dst_pud++, src_pud++, addr = next, addr != end); |
995 | return 0; |
996 | } |
997 | |
998 | int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
999 | struct vm_area_struct *vma) |
1000 | { |
1001 | pgd_t *src_pgd, *dst_pgd; |
1002 | unsigned long next; |
1003 | unsigned long addr = vma->vm_start; |
1004 | unsigned long end = vma->vm_end; |
1005 | unsigned long mmun_start; /* For mmu_notifiers */ |
1006 | unsigned long mmun_end; /* For mmu_notifiers */ |
1007 | bool is_cow; |
1008 | int ret; |
1009 | |
1010 | /* |
1011 | * Don't copy ptes where a page fault will fill them correctly. |
1012 | * Fork becomes much lighter when there are big shared or private |
1013 | * readonly mappings. The tradeoff is that copy_page_range is more |
1014 | * efficient than faulting. |
1015 | */ |
1016 | if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR | |
1017 | VM_PFNMAP | VM_MIXEDMAP))) { |
1018 | if (!vma->anon_vma) |
1019 | return 0; |
1020 | } |
1021 | |
1022 | if (is_vm_hugetlb_page(vma)) |
1023 | return copy_hugetlb_page_range(dst_mm, src_mm, vma); |
1024 | |
1025 | if (unlikely(vma->vm_flags & VM_PFNMAP)) { |
1026 | /* |
1027 | * We do not free on error cases below as remove_vma |
1028 | * gets called on error from higher level routine |
1029 | */ |
1030 | ret = track_pfn_copy(vma); |
1031 | if (ret) |
1032 | return ret; |
1033 | } |
1034 | |
1035 | /* |
1036 | * We need to invalidate the secondary MMU mappings only when |
1037 | * there could be a permission downgrade on the ptes of the |
1038 | * parent mm. And a permission downgrade will only happen if |
1039 | * is_cow_mapping() returns true. |
1040 | */ |
1041 | is_cow = is_cow_mapping(vma->vm_flags); |
1042 | mmun_start = addr; |
1043 | mmun_end = end; |
1044 | if (is_cow) |
1045 | mmu_notifier_invalidate_range_start(src_mm, mmun_start, |
1046 | mmun_end); |
1047 | |
1048 | ret = 0; |
1049 | dst_pgd = pgd_offset(dst_mm, addr); |
1050 | src_pgd = pgd_offset(src_mm, addr); |
1051 | do { |
1052 | next = pgd_addr_end(addr, end); |
1053 | if (pgd_none_or_clear_bad(src_pgd)) |
1054 | continue; |
1055 | if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, |
1056 | vma, addr, next))) { |
1057 | ret = -ENOMEM; |
1058 | break; |
1059 | } |
1060 | } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
1061 | |
1062 | if (is_cow) |
1063 | mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); |
1064 | return ret; |
1065 | } |
1066 | |
1067 | static unsigned long zap_pte_range(struct mmu_gather *tlb, |
1068 | struct vm_area_struct *vma, pmd_t *pmd, |
1069 | unsigned long addr, unsigned long end, |
1070 | struct zap_details *details) |
1071 | { |
1072 | struct mm_struct *mm = tlb->mm; |
1073 | int force_flush = 0; |
1074 | int rss[NR_MM_COUNTERS]; |
1075 | spinlock_t *ptl; |
1076 | pte_t *start_pte; |
1077 | pte_t *pte; |
1078 | |
1079 | again: |
1080 | init_rss_vec(rss); |
1081 | start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
1082 | pte = start_pte; |
1083 | arch_enter_lazy_mmu_mode(); |
1084 | do { |
1085 | pte_t ptent = *pte; |
1086 | if (pte_none(ptent)) { |
1087 | continue; |
1088 | } |
1089 | |
1090 | if (pte_present(ptent)) { |
1091 | struct page *page; |
1092 | |
1093 | page = vm_normal_page(vma, addr, ptent); |
1094 | if (unlikely(details) && page) { |
1095 | /* |
1096 | * unmap_shared_mapping_pages() wants to |
1097 | * invalidate cache without truncating: |
1098 | * unmap shared but keep private pages. |
1099 | */ |
1100 | if (details->check_mapping && |
1101 | details->check_mapping != page->mapping) |
1102 | continue; |
1103 | /* |
1104 | * Each page->index must be checked when |
1105 | * invalidating or truncating nonlinear. |
1106 | */ |
1107 | if (details->nonlinear_vma && |
1108 | (page->index < details->first_index || |
1109 | page->index > details->last_index)) |
1110 | continue; |
1111 | } |
1112 | ptent = ptep_get_and_clear_full(mm, addr, pte, |
1113 | tlb->fullmm); |
1114 | tlb_remove_tlb_entry(tlb, pte, addr); |
1115 | if (unlikely(!page)) |
1116 | continue; |
1117 | if (unlikely(details) && details->nonlinear_vma |
1118 | && linear_page_index(details->nonlinear_vma, |
1119 | addr) != page->index) { |
1120 | pte_t ptfile = pgoff_to_pte(page->index); |
1121 | if (pte_soft_dirty(ptent)) |
1122 | pte_file_mksoft_dirty(ptfile); |
1123 | set_pte_at(mm, addr, pte, ptfile); |
1124 | } |
1125 | if (PageAnon(page)) |
1126 | rss[MM_ANONPAGES]--; |
1127 | else { |
1128 | if (pte_dirty(ptent)) |
1129 | set_page_dirty(page); |
1130 | if (pte_young(ptent) && |
1131 | likely(!(vma->vm_flags & VM_SEQ_READ))) |
1132 | mark_page_accessed(page); |
1133 | rss[MM_FILEPAGES]--; |
1134 | } |
1135 | page_remove_rmap(page); |
1136 | if (unlikely(page_mapcount(page) < 0)) |
1137 | print_bad_pte(vma, addr, ptent, page); |
1138 | force_flush = !__tlb_remove_page(tlb, page); |
1139 | if (force_flush) |
1140 | break; |
1141 | continue; |
1142 | } |
1143 | /* |
1144 | * If details->check_mapping, we leave swap entries; |
1145 | * if details->nonlinear_vma, we leave file entries. |
1146 | */ |
1147 | if (unlikely(details)) |
1148 | continue; |
1149 | if (pte_file(ptent)) { |
1150 | if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) |
1151 | print_bad_pte(vma, addr, ptent, NULL); |
1152 | } else { |
1153 | swp_entry_t entry = pte_to_swp_entry(ptent); |
1154 | |
1155 | if (!non_swap_entry(entry)) |
1156 | rss[MM_SWAPENTS]--; |
1157 | else if (is_migration_entry(entry)) { |
1158 | struct page *page; |
1159 | |
1160 | page = migration_entry_to_page(entry); |
1161 | |
1162 | if (PageAnon(page)) |
1163 | rss[MM_ANONPAGES]--; |
1164 | else |
1165 | rss[MM_FILEPAGES]--; |
1166 | } |
1167 | if (unlikely(!free_swap_and_cache(entry))) |
1168 | print_bad_pte(vma, addr, ptent, NULL); |
1169 | } |
1170 | pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); |
1171 | } while (pte++, addr += PAGE_SIZE, addr != end); |
1172 | |
1173 | add_mm_rss_vec(mm, rss); |
1174 | arch_leave_lazy_mmu_mode(); |
1175 | pte_unmap_unlock(start_pte, ptl); |
1176 | |
1177 | /* |
1178 | * mmu_gather ran out of room to batch pages, we break out of |
1179 | * the PTE lock to avoid doing the potential expensive TLB invalidate |
1180 | * and page-free while holding it. |
1181 | */ |
1182 | if (force_flush) { |
1183 | unsigned long old_end; |
1184 | |
1185 | force_flush = 0; |
1186 | |
1187 | /* |
1188 | * Flush the TLB just for the previous segment, |
1189 | * then update the range to be the remaining |
1190 | * TLB range. |
1191 | */ |
1192 | old_end = tlb->end; |
1193 | tlb->end = addr; |
1194 | |
1195 | tlb_flush_mmu(tlb); |
1196 | |
1197 | tlb->start = addr; |
1198 | tlb->end = old_end; |
1199 | |
1200 | if (addr != end) |
1201 | goto again; |
1202 | } |
1203 | |
1204 | return addr; |
1205 | } |
1206 | |
1207 | static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, |
1208 | struct vm_area_struct *vma, pud_t *pud, |
1209 | unsigned long addr, unsigned long end, |
1210 | struct zap_details *details) |
1211 | { |
1212 | pmd_t *pmd; |
1213 | unsigned long next; |
1214 | |
1215 | pmd = pmd_offset(pud, addr); |
1216 | do { |
1217 | next = pmd_addr_end(addr, end); |
1218 | if (pmd_trans_huge(*pmd)) { |
1219 | if (next - addr != HPAGE_PMD_SIZE) { |
1220 | #ifdef CONFIG_DEBUG_VM |
1221 | if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { |
1222 | pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n", |
1223 | __func__, addr, end, |
1224 | vma->vm_start, |
1225 | vma->vm_end); |
1226 | BUG(); |
1227 | } |
1228 | #endif |
1229 | split_huge_page_pmd(vma, addr, pmd); |
1230 | } else if (zap_huge_pmd(tlb, vma, pmd, addr)) |
1231 | goto next; |
1232 | /* fall through */ |
1233 | } |
1234 | /* |
1235 | * Here there can be other concurrent MADV_DONTNEED or |
1236 | * trans huge page faults running, and if the pmd is |
1237 | * none or trans huge it can change under us. This is |
1238 | * because MADV_DONTNEED holds the mmap_sem in read |
1239 | * mode. |
1240 | */ |
1241 | if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
1242 | goto next; |
1243 | next = zap_pte_range(tlb, vma, pmd, addr, next, details); |
1244 | next: |
1245 | cond_resched(); |
1246 | } while (pmd++, addr = next, addr != end); |
1247 | |
1248 | return addr; |
1249 | } |
1250 | |
1251 | static inline unsigned long zap_pud_range(struct mmu_gather *tlb, |
1252 | struct vm_area_struct *vma, pgd_t *pgd, |
1253 | unsigned long addr, unsigned long end, |
1254 | struct zap_details *details) |
1255 | { |
1256 | pud_t *pud; |
1257 | unsigned long next; |
1258 | |
1259 | pud = pud_offset(pgd, addr); |
1260 | do { |
1261 | next = pud_addr_end(addr, end); |
1262 | if (pud_none_or_clear_bad(pud)) |
1263 | continue; |
1264 | next = zap_pmd_range(tlb, vma, pud, addr, next, details); |
1265 | } while (pud++, addr = next, addr != end); |
1266 | |
1267 | return addr; |
1268 | } |
1269 | |
1270 | static void unmap_page_range(struct mmu_gather *tlb, |
1271 | struct vm_area_struct *vma, |
1272 | unsigned long addr, unsigned long end, |
1273 | struct zap_details *details) |
1274 | { |
1275 | pgd_t *pgd; |
1276 | unsigned long next; |
1277 | |
1278 | if (details && !details->check_mapping && !details->nonlinear_vma) |
1279 | details = NULL; |
1280 | |
1281 | BUG_ON(addr >= end); |
1282 | mem_cgroup_uncharge_start(); |
1283 | tlb_start_vma(tlb, vma); |
1284 | pgd = pgd_offset(vma->vm_mm, addr); |
1285 | do { |
1286 | next = pgd_addr_end(addr, end); |
1287 | if (pgd_none_or_clear_bad(pgd)) |
1288 | continue; |
1289 | next = zap_pud_range(tlb, vma, pgd, addr, next, details); |
1290 | } while (pgd++, addr = next, addr != end); |
1291 | tlb_end_vma(tlb, vma); |
1292 | mem_cgroup_uncharge_end(); |
1293 | } |
1294 | |
1295 | |
1296 | static void unmap_single_vma(struct mmu_gather *tlb, |
1297 | struct vm_area_struct *vma, unsigned long start_addr, |
1298 | unsigned long end_addr, |
1299 | struct zap_details *details) |
1300 | { |
1301 | unsigned long start = max(vma->vm_start, start_addr); |
1302 | unsigned long end; |
1303 | |
1304 | if (start >= vma->vm_end) |
1305 | return; |
1306 | end = min(vma->vm_end, end_addr); |
1307 | if (end <= vma->vm_start) |
1308 | return; |
1309 | |
1310 | if (vma->vm_file) |
1311 | uprobe_munmap(vma, start, end); |
1312 | |
1313 | if (unlikely(vma->vm_flags & VM_PFNMAP)) |
1314 | untrack_pfn(vma, 0, 0); |
1315 | |
1316 | if (start != end) { |
1317 | if (unlikely(is_vm_hugetlb_page(vma))) { |
1318 | /* |
1319 | * It is undesirable to test vma->vm_file as it |
1320 | * should be non-null for valid hugetlb area. |
1321 | * However, vm_file will be NULL in the error |
1322 | * cleanup path of do_mmap_pgoff. When |
1323 | * hugetlbfs ->mmap method fails, |
1324 | * do_mmap_pgoff() nullifies vma->vm_file |
1325 | * before calling this function to clean up. |
1326 | * Since no pte has actually been setup, it is |
1327 | * safe to do nothing in this case. |
1328 | */ |
1329 | if (vma->vm_file) { |
1330 | mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); |
1331 | __unmap_hugepage_range_final(tlb, vma, start, end, NULL); |
1332 | mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); |
1333 | } |
1334 | } else |
1335 | unmap_page_range(tlb, vma, start, end, details); |
1336 | } |
1337 | } |
1338 | |
1339 | /** |
1340 | * unmap_vmas - unmap a range of memory covered by a list of vma's |
1341 | * @tlb: address of the caller's struct mmu_gather |
1342 | * @vma: the starting vma |
1343 | * @start_addr: virtual address at which to start unmapping |
1344 | * @end_addr: virtual address at which to end unmapping |
1345 | * |
1346 | * Unmap all pages in the vma list. |
1347 | * |
1348 | * Only addresses between `start' and `end' will be unmapped. |
1349 | * |
1350 | * The VMA list must be sorted in ascending virtual address order. |
1351 | * |
1352 | * unmap_vmas() assumes that the caller will flush the whole unmapped address |
1353 | * range after unmap_vmas() returns. So the only responsibility here is to |
1354 | * ensure that any thus-far unmapped pages are flushed before unmap_vmas() |
1355 | * drops the lock and schedules. |
1356 | */ |
1357 | void unmap_vmas(struct mmu_gather *tlb, |
1358 | struct vm_area_struct *vma, unsigned long start_addr, |
1359 | unsigned long end_addr) |
1360 | { |
1361 | struct mm_struct *mm = vma->vm_mm; |
1362 | |
1363 | mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); |
1364 | for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) |
1365 | unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); |
1366 | mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); |
1367 | } |
1368 | |
1369 | /** |
1370 | * zap_page_range - remove user pages in a given range |
1371 | * @vma: vm_area_struct holding the applicable pages |
1372 | * @start: starting address of pages to zap |
1373 | * @size: number of bytes to zap |
1374 | * @details: details of nonlinear truncation or shared cache invalidation |
1375 | * |
1376 | * Caller must protect the VMA list |
1377 | */ |
1378 | void zap_page_range(struct vm_area_struct *vma, unsigned long start, |
1379 | unsigned long size, struct zap_details *details) |
1380 | { |
1381 | struct mm_struct *mm = vma->vm_mm; |
1382 | struct mmu_gather tlb; |
1383 | unsigned long end = start + size; |
1384 | |
1385 | lru_add_drain(); |
1386 | tlb_gather_mmu(&tlb, mm, start, end); |
1387 | update_hiwater_rss(mm); |
1388 | mmu_notifier_invalidate_range_start(mm, start, end); |
1389 | for ( ; vma && vma->vm_start < end; vma = vma->vm_next) |
1390 | unmap_single_vma(&tlb, vma, start, end, details); |
1391 | mmu_notifier_invalidate_range_end(mm, start, end); |
1392 | tlb_finish_mmu(&tlb, start, end); |
1393 | } |
1394 | |
1395 | /** |
1396 | * zap_page_range_single - remove user pages in a given range |
1397 | * @vma: vm_area_struct holding the applicable pages |
1398 | * @address: starting address of pages to zap |
1399 | * @size: number of bytes to zap |
1400 | * @details: details of nonlinear truncation or shared cache invalidation |
1401 | * |
1402 | * The range must fit into one VMA. |
1403 | */ |
1404 | static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, |
1405 | unsigned long size, struct zap_details *details) |
1406 | { |
1407 | struct mm_struct *mm = vma->vm_mm; |
1408 | struct mmu_gather tlb; |
1409 | unsigned long end = address + size; |
1410 | |
1411 | lru_add_drain(); |
1412 | tlb_gather_mmu(&tlb, mm, address, end); |
1413 | update_hiwater_rss(mm); |
1414 | mmu_notifier_invalidate_range_start(mm, address, end); |
1415 | unmap_single_vma(&tlb, vma, address, end, details); |
1416 | mmu_notifier_invalidate_range_end(mm, address, end); |
1417 | tlb_finish_mmu(&tlb, address, end); |
1418 | } |
1419 | |
1420 | /** |
1421 | * zap_vma_ptes - remove ptes mapping the vma |
1422 | * @vma: vm_area_struct holding ptes to be zapped |
1423 | * @address: starting address of pages to zap |
1424 | * @size: number of bytes to zap |
1425 | * |
1426 | * This function only unmaps ptes assigned to VM_PFNMAP vmas. |
1427 | * |
1428 | * The entire address range must be fully contained within the vma. |
1429 | * |
1430 | * Returns 0 if successful. |
1431 | */ |
1432 | int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, |
1433 | unsigned long size) |
1434 | { |
1435 | if (address < vma->vm_start || address + size > vma->vm_end || |
1436 | !(vma->vm_flags & VM_PFNMAP)) |
1437 | return -1; |
1438 | zap_page_range_single(vma, address, size, NULL); |
1439 | return 0; |
1440 | } |
1441 | EXPORT_SYMBOL_GPL(zap_vma_ptes); |
1442 | |
1443 | /** |
1444 | * follow_page_mask - look up a page descriptor from a user-virtual address |
1445 | * @vma: vm_area_struct mapping @address |
1446 | * @address: virtual address to look up |
1447 | * @flags: flags modifying lookup behaviour |
1448 | * @page_mask: on output, *page_mask is set according to the size of the page |
1449 | * |
1450 | * @flags can have FOLL_ flags set, defined in <linux/mm.h> |
1451 | * |
1452 | * Returns the mapped (struct page *), %NULL if no mapping exists, or |
1453 | * an error pointer if there is a mapping to something not represented |
1454 | * by a page descriptor (see also vm_normal_page()). |
1455 | */ |
1456 | struct page *follow_page_mask(struct vm_area_struct *vma, |
1457 | unsigned long address, unsigned int flags, |
1458 | unsigned int *page_mask) |
1459 | { |
1460 | pgd_t *pgd; |
1461 | pud_t *pud; |
1462 | pmd_t *pmd; |
1463 | pte_t *ptep, pte; |
1464 | spinlock_t *ptl; |
1465 | struct page *page; |
1466 | struct mm_struct *mm = vma->vm_mm; |
1467 | |
1468 | *page_mask = 0; |
1469 | |
1470 | page = follow_huge_addr(mm, address, flags & FOLL_WRITE); |
1471 | if (!IS_ERR(page)) { |
1472 | BUG_ON(flags & FOLL_GET); |
1473 | goto out; |
1474 | } |
1475 | |
1476 | page = NULL; |
1477 | pgd = pgd_offset(mm, address); |
1478 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
1479 | goto no_page_table; |
1480 | |
1481 | pud = pud_offset(pgd, address); |
1482 | if (pud_none(*pud)) |
1483 | goto no_page_table; |
1484 | if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { |
1485 | if (flags & FOLL_GET) |
1486 | goto out; |
1487 | page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); |
1488 | goto out; |
1489 | } |
1490 | if (unlikely(pud_bad(*pud))) |
1491 | goto no_page_table; |
1492 | |
1493 | pmd = pmd_offset(pud, address); |
1494 | if (pmd_none(*pmd)) |
1495 | goto no_page_table; |
1496 | if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { |
1497 | page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); |
1498 | if (flags & FOLL_GET) { |
1499 | /* |
1500 | * Refcount on tail pages are not well-defined and |
1501 | * shouldn't be taken. The caller should handle a NULL |
1502 | * return when trying to follow tail pages. |
1503 | */ |
1504 | if (PageHead(page)) |
1505 | get_page(page); |
1506 | else { |
1507 | page = NULL; |
1508 | goto out; |
1509 | } |
1510 | } |
1511 | goto out; |
1512 | } |
1513 | if ((flags & FOLL_NUMA) && pmd_numa(*pmd)) |
1514 | goto no_page_table; |
1515 | if (pmd_trans_huge(*pmd)) { |
1516 | if (flags & FOLL_SPLIT) { |
1517 | split_huge_page_pmd(vma, address, pmd); |
1518 | goto split_fallthrough; |
1519 | } |
1520 | ptl = pmd_lock(mm, pmd); |
1521 | if (likely(pmd_trans_huge(*pmd))) { |
1522 | if (unlikely(pmd_trans_splitting(*pmd))) { |
1523 | spin_unlock(ptl); |
1524 | wait_split_huge_page(vma->anon_vma, pmd); |
1525 | } else { |
1526 | page = follow_trans_huge_pmd(vma, address, |
1527 | pmd, flags); |
1528 | spin_unlock(ptl); |
1529 | *page_mask = HPAGE_PMD_NR - 1; |
1530 | goto out; |
1531 | } |
1532 | } else |
1533 | spin_unlock(ptl); |
1534 | /* fall through */ |
1535 | } |
1536 | split_fallthrough: |
1537 | if (unlikely(pmd_bad(*pmd))) |
1538 | goto no_page_table; |
1539 | |
1540 | ptep = pte_offset_map_lock(mm, pmd, address, &ptl); |
1541 | |
1542 | pte = *ptep; |
1543 | if (!pte_present(pte)) { |
1544 | swp_entry_t entry; |
1545 | /* |
1546 | * KSM's break_ksm() relies upon recognizing a ksm page |
1547 | * even while it is being migrated, so for that case we |
1548 | * need migration_entry_wait(). |
1549 | */ |
1550 | if (likely(!(flags & FOLL_MIGRATION))) |
1551 | goto no_page; |
1552 | if (pte_none(pte) || pte_file(pte)) |
1553 | goto no_page; |
1554 | entry = pte_to_swp_entry(pte); |
1555 | if (!is_migration_entry(entry)) |
1556 | goto no_page; |
1557 | pte_unmap_unlock(ptep, ptl); |
1558 | migration_entry_wait(mm, pmd, address); |
1559 | goto split_fallthrough; |
1560 | } |
1561 | if ((flags & FOLL_NUMA) && pte_numa(pte)) |
1562 | goto no_page; |
1563 | if ((flags & FOLL_WRITE) && !pte_write(pte)) |
1564 | goto unlock; |
1565 | |
1566 | page = vm_normal_page(vma, address, pte); |
1567 | if (unlikely(!page)) { |
1568 | if ((flags & FOLL_DUMP) || |
1569 | !is_zero_pfn(pte_pfn(pte))) |
1570 | goto bad_page; |
1571 | page = pte_page(pte); |
1572 | } |
1573 | |
1574 | if (flags & FOLL_GET) |
1575 | get_page_foll(page); |
1576 | if (flags & FOLL_TOUCH) { |
1577 | if ((flags & FOLL_WRITE) && |
1578 | !pte_dirty(pte) && !PageDirty(page)) |
1579 | set_page_dirty(page); |
1580 | /* |
1581 | * pte_mkyoung() would be more correct here, but atomic care |
1582 | * is needed to avoid losing the dirty bit: it is easier to use |
1583 | * mark_page_accessed(). |
1584 | */ |
1585 | mark_page_accessed(page); |
1586 | } |
1587 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
1588 | /* |
1589 | * The preliminary mapping check is mainly to avoid the |
1590 | * pointless overhead of lock_page on the ZERO_PAGE |
1591 | * which might bounce very badly if there is contention. |
1592 | * |
1593 | * If the page is already locked, we don't need to |
1594 | * handle it now - vmscan will handle it later if and |
1595 | * when it attempts to reclaim the page. |
1596 | */ |
1597 | if (page->mapping && trylock_page(page)) { |
1598 | lru_add_drain(); /* push cached pages to LRU */ |
1599 | /* |
1600 | * Because we lock page here, and migration is |
1601 | * blocked by the pte's page reference, and we |
1602 | * know the page is still mapped, we don't even |
1603 | * need to check for file-cache page truncation. |
1604 | */ |
1605 | mlock_vma_page(page); |
1606 | unlock_page(page); |
1607 | } |
1608 | } |
1609 | unlock: |
1610 | pte_unmap_unlock(ptep, ptl); |
1611 | out: |
1612 | return page; |
1613 | |
1614 | bad_page: |
1615 | pte_unmap_unlock(ptep, ptl); |
1616 | return ERR_PTR(-EFAULT); |
1617 | |
1618 | no_page: |
1619 | pte_unmap_unlock(ptep, ptl); |
1620 | if (!pte_none(pte)) |
1621 | return page; |
1622 | |
1623 | no_page_table: |
1624 | /* |
1625 | * When core dumping an enormous anonymous area that nobody |
1626 | * has touched so far, we don't want to allocate unnecessary pages or |
1627 | * page tables. Return error instead of NULL to skip handle_mm_fault, |
1628 | * then get_dump_page() will return NULL to leave a hole in the dump. |
1629 | * But we can only make this optimization where a hole would surely |
1630 | * be zero-filled if handle_mm_fault() actually did handle it. |
1631 | */ |
1632 | if ((flags & FOLL_DUMP) && |
1633 | (!vma->vm_ops || !vma->vm_ops->fault)) |
1634 | return ERR_PTR(-EFAULT); |
1635 | return page; |
1636 | } |
1637 | |
1638 | static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) |
1639 | { |
1640 | return stack_guard_page_start(vma, addr) || |
1641 | stack_guard_page_end(vma, addr+PAGE_SIZE); |
1642 | } |
1643 | |
1644 | /** |
1645 | * __get_user_pages() - pin user pages in memory |
1646 | * @tsk: task_struct of target task |
1647 | * @mm: mm_struct of target mm |
1648 | * @start: starting user address |
1649 | * @nr_pages: number of pages from start to pin |
1650 | * @gup_flags: flags modifying pin behaviour |
1651 | * @pages: array that receives pointers to the pages pinned. |
1652 | * Should be at least nr_pages long. Or NULL, if caller |
1653 | * only intends to ensure the pages are faulted in. |
1654 | * @vmas: array of pointers to vmas corresponding to each page. |
1655 | * Or NULL if the caller does not require them. |
1656 | * @nonblocking: whether waiting for disk IO or mmap_sem contention |
1657 | * |
1658 | * Returns number of pages pinned. This may be fewer than the number |
1659 | * requested. If nr_pages is 0 or negative, returns 0. If no pages |
1660 | * were pinned, returns -errno. Each page returned must be released |
1661 | * with a put_page() call when it is finished with. vmas will only |
1662 | * remain valid while mmap_sem is held. |
1663 | * |
1664 | * Must be called with mmap_sem held for read or write. |
1665 | * |
1666 | * __get_user_pages walks a process's page tables and takes a reference to |
1667 | * each struct page that each user address corresponds to at a given |
1668 | * instant. That is, it takes the page that would be accessed if a user |
1669 | * thread accesses the given user virtual address at that instant. |
1670 | * |
1671 | * This does not guarantee that the page exists in the user mappings when |
1672 | * __get_user_pages returns, and there may even be a completely different |
1673 | * page there in some cases (eg. if mmapped pagecache has been invalidated |
1674 | * and subsequently re faulted). However it does guarantee that the page |
1675 | * won't be freed completely. And mostly callers simply care that the page |
1676 | * contains data that was valid *at some point in time*. Typically, an IO |
1677 | * or similar operation cannot guarantee anything stronger anyway because |
1678 | * locks can't be held over the syscall boundary. |
1679 | * |
1680 | * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If |
1681 | * the page is written to, set_page_dirty (or set_page_dirty_lock, as |
1682 | * appropriate) must be called after the page is finished with, and |
1683 | * before put_page is called. |
1684 | * |
1685 | * If @nonblocking != NULL, __get_user_pages will not wait for disk IO |
1686 | * or mmap_sem contention, and if waiting is needed to pin all pages, |
1687 | * *@nonblocking will be set to 0. |
1688 | * |
1689 | * In most cases, get_user_pages or get_user_pages_fast should be used |
1690 | * instead of __get_user_pages. __get_user_pages should be used only if |
1691 | * you need some special @gup_flags. |
1692 | */ |
1693 | long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
1694 | unsigned long start, unsigned long nr_pages, |
1695 | unsigned int gup_flags, struct page **pages, |
1696 | struct vm_area_struct **vmas, int *nonblocking) |
1697 | { |
1698 | long i; |
1699 | unsigned long vm_flags; |
1700 | unsigned int page_mask; |
1701 | |
1702 | if (!nr_pages) |
1703 | return 0; |
1704 | |
1705 | VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); |
1706 | |
1707 | /* |
1708 | * Require read or write permissions. |
1709 | * If FOLL_FORCE is set, we only require the "MAY" flags. |
1710 | */ |
1711 | vm_flags = (gup_flags & FOLL_WRITE) ? |
1712 | (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); |
1713 | vm_flags &= (gup_flags & FOLL_FORCE) ? |
1714 | (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); |
1715 | |
1716 | /* |
1717 | * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault |
1718 | * would be called on PROT_NONE ranges. We must never invoke |
1719 | * handle_mm_fault on PROT_NONE ranges or the NUMA hinting |
1720 | * page faults would unprotect the PROT_NONE ranges if |
1721 | * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd |
1722 | * bitflag. So to avoid that, don't set FOLL_NUMA if |
1723 | * FOLL_FORCE is set. |
1724 | */ |
1725 | if (!(gup_flags & FOLL_FORCE)) |
1726 | gup_flags |= FOLL_NUMA; |
1727 | |
1728 | i = 0; |
1729 | |
1730 | do { |
1731 | struct vm_area_struct *vma; |
1732 | |
1733 | vma = find_extend_vma(mm, start); |
1734 | if (!vma && in_gate_area(mm, start)) { |
1735 | unsigned long pg = start & PAGE_MASK; |
1736 | pgd_t *pgd; |
1737 | pud_t *pud; |
1738 | pmd_t *pmd; |
1739 | pte_t *pte; |
1740 | |
1741 | /* user gate pages are read-only */ |
1742 | if (gup_flags & FOLL_WRITE) |
1743 | return i ? : -EFAULT; |
1744 | if (pg > TASK_SIZE) |
1745 | pgd = pgd_offset_k(pg); |
1746 | else |
1747 | pgd = pgd_offset_gate(mm, pg); |
1748 | BUG_ON(pgd_none(*pgd)); |
1749 | pud = pud_offset(pgd, pg); |
1750 | BUG_ON(pud_none(*pud)); |
1751 | pmd = pmd_offset(pud, pg); |
1752 | if (pmd_none(*pmd)) |
1753 | return i ? : -EFAULT; |
1754 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
1755 | pte = pte_offset_map(pmd, pg); |
1756 | if (pte_none(*pte)) { |
1757 | pte_unmap(pte); |
1758 | return i ? : -EFAULT; |
1759 | } |
1760 | vma = get_gate_vma(mm); |
1761 | if (pages) { |
1762 | struct page *page; |
1763 | |
1764 | page = vm_normal_page(vma, start, *pte); |
1765 | if (!page) { |
1766 | if (!(gup_flags & FOLL_DUMP) && |
1767 | is_zero_pfn(pte_pfn(*pte))) |
1768 | page = pte_page(*pte); |
1769 | else { |
1770 | pte_unmap(pte); |
1771 | return i ? : -EFAULT; |
1772 | } |
1773 | } |
1774 | pages[i] = page; |
1775 | get_page(page); |
1776 | } |
1777 | pte_unmap(pte); |
1778 | page_mask = 0; |
1779 | goto next_page; |
1780 | } |
1781 | |
1782 | if (!vma || |
1783 | (vma->vm_flags & (VM_IO | VM_PFNMAP)) || |
1784 | !(vm_flags & vma->vm_flags)) |
1785 | return i ? : -EFAULT; |
1786 | |
1787 | if (is_vm_hugetlb_page(vma)) { |
1788 | i = follow_hugetlb_page(mm, vma, pages, vmas, |
1789 | &start, &nr_pages, i, gup_flags); |
1790 | continue; |
1791 | } |
1792 | |
1793 | do { |
1794 | struct page *page; |
1795 | unsigned int foll_flags = gup_flags; |
1796 | unsigned int page_increm; |
1797 | |
1798 | /* |
1799 | * If we have a pending SIGKILL, don't keep faulting |
1800 | * pages and potentially allocating memory. |
1801 | */ |
1802 | if (unlikely(fatal_signal_pending(current))) |
1803 | return i ? i : -ERESTARTSYS; |
1804 | |
1805 | cond_resched(); |
1806 | while (!(page = follow_page_mask(vma, start, |
1807 | foll_flags, &page_mask))) { |
1808 | int ret; |
1809 | unsigned int fault_flags = 0; |
1810 | |
1811 | /* For mlock, just skip the stack guard page. */ |
1812 | if (foll_flags & FOLL_MLOCK) { |
1813 | if (stack_guard_page(vma, start)) |
1814 | goto next_page; |
1815 | } |
1816 | if (foll_flags & FOLL_WRITE) |
1817 | fault_flags |= FAULT_FLAG_WRITE; |
1818 | if (nonblocking) |
1819 | fault_flags |= FAULT_FLAG_ALLOW_RETRY; |
1820 | if (foll_flags & FOLL_NOWAIT) |
1821 | fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT); |
1822 | |
1823 | ret = handle_mm_fault(mm, vma, start, |
1824 | fault_flags); |
1825 | |
1826 | if (ret & VM_FAULT_ERROR) { |
1827 | if (ret & VM_FAULT_OOM) |
1828 | return i ? i : -ENOMEM; |
1829 | if (ret & (VM_FAULT_HWPOISON | |
1830 | VM_FAULT_HWPOISON_LARGE)) { |
1831 | if (i) |
1832 | return i; |
1833 | else if (gup_flags & FOLL_HWPOISON) |
1834 | return -EHWPOISON; |
1835 | else |
1836 | return -EFAULT; |
1837 | } |
1838 | if (ret & VM_FAULT_SIGBUS) |
1839 | return i ? i : -EFAULT; |
1840 | BUG(); |
1841 | } |
1842 | |
1843 | if (tsk) { |
1844 | if (ret & VM_FAULT_MAJOR) |
1845 | tsk->maj_flt++; |
1846 | else |
1847 | tsk->min_flt++; |
1848 | } |
1849 | |
1850 | if (ret & VM_FAULT_RETRY) { |
1851 | if (nonblocking) |
1852 | *nonblocking = 0; |
1853 | return i; |
1854 | } |
1855 | |
1856 | /* |
1857 | * The VM_FAULT_WRITE bit tells us that |
1858 | * do_wp_page has broken COW when necessary, |
1859 | * even if maybe_mkwrite decided not to set |
1860 | * pte_write. We can thus safely do subsequent |
1861 | * page lookups as if they were reads. But only |
1862 | * do so when looping for pte_write is futile: |
1863 | * in some cases userspace may also be wanting |
1864 | * to write to the gotten user page, which a |
1865 | * read fault here might prevent (a readonly |
1866 | * page might get reCOWed by userspace write). |
1867 | */ |
1868 | if ((ret & VM_FAULT_WRITE) && |
1869 | !(vma->vm_flags & VM_WRITE)) |
1870 | foll_flags &= ~FOLL_WRITE; |
1871 | |
1872 | cond_resched(); |
1873 | } |
1874 | if (IS_ERR(page)) |
1875 | return i ? i : PTR_ERR(page); |
1876 | if (pages) { |
1877 | pages[i] = page; |
1878 | |
1879 | flush_anon_page(vma, page, start); |
1880 | flush_dcache_page(page); |
1881 | page_mask = 0; |
1882 | } |
1883 | next_page: |
1884 | if (vmas) { |
1885 | vmas[i] = vma; |
1886 | page_mask = 0; |
1887 | } |
1888 | page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask); |
1889 | if (page_increm > nr_pages) |
1890 | page_increm = nr_pages; |
1891 | i += page_increm; |
1892 | start += page_increm * PAGE_SIZE; |
1893 | nr_pages -= page_increm; |
1894 | } while (nr_pages && start < vma->vm_end); |
1895 | } while (nr_pages); |
1896 | return i; |
1897 | } |
1898 | EXPORT_SYMBOL(__get_user_pages); |
1899 | |
1900 | /* |
1901 | * fixup_user_fault() - manually resolve a user page fault |
1902 | * @tsk: the task_struct to use for page fault accounting, or |
1903 | * NULL if faults are not to be recorded. |
1904 | * @mm: mm_struct of target mm |
1905 | * @address: user address |
1906 | * @fault_flags:flags to pass down to handle_mm_fault() |
1907 | * |
1908 | * This is meant to be called in the specific scenario where for locking reasons |
1909 | * we try to access user memory in atomic context (within a pagefault_disable() |
1910 | * section), this returns -EFAULT, and we want to resolve the user fault before |
1911 | * trying again. |
1912 | * |
1913 | * Typically this is meant to be used by the futex code. |
1914 | * |
1915 | * The main difference with get_user_pages() is that this function will |
1916 | * unconditionally call handle_mm_fault() which will in turn perform all the |
1917 | * necessary SW fixup of the dirty and young bits in the PTE, while |
1918 | * handle_mm_fault() only guarantees to update these in the struct page. |
1919 | * |
1920 | * This is important for some architectures where those bits also gate the |
1921 | * access permission to the page because they are maintained in software. On |
1922 | * such architectures, gup() will not be enough to make a subsequent access |
1923 | * succeed. |
1924 | * |
1925 | * This should be called with the mm_sem held for read. |
1926 | */ |
1927 | int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, |
1928 | unsigned long address, unsigned int fault_flags) |
1929 | { |
1930 | struct vm_area_struct *vma; |
1931 | int ret; |
1932 | |
1933 | vma = find_extend_vma(mm, address); |
1934 | if (!vma || address < vma->vm_start) |
1935 | return -EFAULT; |
1936 | |
1937 | ret = handle_mm_fault(mm, vma, address, fault_flags); |
1938 | if (ret & VM_FAULT_ERROR) { |
1939 | if (ret & VM_FAULT_OOM) |
1940 | return -ENOMEM; |
1941 | if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) |
1942 | return -EHWPOISON; |
1943 | if (ret & VM_FAULT_SIGBUS) |
1944 | return -EFAULT; |
1945 | BUG(); |
1946 | } |
1947 | if (tsk) { |
1948 | if (ret & VM_FAULT_MAJOR) |
1949 | tsk->maj_flt++; |
1950 | else |
1951 | tsk->min_flt++; |
1952 | } |
1953 | return 0; |
1954 | } |
1955 | |
1956 | /* |
1957 | * get_user_pages() - pin user pages in memory |
1958 | * @tsk: the task_struct to use for page fault accounting, or |
1959 | * NULL if faults are not to be recorded. |
1960 | * @mm: mm_struct of target mm |
1961 | * @start: starting user address |
1962 | * @nr_pages: number of pages from start to pin |
1963 | * @write: whether pages will be written to by the caller |
1964 | * @force: whether to force write access even if user mapping is |
1965 | * readonly. This will result in the page being COWed even |
1966 | * in MAP_SHARED mappings. You do not want this. |
1967 | * @pages: array that receives pointers to the pages pinned. |
1968 | * Should be at least nr_pages long. Or NULL, if caller |
1969 | * only intends to ensure the pages are faulted in. |
1970 | * @vmas: array of pointers to vmas corresponding to each page. |
1971 | * Or NULL if the caller does not require them. |
1972 | * |
1973 | * Returns number of pages pinned. This may be fewer than the number |
1974 | * requested. If nr_pages is 0 or negative, returns 0. If no pages |
1975 | * were pinned, returns -errno. Each page returned must be released |
1976 | * with a put_page() call when it is finished with. vmas will only |
1977 | * remain valid while mmap_sem is held. |
1978 | * |
1979 | * Must be called with mmap_sem held for read or write. |
1980 | * |
1981 | * get_user_pages walks a process's page tables and takes a reference to |
1982 | * each struct page that each user address corresponds to at a given |
1983 | * instant. That is, it takes the page that would be accessed if a user |
1984 | * thread accesses the given user virtual address at that instant. |
1985 | * |
1986 | * This does not guarantee that the page exists in the user mappings when |
1987 | * get_user_pages returns, and there may even be a completely different |
1988 | * page there in some cases (eg. if mmapped pagecache has been invalidated |
1989 | * and subsequently re faulted). However it does guarantee that the page |
1990 | * won't be freed completely. And mostly callers simply care that the page |
1991 | * contains data that was valid *at some point in time*. Typically, an IO |
1992 | * or similar operation cannot guarantee anything stronger anyway because |
1993 | * locks can't be held over the syscall boundary. |
1994 | * |
1995 | * If write=0, the page must not be written to. If the page is written to, |
1996 | * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called |
1997 | * after the page is finished with, and before put_page is called. |
1998 | * |
1999 | * get_user_pages is typically used for fewer-copy IO operations, to get a |
2000 | * handle on the memory by some means other than accesses via the user virtual |
2001 | * addresses. The pages may be submitted for DMA to devices or accessed via |
2002 | * their kernel linear mapping (via the kmap APIs). Care should be taken to |
2003 | * use the correct cache flushing APIs. |
2004 | * |
2005 | * See also get_user_pages_fast, for performance critical applications. |
2006 | */ |
2007 | long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
2008 | unsigned long start, unsigned long nr_pages, int write, |
2009 | int force, struct page **pages, struct vm_area_struct **vmas) |
2010 | { |
2011 | int flags = FOLL_TOUCH; |
2012 | |
2013 | if (pages) |
2014 | flags |= FOLL_GET; |
2015 | if (write) |
2016 | flags |= FOLL_WRITE; |
2017 | if (force) |
2018 | flags |= FOLL_FORCE; |
2019 | |
2020 | return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, |
2021 | NULL); |
2022 | } |
2023 | EXPORT_SYMBOL(get_user_pages); |
2024 | |
2025 | /** |
2026 | * get_dump_page() - pin user page in memory while writing it to core dump |
2027 | * @addr: user address |
2028 | * |
2029 | * Returns struct page pointer of user page pinned for dump, |
2030 | * to be freed afterwards by page_cache_release() or put_page(). |
2031 | * |
2032 | * Returns NULL on any kind of failure - a hole must then be inserted into |
2033 | * the corefile, to preserve alignment with its headers; and also returns |
2034 | * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - |
2035 | * allowing a hole to be left in the corefile to save diskspace. |
2036 | * |
2037 | * Called without mmap_sem, but after all other threads have been killed. |
2038 | */ |
2039 | #ifdef CONFIG_ELF_CORE |
2040 | struct page *get_dump_page(unsigned long addr) |
2041 | { |
2042 | struct vm_area_struct *vma; |
2043 | struct page *page; |
2044 | |
2045 | if (__get_user_pages(current, current->mm, addr, 1, |
2046 | FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma, |
2047 | NULL) < 1) |
2048 | return NULL; |
2049 | flush_cache_page(vma, addr, page_to_pfn(page)); |
2050 | return page; |
2051 | } |
2052 | #endif /* CONFIG_ELF_CORE */ |
2053 | |
2054 | pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, |
2055 | spinlock_t **ptl) |
2056 | { |
2057 | pgd_t * pgd = pgd_offset(mm, addr); |
2058 | pud_t * pud = pud_alloc(mm, pgd, addr); |
2059 | if (pud) { |
2060 | pmd_t * pmd = pmd_alloc(mm, pud, addr); |
2061 | if (pmd) { |
2062 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
2063 | return pte_alloc_map_lock(mm, pmd, addr, ptl); |
2064 | } |
2065 | } |
2066 | return NULL; |
2067 | } |
2068 | |
2069 | /* |
2070 | * This is the old fallback for page remapping. |
2071 | * |
2072 | * For historical reasons, it only allows reserved pages. Only |
2073 | * old drivers should use this, and they needed to mark their |
2074 | * pages reserved for the old functions anyway. |
2075 | */ |
2076 | static int insert_page(struct vm_area_struct *vma, unsigned long addr, |
2077 | struct page *page, pgprot_t prot) |
2078 | { |
2079 | struct mm_struct *mm = vma->vm_mm; |
2080 | int retval; |
2081 | pte_t *pte; |
2082 | spinlock_t *ptl; |
2083 | |
2084 | retval = -EINVAL; |
2085 | if (PageAnon(page)) |
2086 | goto out; |
2087 | retval = -ENOMEM; |
2088 | flush_dcache_page(page); |
2089 | pte = get_locked_pte(mm, addr, &ptl); |
2090 | if (!pte) |
2091 | goto out; |
2092 | retval = -EBUSY; |
2093 | if (!pte_none(*pte)) |
2094 | goto out_unlock; |
2095 | |
2096 | /* Ok, finally just insert the thing.. */ |
2097 | get_page(page); |
2098 | inc_mm_counter_fast(mm, MM_FILEPAGES); |
2099 | page_add_file_rmap(page); |
2100 | set_pte_at(mm, addr, pte, mk_pte(page, prot)); |
2101 | |
2102 | retval = 0; |
2103 | pte_unmap_unlock(pte, ptl); |
2104 | return retval; |
2105 | out_unlock: |
2106 | pte_unmap_unlock(pte, ptl); |
2107 | out: |
2108 | return retval; |
2109 | } |
2110 | |
2111 | /** |
2112 | * vm_insert_page - insert single page into user vma |
2113 | * @vma: user vma to map to |
2114 | * @addr: target user address of this page |
2115 | * @page: source kernel page |
2116 | * |
2117 | * This allows drivers to insert individual pages they've allocated |
2118 | * into a user vma. |
2119 | * |
2120 | * The page has to be a nice clean _individual_ kernel allocation. |
2121 | * If you allocate a compound page, you need to have marked it as |
2122 | * such (__GFP_COMP), or manually just split the page up yourself |
2123 | * (see split_page()). |
2124 | * |
2125 | * NOTE! Traditionally this was done with "remap_pfn_range()" which |
2126 | * took an arbitrary page protection parameter. This doesn't allow |
2127 | * that. Your vma protection will have to be set up correctly, which |
2128 | * means that if you want a shared writable mapping, you'd better |
2129 | * ask for a shared writable mapping! |
2130 | * |
2131 | * The page does not need to be reserved. |
2132 | * |
2133 | * Usually this function is called from f_op->mmap() handler |
2134 | * under mm->mmap_sem write-lock, so it can change vma->vm_flags. |
2135 | * Caller must set VM_MIXEDMAP on vma if it wants to call this |
2136 | * function from other places, for example from page-fault handler. |
2137 | */ |
2138 | int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
2139 | struct page *page) |
2140 | { |
2141 | if (addr < vma->vm_start || addr >= vma->vm_end) |
2142 | return -EFAULT; |
2143 | if (!page_count(page)) |
2144 | return -EINVAL; |
2145 | if (!(vma->vm_flags & VM_MIXEDMAP)) { |
2146 | BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); |
2147 | BUG_ON(vma->vm_flags & VM_PFNMAP); |
2148 | vma->vm_flags |= VM_MIXEDMAP; |
2149 | } |
2150 | return insert_page(vma, addr, page, vma->vm_page_prot); |
2151 | } |
2152 | EXPORT_SYMBOL(vm_insert_page); |
2153 | |
2154 | static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
2155 | unsigned long pfn, pgprot_t prot) |
2156 | { |
2157 | struct mm_struct *mm = vma->vm_mm; |
2158 | int retval; |
2159 | pte_t *pte, entry; |
2160 | spinlock_t *ptl; |
2161 | |
2162 | retval = -ENOMEM; |
2163 | pte = get_locked_pte(mm, addr, &ptl); |
2164 | if (!pte) |
2165 | goto out; |
2166 | retval = -EBUSY; |
2167 | if (!pte_none(*pte)) |
2168 | goto out_unlock; |
2169 | |
2170 | /* Ok, finally just insert the thing.. */ |
2171 | entry = pte_mkspecial(pfn_pte(pfn, prot)); |
2172 | set_pte_at(mm, addr, pte, entry); |
2173 | update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ |
2174 | |
2175 | retval = 0; |
2176 | out_unlock: |
2177 | pte_unmap_unlock(pte, ptl); |
2178 | out: |
2179 | return retval; |
2180 | } |
2181 | |
2182 | /** |
2183 | * vm_insert_pfn - insert single pfn into user vma |
2184 | * @vma: user vma to map to |
2185 | * @addr: target user address of this page |
2186 | * @pfn: source kernel pfn |
2187 | * |
2188 | * Similar to vm_insert_page, this allows drivers to insert individual pages |
2189 | * they've allocated into a user vma. Same comments apply. |
2190 | * |
2191 | * This function should only be called from a vm_ops->fault handler, and |
2192 | * in that case the handler should return NULL. |
2193 | * |
2194 | * vma cannot be a COW mapping. |
2195 | * |
2196 | * As this is called only for pages that do not currently exist, we |
2197 | * do not need to flush old virtual caches or the TLB. |
2198 | */ |
2199 | int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
2200 | unsigned long pfn) |
2201 | { |
2202 | int ret; |
2203 | pgprot_t pgprot = vma->vm_page_prot; |
2204 | /* |
2205 | * Technically, architectures with pte_special can avoid all these |
2206 | * restrictions (same for remap_pfn_range). However we would like |
2207 | * consistency in testing and feature parity among all, so we should |
2208 | * try to keep these invariants in place for everybody. |
2209 | */ |
2210 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); |
2211 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
2212 | (VM_PFNMAP|VM_MIXEDMAP)); |
2213 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
2214 | BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); |
2215 | |
2216 | if (addr < vma->vm_start || addr >= vma->vm_end) |
2217 | return -EFAULT; |
2218 | if (track_pfn_insert(vma, &pgprot, pfn)) |
2219 | return -EINVAL; |
2220 | |
2221 | ret = insert_pfn(vma, addr, pfn, pgprot); |
2222 | |
2223 | return ret; |
2224 | } |
2225 | EXPORT_SYMBOL(vm_insert_pfn); |
2226 | |
2227 | int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, |
2228 | unsigned long pfn) |
2229 | { |
2230 | BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); |
2231 | |
2232 | if (addr < vma->vm_start || addr >= vma->vm_end) |
2233 | return -EFAULT; |
2234 | |
2235 | /* |
2236 | * If we don't have pte special, then we have to use the pfn_valid() |
2237 | * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* |
2238 | * refcount the page if pfn_valid is true (hence insert_page rather |
2239 | * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP |
2240 | * without pte special, it would there be refcounted as a normal page. |
2241 | */ |
2242 | if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { |
2243 | struct page *page; |
2244 | |
2245 | page = pfn_to_page(pfn); |
2246 | return insert_page(vma, addr, page, vma->vm_page_prot); |
2247 | } |
2248 | return insert_pfn(vma, addr, pfn, vma->vm_page_prot); |
2249 | } |
2250 | EXPORT_SYMBOL(vm_insert_mixed); |
2251 | |
2252 | /* |
2253 | * maps a range of physical memory into the requested pages. the old |
2254 | * mappings are removed. any references to nonexistent pages results |
2255 | * in null mappings (currently treated as "copy-on-access") |
2256 | */ |
2257 | static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
2258 | unsigned long addr, unsigned long end, |
2259 | unsigned long pfn, pgprot_t prot) |
2260 | { |
2261 | pte_t *pte; |
2262 | spinlock_t *ptl; |
2263 | |
2264 | pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); |
2265 | if (!pte) |
2266 | return -ENOMEM; |
2267 | arch_enter_lazy_mmu_mode(); |
2268 | do { |
2269 | BUG_ON(!pte_none(*pte)); |
2270 | set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); |
2271 | pfn++; |
2272 | } while (pte++, addr += PAGE_SIZE, addr != end); |
2273 | arch_leave_lazy_mmu_mode(); |
2274 | pte_unmap_unlock(pte - 1, ptl); |
2275 | return 0; |
2276 | } |
2277 | |
2278 | static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, |
2279 | unsigned long addr, unsigned long end, |
2280 | unsigned long pfn, pgprot_t prot) |
2281 | { |
2282 | pmd_t *pmd; |
2283 | unsigned long next; |
2284 | |
2285 | pfn -= addr >> PAGE_SHIFT; |
2286 | pmd = pmd_alloc(mm, pud, addr); |
2287 | if (!pmd) |
2288 | return -ENOMEM; |
2289 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
2290 | do { |
2291 | next = pmd_addr_end(addr, end); |
2292 | if (remap_pte_range(mm, pmd, addr, next, |
2293 | pfn + (addr >> PAGE_SHIFT), prot)) |
2294 | return -ENOMEM; |
2295 | } while (pmd++, addr = next, addr != end); |
2296 | return 0; |
2297 | } |
2298 | |
2299 | static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, |
2300 | unsigned long addr, unsigned long end, |
2301 | unsigned long pfn, pgprot_t prot) |
2302 | { |
2303 | pud_t *pud; |
2304 | unsigned long next; |
2305 | |
2306 | pfn -= addr >> PAGE_SHIFT; |
2307 | pud = pud_alloc(mm, pgd, addr); |
2308 | if (!pud) |
2309 | return -ENOMEM; |
2310 | do { |
2311 | next = pud_addr_end(addr, end); |
2312 | if (remap_pmd_range(mm, pud, addr, next, |
2313 | pfn + (addr >> PAGE_SHIFT), prot)) |
2314 | return -ENOMEM; |
2315 | } while (pud++, addr = next, addr != end); |
2316 | return 0; |
2317 | } |
2318 | |
2319 | /** |
2320 | * remap_pfn_range - remap kernel memory to userspace |
2321 | * @vma: user vma to map to |
2322 | * @addr: target user address to start at |
2323 | * @pfn: physical address of kernel memory |
2324 | * @size: size of map area |
2325 | * @prot: page protection flags for this mapping |
2326 | * |
2327 | * Note: this is only safe if the mm semaphore is held when called. |
2328 | */ |
2329 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
2330 | unsigned long pfn, unsigned long size, pgprot_t prot) |
2331 | { |
2332 | pgd_t *pgd; |
2333 | unsigned long next; |
2334 | unsigned long end = addr + PAGE_ALIGN(size); |
2335 | struct mm_struct *mm = vma->vm_mm; |
2336 | int err; |
2337 | |
2338 | /* |
2339 | * Physically remapped pages are special. Tell the |
2340 | * rest of the world about it: |
2341 | * VM_IO tells people not to look at these pages |
2342 | * (accesses can have side effects). |
2343 | * VM_PFNMAP tells the core MM that the base pages are just |
2344 | * raw PFN mappings, and do not have a "struct page" associated |
2345 | * with them. |
2346 | * VM_DONTEXPAND |
2347 | * Disable vma merging and expanding with mremap(). |
2348 | * VM_DONTDUMP |
2349 | * Omit vma from core dump, even when VM_IO turned off. |
2350 | * |
2351 | * There's a horrible special case to handle copy-on-write |
2352 | * behaviour that some programs depend on. We mark the "original" |
2353 | * un-COW'ed pages by matching them up with "vma->vm_pgoff". |
2354 | * See vm_normal_page() for details. |
2355 | */ |
2356 | if (is_cow_mapping(vma->vm_flags)) { |
2357 | if (addr != vma->vm_start || end != vma->vm_end) |
2358 | return -EINVAL; |
2359 | vma->vm_pgoff = pfn; |
2360 | } |
2361 | |
2362 | err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); |
2363 | if (err) |
2364 | return -EINVAL; |
2365 | |
2366 | vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; |
2367 | |
2368 | BUG_ON(addr >= end); |
2369 | pfn -= addr >> PAGE_SHIFT; |
2370 | pgd = pgd_offset(mm, addr); |
2371 | flush_cache_range(vma, addr, end); |
2372 | do { |
2373 | next = pgd_addr_end(addr, end); |
2374 | err = remap_pud_range(mm, pgd, addr, next, |
2375 | pfn + (addr >> PAGE_SHIFT), prot); |
2376 | if (err) |
2377 | break; |
2378 | } while (pgd++, addr = next, addr != end); |
2379 | |
2380 | if (err) |
2381 | untrack_pfn(vma, pfn, PAGE_ALIGN(size)); |
2382 | |
2383 | return err; |
2384 | } |
2385 | EXPORT_SYMBOL(remap_pfn_range); |
2386 | |
2387 | /** |
2388 | * vm_iomap_memory - remap memory to userspace |
2389 | * @vma: user vma to map to |
2390 | * @start: start of area |
2391 | * @len: size of area |
2392 | * |
2393 | * This is a simplified io_remap_pfn_range() for common driver use. The |
2394 | * driver just needs to give us the physical memory range to be mapped, |
2395 | * we'll figure out the rest from the vma information. |
2396 | * |
2397 | * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get |
2398 | * whatever write-combining details or similar. |
2399 | */ |
2400 | int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
2401 | { |
2402 | unsigned long vm_len, pfn, pages; |
2403 | |
2404 | /* Check that the physical memory area passed in looks valid */ |
2405 | if (start + len < start) |
2406 | return -EINVAL; |
2407 | /* |
2408 | * You *really* shouldn't map things that aren't page-aligned, |
2409 | * but we've historically allowed it because IO memory might |
2410 | * just have smaller alignment. |
2411 | */ |
2412 | len += start & ~PAGE_MASK; |
2413 | pfn = start >> PAGE_SHIFT; |
2414 | pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; |
2415 | if (pfn + pages < pfn) |
2416 | return -EINVAL; |
2417 | |
2418 | /* We start the mapping 'vm_pgoff' pages into the area */ |
2419 | if (vma->vm_pgoff > pages) |
2420 | return -EINVAL; |
2421 | pfn += vma->vm_pgoff; |
2422 | pages -= vma->vm_pgoff; |
2423 | |
2424 | /* Can we fit all of the mapping? */ |
2425 | vm_len = vma->vm_end - vma->vm_start; |
2426 | if (vm_len >> PAGE_SHIFT > pages) |
2427 | return -EINVAL; |
2428 | |
2429 | /* Ok, let it rip */ |
2430 | return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
2431 | } |
2432 | EXPORT_SYMBOL(vm_iomap_memory); |
2433 | |
2434 | static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, |
2435 | unsigned long addr, unsigned long end, |
2436 | pte_fn_t fn, void *data) |
2437 | { |
2438 | pte_t *pte; |
2439 | int err; |
2440 | pgtable_t token; |
2441 | spinlock_t *uninitialized_var(ptl); |
2442 | |
2443 | pte = (mm == &init_mm) ? |
2444 | pte_alloc_kernel(pmd, addr) : |
2445 | pte_alloc_map_lock(mm, pmd, addr, &ptl); |
2446 | if (!pte) |
2447 | return -ENOMEM; |
2448 | |
2449 | BUG_ON(pmd_huge(*pmd)); |
2450 | |
2451 | arch_enter_lazy_mmu_mode(); |
2452 | |
2453 | token = pmd_pgtable(*pmd); |
2454 | |
2455 | do { |
2456 | err = fn(pte++, token, addr, data); |
2457 | if (err) |
2458 | break; |
2459 | } while (addr += PAGE_SIZE, addr != end); |
2460 | |
2461 | arch_leave_lazy_mmu_mode(); |
2462 | |
2463 | if (mm != &init_mm) |
2464 | pte_unmap_unlock(pte-1, ptl); |
2465 | return err; |
2466 | } |
2467 | |
2468 | static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, |
2469 | unsigned long addr, unsigned long end, |
2470 | pte_fn_t fn, void *data) |
2471 | { |
2472 | pmd_t *pmd; |
2473 | unsigned long next; |
2474 | int err; |
2475 | |
2476 | BUG_ON(pud_huge(*pud)); |
2477 | |
2478 | pmd = pmd_alloc(mm, pud, addr); |
2479 | if (!pmd) |
2480 | return -ENOMEM; |
2481 | do { |
2482 | next = pmd_addr_end(addr, end); |
2483 | err = apply_to_pte_range(mm, pmd, addr, next, fn, data); |
2484 | if (err) |
2485 | break; |
2486 | } while (pmd++, addr = next, addr != end); |
2487 | return err; |
2488 | } |
2489 | |
2490 | static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, |
2491 | unsigned long addr, unsigned long end, |
2492 | pte_fn_t fn, void *data) |
2493 | { |
2494 | pud_t *pud; |
2495 | unsigned long next; |
2496 | int err; |
2497 | |
2498 | pud = pud_alloc(mm, pgd, addr); |
2499 | if (!pud) |
2500 | return -ENOMEM; |
2501 | do { |
2502 | next = pud_addr_end(addr, end); |
2503 | err = apply_to_pmd_range(mm, pud, addr, next, fn, data); |
2504 | if (err) |
2505 | break; |
2506 | } while (pud++, addr = next, addr != end); |
2507 | return err; |
2508 | } |
2509 | |
2510 | /* |
2511 | * Scan a region of virtual memory, filling in page tables as necessary |
2512 | * and calling a provided function on each leaf page table. |
2513 | */ |
2514 | int apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
2515 | unsigned long size, pte_fn_t fn, void *data) |
2516 | { |
2517 | pgd_t *pgd; |
2518 | unsigned long next; |
2519 | unsigned long end = addr + size; |
2520 | int err; |
2521 | |
2522 | BUG_ON(addr >= end); |
2523 | pgd = pgd_offset(mm, addr); |
2524 | do { |
2525 | next = pgd_addr_end(addr, end); |
2526 | err = apply_to_pud_range(mm, pgd, addr, next, fn, data); |
2527 | if (err) |
2528 | break; |
2529 | } while (pgd++, addr = next, addr != end); |
2530 | |
2531 | return err; |
2532 | } |
2533 | EXPORT_SYMBOL_GPL(apply_to_page_range); |
2534 | |
2535 | /* |
2536 | * handle_pte_fault chooses page fault handler according to an entry |
2537 | * which was read non-atomically. Before making any commitment, on |
2538 | * those architectures or configurations (e.g. i386 with PAE) which |
2539 | * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault |
2540 | * must check under lock before unmapping the pte and proceeding |
2541 | * (but do_wp_page is only called after already making such a check; |
2542 | * and do_anonymous_page can safely check later on). |
2543 | */ |
2544 | static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, |
2545 | pte_t *page_table, pte_t orig_pte) |
2546 | { |
2547 | int same = 1; |
2548 | #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) |
2549 | if (sizeof(pte_t) > sizeof(unsigned long)) { |
2550 | spinlock_t *ptl = pte_lockptr(mm, pmd); |
2551 | spin_lock(ptl); |
2552 | same = pte_same(*page_table, orig_pte); |
2553 | spin_unlock(ptl); |
2554 | } |
2555 | #endif |
2556 | pte_unmap(page_table); |
2557 | return same; |
2558 | } |
2559 | |
2560 | static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) |
2561 | { |
2562 | /* |
2563 | * If the source page was a PFN mapping, we don't have |
2564 | * a "struct page" for it. We do a best-effort copy by |
2565 | * just copying from the original user address. If that |
2566 | * fails, we just zero-fill it. Live with it. |
2567 | */ |
2568 | if (unlikely(!src)) { |
2569 | void *kaddr = kmap_atomic(dst); |
2570 | void __user *uaddr = (void __user *)(va & PAGE_MASK); |
2571 | |
2572 | /* |
2573 | * This really shouldn't fail, because the page is there |
2574 | * in the page tables. But it might just be unreadable, |
2575 | * in which case we just give up and fill the result with |
2576 | * zeroes. |
2577 | */ |
2578 | if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) |
2579 | clear_page(kaddr); |
2580 | kunmap_atomic(kaddr); |
2581 | flush_dcache_page(dst); |
2582 | } else |
2583 | copy_user_highpage(dst, src, va, vma); |
2584 | } |
2585 | |
2586 | /* |
2587 | * This routine handles present pages, when users try to write |
2588 | * to a shared page. It is done by copying the page to a new address |
2589 | * and decrementing the shared-page counter for the old page. |
2590 | * |
2591 | * Note that this routine assumes that the protection checks have been |
2592 | * done by the caller (the low-level page fault routine in most cases). |
2593 | * Thus we can safely just mark it writable once we've done any necessary |
2594 | * COW. |
2595 | * |
2596 | * We also mark the page dirty at this point even though the page will |
2597 | * change only once the write actually happens. This avoids a few races, |
2598 | * and potentially makes it more efficient. |
2599 | * |
2600 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
2601 | * but allow concurrent faults), with pte both mapped and locked. |
2602 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
2603 | */ |
2604 | static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, |
2605 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
2606 | spinlock_t *ptl, pte_t orig_pte) |
2607 | __releases(ptl) |
2608 | { |
2609 | struct page *old_page, *new_page = NULL; |
2610 | pte_t entry; |
2611 | int ret = 0; |
2612 | int page_mkwrite = 0; |
2613 | struct page *dirty_page = NULL; |
2614 | unsigned long mmun_start = 0; /* For mmu_notifiers */ |
2615 | unsigned long mmun_end = 0; /* For mmu_notifiers */ |
2616 | |
2617 | old_page = vm_normal_page(vma, address, orig_pte); |
2618 | if (!old_page) { |
2619 | /* |
2620 | * VM_MIXEDMAP !pfn_valid() case |
2621 | * |
2622 | * We should not cow pages in a shared writeable mapping. |
2623 | * Just mark the pages writable as we can't do any dirty |
2624 | * accounting on raw pfn maps. |
2625 | */ |
2626 | if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
2627 | (VM_WRITE|VM_SHARED)) |
2628 | goto reuse; |
2629 | goto gotten; |
2630 | } |
2631 | |
2632 | /* |
2633 | * Take out anonymous pages first, anonymous shared vmas are |
2634 | * not dirty accountable. |
2635 | */ |
2636 | if (PageAnon(old_page) && !PageKsm(old_page)) { |
2637 | if (!trylock_page(old_page)) { |
2638 | page_cache_get(old_page); |
2639 | pte_unmap_unlock(page_table, ptl); |
2640 | lock_page(old_page); |
2641 | page_table = pte_offset_map_lock(mm, pmd, address, |
2642 | &ptl); |
2643 | if (!pte_same(*page_table, orig_pte)) { |
2644 | unlock_page(old_page); |
2645 | goto unlock; |
2646 | } |
2647 | page_cache_release(old_page); |
2648 | } |
2649 | if (reuse_swap_page(old_page)) { |
2650 | /* |
2651 | * The page is all ours. Move it to our anon_vma so |
2652 | * the rmap code will not search our parent or siblings. |
2653 | * Protected against the rmap code by the page lock. |
2654 | */ |
2655 | page_move_anon_rmap(old_page, vma, address); |
2656 | unlock_page(old_page); |
2657 | goto reuse; |
2658 | } |
2659 | unlock_page(old_page); |
2660 | } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == |
2661 | (VM_WRITE|VM_SHARED))) { |
2662 | /* |
2663 | * Only catch write-faults on shared writable pages, |
2664 | * read-only shared pages can get COWed by |
2665 | * get_user_pages(.write=1, .force=1). |
2666 | */ |
2667 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) { |
2668 | struct vm_fault vmf; |
2669 | int tmp; |
2670 | |
2671 | vmf.virtual_address = (void __user *)(address & |
2672 | PAGE_MASK); |
2673 | vmf.pgoff = old_page->index; |
2674 | vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
2675 | vmf.page = old_page; |
2676 | |
2677 | /* |
2678 | * Notify the address space that the page is about to |
2679 | * become writable so that it can prohibit this or wait |
2680 | * for the page to get into an appropriate state. |
2681 | * |
2682 | * We do this without the lock held, so that it can |
2683 | * sleep if it needs to. |
2684 | */ |
2685 | page_cache_get(old_page); |
2686 | pte_unmap_unlock(page_table, ptl); |
2687 | |
2688 | tmp = vma->vm_ops->page_mkwrite(vma, &vmf); |
2689 | if (unlikely(tmp & |
2690 | (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { |
2691 | ret = tmp; |
2692 | goto unwritable_page; |
2693 | } |
2694 | if (unlikely(!(tmp & VM_FAULT_LOCKED))) { |
2695 | lock_page(old_page); |
2696 | if (!old_page->mapping) { |
2697 | ret = 0; /* retry the fault */ |
2698 | unlock_page(old_page); |
2699 | goto unwritable_page; |
2700 | } |
2701 | } else |
2702 | VM_BUG_ON(!PageLocked(old_page)); |
2703 | |
2704 | /* |
2705 | * Since we dropped the lock we need to revalidate |
2706 | * the PTE as someone else may have changed it. If |
2707 | * they did, we just return, as we can count on the |
2708 | * MMU to tell us if they didn't also make it writable. |
2709 | */ |
2710 | page_table = pte_offset_map_lock(mm, pmd, address, |
2711 | &ptl); |
2712 | if (!pte_same(*page_table, orig_pte)) { |
2713 | unlock_page(old_page); |
2714 | goto unlock; |
2715 | } |
2716 | |
2717 | page_mkwrite = 1; |
2718 | } |
2719 | dirty_page = old_page; |
2720 | get_page(dirty_page); |
2721 | |
2722 | reuse: |
2723 | /* |
2724 | * Clear the pages cpupid information as the existing |
2725 | * information potentially belongs to a now completely |
2726 | * unrelated process. |
2727 | */ |
2728 | if (old_page) |
2729 | page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1); |
2730 | |
2731 | flush_cache_page(vma, address, pte_pfn(orig_pte)); |
2732 | entry = pte_mkyoung(orig_pte); |
2733 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
2734 | if (ptep_set_access_flags(vma, address, page_table, entry,1)) |
2735 | update_mmu_cache(vma, address, page_table); |
2736 | pte_unmap_unlock(page_table, ptl); |
2737 | ret |= VM_FAULT_WRITE; |
2738 | |
2739 | if (!dirty_page) |
2740 | return ret; |
2741 | |
2742 | /* |
2743 | * Yes, Virginia, this is actually required to prevent a race |
2744 | * with clear_page_dirty_for_io() from clearing the page dirty |
2745 | * bit after it clear all dirty ptes, but before a racing |
2746 | * do_wp_page installs a dirty pte. |
2747 | * |
2748 | * __do_fault is protected similarly. |
2749 | */ |
2750 | if (!page_mkwrite) { |
2751 | wait_on_page_locked(dirty_page); |
2752 | set_page_dirty_balance(dirty_page, page_mkwrite); |
2753 | /* file_update_time outside page_lock */ |
2754 | if (vma->vm_file) |
2755 | file_update_time(vma->vm_file); |
2756 | } |
2757 | put_page(dirty_page); |
2758 | if (page_mkwrite) { |
2759 | struct address_space *mapping = dirty_page->mapping; |
2760 | |
2761 | set_page_dirty(dirty_page); |
2762 | unlock_page(dirty_page); |
2763 | page_cache_release(dirty_page); |
2764 | if (mapping) { |
2765 | /* |
2766 | * Some device drivers do not set page.mapping |
2767 | * but still dirty their pages |
2768 | */ |
2769 | balance_dirty_pages_ratelimited(mapping); |
2770 | } |
2771 | } |
2772 | |
2773 | return ret; |
2774 | } |
2775 | |
2776 | /* |
2777 | * Ok, we need to copy. Oh, well.. |
2778 | */ |
2779 | page_cache_get(old_page); |
2780 | gotten: |
2781 | pte_unmap_unlock(page_table, ptl); |
2782 | |
2783 | if (unlikely(anon_vma_prepare(vma))) |
2784 | goto oom; |
2785 | |
2786 | if (is_zero_pfn(pte_pfn(orig_pte))) { |
2787 | new_page = alloc_zeroed_user_highpage_movable(vma, address); |
2788 | if (!new_page) |
2789 | goto oom; |
2790 | } else { |
2791 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); |
2792 | if (!new_page) |
2793 | goto oom; |
2794 | cow_user_page(new_page, old_page, address, vma); |
2795 | } |
2796 | __SetPageUptodate(new_page); |
2797 | |
2798 | if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) |
2799 | goto oom_free_new; |
2800 | |
2801 | mmun_start = address & PAGE_MASK; |
2802 | mmun_end = mmun_start + PAGE_SIZE; |
2803 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
2804 | |
2805 | /* |
2806 | * Re-check the pte - we dropped the lock |
2807 | */ |
2808 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
2809 | if (likely(pte_same(*page_table, orig_pte))) { |
2810 | if (old_page) { |
2811 | if (!PageAnon(old_page)) { |
2812 | dec_mm_counter_fast(mm, MM_FILEPAGES); |
2813 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
2814 | } |
2815 | } else |
2816 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
2817 | flush_cache_page(vma, address, pte_pfn(orig_pte)); |
2818 | entry = mk_pte(new_page, vma->vm_page_prot); |
2819 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
2820 | /* |
2821 | * Clear the pte entry and flush it first, before updating the |
2822 | * pte with the new entry. This will avoid a race condition |
2823 | * seen in the presence of one thread doing SMC and another |
2824 | * thread doing COW. |
2825 | */ |
2826 | ptep_clear_flush(vma, address, page_table); |
2827 | page_add_new_anon_rmap(new_page, vma, address); |
2828 | /* |
2829 | * We call the notify macro here because, when using secondary |
2830 | * mmu page tables (such as kvm shadow page tables), we want the |
2831 | * new page to be mapped directly into the secondary page table. |
2832 | */ |
2833 | set_pte_at_notify(mm, address, page_table, entry); |
2834 | update_mmu_cache(vma, address, page_table); |
2835 | if (old_page) { |
2836 | /* |
2837 | * Only after switching the pte to the new page may |
2838 | * we remove the mapcount here. Otherwise another |
2839 | * process may come and find the rmap count decremented |
2840 | * before the pte is switched to the new page, and |
2841 | * "reuse" the old page writing into it while our pte |
2842 | * here still points into it and can be read by other |
2843 | * threads. |
2844 | * |
2845 | * The critical issue is to order this |
2846 | * page_remove_rmap with the ptp_clear_flush above. |
2847 | * Those stores are ordered by (if nothing else,) |
2848 | * the barrier present in the atomic_add_negative |
2849 | * in page_remove_rmap. |
2850 | * |
2851 | * Then the TLB flush in ptep_clear_flush ensures that |
2852 | * no process can access the old page before the |
2853 | * decremented mapcount is visible. And the old page |
2854 | * cannot be reused until after the decremented |
2855 | * mapcount is visible. So transitively, TLBs to |
2856 | * old page will be flushed before it can be reused. |
2857 | */ |
2858 | page_remove_rmap(old_page); |
2859 | } |
2860 | |
2861 | /* Free the old page.. */ |
2862 | new_page = old_page; |
2863 | ret |= VM_FAULT_WRITE; |
2864 | } else |
2865 | mem_cgroup_uncharge_page(new_page); |
2866 | |
2867 | if (new_page) |
2868 | page_cache_release(new_page); |
2869 | unlock: |
2870 | pte_unmap_unlock(page_table, ptl); |
2871 | if (mmun_end > mmun_start) |
2872 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
2873 | if (old_page) { |
2874 | /* |
2875 | * Don't let another task, with possibly unlocked vma, |
2876 | * keep the mlocked page. |
2877 | */ |
2878 | if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { |
2879 | lock_page(old_page); /* LRU manipulation */ |
2880 | munlock_vma_page(old_page); |
2881 | unlock_page(old_page); |
2882 | } |
2883 | page_cache_release(old_page); |
2884 | } |
2885 | return ret; |
2886 | oom_free_new: |
2887 | page_cache_release(new_page); |
2888 | oom: |
2889 | if (old_page) |
2890 | page_cache_release(old_page); |
2891 | return VM_FAULT_OOM; |
2892 | |
2893 | unwritable_page: |
2894 | page_cache_release(old_page); |
2895 | return ret; |
2896 | } |
2897 | |
2898 | static void unmap_mapping_range_vma(struct vm_area_struct *vma, |
2899 | unsigned long start_addr, unsigned long end_addr, |
2900 | struct zap_details *details) |
2901 | { |
2902 | zap_page_range_single(vma, start_addr, end_addr - start_addr, details); |
2903 | } |
2904 | |
2905 | static inline void unmap_mapping_range_tree(struct rb_root *root, |
2906 | struct zap_details *details) |
2907 | { |
2908 | struct vm_area_struct *vma; |
2909 | pgoff_t vba, vea, zba, zea; |
2910 | |
2911 | vma_interval_tree_foreach(vma, root, |
2912 | details->first_index, details->last_index) { |
2913 | |
2914 | vba = vma->vm_pgoff; |
2915 | vea = vba + vma_pages(vma) - 1; |
2916 | /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ |
2917 | zba = details->first_index; |
2918 | if (zba < vba) |
2919 | zba = vba; |
2920 | zea = details->last_index; |
2921 | if (zea > vea) |
2922 | zea = vea; |
2923 | |
2924 | unmap_mapping_range_vma(vma, |
2925 | ((zba - vba) << PAGE_SHIFT) + vma->vm_start, |
2926 | ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, |
2927 | details); |
2928 | } |
2929 | } |
2930 | |
2931 | static inline void unmap_mapping_range_list(struct list_head *head, |
2932 | struct zap_details *details) |
2933 | { |
2934 | struct vm_area_struct *vma; |
2935 | |
2936 | /* |
2937 | * In nonlinear VMAs there is no correspondence between virtual address |
2938 | * offset and file offset. So we must perform an exhaustive search |
2939 | * across *all* the pages in each nonlinear VMA, not just the pages |
2940 | * whose virtual address lies outside the file truncation point. |
2941 | */ |
2942 | list_for_each_entry(vma, head, shared.nonlinear) { |
2943 | details->nonlinear_vma = vma; |
2944 | unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); |
2945 | } |
2946 | } |
2947 | |
2948 | /** |
2949 | * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. |
2950 | * @mapping: the address space containing mmaps to be unmapped. |
2951 | * @holebegin: byte in first page to unmap, relative to the start of |
2952 | * the underlying file. This will be rounded down to a PAGE_SIZE |
2953 | * boundary. Note that this is different from truncate_pagecache(), which |
2954 | * must keep the partial page. In contrast, we must get rid of |
2955 | * partial pages. |
2956 | * @holelen: size of prospective hole in bytes. This will be rounded |
2957 | * up to a PAGE_SIZE boundary. A holelen of zero truncates to the |
2958 | * end of the file. |
2959 | * @even_cows: 1 when truncating a file, unmap even private COWed pages; |
2960 | * but 0 when invalidating pagecache, don't throw away private data. |
2961 | */ |
2962 | void unmap_mapping_range(struct address_space *mapping, |
2963 | loff_t const holebegin, loff_t const holelen, int even_cows) |
2964 | { |
2965 | struct zap_details details; |
2966 | pgoff_t hba = holebegin >> PAGE_SHIFT; |
2967 | pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
2968 | |
2969 | /* Check for overflow. */ |
2970 | if (sizeof(holelen) > sizeof(hlen)) { |
2971 | long long holeend = |
2972 | (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
2973 | if (holeend & ~(long long)ULONG_MAX) |
2974 | hlen = ULONG_MAX - hba + 1; |
2975 | } |
2976 | |
2977 | details.check_mapping = even_cows? NULL: mapping; |
2978 | details.nonlinear_vma = NULL; |
2979 | details.first_index = hba; |
2980 | details.last_index = hba + hlen - 1; |
2981 | if (details.last_index < details.first_index) |
2982 | details.last_index = ULONG_MAX; |
2983 | |
2984 | |
2985 | mutex_lock(&mapping->i_mmap_mutex); |
2986 | if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) |
2987 | unmap_mapping_range_tree(&mapping->i_mmap, &details); |
2988 | if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) |
2989 | unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); |
2990 | mutex_unlock(&mapping->i_mmap_mutex); |
2991 | } |
2992 | EXPORT_SYMBOL(unmap_mapping_range); |
2993 | |
2994 | /* |
2995 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
2996 | * but allow concurrent faults), and pte mapped but not yet locked. |
2997 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
2998 | */ |
2999 | static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, |
3000 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
3001 | unsigned int flags, pte_t orig_pte) |
3002 | { |
3003 | spinlock_t *ptl; |
3004 | struct page *page, *swapcache; |
3005 | swp_entry_t entry; |
3006 | pte_t pte; |
3007 | int locked; |
3008 | struct mem_cgroup *ptr; |
3009 | int exclusive = 0; |
3010 | int ret = 0; |
3011 | |
3012 | if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) |
3013 | goto out; |
3014 | |
3015 | entry = pte_to_swp_entry(orig_pte); |
3016 | if (unlikely(non_swap_entry(entry))) { |
3017 | if (is_migration_entry(entry)) { |
3018 | migration_entry_wait(mm, pmd, address); |
3019 | } else if (is_hwpoison_entry(entry)) { |
3020 | ret = VM_FAULT_HWPOISON; |
3021 | } else { |
3022 | print_bad_pte(vma, address, orig_pte, NULL); |
3023 | ret = VM_FAULT_SIGBUS; |
3024 | } |
3025 | goto out; |
3026 | } |
3027 | delayacct_set_flag(DELAYACCT_PF_SWAPIN); |
3028 | page = lookup_swap_cache(entry); |
3029 | if (!page) { |
3030 | page = swapin_readahead(entry, |
3031 | GFP_HIGHUSER_MOVABLE, vma, address); |
3032 | if (!page) { |
3033 | /* |
3034 | * Back out if somebody else faulted in this pte |
3035 | * while we released the pte lock. |
3036 | */ |
3037 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
3038 | if (likely(pte_same(*page_table, orig_pte))) |
3039 | ret = VM_FAULT_OOM; |
3040 | delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
3041 | goto unlock; |
3042 | } |
3043 | |
3044 | /* Had to read the page from swap area: Major fault */ |
3045 | ret = VM_FAULT_MAJOR; |
3046 | count_vm_event(PGMAJFAULT); |
3047 | mem_cgroup_count_vm_event(mm, PGMAJFAULT); |
3048 | } else if (PageHWPoison(page)) { |
3049 | /* |
3050 | * hwpoisoned dirty swapcache pages are kept for killing |
3051 | * owner processes (which may be unknown at hwpoison time) |
3052 | */ |
3053 | ret = VM_FAULT_HWPOISON; |
3054 | delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
3055 | swapcache = page; |
3056 | goto out_release; |
3057 | } |
3058 | |
3059 | swapcache = page; |
3060 | locked = lock_page_or_retry(page, mm, flags); |
3061 | |
3062 | delayacct_clear_flag(DELAYACCT_PF_SWAPIN); |
3063 | if (!locked) { |
3064 | ret |= VM_FAULT_RETRY; |
3065 | goto out_release; |
3066 | } |
3067 | |
3068 | /* |
3069 | * Make sure try_to_free_swap or reuse_swap_page or swapoff did not |
3070 | * release the swapcache from under us. The page pin, and pte_same |
3071 | * test below, are not enough to exclude that. Even if it is still |
3072 | * swapcache, we need to check that the page's swap has not changed. |
3073 | */ |
3074 | if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) |
3075 | goto out_page; |
3076 | |
3077 | page = ksm_might_need_to_copy(page, vma, address); |
3078 | if (unlikely(!page)) { |
3079 | ret = VM_FAULT_OOM; |
3080 | page = swapcache; |
3081 | goto out_page; |
3082 | } |
3083 | |
3084 | if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { |
3085 | ret = VM_FAULT_OOM; |
3086 | goto out_page; |
3087 | } |
3088 | |
3089 | /* |
3090 | * Back out if somebody else already faulted in this pte. |
3091 | */ |
3092 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
3093 | if (unlikely(!pte_same(*page_table, orig_pte))) |
3094 | goto out_nomap; |
3095 | |
3096 | if (unlikely(!PageUptodate(page))) { |
3097 | ret = VM_FAULT_SIGBUS; |
3098 | goto out_nomap; |
3099 | } |
3100 | |
3101 | /* |
3102 | * The page isn't present yet, go ahead with the fault. |
3103 | * |
3104 | * Be careful about the sequence of operations here. |
3105 | * To get its accounting right, reuse_swap_page() must be called |
3106 | * while the page is counted on swap but not yet in mapcount i.e. |
3107 | * before page_add_anon_rmap() and swap_free(); try_to_free_swap() |
3108 | * must be called after the swap_free(), or it will never succeed. |
3109 | * Because delete_from_swap_page() may be called by reuse_swap_page(), |
3110 | * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry |
3111 | * in page->private. In this case, a record in swap_cgroup is silently |
3112 | * discarded at swap_free(). |
3113 | */ |
3114 | |
3115 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
3116 | dec_mm_counter_fast(mm, MM_SWAPENTS); |
3117 | pte = mk_pte(page, vma->vm_page_prot); |
3118 | if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { |
3119 | pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
3120 | flags &= ~FAULT_FLAG_WRITE; |
3121 | ret |= VM_FAULT_WRITE; |
3122 | exclusive = 1; |
3123 | } |
3124 | flush_icache_page(vma, page); |
3125 | if (pte_swp_soft_dirty(orig_pte)) |
3126 | pte = pte_mksoft_dirty(pte); |
3127 | set_pte_at(mm, address, page_table, pte); |
3128 | if (page == swapcache) |
3129 | do_page_add_anon_rmap(page, vma, address, exclusive); |
3130 | else /* ksm created a completely new copy */ |
3131 | page_add_new_anon_rmap(page, vma, address); |
3132 | /* It's better to call commit-charge after rmap is established */ |
3133 | mem_cgroup_commit_charge_swapin(page, ptr); |
3134 | |
3135 | swap_free(entry); |
3136 | if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) |
3137 | try_to_free_swap(page); |
3138 | unlock_page(page); |
3139 | if (page != swapcache) { |
3140 | /* |
3141 | * Hold the lock to avoid the swap entry to be reused |
3142 | * until we take the PT lock for the pte_same() check |
3143 | * (to avoid false positives from pte_same). For |
3144 | * further safety release the lock after the swap_free |
3145 | * so that the swap count won't change under a |
3146 | * parallel locked swapcache. |
3147 | */ |
3148 | unlock_page(swapcache); |
3149 | page_cache_release(swapcache); |
3150 | } |
3151 | |
3152 | if (flags & FAULT_FLAG_WRITE) { |
3153 | ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); |
3154 | if (ret & VM_FAULT_ERROR) |
3155 | ret &= VM_FAULT_ERROR; |
3156 | goto out; |
3157 | } |
3158 | |
3159 | /* No need to invalidate - it was non-present before */ |
3160 | update_mmu_cache(vma, address, page_table); |
3161 | unlock: |
3162 | pte_unmap_unlock(page_table, ptl); |
3163 | out: |
3164 | return ret; |
3165 | out_nomap: |
3166 | mem_cgroup_cancel_charge_swapin(ptr); |
3167 | pte_unmap_unlock(page_table, ptl); |
3168 | out_page: |
3169 | unlock_page(page); |
3170 | out_release: |
3171 | page_cache_release(page); |
3172 | if (page != swapcache) { |
3173 | unlock_page(swapcache); |
3174 | page_cache_release(swapcache); |
3175 | } |
3176 | return ret; |
3177 | } |
3178 | |
3179 | /* |
3180 | * This is like a special single-page "expand_{down|up}wards()", |
3181 | * except we must first make sure that 'address{-|+}PAGE_SIZE' |
3182 | * doesn't hit another vma. |
3183 | */ |
3184 | static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) |
3185 | { |
3186 | address &= PAGE_MASK; |
3187 | if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { |
3188 | struct vm_area_struct *prev = vma->vm_prev; |
3189 | |
3190 | /* |
3191 | * Is there a mapping abutting this one below? |
3192 | * |
3193 | * That's only ok if it's the same stack mapping |
3194 | * that has gotten split.. |
3195 | */ |
3196 | if (prev && prev->vm_end == address) |
3197 | return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; |
3198 | |
3199 | expand_downwards(vma, address - PAGE_SIZE); |
3200 | } |
3201 | if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { |
3202 | struct vm_area_struct *next = vma->vm_next; |
3203 | |
3204 | /* As VM_GROWSDOWN but s/below/above/ */ |
3205 | if (next && next->vm_start == address + PAGE_SIZE) |
3206 | return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; |
3207 | |
3208 | expand_upwards(vma, address + PAGE_SIZE); |
3209 | } |
3210 | return 0; |
3211 | } |
3212 | |
3213 | /* |
3214 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
3215 | * but allow concurrent faults), and pte mapped but not yet locked. |
3216 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
3217 | */ |
3218 | static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
3219 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
3220 | unsigned int flags) |
3221 | { |
3222 | struct page *page; |
3223 | spinlock_t *ptl; |
3224 | pte_t entry; |
3225 | |
3226 | pte_unmap(page_table); |
3227 | |
3228 | /* Check if we need to add a guard page to the stack */ |
3229 | if (check_stack_guard_page(vma, address) < 0) |
3230 | return VM_FAULT_SIGBUS; |
3231 | |
3232 | /* Use the zero-page for reads */ |
3233 | if (!(flags & FAULT_FLAG_WRITE)) { |
3234 | entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), |
3235 | vma->vm_page_prot)); |
3236 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
3237 | if (!pte_none(*page_table)) |
3238 | goto unlock; |
3239 | goto setpte; |
3240 | } |
3241 | |
3242 | /* Allocate our own private page. */ |
3243 | if (unlikely(anon_vma_prepare(vma))) |
3244 | goto oom; |
3245 | page = alloc_zeroed_user_highpage_movable(vma, address); |
3246 | if (!page) |
3247 | goto oom; |
3248 | /* |
3249 | * The memory barrier inside __SetPageUptodate makes sure that |
3250 | * preceeding stores to the page contents become visible before |
3251 | * the set_pte_at() write. |
3252 | */ |
3253 | __SetPageUptodate(page); |
3254 | |
3255 | if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) |
3256 | goto oom_free_page; |
3257 | |
3258 | entry = mk_pte(page, vma->vm_page_prot); |
3259 | if (vma->vm_flags & VM_WRITE) |
3260 | entry = pte_mkwrite(pte_mkdirty(entry)); |
3261 | |
3262 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
3263 | if (!pte_none(*page_table)) |
3264 | goto release; |
3265 | |
3266 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
3267 | page_add_new_anon_rmap(page, vma, address); |
3268 | setpte: |
3269 | set_pte_at(mm, address, page_table, entry); |
3270 | |
3271 | /* No need to invalidate - it was non-present before */ |
3272 | update_mmu_cache(vma, address, page_table); |
3273 | unlock: |
3274 | pte_unmap_unlock(page_table, ptl); |
3275 | return 0; |
3276 | release: |
3277 | mem_cgroup_uncharge_page(page); |
3278 | page_cache_release(page); |
3279 | goto unlock; |
3280 | oom_free_page: |
3281 | page_cache_release(page); |
3282 | oom: |
3283 | return VM_FAULT_OOM; |
3284 | } |
3285 | |
3286 | /* |
3287 | * __do_fault() tries to create a new page mapping. It aggressively |
3288 | * tries to share with existing pages, but makes a separate copy if |
3289 | * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid |
3290 | * the next page fault. |
3291 | * |
3292 | * As this is called only for pages that do not currently exist, we |
3293 | * do not need to flush old virtual caches or the TLB. |
3294 | * |
3295 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
3296 | * but allow concurrent faults), and pte neither mapped nor locked. |
3297 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
3298 | */ |
3299 | static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
3300 | unsigned long address, pmd_t *pmd, |
3301 | pgoff_t pgoff, unsigned int flags, pte_t orig_pte) |
3302 | { |
3303 | pte_t *page_table; |
3304 | spinlock_t *ptl; |
3305 | struct page *page; |
3306 | struct page *cow_page; |
3307 | pte_t entry; |
3308 | int anon = 0; |
3309 | struct page *dirty_page = NULL; |
3310 | struct vm_fault vmf; |
3311 | int ret; |
3312 | int page_mkwrite = 0; |
3313 | |
3314 | /* |
3315 | * If we do COW later, allocate page befor taking lock_page() |
3316 | * on the file cache page. This will reduce lock holding time. |
3317 | */ |
3318 | if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { |
3319 | |
3320 | if (unlikely(anon_vma_prepare(vma))) |
3321 | return VM_FAULT_OOM; |
3322 | |
3323 | cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); |
3324 | if (!cow_page) |
3325 | return VM_FAULT_OOM; |
3326 | |
3327 | if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) { |
3328 | page_cache_release(cow_page); |
3329 | return VM_FAULT_OOM; |
3330 | } |
3331 | } else |
3332 | cow_page = NULL; |
3333 | |
3334 | vmf.virtual_address = (void __user *)(address & PAGE_MASK); |
3335 | vmf.pgoff = pgoff; |
3336 | vmf.flags = flags; |
3337 | vmf.page = NULL; |
3338 | |
3339 | ret = vma->vm_ops->fault(vma, &vmf); |
3340 | if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | |
3341 | VM_FAULT_RETRY))) |
3342 | goto uncharge_out; |
3343 | |
3344 | if (unlikely(PageHWPoison(vmf.page))) { |
3345 | if (ret & VM_FAULT_LOCKED) |
3346 | unlock_page(vmf.page); |
3347 | ret = VM_FAULT_HWPOISON; |
3348 | goto uncharge_out; |
3349 | } |
3350 | |
3351 | /* |
3352 | * For consistency in subsequent calls, make the faulted page always |
3353 | * locked. |
3354 | */ |
3355 | if (unlikely(!(ret & VM_FAULT_LOCKED))) |
3356 | lock_page(vmf.page); |
3357 | else |
3358 | VM_BUG_ON(!PageLocked(vmf.page)); |
3359 | |
3360 | /* |
3361 | * Should we do an early C-O-W break? |
3362 | */ |
3363 | page = vmf.page; |
3364 | if (flags & FAULT_FLAG_WRITE) { |
3365 | if (!(vma->vm_flags & VM_SHARED)) { |
3366 | page = cow_page; |
3367 | anon = 1; |
3368 | copy_user_highpage(page, vmf.page, address, vma); |
3369 | __SetPageUptodate(page); |
3370 | } else { |
3371 | /* |
3372 | * If the page will be shareable, see if the backing |
3373 | * address space wants to know that the page is about |
3374 | * to become writable |
3375 | */ |
3376 | if (vma->vm_ops->page_mkwrite) { |
3377 | int tmp; |
3378 | |
3379 | unlock_page(page); |
3380 | vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
3381 | tmp = vma->vm_ops->page_mkwrite(vma, &vmf); |
3382 | if (unlikely(tmp & |
3383 | (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { |
3384 | ret = tmp; |
3385 | goto unwritable_page; |
3386 | } |
3387 | if (unlikely(!(tmp & VM_FAULT_LOCKED))) { |
3388 | lock_page(page); |
3389 | if (!page->mapping) { |
3390 | ret = 0; /* retry the fault */ |
3391 | unlock_page(page); |
3392 | goto unwritable_page; |
3393 | } |
3394 | } else |
3395 | VM_BUG_ON(!PageLocked(page)); |
3396 | page_mkwrite = 1; |
3397 | } |
3398 | } |
3399 | |
3400 | } |
3401 | |
3402 | page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |
3403 | |
3404 | /* |
3405 | * This silly early PAGE_DIRTY setting removes a race |
3406 | * due to the bad i386 page protection. But it's valid |
3407 | * for other architectures too. |
3408 | * |
3409 | * Note that if FAULT_FLAG_WRITE is set, we either now have |
3410 | * an exclusive copy of the page, or this is a shared mapping, |
3411 | * so we can make it writable and dirty to avoid having to |
3412 | * handle that later. |
3413 | */ |
3414 | /* Only go through if we didn't race with anybody else... */ |
3415 | if (likely(pte_same(*page_table, orig_pte))) { |
3416 | flush_icache_page(vma, page); |
3417 | entry = mk_pte(page, vma->vm_page_prot); |
3418 | if (flags & FAULT_FLAG_WRITE) |
3419 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
3420 | else if (pte_file(orig_pte) && pte_file_soft_dirty(orig_pte)) |
3421 | pte_mksoft_dirty(entry); |
3422 | if (anon) { |
3423 | inc_mm_counter_fast(mm, MM_ANONPAGES); |
3424 | page_add_new_anon_rmap(page, vma, address); |
3425 | } else { |
3426 | inc_mm_counter_fast(mm, MM_FILEPAGES); |
3427 | page_add_file_rmap(page); |
3428 | if (flags & FAULT_FLAG_WRITE) { |
3429 | dirty_page = page; |
3430 | get_page(dirty_page); |
3431 | } |
3432 | } |
3433 | set_pte_at(mm, address, page_table, entry); |
3434 | |
3435 | /* no need to invalidate: a not-present page won't be cached */ |
3436 | update_mmu_cache(vma, address, page_table); |
3437 | } else { |
3438 | if (cow_page) |
3439 | mem_cgroup_uncharge_page(cow_page); |
3440 | if (anon) |
3441 | page_cache_release(page); |
3442 | else |
3443 | anon = 1; /* no anon but release faulted_page */ |
3444 | } |
3445 | |
3446 | pte_unmap_unlock(page_table, ptl); |
3447 | |
3448 | if (dirty_page) { |
3449 | struct address_space *mapping = page->mapping; |
3450 | int dirtied = 0; |
3451 | |
3452 | if (set_page_dirty(dirty_page)) |
3453 | dirtied = 1; |
3454 | unlock_page(dirty_page); |
3455 | put_page(dirty_page); |
3456 | if ((dirtied || page_mkwrite) && mapping) { |
3457 | /* |
3458 | * Some device drivers do not set page.mapping but still |
3459 | * dirty their pages |
3460 | */ |
3461 | balance_dirty_pages_ratelimited(mapping); |
3462 | } |
3463 | |
3464 | /* file_update_time outside page_lock */ |
3465 | if (vma->vm_file && !page_mkwrite) |
3466 | file_update_time(vma->vm_file); |
3467 | } else { |
3468 | unlock_page(vmf.page); |
3469 | if (anon) |
3470 | page_cache_release(vmf.page); |
3471 | } |
3472 | |
3473 | return ret; |
3474 | |
3475 | unwritable_page: |
3476 | page_cache_release(page); |
3477 | return ret; |
3478 | uncharge_out: |
3479 | /* fs's fault handler get error */ |
3480 | if (cow_page) { |
3481 | mem_cgroup_uncharge_page(cow_page); |
3482 | page_cache_release(cow_page); |
3483 | } |
3484 | return ret; |
3485 | } |
3486 | |
3487 | static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
3488 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
3489 | unsigned int flags, pte_t orig_pte) |
3490 | { |
3491 | pgoff_t pgoff = (((address & PAGE_MASK) |
3492 | - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
3493 | |
3494 | pte_unmap(page_table); |
3495 | return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); |
3496 | } |
3497 | |
3498 | /* |
3499 | * Fault of a previously existing named mapping. Repopulate the pte |
3500 | * from the encoded file_pte if possible. This enables swappable |
3501 | * nonlinear vmas. |
3502 | * |
3503 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
3504 | * but allow concurrent faults), and pte mapped but not yet locked. |
3505 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
3506 | */ |
3507 | static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
3508 | unsigned long address, pte_t *page_table, pmd_t *pmd, |
3509 | unsigned int flags, pte_t orig_pte) |
3510 | { |
3511 | pgoff_t pgoff; |
3512 | |
3513 | flags |= FAULT_FLAG_NONLINEAR; |
3514 | |
3515 | if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) |
3516 | return 0; |
3517 | |
3518 | if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { |
3519 | /* |
3520 | * Page table corrupted: show pte and kill process. |
3521 | */ |
3522 | print_bad_pte(vma, address, orig_pte, NULL); |
3523 | return VM_FAULT_SIGBUS; |
3524 | } |
3525 | |
3526 | pgoff = pte_to_pgoff(orig_pte); |
3527 | return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); |
3528 | } |
3529 | |
3530 | int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, |
3531 | unsigned long addr, int page_nid, |
3532 | int *flags) |
3533 | { |
3534 | get_page(page); |
3535 | |
3536 | count_vm_numa_event(NUMA_HINT_FAULTS); |
3537 | if (page_nid == numa_node_id()) { |
3538 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
3539 | *flags |= TNF_FAULT_LOCAL; |
3540 | } |
3541 | |
3542 | return mpol_misplaced(page, vma, addr); |
3543 | } |
3544 | |
3545 | int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, |
3546 | unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd) |
3547 | { |
3548 | struct page *page = NULL; |
3549 | spinlock_t *ptl; |
3550 | int page_nid = -1; |
3551 | int last_cpupid; |
3552 | int target_nid; |
3553 | bool migrated = false; |
3554 | int flags = 0; |
3555 | |
3556 | /* |
3557 | * The "pte" at this point cannot be used safely without |
3558 | * validation through pte_unmap_same(). It's of NUMA type but |
3559 | * the pfn may be screwed if the read is non atomic. |
3560 | * |
3561 | * ptep_modify_prot_start is not called as this is clearing |
3562 | * the _PAGE_NUMA bit and it is not really expected that there |
3563 | * would be concurrent hardware modifications to the PTE. |
3564 | */ |
3565 | ptl = pte_lockptr(mm, pmd); |
3566 | spin_lock(ptl); |
3567 | if (unlikely(!pte_same(*ptep, pte))) { |
3568 | pte_unmap_unlock(ptep, ptl); |
3569 | goto out; |
3570 | } |
3571 | |
3572 | pte = pte_mknonnuma(pte); |
3573 | set_pte_at(mm, addr, ptep, pte); |
3574 | update_mmu_cache(vma, addr, ptep); |
3575 | |
3576 | page = vm_normal_page(vma, addr, pte); |
3577 | if (!page) { |
3578 | pte_unmap_unlock(ptep, ptl); |
3579 | return 0; |
3580 | } |
3581 | BUG_ON(is_zero_pfn(page_to_pfn(page))); |
3582 | |
3583 | /* |
3584 | * Avoid grouping on DSO/COW pages in specific and RO pages |
3585 | * in general, RO pages shouldn't hurt as much anyway since |
3586 | * they can be in shared cache state. |
3587 | */ |
3588 | if (!pte_write(pte)) |
3589 | flags |= TNF_NO_GROUP; |
3590 | |
3591 | /* |
3592 | * Flag if the page is shared between multiple address spaces. This |
3593 | * is later used when determining whether to group tasks together |
3594 | */ |
3595 | if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) |
3596 | flags |= TNF_SHARED; |
3597 | |
3598 | last_cpupid = page_cpupid_last(page); |
3599 | page_nid = page_to_nid(page); |
3600 | target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags); |
3601 | pte_unmap_unlock(ptep, ptl); |
3602 | if (target_nid == -1) { |
3603 | put_page(page); |
3604 | goto out; |
3605 | } |
3606 | |
3607 | /* Migrate to the requested node */ |
3608 | migrated = migrate_misplaced_page(page, vma, target_nid); |
3609 | if (migrated) { |
3610 | page_nid = target_nid; |
3611 | flags |= TNF_MIGRATED; |
3612 | } |
3613 | |
3614 | out: |
3615 | if (page_nid != -1) |
3616 | task_numa_fault(last_cpupid, page_nid, 1, flags); |
3617 | return 0; |
3618 | } |
3619 | |
3620 | /* |
3621 | * These routines also need to handle stuff like marking pages dirty |
3622 | * and/or accessed for architectures that don't do it in hardware (most |
3623 | * RISC architectures). The early dirtying is also good on the i386. |
3624 | * |
3625 | * There is also a hook called "update_mmu_cache()" that architectures |
3626 | * with external mmu caches can use to update those (ie the Sparc or |
3627 | * PowerPC hashed page tables that act as extended TLBs). |
3628 | * |
3629 | * We enter with non-exclusive mmap_sem (to exclude vma changes, |
3630 | * but allow concurrent faults), and pte mapped but not yet locked. |
3631 | * We return with mmap_sem still held, but pte unmapped and unlocked. |
3632 | */ |
3633 | static int handle_pte_fault(struct mm_struct *mm, |
3634 | struct vm_area_struct *vma, unsigned long address, |
3635 | pte_t *pte, pmd_t *pmd, unsigned int flags) |
3636 | { |
3637 | pte_t entry; |
3638 | spinlock_t *ptl; |
3639 | |
3640 | entry = *pte; |
3641 | if (!pte_present(entry)) { |
3642 | if (pte_none(entry)) { |
3643 | if (vma->vm_ops) { |
3644 | if (likely(vma->vm_ops->fault)) |
3645 | return do_linear_fault(mm, vma, address, |
3646 | pte, pmd, flags, entry); |
3647 | } |
3648 | return do_anonymous_page(mm, vma, address, |
3649 | pte, pmd, flags); |
3650 | } |
3651 | if (pte_file(entry)) |
3652 | return do_nonlinear_fault(mm, vma, address, |
3653 | pte, pmd, flags, entry); |
3654 | return do_swap_page(mm, vma, address, |
3655 | pte, pmd, flags, entry); |
3656 | } |
3657 | |
3658 | if (pte_numa(entry)) |
3659 | return do_numa_page(mm, vma, address, entry, pte, pmd); |
3660 | |
3661 | ptl = pte_lockptr(mm, pmd); |
3662 | spin_lock(ptl); |
3663 | if (unlikely(!pte_same(*pte, entry))) |
3664 | goto unlock; |
3665 | if (flags & FAULT_FLAG_WRITE) { |
3666 | if (!pte_write(entry)) |
3667 | return do_wp_page(mm, vma, address, |
3668 | pte, pmd, ptl, entry); |
3669 | entry = pte_mkdirty(entry); |
3670 | } |
3671 | entry = pte_mkyoung(entry); |
3672 | if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { |
3673 | update_mmu_cache(vma, address, pte); |
3674 | } else { |
3675 | /* |
3676 | * This is needed only for protection faults but the arch code |
3677 | * is not yet telling us if this is a protection fault or not. |
3678 | * This still avoids useless tlb flushes for .text page faults |
3679 | * with threads. |
3680 | */ |
3681 | if (flags & FAULT_FLAG_WRITE) |
3682 | flush_tlb_fix_spurious_fault(vma, address); |
3683 | } |
3684 | unlock: |
3685 | pte_unmap_unlock(pte, ptl); |
3686 | return 0; |
3687 | } |
3688 | |
3689 | /* |
3690 | * By the time we get here, we already hold the mm semaphore |
3691 | */ |
3692 | static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
3693 | unsigned long address, unsigned int flags) |
3694 | { |
3695 | pgd_t *pgd; |
3696 | pud_t *pud; |
3697 | pmd_t *pmd; |
3698 | pte_t *pte; |
3699 | |
3700 | if (unlikely(is_vm_hugetlb_page(vma))) |
3701 | return hugetlb_fault(mm, vma, address, flags); |
3702 | |
3703 | retry: |
3704 | pgd = pgd_offset(mm, address); |
3705 | pud = pud_alloc(mm, pgd, address); |
3706 | if (!pud) |
3707 | return VM_FAULT_OOM; |
3708 | pmd = pmd_alloc(mm, pud, address); |
3709 | if (!pmd) |
3710 | return VM_FAULT_OOM; |
3711 | if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { |
3712 | int ret = VM_FAULT_FALLBACK; |
3713 | if (!vma->vm_ops) |
3714 | ret = do_huge_pmd_anonymous_page(mm, vma, address, |
3715 | pmd, flags); |
3716 | if (!(ret & VM_FAULT_FALLBACK)) |
3717 | return ret; |
3718 | } else { |
3719 | pmd_t orig_pmd = *pmd; |
3720 | int ret; |
3721 | |
3722 | barrier(); |
3723 | if (pmd_trans_huge(orig_pmd)) { |
3724 | unsigned int dirty = flags & FAULT_FLAG_WRITE; |
3725 | |
3726 | /* |
3727 | * If the pmd is splitting, return and retry the |
3728 | * the fault. Alternative: wait until the split |
3729 | * is done, and goto retry. |
3730 | */ |
3731 | if (pmd_trans_splitting(orig_pmd)) |
3732 | return 0; |
3733 | |
3734 | if (pmd_numa(orig_pmd)) |
3735 | return do_huge_pmd_numa_page(mm, vma, address, |
3736 | orig_pmd, pmd); |
3737 | |
3738 | if (dirty && !pmd_write(orig_pmd)) { |
3739 | ret = do_huge_pmd_wp_page(mm, vma, address, pmd, |
3740 | orig_pmd); |
3741 | /* |
3742 | * If COW results in an oom, the huge pmd will |
3743 | * have been split, so retry the fault on the |
3744 | * pte for a smaller charge. |
3745 | */ |
3746 | if (unlikely(ret & VM_FAULT_OOM)) |
3747 | goto retry; |
3748 | return ret; |
3749 | } else { |
3750 | huge_pmd_set_accessed(mm, vma, address, pmd, |
3751 | orig_pmd, dirty); |
3752 | } |
3753 | |
3754 | return 0; |
3755 | } |
3756 | } |
3757 | |
3758 | /* THP should already have been handled */ |
3759 | BUG_ON(pmd_numa(*pmd)); |
3760 | |
3761 | /* |
3762 | * Use __pte_alloc instead of pte_alloc_map, because we can't |
3763 | * run pte_offset_map on the pmd, if an huge pmd could |
3764 | * materialize from under us from a different thread. |
3765 | */ |
3766 | if (unlikely(pmd_none(*pmd)) && |
3767 | unlikely(__pte_alloc(mm, vma, pmd, address))) |
3768 | return VM_FAULT_OOM; |
3769 | /* if an huge pmd materialized from under us just retry later */ |
3770 | if (unlikely(pmd_trans_huge(*pmd))) |
3771 | return 0; |
3772 | /* |
3773 | * A regular pmd is established and it can't morph into a huge pmd |
3774 | * from under us anymore at this point because we hold the mmap_sem |
3775 | * read mode and khugepaged takes it in write mode. So now it's |
3776 | * safe to run pte_offset_map(). |
3777 | */ |
3778 | pte = pte_offset_map(pmd, address); |
3779 | |
3780 | return handle_pte_fault(mm, vma, address, pte, pmd, flags); |
3781 | } |
3782 | |
3783 | int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
3784 | unsigned long address, unsigned int flags) |
3785 | { |
3786 | int ret; |
3787 | |
3788 | __set_current_state(TASK_RUNNING); |
3789 | |
3790 | count_vm_event(PGFAULT); |
3791 | mem_cgroup_count_vm_event(mm, PGFAULT); |
3792 | |
3793 | /* do counter updates before entering really critical section. */ |
3794 | check_sync_rss_stat(current); |
3795 | |
3796 | /* |
3797 | * Enable the memcg OOM handling for faults triggered in user |
3798 | * space. Kernel faults are handled more gracefully. |
3799 | */ |
3800 | if (flags & FAULT_FLAG_USER) |
3801 | mem_cgroup_oom_enable(); |
3802 | |
3803 | ret = __handle_mm_fault(mm, vma, address, flags); |
3804 | |
3805 | if (flags & FAULT_FLAG_USER) { |
3806 | mem_cgroup_oom_disable(); |
3807 | /* |
3808 | * The task may have entered a memcg OOM situation but |
3809 | * if the allocation error was handled gracefully (no |
3810 | * VM_FAULT_OOM), there is no need to kill anything. |
3811 | * Just clean up the OOM state peacefully. |
3812 | */ |
3813 | if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) |
3814 | mem_cgroup_oom_synchronize(false); |
3815 | } |
3816 | |
3817 | return ret; |
3818 | } |
3819 | |
3820 | #ifndef __PAGETABLE_PUD_FOLDED |
3821 | /* |
3822 | * Allocate page upper directory. |
3823 | * We've already handled the fast-path in-line. |
3824 | */ |
3825 | int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) |
3826 | { |
3827 | pud_t *new = pud_alloc_one(mm, address); |
3828 | if (!new) |
3829 | return -ENOMEM; |
3830 | |
3831 | smp_wmb(); /* See comment in __pte_alloc */ |
3832 | |
3833 | spin_lock(&mm->page_table_lock); |
3834 | if (pgd_present(*pgd)) /* Another has populated it */ |
3835 | pud_free(mm, new); |
3836 | else |
3837 | pgd_populate(mm, pgd, new); |
3838 | spin_unlock(&mm->page_table_lock); |
3839 | return 0; |
3840 | } |
3841 | #endif /* __PAGETABLE_PUD_FOLDED */ |
3842 | |
3843 | #ifndef __PAGETABLE_PMD_FOLDED |
3844 | /* |
3845 | * Allocate page middle directory. |
3846 | * We've already handled the fast-path in-line. |
3847 | */ |
3848 | int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) |
3849 | { |
3850 | pmd_t *new = pmd_alloc_one(mm, address); |
3851 | if (!new) |
3852 | return -ENOMEM; |
3853 | |
3854 | smp_wmb(); /* See comment in __pte_alloc */ |
3855 | |
3856 | spin_lock(&mm->page_table_lock); |
3857 | #ifndef __ARCH_HAS_4LEVEL_HACK |
3858 | if (pud_present(*pud)) /* Another has populated it */ |
3859 | pmd_free(mm, new); |
3860 | else |
3861 | pud_populate(mm, pud, new); |
3862 | #else |
3863 | if (pgd_present(*pud)) /* Another has populated it */ |
3864 | pmd_free(mm, new); |
3865 | else |
3866 | pgd_populate(mm, pud, new); |
3867 | #endif /* __ARCH_HAS_4LEVEL_HACK */ |
3868 | spin_unlock(&mm->page_table_lock); |
3869 | return 0; |
3870 | } |
3871 | #endif /* __PAGETABLE_PMD_FOLDED */ |
3872 | |
3873 | #if !defined(__HAVE_ARCH_GATE_AREA) |
3874 | |
3875 | #if defined(AT_SYSINFO_EHDR) |
3876 | static struct vm_area_struct gate_vma; |
3877 | |
3878 | static int __init gate_vma_init(void) |
3879 | { |
3880 | gate_vma.vm_mm = NULL; |
3881 | gate_vma.vm_start = FIXADDR_USER_START; |
3882 | gate_vma.vm_end = FIXADDR_USER_END; |
3883 | gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; |
3884 | gate_vma.vm_page_prot = __P101; |
3885 | |
3886 | return 0; |
3887 | } |
3888 | __initcall(gate_vma_init); |
3889 | #endif |
3890 | |
3891 | struct vm_area_struct *get_gate_vma(struct mm_struct *mm) |
3892 | { |
3893 | #ifdef AT_SYSINFO_EHDR |
3894 | return &gate_vma; |
3895 | #else |
3896 | return NULL; |
3897 | #endif |
3898 | } |
3899 | |
3900 | int in_gate_area_no_mm(unsigned long addr) |
3901 | { |
3902 | #ifdef AT_SYSINFO_EHDR |
3903 | if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) |
3904 | return 1; |
3905 | #endif |
3906 | return 0; |
3907 | } |
3908 | |
3909 | #endif /* __HAVE_ARCH_GATE_AREA */ |
3910 | |
3911 | static int __follow_pte(struct mm_struct *mm, unsigned long address, |
3912 | pte_t **ptepp, spinlock_t **ptlp) |
3913 | { |
3914 | pgd_t *pgd; |
3915 | pud_t *pud; |
3916 | pmd_t *pmd; |
3917 | pte_t *ptep; |
3918 | |
3919 | pgd = pgd_offset(mm, address); |
3920 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
3921 | goto out; |
3922 | |
3923 | pud = pud_offset(pgd, address); |
3924 | if (pud_none(*pud) || unlikely(pud_bad(*pud))) |
3925 | goto out; |
3926 | |
3927 | pmd = pmd_offset(pud, address); |
3928 | VM_BUG_ON(pmd_trans_huge(*pmd)); |
3929 | if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
3930 | goto out; |
3931 | |
3932 | /* We cannot handle huge page PFN maps. Luckily they don't exist. */ |
3933 | if (pmd_huge(*pmd)) |
3934 | goto out; |
3935 | |
3936 | ptep = pte_offset_map_lock(mm, pmd, address, ptlp); |
3937 | if (!ptep) |
3938 | goto out; |
3939 | if (!pte_present(*ptep)) |
3940 | goto unlock; |
3941 | *ptepp = ptep; |
3942 | return 0; |
3943 | unlock: |
3944 | pte_unmap_unlock(ptep, *ptlp); |
3945 | out: |
3946 | return -EINVAL; |
3947 | } |
3948 | |
3949 | static inline int follow_pte(struct mm_struct *mm, unsigned long address, |
3950 | pte_t **ptepp, spinlock_t **ptlp) |
3951 | { |
3952 | int res; |
3953 | |
3954 | /* (void) is needed to make gcc happy */ |
3955 | (void) __cond_lock(*ptlp, |
3956 | !(res = __follow_pte(mm, address, ptepp, ptlp))); |
3957 | return res; |
3958 | } |
3959 | |
3960 | /** |
3961 | * follow_pfn - look up PFN at a user virtual address |
3962 | * @vma: memory mapping |
3963 | * @address: user virtual address |
3964 | * @pfn: location to store found PFN |
3965 | * |
3966 | * Only IO mappings and raw PFN mappings are allowed. |
3967 | * |
3968 | * Returns zero and the pfn at @pfn on success, -ve otherwise. |
3969 | */ |
3970 | int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
3971 | unsigned long *pfn) |
3972 | { |
3973 | int ret = -EINVAL; |
3974 | spinlock_t *ptl; |
3975 | pte_t *ptep; |
3976 | |
3977 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
3978 | return ret; |
3979 | |
3980 | ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); |
3981 | if (ret) |
3982 | return ret; |
3983 | *pfn = pte_pfn(*ptep); |
3984 | pte_unmap_unlock(ptep, ptl); |
3985 | return 0; |
3986 | } |
3987 | EXPORT_SYMBOL(follow_pfn); |
3988 | |
3989 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
3990 | int follow_phys(struct vm_area_struct *vma, |
3991 | unsigned long address, unsigned int flags, |
3992 | unsigned long *prot, resource_size_t *phys) |
3993 | { |
3994 | int ret = -EINVAL; |
3995 | pte_t *ptep, pte; |
3996 | spinlock_t *ptl; |
3997 | |
3998 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
3999 | goto out; |
4000 | |
4001 | if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) |
4002 | goto out; |
4003 | pte = *ptep; |
4004 | |
4005 | if ((flags & FOLL_WRITE) && !pte_write(pte)) |
4006 | goto unlock; |
4007 | |
4008 | *prot = pgprot_val(pte_pgprot(pte)); |
4009 | *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; |
4010 | |
4011 | ret = 0; |
4012 | unlock: |
4013 | pte_unmap_unlock(ptep, ptl); |
4014 | out: |
4015 | return ret; |
4016 | } |
4017 | |
4018 | int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, |
4019 | void *buf, int len, int write) |
4020 | { |
4021 | resource_size_t phys_addr; |
4022 | unsigned long prot = 0; |
4023 | void __iomem *maddr; |
4024 | int offset = addr & (PAGE_SIZE-1); |
4025 | |
4026 | if (follow_phys(vma, addr, write, &prot, &phys_addr)) |
4027 | return -EINVAL; |
4028 | |
4029 | maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); |
4030 | if (write) |
4031 | memcpy_toio(maddr + offset, buf, len); |
4032 | else |
4033 | memcpy_fromio(buf, maddr + offset, len); |
4034 | iounmap(maddr); |
4035 | |
4036 | return len; |
4037 | } |
4038 | EXPORT_SYMBOL_GPL(generic_access_phys); |
4039 | #endif |
4040 | |
4041 | /* |
4042 | * Access another process' address space as given in mm. If non-NULL, use the |
4043 | * given task for page fault accounting. |
4044 | */ |
4045 | static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, |
4046 | unsigned long addr, void *buf, int len, int write) |
4047 | { |
4048 | struct vm_area_struct *vma; |
4049 | void *old_buf = buf; |
4050 | |
4051 | down_read(&mm->mmap_sem); |
4052 | /* ignore errors, just check how much was successfully transferred */ |
4053 | while (len) { |
4054 | int bytes, ret, offset; |
4055 | void *maddr; |
4056 | struct page *page = NULL; |
4057 | |
4058 | ret = get_user_pages(tsk, mm, addr, 1, |
4059 | write, 1, &page, &vma); |
4060 | if (ret <= 0) { |
4061 | /* |
4062 | * Check if this is a VM_IO | VM_PFNMAP VMA, which |
4063 | * we can access using slightly different code. |
4064 | */ |
4065 | #ifdef CONFIG_HAVE_IOREMAP_PROT |
4066 | vma = find_vma(mm, addr); |
4067 | if (!vma || vma->vm_start > addr) |
4068 | break; |
4069 | if (vma->vm_ops && vma->vm_ops->access) |
4070 | ret = vma->vm_ops->access(vma, addr, buf, |
4071 | len, write); |
4072 | if (ret <= 0) |
4073 | #endif |
4074 | break; |
4075 | bytes = ret; |
4076 | } else { |
4077 | bytes = len; |
4078 | offset = addr & (PAGE_SIZE-1); |
4079 | if (bytes > PAGE_SIZE-offset) |
4080 | bytes = PAGE_SIZE-offset; |
4081 | |
4082 | maddr = kmap(page); |
4083 | if (write) { |
4084 | copy_to_user_page(vma, page, addr, |
4085 | maddr + offset, buf, bytes); |
4086 | set_page_dirty_lock(page); |
4087 | } else { |
4088 | copy_from_user_page(vma, page, addr, |
4089 | buf, maddr + offset, bytes); |
4090 | } |
4091 | kunmap(page); |
4092 | page_cache_release(page); |
4093 | } |
4094 | len -= bytes; |
4095 | buf += bytes; |
4096 | addr += bytes; |
4097 | } |
4098 | up_read(&mm->mmap_sem); |
4099 | |
4100 | return buf - old_buf; |
4101 | } |
4102 | |
4103 | /** |
4104 | * access_remote_vm - access another process' address space |
4105 | * @mm: the mm_struct of the target address space |
4106 | * @addr: start address to access |
4107 | * @buf: source or destination buffer |
4108 | * @len: number of bytes to transfer |
4109 | * @write: whether the access is a write |
4110 | * |
4111 | * The caller must hold a reference on @mm. |
4112 | */ |
4113 | int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
4114 | void *buf, int len, int write) |
4115 | { |
4116 | return __access_remote_vm(NULL, mm, addr, buf, len, write); |
4117 | } |
4118 | |
4119 | /* |
4120 | * Access another process' address space. |
4121 | * Source/target buffer must be kernel space, |
4122 | * Do not walk the page table directly, use get_user_pages |
4123 | */ |
4124 | int access_process_vm(struct task_struct *tsk, unsigned long addr, |
4125 | void *buf, int len, int write) |
4126 | { |
4127 | struct mm_struct *mm; |
4128 | int ret; |
4129 | |
4130 | mm = get_task_mm(tsk); |
4131 | if (!mm) |
4132 | return 0; |
4133 | |
4134 | ret = __access_remote_vm(tsk, mm, addr, buf, len, write); |
4135 | mmput(mm); |
4136 | |
4137 | return ret; |
4138 | } |
4139 | |
4140 | /* |
4141 | * Print the name of a VMA. |
4142 | */ |
4143 | void print_vma_addr(char *prefix, unsigned long ip) |
4144 | { |
4145 | struct mm_struct *mm = current->mm; |
4146 | struct vm_area_struct *vma; |
4147 | |
4148 | /* |
4149 | * Do not print if we are in atomic |
4150 | * contexts (in exception stacks, etc.): |
4151 | */ |
4152 | if (preempt_count()) |
4153 | return; |
4154 | |
4155 | down_read(&mm->mmap_sem); |
4156 | vma = find_vma(mm, ip); |
4157 | if (vma && vma->vm_file) { |
4158 | struct file *f = vma->vm_file; |
4159 | char *buf = (char *)__get_free_page(GFP_KERNEL); |
4160 | if (buf) { |
4161 | char *p; |
4162 | |
4163 | p = d_path(&f->f_path, buf, PAGE_SIZE); |
4164 | if (IS_ERR(p)) |
4165 | p = "?"; |
4166 | printk("%s%s[%lx+%lx]", prefix, kbasename(p), |
4167 | vma->vm_start, |
4168 | vma->vm_end - vma->vm_start); |
4169 | free_page((unsigned long)buf); |
4170 | } |
4171 | } |
4172 | up_read(&mm->mmap_sem); |
4173 | } |
4174 | |
4175 | #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) |
4176 | void might_fault(void) |
4177 | { |
4178 | /* |
4179 | * Some code (nfs/sunrpc) uses socket ops on kernel memory while |
4180 | * holding the mmap_sem, this is safe because kernel memory doesn't |
4181 | * get paged out, therefore we'll never actually fault, and the |
4182 | * below annotations will generate false positives. |
4183 | */ |
4184 | if (segment_eq(get_fs(), KERNEL_DS)) |
4185 | return; |
4186 | |
4187 | /* |
4188 | * it would be nicer only to annotate paths which are not under |
4189 | * pagefault_disable, however that requires a larger audit and |
4190 | * providing helpers like get_user_atomic. |
4191 | */ |
4192 | if (in_atomic()) |
4193 | return; |
4194 | |
4195 | __might_sleep(__FILE__, __LINE__, 0); |
4196 | |
4197 | if (current->mm) |
4198 | might_lock_read(¤t->mm->mmap_sem); |
4199 | } |
4200 | EXPORT_SYMBOL(might_fault); |
4201 | #endif |
4202 | |
4203 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) |
4204 | static void clear_gigantic_page(struct page *page, |
4205 | unsigned long addr, |
4206 | unsigned int pages_per_huge_page) |
4207 | { |
4208 | int i; |
4209 | struct page *p = page; |
4210 | |
4211 | might_sleep(); |
4212 | for (i = 0; i < pages_per_huge_page; |
4213 | i++, p = mem_map_next(p, page, i)) { |
4214 | cond_resched(); |
4215 | clear_user_highpage(p, addr + i * PAGE_SIZE); |
4216 | } |
4217 | } |
4218 | void clear_huge_page(struct page *page, |
4219 | unsigned long addr, unsigned int pages_per_huge_page) |
4220 | { |
4221 | int i; |
4222 | |
4223 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
4224 | clear_gigantic_page(page, addr, pages_per_huge_page); |
4225 | return; |
4226 | } |
4227 | |
4228 | might_sleep(); |
4229 | for (i = 0; i < pages_per_huge_page; i++) { |
4230 | cond_resched(); |
4231 | clear_user_highpage(page + i, addr + i * PAGE_SIZE); |
4232 | } |
4233 | } |
4234 | |
4235 | static void copy_user_gigantic_page(struct page *dst, struct page *src, |
4236 | unsigned long addr, |
4237 | struct vm_area_struct *vma, |
4238 | unsigned int pages_per_huge_page) |
4239 | { |
4240 | int i; |
4241 | struct page *dst_base = dst; |
4242 | struct page *src_base = src; |
4243 | |
4244 | for (i = 0; i < pages_per_huge_page; ) { |
4245 | cond_resched(); |
4246 | copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); |
4247 | |
4248 | i++; |
4249 | dst = mem_map_next(dst, dst_base, i); |
4250 | src = mem_map_next(src, src_base, i); |
4251 | } |
4252 | } |
4253 | |
4254 | void copy_user_huge_page(struct page *dst, struct page *src, |
4255 | unsigned long addr, struct vm_area_struct *vma, |
4256 | unsigned int pages_per_huge_page) |
4257 | { |
4258 | int i; |
4259 | |
4260 | if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { |
4261 | copy_user_gigantic_page(dst, src, addr, vma, |
4262 | pages_per_huge_page); |
4263 | return; |
4264 | } |
4265 | |
4266 | might_sleep(); |
4267 | for (i = 0; i < pages_per_huge_page; i++) { |
4268 | cond_resched(); |
4269 | copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); |
4270 | } |
4271 | } |
4272 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ |
4273 | |
4274 | #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS |
4275 | bool ptlock_alloc(struct page *page) |
4276 | { |
4277 | spinlock_t *ptl; |
4278 | |
4279 | ptl = kmalloc(sizeof(spinlock_t), GFP_KERNEL); |
4280 | if (!ptl) |
4281 | return false; |
4282 | page->ptl = ptl; |
4283 | return true; |
4284 | } |
4285 | |
4286 | void ptlock_free(struct page *page) |
4287 | { |
4288 | kfree(page->ptl); |
4289 | } |
4290 | #endif |
4291 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9