Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/mm/memory.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 60685 byte(s)
Tag kernel26-2.6.12-alx-r9
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/rmap.h> |
49 | #include <linux/module.h> |
50 | #include <linux/init.h> |
51 | |
52 | #include <asm/pgalloc.h> |
53 | #include <asm/uaccess.h> |
54 | #include <asm/tlb.h> |
55 | #include <asm/tlbflush.h> |
56 | #include <asm/pgtable.h> |
57 | |
58 | #include <linux/swapops.h> |
59 | #include <linux/elf.h> |
60 | |
61 | #ifndef CONFIG_DISCONTIGMEM |
62 | /* use the per-pgdat data instead for discontigmem - mbligh */ |
63 | unsigned long max_mapnr; |
64 | struct page *mem_map; |
65 | |
66 | EXPORT_SYMBOL(max_mapnr); |
67 | EXPORT_SYMBOL(mem_map); |
68 | #endif |
69 | |
70 | unsigned long num_physpages; |
71 | /* |
72 | * A number of key systems in x86 including ioremap() rely on the assumption |
73 | * that high_memory defines the upper bound on direct map memory, then end |
74 | * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and |
75 | * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL |
76 | * and ZONE_HIGHMEM. |
77 | */ |
78 | void * high_memory; |
79 | unsigned long vmalloc_earlyreserve; |
80 | |
81 | EXPORT_SYMBOL(num_physpages); |
82 | EXPORT_SYMBOL(high_memory); |
83 | EXPORT_SYMBOL(vmalloc_earlyreserve); |
84 | |
85 | /* |
86 | * If a p?d_bad entry is found while walking page tables, report |
87 | * the error, before resetting entry to p?d_none. Usually (but |
88 | * very seldom) called out from the p?d_none_or_clear_bad macros. |
89 | */ |
90 | |
91 | void pgd_clear_bad(pgd_t *pgd) |
92 | { |
93 | pgd_ERROR(*pgd); |
94 | pgd_clear(pgd); |
95 | } |
96 | |
97 | void pud_clear_bad(pud_t *pud) |
98 | { |
99 | pud_ERROR(*pud); |
100 | pud_clear(pud); |
101 | } |
102 | |
103 | void pmd_clear_bad(pmd_t *pmd) |
104 | { |
105 | pmd_ERROR(*pmd); |
106 | pmd_clear(pmd); |
107 | } |
108 | |
109 | /* |
110 | * Note: this doesn't free the actual pages themselves. That |
111 | * has been handled earlier when unmapping all the memory regions. |
112 | */ |
113 | static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) |
114 | { |
115 | struct page *page = pmd_page(*pmd); |
116 | pmd_clear(pmd); |
117 | pte_free_tlb(tlb, page); |
118 | dec_page_state(nr_page_table_pages); |
119 | tlb->mm->nr_ptes--; |
120 | } |
121 | |
122 | static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
123 | unsigned long addr, unsigned long end, |
124 | unsigned long floor, unsigned long ceiling) |
125 | { |
126 | pmd_t *pmd; |
127 | unsigned long next; |
128 | unsigned long start; |
129 | |
130 | start = addr; |
131 | pmd = pmd_offset(pud, addr); |
132 | do { |
133 | next = pmd_addr_end(addr, end); |
134 | if (pmd_none_or_clear_bad(pmd)) |
135 | continue; |
136 | free_pte_range(tlb, pmd); |
137 | } while (pmd++, addr = next, addr != end); |
138 | |
139 | start &= PUD_MASK; |
140 | if (start < floor) |
141 | return; |
142 | if (ceiling) { |
143 | ceiling &= PUD_MASK; |
144 | if (!ceiling) |
145 | return; |
146 | } |
147 | if (end - 1 > ceiling - 1) |
148 | return; |
149 | |
150 | pmd = pmd_offset(pud, start); |
151 | pud_clear(pud); |
152 | pmd_free_tlb(tlb, pmd); |
153 | } |
154 | |
155 | static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, |
156 | unsigned long addr, unsigned long end, |
157 | unsigned long floor, unsigned long ceiling) |
158 | { |
159 | pud_t *pud; |
160 | unsigned long next; |
161 | unsigned long start; |
162 | |
163 | start = addr; |
164 | pud = pud_offset(pgd, addr); |
165 | do { |
166 | next = pud_addr_end(addr, end); |
167 | if (pud_none_or_clear_bad(pud)) |
168 | continue; |
169 | free_pmd_range(tlb, pud, addr, next, floor, ceiling); |
170 | } while (pud++, addr = next, addr != end); |
171 | |
172 | start &= PGDIR_MASK; |
173 | if (start < floor) |
174 | return; |
175 | if (ceiling) { |
176 | ceiling &= PGDIR_MASK; |
177 | if (!ceiling) |
178 | return; |
179 | } |
180 | if (end - 1 > ceiling - 1) |
181 | return; |
182 | |
183 | pud = pud_offset(pgd, start); |
184 | pgd_clear(pgd); |
185 | pud_free_tlb(tlb, pud); |
186 | } |
187 | |
188 | /* |
189 | * This function frees user-level page tables of a process. |
190 | * |
191 | * Must be called with pagetable lock held. |
192 | */ |
193 | void free_pgd_range(struct mmu_gather **tlb, |
194 | unsigned long addr, unsigned long end, |
195 | unsigned long floor, unsigned long ceiling) |
196 | { |
197 | pgd_t *pgd; |
198 | unsigned long next; |
199 | unsigned long start; |
200 | |
201 | /* |
202 | * The next few lines have given us lots of grief... |
203 | * |
204 | * Why are we testing PMD* at this top level? Because often |
205 | * there will be no work to do at all, and we'd prefer not to |
206 | * go all the way down to the bottom just to discover that. |
207 | * |
208 | * Why all these "- 1"s? Because 0 represents both the bottom |
209 | * of the address space and the top of it (using -1 for the |
210 | * top wouldn't help much: the masks would do the wrong thing). |
211 | * The rule is that addr 0 and floor 0 refer to the bottom of |
212 | * the address space, but end 0 and ceiling 0 refer to the top |
213 | * Comparisons need to use "end - 1" and "ceiling - 1" (though |
214 | * that end 0 case should be mythical). |
215 | * |
216 | * Wherever addr is brought up or ceiling brought down, we must |
217 | * be careful to reject "the opposite 0" before it confuses the |
218 | * subsequent tests. But what about where end is brought down |
219 | * by PMD_SIZE below? no, end can't go down to 0 there. |
220 | * |
221 | * Whereas we round start (addr) and ceiling down, by different |
222 | * masks at different levels, in order to test whether a table |
223 | * now has no other vmas using it, so can be freed, we don't |
224 | * bother to round floor or end up - the tests don't need that. |
225 | */ |
226 | |
227 | addr &= PMD_MASK; |
228 | if (addr < floor) { |
229 | addr += PMD_SIZE; |
230 | if (!addr) |
231 | return; |
232 | } |
233 | if (ceiling) { |
234 | ceiling &= PMD_MASK; |
235 | if (!ceiling) |
236 | return; |
237 | } |
238 | if (end - 1 > ceiling - 1) |
239 | end -= PMD_SIZE; |
240 | if (addr > end - 1) |
241 | return; |
242 | |
243 | start = addr; |
244 | pgd = pgd_offset((*tlb)->mm, addr); |
245 | do { |
246 | next = pgd_addr_end(addr, end); |
247 | if (pgd_none_or_clear_bad(pgd)) |
248 | continue; |
249 | free_pud_range(*tlb, pgd, addr, next, floor, ceiling); |
250 | } while (pgd++, addr = next, addr != end); |
251 | |
252 | if (!tlb_is_full_mm(*tlb)) |
253 | flush_tlb_pgtables((*tlb)->mm, start, end); |
254 | } |
255 | |
256 | void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, |
257 | unsigned long floor, unsigned long ceiling) |
258 | { |
259 | while (vma) { |
260 | struct vm_area_struct *next = vma->vm_next; |
261 | unsigned long addr = vma->vm_start; |
262 | |
263 | if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) { |
264 | hugetlb_free_pgd_range(tlb, addr, vma->vm_end, |
265 | floor, next? next->vm_start: ceiling); |
266 | } else { |
267 | /* |
268 | * Optimization: gather nearby vmas into one call down |
269 | */ |
270 | while (next && next->vm_start <= vma->vm_end + PMD_SIZE |
271 | && !is_hugepage_only_range(vma->vm_mm, next->vm_start, |
272 | HPAGE_SIZE)) { |
273 | vma = next; |
274 | next = vma->vm_next; |
275 | } |
276 | free_pgd_range(tlb, addr, vma->vm_end, |
277 | floor, next? next->vm_start: ceiling); |
278 | } |
279 | vma = next; |
280 | } |
281 | } |
282 | |
283 | pte_t fastcall *pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, |
284 | unsigned long address) |
285 | { |
286 | if (!pmd_present(*pmd)) { |
287 | struct page *new; |
288 | |
289 | spin_unlock(&mm->page_table_lock); |
290 | new = pte_alloc_one(mm, address); |
291 | spin_lock(&mm->page_table_lock); |
292 | if (!new) |
293 | return NULL; |
294 | /* |
295 | * Because we dropped the lock, we should re-check the |
296 | * entry, as somebody else could have populated it.. |
297 | */ |
298 | if (pmd_present(*pmd)) { |
299 | pte_free(new); |
300 | goto out; |
301 | } |
302 | mm->nr_ptes++; |
303 | inc_page_state(nr_page_table_pages); |
304 | pmd_populate(mm, pmd, new); |
305 | } |
306 | out: |
307 | return pte_offset_map(pmd, address); |
308 | } |
309 | |
310 | pte_t fastcall * pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsigned long address) |
311 | { |
312 | if (!pmd_present(*pmd)) { |
313 | pte_t *new; |
314 | |
315 | spin_unlock(&mm->page_table_lock); |
316 | new = pte_alloc_one_kernel(mm, address); |
317 | spin_lock(&mm->page_table_lock); |
318 | if (!new) |
319 | return NULL; |
320 | |
321 | /* |
322 | * Because we dropped the lock, we should re-check the |
323 | * entry, as somebody else could have populated it.. |
324 | */ |
325 | if (pmd_present(*pmd)) { |
326 | pte_free_kernel(new); |
327 | goto out; |
328 | } |
329 | pmd_populate_kernel(mm, pmd, new); |
330 | } |
331 | out: |
332 | return pte_offset_kernel(pmd, address); |
333 | } |
334 | |
335 | /* |
336 | * copy one vm_area from one task to the other. Assumes the page tables |
337 | * already present in the new task to be cleared in the whole range |
338 | * covered by this vma. |
339 | * |
340 | * dst->page_table_lock is held on entry and exit, |
341 | * but may be dropped within p[mg]d_alloc() and pte_alloc_map(). |
342 | */ |
343 | |
344 | static inline void |
345 | copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
346 | pte_t *dst_pte, pte_t *src_pte, unsigned long vm_flags, |
347 | unsigned long addr) |
348 | { |
349 | pte_t pte = *src_pte; |
350 | struct page *page; |
351 | unsigned long pfn; |
352 | |
353 | /* pte contains position in swap or file, so copy. */ |
354 | if (unlikely(!pte_present(pte))) { |
355 | if (!pte_file(pte)) { |
356 | swap_duplicate(pte_to_swp_entry(pte)); |
357 | /* make sure dst_mm is on swapoff's mmlist. */ |
358 | if (unlikely(list_empty(&dst_mm->mmlist))) { |
359 | spin_lock(&mmlist_lock); |
360 | list_add(&dst_mm->mmlist, &src_mm->mmlist); |
361 | spin_unlock(&mmlist_lock); |
362 | } |
363 | } |
364 | set_pte_at(dst_mm, addr, dst_pte, pte); |
365 | return; |
366 | } |
367 | |
368 | pfn = pte_pfn(pte); |
369 | /* the pte points outside of valid memory, the |
370 | * mapping is assumed to be good, meaningful |
371 | * and not mapped via rmap - duplicate the |
372 | * mapping as is. |
373 | */ |
374 | page = NULL; |
375 | if (pfn_valid(pfn)) |
376 | page = pfn_to_page(pfn); |
377 | |
378 | if (!page || PageReserved(page)) { |
379 | set_pte_at(dst_mm, addr, dst_pte, pte); |
380 | return; |
381 | } |
382 | |
383 | /* |
384 | * If it's a COW mapping, write protect it both |
385 | * in the parent and the child |
386 | */ |
387 | if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) { |
388 | ptep_set_wrprotect(src_mm, addr, src_pte); |
389 | pte = *src_pte; |
390 | } |
391 | |
392 | /* |
393 | * If it's a shared mapping, mark it clean in |
394 | * the child |
395 | */ |
396 | if (vm_flags & VM_SHARED) |
397 | pte = pte_mkclean(pte); |
398 | pte = pte_mkold(pte); |
399 | get_page(page); |
400 | inc_mm_counter(dst_mm, rss); |
401 | if (PageAnon(page)) |
402 | inc_mm_counter(dst_mm, anon_rss); |
403 | set_pte_at(dst_mm, addr, dst_pte, pte); |
404 | page_dup_rmap(page); |
405 | } |
406 | |
407 | static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
408 | pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, |
409 | unsigned long addr, unsigned long end) |
410 | { |
411 | pte_t *src_pte, *dst_pte; |
412 | unsigned long vm_flags = vma->vm_flags; |
413 | int progress; |
414 | |
415 | again: |
416 | dst_pte = pte_alloc_map(dst_mm, dst_pmd, addr); |
417 | if (!dst_pte) |
418 | return -ENOMEM; |
419 | src_pte = pte_offset_map_nested(src_pmd, addr); |
420 | |
421 | progress = 0; |
422 | spin_lock(&src_mm->page_table_lock); |
423 | do { |
424 | /* |
425 | * We are holding two locks at this point - either of them |
426 | * could generate latencies in another task on another CPU. |
427 | */ |
428 | if (progress >= 32 && (need_resched() || |
429 | need_lockbreak(&src_mm->page_table_lock) || |
430 | need_lockbreak(&dst_mm->page_table_lock))) |
431 | break; |
432 | if (pte_none(*src_pte)) { |
433 | progress++; |
434 | continue; |
435 | } |
436 | copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vm_flags, addr); |
437 | progress += 8; |
438 | } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); |
439 | spin_unlock(&src_mm->page_table_lock); |
440 | |
441 | pte_unmap_nested(src_pte - 1); |
442 | pte_unmap(dst_pte - 1); |
443 | cond_resched_lock(&dst_mm->page_table_lock); |
444 | if (addr != end) |
445 | goto again; |
446 | return 0; |
447 | } |
448 | |
449 | static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
450 | pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, |
451 | unsigned long addr, unsigned long end) |
452 | { |
453 | pmd_t *src_pmd, *dst_pmd; |
454 | unsigned long next; |
455 | |
456 | dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); |
457 | if (!dst_pmd) |
458 | return -ENOMEM; |
459 | src_pmd = pmd_offset(src_pud, addr); |
460 | do { |
461 | next = pmd_addr_end(addr, end); |
462 | if (pmd_none_or_clear_bad(src_pmd)) |
463 | continue; |
464 | if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, |
465 | vma, addr, next)) |
466 | return -ENOMEM; |
467 | } while (dst_pmd++, src_pmd++, addr = next, addr != end); |
468 | return 0; |
469 | } |
470 | |
471 | static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
472 | pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, |
473 | unsigned long addr, unsigned long end) |
474 | { |
475 | pud_t *src_pud, *dst_pud; |
476 | unsigned long next; |
477 | |
478 | dst_pud = pud_alloc(dst_mm, dst_pgd, addr); |
479 | if (!dst_pud) |
480 | return -ENOMEM; |
481 | src_pud = pud_offset(src_pgd, addr); |
482 | do { |
483 | next = pud_addr_end(addr, end); |
484 | if (pud_none_or_clear_bad(src_pud)) |
485 | continue; |
486 | if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, |
487 | vma, addr, next)) |
488 | return -ENOMEM; |
489 | } while (dst_pud++, src_pud++, addr = next, addr != end); |
490 | return 0; |
491 | } |
492 | |
493 | int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
494 | struct vm_area_struct *vma) |
495 | { |
496 | pgd_t *src_pgd, *dst_pgd; |
497 | unsigned long next; |
498 | unsigned long addr = vma->vm_start; |
499 | unsigned long end = vma->vm_end; |
500 | |
501 | if (is_vm_hugetlb_page(vma)) |
502 | return copy_hugetlb_page_range(dst_mm, src_mm, vma); |
503 | |
504 | dst_pgd = pgd_offset(dst_mm, addr); |
505 | src_pgd = pgd_offset(src_mm, addr); |
506 | do { |
507 | next = pgd_addr_end(addr, end); |
508 | if (pgd_none_or_clear_bad(src_pgd)) |
509 | continue; |
510 | if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, |
511 | vma, addr, next)) |
512 | return -ENOMEM; |
513 | } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
514 | return 0; |
515 | } |
516 | |
517 | static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd, |
518 | unsigned long addr, unsigned long end, |
519 | struct zap_details *details) |
520 | { |
521 | pte_t *pte; |
522 | |
523 | pte = pte_offset_map(pmd, addr); |
524 | do { |
525 | pte_t ptent = *pte; |
526 | if (pte_none(ptent)) |
527 | continue; |
528 | if (pte_present(ptent)) { |
529 | struct page *page = NULL; |
530 | unsigned long pfn = pte_pfn(ptent); |
531 | if (pfn_valid(pfn)) { |
532 | page = pfn_to_page(pfn); |
533 | if (PageReserved(page)) |
534 | page = NULL; |
535 | } |
536 | if (unlikely(details) && page) { |
537 | /* |
538 | * unmap_shared_mapping_pages() wants to |
539 | * invalidate cache without truncating: |
540 | * unmap shared but keep private pages. |
541 | */ |
542 | if (details->check_mapping && |
543 | details->check_mapping != page->mapping) |
544 | continue; |
545 | /* |
546 | * Each page->index must be checked when |
547 | * invalidating or truncating nonlinear. |
548 | */ |
549 | if (details->nonlinear_vma && |
550 | (page->index < details->first_index || |
551 | page->index > details->last_index)) |
552 | continue; |
553 | } |
554 | ptent = ptep_get_and_clear(tlb->mm, addr, pte); |
555 | tlb_remove_tlb_entry(tlb, pte, addr); |
556 | if (unlikely(!page)) |
557 | continue; |
558 | if (unlikely(details) && details->nonlinear_vma |
559 | && linear_page_index(details->nonlinear_vma, |
560 | addr) != page->index) |
561 | set_pte_at(tlb->mm, addr, pte, |
562 | pgoff_to_pte(page->index)); |
563 | if (pte_dirty(ptent)) |
564 | set_page_dirty(page); |
565 | if (PageAnon(page)) |
566 | dec_mm_counter(tlb->mm, anon_rss); |
567 | else if (pte_young(ptent)) |
568 | mark_page_accessed(page); |
569 | tlb->freed++; |
570 | page_remove_rmap(page); |
571 | tlb_remove_page(tlb, page); |
572 | continue; |
573 | } |
574 | /* |
575 | * If details->check_mapping, we leave swap entries; |
576 | * if details->nonlinear_vma, we leave file entries. |
577 | */ |
578 | if (unlikely(details)) |
579 | continue; |
580 | if (!pte_file(ptent)) |
581 | free_swap_and_cache(pte_to_swp_entry(ptent)); |
582 | pte_clear(tlb->mm, addr, pte); |
583 | } while (pte++, addr += PAGE_SIZE, addr != end); |
584 | pte_unmap(pte - 1); |
585 | } |
586 | |
587 | static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
588 | unsigned long addr, unsigned long end, |
589 | struct zap_details *details) |
590 | { |
591 | pmd_t *pmd; |
592 | unsigned long next; |
593 | |
594 | pmd = pmd_offset(pud, addr); |
595 | do { |
596 | next = pmd_addr_end(addr, end); |
597 | if (pmd_none_or_clear_bad(pmd)) |
598 | continue; |
599 | zap_pte_range(tlb, pmd, addr, next, details); |
600 | } while (pmd++, addr = next, addr != end); |
601 | } |
602 | |
603 | static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd, |
604 | unsigned long addr, unsigned long end, |
605 | struct zap_details *details) |
606 | { |
607 | pud_t *pud; |
608 | unsigned long next; |
609 | |
610 | pud = pud_offset(pgd, addr); |
611 | do { |
612 | next = pud_addr_end(addr, end); |
613 | if (pud_none_or_clear_bad(pud)) |
614 | continue; |
615 | zap_pmd_range(tlb, pud, addr, next, details); |
616 | } while (pud++, addr = next, addr != end); |
617 | } |
618 | |
619 | static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, |
620 | unsigned long addr, unsigned long end, |
621 | struct zap_details *details) |
622 | { |
623 | pgd_t *pgd; |
624 | unsigned long next; |
625 | |
626 | if (details && !details->check_mapping && !details->nonlinear_vma) |
627 | details = NULL; |
628 | |
629 | BUG_ON(addr >= end); |
630 | tlb_start_vma(tlb, vma); |
631 | pgd = pgd_offset(vma->vm_mm, addr); |
632 | do { |
633 | next = pgd_addr_end(addr, end); |
634 | if (pgd_none_or_clear_bad(pgd)) |
635 | continue; |
636 | zap_pud_range(tlb, pgd, addr, next, details); |
637 | } while (pgd++, addr = next, addr != end); |
638 | tlb_end_vma(tlb, vma); |
639 | } |
640 | |
641 | #ifdef CONFIG_PREEMPT |
642 | # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) |
643 | #else |
644 | /* No preempt: go for improved straight-line efficiency */ |
645 | # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) |
646 | #endif |
647 | |
648 | /** |
649 | * unmap_vmas - unmap a range of memory covered by a list of vma's |
650 | * @tlbp: address of the caller's struct mmu_gather |
651 | * @mm: the controlling mm_struct |
652 | * @vma: the starting vma |
653 | * @start_addr: virtual address at which to start unmapping |
654 | * @end_addr: virtual address at which to end unmapping |
655 | * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here |
656 | * @details: details of nonlinear truncation or shared cache invalidation |
657 | * |
658 | * Returns the end address of the unmapping (restart addr if interrupted). |
659 | * |
660 | * Unmap all pages in the vma list. Called under page_table_lock. |
661 | * |
662 | * We aim to not hold page_table_lock for too long (for scheduling latency |
663 | * reasons). So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to |
664 | * return the ending mmu_gather to the caller. |
665 | * |
666 | * Only addresses between `start' and `end' will be unmapped. |
667 | * |
668 | * The VMA list must be sorted in ascending virtual address order. |
669 | * |
670 | * unmap_vmas() assumes that the caller will flush the whole unmapped address |
671 | * range after unmap_vmas() returns. So the only responsibility here is to |
672 | * ensure that any thus-far unmapped pages are flushed before unmap_vmas() |
673 | * drops the lock and schedules. |
674 | */ |
675 | unsigned long unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm, |
676 | struct vm_area_struct *vma, unsigned long start_addr, |
677 | unsigned long end_addr, unsigned long *nr_accounted, |
678 | struct zap_details *details) |
679 | { |
680 | unsigned long zap_bytes = ZAP_BLOCK_SIZE; |
681 | unsigned long tlb_start = 0; /* For tlb_finish_mmu */ |
682 | int tlb_start_valid = 0; |
683 | unsigned long start = start_addr; |
684 | spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; |
685 | int fullmm = tlb_is_full_mm(*tlbp); |
686 | |
687 | for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { |
688 | unsigned long end; |
689 | |
690 | start = max(vma->vm_start, start_addr); |
691 | if (start >= vma->vm_end) |
692 | continue; |
693 | end = min(vma->vm_end, end_addr); |
694 | if (end <= vma->vm_start) |
695 | continue; |
696 | |
697 | if (vma->vm_flags & VM_ACCOUNT) |
698 | *nr_accounted += (end - start) >> PAGE_SHIFT; |
699 | |
700 | while (start != end) { |
701 | unsigned long block; |
702 | |
703 | if (!tlb_start_valid) { |
704 | tlb_start = start; |
705 | tlb_start_valid = 1; |
706 | } |
707 | |
708 | if (is_vm_hugetlb_page(vma)) { |
709 | block = end - start; |
710 | unmap_hugepage_range(vma, start, end); |
711 | } else { |
712 | block = min(zap_bytes, end - start); |
713 | unmap_page_range(*tlbp, vma, start, |
714 | start + block, details); |
715 | } |
716 | |
717 | start += block; |
718 | zap_bytes -= block; |
719 | if ((long)zap_bytes > 0) |
720 | continue; |
721 | |
722 | tlb_finish_mmu(*tlbp, tlb_start, start); |
723 | |
724 | if (need_resched() || |
725 | need_lockbreak(&mm->page_table_lock) || |
726 | (i_mmap_lock && need_lockbreak(i_mmap_lock))) { |
727 | if (i_mmap_lock) { |
728 | /* must reset count of rss freed */ |
729 | *tlbp = tlb_gather_mmu(mm, fullmm); |
730 | goto out; |
731 | } |
732 | spin_unlock(&mm->page_table_lock); |
733 | cond_resched(); |
734 | spin_lock(&mm->page_table_lock); |
735 | } |
736 | |
737 | *tlbp = tlb_gather_mmu(mm, fullmm); |
738 | tlb_start_valid = 0; |
739 | zap_bytes = ZAP_BLOCK_SIZE; |
740 | } |
741 | } |
742 | out: |
743 | return start; /* which is now the end (or restart) address */ |
744 | } |
745 | |
746 | /** |
747 | * zap_page_range - remove user pages in a given range |
748 | * @vma: vm_area_struct holding the applicable pages |
749 | * @address: starting address of pages to zap |
750 | * @size: number of bytes to zap |
751 | * @details: details of nonlinear truncation or shared cache invalidation |
752 | */ |
753 | unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, |
754 | unsigned long size, struct zap_details *details) |
755 | { |
756 | struct mm_struct *mm = vma->vm_mm; |
757 | struct mmu_gather *tlb; |
758 | unsigned long end = address + size; |
759 | unsigned long nr_accounted = 0; |
760 | |
761 | if (is_vm_hugetlb_page(vma)) { |
762 | zap_hugepage_range(vma, address, size); |
763 | return end; |
764 | } |
765 | |
766 | lru_add_drain(); |
767 | spin_lock(&mm->page_table_lock); |
768 | tlb = tlb_gather_mmu(mm, 0); |
769 | end = unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details); |
770 | tlb_finish_mmu(tlb, address, end); |
771 | spin_unlock(&mm->page_table_lock); |
772 | return end; |
773 | } |
774 | |
775 | /* |
776 | * Do a quick page-table lookup for a single page. |
777 | * mm->page_table_lock must be held. |
778 | */ |
779 | static struct page * |
780 | __follow_page(struct mm_struct *mm, unsigned long address, int read, int write) |
781 | { |
782 | pgd_t *pgd; |
783 | pud_t *pud; |
784 | pmd_t *pmd; |
785 | pte_t *ptep, pte; |
786 | unsigned long pfn; |
787 | struct page *page; |
788 | |
789 | page = follow_huge_addr(mm, address, write); |
790 | if (! IS_ERR(page)) |
791 | return page; |
792 | |
793 | pgd = pgd_offset(mm, address); |
794 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
795 | goto out; |
796 | |
797 | pud = pud_offset(pgd, address); |
798 | if (pud_none(*pud) || unlikely(pud_bad(*pud))) |
799 | goto out; |
800 | |
801 | pmd = pmd_offset(pud, address); |
802 | if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
803 | goto out; |
804 | if (pmd_huge(*pmd)) |
805 | return follow_huge_pmd(mm, address, pmd, write); |
806 | |
807 | ptep = pte_offset_map(pmd, address); |
808 | if (!ptep) |
809 | goto out; |
810 | |
811 | pte = *ptep; |
812 | pte_unmap(ptep); |
813 | if (pte_present(pte)) { |
814 | if (write && !pte_write(pte)) |
815 | goto out; |
816 | if (read && !pte_read(pte)) |
817 | goto out; |
818 | pfn = pte_pfn(pte); |
819 | if (pfn_valid(pfn)) { |
820 | page = pfn_to_page(pfn); |
821 | if (write && !pte_dirty(pte) && !PageDirty(page)) |
822 | set_page_dirty(page); |
823 | mark_page_accessed(page); |
824 | return page; |
825 | } |
826 | } |
827 | |
828 | out: |
829 | return NULL; |
830 | } |
831 | |
832 | struct page * |
833 | follow_page(struct mm_struct *mm, unsigned long address, int write) |
834 | { |
835 | return __follow_page(mm, address, /*read*/0, write); |
836 | } |
837 | |
838 | int |
839 | check_user_page_readable(struct mm_struct *mm, unsigned long address) |
840 | { |
841 | return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL; |
842 | } |
843 | |
844 | EXPORT_SYMBOL(check_user_page_readable); |
845 | |
846 | /* |
847 | * Given a physical address, is there a useful struct page pointing to |
848 | * it? This may become more complex in the future if we start dealing |
849 | * with IO-aperture pages for direct-IO. |
850 | */ |
851 | |
852 | static inline struct page *get_page_map(struct page *page) |
853 | { |
854 | if (!pfn_valid(page_to_pfn(page))) |
855 | return NULL; |
856 | return page; |
857 | } |
858 | |
859 | |
860 | static inline int |
861 | untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma, |
862 | unsigned long address) |
863 | { |
864 | pgd_t *pgd; |
865 | pud_t *pud; |
866 | pmd_t *pmd; |
867 | |
868 | /* Check if the vma is for an anonymous mapping. */ |
869 | if (vma->vm_ops && vma->vm_ops->nopage) |
870 | return 0; |
871 | |
872 | /* Check if page directory entry exists. */ |
873 | pgd = pgd_offset(mm, address); |
874 | if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
875 | return 1; |
876 | |
877 | pud = pud_offset(pgd, address); |
878 | if (pud_none(*pud) || unlikely(pud_bad(*pud))) |
879 | return 1; |
880 | |
881 | /* Check if page middle directory entry exists. */ |
882 | pmd = pmd_offset(pud, address); |
883 | if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
884 | return 1; |
885 | |
886 | /* There is a pte slot for 'address' in 'mm'. */ |
887 | return 0; |
888 | } |
889 | |
890 | |
891 | int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
892 | unsigned long start, int len, int write, int force, |
893 | struct page **pages, struct vm_area_struct **vmas) |
894 | { |
895 | int i; |
896 | unsigned int flags; |
897 | |
898 | /* |
899 | * Require read or write permissions. |
900 | * If 'force' is set, we only require the "MAY" flags. |
901 | */ |
902 | flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); |
903 | flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); |
904 | i = 0; |
905 | |
906 | do { |
907 | struct vm_area_struct * vma; |
908 | |
909 | vma = find_extend_vma(mm, start); |
910 | if (!vma && in_gate_area(tsk, start)) { |
911 | unsigned long pg = start & PAGE_MASK; |
912 | struct vm_area_struct *gate_vma = get_gate_vma(tsk); |
913 | pgd_t *pgd; |
914 | pud_t *pud; |
915 | pmd_t *pmd; |
916 | pte_t *pte; |
917 | if (write) /* user gate pages are read-only */ |
918 | return i ? : -EFAULT; |
919 | if (pg > TASK_SIZE) |
920 | pgd = pgd_offset_k(pg); |
921 | else |
922 | pgd = pgd_offset_gate(mm, pg); |
923 | BUG_ON(pgd_none(*pgd)); |
924 | pud = pud_offset(pgd, pg); |
925 | BUG_ON(pud_none(*pud)); |
926 | pmd = pmd_offset(pud, pg); |
927 | BUG_ON(pmd_none(*pmd)); |
928 | pte = pte_offset_map(pmd, pg); |
929 | BUG_ON(pte_none(*pte)); |
930 | if (pages) { |
931 | pages[i] = pte_page(*pte); |
932 | get_page(pages[i]); |
933 | } |
934 | pte_unmap(pte); |
935 | if (vmas) |
936 | vmas[i] = gate_vma; |
937 | i++; |
938 | start += PAGE_SIZE; |
939 | len--; |
940 | continue; |
941 | } |
942 | |
943 | if (!vma || (vma->vm_flags & VM_IO) |
944 | || !(flags & vma->vm_flags)) |
945 | return i ? : -EFAULT; |
946 | |
947 | if (is_vm_hugetlb_page(vma)) { |
948 | i = follow_hugetlb_page(mm, vma, pages, vmas, |
949 | &start, &len, i); |
950 | continue; |
951 | } |
952 | spin_lock(&mm->page_table_lock); |
953 | do { |
954 | struct page *map; |
955 | int lookup_write = write; |
956 | |
957 | cond_resched_lock(&mm->page_table_lock); |
958 | while (!(map = follow_page(mm, start, lookup_write))) { |
959 | /* |
960 | * Shortcut for anonymous pages. We don't want |
961 | * to force the creation of pages tables for |
962 | * insanly big anonymously mapped areas that |
963 | * nobody touched so far. This is important |
964 | * for doing a core dump for these mappings. |
965 | */ |
966 | if (!lookup_write && |
967 | untouched_anonymous_page(mm,vma,start)) { |
968 | map = ZERO_PAGE(start); |
969 | break; |
970 | } |
971 | spin_unlock(&mm->page_table_lock); |
972 | switch (handle_mm_fault(mm,vma,start,write)) { |
973 | case VM_FAULT_MINOR: |
974 | tsk->min_flt++; |
975 | break; |
976 | case VM_FAULT_MAJOR: |
977 | tsk->maj_flt++; |
978 | break; |
979 | case VM_FAULT_SIGBUS: |
980 | return i ? i : -EFAULT; |
981 | case VM_FAULT_OOM: |
982 | return i ? i : -ENOMEM; |
983 | default: |
984 | BUG(); |
985 | } |
986 | /* |
987 | * Now that we have performed a write fault |
988 | * and surely no longer have a shared page we |
989 | * shouldn't write, we shouldn't ignore an |
990 | * unwritable page in the page table if |
991 | * we are forcing write access. |
992 | */ |
993 | lookup_write = write && !force; |
994 | spin_lock(&mm->page_table_lock); |
995 | } |
996 | if (pages) { |
997 | pages[i] = get_page_map(map); |
998 | if (!pages[i]) { |
999 | spin_unlock(&mm->page_table_lock); |
1000 | while (i--) |
1001 | page_cache_release(pages[i]); |
1002 | i = -EFAULT; |
1003 | goto out; |
1004 | } |
1005 | flush_dcache_page(pages[i]); |
1006 | if (!PageReserved(pages[i])) |
1007 | page_cache_get(pages[i]); |
1008 | } |
1009 | if (vmas) |
1010 | vmas[i] = vma; |
1011 | i++; |
1012 | start += PAGE_SIZE; |
1013 | len--; |
1014 | } while(len && start < vma->vm_end); |
1015 | spin_unlock(&mm->page_table_lock); |
1016 | } while(len); |
1017 | out: |
1018 | return i; |
1019 | } |
1020 | |
1021 | EXPORT_SYMBOL(get_user_pages); |
1022 | |
1023 | static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
1024 | unsigned long addr, unsigned long end, pgprot_t prot) |
1025 | { |
1026 | pte_t *pte; |
1027 | |
1028 | pte = pte_alloc_map(mm, pmd, addr); |
1029 | if (!pte) |
1030 | return -ENOMEM; |
1031 | do { |
1032 | pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(addr), prot)); |
1033 | BUG_ON(!pte_none(*pte)); |
1034 | set_pte_at(mm, addr, pte, zero_pte); |
1035 | } while (pte++, addr += PAGE_SIZE, addr != end); |
1036 | pte_unmap(pte - 1); |
1037 | return 0; |
1038 | } |
1039 | |
1040 | static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, |
1041 | unsigned long addr, unsigned long end, pgprot_t prot) |
1042 | { |
1043 | pmd_t *pmd; |
1044 | unsigned long next; |
1045 | |
1046 | pmd = pmd_alloc(mm, pud, addr); |
1047 | if (!pmd) |
1048 | return -ENOMEM; |
1049 | do { |
1050 | next = pmd_addr_end(addr, end); |
1051 | if (zeromap_pte_range(mm, pmd, addr, next, prot)) |
1052 | return -ENOMEM; |
1053 | } while (pmd++, addr = next, addr != end); |
1054 | return 0; |
1055 | } |
1056 | |
1057 | static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, |
1058 | unsigned long addr, unsigned long end, pgprot_t prot) |
1059 | { |
1060 | pud_t *pud; |
1061 | unsigned long next; |
1062 | |
1063 | pud = pud_alloc(mm, pgd, addr); |
1064 | if (!pud) |
1065 | return -ENOMEM; |
1066 | do { |
1067 | next = pud_addr_end(addr, end); |
1068 | if (zeromap_pmd_range(mm, pud, addr, next, prot)) |
1069 | return -ENOMEM; |
1070 | } while (pud++, addr = next, addr != end); |
1071 | return 0; |
1072 | } |
1073 | |
1074 | int zeromap_page_range(struct vm_area_struct *vma, |
1075 | unsigned long addr, unsigned long size, pgprot_t prot) |
1076 | { |
1077 | pgd_t *pgd; |
1078 | unsigned long next; |
1079 | unsigned long end = addr + PAGE_ALIGN(size); |
1080 | struct mm_struct *mm = vma->vm_mm; |
1081 | int err; |
1082 | |
1083 | BUG_ON(addr >= end); |
1084 | pgd = pgd_offset(mm, addr); |
1085 | flush_cache_range(vma, addr, end); |
1086 | spin_lock(&mm->page_table_lock); |
1087 | do { |
1088 | next = pgd_addr_end(addr, end); |
1089 | err = zeromap_pud_range(mm, pgd, addr, next, prot); |
1090 | if (err) |
1091 | break; |
1092 | } while (pgd++, addr = next, addr != end); |
1093 | spin_unlock(&mm->page_table_lock); |
1094 | return err; |
1095 | } |
1096 | |
1097 | /* |
1098 | * maps a range of physical memory into the requested pages. the old |
1099 | * mappings are removed. any references to nonexistent pages results |
1100 | * in null mappings (currently treated as "copy-on-access") |
1101 | */ |
1102 | static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
1103 | unsigned long addr, unsigned long end, |
1104 | unsigned long pfn, pgprot_t prot) |
1105 | { |
1106 | pte_t *pte; |
1107 | |
1108 | pte = pte_alloc_map(mm, pmd, addr); |
1109 | if (!pte) |
1110 | return -ENOMEM; |
1111 | do { |
1112 | BUG_ON(!pte_none(*pte)); |
1113 | if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn))) |
1114 | set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); |
1115 | pfn++; |
1116 | } while (pte++, addr += PAGE_SIZE, addr != end); |
1117 | pte_unmap(pte - 1); |
1118 | return 0; |
1119 | } |
1120 | |
1121 | static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, |
1122 | unsigned long addr, unsigned long end, |
1123 | unsigned long pfn, pgprot_t prot) |
1124 | { |
1125 | pmd_t *pmd; |
1126 | unsigned long next; |
1127 | |
1128 | pfn -= addr >> PAGE_SHIFT; |
1129 | pmd = pmd_alloc(mm, pud, addr); |
1130 | if (!pmd) |
1131 | return -ENOMEM; |
1132 | do { |
1133 | next = pmd_addr_end(addr, end); |
1134 | if (remap_pte_range(mm, pmd, addr, next, |
1135 | pfn + (addr >> PAGE_SHIFT), prot)) |
1136 | return -ENOMEM; |
1137 | } while (pmd++, addr = next, addr != end); |
1138 | return 0; |
1139 | } |
1140 | |
1141 | static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, |
1142 | unsigned long addr, unsigned long end, |
1143 | unsigned long pfn, pgprot_t prot) |
1144 | { |
1145 | pud_t *pud; |
1146 | unsigned long next; |
1147 | |
1148 | pfn -= addr >> PAGE_SHIFT; |
1149 | pud = pud_alloc(mm, pgd, addr); |
1150 | if (!pud) |
1151 | return -ENOMEM; |
1152 | do { |
1153 | next = pud_addr_end(addr, end); |
1154 | if (remap_pmd_range(mm, pud, addr, next, |
1155 | pfn + (addr >> PAGE_SHIFT), prot)) |
1156 | return -ENOMEM; |
1157 | } while (pud++, addr = next, addr != end); |
1158 | return 0; |
1159 | } |
1160 | |
1161 | /* Note: this is only safe if the mm semaphore is held when called. */ |
1162 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
1163 | unsigned long pfn, unsigned long size, pgprot_t prot) |
1164 | { |
1165 | pgd_t *pgd; |
1166 | unsigned long next; |
1167 | unsigned long end = addr + PAGE_ALIGN(size); |
1168 | struct mm_struct *mm = vma->vm_mm; |
1169 | int err; |
1170 | |
1171 | /* |
1172 | * Physically remapped pages are special. Tell the |
1173 | * rest of the world about it: |
1174 | * VM_IO tells people not to look at these pages |
1175 | * (accesses can have side effects). |
1176 | * VM_RESERVED tells swapout not to try to touch |
1177 | * this region. |
1178 | */ |
1179 | vma->vm_flags |= VM_IO | VM_RESERVED; |
1180 | |
1181 | BUG_ON(addr >= end); |
1182 | pfn -= addr >> PAGE_SHIFT; |
1183 | pgd = pgd_offset(mm, addr); |
1184 | flush_cache_range(vma, addr, end); |
1185 | spin_lock(&mm->page_table_lock); |
1186 | do { |
1187 | next = pgd_addr_end(addr, end); |
1188 | err = remap_pud_range(mm, pgd, addr, next, |
1189 | pfn + (addr >> PAGE_SHIFT), prot); |
1190 | if (err) |
1191 | break; |
1192 | } while (pgd++, addr = next, addr != end); |
1193 | spin_unlock(&mm->page_table_lock); |
1194 | return err; |
1195 | } |
1196 | EXPORT_SYMBOL(remap_pfn_range); |
1197 | |
1198 | /* |
1199 | * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when |
1200 | * servicing faults for write access. In the normal case, do always want |
1201 | * pte_mkwrite. But get_user_pages can cause write faults for mappings |
1202 | * that do not have writing enabled, when used by access_process_vm. |
1203 | */ |
1204 | static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) |
1205 | { |
1206 | if (likely(vma->vm_flags & VM_WRITE)) |
1207 | pte = pte_mkwrite(pte); |
1208 | return pte; |
1209 | } |
1210 | |
1211 | /* |
1212 | * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock |
1213 | */ |
1214 | static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address, |
1215 | pte_t *page_table) |
1216 | { |
1217 | pte_t entry; |
1218 | |
1219 | entry = maybe_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot)), |
1220 | vma); |
1221 | ptep_establish(vma, address, page_table, entry); |
1222 | update_mmu_cache(vma, address, entry); |
1223 | lazy_mmu_prot_update(entry); |
1224 | } |
1225 | |
1226 | /* |
1227 | * This routine handles present pages, when users try to write |
1228 | * to a shared page. It is done by copying the page to a new address |
1229 | * and decrementing the shared-page counter for the old page. |
1230 | * |
1231 | * Goto-purists beware: the only reason for goto's here is that it results |
1232 | * in better assembly code.. The "default" path will see no jumps at all. |
1233 | * |
1234 | * Note that this routine assumes that the protection checks have been |
1235 | * done by the caller (the low-level page fault routine in most cases). |
1236 | * Thus we can safely just mark it writable once we've done any necessary |
1237 | * COW. |
1238 | * |
1239 | * We also mark the page dirty at this point even though the page will |
1240 | * change only once the write actually happens. This avoids a few races, |
1241 | * and potentially makes it more efficient. |
1242 | * |
1243 | * We hold the mm semaphore and the page_table_lock on entry and exit |
1244 | * with the page_table_lock released. |
1245 | */ |
1246 | static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma, |
1247 | unsigned long address, pte_t *page_table, pmd_t *pmd, pte_t pte) |
1248 | { |
1249 | struct page *old_page, *new_page; |
1250 | unsigned long pfn = pte_pfn(pte); |
1251 | pte_t entry; |
1252 | |
1253 | if (unlikely(!pfn_valid(pfn))) { |
1254 | /* |
1255 | * This should really halt the system so it can be debugged or |
1256 | * at least the kernel stops what it's doing before it corrupts |
1257 | * data, but for the moment just pretend this is OOM. |
1258 | */ |
1259 | pte_unmap(page_table); |
1260 | printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n", |
1261 | address); |
1262 | spin_unlock(&mm->page_table_lock); |
1263 | return VM_FAULT_OOM; |
1264 | } |
1265 | old_page = pfn_to_page(pfn); |
1266 | |
1267 | if (!TestSetPageLocked(old_page)) { |
1268 | int reuse = can_share_swap_page(old_page); |
1269 | unlock_page(old_page); |
1270 | if (reuse) { |
1271 | flush_cache_page(vma, address, pfn); |
1272 | entry = maybe_mkwrite(pte_mkyoung(pte_mkdirty(pte)), |
1273 | vma); |
1274 | ptep_set_access_flags(vma, address, page_table, entry, 1); |
1275 | update_mmu_cache(vma, address, entry); |
1276 | lazy_mmu_prot_update(entry); |
1277 | pte_unmap(page_table); |
1278 | spin_unlock(&mm->page_table_lock); |
1279 | return VM_FAULT_MINOR; |
1280 | } |
1281 | } |
1282 | pte_unmap(page_table); |
1283 | |
1284 | /* |
1285 | * Ok, we need to copy. Oh, well.. |
1286 | */ |
1287 | if (!PageReserved(old_page)) |
1288 | page_cache_get(old_page); |
1289 | spin_unlock(&mm->page_table_lock); |
1290 | |
1291 | if (unlikely(anon_vma_prepare(vma))) |
1292 | goto no_new_page; |
1293 | if (old_page == ZERO_PAGE(address)) { |
1294 | new_page = alloc_zeroed_user_highpage(vma, address); |
1295 | if (!new_page) |
1296 | goto no_new_page; |
1297 | } else { |
1298 | new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); |
1299 | if (!new_page) |
1300 | goto no_new_page; |
1301 | copy_user_highpage(new_page, old_page, address); |
1302 | } |
1303 | /* |
1304 | * Re-check the pte - we dropped the lock |
1305 | */ |
1306 | spin_lock(&mm->page_table_lock); |
1307 | page_table = pte_offset_map(pmd, address); |
1308 | if (likely(pte_same(*page_table, pte))) { |
1309 | if (PageAnon(old_page)) |
1310 | dec_mm_counter(mm, anon_rss); |
1311 | if (PageReserved(old_page)) |
1312 | inc_mm_counter(mm, rss); |
1313 | else |
1314 | page_remove_rmap(old_page); |
1315 | flush_cache_page(vma, address, pfn); |
1316 | break_cow(vma, new_page, address, page_table); |
1317 | lru_cache_add_active(new_page); |
1318 | page_add_anon_rmap(new_page, vma, address); |
1319 | |
1320 | /* Free the old page.. */ |
1321 | new_page = old_page; |
1322 | } |
1323 | pte_unmap(page_table); |
1324 | page_cache_release(new_page); |
1325 | page_cache_release(old_page); |
1326 | spin_unlock(&mm->page_table_lock); |
1327 | return VM_FAULT_MINOR; |
1328 | |
1329 | no_new_page: |
1330 | page_cache_release(old_page); |
1331 | return VM_FAULT_OOM; |
1332 | } |
1333 | |
1334 | /* |
1335 | * Helper functions for unmap_mapping_range(). |
1336 | * |
1337 | * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ |
1338 | * |
1339 | * We have to restart searching the prio_tree whenever we drop the lock, |
1340 | * since the iterator is only valid while the lock is held, and anyway |
1341 | * a later vma might be split and reinserted earlier while lock dropped. |
1342 | * |
1343 | * The list of nonlinear vmas could be handled more efficiently, using |
1344 | * a placeholder, but handle it in the same way until a need is shown. |
1345 | * It is important to search the prio_tree before nonlinear list: a vma |
1346 | * may become nonlinear and be shifted from prio_tree to nonlinear list |
1347 | * while the lock is dropped; but never shifted from list to prio_tree. |
1348 | * |
1349 | * In order to make forward progress despite restarting the search, |
1350 | * vm_truncate_count is used to mark a vma as now dealt with, so we can |
1351 | * quickly skip it next time around. Since the prio_tree search only |
1352 | * shows us those vmas affected by unmapping the range in question, we |
1353 | * can't efficiently keep all vmas in step with mapping->truncate_count: |
1354 | * so instead reset them all whenever it wraps back to 0 (then go to 1). |
1355 | * mapping->truncate_count and vma->vm_truncate_count are protected by |
1356 | * i_mmap_lock. |
1357 | * |
1358 | * In order to make forward progress despite repeatedly restarting some |
1359 | * large vma, note the restart_addr from unmap_vmas when it breaks out: |
1360 | * and restart from that address when we reach that vma again. It might |
1361 | * have been split or merged, shrunk or extended, but never shifted: so |
1362 | * restart_addr remains valid so long as it remains in the vma's range. |
1363 | * unmap_mapping_range forces truncate_count to leap over page-aligned |
1364 | * values so we can save vma's restart_addr in its truncate_count field. |
1365 | */ |
1366 | #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) |
1367 | |
1368 | static void reset_vma_truncate_counts(struct address_space *mapping) |
1369 | { |
1370 | struct vm_area_struct *vma; |
1371 | struct prio_tree_iter iter; |
1372 | |
1373 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) |
1374 | vma->vm_truncate_count = 0; |
1375 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
1376 | vma->vm_truncate_count = 0; |
1377 | } |
1378 | |
1379 | static int unmap_mapping_range_vma(struct vm_area_struct *vma, |
1380 | unsigned long start_addr, unsigned long end_addr, |
1381 | struct zap_details *details) |
1382 | { |
1383 | unsigned long restart_addr; |
1384 | int need_break; |
1385 | |
1386 | again: |
1387 | restart_addr = vma->vm_truncate_count; |
1388 | if (is_restart_addr(restart_addr) && start_addr < restart_addr) { |
1389 | start_addr = restart_addr; |
1390 | if (start_addr >= end_addr) { |
1391 | /* Top of vma has been split off since last time */ |
1392 | vma->vm_truncate_count = details->truncate_count; |
1393 | return 0; |
1394 | } |
1395 | } |
1396 | |
1397 | restart_addr = zap_page_range(vma, start_addr, |
1398 | end_addr - start_addr, details); |
1399 | |
1400 | /* |
1401 | * We cannot rely on the break test in unmap_vmas: |
1402 | * on the one hand, we don't want to restart our loop |
1403 | * just because that broke out for the page_table_lock; |
1404 | * on the other hand, it does no test when vma is small. |
1405 | */ |
1406 | need_break = need_resched() || |
1407 | need_lockbreak(details->i_mmap_lock); |
1408 | |
1409 | if (restart_addr >= end_addr) { |
1410 | /* We have now completed this vma: mark it so */ |
1411 | vma->vm_truncate_count = details->truncate_count; |
1412 | if (!need_break) |
1413 | return 0; |
1414 | } else { |
1415 | /* Note restart_addr in vma's truncate_count field */ |
1416 | vma->vm_truncate_count = restart_addr; |
1417 | if (!need_break) |
1418 | goto again; |
1419 | } |
1420 | |
1421 | spin_unlock(details->i_mmap_lock); |
1422 | cond_resched(); |
1423 | spin_lock(details->i_mmap_lock); |
1424 | return -EINTR; |
1425 | } |
1426 | |
1427 | static inline void unmap_mapping_range_tree(struct prio_tree_root *root, |
1428 | struct zap_details *details) |
1429 | { |
1430 | struct vm_area_struct *vma; |
1431 | struct prio_tree_iter iter; |
1432 | pgoff_t vba, vea, zba, zea; |
1433 | |
1434 | restart: |
1435 | vma_prio_tree_foreach(vma, &iter, root, |
1436 | details->first_index, details->last_index) { |
1437 | /* Skip quickly over those we have already dealt with */ |
1438 | if (vma->vm_truncate_count == details->truncate_count) |
1439 | continue; |
1440 | |
1441 | vba = vma->vm_pgoff; |
1442 | vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; |
1443 | /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ |
1444 | zba = details->first_index; |
1445 | if (zba < vba) |
1446 | zba = vba; |
1447 | zea = details->last_index; |
1448 | if (zea > vea) |
1449 | zea = vea; |
1450 | |
1451 | if (unmap_mapping_range_vma(vma, |
1452 | ((zba - vba) << PAGE_SHIFT) + vma->vm_start, |
1453 | ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, |
1454 | details) < 0) |
1455 | goto restart; |
1456 | } |
1457 | } |
1458 | |
1459 | static inline void unmap_mapping_range_list(struct list_head *head, |
1460 | struct zap_details *details) |
1461 | { |
1462 | struct vm_area_struct *vma; |
1463 | |
1464 | /* |
1465 | * In nonlinear VMAs there is no correspondence between virtual address |
1466 | * offset and file offset. So we must perform an exhaustive search |
1467 | * across *all* the pages in each nonlinear VMA, not just the pages |
1468 | * whose virtual address lies outside the file truncation point. |
1469 | */ |
1470 | restart: |
1471 | list_for_each_entry(vma, head, shared.vm_set.list) { |
1472 | /* Skip quickly over those we have already dealt with */ |
1473 | if (vma->vm_truncate_count == details->truncate_count) |
1474 | continue; |
1475 | details->nonlinear_vma = vma; |
1476 | if (unmap_mapping_range_vma(vma, vma->vm_start, |
1477 | vma->vm_end, details) < 0) |
1478 | goto restart; |
1479 | } |
1480 | } |
1481 | |
1482 | /** |
1483 | * unmap_mapping_range - unmap the portion of all mmaps |
1484 | * in the specified address_space corresponding to the specified |
1485 | * page range in the underlying file. |
1486 | * @address_space: the address space containing mmaps to be unmapped. |
1487 | * @holebegin: byte in first page to unmap, relative to the start of |
1488 | * the underlying file. This will be rounded down to a PAGE_SIZE |
1489 | * boundary. Note that this is different from vmtruncate(), which |
1490 | * must keep the partial page. In contrast, we must get rid of |
1491 | * partial pages. |
1492 | * @holelen: size of prospective hole in bytes. This will be rounded |
1493 | * up to a PAGE_SIZE boundary. A holelen of zero truncates to the |
1494 | * end of the file. |
1495 | * @even_cows: 1 when truncating a file, unmap even private COWed pages; |
1496 | * but 0 when invalidating pagecache, don't throw away private data. |
1497 | */ |
1498 | void unmap_mapping_range(struct address_space *mapping, |
1499 | loff_t const holebegin, loff_t const holelen, int even_cows) |
1500 | { |
1501 | struct zap_details details; |
1502 | pgoff_t hba = holebegin >> PAGE_SHIFT; |
1503 | pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1504 | |
1505 | /* Check for overflow. */ |
1506 | if (sizeof(holelen) > sizeof(hlen)) { |
1507 | long long holeend = |
1508 | (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1509 | if (holeend & ~(long long)ULONG_MAX) |
1510 | hlen = ULONG_MAX - hba + 1; |
1511 | } |
1512 | |
1513 | details.check_mapping = even_cows? NULL: mapping; |
1514 | details.nonlinear_vma = NULL; |
1515 | details.first_index = hba; |
1516 | details.last_index = hba + hlen - 1; |
1517 | if (details.last_index < details.first_index) |
1518 | details.last_index = ULONG_MAX; |
1519 | details.i_mmap_lock = &mapping->i_mmap_lock; |
1520 | |
1521 | spin_lock(&mapping->i_mmap_lock); |
1522 | |
1523 | /* serialize i_size write against truncate_count write */ |
1524 | smp_wmb(); |
1525 | /* Protect against page faults, and endless unmapping loops */ |
1526 | mapping->truncate_count++; |
1527 | /* |
1528 | * For archs where spin_lock has inclusive semantics like ia64 |
1529 | * this smp_mb() will prevent to read pagetable contents |
1530 | * before the truncate_count increment is visible to |
1531 | * other cpus. |
1532 | */ |
1533 | smp_mb(); |
1534 | if (unlikely(is_restart_addr(mapping->truncate_count))) { |
1535 | if (mapping->truncate_count == 0) |
1536 | reset_vma_truncate_counts(mapping); |
1537 | mapping->truncate_count++; |
1538 | } |
1539 | details.truncate_count = mapping->truncate_count; |
1540 | |
1541 | if (unlikely(!prio_tree_empty(&mapping->i_mmap))) |
1542 | unmap_mapping_range_tree(&mapping->i_mmap, &details); |
1543 | if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) |
1544 | unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); |
1545 | spin_unlock(&mapping->i_mmap_lock); |
1546 | } |
1547 | EXPORT_SYMBOL(unmap_mapping_range); |
1548 | |
1549 | /* |
1550 | * Handle all mappings that got truncated by a "truncate()" |
1551 | * system call. |
1552 | * |
1553 | * NOTE! We have to be ready to update the memory sharing |
1554 | * between the file and the memory map for a potential last |
1555 | * incomplete page. Ugly, but necessary. |
1556 | */ |
1557 | int vmtruncate(struct inode * inode, loff_t offset) |
1558 | { |
1559 | struct address_space *mapping = inode->i_mapping; |
1560 | unsigned long limit; |
1561 | |
1562 | if (inode->i_size < offset) |
1563 | goto do_expand; |
1564 | /* |
1565 | * truncation of in-use swapfiles is disallowed - it would cause |
1566 | * subsequent swapout to scribble on the now-freed blocks. |
1567 | */ |
1568 | if (IS_SWAPFILE(inode)) |
1569 | goto out_busy; |
1570 | i_size_write(inode, offset); |
1571 | unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); |
1572 | truncate_inode_pages(mapping, offset); |
1573 | goto out_truncate; |
1574 | |
1575 | do_expand: |
1576 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; |
1577 | if (limit != RLIM_INFINITY && offset > limit) |
1578 | goto out_sig; |
1579 | if (offset > inode->i_sb->s_maxbytes) |
1580 | goto out_big; |
1581 | i_size_write(inode, offset); |
1582 | |
1583 | out_truncate: |
1584 | if (inode->i_op && inode->i_op->truncate) |
1585 | inode->i_op->truncate(inode); |
1586 | return 0; |
1587 | out_sig: |
1588 | send_sig(SIGXFSZ, current, 0); |
1589 | out_big: |
1590 | return -EFBIG; |
1591 | out_busy: |
1592 | return -ETXTBSY; |
1593 | } |
1594 | |
1595 | EXPORT_SYMBOL(vmtruncate); |
1596 | |
1597 | /* |
1598 | * Primitive swap readahead code. We simply read an aligned block of |
1599 | * (1 << page_cluster) entries in the swap area. This method is chosen |
1600 | * because it doesn't cost us any seek time. We also make sure to queue |
1601 | * the 'original' request together with the readahead ones... |
1602 | * |
1603 | * This has been extended to use the NUMA policies from the mm triggering |
1604 | * the readahead. |
1605 | * |
1606 | * Caller must hold down_read on the vma->vm_mm if vma is not NULL. |
1607 | */ |
1608 | void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) |
1609 | { |
1610 | #ifdef CONFIG_NUMA |
1611 | struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; |
1612 | #endif |
1613 | int i, num; |
1614 | struct page *new_page; |
1615 | unsigned long offset; |
1616 | |
1617 | /* |
1618 | * Get the number of handles we should do readahead io to. |
1619 | */ |
1620 | num = valid_swaphandles(entry, &offset); |
1621 | for (i = 0; i < num; offset++, i++) { |
1622 | /* Ok, do the async read-ahead now */ |
1623 | new_page = read_swap_cache_async(swp_entry(swp_type(entry), |
1624 | offset), vma, addr); |
1625 | if (!new_page) |
1626 | break; |
1627 | page_cache_release(new_page); |
1628 | #ifdef CONFIG_NUMA |
1629 | /* |
1630 | * Find the next applicable VMA for the NUMA policy. |
1631 | */ |
1632 | addr += PAGE_SIZE; |
1633 | if (addr == 0) |
1634 | vma = NULL; |
1635 | if (vma) { |
1636 | if (addr >= vma->vm_end) { |
1637 | vma = next_vma; |
1638 | next_vma = vma ? vma->vm_next : NULL; |
1639 | } |
1640 | if (vma && addr < vma->vm_start) |
1641 | vma = NULL; |
1642 | } else { |
1643 | if (next_vma && addr >= next_vma->vm_start) { |
1644 | vma = next_vma; |
1645 | next_vma = vma->vm_next; |
1646 | } |
1647 | } |
1648 | #endif |
1649 | } |
1650 | lru_add_drain(); /* Push any new pages onto the LRU now */ |
1651 | } |
1652 | |
1653 | /* |
1654 | * We hold the mm semaphore and the page_table_lock on entry and |
1655 | * should release the pagetable lock on exit.. |
1656 | */ |
1657 | static int do_swap_page(struct mm_struct * mm, |
1658 | struct vm_area_struct * vma, unsigned long address, |
1659 | pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access) |
1660 | { |
1661 | struct page *page; |
1662 | swp_entry_t entry = pte_to_swp_entry(orig_pte); |
1663 | pte_t pte; |
1664 | int ret = VM_FAULT_MINOR; |
1665 | |
1666 | pte_unmap(page_table); |
1667 | spin_unlock(&mm->page_table_lock); |
1668 | page = lookup_swap_cache(entry); |
1669 | if (!page) { |
1670 | swapin_readahead(entry, address, vma); |
1671 | page = read_swap_cache_async(entry, vma, address); |
1672 | if (!page) { |
1673 | /* |
1674 | * Back out if somebody else faulted in this pte while |
1675 | * we released the page table lock. |
1676 | */ |
1677 | spin_lock(&mm->page_table_lock); |
1678 | page_table = pte_offset_map(pmd, address); |
1679 | if (likely(pte_same(*page_table, orig_pte))) |
1680 | ret = VM_FAULT_OOM; |
1681 | else |
1682 | ret = VM_FAULT_MINOR; |
1683 | pte_unmap(page_table); |
1684 | spin_unlock(&mm->page_table_lock); |
1685 | goto out; |
1686 | } |
1687 | |
1688 | /* Had to read the page from swap area: Major fault */ |
1689 | ret = VM_FAULT_MAJOR; |
1690 | inc_page_state(pgmajfault); |
1691 | grab_swap_token(); |
1692 | } |
1693 | |
1694 | mark_page_accessed(page); |
1695 | lock_page(page); |
1696 | |
1697 | /* |
1698 | * Back out if somebody else faulted in this pte while we |
1699 | * released the page table lock. |
1700 | */ |
1701 | spin_lock(&mm->page_table_lock); |
1702 | page_table = pte_offset_map(pmd, address); |
1703 | if (unlikely(!pte_same(*page_table, orig_pte))) { |
1704 | ret = VM_FAULT_MINOR; |
1705 | goto out_nomap; |
1706 | } |
1707 | |
1708 | if (unlikely(!PageUptodate(page))) { |
1709 | ret = VM_FAULT_SIGBUS; |
1710 | goto out_nomap; |
1711 | } |
1712 | |
1713 | /* The page isn't present yet, go ahead with the fault. */ |
1714 | |
1715 | swap_free(entry); |
1716 | if (vm_swap_full()) |
1717 | remove_exclusive_swap_page(page); |
1718 | |
1719 | inc_mm_counter(mm, rss); |
1720 | pte = mk_pte(page, vma->vm_page_prot); |
1721 | if (write_access && can_share_swap_page(page)) { |
1722 | pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
1723 | write_access = 0; |
1724 | } |
1725 | unlock_page(page); |
1726 | |
1727 | flush_icache_page(vma, page); |
1728 | set_pte_at(mm, address, page_table, pte); |
1729 | page_add_anon_rmap(page, vma, address); |
1730 | |
1731 | if (write_access) { |
1732 | if (do_wp_page(mm, vma, address, |
1733 | page_table, pmd, pte) == VM_FAULT_OOM) |
1734 | ret = VM_FAULT_OOM; |
1735 | goto out; |
1736 | } |
1737 | |
1738 | /* No need to invalidate - it was non-present before */ |
1739 | update_mmu_cache(vma, address, pte); |
1740 | lazy_mmu_prot_update(pte); |
1741 | pte_unmap(page_table); |
1742 | spin_unlock(&mm->page_table_lock); |
1743 | out: |
1744 | return ret; |
1745 | out_nomap: |
1746 | pte_unmap(page_table); |
1747 | spin_unlock(&mm->page_table_lock); |
1748 | unlock_page(page); |
1749 | page_cache_release(page); |
1750 | goto out; |
1751 | } |
1752 | |
1753 | /* |
1754 | * We are called with the MM semaphore and page_table_lock |
1755 | * spinlock held to protect against concurrent faults in |
1756 | * multithreaded programs. |
1757 | */ |
1758 | static int |
1759 | do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1760 | pte_t *page_table, pmd_t *pmd, int write_access, |
1761 | unsigned long addr) |
1762 | { |
1763 | pte_t entry; |
1764 | struct page * page = ZERO_PAGE(addr); |
1765 | |
1766 | /* Read-only mapping of ZERO_PAGE. */ |
1767 | entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot)); |
1768 | |
1769 | /* ..except if it's a write access */ |
1770 | if (write_access) { |
1771 | /* Allocate our own private page. */ |
1772 | pte_unmap(page_table); |
1773 | spin_unlock(&mm->page_table_lock); |
1774 | |
1775 | if (unlikely(anon_vma_prepare(vma))) |
1776 | goto no_mem; |
1777 | page = alloc_zeroed_user_highpage(vma, addr); |
1778 | if (!page) |
1779 | goto no_mem; |
1780 | |
1781 | spin_lock(&mm->page_table_lock); |
1782 | page_table = pte_offset_map(pmd, addr); |
1783 | |
1784 | if (!pte_none(*page_table)) { |
1785 | pte_unmap(page_table); |
1786 | page_cache_release(page); |
1787 | spin_unlock(&mm->page_table_lock); |
1788 | goto out; |
1789 | } |
1790 | inc_mm_counter(mm, rss); |
1791 | entry = maybe_mkwrite(pte_mkdirty(mk_pte(page, |
1792 | vma->vm_page_prot)), |
1793 | vma); |
1794 | lru_cache_add_active(page); |
1795 | SetPageReferenced(page); |
1796 | page_add_anon_rmap(page, vma, addr); |
1797 | } |
1798 | |
1799 | set_pte_at(mm, addr, page_table, entry); |
1800 | pte_unmap(page_table); |
1801 | |
1802 | /* No need to invalidate - it was non-present before */ |
1803 | update_mmu_cache(vma, addr, entry); |
1804 | lazy_mmu_prot_update(entry); |
1805 | spin_unlock(&mm->page_table_lock); |
1806 | out: |
1807 | return VM_FAULT_MINOR; |
1808 | no_mem: |
1809 | return VM_FAULT_OOM; |
1810 | } |
1811 | |
1812 | /* |
1813 | * do_no_page() tries to create a new page mapping. It aggressively |
1814 | * tries to share with existing pages, but makes a separate copy if |
1815 | * the "write_access" parameter is true in order to avoid the next |
1816 | * page fault. |
1817 | * |
1818 | * As this is called only for pages that do not currently exist, we |
1819 | * do not need to flush old virtual caches or the TLB. |
1820 | * |
1821 | * This is called with the MM semaphore held and the page table |
1822 | * spinlock held. Exit with the spinlock released. |
1823 | */ |
1824 | static int |
1825 | do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, |
1826 | unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd) |
1827 | { |
1828 | struct page * new_page; |
1829 | struct address_space *mapping = NULL; |
1830 | pte_t entry; |
1831 | unsigned int sequence = 0; |
1832 | int ret = VM_FAULT_MINOR; |
1833 | int anon = 0; |
1834 | |
1835 | if (!vma->vm_ops || !vma->vm_ops->nopage) |
1836 | return do_anonymous_page(mm, vma, page_table, |
1837 | pmd, write_access, address); |
1838 | pte_unmap(page_table); |
1839 | spin_unlock(&mm->page_table_lock); |
1840 | |
1841 | if (vma->vm_file) { |
1842 | mapping = vma->vm_file->f_mapping; |
1843 | sequence = mapping->truncate_count; |
1844 | smp_rmb(); /* serializes i_size against truncate_count */ |
1845 | } |
1846 | retry: |
1847 | cond_resched(); |
1848 | new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); |
1849 | /* |
1850 | * No smp_rmb is needed here as long as there's a full |
1851 | * spin_lock/unlock sequence inside the ->nopage callback |
1852 | * (for the pagecache lookup) that acts as an implicit |
1853 | * smp_mb() and prevents the i_size read to happen |
1854 | * after the next truncate_count read. |
1855 | */ |
1856 | |
1857 | /* no page was available -- either SIGBUS or OOM */ |
1858 | if (new_page == NOPAGE_SIGBUS) |
1859 | return VM_FAULT_SIGBUS; |
1860 | if (new_page == NOPAGE_OOM) |
1861 | return VM_FAULT_OOM; |
1862 | |
1863 | /* |
1864 | * Should we do an early C-O-W break? |
1865 | */ |
1866 | if (write_access && !(vma->vm_flags & VM_SHARED)) { |
1867 | struct page *page; |
1868 | |
1869 | if (unlikely(anon_vma_prepare(vma))) |
1870 | goto oom; |
1871 | page = alloc_page_vma(GFP_HIGHUSER, vma, address); |
1872 | if (!page) |
1873 | goto oom; |
1874 | copy_user_highpage(page, new_page, address); |
1875 | page_cache_release(new_page); |
1876 | new_page = page; |
1877 | anon = 1; |
1878 | } |
1879 | |
1880 | spin_lock(&mm->page_table_lock); |
1881 | /* |
1882 | * For a file-backed vma, someone could have truncated or otherwise |
1883 | * invalidated this page. If unmap_mapping_range got called, |
1884 | * retry getting the page. |
1885 | */ |
1886 | if (mapping && unlikely(sequence != mapping->truncate_count)) { |
1887 | sequence = mapping->truncate_count; |
1888 | spin_unlock(&mm->page_table_lock); |
1889 | page_cache_release(new_page); |
1890 | goto retry; |
1891 | } |
1892 | page_table = pte_offset_map(pmd, address); |
1893 | |
1894 | /* |
1895 | * This silly early PAGE_DIRTY setting removes a race |
1896 | * due to the bad i386 page protection. But it's valid |
1897 | * for other architectures too. |
1898 | * |
1899 | * Note that if write_access is true, we either now have |
1900 | * an exclusive copy of the page, or this is a shared mapping, |
1901 | * so we can make it writable and dirty to avoid having to |
1902 | * handle that later. |
1903 | */ |
1904 | /* Only go through if we didn't race with anybody else... */ |
1905 | if (pte_none(*page_table)) { |
1906 | if (!PageReserved(new_page)) |
1907 | inc_mm_counter(mm, rss); |
1908 | |
1909 | flush_icache_page(vma, new_page); |
1910 | entry = mk_pte(new_page, vma->vm_page_prot); |
1911 | if (write_access) |
1912 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
1913 | set_pte_at(mm, address, page_table, entry); |
1914 | if (anon) { |
1915 | lru_cache_add_active(new_page); |
1916 | page_add_anon_rmap(new_page, vma, address); |
1917 | } else |
1918 | page_add_file_rmap(new_page); |
1919 | pte_unmap(page_table); |
1920 | } else { |
1921 | /* One of our sibling threads was faster, back out. */ |
1922 | pte_unmap(page_table); |
1923 | page_cache_release(new_page); |
1924 | spin_unlock(&mm->page_table_lock); |
1925 | goto out; |
1926 | } |
1927 | |
1928 | /* no need to invalidate: a not-present page shouldn't be cached */ |
1929 | update_mmu_cache(vma, address, entry); |
1930 | lazy_mmu_prot_update(entry); |
1931 | spin_unlock(&mm->page_table_lock); |
1932 | out: |
1933 | return ret; |
1934 | oom: |
1935 | page_cache_release(new_page); |
1936 | ret = VM_FAULT_OOM; |
1937 | goto out; |
1938 | } |
1939 | |
1940 | /* |
1941 | * Fault of a previously existing named mapping. Repopulate the pte |
1942 | * from the encoded file_pte if possible. This enables swappable |
1943 | * nonlinear vmas. |
1944 | */ |
1945 | static int do_file_page(struct mm_struct * mm, struct vm_area_struct * vma, |
1946 | unsigned long address, int write_access, pte_t *pte, pmd_t *pmd) |
1947 | { |
1948 | unsigned long pgoff; |
1949 | int err; |
1950 | |
1951 | BUG_ON(!vma->vm_ops || !vma->vm_ops->nopage); |
1952 | /* |
1953 | * Fall back to the linear mapping if the fs does not support |
1954 | * ->populate: |
1955 | */ |
1956 | if (!vma->vm_ops || !vma->vm_ops->populate || |
1957 | (write_access && !(vma->vm_flags & VM_SHARED))) { |
1958 | pte_clear(mm, address, pte); |
1959 | return do_no_page(mm, vma, address, write_access, pte, pmd); |
1960 | } |
1961 | |
1962 | pgoff = pte_to_pgoff(*pte); |
1963 | |
1964 | pte_unmap(pte); |
1965 | spin_unlock(&mm->page_table_lock); |
1966 | |
1967 | err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, vma->vm_page_prot, pgoff, 0); |
1968 | if (err == -ENOMEM) |
1969 | return VM_FAULT_OOM; |
1970 | if (err) |
1971 | return VM_FAULT_SIGBUS; |
1972 | return VM_FAULT_MAJOR; |
1973 | } |
1974 | |
1975 | /* |
1976 | * These routines also need to handle stuff like marking pages dirty |
1977 | * and/or accessed for architectures that don't do it in hardware (most |
1978 | * RISC architectures). The early dirtying is also good on the i386. |
1979 | * |
1980 | * There is also a hook called "update_mmu_cache()" that architectures |
1981 | * with external mmu caches can use to update those (ie the Sparc or |
1982 | * PowerPC hashed page tables that act as extended TLBs). |
1983 | * |
1984 | * Note the "page_table_lock". It is to protect against kswapd removing |
1985 | * pages from under us. Note that kswapd only ever _removes_ pages, never |
1986 | * adds them. As such, once we have noticed that the page is not present, |
1987 | * we can drop the lock early. |
1988 | * |
1989 | * The adding of pages is protected by the MM semaphore (which we hold), |
1990 | * so we don't need to worry about a page being suddenly been added into |
1991 | * our VM. |
1992 | * |
1993 | * We enter with the pagetable spinlock held, we are supposed to |
1994 | * release it when done. |
1995 | */ |
1996 | static inline int handle_pte_fault(struct mm_struct *mm, |
1997 | struct vm_area_struct * vma, unsigned long address, |
1998 | int write_access, pte_t *pte, pmd_t *pmd) |
1999 | { |
2000 | pte_t entry; |
2001 | |
2002 | entry = *pte; |
2003 | if (!pte_present(entry)) { |
2004 | /* |
2005 | * If it truly wasn't present, we know that kswapd |
2006 | * and the PTE updates will not touch it later. So |
2007 | * drop the lock. |
2008 | */ |
2009 | if (pte_none(entry)) |
2010 | return do_no_page(mm, vma, address, write_access, pte, pmd); |
2011 | if (pte_file(entry)) |
2012 | return do_file_page(mm, vma, address, write_access, pte, pmd); |
2013 | return do_swap_page(mm, vma, address, pte, pmd, entry, write_access); |
2014 | } |
2015 | |
2016 | if (write_access) { |
2017 | if (!pte_write(entry)) |
2018 | return do_wp_page(mm, vma, address, pte, pmd, entry); |
2019 | |
2020 | entry = pte_mkdirty(entry); |
2021 | } |
2022 | entry = pte_mkyoung(entry); |
2023 | ptep_set_access_flags(vma, address, pte, entry, write_access); |
2024 | update_mmu_cache(vma, address, entry); |
2025 | lazy_mmu_prot_update(entry); |
2026 | pte_unmap(pte); |
2027 | spin_unlock(&mm->page_table_lock); |
2028 | return VM_FAULT_MINOR; |
2029 | } |
2030 | |
2031 | /* |
2032 | * By the time we get here, we already hold the mm semaphore |
2033 | */ |
2034 | int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma, |
2035 | unsigned long address, int write_access) |
2036 | { |
2037 | pgd_t *pgd; |
2038 | pud_t *pud; |
2039 | pmd_t *pmd; |
2040 | pte_t *pte; |
2041 | |
2042 | __set_current_state(TASK_RUNNING); |
2043 | |
2044 | inc_page_state(pgfault); |
2045 | |
2046 | if (is_vm_hugetlb_page(vma)) |
2047 | return VM_FAULT_SIGBUS; /* mapping truncation does this. */ |
2048 | |
2049 | /* |
2050 | * We need the page table lock to synchronize with kswapd |
2051 | * and the SMP-safe atomic PTE updates. |
2052 | */ |
2053 | pgd = pgd_offset(mm, address); |
2054 | spin_lock(&mm->page_table_lock); |
2055 | |
2056 | pud = pud_alloc(mm, pgd, address); |
2057 | if (!pud) |
2058 | goto oom; |
2059 | |
2060 | pmd = pmd_alloc(mm, pud, address); |
2061 | if (!pmd) |
2062 | goto oom; |
2063 | |
2064 | pte = pte_alloc_map(mm, pmd, address); |
2065 | if (!pte) |
2066 | goto oom; |
2067 | |
2068 | return handle_pte_fault(mm, vma, address, write_access, pte, pmd); |
2069 | |
2070 | oom: |
2071 | spin_unlock(&mm->page_table_lock); |
2072 | return VM_FAULT_OOM; |
2073 | } |
2074 | |
2075 | #ifndef __PAGETABLE_PUD_FOLDED |
2076 | /* |
2077 | * Allocate page upper directory. |
2078 | * |
2079 | * We've already handled the fast-path in-line, and we own the |
2080 | * page table lock. |
2081 | */ |
2082 | pud_t fastcall *__pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) |
2083 | { |
2084 | pud_t *new; |
2085 | |
2086 | spin_unlock(&mm->page_table_lock); |
2087 | new = pud_alloc_one(mm, address); |
2088 | spin_lock(&mm->page_table_lock); |
2089 | if (!new) |
2090 | return NULL; |
2091 | |
2092 | /* |
2093 | * Because we dropped the lock, we should re-check the |
2094 | * entry, as somebody else could have populated it.. |
2095 | */ |
2096 | if (pgd_present(*pgd)) { |
2097 | pud_free(new); |
2098 | goto out; |
2099 | } |
2100 | pgd_populate(mm, pgd, new); |
2101 | out: |
2102 | return pud_offset(pgd, address); |
2103 | } |
2104 | #endif /* __PAGETABLE_PUD_FOLDED */ |
2105 | |
2106 | #ifndef __PAGETABLE_PMD_FOLDED |
2107 | /* |
2108 | * Allocate page middle directory. |
2109 | * |
2110 | * We've already handled the fast-path in-line, and we own the |
2111 | * page table lock. |
2112 | */ |
2113 | pmd_t fastcall *__pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) |
2114 | { |
2115 | pmd_t *new; |
2116 | |
2117 | spin_unlock(&mm->page_table_lock); |
2118 | new = pmd_alloc_one(mm, address); |
2119 | spin_lock(&mm->page_table_lock); |
2120 | if (!new) |
2121 | return NULL; |
2122 | |
2123 | /* |
2124 | * Because we dropped the lock, we should re-check the |
2125 | * entry, as somebody else could have populated it.. |
2126 | */ |
2127 | #ifndef __ARCH_HAS_4LEVEL_HACK |
2128 | if (pud_present(*pud)) { |
2129 | pmd_free(new); |
2130 | goto out; |
2131 | } |
2132 | pud_populate(mm, pud, new); |
2133 | #else |
2134 | if (pgd_present(*pud)) { |
2135 | pmd_free(new); |
2136 | goto out; |
2137 | } |
2138 | pgd_populate(mm, pud, new); |
2139 | #endif /* __ARCH_HAS_4LEVEL_HACK */ |
2140 | |
2141 | out: |
2142 | return pmd_offset(pud, address); |
2143 | } |
2144 | #endif /* __PAGETABLE_PMD_FOLDED */ |
2145 | |
2146 | int make_pages_present(unsigned long addr, unsigned long end) |
2147 | { |
2148 | int ret, len, write; |
2149 | struct vm_area_struct * vma; |
2150 | |
2151 | vma = find_vma(current->mm, addr); |
2152 | if (!vma) |
2153 | return -1; |
2154 | write = (vma->vm_flags & VM_WRITE) != 0; |
2155 | if (addr >= end) |
2156 | BUG(); |
2157 | if (end > vma->vm_end) |
2158 | BUG(); |
2159 | len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; |
2160 | ret = get_user_pages(current, current->mm, addr, |
2161 | len, write, 0, NULL, NULL); |
2162 | if (ret < 0) |
2163 | return ret; |
2164 | return ret == len ? 0 : -1; |
2165 | } |
2166 | |
2167 | /* |
2168 | * Map a vmalloc()-space virtual address to the physical page. |
2169 | */ |
2170 | struct page * vmalloc_to_page(void * vmalloc_addr) |
2171 | { |
2172 | unsigned long addr = (unsigned long) vmalloc_addr; |
2173 | struct page *page = NULL; |
2174 | pgd_t *pgd = pgd_offset_k(addr); |
2175 | pud_t *pud; |
2176 | pmd_t *pmd; |
2177 | pte_t *ptep, pte; |
2178 | |
2179 | if (!pgd_none(*pgd)) { |
2180 | pud = pud_offset(pgd, addr); |
2181 | if (!pud_none(*pud)) { |
2182 | pmd = pmd_offset(pud, addr); |
2183 | if (!pmd_none(*pmd)) { |
2184 | ptep = pte_offset_map(pmd, addr); |
2185 | pte = *ptep; |
2186 | if (pte_present(pte)) |
2187 | page = pte_page(pte); |
2188 | pte_unmap(ptep); |
2189 | } |
2190 | } |
2191 | } |
2192 | return page; |
2193 | } |
2194 | |
2195 | EXPORT_SYMBOL(vmalloc_to_page); |
2196 | |
2197 | /* |
2198 | * Map a vmalloc()-space virtual address to the physical page frame number. |
2199 | */ |
2200 | unsigned long vmalloc_to_pfn(void * vmalloc_addr) |
2201 | { |
2202 | return page_to_pfn(vmalloc_to_page(vmalloc_addr)); |
2203 | } |
2204 | |
2205 | EXPORT_SYMBOL(vmalloc_to_pfn); |
2206 | |
2207 | /* |
2208 | * update_mem_hiwater |
2209 | * - update per process rss and vm high water data |
2210 | */ |
2211 | void update_mem_hiwater(struct task_struct *tsk) |
2212 | { |
2213 | if (tsk->mm) { |
2214 | unsigned long rss = get_mm_counter(tsk->mm, rss); |
2215 | |
2216 | if (tsk->mm->hiwater_rss < rss) |
2217 | tsk->mm->hiwater_rss = rss; |
2218 | if (tsk->mm->hiwater_vm < tsk->mm->total_vm) |
2219 | tsk->mm->hiwater_vm = tsk->mm->total_vm; |
2220 | } |
2221 | } |
2222 | |
2223 | #if !defined(__HAVE_ARCH_GATE_AREA) |
2224 | |
2225 | #if defined(AT_SYSINFO_EHDR) |
2226 | struct vm_area_struct gate_vma; |
2227 | |
2228 | static int __init gate_vma_init(void) |
2229 | { |
2230 | gate_vma.vm_mm = NULL; |
2231 | gate_vma.vm_start = FIXADDR_USER_START; |
2232 | gate_vma.vm_end = FIXADDR_USER_END; |
2233 | gate_vma.vm_page_prot = PAGE_READONLY; |
2234 | gate_vma.vm_flags = 0; |
2235 | return 0; |
2236 | } |
2237 | __initcall(gate_vma_init); |
2238 | #endif |
2239 | |
2240 | struct vm_area_struct *get_gate_vma(struct task_struct *tsk) |
2241 | { |
2242 | #ifdef AT_SYSINFO_EHDR |
2243 | return &gate_vma; |
2244 | #else |
2245 | return NULL; |
2246 | #endif |
2247 | } |
2248 | |
2249 | int in_gate_area_no_task(unsigned long addr) |
2250 | { |
2251 | #ifdef AT_SYSINFO_EHDR |
2252 | if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) |
2253 | return 1; |
2254 | #endif |
2255 | return 0; |
2256 | } |
2257 | |
2258 | #endif /* __HAVE_ARCH_GATE_AREA */ |