blob: b8846cf2358a54fb9903568fc50dbd69ab3d2bce [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
63unsigned long max_mapnr;
64struct page *mem_map;
65
66EXPORT_SYMBOL(max_mapnr);
67EXPORT_SYMBOL(mem_map);
68#endif
69
70unsigned 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 */
78void * high_memory;
79unsigned long vmalloc_earlyreserve;
80
81EXPORT_SYMBOL(num_physpages);
82EXPORT_SYMBOL(high_memory);
83EXPORT_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
91void pgd_clear_bad(pgd_t *pgd)
92{
93 pgd_ERROR(*pgd);
94 pgd_clear(pgd);
95}
96
97void pud_clear_bad(pud_t *pud)
98{
99 pud_ERROR(*pud);
100 pud_clear(pud);
101}
102
103void 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 */
Hugh Dickinse0da3822005-04-19 13:29:15 -0700113static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114{
Hugh Dickinse0da3822005-04-19 13:29:15 -0700115 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--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120}
121
Hugh Dickinse0da3822005-04-19 13:29:15 -0700122static 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)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125{
126 pmd_t *pmd;
127 unsigned long next;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700128 unsigned long start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
Hugh Dickinse0da3822005-04-19 13:29:15 -0700130 start = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 pmd = pmd_offset(pud, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 do {
133 next = pmd_addr_end(addr, end);
134 if (pmd_none_or_clear_bad(pmd))
135 continue;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700136 free_pte_range(tlb, pmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 } while (pmd++, addr = next, addr != end);
138
Hugh Dickinse0da3822005-04-19 13:29:15 -0700139 start &= PUD_MASK;
140 if (start < floor)
141 return;
142 if (ceiling) {
143 ceiling &= PUD_MASK;
144 if (!ceiling)
145 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 }
Hugh Dickinse0da3822005-04-19 13:29:15 -0700147 if (end - 1 > ceiling - 1)
148 return;
149
150 pmd = pmd_offset(pud, start);
151 pud_clear(pud);
152 pmd_free_tlb(tlb, pmd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153}
154
Hugh Dickinse0da3822005-04-19 13:29:15 -0700155static 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)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158{
159 pud_t *pud;
160 unsigned long next;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700161 unsigned long start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162
Hugh Dickinse0da3822005-04-19 13:29:15 -0700163 start = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 pud = pud_offset(pgd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 do {
166 next = pud_addr_end(addr, end);
167 if (pud_none_or_clear_bad(pud))
168 continue;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700169 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 } while (pud++, addr = next, addr != end);
171
Hugh Dickinse0da3822005-04-19 13:29:15 -0700172 start &= PGDIR_MASK;
173 if (start < floor)
174 return;
175 if (ceiling) {
176 ceiling &= PGDIR_MASK;
177 if (!ceiling)
178 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 }
Hugh Dickinse0da3822005-04-19 13:29:15 -0700180 if (end - 1 > ceiling - 1)
181 return;
182
183 pud = pud_offset(pgd, start);
184 pgd_clear(pgd);
185 pud_free_tlb(tlb, pud);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186}
187
188/*
Hugh Dickinse0da3822005-04-19 13:29:15 -0700189 * This function frees user-level page tables of a process.
190 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 * Must be called with pagetable lock held.
192 */
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700193void free_pgd_range(struct mmu_gather **tlb,
Hugh Dickinse0da3822005-04-19 13:29:15 -0700194 unsigned long addr, unsigned long end,
195 unsigned long floor, unsigned long ceiling)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196{
197 pgd_t *pgd;
198 unsigned long next;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700199 unsigned long start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Hugh Dickinse0da3822005-04-19 13:29:15 -0700201 /*
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;
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700244 pgd = pgd_offset((*tlb)->mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 do {
246 next = pgd_addr_end(addr, end);
247 if (pgd_none_or_clear_bad(pgd))
248 continue;
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700249 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 } while (pgd++, addr = next, addr != end);
Hugh Dickinse0da3822005-04-19 13:29:15 -0700251
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700252 if (!tlb_is_full_mm(*tlb))
253 flush_tlb_pgtables((*tlb)->mm, start, end);
Hugh Dickinse0da3822005-04-19 13:29:15 -0700254}
255
256void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700257 unsigned long floor, unsigned long ceiling)
Hugh Dickinse0da3822005-04-19 13:29:15 -0700258{
259 while (vma) {
260 struct vm_area_struct *next = vma->vm_next;
261 unsigned long addr = vma->vm_start;
262
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700263 if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) {
264 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
Hugh Dickinse0da3822005-04-19 13:29:15 -0700265 floor, next? next->vm_start: ceiling);
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700266 } 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 }
Hugh Dickinse0da3822005-04-19 13:29:15 -0700279 vma = next;
280 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281}
282
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700283pte_t fastcall *pte_alloc_map(struct mm_struct *mm, pmd_t *pmd,
284 unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285{
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 }
306out:
307 return pte_offset_map(pmd, address);
308}
309
310pte_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 }
331out:
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
344static inline void
345copy_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
407static 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
415again:
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
449static 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
471static 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
493int 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
517static 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
587static 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
603static 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
619static 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 *
Hugh Dickinsee39b372005-04-19 13:29:15 -0700658 * Returns the end address of the unmapping (restart addr if interrupted).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 *
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 */
Hugh Dickinsee39b372005-04-19 13:29:15 -0700675unsigned long unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 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;
Hugh Dickinsee39b372005-04-19 13:29:15 -0700683 unsigned long start = start_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 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) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 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 }
742out:
Hugh Dickinsee39b372005-04-19 13:29:15 -0700743 return start; /* which is now the end (or restart) address */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744}
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 */
Hugh Dickinsee39b372005-04-19 13:29:15 -0700753unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 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);
Hugh Dickinsee39b372005-04-19 13:29:15 -0700763 return end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 }
765
766 lru_add_drain();
767 spin_lock(&mm->page_table_lock);
768 tlb = tlb_gather_mmu(mm, 0);
Hugh Dickinsee39b372005-04-19 13:29:15 -0700769 end = unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 tlb_finish_mmu(tlb, address, end);
771 spin_unlock(&mm->page_table_lock);
Hugh Dickinsee39b372005-04-19 13:29:15 -0700772 return end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773}
774
775/*
776 * Do a quick page-table lookup for a single page.
777 * mm->page_table_lock must be held.
778 */
779static 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
828out:
829 return NULL;
830}
831
832struct page *
833follow_page(struct mm_struct *mm, unsigned long address, int write)
834{
835 return __follow_page(mm, address, /*read*/0, write);
836}
837
838int
839check_user_page_readable(struct mm_struct *mm, unsigned long address)
840{
841 return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
842}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843EXPORT_SYMBOL(check_user_page_readable);
844
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845static inline int
846untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
847 unsigned long address)
848{
849 pgd_t *pgd;
850 pud_t *pud;
851 pmd_t *pmd;
852
853 /* Check if the vma is for an anonymous mapping. */
854 if (vma->vm_ops && vma->vm_ops->nopage)
855 return 0;
856
857 /* Check if page directory entry exists. */
858 pgd = pgd_offset(mm, address);
859 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
860 return 1;
861
862 pud = pud_offset(pgd, address);
863 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
864 return 1;
865
866 /* Check if page middle directory entry exists. */
867 pmd = pmd_offset(pud, address);
868 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
869 return 1;
870
871 /* There is a pte slot for 'address' in 'mm'. */
872 return 0;
873}
874
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
876 unsigned long start, int len, int write, int force,
877 struct page **pages, struct vm_area_struct **vmas)
878{
879 int i;
880 unsigned int flags;
881
882 /*
883 * Require read or write permissions.
884 * If 'force' is set, we only require the "MAY" flags.
885 */
886 flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
887 flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
888 i = 0;
889
890 do {
891 struct vm_area_struct * vma;
892
893 vma = find_extend_vma(mm, start);
894 if (!vma && in_gate_area(tsk, start)) {
895 unsigned long pg = start & PAGE_MASK;
896 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
897 pgd_t *pgd;
898 pud_t *pud;
899 pmd_t *pmd;
900 pte_t *pte;
901 if (write) /* user gate pages are read-only */
902 return i ? : -EFAULT;
903 if (pg > TASK_SIZE)
904 pgd = pgd_offset_k(pg);
905 else
906 pgd = pgd_offset_gate(mm, pg);
907 BUG_ON(pgd_none(*pgd));
908 pud = pud_offset(pgd, pg);
909 BUG_ON(pud_none(*pud));
910 pmd = pmd_offset(pud, pg);
911 BUG_ON(pmd_none(*pmd));
912 pte = pte_offset_map(pmd, pg);
913 BUG_ON(pte_none(*pte));
914 if (pages) {
915 pages[i] = pte_page(*pte);
916 get_page(pages[i]);
917 }
918 pte_unmap(pte);
919 if (vmas)
920 vmas[i] = gate_vma;
921 i++;
922 start += PAGE_SIZE;
923 len--;
924 continue;
925 }
926
927 if (!vma || (vma->vm_flags & VM_IO)
928 || !(flags & vma->vm_flags))
929 return i ? : -EFAULT;
930
931 if (is_vm_hugetlb_page(vma)) {
932 i = follow_hugetlb_page(mm, vma, pages, vmas,
933 &start, &len, i);
934 continue;
935 }
936 spin_lock(&mm->page_table_lock);
937 do {
Hugh Dickins08ef4722005-06-21 17:15:10 -0700938 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939 int lookup_write = write;
940
941 cond_resched_lock(&mm->page_table_lock);
Hugh Dickins08ef4722005-06-21 17:15:10 -0700942 while (!(page = follow_page(mm, start, lookup_write))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943 /*
944 * Shortcut for anonymous pages. We don't want
945 * to force the creation of pages tables for
Hugh Dickins08ef4722005-06-21 17:15:10 -0700946 * insanely big anonymously mapped areas that
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947 * nobody touched so far. This is important
948 * for doing a core dump for these mappings.
949 */
950 if (!lookup_write &&
951 untouched_anonymous_page(mm,vma,start)) {
Hugh Dickins08ef4722005-06-21 17:15:10 -0700952 page = ZERO_PAGE(start);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 break;
954 }
955 spin_unlock(&mm->page_table_lock);
956 switch (handle_mm_fault(mm,vma,start,write)) {
957 case VM_FAULT_MINOR:
958 tsk->min_flt++;
959 break;
960 case VM_FAULT_MAJOR:
961 tsk->maj_flt++;
962 break;
963 case VM_FAULT_SIGBUS:
964 return i ? i : -EFAULT;
965 case VM_FAULT_OOM:
966 return i ? i : -ENOMEM;
967 default:
968 BUG();
969 }
970 /*
971 * Now that we have performed a write fault
972 * and surely no longer have a shared page we
973 * shouldn't write, we shouldn't ignore an
974 * unwritable page in the page table if
975 * we are forcing write access.
976 */
977 lookup_write = write && !force;
978 spin_lock(&mm->page_table_lock);
979 }
980 if (pages) {
Hugh Dickins08ef4722005-06-21 17:15:10 -0700981 pages[i] = page;
982 flush_dcache_page(page);
983 if (!PageReserved(page))
984 page_cache_get(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 }
986 if (vmas)
987 vmas[i] = vma;
988 i++;
989 start += PAGE_SIZE;
990 len--;
Hugh Dickins08ef4722005-06-21 17:15:10 -0700991 } while (len && start < vma->vm_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 spin_unlock(&mm->page_table_lock);
Hugh Dickins08ef4722005-06-21 17:15:10 -0700993 } while (len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 return i;
995}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996EXPORT_SYMBOL(get_user_pages);
997
998static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
999 unsigned long addr, unsigned long end, pgprot_t prot)
1000{
1001 pte_t *pte;
1002
1003 pte = pte_alloc_map(mm, pmd, addr);
1004 if (!pte)
1005 return -ENOMEM;
1006 do {
1007 pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(addr), prot));
1008 BUG_ON(!pte_none(*pte));
1009 set_pte_at(mm, addr, pte, zero_pte);
1010 } while (pte++, addr += PAGE_SIZE, addr != end);
1011 pte_unmap(pte - 1);
1012 return 0;
1013}
1014
1015static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1016 unsigned long addr, unsigned long end, pgprot_t prot)
1017{
1018 pmd_t *pmd;
1019 unsigned long next;
1020
1021 pmd = pmd_alloc(mm, pud, addr);
1022 if (!pmd)
1023 return -ENOMEM;
1024 do {
1025 next = pmd_addr_end(addr, end);
1026 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1027 return -ENOMEM;
1028 } while (pmd++, addr = next, addr != end);
1029 return 0;
1030}
1031
1032static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1033 unsigned long addr, unsigned long end, pgprot_t prot)
1034{
1035 pud_t *pud;
1036 unsigned long next;
1037
1038 pud = pud_alloc(mm, pgd, addr);
1039 if (!pud)
1040 return -ENOMEM;
1041 do {
1042 next = pud_addr_end(addr, end);
1043 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1044 return -ENOMEM;
1045 } while (pud++, addr = next, addr != end);
1046 return 0;
1047}
1048
1049int zeromap_page_range(struct vm_area_struct *vma,
1050 unsigned long addr, unsigned long size, pgprot_t prot)
1051{
1052 pgd_t *pgd;
1053 unsigned long next;
1054 unsigned long end = addr + size;
1055 struct mm_struct *mm = vma->vm_mm;
1056 int err;
1057
1058 BUG_ON(addr >= end);
1059 pgd = pgd_offset(mm, addr);
1060 flush_cache_range(vma, addr, end);
1061 spin_lock(&mm->page_table_lock);
1062 do {
1063 next = pgd_addr_end(addr, end);
1064 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1065 if (err)
1066 break;
1067 } while (pgd++, addr = next, addr != end);
1068 spin_unlock(&mm->page_table_lock);
1069 return err;
1070}
1071
1072/*
1073 * maps a range of physical memory into the requested pages. the old
1074 * mappings are removed. any references to nonexistent pages results
1075 * in null mappings (currently treated as "copy-on-access")
1076 */
1077static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1078 unsigned long addr, unsigned long end,
1079 unsigned long pfn, pgprot_t prot)
1080{
1081 pte_t *pte;
1082
1083 pte = pte_alloc_map(mm, pmd, addr);
1084 if (!pte)
1085 return -ENOMEM;
1086 do {
1087 BUG_ON(!pte_none(*pte));
1088 if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn)))
1089 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1090 pfn++;
1091 } while (pte++, addr += PAGE_SIZE, addr != end);
1092 pte_unmap(pte - 1);
1093 return 0;
1094}
1095
1096static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1097 unsigned long addr, unsigned long end,
1098 unsigned long pfn, pgprot_t prot)
1099{
1100 pmd_t *pmd;
1101 unsigned long next;
1102
1103 pfn -= addr >> PAGE_SHIFT;
1104 pmd = pmd_alloc(mm, pud, addr);
1105 if (!pmd)
1106 return -ENOMEM;
1107 do {
1108 next = pmd_addr_end(addr, end);
1109 if (remap_pte_range(mm, pmd, addr, next,
1110 pfn + (addr >> PAGE_SHIFT), prot))
1111 return -ENOMEM;
1112 } while (pmd++, addr = next, addr != end);
1113 return 0;
1114}
1115
1116static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1117 unsigned long addr, unsigned long end,
1118 unsigned long pfn, pgprot_t prot)
1119{
1120 pud_t *pud;
1121 unsigned long next;
1122
1123 pfn -= addr >> PAGE_SHIFT;
1124 pud = pud_alloc(mm, pgd, addr);
1125 if (!pud)
1126 return -ENOMEM;
1127 do {
1128 next = pud_addr_end(addr, end);
1129 if (remap_pmd_range(mm, pud, addr, next,
1130 pfn + (addr >> PAGE_SHIFT), prot))
1131 return -ENOMEM;
1132 } while (pud++, addr = next, addr != end);
1133 return 0;
1134}
1135
1136/* Note: this is only safe if the mm semaphore is held when called. */
1137int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1138 unsigned long pfn, unsigned long size, pgprot_t prot)
1139{
1140 pgd_t *pgd;
1141 unsigned long next;
1142 unsigned long end = addr + size;
1143 struct mm_struct *mm = vma->vm_mm;
1144 int err;
1145
1146 /*
1147 * Physically remapped pages are special. Tell the
1148 * rest of the world about it:
1149 * VM_IO tells people not to look at these pages
1150 * (accesses can have side effects).
1151 * VM_RESERVED tells swapout not to try to touch
1152 * this region.
1153 */
1154 vma->vm_flags |= VM_IO | VM_RESERVED;
1155
1156 BUG_ON(addr >= end);
1157 pfn -= addr >> PAGE_SHIFT;
1158 pgd = pgd_offset(mm, addr);
1159 flush_cache_range(vma, addr, end);
1160 spin_lock(&mm->page_table_lock);
1161 do {
1162 next = pgd_addr_end(addr, end);
1163 err = remap_pud_range(mm, pgd, addr, next,
1164 pfn + (addr >> PAGE_SHIFT), prot);
1165 if (err)
1166 break;
1167 } while (pgd++, addr = next, addr != end);
1168 spin_unlock(&mm->page_table_lock);
1169 return err;
1170}
1171EXPORT_SYMBOL(remap_pfn_range);
1172
1173/*
1174 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
1175 * servicing faults for write access. In the normal case, do always want
1176 * pte_mkwrite. But get_user_pages can cause write faults for mappings
1177 * that do not have writing enabled, when used by access_process_vm.
1178 */
1179static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1180{
1181 if (likely(vma->vm_flags & VM_WRITE))
1182 pte = pte_mkwrite(pte);
1183 return pte;
1184}
1185
1186/*
1187 * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock
1188 */
1189static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address,
1190 pte_t *page_table)
1191{
1192 pte_t entry;
1193
1194 entry = maybe_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot)),
1195 vma);
1196 ptep_establish(vma, address, page_table, entry);
1197 update_mmu_cache(vma, address, entry);
1198 lazy_mmu_prot_update(entry);
1199}
1200
1201/*
1202 * This routine handles present pages, when users try to write
1203 * to a shared page. It is done by copying the page to a new address
1204 * and decrementing the shared-page counter for the old page.
1205 *
1206 * Goto-purists beware: the only reason for goto's here is that it results
1207 * in better assembly code.. The "default" path will see no jumps at all.
1208 *
1209 * Note that this routine assumes that the protection checks have been
1210 * done by the caller (the low-level page fault routine in most cases).
1211 * Thus we can safely just mark it writable once we've done any necessary
1212 * COW.
1213 *
1214 * We also mark the page dirty at this point even though the page will
1215 * change only once the write actually happens. This avoids a few races,
1216 * and potentially makes it more efficient.
1217 *
1218 * We hold the mm semaphore and the page_table_lock on entry and exit
1219 * with the page_table_lock released.
1220 */
1221static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
1222 unsigned long address, pte_t *page_table, pmd_t *pmd, pte_t pte)
1223{
1224 struct page *old_page, *new_page;
1225 unsigned long pfn = pte_pfn(pte);
1226 pte_t entry;
1227
1228 if (unlikely(!pfn_valid(pfn))) {
1229 /*
1230 * This should really halt the system so it can be debugged or
1231 * at least the kernel stops what it's doing before it corrupts
1232 * data, but for the moment just pretend this is OOM.
1233 */
1234 pte_unmap(page_table);
1235 printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n",
1236 address);
1237 spin_unlock(&mm->page_table_lock);
1238 return VM_FAULT_OOM;
1239 }
1240 old_page = pfn_to_page(pfn);
1241
1242 if (!TestSetPageLocked(old_page)) {
1243 int reuse = can_share_swap_page(old_page);
1244 unlock_page(old_page);
1245 if (reuse) {
1246 flush_cache_page(vma, address, pfn);
1247 entry = maybe_mkwrite(pte_mkyoung(pte_mkdirty(pte)),
1248 vma);
1249 ptep_set_access_flags(vma, address, page_table, entry, 1);
1250 update_mmu_cache(vma, address, entry);
1251 lazy_mmu_prot_update(entry);
1252 pte_unmap(page_table);
1253 spin_unlock(&mm->page_table_lock);
1254 return VM_FAULT_MINOR;
1255 }
1256 }
1257 pte_unmap(page_table);
1258
1259 /*
1260 * Ok, we need to copy. Oh, well..
1261 */
1262 if (!PageReserved(old_page))
1263 page_cache_get(old_page);
1264 spin_unlock(&mm->page_table_lock);
1265
1266 if (unlikely(anon_vma_prepare(vma)))
1267 goto no_new_page;
1268 if (old_page == ZERO_PAGE(address)) {
1269 new_page = alloc_zeroed_user_highpage(vma, address);
1270 if (!new_page)
1271 goto no_new_page;
1272 } else {
1273 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1274 if (!new_page)
1275 goto no_new_page;
1276 copy_user_highpage(new_page, old_page, address);
1277 }
1278 /*
1279 * Re-check the pte - we dropped the lock
1280 */
1281 spin_lock(&mm->page_table_lock);
1282 page_table = pte_offset_map(pmd, address);
1283 if (likely(pte_same(*page_table, pte))) {
1284 if (PageAnon(old_page))
1285 dec_mm_counter(mm, anon_rss);
1286 if (PageReserved(old_page))
1287 inc_mm_counter(mm, rss);
1288 else
1289 page_remove_rmap(old_page);
1290 flush_cache_page(vma, address, pfn);
1291 break_cow(vma, new_page, address, page_table);
1292 lru_cache_add_active(new_page);
1293 page_add_anon_rmap(new_page, vma, address);
1294
1295 /* Free the old page.. */
1296 new_page = old_page;
1297 }
1298 pte_unmap(page_table);
1299 page_cache_release(new_page);
1300 page_cache_release(old_page);
1301 spin_unlock(&mm->page_table_lock);
1302 return VM_FAULT_MINOR;
1303
1304no_new_page:
1305 page_cache_release(old_page);
1306 return VM_FAULT_OOM;
1307}
1308
1309/*
1310 * Helper functions for unmap_mapping_range().
1311 *
1312 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1313 *
1314 * We have to restart searching the prio_tree whenever we drop the lock,
1315 * since the iterator is only valid while the lock is held, and anyway
1316 * a later vma might be split and reinserted earlier while lock dropped.
1317 *
1318 * The list of nonlinear vmas could be handled more efficiently, using
1319 * a placeholder, but handle it in the same way until a need is shown.
1320 * It is important to search the prio_tree before nonlinear list: a vma
1321 * may become nonlinear and be shifted from prio_tree to nonlinear list
1322 * while the lock is dropped; but never shifted from list to prio_tree.
1323 *
1324 * In order to make forward progress despite restarting the search,
1325 * vm_truncate_count is used to mark a vma as now dealt with, so we can
1326 * quickly skip it next time around. Since the prio_tree search only
1327 * shows us those vmas affected by unmapping the range in question, we
1328 * can't efficiently keep all vmas in step with mapping->truncate_count:
1329 * so instead reset them all whenever it wraps back to 0 (then go to 1).
1330 * mapping->truncate_count and vma->vm_truncate_count are protected by
1331 * i_mmap_lock.
1332 *
1333 * In order to make forward progress despite repeatedly restarting some
Hugh Dickinsee39b372005-04-19 13:29:15 -07001334 * large vma, note the restart_addr from unmap_vmas when it breaks out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 * and restart from that address when we reach that vma again. It might
1336 * have been split or merged, shrunk or extended, but never shifted: so
1337 * restart_addr remains valid so long as it remains in the vma's range.
1338 * unmap_mapping_range forces truncate_count to leap over page-aligned
1339 * values so we can save vma's restart_addr in its truncate_count field.
1340 */
1341#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1342
1343static void reset_vma_truncate_counts(struct address_space *mapping)
1344{
1345 struct vm_area_struct *vma;
1346 struct prio_tree_iter iter;
1347
1348 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1349 vma->vm_truncate_count = 0;
1350 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1351 vma->vm_truncate_count = 0;
1352}
1353
1354static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1355 unsigned long start_addr, unsigned long end_addr,
1356 struct zap_details *details)
1357{
1358 unsigned long restart_addr;
1359 int need_break;
1360
1361again:
1362 restart_addr = vma->vm_truncate_count;
1363 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1364 start_addr = restart_addr;
1365 if (start_addr >= end_addr) {
1366 /* Top of vma has been split off since last time */
1367 vma->vm_truncate_count = details->truncate_count;
1368 return 0;
1369 }
1370 }
1371
Hugh Dickinsee39b372005-04-19 13:29:15 -07001372 restart_addr = zap_page_range(vma, start_addr,
1373 end_addr - start_addr, details);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374
1375 /*
1376 * We cannot rely on the break test in unmap_vmas:
1377 * on the one hand, we don't want to restart our loop
1378 * just because that broke out for the page_table_lock;
1379 * on the other hand, it does no test when vma is small.
1380 */
1381 need_break = need_resched() ||
1382 need_lockbreak(details->i_mmap_lock);
1383
Hugh Dickinsee39b372005-04-19 13:29:15 -07001384 if (restart_addr >= end_addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 /* We have now completed this vma: mark it so */
1386 vma->vm_truncate_count = details->truncate_count;
1387 if (!need_break)
1388 return 0;
1389 } else {
1390 /* Note restart_addr in vma's truncate_count field */
Hugh Dickinsee39b372005-04-19 13:29:15 -07001391 vma->vm_truncate_count = restart_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 if (!need_break)
1393 goto again;
1394 }
1395
1396 spin_unlock(details->i_mmap_lock);
1397 cond_resched();
1398 spin_lock(details->i_mmap_lock);
1399 return -EINTR;
1400}
1401
1402static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1403 struct zap_details *details)
1404{
1405 struct vm_area_struct *vma;
1406 struct prio_tree_iter iter;
1407 pgoff_t vba, vea, zba, zea;
1408
1409restart:
1410 vma_prio_tree_foreach(vma, &iter, root,
1411 details->first_index, details->last_index) {
1412 /* Skip quickly over those we have already dealt with */
1413 if (vma->vm_truncate_count == details->truncate_count)
1414 continue;
1415
1416 vba = vma->vm_pgoff;
1417 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1418 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1419 zba = details->first_index;
1420 if (zba < vba)
1421 zba = vba;
1422 zea = details->last_index;
1423 if (zea > vea)
1424 zea = vea;
1425
1426 if (unmap_mapping_range_vma(vma,
1427 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1428 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1429 details) < 0)
1430 goto restart;
1431 }
1432}
1433
1434static inline void unmap_mapping_range_list(struct list_head *head,
1435 struct zap_details *details)
1436{
1437 struct vm_area_struct *vma;
1438
1439 /*
1440 * In nonlinear VMAs there is no correspondence between virtual address
1441 * offset and file offset. So we must perform an exhaustive search
1442 * across *all* the pages in each nonlinear VMA, not just the pages
1443 * whose virtual address lies outside the file truncation point.
1444 */
1445restart:
1446 list_for_each_entry(vma, head, shared.vm_set.list) {
1447 /* Skip quickly over those we have already dealt with */
1448 if (vma->vm_truncate_count == details->truncate_count)
1449 continue;
1450 details->nonlinear_vma = vma;
1451 if (unmap_mapping_range_vma(vma, vma->vm_start,
1452 vma->vm_end, details) < 0)
1453 goto restart;
1454 }
1455}
1456
1457/**
1458 * unmap_mapping_range - unmap the portion of all mmaps
1459 * in the specified address_space corresponding to the specified
1460 * page range in the underlying file.
1461 * @address_space: the address space containing mmaps to be unmapped.
1462 * @holebegin: byte in first page to unmap, relative to the start of
1463 * the underlying file. This will be rounded down to a PAGE_SIZE
1464 * boundary. Note that this is different from vmtruncate(), which
1465 * must keep the partial page. In contrast, we must get rid of
1466 * partial pages.
1467 * @holelen: size of prospective hole in bytes. This will be rounded
1468 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
1469 * end of the file.
1470 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1471 * but 0 when invalidating pagecache, don't throw away private data.
1472 */
1473void unmap_mapping_range(struct address_space *mapping,
1474 loff_t const holebegin, loff_t const holelen, int even_cows)
1475{
1476 struct zap_details details;
1477 pgoff_t hba = holebegin >> PAGE_SHIFT;
1478 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1479
1480 /* Check for overflow. */
1481 if (sizeof(holelen) > sizeof(hlen)) {
1482 long long holeend =
1483 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1484 if (holeend & ~(long long)ULONG_MAX)
1485 hlen = ULONG_MAX - hba + 1;
1486 }
1487
1488 details.check_mapping = even_cows? NULL: mapping;
1489 details.nonlinear_vma = NULL;
1490 details.first_index = hba;
1491 details.last_index = hba + hlen - 1;
1492 if (details.last_index < details.first_index)
1493 details.last_index = ULONG_MAX;
1494 details.i_mmap_lock = &mapping->i_mmap_lock;
1495
1496 spin_lock(&mapping->i_mmap_lock);
1497
1498 /* serialize i_size write against truncate_count write */
1499 smp_wmb();
1500 /* Protect against page faults, and endless unmapping loops */
1501 mapping->truncate_count++;
1502 /*
1503 * For archs where spin_lock has inclusive semantics like ia64
1504 * this smp_mb() will prevent to read pagetable contents
1505 * before the truncate_count increment is visible to
1506 * other cpus.
1507 */
1508 smp_mb();
1509 if (unlikely(is_restart_addr(mapping->truncate_count))) {
1510 if (mapping->truncate_count == 0)
1511 reset_vma_truncate_counts(mapping);
1512 mapping->truncate_count++;
1513 }
1514 details.truncate_count = mapping->truncate_count;
1515
1516 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1517 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1518 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1519 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1520 spin_unlock(&mapping->i_mmap_lock);
1521}
1522EXPORT_SYMBOL(unmap_mapping_range);
1523
1524/*
1525 * Handle all mappings that got truncated by a "truncate()"
1526 * system call.
1527 *
1528 * NOTE! We have to be ready to update the memory sharing
1529 * between the file and the memory map for a potential last
1530 * incomplete page. Ugly, but necessary.
1531 */
1532int vmtruncate(struct inode * inode, loff_t offset)
1533{
1534 struct address_space *mapping = inode->i_mapping;
1535 unsigned long limit;
1536
1537 if (inode->i_size < offset)
1538 goto do_expand;
1539 /*
1540 * truncation of in-use swapfiles is disallowed - it would cause
1541 * subsequent swapout to scribble on the now-freed blocks.
1542 */
1543 if (IS_SWAPFILE(inode))
1544 goto out_busy;
1545 i_size_write(inode, offset);
1546 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1547 truncate_inode_pages(mapping, offset);
1548 goto out_truncate;
1549
1550do_expand:
1551 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1552 if (limit != RLIM_INFINITY && offset > limit)
1553 goto out_sig;
1554 if (offset > inode->i_sb->s_maxbytes)
1555 goto out_big;
1556 i_size_write(inode, offset);
1557
1558out_truncate:
1559 if (inode->i_op && inode->i_op->truncate)
1560 inode->i_op->truncate(inode);
1561 return 0;
1562out_sig:
1563 send_sig(SIGXFSZ, current, 0);
1564out_big:
1565 return -EFBIG;
1566out_busy:
1567 return -ETXTBSY;
1568}
1569
1570EXPORT_SYMBOL(vmtruncate);
1571
1572/*
1573 * Primitive swap readahead code. We simply read an aligned block of
1574 * (1 << page_cluster) entries in the swap area. This method is chosen
1575 * because it doesn't cost us any seek time. We also make sure to queue
1576 * the 'original' request together with the readahead ones...
1577 *
1578 * This has been extended to use the NUMA policies from the mm triggering
1579 * the readahead.
1580 *
1581 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1582 */
1583void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1584{
1585#ifdef CONFIG_NUMA
1586 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1587#endif
1588 int i, num;
1589 struct page *new_page;
1590 unsigned long offset;
1591
1592 /*
1593 * Get the number of handles we should do readahead io to.
1594 */
1595 num = valid_swaphandles(entry, &offset);
1596 for (i = 0; i < num; offset++, i++) {
1597 /* Ok, do the async read-ahead now */
1598 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1599 offset), vma, addr);
1600 if (!new_page)
1601 break;
1602 page_cache_release(new_page);
1603#ifdef CONFIG_NUMA
1604 /*
1605 * Find the next applicable VMA for the NUMA policy.
1606 */
1607 addr += PAGE_SIZE;
1608 if (addr == 0)
1609 vma = NULL;
1610 if (vma) {
1611 if (addr >= vma->vm_end) {
1612 vma = next_vma;
1613 next_vma = vma ? vma->vm_next : NULL;
1614 }
1615 if (vma && addr < vma->vm_start)
1616 vma = NULL;
1617 } else {
1618 if (next_vma && addr >= next_vma->vm_start) {
1619 vma = next_vma;
1620 next_vma = vma->vm_next;
1621 }
1622 }
1623#endif
1624 }
1625 lru_add_drain(); /* Push any new pages onto the LRU now */
1626}
1627
1628/*
1629 * We hold the mm semaphore and the page_table_lock on entry and
1630 * should release the pagetable lock on exit..
1631 */
1632static int do_swap_page(struct mm_struct * mm,
1633 struct vm_area_struct * vma, unsigned long address,
1634 pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access)
1635{
1636 struct page *page;
1637 swp_entry_t entry = pte_to_swp_entry(orig_pte);
1638 pte_t pte;
1639 int ret = VM_FAULT_MINOR;
1640
1641 pte_unmap(page_table);
1642 spin_unlock(&mm->page_table_lock);
1643 page = lookup_swap_cache(entry);
1644 if (!page) {
1645 swapin_readahead(entry, address, vma);
1646 page = read_swap_cache_async(entry, vma, address);
1647 if (!page) {
1648 /*
1649 * Back out if somebody else faulted in this pte while
1650 * we released the page table lock.
1651 */
1652 spin_lock(&mm->page_table_lock);
1653 page_table = pte_offset_map(pmd, address);
1654 if (likely(pte_same(*page_table, orig_pte)))
1655 ret = VM_FAULT_OOM;
1656 else
1657 ret = VM_FAULT_MINOR;
1658 pte_unmap(page_table);
1659 spin_unlock(&mm->page_table_lock);
1660 goto out;
1661 }
1662
1663 /* Had to read the page from swap area: Major fault */
1664 ret = VM_FAULT_MAJOR;
1665 inc_page_state(pgmajfault);
1666 grab_swap_token();
1667 }
1668
1669 mark_page_accessed(page);
1670 lock_page(page);
1671
1672 /*
1673 * Back out if somebody else faulted in this pte while we
1674 * released the page table lock.
1675 */
1676 spin_lock(&mm->page_table_lock);
1677 page_table = pte_offset_map(pmd, address);
1678 if (unlikely(!pte_same(*page_table, orig_pte))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 ret = VM_FAULT_MINOR;
Kirill Korotaevb8107482005-05-16 21:53:50 -07001680 goto out_nomap;
1681 }
1682
1683 if (unlikely(!PageUptodate(page))) {
1684 ret = VM_FAULT_SIGBUS;
1685 goto out_nomap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 }
1687
1688 /* The page isn't present yet, go ahead with the fault. */
1689
1690 swap_free(entry);
1691 if (vm_swap_full())
1692 remove_exclusive_swap_page(page);
1693
1694 inc_mm_counter(mm, rss);
1695 pte = mk_pte(page, vma->vm_page_prot);
1696 if (write_access && can_share_swap_page(page)) {
1697 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1698 write_access = 0;
1699 }
1700 unlock_page(page);
1701
1702 flush_icache_page(vma, page);
1703 set_pte_at(mm, address, page_table, pte);
1704 page_add_anon_rmap(page, vma, address);
1705
1706 if (write_access) {
1707 if (do_wp_page(mm, vma, address,
1708 page_table, pmd, pte) == VM_FAULT_OOM)
1709 ret = VM_FAULT_OOM;
1710 goto out;
1711 }
1712
1713 /* No need to invalidate - it was non-present before */
1714 update_mmu_cache(vma, address, pte);
1715 lazy_mmu_prot_update(pte);
1716 pte_unmap(page_table);
1717 spin_unlock(&mm->page_table_lock);
1718out:
1719 return ret;
Kirill Korotaevb8107482005-05-16 21:53:50 -07001720out_nomap:
1721 pte_unmap(page_table);
1722 spin_unlock(&mm->page_table_lock);
1723 unlock_page(page);
1724 page_cache_release(page);
1725 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726}
1727
1728/*
1729 * We are called with the MM semaphore and page_table_lock
1730 * spinlock held to protect against concurrent faults in
1731 * multithreaded programs.
1732 */
1733static int
1734do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
1735 pte_t *page_table, pmd_t *pmd, int write_access,
1736 unsigned long addr)
1737{
1738 pte_t entry;
1739 struct page * page = ZERO_PAGE(addr);
1740
1741 /* Read-only mapping of ZERO_PAGE. */
1742 entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot));
1743
1744 /* ..except if it's a write access */
1745 if (write_access) {
1746 /* Allocate our own private page. */
1747 pte_unmap(page_table);
1748 spin_unlock(&mm->page_table_lock);
1749
1750 if (unlikely(anon_vma_prepare(vma)))
1751 goto no_mem;
1752 page = alloc_zeroed_user_highpage(vma, addr);
1753 if (!page)
1754 goto no_mem;
1755
1756 spin_lock(&mm->page_table_lock);
1757 page_table = pte_offset_map(pmd, addr);
1758
1759 if (!pte_none(*page_table)) {
1760 pte_unmap(page_table);
1761 page_cache_release(page);
1762 spin_unlock(&mm->page_table_lock);
1763 goto out;
1764 }
1765 inc_mm_counter(mm, rss);
1766 entry = maybe_mkwrite(pte_mkdirty(mk_pte(page,
1767 vma->vm_page_prot)),
1768 vma);
1769 lru_cache_add_active(page);
1770 SetPageReferenced(page);
1771 page_add_anon_rmap(page, vma, addr);
1772 }
1773
1774 set_pte_at(mm, addr, page_table, entry);
1775 pte_unmap(page_table);
1776
1777 /* No need to invalidate - it was non-present before */
1778 update_mmu_cache(vma, addr, entry);
1779 lazy_mmu_prot_update(entry);
1780 spin_unlock(&mm->page_table_lock);
1781out:
1782 return VM_FAULT_MINOR;
1783no_mem:
1784 return VM_FAULT_OOM;
1785}
1786
1787/*
1788 * do_no_page() tries to create a new page mapping. It aggressively
1789 * tries to share with existing pages, but makes a separate copy if
1790 * the "write_access" parameter is true in order to avoid the next
1791 * page fault.
1792 *
1793 * As this is called only for pages that do not currently exist, we
1794 * do not need to flush old virtual caches or the TLB.
1795 *
1796 * This is called with the MM semaphore held and the page table
1797 * spinlock held. Exit with the spinlock released.
1798 */
1799static int
1800do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1801 unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd)
1802{
1803 struct page * new_page;
1804 struct address_space *mapping = NULL;
1805 pte_t entry;
1806 unsigned int sequence = 0;
1807 int ret = VM_FAULT_MINOR;
1808 int anon = 0;
1809
1810 if (!vma->vm_ops || !vma->vm_ops->nopage)
1811 return do_anonymous_page(mm, vma, page_table,
1812 pmd, write_access, address);
1813 pte_unmap(page_table);
1814 spin_unlock(&mm->page_table_lock);
1815
1816 if (vma->vm_file) {
1817 mapping = vma->vm_file->f_mapping;
1818 sequence = mapping->truncate_count;
1819 smp_rmb(); /* serializes i_size against truncate_count */
1820 }
1821retry:
1822 cond_resched();
1823 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
1824 /*
1825 * No smp_rmb is needed here as long as there's a full
1826 * spin_lock/unlock sequence inside the ->nopage callback
1827 * (for the pagecache lookup) that acts as an implicit
1828 * smp_mb() and prevents the i_size read to happen
1829 * after the next truncate_count read.
1830 */
1831
1832 /* no page was available -- either SIGBUS or OOM */
1833 if (new_page == NOPAGE_SIGBUS)
1834 return VM_FAULT_SIGBUS;
1835 if (new_page == NOPAGE_OOM)
1836 return VM_FAULT_OOM;
1837
1838 /*
1839 * Should we do an early C-O-W break?
1840 */
1841 if (write_access && !(vma->vm_flags & VM_SHARED)) {
1842 struct page *page;
1843
1844 if (unlikely(anon_vma_prepare(vma)))
1845 goto oom;
1846 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1847 if (!page)
1848 goto oom;
1849 copy_user_highpage(page, new_page, address);
1850 page_cache_release(new_page);
1851 new_page = page;
1852 anon = 1;
1853 }
1854
1855 spin_lock(&mm->page_table_lock);
1856 /*
1857 * For a file-backed vma, someone could have truncated or otherwise
1858 * invalidated this page. If unmap_mapping_range got called,
1859 * retry getting the page.
1860 */
1861 if (mapping && unlikely(sequence != mapping->truncate_count)) {
1862 sequence = mapping->truncate_count;
1863 spin_unlock(&mm->page_table_lock);
1864 page_cache_release(new_page);
1865 goto retry;
1866 }
1867 page_table = pte_offset_map(pmd, address);
1868
1869 /*
1870 * This silly early PAGE_DIRTY setting removes a race
1871 * due to the bad i386 page protection. But it's valid
1872 * for other architectures too.
1873 *
1874 * Note that if write_access is true, we either now have
1875 * an exclusive copy of the page, or this is a shared mapping,
1876 * so we can make it writable and dirty to avoid having to
1877 * handle that later.
1878 */
1879 /* Only go through if we didn't race with anybody else... */
1880 if (pte_none(*page_table)) {
1881 if (!PageReserved(new_page))
1882 inc_mm_counter(mm, rss);
1883
1884 flush_icache_page(vma, new_page);
1885 entry = mk_pte(new_page, vma->vm_page_prot);
1886 if (write_access)
1887 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1888 set_pte_at(mm, address, page_table, entry);
1889 if (anon) {
1890 lru_cache_add_active(new_page);
1891 page_add_anon_rmap(new_page, vma, address);
1892 } else
1893 page_add_file_rmap(new_page);
1894 pte_unmap(page_table);
1895 } else {
1896 /* One of our sibling threads was faster, back out. */
1897 pte_unmap(page_table);
1898 page_cache_release(new_page);
1899 spin_unlock(&mm->page_table_lock);
1900 goto out;
1901 }
1902
1903 /* no need to invalidate: a not-present page shouldn't be cached */
1904 update_mmu_cache(vma, address, entry);
1905 lazy_mmu_prot_update(entry);
1906 spin_unlock(&mm->page_table_lock);
1907out:
1908 return ret;
1909oom:
1910 page_cache_release(new_page);
1911 ret = VM_FAULT_OOM;
1912 goto out;
1913}
1914
1915/*
1916 * Fault of a previously existing named mapping. Repopulate the pte
1917 * from the encoded file_pte if possible. This enables swappable
1918 * nonlinear vmas.
1919 */
1920static int do_file_page(struct mm_struct * mm, struct vm_area_struct * vma,
1921 unsigned long address, int write_access, pte_t *pte, pmd_t *pmd)
1922{
1923 unsigned long pgoff;
1924 int err;
1925
1926 BUG_ON(!vma->vm_ops || !vma->vm_ops->nopage);
1927 /*
1928 * Fall back to the linear mapping if the fs does not support
1929 * ->populate:
1930 */
1931 if (!vma->vm_ops || !vma->vm_ops->populate ||
1932 (write_access && !(vma->vm_flags & VM_SHARED))) {
1933 pte_clear(mm, address, pte);
1934 return do_no_page(mm, vma, address, write_access, pte, pmd);
1935 }
1936
1937 pgoff = pte_to_pgoff(*pte);
1938
1939 pte_unmap(pte);
1940 spin_unlock(&mm->page_table_lock);
1941
1942 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, vma->vm_page_prot, pgoff, 0);
1943 if (err == -ENOMEM)
1944 return VM_FAULT_OOM;
1945 if (err)
1946 return VM_FAULT_SIGBUS;
1947 return VM_FAULT_MAJOR;
1948}
1949
1950/*
1951 * These routines also need to handle stuff like marking pages dirty
1952 * and/or accessed for architectures that don't do it in hardware (most
1953 * RISC architectures). The early dirtying is also good on the i386.
1954 *
1955 * There is also a hook called "update_mmu_cache()" that architectures
1956 * with external mmu caches can use to update those (ie the Sparc or
1957 * PowerPC hashed page tables that act as extended TLBs).
1958 *
1959 * Note the "page_table_lock". It is to protect against kswapd removing
1960 * pages from under us. Note that kswapd only ever _removes_ pages, never
1961 * adds them. As such, once we have noticed that the page is not present,
1962 * we can drop the lock early.
1963 *
1964 * The adding of pages is protected by the MM semaphore (which we hold),
1965 * so we don't need to worry about a page being suddenly been added into
1966 * our VM.
1967 *
1968 * We enter with the pagetable spinlock held, we are supposed to
1969 * release it when done.
1970 */
1971static inline int handle_pte_fault(struct mm_struct *mm,
1972 struct vm_area_struct * vma, unsigned long address,
1973 int write_access, pte_t *pte, pmd_t *pmd)
1974{
1975 pte_t entry;
1976
1977 entry = *pte;
1978 if (!pte_present(entry)) {
1979 /*
1980 * If it truly wasn't present, we know that kswapd
1981 * and the PTE updates will not touch it later. So
1982 * drop the lock.
1983 */
1984 if (pte_none(entry))
1985 return do_no_page(mm, vma, address, write_access, pte, pmd);
1986 if (pte_file(entry))
1987 return do_file_page(mm, vma, address, write_access, pte, pmd);
1988 return do_swap_page(mm, vma, address, pte, pmd, entry, write_access);
1989 }
1990
1991 if (write_access) {
1992 if (!pte_write(entry))
1993 return do_wp_page(mm, vma, address, pte, pmd, entry);
1994
1995 entry = pte_mkdirty(entry);
1996 }
1997 entry = pte_mkyoung(entry);
1998 ptep_set_access_flags(vma, address, pte, entry, write_access);
1999 update_mmu_cache(vma, address, entry);
2000 lazy_mmu_prot_update(entry);
2001 pte_unmap(pte);
2002 spin_unlock(&mm->page_table_lock);
2003 return VM_FAULT_MINOR;
2004}
2005
2006/*
2007 * By the time we get here, we already hold the mm semaphore
2008 */
2009int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
2010 unsigned long address, int write_access)
2011{
2012 pgd_t *pgd;
2013 pud_t *pud;
2014 pmd_t *pmd;
2015 pte_t *pte;
2016
2017 __set_current_state(TASK_RUNNING);
2018
2019 inc_page_state(pgfault);
2020
2021 if (is_vm_hugetlb_page(vma))
2022 return VM_FAULT_SIGBUS; /* mapping truncation does this. */
2023
2024 /*
2025 * We need the page table lock to synchronize with kswapd
2026 * and the SMP-safe atomic PTE updates.
2027 */
2028 pgd = pgd_offset(mm, address);
2029 spin_lock(&mm->page_table_lock);
2030
2031 pud = pud_alloc(mm, pgd, address);
2032 if (!pud)
2033 goto oom;
2034
2035 pmd = pmd_alloc(mm, pud, address);
2036 if (!pmd)
2037 goto oom;
2038
2039 pte = pte_alloc_map(mm, pmd, address);
2040 if (!pte)
2041 goto oom;
2042
2043 return handle_pte_fault(mm, vma, address, write_access, pte, pmd);
2044
2045 oom:
2046 spin_unlock(&mm->page_table_lock);
2047 return VM_FAULT_OOM;
2048}
2049
2050#ifndef __PAGETABLE_PUD_FOLDED
2051/*
2052 * Allocate page upper directory.
2053 *
2054 * We've already handled the fast-path in-line, and we own the
2055 * page table lock.
2056 */
2057pud_t fastcall *__pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2058{
2059 pud_t *new;
2060
2061 spin_unlock(&mm->page_table_lock);
2062 new = pud_alloc_one(mm, address);
2063 spin_lock(&mm->page_table_lock);
2064 if (!new)
2065 return NULL;
2066
2067 /*
2068 * Because we dropped the lock, we should re-check the
2069 * entry, as somebody else could have populated it..
2070 */
2071 if (pgd_present(*pgd)) {
2072 pud_free(new);
2073 goto out;
2074 }
2075 pgd_populate(mm, pgd, new);
2076 out:
2077 return pud_offset(pgd, address);
2078}
2079#endif /* __PAGETABLE_PUD_FOLDED */
2080
2081#ifndef __PAGETABLE_PMD_FOLDED
2082/*
2083 * Allocate page middle directory.
2084 *
2085 * We've already handled the fast-path in-line, and we own the
2086 * page table lock.
2087 */
2088pmd_t fastcall *__pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2089{
2090 pmd_t *new;
2091
2092 spin_unlock(&mm->page_table_lock);
2093 new = pmd_alloc_one(mm, address);
2094 spin_lock(&mm->page_table_lock);
2095 if (!new)
2096 return NULL;
2097
2098 /*
2099 * Because we dropped the lock, we should re-check the
2100 * entry, as somebody else could have populated it..
2101 */
2102#ifndef __ARCH_HAS_4LEVEL_HACK
2103 if (pud_present(*pud)) {
2104 pmd_free(new);
2105 goto out;
2106 }
2107 pud_populate(mm, pud, new);
2108#else
2109 if (pgd_present(*pud)) {
2110 pmd_free(new);
2111 goto out;
2112 }
2113 pgd_populate(mm, pud, new);
2114#endif /* __ARCH_HAS_4LEVEL_HACK */
2115
2116 out:
2117 return pmd_offset(pud, address);
2118}
2119#endif /* __PAGETABLE_PMD_FOLDED */
2120
2121int make_pages_present(unsigned long addr, unsigned long end)
2122{
2123 int ret, len, write;
2124 struct vm_area_struct * vma;
2125
2126 vma = find_vma(current->mm, addr);
2127 if (!vma)
2128 return -1;
2129 write = (vma->vm_flags & VM_WRITE) != 0;
2130 if (addr >= end)
2131 BUG();
2132 if (end > vma->vm_end)
2133 BUG();
2134 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2135 ret = get_user_pages(current, current->mm, addr,
2136 len, write, 0, NULL, NULL);
2137 if (ret < 0)
2138 return ret;
2139 return ret == len ? 0 : -1;
2140}
2141
2142/*
2143 * Map a vmalloc()-space virtual address to the physical page.
2144 */
2145struct page * vmalloc_to_page(void * vmalloc_addr)
2146{
2147 unsigned long addr = (unsigned long) vmalloc_addr;
2148 struct page *page = NULL;
2149 pgd_t *pgd = pgd_offset_k(addr);
2150 pud_t *pud;
2151 pmd_t *pmd;
2152 pte_t *ptep, pte;
2153
2154 if (!pgd_none(*pgd)) {
2155 pud = pud_offset(pgd, addr);
2156 if (!pud_none(*pud)) {
2157 pmd = pmd_offset(pud, addr);
2158 if (!pmd_none(*pmd)) {
2159 ptep = pte_offset_map(pmd, addr);
2160 pte = *ptep;
2161 if (pte_present(pte))
2162 page = pte_page(pte);
2163 pte_unmap(ptep);
2164 }
2165 }
2166 }
2167 return page;
2168}
2169
2170EXPORT_SYMBOL(vmalloc_to_page);
2171
2172/*
2173 * Map a vmalloc()-space virtual address to the physical page frame number.
2174 */
2175unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2176{
2177 return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2178}
2179
2180EXPORT_SYMBOL(vmalloc_to_pfn);
2181
2182/*
2183 * update_mem_hiwater
2184 * - update per process rss and vm high water data
2185 */
2186void update_mem_hiwater(struct task_struct *tsk)
2187{
2188 if (tsk->mm) {
2189 unsigned long rss = get_mm_counter(tsk->mm, rss);
2190
2191 if (tsk->mm->hiwater_rss < rss)
2192 tsk->mm->hiwater_rss = rss;
2193 if (tsk->mm->hiwater_vm < tsk->mm->total_vm)
2194 tsk->mm->hiwater_vm = tsk->mm->total_vm;
2195 }
2196}
2197
2198#if !defined(__HAVE_ARCH_GATE_AREA)
2199
2200#if defined(AT_SYSINFO_EHDR)
2201struct vm_area_struct gate_vma;
2202
2203static int __init gate_vma_init(void)
2204{
2205 gate_vma.vm_mm = NULL;
2206 gate_vma.vm_start = FIXADDR_USER_START;
2207 gate_vma.vm_end = FIXADDR_USER_END;
2208 gate_vma.vm_page_prot = PAGE_READONLY;
2209 gate_vma.vm_flags = 0;
2210 return 0;
2211}
2212__initcall(gate_vma_init);
2213#endif
2214
2215struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2216{
2217#ifdef AT_SYSINFO_EHDR
2218 return &gate_vma;
2219#else
2220 return NULL;
2221#endif
2222}
2223
2224int in_gate_area_no_task(unsigned long addr)
2225{
2226#ifdef AT_SYSINFO_EHDR
2227 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2228 return 1;
2229#endif
2230 return 0;
2231}
2232
2233#endif /* __HAVE_ARCH_GATE_AREA */