blob: d209f745db7fbc3154e83cf04666770068986724 [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}
843
844EXPORT_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
852static 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
860static inline int
861untouched_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
891int 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);
1017out:
1018 return i;
1019}
1020
1021EXPORT_SYMBOL(get_user_pages);
1022
1023static 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
1040static 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
1057static 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
1074int 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 + 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 */
1102static 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
1121static 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
1141static 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. */
1162int 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 + 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}
1196EXPORT_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 */
1204static 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 */
1214static 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 */
1246static 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
1329no_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
Hugh Dickinsee39b372005-04-19 13:29:15 -07001359 * large vma, note the restart_addr from unmap_vmas when it breaks out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 * 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
1368static 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
1379static 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
1386again:
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
Hugh Dickinsee39b372005-04-19 13:29:15 -07001397 restart_addr = zap_page_range(vma, start_addr,
1398 end_addr - start_addr, details);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
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
Hugh Dickinsee39b372005-04-19 13:29:15 -07001409 if (restart_addr >= end_addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 /* 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 */
Hugh Dickinsee39b372005-04-19 13:29:15 -07001416 vma->vm_truncate_count = restart_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 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
1427static 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
1434restart:
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
1459static 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 */
1470restart:
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 */
1498void 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}
1547EXPORT_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 */
1557int 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
1575do_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
1583out_truncate:
1584 if (inode->i_op && inode->i_op->truncate)
1585 inode->i_op->truncate(inode);
1586 return 0;
1587out_sig:
1588 send_sig(SIGXFSZ, current, 0);
1589out_big:
1590 return -EFBIG;
1591out_busy:
1592 return -ETXTBSY;
1593}
1594
1595EXPORT_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 */
1608void 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 */
1657static 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))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 ret = VM_FAULT_MINOR;
Kirill Korotaevb8107482005-05-16 21:53:50 -07001705 goto out_nomap;
1706 }
1707
1708 if (unlikely(!PageUptodate(page))) {
1709 ret = VM_FAULT_SIGBUS;
1710 goto out_nomap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 }
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);
1743out:
1744 return ret;
Kirill Korotaevb8107482005-05-16 21:53:50 -07001745out_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;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751}
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 */
1758static int
1759do_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);
1806out:
1807 return VM_FAULT_MINOR;
1808no_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 */
1824static int
1825do_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 }
1846retry:
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);
1932out:
1933 return ret;
1934oom:
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 */
1945static 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 */
1996static 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 */
2034int 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 */
2082pud_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 */
2113pmd_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
2146int 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 */
2170struct 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
2195EXPORT_SYMBOL(vmalloc_to_page);
2196
2197/*
2198 * Map a vmalloc()-space virtual address to the physical page frame number.
2199 */
2200unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2201{
2202 return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2203}
2204
2205EXPORT_SYMBOL(vmalloc_to_pfn);
2206
2207/*
2208 * update_mem_hiwater
2209 * - update per process rss and vm high water data
2210 */
2211void 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)
2226struct vm_area_struct gate_vma;
2227
2228static 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
2240struct 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
2249int 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 */