blob: 788a628103405e955a7d28f9935be690eb6d021a [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
Andy Whitcroftd41dee32005-06-23 00:07:54 -070061#ifndef CONFIG_NEED_MULTIPLE_NODES
Linus Torvalds1da177e2005-04-16 15:20:36 -070062/* 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
Nick Piggind9928952005-08-28 16:49:11 +1000501 /*
502 * Don't copy ptes where a page fault will fill them correctly.
503 * Fork becomes much lighter when there are big shared or private
504 * readonly mappings. The tradeoff is that copy_page_range is more
505 * efficient than faulting.
506 */
507 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_RESERVED))) {
508 if (!vma->anon_vma)
509 return 0;
510 }
511
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 if (is_vm_hugetlb_page(vma))
513 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
514
515 dst_pgd = pgd_offset(dst_mm, addr);
516 src_pgd = pgd_offset(src_mm, addr);
517 do {
518 next = pgd_addr_end(addr, end);
519 if (pgd_none_or_clear_bad(src_pgd))
520 continue;
521 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
522 vma, addr, next))
523 return -ENOMEM;
524 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
525 return 0;
526}
527
528static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
529 unsigned long addr, unsigned long end,
530 struct zap_details *details)
531{
532 pte_t *pte;
533
534 pte = pte_offset_map(pmd, addr);
535 do {
536 pte_t ptent = *pte;
537 if (pte_none(ptent))
538 continue;
539 if (pte_present(ptent)) {
540 struct page *page = NULL;
541 unsigned long pfn = pte_pfn(ptent);
542 if (pfn_valid(pfn)) {
543 page = pfn_to_page(pfn);
544 if (PageReserved(page))
545 page = NULL;
546 }
547 if (unlikely(details) && page) {
548 /*
549 * unmap_shared_mapping_pages() wants to
550 * invalidate cache without truncating:
551 * unmap shared but keep private pages.
552 */
553 if (details->check_mapping &&
554 details->check_mapping != page->mapping)
555 continue;
556 /*
557 * Each page->index must be checked when
558 * invalidating or truncating nonlinear.
559 */
560 if (details->nonlinear_vma &&
561 (page->index < details->first_index ||
562 page->index > details->last_index))
563 continue;
564 }
Zachary Amsdena6003882005-09-03 15:55:04 -0700565 ptent = ptep_get_and_clear_full(tlb->mm, addr, pte,
566 tlb->fullmm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 tlb_remove_tlb_entry(tlb, pte, addr);
568 if (unlikely(!page))
569 continue;
570 if (unlikely(details) && details->nonlinear_vma
571 && linear_page_index(details->nonlinear_vma,
572 addr) != page->index)
573 set_pte_at(tlb->mm, addr, pte,
574 pgoff_to_pte(page->index));
575 if (pte_dirty(ptent))
576 set_page_dirty(page);
577 if (PageAnon(page))
578 dec_mm_counter(tlb->mm, anon_rss);
579 else if (pte_young(ptent))
580 mark_page_accessed(page);
581 tlb->freed++;
582 page_remove_rmap(page);
583 tlb_remove_page(tlb, page);
584 continue;
585 }
586 /*
587 * If details->check_mapping, we leave swap entries;
588 * if details->nonlinear_vma, we leave file entries.
589 */
590 if (unlikely(details))
591 continue;
592 if (!pte_file(ptent))
593 free_swap_and_cache(pte_to_swp_entry(ptent));
Zachary Amsdena6003882005-09-03 15:55:04 -0700594 pte_clear_full(tlb->mm, addr, pte, tlb->fullmm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 } while (pte++, addr += PAGE_SIZE, addr != end);
596 pte_unmap(pte - 1);
597}
598
599static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud,
600 unsigned long addr, unsigned long end,
601 struct zap_details *details)
602{
603 pmd_t *pmd;
604 unsigned long next;
605
606 pmd = pmd_offset(pud, addr);
607 do {
608 next = pmd_addr_end(addr, end);
609 if (pmd_none_or_clear_bad(pmd))
610 continue;
611 zap_pte_range(tlb, pmd, addr, next, details);
612 } while (pmd++, addr = next, addr != end);
613}
614
615static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
616 unsigned long addr, unsigned long end,
617 struct zap_details *details)
618{
619 pud_t *pud;
620 unsigned long next;
621
622 pud = pud_offset(pgd, addr);
623 do {
624 next = pud_addr_end(addr, end);
625 if (pud_none_or_clear_bad(pud))
626 continue;
627 zap_pmd_range(tlb, pud, addr, next, details);
628 } while (pud++, addr = next, addr != end);
629}
630
631static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
632 unsigned long addr, unsigned long end,
633 struct zap_details *details)
634{
635 pgd_t *pgd;
636 unsigned long next;
637
638 if (details && !details->check_mapping && !details->nonlinear_vma)
639 details = NULL;
640
641 BUG_ON(addr >= end);
642 tlb_start_vma(tlb, vma);
643 pgd = pgd_offset(vma->vm_mm, addr);
644 do {
645 next = pgd_addr_end(addr, end);
646 if (pgd_none_or_clear_bad(pgd))
647 continue;
648 zap_pud_range(tlb, pgd, addr, next, details);
649 } while (pgd++, addr = next, addr != end);
650 tlb_end_vma(tlb, vma);
651}
652
653#ifdef CONFIG_PREEMPT
654# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
655#else
656/* No preempt: go for improved straight-line efficiency */
657# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
658#endif
659
660/**
661 * unmap_vmas - unmap a range of memory covered by a list of vma's
662 * @tlbp: address of the caller's struct mmu_gather
663 * @mm: the controlling mm_struct
664 * @vma: the starting vma
665 * @start_addr: virtual address at which to start unmapping
666 * @end_addr: virtual address at which to end unmapping
667 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
668 * @details: details of nonlinear truncation or shared cache invalidation
669 *
Hugh Dickinsee39b372005-04-19 13:29:15 -0700670 * Returns the end address of the unmapping (restart addr if interrupted).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 *
672 * Unmap all pages in the vma list. Called under page_table_lock.
673 *
674 * We aim to not hold page_table_lock for too long (for scheduling latency
675 * reasons). So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
676 * return the ending mmu_gather to the caller.
677 *
678 * Only addresses between `start' and `end' will be unmapped.
679 *
680 * The VMA list must be sorted in ascending virtual address order.
681 *
682 * unmap_vmas() assumes that the caller will flush the whole unmapped address
683 * range after unmap_vmas() returns. So the only responsibility here is to
684 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
685 * drops the lock and schedules.
686 */
Hugh Dickinsee39b372005-04-19 13:29:15 -0700687unsigned long unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 struct vm_area_struct *vma, unsigned long start_addr,
689 unsigned long end_addr, unsigned long *nr_accounted,
690 struct zap_details *details)
691{
692 unsigned long zap_bytes = ZAP_BLOCK_SIZE;
693 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
694 int tlb_start_valid = 0;
Hugh Dickinsee39b372005-04-19 13:29:15 -0700695 unsigned long start = start_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
697 int fullmm = tlb_is_full_mm(*tlbp);
698
699 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 unsigned long end;
701
702 start = max(vma->vm_start, start_addr);
703 if (start >= vma->vm_end)
704 continue;
705 end = min(vma->vm_end, end_addr);
706 if (end <= vma->vm_start)
707 continue;
708
709 if (vma->vm_flags & VM_ACCOUNT)
710 *nr_accounted += (end - start) >> PAGE_SHIFT;
711
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 while (start != end) {
713 unsigned long block;
714
715 if (!tlb_start_valid) {
716 tlb_start = start;
717 tlb_start_valid = 1;
718 }
719
720 if (is_vm_hugetlb_page(vma)) {
721 block = end - start;
722 unmap_hugepage_range(vma, start, end);
723 } else {
724 block = min(zap_bytes, end - start);
725 unmap_page_range(*tlbp, vma, start,
726 start + block, details);
727 }
728
729 start += block;
730 zap_bytes -= block;
731 if ((long)zap_bytes > 0)
732 continue;
733
734 tlb_finish_mmu(*tlbp, tlb_start, start);
735
736 if (need_resched() ||
737 need_lockbreak(&mm->page_table_lock) ||
738 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
739 if (i_mmap_lock) {
740 /* must reset count of rss freed */
741 *tlbp = tlb_gather_mmu(mm, fullmm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 goto out;
743 }
744 spin_unlock(&mm->page_table_lock);
745 cond_resched();
746 spin_lock(&mm->page_table_lock);
747 }
748
749 *tlbp = tlb_gather_mmu(mm, fullmm);
750 tlb_start_valid = 0;
751 zap_bytes = ZAP_BLOCK_SIZE;
752 }
753 }
754out:
Hugh Dickinsee39b372005-04-19 13:29:15 -0700755 return start; /* which is now the end (or restart) address */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756}
757
758/**
759 * zap_page_range - remove user pages in a given range
760 * @vma: vm_area_struct holding the applicable pages
761 * @address: starting address of pages to zap
762 * @size: number of bytes to zap
763 * @details: details of nonlinear truncation or shared cache invalidation
764 */
Hugh Dickinsee39b372005-04-19 13:29:15 -0700765unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 unsigned long size, struct zap_details *details)
767{
768 struct mm_struct *mm = vma->vm_mm;
769 struct mmu_gather *tlb;
770 unsigned long end = address + size;
771 unsigned long nr_accounted = 0;
772
773 if (is_vm_hugetlb_page(vma)) {
774 zap_hugepage_range(vma, address, size);
Hugh Dickinsee39b372005-04-19 13:29:15 -0700775 return end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 }
777
778 lru_add_drain();
779 spin_lock(&mm->page_table_lock);
780 tlb = tlb_gather_mmu(mm, 0);
Hugh Dickinsee39b372005-04-19 13:29:15 -0700781 end = unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 tlb_finish_mmu(tlb, address, end);
783 spin_unlock(&mm->page_table_lock);
Hugh Dickinsee39b372005-04-19 13:29:15 -0700784 return end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785}
786
787/*
788 * Do a quick page-table lookup for a single page.
789 * mm->page_table_lock must be held.
790 */
Andrew Morton1aaf18f2005-07-27 11:43:54 -0700791static struct page *__follow_page(struct mm_struct *mm, unsigned long address,
792 int read, int write, int accessed)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793{
794 pgd_t *pgd;
795 pud_t *pud;
796 pmd_t *pmd;
797 pte_t *ptep, pte;
798 unsigned long pfn;
799 struct page *page;
800
801 page = follow_huge_addr(mm, address, write);
802 if (! IS_ERR(page))
803 return page;
804
805 pgd = pgd_offset(mm, address);
806 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
807 goto out;
808
809 pud = pud_offset(pgd, address);
810 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
811 goto out;
812
813 pmd = pmd_offset(pud, address);
814 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
815 goto out;
816 if (pmd_huge(*pmd))
817 return follow_huge_pmd(mm, address, pmd, write);
818
819 ptep = pte_offset_map(pmd, address);
820 if (!ptep)
821 goto out;
822
823 pte = *ptep;
824 pte_unmap(ptep);
825 if (pte_present(pte)) {
Nick Pigginf33ea7f2005-08-03 20:24:01 +1000826 if (write && !pte_write(pte))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 goto out;
828 if (read && !pte_read(pte))
829 goto out;
830 pfn = pte_pfn(pte);
831 if (pfn_valid(pfn)) {
832 page = pfn_to_page(pfn);
Nick Pigginf33ea7f2005-08-03 20:24:01 +1000833 if (accessed) {
834 if (write && !pte_dirty(pte) &&!PageDirty(page))
835 set_page_dirty(page);
Andrew Morton1aaf18f2005-07-27 11:43:54 -0700836 mark_page_accessed(page);
Nick Pigginf33ea7f2005-08-03 20:24:01 +1000837 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 return page;
839 }
840 }
841
842out:
843 return NULL;
844}
845
Andrew Morton1aaf18f2005-07-27 11:43:54 -0700846inline struct page *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847follow_page(struct mm_struct *mm, unsigned long address, int write)
848{
Andrew Morton1aaf18f2005-07-27 11:43:54 -0700849 return __follow_page(mm, address, 0, write, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850}
851
Andrew Morton1aaf18f2005-07-27 11:43:54 -0700852/*
853 * check_user_page_readable() can be called frm niterrupt context by oprofile,
854 * so we need to avoid taking any non-irq-safe locks
855 */
856int check_user_page_readable(struct mm_struct *mm, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857{
Andrew Morton1aaf18f2005-07-27 11:43:54 -0700858 return __follow_page(mm, address, 1, 0, 0) != NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860EXPORT_SYMBOL(check_user_page_readable);
861
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862static inline int
863untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
864 unsigned long address)
865{
866 pgd_t *pgd;
867 pud_t *pud;
868 pmd_t *pmd;
869
870 /* Check if the vma is for an anonymous mapping. */
871 if (vma->vm_ops && vma->vm_ops->nopage)
872 return 0;
873
874 /* Check if page directory entry exists. */
875 pgd = pgd_offset(mm, address);
876 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
877 return 1;
878
879 pud = pud_offset(pgd, address);
880 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
881 return 1;
882
883 /* Check if page middle directory entry exists. */
884 pmd = pmd_offset(pud, address);
885 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
886 return 1;
887
888 /* There is a pte slot for 'address' in 'mm'. */
889 return 0;
890}
891
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
893 unsigned long start, int len, int write, int force,
894 struct page **pages, struct vm_area_struct **vmas)
895{
896 int i;
897 unsigned int flags;
898
899 /*
900 * Require read or write permissions.
901 * If 'force' is set, we only require the "MAY" flags.
902 */
903 flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
904 flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
905 i = 0;
906
907 do {
908 struct vm_area_struct * vma;
909
910 vma = find_extend_vma(mm, start);
911 if (!vma && in_gate_area(tsk, start)) {
912 unsigned long pg = start & PAGE_MASK;
913 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
914 pgd_t *pgd;
915 pud_t *pud;
916 pmd_t *pmd;
917 pte_t *pte;
918 if (write) /* user gate pages are read-only */
919 return i ? : -EFAULT;
920 if (pg > TASK_SIZE)
921 pgd = pgd_offset_k(pg);
922 else
923 pgd = pgd_offset_gate(mm, pg);
924 BUG_ON(pgd_none(*pgd));
925 pud = pud_offset(pgd, pg);
926 BUG_ON(pud_none(*pud));
927 pmd = pmd_offset(pud, pg);
Hugh Dickins690dbe12005-08-01 21:11:42 -0700928 if (pmd_none(*pmd))
929 return i ? : -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 pte = pte_offset_map(pmd, pg);
Hugh Dickins690dbe12005-08-01 21:11:42 -0700931 if (pte_none(*pte)) {
932 pte_unmap(pte);
933 return i ? : -EFAULT;
934 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935 if (pages) {
936 pages[i] = pte_page(*pte);
937 get_page(pages[i]);
938 }
939 pte_unmap(pte);
940 if (vmas)
941 vmas[i] = gate_vma;
942 i++;
943 start += PAGE_SIZE;
944 len--;
945 continue;
946 }
947
948 if (!vma || (vma->vm_flags & VM_IO)
949 || !(flags & vma->vm_flags))
950 return i ? : -EFAULT;
951
952 if (is_vm_hugetlb_page(vma)) {
953 i = follow_hugetlb_page(mm, vma, pages, vmas,
954 &start, &len, i);
955 continue;
956 }
957 spin_lock(&mm->page_table_lock);
958 do {
Nick Pigginf33ea7f2005-08-03 20:24:01 +1000959 int write_access = write;
Hugh Dickins08ef4722005-06-21 17:15:10 -0700960 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
962 cond_resched_lock(&mm->page_table_lock);
Nick Pigginf33ea7f2005-08-03 20:24:01 +1000963 while (!(page = follow_page(mm, start, write_access))) {
Linus Torvaldsa68d2eb2005-08-03 10:07:09 -0700964 int ret;
965
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 /*
967 * Shortcut for anonymous pages. We don't want
968 * to force the creation of pages tables for
Hugh Dickins08ef4722005-06-21 17:15:10 -0700969 * insanely big anonymously mapped areas that
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 * nobody touched so far. This is important
971 * for doing a core dump for these mappings.
972 */
Linus Torvalds4ceb5db2005-08-01 11:14:49 -0700973 if (!write && untouched_anonymous_page(mm,vma,start)) {
Hugh Dickins08ef4722005-06-21 17:15:10 -0700974 page = ZERO_PAGE(start);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 break;
976 }
977 spin_unlock(&mm->page_table_lock);
Linus Torvaldsa68d2eb2005-08-03 10:07:09 -0700978 ret = __handle_mm_fault(mm, vma, start, write_access);
979
980 /*
981 * The VM_FAULT_WRITE bit tells us that do_wp_page has
982 * broken COW when necessary, even if maybe_mkwrite
983 * decided not to set pte_write. We can thus safely do
984 * subsequent page lookups as if they were reads.
985 */
986 if (ret & VM_FAULT_WRITE)
Nick Pigginf33ea7f2005-08-03 20:24:01 +1000987 write_access = 0;
Linus Torvaldsa68d2eb2005-08-03 10:07:09 -0700988
989 switch (ret & ~VM_FAULT_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 case VM_FAULT_MINOR:
991 tsk->min_flt++;
992 break;
993 case VM_FAULT_MAJOR:
994 tsk->maj_flt++;
995 break;
996 case VM_FAULT_SIGBUS:
997 return i ? i : -EFAULT;
998 case VM_FAULT_OOM:
999 return i ? i : -ENOMEM;
1000 default:
1001 BUG();
1002 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 spin_lock(&mm->page_table_lock);
1004 }
1005 if (pages) {
Hugh Dickins08ef4722005-06-21 17:15:10 -07001006 pages[i] = page;
1007 flush_dcache_page(page);
1008 if (!PageReserved(page))
1009 page_cache_get(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 }
1011 if (vmas)
1012 vmas[i] = vma;
1013 i++;
1014 start += PAGE_SIZE;
1015 len--;
Hugh Dickins08ef4722005-06-21 17:15:10 -07001016 } while (len && start < vma->vm_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 spin_unlock(&mm->page_table_lock);
Hugh Dickins08ef4722005-06-21 17:15:10 -07001018 } while (len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001019 return i;
1020}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021EXPORT_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;
Hugh Dickins2d15cab2005-06-25 14:54:33 -07001167 unsigned long end = addr + PAGE_ALIGN(size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168 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;
Nick Pigginf33ea7f2005-08-03 20:24:01 +10001252 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253
1254 if (unlikely(!pfn_valid(pfn))) {
1255 /*
1256 * This should really halt the system so it can be debugged or
1257 * at least the kernel stops what it's doing before it corrupts
1258 * data, but for the moment just pretend this is OOM.
1259 */
1260 pte_unmap(page_table);
1261 printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n",
1262 address);
1263 spin_unlock(&mm->page_table_lock);
1264 return VM_FAULT_OOM;
1265 }
1266 old_page = pfn_to_page(pfn);
1267
Hugh Dickinsd296e9c2005-06-21 17:15:11 -07001268 if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 int reuse = can_share_swap_page(old_page);
1270 unlock_page(old_page);
1271 if (reuse) {
1272 flush_cache_page(vma, address, pfn);
1273 entry = maybe_mkwrite(pte_mkyoung(pte_mkdirty(pte)),
1274 vma);
1275 ptep_set_access_flags(vma, address, page_table, entry, 1);
1276 update_mmu_cache(vma, address, entry);
1277 lazy_mmu_prot_update(entry);
1278 pte_unmap(page_table);
1279 spin_unlock(&mm->page_table_lock);
Nick Pigginf33ea7f2005-08-03 20:24:01 +10001280 return VM_FAULT_MINOR|VM_FAULT_WRITE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281 }
1282 }
1283 pte_unmap(page_table);
1284
1285 /*
1286 * Ok, we need to copy. Oh, well..
1287 */
1288 if (!PageReserved(old_page))
1289 page_cache_get(old_page);
1290 spin_unlock(&mm->page_table_lock);
1291
1292 if (unlikely(anon_vma_prepare(vma)))
1293 goto no_new_page;
1294 if (old_page == ZERO_PAGE(address)) {
1295 new_page = alloc_zeroed_user_highpage(vma, address);
1296 if (!new_page)
1297 goto no_new_page;
1298 } else {
1299 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1300 if (!new_page)
1301 goto no_new_page;
1302 copy_user_highpage(new_page, old_page, address);
1303 }
1304 /*
1305 * Re-check the pte - we dropped the lock
1306 */
Nick Pigginf33ea7f2005-08-03 20:24:01 +10001307 ret = VM_FAULT_MINOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 spin_lock(&mm->page_table_lock);
1309 page_table = pte_offset_map(pmd, address);
1310 if (likely(pte_same(*page_table, pte))) {
1311 if (PageAnon(old_page))
1312 dec_mm_counter(mm, anon_rss);
1313 if (PageReserved(old_page))
1314 inc_mm_counter(mm, rss);
1315 else
1316 page_remove_rmap(old_page);
1317 flush_cache_page(vma, address, pfn);
1318 break_cow(vma, new_page, address, page_table);
1319 lru_cache_add_active(new_page);
1320 page_add_anon_rmap(new_page, vma, address);
1321
1322 /* Free the old page.. */
1323 new_page = old_page;
Nick Pigginf33ea7f2005-08-03 20:24:01 +10001324 ret |= VM_FAULT_WRITE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 }
1326 pte_unmap(page_table);
1327 page_cache_release(new_page);
1328 page_cache_release(old_page);
1329 spin_unlock(&mm->page_table_lock);
Nick Pigginf33ea7f2005-08-03 20:24:01 +10001330 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331
1332no_new_page:
1333 page_cache_release(old_page);
1334 return VM_FAULT_OOM;
1335}
1336
1337/*
1338 * Helper functions for unmap_mapping_range().
1339 *
1340 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1341 *
1342 * We have to restart searching the prio_tree whenever we drop the lock,
1343 * since the iterator is only valid while the lock is held, and anyway
1344 * a later vma might be split and reinserted earlier while lock dropped.
1345 *
1346 * The list of nonlinear vmas could be handled more efficiently, using
1347 * a placeholder, but handle it in the same way until a need is shown.
1348 * It is important to search the prio_tree before nonlinear list: a vma
1349 * may become nonlinear and be shifted from prio_tree to nonlinear list
1350 * while the lock is dropped; but never shifted from list to prio_tree.
1351 *
1352 * In order to make forward progress despite restarting the search,
1353 * vm_truncate_count is used to mark a vma as now dealt with, so we can
1354 * quickly skip it next time around. Since the prio_tree search only
1355 * shows us those vmas affected by unmapping the range in question, we
1356 * can't efficiently keep all vmas in step with mapping->truncate_count:
1357 * so instead reset them all whenever it wraps back to 0 (then go to 1).
1358 * mapping->truncate_count and vma->vm_truncate_count are protected by
1359 * i_mmap_lock.
1360 *
1361 * In order to make forward progress despite repeatedly restarting some
Hugh Dickinsee39b372005-04-19 13:29:15 -07001362 * large vma, note the restart_addr from unmap_vmas when it breaks out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 * and restart from that address when we reach that vma again. It might
1364 * have been split or merged, shrunk or extended, but never shifted: so
1365 * restart_addr remains valid so long as it remains in the vma's range.
1366 * unmap_mapping_range forces truncate_count to leap over page-aligned
1367 * values so we can save vma's restart_addr in its truncate_count field.
1368 */
1369#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1370
1371static void reset_vma_truncate_counts(struct address_space *mapping)
1372{
1373 struct vm_area_struct *vma;
1374 struct prio_tree_iter iter;
1375
1376 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1377 vma->vm_truncate_count = 0;
1378 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1379 vma->vm_truncate_count = 0;
1380}
1381
1382static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1383 unsigned long start_addr, unsigned long end_addr,
1384 struct zap_details *details)
1385{
1386 unsigned long restart_addr;
1387 int need_break;
1388
1389again:
1390 restart_addr = vma->vm_truncate_count;
1391 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1392 start_addr = restart_addr;
1393 if (start_addr >= end_addr) {
1394 /* Top of vma has been split off since last time */
1395 vma->vm_truncate_count = details->truncate_count;
1396 return 0;
1397 }
1398 }
1399
Hugh Dickinsee39b372005-04-19 13:29:15 -07001400 restart_addr = zap_page_range(vma, start_addr,
1401 end_addr - start_addr, details);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402
1403 /*
1404 * We cannot rely on the break test in unmap_vmas:
1405 * on the one hand, we don't want to restart our loop
1406 * just because that broke out for the page_table_lock;
1407 * on the other hand, it does no test when vma is small.
1408 */
1409 need_break = need_resched() ||
1410 need_lockbreak(details->i_mmap_lock);
1411
Hugh Dickinsee39b372005-04-19 13:29:15 -07001412 if (restart_addr >= end_addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 /* We have now completed this vma: mark it so */
1414 vma->vm_truncate_count = details->truncate_count;
1415 if (!need_break)
1416 return 0;
1417 } else {
1418 /* Note restart_addr in vma's truncate_count field */
Hugh Dickinsee39b372005-04-19 13:29:15 -07001419 vma->vm_truncate_count = restart_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 if (!need_break)
1421 goto again;
1422 }
1423
1424 spin_unlock(details->i_mmap_lock);
1425 cond_resched();
1426 spin_lock(details->i_mmap_lock);
1427 return -EINTR;
1428}
1429
1430static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1431 struct zap_details *details)
1432{
1433 struct vm_area_struct *vma;
1434 struct prio_tree_iter iter;
1435 pgoff_t vba, vea, zba, zea;
1436
1437restart:
1438 vma_prio_tree_foreach(vma, &iter, root,
1439 details->first_index, details->last_index) {
1440 /* Skip quickly over those we have already dealt with */
1441 if (vma->vm_truncate_count == details->truncate_count)
1442 continue;
1443
1444 vba = vma->vm_pgoff;
1445 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1446 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1447 zba = details->first_index;
1448 if (zba < vba)
1449 zba = vba;
1450 zea = details->last_index;
1451 if (zea > vea)
1452 zea = vea;
1453
1454 if (unmap_mapping_range_vma(vma,
1455 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1456 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1457 details) < 0)
1458 goto restart;
1459 }
1460}
1461
1462static inline void unmap_mapping_range_list(struct list_head *head,
1463 struct zap_details *details)
1464{
1465 struct vm_area_struct *vma;
1466
1467 /*
1468 * In nonlinear VMAs there is no correspondence between virtual address
1469 * offset and file offset. So we must perform an exhaustive search
1470 * across *all* the pages in each nonlinear VMA, not just the pages
1471 * whose virtual address lies outside the file truncation point.
1472 */
1473restart:
1474 list_for_each_entry(vma, head, shared.vm_set.list) {
1475 /* Skip quickly over those we have already dealt with */
1476 if (vma->vm_truncate_count == details->truncate_count)
1477 continue;
1478 details->nonlinear_vma = vma;
1479 if (unmap_mapping_range_vma(vma, vma->vm_start,
1480 vma->vm_end, details) < 0)
1481 goto restart;
1482 }
1483}
1484
1485/**
1486 * unmap_mapping_range - unmap the portion of all mmaps
1487 * in the specified address_space corresponding to the specified
1488 * page range in the underlying file.
Martin Waitz3d410882005-06-23 22:05:21 -07001489 * @mapping: the address space containing mmaps to be unmapped.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 * @holebegin: byte in first page to unmap, relative to the start of
1491 * the underlying file. This will be rounded down to a PAGE_SIZE
1492 * boundary. Note that this is different from vmtruncate(), which
1493 * must keep the partial page. In contrast, we must get rid of
1494 * partial pages.
1495 * @holelen: size of prospective hole in bytes. This will be rounded
1496 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
1497 * end of the file.
1498 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1499 * but 0 when invalidating pagecache, don't throw away private data.
1500 */
1501void unmap_mapping_range(struct address_space *mapping,
1502 loff_t const holebegin, loff_t const holelen, int even_cows)
1503{
1504 struct zap_details details;
1505 pgoff_t hba = holebegin >> PAGE_SHIFT;
1506 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1507
1508 /* Check for overflow. */
1509 if (sizeof(holelen) > sizeof(hlen)) {
1510 long long holeend =
1511 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1512 if (holeend & ~(long long)ULONG_MAX)
1513 hlen = ULONG_MAX - hba + 1;
1514 }
1515
1516 details.check_mapping = even_cows? NULL: mapping;
1517 details.nonlinear_vma = NULL;
1518 details.first_index = hba;
1519 details.last_index = hba + hlen - 1;
1520 if (details.last_index < details.first_index)
1521 details.last_index = ULONG_MAX;
1522 details.i_mmap_lock = &mapping->i_mmap_lock;
1523
1524 spin_lock(&mapping->i_mmap_lock);
1525
1526 /* serialize i_size write against truncate_count write */
1527 smp_wmb();
1528 /* Protect against page faults, and endless unmapping loops */
1529 mapping->truncate_count++;
1530 /*
1531 * For archs where spin_lock has inclusive semantics like ia64
1532 * this smp_mb() will prevent to read pagetable contents
1533 * before the truncate_count increment is visible to
1534 * other cpus.
1535 */
1536 smp_mb();
1537 if (unlikely(is_restart_addr(mapping->truncate_count))) {
1538 if (mapping->truncate_count == 0)
1539 reset_vma_truncate_counts(mapping);
1540 mapping->truncate_count++;
1541 }
1542 details.truncate_count = mapping->truncate_count;
1543
1544 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1545 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1546 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1547 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1548 spin_unlock(&mapping->i_mmap_lock);
1549}
1550EXPORT_SYMBOL(unmap_mapping_range);
1551
1552/*
1553 * Handle all mappings that got truncated by a "truncate()"
1554 * system call.
1555 *
1556 * NOTE! We have to be ready to update the memory sharing
1557 * between the file and the memory map for a potential last
1558 * incomplete page. Ugly, but necessary.
1559 */
1560int vmtruncate(struct inode * inode, loff_t offset)
1561{
1562 struct address_space *mapping = inode->i_mapping;
1563 unsigned long limit;
1564
1565 if (inode->i_size < offset)
1566 goto do_expand;
1567 /*
1568 * truncation of in-use swapfiles is disallowed - it would cause
1569 * subsequent swapout to scribble on the now-freed blocks.
1570 */
1571 if (IS_SWAPFILE(inode))
1572 goto out_busy;
1573 i_size_write(inode, offset);
1574 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1575 truncate_inode_pages(mapping, offset);
1576 goto out_truncate;
1577
1578do_expand:
1579 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1580 if (limit != RLIM_INFINITY && offset > limit)
1581 goto out_sig;
1582 if (offset > inode->i_sb->s_maxbytes)
1583 goto out_big;
1584 i_size_write(inode, offset);
1585
1586out_truncate:
1587 if (inode->i_op && inode->i_op->truncate)
1588 inode->i_op->truncate(inode);
1589 return 0;
1590out_sig:
1591 send_sig(SIGXFSZ, current, 0);
1592out_big:
1593 return -EFBIG;
1594out_busy:
1595 return -ETXTBSY;
1596}
1597
1598EXPORT_SYMBOL(vmtruncate);
1599
1600/*
1601 * Primitive swap readahead code. We simply read an aligned block of
1602 * (1 << page_cluster) entries in the swap area. This method is chosen
1603 * because it doesn't cost us any seek time. We also make sure to queue
1604 * the 'original' request together with the readahead ones...
1605 *
1606 * This has been extended to use the NUMA policies from the mm triggering
1607 * the readahead.
1608 *
1609 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1610 */
1611void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1612{
1613#ifdef CONFIG_NUMA
1614 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1615#endif
1616 int i, num;
1617 struct page *new_page;
1618 unsigned long offset;
1619
1620 /*
1621 * Get the number of handles we should do readahead io to.
1622 */
1623 num = valid_swaphandles(entry, &offset);
1624 for (i = 0; i < num; offset++, i++) {
1625 /* Ok, do the async read-ahead now */
1626 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1627 offset), vma, addr);
1628 if (!new_page)
1629 break;
1630 page_cache_release(new_page);
1631#ifdef CONFIG_NUMA
1632 /*
1633 * Find the next applicable VMA for the NUMA policy.
1634 */
1635 addr += PAGE_SIZE;
1636 if (addr == 0)
1637 vma = NULL;
1638 if (vma) {
1639 if (addr >= vma->vm_end) {
1640 vma = next_vma;
1641 next_vma = vma ? vma->vm_next : NULL;
1642 }
1643 if (vma && addr < vma->vm_start)
1644 vma = NULL;
1645 } else {
1646 if (next_vma && addr >= next_vma->vm_start) {
1647 vma = next_vma;
1648 next_vma = vma->vm_next;
1649 }
1650 }
1651#endif
1652 }
1653 lru_add_drain(); /* Push any new pages onto the LRU now */
1654}
1655
1656/*
1657 * We hold the mm semaphore and the page_table_lock on entry and
1658 * should release the pagetable lock on exit..
1659 */
1660static int do_swap_page(struct mm_struct * mm,
1661 struct vm_area_struct * vma, unsigned long address,
1662 pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access)
1663{
1664 struct page *page;
1665 swp_entry_t entry = pte_to_swp_entry(orig_pte);
1666 pte_t pte;
1667 int ret = VM_FAULT_MINOR;
1668
1669 pte_unmap(page_table);
1670 spin_unlock(&mm->page_table_lock);
1671 page = lookup_swap_cache(entry);
1672 if (!page) {
1673 swapin_readahead(entry, address, vma);
1674 page = read_swap_cache_async(entry, vma, address);
1675 if (!page) {
1676 /*
1677 * Back out if somebody else faulted in this pte while
1678 * we released the page table lock.
1679 */
1680 spin_lock(&mm->page_table_lock);
1681 page_table = pte_offset_map(pmd, address);
1682 if (likely(pte_same(*page_table, orig_pte)))
1683 ret = VM_FAULT_OOM;
1684 else
1685 ret = VM_FAULT_MINOR;
1686 pte_unmap(page_table);
1687 spin_unlock(&mm->page_table_lock);
1688 goto out;
1689 }
1690
1691 /* Had to read the page from swap area: Major fault */
1692 ret = VM_FAULT_MAJOR;
1693 inc_page_state(pgmajfault);
1694 grab_swap_token();
1695 }
1696
1697 mark_page_accessed(page);
1698 lock_page(page);
1699
1700 /*
1701 * Back out if somebody else faulted in this pte while we
1702 * released the page table lock.
1703 */
1704 spin_lock(&mm->page_table_lock);
1705 page_table = pte_offset_map(pmd, address);
1706 if (unlikely(!pte_same(*page_table, orig_pte))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 ret = VM_FAULT_MINOR;
Kirill Korotaevb8107482005-05-16 21:53:50 -07001708 goto out_nomap;
1709 }
1710
1711 if (unlikely(!PageUptodate(page))) {
1712 ret = VM_FAULT_SIGBUS;
1713 goto out_nomap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714 }
1715
1716 /* The page isn't present yet, go ahead with the fault. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717
1718 inc_mm_counter(mm, rss);
1719 pte = mk_pte(page, vma->vm_page_prot);
1720 if (write_access && can_share_swap_page(page)) {
1721 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1722 write_access = 0;
1723 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724
1725 flush_icache_page(vma, page);
1726 set_pte_at(mm, address, page_table, pte);
1727 page_add_anon_rmap(page, vma, address);
1728
Hugh Dickinsc475a8a2005-06-21 17:15:12 -07001729 swap_free(entry);
1730 if (vm_swap_full())
1731 remove_exclusive_swap_page(page);
1732 unlock_page(page);
1733
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734 if (write_access) {
1735 if (do_wp_page(mm, vma, address,
1736 page_table, pmd, pte) == VM_FAULT_OOM)
1737 ret = VM_FAULT_OOM;
1738 goto out;
1739 }
1740
1741 /* No need to invalidate - it was non-present before */
1742 update_mmu_cache(vma, address, pte);
1743 lazy_mmu_prot_update(pte);
1744 pte_unmap(page_table);
1745 spin_unlock(&mm->page_table_lock);
1746out:
1747 return ret;
Kirill Korotaevb8107482005-05-16 21:53:50 -07001748out_nomap:
1749 pte_unmap(page_table);
1750 spin_unlock(&mm->page_table_lock);
1751 unlock_page(page);
1752 page_cache_release(page);
1753 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754}
1755
1756/*
1757 * We are called with the MM semaphore and page_table_lock
1758 * spinlock held to protect against concurrent faults in
1759 * multithreaded programs.
1760 */
1761static int
1762do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
1763 pte_t *page_table, pmd_t *pmd, int write_access,
1764 unsigned long addr)
1765{
1766 pte_t entry;
1767 struct page * page = ZERO_PAGE(addr);
1768
1769 /* Read-only mapping of ZERO_PAGE. */
1770 entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot));
1771
1772 /* ..except if it's a write access */
1773 if (write_access) {
1774 /* Allocate our own private page. */
1775 pte_unmap(page_table);
1776 spin_unlock(&mm->page_table_lock);
1777
1778 if (unlikely(anon_vma_prepare(vma)))
1779 goto no_mem;
1780 page = alloc_zeroed_user_highpage(vma, addr);
1781 if (!page)
1782 goto no_mem;
1783
1784 spin_lock(&mm->page_table_lock);
1785 page_table = pte_offset_map(pmd, addr);
1786
1787 if (!pte_none(*page_table)) {
1788 pte_unmap(page_table);
1789 page_cache_release(page);
1790 spin_unlock(&mm->page_table_lock);
1791 goto out;
1792 }
1793 inc_mm_counter(mm, rss);
1794 entry = maybe_mkwrite(pte_mkdirty(mk_pte(page,
1795 vma->vm_page_prot)),
1796 vma);
1797 lru_cache_add_active(page);
1798 SetPageReferenced(page);
1799 page_add_anon_rmap(page, vma, addr);
1800 }
1801
1802 set_pte_at(mm, addr, page_table, entry);
1803 pte_unmap(page_table);
1804
1805 /* No need to invalidate - it was non-present before */
1806 update_mmu_cache(vma, addr, entry);
1807 lazy_mmu_prot_update(entry);
1808 spin_unlock(&mm->page_table_lock);
1809out:
1810 return VM_FAULT_MINOR;
1811no_mem:
1812 return VM_FAULT_OOM;
1813}
1814
1815/*
1816 * do_no_page() tries to create a new page mapping. It aggressively
1817 * tries to share with existing pages, but makes a separate copy if
1818 * the "write_access" parameter is true in order to avoid the next
1819 * page fault.
1820 *
1821 * As this is called only for pages that do not currently exist, we
1822 * do not need to flush old virtual caches or the TLB.
1823 *
1824 * This is called with the MM semaphore held and the page table
1825 * spinlock held. Exit with the spinlock released.
1826 */
1827static int
1828do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1829 unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd)
1830{
1831 struct page * new_page;
1832 struct address_space *mapping = NULL;
1833 pte_t entry;
1834 unsigned int sequence = 0;
1835 int ret = VM_FAULT_MINOR;
1836 int anon = 0;
1837
1838 if (!vma->vm_ops || !vma->vm_ops->nopage)
1839 return do_anonymous_page(mm, vma, page_table,
1840 pmd, write_access, address);
1841 pte_unmap(page_table);
1842 spin_unlock(&mm->page_table_lock);
1843
1844 if (vma->vm_file) {
1845 mapping = vma->vm_file->f_mapping;
1846 sequence = mapping->truncate_count;
1847 smp_rmb(); /* serializes i_size against truncate_count */
1848 }
1849retry:
1850 cond_resched();
1851 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
1852 /*
1853 * No smp_rmb is needed here as long as there's a full
1854 * spin_lock/unlock sequence inside the ->nopage callback
1855 * (for the pagecache lookup) that acts as an implicit
1856 * smp_mb() and prevents the i_size read to happen
1857 * after the next truncate_count read.
1858 */
1859
1860 /* no page was available -- either SIGBUS or OOM */
1861 if (new_page == NOPAGE_SIGBUS)
1862 return VM_FAULT_SIGBUS;
1863 if (new_page == NOPAGE_OOM)
1864 return VM_FAULT_OOM;
1865
1866 /*
1867 * Should we do an early C-O-W break?
1868 */
1869 if (write_access && !(vma->vm_flags & VM_SHARED)) {
1870 struct page *page;
1871
1872 if (unlikely(anon_vma_prepare(vma)))
1873 goto oom;
1874 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1875 if (!page)
1876 goto oom;
1877 copy_user_highpage(page, new_page, address);
1878 page_cache_release(new_page);
1879 new_page = page;
1880 anon = 1;
1881 }
1882
1883 spin_lock(&mm->page_table_lock);
1884 /*
1885 * For a file-backed vma, someone could have truncated or otherwise
1886 * invalidated this page. If unmap_mapping_range got called,
1887 * retry getting the page.
1888 */
1889 if (mapping && unlikely(sequence != mapping->truncate_count)) {
1890 sequence = mapping->truncate_count;
1891 spin_unlock(&mm->page_table_lock);
1892 page_cache_release(new_page);
1893 goto retry;
1894 }
1895 page_table = pte_offset_map(pmd, address);
1896
1897 /*
1898 * This silly early PAGE_DIRTY setting removes a race
1899 * due to the bad i386 page protection. But it's valid
1900 * for other architectures too.
1901 *
1902 * Note that if write_access is true, we either now have
1903 * an exclusive copy of the page, or this is a shared mapping,
1904 * so we can make it writable and dirty to avoid having to
1905 * handle that later.
1906 */
1907 /* Only go through if we didn't race with anybody else... */
1908 if (pte_none(*page_table)) {
1909 if (!PageReserved(new_page))
1910 inc_mm_counter(mm, rss);
1911
1912 flush_icache_page(vma, new_page);
1913 entry = mk_pte(new_page, vma->vm_page_prot);
1914 if (write_access)
1915 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1916 set_pte_at(mm, address, page_table, entry);
1917 if (anon) {
1918 lru_cache_add_active(new_page);
1919 page_add_anon_rmap(new_page, vma, address);
1920 } else
1921 page_add_file_rmap(new_page);
1922 pte_unmap(page_table);
1923 } else {
1924 /* One of our sibling threads was faster, back out. */
1925 pte_unmap(page_table);
1926 page_cache_release(new_page);
1927 spin_unlock(&mm->page_table_lock);
1928 goto out;
1929 }
1930
1931 /* no need to invalidate: a not-present page shouldn't be cached */
1932 update_mmu_cache(vma, address, entry);
1933 lazy_mmu_prot_update(entry);
1934 spin_unlock(&mm->page_table_lock);
1935out:
1936 return ret;
1937oom:
1938 page_cache_release(new_page);
1939 ret = VM_FAULT_OOM;
1940 goto out;
1941}
1942
1943/*
1944 * Fault of a previously existing named mapping. Repopulate the pte
1945 * from the encoded file_pte if possible. This enables swappable
1946 * nonlinear vmas.
1947 */
1948static int do_file_page(struct mm_struct * mm, struct vm_area_struct * vma,
1949 unsigned long address, int write_access, pte_t *pte, pmd_t *pmd)
1950{
1951 unsigned long pgoff;
1952 int err;
1953
1954 BUG_ON(!vma->vm_ops || !vma->vm_ops->nopage);
1955 /*
1956 * Fall back to the linear mapping if the fs does not support
1957 * ->populate:
1958 */
Paolo 'Blaisorblade' Giarrusso4944e762005-09-03 15:54:56 -07001959 if (!vma->vm_ops->populate ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960 (write_access && !(vma->vm_flags & VM_SHARED))) {
1961 pte_clear(mm, address, pte);
1962 return do_no_page(mm, vma, address, write_access, pte, pmd);
1963 }
1964
1965 pgoff = pte_to_pgoff(*pte);
1966
1967 pte_unmap(pte);
1968 spin_unlock(&mm->page_table_lock);
1969
1970 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, vma->vm_page_prot, pgoff, 0);
1971 if (err == -ENOMEM)
1972 return VM_FAULT_OOM;
1973 if (err)
1974 return VM_FAULT_SIGBUS;
1975 return VM_FAULT_MAJOR;
1976}
1977
1978/*
1979 * These routines also need to handle stuff like marking pages dirty
1980 * and/or accessed for architectures that don't do it in hardware (most
1981 * RISC architectures). The early dirtying is also good on the i386.
1982 *
1983 * There is also a hook called "update_mmu_cache()" that architectures
1984 * with external mmu caches can use to update those (ie the Sparc or
1985 * PowerPC hashed page tables that act as extended TLBs).
1986 *
1987 * Note the "page_table_lock". It is to protect against kswapd removing
1988 * pages from under us. Note that kswapd only ever _removes_ pages, never
1989 * adds them. As such, once we have noticed that the page is not present,
1990 * we can drop the lock early.
1991 *
1992 * The adding of pages is protected by the MM semaphore (which we hold),
1993 * so we don't need to worry about a page being suddenly been added into
1994 * our VM.
1995 *
1996 * We enter with the pagetable spinlock held, we are supposed to
1997 * release it when done.
1998 */
1999static inline int handle_pte_fault(struct mm_struct *mm,
2000 struct vm_area_struct * vma, unsigned long address,
2001 int write_access, pte_t *pte, pmd_t *pmd)
2002{
2003 pte_t entry;
2004
2005 entry = *pte;
2006 if (!pte_present(entry)) {
2007 /*
2008 * If it truly wasn't present, we know that kswapd
2009 * and the PTE updates will not touch it later. So
2010 * drop the lock.
2011 */
2012 if (pte_none(entry))
2013 return do_no_page(mm, vma, address, write_access, pte, pmd);
2014 if (pte_file(entry))
2015 return do_file_page(mm, vma, address, write_access, pte, pmd);
2016 return do_swap_page(mm, vma, address, pte, pmd, entry, write_access);
2017 }
2018
2019 if (write_access) {
2020 if (!pte_write(entry))
2021 return do_wp_page(mm, vma, address, pte, pmd, entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022 entry = pte_mkdirty(entry);
2023 }
2024 entry = pte_mkyoung(entry);
2025 ptep_set_access_flags(vma, address, pte, entry, write_access);
2026 update_mmu_cache(vma, address, entry);
2027 lazy_mmu_prot_update(entry);
2028 pte_unmap(pte);
2029 spin_unlock(&mm->page_table_lock);
2030 return VM_FAULT_MINOR;
2031}
2032
2033/*
2034 * By the time we get here, we already hold the mm semaphore
2035 */
Nick Pigginf33ea7f2005-08-03 20:24:01 +10002036int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037 unsigned long address, int write_access)
2038{
2039 pgd_t *pgd;
2040 pud_t *pud;
2041 pmd_t *pmd;
2042 pte_t *pte;
2043
2044 __set_current_state(TASK_RUNNING);
2045
2046 inc_page_state(pgfault);
2047
2048 if (is_vm_hugetlb_page(vma))
2049 return VM_FAULT_SIGBUS; /* mapping truncation does this. */
2050
2051 /*
2052 * We need the page table lock to synchronize with kswapd
2053 * and the SMP-safe atomic PTE updates.
2054 */
2055 pgd = pgd_offset(mm, address);
2056 spin_lock(&mm->page_table_lock);
2057
2058 pud = pud_alloc(mm, pgd, address);
2059 if (!pud)
2060 goto oom;
2061
2062 pmd = pmd_alloc(mm, pud, address);
2063 if (!pmd)
2064 goto oom;
2065
2066 pte = pte_alloc_map(mm, pmd, address);
2067 if (!pte)
2068 goto oom;
2069
2070 return handle_pte_fault(mm, vma, address, write_access, pte, pmd);
2071
2072 oom:
2073 spin_unlock(&mm->page_table_lock);
2074 return VM_FAULT_OOM;
2075}
2076
2077#ifndef __PAGETABLE_PUD_FOLDED
2078/*
2079 * Allocate page upper directory.
2080 *
2081 * We've already handled the fast-path in-line, and we own the
2082 * page table lock.
2083 */
2084pud_t fastcall *__pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2085{
2086 pud_t *new;
2087
2088 spin_unlock(&mm->page_table_lock);
2089 new = pud_alloc_one(mm, address);
2090 spin_lock(&mm->page_table_lock);
2091 if (!new)
2092 return NULL;
2093
2094 /*
2095 * Because we dropped the lock, we should re-check the
2096 * entry, as somebody else could have populated it..
2097 */
2098 if (pgd_present(*pgd)) {
2099 pud_free(new);
2100 goto out;
2101 }
2102 pgd_populate(mm, pgd, new);
2103 out:
2104 return pud_offset(pgd, address);
2105}
2106#endif /* __PAGETABLE_PUD_FOLDED */
2107
2108#ifndef __PAGETABLE_PMD_FOLDED
2109/*
2110 * Allocate page middle directory.
2111 *
2112 * We've already handled the fast-path in-line, and we own the
2113 * page table lock.
2114 */
2115pmd_t fastcall *__pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2116{
2117 pmd_t *new;
2118
2119 spin_unlock(&mm->page_table_lock);
2120 new = pmd_alloc_one(mm, address);
2121 spin_lock(&mm->page_table_lock);
2122 if (!new)
2123 return NULL;
2124
2125 /*
2126 * Because we dropped the lock, we should re-check the
2127 * entry, as somebody else could have populated it..
2128 */
2129#ifndef __ARCH_HAS_4LEVEL_HACK
2130 if (pud_present(*pud)) {
2131 pmd_free(new);
2132 goto out;
2133 }
2134 pud_populate(mm, pud, new);
2135#else
2136 if (pgd_present(*pud)) {
2137 pmd_free(new);
2138 goto out;
2139 }
2140 pgd_populate(mm, pud, new);
2141#endif /* __ARCH_HAS_4LEVEL_HACK */
2142
2143 out:
2144 return pmd_offset(pud, address);
2145}
2146#endif /* __PAGETABLE_PMD_FOLDED */
2147
2148int make_pages_present(unsigned long addr, unsigned long end)
2149{
2150 int ret, len, write;
2151 struct vm_area_struct * vma;
2152
2153 vma = find_vma(current->mm, addr);
2154 if (!vma)
2155 return -1;
2156 write = (vma->vm_flags & VM_WRITE) != 0;
2157 if (addr >= end)
2158 BUG();
2159 if (end > vma->vm_end)
2160 BUG();
2161 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2162 ret = get_user_pages(current, current->mm, addr,
2163 len, write, 0, NULL, NULL);
2164 if (ret < 0)
2165 return ret;
2166 return ret == len ? 0 : -1;
2167}
2168
2169/*
2170 * Map a vmalloc()-space virtual address to the physical page.
2171 */
2172struct page * vmalloc_to_page(void * vmalloc_addr)
2173{
2174 unsigned long addr = (unsigned long) vmalloc_addr;
2175 struct page *page = NULL;
2176 pgd_t *pgd = pgd_offset_k(addr);
2177 pud_t *pud;
2178 pmd_t *pmd;
2179 pte_t *ptep, pte;
2180
2181 if (!pgd_none(*pgd)) {
2182 pud = pud_offset(pgd, addr);
2183 if (!pud_none(*pud)) {
2184 pmd = pmd_offset(pud, addr);
2185 if (!pmd_none(*pmd)) {
2186 ptep = pte_offset_map(pmd, addr);
2187 pte = *ptep;
2188 if (pte_present(pte))
2189 page = pte_page(pte);
2190 pte_unmap(ptep);
2191 }
2192 }
2193 }
2194 return page;
2195}
2196
2197EXPORT_SYMBOL(vmalloc_to_page);
2198
2199/*
2200 * Map a vmalloc()-space virtual address to the physical page frame number.
2201 */
2202unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2203{
2204 return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2205}
2206
2207EXPORT_SYMBOL(vmalloc_to_pfn);
2208
2209/*
2210 * update_mem_hiwater
2211 * - update per process rss and vm high water data
2212 */
2213void update_mem_hiwater(struct task_struct *tsk)
2214{
2215 if (tsk->mm) {
2216 unsigned long rss = get_mm_counter(tsk->mm, rss);
2217
2218 if (tsk->mm->hiwater_rss < rss)
2219 tsk->mm->hiwater_rss = rss;
2220 if (tsk->mm->hiwater_vm < tsk->mm->total_vm)
2221 tsk->mm->hiwater_vm = tsk->mm->total_vm;
2222 }
2223}
2224
2225#if !defined(__HAVE_ARCH_GATE_AREA)
2226
2227#if defined(AT_SYSINFO_EHDR)
2228struct vm_area_struct gate_vma;
2229
2230static int __init gate_vma_init(void)
2231{
2232 gate_vma.vm_mm = NULL;
2233 gate_vma.vm_start = FIXADDR_USER_START;
2234 gate_vma.vm_end = FIXADDR_USER_END;
2235 gate_vma.vm_page_prot = PAGE_READONLY;
2236 gate_vma.vm_flags = 0;
2237 return 0;
2238}
2239__initcall(gate_vma_init);
2240#endif
2241
2242struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2243{
2244#ifdef AT_SYSINFO_EHDR
2245 return &gate_vma;
2246#else
2247 return NULL;
2248#endif
2249}
2250
2251int in_gate_area_no_task(unsigned long addr)
2252{
2253#ifdef AT_SYSINFO_EHDR
2254 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2255 return 1;
2256#endif
2257 return 0;
2258}
2259
2260#endif /* __HAVE_ARCH_GATE_AREA */