projects/linux·blob v2.6.21 · refs

2738 lines · 72.9 KiB

1/*
2 * linux/mm/memory.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
10 */
11
12/*
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
15 *
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
18 * far as I could see.
19 *
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21 */
22
23/*
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
29 */
30
31/*
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh ([email protected])
34 *
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * ([email protected])
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/delayacct.h>
51#include <linux/init.h>
52#include <linux/writeback.h>
53
54#include <asm/pgalloc.h>
55#include <asm/uaccess.h>
56#include <asm/tlb.h>
57#include <asm/tlbflush.h>
58#include <asm/pgtable.h>
59
60#include <linux/swapops.h>
61#include <linux/elf.h>
62
63#ifndef CONFIG_NEED_MULTIPLE_NODES
64/* use the per-pgdat data instead for discontigmem - mbligh */
65unsigned long max_mapnr;
66struct page *mem_map;
67
68EXPORT_SYMBOL(max_mapnr);
69EXPORT_SYMBOL(mem_map);
70#endif
71
72unsigned long num_physpages;
73/*
74 * A number of key systems in x86 including ioremap() rely on the assumption
75 * that high_memory defines the upper bound on direct map memory, then end
76 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
77 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
78 * and ZONE_HIGHMEM.
79 */
80void * high_memory;
81unsigned long vmalloc_earlyreserve;
82
83EXPORT_SYMBOL(num_physpages);
84EXPORT_SYMBOL(high_memory);
85EXPORT_SYMBOL(vmalloc_earlyreserve);
86
87int randomize_va_space __read_mostly = 1;
88
89static int __init disable_randmaps(char *s)
90{
91 randomize_va_space = 0;
92 return 1;
93}
94__setup("norandmaps", disable_randmaps);
95
96
97/*
98 * If a p?d_bad entry is found while walking page tables, report
99 * the error, before resetting entry to p?d_none. Usually (but
100 * very seldom) called out from the p?d_none_or_clear_bad macros.
101 */
102
103void pgd_clear_bad(pgd_t *pgd)
104{
105 pgd_ERROR(*pgd);
106 pgd_clear(pgd);
107}
108
109void pud_clear_bad(pud_t *pud)
110{
111 pud_ERROR(*pud);
112 pud_clear(pud);
113}
114
115void pmd_clear_bad(pmd_t *pmd)
116{
117 pmd_ERROR(*pmd);
118 pmd_clear(pmd);
119}
120
121/*
122 * Note: this doesn't free the actual pages themselves. That
123 * has been handled earlier when unmapping all the memory regions.
124 */
125static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
126{
127 struct page *page = pmd_page(*pmd);
128 pmd_clear(pmd);
129 pte_lock_deinit(page);
130 pte_free_tlb(tlb, page);
131 dec_zone_page_state(page, NR_PAGETABLE);
132 tlb->mm->nr_ptes--;
133}
134
135static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
136 unsigned long addr, unsigned long end,
137 unsigned long floor, unsigned long ceiling)
138{
139 pmd_t *pmd;
140 unsigned long next;
141 unsigned long start;
142
143 start = addr;
144 pmd = pmd_offset(pud, addr);
145 do {
146 next = pmd_addr_end(addr, end);
147 if (pmd_none_or_clear_bad(pmd))
148 continue;
149 free_pte_range(tlb, pmd);
150 } while (pmd++, addr = next, addr != end);
151
152 start &= PUD_MASK;
153 if (start < floor)
154 return;
155 if (ceiling) {
156 ceiling &= PUD_MASK;
157 if (!ceiling)
158 return;
159 }
160 if (end - 1 > ceiling - 1)
161 return;
162
163 pmd = pmd_offset(pud, start);
164 pud_clear(pud);
165 pmd_free_tlb(tlb, pmd);
166}
167
168static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
169 unsigned long addr, unsigned long end,
170 unsigned long floor, unsigned long ceiling)
171{
172 pud_t *pud;
173 unsigned long next;
174 unsigned long start;
175
176 start = addr;
177 pud = pud_offset(pgd, addr);
178 do {
179 next = pud_addr_end(addr, end);
180 if (pud_none_or_clear_bad(pud))
181 continue;
182 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
183 } while (pud++, addr = next, addr != end);
184
185 start &= PGDIR_MASK;
186 if (start < floor)
187 return;
188 if (ceiling) {
189 ceiling &= PGDIR_MASK;
190 if (!ceiling)
191 return;
192 }
193 if (end - 1 > ceiling - 1)
194 return;
195
196 pud = pud_offset(pgd, start);
197 pgd_clear(pgd);
198 pud_free_tlb(tlb, pud);
199}
200
201/*
202 * This function frees user-level page tables of a process.
203 *
204 * Must be called with pagetable lock held.
205 */
206void free_pgd_range(struct mmu_gather **tlb,
207 unsigned long addr, unsigned long end,
208 unsigned long floor, unsigned long ceiling)
209{
210 pgd_t *pgd;
211 unsigned long next;
212 unsigned long start;
213
214 /*
215 * The next few lines have given us lots of grief...
216 *
217 * Why are we testing PMD* at this top level? Because often
218 * there will be no work to do at all, and we'd prefer not to
219 * go all the way down to the bottom just to discover that.
220 *
221 * Why all these "- 1"s? Because 0 represents both the bottom
222 * of the address space and the top of it (using -1 for the
223 * top wouldn't help much: the masks would do the wrong thing).
224 * The rule is that addr 0 and floor 0 refer to the bottom of
225 * the address space, but end 0 and ceiling 0 refer to the top
226 * Comparisons need to use "end - 1" and "ceiling - 1" (though
227 * that end 0 case should be mythical).
228 *
229 * Wherever addr is brought up or ceiling brought down, we must
230 * be careful to reject "the opposite 0" before it confuses the
231 * subsequent tests. But what about where end is brought down
232 * by PMD_SIZE below? no, end can't go down to 0 there.
233 *
234 * Whereas we round start (addr) and ceiling down, by different
235 * masks at different levels, in order to test whether a table
236 * now has no other vmas using it, so can be freed, we don't
237 * bother to round floor or end up - the tests don't need that.
238 */
239
240 addr &= PMD_MASK;
241 if (addr < floor) {
242 addr += PMD_SIZE;
243 if (!addr)
244 return;
245 }
246 if (ceiling) {
247 ceiling &= PMD_MASK;
248 if (!ceiling)
249 return;
250 }
251 if (end - 1 > ceiling - 1)
252 end -= PMD_SIZE;
253 if (addr > end - 1)
254 return;
255
256 start = addr;
257 pgd = pgd_offset((*tlb)->mm, addr);
258 do {
259 next = pgd_addr_end(addr, end);
260 if (pgd_none_or_clear_bad(pgd))
261 continue;
262 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
263 } while (pgd++, addr = next, addr != end);
264
265 if (!(*tlb)->fullmm)
266 flush_tlb_pgtables((*tlb)->mm, start, end);
267}
268
269void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
270 unsigned long floor, unsigned long ceiling)
271{
272 while (vma) {
273 struct vm_area_struct *next = vma->vm_next;
274 unsigned long addr = vma->vm_start;
275
276 /*
277 * Hide vma from rmap and vmtruncate before freeing pgtables
278 */
279 anon_vma_unlink(vma);
280 unlink_file_vma(vma);
281
282 if (is_vm_hugetlb_page(vma)) {
283 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
284 floor, next? next->vm_start: ceiling);
285 } else {
286 /*
287 * Optimization: gather nearby vmas into one call down
288 */
289 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
290 && !is_vm_hugetlb_page(next)) {
291 vma = next;
292 next = vma->vm_next;
293 anon_vma_unlink(vma);
294 unlink_file_vma(vma);
295 }
296 free_pgd_range(tlb, addr, vma->vm_end,
297 floor, next? next->vm_start: ceiling);
298 }
299 vma = next;
300 }
301}
302
303int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
304{
305 struct page *new = pte_alloc_one(mm, address);
306 if (!new)
307 return -ENOMEM;
308
309 pte_lock_init(new);
310 spin_lock(&mm->page_table_lock);
311 if (pmd_present(*pmd)) { /* Another has populated it */
312 pte_lock_deinit(new);
313 pte_free(new);
314 } else {
315 mm->nr_ptes++;
316 inc_zone_page_state(new, NR_PAGETABLE);
317 pmd_populate(mm, pmd, new);
318 }
319 spin_unlock(&mm->page_table_lock);
320 return 0;
321}
322
323int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
324{
325 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
326 if (!new)
327 return -ENOMEM;
328
329 spin_lock(&init_mm.page_table_lock);
330 if (pmd_present(*pmd)) /* Another has populated it */
331 pte_free_kernel(new);
332 else
333 pmd_populate_kernel(&init_mm, pmd, new);
334 spin_unlock(&init_mm.page_table_lock);
335 return 0;
336}
337
338static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
339{
340 if (file_rss)
341 add_mm_counter(mm, file_rss, file_rss);
342 if (anon_rss)
343 add_mm_counter(mm, anon_rss, anon_rss);
344}
345
346/*
347 * This function is called to print an error when a bad pte
348 * is found. For example, we might have a PFN-mapped pte in
349 * a region that doesn't allow it.
350 *
351 * The calling function must still handle the error.
352 */
353void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
354{
355 printk(KERN_ERR "Bad pte = %08llx, process = %s, "
356 "vm_flags = %lx, vaddr = %lx\n",
357 (long long)pte_val(pte),
358 (vma->vm_mm == current->mm ? current->comm : "???"),
359 vma->vm_flags, vaddr);
360 dump_stack();
361}
362
363static inline int is_cow_mapping(unsigned int flags)
364{
365 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
366}
367
368/*
369 * This function gets the "struct page" associated with a pte.
370 *
371 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
372 * will have each page table entry just pointing to a raw page frame
373 * number, and as far as the VM layer is concerned, those do not have
374 * pages associated with them - even if the PFN might point to memory
375 * that otherwise is perfectly fine and has a "struct page".
376 *
377 * The way we recognize those mappings is through the rules set up
378 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
379 * and the vm_pgoff will point to the first PFN mapped: thus every
380 * page that is a raw mapping will always honor the rule
381 *
382 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
383 *
384 * and if that isn't true, the page has been COW'ed (in which case it
385 * _does_ have a "struct page" associated with it even if it is in a
386 * VM_PFNMAP range).
387 */
388struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
389{
390 unsigned long pfn = pte_pfn(pte);
391
392 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
393 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
394 if (pfn == vma->vm_pgoff + off)
395 return NULL;
396 if (!is_cow_mapping(vma->vm_flags))
397 return NULL;
398 }
399
400 /*
401 * Add some anal sanity checks for now. Eventually,
402 * we should just do "return pfn_to_page(pfn)", but
403 * in the meantime we check that we get a valid pfn,
404 * and that the resulting page looks ok.
405 */
406 if (unlikely(!pfn_valid(pfn))) {
407 print_bad_pte(vma, pte, addr);
408 return NULL;
409 }
410
411 /*
412 * NOTE! We still have PageReserved() pages in the page
413 * tables.
414 *
415 * The PAGE_ZERO() pages and various VDSO mappings can
416 * cause them to exist.
417 */
418 return pfn_to_page(pfn);
419}
420
421/*
422 * copy one vm_area from one task to the other. Assumes the page tables
423 * already present in the new task to be cleared in the whole range
424 * covered by this vma.
425 */
426
427static inline void
428copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
429 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
430 unsigned long addr, int *rss)
431{
432 unsigned long vm_flags = vma->vm_flags;
433 pte_t pte = *src_pte;
434 struct page *page;
435
436 /* pte contains position in swap or file, so copy. */
437 if (unlikely(!pte_present(pte))) {
438 if (!pte_file(pte)) {
439 swp_entry_t entry = pte_to_swp_entry(pte);
440
441 swap_duplicate(entry);
442 /* make sure dst_mm is on swapoff's mmlist. */
443 if (unlikely(list_empty(&dst_mm->mmlist))) {
444 spin_lock(&mmlist_lock);
445 if (list_empty(&dst_mm->mmlist))
446 list_add(&dst_mm->mmlist,
447 &src_mm->mmlist);
448 spin_unlock(&mmlist_lock);
449 }
450 if (is_write_migration_entry(entry) &&
451 is_cow_mapping(vm_flags)) {
452 /*
453 * COW mappings require pages in both parent
454 * and child to be set to read.
455 */
456 make_migration_entry_read(&entry);
457 pte = swp_entry_to_pte(entry);
458 set_pte_at(src_mm, addr, src_pte, pte);
459 }
460 }
461 goto out_set_pte;
462 }
463
464 /*
465 * If it's a COW mapping, write protect it both
466 * in the parent and the child
467 */
468 if (is_cow_mapping(vm_flags)) {
469 ptep_set_wrprotect(src_mm, addr, src_pte);
470 pte = pte_wrprotect(pte);
471 }
472
473 /*
474 * If it's a shared mapping, mark it clean in
475 * the child
476 */
477 if (vm_flags & VM_SHARED)
478 pte = pte_mkclean(pte);
479 pte = pte_mkold(pte);
480
481 page = vm_normal_page(vma, addr, pte);
482 if (page) {
483 get_page(page);
484 page_dup_rmap(page);
485 rss[!!PageAnon(page)]++;
486 }
487
488out_set_pte:
489 set_pte_at(dst_mm, addr, dst_pte, pte);
490}
491
492static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
493 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
494 unsigned long addr, unsigned long end)
495{
496 pte_t *src_pte, *dst_pte;
497 spinlock_t *src_ptl, *dst_ptl;
498 int progress = 0;
499 int rss[2];
500
501again:
502 rss[1] = rss[0] = 0;
503 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
504 if (!dst_pte)
505 return -ENOMEM;
506 src_pte = pte_offset_map_nested(src_pmd, addr);
507 src_ptl = pte_lockptr(src_mm, src_pmd);
508 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
509 arch_enter_lazy_mmu_mode();
510
511 do {
512 /*
513 * We are holding two locks at this point - either of them
514 * could generate latencies in another task on another CPU.
515 */
516 if (progress >= 32) {
517 progress = 0;
518 if (need_resched() ||
519 need_lockbreak(src_ptl) ||
520 need_lockbreak(dst_ptl))
521 break;
522 }
523 if (pte_none(*src_pte)) {
524 progress++;
525 continue;
526 }
527 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
528 progress += 8;
529 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
530
531 arch_leave_lazy_mmu_mode();
532 spin_unlock(src_ptl);
533 pte_unmap_nested(src_pte - 1);
534 add_mm_rss(dst_mm, rss[0], rss[1]);
535 pte_unmap_unlock(dst_pte - 1, dst_ptl);
536 cond_resched();
537 if (addr != end)
538 goto again;
539 return 0;
540}
541
542static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
543 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
544 unsigned long addr, unsigned long end)
545{
546 pmd_t *src_pmd, *dst_pmd;
547 unsigned long next;
548
549 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
550 if (!dst_pmd)
551 return -ENOMEM;
552 src_pmd = pmd_offset(src_pud, addr);
553 do {
554 next = pmd_addr_end(addr, end);
555 if (pmd_none_or_clear_bad(src_pmd))
556 continue;
557 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
558 vma, addr, next))
559 return -ENOMEM;
560 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
561 return 0;
562}
563
564static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
565 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
566 unsigned long addr, unsigned long end)
567{
568 pud_t *src_pud, *dst_pud;
569 unsigned long next;
570
571 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
572 if (!dst_pud)
573 return -ENOMEM;
574 src_pud = pud_offset(src_pgd, addr);
575 do {
576 next = pud_addr_end(addr, end);
577 if (pud_none_or_clear_bad(src_pud))
578 continue;
579 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
580 vma, addr, next))
581 return -ENOMEM;
582 } while (dst_pud++, src_pud++, addr = next, addr != end);
583 return 0;
584}
585
586int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
587 struct vm_area_struct *vma)
588{
589 pgd_t *src_pgd, *dst_pgd;
590 unsigned long next;
591 unsigned long addr = vma->vm_start;
592 unsigned long end = vma->vm_end;
593
594 /*
595 * Don't copy ptes where a page fault will fill them correctly.
596 * Fork becomes much lighter when there are big shared or private
597 * readonly mappings. The tradeoff is that copy_page_range is more
598 * efficient than faulting.
599 */
600 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
601 if (!vma->anon_vma)
602 return 0;
603 }
604
605 if (is_vm_hugetlb_page(vma))
606 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
607
608 dst_pgd = pgd_offset(dst_mm, addr);
609 src_pgd = pgd_offset(src_mm, addr);
610 do {
611 next = pgd_addr_end(addr, end);
612 if (pgd_none_or_clear_bad(src_pgd))
613 continue;
614 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
615 vma, addr, next))
616 return -ENOMEM;
617 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
618 return 0;
619}
620
621static unsigned long zap_pte_range(struct mmu_gather *tlb,
622 struct vm_area_struct *vma, pmd_t *pmd,
623 unsigned long addr, unsigned long end,
624 long *zap_work, struct zap_details *details)
625{
626 struct mm_struct *mm = tlb->mm;
627 pte_t *pte;
628 spinlock_t *ptl;
629 int file_rss = 0;
630 int anon_rss = 0;
631
632 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
633 arch_enter_lazy_mmu_mode();
634 do {
635 pte_t ptent = *pte;
636 if (pte_none(ptent)) {
637 (*zap_work)--;
638 continue;
639 }
640
641 (*zap_work) -= PAGE_SIZE;
642
643 if (pte_present(ptent)) {
644 struct page *page;
645
646 page = vm_normal_page(vma, addr, ptent);
647 if (unlikely(details) && page) {
648 /*
649 * unmap_shared_mapping_pages() wants to
650 * invalidate cache without truncating:
651 * unmap shared but keep private pages.
652 */
653 if (details->check_mapping &&
654 details->check_mapping != page->mapping)
655 continue;
656 /*
657 * Each page->index must be checked when
658 * invalidating or truncating nonlinear.
659 */
660 if (details->nonlinear_vma &&
661 (page->index < details->first_index ||
662 page->index > details->last_index))
663 continue;
664 }
665 ptent = ptep_get_and_clear_full(mm, addr, pte,
666 tlb->fullmm);
667 tlb_remove_tlb_entry(tlb, pte, addr);
668 if (unlikely(!page))
669 continue;
670 if (unlikely(details) && details->nonlinear_vma
671 && linear_page_index(details->nonlinear_vma,
672 addr) != page->index)
673 set_pte_at(mm, addr, pte,
674 pgoff_to_pte(page->index));
675 if (PageAnon(page))
676 anon_rss--;
677 else {
678 if (pte_dirty(ptent))
679 set_page_dirty(page);
680 if (pte_young(ptent))
681 SetPageReferenced(page);
682 file_rss--;
683 }
684 page_remove_rmap(page, vma);
685 tlb_remove_page(tlb, page);
686 continue;
687 }
688 /*
689 * If details->check_mapping, we leave swap entries;
690 * if details->nonlinear_vma, we leave file entries.
691 */
692 if (unlikely(details))
693 continue;
694 if (!pte_file(ptent))
695 free_swap_and_cache(pte_to_swp_entry(ptent));
696 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
697 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
698
699 add_mm_rss(mm, file_rss, anon_rss);
700 arch_leave_lazy_mmu_mode();
701 pte_unmap_unlock(pte - 1, ptl);
702
703 return addr;
704}
705
706static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
707 struct vm_area_struct *vma, pud_t *pud,
708 unsigned long addr, unsigned long end,
709 long *zap_work, struct zap_details *details)
710{
711 pmd_t *pmd;
712 unsigned long next;
713
714 pmd = pmd_offset(pud, addr);
715 do {
716 next = pmd_addr_end(addr, end);
717 if (pmd_none_or_clear_bad(pmd)) {
718 (*zap_work)--;
719 continue;
720 }
721 next = zap_pte_range(tlb, vma, pmd, addr, next,
722 zap_work, details);
723 } while (pmd++, addr = next, (addr != end && *zap_work > 0));
724
725 return addr;
726}
727
728static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
729 struct vm_area_struct *vma, pgd_t *pgd,
730 unsigned long addr, unsigned long end,
731 long *zap_work, struct zap_details *details)
732{
733 pud_t *pud;
734 unsigned long next;
735
736 pud = pud_offset(pgd, addr);
737 do {
738 next = pud_addr_end(addr, end);
739 if (pud_none_or_clear_bad(pud)) {
740 (*zap_work)--;
741 continue;
742 }
743 next = zap_pmd_range(tlb, vma, pud, addr, next,
744 zap_work, details);
745 } while (pud++, addr = next, (addr != end && *zap_work > 0));
746
747 return addr;
748}
749
750static unsigned long unmap_page_range(struct mmu_gather *tlb,
751 struct vm_area_struct *vma,
752 unsigned long addr, unsigned long end,
753 long *zap_work, struct zap_details *details)
754{
755 pgd_t *pgd;
756 unsigned long next;
757
758 if (details && !details->check_mapping && !details->nonlinear_vma)
759 details = NULL;
760
761 BUG_ON(addr >= end);
762 tlb_start_vma(tlb, vma);
763 pgd = pgd_offset(vma->vm_mm, addr);
764 do {
765 next = pgd_addr_end(addr, end);
766 if (pgd_none_or_clear_bad(pgd)) {
767 (*zap_work)--;
768 continue;
769 }
770 next = zap_pud_range(tlb, vma, pgd, addr, next,
771 zap_work, details);
772 } while (pgd++, addr = next, (addr != end && *zap_work > 0));
773 tlb_end_vma(tlb, vma);
774
775 return addr;
776}
777
778#ifdef CONFIG_PREEMPT
779# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
780#else
781/* No preempt: go for improved straight-line efficiency */
782# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
783#endif
784
785/**
786 * unmap_vmas - unmap a range of memory covered by a list of vma's
787 * @tlbp: address of the caller's struct mmu_gather
788 * @vma: the starting vma
789 * @start_addr: virtual address at which to start unmapping
790 * @end_addr: virtual address at which to end unmapping
791 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
792 * @details: details of nonlinear truncation or shared cache invalidation
793 *
794 * Returns the end address of the unmapping (restart addr if interrupted).
795 *
796 * Unmap all pages in the vma list.
797 *
798 * We aim to not hold locks for too long (for scheduling latency reasons).
799 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
800 * return the ending mmu_gather to the caller.
801 *
802 * Only addresses between `start' and `end' will be unmapped.
803 *
804 * The VMA list must be sorted in ascending virtual address order.
805 *
806 * unmap_vmas() assumes that the caller will flush the whole unmapped address
807 * range after unmap_vmas() returns. So the only responsibility here is to
808 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
809 * drops the lock and schedules.
810 */
811unsigned long unmap_vmas(struct mmu_gather **tlbp,
812 struct vm_area_struct *vma, unsigned long start_addr,
813 unsigned long end_addr, unsigned long *nr_accounted,
814 struct zap_details *details)
815{
816 long zap_work = ZAP_BLOCK_SIZE;
817 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
818 int tlb_start_valid = 0;
819 unsigned long start = start_addr;
820 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
821 int fullmm = (*tlbp)->fullmm;
822
823 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
824 unsigned long end;
825
826 start = max(vma->vm_start, start_addr);
827 if (start >= vma->vm_end)
828 continue;
829 end = min(vma->vm_end, end_addr);
830 if (end <= vma->vm_start)
831 continue;
832
833 if (vma->vm_flags & VM_ACCOUNT)
834 *nr_accounted += (end - start) >> PAGE_SHIFT;
835
836 while (start != end) {
837 if (!tlb_start_valid) {
838 tlb_start = start;
839 tlb_start_valid = 1;
840 }
841
842 if (unlikely(is_vm_hugetlb_page(vma))) {
843 unmap_hugepage_range(vma, start, end);
844 zap_work -= (end - start) /
845 (HPAGE_SIZE / PAGE_SIZE);
846 start = end;
847 } else
848 start = unmap_page_range(*tlbp, vma,
849 start, end, &zap_work, details);
850
851 if (zap_work > 0) {
852 BUG_ON(start != end);
853 break;
854 }
855
856 tlb_finish_mmu(*tlbp, tlb_start, start);
857
858 if (need_resched() ||
859 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
860 if (i_mmap_lock) {
861 *tlbp = NULL;
862 goto out;
863 }
864 cond_resched();
865 }
866
867 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
868 tlb_start_valid = 0;
869 zap_work = ZAP_BLOCK_SIZE;
870 }
871 }
872out:
873 return start; /* which is now the end (or restart) address */
874}
875
876/**
877 * zap_page_range - remove user pages in a given range
878 * @vma: vm_area_struct holding the applicable pages
879 * @address: starting address of pages to zap
880 * @size: number of bytes to zap
881 * @details: details of nonlinear truncation or shared cache invalidation
882 */
883unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
884 unsigned long size, struct zap_details *details)
885{
886 struct mm_struct *mm = vma->vm_mm;
887 struct mmu_gather *tlb;
888 unsigned long end = address + size;
889 unsigned long nr_accounted = 0;
890
891 lru_add_drain();
892 tlb = tlb_gather_mmu(mm, 0);
893 update_hiwater_rss(mm);
894 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
895 if (tlb)
896 tlb_finish_mmu(tlb, address, end);
897 return end;
898}
899
900/*
901 * Do a quick page-table lookup for a single page.
902 */
903struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
904 unsigned int flags)
905{
906 pgd_t *pgd;
907 pud_t *pud;
908 pmd_t *pmd;
909 pte_t *ptep, pte;
910 spinlock_t *ptl;
911 struct page *page;
912 struct mm_struct *mm = vma->vm_mm;
913
914 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
915 if (!IS_ERR(page)) {
916 BUG_ON(flags & FOLL_GET);
917 goto out;
918 }
919
920 page = NULL;
921 pgd = pgd_offset(mm, address);
922 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
923 goto no_page_table;
924
925 pud = pud_offset(pgd, address);
926 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
927 goto no_page_table;
928
929 pmd = pmd_offset(pud, address);
930 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
931 goto no_page_table;
932
933 if (pmd_huge(*pmd)) {
934 BUG_ON(flags & FOLL_GET);
935 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
936 goto out;
937 }
938
939 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
940 if (!ptep)
941 goto out;
942
943 pte = *ptep;
944 if (!pte_present(pte))
945 goto unlock;
946 if ((flags & FOLL_WRITE) && !pte_write(pte))
947 goto unlock;
948 page = vm_normal_page(vma, address, pte);
949 if (unlikely(!page))
950 goto unlock;
951
952 if (flags & FOLL_GET)
953 get_page(page);
954 if (flags & FOLL_TOUCH) {
955 if ((flags & FOLL_WRITE) &&
956 !pte_dirty(pte) && !PageDirty(page))
957 set_page_dirty(page);
958 mark_page_accessed(page);
959 }
960unlock:
961 pte_unmap_unlock(ptep, ptl);
962out:
963 return page;
964
965no_page_table:
966 /*
967 * When core dumping an enormous anonymous area that nobody
968 * has touched so far, we don't want to allocate page tables.
969 */
970 if (flags & FOLL_ANON) {
971 page = ZERO_PAGE(address);
972 if (flags & FOLL_GET)
973 get_page(page);
974 BUG_ON(flags & FOLL_WRITE);
975 }
976 return page;
977}
978
979int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
980 unsigned long start, int len, int write, int force,
981 struct page **pages, struct vm_area_struct **vmas)
982{
983 int i;
984 unsigned int vm_flags;
985
986 /*
987 * Require read or write permissions.
988 * If 'force' is set, we only require the "MAY" flags.
989 */
990 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
991 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
992 i = 0;
993
994 do {
995 struct vm_area_struct *vma;
996 unsigned int foll_flags;
997
998 vma = find_extend_vma(mm, start);
999 if (!vma && in_gate_area(tsk, start)) {
1000 unsigned long pg = start & PAGE_MASK;
1001 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1002 pgd_t *pgd;
1003 pud_t *pud;
1004 pmd_t *pmd;
1005 pte_t *pte;
1006 if (write) /* user gate pages are read-only */
1007 return i ? : -EFAULT;
1008 if (pg > TASK_SIZE)
1009 pgd = pgd_offset_k(pg);
1010 else
1011 pgd = pgd_offset_gate(mm, pg);
1012 BUG_ON(pgd_none(*pgd));
1013 pud = pud_offset(pgd, pg);
1014 BUG_ON(pud_none(*pud));
1015 pmd = pmd_offset(pud, pg);
1016 if (pmd_none(*pmd))
1017 return i ? : -EFAULT;
1018 pte = pte_offset_map(pmd, pg);
1019 if (pte_none(*pte)) {
1020 pte_unmap(pte);
1021 return i ? : -EFAULT;
1022 }
1023 if (pages) {
1024 struct page *page = vm_normal_page(gate_vma, start, *pte);
1025 pages[i] = page;
1026 if (page)
1027 get_page(page);
1028 }
1029 pte_unmap(pte);
1030 if (vmas)
1031 vmas[i] = gate_vma;
1032 i++;
1033 start += PAGE_SIZE;
1034 len--;
1035 continue;
1036 }
1037
1038 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1039 || !(vm_flags & vma->vm_flags))
1040 return i ? : -EFAULT;
1041
1042 if (is_vm_hugetlb_page(vma)) {
1043 i = follow_hugetlb_page(mm, vma, pages, vmas,
1044 &start, &len, i);
1045 continue;
1046 }
1047
1048 foll_flags = FOLL_TOUCH;
1049 if (pages)
1050 foll_flags |= FOLL_GET;
1051 if (!write && !(vma->vm_flags & VM_LOCKED) &&
1052 (!vma->vm_ops || !vma->vm_ops->nopage))
1053 foll_flags |= FOLL_ANON;
1054
1055 do {
1056 struct page *page;
1057
1058 if (write)
1059 foll_flags |= FOLL_WRITE;
1060
1061 cond_resched();
1062 while (!(page = follow_page(vma, start, foll_flags))) {
1063 int ret;
1064 ret = __handle_mm_fault(mm, vma, start,
1065 foll_flags & FOLL_WRITE);
1066 /*
1067 * The VM_FAULT_WRITE bit tells us that do_wp_page has
1068 * broken COW when necessary, even if maybe_mkwrite
1069 * decided not to set pte_write. We can thus safely do
1070 * subsequent page lookups as if they were reads.
1071 */
1072 if (ret & VM_FAULT_WRITE)
1073 foll_flags &= ~FOLL_WRITE;
1074
1075 switch (ret & ~VM_FAULT_WRITE) {
1076 case VM_FAULT_MINOR:
1077 tsk->min_flt++;
1078 break;
1079 case VM_FAULT_MAJOR:
1080 tsk->maj_flt++;
1081 break;
1082 case VM_FAULT_SIGBUS:
1083 return i ? i : -EFAULT;
1084 case VM_FAULT_OOM:
1085 return i ? i : -ENOMEM;
1086 default:
1087 BUG();
1088 }
1089 cond_resched();
1090 }
1091 if (pages) {
1092 pages[i] = page;
1093
1094 flush_anon_page(vma, page, start);
1095 flush_dcache_page(page);
1096 }
1097 if (vmas)
1098 vmas[i] = vma;
1099 i++;
1100 start += PAGE_SIZE;
1101 len--;
1102 } while (len && start < vma->vm_end);
1103 } while (len);
1104 return i;
1105}
1106EXPORT_SYMBOL(get_user_pages);
1107
1108static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1109 unsigned long addr, unsigned long end, pgprot_t prot)
1110{
1111 pte_t *pte;
1112 spinlock_t *ptl;
1113 int err = 0;
1114
1115 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1116 if (!pte)
1117 return -EAGAIN;
1118 arch_enter_lazy_mmu_mode();
1119 do {
1120 struct page *page = ZERO_PAGE(addr);
1121 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1122
1123 if (unlikely(!pte_none(*pte))) {
1124 err = -EEXIST;
1125 pte++;
1126 break;
1127 }
1128 page_cache_get(page);
1129 page_add_file_rmap(page);
1130 inc_mm_counter(mm, file_rss);
1131 set_pte_at(mm, addr, pte, zero_pte);
1132 } while (pte++, addr += PAGE_SIZE, addr != end);
1133 arch_leave_lazy_mmu_mode();
1134 pte_unmap_unlock(pte - 1, ptl);
1135 return err;
1136}
1137
1138static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1139 unsigned long addr, unsigned long end, pgprot_t prot)
1140{
1141 pmd_t *pmd;
1142 unsigned long next;
1143 int err;
1144
1145 pmd = pmd_alloc(mm, pud, addr);
1146 if (!pmd)
1147 return -EAGAIN;
1148 do {
1149 next = pmd_addr_end(addr, end);
1150 err = zeromap_pte_range(mm, pmd, addr, next, prot);
1151 if (err)
1152 break;
1153 } while (pmd++, addr = next, addr != end);
1154 return err;
1155}
1156
1157static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1158 unsigned long addr, unsigned long end, pgprot_t prot)
1159{
1160 pud_t *pud;
1161 unsigned long next;
1162 int err;
1163
1164 pud = pud_alloc(mm, pgd, addr);
1165 if (!pud)
1166 return -EAGAIN;
1167 do {
1168 next = pud_addr_end(addr, end);
1169 err = zeromap_pmd_range(mm, pud, addr, next, prot);
1170 if (err)
1171 break;
1172 } while (pud++, addr = next, addr != end);
1173 return err;
1174}
1175
1176int zeromap_page_range(struct vm_area_struct *vma,
1177 unsigned long addr, unsigned long size, pgprot_t prot)
1178{
1179 pgd_t *pgd;
1180 unsigned long next;
1181 unsigned long end = addr + size;
1182 struct mm_struct *mm = vma->vm_mm;
1183 int err;
1184
1185 BUG_ON(addr >= end);
1186 pgd = pgd_offset(mm, addr);
1187 flush_cache_range(vma, addr, end);
1188 do {
1189 next = pgd_addr_end(addr, end);
1190 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1191 if (err)
1192 break;
1193 } while (pgd++, addr = next, addr != end);
1194 return err;
1195}
1196
1197pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1198{
1199 pgd_t * pgd = pgd_offset(mm, addr);
1200 pud_t * pud = pud_alloc(mm, pgd, addr);
1201 if (pud) {
1202 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1203 if (pmd)
1204 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1205 }
1206 return NULL;
1207}
1208
1209/*
1210 * This is the old fallback for page remapping.
1211 *
1212 * For historical reasons, it only allows reserved pages. Only
1213 * old drivers should use this, and they needed to mark their
1214 * pages reserved for the old functions anyway.
1215 */
1216static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1217{
1218 int retval;
1219 pte_t *pte;
1220 spinlock_t *ptl;
1221
1222 retval = -EINVAL;
1223 if (PageAnon(page))
1224 goto out;
1225 retval = -ENOMEM;
1226 flush_dcache_page(page);
1227 pte = get_locked_pte(mm, addr, &ptl);
1228 if (!pte)
1229 goto out;
1230 retval = -EBUSY;
1231 if (!pte_none(*pte))
1232 goto out_unlock;
1233
1234 /* Ok, finally just insert the thing.. */
1235 get_page(page);
1236 inc_mm_counter(mm, file_rss);
1237 page_add_file_rmap(page);
1238 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1239
1240 retval = 0;
1241out_unlock:
1242 pte_unmap_unlock(pte, ptl);
1243out:
1244 return retval;
1245}
1246
1247/**
1248 * vm_insert_page - insert single page into user vma
1249 * @vma: user vma to map to
1250 * @addr: target user address of this page
1251 * @page: source kernel page
1252 *
1253 * This allows drivers to insert individual pages they've allocated
1254 * into a user vma.
1255 *
1256 * The page has to be a nice clean _individual_ kernel allocation.
1257 * If you allocate a compound page, you need to have marked it as
1258 * such (__GFP_COMP), or manually just split the page up yourself
1259 * (see split_page()).
1260 *
1261 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1262 * took an arbitrary page protection parameter. This doesn't allow
1263 * that. Your vma protection will have to be set up correctly, which
1264 * means that if you want a shared writable mapping, you'd better
1265 * ask for a shared writable mapping!
1266 *
1267 * The page does not need to be reserved.
1268 */
1269int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1270{
1271 if (addr < vma->vm_start || addr >= vma->vm_end)
1272 return -EFAULT;
1273 if (!page_count(page))
1274 return -EINVAL;
1275 vma->vm_flags |= VM_INSERTPAGE;
1276 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1277}
1278EXPORT_SYMBOL(vm_insert_page);
1279
1280/**
1281 * vm_insert_pfn - insert single pfn into user vma
1282 * @vma: user vma to map to
1283 * @addr: target user address of this page
1284 * @pfn: source kernel pfn
1285 *
1286 * Similar to vm_inert_page, this allows drivers to insert individual pages
1287 * they've allocated into a user vma. Same comments apply.
1288 *
1289 * This function should only be called from a vm_ops->fault handler, and
1290 * in that case the handler should return NULL.
1291 */
1292int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1293 unsigned long pfn)
1294{
1295 struct mm_struct *mm = vma->vm_mm;
1296 int retval;
1297 pte_t *pte, entry;
1298 spinlock_t *ptl;
1299
1300 BUG_ON(!(vma->vm_flags & VM_PFNMAP));
1301 BUG_ON(is_cow_mapping(vma->vm_flags));
1302
1303 retval = -ENOMEM;
1304 pte = get_locked_pte(mm, addr, &ptl);
1305 if (!pte)
1306 goto out;
1307 retval = -EBUSY;
1308 if (!pte_none(*pte))
1309 goto out_unlock;
1310
1311 /* Ok, finally just insert the thing.. */
1312 entry = pfn_pte(pfn, vma->vm_page_prot);
1313 set_pte_at(mm, addr, pte, entry);
1314 update_mmu_cache(vma, addr, entry);
1315
1316 retval = 0;
1317out_unlock:
1318 pte_unmap_unlock(pte, ptl);
1319
1320out:
1321 return retval;
1322}
1323EXPORT_SYMBOL(vm_insert_pfn);
1324
1325/*
1326 * maps a range of physical memory into the requested pages. the old
1327 * mappings are removed. any references to nonexistent pages results
1328 * in null mappings (currently treated as "copy-on-access")
1329 */
1330static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1331 unsigned long addr, unsigned long end,
1332 unsigned long pfn, pgprot_t prot)
1333{
1334 pte_t *pte;
1335 spinlock_t *ptl;
1336
1337 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1338 if (!pte)
1339 return -ENOMEM;
1340 arch_enter_lazy_mmu_mode();
1341 do {
1342 BUG_ON(!pte_none(*pte));
1343 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1344 pfn++;
1345 } while (pte++, addr += PAGE_SIZE, addr != end);
1346 arch_leave_lazy_mmu_mode();
1347 pte_unmap_unlock(pte - 1, ptl);
1348 return 0;
1349}
1350
1351static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1352 unsigned long addr, unsigned long end,
1353 unsigned long pfn, pgprot_t prot)
1354{
1355 pmd_t *pmd;
1356 unsigned long next;
1357
1358 pfn -= addr >> PAGE_SHIFT;
1359 pmd = pmd_alloc(mm, pud, addr);
1360 if (!pmd)
1361 return -ENOMEM;
1362 do {
1363 next = pmd_addr_end(addr, end);
1364 if (remap_pte_range(mm, pmd, addr, next,
1365 pfn + (addr >> PAGE_SHIFT), prot))
1366 return -ENOMEM;
1367 } while (pmd++, addr = next, addr != end);
1368 return 0;
1369}
1370
1371static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1372 unsigned long addr, unsigned long end,
1373 unsigned long pfn, pgprot_t prot)
1374{
1375 pud_t *pud;
1376 unsigned long next;
1377
1378 pfn -= addr >> PAGE_SHIFT;
1379 pud = pud_alloc(mm, pgd, addr);
1380 if (!pud)
1381 return -ENOMEM;
1382 do {
1383 next = pud_addr_end(addr, end);
1384 if (remap_pmd_range(mm, pud, addr, next,
1385 pfn + (addr >> PAGE_SHIFT), prot))
1386 return -ENOMEM;
1387 } while (pud++, addr = next, addr != end);
1388 return 0;
1389}
1390
1391/**
1392 * remap_pfn_range - remap kernel memory to userspace
1393 * @vma: user vma to map to
1394 * @addr: target user address to start at
1395 * @pfn: physical address of kernel memory
1396 * @size: size of map area
1397 * @prot: page protection flags for this mapping
1398 *
1399 * Note: this is only safe if the mm semaphore is held when called.
1400 */
1401int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1402 unsigned long pfn, unsigned long size, pgprot_t prot)
1403{
1404 pgd_t *pgd;
1405 unsigned long next;
1406 unsigned long end = addr + PAGE_ALIGN(size);
1407 struct mm_struct *mm = vma->vm_mm;
1408 int err;
1409
1410 /*
1411 * Physically remapped pages are special. Tell the
1412 * rest of the world about it:
1413 * VM_IO tells people not to look at these pages
1414 * (accesses can have side effects).
1415 * VM_RESERVED is specified all over the place, because
1416 * in 2.4 it kept swapout's vma scan off this vma; but
1417 * in 2.6 the LRU scan won't even find its pages, so this
1418 * flag means no more than count its pages in reserved_vm,
1419 * and omit it from core dump, even when VM_IO turned off.
1420 * VM_PFNMAP tells the core MM that the base pages are just
1421 * raw PFN mappings, and do not have a "struct page" associated
1422 * with them.
1423 *
1424 * There's a horrible special case to handle copy-on-write
1425 * behaviour that some programs depend on. We mark the "original"
1426 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1427 */
1428 if (is_cow_mapping(vma->vm_flags)) {
1429 if (addr != vma->vm_start || end != vma->vm_end)
1430 return -EINVAL;
1431 vma->vm_pgoff = pfn;
1432 }
1433
1434 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1435
1436 BUG_ON(addr >= end);
1437 pfn -= addr >> PAGE_SHIFT;
1438 pgd = pgd_offset(mm, addr);
1439 flush_cache_range(vma, addr, end);
1440 do {
1441 next = pgd_addr_end(addr, end);
1442 err = remap_pud_range(mm, pgd, addr, next,
1443 pfn + (addr >> PAGE_SHIFT), prot);
1444 if (err)
1445 break;
1446 } while (pgd++, addr = next, addr != end);
1447 return err;
1448}
1449EXPORT_SYMBOL(remap_pfn_range);
1450
1451/*
1452 * handle_pte_fault chooses page fault handler according to an entry
1453 * which was read non-atomically. Before making any commitment, on
1454 * those architectures or configurations (e.g. i386 with PAE) which
1455 * might give a mix of unmatched parts, do_swap_page and do_file_page
1456 * must check under lock before unmapping the pte and proceeding
1457 * (but do_wp_page is only called after already making such a check;
1458 * and do_anonymous_page and do_no_page can safely check later on).
1459 */
1460static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1461 pte_t *page_table, pte_t orig_pte)
1462{
1463 int same = 1;
1464#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1465 if (sizeof(pte_t) > sizeof(unsigned long)) {
1466 spinlock_t *ptl = pte_lockptr(mm, pmd);
1467 spin_lock(ptl);
1468 same = pte_same(*page_table, orig_pte);
1469 spin_unlock(ptl);
1470 }
1471#endif
1472 pte_unmap(page_table);
1473 return same;
1474}
1475
1476/*
1477 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
1478 * servicing faults for write access. In the normal case, do always want
1479 * pte_mkwrite. But get_user_pages can cause write faults for mappings
1480 * that do not have writing enabled, when used by access_process_vm.
1481 */
1482static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1483{
1484 if (likely(vma->vm_flags & VM_WRITE))
1485 pte = pte_mkwrite(pte);
1486 return pte;
1487}
1488
1489static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1490{
1491 /*
1492 * If the source page was a PFN mapping, we don't have
1493 * a "struct page" for it. We do a best-effort copy by
1494 * just copying from the original user address. If that
1495 * fails, we just zero-fill it. Live with it.
1496 */
1497 if (unlikely(!src)) {
1498 void *kaddr = kmap_atomic(dst, KM_USER0);
1499 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1500
1501 /*
1502 * This really shouldn't fail, because the page is there
1503 * in the page tables. But it might just be unreadable,
1504 * in which case we just give up and fill the result with
1505 * zeroes.
1506 */
1507 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1508 memset(kaddr, 0, PAGE_SIZE);
1509 kunmap_atomic(kaddr, KM_USER0);
1510 flush_dcache_page(dst);
1511 return;
1512
1513 }
1514 copy_user_highpage(dst, src, va, vma);
1515}
1516
1517/*
1518 * This routine handles present pages, when users try to write
1519 * to a shared page. It is done by copying the page to a new address
1520 * and decrementing the shared-page counter for the old page.
1521 *
1522 * Note that this routine assumes that the protection checks have been
1523 * done by the caller (the low-level page fault routine in most cases).
1524 * Thus we can safely just mark it writable once we've done any necessary
1525 * COW.
1526 *
1527 * We also mark the page dirty at this point even though the page will
1528 * change only once the write actually happens. This avoids a few races,
1529 * and potentially makes it more efficient.
1530 *
1531 * We enter with non-exclusive mmap_sem (to exclude vma changes,
1532 * but allow concurrent faults), with pte both mapped and locked.
1533 * We return with mmap_sem still held, but pte unmapped and unlocked.
1534 */
1535static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1536 unsigned long address, pte_t *page_table, pmd_t *pmd,
1537 spinlock_t *ptl, pte_t orig_pte)
1538{
1539 struct page *old_page, *new_page;
1540 pte_t entry;
1541 int reuse = 0, ret = VM_FAULT_MINOR;
1542 struct page *dirty_page = NULL;
1543
1544 old_page = vm_normal_page(vma, address, orig_pte);
1545 if (!old_page)
1546 goto gotten;
1547
1548 /*
1549 * Take out anonymous pages first, anonymous shared vmas are
1550 * not dirty accountable.
1551 */
1552 if (PageAnon(old_page)) {
1553 if (!TestSetPageLocked(old_page)) {
1554 reuse = can_share_swap_page(old_page);
1555 unlock_page(old_page);
1556 }
1557 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1558 (VM_WRITE|VM_SHARED))) {
1559 /*
1560 * Only catch write-faults on shared writable pages,
1561 * read-only shared pages can get COWed by
1562 * get_user_pages(.write=1, .force=1).
1563 */
1564 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1565 /*
1566 * Notify the address space that the page is about to
1567 * become writable so that it can prohibit this or wait
1568 * for the page to get into an appropriate state.
1569 *
1570 * We do this without the lock held, so that it can
1571 * sleep if it needs to.
1572 */
1573 page_cache_get(old_page);
1574 pte_unmap_unlock(page_table, ptl);
1575
1576 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
1577 goto unwritable_page;
1578
1579 /*
1580 * Since we dropped the lock we need to revalidate
1581 * the PTE as someone else may have changed it. If
1582 * they did, we just return, as we can count on the
1583 * MMU to tell us if they didn't also make it writable.
1584 */
1585 page_table = pte_offset_map_lock(mm, pmd, address,
1586 &ptl);
1587 page_cache_release(old_page);
1588 if (!pte_same(*page_table, orig_pte))
1589 goto unlock;
1590 }
1591 dirty_page = old_page;
1592 get_page(dirty_page);
1593 reuse = 1;
1594 }
1595
1596 if (reuse) {
1597 flush_cache_page(vma, address, pte_pfn(orig_pte));
1598 entry = pte_mkyoung(orig_pte);
1599 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1600 ptep_set_access_flags(vma, address, page_table, entry, 1);
1601 update_mmu_cache(vma, address, entry);
1602 lazy_mmu_prot_update(entry);
1603 ret |= VM_FAULT_WRITE;
1604 goto unlock;
1605 }
1606
1607 /*
1608 * Ok, we need to copy. Oh, well..
1609 */
1610 page_cache_get(old_page);
1611gotten:
1612 pte_unmap_unlock(page_table, ptl);
1613
1614 if (unlikely(anon_vma_prepare(vma)))
1615 goto oom;
1616 if (old_page == ZERO_PAGE(address)) {
1617 new_page = alloc_zeroed_user_highpage(vma, address);
1618 if (!new_page)
1619 goto oom;
1620 } else {
1621 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1622 if (!new_page)
1623 goto oom;
1624 cow_user_page(new_page, old_page, address, vma);
1625 }
1626
1627 /*
1628 * Re-check the pte - we dropped the lock
1629 */
1630 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1631 if (likely(pte_same(*page_table, orig_pte))) {
1632 if (old_page) {
1633 page_remove_rmap(old_page, vma);
1634 if (!PageAnon(old_page)) {
1635 dec_mm_counter(mm, file_rss);
1636 inc_mm_counter(mm, anon_rss);
1637 }
1638 } else
1639 inc_mm_counter(mm, anon_rss);
1640 flush_cache_page(vma, address, pte_pfn(orig_pte));
1641 entry = mk_pte(new_page, vma->vm_page_prot);
1642 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1643 lazy_mmu_prot_update(entry);
1644 /*
1645 * Clear the pte entry and flush it first, before updating the
1646 * pte with the new entry. This will avoid a race condition
1647 * seen in the presence of one thread doing SMC and another
1648 * thread doing COW.
1649 */
1650 ptep_clear_flush(vma, address, page_table);
1651 set_pte_at(mm, address, page_table, entry);
1652 update_mmu_cache(vma, address, entry);
1653 lru_cache_add_active(new_page);
1654 page_add_new_anon_rmap(new_page, vma, address);
1655
1656 /* Free the old page.. */
1657 new_page = old_page;
1658 ret |= VM_FAULT_WRITE;
1659 }
1660 if (new_page)
1661 page_cache_release(new_page);
1662 if (old_page)
1663 page_cache_release(old_page);
1664unlock:
1665 pte_unmap_unlock(page_table, ptl);
1666 if (dirty_page) {
1667 set_page_dirty_balance(dirty_page);
1668 put_page(dirty_page);
1669 }
1670 return ret;
1671oom:
1672 if (old_page)
1673 page_cache_release(old_page);
1674 return VM_FAULT_OOM;
1675
1676unwritable_page:
1677 page_cache_release(old_page);
1678 return VM_FAULT_SIGBUS;
1679}
1680
1681/*
1682 * Helper functions for unmap_mapping_range().
1683 *
1684 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1685 *
1686 * We have to restart searching the prio_tree whenever we drop the lock,
1687 * since the iterator is only valid while the lock is held, and anyway
1688 * a later vma might be split and reinserted earlier while lock dropped.
1689 *
1690 * The list of nonlinear vmas could be handled more efficiently, using
1691 * a placeholder, but handle it in the same way until a need is shown.
1692 * It is important to search the prio_tree before nonlinear list: a vma
1693 * may become nonlinear and be shifted from prio_tree to nonlinear list
1694 * while the lock is dropped; but never shifted from list to prio_tree.
1695 *
1696 * In order to make forward progress despite restarting the search,
1697 * vm_truncate_count is used to mark a vma as now dealt with, so we can
1698 * quickly skip it next time around. Since the prio_tree search only
1699 * shows us those vmas affected by unmapping the range in question, we
1700 * can't efficiently keep all vmas in step with mapping->truncate_count:
1701 * so instead reset them all whenever it wraps back to 0 (then go to 1).
1702 * mapping->truncate_count and vma->vm_truncate_count are protected by
1703 * i_mmap_lock.
1704 *
1705 * In order to make forward progress despite repeatedly restarting some
1706 * large vma, note the restart_addr from unmap_vmas when it breaks out:
1707 * and restart from that address when we reach that vma again. It might
1708 * have been split or merged, shrunk or extended, but never shifted: so
1709 * restart_addr remains valid so long as it remains in the vma's range.
1710 * unmap_mapping_range forces truncate_count to leap over page-aligned
1711 * values so we can save vma's restart_addr in its truncate_count field.
1712 */
1713#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1714
1715static void reset_vma_truncate_counts(struct address_space *mapping)
1716{
1717 struct vm_area_struct *vma;
1718 struct prio_tree_iter iter;
1719
1720 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1721 vma->vm_truncate_count = 0;
1722 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1723 vma->vm_truncate_count = 0;
1724}
1725
1726static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1727 unsigned long start_addr, unsigned long end_addr,
1728 struct zap_details *details)
1729{
1730 unsigned long restart_addr;
1731 int need_break;
1732
1733again:
1734 restart_addr = vma->vm_truncate_count;
1735 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1736 start_addr = restart_addr;
1737 if (start_addr >= end_addr) {
1738 /* Top of vma has been split off since last time */
1739 vma->vm_truncate_count = details->truncate_count;
1740 return 0;
1741 }
1742 }
1743
1744 restart_addr = zap_page_range(vma, start_addr,
1745 end_addr - start_addr, details);
1746 need_break = need_resched() ||
1747 need_lockbreak(details->i_mmap_lock);
1748
1749 if (restart_addr >= end_addr) {
1750 /* We have now completed this vma: mark it so */
1751 vma->vm_truncate_count = details->truncate_count;
1752 if (!need_break)
1753 return 0;
1754 } else {
1755 /* Note restart_addr in vma's truncate_count field */
1756 vma->vm_truncate_count = restart_addr;
1757 if (!need_break)
1758 goto again;
1759 }
1760
1761 spin_unlock(details->i_mmap_lock);
1762 cond_resched();
1763 spin_lock(details->i_mmap_lock);
1764 return -EINTR;
1765}
1766
1767static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1768 struct zap_details *details)
1769{
1770 struct vm_area_struct *vma;
1771 struct prio_tree_iter iter;
1772 pgoff_t vba, vea, zba, zea;
1773
1774restart:
1775 vma_prio_tree_foreach(vma, &iter, root,
1776 details->first_index, details->last_index) {
1777 /* Skip quickly over those we have already dealt with */
1778 if (vma->vm_truncate_count == details->truncate_count)
1779 continue;
1780
1781 vba = vma->vm_pgoff;
1782 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1783 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1784 zba = details->first_index;
1785 if (zba < vba)
1786 zba = vba;
1787 zea = details->last_index;
1788 if (zea > vea)
1789 zea = vea;
1790
1791 if (unmap_mapping_range_vma(vma,
1792 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1793 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1794 details) < 0)
1795 goto restart;
1796 }
1797}
1798
1799static inline void unmap_mapping_range_list(struct list_head *head,
1800 struct zap_details *details)
1801{
1802 struct vm_area_struct *vma;
1803
1804 /*
1805 * In nonlinear VMAs there is no correspondence between virtual address
1806 * offset and file offset. So we must perform an exhaustive search
1807 * across *all* the pages in each nonlinear VMA, not just the pages
1808 * whose virtual address lies outside the file truncation point.
1809 */
1810restart:
1811 list_for_each_entry(vma, head, shared.vm_set.list) {
1812 /* Skip quickly over those we have already dealt with */
1813 if (vma->vm_truncate_count == details->truncate_count)
1814 continue;
1815 details->nonlinear_vma = vma;
1816 if (unmap_mapping_range_vma(vma, vma->vm_start,
1817 vma->vm_end, details) < 0)
1818 goto restart;
1819 }
1820}
1821
1822/**
1823 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
1824 * @mapping: the address space containing mmaps to be unmapped.
1825 * @holebegin: byte in first page to unmap, relative to the start of
1826 * the underlying file. This will be rounded down to a PAGE_SIZE
1827 * boundary. Note that this is different from vmtruncate(), which
1828 * must keep the partial page. In contrast, we must get rid of
1829 * partial pages.
1830 * @holelen: size of prospective hole in bytes. This will be rounded
1831 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
1832 * end of the file.
1833 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1834 * but 0 when invalidating pagecache, don't throw away private data.
1835 */
1836void unmap_mapping_range(struct address_space *mapping,
1837 loff_t const holebegin, loff_t const holelen, int even_cows)
1838{
1839 struct zap_details details;
1840 pgoff_t hba = holebegin >> PAGE_SHIFT;
1841 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1842
1843 /* Check for overflow. */
1844 if (sizeof(holelen) > sizeof(hlen)) {
1845 long long holeend =
1846 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1847 if (holeend & ~(long long)ULONG_MAX)
1848 hlen = ULONG_MAX - hba + 1;
1849 }
1850
1851 details.check_mapping = even_cows? NULL: mapping;
1852 details.nonlinear_vma = NULL;
1853 details.first_index = hba;
1854 details.last_index = hba + hlen - 1;
1855 if (details.last_index < details.first_index)
1856 details.last_index = ULONG_MAX;
1857 details.i_mmap_lock = &mapping->i_mmap_lock;
1858
1859 spin_lock(&mapping->i_mmap_lock);
1860
1861 /* serialize i_size write against truncate_count write */
1862 smp_wmb();
1863 /* Protect against page faults, and endless unmapping loops */
1864 mapping->truncate_count++;
1865 /*
1866 * For archs where spin_lock has inclusive semantics like ia64
1867 * this smp_mb() will prevent to read pagetable contents
1868 * before the truncate_count increment is visible to
1869 * other cpus.
1870 */
1871 smp_mb();
1872 if (unlikely(is_restart_addr(mapping->truncate_count))) {
1873 if (mapping->truncate_count == 0)
1874 reset_vma_truncate_counts(mapping);
1875 mapping->truncate_count++;
1876 }
1877 details.truncate_count = mapping->truncate_count;
1878
1879 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1880 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1881 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1882 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1883 spin_unlock(&mapping->i_mmap_lock);
1884}
1885EXPORT_SYMBOL(unmap_mapping_range);
1886
1887/**
1888 * vmtruncate - unmap mappings "freed" by truncate() syscall
1889 * @inode: inode of the file used
1890 * @offset: file offset to start truncating
1891 *
1892 * NOTE! We have to be ready to update the memory sharing
1893 * between the file and the memory map for a potential last
1894 * incomplete page. Ugly, but necessary.
1895 */
1896int vmtruncate(struct inode * inode, loff_t offset)
1897{
1898 struct address_space *mapping = inode->i_mapping;
1899 unsigned long limit;
1900
1901 if (inode->i_size < offset)
1902 goto do_expand;
1903 /*
1904 * truncation of in-use swapfiles is disallowed - it would cause
1905 * subsequent swapout to scribble on the now-freed blocks.
1906 */
1907 if (IS_SWAPFILE(inode))
1908 goto out_busy;
1909 i_size_write(inode, offset);
1910 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1911 truncate_inode_pages(mapping, offset);
1912 goto out_truncate;
1913
1914do_expand:
1915 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1916 if (limit != RLIM_INFINITY && offset > limit)
1917 goto out_sig;
1918 if (offset > inode->i_sb->s_maxbytes)
1919 goto out_big;
1920 i_size_write(inode, offset);
1921
1922out_truncate:
1923 if (inode->i_op && inode->i_op->truncate)
1924 inode->i_op->truncate(inode);
1925 return 0;
1926out_sig:
1927 send_sig(SIGXFSZ, current, 0);
1928out_big:
1929 return -EFBIG;
1930out_busy:
1931 return -ETXTBSY;
1932}
1933EXPORT_SYMBOL(vmtruncate);
1934
1935int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1936{
1937 struct address_space *mapping = inode->i_mapping;
1938
1939 /*
1940 * If the underlying filesystem is not going to provide
1941 * a way to truncate a range of blocks (punch a hole) -
1942 * we should return failure right now.
1943 */
1944 if (!inode->i_op || !inode->i_op->truncate_range)
1945 return -ENOSYS;
1946
1947 mutex_lock(&inode->i_mutex);
1948 down_write(&inode->i_alloc_sem);
1949 unmap_mapping_range(mapping, offset, (end - offset), 1);
1950 truncate_inode_pages_range(mapping, offset, end);
1951 inode->i_op->truncate_range(inode, offset, end);
1952 up_write(&inode->i_alloc_sem);
1953 mutex_unlock(&inode->i_mutex);
1954
1955 return 0;
1956}
1957
1958/**
1959 * swapin_readahead - swap in pages in hope we need them soon
1960 * @entry: swap entry of this memory
1961 * @addr: address to start
1962 * @vma: user vma this addresses belong to
1963 *
1964 * Primitive swap readahead code. We simply read an aligned block of
1965 * (1 << page_cluster) entries in the swap area. This method is chosen
1966 * because it doesn't cost us any seek time. We also make sure to queue
1967 * the 'original' request together with the readahead ones...
1968 *
1969 * This has been extended to use the NUMA policies from the mm triggering
1970 * the readahead.
1971 *
1972 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1973 */
1974void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1975{
1976#ifdef CONFIG_NUMA
1977 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1978#endif
1979 int i, num;
1980 struct page *new_page;
1981 unsigned long offset;
1982
1983 /*
1984 * Get the number of handles we should do readahead io to.
1985 */
1986 num = valid_swaphandles(entry, &offset);
1987 for (i = 0; i < num; offset++, i++) {
1988 /* Ok, do the async read-ahead now */
1989 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1990 offset), vma, addr);
1991 if (!new_page)
1992 break;
1993 page_cache_release(new_page);
1994#ifdef CONFIG_NUMA
1995 /*
1996 * Find the next applicable VMA for the NUMA policy.
1997 */
1998 addr += PAGE_SIZE;
1999 if (addr == 0)
2000 vma = NULL;
2001 if (vma) {
2002 if (addr >= vma->vm_end) {
2003 vma = next_vma;
2004 next_vma = vma ? vma->vm_next : NULL;
2005 }
2006 if (vma && addr < vma->vm_start)
2007 vma = NULL;
2008 } else {
2009 if (next_vma && addr >= next_vma->vm_start) {
2010 vma = next_vma;
2011 next_vma = vma->vm_next;
2012 }
2013 }
2014#endif
2015 }
2016 lru_add_drain(); /* Push any new pages onto the LRU now */
2017}
2018
2019/*
2020 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2021 * but allow concurrent faults), and pte mapped but not yet locked.
2022 * We return with mmap_sem still held, but pte unmapped and unlocked.
2023 */
2024static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2025 unsigned long address, pte_t *page_table, pmd_t *pmd,
2026 int write_access, pte_t orig_pte)
2027{
2028 spinlock_t *ptl;
2029 struct page *page;
2030 swp_entry_t entry;
2031 pte_t pte;
2032 int ret = VM_FAULT_MINOR;
2033
2034 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2035 goto out;
2036
2037 entry = pte_to_swp_entry(orig_pte);
2038 if (is_migration_entry(entry)) {
2039 migration_entry_wait(mm, pmd, address);
2040 goto out;
2041 }
2042 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2043 page = lookup_swap_cache(entry);
2044 if (!page) {
2045 grab_swap_token(); /* Contend for token _before_ read-in */
2046 swapin_readahead(entry, address, vma);
2047 page = read_swap_cache_async(entry, vma, address);
2048 if (!page) {
2049 /*
2050 * Back out if somebody else faulted in this pte
2051 * while we released the pte lock.
2052 */
2053 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2054 if (likely(pte_same(*page_table, orig_pte)))
2055 ret = VM_FAULT_OOM;
2056 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2057 goto unlock;
2058 }
2059
2060 /* Had to read the page from swap area: Major fault */
2061 ret = VM_FAULT_MAJOR;
2062 count_vm_event(PGMAJFAULT);
2063 }
2064
2065 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2066 mark_page_accessed(page);
2067 lock_page(page);
2068
2069 /*
2070 * Back out if somebody else already faulted in this pte.
2071 */
2072 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2073 if (unlikely(!pte_same(*page_table, orig_pte)))
2074 goto out_nomap;
2075
2076 if (unlikely(!PageUptodate(page))) {
2077 ret = VM_FAULT_SIGBUS;
2078 goto out_nomap;
2079 }
2080
2081 /* The page isn't present yet, go ahead with the fault. */
2082
2083 inc_mm_counter(mm, anon_rss);
2084 pte = mk_pte(page, vma->vm_page_prot);
2085 if (write_access && can_share_swap_page(page)) {
2086 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2087 write_access = 0;
2088 }
2089
2090 flush_icache_page(vma, page);
2091 set_pte_at(mm, address, page_table, pte);
2092 page_add_anon_rmap(page, vma, address);
2093
2094 swap_free(entry);
2095 if (vm_swap_full())
2096 remove_exclusive_swap_page(page);
2097 unlock_page(page);
2098
2099 if (write_access) {
2100 if (do_wp_page(mm, vma, address,
2101 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
2102 ret = VM_FAULT_OOM;
2103 goto out;
2104 }
2105
2106 /* No need to invalidate - it was non-present before */
2107 update_mmu_cache(vma, address, pte);
2108 lazy_mmu_prot_update(pte);
2109unlock:
2110 pte_unmap_unlock(page_table, ptl);
2111out:
2112 return ret;
2113out_nomap:
2114 pte_unmap_unlock(page_table, ptl);
2115 unlock_page(page);
2116 page_cache_release(page);
2117 return ret;
2118}
2119
2120/*
2121 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2122 * but allow concurrent faults), and pte mapped but not yet locked.
2123 * We return with mmap_sem still held, but pte unmapped and unlocked.
2124 */
2125static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2126 unsigned long address, pte_t *page_table, pmd_t *pmd,
2127 int write_access)
2128{
2129 struct page *page;
2130 spinlock_t *ptl;
2131 pte_t entry;
2132
2133 if (write_access) {
2134 /* Allocate our own private page. */
2135 pte_unmap(page_table);
2136
2137 if (unlikely(anon_vma_prepare(vma)))
2138 goto oom;
2139 page = alloc_zeroed_user_highpage(vma, address);
2140 if (!page)
2141 goto oom;
2142
2143 entry = mk_pte(page, vma->vm_page_prot);
2144 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2145
2146 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2147 if (!pte_none(*page_table))
2148 goto release;
2149 inc_mm_counter(mm, anon_rss);
2150 lru_cache_add_active(page);
2151 page_add_new_anon_rmap(page, vma, address);
2152 } else {
2153 /* Map the ZERO_PAGE - vm_page_prot is readonly */
2154 page = ZERO_PAGE(address);
2155 page_cache_get(page);
2156 entry = mk_pte(page, vma->vm_page_prot);
2157
2158 ptl = pte_lockptr(mm, pmd);
2159 spin_lock(ptl);
2160 if (!pte_none(*page_table))
2161 goto release;
2162 inc_mm_counter(mm, file_rss);
2163 page_add_file_rmap(page);
2164 }
2165
2166 set_pte_at(mm, address, page_table, entry);
2167
2168 /* No need to invalidate - it was non-present before */
2169 update_mmu_cache(vma, address, entry);
2170 lazy_mmu_prot_update(entry);
2171unlock:
2172 pte_unmap_unlock(page_table, ptl);
2173 return VM_FAULT_MINOR;
2174release:
2175 page_cache_release(page);
2176 goto unlock;
2177oom:
2178 return VM_FAULT_OOM;
2179}
2180
2181/*
2182 * do_no_page() tries to create a new page mapping. It aggressively
2183 * tries to share with existing pages, but makes a separate copy if
2184 * the "write_access" parameter is true in order to avoid the next
2185 * page fault.
2186 *
2187 * As this is called only for pages that do not currently exist, we
2188 * do not need to flush old virtual caches or the TLB.
2189 *
2190 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2191 * but allow concurrent faults), and pte mapped but not yet locked.
2192 * We return with mmap_sem still held, but pte unmapped and unlocked.
2193 */
2194static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2195 unsigned long address, pte_t *page_table, pmd_t *pmd,
2196 int write_access)
2197{
2198 spinlock_t *ptl;
2199 struct page *new_page;
2200 struct address_space *mapping = NULL;
2201 pte_t entry;
2202 unsigned int sequence = 0;
2203 int ret = VM_FAULT_MINOR;
2204 int anon = 0;
2205 struct page *dirty_page = NULL;
2206
2207 pte_unmap(page_table);
2208 BUG_ON(vma->vm_flags & VM_PFNMAP);
2209
2210 if (vma->vm_file) {
2211 mapping = vma->vm_file->f_mapping;
2212 sequence = mapping->truncate_count;
2213 smp_rmb(); /* serializes i_size against truncate_count */
2214 }
2215retry:
2216 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2217 /*
2218 * No smp_rmb is needed here as long as there's a full
2219 * spin_lock/unlock sequence inside the ->nopage callback
2220 * (for the pagecache lookup) that acts as an implicit
2221 * smp_mb() and prevents the i_size read to happen
2222 * after the next truncate_count read.
2223 */
2224
2225 /* no page was available -- either SIGBUS, OOM or REFAULT */
2226 if (unlikely(new_page == NOPAGE_SIGBUS))
2227 return VM_FAULT_SIGBUS;
2228 else if (unlikely(new_page == NOPAGE_OOM))
2229 return VM_FAULT_OOM;
2230 else if (unlikely(new_page == NOPAGE_REFAULT))
2231 return VM_FAULT_MINOR;
2232
2233 /*
2234 * Should we do an early C-O-W break?
2235 */
2236 if (write_access) {
2237 if (!(vma->vm_flags & VM_SHARED)) {
2238 struct page *page;
2239
2240 if (unlikely(anon_vma_prepare(vma)))
2241 goto oom;
2242 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
2243 if (!page)
2244 goto oom;
2245 copy_user_highpage(page, new_page, address, vma);
2246 page_cache_release(new_page);
2247 new_page = page;
2248 anon = 1;
2249
2250 } else {
2251 /* if the page will be shareable, see if the backing
2252 * address space wants to know that the page is about
2253 * to become writable */
2254 if (vma->vm_ops->page_mkwrite &&
2255 vma->vm_ops->page_mkwrite(vma, new_page) < 0
2256 ) {
2257 page_cache_release(new_page);
2258 return VM_FAULT_SIGBUS;
2259 }
2260 }
2261 }
2262
2263 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2264 /*
2265 * For a file-backed vma, someone could have truncated or otherwise
2266 * invalidated this page. If unmap_mapping_range got called,
2267 * retry getting the page.
2268 */
2269 if (mapping && unlikely(sequence != mapping->truncate_count)) {
2270 pte_unmap_unlock(page_table, ptl);
2271 page_cache_release(new_page);
2272 cond_resched();
2273 sequence = mapping->truncate_count;
2274 smp_rmb();
2275 goto retry;
2276 }
2277
2278 /*
2279 * This silly early PAGE_DIRTY setting removes a race
2280 * due to the bad i386 page protection. But it's valid
2281 * for other architectures too.
2282 *
2283 * Note that if write_access is true, we either now have
2284 * an exclusive copy of the page, or this is a shared mapping,
2285 * so we can make it writable and dirty to avoid having to
2286 * handle that later.
2287 */
2288 /* Only go through if we didn't race with anybody else... */
2289 if (pte_none(*page_table)) {
2290 flush_icache_page(vma, new_page);
2291 entry = mk_pte(new_page, vma->vm_page_prot);
2292 if (write_access)
2293 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2294 set_pte_at(mm, address, page_table, entry);
2295 if (anon) {
2296 inc_mm_counter(mm, anon_rss);
2297 lru_cache_add_active(new_page);
2298 page_add_new_anon_rmap(new_page, vma, address);
2299 } else {
2300 inc_mm_counter(mm, file_rss);
2301 page_add_file_rmap(new_page);
2302 if (write_access) {
2303 dirty_page = new_page;
2304 get_page(dirty_page);
2305 }
2306 }
2307 } else {
2308 /* One of our sibling threads was faster, back out. */
2309 page_cache_release(new_page);
2310 goto unlock;
2311 }
2312
2313 /* no need to invalidate: a not-present page shouldn't be cached */
2314 update_mmu_cache(vma, address, entry);
2315 lazy_mmu_prot_update(entry);
2316unlock:
2317 pte_unmap_unlock(page_table, ptl);
2318 if (dirty_page) {
2319 set_page_dirty_balance(dirty_page);
2320 put_page(dirty_page);
2321 }
2322 return ret;
2323oom:
2324 page_cache_release(new_page);
2325 return VM_FAULT_OOM;
2326}
2327
2328/*
2329 * do_no_pfn() tries to create a new page mapping for a page without
2330 * a struct_page backing it
2331 *
2332 * As this is called only for pages that do not currently exist, we
2333 * do not need to flush old virtual caches or the TLB.
2334 *
2335 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2336 * but allow concurrent faults), and pte mapped but not yet locked.
2337 * We return with mmap_sem still held, but pte unmapped and unlocked.
2338 *
2339 * It is expected that the ->nopfn handler always returns the same pfn
2340 * for a given virtual mapping.
2341 *
2342 * Mark this `noinline' to prevent it from bloating the main pagefault code.
2343 */
2344static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
2345 unsigned long address, pte_t *page_table, pmd_t *pmd,
2346 int write_access)
2347{
2348 spinlock_t *ptl;
2349 pte_t entry;
2350 unsigned long pfn;
2351 int ret = VM_FAULT_MINOR;
2352
2353 pte_unmap(page_table);
2354 BUG_ON(!(vma->vm_flags & VM_PFNMAP));
2355 BUG_ON(is_cow_mapping(vma->vm_flags));
2356
2357 pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2358 if (unlikely(pfn == NOPFN_OOM))
2359 return VM_FAULT_OOM;
2360 else if (unlikely(pfn == NOPFN_SIGBUS))
2361 return VM_FAULT_SIGBUS;
2362 else if (unlikely(pfn == NOPFN_REFAULT))
2363 return VM_FAULT_MINOR;
2364
2365 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2366
2367 /* Only go through if we didn't race with anybody else... */
2368 if (pte_none(*page_table)) {
2369 entry = pfn_pte(pfn, vma->vm_page_prot);
2370 if (write_access)
2371 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2372 set_pte_at(mm, address, page_table, entry);
2373 }
2374 pte_unmap_unlock(page_table, ptl);
2375 return ret;
2376}
2377
2378/*
2379 * Fault of a previously existing named mapping. Repopulate the pte
2380 * from the encoded file_pte if possible. This enables swappable
2381 * nonlinear vmas.
2382 *
2383 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2384 * but allow concurrent faults), and pte mapped but not yet locked.
2385 * We return with mmap_sem still held, but pte unmapped and unlocked.
2386 */
2387static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
2388 unsigned long address, pte_t *page_table, pmd_t *pmd,
2389 int write_access, pte_t orig_pte)
2390{
2391 pgoff_t pgoff;
2392 int err;
2393
2394 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2395 return VM_FAULT_MINOR;
2396
2397 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2398 /*
2399 * Page table corrupted: show pte and kill process.
2400 */
2401 print_bad_pte(vma, orig_pte, address);
2402 return VM_FAULT_OOM;
2403 }
2404 /* We can then assume vm->vm_ops && vma->vm_ops->populate */
2405
2406 pgoff = pte_to_pgoff(orig_pte);
2407 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
2408 vma->vm_page_prot, pgoff, 0);
2409 if (err == -ENOMEM)
2410 return VM_FAULT_OOM;
2411 if (err)
2412 return VM_FAULT_SIGBUS;
2413 return VM_FAULT_MAJOR;
2414}
2415
2416/*
2417 * These routines also need to handle stuff like marking pages dirty
2418 * and/or accessed for architectures that don't do it in hardware (most
2419 * RISC architectures). The early dirtying is also good on the i386.
2420 *
2421 * There is also a hook called "update_mmu_cache()" that architectures
2422 * with external mmu caches can use to update those (ie the Sparc or
2423 * PowerPC hashed page tables that act as extended TLBs).
2424 *
2425 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2426 * but allow concurrent faults), and pte mapped but not yet locked.
2427 * We return with mmap_sem still held, but pte unmapped and unlocked.
2428 */
2429static inline int handle_pte_fault(struct mm_struct *mm,
2430 struct vm_area_struct *vma, unsigned long address,
2431 pte_t *pte, pmd_t *pmd, int write_access)
2432{
2433 pte_t entry;
2434 pte_t old_entry;
2435 spinlock_t *ptl;
2436
2437 old_entry = entry = *pte;
2438 if (!pte_present(entry)) {
2439 if (pte_none(entry)) {
2440 if (vma->vm_ops) {
2441 if (vma->vm_ops->nopage)
2442 return do_no_page(mm, vma, address,
2443 pte, pmd,
2444 write_access);
2445 if (unlikely(vma->vm_ops->nopfn))
2446 return do_no_pfn(mm, vma, address, pte,
2447 pmd, write_access);
2448 }
2449 return do_anonymous_page(mm, vma, address,
2450 pte, pmd, write_access);
2451 }
2452 if (pte_file(entry))
2453 return do_file_page(mm, vma, address,
2454 pte, pmd, write_access, entry);
2455 return do_swap_page(mm, vma, address,
2456 pte, pmd, write_access, entry);
2457 }
2458
2459 ptl = pte_lockptr(mm, pmd);
2460 spin_lock(ptl);
2461 if (unlikely(!pte_same(*pte, entry)))
2462 goto unlock;
2463 if (write_access) {
2464 if (!pte_write(entry))
2465 return do_wp_page(mm, vma, address,
2466 pte, pmd, ptl, entry);
2467 entry = pte_mkdirty(entry);
2468 }
2469 entry = pte_mkyoung(entry);
2470 if (!pte_same(old_entry, entry)) {
2471 ptep_set_access_flags(vma, address, pte, entry, write_access);
2472 update_mmu_cache(vma, address, entry);
2473 lazy_mmu_prot_update(entry);
2474 } else {
2475 /*
2476 * This is needed only for protection faults but the arch code
2477 * is not yet telling us if this is a protection fault or not.
2478 * This still avoids useless tlb flushes for .text page faults
2479 * with threads.
2480 */
2481 if (write_access)
2482 flush_tlb_page(vma, address);
2483 }
2484unlock:
2485 pte_unmap_unlock(pte, ptl);
2486 return VM_FAULT_MINOR;
2487}
2488
2489/*
2490 * By the time we get here, we already hold the mm semaphore
2491 */
2492int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2493 unsigned long address, int write_access)
2494{
2495 pgd_t *pgd;
2496 pud_t *pud;
2497 pmd_t *pmd;
2498 pte_t *pte;
2499
2500 __set_current_state(TASK_RUNNING);
2501
2502 count_vm_event(PGFAULT);
2503
2504 if (unlikely(is_vm_hugetlb_page(vma)))
2505 return hugetlb_fault(mm, vma, address, write_access);
2506
2507 pgd = pgd_offset(mm, address);
2508 pud = pud_alloc(mm, pgd, address);
2509 if (!pud)
2510 return VM_FAULT_OOM;
2511 pmd = pmd_alloc(mm, pud, address);
2512 if (!pmd)
2513 return VM_FAULT_OOM;
2514 pte = pte_alloc_map(mm, pmd, address);
2515 if (!pte)
2516 return VM_FAULT_OOM;
2517
2518 return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2519}
2520
2521EXPORT_SYMBOL_GPL(__handle_mm_fault);
2522
2523#ifndef __PAGETABLE_PUD_FOLDED
2524/*
2525 * Allocate page upper directory.
2526 * We've already handled the fast-path in-line.
2527 */
2528int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2529{
2530 pud_t *new = pud_alloc_one(mm, address);
2531 if (!new)
2532 return -ENOMEM;
2533
2534 spin_lock(&mm->page_table_lock);
2535 if (pgd_present(*pgd)) /* Another has populated it */
2536 pud_free(new);
2537 else
2538 pgd_populate(mm, pgd, new);
2539 spin_unlock(&mm->page_table_lock);
2540 return 0;
2541}
2542#else
2543/* Workaround for gcc 2.96 */
2544int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2545{
2546 return 0;
2547}
2548#endif /* __PAGETABLE_PUD_FOLDED */
2549
2550#ifndef __PAGETABLE_PMD_FOLDED
2551/*
2552 * Allocate page middle directory.
2553 * We've already handled the fast-path in-line.
2554 */
2555int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2556{
2557 pmd_t *new = pmd_alloc_one(mm, address);
2558 if (!new)
2559 return -ENOMEM;
2560
2561 spin_lock(&mm->page_table_lock);
2562#ifndef __ARCH_HAS_4LEVEL_HACK
2563 if (pud_present(*pud)) /* Another has populated it */
2564 pmd_free(new);
2565 else
2566 pud_populate(mm, pud, new);
2567#else
2568 if (pgd_present(*pud)) /* Another has populated it */
2569 pmd_free(new);
2570 else
2571 pgd_populate(mm, pud, new);
2572#endif /* __ARCH_HAS_4LEVEL_HACK */
2573 spin_unlock(&mm->page_table_lock);
2574 return 0;
2575}
2576#else
2577/* Workaround for gcc 2.96 */
2578int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2579{
2580 return 0;
2581}
2582#endif /* __PAGETABLE_PMD_FOLDED */
2583
2584int make_pages_present(unsigned long addr, unsigned long end)
2585{
2586 int ret, len, write;
2587 struct vm_area_struct * vma;
2588
2589 vma = find_vma(current->mm, addr);
2590 if (!vma)
2591 return -1;
2592 write = (vma->vm_flags & VM_WRITE) != 0;
2593 BUG_ON(addr >= end);
2594 BUG_ON(end > vma->vm_end);
2595 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2596 ret = get_user_pages(current, current->mm, addr,
2597 len, write, 0, NULL, NULL);
2598 if (ret < 0)
2599 return ret;
2600 return ret == len ? 0 : -1;
2601}
2602
2603/*
2604 * Map a vmalloc()-space virtual address to the physical page.
2605 */
2606struct page * vmalloc_to_page(void * vmalloc_addr)
2607{
2608 unsigned long addr = (unsigned long) vmalloc_addr;
2609 struct page *page = NULL;
2610 pgd_t *pgd = pgd_offset_k(addr);
2611 pud_t *pud;
2612 pmd_t *pmd;
2613 pte_t *ptep, pte;
2614
2615 if (!pgd_none(*pgd)) {
2616 pud = pud_offset(pgd, addr);
2617 if (!pud_none(*pud)) {
2618 pmd = pmd_offset(pud, addr);
2619 if (!pmd_none(*pmd)) {
2620 ptep = pte_offset_map(pmd, addr);
2621 pte = *ptep;
2622 if (pte_present(pte))
2623 page = pte_page(pte);
2624 pte_unmap(ptep);
2625 }
2626 }
2627 }
2628 return page;
2629}
2630
2631EXPORT_SYMBOL(vmalloc_to_page);
2632
2633/*
2634 * Map a vmalloc()-space virtual address to the physical page frame number.
2635 */
2636unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2637{
2638 return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2639}
2640
2641EXPORT_SYMBOL(vmalloc_to_pfn);
2642
2643#if !defined(__HAVE_ARCH_GATE_AREA)
2644
2645#if defined(AT_SYSINFO_EHDR)
2646static struct vm_area_struct gate_vma;
2647
2648static int __init gate_vma_init(void)
2649{
2650 gate_vma.vm_mm = NULL;
2651 gate_vma.vm_start = FIXADDR_USER_START;
2652 gate_vma.vm_end = FIXADDR_USER_END;
2653 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
2654 gate_vma.vm_page_prot = __P101;
2655 /*
2656 * Make sure the vDSO gets into every core dump.
2657 * Dumping its contents makes post-mortem fully interpretable later
2658 * without matching up the same kernel and hardware config to see
2659 * what PC values meant.
2660 */
2661 gate_vma.vm_flags |= VM_ALWAYSDUMP;
2662 return 0;
2663}
2664__initcall(gate_vma_init);
2665#endif
2666
2667struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2668{
2669#ifdef AT_SYSINFO_EHDR
2670 return &gate_vma;
2671#else
2672 return NULL;
2673#endif
2674}
2675
2676int in_gate_area_no_task(unsigned long addr)
2677{
2678#ifdef AT_SYSINFO_EHDR
2679 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2680 return 1;
2681#endif
2682 return 0;
2683}
2684
2685#endif /* __HAVE_ARCH_GATE_AREA */
2686
2687/*
2688 * Access another process' address space.
2689 * Source/target buffer must be kernel space,
2690 * Do not walk the page table directly, use get_user_pages
2691 */
2692int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2693{
2694 struct mm_struct *mm;
2695 struct vm_area_struct *vma;
2696 struct page *page;
2697 void *old_buf = buf;
2698
2699 mm = get_task_mm(tsk);
2700 if (!mm)
2701 return 0;
2702
2703 down_read(&mm->mmap_sem);
2704 /* ignore errors, just check how much was sucessfully transfered */
2705 while (len) {
2706 int bytes, ret, offset;
2707 void *maddr;
2708
2709 ret = get_user_pages(tsk, mm, addr, 1,
2710 write, 1, &page, &vma);
2711 if (ret <= 0)
2712 break;
2713
2714 bytes = len;
2715 offset = addr & (PAGE_SIZE-1);
2716 if (bytes > PAGE_SIZE-offset)
2717 bytes = PAGE_SIZE-offset;
2718
2719 maddr = kmap(page);
2720 if (write) {
2721 copy_to_user_page(vma, page, addr,
2722 maddr + offset, buf, bytes);
2723 set_page_dirty_lock(page);
2724 } else {
2725 copy_from_user_page(vma, page, addr,
2726 buf, maddr + offset, bytes);
2727 }
2728 kunmap(page);
2729 page_cache_release(page);
2730 len -= bytes;
2731 buf += bytes;
2732 addr += bytes;
2733 }
2734 up_read(&mm->mmap_sem);
2735 mmput(mm);
2736
2737 return buf - old_buf;
2738}