9cf3f341a28a6cf4c53af58f01959a9cf7c23eb1
[linux-2.6.git] / mm / memory.c
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *              Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *              (Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/rmap.h>
49 #include <linux/module.h>
50 #include <linux/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 */
65 unsigned long max_mapnr;
66 struct page *mem_map;
67
68 EXPORT_SYMBOL(max_mapnr);
69 EXPORT_SYMBOL(mem_map);
70 #endif
71
72 unsigned 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  */
80 void * high_memory;
81 unsigned long vmalloc_earlyreserve;
82
83 EXPORT_SYMBOL(num_physpages);
84 EXPORT_SYMBOL(high_memory);
85 EXPORT_SYMBOL(vmalloc_earlyreserve);
86
87 int randomize_va_space __read_mostly = 1;
88
89 static 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
103 void pgd_clear_bad(pgd_t *pgd)
104 {
105         pgd_ERROR(*pgd);
106         pgd_clear(pgd);
107 }
108
109 void pud_clear_bad(pud_t *pud)
110 {
111         pud_ERROR(*pud);
112         pud_clear(pud);
113 }
114
115 void 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  */
125 static 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
135 static 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
168 static 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  */
206 void 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
269 void 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
303 int __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
323 int __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
338 static 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  */
353 void 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
363 static 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  */
388 struct 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
427 static inline void
428 copy_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
488 out_set_pte:
489         set_pte_at(dst_mm, addr, dst_pte, pte);
490 }
491
492 static 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
501 again:
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
542 static 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
564 static 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
586 int 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
621 static 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                                         mark_page_accessed(page);
682                                 file_rss--;
683                         }
684                         page_remove_rmap(page);
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
706 static 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
728 static 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
750 static 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  */
811 unsigned 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         }
872 out:
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  */
883 unsigned 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  */
903 struct 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         }
960 unlock:
961         pte_unmap_unlock(ptep, ptl);
962 out:
963         return page;
964
965 no_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
979 int 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                         }
1090                         if (pages) {
1091                                 pages[i] = page;
1092
1093                                 flush_anon_page(page, start);
1094                                 flush_dcache_page(page);
1095                         }
1096                         if (vmas)
1097                                 vmas[i] = vma;
1098                         i++;
1099                         start += PAGE_SIZE;
1100                         len--;
1101                 } while (len && start < vma->vm_end);
1102         } while (len);
1103         return i;
1104 }
1105 EXPORT_SYMBOL(get_user_pages);
1106
1107 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1108                         unsigned long addr, unsigned long end, pgprot_t prot)
1109 {
1110         pte_t *pte;
1111         spinlock_t *ptl;
1112
1113         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1114         if (!pte)
1115                 return -ENOMEM;
1116         arch_enter_lazy_mmu_mode();
1117         do {
1118                 struct page *page = ZERO_PAGE(addr);
1119                 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1120                 page_cache_get(page);
1121                 page_add_file_rmap(page);
1122                 inc_mm_counter(mm, file_rss);
1123                 BUG_ON(!pte_none(*pte));
1124                 set_pte_at(mm, addr, pte, zero_pte);
1125         } while (pte++, addr += PAGE_SIZE, addr != end);
1126         arch_leave_lazy_mmu_mode();
1127         pte_unmap_unlock(pte - 1, ptl);
1128         return 0;
1129 }
1130
1131 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1132                         unsigned long addr, unsigned long end, pgprot_t prot)
1133 {
1134         pmd_t *pmd;
1135         unsigned long next;
1136
1137         pmd = pmd_alloc(mm, pud, addr);
1138         if (!pmd)
1139                 return -ENOMEM;
1140         do {
1141                 next = pmd_addr_end(addr, end);
1142                 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1143                         return -ENOMEM;
1144         } while (pmd++, addr = next, addr != end);
1145         return 0;
1146 }
1147
1148 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1149                         unsigned long addr, unsigned long end, pgprot_t prot)
1150 {
1151         pud_t *pud;
1152         unsigned long next;
1153
1154         pud = pud_alloc(mm, pgd, addr);
1155         if (!pud)
1156                 return -ENOMEM;
1157         do {
1158                 next = pud_addr_end(addr, end);
1159                 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1160                         return -ENOMEM;
1161         } while (pud++, addr = next, addr != end);
1162         return 0;
1163 }
1164
1165 int zeromap_page_range(struct vm_area_struct *vma,
1166                         unsigned long addr, unsigned long size, pgprot_t prot)
1167 {
1168         pgd_t *pgd;
1169         unsigned long next;
1170         unsigned long end = addr + size;
1171         struct mm_struct *mm = vma->vm_mm;
1172         int err;
1173
1174         BUG_ON(addr >= end);
1175         pgd = pgd_offset(mm, addr);
1176         flush_cache_range(vma, addr, end);
1177         do {
1178                 next = pgd_addr_end(addr, end);
1179                 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1180                 if (err)
1181                         break;
1182         } while (pgd++, addr = next, addr != end);
1183         return err;
1184 }
1185
1186 pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl)
1187 {
1188         pgd_t * pgd = pgd_offset(mm, addr);
1189         pud_t * pud = pud_alloc(mm, pgd, addr);
1190         if (pud) {
1191                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1192                 if (pmd)
1193                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1194         }
1195         return NULL;
1196 }
1197
1198 /*
1199  * This is the old fallback for page remapping.
1200  *
1201  * For historical reasons, it only allows reserved pages. Only
1202  * old drivers should use this, and they needed to mark their
1203  * pages reserved for the old functions anyway.
1204  */
1205 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1206 {
1207         int retval;
1208         pte_t *pte;
1209         spinlock_t *ptl;  
1210
1211         retval = -EINVAL;
1212         if (PageAnon(page))
1213                 goto out;
1214         retval = -ENOMEM;
1215         flush_dcache_page(page);
1216         pte = get_locked_pte(mm, addr, &ptl);
1217         if (!pte)
1218                 goto out;
1219         retval = -EBUSY;
1220         if (!pte_none(*pte))
1221                 goto out_unlock;
1222
1223         /* Ok, finally just insert the thing.. */
1224         get_page(page);
1225         inc_mm_counter(mm, file_rss);
1226         page_add_file_rmap(page);
1227         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1228
1229         retval = 0;
1230 out_unlock:
1231         pte_unmap_unlock(pte, ptl);
1232 out:
1233         return retval;
1234 }
1235
1236 /**
1237  * vm_insert_page - insert single page into user vma
1238  * @vma: user vma to map to
1239  * @addr: target user address of this page
1240  * @page: source kernel page
1241  *
1242  * This allows drivers to insert individual pages they've allocated
1243  * into a user vma.
1244  *
1245  * The page has to be a nice clean _individual_ kernel allocation.
1246  * If you allocate a compound page, you need to have marked it as
1247  * such (__GFP_COMP), or manually just split the page up yourself
1248  * (see split_page()).
1249  *
1250  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1251  * took an arbitrary page protection parameter. This doesn't allow
1252  * that. Your vma protection will have to be set up correctly, which
1253  * means that if you want a shared writable mapping, you'd better
1254  * ask for a shared writable mapping!
1255  *
1256  * The page does not need to be reserved.
1257  */
1258 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1259 {
1260         if (addr < vma->vm_start || addr >= vma->vm_end)
1261                 return -EFAULT;
1262         if (!page_count(page))
1263                 return -EINVAL;
1264         vma->vm_flags |= VM_INSERTPAGE;
1265         return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1266 }
1267 EXPORT_SYMBOL(vm_insert_page);
1268
1269 /*
1270  * maps a range of physical memory into the requested pages. the old
1271  * mappings are removed. any references to nonexistent pages results
1272  * in null mappings (currently treated as "copy-on-access")
1273  */
1274 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1275                         unsigned long addr, unsigned long end,
1276                         unsigned long pfn, pgprot_t prot)
1277 {
1278         pte_t *pte;
1279         spinlock_t *ptl;
1280
1281         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1282         if (!pte)
1283                 return -ENOMEM;
1284         arch_enter_lazy_mmu_mode();
1285         do {
1286                 BUG_ON(!pte_none(*pte));
1287                 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1288                 pfn++;
1289         } while (pte++, addr += PAGE_SIZE, addr != end);
1290         arch_leave_lazy_mmu_mode();
1291         pte_unmap_unlock(pte - 1, ptl);
1292         return 0;
1293 }
1294
1295 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1296                         unsigned long addr, unsigned long end,
1297                         unsigned long pfn, pgprot_t prot)
1298 {
1299         pmd_t *pmd;
1300         unsigned long next;
1301
1302         pfn -= addr >> PAGE_SHIFT;
1303         pmd = pmd_alloc(mm, pud, addr);
1304         if (!pmd)
1305                 return -ENOMEM;
1306         do {
1307                 next = pmd_addr_end(addr, end);
1308                 if (remap_pte_range(mm, pmd, addr, next,
1309                                 pfn + (addr >> PAGE_SHIFT), prot))
1310                         return -ENOMEM;
1311         } while (pmd++, addr = next, addr != end);
1312         return 0;
1313 }
1314
1315 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1316                         unsigned long addr, unsigned long end,
1317                         unsigned long pfn, pgprot_t prot)
1318 {
1319         pud_t *pud;
1320         unsigned long next;
1321
1322         pfn -= addr >> PAGE_SHIFT;
1323         pud = pud_alloc(mm, pgd, addr);
1324         if (!pud)
1325                 return -ENOMEM;
1326         do {
1327                 next = pud_addr_end(addr, end);
1328                 if (remap_pmd_range(mm, pud, addr, next,
1329                                 pfn + (addr >> PAGE_SHIFT), prot))
1330                         return -ENOMEM;
1331         } while (pud++, addr = next, addr != end);
1332         return 0;
1333 }
1334
1335 /**
1336  * remap_pfn_range - remap kernel memory to userspace
1337  * @vma: user vma to map to
1338  * @addr: target user address to start at
1339  * @pfn: physical address of kernel memory
1340  * @size: size of map area
1341  * @prot: page protection flags for this mapping
1342  *
1343  *  Note: this is only safe if the mm semaphore is held when called.
1344  */
1345 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1346                     unsigned long pfn, unsigned long size, pgprot_t prot)
1347 {
1348         pgd_t *pgd;
1349         unsigned long next;
1350         unsigned long end = addr + PAGE_ALIGN(size);
1351         struct mm_struct *mm = vma->vm_mm;
1352         int err;
1353
1354         /*
1355          * Physically remapped pages are special. Tell the
1356          * rest of the world about it:
1357          *   VM_IO tells people not to look at these pages
1358          *      (accesses can have side effects).
1359          *   VM_RESERVED is specified all over the place, because
1360          *      in 2.4 it kept swapout's vma scan off this vma; but
1361          *      in 2.6 the LRU scan won't even find its pages, so this
1362          *      flag means no more than count its pages in reserved_vm,
1363          *      and omit it from core dump, even when VM_IO turned off.
1364          *   VM_PFNMAP tells the core MM that the base pages are just
1365          *      raw PFN mappings, and do not have a "struct page" associated
1366          *      with them.
1367          *
1368          * There's a horrible special case to handle copy-on-write
1369          * behaviour that some programs depend on. We mark the "original"
1370          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1371          */
1372         if (is_cow_mapping(vma->vm_flags)) {
1373                 if (addr != vma->vm_start || end != vma->vm_end)
1374                         return -EINVAL;
1375                 vma->vm_pgoff = pfn;
1376         }
1377
1378         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1379
1380         BUG_ON(addr >= end);
1381         pfn -= addr >> PAGE_SHIFT;
1382         pgd = pgd_offset(mm, addr);
1383         flush_cache_range(vma, addr, end);
1384         do {
1385                 next = pgd_addr_end(addr, end);
1386                 err = remap_pud_range(mm, pgd, addr, next,
1387                                 pfn + (addr >> PAGE_SHIFT), prot);
1388                 if (err)
1389                         break;
1390         } while (pgd++, addr = next, addr != end);
1391         return err;
1392 }
1393 EXPORT_SYMBOL(remap_pfn_range);
1394
1395 /*
1396  * handle_pte_fault chooses page fault handler according to an entry
1397  * which was read non-atomically.  Before making any commitment, on
1398  * those architectures or configurations (e.g. i386 with PAE) which
1399  * might give a mix of unmatched parts, do_swap_page and do_file_page
1400  * must check under lock before unmapping the pte and proceeding
1401  * (but do_wp_page is only called after already making such a check;
1402  * and do_anonymous_page and do_no_page can safely check later on).
1403  */
1404 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1405                                 pte_t *page_table, pte_t orig_pte)
1406 {
1407         int same = 1;
1408 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1409         if (sizeof(pte_t) > sizeof(unsigned long)) {
1410                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1411                 spin_lock(ptl);
1412                 same = pte_same(*page_table, orig_pte);
1413                 spin_unlock(ptl);
1414         }
1415 #endif
1416         pte_unmap(page_table);
1417         return same;
1418 }
1419
1420 /*
1421  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1422  * servicing faults for write access.  In the normal case, do always want
1423  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1424  * that do not have writing enabled, when used by access_process_vm.
1425  */
1426 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1427 {
1428         if (likely(vma->vm_flags & VM_WRITE))
1429                 pte = pte_mkwrite(pte);
1430         return pte;
1431 }
1432
1433 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1434 {
1435         /*
1436          * If the source page was a PFN mapping, we don't have
1437          * a "struct page" for it. We do a best-effort copy by
1438          * just copying from the original user address. If that
1439          * fails, we just zero-fill it. Live with it.
1440          */
1441         if (unlikely(!src)) {
1442                 void *kaddr = kmap_atomic(dst, KM_USER0);
1443                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1444
1445                 /*
1446                  * This really shouldn't fail, because the page is there
1447                  * in the page tables. But it might just be unreadable,
1448                  * in which case we just give up and fill the result with
1449                  * zeroes.
1450                  */
1451                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1452                         memset(kaddr, 0, PAGE_SIZE);
1453                 kunmap_atomic(kaddr, KM_USER0);
1454                 return;
1455                 
1456         }
1457         copy_user_highpage(dst, src, va);
1458 }
1459
1460 /*
1461  * This routine handles present pages, when users try to write
1462  * to a shared page. It is done by copying the page to a new address
1463  * and decrementing the shared-page counter for the old page.
1464  *
1465  * Note that this routine assumes that the protection checks have been
1466  * done by the caller (the low-level page fault routine in most cases).
1467  * Thus we can safely just mark it writable once we've done any necessary
1468  * COW.
1469  *
1470  * We also mark the page dirty at this point even though the page will
1471  * change only once the write actually happens. This avoids a few races,
1472  * and potentially makes it more efficient.
1473  *
1474  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1475  * but allow concurrent faults), with pte both mapped and locked.
1476  * We return with mmap_sem still held, but pte unmapped and unlocked.
1477  */
1478 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1479                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1480                 spinlock_t *ptl, pte_t orig_pte)
1481 {
1482         struct page *old_page, *new_page;
1483         pte_t entry;
1484         int reuse = 0, ret = VM_FAULT_MINOR;
1485         struct page *dirty_page = NULL;
1486
1487         old_page = vm_normal_page(vma, address, orig_pte);
1488         if (!old_page)
1489                 goto gotten;
1490
1491         /*
1492          * Take out anonymous pages first, anonymous shared vmas are
1493          * not dirty accountable.
1494          */
1495         if (PageAnon(old_page)) {
1496                 if (!TestSetPageLocked(old_page)) {
1497                         reuse = can_share_swap_page(old_page);
1498                         unlock_page(old_page);
1499                 }
1500         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1501                                         (VM_WRITE|VM_SHARED))) {
1502                 /*
1503                  * Only catch write-faults on shared writable pages,
1504                  * read-only shared pages can get COWed by
1505                  * get_user_pages(.write=1, .force=1).
1506                  */
1507                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1508                         /*
1509                          * Notify the address space that the page is about to
1510                          * become writable so that it can prohibit this or wait
1511                          * for the page to get into an appropriate state.
1512                          *
1513                          * We do this without the lock held, so that it can
1514                          * sleep if it needs to.
1515                          */
1516                         page_cache_get(old_page);
1517                         pte_unmap_unlock(page_table, ptl);
1518
1519                         if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
1520                                 goto unwritable_page;
1521
1522                         page_cache_release(old_page);
1523
1524                         /*
1525                          * Since we dropped the lock we need to revalidate
1526                          * the PTE as someone else may have changed it.  If
1527                          * they did, we just return, as we can count on the
1528                          * MMU to tell us if they didn't also make it writable.
1529                          */
1530                         page_table = pte_offset_map_lock(mm, pmd, address,
1531                                                          &ptl);
1532                         if (!pte_same(*page_table, orig_pte))
1533                                 goto unlock;
1534                 }
1535                 dirty_page = old_page;
1536                 get_page(dirty_page);
1537                 reuse = 1;
1538         }
1539
1540         if (reuse) {
1541                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1542                 entry = pte_mkyoung(orig_pte);
1543                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1544                 ptep_set_access_flags(vma, address, page_table, entry, 1);
1545                 update_mmu_cache(vma, address, entry);
1546                 lazy_mmu_prot_update(entry);
1547                 ret |= VM_FAULT_WRITE;
1548                 goto unlock;
1549         }
1550
1551         /*
1552          * Ok, we need to copy. Oh, well..
1553          */
1554         page_cache_get(old_page);
1555 gotten:
1556         pte_unmap_unlock(page_table, ptl);
1557
1558         if (unlikely(anon_vma_prepare(vma)))
1559                 goto oom;
1560         if (old_page == ZERO_PAGE(address)) {
1561                 new_page = alloc_zeroed_user_highpage(vma, address);
1562                 if (!new_page)
1563                         goto oom;
1564         } else {
1565                 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1566                 if (!new_page)
1567                         goto oom;
1568                 cow_user_page(new_page, old_page, address);
1569         }
1570
1571         /*
1572          * Re-check the pte - we dropped the lock
1573          */
1574         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1575         if (likely(pte_same(*page_table, orig_pte))) {
1576                 if (old_page) {
1577                         page_remove_rmap(old_page);
1578                         if (!PageAnon(old_page)) {
1579                                 dec_mm_counter(mm, file_rss);
1580                                 inc_mm_counter(mm, anon_rss);
1581                         }
1582                 } else
1583                         inc_mm_counter(mm, anon_rss);
1584                 flush_cache_page(vma, address, pte_pfn(orig_pte));
1585                 entry = mk_pte(new_page, vma->vm_page_prot);
1586                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1587                 lazy_mmu_prot_update(entry);
1588                 /*
1589                  * Clear the pte entry and flush it first, before updating the
1590                  * pte with the new entry. This will avoid a race condition
1591                  * seen in the presence of one thread doing SMC and another
1592                  * thread doing COW.
1593                  */
1594                 ptep_clear_flush(vma, address, page_table);
1595                 set_pte_at(mm, address, page_table, entry);
1596                 update_mmu_cache(vma, address, entry);
1597                 lru_cache_add_active(new_page);
1598                 page_add_new_anon_rmap(new_page, vma, address);
1599
1600                 /* Free the old page.. */
1601                 new_page = old_page;
1602                 ret |= VM_FAULT_WRITE;
1603         }
1604         if (new_page)
1605                 page_cache_release(new_page);
1606         if (old_page)
1607                 page_cache_release(old_page);
1608 unlock:
1609         pte_unmap_unlock(page_table, ptl);
1610         if (dirty_page) {
1611                 set_page_dirty_balance(dirty_page);
1612                 put_page(dirty_page);
1613         }
1614         return ret;
1615 oom:
1616         if (old_page)
1617                 page_cache_release(old_page);
1618         return VM_FAULT_OOM;
1619
1620 unwritable_page:
1621         page_cache_release(old_page);
1622         return VM_FAULT_SIGBUS;
1623 }
1624
1625 /*
1626  * Helper functions for unmap_mapping_range().
1627  *
1628  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1629  *
1630  * We have to restart searching the prio_tree whenever we drop the lock,
1631  * since the iterator is only valid while the lock is held, and anyway
1632  * a later vma might be split and reinserted earlier while lock dropped.
1633  *
1634  * The list of nonlinear vmas could be handled more efficiently, using
1635  * a placeholder, but handle it in the same way until a need is shown.
1636  * It is important to search the prio_tree before nonlinear list: a vma
1637  * may become nonlinear and be shifted from prio_tree to nonlinear list
1638  * while the lock is dropped; but never shifted from list to prio_tree.
1639  *
1640  * In order to make forward progress despite restarting the search,
1641  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1642  * quickly skip it next time around.  Since the prio_tree search only
1643  * shows us those vmas affected by unmapping the range in question, we
1644  * can't efficiently keep all vmas in step with mapping->truncate_count:
1645  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1646  * mapping->truncate_count and vma->vm_truncate_count are protected by
1647  * i_mmap_lock.
1648  *
1649  * In order to make forward progress despite repeatedly restarting some
1650  * large vma, note the restart_addr from unmap_vmas when it breaks out:
1651  * and restart from that address when we reach that vma again.  It might
1652  * have been split or merged, shrunk or extended, but never shifted: so
1653  * restart_addr remains valid so long as it remains in the vma's range.
1654  * unmap_mapping_range forces truncate_count to leap over page-aligned
1655  * values so we can save vma's restart_addr in its truncate_count field.
1656  */
1657 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1658
1659 static void reset_vma_truncate_counts(struct address_space *mapping)
1660 {
1661         struct vm_area_struct *vma;
1662         struct prio_tree_iter iter;
1663
1664         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1665                 vma->vm_truncate_count = 0;
1666         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1667                 vma->vm_truncate_count = 0;
1668 }
1669
1670 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1671                 unsigned long start_addr, unsigned long end_addr,
1672                 struct zap_details *details)
1673 {
1674         unsigned long restart_addr;
1675         int need_break;
1676
1677 again:
1678         restart_addr = vma->vm_truncate_count;
1679         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1680                 start_addr = restart_addr;
1681                 if (start_addr >= end_addr) {
1682                         /* Top of vma has been split off since last time */
1683                         vma->vm_truncate_count = details->truncate_count;
1684                         return 0;
1685                 }
1686         }
1687
1688         restart_addr = zap_page_range(vma, start_addr,
1689                                         end_addr - start_addr, details);
1690         need_break = need_resched() ||
1691                         need_lockbreak(details->i_mmap_lock);
1692
1693         if (restart_addr >= end_addr) {
1694                 /* We have now completed this vma: mark it so */
1695                 vma->vm_truncate_count = details->truncate_count;
1696                 if (!need_break)
1697                         return 0;
1698         } else {
1699                 /* Note restart_addr in vma's truncate_count field */
1700                 vma->vm_truncate_count = restart_addr;
1701                 if (!need_break)
1702                         goto again;
1703         }
1704
1705         spin_unlock(details->i_mmap_lock);
1706         cond_resched();
1707         spin_lock(details->i_mmap_lock);
1708         return -EINTR;
1709 }
1710
1711 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1712                                             struct zap_details *details)
1713 {
1714         struct vm_area_struct *vma;
1715         struct prio_tree_iter iter;
1716         pgoff_t vba, vea, zba, zea;
1717
1718 restart:
1719         vma_prio_tree_foreach(vma, &iter, root,
1720                         details->first_index, details->last_index) {
1721                 /* Skip quickly over those we have already dealt with */
1722                 if (vma->vm_truncate_count == details->truncate_count)
1723                         continue;
1724
1725                 vba = vma->vm_pgoff;
1726                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1727                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1728                 zba = details->first_index;
1729                 if (zba < vba)
1730                         zba = vba;
1731                 zea = details->last_index;
1732                 if (zea > vea)
1733                         zea = vea;
1734
1735                 if (unmap_mapping_range_vma(vma,
1736                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1737                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1738                                 details) < 0)
1739                         goto restart;
1740         }
1741 }
1742
1743 static inline void unmap_mapping_range_list(struct list_head *head,
1744                                             struct zap_details *details)
1745 {
1746         struct vm_area_struct *vma;
1747
1748         /*
1749          * In nonlinear VMAs there is no correspondence between virtual address
1750          * offset and file offset.  So we must perform an exhaustive search
1751          * across *all* the pages in each nonlinear VMA, not just the pages
1752          * whose virtual address lies outside the file truncation point.
1753          */
1754 restart:
1755         list_for_each_entry(vma, head, shared.vm_set.list) {
1756                 /* Skip quickly over those we have already dealt with */
1757                 if (vma->vm_truncate_count == details->truncate_count)
1758                         continue;
1759                 details->nonlinear_vma = vma;
1760                 if (unmap_mapping_range_vma(vma, vma->vm_start,
1761                                         vma->vm_end, details) < 0)
1762                         goto restart;
1763         }
1764 }
1765
1766 /**
1767  * unmap_mapping_range - unmap the portion of all mmaps
1768  * in the specified address_space corresponding to the specified
1769  * page range in the underlying file.
1770  * @mapping: the address space containing mmaps to be unmapped.
1771  * @holebegin: byte in first page to unmap, relative to the start of
1772  * the underlying file.  This will be rounded down to a PAGE_SIZE
1773  * boundary.  Note that this is different from vmtruncate(), which
1774  * must keep the partial page.  In contrast, we must get rid of
1775  * partial pages.
1776  * @holelen: size of prospective hole in bytes.  This will be rounded
1777  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1778  * end of the file.
1779  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1780  * but 0 when invalidating pagecache, don't throw away private data.
1781  */
1782 void unmap_mapping_range(struct address_space *mapping,
1783                 loff_t const holebegin, loff_t const holelen, int even_cows)
1784 {
1785         struct zap_details details;
1786         pgoff_t hba = holebegin >> PAGE_SHIFT;
1787         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1788
1789         /* Check for overflow. */
1790         if (sizeof(holelen) > sizeof(hlen)) {
1791                 long long holeend =
1792                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1793                 if (holeend & ~(long long)ULONG_MAX)
1794                         hlen = ULONG_MAX - hba + 1;
1795         }
1796
1797         details.check_mapping = even_cows? NULL: mapping;
1798         details.nonlinear_vma = NULL;
1799         details.first_index = hba;
1800         details.last_index = hba + hlen - 1;
1801         if (details.last_index < details.first_index)
1802                 details.last_index = ULONG_MAX;
1803         details.i_mmap_lock = &mapping->i_mmap_lock;
1804
1805         spin_lock(&mapping->i_mmap_lock);
1806
1807         /* serialize i_size write against truncate_count write */
1808         smp_wmb();
1809         /* Protect against page faults, and endless unmapping loops */
1810         mapping->truncate_count++;
1811         /*
1812          * For archs where spin_lock has inclusive semantics like ia64
1813          * this smp_mb() will prevent to read pagetable contents
1814          * before the truncate_count increment is visible to
1815          * other cpus.
1816          */
1817         smp_mb();
1818         if (unlikely(is_restart_addr(mapping->truncate_count))) {
1819                 if (mapping->truncate_count == 0)
1820                         reset_vma_truncate_counts(mapping);
1821                 mapping->truncate_count++;
1822         }
1823         details.truncate_count = mapping->truncate_count;
1824
1825         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1826                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1827         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1828                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1829         spin_unlock(&mapping->i_mmap_lock);
1830 }
1831 EXPORT_SYMBOL(unmap_mapping_range);
1832
1833 /**
1834  * vmtruncate - unmap mappings "freed" by truncate() syscall
1835  * @inode: inode of the file used
1836  * @offset: file offset to start truncating
1837  *
1838  * NOTE! We have to be ready to update the memory sharing
1839  * between the file and the memory map for a potential last
1840  * incomplete page.  Ugly, but necessary.
1841  */
1842 int vmtruncate(struct inode * inode, loff_t offset)
1843 {
1844         struct address_space *mapping = inode->i_mapping;
1845         unsigned long limit;
1846
1847         if (inode->i_size < offset)
1848                 goto do_expand;
1849         /*
1850          * truncation of in-use swapfiles is disallowed - it would cause
1851          * subsequent swapout to scribble on the now-freed blocks.
1852          */
1853         if (IS_SWAPFILE(inode))
1854                 goto out_busy;
1855         i_size_write(inode, offset);
1856         unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1857         truncate_inode_pages(mapping, offset);
1858         goto out_truncate;
1859
1860 do_expand:
1861         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1862         if (limit != RLIM_INFINITY && offset > limit)
1863                 goto out_sig;
1864         if (offset > inode->i_sb->s_maxbytes)
1865                 goto out_big;
1866         i_size_write(inode, offset);
1867
1868 out_truncate:
1869         if (inode->i_op && inode->i_op->truncate)
1870                 inode->i_op->truncate(inode);
1871         return 0;
1872 out_sig:
1873         send_sig(SIGXFSZ, current, 0);
1874 out_big:
1875         return -EFBIG;
1876 out_busy:
1877         return -ETXTBSY;
1878 }
1879 EXPORT_SYMBOL(vmtruncate);
1880
1881 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1882 {
1883         struct address_space *mapping = inode->i_mapping;
1884
1885         /*
1886          * If the underlying filesystem is not going to provide
1887          * a way to truncate a range of blocks (punch a hole) -
1888          * we should return failure right now.
1889          */
1890         if (!inode->i_op || !inode->i_op->truncate_range)
1891                 return -ENOSYS;
1892
1893         mutex_lock(&inode->i_mutex);
1894         down_write(&inode->i_alloc_sem);
1895         unmap_mapping_range(mapping, offset, (end - offset), 1);
1896         truncate_inode_pages_range(mapping, offset, end);
1897         inode->i_op->truncate_range(inode, offset, end);
1898         up_write(&inode->i_alloc_sem);
1899         mutex_unlock(&inode->i_mutex);
1900
1901         return 0;
1902 }
1903 EXPORT_UNUSED_SYMBOL(vmtruncate_range);  /*  June 2006  */
1904
1905 /**
1906  * swapin_readahead - swap in pages in hope we need them soon
1907  * @entry: swap entry of this memory
1908  * @addr: address to start
1909  * @vma: user vma this addresses belong to
1910  *
1911  * Primitive swap readahead code. We simply read an aligned block of
1912  * (1 << page_cluster) entries in the swap area. This method is chosen
1913  * because it doesn't cost us any seek time.  We also make sure to queue
1914  * the 'original' request together with the readahead ones...
1915  *
1916  * This has been extended to use the NUMA policies from the mm triggering
1917  * the readahead.
1918  *
1919  * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1920  */
1921 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1922 {
1923 #ifdef CONFIG_NUMA
1924         struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1925 #endif
1926         int i, num;
1927         struct page *new_page;
1928         unsigned long offset;
1929
1930         /*
1931          * Get the number of handles we should do readahead io to.
1932          */
1933         num = valid_swaphandles(entry, &offset);
1934         for (i = 0; i < num; offset++, i++) {
1935                 /* Ok, do the async read-ahead now */
1936                 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1937                                                            offset), vma, addr);
1938                 if (!new_page)
1939                         break;
1940                 page_cache_release(new_page);
1941 #ifdef CONFIG_NUMA
1942                 /*
1943                  * Find the next applicable VMA for the NUMA policy.
1944                  */
1945                 addr += PAGE_SIZE;
1946                 if (addr == 0)
1947                         vma = NULL;
1948                 if (vma) {
1949                         if (addr >= vma->vm_end) {
1950                                 vma = next_vma;
1951                                 next_vma = vma ? vma->vm_next : NULL;
1952                         }
1953                         if (vma && addr < vma->vm_start)
1954                                 vma = NULL;
1955                 } else {
1956                         if (next_vma && addr >= next_vma->vm_start) {
1957                                 vma = next_vma;
1958                                 next_vma = vma->vm_next;
1959                         }
1960                 }
1961 #endif
1962         }
1963         lru_add_drain();        /* Push any new pages onto the LRU now */
1964 }
1965
1966 /*
1967  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1968  * but allow concurrent faults), and pte mapped but not yet locked.
1969  * We return with mmap_sem still held, but pte unmapped and unlocked.
1970  */
1971 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
1972                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1973                 int write_access, pte_t orig_pte)
1974 {
1975         spinlock_t *ptl;
1976         struct page *page;
1977         swp_entry_t entry;
1978         pte_t pte;
1979         int ret = VM_FAULT_MINOR;
1980
1981         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1982                 goto out;
1983
1984         entry = pte_to_swp_entry(orig_pte);
1985         if (is_migration_entry(entry)) {
1986                 migration_entry_wait(mm, pmd, address);
1987                 goto out;
1988         }
1989         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
1990         page = lookup_swap_cache(entry);
1991         if (!page) {
1992                 swapin_readahead(entry, address, vma);
1993                 page = read_swap_cache_async(entry, vma, address);
1994                 if (!page) {
1995                         /*
1996                          * Back out if somebody else faulted in this pte
1997                          * while we released the pte lock.
1998                          */
1999                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2000                         if (likely(pte_same(*page_table, orig_pte)))
2001                                 ret = VM_FAULT_OOM;
2002                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2003                         goto unlock;
2004                 }
2005
2006                 /* Had to read the page from swap area: Major fault */
2007                 ret = VM_FAULT_MAJOR;
2008                 count_vm_event(PGMAJFAULT);
2009                 grab_swap_token();
2010         }
2011
2012         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2013         mark_page_accessed(page);
2014         lock_page(page);
2015
2016         /*
2017          * Back out if somebody else already faulted in this pte.
2018          */
2019         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2020         if (unlikely(!pte_same(*page_table, orig_pte)))
2021                 goto out_nomap;
2022
2023         if (unlikely(!PageUptodate(page))) {
2024                 ret = VM_FAULT_SIGBUS;
2025                 goto out_nomap;
2026         }
2027
2028         /* The page isn't present yet, go ahead with the fault. */
2029
2030         inc_mm_counter(mm, anon_rss);
2031         pte = mk_pte(page, vma->vm_page_prot);
2032         if (write_access && can_share_swap_page(page)) {
2033                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2034                 write_access = 0;
2035         }
2036
2037         flush_icache_page(vma, page);
2038         set_pte_at(mm, address, page_table, pte);
2039         page_add_anon_rmap(page, vma, address);
2040
2041         swap_free(entry);
2042         if (vm_swap_full())
2043                 remove_exclusive_swap_page(page);
2044         unlock_page(page);
2045
2046         if (write_access) {
2047                 if (do_wp_page(mm, vma, address,
2048                                 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
2049                         ret = VM_FAULT_OOM;
2050                 goto out;
2051         }
2052
2053         /* No need to invalidate - it was non-present before */
2054         update_mmu_cache(vma, address, pte);
2055         lazy_mmu_prot_update(pte);
2056 unlock:
2057         pte_unmap_unlock(page_table, ptl);
2058 out:
2059         return ret;
2060 out_nomap:
2061         pte_unmap_unlock(page_table, ptl);
2062         unlock_page(page);
2063         page_cache_release(page);
2064         return ret;
2065 }
2066
2067 /*
2068  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2069  * but allow concurrent faults), and pte mapped but not yet locked.
2070  * We return with mmap_sem still held, but pte unmapped and unlocked.
2071  */
2072 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2073                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2074                 int write_access)
2075 {
2076         struct page *page;
2077         spinlock_t *ptl;
2078         pte_t entry;
2079
2080         if (write_access) {
2081                 /* Allocate our own private page. */
2082                 pte_unmap(page_table);
2083
2084                 if (unlikely(anon_vma_prepare(vma)))
2085                         goto oom;
2086                 page = alloc_zeroed_user_highpage(vma, address);
2087                 if (!page)
2088                         goto oom;
2089
2090                 entry = mk_pte(page, vma->vm_page_prot);
2091                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2092
2093                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2094                 if (!pte_none(*page_table))
2095                         goto release;
2096                 inc_mm_counter(mm, anon_rss);
2097                 lru_cache_add_active(page);
2098                 page_add_new_anon_rmap(page, vma, address);
2099         } else {
2100                 /* Map the ZERO_PAGE - vm_page_prot is readonly */
2101                 page = ZERO_PAGE(address);
2102                 page_cache_get(page);
2103                 entry = mk_pte(page, vma->vm_page_prot);
2104
2105                 ptl = pte_lockptr(mm, pmd);
2106                 spin_lock(ptl);
2107                 if (!pte_none(*page_table))
2108                         goto release;
2109                 inc_mm_counter(mm, file_rss);
2110                 page_add_file_rmap(page);
2111         }
2112
2113         set_pte_at(mm, address, page_table, entry);
2114
2115         /* No need to invalidate - it was non-present before */
2116         update_mmu_cache(vma, address, entry);
2117         lazy_mmu_prot_update(entry);
2118 unlock:
2119         pte_unmap_unlock(page_table, ptl);
2120         return VM_FAULT_MINOR;
2121 release:
2122         page_cache_release(page);
2123         goto unlock;
2124 oom:
2125         return VM_FAULT_OOM;
2126 }
2127
2128 /*
2129  * do_no_page() tries to create a new page mapping. It aggressively
2130  * tries to share with existing pages, but makes a separate copy if
2131  * the "write_access" parameter is true in order to avoid the next
2132  * page fault.
2133  *
2134  * As this is called only for pages that do not currently exist, we
2135  * do not need to flush old virtual caches or the TLB.
2136  *
2137  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2138  * but allow concurrent faults), and pte mapped but not yet locked.
2139  * We return with mmap_sem still held, but pte unmapped and unlocked.
2140  */
2141 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2142                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2143                 int write_access)
2144 {
2145         spinlock_t *ptl;
2146         struct page *new_page;
2147         struct address_space *mapping = NULL;
2148         pte_t entry;
2149         unsigned int sequence = 0;
2150         int ret = VM_FAULT_MINOR;
2151         int anon = 0;
2152         struct page *dirty_page = NULL;
2153
2154         pte_unmap(page_table);
2155         BUG_ON(vma->vm_flags & VM_PFNMAP);
2156
2157         if (vma->vm_file) {
2158                 mapping = vma->vm_file->f_mapping;
2159                 sequence = mapping->truncate_count;
2160                 smp_rmb(); /* serializes i_size against truncate_count */
2161         }
2162 retry:
2163         new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2164         /*
2165          * No smp_rmb is needed here as long as there's a full
2166          * spin_lock/unlock sequence inside the ->nopage callback
2167          * (for the pagecache lookup) that acts as an implicit
2168          * smp_mb() and prevents the i_size read to happen
2169          * after the next truncate_count read.
2170          */
2171
2172         /* no page was available -- either SIGBUS or OOM */
2173         if (new_page == NOPAGE_SIGBUS)
2174                 return VM_FAULT_SIGBUS;
2175         if (new_page == NOPAGE_OOM)
2176                 return VM_FAULT_OOM;
2177
2178         /*
2179          * Should we do an early C-O-W break?
2180          */
2181         if (write_access) {
2182                 if (!(vma->vm_flags & VM_SHARED)) {
2183                         struct page *page;
2184
2185                         if (unlikely(anon_vma_prepare(vma)))
2186                                 goto oom;
2187                         page = alloc_page_vma(GFP_HIGHUSER, vma, address);
2188                         if (!page)
2189                                 goto oom;
2190                         copy_user_highpage(page, new_page, address);
2191                         page_cache_release(new_page);
2192                         new_page = page;
2193                         anon = 1;
2194
2195                 } else {
2196                         /* if the page will be shareable, see if the backing
2197                          * address space wants to know that the page is about
2198                          * to become writable */
2199                         if (vma->vm_ops->page_mkwrite &&
2200                             vma->vm_ops->page_mkwrite(vma, new_page) < 0
2201                             ) {
2202                                 page_cache_release(new_page);
2203                                 return VM_FAULT_SIGBUS;
2204                         }
2205                 }
2206         }
2207
2208         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2209         /*
2210          * For a file-backed vma, someone could have truncated or otherwise
2211          * invalidated this page.  If unmap_mapping_range got called,
2212          * retry getting the page.
2213          */
2214         if (mapping && unlikely(sequence != mapping->truncate_count)) {
2215                 pte_unmap_unlock(page_table, ptl);
2216                 page_cache_release(new_page);
2217                 cond_resched();
2218                 sequence = mapping->truncate_count;
2219                 smp_rmb();
2220                 goto retry;
2221         }
2222
2223         /*
2224          * This silly early PAGE_DIRTY setting removes a race
2225          * due to the bad i386 page protection. But it's valid
2226          * for other architectures too.
2227          *
2228          * Note that if write_access is true, we either now have
2229          * an exclusive copy of the page, or this is a shared mapping,
2230          * so we can make it writable and dirty to avoid having to
2231          * handle that later.
2232          */
2233         /* Only go through if we didn't race with anybody else... */
2234         if (pte_none(*page_table)) {
2235                 flush_icache_page(vma, new_page);
2236                 entry = mk_pte(new_page, vma->vm_page_prot);
2237                 if (write_access)
2238                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2239                 set_pte_at(mm, address, page_table, entry);
2240                 if (anon) {
2241                         inc_mm_counter(mm, anon_rss);
2242                         lru_cache_add_active(new_page);
2243                         page_add_new_anon_rmap(new_page, vma, address);
2244                 } else {
2245                         inc_mm_counter(mm, file_rss);
2246                         page_add_file_rmap(new_page);
2247                         if (write_access) {
2248                                 dirty_page = new_page;
2249                                 get_page(dirty_page);
2250                         }
2251                 }
2252         } else {
2253                 /* One of our sibling threads was faster, back out. */
2254                 page_cache_release(new_page);
2255                 goto unlock;
2256         }
2257
2258         /* no need to invalidate: a not-present page shouldn't be cached */
2259         update_mmu_cache(vma, address, entry);
2260         lazy_mmu_prot_update(entry);
2261 unlock:
2262         pte_unmap_unlock(page_table, ptl);
2263         if (dirty_page) {
2264                 set_page_dirty_balance(dirty_page);
2265                 put_page(dirty_page);
2266         }
2267         return ret;
2268 oom:
2269         page_cache_release(new_page);
2270         return VM_FAULT_OOM;
2271 }
2272
2273 /*
2274  * do_no_pfn() tries to create a new page mapping for a page without
2275  * a struct_page backing it
2276  *
2277  * As this is called only for pages that do not currently exist, we
2278  * do not need to flush old virtual caches or the TLB.
2279  *
2280  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2281  * but allow concurrent faults), and pte mapped but not yet locked.
2282  * We return with mmap_sem still held, but pte unmapped and unlocked.
2283  *
2284  * It is expected that the ->nopfn handler always returns the same pfn
2285  * for a given virtual mapping.
2286  *
2287  * Mark this `noinline' to prevent it from bloating the main pagefault code.
2288  */
2289 static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
2290                      unsigned long address, pte_t *page_table, pmd_t *pmd,
2291                      int write_access)
2292 {
2293         spinlock_t *ptl;
2294         pte_t entry;
2295         unsigned long pfn;
2296         int ret = VM_FAULT_MINOR;
2297
2298         pte_unmap(page_table);
2299         BUG_ON(!(vma->vm_flags & VM_PFNMAP));
2300         BUG_ON(is_cow_mapping(vma->vm_flags));
2301
2302         pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2303         if (pfn == NOPFN_OOM)
2304                 return VM_FAULT_OOM;
2305         if (pfn == NOPFN_SIGBUS)
2306                 return VM_FAULT_SIGBUS;
2307
2308         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2309
2310         /* Only go through if we didn't race with anybody else... */
2311         if (pte_none(*page_table)) {
2312                 entry = pfn_pte(pfn, vma->vm_page_prot);
2313                 if (write_access)
2314                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2315                 set_pte_at(mm, address, page_table, entry);
2316         }
2317         pte_unmap_unlock(page_table, ptl);
2318         return ret;
2319 }
2320
2321 /*
2322  * Fault of a previously existing named mapping. Repopulate the pte
2323  * from the encoded file_pte if possible. This enables swappable
2324  * nonlinear vmas.
2325  *
2326  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2327  * but allow concurrent faults), and pte mapped but not yet locked.
2328  * We return with mmap_sem still held, but pte unmapped and unlocked.
2329  */
2330 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
2331                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2332                 int write_access, pte_t orig_pte)
2333 {
2334         pgoff_t pgoff;
2335         int err;
2336
2337         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2338                 return VM_FAULT_MINOR;
2339
2340         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2341                 /*
2342                  * Page table corrupted: show pte and kill process.
2343                  */
2344                 print_bad_pte(vma, orig_pte, address);
2345                 return VM_FAULT_OOM;
2346         }
2347         /* We can then assume vm->vm_ops && vma->vm_ops->populate */
2348
2349         pgoff = pte_to_pgoff(orig_pte);
2350         err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
2351                                         vma->vm_page_prot, pgoff, 0);
2352         if (err == -ENOMEM)
2353                 return VM_FAULT_OOM;
2354         if (err)
2355                 return VM_FAULT_SIGBUS;
2356         return VM_FAULT_MAJOR;
2357 }
2358
2359 /*
2360  * These routines also need to handle stuff like marking pages dirty
2361  * and/or accessed for architectures that don't do it in hardware (most
2362  * RISC architectures).  The early dirtying is also good on the i386.
2363  *
2364  * There is also a hook called "update_mmu_cache()" that architectures
2365  * with external mmu caches can use to update those (ie the Sparc or
2366  * PowerPC hashed page tables that act as extended TLBs).
2367  *
2368  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2369  * but allow concurrent faults), and pte mapped but not yet locked.
2370  * We return with mmap_sem still held, but pte unmapped and unlocked.
2371  */
2372 static inline int handle_pte_fault(struct mm_struct *mm,
2373                 struct vm_area_struct *vma, unsigned long address,
2374                 pte_t *pte, pmd_t *pmd, int write_access)
2375 {
2376         pte_t entry;
2377         pte_t old_entry;
2378         spinlock_t *ptl;
2379
2380         old_entry = entry = *pte;
2381         if (!pte_present(entry)) {
2382                 if (pte_none(entry)) {
2383                         if (vma->vm_ops) {
2384                                 if (vma->vm_ops->nopage)
2385                                         return do_no_page(mm, vma, address,
2386                                                           pte, pmd,
2387                                                           write_access);
2388                                 if (unlikely(vma->vm_ops->nopfn))
2389                                         return do_no_pfn(mm, vma, address, pte,
2390                                                          pmd, write_access);
2391                         }
2392                         return do_anonymous_page(mm, vma, address,
2393                                                  pte, pmd, write_access);
2394                 }
2395                 if (pte_file(entry))
2396                         return do_file_page(mm, vma, address,
2397                                         pte, pmd, write_access, entry);
2398                 return do_swap_page(mm, vma, address,
2399                                         pte, pmd, write_access, entry);
2400         }
2401
2402         ptl = pte_lockptr(mm, pmd);
2403         spin_lock(ptl);
2404         if (unlikely(!pte_same(*pte, entry)))
2405                 goto unlock;
2406         if (write_access) {
2407                 if (!pte_write(entry))
2408                         return do_wp_page(mm, vma, address,
2409                                         pte, pmd, ptl, entry);
2410                 entry = pte_mkdirty(entry);
2411         }
2412         entry = pte_mkyoung(entry);
2413         if (!pte_same(old_entry, entry)) {
2414                 ptep_set_access_flags(vma, address, pte, entry, write_access);
2415                 update_mmu_cache(vma, address, entry);
2416                 lazy_mmu_prot_update(entry);
2417         } else {
2418                 /*
2419                  * This is needed only for protection faults but the arch code
2420                  * is not yet telling us if this is a protection fault or not.
2421                  * This still avoids useless tlb flushes for .text page faults
2422                  * with threads.
2423                  */
2424                 if (write_access)
2425                         flush_tlb_page(vma, address);
2426         }
2427 unlock:
2428         pte_unmap_unlock(pte, ptl);
2429         return VM_FAULT_MINOR;
2430 }
2431
2432 /*
2433  * By the time we get here, we already hold the mm semaphore
2434  */
2435 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2436                 unsigned long address, int write_access)
2437 {
2438         pgd_t *pgd;
2439         pud_t *pud;
2440         pmd_t *pmd;
2441         pte_t *pte;
2442
2443         __set_current_state(TASK_RUNNING);
2444
2445         count_vm_event(PGFAULT);
2446
2447         if (unlikely(is_vm_hugetlb_page(vma)))
2448                 return hugetlb_fault(mm, vma, address, write_access);
2449
2450         pgd = pgd_offset(mm, address);
2451         pud = pud_alloc(mm, pgd, address);
2452         if (!pud)
2453                 return VM_FAULT_OOM;
2454         pmd = pmd_alloc(mm, pud, address);
2455         if (!pmd)
2456                 return VM_FAULT_OOM;
2457         pte = pte_alloc_map(mm, pmd, address);
2458         if (!pte)
2459                 return VM_FAULT_OOM;
2460
2461         return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2462 }
2463
2464 EXPORT_SYMBOL_GPL(__handle_mm_fault);
2465
2466 #ifndef __PAGETABLE_PUD_FOLDED
2467 /*
2468  * Allocate page upper directory.
2469  * We've already handled the fast-path in-line.
2470  */
2471 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2472 {
2473         pud_t *new = pud_alloc_one(mm, address);
2474         if (!new)
2475                 return -ENOMEM;
2476
2477         spin_lock(&mm->page_table_lock);
2478         if (pgd_present(*pgd))          /* Another has populated it */
2479                 pud_free(new);
2480         else
2481                 pgd_populate(mm, pgd, new);
2482         spin_unlock(&mm->page_table_lock);
2483         return 0;
2484 }
2485 #else
2486 /* Workaround for gcc 2.96 */
2487 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2488 {
2489         return 0;
2490 }
2491 #endif /* __PAGETABLE_PUD_FOLDED */
2492
2493 #ifndef __PAGETABLE_PMD_FOLDED
2494 /*
2495  * Allocate page middle directory.
2496  * We've already handled the fast-path in-line.
2497  */
2498 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2499 {
2500         pmd_t *new = pmd_alloc_one(mm, address);
2501         if (!new)
2502                 return -ENOMEM;
2503
2504         spin_lock(&mm->page_table_lock);
2505 #ifndef __ARCH_HAS_4LEVEL_HACK
2506         if (pud_present(*pud))          /* Another has populated it */
2507                 pmd_free(new);
2508         else
2509                 pud_populate(mm, pud, new);
2510 #else
2511         if (pgd_present(*pud))          /* Another has populated it */
2512                 pmd_free(new);
2513         else
2514                 pgd_populate(mm, pud, new);
2515 #endif /* __ARCH_HAS_4LEVEL_HACK */
2516         spin_unlock(&mm->page_table_lock);
2517         return 0;
2518 }
2519 #else
2520 /* Workaround for gcc 2.96 */
2521 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2522 {
2523         return 0;
2524 }
2525 #endif /* __PAGETABLE_PMD_FOLDED */
2526
2527 int make_pages_present(unsigned long addr, unsigned long end)
2528 {
2529         int ret, len, write;
2530         struct vm_area_struct * vma;
2531
2532         vma = find_vma(current->mm, addr);
2533         if (!vma)
2534                 return -1;
2535         write = (vma->vm_flags & VM_WRITE) != 0;
2536         BUG_ON(addr >= end);
2537         BUG_ON(end > vma->vm_end);
2538         len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2539         ret = get_user_pages(current, current->mm, addr,
2540                         len, write, 0, NULL, NULL);
2541         if (ret < 0)
2542                 return ret;
2543         return ret == len ? 0 : -1;
2544 }
2545
2546 /* 
2547  * Map a vmalloc()-space virtual address to the physical page.
2548  */
2549 struct page * vmalloc_to_page(void * vmalloc_addr)
2550 {
2551         unsigned long addr = (unsigned long) vmalloc_addr;
2552         struct page *page = NULL;
2553         pgd_t *pgd = pgd_offset_k(addr);
2554         pud_t *pud;
2555         pmd_t *pmd;
2556         pte_t *ptep, pte;
2557   
2558         if (!pgd_none(*pgd)) {
2559                 pud = pud_offset(pgd, addr);
2560                 if (!pud_none(*pud)) {
2561                         pmd = pmd_offset(pud, addr);
2562                         if (!pmd_none(*pmd)) {
2563                                 ptep = pte_offset_map(pmd, addr);
2564                                 pte = *ptep;
2565                                 if (pte_present(pte))
2566                                         page = pte_page(pte);
2567                                 pte_unmap(ptep);
2568                         }
2569                 }
2570         }
2571         return page;
2572 }
2573
2574 EXPORT_SYMBOL(vmalloc_to_page);
2575
2576 /*
2577  * Map a vmalloc()-space virtual address to the physical page frame number.
2578  */
2579 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2580 {
2581         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2582 }
2583
2584 EXPORT_SYMBOL(vmalloc_to_pfn);
2585
2586 #if !defined(__HAVE_ARCH_GATE_AREA)
2587
2588 #if defined(AT_SYSINFO_EHDR)
2589 static struct vm_area_struct gate_vma;
2590
2591 static int __init gate_vma_init(void)
2592 {
2593         gate_vma.vm_mm = NULL;
2594         gate_vma.vm_start = FIXADDR_USER_START;
2595         gate_vma.vm_end = FIXADDR_USER_END;
2596         gate_vma.vm_page_prot = PAGE_READONLY;
2597         gate_vma.vm_flags = 0;
2598         return 0;
2599 }
2600 __initcall(gate_vma_init);
2601 #endif
2602
2603 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2604 {
2605 #ifdef AT_SYSINFO_EHDR
2606         return &gate_vma;
2607 #else
2608         return NULL;
2609 #endif
2610 }
2611
2612 int in_gate_area_no_task(unsigned long addr)
2613 {
2614 #ifdef AT_SYSINFO_EHDR
2615         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2616                 return 1;
2617 #endif
2618         return 0;
2619 }
2620
2621 #endif  /* __HAVE_ARCH_GATE_AREA */
2622
2623 /*
2624  * Access another process' address space.
2625  * Source/target buffer must be kernel space,
2626  * Do not walk the page table directly, use get_user_pages
2627  */
2628 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2629 {
2630         struct mm_struct *mm;
2631         struct vm_area_struct *vma;
2632         struct page *page;
2633         void *old_buf = buf;
2634
2635         mm = get_task_mm(tsk);
2636         if (!mm)
2637                 return 0;
2638
2639         down_read(&mm->mmap_sem);
2640         /* ignore errors, just check how much was sucessfully transfered */
2641         while (len) {
2642                 int bytes, ret, offset;
2643                 void *maddr;
2644
2645                 ret = get_user_pages(tsk, mm, addr, 1,
2646                                 write, 1, &page, &vma);
2647                 if (ret <= 0)
2648                         break;
2649
2650                 bytes = len;
2651                 offset = addr & (PAGE_SIZE-1);
2652                 if (bytes > PAGE_SIZE-offset)
2653                         bytes = PAGE_SIZE-offset;
2654
2655                 maddr = kmap(page);
2656                 if (write) {
2657                         copy_to_user_page(vma, page, addr,
2658                                           maddr + offset, buf, bytes);
2659                         set_page_dirty_lock(page);
2660                 } else {
2661                         copy_from_user_page(vma, page, addr,
2662                                             buf, maddr + offset, bytes);
2663                 }
2664                 kunmap(page);
2665                 page_cache_release(page);
2666                 len -= bytes;
2667                 buf += bytes;
2668                 addr += bytes;
2669         }
2670         up_read(&mm->mmap_sem);
2671         mmput(mm);
2672
2673         return buf - old_buf;
2674 }