blob: 36c85e04fa932e2f4ccd6e334f0537a9acc7b162 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@redhat.com>
7 */
8
9#include <linux/slab.h>
Alexey Dobriyan4af3c9c2007-10-16 23:29:23 -070010#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/mm.h>
12#include <linux/shm.h>
13#include <linux/mman.h>
14#include <linux/pagemap.h>
15#include <linux/swap.h>
16#include <linux/syscalls.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080017#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/init.h>
19#include <linux/file.h>
20#include <linux/fs.h>
21#include <linux/personality.h>
22#include <linux/security.h>
23#include <linux/hugetlb.h>
24#include <linux/profile.h>
25#include <linux/module.h>
26#include <linux/mount.h>
27#include <linux/mempolicy.h>
28#include <linux/rmap.h>
29
30#include <asm/uaccess.h>
31#include <asm/cacheflush.h>
32#include <asm/tlb.h>
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +020033#include <asm/mmu_context.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Kirill Korotaev3a459752006-09-07 14:17:04 +040035#ifndef arch_mmap_check
36#define arch_mmap_check(addr, len, flags) (0)
37#endif
38
Martin Schwidefsky08e7d9b2008-02-04 22:29:16 -080039#ifndef arch_rebalance_pgtables
40#define arch_rebalance_pgtables(addr, len) (addr)
41#endif
42
Hugh Dickinse0da3822005-04-19 13:29:15 -070043static void unmap_region(struct mm_struct *mm,
44 struct vm_area_struct *vma, struct vm_area_struct *prev,
45 unsigned long start, unsigned long end);
46
Linus Torvalds1da177e2005-04-16 15:20:36 -070047/*
48 * WARNING: the debugging will use recursive algorithms so never enable this
49 * unless you know what you are doing.
50 */
51#undef DEBUG_MM_RB
52
53/* description of effects of mapping type and prot in current implementation.
54 * this is due to the limited x86 page protection hardware. The expected
55 * behavior is in parens:
56 *
57 * map_type prot
58 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
59 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
60 * w: (no) no w: (no) no w: (yes) yes w: (no) no
61 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
62 *
63 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
64 * w: (no) no w: (no) no w: (copy) copy w: (no) no
65 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
66 *
67 */
68pgprot_t protection_map[16] = {
69 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
70 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
71};
72
Hugh Dickins804af2c2006-07-26 21:39:49 +010073pgprot_t vm_get_page_prot(unsigned long vm_flags)
74{
75 return protection_map[vm_flags &
76 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
77}
78EXPORT_SYMBOL(vm_get_page_prot);
79
Linus Torvalds1da177e2005-04-16 15:20:36 -070080int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
81int sysctl_overcommit_ratio = 50; /* default is 50% */
Christoph Lameterc3d8c142005-09-06 15:16:33 -070082int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070083atomic_t vm_committed_space = ATOMIC_INIT(0);
84
85/*
86 * Check that a process has enough memory to allocate a new virtual
87 * mapping. 0 means there is enough memory for the allocation to
88 * succeed and -ENOMEM implies there is not.
89 *
90 * We currently support three overcommit policies, which are set via the
91 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
92 *
93 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
94 * Additional code 2002 Jul 20 by Robert Love.
95 *
96 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
97 *
98 * Note this is a helper function intended to be used by LSMs which
99 * wish to use this logic.
100 */
Alan Cox34b4e4a2007-08-22 14:01:28 -0700101int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102{
103 unsigned long free, allowed;
104
105 vm_acct_memory(pages);
106
107 /*
108 * Sometimes we want to use more memory than we have
109 */
110 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
111 return 0;
112
113 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
114 unsigned long n;
115
Christoph Lameter347ce432006-06-30 01:55:35 -0700116 free = global_page_state(NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 free += nr_swap_pages;
118
119 /*
120 * Any slabs which are created with the
121 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
122 * which are reclaimable, under pressure. The dentry
123 * cache and most inode caches should fall into this
124 */
Christoph Lameter972d1a72006-09-25 23:31:51 -0700125 free += global_page_state(NR_SLAB_RECLAIMABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
127 /*
128 * Leave the last 3% for root
129 */
130 if (!cap_sys_admin)
131 free -= free / 32;
132
133 if (free > pages)
134 return 0;
135
136 /*
137 * nr_free_pages() is very expensive on large systems,
138 * only call if we're about to fail.
139 */
140 n = nr_free_pages();
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700141
142 /*
143 * Leave reserved pages. The pages are not for anonymous pages.
144 */
145 if (n <= totalreserve_pages)
146 goto error;
147 else
148 n -= totalreserve_pages;
149
150 /*
151 * Leave the last 3% for root
152 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 if (!cap_sys_admin)
154 n -= n / 32;
155 free += n;
156
157 if (free > pages)
158 return 0;
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700159
160 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 }
162
163 allowed = (totalram_pages - hugetlb_total_pages())
164 * sysctl_overcommit_ratio / 100;
165 /*
166 * Leave the last 3% for root
167 */
168 if (!cap_sys_admin)
169 allowed -= allowed / 32;
170 allowed += total_swap_pages;
171
172 /* Don't let a single process grow too big:
173 leave 3% of the size of this process for other processes */
Alan Cox34b4e4a2007-08-22 14:01:28 -0700174 allowed -= mm->total_vm / 32;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
Simon Derr2f60f8d2005-08-04 19:52:03 -0700176 /*
177 * cast `allowed' as a signed long because vm_committed_space
178 * sometimes has a negative value
179 */
180 if (atomic_read(&vm_committed_space) < (long)allowed)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 return 0;
Hideo AOKI6d9f7832006-04-10 22:53:00 -0700182error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 vm_unacct_memory(pages);
184
185 return -ENOMEM;
186}
187
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188/*
189 * Requires inode->i_mapping->i_mmap_lock
190 */
191static void __remove_shared_vm_struct(struct vm_area_struct *vma,
192 struct file *file, struct address_space *mapping)
193{
194 if (vma->vm_flags & VM_DENYWRITE)
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800195 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 if (vma->vm_flags & VM_SHARED)
197 mapping->i_mmap_writable--;
198
199 flush_dcache_mmap_lock(mapping);
200 if (unlikely(vma->vm_flags & VM_NONLINEAR))
201 list_del_init(&vma->shared.vm_set.list);
202 else
203 vma_prio_tree_remove(vma, &mapping->i_mmap);
204 flush_dcache_mmap_unlock(mapping);
205}
206
207/*
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700208 * Unlink a file-based vm structure from its prio_tree, to hide
209 * vma from rmap and vmtruncate before freeing its page tables.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 */
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700211void unlink_file_vma(struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212{
213 struct file *file = vma->vm_file;
214
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 if (file) {
216 struct address_space *mapping = file->f_mapping;
217 spin_lock(&mapping->i_mmap_lock);
218 __remove_shared_vm_struct(vma, file, mapping);
219 spin_unlock(&mapping->i_mmap_lock);
220 }
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700221}
222
223/*
224 * Close a vm structure and free it, returning the next.
225 */
226static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
227{
228 struct vm_area_struct *next = vma->vm_next;
229
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700230 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 if (vma->vm_ops && vma->vm_ops->close)
232 vma->vm_ops->close(vma);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700233 if (vma->vm_file)
234 fput(vma->vm_file);
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700235 mpol_put(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 kmem_cache_free(vm_area_cachep, vma);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -0700237 return next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238}
239
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240asmlinkage unsigned long sys_brk(unsigned long brk)
241{
242 unsigned long rlim, retval;
243 unsigned long newbrk, oldbrk;
244 struct mm_struct *mm = current->mm;
245
246 down_write(&mm->mmap_sem);
247
Jiri Kosina4cc60282008-02-06 22:39:44 +0100248 if (brk < mm->start_brk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 goto out;
Ram Gupta1e624192006-04-10 22:52:57 -0700250
251 /*
252 * Check against rlimit here. If this check is done later after the test
253 * of oldbrk with newbrk then it can escape the test and let the data
254 * segment grow beyond its set limit the in case where the limit is
255 * not page aligned -Ram Gupta
256 */
257 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
Jiri Kosinac1d171a2008-01-30 13:30:40 +0100258 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
259 (mm->end_data - mm->start_data) > rlim)
Ram Gupta1e624192006-04-10 22:52:57 -0700260 goto out;
261
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 newbrk = PAGE_ALIGN(brk);
263 oldbrk = PAGE_ALIGN(mm->brk);
264 if (oldbrk == newbrk)
265 goto set_brk;
266
267 /* Always allow shrinking brk. */
268 if (brk <= mm->brk) {
269 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
270 goto set_brk;
271 goto out;
272 }
273
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 /* Check against existing mmap mappings. */
275 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
276 goto out;
277
278 /* Ok, looks good - let it rip. */
279 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
280 goto out;
281set_brk:
282 mm->brk = brk;
283out:
284 retval = mm->brk;
285 up_write(&mm->mmap_sem);
286 return retval;
287}
288
289#ifdef DEBUG_MM_RB
290static int browse_rb(struct rb_root *root)
291{
292 int i = 0, j;
293 struct rb_node *nd, *pn = NULL;
294 unsigned long prev = 0, pend = 0;
295
296 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
297 struct vm_area_struct *vma;
298 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
299 if (vma->vm_start < prev)
300 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
301 if (vma->vm_start < pend)
302 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
303 if (vma->vm_start > vma->vm_end)
304 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
305 i++;
306 pn = nd;
David Millerd1af65d2007-02-28 20:13:13 -0800307 prev = vma->vm_start;
308 pend = vma->vm_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 }
310 j = 0;
311 for (nd = pn; nd; nd = rb_prev(nd)) {
312 j++;
313 }
314 if (i != j)
315 printk("backwards %d, forwards %d\n", j, i), i = 0;
316 return i;
317}
318
319void validate_mm(struct mm_struct *mm)
320{
321 int bug = 0;
322 int i = 0;
323 struct vm_area_struct *tmp = mm->mmap;
324 while (tmp) {
325 tmp = tmp->vm_next;
326 i++;
327 }
328 if (i != mm->map_count)
329 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
330 i = browse_rb(&mm->mm_rb);
331 if (i != mm->map_count)
332 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200333 BUG_ON(bug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334}
335#else
336#define validate_mm(mm) do { } while (0)
337#endif
338
339static struct vm_area_struct *
340find_vma_prepare(struct mm_struct *mm, unsigned long addr,
341 struct vm_area_struct **pprev, struct rb_node ***rb_link,
342 struct rb_node ** rb_parent)
343{
344 struct vm_area_struct * vma;
345 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
346
347 __rb_link = &mm->mm_rb.rb_node;
348 rb_prev = __rb_parent = NULL;
349 vma = NULL;
350
351 while (*__rb_link) {
352 struct vm_area_struct *vma_tmp;
353
354 __rb_parent = *__rb_link;
355 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
356
357 if (vma_tmp->vm_end > addr) {
358 vma = vma_tmp;
359 if (vma_tmp->vm_start <= addr)
360 return vma;
361 __rb_link = &__rb_parent->rb_left;
362 } else {
363 rb_prev = __rb_parent;
364 __rb_link = &__rb_parent->rb_right;
365 }
366 }
367
368 *pprev = NULL;
369 if (rb_prev)
370 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
371 *rb_link = __rb_link;
372 *rb_parent = __rb_parent;
373 return vma;
374}
375
376static inline void
377__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
378 struct vm_area_struct *prev, struct rb_node *rb_parent)
379{
380 if (prev) {
381 vma->vm_next = prev->vm_next;
382 prev->vm_next = vma;
383 } else {
384 mm->mmap = vma;
385 if (rb_parent)
386 vma->vm_next = rb_entry(rb_parent,
387 struct vm_area_struct, vm_rb);
388 else
389 vma->vm_next = NULL;
390 }
391}
392
393void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
394 struct rb_node **rb_link, struct rb_node *rb_parent)
395{
396 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
397 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
398}
399
400static inline void __vma_link_file(struct vm_area_struct *vma)
401{
402 struct file * file;
403
404 file = vma->vm_file;
405 if (file) {
406 struct address_space *mapping = file->f_mapping;
407
408 if (vma->vm_flags & VM_DENYWRITE)
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800409 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 if (vma->vm_flags & VM_SHARED)
411 mapping->i_mmap_writable++;
412
413 flush_dcache_mmap_lock(mapping);
414 if (unlikely(vma->vm_flags & VM_NONLINEAR))
415 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
416 else
417 vma_prio_tree_insert(vma, &mapping->i_mmap);
418 flush_dcache_mmap_unlock(mapping);
419 }
420}
421
422static void
423__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
424 struct vm_area_struct *prev, struct rb_node **rb_link,
425 struct rb_node *rb_parent)
426{
427 __vma_link_list(mm, vma, prev, rb_parent);
428 __vma_link_rb(mm, vma, rb_link, rb_parent);
429 __anon_vma_link(vma);
430}
431
432static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
433 struct vm_area_struct *prev, struct rb_node **rb_link,
434 struct rb_node *rb_parent)
435{
436 struct address_space *mapping = NULL;
437
438 if (vma->vm_file)
439 mapping = vma->vm_file->f_mapping;
440
441 if (mapping) {
442 spin_lock(&mapping->i_mmap_lock);
443 vma->vm_truncate_count = mapping->truncate_count;
444 }
445 anon_vma_lock(vma);
446
447 __vma_link(mm, vma, prev, rb_link, rb_parent);
448 __vma_link_file(vma);
449
450 anon_vma_unlock(vma);
451 if (mapping)
452 spin_unlock(&mapping->i_mmap_lock);
453
454 mm->map_count++;
455 validate_mm(mm);
456}
457
458/*
459 * Helper for vma_adjust in the split_vma insert case:
460 * insert vm structure into list and rbtree and anon_vma,
461 * but it has already been inserted into prio_tree earlier.
462 */
463static void
464__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
465{
466 struct vm_area_struct * __vma, * prev;
467 struct rb_node ** rb_link, * rb_parent;
468
469 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200470 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 __vma_link(mm, vma, prev, rb_link, rb_parent);
472 mm->map_count++;
473}
474
475static inline void
476__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
477 struct vm_area_struct *prev)
478{
479 prev->vm_next = vma->vm_next;
480 rb_erase(&vma->vm_rb, &mm->mm_rb);
481 if (mm->mmap_cache == vma)
482 mm->mmap_cache = prev;
483}
484
485/*
486 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
487 * is already present in an i_mmap tree without adjusting the tree.
488 * The following helper function should be used when such adjustments
489 * are necessary. The "insert" vma (if any) is to be inserted
490 * before we drop the necessary locks.
491 */
492void vma_adjust(struct vm_area_struct *vma, unsigned long start,
493 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
494{
495 struct mm_struct *mm = vma->vm_mm;
496 struct vm_area_struct *next = vma->vm_next;
497 struct vm_area_struct *importer = NULL;
498 struct address_space *mapping = NULL;
499 struct prio_tree_root *root = NULL;
500 struct file *file = vma->vm_file;
501 struct anon_vma *anon_vma = NULL;
502 long adjust_next = 0;
503 int remove_next = 0;
504
505 if (next && !insert) {
506 if (end >= next->vm_end) {
507 /*
508 * vma expands, overlapping all the next, and
509 * perhaps the one after too (mprotect case 6).
510 */
511again: remove_next = 1 + (end > next->vm_end);
512 end = next->vm_end;
513 anon_vma = next->anon_vma;
514 importer = vma;
515 } else if (end > next->vm_start) {
516 /*
517 * vma expands, overlapping part of the next:
518 * mprotect case 5 shifting the boundary up.
519 */
520 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
521 anon_vma = next->anon_vma;
522 importer = vma;
523 } else if (end < vma->vm_end) {
524 /*
525 * vma shrinks, and !insert tells it's not
526 * split_vma inserting another: so it must be
527 * mprotect case 4 shifting the boundary down.
528 */
529 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
530 anon_vma = next->anon_vma;
531 importer = next;
532 }
533 }
534
535 if (file) {
536 mapping = file->f_mapping;
537 if (!(vma->vm_flags & VM_NONLINEAR))
538 root = &mapping->i_mmap;
539 spin_lock(&mapping->i_mmap_lock);
540 if (importer &&
541 vma->vm_truncate_count != next->vm_truncate_count) {
542 /*
543 * unmap_mapping_range might be in progress:
544 * ensure that the expanding vma is rescanned.
545 */
546 importer->vm_truncate_count = 0;
547 }
548 if (insert) {
549 insert->vm_truncate_count = vma->vm_truncate_count;
550 /*
551 * Put into prio_tree now, so instantiated pages
552 * are visible to arm/parisc __flush_dcache_page
553 * throughout; but we cannot insert into address
554 * space until vma start or end is updated.
555 */
556 __vma_link_file(insert);
557 }
558 }
559
560 /*
561 * When changing only vma->vm_end, we don't really need
562 * anon_vma lock: but is that case worth optimizing out?
563 */
564 if (vma->anon_vma)
565 anon_vma = vma->anon_vma;
566 if (anon_vma) {
567 spin_lock(&anon_vma->lock);
568 /*
569 * Easily overlooked: when mprotect shifts the boundary,
570 * make sure the expanding vma has anon_vma set if the
571 * shrinking vma had, to cover any anon pages imported.
572 */
573 if (importer && !importer->anon_vma) {
574 importer->anon_vma = anon_vma;
575 __anon_vma_link(importer);
576 }
577 }
578
579 if (root) {
580 flush_dcache_mmap_lock(mapping);
581 vma_prio_tree_remove(vma, root);
582 if (adjust_next)
583 vma_prio_tree_remove(next, root);
584 }
585
586 vma->vm_start = start;
587 vma->vm_end = end;
588 vma->vm_pgoff = pgoff;
589 if (adjust_next) {
590 next->vm_start += adjust_next << PAGE_SHIFT;
591 next->vm_pgoff += adjust_next;
592 }
593
594 if (root) {
595 if (adjust_next)
596 vma_prio_tree_insert(next, root);
597 vma_prio_tree_insert(vma, root);
598 flush_dcache_mmap_unlock(mapping);
599 }
600
601 if (remove_next) {
602 /*
603 * vma_merge has merged next into vma, and needs
604 * us to remove next before dropping the locks.
605 */
606 __vma_unlink(mm, next, vma);
607 if (file)
608 __remove_shared_vm_struct(next, file, mapping);
609 if (next->anon_vma)
610 __anon_vma_merge(vma, next);
611 } else if (insert) {
612 /*
613 * split_vma has split insert from vma, and needs
614 * us to insert it before dropping the locks
615 * (it may either follow vma or precede it).
616 */
617 __insert_vm_struct(mm, insert);
618 }
619
620 if (anon_vma)
621 spin_unlock(&anon_vma->lock);
622 if (mapping)
623 spin_unlock(&mapping->i_mmap_lock);
624
625 if (remove_next) {
626 if (file)
627 fput(file);
628 mm->map_count--;
Lee Schermerhornf0be3d32008-04-28 02:13:08 -0700629 mpol_put(vma_policy(next));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 kmem_cache_free(vm_area_cachep, next);
631 /*
632 * In mprotect's case 6 (see comments on vma_merge),
633 * we must remove another next too. It would clutter
634 * up the code too much to do both in one go.
635 */
636 if (remove_next == 2) {
637 next = vma->vm_next;
638 goto again;
639 }
640 }
641
642 validate_mm(mm);
643}
644
645/*
646 * If the vma has a ->close operation then the driver probably needs to release
647 * per-vma resources, so we don't attempt to merge those.
648 */
Hugh Dickinsa6f563d2006-03-22 00:08:29 -0800649#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650
651static inline int is_mergeable_vma(struct vm_area_struct *vma,
652 struct file *file, unsigned long vm_flags)
653{
654 if (vma->vm_flags != vm_flags)
655 return 0;
656 if (vma->vm_file != file)
657 return 0;
658 if (vma->vm_ops && vma->vm_ops->close)
659 return 0;
660 return 1;
661}
662
663static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
664 struct anon_vma *anon_vma2)
665{
666 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
667}
668
669/*
670 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
671 * in front of (at a lower virtual address and file offset than) the vma.
672 *
673 * We cannot merge two vmas if they have differently assigned (non-NULL)
674 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
675 *
676 * We don't check here for the merged mmap wrapping around the end of pagecache
677 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
678 * wrap, nor mmaps which cover the final page at index -1UL.
679 */
680static int
681can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
682 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
683{
684 if (is_mergeable_vma(vma, file, vm_flags) &&
685 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
686 if (vma->vm_pgoff == vm_pgoff)
687 return 1;
688 }
689 return 0;
690}
691
692/*
693 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
694 * beyond (at a higher virtual address and file offset than) the vma.
695 *
696 * We cannot merge two vmas if they have differently assigned (non-NULL)
697 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
698 */
699static int
700can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
701 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
702{
703 if (is_mergeable_vma(vma, file, vm_flags) &&
704 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
705 pgoff_t vm_pglen;
706 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
707 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
708 return 1;
709 }
710 return 0;
711}
712
713/*
714 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
715 * whether that can be merged with its predecessor or its successor.
716 * Or both (it neatly fills a hole).
717 *
718 * In most cases - when called for mmap, brk or mremap - [addr,end) is
719 * certain not to be mapped by the time vma_merge is called; but when
720 * called for mprotect, it is certain to be already mapped (either at
721 * an offset within prev, or at the start of next), and the flags of
722 * this area are about to be changed to vm_flags - and the no-change
723 * case has already been eliminated.
724 *
725 * The following mprotect cases have to be considered, where AAAA is
726 * the area passed down from mprotect_fixup, never extending beyond one
727 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
728 *
729 * AAAA AAAA AAAA AAAA
730 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
731 * cannot merge might become might become might become
732 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
733 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
734 * mremap move: PPPPNNNNNNNN 8
735 * AAAA
736 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
737 * might become case 1 below case 2 below case 3 below
738 *
739 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
740 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
741 */
742struct vm_area_struct *vma_merge(struct mm_struct *mm,
743 struct vm_area_struct *prev, unsigned long addr,
744 unsigned long end, unsigned long vm_flags,
745 struct anon_vma *anon_vma, struct file *file,
746 pgoff_t pgoff, struct mempolicy *policy)
747{
748 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
749 struct vm_area_struct *area, *next;
750
751 /*
752 * We later require that vma->vm_flags == vm_flags,
753 * so this tests vma->vm_flags & VM_SPECIAL, too.
754 */
755 if (vm_flags & VM_SPECIAL)
756 return NULL;
757
758 if (prev)
759 next = prev->vm_next;
760 else
761 next = mm->mmap;
762 area = next;
763 if (next && next->vm_end == end) /* cases 6, 7, 8 */
764 next = next->vm_next;
765
766 /*
767 * Can it merge with the predecessor?
768 */
769 if (prev && prev->vm_end == addr &&
770 mpol_equal(vma_policy(prev), policy) &&
771 can_vma_merge_after(prev, vm_flags,
772 anon_vma, file, pgoff)) {
773 /*
774 * OK, it can. Can we now merge in the successor as well?
775 */
776 if (next && end == next->vm_start &&
777 mpol_equal(policy, vma_policy(next)) &&
778 can_vma_merge_before(next, vm_flags,
779 anon_vma, file, pgoff+pglen) &&
780 is_mergeable_anon_vma(prev->anon_vma,
781 next->anon_vma)) {
782 /* cases 1, 6 */
783 vma_adjust(prev, prev->vm_start,
784 next->vm_end, prev->vm_pgoff, NULL);
785 } else /* cases 2, 5, 7 */
786 vma_adjust(prev, prev->vm_start,
787 end, prev->vm_pgoff, NULL);
788 return prev;
789 }
790
791 /*
792 * Can this new request be merged in front of next?
793 */
794 if (next && end == next->vm_start &&
795 mpol_equal(policy, vma_policy(next)) &&
796 can_vma_merge_before(next, vm_flags,
797 anon_vma, file, pgoff+pglen)) {
798 if (prev && addr < prev->vm_end) /* case 4 */
799 vma_adjust(prev, prev->vm_start,
800 addr, prev->vm_pgoff, NULL);
801 else /* cases 3, 8 */
802 vma_adjust(area, addr, next->vm_end,
803 next->vm_pgoff - pglen, NULL);
804 return area;
805 }
806
807 return NULL;
808}
809
810/*
811 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
812 * neighbouring vmas for a suitable anon_vma, before it goes off
813 * to allocate a new anon_vma. It checks because a repetitive
814 * sequence of mprotects and faults may otherwise lead to distinct
815 * anon_vmas being allocated, preventing vma merge in subsequent
816 * mprotect.
817 */
818struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
819{
820 struct vm_area_struct *near;
821 unsigned long vm_flags;
822
823 near = vma->vm_next;
824 if (!near)
825 goto try_prev;
826
827 /*
828 * Since only mprotect tries to remerge vmas, match flags
829 * which might be mprotected into each other later on.
830 * Neither mlock nor madvise tries to remerge at present,
831 * so leave their flags as obstructing a merge.
832 */
833 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
834 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
835
836 if (near->anon_vma && vma->vm_end == near->vm_start &&
837 mpol_equal(vma_policy(vma), vma_policy(near)) &&
838 can_vma_merge_before(near, vm_flags,
839 NULL, vma->vm_file, vma->vm_pgoff +
840 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
841 return near->anon_vma;
842try_prev:
843 /*
844 * It is potentially slow to have to call find_vma_prev here.
845 * But it's only on the first write fault on the vma, not
846 * every time, and we could devise a way to avoid it later
847 * (e.g. stash info in next's anon_vma_node when assigning
848 * an anon_vma, or when trying vma_merge). Another time.
849 */
Eric Sesterhenn46a350e2006-04-01 01:23:29 +0200850 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 if (!near)
852 goto none;
853
854 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
855 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
856
857 if (near->anon_vma && near->vm_end == vma->vm_start &&
858 mpol_equal(vma_policy(near), vma_policy(vma)) &&
859 can_vma_merge_after(near, vm_flags,
860 NULL, vma->vm_file, vma->vm_pgoff))
861 return near->anon_vma;
862none:
863 /*
864 * There's no absolute need to look only at touching neighbours:
865 * we could search further afield for "compatible" anon_vmas.
866 * But it would probably just be a waste of time searching,
867 * or lead to too many vmas hanging off the same anon_vma.
868 * We're trying to allow mprotect remerging later on,
869 * not trying to minimize memory used for anon_vmas.
870 */
871 return NULL;
872}
873
874#ifdef CONFIG_PROC_FS
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700875void vm_stat_account(struct mm_struct *mm, unsigned long flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 struct file *file, long pages)
877{
878 const unsigned long stack_flags
879 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
880
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881 if (file) {
882 mm->shared_vm += pages;
883 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
884 mm->exec_vm += pages;
885 } else if (flags & stack_flags)
886 mm->stack_vm += pages;
887 if (flags & (VM_RESERVED|VM_IO))
888 mm->reserved_vm += pages;
889}
890#endif /* CONFIG_PROC_FS */
891
892/*
893 * The caller must hold down_write(current->mm->mmap_sem).
894 */
895
896unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
897 unsigned long len, unsigned long prot,
898 unsigned long flags, unsigned long pgoff)
899{
900 struct mm_struct * mm = current->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 struct inode *inode;
902 unsigned int vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 int accountable = 1;
Miklos Szeredi0165ab42007-07-15 23:38:26 -0700905 unsigned long reqprot = prot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 /*
908 * Does the application expect PROT_READ to imply PROT_EXEC?
909 *
910 * (the exception is when the underlying filesystem is noexec
911 * mounted, in which case we dont add PROT_EXEC.)
912 */
913 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800914 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 prot |= PROT_EXEC;
916
917 if (!len)
918 return -EINVAL;
919
Eric Paris7cd94142007-11-26 18:47:40 -0500920 if (!(flags & MAP_FIXED))
921 addr = round_hint_to_min(addr);
922
Kirill Korotaev3a459752006-09-07 14:17:04 +0400923 error = arch_mmap_check(addr, len, flags);
924 if (error)
925 return error;
926
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 /* Careful about overflows.. */
928 len = PAGE_ALIGN(len);
929 if (!len || len > TASK_SIZE)
930 return -ENOMEM;
931
932 /* offset overflow? */
933 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
934 return -EOVERFLOW;
935
936 /* Too many mappings? */
937 if (mm->map_count > sysctl_max_map_count)
938 return -ENOMEM;
939
940 /* Obtain the address to map to. we verify (or select) it and ensure
941 * that it represents a valid section of the address space.
942 */
943 addr = get_unmapped_area(file, addr, len, pgoff, flags);
944 if (addr & ~PAGE_MASK)
945 return addr;
946
947 /* Do simple checking here so the lower-level routines won't have
948 * to. we assume access permissions have been handled by the open
949 * of the memory object, so we don't do any here.
950 */
951 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
952 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
953
954 if (flags & MAP_LOCKED) {
955 if (!can_do_mlock())
956 return -EPERM;
957 vm_flags |= VM_LOCKED;
958 }
959 /* mlock MCL_FUTURE? */
960 if (vm_flags & VM_LOCKED) {
961 unsigned long locked, lock_limit;
Chris Wright93ea1d02005-05-01 08:58:38 -0700962 locked = len >> PAGE_SHIFT;
963 locked += mm->locked_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
Chris Wright93ea1d02005-05-01 08:58:38 -0700965 lock_limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
967 return -EAGAIN;
968 }
969
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800970 inode = file ? file->f_path.dentry->d_inode : NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971
972 if (file) {
973 switch (flags & MAP_TYPE) {
974 case MAP_SHARED:
975 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
976 return -EACCES;
977
978 /*
979 * Make sure we don't allow writing to an append-only
980 * file..
981 */
982 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
983 return -EACCES;
984
985 /*
986 * Make sure there are no mandatory locks on the file.
987 */
988 if (locks_verify_locked(inode))
989 return -EAGAIN;
990
991 vm_flags |= VM_SHARED | VM_MAYSHARE;
992 if (!(file->f_mode & FMODE_WRITE))
993 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
994
995 /* fall through */
996 case MAP_PRIVATE:
997 if (!(file->f_mode & FMODE_READ))
998 return -EACCES;
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -0800999 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
Linus Torvalds80c56062006-10-15 14:09:55 -07001000 if (vm_flags & VM_EXEC)
1001 return -EPERM;
1002 vm_flags &= ~VM_MAYEXEC;
1003 }
1004 if (is_file_hugepages(file))
1005 accountable = 0;
1006
1007 if (!file->f_op || !file->f_op->mmap)
1008 return -ENODEV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 break;
1010
1011 default:
1012 return -EINVAL;
1013 }
1014 } else {
1015 switch (flags & MAP_TYPE) {
1016 case MAP_SHARED:
1017 vm_flags |= VM_SHARED | VM_MAYSHARE;
1018 break;
1019 case MAP_PRIVATE:
1020 /*
1021 * Set pgoff according to addr for anon_vma.
1022 */
1023 pgoff = addr >> PAGE_SHIFT;
1024 break;
1025 default:
1026 return -EINVAL;
1027 }
1028 }
1029
Eric Parised032182007-06-28 15:55:21 -04001030 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031 if (error)
1032 return error;
Eric Parised032182007-06-28 15:55:21 -04001033
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001034 return mmap_region(file, addr, len, flags, vm_flags, pgoff,
1035 accountable);
1036}
1037EXPORT_SYMBOL(do_mmap_pgoff);
1038
Alexey Dobriyan4e950f62007-07-30 02:36:13 +04001039/*
1040 * Some shared mappigns will want the pages marked read-only
1041 * to track write events. If so, we'll downgrade vm_page_prot
1042 * to the private version (using protection_map[] without the
1043 * VM_SHARED bit).
1044 */
1045int vma_wants_writenotify(struct vm_area_struct *vma)
1046{
1047 unsigned int vm_flags = vma->vm_flags;
1048
1049 /* If it was private or non-writable, the write bit is already clear */
1050 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1051 return 0;
1052
1053 /* The backer wishes to know when pages are first written to? */
1054 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1055 return 1;
1056
1057 /* The open routine did something to the protections already? */
1058 if (pgprot_val(vma->vm_page_prot) !=
Coly Li3ed75eb2007-10-18 23:39:15 -07001059 pgprot_val(vm_get_page_prot(vm_flags)))
Alexey Dobriyan4e950f62007-07-30 02:36:13 +04001060 return 0;
1061
1062 /* Specialty mapping? */
1063 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1064 return 0;
1065
1066 /* Can the mapping track the dirty pages? */
1067 return vma->vm_file && vma->vm_file->f_mapping &&
1068 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1069}
1070
Miklos Szeredi0165ab42007-07-15 23:38:26 -07001071unsigned long mmap_region(struct file *file, unsigned long addr,
1072 unsigned long len, unsigned long flags,
1073 unsigned int vm_flags, unsigned long pgoff,
1074 int accountable)
1075{
1076 struct mm_struct *mm = current->mm;
1077 struct vm_area_struct *vma, *prev;
1078 int correct_wcount = 0;
1079 int error;
1080 struct rb_node **rb_link, *rb_parent;
1081 unsigned long charged = 0;
1082 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1083
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 /* Clear old maps */
1085 error = -ENOMEM;
1086munmap_back:
1087 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1088 if (vma && vma->vm_start < addr + len) {
1089 if (do_munmap(mm, addr, len))
1090 return -ENOMEM;
1091 goto munmap_back;
1092 }
1093
1094 /* Check against address space limit. */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001095 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 return -ENOMEM;
1097
1098 if (accountable && (!(flags & MAP_NORESERVE) ||
1099 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1100 if (vm_flags & VM_SHARED) {
1101 /* Check memory availability in shmem_file_setup? */
1102 vm_flags |= VM_ACCOUNT;
1103 } else if (vm_flags & VM_WRITE) {
1104 /*
1105 * Private writable mapping: check memory availability
1106 */
1107 charged = len >> PAGE_SHIFT;
1108 if (security_vm_enough_memory(charged))
1109 return -ENOMEM;
1110 vm_flags |= VM_ACCOUNT;
1111 }
1112 }
1113
1114 /*
1115 * Can we just expand an old private anonymous mapping?
1116 * The VM_SHARED test is necessary because shmem_zero_setup
1117 * will create the file object for a shared anonymous map below.
1118 */
1119 if (!file && !(vm_flags & VM_SHARED) &&
1120 vma_merge(mm, prev, addr, addr + len, vm_flags,
1121 NULL, NULL, pgoff, NULL))
1122 goto out;
1123
1124 /*
1125 * Determine the object being mapped and call the appropriate
1126 * specific mapper. the address has already been validated, but
1127 * not unmapped, but the maps are removed from the list.
1128 */
Pekka Enbergc5e3b832006-03-25 03:06:43 -08001129 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 if (!vma) {
1131 error = -ENOMEM;
1132 goto unacct_error;
1133 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134
1135 vma->vm_mm = mm;
1136 vma->vm_start = addr;
1137 vma->vm_end = addr + len;
1138 vma->vm_flags = vm_flags;
Coly Li3ed75eb2007-10-18 23:39:15 -07001139 vma->vm_page_prot = vm_get_page_prot(vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 vma->vm_pgoff = pgoff;
1141
1142 if (file) {
1143 error = -EINVAL;
1144 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1145 goto free_vma;
1146 if (vm_flags & VM_DENYWRITE) {
1147 error = deny_write_access(file);
1148 if (error)
1149 goto free_vma;
1150 correct_wcount = 1;
1151 }
1152 vma->vm_file = file;
1153 get_file(file);
1154 error = file->f_op->mmap(file, vma);
1155 if (error)
1156 goto unmap_and_free_vma;
1157 } else if (vm_flags & VM_SHARED) {
1158 error = shmem_zero_setup(vma);
1159 if (error)
1160 goto free_vma;
1161 }
1162
1163 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1164 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1165 * that memory reservation must be checked; but that reservation
1166 * belongs to shared memory object, not to vma: so now clear it.
1167 */
1168 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1169 vma->vm_flags &= ~VM_ACCOUNT;
1170
1171 /* Can addr have changed??
1172 *
1173 * Answer: Yes, several device drivers can do it in their
1174 * f_op->mmap method. -DaveM
1175 */
1176 addr = vma->vm_start;
1177 pgoff = vma->vm_pgoff;
1178 vm_flags = vma->vm_flags;
1179
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001180 if (vma_wants_writenotify(vma))
Hugh Dickins1ddd4392007-10-22 20:45:12 -07001181 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001182
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001183 if (file && vma_merge(mm, prev, addr, vma->vm_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
Lee Schermerhornf0be3d32008-04-28 02:13:08 -07001185 mpol_put(vma_policy(vma));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 kmem_cache_free(vm_area_cachep, vma);
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001187 fput(file);
1188 } else {
1189 vma_link(mm, vma, prev, rb_link, rb_parent);
1190 file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191 }
Oleg Nesterov4d3d5b42008-04-28 02:12:10 -07001192
1193 /* Once vma denies write, undo our temporary denial count */
1194 if (correct_wcount)
1195 atomic_inc(&inode->i_writecount);
1196out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 mm->total_vm += len >> PAGE_SHIFT;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -07001198 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199 if (vm_flags & VM_LOCKED) {
1200 mm->locked_vm += len >> PAGE_SHIFT;
1201 make_pages_present(addr, addr + len);
1202 }
Nick Piggin54cb8822007-07-19 01:46:59 -07001203 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1204 make_pages_present(addr, addr + len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 return addr;
1206
1207unmap_and_free_vma:
1208 if (correct_wcount)
1209 atomic_inc(&inode->i_writecount);
1210 vma->vm_file = NULL;
1211 fput(file);
1212
1213 /* Undo any partial mapping done by a device driver. */
Hugh Dickinse0da3822005-04-19 13:29:15 -07001214 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1215 charged = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216free_vma:
1217 kmem_cache_free(vm_area_cachep, vma);
1218unacct_error:
1219 if (charged)
1220 vm_unacct_memory(charged);
1221 return error;
1222}
1223
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224/* Get an address range which is currently unmapped.
1225 * For shmat() with addr=0.
1226 *
1227 * Ugly calling convention alert:
1228 * Return value with the low bits set means error value,
1229 * ie
1230 * if (ret & ~PAGE_MASK)
1231 * error = ret;
1232 *
1233 * This function "knows" that -ENOMEM has the bits set.
1234 */
1235#ifndef HAVE_ARCH_UNMAPPED_AREA
1236unsigned long
1237arch_get_unmapped_area(struct file *filp, unsigned long addr,
1238 unsigned long len, unsigned long pgoff, unsigned long flags)
1239{
1240 struct mm_struct *mm = current->mm;
1241 struct vm_area_struct *vma;
1242 unsigned long start_addr;
1243
1244 if (len > TASK_SIZE)
1245 return -ENOMEM;
1246
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001247 if (flags & MAP_FIXED)
1248 return addr;
1249
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 if (addr) {
1251 addr = PAGE_ALIGN(addr);
1252 vma = find_vma(mm, addr);
1253 if (TASK_SIZE - len >= addr &&
1254 (!vma || addr + len <= vma->vm_start))
1255 return addr;
1256 }
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001257 if (len > mm->cached_hole_size) {
1258 start_addr = addr = mm->free_area_cache;
1259 } else {
1260 start_addr = addr = TASK_UNMAPPED_BASE;
1261 mm->cached_hole_size = 0;
1262 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263
1264full_search:
1265 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1266 /* At this point: (!vma || addr < vma->vm_end). */
1267 if (TASK_SIZE - len < addr) {
1268 /*
1269 * Start a new search - just in case we missed
1270 * some holes.
1271 */
1272 if (start_addr != TASK_UNMAPPED_BASE) {
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001273 addr = TASK_UNMAPPED_BASE;
1274 start_addr = addr;
1275 mm->cached_hole_size = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 goto full_search;
1277 }
1278 return -ENOMEM;
1279 }
1280 if (!vma || addr + len <= vma->vm_start) {
1281 /*
1282 * Remember the place where we stopped the search:
1283 */
1284 mm->free_area_cache = addr + len;
1285 return addr;
1286 }
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001287 if (addr + mm->cached_hole_size < vma->vm_start)
1288 mm->cached_hole_size = vma->vm_start - addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 addr = vma->vm_end;
1290 }
1291}
1292#endif
1293
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001294void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295{
1296 /*
1297 * Is this a new hole at the lowest possible address?
1298 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001299 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1300 mm->free_area_cache = addr;
1301 mm->cached_hole_size = ~0UL;
1302 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303}
1304
1305/*
1306 * This mmap-allocator allocates new areas top-down from below the
1307 * stack's low limit (the base):
1308 */
1309#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1310unsigned long
1311arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1312 const unsigned long len, const unsigned long pgoff,
1313 const unsigned long flags)
1314{
1315 struct vm_area_struct *vma;
1316 struct mm_struct *mm = current->mm;
1317 unsigned long addr = addr0;
1318
1319 /* requested length too big for entire address space */
1320 if (len > TASK_SIZE)
1321 return -ENOMEM;
1322
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001323 if (flags & MAP_FIXED)
1324 return addr;
1325
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 /* requesting a specific address */
1327 if (addr) {
1328 addr = PAGE_ALIGN(addr);
1329 vma = find_vma(mm, addr);
1330 if (TASK_SIZE - len >= addr &&
1331 (!vma || addr + len <= vma->vm_start))
1332 return addr;
1333 }
1334
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001335 /* check if free_area_cache is useful for us */
1336 if (len <= mm->cached_hole_size) {
1337 mm->cached_hole_size = 0;
1338 mm->free_area_cache = mm->mmap_base;
1339 }
1340
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 /* either no address requested or can't fit in requested address hole */
1342 addr = mm->free_area_cache;
1343
1344 /* make sure it can fit in the remaining address space */
Linus Torvalds49a43872005-05-18 15:39:33 -07001345 if (addr > len) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 vma = find_vma(mm, addr-len);
1347 if (!vma || addr <= vma->vm_start)
1348 /* remember the address as a hint for next time */
1349 return (mm->free_area_cache = addr-len);
1350 }
1351
Chris Wright73219d12005-06-21 17:14:52 -07001352 if (mm->mmap_base < len)
1353 goto bottomup;
1354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 addr = mm->mmap_base-len;
1356
1357 do {
1358 /*
1359 * Lookup failure means no vma is above this address,
1360 * else if new region fits below vma->vm_start,
1361 * return with success:
1362 */
1363 vma = find_vma(mm, addr);
1364 if (!vma || addr+len <= vma->vm_start)
1365 /* remember the address as a hint for next time */
1366 return (mm->free_area_cache = addr);
1367
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001368 /* remember the largest hole we saw so far */
1369 if (addr + mm->cached_hole_size < vma->vm_start)
1370 mm->cached_hole_size = vma->vm_start - addr;
1371
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 /* try just below the current vma->vm_start */
1373 addr = vma->vm_start-len;
Linus Torvalds49a43872005-05-18 15:39:33 -07001374 } while (len < vma->vm_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375
Chris Wright73219d12005-06-21 17:14:52 -07001376bottomup:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 /*
1378 * A failed mmap() very likely causes application failure,
1379 * so fall back to the bottom-up function here. This scenario
1380 * can happen with large stack limits and large mmap()
1381 * allocations.
1382 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001383 mm->cached_hole_size = ~0UL;
1384 mm->free_area_cache = TASK_UNMAPPED_BASE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1386 /*
1387 * Restore the topdown base:
1388 */
1389 mm->free_area_cache = mm->mmap_base;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001390 mm->cached_hole_size = ~0UL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391
1392 return addr;
1393}
1394#endif
1395
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001396void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397{
1398 /*
1399 * Is this a new hole at the highest possible address?
1400 */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001401 if (addr > mm->free_area_cache)
1402 mm->free_area_cache = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
1404 /* dont allow allocations above current base */
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001405 if (mm->free_area_cache > mm->mmap_base)
1406 mm->free_area_cache = mm->mmap_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407}
1408
1409unsigned long
1410get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1411 unsigned long pgoff, unsigned long flags)
1412{
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001413 unsigned long (*get_area)(struct file *, unsigned long,
1414 unsigned long, unsigned long, unsigned long);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001416 get_area = current->mm->get_unmapped_area;
1417 if (file && file->f_op && file->f_op->get_unmapped_area)
1418 get_area = file->f_op->get_unmapped_area;
1419 addr = get_area(file, addr, len, pgoff, flags);
1420 if (IS_ERR_VALUE(addr))
1421 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422
Linus Torvalds07ab67c2005-05-19 22:43:37 -07001423 if (addr > TASK_SIZE - len)
1424 return -ENOMEM;
1425 if (addr & ~PAGE_MASK)
1426 return -EINVAL;
Benjamin Herrenschmidt06abdfb2007-05-06 14:50:13 -07001427
Martin Schwidefsky08e7d9b2008-02-04 22:29:16 -08001428 return arch_rebalance_pgtables(addr, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429}
1430
1431EXPORT_SYMBOL(get_unmapped_area);
1432
1433/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1434struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1435{
1436 struct vm_area_struct *vma = NULL;
1437
1438 if (mm) {
1439 /* Check the cache first. */
1440 /* (Cache hit rate is typically around 35%.) */
1441 vma = mm->mmap_cache;
1442 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1443 struct rb_node * rb_node;
1444
1445 rb_node = mm->mm_rb.rb_node;
1446 vma = NULL;
1447
1448 while (rb_node) {
1449 struct vm_area_struct * vma_tmp;
1450
1451 vma_tmp = rb_entry(rb_node,
1452 struct vm_area_struct, vm_rb);
1453
1454 if (vma_tmp->vm_end > addr) {
1455 vma = vma_tmp;
1456 if (vma_tmp->vm_start <= addr)
1457 break;
1458 rb_node = rb_node->rb_left;
1459 } else
1460 rb_node = rb_node->rb_right;
1461 }
1462 if (vma)
1463 mm->mmap_cache = vma;
1464 }
1465 }
1466 return vma;
1467}
1468
1469EXPORT_SYMBOL(find_vma);
1470
1471/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1472struct vm_area_struct *
1473find_vma_prev(struct mm_struct *mm, unsigned long addr,
1474 struct vm_area_struct **pprev)
1475{
1476 struct vm_area_struct *vma = NULL, *prev = NULL;
1477 struct rb_node * rb_node;
1478 if (!mm)
1479 goto out;
1480
1481 /* Guard against addr being lower than the first VMA */
1482 vma = mm->mmap;
1483
1484 /* Go through the RB tree quickly. */
1485 rb_node = mm->mm_rb.rb_node;
1486
1487 while (rb_node) {
1488 struct vm_area_struct *vma_tmp;
1489 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1490
1491 if (addr < vma_tmp->vm_end) {
1492 rb_node = rb_node->rb_left;
1493 } else {
1494 prev = vma_tmp;
1495 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1496 break;
1497 rb_node = rb_node->rb_right;
1498 }
1499 }
1500
1501out:
1502 *pprev = prev;
1503 return prev ? prev->vm_next : vma;
1504}
1505
1506/*
1507 * Verify that the stack growth is acceptable and
1508 * update accounting. This is shared with both the
1509 * grow-up and grow-down cases.
1510 */
1511static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1512{
1513 struct mm_struct *mm = vma->vm_mm;
1514 struct rlimit *rlim = current->signal->rlim;
Adam Litke0d59a012007-01-30 14:35:39 -08001515 unsigned long new_start;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516
1517 /* address space limit tests */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001518 if (!may_expand_vm(mm, grow))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 return -ENOMEM;
1520
1521 /* Stack limit test */
1522 if (size > rlim[RLIMIT_STACK].rlim_cur)
1523 return -ENOMEM;
1524
1525 /* mlock limit tests */
1526 if (vma->vm_flags & VM_LOCKED) {
1527 unsigned long locked;
1528 unsigned long limit;
1529 locked = mm->locked_vm + grow;
1530 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1531 if (locked > limit && !capable(CAP_IPC_LOCK))
1532 return -ENOMEM;
1533 }
1534
Adam Litke0d59a012007-01-30 14:35:39 -08001535 /* Check to ensure the stack will not grow into a hugetlb-only region */
1536 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1537 vma->vm_end - size;
1538 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1539 return -EFAULT;
1540
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 /*
1542 * Overcommit.. This must be the final test, as it will
1543 * update security statistics.
1544 */
1545 if (security_vm_enough_memory(grow))
1546 return -ENOMEM;
1547
1548 /* Ok, everything looks good - let it rip */
1549 mm->total_vm += grow;
1550 if (vma->vm_flags & VM_LOCKED)
1551 mm->locked_vm += grow;
Hugh Dickinsab50b8e2005-10-29 18:15:56 -07001552 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 return 0;
1554}
1555
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001556#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557/*
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001558 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1559 * vma is the last one with address > vma->vm_end. Have to extend vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 */
Matthew Wilcox9ab88512005-11-18 16:16:42 -05001561#ifndef CONFIG_IA64
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001562static inline
1563#endif
1564int expand_upwards(struct vm_area_struct *vma, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565{
1566 int error;
1567
1568 if (!(vma->vm_flags & VM_GROWSUP))
1569 return -EFAULT;
1570
1571 /*
1572 * We must make sure the anon_vma is allocated
1573 * so that the anon_vma locking is not a noop.
1574 */
1575 if (unlikely(anon_vma_prepare(vma)))
1576 return -ENOMEM;
1577 anon_vma_lock(vma);
1578
1579 /*
1580 * vma->vm_start/vm_end cannot change under us because the caller
1581 * is required to hold the mmap_sem in read mode. We need the
1582 * anon_vma lock to serialize against concurrent expand_stacks.
Helge Deller06b32f32006-12-19 19:28:33 +01001583 * Also guard against wrapping around to address 0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 */
Helge Deller06b32f32006-12-19 19:28:33 +01001585 if (address < PAGE_ALIGN(address+4))
1586 address = PAGE_ALIGN(address+4);
1587 else {
1588 anon_vma_unlock(vma);
1589 return -ENOMEM;
1590 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 error = 0;
1592
1593 /* Somebody else might have raced and expanded it already */
1594 if (address > vma->vm_end) {
1595 unsigned long size, grow;
1596
1597 size = address - vma->vm_start;
1598 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1599
1600 error = acct_stack_growth(vma, size, grow);
1601 if (!error)
1602 vma->vm_end = address;
1603 }
1604 anon_vma_unlock(vma);
1605 return error;
1606}
Hugh Dickins46dea3d2005-10-29 18:16:20 -07001607#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1608
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609/*
1610 * vma is the first one with address < vma->vm_start. Have to extend vma.
1611 */
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001612static inline int expand_downwards(struct vm_area_struct *vma,
1613 unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614{
1615 int error;
1616
1617 /*
1618 * We must make sure the anon_vma is allocated
1619 * so that the anon_vma locking is not a noop.
1620 */
1621 if (unlikely(anon_vma_prepare(vma)))
1622 return -ENOMEM;
Eric Paris88694772007-11-26 18:47:26 -05001623
1624 address &= PAGE_MASK;
Richard Knutsson88c3f7a2007-12-08 12:02:48 +01001625 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
Eric Paris88694772007-11-26 18:47:26 -05001626 if (error)
1627 return error;
1628
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 anon_vma_lock(vma);
1630
1631 /*
1632 * vma->vm_start/vm_end cannot change under us because the caller
1633 * is required to hold the mmap_sem in read mode. We need the
1634 * anon_vma lock to serialize against concurrent expand_stacks.
1635 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636
1637 /* Somebody else might have raced and expanded it already */
1638 if (address < vma->vm_start) {
1639 unsigned long size, grow;
1640
1641 size = vma->vm_end - address;
1642 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1643
1644 error = acct_stack_growth(vma, size, grow);
1645 if (!error) {
1646 vma->vm_start = address;
1647 vma->vm_pgoff -= grow;
1648 }
1649 }
1650 anon_vma_unlock(vma);
1651 return error;
1652}
1653
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001654int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1655{
1656 return expand_downwards(vma, address);
1657}
1658
1659#ifdef CONFIG_STACK_GROWSUP
1660int expand_stack(struct vm_area_struct *vma, unsigned long address)
1661{
1662 return expand_upwards(vma, address);
1663}
1664
1665struct vm_area_struct *
1666find_extend_vma(struct mm_struct *mm, unsigned long addr)
1667{
1668 struct vm_area_struct *vma, *prev;
1669
1670 addr &= PAGE_MASK;
1671 vma = find_vma_prev(mm, addr, &prev);
1672 if (vma && (vma->vm_start <= addr))
1673 return vma;
1674 if (!prev || expand_stack(prev, addr))
1675 return NULL;
1676 if (prev->vm_flags & VM_LOCKED)
1677 make_pages_present(addr, prev->vm_end);
1678 return prev;
1679}
1680#else
1681int expand_stack(struct vm_area_struct *vma, unsigned long address)
1682{
1683 return expand_downwards(vma, address);
1684}
1685
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686struct vm_area_struct *
1687find_extend_vma(struct mm_struct * mm, unsigned long addr)
1688{
1689 struct vm_area_struct * vma;
1690 unsigned long start;
1691
1692 addr &= PAGE_MASK;
1693 vma = find_vma(mm,addr);
1694 if (!vma)
1695 return NULL;
1696 if (vma->vm_start <= addr)
1697 return vma;
1698 if (!(vma->vm_flags & VM_GROWSDOWN))
1699 return NULL;
1700 start = vma->vm_start;
1701 if (expand_stack(vma, addr))
1702 return NULL;
Ollie Wildb6a2fea2007-07-19 01:48:16 -07001703 if (vma->vm_flags & VM_LOCKED)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 make_pages_present(addr, start);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705 return vma;
1706}
1707#endif
1708
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709/*
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001710 * Ok - we have the memory areas we should free on the vma list,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 * so release them, and do the vma updates.
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001712 *
1713 * Called with the mm semaphore held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714 */
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001715static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716{
Hugh Dickins365e9c872005-10-29 18:16:18 -07001717 /* Update high watermark before we lower total_vm */
1718 update_hiwater_vm(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 do {
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001720 long nrpages = vma_pages(vma);
1721
1722 mm->total_vm -= nrpages;
1723 if (vma->vm_flags & VM_LOCKED)
1724 mm->locked_vm -= nrpages;
1725 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
Hugh Dickinsa8fb5612005-10-29 18:15:57 -07001726 vma = remove_vma(vma);
Hugh Dickins146425a2005-04-19 13:29:18 -07001727 } while (vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728 validate_mm(mm);
1729}
1730
1731/*
1732 * Get rid of page table information in the indicated region.
1733 *
Paolo 'Blaisorblade' Giarrussof10df682005-09-21 09:55:37 -07001734 * Called with the mm semaphore held.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735 */
1736static void unmap_region(struct mm_struct *mm,
Hugh Dickinse0da3822005-04-19 13:29:15 -07001737 struct vm_area_struct *vma, struct vm_area_struct *prev,
1738 unsigned long start, unsigned long end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739{
Hugh Dickinse0da3822005-04-19 13:29:15 -07001740 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 struct mmu_gather *tlb;
1742 unsigned long nr_accounted = 0;
1743
1744 lru_add_drain();
1745 tlb = tlb_gather_mmu(mm, 0);
Hugh Dickins365e9c872005-10-29 18:16:18 -07001746 update_hiwater_rss(mm);
Hugh Dickins508034a2005-10-29 18:16:30 -07001747 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 vm_unacct_memory(nr_accounted);
Hugh Dickinse2cdef82005-04-19 13:29:19 -07001749 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
Hugh Dickinse0da3822005-04-19 13:29:15 -07001750 next? next->vm_start: 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 tlb_finish_mmu(tlb, start, end);
1752}
1753
1754/*
1755 * Create a list of vma's touched by the unmap, removing them from the mm's
1756 * vma list as we go..
1757 */
1758static void
1759detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1760 struct vm_area_struct *prev, unsigned long end)
1761{
1762 struct vm_area_struct **insertion_point;
1763 struct vm_area_struct *tail_vma = NULL;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001764 unsigned long addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765
1766 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1767 do {
1768 rb_erase(&vma->vm_rb, &mm->mm_rb);
1769 mm->map_count--;
1770 tail_vma = vma;
1771 vma = vma->vm_next;
1772 } while (vma && vma->vm_start < end);
1773 *insertion_point = vma;
1774 tail_vma->vm_next = NULL;
Wolfgang Wander1363c3c2005-06-21 17:14:49 -07001775 if (mm->unmap_area == arch_unmap_area)
1776 addr = prev ? prev->vm_end : mm->mmap_base;
1777 else
1778 addr = vma ? vma->vm_start : mm->mmap_base;
1779 mm->unmap_area(mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 mm->mmap_cache = NULL; /* Kill the cache. */
1781}
1782
1783/*
1784 * Split a vma into two pieces at address 'addr', a new vma is allocated
Michael Opdenacker59c51592007-05-09 08:57:56 +02001785 * either for the first part or the tail.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 */
1787int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1788 unsigned long addr, int new_below)
1789{
1790 struct mempolicy *pol;
1791 struct vm_area_struct *new;
1792
1793 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1794 return -EINVAL;
1795
1796 if (mm->map_count >= sysctl_max_map_count)
1797 return -ENOMEM;
1798
Christoph Lametere94b1762006-12-06 20:33:17 -08001799 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 if (!new)
1801 return -ENOMEM;
1802
1803 /* most fields are the same, copy all, and then fixup */
1804 *new = *vma;
1805
1806 if (new_below)
1807 new->vm_end = addr;
1808 else {
1809 new->vm_start = addr;
1810 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1811 }
1812
1813 pol = mpol_copy(vma_policy(vma));
1814 if (IS_ERR(pol)) {
1815 kmem_cache_free(vm_area_cachep, new);
1816 return PTR_ERR(pol);
1817 }
1818 vma_set_policy(new, pol);
1819
1820 if (new->vm_file)
1821 get_file(new->vm_file);
1822
1823 if (new->vm_ops && new->vm_ops->open)
1824 new->vm_ops->open(new);
1825
1826 if (new_below)
1827 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1828 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1829 else
1830 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1831
1832 return 0;
1833}
1834
1835/* Munmap is split into 2 main parts -- this part which finds
1836 * what needs doing, and the areas themselves, which do the
1837 * work. This now handles partial unmappings.
1838 * Jeremy Fitzhardinge <jeremy@goop.org>
1839 */
1840int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1841{
1842 unsigned long end;
Hugh Dickins146425a2005-04-19 13:29:18 -07001843 struct vm_area_struct *vma, *prev, *last;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844
1845 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1846 return -EINVAL;
1847
1848 if ((len = PAGE_ALIGN(len)) == 0)
1849 return -EINVAL;
1850
1851 /* Find the first overlapping VMA */
Hugh Dickins146425a2005-04-19 13:29:18 -07001852 vma = find_vma_prev(mm, start, &prev);
1853 if (!vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854 return 0;
Hugh Dickins146425a2005-04-19 13:29:18 -07001855 /* we have start < vma->vm_end */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856
1857 /* if it doesn't overlap, we have nothing.. */
1858 end = start + len;
Hugh Dickins146425a2005-04-19 13:29:18 -07001859 if (vma->vm_start >= end)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001860 return 0;
1861
1862 /*
1863 * If we need to split any vma, do it now to save pain later.
1864 *
1865 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1866 * unmapped vm_area_struct will remain in use: so lower split_vma
1867 * places tmp vma above, and higher split_vma places tmp vma below.
1868 */
Hugh Dickins146425a2005-04-19 13:29:18 -07001869 if (start > vma->vm_start) {
1870 int error = split_vma(mm, vma, start, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 if (error)
1872 return error;
Hugh Dickins146425a2005-04-19 13:29:18 -07001873 prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 }
1875
1876 /* Does it split the last one? */
1877 last = find_vma(mm, end);
1878 if (last && end > last->vm_start) {
1879 int error = split_vma(mm, last, end, 1);
1880 if (error)
1881 return error;
1882 }
Hugh Dickins146425a2005-04-19 13:29:18 -07001883 vma = prev? prev->vm_next: mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884
1885 /*
1886 * Remove the vma's, and unmap the actual pages
1887 */
Hugh Dickins146425a2005-04-19 13:29:18 -07001888 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1889 unmap_region(mm, vma, prev, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890
1891 /* Fix up all other VM information */
Hugh Dickins2c0b3812005-10-29 18:15:56 -07001892 remove_vma_list(mm, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
1894 return 0;
1895}
1896
1897EXPORT_SYMBOL(do_munmap);
1898
1899asmlinkage long sys_munmap(unsigned long addr, size_t len)
1900{
1901 int ret;
1902 struct mm_struct *mm = current->mm;
1903
1904 profile_munmap(addr);
1905
1906 down_write(&mm->mmap_sem);
1907 ret = do_munmap(mm, addr, len);
1908 up_write(&mm->mmap_sem);
1909 return ret;
1910}
1911
1912static inline void verify_mm_writelocked(struct mm_struct *mm)
1913{
Paul E. McKenneya241ec62005-10-30 15:03:12 -08001914#ifdef CONFIG_DEBUG_VM
Linus Torvalds1da177e2005-04-16 15:20:36 -07001915 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1916 WARN_ON(1);
1917 up_read(&mm->mmap_sem);
1918 }
1919#endif
1920}
1921
1922/*
1923 * this is really a simplified "do_mmap". it only handles
1924 * anonymous maps. eventually we may be able to do some
1925 * brk-specific accounting here.
1926 */
1927unsigned long do_brk(unsigned long addr, unsigned long len)
1928{
1929 struct mm_struct * mm = current->mm;
1930 struct vm_area_struct * vma, * prev;
1931 unsigned long flags;
1932 struct rb_node ** rb_link, * rb_parent;
1933 pgoff_t pgoff = addr >> PAGE_SHIFT;
Kirill Korotaev3a459752006-09-07 14:17:04 +04001934 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935
1936 len = PAGE_ALIGN(len);
1937 if (!len)
1938 return addr;
1939
1940 if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1941 return -EINVAL;
1942
Hugh Dickinscd2579d2006-11-14 13:43:38 +00001943 if (is_hugepage_only_range(mm, addr, len))
1944 return -EINVAL;
David Gibsoncb07c9a2006-11-14 02:03:38 -08001945
Richard Knutsson88c3f7a2007-12-08 12:02:48 +01001946 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
Eric Paris5a211a52007-12-04 11:06:55 -05001947 if (error)
1948 return error;
1949
Kirill Korotaev3a459752006-09-07 14:17:04 +04001950 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1951
1952 error = arch_mmap_check(addr, len, flags);
1953 if (error)
1954 return error;
1955
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956 /*
1957 * mlock MCL_FUTURE?
1958 */
1959 if (mm->def_flags & VM_LOCKED) {
1960 unsigned long locked, lock_limit;
Chris Wright93ea1d02005-05-01 08:58:38 -07001961 locked = len >> PAGE_SHIFT;
1962 locked += mm->locked_vm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
Chris Wright93ea1d02005-05-01 08:58:38 -07001964 lock_limit >>= PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1966 return -EAGAIN;
1967 }
1968
1969 /*
1970 * mm->mmap_sem is required to protect against another thread
1971 * changing the mappings in case we sleep.
1972 */
1973 verify_mm_writelocked(mm);
1974
1975 /*
1976 * Clear old maps. this also does some error checking for us
1977 */
1978 munmap_back:
1979 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1980 if (vma && vma->vm_start < addr + len) {
1981 if (do_munmap(mm, addr, len))
1982 return -ENOMEM;
1983 goto munmap_back;
1984 }
1985
1986 /* Check against address space limits *after* clearing old maps... */
akpm@osdl.org119f6572005-05-01 08:58:35 -07001987 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988 return -ENOMEM;
1989
1990 if (mm->map_count > sysctl_max_map_count)
1991 return -ENOMEM;
1992
1993 if (security_vm_enough_memory(len >> PAGE_SHIFT))
1994 return -ENOMEM;
1995
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996 /* Can we just expand an old private anonymous mapping? */
1997 if (vma_merge(mm, prev, addr, addr + len, flags,
1998 NULL, NULL, pgoff, NULL))
1999 goto out;
2000
2001 /*
2002 * create a vma struct for an anonymous mapping
2003 */
Pekka Enbergc5e3b832006-03-25 03:06:43 -08002004 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005 if (!vma) {
2006 vm_unacct_memory(len >> PAGE_SHIFT);
2007 return -ENOMEM;
2008 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009
2010 vma->vm_mm = mm;
2011 vma->vm_start = addr;
2012 vma->vm_end = addr + len;
2013 vma->vm_pgoff = pgoff;
2014 vma->vm_flags = flags;
Coly Li3ed75eb2007-10-18 23:39:15 -07002015 vma->vm_page_prot = vm_get_page_prot(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 vma_link(mm, vma, prev, rb_link, rb_parent);
2017out:
2018 mm->total_vm += len >> PAGE_SHIFT;
2019 if (flags & VM_LOCKED) {
2020 mm->locked_vm += len >> PAGE_SHIFT;
2021 make_pages_present(addr, addr + len);
2022 }
2023 return addr;
2024}
2025
2026EXPORT_SYMBOL(do_brk);
2027
2028/* Release all mmaps. */
2029void exit_mmap(struct mm_struct *mm)
2030{
2031 struct mmu_gather *tlb;
Hugh Dickinse0da3822005-04-19 13:29:15 -07002032 struct vm_area_struct *vma = mm->mmap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 unsigned long nr_accounted = 0;
Hugh Dickinsee39b372005-04-19 13:29:15 -07002034 unsigned long end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035
Jeremy Fitzhardinged6dd61c2007-05-02 19:27:14 +02002036 /* mm's last user has gone, and its about to be pulled down */
2037 arch_exit_mmap(mm);
2038
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 lru_add_drain();
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040 flush_cache_mm(mm);
Hugh Dickinse0da3822005-04-19 13:29:15 -07002041 tlb = tlb_gather_mmu(mm, 1);
Hugh Dickins365e9c872005-10-29 18:16:18 -07002042 /* Don't update_hiwater_rss(mm) here, do_exit already did */
Hugh Dickinse0da3822005-04-19 13:29:15 -07002043 /* Use -1 here to ensure all VMAs in the mm are unmapped */
Hugh Dickins508034a2005-10-29 18:16:30 -07002044 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045 vm_unacct_memory(nr_accounted);
Hugh Dickinse2cdef82005-04-19 13:29:19 -07002046 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
Hugh Dickinsee39b372005-04-19 13:29:15 -07002047 tlb_finish_mmu(tlb, 0, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 /*
Hugh Dickins8f4f8c12005-10-29 18:16:29 -07002050 * Walk the list again, actually closing and freeing it,
2051 * with preemption enabled, without holding any MM locks.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052 */
Hugh Dickinsa8fb5612005-10-29 18:15:57 -07002053 while (vma)
2054 vma = remove_vma(vma);
Hugh Dickinse0da3822005-04-19 13:29:15 -07002055
Hugh Dickinse2cdef82005-04-19 13:29:19 -07002056 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057}
2058
2059/* Insert vm structure into process list sorted by address
2060 * and into the inode's i_mmap tree. If vm_file is non-NULL
2061 * then i_mmap_lock is taken here.
2062 */
2063int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2064{
2065 struct vm_area_struct * __vma, * prev;
2066 struct rb_node ** rb_link, * rb_parent;
2067
2068 /*
2069 * The vm_pgoff of a purely anonymous vma should be irrelevant
2070 * until its first write fault, when page's anon_vma and index
2071 * are set. But now set the vm_pgoff it will almost certainly
2072 * end up with (unless mremap moves it elsewhere before that
2073 * first wfault), so /proc/pid/maps tells a consistent story.
2074 *
2075 * By setting it to reflect the virtual start address of the
2076 * vma, merges and splits can happen in a seamless way, just
2077 * using the existing file pgoff checks and manipulations.
2078 * Similarly in do_mmap_pgoff and in do_brk.
2079 */
2080 if (!vma->vm_file) {
2081 BUG_ON(vma->anon_vma);
2082 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2083 }
2084 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2085 if (__vma && __vma->vm_start < vma->vm_end)
2086 return -ENOMEM;
Hugh Dickins2fd4ef82005-09-14 06:13:02 +01002087 if ((vma->vm_flags & VM_ACCOUNT) &&
Alan Cox34b4e4a2007-08-22 14:01:28 -07002088 security_vm_enough_memory_mm(mm, vma_pages(vma)))
Hugh Dickins2fd4ef82005-09-14 06:13:02 +01002089 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 vma_link(mm, vma, prev, rb_link, rb_parent);
2091 return 0;
2092}
2093
2094/*
2095 * Copy the vma structure to a new location in the same mm,
2096 * prior to moving page table entries, to effect an mremap move.
2097 */
2098struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2099 unsigned long addr, unsigned long len, pgoff_t pgoff)
2100{
2101 struct vm_area_struct *vma = *vmap;
2102 unsigned long vma_start = vma->vm_start;
2103 struct mm_struct *mm = vma->vm_mm;
2104 struct vm_area_struct *new_vma, *prev;
2105 struct rb_node **rb_link, *rb_parent;
2106 struct mempolicy *pol;
2107
2108 /*
2109 * If anonymous vma has not yet been faulted, update new pgoff
2110 * to match new location, to increase its chance of merging.
2111 */
2112 if (!vma->vm_file && !vma->anon_vma)
2113 pgoff = addr >> PAGE_SHIFT;
2114
2115 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2116 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2117 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2118 if (new_vma) {
2119 /*
2120 * Source vma may have been merged into new_vma
2121 */
2122 if (vma_start >= new_vma->vm_start &&
2123 vma_start < new_vma->vm_end)
2124 *vmap = new_vma;
2125 } else {
Christoph Lametere94b1762006-12-06 20:33:17 -08002126 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002127 if (new_vma) {
2128 *new_vma = *vma;
2129 pol = mpol_copy(vma_policy(vma));
2130 if (IS_ERR(pol)) {
2131 kmem_cache_free(vm_area_cachep, new_vma);
2132 return NULL;
2133 }
2134 vma_set_policy(new_vma, pol);
2135 new_vma->vm_start = addr;
2136 new_vma->vm_end = addr + len;
2137 new_vma->vm_pgoff = pgoff;
2138 if (new_vma->vm_file)
2139 get_file(new_vma->vm_file);
2140 if (new_vma->vm_ops && new_vma->vm_ops->open)
2141 new_vma->vm_ops->open(new_vma);
2142 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2143 }
2144 }
2145 return new_vma;
2146}
akpm@osdl.org119f6572005-05-01 08:58:35 -07002147
2148/*
2149 * Return true if the calling process may expand its vm space by the passed
2150 * number of pages
2151 */
2152int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2153{
2154 unsigned long cur = mm->total_vm; /* pages */
2155 unsigned long lim;
2156
2157 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2158
2159 if (cur + npages > lim)
2160 return 0;
2161 return 1;
2162}
Roland McGrathfa5dc222007-02-08 14:20:41 -08002163
2164
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002165static int special_mapping_fault(struct vm_area_struct *vma,
2166 struct vm_fault *vmf)
Roland McGrathfa5dc222007-02-08 14:20:41 -08002167{
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002168 pgoff_t pgoff;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002169 struct page **pages;
2170
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002171 /*
2172 * special mappings have no vm_file, and in that case, the mm
2173 * uses vm_pgoff internally. So we have to subtract it from here.
2174 * We are allowed to do this because we are the mm; do not copy
2175 * this code into drivers!
2176 */
2177 pgoff = vmf->pgoff - vma->vm_pgoff;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002178
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002179 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2180 pgoff--;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002181
2182 if (*pages) {
2183 struct page *page = *pages;
2184 get_page(page);
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002185 vmf->page = page;
2186 return 0;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002187 }
2188
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002189 return VM_FAULT_SIGBUS;
Roland McGrathfa5dc222007-02-08 14:20:41 -08002190}
2191
2192/*
2193 * Having a close hook prevents vma merging regardless of flags.
2194 */
2195static void special_mapping_close(struct vm_area_struct *vma)
2196{
2197}
2198
2199static struct vm_operations_struct special_mapping_vmops = {
2200 .close = special_mapping_close,
Nick Pigginb1d0e4f2008-02-09 01:15:19 +01002201 .fault = special_mapping_fault,
Roland McGrathfa5dc222007-02-08 14:20:41 -08002202};
2203
2204/*
2205 * Called with mm->mmap_sem held for writing.
2206 * Insert a new vma covering the given region, with the given flags.
2207 * Its pages are supplied by the given array of struct page *.
2208 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2209 * The region past the last page supplied will always produce SIGBUS.
2210 * The array pointer and the pages it points to are assumed to stay alive
2211 * for as long as this mapping might exist.
2212 */
2213int install_special_mapping(struct mm_struct *mm,
2214 unsigned long addr, unsigned long len,
2215 unsigned long vm_flags, struct page **pages)
2216{
2217 struct vm_area_struct *vma;
2218
2219 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2220 if (unlikely(vma == NULL))
2221 return -ENOMEM;
2222
2223 vma->vm_mm = mm;
2224 vma->vm_start = addr;
2225 vma->vm_end = addr + len;
2226
Nick Piggin2f987352008-02-02 03:08:53 +01002227 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
Coly Li3ed75eb2007-10-18 23:39:15 -07002228 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
Roland McGrathfa5dc222007-02-08 14:20:41 -08002229
2230 vma->vm_ops = &special_mapping_vmops;
2231 vma->vm_private_data = pages;
2232
2233 if (unlikely(insert_vm_struct(mm, vma))) {
2234 kmem_cache_free(vm_area_cachep, vma);
2235 return -ENOMEM;
2236 }
2237
2238 mm->total_vm += len >> PAGE_SHIFT;
2239
2240 return 0;
2241}