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1 | /* |
2 | * mm/mmap.c |
3 | * |
4 | * Written by obz. |
5 | * |
6 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
7 | */ |
8 | |
9 | #include <linux/slab.h> |
10 | #include <linux/backing-dev.h> |
11 | #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> |
17 | #include <linux/capability.h> |
18 | #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 | #include <linux/mmu_notifier.h> |
30 | #include <linux/perf_event.h> |
31 | #include <linux/audit.h> |
32 | #include <linux/khugepaged.h> |
33 | |
34 | #include <asm/uaccess.h> |
35 | #include <asm/cacheflush.h> |
36 | #include <asm/tlb.h> |
37 | #include <asm/mmu_context.h> |
38 | |
39 | #include "internal.h" |
40 | |
41 | #ifndef arch_mmap_check |
42 | #define arch_mmap_check(addr, len, flags) (0) |
43 | #endif |
44 | |
45 | #ifndef arch_rebalance_pgtables |
46 | #define arch_rebalance_pgtables(addr, len) (addr) |
47 | #endif |
48 | |
49 | static void unmap_region(struct mm_struct *mm, |
50 | struct vm_area_struct *vma, struct vm_area_struct *prev, |
51 | unsigned long start, unsigned long end); |
52 | |
53 | /* |
54 | * WARNING: the debugging will use recursive algorithms so never enable this |
55 | * unless you know what you are doing. |
56 | */ |
57 | #undef DEBUG_MM_RB |
58 | |
59 | /* description of effects of mapping type and prot in current implementation. |
60 | * this is due to the limited x86 page protection hardware. The expected |
61 | * behavior is in parens: |
62 | * |
63 | * map_type prot |
64 | * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC |
65 | * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes |
66 | * w: (no) no w: (no) no w: (yes) yes w: (no) no |
67 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes |
68 | * |
69 | * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes |
70 | * w: (no) no w: (no) no w: (copy) copy w: (no) no |
71 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes |
72 | * |
73 | */ |
74 | pgprot_t protection_map[16] = { |
75 | __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, |
76 | __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 |
77 | }; |
78 | |
79 | pgprot_t vm_get_page_prot(unsigned long vm_flags) |
80 | { |
81 | return __pgprot(pgprot_val(protection_map[vm_flags & |
82 | (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | |
83 | pgprot_val(arch_vm_get_page_prot(vm_flags))); |
84 | } |
85 | EXPORT_SYMBOL(vm_get_page_prot); |
86 | |
87 | int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ |
88 | int sysctl_overcommit_ratio = 50; /* default is 50% */ |
89 | int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; |
90 | struct percpu_counter vm_committed_as; |
91 | |
92 | /* |
93 | * Check that a process has enough memory to allocate a new virtual |
94 | * mapping. 0 means there is enough memory for the allocation to |
95 | * succeed and -ENOMEM implies there is not. |
96 | * |
97 | * We currently support three overcommit policies, which are set via the |
98 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting |
99 | * |
100 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. |
101 | * Additional code 2002 Jul 20 by Robert Love. |
102 | * |
103 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. |
104 | * |
105 | * Note this is a helper function intended to be used by LSMs which |
106 | * wish to use this logic. |
107 | */ |
108 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) |
109 | { |
110 | unsigned long free, allowed; |
111 | |
112 | vm_acct_memory(pages); |
113 | |
114 | /* |
115 | * Sometimes we want to use more memory than we have |
116 | */ |
117 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) |
118 | return 0; |
119 | |
120 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { |
121 | unsigned long n; |
122 | |
123 | free = global_page_state(NR_FILE_PAGES); |
124 | free += nr_swap_pages; |
125 | |
126 | /* |
127 | * Any slabs which are created with the |
128 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents |
129 | * which are reclaimable, under pressure. The dentry |
130 | * cache and most inode caches should fall into this |
131 | */ |
132 | free += global_page_state(NR_SLAB_RECLAIMABLE); |
133 | |
134 | /* |
135 | * Leave the last 3% for root |
136 | */ |
137 | if (!cap_sys_admin) |
138 | free -= free / 32; |
139 | |
140 | if (free > pages) |
141 | return 0; |
142 | |
143 | /* |
144 | * nr_free_pages() is very expensive on large systems, |
145 | * only call if we're about to fail. |
146 | */ |
147 | n = nr_free_pages(); |
148 | |
149 | /* |
150 | * Leave reserved pages. The pages are not for anonymous pages. |
151 | */ |
152 | if (n <= totalreserve_pages) |
153 | goto error; |
154 | else |
155 | n -= totalreserve_pages; |
156 | |
157 | /* |
158 | * Leave the last 3% for root |
159 | */ |
160 | if (!cap_sys_admin) |
161 | n -= n / 32; |
162 | free += n; |
163 | |
164 | if (free > pages) |
165 | return 0; |
166 | |
167 | goto error; |
168 | } |
169 | |
170 | allowed = (totalram_pages - hugetlb_total_pages()) |
171 | * sysctl_overcommit_ratio / 100; |
172 | /* |
173 | * Leave the last 3% for root |
174 | */ |
175 | if (!cap_sys_admin) |
176 | allowed -= allowed / 32; |
177 | allowed += total_swap_pages; |
178 | |
179 | /* Don't let a single process grow too big: |
180 | leave 3% of the size of this process for other processes */ |
181 | if (mm) |
182 | allowed -= mm->total_vm / 32; |
183 | |
184 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) |
185 | return 0; |
186 | error: |
187 | vm_unacct_memory(pages); |
188 | |
189 | return -ENOMEM; |
190 | } |
191 | |
192 | /* |
193 | * Requires inode->i_mapping->i_mmap_lock |
194 | */ |
195 | static void __remove_shared_vm_struct(struct vm_area_struct *vma, |
196 | struct file *file, struct address_space *mapping) |
197 | { |
198 | if (vma->vm_flags & VM_DENYWRITE) |
199 | atomic_inc(&file->f_path.dentry->d_inode->i_writecount); |
200 | if (vma->vm_flags & VM_SHARED) |
201 | mapping->i_mmap_writable--; |
202 | |
203 | flush_dcache_mmap_lock(mapping); |
204 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) |
205 | list_del_init(&vma->shared.vm_set.list); |
206 | else |
207 | vma_prio_tree_remove(vma, &mapping->i_mmap); |
208 | flush_dcache_mmap_unlock(mapping); |
209 | } |
210 | |
211 | /* |
212 | * Unlink a file-based vm structure from its prio_tree, to hide |
213 | * vma from rmap and vmtruncate before freeing its page tables. |
214 | */ |
215 | void unlink_file_vma(struct vm_area_struct *vma) |
216 | { |
217 | struct file *file = vma->vm_file; |
218 | |
219 | if (file) { |
220 | struct address_space *mapping = file->f_mapping; |
221 | spin_lock(&mapping->i_mmap_lock); |
222 | __remove_shared_vm_struct(vma, file, mapping); |
223 | spin_unlock(&mapping->i_mmap_lock); |
224 | } |
225 | } |
226 | |
227 | /* |
228 | * Close a vm structure and free it, returning the next. |
229 | */ |
230 | static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) |
231 | { |
232 | struct vm_area_struct *next = vma->vm_next; |
233 | |
234 | might_sleep(); |
235 | if (vma->vm_ops && vma->vm_ops->close) |
236 | vma->vm_ops->close(vma); |
237 | if (vma->vm_file) { |
238 | fput(vma->vm_file); |
239 | if (vma->vm_flags & VM_EXECUTABLE) |
240 | removed_exe_file_vma(vma->vm_mm); |
241 | } |
242 | mpol_put(vma_policy(vma)); |
243 | kmem_cache_free(vm_area_cachep, vma); |
244 | return next; |
245 | } |
246 | |
247 | SYSCALL_DEFINE1(brk, unsigned long, brk) |
248 | { |
249 | unsigned long rlim, retval; |
250 | unsigned long newbrk, oldbrk; |
251 | struct mm_struct *mm = current->mm; |
252 | unsigned long min_brk; |
253 | |
254 | down_write(&mm->mmap_sem); |
255 | |
256 | #ifdef CONFIG_COMPAT_BRK |
257 | /* |
258 | * CONFIG_COMPAT_BRK can still be overridden by setting |
259 | * randomize_va_space to 2, which will still cause mm->start_brk |
260 | * to be arbitrarily shifted |
261 | */ |
262 | if (mm->start_brk > PAGE_ALIGN(mm->end_data)) |
263 | min_brk = mm->start_brk; |
264 | else |
265 | min_brk = mm->end_data; |
266 | #else |
267 | min_brk = mm->start_brk; |
268 | #endif |
269 | if (brk < min_brk) |
270 | goto out; |
271 | |
272 | /* |
273 | * Check against rlimit here. If this check is done later after the test |
274 | * of oldbrk with newbrk then it can escape the test and let the data |
275 | * segment grow beyond its set limit the in case where the limit is |
276 | * not page aligned -Ram Gupta |
277 | */ |
278 | rlim = rlimit(RLIMIT_DATA); |
279 | if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + |
280 | (mm->end_data - mm->start_data) > rlim) |
281 | goto out; |
282 | |
283 | newbrk = PAGE_ALIGN(brk); |
284 | oldbrk = PAGE_ALIGN(mm->brk); |
285 | if (oldbrk == newbrk) |
286 | goto set_brk; |
287 | |
288 | /* Always allow shrinking brk. */ |
289 | if (brk <= mm->brk) { |
290 | if (!do_munmap(mm, newbrk, oldbrk-newbrk)) |
291 | goto set_brk; |
292 | goto out; |
293 | } |
294 | |
295 | /* Check against existing mmap mappings. */ |
296 | if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) |
297 | goto out; |
298 | |
299 | /* Ok, looks good - let it rip. */ |
300 | if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) |
301 | goto out; |
302 | set_brk: |
303 | mm->brk = brk; |
304 | out: |
305 | retval = mm->brk; |
306 | up_write(&mm->mmap_sem); |
307 | return retval; |
308 | } |
309 | |
310 | #ifdef DEBUG_MM_RB |
311 | static int browse_rb(struct rb_root *root) |
312 | { |
313 | int i = 0, j; |
314 | struct rb_node *nd, *pn = NULL; |
315 | unsigned long prev = 0, pend = 0; |
316 | |
317 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { |
318 | struct vm_area_struct *vma; |
319 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); |
320 | if (vma->vm_start < prev) |
321 | printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; |
322 | if (vma->vm_start < pend) |
323 | printk("vm_start %lx pend %lx\n", vma->vm_start, pend); |
324 | if (vma->vm_start > vma->vm_end) |
325 | printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); |
326 | i++; |
327 | pn = nd; |
328 | prev = vma->vm_start; |
329 | pend = vma->vm_end; |
330 | } |
331 | j = 0; |
332 | for (nd = pn; nd; nd = rb_prev(nd)) { |
333 | j++; |
334 | } |
335 | if (i != j) |
336 | printk("backwards %d, forwards %d\n", j, i), i = 0; |
337 | return i; |
338 | } |
339 | |
340 | void validate_mm(struct mm_struct *mm) |
341 | { |
342 | int bug = 0; |
343 | int i = 0; |
344 | struct vm_area_struct *tmp = mm->mmap; |
345 | while (tmp) { |
346 | tmp = tmp->vm_next; |
347 | i++; |
348 | } |
349 | if (i != mm->map_count) |
350 | printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; |
351 | i = browse_rb(&mm->mm_rb); |
352 | if (i != mm->map_count) |
353 | printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; |
354 | BUG_ON(bug); |
355 | } |
356 | #else |
357 | #define validate_mm(mm) do { } while (0) |
358 | #endif |
359 | |
360 | static struct vm_area_struct * |
361 | find_vma_prepare(struct mm_struct *mm, unsigned long addr, |
362 | struct vm_area_struct **pprev, struct rb_node ***rb_link, |
363 | struct rb_node ** rb_parent) |
364 | { |
365 | struct vm_area_struct * vma; |
366 | struct rb_node ** __rb_link, * __rb_parent, * rb_prev; |
367 | |
368 | __rb_link = &mm->mm_rb.rb_node; |
369 | rb_prev = __rb_parent = NULL; |
370 | vma = NULL; |
371 | |
372 | while (*__rb_link) { |
373 | struct vm_area_struct *vma_tmp; |
374 | |
375 | __rb_parent = *__rb_link; |
376 | vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); |
377 | |
378 | if (vma_tmp->vm_end > addr) { |
379 | vma = vma_tmp; |
380 | if (vma_tmp->vm_start <= addr) |
381 | break; |
382 | __rb_link = &__rb_parent->rb_left; |
383 | } else { |
384 | rb_prev = __rb_parent; |
385 | __rb_link = &__rb_parent->rb_right; |
386 | } |
387 | } |
388 | |
389 | *pprev = NULL; |
390 | if (rb_prev) |
391 | *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); |
392 | *rb_link = __rb_link; |
393 | *rb_parent = __rb_parent; |
394 | return vma; |
395 | } |
396 | |
397 | static inline void |
398 | __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, |
399 | struct vm_area_struct *prev, struct rb_node *rb_parent) |
400 | { |
401 | struct vm_area_struct *next; |
402 | |
403 | vma->vm_prev = prev; |
404 | if (prev) { |
405 | next = prev->vm_next; |
406 | prev->vm_next = vma; |
407 | } else { |
408 | mm->mmap = vma; |
409 | if (rb_parent) |
410 | next = rb_entry(rb_parent, |
411 | struct vm_area_struct, vm_rb); |
412 | else |
413 | next = NULL; |
414 | } |
415 | vma->vm_next = next; |
416 | if (next) |
417 | next->vm_prev = vma; |
418 | } |
419 | |
420 | void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, |
421 | struct rb_node **rb_link, struct rb_node *rb_parent) |
422 | { |
423 | rb_link_node(&vma->vm_rb, rb_parent, rb_link); |
424 | rb_insert_color(&vma->vm_rb, &mm->mm_rb); |
425 | } |
426 | |
427 | static void __vma_link_file(struct vm_area_struct *vma) |
428 | { |
429 | struct file *file; |
430 | |
431 | file = vma->vm_file; |
432 | if (file) { |
433 | struct address_space *mapping = file->f_mapping; |
434 | |
435 | if (vma->vm_flags & VM_DENYWRITE) |
436 | atomic_dec(&file->f_path.dentry->d_inode->i_writecount); |
437 | if (vma->vm_flags & VM_SHARED) |
438 | mapping->i_mmap_writable++; |
439 | |
440 | flush_dcache_mmap_lock(mapping); |
441 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) |
442 | vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); |
443 | else |
444 | vma_prio_tree_insert(vma, &mapping->i_mmap); |
445 | flush_dcache_mmap_unlock(mapping); |
446 | } |
447 | } |
448 | |
449 | static void |
450 | __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, |
451 | struct vm_area_struct *prev, struct rb_node **rb_link, |
452 | struct rb_node *rb_parent) |
453 | { |
454 | __vma_link_list(mm, vma, prev, rb_parent); |
455 | __vma_link_rb(mm, vma, rb_link, rb_parent); |
456 | } |
457 | |
458 | static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, |
459 | struct vm_area_struct *prev, struct rb_node **rb_link, |
460 | struct rb_node *rb_parent) |
461 | { |
462 | struct address_space *mapping = NULL; |
463 | |
464 | if (vma->vm_file) |
465 | mapping = vma->vm_file->f_mapping; |
466 | |
467 | if (mapping) { |
468 | spin_lock(&mapping->i_mmap_lock); |
469 | vma->vm_truncate_count = mapping->truncate_count; |
470 | } |
471 | |
472 | __vma_link(mm, vma, prev, rb_link, rb_parent); |
473 | __vma_link_file(vma); |
474 | |
475 | if (mapping) |
476 | spin_unlock(&mapping->i_mmap_lock); |
477 | |
478 | mm->map_count++; |
479 | validate_mm(mm); |
480 | } |
481 | |
482 | /* |
483 | * Helper for vma_adjust in the split_vma insert case: |
484 | * insert vm structure into list and rbtree and anon_vma, |
485 | * but it has already been inserted into prio_tree earlier. |
486 | */ |
487 | static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) |
488 | { |
489 | struct vm_area_struct *__vma, *prev; |
490 | struct rb_node **rb_link, *rb_parent; |
491 | |
492 | __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); |
493 | BUG_ON(__vma && __vma->vm_start < vma->vm_end); |
494 | __vma_link(mm, vma, prev, rb_link, rb_parent); |
495 | mm->map_count++; |
496 | } |
497 | |
498 | static inline void |
499 | __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, |
500 | struct vm_area_struct *prev) |
501 | { |
502 | struct vm_area_struct *next = vma->vm_next; |
503 | |
504 | prev->vm_next = next; |
505 | if (next) |
506 | next->vm_prev = prev; |
507 | rb_erase(&vma->vm_rb, &mm->mm_rb); |
508 | if (mm->mmap_cache == vma) |
509 | mm->mmap_cache = prev; |
510 | } |
511 | |
512 | /* |
513 | * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that |
514 | * is already present in an i_mmap tree without adjusting the tree. |
515 | * The following helper function should be used when such adjustments |
516 | * are necessary. The "insert" vma (if any) is to be inserted |
517 | * before we drop the necessary locks. |
518 | */ |
519 | int vma_adjust(struct vm_area_struct *vma, unsigned long start, |
520 | unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) |
521 | { |
522 | struct mm_struct *mm = vma->vm_mm; |
523 | struct vm_area_struct *next = vma->vm_next; |
524 | struct vm_area_struct *importer = NULL; |
525 | struct address_space *mapping = NULL; |
526 | struct prio_tree_root *root = NULL; |
527 | struct anon_vma *anon_vma = NULL; |
528 | struct file *file = vma->vm_file; |
529 | long adjust_next = 0; |
530 | int remove_next = 0; |
531 | |
532 | if (next && !insert) { |
533 | struct vm_area_struct *exporter = NULL; |
534 | |
535 | if (end >= next->vm_end) { |
536 | /* |
537 | * vma expands, overlapping all the next, and |
538 | * perhaps the one after too (mprotect case 6). |
539 | */ |
540 | again: remove_next = 1 + (end > next->vm_end); |
541 | end = next->vm_end; |
542 | exporter = next; |
543 | importer = vma; |
544 | } else if (end > next->vm_start) { |
545 | /* |
546 | * vma expands, overlapping part of the next: |
547 | * mprotect case 5 shifting the boundary up. |
548 | */ |
549 | adjust_next = (end - next->vm_start) >> PAGE_SHIFT; |
550 | exporter = next; |
551 | importer = vma; |
552 | } else if (end < vma->vm_end) { |
553 | /* |
554 | * vma shrinks, and !insert tells it's not |
555 | * split_vma inserting another: so it must be |
556 | * mprotect case 4 shifting the boundary down. |
557 | */ |
558 | adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); |
559 | exporter = vma; |
560 | importer = next; |
561 | } |
562 | |
563 | /* |
564 | * Easily overlooked: when mprotect shifts the boundary, |
565 | * make sure the expanding vma has anon_vma set if the |
566 | * shrinking vma had, to cover any anon pages imported. |
567 | */ |
568 | if (exporter && exporter->anon_vma && !importer->anon_vma) { |
569 | if (anon_vma_clone(importer, exporter)) |
570 | return -ENOMEM; |
571 | importer->anon_vma = exporter->anon_vma; |
572 | } |
573 | } |
574 | |
575 | if (file) { |
576 | mapping = file->f_mapping; |
577 | if (!(vma->vm_flags & VM_NONLINEAR)) |
578 | root = &mapping->i_mmap; |
579 | spin_lock(&mapping->i_mmap_lock); |
580 | if (importer && |
581 | vma->vm_truncate_count != next->vm_truncate_count) { |
582 | /* |
583 | * unmap_mapping_range might be in progress: |
584 | * ensure that the expanding vma is rescanned. |
585 | */ |
586 | importer->vm_truncate_count = 0; |
587 | } |
588 | if (insert) { |
589 | insert->vm_truncate_count = vma->vm_truncate_count; |
590 | /* |
591 | * Put into prio_tree now, so instantiated pages |
592 | * are visible to arm/parisc __flush_dcache_page |
593 | * throughout; but we cannot insert into address |
594 | * space until vma start or end is updated. |
595 | */ |
596 | __vma_link_file(insert); |
597 | } |
598 | } |
599 | |
600 | vma_adjust_trans_huge(vma, start, end, adjust_next); |
601 | |
602 | /* |
603 | * When changing only vma->vm_end, we don't really need anon_vma |
604 | * lock. This is a fairly rare case by itself, but the anon_vma |
605 | * lock may be shared between many sibling processes. Skipping |
606 | * the lock for brk adjustments makes a difference sometimes. |
607 | */ |
608 | if (vma->anon_vma && (insert || importer || start != vma->vm_start)) { |
609 | anon_vma = vma->anon_vma; |
610 | anon_vma_lock(anon_vma); |
611 | } |
612 | |
613 | if (root) { |
614 | flush_dcache_mmap_lock(mapping); |
615 | vma_prio_tree_remove(vma, root); |
616 | if (adjust_next) |
617 | vma_prio_tree_remove(next, root); |
618 | } |
619 | |
620 | vma->vm_start = start; |
621 | vma->vm_end = end; |
622 | vma->vm_pgoff = pgoff; |
623 | if (adjust_next) { |
624 | next->vm_start += adjust_next << PAGE_SHIFT; |
625 | next->vm_pgoff += adjust_next; |
626 | } |
627 | |
628 | if (root) { |
629 | if (adjust_next) |
630 | vma_prio_tree_insert(next, root); |
631 | vma_prio_tree_insert(vma, root); |
632 | flush_dcache_mmap_unlock(mapping); |
633 | } |
634 | |
635 | if (remove_next) { |
636 | /* |
637 | * vma_merge has merged next into vma, and needs |
638 | * us to remove next before dropping the locks. |
639 | */ |
640 | __vma_unlink(mm, next, vma); |
641 | if (file) |
642 | __remove_shared_vm_struct(next, file, mapping); |
643 | } else if (insert) { |
644 | /* |
645 | * split_vma has split insert from vma, and needs |
646 | * us to insert it before dropping the locks |
647 | * (it may either follow vma or precede it). |
648 | */ |
649 | __insert_vm_struct(mm, insert); |
650 | } |
651 | |
652 | if (anon_vma) |
653 | anon_vma_unlock(anon_vma); |
654 | if (mapping) |
655 | spin_unlock(&mapping->i_mmap_lock); |
656 | |
657 | if (remove_next) { |
658 | if (file) { |
659 | fput(file); |
660 | if (next->vm_flags & VM_EXECUTABLE) |
661 | removed_exe_file_vma(mm); |
662 | } |
663 | if (next->anon_vma) |
664 | anon_vma_merge(vma, next); |
665 | mm->map_count--; |
666 | mpol_put(vma_policy(next)); |
667 | kmem_cache_free(vm_area_cachep, next); |
668 | /* |
669 | * In mprotect's case 6 (see comments on vma_merge), |
670 | * we must remove another next too. It would clutter |
671 | * up the code too much to do both in one go. |
672 | */ |
673 | if (remove_next == 2) { |
674 | next = vma->vm_next; |
675 | goto again; |
676 | } |
677 | } |
678 | |
679 | validate_mm(mm); |
680 | |
681 | return 0; |
682 | } |
683 | |
684 | /* |
685 | * If the vma has a ->close operation then the driver probably needs to release |
686 | * per-vma resources, so we don't attempt to merge those. |
687 | */ |
688 | static inline int is_mergeable_vma(struct vm_area_struct *vma, |
689 | struct file *file, unsigned long vm_flags) |
690 | { |
691 | /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */ |
692 | if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR) |
693 | return 0; |
694 | if (vma->vm_file != file) |
695 | return 0; |
696 | if (vma->vm_ops && vma->vm_ops->close) |
697 | return 0; |
698 | return 1; |
699 | } |
700 | |
701 | static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, |
702 | struct anon_vma *anon_vma2) |
703 | { |
704 | return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); |
705 | } |
706 | |
707 | /* |
708 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
709 | * in front of (at a lower virtual address and file offset than) the vma. |
710 | * |
711 | * We cannot merge two vmas if they have differently assigned (non-NULL) |
712 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
713 | * |
714 | * We don't check here for the merged mmap wrapping around the end of pagecache |
715 | * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which |
716 | * wrap, nor mmaps which cover the final page at index -1UL. |
717 | */ |
718 | static int |
719 | can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, |
720 | struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) |
721 | { |
722 | if (is_mergeable_vma(vma, file, vm_flags) && |
723 | is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { |
724 | if (vma->vm_pgoff == vm_pgoff) |
725 | return 1; |
726 | } |
727 | return 0; |
728 | } |
729 | |
730 | /* |
731 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) |
732 | * beyond (at a higher virtual address and file offset than) the vma. |
733 | * |
734 | * We cannot merge two vmas if they have differently assigned (non-NULL) |
735 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. |
736 | */ |
737 | static int |
738 | can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, |
739 | struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) |
740 | { |
741 | if (is_mergeable_vma(vma, file, vm_flags) && |
742 | is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { |
743 | pgoff_t vm_pglen; |
744 | vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; |
745 | if (vma->vm_pgoff + vm_pglen == vm_pgoff) |
746 | return 1; |
747 | } |
748 | return 0; |
749 | } |
750 | |
751 | /* |
752 | * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out |
753 | * whether that can be merged with its predecessor or its successor. |
754 | * Or both (it neatly fills a hole). |
755 | * |
756 | * In most cases - when called for mmap, brk or mremap - [addr,end) is |
757 | * certain not to be mapped by the time vma_merge is called; but when |
758 | * called for mprotect, it is certain to be already mapped (either at |
759 | * an offset within prev, or at the start of next), and the flags of |
760 | * this area are about to be changed to vm_flags - and the no-change |
761 | * case has already been eliminated. |
762 | * |
763 | * The following mprotect cases have to be considered, where AAAA is |
764 | * the area passed down from mprotect_fixup, never extending beyond one |
765 | * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: |
766 | * |
767 | * AAAA AAAA AAAA AAAA |
768 | * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX |
769 | * cannot merge might become might become might become |
770 | * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or |
771 | * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or |
772 | * mremap move: PPPPNNNNNNNN 8 |
773 | * AAAA |
774 | * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN |
775 | * might become case 1 below case 2 below case 3 below |
776 | * |
777 | * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: |
778 | * mprotect_fixup updates vm_flags & vm_page_prot on successful return. |
779 | */ |
780 | struct vm_area_struct *vma_merge(struct mm_struct *mm, |
781 | struct vm_area_struct *prev, unsigned long addr, |
782 | unsigned long end, unsigned long vm_flags, |
783 | struct anon_vma *anon_vma, struct file *file, |
784 | pgoff_t pgoff, struct mempolicy *policy) |
785 | { |
786 | pgoff_t pglen = (end - addr) >> PAGE_SHIFT; |
787 | struct vm_area_struct *area, *next; |
788 | int err; |
789 | |
790 | /* |
791 | * We later require that vma->vm_flags == vm_flags, |
792 | * so this tests vma->vm_flags & VM_SPECIAL, too. |
793 | */ |
794 | if (vm_flags & VM_SPECIAL) |
795 | return NULL; |
796 | |
797 | if (prev) |
798 | next = prev->vm_next; |
799 | else |
800 | next = mm->mmap; |
801 | area = next; |
802 | if (next && next->vm_end == end) /* cases 6, 7, 8 */ |
803 | next = next->vm_next; |
804 | |
805 | /* |
806 | * Can it merge with the predecessor? |
807 | */ |
808 | if (prev && prev->vm_end == addr && |
809 | mpol_equal(vma_policy(prev), policy) && |
810 | can_vma_merge_after(prev, vm_flags, |
811 | anon_vma, file, pgoff)) { |
812 | /* |
813 | * OK, it can. Can we now merge in the successor as well? |
814 | */ |
815 | if (next && end == next->vm_start && |
816 | mpol_equal(policy, vma_policy(next)) && |
817 | can_vma_merge_before(next, vm_flags, |
818 | anon_vma, file, pgoff+pglen) && |
819 | is_mergeable_anon_vma(prev->anon_vma, |
820 | next->anon_vma)) { |
821 | /* cases 1, 6 */ |
822 | err = vma_adjust(prev, prev->vm_start, |
823 | next->vm_end, prev->vm_pgoff, NULL); |
824 | } else /* cases 2, 5, 7 */ |
825 | err = vma_adjust(prev, prev->vm_start, |
826 | end, prev->vm_pgoff, NULL); |
827 | if (err) |
828 | return NULL; |
829 | khugepaged_enter_vma_merge(prev); |
830 | return prev; |
831 | } |
832 | |
833 | /* |
834 | * Can this new request be merged in front of next? |
835 | */ |
836 | if (next && end == next->vm_start && |
837 | mpol_equal(policy, vma_policy(next)) && |
838 | can_vma_merge_before(next, vm_flags, |
839 | anon_vma, file, pgoff+pglen)) { |
840 | if (prev && addr < prev->vm_end) /* case 4 */ |
841 | err = vma_adjust(prev, prev->vm_start, |
842 | addr, prev->vm_pgoff, NULL); |
843 | else /* cases 3, 8 */ |
844 | err = vma_adjust(area, addr, next->vm_end, |
845 | next->vm_pgoff - pglen, NULL); |
846 | if (err) |
847 | return NULL; |
848 | khugepaged_enter_vma_merge(area); |
849 | return area; |
850 | } |
851 | |
852 | return NULL; |
853 | } |
854 | |
855 | /* |
856 | * Rough compatbility check to quickly see if it's even worth looking |
857 | * at sharing an anon_vma. |
858 | * |
859 | * They need to have the same vm_file, and the flags can only differ |
860 | * in things that mprotect may change. |
861 | * |
862 | * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that |
863 | * we can merge the two vma's. For example, we refuse to merge a vma if |
864 | * there is a vm_ops->close() function, because that indicates that the |
865 | * driver is doing some kind of reference counting. But that doesn't |
866 | * really matter for the anon_vma sharing case. |
867 | */ |
868 | static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) |
869 | { |
870 | return a->vm_end == b->vm_start && |
871 | mpol_equal(vma_policy(a), vma_policy(b)) && |
872 | a->vm_file == b->vm_file && |
873 | !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) && |
874 | b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); |
875 | } |
876 | |
877 | /* |
878 | * Do some basic sanity checking to see if we can re-use the anon_vma |
879 | * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be |
880 | * the same as 'old', the other will be the new one that is trying |
881 | * to share the anon_vma. |
882 | * |
883 | * NOTE! This runs with mm_sem held for reading, so it is possible that |
884 | * the anon_vma of 'old' is concurrently in the process of being set up |
885 | * by another page fault trying to merge _that_. But that's ok: if it |
886 | * is being set up, that automatically means that it will be a singleton |
887 | * acceptable for merging, so we can do all of this optimistically. But |
888 | * we do that ACCESS_ONCE() to make sure that we never re-load the pointer. |
889 | * |
890 | * IOW: that the "list_is_singular()" test on the anon_vma_chain only |
891 | * matters for the 'stable anon_vma' case (ie the thing we want to avoid |
892 | * is to return an anon_vma that is "complex" due to having gone through |
893 | * a fork). |
894 | * |
895 | * We also make sure that the two vma's are compatible (adjacent, |
896 | * and with the same memory policies). That's all stable, even with just |
897 | * a read lock on the mm_sem. |
898 | */ |
899 | static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) |
900 | { |
901 | if (anon_vma_compatible(a, b)) { |
902 | struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma); |
903 | |
904 | if (anon_vma && list_is_singular(&old->anon_vma_chain)) |
905 | return anon_vma; |
906 | } |
907 | return NULL; |
908 | } |
909 | |
910 | /* |
911 | * find_mergeable_anon_vma is used by anon_vma_prepare, to check |
912 | * neighbouring vmas for a suitable anon_vma, before it goes off |
913 | * to allocate a new anon_vma. It checks because a repetitive |
914 | * sequence of mprotects and faults may otherwise lead to distinct |
915 | * anon_vmas being allocated, preventing vma merge in subsequent |
916 | * mprotect. |
917 | */ |
918 | struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) |
919 | { |
920 | struct anon_vma *anon_vma; |
921 | struct vm_area_struct *near; |
922 | |
923 | near = vma->vm_next; |
924 | if (!near) |
925 | goto try_prev; |
926 | |
927 | anon_vma = reusable_anon_vma(near, vma, near); |
928 | if (anon_vma) |
929 | return anon_vma; |
930 | try_prev: |
931 | /* |
932 | * It is potentially slow to have to call find_vma_prev here. |
933 | * But it's only on the first write fault on the vma, not |
934 | * every time, and we could devise a way to avoid it later |
935 | * (e.g. stash info in next's anon_vma_node when assigning |
936 | * an anon_vma, or when trying vma_merge). Another time. |
937 | */ |
938 | BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); |
939 | if (!near) |
940 | goto none; |
941 | |
942 | anon_vma = reusable_anon_vma(near, near, vma); |
943 | if (anon_vma) |
944 | return anon_vma; |
945 | none: |
946 | /* |
947 | * There's no absolute need to look only at touching neighbours: |
948 | * we could search further afield for "compatible" anon_vmas. |
949 | * But it would probably just be a waste of time searching, |
950 | * or lead to too many vmas hanging off the same anon_vma. |
951 | * We're trying to allow mprotect remerging later on, |
952 | * not trying to minimize memory used for anon_vmas. |
953 | */ |
954 | return NULL; |
955 | } |
956 | |
957 | #ifdef CONFIG_PROC_FS |
958 | void vm_stat_account(struct mm_struct *mm, unsigned long flags, |
959 | struct file *file, long pages) |
960 | { |
961 | const unsigned long stack_flags |
962 | = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); |
963 | |
964 | if (file) { |
965 | mm->shared_vm += pages; |
966 | if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) |
967 | mm->exec_vm += pages; |
968 | } else if (flags & stack_flags) |
969 | mm->stack_vm += pages; |
970 | if (flags & (VM_RESERVED|VM_IO)) |
971 | mm->reserved_vm += pages; |
972 | } |
973 | #endif /* CONFIG_PROC_FS */ |
974 | |
975 | /* |
976 | * The caller must hold down_write(¤t->mm->mmap_sem). |
977 | */ |
978 | |
979 | unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, |
980 | unsigned long len, unsigned long prot, |
981 | unsigned long flags, unsigned long pgoff) |
982 | { |
983 | struct mm_struct * mm = current->mm; |
984 | struct inode *inode; |
985 | unsigned int vm_flags; |
986 | int error; |
987 | unsigned long reqprot = prot; |
988 | |
989 | /* |
990 | * Does the application expect PROT_READ to imply PROT_EXEC? |
991 | * |
992 | * (the exception is when the underlying filesystem is noexec |
993 | * mounted, in which case we dont add PROT_EXEC.) |
994 | */ |
995 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
996 | if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) |
997 | prot |= PROT_EXEC; |
998 | |
999 | if (!len) |
1000 | return -EINVAL; |
1001 | |
1002 | if (!(flags & MAP_FIXED)) |
1003 | addr = round_hint_to_min(addr); |
1004 | |
1005 | /* Careful about overflows.. */ |
1006 | len = PAGE_ALIGN(len); |
1007 | if (!len) |
1008 | return -ENOMEM; |
1009 | |
1010 | /* offset overflow? */ |
1011 | if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) |
1012 | return -EOVERFLOW; |
1013 | |
1014 | /* Too many mappings? */ |
1015 | if (mm->map_count > sysctl_max_map_count) |
1016 | return -ENOMEM; |
1017 | |
1018 | /* Obtain the address to map to. we verify (or select) it and ensure |
1019 | * that it represents a valid section of the address space. |
1020 | */ |
1021 | addr = get_unmapped_area(file, addr, len, pgoff, flags); |
1022 | if (addr & ~PAGE_MASK) |
1023 | return addr; |
1024 | |
1025 | /* Do simple checking here so the lower-level routines won't have |
1026 | * to. we assume access permissions have been handled by the open |
1027 | * of the memory object, so we don't do any here. |
1028 | */ |
1029 | vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | |
1030 | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
1031 | |
1032 | if (flags & MAP_LOCKED) |
1033 | if (!can_do_mlock()) |
1034 | return -EPERM; |
1035 | |
1036 | /* mlock MCL_FUTURE? */ |
1037 | if (vm_flags & VM_LOCKED) { |
1038 | unsigned long locked, lock_limit; |
1039 | locked = len >> PAGE_SHIFT; |
1040 | locked += mm->locked_vm; |
1041 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
1042 | lock_limit >>= PAGE_SHIFT; |
1043 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
1044 | return -EAGAIN; |
1045 | } |
1046 | |
1047 | inode = file ? file->f_path.dentry->d_inode : NULL; |
1048 | |
1049 | if (file) { |
1050 | switch (flags & MAP_TYPE) { |
1051 | case MAP_SHARED: |
1052 | if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) |
1053 | return -EACCES; |
1054 | |
1055 | /* |
1056 | * Make sure we don't allow writing to an append-only |
1057 | * file.. |
1058 | */ |
1059 | if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) |
1060 | return -EACCES; |
1061 | |
1062 | /* |
1063 | * Make sure there are no mandatory locks on the file. |
1064 | */ |
1065 | if (locks_verify_locked(inode)) |
1066 | return -EAGAIN; |
1067 | |
1068 | vm_flags |= VM_SHARED | VM_MAYSHARE; |
1069 | if (!(file->f_mode & FMODE_WRITE)) |
1070 | vm_flags &= ~(VM_MAYWRITE | VM_SHARED); |
1071 | |
1072 | /* fall through */ |
1073 | case MAP_PRIVATE: |
1074 | if (!(file->f_mode & FMODE_READ)) |
1075 | return -EACCES; |
1076 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { |
1077 | if (vm_flags & VM_EXEC) |
1078 | return -EPERM; |
1079 | vm_flags &= ~VM_MAYEXEC; |
1080 | } |
1081 | |
1082 | if (!file->f_op || !file->f_op->mmap) |
1083 | return -ENODEV; |
1084 | break; |
1085 | |
1086 | default: |
1087 | return -EINVAL; |
1088 | } |
1089 | } else { |
1090 | switch (flags & MAP_TYPE) { |
1091 | case MAP_SHARED: |
1092 | /* |
1093 | * Ignore pgoff. |
1094 | */ |
1095 | pgoff = 0; |
1096 | vm_flags |= VM_SHARED | VM_MAYSHARE; |
1097 | break; |
1098 | case MAP_PRIVATE: |
1099 | /* |
1100 | * Set pgoff according to addr for anon_vma. |
1101 | */ |
1102 | pgoff = addr >> PAGE_SHIFT; |
1103 | break; |
1104 | default: |
1105 | return -EINVAL; |
1106 | } |
1107 | } |
1108 | |
1109 | error = security_file_mmap(file, reqprot, prot, flags, addr, 0); |
1110 | if (error) |
1111 | return error; |
1112 | |
1113 | return mmap_region(file, addr, len, flags, vm_flags, pgoff); |
1114 | } |
1115 | EXPORT_SYMBOL(do_mmap_pgoff); |
1116 | |
1117 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
1118 | unsigned long, prot, unsigned long, flags, |
1119 | unsigned long, fd, unsigned long, pgoff) |
1120 | { |
1121 | struct file *file = NULL; |
1122 | unsigned long retval = -EBADF; |
1123 | |
1124 | if (!(flags & MAP_ANONYMOUS)) { |
1125 | audit_mmap_fd(fd, flags); |
1126 | if (unlikely(flags & MAP_HUGETLB)) |
1127 | return -EINVAL; |
1128 | file = fget(fd); |
1129 | if (!file) |
1130 | goto out; |
1131 | } else if (flags & MAP_HUGETLB) { |
1132 | struct user_struct *user = NULL; |
1133 | /* |
1134 | * VM_NORESERVE is used because the reservations will be |
1135 | * taken when vm_ops->mmap() is called |
1136 | * A dummy user value is used because we are not locking |
1137 | * memory so no accounting is necessary |
1138 | */ |
1139 | len = ALIGN(len, huge_page_size(&default_hstate)); |
1140 | file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE, |
1141 | &user, HUGETLB_ANONHUGE_INODE); |
1142 | if (IS_ERR(file)) |
1143 | return PTR_ERR(file); |
1144 | } |
1145 | |
1146 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); |
1147 | |
1148 | down_write(¤t->mm->mmap_sem); |
1149 | retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
1150 | up_write(¤t->mm->mmap_sem); |
1151 | |
1152 | if (file) |
1153 | fput(file); |
1154 | out: |
1155 | return retval; |
1156 | } |
1157 | |
1158 | #ifdef __ARCH_WANT_SYS_OLD_MMAP |
1159 | struct mmap_arg_struct { |
1160 | unsigned long addr; |
1161 | unsigned long len; |
1162 | unsigned long prot; |
1163 | unsigned long flags; |
1164 | unsigned long fd; |
1165 | unsigned long offset; |
1166 | }; |
1167 | |
1168 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
1169 | { |
1170 | struct mmap_arg_struct a; |
1171 | |
1172 | if (copy_from_user(&a, arg, sizeof(a))) |
1173 | return -EFAULT; |
1174 | if (a.offset & ~PAGE_MASK) |
1175 | return -EINVAL; |
1176 | |
1177 | return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
1178 | a.offset >> PAGE_SHIFT); |
1179 | } |
1180 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
1181 | |
1182 | /* |
1183 | * Some shared mappigns will want the pages marked read-only |
1184 | * to track write events. If so, we'll downgrade vm_page_prot |
1185 | * to the private version (using protection_map[] without the |
1186 | * VM_SHARED bit). |
1187 | */ |
1188 | int vma_wants_writenotify(struct vm_area_struct *vma) |
1189 | { |
1190 | unsigned int vm_flags = vma->vm_flags; |
1191 | |
1192 | /* If it was private or non-writable, the write bit is already clear */ |
1193 | if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) |
1194 | return 0; |
1195 | |
1196 | /* The backer wishes to know when pages are first written to? */ |
1197 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) |
1198 | return 1; |
1199 | |
1200 | /* The open routine did something to the protections already? */ |
1201 | if (pgprot_val(vma->vm_page_prot) != |
1202 | pgprot_val(vm_get_page_prot(vm_flags))) |
1203 | return 0; |
1204 | |
1205 | /* Specialty mapping? */ |
1206 | if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) |
1207 | return 0; |
1208 | |
1209 | /* Can the mapping track the dirty pages? */ |
1210 | return vma->vm_file && vma->vm_file->f_mapping && |
1211 | mapping_cap_account_dirty(vma->vm_file->f_mapping); |
1212 | } |
1213 | |
1214 | /* |
1215 | * We account for memory if it's a private writeable mapping, |
1216 | * not hugepages and VM_NORESERVE wasn't set. |
1217 | */ |
1218 | static inline int accountable_mapping(struct file *file, unsigned int vm_flags) |
1219 | { |
1220 | /* |
1221 | * hugetlb has its own accounting separate from the core VM |
1222 | * VM_HUGETLB may not be set yet so we cannot check for that flag. |
1223 | */ |
1224 | if (file && is_file_hugepages(file)) |
1225 | return 0; |
1226 | |
1227 | return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; |
1228 | } |
1229 | |
1230 | unsigned long mmap_region(struct file *file, unsigned long addr, |
1231 | unsigned long len, unsigned long flags, |
1232 | unsigned int vm_flags, unsigned long pgoff) |
1233 | { |
1234 | struct mm_struct *mm = current->mm; |
1235 | struct vm_area_struct *vma, *prev; |
1236 | int correct_wcount = 0; |
1237 | int error; |
1238 | struct rb_node **rb_link, *rb_parent; |
1239 | unsigned long charged = 0; |
1240 | struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; |
1241 | |
1242 | /* Clear old maps */ |
1243 | error = -ENOMEM; |
1244 | munmap_back: |
1245 | vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); |
1246 | if (vma && vma->vm_start < addr + len) { |
1247 | if (do_munmap(mm, addr, len)) |
1248 | return -ENOMEM; |
1249 | goto munmap_back; |
1250 | } |
1251 | |
1252 | /* Check against address space limit. */ |
1253 | if (!may_expand_vm(mm, len >> PAGE_SHIFT)) |
1254 | return -ENOMEM; |
1255 | |
1256 | /* |
1257 | * Set 'VM_NORESERVE' if we should not account for the |
1258 | * memory use of this mapping. |
1259 | */ |
1260 | if ((flags & MAP_NORESERVE)) { |
1261 | /* We honor MAP_NORESERVE if allowed to overcommit */ |
1262 | if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) |
1263 | vm_flags |= VM_NORESERVE; |
1264 | |
1265 | /* hugetlb applies strict overcommit unless MAP_NORESERVE */ |
1266 | if (file && is_file_hugepages(file)) |
1267 | vm_flags |= VM_NORESERVE; |
1268 | } |
1269 | |
1270 | /* |
1271 | * Private writable mapping: check memory availability |
1272 | */ |
1273 | if (accountable_mapping(file, vm_flags)) { |
1274 | charged = len >> PAGE_SHIFT; |
1275 | if (security_vm_enough_memory(charged)) |
1276 | return -ENOMEM; |
1277 | vm_flags |= VM_ACCOUNT; |
1278 | } |
1279 | |
1280 | /* |
1281 | * Can we just expand an old mapping? |
1282 | */ |
1283 | vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); |
1284 | if (vma) |
1285 | goto out; |
1286 | |
1287 | /* |
1288 | * Determine the object being mapped and call the appropriate |
1289 | * specific mapper. the address has already been validated, but |
1290 | * not unmapped, but the maps are removed from the list. |
1291 | */ |
1292 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
1293 | if (!vma) { |
1294 | error = -ENOMEM; |
1295 | goto unacct_error; |
1296 | } |
1297 | |
1298 | vma->vm_mm = mm; |
1299 | vma->vm_start = addr; |
1300 | vma->vm_end = addr + len; |
1301 | vma->vm_flags = vm_flags; |
1302 | vma->vm_page_prot = vm_get_page_prot(vm_flags); |
1303 | vma->vm_pgoff = pgoff; |
1304 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
1305 | |
1306 | if (file) { |
1307 | error = -EINVAL; |
1308 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) |
1309 | goto free_vma; |
1310 | if (vm_flags & VM_DENYWRITE) { |
1311 | error = deny_write_access(file); |
1312 | if (error) |
1313 | goto free_vma; |
1314 | correct_wcount = 1; |
1315 | } |
1316 | vma->vm_file = file; |
1317 | get_file(file); |
1318 | error = file->f_op->mmap(file, vma); |
1319 | if (error) |
1320 | goto unmap_and_free_vma; |
1321 | if (vm_flags & VM_EXECUTABLE) |
1322 | added_exe_file_vma(mm); |
1323 | |
1324 | /* Can addr have changed?? |
1325 | * |
1326 | * Answer: Yes, several device drivers can do it in their |
1327 | * f_op->mmap method. -DaveM |
1328 | */ |
1329 | addr = vma->vm_start; |
1330 | pgoff = vma->vm_pgoff; |
1331 | vm_flags = vma->vm_flags; |
1332 | } else if (vm_flags & VM_SHARED) { |
1333 | error = shmem_zero_setup(vma); |
1334 | if (error) |
1335 | goto free_vma; |
1336 | } |
1337 | |
1338 | if (vma_wants_writenotify(vma)) { |
1339 | pgprot_t pprot = vma->vm_page_prot; |
1340 | |
1341 | /* Can vma->vm_page_prot have changed?? |
1342 | * |
1343 | * Answer: Yes, drivers may have changed it in their |
1344 | * f_op->mmap method. |
1345 | * |
1346 | * Ensures that vmas marked as uncached stay that way. |
1347 | */ |
1348 | vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); |
1349 | if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot))) |
1350 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); |
1351 | } |
1352 | |
1353 | vma_link(mm, vma, prev, rb_link, rb_parent); |
1354 | file = vma->vm_file; |
1355 | |
1356 | /* Once vma denies write, undo our temporary denial count */ |
1357 | if (correct_wcount) |
1358 | atomic_inc(&inode->i_writecount); |
1359 | out: |
1360 | perf_event_mmap(vma); |
1361 | |
1362 | mm->total_vm += len >> PAGE_SHIFT; |
1363 | vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); |
1364 | if (vm_flags & VM_LOCKED) { |
1365 | if (!mlock_vma_pages_range(vma, addr, addr + len)) |
1366 | mm->locked_vm += (len >> PAGE_SHIFT); |
1367 | } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) |
1368 | make_pages_present(addr, addr + len); |
1369 | return addr; |
1370 | |
1371 | unmap_and_free_vma: |
1372 | if (correct_wcount) |
1373 | atomic_inc(&inode->i_writecount); |
1374 | vma->vm_file = NULL; |
1375 | fput(file); |
1376 | |
1377 | /* Undo any partial mapping done by a device driver. */ |
1378 | unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); |
1379 | charged = 0; |
1380 | free_vma: |
1381 | kmem_cache_free(vm_area_cachep, vma); |
1382 | unacct_error: |
1383 | if (charged) |
1384 | vm_unacct_memory(charged); |
1385 | return error; |
1386 | } |
1387 | |
1388 | /* Get an address range which is currently unmapped. |
1389 | * For shmat() with addr=0. |
1390 | * |
1391 | * Ugly calling convention alert: |
1392 | * Return value with the low bits set means error value, |
1393 | * ie |
1394 | * if (ret & ~PAGE_MASK) |
1395 | * error = ret; |
1396 | * |
1397 | * This function "knows" that -ENOMEM has the bits set. |
1398 | */ |
1399 | #ifndef HAVE_ARCH_UNMAPPED_AREA |
1400 | unsigned long |
1401 | arch_get_unmapped_area(struct file *filp, unsigned long addr, |
1402 | unsigned long len, unsigned long pgoff, unsigned long flags) |
1403 | { |
1404 | struct mm_struct *mm = current->mm; |
1405 | struct vm_area_struct *vma; |
1406 | unsigned long start_addr; |
1407 | |
1408 | if (len > TASK_SIZE) |
1409 | return -ENOMEM; |
1410 | |
1411 | if (flags & MAP_FIXED) |
1412 | return addr; |
1413 | |
1414 | if (addr) { |
1415 | addr = PAGE_ALIGN(addr); |
1416 | vma = find_vma(mm, addr); |
1417 | if (TASK_SIZE - len >= addr && |
1418 | (!vma || addr + len <= vma->vm_start)) |
1419 | return addr; |
1420 | } |
1421 | if (len > mm->cached_hole_size) { |
1422 | start_addr = addr = mm->free_area_cache; |
1423 | } else { |
1424 | start_addr = addr = TASK_UNMAPPED_BASE; |
1425 | mm->cached_hole_size = 0; |
1426 | } |
1427 | |
1428 | full_search: |
1429 | for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { |
1430 | /* At this point: (!vma || addr < vma->vm_end). */ |
1431 | if (TASK_SIZE - len < addr) { |
1432 | /* |
1433 | * Start a new search - just in case we missed |
1434 | * some holes. |
1435 | */ |
1436 | if (start_addr != TASK_UNMAPPED_BASE) { |
1437 | addr = TASK_UNMAPPED_BASE; |
1438 | start_addr = addr; |
1439 | mm->cached_hole_size = 0; |
1440 | goto full_search; |
1441 | } |
1442 | return -ENOMEM; |
1443 | } |
1444 | if (!vma || addr + len <= vma->vm_start) { |
1445 | /* |
1446 | * Remember the place where we stopped the search: |
1447 | */ |
1448 | mm->free_area_cache = addr + len; |
1449 | return addr; |
1450 | } |
1451 | if (addr + mm->cached_hole_size < vma->vm_start) |
1452 | mm->cached_hole_size = vma->vm_start - addr; |
1453 | addr = vma->vm_end; |
1454 | } |
1455 | } |
1456 | #endif |
1457 | |
1458 | void arch_unmap_area(struct mm_struct *mm, unsigned long addr) |
1459 | { |
1460 | /* |
1461 | * Is this a new hole at the lowest possible address? |
1462 | */ |
1463 | if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { |
1464 | mm->free_area_cache = addr; |
1465 | mm->cached_hole_size = ~0UL; |
1466 | } |
1467 | } |
1468 | |
1469 | /* |
1470 | * This mmap-allocator allocates new areas top-down from below the |
1471 | * stack's low limit (the base): |
1472 | */ |
1473 | #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN |
1474 | unsigned long |
1475 | arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, |
1476 | const unsigned long len, const unsigned long pgoff, |
1477 | const unsigned long flags) |
1478 | { |
1479 | struct vm_area_struct *vma; |
1480 | struct mm_struct *mm = current->mm; |
1481 | unsigned long addr = addr0; |
1482 | |
1483 | /* requested length too big for entire address space */ |
1484 | if (len > TASK_SIZE) |
1485 | return -ENOMEM; |
1486 | |
1487 | if (flags & MAP_FIXED) |
1488 | return addr; |
1489 | |
1490 | /* requesting a specific address */ |
1491 | if (addr) { |
1492 | addr = PAGE_ALIGN(addr); |
1493 | vma = find_vma(mm, addr); |
1494 | if (TASK_SIZE - len >= addr && |
1495 | (!vma || addr + len <= vma->vm_start)) |
1496 | return addr; |
1497 | } |
1498 | |
1499 | /* check if free_area_cache is useful for us */ |
1500 | if (len <= mm->cached_hole_size) { |
1501 | mm->cached_hole_size = 0; |
1502 | mm->free_area_cache = mm->mmap_base; |
1503 | } |
1504 | |
1505 | /* either no address requested or can't fit in requested address hole */ |
1506 | addr = mm->free_area_cache; |
1507 | |
1508 | /* make sure it can fit in the remaining address space */ |
1509 | if (addr > len) { |
1510 | vma = find_vma(mm, addr-len); |
1511 | if (!vma || addr <= vma->vm_start) |
1512 | /* remember the address as a hint for next time */ |
1513 | return (mm->free_area_cache = addr-len); |
1514 | } |
1515 | |
1516 | if (mm->mmap_base < len) |
1517 | goto bottomup; |
1518 | |
1519 | addr = mm->mmap_base-len; |
1520 | |
1521 | do { |
1522 | /* |
1523 | * Lookup failure means no vma is above this address, |
1524 | * else if new region fits below vma->vm_start, |
1525 | * return with success: |
1526 | */ |
1527 | vma = find_vma(mm, addr); |
1528 | if (!vma || addr+len <= vma->vm_start) |
1529 | /* remember the address as a hint for next time */ |
1530 | return (mm->free_area_cache = addr); |
1531 | |
1532 | /* remember the largest hole we saw so far */ |
1533 | if (addr + mm->cached_hole_size < vma->vm_start) |
1534 | mm->cached_hole_size = vma->vm_start - addr; |
1535 | |
1536 | /* try just below the current vma->vm_start */ |
1537 | addr = vma->vm_start-len; |
1538 | } while (len < vma->vm_start); |
1539 | |
1540 | bottomup: |
1541 | /* |
1542 | * A failed mmap() very likely causes application failure, |
1543 | * so fall back to the bottom-up function here. This scenario |
1544 | * can happen with large stack limits and large mmap() |
1545 | * allocations. |
1546 | */ |
1547 | mm->cached_hole_size = ~0UL; |
1548 | mm->free_area_cache = TASK_UNMAPPED_BASE; |
1549 | addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); |
1550 | /* |
1551 | * Restore the topdown base: |
1552 | */ |
1553 | mm->free_area_cache = mm->mmap_base; |
1554 | mm->cached_hole_size = ~0UL; |
1555 | |
1556 | return addr; |
1557 | } |
1558 | #endif |
1559 | |
1560 | void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) |
1561 | { |
1562 | /* |
1563 | * Is this a new hole at the highest possible address? |
1564 | */ |
1565 | if (addr > mm->free_area_cache) |
1566 | mm->free_area_cache = addr; |
1567 | |
1568 | /* dont allow allocations above current base */ |
1569 | if (mm->free_area_cache > mm->mmap_base) |
1570 | mm->free_area_cache = mm->mmap_base; |
1571 | } |
1572 | |
1573 | unsigned long |
1574 | get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, |
1575 | unsigned long pgoff, unsigned long flags) |
1576 | { |
1577 | unsigned long (*get_area)(struct file *, unsigned long, |
1578 | unsigned long, unsigned long, unsigned long); |
1579 | |
1580 | unsigned long error = arch_mmap_check(addr, len, flags); |
1581 | if (error) |
1582 | return error; |
1583 | |
1584 | /* Careful about overflows.. */ |
1585 | if (len > TASK_SIZE) |
1586 | return -ENOMEM; |
1587 | |
1588 | get_area = current->mm->get_unmapped_area; |
1589 | if (file && file->f_op && file->f_op->get_unmapped_area) |
1590 | get_area = file->f_op->get_unmapped_area; |
1591 | addr = get_area(file, addr, len, pgoff, flags); |
1592 | if (IS_ERR_VALUE(addr)) |
1593 | return addr; |
1594 | |
1595 | if (addr > TASK_SIZE - len) |
1596 | return -ENOMEM; |
1597 | if (addr & ~PAGE_MASK) |
1598 | return -EINVAL; |
1599 | |
1600 | return arch_rebalance_pgtables(addr, len); |
1601 | } |
1602 | |
1603 | EXPORT_SYMBOL(get_unmapped_area); |
1604 | |
1605 | /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ |
1606 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
1607 | { |
1608 | struct vm_area_struct *vma = NULL; |
1609 | |
1610 | if (mm) { |
1611 | /* Check the cache first. */ |
1612 | /* (Cache hit rate is typically around 35%.) */ |
1613 | vma = mm->mmap_cache; |
1614 | if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { |
1615 | struct rb_node * rb_node; |
1616 | |
1617 | rb_node = mm->mm_rb.rb_node; |
1618 | vma = NULL; |
1619 | |
1620 | while (rb_node) { |
1621 | struct vm_area_struct * vma_tmp; |
1622 | |
1623 | vma_tmp = rb_entry(rb_node, |
1624 | struct vm_area_struct, vm_rb); |
1625 | |
1626 | if (vma_tmp->vm_end > addr) { |
1627 | vma = vma_tmp; |
1628 | if (vma_tmp->vm_start <= addr) |
1629 | break; |
1630 | rb_node = rb_node->rb_left; |
1631 | } else |
1632 | rb_node = rb_node->rb_right; |
1633 | } |
1634 | if (vma) |
1635 | mm->mmap_cache = vma; |
1636 | } |
1637 | } |
1638 | return vma; |
1639 | } |
1640 | |
1641 | EXPORT_SYMBOL(find_vma); |
1642 | |
1643 | /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ |
1644 | struct vm_area_struct * |
1645 | find_vma_prev(struct mm_struct *mm, unsigned long addr, |
1646 | struct vm_area_struct **pprev) |
1647 | { |
1648 | struct vm_area_struct *vma = NULL, *prev = NULL; |
1649 | struct rb_node *rb_node; |
1650 | if (!mm) |
1651 | goto out; |
1652 | |
1653 | /* Guard against addr being lower than the first VMA */ |
1654 | vma = mm->mmap; |
1655 | |
1656 | /* Go through the RB tree quickly. */ |
1657 | rb_node = mm->mm_rb.rb_node; |
1658 | |
1659 | while (rb_node) { |
1660 | struct vm_area_struct *vma_tmp; |
1661 | vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); |
1662 | |
1663 | if (addr < vma_tmp->vm_end) { |
1664 | rb_node = rb_node->rb_left; |
1665 | } else { |
1666 | prev = vma_tmp; |
1667 | if (!prev->vm_next || (addr < prev->vm_next->vm_end)) |
1668 | break; |
1669 | rb_node = rb_node->rb_right; |
1670 | } |
1671 | } |
1672 | |
1673 | out: |
1674 | *pprev = prev; |
1675 | return prev ? prev->vm_next : vma; |
1676 | } |
1677 | |
1678 | /* |
1679 | * Verify that the stack growth is acceptable and |
1680 | * update accounting. This is shared with both the |
1681 | * grow-up and grow-down cases. |
1682 | */ |
1683 | static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) |
1684 | { |
1685 | struct mm_struct *mm = vma->vm_mm; |
1686 | struct rlimit *rlim = current->signal->rlim; |
1687 | unsigned long new_start; |
1688 | |
1689 | /* address space limit tests */ |
1690 | if (!may_expand_vm(mm, grow)) |
1691 | return -ENOMEM; |
1692 | |
1693 | /* Stack limit test */ |
1694 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur)) |
1695 | return -ENOMEM; |
1696 | |
1697 | /* mlock limit tests */ |
1698 | if (vma->vm_flags & VM_LOCKED) { |
1699 | unsigned long locked; |
1700 | unsigned long limit; |
1701 | locked = mm->locked_vm + grow; |
1702 | limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); |
1703 | limit >>= PAGE_SHIFT; |
1704 | if (locked > limit && !capable(CAP_IPC_LOCK)) |
1705 | return -ENOMEM; |
1706 | } |
1707 | |
1708 | /* Check to ensure the stack will not grow into a hugetlb-only region */ |
1709 | new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : |
1710 | vma->vm_end - size; |
1711 | if (is_hugepage_only_range(vma->vm_mm, new_start, size)) |
1712 | return -EFAULT; |
1713 | |
1714 | /* |
1715 | * Overcommit.. This must be the final test, as it will |
1716 | * update security statistics. |
1717 | */ |
1718 | if (security_vm_enough_memory_mm(mm, grow)) |
1719 | return -ENOMEM; |
1720 | |
1721 | /* Ok, everything looks good - let it rip */ |
1722 | mm->total_vm += grow; |
1723 | if (vma->vm_flags & VM_LOCKED) |
1724 | mm->locked_vm += grow; |
1725 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); |
1726 | return 0; |
1727 | } |
1728 | |
1729 | #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) |
1730 | /* |
1731 | * PA-RISC uses this for its stack; IA64 for its Register Backing Store. |
1732 | * vma is the last one with address > vma->vm_end. Have to extend vma. |
1733 | */ |
1734 | int expand_upwards(struct vm_area_struct *vma, unsigned long address) |
1735 | { |
1736 | int error; |
1737 | |
1738 | if (!(vma->vm_flags & VM_GROWSUP)) |
1739 | return -EFAULT; |
1740 | |
1741 | /* |
1742 | * We must make sure the anon_vma is allocated |
1743 | * so that the anon_vma locking is not a noop. |
1744 | */ |
1745 | if (unlikely(anon_vma_prepare(vma))) |
1746 | return -ENOMEM; |
1747 | vma_lock_anon_vma(vma); |
1748 | |
1749 | /* |
1750 | * vma->vm_start/vm_end cannot change under us because the caller |
1751 | * is required to hold the mmap_sem in read mode. We need the |
1752 | * anon_vma lock to serialize against concurrent expand_stacks. |
1753 | * Also guard against wrapping around to address 0. |
1754 | */ |
1755 | if (address < PAGE_ALIGN(address+4)) |
1756 | address = PAGE_ALIGN(address+4); |
1757 | else { |
1758 | vma_unlock_anon_vma(vma); |
1759 | return -ENOMEM; |
1760 | } |
1761 | error = 0; |
1762 | |
1763 | /* Somebody else might have raced and expanded it already */ |
1764 | if (address > vma->vm_end) { |
1765 | unsigned long size, grow; |
1766 | |
1767 | size = address - vma->vm_start; |
1768 | grow = (address - vma->vm_end) >> PAGE_SHIFT; |
1769 | |
1770 | error = acct_stack_growth(vma, size, grow); |
1771 | if (!error) { |
1772 | vma->vm_end = address; |
1773 | perf_event_mmap(vma); |
1774 | } |
1775 | } |
1776 | vma_unlock_anon_vma(vma); |
1777 | khugepaged_enter_vma_merge(vma); |
1778 | return error; |
1779 | } |
1780 | #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ |
1781 | |
1782 | /* |
1783 | * vma is the first one with address < vma->vm_start. Have to extend vma. |
1784 | */ |
1785 | static int expand_downwards(struct vm_area_struct *vma, |
1786 | unsigned long address) |
1787 | { |
1788 | int error; |
1789 | |
1790 | /* |
1791 | * We must make sure the anon_vma is allocated |
1792 | * so that the anon_vma locking is not a noop. |
1793 | */ |
1794 | if (unlikely(anon_vma_prepare(vma))) |
1795 | return -ENOMEM; |
1796 | |
1797 | address &= PAGE_MASK; |
1798 | error = security_file_mmap(NULL, 0, 0, 0, address, 1); |
1799 | if (error) |
1800 | return error; |
1801 | |
1802 | vma_lock_anon_vma(vma); |
1803 | |
1804 | /* |
1805 | * vma->vm_start/vm_end cannot change under us because the caller |
1806 | * is required to hold the mmap_sem in read mode. We need the |
1807 | * anon_vma lock to serialize against concurrent expand_stacks. |
1808 | */ |
1809 | |
1810 | /* Somebody else might have raced and expanded it already */ |
1811 | if (address < vma->vm_start) { |
1812 | unsigned long size, grow; |
1813 | |
1814 | size = vma->vm_end - address; |
1815 | grow = (vma->vm_start - address) >> PAGE_SHIFT; |
1816 | |
1817 | error = acct_stack_growth(vma, size, grow); |
1818 | if (!error) { |
1819 | vma->vm_start = address; |
1820 | vma->vm_pgoff -= grow; |
1821 | perf_event_mmap(vma); |
1822 | } |
1823 | } |
1824 | vma_unlock_anon_vma(vma); |
1825 | khugepaged_enter_vma_merge(vma); |
1826 | return error; |
1827 | } |
1828 | |
1829 | int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) |
1830 | { |
1831 | return expand_downwards(vma, address); |
1832 | } |
1833 | |
1834 | #ifdef CONFIG_STACK_GROWSUP |
1835 | int expand_stack(struct vm_area_struct *vma, unsigned long address) |
1836 | { |
1837 | return expand_upwards(vma, address); |
1838 | } |
1839 | |
1840 | struct vm_area_struct * |
1841 | find_extend_vma(struct mm_struct *mm, unsigned long addr) |
1842 | { |
1843 | struct vm_area_struct *vma, *prev; |
1844 | |
1845 | addr &= PAGE_MASK; |
1846 | vma = find_vma_prev(mm, addr, &prev); |
1847 | if (vma && (vma->vm_start <= addr)) |
1848 | return vma; |
1849 | if (!prev || expand_stack(prev, addr)) |
1850 | return NULL; |
1851 | if (prev->vm_flags & VM_LOCKED) { |
1852 | mlock_vma_pages_range(prev, addr, prev->vm_end); |
1853 | } |
1854 | return prev; |
1855 | } |
1856 | #else |
1857 | int expand_stack(struct vm_area_struct *vma, unsigned long address) |
1858 | { |
1859 | return expand_downwards(vma, address); |
1860 | } |
1861 | |
1862 | struct vm_area_struct * |
1863 | find_extend_vma(struct mm_struct * mm, unsigned long addr) |
1864 | { |
1865 | struct vm_area_struct * vma; |
1866 | unsigned long start; |
1867 | |
1868 | addr &= PAGE_MASK; |
1869 | vma = find_vma(mm,addr); |
1870 | if (!vma) |
1871 | return NULL; |
1872 | if (vma->vm_start <= addr) |
1873 | return vma; |
1874 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
1875 | return NULL; |
1876 | start = vma->vm_start; |
1877 | if (expand_stack(vma, addr)) |
1878 | return NULL; |
1879 | if (vma->vm_flags & VM_LOCKED) { |
1880 | mlock_vma_pages_range(vma, addr, start); |
1881 | } |
1882 | return vma; |
1883 | } |
1884 | #endif |
1885 | |
1886 | /* |
1887 | * Ok - we have the memory areas we should free on the vma list, |
1888 | * so release them, and do the vma updates. |
1889 | * |
1890 | * Called with the mm semaphore held. |
1891 | */ |
1892 | static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) |
1893 | { |
1894 | /* Update high watermark before we lower total_vm */ |
1895 | update_hiwater_vm(mm); |
1896 | do { |
1897 | long nrpages = vma_pages(vma); |
1898 | |
1899 | mm->total_vm -= nrpages; |
1900 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); |
1901 | vma = remove_vma(vma); |
1902 | } while (vma); |
1903 | validate_mm(mm); |
1904 | } |
1905 | |
1906 | /* |
1907 | * Get rid of page table information in the indicated region. |
1908 | * |
1909 | * Called with the mm semaphore held. |
1910 | */ |
1911 | static void unmap_region(struct mm_struct *mm, |
1912 | struct vm_area_struct *vma, struct vm_area_struct *prev, |
1913 | unsigned long start, unsigned long end) |
1914 | { |
1915 | struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; |
1916 | struct mmu_gather *tlb; |
1917 | unsigned long nr_accounted = 0; |
1918 | |
1919 | lru_add_drain(); |
1920 | tlb = tlb_gather_mmu(mm, 0); |
1921 | update_hiwater_rss(mm); |
1922 | unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); |
1923 | vm_unacct_memory(nr_accounted); |
1924 | free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, |
1925 | next? next->vm_start: 0); |
1926 | tlb_finish_mmu(tlb, start, end); |
1927 | } |
1928 | |
1929 | /* |
1930 | * Create a list of vma's touched by the unmap, removing them from the mm's |
1931 | * vma list as we go.. |
1932 | */ |
1933 | static void |
1934 | detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, |
1935 | struct vm_area_struct *prev, unsigned long end) |
1936 | { |
1937 | struct vm_area_struct **insertion_point; |
1938 | struct vm_area_struct *tail_vma = NULL; |
1939 | unsigned long addr; |
1940 | |
1941 | insertion_point = (prev ? &prev->vm_next : &mm->mmap); |
1942 | vma->vm_prev = NULL; |
1943 | do { |
1944 | rb_erase(&vma->vm_rb, &mm->mm_rb); |
1945 | mm->map_count--; |
1946 | tail_vma = vma; |
1947 | vma = vma->vm_next; |
1948 | } while (vma && vma->vm_start < end); |
1949 | *insertion_point = vma; |
1950 | if (vma) |
1951 | vma->vm_prev = prev; |
1952 | tail_vma->vm_next = NULL; |
1953 | if (mm->unmap_area == arch_unmap_area) |
1954 | addr = prev ? prev->vm_end : mm->mmap_base; |
1955 | else |
1956 | addr = vma ? vma->vm_start : mm->mmap_base; |
1957 | mm->unmap_area(mm, addr); |
1958 | mm->mmap_cache = NULL; /* Kill the cache. */ |
1959 | } |
1960 | |
1961 | /* |
1962 | * __split_vma() bypasses sysctl_max_map_count checking. We use this on the |
1963 | * munmap path where it doesn't make sense to fail. |
1964 | */ |
1965 | static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma, |
1966 | unsigned long addr, int new_below) |
1967 | { |
1968 | struct mempolicy *pol; |
1969 | struct vm_area_struct *new; |
1970 | int err = -ENOMEM; |
1971 | |
1972 | if (is_vm_hugetlb_page(vma) && (addr & |
1973 | ~(huge_page_mask(hstate_vma(vma))))) |
1974 | return -EINVAL; |
1975 | |
1976 | new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
1977 | if (!new) |
1978 | goto out_err; |
1979 | |
1980 | /* most fields are the same, copy all, and then fixup */ |
1981 | *new = *vma; |
1982 | |
1983 | INIT_LIST_HEAD(&new->anon_vma_chain); |
1984 | |
1985 | if (new_below) |
1986 | new->vm_end = addr; |
1987 | else { |
1988 | new->vm_start = addr; |
1989 | new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); |
1990 | } |
1991 | |
1992 | pol = mpol_dup(vma_policy(vma)); |
1993 | if (IS_ERR(pol)) { |
1994 | err = PTR_ERR(pol); |
1995 | goto out_free_vma; |
1996 | } |
1997 | vma_set_policy(new, pol); |
1998 | |
1999 | if (anon_vma_clone(new, vma)) |
2000 | goto out_free_mpol; |
2001 | |
2002 | if (new->vm_file) { |
2003 | get_file(new->vm_file); |
2004 | if (vma->vm_flags & VM_EXECUTABLE) |
2005 | added_exe_file_vma(mm); |
2006 | } |
2007 | |
2008 | if (new->vm_ops && new->vm_ops->open) |
2009 | new->vm_ops->open(new); |
2010 | |
2011 | if (new_below) |
2012 | err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + |
2013 | ((addr - new->vm_start) >> PAGE_SHIFT), new); |
2014 | else |
2015 | err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); |
2016 | |
2017 | /* Success. */ |
2018 | if (!err) |
2019 | return 0; |
2020 | |
2021 | /* Clean everything up if vma_adjust failed. */ |
2022 | if (new->vm_ops && new->vm_ops->close) |
2023 | new->vm_ops->close(new); |
2024 | if (new->vm_file) { |
2025 | if (vma->vm_flags & VM_EXECUTABLE) |
2026 | removed_exe_file_vma(mm); |
2027 | fput(new->vm_file); |
2028 | } |
2029 | unlink_anon_vmas(new); |
2030 | out_free_mpol: |
2031 | mpol_put(pol); |
2032 | out_free_vma: |
2033 | kmem_cache_free(vm_area_cachep, new); |
2034 | out_err: |
2035 | return err; |
2036 | } |
2037 | |
2038 | /* |
2039 | * Split a vma into two pieces at address 'addr', a new vma is allocated |
2040 | * either for the first part or the tail. |
2041 | */ |
2042 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, |
2043 | unsigned long addr, int new_below) |
2044 | { |
2045 | if (mm->map_count >= sysctl_max_map_count) |
2046 | return -ENOMEM; |
2047 | |
2048 | return __split_vma(mm, vma, addr, new_below); |
2049 | } |
2050 | |
2051 | /* Munmap is split into 2 main parts -- this part which finds |
2052 | * what needs doing, and the areas themselves, which do the |
2053 | * work. This now handles partial unmappings. |
2054 | * Jeremy Fitzhardinge <jeremy@goop.org> |
2055 | */ |
2056 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) |
2057 | { |
2058 | unsigned long end; |
2059 | struct vm_area_struct *vma, *prev, *last; |
2060 | |
2061 | if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) |
2062 | return -EINVAL; |
2063 | |
2064 | if ((len = PAGE_ALIGN(len)) == 0) |
2065 | return -EINVAL; |
2066 | |
2067 | /* Find the first overlapping VMA */ |
2068 | vma = find_vma_prev(mm, start, &prev); |
2069 | if (!vma) |
2070 | return 0; |
2071 | /* we have start < vma->vm_end */ |
2072 | |
2073 | /* if it doesn't overlap, we have nothing.. */ |
2074 | end = start + len; |
2075 | if (vma->vm_start >= end) |
2076 | return 0; |
2077 | |
2078 | /* |
2079 | * If we need to split any vma, do it now to save pain later. |
2080 | * |
2081 | * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially |
2082 | * unmapped vm_area_struct will remain in use: so lower split_vma |
2083 | * places tmp vma above, and higher split_vma places tmp vma below. |
2084 | */ |
2085 | if (start > vma->vm_start) { |
2086 | int error; |
2087 | |
2088 | /* |
2089 | * Make sure that map_count on return from munmap() will |
2090 | * not exceed its limit; but let map_count go just above |
2091 | * its limit temporarily, to help free resources as expected. |
2092 | */ |
2093 | if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) |
2094 | return -ENOMEM; |
2095 | |
2096 | error = __split_vma(mm, vma, start, 0); |
2097 | if (error) |
2098 | return error; |
2099 | prev = vma; |
2100 | } |
2101 | |
2102 | /* Does it split the last one? */ |
2103 | last = find_vma(mm, end); |
2104 | if (last && end > last->vm_start) { |
2105 | int error = __split_vma(mm, last, end, 1); |
2106 | if (error) |
2107 | return error; |
2108 | } |
2109 | vma = prev? prev->vm_next: mm->mmap; |
2110 | |
2111 | /* |
2112 | * unlock any mlock()ed ranges before detaching vmas |
2113 | */ |
2114 | if (mm->locked_vm) { |
2115 | struct vm_area_struct *tmp = vma; |
2116 | while (tmp && tmp->vm_start < end) { |
2117 | if (tmp->vm_flags & VM_LOCKED) { |
2118 | mm->locked_vm -= vma_pages(tmp); |
2119 | munlock_vma_pages_all(tmp); |
2120 | } |
2121 | tmp = tmp->vm_next; |
2122 | } |
2123 | } |
2124 | |
2125 | /* |
2126 | * Remove the vma's, and unmap the actual pages |
2127 | */ |
2128 | detach_vmas_to_be_unmapped(mm, vma, prev, end); |
2129 | unmap_region(mm, vma, prev, start, end); |
2130 | |
2131 | /* Fix up all other VM information */ |
2132 | remove_vma_list(mm, vma); |
2133 | |
2134 | return 0; |
2135 | } |
2136 | |
2137 | EXPORT_SYMBOL(do_munmap); |
2138 | |
2139 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
2140 | { |
2141 | int ret; |
2142 | struct mm_struct *mm = current->mm; |
2143 | |
2144 | profile_munmap(addr); |
2145 | |
2146 | down_write(&mm->mmap_sem); |
2147 | ret = do_munmap(mm, addr, len); |
2148 | up_write(&mm->mmap_sem); |
2149 | return ret; |
2150 | } |
2151 | |
2152 | static inline void verify_mm_writelocked(struct mm_struct *mm) |
2153 | { |
2154 | #ifdef CONFIG_DEBUG_VM |
2155 | if (unlikely(down_read_trylock(&mm->mmap_sem))) { |
2156 | WARN_ON(1); |
2157 | up_read(&mm->mmap_sem); |
2158 | } |
2159 | #endif |
2160 | } |
2161 | |
2162 | /* |
2163 | * this is really a simplified "do_mmap". it only handles |
2164 | * anonymous maps. eventually we may be able to do some |
2165 | * brk-specific accounting here. |
2166 | */ |
2167 | unsigned long do_brk(unsigned long addr, unsigned long len) |
2168 | { |
2169 | struct mm_struct * mm = current->mm; |
2170 | struct vm_area_struct * vma, * prev; |
2171 | unsigned long flags; |
2172 | struct rb_node ** rb_link, * rb_parent; |
2173 | pgoff_t pgoff = addr >> PAGE_SHIFT; |
2174 | int error; |
2175 | |
2176 | len = PAGE_ALIGN(len); |
2177 | if (!len) |
2178 | return addr; |
2179 | |
2180 | error = security_file_mmap(NULL, 0, 0, 0, addr, 1); |
2181 | if (error) |
2182 | return error; |
2183 | |
2184 | flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; |
2185 | |
2186 | error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); |
2187 | if (error & ~PAGE_MASK) |
2188 | return error; |
2189 | |
2190 | /* |
2191 | * mlock MCL_FUTURE? |
2192 | */ |
2193 | if (mm->def_flags & VM_LOCKED) { |
2194 | unsigned long locked, lock_limit; |
2195 | locked = len >> PAGE_SHIFT; |
2196 | locked += mm->locked_vm; |
2197 | lock_limit = rlimit(RLIMIT_MEMLOCK); |
2198 | lock_limit >>= PAGE_SHIFT; |
2199 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
2200 | return -EAGAIN; |
2201 | } |
2202 | |
2203 | /* |
2204 | * mm->mmap_sem is required to protect against another thread |
2205 | * changing the mappings in case we sleep. |
2206 | */ |
2207 | verify_mm_writelocked(mm); |
2208 | |
2209 | /* |
2210 | * Clear old maps. this also does some error checking for us |
2211 | */ |
2212 | munmap_back: |
2213 | vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); |
2214 | if (vma && vma->vm_start < addr + len) { |
2215 | if (do_munmap(mm, addr, len)) |
2216 | return -ENOMEM; |
2217 | goto munmap_back; |
2218 | } |
2219 | |
2220 | /* Check against address space limits *after* clearing old maps... */ |
2221 | if (!may_expand_vm(mm, len >> PAGE_SHIFT)) |
2222 | return -ENOMEM; |
2223 | |
2224 | if (mm->map_count > sysctl_max_map_count) |
2225 | return -ENOMEM; |
2226 | |
2227 | if (security_vm_enough_memory(len >> PAGE_SHIFT)) |
2228 | return -ENOMEM; |
2229 | |
2230 | /* Can we just expand an old private anonymous mapping? */ |
2231 | vma = vma_merge(mm, prev, addr, addr + len, flags, |
2232 | NULL, NULL, pgoff, NULL); |
2233 | if (vma) |
2234 | goto out; |
2235 | |
2236 | /* |
2237 | * create a vma struct for an anonymous mapping |
2238 | */ |
2239 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
2240 | if (!vma) { |
2241 | vm_unacct_memory(len >> PAGE_SHIFT); |
2242 | return -ENOMEM; |
2243 | } |
2244 | |
2245 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
2246 | vma->vm_mm = mm; |
2247 | vma->vm_start = addr; |
2248 | vma->vm_end = addr + len; |
2249 | vma->vm_pgoff = pgoff; |
2250 | vma->vm_flags = flags; |
2251 | vma->vm_page_prot = vm_get_page_prot(flags); |
2252 | vma_link(mm, vma, prev, rb_link, rb_parent); |
2253 | out: |
2254 | perf_event_mmap(vma); |
2255 | mm->total_vm += len >> PAGE_SHIFT; |
2256 | if (flags & VM_LOCKED) { |
2257 | if (!mlock_vma_pages_range(vma, addr, addr + len)) |
2258 | mm->locked_vm += (len >> PAGE_SHIFT); |
2259 | } |
2260 | return addr; |
2261 | } |
2262 | |
2263 | EXPORT_SYMBOL(do_brk); |
2264 | |
2265 | /* Release all mmaps. */ |
2266 | void exit_mmap(struct mm_struct *mm) |
2267 | { |
2268 | struct mmu_gather *tlb; |
2269 | struct vm_area_struct *vma; |
2270 | unsigned long nr_accounted = 0; |
2271 | unsigned long end; |
2272 | |
2273 | /* mm's last user has gone, and its about to be pulled down */ |
2274 | mmu_notifier_release(mm); |
2275 | |
2276 | if (mm->locked_vm) { |
2277 | vma = mm->mmap; |
2278 | while (vma) { |
2279 | if (vma->vm_flags & VM_LOCKED) |
2280 | munlock_vma_pages_all(vma); |
2281 | vma = vma->vm_next; |
2282 | } |
2283 | } |
2284 | |
2285 | arch_exit_mmap(mm); |
2286 | |
2287 | vma = mm->mmap; |
2288 | if (!vma) /* Can happen if dup_mmap() received an OOM */ |
2289 | return; |
2290 | |
2291 | lru_add_drain(); |
2292 | flush_cache_mm(mm); |
2293 | tlb = tlb_gather_mmu(mm, 1); |
2294 | /* update_hiwater_rss(mm) here? but nobody should be looking */ |
2295 | /* Use -1 here to ensure all VMAs in the mm are unmapped */ |
2296 | end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); |
2297 | vm_unacct_memory(nr_accounted); |
2298 | |
2299 | free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); |
2300 | tlb_finish_mmu(tlb, 0, end); |
2301 | |
2302 | /* |
2303 | * Walk the list again, actually closing and freeing it, |
2304 | * with preemption enabled, without holding any MM locks. |
2305 | */ |
2306 | while (vma) |
2307 | vma = remove_vma(vma); |
2308 | |
2309 | BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); |
2310 | } |
2311 | |
2312 | /* Insert vm structure into process list sorted by address |
2313 | * and into the inode's i_mmap tree. If vm_file is non-NULL |
2314 | * then i_mmap_lock is taken here. |
2315 | */ |
2316 | int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) |
2317 | { |
2318 | struct vm_area_struct * __vma, * prev; |
2319 | struct rb_node ** rb_link, * rb_parent; |
2320 | |
2321 | /* |
2322 | * The vm_pgoff of a purely anonymous vma should be irrelevant |
2323 | * until its first write fault, when page's anon_vma and index |
2324 | * are set. But now set the vm_pgoff it will almost certainly |
2325 | * end up with (unless mremap moves it elsewhere before that |
2326 | * first wfault), so /proc/pid/maps tells a consistent story. |
2327 | * |
2328 | * By setting it to reflect the virtual start address of the |
2329 | * vma, merges and splits can happen in a seamless way, just |
2330 | * using the existing file pgoff checks and manipulations. |
2331 | * Similarly in do_mmap_pgoff and in do_brk. |
2332 | */ |
2333 | if (!vma->vm_file) { |
2334 | BUG_ON(vma->anon_vma); |
2335 | vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; |
2336 | } |
2337 | __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); |
2338 | if (__vma && __vma->vm_start < vma->vm_end) |
2339 | return -ENOMEM; |
2340 | if ((vma->vm_flags & VM_ACCOUNT) && |
2341 | security_vm_enough_memory_mm(mm, vma_pages(vma))) |
2342 | return -ENOMEM; |
2343 | vma_link(mm, vma, prev, rb_link, rb_parent); |
2344 | return 0; |
2345 | } |
2346 | |
2347 | /* |
2348 | * Copy the vma structure to a new location in the same mm, |
2349 | * prior to moving page table entries, to effect an mremap move. |
2350 | */ |
2351 | struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, |
2352 | unsigned long addr, unsigned long len, pgoff_t pgoff) |
2353 | { |
2354 | struct vm_area_struct *vma = *vmap; |
2355 | unsigned long vma_start = vma->vm_start; |
2356 | struct mm_struct *mm = vma->vm_mm; |
2357 | struct vm_area_struct *new_vma, *prev; |
2358 | struct rb_node **rb_link, *rb_parent; |
2359 | struct mempolicy *pol; |
2360 | |
2361 | /* |
2362 | * If anonymous vma has not yet been faulted, update new pgoff |
2363 | * to match new location, to increase its chance of merging. |
2364 | */ |
2365 | if (!vma->vm_file && !vma->anon_vma) |
2366 | pgoff = addr >> PAGE_SHIFT; |
2367 | |
2368 | find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); |
2369 | new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, |
2370 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); |
2371 | if (new_vma) { |
2372 | /* |
2373 | * Source vma may have been merged into new_vma |
2374 | */ |
2375 | if (vma_start >= new_vma->vm_start && |
2376 | vma_start < new_vma->vm_end) |
2377 | *vmap = new_vma; |
2378 | } else { |
2379 | new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
2380 | if (new_vma) { |
2381 | *new_vma = *vma; |
2382 | pol = mpol_dup(vma_policy(vma)); |
2383 | if (IS_ERR(pol)) |
2384 | goto out_free_vma; |
2385 | INIT_LIST_HEAD(&new_vma->anon_vma_chain); |
2386 | if (anon_vma_clone(new_vma, vma)) |
2387 | goto out_free_mempol; |
2388 | vma_set_policy(new_vma, pol); |
2389 | new_vma->vm_start = addr; |
2390 | new_vma->vm_end = addr + len; |
2391 | new_vma->vm_pgoff = pgoff; |
2392 | if (new_vma->vm_file) { |
2393 | get_file(new_vma->vm_file); |
2394 | if (vma->vm_flags & VM_EXECUTABLE) |
2395 | added_exe_file_vma(mm); |
2396 | } |
2397 | if (new_vma->vm_ops && new_vma->vm_ops->open) |
2398 | new_vma->vm_ops->open(new_vma); |
2399 | vma_link(mm, new_vma, prev, rb_link, rb_parent); |
2400 | } |
2401 | } |
2402 | return new_vma; |
2403 | |
2404 | out_free_mempol: |
2405 | mpol_put(pol); |
2406 | out_free_vma: |
2407 | kmem_cache_free(vm_area_cachep, new_vma); |
2408 | return NULL; |
2409 | } |
2410 | |
2411 | /* |
2412 | * Return true if the calling process may expand its vm space by the passed |
2413 | * number of pages |
2414 | */ |
2415 | int may_expand_vm(struct mm_struct *mm, unsigned long npages) |
2416 | { |
2417 | unsigned long cur = mm->total_vm; /* pages */ |
2418 | unsigned long lim; |
2419 | |
2420 | lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT; |
2421 | |
2422 | if (cur + npages > lim) |
2423 | return 0; |
2424 | return 1; |
2425 | } |
2426 | |
2427 | |
2428 | static int special_mapping_fault(struct vm_area_struct *vma, |
2429 | struct vm_fault *vmf) |
2430 | { |
2431 | pgoff_t pgoff; |
2432 | struct page **pages; |
2433 | |
2434 | /* |
2435 | * special mappings have no vm_file, and in that case, the mm |
2436 | * uses vm_pgoff internally. So we have to subtract it from here. |
2437 | * We are allowed to do this because we are the mm; do not copy |
2438 | * this code into drivers! |
2439 | */ |
2440 | pgoff = vmf->pgoff - vma->vm_pgoff; |
2441 | |
2442 | for (pages = vma->vm_private_data; pgoff && *pages; ++pages) |
2443 | pgoff--; |
2444 | |
2445 | if (*pages) { |
2446 | struct page *page = *pages; |
2447 | get_page(page); |
2448 | vmf->page = page; |
2449 | return 0; |
2450 | } |
2451 | |
2452 | return VM_FAULT_SIGBUS; |
2453 | } |
2454 | |
2455 | /* |
2456 | * Having a close hook prevents vma merging regardless of flags. |
2457 | */ |
2458 | static void special_mapping_close(struct vm_area_struct *vma) |
2459 | { |
2460 | } |
2461 | |
2462 | static const struct vm_operations_struct special_mapping_vmops = { |
2463 | .close = special_mapping_close, |
2464 | .fault = special_mapping_fault, |
2465 | }; |
2466 | |
2467 | /* |
2468 | * Called with mm->mmap_sem held for writing. |
2469 | * Insert a new vma covering the given region, with the given flags. |
2470 | * Its pages are supplied by the given array of struct page *. |
2471 | * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. |
2472 | * The region past the last page supplied will always produce SIGBUS. |
2473 | * The array pointer and the pages it points to are assumed to stay alive |
2474 | * for as long as this mapping might exist. |
2475 | */ |
2476 | int install_special_mapping(struct mm_struct *mm, |
2477 | unsigned long addr, unsigned long len, |
2478 | unsigned long vm_flags, struct page **pages) |
2479 | { |
2480 | int ret; |
2481 | struct vm_area_struct *vma; |
2482 | |
2483 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
2484 | if (unlikely(vma == NULL)) |
2485 | return -ENOMEM; |
2486 | |
2487 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
2488 | vma->vm_mm = mm; |
2489 | vma->vm_start = addr; |
2490 | vma->vm_end = addr + len; |
2491 | |
2492 | vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; |
2493 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
2494 | |
2495 | vma->vm_ops = &special_mapping_vmops; |
2496 | vma->vm_private_data = pages; |
2497 | |
2498 | ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); |
2499 | if (ret) |
2500 | goto out; |
2501 | |
2502 | ret = insert_vm_struct(mm, vma); |
2503 | if (ret) |
2504 | goto out; |
2505 | |
2506 | mm->total_vm += len >> PAGE_SHIFT; |
2507 | |
2508 | perf_event_mmap(vma); |
2509 | |
2510 | return 0; |
2511 | |
2512 | out: |
2513 | kmem_cache_free(vm_area_cachep, vma); |
2514 | return ret; |
2515 | } |
2516 | |
2517 | static DEFINE_MUTEX(mm_all_locks_mutex); |
2518 | |
2519 | static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) |
2520 | { |
2521 | if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) { |
2522 | /* |
2523 | * The LSB of head.next can't change from under us |
2524 | * because we hold the mm_all_locks_mutex. |
2525 | */ |
2526 | spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem); |
2527 | /* |
2528 | * We can safely modify head.next after taking the |
2529 | * anon_vma->root->lock. If some other vma in this mm shares |
2530 | * the same anon_vma we won't take it again. |
2531 | * |
2532 | * No need of atomic instructions here, head.next |
2533 | * can't change from under us thanks to the |
2534 | * anon_vma->root->lock. |
2535 | */ |
2536 | if (__test_and_set_bit(0, (unsigned long *) |
2537 | &anon_vma->root->head.next)) |
2538 | BUG(); |
2539 | } |
2540 | } |
2541 | |
2542 | static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) |
2543 | { |
2544 | if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
2545 | /* |
2546 | * AS_MM_ALL_LOCKS can't change from under us because |
2547 | * we hold the mm_all_locks_mutex. |
2548 | * |
2549 | * Operations on ->flags have to be atomic because |
2550 | * even if AS_MM_ALL_LOCKS is stable thanks to the |
2551 | * mm_all_locks_mutex, there may be other cpus |
2552 | * changing other bitflags in parallel to us. |
2553 | */ |
2554 | if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) |
2555 | BUG(); |
2556 | spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem); |
2557 | } |
2558 | } |
2559 | |
2560 | /* |
2561 | * This operation locks against the VM for all pte/vma/mm related |
2562 | * operations that could ever happen on a certain mm. This includes |
2563 | * vmtruncate, try_to_unmap, and all page faults. |
2564 | * |
2565 | * The caller must take the mmap_sem in write mode before calling |
2566 | * mm_take_all_locks(). The caller isn't allowed to release the |
2567 | * mmap_sem until mm_drop_all_locks() returns. |
2568 | * |
2569 | * mmap_sem in write mode is required in order to block all operations |
2570 | * that could modify pagetables and free pages without need of |
2571 | * altering the vma layout (for example populate_range() with |
2572 | * nonlinear vmas). It's also needed in write mode to avoid new |
2573 | * anon_vmas to be associated with existing vmas. |
2574 | * |
2575 | * A single task can't take more than one mm_take_all_locks() in a row |
2576 | * or it would deadlock. |
2577 | * |
2578 | * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in |
2579 | * mapping->flags avoid to take the same lock twice, if more than one |
2580 | * vma in this mm is backed by the same anon_vma or address_space. |
2581 | * |
2582 | * We can take all the locks in random order because the VM code |
2583 | * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never |
2584 | * takes more than one of them in a row. Secondly we're protected |
2585 | * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. |
2586 | * |
2587 | * mm_take_all_locks() and mm_drop_all_locks are expensive operations |
2588 | * that may have to take thousand of locks. |
2589 | * |
2590 | * mm_take_all_locks() can fail if it's interrupted by signals. |
2591 | */ |
2592 | int mm_take_all_locks(struct mm_struct *mm) |
2593 | { |
2594 | struct vm_area_struct *vma; |
2595 | struct anon_vma_chain *avc; |
2596 | int ret = -EINTR; |
2597 | |
2598 | BUG_ON(down_read_trylock(&mm->mmap_sem)); |
2599 | |
2600 | mutex_lock(&mm_all_locks_mutex); |
2601 | |
2602 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
2603 | if (signal_pending(current)) |
2604 | goto out_unlock; |
2605 | if (vma->vm_file && vma->vm_file->f_mapping) |
2606 | vm_lock_mapping(mm, vma->vm_file->f_mapping); |
2607 | } |
2608 | |
2609 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
2610 | if (signal_pending(current)) |
2611 | goto out_unlock; |
2612 | if (vma->anon_vma) |
2613 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
2614 | vm_lock_anon_vma(mm, avc->anon_vma); |
2615 | } |
2616 | |
2617 | ret = 0; |
2618 | |
2619 | out_unlock: |
2620 | if (ret) |
2621 | mm_drop_all_locks(mm); |
2622 | |
2623 | return ret; |
2624 | } |
2625 | |
2626 | static void vm_unlock_anon_vma(struct anon_vma *anon_vma) |
2627 | { |
2628 | if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) { |
2629 | /* |
2630 | * The LSB of head.next can't change to 0 from under |
2631 | * us because we hold the mm_all_locks_mutex. |
2632 | * |
2633 | * We must however clear the bitflag before unlocking |
2634 | * the vma so the users using the anon_vma->head will |
2635 | * never see our bitflag. |
2636 | * |
2637 | * No need of atomic instructions here, head.next |
2638 | * can't change from under us until we release the |
2639 | * anon_vma->root->lock. |
2640 | */ |
2641 | if (!__test_and_clear_bit(0, (unsigned long *) |
2642 | &anon_vma->root->head.next)) |
2643 | BUG(); |
2644 | anon_vma_unlock(anon_vma); |
2645 | } |
2646 | } |
2647 | |
2648 | static void vm_unlock_mapping(struct address_space *mapping) |
2649 | { |
2650 | if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { |
2651 | /* |
2652 | * AS_MM_ALL_LOCKS can't change to 0 from under us |
2653 | * because we hold the mm_all_locks_mutex. |
2654 | */ |
2655 | spin_unlock(&mapping->i_mmap_lock); |
2656 | if (!test_and_clear_bit(AS_MM_ALL_LOCKS, |
2657 | &mapping->flags)) |
2658 | BUG(); |
2659 | } |
2660 | } |
2661 | |
2662 | /* |
2663 | * The mmap_sem cannot be released by the caller until |
2664 | * mm_drop_all_locks() returns. |
2665 | */ |
2666 | void mm_drop_all_locks(struct mm_struct *mm) |
2667 | { |
2668 | struct vm_area_struct *vma; |
2669 | struct anon_vma_chain *avc; |
2670 | |
2671 | BUG_ON(down_read_trylock(&mm->mmap_sem)); |
2672 | BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); |
2673 | |
2674 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
2675 | if (vma->anon_vma) |
2676 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) |
2677 | vm_unlock_anon_vma(avc->anon_vma); |
2678 | if (vma->vm_file && vma->vm_file->f_mapping) |
2679 | vm_unlock_mapping(vma->vm_file->f_mapping); |
2680 | } |
2681 | |
2682 | mutex_unlock(&mm_all_locks_mutex); |
2683 | } |
2684 | |
2685 | /* |
2686 | * initialise the VMA slab |
2687 | */ |
2688 | void __init mmap_init(void) |
2689 | { |
2690 | int ret; |
2691 | |
2692 | ret = percpu_counter_init(&vm_committed_as, 0); |
2693 | VM_BUG_ON(ret); |
2694 | } |
2695 |
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