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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/kernel.h> | |
10 | #include <linux/slab.h> | |
11 | #include <linux/backing-dev.h> | |
12 | #include <linux/mm.h> | |
13 | #include <linux/shm.h> | |
14 | #include <linux/mman.h> | |
15 | #include <linux/pagemap.h> | |
16 | #include <linux/swap.h> | |
17 | #include <linux/syscalls.h> | |
18 | #include <linux/capability.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/personality.h> | |
23 | #include <linux/security.h> | |
24 | #include <linux/hugetlb.h> | |
25 | #include <linux/profile.h> | |
26 | #include <linux/export.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/mempolicy.h> | |
29 | #include <linux/rmap.h> | |
30 | #include <linux/mmu_notifier.h> | |
31 | #include <linux/perf_event.h> | |
32 | #include <linux/audit.h> | |
33 | #include <linux/khugepaged.h> | |
34 | #include <linux/uprobes.h> | |
35 | #include <linux/rbtree_augmented.h> | |
36 | #include <linux/sched/sysctl.h> | |
37 | #include <linux/notifier.h> | |
38 | #include <linux/memory.h> | |
39 | ||
40 | #include <asm/uaccess.h> | |
41 | #include <asm/cacheflush.h> | |
42 | #include <asm/tlb.h> | |
43 | #include <asm/mmu_context.h> | |
44 | ||
45 | #include "internal.h" | |
46 | ||
47 | #ifndef arch_mmap_check | |
48 | #define arch_mmap_check(addr, len, flags) (0) | |
49 | #endif | |
50 | ||
51 | #ifndef arch_rebalance_pgtables | |
52 | #define arch_rebalance_pgtables(addr, len) (addr) | |
53 | #endif | |
54 | ||
55 | static void unmap_region(struct mm_struct *mm, | |
56 | struct vm_area_struct *vma, struct vm_area_struct *prev, | |
57 | unsigned long start, unsigned long end); | |
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 __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ | |
88 | int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ | |
89 | int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; | |
90 | unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ | |
91 | unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ | |
92 | /* | |
93 | * Make sure vm_committed_as in one cacheline and not cacheline shared with | |
94 | * other variables. It can be updated by several CPUs frequently. | |
95 | */ | |
96 | struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; | |
97 | ||
98 | /* | |
99 | * The global memory commitment made in the system can be a metric | |
100 | * that can be used to drive ballooning decisions when Linux is hosted | |
101 | * as a guest. On Hyper-V, the host implements a policy engine for dynamically | |
102 | * balancing memory across competing virtual machines that are hosted. | |
103 | * Several metrics drive this policy engine including the guest reported | |
104 | * memory commitment. | |
105 | */ | |
106 | unsigned long vm_memory_committed(void) | |
107 | { | |
108 | return percpu_counter_read_positive(&vm_committed_as); | |
109 | } | |
110 | EXPORT_SYMBOL_GPL(vm_memory_committed); | |
111 | ||
112 | /* | |
113 | * Check that a process has enough memory to allocate a new virtual | |
114 | * mapping. 0 means there is enough memory for the allocation to | |
115 | * succeed and -ENOMEM implies there is not. | |
116 | * | |
117 | * We currently support three overcommit policies, which are set via the | |
118 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting | |
119 | * | |
120 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. | |
121 | * Additional code 2002 Jul 20 by Robert Love. | |
122 | * | |
123 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. | |
124 | * | |
125 | * Note this is a helper function intended to be used by LSMs which | |
126 | * wish to use this logic. | |
127 | */ | |
128 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) | |
129 | { | |
130 | unsigned long free, allowed, reserve; | |
131 | ||
132 | vm_acct_memory(pages); | |
133 | ||
134 | /* | |
135 | * Sometimes we want to use more memory than we have | |
136 | */ | |
137 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) | |
138 | return 0; | |
139 | ||
140 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { | |
141 | free = global_page_state(NR_FREE_PAGES); | |
142 | free += global_page_state(NR_FILE_PAGES); | |
143 | ||
144 | /* | |
145 | * shmem pages shouldn't be counted as free in this | |
146 | * case, they can't be purged, only swapped out, and | |
147 | * that won't affect the overall amount of available | |
148 | * memory in the system. | |
149 | */ | |
150 | free -= global_page_state(NR_SHMEM); | |
151 | ||
152 | free += get_nr_swap_pages(); | |
153 | ||
154 | /* | |
155 | * Any slabs which are created with the | |
156 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents | |
157 | * which are reclaimable, under pressure. The dentry | |
158 | * cache and most inode caches should fall into this | |
159 | */ | |
160 | free += global_page_state(NR_SLAB_RECLAIMABLE); | |
161 | ||
162 | /* | |
163 | * Leave reserved pages. The pages are not for anonymous pages. | |
164 | */ | |
165 | if (free <= totalreserve_pages) | |
166 | goto error; | |
167 | else | |
168 | free -= totalreserve_pages; | |
169 | ||
170 | /* | |
171 | * Reserve some for root | |
172 | */ | |
173 | if (!cap_sys_admin) | |
174 | free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
175 | ||
176 | if (free > pages) | |
177 | return 0; | |
178 | ||
179 | goto error; | |
180 | } | |
181 | ||
182 | allowed = (totalram_pages - hugetlb_total_pages()) | |
183 | * sysctl_overcommit_ratio / 100; | |
184 | /* | |
185 | * Reserve some for root | |
186 | */ | |
187 | if (!cap_sys_admin) | |
188 | allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); | |
189 | allowed += total_swap_pages; | |
190 | ||
191 | /* | |
192 | * Don't let a single process grow so big a user can't recover | |
193 | */ | |
194 | if (mm) { | |
195 | reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); | |
196 | allowed -= min(mm->total_vm / 32, reserve); | |
197 | } | |
198 | ||
199 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) | |
200 | return 0; | |
201 | error: | |
202 | vm_unacct_memory(pages); | |
203 | ||
204 | return -ENOMEM; | |
205 | } | |
206 | ||
207 | /* | |
208 | * Requires inode->i_mapping->i_mmap_mutex | |
209 | */ | |
210 | static void __remove_shared_vm_struct(struct vm_area_struct *vma, | |
211 | struct file *file, struct address_space *mapping) | |
212 | { | |
213 | if (vma->vm_flags & VM_DENYWRITE) | |
214 | atomic_inc(&file_inode(file)->i_writecount); | |
215 | if (vma->vm_flags & VM_SHARED) | |
216 | mapping->i_mmap_writable--; | |
217 | ||
218 | flush_dcache_mmap_lock(mapping); | |
219 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) | |
220 | list_del_init(&vma->shared.nonlinear); | |
221 | else | |
222 | vma_interval_tree_remove(vma, &mapping->i_mmap); | |
223 | flush_dcache_mmap_unlock(mapping); | |
224 | } | |
225 | ||
226 | /* | |
227 | * Unlink a file-based vm structure from its interval tree, to hide | |
228 | * vma from rmap and vmtruncate before freeing its page tables. | |
229 | */ | |
230 | void unlink_file_vma(struct vm_area_struct *vma) | |
231 | { | |
232 | struct file *file = vma->vm_file; | |
233 | ||
234 | if (file) { | |
235 | struct address_space *mapping = file->f_mapping; | |
236 | mutex_lock(&mapping->i_mmap_mutex); | |
237 | __remove_shared_vm_struct(vma, file, mapping); | |
238 | mutex_unlock(&mapping->i_mmap_mutex); | |
239 | } | |
240 | } | |
241 | ||
242 | /* | |
243 | * Close a vm structure and free it, returning the next. | |
244 | */ | |
245 | static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) | |
246 | { | |
247 | struct vm_area_struct *next = vma->vm_next; | |
248 | ||
249 | might_sleep(); | |
250 | if (vma->vm_ops && vma->vm_ops->close) | |
251 | vma->vm_ops->close(vma); | |
252 | if (vma->vm_file) | |
253 | fput(vma->vm_file); | |
254 | mpol_put(vma_policy(vma)); | |
255 | kmem_cache_free(vm_area_cachep, vma); | |
256 | return next; | |
257 | } | |
258 | ||
259 | static unsigned long do_brk(unsigned long addr, unsigned long len); | |
260 | ||
261 | SYSCALL_DEFINE1(brk, unsigned long, brk) | |
262 | { | |
263 | unsigned long rlim, retval; | |
264 | unsigned long newbrk, oldbrk; | |
265 | struct mm_struct *mm = current->mm; | |
266 | unsigned long min_brk; | |
267 | bool populate; | |
268 | ||
269 | down_write(&mm->mmap_sem); | |
270 | ||
271 | #ifdef CONFIG_COMPAT_BRK | |
272 | /* | |
273 | * CONFIG_COMPAT_BRK can still be overridden by setting | |
274 | * randomize_va_space to 2, which will still cause mm->start_brk | |
275 | * to be arbitrarily shifted | |
276 | */ | |
277 | if (current->brk_randomized) | |
278 | min_brk = mm->start_brk; | |
279 | else | |
280 | min_brk = mm->end_data; | |
281 | #else | |
282 | min_brk = mm->start_brk; | |
283 | #endif | |
284 | if (brk < min_brk) | |
285 | goto out; | |
286 | ||
287 | /* | |
288 | * Check against rlimit here. If this check is done later after the test | |
289 | * of oldbrk with newbrk then it can escape the test and let the data | |
290 | * segment grow beyond its set limit the in case where the limit is | |
291 | * not page aligned -Ram Gupta | |
292 | */ | |
293 | rlim = rlimit(RLIMIT_DATA); | |
294 | if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + | |
295 | (mm->end_data - mm->start_data) > rlim) | |
296 | goto out; | |
297 | ||
298 | newbrk = PAGE_ALIGN(brk); | |
299 | oldbrk = PAGE_ALIGN(mm->brk); | |
300 | if (oldbrk == newbrk) | |
301 | goto set_brk; | |
302 | ||
303 | /* Always allow shrinking brk. */ | |
304 | if (brk <= mm->brk) { | |
305 | if (!do_munmap(mm, newbrk, oldbrk-newbrk)) | |
306 | goto set_brk; | |
307 | goto out; | |
308 | } | |
309 | ||
310 | /* Check against existing mmap mappings. */ | |
311 | if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) | |
312 | goto out; | |
313 | ||
314 | /* Ok, looks good - let it rip. */ | |
315 | if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) | |
316 | goto out; | |
317 | ||
318 | set_brk: | |
319 | mm->brk = brk; | |
320 | populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; | |
321 | up_write(&mm->mmap_sem); | |
322 | if (populate) | |
323 | mm_populate(oldbrk, newbrk - oldbrk); | |
324 | return brk; | |
325 | ||
326 | out: | |
327 | retval = mm->brk; | |
328 | up_write(&mm->mmap_sem); | |
329 | return retval; | |
330 | } | |
331 | ||
332 | static long vma_compute_subtree_gap(struct vm_area_struct *vma) | |
333 | { | |
334 | unsigned long max, subtree_gap; | |
335 | max = vma->vm_start; | |
336 | if (vma->vm_prev) | |
337 | max -= vma->vm_prev->vm_end; | |
338 | if (vma->vm_rb.rb_left) { | |
339 | subtree_gap = rb_entry(vma->vm_rb.rb_left, | |
340 | struct vm_area_struct, vm_rb)->rb_subtree_gap; | |
341 | if (subtree_gap > max) | |
342 | max = subtree_gap; | |
343 | } | |
344 | if (vma->vm_rb.rb_right) { | |
345 | subtree_gap = rb_entry(vma->vm_rb.rb_right, | |
346 | struct vm_area_struct, vm_rb)->rb_subtree_gap; | |
347 | if (subtree_gap > max) | |
348 | max = subtree_gap; | |
349 | } | |
350 | return max; | |
351 | } | |
352 | ||
353 | #ifdef CONFIG_DEBUG_VM_RB | |
354 | static int browse_rb(struct rb_root *root) | |
355 | { | |
356 | int i = 0, j, bug = 0; | |
357 | struct rb_node *nd, *pn = NULL; | |
358 | unsigned long prev = 0, pend = 0; | |
359 | ||
360 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { | |
361 | struct vm_area_struct *vma; | |
362 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); | |
363 | if (vma->vm_start < prev) { | |
364 | printk("vm_start %lx prev %lx\n", vma->vm_start, prev); | |
365 | bug = 1; | |
366 | } | |
367 | if (vma->vm_start < pend) { | |
368 | printk("vm_start %lx pend %lx\n", vma->vm_start, pend); | |
369 | bug = 1; | |
370 | } | |
371 | if (vma->vm_start > vma->vm_end) { | |
372 | printk("vm_end %lx < vm_start %lx\n", | |
373 | vma->vm_end, vma->vm_start); | |
374 | bug = 1; | |
375 | } | |
376 | if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { | |
377 | printk("free gap %lx, correct %lx\n", | |
378 | vma->rb_subtree_gap, | |
379 | vma_compute_subtree_gap(vma)); | |
380 | bug = 1; | |
381 | } | |
382 | i++; | |
383 | pn = nd; | |
384 | prev = vma->vm_start; | |
385 | pend = vma->vm_end; | |
386 | } | |
387 | j = 0; | |
388 | for (nd = pn; nd; nd = rb_prev(nd)) | |
389 | j++; | |
390 | if (i != j) { | |
391 | printk("backwards %d, forwards %d\n", j, i); | |
392 | bug = 1; | |
393 | } | |
394 | return bug ? -1 : i; | |
395 | } | |
396 | ||
397 | static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) | |
398 | { | |
399 | struct rb_node *nd; | |
400 | ||
401 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { | |
402 | struct vm_area_struct *vma; | |
403 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); | |
404 | BUG_ON(vma != ignore && | |
405 | vma->rb_subtree_gap != vma_compute_subtree_gap(vma)); | |
406 | } | |
407 | } | |
408 | ||
409 | void validate_mm(struct mm_struct *mm) | |
410 | { | |
411 | int bug = 0; | |
412 | int i = 0; | |
413 | unsigned long highest_address = 0; | |
414 | struct vm_area_struct *vma = mm->mmap; | |
415 | while (vma) { | |
416 | struct anon_vma_chain *avc; | |
417 | vma_lock_anon_vma(vma); | |
418 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
419 | anon_vma_interval_tree_verify(avc); | |
420 | vma_unlock_anon_vma(vma); | |
421 | highest_address = vma->vm_end; | |
422 | vma = vma->vm_next; | |
423 | i++; | |
424 | } | |
425 | if (i != mm->map_count) { | |
426 | printk("map_count %d vm_next %d\n", mm->map_count, i); | |
427 | bug = 1; | |
428 | } | |
429 | if (highest_address != mm->highest_vm_end) { | |
430 | printk("mm->highest_vm_end %lx, found %lx\n", | |
431 | mm->highest_vm_end, highest_address); | |
432 | bug = 1; | |
433 | } | |
434 | i = browse_rb(&mm->mm_rb); | |
435 | if (i != mm->map_count) { | |
436 | printk("map_count %d rb %d\n", mm->map_count, i); | |
437 | bug = 1; | |
438 | } | |
439 | BUG_ON(bug); | |
440 | } | |
441 | #else | |
442 | #define validate_mm_rb(root, ignore) do { } while (0) | |
443 | #define validate_mm(mm) do { } while (0) | |
444 | #endif | |
445 | ||
446 | RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, | |
447 | unsigned long, rb_subtree_gap, vma_compute_subtree_gap) | |
448 | ||
449 | /* | |
450 | * Update augmented rbtree rb_subtree_gap values after vma->vm_start or | |
451 | * vma->vm_prev->vm_end values changed, without modifying the vma's position | |
452 | * in the rbtree. | |
453 | */ | |
454 | static void vma_gap_update(struct vm_area_struct *vma) | |
455 | { | |
456 | /* | |
457 | * As it turns out, RB_DECLARE_CALLBACKS() already created a callback | |
458 | * function that does exacltly what we want. | |
459 | */ | |
460 | vma_gap_callbacks_propagate(&vma->vm_rb, NULL); | |
461 | } | |
462 | ||
463 | static inline void vma_rb_insert(struct vm_area_struct *vma, | |
464 | struct rb_root *root) | |
465 | { | |
466 | /* All rb_subtree_gap values must be consistent prior to insertion */ | |
467 | validate_mm_rb(root, NULL); | |
468 | ||
469 | rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); | |
470 | } | |
471 | ||
472 | static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) | |
473 | { | |
474 | /* | |
475 | * All rb_subtree_gap values must be consistent prior to erase, | |
476 | * with the possible exception of the vma being erased. | |
477 | */ | |
478 | validate_mm_rb(root, vma); | |
479 | ||
480 | /* | |
481 | * Note rb_erase_augmented is a fairly large inline function, | |
482 | * so make sure we instantiate it only once with our desired | |
483 | * augmented rbtree callbacks. | |
484 | */ | |
485 | rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); | |
486 | } | |
487 | ||
488 | /* | |
489 | * vma has some anon_vma assigned, and is already inserted on that | |
490 | * anon_vma's interval trees. | |
491 | * | |
492 | * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the | |
493 | * vma must be removed from the anon_vma's interval trees using | |
494 | * anon_vma_interval_tree_pre_update_vma(). | |
495 | * | |
496 | * After the update, the vma will be reinserted using | |
497 | * anon_vma_interval_tree_post_update_vma(). | |
498 | * | |
499 | * The entire update must be protected by exclusive mmap_sem and by | |
500 | * the root anon_vma's mutex. | |
501 | */ | |
502 | static inline void | |
503 | anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) | |
504 | { | |
505 | struct anon_vma_chain *avc; | |
506 | ||
507 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
508 | anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); | |
509 | } | |
510 | ||
511 | static inline void | |
512 | anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) | |
513 | { | |
514 | struct anon_vma_chain *avc; | |
515 | ||
516 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
517 | anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); | |
518 | } | |
519 | ||
520 | static int find_vma_links(struct mm_struct *mm, unsigned long addr, | |
521 | unsigned long end, struct vm_area_struct **pprev, | |
522 | struct rb_node ***rb_link, struct rb_node **rb_parent) | |
523 | { | |
524 | struct rb_node **__rb_link, *__rb_parent, *rb_prev; | |
525 | ||
526 | __rb_link = &mm->mm_rb.rb_node; | |
527 | rb_prev = __rb_parent = NULL; | |
528 | ||
529 | while (*__rb_link) { | |
530 | struct vm_area_struct *vma_tmp; | |
531 | ||
532 | __rb_parent = *__rb_link; | |
533 | vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); | |
534 | ||
535 | if (vma_tmp->vm_end > addr) { | |
536 | /* Fail if an existing vma overlaps the area */ | |
537 | if (vma_tmp->vm_start < end) | |
538 | return -ENOMEM; | |
539 | __rb_link = &__rb_parent->rb_left; | |
540 | } else { | |
541 | rb_prev = __rb_parent; | |
542 | __rb_link = &__rb_parent->rb_right; | |
543 | } | |
544 | } | |
545 | ||
546 | *pprev = NULL; | |
547 | if (rb_prev) | |
548 | *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); | |
549 | *rb_link = __rb_link; | |
550 | *rb_parent = __rb_parent; | |
551 | return 0; | |
552 | } | |
553 | ||
554 | static unsigned long count_vma_pages_range(struct mm_struct *mm, | |
555 | unsigned long addr, unsigned long end) | |
556 | { | |
557 | unsigned long nr_pages = 0; | |
558 | struct vm_area_struct *vma; | |
559 | ||
560 | /* Find first overlaping mapping */ | |
561 | vma = find_vma_intersection(mm, addr, end); | |
562 | if (!vma) | |
563 | return 0; | |
564 | ||
565 | nr_pages = (min(end, vma->vm_end) - | |
566 | max(addr, vma->vm_start)) >> PAGE_SHIFT; | |
567 | ||
568 | /* Iterate over the rest of the overlaps */ | |
569 | for (vma = vma->vm_next; vma; vma = vma->vm_next) { | |
570 | unsigned long overlap_len; | |
571 | ||
572 | if (vma->vm_start > end) | |
573 | break; | |
574 | ||
575 | overlap_len = min(end, vma->vm_end) - vma->vm_start; | |
576 | nr_pages += overlap_len >> PAGE_SHIFT; | |
577 | } | |
578 | ||
579 | return nr_pages; | |
580 | } | |
581 | ||
582 | void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, | |
583 | struct rb_node **rb_link, struct rb_node *rb_parent) | |
584 | { | |
585 | /* Update tracking information for the gap following the new vma. */ | |
586 | if (vma->vm_next) | |
587 | vma_gap_update(vma->vm_next); | |
588 | else | |
589 | mm->highest_vm_end = vma->vm_end; | |
590 | ||
591 | /* | |
592 | * vma->vm_prev wasn't known when we followed the rbtree to find the | |
593 | * correct insertion point for that vma. As a result, we could not | |
594 | * update the vma vm_rb parents rb_subtree_gap values on the way down. | |
595 | * So, we first insert the vma with a zero rb_subtree_gap value | |
596 | * (to be consistent with what we did on the way down), and then | |
597 | * immediately update the gap to the correct value. Finally we | |
598 | * rebalance the rbtree after all augmented values have been set. | |
599 | */ | |
600 | rb_link_node(&vma->vm_rb, rb_parent, rb_link); | |
601 | vma->rb_subtree_gap = 0; | |
602 | vma_gap_update(vma); | |
603 | vma_rb_insert(vma, &mm->mm_rb); | |
604 | } | |
605 | ||
606 | static void __vma_link_file(struct vm_area_struct *vma) | |
607 | { | |
608 | struct file *file; | |
609 | ||
610 | file = vma->vm_file; | |
611 | if (file) { | |
612 | struct address_space *mapping = file->f_mapping; | |
613 | ||
614 | if (vma->vm_flags & VM_DENYWRITE) | |
615 | atomic_dec(&file_inode(file)->i_writecount); | |
616 | if (vma->vm_flags & VM_SHARED) | |
617 | mapping->i_mmap_writable++; | |
618 | ||
619 | flush_dcache_mmap_lock(mapping); | |
620 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) | |
621 | vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); | |
622 | else | |
623 | vma_interval_tree_insert(vma, &mapping->i_mmap); | |
624 | flush_dcache_mmap_unlock(mapping); | |
625 | } | |
626 | } | |
627 | ||
628 | static void | |
629 | __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, | |
630 | struct vm_area_struct *prev, struct rb_node **rb_link, | |
631 | struct rb_node *rb_parent) | |
632 | { | |
633 | __vma_link_list(mm, vma, prev, rb_parent); | |
634 | __vma_link_rb(mm, vma, rb_link, rb_parent); | |
635 | } | |
636 | ||
637 | static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, | |
638 | struct vm_area_struct *prev, struct rb_node **rb_link, | |
639 | struct rb_node *rb_parent) | |
640 | { | |
641 | struct address_space *mapping = NULL; | |
642 | ||
643 | if (vma->vm_file) | |
644 | mapping = vma->vm_file->f_mapping; | |
645 | ||
646 | if (mapping) | |
647 | mutex_lock(&mapping->i_mmap_mutex); | |
648 | ||
649 | __vma_link(mm, vma, prev, rb_link, rb_parent); | |
650 | __vma_link_file(vma); | |
651 | ||
652 | if (mapping) | |
653 | mutex_unlock(&mapping->i_mmap_mutex); | |
654 | ||
655 | mm->map_count++; | |
656 | validate_mm(mm); | |
657 | } | |
658 | ||
659 | /* | |
660 | * Helper for vma_adjust() in the split_vma insert case: insert a vma into the | |
661 | * mm's list and rbtree. It has already been inserted into the interval tree. | |
662 | */ | |
663 | static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) | |
664 | { | |
665 | struct vm_area_struct *prev; | |
666 | struct rb_node **rb_link, *rb_parent; | |
667 | ||
668 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, | |
669 | &prev, &rb_link, &rb_parent)) | |
670 | BUG(); | |
671 | __vma_link(mm, vma, prev, rb_link, rb_parent); | |
672 | mm->map_count++; | |
673 | } | |
674 | ||
675 | static inline void | |
676 | __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, | |
677 | struct vm_area_struct *prev) | |
678 | { | |
679 | struct vm_area_struct *next; | |
680 | ||
681 | vma_rb_erase(vma, &mm->mm_rb); | |
682 | prev->vm_next = next = vma->vm_next; | |
683 | if (next) | |
684 | next->vm_prev = prev; | |
685 | if (mm->mmap_cache == vma) | |
686 | mm->mmap_cache = prev; | |
687 | } | |
688 | ||
689 | /* | |
690 | * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that | |
691 | * is already present in an i_mmap tree without adjusting the tree. | |
692 | * The following helper function should be used when such adjustments | |
693 | * are necessary. The "insert" vma (if any) is to be inserted | |
694 | * before we drop the necessary locks. | |
695 | */ | |
696 | int vma_adjust(struct vm_area_struct *vma, unsigned long start, | |
697 | unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) | |
698 | { | |
699 | struct mm_struct *mm = vma->vm_mm; | |
700 | struct vm_area_struct *next = vma->vm_next; | |
701 | struct vm_area_struct *importer = NULL; | |
702 | struct address_space *mapping = NULL; | |
703 | struct rb_root *root = NULL; | |
704 | struct anon_vma *anon_vma = NULL; | |
705 | struct file *file = vma->vm_file; | |
706 | bool start_changed = false, end_changed = false; | |
707 | long adjust_next = 0; | |
708 | int remove_next = 0; | |
709 | ||
710 | if (next && !insert) { | |
711 | struct vm_area_struct *exporter = NULL; | |
712 | ||
713 | if (end >= next->vm_end) { | |
714 | /* | |
715 | * vma expands, overlapping all the next, and | |
716 | * perhaps the one after too (mprotect case 6). | |
717 | */ | |
718 | again: remove_next = 1 + (end > next->vm_end); | |
719 | end = next->vm_end; | |
720 | exporter = next; | |
721 | importer = vma; | |
722 | } else if (end > next->vm_start) { | |
723 | /* | |
724 | * vma expands, overlapping part of the next: | |
725 | * mprotect case 5 shifting the boundary up. | |
726 | */ | |
727 | adjust_next = (end - next->vm_start) >> PAGE_SHIFT; | |
728 | exporter = next; | |
729 | importer = vma; | |
730 | } else if (end < vma->vm_end) { | |
731 | /* | |
732 | * vma shrinks, and !insert tells it's not | |
733 | * split_vma inserting another: so it must be | |
734 | * mprotect case 4 shifting the boundary down. | |
735 | */ | |
736 | adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); | |
737 | exporter = vma; | |
738 | importer = next; | |
739 | } | |
740 | ||
741 | /* | |
742 | * Easily overlooked: when mprotect shifts the boundary, | |
743 | * make sure the expanding vma has anon_vma set if the | |
744 | * shrinking vma had, to cover any anon pages imported. | |
745 | */ | |
746 | if (exporter && exporter->anon_vma && !importer->anon_vma) { | |
747 | if (anon_vma_clone(importer, exporter)) | |
748 | return -ENOMEM; | |
749 | importer->anon_vma = exporter->anon_vma; | |
750 | } | |
751 | } | |
752 | ||
753 | if (file) { | |
754 | mapping = file->f_mapping; | |
755 | if (!(vma->vm_flags & VM_NONLINEAR)) { | |
756 | root = &mapping->i_mmap; | |
757 | uprobe_munmap(vma, vma->vm_start, vma->vm_end); | |
758 | ||
759 | if (adjust_next) | |
760 | uprobe_munmap(next, next->vm_start, | |
761 | next->vm_end); | |
762 | } | |
763 | ||
764 | mutex_lock(&mapping->i_mmap_mutex); | |
765 | if (insert) { | |
766 | /* | |
767 | * Put into interval tree now, so instantiated pages | |
768 | * are visible to arm/parisc __flush_dcache_page | |
769 | * throughout; but we cannot insert into address | |
770 | * space until vma start or end is updated. | |
771 | */ | |
772 | __vma_link_file(insert); | |
773 | } | |
774 | } | |
775 | ||
776 | vma_adjust_trans_huge(vma, start, end, adjust_next); | |
777 | ||
778 | anon_vma = vma->anon_vma; | |
779 | if (!anon_vma && adjust_next) | |
780 | anon_vma = next->anon_vma; | |
781 | if (anon_vma) { | |
782 | VM_BUG_ON(adjust_next && next->anon_vma && | |
783 | anon_vma != next->anon_vma); | |
784 | anon_vma_lock_write(anon_vma); | |
785 | anon_vma_interval_tree_pre_update_vma(vma); | |
786 | if (adjust_next) | |
787 | anon_vma_interval_tree_pre_update_vma(next); | |
788 | } | |
789 | ||
790 | if (root) { | |
791 | flush_dcache_mmap_lock(mapping); | |
792 | vma_interval_tree_remove(vma, root); | |
793 | if (adjust_next) | |
794 | vma_interval_tree_remove(next, root); | |
795 | } | |
796 | ||
797 | if (start != vma->vm_start) { | |
798 | vma->vm_start = start; | |
799 | start_changed = true; | |
800 | } | |
801 | if (end != vma->vm_end) { | |
802 | vma->vm_end = end; | |
803 | end_changed = true; | |
804 | } | |
805 | vma->vm_pgoff = pgoff; | |
806 | if (adjust_next) { | |
807 | next->vm_start += adjust_next << PAGE_SHIFT; | |
808 | next->vm_pgoff += adjust_next; | |
809 | } | |
810 | ||
811 | if (root) { | |
812 | if (adjust_next) | |
813 | vma_interval_tree_insert(next, root); | |
814 | vma_interval_tree_insert(vma, root); | |
815 | flush_dcache_mmap_unlock(mapping); | |
816 | } | |
817 | ||
818 | if (remove_next) { | |
819 | /* | |
820 | * vma_merge has merged next into vma, and needs | |
821 | * us to remove next before dropping the locks. | |
822 | */ | |
823 | __vma_unlink(mm, next, vma); | |
824 | if (file) | |
825 | __remove_shared_vm_struct(next, file, mapping); | |
826 | } else if (insert) { | |
827 | /* | |
828 | * split_vma has split insert from vma, and needs | |
829 | * us to insert it before dropping the locks | |
830 | * (it may either follow vma or precede it). | |
831 | */ | |
832 | __insert_vm_struct(mm, insert); | |
833 | } else { | |
834 | if (start_changed) | |
835 | vma_gap_update(vma); | |
836 | if (end_changed) { | |
837 | if (!next) | |
838 | mm->highest_vm_end = end; | |
839 | else if (!adjust_next) | |
840 | vma_gap_update(next); | |
841 | } | |
842 | } | |
843 | ||
844 | if (anon_vma) { | |
845 | anon_vma_interval_tree_post_update_vma(vma); | |
846 | if (adjust_next) | |
847 | anon_vma_interval_tree_post_update_vma(next); | |
848 | anon_vma_unlock_write(anon_vma); | |
849 | } | |
850 | if (mapping) | |
851 | mutex_unlock(&mapping->i_mmap_mutex); | |
852 | ||
853 | if (root) { | |
854 | uprobe_mmap(vma); | |
855 | ||
856 | if (adjust_next) | |
857 | uprobe_mmap(next); | |
858 | } | |
859 | ||
860 | if (remove_next) { | |
861 | if (file) { | |
862 | uprobe_munmap(next, next->vm_start, next->vm_end); | |
863 | fput(file); | |
864 | } | |
865 | if (next->anon_vma) | |
866 | anon_vma_merge(vma, next); | |
867 | mm->map_count--; | |
868 | mpol_put(vma_policy(next)); | |
869 | kmem_cache_free(vm_area_cachep, next); | |
870 | /* | |
871 | * In mprotect's case 6 (see comments on vma_merge), | |
872 | * we must remove another next too. It would clutter | |
873 | * up the code too much to do both in one go. | |
874 | */ | |
875 | next = vma->vm_next; | |
876 | if (remove_next == 2) | |
877 | goto again; | |
878 | else if (next) | |
879 | vma_gap_update(next); | |
880 | else | |
881 | mm->highest_vm_end = end; | |
882 | } | |
883 | if (insert && file) | |
884 | uprobe_mmap(insert); | |
885 | ||
886 | validate_mm(mm); | |
887 | ||
888 | return 0; | |
889 | } | |
890 | ||
891 | /* | |
892 | * If the vma has a ->close operation then the driver probably needs to release | |
893 | * per-vma resources, so we don't attempt to merge those. | |
894 | */ | |
895 | static inline int is_mergeable_vma(struct vm_area_struct *vma, | |
896 | struct file *file, unsigned long vm_flags) | |
897 | { | |
898 | if (vma->vm_flags ^ vm_flags) | |
899 | return 0; | |
900 | if (vma->vm_file != file) | |
901 | return 0; | |
902 | if (vma->vm_ops && vma->vm_ops->close) | |
903 | return 0; | |
904 | return 1; | |
905 | } | |
906 | ||
907 | static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, | |
908 | struct anon_vma *anon_vma2, | |
909 | struct vm_area_struct *vma) | |
910 | { | |
911 | /* | |
912 | * The list_is_singular() test is to avoid merging VMA cloned from | |
913 | * parents. This can improve scalability caused by anon_vma lock. | |
914 | */ | |
915 | if ((!anon_vma1 || !anon_vma2) && (!vma || | |
916 | list_is_singular(&vma->anon_vma_chain))) | |
917 | return 1; | |
918 | return anon_vma1 == anon_vma2; | |
919 | } | |
920 | ||
921 | /* | |
922 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) | |
923 | * in front of (at a lower virtual address and file offset than) the vma. | |
924 | * | |
925 | * We cannot merge two vmas if they have differently assigned (non-NULL) | |
926 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. | |
927 | * | |
928 | * We don't check here for the merged mmap wrapping around the end of pagecache | |
929 | * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which | |
930 | * wrap, nor mmaps which cover the final page at index -1UL. | |
931 | */ | |
932 | static int | |
933 | can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, | |
934 | struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) | |
935 | { | |
936 | if (is_mergeable_vma(vma, file, vm_flags) && | |
937 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { | |
938 | if (vma->vm_pgoff == vm_pgoff) | |
939 | return 1; | |
940 | } | |
941 | return 0; | |
942 | } | |
943 | ||
944 | /* | |
945 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) | |
946 | * beyond (at a higher virtual address and file offset than) the vma. | |
947 | * | |
948 | * We cannot merge two vmas if they have differently assigned (non-NULL) | |
949 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. | |
950 | */ | |
951 | static int | |
952 | can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, | |
953 | struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) | |
954 | { | |
955 | if (is_mergeable_vma(vma, file, vm_flags) && | |
956 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { | |
957 | pgoff_t vm_pglen; | |
958 | vm_pglen = vma_pages(vma); | |
959 | if (vma->vm_pgoff + vm_pglen == vm_pgoff) | |
960 | return 1; | |
961 | } | |
962 | return 0; | |
963 | } | |
964 | ||
965 | /* | |
966 | * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out | |
967 | * whether that can be merged with its predecessor or its successor. | |
968 | * Or both (it neatly fills a hole). | |
969 | * | |
970 | * In most cases - when called for mmap, brk or mremap - [addr,end) is | |
971 | * certain not to be mapped by the time vma_merge is called; but when | |
972 | * called for mprotect, it is certain to be already mapped (either at | |
973 | * an offset within prev, or at the start of next), and the flags of | |
974 | * this area are about to be changed to vm_flags - and the no-change | |
975 | * case has already been eliminated. | |
976 | * | |
977 | * The following mprotect cases have to be considered, where AAAA is | |
978 | * the area passed down from mprotect_fixup, never extending beyond one | |
979 | * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: | |
980 | * | |
981 | * AAAA AAAA AAAA AAAA | |
982 | * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX | |
983 | * cannot merge might become might become might become | |
984 | * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or | |
985 | * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or | |
986 | * mremap move: PPPPNNNNNNNN 8 | |
987 | * AAAA | |
988 | * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN | |
989 | * might become case 1 below case 2 below case 3 below | |
990 | * | |
991 | * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: | |
992 | * mprotect_fixup updates vm_flags & vm_page_prot on successful return. | |
993 | */ | |
994 | struct vm_area_struct *vma_merge(struct mm_struct *mm, | |
995 | struct vm_area_struct *prev, unsigned long addr, | |
996 | unsigned long end, unsigned long vm_flags, | |
997 | struct anon_vma *anon_vma, struct file *file, | |
998 | pgoff_t pgoff, struct mempolicy *policy) | |
999 | { | |
1000 | pgoff_t pglen = (end - addr) >> PAGE_SHIFT; | |
1001 | struct vm_area_struct *area, *next; | |
1002 | int err; | |
1003 | ||
1004 | /* | |
1005 | * We later require that vma->vm_flags == vm_flags, | |
1006 | * so this tests vma->vm_flags & VM_SPECIAL, too. | |
1007 | */ | |
1008 | if (vm_flags & VM_SPECIAL) | |
1009 | return NULL; | |
1010 | ||
1011 | if (prev) | |
1012 | next = prev->vm_next; | |
1013 | else | |
1014 | next = mm->mmap; | |
1015 | area = next; | |
1016 | if (next && next->vm_end == end) /* cases 6, 7, 8 */ | |
1017 | next = next->vm_next; | |
1018 | ||
1019 | /* | |
1020 | * Can it merge with the predecessor? | |
1021 | */ | |
1022 | if (prev && prev->vm_end == addr && | |
1023 | mpol_equal(vma_policy(prev), policy) && | |
1024 | can_vma_merge_after(prev, vm_flags, | |
1025 | anon_vma, file, pgoff)) { | |
1026 | /* | |
1027 | * OK, it can. Can we now merge in the successor as well? | |
1028 | */ | |
1029 | if (next && end == next->vm_start && | |
1030 | mpol_equal(policy, vma_policy(next)) && | |
1031 | can_vma_merge_before(next, vm_flags, | |
1032 | anon_vma, file, pgoff+pglen) && | |
1033 | is_mergeable_anon_vma(prev->anon_vma, | |
1034 | next->anon_vma, NULL)) { | |
1035 | /* cases 1, 6 */ | |
1036 | err = vma_adjust(prev, prev->vm_start, | |
1037 | next->vm_end, prev->vm_pgoff, NULL); | |
1038 | } else /* cases 2, 5, 7 */ | |
1039 | err = vma_adjust(prev, prev->vm_start, | |
1040 | end, prev->vm_pgoff, NULL); | |
1041 | if (err) | |
1042 | return NULL; | |
1043 | khugepaged_enter_vma_merge(prev); | |
1044 | return prev; | |
1045 | } | |
1046 | ||
1047 | /* | |
1048 | * Can this new request be merged in front of next? | |
1049 | */ | |
1050 | if (next && end == next->vm_start && | |
1051 | mpol_equal(policy, vma_policy(next)) && | |
1052 | can_vma_merge_before(next, vm_flags, | |
1053 | anon_vma, file, pgoff+pglen)) { | |
1054 | if (prev && addr < prev->vm_end) /* case 4 */ | |
1055 | err = vma_adjust(prev, prev->vm_start, | |
1056 | addr, prev->vm_pgoff, NULL); | |
1057 | else /* cases 3, 8 */ | |
1058 | err = vma_adjust(area, addr, next->vm_end, | |
1059 | next->vm_pgoff - pglen, NULL); | |
1060 | if (err) | |
1061 | return NULL; | |
1062 | khugepaged_enter_vma_merge(area); | |
1063 | return area; | |
1064 | } | |
1065 | ||
1066 | return NULL; | |
1067 | } | |
1068 | ||
1069 | /* | |
1070 | * Rough compatbility check to quickly see if it's even worth looking | |
1071 | * at sharing an anon_vma. | |
1072 | * | |
1073 | * They need to have the same vm_file, and the flags can only differ | |
1074 | * in things that mprotect may change. | |
1075 | * | |
1076 | * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that | |
1077 | * we can merge the two vma's. For example, we refuse to merge a vma if | |
1078 | * there is a vm_ops->close() function, because that indicates that the | |
1079 | * driver is doing some kind of reference counting. But that doesn't | |
1080 | * really matter for the anon_vma sharing case. | |
1081 | */ | |
1082 | static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) | |
1083 | { | |
1084 | return a->vm_end == b->vm_start && | |
1085 | mpol_equal(vma_policy(a), vma_policy(b)) && | |
1086 | a->vm_file == b->vm_file && | |
1087 | !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) && | |
1088 | b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); | |
1089 | } | |
1090 | ||
1091 | /* | |
1092 | * Do some basic sanity checking to see if we can re-use the anon_vma | |
1093 | * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be | |
1094 | * the same as 'old', the other will be the new one that is trying | |
1095 | * to share the anon_vma. | |
1096 | * | |
1097 | * NOTE! This runs with mm_sem held for reading, so it is possible that | |
1098 | * the anon_vma of 'old' is concurrently in the process of being set up | |
1099 | * by another page fault trying to merge _that_. But that's ok: if it | |
1100 | * is being set up, that automatically means that it will be a singleton | |
1101 | * acceptable for merging, so we can do all of this optimistically. But | |
1102 | * we do that ACCESS_ONCE() to make sure that we never re-load the pointer. | |
1103 | * | |
1104 | * IOW: that the "list_is_singular()" test on the anon_vma_chain only | |
1105 | * matters for the 'stable anon_vma' case (ie the thing we want to avoid | |
1106 | * is to return an anon_vma that is "complex" due to having gone through | |
1107 | * a fork). | |
1108 | * | |
1109 | * We also make sure that the two vma's are compatible (adjacent, | |
1110 | * and with the same memory policies). That's all stable, even with just | |
1111 | * a read lock on the mm_sem. | |
1112 | */ | |
1113 | static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) | |
1114 | { | |
1115 | if (anon_vma_compatible(a, b)) { | |
1116 | struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma); | |
1117 | ||
1118 | if (anon_vma && list_is_singular(&old->anon_vma_chain)) | |
1119 | return anon_vma; | |
1120 | } | |
1121 | return NULL; | |
1122 | } | |
1123 | ||
1124 | /* | |
1125 | * find_mergeable_anon_vma is used by anon_vma_prepare, to check | |
1126 | * neighbouring vmas for a suitable anon_vma, before it goes off | |
1127 | * to allocate a new anon_vma. It checks because a repetitive | |
1128 | * sequence of mprotects and faults may otherwise lead to distinct | |
1129 | * anon_vmas being allocated, preventing vma merge in subsequent | |
1130 | * mprotect. | |
1131 | */ | |
1132 | struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) | |
1133 | { | |
1134 | struct anon_vma *anon_vma; | |
1135 | struct vm_area_struct *near; | |
1136 | ||
1137 | near = vma->vm_next; | |
1138 | if (!near) | |
1139 | goto try_prev; | |
1140 | ||
1141 | anon_vma = reusable_anon_vma(near, vma, near); | |
1142 | if (anon_vma) | |
1143 | return anon_vma; | |
1144 | try_prev: | |
1145 | near = vma->vm_prev; | |
1146 | if (!near) | |
1147 | goto none; | |
1148 | ||
1149 | anon_vma = reusable_anon_vma(near, near, vma); | |
1150 | if (anon_vma) | |
1151 | return anon_vma; | |
1152 | none: | |
1153 | /* | |
1154 | * There's no absolute need to look only at touching neighbours: | |
1155 | * we could search further afield for "compatible" anon_vmas. | |
1156 | * But it would probably just be a waste of time searching, | |
1157 | * or lead to too many vmas hanging off the same anon_vma. | |
1158 | * We're trying to allow mprotect remerging later on, | |
1159 | * not trying to minimize memory used for anon_vmas. | |
1160 | */ | |
1161 | return NULL; | |
1162 | } | |
1163 | ||
1164 | #ifdef CONFIG_PROC_FS | |
1165 | void vm_stat_account(struct mm_struct *mm, unsigned long flags, | |
1166 | struct file *file, long pages) | |
1167 | { | |
1168 | const unsigned long stack_flags | |
1169 | = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); | |
1170 | ||
1171 | mm->total_vm += pages; | |
1172 | ||
1173 | if (file) { | |
1174 | mm->shared_vm += pages; | |
1175 | if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) | |
1176 | mm->exec_vm += pages; | |
1177 | } else if (flags & stack_flags) | |
1178 | mm->stack_vm += pages; | |
1179 | } | |
1180 | #endif /* CONFIG_PROC_FS */ | |
1181 | ||
1182 | /* | |
1183 | * If a hint addr is less than mmap_min_addr change hint to be as | |
1184 | * low as possible but still greater than mmap_min_addr | |
1185 | */ | |
1186 | static inline unsigned long round_hint_to_min(unsigned long hint) | |
1187 | { | |
1188 | hint &= PAGE_MASK; | |
1189 | if (((void *)hint != NULL) && | |
1190 | (hint < mmap_min_addr)) | |
1191 | return PAGE_ALIGN(mmap_min_addr); | |
1192 | return hint; | |
1193 | } | |
1194 | ||
1195 | /* | |
1196 | * The caller must hold down_write(¤t->mm->mmap_sem). | |
1197 | */ | |
1198 | ||
1199 | unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, | |
1200 | unsigned long len, unsigned long prot, | |
1201 | unsigned long flags, unsigned long pgoff, | |
1202 | unsigned long *populate) | |
1203 | { | |
1204 | struct mm_struct * mm = current->mm; | |
1205 | vm_flags_t vm_flags; | |
1206 | ||
1207 | *populate = 0; | |
1208 | ||
1209 | /* | |
1210 | * Does the application expect PROT_READ to imply PROT_EXEC? | |
1211 | * | |
1212 | * (the exception is when the underlying filesystem is noexec | |
1213 | * mounted, in which case we dont add PROT_EXEC.) | |
1214 | */ | |
1215 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) | |
1216 | if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) | |
1217 | prot |= PROT_EXEC; | |
1218 | ||
1219 | if (!len) | |
1220 | return -EINVAL; | |
1221 | ||
1222 | if (!(flags & MAP_FIXED)) | |
1223 | addr = round_hint_to_min(addr); | |
1224 | ||
1225 | /* Careful about overflows.. */ | |
1226 | len = PAGE_ALIGN(len); | |
1227 | if (!len) | |
1228 | return -ENOMEM; | |
1229 | ||
1230 | /* offset overflow? */ | |
1231 | if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) | |
1232 | return -EOVERFLOW; | |
1233 | ||
1234 | /* Too many mappings? */ | |
1235 | if (mm->map_count > sysctl_max_map_count) | |
1236 | return -ENOMEM; | |
1237 | ||
1238 | /* Obtain the address to map to. we verify (or select) it and ensure | |
1239 | * that it represents a valid section of the address space. | |
1240 | */ | |
1241 | addr = get_unmapped_area(file, addr, len, pgoff, flags); | |
1242 | if (addr & ~PAGE_MASK) | |
1243 | return addr; | |
1244 | ||
1245 | /* Do simple checking here so the lower-level routines won't have | |
1246 | * to. we assume access permissions have been handled by the open | |
1247 | * of the memory object, so we don't do any here. | |
1248 | */ | |
1249 | vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | | |
1250 | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; | |
1251 | ||
1252 | if (flags & MAP_LOCKED) | |
1253 | if (!can_do_mlock()) | |
1254 | return -EPERM; | |
1255 | ||
1256 | /* mlock MCL_FUTURE? */ | |
1257 | if (vm_flags & VM_LOCKED) { | |
1258 | unsigned long locked, lock_limit; | |
1259 | locked = len >> PAGE_SHIFT; | |
1260 | locked += mm->locked_vm; | |
1261 | lock_limit = rlimit(RLIMIT_MEMLOCK); | |
1262 | lock_limit >>= PAGE_SHIFT; | |
1263 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
1264 | return -EAGAIN; | |
1265 | } | |
1266 | ||
1267 | if (file) { | |
1268 | struct inode *inode = file_inode(file); | |
1269 | ||
1270 | switch (flags & MAP_TYPE) { | |
1271 | case MAP_SHARED: | |
1272 | if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) | |
1273 | return -EACCES; | |
1274 | ||
1275 | /* | |
1276 | * Make sure we don't allow writing to an append-only | |
1277 | * file.. | |
1278 | */ | |
1279 | if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) | |
1280 | return -EACCES; | |
1281 | ||
1282 | /* | |
1283 | * Make sure there are no mandatory locks on the file. | |
1284 | */ | |
1285 | if (locks_verify_locked(inode)) | |
1286 | return -EAGAIN; | |
1287 | ||
1288 | vm_flags |= VM_SHARED | VM_MAYSHARE; | |
1289 | if (!(file->f_mode & FMODE_WRITE)) | |
1290 | vm_flags &= ~(VM_MAYWRITE | VM_SHARED); | |
1291 | ||
1292 | /* fall through */ | |
1293 | case MAP_PRIVATE: | |
1294 | if (!(file->f_mode & FMODE_READ)) | |
1295 | return -EACCES; | |
1296 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { | |
1297 | if (vm_flags & VM_EXEC) | |
1298 | return -EPERM; | |
1299 | vm_flags &= ~VM_MAYEXEC; | |
1300 | } | |
1301 | ||
1302 | if (!file->f_op || !file->f_op->mmap) | |
1303 | return -ENODEV; | |
1304 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) | |
1305 | return -EINVAL; | |
1306 | break; | |
1307 | ||
1308 | default: | |
1309 | return -EINVAL; | |
1310 | } | |
1311 | } else { | |
1312 | switch (flags & MAP_TYPE) { | |
1313 | case MAP_SHARED: | |
1314 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) | |
1315 | return -EINVAL; | |
1316 | /* | |
1317 | * Ignore pgoff. | |
1318 | */ | |
1319 | pgoff = 0; | |
1320 | vm_flags |= VM_SHARED | VM_MAYSHARE; | |
1321 | break; | |
1322 | case MAP_PRIVATE: | |
1323 | /* | |
1324 | * Set pgoff according to addr for anon_vma. | |
1325 | */ | |
1326 | pgoff = addr >> PAGE_SHIFT; | |
1327 | break; | |
1328 | default: | |
1329 | return -EINVAL; | |
1330 | } | |
1331 | } | |
1332 | ||
1333 | /* | |
1334 | * Set 'VM_NORESERVE' if we should not account for the | |
1335 | * memory use of this mapping. | |
1336 | */ | |
1337 | if (flags & MAP_NORESERVE) { | |
1338 | /* We honor MAP_NORESERVE if allowed to overcommit */ | |
1339 | if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) | |
1340 | vm_flags |= VM_NORESERVE; | |
1341 | ||
1342 | /* hugetlb applies strict overcommit unless MAP_NORESERVE */ | |
1343 | if (file && is_file_hugepages(file)) | |
1344 | vm_flags |= VM_NORESERVE; | |
1345 | } | |
1346 | ||
1347 | addr = mmap_region(file, addr, len, vm_flags, pgoff); | |
1348 | if (!IS_ERR_VALUE(addr) && | |
1349 | ((vm_flags & VM_LOCKED) || | |
1350 | (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) | |
1351 | *populate = len; | |
1352 | return addr; | |
1353 | } | |
1354 | ||
1355 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, | |
1356 | unsigned long, prot, unsigned long, flags, | |
1357 | unsigned long, fd, unsigned long, pgoff) | |
1358 | { | |
1359 | struct file *file = NULL; | |
1360 | unsigned long retval = -EBADF; | |
1361 | ||
1362 | if (!(flags & MAP_ANONYMOUS)) { | |
1363 | audit_mmap_fd(fd, flags); | |
1364 | file = fget(fd); | |
1365 | if (!file) | |
1366 | goto out; | |
1367 | if (is_file_hugepages(file)) | |
1368 | len = ALIGN(len, huge_page_size(hstate_file(file))); | |
1369 | retval = -EINVAL; | |
1370 | if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) | |
1371 | goto out_fput; | |
1372 | } else if (flags & MAP_HUGETLB) { | |
1373 | struct user_struct *user = NULL; | |
1374 | struct hstate *hs; | |
1375 | ||
1376 | hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK); | |
1377 | if (!hs) | |
1378 | return -EINVAL; | |
1379 | ||
1380 | len = ALIGN(len, huge_page_size(hs)); | |
1381 | /* | |
1382 | * VM_NORESERVE is used because the reservations will be | |
1383 | * taken when vm_ops->mmap() is called | |
1384 | * A dummy user value is used because we are not locking | |
1385 | * memory so no accounting is necessary | |
1386 | */ | |
1387 | file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, | |
1388 | VM_NORESERVE, | |
1389 | &user, HUGETLB_ANONHUGE_INODE, | |
1390 | (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); | |
1391 | if (IS_ERR(file)) | |
1392 | return PTR_ERR(file); | |
1393 | } | |
1394 | ||
1395 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); | |
1396 | ||
1397 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); | |
1398 | out_fput: | |
1399 | if (file) | |
1400 | fput(file); | |
1401 | out: | |
1402 | return retval; | |
1403 | } | |
1404 | ||
1405 | #ifdef __ARCH_WANT_SYS_OLD_MMAP | |
1406 | struct mmap_arg_struct { | |
1407 | unsigned long addr; | |
1408 | unsigned long len; | |
1409 | unsigned long prot; | |
1410 | unsigned long flags; | |
1411 | unsigned long fd; | |
1412 | unsigned long offset; | |
1413 | }; | |
1414 | ||
1415 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) | |
1416 | { | |
1417 | struct mmap_arg_struct a; | |
1418 | ||
1419 | if (copy_from_user(&a, arg, sizeof(a))) | |
1420 | return -EFAULT; | |
1421 | if (a.offset & ~PAGE_MASK) | |
1422 | return -EINVAL; | |
1423 | ||
1424 | return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, | |
1425 | a.offset >> PAGE_SHIFT); | |
1426 | } | |
1427 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ | |
1428 | ||
1429 | /* | |
1430 | * Some shared mappigns will want the pages marked read-only | |
1431 | * to track write events. If so, we'll downgrade vm_page_prot | |
1432 | * to the private version (using protection_map[] without the | |
1433 | * VM_SHARED bit). | |
1434 | */ | |
1435 | int vma_wants_writenotify(struct vm_area_struct *vma) | |
1436 | { | |
1437 | vm_flags_t vm_flags = vma->vm_flags; | |
1438 | ||
1439 | /* If it was private or non-writable, the write bit is already clear */ | |
1440 | if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) | |
1441 | return 0; | |
1442 | ||
1443 | /* The backer wishes to know when pages are first written to? */ | |
1444 | if (vma->vm_ops && vma->vm_ops->page_mkwrite) | |
1445 | return 1; | |
1446 | ||
1447 | /* The open routine did something to the protections already? */ | |
1448 | if (pgprot_val(vma->vm_page_prot) != | |
1449 | pgprot_val(vm_get_page_prot(vm_flags))) | |
1450 | return 0; | |
1451 | ||
1452 | /* Specialty mapping? */ | |
1453 | if (vm_flags & VM_PFNMAP) | |
1454 | return 0; | |
1455 | ||
1456 | /* Can the mapping track the dirty pages? */ | |
1457 | return vma->vm_file && vma->vm_file->f_mapping && | |
1458 | mapping_cap_account_dirty(vma->vm_file->f_mapping); | |
1459 | } | |
1460 | ||
1461 | /* | |
1462 | * We account for memory if it's a private writeable mapping, | |
1463 | * not hugepages and VM_NORESERVE wasn't set. | |
1464 | */ | |
1465 | static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) | |
1466 | { | |
1467 | /* | |
1468 | * hugetlb has its own accounting separate from the core VM | |
1469 | * VM_HUGETLB may not be set yet so we cannot check for that flag. | |
1470 | */ | |
1471 | if (file && is_file_hugepages(file)) | |
1472 | return 0; | |
1473 | ||
1474 | return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; | |
1475 | } | |
1476 | ||
1477 | unsigned long mmap_region(struct file *file, unsigned long addr, | |
1478 | unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) | |
1479 | { | |
1480 | struct mm_struct *mm = current->mm; | |
1481 | struct vm_area_struct *vma, *prev; | |
1482 | int error; | |
1483 | struct rb_node **rb_link, *rb_parent; | |
1484 | unsigned long charged = 0; | |
1485 | ||
1486 | /* Check against address space limit. */ | |
1487 | if (!may_expand_vm(mm, len >> PAGE_SHIFT)) { | |
1488 | unsigned long nr_pages; | |
1489 | ||
1490 | /* | |
1491 | * MAP_FIXED may remove pages of mappings that intersects with | |
1492 | * requested mapping. Account for the pages it would unmap. | |
1493 | */ | |
1494 | if (!(vm_flags & MAP_FIXED)) | |
1495 | return -ENOMEM; | |
1496 | ||
1497 | nr_pages = count_vma_pages_range(mm, addr, addr + len); | |
1498 | ||
1499 | if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages)) | |
1500 | return -ENOMEM; | |
1501 | } | |
1502 | ||
1503 | /* Clear old maps */ | |
1504 | error = -ENOMEM; | |
1505 | munmap_back: | |
1506 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) { | |
1507 | if (do_munmap(mm, addr, len)) | |
1508 | return -ENOMEM; | |
1509 | goto munmap_back; | |
1510 | } | |
1511 | ||
1512 | /* | |
1513 | * Private writable mapping: check memory availability | |
1514 | */ | |
1515 | if (accountable_mapping(file, vm_flags)) { | |
1516 | charged = len >> PAGE_SHIFT; | |
1517 | if (security_vm_enough_memory_mm(mm, charged)) | |
1518 | return -ENOMEM; | |
1519 | vm_flags |= VM_ACCOUNT; | |
1520 | } | |
1521 | ||
1522 | /* | |
1523 | * Can we just expand an old mapping? | |
1524 | */ | |
1525 | vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); | |
1526 | if (vma) | |
1527 | goto out; | |
1528 | ||
1529 | /* | |
1530 | * Determine the object being mapped and call the appropriate | |
1531 | * specific mapper. the address has already been validated, but | |
1532 | * not unmapped, but the maps are removed from the list. | |
1533 | */ | |
1534 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
1535 | if (!vma) { | |
1536 | error = -ENOMEM; | |
1537 | goto unacct_error; | |
1538 | } | |
1539 | ||
1540 | vma->vm_mm = mm; | |
1541 | vma->vm_start = addr; | |
1542 | vma->vm_end = addr + len; | |
1543 | vma->vm_flags = vm_flags; | |
1544 | vma->vm_page_prot = vm_get_page_prot(vm_flags); | |
1545 | vma->vm_pgoff = pgoff; | |
1546 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
1547 | ||
1548 | if (file) { | |
1549 | if (vm_flags & VM_DENYWRITE) { | |
1550 | error = deny_write_access(file); | |
1551 | if (error) | |
1552 | goto free_vma; | |
1553 | } | |
1554 | vma->vm_file = get_file(file); | |
1555 | error = file->f_op->mmap(file, vma); | |
1556 | if (error) | |
1557 | goto unmap_and_free_vma; | |
1558 | ||
1559 | /* Can addr have changed?? | |
1560 | * | |
1561 | * Answer: Yes, several device drivers can do it in their | |
1562 | * f_op->mmap method. -DaveM | |
1563 | * Bug: If addr is changed, prev, rb_link, rb_parent should | |
1564 | * be updated for vma_link() | |
1565 | */ | |
1566 | WARN_ON_ONCE(addr != vma->vm_start); | |
1567 | ||
1568 | addr = vma->vm_start; | |
1569 | vm_flags = vma->vm_flags; | |
1570 | } else if (vm_flags & VM_SHARED) { | |
1571 | error = shmem_zero_setup(vma); | |
1572 | if (error) | |
1573 | goto free_vma; | |
1574 | } | |
1575 | ||
1576 | if (vma_wants_writenotify(vma)) { | |
1577 | pgprot_t pprot = vma->vm_page_prot; | |
1578 | ||
1579 | /* Can vma->vm_page_prot have changed?? | |
1580 | * | |
1581 | * Answer: Yes, drivers may have changed it in their | |
1582 | * f_op->mmap method. | |
1583 | * | |
1584 | * Ensures that vmas marked as uncached stay that way. | |
1585 | */ | |
1586 | vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); | |
1587 | if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot))) | |
1588 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); | |
1589 | } | |
1590 | ||
1591 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
1592 | /* Once vma denies write, undo our temporary denial count */ | |
1593 | if (vm_flags & VM_DENYWRITE) | |
1594 | allow_write_access(file); | |
1595 | file = vma->vm_file; | |
1596 | out: | |
1597 | perf_event_mmap(vma); | |
1598 | ||
1599 | vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); | |
1600 | if (vm_flags & VM_LOCKED) { | |
1601 | if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || | |
1602 | vma == get_gate_vma(current->mm))) | |
1603 | mm->locked_vm += (len >> PAGE_SHIFT); | |
1604 | else | |
1605 | vma->vm_flags &= ~VM_LOCKED; | |
1606 | } | |
1607 | ||
1608 | if (file) | |
1609 | uprobe_mmap(vma); | |
1610 | ||
1611 | /* | |
1612 | * New (or expanded) vma always get soft dirty status. | |
1613 | * Otherwise user-space soft-dirty page tracker won't | |
1614 | * be able to distinguish situation when vma area unmapped, | |
1615 | * then new mapped in-place (which must be aimed as | |
1616 | * a completely new data area). | |
1617 | */ | |
1618 | vma->vm_flags |= VM_SOFTDIRTY; | |
1619 | ||
1620 | return addr; | |
1621 | ||
1622 | unmap_and_free_vma: | |
1623 | if (vm_flags & VM_DENYWRITE) | |
1624 | allow_write_access(file); | |
1625 | vma->vm_file = NULL; | |
1626 | fput(file); | |
1627 | ||
1628 | /* Undo any partial mapping done by a device driver. */ | |
1629 | unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); | |
1630 | charged = 0; | |
1631 | free_vma: | |
1632 | kmem_cache_free(vm_area_cachep, vma); | |
1633 | unacct_error: | |
1634 | if (charged) | |
1635 | vm_unacct_memory(charged); | |
1636 | return error; | |
1637 | } | |
1638 | ||
1639 | unsigned long unmapped_area(struct vm_unmapped_area_info *info) | |
1640 | { | |
1641 | /* | |
1642 | * We implement the search by looking for an rbtree node that | |
1643 | * immediately follows a suitable gap. That is, | |
1644 | * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; | |
1645 | * - gap_end = vma->vm_start >= info->low_limit + length; | |
1646 | * - gap_end - gap_start >= length | |
1647 | */ | |
1648 | ||
1649 | struct mm_struct *mm = current->mm; | |
1650 | struct vm_area_struct *vma; | |
1651 | unsigned long length, low_limit, high_limit, gap_start, gap_end; | |
1652 | ||
1653 | /* Adjust search length to account for worst case alignment overhead */ | |
1654 | length = info->length + info->align_mask; | |
1655 | if (length < info->length) | |
1656 | return -ENOMEM; | |
1657 | ||
1658 | /* Adjust search limits by the desired length */ | |
1659 | if (info->high_limit < length) | |
1660 | return -ENOMEM; | |
1661 | high_limit = info->high_limit - length; | |
1662 | ||
1663 | if (info->low_limit > high_limit) | |
1664 | return -ENOMEM; | |
1665 | low_limit = info->low_limit + length; | |
1666 | ||
1667 | /* Check if rbtree root looks promising */ | |
1668 | if (RB_EMPTY_ROOT(&mm->mm_rb)) | |
1669 | goto check_highest; | |
1670 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); | |
1671 | if (vma->rb_subtree_gap < length) | |
1672 | goto check_highest; | |
1673 | ||
1674 | while (true) { | |
1675 | /* Visit left subtree if it looks promising */ | |
1676 | gap_end = vma->vm_start; | |
1677 | if (gap_end >= low_limit && vma->vm_rb.rb_left) { | |
1678 | struct vm_area_struct *left = | |
1679 | rb_entry(vma->vm_rb.rb_left, | |
1680 | struct vm_area_struct, vm_rb); | |
1681 | if (left->rb_subtree_gap >= length) { | |
1682 | vma = left; | |
1683 | continue; | |
1684 | } | |
1685 | } | |
1686 | ||
1687 | gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; | |
1688 | check_current: | |
1689 | /* Check if current node has a suitable gap */ | |
1690 | if (gap_start > high_limit) | |
1691 | return -ENOMEM; | |
1692 | if (gap_end >= low_limit && gap_end - gap_start >= length) | |
1693 | goto found; | |
1694 | ||
1695 | /* Visit right subtree if it looks promising */ | |
1696 | if (vma->vm_rb.rb_right) { | |
1697 | struct vm_area_struct *right = | |
1698 | rb_entry(vma->vm_rb.rb_right, | |
1699 | struct vm_area_struct, vm_rb); | |
1700 | if (right->rb_subtree_gap >= length) { | |
1701 | vma = right; | |
1702 | continue; | |
1703 | } | |
1704 | } | |
1705 | ||
1706 | /* Go back up the rbtree to find next candidate node */ | |
1707 | while (true) { | |
1708 | struct rb_node *prev = &vma->vm_rb; | |
1709 | if (!rb_parent(prev)) | |
1710 | goto check_highest; | |
1711 | vma = rb_entry(rb_parent(prev), | |
1712 | struct vm_area_struct, vm_rb); | |
1713 | if (prev == vma->vm_rb.rb_left) { | |
1714 | gap_start = vma->vm_prev->vm_end; | |
1715 | gap_end = vma->vm_start; | |
1716 | goto check_current; | |
1717 | } | |
1718 | } | |
1719 | } | |
1720 | ||
1721 | check_highest: | |
1722 | /* Check highest gap, which does not precede any rbtree node */ | |
1723 | gap_start = mm->highest_vm_end; | |
1724 | gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ | |
1725 | if (gap_start > high_limit) | |
1726 | return -ENOMEM; | |
1727 | ||
1728 | found: | |
1729 | /* We found a suitable gap. Clip it with the original low_limit. */ | |
1730 | if (gap_start < info->low_limit) | |
1731 | gap_start = info->low_limit; | |
1732 | ||
1733 | /* Adjust gap address to the desired alignment */ | |
1734 | gap_start += (info->align_offset - gap_start) & info->align_mask; | |
1735 | ||
1736 | VM_BUG_ON(gap_start + info->length > info->high_limit); | |
1737 | VM_BUG_ON(gap_start + info->length > gap_end); | |
1738 | return gap_start; | |
1739 | } | |
1740 | ||
1741 | unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) | |
1742 | { | |
1743 | struct mm_struct *mm = current->mm; | |
1744 | struct vm_area_struct *vma; | |
1745 | unsigned long length, low_limit, high_limit, gap_start, gap_end; | |
1746 | ||
1747 | /* Adjust search length to account for worst case alignment overhead */ | |
1748 | length = info->length + info->align_mask; | |
1749 | if (length < info->length) | |
1750 | return -ENOMEM; | |
1751 | ||
1752 | /* | |
1753 | * Adjust search limits by the desired length. | |
1754 | * See implementation comment at top of unmapped_area(). | |
1755 | */ | |
1756 | gap_end = info->high_limit; | |
1757 | if (gap_end < length) | |
1758 | return -ENOMEM; | |
1759 | high_limit = gap_end - length; | |
1760 | ||
1761 | if (info->low_limit > high_limit) | |
1762 | return -ENOMEM; | |
1763 | low_limit = info->low_limit + length; | |
1764 | ||
1765 | /* Check highest gap, which does not precede any rbtree node */ | |
1766 | gap_start = mm->highest_vm_end; | |
1767 | if (gap_start <= high_limit) | |
1768 | goto found_highest; | |
1769 | ||
1770 | /* Check if rbtree root looks promising */ | |
1771 | if (RB_EMPTY_ROOT(&mm->mm_rb)) | |
1772 | return -ENOMEM; | |
1773 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); | |
1774 | if (vma->rb_subtree_gap < length) | |
1775 | return -ENOMEM; | |
1776 | ||
1777 | while (true) { | |
1778 | /* Visit right subtree if it looks promising */ | |
1779 | gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; | |
1780 | if (gap_start <= high_limit && vma->vm_rb.rb_right) { | |
1781 | struct vm_area_struct *right = | |
1782 | rb_entry(vma->vm_rb.rb_right, | |
1783 | struct vm_area_struct, vm_rb); | |
1784 | if (right->rb_subtree_gap >= length) { | |
1785 | vma = right; | |
1786 | continue; | |
1787 | } | |
1788 | } | |
1789 | ||
1790 | check_current: | |
1791 | /* Check if current node has a suitable gap */ | |
1792 | gap_end = vma->vm_start; | |
1793 | if (gap_end < low_limit) | |
1794 | return -ENOMEM; | |
1795 | if (gap_start <= high_limit && gap_end - gap_start >= length) | |
1796 | goto found; | |
1797 | ||
1798 | /* Visit left subtree if it looks promising */ | |
1799 | if (vma->vm_rb.rb_left) { | |
1800 | struct vm_area_struct *left = | |
1801 | rb_entry(vma->vm_rb.rb_left, | |
1802 | struct vm_area_struct, vm_rb); | |
1803 | if (left->rb_subtree_gap >= length) { | |
1804 | vma = left; | |
1805 | continue; | |
1806 | } | |
1807 | } | |
1808 | ||
1809 | /* Go back up the rbtree to find next candidate node */ | |
1810 | while (true) { | |
1811 | struct rb_node *prev = &vma->vm_rb; | |
1812 | if (!rb_parent(prev)) | |
1813 | return -ENOMEM; | |
1814 | vma = rb_entry(rb_parent(prev), | |
1815 | struct vm_area_struct, vm_rb); | |
1816 | if (prev == vma->vm_rb.rb_right) { | |
1817 | gap_start = vma->vm_prev ? | |
1818 | vma->vm_prev->vm_end : 0; | |
1819 | goto check_current; | |
1820 | } | |
1821 | } | |
1822 | } | |
1823 | ||
1824 | found: | |
1825 | /* We found a suitable gap. Clip it with the original high_limit. */ | |
1826 | if (gap_end > info->high_limit) | |
1827 | gap_end = info->high_limit; | |
1828 | ||
1829 | found_highest: | |
1830 | /* Compute highest gap address at the desired alignment */ | |
1831 | gap_end -= info->length; | |
1832 | gap_end -= (gap_end - info->align_offset) & info->align_mask; | |
1833 | ||
1834 | VM_BUG_ON(gap_end < info->low_limit); | |
1835 | VM_BUG_ON(gap_end < gap_start); | |
1836 | return gap_end; | |
1837 | } | |
1838 | ||
1839 | /* Get an address range which is currently unmapped. | |
1840 | * For shmat() with addr=0. | |
1841 | * | |
1842 | * Ugly calling convention alert: | |
1843 | * Return value with the low bits set means error value, | |
1844 | * ie | |
1845 | * if (ret & ~PAGE_MASK) | |
1846 | * error = ret; | |
1847 | * | |
1848 | * This function "knows" that -ENOMEM has the bits set. | |
1849 | */ | |
1850 | #ifndef HAVE_ARCH_UNMAPPED_AREA | |
1851 | unsigned long | |
1852 | arch_get_unmapped_area(struct file *filp, unsigned long addr, | |
1853 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
1854 | { | |
1855 | struct mm_struct *mm = current->mm; | |
1856 | struct vm_area_struct *vma; | |
1857 | struct vm_unmapped_area_info info; | |
1858 | ||
1859 | if (len > TASK_SIZE) | |
1860 | return -ENOMEM; | |
1861 | ||
1862 | if (flags & MAP_FIXED) | |
1863 | return addr; | |
1864 | ||
1865 | if (addr) { | |
1866 | addr = PAGE_ALIGN(addr); | |
1867 | vma = find_vma(mm, addr); | |
1868 | if (TASK_SIZE - len >= addr && | |
1869 | (!vma || addr + len <= vma->vm_start)) | |
1870 | return addr; | |
1871 | } | |
1872 | ||
1873 | info.flags = 0; | |
1874 | info.length = len; | |
1875 | info.low_limit = TASK_UNMAPPED_BASE; | |
1876 | info.high_limit = TASK_SIZE; | |
1877 | info.align_mask = 0; | |
1878 | return vm_unmapped_area(&info); | |
1879 | } | |
1880 | #endif | |
1881 | ||
1882 | /* | |
1883 | * This mmap-allocator allocates new areas top-down from below the | |
1884 | * stack's low limit (the base): | |
1885 | */ | |
1886 | #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN | |
1887 | unsigned long | |
1888 | arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, | |
1889 | const unsigned long len, const unsigned long pgoff, | |
1890 | const unsigned long flags) | |
1891 | { | |
1892 | struct vm_area_struct *vma; | |
1893 | struct mm_struct *mm = current->mm; | |
1894 | unsigned long addr = addr0; | |
1895 | struct vm_unmapped_area_info info; | |
1896 | ||
1897 | /* requested length too big for entire address space */ | |
1898 | if (len > TASK_SIZE) | |
1899 | return -ENOMEM; | |
1900 | ||
1901 | if (flags & MAP_FIXED) | |
1902 | return addr; | |
1903 | ||
1904 | /* requesting a specific address */ | |
1905 | if (addr) { | |
1906 | addr = PAGE_ALIGN(addr); | |
1907 | vma = find_vma(mm, addr); | |
1908 | if (TASK_SIZE - len >= addr && | |
1909 | (!vma || addr + len <= vma->vm_start)) | |
1910 | return addr; | |
1911 | } | |
1912 | ||
1913 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; | |
1914 | info.length = len; | |
1915 | info.low_limit = PAGE_SIZE; | |
1916 | info.high_limit = mm->mmap_base; | |
1917 | info.align_mask = 0; | |
1918 | addr = vm_unmapped_area(&info); | |
1919 | ||
1920 | /* | |
1921 | * A failed mmap() very likely causes application failure, | |
1922 | * so fall back to the bottom-up function here. This scenario | |
1923 | * can happen with large stack limits and large mmap() | |
1924 | * allocations. | |
1925 | */ | |
1926 | if (addr & ~PAGE_MASK) { | |
1927 | VM_BUG_ON(addr != -ENOMEM); | |
1928 | info.flags = 0; | |
1929 | info.low_limit = TASK_UNMAPPED_BASE; | |
1930 | info.high_limit = TASK_SIZE; | |
1931 | addr = vm_unmapped_area(&info); | |
1932 | } | |
1933 | ||
1934 | return addr; | |
1935 | } | |
1936 | #endif | |
1937 | ||
1938 | unsigned long | |
1939 | get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, | |
1940 | unsigned long pgoff, unsigned long flags) | |
1941 | { | |
1942 | unsigned long (*get_area)(struct file *, unsigned long, | |
1943 | unsigned long, unsigned long, unsigned long); | |
1944 | ||
1945 | unsigned long error = arch_mmap_check(addr, len, flags); | |
1946 | if (error) | |
1947 | return error; | |
1948 | ||
1949 | /* Careful about overflows.. */ | |
1950 | if (len > TASK_SIZE) | |
1951 | return -ENOMEM; | |
1952 | ||
1953 | get_area = current->mm->get_unmapped_area; | |
1954 | if (file && file->f_op && file->f_op->get_unmapped_area) | |
1955 | get_area = file->f_op->get_unmapped_area; | |
1956 | addr = get_area(file, addr, len, pgoff, flags); | |
1957 | if (IS_ERR_VALUE(addr)) | |
1958 | return addr; | |
1959 | ||
1960 | if (addr > TASK_SIZE - len) | |
1961 | return -ENOMEM; | |
1962 | if (addr & ~PAGE_MASK) | |
1963 | return -EINVAL; | |
1964 | ||
1965 | addr = arch_rebalance_pgtables(addr, len); | |
1966 | error = security_mmap_addr(addr); | |
1967 | return error ? error : addr; | |
1968 | } | |
1969 | ||
1970 | EXPORT_SYMBOL(get_unmapped_area); | |
1971 | ||
1972 | /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ | |
1973 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) | |
1974 | { | |
1975 | struct vm_area_struct *vma = NULL; | |
1976 | ||
1977 | /* Check the cache first. */ | |
1978 | /* (Cache hit rate is typically around 35%.) */ | |
1979 | vma = ACCESS_ONCE(mm->mmap_cache); | |
1980 | if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { | |
1981 | struct rb_node *rb_node; | |
1982 | ||
1983 | rb_node = mm->mm_rb.rb_node; | |
1984 | vma = NULL; | |
1985 | ||
1986 | while (rb_node) { | |
1987 | struct vm_area_struct *vma_tmp; | |
1988 | ||
1989 | vma_tmp = rb_entry(rb_node, | |
1990 | struct vm_area_struct, vm_rb); | |
1991 | ||
1992 | if (vma_tmp->vm_end > addr) { | |
1993 | vma = vma_tmp; | |
1994 | if (vma_tmp->vm_start <= addr) | |
1995 | break; | |
1996 | rb_node = rb_node->rb_left; | |
1997 | } else | |
1998 | rb_node = rb_node->rb_right; | |
1999 | } | |
2000 | if (vma) | |
2001 | mm->mmap_cache = vma; | |
2002 | } | |
2003 | return vma; | |
2004 | } | |
2005 | ||
2006 | EXPORT_SYMBOL(find_vma); | |
2007 | ||
2008 | /* | |
2009 | * Same as find_vma, but also return a pointer to the previous VMA in *pprev. | |
2010 | */ | |
2011 | struct vm_area_struct * | |
2012 | find_vma_prev(struct mm_struct *mm, unsigned long addr, | |
2013 | struct vm_area_struct **pprev) | |
2014 | { | |
2015 | struct vm_area_struct *vma; | |
2016 | ||
2017 | vma = find_vma(mm, addr); | |
2018 | if (vma) { | |
2019 | *pprev = vma->vm_prev; | |
2020 | } else { | |
2021 | struct rb_node *rb_node = mm->mm_rb.rb_node; | |
2022 | *pprev = NULL; | |
2023 | while (rb_node) { | |
2024 | *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); | |
2025 | rb_node = rb_node->rb_right; | |
2026 | } | |
2027 | } | |
2028 | return vma; | |
2029 | } | |
2030 | ||
2031 | /* | |
2032 | * Verify that the stack growth is acceptable and | |
2033 | * update accounting. This is shared with both the | |
2034 | * grow-up and grow-down cases. | |
2035 | */ | |
2036 | static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) | |
2037 | { | |
2038 | struct mm_struct *mm = vma->vm_mm; | |
2039 | struct rlimit *rlim = current->signal->rlim; | |
2040 | unsigned long new_start; | |
2041 | ||
2042 | /* address space limit tests */ | |
2043 | if (!may_expand_vm(mm, grow)) | |
2044 | return -ENOMEM; | |
2045 | ||
2046 | /* Stack limit test */ | |
2047 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur)) | |
2048 | return -ENOMEM; | |
2049 | ||
2050 | /* mlock limit tests */ | |
2051 | if (vma->vm_flags & VM_LOCKED) { | |
2052 | unsigned long locked; | |
2053 | unsigned long limit; | |
2054 | locked = mm->locked_vm + grow; | |
2055 | limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); | |
2056 | limit >>= PAGE_SHIFT; | |
2057 | if (locked > limit && !capable(CAP_IPC_LOCK)) | |
2058 | return -ENOMEM; | |
2059 | } | |
2060 | ||
2061 | /* Check to ensure the stack will not grow into a hugetlb-only region */ | |
2062 | new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : | |
2063 | vma->vm_end - size; | |
2064 | if (is_hugepage_only_range(vma->vm_mm, new_start, size)) | |
2065 | return -EFAULT; | |
2066 | ||
2067 | /* | |
2068 | * Overcommit.. This must be the final test, as it will | |
2069 | * update security statistics. | |
2070 | */ | |
2071 | if (security_vm_enough_memory_mm(mm, grow)) | |
2072 | return -ENOMEM; | |
2073 | ||
2074 | /* Ok, everything looks good - let it rip */ | |
2075 | if (vma->vm_flags & VM_LOCKED) | |
2076 | mm->locked_vm += grow; | |
2077 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); | |
2078 | return 0; | |
2079 | } | |
2080 | ||
2081 | #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) | |
2082 | /* | |
2083 | * PA-RISC uses this for its stack; IA64 for its Register Backing Store. | |
2084 | * vma is the last one with address > vma->vm_end. Have to extend vma. | |
2085 | */ | |
2086 | int expand_upwards(struct vm_area_struct *vma, unsigned long address) | |
2087 | { | |
2088 | int error; | |
2089 | ||
2090 | if (!(vma->vm_flags & VM_GROWSUP)) | |
2091 | return -EFAULT; | |
2092 | ||
2093 | /* | |
2094 | * We must make sure the anon_vma is allocated | |
2095 | * so that the anon_vma locking is not a noop. | |
2096 | */ | |
2097 | if (unlikely(anon_vma_prepare(vma))) | |
2098 | return -ENOMEM; | |
2099 | vma_lock_anon_vma(vma); | |
2100 | ||
2101 | /* | |
2102 | * vma->vm_start/vm_end cannot change under us because the caller | |
2103 | * is required to hold the mmap_sem in read mode. We need the | |
2104 | * anon_vma lock to serialize against concurrent expand_stacks. | |
2105 | * Also guard against wrapping around to address 0. | |
2106 | */ | |
2107 | if (address < PAGE_ALIGN(address+4)) | |
2108 | address = PAGE_ALIGN(address+4); | |
2109 | else { | |
2110 | vma_unlock_anon_vma(vma); | |
2111 | return -ENOMEM; | |
2112 | } | |
2113 | error = 0; | |
2114 | ||
2115 | /* Somebody else might have raced and expanded it already */ | |
2116 | if (address > vma->vm_end) { | |
2117 | unsigned long size, grow; | |
2118 | ||
2119 | size = address - vma->vm_start; | |
2120 | grow = (address - vma->vm_end) >> PAGE_SHIFT; | |
2121 | ||
2122 | error = -ENOMEM; | |
2123 | if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { | |
2124 | error = acct_stack_growth(vma, size, grow); | |
2125 | if (!error) { | |
2126 | /* | |
2127 | * vma_gap_update() doesn't support concurrent | |
2128 | * updates, but we only hold a shared mmap_sem | |
2129 | * lock here, so we need to protect against | |
2130 | * concurrent vma expansions. | |
2131 | * vma_lock_anon_vma() doesn't help here, as | |
2132 | * we don't guarantee that all growable vmas | |
2133 | * in a mm share the same root anon vma. | |
2134 | * So, we reuse mm->page_table_lock to guard | |
2135 | * against concurrent vma expansions. | |
2136 | */ | |
2137 | spin_lock(&vma->vm_mm->page_table_lock); | |
2138 | anon_vma_interval_tree_pre_update_vma(vma); | |
2139 | vma->vm_end = address; | |
2140 | anon_vma_interval_tree_post_update_vma(vma); | |
2141 | if (vma->vm_next) | |
2142 | vma_gap_update(vma->vm_next); | |
2143 | else | |
2144 | vma->vm_mm->highest_vm_end = address; | |
2145 | spin_unlock(&vma->vm_mm->page_table_lock); | |
2146 | ||
2147 | perf_event_mmap(vma); | |
2148 | } | |
2149 | } | |
2150 | } | |
2151 | vma_unlock_anon_vma(vma); | |
2152 | khugepaged_enter_vma_merge(vma); | |
2153 | validate_mm(vma->vm_mm); | |
2154 | return error; | |
2155 | } | |
2156 | #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ | |
2157 | ||
2158 | /* | |
2159 | * vma is the first one with address < vma->vm_start. Have to extend vma. | |
2160 | */ | |
2161 | int expand_downwards(struct vm_area_struct *vma, | |
2162 | unsigned long address) | |
2163 | { | |
2164 | int error; | |
2165 | ||
2166 | /* | |
2167 | * We must make sure the anon_vma is allocated | |
2168 | * so that the anon_vma locking is not a noop. | |
2169 | */ | |
2170 | if (unlikely(anon_vma_prepare(vma))) | |
2171 | return -ENOMEM; | |
2172 | ||
2173 | address &= PAGE_MASK; | |
2174 | error = security_mmap_addr(address); | |
2175 | if (error) | |
2176 | return error; | |
2177 | ||
2178 | vma_lock_anon_vma(vma); | |
2179 | ||
2180 | /* | |
2181 | * vma->vm_start/vm_end cannot change under us because the caller | |
2182 | * is required to hold the mmap_sem in read mode. We need the | |
2183 | * anon_vma lock to serialize against concurrent expand_stacks. | |
2184 | */ | |
2185 | ||
2186 | /* Somebody else might have raced and expanded it already */ | |
2187 | if (address < vma->vm_start) { | |
2188 | unsigned long size, grow; | |
2189 | ||
2190 | size = vma->vm_end - address; | |
2191 | grow = (vma->vm_start - address) >> PAGE_SHIFT; | |
2192 | ||
2193 | error = -ENOMEM; | |
2194 | if (grow <= vma->vm_pgoff) { | |
2195 | error = acct_stack_growth(vma, size, grow); | |
2196 | if (!error) { | |
2197 | /* | |
2198 | * vma_gap_update() doesn't support concurrent | |
2199 | * updates, but we only hold a shared mmap_sem | |
2200 | * lock here, so we need to protect against | |
2201 | * concurrent vma expansions. | |
2202 | * vma_lock_anon_vma() doesn't help here, as | |
2203 | * we don't guarantee that all growable vmas | |
2204 | * in a mm share the same root anon vma. | |
2205 | * So, we reuse mm->page_table_lock to guard | |
2206 | * against concurrent vma expansions. | |
2207 | */ | |
2208 | spin_lock(&vma->vm_mm->page_table_lock); | |
2209 | anon_vma_interval_tree_pre_update_vma(vma); | |
2210 | vma->vm_start = address; | |
2211 | vma->vm_pgoff -= grow; | |
2212 | anon_vma_interval_tree_post_update_vma(vma); | |
2213 | vma_gap_update(vma); | |
2214 | spin_unlock(&vma->vm_mm->page_table_lock); | |
2215 | ||
2216 | perf_event_mmap(vma); | |
2217 | } | |
2218 | } | |
2219 | } | |
2220 | vma_unlock_anon_vma(vma); | |
2221 | khugepaged_enter_vma_merge(vma); | |
2222 | validate_mm(vma->vm_mm); | |
2223 | return error; | |
2224 | } | |
2225 | ||
2226 | /* | |
2227 | * Note how expand_stack() refuses to expand the stack all the way to | |
2228 | * abut the next virtual mapping, *unless* that mapping itself is also | |
2229 | * a stack mapping. We want to leave room for a guard page, after all | |
2230 | * (the guard page itself is not added here, that is done by the | |
2231 | * actual page faulting logic) | |
2232 | * | |
2233 | * This matches the behavior of the guard page logic (see mm/memory.c: | |
2234 | * check_stack_guard_page()), which only allows the guard page to be | |
2235 | * removed under these circumstances. | |
2236 | */ | |
2237 | #ifdef CONFIG_STACK_GROWSUP | |
2238 | int expand_stack(struct vm_area_struct *vma, unsigned long address) | |
2239 | { | |
2240 | struct vm_area_struct *next; | |
2241 | ||
2242 | address &= PAGE_MASK; | |
2243 | next = vma->vm_next; | |
2244 | if (next && next->vm_start == address + PAGE_SIZE) { | |
2245 | if (!(next->vm_flags & VM_GROWSUP)) | |
2246 | return -ENOMEM; | |
2247 | } | |
2248 | return expand_upwards(vma, address); | |
2249 | } | |
2250 | ||
2251 | struct vm_area_struct * | |
2252 | find_extend_vma(struct mm_struct *mm, unsigned long addr) | |
2253 | { | |
2254 | struct vm_area_struct *vma, *prev; | |
2255 | ||
2256 | addr &= PAGE_MASK; | |
2257 | vma = find_vma_prev(mm, addr, &prev); | |
2258 | if (vma && (vma->vm_start <= addr)) | |
2259 | return vma; | |
2260 | if (!prev || expand_stack(prev, addr)) | |
2261 | return NULL; | |
2262 | if (prev->vm_flags & VM_LOCKED) | |
2263 | __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL); | |
2264 | return prev; | |
2265 | } | |
2266 | #else | |
2267 | int expand_stack(struct vm_area_struct *vma, unsigned long address) | |
2268 | { | |
2269 | struct vm_area_struct *prev; | |
2270 | ||
2271 | address &= PAGE_MASK; | |
2272 | prev = vma->vm_prev; | |
2273 | if (prev && prev->vm_end == address) { | |
2274 | if (!(prev->vm_flags & VM_GROWSDOWN)) | |
2275 | return -ENOMEM; | |
2276 | } | |
2277 | return expand_downwards(vma, address); | |
2278 | } | |
2279 | ||
2280 | struct vm_area_struct * | |
2281 | find_extend_vma(struct mm_struct * mm, unsigned long addr) | |
2282 | { | |
2283 | struct vm_area_struct * vma; | |
2284 | unsigned long start; | |
2285 | ||
2286 | addr &= PAGE_MASK; | |
2287 | vma = find_vma(mm,addr); | |
2288 | if (!vma) | |
2289 | return NULL; | |
2290 | if (vma->vm_start <= addr) | |
2291 | return vma; | |
2292 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
2293 | return NULL; | |
2294 | start = vma->vm_start; | |
2295 | if (expand_stack(vma, addr)) | |
2296 | return NULL; | |
2297 | if (vma->vm_flags & VM_LOCKED) | |
2298 | __mlock_vma_pages_range(vma, addr, start, NULL); | |
2299 | return vma; | |
2300 | } | |
2301 | #endif | |
2302 | ||
2303 | /* | |
2304 | * Ok - we have the memory areas we should free on the vma list, | |
2305 | * so release them, and do the vma updates. | |
2306 | * | |
2307 | * Called with the mm semaphore held. | |
2308 | */ | |
2309 | static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) | |
2310 | { | |
2311 | unsigned long nr_accounted = 0; | |
2312 | ||
2313 | /* Update high watermark before we lower total_vm */ | |
2314 | update_hiwater_vm(mm); | |
2315 | do { | |
2316 | long nrpages = vma_pages(vma); | |
2317 | ||
2318 | if (vma->vm_flags & VM_ACCOUNT) | |
2319 | nr_accounted += nrpages; | |
2320 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); | |
2321 | vma = remove_vma(vma); | |
2322 | } while (vma); | |
2323 | vm_unacct_memory(nr_accounted); | |
2324 | validate_mm(mm); | |
2325 | } | |
2326 | ||
2327 | /* | |
2328 | * Get rid of page table information in the indicated region. | |
2329 | * | |
2330 | * Called with the mm semaphore held. | |
2331 | */ | |
2332 | static void unmap_region(struct mm_struct *mm, | |
2333 | struct vm_area_struct *vma, struct vm_area_struct *prev, | |
2334 | unsigned long start, unsigned long end) | |
2335 | { | |
2336 | struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; | |
2337 | struct mmu_gather tlb; | |
2338 | ||
2339 | lru_add_drain(); | |
2340 | tlb_gather_mmu(&tlb, mm, start, end); | |
2341 | update_hiwater_rss(mm); | |
2342 | unmap_vmas(&tlb, vma, start, end); | |
2343 | free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, | |
2344 | next ? next->vm_start : USER_PGTABLES_CEILING); | |
2345 | tlb_finish_mmu(&tlb, start, end); | |
2346 | } | |
2347 | ||
2348 | /* | |
2349 | * Create a list of vma's touched by the unmap, removing them from the mm's | |
2350 | * vma list as we go.. | |
2351 | */ | |
2352 | static void | |
2353 | detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, | |
2354 | struct vm_area_struct *prev, unsigned long end) | |
2355 | { | |
2356 | struct vm_area_struct **insertion_point; | |
2357 | struct vm_area_struct *tail_vma = NULL; | |
2358 | ||
2359 | insertion_point = (prev ? &prev->vm_next : &mm->mmap); | |
2360 | vma->vm_prev = NULL; | |
2361 | do { | |
2362 | vma_rb_erase(vma, &mm->mm_rb); | |
2363 | mm->map_count--; | |
2364 | tail_vma = vma; | |
2365 | vma = vma->vm_next; | |
2366 | } while (vma && vma->vm_start < end); | |
2367 | *insertion_point = vma; | |
2368 | if (vma) { | |
2369 | vma->vm_prev = prev; | |
2370 | vma_gap_update(vma); | |
2371 | } else | |
2372 | mm->highest_vm_end = prev ? prev->vm_end : 0; | |
2373 | tail_vma->vm_next = NULL; | |
2374 | mm->mmap_cache = NULL; /* Kill the cache. */ | |
2375 | } | |
2376 | ||
2377 | /* | |
2378 | * __split_vma() bypasses sysctl_max_map_count checking. We use this on the | |
2379 | * munmap path where it doesn't make sense to fail. | |
2380 | */ | |
2381 | static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma, | |
2382 | unsigned long addr, int new_below) | |
2383 | { | |
2384 | struct vm_area_struct *new; | |
2385 | int err = -ENOMEM; | |
2386 | ||
2387 | if (is_vm_hugetlb_page(vma) && (addr & | |
2388 | ~(huge_page_mask(hstate_vma(vma))))) | |
2389 | return -EINVAL; | |
2390 | ||
2391 | new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
2392 | if (!new) | |
2393 | goto out_err; | |
2394 | ||
2395 | /* most fields are the same, copy all, and then fixup */ | |
2396 | *new = *vma; | |
2397 | ||
2398 | INIT_LIST_HEAD(&new->anon_vma_chain); | |
2399 | ||
2400 | if (new_below) | |
2401 | new->vm_end = addr; | |
2402 | else { | |
2403 | new->vm_start = addr; | |
2404 | new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); | |
2405 | } | |
2406 | ||
2407 | err = vma_dup_policy(vma, new); | |
2408 | if (err) | |
2409 | goto out_free_vma; | |
2410 | ||
2411 | if (anon_vma_clone(new, vma)) | |
2412 | goto out_free_mpol; | |
2413 | ||
2414 | if (new->vm_file) | |
2415 | get_file(new->vm_file); | |
2416 | ||
2417 | if (new->vm_ops && new->vm_ops->open) | |
2418 | new->vm_ops->open(new); | |
2419 | ||
2420 | if (new_below) | |
2421 | err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + | |
2422 | ((addr - new->vm_start) >> PAGE_SHIFT), new); | |
2423 | else | |
2424 | err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); | |
2425 | ||
2426 | /* Success. */ | |
2427 | if (!err) | |
2428 | return 0; | |
2429 | ||
2430 | /* Clean everything up if vma_adjust failed. */ | |
2431 | if (new->vm_ops && new->vm_ops->close) | |
2432 | new->vm_ops->close(new); | |
2433 | if (new->vm_file) | |
2434 | fput(new->vm_file); | |
2435 | unlink_anon_vmas(new); | |
2436 | out_free_mpol: | |
2437 | mpol_put(vma_policy(new)); | |
2438 | out_free_vma: | |
2439 | kmem_cache_free(vm_area_cachep, new); | |
2440 | out_err: | |
2441 | return err; | |
2442 | } | |
2443 | ||
2444 | /* | |
2445 | * Split a vma into two pieces at address 'addr', a new vma is allocated | |
2446 | * either for the first part or the tail. | |
2447 | */ | |
2448 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, | |
2449 | unsigned long addr, int new_below) | |
2450 | { | |
2451 | if (mm->map_count >= sysctl_max_map_count) | |
2452 | return -ENOMEM; | |
2453 | ||
2454 | return __split_vma(mm, vma, addr, new_below); | |
2455 | } | |
2456 | ||
2457 | /* Munmap is split into 2 main parts -- this part which finds | |
2458 | * what needs doing, and the areas themselves, which do the | |
2459 | * work. This now handles partial unmappings. | |
2460 | * Jeremy Fitzhardinge <jeremy@goop.org> | |
2461 | */ | |
2462 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) | |
2463 | { | |
2464 | unsigned long end; | |
2465 | struct vm_area_struct *vma, *prev, *last; | |
2466 | ||
2467 | if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) | |
2468 | return -EINVAL; | |
2469 | ||
2470 | if ((len = PAGE_ALIGN(len)) == 0) | |
2471 | return -EINVAL; | |
2472 | ||
2473 | /* Find the first overlapping VMA */ | |
2474 | vma = find_vma(mm, start); | |
2475 | if (!vma) | |
2476 | return 0; | |
2477 | prev = vma->vm_prev; | |
2478 | /* we have start < vma->vm_end */ | |
2479 | ||
2480 | /* if it doesn't overlap, we have nothing.. */ | |
2481 | end = start + len; | |
2482 | if (vma->vm_start >= end) | |
2483 | return 0; | |
2484 | ||
2485 | /* | |
2486 | * If we need to split any vma, do it now to save pain later. | |
2487 | * | |
2488 | * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially | |
2489 | * unmapped vm_area_struct will remain in use: so lower split_vma | |
2490 | * places tmp vma above, and higher split_vma places tmp vma below. | |
2491 | */ | |
2492 | if (start > vma->vm_start) { | |
2493 | int error; | |
2494 | ||
2495 | /* | |
2496 | * Make sure that map_count on return from munmap() will | |
2497 | * not exceed its limit; but let map_count go just above | |
2498 | * its limit temporarily, to help free resources as expected. | |
2499 | */ | |
2500 | if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) | |
2501 | return -ENOMEM; | |
2502 | ||
2503 | error = __split_vma(mm, vma, start, 0); | |
2504 | if (error) | |
2505 | return error; | |
2506 | prev = vma; | |
2507 | } | |
2508 | ||
2509 | /* Does it split the last one? */ | |
2510 | last = find_vma(mm, end); | |
2511 | if (last && end > last->vm_start) { | |
2512 | int error = __split_vma(mm, last, end, 1); | |
2513 | if (error) | |
2514 | return error; | |
2515 | } | |
2516 | vma = prev? prev->vm_next: mm->mmap; | |
2517 | ||
2518 | /* | |
2519 | * unlock any mlock()ed ranges before detaching vmas | |
2520 | */ | |
2521 | if (mm->locked_vm) { | |
2522 | struct vm_area_struct *tmp = vma; | |
2523 | while (tmp && tmp->vm_start < end) { | |
2524 | if (tmp->vm_flags & VM_LOCKED) { | |
2525 | mm->locked_vm -= vma_pages(tmp); | |
2526 | munlock_vma_pages_all(tmp); | |
2527 | } | |
2528 | tmp = tmp->vm_next; | |
2529 | } | |
2530 | } | |
2531 | ||
2532 | /* | |
2533 | * Remove the vma's, and unmap the actual pages | |
2534 | */ | |
2535 | detach_vmas_to_be_unmapped(mm, vma, prev, end); | |
2536 | unmap_region(mm, vma, prev, start, end); | |
2537 | ||
2538 | /* Fix up all other VM information */ | |
2539 | remove_vma_list(mm, vma); | |
2540 | ||
2541 | return 0; | |
2542 | } | |
2543 | ||
2544 | int vm_munmap(unsigned long start, size_t len) | |
2545 | { | |
2546 | int ret; | |
2547 | struct mm_struct *mm = current->mm; | |
2548 | ||
2549 | down_write(&mm->mmap_sem); | |
2550 | ret = do_munmap(mm, start, len); | |
2551 | up_write(&mm->mmap_sem); | |
2552 | return ret; | |
2553 | } | |
2554 | EXPORT_SYMBOL(vm_munmap); | |
2555 | ||
2556 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) | |
2557 | { | |
2558 | profile_munmap(addr); | |
2559 | return vm_munmap(addr, len); | |
2560 | } | |
2561 | ||
2562 | static inline void verify_mm_writelocked(struct mm_struct *mm) | |
2563 | { | |
2564 | #ifdef CONFIG_DEBUG_VM | |
2565 | if (unlikely(down_read_trylock(&mm->mmap_sem))) { | |
2566 | WARN_ON(1); | |
2567 | up_read(&mm->mmap_sem); | |
2568 | } | |
2569 | #endif | |
2570 | } | |
2571 | ||
2572 | /* | |
2573 | * this is really a simplified "do_mmap". it only handles | |
2574 | * anonymous maps. eventually we may be able to do some | |
2575 | * brk-specific accounting here. | |
2576 | */ | |
2577 | static unsigned long do_brk(unsigned long addr, unsigned long len) | |
2578 | { | |
2579 | struct mm_struct * mm = current->mm; | |
2580 | struct vm_area_struct * vma, * prev; | |
2581 | unsigned long flags; | |
2582 | struct rb_node ** rb_link, * rb_parent; | |
2583 | pgoff_t pgoff = addr >> PAGE_SHIFT; | |
2584 | int error; | |
2585 | ||
2586 | len = PAGE_ALIGN(len); | |
2587 | if (!len) | |
2588 | return addr; | |
2589 | ||
2590 | flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; | |
2591 | ||
2592 | error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); | |
2593 | if (error & ~PAGE_MASK) | |
2594 | return error; | |
2595 | ||
2596 | /* | |
2597 | * mlock MCL_FUTURE? | |
2598 | */ | |
2599 | if (mm->def_flags & VM_LOCKED) { | |
2600 | unsigned long locked, lock_limit; | |
2601 | locked = len >> PAGE_SHIFT; | |
2602 | locked += mm->locked_vm; | |
2603 | lock_limit = rlimit(RLIMIT_MEMLOCK); | |
2604 | lock_limit >>= PAGE_SHIFT; | |
2605 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
2606 | return -EAGAIN; | |
2607 | } | |
2608 | ||
2609 | /* | |
2610 | * mm->mmap_sem is required to protect against another thread | |
2611 | * changing the mappings in case we sleep. | |
2612 | */ | |
2613 | verify_mm_writelocked(mm); | |
2614 | ||
2615 | /* | |
2616 | * Clear old maps. this also does some error checking for us | |
2617 | */ | |
2618 | munmap_back: | |
2619 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) { | |
2620 | if (do_munmap(mm, addr, len)) | |
2621 | return -ENOMEM; | |
2622 | goto munmap_back; | |
2623 | } | |
2624 | ||
2625 | /* Check against address space limits *after* clearing old maps... */ | |
2626 | if (!may_expand_vm(mm, len >> PAGE_SHIFT)) | |
2627 | return -ENOMEM; | |
2628 | ||
2629 | if (mm->map_count > sysctl_max_map_count) | |
2630 | return -ENOMEM; | |
2631 | ||
2632 | if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) | |
2633 | return -ENOMEM; | |
2634 | ||
2635 | /* Can we just expand an old private anonymous mapping? */ | |
2636 | vma = vma_merge(mm, prev, addr, addr + len, flags, | |
2637 | NULL, NULL, pgoff, NULL); | |
2638 | if (vma) | |
2639 | goto out; | |
2640 | ||
2641 | /* | |
2642 | * create a vma struct for an anonymous mapping | |
2643 | */ | |
2644 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
2645 | if (!vma) { | |
2646 | vm_unacct_memory(len >> PAGE_SHIFT); | |
2647 | return -ENOMEM; | |
2648 | } | |
2649 | ||
2650 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
2651 | vma->vm_mm = mm; | |
2652 | vma->vm_start = addr; | |
2653 | vma->vm_end = addr + len; | |
2654 | vma->vm_pgoff = pgoff; | |
2655 | vma->vm_flags = flags; | |
2656 | vma->vm_page_prot = vm_get_page_prot(flags); | |
2657 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
2658 | out: | |
2659 | perf_event_mmap(vma); | |
2660 | mm->total_vm += len >> PAGE_SHIFT; | |
2661 | if (flags & VM_LOCKED) | |
2662 | mm->locked_vm += (len >> PAGE_SHIFT); | |
2663 | vma->vm_flags |= VM_SOFTDIRTY; | |
2664 | return addr; | |
2665 | } | |
2666 | ||
2667 | unsigned long vm_brk(unsigned long addr, unsigned long len) | |
2668 | { | |
2669 | struct mm_struct *mm = current->mm; | |
2670 | unsigned long ret; | |
2671 | bool populate; | |
2672 | ||
2673 | down_write(&mm->mmap_sem); | |
2674 | ret = do_brk(addr, len); | |
2675 | populate = ((mm->def_flags & VM_LOCKED) != 0); | |
2676 | up_write(&mm->mmap_sem); | |
2677 | if (populate) | |
2678 | mm_populate(addr, len); | |
2679 | return ret; | |
2680 | } | |
2681 | EXPORT_SYMBOL(vm_brk); | |
2682 | ||
2683 | /* Release all mmaps. */ | |
2684 | void exit_mmap(struct mm_struct *mm) | |
2685 | { | |
2686 | struct mmu_gather tlb; | |
2687 | struct vm_area_struct *vma; | |
2688 | unsigned long nr_accounted = 0; | |
2689 | ||
2690 | /* mm's last user has gone, and its about to be pulled down */ | |
2691 | mmu_notifier_release(mm); | |
2692 | ||
2693 | if (mm->locked_vm) { | |
2694 | vma = mm->mmap; | |
2695 | while (vma) { | |
2696 | if (vma->vm_flags & VM_LOCKED) | |
2697 | munlock_vma_pages_all(vma); | |
2698 | vma = vma->vm_next; | |
2699 | } | |
2700 | } | |
2701 | ||
2702 | arch_exit_mmap(mm); | |
2703 | ||
2704 | vma = mm->mmap; | |
2705 | if (!vma) /* Can happen if dup_mmap() received an OOM */ | |
2706 | return; | |
2707 | ||
2708 | lru_add_drain(); | |
2709 | flush_cache_mm(mm); | |
2710 | tlb_gather_mmu(&tlb, mm, 0, -1); | |
2711 | /* update_hiwater_rss(mm) here? but nobody should be looking */ | |
2712 | /* Use -1 here to ensure all VMAs in the mm are unmapped */ | |
2713 | unmap_vmas(&tlb, vma, 0, -1); | |
2714 | ||
2715 | free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); | |
2716 | tlb_finish_mmu(&tlb, 0, -1); | |
2717 | ||
2718 | /* | |
2719 | * Walk the list again, actually closing and freeing it, | |
2720 | * with preemption enabled, without holding any MM locks. | |
2721 | */ | |
2722 | while (vma) { | |
2723 | if (vma->vm_flags & VM_ACCOUNT) | |
2724 | nr_accounted += vma_pages(vma); | |
2725 | vma = remove_vma(vma); | |
2726 | } | |
2727 | vm_unacct_memory(nr_accounted); | |
2728 | ||
2729 | WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); | |
2730 | } | |
2731 | ||
2732 | /* Insert vm structure into process list sorted by address | |
2733 | * and into the inode's i_mmap tree. If vm_file is non-NULL | |
2734 | * then i_mmap_mutex is taken here. | |
2735 | */ | |
2736 | int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) | |
2737 | { | |
2738 | struct vm_area_struct *prev; | |
2739 | struct rb_node **rb_link, *rb_parent; | |
2740 | ||
2741 | /* | |
2742 | * The vm_pgoff of a purely anonymous vma should be irrelevant | |
2743 | * until its first write fault, when page's anon_vma and index | |
2744 | * are set. But now set the vm_pgoff it will almost certainly | |
2745 | * end up with (unless mremap moves it elsewhere before that | |
2746 | * first wfault), so /proc/pid/maps tells a consistent story. | |
2747 | * | |
2748 | * By setting it to reflect the virtual start address of the | |
2749 | * vma, merges and splits can happen in a seamless way, just | |
2750 | * using the existing file pgoff checks and manipulations. | |
2751 | * Similarly in do_mmap_pgoff and in do_brk. | |
2752 | */ | |
2753 | if (!vma->vm_file) { | |
2754 | BUG_ON(vma->anon_vma); | |
2755 | vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; | |
2756 | } | |
2757 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, | |
2758 | &prev, &rb_link, &rb_parent)) | |
2759 | return -ENOMEM; | |
2760 | if ((vma->vm_flags & VM_ACCOUNT) && | |
2761 | security_vm_enough_memory_mm(mm, vma_pages(vma))) | |
2762 | return -ENOMEM; | |
2763 | ||
2764 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
2765 | return 0; | |
2766 | } | |
2767 | ||
2768 | /* | |
2769 | * Copy the vma structure to a new location in the same mm, | |
2770 | * prior to moving page table entries, to effect an mremap move. | |
2771 | */ | |
2772 | struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, | |
2773 | unsigned long addr, unsigned long len, pgoff_t pgoff, | |
2774 | bool *need_rmap_locks) | |
2775 | { | |
2776 | struct vm_area_struct *vma = *vmap; | |
2777 | unsigned long vma_start = vma->vm_start; | |
2778 | struct mm_struct *mm = vma->vm_mm; | |
2779 | struct vm_area_struct *new_vma, *prev; | |
2780 | struct rb_node **rb_link, *rb_parent; | |
2781 | bool faulted_in_anon_vma = true; | |
2782 | ||
2783 | /* | |
2784 | * If anonymous vma has not yet been faulted, update new pgoff | |
2785 | * to match new location, to increase its chance of merging. | |
2786 | */ | |
2787 | if (unlikely(!vma->vm_file && !vma->anon_vma)) { | |
2788 | pgoff = addr >> PAGE_SHIFT; | |
2789 | faulted_in_anon_vma = false; | |
2790 | } | |
2791 | ||
2792 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) | |
2793 | return NULL; /* should never get here */ | |
2794 | new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, | |
2795 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); | |
2796 | if (new_vma) { | |
2797 | /* | |
2798 | * Source vma may have been merged into new_vma | |
2799 | */ | |
2800 | if (unlikely(vma_start >= new_vma->vm_start && | |
2801 | vma_start < new_vma->vm_end)) { | |
2802 | /* | |
2803 | * The only way we can get a vma_merge with | |
2804 | * self during an mremap is if the vma hasn't | |
2805 | * been faulted in yet and we were allowed to | |
2806 | * reset the dst vma->vm_pgoff to the | |
2807 | * destination address of the mremap to allow | |
2808 | * the merge to happen. mremap must change the | |
2809 | * vm_pgoff linearity between src and dst vmas | |
2810 | * (in turn preventing a vma_merge) to be | |
2811 | * safe. It is only safe to keep the vm_pgoff | |
2812 | * linear if there are no pages mapped yet. | |
2813 | */ | |
2814 | VM_BUG_ON(faulted_in_anon_vma); | |
2815 | *vmap = vma = new_vma; | |
2816 | } | |
2817 | *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); | |
2818 | } else { | |
2819 | new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
2820 | if (new_vma) { | |
2821 | *new_vma = *vma; | |
2822 | new_vma->vm_start = addr; | |
2823 | new_vma->vm_end = addr + len; | |
2824 | new_vma->vm_pgoff = pgoff; | |
2825 | if (vma_dup_policy(vma, new_vma)) | |
2826 | goto out_free_vma; | |
2827 | INIT_LIST_HEAD(&new_vma->anon_vma_chain); | |
2828 | if (anon_vma_clone(new_vma, vma)) | |
2829 | goto out_free_mempol; | |
2830 | if (new_vma->vm_file) | |
2831 | get_file(new_vma->vm_file); | |
2832 | if (new_vma->vm_ops && new_vma->vm_ops->open) | |
2833 | new_vma->vm_ops->open(new_vma); | |
2834 | vma_link(mm, new_vma, prev, rb_link, rb_parent); | |
2835 | *need_rmap_locks = false; | |
2836 | } | |
2837 | } | |
2838 | return new_vma; | |
2839 | ||
2840 | out_free_mempol: | |
2841 | mpol_put(vma_policy(new_vma)); | |
2842 | out_free_vma: | |
2843 | kmem_cache_free(vm_area_cachep, new_vma); | |
2844 | return NULL; | |
2845 | } | |
2846 | ||
2847 | /* | |
2848 | * Return true if the calling process may expand its vm space by the passed | |
2849 | * number of pages | |
2850 | */ | |
2851 | int may_expand_vm(struct mm_struct *mm, unsigned long npages) | |
2852 | { | |
2853 | unsigned long cur = mm->total_vm; /* pages */ | |
2854 | unsigned long lim; | |
2855 | ||
2856 | lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT; | |
2857 | ||
2858 | if (cur + npages > lim) | |
2859 | return 0; | |
2860 | return 1; | |
2861 | } | |
2862 | ||
2863 | ||
2864 | static int special_mapping_fault(struct vm_area_struct *vma, | |
2865 | struct vm_fault *vmf) | |
2866 | { | |
2867 | pgoff_t pgoff; | |
2868 | struct page **pages; | |
2869 | ||
2870 | /* | |
2871 | * special mappings have no vm_file, and in that case, the mm | |
2872 | * uses vm_pgoff internally. So we have to subtract it from here. | |
2873 | * We are allowed to do this because we are the mm; do not copy | |
2874 | * this code into drivers! | |
2875 | */ | |
2876 | pgoff = vmf->pgoff - vma->vm_pgoff; | |
2877 | ||
2878 | for (pages = vma->vm_private_data; pgoff && *pages; ++pages) | |
2879 | pgoff--; | |
2880 | ||
2881 | if (*pages) { | |
2882 | struct page *page = *pages; | |
2883 | get_page(page); | |
2884 | vmf->page = page; | |
2885 | return 0; | |
2886 | } | |
2887 | ||
2888 | return VM_FAULT_SIGBUS; | |
2889 | } | |
2890 | ||
2891 | /* | |
2892 | * Having a close hook prevents vma merging regardless of flags. | |
2893 | */ | |
2894 | static void special_mapping_close(struct vm_area_struct *vma) | |
2895 | { | |
2896 | } | |
2897 | ||
2898 | static const struct vm_operations_struct special_mapping_vmops = { | |
2899 | .close = special_mapping_close, | |
2900 | .fault = special_mapping_fault, | |
2901 | }; | |
2902 | ||
2903 | /* | |
2904 | * Called with mm->mmap_sem held for writing. | |
2905 | * Insert a new vma covering the given region, with the given flags. | |
2906 | * Its pages are supplied by the given array of struct page *. | |
2907 | * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. | |
2908 | * The region past the last page supplied will always produce SIGBUS. | |
2909 | * The array pointer and the pages it points to are assumed to stay alive | |
2910 | * for as long as this mapping might exist. | |
2911 | */ | |
2912 | int install_special_mapping(struct mm_struct *mm, | |
2913 | unsigned long addr, unsigned long len, | |
2914 | unsigned long vm_flags, struct page **pages) | |
2915 | { | |
2916 | int ret; | |
2917 | struct vm_area_struct *vma; | |
2918 | ||
2919 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); | |
2920 | if (unlikely(vma == NULL)) | |
2921 | return -ENOMEM; | |
2922 | ||
2923 | INIT_LIST_HEAD(&vma->anon_vma_chain); | |
2924 | vma->vm_mm = mm; | |
2925 | vma->vm_start = addr; | |
2926 | vma->vm_end = addr + len; | |
2927 | ||
2928 | vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY; | |
2929 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); | |
2930 | ||
2931 | vma->vm_ops = &special_mapping_vmops; | |
2932 | vma->vm_private_data = pages; | |
2933 | ||
2934 | ret = insert_vm_struct(mm, vma); | |
2935 | if (ret) | |
2936 | goto out; | |
2937 | ||
2938 | mm->total_vm += len >> PAGE_SHIFT; | |
2939 | ||
2940 | perf_event_mmap(vma); | |
2941 | ||
2942 | return 0; | |
2943 | ||
2944 | out: | |
2945 | kmem_cache_free(vm_area_cachep, vma); | |
2946 | return ret; | |
2947 | } | |
2948 | ||
2949 | static DEFINE_MUTEX(mm_all_locks_mutex); | |
2950 | ||
2951 | static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) | |
2952 | { | |
2953 | if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { | |
2954 | /* | |
2955 | * The LSB of head.next can't change from under us | |
2956 | * because we hold the mm_all_locks_mutex. | |
2957 | */ | |
2958 | down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); | |
2959 | /* | |
2960 | * We can safely modify head.next after taking the | |
2961 | * anon_vma->root->rwsem. If some other vma in this mm shares | |
2962 | * the same anon_vma we won't take it again. | |
2963 | * | |
2964 | * No need of atomic instructions here, head.next | |
2965 | * can't change from under us thanks to the | |
2966 | * anon_vma->root->rwsem. | |
2967 | */ | |
2968 | if (__test_and_set_bit(0, (unsigned long *) | |
2969 | &anon_vma->root->rb_root.rb_node)) | |
2970 | BUG(); | |
2971 | } | |
2972 | } | |
2973 | ||
2974 | static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) | |
2975 | { | |
2976 | if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { | |
2977 | /* | |
2978 | * AS_MM_ALL_LOCKS can't change from under us because | |
2979 | * we hold the mm_all_locks_mutex. | |
2980 | * | |
2981 | * Operations on ->flags have to be atomic because | |
2982 | * even if AS_MM_ALL_LOCKS is stable thanks to the | |
2983 | * mm_all_locks_mutex, there may be other cpus | |
2984 | * changing other bitflags in parallel to us. | |
2985 | */ | |
2986 | if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) | |
2987 | BUG(); | |
2988 | mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem); | |
2989 | } | |
2990 | } | |
2991 | ||
2992 | /* | |
2993 | * This operation locks against the VM for all pte/vma/mm related | |
2994 | * operations that could ever happen on a certain mm. This includes | |
2995 | * vmtruncate, try_to_unmap, and all page faults. | |
2996 | * | |
2997 | * The caller must take the mmap_sem in write mode before calling | |
2998 | * mm_take_all_locks(). The caller isn't allowed to release the | |
2999 | * mmap_sem until mm_drop_all_locks() returns. | |
3000 | * | |
3001 | * mmap_sem in write mode is required in order to block all operations | |
3002 | * that could modify pagetables and free pages without need of | |
3003 | * altering the vma layout (for example populate_range() with | |
3004 | * nonlinear vmas). It's also needed in write mode to avoid new | |
3005 | * anon_vmas to be associated with existing vmas. | |
3006 | * | |
3007 | * A single task can't take more than one mm_take_all_locks() in a row | |
3008 | * or it would deadlock. | |
3009 | * | |
3010 | * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in | |
3011 | * mapping->flags avoid to take the same lock twice, if more than one | |
3012 | * vma in this mm is backed by the same anon_vma or address_space. | |
3013 | * | |
3014 | * We can take all the locks in random order because the VM code | |
3015 | * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never | |
3016 | * takes more than one of them in a row. Secondly we're protected | |
3017 | * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. | |
3018 | * | |
3019 | * mm_take_all_locks() and mm_drop_all_locks are expensive operations | |
3020 | * that may have to take thousand of locks. | |
3021 | * | |
3022 | * mm_take_all_locks() can fail if it's interrupted by signals. | |
3023 | */ | |
3024 | int mm_take_all_locks(struct mm_struct *mm) | |
3025 | { | |
3026 | struct vm_area_struct *vma; | |
3027 | struct anon_vma_chain *avc; | |
3028 | ||
3029 | BUG_ON(down_read_trylock(&mm->mmap_sem)); | |
3030 | ||
3031 | mutex_lock(&mm_all_locks_mutex); | |
3032 | ||
3033 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3034 | if (signal_pending(current)) | |
3035 | goto out_unlock; | |
3036 | if (vma->vm_file && vma->vm_file->f_mapping) | |
3037 | vm_lock_mapping(mm, vma->vm_file->f_mapping); | |
3038 | } | |
3039 | ||
3040 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3041 | if (signal_pending(current)) | |
3042 | goto out_unlock; | |
3043 | if (vma->anon_vma) | |
3044 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
3045 | vm_lock_anon_vma(mm, avc->anon_vma); | |
3046 | } | |
3047 | ||
3048 | return 0; | |
3049 | ||
3050 | out_unlock: | |
3051 | mm_drop_all_locks(mm); | |
3052 | return -EINTR; | |
3053 | } | |
3054 | ||
3055 | static void vm_unlock_anon_vma(struct anon_vma *anon_vma) | |
3056 | { | |
3057 | if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { | |
3058 | /* | |
3059 | * The LSB of head.next can't change to 0 from under | |
3060 | * us because we hold the mm_all_locks_mutex. | |
3061 | * | |
3062 | * We must however clear the bitflag before unlocking | |
3063 | * the vma so the users using the anon_vma->rb_root will | |
3064 | * never see our bitflag. | |
3065 | * | |
3066 | * No need of atomic instructions here, head.next | |
3067 | * can't change from under us until we release the | |
3068 | * anon_vma->root->rwsem. | |
3069 | */ | |
3070 | if (!__test_and_clear_bit(0, (unsigned long *) | |
3071 | &anon_vma->root->rb_root.rb_node)) | |
3072 | BUG(); | |
3073 | anon_vma_unlock_write(anon_vma); | |
3074 | } | |
3075 | } | |
3076 | ||
3077 | static void vm_unlock_mapping(struct address_space *mapping) | |
3078 | { | |
3079 | if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { | |
3080 | /* | |
3081 | * AS_MM_ALL_LOCKS can't change to 0 from under us | |
3082 | * because we hold the mm_all_locks_mutex. | |
3083 | */ | |
3084 | mutex_unlock(&mapping->i_mmap_mutex); | |
3085 | if (!test_and_clear_bit(AS_MM_ALL_LOCKS, | |
3086 | &mapping->flags)) | |
3087 | BUG(); | |
3088 | } | |
3089 | } | |
3090 | ||
3091 | /* | |
3092 | * The mmap_sem cannot be released by the caller until | |
3093 | * mm_drop_all_locks() returns. | |
3094 | */ | |
3095 | void mm_drop_all_locks(struct mm_struct *mm) | |
3096 | { | |
3097 | struct vm_area_struct *vma; | |
3098 | struct anon_vma_chain *avc; | |
3099 | ||
3100 | BUG_ON(down_read_trylock(&mm->mmap_sem)); | |
3101 | BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); | |
3102 | ||
3103 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3104 | if (vma->anon_vma) | |
3105 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
3106 | vm_unlock_anon_vma(avc->anon_vma); | |
3107 | if (vma->vm_file && vma->vm_file->f_mapping) | |
3108 | vm_unlock_mapping(vma->vm_file->f_mapping); | |
3109 | } | |
3110 | ||
3111 | mutex_unlock(&mm_all_locks_mutex); | |
3112 | } | |
3113 | ||
3114 | /* | |
3115 | * initialise the VMA slab | |
3116 | */ | |
3117 | void __init mmap_init(void) | |
3118 | { | |
3119 | int ret; | |
3120 | ||
3121 | ret = percpu_counter_init(&vm_committed_as, 0); | |
3122 | VM_BUG_ON(ret); | |
3123 | } | |
3124 | ||
3125 | /* | |
3126 | * Initialise sysctl_user_reserve_kbytes. | |
3127 | * | |
3128 | * This is intended to prevent a user from starting a single memory hogging | |
3129 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER | |
3130 | * mode. | |
3131 | * | |
3132 | * The default value is min(3% of free memory, 128MB) | |
3133 | * 128MB is enough to recover with sshd/login, bash, and top/kill. | |
3134 | */ | |
3135 | static int init_user_reserve(void) | |
3136 | { | |
3137 | unsigned long free_kbytes; | |
3138 | ||
3139 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3140 | ||
3141 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); | |
3142 | return 0; | |
3143 | } | |
3144 | module_init(init_user_reserve) | |
3145 | ||
3146 | /* | |
3147 | * Initialise sysctl_admin_reserve_kbytes. | |
3148 | * | |
3149 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin | |
3150 | * to log in and kill a memory hogging process. | |
3151 | * | |
3152 | * Systems with more than 256MB will reserve 8MB, enough to recover | |
3153 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will | |
3154 | * only reserve 3% of free pages by default. | |
3155 | */ | |
3156 | static int init_admin_reserve(void) | |
3157 | { | |
3158 | unsigned long free_kbytes; | |
3159 | ||
3160 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3161 | ||
3162 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); | |
3163 | return 0; | |
3164 | } | |
3165 | module_init(init_admin_reserve) | |
3166 | ||
3167 | /* | |
3168 | * Reinititalise user and admin reserves if memory is added or removed. | |
3169 | * | |
3170 | * The default user reserve max is 128MB, and the default max for the | |
3171 | * admin reserve is 8MB. These are usually, but not always, enough to | |
3172 | * enable recovery from a memory hogging process using login/sshd, a shell, | |
3173 | * and tools like top. It may make sense to increase or even disable the | |
3174 | * reserve depending on the existence of swap or variations in the recovery | |
3175 | * tools. So, the admin may have changed them. | |
3176 | * | |
3177 | * If memory is added and the reserves have been eliminated or increased above | |
3178 | * the default max, then we'll trust the admin. | |
3179 | * | |
3180 | * If memory is removed and there isn't enough free memory, then we | |
3181 | * need to reset the reserves. | |
3182 | * | |
3183 | * Otherwise keep the reserve set by the admin. | |
3184 | */ | |
3185 | static int reserve_mem_notifier(struct notifier_block *nb, | |
3186 | unsigned long action, void *data) | |
3187 | { | |
3188 | unsigned long tmp, free_kbytes; | |
3189 | ||
3190 | switch (action) { | |
3191 | case MEM_ONLINE: | |
3192 | /* Default max is 128MB. Leave alone if modified by operator. */ | |
3193 | tmp = sysctl_user_reserve_kbytes; | |
3194 | if (0 < tmp && tmp < (1UL << 17)) | |
3195 | init_user_reserve(); | |
3196 | ||
3197 | /* Default max is 8MB. Leave alone if modified by operator. */ | |
3198 | tmp = sysctl_admin_reserve_kbytes; | |
3199 | if (0 < tmp && tmp < (1UL << 13)) | |
3200 | init_admin_reserve(); | |
3201 | ||
3202 | break; | |
3203 | case MEM_OFFLINE: | |
3204 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3205 | ||
3206 | if (sysctl_user_reserve_kbytes > free_kbytes) { | |
3207 | init_user_reserve(); | |
3208 | pr_info("vm.user_reserve_kbytes reset to %lu\n", | |
3209 | sysctl_user_reserve_kbytes); | |
3210 | } | |
3211 | ||
3212 | if (sysctl_admin_reserve_kbytes > free_kbytes) { | |
3213 | init_admin_reserve(); | |
3214 | pr_info("vm.admin_reserve_kbytes reset to %lu\n", | |
3215 | sysctl_admin_reserve_kbytes); | |
3216 | } | |
3217 | break; | |
3218 | default: | |
3219 | break; | |
3220 | } | |
3221 | return NOTIFY_OK; | |
3222 | } | |
3223 | ||
3224 | static struct notifier_block reserve_mem_nb = { | |
3225 | .notifier_call = reserve_mem_notifier, | |
3226 | }; | |
3227 | ||
3228 | static int __meminit init_reserve_notifier(void) | |
3229 | { | |
3230 | if (register_hotmemory_notifier(&reserve_mem_nb)) | |
3231 | printk("Failed registering memory add/remove notifier for admin reserve"); | |
3232 | ||
3233 | return 0; | |
3234 | } | |
3235 | module_init(init_reserve_notifier) |