]>
Commit | Line | Data |
---|---|---|
1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * mm/mmap.c | |
4 | * | |
5 | * Written by obz. | |
6 | * | |
7 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> | |
8 | */ | |
9 | ||
10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
11 | ||
12 | #include <linux/kernel.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/backing-dev.h> | |
15 | #include <linux/mm.h> | |
16 | #include <linux/vmacache.h> | |
17 | #include <linux/shm.h> | |
18 | #include <linux/mman.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/swap.h> | |
21 | #include <linux/syscalls.h> | |
22 | #include <linux/capability.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/personality.h> | |
27 | #include <linux/security.h> | |
28 | #include <linux/hugetlb.h> | |
29 | #include <linux/shmem_fs.h> | |
30 | #include <linux/profile.h> | |
31 | #include <linux/export.h> | |
32 | #include <linux/mount.h> | |
33 | #include <linux/mempolicy.h> | |
34 | #include <linux/rmap.h> | |
35 | #include <linux/mmu_notifier.h> | |
36 | #include <linux/mmdebug.h> | |
37 | #include <linux/perf_event.h> | |
38 | #include <linux/audit.h> | |
39 | #include <linux/khugepaged.h> | |
40 | #include <linux/uprobes.h> | |
41 | #include <linux/rbtree_augmented.h> | |
42 | #include <linux/notifier.h> | |
43 | #include <linux/memory.h> | |
44 | #include <linux/printk.h> | |
45 | #include <linux/userfaultfd_k.h> | |
46 | #include <linux/moduleparam.h> | |
47 | #include <linux/pkeys.h> | |
48 | #include <linux/oom.h> | |
49 | #include <linux/sched/mm.h> | |
50 | ||
51 | #include <linux/uaccess.h> | |
52 | #include <asm/cacheflush.h> | |
53 | #include <asm/tlb.h> | |
54 | #include <asm/mmu_context.h> | |
55 | ||
56 | #include "internal.h" | |
57 | ||
58 | #ifndef arch_mmap_check | |
59 | #define arch_mmap_check(addr, len, flags) (0) | |
60 | #endif | |
61 | ||
62 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS | |
63 | const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; | |
64 | const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; | |
65 | int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; | |
66 | #endif | |
67 | #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS | |
68 | const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; | |
69 | const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; | |
70 | int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; | |
71 | #endif | |
72 | ||
73 | static bool ignore_rlimit_data; | |
74 | core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); | |
75 | ||
76 | static void unmap_region(struct mm_struct *mm, | |
77 | struct vm_area_struct *vma, struct vm_area_struct *prev, | |
78 | unsigned long start, unsigned long end); | |
79 | ||
80 | /* description of effects of mapping type and prot in current implementation. | |
81 | * this is due to the limited x86 page protection hardware. The expected | |
82 | * behavior is in parens: | |
83 | * | |
84 | * map_type prot | |
85 | * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC | |
86 | * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes | |
87 | * w: (no) no w: (no) no w: (yes) yes w: (no) no | |
88 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes | |
89 | * | |
90 | * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes | |
91 | * w: (no) no w: (no) no w: (copy) copy w: (no) no | |
92 | * x: (no) no x: (no) yes x: (no) yes x: (yes) yes | |
93 | * | |
94 | * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and | |
95 | * MAP_PRIVATE: | |
96 | * r: (no) no | |
97 | * w: (no) no | |
98 | * x: (yes) yes | |
99 | */ | |
100 | pgprot_t protection_map[16] __ro_after_init = { | |
101 | __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, | |
102 | __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 | |
103 | }; | |
104 | ||
105 | #ifndef CONFIG_ARCH_HAS_FILTER_PGPROT | |
106 | static inline pgprot_t arch_filter_pgprot(pgprot_t prot) | |
107 | { | |
108 | return prot; | |
109 | } | |
110 | #endif | |
111 | ||
112 | pgprot_t vm_get_page_prot(unsigned long vm_flags) | |
113 | { | |
114 | pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags & | |
115 | (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | | |
116 | pgprot_val(arch_vm_get_page_prot(vm_flags))); | |
117 | ||
118 | return arch_filter_pgprot(ret); | |
119 | } | |
120 | EXPORT_SYMBOL(vm_get_page_prot); | |
121 | ||
122 | static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) | |
123 | { | |
124 | return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); | |
125 | } | |
126 | ||
127 | /* Update vma->vm_page_prot to reflect vma->vm_flags. */ | |
128 | void vma_set_page_prot(struct vm_area_struct *vma) | |
129 | { | |
130 | unsigned long vm_flags = vma->vm_flags; | |
131 | pgprot_t vm_page_prot; | |
132 | ||
133 | vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); | |
134 | if (vma_wants_writenotify(vma, vm_page_prot)) { | |
135 | vm_flags &= ~VM_SHARED; | |
136 | vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags); | |
137 | } | |
138 | /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */ | |
139 | WRITE_ONCE(vma->vm_page_prot, vm_page_prot); | |
140 | } | |
141 | ||
142 | /* | |
143 | * Requires inode->i_mapping->i_mmap_rwsem | |
144 | */ | |
145 | static void __remove_shared_vm_struct(struct vm_area_struct *vma, | |
146 | struct file *file, struct address_space *mapping) | |
147 | { | |
148 | if (vma->vm_flags & VM_DENYWRITE) | |
149 | atomic_inc(&file_inode(file)->i_writecount); | |
150 | if (vma->vm_flags & VM_SHARED) | |
151 | mapping_unmap_writable(mapping); | |
152 | ||
153 | flush_dcache_mmap_lock(mapping); | |
154 | vma_interval_tree_remove(vma, &mapping->i_mmap); | |
155 | flush_dcache_mmap_unlock(mapping); | |
156 | } | |
157 | ||
158 | /* | |
159 | * Unlink a file-based vm structure from its interval tree, to hide | |
160 | * vma from rmap and vmtruncate before freeing its page tables. | |
161 | */ | |
162 | void unlink_file_vma(struct vm_area_struct *vma) | |
163 | { | |
164 | struct file *file = vma->vm_file; | |
165 | ||
166 | if (file) { | |
167 | struct address_space *mapping = file->f_mapping; | |
168 | i_mmap_lock_write(mapping); | |
169 | __remove_shared_vm_struct(vma, file, mapping); | |
170 | i_mmap_unlock_write(mapping); | |
171 | } | |
172 | } | |
173 | ||
174 | /* | |
175 | * Close a vm structure and free it, returning the next. | |
176 | */ | |
177 | static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) | |
178 | { | |
179 | struct vm_area_struct *next = vma->vm_next; | |
180 | ||
181 | might_sleep(); | |
182 | if (vma->vm_ops && vma->vm_ops->close) | |
183 | vma->vm_ops->close(vma); | |
184 | if (vma->vm_file) | |
185 | fput(vma->vm_file); | |
186 | mpol_put(vma_policy(vma)); | |
187 | vm_area_free(vma); | |
188 | return next; | |
189 | } | |
190 | ||
191 | static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, | |
192 | struct list_head *uf); | |
193 | SYSCALL_DEFINE1(brk, unsigned long, brk) | |
194 | { | |
195 | unsigned long retval; | |
196 | unsigned long newbrk, oldbrk, origbrk; | |
197 | struct mm_struct *mm = current->mm; | |
198 | struct vm_area_struct *next; | |
199 | unsigned long min_brk; | |
200 | bool populate; | |
201 | bool downgraded = false; | |
202 | LIST_HEAD(uf); | |
203 | ||
204 | if (down_write_killable(&mm->mmap_sem)) | |
205 | return -EINTR; | |
206 | ||
207 | origbrk = mm->brk; | |
208 | ||
209 | #ifdef CONFIG_COMPAT_BRK | |
210 | /* | |
211 | * CONFIG_COMPAT_BRK can still be overridden by setting | |
212 | * randomize_va_space to 2, which will still cause mm->start_brk | |
213 | * to be arbitrarily shifted | |
214 | */ | |
215 | if (current->brk_randomized) | |
216 | min_brk = mm->start_brk; | |
217 | else | |
218 | min_brk = mm->end_data; | |
219 | #else | |
220 | min_brk = mm->start_brk; | |
221 | #endif | |
222 | if (brk < min_brk) | |
223 | goto out; | |
224 | ||
225 | /* | |
226 | * Check against rlimit here. If this check is done later after the test | |
227 | * of oldbrk with newbrk then it can escape the test and let the data | |
228 | * segment grow beyond its set limit the in case where the limit is | |
229 | * not page aligned -Ram Gupta | |
230 | */ | |
231 | if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, | |
232 | mm->end_data, mm->start_data)) | |
233 | goto out; | |
234 | ||
235 | newbrk = PAGE_ALIGN(brk); | |
236 | oldbrk = PAGE_ALIGN(mm->brk); | |
237 | if (oldbrk == newbrk) { | |
238 | mm->brk = brk; | |
239 | goto success; | |
240 | } | |
241 | ||
242 | /* | |
243 | * Always allow shrinking brk. | |
244 | * __do_munmap() may downgrade mmap_sem to read. | |
245 | */ | |
246 | if (brk <= mm->brk) { | |
247 | int ret; | |
248 | ||
249 | /* | |
250 | * mm->brk must to be protected by write mmap_sem so update it | |
251 | * before downgrading mmap_sem. When __do_munmap() fails, | |
252 | * mm->brk will be restored from origbrk. | |
253 | */ | |
254 | mm->brk = brk; | |
255 | ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true); | |
256 | if (ret < 0) { | |
257 | mm->brk = origbrk; | |
258 | goto out; | |
259 | } else if (ret == 1) { | |
260 | downgraded = true; | |
261 | } | |
262 | goto success; | |
263 | } | |
264 | ||
265 | /* Check against existing mmap mappings. */ | |
266 | next = find_vma(mm, oldbrk); | |
267 | if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) | |
268 | goto out; | |
269 | ||
270 | /* Ok, looks good - let it rip. */ | |
271 | if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0) | |
272 | goto out; | |
273 | mm->brk = brk; | |
274 | ||
275 | success: | |
276 | populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; | |
277 | if (downgraded) | |
278 | up_read(&mm->mmap_sem); | |
279 | else | |
280 | up_write(&mm->mmap_sem); | |
281 | userfaultfd_unmap_complete(mm, &uf); | |
282 | if (populate) | |
283 | mm_populate(oldbrk, newbrk - oldbrk); | |
284 | return brk; | |
285 | ||
286 | out: | |
287 | retval = origbrk; | |
288 | up_write(&mm->mmap_sem); | |
289 | return retval; | |
290 | } | |
291 | ||
292 | static long vma_compute_subtree_gap(struct vm_area_struct *vma) | |
293 | { | |
294 | unsigned long max, prev_end, subtree_gap; | |
295 | ||
296 | /* | |
297 | * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we | |
298 | * allow two stack_guard_gaps between them here, and when choosing | |
299 | * an unmapped area; whereas when expanding we only require one. | |
300 | * That's a little inconsistent, but keeps the code here simpler. | |
301 | */ | |
302 | max = vm_start_gap(vma); | |
303 | if (vma->vm_prev) { | |
304 | prev_end = vm_end_gap(vma->vm_prev); | |
305 | if (max > prev_end) | |
306 | max -= prev_end; | |
307 | else | |
308 | max = 0; | |
309 | } | |
310 | if (vma->vm_rb.rb_left) { | |
311 | subtree_gap = rb_entry(vma->vm_rb.rb_left, | |
312 | struct vm_area_struct, vm_rb)->rb_subtree_gap; | |
313 | if (subtree_gap > max) | |
314 | max = subtree_gap; | |
315 | } | |
316 | if (vma->vm_rb.rb_right) { | |
317 | subtree_gap = rb_entry(vma->vm_rb.rb_right, | |
318 | struct vm_area_struct, vm_rb)->rb_subtree_gap; | |
319 | if (subtree_gap > max) | |
320 | max = subtree_gap; | |
321 | } | |
322 | return max; | |
323 | } | |
324 | ||
325 | #ifdef CONFIG_DEBUG_VM_RB | |
326 | static int browse_rb(struct mm_struct *mm) | |
327 | { | |
328 | struct rb_root *root = &mm->mm_rb; | |
329 | int i = 0, j, bug = 0; | |
330 | struct rb_node *nd, *pn = NULL; | |
331 | unsigned long prev = 0, pend = 0; | |
332 | ||
333 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { | |
334 | struct vm_area_struct *vma; | |
335 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); | |
336 | if (vma->vm_start < prev) { | |
337 | pr_emerg("vm_start %lx < prev %lx\n", | |
338 | vma->vm_start, prev); | |
339 | bug = 1; | |
340 | } | |
341 | if (vma->vm_start < pend) { | |
342 | pr_emerg("vm_start %lx < pend %lx\n", | |
343 | vma->vm_start, pend); | |
344 | bug = 1; | |
345 | } | |
346 | if (vma->vm_start > vma->vm_end) { | |
347 | pr_emerg("vm_start %lx > vm_end %lx\n", | |
348 | vma->vm_start, vma->vm_end); | |
349 | bug = 1; | |
350 | } | |
351 | spin_lock(&mm->page_table_lock); | |
352 | if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { | |
353 | pr_emerg("free gap %lx, correct %lx\n", | |
354 | vma->rb_subtree_gap, | |
355 | vma_compute_subtree_gap(vma)); | |
356 | bug = 1; | |
357 | } | |
358 | spin_unlock(&mm->page_table_lock); | |
359 | i++; | |
360 | pn = nd; | |
361 | prev = vma->vm_start; | |
362 | pend = vma->vm_end; | |
363 | } | |
364 | j = 0; | |
365 | for (nd = pn; nd; nd = rb_prev(nd)) | |
366 | j++; | |
367 | if (i != j) { | |
368 | pr_emerg("backwards %d, forwards %d\n", j, i); | |
369 | bug = 1; | |
370 | } | |
371 | return bug ? -1 : i; | |
372 | } | |
373 | ||
374 | static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) | |
375 | { | |
376 | struct rb_node *nd; | |
377 | ||
378 | for (nd = rb_first(root); nd; nd = rb_next(nd)) { | |
379 | struct vm_area_struct *vma; | |
380 | vma = rb_entry(nd, struct vm_area_struct, vm_rb); | |
381 | VM_BUG_ON_VMA(vma != ignore && | |
382 | vma->rb_subtree_gap != vma_compute_subtree_gap(vma), | |
383 | vma); | |
384 | } | |
385 | } | |
386 | ||
387 | static void validate_mm(struct mm_struct *mm) | |
388 | { | |
389 | int bug = 0; | |
390 | int i = 0; | |
391 | unsigned long highest_address = 0; | |
392 | struct vm_area_struct *vma = mm->mmap; | |
393 | ||
394 | while (vma) { | |
395 | struct anon_vma *anon_vma = vma->anon_vma; | |
396 | struct anon_vma_chain *avc; | |
397 | ||
398 | if (anon_vma) { | |
399 | anon_vma_lock_read(anon_vma); | |
400 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
401 | anon_vma_interval_tree_verify(avc); | |
402 | anon_vma_unlock_read(anon_vma); | |
403 | } | |
404 | ||
405 | highest_address = vm_end_gap(vma); | |
406 | vma = vma->vm_next; | |
407 | i++; | |
408 | } | |
409 | if (i != mm->map_count) { | |
410 | pr_emerg("map_count %d vm_next %d\n", mm->map_count, i); | |
411 | bug = 1; | |
412 | } | |
413 | if (highest_address != mm->highest_vm_end) { | |
414 | pr_emerg("mm->highest_vm_end %lx, found %lx\n", | |
415 | mm->highest_vm_end, highest_address); | |
416 | bug = 1; | |
417 | } | |
418 | i = browse_rb(mm); | |
419 | if (i != mm->map_count) { | |
420 | if (i != -1) | |
421 | pr_emerg("map_count %d rb %d\n", mm->map_count, i); | |
422 | bug = 1; | |
423 | } | |
424 | VM_BUG_ON_MM(bug, mm); | |
425 | } | |
426 | #else | |
427 | #define validate_mm_rb(root, ignore) do { } while (0) | |
428 | #define validate_mm(mm) do { } while (0) | |
429 | #endif | |
430 | ||
431 | RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, | |
432 | unsigned long, rb_subtree_gap, vma_compute_subtree_gap) | |
433 | ||
434 | /* | |
435 | * Update augmented rbtree rb_subtree_gap values after vma->vm_start or | |
436 | * vma->vm_prev->vm_end values changed, without modifying the vma's position | |
437 | * in the rbtree. | |
438 | */ | |
439 | static void vma_gap_update(struct vm_area_struct *vma) | |
440 | { | |
441 | /* | |
442 | * As it turns out, RB_DECLARE_CALLBACKS() already created a callback | |
443 | * function that does exactly what we want. | |
444 | */ | |
445 | vma_gap_callbacks_propagate(&vma->vm_rb, NULL); | |
446 | } | |
447 | ||
448 | static inline void vma_rb_insert(struct vm_area_struct *vma, | |
449 | struct rb_root *root) | |
450 | { | |
451 | /* All rb_subtree_gap values must be consistent prior to insertion */ | |
452 | validate_mm_rb(root, NULL); | |
453 | ||
454 | rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); | |
455 | } | |
456 | ||
457 | static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) | |
458 | { | |
459 | /* | |
460 | * Note rb_erase_augmented is a fairly large inline function, | |
461 | * so make sure we instantiate it only once with our desired | |
462 | * augmented rbtree callbacks. | |
463 | */ | |
464 | rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); | |
465 | } | |
466 | ||
467 | static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma, | |
468 | struct rb_root *root, | |
469 | struct vm_area_struct *ignore) | |
470 | { | |
471 | /* | |
472 | * All rb_subtree_gap values must be consistent prior to erase, | |
473 | * with the possible exception of the "next" vma being erased if | |
474 | * next->vm_start was reduced. | |
475 | */ | |
476 | validate_mm_rb(root, ignore); | |
477 | ||
478 | __vma_rb_erase(vma, root); | |
479 | } | |
480 | ||
481 | static __always_inline void vma_rb_erase(struct vm_area_struct *vma, | |
482 | struct rb_root *root) | |
483 | { | |
484 | /* | |
485 | * All rb_subtree_gap values must be consistent prior to erase, | |
486 | * with the possible exception of the vma being erased. | |
487 | */ | |
488 | validate_mm_rb(root, vma); | |
489 | ||
490 | __vma_rb_erase(vma, root); | |
491 | } | |
492 | ||
493 | /* | |
494 | * vma has some anon_vma assigned, and is already inserted on that | |
495 | * anon_vma's interval trees. | |
496 | * | |
497 | * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the | |
498 | * vma must be removed from the anon_vma's interval trees using | |
499 | * anon_vma_interval_tree_pre_update_vma(). | |
500 | * | |
501 | * After the update, the vma will be reinserted using | |
502 | * anon_vma_interval_tree_post_update_vma(). | |
503 | * | |
504 | * The entire update must be protected by exclusive mmap_sem and by | |
505 | * the root anon_vma's mutex. | |
506 | */ | |
507 | static inline void | |
508 | anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) | |
509 | { | |
510 | struct anon_vma_chain *avc; | |
511 | ||
512 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
513 | anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); | |
514 | } | |
515 | ||
516 | static inline void | |
517 | anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) | |
518 | { | |
519 | struct anon_vma_chain *avc; | |
520 | ||
521 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
522 | anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); | |
523 | } | |
524 | ||
525 | static int find_vma_links(struct mm_struct *mm, unsigned long addr, | |
526 | unsigned long end, struct vm_area_struct **pprev, | |
527 | struct rb_node ***rb_link, struct rb_node **rb_parent) | |
528 | { | |
529 | struct rb_node **__rb_link, *__rb_parent, *rb_prev; | |
530 | ||
531 | __rb_link = &mm->mm_rb.rb_node; | |
532 | rb_prev = __rb_parent = NULL; | |
533 | ||
534 | while (*__rb_link) { | |
535 | struct vm_area_struct *vma_tmp; | |
536 | ||
537 | __rb_parent = *__rb_link; | |
538 | vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); | |
539 | ||
540 | if (vma_tmp->vm_end > addr) { | |
541 | /* Fail if an existing vma overlaps the area */ | |
542 | if (vma_tmp->vm_start < end) | |
543 | return -ENOMEM; | |
544 | __rb_link = &__rb_parent->rb_left; | |
545 | } else { | |
546 | rb_prev = __rb_parent; | |
547 | __rb_link = &__rb_parent->rb_right; | |
548 | } | |
549 | } | |
550 | ||
551 | *pprev = NULL; | |
552 | if (rb_prev) | |
553 | *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); | |
554 | *rb_link = __rb_link; | |
555 | *rb_parent = __rb_parent; | |
556 | return 0; | |
557 | } | |
558 | ||
559 | static unsigned long count_vma_pages_range(struct mm_struct *mm, | |
560 | unsigned long addr, unsigned long end) | |
561 | { | |
562 | unsigned long nr_pages = 0; | |
563 | struct vm_area_struct *vma; | |
564 | ||
565 | /* Find first overlaping mapping */ | |
566 | vma = find_vma_intersection(mm, addr, end); | |
567 | if (!vma) | |
568 | return 0; | |
569 | ||
570 | nr_pages = (min(end, vma->vm_end) - | |
571 | max(addr, vma->vm_start)) >> PAGE_SHIFT; | |
572 | ||
573 | /* Iterate over the rest of the overlaps */ | |
574 | for (vma = vma->vm_next; vma; vma = vma->vm_next) { | |
575 | unsigned long overlap_len; | |
576 | ||
577 | if (vma->vm_start > end) | |
578 | break; | |
579 | ||
580 | overlap_len = min(end, vma->vm_end) - vma->vm_start; | |
581 | nr_pages += overlap_len >> PAGE_SHIFT; | |
582 | } | |
583 | ||
584 | return nr_pages; | |
585 | } | |
586 | ||
587 | void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, | |
588 | struct rb_node **rb_link, struct rb_node *rb_parent) | |
589 | { | |
590 | /* Update tracking information for the gap following the new vma. */ | |
591 | if (vma->vm_next) | |
592 | vma_gap_update(vma->vm_next); | |
593 | else | |
594 | mm->highest_vm_end = vm_end_gap(vma); | |
595 | ||
596 | /* | |
597 | * vma->vm_prev wasn't known when we followed the rbtree to find the | |
598 | * correct insertion point for that vma. As a result, we could not | |
599 | * update the vma vm_rb parents rb_subtree_gap values on the way down. | |
600 | * So, we first insert the vma with a zero rb_subtree_gap value | |
601 | * (to be consistent with what we did on the way down), and then | |
602 | * immediately update the gap to the correct value. Finally we | |
603 | * rebalance the rbtree after all augmented values have been set. | |
604 | */ | |
605 | rb_link_node(&vma->vm_rb, rb_parent, rb_link); | |
606 | vma->rb_subtree_gap = 0; | |
607 | vma_gap_update(vma); | |
608 | vma_rb_insert(vma, &mm->mm_rb); | |
609 | } | |
610 | ||
611 | static void __vma_link_file(struct vm_area_struct *vma) | |
612 | { | |
613 | struct file *file; | |
614 | ||
615 | file = vma->vm_file; | |
616 | if (file) { | |
617 | struct address_space *mapping = file->f_mapping; | |
618 | ||
619 | if (vma->vm_flags & VM_DENYWRITE) | |
620 | atomic_dec(&file_inode(file)->i_writecount); | |
621 | if (vma->vm_flags & VM_SHARED) | |
622 | atomic_inc(&mapping->i_mmap_writable); | |
623 | ||
624 | flush_dcache_mmap_lock(mapping); | |
625 | vma_interval_tree_insert(vma, &mapping->i_mmap); | |
626 | flush_dcache_mmap_unlock(mapping); | |
627 | } | |
628 | } | |
629 | ||
630 | static void | |
631 | __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, | |
632 | struct vm_area_struct *prev, struct rb_node **rb_link, | |
633 | struct rb_node *rb_parent) | |
634 | { | |
635 | __vma_link_list(mm, vma, prev, rb_parent); | |
636 | __vma_link_rb(mm, vma, rb_link, rb_parent); | |
637 | } | |
638 | ||
639 | static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, | |
640 | struct vm_area_struct *prev, struct rb_node **rb_link, | |
641 | struct rb_node *rb_parent) | |
642 | { | |
643 | struct address_space *mapping = NULL; | |
644 | ||
645 | if (vma->vm_file) { | |
646 | mapping = vma->vm_file->f_mapping; | |
647 | i_mmap_lock_write(mapping); | |
648 | } | |
649 | ||
650 | __vma_link(mm, vma, prev, rb_link, rb_parent); | |
651 | __vma_link_file(vma); | |
652 | ||
653 | if (mapping) | |
654 | i_mmap_unlock_write(mapping); | |
655 | ||
656 | mm->map_count++; | |
657 | validate_mm(mm); | |
658 | } | |
659 | ||
660 | /* | |
661 | * Helper for vma_adjust() in the split_vma insert case: insert a vma into the | |
662 | * mm's list and rbtree. It has already been inserted into the interval tree. | |
663 | */ | |
664 | static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) | |
665 | { | |
666 | struct vm_area_struct *prev; | |
667 | struct rb_node **rb_link, *rb_parent; | |
668 | ||
669 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, | |
670 | &prev, &rb_link, &rb_parent)) | |
671 | BUG(); | |
672 | __vma_link(mm, vma, prev, rb_link, rb_parent); | |
673 | mm->map_count++; | |
674 | } | |
675 | ||
676 | static __always_inline void __vma_unlink_common(struct mm_struct *mm, | |
677 | struct vm_area_struct *vma, | |
678 | struct vm_area_struct *prev, | |
679 | bool has_prev, | |
680 | struct vm_area_struct *ignore) | |
681 | { | |
682 | struct vm_area_struct *next; | |
683 | ||
684 | vma_rb_erase_ignore(vma, &mm->mm_rb, ignore); | |
685 | next = vma->vm_next; | |
686 | if (has_prev) | |
687 | prev->vm_next = next; | |
688 | else { | |
689 | prev = vma->vm_prev; | |
690 | if (prev) | |
691 | prev->vm_next = next; | |
692 | else | |
693 | mm->mmap = next; | |
694 | } | |
695 | if (next) | |
696 | next->vm_prev = prev; | |
697 | ||
698 | /* Kill the cache */ | |
699 | vmacache_invalidate(mm); | |
700 | } | |
701 | ||
702 | static inline void __vma_unlink_prev(struct mm_struct *mm, | |
703 | struct vm_area_struct *vma, | |
704 | struct vm_area_struct *prev) | |
705 | { | |
706 | __vma_unlink_common(mm, vma, prev, true, vma); | |
707 | } | |
708 | ||
709 | /* | |
710 | * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that | |
711 | * is already present in an i_mmap tree without adjusting the tree. | |
712 | * The following helper function should be used when such adjustments | |
713 | * are necessary. The "insert" vma (if any) is to be inserted | |
714 | * before we drop the necessary locks. | |
715 | */ | |
716 | int __vma_adjust(struct vm_area_struct *vma, unsigned long start, | |
717 | unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert, | |
718 | struct vm_area_struct *expand) | |
719 | { | |
720 | struct mm_struct *mm = vma->vm_mm; | |
721 | struct vm_area_struct *next = vma->vm_next, *orig_vma = vma; | |
722 | struct address_space *mapping = NULL; | |
723 | struct rb_root_cached *root = NULL; | |
724 | struct anon_vma *anon_vma = NULL; | |
725 | struct file *file = vma->vm_file; | |
726 | bool start_changed = false, end_changed = false; | |
727 | long adjust_next = 0; | |
728 | int remove_next = 0; | |
729 | ||
730 | if (next && !insert) { | |
731 | struct vm_area_struct *exporter = NULL, *importer = NULL; | |
732 | ||
733 | if (end >= next->vm_end) { | |
734 | /* | |
735 | * vma expands, overlapping all the next, and | |
736 | * perhaps the one after too (mprotect case 6). | |
737 | * The only other cases that gets here are | |
738 | * case 1, case 7 and case 8. | |
739 | */ | |
740 | if (next == expand) { | |
741 | /* | |
742 | * The only case where we don't expand "vma" | |
743 | * and we expand "next" instead is case 8. | |
744 | */ | |
745 | VM_WARN_ON(end != next->vm_end); | |
746 | /* | |
747 | * remove_next == 3 means we're | |
748 | * removing "vma" and that to do so we | |
749 | * swapped "vma" and "next". | |
750 | */ | |
751 | remove_next = 3; | |
752 | VM_WARN_ON(file != next->vm_file); | |
753 | swap(vma, next); | |
754 | } else { | |
755 | VM_WARN_ON(expand != vma); | |
756 | /* | |
757 | * case 1, 6, 7, remove_next == 2 is case 6, | |
758 | * remove_next == 1 is case 1 or 7. | |
759 | */ | |
760 | remove_next = 1 + (end > next->vm_end); | |
761 | VM_WARN_ON(remove_next == 2 && | |
762 | end != next->vm_next->vm_end); | |
763 | VM_WARN_ON(remove_next == 1 && | |
764 | end != next->vm_end); | |
765 | /* trim end to next, for case 6 first pass */ | |
766 | end = next->vm_end; | |
767 | } | |
768 | ||
769 | exporter = next; | |
770 | importer = vma; | |
771 | ||
772 | /* | |
773 | * If next doesn't have anon_vma, import from vma after | |
774 | * next, if the vma overlaps with it. | |
775 | */ | |
776 | if (remove_next == 2 && !next->anon_vma) | |
777 | exporter = next->vm_next; | |
778 | ||
779 | } else if (end > next->vm_start) { | |
780 | /* | |
781 | * vma expands, overlapping part of the next: | |
782 | * mprotect case 5 shifting the boundary up. | |
783 | */ | |
784 | adjust_next = (end - next->vm_start) >> PAGE_SHIFT; | |
785 | exporter = next; | |
786 | importer = vma; | |
787 | VM_WARN_ON(expand != importer); | |
788 | } else if (end < vma->vm_end) { | |
789 | /* | |
790 | * vma shrinks, and !insert tells it's not | |
791 | * split_vma inserting another: so it must be | |
792 | * mprotect case 4 shifting the boundary down. | |
793 | */ | |
794 | adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); | |
795 | exporter = vma; | |
796 | importer = next; | |
797 | VM_WARN_ON(expand != importer); | |
798 | } | |
799 | ||
800 | /* | |
801 | * Easily overlooked: when mprotect shifts the boundary, | |
802 | * make sure the expanding vma has anon_vma set if the | |
803 | * shrinking vma had, to cover any anon pages imported. | |
804 | */ | |
805 | if (exporter && exporter->anon_vma && !importer->anon_vma) { | |
806 | int error; | |
807 | ||
808 | importer->anon_vma = exporter->anon_vma; | |
809 | error = anon_vma_clone(importer, exporter); | |
810 | if (error) | |
811 | return error; | |
812 | } | |
813 | } | |
814 | again: | |
815 | vma_adjust_trans_huge(orig_vma, start, end, adjust_next); | |
816 | ||
817 | if (file) { | |
818 | mapping = file->f_mapping; | |
819 | root = &mapping->i_mmap; | |
820 | uprobe_munmap(vma, vma->vm_start, vma->vm_end); | |
821 | ||
822 | if (adjust_next) | |
823 | uprobe_munmap(next, next->vm_start, next->vm_end); | |
824 | ||
825 | i_mmap_lock_write(mapping); | |
826 | if (insert) { | |
827 | /* | |
828 | * Put into interval tree now, so instantiated pages | |
829 | * are visible to arm/parisc __flush_dcache_page | |
830 | * throughout; but we cannot insert into address | |
831 | * space until vma start or end is updated. | |
832 | */ | |
833 | __vma_link_file(insert); | |
834 | } | |
835 | } | |
836 | ||
837 | anon_vma = vma->anon_vma; | |
838 | if (!anon_vma && adjust_next) | |
839 | anon_vma = next->anon_vma; | |
840 | if (anon_vma) { | |
841 | VM_WARN_ON(adjust_next && next->anon_vma && | |
842 | anon_vma != next->anon_vma); | |
843 | anon_vma_lock_write(anon_vma); | |
844 | anon_vma_interval_tree_pre_update_vma(vma); | |
845 | if (adjust_next) | |
846 | anon_vma_interval_tree_pre_update_vma(next); | |
847 | } | |
848 | ||
849 | if (root) { | |
850 | flush_dcache_mmap_lock(mapping); | |
851 | vma_interval_tree_remove(vma, root); | |
852 | if (adjust_next) | |
853 | vma_interval_tree_remove(next, root); | |
854 | } | |
855 | ||
856 | if (start != vma->vm_start) { | |
857 | vma->vm_start = start; | |
858 | start_changed = true; | |
859 | } | |
860 | if (end != vma->vm_end) { | |
861 | vma->vm_end = end; | |
862 | end_changed = true; | |
863 | } | |
864 | vma->vm_pgoff = pgoff; | |
865 | if (adjust_next) { | |
866 | next->vm_start += adjust_next << PAGE_SHIFT; | |
867 | next->vm_pgoff += adjust_next; | |
868 | } | |
869 | ||
870 | if (root) { | |
871 | if (adjust_next) | |
872 | vma_interval_tree_insert(next, root); | |
873 | vma_interval_tree_insert(vma, root); | |
874 | flush_dcache_mmap_unlock(mapping); | |
875 | } | |
876 | ||
877 | if (remove_next) { | |
878 | /* | |
879 | * vma_merge has merged next into vma, and needs | |
880 | * us to remove next before dropping the locks. | |
881 | */ | |
882 | if (remove_next != 3) | |
883 | __vma_unlink_prev(mm, next, vma); | |
884 | else | |
885 | /* | |
886 | * vma is not before next if they've been | |
887 | * swapped. | |
888 | * | |
889 | * pre-swap() next->vm_start was reduced so | |
890 | * tell validate_mm_rb to ignore pre-swap() | |
891 | * "next" (which is stored in post-swap() | |
892 | * "vma"). | |
893 | */ | |
894 | __vma_unlink_common(mm, next, NULL, false, vma); | |
895 | if (file) | |
896 | __remove_shared_vm_struct(next, file, mapping); | |
897 | } else if (insert) { | |
898 | /* | |
899 | * split_vma has split insert from vma, and needs | |
900 | * us to insert it before dropping the locks | |
901 | * (it may either follow vma or precede it). | |
902 | */ | |
903 | __insert_vm_struct(mm, insert); | |
904 | } else { | |
905 | if (start_changed) | |
906 | vma_gap_update(vma); | |
907 | if (end_changed) { | |
908 | if (!next) | |
909 | mm->highest_vm_end = vm_end_gap(vma); | |
910 | else if (!adjust_next) | |
911 | vma_gap_update(next); | |
912 | } | |
913 | } | |
914 | ||
915 | if (anon_vma) { | |
916 | anon_vma_interval_tree_post_update_vma(vma); | |
917 | if (adjust_next) | |
918 | anon_vma_interval_tree_post_update_vma(next); | |
919 | anon_vma_unlock_write(anon_vma); | |
920 | } | |
921 | if (mapping) | |
922 | i_mmap_unlock_write(mapping); | |
923 | ||
924 | if (root) { | |
925 | uprobe_mmap(vma); | |
926 | ||
927 | if (adjust_next) | |
928 | uprobe_mmap(next); | |
929 | } | |
930 | ||
931 | if (remove_next) { | |
932 | if (file) { | |
933 | uprobe_munmap(next, next->vm_start, next->vm_end); | |
934 | fput(file); | |
935 | } | |
936 | if (next->anon_vma) | |
937 | anon_vma_merge(vma, next); | |
938 | mm->map_count--; | |
939 | mpol_put(vma_policy(next)); | |
940 | vm_area_free(next); | |
941 | /* | |
942 | * In mprotect's case 6 (see comments on vma_merge), | |
943 | * we must remove another next too. It would clutter | |
944 | * up the code too much to do both in one go. | |
945 | */ | |
946 | if (remove_next != 3) { | |
947 | /* | |
948 | * If "next" was removed and vma->vm_end was | |
949 | * expanded (up) over it, in turn | |
950 | * "next->vm_prev->vm_end" changed and the | |
951 | * "vma->vm_next" gap must be updated. | |
952 | */ | |
953 | next = vma->vm_next; | |
954 | } else { | |
955 | /* | |
956 | * For the scope of the comment "next" and | |
957 | * "vma" considered pre-swap(): if "vma" was | |
958 | * removed, next->vm_start was expanded (down) | |
959 | * over it and the "next" gap must be updated. | |
960 | * Because of the swap() the post-swap() "vma" | |
961 | * actually points to pre-swap() "next" | |
962 | * (post-swap() "next" as opposed is now a | |
963 | * dangling pointer). | |
964 | */ | |
965 | next = vma; | |
966 | } | |
967 | if (remove_next == 2) { | |
968 | remove_next = 1; | |
969 | end = next->vm_end; | |
970 | goto again; | |
971 | } | |
972 | else if (next) | |
973 | vma_gap_update(next); | |
974 | else { | |
975 | /* | |
976 | * If remove_next == 2 we obviously can't | |
977 | * reach this path. | |
978 | * | |
979 | * If remove_next == 3 we can't reach this | |
980 | * path because pre-swap() next is always not | |
981 | * NULL. pre-swap() "next" is not being | |
982 | * removed and its next->vm_end is not altered | |
983 | * (and furthermore "end" already matches | |
984 | * next->vm_end in remove_next == 3). | |
985 | * | |
986 | * We reach this only in the remove_next == 1 | |
987 | * case if the "next" vma that was removed was | |
988 | * the highest vma of the mm. However in such | |
989 | * case next->vm_end == "end" and the extended | |
990 | * "vma" has vma->vm_end == next->vm_end so | |
991 | * mm->highest_vm_end doesn't need any update | |
992 | * in remove_next == 1 case. | |
993 | */ | |
994 | VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma)); | |
995 | } | |
996 | } | |
997 | if (insert && file) | |
998 | uprobe_mmap(insert); | |
999 | ||
1000 | validate_mm(mm); | |
1001 | ||
1002 | return 0; | |
1003 | } | |
1004 | ||
1005 | /* | |
1006 | * If the vma has a ->close operation then the driver probably needs to release | |
1007 | * per-vma resources, so we don't attempt to merge those. | |
1008 | */ | |
1009 | static inline int is_mergeable_vma(struct vm_area_struct *vma, | |
1010 | struct file *file, unsigned long vm_flags, | |
1011 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
1012 | { | |
1013 | /* | |
1014 | * VM_SOFTDIRTY should not prevent from VMA merging, if we | |
1015 | * match the flags but dirty bit -- the caller should mark | |
1016 | * merged VMA as dirty. If dirty bit won't be excluded from | |
1017 | * comparison, we increase pressure on the memory system forcing | |
1018 | * the kernel to generate new VMAs when old one could be | |
1019 | * extended instead. | |
1020 | */ | |
1021 | if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) | |
1022 | return 0; | |
1023 | if (vma->vm_file != file) | |
1024 | return 0; | |
1025 | if (vma->vm_ops && vma->vm_ops->close) | |
1026 | return 0; | |
1027 | if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) | |
1028 | return 0; | |
1029 | return 1; | |
1030 | } | |
1031 | ||
1032 | static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, | |
1033 | struct anon_vma *anon_vma2, | |
1034 | struct vm_area_struct *vma) | |
1035 | { | |
1036 | /* | |
1037 | * The list_is_singular() test is to avoid merging VMA cloned from | |
1038 | * parents. This can improve scalability caused by anon_vma lock. | |
1039 | */ | |
1040 | if ((!anon_vma1 || !anon_vma2) && (!vma || | |
1041 | list_is_singular(&vma->anon_vma_chain))) | |
1042 | return 1; | |
1043 | return anon_vma1 == anon_vma2; | |
1044 | } | |
1045 | ||
1046 | /* | |
1047 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) | |
1048 | * in front of (at a lower virtual address and file offset than) the vma. | |
1049 | * | |
1050 | * We cannot merge two vmas if they have differently assigned (non-NULL) | |
1051 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. | |
1052 | * | |
1053 | * We don't check here for the merged mmap wrapping around the end of pagecache | |
1054 | * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which | |
1055 | * wrap, nor mmaps which cover the final page at index -1UL. | |
1056 | */ | |
1057 | static int | |
1058 | can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, | |
1059 | struct anon_vma *anon_vma, struct file *file, | |
1060 | pgoff_t vm_pgoff, | |
1061 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
1062 | { | |
1063 | if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && | |
1064 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { | |
1065 | if (vma->vm_pgoff == vm_pgoff) | |
1066 | return 1; | |
1067 | } | |
1068 | return 0; | |
1069 | } | |
1070 | ||
1071 | /* | |
1072 | * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) | |
1073 | * beyond (at a higher virtual address and file offset than) the vma. | |
1074 | * | |
1075 | * We cannot merge two vmas if they have differently assigned (non-NULL) | |
1076 | * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. | |
1077 | */ | |
1078 | static int | |
1079 | can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, | |
1080 | struct anon_vma *anon_vma, struct file *file, | |
1081 | pgoff_t vm_pgoff, | |
1082 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
1083 | { | |
1084 | if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && | |
1085 | is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { | |
1086 | pgoff_t vm_pglen; | |
1087 | vm_pglen = vma_pages(vma); | |
1088 | if (vma->vm_pgoff + vm_pglen == vm_pgoff) | |
1089 | return 1; | |
1090 | } | |
1091 | return 0; | |
1092 | } | |
1093 | ||
1094 | /* | |
1095 | * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out | |
1096 | * whether that can be merged with its predecessor or its successor. | |
1097 | * Or both (it neatly fills a hole). | |
1098 | * | |
1099 | * In most cases - when called for mmap, brk or mremap - [addr,end) is | |
1100 | * certain not to be mapped by the time vma_merge is called; but when | |
1101 | * called for mprotect, it is certain to be already mapped (either at | |
1102 | * an offset within prev, or at the start of next), and the flags of | |
1103 | * this area are about to be changed to vm_flags - and the no-change | |
1104 | * case has already been eliminated. | |
1105 | * | |
1106 | * The following mprotect cases have to be considered, where AAAA is | |
1107 | * the area passed down from mprotect_fixup, never extending beyond one | |
1108 | * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: | |
1109 | * | |
1110 | * AAAA AAAA AAAA AAAA | |
1111 | * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX | |
1112 | * cannot merge might become might become might become | |
1113 | * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or | |
1114 | * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or | |
1115 | * mremap move: PPPPXXXXXXXX 8 | |
1116 | * AAAA | |
1117 | * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN | |
1118 | * might become case 1 below case 2 below case 3 below | |
1119 | * | |
1120 | * It is important for case 8 that the vma NNNN overlapping the | |
1121 | * region AAAA is never going to extended over XXXX. Instead XXXX must | |
1122 | * be extended in region AAAA and NNNN must be removed. This way in | |
1123 | * all cases where vma_merge succeeds, the moment vma_adjust drops the | |
1124 | * rmap_locks, the properties of the merged vma will be already | |
1125 | * correct for the whole merged range. Some of those properties like | |
1126 | * vm_page_prot/vm_flags may be accessed by rmap_walks and they must | |
1127 | * be correct for the whole merged range immediately after the | |
1128 | * rmap_locks are released. Otherwise if XXXX would be removed and | |
1129 | * NNNN would be extended over the XXXX range, remove_migration_ptes | |
1130 | * or other rmap walkers (if working on addresses beyond the "end" | |
1131 | * parameter) may establish ptes with the wrong permissions of NNNN | |
1132 | * instead of the right permissions of XXXX. | |
1133 | */ | |
1134 | struct vm_area_struct *vma_merge(struct mm_struct *mm, | |
1135 | struct vm_area_struct *prev, unsigned long addr, | |
1136 | unsigned long end, unsigned long vm_flags, | |
1137 | struct anon_vma *anon_vma, struct file *file, | |
1138 | pgoff_t pgoff, struct mempolicy *policy, | |
1139 | struct vm_userfaultfd_ctx vm_userfaultfd_ctx) | |
1140 | { | |
1141 | pgoff_t pglen = (end - addr) >> PAGE_SHIFT; | |
1142 | struct vm_area_struct *area, *next; | |
1143 | int err; | |
1144 | ||
1145 | /* | |
1146 | * We later require that vma->vm_flags == vm_flags, | |
1147 | * so this tests vma->vm_flags & VM_SPECIAL, too. | |
1148 | */ | |
1149 | if (vm_flags & VM_SPECIAL) | |
1150 | return NULL; | |
1151 | ||
1152 | if (prev) | |
1153 | next = prev->vm_next; | |
1154 | else | |
1155 | next = mm->mmap; | |
1156 | area = next; | |
1157 | if (area && area->vm_end == end) /* cases 6, 7, 8 */ | |
1158 | next = next->vm_next; | |
1159 | ||
1160 | /* verify some invariant that must be enforced by the caller */ | |
1161 | VM_WARN_ON(prev && addr <= prev->vm_start); | |
1162 | VM_WARN_ON(area && end > area->vm_end); | |
1163 | VM_WARN_ON(addr >= end); | |
1164 | ||
1165 | /* | |
1166 | * Can it merge with the predecessor? | |
1167 | */ | |
1168 | if (prev && prev->vm_end == addr && | |
1169 | mpol_equal(vma_policy(prev), policy) && | |
1170 | can_vma_merge_after(prev, vm_flags, | |
1171 | anon_vma, file, pgoff, | |
1172 | vm_userfaultfd_ctx)) { | |
1173 | /* | |
1174 | * OK, it can. Can we now merge in the successor as well? | |
1175 | */ | |
1176 | if (next && end == next->vm_start && | |
1177 | mpol_equal(policy, vma_policy(next)) && | |
1178 | can_vma_merge_before(next, vm_flags, | |
1179 | anon_vma, file, | |
1180 | pgoff+pglen, | |
1181 | vm_userfaultfd_ctx) && | |
1182 | is_mergeable_anon_vma(prev->anon_vma, | |
1183 | next->anon_vma, NULL)) { | |
1184 | /* cases 1, 6 */ | |
1185 | err = __vma_adjust(prev, prev->vm_start, | |
1186 | next->vm_end, prev->vm_pgoff, NULL, | |
1187 | prev); | |
1188 | } else /* cases 2, 5, 7 */ | |
1189 | err = __vma_adjust(prev, prev->vm_start, | |
1190 | end, prev->vm_pgoff, NULL, prev); | |
1191 | if (err) | |
1192 | return NULL; | |
1193 | khugepaged_enter_vma_merge(prev, vm_flags); | |
1194 | return prev; | |
1195 | } | |
1196 | ||
1197 | /* | |
1198 | * Can this new request be merged in front of next? | |
1199 | */ | |
1200 | if (next && end == next->vm_start && | |
1201 | mpol_equal(policy, vma_policy(next)) && | |
1202 | can_vma_merge_before(next, vm_flags, | |
1203 | anon_vma, file, pgoff+pglen, | |
1204 | vm_userfaultfd_ctx)) { | |
1205 | if (prev && addr < prev->vm_end) /* case 4 */ | |
1206 | err = __vma_adjust(prev, prev->vm_start, | |
1207 | addr, prev->vm_pgoff, NULL, next); | |
1208 | else { /* cases 3, 8 */ | |
1209 | err = __vma_adjust(area, addr, next->vm_end, | |
1210 | next->vm_pgoff - pglen, NULL, next); | |
1211 | /* | |
1212 | * In case 3 area is already equal to next and | |
1213 | * this is a noop, but in case 8 "area" has | |
1214 | * been removed and next was expanded over it. | |
1215 | */ | |
1216 | area = next; | |
1217 | } | |
1218 | if (err) | |
1219 | return NULL; | |
1220 | khugepaged_enter_vma_merge(area, vm_flags); | |
1221 | return area; | |
1222 | } | |
1223 | ||
1224 | return NULL; | |
1225 | } | |
1226 | ||
1227 | /* | |
1228 | * Rough compatbility check to quickly see if it's even worth looking | |
1229 | * at sharing an anon_vma. | |
1230 | * | |
1231 | * They need to have the same vm_file, and the flags can only differ | |
1232 | * in things that mprotect may change. | |
1233 | * | |
1234 | * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that | |
1235 | * we can merge the two vma's. For example, we refuse to merge a vma if | |
1236 | * there is a vm_ops->close() function, because that indicates that the | |
1237 | * driver is doing some kind of reference counting. But that doesn't | |
1238 | * really matter for the anon_vma sharing case. | |
1239 | */ | |
1240 | static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) | |
1241 | { | |
1242 | return a->vm_end == b->vm_start && | |
1243 | mpol_equal(vma_policy(a), vma_policy(b)) && | |
1244 | a->vm_file == b->vm_file && | |
1245 | !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) && | |
1246 | b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); | |
1247 | } | |
1248 | ||
1249 | /* | |
1250 | * Do some basic sanity checking to see if we can re-use the anon_vma | |
1251 | * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be | |
1252 | * the same as 'old', the other will be the new one that is trying | |
1253 | * to share the anon_vma. | |
1254 | * | |
1255 | * NOTE! This runs with mm_sem held for reading, so it is possible that | |
1256 | * the anon_vma of 'old' is concurrently in the process of being set up | |
1257 | * by another page fault trying to merge _that_. But that's ok: if it | |
1258 | * is being set up, that automatically means that it will be a singleton | |
1259 | * acceptable for merging, so we can do all of this optimistically. But | |
1260 | * we do that READ_ONCE() to make sure that we never re-load the pointer. | |
1261 | * | |
1262 | * IOW: that the "list_is_singular()" test on the anon_vma_chain only | |
1263 | * matters for the 'stable anon_vma' case (ie the thing we want to avoid | |
1264 | * is to return an anon_vma that is "complex" due to having gone through | |
1265 | * a fork). | |
1266 | * | |
1267 | * We also make sure that the two vma's are compatible (adjacent, | |
1268 | * and with the same memory policies). That's all stable, even with just | |
1269 | * a read lock on the mm_sem. | |
1270 | */ | |
1271 | static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) | |
1272 | { | |
1273 | if (anon_vma_compatible(a, b)) { | |
1274 | struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); | |
1275 | ||
1276 | if (anon_vma && list_is_singular(&old->anon_vma_chain)) | |
1277 | return anon_vma; | |
1278 | } | |
1279 | return NULL; | |
1280 | } | |
1281 | ||
1282 | /* | |
1283 | * find_mergeable_anon_vma is used by anon_vma_prepare, to check | |
1284 | * neighbouring vmas for a suitable anon_vma, before it goes off | |
1285 | * to allocate a new anon_vma. It checks because a repetitive | |
1286 | * sequence of mprotects and faults may otherwise lead to distinct | |
1287 | * anon_vmas being allocated, preventing vma merge in subsequent | |
1288 | * mprotect. | |
1289 | */ | |
1290 | struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) | |
1291 | { | |
1292 | struct anon_vma *anon_vma; | |
1293 | struct vm_area_struct *near; | |
1294 | ||
1295 | near = vma->vm_next; | |
1296 | if (!near) | |
1297 | goto try_prev; | |
1298 | ||
1299 | anon_vma = reusable_anon_vma(near, vma, near); | |
1300 | if (anon_vma) | |
1301 | return anon_vma; | |
1302 | try_prev: | |
1303 | near = vma->vm_prev; | |
1304 | if (!near) | |
1305 | goto none; | |
1306 | ||
1307 | anon_vma = reusable_anon_vma(near, near, vma); | |
1308 | if (anon_vma) | |
1309 | return anon_vma; | |
1310 | none: | |
1311 | /* | |
1312 | * There's no absolute need to look only at touching neighbours: | |
1313 | * we could search further afield for "compatible" anon_vmas. | |
1314 | * But it would probably just be a waste of time searching, | |
1315 | * or lead to too many vmas hanging off the same anon_vma. | |
1316 | * We're trying to allow mprotect remerging later on, | |
1317 | * not trying to minimize memory used for anon_vmas. | |
1318 | */ | |
1319 | return NULL; | |
1320 | } | |
1321 | ||
1322 | /* | |
1323 | * If a hint addr is less than mmap_min_addr change hint to be as | |
1324 | * low as possible but still greater than mmap_min_addr | |
1325 | */ | |
1326 | static inline unsigned long round_hint_to_min(unsigned long hint) | |
1327 | { | |
1328 | hint &= PAGE_MASK; | |
1329 | if (((void *)hint != NULL) && | |
1330 | (hint < mmap_min_addr)) | |
1331 | return PAGE_ALIGN(mmap_min_addr); | |
1332 | return hint; | |
1333 | } | |
1334 | ||
1335 | static inline int mlock_future_check(struct mm_struct *mm, | |
1336 | unsigned long flags, | |
1337 | unsigned long len) | |
1338 | { | |
1339 | unsigned long locked, lock_limit; | |
1340 | ||
1341 | /* mlock MCL_FUTURE? */ | |
1342 | if (flags & VM_LOCKED) { | |
1343 | locked = len >> PAGE_SHIFT; | |
1344 | locked += mm->locked_vm; | |
1345 | lock_limit = rlimit(RLIMIT_MEMLOCK); | |
1346 | lock_limit >>= PAGE_SHIFT; | |
1347 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) | |
1348 | return -EAGAIN; | |
1349 | } | |
1350 | return 0; | |
1351 | } | |
1352 | ||
1353 | static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) | |
1354 | { | |
1355 | if (S_ISREG(inode->i_mode)) | |
1356 | return MAX_LFS_FILESIZE; | |
1357 | ||
1358 | if (S_ISBLK(inode->i_mode)) | |
1359 | return MAX_LFS_FILESIZE; | |
1360 | ||
1361 | /* Special "we do even unsigned file positions" case */ | |
1362 | if (file->f_mode & FMODE_UNSIGNED_OFFSET) | |
1363 | return 0; | |
1364 | ||
1365 | /* Yes, random drivers might want more. But I'm tired of buggy drivers */ | |
1366 | return ULONG_MAX; | |
1367 | } | |
1368 | ||
1369 | static inline bool file_mmap_ok(struct file *file, struct inode *inode, | |
1370 | unsigned long pgoff, unsigned long len) | |
1371 | { | |
1372 | u64 maxsize = file_mmap_size_max(file, inode); | |
1373 | ||
1374 | if (maxsize && len > maxsize) | |
1375 | return false; | |
1376 | maxsize -= len; | |
1377 | if (pgoff > maxsize >> PAGE_SHIFT) | |
1378 | return false; | |
1379 | return true; | |
1380 | } | |
1381 | ||
1382 | /* | |
1383 | * The caller must hold down_write(¤t->mm->mmap_sem). | |
1384 | */ | |
1385 | unsigned long do_mmap(struct file *file, unsigned long addr, | |
1386 | unsigned long len, unsigned long prot, | |
1387 | unsigned long flags, vm_flags_t vm_flags, | |
1388 | unsigned long pgoff, unsigned long *populate, | |
1389 | struct list_head *uf) | |
1390 | { | |
1391 | struct mm_struct *mm = current->mm; | |
1392 | int pkey = 0; | |
1393 | ||
1394 | *populate = 0; | |
1395 | ||
1396 | if (!len) | |
1397 | return -EINVAL; | |
1398 | ||
1399 | /* | |
1400 | * Does the application expect PROT_READ to imply PROT_EXEC? | |
1401 | * | |
1402 | * (the exception is when the underlying filesystem is noexec | |
1403 | * mounted, in which case we dont add PROT_EXEC.) | |
1404 | */ | |
1405 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) | |
1406 | if (!(file && path_noexec(&file->f_path))) | |
1407 | prot |= PROT_EXEC; | |
1408 | ||
1409 | /* force arch specific MAP_FIXED handling in get_unmapped_area */ | |
1410 | if (flags & MAP_FIXED_NOREPLACE) | |
1411 | flags |= MAP_FIXED; | |
1412 | ||
1413 | if (!(flags & MAP_FIXED)) | |
1414 | addr = round_hint_to_min(addr); | |
1415 | ||
1416 | /* Careful about overflows.. */ | |
1417 | len = PAGE_ALIGN(len); | |
1418 | if (!len) | |
1419 | return -ENOMEM; | |
1420 | ||
1421 | /* offset overflow? */ | |
1422 | if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) | |
1423 | return -EOVERFLOW; | |
1424 | ||
1425 | /* Too many mappings? */ | |
1426 | if (mm->map_count > sysctl_max_map_count) | |
1427 | return -ENOMEM; | |
1428 | ||
1429 | /* Obtain the address to map to. we verify (or select) it and ensure | |
1430 | * that it represents a valid section of the address space. | |
1431 | */ | |
1432 | addr = get_unmapped_area(file, addr, len, pgoff, flags); | |
1433 | if (offset_in_page(addr)) | |
1434 | return addr; | |
1435 | ||
1436 | if (flags & MAP_FIXED_NOREPLACE) { | |
1437 | struct vm_area_struct *vma = find_vma(mm, addr); | |
1438 | ||
1439 | if (vma && vma->vm_start < addr + len) | |
1440 | return -EEXIST; | |
1441 | } | |
1442 | ||
1443 | if (prot == PROT_EXEC) { | |
1444 | pkey = execute_only_pkey(mm); | |
1445 | if (pkey < 0) | |
1446 | pkey = 0; | |
1447 | } | |
1448 | ||
1449 | /* Do simple checking here so the lower-level routines won't have | |
1450 | * to. we assume access permissions have been handled by the open | |
1451 | * of the memory object, so we don't do any here. | |
1452 | */ | |
1453 | vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) | | |
1454 | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; | |
1455 | ||
1456 | if (flags & MAP_LOCKED) | |
1457 | if (!can_do_mlock()) | |
1458 | return -EPERM; | |
1459 | ||
1460 | if (mlock_future_check(mm, vm_flags, len)) | |
1461 | return -EAGAIN; | |
1462 | ||
1463 | if (file) { | |
1464 | struct inode *inode = file_inode(file); | |
1465 | unsigned long flags_mask; | |
1466 | ||
1467 | if (!file_mmap_ok(file, inode, pgoff, len)) | |
1468 | return -EOVERFLOW; | |
1469 | ||
1470 | flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; | |
1471 | ||
1472 | switch (flags & MAP_TYPE) { | |
1473 | case MAP_SHARED: | |
1474 | /* | |
1475 | * Force use of MAP_SHARED_VALIDATE with non-legacy | |
1476 | * flags. E.g. MAP_SYNC is dangerous to use with | |
1477 | * MAP_SHARED as you don't know which consistency model | |
1478 | * you will get. We silently ignore unsupported flags | |
1479 | * with MAP_SHARED to preserve backward compatibility. | |
1480 | */ | |
1481 | flags &= LEGACY_MAP_MASK; | |
1482 | /* fall through */ | |
1483 | case MAP_SHARED_VALIDATE: | |
1484 | if (flags & ~flags_mask) | |
1485 | return -EOPNOTSUPP; | |
1486 | if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) | |
1487 | return -EACCES; | |
1488 | ||
1489 | /* | |
1490 | * Make sure we don't allow writing to an append-only | |
1491 | * file.. | |
1492 | */ | |
1493 | if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) | |
1494 | return -EACCES; | |
1495 | ||
1496 | /* | |
1497 | * Make sure there are no mandatory locks on the file. | |
1498 | */ | |
1499 | if (locks_verify_locked(file)) | |
1500 | return -EAGAIN; | |
1501 | ||
1502 | vm_flags |= VM_SHARED | VM_MAYSHARE; | |
1503 | if (!(file->f_mode & FMODE_WRITE)) | |
1504 | vm_flags &= ~(VM_MAYWRITE | VM_SHARED); | |
1505 | ||
1506 | /* fall through */ | |
1507 | case MAP_PRIVATE: | |
1508 | if (!(file->f_mode & FMODE_READ)) | |
1509 | return -EACCES; | |
1510 | if (path_noexec(&file->f_path)) { | |
1511 | if (vm_flags & VM_EXEC) | |
1512 | return -EPERM; | |
1513 | vm_flags &= ~VM_MAYEXEC; | |
1514 | } | |
1515 | ||
1516 | if (!file->f_op->mmap) | |
1517 | return -ENODEV; | |
1518 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) | |
1519 | return -EINVAL; | |
1520 | break; | |
1521 | ||
1522 | default: | |
1523 | return -EINVAL; | |
1524 | } | |
1525 | } else { | |
1526 | switch (flags & MAP_TYPE) { | |
1527 | case MAP_SHARED: | |
1528 | if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) | |
1529 | return -EINVAL; | |
1530 | /* | |
1531 | * Ignore pgoff. | |
1532 | */ | |
1533 | pgoff = 0; | |
1534 | vm_flags |= VM_SHARED | VM_MAYSHARE; | |
1535 | break; | |
1536 | case MAP_PRIVATE: | |
1537 | /* | |
1538 | * Set pgoff according to addr for anon_vma. | |
1539 | */ | |
1540 | pgoff = addr >> PAGE_SHIFT; | |
1541 | break; | |
1542 | default: | |
1543 | return -EINVAL; | |
1544 | } | |
1545 | } | |
1546 | ||
1547 | /* | |
1548 | * Set 'VM_NORESERVE' if we should not account for the | |
1549 | * memory use of this mapping. | |
1550 | */ | |
1551 | if (flags & MAP_NORESERVE) { | |
1552 | /* We honor MAP_NORESERVE if allowed to overcommit */ | |
1553 | if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) | |
1554 | vm_flags |= VM_NORESERVE; | |
1555 | ||
1556 | /* hugetlb applies strict overcommit unless MAP_NORESERVE */ | |
1557 | if (file && is_file_hugepages(file)) | |
1558 | vm_flags |= VM_NORESERVE; | |
1559 | } | |
1560 | ||
1561 | addr = mmap_region(file, addr, len, vm_flags, pgoff, uf); | |
1562 | if (!IS_ERR_VALUE(addr) && | |
1563 | ((vm_flags & VM_LOCKED) || | |
1564 | (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) | |
1565 | *populate = len; | |
1566 | return addr; | |
1567 | } | |
1568 | ||
1569 | unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, | |
1570 | unsigned long prot, unsigned long flags, | |
1571 | unsigned long fd, unsigned long pgoff) | |
1572 | { | |
1573 | struct file *file = NULL; | |
1574 | unsigned long retval; | |
1575 | ||
1576 | if (!(flags & MAP_ANONYMOUS)) { | |
1577 | audit_mmap_fd(fd, flags); | |
1578 | file = fget(fd); | |
1579 | if (!file) | |
1580 | return -EBADF; | |
1581 | if (is_file_hugepages(file)) | |
1582 | len = ALIGN(len, huge_page_size(hstate_file(file))); | |
1583 | retval = -EINVAL; | |
1584 | if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) | |
1585 | goto out_fput; | |
1586 | } else if (flags & MAP_HUGETLB) { | |
1587 | struct user_struct *user = NULL; | |
1588 | struct hstate *hs; | |
1589 | ||
1590 | hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); | |
1591 | if (!hs) | |
1592 | return -EINVAL; | |
1593 | ||
1594 | len = ALIGN(len, huge_page_size(hs)); | |
1595 | /* | |
1596 | * VM_NORESERVE is used because the reservations will be | |
1597 | * taken when vm_ops->mmap() is called | |
1598 | * A dummy user value is used because we are not locking | |
1599 | * memory so no accounting is necessary | |
1600 | */ | |
1601 | file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, | |
1602 | VM_NORESERVE, | |
1603 | &user, HUGETLB_ANONHUGE_INODE, | |
1604 | (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); | |
1605 | if (IS_ERR(file)) | |
1606 | return PTR_ERR(file); | |
1607 | } | |
1608 | ||
1609 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); | |
1610 | ||
1611 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); | |
1612 | out_fput: | |
1613 | if (file) | |
1614 | fput(file); | |
1615 | return retval; | |
1616 | } | |
1617 | ||
1618 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, | |
1619 | unsigned long, prot, unsigned long, flags, | |
1620 | unsigned long, fd, unsigned long, pgoff) | |
1621 | { | |
1622 | return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); | |
1623 | } | |
1624 | ||
1625 | #ifdef __ARCH_WANT_SYS_OLD_MMAP | |
1626 | struct mmap_arg_struct { | |
1627 | unsigned long addr; | |
1628 | unsigned long len; | |
1629 | unsigned long prot; | |
1630 | unsigned long flags; | |
1631 | unsigned long fd; | |
1632 | unsigned long offset; | |
1633 | }; | |
1634 | ||
1635 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) | |
1636 | { | |
1637 | struct mmap_arg_struct a; | |
1638 | ||
1639 | if (copy_from_user(&a, arg, sizeof(a))) | |
1640 | return -EFAULT; | |
1641 | if (offset_in_page(a.offset)) | |
1642 | return -EINVAL; | |
1643 | ||
1644 | return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, | |
1645 | a.offset >> PAGE_SHIFT); | |
1646 | } | |
1647 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ | |
1648 | ||
1649 | /* | |
1650 | * Some shared mappings will want the pages marked read-only | |
1651 | * to track write events. If so, we'll downgrade vm_page_prot | |
1652 | * to the private version (using protection_map[] without the | |
1653 | * VM_SHARED bit). | |
1654 | */ | |
1655 | int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) | |
1656 | { | |
1657 | vm_flags_t vm_flags = vma->vm_flags; | |
1658 | const struct vm_operations_struct *vm_ops = vma->vm_ops; | |
1659 | ||
1660 | /* If it was private or non-writable, the write bit is already clear */ | |
1661 | if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) | |
1662 | return 0; | |
1663 | ||
1664 | /* The backer wishes to know when pages are first written to? */ | |
1665 | if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite)) | |
1666 | return 1; | |
1667 | ||
1668 | /* The open routine did something to the protections that pgprot_modify | |
1669 | * won't preserve? */ | |
1670 | if (pgprot_val(vm_page_prot) != | |
1671 | pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags))) | |
1672 | return 0; | |
1673 | ||
1674 | /* Do we need to track softdirty? */ | |
1675 | if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) | |
1676 | return 1; | |
1677 | ||
1678 | /* Specialty mapping? */ | |
1679 | if (vm_flags & VM_PFNMAP) | |
1680 | return 0; | |
1681 | ||
1682 | /* Can the mapping track the dirty pages? */ | |
1683 | return vma->vm_file && vma->vm_file->f_mapping && | |
1684 | mapping_cap_account_dirty(vma->vm_file->f_mapping); | |
1685 | } | |
1686 | ||
1687 | /* | |
1688 | * We account for memory if it's a private writeable mapping, | |
1689 | * not hugepages and VM_NORESERVE wasn't set. | |
1690 | */ | |
1691 | static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) | |
1692 | { | |
1693 | /* | |
1694 | * hugetlb has its own accounting separate from the core VM | |
1695 | * VM_HUGETLB may not be set yet so we cannot check for that flag. | |
1696 | */ | |
1697 | if (file && is_file_hugepages(file)) | |
1698 | return 0; | |
1699 | ||
1700 | return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; | |
1701 | } | |
1702 | ||
1703 | unsigned long mmap_region(struct file *file, unsigned long addr, | |
1704 | unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, | |
1705 | struct list_head *uf) | |
1706 | { | |
1707 | struct mm_struct *mm = current->mm; | |
1708 | struct vm_area_struct *vma, *prev; | |
1709 | int error; | |
1710 | struct rb_node **rb_link, *rb_parent; | |
1711 | unsigned long charged = 0; | |
1712 | ||
1713 | /* Check against address space limit. */ | |
1714 | if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { | |
1715 | unsigned long nr_pages; | |
1716 | ||
1717 | /* | |
1718 | * MAP_FIXED may remove pages of mappings that intersects with | |
1719 | * requested mapping. Account for the pages it would unmap. | |
1720 | */ | |
1721 | nr_pages = count_vma_pages_range(mm, addr, addr + len); | |
1722 | ||
1723 | if (!may_expand_vm(mm, vm_flags, | |
1724 | (len >> PAGE_SHIFT) - nr_pages)) | |
1725 | return -ENOMEM; | |
1726 | } | |
1727 | ||
1728 | /* Clear old maps */ | |
1729 | while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, | |
1730 | &rb_parent)) { | |
1731 | if (do_munmap(mm, addr, len, uf)) | |
1732 | return -ENOMEM; | |
1733 | } | |
1734 | ||
1735 | /* | |
1736 | * Private writable mapping: check memory availability | |
1737 | */ | |
1738 | if (accountable_mapping(file, vm_flags)) { | |
1739 | charged = len >> PAGE_SHIFT; | |
1740 | if (security_vm_enough_memory_mm(mm, charged)) | |
1741 | return -ENOMEM; | |
1742 | vm_flags |= VM_ACCOUNT; | |
1743 | } | |
1744 | ||
1745 | /* | |
1746 | * Can we just expand an old mapping? | |
1747 | */ | |
1748 | vma = vma_merge(mm, prev, addr, addr + len, vm_flags, | |
1749 | NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX); | |
1750 | if (vma) | |
1751 | goto out; | |
1752 | ||
1753 | /* | |
1754 | * Determine the object being mapped and call the appropriate | |
1755 | * specific mapper. the address has already been validated, but | |
1756 | * not unmapped, but the maps are removed from the list. | |
1757 | */ | |
1758 | vma = vm_area_alloc(mm); | |
1759 | if (!vma) { | |
1760 | error = -ENOMEM; | |
1761 | goto unacct_error; | |
1762 | } | |
1763 | ||
1764 | vma->vm_start = addr; | |
1765 | vma->vm_end = addr + len; | |
1766 | vma->vm_flags = vm_flags; | |
1767 | vma->vm_page_prot = vm_get_page_prot(vm_flags); | |
1768 | vma->vm_pgoff = pgoff; | |
1769 | ||
1770 | if (file) { | |
1771 | if (vm_flags & VM_DENYWRITE) { | |
1772 | error = deny_write_access(file); | |
1773 | if (error) | |
1774 | goto free_vma; | |
1775 | } | |
1776 | if (vm_flags & VM_SHARED) { | |
1777 | error = mapping_map_writable(file->f_mapping); | |
1778 | if (error) | |
1779 | goto allow_write_and_free_vma; | |
1780 | } | |
1781 | ||
1782 | /* ->mmap() can change vma->vm_file, but must guarantee that | |
1783 | * vma_link() below can deny write-access if VM_DENYWRITE is set | |
1784 | * and map writably if VM_SHARED is set. This usually means the | |
1785 | * new file must not have been exposed to user-space, yet. | |
1786 | */ | |
1787 | vma->vm_file = get_file(file); | |
1788 | error = call_mmap(file, vma); | |
1789 | if (error) | |
1790 | goto unmap_and_free_vma; | |
1791 | ||
1792 | /* Can addr have changed?? | |
1793 | * | |
1794 | * Answer: Yes, several device drivers can do it in their | |
1795 | * f_op->mmap method. -DaveM | |
1796 | * Bug: If addr is changed, prev, rb_link, rb_parent should | |
1797 | * be updated for vma_link() | |
1798 | */ | |
1799 | WARN_ON_ONCE(addr != vma->vm_start); | |
1800 | ||
1801 | addr = vma->vm_start; | |
1802 | vm_flags = vma->vm_flags; | |
1803 | } else if (vm_flags & VM_SHARED) { | |
1804 | error = shmem_zero_setup(vma); | |
1805 | if (error) | |
1806 | goto free_vma; | |
1807 | } else { | |
1808 | vma_set_anonymous(vma); | |
1809 | } | |
1810 | ||
1811 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
1812 | /* Once vma denies write, undo our temporary denial count */ | |
1813 | if (file) { | |
1814 | if (vm_flags & VM_SHARED) | |
1815 | mapping_unmap_writable(file->f_mapping); | |
1816 | if (vm_flags & VM_DENYWRITE) | |
1817 | allow_write_access(file); | |
1818 | } | |
1819 | file = vma->vm_file; | |
1820 | out: | |
1821 | perf_event_mmap(vma); | |
1822 | ||
1823 | vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); | |
1824 | if (vm_flags & VM_LOCKED) { | |
1825 | if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || | |
1826 | is_vm_hugetlb_page(vma) || | |
1827 | vma == get_gate_vma(current->mm)) | |
1828 | vma->vm_flags &= VM_LOCKED_CLEAR_MASK; | |
1829 | else | |
1830 | mm->locked_vm += (len >> PAGE_SHIFT); | |
1831 | } | |
1832 | ||
1833 | if (file) | |
1834 | uprobe_mmap(vma); | |
1835 | ||
1836 | /* | |
1837 | * New (or expanded) vma always get soft dirty status. | |
1838 | * Otherwise user-space soft-dirty page tracker won't | |
1839 | * be able to distinguish situation when vma area unmapped, | |
1840 | * then new mapped in-place (which must be aimed as | |
1841 | * a completely new data area). | |
1842 | */ | |
1843 | vma->vm_flags |= VM_SOFTDIRTY; | |
1844 | ||
1845 | vma_set_page_prot(vma); | |
1846 | ||
1847 | return addr; | |
1848 | ||
1849 | unmap_and_free_vma: | |
1850 | vma->vm_file = NULL; | |
1851 | fput(file); | |
1852 | ||
1853 | /* Undo any partial mapping done by a device driver. */ | |
1854 | unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); | |
1855 | charged = 0; | |
1856 | if (vm_flags & VM_SHARED) | |
1857 | mapping_unmap_writable(file->f_mapping); | |
1858 | allow_write_and_free_vma: | |
1859 | if (vm_flags & VM_DENYWRITE) | |
1860 | allow_write_access(file); | |
1861 | free_vma: | |
1862 | vm_area_free(vma); | |
1863 | unacct_error: | |
1864 | if (charged) | |
1865 | vm_unacct_memory(charged); | |
1866 | return error; | |
1867 | } | |
1868 | ||
1869 | unsigned long unmapped_area(struct vm_unmapped_area_info *info) | |
1870 | { | |
1871 | /* | |
1872 | * We implement the search by looking for an rbtree node that | |
1873 | * immediately follows a suitable gap. That is, | |
1874 | * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; | |
1875 | * - gap_end = vma->vm_start >= info->low_limit + length; | |
1876 | * - gap_end - gap_start >= length | |
1877 | */ | |
1878 | ||
1879 | struct mm_struct *mm = current->mm; | |
1880 | struct vm_area_struct *vma; | |
1881 | unsigned long length, low_limit, high_limit, gap_start, gap_end; | |
1882 | ||
1883 | /* Adjust search length to account for worst case alignment overhead */ | |
1884 | length = info->length + info->align_mask; | |
1885 | if (length < info->length) | |
1886 | return -ENOMEM; | |
1887 | ||
1888 | /* Adjust search limits by the desired length */ | |
1889 | if (info->high_limit < length) | |
1890 | return -ENOMEM; | |
1891 | high_limit = info->high_limit - length; | |
1892 | ||
1893 | if (info->low_limit > high_limit) | |
1894 | return -ENOMEM; | |
1895 | low_limit = info->low_limit + length; | |
1896 | ||
1897 | /* Check if rbtree root looks promising */ | |
1898 | if (RB_EMPTY_ROOT(&mm->mm_rb)) | |
1899 | goto check_highest; | |
1900 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); | |
1901 | if (vma->rb_subtree_gap < length) | |
1902 | goto check_highest; | |
1903 | ||
1904 | while (true) { | |
1905 | /* Visit left subtree if it looks promising */ | |
1906 | gap_end = vm_start_gap(vma); | |
1907 | if (gap_end >= low_limit && vma->vm_rb.rb_left) { | |
1908 | struct vm_area_struct *left = | |
1909 | rb_entry(vma->vm_rb.rb_left, | |
1910 | struct vm_area_struct, vm_rb); | |
1911 | if (left->rb_subtree_gap >= length) { | |
1912 | vma = left; | |
1913 | continue; | |
1914 | } | |
1915 | } | |
1916 | ||
1917 | gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; | |
1918 | check_current: | |
1919 | /* Check if current node has a suitable gap */ | |
1920 | if (gap_start > high_limit) | |
1921 | return -ENOMEM; | |
1922 | if (gap_end >= low_limit && | |
1923 | gap_end > gap_start && gap_end - gap_start >= length) | |
1924 | goto found; | |
1925 | ||
1926 | /* Visit right subtree if it looks promising */ | |
1927 | if (vma->vm_rb.rb_right) { | |
1928 | struct vm_area_struct *right = | |
1929 | rb_entry(vma->vm_rb.rb_right, | |
1930 | struct vm_area_struct, vm_rb); | |
1931 | if (right->rb_subtree_gap >= length) { | |
1932 | vma = right; | |
1933 | continue; | |
1934 | } | |
1935 | } | |
1936 | ||
1937 | /* Go back up the rbtree to find next candidate node */ | |
1938 | while (true) { | |
1939 | struct rb_node *prev = &vma->vm_rb; | |
1940 | if (!rb_parent(prev)) | |
1941 | goto check_highest; | |
1942 | vma = rb_entry(rb_parent(prev), | |
1943 | struct vm_area_struct, vm_rb); | |
1944 | if (prev == vma->vm_rb.rb_left) { | |
1945 | gap_start = vm_end_gap(vma->vm_prev); | |
1946 | gap_end = vm_start_gap(vma); | |
1947 | goto check_current; | |
1948 | } | |
1949 | } | |
1950 | } | |
1951 | ||
1952 | check_highest: | |
1953 | /* Check highest gap, which does not precede any rbtree node */ | |
1954 | gap_start = mm->highest_vm_end; | |
1955 | gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ | |
1956 | if (gap_start > high_limit) | |
1957 | return -ENOMEM; | |
1958 | ||
1959 | found: | |
1960 | /* We found a suitable gap. Clip it with the original low_limit. */ | |
1961 | if (gap_start < info->low_limit) | |
1962 | gap_start = info->low_limit; | |
1963 | ||
1964 | /* Adjust gap address to the desired alignment */ | |
1965 | gap_start += (info->align_offset - gap_start) & info->align_mask; | |
1966 | ||
1967 | VM_BUG_ON(gap_start + info->length > info->high_limit); | |
1968 | VM_BUG_ON(gap_start + info->length > gap_end); | |
1969 | return gap_start; | |
1970 | } | |
1971 | ||
1972 | unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) | |
1973 | { | |
1974 | struct mm_struct *mm = current->mm; | |
1975 | struct vm_area_struct *vma; | |
1976 | unsigned long length, low_limit, high_limit, gap_start, gap_end; | |
1977 | ||
1978 | /* Adjust search length to account for worst case alignment overhead */ | |
1979 | length = info->length + info->align_mask; | |
1980 | if (length < info->length) | |
1981 | return -ENOMEM; | |
1982 | ||
1983 | /* | |
1984 | * Adjust search limits by the desired length. | |
1985 | * See implementation comment at top of unmapped_area(). | |
1986 | */ | |
1987 | gap_end = info->high_limit; | |
1988 | if (gap_end < length) | |
1989 | return -ENOMEM; | |
1990 | high_limit = gap_end - length; | |
1991 | ||
1992 | if (info->low_limit > high_limit) | |
1993 | return -ENOMEM; | |
1994 | low_limit = info->low_limit + length; | |
1995 | ||
1996 | /* Check highest gap, which does not precede any rbtree node */ | |
1997 | gap_start = mm->highest_vm_end; | |
1998 | if (gap_start <= high_limit) | |
1999 | goto found_highest; | |
2000 | ||
2001 | /* Check if rbtree root looks promising */ | |
2002 | if (RB_EMPTY_ROOT(&mm->mm_rb)) | |
2003 | return -ENOMEM; | |
2004 | vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); | |
2005 | if (vma->rb_subtree_gap < length) | |
2006 | return -ENOMEM; | |
2007 | ||
2008 | while (true) { | |
2009 | /* Visit right subtree if it looks promising */ | |
2010 | gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; | |
2011 | if (gap_start <= high_limit && vma->vm_rb.rb_right) { | |
2012 | struct vm_area_struct *right = | |
2013 | rb_entry(vma->vm_rb.rb_right, | |
2014 | struct vm_area_struct, vm_rb); | |
2015 | if (right->rb_subtree_gap >= length) { | |
2016 | vma = right; | |
2017 | continue; | |
2018 | } | |
2019 | } | |
2020 | ||
2021 | check_current: | |
2022 | /* Check if current node has a suitable gap */ | |
2023 | gap_end = vm_start_gap(vma); | |
2024 | if (gap_end < low_limit) | |
2025 | return -ENOMEM; | |
2026 | if (gap_start <= high_limit && | |
2027 | gap_end > gap_start && gap_end - gap_start >= length) | |
2028 | goto found; | |
2029 | ||
2030 | /* Visit left subtree if it looks promising */ | |
2031 | if (vma->vm_rb.rb_left) { | |
2032 | struct vm_area_struct *left = | |
2033 | rb_entry(vma->vm_rb.rb_left, | |
2034 | struct vm_area_struct, vm_rb); | |
2035 | if (left->rb_subtree_gap >= length) { | |
2036 | vma = left; | |
2037 | continue; | |
2038 | } | |
2039 | } | |
2040 | ||
2041 | /* Go back up the rbtree to find next candidate node */ | |
2042 | while (true) { | |
2043 | struct rb_node *prev = &vma->vm_rb; | |
2044 | if (!rb_parent(prev)) | |
2045 | return -ENOMEM; | |
2046 | vma = rb_entry(rb_parent(prev), | |
2047 | struct vm_area_struct, vm_rb); | |
2048 | if (prev == vma->vm_rb.rb_right) { | |
2049 | gap_start = vma->vm_prev ? | |
2050 | vm_end_gap(vma->vm_prev) : 0; | |
2051 | goto check_current; | |
2052 | } | |
2053 | } | |
2054 | } | |
2055 | ||
2056 | found: | |
2057 | /* We found a suitable gap. Clip it with the original high_limit. */ | |
2058 | if (gap_end > info->high_limit) | |
2059 | gap_end = info->high_limit; | |
2060 | ||
2061 | found_highest: | |
2062 | /* Compute highest gap address at the desired alignment */ | |
2063 | gap_end -= info->length; | |
2064 | gap_end -= (gap_end - info->align_offset) & info->align_mask; | |
2065 | ||
2066 | VM_BUG_ON(gap_end < info->low_limit); | |
2067 | VM_BUG_ON(gap_end < gap_start); | |
2068 | return gap_end; | |
2069 | } | |
2070 | ||
2071 | ||
2072 | #ifndef arch_get_mmap_end | |
2073 | #define arch_get_mmap_end(addr) (TASK_SIZE) | |
2074 | #endif | |
2075 | ||
2076 | #ifndef arch_get_mmap_base | |
2077 | #define arch_get_mmap_base(addr, base) (base) | |
2078 | #endif | |
2079 | ||
2080 | /* Get an address range which is currently unmapped. | |
2081 | * For shmat() with addr=0. | |
2082 | * | |
2083 | * Ugly calling convention alert: | |
2084 | * Return value with the low bits set means error value, | |
2085 | * ie | |
2086 | * if (ret & ~PAGE_MASK) | |
2087 | * error = ret; | |
2088 | * | |
2089 | * This function "knows" that -ENOMEM has the bits set. | |
2090 | */ | |
2091 | #ifndef HAVE_ARCH_UNMAPPED_AREA | |
2092 | unsigned long | |
2093 | arch_get_unmapped_area(struct file *filp, unsigned long addr, | |
2094 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
2095 | { | |
2096 | struct mm_struct *mm = current->mm; | |
2097 | struct vm_area_struct *vma, *prev; | |
2098 | struct vm_unmapped_area_info info; | |
2099 | const unsigned long mmap_end = arch_get_mmap_end(addr); | |
2100 | ||
2101 | if (len > mmap_end - mmap_min_addr) | |
2102 | return -ENOMEM; | |
2103 | ||
2104 | if (flags & MAP_FIXED) | |
2105 | return addr; | |
2106 | ||
2107 | if (addr) { | |
2108 | addr = PAGE_ALIGN(addr); | |
2109 | vma = find_vma_prev(mm, addr, &prev); | |
2110 | if (mmap_end - len >= addr && addr >= mmap_min_addr && | |
2111 | (!vma || addr + len <= vm_start_gap(vma)) && | |
2112 | (!prev || addr >= vm_end_gap(prev))) | |
2113 | return addr; | |
2114 | } | |
2115 | ||
2116 | info.flags = 0; | |
2117 | info.length = len; | |
2118 | info.low_limit = mm->mmap_base; | |
2119 | info.high_limit = mmap_end; | |
2120 | info.align_mask = 0; | |
2121 | return vm_unmapped_area(&info); | |
2122 | } | |
2123 | #endif | |
2124 | ||
2125 | /* | |
2126 | * This mmap-allocator allocates new areas top-down from below the | |
2127 | * stack's low limit (the base): | |
2128 | */ | |
2129 | #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN | |
2130 | unsigned long | |
2131 | arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, | |
2132 | unsigned long len, unsigned long pgoff, | |
2133 | unsigned long flags) | |
2134 | { | |
2135 | struct vm_area_struct *vma, *prev; | |
2136 | struct mm_struct *mm = current->mm; | |
2137 | struct vm_unmapped_area_info info; | |
2138 | const unsigned long mmap_end = arch_get_mmap_end(addr); | |
2139 | ||
2140 | /* requested length too big for entire address space */ | |
2141 | if (len > mmap_end - mmap_min_addr) | |
2142 | return -ENOMEM; | |
2143 | ||
2144 | if (flags & MAP_FIXED) | |
2145 | return addr; | |
2146 | ||
2147 | /* requesting a specific address */ | |
2148 | if (addr) { | |
2149 | addr = PAGE_ALIGN(addr); | |
2150 | vma = find_vma_prev(mm, addr, &prev); | |
2151 | if (mmap_end - len >= addr && addr >= mmap_min_addr && | |
2152 | (!vma || addr + len <= vm_start_gap(vma)) && | |
2153 | (!prev || addr >= vm_end_gap(prev))) | |
2154 | return addr; | |
2155 | } | |
2156 | ||
2157 | info.flags = VM_UNMAPPED_AREA_TOPDOWN; | |
2158 | info.length = len; | |
2159 | info.low_limit = max(PAGE_SIZE, mmap_min_addr); | |
2160 | info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); | |
2161 | info.align_mask = 0; | |
2162 | addr = vm_unmapped_area(&info); | |
2163 | ||
2164 | /* | |
2165 | * A failed mmap() very likely causes application failure, | |
2166 | * so fall back to the bottom-up function here. This scenario | |
2167 | * can happen with large stack limits and large mmap() | |
2168 | * allocations. | |
2169 | */ | |
2170 | if (offset_in_page(addr)) { | |
2171 | VM_BUG_ON(addr != -ENOMEM); | |
2172 | info.flags = 0; | |
2173 | info.low_limit = TASK_UNMAPPED_BASE; | |
2174 | info.high_limit = mmap_end; | |
2175 | addr = vm_unmapped_area(&info); | |
2176 | } | |
2177 | ||
2178 | return addr; | |
2179 | } | |
2180 | #endif | |
2181 | ||
2182 | unsigned long | |
2183 | get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, | |
2184 | unsigned long pgoff, unsigned long flags) | |
2185 | { | |
2186 | unsigned long (*get_area)(struct file *, unsigned long, | |
2187 | unsigned long, unsigned long, unsigned long); | |
2188 | ||
2189 | unsigned long error = arch_mmap_check(addr, len, flags); | |
2190 | if (error) | |
2191 | return error; | |
2192 | ||
2193 | /* Careful about overflows.. */ | |
2194 | if (len > TASK_SIZE) | |
2195 | return -ENOMEM; | |
2196 | ||
2197 | get_area = current->mm->get_unmapped_area; | |
2198 | if (file) { | |
2199 | if (file->f_op->get_unmapped_area) | |
2200 | get_area = file->f_op->get_unmapped_area; | |
2201 | } else if (flags & MAP_SHARED) { | |
2202 | /* | |
2203 | * mmap_region() will call shmem_zero_setup() to create a file, | |
2204 | * so use shmem's get_unmapped_area in case it can be huge. | |
2205 | * do_mmap_pgoff() will clear pgoff, so match alignment. | |
2206 | */ | |
2207 | pgoff = 0; | |
2208 | get_area = shmem_get_unmapped_area; | |
2209 | } | |
2210 | ||
2211 | addr = get_area(file, addr, len, pgoff, flags); | |
2212 | if (IS_ERR_VALUE(addr)) | |
2213 | return addr; | |
2214 | ||
2215 | if (addr > TASK_SIZE - len) | |
2216 | return -ENOMEM; | |
2217 | if (offset_in_page(addr)) | |
2218 | return -EINVAL; | |
2219 | ||
2220 | error = security_mmap_addr(addr); | |
2221 | return error ? error : addr; | |
2222 | } | |
2223 | ||
2224 | EXPORT_SYMBOL(get_unmapped_area); | |
2225 | ||
2226 | /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ | |
2227 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) | |
2228 | { | |
2229 | struct rb_node *rb_node; | |
2230 | struct vm_area_struct *vma; | |
2231 | ||
2232 | /* Check the cache first. */ | |
2233 | vma = vmacache_find(mm, addr); | |
2234 | if (likely(vma)) | |
2235 | return vma; | |
2236 | ||
2237 | rb_node = mm->mm_rb.rb_node; | |
2238 | ||
2239 | while (rb_node) { | |
2240 | struct vm_area_struct *tmp; | |
2241 | ||
2242 | tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); | |
2243 | ||
2244 | if (tmp->vm_end > addr) { | |
2245 | vma = tmp; | |
2246 | if (tmp->vm_start <= addr) | |
2247 | break; | |
2248 | rb_node = rb_node->rb_left; | |
2249 | } else | |
2250 | rb_node = rb_node->rb_right; | |
2251 | } | |
2252 | ||
2253 | if (vma) | |
2254 | vmacache_update(addr, vma); | |
2255 | return vma; | |
2256 | } | |
2257 | ||
2258 | EXPORT_SYMBOL(find_vma); | |
2259 | ||
2260 | /* | |
2261 | * Same as find_vma, but also return a pointer to the previous VMA in *pprev. | |
2262 | */ | |
2263 | struct vm_area_struct * | |
2264 | find_vma_prev(struct mm_struct *mm, unsigned long addr, | |
2265 | struct vm_area_struct **pprev) | |
2266 | { | |
2267 | struct vm_area_struct *vma; | |
2268 | ||
2269 | vma = find_vma(mm, addr); | |
2270 | if (vma) { | |
2271 | *pprev = vma->vm_prev; | |
2272 | } else { | |
2273 | struct rb_node *rb_node = mm->mm_rb.rb_node; | |
2274 | *pprev = NULL; | |
2275 | while (rb_node) { | |
2276 | *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); | |
2277 | rb_node = rb_node->rb_right; | |
2278 | } | |
2279 | } | |
2280 | return vma; | |
2281 | } | |
2282 | ||
2283 | /* | |
2284 | * Verify that the stack growth is acceptable and | |
2285 | * update accounting. This is shared with both the | |
2286 | * grow-up and grow-down cases. | |
2287 | */ | |
2288 | static int acct_stack_growth(struct vm_area_struct *vma, | |
2289 | unsigned long size, unsigned long grow) | |
2290 | { | |
2291 | struct mm_struct *mm = vma->vm_mm; | |
2292 | unsigned long new_start; | |
2293 | ||
2294 | /* address space limit tests */ | |
2295 | if (!may_expand_vm(mm, vma->vm_flags, grow)) | |
2296 | return -ENOMEM; | |
2297 | ||
2298 | /* Stack limit test */ | |
2299 | if (size > rlimit(RLIMIT_STACK)) | |
2300 | return -ENOMEM; | |
2301 | ||
2302 | /* mlock limit tests */ | |
2303 | if (vma->vm_flags & VM_LOCKED) { | |
2304 | unsigned long locked; | |
2305 | unsigned long limit; | |
2306 | locked = mm->locked_vm + grow; | |
2307 | limit = rlimit(RLIMIT_MEMLOCK); | |
2308 | limit >>= PAGE_SHIFT; | |
2309 | if (locked > limit && !capable(CAP_IPC_LOCK)) | |
2310 | return -ENOMEM; | |
2311 | } | |
2312 | ||
2313 | /* Check to ensure the stack will not grow into a hugetlb-only region */ | |
2314 | new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : | |
2315 | vma->vm_end - size; | |
2316 | if (is_hugepage_only_range(vma->vm_mm, new_start, size)) | |
2317 | return -EFAULT; | |
2318 | ||
2319 | /* | |
2320 | * Overcommit.. This must be the final test, as it will | |
2321 | * update security statistics. | |
2322 | */ | |
2323 | if (security_vm_enough_memory_mm(mm, grow)) | |
2324 | return -ENOMEM; | |
2325 | ||
2326 | return 0; | |
2327 | } | |
2328 | ||
2329 | #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) | |
2330 | /* | |
2331 | * PA-RISC uses this for its stack; IA64 for its Register Backing Store. | |
2332 | * vma is the last one with address > vma->vm_end. Have to extend vma. | |
2333 | */ | |
2334 | int expand_upwards(struct vm_area_struct *vma, unsigned long address) | |
2335 | { | |
2336 | struct mm_struct *mm = vma->vm_mm; | |
2337 | struct vm_area_struct *next; | |
2338 | unsigned long gap_addr; | |
2339 | int error = 0; | |
2340 | ||
2341 | if (!(vma->vm_flags & VM_GROWSUP)) | |
2342 | return -EFAULT; | |
2343 | ||
2344 | /* Guard against exceeding limits of the address space. */ | |
2345 | address &= PAGE_MASK; | |
2346 | if (address >= (TASK_SIZE & PAGE_MASK)) | |
2347 | return -ENOMEM; | |
2348 | address += PAGE_SIZE; | |
2349 | ||
2350 | /* Enforce stack_guard_gap */ | |
2351 | gap_addr = address + stack_guard_gap; | |
2352 | ||
2353 | /* Guard against overflow */ | |
2354 | if (gap_addr < address || gap_addr > TASK_SIZE) | |
2355 | gap_addr = TASK_SIZE; | |
2356 | ||
2357 | next = vma->vm_next; | |
2358 | if (next && next->vm_start < gap_addr && | |
2359 | (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) { | |
2360 | if (!(next->vm_flags & VM_GROWSUP)) | |
2361 | return -ENOMEM; | |
2362 | /* Check that both stack segments have the same anon_vma? */ | |
2363 | } | |
2364 | ||
2365 | /* We must make sure the anon_vma is allocated. */ | |
2366 | if (unlikely(anon_vma_prepare(vma))) | |
2367 | return -ENOMEM; | |
2368 | ||
2369 | /* | |
2370 | * vma->vm_start/vm_end cannot change under us because the caller | |
2371 | * is required to hold the mmap_sem in read mode. We need the | |
2372 | * anon_vma lock to serialize against concurrent expand_stacks. | |
2373 | */ | |
2374 | anon_vma_lock_write(vma->anon_vma); | |
2375 | ||
2376 | /* Somebody else might have raced and expanded it already */ | |
2377 | if (address > vma->vm_end) { | |
2378 | unsigned long size, grow; | |
2379 | ||
2380 | size = address - vma->vm_start; | |
2381 | grow = (address - vma->vm_end) >> PAGE_SHIFT; | |
2382 | ||
2383 | error = -ENOMEM; | |
2384 | if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { | |
2385 | error = acct_stack_growth(vma, size, grow); | |
2386 | if (!error) { | |
2387 | /* | |
2388 | * vma_gap_update() doesn't support concurrent | |
2389 | * updates, but we only hold a shared mmap_sem | |
2390 | * lock here, so we need to protect against | |
2391 | * concurrent vma expansions. | |
2392 | * anon_vma_lock_write() doesn't help here, as | |
2393 | * we don't guarantee that all growable vmas | |
2394 | * in a mm share the same root anon vma. | |
2395 | * So, we reuse mm->page_table_lock to guard | |
2396 | * against concurrent vma expansions. | |
2397 | */ | |
2398 | spin_lock(&mm->page_table_lock); | |
2399 | if (vma->vm_flags & VM_LOCKED) | |
2400 | mm->locked_vm += grow; | |
2401 | vm_stat_account(mm, vma->vm_flags, grow); | |
2402 | anon_vma_interval_tree_pre_update_vma(vma); | |
2403 | vma->vm_end = address; | |
2404 | anon_vma_interval_tree_post_update_vma(vma); | |
2405 | if (vma->vm_next) | |
2406 | vma_gap_update(vma->vm_next); | |
2407 | else | |
2408 | mm->highest_vm_end = vm_end_gap(vma); | |
2409 | spin_unlock(&mm->page_table_lock); | |
2410 | ||
2411 | perf_event_mmap(vma); | |
2412 | } | |
2413 | } | |
2414 | } | |
2415 | anon_vma_unlock_write(vma->anon_vma); | |
2416 | khugepaged_enter_vma_merge(vma, vma->vm_flags); | |
2417 | validate_mm(mm); | |
2418 | return error; | |
2419 | } | |
2420 | #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ | |
2421 | ||
2422 | /* | |
2423 | * vma is the first one with address < vma->vm_start. Have to extend vma. | |
2424 | */ | |
2425 | int expand_downwards(struct vm_area_struct *vma, | |
2426 | unsigned long address) | |
2427 | { | |
2428 | struct mm_struct *mm = vma->vm_mm; | |
2429 | struct vm_area_struct *prev; | |
2430 | int error = 0; | |
2431 | ||
2432 | address &= PAGE_MASK; | |
2433 | if (address < mmap_min_addr) | |
2434 | return -EPERM; | |
2435 | ||
2436 | /* Enforce stack_guard_gap */ | |
2437 | prev = vma->vm_prev; | |
2438 | /* Check that both stack segments have the same anon_vma? */ | |
2439 | if (prev && !(prev->vm_flags & VM_GROWSDOWN) && | |
2440 | (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) { | |
2441 | if (address - prev->vm_end < stack_guard_gap) | |
2442 | return -ENOMEM; | |
2443 | } | |
2444 | ||
2445 | /* We must make sure the anon_vma is allocated. */ | |
2446 | if (unlikely(anon_vma_prepare(vma))) | |
2447 | return -ENOMEM; | |
2448 | ||
2449 | /* | |
2450 | * vma->vm_start/vm_end cannot change under us because the caller | |
2451 | * is required to hold the mmap_sem in read mode. We need the | |
2452 | * anon_vma lock to serialize against concurrent expand_stacks. | |
2453 | */ | |
2454 | anon_vma_lock_write(vma->anon_vma); | |
2455 | ||
2456 | /* Somebody else might have raced and expanded it already */ | |
2457 | if (address < vma->vm_start) { | |
2458 | unsigned long size, grow; | |
2459 | ||
2460 | size = vma->vm_end - address; | |
2461 | grow = (vma->vm_start - address) >> PAGE_SHIFT; | |
2462 | ||
2463 | error = -ENOMEM; | |
2464 | if (grow <= vma->vm_pgoff) { | |
2465 | error = acct_stack_growth(vma, size, grow); | |
2466 | if (!error) { | |
2467 | /* | |
2468 | * vma_gap_update() doesn't support concurrent | |
2469 | * updates, but we only hold a shared mmap_sem | |
2470 | * lock here, so we need to protect against | |
2471 | * concurrent vma expansions. | |
2472 | * anon_vma_lock_write() doesn't help here, as | |
2473 | * we don't guarantee that all growable vmas | |
2474 | * in a mm share the same root anon vma. | |
2475 | * So, we reuse mm->page_table_lock to guard | |
2476 | * against concurrent vma expansions. | |
2477 | */ | |
2478 | spin_lock(&mm->page_table_lock); | |
2479 | if (vma->vm_flags & VM_LOCKED) | |
2480 | mm->locked_vm += grow; | |
2481 | vm_stat_account(mm, vma->vm_flags, grow); | |
2482 | anon_vma_interval_tree_pre_update_vma(vma); | |
2483 | vma->vm_start = address; | |
2484 | vma->vm_pgoff -= grow; | |
2485 | anon_vma_interval_tree_post_update_vma(vma); | |
2486 | vma_gap_update(vma); | |
2487 | spin_unlock(&mm->page_table_lock); | |
2488 | ||
2489 | perf_event_mmap(vma); | |
2490 | } | |
2491 | } | |
2492 | } | |
2493 | anon_vma_unlock_write(vma->anon_vma); | |
2494 | khugepaged_enter_vma_merge(vma, vma->vm_flags); | |
2495 | validate_mm(mm); | |
2496 | return error; | |
2497 | } | |
2498 | ||
2499 | /* enforced gap between the expanding stack and other mappings. */ | |
2500 | unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; | |
2501 | ||
2502 | static int __init cmdline_parse_stack_guard_gap(char *p) | |
2503 | { | |
2504 | unsigned long val; | |
2505 | char *endptr; | |
2506 | ||
2507 | val = simple_strtoul(p, &endptr, 10); | |
2508 | if (!*endptr) | |
2509 | stack_guard_gap = val << PAGE_SHIFT; | |
2510 | ||
2511 | return 0; | |
2512 | } | |
2513 | __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); | |
2514 | ||
2515 | #ifdef CONFIG_STACK_GROWSUP | |
2516 | int expand_stack(struct vm_area_struct *vma, unsigned long address) | |
2517 | { | |
2518 | return expand_upwards(vma, address); | |
2519 | } | |
2520 | ||
2521 | struct vm_area_struct * | |
2522 | find_extend_vma(struct mm_struct *mm, unsigned long addr) | |
2523 | { | |
2524 | struct vm_area_struct *vma, *prev; | |
2525 | ||
2526 | addr &= PAGE_MASK; | |
2527 | vma = find_vma_prev(mm, addr, &prev); | |
2528 | if (vma && (vma->vm_start <= addr)) | |
2529 | return vma; | |
2530 | /* don't alter vm_end if the coredump is running */ | |
2531 | if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr)) | |
2532 | return NULL; | |
2533 | if (prev->vm_flags & VM_LOCKED) | |
2534 | populate_vma_page_range(prev, addr, prev->vm_end, NULL); | |
2535 | return prev; | |
2536 | } | |
2537 | #else | |
2538 | int expand_stack(struct vm_area_struct *vma, unsigned long address) | |
2539 | { | |
2540 | return expand_downwards(vma, address); | |
2541 | } | |
2542 | ||
2543 | struct vm_area_struct * | |
2544 | find_extend_vma(struct mm_struct *mm, unsigned long addr) | |
2545 | { | |
2546 | struct vm_area_struct *vma; | |
2547 | unsigned long start; | |
2548 | ||
2549 | addr &= PAGE_MASK; | |
2550 | vma = find_vma(mm, addr); | |
2551 | if (!vma) | |
2552 | return NULL; | |
2553 | if (vma->vm_start <= addr) | |
2554 | return vma; | |
2555 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
2556 | return NULL; | |
2557 | /* don't alter vm_start if the coredump is running */ | |
2558 | if (!mmget_still_valid(mm)) | |
2559 | return NULL; | |
2560 | start = vma->vm_start; | |
2561 | if (expand_stack(vma, addr)) | |
2562 | return NULL; | |
2563 | if (vma->vm_flags & VM_LOCKED) | |
2564 | populate_vma_page_range(vma, addr, start, NULL); | |
2565 | return vma; | |
2566 | } | |
2567 | #endif | |
2568 | ||
2569 | EXPORT_SYMBOL_GPL(find_extend_vma); | |
2570 | ||
2571 | /* | |
2572 | * Ok - we have the memory areas we should free on the vma list, | |
2573 | * so release them, and do the vma updates. | |
2574 | * | |
2575 | * Called with the mm semaphore held. | |
2576 | */ | |
2577 | static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) | |
2578 | { | |
2579 | unsigned long nr_accounted = 0; | |
2580 | ||
2581 | /* Update high watermark before we lower total_vm */ | |
2582 | update_hiwater_vm(mm); | |
2583 | do { | |
2584 | long nrpages = vma_pages(vma); | |
2585 | ||
2586 | if (vma->vm_flags & VM_ACCOUNT) | |
2587 | nr_accounted += nrpages; | |
2588 | vm_stat_account(mm, vma->vm_flags, -nrpages); | |
2589 | vma = remove_vma(vma); | |
2590 | } while (vma); | |
2591 | vm_unacct_memory(nr_accounted); | |
2592 | validate_mm(mm); | |
2593 | } | |
2594 | ||
2595 | /* | |
2596 | * Get rid of page table information in the indicated region. | |
2597 | * | |
2598 | * Called with the mm semaphore held. | |
2599 | */ | |
2600 | static void unmap_region(struct mm_struct *mm, | |
2601 | struct vm_area_struct *vma, struct vm_area_struct *prev, | |
2602 | unsigned long start, unsigned long end) | |
2603 | { | |
2604 | struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap; | |
2605 | struct mmu_gather tlb; | |
2606 | ||
2607 | lru_add_drain(); | |
2608 | tlb_gather_mmu(&tlb, mm, start, end); | |
2609 | update_hiwater_rss(mm); | |
2610 | unmap_vmas(&tlb, vma, start, end); | |
2611 | free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, | |
2612 | next ? next->vm_start : USER_PGTABLES_CEILING); | |
2613 | tlb_finish_mmu(&tlb, start, end); | |
2614 | } | |
2615 | ||
2616 | /* | |
2617 | * Create a list of vma's touched by the unmap, removing them from the mm's | |
2618 | * vma list as we go.. | |
2619 | */ | |
2620 | static void | |
2621 | detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, | |
2622 | struct vm_area_struct *prev, unsigned long end) | |
2623 | { | |
2624 | struct vm_area_struct **insertion_point; | |
2625 | struct vm_area_struct *tail_vma = NULL; | |
2626 | ||
2627 | insertion_point = (prev ? &prev->vm_next : &mm->mmap); | |
2628 | vma->vm_prev = NULL; | |
2629 | do { | |
2630 | vma_rb_erase(vma, &mm->mm_rb); | |
2631 | mm->map_count--; | |
2632 | tail_vma = vma; | |
2633 | vma = vma->vm_next; | |
2634 | } while (vma && vma->vm_start < end); | |
2635 | *insertion_point = vma; | |
2636 | if (vma) { | |
2637 | vma->vm_prev = prev; | |
2638 | vma_gap_update(vma); | |
2639 | } else | |
2640 | mm->highest_vm_end = prev ? vm_end_gap(prev) : 0; | |
2641 | tail_vma->vm_next = NULL; | |
2642 | ||
2643 | /* Kill the cache */ | |
2644 | vmacache_invalidate(mm); | |
2645 | } | |
2646 | ||
2647 | /* | |
2648 | * __split_vma() bypasses sysctl_max_map_count checking. We use this where it | |
2649 | * has already been checked or doesn't make sense to fail. | |
2650 | */ | |
2651 | int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, | |
2652 | unsigned long addr, int new_below) | |
2653 | { | |
2654 | struct vm_area_struct *new; | |
2655 | int err; | |
2656 | ||
2657 | if (vma->vm_ops && vma->vm_ops->split) { | |
2658 | err = vma->vm_ops->split(vma, addr); | |
2659 | if (err) | |
2660 | return err; | |
2661 | } | |
2662 | ||
2663 | new = vm_area_dup(vma); | |
2664 | if (!new) | |
2665 | return -ENOMEM; | |
2666 | ||
2667 | if (new_below) | |
2668 | new->vm_end = addr; | |
2669 | else { | |
2670 | new->vm_start = addr; | |
2671 | new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); | |
2672 | } | |
2673 | ||
2674 | err = vma_dup_policy(vma, new); | |
2675 | if (err) | |
2676 | goto out_free_vma; | |
2677 | ||
2678 | err = anon_vma_clone(new, vma); | |
2679 | if (err) | |
2680 | goto out_free_mpol; | |
2681 | ||
2682 | if (new->vm_file) | |
2683 | get_file(new->vm_file); | |
2684 | ||
2685 | if (new->vm_ops && new->vm_ops->open) | |
2686 | new->vm_ops->open(new); | |
2687 | ||
2688 | if (new_below) | |
2689 | err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + | |
2690 | ((addr - new->vm_start) >> PAGE_SHIFT), new); | |
2691 | else | |
2692 | err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); | |
2693 | ||
2694 | /* Success. */ | |
2695 | if (!err) | |
2696 | return 0; | |
2697 | ||
2698 | /* Clean everything up if vma_adjust failed. */ | |
2699 | if (new->vm_ops && new->vm_ops->close) | |
2700 | new->vm_ops->close(new); | |
2701 | if (new->vm_file) | |
2702 | fput(new->vm_file); | |
2703 | unlink_anon_vmas(new); | |
2704 | out_free_mpol: | |
2705 | mpol_put(vma_policy(new)); | |
2706 | out_free_vma: | |
2707 | vm_area_free(new); | |
2708 | return err; | |
2709 | } | |
2710 | ||
2711 | /* | |
2712 | * Split a vma into two pieces at address 'addr', a new vma is allocated | |
2713 | * either for the first part or the tail. | |
2714 | */ | |
2715 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, | |
2716 | unsigned long addr, int new_below) | |
2717 | { | |
2718 | if (mm->map_count >= sysctl_max_map_count) | |
2719 | return -ENOMEM; | |
2720 | ||
2721 | return __split_vma(mm, vma, addr, new_below); | |
2722 | } | |
2723 | ||
2724 | /* Munmap is split into 2 main parts -- this part which finds | |
2725 | * what needs doing, and the areas themselves, which do the | |
2726 | * work. This now handles partial unmappings. | |
2727 | * Jeremy Fitzhardinge <jeremy@goop.org> | |
2728 | */ | |
2729 | int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len, | |
2730 | struct list_head *uf, bool downgrade) | |
2731 | { | |
2732 | unsigned long end; | |
2733 | struct vm_area_struct *vma, *prev, *last; | |
2734 | ||
2735 | if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) | |
2736 | return -EINVAL; | |
2737 | ||
2738 | len = PAGE_ALIGN(len); | |
2739 | end = start + len; | |
2740 | if (len == 0) | |
2741 | return -EINVAL; | |
2742 | ||
2743 | /* | |
2744 | * arch_unmap() might do unmaps itself. It must be called | |
2745 | * and finish any rbtree manipulation before this code | |
2746 | * runs and also starts to manipulate the rbtree. | |
2747 | */ | |
2748 | arch_unmap(mm, start, end); | |
2749 | ||
2750 | /* Find the first overlapping VMA */ | |
2751 | vma = find_vma(mm, start); | |
2752 | if (!vma) | |
2753 | return 0; | |
2754 | prev = vma->vm_prev; | |
2755 | /* we have start < vma->vm_end */ | |
2756 | ||
2757 | /* if it doesn't overlap, we have nothing.. */ | |
2758 | if (vma->vm_start >= end) | |
2759 | return 0; | |
2760 | ||
2761 | /* | |
2762 | * If we need to split any vma, do it now to save pain later. | |
2763 | * | |
2764 | * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially | |
2765 | * unmapped vm_area_struct will remain in use: so lower split_vma | |
2766 | * places tmp vma above, and higher split_vma places tmp vma below. | |
2767 | */ | |
2768 | if (start > vma->vm_start) { | |
2769 | int error; | |
2770 | ||
2771 | /* | |
2772 | * Make sure that map_count on return from munmap() will | |
2773 | * not exceed its limit; but let map_count go just above | |
2774 | * its limit temporarily, to help free resources as expected. | |
2775 | */ | |
2776 | if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) | |
2777 | return -ENOMEM; | |
2778 | ||
2779 | error = __split_vma(mm, vma, start, 0); | |
2780 | if (error) | |
2781 | return error; | |
2782 | prev = vma; | |
2783 | } | |
2784 | ||
2785 | /* Does it split the last one? */ | |
2786 | last = find_vma(mm, end); | |
2787 | if (last && end > last->vm_start) { | |
2788 | int error = __split_vma(mm, last, end, 1); | |
2789 | if (error) | |
2790 | return error; | |
2791 | } | |
2792 | vma = prev ? prev->vm_next : mm->mmap; | |
2793 | ||
2794 | if (unlikely(uf)) { | |
2795 | /* | |
2796 | * If userfaultfd_unmap_prep returns an error the vmas | |
2797 | * will remain splitted, but userland will get a | |
2798 | * highly unexpected error anyway. This is no | |
2799 | * different than the case where the first of the two | |
2800 | * __split_vma fails, but we don't undo the first | |
2801 | * split, despite we could. This is unlikely enough | |
2802 | * failure that it's not worth optimizing it for. | |
2803 | */ | |
2804 | int error = userfaultfd_unmap_prep(vma, start, end, uf); | |
2805 | if (error) | |
2806 | return error; | |
2807 | } | |
2808 | ||
2809 | /* | |
2810 | * unlock any mlock()ed ranges before detaching vmas | |
2811 | */ | |
2812 | if (mm->locked_vm) { | |
2813 | struct vm_area_struct *tmp = vma; | |
2814 | while (tmp && tmp->vm_start < end) { | |
2815 | if (tmp->vm_flags & VM_LOCKED) { | |
2816 | mm->locked_vm -= vma_pages(tmp); | |
2817 | munlock_vma_pages_all(tmp); | |
2818 | } | |
2819 | ||
2820 | tmp = tmp->vm_next; | |
2821 | } | |
2822 | } | |
2823 | ||
2824 | /* Detach vmas from rbtree */ | |
2825 | detach_vmas_to_be_unmapped(mm, vma, prev, end); | |
2826 | ||
2827 | if (downgrade) | |
2828 | downgrade_write(&mm->mmap_sem); | |
2829 | ||
2830 | unmap_region(mm, vma, prev, start, end); | |
2831 | ||
2832 | /* Fix up all other VM information */ | |
2833 | remove_vma_list(mm, vma); | |
2834 | ||
2835 | return downgrade ? 1 : 0; | |
2836 | } | |
2837 | ||
2838 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, | |
2839 | struct list_head *uf) | |
2840 | { | |
2841 | return __do_munmap(mm, start, len, uf, false); | |
2842 | } | |
2843 | ||
2844 | static int __vm_munmap(unsigned long start, size_t len, bool downgrade) | |
2845 | { | |
2846 | int ret; | |
2847 | struct mm_struct *mm = current->mm; | |
2848 | LIST_HEAD(uf); | |
2849 | ||
2850 | if (down_write_killable(&mm->mmap_sem)) | |
2851 | return -EINTR; | |
2852 | ||
2853 | ret = __do_munmap(mm, start, len, &uf, downgrade); | |
2854 | /* | |
2855 | * Returning 1 indicates mmap_sem is downgraded. | |
2856 | * But 1 is not legal return value of vm_munmap() and munmap(), reset | |
2857 | * it to 0 before return. | |
2858 | */ | |
2859 | if (ret == 1) { | |
2860 | up_read(&mm->mmap_sem); | |
2861 | ret = 0; | |
2862 | } else | |
2863 | up_write(&mm->mmap_sem); | |
2864 | ||
2865 | userfaultfd_unmap_complete(mm, &uf); | |
2866 | return ret; | |
2867 | } | |
2868 | ||
2869 | int vm_munmap(unsigned long start, size_t len) | |
2870 | { | |
2871 | return __vm_munmap(start, len, false); | |
2872 | } | |
2873 | EXPORT_SYMBOL(vm_munmap); | |
2874 | ||
2875 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) | |
2876 | { | |
2877 | profile_munmap(addr); | |
2878 | return __vm_munmap(addr, len, true); | |
2879 | } | |
2880 | ||
2881 | ||
2882 | /* | |
2883 | * Emulation of deprecated remap_file_pages() syscall. | |
2884 | */ | |
2885 | SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, | |
2886 | unsigned long, prot, unsigned long, pgoff, unsigned long, flags) | |
2887 | { | |
2888 | ||
2889 | struct mm_struct *mm = current->mm; | |
2890 | struct vm_area_struct *vma; | |
2891 | unsigned long populate = 0; | |
2892 | unsigned long ret = -EINVAL; | |
2893 | struct file *file; | |
2894 | ||
2895 | pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n", | |
2896 | current->comm, current->pid); | |
2897 | ||
2898 | if (prot) | |
2899 | return ret; | |
2900 | start = start & PAGE_MASK; | |
2901 | size = size & PAGE_MASK; | |
2902 | ||
2903 | if (start + size <= start) | |
2904 | return ret; | |
2905 | ||
2906 | /* Does pgoff wrap? */ | |
2907 | if (pgoff + (size >> PAGE_SHIFT) < pgoff) | |
2908 | return ret; | |
2909 | ||
2910 | if (down_write_killable(&mm->mmap_sem)) | |
2911 | return -EINTR; | |
2912 | ||
2913 | vma = find_vma(mm, start); | |
2914 | ||
2915 | if (!vma || !(vma->vm_flags & VM_SHARED)) | |
2916 | goto out; | |
2917 | ||
2918 | if (start < vma->vm_start) | |
2919 | goto out; | |
2920 | ||
2921 | if (start + size > vma->vm_end) { | |
2922 | struct vm_area_struct *next; | |
2923 | ||
2924 | for (next = vma->vm_next; next; next = next->vm_next) { | |
2925 | /* hole between vmas ? */ | |
2926 | if (next->vm_start != next->vm_prev->vm_end) | |
2927 | goto out; | |
2928 | ||
2929 | if (next->vm_file != vma->vm_file) | |
2930 | goto out; | |
2931 | ||
2932 | if (next->vm_flags != vma->vm_flags) | |
2933 | goto out; | |
2934 | ||
2935 | if (start + size <= next->vm_end) | |
2936 | break; | |
2937 | } | |
2938 | ||
2939 | if (!next) | |
2940 | goto out; | |
2941 | } | |
2942 | ||
2943 | prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; | |
2944 | prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; | |
2945 | prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; | |
2946 | ||
2947 | flags &= MAP_NONBLOCK; | |
2948 | flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; | |
2949 | if (vma->vm_flags & VM_LOCKED) { | |
2950 | struct vm_area_struct *tmp; | |
2951 | flags |= MAP_LOCKED; | |
2952 | ||
2953 | /* drop PG_Mlocked flag for over-mapped range */ | |
2954 | for (tmp = vma; tmp->vm_start >= start + size; | |
2955 | tmp = tmp->vm_next) { | |
2956 | /* | |
2957 | * Split pmd and munlock page on the border | |
2958 | * of the range. | |
2959 | */ | |
2960 | vma_adjust_trans_huge(tmp, start, start + size, 0); | |
2961 | ||
2962 | munlock_vma_pages_range(tmp, | |
2963 | max(tmp->vm_start, start), | |
2964 | min(tmp->vm_end, start + size)); | |
2965 | } | |
2966 | } | |
2967 | ||
2968 | file = get_file(vma->vm_file); | |
2969 | ret = do_mmap_pgoff(vma->vm_file, start, size, | |
2970 | prot, flags, pgoff, &populate, NULL); | |
2971 | fput(file); | |
2972 | out: | |
2973 | up_write(&mm->mmap_sem); | |
2974 | if (populate) | |
2975 | mm_populate(ret, populate); | |
2976 | if (!IS_ERR_VALUE(ret)) | |
2977 | ret = 0; | |
2978 | return ret; | |
2979 | } | |
2980 | ||
2981 | /* | |
2982 | * this is really a simplified "do_mmap". it only handles | |
2983 | * anonymous maps. eventually we may be able to do some | |
2984 | * brk-specific accounting here. | |
2985 | */ | |
2986 | static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf) | |
2987 | { | |
2988 | struct mm_struct *mm = current->mm; | |
2989 | struct vm_area_struct *vma, *prev; | |
2990 | struct rb_node **rb_link, *rb_parent; | |
2991 | pgoff_t pgoff = addr >> PAGE_SHIFT; | |
2992 | int error; | |
2993 | ||
2994 | /* Until we need other flags, refuse anything except VM_EXEC. */ | |
2995 | if ((flags & (~VM_EXEC)) != 0) | |
2996 | return -EINVAL; | |
2997 | flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; | |
2998 | ||
2999 | error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); | |
3000 | if (offset_in_page(error)) | |
3001 | return error; | |
3002 | ||
3003 | error = mlock_future_check(mm, mm->def_flags, len); | |
3004 | if (error) | |
3005 | return error; | |
3006 | ||
3007 | /* | |
3008 | * Clear old maps. this also does some error checking for us | |
3009 | */ | |
3010 | while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, | |
3011 | &rb_parent)) { | |
3012 | if (do_munmap(mm, addr, len, uf)) | |
3013 | return -ENOMEM; | |
3014 | } | |
3015 | ||
3016 | /* Check against address space limits *after* clearing old maps... */ | |
3017 | if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) | |
3018 | return -ENOMEM; | |
3019 | ||
3020 | if (mm->map_count > sysctl_max_map_count) | |
3021 | return -ENOMEM; | |
3022 | ||
3023 | if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) | |
3024 | return -ENOMEM; | |
3025 | ||
3026 | /* Can we just expand an old private anonymous mapping? */ | |
3027 | vma = vma_merge(mm, prev, addr, addr + len, flags, | |
3028 | NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX); | |
3029 | if (vma) | |
3030 | goto out; | |
3031 | ||
3032 | /* | |
3033 | * create a vma struct for an anonymous mapping | |
3034 | */ | |
3035 | vma = vm_area_alloc(mm); | |
3036 | if (!vma) { | |
3037 | vm_unacct_memory(len >> PAGE_SHIFT); | |
3038 | return -ENOMEM; | |
3039 | } | |
3040 | ||
3041 | vma_set_anonymous(vma); | |
3042 | vma->vm_start = addr; | |
3043 | vma->vm_end = addr + len; | |
3044 | vma->vm_pgoff = pgoff; | |
3045 | vma->vm_flags = flags; | |
3046 | vma->vm_page_prot = vm_get_page_prot(flags); | |
3047 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
3048 | out: | |
3049 | perf_event_mmap(vma); | |
3050 | mm->total_vm += len >> PAGE_SHIFT; | |
3051 | mm->data_vm += len >> PAGE_SHIFT; | |
3052 | if (flags & VM_LOCKED) | |
3053 | mm->locked_vm += (len >> PAGE_SHIFT); | |
3054 | vma->vm_flags |= VM_SOFTDIRTY; | |
3055 | return 0; | |
3056 | } | |
3057 | ||
3058 | int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) | |
3059 | { | |
3060 | struct mm_struct *mm = current->mm; | |
3061 | unsigned long len; | |
3062 | int ret; | |
3063 | bool populate; | |
3064 | LIST_HEAD(uf); | |
3065 | ||
3066 | len = PAGE_ALIGN(request); | |
3067 | if (len < request) | |
3068 | return -ENOMEM; | |
3069 | if (!len) | |
3070 | return 0; | |
3071 | ||
3072 | if (down_write_killable(&mm->mmap_sem)) | |
3073 | return -EINTR; | |
3074 | ||
3075 | ret = do_brk_flags(addr, len, flags, &uf); | |
3076 | populate = ((mm->def_flags & VM_LOCKED) != 0); | |
3077 | up_write(&mm->mmap_sem); | |
3078 | userfaultfd_unmap_complete(mm, &uf); | |
3079 | if (populate && !ret) | |
3080 | mm_populate(addr, len); | |
3081 | return ret; | |
3082 | } | |
3083 | EXPORT_SYMBOL(vm_brk_flags); | |
3084 | ||
3085 | int vm_brk(unsigned long addr, unsigned long len) | |
3086 | { | |
3087 | return vm_brk_flags(addr, len, 0); | |
3088 | } | |
3089 | EXPORT_SYMBOL(vm_brk); | |
3090 | ||
3091 | /* Release all mmaps. */ | |
3092 | void exit_mmap(struct mm_struct *mm) | |
3093 | { | |
3094 | struct mmu_gather tlb; | |
3095 | struct vm_area_struct *vma; | |
3096 | unsigned long nr_accounted = 0; | |
3097 | ||
3098 | /* mm's last user has gone, and its about to be pulled down */ | |
3099 | mmu_notifier_release(mm); | |
3100 | ||
3101 | if (unlikely(mm_is_oom_victim(mm))) { | |
3102 | /* | |
3103 | * Manually reap the mm to free as much memory as possible. | |
3104 | * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard | |
3105 | * this mm from further consideration. Taking mm->mmap_sem for | |
3106 | * write after setting MMF_OOM_SKIP will guarantee that the oom | |
3107 | * reaper will not run on this mm again after mmap_sem is | |
3108 | * dropped. | |
3109 | * | |
3110 | * Nothing can be holding mm->mmap_sem here and the above call | |
3111 | * to mmu_notifier_release(mm) ensures mmu notifier callbacks in | |
3112 | * __oom_reap_task_mm() will not block. | |
3113 | * | |
3114 | * This needs to be done before calling munlock_vma_pages_all(), | |
3115 | * which clears VM_LOCKED, otherwise the oom reaper cannot | |
3116 | * reliably test it. | |
3117 | */ | |
3118 | (void)__oom_reap_task_mm(mm); | |
3119 | ||
3120 | set_bit(MMF_OOM_SKIP, &mm->flags); | |
3121 | down_write(&mm->mmap_sem); | |
3122 | up_write(&mm->mmap_sem); | |
3123 | } | |
3124 | ||
3125 | if (mm->locked_vm) { | |
3126 | vma = mm->mmap; | |
3127 | while (vma) { | |
3128 | if (vma->vm_flags & VM_LOCKED) | |
3129 | munlock_vma_pages_all(vma); | |
3130 | vma = vma->vm_next; | |
3131 | } | |
3132 | } | |
3133 | ||
3134 | arch_exit_mmap(mm); | |
3135 | ||
3136 | vma = mm->mmap; | |
3137 | if (!vma) /* Can happen if dup_mmap() received an OOM */ | |
3138 | return; | |
3139 | ||
3140 | lru_add_drain(); | |
3141 | flush_cache_mm(mm); | |
3142 | tlb_gather_mmu(&tlb, mm, 0, -1); | |
3143 | /* update_hiwater_rss(mm) here? but nobody should be looking */ | |
3144 | /* Use -1 here to ensure all VMAs in the mm are unmapped */ | |
3145 | unmap_vmas(&tlb, vma, 0, -1); | |
3146 | free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); | |
3147 | tlb_finish_mmu(&tlb, 0, -1); | |
3148 | ||
3149 | /* | |
3150 | * Walk the list again, actually closing and freeing it, | |
3151 | * with preemption enabled, without holding any MM locks. | |
3152 | */ | |
3153 | while (vma) { | |
3154 | if (vma->vm_flags & VM_ACCOUNT) | |
3155 | nr_accounted += vma_pages(vma); | |
3156 | vma = remove_vma(vma); | |
3157 | } | |
3158 | vm_unacct_memory(nr_accounted); | |
3159 | } | |
3160 | ||
3161 | /* Insert vm structure into process list sorted by address | |
3162 | * and into the inode's i_mmap tree. If vm_file is non-NULL | |
3163 | * then i_mmap_rwsem is taken here. | |
3164 | */ | |
3165 | int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) | |
3166 | { | |
3167 | struct vm_area_struct *prev; | |
3168 | struct rb_node **rb_link, *rb_parent; | |
3169 | ||
3170 | if (find_vma_links(mm, vma->vm_start, vma->vm_end, | |
3171 | &prev, &rb_link, &rb_parent)) | |
3172 | return -ENOMEM; | |
3173 | if ((vma->vm_flags & VM_ACCOUNT) && | |
3174 | security_vm_enough_memory_mm(mm, vma_pages(vma))) | |
3175 | return -ENOMEM; | |
3176 | ||
3177 | /* | |
3178 | * The vm_pgoff of a purely anonymous vma should be irrelevant | |
3179 | * until its first write fault, when page's anon_vma and index | |
3180 | * are set. But now set the vm_pgoff it will almost certainly | |
3181 | * end up with (unless mremap moves it elsewhere before that | |
3182 | * first wfault), so /proc/pid/maps tells a consistent story. | |
3183 | * | |
3184 | * By setting it to reflect the virtual start address of the | |
3185 | * vma, merges and splits can happen in a seamless way, just | |
3186 | * using the existing file pgoff checks and manipulations. | |
3187 | * Similarly in do_mmap_pgoff and in do_brk. | |
3188 | */ | |
3189 | if (vma_is_anonymous(vma)) { | |
3190 | BUG_ON(vma->anon_vma); | |
3191 | vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; | |
3192 | } | |
3193 | ||
3194 | vma_link(mm, vma, prev, rb_link, rb_parent); | |
3195 | return 0; | |
3196 | } | |
3197 | ||
3198 | /* | |
3199 | * Copy the vma structure to a new location in the same mm, | |
3200 | * prior to moving page table entries, to effect an mremap move. | |
3201 | */ | |
3202 | struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, | |
3203 | unsigned long addr, unsigned long len, pgoff_t pgoff, | |
3204 | bool *need_rmap_locks) | |
3205 | { | |
3206 | struct vm_area_struct *vma = *vmap; | |
3207 | unsigned long vma_start = vma->vm_start; | |
3208 | struct mm_struct *mm = vma->vm_mm; | |
3209 | struct vm_area_struct *new_vma, *prev; | |
3210 | struct rb_node **rb_link, *rb_parent; | |
3211 | bool faulted_in_anon_vma = true; | |
3212 | ||
3213 | /* | |
3214 | * If anonymous vma has not yet been faulted, update new pgoff | |
3215 | * to match new location, to increase its chance of merging. | |
3216 | */ | |
3217 | if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { | |
3218 | pgoff = addr >> PAGE_SHIFT; | |
3219 | faulted_in_anon_vma = false; | |
3220 | } | |
3221 | ||
3222 | if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) | |
3223 | return NULL; /* should never get here */ | |
3224 | new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, | |
3225 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), | |
3226 | vma->vm_userfaultfd_ctx); | |
3227 | if (new_vma) { | |
3228 | /* | |
3229 | * Source vma may have been merged into new_vma | |
3230 | */ | |
3231 | if (unlikely(vma_start >= new_vma->vm_start && | |
3232 | vma_start < new_vma->vm_end)) { | |
3233 | /* | |
3234 | * The only way we can get a vma_merge with | |
3235 | * self during an mremap is if the vma hasn't | |
3236 | * been faulted in yet and we were allowed to | |
3237 | * reset the dst vma->vm_pgoff to the | |
3238 | * destination address of the mremap to allow | |
3239 | * the merge to happen. mremap must change the | |
3240 | * vm_pgoff linearity between src and dst vmas | |
3241 | * (in turn preventing a vma_merge) to be | |
3242 | * safe. It is only safe to keep the vm_pgoff | |
3243 | * linear if there are no pages mapped yet. | |
3244 | */ | |
3245 | VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); | |
3246 | *vmap = vma = new_vma; | |
3247 | } | |
3248 | *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); | |
3249 | } else { | |
3250 | new_vma = vm_area_dup(vma); | |
3251 | if (!new_vma) | |
3252 | goto out; | |
3253 | new_vma->vm_start = addr; | |
3254 | new_vma->vm_end = addr + len; | |
3255 | new_vma->vm_pgoff = pgoff; | |
3256 | if (vma_dup_policy(vma, new_vma)) | |
3257 | goto out_free_vma; | |
3258 | if (anon_vma_clone(new_vma, vma)) | |
3259 | goto out_free_mempol; | |
3260 | if (new_vma->vm_file) | |
3261 | get_file(new_vma->vm_file); | |
3262 | if (new_vma->vm_ops && new_vma->vm_ops->open) | |
3263 | new_vma->vm_ops->open(new_vma); | |
3264 | vma_link(mm, new_vma, prev, rb_link, rb_parent); | |
3265 | *need_rmap_locks = false; | |
3266 | } | |
3267 | return new_vma; | |
3268 | ||
3269 | out_free_mempol: | |
3270 | mpol_put(vma_policy(new_vma)); | |
3271 | out_free_vma: | |
3272 | vm_area_free(new_vma); | |
3273 | out: | |
3274 | return NULL; | |
3275 | } | |
3276 | ||
3277 | /* | |
3278 | * Return true if the calling process may expand its vm space by the passed | |
3279 | * number of pages | |
3280 | */ | |
3281 | bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) | |
3282 | { | |
3283 | if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) | |
3284 | return false; | |
3285 | ||
3286 | if (is_data_mapping(flags) && | |
3287 | mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { | |
3288 | /* Workaround for Valgrind */ | |
3289 | if (rlimit(RLIMIT_DATA) == 0 && | |
3290 | mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT) | |
3291 | return true; | |
3292 | ||
3293 | pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n", | |
3294 | current->comm, current->pid, | |
3295 | (mm->data_vm + npages) << PAGE_SHIFT, | |
3296 | rlimit(RLIMIT_DATA), | |
3297 | ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data"); | |
3298 | ||
3299 | if (!ignore_rlimit_data) | |
3300 | return false; | |
3301 | } | |
3302 | ||
3303 | return true; | |
3304 | } | |
3305 | ||
3306 | void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) | |
3307 | { | |
3308 | mm->total_vm += npages; | |
3309 | ||
3310 | if (is_exec_mapping(flags)) | |
3311 | mm->exec_vm += npages; | |
3312 | else if (is_stack_mapping(flags)) | |
3313 | mm->stack_vm += npages; | |
3314 | else if (is_data_mapping(flags)) | |
3315 | mm->data_vm += npages; | |
3316 | } | |
3317 | ||
3318 | static vm_fault_t special_mapping_fault(struct vm_fault *vmf); | |
3319 | ||
3320 | /* | |
3321 | * Having a close hook prevents vma merging regardless of flags. | |
3322 | */ | |
3323 | static void special_mapping_close(struct vm_area_struct *vma) | |
3324 | { | |
3325 | } | |
3326 | ||
3327 | static const char *special_mapping_name(struct vm_area_struct *vma) | |
3328 | { | |
3329 | return ((struct vm_special_mapping *)vma->vm_private_data)->name; | |
3330 | } | |
3331 | ||
3332 | static int special_mapping_mremap(struct vm_area_struct *new_vma) | |
3333 | { | |
3334 | struct vm_special_mapping *sm = new_vma->vm_private_data; | |
3335 | ||
3336 | if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) | |
3337 | return -EFAULT; | |
3338 | ||
3339 | if (sm->mremap) | |
3340 | return sm->mremap(sm, new_vma); | |
3341 | ||
3342 | return 0; | |
3343 | } | |
3344 | ||
3345 | static const struct vm_operations_struct special_mapping_vmops = { | |
3346 | .close = special_mapping_close, | |
3347 | .fault = special_mapping_fault, | |
3348 | .mremap = special_mapping_mremap, | |
3349 | .name = special_mapping_name, | |
3350 | }; | |
3351 | ||
3352 | static const struct vm_operations_struct legacy_special_mapping_vmops = { | |
3353 | .close = special_mapping_close, | |
3354 | .fault = special_mapping_fault, | |
3355 | }; | |
3356 | ||
3357 | static vm_fault_t special_mapping_fault(struct vm_fault *vmf) | |
3358 | { | |
3359 | struct vm_area_struct *vma = vmf->vma; | |
3360 | pgoff_t pgoff; | |
3361 | struct page **pages; | |
3362 | ||
3363 | if (vma->vm_ops == &legacy_special_mapping_vmops) { | |
3364 | pages = vma->vm_private_data; | |
3365 | } else { | |
3366 | struct vm_special_mapping *sm = vma->vm_private_data; | |
3367 | ||
3368 | if (sm->fault) | |
3369 | return sm->fault(sm, vmf->vma, vmf); | |
3370 | ||
3371 | pages = sm->pages; | |
3372 | } | |
3373 | ||
3374 | for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) | |
3375 | pgoff--; | |
3376 | ||
3377 | if (*pages) { | |
3378 | struct page *page = *pages; | |
3379 | get_page(page); | |
3380 | vmf->page = page; | |
3381 | return 0; | |
3382 | } | |
3383 | ||
3384 | return VM_FAULT_SIGBUS; | |
3385 | } | |
3386 | ||
3387 | static struct vm_area_struct *__install_special_mapping( | |
3388 | struct mm_struct *mm, | |
3389 | unsigned long addr, unsigned long len, | |
3390 | unsigned long vm_flags, void *priv, | |
3391 | const struct vm_operations_struct *ops) | |
3392 | { | |
3393 | int ret; | |
3394 | struct vm_area_struct *vma; | |
3395 | ||
3396 | vma = vm_area_alloc(mm); | |
3397 | if (unlikely(vma == NULL)) | |
3398 | return ERR_PTR(-ENOMEM); | |
3399 | ||
3400 | vma->vm_start = addr; | |
3401 | vma->vm_end = addr + len; | |
3402 | ||
3403 | vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY; | |
3404 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); | |
3405 | ||
3406 | vma->vm_ops = ops; | |
3407 | vma->vm_private_data = priv; | |
3408 | ||
3409 | ret = insert_vm_struct(mm, vma); | |
3410 | if (ret) | |
3411 | goto out; | |
3412 | ||
3413 | vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); | |
3414 | ||
3415 | perf_event_mmap(vma); | |
3416 | ||
3417 | return vma; | |
3418 | ||
3419 | out: | |
3420 | vm_area_free(vma); | |
3421 | return ERR_PTR(ret); | |
3422 | } | |
3423 | ||
3424 | bool vma_is_special_mapping(const struct vm_area_struct *vma, | |
3425 | const struct vm_special_mapping *sm) | |
3426 | { | |
3427 | return vma->vm_private_data == sm && | |
3428 | (vma->vm_ops == &special_mapping_vmops || | |
3429 | vma->vm_ops == &legacy_special_mapping_vmops); | |
3430 | } | |
3431 | ||
3432 | /* | |
3433 | * Called with mm->mmap_sem held for writing. | |
3434 | * Insert a new vma covering the given region, with the given flags. | |
3435 | * Its pages are supplied by the given array of struct page *. | |
3436 | * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. | |
3437 | * The region past the last page supplied will always produce SIGBUS. | |
3438 | * The array pointer and the pages it points to are assumed to stay alive | |
3439 | * for as long as this mapping might exist. | |
3440 | */ | |
3441 | struct vm_area_struct *_install_special_mapping( | |
3442 | struct mm_struct *mm, | |
3443 | unsigned long addr, unsigned long len, | |
3444 | unsigned long vm_flags, const struct vm_special_mapping *spec) | |
3445 | { | |
3446 | return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, | |
3447 | &special_mapping_vmops); | |
3448 | } | |
3449 | ||
3450 | int install_special_mapping(struct mm_struct *mm, | |
3451 | unsigned long addr, unsigned long len, | |
3452 | unsigned long vm_flags, struct page **pages) | |
3453 | { | |
3454 | struct vm_area_struct *vma = __install_special_mapping( | |
3455 | mm, addr, len, vm_flags, (void *)pages, | |
3456 | &legacy_special_mapping_vmops); | |
3457 | ||
3458 | return PTR_ERR_OR_ZERO(vma); | |
3459 | } | |
3460 | ||
3461 | static DEFINE_MUTEX(mm_all_locks_mutex); | |
3462 | ||
3463 | static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) | |
3464 | { | |
3465 | if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { | |
3466 | /* | |
3467 | * The LSB of head.next can't change from under us | |
3468 | * because we hold the mm_all_locks_mutex. | |
3469 | */ | |
3470 | down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); | |
3471 | /* | |
3472 | * We can safely modify head.next after taking the | |
3473 | * anon_vma->root->rwsem. If some other vma in this mm shares | |
3474 | * the same anon_vma we won't take it again. | |
3475 | * | |
3476 | * No need of atomic instructions here, head.next | |
3477 | * can't change from under us thanks to the | |
3478 | * anon_vma->root->rwsem. | |
3479 | */ | |
3480 | if (__test_and_set_bit(0, (unsigned long *) | |
3481 | &anon_vma->root->rb_root.rb_root.rb_node)) | |
3482 | BUG(); | |
3483 | } | |
3484 | } | |
3485 | ||
3486 | static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) | |
3487 | { | |
3488 | if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { | |
3489 | /* | |
3490 | * AS_MM_ALL_LOCKS can't change from under us because | |
3491 | * we hold the mm_all_locks_mutex. | |
3492 | * | |
3493 | * Operations on ->flags have to be atomic because | |
3494 | * even if AS_MM_ALL_LOCKS is stable thanks to the | |
3495 | * mm_all_locks_mutex, there may be other cpus | |
3496 | * changing other bitflags in parallel to us. | |
3497 | */ | |
3498 | if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) | |
3499 | BUG(); | |
3500 | down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem); | |
3501 | } | |
3502 | } | |
3503 | ||
3504 | /* | |
3505 | * This operation locks against the VM for all pte/vma/mm related | |
3506 | * operations that could ever happen on a certain mm. This includes | |
3507 | * vmtruncate, try_to_unmap, and all page faults. | |
3508 | * | |
3509 | * The caller must take the mmap_sem in write mode before calling | |
3510 | * mm_take_all_locks(). The caller isn't allowed to release the | |
3511 | * mmap_sem until mm_drop_all_locks() returns. | |
3512 | * | |
3513 | * mmap_sem in write mode is required in order to block all operations | |
3514 | * that could modify pagetables and free pages without need of | |
3515 | * altering the vma layout. It's also needed in write mode to avoid new | |
3516 | * anon_vmas to be associated with existing vmas. | |
3517 | * | |
3518 | * A single task can't take more than one mm_take_all_locks() in a row | |
3519 | * or it would deadlock. | |
3520 | * | |
3521 | * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in | |
3522 | * mapping->flags avoid to take the same lock twice, if more than one | |
3523 | * vma in this mm is backed by the same anon_vma or address_space. | |
3524 | * | |
3525 | * We take locks in following order, accordingly to comment at beginning | |
3526 | * of mm/rmap.c: | |
3527 | * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for | |
3528 | * hugetlb mapping); | |
3529 | * - all i_mmap_rwsem locks; | |
3530 | * - all anon_vma->rwseml | |
3531 | * | |
3532 | * We can take all locks within these types randomly because the VM code | |
3533 | * doesn't nest them and we protected from parallel mm_take_all_locks() by | |
3534 | * mm_all_locks_mutex. | |
3535 | * | |
3536 | * mm_take_all_locks() and mm_drop_all_locks are expensive operations | |
3537 | * that may have to take thousand of locks. | |
3538 | * | |
3539 | * mm_take_all_locks() can fail if it's interrupted by signals. | |
3540 | */ | |
3541 | int mm_take_all_locks(struct mm_struct *mm) | |
3542 | { | |
3543 | struct vm_area_struct *vma; | |
3544 | struct anon_vma_chain *avc; | |
3545 | ||
3546 | BUG_ON(down_read_trylock(&mm->mmap_sem)); | |
3547 | ||
3548 | mutex_lock(&mm_all_locks_mutex); | |
3549 | ||
3550 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3551 | if (signal_pending(current)) | |
3552 | goto out_unlock; | |
3553 | if (vma->vm_file && vma->vm_file->f_mapping && | |
3554 | is_vm_hugetlb_page(vma)) | |
3555 | vm_lock_mapping(mm, vma->vm_file->f_mapping); | |
3556 | } | |
3557 | ||
3558 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3559 | if (signal_pending(current)) | |
3560 | goto out_unlock; | |
3561 | if (vma->vm_file && vma->vm_file->f_mapping && | |
3562 | !is_vm_hugetlb_page(vma)) | |
3563 | vm_lock_mapping(mm, vma->vm_file->f_mapping); | |
3564 | } | |
3565 | ||
3566 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3567 | if (signal_pending(current)) | |
3568 | goto out_unlock; | |
3569 | if (vma->anon_vma) | |
3570 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
3571 | vm_lock_anon_vma(mm, avc->anon_vma); | |
3572 | } | |
3573 | ||
3574 | return 0; | |
3575 | ||
3576 | out_unlock: | |
3577 | mm_drop_all_locks(mm); | |
3578 | return -EINTR; | |
3579 | } | |
3580 | ||
3581 | static void vm_unlock_anon_vma(struct anon_vma *anon_vma) | |
3582 | { | |
3583 | if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { | |
3584 | /* | |
3585 | * The LSB of head.next can't change to 0 from under | |
3586 | * us because we hold the mm_all_locks_mutex. | |
3587 | * | |
3588 | * We must however clear the bitflag before unlocking | |
3589 | * the vma so the users using the anon_vma->rb_root will | |
3590 | * never see our bitflag. | |
3591 | * | |
3592 | * No need of atomic instructions here, head.next | |
3593 | * can't change from under us until we release the | |
3594 | * anon_vma->root->rwsem. | |
3595 | */ | |
3596 | if (!__test_and_clear_bit(0, (unsigned long *) | |
3597 | &anon_vma->root->rb_root.rb_root.rb_node)) | |
3598 | BUG(); | |
3599 | anon_vma_unlock_write(anon_vma); | |
3600 | } | |
3601 | } | |
3602 | ||
3603 | static void vm_unlock_mapping(struct address_space *mapping) | |
3604 | { | |
3605 | if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { | |
3606 | /* | |
3607 | * AS_MM_ALL_LOCKS can't change to 0 from under us | |
3608 | * because we hold the mm_all_locks_mutex. | |
3609 | */ | |
3610 | i_mmap_unlock_write(mapping); | |
3611 | if (!test_and_clear_bit(AS_MM_ALL_LOCKS, | |
3612 | &mapping->flags)) | |
3613 | BUG(); | |
3614 | } | |
3615 | } | |
3616 | ||
3617 | /* | |
3618 | * The mmap_sem cannot be released by the caller until | |
3619 | * mm_drop_all_locks() returns. | |
3620 | */ | |
3621 | void mm_drop_all_locks(struct mm_struct *mm) | |
3622 | { | |
3623 | struct vm_area_struct *vma; | |
3624 | struct anon_vma_chain *avc; | |
3625 | ||
3626 | BUG_ON(down_read_trylock(&mm->mmap_sem)); | |
3627 | BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); | |
3628 | ||
3629 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
3630 | if (vma->anon_vma) | |
3631 | list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) | |
3632 | vm_unlock_anon_vma(avc->anon_vma); | |
3633 | if (vma->vm_file && vma->vm_file->f_mapping) | |
3634 | vm_unlock_mapping(vma->vm_file->f_mapping); | |
3635 | } | |
3636 | ||
3637 | mutex_unlock(&mm_all_locks_mutex); | |
3638 | } | |
3639 | ||
3640 | /* | |
3641 | * initialise the percpu counter for VM | |
3642 | */ | |
3643 | void __init mmap_init(void) | |
3644 | { | |
3645 | int ret; | |
3646 | ||
3647 | ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); | |
3648 | VM_BUG_ON(ret); | |
3649 | } | |
3650 | ||
3651 | /* | |
3652 | * Initialise sysctl_user_reserve_kbytes. | |
3653 | * | |
3654 | * This is intended to prevent a user from starting a single memory hogging | |
3655 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER | |
3656 | * mode. | |
3657 | * | |
3658 | * The default value is min(3% of free memory, 128MB) | |
3659 | * 128MB is enough to recover with sshd/login, bash, and top/kill. | |
3660 | */ | |
3661 | static int init_user_reserve(void) | |
3662 | { | |
3663 | unsigned long free_kbytes; | |
3664 | ||
3665 | free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3666 | ||
3667 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); | |
3668 | return 0; | |
3669 | } | |
3670 | subsys_initcall(init_user_reserve); | |
3671 | ||
3672 | /* | |
3673 | * Initialise sysctl_admin_reserve_kbytes. | |
3674 | * | |
3675 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin | |
3676 | * to log in and kill a memory hogging process. | |
3677 | * | |
3678 | * Systems with more than 256MB will reserve 8MB, enough to recover | |
3679 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will | |
3680 | * only reserve 3% of free pages by default. | |
3681 | */ | |
3682 | static int init_admin_reserve(void) | |
3683 | { | |
3684 | unsigned long free_kbytes; | |
3685 | ||
3686 | free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3687 | ||
3688 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); | |
3689 | return 0; | |
3690 | } | |
3691 | subsys_initcall(init_admin_reserve); | |
3692 | ||
3693 | /* | |
3694 | * Reinititalise user and admin reserves if memory is added or removed. | |
3695 | * | |
3696 | * The default user reserve max is 128MB, and the default max for the | |
3697 | * admin reserve is 8MB. These are usually, but not always, enough to | |
3698 | * enable recovery from a memory hogging process using login/sshd, a shell, | |
3699 | * and tools like top. It may make sense to increase or even disable the | |
3700 | * reserve depending on the existence of swap or variations in the recovery | |
3701 | * tools. So, the admin may have changed them. | |
3702 | * | |
3703 | * If memory is added and the reserves have been eliminated or increased above | |
3704 | * the default max, then we'll trust the admin. | |
3705 | * | |
3706 | * If memory is removed and there isn't enough free memory, then we | |
3707 | * need to reset the reserves. | |
3708 | * | |
3709 | * Otherwise keep the reserve set by the admin. | |
3710 | */ | |
3711 | static int reserve_mem_notifier(struct notifier_block *nb, | |
3712 | unsigned long action, void *data) | |
3713 | { | |
3714 | unsigned long tmp, free_kbytes; | |
3715 | ||
3716 | switch (action) { | |
3717 | case MEM_ONLINE: | |
3718 | /* Default max is 128MB. Leave alone if modified by operator. */ | |
3719 | tmp = sysctl_user_reserve_kbytes; | |
3720 | if (0 < tmp && tmp < (1UL << 17)) | |
3721 | init_user_reserve(); | |
3722 | ||
3723 | /* Default max is 8MB. Leave alone if modified by operator. */ | |
3724 | tmp = sysctl_admin_reserve_kbytes; | |
3725 | if (0 < tmp && tmp < (1UL << 13)) | |
3726 | init_admin_reserve(); | |
3727 | ||
3728 | break; | |
3729 | case MEM_OFFLINE: | |
3730 | free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
3731 | ||
3732 | if (sysctl_user_reserve_kbytes > free_kbytes) { | |
3733 | init_user_reserve(); | |
3734 | pr_info("vm.user_reserve_kbytes reset to %lu\n", | |
3735 | sysctl_user_reserve_kbytes); | |
3736 | } | |
3737 | ||
3738 | if (sysctl_admin_reserve_kbytes > free_kbytes) { | |
3739 | init_admin_reserve(); | |
3740 | pr_info("vm.admin_reserve_kbytes reset to %lu\n", | |
3741 | sysctl_admin_reserve_kbytes); | |
3742 | } | |
3743 | break; | |
3744 | default: | |
3745 | break; | |
3746 | } | |
3747 | return NOTIFY_OK; | |
3748 | } | |
3749 | ||
3750 | static struct notifier_block reserve_mem_nb = { | |
3751 | .notifier_call = reserve_mem_notifier, | |
3752 | }; | |
3753 | ||
3754 | static int __meminit init_reserve_notifier(void) | |
3755 | { | |
3756 | if (register_hotmemory_notifier(&reserve_mem_nb)) | |
3757 | pr_err("Failed registering memory add/remove notifier for admin reserve\n"); | |
3758 | ||
3759 | return 0; | |
3760 | } | |
3761 | subsys_initcall(init_reserve_notifier); |