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11980c2a RL |
1 | /* mm/ashmem.c |
2 | ** | |
3 | ** Anonymous Shared Memory Subsystem, ashmem | |
4 | ** | |
5 | ** Copyright (C) 2008 Google, Inc. | |
6 | ** | |
7 | ** Robert Love <rlove@google.com> | |
8 | ** | |
9 | ** This software is licensed under the terms of the GNU General Public | |
10 | ** License version 2, as published by the Free Software Foundation, and | |
11 | ** may be copied, distributed, and modified under those terms. | |
12 | ** | |
13 | ** This program is distributed in the hope that it will be useful, | |
14 | ** but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | ** GNU General Public License for more details. | |
17 | */ | |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/miscdevice.h> | |
23 | #include <linux/security.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/mman.h> | |
26 | #include <linux/uaccess.h> | |
27 | #include <linux/personality.h> | |
28 | #include <linux/bitops.h> | |
29 | #include <linux/mutex.h> | |
30 | #include <linux/shmem_fs.h> | |
31 | #include "ashmem.h" | |
32 | ||
33 | #define ASHMEM_NAME_PREFIX "dev/ashmem/" | |
34 | #define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1) | |
35 | #define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN) | |
36 | ||
37 | /* | |
38 | * ashmem_area - anonymous shared memory area | |
39 | * Lifecycle: From our parent file's open() until its release() | |
40 | * Locking: Protected by `ashmem_mutex' | |
41 | * Big Note: Mappings do NOT pin this structure; it dies on close() | |
42 | */ | |
43 | struct ashmem_area { | |
1efb3439 JS |
44 | char name[ASHMEM_FULL_NAME_LEN]; /* optional name in /proc/pid/maps */ |
45 | struct list_head unpinned_list; /* list of all ashmem areas */ | |
46 | struct file *file; /* the shmem-based backing file */ | |
47 | size_t size; /* size of the mapping, in bytes */ | |
48 | unsigned long prot_mask; /* allowed prot bits, as vm_flags */ | |
11980c2a RL |
49 | }; |
50 | ||
51 | /* | |
52 | * ashmem_range - represents an interval of unpinned (evictable) pages | |
53 | * Lifecycle: From unpin to pin | |
54 | * Locking: Protected by `ashmem_mutex' | |
55 | */ | |
56 | struct ashmem_range { | |
57 | struct list_head lru; /* entry in LRU list */ | |
58 | struct list_head unpinned; /* entry in its area's unpinned list */ | |
59 | struct ashmem_area *asma; /* associated area */ | |
60 | size_t pgstart; /* starting page, inclusive */ | |
61 | size_t pgend; /* ending page, inclusive */ | |
62 | unsigned int purged; /* ASHMEM_NOT or ASHMEM_WAS_PURGED */ | |
63 | }; | |
64 | ||
65 | /* LRU list of unpinned pages, protected by ashmem_mutex */ | |
66 | static LIST_HEAD(ashmem_lru_list); | |
67 | ||
68 | /* Count of pages on our LRU list, protected by ashmem_mutex */ | |
69 | static unsigned long lru_count; | |
70 | ||
71 | /* | |
72 | * ashmem_mutex - protects the list of and each individual ashmem_area | |
73 | * | |
74 | * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem | |
75 | */ | |
76 | static DEFINE_MUTEX(ashmem_mutex); | |
77 | ||
78 | static struct kmem_cache *ashmem_area_cachep __read_mostly; | |
79 | static struct kmem_cache *ashmem_range_cachep __read_mostly; | |
80 | ||
81 | #define range_size(range) \ | |
1efb3439 | 82 | ((range)->pgend - (range)->pgstart + 1) |
11980c2a RL |
83 | |
84 | #define range_on_lru(range) \ | |
1efb3439 | 85 | ((range)->purged == ASHMEM_NOT_PURGED) |
11980c2a RL |
86 | |
87 | #define page_range_subsumes_range(range, start, end) \ | |
1efb3439 | 88 | (((range)->pgstart >= (start)) && ((range)->pgend <= (end))) |
11980c2a RL |
89 | |
90 | #define page_range_subsumed_by_range(range, start, end) \ | |
1efb3439 | 91 | (((range)->pgstart <= (start)) && ((range)->pgend >= (end))) |
11980c2a RL |
92 | |
93 | #define page_in_range(range, page) \ | |
1efb3439 | 94 | (((range)->pgstart <= (page)) && ((range)->pgend >= (page))) |
11980c2a RL |
95 | |
96 | #define page_range_in_range(range, start, end) \ | |
1efb3439 JS |
97 | (page_in_range(range, start) || page_in_range(range, end) || \ |
98 | page_range_subsumes_range(range, start, end)) | |
11980c2a RL |
99 | |
100 | #define range_before_page(range, page) \ | |
1efb3439 | 101 | ((range)->pgend < (page)) |
11980c2a RL |
102 | |
103 | #define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE) | |
104 | ||
105 | static inline void lru_add(struct ashmem_range *range) | |
106 | { | |
107 | list_add_tail(&range->lru, &ashmem_lru_list); | |
108 | lru_count += range_size(range); | |
109 | } | |
110 | ||
111 | static inline void lru_del(struct ashmem_range *range) | |
112 | { | |
113 | list_del(&range->lru); | |
114 | lru_count -= range_size(range); | |
115 | } | |
116 | ||
117 | /* | |
118 | * range_alloc - allocate and initialize a new ashmem_range structure | |
119 | * | |
120 | * 'asma' - associated ashmem_area | |
121 | * 'prev_range' - the previous ashmem_range in the sorted asma->unpinned list | |
122 | * 'purged' - initial purge value (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED) | |
123 | * 'start' - starting page, inclusive | |
124 | * 'end' - ending page, inclusive | |
125 | * | |
126 | * Caller must hold ashmem_mutex. | |
127 | */ | |
128 | static int range_alloc(struct ashmem_area *asma, | |
129 | struct ashmem_range *prev_range, unsigned int purged, | |
130 | size_t start, size_t end) | |
131 | { | |
132 | struct ashmem_range *range; | |
133 | ||
134 | range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL); | |
135 | if (unlikely(!range)) | |
136 | return -ENOMEM; | |
137 | ||
138 | range->asma = asma; | |
139 | range->pgstart = start; | |
140 | range->pgend = end; | |
141 | range->purged = purged; | |
142 | ||
143 | list_add_tail(&range->unpinned, &prev_range->unpinned); | |
144 | ||
145 | if (range_on_lru(range)) | |
146 | lru_add(range); | |
147 | ||
148 | return 0; | |
149 | } | |
150 | ||
151 | static void range_del(struct ashmem_range *range) | |
152 | { | |
153 | list_del(&range->unpinned); | |
154 | if (range_on_lru(range)) | |
155 | lru_del(range); | |
156 | kmem_cache_free(ashmem_range_cachep, range); | |
157 | } | |
158 | ||
159 | /* | |
160 | * range_shrink - shrinks a range | |
161 | * | |
162 | * Caller must hold ashmem_mutex. | |
163 | */ | |
164 | static inline void range_shrink(struct ashmem_range *range, | |
165 | size_t start, size_t end) | |
166 | { | |
167 | size_t pre = range_size(range); | |
168 | ||
169 | range->pgstart = start; | |
170 | range->pgend = end; | |
171 | ||
172 | if (range_on_lru(range)) | |
173 | lru_count -= pre - range_size(range); | |
174 | } | |
175 | ||
176 | static int ashmem_open(struct inode *inode, struct file *file) | |
177 | { | |
178 | struct ashmem_area *asma; | |
179 | int ret; | |
180 | ||
5154b93b | 181 | ret = generic_file_open(inode, file); |
11980c2a RL |
182 | if (unlikely(ret)) |
183 | return ret; | |
184 | ||
185 | asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL); | |
186 | if (unlikely(!asma)) | |
187 | return -ENOMEM; | |
188 | ||
189 | INIT_LIST_HEAD(&asma->unpinned_list); | |
190 | memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN); | |
191 | asma->prot_mask = PROT_MASK; | |
192 | file->private_data = asma; | |
193 | ||
194 | return 0; | |
195 | } | |
196 | ||
197 | static int ashmem_release(struct inode *ignored, struct file *file) | |
198 | { | |
199 | struct ashmem_area *asma = file->private_data; | |
200 | struct ashmem_range *range, *next; | |
201 | ||
202 | mutex_lock(&ashmem_mutex); | |
203 | list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) | |
204 | range_del(range); | |
205 | mutex_unlock(&ashmem_mutex); | |
206 | ||
207 | if (asma->file) | |
208 | fput(asma->file); | |
209 | kmem_cache_free(ashmem_area_cachep, asma); | |
210 | ||
211 | return 0; | |
212 | } | |
213 | ||
853ca7ae BB |
214 | static ssize_t ashmem_read(struct file *file, char __user *buf, |
215 | size_t len, loff_t *pos) | |
216 | { | |
217 | struct ashmem_area *asma = file->private_data; | |
218 | int ret = 0; | |
219 | ||
220 | mutex_lock(&ashmem_mutex); | |
221 | ||
222 | /* If size is not set, or set to 0, always return EOF. */ | |
1efb3439 | 223 | if (asma->size == 0) |
853ca7ae | 224 | goto out; |
853ca7ae BB |
225 | |
226 | if (!asma->file) { | |
227 | ret = -EBADF; | |
228 | goto out; | |
229 | } | |
230 | ||
231 | ret = asma->file->f_op->read(asma->file, buf, len, pos); | |
1efb3439 | 232 | if (ret < 0) |
5154b93b | 233 | goto out; |
5154b93b BB |
234 | |
235 | /** Update backing file pos, since f_ops->read() doesn't */ | |
236 | asma->file->f_pos = *pos; | |
237 | ||
238 | out: | |
239 | mutex_unlock(&ashmem_mutex); | |
240 | return ret; | |
241 | } | |
242 | ||
243 | static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin) | |
244 | { | |
245 | struct ashmem_area *asma = file->private_data; | |
246 | int ret; | |
247 | ||
248 | mutex_lock(&ashmem_mutex); | |
249 | ||
250 | if (asma->size == 0) { | |
251 | ret = -EINVAL; | |
252 | goto out; | |
253 | } | |
254 | ||
255 | if (!asma->file) { | |
256 | ret = -EBADF; | |
257 | goto out; | |
258 | } | |
259 | ||
260 | ret = asma->file->f_op->llseek(asma->file, offset, origin); | |
1efb3439 | 261 | if (ret < 0) |
5154b93b | 262 | goto out; |
5154b93b BB |
263 | |
264 | /** Copy f_pos from backing file, since f_ops->llseek() sets it */ | |
265 | file->f_pos = asma->file->f_pos; | |
853ca7ae BB |
266 | |
267 | out: | |
268 | mutex_unlock(&ashmem_mutex); | |
269 | return ret; | |
270 | } | |
271 | ||
7cfce77d | 272 | static inline vm_flags_t calc_vm_may_flags(unsigned long prot) |
56f76fc6 | 273 | { |
1efb3439 | 274 | return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) | |
56f76fc6 AH |
275 | _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) | |
276 | _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC); | |
277 | } | |
853ca7ae | 278 | |
11980c2a RL |
279 | static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) |
280 | { | |
281 | struct ashmem_area *asma = file->private_data; | |
282 | int ret = 0; | |
283 | ||
284 | mutex_lock(&ashmem_mutex); | |
285 | ||
286 | /* user needs to SET_SIZE before mapping */ | |
287 | if (unlikely(!asma->size)) { | |
288 | ret = -EINVAL; | |
289 | goto out; | |
290 | } | |
291 | ||
292 | /* requested protection bits must match our allowed protection mask */ | |
56f76fc6 | 293 | if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) & |
1efb3439 | 294 | calc_vm_prot_bits(PROT_MASK))) { |
11980c2a RL |
295 | ret = -EPERM; |
296 | goto out; | |
297 | } | |
56f76fc6 | 298 | vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask); |
11980c2a RL |
299 | |
300 | if (!asma->file) { | |
301 | char *name = ASHMEM_NAME_DEF; | |
302 | struct file *vmfile; | |
303 | ||
304 | if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') | |
305 | name = asma->name; | |
306 | ||
307 | /* ... and allocate the backing shmem file */ | |
308 | vmfile = shmem_file_setup(name, asma->size, vma->vm_flags); | |
309 | if (unlikely(IS_ERR(vmfile))) { | |
310 | ret = PTR_ERR(vmfile); | |
311 | goto out; | |
312 | } | |
313 | asma->file = vmfile; | |
314 | } | |
315 | get_file(asma->file); | |
316 | ||
317 | /* | |
aa5af974 | 318 | * XXX - Reworked to use shmem_zero_setup() instead of |
11980c2a RL |
319 | * shmem_set_file while we're in staging. -jstultz |
320 | */ | |
321 | if (vma->vm_flags & VM_SHARED) { | |
322 | ret = shmem_zero_setup(vma); | |
323 | if (ret) { | |
324 | fput(asma->file); | |
325 | goto out; | |
326 | } | |
327 | } | |
328 | ||
329 | if (vma->vm_file) | |
330 | fput(vma->vm_file); | |
331 | vma->vm_file = asma->file; | |
332 | vma->vm_flags |= VM_CAN_NONLINEAR; | |
333 | ||
334 | out: | |
335 | mutex_unlock(&ashmem_mutex); | |
336 | return ret; | |
337 | } | |
338 | ||
339 | /* | |
340 | * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab | |
341 | * | |
342 | * 'nr_to_scan' is the number of objects (pages) to prune, or 0 to query how | |
343 | * many objects (pages) we have in total. | |
344 | * | |
345 | * 'gfp_mask' is the mask of the allocation that got us into this mess. | |
346 | * | |
347 | * Return value is the number of objects (pages) remaining, or -1 if we cannot | |
348 | * proceed without risk of deadlock (due to gfp_mask). | |
349 | * | |
350 | * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial | |
351 | * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan' | |
352 | * pages freed. | |
353 | */ | |
33e8fc46 | 354 | static int ashmem_shrink(struct shrinker *s, struct shrink_control *sc) |
11980c2a RL |
355 | { |
356 | struct ashmem_range *range, *next; | |
357 | ||
358 | /* We might recurse into filesystem code, so bail out if necessary */ | |
33e8fc46 | 359 | if (sc->nr_to_scan && !(sc->gfp_mask & __GFP_FS)) |
11980c2a | 360 | return -1; |
33e8fc46 | 361 | if (!sc->nr_to_scan) |
11980c2a RL |
362 | return lru_count; |
363 | ||
364 | mutex_lock(&ashmem_mutex); | |
365 | list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { | |
366 | struct inode *inode = range->asma->file->f_dentry->d_inode; | |
367 | loff_t start = range->pgstart * PAGE_SIZE; | |
368 | loff_t end = (range->pgend + 1) * PAGE_SIZE - 1; | |
369 | ||
370 | vmtruncate_range(inode, start, end); | |
371 | range->purged = ASHMEM_WAS_PURGED; | |
372 | lru_del(range); | |
373 | ||
33e8fc46 CC |
374 | sc->nr_to_scan -= range_size(range); |
375 | if (sc->nr_to_scan <= 0) | |
11980c2a RL |
376 | break; |
377 | } | |
378 | mutex_unlock(&ashmem_mutex); | |
379 | ||
380 | return lru_count; | |
381 | } | |
382 | ||
383 | static struct shrinker ashmem_shrinker = { | |
384 | .shrink = ashmem_shrink, | |
385 | .seeks = DEFAULT_SEEKS * 4, | |
386 | }; | |
387 | ||
388 | static int set_prot_mask(struct ashmem_area *asma, unsigned long prot) | |
389 | { | |
390 | int ret = 0; | |
391 | ||
392 | mutex_lock(&ashmem_mutex); | |
393 | ||
394 | /* the user can only remove, not add, protection bits */ | |
395 | if (unlikely((asma->prot_mask & prot) != prot)) { | |
396 | ret = -EINVAL; | |
397 | goto out; | |
398 | } | |
399 | ||
400 | /* does the application expect PROT_READ to imply PROT_EXEC? */ | |
401 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) | |
402 | prot |= PROT_EXEC; | |
403 | ||
404 | asma->prot_mask = prot; | |
405 | ||
406 | out: | |
407 | mutex_unlock(&ashmem_mutex); | |
408 | return ret; | |
409 | } | |
410 | ||
411 | static int set_name(struct ashmem_area *asma, void __user *name) | |
412 | { | |
413 | int ret = 0; | |
414 | ||
415 | mutex_lock(&ashmem_mutex); | |
416 | ||
417 | /* cannot change an existing mapping's name */ | |
418 | if (unlikely(asma->file)) { | |
419 | ret = -EINVAL; | |
420 | goto out; | |
421 | } | |
422 | ||
423 | if (unlikely(copy_from_user(asma->name + ASHMEM_NAME_PREFIX_LEN, | |
424 | name, ASHMEM_NAME_LEN))) | |
425 | ret = -EFAULT; | |
426 | asma->name[ASHMEM_FULL_NAME_LEN-1] = '\0'; | |
427 | ||
428 | out: | |
429 | mutex_unlock(&ashmem_mutex); | |
430 | ||
431 | return ret; | |
432 | } | |
433 | ||
434 | static int get_name(struct ashmem_area *asma, void __user *name) | |
435 | { | |
436 | int ret = 0; | |
437 | ||
438 | mutex_lock(&ashmem_mutex); | |
439 | if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') { | |
440 | size_t len; | |
441 | ||
442 | /* | |
443 | * Copying only `len', instead of ASHMEM_NAME_LEN, bytes | |
444 | * prevents us from revealing one user's stack to another. | |
445 | */ | |
446 | len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1; | |
447 | if (unlikely(copy_to_user(name, | |
448 | asma->name + ASHMEM_NAME_PREFIX_LEN, len))) | |
449 | ret = -EFAULT; | |
450 | } else { | |
451 | if (unlikely(copy_to_user(name, ASHMEM_NAME_DEF, | |
452 | sizeof(ASHMEM_NAME_DEF)))) | |
453 | ret = -EFAULT; | |
454 | } | |
455 | mutex_unlock(&ashmem_mutex); | |
456 | ||
457 | return ret; | |
458 | } | |
459 | ||
460 | /* | |
461 | * ashmem_pin - pin the given ashmem region, returning whether it was | |
462 | * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED). | |
463 | * | |
464 | * Caller must hold ashmem_mutex. | |
465 | */ | |
466 | static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend) | |
467 | { | |
468 | struct ashmem_range *range, *next; | |
469 | int ret = ASHMEM_NOT_PURGED; | |
470 | ||
471 | list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { | |
472 | /* moved past last applicable page; we can short circuit */ | |
473 | if (range_before_page(range, pgstart)) | |
474 | break; | |
475 | ||
476 | /* | |
477 | * The user can ask us to pin pages that span multiple ranges, | |
478 | * or to pin pages that aren't even unpinned, so this is messy. | |
479 | * | |
480 | * Four cases: | |
481 | * 1. The requested range subsumes an existing range, so we | |
482 | * just remove the entire matching range. | |
483 | * 2. The requested range overlaps the start of an existing | |
484 | * range, so we just update that range. | |
485 | * 3. The requested range overlaps the end of an existing | |
486 | * range, so we just update that range. | |
487 | * 4. The requested range punches a hole in an existing range, | |
488 | * so we have to update one side of the range and then | |
489 | * create a new range for the other side. | |
490 | */ | |
491 | if (page_range_in_range(range, pgstart, pgend)) { | |
492 | ret |= range->purged; | |
493 | ||
494 | /* Case #1: Easy. Just nuke the whole thing. */ | |
495 | if (page_range_subsumes_range(range, pgstart, pgend)) { | |
496 | range_del(range); | |
497 | continue; | |
498 | } | |
499 | ||
500 | /* Case #2: We overlap from the start, so adjust it */ | |
501 | if (range->pgstart >= pgstart) { | |
502 | range_shrink(range, pgend + 1, range->pgend); | |
503 | continue; | |
504 | } | |
505 | ||
506 | /* Case #3: We overlap from the rear, so adjust it */ | |
507 | if (range->pgend <= pgend) { | |
508 | range_shrink(range, range->pgstart, pgstart-1); | |
509 | continue; | |
510 | } | |
511 | ||
512 | /* | |
513 | * Case #4: We eat a chunk out of the middle. A bit | |
514 | * more complicated, we allocate a new range for the | |
515 | * second half and adjust the first chunk's endpoint. | |
516 | */ | |
517 | range_alloc(asma, range, range->purged, | |
518 | pgend + 1, range->pgend); | |
519 | range_shrink(range, range->pgstart, pgstart - 1); | |
520 | break; | |
521 | } | |
522 | } | |
523 | ||
524 | return ret; | |
525 | } | |
526 | ||
527 | /* | |
528 | * ashmem_unpin - unpin the given range of pages. Returns zero on success. | |
529 | * | |
530 | * Caller must hold ashmem_mutex. | |
531 | */ | |
532 | static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend) | |
533 | { | |
534 | struct ashmem_range *range, *next; | |
535 | unsigned int purged = ASHMEM_NOT_PURGED; | |
536 | ||
537 | restart: | |
538 | list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { | |
539 | /* short circuit: this is our insertion point */ | |
540 | if (range_before_page(range, pgstart)) | |
541 | break; | |
542 | ||
543 | /* | |
544 | * The user can ask us to unpin pages that are already entirely | |
545 | * or partially pinned. We handle those two cases here. | |
546 | */ | |
547 | if (page_range_subsumed_by_range(range, pgstart, pgend)) | |
548 | return 0; | |
549 | if (page_range_in_range(range, pgstart, pgend)) { | |
550 | pgstart = min_t(size_t, range->pgstart, pgstart), | |
551 | pgend = max_t(size_t, range->pgend, pgend); | |
552 | purged |= range->purged; | |
553 | range_del(range); | |
554 | goto restart; | |
555 | } | |
556 | } | |
557 | ||
558 | return range_alloc(asma, range, purged, pgstart, pgend); | |
559 | } | |
560 | ||
561 | /* | |
562 | * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the | |
563 | * given interval are unpinned and ASHMEM_IS_PINNED otherwise. | |
564 | * | |
565 | * Caller must hold ashmem_mutex. | |
566 | */ | |
567 | static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart, | |
568 | size_t pgend) | |
569 | { | |
570 | struct ashmem_range *range; | |
571 | int ret = ASHMEM_IS_PINNED; | |
572 | ||
573 | list_for_each_entry(range, &asma->unpinned_list, unpinned) { | |
574 | if (range_before_page(range, pgstart)) | |
575 | break; | |
576 | if (page_range_in_range(range, pgstart, pgend)) { | |
577 | ret = ASHMEM_IS_UNPINNED; | |
578 | break; | |
579 | } | |
580 | } | |
581 | ||
582 | return ret; | |
583 | } | |
584 | ||
585 | static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, | |
586 | void __user *p) | |
587 | { | |
588 | struct ashmem_pin pin; | |
589 | size_t pgstart, pgend; | |
590 | int ret = -EINVAL; | |
591 | ||
592 | if (unlikely(!asma->file)) | |
593 | return -EINVAL; | |
594 | ||
595 | if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) | |
596 | return -EFAULT; | |
597 | ||
598 | /* per custom, you can pass zero for len to mean "everything onward" */ | |
599 | if (!pin.len) | |
600 | pin.len = PAGE_ALIGN(asma->size) - pin.offset; | |
601 | ||
602 | if (unlikely((pin.offset | pin.len) & ~PAGE_MASK)) | |
603 | return -EINVAL; | |
604 | ||
605 | if (unlikely(((__u32) -1) - pin.offset < pin.len)) | |
606 | return -EINVAL; | |
607 | ||
608 | if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len)) | |
609 | return -EINVAL; | |
610 | ||
611 | pgstart = pin.offset / PAGE_SIZE; | |
612 | pgend = pgstart + (pin.len / PAGE_SIZE) - 1; | |
613 | ||
614 | mutex_lock(&ashmem_mutex); | |
615 | ||
616 | switch (cmd) { | |
617 | case ASHMEM_PIN: | |
618 | ret = ashmem_pin(asma, pgstart, pgend); | |
619 | break; | |
620 | case ASHMEM_UNPIN: | |
621 | ret = ashmem_unpin(asma, pgstart, pgend); | |
622 | break; | |
623 | case ASHMEM_GET_PIN_STATUS: | |
624 | ret = ashmem_get_pin_status(asma, pgstart, pgend); | |
625 | break; | |
626 | } | |
627 | ||
628 | mutex_unlock(&ashmem_mutex); | |
629 | ||
630 | return ret; | |
631 | } | |
632 | ||
633 | static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg) | |
634 | { | |
635 | struct ashmem_area *asma = file->private_data; | |
636 | long ret = -ENOTTY; | |
637 | ||
638 | switch (cmd) { | |
639 | case ASHMEM_SET_NAME: | |
640 | ret = set_name(asma, (void __user *) arg); | |
641 | break; | |
642 | case ASHMEM_GET_NAME: | |
643 | ret = get_name(asma, (void __user *) arg); | |
644 | break; | |
645 | case ASHMEM_SET_SIZE: | |
646 | ret = -EINVAL; | |
647 | if (!asma->file) { | |
648 | ret = 0; | |
649 | asma->size = (size_t) arg; | |
650 | } | |
651 | break; | |
652 | case ASHMEM_GET_SIZE: | |
653 | ret = asma->size; | |
654 | break; | |
655 | case ASHMEM_SET_PROT_MASK: | |
656 | ret = set_prot_mask(asma, arg); | |
657 | break; | |
658 | case ASHMEM_GET_PROT_MASK: | |
659 | ret = asma->prot_mask; | |
660 | break; | |
661 | case ASHMEM_PIN: | |
662 | case ASHMEM_UNPIN: | |
663 | case ASHMEM_GET_PIN_STATUS: | |
664 | ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg); | |
665 | break; | |
666 | case ASHMEM_PURGE_ALL_CACHES: | |
667 | ret = -EPERM; | |
668 | if (capable(CAP_SYS_ADMIN)) { | |
33e8fc46 CC |
669 | struct shrink_control sc = { |
670 | .gfp_mask = GFP_KERNEL, | |
671 | .nr_to_scan = 0, | |
672 | }; | |
673 | ret = ashmem_shrink(&ashmem_shrinker, &sc); | |
674 | sc.nr_to_scan = ret; | |
675 | ashmem_shrink(&ashmem_shrinker, &sc); | |
11980c2a RL |
676 | } |
677 | break; | |
678 | } | |
679 | ||
680 | return ret; | |
681 | } | |
682 | ||
aa5af974 | 683 | static const struct file_operations ashmem_fops = { |
11980c2a RL |
684 | .owner = THIS_MODULE, |
685 | .open = ashmem_open, | |
686 | .release = ashmem_release, | |
1efb3439 JS |
687 | .read = ashmem_read, |
688 | .llseek = ashmem_llseek, | |
11980c2a RL |
689 | .mmap = ashmem_mmap, |
690 | .unlocked_ioctl = ashmem_ioctl, | |
691 | .compat_ioctl = ashmem_ioctl, | |
692 | }; | |
693 | ||
694 | static struct miscdevice ashmem_misc = { | |
695 | .minor = MISC_DYNAMIC_MINOR, | |
696 | .name = "ashmem", | |
697 | .fops = &ashmem_fops, | |
698 | }; | |
699 | ||
700 | static int __init ashmem_init(void) | |
701 | { | |
702 | int ret; | |
703 | ||
704 | ashmem_area_cachep = kmem_cache_create("ashmem_area_cache", | |
705 | sizeof(struct ashmem_area), | |
706 | 0, 0, NULL); | |
707 | if (unlikely(!ashmem_area_cachep)) { | |
708 | printk(KERN_ERR "ashmem: failed to create slab cache\n"); | |
709 | return -ENOMEM; | |
710 | } | |
711 | ||
712 | ashmem_range_cachep = kmem_cache_create("ashmem_range_cache", | |
713 | sizeof(struct ashmem_range), | |
714 | 0, 0, NULL); | |
715 | if (unlikely(!ashmem_range_cachep)) { | |
716 | printk(KERN_ERR "ashmem: failed to create slab cache\n"); | |
717 | return -ENOMEM; | |
718 | } | |
719 | ||
720 | ret = misc_register(&ashmem_misc); | |
721 | if (unlikely(ret)) { | |
722 | printk(KERN_ERR "ashmem: failed to register misc device!\n"); | |
723 | return ret; | |
724 | } | |
725 | ||
726 | register_shrinker(&ashmem_shrinker); | |
727 | ||
728 | printk(KERN_INFO "ashmem: initialized\n"); | |
729 | ||
730 | return 0; | |
731 | } | |
732 | ||
733 | static void __exit ashmem_exit(void) | |
734 | { | |
735 | int ret; | |
736 | ||
737 | unregister_shrinker(&ashmem_shrinker); | |
738 | ||
739 | ret = misc_deregister(&ashmem_misc); | |
740 | if (unlikely(ret)) | |
741 | printk(KERN_ERR "ashmem: failed to unregister misc device!\n"); | |
742 | ||
743 | kmem_cache_destroy(ashmem_range_cachep); | |
744 | kmem_cache_destroy(ashmem_area_cachep); | |
745 | ||
746 | printk(KERN_INFO "ashmem: unloaded\n"); | |
747 | } | |
748 | ||
749 | module_init(ashmem_init); | |
750 | module_exit(ashmem_exit); | |
751 | ||
752 | MODULE_LICENSE("GPL"); |