ashmem.c revision 4d2c9d5ddc3a38abb12253b4fd6ac05bfc3b4462
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#define pr_fmt(fmt) "ashmem: " fmt 20 21#include <linux/module.h> 22#include <linux/file.h> 23#include <linux/fs.h> 24#include <linux/falloc.h> 25#include <linux/miscdevice.h> 26#include <linux/security.h> 27#include <linux/mm.h> 28#include <linux/mman.h> 29#include <linux/uaccess.h> 30#include <linux/personality.h> 31#include <linux/bitops.h> 32#include <linux/mutex.h> 33#include <linux/shmem_fs.h> 34#include "ashmem.h" 35 36#define ASHMEM_NAME_PREFIX "dev/ashmem/" 37#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1) 38#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN) 39 40/** 41 * struct ashmem_area - The anonymous shared memory area 42 * @name: The optional name in /proc/pid/maps 43 * @unpinned_list: The list of all ashmem areas 44 * @file: The shmem-based backing file 45 * @size: The size of the mapping, in bytes 46 * @prot_masks: The allowed protection bits, as vm_flags 47 * 48 * The lifecycle of this structure is from our parent file's open() until 49 * its release(). It is also protected by 'ashmem_mutex' 50 * 51 * Warning: Mappings do NOT pin this structure; It dies on close() 52 */ 53struct ashmem_area { 54 char name[ASHMEM_FULL_NAME_LEN]; 55 struct list_head unpinned_list; 56 struct file *file; 57 size_t size; 58 unsigned long prot_mask; 59}; 60 61/** 62 * struct ashmem_range - A range of unpinned/evictable pages 63 * @lru: The entry in the LRU list 64 * @unpinned: The entry in its area's unpinned list 65 * @asma: The associated anonymous shared memory area. 66 * @pgstart: The starting page (inclusive) 67 * @pgend: The ending page (inclusive) 68 * @purged: The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED) 69 * 70 * The lifecycle of this structure is from unpin to pin. 71 * It is protected by 'ashmem_mutex' 72 */ 73struct ashmem_range { 74 struct list_head lru; 75 struct list_head unpinned; 76 struct ashmem_area *asma; 77 size_t pgstart; 78 size_t pgend; 79 unsigned int purged; 80}; 81 82/* LRU list of unpinned pages, protected by ashmem_mutex */ 83static LIST_HEAD(ashmem_lru_list); 84 85/** 86 * long lru_count - The count of pages on our LRU list. 87 * 88 * This is protected by ashmem_mutex. 89 */ 90static unsigned long lru_count; 91 92/** 93 * ashmem_mutex - protects the list of and each individual ashmem_area 94 * 95 * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem 96 */ 97static DEFINE_MUTEX(ashmem_mutex); 98 99static struct kmem_cache *ashmem_area_cachep __read_mostly; 100static struct kmem_cache *ashmem_range_cachep __read_mostly; 101 102#define range_size(range) \ 103 ((range)->pgend - (range)->pgstart + 1) 104 105#define range_on_lru(range) \ 106 ((range)->purged == ASHMEM_NOT_PURGED) 107 108#define page_range_subsumes_range(range, start, end) \ 109 (((range)->pgstart >= (start)) && ((range)->pgend <= (end))) 110 111#define page_range_subsumed_by_range(range, start, end) \ 112 (((range)->pgstart <= (start)) && ((range)->pgend >= (end))) 113 114#define page_in_range(range, page) \ 115 (((range)->pgstart <= (page)) && ((range)->pgend >= (page))) 116 117#define page_range_in_range(range, start, end) \ 118 (page_in_range(range, start) || page_in_range(range, end) || \ 119 page_range_subsumes_range(range, start, end)) 120 121#define range_before_page(range, page) \ 122 ((range)->pgend < (page)) 123 124#define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE) 125 126/** 127 * lru_add() - Adds a range of memory to the LRU list 128 * @range: The memory range being added. 129 * 130 * The range is first added to the end (tail) of the LRU list. 131 * After this, the size of the range is added to @lru_count 132 */ 133static inline void lru_add(struct ashmem_range *range) 134{ 135 list_add_tail(&range->lru, &ashmem_lru_list); 136 lru_count += range_size(range); 137} 138 139/** 140 * lru_del() - Removes a range of memory from the LRU list 141 * @range: The memory range being removed 142 * 143 * The range is first deleted from the LRU list. 144 * After this, the size of the range is removed from @lru_count 145 */ 146static inline void lru_del(struct ashmem_range *range) 147{ 148 list_del(&range->lru); 149 lru_count -= range_size(range); 150} 151 152/** 153 * range_alloc() - Allocates and initializes a new ashmem_range structure 154 * @asma: The associated ashmem_area 155 * @prev_range: The previous ashmem_range in the sorted asma->unpinned list 156 * @purged: Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED) 157 * @start: The starting page (inclusive) 158 * @end: The ending page (inclusive) 159 * 160 * This function is protected by ashmem_mutex. 161 * 162 * Return: 0 if successful, or -ENOMEM if there is an error 163 */ 164static int range_alloc(struct ashmem_area *asma, 165 struct ashmem_range *prev_range, unsigned int purged, 166 size_t start, size_t end) 167{ 168 struct ashmem_range *range; 169 170 range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL); 171 if (unlikely(!range)) 172 return -ENOMEM; 173 174 range->asma = asma; 175 range->pgstart = start; 176 range->pgend = end; 177 range->purged = purged; 178 179 list_add_tail(&range->unpinned, &prev_range->unpinned); 180 181 if (range_on_lru(range)) 182 lru_add(range); 183 184 return 0; 185} 186 187/** 188 * range_del() - Deletes and dealloctes an ashmem_range structure 189 * @range: The associated ashmem_range that has previously been allocated 190 */ 191static void range_del(struct ashmem_range *range) 192{ 193 list_del(&range->unpinned); 194 if (range_on_lru(range)) 195 lru_del(range); 196 kmem_cache_free(ashmem_range_cachep, range); 197} 198 199/* 200 * range_shrink - shrinks a range 201 * 202 * Caller must hold ashmem_mutex. 203 */ 204static inline void range_shrink(struct ashmem_range *range, 205 size_t start, size_t end) 206{ 207 size_t pre = range_size(range); 208 209 range->pgstart = start; 210 range->pgend = end; 211 212 if (range_on_lru(range)) 213 lru_count -= pre - range_size(range); 214} 215 216static int ashmem_open(struct inode *inode, struct file *file) 217{ 218 struct ashmem_area *asma; 219 int ret; 220 221 ret = generic_file_open(inode, file); 222 if (unlikely(ret)) 223 return ret; 224 225 asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL); 226 if (unlikely(!asma)) 227 return -ENOMEM; 228 229 INIT_LIST_HEAD(&asma->unpinned_list); 230 memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN); 231 asma->prot_mask = PROT_MASK; 232 file->private_data = asma; 233 234 return 0; 235} 236 237static int ashmem_release(struct inode *ignored, struct file *file) 238{ 239 struct ashmem_area *asma = file->private_data; 240 struct ashmem_range *range, *next; 241 242 mutex_lock(&ashmem_mutex); 243 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) 244 range_del(range); 245 mutex_unlock(&ashmem_mutex); 246 247 if (asma->file) 248 fput(asma->file); 249 kmem_cache_free(ashmem_area_cachep, asma); 250 251 return 0; 252} 253 254static ssize_t ashmem_read(struct file *file, char __user *buf, 255 size_t len, loff_t *pos) 256{ 257 struct ashmem_area *asma = file->private_data; 258 int ret = 0; 259 260 mutex_lock(&ashmem_mutex); 261 262 /* If size is not set, or set to 0, always return EOF. */ 263 if (asma->size == 0) 264 goto out; 265 266 if (!asma->file) { 267 ret = -EBADF; 268 goto out; 269 } 270 271 ret = asma->file->f_op->read(asma->file, buf, len, pos); 272 if (ret < 0) 273 goto out; 274 275 /** Update backing file pos, since f_ops->read() doesn't */ 276 asma->file->f_pos = *pos; 277 278out: 279 mutex_unlock(&ashmem_mutex); 280 return ret; 281} 282 283static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin) 284{ 285 struct ashmem_area *asma = file->private_data; 286 int ret; 287 288 mutex_lock(&ashmem_mutex); 289 290 if (asma->size == 0) { 291 ret = -EINVAL; 292 goto out; 293 } 294 295 if (!asma->file) { 296 ret = -EBADF; 297 goto out; 298 } 299 300 ret = asma->file->f_op->llseek(asma->file, offset, origin); 301 if (ret < 0) 302 goto out; 303 304 /** Copy f_pos from backing file, since f_ops->llseek() sets it */ 305 file->f_pos = asma->file->f_pos; 306 307out: 308 mutex_unlock(&ashmem_mutex); 309 return ret; 310} 311 312static inline vm_flags_t calc_vm_may_flags(unsigned long prot) 313{ 314 return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) | 315 _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) | 316 _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC); 317} 318 319static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) 320{ 321 struct ashmem_area *asma = file->private_data; 322 int ret = 0; 323 324 mutex_lock(&ashmem_mutex); 325 326 /* user needs to SET_SIZE before mapping */ 327 if (unlikely(!asma->size)) { 328 ret = -EINVAL; 329 goto out; 330 } 331 332 /* requested protection bits must match our allowed protection mask */ 333 if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) & 334 calc_vm_prot_bits(PROT_MASK))) { 335 ret = -EPERM; 336 goto out; 337 } 338 vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask); 339 340 if (!asma->file) { 341 char *name = ASHMEM_NAME_DEF; 342 struct file *vmfile; 343 344 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') 345 name = asma->name; 346 347 /* ... and allocate the backing shmem file */ 348 vmfile = shmem_file_setup(name, asma->size, vma->vm_flags); 349 if (unlikely(IS_ERR(vmfile))) { 350 ret = PTR_ERR(vmfile); 351 goto out; 352 } 353 asma->file = vmfile; 354 } 355 get_file(asma->file); 356 357 /* 358 * XXX - Reworked to use shmem_zero_setup() instead of 359 * shmem_set_file while we're in staging. -jstultz 360 */ 361 if (vma->vm_flags & VM_SHARED) { 362 ret = shmem_zero_setup(vma); 363 if (ret) { 364 fput(asma->file); 365 goto out; 366 } 367 } 368 369 if (vma->vm_file) 370 fput(vma->vm_file); 371 vma->vm_file = asma->file; 372 373out: 374 mutex_unlock(&ashmem_mutex); 375 return ret; 376} 377 378/* 379 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab 380 * 381 * 'nr_to_scan' is the number of objects to scan for freeing. 382 * 383 * 'gfp_mask' is the mask of the allocation that got us into this mess. 384 * 385 * Return value is the number of objects freed or -1 if we cannot 386 * proceed without risk of deadlock (due to gfp_mask). 387 * 388 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial 389 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan' 390 * pages freed. 391 */ 392static unsigned long 393ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 394{ 395 struct ashmem_range *range, *next; 396 unsigned long freed = 0; 397 398 /* We might recurse into filesystem code, so bail out if necessary */ 399 if (!(sc->gfp_mask & __GFP_FS)) 400 return SHRINK_STOP; 401 402 mutex_lock(&ashmem_mutex); 403 list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { 404 loff_t start = range->pgstart * PAGE_SIZE; 405 loff_t end = (range->pgend + 1) * PAGE_SIZE; 406 407 do_fallocate(range->asma->file, 408 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 409 start, end - start); 410 range->purged = ASHMEM_WAS_PURGED; 411 lru_del(range); 412 413 freed += range_size(range); 414 if (--sc->nr_to_scan <= 0) 415 break; 416 } 417 mutex_unlock(&ashmem_mutex); 418 return freed; 419} 420 421static unsigned long 422ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc) 423{ 424 /* 425 * note that lru_count is count of pages on the lru, not a count of 426 * objects on the list. This means the scan function needs to return the 427 * number of pages freed, not the number of objects scanned. 428 */ 429 return lru_count; 430} 431 432static struct shrinker ashmem_shrinker = { 433 .count_objects = ashmem_shrink_count, 434 .scan_objects = ashmem_shrink_scan, 435 /* 436 * XXX (dchinner): I wish people would comment on why they need on 437 * significant changes to the default value here 438 */ 439 .seeks = DEFAULT_SEEKS * 4, 440}; 441 442static int set_prot_mask(struct ashmem_area *asma, unsigned long prot) 443{ 444 int ret = 0; 445 446 mutex_lock(&ashmem_mutex); 447 448 /* the user can only remove, not add, protection bits */ 449 if (unlikely((asma->prot_mask & prot) != prot)) { 450 ret = -EINVAL; 451 goto out; 452 } 453 454 /* does the application expect PROT_READ to imply PROT_EXEC? */ 455 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 456 prot |= PROT_EXEC; 457 458 asma->prot_mask = prot; 459 460out: 461 mutex_unlock(&ashmem_mutex); 462 return ret; 463} 464 465static int set_name(struct ashmem_area *asma, void __user *name) 466{ 467 int ret = 0; 468 char local_name[ASHMEM_NAME_LEN]; 469 470 /* 471 * Holding the ashmem_mutex while doing a copy_from_user might cause 472 * an data abort which would try to access mmap_sem. If another 473 * thread has invoked ashmem_mmap then it will be holding the 474 * semaphore and will be waiting for ashmem_mutex, there by leading to 475 * deadlock. We'll release the mutex and take the name to a local 476 * variable that does not need protection and later copy the local 477 * variable to the structure member with lock held. 478 */ 479 if (copy_from_user(local_name, name, ASHMEM_NAME_LEN)) 480 return -EFAULT; 481 482 mutex_lock(&ashmem_mutex); 483 /* cannot change an existing mapping's name */ 484 if (unlikely(asma->file)) { 485 ret = -EINVAL; 486 goto out; 487 } 488 memcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, 489 local_name, ASHMEM_NAME_LEN); 490 asma->name[ASHMEM_FULL_NAME_LEN-1] = '\0'; 491out: 492 mutex_unlock(&ashmem_mutex); 493 494 return ret; 495} 496 497static int get_name(struct ashmem_area *asma, void __user *name) 498{ 499 int ret = 0; 500 size_t len; 501 /* 502 * Have a local variable to which we'll copy the content 503 * from asma with the lock held. Later we can copy this to the user 504 * space safely without holding any locks. So even if we proceed to 505 * wait for mmap_sem, it won't lead to deadlock. 506 */ 507 char local_name[ASHMEM_NAME_LEN]; 508 509 mutex_lock(&ashmem_mutex); 510 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') { 511 512 /* 513 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes 514 * prevents us from revealing one user's stack to another. 515 */ 516 len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1; 517 memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len); 518 } else { 519 len = sizeof(ASHMEM_NAME_DEF); 520 memcpy(local_name, ASHMEM_NAME_DEF, len); 521 } 522 mutex_unlock(&ashmem_mutex); 523 524 /* 525 * Now we are just copying from the stack variable to userland 526 * No lock held 527 */ 528 if (unlikely(copy_to_user(name, local_name, len))) 529 ret = -EFAULT; 530 return ret; 531} 532 533/* 534 * ashmem_pin - pin the given ashmem region, returning whether it was 535 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED). 536 * 537 * Caller must hold ashmem_mutex. 538 */ 539static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend) 540{ 541 struct ashmem_range *range, *next; 542 int ret = ASHMEM_NOT_PURGED; 543 544 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { 545 /* moved past last applicable page; we can short circuit */ 546 if (range_before_page(range, pgstart)) 547 break; 548 549 /* 550 * The user can ask us to pin pages that span multiple ranges, 551 * or to pin pages that aren't even unpinned, so this is messy. 552 * 553 * Four cases: 554 * 1. The requested range subsumes an existing range, so we 555 * just remove the entire matching range. 556 * 2. The requested range overlaps the start of an existing 557 * range, so we just update that range. 558 * 3. The requested range overlaps the end of an existing 559 * range, so we just update that range. 560 * 4. The requested range punches a hole in an existing range, 561 * so we have to update one side of the range and then 562 * create a new range for the other side. 563 */ 564 if (page_range_in_range(range, pgstart, pgend)) { 565 ret |= range->purged; 566 567 /* Case #1: Easy. Just nuke the whole thing. */ 568 if (page_range_subsumes_range(range, pgstart, pgend)) { 569 range_del(range); 570 continue; 571 } 572 573 /* Case #2: We overlap from the start, so adjust it */ 574 if (range->pgstart >= pgstart) { 575 range_shrink(range, pgend + 1, range->pgend); 576 continue; 577 } 578 579 /* Case #3: We overlap from the rear, so adjust it */ 580 if (range->pgend <= pgend) { 581 range_shrink(range, range->pgstart, pgstart-1); 582 continue; 583 } 584 585 /* 586 * Case #4: We eat a chunk out of the middle. A bit 587 * more complicated, we allocate a new range for the 588 * second half and adjust the first chunk's endpoint. 589 */ 590 range_alloc(asma, range, range->purged, 591 pgend + 1, range->pgend); 592 range_shrink(range, range->pgstart, pgstart - 1); 593 break; 594 } 595 } 596 597 return ret; 598} 599 600/* 601 * ashmem_unpin - unpin the given range of pages. Returns zero on success. 602 * 603 * Caller must hold ashmem_mutex. 604 */ 605static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend) 606{ 607 struct ashmem_range *range, *next; 608 unsigned int purged = ASHMEM_NOT_PURGED; 609 610restart: 611 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { 612 /* short circuit: this is our insertion point */ 613 if (range_before_page(range, pgstart)) 614 break; 615 616 /* 617 * The user can ask us to unpin pages that are already entirely 618 * or partially pinned. We handle those two cases here. 619 */ 620 if (page_range_subsumed_by_range(range, pgstart, pgend)) 621 return 0; 622 if (page_range_in_range(range, pgstart, pgend)) { 623 pgstart = min_t(size_t, range->pgstart, pgstart), 624 pgend = max_t(size_t, range->pgend, pgend); 625 purged |= range->purged; 626 range_del(range); 627 goto restart; 628 } 629 } 630 631 return range_alloc(asma, range, purged, pgstart, pgend); 632} 633 634/* 635 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the 636 * given interval are unpinned and ASHMEM_IS_PINNED otherwise. 637 * 638 * Caller must hold ashmem_mutex. 639 */ 640static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart, 641 size_t pgend) 642{ 643 struct ashmem_range *range; 644 int ret = ASHMEM_IS_PINNED; 645 646 list_for_each_entry(range, &asma->unpinned_list, unpinned) { 647 if (range_before_page(range, pgstart)) 648 break; 649 if (page_range_in_range(range, pgstart, pgend)) { 650 ret = ASHMEM_IS_UNPINNED; 651 break; 652 } 653 } 654 655 return ret; 656} 657 658static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, 659 void __user *p) 660{ 661 struct ashmem_pin pin; 662 size_t pgstart, pgend; 663 int ret = -EINVAL; 664 665 if (unlikely(!asma->file)) 666 return -EINVAL; 667 668 if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) 669 return -EFAULT; 670 671 /* per custom, you can pass zero for len to mean "everything onward" */ 672 if (!pin.len) 673 pin.len = PAGE_ALIGN(asma->size) - pin.offset; 674 675 if (unlikely((pin.offset | pin.len) & ~PAGE_MASK)) 676 return -EINVAL; 677 678 if (unlikely(((__u32) -1) - pin.offset < pin.len)) 679 return -EINVAL; 680 681 if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len)) 682 return -EINVAL; 683 684 pgstart = pin.offset / PAGE_SIZE; 685 pgend = pgstart + (pin.len / PAGE_SIZE) - 1; 686 687 mutex_lock(&ashmem_mutex); 688 689 switch (cmd) { 690 case ASHMEM_PIN: 691 ret = ashmem_pin(asma, pgstart, pgend); 692 break; 693 case ASHMEM_UNPIN: 694 ret = ashmem_unpin(asma, pgstart, pgend); 695 break; 696 case ASHMEM_GET_PIN_STATUS: 697 ret = ashmem_get_pin_status(asma, pgstart, pgend); 698 break; 699 } 700 701 mutex_unlock(&ashmem_mutex); 702 703 return ret; 704} 705 706static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 707{ 708 struct ashmem_area *asma = file->private_data; 709 long ret = -ENOTTY; 710 711 switch (cmd) { 712 case ASHMEM_SET_NAME: 713 ret = set_name(asma, (void __user *) arg); 714 break; 715 case ASHMEM_GET_NAME: 716 ret = get_name(asma, (void __user *) arg); 717 break; 718 case ASHMEM_SET_SIZE: 719 ret = -EINVAL; 720 if (!asma->file) { 721 ret = 0; 722 asma->size = (size_t) arg; 723 } 724 break; 725 case ASHMEM_GET_SIZE: 726 ret = asma->size; 727 break; 728 case ASHMEM_SET_PROT_MASK: 729 ret = set_prot_mask(asma, arg); 730 break; 731 case ASHMEM_GET_PROT_MASK: 732 ret = asma->prot_mask; 733 break; 734 case ASHMEM_PIN: 735 case ASHMEM_UNPIN: 736 case ASHMEM_GET_PIN_STATUS: 737 ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg); 738 break; 739 case ASHMEM_PURGE_ALL_CACHES: 740 ret = -EPERM; 741 if (capable(CAP_SYS_ADMIN)) { 742 struct shrink_control sc = { 743 .gfp_mask = GFP_KERNEL, 744 .nr_to_scan = LONG_MAX, 745 }; 746 747 nodes_setall(sc.nodes_to_scan); 748 ashmem_shrink_scan(&ashmem_shrinker, &sc); 749 } 750 break; 751 } 752 753 return ret; 754} 755 756/* support of 32bit userspace on 64bit platforms */ 757#ifdef CONFIG_COMPAT 758static long compat_ashmem_ioctl(struct file *file, unsigned int cmd, 759 unsigned long arg) 760{ 761 762 switch (cmd) { 763 case COMPAT_ASHMEM_SET_SIZE: 764 cmd = ASHMEM_SET_SIZE; 765 break; 766 case COMPAT_ASHMEM_SET_PROT_MASK: 767 cmd = ASHMEM_SET_PROT_MASK; 768 break; 769 } 770 return ashmem_ioctl(file, cmd, arg); 771} 772#endif 773 774static const struct file_operations ashmem_fops = { 775 .owner = THIS_MODULE, 776 .open = ashmem_open, 777 .release = ashmem_release, 778 .read = ashmem_read, 779 .llseek = ashmem_llseek, 780 .mmap = ashmem_mmap, 781 .unlocked_ioctl = ashmem_ioctl, 782#ifdef CONFIG_COMPAT 783 .compat_ioctl = compat_ashmem_ioctl, 784#endif 785}; 786 787static struct miscdevice ashmem_misc = { 788 .minor = MISC_DYNAMIC_MINOR, 789 .name = "ashmem", 790 .fops = &ashmem_fops, 791}; 792 793static int __init ashmem_init(void) 794{ 795 int ret; 796 797 ashmem_area_cachep = kmem_cache_create("ashmem_area_cache", 798 sizeof(struct ashmem_area), 799 0, 0, NULL); 800 if (unlikely(!ashmem_area_cachep)) { 801 pr_err("failed to create slab cache\n"); 802 return -ENOMEM; 803 } 804 805 ashmem_range_cachep = kmem_cache_create("ashmem_range_cache", 806 sizeof(struct ashmem_range), 807 0, 0, NULL); 808 if (unlikely(!ashmem_range_cachep)) { 809 pr_err("failed to create slab cache\n"); 810 return -ENOMEM; 811 } 812 813 ret = misc_register(&ashmem_misc); 814 if (unlikely(ret)) { 815 pr_err("failed to register misc device!\n"); 816 return ret; 817 } 818 819 register_shrinker(&ashmem_shrinker); 820 821 pr_info("initialized\n"); 822 823 return 0; 824} 825 826static void __exit ashmem_exit(void) 827{ 828 int ret; 829 830 unregister_shrinker(&ashmem_shrinker); 831 832 ret = misc_deregister(&ashmem_misc); 833 if (unlikely(ret)) 834 pr_err("failed to unregister misc device!\n"); 835 836 kmem_cache_destroy(ashmem_range_cachep); 837 kmem_cache_destroy(ashmem_area_cachep); 838 839 pr_info("unloaded\n"); 840} 841 842module_init(ashmem_init); 843module_exit(ashmem_exit); 844 845MODULE_LICENSE("GPL"); 846