ashmem.c revision 91360b02ab483fc96a70b8c3016838f5d3725f99
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 an ashmem_range 201 * @range: The associated ashmem_range being shrunk 202 * @start: The starting byte of the new range 203 * @end: The ending byte of the new range 204 * 205 * This does not modify the data inside the existing range in any way - It 206 * simply shrinks the boundaries of the range. 207 * 208 * Theoretically, with a little tweaking, this could eventually be changed 209 * to range_resize, and expand the lru_count if the new range is larger. 210 */ 211static inline void range_shrink(struct ashmem_range *range, 212 size_t start, size_t end) 213{ 214 size_t pre = range_size(range); 215 216 range->pgstart = start; 217 range->pgend = end; 218 219 if (range_on_lru(range)) 220 lru_count -= pre - range_size(range); 221} 222 223/** 224 * ashmem_open() - Opens an Anonymous Shared Memory structure 225 * @inode: The backing file's index node(?) 226 * @file: The backing file 227 * 228 * Please note that the ashmem_area is not returned by this function - It is 229 * instead written to "file->private_data". 230 * 231 * Return: 0 if successful, or another code if unsuccessful. 232 */ 233static int ashmem_open(struct inode *inode, struct file *file) 234{ 235 struct ashmem_area *asma; 236 int ret; 237 238 ret = generic_file_open(inode, file); 239 if (unlikely(ret)) 240 return ret; 241 242 asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL); 243 if (unlikely(!asma)) 244 return -ENOMEM; 245 246 INIT_LIST_HEAD(&asma->unpinned_list); 247 memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN); 248 asma->prot_mask = PROT_MASK; 249 file->private_data = asma; 250 251 return 0; 252} 253 254/** 255 * ashmem_release() - Releases an Anonymous Shared Memory structure 256 * @ignored: The backing file's Index Node(?) - It is ignored here. 257 * @file: The backing file 258 * 259 * Return: 0 if successful. If it is anything else, go have a coffee and 260 * try again. 261 */ 262static int ashmem_release(struct inode *ignored, struct file *file) 263{ 264 struct ashmem_area *asma = file->private_data; 265 struct ashmem_range *range, *next; 266 267 mutex_lock(&ashmem_mutex); 268 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) 269 range_del(range); 270 mutex_unlock(&ashmem_mutex); 271 272 if (asma->file) 273 fput(asma->file); 274 kmem_cache_free(ashmem_area_cachep, asma); 275 276 return 0; 277} 278 279/** 280 * ashmem_read() - Reads a set of bytes from an Ashmem-enabled file 281 * @file: The associated backing file. 282 * @buf: The buffer of data being written to 283 * @len: The number of bytes being read 284 * @pos: The position of the first byte to read. 285 * 286 * Return: 0 if successful, or another return code if not. 287 */ 288static ssize_t ashmem_read(struct file *file, char __user *buf, 289 size_t len, loff_t *pos) 290{ 291 struct ashmem_area *asma = file->private_data; 292 int ret = 0; 293 294 mutex_lock(&ashmem_mutex); 295 296 /* If size is not set, or set to 0, always return EOF. */ 297 if (asma->size == 0) 298 goto out_unlock; 299 300 if (!asma->file) { 301 ret = -EBADF; 302 goto out_unlock; 303 } 304 305 mutex_unlock(&ashmem_mutex); 306 307 /* 308 * asma and asma->file are used outside the lock here. We assume 309 * once asma->file is set it will never be changed, and will not 310 * be destroyed until all references to the file are dropped and 311 * ashmem_release is called. 312 */ 313 ret = asma->file->f_op->read(asma->file, buf, len, pos); 314 if (ret >= 0) { 315 /** Update backing file pos, since f_ops->read() doesn't */ 316 asma->file->f_pos = *pos; 317 } 318 return ret; 319 320out_unlock: 321 mutex_unlock(&ashmem_mutex); 322 return ret; 323} 324 325static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin) 326{ 327 struct ashmem_area *asma = file->private_data; 328 int ret; 329 330 mutex_lock(&ashmem_mutex); 331 332 if (asma->size == 0) { 333 ret = -EINVAL; 334 goto out; 335 } 336 337 if (!asma->file) { 338 ret = -EBADF; 339 goto out; 340 } 341 342 ret = vfs_llseek(asma->file, offset, origin); 343 if (ret < 0) 344 goto out; 345 346 /** Copy f_pos from backing file, since f_ops->llseek() sets it */ 347 file->f_pos = asma->file->f_pos; 348 349out: 350 mutex_unlock(&ashmem_mutex); 351 return ret; 352} 353 354static inline vm_flags_t calc_vm_may_flags(unsigned long prot) 355{ 356 return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) | 357 _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) | 358 _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC); 359} 360 361static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) 362{ 363 struct ashmem_area *asma = file->private_data; 364 int ret = 0; 365 366 mutex_lock(&ashmem_mutex); 367 368 /* user needs to SET_SIZE before mapping */ 369 if (unlikely(!asma->size)) { 370 ret = -EINVAL; 371 goto out; 372 } 373 374 /* requested protection bits must match our allowed protection mask */ 375 if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) & 376 calc_vm_prot_bits(PROT_MASK))) { 377 ret = -EPERM; 378 goto out; 379 } 380 vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask); 381 382 if (!asma->file) { 383 char *name = ASHMEM_NAME_DEF; 384 struct file *vmfile; 385 386 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') 387 name = asma->name; 388 389 /* ... and allocate the backing shmem file */ 390 vmfile = shmem_file_setup(name, asma->size, vma->vm_flags); 391 if (unlikely(IS_ERR(vmfile))) { 392 ret = PTR_ERR(vmfile); 393 goto out; 394 } 395 asma->file = vmfile; 396 } 397 get_file(asma->file); 398 399 /* 400 * XXX - Reworked to use shmem_zero_setup() instead of 401 * shmem_set_file while we're in staging. -jstultz 402 */ 403 if (vma->vm_flags & VM_SHARED) { 404 ret = shmem_zero_setup(vma); 405 if (ret) { 406 fput(asma->file); 407 goto out; 408 } 409 } 410 411 if (vma->vm_file) 412 fput(vma->vm_file); 413 vma->vm_file = asma->file; 414 415out: 416 mutex_unlock(&ashmem_mutex); 417 return ret; 418} 419 420/* 421 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab 422 * 423 * 'nr_to_scan' is the number of objects to scan for freeing. 424 * 425 * 'gfp_mask' is the mask of the allocation that got us into this mess. 426 * 427 * Return value is the number of objects freed or -1 if we cannot 428 * proceed without risk of deadlock (due to gfp_mask). 429 * 430 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial 431 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan' 432 * pages freed. 433 */ 434static unsigned long 435ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 436{ 437 struct ashmem_range *range, *next; 438 unsigned long freed = 0; 439 440 /* We might recurse into filesystem code, so bail out if necessary */ 441 if (!(sc->gfp_mask & __GFP_FS)) 442 return SHRINK_STOP; 443 444 mutex_lock(&ashmem_mutex); 445 list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { 446 loff_t start = range->pgstart * PAGE_SIZE; 447 loff_t end = (range->pgend + 1) * PAGE_SIZE; 448 449 do_fallocate(range->asma->file, 450 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 451 start, end - start); 452 range->purged = ASHMEM_WAS_PURGED; 453 lru_del(range); 454 455 freed += range_size(range); 456 if (--sc->nr_to_scan <= 0) 457 break; 458 } 459 mutex_unlock(&ashmem_mutex); 460 return freed; 461} 462 463static unsigned long 464ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc) 465{ 466 /* 467 * note that lru_count is count of pages on the lru, not a count of 468 * objects on the list. This means the scan function needs to return the 469 * number of pages freed, not the number of objects scanned. 470 */ 471 return lru_count; 472} 473 474static struct shrinker ashmem_shrinker = { 475 .count_objects = ashmem_shrink_count, 476 .scan_objects = ashmem_shrink_scan, 477 /* 478 * XXX (dchinner): I wish people would comment on why they need on 479 * significant changes to the default value here 480 */ 481 .seeks = DEFAULT_SEEKS * 4, 482}; 483 484static int set_prot_mask(struct ashmem_area *asma, unsigned long prot) 485{ 486 int ret = 0; 487 488 mutex_lock(&ashmem_mutex); 489 490 /* the user can only remove, not add, protection bits */ 491 if (unlikely((asma->prot_mask & prot) != prot)) { 492 ret = -EINVAL; 493 goto out; 494 } 495 496 /* does the application expect PROT_READ to imply PROT_EXEC? */ 497 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 498 prot |= PROT_EXEC; 499 500 asma->prot_mask = prot; 501 502out: 503 mutex_unlock(&ashmem_mutex); 504 return ret; 505} 506 507static int set_name(struct ashmem_area *asma, void __user *name) 508{ 509 int len; 510 int ret = 0; 511 char local_name[ASHMEM_NAME_LEN]; 512 513 /* 514 * Holding the ashmem_mutex while doing a copy_from_user might cause 515 * an data abort which would try to access mmap_sem. If another 516 * thread has invoked ashmem_mmap then it will be holding the 517 * semaphore and will be waiting for ashmem_mutex, there by leading to 518 * deadlock. We'll release the mutex and take the name to a local 519 * variable that does not need protection and later copy the local 520 * variable to the structure member with lock held. 521 */ 522 len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN); 523 if (len < 0) 524 return len; 525 if (len == ASHMEM_NAME_LEN) 526 local_name[ASHMEM_NAME_LEN - 1] = '\0'; 527 mutex_lock(&ashmem_mutex); 528 /* cannot change an existing mapping's name */ 529 if (unlikely(asma->file)) 530 ret = -EINVAL; 531 else 532 strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name); 533 534 mutex_unlock(&ashmem_mutex); 535 return ret; 536} 537 538static int get_name(struct ashmem_area *asma, void __user *name) 539{ 540 int ret = 0; 541 size_t len; 542 /* 543 * Have a local variable to which we'll copy the content 544 * from asma with the lock held. Later we can copy this to the user 545 * space safely without holding any locks. So even if we proceed to 546 * wait for mmap_sem, it won't lead to deadlock. 547 */ 548 char local_name[ASHMEM_NAME_LEN]; 549 550 mutex_lock(&ashmem_mutex); 551 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') { 552 553 /* 554 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes 555 * prevents us from revealing one user's stack to another. 556 */ 557 len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1; 558 memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len); 559 } else { 560 len = sizeof(ASHMEM_NAME_DEF); 561 memcpy(local_name, ASHMEM_NAME_DEF, len); 562 } 563 mutex_unlock(&ashmem_mutex); 564 565 /* 566 * Now we are just copying from the stack variable to userland 567 * No lock held 568 */ 569 if (unlikely(copy_to_user(name, local_name, len))) 570 ret = -EFAULT; 571 return ret; 572} 573 574/* 575 * ashmem_pin - pin the given ashmem region, returning whether it was 576 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED). 577 * 578 * Caller must hold ashmem_mutex. 579 */ 580static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend) 581{ 582 struct ashmem_range *range, *next; 583 int ret = ASHMEM_NOT_PURGED; 584 585 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { 586 /* moved past last applicable page; we can short circuit */ 587 if (range_before_page(range, pgstart)) 588 break; 589 590 /* 591 * The user can ask us to pin pages that span multiple ranges, 592 * or to pin pages that aren't even unpinned, so this is messy. 593 * 594 * Four cases: 595 * 1. The requested range subsumes an existing range, so we 596 * just remove the entire matching range. 597 * 2. The requested range overlaps the start of an existing 598 * range, so we just update that range. 599 * 3. The requested range overlaps the end of an existing 600 * range, so we just update that range. 601 * 4. The requested range punches a hole in an existing range, 602 * so we have to update one side of the range and then 603 * create a new range for the other side. 604 */ 605 if (page_range_in_range(range, pgstart, pgend)) { 606 ret |= range->purged; 607 608 /* Case #1: Easy. Just nuke the whole thing. */ 609 if (page_range_subsumes_range(range, pgstart, pgend)) { 610 range_del(range); 611 continue; 612 } 613 614 /* Case #2: We overlap from the start, so adjust it */ 615 if (range->pgstart >= pgstart) { 616 range_shrink(range, pgend + 1, range->pgend); 617 continue; 618 } 619 620 /* Case #3: We overlap from the rear, so adjust it */ 621 if (range->pgend <= pgend) { 622 range_shrink(range, range->pgstart, pgstart-1); 623 continue; 624 } 625 626 /* 627 * Case #4: We eat a chunk out of the middle. A bit 628 * more complicated, we allocate a new range for the 629 * second half and adjust the first chunk's endpoint. 630 */ 631 range_alloc(asma, range, range->purged, 632 pgend + 1, range->pgend); 633 range_shrink(range, range->pgstart, pgstart - 1); 634 break; 635 } 636 } 637 638 return ret; 639} 640 641/* 642 * ashmem_unpin - unpin the given range of pages. Returns zero on success. 643 * 644 * Caller must hold ashmem_mutex. 645 */ 646static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend) 647{ 648 struct ashmem_range *range, *next; 649 unsigned int purged = ASHMEM_NOT_PURGED; 650 651restart: 652 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { 653 /* short circuit: this is our insertion point */ 654 if (range_before_page(range, pgstart)) 655 break; 656 657 /* 658 * The user can ask us to unpin pages that are already entirely 659 * or partially pinned. We handle those two cases here. 660 */ 661 if (page_range_subsumed_by_range(range, pgstart, pgend)) 662 return 0; 663 if (page_range_in_range(range, pgstart, pgend)) { 664 pgstart = min_t(size_t, range->pgstart, pgstart), 665 pgend = max_t(size_t, range->pgend, pgend); 666 purged |= range->purged; 667 range_del(range); 668 goto restart; 669 } 670 } 671 672 return range_alloc(asma, range, purged, pgstart, pgend); 673} 674 675/* 676 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the 677 * given interval are unpinned and ASHMEM_IS_PINNED otherwise. 678 * 679 * Caller must hold ashmem_mutex. 680 */ 681static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart, 682 size_t pgend) 683{ 684 struct ashmem_range *range; 685 int ret = ASHMEM_IS_PINNED; 686 687 list_for_each_entry(range, &asma->unpinned_list, unpinned) { 688 if (range_before_page(range, pgstart)) 689 break; 690 if (page_range_in_range(range, pgstart, pgend)) { 691 ret = ASHMEM_IS_UNPINNED; 692 break; 693 } 694 } 695 696 return ret; 697} 698 699static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, 700 void __user *p) 701{ 702 struct ashmem_pin pin; 703 size_t pgstart, pgend; 704 int ret = -EINVAL; 705 706 if (unlikely(!asma->file)) 707 return -EINVAL; 708 709 if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) 710 return -EFAULT; 711 712 /* per custom, you can pass zero for len to mean "everything onward" */ 713 if (!pin.len) 714 pin.len = PAGE_ALIGN(asma->size) - pin.offset; 715 716 if (unlikely((pin.offset | pin.len) & ~PAGE_MASK)) 717 return -EINVAL; 718 719 if (unlikely(((__u32) -1) - pin.offset < pin.len)) 720 return -EINVAL; 721 722 if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len)) 723 return -EINVAL; 724 725 pgstart = pin.offset / PAGE_SIZE; 726 pgend = pgstart + (pin.len / PAGE_SIZE) - 1; 727 728 mutex_lock(&ashmem_mutex); 729 730 switch (cmd) { 731 case ASHMEM_PIN: 732 ret = ashmem_pin(asma, pgstart, pgend); 733 break; 734 case ASHMEM_UNPIN: 735 ret = ashmem_unpin(asma, pgstart, pgend); 736 break; 737 case ASHMEM_GET_PIN_STATUS: 738 ret = ashmem_get_pin_status(asma, pgstart, pgend); 739 break; 740 } 741 742 mutex_unlock(&ashmem_mutex); 743 744 return ret; 745} 746 747static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 748{ 749 struct ashmem_area *asma = file->private_data; 750 long ret = -ENOTTY; 751 752 switch (cmd) { 753 case ASHMEM_SET_NAME: 754 ret = set_name(asma, (void __user *) arg); 755 break; 756 case ASHMEM_GET_NAME: 757 ret = get_name(asma, (void __user *) arg); 758 break; 759 case ASHMEM_SET_SIZE: 760 ret = -EINVAL; 761 if (!asma->file) { 762 ret = 0; 763 asma->size = (size_t) arg; 764 } 765 break; 766 case ASHMEM_GET_SIZE: 767 ret = asma->size; 768 break; 769 case ASHMEM_SET_PROT_MASK: 770 ret = set_prot_mask(asma, arg); 771 break; 772 case ASHMEM_GET_PROT_MASK: 773 ret = asma->prot_mask; 774 break; 775 case ASHMEM_PIN: 776 case ASHMEM_UNPIN: 777 case ASHMEM_GET_PIN_STATUS: 778 ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg); 779 break; 780 case ASHMEM_PURGE_ALL_CACHES: 781 ret = -EPERM; 782 if (capable(CAP_SYS_ADMIN)) { 783 struct shrink_control sc = { 784 .gfp_mask = GFP_KERNEL, 785 .nr_to_scan = LONG_MAX, 786 }; 787 ret = ashmem_shrink_count(&ashmem_shrinker, &sc); 788 nodes_setall(sc.nodes_to_scan); 789 ashmem_shrink_scan(&ashmem_shrinker, &sc); 790 } 791 break; 792 } 793 794 return ret; 795} 796 797/* support of 32bit userspace on 64bit platforms */ 798#ifdef CONFIG_COMPAT 799static long compat_ashmem_ioctl(struct file *file, unsigned int cmd, 800 unsigned long arg) 801{ 802 803 switch (cmd) { 804 case COMPAT_ASHMEM_SET_SIZE: 805 cmd = ASHMEM_SET_SIZE; 806 break; 807 case COMPAT_ASHMEM_SET_PROT_MASK: 808 cmd = ASHMEM_SET_PROT_MASK; 809 break; 810 } 811 return ashmem_ioctl(file, cmd, arg); 812} 813#endif 814 815static const struct file_operations ashmem_fops = { 816 .owner = THIS_MODULE, 817 .open = ashmem_open, 818 .release = ashmem_release, 819 .read = ashmem_read, 820 .llseek = ashmem_llseek, 821 .mmap = ashmem_mmap, 822 .unlocked_ioctl = ashmem_ioctl, 823#ifdef CONFIG_COMPAT 824 .compat_ioctl = compat_ashmem_ioctl, 825#endif 826}; 827 828static struct miscdevice ashmem_misc = { 829 .minor = MISC_DYNAMIC_MINOR, 830 .name = "ashmem", 831 .fops = &ashmem_fops, 832}; 833 834static int __init ashmem_init(void) 835{ 836 int ret; 837 838 ashmem_area_cachep = kmem_cache_create("ashmem_area_cache", 839 sizeof(struct ashmem_area), 840 0, 0, NULL); 841 if (unlikely(!ashmem_area_cachep)) { 842 pr_err("failed to create slab cache\n"); 843 return -ENOMEM; 844 } 845 846 ashmem_range_cachep = kmem_cache_create("ashmem_range_cache", 847 sizeof(struct ashmem_range), 848 0, 0, NULL); 849 if (unlikely(!ashmem_range_cachep)) { 850 pr_err("failed to create slab cache\n"); 851 return -ENOMEM; 852 } 853 854 ret = misc_register(&ashmem_misc); 855 if (unlikely(ret)) { 856 pr_err("failed to register misc device!\n"); 857 return ret; 858 } 859 860 register_shrinker(&ashmem_shrinker); 861 862 pr_info("initialized\n"); 863 864 return 0; 865} 866 867static void __exit ashmem_exit(void) 868{ 869 int ret; 870 871 unregister_shrinker(&ashmem_shrinker); 872 873 ret = misc_deregister(&ashmem_misc); 874 if (unlikely(ret)) 875 pr_err("failed to unregister misc device!\n"); 876 877 kmem_cache_destroy(ashmem_range_cachep); 878 kmem_cache_destroy(ashmem_area_cachep); 879 880 pr_info("unloaded\n"); 881} 882 883module_init(ashmem_init); 884module_exit(ashmem_exit); 885 886MODULE_LICENSE("GPL"); 887