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 if (vma->vm_flags & VM_SHARED) 400 shmem_set_file(vma, asma->file); 401 else { 402 if (vma->vm_file) 403 fput(vma->vm_file); 404 vma->vm_file = asma->file; 405 } 406 407out: 408 mutex_unlock(&ashmem_mutex); 409 return ret; 410} 411 412/* 413 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab 414 * 415 * 'nr_to_scan' is the number of objects to scan for freeing. 416 * 417 * 'gfp_mask' is the mask of the allocation that got us into this mess. 418 * 419 * Return value is the number of objects freed or -1 if we cannot 420 * proceed without risk of deadlock (due to gfp_mask). 421 * 422 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial 423 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan' 424 * pages freed. 425 */ 426static unsigned long 427ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 428{ 429 struct ashmem_range *range, *next; 430 unsigned long freed = 0; 431 432 /* We might recurse into filesystem code, so bail out if necessary */ 433 if (!(sc->gfp_mask & __GFP_FS)) 434 return SHRINK_STOP; 435 436 if (!mutex_trylock(&ashmem_mutex)) 437 return -1; 438 439 list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { 440 loff_t start = range->pgstart * PAGE_SIZE; 441 loff_t end = (range->pgend + 1) * PAGE_SIZE; 442 443 range->asma->file->f_op->fallocate(range->asma->file, 444 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 445 start, end - start); 446 range->purged = ASHMEM_WAS_PURGED; 447 lru_del(range); 448 449 freed += range_size(range); 450 if (--sc->nr_to_scan <= 0) 451 break; 452 } 453 mutex_unlock(&ashmem_mutex); 454 return freed; 455} 456 457static unsigned long 458ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc) 459{ 460 /* 461 * note that lru_count is count of pages on the lru, not a count of 462 * objects on the list. This means the scan function needs to return the 463 * number of pages freed, not the number of objects scanned. 464 */ 465 return lru_count; 466} 467 468static struct shrinker ashmem_shrinker = { 469 .count_objects = ashmem_shrink_count, 470 .scan_objects = ashmem_shrink_scan, 471 /* 472 * XXX (dchinner): I wish people would comment on why they need on 473 * significant changes to the default value here 474 */ 475 .seeks = DEFAULT_SEEKS * 4, 476}; 477 478static int set_prot_mask(struct ashmem_area *asma, unsigned long prot) 479{ 480 int ret = 0; 481 482 mutex_lock(&ashmem_mutex); 483 484 /* the user can only remove, not add, protection bits */ 485 if (unlikely((asma->prot_mask & prot) != prot)) { 486 ret = -EINVAL; 487 goto out; 488 } 489 490 /* does the application expect PROT_READ to imply PROT_EXEC? */ 491 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 492 prot |= PROT_EXEC; 493 494 asma->prot_mask = prot; 495 496out: 497 mutex_unlock(&ashmem_mutex); 498 return ret; 499} 500 501static int set_name(struct ashmem_area *asma, void __user *name) 502{ 503 int len; 504 int ret = 0; 505 char local_name[ASHMEM_NAME_LEN]; 506 507 /* 508 * Holding the ashmem_mutex while doing a copy_from_user might cause 509 * an data abort which would try to access mmap_sem. If another 510 * thread has invoked ashmem_mmap then it will be holding the 511 * semaphore and will be waiting for ashmem_mutex, there by leading to 512 * deadlock. We'll release the mutex and take the name to a local 513 * variable that does not need protection and later copy the local 514 * variable to the structure member with lock held. 515 */ 516 len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN); 517 if (len < 0) 518 return len; 519 if (len == ASHMEM_NAME_LEN) 520 local_name[ASHMEM_NAME_LEN - 1] = '\0'; 521 mutex_lock(&ashmem_mutex); 522 /* cannot change an existing mapping's name */ 523 if (unlikely(asma->file)) 524 ret = -EINVAL; 525 else 526 strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name); 527 528 mutex_unlock(&ashmem_mutex); 529 return ret; 530} 531 532static int get_name(struct ashmem_area *asma, void __user *name) 533{ 534 int ret = 0; 535 size_t len; 536 /* 537 * Have a local variable to which we'll copy the content 538 * from asma with the lock held. Later we can copy this to the user 539 * space safely without holding any locks. So even if we proceed to 540 * wait for mmap_sem, it won't lead to deadlock. 541 */ 542 char local_name[ASHMEM_NAME_LEN]; 543 544 mutex_lock(&ashmem_mutex); 545 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') { 546 547 /* 548 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes 549 * prevents us from revealing one user's stack to another. 550 */ 551 len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1; 552 memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len); 553 } else { 554 len = sizeof(ASHMEM_NAME_DEF); 555 memcpy(local_name, ASHMEM_NAME_DEF, len); 556 } 557 mutex_unlock(&ashmem_mutex); 558 559 /* 560 * Now we are just copying from the stack variable to userland 561 * No lock held 562 */ 563 if (unlikely(copy_to_user(name, local_name, len))) 564 ret = -EFAULT; 565 return ret; 566} 567 568/* 569 * ashmem_pin - pin the given ashmem region, returning whether it was 570 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED). 571 * 572 * Caller must hold ashmem_mutex. 573 */ 574static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend) 575{ 576 struct ashmem_range *range, *next; 577 int ret = ASHMEM_NOT_PURGED; 578 579 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { 580 /* moved past last applicable page; we can short circuit */ 581 if (range_before_page(range, pgstart)) 582 break; 583 584 /* 585 * The user can ask us to pin pages that span multiple ranges, 586 * or to pin pages that aren't even unpinned, so this is messy. 587 * 588 * Four cases: 589 * 1. The requested range subsumes an existing range, so we 590 * just remove the entire matching range. 591 * 2. The requested range overlaps the start of an existing 592 * range, so we just update that range. 593 * 3. The requested range overlaps the end of an existing 594 * range, so we just update that range. 595 * 4. The requested range punches a hole in an existing range, 596 * so we have to update one side of the range and then 597 * create a new range for the other side. 598 */ 599 if (page_range_in_range(range, pgstart, pgend)) { 600 ret |= range->purged; 601 602 /* Case #1: Easy. Just nuke the whole thing. */ 603 if (page_range_subsumes_range(range, pgstart, pgend)) { 604 range_del(range); 605 continue; 606 } 607 608 /* Case #2: We overlap from the start, so adjust it */ 609 if (range->pgstart >= pgstart) { 610 range_shrink(range, pgend + 1, range->pgend); 611 continue; 612 } 613 614 /* Case #3: We overlap from the rear, so adjust it */ 615 if (range->pgend <= pgend) { 616 range_shrink(range, range->pgstart, pgstart-1); 617 continue; 618 } 619 620 /* 621 * Case #4: We eat a chunk out of the middle. A bit 622 * more complicated, we allocate a new range for the 623 * second half and adjust the first chunk's endpoint. 624 */ 625 range_alloc(asma, range, range->purged, 626 pgend + 1, range->pgend); 627 range_shrink(range, range->pgstart, pgstart - 1); 628 break; 629 } 630 } 631 632 return ret; 633} 634 635/* 636 * ashmem_unpin - unpin the given range of pages. Returns zero on success. 637 * 638 * Caller must hold ashmem_mutex. 639 */ 640static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend) 641{ 642 struct ashmem_range *range, *next; 643 unsigned int purged = ASHMEM_NOT_PURGED; 644 645restart: 646 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) { 647 /* short circuit: this is our insertion point */ 648 if (range_before_page(range, pgstart)) 649 break; 650 651 /* 652 * The user can ask us to unpin pages that are already entirely 653 * or partially pinned. We handle those two cases here. 654 */ 655 if (page_range_subsumed_by_range(range, pgstart, pgend)) 656 return 0; 657 if (page_range_in_range(range, pgstart, pgend)) { 658 pgstart = min_t(size_t, range->pgstart, pgstart), 659 pgend = max_t(size_t, range->pgend, pgend); 660 purged |= range->purged; 661 range_del(range); 662 goto restart; 663 } 664 } 665 666 return range_alloc(asma, range, purged, pgstart, pgend); 667} 668 669/* 670 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the 671 * given interval are unpinned and ASHMEM_IS_PINNED otherwise. 672 * 673 * Caller must hold ashmem_mutex. 674 */ 675static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart, 676 size_t pgend) 677{ 678 struct ashmem_range *range; 679 int ret = ASHMEM_IS_PINNED; 680 681 list_for_each_entry(range, &asma->unpinned_list, unpinned) { 682 if (range_before_page(range, pgstart)) 683 break; 684 if (page_range_in_range(range, pgstart, pgend)) { 685 ret = ASHMEM_IS_UNPINNED; 686 break; 687 } 688 } 689 690 return ret; 691} 692 693static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd, 694 void __user *p) 695{ 696 struct ashmem_pin pin; 697 size_t pgstart, pgend; 698 int ret = -EINVAL; 699 700 if (unlikely(!asma->file)) 701 return -EINVAL; 702 703 if (unlikely(copy_from_user(&pin, p, sizeof(pin)))) 704 return -EFAULT; 705 706 /* per custom, you can pass zero for len to mean "everything onward" */ 707 if (!pin.len) 708 pin.len = PAGE_ALIGN(asma->size) - pin.offset; 709 710 if (unlikely((pin.offset | pin.len) & ~PAGE_MASK)) 711 return -EINVAL; 712 713 if (unlikely(((__u32) -1) - pin.offset < pin.len)) 714 return -EINVAL; 715 716 if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len)) 717 return -EINVAL; 718 719 pgstart = pin.offset / PAGE_SIZE; 720 pgend = pgstart + (pin.len / PAGE_SIZE) - 1; 721 722 mutex_lock(&ashmem_mutex); 723 724 switch (cmd) { 725 case ASHMEM_PIN: 726 ret = ashmem_pin(asma, pgstart, pgend); 727 break; 728 case ASHMEM_UNPIN: 729 ret = ashmem_unpin(asma, pgstart, pgend); 730 break; 731 case ASHMEM_GET_PIN_STATUS: 732 ret = ashmem_get_pin_status(asma, pgstart, pgend); 733 break; 734 } 735 736 mutex_unlock(&ashmem_mutex); 737 738 return ret; 739} 740 741static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 742{ 743 struct ashmem_area *asma = file->private_data; 744 long ret = -ENOTTY; 745 746 switch (cmd) { 747 case ASHMEM_SET_NAME: 748 ret = set_name(asma, (void __user *) arg); 749 break; 750 case ASHMEM_GET_NAME: 751 ret = get_name(asma, (void __user *) arg); 752 break; 753 case ASHMEM_SET_SIZE: 754 ret = -EINVAL; 755 if (!asma->file) { 756 ret = 0; 757 asma->size = (size_t) arg; 758 } 759 break; 760 case ASHMEM_GET_SIZE: 761 ret = asma->size; 762 break; 763 case ASHMEM_SET_PROT_MASK: 764 ret = set_prot_mask(asma, arg); 765 break; 766 case ASHMEM_GET_PROT_MASK: 767 ret = asma->prot_mask; 768 break; 769 case ASHMEM_PIN: 770 case ASHMEM_UNPIN: 771 case ASHMEM_GET_PIN_STATUS: 772 ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg); 773 break; 774 case ASHMEM_PURGE_ALL_CACHES: 775 ret = -EPERM; 776 if (capable(CAP_SYS_ADMIN)) { 777 struct shrink_control sc = { 778 .gfp_mask = GFP_KERNEL, 779 .nr_to_scan = LONG_MAX, 780 }; 781 ret = ashmem_shrink_count(&ashmem_shrinker, &sc); 782 nodes_setall(sc.nodes_to_scan); 783 ashmem_shrink_scan(&ashmem_shrinker, &sc); 784 } 785 break; 786 } 787 788 return ret; 789} 790 791/* support of 32bit userspace on 64bit platforms */ 792#ifdef CONFIG_COMPAT 793static long compat_ashmem_ioctl(struct file *file, unsigned int cmd, 794 unsigned long arg) 795{ 796 797 switch (cmd) { 798 case COMPAT_ASHMEM_SET_SIZE: 799 cmd = ASHMEM_SET_SIZE; 800 break; 801 case COMPAT_ASHMEM_SET_PROT_MASK: 802 cmd = ASHMEM_SET_PROT_MASK; 803 break; 804 } 805 return ashmem_ioctl(file, cmd, arg); 806} 807#endif 808 809static const struct file_operations ashmem_fops = { 810 .owner = THIS_MODULE, 811 .open = ashmem_open, 812 .release = ashmem_release, 813 .read = ashmem_read, 814 .llseek = ashmem_llseek, 815 .mmap = ashmem_mmap, 816 .unlocked_ioctl = ashmem_ioctl, 817#ifdef CONFIG_COMPAT 818 .compat_ioctl = compat_ashmem_ioctl, 819#endif 820}; 821 822static struct miscdevice ashmem_misc = { 823 .minor = MISC_DYNAMIC_MINOR, 824 .name = "ashmem", 825 .fops = &ashmem_fops, 826}; 827 828static int __init ashmem_init(void) 829{ 830 int ret; 831 832 ashmem_area_cachep = kmem_cache_create("ashmem_area_cache", 833 sizeof(struct ashmem_area), 834 0, 0, NULL); 835 if (unlikely(!ashmem_area_cachep)) { 836 pr_err("failed to create slab cache\n"); 837 return -ENOMEM; 838 } 839 840 ashmem_range_cachep = kmem_cache_create("ashmem_range_cache", 841 sizeof(struct ashmem_range), 842 0, 0, NULL); 843 if (unlikely(!ashmem_range_cachep)) { 844 pr_err("failed to create slab cache\n"); 845 return -ENOMEM; 846 } 847 848 ret = misc_register(&ashmem_misc); 849 if (unlikely(ret)) { 850 pr_err("failed to register misc device!\n"); 851 return ret; 852 } 853 854 register_shrinker(&ashmem_shrinker); 855 856 pr_info("initialized\n"); 857 858 return 0; 859} 860 861static void __exit ashmem_exit(void) 862{ 863 int ret; 864 865 unregister_shrinker(&ashmem_shrinker); 866 867 ret = misc_deregister(&ashmem_misc); 868 if (unlikely(ret)) 869 pr_err("failed to unregister misc device!\n"); 870 871 kmem_cache_destroy(ashmem_range_cachep); 872 kmem_cache_destroy(ashmem_area_cachep); 873 874 pr_info("unloaded\n"); 875} 876 877module_init(ashmem_init); 878module_exit(ashmem_exit); 879 880MODULE_LICENSE("GPL"); 881