source: src/linux/universal/linux-3.18/drivers/staging/android/ashmem.c @ 31869

Last change on this file since 31869 was 31869, checked in by brainslayer, 2 months ago

update

File size: 22.7 KB
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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                vmfile->f_mode |= FMODE_LSEEK;
396                asma->file = vmfile;
397        }
398        get_file(asma->file);
399
400        /*
401         * XXX - Reworked to use shmem_zero_setup() instead of
402         * shmem_set_file while we're in staging. -jstultz
403         */
404        if (vma->vm_flags & VM_SHARED) {
405                ret = shmem_zero_setup(vma);
406                if (ret) {
407                        fput(asma->file);
408                        goto out;
409                }
410        }
411
412        if (vma->vm_file)
413                fput(vma->vm_file);
414        vma->vm_file = asma->file;
415
416out:
417        mutex_unlock(&ashmem_mutex);
418        return ret;
419}
420
421/*
422 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab
423 *
424 * 'nr_to_scan' is the number of objects to scan for freeing.
425 *
426 * 'gfp_mask' is the mask of the allocation that got us into this mess.
427 *
428 * Return value is the number of objects freed or -1 if we cannot
429 * proceed without risk of deadlock (due to gfp_mask).
430 *
431 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
432 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
433 * pages freed.
434 */
435static unsigned long
436ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
437{
438        struct ashmem_range *range, *next;
439        unsigned long freed = 0;
440
441        /* We might recurse into filesystem code, so bail out if necessary */
442        if (!(sc->gfp_mask & __GFP_FS))
443                return SHRINK_STOP;
444
445        mutex_lock(&ashmem_mutex);
446        list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
447                loff_t start = range->pgstart * PAGE_SIZE;
448                loff_t end = (range->pgend + 1) * PAGE_SIZE;
449
450                do_fallocate(range->asma->file,
451                                FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
452                                start, end - start);
453                range->purged = ASHMEM_WAS_PURGED;
454                lru_del(range);
455
456                freed += range_size(range);
457                if (--sc->nr_to_scan <= 0)
458                        break;
459        }
460        mutex_unlock(&ashmem_mutex);
461        return freed;
462}
463
464static unsigned long
465ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
466{
467        /*
468         * note that lru_count is count of pages on the lru, not a count of
469         * objects on the list. This means the scan function needs to return the
470         * number of pages freed, not the number of objects scanned.
471         */
472        return lru_count;
473}
474
475static struct shrinker ashmem_shrinker = {
476        .count_objects = ashmem_shrink_count,
477        .scan_objects = ashmem_shrink_scan,
478        /*
479         * XXX (dchinner): I wish people would comment on why they need on
480         * significant changes to the default value here
481         */
482        .seeks = DEFAULT_SEEKS * 4,
483};
484
485static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
486{
487        int ret = 0;
488
489        mutex_lock(&ashmem_mutex);
490
491        /* the user can only remove, not add, protection bits */
492        if (unlikely((asma->prot_mask & prot) != prot)) {
493                ret = -EINVAL;
494                goto out;
495        }
496
497        /* does the application expect PROT_READ to imply PROT_EXEC? */
498        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
499                prot |= PROT_EXEC;
500
501        asma->prot_mask = prot;
502
503out:
504        mutex_unlock(&ashmem_mutex);
505        return ret;
506}
507
508static int set_name(struct ashmem_area *asma, void __user *name)
509{
510        int len;
511        int ret = 0;
512        char local_name[ASHMEM_NAME_LEN];
513
514        /*
515         * Holding the ashmem_mutex while doing a copy_from_user might cause
516         * an data abort which would try to access mmap_sem. If another
517         * thread has invoked ashmem_mmap then it will be holding the
518         * semaphore and will be waiting for ashmem_mutex, there by leading to
519         * deadlock. We'll release the mutex  and take the name to a local
520         * variable that does not need protection and later copy the local
521         * variable to the structure member with lock held.
522         */
523        len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN);
524        if (len < 0)
525                return len;
526        if (len == ASHMEM_NAME_LEN)
527                local_name[ASHMEM_NAME_LEN - 1] = '\0';
528        mutex_lock(&ashmem_mutex);
529        /* cannot change an existing mapping's name */
530        if (unlikely(asma->file))
531                ret = -EINVAL;
532        else
533                strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
534
535        mutex_unlock(&ashmem_mutex);
536        return ret;
537}
538
539static int get_name(struct ashmem_area *asma, void __user *name)
540{
541        int ret = 0;
542        size_t len;
543        /*
544         * Have a local variable to which we'll copy the content
545         * from asma with the lock held. Later we can copy this to the user
546         * space safely without holding any locks. So even if we proceed to
547         * wait for mmap_sem, it won't lead to deadlock.
548         */
549        char local_name[ASHMEM_NAME_LEN];
550
551        mutex_lock(&ashmem_mutex);
552        if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
553
554                /*
555                 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
556                 * prevents us from revealing one user's stack to another.
557                 */
558                len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
559                memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len);
560        } else {
561                len = sizeof(ASHMEM_NAME_DEF);
562                memcpy(local_name, ASHMEM_NAME_DEF, len);
563        }
564        mutex_unlock(&ashmem_mutex);
565
566        /*
567         * Now we are just copying from the stack variable to userland
568         * No lock held
569         */
570        if (unlikely(copy_to_user(name, local_name, len)))
571                ret = -EFAULT;
572        return ret;
573}
574
575/*
576 * ashmem_pin - pin the given ashmem region, returning whether it was
577 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
578 *
579 * Caller must hold ashmem_mutex.
580 */
581static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
582{
583        struct ashmem_range *range, *next;
584        int ret = ASHMEM_NOT_PURGED;
585
586        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
587                /* moved past last applicable page; we can short circuit */
588                if (range_before_page(range, pgstart))
589                        break;
590
591                /*
592                 * The user can ask us to pin pages that span multiple ranges,
593                 * or to pin pages that aren't even unpinned, so this is messy.
594                 *
595                 * Four cases:
596                 * 1. The requested range subsumes an existing range, so we
597                 *    just remove the entire matching range.
598                 * 2. The requested range overlaps the start of an existing
599                 *    range, so we just update that range.
600                 * 3. The requested range overlaps the end of an existing
601                 *    range, so we just update that range.
602                 * 4. The requested range punches a hole in an existing range,
603                 *    so we have to update one side of the range and then
604                 *    create a new range for the other side.
605                 */
606                if (page_range_in_range(range, pgstart, pgend)) {
607                        ret |= range->purged;
608
609                        /* Case #1: Easy. Just nuke the whole thing. */
610                        if (page_range_subsumes_range(range, pgstart, pgend)) {
611                                range_del(range);
612                                continue;
613                        }
614
615                        /* Case #2: We overlap from the start, so adjust it */
616                        if (range->pgstart >= pgstart) {
617                                range_shrink(range, pgend + 1, range->pgend);
618                                continue;
619                        }
620
621                        /* Case #3: We overlap from the rear, so adjust it */
622                        if (range->pgend <= pgend) {
623                                range_shrink(range, range->pgstart, pgstart-1);
624                                continue;
625                        }
626
627                        /*
628                         * Case #4: We eat a chunk out of the middle. A bit
629                         * more complicated, we allocate a new range for the
630                         * second half and adjust the first chunk's endpoint.
631                         */
632                        range_alloc(asma, range, range->purged,
633                                    pgend + 1, range->pgend);
634                        range_shrink(range, range->pgstart, pgstart - 1);
635                        break;
636                }
637        }
638
639        return ret;
640}
641
642/*
643 * ashmem_unpin - unpin the given range of pages. Returns zero on success.
644 *
645 * Caller must hold ashmem_mutex.
646 */
647static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
648{
649        struct ashmem_range *range, *next;
650        unsigned int purged = ASHMEM_NOT_PURGED;
651
652restart:
653        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
654                /* short circuit: this is our insertion point */
655                if (range_before_page(range, pgstart))
656                        break;
657
658                /*
659                 * The user can ask us to unpin pages that are already entirely
660                 * or partially pinned. We handle those two cases here.
661                 */
662                if (page_range_subsumed_by_range(range, pgstart, pgend))
663                        return 0;
664                if (page_range_in_range(range, pgstart, pgend)) {
665                        pgstart = min_t(size_t, range->pgstart, pgstart),
666                        pgend = max_t(size_t, range->pgend, pgend);
667                        purged |= range->purged;
668                        range_del(range);
669                        goto restart;
670                }
671        }
672
673        return range_alloc(asma, range, purged, pgstart, pgend);
674}
675
676/*
677 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
678 * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
679 *
680 * Caller must hold ashmem_mutex.
681 */
682static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
683                                 size_t pgend)
684{
685        struct ashmem_range *range;
686        int ret = ASHMEM_IS_PINNED;
687
688        list_for_each_entry(range, &asma->unpinned_list, unpinned) {
689                if (range_before_page(range, pgstart))
690                        break;
691                if (page_range_in_range(range, pgstart, pgend)) {
692                        ret = ASHMEM_IS_UNPINNED;
693                        break;
694                }
695        }
696
697        return ret;
698}
699
700static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
701                            void __user *p)
702{
703        struct ashmem_pin pin;
704        size_t pgstart, pgend;
705        int ret = -EINVAL;
706
707        if (unlikely(!asma->file))
708                return -EINVAL;
709
710        if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
711                return -EFAULT;
712
713        /* per custom, you can pass zero for len to mean "everything onward" */
714        if (!pin.len)
715                pin.len = PAGE_ALIGN(asma->size) - pin.offset;
716
717        if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
718                return -EINVAL;
719
720        if (unlikely(((__u32) -1) - pin.offset < pin.len))
721                return -EINVAL;
722
723        if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
724                return -EINVAL;
725
726        pgstart = pin.offset / PAGE_SIZE;
727        pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
728
729        mutex_lock(&ashmem_mutex);
730
731        switch (cmd) {
732        case ASHMEM_PIN:
733                ret = ashmem_pin(asma, pgstart, pgend);
734                break;
735        case ASHMEM_UNPIN:
736                ret = ashmem_unpin(asma, pgstart, pgend);
737                break;
738        case ASHMEM_GET_PIN_STATUS:
739                ret = ashmem_get_pin_status(asma, pgstart, pgend);
740                break;
741        }
742
743        mutex_unlock(&ashmem_mutex);
744
745        return ret;
746}
747
748static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
749{
750        struct ashmem_area *asma = file->private_data;
751        long ret = -ENOTTY;
752
753        switch (cmd) {
754        case ASHMEM_SET_NAME:
755                ret = set_name(asma, (void __user *) arg);
756                break;
757        case ASHMEM_GET_NAME:
758                ret = get_name(asma, (void __user *) arg);
759                break;
760        case ASHMEM_SET_SIZE:
761                ret = -EINVAL;
762                if (!asma->file) {
763                        ret = 0;
764                        asma->size = (size_t) arg;
765                }
766                break;
767        case ASHMEM_GET_SIZE:
768                ret = asma->size;
769                break;
770        case ASHMEM_SET_PROT_MASK:
771                ret = set_prot_mask(asma, arg);
772                break;
773        case ASHMEM_GET_PROT_MASK:
774                ret = asma->prot_mask;
775                break;
776        case ASHMEM_PIN:
777        case ASHMEM_UNPIN:
778        case ASHMEM_GET_PIN_STATUS:
779                ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg);
780                break;
781        case ASHMEM_PURGE_ALL_CACHES:
782                ret = -EPERM;
783                if (capable(CAP_SYS_ADMIN)) {
784                        struct shrink_control sc = {
785                                .gfp_mask = GFP_KERNEL,
786                                .nr_to_scan = LONG_MAX,
787                        };
788                        ret = ashmem_shrink_count(&ashmem_shrinker, &sc);
789                        nodes_setall(sc.nodes_to_scan);
790                        ashmem_shrink_scan(&ashmem_shrinker, &sc);
791                }
792                break;
793        }
794
795        return ret;
796}
797
798/* support of 32bit userspace on 64bit platforms */
799#ifdef CONFIG_COMPAT
800static long compat_ashmem_ioctl(struct file *file, unsigned int cmd,
801                                unsigned long arg)
802{
803
804        switch (cmd) {
805        case COMPAT_ASHMEM_SET_SIZE:
806                cmd = ASHMEM_SET_SIZE;
807                break;
808        case COMPAT_ASHMEM_SET_PROT_MASK:
809                cmd = ASHMEM_SET_PROT_MASK;
810                break;
811        }
812        return ashmem_ioctl(file, cmd, arg);
813}
814#endif
815
816static const struct file_operations ashmem_fops = {
817        .owner = THIS_MODULE,
818        .open = ashmem_open,
819        .release = ashmem_release,
820        .read = ashmem_read,
821        .llseek = ashmem_llseek,
822        .mmap = ashmem_mmap,
823        .unlocked_ioctl = ashmem_ioctl,
824#ifdef CONFIG_COMPAT
825        .compat_ioctl = compat_ashmem_ioctl,
826#endif
827};
828
829static struct miscdevice ashmem_misc = {
830        .minor = MISC_DYNAMIC_MINOR,
831        .name = "ashmem",
832        .fops = &ashmem_fops,
833};
834
835static int __init ashmem_init(void)
836{
837        int ret;
838
839        ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
840                                          sizeof(struct ashmem_area),
841                                          0, 0, NULL);
842        if (unlikely(!ashmem_area_cachep)) {
843                pr_err("failed to create slab cache\n");
844                return -ENOMEM;
845        }
846
847        ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
848                                          sizeof(struct ashmem_range),
849                                          0, 0, NULL);
850        if (unlikely(!ashmem_range_cachep)) {
851                pr_err("failed to create slab cache\n");
852                return -ENOMEM;
853        }
854
855        ret = misc_register(&ashmem_misc);
856        if (unlikely(ret)) {
857                pr_err("failed to register misc device!\n");
858                return ret;
859        }
860
861        register_shrinker(&ashmem_shrinker);
862
863        pr_info("initialized\n");
864
865        return 0;
866}
867
868static void __exit ashmem_exit(void)
869{
870        int ret;
871
872        unregister_shrinker(&ashmem_shrinker);
873
874        ret = misc_deregister(&ashmem_misc);
875        if (unlikely(ret))
876                pr_err("failed to unregister misc device!\n");
877
878        kmem_cache_destroy(ashmem_range_cachep);
879        kmem_cache_destroy(ashmem_area_cachep);
880
881        pr_info("unloaded\n");
882}
883
884module_init(ashmem_init);
885module_exit(ashmem_exit);
886
887MODULE_LICENSE("GPL");
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