source: src/linux/universal/linux-4.9/drivers/staging/android/ashmem.c @ 31859

Last change on this file since 31859 was 31859, checked in by brainslayer, 3 months ago

kernel update

File size: 22.7 KB
Line 
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/init.h>
22#include <linux/export.h>
23#include <linux/file.h>
24#include <linux/fs.h>
25#include <linux/falloc.h>
26#include <linux/miscdevice.h>
27#include <linux/security.h>
28#include <linux/mm.h>
29#include <linux/mman.h>
30#include <linux/uaccess.h>
31#include <linux/personality.h>
32#include <linux/bitops.h>
33#include <linux/mutex.h>
34#include <linux/shmem_fs.h>
35#include "ashmem.h"
36
37#define ASHMEM_NAME_PREFIX "dev/ashmem/"
38#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
39#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
40
41/**
42 * struct ashmem_area - The anonymous shared memory area
43 * @name:               The optional name in /proc/pid/maps
44 * @unpinned_list:      The list of all ashmem areas
45 * @file:               The shmem-based backing file
46 * @size:               The size of the mapping, in bytes
47 * @prot_mask:          The allowed protection bits, as vm_flags
48 *
49 * The lifecycle of this structure is from our parent file's open() until
50 * its release(). It is also protected by 'ashmem_mutex'
51 *
52 * Warning: Mappings do NOT pin this structure; It dies on close()
53 */
54struct ashmem_area {
55        char name[ASHMEM_FULL_NAME_LEN];
56        struct list_head unpinned_list;
57        struct file *file;
58        size_t size;
59        unsigned long prot_mask;
60};
61
62/**
63 * struct ashmem_range - A range of unpinned/evictable pages
64 * @lru:                 The entry in the LRU list
65 * @unpinned:            The entry in its area's unpinned list
66 * @asma:                The associated anonymous shared memory area.
67 * @pgstart:             The starting page (inclusive)
68 * @pgend:               The ending page (inclusive)
69 * @purged:              The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED)
70 *
71 * The lifecycle of this structure is from unpin to pin.
72 * It is protected by 'ashmem_mutex'
73 */
74struct ashmem_range {
75        struct list_head lru;
76        struct list_head unpinned;
77        struct ashmem_area *asma;
78        size_t pgstart;
79        size_t pgend;
80        unsigned int purged;
81};
82
83/* LRU list of unpinned pages, protected by ashmem_mutex */
84static LIST_HEAD(ashmem_lru_list);
85
86/*
87 * long lru_count - The count of pages on our LRU list.
88 *
89 * This is protected by ashmem_mutex.
90 */
91static unsigned long lru_count;
92
93/*
94 * ashmem_mutex - protects the list of and each individual ashmem_area
95 *
96 * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
97 */
98static DEFINE_MUTEX(ashmem_mutex);
99
100static struct kmem_cache *ashmem_area_cachep __read_mostly;
101static struct kmem_cache *ashmem_range_cachep __read_mostly;
102
103#define range_size(range) \
104        ((range)->pgend - (range)->pgstart + 1)
105
106#define range_on_lru(range) \
107        ((range)->purged == ASHMEM_NOT_PURGED)
108
109static inline int page_range_subsumes_range(struct ashmem_range *range,
110                                            size_t start, size_t end)
111{
112        return (((range)->pgstart >= (start)) && ((range)->pgend <= (end)));
113}
114
115static inline int page_range_subsumed_by_range(struct ashmem_range *range,
116                                               size_t start, size_t end)
117{
118        return (((range)->pgstart <= (start)) && ((range)->pgend >= (end)));
119}
120
121static inline int page_in_range(struct ashmem_range *range, size_t page)
122{
123        return (((range)->pgstart <= (page)) && ((range)->pgend >= (page)));
124}
125
126static inline int page_range_in_range(struct ashmem_range *range,
127                                      size_t start, size_t end)
128{
129        return (page_in_range(range, start) || page_in_range(range, end) ||
130                page_range_subsumes_range(range, start, end));
131}
132
133static inline int range_before_page(struct ashmem_range *range, size_t page)
134{
135        return ((range)->pgend < (page));
136}
137
138#define PROT_MASK               (PROT_EXEC | PROT_READ | PROT_WRITE)
139
140/**
141 * lru_add() - Adds a range of memory to the LRU list
142 * @range:     The memory range being added.
143 *
144 * The range is first added to the end (tail) of the LRU list.
145 * After this, the size of the range is added to @lru_count
146 */
147static inline void lru_add(struct ashmem_range *range)
148{
149        list_add_tail(&range->lru, &ashmem_lru_list);
150        lru_count += range_size(range);
151}
152
153/**
154 * lru_del() - Removes a range of memory from the LRU list
155 * @range:     The memory range being removed
156 *
157 * The range is first deleted from the LRU list.
158 * After this, the size of the range is removed from @lru_count
159 */
160static inline void lru_del(struct ashmem_range *range)
161{
162        list_del(&range->lru);
163        lru_count -= range_size(range);
164}
165
166/**
167 * range_alloc() - Allocates and initializes a new ashmem_range structure
168 * @asma:          The associated ashmem_area
169 * @prev_range:    The previous ashmem_range in the sorted asma->unpinned list
170 * @purged:        Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
171 * @start:         The starting page (inclusive)
172 * @end:           The ending page (inclusive)
173 *
174 * This function is protected by ashmem_mutex.
175 *
176 * Return: 0 if successful, or -ENOMEM if there is an error
177 */
178static int range_alloc(struct ashmem_area *asma,
179                       struct ashmem_range *prev_range, unsigned int purged,
180                       size_t start, size_t end)
181{
182        struct ashmem_range *range;
183
184        range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
185        if (unlikely(!range))
186                return -ENOMEM;
187
188        range->asma = asma;
189        range->pgstart = start;
190        range->pgend = end;
191        range->purged = purged;
192
193        list_add_tail(&range->unpinned, &prev_range->unpinned);
194
195        if (range_on_lru(range))
196                lru_add(range);
197
198        return 0;
199}
200
201/**
202 * range_del() - Deletes and dealloctes an ashmem_range structure
203 * @range:       The associated ashmem_range that has previously been allocated
204 */
205static void range_del(struct ashmem_range *range)
206{
207        list_del(&range->unpinned);
208        if (range_on_lru(range))
209                lru_del(range);
210        kmem_cache_free(ashmem_range_cachep, range);
211}
212
213/**
214 * range_shrink() - Shrinks an ashmem_range
215 * @range:          The associated ashmem_range being shrunk
216 * @start:          The starting byte of the new range
217 * @end:            The ending byte of the new range
218 *
219 * This does not modify the data inside the existing range in any way - It
220 * simply shrinks the boundaries of the range.
221 *
222 * Theoretically, with a little tweaking, this could eventually be changed
223 * to range_resize, and expand the lru_count if the new range is larger.
224 */
225static inline void range_shrink(struct ashmem_range *range,
226                                size_t start, size_t end)
227{
228        size_t pre = range_size(range);
229
230        range->pgstart = start;
231        range->pgend = end;
232
233        if (range_on_lru(range))
234                lru_count -= pre - range_size(range);
235}
236
237/**
238 * ashmem_open() - Opens an Anonymous Shared Memory structure
239 * @inode:         The backing file's index node(?)
240 * @file:          The backing file
241 *
242 * Please note that the ashmem_area is not returned by this function - It is
243 * instead written to "file->private_data".
244 *
245 * Return: 0 if successful, or another code if unsuccessful.
246 */
247static int ashmem_open(struct inode *inode, struct file *file)
248{
249        struct ashmem_area *asma;
250        int ret;
251
252        ret = generic_file_open(inode, file);
253        if (unlikely(ret))
254                return ret;
255
256        asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
257        if (unlikely(!asma))
258                return -ENOMEM;
259
260        INIT_LIST_HEAD(&asma->unpinned_list);
261        memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
262        asma->prot_mask = PROT_MASK;
263        file->private_data = asma;
264
265        return 0;
266}
267
268/**
269 * ashmem_release() - Releases an Anonymous Shared Memory structure
270 * @ignored:          The backing file's Index Node(?) - It is ignored here.
271 * @file:             The backing file
272 *
273 * Return: 0 if successful. If it is anything else, go have a coffee and
274 * try again.
275 */
276static int ashmem_release(struct inode *ignored, struct file *file)
277{
278        struct ashmem_area *asma = file->private_data;
279        struct ashmem_range *range, *next;
280
281        mutex_lock(&ashmem_mutex);
282        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
283                range_del(range);
284        mutex_unlock(&ashmem_mutex);
285
286        if (asma->file)
287                fput(asma->file);
288        kmem_cache_free(ashmem_area_cachep, asma);
289
290        return 0;
291}
292
293/**
294 * ashmem_read() - Reads a set of bytes from an Ashmem-enabled file
295 * @file:          The associated backing file.
296 * @buf:           The buffer of data being written to
297 * @len:           The number of bytes being read
298 * @pos:           The position of the first byte to read.
299 *
300 * Return: 0 if successful, or another return code if not.
301 */
302static ssize_t ashmem_read(struct file *file, char __user *buf,
303                           size_t len, loff_t *pos)
304{
305        struct ashmem_area *asma = file->private_data;
306        int ret = 0;
307
308        mutex_lock(&ashmem_mutex);
309
310        /* If size is not set, or set to 0, always return EOF. */
311        if (asma->size == 0)
312                goto out_unlock;
313
314        if (!asma->file) {
315                ret = -EBADF;
316                goto out_unlock;
317        }
318
319        mutex_unlock(&ashmem_mutex);
320
321        /*
322         * asma and asma->file are used outside the lock here.  We assume
323         * once asma->file is set it will never be changed, and will not
324         * be destroyed until all references to the file are dropped and
325         * ashmem_release is called.
326         */
327        ret = __vfs_read(asma->file, buf, len, pos);
328        if (ret >= 0)
329                /** Update backing file pos, since f_ops->read() doesn't */
330                asma->file->f_pos = *pos;
331        return ret;
332
333out_unlock:
334        mutex_unlock(&ashmem_mutex);
335        return ret;
336}
337
338static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
339{
340        struct ashmem_area *asma = file->private_data;
341        int ret;
342
343        mutex_lock(&ashmem_mutex);
344
345        if (asma->size == 0) {
346                ret = -EINVAL;
347                goto out;
348        }
349
350        if (!asma->file) {
351                ret = -EBADF;
352                goto out;
353        }
354
355        ret = vfs_llseek(asma->file, offset, origin);
356        if (ret < 0)
357                goto out;
358
359        /** Copy f_pos from backing file, since f_ops->llseek() sets it */
360        file->f_pos = asma->file->f_pos;
361
362out:
363        mutex_unlock(&ashmem_mutex);
364        return ret;
365}
366
367static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
368{
369        return _calc_vm_trans(prot, PROT_READ,  VM_MAYREAD) |
370               _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
371               _calc_vm_trans(prot, PROT_EXEC,  VM_MAYEXEC);
372}
373
374static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
375{
376        struct ashmem_area *asma = file->private_data;
377        int ret = 0;
378
379        mutex_lock(&ashmem_mutex);
380
381        /* user needs to SET_SIZE before mapping */
382        if (unlikely(!asma->size)) {
383                ret = -EINVAL;
384                goto out;
385        }
386
387        /* requested protection bits must match our allowed protection mask */
388        if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
389                     calc_vm_prot_bits(PROT_MASK, 0))) {
390                ret = -EPERM;
391                goto out;
392        }
393        vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
394
395        if (!asma->file) {
396                char *name = ASHMEM_NAME_DEF;
397                struct file *vmfile;
398
399                if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
400                        name = asma->name;
401
402                /* ... and allocate the backing shmem file */
403                vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
404                if (IS_ERR(vmfile)) {
405                        ret = PTR_ERR(vmfile);
406                        goto out;
407                }
408                vmfile->f_mode |= FMODE_LSEEK;
409                asma->file = vmfile;
410        }
411        get_file(asma->file);
412
413        /*
414         * XXX - Reworked to use shmem_zero_setup() instead of
415         * shmem_set_file while we're in staging. -jstultz
416         */
417        if (vma->vm_flags & VM_SHARED) {
418                ret = shmem_zero_setup(vma);
419                if (ret) {
420                        fput(asma->file);
421                        goto out;
422                }
423        }
424
425        if (vma->vm_file)
426                fput(vma->vm_file);
427        vma->vm_file = asma->file;
428
429out:
430        mutex_unlock(&ashmem_mutex);
431        return ret;
432}
433
434/*
435 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c
436 *
437 * 'nr_to_scan' is the number of objects to scan for freeing.
438 *
439 * 'gfp_mask' is the mask of the allocation that got us into this mess.
440 *
441 * Return value is the number of objects freed or -1 if we cannot
442 * proceed without risk of deadlock (due to gfp_mask).
443 *
444 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
445 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
446 * pages freed.
447 */
448static unsigned long
449ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
450{
451        struct ashmem_range *range, *next;
452        unsigned long freed = 0;
453
454        /* We might recurse into filesystem code, so bail out if necessary */
455        if (!(sc->gfp_mask & __GFP_FS))
456                return SHRINK_STOP;
457
458        if (!mutex_trylock(&ashmem_mutex))
459                return -1;
460
461        list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
462                loff_t start = range->pgstart * PAGE_SIZE;
463                loff_t end = (range->pgend + 1) * PAGE_SIZE;
464
465                vfs_fallocate(range->asma->file,
466                              FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
467                              start, end - start);
468                range->purged = ASHMEM_WAS_PURGED;
469                lru_del(range);
470
471                freed += range_size(range);
472                if (--sc->nr_to_scan <= 0)
473                        break;
474        }
475        mutex_unlock(&ashmem_mutex);
476        return freed;
477}
478
479static unsigned long
480ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
481{
482        /*
483         * note that lru_count is count of pages on the lru, not a count of
484         * objects on the list. This means the scan function needs to return the
485         * number of pages freed, not the number of objects scanned.
486         */
487        return lru_count;
488}
489
490static struct shrinker ashmem_shrinker = {
491        .count_objects = ashmem_shrink_count,
492        .scan_objects = ashmem_shrink_scan,
493        /*
494         * XXX (dchinner): I wish people would comment on why they need on
495         * significant changes to the default value here
496         */
497        .seeks = DEFAULT_SEEKS * 4,
498};
499
500static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
501{
502        int ret = 0;
503
504        mutex_lock(&ashmem_mutex);
505
506        /* the user can only remove, not add, protection bits */
507        if (unlikely((asma->prot_mask & prot) != prot)) {
508                ret = -EINVAL;
509                goto out;
510        }
511
512        /* does the application expect PROT_READ to imply PROT_EXEC? */
513        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
514                prot |= PROT_EXEC;
515
516        asma->prot_mask = prot;
517
518out:
519        mutex_unlock(&ashmem_mutex);
520        return ret;
521}
522
523static int set_name(struct ashmem_area *asma, void __user *name)
524{
525        int len;
526        int ret = 0;
527        char local_name[ASHMEM_NAME_LEN];
528
529        /*
530         * Holding the ashmem_mutex while doing a copy_from_user might cause
531         * an data abort which would try to access mmap_sem. If another
532         * thread has invoked ashmem_mmap then it will be holding the
533         * semaphore and will be waiting for ashmem_mutex, there by leading to
534         * deadlock. We'll release the mutex  and take the name to a local
535         * variable that does not need protection and later copy the local
536         * variable to the structure member with lock held.
537         */
538        len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN);
539        if (len < 0)
540                return len;
541        if (len == ASHMEM_NAME_LEN)
542                local_name[ASHMEM_NAME_LEN - 1] = '\0';
543        mutex_lock(&ashmem_mutex);
544        /* cannot change an existing mapping's name */
545        if (unlikely(asma->file))
546                ret = -EINVAL;
547        else
548                strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
549
550        mutex_unlock(&ashmem_mutex);
551        return ret;
552}
553
554static int get_name(struct ashmem_area *asma, void __user *name)
555{
556        int ret = 0;
557        size_t len;
558        /*
559         * Have a local variable to which we'll copy the content
560         * from asma with the lock held. Later we can copy this to the user
561         * space safely without holding any locks. So even if we proceed to
562         * wait for mmap_sem, it won't lead to deadlock.
563         */
564        char local_name[ASHMEM_NAME_LEN];
565
566        mutex_lock(&ashmem_mutex);
567        if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
568                /*
569                 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
570                 * prevents us from revealing one user's stack to another.
571                 */
572                len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
573                memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len);
574        } else {
575                len = sizeof(ASHMEM_NAME_DEF);
576                memcpy(local_name, ASHMEM_NAME_DEF, len);
577        }
578        mutex_unlock(&ashmem_mutex);
579
580        /*
581         * Now we are just copying from the stack variable to userland
582         * No lock held
583         */
584        if (unlikely(copy_to_user(name, local_name, len)))
585                ret = -EFAULT;
586        return ret;
587}
588
589/*
590 * ashmem_pin - pin the given ashmem region, returning whether it was
591 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
592 *
593 * Caller must hold ashmem_mutex.
594 */
595static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
596{
597        struct ashmem_range *range, *next;
598        int ret = ASHMEM_NOT_PURGED;
599
600        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
601                /* moved past last applicable page; we can short circuit */
602                if (range_before_page(range, pgstart))
603                        break;
604
605                /*
606                 * The user can ask us to pin pages that span multiple ranges,
607                 * or to pin pages that aren't even unpinned, so this is messy.
608                 *
609                 * Four cases:
610                 * 1. The requested range subsumes an existing range, so we
611                 *    just remove the entire matching range.
612                 * 2. The requested range overlaps the start of an existing
613                 *    range, so we just update that range.
614                 * 3. The requested range overlaps the end of an existing
615                 *    range, so we just update that range.
616                 * 4. The requested range punches a hole in an existing range,
617                 *    so we have to update one side of the range and then
618                 *    create a new range for the other side.
619                 */
620                if (page_range_in_range(range, pgstart, pgend)) {
621                        ret |= range->purged;
622
623                        /* Case #1: Easy. Just nuke the whole thing. */
624                        if (page_range_subsumes_range(range, pgstart, pgend)) {
625                                range_del(range);
626                                continue;
627                        }
628
629                        /* Case #2: We overlap from the start, so adjust it */
630                        if (range->pgstart >= pgstart) {
631                                range_shrink(range, pgend + 1, range->pgend);
632                                continue;
633                        }
634
635                        /* Case #3: We overlap from the rear, so adjust it */
636                        if (range->pgend <= pgend) {
637                                range_shrink(range, range->pgstart,
638                                             pgstart - 1);
639                                continue;
640                        }
641
642                        /*
643                         * Case #4: We eat a chunk out of the middle. A bit
644                         * more complicated, we allocate a new range for the
645                         * second half and adjust the first chunk's endpoint.
646                         */
647                        range_alloc(asma, range, range->purged,
648                                    pgend + 1, range->pgend);
649                        range_shrink(range, range->pgstart, pgstart - 1);
650                        break;
651                }
652        }
653
654        return ret;
655}
656
657/*
658 * ashmem_unpin - unpin the given range of pages. Returns zero on success.
659 *
660 * Caller must hold ashmem_mutex.
661 */
662static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
663{
664        struct ashmem_range *range, *next;
665        unsigned int purged = ASHMEM_NOT_PURGED;
666
667restart:
668        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
669                /* short circuit: this is our insertion point */
670                if (range_before_page(range, pgstart))
671                        break;
672
673                /*
674                 * The user can ask us to unpin pages that are already entirely
675                 * or partially pinned. We handle those two cases here.
676                 */
677                if (page_range_subsumed_by_range(range, pgstart, pgend))
678                        return 0;
679                if (page_range_in_range(range, pgstart, pgend)) {
680                        pgstart = min(range->pgstart, pgstart);
681                        pgend = max(range->pgend, pgend);
682                        purged |= range->purged;
683                        range_del(range);
684                        goto restart;
685                }
686        }
687
688        return range_alloc(asma, range, purged, pgstart, pgend);
689}
690
691/*
692 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
693 * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
694 *
695 * Caller must hold ashmem_mutex.
696 */
697static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
698                                 size_t pgend)
699{
700        struct ashmem_range *range;
701        int ret = ASHMEM_IS_PINNED;
702
703        list_for_each_entry(range, &asma->unpinned_list, unpinned) {
704                if (range_before_page(range, pgstart))
705                        break;
706                if (page_range_in_range(range, pgstart, pgend)) {
707                        ret = ASHMEM_IS_UNPINNED;
708                        break;
709                }
710        }
711
712        return ret;
713}
714
715static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
716                            void __user *p)
717{
718        struct ashmem_pin pin;
719        size_t pgstart, pgend;
720        int ret = -EINVAL;
721
722        if (unlikely(!asma->file))
723                return -EINVAL;
724
725        if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
726                return -EFAULT;
727
728        /* per custom, you can pass zero for len to mean "everything onward" */
729        if (!pin.len)
730                pin.len = PAGE_ALIGN(asma->size) - pin.offset;
731
732        if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
733                return -EINVAL;
734
735        if (unlikely(((__u32)-1) - pin.offset < pin.len))
736                return -EINVAL;
737
738        if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
739                return -EINVAL;
740
741        pgstart = pin.offset / PAGE_SIZE;
742        pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
743
744        mutex_lock(&ashmem_mutex);
745
746        switch (cmd) {
747        case ASHMEM_PIN:
748                ret = ashmem_pin(asma, pgstart, pgend);
749                break;
750        case ASHMEM_UNPIN:
751                ret = ashmem_unpin(asma, pgstart, pgend);
752                break;
753        case ASHMEM_GET_PIN_STATUS:
754                ret = ashmem_get_pin_status(asma, pgstart, pgend);
755                break;
756        }
757
758        mutex_unlock(&ashmem_mutex);
759
760        return ret;
761}
762
763static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
764{
765        struct ashmem_area *asma = file->private_data;
766        long ret = -ENOTTY;
767
768        switch (cmd) {
769        case ASHMEM_SET_NAME:
770                ret = set_name(asma, (void __user *)arg);
771                break;
772        case ASHMEM_GET_NAME:
773                ret = get_name(asma, (void __user *)arg);
774                break;
775        case ASHMEM_SET_SIZE:
776                ret = -EINVAL;
777                if (!asma->file) {
778                        ret = 0;
779                        asma->size = (size_t)arg;
780                }
781                break;
782        case ASHMEM_GET_SIZE:
783                ret = asma->size;
784                break;
785        case ASHMEM_SET_PROT_MASK:
786                ret = set_prot_mask(asma, arg);
787                break;
788        case ASHMEM_GET_PROT_MASK:
789                ret = asma->prot_mask;
790                break;
791        case ASHMEM_PIN:
792        case ASHMEM_UNPIN:
793        case ASHMEM_GET_PIN_STATUS:
794                ret = ashmem_pin_unpin(asma, cmd, (void __user *)arg);
795                break;
796        case ASHMEM_PURGE_ALL_CACHES:
797                ret = -EPERM;
798                if (capable(CAP_SYS_ADMIN)) {
799                        struct shrink_control sc = {
800                                .gfp_mask = GFP_KERNEL,
801                                .nr_to_scan = LONG_MAX,
802                        };
803                        ret = ashmem_shrink_count(&ashmem_shrinker, &sc);
804                        ashmem_shrink_scan(&ashmem_shrinker, &sc);
805                }
806                break;
807        }
808
809        return ret;
810}
811
812/* support of 32bit userspace on 64bit platforms */
813#ifdef CONFIG_COMPAT
814static long compat_ashmem_ioctl(struct file *file, unsigned int cmd,
815                                unsigned long arg)
816{
817        switch (cmd) {
818        case COMPAT_ASHMEM_SET_SIZE:
819                cmd = ASHMEM_SET_SIZE;
820                break;
821        case COMPAT_ASHMEM_SET_PROT_MASK:
822                cmd = ASHMEM_SET_PROT_MASK;
823                break;
824        }
825        return ashmem_ioctl(file, cmd, arg);
826}
827#endif
828
829static const struct file_operations ashmem_fops = {
830        .owner = THIS_MODULE,
831        .open = ashmem_open,
832        .release = ashmem_release,
833        .read = ashmem_read,
834        .llseek = ashmem_llseek,
835        .mmap = ashmem_mmap,
836        .unlocked_ioctl = ashmem_ioctl,
837#ifdef CONFIG_COMPAT
838        .compat_ioctl = compat_ashmem_ioctl,
839#endif
840};
841
842static struct miscdevice ashmem_misc = {
843        .minor = MISC_DYNAMIC_MINOR,
844        .name = "ashmem",
845        .fops = &ashmem_fops,
846};
847
848static int __init ashmem_init(void)
849{
850        int ret = -ENOMEM;
851
852        ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
853                                               sizeof(struct ashmem_area),
854                                               0, 0, NULL);
855        if (unlikely(!ashmem_area_cachep)) {
856                pr_err("failed to create slab cache\n");
857                goto out;
858        }
859
860        ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
861                                                sizeof(struct ashmem_range),
862                                                0, 0, NULL);
863        if (unlikely(!ashmem_range_cachep)) {
864                pr_err("failed to create slab cache\n");
865                goto out_free1;
866        }
867
868        ret = misc_register(&ashmem_misc);
869        if (unlikely(ret)) {
870                pr_err("failed to register misc device!\n");
871                goto out_free2;
872        }
873
874        register_shrinker(&ashmem_shrinker);
875
876        pr_info("initialized\n");
877
878        return 0;
879
880out_free2:
881        kmem_cache_destroy(ashmem_range_cachep);
882out_free1:
883        kmem_cache_destroy(ashmem_area_cachep);
884out:
885        return ret;
886}
887device_initcall(ashmem_init);
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