--- /dev/null
+/* mm/ashmem.c
+**
+** Anonymous Shared Memory Subsystem, ashmem
+**
+** Copyright (C) 2008 Google, Inc.
+**
+** Robert Love <rlove@google.com>
+**
+** This software is licensed under the terms of the GNU General Public
+** License version 2, as published by the Free Software Foundation, and
+** may be copied, distributed, and modified under those terms.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+** GNU General Public License for more details.
+*/
+
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/security.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+#include <linux/personality.h>
+#include <linux/bitops.h>
+#include <linux/mutex.h>
+#include <linux/shmem_fs.h>
+#include "ashmem.h"
+
+#define ASHMEM_NAME_PREFIX "dev/ashmem/"
+#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
+#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
+
+/*
+ * ashmem_area - anonymous shared memory area
+ * Lifecycle: From our parent file's open() until its release()
+ * Locking: Protected by `ashmem_mutex'
+ * Big Note: Mappings do NOT pin this structure; it dies on close()
+ */
+struct ashmem_area {
+ char name[ASHMEM_FULL_NAME_LEN];/* optional name for /proc/pid/maps */
+ struct list_head unpinned_list; /* list of all ashmem areas */
+ struct file *file; /* the shmem-based backing file */
+ size_t size; /* size of the mapping, in bytes */
+ unsigned long prot_mask; /* allowed prot bits, as vm_flags */
+};
+
+/*
+ * ashmem_range - represents an interval of unpinned (evictable) pages
+ * Lifecycle: From unpin to pin
+ * Locking: Protected by `ashmem_mutex'
+ */
+struct ashmem_range {
+ struct list_head lru; /* entry in LRU list */
+ struct list_head unpinned; /* entry in its area's unpinned list */
+ struct ashmem_area *asma; /* associated area */
+ size_t pgstart; /* starting page, inclusive */
+ size_t pgend; /* ending page, inclusive */
+ unsigned int purged; /* ASHMEM_NOT or ASHMEM_WAS_PURGED */
+};
+
+/* LRU list of unpinned pages, protected by ashmem_mutex */
+static LIST_HEAD(ashmem_lru_list);
+
+/* Count of pages on our LRU list, protected by ashmem_mutex */
+static unsigned long lru_count;
+
+/*
+ * ashmem_mutex - protects the list of and each individual ashmem_area
+ *
+ * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
+ */
+static DEFINE_MUTEX(ashmem_mutex);
+
+static struct kmem_cache *ashmem_area_cachep __read_mostly;
+static struct kmem_cache *ashmem_range_cachep __read_mostly;
+
+#define range_size(range) \
+ ((range)->pgend - (range)->pgstart + 1)
+
+#define range_on_lru(range) \
+ ((range)->purged == ASHMEM_NOT_PURGED)
+
+#define page_range_subsumes_range(range, start, end) \
+ (((range)->pgstart >= (start)) && ((range)->pgend <= (end)))
+
+#define page_range_subsumed_by_range(range, start, end) \
+ (((range)->pgstart <= (start)) && ((range)->pgend >= (end)))
+
+#define page_in_range(range, page) \
+ (((range)->pgstart <= (page)) && ((range)->pgend >= (page)))
+
+#define page_range_in_range(range, start, end) \
+ (page_in_range(range, start) || page_in_range(range, end) || \
+ page_range_subsumes_range(range, start, end))
+
+#define range_before_page(range, page) \
+ ((range)->pgend < (page))
+
+#define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE)
+
+static inline void lru_add(struct ashmem_range *range)
+{
+ list_add_tail(&range->lru, &ashmem_lru_list);
+ lru_count += range_size(range);
+}
+
+static inline void lru_del(struct ashmem_range *range)
+{
+ list_del(&range->lru);
+ lru_count -= range_size(range);
+}
+
+/*
+ * range_alloc - allocate and initialize a new ashmem_range structure
+ *
+ * 'asma' - associated ashmem_area
+ * 'prev_range' - the previous ashmem_range in the sorted asma->unpinned list
+ * 'purged' - initial purge value (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
+ * 'start' - starting page, inclusive
+ * 'end' - ending page, inclusive
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int range_alloc(struct ashmem_area *asma,
+ struct ashmem_range *prev_range, unsigned int purged,
+ size_t start, size_t end)
+{
+ struct ashmem_range *range;
+
+ range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
+ if (unlikely(!range))
+ return -ENOMEM;
+
+ range->asma = asma;
+ range->pgstart = start;
+ range->pgend = end;
+ range->purged = purged;
+
+ list_add_tail(&range->unpinned, &prev_range->unpinned);
+
+ if (range_on_lru(range))
+ lru_add(range);
+
+ return 0;
+}
+
+static void range_del(struct ashmem_range *range)
+{
+ list_del(&range->unpinned);
+ if (range_on_lru(range))
+ lru_del(range);
+ kmem_cache_free(ashmem_range_cachep, range);
+}
+
+/*
+ * range_shrink - shrinks a range
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static inline void range_shrink(struct ashmem_range *range,
+ size_t start, size_t end)
+{
+ size_t pre = range_size(range);
+
+ range->pgstart = start;
+ range->pgend = end;
+
+ if (range_on_lru(range))
+ lru_count -= pre - range_size(range);
+}
+
+static int ashmem_open(struct inode *inode, struct file *file)
+{
+ struct ashmem_area *asma;
+ int ret;
+
+ ret = nonseekable_open(inode, file);
+ if (unlikely(ret))
+ return ret;
+
+ asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
+ if (unlikely(!asma))
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&asma->unpinned_list);
+ memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
+ asma->prot_mask = PROT_MASK;
+ file->private_data = asma;
+
+ return 0;
+}
+
+static int ashmem_release(struct inode *ignored, struct file *file)
+{
+ struct ashmem_area *asma = file->private_data;
+ struct ashmem_range *range, *next;
+
+ mutex_lock(&ashmem_mutex);
+ list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
+ range_del(range);
+ mutex_unlock(&ashmem_mutex);
+
+ if (asma->file)
+ fput(asma->file);
+ kmem_cache_free(ashmem_area_cachep, asma);
+
+ return 0;
+}
+
+static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct ashmem_area *asma = file->private_data;
+ int ret = 0;
+
+ mutex_lock(&ashmem_mutex);
+
+ /* user needs to SET_SIZE before mapping */
+ if (unlikely(!asma->size)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* requested protection bits must match our allowed protection mask */
+ if (unlikely((vma->vm_flags & ~asma->prot_mask) & PROT_MASK)) {
+ ret = -EPERM;
+ goto out;
+ }
+
+ if (!asma->file) {
+ char *name = ASHMEM_NAME_DEF;
+ struct file *vmfile;
+
+ if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
+ name = asma->name;
+
+ /* ... and allocate the backing shmem file */
+ vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
+ if (unlikely(IS_ERR(vmfile))) {
+ ret = PTR_ERR(vmfile);
+ goto out;
+ }
+ asma->file = vmfile;
+ }
+ get_file(asma->file);
+
+ /*
+ * XXX - Reworked to use shmem_zero_setup() instead of
+ * shmem_set_file while we're in staging. -jstultz
+ */
+ if (vma->vm_flags & VM_SHARED) {
+ ret = shmem_zero_setup(vma);
+ if (ret) {
+ fput(asma->file);
+ goto out;
+ }
+ }
+
+ if (vma->vm_file)
+ fput(vma->vm_file);
+ vma->vm_file = asma->file;
+ vma->vm_flags |= VM_CAN_NONLINEAR;
+
+out:
+ mutex_unlock(&ashmem_mutex);
+ return ret;
+}
+
+/*
+ * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab
+ *
+ * 'nr_to_scan' is the number of objects (pages) to prune, or 0 to query how
+ * many objects (pages) we have in total.
+ *
+ * 'gfp_mask' is the mask of the allocation that got us into this mess.
+ *
+ * Return value is the number of objects (pages) remaining, or -1 if we cannot
+ * proceed without risk of deadlock (due to gfp_mask).
+ *
+ * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
+ * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
+ * pages freed.
+ */
+static int ashmem_shrink(int nr_to_scan, gfp_t gfp_mask)
+{
+ struct ashmem_range *range, *next;
+
+ /* We might recurse into filesystem code, so bail out if necessary */
+ if (nr_to_scan && !(gfp_mask & __GFP_FS))
+ return -1;
+ if (!nr_to_scan)
+ return lru_count;
+
+ mutex_lock(&ashmem_mutex);
+ list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
+ struct inode *inode = range->asma->file->f_dentry->d_inode;
+ loff_t start = range->pgstart * PAGE_SIZE;
+ loff_t end = (range->pgend + 1) * PAGE_SIZE - 1;
+
+ vmtruncate_range(inode, start, end);
+ range->purged = ASHMEM_WAS_PURGED;
+ lru_del(range);
+
+ nr_to_scan -= range_size(range);
+ if (nr_to_scan <= 0)
+ break;
+ }
+ mutex_unlock(&ashmem_mutex);
+
+ return lru_count;
+}
+
+static struct shrinker ashmem_shrinker = {
+ .shrink = ashmem_shrink,
+ .seeks = DEFAULT_SEEKS * 4,
+};
+
+static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
+{
+ int ret = 0;
+
+ mutex_lock(&ashmem_mutex);
+
+ /* the user can only remove, not add, protection bits */
+ if (unlikely((asma->prot_mask & prot) != prot)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* does the application expect PROT_READ to imply PROT_EXEC? */
+ if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+ prot |= PROT_EXEC;
+
+ asma->prot_mask = prot;
+
+out:
+ mutex_unlock(&ashmem_mutex);
+ return ret;
+}
+
+static int set_name(struct ashmem_area *asma, void __user *name)
+{
+ int ret = 0;
+
+ mutex_lock(&ashmem_mutex);
+
+ /* cannot change an existing mapping's name */
+ if (unlikely(asma->file)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (unlikely(copy_from_user(asma->name + ASHMEM_NAME_PREFIX_LEN,
+ name, ASHMEM_NAME_LEN)))
+ ret = -EFAULT;
+ asma->name[ASHMEM_FULL_NAME_LEN-1] = '\0';
+
+out:
+ mutex_unlock(&ashmem_mutex);
+
+ return ret;
+}
+
+static int get_name(struct ashmem_area *asma, void __user *name)
+{
+ int ret = 0;
+
+ mutex_lock(&ashmem_mutex);
+ if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
+ size_t len;
+
+ /*
+ * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
+ * prevents us from revealing one user's stack to another.
+ */
+ len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
+ if (unlikely(copy_to_user(name,
+ asma->name + ASHMEM_NAME_PREFIX_LEN, len)))
+ ret = -EFAULT;
+ } else {
+ if (unlikely(copy_to_user(name, ASHMEM_NAME_DEF,
+ sizeof(ASHMEM_NAME_DEF))))
+ ret = -EFAULT;
+ }
+ mutex_unlock(&ashmem_mutex);
+
+ return ret;
+}
+
+/*
+ * ashmem_pin - pin the given ashmem region, returning whether it was
+ * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
+{
+ struct ashmem_range *range, *next;
+ int ret = ASHMEM_NOT_PURGED;
+
+ list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
+ /* moved past last applicable page; we can short circuit */
+ if (range_before_page(range, pgstart))
+ break;
+
+ /*
+ * The user can ask us to pin pages that span multiple ranges,
+ * or to pin pages that aren't even unpinned, so this is messy.
+ *
+ * Four cases:
+ * 1. The requested range subsumes an existing range, so we
+ * just remove the entire matching range.
+ * 2. The requested range overlaps the start of an existing
+ * range, so we just update that range.
+ * 3. The requested range overlaps the end of an existing
+ * range, so we just update that range.
+ * 4. The requested range punches a hole in an existing range,
+ * so we have to update one side of the range and then
+ * create a new range for the other side.
+ */
+ if (page_range_in_range(range, pgstart, pgend)) {
+ ret |= range->purged;
+
+ /* Case #1: Easy. Just nuke the whole thing. */
+ if (page_range_subsumes_range(range, pgstart, pgend)) {
+ range_del(range);
+ continue;
+ }
+
+ /* Case #2: We overlap from the start, so adjust it */
+ if (range->pgstart >= pgstart) {
+ range_shrink(range, pgend + 1, range->pgend);
+ continue;
+ }
+
+ /* Case #3: We overlap from the rear, so adjust it */
+ if (range->pgend <= pgend) {
+ range_shrink(range, range->pgstart, pgstart-1);
+ continue;
+ }
+
+ /*
+ * Case #4: We eat a chunk out of the middle. A bit
+ * more complicated, we allocate a new range for the
+ * second half and adjust the first chunk's endpoint.
+ */
+ range_alloc(asma, range, range->purged,
+ pgend + 1, range->pgend);
+ range_shrink(range, range->pgstart, pgstart - 1);
+ break;
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * ashmem_unpin - unpin the given range of pages. Returns zero on success.
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
+{
+ struct ashmem_range *range, *next;
+ unsigned int purged = ASHMEM_NOT_PURGED;
+
+restart:
+ list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
+ /* short circuit: this is our insertion point */
+ if (range_before_page(range, pgstart))
+ break;
+
+ /*
+ * The user can ask us to unpin pages that are already entirely
+ * or partially pinned. We handle those two cases here.
+ */
+ if (page_range_subsumed_by_range(range, pgstart, pgend))
+ return 0;
+ if (page_range_in_range(range, pgstart, pgend)) {
+ pgstart = min_t(size_t, range->pgstart, pgstart),
+ pgend = max_t(size_t, range->pgend, pgend);
+ purged |= range->purged;
+ range_del(range);
+ goto restart;
+ }
+ }
+
+ return range_alloc(asma, range, purged, pgstart, pgend);
+}
+
+/*
+ * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
+ * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
+ size_t pgend)
+{
+ struct ashmem_range *range;
+ int ret = ASHMEM_IS_PINNED;
+
+ list_for_each_entry(range, &asma->unpinned_list, unpinned) {
+ if (range_before_page(range, pgstart))
+ break;
+ if (page_range_in_range(range, pgstart, pgend)) {
+ ret = ASHMEM_IS_UNPINNED;
+ break;
+ }
+ }
+
+ return ret;
+}
+
+static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
+ void __user *p)
+{
+ struct ashmem_pin pin;
+ size_t pgstart, pgend;
+ int ret = -EINVAL;
+
+ if (unlikely(!asma->file))
+ return -EINVAL;
+
+ if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
+ return -EFAULT;
+
+ /* per custom, you can pass zero for len to mean "everything onward" */
+ if (!pin.len)
+ pin.len = PAGE_ALIGN(asma->size) - pin.offset;
+
+ if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
+ return -EINVAL;
+
+ if (unlikely(((__u32) -1) - pin.offset < pin.len))
+ return -EINVAL;
+
+ if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
+ return -EINVAL;
+
+ pgstart = pin.offset / PAGE_SIZE;
+ pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
+
+ mutex_lock(&ashmem_mutex);
+
+ switch (cmd) {
+ case ASHMEM_PIN:
+ ret = ashmem_pin(asma, pgstart, pgend);
+ break;
+ case ASHMEM_UNPIN:
+ ret = ashmem_unpin(asma, pgstart, pgend);
+ break;
+ case ASHMEM_GET_PIN_STATUS:
+ ret = ashmem_get_pin_status(asma, pgstart, pgend);
+ break;
+ }
+
+ mutex_unlock(&ashmem_mutex);
+
+ return ret;
+}
+
+static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct ashmem_area *asma = file->private_data;
+ long ret = -ENOTTY;
+
+ switch (cmd) {
+ case ASHMEM_SET_NAME:
+ ret = set_name(asma, (void __user *) arg);
+ break;
+ case ASHMEM_GET_NAME:
+ ret = get_name(asma, (void __user *) arg);
+ break;
+ case ASHMEM_SET_SIZE:
+ ret = -EINVAL;
+ if (!asma->file) {
+ ret = 0;
+ asma->size = (size_t) arg;
+ }
+ break;
+ case ASHMEM_GET_SIZE:
+ ret = asma->size;
+ break;
+ case ASHMEM_SET_PROT_MASK:
+ ret = set_prot_mask(asma, arg);
+ break;
+ case ASHMEM_GET_PROT_MASK:
+ ret = asma->prot_mask;
+ break;
+ case ASHMEM_PIN:
+ case ASHMEM_UNPIN:
+ case ASHMEM_GET_PIN_STATUS:
+ ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg);
+ break;
+ case ASHMEM_PURGE_ALL_CACHES:
+ ret = -EPERM;
+ if (capable(CAP_SYS_ADMIN)) {
+ ret = ashmem_shrink(0, GFP_KERNEL);
+ ashmem_shrink(ret, GFP_KERNEL);
+ }
+ break;
+ }
+
+ return ret;
+}
+
+static struct file_operations ashmem_fops = {
+ .owner = THIS_MODULE,
+ .open = ashmem_open,
+ .release = ashmem_release,
+ .mmap = ashmem_mmap,
+ .unlocked_ioctl = ashmem_ioctl,
+ .compat_ioctl = ashmem_ioctl,
+};
+
+static struct miscdevice ashmem_misc = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "ashmem",
+ .fops = &ashmem_fops,
+};
+
+static int __init ashmem_init(void)
+{
+ int ret;
+
+ ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
+ sizeof(struct ashmem_area),
+ 0, 0, NULL);
+ if (unlikely(!ashmem_area_cachep)) {
+ printk(KERN_ERR "ashmem: failed to create slab cache\n");
+ return -ENOMEM;
+ }
+
+ ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
+ sizeof(struct ashmem_range),
+ 0, 0, NULL);
+ if (unlikely(!ashmem_range_cachep)) {
+ printk(KERN_ERR "ashmem: failed to create slab cache\n");
+ return -ENOMEM;
+ }
+
+ ret = misc_register(&ashmem_misc);
+ if (unlikely(ret)) {
+ printk(KERN_ERR "ashmem: failed to register misc device!\n");
+ return ret;
+ }
+
+ register_shrinker(&ashmem_shrinker);
+
+ printk(KERN_INFO "ashmem: initialized\n");
+
+ return 0;
+}
+
+static void __exit ashmem_exit(void)
+{
+ int ret;
+
+ unregister_shrinker(&ashmem_shrinker);
+
+ ret = misc_deregister(&ashmem_misc);
+ if (unlikely(ret))
+ printk(KERN_ERR "ashmem: failed to unregister misc device!\n");
+
+ kmem_cache_destroy(ashmem_range_cachep);
+ kmem_cache_destroy(ashmem_area_cachep);
+
+ printk(KERN_INFO "ashmem: unloaded\n");
+}
+
+module_init(ashmem_init);
+module_exit(ashmem_exit);
+
+MODULE_LICENSE("GPL");
projects / profile / ivi / kernel-adaptation-intel-automotive.git / commitdiff