--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/* mm/ashmem.c
+ *
+ * Anonymous Shared Memory Subsystem, ashmem
+ *
+ * Copyright (C) 2008 Google, Inc.
+ *
+ * Robert Love <rlove@google.com>
+ */
+
+#define pr_fmt(fmt) "ashmem: " fmt
+
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/falloc.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)
+
+/**
+ * struct ashmem_area - The anonymous shared memory area
+ * @name: The optional name in /proc/pid/maps
+ * @unpinned_list: The list of all ashmem areas
+ * @file: The shmem-based backing file
+ * @size: The size of the mapping, in bytes
+ * @prot_mask: The allowed protection bits, as vm_flags
+ *
+ * The lifecycle of this structure is from our parent file's open() until
+ * its release(). It is also protected by 'ashmem_mutex'
+ *
+ * Warning: Mappings do NOT pin this structure; It dies on close()
+ */
+struct ashmem_area {
+ char name[ASHMEM_FULL_NAME_LEN];
+ struct list_head unpinned_list;
+ struct file *file;
+ size_t size;
+ unsigned long prot_mask;
+};
+
+/**
+ * struct ashmem_range - A range of unpinned/evictable pages
+ * @lru: The entry in the LRU list
+ * @unpinned: The entry in its area's unpinned list
+ * @asma: The associated anonymous shared memory area.
+ * @pgstart: The starting page (inclusive)
+ * @pgend: The ending page (inclusive)
+ * @purged: The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED)
+ *
+ * The lifecycle of this structure is from unpin to pin.
+ * It is protected by 'ashmem_mutex'
+ */
+struct ashmem_range {
+ struct list_head lru;
+ struct list_head unpinned;
+ struct ashmem_area *asma;
+ size_t pgstart;
+ size_t pgend;
+ unsigned int purged;
+};
+
+/* LRU list of unpinned pages, protected by ashmem_mutex */
+static LIST_HEAD(ashmem_lru_list);
+
+static atomic_t ashmem_shrink_inflight = ATOMIC_INIT(0);
+static DECLARE_WAIT_QUEUE_HEAD(ashmem_shrink_wait);
+
+/*
+ * long lru_count - The count of pages on our LRU list.
+ *
+ * This is 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;
+
+/*
+ * A separate lockdep class for the backing shmem inodes to resolve the lockdep
+ * warning about the race between kswapd taking fs_reclaim before inode_lock
+ * and write syscall taking inode_lock and then fs_reclaim.
+ * Note that such race is impossible because ashmem does not support write
+ * syscalls operating on the backing shmem.
+ */
+static struct lock_class_key backing_shmem_inode_class;
+
+static inline unsigned long range_size(struct ashmem_range *range)
+{
+ return range->pgend - range->pgstart + 1;
+}
+
+static inline bool range_on_lru(struct ashmem_range *range)
+{
+ return range->purged == ASHMEM_NOT_PURGED;
+}
+
+static inline bool page_range_subsumes_range(struct ashmem_range *range,
+ size_t start, size_t end)
+{
+ return (range->pgstart >= start) && (range->pgend <= end);
+}
+
+static inline bool page_range_subsumed_by_range(struct ashmem_range *range,
+ size_t start, size_t end)
+{
+ return (range->pgstart <= start) && (range->pgend >= end);
+}
+
+static inline bool page_in_range(struct ashmem_range *range, size_t page)
+{
+ return (range->pgstart <= page) && (range->pgend >= page);
+}
+
+static inline bool page_range_in_range(struct ashmem_range *range,
+ size_t start, size_t end)
+{
+ return page_in_range(range, start) || page_in_range(range, end) ||
+ page_range_subsumes_range(range, start, end);
+}
+
+static inline bool range_before_page(struct ashmem_range *range,
+ size_t page)
+{
+ return range->pgend < page;
+}
+
+#define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE)
+
+/**
+ * lru_add() - Adds a range of memory to the LRU list
+ * @range: The memory range being added.
+ *
+ * The range is first added to the end (tail) of the LRU list.
+ * After this, the size of the range is added to @lru_count
+ */
+static inline void lru_add(struct ashmem_range *range)
+{
+ list_add_tail(&range->lru, &ashmem_lru_list);
+ lru_count += range_size(range);
+}
+
+/**
+ * lru_del() - Removes a range of memory from the LRU list
+ * @range: The memory range being removed
+ *
+ * The range is first deleted from the LRU list.
+ * After this, the size of the range is removed from @lru_count
+ */
+static inline void lru_del(struct ashmem_range *range)
+{
+ list_del(&range->lru);
+ lru_count -= range_size(range);
+}
+
+/**
+ * range_alloc() - Allocates and initializes a new ashmem_range structure
+ * @asma: The associated ashmem_area
+ * @prev_range: The previous ashmem_range in the sorted asma->unpinned list
+ * @purged: Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
+ * @start: The starting page (inclusive)
+ * @end: The ending page (inclusive)
+ * @new_range: The placeholder for the new range
+ *
+ * This function is protected by ashmem_mutex.
+ */
+static void range_alloc(struct ashmem_area *asma,
+ struct ashmem_range *prev_range, unsigned int purged,
+ size_t start, size_t end,
+ struct ashmem_range **new_range)
+{
+ struct ashmem_range *range = *new_range;
+
+ *new_range = NULL;
+ 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);
+}
+
+/**
+ * range_del() - Deletes and deallocates an ashmem_range structure
+ * @range: The associated ashmem_range that has previously been allocated
+ */
+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 an ashmem_range
+ * @range: The associated ashmem_range being shrunk
+ * @start: The starting byte of the new range
+ * @end: The ending byte of the new range
+ *
+ * This does not modify the data inside the existing range in any way - It
+ * simply shrinks the boundaries of the range.
+ *
+ * Theoretically, with a little tweaking, this could eventually be changed
+ * to range_resize, and expand the lru_count if the new range is larger.
+ */
+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);
+}
+
+/**
+ * ashmem_open() - Opens an Anonymous Shared Memory structure
+ * @inode: The backing file's index node(?)
+ * @file: The backing file
+ *
+ * Please note that the ashmem_area is not returned by this function - It is
+ * instead written to "file->private_data".
+ *
+ * Return: 0 if successful, or another code if unsuccessful.
+ */
+static int ashmem_open(struct inode *inode, struct file *file)
+{
+ struct ashmem_area *asma;
+ int ret;
+
+ ret = generic_file_open(inode, file);
+ if (ret)
+ return ret;
+
+ asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
+ if (!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;
+}
+
+/**
+ * ashmem_release() - Releases an Anonymous Shared Memory structure
+ * @ignored: The backing file's Index Node(?) - It is ignored here.
+ * @file: The backing file
+ *
+ * Return: 0 if successful. If it is anything else, go have a coffee and
+ * try again.
+ */
+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 ssize_t ashmem_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct ashmem_area *asma = iocb->ki_filp->private_data;
+ int ret = 0;
+
+ mutex_lock(&ashmem_mutex);
+
+ /* If size is not set, or set to 0, always return EOF. */
+ if (asma->size == 0)
+ goto out_unlock;
+
+ if (!asma->file) {
+ ret = -EBADF;
+ goto out_unlock;
+ }
+
+ /*
+ * asma and asma->file are used outside the lock here. We assume
+ * once asma->file is set it will never be changed, and will not
+ * be destroyed until all references to the file are dropped and
+ * ashmem_release is called.
+ */
+ mutex_unlock(&ashmem_mutex);
+ ret = vfs_iter_read(asma->file, iter, &iocb->ki_pos, 0);
+ mutex_lock(&ashmem_mutex);
+ if (ret > 0)
+ asma->file->f_pos = iocb->ki_pos;
+out_unlock:
+ mutex_unlock(&ashmem_mutex);
+ return ret;
+}
+
+static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
+{
+ struct ashmem_area *asma = file->private_data;
+ loff_t ret;
+
+ mutex_lock(&ashmem_mutex);
+
+ if (asma->size == 0) {
+ mutex_unlock(&ashmem_mutex);
+ return -EINVAL;
+ }
+
+ if (!asma->file) {
+ mutex_unlock(&ashmem_mutex);
+ return -EBADF;
+ }
+
+ mutex_unlock(&ashmem_mutex);
+
+ ret = vfs_llseek(asma->file, offset, origin);
+ if (ret < 0)
+ return ret;
+
+ /** Copy f_pos from backing file, since f_ops->llseek() sets it */
+ file->f_pos = asma->file->f_pos;
+ return ret;
+}
+
+static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
+{
+ return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) |
+ _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
+ _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC);
+}
+
+static int ashmem_vmfile_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ /* do not allow to mmap ashmem backing shmem file directly */
+ return -EPERM;
+}
+
+static unsigned long
+ashmem_vmfile_get_unmapped_area(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
+}
+
+static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ static struct file_operations vmfile_fops;
+ struct ashmem_area *asma = file->private_data;
+ int ret = 0;
+
+ mutex_lock(&ashmem_mutex);
+
+ /* user needs to SET_SIZE before mapping */
+ if (!asma->size) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* requested mapping size larger than object size */
+ if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* requested protection bits must match our allowed protection mask */
+ if ((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
+ calc_vm_prot_bits(PROT_MASK, 0)) {
+ ret = -EPERM;
+ goto out;
+ }
+ vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
+
+ if (!asma->file) {
+ char *name = ASHMEM_NAME_DEF;
+ struct file *vmfile;
+ struct inode *inode;
+
+ 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 (IS_ERR(vmfile)) {
+ ret = PTR_ERR(vmfile);
+ goto out;
+ }
+ vmfile->f_mode |= FMODE_LSEEK;
+ inode = file_inode(vmfile);
+ lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
+ asma->file = vmfile;
+ /*
+ * override mmap operation of the vmfile so that it can't be
+ * remapped which would lead to creation of a new vma with no
+ * asma permission checks. Have to override get_unmapped_area
+ * as well to prevent VM_BUG_ON check for f_ops modification.
+ */
+ if (!vmfile_fops.mmap) {
+ vmfile_fops = *vmfile->f_op;
+ vmfile_fops.mmap = ashmem_vmfile_mmap;
+ vmfile_fops.get_unmapped_area =
+ ashmem_vmfile_get_unmapped_area;
+ }
+ vmfile->f_op = &vmfile_fops;
+ }
+ 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;
+ }
+ } else {
+ vma_set_anonymous(vma);
+ }
+
+ vma_set_file(vma, asma->file);
+ /* XXX: merge this with the get_file() above if possible */
+ fput(asma->file);
+
+out:
+ mutex_unlock(&ashmem_mutex);
+ return ret;
+}
+
+/*
+ * ashmem_shrink - our cache shrinker, called from mm/vmscan.c
+ *
+ * 'nr_to_scan' is the number of objects to scan for freeing.
+ *
+ * 'gfp_mask' is the mask of the allocation that got us into this mess.
+ *
+ * Return value is the number of objects freed 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 unsigned long
+ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+ unsigned long freed = 0;
+
+ /* We might recurse into filesystem code, so bail out if necessary */
+ if (!(sc->gfp_mask & __GFP_FS))
+ return SHRINK_STOP;
+
+ if (!mutex_trylock(&ashmem_mutex))
+ return -1;
+
+ while (!list_empty(&ashmem_lru_list)) {
+ struct ashmem_range *range =
+ list_first_entry(&ashmem_lru_list, typeof(*range), lru);
+ loff_t start = range->pgstart * PAGE_SIZE;
+ loff_t end = (range->pgend + 1) * PAGE_SIZE;
+ struct file *f = range->asma->file;
+
+ get_file(f);
+ atomic_inc(&ashmem_shrink_inflight);
+ range->purged = ASHMEM_WAS_PURGED;
+ lru_del(range);
+
+ freed += range_size(range);
+ mutex_unlock(&ashmem_mutex);
+ f->f_op->fallocate(f,
+ FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+ start, end - start);
+ fput(f);
+ if (atomic_dec_and_test(&ashmem_shrink_inflight))
+ wake_up_all(&ashmem_shrink_wait);
+ if (!mutex_trylock(&ashmem_mutex))
+ goto out;
+ if (--sc->nr_to_scan <= 0)
+ break;
+ }
+ mutex_unlock(&ashmem_mutex);
+out:
+ return freed;
+}
+
+static unsigned long
+ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+ /*
+ * note that lru_count is count of pages on the lru, not a count of
+ * objects on the list. This means the scan function needs to return the
+ * number of pages freed, not the number of objects scanned.
+ */
+ return lru_count;
+}
+
+static struct shrinker ashmem_shrinker = {
+ .count_objects = ashmem_shrink_count,
+ .scan_objects = ashmem_shrink_scan,
+ /*
+ * XXX (dchinner): I wish people would comment on why they need on
+ * significant changes to the default value here
+ */
+ .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 ((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 len;
+ int ret = 0;
+ char local_name[ASHMEM_NAME_LEN];
+
+ /*
+ * Holding the ashmem_mutex while doing a copy_from_user might cause
+ * an data abort which would try to access mmap_lock. If another
+ * thread has invoked ashmem_mmap then it will be holding the
+ * semaphore and will be waiting for ashmem_mutex, there by leading to
+ * deadlock. We'll release the mutex and take the name to a local
+ * variable that does not need protection and later copy the local
+ * variable to the structure member with lock held.
+ */
+ len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN);
+ if (len < 0)
+ return len;
+
+ mutex_lock(&ashmem_mutex);
+ /* cannot change an existing mapping's name */
+ if (asma->file)
+ ret = -EINVAL;
+ else
+ strscpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name,
+ ASHMEM_NAME_LEN);
+
+ mutex_unlock(&ashmem_mutex);
+ return ret;
+}
+
+static int get_name(struct ashmem_area *asma, void __user *name)
+{
+ int ret = 0;
+ size_t len;
+ /*
+ * Have a local variable to which we'll copy the content
+ * from asma with the lock held. Later we can copy this to the user
+ * space safely without holding any locks. So even if we proceed to
+ * wait for mmap_lock, it won't lead to deadlock.
+ */
+ char local_name[ASHMEM_NAME_LEN];
+
+ mutex_lock(&ashmem_mutex);
+ if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
+ /*
+ * 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;
+ memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len);
+ } else {
+ len = sizeof(ASHMEM_NAME_DEF);
+ memcpy(local_name, ASHMEM_NAME_DEF, len);
+ }
+ mutex_unlock(&ashmem_mutex);
+
+ /*
+ * Now we are just copying from the stack variable to userland
+ * No lock held
+ */
+ if (copy_to_user(name, local_name, len))
+ ret = -EFAULT;
+ 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 **new_range)
+{
+ 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, new_range);
+ 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 **new_range)
+{
+ 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(range->pgstart, pgstart);
+ pgend = max(range->pgend, pgend);
+ purged |= range->purged;
+ range_del(range);
+ goto restart;
+ }
+ }
+
+ range_alloc(asma, range, purged, pgstart, pgend, new_range);
+ return 0;
+}
+
+/*
+ * 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;
+ struct ashmem_range *range = NULL;
+
+ if (copy_from_user(&pin, p, sizeof(pin)))
+ return -EFAULT;
+
+ if (cmd == ASHMEM_PIN || cmd == ASHMEM_UNPIN) {
+ range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
+ if (!range)
+ return -ENOMEM;
+ }
+
+ mutex_lock(&ashmem_mutex);
+ wait_event(ashmem_shrink_wait, !atomic_read(&ashmem_shrink_inflight));
+
+ if (!asma->file)
+ goto out_unlock;
+
+ /* per custom, you can pass zero for len to mean "everything onward" */
+ if (!pin.len)
+ pin.len = PAGE_ALIGN(asma->size) - pin.offset;
+
+ if ((pin.offset | pin.len) & ~PAGE_MASK)
+ goto out_unlock;
+
+ if (((__u32)-1) - pin.offset < pin.len)
+ goto out_unlock;
+
+ if (PAGE_ALIGN(asma->size) < pin.offset + pin.len)
+ goto out_unlock;
+
+ pgstart = pin.offset / PAGE_SIZE;
+ pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
+
+ switch (cmd) {
+ case ASHMEM_PIN:
+ ret = ashmem_pin(asma, pgstart, pgend, &range);
+ break;
+ case ASHMEM_UNPIN:
+ ret = ashmem_unpin(asma, pgstart, pgend, &range);
+ break;
+ case ASHMEM_GET_PIN_STATUS:
+ ret = ashmem_get_pin_status(asma, pgstart, pgend);
+ break;
+ }
+
+out_unlock:
+ mutex_unlock(&ashmem_mutex);
+ if (range)
+ kmem_cache_free(ashmem_range_cachep, range);
+
+ 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;
+ mutex_lock(&ashmem_mutex);
+ if (!asma->file) {
+ ret = 0;
+ asma->size = (size_t)arg;
+ }
+ mutex_unlock(&ashmem_mutex);
+ 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)) {
+ struct shrink_control sc = {
+ .gfp_mask = GFP_KERNEL,
+ .nr_to_scan = LONG_MAX,
+ };
+ ret = ashmem_shrink_count(&ashmem_shrinker, &sc);
+ ashmem_shrink_scan(&ashmem_shrinker, &sc);
+ }
+ break;
+ }
+
+ return ret;
+}
+
+/* support of 32bit userspace on 64bit platforms */
+#ifdef CONFIG_COMPAT
+static long compat_ashmem_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ switch (cmd) {
+ case COMPAT_ASHMEM_SET_SIZE:
+ cmd = ASHMEM_SET_SIZE;
+ break;
+ case COMPAT_ASHMEM_SET_PROT_MASK:
+ cmd = ASHMEM_SET_PROT_MASK;
+ break;
+ }
+ return ashmem_ioctl(file, cmd, arg);
+}
+#endif
+#ifdef CONFIG_PROC_FS
+static void ashmem_show_fdinfo(struct seq_file *m, struct file *file)
+{
+ struct ashmem_area *asma = file->private_data;
+
+ mutex_lock(&ashmem_mutex);
+
+ if (asma->file)
+ seq_printf(m, "inode:\t%ld\n", file_inode(asma->file)->i_ino);
+
+ if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
+ seq_printf(m, "name:\t%s\n",
+ asma->name + ASHMEM_NAME_PREFIX_LEN);
+
+ seq_printf(m, "size:\t%zu\n", asma->size);
+
+ mutex_unlock(&ashmem_mutex);
+}
+#endif
+static const struct file_operations ashmem_fops = {
+ .owner = THIS_MODULE,
+ .open = ashmem_open,
+ .release = ashmem_release,
+ .read_iter = ashmem_read_iter,
+ .llseek = ashmem_llseek,
+ .mmap = ashmem_mmap,
+ .unlocked_ioctl = ashmem_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = compat_ashmem_ioctl,
+#endif
+#ifdef CONFIG_PROC_FS
+ .show_fdinfo = ashmem_show_fdinfo,
+#endif
+};
+
+static struct miscdevice ashmem_misc = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "ashmem",
+ .fops = &ashmem_fops,
+};
+
+static int __init ashmem_init(void)
+{
+ int ret = -ENOMEM;
+
+ ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
+ sizeof(struct ashmem_area),
+ 0, 0, NULL);
+ if (!ashmem_area_cachep) {
+ pr_err("failed to create slab cache\n");
+ goto out;
+ }
+
+ ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
+ sizeof(struct ashmem_range),
+ 0, SLAB_RECLAIM_ACCOUNT, NULL);
+ if (!ashmem_range_cachep) {
+ pr_err("failed to create slab cache\n");
+ goto out_free1;
+ }
+
+ ret = misc_register(&ashmem_misc);
+ if (ret) {
+ pr_err("failed to register misc device!\n");
+ goto out_free2;
+ }
+
+ ret = register_shrinker(&ashmem_shrinker);
+ if (ret) {
+ pr_err("failed to register shrinker!\n");
+ goto out_demisc;
+ }
+
+ pr_info("initialized\n");
+
+ return 0;
+
+out_demisc:
+ misc_deregister(&ashmem_misc);
+out_free2:
+ kmem_cache_destroy(ashmem_range_cachep);
+out_free1:
+ kmem_cache_destroy(ashmem_area_cachep);
+out:
+ return ret;
+}
+device_initcall(ashmem_init);
projects / platform / kernel / linux-rpi.git / commitdiff