+++ /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 / users / jedix / linux-maple.git / commitdiff