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-rw-r--r--drivers/dma-buf/dma-buf.c1734
1 files changed, 1734 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
new file mode 100644
index 0000000000..21916bba77
--- /dev/null
+++ b/drivers/dma-buf/dma-buf.c
@@ -0,0 +1,1734 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Framework for buffer objects that can be shared across devices/subsystems.
+ *
+ * Copyright(C) 2011 Linaro Limited. All rights reserved.
+ * Author: Sumit Semwal <sumit.semwal@ti.com>
+ *
+ * Many thanks to linaro-mm-sig list, and specially
+ * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
+ * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
+ * refining of this idea.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-fence.h>
+#include <linux/dma-fence-unwrap.h>
+#include <linux/anon_inodes.h>
+#include <linux/export.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/sync_file.h>
+#include <linux/poll.h>
+#include <linux/dma-resv.h>
+#include <linux/mm.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+
+#include <uapi/linux/dma-buf.h>
+#include <uapi/linux/magic.h>
+
+#include "dma-buf-sysfs-stats.h"
+
+static inline int is_dma_buf_file(struct file *);
+
+struct dma_buf_list {
+ struct list_head head;
+ struct mutex lock;
+};
+
+static struct dma_buf_list db_list;
+
+static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+ struct dma_buf *dmabuf;
+ char name[DMA_BUF_NAME_LEN];
+ size_t ret = 0;
+
+ dmabuf = dentry->d_fsdata;
+ spin_lock(&dmabuf->name_lock);
+ if (dmabuf->name)
+ ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
+ spin_unlock(&dmabuf->name_lock);
+
+ return dynamic_dname(buffer, buflen, "/%s:%s",
+ dentry->d_name.name, ret > 0 ? name : "");
+}
+
+static void dma_buf_release(struct dentry *dentry)
+{
+ struct dma_buf *dmabuf;
+
+ dmabuf = dentry->d_fsdata;
+ if (unlikely(!dmabuf))
+ return;
+
+ BUG_ON(dmabuf->vmapping_counter);
+
+ /*
+ * If you hit this BUG() it could mean:
+ * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else
+ * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback
+ */
+ BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
+
+ dma_buf_stats_teardown(dmabuf);
+ dmabuf->ops->release(dmabuf);
+
+ if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
+ dma_resv_fini(dmabuf->resv);
+
+ WARN_ON(!list_empty(&dmabuf->attachments));
+ module_put(dmabuf->owner);
+ kfree(dmabuf->name);
+ kfree(dmabuf);
+}
+
+static int dma_buf_file_release(struct inode *inode, struct file *file)
+{
+ struct dma_buf *dmabuf;
+
+ if (!is_dma_buf_file(file))
+ return -EINVAL;
+
+ dmabuf = file->private_data;
+ if (dmabuf) {
+ mutex_lock(&db_list.lock);
+ list_del(&dmabuf->list_node);
+ mutex_unlock(&db_list.lock);
+ }
+
+ return 0;
+}
+
+static const struct dentry_operations dma_buf_dentry_ops = {
+ .d_dname = dmabuffs_dname,
+ .d_release = dma_buf_release,
+};
+
+static struct vfsmount *dma_buf_mnt;
+
+static int dma_buf_fs_init_context(struct fs_context *fc)
+{
+ struct pseudo_fs_context *ctx;
+
+ ctx = init_pseudo(fc, DMA_BUF_MAGIC);
+ if (!ctx)
+ return -ENOMEM;
+ ctx->dops = &dma_buf_dentry_ops;
+ return 0;
+}
+
+static struct file_system_type dma_buf_fs_type = {
+ .name = "dmabuf",
+ .init_fs_context = dma_buf_fs_init_context,
+ .kill_sb = kill_anon_super,
+};
+
+static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
+{
+ struct dma_buf *dmabuf;
+
+ if (!is_dma_buf_file(file))
+ return -EINVAL;
+
+ dmabuf = file->private_data;
+
+ /* check if buffer supports mmap */
+ if (!dmabuf->ops->mmap)
+ return -EINVAL;
+
+ /* check for overflowing the buffer's size */
+ if (vma->vm_pgoff + vma_pages(vma) >
+ dmabuf->size >> PAGE_SHIFT)
+ return -EINVAL;
+
+ return dmabuf->ops->mmap(dmabuf, vma);
+}
+
+static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct dma_buf *dmabuf;
+ loff_t base;
+
+ if (!is_dma_buf_file(file))
+ return -EBADF;
+
+ dmabuf = file->private_data;
+
+ /* only support discovering the end of the buffer,
+ but also allow SEEK_SET to maintain the idiomatic
+ SEEK_END(0), SEEK_CUR(0) pattern */
+ if (whence == SEEK_END)
+ base = dmabuf->size;
+ else if (whence == SEEK_SET)
+ base = 0;
+ else
+ return -EINVAL;
+
+ if (offset != 0)
+ return -EINVAL;
+
+ return base + offset;
+}
+
+/**
+ * DOC: implicit fence polling
+ *
+ * To support cross-device and cross-driver synchronization of buffer access
+ * implicit fences (represented internally in the kernel with &struct dma_fence)
+ * can be attached to a &dma_buf. The glue for that and a few related things are
+ * provided in the &dma_resv structure.
+ *
+ * Userspace can query the state of these implicitly tracked fences using poll()
+ * and related system calls:
+ *
+ * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the
+ * most recent write or exclusive fence.
+ *
+ * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of
+ * all attached fences, shared and exclusive ones.
+ *
+ * Note that this only signals the completion of the respective fences, i.e. the
+ * DMA transfers are complete. Cache flushing and any other necessary
+ * preparations before CPU access can begin still need to happen.
+ *
+ * As an alternative to poll(), the set of fences on DMA buffer can be
+ * exported as a &sync_file using &dma_buf_sync_file_export.
+ */
+
+static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
+ struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
+ struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);
+ unsigned long flags;
+
+ spin_lock_irqsave(&dcb->poll->lock, flags);
+ wake_up_locked_poll(dcb->poll, dcb->active);
+ dcb->active = 0;
+ spin_unlock_irqrestore(&dcb->poll->lock, flags);
+ dma_fence_put(fence);
+ /* Paired with get_file in dma_buf_poll */
+ fput(dmabuf->file);
+}
+
+static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
+ struct dma_buf_poll_cb_t *dcb)
+{
+ struct dma_resv_iter cursor;
+ struct dma_fence *fence;
+ int r;
+
+ dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),
+ fence) {
+ dma_fence_get(fence);
+ r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
+ if (!r)
+ return true;
+ dma_fence_put(fence);
+ }
+
+ return false;
+}
+
+static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
+{
+ struct dma_buf *dmabuf;
+ struct dma_resv *resv;
+ __poll_t events;
+
+ dmabuf = file->private_data;
+ if (!dmabuf || !dmabuf->resv)
+ return EPOLLERR;
+
+ resv = dmabuf->resv;
+
+ poll_wait(file, &dmabuf->poll, poll);
+
+ events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);
+ if (!events)
+ return 0;
+
+ dma_resv_lock(resv, NULL);
+
+ if (events & EPOLLOUT) {
+ struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_out;
+
+ /* Check that callback isn't busy */
+ spin_lock_irq(&dmabuf->poll.lock);
+ if (dcb->active)
+ events &= ~EPOLLOUT;
+ else
+ dcb->active = EPOLLOUT;
+ spin_unlock_irq(&dmabuf->poll.lock);
+
+ if (events & EPOLLOUT) {
+ /* Paired with fput in dma_buf_poll_cb */
+ get_file(dmabuf->file);
+
+ if (!dma_buf_poll_add_cb(resv, true, dcb))
+ /* No callback queued, wake up any other waiters */
+ dma_buf_poll_cb(NULL, &dcb->cb);
+ else
+ events &= ~EPOLLOUT;
+ }
+ }
+
+ if (events & EPOLLIN) {
+ struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_in;
+
+ /* Check that callback isn't busy */
+ spin_lock_irq(&dmabuf->poll.lock);
+ if (dcb->active)
+ events &= ~EPOLLIN;
+ else
+ dcb->active = EPOLLIN;
+ spin_unlock_irq(&dmabuf->poll.lock);
+
+ if (events & EPOLLIN) {
+ /* Paired with fput in dma_buf_poll_cb */
+ get_file(dmabuf->file);
+
+ if (!dma_buf_poll_add_cb(resv, false, dcb))
+ /* No callback queued, wake up any other waiters */
+ dma_buf_poll_cb(NULL, &dcb->cb);
+ else
+ events &= ~EPOLLIN;
+ }
+ }
+
+ dma_resv_unlock(resv);
+ return events;
+}
+
+/**
+ * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
+ * It could support changing the name of the dma-buf if the same
+ * piece of memory is used for multiple purpose between different devices.
+ *
+ * @dmabuf: [in] dmabuf buffer that will be renamed.
+ * @buf: [in] A piece of userspace memory that contains the name of
+ * the dma-buf.
+ *
+ * Returns 0 on success. If the dma-buf buffer is already attached to
+ * devices, return -EBUSY.
+ *
+ */
+static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
+{
+ char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
+
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
+ spin_lock(&dmabuf->name_lock);
+ kfree(dmabuf->name);
+ dmabuf->name = name;
+ spin_unlock(&dmabuf->name_lock);
+
+ return 0;
+}
+
+#if IS_ENABLED(CONFIG_SYNC_FILE)
+static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
+ void __user *user_data)
+{
+ struct dma_buf_export_sync_file arg;
+ enum dma_resv_usage usage;
+ struct dma_fence *fence = NULL;
+ struct sync_file *sync_file;
+ int fd, ret;
+
+ if (copy_from_user(&arg, user_data, sizeof(arg)))
+ return -EFAULT;
+
+ if (arg.flags & ~DMA_BUF_SYNC_RW)
+ return -EINVAL;
+
+ if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
+ return -EINVAL;
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
+ usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE);
+ ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence);
+ if (ret)
+ goto err_put_fd;
+
+ if (!fence)
+ fence = dma_fence_get_stub();
+
+ sync_file = sync_file_create(fence);
+
+ dma_fence_put(fence);
+
+ if (!sync_file) {
+ ret = -ENOMEM;
+ goto err_put_fd;
+ }
+
+ arg.fd = fd;
+ if (copy_to_user(user_data, &arg, sizeof(arg))) {
+ ret = -EFAULT;
+ goto err_put_file;
+ }
+
+ fd_install(fd, sync_file->file);
+
+ return 0;
+
+err_put_file:
+ fput(sync_file->file);
+err_put_fd:
+ put_unused_fd(fd);
+ return ret;
+}
+
+static long dma_buf_import_sync_file(struct dma_buf *dmabuf,
+ const void __user *user_data)
+{
+ struct dma_buf_import_sync_file arg;
+ struct dma_fence *fence, *f;
+ enum dma_resv_usage usage;
+ struct dma_fence_unwrap iter;
+ unsigned int num_fences;
+ int ret = 0;
+
+ if (copy_from_user(&arg, user_data, sizeof(arg)))
+ return -EFAULT;
+
+ if (arg.flags & ~DMA_BUF_SYNC_RW)
+ return -EINVAL;
+
+ if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
+ return -EINVAL;
+
+ fence = sync_file_get_fence(arg.fd);
+ if (!fence)
+ return -EINVAL;
+
+ usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :
+ DMA_RESV_USAGE_READ;
+
+ num_fences = 0;
+ dma_fence_unwrap_for_each(f, &iter, fence)
+ ++num_fences;
+
+ if (num_fences > 0) {
+ dma_resv_lock(dmabuf->resv, NULL);
+
+ ret = dma_resv_reserve_fences(dmabuf->resv, num_fences);
+ if (!ret) {
+ dma_fence_unwrap_for_each(f, &iter, fence)
+ dma_resv_add_fence(dmabuf->resv, f, usage);
+ }
+
+ dma_resv_unlock(dmabuf->resv);
+ }
+
+ dma_fence_put(fence);
+
+ return ret;
+}
+#endif
+
+static long dma_buf_ioctl(struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct dma_buf *dmabuf;
+ struct dma_buf_sync sync;
+ enum dma_data_direction direction;
+ int ret;
+
+ dmabuf = file->private_data;
+
+ switch (cmd) {
+ case DMA_BUF_IOCTL_SYNC:
+ if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
+ return -EFAULT;
+
+ if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
+ return -EINVAL;
+
+ switch (sync.flags & DMA_BUF_SYNC_RW) {
+ case DMA_BUF_SYNC_READ:
+ direction = DMA_FROM_DEVICE;
+ break;
+ case DMA_BUF_SYNC_WRITE:
+ direction = DMA_TO_DEVICE;
+ break;
+ case DMA_BUF_SYNC_RW:
+ direction = DMA_BIDIRECTIONAL;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (sync.flags & DMA_BUF_SYNC_END)
+ ret = dma_buf_end_cpu_access(dmabuf, direction);
+ else
+ ret = dma_buf_begin_cpu_access(dmabuf, direction);
+
+ return ret;
+
+ case DMA_BUF_SET_NAME_A:
+ case DMA_BUF_SET_NAME_B:
+ return dma_buf_set_name(dmabuf, (const char __user *)arg);
+
+#if IS_ENABLED(CONFIG_SYNC_FILE)
+ case DMA_BUF_IOCTL_EXPORT_SYNC_FILE:
+ return dma_buf_export_sync_file(dmabuf, (void __user *)arg);
+ case DMA_BUF_IOCTL_IMPORT_SYNC_FILE:
+ return dma_buf_import_sync_file(dmabuf, (const void __user *)arg);
+#endif
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
+{
+ struct dma_buf *dmabuf = file->private_data;
+
+ seq_printf(m, "size:\t%zu\n", dmabuf->size);
+ /* Don't count the temporary reference taken inside procfs seq_show */
+ seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
+ seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
+ spin_lock(&dmabuf->name_lock);
+ if (dmabuf->name)
+ seq_printf(m, "name:\t%s\n", dmabuf->name);
+ spin_unlock(&dmabuf->name_lock);
+}
+
+static const struct file_operations dma_buf_fops = {
+ .release = dma_buf_file_release,
+ .mmap = dma_buf_mmap_internal,
+ .llseek = dma_buf_llseek,
+ .poll = dma_buf_poll,
+ .unlocked_ioctl = dma_buf_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+ .show_fdinfo = dma_buf_show_fdinfo,
+};
+
+/*
+ * is_dma_buf_file - Check if struct file* is associated with dma_buf
+ */
+static inline int is_dma_buf_file(struct file *file)
+{
+ return file->f_op == &dma_buf_fops;
+}
+
+static struct file *dma_buf_getfile(size_t size, int flags)
+{
+ static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);
+ struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
+ struct file *file;
+
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ inode->i_size = size;
+ inode_set_bytes(inode, size);
+
+ /*
+ * The ->i_ino acquired from get_next_ino() is not unique thus
+ * not suitable for using it as dentry name by dmabuf stats.
+ * Override ->i_ino with the unique and dmabuffs specific
+ * value.
+ */
+ inode->i_ino = atomic64_add_return(1, &dmabuf_inode);
+ flags &= O_ACCMODE | O_NONBLOCK;
+ file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",
+ flags, &dma_buf_fops);
+ if (IS_ERR(file))
+ goto err_alloc_file;
+
+ return file;
+
+err_alloc_file:
+ iput(inode);
+ return file;
+}
+
+/**
+ * DOC: dma buf device access
+ *
+ * For device DMA access to a shared DMA buffer the usual sequence of operations
+ * is fairly simple:
+ *
+ * 1. The exporter defines his exporter instance using
+ * DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private
+ * buffer object into a &dma_buf. It then exports that &dma_buf to userspace
+ * as a file descriptor by calling dma_buf_fd().
+ *
+ * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
+ * to share with: First the file descriptor is converted to a &dma_buf using
+ * dma_buf_get(). Then the buffer is attached to the device using
+ * dma_buf_attach().
+ *
+ * Up to this stage the exporter is still free to migrate or reallocate the
+ * backing storage.
+ *
+ * 3. Once the buffer is attached to all devices userspace can initiate DMA
+ * access to the shared buffer. In the kernel this is done by calling
+ * dma_buf_map_attachment() and dma_buf_unmap_attachment().
+ *
+ * 4. Once a driver is done with a shared buffer it needs to call
+ * dma_buf_detach() (after cleaning up any mappings) and then release the
+ * reference acquired with dma_buf_get() by calling dma_buf_put().
+ *
+ * For the detailed semantics exporters are expected to implement see
+ * &dma_buf_ops.
+ */
+
+/**
+ * dma_buf_export - Creates a new dma_buf, and associates an anon file
+ * with this buffer, so it can be exported.
+ * Also connect the allocator specific data and ops to the buffer.
+ * Additionally, provide a name string for exporter; useful in debugging.
+ *
+ * @exp_info: [in] holds all the export related information provided
+ * by the exporter. see &struct dma_buf_export_info
+ * for further details.
+ *
+ * Returns, on success, a newly created struct dma_buf object, which wraps the
+ * supplied private data and operations for struct dma_buf_ops. On either
+ * missing ops, or error in allocating struct dma_buf, will return negative
+ * error.
+ *
+ * For most cases the easiest way to create @exp_info is through the
+ * %DEFINE_DMA_BUF_EXPORT_INFO macro.
+ */
+struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
+{
+ struct dma_buf *dmabuf;
+ struct dma_resv *resv = exp_info->resv;
+ struct file *file;
+ size_t alloc_size = sizeof(struct dma_buf);
+ int ret;
+
+ if (WARN_ON(!exp_info->priv || !exp_info->ops
+ || !exp_info->ops->map_dma_buf
+ || !exp_info->ops->unmap_dma_buf
+ || !exp_info->ops->release))
+ return ERR_PTR(-EINVAL);
+
+ if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
+ (exp_info->ops->pin || exp_info->ops->unpin)))
+ return ERR_PTR(-EINVAL);
+
+ if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
+ return ERR_PTR(-EINVAL);
+
+ if (!try_module_get(exp_info->owner))
+ return ERR_PTR(-ENOENT);
+
+ file = dma_buf_getfile(exp_info->size, exp_info->flags);
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto err_module;
+ }
+
+ if (!exp_info->resv)
+ alloc_size += sizeof(struct dma_resv);
+ else
+ /* prevent &dma_buf[1] == dma_buf->resv */
+ alloc_size += 1;
+ dmabuf = kzalloc(alloc_size, GFP_KERNEL);
+ if (!dmabuf) {
+ ret = -ENOMEM;
+ goto err_file;
+ }
+
+ dmabuf->priv = exp_info->priv;
+ dmabuf->ops = exp_info->ops;
+ dmabuf->size = exp_info->size;
+ dmabuf->exp_name = exp_info->exp_name;
+ dmabuf->owner = exp_info->owner;
+ spin_lock_init(&dmabuf->name_lock);
+ init_waitqueue_head(&dmabuf->poll);
+ dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
+ dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
+ INIT_LIST_HEAD(&dmabuf->attachments);
+
+ if (!resv) {
+ dmabuf->resv = (struct dma_resv *)&dmabuf[1];
+ dma_resv_init(dmabuf->resv);
+ } else {
+ dmabuf->resv = resv;
+ }
+
+ ret = dma_buf_stats_setup(dmabuf, file);
+ if (ret)
+ goto err_dmabuf;
+
+ file->private_data = dmabuf;
+ file->f_path.dentry->d_fsdata = dmabuf;
+ dmabuf->file = file;
+
+ mutex_lock(&db_list.lock);
+ list_add(&dmabuf->list_node, &db_list.head);
+ mutex_unlock(&db_list.lock);
+
+ return dmabuf;
+
+err_dmabuf:
+ if (!resv)
+ dma_resv_fini(dmabuf->resv);
+ kfree(dmabuf);
+err_file:
+ fput(file);
+err_module:
+ module_put(exp_info->owner);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_export, DMA_BUF);
+
+/**
+ * dma_buf_fd - returns a file descriptor for the given struct dma_buf
+ * @dmabuf: [in] pointer to dma_buf for which fd is required.
+ * @flags: [in] flags to give to fd
+ *
+ * On success, returns an associated 'fd'. Else, returns error.
+ */
+int dma_buf_fd(struct dma_buf *dmabuf, int flags)
+{
+ int fd;
+
+ if (!dmabuf || !dmabuf->file)
+ return -EINVAL;
+
+ fd = get_unused_fd_flags(flags);
+ if (fd < 0)
+ return fd;
+
+ fd_install(fd, dmabuf->file);
+
+ return fd;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_fd, DMA_BUF);
+
+/**
+ * dma_buf_get - returns the struct dma_buf related to an fd
+ * @fd: [in] fd associated with the struct dma_buf to be returned
+ *
+ * On success, returns the struct dma_buf associated with an fd; uses
+ * file's refcounting done by fget to increase refcount. returns ERR_PTR
+ * otherwise.
+ */
+struct dma_buf *dma_buf_get(int fd)
+{
+ struct file *file;
+
+ file = fget(fd);
+
+ if (!file)
+ return ERR_PTR(-EBADF);
+
+ if (!is_dma_buf_file(file)) {
+ fput(file);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return file->private_data;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_get, DMA_BUF);
+
+/**
+ * dma_buf_put - decreases refcount of the buffer
+ * @dmabuf: [in] buffer to reduce refcount of
+ *
+ * Uses file's refcounting done implicitly by fput().
+ *
+ * If, as a result of this call, the refcount becomes 0, the 'release' file
+ * operation related to this fd is called. It calls &dma_buf_ops.release vfunc
+ * in turn, and frees the memory allocated for dmabuf when exported.
+ */
+void dma_buf_put(struct dma_buf *dmabuf)
+{
+ if (WARN_ON(!dmabuf || !dmabuf->file))
+ return;
+
+ fput(dmabuf->file);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_put, DMA_BUF);
+
+static void mangle_sg_table(struct sg_table *sg_table)
+{
+#ifdef CONFIG_DMABUF_DEBUG
+ int i;
+ struct scatterlist *sg;
+
+ /* To catch abuse of the underlying struct page by importers mix
+ * up the bits, but take care to preserve the low SG_ bits to
+ * not corrupt the sgt. The mixing is undone in __unmap_dma_buf
+ * before passing the sgt back to the exporter. */
+ for_each_sgtable_sg(sg_table, sg, i)
+ sg->page_link ^= ~0xffUL;
+#endif
+
+}
+static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,
+ enum dma_data_direction direction)
+{
+ struct sg_table *sg_table;
+ signed long ret;
+
+ sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+ if (IS_ERR_OR_NULL(sg_table))
+ return sg_table;
+
+ if (!dma_buf_attachment_is_dynamic(attach)) {
+ ret = dma_resv_wait_timeout(attach->dmabuf->resv,
+ DMA_RESV_USAGE_KERNEL, true,
+ MAX_SCHEDULE_TIMEOUT);
+ if (ret < 0) {
+ attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
+ direction);
+ return ERR_PTR(ret);
+ }
+ }
+
+ mangle_sg_table(sg_table);
+ return sg_table;
+}
+
+/**
+ * DOC: locking convention
+ *
+ * In order to avoid deadlock situations between dma-buf exports and importers,
+ * all dma-buf API users must follow the common dma-buf locking convention.
+ *
+ * Convention for importers
+ *
+ * 1. Importers must hold the dma-buf reservation lock when calling these
+ * functions:
+ *
+ * - dma_buf_pin()
+ * - dma_buf_unpin()
+ * - dma_buf_map_attachment()
+ * - dma_buf_unmap_attachment()
+ * - dma_buf_vmap()
+ * - dma_buf_vunmap()
+ *
+ * 2. Importers must not hold the dma-buf reservation lock when calling these
+ * functions:
+ *
+ * - dma_buf_attach()
+ * - dma_buf_dynamic_attach()
+ * - dma_buf_detach()
+ * - dma_buf_export()
+ * - dma_buf_fd()
+ * - dma_buf_get()
+ * - dma_buf_put()
+ * - dma_buf_mmap()
+ * - dma_buf_begin_cpu_access()
+ * - dma_buf_end_cpu_access()
+ * - dma_buf_map_attachment_unlocked()
+ * - dma_buf_unmap_attachment_unlocked()
+ * - dma_buf_vmap_unlocked()
+ * - dma_buf_vunmap_unlocked()
+ *
+ * Convention for exporters
+ *
+ * 1. These &dma_buf_ops callbacks are invoked with unlocked dma-buf
+ * reservation and exporter can take the lock:
+ *
+ * - &dma_buf_ops.attach()
+ * - &dma_buf_ops.detach()
+ * - &dma_buf_ops.release()
+ * - &dma_buf_ops.begin_cpu_access()
+ * - &dma_buf_ops.end_cpu_access()
+ * - &dma_buf_ops.mmap()
+ *
+ * 2. These &dma_buf_ops callbacks are invoked with locked dma-buf
+ * reservation and exporter can't take the lock:
+ *
+ * - &dma_buf_ops.pin()
+ * - &dma_buf_ops.unpin()
+ * - &dma_buf_ops.map_dma_buf()
+ * - &dma_buf_ops.unmap_dma_buf()
+ * - &dma_buf_ops.vmap()
+ * - &dma_buf_ops.vunmap()
+ *
+ * 3. Exporters must hold the dma-buf reservation lock when calling these
+ * functions:
+ *
+ * - dma_buf_move_notify()
+ */
+
+/**
+ * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list
+ * @dmabuf: [in] buffer to attach device to.
+ * @dev: [in] device to be attached.
+ * @importer_ops: [in] importer operations for the attachment
+ * @importer_priv: [in] importer private pointer for the attachment
+ *
+ * Returns struct dma_buf_attachment pointer for this attachment. Attachments
+ * must be cleaned up by calling dma_buf_detach().
+ *
+ * Optionally this calls &dma_buf_ops.attach to allow device-specific attach
+ * functionality.
+ *
+ * Returns:
+ *
+ * A pointer to newly created &dma_buf_attachment on success, or a negative
+ * error code wrapped into a pointer on failure.
+ *
+ * Note that this can fail if the backing storage of @dmabuf is in a place not
+ * accessible to @dev, and cannot be moved to a more suitable place. This is
+ * indicated with the error code -EBUSY.
+ */
+struct dma_buf_attachment *
+dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
+ const struct dma_buf_attach_ops *importer_ops,
+ void *importer_priv)
+{
+ struct dma_buf_attachment *attach;
+ int ret;
+
+ if (WARN_ON(!dmabuf || !dev))
+ return ERR_PTR(-EINVAL);
+
+ if (WARN_ON(importer_ops && !importer_ops->move_notify))
+ return ERR_PTR(-EINVAL);
+
+ attach = kzalloc(sizeof(*attach), GFP_KERNEL);
+ if (!attach)
+ return ERR_PTR(-ENOMEM);
+
+ attach->dev = dev;
+ attach->dmabuf = dmabuf;
+ if (importer_ops)
+ attach->peer2peer = importer_ops->allow_peer2peer;
+ attach->importer_ops = importer_ops;
+ attach->importer_priv = importer_priv;
+
+ if (dmabuf->ops->attach) {
+ ret = dmabuf->ops->attach(dmabuf, attach);
+ if (ret)
+ goto err_attach;
+ }
+ dma_resv_lock(dmabuf->resv, NULL);
+ list_add(&attach->node, &dmabuf->attachments);
+ dma_resv_unlock(dmabuf->resv);
+
+ /* When either the importer or the exporter can't handle dynamic
+ * mappings we cache the mapping here to avoid issues with the
+ * reservation object lock.
+ */
+ if (dma_buf_attachment_is_dynamic(attach) !=
+ dma_buf_is_dynamic(dmabuf)) {
+ struct sg_table *sgt;
+
+ dma_resv_lock(attach->dmabuf->resv, NULL);
+ if (dma_buf_is_dynamic(attach->dmabuf)) {
+ ret = dmabuf->ops->pin(attach);
+ if (ret)
+ goto err_unlock;
+ }
+
+ sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
+ if (!sgt)
+ sgt = ERR_PTR(-ENOMEM);
+ if (IS_ERR(sgt)) {
+ ret = PTR_ERR(sgt);
+ goto err_unpin;
+ }
+ dma_resv_unlock(attach->dmabuf->resv);
+ attach->sgt = sgt;
+ attach->dir = DMA_BIDIRECTIONAL;
+ }
+
+ return attach;
+
+err_attach:
+ kfree(attach);
+ return ERR_PTR(ret);
+
+err_unpin:
+ if (dma_buf_is_dynamic(attach->dmabuf))
+ dmabuf->ops->unpin(attach);
+
+err_unlock:
+ dma_resv_unlock(attach->dmabuf->resv);
+
+ dma_buf_detach(dmabuf, attach);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, DMA_BUF);
+
+/**
+ * dma_buf_attach - Wrapper for dma_buf_dynamic_attach
+ * @dmabuf: [in] buffer to attach device to.
+ * @dev: [in] device to be attached.
+ *
+ * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static
+ * mapping.
+ */
+struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
+ struct device *dev)
+{
+ return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_attach, DMA_BUF);
+
+static void __unmap_dma_buf(struct dma_buf_attachment *attach,
+ struct sg_table *sg_table,
+ enum dma_data_direction direction)
+{
+ /* uses XOR, hence this unmangles */
+ mangle_sg_table(sg_table);
+
+ attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
+}
+
+/**
+ * dma_buf_detach - Remove the given attachment from dmabuf's attachments list
+ * @dmabuf: [in] buffer to detach from.
+ * @attach: [in] attachment to be detached; is free'd after this call.
+ *
+ * Clean up a device attachment obtained by calling dma_buf_attach().
+ *
+ * Optionally this calls &dma_buf_ops.detach for device-specific detach.
+ */
+void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
+{
+ if (WARN_ON(!dmabuf || !attach || dmabuf != attach->dmabuf))
+ return;
+
+ dma_resv_lock(dmabuf->resv, NULL);
+
+ if (attach->sgt) {
+
+ __unmap_dma_buf(attach, attach->sgt, attach->dir);
+
+ if (dma_buf_is_dynamic(attach->dmabuf))
+ dmabuf->ops->unpin(attach);
+ }
+ list_del(&attach->node);
+
+ dma_resv_unlock(dmabuf->resv);
+
+ if (dmabuf->ops->detach)
+ dmabuf->ops->detach(dmabuf, attach);
+
+ kfree(attach);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_detach, DMA_BUF);
+
+/**
+ * dma_buf_pin - Lock down the DMA-buf
+ * @attach: [in] attachment which should be pinned
+ *
+ * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may
+ * call this, and only for limited use cases like scanout and not for temporary
+ * pin operations. It is not permitted to allow userspace to pin arbitrary
+ * amounts of buffers through this interface.
+ *
+ * Buffers must be unpinned by calling dma_buf_unpin().
+ *
+ * Returns:
+ * 0 on success, negative error code on failure.
+ */
+int dma_buf_pin(struct dma_buf_attachment *attach)
+{
+ struct dma_buf *dmabuf = attach->dmabuf;
+ int ret = 0;
+
+ WARN_ON(!dma_buf_attachment_is_dynamic(attach));
+
+ dma_resv_assert_held(dmabuf->resv);
+
+ if (dmabuf->ops->pin)
+ ret = dmabuf->ops->pin(attach);
+
+ return ret;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_pin, DMA_BUF);
+
+/**
+ * dma_buf_unpin - Unpin a DMA-buf
+ * @attach: [in] attachment which should be unpinned
+ *
+ * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move
+ * any mapping of @attach again and inform the importer through
+ * &dma_buf_attach_ops.move_notify.
+ */
+void dma_buf_unpin(struct dma_buf_attachment *attach)
+{
+ struct dma_buf *dmabuf = attach->dmabuf;
+
+ WARN_ON(!dma_buf_attachment_is_dynamic(attach));
+
+ dma_resv_assert_held(dmabuf->resv);
+
+ if (dmabuf->ops->unpin)
+ dmabuf->ops->unpin(attach);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, DMA_BUF);
+
+/**
+ * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
+ * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
+ * dma_buf_ops.
+ * @attach: [in] attachment whose scatterlist is to be returned
+ * @direction: [in] direction of DMA transfer
+ *
+ * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
+ * on error. May return -EINTR if it is interrupted by a signal.
+ *
+ * On success, the DMA addresses and lengths in the returned scatterlist are
+ * PAGE_SIZE aligned.
+ *
+ * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
+ * the underlying backing storage is pinned for as long as a mapping exists,
+ * therefore users/importers should not hold onto a mapping for undue amounts of
+ * time.
+ *
+ * Important: Dynamic importers must wait for the exclusive fence of the struct
+ * dma_resv attached to the DMA-BUF first.
+ */
+struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
+ enum dma_data_direction direction)
+{
+ struct sg_table *sg_table;
+ int r;
+
+ might_sleep();
+
+ if (WARN_ON(!attach || !attach->dmabuf))
+ return ERR_PTR(-EINVAL);
+
+ dma_resv_assert_held(attach->dmabuf->resv);
+
+ if (attach->sgt) {
+ /*
+ * Two mappings with different directions for the same
+ * attachment are not allowed.
+ */
+ if (attach->dir != direction &&
+ attach->dir != DMA_BIDIRECTIONAL)
+ return ERR_PTR(-EBUSY);
+
+ return attach->sgt;
+ }
+
+ if (dma_buf_is_dynamic(attach->dmabuf)) {
+ if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
+ r = attach->dmabuf->ops->pin(attach);
+ if (r)
+ return ERR_PTR(r);
+ }
+ }
+
+ sg_table = __map_dma_buf(attach, direction);
+ if (!sg_table)
+ sg_table = ERR_PTR(-ENOMEM);
+
+ if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&
+ !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
+ attach->dmabuf->ops->unpin(attach);
+
+ if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
+ attach->sgt = sg_table;
+ attach->dir = direction;
+ }
+
+#ifdef CONFIG_DMA_API_DEBUG
+ if (!IS_ERR(sg_table)) {
+ struct scatterlist *sg;
+ u64 addr;
+ int len;
+ int i;
+
+ for_each_sgtable_dma_sg(sg_table, sg, i) {
+ addr = sg_dma_address(sg);
+ len = sg_dma_len(sg);
+ if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {
+ pr_debug("%s: addr %llx or len %x is not page aligned!\n",
+ __func__, addr, len);
+ }
+ }
+ }
+#endif /* CONFIG_DMA_API_DEBUG */
+ return sg_table;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, DMA_BUF);
+
+/**
+ * dma_buf_map_attachment_unlocked - Returns the scatterlist table of the attachment;
+ * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
+ * dma_buf_ops.
+ * @attach: [in] attachment whose scatterlist is to be returned
+ * @direction: [in] direction of DMA transfer
+ *
+ * Unlocked variant of dma_buf_map_attachment().
+ */
+struct sg_table *
+dma_buf_map_attachment_unlocked(struct dma_buf_attachment *attach,
+ enum dma_data_direction direction)
+{
+ struct sg_table *sg_table;
+
+ might_sleep();
+
+ if (WARN_ON(!attach || !attach->dmabuf))
+ return ERR_PTR(-EINVAL);
+
+ dma_resv_lock(attach->dmabuf->resv, NULL);
+ sg_table = dma_buf_map_attachment(attach, direction);
+ dma_resv_unlock(attach->dmabuf->resv);
+
+ return sg_table;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment_unlocked, DMA_BUF);
+
+/**
+ * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
+ * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
+ * dma_buf_ops.
+ * @attach: [in] attachment to unmap buffer from
+ * @sg_table: [in] scatterlist info of the buffer to unmap
+ * @direction: [in] direction of DMA transfer
+ *
+ * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
+ */
+void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
+ struct sg_table *sg_table,
+ enum dma_data_direction direction)
+{
+ might_sleep();
+
+ if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
+ return;
+
+ dma_resv_assert_held(attach->dmabuf->resv);
+
+ if (attach->sgt == sg_table)
+ return;
+
+ __unmap_dma_buf(attach, sg_table, direction);
+
+ if (dma_buf_is_dynamic(attach->dmabuf) &&
+ !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
+ dma_buf_unpin(attach);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, DMA_BUF);
+
+/**
+ * dma_buf_unmap_attachment_unlocked - unmaps and decreases usecount of the buffer;might
+ * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
+ * dma_buf_ops.
+ * @attach: [in] attachment to unmap buffer from
+ * @sg_table: [in] scatterlist info of the buffer to unmap
+ * @direction: [in] direction of DMA transfer
+ *
+ * Unlocked variant of dma_buf_unmap_attachment().
+ */
+void dma_buf_unmap_attachment_unlocked(struct dma_buf_attachment *attach,
+ struct sg_table *sg_table,
+ enum dma_data_direction direction)
+{
+ might_sleep();
+
+ if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
+ return;
+
+ dma_resv_lock(attach->dmabuf->resv, NULL);
+ dma_buf_unmap_attachment(attach, sg_table, direction);
+ dma_resv_unlock(attach->dmabuf->resv);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment_unlocked, DMA_BUF);
+
+/**
+ * dma_buf_move_notify - notify attachments that DMA-buf is moving
+ *
+ * @dmabuf: [in] buffer which is moving
+ *
+ * Informs all attachments that they need to destroy and recreate all their
+ * mappings.
+ */
+void dma_buf_move_notify(struct dma_buf *dmabuf)
+{
+ struct dma_buf_attachment *attach;
+
+ dma_resv_assert_held(dmabuf->resv);
+
+ list_for_each_entry(attach, &dmabuf->attachments, node)
+ if (attach->importer_ops)
+ attach->importer_ops->move_notify(attach);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_move_notify, DMA_BUF);
+
+/**
+ * DOC: cpu access
+ *
+ * There are multiple reasons for supporting CPU access to a dma buffer object:
+ *
+ * - Fallback operations in the kernel, for example when a device is connected
+ * over USB and the kernel needs to shuffle the data around first before
+ * sending it away. Cache coherency is handled by bracketing any transactions
+ * with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
+ * access.
+ *
+ * Since for most kernel internal dma-buf accesses need the entire buffer, a
+ * vmap interface is introduced. Note that on very old 32-bit architectures
+ * vmalloc space might be limited and result in vmap calls failing.
+ *
+ * Interfaces::
+ *
+ * void \*dma_buf_vmap(struct dma_buf \*dmabuf, struct iosys_map \*map)
+ * void dma_buf_vunmap(struct dma_buf \*dmabuf, struct iosys_map \*map)
+ *
+ * The vmap call can fail if there is no vmap support in the exporter, or if
+ * it runs out of vmalloc space. Note that the dma-buf layer keeps a reference
+ * count for all vmap access and calls down into the exporter's vmap function
+ * only when no vmapping exists, and only unmaps it once. Protection against
+ * concurrent vmap/vunmap calls is provided by taking the &dma_buf.lock mutex.
+ *
+ * - For full compatibility on the importer side with existing userspace
+ * interfaces, which might already support mmap'ing buffers. This is needed in
+ * many processing pipelines (e.g. feeding a software rendered image into a
+ * hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION
+ * framework already supported this and for DMA buffer file descriptors to
+ * replace ION buffers mmap support was needed.
+ *
+ * There is no special interfaces, userspace simply calls mmap on the dma-buf
+ * fd. But like for CPU access there's a need to bracket the actual access,
+ * which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that
+ * DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must
+ * be restarted.
+ *
+ * Some systems might need some sort of cache coherency management e.g. when
+ * CPU and GPU domains are being accessed through dma-buf at the same time.
+ * To circumvent this problem there are begin/end coherency markers, that
+ * forward directly to existing dma-buf device drivers vfunc hooks. Userspace
+ * can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
+ * sequence would be used like following:
+ *
+ * - mmap dma-buf fd
+ * - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
+ * to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
+ * want (with the new data being consumed by say the GPU or the scanout
+ * device)
+ * - munmap once you don't need the buffer any more
+ *
+ * For correctness and optimal performance, it is always required to use
+ * SYNC_START and SYNC_END before and after, respectively, when accessing the
+ * mapped address. Userspace cannot rely on coherent access, even when there
+ * are systems where it just works without calling these ioctls.
+ *
+ * - And as a CPU fallback in userspace processing pipelines.
+ *
+ * Similar to the motivation for kernel cpu access it is again important that
+ * the userspace code of a given importing subsystem can use the same
+ * interfaces with a imported dma-buf buffer object as with a native buffer
+ * object. This is especially important for drm where the userspace part of
+ * contemporary OpenGL, X, and other drivers is huge, and reworking them to
+ * use a different way to mmap a buffer rather invasive.
+ *
+ * The assumption in the current dma-buf interfaces is that redirecting the
+ * initial mmap is all that's needed. A survey of some of the existing
+ * subsystems shows that no driver seems to do any nefarious thing like
+ * syncing up with outstanding asynchronous processing on the device or
+ * allocating special resources at fault time. So hopefully this is good
+ * enough, since adding interfaces to intercept pagefaults and allow pte
+ * shootdowns would increase the complexity quite a bit.
+ *
+ * Interface::
+ *
+ * int dma_buf_mmap(struct dma_buf \*, struct vm_area_struct \*,
+ * unsigned long);
+ *
+ * If the importing subsystem simply provides a special-purpose mmap call to
+ * set up a mapping in userspace, calling do_mmap with &dma_buf.file will
+ * equally achieve that for a dma-buf object.
+ */
+
+static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ bool write = (direction == DMA_BIDIRECTIONAL ||
+ direction == DMA_TO_DEVICE);
+ struct dma_resv *resv = dmabuf->resv;
+ long ret;
+
+ /* Wait on any implicit rendering fences */
+ ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),
+ true, MAX_SCHEDULE_TIMEOUT);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+/**
+ * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
+ * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
+ * preparations. Coherency is only guaranteed in the specified range for the
+ * specified access direction.
+ * @dmabuf: [in] buffer to prepare cpu access for.
+ * @direction: [in] direction of access.
+ *
+ * After the cpu access is complete the caller should call
+ * dma_buf_end_cpu_access(). Only when cpu access is bracketed by both calls is
+ * it guaranteed to be coherent with other DMA access.
+ *
+ * This function will also wait for any DMA transactions tracked through
+ * implicit synchronization in &dma_buf.resv. For DMA transactions with explicit
+ * synchronization this function will only ensure cache coherency, callers must
+ * ensure synchronization with such DMA transactions on their own.
+ *
+ * Can return negative error values, returns 0 on success.
+ */
+int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ int ret = 0;
+
+ if (WARN_ON(!dmabuf))
+ return -EINVAL;
+
+ might_lock(&dmabuf->resv->lock.base);
+
+ if (dmabuf->ops->begin_cpu_access)
+ ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
+
+ /* Ensure that all fences are waited upon - but we first allow
+ * the native handler the chance to do so more efficiently if it
+ * chooses. A double invocation here will be reasonably cheap no-op.
+ */
+ if (ret == 0)
+ ret = __dma_buf_begin_cpu_access(dmabuf, direction);
+
+ return ret;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_begin_cpu_access, DMA_BUF);
+
+/**
+ * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
+ * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
+ * actions. Coherency is only guaranteed in the specified range for the
+ * specified access direction.
+ * @dmabuf: [in] buffer to complete cpu access for.
+ * @direction: [in] direction of access.
+ *
+ * This terminates CPU access started with dma_buf_begin_cpu_access().
+ *
+ * Can return negative error values, returns 0 on success.
+ */
+int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ int ret = 0;
+
+ WARN_ON(!dmabuf);
+
+ might_lock(&dmabuf->resv->lock.base);
+
+ if (dmabuf->ops->end_cpu_access)
+ ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
+
+ return ret;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, DMA_BUF);
+
+
+/**
+ * dma_buf_mmap - Setup up a userspace mmap with the given vma
+ * @dmabuf: [in] buffer that should back the vma
+ * @vma: [in] vma for the mmap
+ * @pgoff: [in] offset in pages where this mmap should start within the
+ * dma-buf buffer.
+ *
+ * This function adjusts the passed in vma so that it points at the file of the
+ * dma_buf operation. It also adjusts the starting pgoff and does bounds
+ * checking on the size of the vma. Then it calls the exporters mmap function to
+ * set up the mapping.
+ *
+ * Can return negative error values, returns 0 on success.
+ */
+int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
+ unsigned long pgoff)
+{
+ if (WARN_ON(!dmabuf || !vma))
+ return -EINVAL;
+
+ /* check if buffer supports mmap */
+ if (!dmabuf->ops->mmap)
+ return -EINVAL;
+
+ /* check for offset overflow */
+ if (pgoff + vma_pages(vma) < pgoff)
+ return -EOVERFLOW;
+
+ /* check for overflowing the buffer's size */
+ if (pgoff + vma_pages(vma) >
+ dmabuf->size >> PAGE_SHIFT)
+ return -EINVAL;
+
+ /* readjust the vma */
+ vma_set_file(vma, dmabuf->file);
+ vma->vm_pgoff = pgoff;
+
+ return dmabuf->ops->mmap(dmabuf, vma);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
+
+/**
+ * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
+ * address space. Same restrictions as for vmap and friends apply.
+ * @dmabuf: [in] buffer to vmap
+ * @map: [out] returns the vmap pointer
+ *
+ * This call may fail due to lack of virtual mapping address space.
+ * These calls are optional in drivers. The intended use for them
+ * is for mapping objects linear in kernel space for high use objects.
+ *
+ * To ensure coherency users must call dma_buf_begin_cpu_access() and
+ * dma_buf_end_cpu_access() around any cpu access performed through this
+ * mapping.
+ *
+ * Returns 0 on success, or a negative errno code otherwise.
+ */
+int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
+{
+ struct iosys_map ptr;
+ int ret;
+
+ iosys_map_clear(map);
+
+ if (WARN_ON(!dmabuf))
+ return -EINVAL;
+
+ dma_resv_assert_held(dmabuf->resv);
+
+ if (!dmabuf->ops->vmap)
+ return -EINVAL;
+
+ if (dmabuf->vmapping_counter) {
+ dmabuf->vmapping_counter++;
+ BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
+ *map = dmabuf->vmap_ptr;
+ return 0;
+ }
+
+ BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
+
+ ret = dmabuf->ops->vmap(dmabuf, &ptr);
+ if (WARN_ON_ONCE(ret))
+ return ret;
+
+ dmabuf->vmap_ptr = ptr;
+ dmabuf->vmapping_counter = 1;
+
+ *map = dmabuf->vmap_ptr;
+
+ return 0;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
+
+/**
+ * dma_buf_vmap_unlocked - Create virtual mapping for the buffer object into kernel
+ * address space. Same restrictions as for vmap and friends apply.
+ * @dmabuf: [in] buffer to vmap
+ * @map: [out] returns the vmap pointer
+ *
+ * Unlocked version of dma_buf_vmap()
+ *
+ * Returns 0 on success, or a negative errno code otherwise.
+ */
+int dma_buf_vmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
+{
+ int ret;
+
+ iosys_map_clear(map);
+
+ if (WARN_ON(!dmabuf))
+ return -EINVAL;
+
+ dma_resv_lock(dmabuf->resv, NULL);
+ ret = dma_buf_vmap(dmabuf, map);
+ dma_resv_unlock(dmabuf->resv);
+
+ return ret;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_vmap_unlocked, DMA_BUF);
+
+/**
+ * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
+ * @dmabuf: [in] buffer to vunmap
+ * @map: [in] vmap pointer to vunmap
+ */
+void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
+{
+ if (WARN_ON(!dmabuf))
+ return;
+
+ dma_resv_assert_held(dmabuf->resv);
+
+ BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
+ BUG_ON(dmabuf->vmapping_counter == 0);
+ BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
+
+ if (--dmabuf->vmapping_counter == 0) {
+ if (dmabuf->ops->vunmap)
+ dmabuf->ops->vunmap(dmabuf, map);
+ iosys_map_clear(&dmabuf->vmap_ptr);
+ }
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
+
+/**
+ * dma_buf_vunmap_unlocked - Unmap a vmap obtained by dma_buf_vmap.
+ * @dmabuf: [in] buffer to vunmap
+ * @map: [in] vmap pointer to vunmap
+ */
+void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
+{
+ if (WARN_ON(!dmabuf))
+ return;
+
+ dma_resv_lock(dmabuf->resv, NULL);
+ dma_buf_vunmap(dmabuf, map);
+ dma_resv_unlock(dmabuf->resv);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, DMA_BUF);
+
+#ifdef CONFIG_DEBUG_FS
+static int dma_buf_debug_show(struct seq_file *s, void *unused)
+{
+ struct dma_buf *buf_obj;
+ struct dma_buf_attachment *attach_obj;
+ int count = 0, attach_count;
+ size_t size = 0;
+ int ret;
+
+ ret = mutex_lock_interruptible(&db_list.lock);
+
+ if (ret)
+ return ret;
+
+ seq_puts(s, "\nDma-buf Objects:\n");
+ seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",
+ "size", "flags", "mode", "count", "ino");
+
+ list_for_each_entry(buf_obj, &db_list.head, list_node) {
+
+ ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
+ if (ret)
+ goto error_unlock;
+
+
+ spin_lock(&buf_obj->name_lock);
+ seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
+ buf_obj->size,
+ buf_obj->file->f_flags, buf_obj->file->f_mode,
+ file_count(buf_obj->file),
+ buf_obj->exp_name,
+ file_inode(buf_obj->file)->i_ino,
+ buf_obj->name ?: "<none>");
+ spin_unlock(&buf_obj->name_lock);
+
+ dma_resv_describe(buf_obj->resv, s);
+
+ seq_puts(s, "\tAttached Devices:\n");
+ attach_count = 0;
+
+ list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
+ seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
+ attach_count++;
+ }
+ dma_resv_unlock(buf_obj->resv);
+
+ seq_printf(s, "Total %d devices attached\n\n",
+ attach_count);
+
+ count++;
+ size += buf_obj->size;
+ }
+
+ seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
+
+ mutex_unlock(&db_list.lock);
+ return 0;
+
+error_unlock:
+ mutex_unlock(&db_list.lock);
+ return ret;
+}
+
+DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
+
+static struct dentry *dma_buf_debugfs_dir;
+
+static int dma_buf_init_debugfs(void)
+{
+ struct dentry *d;
+ int err = 0;
+
+ d = debugfs_create_dir("dma_buf", NULL);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+
+ dma_buf_debugfs_dir = d;
+
+ d = debugfs_create_file("bufinfo", S_IRUGO, dma_buf_debugfs_dir,
+ NULL, &dma_buf_debug_fops);
+ if (IS_ERR(d)) {
+ pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
+ debugfs_remove_recursive(dma_buf_debugfs_dir);
+ dma_buf_debugfs_dir = NULL;
+ err = PTR_ERR(d);
+ }
+
+ return err;
+}
+
+static void dma_buf_uninit_debugfs(void)
+{
+ debugfs_remove_recursive(dma_buf_debugfs_dir);
+}
+#else
+static inline int dma_buf_init_debugfs(void)
+{
+ return 0;
+}
+static inline void dma_buf_uninit_debugfs(void)
+{
+}
+#endif
+
+static int __init dma_buf_init(void)
+{
+ int ret;
+
+ ret = dma_buf_init_sysfs_statistics();
+ if (ret)
+ return ret;
+
+ dma_buf_mnt = kern_mount(&dma_buf_fs_type);
+ if (IS_ERR(dma_buf_mnt))
+ return PTR_ERR(dma_buf_mnt);
+
+ mutex_init(&db_list.lock);
+ INIT_LIST_HEAD(&db_list.head);
+ dma_buf_init_debugfs();
+ return 0;
+}
+subsys_initcall(dma_buf_init);
+
+static void __exit dma_buf_deinit(void)
+{
+ dma_buf_uninit_debugfs();
+ kern_unmount(dma_buf_mnt);
+ dma_buf_uninit_sysfs_statistics();
+}
+__exitcall(dma_buf_deinit);