![Christian König](/assets/img/avatar_default.png)
To allow a smooth transition from pinning buffer objects to dynamic invalidation we first start to cache the sg_table for an attachment. v2: keep closer to the DRM implementation Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.kernel.org/patch/10943053/
1182 lines
33 KiB
C
1182 lines
33 KiB
C
/*
|
|
* 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.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 as published by
|
|
* the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
* more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along with
|
|
* this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/dma-buf.h>
|
|
#include <linux/dma-fence.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/poll.h>
|
|
#include <linux/reservation.h>
|
|
#include <linux/mm.h>
|
|
|
|
#include <uapi/linux/dma-buf.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 int dma_buf_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct dma_buf *dmabuf;
|
|
|
|
if (!is_dma_buf_file(file))
|
|
return -EINVAL;
|
|
|
|
dmabuf = file->private_data;
|
|
|
|
BUG_ON(dmabuf->vmapping_counter);
|
|
|
|
/*
|
|
* Any fences that a dma-buf poll can wait on should be signaled
|
|
* before releasing dma-buf. This is the responsibility of each
|
|
* driver that uses the reservation objects.
|
|
*
|
|
* If you hit this BUG() it means someone dropped their ref to the
|
|
* dma-buf while still having pending operation to the buffer.
|
|
*/
|
|
BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);
|
|
|
|
dmabuf->ops->release(dmabuf);
|
|
|
|
mutex_lock(&db_list.lock);
|
|
list_del(&dmabuf->list_node);
|
|
mutex_unlock(&db_list.lock);
|
|
|
|
if (dmabuf->resv == (struct reservation_object *)&dmabuf[1])
|
|
reservation_object_fini(dmabuf->resv);
|
|
|
|
module_put(dmabuf->owner);
|
|
kfree(dmabuf);
|
|
return 0;
|
|
}
|
|
|
|
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: fence polling
|
|
*
|
|
* To support cross-device and cross-driver synchronization of buffer access
|
|
* implicit fences (represented internally in the kernel with &struct fence) can
|
|
* be attached to a &dma_buf. The glue for that and a few related things are
|
|
* provided in the &reservation_object 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.
|
|
*/
|
|
|
|
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;
|
|
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);
|
|
}
|
|
|
|
static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
|
|
{
|
|
struct dma_buf *dmabuf;
|
|
struct reservation_object *resv;
|
|
struct reservation_object_list *fobj;
|
|
struct dma_fence *fence_excl;
|
|
__poll_t events;
|
|
unsigned shared_count, seq;
|
|
|
|
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;
|
|
|
|
retry:
|
|
seq = read_seqcount_begin(&resv->seq);
|
|
rcu_read_lock();
|
|
|
|
fobj = rcu_dereference(resv->fence);
|
|
if (fobj)
|
|
shared_count = fobj->shared_count;
|
|
else
|
|
shared_count = 0;
|
|
fence_excl = rcu_dereference(resv->fence_excl);
|
|
if (read_seqcount_retry(&resv->seq, seq)) {
|
|
rcu_read_unlock();
|
|
goto retry;
|
|
}
|
|
|
|
if (fence_excl && (!(events & EPOLLOUT) || shared_count == 0)) {
|
|
struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl;
|
|
__poll_t pevents = EPOLLIN;
|
|
|
|
if (shared_count == 0)
|
|
pevents |= EPOLLOUT;
|
|
|
|
spin_lock_irq(&dmabuf->poll.lock);
|
|
if (dcb->active) {
|
|
dcb->active |= pevents;
|
|
events &= ~pevents;
|
|
} else
|
|
dcb->active = pevents;
|
|
spin_unlock_irq(&dmabuf->poll.lock);
|
|
|
|
if (events & pevents) {
|
|
if (!dma_fence_get_rcu(fence_excl)) {
|
|
/* force a recheck */
|
|
events &= ~pevents;
|
|
dma_buf_poll_cb(NULL, &dcb->cb);
|
|
} else if (!dma_fence_add_callback(fence_excl, &dcb->cb,
|
|
dma_buf_poll_cb)) {
|
|
events &= ~pevents;
|
|
dma_fence_put(fence_excl);
|
|
} else {
|
|
/*
|
|
* No callback queued, wake up any additional
|
|
* waiters.
|
|
*/
|
|
dma_fence_put(fence_excl);
|
|
dma_buf_poll_cb(NULL, &dcb->cb);
|
|
}
|
|
}
|
|
}
|
|
|
|
if ((events & EPOLLOUT) && shared_count > 0) {
|
|
struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared;
|
|
int i;
|
|
|
|
/* Only queue a new callback if no event has fired yet */
|
|
spin_lock_irq(&dmabuf->poll.lock);
|
|
if (dcb->active)
|
|
events &= ~EPOLLOUT;
|
|
else
|
|
dcb->active = EPOLLOUT;
|
|
spin_unlock_irq(&dmabuf->poll.lock);
|
|
|
|
if (!(events & EPOLLOUT))
|
|
goto out;
|
|
|
|
for (i = 0; i < shared_count; ++i) {
|
|
struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
|
|
|
|
if (!dma_fence_get_rcu(fence)) {
|
|
/*
|
|
* fence refcount dropped to zero, this means
|
|
* that fobj has been freed
|
|
*
|
|
* call dma_buf_poll_cb and force a recheck!
|
|
*/
|
|
events &= ~EPOLLOUT;
|
|
dma_buf_poll_cb(NULL, &dcb->cb);
|
|
break;
|
|
}
|
|
if (!dma_fence_add_callback(fence, &dcb->cb,
|
|
dma_buf_poll_cb)) {
|
|
dma_fence_put(fence);
|
|
events &= ~EPOLLOUT;
|
|
break;
|
|
}
|
|
dma_fence_put(fence);
|
|
}
|
|
|
|
/* No callback queued, wake up any additional waiters. */
|
|
if (i == shared_count)
|
|
dma_buf_poll_cb(NULL, &dcb->cb);
|
|
}
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return events;
|
|
}
|
|
|
|
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;
|
|
default:
|
|
return -ENOTTY;
|
|
}
|
|
}
|
|
|
|
static const struct file_operations dma_buf_fops = {
|
|
.release = dma_buf_release,
|
|
.mmap = dma_buf_mmap_internal,
|
|
.llseek = dma_buf_llseek,
|
|
.poll = dma_buf_poll,
|
|
.unlocked_ioctl = dma_buf_ioctl,
|
|
#ifdef CONFIG_COMPAT
|
|
.compat_ioctl = dma_buf_ioctl,
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/**
|
|
* 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 filedescriptor 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 dma_buf object, which wraps the
|
|
* supplied private data and operations for 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 reservation_object *resv = exp_info->resv;
|
|
struct file *file;
|
|
size_t alloc_size = sizeof(struct dma_buf);
|
|
int ret;
|
|
|
|
if (!exp_info->resv)
|
|
alloc_size += sizeof(struct reservation_object);
|
|
else
|
|
/* prevent &dma_buf[1] == dma_buf->resv */
|
|
alloc_size += 1;
|
|
|
|
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 (!try_module_get(exp_info->owner))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
dmabuf = kzalloc(alloc_size, GFP_KERNEL);
|
|
if (!dmabuf) {
|
|
ret = -ENOMEM;
|
|
goto err_module;
|
|
}
|
|
|
|
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;
|
|
init_waitqueue_head(&dmabuf->poll);
|
|
dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
|
|
dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;
|
|
|
|
if (!resv) {
|
|
resv = (struct reservation_object *)&dmabuf[1];
|
|
reservation_object_init(resv);
|
|
}
|
|
dmabuf->resv = resv;
|
|
|
|
file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
|
|
exp_info->flags);
|
|
if (IS_ERR(file)) {
|
|
ret = PTR_ERR(file);
|
|
goto err_dmabuf;
|
|
}
|
|
|
|
file->f_mode |= FMODE_LSEEK;
|
|
dmabuf->file = file;
|
|
|
|
mutex_init(&dmabuf->lock);
|
|
INIT_LIST_HEAD(&dmabuf->attachments);
|
|
|
|
mutex_lock(&db_list.lock);
|
|
list_add(&dmabuf->list_node, &db_list.head);
|
|
mutex_unlock(&db_list.lock);
|
|
|
|
return dmabuf;
|
|
|
|
err_dmabuf:
|
|
kfree(dmabuf);
|
|
err_module:
|
|
module_put(exp_info->owner);
|
|
return ERR_PTR(ret);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_export);
|
|
|
|
/**
|
|
* dma_buf_fd - returns a file descriptor for the given 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_GPL(dma_buf_fd);
|
|
|
|
/**
|
|
* dma_buf_get - returns the dma_buf structure related to an fd
|
|
* @fd: [in] fd associated with the dma_buf to be returned
|
|
*
|
|
* On success, returns the dma_buf structure 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_GPL(dma_buf_get);
|
|
|
|
/**
|
|
* 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_GPL(dma_buf_put);
|
|
|
|
/**
|
|
* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
|
|
* calls attach() of dma_buf_ops to allow device-specific attach functionality
|
|
* @dmabuf: [in] buffer to attach device to.
|
|
* @dev: [in] device to be attached.
|
|
*
|
|
* Returns struct dma_buf_attachment pointer for this attachment. Attachments
|
|
* must be cleaned up by calling dma_buf_detach().
|
|
*
|
|
* 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_attach(struct dma_buf *dmabuf,
|
|
struct device *dev)
|
|
{
|
|
struct dma_buf_attachment *attach;
|
|
int ret;
|
|
|
|
if (WARN_ON(!dmabuf || !dev))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
attach = kzalloc(sizeof(*attach), GFP_KERNEL);
|
|
if (!attach)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
attach->dev = dev;
|
|
attach->dmabuf = dmabuf;
|
|
|
|
mutex_lock(&dmabuf->lock);
|
|
|
|
if (dmabuf->ops->attach) {
|
|
ret = dmabuf->ops->attach(dmabuf, attach);
|
|
if (ret)
|
|
goto err_attach;
|
|
}
|
|
list_add(&attach->node, &dmabuf->attachments);
|
|
|
|
mutex_unlock(&dmabuf->lock);
|
|
|
|
return attach;
|
|
|
|
err_attach:
|
|
kfree(attach);
|
|
mutex_unlock(&dmabuf->lock);
|
|
return ERR_PTR(ret);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_attach);
|
|
|
|
/**
|
|
* dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
|
|
* optionally calls detach() of dma_buf_ops for device-specific detach
|
|
* @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().
|
|
*/
|
|
void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
|
|
{
|
|
if (WARN_ON(!dmabuf || !attach))
|
|
return;
|
|
|
|
if (attach->sgt)
|
|
dmabuf->ops->unmap_dma_buf(attach, attach->sgt, attach->dir);
|
|
|
|
mutex_lock(&dmabuf->lock);
|
|
list_del(&attach->node);
|
|
if (dmabuf->ops->detach)
|
|
dmabuf->ops->detach(dmabuf, attach);
|
|
|
|
mutex_unlock(&dmabuf->lock);
|
|
kfree(attach);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_detach);
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* 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.
|
|
*/
|
|
struct sg_table *dma_buf_map_attachment(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);
|
|
|
|
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;
|
|
}
|
|
|
|
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
|
|
if (!sg_table)
|
|
sg_table = ERR_PTR(-ENOMEM);
|
|
|
|
if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
|
|
attach->sgt = sg_table;
|
|
attach->dir = direction;
|
|
}
|
|
|
|
return sg_table;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
|
|
|
|
/**
|
|
* 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;
|
|
|
|
if (attach->sgt == sg_table)
|
|
return;
|
|
|
|
attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
|
|
|
|
/**
|
|
* DOC: cpu access
|
|
*
|
|
* There are mutliple 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 braketing any transactions
|
|
* with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
|
|
* access.
|
|
*
|
|
* To support dma_buf objects residing in highmem cpu access is page-based
|
|
* using an api similar to kmap. Accessing a dma_buf is done in aligned chunks
|
|
* of PAGE_SIZE size. Before accessing a chunk it needs to be mapped, which
|
|
* returns a pointer in kernel virtual address space. Afterwards the chunk
|
|
* needs to be unmapped again. There is no limit on how often a given chunk
|
|
* can be mapped and unmapped, i.e. the importer does not need to call
|
|
* begin_cpu_access again before mapping the same chunk again.
|
|
*
|
|
* Interfaces::
|
|
* void \*dma_buf_kmap(struct dma_buf \*, unsigned long);
|
|
* void dma_buf_kunmap(struct dma_buf \*, unsigned long, void \*);
|
|
*
|
|
* Implementing the functions is optional for exporters and for importers all
|
|
* the restrictions of using kmap apply.
|
|
*
|
|
* dma_buf kmap calls outside of the range specified in begin_cpu_access are
|
|
* undefined. If the range is not PAGE_SIZE aligned, kmap needs to succeed on
|
|
* the partial chunks at the beginning and end but may return stale or bogus
|
|
* data outside of the range (in these partial chunks).
|
|
*
|
|
* For some cases the overhead of kmap can be too high, a vmap interface
|
|
* is introduced. This interface should be used very carefully, as vmalloc
|
|
* space is a limited resources on many architectures.
|
|
*
|
|
* Interfaces::
|
|
* void \*dma_buf_vmap(struct dma_buf \*dmabuf)
|
|
* void dma_buf_vunmap(struct dma_buf \*dmabuf, void \*vaddr)
|
|
*
|
|
* The vmap call can fail if there is no vmap support in the exporter, or if
|
|
* it runs out of vmalloc space. Fallback to kmap should be implemented. 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 braket 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 reservation_object *resv = dmabuf->resv;
|
|
long ret;
|
|
|
|
/* Wait on any implicit rendering fences */
|
|
ret = reservation_object_wait_timeout_rcu(resv, 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] length of range for cpu access.
|
|
*
|
|
* After the cpu access is complete the caller should call
|
|
* dma_buf_end_cpu_access(). Only when cpu access is braketed by both calls is
|
|
* it guaranteed to be coherent with other DMA access.
|
|
*
|
|
* 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;
|
|
|
|
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_GPL(dma_buf_begin_cpu_access);
|
|
|
|
/**
|
|
* 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] length of range for cpu 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);
|
|
|
|
if (dmabuf->ops->end_cpu_access)
|
|
ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
|
|
|
|
/**
|
|
* dma_buf_kmap - Map a page of the buffer object into kernel address space. The
|
|
* same restrictions as for kmap and friends apply.
|
|
* @dmabuf: [in] buffer to map page from.
|
|
* @page_num: [in] page in PAGE_SIZE units to map.
|
|
*
|
|
* This call must always succeed, any necessary preparations that might fail
|
|
* need to be done in begin_cpu_access.
|
|
*/
|
|
void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
|
|
{
|
|
WARN_ON(!dmabuf);
|
|
|
|
if (!dmabuf->ops->map)
|
|
return NULL;
|
|
return dmabuf->ops->map(dmabuf, page_num);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_kmap);
|
|
|
|
/**
|
|
* dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
|
|
* @dmabuf: [in] buffer to unmap page from.
|
|
* @page_num: [in] page in PAGE_SIZE units to unmap.
|
|
* @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
|
|
*
|
|
* This call must always succeed.
|
|
*/
|
|
void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
|
|
void *vaddr)
|
|
{
|
|
WARN_ON(!dmabuf);
|
|
|
|
if (dmabuf->ops->unmap)
|
|
dmabuf->ops->unmap(dmabuf, page_num, vaddr);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_kunmap);
|
|
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
struct file *oldfile;
|
|
int ret;
|
|
|
|
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 */
|
|
get_file(dmabuf->file);
|
|
oldfile = vma->vm_file;
|
|
vma->vm_file = dmabuf->file;
|
|
vma->vm_pgoff = pgoff;
|
|
|
|
ret = dmabuf->ops->mmap(dmabuf, vma);
|
|
if (ret) {
|
|
/* restore old parameters on failure */
|
|
vma->vm_file = oldfile;
|
|
fput(dmabuf->file);
|
|
} else {
|
|
if (oldfile)
|
|
fput(oldfile);
|
|
}
|
|
return ret;
|
|
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_mmap);
|
|
|
|
/**
|
|
* 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
|
|
*
|
|
* 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.
|
|
* Please attempt to use kmap/kunmap before thinking about these interfaces.
|
|
*
|
|
* Returns NULL on error.
|
|
*/
|
|
void *dma_buf_vmap(struct dma_buf *dmabuf)
|
|
{
|
|
void *ptr;
|
|
|
|
if (WARN_ON(!dmabuf))
|
|
return NULL;
|
|
|
|
if (!dmabuf->ops->vmap)
|
|
return NULL;
|
|
|
|
mutex_lock(&dmabuf->lock);
|
|
if (dmabuf->vmapping_counter) {
|
|
dmabuf->vmapping_counter++;
|
|
BUG_ON(!dmabuf->vmap_ptr);
|
|
ptr = dmabuf->vmap_ptr;
|
|
goto out_unlock;
|
|
}
|
|
|
|
BUG_ON(dmabuf->vmap_ptr);
|
|
|
|
ptr = dmabuf->ops->vmap(dmabuf);
|
|
if (WARN_ON_ONCE(IS_ERR(ptr)))
|
|
ptr = NULL;
|
|
if (!ptr)
|
|
goto out_unlock;
|
|
|
|
dmabuf->vmap_ptr = ptr;
|
|
dmabuf->vmapping_counter = 1;
|
|
|
|
out_unlock:
|
|
mutex_unlock(&dmabuf->lock);
|
|
return ptr;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_vmap);
|
|
|
|
/**
|
|
* dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
|
|
* @dmabuf: [in] buffer to vunmap
|
|
* @vaddr: [in] vmap to vunmap
|
|
*/
|
|
void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
|
|
{
|
|
if (WARN_ON(!dmabuf))
|
|
return;
|
|
|
|
BUG_ON(!dmabuf->vmap_ptr);
|
|
BUG_ON(dmabuf->vmapping_counter == 0);
|
|
BUG_ON(dmabuf->vmap_ptr != vaddr);
|
|
|
|
mutex_lock(&dmabuf->lock);
|
|
if (--dmabuf->vmapping_counter == 0) {
|
|
if (dmabuf->ops->vunmap)
|
|
dmabuf->ops->vunmap(dmabuf, vaddr);
|
|
dmabuf->vmap_ptr = NULL;
|
|
}
|
|
mutex_unlock(&dmabuf->lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dma_buf_vunmap);
|
|
|
|
#ifdef CONFIG_DEBUG_FS
|
|
static int dma_buf_debug_show(struct seq_file *s, void *unused)
|
|
{
|
|
int ret;
|
|
struct dma_buf *buf_obj;
|
|
struct dma_buf_attachment *attach_obj;
|
|
struct reservation_object *robj;
|
|
struct reservation_object_list *fobj;
|
|
struct dma_fence *fence;
|
|
unsigned seq;
|
|
int count = 0, attach_count, shared_count, i;
|
|
size_t size = 0;
|
|
|
|
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\n",
|
|
"size", "flags", "mode", "count");
|
|
|
|
list_for_each_entry(buf_obj, &db_list.head, list_node) {
|
|
ret = mutex_lock_interruptible(&buf_obj->lock);
|
|
|
|
if (ret) {
|
|
seq_puts(s,
|
|
"\tERROR locking buffer object: skipping\n");
|
|
continue;
|
|
}
|
|
|
|
seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\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);
|
|
|
|
robj = buf_obj->resv;
|
|
while (true) {
|
|
seq = read_seqcount_begin(&robj->seq);
|
|
rcu_read_lock();
|
|
fobj = rcu_dereference(robj->fence);
|
|
shared_count = fobj ? fobj->shared_count : 0;
|
|
fence = rcu_dereference(robj->fence_excl);
|
|
if (!read_seqcount_retry(&robj->seq, seq))
|
|
break;
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
if (fence)
|
|
seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",
|
|
fence->ops->get_driver_name(fence),
|
|
fence->ops->get_timeline_name(fence),
|
|
dma_fence_is_signaled(fence) ? "" : "un");
|
|
for (i = 0; i < shared_count; i++) {
|
|
fence = rcu_dereference(fobj->shared[i]);
|
|
if (!dma_fence_get_rcu(fence))
|
|
continue;
|
|
seq_printf(s, "\tShared fence: %s %s %ssignalled\n",
|
|
fence->ops->get_driver_name(fence),
|
|
fence->ops->get_timeline_name(fence),
|
|
dma_fence_is_signaled(fence) ? "" : "un");
|
|
dma_fence_put(fence);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
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++;
|
|
}
|
|
|
|
seq_printf(s, "Total %d devices attached\n\n",
|
|
attach_count);
|
|
|
|
count++;
|
|
size += buf_obj->size;
|
|
mutex_unlock(&buf_obj->lock);
|
|
}
|
|
|
|
seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
|
|
|
|
mutex_unlock(&db_list.lock);
|
|
return 0;
|
|
}
|
|
|
|
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)
|
|
{
|
|
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();
|
|
}
|
|
__exitcall(dma_buf_deinit);
|