1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * drivers/dma-buf/sync_file.c
  4 *
  5 * Copyright (C) 2012 Google, Inc.
  6 */
  7
  8#include <linux/dma-fence-unwrap.h>
  9#include <linux/export.h>
 10#include <linux/file.h>
 11#include <linux/fs.h>
 12#include <linux/kernel.h>
 13#include <linux/poll.h>
 14#include <linux/sched.h>
 15#include <linux/slab.h>
 16#include <linux/uaccess.h>
 17#include <linux/anon_inodes.h>
 18#include <linux/sync_file.h>
 19#include <uapi/linux/sync_file.h>
 20
 21static const struct file_operations sync_file_fops;
 22
 23static struct sync_file *sync_file_alloc(void)
 24{
 25	struct sync_file *sync_file;
 26
 27	sync_file = kzalloc(sizeof(*sync_file), GFP_KERNEL);
 28	if (!sync_file)
 29		return NULL;
 30
 31	sync_file->file = anon_inode_getfile("sync_file", &sync_file_fops,
 32					     sync_file, 0);
 33	if (IS_ERR(sync_file->file))
 34		goto err;
 35
 36	init_waitqueue_head(&sync_file->wq);
 37
 38	INIT_LIST_HEAD(&sync_file->cb.node);
 39
 40	return sync_file;
 41
 42err:
 43	kfree(sync_file);
 44	return NULL;
 45}
 46
 47static void fence_check_cb_func(struct dma_fence *f, struct dma_fence_cb *cb)
 48{
 49	struct sync_file *sync_file;
 50
 51	sync_file = container_of(cb, struct sync_file, cb);
 52
 53	wake_up_all(&sync_file->wq);
 54}
 55
 56/**
 57 * sync_file_create() - creates a sync file
 58 * @fence:	fence to add to the sync_fence
 59 *
 60 * Creates a sync_file containg @fence. This function acquires and additional
 61 * reference of @fence for the newly-created &sync_file, if it succeeds. The
 62 * sync_file can be released with fput(sync_file->file). Returns the
 63 * sync_file or NULL in case of error.
 64 */
 65struct sync_file *sync_file_create(struct dma_fence *fence)
 66{
 67	struct sync_file *sync_file;
 68
 69	sync_file = sync_file_alloc();
 70	if (!sync_file)
 71		return NULL;
 72
 73	sync_file->fence = dma_fence_get(fence);
 74
 75	return sync_file;
 76}
 77EXPORT_SYMBOL(sync_file_create);
 78
 79static struct sync_file *sync_file_fdget(int fd)
 80{
 81	struct file *file = fget(fd);
 82
 83	if (!file)
 84		return NULL;
 85
 86	if (file->f_op != &sync_file_fops)
 87		goto err;
 88
 89	return file->private_data;
 90
 91err:
 92	fput(file);
 93	return NULL;
 94}
 95
 96/**
 97 * sync_file_get_fence - get the fence related to the sync_file fd
 98 * @fd:		sync_file fd to get the fence from
 99 *
100 * Ensures @fd references a valid sync_file and returns a fence that
101 * represents all fence in the sync_file. On error NULL is returned.
102 */
103struct dma_fence *sync_file_get_fence(int fd)
104{
105	struct sync_file *sync_file;
106	struct dma_fence *fence;
107
108	sync_file = sync_file_fdget(fd);
109	if (!sync_file)
110		return NULL;
111
112	fence = dma_fence_get(sync_file->fence);
113	fput(sync_file->file);
114
115	return fence;
116}
117EXPORT_SYMBOL(sync_file_get_fence);
118
119/**
120 * sync_file_get_name - get the name of the sync_file
121 * @sync_file:		sync_file to get the fence from
122 * @buf:		destination buffer to copy sync_file name into
123 * @len:		available size of destination buffer.
124 *
125 * Each sync_file may have a name assigned either by the user (when merging
126 * sync_files together) or created from the fence it contains. In the latter
127 * case construction of the name is deferred until use, and so requires
128 * sync_file_get_name().
129 *
130 * Returns: a string representing the name.
131 */
132char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
133{
134	if (sync_file->user_name[0]) {
135		strscpy(buf, sync_file->user_name, len);
136	} else {
137		struct dma_fence *fence = sync_file->fence;
138
139		snprintf(buf, len, "%s-%s%llu-%lld",
140			 fence->ops->get_driver_name(fence),
141			 fence->ops->get_timeline_name(fence),
142			 fence->context,
143			 fence->seqno);
144	}
145
146	return buf;
147}
148
149/**
150 * sync_file_merge() - merge two sync_files
151 * @name:	name of new fence
152 * @a:		sync_file a
153 * @b:		sync_file b
154 *
155 * Creates a new sync_file which contains copies of all the fences in both
156 * @a and @b.  @a and @b remain valid, independent sync_file. Returns the
157 * new merged sync_file or NULL in case of error.
158 */
159static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
160					 struct sync_file *b)
161{
162	struct sync_file *sync_file;
163	struct dma_fence *fence;
164
165	sync_file = sync_file_alloc();
166	if (!sync_file)
167		return NULL;
168
169	fence = dma_fence_unwrap_merge(a->fence, b->fence);
170	if (!fence) {
171		fput(sync_file->file);
172		return NULL;
173	}
174	sync_file->fence = fence;
175	strscpy(sync_file->user_name, name, sizeof(sync_file->user_name));
176	return sync_file;
177}
178
179static int sync_file_release(struct inode *inode, struct file *file)
180{
181	struct sync_file *sync_file = file->private_data;
182
183	if (test_bit(POLL_ENABLED, &sync_file->flags))
184		dma_fence_remove_callback(sync_file->fence, &sync_file->cb);
185	dma_fence_put(sync_file->fence);
186	kfree(sync_file);
187
188	return 0;
189}
190
191static __poll_t sync_file_poll(struct file *file, poll_table *wait)
192{
193	struct sync_file *sync_file = file->private_data;
194
195	poll_wait(file, &sync_file->wq, wait);
196
197	if (list_empty(&sync_file->cb.node) &&
198	    !test_and_set_bit(POLL_ENABLED, &sync_file->flags)) {
199		if (dma_fence_add_callback(sync_file->fence, &sync_file->cb,
200					   fence_check_cb_func) < 0)
201			wake_up_all(&sync_file->wq);
202	}
203
204	return dma_fence_is_signaled(sync_file->fence) ? EPOLLIN : 0;
205}
206
207static long sync_file_ioctl_merge(struct sync_file *sync_file,
208				  unsigned long arg)
209{
210	int fd = get_unused_fd_flags(O_CLOEXEC);
211	int err;
212	struct sync_file *fence2, *fence3;
213	struct sync_merge_data data;
214
215	if (fd < 0)
216		return fd;
217
218	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
219		err = -EFAULT;
220		goto err_put_fd;
221	}
222
223	if (data.flags || data.pad) {
224		err = -EINVAL;
225		goto err_put_fd;
226	}
227
228	fence2 = sync_file_fdget(data.fd2);
229	if (!fence2) {
230		err = -ENOENT;
231		goto err_put_fd;
232	}
233
234	data.name[sizeof(data.name) - 1] = '\0';
235	fence3 = sync_file_merge(data.name, sync_file, fence2);
236	if (!fence3) {
237		err = -ENOMEM;
238		goto err_put_fence2;
239	}
240
241	data.fence = fd;
242	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
243		err = -EFAULT;
244		goto err_put_fence3;
245	}
246
247	fd_install(fd, fence3->file);
248	fput(fence2->file);
249	return 0;
250
251err_put_fence3:
252	fput(fence3->file);
253
254err_put_fence2:
255	fput(fence2->file);
256
257err_put_fd:
258	put_unused_fd(fd);
259	return err;
260}
261
262static int sync_fill_fence_info(struct dma_fence *fence,
263				 struct sync_fence_info *info)
264{
265	strscpy(info->obj_name, fence->ops->get_timeline_name(fence),
266		sizeof(info->obj_name));
267	strscpy(info->driver_name, fence->ops->get_driver_name(fence),
268		sizeof(info->driver_name));
269
270	info->status = dma_fence_get_status(fence);
271	while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
272	       !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
273		cpu_relax();
274	info->timestamp_ns =
275		test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?
276		ktime_to_ns(fence->timestamp) :
277		ktime_set(0, 0);
278
279	return info->status;
280}
281
282static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
283				       unsigned long arg)
284{
285	struct sync_fence_info *fence_info = NULL;
286	struct dma_fence_unwrap iter;
287	struct sync_file_info info;
288	unsigned int num_fences;
289	struct dma_fence *fence;
290	int ret;
291	__u32 size;
292
293	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
294		return -EFAULT;
295
296	if (info.flags || info.pad)
297		return -EINVAL;
298
299	num_fences = 0;
300	dma_fence_unwrap_for_each(fence, &iter, sync_file->fence)
301		++num_fences;
302
303	/*
304	 * Passing num_fences = 0 means that userspace doesn't want to
305	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
306	 * sync_fence_info and return the actual number of fences on
307	 * info->num_fences.
308	 */
309	if (!info.num_fences) {
310		info.status = dma_fence_get_status(sync_file->fence);
311		goto no_fences;
312	} else {
313		info.status = 1;
314	}
315
316	if (info.num_fences < num_fences)
317		return -EINVAL;
318
319	size = num_fences * sizeof(*fence_info);
320	fence_info = kzalloc(size, GFP_KERNEL);
321	if (!fence_info)
322		return -ENOMEM;
323
324	num_fences = 0;
325	dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) {
326		int status;
327
328		status = sync_fill_fence_info(fence, &fence_info[num_fences++]);
329		info.status = info.status <= 0 ? info.status : status;
330	}
331
332	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,
333			 size)) {
334		ret = -EFAULT;
335		goto out;
336	}
337
338no_fences:
339	sync_file_get_name(sync_file, info.name, sizeof(info.name));
340	info.num_fences = num_fences;
341
342	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
343		ret = -EFAULT;
344	else
345		ret = 0;
346
347out:
348	kfree(fence_info);
349
350	return ret;
351}
352
353static long sync_file_ioctl(struct file *file, unsigned int cmd,
354			    unsigned long arg)
355{
356	struct sync_file *sync_file = file->private_data;
357
358	switch (cmd) {
359	case SYNC_IOC_MERGE:
360		return sync_file_ioctl_merge(sync_file, arg);
361
362	case SYNC_IOC_FILE_INFO:
363		return sync_file_ioctl_fence_info(sync_file, arg);
364
365	default:
366		return -ENOTTY;
367	}
368}
369
370static const struct file_operations sync_file_fops = {
371	.release = sync_file_release,
372	.poll = sync_file_poll,
373	.unlocked_ioctl = sync_file_ioctl,
374	.compat_ioctl = compat_ptr_ioctl,
375};