Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * Framework for buffer objects that can be shared across devices/subsystems.
4 : *
5 : * Copyright(C) 2011 Linaro Limited. All rights reserved.
6 : * Author: Sumit Semwal <sumit.semwal@ti.com>
7 : *
8 : * Many thanks to linaro-mm-sig list, and specially
9 : * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
10 : * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
11 : * refining of this idea.
12 : */
13 :
14 : #include <linux/fs.h>
15 : #include <linux/slab.h>
16 : #include <linux/dma-buf.h>
17 : #include <linux/dma-fence.h>
18 : #include <linux/dma-fence-unwrap.h>
19 : #include <linux/anon_inodes.h>
20 : #include <linux/export.h>
21 : #include <linux/debugfs.h>
22 : #include <linux/module.h>
23 : #include <linux/seq_file.h>
24 : #include <linux/sync_file.h>
25 : #include <linux/poll.h>
26 : #include <linux/dma-resv.h>
27 : #include <linux/mm.h>
28 : #include <linux/mount.h>
29 : #include <linux/pseudo_fs.h>
30 :
31 : #include <uapi/linux/dma-buf.h>
32 : #include <uapi/linux/magic.h>
33 :
34 : #include "dma-buf-sysfs-stats.h"
35 :
36 : static inline int is_dma_buf_file(struct file *);
37 :
38 : struct dma_buf_list {
39 : struct list_head head;
40 : struct mutex lock;
41 : };
42 :
43 : static struct dma_buf_list db_list;
44 :
45 0 : static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
46 : {
47 : struct dma_buf *dmabuf;
48 : char name[DMA_BUF_NAME_LEN];
49 0 : size_t ret = 0;
50 :
51 0 : dmabuf = dentry->d_fsdata;
52 0 : spin_lock(&dmabuf->name_lock);
53 0 : if (dmabuf->name)
54 0 : ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
55 0 : spin_unlock(&dmabuf->name_lock);
56 :
57 0 : return dynamic_dname(buffer, buflen, "/%s:%s",
58 : dentry->d_name.name, ret > 0 ? name : "");
59 : }
60 :
61 0 : static void dma_buf_release(struct dentry *dentry)
62 : {
63 : struct dma_buf *dmabuf;
64 :
65 0 : dmabuf = dentry->d_fsdata;
66 0 : if (unlikely(!dmabuf))
67 : return;
68 :
69 0 : BUG_ON(dmabuf->vmapping_counter);
70 :
71 : /*
72 : * If you hit this BUG() it could mean:
73 : * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else
74 : * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback
75 : */
76 0 : BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
77 :
78 0 : dma_buf_stats_teardown(dmabuf);
79 0 : dmabuf->ops->release(dmabuf);
80 :
81 0 : if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
82 0 : dma_resv_fini(dmabuf->resv);
83 :
84 0 : WARN_ON(!list_empty(&dmabuf->attachments));
85 0 : module_put(dmabuf->owner);
86 0 : kfree(dmabuf->name);
87 0 : kfree(dmabuf);
88 : }
89 :
90 0 : static int dma_buf_file_release(struct inode *inode, struct file *file)
91 : {
92 : struct dma_buf *dmabuf;
93 :
94 0 : if (!is_dma_buf_file(file))
95 : return -EINVAL;
96 :
97 0 : dmabuf = file->private_data;
98 0 : if (dmabuf) {
99 0 : mutex_lock(&db_list.lock);
100 0 : list_del(&dmabuf->list_node);
101 0 : mutex_unlock(&db_list.lock);
102 : }
103 :
104 : return 0;
105 : }
106 :
107 : static const struct dentry_operations dma_buf_dentry_ops = {
108 : .d_dname = dmabuffs_dname,
109 : .d_release = dma_buf_release,
110 : };
111 :
112 : static struct vfsmount *dma_buf_mnt;
113 :
114 1 : static int dma_buf_fs_init_context(struct fs_context *fc)
115 : {
116 : struct pseudo_fs_context *ctx;
117 :
118 1 : ctx = init_pseudo(fc, DMA_BUF_MAGIC);
119 1 : if (!ctx)
120 : return -ENOMEM;
121 1 : ctx->dops = &dma_buf_dentry_ops;
122 1 : return 0;
123 : }
124 :
125 : static struct file_system_type dma_buf_fs_type = {
126 : .name = "dmabuf",
127 : .init_fs_context = dma_buf_fs_init_context,
128 : .kill_sb = kill_anon_super,
129 : };
130 :
131 0 : static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
132 : {
133 : struct dma_buf *dmabuf;
134 :
135 0 : if (!is_dma_buf_file(file))
136 : return -EINVAL;
137 :
138 0 : dmabuf = file->private_data;
139 :
140 : /* check if buffer supports mmap */
141 0 : if (!dmabuf->ops->mmap)
142 : return -EINVAL;
143 :
144 : /* check for overflowing the buffer's size */
145 0 : if (vma->vm_pgoff + vma_pages(vma) >
146 0 : dmabuf->size >> PAGE_SHIFT)
147 : return -EINVAL;
148 :
149 0 : return dmabuf->ops->mmap(dmabuf, vma);
150 : }
151 :
152 0 : static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
153 : {
154 : struct dma_buf *dmabuf;
155 : loff_t base;
156 :
157 0 : if (!is_dma_buf_file(file))
158 : return -EBADF;
159 :
160 0 : dmabuf = file->private_data;
161 :
162 : /* only support discovering the end of the buffer,
163 : but also allow SEEK_SET to maintain the idiomatic
164 : SEEK_END(0), SEEK_CUR(0) pattern */
165 0 : if (whence == SEEK_END)
166 0 : base = dmabuf->size;
167 0 : else if (whence == SEEK_SET)
168 : base = 0;
169 : else
170 : return -EINVAL;
171 :
172 0 : if (offset != 0)
173 : return -EINVAL;
174 :
175 0 : return base + offset;
176 : }
177 :
178 : /**
179 : * DOC: implicit fence polling
180 : *
181 : * To support cross-device and cross-driver synchronization of buffer access
182 : * implicit fences (represented internally in the kernel with &struct dma_fence)
183 : * can be attached to a &dma_buf. The glue for that and a few related things are
184 : * provided in the &dma_resv structure.
185 : *
186 : * Userspace can query the state of these implicitly tracked fences using poll()
187 : * and related system calls:
188 : *
189 : * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the
190 : * most recent write or exclusive fence.
191 : *
192 : * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of
193 : * all attached fences, shared and exclusive ones.
194 : *
195 : * Note that this only signals the completion of the respective fences, i.e. the
196 : * DMA transfers are complete. Cache flushing and any other necessary
197 : * preparations before CPU access can begin still need to happen.
198 : *
199 : * As an alternative to poll(), the set of fences on DMA buffer can be
200 : * exported as a &sync_file using &dma_buf_sync_file_export.
201 : */
202 :
203 0 : static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
204 : {
205 0 : struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
206 0 : struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);
207 : unsigned long flags;
208 :
209 0 : spin_lock_irqsave(&dcb->poll->lock, flags);
210 0 : wake_up_locked_poll(dcb->poll, dcb->active);
211 0 : dcb->active = 0;
212 0 : spin_unlock_irqrestore(&dcb->poll->lock, flags);
213 0 : dma_fence_put(fence);
214 : /* Paired with get_file in dma_buf_poll */
215 0 : fput(dmabuf->file);
216 0 : }
217 :
218 0 : static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
219 : struct dma_buf_poll_cb_t *dcb)
220 : {
221 : struct dma_resv_iter cursor;
222 : struct dma_fence *fence;
223 : int r;
224 :
225 0 : dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),
226 : fence) {
227 0 : dma_fence_get(fence);
228 0 : r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
229 0 : if (!r)
230 : return true;
231 0 : dma_fence_put(fence);
232 : }
233 :
234 : return false;
235 : }
236 :
237 0 : static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
238 : {
239 : struct dma_buf *dmabuf;
240 : struct dma_resv *resv;
241 : __poll_t events;
242 :
243 0 : dmabuf = file->private_data;
244 0 : if (!dmabuf || !dmabuf->resv)
245 : return EPOLLERR;
246 :
247 0 : resv = dmabuf->resv;
248 :
249 0 : poll_wait(file, &dmabuf->poll, poll);
250 :
251 0 : events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);
252 0 : if (!events)
253 : return 0;
254 :
255 0 : dma_resv_lock(resv, NULL);
256 :
257 0 : if (events & EPOLLOUT) {
258 0 : struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_out;
259 :
260 : /* Check that callback isn't busy */
261 0 : spin_lock_irq(&dmabuf->poll.lock);
262 0 : if (dcb->active)
263 0 : events &= ~EPOLLOUT;
264 : else
265 0 : dcb->active = EPOLLOUT;
266 0 : spin_unlock_irq(&dmabuf->poll.lock);
267 :
268 0 : if (events & EPOLLOUT) {
269 : /* Paired with fput in dma_buf_poll_cb */
270 0 : get_file(dmabuf->file);
271 :
272 0 : if (!dma_buf_poll_add_cb(resv, true, dcb))
273 : /* No callback queued, wake up any other waiters */
274 0 : dma_buf_poll_cb(NULL, &dcb->cb);
275 : else
276 0 : events &= ~EPOLLOUT;
277 : }
278 : }
279 :
280 0 : if (events & EPOLLIN) {
281 0 : struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_in;
282 :
283 : /* Check that callback isn't busy */
284 0 : spin_lock_irq(&dmabuf->poll.lock);
285 0 : if (dcb->active)
286 0 : events &= ~EPOLLIN;
287 : else
288 0 : dcb->active = EPOLLIN;
289 0 : spin_unlock_irq(&dmabuf->poll.lock);
290 :
291 0 : if (events & EPOLLIN) {
292 : /* Paired with fput in dma_buf_poll_cb */
293 0 : get_file(dmabuf->file);
294 :
295 0 : if (!dma_buf_poll_add_cb(resv, false, dcb))
296 : /* No callback queued, wake up any other waiters */
297 0 : dma_buf_poll_cb(NULL, &dcb->cb);
298 : else
299 0 : events &= ~EPOLLIN;
300 : }
301 : }
302 :
303 0 : dma_resv_unlock(resv);
304 0 : return events;
305 : }
306 :
307 : /**
308 : * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
309 : * It could support changing the name of the dma-buf if the same
310 : * piece of memory is used for multiple purpose between different devices.
311 : *
312 : * @dmabuf: [in] dmabuf buffer that will be renamed.
313 : * @buf: [in] A piece of userspace memory that contains the name of
314 : * the dma-buf.
315 : *
316 : * Returns 0 on success. If the dma-buf buffer is already attached to
317 : * devices, return -EBUSY.
318 : *
319 : */
320 0 : static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
321 : {
322 0 : char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
323 :
324 0 : if (IS_ERR(name))
325 0 : return PTR_ERR(name);
326 :
327 0 : spin_lock(&dmabuf->name_lock);
328 0 : kfree(dmabuf->name);
329 0 : dmabuf->name = name;
330 0 : spin_unlock(&dmabuf->name_lock);
331 :
332 : return 0;
333 : }
334 :
335 : #if IS_ENABLED(CONFIG_SYNC_FILE)
336 0 : static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
337 : void __user *user_data)
338 : {
339 : struct dma_buf_export_sync_file arg;
340 : enum dma_resv_usage usage;
341 0 : struct dma_fence *fence = NULL;
342 : struct sync_file *sync_file;
343 : int fd, ret;
344 :
345 0 : if (copy_from_user(&arg, user_data, sizeof(arg)))
346 : return -EFAULT;
347 :
348 0 : if (arg.flags & ~DMA_BUF_SYNC_RW)
349 : return -EINVAL;
350 :
351 0 : if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
352 : return -EINVAL;
353 :
354 0 : fd = get_unused_fd_flags(O_CLOEXEC);
355 0 : if (fd < 0)
356 0 : return fd;
357 :
358 0 : usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE);
359 0 : ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence);
360 0 : if (ret)
361 : goto err_put_fd;
362 :
363 0 : if (!fence)
364 0 : fence = dma_fence_get_stub();
365 :
366 0 : sync_file = sync_file_create(fence);
367 :
368 0 : dma_fence_put(fence);
369 :
370 0 : if (!sync_file) {
371 : ret = -ENOMEM;
372 : goto err_put_fd;
373 : }
374 :
375 0 : arg.fd = fd;
376 0 : if (copy_to_user(user_data, &arg, sizeof(arg))) {
377 0 : ret = -EFAULT;
378 : goto err_put_file;
379 : }
380 :
381 0 : fd_install(fd, sync_file->file);
382 :
383 : return 0;
384 :
385 : err_put_file:
386 0 : fput(sync_file->file);
387 : err_put_fd:
388 0 : put_unused_fd(fd);
389 0 : return ret;
390 : }
391 :
392 0 : static long dma_buf_import_sync_file(struct dma_buf *dmabuf,
393 : const void __user *user_data)
394 : {
395 : struct dma_buf_import_sync_file arg;
396 : struct dma_fence *fence, *f;
397 : enum dma_resv_usage usage;
398 : struct dma_fence_unwrap iter;
399 : unsigned int num_fences;
400 0 : int ret = 0;
401 :
402 0 : if (copy_from_user(&arg, user_data, sizeof(arg)))
403 : return -EFAULT;
404 :
405 0 : if (arg.flags & ~DMA_BUF_SYNC_RW)
406 : return -EINVAL;
407 :
408 0 : if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
409 : return -EINVAL;
410 :
411 0 : fence = sync_file_get_fence(arg.fd);
412 0 : if (!fence)
413 : return -EINVAL;
414 :
415 0 : usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :
416 : DMA_RESV_USAGE_READ;
417 :
418 0 : num_fences = 0;
419 0 : dma_fence_unwrap_for_each(f, &iter, fence)
420 0 : ++num_fences;
421 :
422 0 : if (num_fences > 0) {
423 0 : dma_resv_lock(dmabuf->resv, NULL);
424 :
425 0 : ret = dma_resv_reserve_fences(dmabuf->resv, num_fences);
426 0 : if (!ret) {
427 0 : dma_fence_unwrap_for_each(f, &iter, fence)
428 0 : dma_resv_add_fence(dmabuf->resv, f, usage);
429 : }
430 :
431 0 : dma_resv_unlock(dmabuf->resv);
432 : }
433 :
434 0 : dma_fence_put(fence);
435 :
436 0 : return ret;
437 : }
438 : #endif
439 :
440 0 : static long dma_buf_ioctl(struct file *file,
441 : unsigned int cmd, unsigned long arg)
442 : {
443 : struct dma_buf *dmabuf;
444 : struct dma_buf_sync sync;
445 : enum dma_data_direction direction;
446 : int ret;
447 :
448 0 : dmabuf = file->private_data;
449 :
450 0 : switch (cmd) {
451 : case DMA_BUF_IOCTL_SYNC:
452 0 : if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
453 : return -EFAULT;
454 :
455 0 : if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
456 : return -EINVAL;
457 :
458 0 : switch (sync.flags & DMA_BUF_SYNC_RW) {
459 : case DMA_BUF_SYNC_READ:
460 : direction = DMA_FROM_DEVICE;
461 : break;
462 : case DMA_BUF_SYNC_WRITE:
463 0 : direction = DMA_TO_DEVICE;
464 0 : break;
465 : case DMA_BUF_SYNC_RW:
466 0 : direction = DMA_BIDIRECTIONAL;
467 0 : break;
468 : default:
469 : return -EINVAL;
470 : }
471 :
472 0 : if (sync.flags & DMA_BUF_SYNC_END)
473 0 : ret = dma_buf_end_cpu_access(dmabuf, direction);
474 : else
475 0 : ret = dma_buf_begin_cpu_access(dmabuf, direction);
476 :
477 0 : return ret;
478 :
479 : case DMA_BUF_SET_NAME_A:
480 : case DMA_BUF_SET_NAME_B:
481 0 : return dma_buf_set_name(dmabuf, (const char __user *)arg);
482 :
483 : #if IS_ENABLED(CONFIG_SYNC_FILE)
484 : case DMA_BUF_IOCTL_EXPORT_SYNC_FILE:
485 0 : return dma_buf_export_sync_file(dmabuf, (void __user *)arg);
486 : case DMA_BUF_IOCTL_IMPORT_SYNC_FILE:
487 0 : return dma_buf_import_sync_file(dmabuf, (const void __user *)arg);
488 : #endif
489 :
490 : default:
491 : return -ENOTTY;
492 : }
493 : }
494 :
495 0 : static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
496 : {
497 0 : struct dma_buf *dmabuf = file->private_data;
498 :
499 0 : seq_printf(m, "size:\t%zu\n", dmabuf->size);
500 : /* Don't count the temporary reference taken inside procfs seq_show */
501 0 : seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
502 0 : seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
503 0 : spin_lock(&dmabuf->name_lock);
504 0 : if (dmabuf->name)
505 0 : seq_printf(m, "name:\t%s\n", dmabuf->name);
506 0 : spin_unlock(&dmabuf->name_lock);
507 0 : }
508 :
509 : static const struct file_operations dma_buf_fops = {
510 : .release = dma_buf_file_release,
511 : .mmap = dma_buf_mmap_internal,
512 : .llseek = dma_buf_llseek,
513 : .poll = dma_buf_poll,
514 : .unlocked_ioctl = dma_buf_ioctl,
515 : .compat_ioctl = compat_ptr_ioctl,
516 : .show_fdinfo = dma_buf_show_fdinfo,
517 : };
518 :
519 : /*
520 : * is_dma_buf_file - Check if struct file* is associated with dma_buf
521 : */
522 : static inline int is_dma_buf_file(struct file *file)
523 : {
524 : return file->f_op == &dma_buf_fops;
525 : }
526 :
527 0 : static struct file *dma_buf_getfile(size_t size, int flags)
528 : {
529 : static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);
530 0 : struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
531 : struct file *file;
532 :
533 0 : if (IS_ERR(inode))
534 : return ERR_CAST(inode);
535 :
536 0 : inode->i_size = size;
537 0 : inode_set_bytes(inode, size);
538 :
539 : /*
540 : * The ->i_ino acquired from get_next_ino() is not unique thus
541 : * not suitable for using it as dentry name by dmabuf stats.
542 : * Override ->i_ino with the unique and dmabuffs specific
543 : * value.
544 : */
545 0 : inode->i_ino = atomic64_add_return(1, &dmabuf_inode);
546 0 : flags &= O_ACCMODE | O_NONBLOCK;
547 0 : file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",
548 : flags, &dma_buf_fops);
549 0 : if (IS_ERR(file))
550 : goto err_alloc_file;
551 :
552 : return file;
553 :
554 : err_alloc_file:
555 0 : iput(inode);
556 0 : return file;
557 : }
558 :
559 : /**
560 : * DOC: dma buf device access
561 : *
562 : * For device DMA access to a shared DMA buffer the usual sequence of operations
563 : * is fairly simple:
564 : *
565 : * 1. The exporter defines his exporter instance using
566 : * DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private
567 : * buffer object into a &dma_buf. It then exports that &dma_buf to userspace
568 : * as a file descriptor by calling dma_buf_fd().
569 : *
570 : * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
571 : * to share with: First the file descriptor is converted to a &dma_buf using
572 : * dma_buf_get(). Then the buffer is attached to the device using
573 : * dma_buf_attach().
574 : *
575 : * Up to this stage the exporter is still free to migrate or reallocate the
576 : * backing storage.
577 : *
578 : * 3. Once the buffer is attached to all devices userspace can initiate DMA
579 : * access to the shared buffer. In the kernel this is done by calling
580 : * dma_buf_map_attachment() and dma_buf_unmap_attachment().
581 : *
582 : * 4. Once a driver is done with a shared buffer it needs to call
583 : * dma_buf_detach() (after cleaning up any mappings) and then release the
584 : * reference acquired with dma_buf_get() by calling dma_buf_put().
585 : *
586 : * For the detailed semantics exporters are expected to implement see
587 : * &dma_buf_ops.
588 : */
589 :
590 : /**
591 : * dma_buf_export - Creates a new dma_buf, and associates an anon file
592 : * with this buffer, so it can be exported.
593 : * Also connect the allocator specific data and ops to the buffer.
594 : * Additionally, provide a name string for exporter; useful in debugging.
595 : *
596 : * @exp_info: [in] holds all the export related information provided
597 : * by the exporter. see &struct dma_buf_export_info
598 : * for further details.
599 : *
600 : * Returns, on success, a newly created struct dma_buf object, which wraps the
601 : * supplied private data and operations for struct dma_buf_ops. On either
602 : * missing ops, or error in allocating struct dma_buf, will return negative
603 : * error.
604 : *
605 : * For most cases the easiest way to create @exp_info is through the
606 : * %DEFINE_DMA_BUF_EXPORT_INFO macro.
607 : */
608 0 : struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
609 : {
610 : struct dma_buf *dmabuf;
611 0 : struct dma_resv *resv = exp_info->resv;
612 : struct file *file;
613 0 : size_t alloc_size = sizeof(struct dma_buf);
614 : int ret;
615 :
616 0 : if (WARN_ON(!exp_info->priv || !exp_info->ops
617 : || !exp_info->ops->map_dma_buf
618 : || !exp_info->ops->unmap_dma_buf
619 : || !exp_info->ops->release))
620 : return ERR_PTR(-EINVAL);
621 :
622 0 : if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
623 : (exp_info->ops->pin || exp_info->ops->unpin)))
624 : return ERR_PTR(-EINVAL);
625 :
626 0 : if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
627 : return ERR_PTR(-EINVAL);
628 :
629 0 : if (!try_module_get(exp_info->owner))
630 : return ERR_PTR(-ENOENT);
631 :
632 0 : file = dma_buf_getfile(exp_info->size, exp_info->flags);
633 0 : if (IS_ERR(file)) {
634 0 : ret = PTR_ERR(file);
635 0 : goto err_module;
636 : }
637 :
638 0 : if (!exp_info->resv)
639 : alloc_size += sizeof(struct dma_resv);
640 : else
641 : /* prevent &dma_buf[1] == dma_buf->resv */
642 0 : alloc_size += 1;
643 0 : dmabuf = kzalloc(alloc_size, GFP_KERNEL);
644 0 : if (!dmabuf) {
645 0 : ret = -ENOMEM;
646 : goto err_file;
647 : }
648 :
649 0 : dmabuf->priv = exp_info->priv;
650 0 : dmabuf->ops = exp_info->ops;
651 0 : dmabuf->size = exp_info->size;
652 0 : dmabuf->exp_name = exp_info->exp_name;
653 0 : dmabuf->owner = exp_info->owner;
654 0 : spin_lock_init(&dmabuf->name_lock);
655 0 : init_waitqueue_head(&dmabuf->poll);
656 0 : dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
657 0 : dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
658 0 : INIT_LIST_HEAD(&dmabuf->attachments);
659 :
660 0 : if (!resv) {
661 0 : dmabuf->resv = (struct dma_resv *)&dmabuf[1];
662 0 : dma_resv_init(dmabuf->resv);
663 : } else {
664 0 : dmabuf->resv = resv;
665 : }
666 :
667 0 : ret = dma_buf_stats_setup(dmabuf, file);
668 : if (ret)
669 : goto err_dmabuf;
670 :
671 0 : file->private_data = dmabuf;
672 0 : file->f_path.dentry->d_fsdata = dmabuf;
673 0 : dmabuf->file = file;
674 :
675 0 : mutex_lock(&db_list.lock);
676 0 : list_add(&dmabuf->list_node, &db_list.head);
677 0 : mutex_unlock(&db_list.lock);
678 :
679 0 : return dmabuf;
680 :
681 : err_dmabuf:
682 : if (!resv)
683 : dma_resv_fini(dmabuf->resv);
684 : kfree(dmabuf);
685 : err_file:
686 0 : fput(file);
687 : err_module:
688 0 : module_put(exp_info->owner);
689 0 : return ERR_PTR(ret);
690 : }
691 : EXPORT_SYMBOL_NS_GPL(dma_buf_export, DMA_BUF);
692 :
693 : /**
694 : * dma_buf_fd - returns a file descriptor for the given struct dma_buf
695 : * @dmabuf: [in] pointer to dma_buf for which fd is required.
696 : * @flags: [in] flags to give to fd
697 : *
698 : * On success, returns an associated 'fd'. Else, returns error.
699 : */
700 0 : int dma_buf_fd(struct dma_buf *dmabuf, int flags)
701 : {
702 : int fd;
703 :
704 0 : if (!dmabuf || !dmabuf->file)
705 : return -EINVAL;
706 :
707 0 : fd = get_unused_fd_flags(flags);
708 0 : if (fd < 0)
709 : return fd;
710 :
711 0 : fd_install(fd, dmabuf->file);
712 :
713 0 : return fd;
714 : }
715 : EXPORT_SYMBOL_NS_GPL(dma_buf_fd, DMA_BUF);
716 :
717 : /**
718 : * dma_buf_get - returns the struct dma_buf related to an fd
719 : * @fd: [in] fd associated with the struct dma_buf to be returned
720 : *
721 : * On success, returns the struct dma_buf associated with an fd; uses
722 : * file's refcounting done by fget to increase refcount. returns ERR_PTR
723 : * otherwise.
724 : */
725 0 : struct dma_buf *dma_buf_get(int fd)
726 : {
727 : struct file *file;
728 :
729 0 : file = fget(fd);
730 :
731 0 : if (!file)
732 : return ERR_PTR(-EBADF);
733 :
734 0 : if (!is_dma_buf_file(file)) {
735 0 : fput(file);
736 0 : return ERR_PTR(-EINVAL);
737 : }
738 :
739 0 : return file->private_data;
740 : }
741 : EXPORT_SYMBOL_NS_GPL(dma_buf_get, DMA_BUF);
742 :
743 : /**
744 : * dma_buf_put - decreases refcount of the buffer
745 : * @dmabuf: [in] buffer to reduce refcount of
746 : *
747 : * Uses file's refcounting done implicitly by fput().
748 : *
749 : * If, as a result of this call, the refcount becomes 0, the 'release' file
750 : * operation related to this fd is called. It calls &dma_buf_ops.release vfunc
751 : * in turn, and frees the memory allocated for dmabuf when exported.
752 : */
753 0 : void dma_buf_put(struct dma_buf *dmabuf)
754 : {
755 0 : if (WARN_ON(!dmabuf || !dmabuf->file))
756 : return;
757 :
758 0 : fput(dmabuf->file);
759 : }
760 : EXPORT_SYMBOL_NS_GPL(dma_buf_put, DMA_BUF);
761 :
762 : static void mangle_sg_table(struct sg_table *sg_table)
763 : {
764 : #ifdef CONFIG_DMABUF_DEBUG
765 : int i;
766 : struct scatterlist *sg;
767 :
768 : /* To catch abuse of the underlying struct page by importers mix
769 : * up the bits, but take care to preserve the low SG_ bits to
770 : * not corrupt the sgt. The mixing is undone in __unmap_dma_buf
771 : * before passing the sgt back to the exporter. */
772 : for_each_sgtable_sg(sg_table, sg, i)
773 : sg->page_link ^= ~0xffUL;
774 : #endif
775 :
776 : }
777 0 : static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,
778 : enum dma_data_direction direction)
779 : {
780 : struct sg_table *sg_table;
781 : signed long ret;
782 :
783 0 : sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
784 0 : if (IS_ERR_OR_NULL(sg_table))
785 : return sg_table;
786 :
787 0 : if (!dma_buf_attachment_is_dynamic(attach)) {
788 0 : ret = dma_resv_wait_timeout(attach->dmabuf->resv,
789 : DMA_RESV_USAGE_KERNEL, true,
790 : MAX_SCHEDULE_TIMEOUT);
791 0 : if (ret < 0) {
792 0 : attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
793 : direction);
794 0 : return ERR_PTR(ret);
795 : }
796 : }
797 :
798 : mangle_sg_table(sg_table);
799 : return sg_table;
800 : }
801 :
802 : /**
803 : * DOC: locking convention
804 : *
805 : * In order to avoid deadlock situations between dma-buf exports and importers,
806 : * all dma-buf API users must follow the common dma-buf locking convention.
807 : *
808 : * Convention for importers
809 : *
810 : * 1. Importers must hold the dma-buf reservation lock when calling these
811 : * functions:
812 : *
813 : * - dma_buf_pin()
814 : * - dma_buf_unpin()
815 : * - dma_buf_map_attachment()
816 : * - dma_buf_unmap_attachment()
817 : * - dma_buf_vmap()
818 : * - dma_buf_vunmap()
819 : *
820 : * 2. Importers must not hold the dma-buf reservation lock when calling these
821 : * functions:
822 : *
823 : * - dma_buf_attach()
824 : * - dma_buf_dynamic_attach()
825 : * - dma_buf_detach()
826 : * - dma_buf_export()
827 : * - dma_buf_fd()
828 : * - dma_buf_get()
829 : * - dma_buf_put()
830 : * - dma_buf_mmap()
831 : * - dma_buf_begin_cpu_access()
832 : * - dma_buf_end_cpu_access()
833 : * - dma_buf_map_attachment_unlocked()
834 : * - dma_buf_unmap_attachment_unlocked()
835 : * - dma_buf_vmap_unlocked()
836 : * - dma_buf_vunmap_unlocked()
837 : *
838 : * Convention for exporters
839 : *
840 : * 1. These &dma_buf_ops callbacks are invoked with unlocked dma-buf
841 : * reservation and exporter can take the lock:
842 : *
843 : * - &dma_buf_ops.attach()
844 : * - &dma_buf_ops.detach()
845 : * - &dma_buf_ops.release()
846 : * - &dma_buf_ops.begin_cpu_access()
847 : * - &dma_buf_ops.end_cpu_access()
848 : * - &dma_buf_ops.mmap()
849 : *
850 : * 2. These &dma_buf_ops callbacks are invoked with locked dma-buf
851 : * reservation and exporter can't take the lock:
852 : *
853 : * - &dma_buf_ops.pin()
854 : * - &dma_buf_ops.unpin()
855 : * - &dma_buf_ops.map_dma_buf()
856 : * - &dma_buf_ops.unmap_dma_buf()
857 : * - &dma_buf_ops.vmap()
858 : * - &dma_buf_ops.vunmap()
859 : *
860 : * 3. Exporters must hold the dma-buf reservation lock when calling these
861 : * functions:
862 : *
863 : * - dma_buf_move_notify()
864 : */
865 :
866 : /**
867 : * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list
868 : * @dmabuf: [in] buffer to attach device to.
869 : * @dev: [in] device to be attached.
870 : * @importer_ops: [in] importer operations for the attachment
871 : * @importer_priv: [in] importer private pointer for the attachment
872 : *
873 : * Returns struct dma_buf_attachment pointer for this attachment. Attachments
874 : * must be cleaned up by calling dma_buf_detach().
875 : *
876 : * Optionally this calls &dma_buf_ops.attach to allow device-specific attach
877 : * functionality.
878 : *
879 : * Returns:
880 : *
881 : * A pointer to newly created &dma_buf_attachment on success, or a negative
882 : * error code wrapped into a pointer on failure.
883 : *
884 : * Note that this can fail if the backing storage of @dmabuf is in a place not
885 : * accessible to @dev, and cannot be moved to a more suitable place. This is
886 : * indicated with the error code -EBUSY.
887 : */
888 : struct dma_buf_attachment *
889 0 : dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
890 : const struct dma_buf_attach_ops *importer_ops,
891 : void *importer_priv)
892 : {
893 : struct dma_buf_attachment *attach;
894 : int ret;
895 :
896 0 : if (WARN_ON(!dmabuf || !dev))
897 : return ERR_PTR(-EINVAL);
898 :
899 0 : if (WARN_ON(importer_ops && !importer_ops->move_notify))
900 : return ERR_PTR(-EINVAL);
901 :
902 0 : attach = kzalloc(sizeof(*attach), GFP_KERNEL);
903 0 : if (!attach)
904 : return ERR_PTR(-ENOMEM);
905 :
906 0 : attach->dev = dev;
907 0 : attach->dmabuf = dmabuf;
908 0 : if (importer_ops)
909 0 : attach->peer2peer = importer_ops->allow_peer2peer;
910 0 : attach->importer_ops = importer_ops;
911 0 : attach->importer_priv = importer_priv;
912 :
913 0 : if (dmabuf->ops->attach) {
914 0 : ret = dmabuf->ops->attach(dmabuf, attach);
915 0 : if (ret)
916 : goto err_attach;
917 : }
918 0 : dma_resv_lock(dmabuf->resv, NULL);
919 0 : list_add(&attach->node, &dmabuf->attachments);
920 0 : dma_resv_unlock(dmabuf->resv);
921 :
922 : /* When either the importer or the exporter can't handle dynamic
923 : * mappings we cache the mapping here to avoid issues with the
924 : * reservation object lock.
925 : */
926 0 : if (dma_buf_attachment_is_dynamic(attach) !=
927 0 : dma_buf_is_dynamic(dmabuf)) {
928 : struct sg_table *sgt;
929 :
930 0 : dma_resv_lock(attach->dmabuf->resv, NULL);
931 0 : if (dma_buf_is_dynamic(attach->dmabuf)) {
932 0 : ret = dmabuf->ops->pin(attach);
933 0 : if (ret)
934 : goto err_unlock;
935 : }
936 :
937 0 : sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
938 0 : if (!sgt)
939 0 : sgt = ERR_PTR(-ENOMEM);
940 0 : if (IS_ERR(sgt)) {
941 0 : ret = PTR_ERR(sgt);
942 : goto err_unpin;
943 : }
944 0 : dma_resv_unlock(attach->dmabuf->resv);
945 0 : attach->sgt = sgt;
946 0 : attach->dir = DMA_BIDIRECTIONAL;
947 : }
948 :
949 : return attach;
950 :
951 : err_attach:
952 0 : kfree(attach);
953 0 : return ERR_PTR(ret);
954 :
955 : err_unpin:
956 0 : if (dma_buf_is_dynamic(attach->dmabuf))
957 0 : dmabuf->ops->unpin(attach);
958 :
959 : err_unlock:
960 0 : dma_resv_unlock(attach->dmabuf->resv);
961 :
962 0 : dma_buf_detach(dmabuf, attach);
963 0 : return ERR_PTR(ret);
964 : }
965 : EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, DMA_BUF);
966 :
967 : /**
968 : * dma_buf_attach - Wrapper for dma_buf_dynamic_attach
969 : * @dmabuf: [in] buffer to attach device to.
970 : * @dev: [in] device to be attached.
971 : *
972 : * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static
973 : * mapping.
974 : */
975 0 : struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
976 : struct device *dev)
977 : {
978 0 : return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
979 : }
980 : EXPORT_SYMBOL_NS_GPL(dma_buf_attach, DMA_BUF);
981 :
982 : static void __unmap_dma_buf(struct dma_buf_attachment *attach,
983 : struct sg_table *sg_table,
984 : enum dma_data_direction direction)
985 : {
986 : /* uses XOR, hence this unmangles */
987 0 : mangle_sg_table(sg_table);
988 :
989 0 : attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
990 : }
991 :
992 : /**
993 : * dma_buf_detach - Remove the given attachment from dmabuf's attachments list
994 : * @dmabuf: [in] buffer to detach from.
995 : * @attach: [in] attachment to be detached; is free'd after this call.
996 : *
997 : * Clean up a device attachment obtained by calling dma_buf_attach().
998 : *
999 : * Optionally this calls &dma_buf_ops.detach for device-specific detach.
1000 : */
1001 0 : void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
1002 : {
1003 0 : if (WARN_ON(!dmabuf || !attach || dmabuf != attach->dmabuf))
1004 : return;
1005 :
1006 0 : dma_resv_lock(dmabuf->resv, NULL);
1007 :
1008 0 : if (attach->sgt) {
1009 :
1010 0 : __unmap_dma_buf(attach, attach->sgt, attach->dir);
1011 :
1012 0 : if (dma_buf_is_dynamic(attach->dmabuf))
1013 0 : dmabuf->ops->unpin(attach);
1014 : }
1015 0 : list_del(&attach->node);
1016 :
1017 0 : dma_resv_unlock(dmabuf->resv);
1018 :
1019 0 : if (dmabuf->ops->detach)
1020 0 : dmabuf->ops->detach(dmabuf, attach);
1021 :
1022 0 : kfree(attach);
1023 : }
1024 : EXPORT_SYMBOL_NS_GPL(dma_buf_detach, DMA_BUF);
1025 :
1026 : /**
1027 : * dma_buf_pin - Lock down the DMA-buf
1028 : * @attach: [in] attachment which should be pinned
1029 : *
1030 : * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may
1031 : * call this, and only for limited use cases like scanout and not for temporary
1032 : * pin operations. It is not permitted to allow userspace to pin arbitrary
1033 : * amounts of buffers through this interface.
1034 : *
1035 : * Buffers must be unpinned by calling dma_buf_unpin().
1036 : *
1037 : * Returns:
1038 : * 0 on success, negative error code on failure.
1039 : */
1040 0 : int dma_buf_pin(struct dma_buf_attachment *attach)
1041 : {
1042 0 : struct dma_buf *dmabuf = attach->dmabuf;
1043 0 : int ret = 0;
1044 :
1045 0 : WARN_ON(!dma_buf_attachment_is_dynamic(attach));
1046 :
1047 : dma_resv_assert_held(dmabuf->resv);
1048 :
1049 0 : if (dmabuf->ops->pin)
1050 0 : ret = dmabuf->ops->pin(attach);
1051 :
1052 0 : return ret;
1053 : }
1054 : EXPORT_SYMBOL_NS_GPL(dma_buf_pin, DMA_BUF);
1055 :
1056 : /**
1057 : * dma_buf_unpin - Unpin a DMA-buf
1058 : * @attach: [in] attachment which should be unpinned
1059 : *
1060 : * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move
1061 : * any mapping of @attach again and inform the importer through
1062 : * &dma_buf_attach_ops.move_notify.
1063 : */
1064 0 : void dma_buf_unpin(struct dma_buf_attachment *attach)
1065 : {
1066 0 : struct dma_buf *dmabuf = attach->dmabuf;
1067 :
1068 0 : WARN_ON(!dma_buf_attachment_is_dynamic(attach));
1069 :
1070 : dma_resv_assert_held(dmabuf->resv);
1071 :
1072 0 : if (dmabuf->ops->unpin)
1073 0 : dmabuf->ops->unpin(attach);
1074 0 : }
1075 : EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, DMA_BUF);
1076 :
1077 : /**
1078 : * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
1079 : * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
1080 : * dma_buf_ops.
1081 : * @attach: [in] attachment whose scatterlist is to be returned
1082 : * @direction: [in] direction of DMA transfer
1083 : *
1084 : * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
1085 : * on error. May return -EINTR if it is interrupted by a signal.
1086 : *
1087 : * On success, the DMA addresses and lengths in the returned scatterlist are
1088 : * PAGE_SIZE aligned.
1089 : *
1090 : * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
1091 : * the underlying backing storage is pinned for as long as a mapping exists,
1092 : * therefore users/importers should not hold onto a mapping for undue amounts of
1093 : * time.
1094 : *
1095 : * Important: Dynamic importers must wait for the exclusive fence of the struct
1096 : * dma_resv attached to the DMA-BUF first.
1097 : */
1098 0 : struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
1099 : enum dma_data_direction direction)
1100 : {
1101 : struct sg_table *sg_table;
1102 : int r;
1103 :
1104 : might_sleep();
1105 :
1106 0 : if (WARN_ON(!attach || !attach->dmabuf))
1107 : return ERR_PTR(-EINVAL);
1108 :
1109 0 : dma_resv_assert_held(attach->dmabuf->resv);
1110 :
1111 0 : if (attach->sgt) {
1112 : /*
1113 : * Two mappings with different directions for the same
1114 : * attachment are not allowed.
1115 : */
1116 0 : if (attach->dir != direction &&
1117 : attach->dir != DMA_BIDIRECTIONAL)
1118 : return ERR_PTR(-EBUSY);
1119 :
1120 0 : return attach->sgt;
1121 : }
1122 :
1123 0 : if (dma_buf_is_dynamic(attach->dmabuf)) {
1124 : if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
1125 0 : r = attach->dmabuf->ops->pin(attach);
1126 0 : if (r)
1127 0 : return ERR_PTR(r);
1128 : }
1129 : }
1130 :
1131 0 : sg_table = __map_dma_buf(attach, direction);
1132 0 : if (!sg_table)
1133 0 : sg_table = ERR_PTR(-ENOMEM);
1134 :
1135 0 : if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&
1136 : !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
1137 0 : attach->dmabuf->ops->unpin(attach);
1138 :
1139 0 : if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
1140 0 : attach->sgt = sg_table;
1141 0 : attach->dir = direction;
1142 : }
1143 :
1144 : #ifdef CONFIG_DMA_API_DEBUG
1145 : if (!IS_ERR(sg_table)) {
1146 : struct scatterlist *sg;
1147 : u64 addr;
1148 : int len;
1149 : int i;
1150 :
1151 : for_each_sgtable_dma_sg(sg_table, sg, i) {
1152 : addr = sg_dma_address(sg);
1153 : len = sg_dma_len(sg);
1154 : if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {
1155 : pr_debug("%s: addr %llx or len %x is not page aligned!\n",
1156 : __func__, addr, len);
1157 : }
1158 : }
1159 : }
1160 : #endif /* CONFIG_DMA_API_DEBUG */
1161 : return sg_table;
1162 : }
1163 : EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, DMA_BUF);
1164 :
1165 : /**
1166 : * dma_buf_map_attachment_unlocked - Returns the scatterlist table of the attachment;
1167 : * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
1168 : * dma_buf_ops.
1169 : * @attach: [in] attachment whose scatterlist is to be returned
1170 : * @direction: [in] direction of DMA transfer
1171 : *
1172 : * Unlocked variant of dma_buf_map_attachment().
1173 : */
1174 : struct sg_table *
1175 0 : dma_buf_map_attachment_unlocked(struct dma_buf_attachment *attach,
1176 : enum dma_data_direction direction)
1177 : {
1178 : struct sg_table *sg_table;
1179 :
1180 : might_sleep();
1181 :
1182 0 : if (WARN_ON(!attach || !attach->dmabuf))
1183 : return ERR_PTR(-EINVAL);
1184 :
1185 0 : dma_resv_lock(attach->dmabuf->resv, NULL);
1186 0 : sg_table = dma_buf_map_attachment(attach, direction);
1187 0 : dma_resv_unlock(attach->dmabuf->resv);
1188 :
1189 0 : return sg_table;
1190 : }
1191 : EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment_unlocked, DMA_BUF);
1192 :
1193 : /**
1194 : * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
1195 : * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
1196 : * dma_buf_ops.
1197 : * @attach: [in] attachment to unmap buffer from
1198 : * @sg_table: [in] scatterlist info of the buffer to unmap
1199 : * @direction: [in] direction of DMA transfer
1200 : *
1201 : * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
1202 : */
1203 0 : void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
1204 : struct sg_table *sg_table,
1205 : enum dma_data_direction direction)
1206 : {
1207 : might_sleep();
1208 :
1209 0 : if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
1210 : return;
1211 :
1212 0 : dma_resv_assert_held(attach->dmabuf->resv);
1213 :
1214 0 : if (attach->sgt == sg_table)
1215 : return;
1216 :
1217 0 : __unmap_dma_buf(attach, sg_table, direction);
1218 :
1219 0 : if (dma_buf_is_dynamic(attach->dmabuf) &&
1220 : !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
1221 0 : dma_buf_unpin(attach);
1222 : }
1223 : EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, DMA_BUF);
1224 :
1225 : /**
1226 : * dma_buf_unmap_attachment_unlocked - unmaps and decreases usecount of the buffer;might
1227 : * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
1228 : * dma_buf_ops.
1229 : * @attach: [in] attachment to unmap buffer from
1230 : * @sg_table: [in] scatterlist info of the buffer to unmap
1231 : * @direction: [in] direction of DMA transfer
1232 : *
1233 : * Unlocked variant of dma_buf_unmap_attachment().
1234 : */
1235 0 : void dma_buf_unmap_attachment_unlocked(struct dma_buf_attachment *attach,
1236 : struct sg_table *sg_table,
1237 : enum dma_data_direction direction)
1238 : {
1239 : might_sleep();
1240 :
1241 0 : if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
1242 : return;
1243 :
1244 0 : dma_resv_lock(attach->dmabuf->resv, NULL);
1245 0 : dma_buf_unmap_attachment(attach, sg_table, direction);
1246 0 : dma_resv_unlock(attach->dmabuf->resv);
1247 : }
1248 : EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment_unlocked, DMA_BUF);
1249 :
1250 : /**
1251 : * dma_buf_move_notify - notify attachments that DMA-buf is moving
1252 : *
1253 : * @dmabuf: [in] buffer which is moving
1254 : *
1255 : * Informs all attachments that they need to destroy and recreate all their
1256 : * mappings.
1257 : */
1258 0 : void dma_buf_move_notify(struct dma_buf *dmabuf)
1259 : {
1260 : struct dma_buf_attachment *attach;
1261 :
1262 : dma_resv_assert_held(dmabuf->resv);
1263 :
1264 0 : list_for_each_entry(attach, &dmabuf->attachments, node)
1265 0 : if (attach->importer_ops)
1266 0 : attach->importer_ops->move_notify(attach);
1267 0 : }
1268 : EXPORT_SYMBOL_NS_GPL(dma_buf_move_notify, DMA_BUF);
1269 :
1270 : /**
1271 : * DOC: cpu access
1272 : *
1273 : * There are multiple reasons for supporting CPU access to a dma buffer object:
1274 : *
1275 : * - Fallback operations in the kernel, for example when a device is connected
1276 : * over USB and the kernel needs to shuffle the data around first before
1277 : * sending it away. Cache coherency is handled by bracketing any transactions
1278 : * with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
1279 : * access.
1280 : *
1281 : * Since for most kernel internal dma-buf accesses need the entire buffer, a
1282 : * vmap interface is introduced. Note that on very old 32-bit architectures
1283 : * vmalloc space might be limited and result in vmap calls failing.
1284 : *
1285 : * Interfaces::
1286 : *
1287 : * void \*dma_buf_vmap(struct dma_buf \*dmabuf, struct iosys_map \*map)
1288 : * void dma_buf_vunmap(struct dma_buf \*dmabuf, struct iosys_map \*map)
1289 : *
1290 : * The vmap call can fail if there is no vmap support in the exporter, or if
1291 : * it runs out of vmalloc space. Note that the dma-buf layer keeps a reference
1292 : * count for all vmap access and calls down into the exporter's vmap function
1293 : * only when no vmapping exists, and only unmaps it once. Protection against
1294 : * concurrent vmap/vunmap calls is provided by taking the &dma_buf.lock mutex.
1295 : *
1296 : * - For full compatibility on the importer side with existing userspace
1297 : * interfaces, which might already support mmap'ing buffers. This is needed in
1298 : * many processing pipelines (e.g. feeding a software rendered image into a
1299 : * hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION
1300 : * framework already supported this and for DMA buffer file descriptors to
1301 : * replace ION buffers mmap support was needed.
1302 : *
1303 : * There is no special interfaces, userspace simply calls mmap on the dma-buf
1304 : * fd. But like for CPU access there's a need to bracket the actual access,
1305 : * which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that
1306 : * DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must
1307 : * be restarted.
1308 : *
1309 : * Some systems might need some sort of cache coherency management e.g. when
1310 : * CPU and GPU domains are being accessed through dma-buf at the same time.
1311 : * To circumvent this problem there are begin/end coherency markers, that
1312 : * forward directly to existing dma-buf device drivers vfunc hooks. Userspace
1313 : * can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
1314 : * sequence would be used like following:
1315 : *
1316 : * - mmap dma-buf fd
1317 : * - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
1318 : * to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
1319 : * want (with the new data being consumed by say the GPU or the scanout
1320 : * device)
1321 : * - munmap once you don't need the buffer any more
1322 : *
1323 : * For correctness and optimal performance, it is always required to use
1324 : * SYNC_START and SYNC_END before and after, respectively, when accessing the
1325 : * mapped address. Userspace cannot rely on coherent access, even when there
1326 : * are systems where it just works without calling these ioctls.
1327 : *
1328 : * - And as a CPU fallback in userspace processing pipelines.
1329 : *
1330 : * Similar to the motivation for kernel cpu access it is again important that
1331 : * the userspace code of a given importing subsystem can use the same
1332 : * interfaces with a imported dma-buf buffer object as with a native buffer
1333 : * object. This is especially important for drm where the userspace part of
1334 : * contemporary OpenGL, X, and other drivers is huge, and reworking them to
1335 : * use a different way to mmap a buffer rather invasive.
1336 : *
1337 : * The assumption in the current dma-buf interfaces is that redirecting the
1338 : * initial mmap is all that's needed. A survey of some of the existing
1339 : * subsystems shows that no driver seems to do any nefarious thing like
1340 : * syncing up with outstanding asynchronous processing on the device or
1341 : * allocating special resources at fault time. So hopefully this is good
1342 : * enough, since adding interfaces to intercept pagefaults and allow pte
1343 : * shootdowns would increase the complexity quite a bit.
1344 : *
1345 : * Interface::
1346 : *
1347 : * int dma_buf_mmap(struct dma_buf \*, struct vm_area_struct \*,
1348 : * unsigned long);
1349 : *
1350 : * If the importing subsystem simply provides a special-purpose mmap call to
1351 : * set up a mapping in userspace, calling do_mmap with &dma_buf.file will
1352 : * equally achieve that for a dma-buf object.
1353 : */
1354 :
1355 : static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1356 : enum dma_data_direction direction)
1357 : {
1358 0 : bool write = (direction == DMA_BIDIRECTIONAL ||
1359 : direction == DMA_TO_DEVICE);
1360 0 : struct dma_resv *resv = dmabuf->resv;
1361 : long ret;
1362 :
1363 : /* Wait on any implicit rendering fences */
1364 0 : ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),
1365 : true, MAX_SCHEDULE_TIMEOUT);
1366 0 : if (ret < 0)
1367 0 : return ret;
1368 :
1369 : return 0;
1370 : }
1371 :
1372 : /**
1373 : * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
1374 : * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
1375 : * preparations. Coherency is only guaranteed in the specified range for the
1376 : * specified access direction.
1377 : * @dmabuf: [in] buffer to prepare cpu access for.
1378 : * @direction: [in] direction of access.
1379 : *
1380 : * After the cpu access is complete the caller should call
1381 : * dma_buf_end_cpu_access(). Only when cpu access is bracketed by both calls is
1382 : * it guaranteed to be coherent with other DMA access.
1383 : *
1384 : * This function will also wait for any DMA transactions tracked through
1385 : * implicit synchronization in &dma_buf.resv. For DMA transactions with explicit
1386 : * synchronization this function will only ensure cache coherency, callers must
1387 : * ensure synchronization with such DMA transactions on their own.
1388 : *
1389 : * Can return negative error values, returns 0 on success.
1390 : */
1391 0 : int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1392 : enum dma_data_direction direction)
1393 : {
1394 0 : int ret = 0;
1395 :
1396 0 : if (WARN_ON(!dmabuf))
1397 : return -EINVAL;
1398 :
1399 : might_lock(&dmabuf->resv->lock.base);
1400 :
1401 0 : if (dmabuf->ops->begin_cpu_access)
1402 0 : ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
1403 :
1404 : /* Ensure that all fences are waited upon - but we first allow
1405 : * the native handler the chance to do so more efficiently if it
1406 : * chooses. A double invocation here will be reasonably cheap no-op.
1407 : */
1408 0 : if (ret == 0)
1409 0 : ret = __dma_buf_begin_cpu_access(dmabuf, direction);
1410 :
1411 : return ret;
1412 : }
1413 : EXPORT_SYMBOL_NS_GPL(dma_buf_begin_cpu_access, DMA_BUF);
1414 :
1415 : /**
1416 : * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
1417 : * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
1418 : * actions. Coherency is only guaranteed in the specified range for the
1419 : * specified access direction.
1420 : * @dmabuf: [in] buffer to complete cpu access for.
1421 : * @direction: [in] direction of access.
1422 : *
1423 : * This terminates CPU access started with dma_buf_begin_cpu_access().
1424 : *
1425 : * Can return negative error values, returns 0 on success.
1426 : */
1427 0 : int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
1428 : enum dma_data_direction direction)
1429 : {
1430 0 : int ret = 0;
1431 :
1432 0 : WARN_ON(!dmabuf);
1433 :
1434 : might_lock(&dmabuf->resv->lock.base);
1435 :
1436 0 : if (dmabuf->ops->end_cpu_access)
1437 0 : ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
1438 :
1439 0 : return ret;
1440 : }
1441 : EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, DMA_BUF);
1442 :
1443 :
1444 : /**
1445 : * dma_buf_mmap - Setup up a userspace mmap with the given vma
1446 : * @dmabuf: [in] buffer that should back the vma
1447 : * @vma: [in] vma for the mmap
1448 : * @pgoff: [in] offset in pages where this mmap should start within the
1449 : * dma-buf buffer.
1450 : *
1451 : * This function adjusts the passed in vma so that it points at the file of the
1452 : * dma_buf operation. It also adjusts the starting pgoff and does bounds
1453 : * checking on the size of the vma. Then it calls the exporters mmap function to
1454 : * set up the mapping.
1455 : *
1456 : * Can return negative error values, returns 0 on success.
1457 : */
1458 0 : int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
1459 : unsigned long pgoff)
1460 : {
1461 0 : if (WARN_ON(!dmabuf || !vma))
1462 : return -EINVAL;
1463 :
1464 : /* check if buffer supports mmap */
1465 0 : if (!dmabuf->ops->mmap)
1466 : return -EINVAL;
1467 :
1468 : /* check for offset overflow */
1469 0 : if (pgoff + vma_pages(vma) < pgoff)
1470 : return -EOVERFLOW;
1471 :
1472 : /* check for overflowing the buffer's size */
1473 0 : if (pgoff + vma_pages(vma) >
1474 0 : dmabuf->size >> PAGE_SHIFT)
1475 : return -EINVAL;
1476 :
1477 : /* readjust the vma */
1478 0 : vma_set_file(vma, dmabuf->file);
1479 0 : vma->vm_pgoff = pgoff;
1480 :
1481 0 : return dmabuf->ops->mmap(dmabuf, vma);
1482 : }
1483 : EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
1484 :
1485 : /**
1486 : * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
1487 : * address space. Same restrictions as for vmap and friends apply.
1488 : * @dmabuf: [in] buffer to vmap
1489 : * @map: [out] returns the vmap pointer
1490 : *
1491 : * This call may fail due to lack of virtual mapping address space.
1492 : * These calls are optional in drivers. The intended use for them
1493 : * is for mapping objects linear in kernel space for high use objects.
1494 : *
1495 : * To ensure coherency users must call dma_buf_begin_cpu_access() and
1496 : * dma_buf_end_cpu_access() around any cpu access performed through this
1497 : * mapping.
1498 : *
1499 : * Returns 0 on success, or a negative errno code otherwise.
1500 : */
1501 0 : int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
1502 : {
1503 : struct iosys_map ptr;
1504 : int ret;
1505 :
1506 0 : iosys_map_clear(map);
1507 :
1508 0 : if (WARN_ON(!dmabuf))
1509 : return -EINVAL;
1510 :
1511 : dma_resv_assert_held(dmabuf->resv);
1512 :
1513 0 : if (!dmabuf->ops->vmap)
1514 : return -EINVAL;
1515 :
1516 0 : if (dmabuf->vmapping_counter) {
1517 0 : dmabuf->vmapping_counter++;
1518 0 : BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
1519 0 : *map = dmabuf->vmap_ptr;
1520 0 : return 0;
1521 : }
1522 :
1523 0 : BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
1524 :
1525 0 : ret = dmabuf->ops->vmap(dmabuf, &ptr);
1526 0 : if (WARN_ON_ONCE(ret))
1527 : return ret;
1528 :
1529 0 : dmabuf->vmap_ptr = ptr;
1530 0 : dmabuf->vmapping_counter = 1;
1531 :
1532 0 : *map = dmabuf->vmap_ptr;
1533 :
1534 0 : return 0;
1535 : }
1536 : EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
1537 :
1538 : /**
1539 : * dma_buf_vmap_unlocked - Create virtual mapping for the buffer object into kernel
1540 : * address space. Same restrictions as for vmap and friends apply.
1541 : * @dmabuf: [in] buffer to vmap
1542 : * @map: [out] returns the vmap pointer
1543 : *
1544 : * Unlocked version of dma_buf_vmap()
1545 : *
1546 : * Returns 0 on success, or a negative errno code otherwise.
1547 : */
1548 0 : int dma_buf_vmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
1549 : {
1550 : int ret;
1551 :
1552 0 : iosys_map_clear(map);
1553 :
1554 0 : if (WARN_ON(!dmabuf))
1555 : return -EINVAL;
1556 :
1557 0 : dma_resv_lock(dmabuf->resv, NULL);
1558 0 : ret = dma_buf_vmap(dmabuf, map);
1559 0 : dma_resv_unlock(dmabuf->resv);
1560 :
1561 0 : return ret;
1562 : }
1563 : EXPORT_SYMBOL_NS_GPL(dma_buf_vmap_unlocked, DMA_BUF);
1564 :
1565 : /**
1566 : * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
1567 : * @dmabuf: [in] buffer to vunmap
1568 : * @map: [in] vmap pointer to vunmap
1569 : */
1570 0 : void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
1571 : {
1572 0 : if (WARN_ON(!dmabuf))
1573 : return;
1574 :
1575 : dma_resv_assert_held(dmabuf->resv);
1576 :
1577 0 : BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
1578 0 : BUG_ON(dmabuf->vmapping_counter == 0);
1579 0 : BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
1580 :
1581 0 : if (--dmabuf->vmapping_counter == 0) {
1582 0 : if (dmabuf->ops->vunmap)
1583 0 : dmabuf->ops->vunmap(dmabuf, map);
1584 0 : iosys_map_clear(&dmabuf->vmap_ptr);
1585 : }
1586 : }
1587 : EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
1588 :
1589 : /**
1590 : * dma_buf_vunmap_unlocked - Unmap a vmap obtained by dma_buf_vmap.
1591 : * @dmabuf: [in] buffer to vunmap
1592 : * @map: [in] vmap pointer to vunmap
1593 : */
1594 0 : void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
1595 : {
1596 0 : if (WARN_ON(!dmabuf))
1597 : return;
1598 :
1599 0 : dma_resv_lock(dmabuf->resv, NULL);
1600 0 : dma_buf_vunmap(dmabuf, map);
1601 0 : dma_resv_unlock(dmabuf->resv);
1602 : }
1603 : EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, DMA_BUF);
1604 :
1605 : #ifdef CONFIG_DEBUG_FS
1606 : static int dma_buf_debug_show(struct seq_file *s, void *unused)
1607 : {
1608 : struct dma_buf *buf_obj;
1609 : struct dma_buf_attachment *attach_obj;
1610 : int count = 0, attach_count;
1611 : size_t size = 0;
1612 : int ret;
1613 :
1614 : ret = mutex_lock_interruptible(&db_list.lock);
1615 :
1616 : if (ret)
1617 : return ret;
1618 :
1619 : seq_puts(s, "\nDma-buf Objects:\n");
1620 : seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",
1621 : "size", "flags", "mode", "count", "ino");
1622 :
1623 : list_for_each_entry(buf_obj, &db_list.head, list_node) {
1624 :
1625 : ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
1626 : if (ret)
1627 : goto error_unlock;
1628 :
1629 :
1630 : spin_lock(&buf_obj->name_lock);
1631 : seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
1632 : buf_obj->size,
1633 : buf_obj->file->f_flags, buf_obj->file->f_mode,
1634 : file_count(buf_obj->file),
1635 : buf_obj->exp_name,
1636 : file_inode(buf_obj->file)->i_ino,
1637 : buf_obj->name ?: "<none>");
1638 : spin_unlock(&buf_obj->name_lock);
1639 :
1640 : dma_resv_describe(buf_obj->resv, s);
1641 :
1642 : seq_puts(s, "\tAttached Devices:\n");
1643 : attach_count = 0;
1644 :
1645 : list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
1646 : seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
1647 : attach_count++;
1648 : }
1649 : dma_resv_unlock(buf_obj->resv);
1650 :
1651 : seq_printf(s, "Total %d devices attached\n\n",
1652 : attach_count);
1653 :
1654 : count++;
1655 : size += buf_obj->size;
1656 : }
1657 :
1658 : seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
1659 :
1660 : mutex_unlock(&db_list.lock);
1661 : return 0;
1662 :
1663 : error_unlock:
1664 : mutex_unlock(&db_list.lock);
1665 : return ret;
1666 : }
1667 :
1668 : DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
1669 :
1670 : static struct dentry *dma_buf_debugfs_dir;
1671 :
1672 : static int dma_buf_init_debugfs(void)
1673 : {
1674 : struct dentry *d;
1675 : int err = 0;
1676 :
1677 : d = debugfs_create_dir("dma_buf", NULL);
1678 : if (IS_ERR(d))
1679 : return PTR_ERR(d);
1680 :
1681 : dma_buf_debugfs_dir = d;
1682 :
1683 : d = debugfs_create_file("bufinfo", S_IRUGO, dma_buf_debugfs_dir,
1684 : NULL, &dma_buf_debug_fops);
1685 : if (IS_ERR(d)) {
1686 : pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
1687 : debugfs_remove_recursive(dma_buf_debugfs_dir);
1688 : dma_buf_debugfs_dir = NULL;
1689 : err = PTR_ERR(d);
1690 : }
1691 :
1692 : return err;
1693 : }
1694 :
1695 : static void dma_buf_uninit_debugfs(void)
1696 : {
1697 : debugfs_remove_recursive(dma_buf_debugfs_dir);
1698 : }
1699 : #else
1700 : static inline int dma_buf_init_debugfs(void)
1701 : {
1702 : return 0;
1703 : }
1704 : static inline void dma_buf_uninit_debugfs(void)
1705 : {
1706 : }
1707 : #endif
1708 :
1709 1 : static int __init dma_buf_init(void)
1710 : {
1711 : int ret;
1712 :
1713 1 : ret = dma_buf_init_sysfs_statistics();
1714 : if (ret)
1715 : return ret;
1716 :
1717 1 : dma_buf_mnt = kern_mount(&dma_buf_fs_type);
1718 2 : if (IS_ERR(dma_buf_mnt))
1719 0 : return PTR_ERR(dma_buf_mnt);
1720 :
1721 1 : mutex_init(&db_list.lock);
1722 1 : INIT_LIST_HEAD(&db_list.head);
1723 : dma_buf_init_debugfs();
1724 1 : return 0;
1725 : }
1726 : subsys_initcall(dma_buf_init);
1727 :
1728 0 : static void __exit dma_buf_deinit(void)
1729 : {
1730 : dma_buf_uninit_debugfs();
1731 0 : kern_unmount(dma_buf_mnt);
1732 : dma_buf_uninit_sysfs_statistics();
1733 0 : }
1734 : __exitcall(dma_buf_deinit);
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