projects/linux·blob master · refs

1872 lines · 51.7 KiB

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 <[email protected]>
7 *
8 * Many thanks to linaro-mm-sig list, and specially
9 * Arnd Bergmann <[email protected]>, Rob Clark <[email protected]> and
10 * Daniel Vetter <[email protected]> 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/list.h>
23#include <linux/module.h>
24#include <linux/mutex.h>
25#include <linux/seq_file.h>
26#include <linux/sync_file.h>
27#include <linux/poll.h>
28#include <linux/dma-resv.h>
29#include <linux/mm.h>
30#include <linux/mount.h>
31#include <linux/pseudo_fs.h>
32
33#include <uapi/linux/dma-buf.h>
34#include <uapi/linux/magic.h>
35
36#define CREATE_TRACE_POINTS
37#include <trace/events/dma_buf.h>
38
39/*
40 * dmabuf->name must be accessed with holding dmabuf->name_lock.
41 * we need to take the lock around the tracepoint call itself where
42 * it is called in the code.
43 *
44 * Note: FUNC##_enabled() is a static branch that will only
45 * be set when the trace event is enabled.
46 */
47#define DMA_BUF_TRACE(FUNC, ...) \
48 do { \
49 /* Always expose lock if lockdep is enabled */ \
50 if (IS_ENABLED(CONFIG_LOCKDEP) || FUNC##_enabled()) { \
51 guard(spinlock)(&dmabuf->name_lock); \
52 FUNC(__VA_ARGS__); \
53 } \
54 } while (0)
55
56/* Wrapper to hide the sg_table page link from the importer */
57struct dma_buf_sg_table_wrapper {
58 struct sg_table *original;
59 struct sg_table wrapper;
60};
61
62static inline int is_dma_buf_file(struct file *);
63
64static DEFINE_MUTEX(dmabuf_list_mutex);
65static LIST_HEAD(dmabuf_list);
66
67static void __dma_buf_list_add(struct dma_buf *dmabuf)
68{
69 mutex_lock(&dmabuf_list_mutex);
70 list_add(&dmabuf->list_node, &dmabuf_list);
71 mutex_unlock(&dmabuf_list_mutex);
72}
73
74static void __dma_buf_list_del(struct dma_buf *dmabuf)
75{
76 if (!dmabuf)
77 return;
78
79 mutex_lock(&dmabuf_list_mutex);
80 list_del(&dmabuf->list_node);
81 mutex_unlock(&dmabuf_list_mutex);
82}
83
84/**
85 * dma_buf_iter_begin - begin iteration through global list of all DMA buffers
86 *
87 * Returns the first buffer in the global list of DMA-bufs that's not in the
88 * process of being destroyed. Increments that buffer's reference count to
89 * prevent buffer destruction. Callers must release the reference, either by
90 * continuing iteration with dma_buf_iter_next(), or with dma_buf_put().
91 *
92 * Return:
93 * * First buffer from global list, with refcount elevated
94 * * NULL if no active buffers are present
95 */
96struct dma_buf *dma_buf_iter_begin(void)
97{
98 struct dma_buf *ret = NULL, *dmabuf;
99
100 /*
101 * The list mutex does not protect a dmabuf's refcount, so it can be
102 * zeroed while we are iterating. We cannot call get_dma_buf() since the
103 * caller may not already own a reference to the buffer.
104 */
105 mutex_lock(&dmabuf_list_mutex);
106 list_for_each_entry(dmabuf, &dmabuf_list, list_node) {
107 if (file_ref_get(&dmabuf->file->f_ref)) {
108 ret = dmabuf;
109 break;
110 }
111 }
112 mutex_unlock(&dmabuf_list_mutex);
113 return ret;
114}
115
116/**
117 * dma_buf_iter_next - continue iteration through global list of all DMA buffers
118 * @dmabuf: [in] pointer to dma_buf
119 *
120 * Decrements the reference count on the provided buffer. Returns the next
121 * buffer from the remainder of the global list of DMA-bufs with its reference
122 * count incremented. Callers must release the reference, either by continuing
123 * iteration with dma_buf_iter_next(), or with dma_buf_put().
124 *
125 * Return:
126 * * Next buffer from global list, with refcount elevated
127 * * NULL if no additional active buffers are present
128 */
129struct dma_buf *dma_buf_iter_next(struct dma_buf *dmabuf)
130{
131 struct dma_buf *ret = NULL;
132
133 /*
134 * The list mutex does not protect a dmabuf's refcount, so it can be
135 * zeroed while we are iterating. We cannot call get_dma_buf() since the
136 * caller may not already own a reference to the buffer.
137 */
138 mutex_lock(&dmabuf_list_mutex);
139 dma_buf_put(dmabuf);
140 list_for_each_entry_continue(dmabuf, &dmabuf_list, list_node) {
141 if (file_ref_get(&dmabuf->file->f_ref)) {
142 ret = dmabuf;
143 break;
144 }
145 }
146 mutex_unlock(&dmabuf_list_mutex);
147 return ret;
148}
149
150static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
151{
152 struct dma_buf *dmabuf;
153 char name[DMA_BUF_NAME_LEN];
154 ssize_t ret = 0;
155
156 dmabuf = dentry->d_fsdata;
157 spin_lock(&dmabuf->name_lock);
158 if (dmabuf->name)
159 ret = strscpy(name, dmabuf->name, sizeof(name));
160 spin_unlock(&dmabuf->name_lock);
161
162 return dynamic_dname(buffer, buflen, "/%s:%s",
163 dentry->d_name.name, ret > 0 ? name : "");
164}
165
166static void dma_buf_release(struct dentry *dentry)
167{
168 struct dma_buf *dmabuf;
169
170 dmabuf = dentry->d_fsdata;
171 if (unlikely(!dmabuf))
172 return;
173
174 BUG_ON(dmabuf->vmapping_counter);
175
176 /*
177 * If you hit this BUG() it could mean:
178 * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else
179 * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback
180 */
181 BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
182
183 dmabuf->ops->release(dmabuf);
184
185 if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
186 dma_resv_fini(dmabuf->resv);
187
188 WARN_ON(!list_empty(&dmabuf->attachments));
189 module_put(dmabuf->owner);
190 kfree(dmabuf->name);
191 kfree(dmabuf);
192}
193
194static int dma_buf_file_release(struct inode *inode, struct file *file)
195{
196 if (!is_dma_buf_file(file))
197 return -EINVAL;
198
199 __dma_buf_list_del(file->private_data);
200
201 return 0;
202}
203
204static const struct dentry_operations dma_buf_dentry_ops = {
205 .d_dname = dmabuffs_dname,
206 .d_release = dma_buf_release,
207};
208
209static struct vfsmount *dma_buf_mnt;
210
211static int dma_buf_fs_init_context(struct fs_context *fc)
212{
213 struct pseudo_fs_context *ctx;
214
215 ctx = init_pseudo(fc, DMA_BUF_MAGIC);
216 if (!ctx)
217 return -ENOMEM;
218 ctx->dops = &dma_buf_dentry_ops;
219 return 0;
220}
221
222static struct file_system_type dma_buf_fs_type = {
223 .name = "dmabuf",
224 .init_fs_context = dma_buf_fs_init_context,
225 .kill_sb = kill_anon_super,
226};
227
228static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
229{
230 struct dma_buf *dmabuf;
231
232 if (!is_dma_buf_file(file))
233 return -EINVAL;
234
235 dmabuf = file->private_data;
236
237 /* check if buffer supports mmap */
238 if (!dmabuf->ops->mmap)
239 return -EINVAL;
240
241 /* check for overflowing the buffer's size */
242 if (vma->vm_pgoff + vma_pages(vma) >
243 dmabuf->size >> PAGE_SHIFT)
244 return -EINVAL;
245
246 DMA_BUF_TRACE(trace_dma_buf_mmap_internal, dmabuf);
247
248 return dmabuf->ops->mmap(dmabuf, vma);
249}
250
251static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
252{
253 struct dma_buf *dmabuf;
254 loff_t base;
255
256 if (!is_dma_buf_file(file))
257 return -EBADF;
258
259 dmabuf = file->private_data;
260
261 /* only support discovering the end of the buffer,
262 * but also allow SEEK_SET to maintain the idiomatic
263 * SEEK_END(0), SEEK_CUR(0) pattern.
264 */
265 if (whence == SEEK_END)
266 base = dmabuf->size;
267 else if (whence == SEEK_SET)
268 base = 0;
269 else
270 return -EINVAL;
271
272 if (offset != 0)
273 return -EINVAL;
274
275 return base + offset;
276}
277
278/**
279 * DOC: implicit fence polling
280 *
281 * To support cross-device and cross-driver synchronization of buffer access
282 * implicit fences (represented internally in the kernel with &struct dma_fence)
283 * can be attached to a &dma_buf. The glue for that and a few related things are
284 * provided in the &dma_resv structure.
285 *
286 * Userspace can query the state of these implicitly tracked fences using poll()
287 * and related system calls:
288 *
289 * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the
290 * most recent write or exclusive fence.
291 *
292 * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of
293 * all attached fences, shared and exclusive ones.
294 *
295 * Note that this only signals the completion of the respective fences, i.e. the
296 * DMA transfers are complete. Cache flushing and any other necessary
297 * preparations before CPU access can begin still need to happen.
298 *
299 * As an alternative to poll(), the set of fences on DMA buffer can be
300 * exported as a &sync_file using &dma_buf_sync_file_export.
301 */
302
303static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
304{
305 struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
306 struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);
307 unsigned long flags;
308
309 spin_lock_irqsave(&dcb->poll->lock, flags);
310 wake_up_locked_poll(dcb->poll, dcb->active);
311 dcb->active = 0;
312 spin_unlock_irqrestore(&dcb->poll->lock, flags);
313 dma_fence_put(fence);
314 /* Paired with get_file in dma_buf_poll */
315 fput(dmabuf->file);
316}
317
318static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
319 struct dma_buf_poll_cb_t *dcb)
320{
321 struct dma_resv_iter cursor;
322 struct dma_fence *fence;
323 int r;
324
325 dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),
326 fence) {
327 dma_fence_get(fence);
328 r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
329 if (!r)
330 return true;
331 dma_fence_put(fence);
332 }
333
334 return false;
335}
336
337static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
338{
339 struct dma_buf *dmabuf;
340 struct dma_resv *resv;
341 __poll_t events;
342
343 dmabuf = file->private_data;
344 if (!dmabuf || !dmabuf->resv)
345 return EPOLLERR;
346
347 resv = dmabuf->resv;
348
349 poll_wait(file, &dmabuf->poll, poll);
350
351 events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);
352 if (!events)
353 return 0;
354
355 dma_resv_lock(resv, NULL);
356
357 if (events & EPOLLOUT) {
358 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_out;
359
360 /* Check that callback isn't busy */
361 spin_lock_irq(&dmabuf->poll.lock);
362 if (dcb->active)
363 events &= ~EPOLLOUT;
364 else
365 dcb->active = EPOLLOUT;
366 spin_unlock_irq(&dmabuf->poll.lock);
367
368 if (events & EPOLLOUT) {
369 /* Paired with fput in dma_buf_poll_cb */
370 get_file(dmabuf->file);
371
372 if (!dma_buf_poll_add_cb(resv, true, dcb))
373 /* No callback queued, wake up any other waiters */
374 dma_buf_poll_cb(NULL, &dcb->cb);
375 else
376 events &= ~EPOLLOUT;
377 }
378 }
379
380 if (events & EPOLLIN) {
381 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_in;
382
383 /* Check that callback isn't busy */
384 spin_lock_irq(&dmabuf->poll.lock);
385 if (dcb->active)
386 events &= ~EPOLLIN;
387 else
388 dcb->active = EPOLLIN;
389 spin_unlock_irq(&dmabuf->poll.lock);
390
391 if (events & EPOLLIN) {
392 /* Paired with fput in dma_buf_poll_cb */
393 get_file(dmabuf->file);
394
395 if (!dma_buf_poll_add_cb(resv, false, dcb))
396 /* No callback queued, wake up any other waiters */
397 dma_buf_poll_cb(NULL, &dcb->cb);
398 else
399 events &= ~EPOLLIN;
400 }
401 }
402
403 dma_resv_unlock(resv);
404 return events;
405}
406
407/**
408 * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
409 * It could support changing the name of the dma-buf if the same
410 * piece of memory is used for multiple purpose between different devices.
411 *
412 * @dmabuf: [in] dmabuf buffer that will be renamed.
413 * @buf: [in] A piece of userspace memory that contains the name of
414 * the dma-buf.
415 *
416 * Returns 0 on success. If the dma-buf buffer is already attached to
417 * devices, return -EBUSY.
418 *
419 */
420static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
421{
422 char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
423
424 if (IS_ERR(name))
425 return PTR_ERR(name);
426
427 spin_lock(&dmabuf->name_lock);
428 kfree(dmabuf->name);
429 dmabuf->name = name;
430 spin_unlock(&dmabuf->name_lock);
431
432 return 0;
433}
434
435#if IS_ENABLED(CONFIG_SYNC_FILE)
436static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
437 void __user *user_data)
438{
439 struct dma_buf_export_sync_file arg;
440 enum dma_resv_usage usage;
441 struct dma_fence *fence = NULL;
442 struct sync_file *sync_file;
443 int fd, ret;
444
445 if (copy_from_user(&arg, user_data, sizeof(arg)))
446 return -EFAULT;
447
448 if (arg.flags & ~DMA_BUF_SYNC_RW)
449 return -EINVAL;
450
451 if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
452 return -EINVAL;
453
454 fd = get_unused_fd_flags(O_CLOEXEC);
455 if (fd < 0)
456 return fd;
457
458 usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE);
459 ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence);
460 if (ret)
461 goto err_put_fd;
462
463 if (!fence)
464 fence = dma_fence_get_stub();
465
466 sync_file = sync_file_create(fence);
467
468 dma_fence_put(fence);
469
470 if (!sync_file) {
471 ret = -ENOMEM;
472 goto err_put_fd;
473 }
474
475 arg.fd = fd;
476 if (copy_to_user(user_data, &arg, sizeof(arg))) {
477 ret = -EFAULT;
478 goto err_put_file;
479 }
480
481 fd_install(fd, sync_file->file);
482
483 return 0;
484
485err_put_file:
486 fput(sync_file->file);
487err_put_fd:
488 put_unused_fd(fd);
489 return ret;
490}
491
492static long dma_buf_import_sync_file(struct dma_buf *dmabuf,
493 const void __user *user_data)
494{
495 struct dma_buf_import_sync_file arg;
496 struct dma_fence *fence, *f;
497 enum dma_resv_usage usage;
498 struct dma_fence_unwrap iter;
499 unsigned int num_fences;
500 int ret = 0;
501
502 if (copy_from_user(&arg, user_data, sizeof(arg)))
503 return -EFAULT;
504
505 if (arg.flags & ~DMA_BUF_SYNC_RW)
506 return -EINVAL;
507
508 if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
509 return -EINVAL;
510
511 fence = sync_file_get_fence(arg.fd);
512 if (!fence)
513 return -EINVAL;
514
515 usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :
516 DMA_RESV_USAGE_READ;
517
518 num_fences = 0;
519 dma_fence_unwrap_for_each(f, &iter, fence)
520 ++num_fences;
521
522 if (num_fences > 0) {
523 dma_resv_lock(dmabuf->resv, NULL);
524
525 ret = dma_resv_reserve_fences(dmabuf->resv, num_fences);
526 if (!ret) {
527 dma_fence_unwrap_for_each(f, &iter, fence)
528 dma_resv_add_fence(dmabuf->resv, f, usage);
529 }
530
531 dma_resv_unlock(dmabuf->resv);
532 }
533
534 dma_fence_put(fence);
535
536 return ret;
537}
538#endif
539
540static long dma_buf_ioctl(struct file *file,
541 unsigned int cmd, unsigned long arg)
542{
543 struct dma_buf *dmabuf;
544 struct dma_buf_sync sync;
545 enum dma_data_direction direction;
546 int ret;
547
548 dmabuf = file->private_data;
549
550 switch (cmd) {
551 case DMA_BUF_IOCTL_SYNC:
552 if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
553 return -EFAULT;
554
555 if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
556 return -EINVAL;
557
558 switch (sync.flags & DMA_BUF_SYNC_RW) {
559 case DMA_BUF_SYNC_READ:
560 direction = DMA_FROM_DEVICE;
561 break;
562 case DMA_BUF_SYNC_WRITE:
563 direction = DMA_TO_DEVICE;
564 break;
565 case DMA_BUF_SYNC_RW:
566 direction = DMA_BIDIRECTIONAL;
567 break;
568 default:
569 return -EINVAL;
570 }
571
572 if (sync.flags & DMA_BUF_SYNC_END)
573 ret = dma_buf_end_cpu_access(dmabuf, direction);
574 else
575 ret = dma_buf_begin_cpu_access(dmabuf, direction);
576
577 return ret;
578
579 case DMA_BUF_SET_NAME_A:
580 case DMA_BUF_SET_NAME_B:
581 return dma_buf_set_name(dmabuf, (const char __user *)arg);
582
583#if IS_ENABLED(CONFIG_SYNC_FILE)
584 case DMA_BUF_IOCTL_EXPORT_SYNC_FILE:
585 return dma_buf_export_sync_file(dmabuf, (void __user *)arg);
586 case DMA_BUF_IOCTL_IMPORT_SYNC_FILE:
587 return dma_buf_import_sync_file(dmabuf, (const void __user *)arg);
588#endif
589
590 default:
591 return -ENOTTY;
592 }
593}
594
595static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
596{
597 struct dma_buf *dmabuf = file->private_data;
598
599 seq_printf(m, "size:\t%zu\n", dmabuf->size);
600 /* Don't count the temporary reference taken inside procfs seq_show */
601 seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
602 seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
603 spin_lock(&dmabuf->name_lock);
604 if (dmabuf->name)
605 seq_printf(m, "name:\t%s\n", dmabuf->name);
606 spin_unlock(&dmabuf->name_lock);
607}
608
609static const struct file_operations dma_buf_fops = {
610 .release = dma_buf_file_release,
611 .mmap = dma_buf_mmap_internal,
612 .llseek = dma_buf_llseek,
613 .poll = dma_buf_poll,
614 .unlocked_ioctl = dma_buf_ioctl,
615 .compat_ioctl = compat_ptr_ioctl,
616 .show_fdinfo = dma_buf_show_fdinfo,
617};
618
619/*
620 * is_dma_buf_file - Check if struct file* is associated with dma_buf
621 */
622static inline int is_dma_buf_file(struct file *file)
623{
624 return file->f_op == &dma_buf_fops;
625}
626
627static struct file *dma_buf_getfile(size_t size, int flags)
628{
629 static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);
630 struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
631 struct file *file;
632
633 if (IS_ERR(inode))
634 return ERR_CAST(inode);
635
636 inode->i_size = size;
637 inode_set_bytes(inode, size);
638
639 /*
640 * The ->i_ino acquired from get_next_ino() is not unique thus
641 * not suitable for using it as dentry name by dmabuf stats.
642 * Override ->i_ino with the unique and dmabuffs specific
643 * value.
644 */
645 inode->i_ino = atomic64_inc_return(&dmabuf_inode);
646 flags &= O_ACCMODE | O_NONBLOCK;
647 file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",
648 flags, &dma_buf_fops);
649 if (IS_ERR(file))
650 goto err_alloc_file;
651
652 return file;
653
654err_alloc_file:
655 iput(inode);
656 return file;
657}
658
659/**
660 * DOC: dma buf device access
661 *
662 * For device DMA access to a shared DMA buffer the usual sequence of operations
663 * is fairly simple:
664 *
665 * 1. The exporter defines his exporter instance using
666 * DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private
667 * buffer object into a &dma_buf. It then exports that &dma_buf to userspace
668 * as a file descriptor by calling dma_buf_fd().
669 *
670 * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
671 * to share with: First the file descriptor is converted to a &dma_buf using
672 * dma_buf_get(). Then the buffer is attached to the device using
673 * dma_buf_attach().
674 *
675 * Up to this stage the exporter is still free to migrate or reallocate the
676 * backing storage.
677 *
678 * 3. Once the buffer is attached to all devices userspace can initiate DMA
679 * access to the shared buffer. In the kernel this is done by calling
680 * dma_buf_map_attachment() and dma_buf_unmap_attachment().
681 *
682 * 4. Once a driver is done with a shared buffer it needs to call
683 * dma_buf_detach() (after cleaning up any mappings) and then release the
684 * reference acquired with dma_buf_get() by calling dma_buf_put().
685 *
686 * For the detailed semantics exporters are expected to implement see
687 * &dma_buf_ops.
688 */
689
690/**
691 * dma_buf_export - Creates a new dma_buf, and associates an anon file
692 * with this buffer, so it can be exported.
693 * Also connect the allocator specific data and ops to the buffer.
694 * Additionally, provide a name string for exporter; useful in debugging.
695 *
696 * @exp_info: [in] holds all the export related information provided
697 * by the exporter. see &struct dma_buf_export_info
698 * for further details.
699 *
700 * Returns, on success, a newly created struct dma_buf object, which wraps the
701 * supplied private data and operations for struct dma_buf_ops. On either
702 * missing ops, or error in allocating struct dma_buf, will return negative
703 * error.
704 *
705 * For most cases the easiest way to create @exp_info is through the
706 * %DEFINE_DMA_BUF_EXPORT_INFO macro.
707 */
708struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
709{
710 struct dma_buf *dmabuf;
711 struct dma_resv *resv = exp_info->resv;
712 struct file *file;
713 size_t alloc_size = sizeof(struct dma_buf);
714 int ret;
715
716 if (WARN_ON(!exp_info->priv || !exp_info->ops
717 || !exp_info->ops->map_dma_buf
718 || !exp_info->ops->unmap_dma_buf
719 || !exp_info->ops->release))
720 return ERR_PTR(-EINVAL);
721
722 if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
723 return ERR_PTR(-EINVAL);
724
725 if (!try_module_get(exp_info->owner))
726 return ERR_PTR(-ENOENT);
727
728 file = dma_buf_getfile(exp_info->size, exp_info->flags);
729 if (IS_ERR(file)) {
730 ret = PTR_ERR(file);
731 goto err_module;
732 }
733
734 if (!exp_info->resv)
735 alloc_size += sizeof(struct dma_resv);
736 else
737 /* prevent &dma_buf[1] == dma_buf->resv */
738 alloc_size += 1;
739 dmabuf = kzalloc(alloc_size, GFP_KERNEL);
740 if (!dmabuf) {
741 ret = -ENOMEM;
742 goto err_file;
743 }
744
745 dmabuf->priv = exp_info->priv;
746 dmabuf->ops = exp_info->ops;
747 dmabuf->size = exp_info->size;
748 dmabuf->exp_name = exp_info->exp_name;
749 dmabuf->owner = exp_info->owner;
750 spin_lock_init(&dmabuf->name_lock);
751 init_waitqueue_head(&dmabuf->poll);
752 dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
753 dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
754 INIT_LIST_HEAD(&dmabuf->attachments);
755
756 if (!resv) {
757 dmabuf->resv = (struct dma_resv *)&dmabuf[1];
758 dma_resv_init(dmabuf->resv);
759 } else {
760 dmabuf->resv = resv;
761 }
762
763 file->private_data = dmabuf;
764 file->f_path.dentry->d_fsdata = dmabuf;
765 dmabuf->file = file;
766
767 __dma_buf_list_add(dmabuf);
768
769 DMA_BUF_TRACE(trace_dma_buf_export, dmabuf);
770
771 return dmabuf;
772
773err_file:
774 fput(file);
775err_module:
776 module_put(exp_info->owner);
777 return ERR_PTR(ret);
778}
779EXPORT_SYMBOL_NS_GPL(dma_buf_export, "DMA_BUF");
780
781/**
782 * dma_buf_fd - returns a file descriptor for the given struct dma_buf
783 * @dmabuf: [in] pointer to dma_buf for which fd is required.
784 * @flags: [in] flags to give to fd
785 *
786 * On success, returns an associated 'fd'. Else, returns error.
787 */
788int dma_buf_fd(struct dma_buf *dmabuf, int flags)
789{
790 int fd;
791
792 if (!dmabuf || !dmabuf->file)
793 return -EINVAL;
794
795 fd = get_unused_fd_flags(flags);
796 if (fd < 0)
797 return fd;
798
799 DMA_BUF_TRACE(trace_dma_buf_fd, dmabuf, fd);
800
801 fd_install(fd, dmabuf->file);
802 return fd;
803}
804EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF");
805
806/**
807 * dma_buf_fd_install - install a reserved fd for a dma-buf
808 * @dmabuf: [in] pointer to dma_buf
809 * @fd: [in] fd reserved with get_unused_fd_flags()
810 *
811 * Publishes a previously reserved fd into the caller's fd table.
812 * Must only be called after all fallible work (e.g. copy_to_user)
813 * has succeeded, as it cannot be undone safely once called.
814 *
815 * The caller is responsible for having emitted the trace event
816 * (via dma_buf_fd() or get_unused_fd_flags() + this function)
817 * before calling this.
818 */
819void dma_buf_fd_install(struct dma_buf *dmabuf, int fd)
820{
821 DMA_BUF_TRACE(trace_dma_buf_fd, dmabuf, fd);
822 fd_install(fd, dmabuf->file);
823}
824EXPORT_SYMBOL_NS_GPL(dma_buf_fd_install, "DMA_BUF");
825
826/**
827 * dma_buf_get - returns the struct dma_buf related to an fd
828 * @fd: [in] fd associated with the struct dma_buf to be returned
829 *
830 * On success, returns the struct dma_buf associated with an fd; uses
831 * file's refcounting done by fget to increase refcount. returns ERR_PTR
832 * otherwise.
833 */
834struct dma_buf *dma_buf_get(int fd)
835{
836 struct file *file;
837 struct dma_buf *dmabuf;
838
839 file = fget(fd);
840
841 if (!file)
842 return ERR_PTR(-EBADF);
843
844 if (!is_dma_buf_file(file)) {
845 fput(file);
846 return ERR_PTR(-EINVAL);
847 }
848
849 dmabuf = file->private_data;
850
851 DMA_BUF_TRACE(trace_dma_buf_get, dmabuf, fd);
852
853 return dmabuf;
854}
855EXPORT_SYMBOL_NS_GPL(dma_buf_get, "DMA_BUF");
856
857/**
858 * dma_buf_put - decreases refcount of the buffer
859 * @dmabuf: [in] buffer to reduce refcount of
860 *
861 * Uses file's refcounting done implicitly by fput().
862 *
863 * If, as a result of this call, the refcount becomes 0, the 'release' file
864 * operation related to this fd is called. It calls &dma_buf_ops.release vfunc
865 * in turn, and frees the memory allocated for dmabuf when exported.
866 */
867void dma_buf_put(struct dma_buf *dmabuf)
868{
869 if (WARN_ON(!dmabuf || !dmabuf->file))
870 return;
871
872 DMA_BUF_TRACE(trace_dma_buf_put, dmabuf);
873 fput(dmabuf->file);
874}
875EXPORT_SYMBOL_NS_GPL(dma_buf_put, "DMA_BUF");
876
877static int dma_buf_wrap_sg_table(struct sg_table **sg_table)
878{
879 struct scatterlist *to_sg, *from_sg;
880 struct sg_table *from = *sg_table;
881 struct dma_buf_sg_table_wrapper *to;
882 int i, ret;
883
884 if (!IS_ENABLED(CONFIG_DMABUF_DEBUG))
885 return 0;
886
887 /*
888 * To catch abuse of the underlying struct page by importers copy the
889 * sg_table without copying the page_link and give only the copy back to
890 * the importer.
891 */
892 to = kzalloc_obj(*to);
893 if (!to)
894 return -ENOMEM;
895
896 ret = sg_alloc_table(&to->wrapper, from->nents, GFP_KERNEL);
897 if (ret)
898 goto free_to;
899
900 to_sg = to->wrapper.sgl;
901 for_each_sgtable_dma_sg(from, from_sg, i) {
902 to_sg->offset = 0;
903 to_sg->length = 0;
904 sg_assign_page(to_sg, NULL);
905 sg_dma_address(to_sg) = sg_dma_address(from_sg);
906 sg_dma_len(to_sg) = sg_dma_len(from_sg);
907 to_sg = sg_next(to_sg);
908 }
909
910 to->original = from;
911 *sg_table = &to->wrapper;
912 return 0;
913
914free_to:
915 kfree(to);
916 return ret;
917}
918
919static void dma_buf_unwrap_sg_table(struct sg_table **sg_table)
920{
921 struct dma_buf_sg_table_wrapper *copy;
922
923 if (!IS_ENABLED(CONFIG_DMABUF_DEBUG))
924 return;
925
926 copy = container_of(*sg_table, typeof(*copy), wrapper);
927 *sg_table = copy->original;
928 sg_free_table(&copy->wrapper);
929 kfree(copy);
930}
931
932static inline bool
933dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach)
934{
935 return !!attach->importer_ops;
936}
937
938static bool
939dma_buf_pin_on_map(struct dma_buf_attachment *attach)
940{
941 return attach->dmabuf->ops->pin &&
942 !dma_buf_attachment_is_dynamic(attach);
943}
944
945/**
946 * DOC: locking convention
947 *
948 * In order to avoid deadlock situations between dma-buf exports and importers,
949 * all dma-buf API users must follow the common dma-buf locking convention.
950 *
951 * Convention for importers
952 *
953 * 1. Importers must hold the dma-buf reservation lock when calling these
954 * functions:
955 *
956 * - dma_buf_pin()
957 * - dma_buf_unpin()
958 * - dma_buf_map_attachment()
959 * - dma_buf_unmap_attachment()
960 * - dma_buf_vmap()
961 * - dma_buf_vunmap()
962 *
963 * 2. Importers must not hold the dma-buf reservation lock when calling these
964 * functions:
965 *
966 * - dma_buf_attach()
967 * - dma_buf_dynamic_attach()
968 * - dma_buf_detach()
969 * - dma_buf_export()
970 * - dma_buf_fd()
971 * - dma_buf_get()
972 * - dma_buf_put()
973 * - dma_buf_mmap()
974 * - dma_buf_begin_cpu_access()
975 * - dma_buf_end_cpu_access()
976 * - dma_buf_map_attachment_unlocked()
977 * - dma_buf_unmap_attachment_unlocked()
978 * - dma_buf_vmap_unlocked()
979 * - dma_buf_vunmap_unlocked()
980 *
981 * Convention for exporters
982 *
983 * 1. These &dma_buf_ops callbacks are invoked with unlocked dma-buf
984 * reservation and exporter can take the lock:
985 *
986 * - &dma_buf_ops.attach()
987 * - &dma_buf_ops.detach()
988 * - &dma_buf_ops.release()
989 * - &dma_buf_ops.begin_cpu_access()
990 * - &dma_buf_ops.end_cpu_access()
991 * - &dma_buf_ops.mmap()
992 *
993 * 2. These &dma_buf_ops callbacks are invoked with locked dma-buf
994 * reservation and exporter can't take the lock:
995 *
996 * - &dma_buf_ops.pin()
997 * - &dma_buf_ops.unpin()
998 * - &dma_buf_ops.map_dma_buf()
999 * - &dma_buf_ops.unmap_dma_buf()
1000 * - &dma_buf_ops.vmap()
1001 * - &dma_buf_ops.vunmap()
1002 *
1003 * 3. Exporters must hold the dma-buf reservation lock when calling these
1004 * functions:
1005 *
1006 * - dma_buf_invalidate_mappings()
1007 */
1008
1009/**
1010 * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list
1011 * @dmabuf: [in] buffer to attach device to.
1012 * @dev: [in] device to be attached.
1013 * @importer_ops: [in] importer operations for the attachment
1014 * @importer_priv: [in] importer private pointer for the attachment
1015 *
1016 * Returns struct dma_buf_attachment pointer for this attachment. Attachments
1017 * must be cleaned up by calling dma_buf_detach().
1018 *
1019 * Optionally this calls &dma_buf_ops.attach to allow device-specific attach
1020 * functionality.
1021 *
1022 * Returns:
1023 *
1024 * A pointer to newly created &dma_buf_attachment on success, or a negative
1025 * error code wrapped into a pointer on failure.
1026 *
1027 * Note that this can fail if the backing storage of @dmabuf is in a place not
1028 * accessible to @dev, and cannot be moved to a more suitable place. This is
1029 * indicated with the error code -EBUSY.
1030 */
1031struct dma_buf_attachment *
1032dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
1033 const struct dma_buf_attach_ops *importer_ops,
1034 void *importer_priv)
1035{
1036 struct dma_buf_attachment *attach;
1037 int ret;
1038
1039 if (WARN_ON(!dmabuf || !dev))
1040 return ERR_PTR(-EINVAL);
1041
1042 attach = kzalloc_obj(*attach);
1043 if (!attach)
1044 return ERR_PTR(-ENOMEM);
1045
1046 attach->dev = dev;
1047 attach->dmabuf = dmabuf;
1048 if (importer_ops)
1049 attach->peer2peer = importer_ops->allow_peer2peer;
1050 attach->importer_ops = importer_ops;
1051 attach->importer_priv = importer_priv;
1052
1053 if (dmabuf->ops->attach) {
1054 ret = dmabuf->ops->attach(dmabuf, attach);
1055 if (ret)
1056 goto err_attach;
1057 }
1058 dma_resv_lock(dmabuf->resv, NULL);
1059 list_add(&attach->node, &dmabuf->attachments);
1060 dma_resv_unlock(dmabuf->resv);
1061
1062 DMA_BUF_TRACE(trace_dma_buf_dynamic_attach, dmabuf, attach,
1063 dma_buf_attachment_is_dynamic(attach), dev);
1064
1065 return attach;
1066
1067err_attach:
1068 kfree(attach);
1069 return ERR_PTR(ret);
1070}
1071EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, "DMA_BUF");
1072
1073/**
1074 * dma_buf_attach - Wrapper for dma_buf_dynamic_attach
1075 * @dmabuf: [in] buffer to attach device to.
1076 * @dev: [in] device to be attached.
1077 *
1078 * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static
1079 * mapping.
1080 */
1081struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
1082 struct device *dev)
1083{
1084 return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
1085}
1086EXPORT_SYMBOL_NS_GPL(dma_buf_attach, "DMA_BUF");
1087
1088/**
1089 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list
1090 * @dmabuf: [in] buffer to detach from.
1091 * @attach: [in] attachment to be detached; is free'd after this call.
1092 *
1093 * Clean up a device attachment obtained by calling dma_buf_attach().
1094 *
1095 * Optionally this calls &dma_buf_ops.detach for device-specific detach.
1096 */
1097void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
1098{
1099 if (WARN_ON(!dmabuf || !attach || dmabuf != attach->dmabuf))
1100 return;
1101
1102 dma_resv_lock(dmabuf->resv, NULL);
1103 list_del(&attach->node);
1104 dma_resv_unlock(dmabuf->resv);
1105
1106 if (dmabuf->ops->detach)
1107 dmabuf->ops->detach(dmabuf, attach);
1108
1109 DMA_BUF_TRACE(trace_dma_buf_detach, dmabuf, attach,
1110 dma_buf_attachment_is_dynamic(attach), attach->dev);
1111
1112 kfree(attach);
1113}
1114EXPORT_SYMBOL_NS_GPL(dma_buf_detach, "DMA_BUF");
1115
1116/**
1117 * dma_buf_pin - Lock down the DMA-buf
1118 * @attach: [in] attachment which should be pinned
1119 *
1120 * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may
1121 * call this, and only for limited use cases like scanout and not for temporary
1122 * pin operations. It is not permitted to allow userspace to pin arbitrary
1123 * amounts of buffers through this interface.
1124 *
1125 * Buffers must be unpinned by calling dma_buf_unpin().
1126 *
1127 * Returns:
1128 * 0 on success, negative error code on failure.
1129 */
1130int dma_buf_pin(struct dma_buf_attachment *attach)
1131{
1132 struct dma_buf *dmabuf = attach->dmabuf;
1133 int ret = 0;
1134
1135 WARN_ON(!attach->importer_ops);
1136
1137 dma_resv_assert_held(dmabuf->resv);
1138
1139 if (dmabuf->ops->pin)
1140 ret = dmabuf->ops->pin(attach);
1141
1142 return ret;
1143}
1144EXPORT_SYMBOL_NS_GPL(dma_buf_pin, "DMA_BUF");
1145
1146/**
1147 * dma_buf_unpin - Unpin a DMA-buf
1148 * @attach: [in] attachment which should be unpinned
1149 *
1150 * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move
1151 * any mapping of @attach again and inform the importer through
1152 * &dma_buf_attach_ops.invalidate_mappings.
1153 */
1154void dma_buf_unpin(struct dma_buf_attachment *attach)
1155{
1156 struct dma_buf *dmabuf = attach->dmabuf;
1157
1158 WARN_ON(!attach->importer_ops);
1159
1160 dma_resv_assert_held(dmabuf->resv);
1161
1162 if (dmabuf->ops->unpin)
1163 dmabuf->ops->unpin(attach);
1164}
1165EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, "DMA_BUF");
1166
1167/**
1168 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
1169 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
1170 * dma_buf_ops.
1171 * @attach: [in] attachment whose scatterlist is to be returned
1172 * @direction: [in] direction of DMA transfer
1173 *
1174 * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
1175 * on error. May return -EINTR if it is interrupted by a signal.
1176 *
1177 * On success, the DMA addresses and lengths in the returned scatterlist are
1178 * PAGE_SIZE aligned.
1179 *
1180 * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
1181 * the underlying backing storage is pinned for as long as a mapping exists,
1182 * therefore users/importers should not hold onto a mapping for undue amounts of
1183 * time.
1184 *
1185 * Important: Dynamic importers must wait for the exclusive fence of the struct
1186 * dma_resv attached to the DMA-BUF first.
1187 */
1188struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
1189 enum dma_data_direction direction)
1190{
1191 struct sg_table *sg_table;
1192 signed long ret;
1193
1194 might_sleep();
1195
1196 if (WARN_ON(!attach || !attach->dmabuf))
1197 return ERR_PTR(-EINVAL);
1198
1199 dma_resv_assert_held(attach->dmabuf->resv);
1200
1201 if (dma_buf_pin_on_map(attach)) {
1202 ret = attach->dmabuf->ops->pin(attach);
1203 /*
1204 * Catch exporters making buffers inaccessible even when
1205 * attachments preventing that exist.
1206 */
1207 WARN_ON_ONCE(ret == -EBUSY);
1208 if (ret)
1209 return ERR_PTR(ret);
1210 }
1211
1212 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
1213 if (!sg_table)
1214 sg_table = ERR_PTR(-ENOMEM);
1215 if (IS_ERR(sg_table))
1216 goto error_unpin;
1217
1218 /*
1219 * Importers with static attachments don't wait for fences.
1220 */
1221 if (!dma_buf_attachment_is_dynamic(attach)) {
1222 ret = dma_resv_wait_timeout(attach->dmabuf->resv,
1223 DMA_RESV_USAGE_KERNEL, true,
1224 MAX_SCHEDULE_TIMEOUT);
1225 if (ret < 0)
1226 goto error_unmap;
1227 }
1228 ret = dma_buf_wrap_sg_table(&sg_table);
1229 if (ret)
1230 goto error_unmap;
1231
1232 if (IS_ENABLED(CONFIG_DMA_API_DEBUG)) {
1233 struct scatterlist *sg;
1234 u64 addr;
1235 int len;
1236 int i;
1237
1238 for_each_sgtable_dma_sg(sg_table, sg, i) {
1239 addr = sg_dma_address(sg);
1240 len = sg_dma_len(sg);
1241 if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {
1242 pr_debug("%s: addr %llx or len %x is not page aligned!\n",
1243 __func__, addr, len);
1244 break;
1245 }
1246 }
1247 }
1248 return sg_table;
1249
1250error_unmap:
1251 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
1252 sg_table = ERR_PTR(ret);
1253
1254error_unpin:
1255 if (dma_buf_pin_on_map(attach))
1256 attach->dmabuf->ops->unpin(attach);
1257
1258 return sg_table;
1259}
1260EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, "DMA_BUF");
1261
1262/**
1263 * dma_buf_map_attachment_unlocked - Returns the scatterlist table of the attachment;
1264 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
1265 * dma_buf_ops.
1266 * @attach: [in] attachment whose scatterlist is to be returned
1267 * @direction: [in] direction of DMA transfer
1268 *
1269 * Unlocked variant of dma_buf_map_attachment().
1270 */
1271struct sg_table *
1272dma_buf_map_attachment_unlocked(struct dma_buf_attachment *attach,
1273 enum dma_data_direction direction)
1274{
1275 struct sg_table *sg_table;
1276
1277 might_sleep();
1278
1279 if (WARN_ON(!attach || !attach->dmabuf))
1280 return ERR_PTR(-EINVAL);
1281
1282 dma_resv_lock(attach->dmabuf->resv, NULL);
1283 sg_table = dma_buf_map_attachment(attach, direction);
1284 dma_resv_unlock(attach->dmabuf->resv);
1285
1286 return sg_table;
1287}
1288EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment_unlocked, "DMA_BUF");
1289
1290/**
1291 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
1292 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
1293 * dma_buf_ops.
1294 * @attach: [in] attachment to unmap buffer from
1295 * @sg_table: [in] scatterlist info of the buffer to unmap
1296 * @direction: [in] direction of DMA transfer
1297 *
1298 * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
1299 */
1300void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
1301 struct sg_table *sg_table,
1302 enum dma_data_direction direction)
1303{
1304 might_sleep();
1305
1306 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
1307 return;
1308
1309 dma_resv_assert_held(attach->dmabuf->resv);
1310
1311 dma_buf_unwrap_sg_table(&sg_table);
1312 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
1313
1314 if (dma_buf_pin_on_map(attach))
1315 attach->dmabuf->ops->unpin(attach);
1316}
1317EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, "DMA_BUF");
1318
1319/**
1320 * dma_buf_unmap_attachment_unlocked - unmaps and decreases usecount of the buffer;might
1321 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
1322 * dma_buf_ops.
1323 * @attach: [in] attachment to unmap buffer from
1324 * @sg_table: [in] scatterlist info of the buffer to unmap
1325 * @direction: [in] direction of DMA transfer
1326 *
1327 * Unlocked variant of dma_buf_unmap_attachment().
1328 */
1329void dma_buf_unmap_attachment_unlocked(struct dma_buf_attachment *attach,
1330 struct sg_table *sg_table,
1331 enum dma_data_direction direction)
1332{
1333 might_sleep();
1334
1335 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
1336 return;
1337
1338 dma_resv_lock(attach->dmabuf->resv, NULL);
1339 dma_buf_unmap_attachment(attach, sg_table, direction);
1340 dma_resv_unlock(attach->dmabuf->resv);
1341}
1342EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment_unlocked, "DMA_BUF");
1343
1344/**
1345 * dma_buf_attach_revocable - check if a DMA-buf importer implements
1346 * revoke semantics.
1347 * @attach: the DMA-buf attachment to check
1348 *
1349 * Returns true if the DMA-buf importer can support the revoke sequence
1350 * explained in dma_buf_invalidate_mappings() within bounded time. Meaning the
1351 * importer implements invalidate_mappings() and ensures that unmap is called as
1352 * a result.
1353 */
1354bool dma_buf_attach_revocable(struct dma_buf_attachment *attach)
1355{
1356 return attach->importer_ops &&
1357 attach->importer_ops->invalidate_mappings;
1358}
1359EXPORT_SYMBOL_NS_GPL(dma_buf_attach_revocable, "DMA_BUF");
1360
1361/**
1362 * dma_buf_invalidate_mappings - notify attachments that DMA-buf is moving
1363 *
1364 * @dmabuf: [in] buffer which is moving
1365 *
1366 * Informs all attachments that they need to destroy and recreate all their
1367 * mappings. If the attachment is dynamic then the dynamic importer is expected
1368 * to invalidate any caches it has of the mapping result and perform a new
1369 * mapping request before allowing HW to do any further DMA.
1370 *
1371 * If the attachment is pinned then this informs the pinned importer that the
1372 * underlying mapping is no longer available. Pinned importers may take this is
1373 * as a permanent revocation and never establish new mappings so exporters
1374 * should not trigger it lightly.
1375 *
1376 * Upon return importers may continue to access the DMA-buf memory. The caller
1377 * must do two additional waits to ensure that the memory is no longer being
1378 * accessed:
1379 *
1380 * 1) Until dma_resv_wait_timeout() retires fences the importer is allowed to
1381 * fully access the memory.
1382 * 2) Until the importer calls unmap it is allowed to speculatively
1383 * read-and-discard the memory. It must not write to the memory.
1384 *
1385 * A caller wishing to use dma_buf_invalidate_mappings() to fully stop access to
1386 * the DMA-buf must wait for both. Dynamic callers can often use just the first.
1387 *
1388 * All importers providing a invalidate_mappings() op must ensure that unmap is
1389 * called within bounded time after the op.
1390 *
1391 * Pinned importers that do not support a invalidate_mappings() op will
1392 * eventually perform unmap when they are done with the buffer, which may be an
1393 * ubounded time from calling this function. dma_buf_attach_revocable() can be
1394 * used to prevent such importers from attaching.
1395 *
1396 * Importers are free to request a new mapping in parallel as this function
1397 * returns.
1398 */
1399void dma_buf_invalidate_mappings(struct dma_buf *dmabuf)
1400{
1401 struct dma_buf_attachment *attach;
1402
1403 dma_resv_assert_held(dmabuf->resv);
1404
1405 list_for_each_entry(attach, &dmabuf->attachments, node)
1406 if (attach->importer_ops &&
1407 attach->importer_ops->invalidate_mappings)
1408 attach->importer_ops->invalidate_mappings(attach);
1409}
1410EXPORT_SYMBOL_NS_GPL(dma_buf_invalidate_mappings, "DMA_BUF");
1411
1412/**
1413 * DOC: cpu access
1414 *
1415 * There are multiple reasons for supporting CPU access to a dma buffer object:
1416 *
1417 * - Fallback operations in the kernel, for example when a device is connected
1418 * over USB and the kernel needs to shuffle the data around first before
1419 * sending it away. Cache coherency is handled by bracketing any transactions
1420 * with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
1421 * access.
1422 *
1423 * Since for most kernel internal dma-buf accesses need the entire buffer, a
1424 * vmap interface is introduced. Note that on very old 32-bit architectures
1425 * vmalloc space might be limited and result in vmap calls failing.
1426 *
1427 * Interfaces:
1428 *
1429 * .. code-block:: c
1430 *
1431 * void *dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
1432 * void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
1433 *
1434 * The vmap call can fail if there is no vmap support in the exporter, or if
1435 * it runs out of vmalloc space. Note that the dma-buf layer keeps a reference
1436 * count for all vmap access and calls down into the exporter's vmap function
1437 * only when no vmapping exists, and only unmaps it once. Protection against
1438 * concurrent vmap/vunmap calls is provided by taking the &dma_buf.lock mutex.
1439 *
1440 * - For full compatibility on the importer side with existing userspace
1441 * interfaces, which might already support mmap'ing buffers. This is needed in
1442 * many processing pipelines (e.g. feeding a software rendered image into a
1443 * hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION
1444 * framework already supported this and for DMA buffer file descriptors to
1445 * replace ION buffers mmap support was needed.
1446 *
1447 * There is no special interfaces, userspace simply calls mmap on the dma-buf
1448 * fd. But like for CPU access there's a need to bracket the actual access,
1449 * which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that
1450 * DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must
1451 * be restarted.
1452 *
1453 * Some systems might need some sort of cache coherency management e.g. when
1454 * CPU and GPU domains are being accessed through dma-buf at the same time.
1455 * To circumvent this problem there are begin/end coherency markers, that
1456 * forward directly to existing dma-buf device drivers vfunc hooks. Userspace
1457 * can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
1458 * sequence would be used like following:
1459 *
1460 * - mmap dma-buf fd
1461 * - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
1462 * to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
1463 * want (with the new data being consumed by say the GPU or the scanout
1464 * device)
1465 * - munmap once you don't need the buffer any more
1466 *
1467 * For correctness and optimal performance, it is always required to use
1468 * SYNC_START and SYNC_END before and after, respectively, when accessing the
1469 * mapped address. Userspace cannot rely on coherent access, even when there
1470 * are systems where it just works without calling these ioctls.
1471 *
1472 * - And as a CPU fallback in userspace processing pipelines.
1473 *
1474 * Similar to the motivation for kernel cpu access it is again important that
1475 * the userspace code of a given importing subsystem can use the same
1476 * interfaces with a imported dma-buf buffer object as with a native buffer
1477 * object. This is especially important for drm where the userspace part of
1478 * contemporary OpenGL, X, and other drivers is huge, and reworking them to
1479 * use a different way to mmap a buffer rather invasive.
1480 *
1481 * The assumption in the current dma-buf interfaces is that redirecting the
1482 * initial mmap is all that's needed. A survey of some of the existing
1483 * subsystems shows that no driver seems to do any nefarious thing like
1484 * syncing up with outstanding asynchronous processing on the device or
1485 * allocating special resources at fault time. So hopefully this is good
1486 * enough, since adding interfaces to intercept pagefaults and allow pte
1487 * shootdowns would increase the complexity quite a bit.
1488 *
1489 * Interface:
1490 *
1491 * .. code-block:: c
1492 *
1493 * int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, unsigned long);
1494 *
1495 * If the importing subsystem simply provides a special-purpose mmap call to
1496 * set up a mapping in userspace, calling do_mmap with &dma_buf.file will
1497 * equally achieve that for a dma-buf object.
1498 */
1499
1500static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1501 enum dma_data_direction direction)
1502{
1503 bool write = (direction == DMA_BIDIRECTIONAL ||
1504 direction == DMA_TO_DEVICE);
1505 struct dma_resv *resv = dmabuf->resv;
1506 long ret;
1507
1508 /* Wait on any implicit rendering fences */
1509 ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),
1510 true, MAX_SCHEDULE_TIMEOUT);
1511 if (ret < 0)
1512 return ret;
1513
1514 return 0;
1515}
1516
1517/**
1518 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
1519 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
1520 * preparations. Coherency is only guaranteed in the specified range for the
1521 * specified access direction.
1522 * @dmabuf: [in] buffer to prepare cpu access for.
1523 * @direction: [in] direction of access.
1524 *
1525 * After the cpu access is complete the caller should call
1526 * dma_buf_end_cpu_access(). Only when cpu access is bracketed by both calls is
1527 * it guaranteed to be coherent with other DMA access.
1528 *
1529 * This function will also wait for any DMA transactions tracked through
1530 * implicit synchronization in &dma_buf.resv. For DMA transactions with explicit
1531 * synchronization this function will only ensure cache coherency, callers must
1532 * ensure synchronization with such DMA transactions on their own.
1533 *
1534 * Can return negative error values, returns 0 on success.
1535 */
1536int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1537 enum dma_data_direction direction)
1538{
1539 int ret = 0;
1540
1541 if (WARN_ON(!dmabuf))
1542 return -EINVAL;
1543
1544 might_lock(&dmabuf->resv->lock.base);
1545
1546 if (dmabuf->ops->begin_cpu_access)
1547 ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
1548
1549 /* Ensure that all fences are waited upon - but we first allow
1550 * the native handler the chance to do so more efficiently if it
1551 * chooses. A double invocation here will be reasonably cheap no-op.
1552 */
1553 if (ret == 0)
1554 ret = __dma_buf_begin_cpu_access(dmabuf, direction);
1555
1556 return ret;
1557}
1558EXPORT_SYMBOL_NS_GPL(dma_buf_begin_cpu_access, "DMA_BUF");
1559
1560/**
1561 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
1562 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
1563 * actions. Coherency is only guaranteed in the specified range for the
1564 * specified access direction.
1565 * @dmabuf: [in] buffer to complete cpu access for.
1566 * @direction: [in] direction of access.
1567 *
1568 * This terminates CPU access started with dma_buf_begin_cpu_access().
1569 *
1570 * Can return negative error values, returns 0 on success.
1571 */
1572int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
1573 enum dma_data_direction direction)
1574{
1575 int ret = 0;
1576
1577 WARN_ON(!dmabuf);
1578
1579 might_lock(&dmabuf->resv->lock.base);
1580
1581 if (dmabuf->ops->end_cpu_access)
1582 ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
1583
1584 return ret;
1585}
1586EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, "DMA_BUF");
1587
1588
1589/**
1590 * dma_buf_mmap - Setup up a userspace mmap with the given vma
1591 * @dmabuf: [in] buffer that should back the vma
1592 * @vma: [in] vma for the mmap
1593 * @pgoff: [in] offset in pages where this mmap should start within the
1594 * dma-buf buffer.
1595 *
1596 * This function adjusts the passed in vma so that it points at the file of the
1597 * dma_buf operation. It also adjusts the starting pgoff and does bounds
1598 * checking on the size of the vma. Then it calls the exporters mmap function to
1599 * set up the mapping.
1600 *
1601 * Can return negative error values, returns 0 on success.
1602 */
1603int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
1604 unsigned long pgoff)
1605{
1606 if (WARN_ON(!dmabuf || !vma))
1607 return -EINVAL;
1608
1609 /* check if buffer supports mmap */
1610 if (!dmabuf->ops->mmap)
1611 return -EINVAL;
1612
1613 /* check for offset overflow */
1614 if (pgoff + vma_pages(vma) < pgoff)
1615 return -EOVERFLOW;
1616
1617 /* check for overflowing the buffer's size */
1618 if (pgoff + vma_pages(vma) >
1619 dmabuf->size >> PAGE_SHIFT)
1620 return -EINVAL;
1621
1622 /* readjust the vma */
1623 vma_set_file(vma, dmabuf->file);
1624 vma->vm_pgoff = pgoff;
1625
1626 DMA_BUF_TRACE(trace_dma_buf_mmap, dmabuf);
1627
1628 return dmabuf->ops->mmap(dmabuf, vma);
1629}
1630EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, "DMA_BUF");
1631
1632/**
1633 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
1634 * address space. Same restrictions as for vmap and friends apply.
1635 * @dmabuf: [in] buffer to vmap
1636 * @map: [out] returns the vmap pointer
1637 *
1638 * This call may fail due to lack of virtual mapping address space.
1639 * These calls are optional in drivers. The intended use for them
1640 * is for mapping objects linear in kernel space for high use objects.
1641 *
1642 * To ensure coherency users must call dma_buf_begin_cpu_access() and
1643 * dma_buf_end_cpu_access() around any cpu access performed through this
1644 * mapping.
1645 *
1646 * Returns 0 on success, or a negative errno code otherwise.
1647 */
1648int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
1649{
1650 struct iosys_map ptr;
1651 int ret;
1652
1653 iosys_map_clear(map);
1654
1655 if (WARN_ON(!dmabuf))
1656 return -EINVAL;
1657
1658 dma_resv_assert_held(dmabuf->resv);
1659
1660 if (!dmabuf->ops->vmap)
1661 return -EINVAL;
1662
1663 if (dmabuf->vmapping_counter) {
1664 dmabuf->vmapping_counter++;
1665 BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
1666 *map = dmabuf->vmap_ptr;
1667 return 0;
1668 }
1669
1670 BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
1671
1672 ret = dmabuf->ops->vmap(dmabuf, &ptr);
1673 if (WARN_ON_ONCE(ret))
1674 return ret;
1675
1676 dmabuf->vmap_ptr = ptr;
1677 dmabuf->vmapping_counter = 1;
1678
1679 *map = dmabuf->vmap_ptr;
1680
1681 return 0;
1682}
1683EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, "DMA_BUF");
1684
1685/**
1686 * dma_buf_vmap_unlocked - Create virtual mapping for the buffer object into kernel
1687 * address space. Same restrictions as for vmap and friends apply.
1688 * @dmabuf: [in] buffer to vmap
1689 * @map: [out] returns the vmap pointer
1690 *
1691 * Unlocked version of dma_buf_vmap()
1692 *
1693 * Returns 0 on success, or a negative errno code otherwise.
1694 */
1695int dma_buf_vmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
1696{
1697 int ret;
1698
1699 iosys_map_clear(map);
1700
1701 if (WARN_ON(!dmabuf))
1702 return -EINVAL;
1703
1704 dma_resv_lock(dmabuf->resv, NULL);
1705 ret = dma_buf_vmap(dmabuf, map);
1706 dma_resv_unlock(dmabuf->resv);
1707
1708 return ret;
1709}
1710EXPORT_SYMBOL_NS_GPL(dma_buf_vmap_unlocked, "DMA_BUF");
1711
1712/**
1713 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
1714 * @dmabuf: [in] buffer to vunmap
1715 * @map: [in] vmap pointer to vunmap
1716 */
1717void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
1718{
1719 if (WARN_ON(!dmabuf))
1720 return;
1721
1722 dma_resv_assert_held(dmabuf->resv);
1723
1724 BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
1725 BUG_ON(dmabuf->vmapping_counter == 0);
1726 BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
1727
1728 if (--dmabuf->vmapping_counter == 0) {
1729 if (dmabuf->ops->vunmap)
1730 dmabuf->ops->vunmap(dmabuf, map);
1731 iosys_map_clear(&dmabuf->vmap_ptr);
1732 }
1733}
1734EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, "DMA_BUF");
1735
1736/**
1737 * dma_buf_vunmap_unlocked - Unmap a vmap obtained by dma_buf_vmap.
1738 * @dmabuf: [in] buffer to vunmap
1739 * @map: [in] vmap pointer to vunmap
1740 */
1741void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
1742{
1743 if (WARN_ON(!dmabuf))
1744 return;
1745
1746 dma_resv_lock(dmabuf->resv, NULL);
1747 dma_buf_vunmap(dmabuf, map);
1748 dma_resv_unlock(dmabuf->resv);
1749}
1750EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, "DMA_BUF");
1751
1752#ifdef CONFIG_DEBUG_FS
1753static int dma_buf_debug_show(struct seq_file *s, void *unused)
1754{
1755 struct dma_buf *buf_obj;
1756 struct dma_buf_attachment *attach_obj;
1757 int count = 0, attach_count;
1758 size_t size = 0;
1759 int ret;
1760
1761 ret = mutex_lock_interruptible(&dmabuf_list_mutex);
1762
1763 if (ret)
1764 return ret;
1765
1766 seq_puts(s, "\nDma-buf Objects:\n");
1767 seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",
1768 "size", "flags", "mode", "count", "ino");
1769
1770 list_for_each_entry(buf_obj, &dmabuf_list, list_node) {
1771
1772 ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
1773 if (ret)
1774 goto error_unlock;
1775
1776
1777 spin_lock(&buf_obj->name_lock);
1778 seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08llu\t%s\n",
1779 buf_obj->size,
1780 buf_obj->file->f_flags, buf_obj->file->f_mode,
1781 file_count(buf_obj->file),
1782 buf_obj->exp_name,
1783 file_inode(buf_obj->file)->i_ino,
1784 buf_obj->name ?: "<none>");
1785 spin_unlock(&buf_obj->name_lock);
1786
1787 dma_resv_describe(buf_obj->resv, s);
1788
1789 seq_puts(s, "\tAttached Devices:\n");
1790 attach_count = 0;
1791
1792 list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
1793 seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
1794 attach_count++;
1795 }
1796 dma_resv_unlock(buf_obj->resv);
1797
1798 seq_printf(s, "Total %d devices attached\n\n",
1799 attach_count);
1800
1801 count++;
1802 size += buf_obj->size;
1803 }
1804
1805 seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
1806
1807 mutex_unlock(&dmabuf_list_mutex);
1808 return 0;
1809
1810error_unlock:
1811 mutex_unlock(&dmabuf_list_mutex);
1812 return ret;
1813}
1814
1815DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
1816
1817static struct dentry *dma_buf_debugfs_dir;
1818
1819static int dma_buf_init_debugfs(void)
1820{
1821 struct dentry *d;
1822 int err = 0;
1823
1824 d = debugfs_create_dir("dma_buf", NULL);
1825 if (IS_ERR(d))
1826 return PTR_ERR(d);
1827
1828 dma_buf_debugfs_dir = d;
1829
1830 d = debugfs_create_file("bufinfo", 0444, dma_buf_debugfs_dir,
1831 NULL, &dma_buf_debug_fops);
1832 if (IS_ERR(d)) {
1833 pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
1834 debugfs_remove_recursive(dma_buf_debugfs_dir);
1835 dma_buf_debugfs_dir = NULL;
1836 err = PTR_ERR(d);
1837 }
1838
1839 return err;
1840}
1841
1842static void dma_buf_uninit_debugfs(void)
1843{
1844 debugfs_remove_recursive(dma_buf_debugfs_dir);
1845}
1846#else
1847static inline int dma_buf_init_debugfs(void)
1848{
1849 return 0;
1850}
1851static inline void dma_buf_uninit_debugfs(void)
1852{
1853}
1854#endif
1855
1856static int __init dma_buf_init(void)
1857{
1858 dma_buf_mnt = kern_mount(&dma_buf_fs_type);
1859 if (IS_ERR(dma_buf_mnt))
1860 return PTR_ERR(dma_buf_mnt);
1861
1862 dma_buf_init_debugfs();
1863 return 0;
1864}
1865subsys_initcall(dma_buf_init);
1866
1867static void __exit dma_buf_deinit(void)
1868{
1869 dma_buf_uninit_debugfs();
1870 kern_unmount(dma_buf_mnt);
1871}
1872__exitcall(dma_buf_deinit);