1/*
2 * Copyright © 2012 Red Hat
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 *
23 * Authors:
24 * Dave Airlie <airlied@redhat.com>
25 * Rob Clark <rob.clark@linaro.org>
26 *
27 */
28
29#include <linux/export.h>
30#include <linux/dma-buf.h>
31#include <linux/rbtree.h>
32#include <linux/module.h>
33
34#include <drm/drm.h>
35#include <drm/drm_drv.h>
36#include <drm/drm_file.h>
37#include <drm/drm_framebuffer.h>
38#include <drm/drm_gem.h>
39#include <drm/drm_prime.h>
40
41#include "drm_internal.h"
42
43MODULE_IMPORT_NS(DMA_BUF);
44
45/**
46 * DOC: overview and lifetime rules
47 *
48 * Similar to GEM global names, PRIME file descriptors are also used to share
49 * buffer objects across processes. They offer additional security: as file
50 * descriptors must be explicitly sent over UNIX domain sockets to be shared
51 * between applications, they can't be guessed like the globally unique GEM
52 * names.
53 *
54 * Drivers that support the PRIME API implement the drm_gem_object_funcs.export
55 * and &drm_driver.gem_prime_import hooks. &dma_buf_ops implementations for
56 * drivers are all individually exported for drivers which need to overwrite
57 * or reimplement some of them.
58 *
59 * Reference Counting for GEM Drivers
60 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
61 *
62 * On the export the &dma_buf holds a reference to the exported buffer object,
63 * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD
64 * IOCTL, when it first calls &drm_gem_object_funcs.export
65 * and stores the exporting GEM object in the &dma_buf.priv field. This
66 * reference needs to be released when the final reference to the &dma_buf
67 * itself is dropped and its &dma_buf_ops.release function is called. For
68 * GEM-based drivers, the &dma_buf should be exported using
69 * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release().
70 *
71 * Thus the chain of references always flows in one direction, avoiding loops:
72 * importing GEM object -> dma-buf -> exported GEM bo. A further complication
73 * are the lookup caches for import and export. These are required to guarantee
74 * that any given object will always have only one unique userspace handle. This
75 * is required to allow userspace to detect duplicated imports, since some GEM
76 * drivers do fail command submissions if a given buffer object is listed more
77 * than once. These import and export caches in &drm_prime_file_private only
78 * retain a weak reference, which is cleaned up when the corresponding object is
79 * released.
80 *
81 * Self-importing: If userspace is using PRIME as a replacement for flink then
82 * it will get a fd->handle request for a GEM object that it created. Drivers
83 * should detect this situation and return back the underlying object from the
84 * dma-buf private. For GEM based drivers this is handled in
85 * drm_gem_prime_import() already.
86 */
87
88struct drm_prime_member {
89 struct dma_buf *dma_buf;
90 uint32_t handle;
91
92 struct rb_node dmabuf_rb;
93 struct rb_node handle_rb;
94};
95
96static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
97 struct dma_buf *dma_buf, uint32_t handle)
98{
99 struct drm_prime_member *member;
100 struct rb_node **p, *rb;
101
102 member = kmalloc(size: sizeof(*member), GFP_KERNEL);
103 if (!member)
104 return -ENOMEM;
105
106 get_dma_buf(dmabuf: dma_buf);
107 member->dma_buf = dma_buf;
108 member->handle = handle;
109
110 rb = NULL;
111 p = &prime_fpriv->dmabufs.rb_node;
112 while (*p) {
113 struct drm_prime_member *pos;
114
115 rb = *p;
116 pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
117 if (dma_buf > pos->dma_buf)
118 p = &rb->rb_right;
119 else
120 p = &rb->rb_left;
121 }
122 rb_link_node(node: &member->dmabuf_rb, parent: rb, rb_link: p);
123 rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs);
124
125 rb = NULL;
126 p = &prime_fpriv->handles.rb_node;
127 while (*p) {
128 struct drm_prime_member *pos;
129
130 rb = *p;
131 pos = rb_entry(rb, struct drm_prime_member, handle_rb);
132 if (handle > pos->handle)
133 p = &rb->rb_right;
134 else
135 p = &rb->rb_left;
136 }
137 rb_link_node(node: &member->handle_rb, parent: rb, rb_link: p);
138 rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
139
140 return 0;
141}
142
143static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
144 uint32_t handle)
145{
146 struct rb_node *rb;
147
148 rb = prime_fpriv->handles.rb_node;
149 while (rb) {
150 struct drm_prime_member *member;
151
152 member = rb_entry(rb, struct drm_prime_member, handle_rb);
153 if (member->handle == handle)
154 return member->dma_buf;
155 else if (member->handle < handle)
156 rb = rb->rb_right;
157 else
158 rb = rb->rb_left;
159 }
160
161 return NULL;
162}
163
164static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
165 struct dma_buf *dma_buf,
166 uint32_t *handle)
167{
168 struct rb_node *rb;
169
170 rb = prime_fpriv->dmabufs.rb_node;
171 while (rb) {
172 struct drm_prime_member *member;
173
174 member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
175 if (member->dma_buf == dma_buf) {
176 *handle = member->handle;
177 return 0;
178 } else if (member->dma_buf < dma_buf) {
179 rb = rb->rb_right;
180 } else {
181 rb = rb->rb_left;
182 }
183 }
184
185 return -ENOENT;
186}
187
188void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv,
189 uint32_t handle)
190{
191 struct rb_node *rb;
192
193 mutex_lock(&prime_fpriv->lock);
194
195 rb = prime_fpriv->handles.rb_node;
196 while (rb) {
197 struct drm_prime_member *member;
198
199 member = rb_entry(rb, struct drm_prime_member, handle_rb);
200 if (member->handle == handle) {
201 rb_erase(&member->handle_rb, &prime_fpriv->handles);
202 rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);
203
204 dma_buf_put(dmabuf: member->dma_buf);
205 kfree(objp: member);
206 break;
207 } else if (member->handle < handle) {
208 rb = rb->rb_right;
209 } else {
210 rb = rb->rb_left;
211 }
212 }
213
214 mutex_unlock(lock: &prime_fpriv->lock);
215}
216
217void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
218{
219 mutex_init(&prime_fpriv->lock);
220 prime_fpriv->dmabufs = RB_ROOT;
221 prime_fpriv->handles = RB_ROOT;
222}
223
224void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
225{
226 /* by now drm_gem_release should've made sure the list is empty */
227 WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
228}
229
230/**
231 * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
232 * @dev: parent device for the exported dmabuf
233 * @exp_info: the export information used by dma_buf_export()
234 *
235 * This wraps dma_buf_export() for use by generic GEM drivers that are using
236 * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
237 * a reference to the &drm_device and the exported &drm_gem_object (stored in
238 * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
239 *
240 * Returns the new dmabuf.
241 */
242struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
243 struct dma_buf_export_info *exp_info)
244{
245 struct drm_gem_object *obj = exp_info->priv;
246 struct dma_buf *dma_buf;
247
248 dma_buf = dma_buf_export(exp_info);
249 if (IS_ERR(ptr: dma_buf))
250 return dma_buf;
251
252 drm_dev_get(dev);
253 drm_gem_object_get(obj);
254 dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
255
256 return dma_buf;
257}
258EXPORT_SYMBOL(drm_gem_dmabuf_export);
259
260/**
261 * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
262 * @dma_buf: buffer to be released
263 *
264 * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
265 * must use this in their &dma_buf_ops structure as the release callback.
266 * drm_gem_dmabuf_release() should be used in conjunction with
267 * drm_gem_dmabuf_export().
268 */
269void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
270{
271 struct drm_gem_object *obj = dma_buf->priv;
272 struct drm_device *dev = obj->dev;
273
274 /* drop the reference on the export fd holds */
275 drm_gem_object_put(obj);
276
277 drm_dev_put(dev);
278}
279EXPORT_SYMBOL(drm_gem_dmabuf_release);
280
281/*
282 * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
283 * @dev: drm_device to import into
284 * @file_priv: drm file-private structure
285 * @prime_fd: fd id of the dma-buf which should be imported
286 * @handle: pointer to storage for the handle of the imported buffer object
287 *
288 * This is the PRIME import function which must be used mandatorily by GEM
289 * drivers to ensure correct lifetime management of the underlying GEM object.
290 * The actual importing of GEM object from the dma-buf is done through the
291 * &drm_driver.gem_prime_import driver callback.
292 *
293 * Returns 0 on success or a negative error code on failure.
294 */
295static int drm_gem_prime_fd_to_handle(struct drm_device *dev,
296 struct drm_file *file_priv, int prime_fd,
297 uint32_t *handle)
298{
299 struct dma_buf *dma_buf;
300 struct drm_gem_object *obj;
301 int ret;
302
303 dma_buf = dma_buf_get(fd: prime_fd);
304 if (IS_ERR(ptr: dma_buf))
305 return PTR_ERR(ptr: dma_buf);
306
307 mutex_lock(&file_priv->prime.lock);
308
309 ret = drm_prime_lookup_buf_handle(prime_fpriv: &file_priv->prime,
310 dma_buf, handle);
311 if (ret == 0)
312 goto out_put;
313
314 /* never seen this one, need to import */
315 mutex_lock(&dev->object_name_lock);
316 if (dev->driver->gem_prime_import)
317 obj = dev->driver->gem_prime_import(dev, dma_buf);
318 else
319 obj = drm_gem_prime_import(dev, dma_buf);
320 if (IS_ERR(ptr: obj)) {
321 ret = PTR_ERR(ptr: obj);
322 goto out_unlock;
323 }
324
325 if (obj->dma_buf) {
326 WARN_ON(obj->dma_buf != dma_buf);
327 } else {
328 obj->dma_buf = dma_buf;
329 get_dma_buf(dmabuf: dma_buf);
330 }
331
332 /* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
333 ret = drm_gem_handle_create_tail(file_priv, obj, handlep: handle);
334 drm_gem_object_put(obj);
335 if (ret)
336 goto out_put;
337
338 ret = drm_prime_add_buf_handle(prime_fpriv: &file_priv->prime,
339 dma_buf, handle: *handle);
340 mutex_unlock(lock: &file_priv->prime.lock);
341 if (ret)
342 goto fail;
343
344 dma_buf_put(dmabuf: dma_buf);
345
346 return 0;
347
348fail:
349 /* hmm, if driver attached, we are relying on the free-object path
350 * to detach.. which seems ok..
351 */
352 drm_gem_handle_delete(filp: file_priv, handle: *handle);
353 dma_buf_put(dmabuf: dma_buf);
354 return ret;
355
356out_unlock:
357 mutex_unlock(lock: &dev->object_name_lock);
358out_put:
359 mutex_unlock(lock: &file_priv->prime.lock);
360 dma_buf_put(dmabuf: dma_buf);
361 return ret;
362}
363
364int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
365 struct drm_file *file_priv)
366{
367 struct drm_prime_handle *args = data;
368
369 if (dev->driver->prime_fd_to_handle) {
370 return dev->driver->prime_fd_to_handle(dev, file_priv, args->fd,
371 &args->handle);
372 }
373
374 return drm_gem_prime_fd_to_handle(dev, file_priv, prime_fd: args->fd, handle: &args->handle);
375}
376
377static struct dma_buf *export_and_register_object(struct drm_device *dev,
378 struct drm_gem_object *obj,
379 uint32_t flags)
380{
381 struct dma_buf *dmabuf;
382
383 /* prevent races with concurrent gem_close. */
384 if (obj->handle_count == 0) {
385 dmabuf = ERR_PTR(error: -ENOENT);
386 return dmabuf;
387 }
388
389 if (obj->funcs && obj->funcs->export)
390 dmabuf = obj->funcs->export(obj, flags);
391 else
392 dmabuf = drm_gem_prime_export(obj, flags);
393 if (IS_ERR(ptr: dmabuf)) {
394 /* normally the created dma-buf takes ownership of the ref,
395 * but if that fails then drop the ref
396 */
397 return dmabuf;
398 }
399
400 /*
401 * Note that callers do not need to clean up the export cache
402 * since the check for obj->handle_count guarantees that someone
403 * will clean it up.
404 */
405 obj->dma_buf = dmabuf;
406 get_dma_buf(dmabuf: obj->dma_buf);
407
408 return dmabuf;
409}
410
411/*
412 * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
413 * @dev: dev to export the buffer from
414 * @file_priv: drm file-private structure
415 * @handle: buffer handle to export
416 * @flags: flags like DRM_CLOEXEC
417 * @prime_fd: pointer to storage for the fd id of the create dma-buf
418 *
419 * This is the PRIME export function which must be used mandatorily by GEM
420 * drivers to ensure correct lifetime management of the underlying GEM object.
421 * The actual exporting from GEM object to a dma-buf is done through the
422 * &drm_gem_object_funcs.export callback.
423 */
424static int drm_gem_prime_handle_to_fd(struct drm_device *dev,
425 struct drm_file *file_priv, uint32_t handle,
426 uint32_t flags,
427 int *prime_fd)
428{
429 struct drm_gem_object *obj;
430 int ret = 0;
431 struct dma_buf *dmabuf;
432
433 mutex_lock(&file_priv->prime.lock);
434 obj = drm_gem_object_lookup(filp: file_priv, handle);
435 if (!obj) {
436 ret = -ENOENT;
437 goto out_unlock;
438 }
439
440 dmabuf = drm_prime_lookup_buf_by_handle(prime_fpriv: &file_priv->prime, handle);
441 if (dmabuf) {
442 get_dma_buf(dmabuf);
443 goto out_have_handle;
444 }
445
446 mutex_lock(&dev->object_name_lock);
447 /* re-export the original imported object */
448 if (obj->import_attach) {
449 dmabuf = obj->import_attach->dmabuf;
450 get_dma_buf(dmabuf);
451 goto out_have_obj;
452 }
453
454 if (obj->dma_buf) {
455 get_dma_buf(dmabuf: obj->dma_buf);
456 dmabuf = obj->dma_buf;
457 goto out_have_obj;
458 }
459
460 dmabuf = export_and_register_object(dev, obj, flags);
461 if (IS_ERR(ptr: dmabuf)) {
462 /* normally the created dma-buf takes ownership of the ref,
463 * but if that fails then drop the ref
464 */
465 ret = PTR_ERR(ptr: dmabuf);
466 mutex_unlock(lock: &dev->object_name_lock);
467 goto out;
468 }
469
470out_have_obj:
471 /*
472 * If we've exported this buffer then cheat and add it to the import list
473 * so we get the correct handle back. We must do this under the
474 * protection of dev->object_name_lock to ensure that a racing gem close
475 * ioctl doesn't miss to remove this buffer handle from the cache.
476 */
477 ret = drm_prime_add_buf_handle(prime_fpriv: &file_priv->prime,
478 dma_buf: dmabuf, handle);
479 mutex_unlock(lock: &dev->object_name_lock);
480 if (ret)
481 goto fail_put_dmabuf;
482
483out_have_handle:
484 ret = dma_buf_fd(dmabuf, flags);
485 /*
486 * We must _not_ remove the buffer from the handle cache since the newly
487 * created dma buf is already linked in the global obj->dma_buf pointer,
488 * and that is invariant as long as a userspace gem handle exists.
489 * Closing the handle will clean out the cache anyway, so we don't leak.
490 */
491 if (ret < 0) {
492 goto fail_put_dmabuf;
493 } else {
494 *prime_fd = ret;
495 ret = 0;
496 }
497
498 goto out;
499
500fail_put_dmabuf:
501 dma_buf_put(dmabuf);
502out:
503 drm_gem_object_put(obj);
504out_unlock:
505 mutex_unlock(lock: &file_priv->prime.lock);
506
507 return ret;
508}
509
510int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
511 struct drm_file *file_priv)
512{
513 struct drm_prime_handle *args = data;
514
515 /* check flags are valid */
516 if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
517 return -EINVAL;
518
519 if (dev->driver->prime_handle_to_fd) {
520 return dev->driver->prime_handle_to_fd(dev, file_priv,
521 args->handle, args->flags,
522 &args->fd);
523 }
524 return drm_gem_prime_handle_to_fd(dev, file_priv, handle: args->handle,
525 flags: args->flags, prime_fd: &args->fd);
526}
527
528/**
529 * DOC: PRIME Helpers
530 *
531 * Drivers can implement &drm_gem_object_funcs.export and
532 * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
533 * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
534 * implement dma-buf support in terms of some lower-level helpers, which are
535 * again exported for drivers to use individually:
536 *
537 * Exporting buffers
538 * ~~~~~~~~~~~~~~~~~
539 *
540 * Optional pinning of buffers is handled at dma-buf attach and detach time in
541 * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
542 * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
543 * &drm_gem_object_funcs.get_sg_table. If &drm_gem_object_funcs.get_sg_table is
544 * unimplemented, exports into another device are rejected.
545 *
546 * For kernel-internal access there's drm_gem_dmabuf_vmap() and
547 * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
548 * drm_gem_dmabuf_mmap().
549 *
550 * Note that these export helpers can only be used if the underlying backing
551 * storage is fully coherent and either permanently pinned, or it is safe to pin
552 * it indefinitely.
553 *
554 * FIXME: The underlying helper functions are named rather inconsistently.
555 *
556 * Importing buffers
557 * ~~~~~~~~~~~~~~~~~
558 *
559 * Importing dma-bufs using drm_gem_prime_import() relies on
560 * &drm_driver.gem_prime_import_sg_table.
561 *
562 * Note that similarly to the export helpers this permanently pins the
563 * underlying backing storage. Which is ok for scanout, but is not the best
564 * option for sharing lots of buffers for rendering.
565 */
566
567/**
568 * drm_gem_map_attach - dma_buf attach implementation for GEM
569 * @dma_buf: buffer to attach device to
570 * @attach: buffer attachment data
571 *
572 * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
573 * used as the &dma_buf_ops.attach callback. Must be used together with
574 * drm_gem_map_detach().
575 *
576 * Returns 0 on success, negative error code on failure.
577 */
578int drm_gem_map_attach(struct dma_buf *dma_buf,
579 struct dma_buf_attachment *attach)
580{
581 struct drm_gem_object *obj = dma_buf->priv;
582
583 if (!obj->funcs->get_sg_table)
584 return -ENOSYS;
585
586 return drm_gem_pin(obj);
587}
588EXPORT_SYMBOL(drm_gem_map_attach);
589
590/**
591 * drm_gem_map_detach - dma_buf detach implementation for GEM
592 * @dma_buf: buffer to detach from
593 * @attach: attachment to be detached
594 *
595 * Calls &drm_gem_object_funcs.pin for device specific handling. Cleans up
596 * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
597 * &dma_buf_ops.detach callback.
598 */
599void drm_gem_map_detach(struct dma_buf *dma_buf,
600 struct dma_buf_attachment *attach)
601{
602 struct drm_gem_object *obj = dma_buf->priv;
603
604 drm_gem_unpin(obj);
605}
606EXPORT_SYMBOL(drm_gem_map_detach);
607
608/**
609 * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
610 * @attach: attachment whose scatterlist is to be returned
611 * @dir: direction of DMA transfer
612 *
613 * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
614 * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
615 * with drm_gem_unmap_dma_buf().
616 *
617 * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
618 * on error. May return -EINTR if it is interrupted by a signal.
619 */
620struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
621 enum dma_data_direction dir)
622{
623 struct drm_gem_object *obj = attach->dmabuf->priv;
624 struct sg_table *sgt;
625 int ret;
626
627 if (WARN_ON(dir == DMA_NONE))
628 return ERR_PTR(error: -EINVAL);
629
630 if (WARN_ON(!obj->funcs->get_sg_table))
631 return ERR_PTR(error: -ENOSYS);
632
633 sgt = obj->funcs->get_sg_table(obj);
634 if (IS_ERR(ptr: sgt))
635 return sgt;
636
637 ret = dma_map_sgtable(dev: attach->dev, sgt, dir,
638 DMA_ATTR_SKIP_CPU_SYNC);
639 if (ret) {
640 sg_free_table(sgt);
641 kfree(objp: sgt);
642 sgt = ERR_PTR(error: ret);
643 }
644
645 return sgt;
646}
647EXPORT_SYMBOL(drm_gem_map_dma_buf);
648
649/**
650 * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
651 * @attach: attachment to unmap buffer from
652 * @sgt: scatterlist info of the buffer to unmap
653 * @dir: direction of DMA transfer
654 *
655 * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
656 */
657void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
658 struct sg_table *sgt,
659 enum dma_data_direction dir)
660{
661 if (!sgt)
662 return;
663
664 dma_unmap_sgtable(dev: attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
665 sg_free_table(sgt);
666 kfree(objp: sgt);
667}
668EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
669
670/**
671 * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
672 * @dma_buf: buffer to be mapped
673 * @map: the virtual address of the buffer
674 *
675 * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
676 * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
677 * The kernel virtual address is returned in map.
678 *
679 * Returns 0 on success or a negative errno code otherwise.
680 */
681int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct iosys_map *map)
682{
683 struct drm_gem_object *obj = dma_buf->priv;
684
685 return drm_gem_vmap(obj, map);
686}
687EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
688
689/**
690 * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
691 * @dma_buf: buffer to be unmapped
692 * @map: the virtual address of the buffer
693 *
694 * Releases a kernel virtual mapping. This can be used as the
695 * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
696 */
697void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map)
698{
699 struct drm_gem_object *obj = dma_buf->priv;
700
701 drm_gem_vunmap(obj, map);
702}
703EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
704
705/**
706 * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
707 * @obj: GEM object
708 * @vma: Virtual address range
709 *
710 * This function sets up a userspace mapping for PRIME exported buffers using
711 * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
712 * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
713 * called to set up the mapping.
714 */
715int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
716{
717 struct drm_file *priv;
718 struct file *fil;
719 int ret;
720
721 /* Add the fake offset */
722 vma->vm_pgoff += drm_vma_node_start(node: &obj->vma_node);
723
724 if (obj->funcs && obj->funcs->mmap) {
725 vma->vm_ops = obj->funcs->vm_ops;
726
727 drm_gem_object_get(obj);
728 ret = obj->funcs->mmap(obj, vma);
729 if (ret) {
730 drm_gem_object_put(obj);
731 return ret;
732 }
733 vma->vm_private_data = obj;
734 return 0;
735 }
736
737 priv = kzalloc(size: sizeof(*priv), GFP_KERNEL);
738 fil = kzalloc(size: sizeof(*fil), GFP_KERNEL);
739 if (!priv || !fil) {
740 ret = -ENOMEM;
741 goto out;
742 }
743
744 /* Used by drm_gem_mmap() to lookup the GEM object */
745 priv->minor = obj->dev->primary;
746 fil->private_data = priv;
747
748 ret = drm_vma_node_allow(node: &obj->vma_node, tag: priv);
749 if (ret)
750 goto out;
751
752 ret = obj->dev->driver->fops->mmap(fil, vma);
753
754 drm_vma_node_revoke(node: &obj->vma_node, tag: priv);
755out:
756 kfree(objp: priv);
757 kfree(objp: fil);
758
759 return ret;
760}
761EXPORT_SYMBOL(drm_gem_prime_mmap);
762
763/**
764 * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
765 * @dma_buf: buffer to be mapped
766 * @vma: virtual address range
767 *
768 * Provides memory mapping for the buffer. This can be used as the
769 * &dma_buf_ops.mmap callback. It just forwards to drm_gem_prime_mmap().
770 *
771 * Returns 0 on success or a negative error code on failure.
772 */
773int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
774{
775 struct drm_gem_object *obj = dma_buf->priv;
776
777 return drm_gem_prime_mmap(obj, vma);
778}
779EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
780
781static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
782 .cache_sgt_mapping = true,
783 .attach = drm_gem_map_attach,
784 .detach = drm_gem_map_detach,
785 .map_dma_buf = drm_gem_map_dma_buf,
786 .unmap_dma_buf = drm_gem_unmap_dma_buf,
787 .release = drm_gem_dmabuf_release,
788 .mmap = drm_gem_dmabuf_mmap,
789 .vmap = drm_gem_dmabuf_vmap,
790 .vunmap = drm_gem_dmabuf_vunmap,
791};
792
793/**
794 * drm_prime_pages_to_sg - converts a page array into an sg list
795 * @dev: DRM device
796 * @pages: pointer to the array of page pointers to convert
797 * @nr_pages: length of the page vector
798 *
799 * This helper creates an sg table object from a set of pages
800 * the driver is responsible for mapping the pages into the
801 * importers address space for use with dma_buf itself.
802 *
803 * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
804 */
805struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
806 struct page **pages, unsigned int nr_pages)
807{
808 struct sg_table *sg;
809 size_t max_segment = 0;
810 int err;
811
812 sg = kmalloc(size: sizeof(struct sg_table), GFP_KERNEL);
813 if (!sg)
814 return ERR_PTR(error: -ENOMEM);
815
816 if (dev)
817 max_segment = dma_max_mapping_size(dev: dev->dev);
818 if (max_segment == 0)
819 max_segment = UINT_MAX;
820 err = sg_alloc_table_from_pages_segment(sgt: sg, pages, n_pages: nr_pages, offset: 0,
821 size: nr_pages << PAGE_SHIFT,
822 max_segment, GFP_KERNEL);
823 if (err) {
824 kfree(objp: sg);
825 sg = ERR_PTR(error: err);
826 }
827 return sg;
828}
829EXPORT_SYMBOL(drm_prime_pages_to_sg);
830
831/**
832 * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
833 * @sgt: sg_table describing the buffer to check
834 *
835 * This helper calculates the contiguous size in the DMA address space
836 * of the buffer described by the provided sg_table.
837 *
838 * This is useful for implementing
839 * &drm_gem_object_funcs.gem_prime_import_sg_table.
840 */
841unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
842{
843 dma_addr_t expected = sg_dma_address(sgt->sgl);
844 struct scatterlist *sg;
845 unsigned long size = 0;
846 int i;
847
848 for_each_sgtable_dma_sg(sgt, sg, i) {
849 unsigned int len = sg_dma_len(sg);
850
851 if (!len)
852 break;
853 if (sg_dma_address(sg) != expected)
854 break;
855 expected += len;
856 size += len;
857 }
858 return size;
859}
860EXPORT_SYMBOL(drm_prime_get_contiguous_size);
861
862/**
863 * drm_gem_prime_export - helper library implementation of the export callback
864 * @obj: GEM object to export
865 * @flags: flags like DRM_CLOEXEC and DRM_RDWR
866 *
867 * This is the implementation of the &drm_gem_object_funcs.export functions
868 * for GEM drivers using the PRIME helpers. It is used as the default for
869 * drivers that do not set their own.
870 */
871struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
872 int flags)
873{
874 struct drm_device *dev = obj->dev;
875 struct dma_buf_export_info exp_info = {
876 .exp_name = KBUILD_MODNAME, /* white lie for debug */
877 .owner = dev->driver->fops->owner,
878 .ops = &drm_gem_prime_dmabuf_ops,
879 .size = obj->size,
880 .flags = flags,
881 .priv = obj,
882 .resv = obj->resv,
883 };
884
885 return drm_gem_dmabuf_export(dev, &exp_info);
886}
887EXPORT_SYMBOL(drm_gem_prime_export);
888
889/**
890 * drm_gem_prime_import_dev - core implementation of the import callback
891 * @dev: drm_device to import into
892 * @dma_buf: dma-buf object to import
893 * @attach_dev: struct device to dma_buf attach
894 *
895 * This is the core of drm_gem_prime_import(). It's designed to be called by
896 * drivers who want to use a different device structure than &drm_device.dev for
897 * attaching via dma_buf. This function calls
898 * &drm_driver.gem_prime_import_sg_table internally.
899 *
900 * Drivers must arrange to call drm_prime_gem_destroy() from their
901 * &drm_gem_object_funcs.free hook when using this function.
902 */
903struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
904 struct dma_buf *dma_buf,
905 struct device *attach_dev)
906{
907 struct dma_buf_attachment *attach;
908 struct sg_table *sgt;
909 struct drm_gem_object *obj;
910 int ret;
911
912 if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
913 obj = dma_buf->priv;
914 if (obj->dev == dev) {
915 /*
916 * Importing dmabuf exported from our own gem increases
917 * refcount on gem itself instead of f_count of dmabuf.
918 */
919 drm_gem_object_get(obj);
920 return obj;
921 }
922 }
923
924 if (!dev->driver->gem_prime_import_sg_table)
925 return ERR_PTR(error: -EINVAL);
926
927 attach = dma_buf_attach(dmabuf: dma_buf, dev: attach_dev);
928 if (IS_ERR(ptr: attach))
929 return ERR_CAST(ptr: attach);
930
931 get_dma_buf(dmabuf: dma_buf);
932
933 sgt = dma_buf_map_attachment_unlocked(attach, direction: DMA_BIDIRECTIONAL);
934 if (IS_ERR(ptr: sgt)) {
935 ret = PTR_ERR(ptr: sgt);
936 goto fail_detach;
937 }
938
939 obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
940 if (IS_ERR(ptr: obj)) {
941 ret = PTR_ERR(ptr: obj);
942 goto fail_unmap;
943 }
944
945 obj->import_attach = attach;
946 obj->resv = dma_buf->resv;
947
948 return obj;
949
950fail_unmap:
951 dma_buf_unmap_attachment_unlocked(attach, sg_table: sgt, direction: DMA_BIDIRECTIONAL);
952fail_detach:
953 dma_buf_detach(dmabuf: dma_buf, attach);
954 dma_buf_put(dmabuf: dma_buf);
955
956 return ERR_PTR(error: ret);
957}
958EXPORT_SYMBOL(drm_gem_prime_import_dev);
959
960/**
961 * drm_gem_prime_import - helper library implementation of the import callback
962 * @dev: drm_device to import into
963 * @dma_buf: dma-buf object to import
964 *
965 * This is the implementation of the gem_prime_import functions for GEM
966 * drivers using the PRIME helpers. It is the default for drivers that do
967 * not set their own &drm_driver.gem_prime_import.
968 *
969 * Drivers must arrange to call drm_prime_gem_destroy() from their
970 * &drm_gem_object_funcs.free hook when using this function.
971 */
972struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
973 struct dma_buf *dma_buf)
974{
975 return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
976}
977EXPORT_SYMBOL(drm_gem_prime_import);
978
979/**
980 * drm_prime_sg_to_page_array - convert an sg table into a page array
981 * @sgt: scatter-gather table to convert
982 * @pages: array of page pointers to store the pages in
983 * @max_entries: size of the passed-in array
984 *
985 * Exports an sg table into an array of pages.
986 *
987 * This function is deprecated and strongly discouraged to be used.
988 * The page array is only useful for page faults and those can corrupt fields
989 * in the struct page if they are not handled by the exporting driver.
990 */
991int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
992 struct page **pages,
993 int max_entries)
994{
995 struct sg_page_iter page_iter;
996 struct page **p = pages;
997
998 for_each_sgtable_page(sgt, &page_iter, 0) {
999 if (WARN_ON(p - pages >= max_entries))
1000 return -1;
1001 *p++ = sg_page_iter_page(piter: &page_iter);
1002 }
1003 return 0;
1004}
1005EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1006
1007/**
1008 * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1009 * @sgt: scatter-gather table to convert
1010 * @addrs: array to store the dma bus address of each page
1011 * @max_entries: size of both the passed-in arrays
1012 *
1013 * Exports an sg table into an array of addresses.
1014 *
1015 * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1016 * implementation.
1017 */
1018int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1019 int max_entries)
1020{
1021 struct sg_dma_page_iter dma_iter;
1022 dma_addr_t *a = addrs;
1023
1024 for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1025 if (WARN_ON(a - addrs >= max_entries))
1026 return -1;
1027 *a++ = sg_page_iter_dma_address(dma_iter: &dma_iter);
1028 }
1029 return 0;
1030}
1031EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1032
1033/**
1034 * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1035 * @obj: GEM object which was created from a dma-buf
1036 * @sg: the sg-table which was pinned at import time
1037 *
1038 * This is the cleanup functions which GEM drivers need to call when they use
1039 * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1040 */
1041void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1042{
1043 struct dma_buf_attachment *attach;
1044 struct dma_buf *dma_buf;
1045
1046 attach = obj->import_attach;
1047 if (sg)
1048 dma_buf_unmap_attachment_unlocked(attach, sg_table: sg, direction: DMA_BIDIRECTIONAL);
1049 dma_buf = attach->dmabuf;
1050 dma_buf_detach(dmabuf: attach->dmabuf, attach);
1051 /* remove the reference */
1052 dma_buf_put(dmabuf: dma_buf);
1053}
1054EXPORT_SYMBOL(drm_prime_gem_destroy);
1055

source code of linux/drivers/gpu/drm/drm_prime.c