xref: /linux/drivers/gpu/drm/drm_prime.c (revision cdd30ebb1b9f36159d66f088b61aee264e649d7a)
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 
43 MODULE_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 
88 struct 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 
drm_prime_add_buf_handle(struct drm_prime_file_private * prime_fpriv,struct dma_buf * dma_buf,uint32_t handle)96 static 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(sizeof(*member), GFP_KERNEL);
103 	if (!member)
104 		return -ENOMEM;
105 
106 	get_dma_buf(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(&member->dmabuf_rb, rb, 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(&member->handle_rb, rb, p);
138 	rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
139 
140 	return 0;
141 }
142 
drm_prime_lookup_buf_by_handle(struct drm_prime_file_private * prime_fpriv,uint32_t handle)143 static 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 
drm_prime_lookup_buf_handle(struct drm_prime_file_private * prime_fpriv,struct dma_buf * dma_buf,uint32_t * handle)164 static 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 
drm_prime_remove_buf_handle(struct drm_prime_file_private * prime_fpriv,uint32_t handle)188 void 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(member->dma_buf);
205 			kfree(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(&prime_fpriv->lock);
215 }
216 
drm_prime_init_file_private(struct drm_prime_file_private * prime_fpriv)217 void 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 
drm_prime_destroy_file_private(struct drm_prime_file_private * prime_fpriv)224 void 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  */
drm_gem_dmabuf_export(struct drm_device * dev,struct dma_buf_export_info * exp_info)242 struct 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(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 }
258 EXPORT_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  */
drm_gem_dmabuf_release(struct dma_buf * dma_buf)269 void 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 }
279 EXPORT_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  */
drm_gem_prime_fd_to_handle(struct drm_device * dev,struct drm_file * file_priv,int prime_fd,uint32_t * handle)295 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(prime_fd);
304 	if (IS_ERR(dma_buf))
305 		return PTR_ERR(dma_buf);
306 
307 	mutex_lock(&file_priv->prime.lock);
308 
309 	ret = drm_prime_lookup_buf_handle(&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(obj)) {
321 		ret = PTR_ERR(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(dma_buf);
330 	}
331 
332 	/* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
333 	ret = drm_gem_handle_create_tail(file_priv, obj, handle);
334 	drm_gem_object_put(obj);
335 	if (ret)
336 		goto out_put;
337 
338 	ret = drm_prime_add_buf_handle(&file_priv->prime,
339 			dma_buf, *handle);
340 	mutex_unlock(&file_priv->prime.lock);
341 	if (ret)
342 		goto fail;
343 
344 	dma_buf_put(dma_buf);
345 
346 	return 0;
347 
348 fail:
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(file_priv, *handle);
353 	dma_buf_put(dma_buf);
354 	return ret;
355 
356 out_unlock:
357 	mutex_unlock(&dev->object_name_lock);
358 out_put:
359 	mutex_unlock(&file_priv->prime.lock);
360 	dma_buf_put(dma_buf);
361 	return ret;
362 }
363 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
364 
drm_prime_fd_to_handle_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)365 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
366 				 struct drm_file *file_priv)
367 {
368 	struct drm_prime_handle *args = data;
369 
370 	if (dev->driver->prime_fd_to_handle) {
371 		return dev->driver->prime_fd_to_handle(dev, file_priv, args->fd,
372 						       &args->handle);
373 	}
374 
375 	return drm_gem_prime_fd_to_handle(dev, file_priv, args->fd, &args->handle);
376 }
377 
export_and_register_object(struct drm_device * dev,struct drm_gem_object * obj,uint32_t flags)378 static struct dma_buf *export_and_register_object(struct drm_device *dev,
379 						  struct drm_gem_object *obj,
380 						  uint32_t flags)
381 {
382 	struct dma_buf *dmabuf;
383 
384 	/* prevent races with concurrent gem_close. */
385 	if (obj->handle_count == 0) {
386 		dmabuf = ERR_PTR(-ENOENT);
387 		return dmabuf;
388 	}
389 
390 	if (obj->funcs && obj->funcs->export)
391 		dmabuf = obj->funcs->export(obj, flags);
392 	else
393 		dmabuf = drm_gem_prime_export(obj, flags);
394 	if (IS_ERR(dmabuf)) {
395 		/* normally the created dma-buf takes ownership of the ref,
396 		 * but if that fails then drop the ref
397 		 */
398 		return dmabuf;
399 	}
400 
401 	/*
402 	 * Note that callers do not need to clean up the export cache
403 	 * since the check for obj->handle_count guarantees that someone
404 	 * will clean it up.
405 	 */
406 	obj->dma_buf = dmabuf;
407 	get_dma_buf(obj->dma_buf);
408 
409 	return dmabuf;
410 }
411 
412 /**
413  * drm_gem_prime_handle_to_dmabuf - PRIME export function for GEM drivers
414  * @dev: dev to export the buffer from
415  * @file_priv: drm file-private structure
416  * @handle: buffer handle to export
417  * @flags: flags like DRM_CLOEXEC
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  *
424  * Unlike drm_gem_prime_handle_to_fd(), it returns the struct dma_buf it
425  * has created, without attaching it to any file descriptors.  The difference
426  * between those two is similar to that between anon_inode_getfile() and
427  * anon_inode_getfd(); insertion into descriptor table is something you
428  * can not revert if any cleanup is needed, so the descriptor-returning
429  * variants should only be used when you are past the last failure exit
430  * and the only thing left is passing the new file descriptor to userland.
431  * When all you need is the object itself or when you need to do something
432  * else that might fail, use that one instead.
433  */
drm_gem_prime_handle_to_dmabuf(struct drm_device * dev,struct drm_file * file_priv,uint32_t handle,uint32_t flags)434 struct dma_buf *drm_gem_prime_handle_to_dmabuf(struct drm_device *dev,
435 			       struct drm_file *file_priv, uint32_t handle,
436 			       uint32_t flags)
437 {
438 	struct drm_gem_object *obj;
439 	int ret = 0;
440 	struct dma_buf *dmabuf;
441 
442 	mutex_lock(&file_priv->prime.lock);
443 	obj = drm_gem_object_lookup(file_priv, handle);
444 	if (!obj)  {
445 		dmabuf = ERR_PTR(-ENOENT);
446 		goto out_unlock;
447 	}
448 
449 	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
450 	if (dmabuf) {
451 		get_dma_buf(dmabuf);
452 		goto out;
453 	}
454 
455 	mutex_lock(&dev->object_name_lock);
456 	/* re-export the original imported object */
457 	if (obj->import_attach) {
458 		dmabuf = obj->import_attach->dmabuf;
459 		get_dma_buf(dmabuf);
460 		goto out_have_obj;
461 	}
462 
463 	if (obj->dma_buf) {
464 		get_dma_buf(obj->dma_buf);
465 		dmabuf = obj->dma_buf;
466 		goto out_have_obj;
467 	}
468 
469 	dmabuf = export_and_register_object(dev, obj, flags);
470 	if (IS_ERR(dmabuf)) {
471 		/* normally the created dma-buf takes ownership of the ref,
472 		 * but if that fails then drop the ref
473 		 */
474 		mutex_unlock(&dev->object_name_lock);
475 		goto out;
476 	}
477 
478 out_have_obj:
479 	/*
480 	 * If we've exported this buffer then cheat and add it to the import list
481 	 * so we get the correct handle back. We must do this under the
482 	 * protection of dev->object_name_lock to ensure that a racing gem close
483 	 * ioctl doesn't miss to remove this buffer handle from the cache.
484 	 */
485 	ret = drm_prime_add_buf_handle(&file_priv->prime,
486 				       dmabuf, handle);
487 	mutex_unlock(&dev->object_name_lock);
488 	if (ret) {
489 		dma_buf_put(dmabuf);
490 		dmabuf = ERR_PTR(ret);
491 	}
492 out:
493 	drm_gem_object_put(obj);
494 out_unlock:
495 	mutex_unlock(&file_priv->prime.lock);
496 	return dmabuf;
497 }
498 EXPORT_SYMBOL(drm_gem_prime_handle_to_dmabuf);
499 
500 /**
501  * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
502  * @dev: dev to export the buffer from
503  * @file_priv: drm file-private structure
504  * @handle: buffer handle to export
505  * @flags: flags like DRM_CLOEXEC
506  * @prime_fd: pointer to storage for the fd id of the create dma-buf
507  *
508  * This is the PRIME export function which must be used mandatorily by GEM
509  * drivers to ensure correct lifetime management of the underlying GEM object.
510  * The actual exporting from GEM object to a dma-buf is done through the
511  * &drm_gem_object_funcs.export callback.
512  */
drm_gem_prime_handle_to_fd(struct drm_device * dev,struct drm_file * file_priv,uint32_t handle,uint32_t flags,int * prime_fd)513 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
514 			       struct drm_file *file_priv, uint32_t handle,
515 			       uint32_t flags,
516 			       int *prime_fd)
517 {
518 	struct dma_buf *dmabuf;
519 	int fd = get_unused_fd_flags(flags);
520 
521 	if (fd < 0)
522 		return fd;
523 
524 	dmabuf = drm_gem_prime_handle_to_dmabuf(dev, file_priv, handle, flags);
525 	if (IS_ERR(dmabuf)) {
526 		put_unused_fd(fd);
527 		return PTR_ERR(dmabuf);
528 	}
529 
530 	fd_install(fd, dmabuf->file);
531 	*prime_fd = fd;
532 	return 0;
533 }
534 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
535 
drm_prime_handle_to_fd_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)536 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
537 				 struct drm_file *file_priv)
538 {
539 	struct drm_prime_handle *args = data;
540 
541 	/* check flags are valid */
542 	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
543 		return -EINVAL;
544 
545 	if (dev->driver->prime_handle_to_fd) {
546 		return dev->driver->prime_handle_to_fd(dev, file_priv,
547 						       args->handle, args->flags,
548 						       &args->fd);
549 	}
550 	return drm_gem_prime_handle_to_fd(dev, file_priv, args->handle,
551 					  args->flags, &args->fd);
552 }
553 
554 /**
555  * DOC: PRIME Helpers
556  *
557  * Drivers can implement &drm_gem_object_funcs.export and
558  * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
559  * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
560  * implement dma-buf support in terms of some lower-level helpers, which are
561  * again exported for drivers to use individually:
562  *
563  * Exporting buffers
564  * ~~~~~~~~~~~~~~~~~
565  *
566  * Optional pinning of buffers is handled at dma-buf attach and detach time in
567  * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
568  * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
569  * &drm_gem_object_funcs.get_sg_table. If &drm_gem_object_funcs.get_sg_table is
570  * unimplemented, exports into another device are rejected.
571  *
572  * For kernel-internal access there's drm_gem_dmabuf_vmap() and
573  * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
574  * drm_gem_dmabuf_mmap().
575  *
576  * Note that these export helpers can only be used if the underlying backing
577  * storage is fully coherent and either permanently pinned, or it is safe to pin
578  * it indefinitely.
579  *
580  * FIXME: The underlying helper functions are named rather inconsistently.
581  *
582  * Importing buffers
583  * ~~~~~~~~~~~~~~~~~
584  *
585  * Importing dma-bufs using drm_gem_prime_import() relies on
586  * &drm_driver.gem_prime_import_sg_table.
587  *
588  * Note that similarly to the export helpers this permanently pins the
589  * underlying backing storage. Which is ok for scanout, but is not the best
590  * option for sharing lots of buffers for rendering.
591  */
592 
593 /**
594  * drm_gem_map_attach - dma_buf attach implementation for GEM
595  * @dma_buf: buffer to attach device to
596  * @attach: buffer attachment data
597  *
598  * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
599  * used as the &dma_buf_ops.attach callback. Must be used together with
600  * drm_gem_map_detach().
601  *
602  * Returns 0 on success, negative error code on failure.
603  */
drm_gem_map_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)604 int drm_gem_map_attach(struct dma_buf *dma_buf,
605 		       struct dma_buf_attachment *attach)
606 {
607 	struct drm_gem_object *obj = dma_buf->priv;
608 
609 	/*
610 	 * drm_gem_map_dma_buf() requires obj->get_sg_table(), but drivers
611 	 * that implement their own ->map_dma_buf() do not.
612 	 */
613 	if (dma_buf->ops->map_dma_buf == drm_gem_map_dma_buf &&
614 	    !obj->funcs->get_sg_table)
615 		return -ENOSYS;
616 
617 	return drm_gem_pin(obj);
618 }
619 EXPORT_SYMBOL(drm_gem_map_attach);
620 
621 /**
622  * drm_gem_map_detach - dma_buf detach implementation for GEM
623  * @dma_buf: buffer to detach from
624  * @attach: attachment to be detached
625  *
626  * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
627  * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
628  * &dma_buf_ops.detach callback.
629  */
drm_gem_map_detach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)630 void drm_gem_map_detach(struct dma_buf *dma_buf,
631 			struct dma_buf_attachment *attach)
632 {
633 	struct drm_gem_object *obj = dma_buf->priv;
634 
635 	drm_gem_unpin(obj);
636 }
637 EXPORT_SYMBOL(drm_gem_map_detach);
638 
639 /**
640  * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
641  * @attach: attachment whose scatterlist is to be returned
642  * @dir: direction of DMA transfer
643  *
644  * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
645  * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
646  * with drm_gem_unmap_dma_buf().
647  *
648  * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
649  * on error. May return -EINTR if it is interrupted by a signal.
650  */
drm_gem_map_dma_buf(struct dma_buf_attachment * attach,enum dma_data_direction dir)651 struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
652 				     enum dma_data_direction dir)
653 {
654 	struct drm_gem_object *obj = attach->dmabuf->priv;
655 	struct sg_table *sgt;
656 	int ret;
657 
658 	if (WARN_ON(dir == DMA_NONE))
659 		return ERR_PTR(-EINVAL);
660 
661 	if (WARN_ON(!obj->funcs->get_sg_table))
662 		return ERR_PTR(-ENOSYS);
663 
664 	sgt = obj->funcs->get_sg_table(obj);
665 	if (IS_ERR(sgt))
666 		return sgt;
667 
668 	ret = dma_map_sgtable(attach->dev, sgt, dir,
669 			      DMA_ATTR_SKIP_CPU_SYNC);
670 	if (ret) {
671 		sg_free_table(sgt);
672 		kfree(sgt);
673 		sgt = ERR_PTR(ret);
674 	}
675 
676 	return sgt;
677 }
678 EXPORT_SYMBOL(drm_gem_map_dma_buf);
679 
680 /**
681  * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
682  * @attach: attachment to unmap buffer from
683  * @sgt: scatterlist info of the buffer to unmap
684  * @dir: direction of DMA transfer
685  *
686  * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
687  */
drm_gem_unmap_dma_buf(struct dma_buf_attachment * attach,struct sg_table * sgt,enum dma_data_direction dir)688 void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
689 			   struct sg_table *sgt,
690 			   enum dma_data_direction dir)
691 {
692 	if (!sgt)
693 		return;
694 
695 	dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
696 	sg_free_table(sgt);
697 	kfree(sgt);
698 }
699 EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
700 
701 /**
702  * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
703  * @dma_buf: buffer to be mapped
704  * @map: the virtual address of the buffer
705  *
706  * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
707  * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
708  * The kernel virtual address is returned in map.
709  *
710  * Returns 0 on success or a negative errno code otherwise.
711  */
drm_gem_dmabuf_vmap(struct dma_buf * dma_buf,struct iosys_map * map)712 int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct iosys_map *map)
713 {
714 	struct drm_gem_object *obj = dma_buf->priv;
715 
716 	return drm_gem_vmap(obj, map);
717 }
718 EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
719 
720 /**
721  * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
722  * @dma_buf: buffer to be unmapped
723  * @map: the virtual address of the buffer
724  *
725  * Releases a kernel virtual mapping. This can be used as the
726  * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
727  */
drm_gem_dmabuf_vunmap(struct dma_buf * dma_buf,struct iosys_map * map)728 void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map)
729 {
730 	struct drm_gem_object *obj = dma_buf->priv;
731 
732 	drm_gem_vunmap(obj, map);
733 }
734 EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
735 
736 /**
737  * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
738  * @obj: GEM object
739  * @vma: Virtual address range
740  *
741  * This function sets up a userspace mapping for PRIME exported buffers using
742  * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
743  * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
744  * called to set up the mapping.
745  */
drm_gem_prime_mmap(struct drm_gem_object * obj,struct vm_area_struct * vma)746 int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
747 {
748 	struct drm_file *priv;
749 	struct file *fil;
750 	int ret;
751 
752 	/* Add the fake offset */
753 	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
754 
755 	if (obj->funcs && obj->funcs->mmap) {
756 		vma->vm_ops = obj->funcs->vm_ops;
757 
758 		drm_gem_object_get(obj);
759 		ret = obj->funcs->mmap(obj, vma);
760 		if (ret) {
761 			drm_gem_object_put(obj);
762 			return ret;
763 		}
764 		vma->vm_private_data = obj;
765 		return 0;
766 	}
767 
768 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
769 	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
770 	if (!priv || !fil) {
771 		ret = -ENOMEM;
772 		goto out;
773 	}
774 
775 	/* Used by drm_gem_mmap() to lookup the GEM object */
776 	priv->minor = obj->dev->primary;
777 	fil->private_data = priv;
778 
779 	ret = drm_vma_node_allow(&obj->vma_node, priv);
780 	if (ret)
781 		goto out;
782 
783 	ret = obj->dev->driver->fops->mmap(fil, vma);
784 
785 	drm_vma_node_revoke(&obj->vma_node, priv);
786 out:
787 	kfree(priv);
788 	kfree(fil);
789 
790 	return ret;
791 }
792 EXPORT_SYMBOL(drm_gem_prime_mmap);
793 
794 /**
795  * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
796  * @dma_buf: buffer to be mapped
797  * @vma: virtual address range
798  *
799  * Provides memory mapping for the buffer. This can be used as the
800  * &dma_buf_ops.mmap callback. It just forwards to drm_gem_prime_mmap().
801  *
802  * Returns 0 on success or a negative error code on failure.
803  */
drm_gem_dmabuf_mmap(struct dma_buf * dma_buf,struct vm_area_struct * vma)804 int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
805 {
806 	struct drm_gem_object *obj = dma_buf->priv;
807 
808 	return drm_gem_prime_mmap(obj, vma);
809 }
810 EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
811 
812 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
813 	.cache_sgt_mapping = true,
814 	.attach = drm_gem_map_attach,
815 	.detach = drm_gem_map_detach,
816 	.map_dma_buf = drm_gem_map_dma_buf,
817 	.unmap_dma_buf = drm_gem_unmap_dma_buf,
818 	.release = drm_gem_dmabuf_release,
819 	.mmap = drm_gem_dmabuf_mmap,
820 	.vmap = drm_gem_dmabuf_vmap,
821 	.vunmap = drm_gem_dmabuf_vunmap,
822 };
823 
824 /**
825  * drm_prime_pages_to_sg - converts a page array into an sg list
826  * @dev: DRM device
827  * @pages: pointer to the array of page pointers to convert
828  * @nr_pages: length of the page vector
829  *
830  * This helper creates an sg table object from a set of pages
831  * the driver is responsible for mapping the pages into the
832  * importers address space for use with dma_buf itself.
833  *
834  * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
835  */
drm_prime_pages_to_sg(struct drm_device * dev,struct page ** pages,unsigned int nr_pages)836 struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
837 				       struct page **pages, unsigned int nr_pages)
838 {
839 	struct sg_table *sg;
840 	size_t max_segment = 0;
841 	int err;
842 
843 	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
844 	if (!sg)
845 		return ERR_PTR(-ENOMEM);
846 
847 	if (dev)
848 		max_segment = dma_max_mapping_size(dev->dev);
849 	if (max_segment == 0)
850 		max_segment = UINT_MAX;
851 	err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0,
852 						(unsigned long)nr_pages << PAGE_SHIFT,
853 						max_segment, GFP_KERNEL);
854 	if (err) {
855 		kfree(sg);
856 		sg = ERR_PTR(err);
857 	}
858 	return sg;
859 }
860 EXPORT_SYMBOL(drm_prime_pages_to_sg);
861 
862 /**
863  * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
864  * @sgt: sg_table describing the buffer to check
865  *
866  * This helper calculates the contiguous size in the DMA address space
867  * of the buffer described by the provided sg_table.
868  *
869  * This is useful for implementing
870  * &drm_gem_object_funcs.gem_prime_import_sg_table.
871  */
drm_prime_get_contiguous_size(struct sg_table * sgt)872 unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
873 {
874 	dma_addr_t expected = sg_dma_address(sgt->sgl);
875 	struct scatterlist *sg;
876 	unsigned long size = 0;
877 	int i;
878 
879 	for_each_sgtable_dma_sg(sgt, sg, i) {
880 		unsigned int len = sg_dma_len(sg);
881 
882 		if (!len)
883 			break;
884 		if (sg_dma_address(sg) != expected)
885 			break;
886 		expected += len;
887 		size += len;
888 	}
889 	return size;
890 }
891 EXPORT_SYMBOL(drm_prime_get_contiguous_size);
892 
893 /**
894  * drm_gem_prime_export - helper library implementation of the export callback
895  * @obj: GEM object to export
896  * @flags: flags like DRM_CLOEXEC and DRM_RDWR
897  *
898  * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
899  * using the PRIME helpers. It is used as the default in
900  * drm_gem_prime_handle_to_fd().
901  */
drm_gem_prime_export(struct drm_gem_object * obj,int flags)902 struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
903 				     int flags)
904 {
905 	struct drm_device *dev = obj->dev;
906 	struct dma_buf_export_info exp_info = {
907 		.exp_name = KBUILD_MODNAME, /* white lie for debug */
908 		.owner = dev->driver->fops->owner,
909 		.ops = &drm_gem_prime_dmabuf_ops,
910 		.size = obj->size,
911 		.flags = flags,
912 		.priv = obj,
913 		.resv = obj->resv,
914 	};
915 
916 	return drm_gem_dmabuf_export(dev, &exp_info);
917 }
918 EXPORT_SYMBOL(drm_gem_prime_export);
919 
920 /**
921  * drm_gem_prime_import_dev - core implementation of the import callback
922  * @dev: drm_device to import into
923  * @dma_buf: dma-buf object to import
924  * @attach_dev: struct device to dma_buf attach
925  *
926  * This is the core of drm_gem_prime_import(). It's designed to be called by
927  * drivers who want to use a different device structure than &drm_device.dev for
928  * attaching via dma_buf. This function calls
929  * &drm_driver.gem_prime_import_sg_table internally.
930  *
931  * Drivers must arrange to call drm_prime_gem_destroy() from their
932  * &drm_gem_object_funcs.free hook when using this function.
933  */
drm_gem_prime_import_dev(struct drm_device * dev,struct dma_buf * dma_buf,struct device * attach_dev)934 struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
935 					    struct dma_buf *dma_buf,
936 					    struct device *attach_dev)
937 {
938 	struct dma_buf_attachment *attach;
939 	struct sg_table *sgt;
940 	struct drm_gem_object *obj;
941 	int ret;
942 
943 	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
944 		obj = dma_buf->priv;
945 		if (obj->dev == dev) {
946 			/*
947 			 * Importing dmabuf exported from our own gem increases
948 			 * refcount on gem itself instead of f_count of dmabuf.
949 			 */
950 			drm_gem_object_get(obj);
951 			return obj;
952 		}
953 	}
954 
955 	if (!dev->driver->gem_prime_import_sg_table)
956 		return ERR_PTR(-EINVAL);
957 
958 	attach = dma_buf_attach(dma_buf, attach_dev);
959 	if (IS_ERR(attach))
960 		return ERR_CAST(attach);
961 
962 	get_dma_buf(dma_buf);
963 
964 	sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
965 	if (IS_ERR(sgt)) {
966 		ret = PTR_ERR(sgt);
967 		goto fail_detach;
968 	}
969 
970 	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
971 	if (IS_ERR(obj)) {
972 		ret = PTR_ERR(obj);
973 		goto fail_unmap;
974 	}
975 
976 	obj->import_attach = attach;
977 	obj->resv = dma_buf->resv;
978 
979 	return obj;
980 
981 fail_unmap:
982 	dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
983 fail_detach:
984 	dma_buf_detach(dma_buf, attach);
985 	dma_buf_put(dma_buf);
986 
987 	return ERR_PTR(ret);
988 }
989 EXPORT_SYMBOL(drm_gem_prime_import_dev);
990 
991 /**
992  * drm_gem_prime_import - helper library implementation of the import callback
993  * @dev: drm_device to import into
994  * @dma_buf: dma-buf object to import
995  *
996  * This is the implementation of the gem_prime_import functions for GEM drivers
997  * using the PRIME helpers. Drivers can use this as their
998  * &drm_driver.gem_prime_import implementation. It is used as the default
999  * implementation in drm_gem_prime_fd_to_handle().
1000  *
1001  * Drivers must arrange to call drm_prime_gem_destroy() from their
1002  * &drm_gem_object_funcs.free hook when using this function.
1003  */
drm_gem_prime_import(struct drm_device * dev,struct dma_buf * dma_buf)1004 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
1005 					    struct dma_buf *dma_buf)
1006 {
1007 	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
1008 }
1009 EXPORT_SYMBOL(drm_gem_prime_import);
1010 
1011 /**
1012  * drm_prime_sg_to_page_array - convert an sg table into a page array
1013  * @sgt: scatter-gather table to convert
1014  * @pages: array of page pointers to store the pages in
1015  * @max_entries: size of the passed-in array
1016  *
1017  * Exports an sg table into an array of pages.
1018  *
1019  * This function is deprecated and strongly discouraged to be used.
1020  * The page array is only useful for page faults and those can corrupt fields
1021  * in the struct page if they are not handled by the exporting driver.
1022  */
drm_prime_sg_to_page_array(struct sg_table * sgt,struct page ** pages,int max_entries)1023 int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
1024 					    struct page **pages,
1025 					    int max_entries)
1026 {
1027 	struct sg_page_iter page_iter;
1028 	struct page **p = pages;
1029 
1030 	for_each_sgtable_page(sgt, &page_iter, 0) {
1031 		if (WARN_ON(p - pages >= max_entries))
1032 			return -1;
1033 		*p++ = sg_page_iter_page(&page_iter);
1034 	}
1035 	return 0;
1036 }
1037 EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1038 
1039 /**
1040  * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1041  * @sgt: scatter-gather table to convert
1042  * @addrs: array to store the dma bus address of each page
1043  * @max_entries: size of both the passed-in arrays
1044  *
1045  * Exports an sg table into an array of addresses.
1046  *
1047  * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1048  * implementation.
1049  */
drm_prime_sg_to_dma_addr_array(struct sg_table * sgt,dma_addr_t * addrs,int max_entries)1050 int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1051 				   int max_entries)
1052 {
1053 	struct sg_dma_page_iter dma_iter;
1054 	dma_addr_t *a = addrs;
1055 
1056 	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1057 		if (WARN_ON(a - addrs >= max_entries))
1058 			return -1;
1059 		*a++ = sg_page_iter_dma_address(&dma_iter);
1060 	}
1061 	return 0;
1062 }
1063 EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1064 
1065 /**
1066  * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1067  * @obj: GEM object which was created from a dma-buf
1068  * @sg: the sg-table which was pinned at import time
1069  *
1070  * This is the cleanup functions which GEM drivers need to call when they use
1071  * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1072  */
drm_prime_gem_destroy(struct drm_gem_object * obj,struct sg_table * sg)1073 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1074 {
1075 	struct dma_buf_attachment *attach;
1076 	struct dma_buf *dma_buf;
1077 
1078 	attach = obj->import_attach;
1079 	if (sg)
1080 		dma_buf_unmap_attachment_unlocked(attach, sg, DMA_BIDIRECTIONAL);
1081 	dma_buf = attach->dmabuf;
1082 	dma_buf_detach(attach->dmabuf, attach);
1083 	/* remove the reference */
1084 	dma_buf_put(dma_buf);
1085 }
1086 EXPORT_SYMBOL(drm_prime_gem_destroy);
1087