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
55  * &drm_driver.prime_handle_to_fd and &drm_driver.prime_fd_to_handle operations.
56  * GEM based drivers must use drm_gem_prime_handle_to_fd() and
57  * drm_gem_prime_fd_to_handle() to implement these. For GEM based drivers the
58  * actual driver interfaces is provided through the &drm_gem_object_funcs.export
59  * and &drm_driver.gem_prime_import hooks.
60  *
61  * &dma_buf_ops implementations for GEM drivers are all individually exported
62  * for drivers which need to overwrite or reimplement some of them.
63  *
64  * Reference Counting for GEM Drivers
65  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
66  *
67  * On the export the &dma_buf holds a reference to the exported buffer object,
68  * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD
69  * IOCTL, when it first calls &drm_gem_object_funcs.export
70  * and stores the exporting GEM object in the &dma_buf.priv field. This
71  * reference needs to be released when the final reference to the &dma_buf
72  * itself is dropped and its &dma_buf_ops.release function is called.  For
73  * GEM-based drivers, the &dma_buf should be exported using
74  * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release().
75  *
76  * Thus the chain of references always flows in one direction, avoiding loops:
77  * importing GEM object -> dma-buf -> exported GEM bo. A further complication
78  * are the lookup caches for import and export. These are required to guarantee
79  * that any given object will always have only one unique userspace handle. This
80  * is required to allow userspace to detect duplicated imports, since some GEM
81  * drivers do fail command submissions if a given buffer object is listed more
82  * than once. These import and export caches in &drm_prime_file_private only
83  * retain a weak reference, which is cleaned up when the corresponding object is
84  * released.
85  *
86  * Self-importing: If userspace is using PRIME as a replacement for flink then
87  * it will get a fd->handle request for a GEM object that it created.  Drivers
88  * should detect this situation and return back the underlying object from the
89  * dma-buf private. For GEM based drivers this is handled in
90  * drm_gem_prime_import() already.
91  */
92 
93 struct drm_prime_member {
94 	struct dma_buf *dma_buf;
95 	uint32_t handle;
96 
97 	struct rb_node dmabuf_rb;
98 	struct rb_node handle_rb;
99 };
100 
drm_prime_add_buf_handle(struct drm_prime_file_private * prime_fpriv,struct dma_buf * dma_buf,uint32_t handle)101 static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
102 				    struct dma_buf *dma_buf, uint32_t handle)
103 {
104 	struct drm_prime_member *member;
105 	struct rb_node **p, *rb;
106 
107 	member = kmalloc(sizeof(*member), GFP_KERNEL);
108 	if (!member)
109 		return -ENOMEM;
110 
111 	get_dma_buf(dma_buf);
112 	member->dma_buf = dma_buf;
113 	member->handle = handle;
114 
115 	rb = NULL;
116 	p = &prime_fpriv->dmabufs.rb_node;
117 	while (*p) {
118 		struct drm_prime_member *pos;
119 
120 		rb = *p;
121 		pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
122 		if (dma_buf > pos->dma_buf)
123 			p = &rb->rb_right;
124 		else
125 			p = &rb->rb_left;
126 	}
127 	rb_link_node(&member->dmabuf_rb, rb, p);
128 	rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs);
129 
130 	rb = NULL;
131 	p = &prime_fpriv->handles.rb_node;
132 	while (*p) {
133 		struct drm_prime_member *pos;
134 
135 		rb = *p;
136 		pos = rb_entry(rb, struct drm_prime_member, handle_rb);
137 		if (handle > pos->handle)
138 			p = &rb->rb_right;
139 		else
140 			p = &rb->rb_left;
141 	}
142 	rb_link_node(&member->handle_rb, rb, p);
143 	rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
144 
145 	return 0;
146 }
147 
drm_prime_lookup_buf_by_handle(struct drm_prime_file_private * prime_fpriv,uint32_t handle)148 static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
149 						      uint32_t handle)
150 {
151 	struct rb_node *rb;
152 
153 	rb = prime_fpriv->handles.rb_node;
154 	while (rb) {
155 		struct drm_prime_member *member;
156 
157 		member = rb_entry(rb, struct drm_prime_member, handle_rb);
158 		if (member->handle == handle)
159 			return member->dma_buf;
160 		else if (member->handle < handle)
161 			rb = rb->rb_right;
162 		else
163 			rb = rb->rb_left;
164 	}
165 
166 	return NULL;
167 }
168 
drm_prime_lookup_buf_handle(struct drm_prime_file_private * prime_fpriv,struct dma_buf * dma_buf,uint32_t * handle)169 static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
170 				       struct dma_buf *dma_buf,
171 				       uint32_t *handle)
172 {
173 	struct rb_node *rb;
174 
175 	rb = prime_fpriv->dmabufs.rb_node;
176 	while (rb) {
177 		struct drm_prime_member *member;
178 
179 		member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
180 		if (member->dma_buf == dma_buf) {
181 			*handle = member->handle;
182 			return 0;
183 		} else if (member->dma_buf < dma_buf) {
184 			rb = rb->rb_right;
185 		} else {
186 			rb = rb->rb_left;
187 		}
188 	}
189 
190 	return -ENOENT;
191 }
192 
drm_prime_remove_buf_handle(struct drm_prime_file_private * prime_fpriv,uint32_t handle)193 void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv,
194 				 uint32_t handle)
195 {
196 	struct rb_node *rb;
197 
198 	mutex_lock(&prime_fpriv->lock);
199 
200 	rb = prime_fpriv->handles.rb_node;
201 	while (rb) {
202 		struct drm_prime_member *member;
203 
204 		member = rb_entry(rb, struct drm_prime_member, handle_rb);
205 		if (member->handle == handle) {
206 			rb_erase(&member->handle_rb, &prime_fpriv->handles);
207 			rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);
208 
209 			dma_buf_put(member->dma_buf);
210 			kfree(member);
211 			break;
212 		} else if (member->handle < handle) {
213 			rb = rb->rb_right;
214 		} else {
215 			rb = rb->rb_left;
216 		}
217 	}
218 
219 	mutex_unlock(&prime_fpriv->lock);
220 }
221 
drm_prime_init_file_private(struct drm_prime_file_private * prime_fpriv)222 void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
223 {
224 	mutex_init(&prime_fpriv->lock);
225 	prime_fpriv->dmabufs = RB_ROOT;
226 	prime_fpriv->handles = RB_ROOT;
227 }
228 
drm_prime_destroy_file_private(struct drm_prime_file_private * prime_fpriv)229 void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
230 {
231 	/* by now drm_gem_release should've made sure the list is empty */
232 	WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
233 }
234 
235 /**
236  * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
237  * @dev: parent device for the exported dmabuf
238  * @exp_info: the export information used by dma_buf_export()
239  *
240  * This wraps dma_buf_export() for use by generic GEM drivers that are using
241  * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
242  * a reference to the &drm_device and the exported &drm_gem_object (stored in
243  * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
244  *
245  * Returns the new dmabuf.
246  */
drm_gem_dmabuf_export(struct drm_device * dev,struct dma_buf_export_info * exp_info)247 struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
248 				      struct dma_buf_export_info *exp_info)
249 {
250 	struct drm_gem_object *obj = exp_info->priv;
251 	struct dma_buf *dma_buf;
252 
253 	dma_buf = dma_buf_export(exp_info);
254 	if (IS_ERR(dma_buf))
255 		return dma_buf;
256 
257 	drm_dev_get(dev);
258 	drm_gem_object_get(obj);
259 	dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
260 
261 	return dma_buf;
262 }
263 EXPORT_SYMBOL(drm_gem_dmabuf_export);
264 
265 /**
266  * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
267  * @dma_buf: buffer to be released
268  *
269  * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
270  * must use this in their &dma_buf_ops structure as the release callback.
271  * drm_gem_dmabuf_release() should be used in conjunction with
272  * drm_gem_dmabuf_export().
273  */
drm_gem_dmabuf_release(struct dma_buf * dma_buf)274 void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
275 {
276 	struct drm_gem_object *obj = dma_buf->priv;
277 	struct drm_device *dev = obj->dev;
278 
279 	/* drop the reference on the export fd holds */
280 	drm_gem_object_put(obj);
281 
282 	drm_dev_put(dev);
283 }
284 EXPORT_SYMBOL(drm_gem_dmabuf_release);
285 
286 /**
287  * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
288  * @dev: dev to export the buffer from
289  * @file_priv: drm file-private structure
290  * @prime_fd: fd id of the dma-buf which should be imported
291  * @handle: pointer to storage for the handle of the imported buffer object
292  *
293  * This is the PRIME import function which must be used mandatorily by GEM
294  * drivers to ensure correct lifetime management of the underlying GEM object.
295  * The actual importing of GEM object from the dma-buf is done through the
296  * &drm_driver.gem_prime_import driver callback.
297  *
298  * Returns 0 on success or a negative error code on failure.
299  */
drm_gem_prime_fd_to_handle(struct drm_device * dev,struct drm_file * file_priv,int prime_fd,uint32_t * handle)300 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
301 			       struct drm_file *file_priv, int prime_fd,
302 			       uint32_t *handle)
303 {
304 	struct dma_buf *dma_buf;
305 	struct drm_gem_object *obj;
306 	int ret;
307 
308 	dma_buf = dma_buf_get(prime_fd);
309 	if (IS_ERR(dma_buf))
310 		return PTR_ERR(dma_buf);
311 
312 	mutex_lock(&file_priv->prime.lock);
313 
314 	ret = drm_prime_lookup_buf_handle(&file_priv->prime,
315 			dma_buf, handle);
316 	if (ret == 0)
317 		goto out_put;
318 
319 	/* never seen this one, need to import */
320 	mutex_lock(&dev->object_name_lock);
321 	if (dev->driver->gem_prime_import)
322 		obj = dev->driver->gem_prime_import(dev, dma_buf);
323 	else
324 		obj = drm_gem_prime_import(dev, dma_buf);
325 	if (IS_ERR(obj)) {
326 		ret = PTR_ERR(obj);
327 		goto out_unlock;
328 	}
329 
330 	if (obj->dma_buf) {
331 		WARN_ON(obj->dma_buf != dma_buf);
332 	} else {
333 		obj->dma_buf = dma_buf;
334 		get_dma_buf(dma_buf);
335 	}
336 
337 	/* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
338 	ret = drm_gem_handle_create_tail(file_priv, obj, handle);
339 	drm_gem_object_put(obj);
340 	if (ret)
341 		goto out_put;
342 
343 	ret = drm_prime_add_buf_handle(&file_priv->prime,
344 			dma_buf, *handle);
345 	mutex_unlock(&file_priv->prime.lock);
346 	if (ret)
347 		goto fail;
348 
349 	dma_buf_put(dma_buf);
350 
351 	return 0;
352 
353 fail:
354 	/* hmm, if driver attached, we are relying on the free-object path
355 	 * to detach.. which seems ok..
356 	 */
357 	drm_gem_handle_delete(file_priv, *handle);
358 	dma_buf_put(dma_buf);
359 	return ret;
360 
361 out_unlock:
362 	mutex_unlock(&dev->object_name_lock);
363 out_put:
364 	mutex_unlock(&file_priv->prime.lock);
365 	dma_buf_put(dma_buf);
366 	return ret;
367 }
368 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
369 
drm_prime_fd_to_handle_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)370 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
371 				 struct drm_file *file_priv)
372 {
373 	struct drm_prime_handle *args = data;
374 
375 	if (!dev->driver->prime_fd_to_handle)
376 		return -ENOSYS;
377 
378 	return dev->driver->prime_fd_to_handle(dev, file_priv,
379 			args->fd, &args->handle);
380 }
381 
export_and_register_object(struct drm_device * dev,struct drm_gem_object * obj,uint32_t flags)382 static struct dma_buf *export_and_register_object(struct drm_device *dev,
383 						  struct drm_gem_object *obj,
384 						  uint32_t flags)
385 {
386 	struct dma_buf *dmabuf;
387 
388 	/* prevent races with concurrent gem_close. */
389 	if (obj->handle_count == 0) {
390 		dmabuf = ERR_PTR(-ENOENT);
391 		return dmabuf;
392 	}
393 
394 	if (obj->funcs && obj->funcs->export)
395 		dmabuf = obj->funcs->export(obj, flags);
396 	else
397 		dmabuf = drm_gem_prime_export(obj, flags);
398 	if (IS_ERR(dmabuf)) {
399 		/* normally the created dma-buf takes ownership of the ref,
400 		 * but if that fails then drop the ref
401 		 */
402 		return dmabuf;
403 	}
404 
405 	/*
406 	 * Note that callers do not need to clean up the export cache
407 	 * since the check for obj->handle_count guarantees that someone
408 	 * will clean it up.
409 	 */
410 	obj->dma_buf = dmabuf;
411 	get_dma_buf(obj->dma_buf);
412 
413 	return dmabuf;
414 }
415 
416 /**
417  * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
418  * @dev: dev to export the buffer from
419  * @file_priv: drm file-private structure
420  * @handle: buffer handle to export
421  * @flags: flags like DRM_CLOEXEC
422  * @prime_fd: pointer to storage for the fd id of the create dma-buf
423  *
424  * This is the PRIME export function which must be used mandatorily by GEM
425  * drivers to ensure correct lifetime management of the underlying GEM object.
426  * The actual exporting from GEM object to a dma-buf is done through the
427  * &drm_gem_object_funcs.export callback.
428  */
drm_gem_prime_handle_to_fd(struct drm_device * dev,struct drm_file * file_priv,uint32_t handle,uint32_t flags,int * prime_fd)429 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
430 			       struct drm_file *file_priv, uint32_t handle,
431 			       uint32_t flags,
432 			       int *prime_fd)
433 {
434 	struct drm_gem_object *obj;
435 	int ret = 0;
436 	struct dma_buf *dmabuf;
437 
438 	mutex_lock(&file_priv->prime.lock);
439 	obj = drm_gem_object_lookup(file_priv, handle);
440 	if (!obj)  {
441 		ret = -ENOENT;
442 		goto out_unlock;
443 	}
444 
445 	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
446 	if (dmabuf) {
447 		get_dma_buf(dmabuf);
448 		goto out_have_handle;
449 	}
450 
451 	mutex_lock(&dev->object_name_lock);
452 	/* re-export the original imported object */
453 	if (obj->import_attach) {
454 		dmabuf = obj->import_attach->dmabuf;
455 		get_dma_buf(dmabuf);
456 		goto out_have_obj;
457 	}
458 
459 	if (obj->dma_buf) {
460 		get_dma_buf(obj->dma_buf);
461 		dmabuf = obj->dma_buf;
462 		goto out_have_obj;
463 	}
464 
465 	dmabuf = export_and_register_object(dev, obj, flags);
466 	if (IS_ERR(dmabuf)) {
467 		/* normally the created dma-buf takes ownership of the ref,
468 		 * but if that fails then drop the ref
469 		 */
470 		ret = PTR_ERR(dmabuf);
471 		mutex_unlock(&dev->object_name_lock);
472 		goto out;
473 	}
474 
475 out_have_obj:
476 	/*
477 	 * If we've exported this buffer then cheat and add it to the import list
478 	 * so we get the correct handle back. We must do this under the
479 	 * protection of dev->object_name_lock to ensure that a racing gem close
480 	 * ioctl doesn't miss to remove this buffer handle from the cache.
481 	 */
482 	ret = drm_prime_add_buf_handle(&file_priv->prime,
483 				       dmabuf, handle);
484 	mutex_unlock(&dev->object_name_lock);
485 	if (ret)
486 		goto fail_put_dmabuf;
487 
488 out_have_handle:
489 	ret = dma_buf_fd(dmabuf, flags);
490 	/*
491 	 * We must _not_ remove the buffer from the handle cache since the newly
492 	 * created dma buf is already linked in the global obj->dma_buf pointer,
493 	 * and that is invariant as long as a userspace gem handle exists.
494 	 * Closing the handle will clean out the cache anyway, so we don't leak.
495 	 */
496 	if (ret < 0) {
497 		goto fail_put_dmabuf;
498 	} else {
499 		*prime_fd = ret;
500 		ret = 0;
501 	}
502 
503 	goto out;
504 
505 fail_put_dmabuf:
506 	dma_buf_put(dmabuf);
507 out:
508 	drm_gem_object_put(obj);
509 out_unlock:
510 	mutex_unlock(&file_priv->prime.lock);
511 
512 	return ret;
513 }
514 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
515 
drm_prime_handle_to_fd_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)516 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
517 				 struct drm_file *file_priv)
518 {
519 	struct drm_prime_handle *args = data;
520 
521 	if (!dev->driver->prime_handle_to_fd)
522 		return -ENOSYS;
523 
524 	/* check flags are valid */
525 	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
526 		return -EINVAL;
527 
528 	return dev->driver->prime_handle_to_fd(dev, file_priv,
529 			args->handle, args->flags, &args->fd);
530 }
531 
532 /**
533  * DOC: PRIME Helpers
534  *
535  * Drivers can implement &drm_gem_object_funcs.export and
536  * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
537  * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
538  * implement dma-buf support in terms of some lower-level helpers, which are
539  * again exported for drivers to use individually:
540  *
541  * Exporting buffers
542  * ~~~~~~~~~~~~~~~~~
543  *
544  * Optional pinning of buffers is handled at dma-buf attach and detach time in
545  * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
546  * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
547  * &drm_gem_object_funcs.get_sg_table.
548  *
549  * For kernel-internal access there's drm_gem_dmabuf_vmap() and
550  * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
551  * drm_gem_dmabuf_mmap().
552  *
553  * Note that these export helpers can only be used if the underlying backing
554  * storage is fully coherent and either permanently pinned, or it is safe to pin
555  * it indefinitely.
556  *
557  * FIXME: The underlying helper functions are named rather inconsistently.
558  *
559  * Importing buffers
560  * ~~~~~~~~~~~~~~~~~
561  *
562  * Importing dma-bufs using drm_gem_prime_import() relies on
563  * &drm_driver.gem_prime_import_sg_table.
564  *
565  * Note that similarly to the export helpers this permanently pins the
566  * underlying backing storage. Which is ok for scanout, but is not the best
567  * option for sharing lots of buffers for rendering.
568  */
569 
570 /**
571  * drm_gem_map_attach - dma_buf attach implementation for GEM
572  * @dma_buf: buffer to attach device to
573  * @attach: buffer attachment data
574  *
575  * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
576  * used as the &dma_buf_ops.attach callback. Must be used together with
577  * drm_gem_map_detach().
578  *
579  * Returns 0 on success, negative error code on failure.
580  */
drm_gem_map_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)581 int drm_gem_map_attach(struct dma_buf *dma_buf,
582 		       struct dma_buf_attachment *attach)
583 {
584 	struct drm_gem_object *obj = dma_buf->priv;
585 
586 	return drm_gem_pin(obj);
587 }
588 EXPORT_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  */
drm_gem_map_detach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)599 void 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 }
606 EXPORT_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  */
drm_gem_map_dma_buf(struct dma_buf_attachment * attach,enum dma_data_direction dir)620 struct 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(-EINVAL);
629 
630 	if (WARN_ON(!obj->funcs->get_sg_table))
631 		return ERR_PTR(-ENOSYS);
632 
633 	sgt = obj->funcs->get_sg_table(obj);
634 	if (IS_ERR(sgt))
635 		return sgt;
636 
637 	ret = dma_map_sgtable(attach->dev, sgt, dir,
638 			      DMA_ATTR_SKIP_CPU_SYNC);
639 	if (ret) {
640 		sg_free_table(sgt);
641 		kfree(sgt);
642 		sgt = ERR_PTR(ret);
643 	}
644 
645 	return sgt;
646 }
647 EXPORT_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  */
drm_gem_unmap_dma_buf(struct dma_buf_attachment * attach,struct sg_table * sgt,enum dma_data_direction dir)657 void 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(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
665 	sg_free_table(sgt);
666 	kfree(sgt);
667 }
668 EXPORT_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  */
drm_gem_dmabuf_vmap(struct dma_buf * dma_buf,struct iosys_map * map)681 int 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 }
687 EXPORT_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  */
drm_gem_dmabuf_vunmap(struct dma_buf * dma_buf,struct iosys_map * map)697 void 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 }
703 EXPORT_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  *
715  * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
716  */
drm_gem_prime_mmap(struct drm_gem_object * obj,struct vm_area_struct * vma)717 int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
718 {
719 	struct drm_file *priv;
720 	struct file *fil;
721 	int ret;
722 
723 	/* Add the fake offset */
724 	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
725 
726 	if (obj->funcs && obj->funcs->mmap) {
727 		vma->vm_ops = obj->funcs->vm_ops;
728 
729 		drm_gem_object_get(obj);
730 		ret = obj->funcs->mmap(obj, vma);
731 		if (ret) {
732 			drm_gem_object_put(obj);
733 			return ret;
734 		}
735 		vma->vm_private_data = obj;
736 		return 0;
737 	}
738 
739 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
740 	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
741 	if (!priv || !fil) {
742 		ret = -ENOMEM;
743 		goto out;
744 	}
745 
746 	/* Used by drm_gem_mmap() to lookup the GEM object */
747 	priv->minor = obj->dev->primary;
748 	fil->private_data = priv;
749 
750 	ret = drm_vma_node_allow(&obj->vma_node, priv);
751 	if (ret)
752 		goto out;
753 
754 	ret = obj->dev->driver->fops->mmap(fil, vma);
755 
756 	drm_vma_node_revoke(&obj->vma_node, priv);
757 out:
758 	kfree(priv);
759 	kfree(fil);
760 
761 	return ret;
762 }
763 EXPORT_SYMBOL(drm_gem_prime_mmap);
764 
765 /**
766  * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
767  * @dma_buf: buffer to be mapped
768  * @vma: virtual address range
769  *
770  * Provides memory mapping for the buffer. This can be used as the
771  * &dma_buf_ops.mmap callback. It just forwards to &drm_driver.gem_prime_mmap,
772  * which should be set to drm_gem_prime_mmap().
773  *
774  * FIXME: There's really no point to this wrapper, drivers which need anything
775  * else but drm_gem_prime_mmap can roll their own &dma_buf_ops.mmap callback.
776  *
777  * Returns 0 on success or a negative error code on failure.
778  */
drm_gem_dmabuf_mmap(struct dma_buf * dma_buf,struct vm_area_struct * vma)779 int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
780 {
781 	struct drm_gem_object *obj = dma_buf->priv;
782 	struct drm_device *dev = obj->dev;
783 
784 	if (!dev->driver->gem_prime_mmap)
785 		return -ENOSYS;
786 
787 	return dev->driver->gem_prime_mmap(obj, vma);
788 }
789 EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
790 
791 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
792 	.cache_sgt_mapping = true,
793 	.attach = drm_gem_map_attach,
794 	.detach = drm_gem_map_detach,
795 	.map_dma_buf = drm_gem_map_dma_buf,
796 	.unmap_dma_buf = drm_gem_unmap_dma_buf,
797 	.release = drm_gem_dmabuf_release,
798 	.mmap = drm_gem_dmabuf_mmap,
799 	.vmap = drm_gem_dmabuf_vmap,
800 	.vunmap = drm_gem_dmabuf_vunmap,
801 };
802 
803 /**
804  * drm_prime_pages_to_sg - converts a page array into an sg list
805  * @dev: DRM device
806  * @pages: pointer to the array of page pointers to convert
807  * @nr_pages: length of the page vector
808  *
809  * This helper creates an sg table object from a set of pages
810  * the driver is responsible for mapping the pages into the
811  * importers address space for use with dma_buf itself.
812  *
813  * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
814  */
drm_prime_pages_to_sg(struct drm_device * dev,struct page ** pages,unsigned int nr_pages)815 struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
816 				       struct page **pages, unsigned int nr_pages)
817 {
818 	struct sg_table *sg;
819 	size_t max_segment = 0;
820 	int err;
821 
822 	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
823 	if (!sg)
824 		return ERR_PTR(-ENOMEM);
825 
826 	if (dev)
827 		max_segment = dma_max_mapping_size(dev->dev);
828 	if (max_segment == 0)
829 		max_segment = UINT_MAX;
830 	err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0,
831 						nr_pages << PAGE_SHIFT,
832 						max_segment, GFP_KERNEL);
833 	if (err) {
834 		kfree(sg);
835 		sg = ERR_PTR(err);
836 	}
837 	return sg;
838 }
839 EXPORT_SYMBOL(drm_prime_pages_to_sg);
840 
841 /**
842  * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
843  * @sgt: sg_table describing the buffer to check
844  *
845  * This helper calculates the contiguous size in the DMA address space
846  * of the the buffer described by the provided sg_table.
847  *
848  * This is useful for implementing
849  * &drm_gem_object_funcs.gem_prime_import_sg_table.
850  */
drm_prime_get_contiguous_size(struct sg_table * sgt)851 unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
852 {
853 	dma_addr_t expected = sg_dma_address(sgt->sgl);
854 	struct scatterlist *sg;
855 	unsigned long size = 0;
856 	int i;
857 
858 	for_each_sgtable_dma_sg(sgt, sg, i) {
859 		unsigned int len = sg_dma_len(sg);
860 
861 		if (!len)
862 			break;
863 		if (sg_dma_address(sg) != expected)
864 			break;
865 		expected += len;
866 		size += len;
867 	}
868 	return size;
869 }
870 EXPORT_SYMBOL(drm_prime_get_contiguous_size);
871 
872 /**
873  * drm_gem_prime_export - helper library implementation of the export callback
874  * @obj: GEM object to export
875  * @flags: flags like DRM_CLOEXEC and DRM_RDWR
876  *
877  * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
878  * using the PRIME helpers. It is used as the default in
879  * drm_gem_prime_handle_to_fd().
880  */
drm_gem_prime_export(struct drm_gem_object * obj,int flags)881 struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
882 				     int flags)
883 {
884 	struct drm_device *dev = obj->dev;
885 	struct dma_buf_export_info exp_info = {
886 		.exp_name = KBUILD_MODNAME, /* white lie for debug */
887 		.owner = dev->driver->fops->owner,
888 		.ops = &drm_gem_prime_dmabuf_ops,
889 		.size = obj->size,
890 		.flags = flags,
891 		.priv = obj,
892 		.resv = obj->resv,
893 	};
894 
895 	return drm_gem_dmabuf_export(dev, &exp_info);
896 }
897 EXPORT_SYMBOL(drm_gem_prime_export);
898 
899 /**
900  * drm_gem_prime_import_dev - core implementation of the import callback
901  * @dev: drm_device to import into
902  * @dma_buf: dma-buf object to import
903  * @attach_dev: struct device to dma_buf attach
904  *
905  * This is the core of drm_gem_prime_import(). It's designed to be called by
906  * drivers who want to use a different device structure than &drm_device.dev for
907  * attaching via dma_buf. This function calls
908  * &drm_driver.gem_prime_import_sg_table internally.
909  *
910  * Drivers must arrange to call drm_prime_gem_destroy() from their
911  * &drm_gem_object_funcs.free hook when using this function.
912  */
drm_gem_prime_import_dev(struct drm_device * dev,struct dma_buf * dma_buf,struct device * attach_dev)913 struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
914 					    struct dma_buf *dma_buf,
915 					    struct device *attach_dev)
916 {
917 	struct dma_buf_attachment *attach;
918 	struct sg_table *sgt;
919 	struct drm_gem_object *obj;
920 	int ret;
921 
922 	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
923 		obj = dma_buf->priv;
924 		if (obj->dev == dev) {
925 			/*
926 			 * Importing dmabuf exported from out own gem increases
927 			 * refcount on gem itself instead of f_count of dmabuf.
928 			 */
929 			drm_gem_object_get(obj);
930 			return obj;
931 		}
932 	}
933 
934 	if (!dev->driver->gem_prime_import_sg_table)
935 		return ERR_PTR(-EINVAL);
936 
937 	attach = dma_buf_attach(dma_buf, attach_dev);
938 	if (IS_ERR(attach))
939 		return ERR_CAST(attach);
940 
941 	get_dma_buf(dma_buf);
942 
943 	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
944 	if (IS_ERR(sgt)) {
945 		ret = PTR_ERR(sgt);
946 		goto fail_detach;
947 	}
948 
949 	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
950 	if (IS_ERR(obj)) {
951 		ret = PTR_ERR(obj);
952 		goto fail_unmap;
953 	}
954 
955 	obj->import_attach = attach;
956 	obj->resv = dma_buf->resv;
957 
958 	return obj;
959 
960 fail_unmap:
961 	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
962 fail_detach:
963 	dma_buf_detach(dma_buf, attach);
964 	dma_buf_put(dma_buf);
965 
966 	return ERR_PTR(ret);
967 }
968 EXPORT_SYMBOL(drm_gem_prime_import_dev);
969 
970 /**
971  * drm_gem_prime_import - helper library implementation of the import callback
972  * @dev: drm_device to import into
973  * @dma_buf: dma-buf object to import
974  *
975  * This is the implementation of the gem_prime_import functions for GEM drivers
976  * using the PRIME helpers. Drivers can use this as their
977  * &drm_driver.gem_prime_import implementation. It is used as the default
978  * implementation in drm_gem_prime_fd_to_handle().
979  *
980  * Drivers must arrange to call drm_prime_gem_destroy() from their
981  * &drm_gem_object_funcs.free hook when using this function.
982  */
drm_gem_prime_import(struct drm_device * dev,struct dma_buf * dma_buf)983 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
984 					    struct dma_buf *dma_buf)
985 {
986 	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
987 }
988 EXPORT_SYMBOL(drm_gem_prime_import);
989 
990 /**
991  * drm_prime_sg_to_page_array - convert an sg table into a page array
992  * @sgt: scatter-gather table to convert
993  * @pages: array of page pointers to store the pages in
994  * @max_entries: size of the passed-in array
995  *
996  * Exports an sg table into an array of pages.
997  *
998  * This function is deprecated and strongly discouraged to be used.
999  * The page array is only useful for page faults and those can corrupt fields
1000  * in the struct page if they are not handled by the exporting driver.
1001  */
drm_prime_sg_to_page_array(struct sg_table * sgt,struct page ** pages,int max_entries)1002 int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
1003 					    struct page **pages,
1004 					    int max_entries)
1005 {
1006 	struct sg_page_iter page_iter;
1007 	struct page **p = pages;
1008 
1009 	for_each_sgtable_page(sgt, &page_iter, 0) {
1010 		if (WARN_ON(p - pages >= max_entries))
1011 			return -1;
1012 		*p++ = sg_page_iter_page(&page_iter);
1013 	}
1014 	return 0;
1015 }
1016 EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1017 
1018 /**
1019  * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1020  * @sgt: scatter-gather table to convert
1021  * @addrs: array to store the dma bus address of each page
1022  * @max_entries: size of both the passed-in arrays
1023  *
1024  * Exports an sg table into an array of addresses.
1025  *
1026  * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1027  * implementation.
1028  */
drm_prime_sg_to_dma_addr_array(struct sg_table * sgt,dma_addr_t * addrs,int max_entries)1029 int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1030 				   int max_entries)
1031 {
1032 	struct sg_dma_page_iter dma_iter;
1033 	dma_addr_t *a = addrs;
1034 
1035 	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1036 		if (WARN_ON(a - addrs >= max_entries))
1037 			return -1;
1038 		*a++ = sg_page_iter_dma_address(&dma_iter);
1039 	}
1040 	return 0;
1041 }
1042 EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1043 
1044 /**
1045  * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1046  * @obj: GEM object which was created from a dma-buf
1047  * @sg: the sg-table which was pinned at import time
1048  *
1049  * This is the cleanup functions which GEM drivers need to call when they use
1050  * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1051  */
drm_prime_gem_destroy(struct drm_gem_object * obj,struct sg_table * sg)1052 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1053 {
1054 	struct dma_buf_attachment *attach;
1055 	struct dma_buf *dma_buf;
1056 
1057 	attach = obj->import_attach;
1058 	if (sg)
1059 		dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
1060 	dma_buf = attach->dmabuf;
1061 	dma_buf_detach(attach->dmabuf, attach);
1062 	/* remove the reference */
1063 	dma_buf_put(dma_buf);
1064 }
1065 EXPORT_SYMBOL(drm_prime_gem_destroy);
1066