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_locked(struct drm_prime_file_private * prime_fpriv,struct dma_buf * dma_buf)193 void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv,
194 					struct dma_buf *dma_buf)
195 {
196 	struct rb_node *rb;
197 
198 	rb = prime_fpriv->dmabufs.rb_node;
199 	while (rb) {
200 		struct drm_prime_member *member;
201 
202 		member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
203 		if (member->dma_buf == dma_buf) {
204 			rb_erase(&member->handle_rb, &prime_fpriv->handles);
205 			rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);
206 
207 			dma_buf_put(dma_buf);
208 			kfree(member);
209 			return;
210 		} else if (member->dma_buf < dma_buf) {
211 			rb = rb->rb_right;
212 		} else {
213 			rb = rb->rb_left;
214 		}
215 	}
216 }
217 
drm_prime_init_file_private(struct drm_prime_file_private * prime_fpriv)218 void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
219 {
220 	mutex_init(&prime_fpriv->lock);
221 	prime_fpriv->dmabufs = RB_ROOT;
222 	prime_fpriv->handles = RB_ROOT;
223 }
224 
drm_prime_destroy_file_private(struct drm_prime_file_private * prime_fpriv)225 void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
226 {
227 	/* by now drm_gem_release should've made sure the list is empty */
228 	WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
229 }
230 
231 /**
232  * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
233  * @dev: parent device for the exported dmabuf
234  * @exp_info: the export information used by dma_buf_export()
235  *
236  * This wraps dma_buf_export() for use by generic GEM drivers that are using
237  * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
238  * a reference to the &drm_device and the exported &drm_gem_object (stored in
239  * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
240  *
241  * Returns the new dmabuf.
242  */
drm_gem_dmabuf_export(struct drm_device * dev,struct dma_buf_export_info * exp_info)243 struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
244 				      struct dma_buf_export_info *exp_info)
245 {
246 	struct drm_gem_object *obj = exp_info->priv;
247 	struct dma_buf *dma_buf;
248 
249 	dma_buf = dma_buf_export(exp_info);
250 	if (IS_ERR(dma_buf))
251 		return dma_buf;
252 
253 	drm_dev_get(dev);
254 	drm_gem_object_get(obj);
255 	dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
256 
257 	return dma_buf;
258 }
259 EXPORT_SYMBOL(drm_gem_dmabuf_export);
260 
261 /**
262  * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
263  * @dma_buf: buffer to be released
264  *
265  * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
266  * must use this in their &dma_buf_ops structure as the release callback.
267  * drm_gem_dmabuf_release() should be used in conjunction with
268  * drm_gem_dmabuf_export().
269  */
drm_gem_dmabuf_release(struct dma_buf * dma_buf)270 void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
271 {
272 	struct drm_gem_object *obj = dma_buf->priv;
273 	struct drm_device *dev = obj->dev;
274 
275 	/* drop the reference on the export fd holds */
276 	drm_gem_object_put(obj);
277 
278 	drm_dev_put(dev);
279 }
280 EXPORT_SYMBOL(drm_gem_dmabuf_release);
281 
282 /**
283  * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
284  * @dev: dev to export the buffer from
285  * @file_priv: drm file-private structure
286  * @prime_fd: fd id of the dma-buf which should be imported
287  * @handle: pointer to storage for the handle of the imported buffer object
288  *
289  * This is the PRIME import function which must be used mandatorily by GEM
290  * drivers to ensure correct lifetime management of the underlying GEM object.
291  * The actual importing of GEM object from the dma-buf is done through the
292  * &drm_driver.gem_prime_import driver callback.
293  *
294  * Returns 0 on success or a negative error code on failure.
295  */
drm_gem_prime_fd_to_handle(struct drm_device * dev,struct drm_file * file_priv,int prime_fd,uint32_t * handle)296 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
297 			       struct drm_file *file_priv, int prime_fd,
298 			       uint32_t *handle)
299 {
300 	struct dma_buf *dma_buf;
301 	struct drm_gem_object *obj;
302 	int ret;
303 
304 	dma_buf = dma_buf_get(prime_fd);
305 	if (IS_ERR(dma_buf))
306 		return PTR_ERR(dma_buf);
307 
308 	mutex_lock(&file_priv->prime.lock);
309 
310 	ret = drm_prime_lookup_buf_handle(&file_priv->prime,
311 			dma_buf, handle);
312 	if (ret == 0)
313 		goto out_put;
314 
315 	/* never seen this one, need to import */
316 	mutex_lock(&dev->object_name_lock);
317 	if (dev->driver->gem_prime_import)
318 		obj = dev->driver->gem_prime_import(dev, dma_buf);
319 	else
320 		obj = drm_gem_prime_import(dev, dma_buf);
321 	if (IS_ERR(obj)) {
322 		ret = PTR_ERR(obj);
323 		goto out_unlock;
324 	}
325 
326 	if (obj->dma_buf) {
327 		WARN_ON(obj->dma_buf != dma_buf);
328 	} else {
329 		obj->dma_buf = dma_buf;
330 		get_dma_buf(dma_buf);
331 	}
332 
333 	/* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
334 	ret = drm_gem_handle_create_tail(file_priv, obj, handle);
335 	drm_gem_object_put(obj);
336 	if (ret)
337 		goto out_put;
338 
339 	ret = drm_prime_add_buf_handle(&file_priv->prime,
340 			dma_buf, *handle);
341 	mutex_unlock(&file_priv->prime.lock);
342 	if (ret)
343 		goto fail;
344 
345 	dma_buf_put(dma_buf);
346 
347 	return 0;
348 
349 fail:
350 	/* hmm, if driver attached, we are relying on the free-object path
351 	 * to detach.. which seems ok..
352 	 */
353 	drm_gem_handle_delete(file_priv, *handle);
354 	dma_buf_put(dma_buf);
355 	return ret;
356 
357 out_unlock:
358 	mutex_unlock(&dev->object_name_lock);
359 out_put:
360 	mutex_unlock(&file_priv->prime.lock);
361 	dma_buf_put(dma_buf);
362 	return ret;
363 }
364 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
365 
drm_prime_fd_to_handle_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)366 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
367 				 struct drm_file *file_priv)
368 {
369 	struct drm_prime_handle *args = data;
370 
371 	if (!dev->driver->prime_fd_to_handle)
372 		return -ENOSYS;
373 
374 	return dev->driver->prime_fd_to_handle(dev, file_priv,
375 			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_fd - 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  * @prime_fd: pointer to storage for the fd id of the create dma-buf
419  *
420  * This is the PRIME export function which must be used mandatorily by GEM
421  * drivers to ensure correct lifetime management of the underlying GEM object.
422  * The actual exporting from GEM object to a dma-buf is done through the
423  * &drm_gem_object_funcs.export callback.
424  */
drm_gem_prime_handle_to_fd(struct drm_device * dev,struct drm_file * file_priv,uint32_t handle,uint32_t flags,int * prime_fd)425 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
426 			       struct drm_file *file_priv, uint32_t handle,
427 			       uint32_t flags,
428 			       int *prime_fd)
429 {
430 	struct drm_gem_object *obj;
431 	int ret = 0;
432 	struct dma_buf *dmabuf;
433 
434 	mutex_lock(&file_priv->prime.lock);
435 	obj = drm_gem_object_lookup(file_priv, handle);
436 	if (!obj)  {
437 		ret = -ENOENT;
438 		goto out_unlock;
439 	}
440 
441 	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
442 	if (dmabuf) {
443 		get_dma_buf(dmabuf);
444 		goto out_have_handle;
445 	}
446 
447 	mutex_lock(&dev->object_name_lock);
448 	/* re-export the original imported object */
449 	if (obj->import_attach) {
450 		dmabuf = obj->import_attach->dmabuf;
451 		get_dma_buf(dmabuf);
452 		goto out_have_obj;
453 	}
454 
455 	if (obj->dma_buf) {
456 		get_dma_buf(obj->dma_buf);
457 		dmabuf = obj->dma_buf;
458 		goto out_have_obj;
459 	}
460 
461 	dmabuf = export_and_register_object(dev, obj, flags);
462 	if (IS_ERR(dmabuf)) {
463 		/* normally the created dma-buf takes ownership of the ref,
464 		 * but if that fails then drop the ref
465 		 */
466 		ret = PTR_ERR(dmabuf);
467 		mutex_unlock(&dev->object_name_lock);
468 		goto out;
469 	}
470 
471 out_have_obj:
472 	/*
473 	 * If we've exported this buffer then cheat and add it to the import list
474 	 * so we get the correct handle back. We must do this under the
475 	 * protection of dev->object_name_lock to ensure that a racing gem close
476 	 * ioctl doesn't miss to remove this buffer handle from the cache.
477 	 */
478 	ret = drm_prime_add_buf_handle(&file_priv->prime,
479 				       dmabuf, handle);
480 	mutex_unlock(&dev->object_name_lock);
481 	if (ret)
482 		goto fail_put_dmabuf;
483 
484 out_have_handle:
485 	ret = dma_buf_fd(dmabuf, flags);
486 	/*
487 	 * We must _not_ remove the buffer from the handle cache since the newly
488 	 * created dma buf is already linked in the global obj->dma_buf pointer,
489 	 * and that is invariant as long as a userspace gem handle exists.
490 	 * Closing the handle will clean out the cache anyway, so we don't leak.
491 	 */
492 	if (ret < 0) {
493 		goto fail_put_dmabuf;
494 	} else {
495 		*prime_fd = ret;
496 		ret = 0;
497 	}
498 
499 	goto out;
500 
501 fail_put_dmabuf:
502 	dma_buf_put(dmabuf);
503 out:
504 	drm_gem_object_put(obj);
505 out_unlock:
506 	mutex_unlock(&file_priv->prime.lock);
507 
508 	return ret;
509 }
510 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
511 
drm_prime_handle_to_fd_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)512 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
513 				 struct drm_file *file_priv)
514 {
515 	struct drm_prime_handle *args = data;
516 
517 	if (!dev->driver->prime_handle_to_fd)
518 		return -ENOSYS;
519 
520 	/* check flags are valid */
521 	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
522 		return -EINVAL;
523 
524 	return dev->driver->prime_handle_to_fd(dev, file_priv,
525 			args->handle, args->flags, &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.
544  *
545  * For kernel-internal access there's drm_gem_dmabuf_vmap() and
546  * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
547  * drm_gem_dmabuf_mmap().
548  *
549  * Note that these export helpers can only be used if the underlying backing
550  * storage is fully coherent and either permanently pinned, or it is safe to pin
551  * it indefinitely.
552  *
553  * FIXME: The underlying helper functions are named rather inconsistently.
554  *
555  * Importing buffers
556  * ~~~~~~~~~~~~~~~~~
557  *
558  * Importing dma-bufs using drm_gem_prime_import() relies on
559  * &drm_driver.gem_prime_import_sg_table.
560  *
561  * Note that similarly to the export helpers this permanently pins the
562  * underlying backing storage. Which is ok for scanout, but is not the best
563  * option for sharing lots of buffers for rendering.
564  */
565 
566 /**
567  * drm_gem_map_attach - dma_buf attach implementation for GEM
568  * @dma_buf: buffer to attach device to
569  * @attach: buffer attachment data
570  *
571  * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
572  * used as the &dma_buf_ops.attach callback. Must be used together with
573  * drm_gem_map_detach().
574  *
575  * Returns 0 on success, negative error code on failure.
576  */
drm_gem_map_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)577 int drm_gem_map_attach(struct dma_buf *dma_buf,
578 		       struct dma_buf_attachment *attach)
579 {
580 	struct drm_gem_object *obj = dma_buf->priv;
581 
582 	return drm_gem_pin(obj);
583 }
584 EXPORT_SYMBOL(drm_gem_map_attach);
585 
586 /**
587  * drm_gem_map_detach - dma_buf detach implementation for GEM
588  * @dma_buf: buffer to detach from
589  * @attach: attachment to be detached
590  *
591  * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
592  * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
593  * &dma_buf_ops.detach callback.
594  */
drm_gem_map_detach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)595 void drm_gem_map_detach(struct dma_buf *dma_buf,
596 			struct dma_buf_attachment *attach)
597 {
598 	struct drm_gem_object *obj = dma_buf->priv;
599 
600 	drm_gem_unpin(obj);
601 }
602 EXPORT_SYMBOL(drm_gem_map_detach);
603 
604 /**
605  * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
606  * @attach: attachment whose scatterlist is to be returned
607  * @dir: direction of DMA transfer
608  *
609  * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
610  * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
611  * with drm_gem_unmap_dma_buf().
612  *
613  * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
614  * on error. May return -EINTR if it is interrupted by a signal.
615  */
drm_gem_map_dma_buf(struct dma_buf_attachment * attach,enum dma_data_direction dir)616 struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
617 				     enum dma_data_direction dir)
618 {
619 	struct drm_gem_object *obj = attach->dmabuf->priv;
620 	struct sg_table *sgt;
621 	int ret;
622 
623 	if (WARN_ON(dir == DMA_NONE))
624 		return ERR_PTR(-EINVAL);
625 
626 	if (WARN_ON(!obj->funcs->get_sg_table))
627 		return ERR_PTR(-ENOSYS);
628 
629 	sgt = obj->funcs->get_sg_table(obj);
630 	if (IS_ERR(sgt))
631 		return sgt;
632 
633 	ret = dma_map_sgtable(attach->dev, sgt, dir,
634 			      DMA_ATTR_SKIP_CPU_SYNC);
635 	if (ret) {
636 		sg_free_table(sgt);
637 		kfree(sgt);
638 		sgt = ERR_PTR(ret);
639 	}
640 
641 	return sgt;
642 }
643 EXPORT_SYMBOL(drm_gem_map_dma_buf);
644 
645 /**
646  * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
647  * @attach: attachment to unmap buffer from
648  * @sgt: scatterlist info of the buffer to unmap
649  * @dir: direction of DMA transfer
650  *
651  * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
652  */
drm_gem_unmap_dma_buf(struct dma_buf_attachment * attach,struct sg_table * sgt,enum dma_data_direction dir)653 void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
654 			   struct sg_table *sgt,
655 			   enum dma_data_direction dir)
656 {
657 	if (!sgt)
658 		return;
659 
660 	dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
661 	sg_free_table(sgt);
662 	kfree(sgt);
663 }
664 EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
665 
666 /**
667  * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
668  * @dma_buf: buffer to be mapped
669  * @map: the virtual address of the buffer
670  *
671  * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
672  * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
673  * The kernel virtual address is returned in map.
674  *
675  * Returns 0 on success or a negative errno code otherwise.
676  */
drm_gem_dmabuf_vmap(struct dma_buf * dma_buf,struct dma_buf_map * map)677 int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
678 {
679 	struct drm_gem_object *obj = dma_buf->priv;
680 
681 	return drm_gem_vmap(obj, map);
682 }
683 EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
684 
685 /**
686  * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
687  * @dma_buf: buffer to be unmapped
688  * @map: the virtual address of the buffer
689  *
690  * Releases a kernel virtual mapping. This can be used as the
691  * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
692  */
drm_gem_dmabuf_vunmap(struct dma_buf * dma_buf,struct dma_buf_map * map)693 void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
694 {
695 	struct drm_gem_object *obj = dma_buf->priv;
696 
697 	drm_gem_vunmap(obj, map);
698 }
699 EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
700 
701 /**
702  * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
703  * @obj: GEM object
704  * @vma: Virtual address range
705  *
706  * This function sets up a userspace mapping for PRIME exported buffers using
707  * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
708  * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
709  * called to set up the mapping.
710  *
711  * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
712  */
drm_gem_prime_mmap(struct drm_gem_object * obj,struct vm_area_struct * vma)713 int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
714 {
715 	struct drm_file *priv;
716 	struct file *fil;
717 	int ret;
718 
719 	/* Add the fake offset */
720 	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
721 
722 	if (obj->funcs && obj->funcs->mmap) {
723 		vma->vm_ops = obj->funcs->vm_ops;
724 
725 		drm_gem_object_get(obj);
726 		ret = obj->funcs->mmap(obj, vma);
727 		if (ret) {
728 			drm_gem_object_put(obj);
729 			return ret;
730 		}
731 		vma->vm_private_data = obj;
732 		return 0;
733 	}
734 
735 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
736 	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
737 	if (!priv || !fil) {
738 		ret = -ENOMEM;
739 		goto out;
740 	}
741 
742 	/* Used by drm_gem_mmap() to lookup the GEM object */
743 	priv->minor = obj->dev->primary;
744 	fil->private_data = priv;
745 
746 	ret = drm_vma_node_allow(&obj->vma_node, priv);
747 	if (ret)
748 		goto out;
749 
750 	ret = obj->dev->driver->fops->mmap(fil, vma);
751 
752 	drm_vma_node_revoke(&obj->vma_node, priv);
753 out:
754 	kfree(priv);
755 	kfree(fil);
756 
757 	return ret;
758 }
759 EXPORT_SYMBOL(drm_gem_prime_mmap);
760 
761 /**
762  * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
763  * @dma_buf: buffer to be mapped
764  * @vma: virtual address range
765  *
766  * Provides memory mapping for the buffer. This can be used as the
767  * &dma_buf_ops.mmap callback. It just forwards to &drm_driver.gem_prime_mmap,
768  * which should be set to drm_gem_prime_mmap().
769  *
770  * FIXME: There's really no point to this wrapper, drivers which need anything
771  * else but drm_gem_prime_mmap can roll their own &dma_buf_ops.mmap callback.
772  *
773  * Returns 0 on success or a negative error code on failure.
774  */
drm_gem_dmabuf_mmap(struct dma_buf * dma_buf,struct vm_area_struct * vma)775 int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
776 {
777 	struct drm_gem_object *obj = dma_buf->priv;
778 	struct drm_device *dev = obj->dev;
779 
780 	if (!dev->driver->gem_prime_mmap)
781 		return -ENOSYS;
782 
783 	return dev->driver->gem_prime_mmap(obj, vma);
784 }
785 EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
786 
787 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
788 	.cache_sgt_mapping = true,
789 	.attach = drm_gem_map_attach,
790 	.detach = drm_gem_map_detach,
791 	.map_dma_buf = drm_gem_map_dma_buf,
792 	.unmap_dma_buf = drm_gem_unmap_dma_buf,
793 	.release = drm_gem_dmabuf_release,
794 	.mmap = drm_gem_dmabuf_mmap,
795 	.vmap = drm_gem_dmabuf_vmap,
796 	.vunmap = drm_gem_dmabuf_vunmap,
797 };
798 
799 /**
800  * drm_prime_pages_to_sg - converts a page array into an sg list
801  * @dev: DRM device
802  * @pages: pointer to the array of page pointers to convert
803  * @nr_pages: length of the page vector
804  *
805  * This helper creates an sg table object from a set of pages
806  * the driver is responsible for mapping the pages into the
807  * importers address space for use with dma_buf itself.
808  *
809  * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
810  */
drm_prime_pages_to_sg(struct drm_device * dev,struct page ** pages,unsigned int nr_pages)811 struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
812 				       struct page **pages, unsigned int nr_pages)
813 {
814 	struct sg_table *sg;
815 	size_t max_segment = 0;
816 	int err;
817 
818 	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
819 	if (!sg)
820 		return ERR_PTR(-ENOMEM);
821 
822 	if (dev)
823 		max_segment = dma_max_mapping_size(dev->dev);
824 	if (max_segment == 0)
825 		max_segment = UINT_MAX;
826 	err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0,
827 						nr_pages << PAGE_SHIFT,
828 						max_segment, GFP_KERNEL);
829 	if (err) {
830 		kfree(sg);
831 		sg = ERR_PTR(err);
832 	}
833 	return sg;
834 }
835 EXPORT_SYMBOL(drm_prime_pages_to_sg);
836 
837 /**
838  * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
839  * @sgt: sg_table describing the buffer to check
840  *
841  * This helper calculates the contiguous size in the DMA address space
842  * of the the buffer described by the provided sg_table.
843  *
844  * This is useful for implementing
845  * &drm_gem_object_funcs.gem_prime_import_sg_table.
846  */
drm_prime_get_contiguous_size(struct sg_table * sgt)847 unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
848 {
849 	dma_addr_t expected = sg_dma_address(sgt->sgl);
850 	struct scatterlist *sg;
851 	unsigned long size = 0;
852 	int i;
853 
854 	for_each_sgtable_dma_sg(sgt, sg, i) {
855 		unsigned int len = sg_dma_len(sg);
856 
857 		if (!len)
858 			break;
859 		if (sg_dma_address(sg) != expected)
860 			break;
861 		expected += len;
862 		size += len;
863 	}
864 	return size;
865 }
866 EXPORT_SYMBOL(drm_prime_get_contiguous_size);
867 
868 /**
869  * drm_gem_prime_export - helper library implementation of the export callback
870  * @obj: GEM object to export
871  * @flags: flags like DRM_CLOEXEC and DRM_RDWR
872  *
873  * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
874  * using the PRIME helpers. It is used as the default in
875  * drm_gem_prime_handle_to_fd().
876  */
drm_gem_prime_export(struct drm_gem_object * obj,int flags)877 struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
878 				     int flags)
879 {
880 	struct drm_device *dev = obj->dev;
881 	struct dma_buf_export_info exp_info = {
882 		.exp_name = KBUILD_MODNAME, /* white lie for debug */
883 		.owner = dev->driver->fops->owner,
884 		.ops = &drm_gem_prime_dmabuf_ops,
885 		.size = obj->size,
886 		.flags = flags,
887 		.priv = obj,
888 		.resv = obj->resv,
889 	};
890 
891 	return drm_gem_dmabuf_export(dev, &exp_info);
892 }
893 EXPORT_SYMBOL(drm_gem_prime_export);
894 
895 /**
896  * drm_gem_prime_import_dev - core implementation of the import callback
897  * @dev: drm_device to import into
898  * @dma_buf: dma-buf object to import
899  * @attach_dev: struct device to dma_buf attach
900  *
901  * This is the core of drm_gem_prime_import(). It's designed to be called by
902  * drivers who want to use a different device structure than &drm_device.dev for
903  * attaching via dma_buf. This function calls
904  * &drm_driver.gem_prime_import_sg_table internally.
905  *
906  * Drivers must arrange to call drm_prime_gem_destroy() from their
907  * &drm_gem_object_funcs.free hook when using this function.
908  */
drm_gem_prime_import_dev(struct drm_device * dev,struct dma_buf * dma_buf,struct device * attach_dev)909 struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
910 					    struct dma_buf *dma_buf,
911 					    struct device *attach_dev)
912 {
913 	struct dma_buf_attachment *attach;
914 	struct sg_table *sgt;
915 	struct drm_gem_object *obj;
916 	int ret;
917 
918 	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
919 		obj = dma_buf->priv;
920 		if (obj->dev == dev) {
921 			/*
922 			 * Importing dmabuf exported from out own gem increases
923 			 * refcount on gem itself instead of f_count of dmabuf.
924 			 */
925 			drm_gem_object_get(obj);
926 			return obj;
927 		}
928 	}
929 
930 	if (!dev->driver->gem_prime_import_sg_table)
931 		return ERR_PTR(-EINVAL);
932 
933 	attach = dma_buf_attach(dma_buf, attach_dev);
934 	if (IS_ERR(attach))
935 		return ERR_CAST(attach);
936 
937 	get_dma_buf(dma_buf);
938 
939 	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
940 	if (IS_ERR(sgt)) {
941 		ret = PTR_ERR(sgt);
942 		goto fail_detach;
943 	}
944 
945 	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
946 	if (IS_ERR(obj)) {
947 		ret = PTR_ERR(obj);
948 		goto fail_unmap;
949 	}
950 
951 	obj->import_attach = attach;
952 	obj->resv = dma_buf->resv;
953 
954 	return obj;
955 
956 fail_unmap:
957 	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
958 fail_detach:
959 	dma_buf_detach(dma_buf, attach);
960 	dma_buf_put(dma_buf);
961 
962 	return ERR_PTR(ret);
963 }
964 EXPORT_SYMBOL(drm_gem_prime_import_dev);
965 
966 /**
967  * drm_gem_prime_import - helper library implementation of the import callback
968  * @dev: drm_device to import into
969  * @dma_buf: dma-buf object to import
970  *
971  * This is the implementation of the gem_prime_import functions for GEM drivers
972  * using the PRIME helpers. Drivers can use this as their
973  * &drm_driver.gem_prime_import implementation. It is used as the default
974  * implementation in drm_gem_prime_fd_to_handle().
975  *
976  * Drivers must arrange to call drm_prime_gem_destroy() from their
977  * &drm_gem_object_funcs.free hook when using this function.
978  */
drm_gem_prime_import(struct drm_device * dev,struct dma_buf * dma_buf)979 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
980 					    struct dma_buf *dma_buf)
981 {
982 	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
983 }
984 EXPORT_SYMBOL(drm_gem_prime_import);
985 
986 /**
987  * drm_prime_sg_to_page_array - convert an sg table into a page array
988  * @sgt: scatter-gather table to convert
989  * @pages: array of page pointers to store the pages in
990  * @max_entries: size of the passed-in array
991  *
992  * Exports an sg table into an array of pages.
993  *
994  * This function is deprecated and strongly discouraged to be used.
995  * The page array is only useful for page faults and those can corrupt fields
996  * in the struct page if they are not handled by the exporting driver.
997  */
drm_prime_sg_to_page_array(struct sg_table * sgt,struct page ** pages,int max_entries)998 int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
999 					    struct page **pages,
1000 					    int max_entries)
1001 {
1002 	struct sg_page_iter page_iter;
1003 	struct page **p = pages;
1004 
1005 	for_each_sgtable_page(sgt, &page_iter, 0) {
1006 		if (WARN_ON(p - pages >= max_entries))
1007 			return -1;
1008 		*p++ = sg_page_iter_page(&page_iter);
1009 	}
1010 	return 0;
1011 }
1012 EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1013 
1014 /**
1015  * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1016  * @sgt: scatter-gather table to convert
1017  * @addrs: array to store the dma bus address of each page
1018  * @max_entries: size of both the passed-in arrays
1019  *
1020  * Exports an sg table into an array of addresses.
1021  *
1022  * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1023  * implementation.
1024  */
drm_prime_sg_to_dma_addr_array(struct sg_table * sgt,dma_addr_t * addrs,int max_entries)1025 int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1026 				   int max_entries)
1027 {
1028 	struct sg_dma_page_iter dma_iter;
1029 	dma_addr_t *a = addrs;
1030 
1031 	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1032 		if (WARN_ON(a - addrs >= max_entries))
1033 			return -1;
1034 		*a++ = sg_page_iter_dma_address(&dma_iter);
1035 	}
1036 	return 0;
1037 }
1038 EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1039 
1040 /**
1041  * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1042  * @obj: GEM object which was created from a dma-buf
1043  * @sg: the sg-table which was pinned at import time
1044  *
1045  * This is the cleanup functions which GEM drivers need to call when they use
1046  * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1047  */
drm_prime_gem_destroy(struct drm_gem_object * obj,struct sg_table * sg)1048 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1049 {
1050 	struct dma_buf_attachment *attach;
1051 	struct dma_buf *dma_buf;
1052 
1053 	attach = obj->import_attach;
1054 	if (sg)
1055 		dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
1056 	dma_buf = attach->dmabuf;
1057 	dma_buf_detach(attach->dmabuf, attach);
1058 	/* remove the reference */
1059 	dma_buf_put(dma_buf);
1060 }
1061 EXPORT_SYMBOL(drm_prime_gem_destroy);
1062