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 static 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 
drm_prime_fd_to_handle_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)364 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
365 				 struct drm_file *file_priv)
366 {
367 	struct drm_prime_handle *args = data;
368 
369 	if (dev->driver->prime_fd_to_handle) {
370 		return dev->driver->prime_fd_to_handle(dev, file_priv, args->fd,
371 						       &args->handle);
372 	}
373 
374 	return drm_gem_prime_fd_to_handle(dev, file_priv, args->fd, &args->handle);
375 }
376 
export_and_register_object(struct drm_device * dev,struct drm_gem_object * obj,uint32_t flags)377 static struct dma_buf *export_and_register_object(struct drm_device *dev,
378 						  struct drm_gem_object *obj,
379 						  uint32_t flags)
380 {
381 	struct dma_buf *dmabuf;
382 
383 	/* prevent races with concurrent gem_close. */
384 	if (obj->handle_count == 0) {
385 		dmabuf = ERR_PTR(-ENOENT);
386 		return dmabuf;
387 	}
388 
389 	if (obj->funcs && obj->funcs->export)
390 		dmabuf = obj->funcs->export(obj, flags);
391 	else
392 		dmabuf = drm_gem_prime_export(obj, flags);
393 	if (IS_ERR(dmabuf)) {
394 		/* normally the created dma-buf takes ownership of the ref,
395 		 * but if that fails then drop the ref
396 		 */
397 		return dmabuf;
398 	}
399 
400 	/*
401 	 * Note that callers do not need to clean up the export cache
402 	 * since the check for obj->handle_count guarantees that someone
403 	 * will clean it up.
404 	 */
405 	obj->dma_buf = dmabuf;
406 	get_dma_buf(obj->dma_buf);
407 
408 	return dmabuf;
409 }
410 
411 /*
412  * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
413  * @dev: dev to export the buffer from
414  * @file_priv: drm file-private structure
415  * @handle: buffer handle to export
416  * @flags: flags like DRM_CLOEXEC
417  * @prime_fd: pointer to storage for the fd id of the create dma-buf
418  *
419  * This is the PRIME export function which must be used mandatorily by GEM
420  * drivers to ensure correct lifetime management of the underlying GEM object.
421  * The actual exporting from GEM object to a dma-buf is done through the
422  * &drm_gem_object_funcs.export callback.
423  */
drm_gem_prime_handle_to_fd(struct drm_device * dev,struct drm_file * file_priv,uint32_t handle,uint32_t flags,int * prime_fd)424 static int drm_gem_prime_handle_to_fd(struct drm_device *dev,
425 				      struct drm_file *file_priv, uint32_t handle,
426 				      uint32_t flags,
427 				      int *prime_fd)
428 {
429 	struct drm_gem_object *obj;
430 	int ret = 0;
431 	struct dma_buf *dmabuf;
432 
433 	mutex_lock(&file_priv->prime.lock);
434 	obj = drm_gem_object_lookup(file_priv, handle);
435 	if (!obj)  {
436 		ret = -ENOENT;
437 		goto out_unlock;
438 	}
439 
440 	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
441 	if (dmabuf) {
442 		get_dma_buf(dmabuf);
443 		goto out_have_handle;
444 	}
445 
446 	mutex_lock(&dev->object_name_lock);
447 	/* re-export the original imported object */
448 	if (obj->import_attach) {
449 		dmabuf = obj->import_attach->dmabuf;
450 		get_dma_buf(dmabuf);
451 		goto out_have_obj;
452 	}
453 
454 	if (obj->dma_buf) {
455 		get_dma_buf(obj->dma_buf);
456 		dmabuf = obj->dma_buf;
457 		goto out_have_obj;
458 	}
459 
460 	dmabuf = export_and_register_object(dev, obj, flags);
461 	if (IS_ERR(dmabuf)) {
462 		/* normally the created dma-buf takes ownership of the ref,
463 		 * but if that fails then drop the ref
464 		 */
465 		ret = PTR_ERR(dmabuf);
466 		mutex_unlock(&dev->object_name_lock);
467 		goto out;
468 	}
469 
470 out_have_obj:
471 	/*
472 	 * If we've exported this buffer then cheat and add it to the import list
473 	 * so we get the correct handle back. We must do this under the
474 	 * protection of dev->object_name_lock to ensure that a racing gem close
475 	 * ioctl doesn't miss to remove this buffer handle from the cache.
476 	 */
477 	ret = drm_prime_add_buf_handle(&file_priv->prime,
478 				       dmabuf, handle);
479 	mutex_unlock(&dev->object_name_lock);
480 	if (ret)
481 		goto fail_put_dmabuf;
482 
483 out_have_handle:
484 	ret = dma_buf_fd(dmabuf, flags);
485 	/*
486 	 * We must _not_ remove the buffer from the handle cache since the newly
487 	 * created dma buf is already linked in the global obj->dma_buf pointer,
488 	 * and that is invariant as long as a userspace gem handle exists.
489 	 * Closing the handle will clean out the cache anyway, so we don't leak.
490 	 */
491 	if (ret < 0) {
492 		goto fail_put_dmabuf;
493 	} else {
494 		*prime_fd = ret;
495 		ret = 0;
496 	}
497 
498 	goto out;
499 
500 fail_put_dmabuf:
501 	dma_buf_put(dmabuf);
502 out:
503 	drm_gem_object_put(obj);
504 out_unlock:
505 	mutex_unlock(&file_priv->prime.lock);
506 
507 	return ret;
508 }
509 
drm_prime_handle_to_fd_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)510 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
511 				 struct drm_file *file_priv)
512 {
513 	struct drm_prime_handle *args = data;
514 
515 	/* check flags are valid */
516 	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
517 		return -EINVAL;
518 
519 	if (dev->driver->prime_handle_to_fd) {
520 		return dev->driver->prime_handle_to_fd(dev, file_priv,
521 						       args->handle, args->flags,
522 						       &args->fd);
523 	}
524 	return drm_gem_prime_handle_to_fd(dev, file_priv, args->handle,
525 					  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. If &drm_gem_object_funcs.get_sg_table is
544  * unimplemented, exports into another device are rejected.
545  *
546  * For kernel-internal access there's drm_gem_dmabuf_vmap() and
547  * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
548  * drm_gem_dmabuf_mmap().
549  *
550  * Note that these export helpers can only be used if the underlying backing
551  * storage is fully coherent and either permanently pinned, or it is safe to pin
552  * it indefinitely.
553  *
554  * FIXME: The underlying helper functions are named rather inconsistently.
555  *
556  * Importing buffers
557  * ~~~~~~~~~~~~~~~~~
558  *
559  * Importing dma-bufs using drm_gem_prime_import() relies on
560  * &drm_driver.gem_prime_import_sg_table.
561  *
562  * Note that similarly to the export helpers this permanently pins the
563  * underlying backing storage. Which is ok for scanout, but is not the best
564  * option for sharing lots of buffers for rendering.
565  */
566 
567 /**
568  * drm_gem_map_attach - dma_buf attach implementation for GEM
569  * @dma_buf: buffer to attach device to
570  * @attach: buffer attachment data
571  *
572  * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
573  * used as the &dma_buf_ops.attach callback. Must be used together with
574  * drm_gem_map_detach().
575  *
576  * Returns 0 on success, negative error code on failure.
577  */
drm_gem_map_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)578 int drm_gem_map_attach(struct dma_buf *dma_buf,
579 		       struct dma_buf_attachment *attach)
580 {
581 	struct drm_gem_object *obj = dma_buf->priv;
582 
583 	if (!obj->funcs->get_sg_table)
584 		return -ENOSYS;
585 
586 	return drm_gem_pin(obj);
587 }
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  */
drm_gem_prime_mmap(struct drm_gem_object * obj,struct vm_area_struct * vma)715 int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
716 {
717 	struct drm_file *priv;
718 	struct file *fil;
719 	int ret;
720 
721 	/* Add the fake offset */
722 	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
723 
724 	if (obj->funcs && obj->funcs->mmap) {
725 		vma->vm_ops = obj->funcs->vm_ops;
726 
727 		drm_gem_object_get(obj);
728 		ret = obj->funcs->mmap(obj, vma);
729 		if (ret) {
730 			drm_gem_object_put(obj);
731 			return ret;
732 		}
733 		vma->vm_private_data = obj;
734 		return 0;
735 	}
736 
737 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
738 	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
739 	if (!priv || !fil) {
740 		ret = -ENOMEM;
741 		goto out;
742 	}
743 
744 	/* Used by drm_gem_mmap() to lookup the GEM object */
745 	priv->minor = obj->dev->primary;
746 	fil->private_data = priv;
747 
748 	ret = drm_vma_node_allow(&obj->vma_node, priv);
749 	if (ret)
750 		goto out;
751 
752 	ret = obj->dev->driver->fops->mmap(fil, vma);
753 
754 	drm_vma_node_revoke(&obj->vma_node, priv);
755 out:
756 	kfree(priv);
757 	kfree(fil);
758 
759 	return ret;
760 }
761 EXPORT_SYMBOL(drm_gem_prime_mmap);
762 
763 /**
764  * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
765  * @dma_buf: buffer to be mapped
766  * @vma: virtual address range
767  *
768  * Provides memory mapping for the buffer. This can be used as the
769  * &dma_buf_ops.mmap callback. It just forwards to drm_gem_prime_mmap().
770  *
771  * Returns 0 on success or a negative error code on failure.
772  */
drm_gem_dmabuf_mmap(struct dma_buf * dma_buf,struct vm_area_struct * vma)773 int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
774 {
775 	struct drm_gem_object *obj = dma_buf->priv;
776 
777 	return drm_gem_prime_mmap(obj, vma);
778 }
779 EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
780 
781 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
782 	.cache_sgt_mapping = true,
783 	.attach = drm_gem_map_attach,
784 	.detach = drm_gem_map_detach,
785 	.map_dma_buf = drm_gem_map_dma_buf,
786 	.unmap_dma_buf = drm_gem_unmap_dma_buf,
787 	.release = drm_gem_dmabuf_release,
788 	.mmap = drm_gem_dmabuf_mmap,
789 	.vmap = drm_gem_dmabuf_vmap,
790 	.vunmap = drm_gem_dmabuf_vunmap,
791 };
792 
793 /**
794  * drm_prime_pages_to_sg - converts a page array into an sg list
795  * @dev: DRM device
796  * @pages: pointer to the array of page pointers to convert
797  * @nr_pages: length of the page vector
798  *
799  * This helper creates an sg table object from a set of pages
800  * the driver is responsible for mapping the pages into the
801  * importers address space for use with dma_buf itself.
802  *
803  * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
804  */
drm_prime_pages_to_sg(struct drm_device * dev,struct page ** pages,unsigned int nr_pages)805 struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
806 				       struct page **pages, unsigned int nr_pages)
807 {
808 	struct sg_table *sg;
809 	size_t max_segment = 0;
810 	int err;
811 
812 	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
813 	if (!sg)
814 		return ERR_PTR(-ENOMEM);
815 
816 	if (dev)
817 		max_segment = dma_max_mapping_size(dev->dev);
818 	if (max_segment == 0)
819 		max_segment = UINT_MAX;
820 	err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0,
821 						nr_pages << PAGE_SHIFT,
822 						max_segment, GFP_KERNEL);
823 	if (err) {
824 		kfree(sg);
825 		sg = ERR_PTR(err);
826 	}
827 	return sg;
828 }
829 EXPORT_SYMBOL(drm_prime_pages_to_sg);
830 
831 /**
832  * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
833  * @sgt: sg_table describing the buffer to check
834  *
835  * This helper calculates the contiguous size in the DMA address space
836  * of the buffer described by the provided sg_table.
837  *
838  * This is useful for implementing
839  * &drm_gem_object_funcs.gem_prime_import_sg_table.
840  */
drm_prime_get_contiguous_size(struct sg_table * sgt)841 unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
842 {
843 	dma_addr_t expected = sg_dma_address(sgt->sgl);
844 	struct scatterlist *sg;
845 	unsigned long size = 0;
846 	int i;
847 
848 	for_each_sgtable_dma_sg(sgt, sg, i) {
849 		unsigned int len = sg_dma_len(sg);
850 
851 		if (!len)
852 			break;
853 		if (sg_dma_address(sg) != expected)
854 			break;
855 		expected += len;
856 		size += len;
857 	}
858 	return size;
859 }
860 EXPORT_SYMBOL(drm_prime_get_contiguous_size);
861 
862 /**
863  * drm_gem_prime_export - helper library implementation of the export callback
864  * @obj: GEM object to export
865  * @flags: flags like DRM_CLOEXEC and DRM_RDWR
866  *
867  * This is the implementation of the &drm_gem_object_funcs.export functions
868  * for GEM drivers using the PRIME helpers. It is used as the default for
869  * drivers that do not set their own.
870  */
drm_gem_prime_export(struct drm_gem_object * obj,int flags)871 struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
872 				     int flags)
873 {
874 	struct drm_device *dev = obj->dev;
875 	struct dma_buf_export_info exp_info = {
876 		.exp_name = KBUILD_MODNAME, /* white lie for debug */
877 		.owner = dev->driver->fops->owner,
878 		.ops = &drm_gem_prime_dmabuf_ops,
879 		.size = obj->size,
880 		.flags = flags,
881 		.priv = obj,
882 		.resv = obj->resv,
883 	};
884 
885 	return drm_gem_dmabuf_export(dev, &exp_info);
886 }
887 EXPORT_SYMBOL(drm_gem_prime_export);
888 
889 /**
890  * drm_gem_prime_import_dev - core implementation of the import callback
891  * @dev: drm_device to import into
892  * @dma_buf: dma-buf object to import
893  * @attach_dev: struct device to dma_buf attach
894  *
895  * This is the core of drm_gem_prime_import(). It's designed to be called by
896  * drivers who want to use a different device structure than &drm_device.dev for
897  * attaching via dma_buf. This function calls
898  * &drm_driver.gem_prime_import_sg_table internally.
899  *
900  * Drivers must arrange to call drm_prime_gem_destroy() from their
901  * &drm_gem_object_funcs.free hook when using this function.
902  */
drm_gem_prime_import_dev(struct drm_device * dev,struct dma_buf * dma_buf,struct device * attach_dev)903 struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
904 					    struct dma_buf *dma_buf,
905 					    struct device *attach_dev)
906 {
907 	struct dma_buf_attachment *attach;
908 	struct sg_table *sgt;
909 	struct drm_gem_object *obj;
910 	int ret;
911 
912 	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
913 		obj = dma_buf->priv;
914 		if (obj->dev == dev) {
915 			/*
916 			 * Importing dmabuf exported from our own gem increases
917 			 * refcount on gem itself instead of f_count of dmabuf.
918 			 */
919 			drm_gem_object_get(obj);
920 			return obj;
921 		}
922 	}
923 
924 	if (!dev->driver->gem_prime_import_sg_table)
925 		return ERR_PTR(-EINVAL);
926 
927 	attach = dma_buf_attach(dma_buf, attach_dev);
928 	if (IS_ERR(attach))
929 		return ERR_CAST(attach);
930 
931 	get_dma_buf(dma_buf);
932 
933 	sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
934 	if (IS_ERR(sgt)) {
935 		ret = PTR_ERR(sgt);
936 		goto fail_detach;
937 	}
938 
939 	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
940 	if (IS_ERR(obj)) {
941 		ret = PTR_ERR(obj);
942 		goto fail_unmap;
943 	}
944 
945 	obj->import_attach = attach;
946 	obj->resv = dma_buf->resv;
947 
948 	return obj;
949 
950 fail_unmap:
951 	dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
952 fail_detach:
953 	dma_buf_detach(dma_buf, attach);
954 	dma_buf_put(dma_buf);
955 
956 	return ERR_PTR(ret);
957 }
958 EXPORT_SYMBOL(drm_gem_prime_import_dev);
959 
960 /**
961  * drm_gem_prime_import - helper library implementation of the import callback
962  * @dev: drm_device to import into
963  * @dma_buf: dma-buf object to import
964  *
965  * This is the implementation of the gem_prime_import functions for GEM
966  * drivers using the PRIME helpers. It is the default for drivers that do
967  * not set their own &drm_driver.gem_prime_import.
968  *
969  * Drivers must arrange to call drm_prime_gem_destroy() from their
970  * &drm_gem_object_funcs.free hook when using this function.
971  */
drm_gem_prime_import(struct drm_device * dev,struct dma_buf * dma_buf)972 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
973 					    struct dma_buf *dma_buf)
974 {
975 	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
976 }
977 EXPORT_SYMBOL(drm_gem_prime_import);
978 
979 /**
980  * drm_prime_sg_to_page_array - convert an sg table into a page array
981  * @sgt: scatter-gather table to convert
982  * @pages: array of page pointers to store the pages in
983  * @max_entries: size of the passed-in array
984  *
985  * Exports an sg table into an array of pages.
986  *
987  * This function is deprecated and strongly discouraged to be used.
988  * The page array is only useful for page faults and those can corrupt fields
989  * in the struct page if they are not handled by the exporting driver.
990  */
drm_prime_sg_to_page_array(struct sg_table * sgt,struct page ** pages,int max_entries)991 int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
992 					    struct page **pages,
993 					    int max_entries)
994 {
995 	struct sg_page_iter page_iter;
996 	struct page **p = pages;
997 
998 	for_each_sgtable_page(sgt, &page_iter, 0) {
999 		if (WARN_ON(p - pages >= max_entries))
1000 			return -1;
1001 		*p++ = sg_page_iter_page(&page_iter);
1002 	}
1003 	return 0;
1004 }
1005 EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1006 
1007 /**
1008  * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1009  * @sgt: scatter-gather table to convert
1010  * @addrs: array to store the dma bus address of each page
1011  * @max_entries: size of both the passed-in arrays
1012  *
1013  * Exports an sg table into an array of addresses.
1014  *
1015  * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1016  * implementation.
1017  */
drm_prime_sg_to_dma_addr_array(struct sg_table * sgt,dma_addr_t * addrs,int max_entries)1018 int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1019 				   int max_entries)
1020 {
1021 	struct sg_dma_page_iter dma_iter;
1022 	dma_addr_t *a = addrs;
1023 
1024 	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1025 		if (WARN_ON(a - addrs >= max_entries))
1026 			return -1;
1027 		*a++ = sg_page_iter_dma_address(&dma_iter);
1028 	}
1029 	return 0;
1030 }
1031 EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1032 
1033 /**
1034  * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1035  * @obj: GEM object which was created from a dma-buf
1036  * @sg: the sg-table which was pinned at import time
1037  *
1038  * This is the cleanup functions which GEM drivers need to call when they use
1039  * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1040  */
drm_prime_gem_destroy(struct drm_gem_object * obj,struct sg_table * sg)1041 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1042 {
1043 	struct dma_buf_attachment *attach;
1044 	struct dma_buf *dma_buf;
1045 
1046 	attach = obj->import_attach;
1047 	if (sg)
1048 		dma_buf_unmap_attachment_unlocked(attach, sg, DMA_BIDIRECTIONAL);
1049 	dma_buf = attach->dmabuf;
1050 	dma_buf_detach(attach->dmabuf, attach);
1051 	/* remove the reference */
1052 	dma_buf_put(dma_buf);
1053 }
1054 EXPORT_SYMBOL(drm_prime_gem_destroy);
1055