2 * Copyright © 2012 Red Hat
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:
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
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
24 * Dave Airlie <airlied@redhat.com>
25 * Rob Clark <rob.clark@linaro.org>
29 #include <linux/export.h>
30 #include <linux/dma-buf.h>
32 #include "drm_internal.h"
35 * DMA-BUF/GEM Object references and lifetime overview:
37 * On the export the dma_buf holds a reference to the exporting GEM
38 * object. It takes this reference in handle_to_fd_ioctl, when it
39 * first calls .prime_export and stores the exporting GEM object in
40 * the dma_buf priv. This reference is released when the dma_buf
41 * object goes away in the driver .release function.
43 * On the import the importing GEM object holds a reference to the
44 * dma_buf (which in turn holds a ref to the exporting GEM object).
45 * It takes that reference in the fd_to_handle ioctl.
46 * It calls dma_buf_get, creates an attachment to it and stores the
47 * attachment in the GEM object. When this attachment is destroyed
48 * when the imported object is destroyed, we remove the attachment
49 * and drop the reference to the dma_buf.
51 * Thus the chain of references always flows in one direction
52 * (avoiding loops): importing_gem -> dmabuf -> exporting_gem
54 * Self-importing: if userspace is using PRIME as a replacement for flink
55 * then it will get a fd->handle request for a GEM object that it created.
56 * Drivers should detect this situation and return back the gem object
57 * from the dma-buf private. Prime will do this automatically for drivers that
58 * use the drm_gem_prime_{import,export} helpers.
61 struct drm_prime_member {
62 struct list_head entry;
63 struct dma_buf *dma_buf;
67 struct drm_prime_attachment {
69 enum dma_data_direction dir;
72 static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
73 struct dma_buf *dma_buf, uint32_t handle)
75 struct drm_prime_member *member;
77 member = kmalloc(sizeof(*member), GFP_KERNEL);
82 member->dma_buf = dma_buf;
83 member->handle = handle;
84 list_add(&member->entry, &prime_fpriv->head);
88 static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
91 struct drm_prime_member *member;
93 list_for_each_entry(member, &prime_fpriv->head, entry) {
94 if (member->handle == handle)
95 return member->dma_buf;
101 static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
102 struct dma_buf *dma_buf,
105 struct drm_prime_member *member;
107 list_for_each_entry(member, &prime_fpriv->head, entry) {
108 if (member->dma_buf == dma_buf) {
109 *handle = member->handle;
116 static int drm_gem_map_attach(struct dma_buf *dma_buf,
117 struct device *target_dev,
118 struct dma_buf_attachment *attach)
120 struct drm_prime_attachment *prime_attach;
121 struct drm_gem_object *obj = dma_buf->priv;
122 struct drm_device *dev = obj->dev;
124 prime_attach = kzalloc(sizeof(*prime_attach), GFP_KERNEL);
128 prime_attach->dir = DMA_NONE;
129 attach->priv = prime_attach;
131 if (!dev->driver->gem_prime_pin)
134 return dev->driver->gem_prime_pin(obj);
137 static void drm_gem_map_detach(struct dma_buf *dma_buf,
138 struct dma_buf_attachment *attach)
140 struct drm_prime_attachment *prime_attach = attach->priv;
141 struct drm_gem_object *obj = dma_buf->priv;
142 struct drm_device *dev = obj->dev;
143 struct sg_table *sgt;
145 if (dev->driver->gem_prime_unpin)
146 dev->driver->gem_prime_unpin(obj);
151 sgt = prime_attach->sgt;
153 if (prime_attach->dir != DMA_NONE)
154 dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
164 void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv,
165 struct dma_buf *dma_buf)
167 struct drm_prime_member *member, *safe;
169 list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
170 if (member->dma_buf == dma_buf) {
171 dma_buf_put(dma_buf);
172 list_del(&member->entry);
178 static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
179 enum dma_data_direction dir)
181 struct drm_prime_attachment *prime_attach = attach->priv;
182 struct drm_gem_object *obj = attach->dmabuf->priv;
183 struct sg_table *sgt;
185 if (WARN_ON(dir == DMA_NONE || !prime_attach))
186 return ERR_PTR(-EINVAL);
188 /* return the cached mapping when possible */
189 if (prime_attach->dir == dir)
190 return prime_attach->sgt;
193 * two mappings with different directions for the same attachment are
196 if (WARN_ON(prime_attach->dir != DMA_NONE))
197 return ERR_PTR(-EBUSY);
199 sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
202 if (!dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir)) {
205 sgt = ERR_PTR(-ENOMEM);
207 prime_attach->sgt = sgt;
208 prime_attach->dir = dir;
215 static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
216 struct sg_table *sgt,
217 enum dma_data_direction dir)
219 /* nothing to be done here */
223 * drm_gem_dmabuf_release - dma_buf release implementation for GEM
224 * @dma_buf: buffer to be released
226 * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
227 * must use this in their dma_buf ops structure as the release callback.
229 void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
231 struct drm_gem_object *obj = dma_buf->priv;
233 /* drop the reference on the export fd holds */
234 drm_gem_object_unreference_unlocked(obj);
236 EXPORT_SYMBOL(drm_gem_dmabuf_release);
238 static void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
240 struct drm_gem_object *obj = dma_buf->priv;
241 struct drm_device *dev = obj->dev;
243 return dev->driver->gem_prime_vmap(obj);
246 static void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
248 struct drm_gem_object *obj = dma_buf->priv;
249 struct drm_device *dev = obj->dev;
251 dev->driver->gem_prime_vunmap(obj, vaddr);
254 static void *drm_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
255 unsigned long page_num)
260 static void drm_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
261 unsigned long page_num, void *addr)
265 static void *drm_gem_dmabuf_kmap(struct dma_buf *dma_buf,
266 unsigned long page_num)
271 static void drm_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
272 unsigned long page_num, void *addr)
277 static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
278 struct vm_area_struct *vma)
280 struct drm_gem_object *obj = dma_buf->priv;
281 struct drm_device *dev = obj->dev;
283 if (!dev->driver->gem_prime_mmap)
286 return dev->driver->gem_prime_mmap(obj, vma);
289 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
290 .attach = drm_gem_map_attach,
291 .detach = drm_gem_map_detach,
292 .map_dma_buf = drm_gem_map_dma_buf,
293 .unmap_dma_buf = drm_gem_unmap_dma_buf,
294 .release = drm_gem_dmabuf_release,
295 .kmap = drm_gem_dmabuf_kmap,
296 .kmap_atomic = drm_gem_dmabuf_kmap_atomic,
297 .kunmap = drm_gem_dmabuf_kunmap,
298 .kunmap_atomic = drm_gem_dmabuf_kunmap_atomic,
299 .mmap = drm_gem_dmabuf_mmap,
300 .vmap = drm_gem_dmabuf_vmap,
301 .vunmap = drm_gem_dmabuf_vunmap,
307 * Drivers can implement @gem_prime_export and @gem_prime_import in terms of
308 * simpler APIs by using the helper functions @drm_gem_prime_export and
309 * @drm_gem_prime_import. These functions implement dma-buf support in terms of
310 * five lower-level driver callbacks:
314 * - @gem_prime_pin (optional): prepare a GEM object for exporting
316 * - @gem_prime_get_sg_table: provide a scatter/gather table of pinned pages
318 * - @gem_prime_vmap: vmap a buffer exported by your driver
320 * - @gem_prime_vunmap: vunmap a buffer exported by your driver
324 * - @gem_prime_import_sg_table (import): produce a GEM object from another
325 * driver's scatter/gather table
329 * drm_gem_prime_export - helper library implemention of the export callback
330 * @dev: drm_device to export from
331 * @obj: GEM object to export
332 * @flags: flags like DRM_CLOEXEC
334 * This is the implementation of the gem_prime_export functions for GEM drivers
335 * using the PRIME helpers.
337 struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
338 struct drm_gem_object *obj, int flags)
340 struct reservation_object *robj = NULL;
342 if (dev->driver->gem_prime_res_obj)
343 robj = dev->driver->gem_prime_res_obj(obj);
345 return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size,
348 EXPORT_SYMBOL(drm_gem_prime_export);
350 static struct dma_buf *export_and_register_object(struct drm_device *dev,
351 struct drm_gem_object *obj,
354 struct dma_buf *dmabuf;
356 /* prevent races with concurrent gem_close. */
357 if (obj->handle_count == 0) {
358 dmabuf = ERR_PTR(-ENOENT);
362 dmabuf = dev->driver->gem_prime_export(dev, obj, flags);
363 if (IS_ERR(dmabuf)) {
364 /* normally the created dma-buf takes ownership of the ref,
365 * but if that fails then drop the ref
371 * Note that callers do not need to clean up the export cache
372 * since the check for obj->handle_count guarantees that someone
375 obj->dma_buf = dmabuf;
376 get_dma_buf(obj->dma_buf);
377 /* Grab a new ref since the callers is now used by the dma-buf */
378 drm_gem_object_reference(obj);
384 * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
385 * @dev: dev to export the buffer from
386 * @file_priv: drm file-private structure
387 * @handle: buffer handle to export
388 * @flags: flags like DRM_CLOEXEC
389 * @prime_fd: pointer to storage for the fd id of the create dma-buf
391 * This is the PRIME export function which must be used mandatorily by GEM
392 * drivers to ensure correct lifetime management of the underlying GEM object.
393 * The actual exporting from GEM object to a dma-buf is done through the
394 * gem_prime_export driver callback.
396 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
397 struct drm_file *file_priv, uint32_t handle,
401 struct drm_gem_object *obj;
403 struct dma_buf *dmabuf;
405 mutex_lock(&file_priv->prime.lock);
406 obj = drm_gem_object_lookup(dev, file_priv, handle);
412 dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
415 goto out_have_handle;
418 mutex_lock(&dev->object_name_lock);
419 /* re-export the original imported object */
420 if (obj->import_attach) {
421 dmabuf = obj->import_attach->dmabuf;
427 get_dma_buf(obj->dma_buf);
428 dmabuf = obj->dma_buf;
432 dmabuf = export_and_register_object(dev, obj, flags);
433 if (IS_ERR(dmabuf)) {
434 /* normally the created dma-buf takes ownership of the ref,
435 * but if that fails then drop the ref
437 ret = PTR_ERR(dmabuf);
438 mutex_unlock(&dev->object_name_lock);
444 * If we've exported this buffer then cheat and add it to the import list
445 * so we get the correct handle back. We must do this under the
446 * protection of dev->object_name_lock to ensure that a racing gem close
447 * ioctl doesn't miss to remove this buffer handle from the cache.
449 ret = drm_prime_add_buf_handle(&file_priv->prime,
451 mutex_unlock(&dev->object_name_lock);
453 goto fail_put_dmabuf;
456 ret = dma_buf_fd(dmabuf, flags);
458 * We must _not_ remove the buffer from the handle cache since the newly
459 * created dma buf is already linked in the global obj->dma_buf pointer,
460 * and that is invariant as long as a userspace gem handle exists.
461 * Closing the handle will clean out the cache anyway, so we don't leak.
464 goto fail_put_dmabuf;
475 drm_gem_object_unreference_unlocked(obj);
477 mutex_unlock(&file_priv->prime.lock);
481 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
484 * drm_gem_prime_import - helper library implemention of the import callback
485 * @dev: drm_device to import into
486 * @dma_buf: dma-buf object to import
488 * This is the implementation of the gem_prime_import functions for GEM drivers
489 * using the PRIME helpers.
491 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
492 struct dma_buf *dma_buf)
494 struct dma_buf_attachment *attach;
495 struct sg_table *sgt;
496 struct drm_gem_object *obj;
499 if (!dev->driver->gem_prime_import_sg_table)
500 return ERR_PTR(-EINVAL);
502 if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
504 if (obj->dev == dev) {
506 * Importing dmabuf exported from out own gem increases
507 * refcount on gem itself instead of f_count of dmabuf.
509 drm_gem_object_reference(obj);
514 attach = dma_buf_attach(dma_buf, dev->dev);
516 return ERR_CAST(attach);
518 get_dma_buf(dma_buf);
520 sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
526 obj = dev->driver->gem_prime_import_sg_table(dev, dma_buf->size, sgt);
532 obj->import_attach = attach;
537 dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
539 dma_buf_detach(dma_buf, attach);
540 dma_buf_put(dma_buf);
544 EXPORT_SYMBOL(drm_gem_prime_import);
547 * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
548 * @dev: dev to export the buffer from
549 * @file_priv: drm file-private structure
550 * @prime_fd: fd id of the dma-buf which should be imported
551 * @handle: pointer to storage for the handle of the imported buffer object
553 * This is the PRIME import function which must be used mandatorily by GEM
554 * drivers to ensure correct lifetime management of the underlying GEM object.
555 * The actual importing of GEM object from the dma-buf is done through the
556 * gem_import_export driver callback.
558 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
559 struct drm_file *file_priv, int prime_fd,
562 struct dma_buf *dma_buf;
563 struct drm_gem_object *obj;
566 dma_buf = dma_buf_get(prime_fd);
568 return PTR_ERR(dma_buf);
570 mutex_lock(&file_priv->prime.lock);
572 ret = drm_prime_lookup_buf_handle(&file_priv->prime,
577 /* never seen this one, need to import */
578 mutex_lock(&dev->object_name_lock);
579 obj = dev->driver->gem_prime_import(dev, dma_buf);
586 WARN_ON(obj->dma_buf != dma_buf);
588 obj->dma_buf = dma_buf;
589 get_dma_buf(dma_buf);
592 /* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
593 ret = drm_gem_handle_create_tail(file_priv, obj, handle);
594 drm_gem_object_unreference_unlocked(obj);
598 ret = drm_prime_add_buf_handle(&file_priv->prime,
603 mutex_unlock(&file_priv->prime.lock);
605 dma_buf_put(dma_buf);
610 /* hmm, if driver attached, we are relying on the free-object path
611 * to detach.. which seems ok..
613 drm_gem_handle_delete(file_priv, *handle);
615 mutex_unlock(&dev->object_name_lock);
617 dma_buf_put(dma_buf);
618 mutex_unlock(&file_priv->prime.lock);
621 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
623 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
624 struct drm_file *file_priv)
626 struct drm_prime_handle *args = data;
629 if (!drm_core_check_feature(dev, DRIVER_PRIME))
632 if (!dev->driver->prime_handle_to_fd)
635 /* check flags are valid */
636 if (args->flags & ~DRM_CLOEXEC)
639 /* we only want to pass DRM_CLOEXEC which is == O_CLOEXEC */
640 flags = args->flags & DRM_CLOEXEC;
642 return dev->driver->prime_handle_to_fd(dev, file_priv,
643 args->handle, flags, &args->fd);
646 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
647 struct drm_file *file_priv)
649 struct drm_prime_handle *args = data;
651 if (!drm_core_check_feature(dev, DRIVER_PRIME))
654 if (!dev->driver->prime_fd_to_handle)
657 return dev->driver->prime_fd_to_handle(dev, file_priv,
658 args->fd, &args->handle);
662 * drm_prime_pages_to_sg - converts a page array into an sg list
663 * @pages: pointer to the array of page pointers to convert
664 * @nr_pages: length of the page vector
666 * This helper creates an sg table object from a set of pages
667 * the driver is responsible for mapping the pages into the
668 * importers address space for use with dma_buf itself.
670 struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages)
672 struct sg_table *sg = NULL;
675 sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
681 ret = sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
682 nr_pages << PAGE_SHIFT, GFP_KERNEL);
691 EXPORT_SYMBOL(drm_prime_pages_to_sg);
694 * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
695 * @sgt: scatter-gather table to convert
696 * @pages: array of page pointers to store the page array in
697 * @addrs: optional array to store the dma bus address of each page
698 * @max_pages: size of both the passed-in arrays
700 * Exports an sg table into an array of pages and addresses. This is currently
701 * required by the TTM driver in order to do correct fault handling.
703 int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
704 dma_addr_t *addrs, int max_pages)
707 struct scatterlist *sg;
714 for_each_sg(sgt->sgl, sg, sgt->nents, count) {
717 addr = sg_dma_address(sg);
720 if (WARN_ON(pg_index >= max_pages))
722 pages[pg_index] = page;
724 addrs[pg_index] = addr;
734 EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
737 * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
738 * @obj: GEM object which was created from a dma-buf
739 * @sg: the sg-table which was pinned at import time
741 * This is the cleanup functions which GEM drivers need to call when they use
742 * @drm_gem_prime_import to import dma-bufs.
744 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
746 struct dma_buf_attachment *attach;
747 struct dma_buf *dma_buf;
748 attach = obj->import_attach;
750 dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
751 dma_buf = attach->dmabuf;
752 dma_buf_detach(attach->dmabuf, attach);
753 /* remove the reference */
754 dma_buf_put(dma_buf);
756 EXPORT_SYMBOL(drm_prime_gem_destroy);
758 void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
760 INIT_LIST_HEAD(&prime_fpriv->head);
761 mutex_init(&prime_fpriv->lock);
764 void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
766 /* by now drm_gem_release should've made sure the list is empty */
767 WARN_ON(!list_empty(&prime_fpriv->head));