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>
34 * DMA-BUF/GEM Object references and lifetime overview:
36 * On the export the dma_buf holds a reference to the exporting GEM
37 * object. It takes this reference in handle_to_fd_ioctl, when it
38 * first calls .prime_export and stores the exporting GEM object in
39 * the dma_buf priv. This reference is released when the dma_buf
40 * object goes away in the driver .release function.
42 * On the import the importing GEM object holds a reference to the
43 * dma_buf (which in turn holds a ref to the exporting GEM object).
44 * It takes that reference in the fd_to_handle ioctl.
45 * It calls dma_buf_get, creates an attachment to it and stores the
46 * attachment in the GEM object. When this attachment is destroyed
47 * when the imported object is destroyed, we remove the attachment
48 * and drop the reference to the dma_buf.
50 * Thus the chain of references always flows in one direction
51 * (avoiding loops): importing_gem -> dmabuf -> exporting_gem
53 * Self-importing: if userspace is using PRIME as a replacement for flink
54 * then it will get a fd->handle request for a GEM object that it created.
55 * Drivers should detect this situation and return back the gem object
56 * from the dma-buf private. Prime will do this automatically for drivers that
57 * use the drm_gem_prime_{import,export} helpers.
60 struct drm_prime_member {
61 struct list_head entry;
62 struct dma_buf *dma_buf;
66 bool drm_prime_check_dmabuf_valid(struct dma_buf *dmabuf)
68 struct file *file = dmabuf->file;
71 * There could be a race when drm_gem_prime_handle_to_fd() is requested
72 * during __fput() is executed with same dmabuf.
73 * Let's suppose that there are process A and B. A creates a gem obj
74 * and exports it to dmabuf, B opens gem name which comes from A.
75 * And A is closing dmabuf and B tries to import dmabuf at that time.
76 * In this case, the dmabuf is in obj->export_dma_buf cache, because
77 * gem obj is still valid, and B could get dmabuf from this cache,
78 * but this dmabuf is invalid already, so B has to get a new dmabuf
81 if (!atomic_long_read(&file->f_count))
86 EXPORT_SYMBOL(drm_prime_check_dmabuf_valid);
88 static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
89 enum dma_data_direction dir)
91 struct drm_gem_object *obj = attach->dmabuf->priv;
94 mutex_lock(&obj->dev->struct_mutex);
96 sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
98 if (!IS_ERR_OR_NULL(sgt))
99 dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);
101 mutex_unlock(&obj->dev->struct_mutex);
105 static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
106 struct sg_table *sgt, enum dma_data_direction dir)
108 dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
113 static void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
115 struct drm_gem_object *obj = dma_buf->priv;
117 if (obj->export_dma_buf == dma_buf) {
118 /* drop the reference on the export fd holds */
119 obj->export_dma_buf = NULL;
120 drm_gem_object_unreference_unlocked(obj);
124 static void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
126 struct drm_gem_object *obj = dma_buf->priv;
127 struct drm_device *dev = obj->dev;
129 return dev->driver->gem_prime_vmap(obj);
132 static void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
134 struct drm_gem_object *obj = dma_buf->priv;
135 struct drm_device *dev = obj->dev;
137 dev->driver->gem_prime_vunmap(obj, vaddr);
140 static void *drm_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
141 unsigned long page_num)
146 static void drm_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
147 unsigned long page_num, void *addr)
151 static void *drm_gem_dmabuf_kmap(struct dma_buf *dma_buf,
152 unsigned long page_num)
157 static void drm_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
158 unsigned long page_num, void *addr)
163 static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
164 struct vm_area_struct *vma)
169 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
170 .map_dma_buf = drm_gem_map_dma_buf,
171 .unmap_dma_buf = drm_gem_unmap_dma_buf,
172 .release = drm_gem_dmabuf_release,
173 .kmap = drm_gem_dmabuf_kmap,
174 .kmap_atomic = drm_gem_dmabuf_kmap_atomic,
175 .kunmap = drm_gem_dmabuf_kunmap,
176 .kunmap_atomic = drm_gem_dmabuf_kunmap_atomic,
177 .mmap = drm_gem_dmabuf_mmap,
178 .vmap = drm_gem_dmabuf_vmap,
179 .vunmap = drm_gem_dmabuf_vunmap,
185 * Drivers can implement @gem_prime_export and @gem_prime_import in terms of
186 * simpler APIs by using the helper functions @drm_gem_prime_export and
187 * @drm_gem_prime_import. These functions implement dma-buf support in terms of
188 * five lower-level driver callbacks:
192 * - @gem_prime_pin (optional): prepare a GEM object for exporting
194 * - @gem_prime_get_sg_table: provide a scatter/gather table of pinned pages
196 * - @gem_prime_vmap: vmap a buffer exported by your driver
198 * - @gem_prime_vunmap: vunmap a buffer exported by your driver
202 * - @gem_prime_import_sg_table (import): produce a GEM object from another
203 * driver's scatter/gather table
206 struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
207 struct drm_gem_object *obj, int flags)
209 if (dev->driver->gem_prime_pin) {
210 int ret = dev->driver->gem_prime_pin(obj);
214 return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size, flags);
216 EXPORT_SYMBOL(drm_gem_prime_export);
218 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
219 struct drm_file *file_priv, uint32_t handle, uint32_t flags,
222 struct drm_gem_object *obj;
225 struct dma_buf *dmabuf;
227 obj = drm_gem_object_lookup(dev, file_priv, handle);
231 mutex_lock(&file_priv->prime.lock);
232 /* re-export the original imported object */
233 if (obj->import_attach) {
234 dmabuf = obj->import_attach->dmabuf;
238 if (obj->export_dma_buf) {
239 dmabuf = obj->export_dma_buf;
243 buf = dev->driver->gem_prime_export(dev, obj, flags);
245 /* normally the created dma-buf takes ownership of the ref,
246 * but if that fails then drop the ref
251 obj->export_dma_buf = buf;
253 /* if we've exported this buffer the cheat and add it to the import list
254 * so we get the correct handle back
256 ret = drm_prime_add_buf_handle(&file_priv->prime,
257 obj->export_dma_buf, handle);
261 *prime_fd = dma_buf_fd(buf, flags);
262 mutex_unlock(&file_priv->prime.lock);
267 *prime_fd = dma_buf_fd(dmabuf, flags);
269 drm_gem_object_unreference_unlocked(obj);
270 mutex_unlock(&file_priv->prime.lock);
273 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
275 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
276 struct dma_buf *dma_buf)
278 struct dma_buf_attachment *attach;
279 struct sg_table *sgt;
280 struct drm_gem_object *obj;
283 if (!dev->driver->gem_prime_import_sg_table)
284 return ERR_PTR(-EINVAL);
286 if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
288 if (obj->dev == dev) {
290 * Importing dmabuf exported from out own gem increases
291 * refcount on gem itself instead of f_count of dmabuf.
293 drm_gem_object_reference(obj);
298 attach = dma_buf_attach(dma_buf, dev->dev);
300 return ERR_PTR(PTR_ERR(attach));
302 get_dma_buf(dma_buf);
304 sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
305 if (IS_ERR_OR_NULL(sgt)) {
310 obj = dev->driver->gem_prime_import_sg_table(dev, dma_buf->size, sgt);
316 obj->import_attach = attach;
321 dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
323 dma_buf_detach(dma_buf, attach);
324 dma_buf_put(dma_buf);
328 EXPORT_SYMBOL(drm_gem_prime_import);
330 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
331 struct drm_file *file_priv, int prime_fd, uint32_t *handle)
333 struct dma_buf *dma_buf;
334 struct drm_gem_object *obj;
337 dma_buf = dma_buf_get(prime_fd);
339 return PTR_ERR(dma_buf);
341 mutex_lock(&file_priv->prime.lock);
343 ret = drm_prime_lookup_buf_handle(&file_priv->prime,
350 /* never seen this one, need to import */
351 obj = dev->driver->gem_prime_import(dev, dma_buf);
357 ret = drm_gem_handle_create(file_priv, obj, handle);
358 drm_gem_object_unreference_unlocked(obj);
362 ret = drm_prime_add_buf_handle(&file_priv->prime,
367 mutex_unlock(&file_priv->prime.lock);
369 dma_buf_put(dma_buf);
374 /* hmm, if driver attached, we are relying on the free-object path
375 * to detach.. which seems ok..
377 drm_gem_object_handle_unreference_unlocked(obj);
379 dma_buf_put(dma_buf);
380 mutex_unlock(&file_priv->prime.lock);
383 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
385 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
386 struct drm_file *file_priv)
388 struct drm_prime_handle *args = data;
391 if (!drm_core_check_feature(dev, DRIVER_PRIME))
394 if (!dev->driver->prime_handle_to_fd)
397 /* check flags are valid */
398 if (args->flags & ~DRM_CLOEXEC)
401 /* we only want to pass DRM_CLOEXEC which is == O_CLOEXEC */
402 flags = args->flags & DRM_CLOEXEC;
404 return dev->driver->prime_handle_to_fd(dev, file_priv,
405 args->handle, flags, &args->fd);
408 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
409 struct drm_file *file_priv)
411 struct drm_prime_handle *args = data;
413 if (!drm_core_check_feature(dev, DRIVER_PRIME))
416 if (!dev->driver->prime_fd_to_handle)
419 return dev->driver->prime_fd_to_handle(dev, file_priv,
420 args->fd, &args->handle);
424 * drm_prime_pages_to_sg
426 * this helper creates an sg table object from a set of pages
427 * the driver is responsible for mapping the pages into the
428 * importers address space
430 struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages)
432 struct sg_table *sg = NULL;
435 sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
439 ret = sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
440 nr_pages << PAGE_SHIFT, GFP_KERNEL);
449 EXPORT_SYMBOL(drm_prime_pages_to_sg);
451 /* export an sg table into an array of pages and addresses
452 this is currently required by the TTM driver in order to do correct fault
454 int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
455 dma_addr_t *addrs, int max_pages)
458 struct scatterlist *sg;
465 for_each_sg(sgt->sgl, sg, sgt->nents, count) {
469 addr = sg_dma_address(sg);
472 if (WARN_ON(pg_index >= max_pages))
474 pages[pg_index] = page;
476 addrs[pg_index] = addr;
486 EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
487 /* helper function to cleanup a GEM/prime object */
488 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
490 struct dma_buf_attachment *attach;
491 struct dma_buf *dma_buf;
492 attach = obj->import_attach;
494 dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
495 dma_buf = attach->dmabuf;
496 dma_buf_detach(attach->dmabuf, attach);
497 /* remove the reference */
498 dma_buf_put(dma_buf);
500 EXPORT_SYMBOL(drm_prime_gem_destroy);
502 void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
504 INIT_LIST_HEAD(&prime_fpriv->head);
505 mutex_init(&prime_fpriv->lock);
507 EXPORT_SYMBOL(drm_prime_init_file_private);
509 void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
511 /* by now drm_gem_release should've made sure the list is empty */
512 WARN_ON(!list_empty(&prime_fpriv->head));
514 EXPORT_SYMBOL(drm_prime_destroy_file_private);
516 int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle)
518 struct drm_prime_member *member;
520 member = kmalloc(sizeof(*member), GFP_KERNEL);
524 get_dma_buf(dma_buf);
525 member->dma_buf = dma_buf;
526 member->handle = handle;
527 list_add(&member->entry, &prime_fpriv->head);
530 EXPORT_SYMBOL(drm_prime_add_buf_handle);
532 int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle)
534 struct drm_prime_member *member;
536 list_for_each_entry(member, &prime_fpriv->head, entry) {
537 if (member->dma_buf == dma_buf) {
538 *handle = member->handle;
544 EXPORT_SYMBOL(drm_prime_lookup_buf_handle);
546 void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf)
548 struct drm_prime_member *member, *safe;
550 mutex_lock(&prime_fpriv->lock);
551 list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
552 if (member->dma_buf == dma_buf) {
553 dma_buf_put(dma_buf);
554 list_del(&member->entry);
558 mutex_unlock(&prime_fpriv->lock);
560 EXPORT_SYMBOL(drm_prime_remove_buf_handle);