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  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 "drmP.h"
 32
 33/*
 34 * DMA-BUF/GEM Object references and lifetime overview:
 35 *
 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.
 41 *
 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.
 49 *
 50 * Thus the chain of references always flows in one direction
 51 * (avoiding loops): importing_gem -> dmabuf -> exporting_gem
 52 *
 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.
 57 */
 58
 59struct drm_prime_member {
 60	struct list_head entry;
 61	struct dma_buf *dma_buf;
 62	uint32_t handle;
 63};
 64
 65int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 66		struct drm_file *file_priv, uint32_t handle, uint32_t flags,
 67		int *prime_fd)
 68{
 69	struct drm_gem_object *obj;
 70	void *buf;
 71	int ret;
 72
 73	obj = drm_gem_object_lookup(dev, file_priv, handle);
 74	if (!obj)
 75		return -ENOENT;
 76
 77	mutex_lock(&file_priv->prime.lock);
 78	/* re-export the original imported object */
 79	if (obj->import_attach) {
 80		get_dma_buf(obj->import_attach->dmabuf);
 81		*prime_fd = dma_buf_fd(obj->import_attach->dmabuf, flags);
 82		drm_gem_object_unreference_unlocked(obj);
 83		mutex_unlock(&file_priv->prime.lock);
 84		return 0;
 85	}
 86
 87	if (obj->export_dma_buf) {
 88		get_dma_buf(obj->export_dma_buf);
 89		*prime_fd = dma_buf_fd(obj->export_dma_buf, flags);
 90		drm_gem_object_unreference_unlocked(obj);
 91	} else {
 92		buf = dev->driver->gem_prime_export(dev, obj, flags);
 93		if (IS_ERR(buf)) {
 94			/* normally the created dma-buf takes ownership of the ref,
 95			 * but if that fails then drop the ref
 96			 */
 97			drm_gem_object_unreference_unlocked(obj);
 98			mutex_unlock(&file_priv->prime.lock);
 99			return PTR_ERR(buf);
100		}
101		obj->export_dma_buf = buf;
102		*prime_fd = dma_buf_fd(buf, flags);
103	}
104	/* if we've exported this buffer the cheat and add it to the import list
105	 * so we get the correct handle back
106	 */
107	ret = drm_prime_add_imported_buf_handle(&file_priv->prime,
108			obj->export_dma_buf, handle);
109	if (ret) {
110		drm_gem_object_unreference_unlocked(obj);
111		mutex_unlock(&file_priv->prime.lock);
112		return ret;
113	}
114
115	mutex_unlock(&file_priv->prime.lock);
116	return 0;
117}
118EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
119
120int drm_gem_prime_fd_to_handle(struct drm_device *dev,
121		struct drm_file *file_priv, int prime_fd, uint32_t *handle)
122{
123	struct dma_buf *dma_buf;
124	struct drm_gem_object *obj;
125	int ret;
126
127	dma_buf = dma_buf_get(prime_fd);
128	if (IS_ERR(dma_buf))
129		return PTR_ERR(dma_buf);
130
131	mutex_lock(&file_priv->prime.lock);
132
133	ret = drm_prime_lookup_imported_buf_handle(&file_priv->prime,
134			dma_buf, handle);
135	if (!ret) {
136		ret = 0;
137		goto out_put;
138	}
139
140	/* never seen this one, need to import */
141	obj = dev->driver->gem_prime_import(dev, dma_buf);
142	if (IS_ERR(obj)) {
143		ret = PTR_ERR(obj);
144		goto out_put;
145	}
146
147	ret = drm_gem_handle_create(file_priv, obj, handle);
148	drm_gem_object_unreference_unlocked(obj);
149	if (ret)
150		goto out_put;
151
152	ret = drm_prime_add_imported_buf_handle(&file_priv->prime,
153			dma_buf, *handle);
154	if (ret)
155		goto fail;
156
157	mutex_unlock(&file_priv->prime.lock);
158	return 0;
159
160fail:
161	/* hmm, if driver attached, we are relying on the free-object path
162	 * to detach.. which seems ok..
163	 */
164	drm_gem_object_handle_unreference_unlocked(obj);
165out_put:
166	dma_buf_put(dma_buf);
167	mutex_unlock(&file_priv->prime.lock);
168	return ret;
169}
170EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
171
172int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
173				 struct drm_file *file_priv)
174{
175	struct drm_prime_handle *args = data;
176	uint32_t flags;
177
178	if (!drm_core_check_feature(dev, DRIVER_PRIME))
179		return -EINVAL;
180
181	if (!dev->driver->prime_handle_to_fd)
182		return -ENOSYS;
183
184	/* check flags are valid */
185	if (args->flags & ~DRM_CLOEXEC)
186		return -EINVAL;
187
188	/* we only want to pass DRM_CLOEXEC which is == O_CLOEXEC */
189	flags = args->flags & DRM_CLOEXEC;
190
191	return dev->driver->prime_handle_to_fd(dev, file_priv,
192			args->handle, flags, &args->fd);
193}
194
195int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
196				 struct drm_file *file_priv)
197{
198	struct drm_prime_handle *args = data;
199
200	if (!drm_core_check_feature(dev, DRIVER_PRIME))
201		return -EINVAL;
202
203	if (!dev->driver->prime_fd_to_handle)
204		return -ENOSYS;
205
206	return dev->driver->prime_fd_to_handle(dev, file_priv,
207			args->fd, &args->handle);
208}
209
210/*
211 * drm_prime_pages_to_sg
212 *
213 * this helper creates an sg table object from a set of pages
214 * the driver is responsible for mapping the pages into the
215 * importers address space
216 */
217struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages)
218{
219	struct sg_table *sg = NULL;
220	struct scatterlist *iter;
221	int i;
222	int ret;
223
224	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
225	if (!sg)
226		goto out;
227
228	ret = sg_alloc_table(sg, nr_pages, GFP_KERNEL);
229	if (ret)
230		goto out;
231
232	for_each_sg(sg->sgl, iter, nr_pages, i)
233		sg_set_page(iter, pages[i], PAGE_SIZE, 0);
234
235	return sg;
236out:
237	kfree(sg);
238	return NULL;
239}
240EXPORT_SYMBOL(drm_prime_pages_to_sg);
241
242/* export an sg table into an array of pages and addresses
243   this is currently required by the TTM driver in order to do correct fault
244   handling */
245int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
246				     dma_addr_t *addrs, int max_pages)
247{
248	unsigned count;
249	struct scatterlist *sg;
250	struct page *page;
251	u32 len, offset;
252	int pg_index;
253	dma_addr_t addr;
254
255	pg_index = 0;
256	for_each_sg(sgt->sgl, sg, sgt->nents, count) {
257		len = sg->length;
258		offset = sg->offset;
259		page = sg_page(sg);
260		addr = sg_dma_address(sg);
261
262		while (len > 0) {
263			if (WARN_ON(pg_index >= max_pages))
264				return -1;
265			pages[pg_index] = page;
266			if (addrs)
267				addrs[pg_index] = addr;
268
269			page++;
270			addr += PAGE_SIZE;
271			len -= PAGE_SIZE;
272			pg_index++;
273		}
274	}
275	return 0;
276}
277EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
278/* helper function to cleanup a GEM/prime object */
279void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
280{
281	struct dma_buf_attachment *attach;
282	struct dma_buf *dma_buf;
283	attach = obj->import_attach;
284	if (sg)
285		dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
286	dma_buf = attach->dmabuf;
287	dma_buf_detach(attach->dmabuf, attach);
288	/* remove the reference */
289	dma_buf_put(dma_buf);
290}
291EXPORT_SYMBOL(drm_prime_gem_destroy);
292
293void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
294{
295	INIT_LIST_HEAD(&prime_fpriv->head);
296	mutex_init(&prime_fpriv->lock);
297}
298EXPORT_SYMBOL(drm_prime_init_file_private);
299
300void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
301{
302	struct drm_prime_member *member, *safe;
303	list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
304		list_del(&member->entry);
305		kfree(member);
306	}
307}
308EXPORT_SYMBOL(drm_prime_destroy_file_private);
309
310int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle)
311{
312	struct drm_prime_member *member;
313
314	member = kmalloc(sizeof(*member), GFP_KERNEL);
315	if (!member)
316		return -ENOMEM;
317
318	member->dma_buf = dma_buf;
319	member->handle = handle;
320	list_add(&member->entry, &prime_fpriv->head);
321	return 0;
322}
323EXPORT_SYMBOL(drm_prime_add_imported_buf_handle);
324
325int drm_prime_lookup_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle)
326{
327	struct drm_prime_member *member;
328
329	list_for_each_entry(member, &prime_fpriv->head, entry) {
330		if (member->dma_buf == dma_buf) {
331			*handle = member->handle;
332			return 0;
333		}
334	}
335	return -ENOENT;
336}
337EXPORT_SYMBOL(drm_prime_lookup_imported_buf_handle);
338
339void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf)
340{
341	struct drm_prime_member *member, *safe;
342
343	mutex_lock(&prime_fpriv->lock);
344	list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
345		if (member->dma_buf == dma_buf) {
346			list_del(&member->entry);
347			kfree(member);
348		}
349	}
350	mutex_unlock(&prime_fpriv->lock);
351}
352EXPORT_SYMBOL(drm_prime_remove_imported_buf_handle);