Root/drivers/gpu/drm/drm_prime.c

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);
353

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