Loading...
Note: File does not exist in v3.1.
1/*
2 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
3 * Copyright (c) 2012 David Airlie <airlied@linux.ie>
4 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
23 */
24
25#include <drm/drmP.h>
26#include <drm/drm_mm.h>
27#include <drm/drm_vma_manager.h>
28#include <linux/mm.h>
29#include <linux/module.h>
30#include <linux/rbtree.h>
31#include <linux/slab.h>
32#include <linux/spinlock.h>
33#include <linux/types.h>
34
35/**
36 * DOC: vma offset manager
37 *
38 * The vma-manager is responsible to map arbitrary driver-dependent memory
39 * regions into the linear user address-space. It provides offsets to the
40 * caller which can then be used on the address_space of the drm-device. It
41 * takes care to not overlap regions, size them appropriately and to not
42 * confuse mm-core by inconsistent fake vm_pgoff fields.
43 * Drivers shouldn't use this for object placement in VMEM. This manager should
44 * only be used to manage mappings into linear user-space VMs.
45 *
46 * We use drm_mm as backend to manage object allocations. But it is highly
47 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to
48 * speed up offset lookups.
49 *
50 * You must not use multiple offset managers on a single address_space.
51 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will
52 * no longer be linear.
53 *
54 * This offset manager works on page-based addresses. That is, every argument
55 * and return code (with the exception of drm_vma_node_offset_addr()) is given
56 * in number of pages, not number of bytes. That means, object sizes and offsets
57 * must always be page-aligned (as usual).
58 * If you want to get a valid byte-based user-space address for a given offset,
59 * please see drm_vma_node_offset_addr().
60 *
61 * Additionally to offset management, the vma offset manager also handles access
62 * management. For every open-file context that is allowed to access a given
63 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this
64 * open-file with the offset of the node will fail with -EACCES. To revoke
65 * access again, use drm_vma_node_revoke(). However, the caller is responsible
66 * for destroying already existing mappings, if required.
67 */
68
69/**
70 * drm_vma_offset_manager_init - Initialize new offset-manager
71 * @mgr: Manager object
72 * @page_offset: Offset of available memory area (page-based)
73 * @size: Size of available address space range (page-based)
74 *
75 * Initialize a new offset-manager. The offset and area size available for the
76 * manager are given as @page_offset and @size. Both are interpreted as
77 * page-numbers, not bytes.
78 *
79 * Adding/removing nodes from the manager is locked internally and protected
80 * against concurrent access. However, node allocation and destruction is left
81 * for the caller. While calling into the vma-manager, a given node must
82 * always be guaranteed to be referenced.
83 */
84void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
85 unsigned long page_offset, unsigned long size)
86{
87 rwlock_init(&mgr->vm_lock);
88 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);
89}
90EXPORT_SYMBOL(drm_vma_offset_manager_init);
91
92/**
93 * drm_vma_offset_manager_destroy() - Destroy offset manager
94 * @mgr: Manager object
95 *
96 * Destroy an object manager which was previously created via
97 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes
98 * before destroying the manager. Otherwise, drm_mm will refuse to free the
99 * requested resources.
100 *
101 * The manager must not be accessed after this function is called.
102 */
103void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
104{
105 /* take the lock to protect against buggy drivers */
106 write_lock(&mgr->vm_lock);
107 drm_mm_takedown(&mgr->vm_addr_space_mm);
108 write_unlock(&mgr->vm_lock);
109}
110EXPORT_SYMBOL(drm_vma_offset_manager_destroy);
111
112/**
113 * drm_vma_offset_lookup_locked() - Find node in offset space
114 * @mgr: Manager object
115 * @start: Start address for object (page-based)
116 * @pages: Size of object (page-based)
117 *
118 * Find a node given a start address and object size. This returns the _best_
119 * match for the given node. That is, @start may point somewhere into a valid
120 * region and the given node will be returned, as long as the node spans the
121 * whole requested area (given the size in number of pages as @pages).
122 *
123 * Note that before lookup the vma offset manager lookup lock must be acquired
124 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be
125 * used to implement weakly referenced lookups using kref_get_unless_zero().
126 *
127 * Example:
128 *
129 * ::
130 *
131 * drm_vma_offset_lock_lookup(mgr);
132 * node = drm_vma_offset_lookup_locked(mgr);
133 * if (node)
134 * kref_get_unless_zero(container_of(node, sth, entr));
135 * drm_vma_offset_unlock_lookup(mgr);
136 *
137 * RETURNS:
138 * Returns NULL if no suitable node can be found. Otherwise, the best match
139 * is returned. It's the caller's responsibility to make sure the node doesn't
140 * get destroyed before the caller can access it.
141 */
142struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
143 unsigned long start,
144 unsigned long pages)
145{
146 struct drm_mm_node *node, *best;
147 struct rb_node *iter;
148 unsigned long offset;
149
150 iter = mgr->vm_addr_space_mm.interval_tree.rb_node;
151 best = NULL;
152
153 while (likely(iter)) {
154 node = rb_entry(iter, struct drm_mm_node, rb);
155 offset = node->start;
156 if (start >= offset) {
157 iter = iter->rb_right;
158 best = node;
159 if (start == offset)
160 break;
161 } else {
162 iter = iter->rb_left;
163 }
164 }
165
166 /* verify that the node spans the requested area */
167 if (best) {
168 offset = best->start + best->size;
169 if (offset < start + pages)
170 best = NULL;
171 }
172
173 if (!best)
174 return NULL;
175
176 return container_of(best, struct drm_vma_offset_node, vm_node);
177}
178EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
179
180/**
181 * drm_vma_offset_add() - Add offset node to manager
182 * @mgr: Manager object
183 * @node: Node to be added
184 * @pages: Allocation size visible to user-space (in number of pages)
185 *
186 * Add a node to the offset-manager. If the node was already added, this does
187 * nothing and return 0. @pages is the size of the object given in number of
188 * pages.
189 * After this call succeeds, you can access the offset of the node until it
190 * is removed again.
191 *
192 * If this call fails, it is safe to retry the operation or call
193 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
194 * case.
195 *
196 * @pages is not required to be the same size as the underlying memory object
197 * that you want to map. It only limits the size that user-space can map into
198 * their address space.
199 *
200 * RETURNS:
201 * 0 on success, negative error code on failure.
202 */
203int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
204 struct drm_vma_offset_node *node, unsigned long pages)
205{
206 int ret;
207
208 write_lock(&mgr->vm_lock);
209
210 if (drm_mm_node_allocated(&node->vm_node)) {
211 ret = 0;
212 goto out_unlock;
213 }
214
215 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node,
216 pages, 0, DRM_MM_SEARCH_DEFAULT);
217 if (ret)
218 goto out_unlock;
219
220out_unlock:
221 write_unlock(&mgr->vm_lock);
222 return ret;
223}
224EXPORT_SYMBOL(drm_vma_offset_add);
225
226/**
227 * drm_vma_offset_remove() - Remove offset node from manager
228 * @mgr: Manager object
229 * @node: Node to be removed
230 *
231 * Remove a node from the offset manager. If the node wasn't added before, this
232 * does nothing. After this call returns, the offset and size will be 0 until a
233 * new offset is allocated via drm_vma_offset_add() again. Helper functions like
234 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
235 * offset is allocated.
236 */
237void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
238 struct drm_vma_offset_node *node)
239{
240 write_lock(&mgr->vm_lock);
241
242 if (drm_mm_node_allocated(&node->vm_node)) {
243 drm_mm_remove_node(&node->vm_node);
244 memset(&node->vm_node, 0, sizeof(node->vm_node));
245 }
246
247 write_unlock(&mgr->vm_lock);
248}
249EXPORT_SYMBOL(drm_vma_offset_remove);
250
251/**
252 * drm_vma_node_allow - Add open-file to list of allowed users
253 * @node: Node to modify
254 * @tag: Tag of file to remove
255 *
256 * Add @tag to the list of allowed open-files for this node. If @tag is
257 * already on this list, the ref-count is incremented.
258 *
259 * The list of allowed-users is preserved across drm_vma_offset_add() and
260 * drm_vma_offset_remove() calls. You may even call it if the node is currently
261 * not added to any offset-manager.
262 *
263 * You must remove all open-files the same number of times as you added them
264 * before destroying the node. Otherwise, you will leak memory.
265 *
266 * This is locked against concurrent access internally.
267 *
268 * RETURNS:
269 * 0 on success, negative error code on internal failure (out-of-mem)
270 */
271int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
272{
273 struct rb_node **iter;
274 struct rb_node *parent = NULL;
275 struct drm_vma_offset_file *new, *entry;
276 int ret = 0;
277
278 /* Preallocate entry to avoid atomic allocations below. It is quite
279 * unlikely that an open-file is added twice to a single node so we
280 * don't optimize for this case. OOM is checked below only if the entry
281 * is actually used. */
282 new = kmalloc(sizeof(*entry), GFP_KERNEL);
283
284 write_lock(&node->vm_lock);
285
286 iter = &node->vm_files.rb_node;
287
288 while (likely(*iter)) {
289 parent = *iter;
290 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);
291
292 if (tag == entry->vm_tag) {
293 entry->vm_count++;
294 goto unlock;
295 } else if (tag > entry->vm_tag) {
296 iter = &(*iter)->rb_right;
297 } else {
298 iter = &(*iter)->rb_left;
299 }
300 }
301
302 if (!new) {
303 ret = -ENOMEM;
304 goto unlock;
305 }
306
307 new->vm_tag = tag;
308 new->vm_count = 1;
309 rb_link_node(&new->vm_rb, parent, iter);
310 rb_insert_color(&new->vm_rb, &node->vm_files);
311 new = NULL;
312
313unlock:
314 write_unlock(&node->vm_lock);
315 kfree(new);
316 return ret;
317}
318EXPORT_SYMBOL(drm_vma_node_allow);
319
320/**
321 * drm_vma_node_revoke - Remove open-file from list of allowed users
322 * @node: Node to modify
323 * @tag: Tag of file to remove
324 *
325 * Decrement the ref-count of @tag in the list of allowed open-files on @node.
326 * If the ref-count drops to zero, remove @tag from the list. You must call
327 * this once for every drm_vma_node_allow() on @tag.
328 *
329 * This is locked against concurrent access internally.
330 *
331 * If @tag is not on the list, nothing is done.
332 */
333void drm_vma_node_revoke(struct drm_vma_offset_node *node,
334 struct drm_file *tag)
335{
336 struct drm_vma_offset_file *entry;
337 struct rb_node *iter;
338
339 write_lock(&node->vm_lock);
340
341 iter = node->vm_files.rb_node;
342 while (likely(iter)) {
343 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
344 if (tag == entry->vm_tag) {
345 if (!--entry->vm_count) {
346 rb_erase(&entry->vm_rb, &node->vm_files);
347 kfree(entry);
348 }
349 break;
350 } else if (tag > entry->vm_tag) {
351 iter = iter->rb_right;
352 } else {
353 iter = iter->rb_left;
354 }
355 }
356
357 write_unlock(&node->vm_lock);
358}
359EXPORT_SYMBOL(drm_vma_node_revoke);
360
361/**
362 * drm_vma_node_is_allowed - Check whether an open-file is granted access
363 * @node: Node to check
364 * @tag: Tag of file to remove
365 *
366 * Search the list in @node whether @tag is currently on the list of allowed
367 * open-files (see drm_vma_node_allow()).
368 *
369 * This is locked against concurrent access internally.
370 *
371 * RETURNS:
372 * true iff @filp is on the list
373 */
374bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
375 struct drm_file *tag)
376{
377 struct drm_vma_offset_file *entry;
378 struct rb_node *iter;
379
380 read_lock(&node->vm_lock);
381
382 iter = node->vm_files.rb_node;
383 while (likely(iter)) {
384 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
385 if (tag == entry->vm_tag)
386 break;
387 else if (tag > entry->vm_tag)
388 iter = iter->rb_right;
389 else
390 iter = iter->rb_left;
391 }
392
393 read_unlock(&node->vm_lock);
394
395 return iter;
396}
397EXPORT_SYMBOL(drm_vma_node_is_allowed);