blob: 63b471205072fb5bf2c11b2273efe1b9a7e63b5d [file] [log] [blame]
David Herrmannfe3078f2013-07-24 21:06:15 +02001/*
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>
David Herrmann88d7ebe2013-08-25 18:28:57 +020028#include <linux/fs.h>
David Herrmannfe3078f2013-07-24 21:06:15 +020029#include <linux/mm.h>
30#include <linux/module.h>
31#include <linux/rbtree.h>
32#include <linux/slab.h>
33#include <linux/spinlock.h>
34#include <linux/types.h>
35
36/**
37 * DOC: vma offset manager
38 *
39 * The vma-manager is responsible to map arbitrary driver-dependent memory
40 * regions into the linear user address-space. It provides offsets to the
41 * caller which can then be used on the address_space of the drm-device. It
42 * takes care to not overlap regions, size them appropriately and to not
43 * confuse mm-core by inconsistent fake vm_pgoff fields.
44 * Drivers shouldn't use this for object placement in VMEM. This manager should
45 * only be used to manage mappings into linear user-space VMs.
46 *
47 * We use drm_mm as backend to manage object allocations. But it is highly
48 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to
49 * speed up offset lookups.
50 *
51 * You must not use multiple offset managers on a single address_space.
52 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will
53 * no longer be linear. Please use VM_NONLINEAR in that case and implement your
54 * own offset managers.
55 *
56 * This offset manager works on page-based addresses. That is, every argument
57 * and return code (with the exception of drm_vma_node_offset_addr()) is given
58 * in number of pages, not number of bytes. That means, object sizes and offsets
59 * must always be page-aligned (as usual).
60 * If you want to get a valid byte-based user-space address for a given offset,
61 * please see drm_vma_node_offset_addr().
David Herrmann88d7ebe2013-08-25 18:28:57 +020062 *
63 * Additionally to offset management, the vma offset manager also handles access
64 * management. For every open-file context that is allowed to access a given
65 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this
66 * open-file with the offset of the node will fail with -EACCES. To revoke
67 * access again, use drm_vma_node_revoke(). However, the caller is responsible
68 * for destroying already existing mappings, if required.
David Herrmannfe3078f2013-07-24 21:06:15 +020069 */
70
71/**
72 * drm_vma_offset_manager_init - Initialize new offset-manager
73 * @mgr: Manager object
74 * @page_offset: Offset of available memory area (page-based)
75 * @size: Size of available address space range (page-based)
76 *
77 * Initialize a new offset-manager. The offset and area size available for the
78 * manager are given as @page_offset and @size. Both are interpreted as
79 * page-numbers, not bytes.
80 *
81 * Adding/removing nodes from the manager is locked internally and protected
82 * against concurrent access. However, node allocation and destruction is left
83 * for the caller. While calling into the vma-manager, a given node must
84 * always be guaranteed to be referenced.
85 */
86void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
87 unsigned long page_offset, unsigned long size)
88{
89 rwlock_init(&mgr->vm_lock);
90 mgr->vm_addr_space_rb = RB_ROOT;
91 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);
92}
93EXPORT_SYMBOL(drm_vma_offset_manager_init);
94
95/**
96 * drm_vma_offset_manager_destroy() - Destroy offset manager
97 * @mgr: Manager object
98 *
99 * Destroy an object manager which was previously created via
100 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes
101 * before destroying the manager. Otherwise, drm_mm will refuse to free the
102 * requested resources.
103 *
104 * The manager must not be accessed after this function is called.
105 */
106void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
107{
108 /* take the lock to protect against buggy drivers */
109 write_lock(&mgr->vm_lock);
110 drm_mm_takedown(&mgr->vm_addr_space_mm);
111 write_unlock(&mgr->vm_lock);
112}
113EXPORT_SYMBOL(drm_vma_offset_manager_destroy);
114
115/**
116 * drm_vma_offset_lookup() - Find node in offset space
117 * @mgr: Manager object
118 * @start: Start address for object (page-based)
119 * @pages: Size of object (page-based)
120 *
121 * Find a node given a start address and object size. This returns the _best_
122 * match for the given node. That is, @start may point somewhere into a valid
123 * region and the given node will be returned, as long as the node spans the
124 * whole requested area (given the size in number of pages as @pages).
125 *
126 * RETURNS:
127 * Returns NULL if no suitable node can be found. Otherwise, the best match
128 * is returned. It's the caller's responsibility to make sure the node doesn't
129 * get destroyed before the caller can access it.
130 */
131struct drm_vma_offset_node *drm_vma_offset_lookup(struct drm_vma_offset_manager *mgr,
132 unsigned long start,
133 unsigned long pages)
134{
135 struct drm_vma_offset_node *node;
136
137 read_lock(&mgr->vm_lock);
138 node = drm_vma_offset_lookup_locked(mgr, start, pages);
139 read_unlock(&mgr->vm_lock);
140
141 return node;
142}
143EXPORT_SYMBOL(drm_vma_offset_lookup);
144
145/**
146 * drm_vma_offset_lookup_locked() - Find node in offset space
147 * @mgr: Manager object
148 * @start: Start address for object (page-based)
149 * @pages: Size of object (page-based)
150 *
151 * Same as drm_vma_offset_lookup() but requires the caller to lock offset lookup
152 * manually. See drm_vma_offset_lock_lookup() for an example.
153 *
154 * RETURNS:
155 * Returns NULL if no suitable node can be found. Otherwise, the best match
156 * is returned.
157 */
158struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
159 unsigned long start,
160 unsigned long pages)
161{
162 struct drm_vma_offset_node *node, *best;
163 struct rb_node *iter;
164 unsigned long offset;
165
166 iter = mgr->vm_addr_space_rb.rb_node;
167 best = NULL;
168
169 while (likely(iter)) {
170 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb);
171 offset = node->vm_node.start;
172 if (start >= offset) {
173 iter = iter->rb_right;
174 best = node;
175 if (start == offset)
176 break;
177 } else {
178 iter = iter->rb_left;
179 }
180 }
181
182 /* verify that the node spans the requested area */
183 if (best) {
184 offset = best->vm_node.start + best->vm_node.size;
185 if (offset < start + pages)
186 best = NULL;
187 }
188
189 return best;
190}
191EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
192
193/* internal helper to link @node into the rb-tree */
194static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr,
195 struct drm_vma_offset_node *node)
196{
197 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node;
198 struct rb_node *parent = NULL;
199 struct drm_vma_offset_node *iter_node;
200
201 while (likely(*iter)) {
202 parent = *iter;
203 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb);
204
205 if (node->vm_node.start < iter_node->vm_node.start)
206 iter = &(*iter)->rb_left;
207 else if (node->vm_node.start > iter_node->vm_node.start)
208 iter = &(*iter)->rb_right;
209 else
210 BUG();
211 }
212
213 rb_link_node(&node->vm_rb, parent, iter);
214 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb);
215}
216
217/**
218 * drm_vma_offset_add() - Add offset node to manager
219 * @mgr: Manager object
220 * @node: Node to be added
221 * @pages: Allocation size visible to user-space (in number of pages)
222 *
223 * Add a node to the offset-manager. If the node was already added, this does
224 * nothing and return 0. @pages is the size of the object given in number of
225 * pages.
226 * After this call succeeds, you can access the offset of the node until it
227 * is removed again.
228 *
229 * If this call fails, it is safe to retry the operation or call
230 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
231 * case.
232 *
233 * @pages is not required to be the same size as the underlying memory object
234 * that you want to map. It only limits the size that user-space can map into
235 * their address space.
236 *
237 * RETURNS:
238 * 0 on success, negative error code on failure.
239 */
240int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
241 struct drm_vma_offset_node *node, unsigned long pages)
242{
243 int ret;
244
245 write_lock(&mgr->vm_lock);
246
247 if (drm_mm_node_allocated(&node->vm_node)) {
248 ret = 0;
249 goto out_unlock;
250 }
251
David Herrmann31e5d7c2013-07-27 13:36:27 +0200252 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node,
253 pages, 0, DRM_MM_SEARCH_DEFAULT);
David Herrmannfe3078f2013-07-24 21:06:15 +0200254 if (ret)
255 goto out_unlock;
256
257 _drm_vma_offset_add_rb(mgr, node);
258
259out_unlock:
260 write_unlock(&mgr->vm_lock);
261 return ret;
262}
263EXPORT_SYMBOL(drm_vma_offset_add);
264
265/**
266 * drm_vma_offset_remove() - Remove offset node from manager
267 * @mgr: Manager object
268 * @node: Node to be removed
269 *
270 * Remove a node from the offset manager. If the node wasn't added before, this
271 * does nothing. After this call returns, the offset and size will be 0 until a
272 * new offset is allocated via drm_vma_offset_add() again. Helper functions like
273 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
274 * offset is allocated.
275 */
276void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
277 struct drm_vma_offset_node *node)
278{
279 write_lock(&mgr->vm_lock);
280
281 if (drm_mm_node_allocated(&node->vm_node)) {
282 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb);
283 drm_mm_remove_node(&node->vm_node);
284 memset(&node->vm_node, 0, sizeof(node->vm_node));
285 }
286
287 write_unlock(&mgr->vm_lock);
288}
289EXPORT_SYMBOL(drm_vma_offset_remove);
David Herrmann88d7ebe2013-08-25 18:28:57 +0200290
291/**
292 * drm_vma_node_allow - Add open-file to list of allowed users
293 * @node: Node to modify
294 * @filp: Open file to add
295 *
296 * Add @filp to the list of allowed open-files for this node. If @filp is
297 * already on this list, the ref-count is incremented.
298 *
299 * The list of allowed-users is preserved across drm_vma_offset_add() and
300 * drm_vma_offset_remove() calls. You may even call it if the node is currently
301 * not added to any offset-manager.
302 *
303 * You must remove all open-files the same number of times as you added them
304 * before destroying the node. Otherwise, you will leak memory.
305 *
306 * This is locked against concurrent access internally.
307 *
308 * RETURNS:
309 * 0 on success, negative error code on internal failure (out-of-mem)
310 */
311int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp)
312{
313 struct rb_node **iter;
314 struct rb_node *parent = NULL;
315 struct drm_vma_offset_file *new, *entry;
316 int ret = 0;
317
318 /* Preallocate entry to avoid atomic allocations below. It is quite
319 * unlikely that an open-file is added twice to a single node so we
320 * don't optimize for this case. OOM is checked below only if the entry
321 * is actually used. */
322 new = kmalloc(sizeof(*entry), GFP_KERNEL);
323
324 write_lock(&node->vm_lock);
325
326 iter = &node->vm_files.rb_node;
327
328 while (likely(*iter)) {
329 parent = *iter;
330 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);
331
332 if (filp == entry->vm_filp) {
333 entry->vm_count++;
334 goto unlock;
335 } else if (filp > entry->vm_filp) {
336 iter = &(*iter)->rb_right;
337 } else {
338 iter = &(*iter)->rb_left;
339 }
340 }
341
342 if (!new) {
343 ret = -ENOMEM;
344 goto unlock;
345 }
346
347 new->vm_filp = filp;
348 new->vm_count = 1;
349 rb_link_node(&new->vm_rb, parent, iter);
350 rb_insert_color(&new->vm_rb, &node->vm_files);
351 new = NULL;
352
353unlock:
354 write_unlock(&node->vm_lock);
355 kfree(new);
356 return ret;
357}
358EXPORT_SYMBOL(drm_vma_node_allow);
359
360/**
361 * drm_vma_node_revoke - Remove open-file from list of allowed users
362 * @node: Node to modify
363 * @filp: Open file to remove
364 *
365 * Decrement the ref-count of @filp in the list of allowed open-files on @node.
366 * If the ref-count drops to zero, remove @filp from the list. You must call
367 * this once for every drm_vma_node_allow() on @filp.
368 *
369 * This is locked against concurrent access internally.
370 *
371 * If @filp is not on the list, nothing is done.
372 */
373void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp)
374{
375 struct drm_vma_offset_file *entry;
376 struct rb_node *iter;
377
378 write_lock(&node->vm_lock);
379
380 iter = node->vm_files.rb_node;
381 while (likely(iter)) {
382 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
383 if (filp == entry->vm_filp) {
384 if (!--entry->vm_count) {
385 rb_erase(&entry->vm_rb, &node->vm_files);
386 kfree(entry);
387 }
388 break;
389 } else if (filp > entry->vm_filp) {
390 iter = iter->rb_right;
391 } else {
392 iter = iter->rb_left;
393 }
394 }
395
396 write_unlock(&node->vm_lock);
397}
398EXPORT_SYMBOL(drm_vma_node_revoke);
399
400/**
401 * drm_vma_node_is_allowed - Check whether an open-file is granted access
402 * @node: Node to check
403 * @filp: Open-file to check for
404 *
405 * Search the list in @node whether @filp is currently on the list of allowed
406 * open-files (see drm_vma_node_allow()).
407 *
408 * This is locked against concurrent access internally.
409 *
410 * RETURNS:
411 * true iff @filp is on the list
412 */
413bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
414 struct file *filp)
415{
416 struct drm_vma_offset_file *entry;
417 struct rb_node *iter;
418
419 read_lock(&node->vm_lock);
420
421 iter = node->vm_files.rb_node;
422 while (likely(iter)) {
423 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
424 if (filp == entry->vm_filp)
425 break;
426 else if (filp > entry->vm_filp)
427 iter = iter->rb_right;
428 else
429 iter = iter->rb_left;
430 }
431
432 read_unlock(&node->vm_lock);
433
434 return iter;
435}
436EXPORT_SYMBOL(drm_vma_node_is_allowed);