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fe3078fa DH |
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> | |
88d7ebe5 | 28 | #include <linux/fs.h> |
fe3078fa DH |
29 | #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 | |
0661a336 | 53 | * no longer be linear. |
fe3078fa DH |
54 | * |
55 | * This offset manager works on page-based addresses. That is, every argument | |
56 | * and return code (with the exception of drm_vma_node_offset_addr()) is given | |
57 | * in number of pages, not number of bytes. That means, object sizes and offsets | |
58 | * must always be page-aligned (as usual). | |
59 | * If you want to get a valid byte-based user-space address for a given offset, | |
60 | * please see drm_vma_node_offset_addr(). | |
88d7ebe5 DH |
61 | * |
62 | * Additionally to offset management, the vma offset manager also handles access | |
63 | * management. For every open-file context that is allowed to access a given | |
64 | * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this | |
65 | * open-file with the offset of the node will fail with -EACCES. To revoke | |
66 | * access again, use drm_vma_node_revoke(). However, the caller is responsible | |
67 | * for destroying already existing mappings, if required. | |
fe3078fa DH |
68 | */ |
69 | ||
70 | /** | |
71 | * drm_vma_offset_manager_init - Initialize new offset-manager | |
72 | * @mgr: Manager object | |
73 | * @page_offset: Offset of available memory area (page-based) | |
74 | * @size: Size of available address space range (page-based) | |
75 | * | |
76 | * Initialize a new offset-manager. The offset and area size available for the | |
77 | * manager are given as @page_offset and @size. Both are interpreted as | |
78 | * page-numbers, not bytes. | |
79 | * | |
80 | * Adding/removing nodes from the manager is locked internally and protected | |
81 | * against concurrent access. However, node allocation and destruction is left | |
82 | * for the caller. While calling into the vma-manager, a given node must | |
83 | * always be guaranteed to be referenced. | |
84 | */ | |
85 | void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr, | |
86 | unsigned long page_offset, unsigned long size) | |
87 | { | |
88 | rwlock_init(&mgr->vm_lock); | |
fe3078fa DH |
89 | drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size); |
90 | } | |
91 | EXPORT_SYMBOL(drm_vma_offset_manager_init); | |
92 | ||
93 | /** | |
94 | * drm_vma_offset_manager_destroy() - Destroy offset manager | |
95 | * @mgr: Manager object | |
96 | * | |
97 | * Destroy an object manager which was previously created via | |
98 | * drm_vma_offset_manager_init(). The caller must remove all allocated nodes | |
99 | * before destroying the manager. Otherwise, drm_mm will refuse to free the | |
100 | * requested resources. | |
101 | * | |
102 | * The manager must not be accessed after this function is called. | |
103 | */ | |
104 | void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) | |
105 | { | |
106 | /* take the lock to protect against buggy drivers */ | |
107 | write_lock(&mgr->vm_lock); | |
108 | drm_mm_takedown(&mgr->vm_addr_space_mm); | |
109 | write_unlock(&mgr->vm_lock); | |
110 | } | |
111 | EXPORT_SYMBOL(drm_vma_offset_manager_destroy); | |
112 | ||
113 | /** | |
2225cfe4 | 114 | * drm_vma_offset_lookup_locked() - Find node in offset space |
fe3078fa DH |
115 | * @mgr: Manager object |
116 | * @start: Start address for object (page-based) | |
117 | * @pages: Size of object (page-based) | |
118 | * | |
119 | * Find a node given a start address and object size. This returns the _best_ | |
120 | * match for the given node. That is, @start may point somewhere into a valid | |
121 | * region and the given node will be returned, as long as the node spans the | |
122 | * whole requested area (given the size in number of pages as @pages). | |
123 | * | |
2225cfe4 DV |
124 | * Note that before lookup the vma offset manager lookup lock must be acquired |
125 | * with drm_vma_offset_lock_lookup(). See there for an example. This can then be | |
126 | * used to implement weakly referenced lookups using kref_get_unless_zero(). | |
fe3078fa | 127 | * |
2225cfe4 | 128 | * Example: |
da5335b8 DV |
129 | * |
130 | * :: | |
131 | * | |
2225cfe4 DV |
132 | * drm_vma_offset_lock_lookup(mgr); |
133 | * node = drm_vma_offset_lookup_locked(mgr); | |
134 | * if (node) | |
135 | * kref_get_unless_zero(container_of(node, sth, entr)); | |
136 | * drm_vma_offset_unlock_lookup(mgr); | |
fe3078fa DH |
137 | * |
138 | * RETURNS: | |
139 | * Returns NULL if no suitable node can be found. Otherwise, the best match | |
2225cfe4 DV |
140 | * is returned. It's the caller's responsibility to make sure the node doesn't |
141 | * get destroyed before the caller can access it. | |
fe3078fa DH |
142 | */ |
143 | struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, | |
144 | unsigned long start, | |
145 | unsigned long pages) | |
146 | { | |
db2395ec | 147 | struct drm_mm_node *node, *best; |
fe3078fa DH |
148 | struct rb_node *iter; |
149 | unsigned long offset; | |
150 | ||
db2395ec | 151 | iter = mgr->vm_addr_space_mm.interval_tree.rb_node; |
fe3078fa DH |
152 | best = NULL; |
153 | ||
154 | while (likely(iter)) { | |
db2395ec CW |
155 | node = rb_entry(iter, struct drm_mm_node, rb); |
156 | offset = node->start; | |
fe3078fa DH |
157 | if (start >= offset) { |
158 | iter = iter->rb_right; | |
159 | best = node; | |
160 | if (start == offset) | |
161 | break; | |
162 | } else { | |
163 | iter = iter->rb_left; | |
164 | } | |
165 | } | |
166 | ||
167 | /* verify that the node spans the requested area */ | |
168 | if (best) { | |
db2395ec | 169 | offset = best->start + best->size; |
fe3078fa DH |
170 | if (offset < start + pages) |
171 | best = NULL; | |
172 | } | |
173 | ||
db2395ec CW |
174 | if (!best) |
175 | return NULL; | |
fe3078fa | 176 | |
db2395ec | 177 | return container_of(best, struct drm_vma_offset_node, vm_node); |
fe3078fa | 178 | } |
db2395ec | 179 | EXPORT_SYMBOL(drm_vma_offset_lookup_locked); |
fe3078fa DH |
180 | |
181 | /** | |
182 | * drm_vma_offset_add() - Add offset node to manager | |
183 | * @mgr: Manager object | |
184 | * @node: Node to be added | |
185 | * @pages: Allocation size visible to user-space (in number of pages) | |
186 | * | |
187 | * Add a node to the offset-manager. If the node was already added, this does | |
188 | * nothing and return 0. @pages is the size of the object given in number of | |
189 | * pages. | |
190 | * After this call succeeds, you can access the offset of the node until it | |
191 | * is removed again. | |
192 | * | |
193 | * If this call fails, it is safe to retry the operation or call | |
194 | * drm_vma_offset_remove(), anyway. However, no cleanup is required in that | |
195 | * case. | |
196 | * | |
197 | * @pages is not required to be the same size as the underlying memory object | |
198 | * that you want to map. It only limits the size that user-space can map into | |
199 | * their address space. | |
200 | * | |
201 | * RETURNS: | |
202 | * 0 on success, negative error code on failure. | |
203 | */ | |
204 | int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, | |
205 | struct drm_vma_offset_node *node, unsigned long pages) | |
206 | { | |
207 | int ret; | |
208 | ||
209 | write_lock(&mgr->vm_lock); | |
210 | ||
211 | if (drm_mm_node_allocated(&node->vm_node)) { | |
212 | ret = 0; | |
213 | goto out_unlock; | |
214 | } | |
215 | ||
31e5d7c6 DH |
216 | ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, |
217 | pages, 0, DRM_MM_SEARCH_DEFAULT); | |
fe3078fa DH |
218 | if (ret) |
219 | goto out_unlock; | |
220 | ||
fe3078fa DH |
221 | out_unlock: |
222 | write_unlock(&mgr->vm_lock); | |
223 | return ret; | |
224 | } | |
225 | EXPORT_SYMBOL(drm_vma_offset_add); | |
226 | ||
227 | /** | |
228 | * drm_vma_offset_remove() - Remove offset node from manager | |
229 | * @mgr: Manager object | |
230 | * @node: Node to be removed | |
231 | * | |
232 | * Remove a node from the offset manager. If the node wasn't added before, this | |
233 | * does nothing. After this call returns, the offset and size will be 0 until a | |
234 | * new offset is allocated via drm_vma_offset_add() again. Helper functions like | |
235 | * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no | |
236 | * offset is allocated. | |
237 | */ | |
238 | void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, | |
239 | struct drm_vma_offset_node *node) | |
240 | { | |
241 | write_lock(&mgr->vm_lock); | |
242 | ||
243 | if (drm_mm_node_allocated(&node->vm_node)) { | |
fe3078fa DH |
244 | drm_mm_remove_node(&node->vm_node); |
245 | memset(&node->vm_node, 0, sizeof(node->vm_node)); | |
246 | } | |
247 | ||
248 | write_unlock(&mgr->vm_lock); | |
249 | } | |
250 | EXPORT_SYMBOL(drm_vma_offset_remove); | |
88d7ebe5 DH |
251 | |
252 | /** | |
253 | * drm_vma_node_allow - Add open-file to list of allowed users | |
254 | * @node: Node to modify | |
255 | * @filp: Open file to add | |
256 | * | |
257 | * Add @filp to the list of allowed open-files for this node. If @filp is | |
258 | * already on this list, the ref-count is incremented. | |
259 | * | |
260 | * The list of allowed-users is preserved across drm_vma_offset_add() and | |
261 | * drm_vma_offset_remove() calls. You may even call it if the node is currently | |
262 | * not added to any offset-manager. | |
263 | * | |
264 | * You must remove all open-files the same number of times as you added them | |
265 | * before destroying the node. Otherwise, you will leak memory. | |
266 | * | |
267 | * This is locked against concurrent access internally. | |
268 | * | |
269 | * RETURNS: | |
270 | * 0 on success, negative error code on internal failure (out-of-mem) | |
271 | */ | |
272 | int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp) | |
273 | { | |
274 | struct rb_node **iter; | |
275 | struct rb_node *parent = NULL; | |
276 | struct drm_vma_offset_file *new, *entry; | |
277 | int ret = 0; | |
278 | ||
279 | /* Preallocate entry to avoid atomic allocations below. It is quite | |
280 | * unlikely that an open-file is added twice to a single node so we | |
281 | * don't optimize for this case. OOM is checked below only if the entry | |
282 | * is actually used. */ | |
283 | new = kmalloc(sizeof(*entry), GFP_KERNEL); | |
284 | ||
285 | write_lock(&node->vm_lock); | |
286 | ||
287 | iter = &node->vm_files.rb_node; | |
288 | ||
289 | while (likely(*iter)) { | |
290 | parent = *iter; | |
291 | entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb); | |
292 | ||
293 | if (filp == entry->vm_filp) { | |
294 | entry->vm_count++; | |
295 | goto unlock; | |
296 | } else if (filp > entry->vm_filp) { | |
297 | iter = &(*iter)->rb_right; | |
298 | } else { | |
299 | iter = &(*iter)->rb_left; | |
300 | } | |
301 | } | |
302 | ||
303 | if (!new) { | |
304 | ret = -ENOMEM; | |
305 | goto unlock; | |
306 | } | |
307 | ||
308 | new->vm_filp = filp; | |
309 | new->vm_count = 1; | |
310 | rb_link_node(&new->vm_rb, parent, iter); | |
311 | rb_insert_color(&new->vm_rb, &node->vm_files); | |
312 | new = NULL; | |
313 | ||
314 | unlock: | |
315 | write_unlock(&node->vm_lock); | |
316 | kfree(new); | |
317 | return ret; | |
318 | } | |
319 | EXPORT_SYMBOL(drm_vma_node_allow); | |
320 | ||
321 | /** | |
322 | * drm_vma_node_revoke - Remove open-file from list of allowed users | |
323 | * @node: Node to modify | |
324 | * @filp: Open file to remove | |
325 | * | |
326 | * Decrement the ref-count of @filp in the list of allowed open-files on @node. | |
327 | * If the ref-count drops to zero, remove @filp from the list. You must call | |
328 | * this once for every drm_vma_node_allow() on @filp. | |
329 | * | |
330 | * This is locked against concurrent access internally. | |
331 | * | |
332 | * If @filp is not on the list, nothing is done. | |
333 | */ | |
334 | void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp) | |
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 (filp == entry->vm_filp) { | |
345 | if (!--entry->vm_count) { | |
346 | rb_erase(&entry->vm_rb, &node->vm_files); | |
347 | kfree(entry); | |
348 | } | |
349 | break; | |
350 | } else if (filp > entry->vm_filp) { | |
351 | iter = iter->rb_right; | |
352 | } else { | |
353 | iter = iter->rb_left; | |
354 | } | |
355 | } | |
356 | ||
357 | write_unlock(&node->vm_lock); | |
358 | } | |
359 | EXPORT_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 | * @filp: Open-file to check for | |
365 | * | |
366 | * Search the list in @node whether @filp 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 | */ | |
374 | bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node, | |
375 | struct file *filp) | |
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 (filp == entry->vm_filp) | |
386 | break; | |
387 | else if (filp > entry->vm_filp) | |
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 | } | |
397 | EXPORT_SYMBOL(drm_vma_node_is_allowed); |