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>
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:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
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.
26 #include <drm/drm_mm.h>
27 #include <drm/drm_vma_manager.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>
36 * DOC: vma offset manager
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.
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.
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.
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().
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.
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)
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.
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.
84 void drm_vma_offset_manager_init(struct drm_vma_offset_manager
*mgr
,
85 unsigned long page_offset
, unsigned long size
)
87 lockinit(&mgr
->vm_lock
, "drmvml", 0, LK_CANRECURSE
);
88 mgr
->vm_addr_space_rb
= RB_ROOT
;
89 drm_mm_init(&mgr
->vm_addr_space_mm
, page_offset
, size
);
91 EXPORT_SYMBOL(drm_vma_offset_manager_init
);
94 * drm_vma_offset_manager_destroy() - Destroy offset manager
95 * @mgr: Manager object
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.
102 * The manager must not be accessed after this function is called.
104 void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager
*mgr
)
106 /* take the lock to protect against buggy drivers */
107 lockmgr(&mgr
->vm_lock
, LK_EXCLUSIVE
);
108 drm_mm_takedown(&mgr
->vm_addr_space_mm
);
109 lockmgr(&mgr
->vm_lock
, LK_RELEASE
);
111 EXPORT_SYMBOL(drm_vma_offset_manager_destroy
);
114 * drm_vma_offset_lookup_locked() - Find node in offset space
115 * @mgr: Manager object
116 * @start: Start address for object (page-based)
117 * @pages: Size of object (page-based)
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).
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().
129 * drm_vma_offset_lock_lookup(mgr);
130 * node = drm_vma_offset_lookup_locked(mgr);
132 * kref_get_unless_zero(container_of(node, sth, entr));
133 * drm_vma_offset_unlock_lookup(mgr);
136 * Returns NULL if no suitable node can be found. Otherwise, the best match
137 * is returned. It's the caller's responsibility to make sure the node doesn't
138 * get destroyed before the caller can access it.
140 struct drm_vma_offset_node
*drm_vma_offset_lookup_locked(struct drm_vma_offset_manager
*mgr
,
144 struct drm_vma_offset_node
*node
, *best
;
145 struct rb_node
*iter
;
146 unsigned long offset
;
148 iter
= mgr
->vm_addr_space_rb
.rb_node
;
151 while (likely(iter
)) {
152 node
= rb_entry(iter
, struct drm_vma_offset_node
, vm_rb
);
153 offset
= node
->vm_node
.start
;
154 if (start
>= offset
) {
155 iter
= iter
->rb_right
;
160 iter
= iter
->rb_left
;
164 /* verify that the node spans the requested area */
166 offset
= best
->vm_node
.start
+ best
->vm_node
.size
;
167 if (offset
< start
+ pages
)
173 EXPORT_SYMBOL(drm_vma_offset_lookup_locked
);
175 /* internal helper to link @node into the rb-tree */
176 static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager
*mgr
,
177 struct drm_vma_offset_node
*node
)
179 struct rb_node
**iter
= &mgr
->vm_addr_space_rb
.rb_node
;
180 struct rb_node
*parent
= NULL
;
181 struct drm_vma_offset_node
*iter_node
;
183 while (likely(*iter
)) {
185 iter_node
= rb_entry(*iter
, struct drm_vma_offset_node
, vm_rb
);
187 if (node
->vm_node
.start
< iter_node
->vm_node
.start
)
188 iter
= &(*iter
)->rb_left
;
189 else if (node
->vm_node
.start
> iter_node
->vm_node
.start
)
190 iter
= &(*iter
)->rb_right
;
195 rb_link_node(&node
->vm_rb
, parent
, iter
);
196 rb_insert_color(&node
->vm_rb
, &mgr
->vm_addr_space_rb
);
200 * drm_vma_offset_add() - Add offset node to manager
201 * @mgr: Manager object
202 * @node: Node to be added
203 * @pages: Allocation size visible to user-space (in number of pages)
205 * Add a node to the offset-manager. If the node was already added, this does
206 * nothing and return 0. @pages is the size of the object given in number of
208 * After this call succeeds, you can access the offset of the node until it
211 * If this call fails, it is safe to retry the operation or call
212 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
215 * @pages is not required to be the same size as the underlying memory object
216 * that you want to map. It only limits the size that user-space can map into
217 * their address space.
220 * 0 on success, negative error code on failure.
222 int drm_vma_offset_add(struct drm_vma_offset_manager
*mgr
,
223 struct drm_vma_offset_node
*node
, unsigned long pages
)
227 lockmgr(&mgr
->vm_lock
, LK_EXCLUSIVE
);
229 if (drm_mm_node_allocated(&node
->vm_node
)) {
234 ret
= drm_mm_insert_node(&mgr
->vm_addr_space_mm
, &node
->vm_node
,
235 pages
, 0, DRM_MM_SEARCH_DEFAULT
);
239 _drm_vma_offset_add_rb(mgr
, node
);
242 lockmgr(&mgr
->vm_lock
, LK_RELEASE
);
245 EXPORT_SYMBOL(drm_vma_offset_add
);
248 * drm_vma_offset_remove() - Remove offset node from manager
249 * @mgr: Manager object
250 * @node: Node to be removed
252 * Remove a node from the offset manager. If the node wasn't added before, this
253 * does nothing. After this call returns, the offset and size will be 0 until a
254 * new offset is allocated via drm_vma_offset_add() again. Helper functions like
255 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
256 * offset is allocated.
258 void drm_vma_offset_remove(struct drm_vma_offset_manager
*mgr
,
259 struct drm_vma_offset_node
*node
)
261 lockmgr(&mgr
->vm_lock
, LK_EXCLUSIVE
);
263 if (drm_mm_node_allocated(&node
->vm_node
)) {
264 rb_erase(&node
->vm_rb
, &mgr
->vm_addr_space_rb
);
265 drm_mm_remove_node(&node
->vm_node
);
266 memset(&node
->vm_node
, 0, sizeof(node
->vm_node
));
269 lockmgr(&mgr
->vm_lock
, LK_RELEASE
);
271 EXPORT_SYMBOL(drm_vma_offset_remove
);
274 * drm_vma_node_allow - Add open-file to list of allowed users
275 * @node: Node to modify
276 * @filp: Open file to add
278 * Add @filp to the list of allowed open-files for this node. If @filp is
279 * already on this list, the ref-count is incremented.
281 * The list of allowed-users is preserved across drm_vma_offset_add() and
282 * drm_vma_offset_remove() calls. You may even call it if the node is currently
283 * not added to any offset-manager.
285 * You must remove all open-files the same number of times as you added them
286 * before destroying the node. Otherwise, you will leak memory.
288 * This is locked against concurrent access internally.
291 * 0 on success, negative error code on internal failure (out-of-mem)
293 int drm_vma_node_allow(struct drm_vma_offset_node
*node
, struct file
*filp
)
295 struct rb_node
**iter
;
296 struct rb_node
*parent
= NULL
;
297 struct drm_vma_offset_file
*new, *entry
;
300 /* Preallocate entry to avoid atomic allocations below. It is quite
301 * unlikely that an open-file is added twice to a single node so we
302 * don't optimize for this case. OOM is checked below only if the entry
303 * is actually used. */
304 new = kmalloc(sizeof(*entry
), M_DRM
, M_WAITOK
);
306 lockmgr(&node
->vm_lock
, LK_EXCLUSIVE
);
308 iter
= &node
->vm_files
.rb_node
;
310 while (likely(*iter
)) {
312 entry
= rb_entry(*iter
, struct drm_vma_offset_file
, vm_rb
);
314 if (filp
== entry
->vm_filp
) {
317 } else if (filp
> entry
->vm_filp
) {
318 iter
= &(*iter
)->rb_right
;
320 iter
= &(*iter
)->rb_left
;
331 rb_link_node(&new->vm_rb
, parent
, iter
);
332 rb_insert_color(&new->vm_rb
, &node
->vm_files
);
336 lockmgr(&node
->vm_lock
, LK_RELEASE
);
340 EXPORT_SYMBOL(drm_vma_node_allow
);
343 * drm_vma_node_revoke - Remove open-file from list of allowed users
344 * @node: Node to modify
345 * @filp: Open file to remove
347 * Decrement the ref-count of @filp in the list of allowed open-files on @node.
348 * If the ref-count drops to zero, remove @filp from the list. You must call
349 * this once for every drm_vma_node_allow() on @filp.
351 * This is locked against concurrent access internally.
353 * If @filp is not on the list, nothing is done.
355 void drm_vma_node_revoke(struct drm_vma_offset_node
*node
, struct file
*filp
)
357 struct drm_vma_offset_file
*entry
;
358 struct rb_node
*iter
;
360 lockmgr(&node
->vm_lock
, LK_EXCLUSIVE
);
362 iter
= node
->vm_files
.rb_node
;
363 while (likely(iter
)) {
364 entry
= rb_entry(iter
, struct drm_vma_offset_file
, vm_rb
);
365 if (filp
== entry
->vm_filp
) {
366 if (!--entry
->vm_count
) {
367 rb_erase(&entry
->vm_rb
, &node
->vm_files
);
371 } else if (filp
> entry
->vm_filp
) {
372 iter
= iter
->rb_right
;
374 iter
= iter
->rb_left
;
378 lockmgr(&node
->vm_lock
, LK_RELEASE
);
380 EXPORT_SYMBOL(drm_vma_node_revoke
);
383 * drm_vma_node_is_allowed - Check whether an open-file is granted access
384 * @node: Node to check
385 * @filp: Open-file to check for
387 * Search the list in @node whether @filp is currently on the list of allowed
388 * open-files (see drm_vma_node_allow()).
390 * This is locked against concurrent access internally.
393 * true iff @filp is on the list
395 bool drm_vma_node_is_allowed(struct drm_vma_offset_node
*node
,
398 struct drm_vma_offset_file
*entry
;
399 struct rb_node
*iter
;
401 lockmgr(&node
->vm_lock
, LK_EXCLUSIVE
);
403 iter
= node
->vm_files
.rb_node
;
404 while (likely(iter
)) {
405 entry
= rb_entry(iter
, struct drm_vma_offset_file
, vm_rb
);
406 if (filp
== entry
->vm_filp
)
408 else if (filp
> entry
->vm_filp
)
409 iter
= iter
->rb_right
;
411 iter
= iter
->rb_left
;
414 lockmgr(&node
->vm_lock
, LK_RELEASE
);
418 EXPORT_SYMBOL(drm_vma_node_is_allowed
);