summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/drm_vma_manager.c
blob: 28f1226576f8c16cb953f48c0e2eafdebff35a0d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
/*
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * Copyright (c) 2012 David Airlie <airlied@linux.ie>
 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include <drm/drmP.h>
#include <drm/drm_mm.h>
#include <drm/drm_vma_manager.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>

/**
 * DOC: vma offset manager
 *
 * The vma-manager is responsible to map arbitrary driver-dependent memory
 * regions into the linear user address-space. It provides offsets to the
 * caller which can then be used on the address_space of the drm-device. It
 * takes care to not overlap regions, size them appropriately and to not
 * confuse mm-core by inconsistent fake vm_pgoff fields.
 * Drivers shouldn't use this for object placement in VMEM. This manager should
 * only be used to manage mappings into linear user-space VMs.
 *
 * We use drm_mm as backend to manage object allocations. But it is highly
 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to
 * speed up offset lookups.
 *
 * You must not use multiple offset managers on a single address_space.
 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will
 * no longer be linear.
 *
 * This offset manager works on page-based addresses. That is, every argument
 * and return code (with the exception of drm_vma_node_offset_addr()) is given
 * in number of pages, not number of bytes. That means, object sizes and offsets
 * must always be page-aligned (as usual).
 * If you want to get a valid byte-based user-space address for a given offset,
 * please see drm_vma_node_offset_addr().
 *
 * Additionally to offset management, the vma offset manager also handles access
 * management. For every open-file context that is allowed to access a given
 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this
 * open-file with the offset of the node will fail with -EACCES. To revoke
 * access again, use drm_vma_node_revoke(). However, the caller is responsible
 * for destroying already existing mappings, if required.
 */

/**
 * drm_vma_offset_manager_init - Initialize new offset-manager
 * @mgr: Manager object
 * @page_offset: Offset of available memory area (page-based)
 * @size: Size of available address space range (page-based)
 *
 * Initialize a new offset-manager. The offset and area size available for the
 * manager are given as @page_offset and @size. Both are interpreted as
 * page-numbers, not bytes.
 *
 * Adding/removing nodes from the manager is locked internally and protected
 * against concurrent access. However, node allocation and destruction is left
 * for the caller. While calling into the vma-manager, a given node must
 * always be guaranteed to be referenced.
 */
void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
				 unsigned long page_offset, unsigned long size)
{
	rwlock_init(&mgr->vm_lock);
	drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);
}
EXPORT_SYMBOL(drm_vma_offset_manager_init);

/**
 * drm_vma_offset_manager_destroy() - Destroy offset manager
 * @mgr: Manager object
 *
 * Destroy an object manager which was previously created via
 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes
 * before destroying the manager. Otherwise, drm_mm will refuse to free the
 * requested resources.
 *
 * The manager must not be accessed after this function is called.
 */
void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
{
	/* take the lock to protect against buggy drivers */
	write_lock(&mgr->vm_lock);
	drm_mm_takedown(&mgr->vm_addr_space_mm);
	write_unlock(&mgr->vm_lock);
}
EXPORT_SYMBOL(drm_vma_offset_manager_destroy);

/**
 * drm_vma_offset_lookup_locked() - Find node in offset space
 * @mgr: Manager object
 * @start: Start address for object (page-based)
 * @pages: Size of object (page-based)
 *
 * Find a node given a start address and object size. This returns the _best_
 * match for the given node. That is, @start may point somewhere into a valid
 * region and the given node will be returned, as long as the node spans the
 * whole requested area (given the size in number of pages as @pages).
 *
 * Note that before lookup the vma offset manager lookup lock must be acquired
 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be
 * used to implement weakly referenced lookups using kref_get_unless_zero().
 *
 * Example:
 *
 * ::
 *
 *     drm_vma_offset_lock_lookup(mgr);
 *     node = drm_vma_offset_lookup_locked(mgr);
 *     if (node)
 *         kref_get_unless_zero(container_of(node, sth, entr));
 *     drm_vma_offset_unlock_lookup(mgr);
 *
 * RETURNS:
 * Returns NULL if no suitable node can be found. Otherwise, the best match
 * is returned. It's the caller's responsibility to make sure the node doesn't
 * get destroyed before the caller can access it.
 */
struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
							 unsigned long start,
							 unsigned long pages)
{
	struct drm_mm_node *node, *best;
	struct rb_node *iter;
	unsigned long offset;

	iter = mgr->vm_addr_space_mm.interval_tree.rb_root.rb_node;
	best = NULL;

	while (likely(iter)) {
		node = rb_entry(iter, struct drm_mm_node, rb);
		offset = node->start;
		if (start >= offset) {
			iter = iter->rb_right;
			best = node;
			if (start == offset)
				break;
		} else {
			iter = iter->rb_left;
		}
	}

	/* verify that the node spans the requested area */
	if (best) {
		offset = best->start + best->size;
		if (offset < start + pages)
			best = NULL;
	}

	if (!best)
		return NULL;

	return container_of(best, struct drm_vma_offset_node, vm_node);
}
EXPORT_SYMBOL(drm_vma_offset_lookup_locked);

/**
 * drm_vma_offset_add() - Add offset node to manager
 * @mgr: Manager object
 * @node: Node to be added
 * @pages: Allocation size visible to user-space (in number of pages)
 *
 * Add a node to the offset-manager. If the node was already added, this does
 * nothing and return 0. @pages is the size of the object given in number of
 * pages.
 * After this call succeeds, you can access the offset of the node until it
 * is removed again.
 *
 * If this call fails, it is safe to retry the operation or call
 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
 * case.
 *
 * @pages is not required to be the same size as the underlying memory object
 * that you want to map. It only limits the size that user-space can map into
 * their address space.
 *
 * RETURNS:
 * 0 on success, negative error code on failure.
 */
int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
		       struct drm_vma_offset_node *node, unsigned long pages)
{
	int ret;

	write_lock(&mgr->vm_lock);

	if (drm_mm_node_allocated(&node->vm_node)) {
		ret = 0;
		goto out_unlock;
	}

	ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, pages);
	if (ret)
		goto out_unlock;

out_unlock:
	write_unlock(&mgr->vm_lock);
	return ret;
}
EXPORT_SYMBOL(drm_vma_offset_add);

/**
 * drm_vma_offset_remove() - Remove offset node from manager
 * @mgr: Manager object
 * @node: Node to be removed
 *
 * Remove a node from the offset manager. If the node wasn't added before, this
 * does nothing. After this call returns, the offset and size will be 0 until a
 * new offset is allocated via drm_vma_offset_add() again. Helper functions like
 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
 * offset is allocated.
 */
void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
			   struct drm_vma_offset_node *node)
{
	write_lock(&mgr->vm_lock);

	if (drm_mm_node_allocated(&node->vm_node)) {
		drm_mm_remove_node(&node->vm_node);
		memset(&node->vm_node, 0, sizeof(node->vm_node));
	}

	write_unlock(&mgr->vm_lock);
}
EXPORT_SYMBOL(drm_vma_offset_remove);

/**
 * drm_vma_node_allow - Add open-file to list of allowed users
 * @node: Node to modify
 * @tag: Tag of file to remove
 *
 * Add @tag to the list of allowed open-files for this node. If @tag is
 * already on this list, the ref-count is incremented.
 *
 * The list of allowed-users is preserved across drm_vma_offset_add() and
 * drm_vma_offset_remove() calls. You may even call it if the node is currently
 * not added to any offset-manager.
 *
 * You must remove all open-files the same number of times as you added them
 * before destroying the node. Otherwise, you will leak memory.
 *
 * This is locked against concurrent access internally.
 *
 * RETURNS:
 * 0 on success, negative error code on internal failure (out-of-mem)
 */
int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
{
	struct rb_node **iter;
	struct rb_node *parent = NULL;
	struct drm_vma_offset_file *new, *entry;
	int ret = 0;

	/* Preallocate entry to avoid atomic allocations below. It is quite
	 * unlikely that an open-file is added twice to a single node so we
	 * don't optimize for this case. OOM is checked below only if the entry
	 * is actually used. */
	new = kmalloc(sizeof(*entry), GFP_KERNEL);

	write_lock(&node->vm_lock);

	iter = &node->vm_files.rb_node;

	while (likely(*iter)) {
		parent = *iter;
		entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);

		if (tag == entry->vm_tag) {
			entry->vm_count++;
			goto unlock;
		} else if (tag > entry->vm_tag) {
			iter = &(*iter)->rb_right;
		} else {
			iter = &(*iter)->rb_left;
		}
	}

	if (!new) {
		ret = -ENOMEM;
		goto unlock;
	}

	new->vm_tag = tag;
	new->vm_count = 1;
	rb_link_node(&new->vm_rb, parent, iter);
	rb_insert_color(&new->vm_rb, &node->vm_files);
	new = NULL;

unlock:
	write_unlock(&node->vm_lock);
	kfree(new);
	return ret;
}
EXPORT_SYMBOL(drm_vma_node_allow);

/**
 * drm_vma_node_revoke - Remove open-file from list of allowed users
 * @node: Node to modify
 * @tag: Tag of file to remove
 *
 * Decrement the ref-count of @tag in the list of allowed open-files on @node.
 * If the ref-count drops to zero, remove @tag from the list. You must call
 * this once for every drm_vma_node_allow() on @tag.
 *
 * This is locked against concurrent access internally.
 *
 * If @tag is not on the list, nothing is done.
 */
void drm_vma_node_revoke(struct drm_vma_offset_node *node,
			 struct drm_file *tag)
{
	struct drm_vma_offset_file *entry;
	struct rb_node *iter;

	write_lock(&node->vm_lock);

	iter = node->vm_files.rb_node;
	while (likely(iter)) {
		entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
		if (tag == entry->vm_tag) {
			if (!--entry->vm_count) {
				rb_erase(&entry->vm_rb, &node->vm_files);
				kfree(entry);
			}
			break;
		} else if (tag > entry->vm_tag) {
			iter = iter->rb_right;
		} else {
			iter = iter->rb_left;
		}
	}

	write_unlock(&node->vm_lock);
}
EXPORT_SYMBOL(drm_vma_node_revoke);

/**
 * drm_vma_node_is_allowed - Check whether an open-file is granted access
 * @node: Node to check
 * @tag: Tag of file to remove
 *
 * Search the list in @node whether @tag is currently on the list of allowed
 * open-files (see drm_vma_node_allow()).
 *
 * This is locked against concurrent access internally.
 *
 * RETURNS:
 * true iff @filp is on the list
 */
bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
			     struct drm_file *tag)
{
	struct drm_vma_offset_file *entry;
	struct rb_node *iter;

	read_lock(&node->vm_lock);

	iter = node->vm_files.rb_node;
	while (likely(iter)) {
		entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
		if (tag == entry->vm_tag)
			break;
		else if (tag > entry->vm_tag)
			iter = iter->rb_right;
		else
			iter = iter->rb_left;
	}

	read_unlock(&node->vm_lock);

	return iter;
}
EXPORT_SYMBOL(drm_vma_node_is_allowed);