1 #ifndef __DRM_VMA_MANAGER_H__
2 #define __DRM_VMA_MANAGER_H__
3 
4 /*
5  * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>
6  *
7  * Permission is hereby granted, free of charge, to any person obtaining a
8  * copy of this software and associated documentation files (the "Software"),
9  * to deal in the Software without restriction, including without limitation
10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11  * and/or sell copies of the Software, and to permit persons to whom the
12  * Software is furnished to do so, subject to the following conditions:
13  *
14  * The above copyright notice and this permission notice shall be included in
15  * all copies or substantial portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
20  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
23  * OTHER DEALINGS IN THE SOFTWARE.
24  */
25 
26 #include <drm/drm_mm.h>
27 #include <linux/mm.h>
28 #include <linux/rbtree.h>
29 #include <linux/spinlock.h>
30 #include <linux/types.h>
31 
32 /* We make up offsets for buffer objects so we can recognize them at
33  * mmap time. pgoff in mmap is an unsigned long, so we need to make sure
34  * that the faked up offset will fit
35  */
36 #if BITS_PER_LONG == 64
37 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
38 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 256)
39 #else
40 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFUL >> PAGE_SHIFT) + 1)
41 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFUL >> PAGE_SHIFT) * 16)
42 #endif
43 
44 struct drm_file;
45 
46 struct drm_vma_offset_file {
47 	struct rb_node vm_rb;
48 	struct drm_file *vm_tag;
49 	unsigned long vm_count;
50 };
51 
52 struct drm_vma_offset_node {
53 	rwlock_t vm_lock;
54 	struct drm_mm_node vm_node;
55 	struct rb_root vm_files;
56 	void *driver_private;
57 };
58 
59 struct drm_vma_offset_manager {
60 	rwlock_t vm_lock;
61 	struct drm_mm vm_addr_space_mm;
62 };
63 
64 void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
65 				 unsigned long page_offset, unsigned long size);
66 void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr);
67 
68 struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
69 							   unsigned long start,
70 							   unsigned long pages);
71 int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
72 		       struct drm_vma_offset_node *node, unsigned long pages);
73 void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
74 			   struct drm_vma_offset_node *node);
75 
76 int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag);
77 void drm_vma_node_revoke(struct drm_vma_offset_node *node,
78 			 struct drm_file *tag);
79 bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
80 			     struct drm_file *tag);
81 
82 /**
83  * drm_vma_offset_exact_lookup_locked() - Look up node by exact address
84  * @mgr: Manager object
85  * @start: Start address (page-based, not byte-based)
86  * @pages: Size of object (page-based)
87  *
88  * Same as drm_vma_offset_lookup_locked() but does not allow any offset into the node.
89  * It only returns the exact object with the given start address.
90  *
91  * RETURNS:
92  * Node at exact start address @start.
93  */
94 static inline struct drm_vma_offset_node *
drm_vma_offset_exact_lookup_locked(struct drm_vma_offset_manager * mgr,unsigned long start,unsigned long pages)95 drm_vma_offset_exact_lookup_locked(struct drm_vma_offset_manager *mgr,
96 				   unsigned long start,
97 				   unsigned long pages)
98 {
99 	struct drm_vma_offset_node *node;
100 
101 	node = drm_vma_offset_lookup_locked(mgr, start, pages);
102 	return (node && node->vm_node.start == start) ? node : NULL;
103 }
104 
105 /**
106  * drm_vma_offset_lock_lookup() - Lock lookup for extended private use
107  * @mgr: Manager object
108  *
109  * Lock VMA manager for extended lookups. Only locked VMA function calls
110  * are allowed while holding this lock. All other contexts are blocked from VMA
111  * until the lock is released via drm_vma_offset_unlock_lookup().
112  *
113  * Use this if you need to take a reference to the objects returned by
114  * drm_vma_offset_lookup_locked() before releasing this lock again.
115  *
116  * This lock must not be used for anything else than extended lookups. You must
117  * not call any other VMA helpers while holding this lock.
118  *
119  * Note: You're in atomic-context while holding this lock!
120  */
drm_vma_offset_lock_lookup(struct drm_vma_offset_manager * mgr)121 static inline void drm_vma_offset_lock_lookup(struct drm_vma_offset_manager *mgr)
122 {
123 	read_lock(&mgr->vm_lock);
124 }
125 
126 /**
127  * drm_vma_offset_unlock_lookup() - Unlock lookup for extended private use
128  * @mgr: Manager object
129  *
130  * Release lookup-lock. See drm_vma_offset_lock_lookup() for more information.
131  */
drm_vma_offset_unlock_lookup(struct drm_vma_offset_manager * mgr)132 static inline void drm_vma_offset_unlock_lookup(struct drm_vma_offset_manager *mgr)
133 {
134 	read_unlock(&mgr->vm_lock);
135 }
136 
137 /**
138  * drm_vma_node_reset() - Initialize or reset node object
139  * @node: Node to initialize or reset
140  *
141  * Reset a node to its initial state. This must be called before using it with
142  * any VMA offset manager.
143  *
144  * This must not be called on an already allocated node, or you will leak
145  * memory.
146  */
drm_vma_node_reset(struct drm_vma_offset_node * node)147 static inline void drm_vma_node_reset(struct drm_vma_offset_node *node)
148 {
149 	memset(node, 0, sizeof(*node));
150 	node->vm_files = RB_ROOT;
151 	rwlock_init(&node->vm_lock);
152 }
153 
154 /**
155  * drm_vma_node_start() - Return start address for page-based addressing
156  * @node: Node to inspect
157  *
158  * Return the start address of the given node. This can be used as offset into
159  * the linear VM space that is provided by the VMA offset manager. Note that
160  * this can only be used for page-based addressing. If you need a proper offset
161  * for user-space mappings, you must apply "<< PAGE_SHIFT" or use the
162  * drm_vma_node_offset_addr() helper instead.
163  *
164  * RETURNS:
165  * Start address of @node for page-based addressing. 0 if the node does not
166  * have an offset allocated.
167  */
drm_vma_node_start(const struct drm_vma_offset_node * node)168 static inline unsigned long drm_vma_node_start(const struct drm_vma_offset_node *node)
169 {
170 	return node->vm_node.start;
171 }
172 
173 /**
174  * drm_vma_node_size() - Return size (page-based)
175  * @node: Node to inspect
176  *
177  * Return the size as number of pages for the given node. This is the same size
178  * that was passed to drm_vma_offset_add(). If no offset is allocated for the
179  * node, this is 0.
180  *
181  * RETURNS:
182  * Size of @node as number of pages. 0 if the node does not have an offset
183  * allocated.
184  */
drm_vma_node_size(struct drm_vma_offset_node * node)185 static inline unsigned long drm_vma_node_size(struct drm_vma_offset_node *node)
186 {
187 	return node->vm_node.size;
188 }
189 
190 /**
191  * drm_vma_node_offset_addr() - Return sanitized offset for user-space mmaps
192  * @node: Linked offset node
193  *
194  * Same as drm_vma_node_start() but returns the address as a valid offset that
195  * can be used for user-space mappings during mmap().
196  * This must not be called on unlinked nodes.
197  *
198  * RETURNS:
199  * Offset of @node for byte-based addressing. 0 if the node does not have an
200  * object allocated.
201  */
drm_vma_node_offset_addr(struct drm_vma_offset_node * node)202 static inline __u64 drm_vma_node_offset_addr(struct drm_vma_offset_node *node)
203 {
204 	return ((__u64)node->vm_node.start) << PAGE_SHIFT;
205 }
206 
207 /**
208  * drm_vma_node_unmap() - Unmap offset node
209  * @node: Offset node
210  * @file_mapping: Address space to unmap @node from
211  *
212  * Unmap all userspace mappings for a given offset node. The mappings must be
213  * associated with the @file_mapping address-space. If no offset exists
214  * nothing is done.
215  *
216  * This call is unlocked. The caller must guarantee that drm_vma_offset_remove()
217  * is not called on this node concurrently.
218  */
drm_vma_node_unmap(struct drm_vma_offset_node * node,struct address_space * file_mapping)219 static inline void drm_vma_node_unmap(struct drm_vma_offset_node *node,
220 				      struct address_space *file_mapping)
221 {
222 	if (drm_mm_node_allocated(&node->vm_node))
223 		unmap_mapping_range(file_mapping,
224 				    drm_vma_node_offset_addr(node),
225 				    drm_vma_node_size(node) << PAGE_SHIFT, 1);
226 }
227 
228 /**
229  * drm_vma_node_verify_access() - Access verification helper for TTM
230  * @node: Offset node
231  * @tag: Tag of file to check
232  *
233  * This checks whether @tag is granted access to @node. It is the same as
234  * drm_vma_node_is_allowed() but suitable as drop-in helper for TTM
235  * verify_access() callbacks.
236  *
237  * RETURNS:
238  * 0 if access is granted, -EACCES otherwise.
239  */
drm_vma_node_verify_access(struct drm_vma_offset_node * node,struct drm_file * tag)240 static inline int drm_vma_node_verify_access(struct drm_vma_offset_node *node,
241 					     struct drm_file *tag)
242 {
243 	return drm_vma_node_is_allowed(node, tag) ? 0 : -EACCES;
244 }
245 
246 #endif /* __DRM_VMA_MANAGER_H__ */
247