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27 /*
28  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29  */
30 /** @file ttm_object.h
31  *
32  * Base- and reference object implementation for the various
33  * ttm objects. Implements reference counting, minimal security checks
34  * and release on file close.
35  */
36 
37 #ifndef _TTM_OBJECT_H_
38 #define _TTM_OBJECT_H_
39 
40 #include <linux/dma-buf.h>
41 #include <linux/kref.h>
42 #include <linux/list.h>
43 #include <linux/rcupdate.h>
44 
45 #include <drm/drm_hashtab.h>
46 #include <drm/ttm/ttm_memory.h>
47 
48 /**
49  * enum ttm_ref_type
50  *
51  * Describes what type of reference a ref object holds.
52  *
53  * TTM_REF_USAGE is a simple refcount on a base object.
54  *
55  * TTM_REF_SYNCCPU_READ is a SYNCCPU_READ reference on a
56  * buffer object.
57  *
58  * TTM_REF_SYNCCPU_WRITE is a SYNCCPU_WRITE reference on a
59  * buffer object.
60  *
61  */
62 
63 enum ttm_ref_type {
64 	TTM_REF_USAGE,
65 	TTM_REF_SYNCCPU_READ,
66 	TTM_REF_SYNCCPU_WRITE,
67 	TTM_REF_NUM
68 };
69 
70 /**
71  * enum ttm_object_type
72  *
73  * One entry per ttm object type.
74  * Device-specific types should use the
75  * ttm_driver_typex types.
76  */
77 
78 enum ttm_object_type {
79 	ttm_fence_type,
80 	ttm_buffer_type,
81 	ttm_lock_type,
82 	ttm_prime_type,
83 	ttm_driver_type0 = 256,
84 	ttm_driver_type1,
85 	ttm_driver_type2,
86 	ttm_driver_type3,
87 	ttm_driver_type4,
88 	ttm_driver_type5
89 };
90 
91 struct ttm_object_file;
92 struct ttm_object_device;
93 
94 /**
95  * struct ttm_base_object
96  *
97  * @hash: hash entry for the per-device object hash.
98  * @type: derived type this object is base class for.
99  * @shareable: Other ttm_object_files can access this object.
100  *
101  * @tfile: Pointer to ttm_object_file of the creator.
102  * NULL if the object was not created by a user request.
103  * (kernel object).
104  *
105  * @refcount: Number of references to this object, not
106  * including the hash entry. A reference to a base object can
107  * only be held by a ref object.
108  *
109  * @refcount_release: A function to be called when there are
110  * no more references to this object. This function should
111  * destroy the object (or make sure destruction eventually happens),
112  * and when it is called, the object has
113  * already been taken out of the per-device hash. The parameter
114  * "base" should be set to NULL by the function.
115  *
116  * @ref_obj_release: A function to be called when a reference object
117  * with another ttm_ref_type than TTM_REF_USAGE is deleted.
118  * This function may, for example, release a lock held by a user-space
119  * process.
120  *
121  * This struct is intended to be used as a base struct for objects that
122  * are visible to user-space. It provides a global name, race-safe
123  * access and refcounting, minimal access contol and hooks for unref actions.
124  */
125 
126 struct ttm_base_object {
127 	struct rcu_head rhead;
128 	struct ttm_object_file *tfile;
129 	struct kref refcount;
130 	void (*refcount_release) (struct ttm_base_object **base);
131 	void (*ref_obj_release) (struct ttm_base_object *base,
132 				 enum ttm_ref_type ref_type);
133 	u32 handle;
134 	enum ttm_object_type object_type;
135 	u32 shareable;
136 };
137 
138 
139 /**
140  * struct ttm_prime_object - Modified base object that is prime-aware
141  *
142  * @base: struct ttm_base_object that we derive from
143  * @mutex: Mutex protecting the @dma_buf member.
144  * @size: Size of the dma_buf associated with this object
145  * @real_type: Type of the underlying object. Needed since we're setting
146  * the value of @base::object_type to ttm_prime_type
147  * @dma_buf: Non ref-coutned pointer to a struct dma_buf created from this
148  * object.
149  * @refcount_release: The underlying object's release method. Needed since
150  * we set @base::refcount_release to our own release method.
151  */
152 
153 struct ttm_prime_object {
154 	struct ttm_base_object base;
155 	struct mutex mutex;
156 	size_t size;
157 	enum ttm_object_type real_type;
158 	struct dma_buf *dma_buf;
159 	void (*refcount_release) (struct ttm_base_object **);
160 };
161 
162 /**
163  * ttm_base_object_init
164  *
165  * @tfile: Pointer to a struct ttm_object_file.
166  * @base: The struct ttm_base_object to initialize.
167  * @shareable: This object is shareable with other applcations.
168  * (different @tfile pointers.)
169  * @type: The object type.
170  * @refcount_release: See the struct ttm_base_object description.
171  * @ref_obj_release: See the struct ttm_base_object description.
172  *
173  * Initializes a struct ttm_base_object.
174  */
175 
176 extern int ttm_base_object_init(struct ttm_object_file *tfile,
177 				struct ttm_base_object *base,
178 				bool shareable,
179 				enum ttm_object_type type,
180 				void (*refcount_release) (struct ttm_base_object
181 							  **),
182 				void (*ref_obj_release) (struct ttm_base_object
183 							 *,
184 							 enum ttm_ref_type
185 							 ref_type));
186 
187 /**
188  * ttm_base_object_lookup
189  *
190  * @tfile: Pointer to a struct ttm_object_file.
191  * @key: Hash key
192  *
193  * Looks up a struct ttm_base_object with the key @key.
194  */
195 
196 extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
197 						      *tfile, uint32_t key);
198 
199 /**
200  * ttm_base_object_lookup_for_ref
201  *
202  * @tdev: Pointer to a struct ttm_object_device.
203  * @key: Hash key
204  *
205  * Looks up a struct ttm_base_object with the key @key.
206  * This function should only be used when the struct tfile associated with the
207  * caller doesn't yet have a reference to the base object.
208  */
209 
210 extern struct ttm_base_object *
211 ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key);
212 
213 /**
214  * ttm_base_object_unref
215  *
216  * @p_base: Pointer to a pointer referencing a struct ttm_base_object.
217  *
218  * Decrements the base object refcount and clears the pointer pointed to by
219  * p_base.
220  */
221 
222 extern void ttm_base_object_unref(struct ttm_base_object **p_base);
223 
224 /**
225  * ttm_ref_object_add.
226  *
227  * @tfile: A struct ttm_object_file representing the application owning the
228  * ref_object.
229  * @base: The base object to reference.
230  * @ref_type: The type of reference.
231  * @existed: Upon completion, indicates that an identical reference object
232  * already existed, and the refcount was upped on that object instead.
233  * @require_existed: Fail with -EPERM if an identical ref object didn't
234  * already exist.
235  *
236  * Checks that the base object is shareable and adds a ref object to it.
237  *
238  * Adding a ref object to a base object is basically like referencing the
239  * base object, but a user-space application holds the reference. When the
240  * file corresponding to @tfile is closed, all its reference objects are
241  * deleted. A reference object can have different types depending on what
242  * it's intended for. It can be refcounting to prevent object destruction,
243  * When user-space takes a lock, it can add a ref object to that lock to
244  * make sure the lock is released if the application dies. A ref object
245  * will hold a single reference on a base object.
246  */
247 extern int ttm_ref_object_add(struct ttm_object_file *tfile,
248 			      struct ttm_base_object *base,
249 			      enum ttm_ref_type ref_type, bool *existed,
250 			      bool require_existed);
251 
252 extern bool ttm_ref_object_exists(struct ttm_object_file *tfile,
253 				  struct ttm_base_object *base);
254 
255 /**
256  * ttm_ref_object_base_unref
257  *
258  * @key: Key representing the base object.
259  * @ref_type: Ref type of the ref object to be dereferenced.
260  *
261  * Unreference a ref object with type @ref_type
262  * on the base object identified by @key. If there are no duplicate
263  * references, the ref object will be destroyed and the base object
264  * will be unreferenced.
265  */
266 extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
267 				     unsigned long key,
268 				     enum ttm_ref_type ref_type);
269 
270 /**
271  * ttm_object_file_init - initialize a struct ttm_object file
272  *
273  * @tdev: A struct ttm_object device this file is initialized on.
274  * @hash_order: Order of the hash table used to hold the reference objects.
275  *
276  * This is typically called by the file_ops::open function.
277  */
278 
279 extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
280 						    *tdev,
281 						    unsigned int hash_order);
282 
283 /**
284  * ttm_object_file_release - release data held by a ttm_object_file
285  *
286  * @p_tfile: Pointer to pointer to the ttm_object_file object to release.
287  * *p_tfile will be set to NULL by this function.
288  *
289  * Releases all data associated by a ttm_object_file.
290  * Typically called from file_ops::release. The caller must
291  * ensure that there are no concurrent users of tfile.
292  */
293 
294 extern void ttm_object_file_release(struct ttm_object_file **p_tfile);
295 
296 /**
297  * ttm_object device init - initialize a struct ttm_object_device
298  *
299  * @mem_glob: struct ttm_mem_global for memory accounting.
300  * @hash_order: Order of hash table used to hash the base objects.
301  * @ops: DMA buf ops for prime objects of this device.
302  *
303  * This function is typically called on device initialization to prepare
304  * data structures needed for ttm base and ref objects.
305  */
306 
307 extern struct ttm_object_device *
308 ttm_object_device_init(struct ttm_mem_global *mem_glob,
309 		       unsigned int hash_order,
310 		       const struct dma_buf_ops *ops);
311 
312 /**
313  * ttm_object_device_release - release data held by a ttm_object_device
314  *
315  * @p_tdev: Pointer to pointer to the ttm_object_device object to release.
316  * *p_tdev will be set to NULL by this function.
317  *
318  * Releases all data associated by a ttm_object_device.
319  * Typically called from driver::unload before the destruction of the
320  * device private data structure.
321  */
322 
323 extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
324 
325 #define ttm_base_object_kfree(__object, __base)\
326 	kfree_rcu(__object, __base.rhead)
327 
328 extern int ttm_prime_object_init(struct ttm_object_file *tfile,
329 				 size_t size,
330 				 struct ttm_prime_object *prime,
331 				 bool shareable,
332 				 enum ttm_object_type type,
333 				 void (*refcount_release)
334 				 (struct ttm_base_object **),
335 				 void (*ref_obj_release)
336 				 (struct ttm_base_object *,
337 				  enum ttm_ref_type ref_type));
338 
339 static inline enum ttm_object_type
340 ttm_base_object_type(struct ttm_base_object *base)
341 {
342 	return (base->object_type == ttm_prime_type) ?
343 		container_of(base, struct ttm_prime_object, base)->real_type :
344 		base->object_type;
345 }
346 extern int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
347 				  int fd, u32 *handle);
348 extern int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
349 				  uint32_t handle, uint32_t flags,
350 				  int *prime_fd);
351 
352 #define ttm_prime_object_kfree(__obj, __prime)		\
353 	kfree_rcu(__obj, __prime.base.rhead)
354 
355 /*
356  * Extra memory required by the base object's idr storage, which is allocated
357  * separately from the base object itself. We estimate an on-average 128 bytes
358  * per idr.
359  */
360 #define TTM_OBJ_EXTRA_SIZE 128
361 
362 struct ttm_base_object *
363 ttm_base_object_noref_lookup(struct ttm_object_file *tfile, uint32_t key);
364 
365 /**
366  * ttm_base_object_noref_release - release a base object pointer looked up
367  * without reference
368  *
369  * Releases a base object pointer looked up with ttm_base_object_noref_lookup().
370  */
371 static inline void ttm_base_object_noref_release(void)
372 {
373 	__acquire(RCU);
374 	rcu_read_unlock();
375 }
376 #endif
377