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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 
47 #include "ttm_memory.h"
48 
49 /**
50  * enum ttm_ref_type
51  *
52  * Describes what type of reference a ref object holds.
53  *
54  * TTM_REF_USAGE is a simple refcount on a base object.
55  *
56  * TTM_REF_SYNCCPU_READ is a SYNCCPU_READ reference on a
57  * buffer object.
58  *
59  * TTM_REF_SYNCCPU_WRITE is a SYNCCPU_WRITE reference on a
60  * buffer object.
61  *
62  */
63 
64 enum ttm_ref_type {
65 	TTM_REF_USAGE,
66 	TTM_REF_SYNCCPU_READ,
67 	TTM_REF_SYNCCPU_WRITE,
68 	TTM_REF_NUM
69 };
70 
71 /**
72  * enum ttm_object_type
73  *
74  * One entry per ttm object type.
75  * Device-specific types should use the
76  * ttm_driver_typex types.
77  */
78 
79 enum ttm_object_type {
80 	ttm_fence_type,
81 	ttm_buffer_type,
82 	ttm_lock_type,
83 	ttm_prime_type,
84 	ttm_driver_type0 = 256,
85 	ttm_driver_type1,
86 	ttm_driver_type2,
87 	ttm_driver_type3,
88 	ttm_driver_type4,
89 	ttm_driver_type5
90 };
91 
92 struct ttm_object_file;
93 struct ttm_object_device;
94 
95 /**
96  * struct ttm_base_object
97  *
98  * @hash: hash entry for the per-device object hash.
99  * @type: derived type this object is base class for.
100  * @shareable: Other ttm_object_files can access this object.
101  *
102  * @tfile: Pointer to ttm_object_file of the creator.
103  * NULL if the object was not created by a user request.
104  * (kernel object).
105  *
106  * @refcount: Number of references to this object, not
107  * including the hash entry. A reference to a base object can
108  * only be held by a ref object.
109  *
110  * @refcount_release: A function to be called when there are
111  * no more references to this object. This function should
112  * destroy the object (or make sure destruction eventually happens),
113  * and when it is called, the object has
114  * already been taken out of the per-device hash. The parameter
115  * "base" should be set to NULL by the function.
116  *
117  * @ref_obj_release: A function to be called when a reference object
118  * with another ttm_ref_type than TTM_REF_USAGE is deleted.
119  * This function may, for example, release a lock held by a user-space
120  * process.
121  *
122  * This struct is intended to be used as a base struct for objects that
123  * are visible to user-space. It provides a global name, race-safe
124  * access and refcounting, minimal access contol and hooks for unref actions.
125  */
126 
127 struct ttm_base_object {
128 	struct rcu_head rhead;
129 	struct ttm_object_file *tfile;
130 	struct kref refcount;
131 	void (*refcount_release) (struct ttm_base_object **base);
132 	void (*ref_obj_release) (struct ttm_base_object *base,
133 				 enum ttm_ref_type ref_type);
134 	u32 handle;
135 	enum ttm_object_type object_type;
136 	u32 shareable;
137 };
138 
139 
140 /**
141  * struct ttm_prime_object - Modified base object that is prime-aware
142  *
143  * @base: struct ttm_base_object that we derive from
144  * @mutex: Mutex protecting the @dma_buf member.
145  * @size: Size of the dma_buf associated with this object
146  * @real_type: Type of the underlying object. Needed since we're setting
147  * the value of @base::object_type to ttm_prime_type
148  * @dma_buf: Non ref-coutned pointer to a struct dma_buf created from this
149  * object.
150  * @refcount_release: The underlying object's release method. Needed since
151  * we set @base::refcount_release to our own release method.
152  */
153 
154 struct ttm_prime_object {
155 	struct ttm_base_object base;
156 	struct mutex mutex;
157 	size_t size;
158 	enum ttm_object_type real_type;
159 	struct dma_buf *dma_buf;
160 	void (*refcount_release) (struct ttm_base_object **);
161 };
162 
163 /**
164  * ttm_base_object_init
165  *
166  * @tfile: Pointer to a struct ttm_object_file.
167  * @base: The struct ttm_base_object to initialize.
168  * @shareable: This object is shareable with other applcations.
169  * (different @tfile pointers.)
170  * @type: The object type.
171  * @refcount_release: See the struct ttm_base_object description.
172  * @ref_obj_release: See the struct ttm_base_object description.
173  *
174  * Initializes a struct ttm_base_object.
175  */
176 
177 extern int ttm_base_object_init(struct ttm_object_file *tfile,
178 				struct ttm_base_object *base,
179 				bool shareable,
180 				enum ttm_object_type type,
181 				void (*refcount_release) (struct ttm_base_object
182 							  **),
183 				void (*ref_obj_release) (struct ttm_base_object
184 							 *,
185 							 enum ttm_ref_type
186 							 ref_type));
187 
188 /**
189  * ttm_base_object_lookup
190  *
191  * @tfile: Pointer to a struct ttm_object_file.
192  * @key: Hash key
193  *
194  * Looks up a struct ttm_base_object with the key @key.
195  */
196 
197 extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
198 						      *tfile, uint32_t key);
199 
200 /**
201  * ttm_base_object_lookup_for_ref
202  *
203  * @tdev: Pointer to a struct ttm_object_device.
204  * @key: Hash key
205  *
206  * Looks up a struct ttm_base_object with the key @key.
207  * This function should only be used when the struct tfile associated with the
208  * caller doesn't yet have a reference to the base object.
209  */
210 
211 extern struct ttm_base_object *
212 ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key);
213 
214 /**
215  * ttm_base_object_unref
216  *
217  * @p_base: Pointer to a pointer referencing a struct ttm_base_object.
218  *
219  * Decrements the base object refcount and clears the pointer pointed to by
220  * p_base.
221  */
222 
223 extern void ttm_base_object_unref(struct ttm_base_object **p_base);
224 
225 /**
226  * ttm_ref_object_add.
227  *
228  * @tfile: A struct ttm_object_file representing the application owning the
229  * ref_object.
230  * @base: The base object to reference.
231  * @ref_type: The type of reference.
232  * @existed: Upon completion, indicates that an identical reference object
233  * already existed, and the refcount was upped on that object instead.
234  * @require_existed: Fail with -EPERM if an identical ref object didn't
235  * already exist.
236  *
237  * Checks that the base object is shareable and adds a ref object to it.
238  *
239  * Adding a ref object to a base object is basically like referencing the
240  * base object, but a user-space application holds the reference. When the
241  * file corresponding to @tfile is closed, all its reference objects are
242  * deleted. A reference object can have different types depending on what
243  * it's intended for. It can be refcounting to prevent object destruction,
244  * When user-space takes a lock, it can add a ref object to that lock to
245  * make sure the lock is released if the application dies. A ref object
246  * will hold a single reference on a base object.
247  */
248 extern int ttm_ref_object_add(struct ttm_object_file *tfile,
249 			      struct ttm_base_object *base,
250 			      enum ttm_ref_type ref_type, bool *existed,
251 			      bool require_existed);
252 
253 extern bool ttm_ref_object_exists(struct ttm_object_file *tfile,
254 				  struct ttm_base_object *base);
255 
256 /**
257  * ttm_ref_object_base_unref
258  *
259  * @key: Key representing the base object.
260  * @ref_type: Ref type of the ref object to be dereferenced.
261  *
262  * Unreference a ref object with type @ref_type
263  * on the base object identified by @key. If there are no duplicate
264  * references, the ref object will be destroyed and the base object
265  * will be unreferenced.
266  */
267 extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
268 				     unsigned long key,
269 				     enum ttm_ref_type ref_type);
270 
271 /**
272  * ttm_object_file_init - initialize a struct ttm_object file
273  *
274  * @tdev: A struct ttm_object device this file is initialized on.
275  * @hash_order: Order of the hash table used to hold the reference objects.
276  *
277  * This is typically called by the file_ops::open function.
278  */
279 
280 extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
281 						    *tdev,
282 						    unsigned int hash_order);
283 
284 /**
285  * ttm_object_file_release - release data held by a ttm_object_file
286  *
287  * @p_tfile: Pointer to pointer to the ttm_object_file object to release.
288  * *p_tfile will be set to NULL by this function.
289  *
290  * Releases all data associated by a ttm_object_file.
291  * Typically called from file_ops::release. The caller must
292  * ensure that there are no concurrent users of tfile.
293  */
294 
295 extern void ttm_object_file_release(struct ttm_object_file **p_tfile);
296 
297 /**
298  * ttm_object device init - initialize a struct ttm_object_device
299  *
300  * @mem_glob: struct ttm_mem_global for memory accounting.
301  * @hash_order: Order of hash table used to hash the base objects.
302  * @ops: DMA buf ops for prime objects of this device.
303  *
304  * This function is typically called on device initialization to prepare
305  * data structures needed for ttm base and ref objects.
306  */
307 
308 extern struct ttm_object_device *
309 ttm_object_device_init(struct ttm_mem_global *mem_glob,
310 		       unsigned int hash_order,
311 		       const struct dma_buf_ops *ops);
312 
313 /**
314  * ttm_object_device_release - release data held by a ttm_object_device
315  *
316  * @p_tdev: Pointer to pointer to the ttm_object_device object to release.
317  * *p_tdev will be set to NULL by this function.
318  *
319  * Releases all data associated by a ttm_object_device.
320  * Typically called from driver::unload before the destruction of the
321  * device private data structure.
322  */
323 
324 extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
325 
326 #define ttm_base_object_kfree(__object, __base)\
327 	kfree_rcu(__object, __base.rhead)
328 
329 extern int ttm_prime_object_init(struct ttm_object_file *tfile,
330 				 size_t size,
331 				 struct ttm_prime_object *prime,
332 				 bool shareable,
333 				 enum ttm_object_type type,
334 				 void (*refcount_release)
335 				 (struct ttm_base_object **),
336 				 void (*ref_obj_release)
337 				 (struct ttm_base_object *,
338 				  enum ttm_ref_type ref_type));
339 
340 static inline enum ttm_object_type
341 ttm_base_object_type(struct ttm_base_object *base)
342 {
343 	return (base->object_type == ttm_prime_type) ?
344 		container_of(base, struct ttm_prime_object, base)->real_type :
345 		base->object_type;
346 }
347 extern int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
348 				  int fd, u32 *handle);
349 extern int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
350 				  uint32_t handle, uint32_t flags,
351 				  int *prime_fd);
352 
353 #define ttm_prime_object_kfree(__obj, __prime)		\
354 	kfree_rcu(__obj, __prime.base.rhead)
355 
356 /*
357  * Extra memory required by the base object's idr storage, which is allocated
358  * separately from the base object itself. We estimate an on-average 128 bytes
359  * per idr.
360  */
361 #define TTM_OBJ_EXTRA_SIZE 128
362 
363 struct ttm_base_object *
364 ttm_base_object_noref_lookup(struct ttm_object_file *tfile, uint32_t key);
365 
366 /**
367  * ttm_base_object_noref_release - release a base object pointer looked up
368  * without reference
369  *
370  * Releases a base object pointer looked up with ttm_base_object_noref_lookup().
371  */
372 static inline void ttm_base_object_noref_release(void)
373 {
374 	__acquire(RCU);
375 	rcu_read_unlock();
376 }
377 #endif
378