1  // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2  /******************************************************************************
3   *
4   * Module Name: exmutex - ASL Mutex Acquire/Release functions
5   *
6   * Copyright (C) 2000 - 2023, Intel Corp.
7   *
8   *****************************************************************************/
9  
10  #include <acpi/acpi.h>
11  #include "accommon.h"
12  #include "acinterp.h"
13  #include "acevents.h"
14  
15  #define _COMPONENT          ACPI_EXECUTER
16  ACPI_MODULE_NAME("exmutex")
17  
18  /* Local prototypes */
19  static void
20  acpi_ex_link_mutex(union acpi_operand_object *obj_desc,
21  		   struct acpi_thread_state *thread);
22  
23  /*******************************************************************************
24   *
25   * FUNCTION:    acpi_ex_unlink_mutex
26   *
27   * PARAMETERS:  obj_desc            - The mutex to be unlinked
28   *
29   * RETURN:      None
30   *
31   * DESCRIPTION: Remove a mutex from the "AcquiredMutex" list
32   *
33   ******************************************************************************/
34  
acpi_ex_unlink_mutex(union acpi_operand_object * obj_desc)35  void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc)
36  {
37  	struct acpi_thread_state *thread = obj_desc->mutex.owner_thread;
38  
39  	if (!thread) {
40  		return;
41  	}
42  
43  	/* Doubly linked list */
44  
45  	if (obj_desc->mutex.next) {
46  		(obj_desc->mutex.next)->mutex.prev = obj_desc->mutex.prev;
47  	}
48  
49  	if (obj_desc->mutex.prev) {
50  		(obj_desc->mutex.prev)->mutex.next = obj_desc->mutex.next;
51  
52  		/*
53  		 * Migrate the previous sync level associated with this mutex to
54  		 * the previous mutex on the list so that it may be preserved.
55  		 * This handles the case where several mutexes have been acquired
56  		 * at the same level, but are not released in opposite order.
57  		 */
58  		(obj_desc->mutex.prev)->mutex.original_sync_level =
59  		    obj_desc->mutex.original_sync_level;
60  	} else {
61  		thread->acquired_mutex_list = obj_desc->mutex.next;
62  	}
63  }
64  
65  /*******************************************************************************
66   *
67   * FUNCTION:    acpi_ex_link_mutex
68   *
69   * PARAMETERS:  obj_desc            - The mutex to be linked
70   *              thread              - Current executing thread object
71   *
72   * RETURN:      None
73   *
74   * DESCRIPTION: Add a mutex to the "AcquiredMutex" list for this walk
75   *
76   ******************************************************************************/
77  
78  static void
acpi_ex_link_mutex(union acpi_operand_object * obj_desc,struct acpi_thread_state * thread)79  acpi_ex_link_mutex(union acpi_operand_object *obj_desc,
80  		   struct acpi_thread_state *thread)
81  {
82  	union acpi_operand_object *list_head;
83  
84  	list_head = thread->acquired_mutex_list;
85  
86  	/* This object will be the first object in the list */
87  
88  	obj_desc->mutex.prev = NULL;
89  	obj_desc->mutex.next = list_head;
90  
91  	/* Update old first object to point back to this object */
92  
93  	if (list_head) {
94  		list_head->mutex.prev = obj_desc;
95  	}
96  
97  	/* Update list head */
98  
99  	thread->acquired_mutex_list = obj_desc;
100  }
101  
102  /*******************************************************************************
103   *
104   * FUNCTION:    acpi_ex_acquire_mutex_object
105   *
106   * PARAMETERS:  timeout             - Timeout in milliseconds
107   *              obj_desc            - Mutex object
108   *              thread_id           - Current thread state
109   *
110   * RETURN:      Status
111   *
112   * DESCRIPTION: Acquire an AML mutex, low-level interface. Provides a common
113   *              path that supports multiple acquires by the same thread.
114   *
115   * MUTEX:       Interpreter must be locked
116   *
117   * NOTE: This interface is called from three places:
118   * 1) From acpi_ex_acquire_mutex, via an AML Acquire() operator
119   * 2) From acpi_ex_acquire_global_lock when an AML Field access requires the
120   *    global lock
121   * 3) From the external interface, acpi_acquire_global_lock
122   *
123   ******************************************************************************/
124  
125  acpi_status
acpi_ex_acquire_mutex_object(u16 timeout,union acpi_operand_object * obj_desc,acpi_thread_id thread_id)126  acpi_ex_acquire_mutex_object(u16 timeout,
127  			     union acpi_operand_object *obj_desc,
128  			     acpi_thread_id thread_id)
129  {
130  	acpi_status status;
131  
132  	ACPI_FUNCTION_TRACE_PTR(ex_acquire_mutex_object, obj_desc);
133  
134  	if (!obj_desc) {
135  		return_ACPI_STATUS(AE_BAD_PARAMETER);
136  	}
137  
138  	/* Support for multiple acquires by the owning thread */
139  
140  	if (obj_desc->mutex.thread_id == thread_id) {
141  		/*
142  		 * The mutex is already owned by this thread, just increment the
143  		 * acquisition depth
144  		 */
145  		obj_desc->mutex.acquisition_depth++;
146  		return_ACPI_STATUS(AE_OK);
147  	}
148  
149  	/* Acquire the mutex, wait if necessary. Special case for Global Lock */
150  
151  	if (obj_desc == acpi_gbl_global_lock_mutex) {
152  		status = acpi_ev_acquire_global_lock(timeout);
153  	} else {
154  		status =
155  		    acpi_ex_system_wait_mutex(obj_desc->mutex.os_mutex,
156  					      timeout);
157  	}
158  
159  	if (ACPI_FAILURE(status)) {
160  
161  		/* Includes failure from a timeout on time_desc */
162  
163  		return_ACPI_STATUS(status);
164  	}
165  
166  	/* Acquired the mutex: update mutex object */
167  
168  	obj_desc->mutex.thread_id = thread_id;
169  	obj_desc->mutex.acquisition_depth = 1;
170  	obj_desc->mutex.original_sync_level = 0;
171  	obj_desc->mutex.owner_thread = NULL;	/* Used only for AML Acquire() */
172  
173  	return_ACPI_STATUS(AE_OK);
174  }
175  
176  /*******************************************************************************
177   *
178   * FUNCTION:    acpi_ex_acquire_mutex
179   *
180   * PARAMETERS:  time_desc           - Timeout integer
181   *              obj_desc            - Mutex object
182   *              walk_state          - Current method execution state
183   *
184   * RETURN:      Status
185   *
186   * DESCRIPTION: Acquire an AML mutex
187   *
188   ******************************************************************************/
189  
190  acpi_status
acpi_ex_acquire_mutex(union acpi_operand_object * time_desc,union acpi_operand_object * obj_desc,struct acpi_walk_state * walk_state)191  acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
192  		      union acpi_operand_object *obj_desc,
193  		      struct acpi_walk_state *walk_state)
194  {
195  	acpi_status status;
196  
197  	ACPI_FUNCTION_TRACE_PTR(ex_acquire_mutex, obj_desc);
198  
199  	if (!obj_desc) {
200  		return_ACPI_STATUS(AE_BAD_PARAMETER);
201  	}
202  
203  	/* Must have a valid thread state struct */
204  
205  	if (!walk_state->thread) {
206  		ACPI_ERROR((AE_INFO,
207  			    "Cannot acquire Mutex [%4.4s], null thread info",
208  			    acpi_ut_get_node_name(obj_desc->mutex.node)));
209  		return_ACPI_STATUS(AE_AML_INTERNAL);
210  	}
211  
212  	/*
213  	 * Current sync level must be less than or equal to the sync level
214  	 * of the mutex. This mechanism provides some deadlock prevention.
215  	 */
216  	if (walk_state->thread->current_sync_level > obj_desc->mutex.sync_level) {
217  		ACPI_ERROR((AE_INFO,
218  			    "Cannot acquire Mutex [%4.4s], "
219  			    "current SyncLevel is too large (%u)",
220  			    acpi_ut_get_node_name(obj_desc->mutex.node),
221  			    walk_state->thread->current_sync_level));
222  		return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
223  	}
224  
225  	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
226  			  "Acquiring: Mutex SyncLevel %u, Thread SyncLevel %u, "
227  			  "Depth %u TID %p\n",
228  			  obj_desc->mutex.sync_level,
229  			  walk_state->thread->current_sync_level,
230  			  obj_desc->mutex.acquisition_depth,
231  			  walk_state->thread));
232  
233  	status = acpi_ex_acquire_mutex_object((u16)time_desc->integer.value,
234  					      obj_desc,
235  					      walk_state->thread->thread_id);
236  
237  	if (ACPI_SUCCESS(status) && obj_desc->mutex.acquisition_depth == 1) {
238  
239  		/* Save Thread object, original/current sync levels */
240  
241  		obj_desc->mutex.owner_thread = walk_state->thread;
242  		obj_desc->mutex.original_sync_level =
243  		    walk_state->thread->current_sync_level;
244  		walk_state->thread->current_sync_level =
245  		    obj_desc->mutex.sync_level;
246  
247  		/* Link the mutex to the current thread for force-unlock at method exit */
248  
249  		acpi_ex_link_mutex(obj_desc, walk_state->thread);
250  	}
251  
252  	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
253  			  "Acquired: Mutex SyncLevel %u, Thread SyncLevel %u, Depth %u\n",
254  			  obj_desc->mutex.sync_level,
255  			  walk_state->thread->current_sync_level,
256  			  obj_desc->mutex.acquisition_depth));
257  
258  	return_ACPI_STATUS(status);
259  }
260  
261  /*******************************************************************************
262   *
263   * FUNCTION:    acpi_ex_release_mutex_object
264   *
265   * PARAMETERS:  obj_desc            - The object descriptor for this op
266   *
267   * RETURN:      Status
268   *
269   * DESCRIPTION: Release a previously acquired Mutex, low level interface.
270   *              Provides a common path that supports multiple releases (after
271   *              previous multiple acquires) by the same thread.
272   *
273   * MUTEX:       Interpreter must be locked
274   *
275   * NOTE: This interface is called from three places:
276   * 1) From acpi_ex_release_mutex, via an AML Acquire() operator
277   * 2) From acpi_ex_release_global_lock when an AML Field access requires the
278   *    global lock
279   * 3) From the external interface, acpi_release_global_lock
280   *
281   ******************************************************************************/
282  
acpi_ex_release_mutex_object(union acpi_operand_object * obj_desc)283  acpi_status acpi_ex_release_mutex_object(union acpi_operand_object *obj_desc)
284  {
285  	acpi_status status = AE_OK;
286  
287  	ACPI_FUNCTION_TRACE(ex_release_mutex_object);
288  
289  	if (obj_desc->mutex.acquisition_depth == 0) {
290  		return_ACPI_STATUS(AE_NOT_ACQUIRED);
291  	}
292  
293  	/* Match multiple Acquires with multiple Releases */
294  
295  	obj_desc->mutex.acquisition_depth--;
296  	if (obj_desc->mutex.acquisition_depth != 0) {
297  
298  		/* Just decrement the depth and return */
299  
300  		return_ACPI_STATUS(AE_OK);
301  	}
302  
303  	if (obj_desc->mutex.owner_thread) {
304  
305  		/* Unlink the mutex from the owner's list */
306  
307  		acpi_ex_unlink_mutex(obj_desc);
308  		obj_desc->mutex.owner_thread = NULL;
309  	}
310  
311  	/* Release the mutex, special case for Global Lock */
312  
313  	if (obj_desc == acpi_gbl_global_lock_mutex) {
314  		status = acpi_ev_release_global_lock();
315  	} else {
316  		acpi_os_release_mutex(obj_desc->mutex.os_mutex);
317  	}
318  
319  	/* Clear mutex info */
320  
321  	obj_desc->mutex.thread_id = 0;
322  	return_ACPI_STATUS(status);
323  }
324  
325  /*******************************************************************************
326   *
327   * FUNCTION:    acpi_ex_release_mutex
328   *
329   * PARAMETERS:  obj_desc            - The object descriptor for this op
330   *              walk_state          - Current method execution state
331   *
332   * RETURN:      Status
333   *
334   * DESCRIPTION: Release a previously acquired Mutex.
335   *
336   ******************************************************************************/
337  
338  acpi_status
acpi_ex_release_mutex(union acpi_operand_object * obj_desc,struct acpi_walk_state * walk_state)339  acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
340  		      struct acpi_walk_state *walk_state)
341  {
342  	u8 previous_sync_level;
343  	struct acpi_thread_state *owner_thread;
344  	acpi_status status = AE_OK;
345  
346  	ACPI_FUNCTION_TRACE(ex_release_mutex);
347  
348  	if (!obj_desc) {
349  		return_ACPI_STATUS(AE_BAD_PARAMETER);
350  	}
351  
352  	owner_thread = obj_desc->mutex.owner_thread;
353  
354  	/* The mutex must have been previously acquired in order to release it */
355  
356  	if (!owner_thread) {
357  		ACPI_ERROR((AE_INFO,
358  			    "Cannot release Mutex [%4.4s], not acquired",
359  			    acpi_ut_get_node_name(obj_desc->mutex.node)));
360  		return_ACPI_STATUS(AE_AML_MUTEX_NOT_ACQUIRED);
361  	}
362  
363  	/* Must have a valid thread ID */
364  
365  	if (!walk_state->thread) {
366  		ACPI_ERROR((AE_INFO,
367  			    "Cannot release Mutex [%4.4s], null thread info",
368  			    acpi_ut_get_node_name(obj_desc->mutex.node)));
369  		return_ACPI_STATUS(AE_AML_INTERNAL);
370  	}
371  
372  	/*
373  	 * The Mutex is owned, but this thread must be the owner.
374  	 * Special case for Global Lock, any thread can release
375  	 */
376  	if ((owner_thread->thread_id != walk_state->thread->thread_id) &&
377  	    (obj_desc != acpi_gbl_global_lock_mutex)) {
378  		ACPI_ERROR((AE_INFO,
379  			    "Thread %u cannot release Mutex [%4.4s] acquired by thread %u",
380  			    (u32)walk_state->thread->thread_id,
381  			    acpi_ut_get_node_name(obj_desc->mutex.node),
382  			    (u32)owner_thread->thread_id));
383  		return_ACPI_STATUS(AE_AML_NOT_OWNER);
384  	}
385  
386  	/*
387  	 * The sync level of the mutex must be equal to the current sync level. In
388  	 * other words, the current level means that at least one mutex at that
389  	 * level is currently being held. Attempting to release a mutex of a
390  	 * different level can only mean that the mutex ordering rule is being
391  	 * violated. This behavior is clarified in ACPI 4.0 specification.
392  	 */
393  	if (obj_desc->mutex.sync_level != owner_thread->current_sync_level) {
394  		ACPI_ERROR((AE_INFO,
395  			    "Cannot release Mutex [%4.4s], SyncLevel mismatch: "
396  			    "mutex %u current %u",
397  			    acpi_ut_get_node_name(obj_desc->mutex.node),
398  			    obj_desc->mutex.sync_level,
399  			    walk_state->thread->current_sync_level));
400  		return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
401  	}
402  
403  	/*
404  	 * Get the previous sync_level from the head of the acquired mutex list.
405  	 * This handles the case where several mutexes at the same level have been
406  	 * acquired, but are not released in reverse order.
407  	 */
408  	previous_sync_level =
409  	    owner_thread->acquired_mutex_list->mutex.original_sync_level;
410  
411  	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
412  			  "Releasing: Object SyncLevel %u, Thread SyncLevel %u, "
413  			  "Prev SyncLevel %u, Depth %u TID %p\n",
414  			  obj_desc->mutex.sync_level,
415  			  walk_state->thread->current_sync_level,
416  			  previous_sync_level,
417  			  obj_desc->mutex.acquisition_depth,
418  			  walk_state->thread));
419  
420  	status = acpi_ex_release_mutex_object(obj_desc);
421  	if (ACPI_FAILURE(status)) {
422  		return_ACPI_STATUS(status);
423  	}
424  
425  	if (obj_desc->mutex.acquisition_depth == 0) {
426  
427  		/* Restore the previous sync_level */
428  
429  		owner_thread->current_sync_level = previous_sync_level;
430  	}
431  
432  	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
433  			  "Released: Object SyncLevel %u, Thread SyncLevel, %u, "
434  			  "Prev SyncLevel %u, Depth %u\n",
435  			  obj_desc->mutex.sync_level,
436  			  walk_state->thread->current_sync_level,
437  			  previous_sync_level,
438  			  obj_desc->mutex.acquisition_depth));
439  
440  	return_ACPI_STATUS(status);
441  }
442  
443  /*******************************************************************************
444   *
445   * FUNCTION:    acpi_ex_release_all_mutexes
446   *
447   * PARAMETERS:  thread              - Current executing thread object
448   *
449   * RETURN:      Status
450   *
451   * DESCRIPTION: Release all mutexes held by this thread
452   *
453   * NOTE: This function is called as the thread is exiting the interpreter.
454   * Mutexes are not released when an individual control method is exited, but
455   * only when the parent thread actually exits the interpreter. This allows one
456   * method to acquire a mutex, and a different method to release it, as long as
457   * this is performed underneath a single parent control method.
458   *
459   ******************************************************************************/
460  
acpi_ex_release_all_mutexes(struct acpi_thread_state * thread)461  void acpi_ex_release_all_mutexes(struct acpi_thread_state *thread)
462  {
463  	union acpi_operand_object *next = thread->acquired_mutex_list;
464  	union acpi_operand_object *obj_desc;
465  
466  	ACPI_FUNCTION_TRACE(ex_release_all_mutexes);
467  
468  	/* Traverse the list of owned mutexes, releasing each one */
469  
470  	while (next) {
471  		obj_desc = next;
472  		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
473  				  "Mutex [%4.4s] force-release, SyncLevel %u Depth %u\n",
474  				  obj_desc->mutex.node->name.ascii,
475  				  obj_desc->mutex.sync_level,
476  				  obj_desc->mutex.acquisition_depth));
477  
478  		/* Release the mutex, special case for Global Lock */
479  
480  		if (obj_desc == acpi_gbl_global_lock_mutex) {
481  
482  			/* Ignore errors */
483  
484  			(void)acpi_ev_release_global_lock();
485  		} else {
486  			acpi_os_release_mutex(obj_desc->mutex.os_mutex);
487  		}
488  
489  		/* Update Thread sync_level (Last mutex is the important one) */
490  
491  		thread->current_sync_level =
492  		    obj_desc->mutex.original_sync_level;
493  
494  		/* Mark mutex unowned */
495  
496  		next = obj_desc->mutex.next;
497  
498  		obj_desc->mutex.prev = NULL;
499  		obj_desc->mutex.next = NULL;
500  		obj_desc->mutex.acquisition_depth = 0;
501  		obj_desc->mutex.owner_thread = NULL;
502  		obj_desc->mutex.thread_id = 0;
503  	}
504  
505  	return_VOID;
506  }
507