1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Runtime locking correctness validator
4 *
5 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
7 *
8 * see Documentation/locking/lockdep-design.txt for more details.
9 */
10 #ifndef __LINUX_LOCKDEP_H
11 #define __LINUX_LOCKDEP_H
12
13 struct task_struct;
14 struct lockdep_map;
15
16 /* for sysctl */
17 extern int prove_locking;
18 extern int lock_stat;
19
20 #define MAX_LOCKDEP_SUBCLASSES 8UL
21
22 #include <linux/types.h>
23
24 #ifdef CONFIG_LOCKDEP
25
26 #include <linux/linkage.h>
27 #include <linux/list.h>
28 #include <linux/debug_locks.h>
29 #include <linux/stacktrace.h>
30
31 /*
32 * We'd rather not expose kernel/lockdep_states.h this wide, but we do need
33 * the total number of states... :-(
34 */
35 #define XXX_LOCK_USAGE_STATES (1+2*4)
36
37 /*
38 * NR_LOCKDEP_CACHING_CLASSES ... Number of classes
39 * cached in the instance of lockdep_map
40 *
41 * Currently main class (subclass == 0) and signle depth subclass
42 * are cached in lockdep_map. This optimization is mainly targeting
43 * on rq->lock. double_rq_lock() acquires this highly competitive with
44 * single depth.
45 */
46 #define NR_LOCKDEP_CACHING_CLASSES 2
47
48 /*
49 * Lock-classes are keyed via unique addresses, by embedding the
50 * lockclass-key into the kernel (or module) .data section. (For
51 * static locks we use the lock address itself as the key.)
52 */
53 struct lockdep_subclass_key {
54 char __one_byte;
55 } __attribute__ ((__packed__));
56
57 struct lock_class_key {
58 struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES];
59 };
60
61 extern struct lock_class_key __lockdep_no_validate__;
62
63 #define LOCKSTAT_POINTS 4
64
65 /*
66 * The lock-class itself:
67 */
68 struct lock_class {
69 /*
70 * class-hash:
71 */
72 struct hlist_node hash_entry;
73
74 /*
75 * global list of all lock-classes:
76 */
77 struct list_head lock_entry;
78
79 struct lockdep_subclass_key *key;
80 unsigned int subclass;
81 unsigned int dep_gen_id;
82
83 /*
84 * IRQ/softirq usage tracking bits:
85 */
86 unsigned long usage_mask;
87 struct stack_trace usage_traces[XXX_LOCK_USAGE_STATES];
88
89 /*
90 * These fields represent a directed graph of lock dependencies,
91 * to every node we attach a list of "forward" and a list of
92 * "backward" graph nodes.
93 */
94 struct list_head locks_after, locks_before;
95
96 /*
97 * Generation counter, when doing certain classes of graph walking,
98 * to ensure that we check one node only once:
99 */
100 unsigned int version;
101
102 /*
103 * Statistics counter:
104 */
105 unsigned long ops;
106
107 const char *name;
108 int name_version;
109
110 #ifdef CONFIG_LOCK_STAT
111 unsigned long contention_point[LOCKSTAT_POINTS];
112 unsigned long contending_point[LOCKSTAT_POINTS];
113 #endif
114 };
115
116 #ifdef CONFIG_LOCK_STAT
117 struct lock_time {
118 s64 min;
119 s64 max;
120 s64 total;
121 unsigned long nr;
122 };
123
124 enum bounce_type {
125 bounce_acquired_write,
126 bounce_acquired_read,
127 bounce_contended_write,
128 bounce_contended_read,
129 nr_bounce_types,
130
131 bounce_acquired = bounce_acquired_write,
132 bounce_contended = bounce_contended_write,
133 };
134
135 struct lock_class_stats {
136 unsigned long contention_point[LOCKSTAT_POINTS];
137 unsigned long contending_point[LOCKSTAT_POINTS];
138 struct lock_time read_waittime;
139 struct lock_time write_waittime;
140 struct lock_time read_holdtime;
141 struct lock_time write_holdtime;
142 unsigned long bounces[nr_bounce_types];
143 };
144
145 struct lock_class_stats lock_stats(struct lock_class *class);
146 void clear_lock_stats(struct lock_class *class);
147 #endif
148
149 /*
150 * Map the lock object (the lock instance) to the lock-class object.
151 * This is embedded into specific lock instances:
152 */
153 struct lockdep_map {
154 struct lock_class_key *key;
155 struct lock_class *class_cache[NR_LOCKDEP_CACHING_CLASSES];
156 const char *name;
157 #ifdef CONFIG_LOCK_STAT
158 int cpu;
159 unsigned long ip;
160 #endif
161 };
162
lockdep_copy_map(struct lockdep_map * to,struct lockdep_map * from)163 static inline void lockdep_copy_map(struct lockdep_map *to,
164 struct lockdep_map *from)
165 {
166 int i;
167
168 *to = *from;
169 /*
170 * Since the class cache can be modified concurrently we could observe
171 * half pointers (64bit arch using 32bit copy insns). Therefore clear
172 * the caches and take the performance hit.
173 *
174 * XXX it doesn't work well with lockdep_set_class_and_subclass(), since
175 * that relies on cache abuse.
176 */
177 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
178 to->class_cache[i] = NULL;
179 }
180
181 /*
182 * Every lock has a list of other locks that were taken after it.
183 * We only grow the list, never remove from it:
184 */
185 struct lock_list {
186 struct list_head entry;
187 struct lock_class *class;
188 struct stack_trace trace;
189 int distance;
190
191 /*
192 * The parent field is used to implement breadth-first search, and the
193 * bit 0 is reused to indicate if the lock has been accessed in BFS.
194 */
195 struct lock_list *parent;
196 };
197
198 /*
199 * We record lock dependency chains, so that we can cache them:
200 */
201 struct lock_chain {
202 /* see BUILD_BUG_ON()s in lookup_chain_cache() */
203 unsigned int irq_context : 2,
204 depth : 6,
205 base : 24;
206 /* 4 byte hole */
207 struct hlist_node entry;
208 u64 chain_key;
209 };
210
211 #define MAX_LOCKDEP_KEYS_BITS 13
212 /*
213 * Subtract one because we offset hlock->class_idx by 1 in order
214 * to make 0 mean no class. This avoids overflowing the class_idx
215 * bitfield and hitting the BUG in hlock_class().
216 */
217 #define MAX_LOCKDEP_KEYS ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
218
219 struct held_lock {
220 /*
221 * One-way hash of the dependency chain up to this point. We
222 * hash the hashes step by step as the dependency chain grows.
223 *
224 * We use it for dependency-caching and we skip detection
225 * passes and dependency-updates if there is a cache-hit, so
226 * it is absolutely critical for 100% coverage of the validator
227 * to have a unique key value for every unique dependency path
228 * that can occur in the system, to make a unique hash value
229 * as likely as possible - hence the 64-bit width.
230 *
231 * The task struct holds the current hash value (initialized
232 * with zero), here we store the previous hash value:
233 */
234 u64 prev_chain_key;
235 unsigned long acquire_ip;
236 struct lockdep_map *instance;
237 struct lockdep_map *nest_lock;
238 #ifdef CONFIG_LOCK_STAT
239 u64 waittime_stamp;
240 u64 holdtime_stamp;
241 #endif
242 unsigned int class_idx:MAX_LOCKDEP_KEYS_BITS;
243 /*
244 * The lock-stack is unified in that the lock chains of interrupt
245 * contexts nest ontop of process context chains, but we 'separate'
246 * the hashes by starting with 0 if we cross into an interrupt
247 * context, and we also keep do not add cross-context lock
248 * dependencies - the lock usage graph walking covers that area
249 * anyway, and we'd just unnecessarily increase the number of
250 * dependencies otherwise. [Note: hardirq and softirq contexts
251 * are separated from each other too.]
252 *
253 * The following field is used to detect when we cross into an
254 * interrupt context:
255 */
256 unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
257 unsigned int trylock:1; /* 16 bits */
258
259 unsigned int read:2; /* see lock_acquire() comment */
260 unsigned int check:1; /* see lock_acquire() comment */
261 unsigned int hardirqs_off:1;
262 unsigned int references:12; /* 32 bits */
263 unsigned int pin_count;
264 };
265
266 /*
267 * Initialization, self-test and debugging-output methods:
268 */
269 extern void lockdep_init(void);
270 extern void lockdep_reset(void);
271 extern void lockdep_reset_lock(struct lockdep_map *lock);
272 extern void lockdep_free_key_range(void *start, unsigned long size);
273 extern asmlinkage void lockdep_sys_exit(void);
274
275 extern void lockdep_off(void);
276 extern void lockdep_on(void);
277
278 /*
279 * These methods are used by specific locking variants (spinlocks,
280 * rwlocks, mutexes and rwsems) to pass init/acquire/release events
281 * to lockdep:
282 */
283
284 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
285 struct lock_class_key *key, int subclass);
286
287 /*
288 * Reinitialize a lock key - for cases where there is special locking or
289 * special initialization of locks so that the validator gets the scope
290 * of dependencies wrong: they are either too broad (they need a class-split)
291 * or they are too narrow (they suffer from a false class-split):
292 */
293 #define lockdep_set_class(lock, key) \
294 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
295 #define lockdep_set_class_and_name(lock, key, name) \
296 lockdep_init_map(&(lock)->dep_map, name, key, 0)
297 #define lockdep_set_class_and_subclass(lock, key, sub) \
298 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
299 #define lockdep_set_subclass(lock, sub) \
300 lockdep_init_map(&(lock)->dep_map, #lock, \
301 (lock)->dep_map.key, sub)
302
303 #define lockdep_set_novalidate_class(lock) \
304 lockdep_set_class_and_name(lock, &__lockdep_no_validate__, #lock)
305 /*
306 * Compare locking classes
307 */
308 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
309
lockdep_match_key(struct lockdep_map * lock,struct lock_class_key * key)310 static inline int lockdep_match_key(struct lockdep_map *lock,
311 struct lock_class_key *key)
312 {
313 return lock->key == key;
314 }
315
316 /*
317 * Acquire a lock.
318 *
319 * Values for "read":
320 *
321 * 0: exclusive (write) acquire
322 * 1: read-acquire (no recursion allowed)
323 * 2: read-acquire with same-instance recursion allowed
324 *
325 * Values for check:
326 *
327 * 0: simple checks (freeing, held-at-exit-time, etc.)
328 * 1: full validation
329 */
330 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
331 int trylock, int read, int check,
332 struct lockdep_map *nest_lock, unsigned long ip);
333
334 extern void lock_release(struct lockdep_map *lock, int nested,
335 unsigned long ip);
336
337 /*
338 * Same "read" as for lock_acquire(), except -1 means any.
339 */
340 extern int lock_is_held_type(const struct lockdep_map *lock, int read);
341
lock_is_held(const struct lockdep_map * lock)342 static inline int lock_is_held(const struct lockdep_map *lock)
343 {
344 return lock_is_held_type(lock, -1);
345 }
346
347 #define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
348 #define lockdep_is_held_type(lock, r) lock_is_held_type(&(lock)->dep_map, (r))
349
350 extern void lock_set_class(struct lockdep_map *lock, const char *name,
351 struct lock_class_key *key, unsigned int subclass,
352 unsigned long ip);
353
lock_set_subclass(struct lockdep_map * lock,unsigned int subclass,unsigned long ip)354 static inline void lock_set_subclass(struct lockdep_map *lock,
355 unsigned int subclass, unsigned long ip)
356 {
357 lock_set_class(lock, lock->name, lock->key, subclass, ip);
358 }
359
360 extern void lock_downgrade(struct lockdep_map *lock, unsigned long ip);
361
362 struct pin_cookie { unsigned int val; };
363
364 #define NIL_COOKIE (struct pin_cookie){ .val = 0U, }
365
366 extern struct pin_cookie lock_pin_lock(struct lockdep_map *lock);
367 extern void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie);
368 extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
369
370 #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
371
372 #define lockdep_assert_held(l) do { \
373 WARN_ON(debug_locks && !lockdep_is_held(l)); \
374 } while (0)
375
376 #define lockdep_assert_held_exclusive(l) do { \
377 WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
378 } while (0)
379
380 #define lockdep_assert_held_read(l) do { \
381 WARN_ON(debug_locks && !lockdep_is_held_type(l, 1)); \
382 } while (0)
383
384 #define lockdep_assert_held_once(l) do { \
385 WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
386 } while (0)
387
388 #define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
389
390 #define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map)
391 #define lockdep_repin_lock(l,c) lock_repin_lock(&(l)->dep_map, (c))
392 #define lockdep_unpin_lock(l,c) lock_unpin_lock(&(l)->dep_map, (c))
393
394 #else /* !CONFIG_LOCKDEP */
395
lockdep_off(void)396 static inline void lockdep_off(void)
397 {
398 }
399
lockdep_on(void)400 static inline void lockdep_on(void)
401 {
402 }
403
404 # define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
405 # define lock_release(l, n, i) do { } while (0)
406 # define lock_downgrade(l, i) do { } while (0)
407 # define lock_set_class(l, n, k, s, i) do { } while (0)
408 # define lock_set_subclass(l, s, i) do { } while (0)
409 # define lockdep_init() do { } while (0)
410 # define lockdep_init_map(lock, name, key, sub) \
411 do { (void)(name); (void)(key); } while (0)
412 # define lockdep_set_class(lock, key) do { (void)(key); } while (0)
413 # define lockdep_set_class_and_name(lock, key, name) \
414 do { (void)(key); (void)(name); } while (0)
415 #define lockdep_set_class_and_subclass(lock, key, sub) \
416 do { (void)(key); } while (0)
417 #define lockdep_set_subclass(lock, sub) do { } while (0)
418
419 #define lockdep_set_novalidate_class(lock) do { } while (0)
420
421 /*
422 * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
423 * case since the result is not well defined and the caller should rather
424 * #ifdef the call himself.
425 */
426
427 # define lockdep_reset() do { debug_locks = 1; } while (0)
428 # define lockdep_free_key_range(start, size) do { } while (0)
429 # define lockdep_sys_exit() do { } while (0)
430 /*
431 * The class key takes no space if lockdep is disabled:
432 */
433 struct lock_class_key { };
434
435 /*
436 * The lockdep_map takes no space if lockdep is disabled:
437 */
438 struct lockdep_map { };
439
440 #define lockdep_depth(tsk) (0)
441
442 #define lockdep_is_held_type(l, r) (1)
443
444 #define lockdep_assert_held(l) do { (void)(l); } while (0)
445 #define lockdep_assert_held_exclusive(l) do { (void)(l); } while (0)
446 #define lockdep_assert_held_read(l) do { (void)(l); } while (0)
447 #define lockdep_assert_held_once(l) do { (void)(l); } while (0)
448
449 #define lockdep_recursing(tsk) (0)
450
451 struct pin_cookie { };
452
453 #define NIL_COOKIE (struct pin_cookie){ }
454
455 #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; })
456 #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0)
457 #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0)
458
459 #endif /* !LOCKDEP */
460
461 enum xhlock_context_t {
462 XHLOCK_HARD,
463 XHLOCK_SOFT,
464 XHLOCK_CTX_NR,
465 };
466
467 #define lockdep_init_map_crosslock(m, n, k, s) do {} while (0)
468 /*
469 * To initialize a lockdep_map statically use this macro.
470 * Note that _name must not be NULL.
471 */
472 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
473 { .name = (_name), .key = (void *)(_key), }
474
lockdep_invariant_state(bool force)475 static inline void lockdep_invariant_state(bool force) {}
lockdep_init_task(struct task_struct * task)476 static inline void lockdep_init_task(struct task_struct *task) {}
lockdep_free_task(struct task_struct * task)477 static inline void lockdep_free_task(struct task_struct *task) {}
478
479 #ifdef CONFIG_LOCK_STAT
480
481 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
482 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
483
484 #define LOCK_CONTENDED(_lock, try, lock) \
485 do { \
486 if (!try(_lock)) { \
487 lock_contended(&(_lock)->dep_map, _RET_IP_); \
488 lock(_lock); \
489 } \
490 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
491 } while (0)
492
493 #define LOCK_CONTENDED_RETURN(_lock, try, lock) \
494 ({ \
495 int ____err = 0; \
496 if (!try(_lock)) { \
497 lock_contended(&(_lock)->dep_map, _RET_IP_); \
498 ____err = lock(_lock); \
499 } \
500 if (!____err) \
501 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
502 ____err; \
503 })
504
505 #else /* CONFIG_LOCK_STAT */
506
507 #define lock_contended(lockdep_map, ip) do {} while (0)
508 #define lock_acquired(lockdep_map, ip) do {} while (0)
509
510 #define LOCK_CONTENDED(_lock, try, lock) \
511 lock(_lock)
512
513 #define LOCK_CONTENDED_RETURN(_lock, try, lock) \
514 lock(_lock)
515
516 #endif /* CONFIG_LOCK_STAT */
517
518 #ifdef CONFIG_LOCKDEP
519
520 /*
521 * On lockdep we dont want the hand-coded irq-enable of
522 * _raw_*_lock_flags() code, because lockdep assumes
523 * that interrupts are not re-enabled during lock-acquire:
524 */
525 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
526 LOCK_CONTENDED((_lock), (try), (lock))
527
528 #else /* CONFIG_LOCKDEP */
529
530 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
531 lockfl((_lock), (flags))
532
533 #endif /* CONFIG_LOCKDEP */
534
535 #ifdef CONFIG_PROVE_LOCKING
536 extern void print_irqtrace_events(struct task_struct *curr);
537 #else
print_irqtrace_events(struct task_struct * curr)538 static inline void print_irqtrace_events(struct task_struct *curr)
539 {
540 }
541 #endif
542
543 /*
544 * For trivial one-depth nesting of a lock-class, the following
545 * global define can be used. (Subsystems with multiple levels
546 * of nesting should define their own lock-nesting subclasses.)
547 */
548 #define SINGLE_DEPTH_NESTING 1
549
550 /*
551 * Map the dependency ops to NOP or to real lockdep ops, depending
552 * on the per lock-class debug mode:
553 */
554
555 #define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
556 #define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i)
557 #define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i)
558
559 #define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
560 #define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
561 #define spin_release(l, n, i) lock_release(l, n, i)
562
563 #define rwlock_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
564 #define rwlock_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
565 #define rwlock_release(l, n, i) lock_release(l, n, i)
566
567 #define seqcount_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
568 #define seqcount_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
569 #define seqcount_release(l, n, i) lock_release(l, n, i)
570
571 #define mutex_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
572 #define mutex_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
573 #define mutex_release(l, n, i) lock_release(l, n, i)
574
575 #define rwsem_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
576 #define rwsem_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
577 #define rwsem_acquire_read(l, s, t, i) lock_acquire_shared(l, s, t, NULL, i)
578 #define rwsem_release(l, n, i) lock_release(l, n, i)
579
580 #define lock_map_acquire(l) lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
581 #define lock_map_acquire_read(l) lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
582 #define lock_map_acquire_tryread(l) lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_)
583 #define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
584
585 #ifdef CONFIG_PROVE_LOCKING
586 # define might_lock(lock) \
587 do { \
588 typecheck(struct lockdep_map *, &(lock)->dep_map); \
589 lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, NULL, _THIS_IP_); \
590 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
591 } while (0)
592 # define might_lock_read(lock) \
593 do { \
594 typecheck(struct lockdep_map *, &(lock)->dep_map); \
595 lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_); \
596 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
597 } while (0)
598
599 #define lockdep_assert_irqs_enabled() do { \
600 WARN_ONCE(debug_locks && !current->lockdep_recursion && \
601 !current->hardirqs_enabled, \
602 "IRQs not enabled as expected\n"); \
603 } while (0)
604
605 #define lockdep_assert_irqs_disabled() do { \
606 WARN_ONCE(debug_locks && !current->lockdep_recursion && \
607 current->hardirqs_enabled, \
608 "IRQs not disabled as expected\n"); \
609 } while (0)
610
611 #else
612 # define might_lock(lock) do { } while (0)
613 # define might_lock_read(lock) do { } while (0)
614 # define lockdep_assert_irqs_enabled() do { } while (0)
615 # define lockdep_assert_irqs_disabled() do { } while (0)
616 #endif
617
618 #ifdef CONFIG_LOCKDEP
619 void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
620 #else
621 static inline void
lockdep_rcu_suspicious(const char * file,const int line,const char * s)622 lockdep_rcu_suspicious(const char *file, const int line, const char *s)
623 {
624 }
625 #endif
626
627 #endif /* __LINUX_LOCKDEP_H */
628