1 #define _GNU_SOURCE
2 #include <pthread.h>
3 #include <stdio.h>
4 #include <dlfcn.h>
5 #include <stdlib.h>
6 #include <sysexits.h>
7 #include "include/liblockdep/mutex.h"
8 #include "../../include/linux/rbtree.h"
9
10 /**
11 * struct lock_lookup - liblockdep's view of a single unique lock
12 * @orig: pointer to the original pthread lock, used for lookups
13 * @dep_map: lockdep's dep_map structure
14 * @key: lockdep's key structure
15 * @node: rb-tree node used to store the lock in a global tree
16 * @name: a unique name for the lock
17 */
18 struct lock_lookup {
19 void *orig; /* Original pthread lock, used for lookups */
20 struct lockdep_map dep_map; /* Since all locks are dynamic, we need
21 * a dep_map and a key for each lock */
22 /*
23 * Wait, there's no support for key classes? Yup :(
24 * Most big projects wrap the pthread api with their own calls to
25 * be compatible with different locking methods. This means that
26 * "classes" will be brokes since the function that creates all
27 * locks will point to a generic locking function instead of the
28 * actual code that wants to do the locking.
29 */
30 struct lock_class_key key;
31 struct rb_node node;
32 #define LIBLOCKDEP_MAX_LOCK_NAME 22
33 char name[LIBLOCKDEP_MAX_LOCK_NAME];
34 };
35
36 /* This is where we store our locks */
37 static struct rb_root locks = RB_ROOT;
38 static pthread_rwlock_t locks_rwlock = PTHREAD_RWLOCK_INITIALIZER;
39
40 /* pthread mutex API */
41
42 #ifdef __GLIBC__
43 extern int __pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);
44 extern int __pthread_mutex_lock(pthread_mutex_t *mutex);
45 extern int __pthread_mutex_trylock(pthread_mutex_t *mutex);
46 extern int __pthread_mutex_unlock(pthread_mutex_t *mutex);
47 extern int __pthread_mutex_destroy(pthread_mutex_t *mutex);
48 #else
49 #define __pthread_mutex_init NULL
50 #define __pthread_mutex_lock NULL
51 #define __pthread_mutex_trylock NULL
52 #define __pthread_mutex_unlock NULL
53 #define __pthread_mutex_destroy NULL
54 #endif
55 static int (*ll_pthread_mutex_init)(pthread_mutex_t *mutex,
56 const pthread_mutexattr_t *attr) = __pthread_mutex_init;
57 static int (*ll_pthread_mutex_lock)(pthread_mutex_t *mutex) = __pthread_mutex_lock;
58 static int (*ll_pthread_mutex_trylock)(pthread_mutex_t *mutex) = __pthread_mutex_trylock;
59 static int (*ll_pthread_mutex_unlock)(pthread_mutex_t *mutex) = __pthread_mutex_unlock;
60 static int (*ll_pthread_mutex_destroy)(pthread_mutex_t *mutex) = __pthread_mutex_destroy;
61
62 /* pthread rwlock API */
63
64 #ifdef __GLIBC__
65 extern int __pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr);
66 extern int __pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
67 extern int __pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
68 extern int __pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
69 extern int __pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);
70 extern int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock);
71 extern int __pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
72 #else
73 #define __pthread_rwlock_init NULL
74 #define __pthread_rwlock_destroy NULL
75 #define __pthread_rwlock_wrlock NULL
76 #define __pthread_rwlock_trywrlock NULL
77 #define __pthread_rwlock_rdlock NULL
78 #define __pthread_rwlock_tryrdlock NULL
79 #define __pthread_rwlock_unlock NULL
80 #endif
81
82 static int (*ll_pthread_rwlock_init)(pthread_rwlock_t *rwlock,
83 const pthread_rwlockattr_t *attr) = __pthread_rwlock_init;
84 static int (*ll_pthread_rwlock_destroy)(pthread_rwlock_t *rwlock) = __pthread_rwlock_destroy;
85 static int (*ll_pthread_rwlock_rdlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_rdlock;
86 static int (*ll_pthread_rwlock_tryrdlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_tryrdlock;
87 static int (*ll_pthread_rwlock_trywrlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_trywrlock;
88 static int (*ll_pthread_rwlock_wrlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_wrlock;
89 static int (*ll_pthread_rwlock_unlock)(pthread_rwlock_t *rwlock) = __pthread_rwlock_unlock;
90
91 enum { none, prepare, done, } __init_state;
92 static void init_preload(void);
93 static void try_init_preload(void)
94 {
95 if (__init_state != done)
96 init_preload();
97 }
98
99 static struct rb_node **__get_lock_node(void *lock, struct rb_node **parent)
100 {
101 struct rb_node **node = &locks.rb_node;
102 struct lock_lookup *l;
103
104 *parent = NULL;
105
106 while (*node) {
107 l = rb_entry(*node, struct lock_lookup, node);
108
109 *parent = *node;
110 if (lock < l->orig)
111 node = &l->node.rb_left;
112 else if (lock > l->orig)
113 node = &l->node.rb_right;
114 else
115 return node;
116 }
117
118 return node;
119 }
120
121 #ifndef LIBLOCKDEP_STATIC_ENTRIES
122 #define LIBLOCKDEP_STATIC_ENTRIES 1024
123 #endif
124
125 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
126
127 static struct lock_lookup __locks[LIBLOCKDEP_STATIC_ENTRIES];
128 static int __locks_nr;
129
130 static inline bool is_static_lock(struct lock_lookup *lock)
131 {
132 return lock >= __locks && lock < __locks + ARRAY_SIZE(__locks);
133 }
134
135 static struct lock_lookup *alloc_lock(void)
136 {
137 if (__init_state != done) {
138 /*
139 * Some programs attempt to initialize and use locks in their
140 * allocation path. This means that a call to malloc() would
141 * result in locks being initialized and locked.
142 *
143 * Why is it an issue for us? dlsym() below will try allocating
144 * to give us the original function. Since this allocation will
145 * result in a locking operations, we have to let pthread deal
146 * with it, but we can't! we don't have the pointer to the
147 * original API since we're inside dlsym() trying to get it
148 */
149
150 int idx = __locks_nr++;
151 if (idx >= ARRAY_SIZE(__locks)) {
152 fprintf(stderr,
153 "LOCKDEP error: insufficient LIBLOCKDEP_STATIC_ENTRIES\n");
154 exit(EX_UNAVAILABLE);
155 }
156 return __locks + idx;
157 }
158
159 return malloc(sizeof(struct lock_lookup));
160 }
161
162 static inline void free_lock(struct lock_lookup *lock)
163 {
164 if (likely(!is_static_lock(lock)))
165 free(lock);
166 }
167
168 /**
169 * __get_lock - find or create a lock instance
170 * @lock: pointer to a pthread lock function
171 *
172 * Try to find an existing lock in the rbtree using the provided pointer. If
173 * one wasn't found - create it.
174 */
175 static struct lock_lookup *__get_lock(void *lock)
176 {
177 struct rb_node **node, *parent;
178 struct lock_lookup *l;
179
180 ll_pthread_rwlock_rdlock(&locks_rwlock);
181 node = __get_lock_node(lock, &parent);
182 ll_pthread_rwlock_unlock(&locks_rwlock);
183 if (*node) {
184 return rb_entry(*node, struct lock_lookup, node);
185 }
186
187 /* We didn't find the lock, let's create it */
188 l = alloc_lock();
189 if (l == NULL)
190 return NULL;
191
192 l->orig = lock;
193 /*
194 * Currently the name of the lock is the ptr value of the pthread lock,
195 * while not optimal, it makes debugging a bit easier.
196 *
197 * TODO: Get the real name of the lock using libdwarf
198 */
199 sprintf(l->name, "%p", lock);
200 lockdep_init_map(&l->dep_map, l->name, &l->key, 0);
201
202 ll_pthread_rwlock_wrlock(&locks_rwlock);
203 /* This might have changed since the last time we fetched it */
204 node = __get_lock_node(lock, &parent);
205 rb_link_node(&l->node, parent, node);
206 rb_insert_color(&l->node, &locks);
207 ll_pthread_rwlock_unlock(&locks_rwlock);
208
209 return l;
210 }
211
212 static void __del_lock(struct lock_lookup *lock)
213 {
214 ll_pthread_rwlock_wrlock(&locks_rwlock);
215 rb_erase(&lock->node, &locks);
216 ll_pthread_rwlock_unlock(&locks_rwlock);
217 free_lock(lock);
218 }
219
220 int pthread_mutex_init(pthread_mutex_t *mutex,
221 const pthread_mutexattr_t *attr)
222 {
223 int r;
224
225 /*
226 * We keep trying to init our preload module because there might be
227 * code in init sections that tries to touch locks before we are
228 * initialized, in that case we'll need to manually call preload
229 * to get us going.
230 *
231 * Funny enough, kernel's lockdep had the same issue, and used
232 * (almost) the same solution. See look_up_lock_class() in
233 * kernel/locking/lockdep.c for details.
234 */
235 try_init_preload();
236
237 r = ll_pthread_mutex_init(mutex, attr);
238 if (r == 0)
239 /*
240 * We do a dummy initialization here so that lockdep could
241 * warn us if something fishy is going on - such as
242 * initializing a held lock.
243 */
244 __get_lock(mutex);
245
246 return r;
247 }
248
249 int pthread_mutex_lock(pthread_mutex_t *mutex)
250 {
251 int r;
252
253 try_init_preload();
254
255 lock_acquire(&__get_lock(mutex)->dep_map, 0, 0, 0, 1, NULL,
256 (unsigned long)_RET_IP_);
257 /*
258 * Here's the thing with pthread mutexes: unlike the kernel variant,
259 * they can fail.
260 *
261 * This means that the behaviour here is a bit different from what's
262 * going on in the kernel: there we just tell lockdep that we took the
263 * lock before actually taking it, but here we must deal with the case
264 * that locking failed.
265 *
266 * To do that we'll "release" the lock if locking failed - this way
267 * we'll get lockdep doing the correct checks when we try to take
268 * the lock, and if that fails - we'll be back to the correct
269 * state by releasing it.
270 */
271 r = ll_pthread_mutex_lock(mutex);
272 if (r)
273 lock_release(&__get_lock(mutex)->dep_map, 0, (unsigned long)_RET_IP_);
274
275 return r;
276 }
277
278 int pthread_mutex_trylock(pthread_mutex_t *mutex)
279 {
280 int r;
281
282 try_init_preload();
283
284 lock_acquire(&__get_lock(mutex)->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_);
285 r = ll_pthread_mutex_trylock(mutex);
286 if (r)
287 lock_release(&__get_lock(mutex)->dep_map, 0, (unsigned long)_RET_IP_);
288
289 return r;
290 }
291
292 int pthread_mutex_unlock(pthread_mutex_t *mutex)
293 {
294 int r;
295
296 try_init_preload();
297
298 lock_release(&__get_lock(mutex)->dep_map, 0, (unsigned long)_RET_IP_);
299 /*
300 * Just like taking a lock, only in reverse!
301 *
302 * If we fail releasing the lock, tell lockdep we're holding it again.
303 */
304 r = ll_pthread_mutex_unlock(mutex);
305 if (r)
306 lock_acquire(&__get_lock(mutex)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_);
307
308 return r;
309 }
310
311 int pthread_mutex_destroy(pthread_mutex_t *mutex)
312 {
313 try_init_preload();
314
315 /*
316 * Let's see if we're releasing a lock that's held.
317 *
318 * TODO: Hook into free() and add that check there as well.
319 */
320 debug_check_no_locks_freed(mutex, sizeof(*mutex));
321 __del_lock(__get_lock(mutex));
322 return ll_pthread_mutex_destroy(mutex);
323 }
324
325 /* This is the rwlock part, very similar to what happened with mutex above */
326 int pthread_rwlock_init(pthread_rwlock_t *rwlock,
327 const pthread_rwlockattr_t *attr)
328 {
329 int r;
330
331 try_init_preload();
332
333 r = ll_pthread_rwlock_init(rwlock, attr);
334 if (r == 0)
335 __get_lock(rwlock);
336
337 return r;
338 }
339
340 int pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
341 {
342 try_init_preload();
343
344 debug_check_no_locks_freed(rwlock, sizeof(*rwlock));
345 __del_lock(__get_lock(rwlock));
346 return ll_pthread_rwlock_destroy(rwlock);
347 }
348
349 int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
350 {
351 int r;
352
353 init_preload();
354
355 lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 2, 1, NULL, (unsigned long)_RET_IP_);
356 r = ll_pthread_rwlock_rdlock(rwlock);
357 if (r)
358 lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
359
360 return r;
361 }
362
363 int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
364 {
365 int r;
366
367 init_preload();
368
369 lock_acquire(&__get_lock(rwlock)->dep_map, 0, 1, 2, 1, NULL, (unsigned long)_RET_IP_);
370 r = ll_pthread_rwlock_tryrdlock(rwlock);
371 if (r)
372 lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
373
374 return r;
375 }
376
377 int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock)
378 {
379 int r;
380
381 init_preload();
382
383 lock_acquire(&__get_lock(rwlock)->dep_map, 0, 1, 0, 1, NULL, (unsigned long)_RET_IP_);
384 r = ll_pthread_rwlock_trywrlock(rwlock);
385 if (r)
386 lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
387
388 return r;
389 }
390
391 int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
392 {
393 int r;
394
395 init_preload();
396
397 lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_);
398 r = ll_pthread_rwlock_wrlock(rwlock);
399 if (r)
400 lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
401
402 return r;
403 }
404
405 int pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
406 {
407 int r;
408
409 init_preload();
410
411 lock_release(&__get_lock(rwlock)->dep_map, 0, (unsigned long)_RET_IP_);
412 r = ll_pthread_rwlock_unlock(rwlock);
413 if (r)
414 lock_acquire(&__get_lock(rwlock)->dep_map, 0, 0, 0, 1, NULL, (unsigned long)_RET_IP_);
415
416 return r;
417 }
418
419 __attribute__((constructor)) static void init_preload(void)
420 {
421 if (__init_state == done)
422 return;
423
424 #ifndef __GLIBC__
425 __init_state = prepare;
426
427 ll_pthread_mutex_init = dlsym(RTLD_NEXT, "pthread_mutex_init");
428 ll_pthread_mutex_lock = dlsym(RTLD_NEXT, "pthread_mutex_lock");
429 ll_pthread_mutex_trylock = dlsym(RTLD_NEXT, "pthread_mutex_trylock");
430 ll_pthread_mutex_unlock = dlsym(RTLD_NEXT, "pthread_mutex_unlock");
431 ll_pthread_mutex_destroy = dlsym(RTLD_NEXT, "pthread_mutex_destroy");
432
433 ll_pthread_rwlock_init = dlsym(RTLD_NEXT, "pthread_rwlock_init");
434 ll_pthread_rwlock_destroy = dlsym(RTLD_NEXT, "pthread_rwlock_destroy");
435 ll_pthread_rwlock_rdlock = dlsym(RTLD_NEXT, "pthread_rwlock_rdlock");
436 ll_pthread_rwlock_tryrdlock = dlsym(RTLD_NEXT, "pthread_rwlock_tryrdlock");
437 ll_pthread_rwlock_wrlock = dlsym(RTLD_NEXT, "pthread_rwlock_wrlock");
438 ll_pthread_rwlock_trywrlock = dlsym(RTLD_NEXT, "pthread_rwlock_trywrlock");
439 ll_pthread_rwlock_unlock = dlsym(RTLD_NEXT, "pthread_rwlock_unlock");
440 #endif
441
442 __init_state = done;
443 }
444
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