2 * Copyright (C) 2008-2011 Mathieu Desnoyers
3 * Copyright (C) 2009 Pierre-Marc Fournier
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation;
8 * version 2.1 of the License.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 * Ported to userspace by Pierre-Marc Fournier.
28 #include <urcu/arch.h>
29 #include <lttng/urcu/urcu-ust.h>
30 #include <urcu/hlist.h>
31 #include <urcu/uatomic.h>
32 #include <urcu/compiler.h>
33 #include <urcu/system.h>
35 #include <lttng/tracepoint.h>
36 #include <lttng/ust-abi.h> /* for LTTNG_UST_SYM_NAME_LEN */
38 #include <usterr-signal-safe.h>
41 #include "tracepoint-internal.h"
42 #include "lttng-tracer-core.h"
46 /* Test compiler support for weak symbols with hidden visibility. */
47 int __tracepoint_test_symbol1
__attribute__((weak
, visibility("hidden")));
48 void *__tracepoint_test_symbol2
__attribute__((weak
, visibility("hidden")));
51 } __tracepoint_test_symbol3
__attribute__((weak
, visibility("hidden")));
53 /* Set to 1 to enable tracepoint debug output */
54 static const int tracepoint_debug
;
55 static int initialized
;
58 * If tracepoint_destructors_state = 1, tracepoint destructors are
59 * enabled. They are disabled otherwise.
61 static int tracepoint_destructors_state
= 1;
63 static void (*new_tracepoint_cb
)(struct lttng_ust_tracepoint
*);
66 * tracepoint_mutex nests inside UST mutex.
68 * Note about interaction with fork/clone: UST does not hold the
69 * tracepoint mutex across fork/clone because it is either:
70 * - nested within UST mutex, in which case holding the UST mutex across
72 * - taken by a library constructor, which should never race with a
73 * fork/clone if the application is expected to continue running with
74 * the same memory layout (no following exec()).
76 static pthread_mutex_t tracepoint_mutex
= PTHREAD_MUTEX_INITIALIZER
;
79 * libraries that contain tracepoints (struct tracepoint_lib).
80 * Protected by tracepoint mutex.
82 static CDS_LIST_HEAD(libs
);
85 * The tracepoint mutex protects the library tracepoints, the hash table, and
87 * All calls to the tracepoint API must be protected by the tracepoint mutex,
88 * excepts calls to tracepoint_register_lib and
89 * tracepoint_unregister_lib, which take the tracepoint mutex themselves.
93 * Tracepoint hash table, containing the active tracepoints.
94 * Protected by tracepoint mutex.
96 #define TRACEPOINT_HASH_BITS 12
97 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
98 static struct cds_hlist_head tracepoint_table
[TRACEPOINT_TABLE_SIZE
];
100 static CDS_LIST_HEAD(old_probes
);
101 static int need_update
;
103 static CDS_LIST_HEAD(release_queue
);
104 static int release_queue_need_update
;
108 * It is used to to delay the free of multiple probes array until a quiescent
110 * Tracepoint entries modifications are protected by the tracepoint mutex.
112 struct tracepoint_entry
{
113 struct cds_hlist_node hlist
;
114 struct lttng_ust_tracepoint_probe
*probes
;
115 int refcount
; /* Number of times armed. 0 if disarmed. */
116 int callsite_refcount
; /* how many libs use this tracepoint */
123 struct cds_list_head list
;
124 /* Field below only used for call_rcu scheme */
125 /* struct rcu_head head; */
127 struct lttng_ust_tracepoint_probe probes
[0];
131 * Callsite hash table, containing the tracepoint call sites.
132 * Protected by tracepoint mutex.
134 #define CALLSITE_HASH_BITS 12
135 #define CALLSITE_TABLE_SIZE (1 << CALLSITE_HASH_BITS)
136 static struct cds_hlist_head callsite_table
[CALLSITE_TABLE_SIZE
];
138 struct callsite_entry
{
139 struct cds_hlist_node hlist
; /* hash table node */
140 struct cds_list_head node
; /* lib list of callsites node */
141 struct lttng_ust_tracepoint
*tp
;
142 bool tp_entry_callsite_ref
; /* Has a tp_entry took a ref on this callsite */
145 /* coverity[+alloc] */
146 static void *allocate_probes(int count
)
148 struct tp_probes
*p
=
149 zmalloc(count
* sizeof(struct lttng_ust_tracepoint_probe
)
150 + sizeof(struct tp_probes
));
151 return p
== NULL
? NULL
: p
->probes
;
154 /* coverity[+free : arg-0] */
155 static void release_probes(void *old
)
158 struct tp_probes
*tp_probes
= caa_container_of(old
,
159 struct tp_probes
, probes
[0]);
160 lttng_ust_synchronize_trace();
165 static void debug_print_probes(struct tracepoint_entry
*entry
)
169 if (!tracepoint_debug
|| !entry
->probes
)
172 for (i
= 0; entry
->probes
[i
].func
; i
++)
173 DBG("Probe %d : %p", i
, entry
->probes
[i
].func
);
177 tracepoint_entry_add_probe(struct tracepoint_entry
*entry
,
178 void (*probe
)(void), void *data
)
181 struct lttng_ust_tracepoint_probe
*old
, *new;
185 return ERR_PTR(-EINVAL
);
187 debug_print_probes(entry
);
190 /* (N -> N+1), (N != 0, 1) probes */
191 for (nr_probes
= 0; old
[nr_probes
].func
; nr_probes
++)
192 if (old
[nr_probes
].func
== probe
&&
193 old
[nr_probes
].data
== data
)
194 return ERR_PTR(-EEXIST
);
196 /* + 2 : one for new probe, one for NULL func */
197 new = allocate_probes(nr_probes
+ 2);
199 return ERR_PTR(-ENOMEM
);
202 nr_probes
* sizeof(struct lttng_ust_tracepoint_probe
));
203 new[nr_probes
].func
= probe
;
204 new[nr_probes
].data
= data
;
205 new[nr_probes
+ 1].func
= NULL
;
206 entry
->refcount
= nr_probes
+ 1;
208 debug_print_probes(entry
);
213 tracepoint_entry_remove_probe(struct tracepoint_entry
*entry
,
214 void (*probe
)(void), void *data
)
216 int nr_probes
= 0, nr_del
= 0, i
;
217 struct lttng_ust_tracepoint_probe
*old
, *new;
222 return ERR_PTR(-ENOENT
);
224 debug_print_probes(entry
);
225 /* (N -> M), (N > 1, M >= 0) probes */
227 for (nr_probes
= 0; old
[nr_probes
].func
; nr_probes
++) {
228 if (old
[nr_probes
].func
== probe
&&
229 old
[nr_probes
].data
== data
)
234 if (nr_probes
- nr_del
== 0) {
235 /* N -> 0, (N > 1) */
236 entry
->probes
= NULL
;
238 debug_print_probes(entry
);
242 /* N -> M, (N > 1, M > 0) */
244 new = allocate_probes(nr_probes
- nr_del
+ 1);
246 return ERR_PTR(-ENOMEM
);
247 for (i
= 0; old
[i
].func
; i
++)
248 if (old
[i
].func
!= probe
|| old
[i
].data
!= data
)
250 new[nr_probes
- nr_del
].func
= NULL
;
251 entry
->refcount
= nr_probes
- nr_del
;
254 debug_print_probes(entry
);
259 * Get tracepoint if the tracepoint is present in the tracepoint hash table.
260 * Must be called with tracepoint mutex held.
261 * Returns NULL if not present.
263 static struct tracepoint_entry
*get_tracepoint(const char *name
)
265 struct cds_hlist_head
*head
;
266 struct cds_hlist_node
*node
;
267 struct tracepoint_entry
*e
;
268 size_t name_len
= strlen(name
);
271 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
272 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
273 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
275 hash
= jhash(name
, name_len
, 0);
276 head
= &tracepoint_table
[hash
& (TRACEPOINT_TABLE_SIZE
- 1)];
277 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
278 if (!strncmp(name
, e
->name
, LTTNG_UST_SYM_NAME_LEN
- 1))
285 * Add the tracepoint to the tracepoint hash table. Must be called with
286 * tracepoint mutex held.
288 static struct tracepoint_entry
*add_tracepoint(const char *name
,
289 const char *signature
)
291 struct cds_hlist_head
*head
;
292 struct cds_hlist_node
*node
;
293 struct tracepoint_entry
*e
;
294 size_t name_len
= strlen(name
);
295 size_t sig_len
= strlen(signature
);
296 size_t sig_off
, name_off
;
299 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
300 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
301 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
303 hash
= jhash(name
, name_len
, 0);
304 head
= &tracepoint_table
[hash
& (TRACEPOINT_TABLE_SIZE
- 1)];
305 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
306 if (!strncmp(name
, e
->name
, LTTNG_UST_SYM_NAME_LEN
- 1)) {
307 DBG("tracepoint %s busy", name
);
308 return ERR_PTR(-EEXIST
); /* Already there */
313 * Using zmalloc here to allocate a variable length elements: name and
314 * signature. Could cause some memory fragmentation if overused.
316 name_off
= sizeof(struct tracepoint_entry
);
317 sig_off
= name_off
+ name_len
+ 1;
319 e
= zmalloc(sizeof(struct tracepoint_entry
) + name_len
+ 1 + sig_len
+ 1);
321 return ERR_PTR(-ENOMEM
);
322 e
->name
= (char *) e
+ name_off
;
323 memcpy(e
->name
, name
, name_len
+ 1);
324 e
->name
[name_len
] = '\0';
326 e
->signature
= (char *) e
+ sig_off
;
327 memcpy(e
->signature
, signature
, sig_len
+ 1);
328 e
->signature
[sig_len
] = '\0';
332 e
->callsite_refcount
= 0;
334 cds_hlist_add_head(&e
->hlist
, head
);
339 * Remove the tracepoint from the tracepoint hash table. Must be called with
340 * tracepoint mutex held.
342 static void remove_tracepoint(struct tracepoint_entry
*e
)
344 cds_hlist_del(&e
->hlist
);
349 * Sets the probe callback corresponding to one tracepoint.
351 static void set_tracepoint(struct tracepoint_entry
**entry
,
352 struct lttng_ust_tracepoint
*elem
, int active
)
354 WARN_ON(strncmp((*entry
)->name
, elem
->name
, LTTNG_UST_SYM_NAME_LEN
- 1) != 0);
356 * Check that signatures match before connecting a probe to a
357 * tracepoint. Warn the user if they don't.
359 if (strcmp(elem
->signature
, (*entry
)->signature
) != 0) {
360 static int warned
= 0;
362 /* Only print once, don't flood console. */
364 WARN("Tracepoint signature mismatch, not enabling one or more tracepoints. Ensure that the tracepoint probes prototypes match the application.");
365 WARN("Tracepoint \"%s\" signatures: call: \"%s\" vs probe: \"%s\".",
366 elem
->name
, elem
->signature
, (*entry
)->signature
);
369 /* Don't accept connecting non-matching signatures. */
374 * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new
375 * probe callbacks array is consistent before setting a pointer to it.
376 * This array is referenced by __DO_TRACE from
377 * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
380 lttng_ust_rcu_assign_pointer(elem
->probes
, (*entry
)->probes
);
381 CMM_STORE_SHARED(elem
->state
, active
);
385 * Disable a tracepoint and its probe callback.
386 * Note: only waiting an RCU period after setting elem->call to the empty
387 * function insures that the original callback is not used anymore. This insured
388 * by preempt_disable around the call site.
390 static void disable_tracepoint(struct lttng_ust_tracepoint
*elem
)
392 CMM_STORE_SHARED(elem
->state
, 0);
393 lttng_ust_rcu_assign_pointer(elem
->probes
, NULL
);
397 * Add the callsite to the callsite hash table. Must be called with
398 * tracepoint mutex held.
400 static void add_callsite(struct tracepoint_lib
* lib
, struct lttng_ust_tracepoint
*tp
)
402 struct cds_hlist_head
*head
;
403 struct callsite_entry
*e
;
404 const char *name
= tp
->name
;
405 size_t name_len
= strlen(name
);
407 struct tracepoint_entry
*tp_entry
;
409 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
410 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
411 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
413 hash
= jhash(name
, name_len
, 0);
414 head
= &callsite_table
[hash
& (CALLSITE_TABLE_SIZE
- 1)];
415 e
= zmalloc(sizeof(struct callsite_entry
));
417 PERROR("Unable to add callsite for tracepoint \"%s\"", name
);
420 cds_hlist_add_head(&e
->hlist
, head
);
422 cds_list_add(&e
->node
, &lib
->callsites
);
424 tp_entry
= get_tracepoint(name
);
427 tp_entry
->callsite_refcount
++;
428 e
->tp_entry_callsite_ref
= true;
432 * Remove the callsite from the callsite hash table and from lib
433 * callsite list. Must be called with tracepoint mutex held.
435 static void remove_callsite(struct callsite_entry
*e
)
437 struct tracepoint_entry
*tp_entry
;
439 tp_entry
= get_tracepoint(e
->tp
->name
);
441 if (e
->tp_entry_callsite_ref
)
442 tp_entry
->callsite_refcount
--;
443 if (tp_entry
->callsite_refcount
== 0)
444 disable_tracepoint(e
->tp
);
446 cds_hlist_del(&e
->hlist
);
447 cds_list_del(&e
->node
);
452 * Enable/disable all callsites based on the state of a specific
454 * Must be called with tracepoint mutex held.
456 static void tracepoint_sync_callsites(const char *name
)
458 struct cds_hlist_head
*head
;
459 struct cds_hlist_node
*node
;
460 struct callsite_entry
*e
;
461 size_t name_len
= strlen(name
);
463 struct tracepoint_entry
*tp_entry
;
465 tp_entry
= get_tracepoint(name
);
466 if (name_len
> LTTNG_UST_SYM_NAME_LEN
- 1) {
467 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name
, LTTNG_UST_SYM_NAME_LEN
- 1);
468 name_len
= LTTNG_UST_SYM_NAME_LEN
- 1;
470 hash
= jhash(name
, name_len
, 0);
471 head
= &callsite_table
[hash
& (CALLSITE_TABLE_SIZE
- 1)];
472 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
473 struct lttng_ust_tracepoint
*tp
= e
->tp
;
475 if (strncmp(name
, tp
->name
, LTTNG_UST_SYM_NAME_LEN
- 1))
478 if (!e
->tp_entry_callsite_ref
) {
479 tp_entry
->callsite_refcount
++;
480 e
->tp_entry_callsite_ref
= true;
482 set_tracepoint(&tp_entry
, tp
,
483 !!tp_entry
->refcount
);
485 disable_tracepoint(tp
);
486 e
->tp_entry_callsite_ref
= false;
492 * tracepoint_update_probe_range - Update a probe range
493 * @begin: beginning of the range
494 * @end: end of the range
496 * Updates the probe callback corresponding to a range of tracepoints.
499 void tracepoint_update_probe_range(struct lttng_ust_tracepoint
* const *begin
,
500 struct lttng_ust_tracepoint
* const *end
)
502 struct lttng_ust_tracepoint
* const *iter
;
503 struct tracepoint_entry
*mark_entry
;
505 for (iter
= begin
; iter
< end
; iter
++) {
507 continue; /* skip dummy */
508 if (!(*iter
)->name
) {
509 disable_tracepoint(*iter
);
512 mark_entry
= get_tracepoint((*iter
)->name
);
514 set_tracepoint(&mark_entry
, *iter
,
515 !!mark_entry
->refcount
);
517 disable_tracepoint(*iter
);
522 static void lib_update_tracepoints(struct tracepoint_lib
*lib
)
524 tracepoint_update_probe_range(lib
->tracepoints_start
,
525 lib
->tracepoints_start
+ lib
->tracepoints_count
);
528 static void lib_register_callsites(struct tracepoint_lib
*lib
)
530 struct lttng_ust_tracepoint
* const *begin
;
531 struct lttng_ust_tracepoint
* const *end
;
532 struct lttng_ust_tracepoint
* const *iter
;
534 begin
= lib
->tracepoints_start
;
535 end
= lib
->tracepoints_start
+ lib
->tracepoints_count
;
537 for (iter
= begin
; iter
< end
; iter
++) {
539 continue; /* skip dummy */
540 if (!(*iter
)->name
) {
543 add_callsite(lib
, *iter
);
547 static void lib_unregister_callsites(struct tracepoint_lib
*lib
)
549 struct callsite_entry
*callsite
, *tmp
;
551 cds_list_for_each_entry_safe(callsite
, tmp
, &lib
->callsites
, node
)
552 remove_callsite(callsite
);
556 * Update probes, removing the faulty probes.
558 static void tracepoint_update_probes(void)
560 struct tracepoint_lib
*lib
;
562 /* tracepoints registered from libraries and executable. */
563 cds_list_for_each_entry(lib
, &libs
, list
)
564 lib_update_tracepoints(lib
);
567 static struct lttng_ust_tracepoint_probe
*
568 tracepoint_add_probe(const char *name
, void (*probe
)(void), void *data
,
569 const char *signature
)
571 struct tracepoint_entry
*entry
;
572 struct lttng_ust_tracepoint_probe
*old
;
574 entry
= get_tracepoint(name
);
576 if (strcmp(entry
->signature
, signature
) != 0) {
577 ERR("Tracepoint and probe signature do not match.");
578 return ERR_PTR(-EINVAL
);
581 entry
= add_tracepoint(name
, signature
);
583 return (struct lttng_ust_tracepoint_probe
*)entry
;
585 old
= tracepoint_entry_add_probe(entry
, probe
, data
);
586 if (IS_ERR(old
) && !entry
->refcount
)
587 remove_tracepoint(entry
);
591 static void tracepoint_release_queue_add_old_probes(void *old
)
593 release_queue_need_update
= 1;
595 struct tp_probes
*tp_probes
= caa_container_of(old
,
596 struct tp_probes
, probes
[0]);
597 cds_list_add(&tp_probes
->u
.list
, &release_queue
);
602 * __tracepoint_probe_register - Connect a probe to a tracepoint
603 * @name: tracepoint name
604 * @probe: probe handler
606 * Returns 0 if ok, error value on error.
607 * The probe address must at least be aligned on the architecture pointer size.
608 * Called with the tracepoint mutex held.
610 int __tracepoint_probe_register(const char *name
, void (*probe
)(void),
611 void *data
, const char *signature
)
616 DBG("Registering probe to tracepoint %s", name
);
618 pthread_mutex_lock(&tracepoint_mutex
);
619 old
= tracepoint_add_probe(name
, probe
, data
, signature
);
625 tracepoint_sync_callsites(name
);
628 pthread_mutex_unlock(&tracepoint_mutex
);
633 * Caller needs to invoke __tracepoint_probe_release_queue() after
634 * calling __tracepoint_probe_register_queue_release() one or multiple
635 * times to ensure it does not leak memory.
637 int __tracepoint_probe_register_queue_release(const char *name
,
638 void (*probe
)(void), void *data
, const char *signature
)
643 DBG("Registering probe to tracepoint %s. Queuing release.", name
);
645 pthread_mutex_lock(&tracepoint_mutex
);
646 old
= tracepoint_add_probe(name
, probe
, data
, signature
);
652 tracepoint_sync_callsites(name
);
653 tracepoint_release_queue_add_old_probes(old
);
655 pthread_mutex_unlock(&tracepoint_mutex
);
659 static void *tracepoint_remove_probe(const char *name
, void (*probe
)(void),
662 struct tracepoint_entry
*entry
;
665 entry
= get_tracepoint(name
);
667 return ERR_PTR(-ENOENT
);
668 old
= tracepoint_entry_remove_probe(entry
, probe
, data
);
671 if (!entry
->refcount
)
672 remove_tracepoint(entry
);
677 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
678 * @name: tracepoint name
679 * @probe: probe function pointer
680 * @probe: probe data pointer
682 int __tracepoint_probe_unregister(const char *name
, void (*probe
)(void),
688 DBG("Un-registering probe from tracepoint %s", name
);
690 pthread_mutex_lock(&tracepoint_mutex
);
691 old
= tracepoint_remove_probe(name
, probe
, data
);
696 tracepoint_sync_callsites(name
);
699 pthread_mutex_unlock(&tracepoint_mutex
);
704 * Caller needs to invoke __tracepoint_probe_release_queue() after
705 * calling __tracepoint_probe_unregister_queue_release() one or multiple
706 * times to ensure it does not leak memory.
708 int __tracepoint_probe_unregister_queue_release(const char *name
,
709 void (*probe
)(void), void *data
)
714 DBG("Un-registering probe from tracepoint %s. Queuing release.", name
);
716 pthread_mutex_lock(&tracepoint_mutex
);
717 old
= tracepoint_remove_probe(name
, probe
, data
);
722 tracepoint_sync_callsites(name
);
723 tracepoint_release_queue_add_old_probes(old
);
725 pthread_mutex_unlock(&tracepoint_mutex
);
729 void __tracepoint_probe_prune_release_queue(void)
731 CDS_LIST_HEAD(release_probes
);
732 struct tp_probes
*pos
, *next
;
734 DBG("Release queue of unregistered tracepoint probes.");
736 pthread_mutex_lock(&tracepoint_mutex
);
737 if (!release_queue_need_update
)
739 if (!cds_list_empty(&release_queue
))
740 cds_list_replace_init(&release_queue
, &release_probes
);
741 release_queue_need_update
= 0;
743 /* Wait for grace period between all sync_callsites and free. */
744 lttng_ust_synchronize_trace();
746 cds_list_for_each_entry_safe(pos
, next
, &release_probes
, u
.list
) {
747 cds_list_del(&pos
->u
.list
);
751 pthread_mutex_unlock(&tracepoint_mutex
);
754 static void tracepoint_add_old_probes(void *old
)
758 struct tp_probes
*tp_probes
= caa_container_of(old
,
759 struct tp_probes
, probes
[0]);
760 cds_list_add(&tp_probes
->u
.list
, &old_probes
);
765 * tracepoint_probe_register_noupdate - register a probe but not connect
766 * @name: tracepoint name
767 * @probe: probe handler
769 * caller must call tracepoint_probe_update_all()
771 int tracepoint_probe_register_noupdate(const char *name
, void (*probe
)(void),
772 void *data
, const char *signature
)
777 pthread_mutex_lock(&tracepoint_mutex
);
778 old
= tracepoint_add_probe(name
, probe
, data
, signature
);
783 tracepoint_add_old_probes(old
);
785 pthread_mutex_unlock(&tracepoint_mutex
);
790 * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
791 * @name: tracepoint name
792 * @probe: probe function pointer
794 * caller must call tracepoint_probe_update_all()
795 * Called with the tracepoint mutex held.
797 int tracepoint_probe_unregister_noupdate(const char *name
, void (*probe
)(void),
803 DBG("Un-registering probe from tracepoint %s", name
);
805 pthread_mutex_lock(&tracepoint_mutex
);
806 old
= tracepoint_remove_probe(name
, probe
, data
);
811 tracepoint_add_old_probes(old
);
813 pthread_mutex_unlock(&tracepoint_mutex
);
818 * tracepoint_probe_update_all - update tracepoints
820 void tracepoint_probe_update_all(void)
822 CDS_LIST_HEAD(release_probes
);
823 struct tp_probes
*pos
, *next
;
825 pthread_mutex_lock(&tracepoint_mutex
);
829 if (!cds_list_empty(&old_probes
))
830 cds_list_replace_init(&old_probes
, &release_probes
);
833 tracepoint_update_probes();
834 /* Wait for grace period between update_probes and free. */
835 lttng_ust_synchronize_trace();
836 cds_list_for_each_entry_safe(pos
, next
, &release_probes
, u
.list
) {
837 cds_list_del(&pos
->u
.list
);
841 pthread_mutex_unlock(&tracepoint_mutex
);
844 void tracepoint_set_new_tracepoint_cb(void (*cb
)(struct lttng_ust_tracepoint
*))
846 new_tracepoint_cb
= cb
;
849 static void new_tracepoints(struct lttng_ust_tracepoint
* const *start
,
850 struct lttng_ust_tracepoint
* const *end
)
852 if (new_tracepoint_cb
) {
853 struct lttng_ust_tracepoint
* const *t
;
855 for (t
= start
; t
< end
; t
++) {
857 new_tracepoint_cb(*t
);
863 * tracepoint_{un,}register_lib is meant to be looked up by instrumented
864 * applications through dlsym(). If found, those can register their
865 * tracepoints, else those tracepoints will not be available for
866 * tracing. The number at the end of those symbols acts as a major
867 * version for tracepoints.
869 * Older instrumented applications should still work with newer
870 * liblttng-ust, but it is fine that instrumented applications compiled
871 * against recent liblttng-ust headers require a recent liblttng-ust
872 * runtime for those tracepoints to be taken into account.
874 int tracepoint_register_lib(struct lttng_ust_tracepoint
* const *tracepoints_start
,
875 int tracepoints_count
)
877 struct tracepoint_lib
*pl
, *iter
;
881 pl
= (struct tracepoint_lib
*) zmalloc(sizeof(struct tracepoint_lib
));
883 PERROR("Unable to register tracepoint lib");
886 pl
->tracepoints_start
= tracepoints_start
;
887 pl
->tracepoints_count
= tracepoints_count
;
888 CDS_INIT_LIST_HEAD(&pl
->callsites
);
890 pthread_mutex_lock(&tracepoint_mutex
);
892 * We sort the libs by struct lib pointer address.
894 cds_list_for_each_entry_reverse(iter
, &libs
, list
) {
895 BUG_ON(iter
== pl
); /* Should never be in the list twice */
897 /* We belong to the location right after iter. */
898 cds_list_add(&pl
->list
, &iter
->list
);
902 /* We should be added at the head of the list */
903 cds_list_add(&pl
->list
, &libs
);
905 new_tracepoints(tracepoints_start
, tracepoints_start
+ tracepoints_count
);
906 lib_register_callsites(pl
);
907 lib_update_tracepoints(pl
);
908 pthread_mutex_unlock(&tracepoint_mutex
);
910 DBG("just registered a tracepoints section from %p and having %d tracepoints",
911 tracepoints_start
, tracepoints_count
);
915 for (i
= 0; i
< tracepoints_count
; i
++) {
916 DBG("registered tracepoint: %s", tracepoints_start
[i
]->name
);
923 int tracepoint_unregister_lib(struct lttng_ust_tracepoint
* const *tracepoints_start
)
925 struct tracepoint_lib
*lib
;
927 pthread_mutex_lock(&tracepoint_mutex
);
928 cds_list_for_each_entry(lib
, &libs
, list
) {
929 if (lib
->tracepoints_start
!= tracepoints_start
)
932 cds_list_del(&lib
->list
);
934 * Unregistering a callsite also decreases the
935 * callsite reference count of the corresponding
936 * tracepoint, and disables the tracepoint if
937 * the reference count drops to zero.
939 lib_unregister_callsites(lib
);
940 DBG("just unregistered a tracepoints section from %p",
941 lib
->tracepoints_start
);
945 pthread_mutex_unlock(&tracepoint_mutex
);
950 * Report in debug message whether the compiler correctly supports weak
951 * hidden symbols. This test checks that the address associated with two
952 * weak symbols with hidden visibility is the same when declared within
953 * two compile units part of the same module.
955 static void check_weak_hidden(void)
957 DBG("Your compiler treats weak symbols with hidden visibility for integer objects as %s between compile units part of the same module.",
958 &__tracepoint_test_symbol1
== lttng_ust_tp_check_weak_hidden1() ?
960 "DIFFERENT addresses");
961 DBG("Your compiler treats weak symbols with hidden visibility for pointer objects as %s between compile units part of the same module.",
962 &__tracepoint_test_symbol2
== lttng_ust_tp_check_weak_hidden2() ?
964 "DIFFERENT addresses");
965 DBG("Your compiler treats weak symbols with hidden visibility for 24-byte structure objects as %s between compile units part of the same module.",
966 &__tracepoint_test_symbol3
== lttng_ust_tp_check_weak_hidden3() ?
968 "DIFFERENT addresses");
971 void init_tracepoint(void)
973 if (uatomic_xchg(&initialized
, 1) == 1)
979 void exit_tracepoint(void)
985 * Create the wrapper symbols.
987 #undef tp_rcu_read_lock
988 #undef tp_rcu_read_unlock
989 #undef tp_rcu_dereference
991 void tp_rcu_read_lock(void)
993 lttng_ust_urcu_read_lock();
996 void tp_rcu_read_unlock(void)
998 lttng_ust_urcu_read_unlock();
1001 void *tp_rcu_dereference_sym(void *p
)
1003 return lttng_ust_rcu_dereference(p
);
1007 * Programs that have threads that survive after they exit, and therefore call
1008 * library destructors, should disable the tracepoint destructors by calling
1009 * tp_disable_destructors(). This will leak the tracepoint
1010 * instrumentation library shared object, leaving its teardown to the operating
1011 * system process teardown.
1013 * To access and/or modify this value, users need to use a combination of
1014 * dlopen(3) and dlsym(3) to get an handle on the
1015 * tp_disable_destructors and tp_get_destructors_state symbols below.
1017 void tp_disable_destructors(void)
1019 uatomic_set(&tracepoint_destructors_state
, 0);
1023 * Returns 1 if the destructors are enabled and should be executed.
1024 * Returns 0 if the destructors are disabled.
1026 int tp_get_destructors_state(void)
1028 return uatomic_read(&tracepoint_destructors_state
);
1031 void lttng_ust_synchronize_trace(void)
1033 lttng_ust_urcu_synchronize_rcu();