2 * Copyright (C) 2008 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.
24 #include <ust/tracepoint.h>
25 #include <ust/tracepoint-internal.h>
27 #include <ust/kcompat/kcompat.h>
29 #include <urcu/hlist.h>
31 #include "usterr_signal_safe.h"
33 //extern struct tracepoint __start___tracepoints[] __attribute__((visibility("hidden")));
34 //extern struct tracepoint __stop___tracepoints[] __attribute__((visibility("hidden")));
36 /* Set to 1 to enable tracepoint debug output */
37 static const int tracepoint_debug
;
39 /* libraries that contain tracepoints (struct tracepoint_lib) */
40 static CDS_LIST_HEAD(libs
);
43 * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
44 * builtin and module tracepoints and the hash table.
46 static DEFINE_MUTEX(tracepoints_mutex
);
49 * Tracepoint hash table, containing the active tracepoints.
50 * Protected by tracepoints_mutex.
52 #define TRACEPOINT_HASH_BITS 6
53 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
54 static struct cds_hlist_head tracepoint_table
[TRACEPOINT_TABLE_SIZE
];
58 * It is used to to delay the free of multiple probes array until a quiescent
60 * Tracepoint entries modifications are protected by the tracepoints_mutex.
62 struct tracepoint_entry
{
63 struct cds_hlist_node hlist
;
64 struct tracepoint_probe
*probes
;
65 int refcount
; /* Number of times armed. 0 if disarmed. */
71 //ust// struct rcu_head rcu;
72 struct cds_list_head list
;
74 struct tracepoint_probe probes
[0];
77 static inline void *allocate_probes(int count
)
79 struct tp_probes
*p
= zmalloc(count
* sizeof(struct tracepoint_probe
)
80 + sizeof(struct tp_probes
));
81 return p
== NULL
? NULL
: p
->probes
;
84 //ust// static void rcu_free_old_probes(struct rcu_head *head)
86 //ust// kfree(container_of(head, struct tp_probes, u.rcu));
89 static inline void release_probes(void *old
)
92 struct tp_probes
*tp_probes
= _ust_container_of(old
,
93 struct tp_probes
, probes
[0]);
94 //ust// call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
100 static void debug_print_probes(struct tracepoint_entry
*entry
)
104 if (!tracepoint_debug
|| !entry
->probes
)
107 for (i
= 0; entry
->probes
[i
].func
; i
++)
108 DBG("Probe %d : %p", i
, entry
->probes
[i
].func
);
112 tracepoint_entry_add_probe(struct tracepoint_entry
*entry
,
113 void *probe
, void *data
)
116 struct tracepoint_probe
*old
, *new;
120 debug_print_probes(entry
);
123 /* (N -> N+1), (N != 0, 1) probes */
124 for (nr_probes
= 0; old
[nr_probes
].func
; nr_probes
++)
125 if (old
[nr_probes
].func
== probe
&&
126 old
[nr_probes
].data
== data
)
127 return ERR_PTR(-EEXIST
);
129 /* + 2 : one for new probe, one for NULL func */
130 new = allocate_probes(nr_probes
+ 2);
132 return ERR_PTR(-ENOMEM
);
134 memcpy(new, old
, nr_probes
* sizeof(struct tracepoint_probe
));
135 new[nr_probes
].func
= probe
;
136 new[nr_probes
].data
= data
;
137 new[nr_probes
+ 1].func
= NULL
;
138 entry
->refcount
= nr_probes
+ 1;
140 debug_print_probes(entry
);
145 tracepoint_entry_remove_probe(struct tracepoint_entry
*entry
, void *probe
,
148 int nr_probes
= 0, nr_del
= 0, i
;
149 struct tracepoint_probe
*old
, *new;
154 return ERR_PTR(-ENOENT
);
156 debug_print_probes(entry
);
157 /* (N -> M), (N > 1, M >= 0) probes */
158 for (nr_probes
= 0; old
[nr_probes
].func
; nr_probes
++) {
160 (old
[nr_probes
].func
== probe
&&
161 old
[nr_probes
].data
== data
))
165 if (nr_probes
- nr_del
== 0) {
166 /* N -> 0, (N > 1) */
167 entry
->probes
= NULL
;
169 debug_print_probes(entry
);
173 /* N -> M, (N > 1, M > 0) */
175 new = allocate_probes(nr_probes
- nr_del
+ 1);
177 return ERR_PTR(-ENOMEM
);
178 for (i
= 0; old
[i
].func
; i
++)
180 (old
[i
].func
!= probe
|| old
[i
].data
!= data
))
182 new[nr_probes
- nr_del
].func
= NULL
;
183 entry
->refcount
= nr_probes
- nr_del
;
186 debug_print_probes(entry
);
191 * Get tracepoint if the tracepoint is present in the tracepoint hash table.
192 * Must be called with tracepoints_mutex held.
193 * Returns NULL if not present.
195 static struct tracepoint_entry
*get_tracepoint(const char *name
)
197 struct cds_hlist_head
*head
;
198 struct cds_hlist_node
*node
;
199 struct tracepoint_entry
*e
;
200 u32 hash
= jhash(name
, strlen(name
), 0);
202 head
= &tracepoint_table
[hash
& (TRACEPOINT_TABLE_SIZE
- 1)];
203 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
204 if (!strcmp(name
, e
->name
))
211 * Add the tracepoint to the tracepoint hash table. Must be called with
212 * tracepoints_mutex held.
214 static struct tracepoint_entry
*add_tracepoint(const char *name
)
216 struct cds_hlist_head
*head
;
217 struct cds_hlist_node
*node
;
218 struct tracepoint_entry
*e
;
219 size_t name_len
= strlen(name
) + 1;
220 u32 hash
= jhash(name
, name_len
-1, 0);
222 head
= &tracepoint_table
[hash
& (TRACEPOINT_TABLE_SIZE
- 1)];
223 cds_hlist_for_each_entry(e
, node
, head
, hlist
) {
224 if (!strcmp(name
, e
->name
)) {
225 DBG("tracepoint %s busy", name
);
226 return ERR_PTR(-EEXIST
); /* Already there */
230 * Using zmalloc here to allocate a variable length element. Could
231 * cause some memory fragmentation if overused.
233 e
= zmalloc(sizeof(struct tracepoint_entry
) + name_len
);
235 return ERR_PTR(-ENOMEM
);
236 memcpy(&e
->name
[0], name
, name_len
);
239 cds_hlist_add_head(&e
->hlist
, head
);
244 * Remove the tracepoint from the tracepoint hash table. Must be called with
247 static inline void remove_tracepoint(struct tracepoint_entry
*e
)
249 cds_hlist_del(&e
->hlist
);
254 * Sets the probe callback corresponding to one tracepoint.
256 static void set_tracepoint(struct tracepoint_entry
**entry
,
257 struct tracepoint
*elem
, int active
)
259 WARN_ON(strcmp((*entry
)->name
, elem
->name
) != 0);
262 * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new
263 * probe callbacks array is consistent before setting a pointer to it.
264 * This array is referenced by __DO_TRACE from
265 * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
268 rcu_assign_pointer(elem
->probes
, (*entry
)->probes
);
269 elem
->state
= active
;
273 * Disable a tracepoint and its probe callback.
274 * Note: only waiting an RCU period after setting elem->call to the empty
275 * function insures that the original callback is not used anymore. This insured
276 * by preempt_disable around the call site.
278 static void disable_tracepoint(struct tracepoint
*elem
)
281 rcu_assign_pointer(elem
->probes
, NULL
);
285 * tracepoint_update_probe_range - Update a probe range
286 * @begin: beginning of the range
287 * @end: end of the range
289 * Updates the probe callback corresponding to a range of tracepoints.
291 void tracepoint_update_probe_range(struct tracepoint
* const *begin
,
292 struct tracepoint
* const *end
)
294 struct tracepoint
* const *iter
;
295 struct tracepoint_entry
*mark_entry
;
297 pthread_mutex_lock(&tracepoints_mutex
);
298 for (iter
= begin
; iter
< end
; iter
++) {
300 continue; /* skip dummy */
301 if (!(*iter
)->name
) {
302 disable_tracepoint(*iter
);
305 mark_entry
= get_tracepoint((*iter
)->name
);
307 set_tracepoint(&mark_entry
, *iter
,
308 !!mark_entry
->refcount
);
310 disable_tracepoint(*iter
);
313 pthread_mutex_unlock(&tracepoints_mutex
);
316 static void lib_update_tracepoints(void)
318 struct tracepoint_lib
*lib
;
320 //ust// pthread_mutex_lock(&module_mutex);
321 cds_list_for_each_entry(lib
, &libs
, list
)
322 tracepoint_update_probe_range(lib
->tracepoints_start
,
323 lib
->tracepoints_start
+ lib
->tracepoints_count
);
324 //ust// pthread_mutex_unlock(&module_mutex);
328 * Update probes, removing the faulty probes.
330 static void tracepoint_update_probes(void)
332 /* Core kernel tracepoints */
333 //ust// tracepoint_update_probe_range(__start___tracepoints,
334 //ust// __stop___tracepoints);
335 /* tracepoints in modules. */
336 lib_update_tracepoints();
339 static struct tracepoint_probe
*
340 tracepoint_add_probe(const char *name
, void *probe
, void *data
)
342 struct tracepoint_entry
*entry
;
343 struct tracepoint_probe
*old
;
345 entry
= get_tracepoint(name
);
347 entry
= add_tracepoint(name
);
349 return (struct tracepoint_probe
*)entry
;
351 old
= tracepoint_entry_add_probe(entry
, probe
, data
);
352 if (IS_ERR(old
) && !entry
->refcount
)
353 remove_tracepoint(entry
);
358 * __tracepoint_probe_register - Connect a probe to a tracepoint
359 * @name: tracepoint name
360 * @probe: probe handler
362 * Returns 0 if ok, error value on error.
363 * The probe address must at least be aligned on the architecture pointer size.
365 int __tracepoint_probe_register(const char *name
, void *probe
, void *data
)
369 pthread_mutex_lock(&tracepoints_mutex
);
370 old
= tracepoint_add_probe(name
, probe
, data
);
371 pthread_mutex_unlock(&tracepoints_mutex
);
375 tracepoint_update_probes(); /* may update entry */
380 static void *tracepoint_remove_probe(const char *name
, void *probe
, void *data
)
382 struct tracepoint_entry
*entry
;
385 entry
= get_tracepoint(name
);
387 return ERR_PTR(-ENOENT
);
388 old
= tracepoint_entry_remove_probe(entry
, probe
, data
);
391 if (!entry
->refcount
)
392 remove_tracepoint(entry
);
397 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
398 * @name: tracepoint name
399 * @probe: probe function pointer
400 * @probe: probe data pointer
402 * We do not need to call a synchronize_sched to make sure the probes have
403 * finished running before doing a module unload, because the module unload
404 * itself uses stop_machine(), which insures that every preempt disabled section
407 int __tracepoint_probe_unregister(const char *name
, void *probe
, void *data
)
411 pthread_mutex_lock(&tracepoints_mutex
);
412 old
= tracepoint_remove_probe(name
, probe
, data
);
413 pthread_mutex_unlock(&tracepoints_mutex
);
417 tracepoint_update_probes(); /* may update entry */
422 static CDS_LIST_HEAD(old_probes
);
423 static int need_update
;
425 static void tracepoint_add_old_probes(void *old
)
429 struct tp_probes
*tp_probes
= _ust_container_of(old
,
430 struct tp_probes
, probes
[0]);
431 cds_list_add(&tp_probes
->u
.list
, &old_probes
);
436 * tracepoint_probe_register_noupdate - register a probe but not connect
437 * @name: tracepoint name
438 * @probe: probe handler
440 * caller must call tracepoint_probe_update_all()
442 int tracepoint_probe_register_noupdate(const char *name
, void *probe
,
447 pthread_mutex_lock(&tracepoints_mutex
);
448 old
= tracepoint_add_probe(name
, probe
, data
);
450 pthread_mutex_unlock(&tracepoints_mutex
);
453 tracepoint_add_old_probes(old
);
454 pthread_mutex_unlock(&tracepoints_mutex
);
457 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
460 * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
461 * @name: tracepoint name
462 * @probe: probe function pointer
464 * caller must call tracepoint_probe_update_all()
466 int tracepoint_probe_unregister_noupdate(const char *name
, void *probe
,
471 pthread_mutex_lock(&tracepoints_mutex
);
472 old
= tracepoint_remove_probe(name
, probe
, data
);
474 pthread_mutex_unlock(&tracepoints_mutex
);
477 tracepoint_add_old_probes(old
);
478 pthread_mutex_unlock(&tracepoints_mutex
);
481 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
484 * tracepoint_probe_update_all - update tracepoints
486 void tracepoint_probe_update_all(void)
488 CDS_LIST_HEAD(release_probes
);
489 struct tp_probes
*pos
, *next
;
491 pthread_mutex_lock(&tracepoints_mutex
);
493 pthread_mutex_unlock(&tracepoints_mutex
);
496 if (!cds_list_empty(&old_probes
))
497 cds_list_replace_init(&old_probes
, &release_probes
);
499 pthread_mutex_unlock(&tracepoints_mutex
);
501 tracepoint_update_probes();
502 cds_list_for_each_entry_safe(pos
, next
, &release_probes
, u
.list
) {
503 cds_list_del(&pos
->u
.list
);
504 //ust// call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
509 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
512 * Returns 0 if current not found.
513 * Returns 1 if current found.
515 int lib_get_iter_tracepoints(struct tracepoint_iter
*iter
)
517 struct tracepoint_lib
*iter_lib
;
520 //ust// pthread_mutex_lock(&module_mutex);
521 cds_list_for_each_entry(iter_lib
, &libs
, list
) {
522 if (iter_lib
< iter
->lib
)
524 else if (iter_lib
> iter
->lib
)
525 iter
->tracepoint
= NULL
;
526 found
= tracepoint_get_iter_range(&iter
->tracepoint
,
527 iter_lib
->tracepoints_start
,
528 iter_lib
->tracepoints_start
+ iter_lib
->tracepoints_count
);
530 iter
->lib
= iter_lib
;
534 //ust// pthread_mutex_unlock(&module_mutex);
539 * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
540 * @tracepoint: current tracepoints (in), next tracepoint (out)
541 * @begin: beginning of the range
542 * @end: end of the range
544 * Returns whether a next tracepoint has been found (1) or not (0).
545 * Will return the first tracepoint in the range if the input tracepoint is
548 int tracepoint_get_iter_range(struct tracepoint
* const **tracepoint
,
549 struct tracepoint
* const *begin
, struct tracepoint
* const *end
)
551 if (!*tracepoint
&& begin
!= end
)
553 while (*tracepoint
>= begin
&& *tracepoint
< end
) {
555 (*tracepoint
)++; /* skip dummy */
561 //ust// EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);
563 static void tracepoint_get_iter(struct tracepoint_iter
*iter
)
567 //ust// /* Core kernel tracepoints */
568 //ust// if (!iter->module) {
569 //ust// found = tracepoint_get_iter_range(&iter->tracepoint,
570 //ust// __start___tracepoints, __stop___tracepoints);
574 /* tracepoints in libs. */
575 found
= lib_get_iter_tracepoints(iter
);
578 tracepoint_iter_reset(iter
);
581 void tracepoint_iter_start(struct tracepoint_iter
*iter
)
583 tracepoint_get_iter(iter
);
585 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_start);
587 void tracepoint_iter_next(struct tracepoint_iter
*iter
)
591 * iter->tracepoint may be invalid because we blindly incremented it.
592 * Make sure it is valid by marshalling on the tracepoints, getting the
593 * tracepoints from following modules if necessary.
595 tracepoint_get_iter(iter
);
597 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_next);
599 void tracepoint_iter_stop(struct tracepoint_iter
*iter
)
602 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
604 void tracepoint_iter_reset(struct tracepoint_iter
*iter
)
606 //ust// iter->module = NULL;
607 iter
->tracepoint
= NULL
;
609 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
611 //ust// #ifdef CONFIG_MODULES
613 //ust// int tracepoint_module_notify(struct notifier_block *self,
614 //ust// unsigned long val, void *data)
616 //ust// struct module *mod = data;
618 //ust// switch (val) {
619 //ust// case MODULE_STATE_COMING:
620 //ust// tracepoint_update_probe_range(mod->tracepoints,
621 //ust// mod->tracepoints + mod->num_tracepoints);
623 //ust// case MODULE_STATE_GOING:
624 //ust// tracepoint_update_probe_range(mod->tracepoints,
625 //ust// mod->tracepoints + mod->num_tracepoints);
631 //ust// struct notifier_block tracepoint_module_nb = {
632 //ust// .notifier_call = tracepoint_module_notify,
633 //ust// .priority = 0,
636 //ust// static int init_tracepoints(void)
638 //ust// return register_module_notifier(&tracepoint_module_nb);
640 //ust// __initcall(init_tracepoints);
642 //ust// #endif /* CONFIG_MODULES */
644 static void (*new_tracepoint_cb
)(struct tracepoint
*) = NULL
;
646 void tracepoint_set_new_tracepoint_cb(void (*cb
)(struct tracepoint
*))
648 new_tracepoint_cb
= cb
;
651 static void new_tracepoints(struct tracepoint
* const *start
, struct tracepoint
* const *end
)
653 if (new_tracepoint_cb
) {
654 struct tracepoint
* const *t
;
656 for(t
= start
; t
< end
; t
++) {
658 new_tracepoint_cb(*t
);
663 int tracepoint_register_lib(struct tracepoint
* const *tracepoints_start
, int tracepoints_count
)
665 struct tracepoint_lib
*pl
, *iter
;
667 pl
= (struct tracepoint_lib
*) zmalloc(sizeof(struct tracepoint_lib
));
669 pl
->tracepoints_start
= tracepoints_start
;
670 pl
->tracepoints_count
= tracepoints_count
;
672 /* FIXME: maybe protect this with its own mutex? */
673 pthread_mutex_lock(&tracepoints_mutex
);
675 * We sort the libs by struct lib pointer address.
677 cds_list_for_each_entry_reverse(iter
, &libs
, list
) {
678 BUG_ON(iter
== pl
); /* Should never be in the list twice */
680 /* We belong to the location right after iter. */
681 cds_list_add(&pl
->list
, &iter
->list
);
685 /* We should be added at the head of the list */
686 cds_list_add(&pl
->list
, &libs
);
688 pthread_mutex_unlock(&tracepoints_mutex
);
690 new_tracepoints(tracepoints_start
, tracepoints_start
+ tracepoints_count
);
692 /* FIXME: update just the loaded lib */
693 lib_update_tracepoints();
695 /* tracepoints_count - 1: skip dummy */
696 DBG("just registered a tracepoints section from %p and having %d tracepoints (minus dummy tracepoints)", tracepoints_start
, tracepoints_count
);
701 int tracepoint_unregister_lib(struct tracepoint
* const *tracepoints_start
)
703 struct tracepoint_lib
*lib
;
705 pthread_mutex_lock(&tracepoints_mutex
);
707 cds_list_for_each_entry(lib
, &libs
, list
) {
708 if (lib
->tracepoints_start
== tracepoints_start
) {
709 struct tracepoint_lib
*lib2free
= lib
;
710 cds_list_del(&lib
->list
);
716 pthread_mutex_unlock(&tracepoints_mutex
);