Commit | Line | Data |
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f99be407 | 1 | /* |
b27f8e75 | 2 | * Copyright (C) 2008-2011 Mathieu Desnoyers |
1f8b0dff | 3 | * Copyright (C) 2009 Pierre-Marc Fournier |
f99be407 | 4 | * |
34e4b7db PMF |
5 | * This library is free software; you can redistribute it and/or |
6 | * modify it under the terms of the GNU Lesser General Public | |
f37142a4 MD |
7 | * License as published by the Free Software Foundation; |
8 | * version 2.1 of the License. | |
f99be407 | 9 | * |
34e4b7db | 10 | * This library is distributed in the hope that it will be useful, |
f99be407 | 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
34e4b7db PMF |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | * Lesser General Public License for more details. | |
f99be407 | 14 | * |
34e4b7db PMF |
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 | |
1f8b0dff PMF |
18 | * |
19 | * Ported to userspace by Pierre-Marc Fournier. | |
f99be407 | 20 | */ |
1f8b0dff | 21 | |
b0c4126f | 22 | #define _LGPL_SOURCE |
474d745f | 23 | #include <errno.h> |
b728d87e MD |
24 | #include <stdint.h> |
25 | #include <stddef.h> | |
44c72f10 | 26 | |
b728d87e | 27 | #include <urcu/arch.h> |
b7ea1a1c | 28 | #include <urcu-bp.h> |
10c56168 | 29 | #include <urcu/hlist.h> |
edaa1431 | 30 | #include <urcu/uatomic.h> |
b728d87e | 31 | #include <urcu/compiler.h> |
44c72f10 MD |
32 | |
33 | #include <lttng/tracepoint.h> | |
ff412fb5 | 34 | #include <lttng/ust-abi.h> /* for LTTNG_UST_SYM_NAME_LEN */ |
44c72f10 MD |
35 | |
36 | #include <usterr-signal-safe.h> | |
35897f8b | 37 | #include <helper.h> |
474d745f | 38 | |
23c8854a | 39 | #include "tracepoint-internal.h" |
b751f722 | 40 | #include "ltt-tracer-core.h" |
596c4223 | 41 | #include "jhash.h" |
8f3f8c99 | 42 | #include "error.h" |
b0c4126f | 43 | |
f99be407 PMF |
44 | /* Set to 1 to enable tracepoint debug output */ |
45 | static const int tracepoint_debug; | |
b27f8e75 MD |
46 | static int initialized; |
47 | static void (*new_tracepoint_cb)(struct tracepoint *); | |
f99be407 | 48 | |
8792fbae MD |
49 | /* |
50 | * tracepoint_mutex nests inside UST mutex. | |
51 | * | |
52 | * Note about interaction with fork/clone: UST does not hold the | |
53 | * tracepoint mutex across fork/clone because it is either: | |
54 | * - nested within UST mutex, in which case holding the UST mutex across | |
55 | * fork/clone suffice, | |
56 | * - taken by a library constructor, which should never race with a | |
57 | * fork/clone if the application is expected to continue running with | |
58 | * the same memory layout (no following exec()). | |
59 | */ | |
60 | static pthread_mutex_t tracepoint_mutex = PTHREAD_MUTEX_INITIALIZER; | |
61 | ||
efa2c591 MD |
62 | /* |
63 | * libraries that contain tracepoints (struct tracepoint_lib). | |
8792fbae | 64 | * Protected by tracepoint mutex. |
efa2c591 | 65 | */ |
0222e121 | 66 | static CDS_LIST_HEAD(libs); |
474d745f | 67 | |
f99be407 | 68 | /* |
8792fbae | 69 | * The tracepoint mutex protects the library tracepoints, the hash table, and |
17dfb34b | 70 | * the library list. |
8792fbae | 71 | * All calls to the tracepoint API must be protected by the tracepoint mutex, |
17dfb34b | 72 | * excepts calls to tracepoint_register_lib and |
8792fbae | 73 | * tracepoint_unregister_lib, which take the tracepoint mutex themselves. |
f99be407 | 74 | */ |
f99be407 PMF |
75 | |
76 | /* | |
77 | * Tracepoint hash table, containing the active tracepoints. | |
8792fbae | 78 | * Protected by tracepoint mutex. |
f99be407 PMF |
79 | */ |
80 | #define TRACEPOINT_HASH_BITS 6 | |
81 | #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) | |
10c56168 | 82 | static struct cds_hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; |
f99be407 | 83 | |
b27f8e75 MD |
84 | static CDS_LIST_HEAD(old_probes); |
85 | static int need_update; | |
86 | ||
f99be407 PMF |
87 | /* |
88 | * Note about RCU : | |
89 | * It is used to to delay the free of multiple probes array until a quiescent | |
90 | * state is reached. | |
8792fbae | 91 | * Tracepoint entries modifications are protected by the tracepoint mutex. |
f99be407 PMF |
92 | */ |
93 | struct tracepoint_entry { | |
10c56168 | 94 | struct cds_hlist_node hlist; |
b979b346 | 95 | struct tracepoint_probe *probes; |
f99be407 PMF |
96 | int refcount; /* Number of times armed. 0 if disarmed. */ |
97 | char name[0]; | |
98 | }; | |
99 | ||
100 | struct tp_probes { | |
101 | union { | |
0222e121 | 102 | struct cds_list_head list; |
ade7037b MD |
103 | /* Field below only used for call_rcu scheme */ |
104 | /* struct rcu_head head; */ | |
f99be407 | 105 | } u; |
b979b346 | 106 | struct tracepoint_probe probes[0]; |
f99be407 PMF |
107 | }; |
108 | ||
efa2c591 | 109 | static void *allocate_probes(int count) |
f99be407 | 110 | { |
b979b346 | 111 | struct tp_probes *p = zmalloc(count * sizeof(struct tracepoint_probe) |
909bc43f | 112 | + sizeof(struct tp_probes)); |
f99be407 PMF |
113 | return p == NULL ? NULL : p->probes; |
114 | } | |
115 | ||
efa2c591 | 116 | static void release_probes(void *old) |
f99be407 PMF |
117 | { |
118 | if (old) { | |
b728d87e | 119 | struct tp_probes *tp_probes = caa_container_of(old, |
f99be407 | 120 | struct tp_probes, probes[0]); |
474d745f | 121 | synchronize_rcu(); |
909bc43f | 122 | free(tp_probes); |
f99be407 PMF |
123 | } |
124 | } | |
125 | ||
126 | static void debug_print_probes(struct tracepoint_entry *entry) | |
127 | { | |
128 | int i; | |
129 | ||
9dec086e | 130 | if (!tracepoint_debug || !entry->probes) |
f99be407 PMF |
131 | return; |
132 | ||
9dec086e NC |
133 | for (i = 0; entry->probes[i].func; i++) |
134 | DBG("Probe %d : %p", i, entry->probes[i].func); | |
f99be407 PMF |
135 | } |
136 | ||
137 | static void * | |
9dec086e NC |
138 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, |
139 | void *probe, void *data) | |
f99be407 PMF |
140 | { |
141 | int nr_probes = 0; | |
b979b346 | 142 | struct tracepoint_probe *old, *new; |
f99be407 PMF |
143 | |
144 | WARN_ON(!probe); | |
145 | ||
146 | debug_print_probes(entry); | |
9dec086e | 147 | old = entry->probes; |
f99be407 PMF |
148 | if (old) { |
149 | /* (N -> N+1), (N != 0, 1) probes */ | |
9dec086e NC |
150 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
151 | if (old[nr_probes].func == probe && | |
152 | old[nr_probes].data == data) | |
f99be407 PMF |
153 | return ERR_PTR(-EEXIST); |
154 | } | |
155 | /* + 2 : one for new probe, one for NULL func */ | |
156 | new = allocate_probes(nr_probes + 2); | |
157 | if (new == NULL) | |
158 | return ERR_PTR(-ENOMEM); | |
159 | if (old) | |
b979b346 | 160 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_probe)); |
9dec086e NC |
161 | new[nr_probes].func = probe; |
162 | new[nr_probes].data = data; | |
163 | new[nr_probes + 1].func = NULL; | |
f99be407 | 164 | entry->refcount = nr_probes + 1; |
9dec086e | 165 | entry->probes = new; |
f99be407 PMF |
166 | debug_print_probes(entry); |
167 | return old; | |
168 | } | |
169 | ||
170 | static void * | |
9dec086e NC |
171 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe, |
172 | void *data) | |
f99be407 PMF |
173 | { |
174 | int nr_probes = 0, nr_del = 0, i; | |
b979b346 | 175 | struct tracepoint_probe *old, *new; |
f99be407 | 176 | |
9dec086e | 177 | old = entry->probes; |
f99be407 PMF |
178 | |
179 | if (!old) | |
180 | return ERR_PTR(-ENOENT); | |
181 | ||
182 | debug_print_probes(entry); | |
183 | /* (N -> M), (N > 1, M >= 0) probes */ | |
9dec086e | 184 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { |
c66428ac DG |
185 | if (!probe || |
186 | (old[nr_probes].func == probe && | |
9dec086e | 187 | old[nr_probes].data == data)) |
f99be407 PMF |
188 | nr_del++; |
189 | } | |
190 | ||
191 | if (nr_probes - nr_del == 0) { | |
192 | /* N -> 0, (N > 1) */ | |
9dec086e | 193 | entry->probes = NULL; |
f99be407 PMF |
194 | entry->refcount = 0; |
195 | debug_print_probes(entry); | |
196 | return old; | |
197 | } else { | |
198 | int j = 0; | |
199 | /* N -> M, (N > 1, M > 0) */ | |
200 | /* + 1 for NULL */ | |
201 | new = allocate_probes(nr_probes - nr_del + 1); | |
202 | if (new == NULL) | |
203 | return ERR_PTR(-ENOMEM); | |
9dec086e NC |
204 | for (i = 0; old[i].func; i++) |
205 | if (probe && | |
206 | (old[i].func != probe || old[i].data != data)) | |
f99be407 | 207 | new[j++] = old[i]; |
9dec086e | 208 | new[nr_probes - nr_del].func = NULL; |
f99be407 | 209 | entry->refcount = nr_probes - nr_del; |
9dec086e | 210 | entry->probes = new; |
f99be407 PMF |
211 | } |
212 | debug_print_probes(entry); | |
213 | return old; | |
214 | } | |
215 | ||
216 | /* | |
217 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. | |
8792fbae | 218 | * Must be called with tracepoint mutex held. |
f99be407 PMF |
219 | * Returns NULL if not present. |
220 | */ | |
221 | static struct tracepoint_entry *get_tracepoint(const char *name) | |
222 | { | |
10c56168 DG |
223 | struct cds_hlist_head *head; |
224 | struct cds_hlist_node *node; | |
f99be407 | 225 | struct tracepoint_entry *e; |
ff412fb5 MD |
226 | size_t name_len = strlen(name); |
227 | uint32_t hash; | |
f99be407 | 228 | |
ff412fb5 MD |
229 | if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) { |
230 | WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1); | |
231 | name_len = LTTNG_UST_SYM_NAME_LEN - 1; | |
232 | } | |
233 | hash = jhash(name, name_len, 0); | |
f99be407 | 234 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
10c56168 | 235 | cds_hlist_for_each_entry(e, node, head, hlist) { |
ff412fb5 | 236 | if (!strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1)) |
f99be407 PMF |
237 | return e; |
238 | } | |
239 | return NULL; | |
240 | } | |
241 | ||
242 | /* | |
243 | * Add the tracepoint to the tracepoint hash table. Must be called with | |
8792fbae | 244 | * tracepoint mutex held. |
f99be407 PMF |
245 | */ |
246 | static struct tracepoint_entry *add_tracepoint(const char *name) | |
247 | { | |
10c56168 DG |
248 | struct cds_hlist_head *head; |
249 | struct cds_hlist_node *node; | |
f99be407 | 250 | struct tracepoint_entry *e; |
ff412fb5 MD |
251 | size_t name_len = strlen(name); |
252 | uint32_t hash; | |
f99be407 | 253 | |
ff412fb5 MD |
254 | if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) { |
255 | WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1); | |
256 | name_len = LTTNG_UST_SYM_NAME_LEN - 1; | |
257 | } | |
258 | hash = jhash(name, name_len, 0); | |
f99be407 | 259 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
10c56168 | 260 | cds_hlist_for_each_entry(e, node, head, hlist) { |
ff412fb5 | 261 | if (!strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1)) { |
c1f20530 | 262 | DBG("tracepoint %s busy", name); |
f99be407 PMF |
263 | return ERR_PTR(-EEXIST); /* Already there */ |
264 | } | |
265 | } | |
266 | /* | |
1dba3e6c | 267 | * Using zmalloc here to allocate a variable length element. Could |
f99be407 PMF |
268 | * cause some memory fragmentation if overused. |
269 | */ | |
ff412fb5 | 270 | e = zmalloc(sizeof(struct tracepoint_entry) + name_len + 1); |
f99be407 PMF |
271 | if (!e) |
272 | return ERR_PTR(-ENOMEM); | |
ff412fb5 MD |
273 | memcpy(&e->name[0], name, name_len + 1); |
274 | e->name[name_len] = '\0'; | |
9dec086e | 275 | e->probes = NULL; |
f99be407 | 276 | e->refcount = 0; |
10c56168 | 277 | cds_hlist_add_head(&e->hlist, head); |
f99be407 PMF |
278 | return e; |
279 | } | |
280 | ||
281 | /* | |
282 | * Remove the tracepoint from the tracepoint hash table. Must be called with | |
8792fbae | 283 | * tracepoint mutex held. |
f99be407 | 284 | */ |
efa2c591 | 285 | static void remove_tracepoint(struct tracepoint_entry *e) |
f99be407 | 286 | { |
10c56168 | 287 | cds_hlist_del(&e->hlist); |
909bc43f | 288 | free(e); |
f99be407 PMF |
289 | } |
290 | ||
291 | /* | |
292 | * Sets the probe callback corresponding to one tracepoint. | |
293 | */ | |
294 | static void set_tracepoint(struct tracepoint_entry **entry, | |
295 | struct tracepoint *elem, int active) | |
296 | { | |
ff412fb5 | 297 | WARN_ON(strncmp((*entry)->name, elem->name, LTTNG_UST_SYM_NAME_LEN - 1) != 0); |
f99be407 PMF |
298 | |
299 | /* | |
0222e121 | 300 | * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new |
f99be407 PMF |
301 | * probe callbacks array is consistent before setting a pointer to it. |
302 | * This array is referenced by __DO_TRACE from | |
0222e121 | 303 | * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends() |
f99be407 PMF |
304 | * is used. |
305 | */ | |
9dec086e | 306 | rcu_assign_pointer(elem->probes, (*entry)->probes); |
f36c12ab | 307 | elem->state = active; |
f99be407 PMF |
308 | } |
309 | ||
310 | /* | |
311 | * Disable a tracepoint and its probe callback. | |
312 | * Note: only waiting an RCU period after setting elem->call to the empty | |
313 | * function insures that the original callback is not used anymore. This insured | |
314 | * by preempt_disable around the call site. | |
315 | */ | |
316 | static void disable_tracepoint(struct tracepoint *elem) | |
317 | { | |
f36c12ab | 318 | elem->state = 0; |
9dec086e | 319 | rcu_assign_pointer(elem->probes, NULL); |
f99be407 PMF |
320 | } |
321 | ||
322 | /** | |
323 | * tracepoint_update_probe_range - Update a probe range | |
324 | * @begin: beginning of the range | |
325 | * @end: end of the range | |
326 | * | |
327 | * Updates the probe callback corresponding to a range of tracepoints. | |
328 | */ | |
b27f8e75 | 329 | static |
f218ff28 MD |
330 | void tracepoint_update_probe_range(struct tracepoint * const *begin, |
331 | struct tracepoint * const *end) | |
f99be407 | 332 | { |
f218ff28 | 333 | struct tracepoint * const *iter; |
f99be407 PMF |
334 | struct tracepoint_entry *mark_entry; |
335 | ||
f99be407 | 336 | for (iter = begin; iter < end; iter++) { |
f08ebbe2 MD |
337 | if (!*iter) |
338 | continue; /* skip dummy */ | |
f218ff28 MD |
339 | if (!(*iter)->name) { |
340 | disable_tracepoint(*iter); | |
9dec086e NC |
341 | continue; |
342 | } | |
f218ff28 | 343 | mark_entry = get_tracepoint((*iter)->name); |
f99be407 | 344 | if (mark_entry) { |
f218ff28 | 345 | set_tracepoint(&mark_entry, *iter, |
f99be407 PMF |
346 | !!mark_entry->refcount); |
347 | } else { | |
f218ff28 | 348 | disable_tracepoint(*iter); |
f99be407 PMF |
349 | } |
350 | } | |
f99be407 PMF |
351 | } |
352 | ||
772030fe PMF |
353 | static void lib_update_tracepoints(void) |
354 | { | |
355 | struct tracepoint_lib *lib; | |
356 | ||
b27f8e75 | 357 | cds_list_for_each_entry(lib, &libs, list) { |
772030fe PMF |
358 | tracepoint_update_probe_range(lib->tracepoints_start, |
359 | lib->tracepoints_start + lib->tracepoints_count); | |
b27f8e75 | 360 | } |
772030fe PMF |
361 | } |
362 | ||
f99be407 PMF |
363 | /* |
364 | * Update probes, removing the faulty probes. | |
365 | */ | |
366 | static void tracepoint_update_probes(void) | |
367 | { | |
b27f8e75 | 368 | /* tracepoints registered from libraries and executable. */ |
474d745f | 369 | lib_update_tracepoints(); |
f99be407 PMF |
370 | } |
371 | ||
b979b346 | 372 | static struct tracepoint_probe * |
9dec086e | 373 | tracepoint_add_probe(const char *name, void *probe, void *data) |
f99be407 PMF |
374 | { |
375 | struct tracepoint_entry *entry; | |
b979b346 | 376 | struct tracepoint_probe *old; |
f99be407 PMF |
377 | |
378 | entry = get_tracepoint(name); | |
379 | if (!entry) { | |
380 | entry = add_tracepoint(name); | |
381 | if (IS_ERR(entry)) | |
b979b346 | 382 | return (struct tracepoint_probe *)entry; |
f99be407 | 383 | } |
9dec086e | 384 | old = tracepoint_entry_add_probe(entry, probe, data); |
f99be407 PMF |
385 | if (IS_ERR(old) && !entry->refcount) |
386 | remove_tracepoint(entry); | |
387 | return old; | |
388 | } | |
389 | ||
390 | /** | |
81614639 | 391 | * __tracepoint_probe_register - Connect a probe to a tracepoint |
f99be407 PMF |
392 | * @name: tracepoint name |
393 | * @probe: probe handler | |
394 | * | |
395 | * Returns 0 if ok, error value on error. | |
396 | * The probe address must at least be aligned on the architecture pointer size. | |
8792fbae | 397 | * Called with the tracepoint mutex held. |
f99be407 | 398 | */ |
81614639 | 399 | int __tracepoint_probe_register(const char *name, void *probe, void *data) |
f99be407 PMF |
400 | { |
401 | void *old; | |
8792fbae | 402 | int ret = 0; |
f99be407 | 403 | |
05780d81 MD |
404 | DBG("Registering probe to tracepoint %s", name); |
405 | ||
8792fbae | 406 | pthread_mutex_lock(&tracepoint_mutex); |
9dec086e | 407 | old = tracepoint_add_probe(name, probe, data); |
8792fbae MD |
408 | if (IS_ERR(old)) { |
409 | ret = PTR_ERR(old); | |
410 | goto end; | |
411 | } | |
f99be407 PMF |
412 | |
413 | tracepoint_update_probes(); /* may update entry */ | |
414 | release_probes(old); | |
8792fbae MD |
415 | end: |
416 | pthread_mutex_unlock(&tracepoint_mutex); | |
417 | return ret; | |
f99be407 | 418 | } |
f99be407 | 419 | |
9dec086e | 420 | static void *tracepoint_remove_probe(const char *name, void *probe, void *data) |
f99be407 PMF |
421 | { |
422 | struct tracepoint_entry *entry; | |
423 | void *old; | |
424 | ||
425 | entry = get_tracepoint(name); | |
426 | if (!entry) | |
427 | return ERR_PTR(-ENOENT); | |
9dec086e | 428 | old = tracepoint_entry_remove_probe(entry, probe, data); |
f99be407 PMF |
429 | if (IS_ERR(old)) |
430 | return old; | |
431 | if (!entry->refcount) | |
432 | remove_tracepoint(entry); | |
433 | return old; | |
434 | } | |
435 | ||
436 | /** | |
437 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint | |
438 | * @name: tracepoint name | |
439 | * @probe: probe function pointer | |
9dec086e | 440 | * @probe: probe data pointer |
f99be407 | 441 | */ |
81614639 | 442 | int __tracepoint_probe_unregister(const char *name, void *probe, void *data) |
f99be407 PMF |
443 | { |
444 | void *old; | |
8792fbae | 445 | int ret = 0; |
f99be407 | 446 | |
05780d81 MD |
447 | DBG("Un-registering probe from tracepoint %s", name); |
448 | ||
8792fbae | 449 | pthread_mutex_lock(&tracepoint_mutex); |
9dec086e | 450 | old = tracepoint_remove_probe(name, probe, data); |
8792fbae MD |
451 | if (IS_ERR(old)) { |
452 | ret = PTR_ERR(old); | |
453 | goto end; | |
454 | } | |
f99be407 PMF |
455 | tracepoint_update_probes(); /* may update entry */ |
456 | release_probes(old); | |
8792fbae MD |
457 | end: |
458 | pthread_mutex_unlock(&tracepoint_mutex); | |
459 | return ret; | |
f99be407 | 460 | } |
f99be407 | 461 | |
f99be407 PMF |
462 | static void tracepoint_add_old_probes(void *old) |
463 | { | |
464 | need_update = 1; | |
465 | if (old) { | |
b728d87e | 466 | struct tp_probes *tp_probes = caa_container_of(old, |
f99be407 | 467 | struct tp_probes, probes[0]); |
0222e121 | 468 | cds_list_add(&tp_probes->u.list, &old_probes); |
f99be407 PMF |
469 | } |
470 | } | |
471 | ||
472 | /** | |
473 | * tracepoint_probe_register_noupdate - register a probe but not connect | |
474 | * @name: tracepoint name | |
475 | * @probe: probe handler | |
476 | * | |
477 | * caller must call tracepoint_probe_update_all() | |
478 | */ | |
9dec086e NC |
479 | int tracepoint_probe_register_noupdate(const char *name, void *probe, |
480 | void *data) | |
f99be407 PMF |
481 | { |
482 | void *old; | |
8792fbae | 483 | int ret = 0; |
f99be407 | 484 | |
8792fbae | 485 | pthread_mutex_lock(&tracepoint_mutex); |
9dec086e | 486 | old = tracepoint_add_probe(name, probe, data); |
f99be407 | 487 | if (IS_ERR(old)) { |
8792fbae MD |
488 | ret = PTR_ERR(old); |
489 | goto end; | |
f99be407 PMF |
490 | } |
491 | tracepoint_add_old_probes(old); | |
8792fbae MD |
492 | end: |
493 | pthread_mutex_unlock(&tracepoint_mutex); | |
494 | return ret; | |
f99be407 | 495 | } |
f99be407 PMF |
496 | |
497 | /** | |
498 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect | |
499 | * @name: tracepoint name | |
500 | * @probe: probe function pointer | |
501 | * | |
502 | * caller must call tracepoint_probe_update_all() | |
8792fbae | 503 | * Called with the tracepoint mutex held. |
f99be407 | 504 | */ |
9dec086e NC |
505 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe, |
506 | void *data) | |
f99be407 PMF |
507 | { |
508 | void *old; | |
8792fbae | 509 | int ret = 0; |
f99be407 | 510 | |
05780d81 MD |
511 | DBG("Un-registering probe from tracepoint %s", name); |
512 | ||
8792fbae | 513 | pthread_mutex_lock(&tracepoint_mutex); |
9dec086e | 514 | old = tracepoint_remove_probe(name, probe, data); |
f99be407 | 515 | if (IS_ERR(old)) { |
8792fbae MD |
516 | ret = PTR_ERR(old); |
517 | goto end; | |
f99be407 PMF |
518 | } |
519 | tracepoint_add_old_probes(old); | |
8792fbae MD |
520 | end: |
521 | pthread_mutex_unlock(&tracepoint_mutex); | |
522 | return ret; | |
f99be407 | 523 | } |
f99be407 PMF |
524 | |
525 | /** | |
526 | * tracepoint_probe_update_all - update tracepoints | |
527 | */ | |
528 | void tracepoint_probe_update_all(void) | |
529 | { | |
0222e121 | 530 | CDS_LIST_HEAD(release_probes); |
f99be407 PMF |
531 | struct tp_probes *pos, *next; |
532 | ||
8792fbae | 533 | pthread_mutex_lock(&tracepoint_mutex); |
f99be407 | 534 | if (!need_update) { |
8792fbae | 535 | goto end; |
f99be407 | 536 | } |
0222e121 MD |
537 | if (!cds_list_empty(&old_probes)) |
538 | cds_list_replace_init(&old_probes, &release_probes); | |
f99be407 | 539 | need_update = 0; |
f99be407 PMF |
540 | |
541 | tracepoint_update_probes(); | |
0222e121 MD |
542 | cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
543 | cds_list_del(&pos->u.list); | |
474d745f | 544 | synchronize_rcu(); |
909bc43f | 545 | free(pos); |
f99be407 | 546 | } |
8792fbae MD |
547 | end: |
548 | pthread_mutex_unlock(&tracepoint_mutex); | |
f99be407 | 549 | } |
f99be407 | 550 | |
474d745f PMF |
551 | void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *)) |
552 | { | |
553 | new_tracepoint_cb = cb; | |
554 | } | |
f99be407 | 555 | |
f218ff28 | 556 | static void new_tracepoints(struct tracepoint * const *start, struct tracepoint * const *end) |
f99be407 | 557 | { |
f218ff28 MD |
558 | if (new_tracepoint_cb) { |
559 | struct tracepoint * const *t; | |
f08ebbe2 | 560 | |
b27f8e75 | 561 | for (t = start; t < end; t++) { |
f08ebbe2 MD |
562 | if (*t) |
563 | new_tracepoint_cb(*t); | |
474d745f PMF |
564 | } |
565 | } | |
f99be407 | 566 | } |
f99be407 | 567 | |
1622ba22 MD |
568 | static |
569 | void lib_disable_tracepoints(struct tracepoint * const *begin, | |
570 | struct tracepoint * const *end) | |
571 | { | |
572 | struct tracepoint * const *iter; | |
573 | ||
574 | for (iter = begin; iter < end; iter++) { | |
575 | if (!*iter) | |
576 | continue; /* skip dummy */ | |
577 | disable_tracepoint(*iter); | |
578 | } | |
579 | ||
580 | } | |
581 | ||
b27f8e75 MD |
582 | int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, |
583 | int tracepoints_count) | |
474d745f | 584 | { |
b467f7a7 | 585 | struct tracepoint_lib *pl, *iter; |
474d745f | 586 | |
edaa1431 MD |
587 | init_tracepoint(); |
588 | ||
1dba3e6c | 589 | pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib)); |
474d745f PMF |
590 | |
591 | pl->tracepoints_start = tracepoints_start; | |
592 | pl->tracepoints_count = tracepoints_count; | |
593 | ||
8792fbae | 594 | pthread_mutex_lock(&tracepoint_mutex); |
b467f7a7 MD |
595 | /* |
596 | * We sort the libs by struct lib pointer address. | |
597 | */ | |
598 | cds_list_for_each_entry_reverse(iter, &libs, list) { | |
599 | BUG_ON(iter == pl); /* Should never be in the list twice */ | |
600 | if (iter < pl) { | |
601 | /* We belong to the location right after iter. */ | |
602 | cds_list_add(&pl->list, &iter->list); | |
603 | goto lib_added; | |
604 | } | |
605 | } | |
606 | /* We should be added at the head of the list */ | |
0222e121 | 607 | cds_list_add(&pl->list, &libs); |
b467f7a7 | 608 | lib_added: |
474d745f PMF |
609 | new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count); |
610 | ||
b27f8e75 | 611 | /* TODO: update just the loaded lib */ |
474d745f | 612 | lib_update_tracepoints(); |
8792fbae | 613 | pthread_mutex_unlock(&tracepoint_mutex); |
474d745f | 614 | |
1fcf7ad7 MD |
615 | DBG("just registered a tracepoints section from %p and having %d tracepoints", |
616 | tracepoints_start, tracepoints_count); | |
05780d81 MD |
617 | if (ust_debug()) { |
618 | int i; | |
619 | ||
620 | for (i = 0; i < tracepoints_count; i++) { | |
621 | DBG("registered tracepoint: %s", tracepoints_start[i]->name); | |
622 | } | |
623 | } | |
9dec086e | 624 | |
474d745f PMF |
625 | return 0; |
626 | } | |
627 | ||
f218ff28 | 628 | int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start) |
474d745f | 629 | { |
24b6668c | 630 | struct tracepoint_lib *lib; |
1622ba22 | 631 | int tracepoints_count; |
24b6668c | 632 | |
8792fbae | 633 | pthread_mutex_lock(&tracepoint_mutex); |
0222e121 | 634 | cds_list_for_each_entry(lib, &libs, list) { |
f218ff28 | 635 | if (lib->tracepoints_start == tracepoints_start) { |
24b6668c | 636 | struct tracepoint_lib *lib2free = lib; |
1622ba22 | 637 | |
0222e121 | 638 | cds_list_del(&lib->list); |
1622ba22 | 639 | tracepoints_count = lib->tracepoints_count; |
24b6668c | 640 | free(lib2free); |
1622ba22 | 641 | goto found; |
24b6668c PMF |
642 | } |
643 | } | |
1622ba22 MD |
644 | goto end; |
645 | found: | |
646 | /* | |
647 | * Force tracepoint disarm for all tracepoints of this lib. | |
648 | * This takes care of destructor of library that would leave a | |
649 | * LD_PRELOAD wrapper override function enabled for tracing, but | |
650 | * the session teardown would not be able to reach the | |
651 | * tracepoint anymore to disable it. | |
652 | */ | |
653 | lib_disable_tracepoints(tracepoints_start, | |
654 | tracepoints_start + tracepoints_count); | |
655 | DBG("just unregistered a tracepoints section from %p", | |
656 | tracepoints_start); | |
657 | end: | |
8792fbae | 658 | pthread_mutex_unlock(&tracepoint_mutex); |
474d745f PMF |
659 | return 0; |
660 | } | |
b27f8e75 | 661 | |
edaa1431 | 662 | void init_tracepoint(void) |
b27f8e75 | 663 | { |
edaa1431 MD |
664 | if (uatomic_xchg(&initialized, 1) == 1) |
665 | return; | |
5e96a467 | 666 | init_usterr(); |
b27f8e75 MD |
667 | } |
668 | ||
edaa1431 | 669 | void exit_tracepoint(void) |
b27f8e75 | 670 | { |
17dfb34b | 671 | initialized = 0; |
b27f8e75 | 672 | } |
40b2b5a4 MD |
673 | |
674 | /* | |
675 | * Create the wrapper symbols. | |
676 | */ | |
677 | #undef tp_rcu_read_lock_bp | |
678 | #undef tp_rcu_read_unlock_bp | |
679 | #undef tp_rcu_dereference_bp | |
680 | ||
681 | void tp_rcu_read_lock_bp(void) | |
682 | { | |
683 | rcu_read_lock_bp(); | |
684 | } | |
685 | ||
686 | void tp_rcu_read_unlock_bp(void) | |
687 | { | |
688 | rcu_read_unlock_bp(); | |
689 | } | |
690 | ||
691 | void *tp_rcu_dereference_sym_bp(void *p) | |
692 | { | |
693 | return rcu_dereference_bp(p); | |
694 | } |