| 1 | /* |
| 2 | * Copyright (C) 2008-2011 Mathieu Desnoyers |
| 3 | * Copyright (C) 2009 Pierre-Marc Fournier |
| 4 | * |
| 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. |
| 9 | * |
| 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. |
| 14 | * |
| 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 |
| 18 | * |
| 19 | * Ported to userspace by Pierre-Marc Fournier. |
| 20 | */ |
| 21 | |
| 22 | #define _LGPL_SOURCE |
| 23 | #include <errno.h> |
| 24 | #include <ust/tracepoint.h> |
| 25 | #include <ust/tracepoint-internal.h> |
| 26 | #include <ust/core.h> |
| 27 | #include <ust/kcompat/kcompat.h> |
| 28 | #include <urcu-bp.h> |
| 29 | #include <urcu/hlist.h> |
| 30 | #include <urcu/uatomic.h> |
| 31 | |
| 32 | #include <ust/usterr-signal-safe.h> |
| 33 | |
| 34 | extern struct tracepoint * const __start___tracepoints_ptrs[] |
| 35 | __attribute__((visibility("hidden"))); |
| 36 | extern struct tracepoint * const __stop___tracepoints_ptrs[] |
| 37 | __attribute__((visibility("hidden"))); |
| 38 | |
| 39 | static struct tracepoint * __tracepoint_ptr_dummy |
| 40 | __attribute__((used, section("__tracepoints_ptrs"))); |
| 41 | |
| 42 | /* Set to 1 to enable tracepoint debug output */ |
| 43 | static const int tracepoint_debug; |
| 44 | static int initialized; |
| 45 | static void (*new_tracepoint_cb)(struct tracepoint *); |
| 46 | |
| 47 | /* libraries that contain tracepoints (struct tracepoint_lib) */ |
| 48 | static CDS_LIST_HEAD(libs); |
| 49 | |
| 50 | /* |
| 51 | * Allow nested mutex for mutex listing and nested enable. |
| 52 | */ |
| 53 | static __thread int nested_mutex; |
| 54 | |
| 55 | /* |
| 56 | * Tracepoints mutex protects the library tracepoints, the hash table, |
| 57 | * and the library list. |
| 58 | */ |
| 59 | static pthread_mutex_t tracepoints_mutex; |
| 60 | |
| 61 | static |
| 62 | void lock_tracepoints(void) |
| 63 | { |
| 64 | if (!(nested_mutex++)) |
| 65 | pthread_mutex_lock(&tracepoints_mutex); |
| 66 | } |
| 67 | |
| 68 | static |
| 69 | void unlock_tracepoints(void) |
| 70 | { |
| 71 | if (!(--nested_mutex)) |
| 72 | pthread_mutex_unlock(&tracepoints_mutex); |
| 73 | } |
| 74 | |
| 75 | /* |
| 76 | * Tracepoint hash table, containing the active tracepoints. |
| 77 | * Protected by tracepoints_mutex. |
| 78 | */ |
| 79 | #define TRACEPOINT_HASH_BITS 6 |
| 80 | #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) |
| 81 | static struct cds_hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; |
| 82 | |
| 83 | static CDS_LIST_HEAD(old_probes); |
| 84 | static int need_update; |
| 85 | |
| 86 | /* |
| 87 | * Note about RCU : |
| 88 | * It is used to to delay the free of multiple probes array until a quiescent |
| 89 | * state is reached. |
| 90 | * Tracepoint entries modifications are protected by the tracepoints_mutex. |
| 91 | */ |
| 92 | struct tracepoint_entry { |
| 93 | struct cds_hlist_node hlist; |
| 94 | struct tracepoint_probe *probes; |
| 95 | int refcount; /* Number of times armed. 0 if disarmed. */ |
| 96 | char name[0]; |
| 97 | }; |
| 98 | |
| 99 | struct tp_probes { |
| 100 | union { |
| 101 | struct cds_list_head list; |
| 102 | } u; |
| 103 | struct tracepoint_probe probes[0]; |
| 104 | }; |
| 105 | |
| 106 | static inline void *allocate_probes(int count) |
| 107 | { |
| 108 | struct tp_probes *p = zmalloc(count * sizeof(struct tracepoint_probe) |
| 109 | + sizeof(struct tp_probes)); |
| 110 | return p == NULL ? NULL : p->probes; |
| 111 | } |
| 112 | |
| 113 | static inline void release_probes(void *old) |
| 114 | { |
| 115 | if (old) { |
| 116 | struct tp_probes *tp_probes = _ust_container_of(old, |
| 117 | struct tp_probes, probes[0]); |
| 118 | synchronize_rcu(); |
| 119 | free(tp_probes); |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | static void debug_print_probes(struct tracepoint_entry *entry) |
| 124 | { |
| 125 | int i; |
| 126 | |
| 127 | if (!tracepoint_debug || !entry->probes) |
| 128 | return; |
| 129 | |
| 130 | for (i = 0; entry->probes[i].func; i++) |
| 131 | DBG("Probe %d : %p", i, entry->probes[i].func); |
| 132 | } |
| 133 | |
| 134 | static void * |
| 135 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, |
| 136 | void *probe, void *data) |
| 137 | { |
| 138 | int nr_probes = 0; |
| 139 | struct tracepoint_probe *old, *new; |
| 140 | |
| 141 | WARN_ON(!probe); |
| 142 | |
| 143 | debug_print_probes(entry); |
| 144 | old = entry->probes; |
| 145 | if (old) { |
| 146 | /* (N -> N+1), (N != 0, 1) probes */ |
| 147 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
| 148 | if (old[nr_probes].func == probe && |
| 149 | old[nr_probes].data == data) |
| 150 | return ERR_PTR(-EEXIST); |
| 151 | } |
| 152 | /* + 2 : one for new probe, one for NULL func */ |
| 153 | new = allocate_probes(nr_probes + 2); |
| 154 | if (new == NULL) |
| 155 | return ERR_PTR(-ENOMEM); |
| 156 | if (old) |
| 157 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_probe)); |
| 158 | new[nr_probes].func = probe; |
| 159 | new[nr_probes].data = data; |
| 160 | new[nr_probes + 1].func = NULL; |
| 161 | entry->refcount = nr_probes + 1; |
| 162 | entry->probes = new; |
| 163 | debug_print_probes(entry); |
| 164 | return old; |
| 165 | } |
| 166 | |
| 167 | static void * |
| 168 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe, |
| 169 | void *data) |
| 170 | { |
| 171 | int nr_probes = 0, nr_del = 0, i; |
| 172 | struct tracepoint_probe *old, *new; |
| 173 | |
| 174 | old = entry->probes; |
| 175 | |
| 176 | if (!old) |
| 177 | return ERR_PTR(-ENOENT); |
| 178 | |
| 179 | debug_print_probes(entry); |
| 180 | /* (N -> M), (N > 1, M >= 0) probes */ |
| 181 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { |
| 182 | if (!probe || |
| 183 | (old[nr_probes].func == probe && |
| 184 | old[nr_probes].data == data)) |
| 185 | nr_del++; |
| 186 | } |
| 187 | |
| 188 | if (nr_probes - nr_del == 0) { |
| 189 | /* N -> 0, (N > 1) */ |
| 190 | entry->probes = NULL; |
| 191 | entry->refcount = 0; |
| 192 | debug_print_probes(entry); |
| 193 | return old; |
| 194 | } else { |
| 195 | int j = 0; |
| 196 | /* N -> M, (N > 1, M > 0) */ |
| 197 | /* + 1 for NULL */ |
| 198 | new = allocate_probes(nr_probes - nr_del + 1); |
| 199 | if (new == NULL) |
| 200 | return ERR_PTR(-ENOMEM); |
| 201 | for (i = 0; old[i].func; i++) |
| 202 | if (probe && |
| 203 | (old[i].func != probe || old[i].data != data)) |
| 204 | new[j++] = old[i]; |
| 205 | new[nr_probes - nr_del].func = NULL; |
| 206 | entry->refcount = nr_probes - nr_del; |
| 207 | entry->probes = new; |
| 208 | } |
| 209 | debug_print_probes(entry); |
| 210 | return old; |
| 211 | } |
| 212 | |
| 213 | /* |
| 214 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. |
| 215 | * Must be called with tracepoints_mutex held. |
| 216 | * Returns NULL if not present. |
| 217 | */ |
| 218 | static struct tracepoint_entry *get_tracepoint(const char *name) |
| 219 | { |
| 220 | struct cds_hlist_head *head; |
| 221 | struct cds_hlist_node *node; |
| 222 | struct tracepoint_entry *e; |
| 223 | u32 hash = jhash(name, strlen(name), 0); |
| 224 | |
| 225 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
| 226 | cds_hlist_for_each_entry(e, node, head, hlist) { |
| 227 | if (!strcmp(name, e->name)) |
| 228 | return e; |
| 229 | } |
| 230 | return NULL; |
| 231 | } |
| 232 | |
| 233 | /* |
| 234 | * Add the tracepoint to the tracepoint hash table. Must be called with |
| 235 | * tracepoints_mutex held. |
| 236 | */ |
| 237 | static struct tracepoint_entry *add_tracepoint(const char *name) |
| 238 | { |
| 239 | struct cds_hlist_head *head; |
| 240 | struct cds_hlist_node *node; |
| 241 | struct tracepoint_entry *e; |
| 242 | size_t name_len = strlen(name) + 1; |
| 243 | u32 hash = jhash(name, name_len-1, 0); |
| 244 | |
| 245 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
| 246 | cds_hlist_for_each_entry(e, node, head, hlist) { |
| 247 | if (!strcmp(name, e->name)) { |
| 248 | DBG("tracepoint %s busy", name); |
| 249 | return ERR_PTR(-EEXIST); /* Already there */ |
| 250 | } |
| 251 | } |
| 252 | /* |
| 253 | * Using zmalloc here to allocate a variable length element. Could |
| 254 | * cause some memory fragmentation if overused. |
| 255 | */ |
| 256 | e = zmalloc(sizeof(struct tracepoint_entry) + name_len); |
| 257 | if (!e) |
| 258 | return ERR_PTR(-ENOMEM); |
| 259 | memcpy(&e->name[0], name, name_len); |
| 260 | e->probes = NULL; |
| 261 | e->refcount = 0; |
| 262 | cds_hlist_add_head(&e->hlist, head); |
| 263 | return e; |
| 264 | } |
| 265 | |
| 266 | /* |
| 267 | * Remove the tracepoint from the tracepoint hash table. Must be called with |
| 268 | * mutex_lock held. |
| 269 | */ |
| 270 | static inline void remove_tracepoint(struct tracepoint_entry *e) |
| 271 | { |
| 272 | cds_hlist_del(&e->hlist); |
| 273 | free(e); |
| 274 | } |
| 275 | |
| 276 | /* |
| 277 | * Sets the probe callback corresponding to one tracepoint. |
| 278 | */ |
| 279 | static void set_tracepoint(struct tracepoint_entry **entry, |
| 280 | struct tracepoint *elem, int active) |
| 281 | { |
| 282 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); |
| 283 | |
| 284 | /* |
| 285 | * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new |
| 286 | * probe callbacks array is consistent before setting a pointer to it. |
| 287 | * This array is referenced by __DO_TRACE from |
| 288 | * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends() |
| 289 | * is used. |
| 290 | */ |
| 291 | rcu_assign_pointer(elem->probes, (*entry)->probes); |
| 292 | elem->state = active; |
| 293 | } |
| 294 | |
| 295 | /* |
| 296 | * Disable a tracepoint and its probe callback. |
| 297 | * Note: only waiting an RCU period after setting elem->call to the empty |
| 298 | * function insures that the original callback is not used anymore. This insured |
| 299 | * by preempt_disable around the call site. |
| 300 | */ |
| 301 | static void disable_tracepoint(struct tracepoint *elem) |
| 302 | { |
| 303 | elem->state = 0; |
| 304 | rcu_assign_pointer(elem->probes, NULL); |
| 305 | } |
| 306 | |
| 307 | /** |
| 308 | * tracepoint_update_probe_range - Update a probe range |
| 309 | * @begin: beginning of the range |
| 310 | * @end: end of the range |
| 311 | * |
| 312 | * Updates the probe callback corresponding to a range of tracepoints. |
| 313 | */ |
| 314 | static |
| 315 | void tracepoint_update_probe_range(struct tracepoint * const *begin, |
| 316 | struct tracepoint * const *end) |
| 317 | { |
| 318 | struct tracepoint * const *iter; |
| 319 | struct tracepoint_entry *mark_entry; |
| 320 | |
| 321 | for (iter = begin; iter < end; iter++) { |
| 322 | if (!*iter) |
| 323 | continue; /* skip dummy */ |
| 324 | if (!(*iter)->name) { |
| 325 | disable_tracepoint(*iter); |
| 326 | continue; |
| 327 | } |
| 328 | mark_entry = get_tracepoint((*iter)->name); |
| 329 | if (mark_entry) { |
| 330 | set_tracepoint(&mark_entry, *iter, |
| 331 | !!mark_entry->refcount); |
| 332 | } else { |
| 333 | disable_tracepoint(*iter); |
| 334 | } |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | static void lib_update_tracepoints(void) |
| 339 | { |
| 340 | struct tracepoint_lib *lib; |
| 341 | |
| 342 | lock_tracepoints(); |
| 343 | cds_list_for_each_entry(lib, &libs, list) { |
| 344 | tracepoint_update_probe_range(lib->tracepoints_start, |
| 345 | lib->tracepoints_start + lib->tracepoints_count); |
| 346 | } |
| 347 | unlock_tracepoints(); |
| 348 | } |
| 349 | |
| 350 | /* |
| 351 | * Update probes, removing the faulty probes. |
| 352 | */ |
| 353 | static void tracepoint_update_probes(void) |
| 354 | { |
| 355 | /* tracepoints registered from libraries and executable. */ |
| 356 | lib_update_tracepoints(); |
| 357 | } |
| 358 | |
| 359 | static struct tracepoint_probe * |
| 360 | tracepoint_add_probe(const char *name, void *probe, void *data) |
| 361 | { |
| 362 | struct tracepoint_entry *entry; |
| 363 | struct tracepoint_probe *old; |
| 364 | |
| 365 | entry = get_tracepoint(name); |
| 366 | if (!entry) { |
| 367 | entry = add_tracepoint(name); |
| 368 | if (IS_ERR(entry)) |
| 369 | return (struct tracepoint_probe *)entry; |
| 370 | } |
| 371 | old = tracepoint_entry_add_probe(entry, probe, data); |
| 372 | if (IS_ERR(old) && !entry->refcount) |
| 373 | remove_tracepoint(entry); |
| 374 | return old; |
| 375 | } |
| 376 | |
| 377 | /** |
| 378 | * __tracepoint_probe_register - Connect a probe to a tracepoint |
| 379 | * @name: tracepoint name |
| 380 | * @probe: probe handler |
| 381 | * |
| 382 | * Returns 0 if ok, error value on error. |
| 383 | * The probe address must at least be aligned on the architecture pointer size. |
| 384 | */ |
| 385 | int __tracepoint_probe_register(const char *name, void *probe, void *data) |
| 386 | { |
| 387 | void *old; |
| 388 | |
| 389 | lock_tracepoints(); |
| 390 | old = tracepoint_add_probe(name, probe, data); |
| 391 | unlock_tracepoints(); |
| 392 | if (IS_ERR(old)) |
| 393 | return PTR_ERR(old); |
| 394 | |
| 395 | tracepoint_update_probes(); /* may update entry */ |
| 396 | release_probes(old); |
| 397 | return 0; |
| 398 | } |
| 399 | |
| 400 | static void *tracepoint_remove_probe(const char *name, void *probe, void *data) |
| 401 | { |
| 402 | struct tracepoint_entry *entry; |
| 403 | void *old; |
| 404 | |
| 405 | entry = get_tracepoint(name); |
| 406 | if (!entry) |
| 407 | return ERR_PTR(-ENOENT); |
| 408 | old = tracepoint_entry_remove_probe(entry, probe, data); |
| 409 | if (IS_ERR(old)) |
| 410 | return old; |
| 411 | if (!entry->refcount) |
| 412 | remove_tracepoint(entry); |
| 413 | return old; |
| 414 | } |
| 415 | |
| 416 | /** |
| 417 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint |
| 418 | * @name: tracepoint name |
| 419 | * @probe: probe function pointer |
| 420 | * @probe: probe data pointer |
| 421 | * |
| 422 | * We do not need to call a synchronize_sched to make sure the probes have |
| 423 | * finished running before doing a module unload, because the module unload |
| 424 | * itself uses stop_machine(), which insures that every preempt disabled section |
| 425 | * have finished. |
| 426 | */ |
| 427 | int __tracepoint_probe_unregister(const char *name, void *probe, void *data) |
| 428 | { |
| 429 | void *old; |
| 430 | |
| 431 | lock_tracepoints(); |
| 432 | old = tracepoint_remove_probe(name, probe, data); |
| 433 | unlock_tracepoints(); |
| 434 | if (IS_ERR(old)) |
| 435 | return PTR_ERR(old); |
| 436 | |
| 437 | tracepoint_update_probes(); /* may update entry */ |
| 438 | release_probes(old); |
| 439 | return 0; |
| 440 | } |
| 441 | |
| 442 | static void tracepoint_add_old_probes(void *old) |
| 443 | { |
| 444 | need_update = 1; |
| 445 | if (old) { |
| 446 | struct tp_probes *tp_probes = _ust_container_of(old, |
| 447 | struct tp_probes, probes[0]); |
| 448 | cds_list_add(&tp_probes->u.list, &old_probes); |
| 449 | } |
| 450 | } |
| 451 | |
| 452 | /** |
| 453 | * tracepoint_probe_register_noupdate - register a probe but not connect |
| 454 | * @name: tracepoint name |
| 455 | * @probe: probe handler |
| 456 | * |
| 457 | * caller must call tracepoint_probe_update_all() |
| 458 | */ |
| 459 | int tracepoint_probe_register_noupdate(const char *name, void *probe, |
| 460 | void *data) |
| 461 | { |
| 462 | void *old; |
| 463 | |
| 464 | lock_tracepoints(); |
| 465 | old = tracepoint_add_probe(name, probe, data); |
| 466 | if (IS_ERR(old)) { |
| 467 | unlock_tracepoints(); |
| 468 | return PTR_ERR(old); |
| 469 | } |
| 470 | tracepoint_add_old_probes(old); |
| 471 | unlock_tracepoints(); |
| 472 | return 0; |
| 473 | } |
| 474 | |
| 475 | /** |
| 476 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect |
| 477 | * @name: tracepoint name |
| 478 | * @probe: probe function pointer |
| 479 | * |
| 480 | * caller must call tracepoint_probe_update_all() |
| 481 | */ |
| 482 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe, |
| 483 | void *data) |
| 484 | { |
| 485 | void *old; |
| 486 | |
| 487 | lock_tracepoints(); |
| 488 | old = tracepoint_remove_probe(name, probe, data); |
| 489 | if (IS_ERR(old)) { |
| 490 | unlock_tracepoints(); |
| 491 | return PTR_ERR(old); |
| 492 | } |
| 493 | tracepoint_add_old_probes(old); |
| 494 | unlock_tracepoints(); |
| 495 | return 0; |
| 496 | } |
| 497 | |
| 498 | /** |
| 499 | * tracepoint_probe_update_all - update tracepoints |
| 500 | */ |
| 501 | void tracepoint_probe_update_all(void) |
| 502 | { |
| 503 | CDS_LIST_HEAD(release_probes); |
| 504 | struct tp_probes *pos, *next; |
| 505 | |
| 506 | lock_tracepoints(); |
| 507 | if (!need_update) { |
| 508 | unlock_tracepoints(); |
| 509 | return; |
| 510 | } |
| 511 | if (!cds_list_empty(&old_probes)) |
| 512 | cds_list_replace_init(&old_probes, &release_probes); |
| 513 | need_update = 0; |
| 514 | unlock_tracepoints(); |
| 515 | |
| 516 | tracepoint_update_probes(); |
| 517 | cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
| 518 | cds_list_del(&pos->u.list); |
| 519 | synchronize_rcu(); |
| 520 | free(pos); |
| 521 | } |
| 522 | } |
| 523 | |
| 524 | /* |
| 525 | * Returns 0 if current not found. |
| 526 | * Returns 1 if current found. |
| 527 | * |
| 528 | * Called with tracepoint mutex held |
| 529 | */ |
| 530 | int lib_get_iter_tracepoints(struct tracepoint_iter *iter) |
| 531 | { |
| 532 | struct tracepoint_lib *iter_lib; |
| 533 | int found = 0; |
| 534 | |
| 535 | cds_list_for_each_entry(iter_lib, &libs, list) { |
| 536 | if (iter_lib < iter->lib) |
| 537 | continue; |
| 538 | else if (iter_lib > iter->lib) |
| 539 | iter->tracepoint = NULL; |
| 540 | found = tracepoint_get_iter_range(&iter->tracepoint, |
| 541 | iter_lib->tracepoints_start, |
| 542 | iter_lib->tracepoints_start + iter_lib->tracepoints_count); |
| 543 | if (found) { |
| 544 | iter->lib = iter_lib; |
| 545 | break; |
| 546 | } |
| 547 | } |
| 548 | return found; |
| 549 | } |
| 550 | |
| 551 | /** |
| 552 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. |
| 553 | * @tracepoint: current tracepoints (in), next tracepoint (out) |
| 554 | * @begin: beginning of the range |
| 555 | * @end: end of the range |
| 556 | * |
| 557 | * Returns whether a next tracepoint has been found (1) or not (0). |
| 558 | * Will return the first tracepoint in the range if the input tracepoint is |
| 559 | * NULL. |
| 560 | * Called with tracepoint mutex held. |
| 561 | */ |
| 562 | int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, |
| 563 | struct tracepoint * const *begin, struct tracepoint * const *end) |
| 564 | { |
| 565 | if (!*tracepoint && begin != end) |
| 566 | *tracepoint = begin; |
| 567 | while (*tracepoint >= begin && *tracepoint < end) { |
| 568 | if (!**tracepoint) |
| 569 | (*tracepoint)++; /* skip dummy */ |
| 570 | else |
| 571 | return 1; |
| 572 | } |
| 573 | return 0; |
| 574 | } |
| 575 | |
| 576 | /* |
| 577 | * Called with tracepoint mutex held. |
| 578 | */ |
| 579 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
| 580 | { |
| 581 | int found = 0; |
| 582 | |
| 583 | /* tracepoints in libs. */ |
| 584 | found = lib_get_iter_tracepoints(iter); |
| 585 | if (!found) |
| 586 | tracepoint_iter_reset(iter); |
| 587 | } |
| 588 | |
| 589 | void tracepoint_iter_start(struct tracepoint_iter *iter) |
| 590 | { |
| 591 | lock_tracepoints(); |
| 592 | tracepoint_get_iter(iter); |
| 593 | } |
| 594 | |
| 595 | /* |
| 596 | * Called with tracepoint mutex held. |
| 597 | */ |
| 598 | void tracepoint_iter_next(struct tracepoint_iter *iter) |
| 599 | { |
| 600 | iter->tracepoint++; |
| 601 | /* |
| 602 | * iter->tracepoint may be invalid because we blindly incremented it. |
| 603 | * Make sure it is valid by marshalling on the tracepoints, getting the |
| 604 | * tracepoints from following modules if necessary. |
| 605 | */ |
| 606 | tracepoint_get_iter(iter); |
| 607 | } |
| 608 | |
| 609 | void tracepoint_iter_stop(struct tracepoint_iter *iter) |
| 610 | { |
| 611 | unlock_tracepoints(); |
| 612 | } |
| 613 | |
| 614 | void tracepoint_iter_reset(struct tracepoint_iter *iter) |
| 615 | { |
| 616 | iter->tracepoint = NULL; |
| 617 | } |
| 618 | |
| 619 | void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *)) |
| 620 | { |
| 621 | new_tracepoint_cb = cb; |
| 622 | } |
| 623 | |
| 624 | static void new_tracepoints(struct tracepoint * const *start, struct tracepoint * const *end) |
| 625 | { |
| 626 | if (new_tracepoint_cb) { |
| 627 | struct tracepoint * const *t; |
| 628 | |
| 629 | for (t = start; t < end; t++) { |
| 630 | if (*t) |
| 631 | new_tracepoint_cb(*t); |
| 632 | } |
| 633 | } |
| 634 | } |
| 635 | |
| 636 | int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, |
| 637 | int tracepoints_count) |
| 638 | { |
| 639 | struct tracepoint_lib *pl, *iter; |
| 640 | |
| 641 | init_tracepoint(); |
| 642 | |
| 643 | pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib)); |
| 644 | |
| 645 | pl->tracepoints_start = tracepoints_start; |
| 646 | pl->tracepoints_count = tracepoints_count; |
| 647 | |
| 648 | lock_tracepoints(); |
| 649 | /* |
| 650 | * We sort the libs by struct lib pointer address. |
| 651 | */ |
| 652 | cds_list_for_each_entry_reverse(iter, &libs, list) { |
| 653 | BUG_ON(iter == pl); /* Should never be in the list twice */ |
| 654 | if (iter < pl) { |
| 655 | /* We belong to the location right after iter. */ |
| 656 | cds_list_add(&pl->list, &iter->list); |
| 657 | goto lib_added; |
| 658 | } |
| 659 | } |
| 660 | /* We should be added at the head of the list */ |
| 661 | cds_list_add(&pl->list, &libs); |
| 662 | lib_added: |
| 663 | unlock_tracepoints(); |
| 664 | |
| 665 | new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count); |
| 666 | |
| 667 | /* TODO: update just the loaded lib */ |
| 668 | lib_update_tracepoints(); |
| 669 | |
| 670 | /* tracepoints_count - 1: skip dummy */ |
| 671 | DBG("just registered a tracepoints section from %p and having %d tracepoints (minus dummy tracepoints)", tracepoints_start, tracepoints_count); |
| 672 | |
| 673 | return 0; |
| 674 | } |
| 675 | |
| 676 | int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start) |
| 677 | { |
| 678 | struct tracepoint_lib *lib; |
| 679 | |
| 680 | lock_tracepoints(); |
| 681 | cds_list_for_each_entry(lib, &libs, list) { |
| 682 | if (lib->tracepoints_start == tracepoints_start) { |
| 683 | struct tracepoint_lib *lib2free = lib; |
| 684 | cds_list_del(&lib->list); |
| 685 | free(lib2free); |
| 686 | break; |
| 687 | } |
| 688 | } |
| 689 | unlock_tracepoints(); |
| 690 | |
| 691 | return 0; |
| 692 | } |
| 693 | |
| 694 | void init_tracepoint(void) |
| 695 | { |
| 696 | if (uatomic_xchg(&initialized, 1) == 1) |
| 697 | return; |
| 698 | init_usterr(); |
| 699 | tracepoint_register_lib(__start___tracepoints_ptrs, |
| 700 | __stop___tracepoints_ptrs |
| 701 | - __start___tracepoints_ptrs); |
| 702 | } |
| 703 | |
| 704 | void exit_tracepoint(void) |
| 705 | { |
| 706 | tracepoint_unregister_lib(__start___tracepoints_ptrs); |
| 707 | } |