| 1 | /* |
| 2 | * Copyright (C) 2008 Mathieu Desnoyers |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | */ |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/mutex.h> |
| 20 | #include <linux/types.h> |
| 21 | #include <linux/jhash.h> |
| 22 | #include <linux/list.h> |
| 23 | #include <linux/rcupdate.h> |
| 24 | #include <linux/tracepoint.h> |
| 25 | #include <linux/err.h> |
| 26 | #include <linux/slab.h> |
| 27 | #include <linux/sched.h> |
| 28 | #include <linux/static_key.h> |
| 29 | |
| 30 | extern struct tracepoint * const __start___tracepoints_ptrs[]; |
| 31 | extern struct tracepoint * const __stop___tracepoints_ptrs[]; |
| 32 | |
| 33 | /* Set to 1 to enable tracepoint debug output */ |
| 34 | static const int tracepoint_debug; |
| 35 | |
| 36 | /* |
| 37 | * Tracepoints mutex protects the builtin and module tracepoints and the hash |
| 38 | * table, as well as the local module list. |
| 39 | */ |
| 40 | static DEFINE_MUTEX(tracepoints_mutex); |
| 41 | |
| 42 | #ifdef CONFIG_MODULES |
| 43 | /* Local list of struct module */ |
| 44 | static LIST_HEAD(tracepoint_module_list); |
| 45 | #endif /* CONFIG_MODULES */ |
| 46 | |
| 47 | /* |
| 48 | * Tracepoint hash table, containing the active tracepoints. |
| 49 | * Protected by tracepoints_mutex. |
| 50 | */ |
| 51 | #define TRACEPOINT_HASH_BITS 6 |
| 52 | #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) |
| 53 | static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; |
| 54 | |
| 55 | /* |
| 56 | * Note about RCU : |
| 57 | * It is used to delay the free of multiple probes array until a quiescent |
| 58 | * state is reached. |
| 59 | * Tracepoint entries modifications are protected by the tracepoints_mutex. |
| 60 | */ |
| 61 | struct tracepoint_entry { |
| 62 | struct hlist_node hlist; |
| 63 | struct tracepoint_func *funcs; |
| 64 | int refcount; /* Number of times armed. 0 if disarmed. */ |
| 65 | char name[0]; |
| 66 | }; |
| 67 | |
| 68 | struct tp_probes { |
| 69 | union { |
| 70 | struct rcu_head rcu; |
| 71 | struct list_head list; |
| 72 | } u; |
| 73 | struct tracepoint_func probes[0]; |
| 74 | }; |
| 75 | |
| 76 | static inline void *allocate_probes(int count) |
| 77 | { |
| 78 | struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) |
| 79 | + sizeof(struct tp_probes), GFP_KERNEL); |
| 80 | return p == NULL ? NULL : p->probes; |
| 81 | } |
| 82 | |
| 83 | static void rcu_free_old_probes(struct rcu_head *head) |
| 84 | { |
| 85 | kfree(container_of(head, struct tp_probes, u.rcu)); |
| 86 | } |
| 87 | |
| 88 | static inline void release_probes(struct tracepoint_func *old) |
| 89 | { |
| 90 | if (old) { |
| 91 | struct tp_probes *tp_probes = container_of(old, |
| 92 | struct tp_probes, probes[0]); |
| 93 | call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes); |
| 94 | } |
| 95 | } |
| 96 | |
| 97 | static void debug_print_probes(struct tracepoint_entry *entry) |
| 98 | { |
| 99 | int i; |
| 100 | |
| 101 | if (!tracepoint_debug || !entry->funcs) |
| 102 | return; |
| 103 | |
| 104 | for (i = 0; entry->funcs[i].func; i++) |
| 105 | printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func); |
| 106 | } |
| 107 | |
| 108 | static struct tracepoint_func * |
| 109 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, |
| 110 | void *probe, void *data) |
| 111 | { |
| 112 | int nr_probes = 0; |
| 113 | struct tracepoint_func *old, *new; |
| 114 | |
| 115 | WARN_ON(!probe); |
| 116 | |
| 117 | debug_print_probes(entry); |
| 118 | old = entry->funcs; |
| 119 | if (old) { |
| 120 | /* (N -> N+1), (N != 0, 1) probes */ |
| 121 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
| 122 | if (old[nr_probes].func == probe && |
| 123 | old[nr_probes].data == data) |
| 124 | return ERR_PTR(-EEXIST); |
| 125 | } |
| 126 | /* + 2 : one for new probe, one for NULL func */ |
| 127 | new = allocate_probes(nr_probes + 2); |
| 128 | if (new == NULL) |
| 129 | return ERR_PTR(-ENOMEM); |
| 130 | if (old) |
| 131 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); |
| 132 | new[nr_probes].func = probe; |
| 133 | new[nr_probes].data = data; |
| 134 | new[nr_probes + 1].func = NULL; |
| 135 | entry->refcount = nr_probes + 1; |
| 136 | entry->funcs = new; |
| 137 | debug_print_probes(entry); |
| 138 | return old; |
| 139 | } |
| 140 | |
| 141 | static void * |
| 142 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, |
| 143 | void *probe, void *data) |
| 144 | { |
| 145 | int nr_probes = 0, nr_del = 0, i; |
| 146 | struct tracepoint_func *old, *new; |
| 147 | |
| 148 | old = entry->funcs; |
| 149 | |
| 150 | if (!old) |
| 151 | return ERR_PTR(-ENOENT); |
| 152 | |
| 153 | debug_print_probes(entry); |
| 154 | /* (N -> M), (N > 1, M >= 0) probes */ |
| 155 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { |
| 156 | if (!probe || |
| 157 | (old[nr_probes].func == probe && |
| 158 | old[nr_probes].data == data)) |
| 159 | nr_del++; |
| 160 | } |
| 161 | |
| 162 | if (nr_probes - nr_del == 0) { |
| 163 | /* N -> 0, (N > 1) */ |
| 164 | entry->funcs = NULL; |
| 165 | entry->refcount = 0; |
| 166 | debug_print_probes(entry); |
| 167 | return old; |
| 168 | } else { |
| 169 | int j = 0; |
| 170 | /* N -> M, (N > 1, M > 0) */ |
| 171 | /* + 1 for NULL */ |
| 172 | new = allocate_probes(nr_probes - nr_del + 1); |
| 173 | if (new == NULL) |
| 174 | return ERR_PTR(-ENOMEM); |
| 175 | for (i = 0; old[i].func; i++) |
| 176 | if (probe && |
| 177 | (old[i].func != probe || old[i].data != data)) |
| 178 | new[j++] = old[i]; |
| 179 | new[nr_probes - nr_del].func = NULL; |
| 180 | entry->refcount = nr_probes - nr_del; |
| 181 | entry->funcs = new; |
| 182 | } |
| 183 | debug_print_probes(entry); |
| 184 | return old; |
| 185 | } |
| 186 | |
| 187 | /* |
| 188 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. |
| 189 | * Must be called with tracepoints_mutex held. |
| 190 | * Returns NULL if not present. |
| 191 | */ |
| 192 | static struct tracepoint_entry *get_tracepoint(const char *name) |
| 193 | { |
| 194 | struct hlist_head *head; |
| 195 | struct hlist_node *node; |
| 196 | struct tracepoint_entry *e; |
| 197 | u32 hash = jhash(name, strlen(name), 0); |
| 198 | |
| 199 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
| 200 | hlist_for_each_entry(e, node, head, hlist) { |
| 201 | if (!strcmp(name, e->name)) |
| 202 | return e; |
| 203 | } |
| 204 | return NULL; |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * Add the tracepoint to the tracepoint hash table. Must be called with |
| 209 | * tracepoints_mutex held. |
| 210 | */ |
| 211 | static struct tracepoint_entry *add_tracepoint(const char *name) |
| 212 | { |
| 213 | struct hlist_head *head; |
| 214 | struct hlist_node *node; |
| 215 | struct tracepoint_entry *e; |
| 216 | size_t name_len = strlen(name) + 1; |
| 217 | u32 hash = jhash(name, name_len-1, 0); |
| 218 | |
| 219 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
| 220 | hlist_for_each_entry(e, node, head, hlist) { |
| 221 | if (!strcmp(name, e->name)) { |
| 222 | printk(KERN_NOTICE |
| 223 | "tracepoint %s busy\n", name); |
| 224 | return ERR_PTR(-EEXIST); /* Already there */ |
| 225 | } |
| 226 | } |
| 227 | /* |
| 228 | * Using kmalloc here to allocate a variable length element. Could |
| 229 | * cause some memory fragmentation if overused. |
| 230 | */ |
| 231 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); |
| 232 | if (!e) |
| 233 | return ERR_PTR(-ENOMEM); |
| 234 | memcpy(&e->name[0], name, name_len); |
| 235 | e->funcs = NULL; |
| 236 | e->refcount = 0; |
| 237 | hlist_add_head(&e->hlist, head); |
| 238 | return e; |
| 239 | } |
| 240 | |
| 241 | /* |
| 242 | * Remove the tracepoint from the tracepoint hash table. Must be called with |
| 243 | * mutex_lock held. |
| 244 | */ |
| 245 | static inline void remove_tracepoint(struct tracepoint_entry *e) |
| 246 | { |
| 247 | hlist_del(&e->hlist); |
| 248 | kfree(e); |
| 249 | } |
| 250 | |
| 251 | /* |
| 252 | * Sets the probe callback corresponding to one tracepoint. |
| 253 | */ |
| 254 | static void set_tracepoint(struct tracepoint_entry **entry, |
| 255 | struct tracepoint *elem, int active) |
| 256 | { |
| 257 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); |
| 258 | |
| 259 | if (elem->regfunc && !static_key_enabled(&elem->key) && active) |
| 260 | elem->regfunc(); |
| 261 | else if (elem->unregfunc && static_key_enabled(&elem->key) && !active) |
| 262 | elem->unregfunc(); |
| 263 | |
| 264 | /* |
| 265 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new |
| 266 | * probe callbacks array is consistent before setting a pointer to it. |
| 267 | * This array is referenced by __DO_TRACE from |
| 268 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() |
| 269 | * is used. |
| 270 | */ |
| 271 | rcu_assign_pointer(elem->funcs, (*entry)->funcs); |
| 272 | if (active && !static_key_enabled(&elem->key)) |
| 273 | static_key_slow_inc(&elem->key); |
| 274 | else if (!active && static_key_enabled(&elem->key)) |
| 275 | static_key_slow_dec(&elem->key); |
| 276 | } |
| 277 | |
| 278 | /* |
| 279 | * Disable a tracepoint and its probe callback. |
| 280 | * Note: only waiting an RCU period after setting elem->call to the empty |
| 281 | * function insures that the original callback is not used anymore. This insured |
| 282 | * by preempt_disable around the call site. |
| 283 | */ |
| 284 | static void disable_tracepoint(struct tracepoint *elem) |
| 285 | { |
| 286 | if (elem->unregfunc && static_key_enabled(&elem->key)) |
| 287 | elem->unregfunc(); |
| 288 | |
| 289 | if (static_key_enabled(&elem->key)) |
| 290 | static_key_slow_dec(&elem->key); |
| 291 | rcu_assign_pointer(elem->funcs, NULL); |
| 292 | } |
| 293 | |
| 294 | /** |
| 295 | * tracepoint_update_probe_range - Update a probe range |
| 296 | * @begin: beginning of the range |
| 297 | * @end: end of the range |
| 298 | * |
| 299 | * Updates the probe callback corresponding to a range of tracepoints. |
| 300 | * Called with tracepoints_mutex held. |
| 301 | */ |
| 302 | static void tracepoint_update_probe_range(struct tracepoint * const *begin, |
| 303 | struct tracepoint * const *end) |
| 304 | { |
| 305 | struct tracepoint * const *iter; |
| 306 | struct tracepoint_entry *mark_entry; |
| 307 | |
| 308 | if (!begin) |
| 309 | return; |
| 310 | |
| 311 | for (iter = begin; iter < end; iter++) { |
| 312 | mark_entry = get_tracepoint((*iter)->name); |
| 313 | if (mark_entry) { |
| 314 | set_tracepoint(&mark_entry, *iter, |
| 315 | !!mark_entry->refcount); |
| 316 | } else { |
| 317 | disable_tracepoint(*iter); |
| 318 | } |
| 319 | } |
| 320 | } |
| 321 | |
| 322 | #ifdef CONFIG_MODULES |
| 323 | void module_update_tracepoints(void) |
| 324 | { |
| 325 | struct tp_module *tp_mod; |
| 326 | |
| 327 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) |
| 328 | tracepoint_update_probe_range(tp_mod->tracepoints_ptrs, |
| 329 | tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints); |
| 330 | } |
| 331 | #else /* CONFIG_MODULES */ |
| 332 | void module_update_tracepoints(void) |
| 333 | { |
| 334 | } |
| 335 | #endif /* CONFIG_MODULES */ |
| 336 | |
| 337 | |
| 338 | /* |
| 339 | * Update probes, removing the faulty probes. |
| 340 | * Called with tracepoints_mutex held. |
| 341 | */ |
| 342 | static void tracepoint_update_probes(void) |
| 343 | { |
| 344 | /* Core kernel tracepoints */ |
| 345 | tracepoint_update_probe_range(__start___tracepoints_ptrs, |
| 346 | __stop___tracepoints_ptrs); |
| 347 | /* tracepoints in modules. */ |
| 348 | module_update_tracepoints(); |
| 349 | } |
| 350 | |
| 351 | static struct tracepoint_func * |
| 352 | tracepoint_add_probe(const char *name, void *probe, void *data) |
| 353 | { |
| 354 | struct tracepoint_entry *entry; |
| 355 | struct tracepoint_func *old; |
| 356 | |
| 357 | entry = get_tracepoint(name); |
| 358 | if (!entry) { |
| 359 | entry = add_tracepoint(name); |
| 360 | if (IS_ERR(entry)) |
| 361 | return (struct tracepoint_func *)entry; |
| 362 | } |
| 363 | old = tracepoint_entry_add_probe(entry, probe, data); |
| 364 | if (IS_ERR(old) && !entry->refcount) |
| 365 | remove_tracepoint(entry); |
| 366 | return old; |
| 367 | } |
| 368 | |
| 369 | /** |
| 370 | * tracepoint_probe_register - Connect a probe to a tracepoint |
| 371 | * @name: tracepoint name |
| 372 | * @probe: probe handler |
| 373 | * |
| 374 | * Returns 0 if ok, error value on error. |
| 375 | * The probe address must at least be aligned on the architecture pointer size. |
| 376 | */ |
| 377 | int tracepoint_probe_register(const char *name, void *probe, void *data) |
| 378 | { |
| 379 | struct tracepoint_func *old; |
| 380 | |
| 381 | mutex_lock(&tracepoints_mutex); |
| 382 | old = tracepoint_add_probe(name, probe, data); |
| 383 | if (IS_ERR(old)) { |
| 384 | mutex_unlock(&tracepoints_mutex); |
| 385 | return PTR_ERR(old); |
| 386 | } |
| 387 | tracepoint_update_probes(); /* may update entry */ |
| 388 | mutex_unlock(&tracepoints_mutex); |
| 389 | release_probes(old); |
| 390 | return 0; |
| 391 | } |
| 392 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); |
| 393 | |
| 394 | static struct tracepoint_func * |
| 395 | tracepoint_remove_probe(const char *name, void *probe, void *data) |
| 396 | { |
| 397 | struct tracepoint_entry *entry; |
| 398 | struct tracepoint_func *old; |
| 399 | |
| 400 | entry = get_tracepoint(name); |
| 401 | if (!entry) |
| 402 | return ERR_PTR(-ENOENT); |
| 403 | old = tracepoint_entry_remove_probe(entry, probe, data); |
| 404 | if (IS_ERR(old)) |
| 405 | return old; |
| 406 | if (!entry->refcount) |
| 407 | remove_tracepoint(entry); |
| 408 | return old; |
| 409 | } |
| 410 | |
| 411 | /** |
| 412 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint |
| 413 | * @name: tracepoint name |
| 414 | * @probe: probe function pointer |
| 415 | * |
| 416 | * We do not need to call a synchronize_sched to make sure the probes have |
| 417 | * finished running before doing a module unload, because the module unload |
| 418 | * itself uses stop_machine(), which insures that every preempt disabled section |
| 419 | * have finished. |
| 420 | */ |
| 421 | int tracepoint_probe_unregister(const char *name, void *probe, void *data) |
| 422 | { |
| 423 | struct tracepoint_func *old; |
| 424 | |
| 425 | mutex_lock(&tracepoints_mutex); |
| 426 | old = tracepoint_remove_probe(name, probe, data); |
| 427 | if (IS_ERR(old)) { |
| 428 | mutex_unlock(&tracepoints_mutex); |
| 429 | return PTR_ERR(old); |
| 430 | } |
| 431 | tracepoint_update_probes(); /* may update entry */ |
| 432 | mutex_unlock(&tracepoints_mutex); |
| 433 | release_probes(old); |
| 434 | return 0; |
| 435 | } |
| 436 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); |
| 437 | |
| 438 | static LIST_HEAD(old_probes); |
| 439 | static int need_update; |
| 440 | |
| 441 | static void tracepoint_add_old_probes(void *old) |
| 442 | { |
| 443 | need_update = 1; |
| 444 | if (old) { |
| 445 | struct tp_probes *tp_probes = container_of(old, |
| 446 | struct tp_probes, probes[0]); |
| 447 | list_add(&tp_probes->u.list, &old_probes); |
| 448 | } |
| 449 | } |
| 450 | |
| 451 | /** |
| 452 | * tracepoint_probe_register_noupdate - register a probe but not connect |
| 453 | * @name: tracepoint name |
| 454 | * @probe: probe handler |
| 455 | * |
| 456 | * caller must call tracepoint_probe_update_all() |
| 457 | */ |
| 458 | int tracepoint_probe_register_noupdate(const char *name, void *probe, |
| 459 | void *data) |
| 460 | { |
| 461 | struct tracepoint_func *old; |
| 462 | |
| 463 | mutex_lock(&tracepoints_mutex); |
| 464 | old = tracepoint_add_probe(name, probe, data); |
| 465 | if (IS_ERR(old)) { |
| 466 | mutex_unlock(&tracepoints_mutex); |
| 467 | return PTR_ERR(old); |
| 468 | } |
| 469 | tracepoint_add_old_probes(old); |
| 470 | mutex_unlock(&tracepoints_mutex); |
| 471 | return 0; |
| 472 | } |
| 473 | EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); |
| 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 | struct tracepoint_func *old; |
| 486 | |
| 487 | mutex_lock(&tracepoints_mutex); |
| 488 | old = tracepoint_remove_probe(name, probe, data); |
| 489 | if (IS_ERR(old)) { |
| 490 | mutex_unlock(&tracepoints_mutex); |
| 491 | return PTR_ERR(old); |
| 492 | } |
| 493 | tracepoint_add_old_probes(old); |
| 494 | mutex_unlock(&tracepoints_mutex); |
| 495 | return 0; |
| 496 | } |
| 497 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); |
| 498 | |
| 499 | /** |
| 500 | * tracepoint_probe_update_all - update tracepoints |
| 501 | */ |
| 502 | void tracepoint_probe_update_all(void) |
| 503 | { |
| 504 | LIST_HEAD(release_probes); |
| 505 | struct tp_probes *pos, *next; |
| 506 | |
| 507 | mutex_lock(&tracepoints_mutex); |
| 508 | if (!need_update) { |
| 509 | mutex_unlock(&tracepoints_mutex); |
| 510 | return; |
| 511 | } |
| 512 | if (!list_empty(&old_probes)) |
| 513 | list_replace_init(&old_probes, &release_probes); |
| 514 | need_update = 0; |
| 515 | tracepoint_update_probes(); |
| 516 | mutex_unlock(&tracepoints_mutex); |
| 517 | list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
| 518 | list_del(&pos->u.list); |
| 519 | call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); |
| 520 | } |
| 521 | } |
| 522 | EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); |
| 523 | |
| 524 | /** |
| 525 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. |
| 526 | * @tracepoint: current tracepoints (in), next tracepoint (out) |
| 527 | * @begin: beginning of the range |
| 528 | * @end: end of the range |
| 529 | * |
| 530 | * Returns whether a next tracepoint has been found (1) or not (0). |
| 531 | * Will return the first tracepoint in the range if the input tracepoint is |
| 532 | * NULL. |
| 533 | */ |
| 534 | static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, |
| 535 | struct tracepoint * const *begin, struct tracepoint * const *end) |
| 536 | { |
| 537 | if (!*tracepoint && begin != end) { |
| 538 | *tracepoint = begin; |
| 539 | return 1; |
| 540 | } |
| 541 | if (*tracepoint >= begin && *tracepoint < end) |
| 542 | return 1; |
| 543 | return 0; |
| 544 | } |
| 545 | |
| 546 | #ifdef CONFIG_MODULES |
| 547 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
| 548 | { |
| 549 | int found = 0; |
| 550 | struct tp_module *iter_mod; |
| 551 | |
| 552 | /* Core kernel tracepoints */ |
| 553 | if (!iter->module) { |
| 554 | found = tracepoint_get_iter_range(&iter->tracepoint, |
| 555 | __start___tracepoints_ptrs, |
| 556 | __stop___tracepoints_ptrs); |
| 557 | if (found) |
| 558 | goto end; |
| 559 | } |
| 560 | /* Tracepoints in modules */ |
| 561 | mutex_lock(&tracepoints_mutex); |
| 562 | list_for_each_entry(iter_mod, &tracepoint_module_list, list) { |
| 563 | /* |
| 564 | * Sorted module list |
| 565 | */ |
| 566 | if (iter_mod < iter->module) |
| 567 | continue; |
| 568 | else if (iter_mod > iter->module) |
| 569 | iter->tracepoint = NULL; |
| 570 | found = tracepoint_get_iter_range(&iter->tracepoint, |
| 571 | iter_mod->tracepoints_ptrs, |
| 572 | iter_mod->tracepoints_ptrs |
| 573 | + iter_mod->num_tracepoints); |
| 574 | if (found) { |
| 575 | iter->module = iter_mod; |
| 576 | break; |
| 577 | } |
| 578 | } |
| 579 | mutex_unlock(&tracepoints_mutex); |
| 580 | end: |
| 581 | if (!found) |
| 582 | tracepoint_iter_reset(iter); |
| 583 | } |
| 584 | #else /* CONFIG_MODULES */ |
| 585 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
| 586 | { |
| 587 | int found = 0; |
| 588 | |
| 589 | /* Core kernel tracepoints */ |
| 590 | found = tracepoint_get_iter_range(&iter->tracepoint, |
| 591 | __start___tracepoints_ptrs, |
| 592 | __stop___tracepoints_ptrs); |
| 593 | if (!found) |
| 594 | tracepoint_iter_reset(iter); |
| 595 | } |
| 596 | #endif /* CONFIG_MODULES */ |
| 597 | |
| 598 | void tracepoint_iter_start(struct tracepoint_iter *iter) |
| 599 | { |
| 600 | tracepoint_get_iter(iter); |
| 601 | } |
| 602 | EXPORT_SYMBOL_GPL(tracepoint_iter_start); |
| 603 | |
| 604 | void tracepoint_iter_next(struct tracepoint_iter *iter) |
| 605 | { |
| 606 | iter->tracepoint++; |
| 607 | /* |
| 608 | * iter->tracepoint may be invalid because we blindly incremented it. |
| 609 | * Make sure it is valid by marshalling on the tracepoints, getting the |
| 610 | * tracepoints from following modules if necessary. |
| 611 | */ |
| 612 | tracepoint_get_iter(iter); |
| 613 | } |
| 614 | EXPORT_SYMBOL_GPL(tracepoint_iter_next); |
| 615 | |
| 616 | void tracepoint_iter_stop(struct tracepoint_iter *iter) |
| 617 | { |
| 618 | } |
| 619 | EXPORT_SYMBOL_GPL(tracepoint_iter_stop); |
| 620 | |
| 621 | void tracepoint_iter_reset(struct tracepoint_iter *iter) |
| 622 | { |
| 623 | #ifdef CONFIG_MODULES |
| 624 | iter->module = NULL; |
| 625 | #endif /* CONFIG_MODULES */ |
| 626 | iter->tracepoint = NULL; |
| 627 | } |
| 628 | EXPORT_SYMBOL_GPL(tracepoint_iter_reset); |
| 629 | |
| 630 | #ifdef CONFIG_MODULES |
| 631 | static int tracepoint_module_coming(struct module *mod) |
| 632 | { |
| 633 | struct tp_module *tp_mod, *iter; |
| 634 | int ret = 0; |
| 635 | |
| 636 | /* |
| 637 | * We skip modules that taint the kernel, especially those with different |
| 638 | * module headers (for forced load), to make sure we don't cause a crash. |
| 639 | * Staging and out-of-tree GPL modules are fine. |
| 640 | */ |
| 641 | if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP))) |
| 642 | return 0; |
| 643 | mutex_lock(&tracepoints_mutex); |
| 644 | tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); |
| 645 | if (!tp_mod) { |
| 646 | ret = -ENOMEM; |
| 647 | goto end; |
| 648 | } |
| 649 | tp_mod->num_tracepoints = mod->num_tracepoints; |
| 650 | tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs; |
| 651 | |
| 652 | /* |
| 653 | * tracepoint_module_list is kept sorted by struct module pointer |
| 654 | * address for iteration on tracepoints from a seq_file that can release |
| 655 | * the mutex between calls. |
| 656 | */ |
| 657 | list_for_each_entry_reverse(iter, &tracepoint_module_list, list) { |
| 658 | BUG_ON(iter == tp_mod); /* Should never be in the list twice */ |
| 659 | if (iter < tp_mod) { |
| 660 | /* We belong to the location right after iter. */ |
| 661 | list_add(&tp_mod->list, &iter->list); |
| 662 | goto module_added; |
| 663 | } |
| 664 | } |
| 665 | /* We belong to the beginning of the list */ |
| 666 | list_add(&tp_mod->list, &tracepoint_module_list); |
| 667 | module_added: |
| 668 | tracepoint_update_probe_range(mod->tracepoints_ptrs, |
| 669 | mod->tracepoints_ptrs + mod->num_tracepoints); |
| 670 | end: |
| 671 | mutex_unlock(&tracepoints_mutex); |
| 672 | return ret; |
| 673 | } |
| 674 | |
| 675 | static int tracepoint_module_going(struct module *mod) |
| 676 | { |
| 677 | struct tp_module *pos; |
| 678 | |
| 679 | mutex_lock(&tracepoints_mutex); |
| 680 | tracepoint_update_probe_range(mod->tracepoints_ptrs, |
| 681 | mod->tracepoints_ptrs + mod->num_tracepoints); |
| 682 | list_for_each_entry(pos, &tracepoint_module_list, list) { |
| 683 | if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) { |
| 684 | list_del(&pos->list); |
| 685 | kfree(pos); |
| 686 | break; |
| 687 | } |
| 688 | } |
| 689 | /* |
| 690 | * In the case of modules that were tainted at "coming", we'll simply |
| 691 | * walk through the list without finding it. We cannot use the "tainted" |
| 692 | * flag on "going", in case a module taints the kernel only after being |
| 693 | * loaded. |
| 694 | */ |
| 695 | mutex_unlock(&tracepoints_mutex); |
| 696 | return 0; |
| 697 | } |
| 698 | |
| 699 | int tracepoint_module_notify(struct notifier_block *self, |
| 700 | unsigned long val, void *data) |
| 701 | { |
| 702 | struct module *mod = data; |
| 703 | int ret = 0; |
| 704 | |
| 705 | switch (val) { |
| 706 | case MODULE_STATE_COMING: |
| 707 | ret = tracepoint_module_coming(mod); |
| 708 | break; |
| 709 | case MODULE_STATE_LIVE: |
| 710 | break; |
| 711 | case MODULE_STATE_GOING: |
| 712 | ret = tracepoint_module_going(mod); |
| 713 | break; |
| 714 | } |
| 715 | return ret; |
| 716 | } |
| 717 | |
| 718 | struct notifier_block tracepoint_module_nb = { |
| 719 | .notifier_call = tracepoint_module_notify, |
| 720 | .priority = 0, |
| 721 | }; |
| 722 | |
| 723 | static int init_tracepoints(void) |
| 724 | { |
| 725 | return register_module_notifier(&tracepoint_module_nb); |
| 726 | } |
| 727 | __initcall(init_tracepoints); |
| 728 | #endif /* CONFIG_MODULES */ |
| 729 | |
| 730 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
| 731 | |
| 732 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
| 733 | static int sys_tracepoint_refcount; |
| 734 | |
| 735 | void syscall_regfunc(void) |
| 736 | { |
| 737 | unsigned long flags; |
| 738 | struct task_struct *g, *t; |
| 739 | |
| 740 | if (!sys_tracepoint_refcount) { |
| 741 | read_lock_irqsave(&tasklist_lock, flags); |
| 742 | do_each_thread(g, t) { |
| 743 | /* Skip kernel threads. */ |
| 744 | if (t->mm) |
| 745 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
| 746 | } while_each_thread(g, t); |
| 747 | read_unlock_irqrestore(&tasklist_lock, flags); |
| 748 | } |
| 749 | sys_tracepoint_refcount++; |
| 750 | } |
| 751 | |
| 752 | void syscall_unregfunc(void) |
| 753 | { |
| 754 | unsigned long flags; |
| 755 | struct task_struct *g, *t; |
| 756 | |
| 757 | sys_tracepoint_refcount--; |
| 758 | if (!sys_tracepoint_refcount) { |
| 759 | read_lock_irqsave(&tasklist_lock, flags); |
| 760 | do_each_thread(g, t) { |
| 761 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
| 762 | } while_each_thread(g, t); |
| 763 | read_unlock_irqrestore(&tasklist_lock, flags); |
| 764 | } |
| 765 | } |
| 766 | #endif |