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97e1c18e MD |
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> | |
a871bd33 | 27 | #include <linux/sched.h> |
c5905afb | 28 | #include <linux/static_key.h> |
97e1c18e | 29 | |
65498646 MD |
30 | extern struct tracepoint * const __start___tracepoints_ptrs[]; |
31 | extern struct tracepoint * const __stop___tracepoints_ptrs[]; | |
97e1c18e MD |
32 | |
33 | /* Set to 1 to enable tracepoint debug output */ | |
34 | static const int tracepoint_debug; | |
35 | ||
36 | /* | |
b75ef8b4 MD |
37 | * Tracepoints mutex protects the builtin and module tracepoints and the hash |
38 | * table, as well as the local module list. | |
97e1c18e MD |
39 | */ |
40 | static DEFINE_MUTEX(tracepoints_mutex); | |
41 | ||
b75ef8b4 MD |
42 | #ifdef CONFIG_MODULES |
43 | /* Local list of struct module */ | |
44 | static LIST_HEAD(tracepoint_module_list); | |
45 | #endif /* CONFIG_MODULES */ | |
46 | ||
97e1c18e MD |
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) | |
19dba33c | 53 | static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; |
97e1c18e MD |
54 | |
55 | /* | |
56 | * Note about RCU : | |
fd589a8f | 57 | * It is used to delay the free of multiple probes array until a quiescent |
97e1c18e MD |
58 | * state is reached. |
59 | * Tracepoint entries modifications are protected by the tracepoints_mutex. | |
60 | */ | |
61 | struct tracepoint_entry { | |
62 | struct hlist_node hlist; | |
38516ab5 | 63 | struct tracepoint_func *funcs; |
97e1c18e | 64 | int refcount; /* Number of times armed. 0 if disarmed. */ |
97e1c18e MD |
65 | char name[0]; |
66 | }; | |
67 | ||
19dba33c | 68 | struct tp_probes { |
127cafbb LJ |
69 | union { |
70 | struct rcu_head rcu; | |
71 | struct list_head list; | |
72 | } u; | |
38516ab5 | 73 | struct tracepoint_func probes[0]; |
19dba33c | 74 | }; |
97e1c18e | 75 | |
19dba33c | 76 | static inline void *allocate_probes(int count) |
97e1c18e | 77 | { |
38516ab5 | 78 | struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) |
19dba33c LJ |
79 | + sizeof(struct tp_probes), GFP_KERNEL); |
80 | return p == NULL ? NULL : p->probes; | |
97e1c18e MD |
81 | } |
82 | ||
19dba33c | 83 | static void rcu_free_old_probes(struct rcu_head *head) |
97e1c18e | 84 | { |
127cafbb | 85 | kfree(container_of(head, struct tp_probes, u.rcu)); |
19dba33c LJ |
86 | } |
87 | ||
38516ab5 | 88 | static inline void release_probes(struct tracepoint_func *old) |
19dba33c LJ |
89 | { |
90 | if (old) { | |
91 | struct tp_probes *tp_probes = container_of(old, | |
92 | struct tp_probes, probes[0]); | |
127cafbb | 93 | call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes); |
19dba33c | 94 | } |
97e1c18e MD |
95 | } |
96 | ||
97 | static void debug_print_probes(struct tracepoint_entry *entry) | |
98 | { | |
99 | int i; | |
100 | ||
19dba33c | 101 | if (!tracepoint_debug || !entry->funcs) |
97e1c18e MD |
102 | return; |
103 | ||
38516ab5 SR |
104 | for (i = 0; entry->funcs[i].func; i++) |
105 | printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func); | |
97e1c18e MD |
106 | } |
107 | ||
38516ab5 SR |
108 | static struct tracepoint_func * |
109 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, | |
110 | void *probe, void *data) | |
97e1c18e MD |
111 | { |
112 | int nr_probes = 0; | |
38516ab5 | 113 | struct tracepoint_func *old, *new; |
97e1c18e | 114 | |
4c69e6ea S |
115 | if (WARN_ON(!probe)) |
116 | return ERR_PTR(-EINVAL); | |
97e1c18e MD |
117 | |
118 | debug_print_probes(entry); | |
119 | old = entry->funcs; | |
120 | if (old) { | |
121 | /* (N -> N+1), (N != 0, 1) probes */ | |
38516ab5 SR |
122 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
123 | if (old[nr_probes].func == probe && | |
124 | old[nr_probes].data == data) | |
97e1c18e MD |
125 | return ERR_PTR(-EEXIST); |
126 | } | |
127 | /* + 2 : one for new probe, one for NULL func */ | |
19dba33c | 128 | new = allocate_probes(nr_probes + 2); |
97e1c18e MD |
129 | if (new == NULL) |
130 | return ERR_PTR(-ENOMEM); | |
131 | if (old) | |
38516ab5 SR |
132 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); |
133 | new[nr_probes].func = probe; | |
134 | new[nr_probes].data = data; | |
135 | new[nr_probes + 1].func = NULL; | |
97e1c18e MD |
136 | entry->refcount = nr_probes + 1; |
137 | entry->funcs = new; | |
138 | debug_print_probes(entry); | |
139 | return old; | |
140 | } | |
141 | ||
142 | static void * | |
38516ab5 SR |
143 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, |
144 | void *probe, void *data) | |
97e1c18e MD |
145 | { |
146 | int nr_probes = 0, nr_del = 0, i; | |
38516ab5 | 147 | struct tracepoint_func *old, *new; |
97e1c18e MD |
148 | |
149 | old = entry->funcs; | |
150 | ||
f66af459 | 151 | if (!old) |
19dba33c | 152 | return ERR_PTR(-ENOENT); |
f66af459 | 153 | |
97e1c18e MD |
154 | debug_print_probes(entry); |
155 | /* (N -> M), (N > 1, M >= 0) probes */ | |
4c69e6ea S |
156 | if (probe) { |
157 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { | |
158 | if (old[nr_probes].func == probe && | |
159 | old[nr_probes].data == data) | |
160 | nr_del++; | |
161 | } | |
97e1c18e MD |
162 | } |
163 | ||
4c69e6ea S |
164 | /* |
165 | * If probe is NULL, then nr_probes = nr_del = 0, and then the | |
166 | * entire entry will be removed. | |
167 | */ | |
97e1c18e MD |
168 | if (nr_probes - nr_del == 0) { |
169 | /* N -> 0, (N > 1) */ | |
170 | entry->funcs = NULL; | |
171 | entry->refcount = 0; | |
172 | debug_print_probes(entry); | |
173 | return old; | |
174 | } else { | |
175 | int j = 0; | |
176 | /* N -> M, (N > 1, M > 0) */ | |
177 | /* + 1 for NULL */ | |
19dba33c | 178 | new = allocate_probes(nr_probes - nr_del + 1); |
97e1c18e MD |
179 | if (new == NULL) |
180 | return ERR_PTR(-ENOMEM); | |
38516ab5 | 181 | for (i = 0; old[i].func; i++) |
4c69e6ea | 182 | if (old[i].func != probe || old[i].data != data) |
97e1c18e | 183 | new[j++] = old[i]; |
38516ab5 | 184 | new[nr_probes - nr_del].func = NULL; |
97e1c18e MD |
185 | entry->refcount = nr_probes - nr_del; |
186 | entry->funcs = new; | |
187 | } | |
188 | debug_print_probes(entry); | |
189 | return old; | |
190 | } | |
191 | ||
192 | /* | |
193 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. | |
194 | * Must be called with tracepoints_mutex held. | |
195 | * Returns NULL if not present. | |
196 | */ | |
197 | static struct tracepoint_entry *get_tracepoint(const char *name) | |
198 | { | |
199 | struct hlist_head *head; | |
200 | struct hlist_node *node; | |
201 | struct tracepoint_entry *e; | |
202 | u32 hash = jhash(name, strlen(name), 0); | |
203 | ||
9795302a | 204 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
97e1c18e MD |
205 | hlist_for_each_entry(e, node, head, hlist) { |
206 | if (!strcmp(name, e->name)) | |
207 | return e; | |
208 | } | |
209 | return NULL; | |
210 | } | |
211 | ||
212 | /* | |
213 | * Add the tracepoint to the tracepoint hash table. Must be called with | |
214 | * tracepoints_mutex held. | |
215 | */ | |
216 | static struct tracepoint_entry *add_tracepoint(const char *name) | |
217 | { | |
218 | struct hlist_head *head; | |
219 | struct hlist_node *node; | |
220 | struct tracepoint_entry *e; | |
221 | size_t name_len = strlen(name) + 1; | |
222 | u32 hash = jhash(name, name_len-1, 0); | |
223 | ||
9795302a | 224 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
97e1c18e MD |
225 | hlist_for_each_entry(e, node, head, hlist) { |
226 | if (!strcmp(name, e->name)) { | |
227 | printk(KERN_NOTICE | |
228 | "tracepoint %s busy\n", name); | |
229 | return ERR_PTR(-EEXIST); /* Already there */ | |
230 | } | |
231 | } | |
232 | /* | |
233 | * Using kmalloc here to allocate a variable length element. Could | |
234 | * cause some memory fragmentation if overused. | |
235 | */ | |
236 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); | |
237 | if (!e) | |
238 | return ERR_PTR(-ENOMEM); | |
239 | memcpy(&e->name[0], name, name_len); | |
240 | e->funcs = NULL; | |
241 | e->refcount = 0; | |
97e1c18e MD |
242 | hlist_add_head(&e->hlist, head); |
243 | return e; | |
244 | } | |
245 | ||
246 | /* | |
247 | * Remove the tracepoint from the tracepoint hash table. Must be called with | |
248 | * mutex_lock held. | |
249 | */ | |
19dba33c | 250 | static inline void remove_tracepoint(struct tracepoint_entry *e) |
97e1c18e | 251 | { |
97e1c18e | 252 | hlist_del(&e->hlist); |
97e1c18e | 253 | kfree(e); |
97e1c18e MD |
254 | } |
255 | ||
256 | /* | |
257 | * Sets the probe callback corresponding to one tracepoint. | |
258 | */ | |
259 | static void set_tracepoint(struct tracepoint_entry **entry, | |
260 | struct tracepoint *elem, int active) | |
261 | { | |
262 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); | |
263 | ||
c5905afb | 264 | if (elem->regfunc && !static_key_enabled(&elem->key) && active) |
97419875 | 265 | elem->regfunc(); |
c5905afb | 266 | else if (elem->unregfunc && static_key_enabled(&elem->key) && !active) |
97419875 JS |
267 | elem->unregfunc(); |
268 | ||
97e1c18e MD |
269 | /* |
270 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new | |
271 | * probe callbacks array is consistent before setting a pointer to it. | |
272 | * This array is referenced by __DO_TRACE from | |
273 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() | |
274 | * is used. | |
275 | */ | |
276 | rcu_assign_pointer(elem->funcs, (*entry)->funcs); | |
c5905afb IM |
277 | if (active && !static_key_enabled(&elem->key)) |
278 | static_key_slow_inc(&elem->key); | |
279 | else if (!active && static_key_enabled(&elem->key)) | |
280 | static_key_slow_dec(&elem->key); | |
97e1c18e MD |
281 | } |
282 | ||
283 | /* | |
284 | * Disable a tracepoint and its probe callback. | |
285 | * Note: only waiting an RCU period after setting elem->call to the empty | |
286 | * function insures that the original callback is not used anymore. This insured | |
287 | * by preempt_disable around the call site. | |
288 | */ | |
289 | static void disable_tracepoint(struct tracepoint *elem) | |
290 | { | |
c5905afb | 291 | if (elem->unregfunc && static_key_enabled(&elem->key)) |
97419875 JS |
292 | elem->unregfunc(); |
293 | ||
c5905afb IM |
294 | if (static_key_enabled(&elem->key)) |
295 | static_key_slow_dec(&elem->key); | |
de0baf9a | 296 | rcu_assign_pointer(elem->funcs, NULL); |
97e1c18e MD |
297 | } |
298 | ||
299 | /** | |
300 | * tracepoint_update_probe_range - Update a probe range | |
301 | * @begin: beginning of the range | |
302 | * @end: end of the range | |
303 | * | |
304 | * Updates the probe callback corresponding to a range of tracepoints. | |
b75ef8b4 | 305 | * Called with tracepoints_mutex held. |
97e1c18e | 306 | */ |
b75ef8b4 MD |
307 | static void tracepoint_update_probe_range(struct tracepoint * const *begin, |
308 | struct tracepoint * const *end) | |
97e1c18e | 309 | { |
65498646 | 310 | struct tracepoint * const *iter; |
97e1c18e MD |
311 | struct tracepoint_entry *mark_entry; |
312 | ||
ec625cb2 | 313 | if (!begin) |
09933a10 | 314 | return; |
09933a10 | 315 | |
97e1c18e | 316 | for (iter = begin; iter < end; iter++) { |
65498646 | 317 | mark_entry = get_tracepoint((*iter)->name); |
97e1c18e | 318 | if (mark_entry) { |
65498646 | 319 | set_tracepoint(&mark_entry, *iter, |
97e1c18e MD |
320 | !!mark_entry->refcount); |
321 | } else { | |
65498646 | 322 | disable_tracepoint(*iter); |
97e1c18e MD |
323 | } |
324 | } | |
97e1c18e MD |
325 | } |
326 | ||
b75ef8b4 MD |
327 | #ifdef CONFIG_MODULES |
328 | void module_update_tracepoints(void) | |
329 | { | |
330 | struct tp_module *tp_mod; | |
331 | ||
332 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) | |
333 | tracepoint_update_probe_range(tp_mod->tracepoints_ptrs, | |
334 | tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints); | |
335 | } | |
336 | #else /* CONFIG_MODULES */ | |
337 | void module_update_tracepoints(void) | |
338 | { | |
339 | } | |
340 | #endif /* CONFIG_MODULES */ | |
341 | ||
342 | ||
97e1c18e MD |
343 | /* |
344 | * Update probes, removing the faulty probes. | |
b75ef8b4 | 345 | * Called with tracepoints_mutex held. |
97e1c18e MD |
346 | */ |
347 | static void tracepoint_update_probes(void) | |
348 | { | |
349 | /* Core kernel tracepoints */ | |
65498646 MD |
350 | tracepoint_update_probe_range(__start___tracepoints_ptrs, |
351 | __stop___tracepoints_ptrs); | |
97e1c18e MD |
352 | /* tracepoints in modules. */ |
353 | module_update_tracepoints(); | |
354 | } | |
355 | ||
38516ab5 SR |
356 | static struct tracepoint_func * |
357 | tracepoint_add_probe(const char *name, void *probe, void *data) | |
127cafbb LJ |
358 | { |
359 | struct tracepoint_entry *entry; | |
38516ab5 | 360 | struct tracepoint_func *old; |
127cafbb LJ |
361 | |
362 | entry = get_tracepoint(name); | |
363 | if (!entry) { | |
364 | entry = add_tracepoint(name); | |
365 | if (IS_ERR(entry)) | |
38516ab5 | 366 | return (struct tracepoint_func *)entry; |
127cafbb | 367 | } |
38516ab5 | 368 | old = tracepoint_entry_add_probe(entry, probe, data); |
127cafbb LJ |
369 | if (IS_ERR(old) && !entry->refcount) |
370 | remove_tracepoint(entry); | |
371 | return old; | |
372 | } | |
373 | ||
97e1c18e MD |
374 | /** |
375 | * tracepoint_probe_register - Connect a probe to a tracepoint | |
376 | * @name: tracepoint name | |
377 | * @probe: probe handler | |
378 | * | |
379 | * Returns 0 if ok, error value on error. | |
380 | * The probe address must at least be aligned on the architecture pointer size. | |
381 | */ | |
38516ab5 | 382 | int tracepoint_probe_register(const char *name, void *probe, void *data) |
97e1c18e | 383 | { |
38516ab5 | 384 | struct tracepoint_func *old; |
97e1c18e MD |
385 | |
386 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 387 | old = tracepoint_add_probe(name, probe, data); |
b75ef8b4 MD |
388 | if (IS_ERR(old)) { |
389 | mutex_unlock(&tracepoints_mutex); | |
127cafbb | 390 | return PTR_ERR(old); |
b75ef8b4 | 391 | } |
97e1c18e | 392 | tracepoint_update_probes(); /* may update entry */ |
b75ef8b4 | 393 | mutex_unlock(&tracepoints_mutex); |
19dba33c LJ |
394 | release_probes(old); |
395 | return 0; | |
97e1c18e MD |
396 | } |
397 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); | |
398 | ||
38516ab5 SR |
399 | static struct tracepoint_func * |
400 | tracepoint_remove_probe(const char *name, void *probe, void *data) | |
127cafbb LJ |
401 | { |
402 | struct tracepoint_entry *entry; | |
38516ab5 | 403 | struct tracepoint_func *old; |
127cafbb LJ |
404 | |
405 | entry = get_tracepoint(name); | |
406 | if (!entry) | |
407 | return ERR_PTR(-ENOENT); | |
38516ab5 | 408 | old = tracepoint_entry_remove_probe(entry, probe, data); |
127cafbb LJ |
409 | if (IS_ERR(old)) |
410 | return old; | |
411 | if (!entry->refcount) | |
412 | remove_tracepoint(entry); | |
413 | return old; | |
414 | } | |
415 | ||
97e1c18e MD |
416 | /** |
417 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint | |
418 | * @name: tracepoint name | |
419 | * @probe: probe function pointer | |
420 | * | |
421 | * We do not need to call a synchronize_sched to make sure the probes have | |
422 | * finished running before doing a module unload, because the module unload | |
423 | * itself uses stop_machine(), which insures that every preempt disabled section | |
424 | * have finished. | |
425 | */ | |
38516ab5 | 426 | int tracepoint_probe_unregister(const char *name, void *probe, void *data) |
97e1c18e | 427 | { |
38516ab5 | 428 | struct tracepoint_func *old; |
97e1c18e MD |
429 | |
430 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 431 | old = tracepoint_remove_probe(name, probe, data); |
b75ef8b4 MD |
432 | if (IS_ERR(old)) { |
433 | mutex_unlock(&tracepoints_mutex); | |
127cafbb | 434 | return PTR_ERR(old); |
b75ef8b4 | 435 | } |
97e1c18e | 436 | tracepoint_update_probes(); /* may update entry */ |
b75ef8b4 | 437 | mutex_unlock(&tracepoints_mutex); |
19dba33c LJ |
438 | release_probes(old); |
439 | return 0; | |
97e1c18e MD |
440 | } |
441 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); | |
442 | ||
127cafbb LJ |
443 | static LIST_HEAD(old_probes); |
444 | static int need_update; | |
445 | ||
446 | static void tracepoint_add_old_probes(void *old) | |
447 | { | |
448 | need_update = 1; | |
449 | if (old) { | |
450 | struct tp_probes *tp_probes = container_of(old, | |
451 | struct tp_probes, probes[0]); | |
452 | list_add(&tp_probes->u.list, &old_probes); | |
453 | } | |
454 | } | |
455 | ||
456 | /** | |
457 | * tracepoint_probe_register_noupdate - register a probe but not connect | |
458 | * @name: tracepoint name | |
459 | * @probe: probe handler | |
460 | * | |
461 | * caller must call tracepoint_probe_update_all() | |
462 | */ | |
38516ab5 SR |
463 | int tracepoint_probe_register_noupdate(const char *name, void *probe, |
464 | void *data) | |
127cafbb | 465 | { |
38516ab5 | 466 | struct tracepoint_func *old; |
127cafbb LJ |
467 | |
468 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 469 | old = tracepoint_add_probe(name, probe, data); |
127cafbb LJ |
470 | if (IS_ERR(old)) { |
471 | mutex_unlock(&tracepoints_mutex); | |
472 | return PTR_ERR(old); | |
473 | } | |
474 | tracepoint_add_old_probes(old); | |
475 | mutex_unlock(&tracepoints_mutex); | |
476 | return 0; | |
477 | } | |
478 | EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); | |
479 | ||
480 | /** | |
481 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect | |
482 | * @name: tracepoint name | |
483 | * @probe: probe function pointer | |
484 | * | |
485 | * caller must call tracepoint_probe_update_all() | |
486 | */ | |
38516ab5 SR |
487 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe, |
488 | void *data) | |
127cafbb | 489 | { |
38516ab5 | 490 | struct tracepoint_func *old; |
127cafbb LJ |
491 | |
492 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 493 | old = tracepoint_remove_probe(name, probe, data); |
127cafbb LJ |
494 | if (IS_ERR(old)) { |
495 | mutex_unlock(&tracepoints_mutex); | |
496 | return PTR_ERR(old); | |
497 | } | |
498 | tracepoint_add_old_probes(old); | |
499 | mutex_unlock(&tracepoints_mutex); | |
500 | return 0; | |
501 | } | |
502 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); | |
503 | ||
504 | /** | |
505 | * tracepoint_probe_update_all - update tracepoints | |
506 | */ | |
507 | void tracepoint_probe_update_all(void) | |
508 | { | |
509 | LIST_HEAD(release_probes); | |
510 | struct tp_probes *pos, *next; | |
511 | ||
512 | mutex_lock(&tracepoints_mutex); | |
513 | if (!need_update) { | |
514 | mutex_unlock(&tracepoints_mutex); | |
515 | return; | |
516 | } | |
517 | if (!list_empty(&old_probes)) | |
518 | list_replace_init(&old_probes, &release_probes); | |
519 | need_update = 0; | |
127cafbb | 520 | tracepoint_update_probes(); |
b75ef8b4 | 521 | mutex_unlock(&tracepoints_mutex); |
127cafbb LJ |
522 | list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
523 | list_del(&pos->u.list); | |
524 | call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); | |
525 | } | |
526 | } | |
527 | EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); | |
528 | ||
97e1c18e MD |
529 | /** |
530 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. | |
531 | * @tracepoint: current tracepoints (in), next tracepoint (out) | |
532 | * @begin: beginning of the range | |
533 | * @end: end of the range | |
534 | * | |
535 | * Returns whether a next tracepoint has been found (1) or not (0). | |
536 | * Will return the first tracepoint in the range if the input tracepoint is | |
537 | * NULL. | |
538 | */ | |
b75ef8b4 | 539 | static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, |
65498646 | 540 | struct tracepoint * const *begin, struct tracepoint * const *end) |
97e1c18e MD |
541 | { |
542 | if (!*tracepoint && begin != end) { | |
543 | *tracepoint = begin; | |
544 | return 1; | |
545 | } | |
546 | if (*tracepoint >= begin && *tracepoint < end) | |
547 | return 1; | |
548 | return 0; | |
549 | } | |
97e1c18e | 550 | |
b75ef8b4 | 551 | #ifdef CONFIG_MODULES |
97e1c18e MD |
552 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
553 | { | |
554 | int found = 0; | |
b75ef8b4 | 555 | struct tp_module *iter_mod; |
97e1c18e MD |
556 | |
557 | /* Core kernel tracepoints */ | |
558 | if (!iter->module) { | |
559 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
65498646 MD |
560 | __start___tracepoints_ptrs, |
561 | __stop___tracepoints_ptrs); | |
97e1c18e MD |
562 | if (found) |
563 | goto end; | |
564 | } | |
b75ef8b4 MD |
565 | /* Tracepoints in modules */ |
566 | mutex_lock(&tracepoints_mutex); | |
567 | list_for_each_entry(iter_mod, &tracepoint_module_list, list) { | |
568 | /* | |
569 | * Sorted module list | |
570 | */ | |
571 | if (iter_mod < iter->module) | |
572 | continue; | |
573 | else if (iter_mod > iter->module) | |
574 | iter->tracepoint = NULL; | |
575 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
576 | iter_mod->tracepoints_ptrs, | |
577 | iter_mod->tracepoints_ptrs | |
578 | + iter_mod->num_tracepoints); | |
579 | if (found) { | |
580 | iter->module = iter_mod; | |
581 | break; | |
582 | } | |
583 | } | |
584 | mutex_unlock(&tracepoints_mutex); | |
97e1c18e MD |
585 | end: |
586 | if (!found) | |
587 | tracepoint_iter_reset(iter); | |
588 | } | |
b75ef8b4 MD |
589 | #else /* CONFIG_MODULES */ |
590 | static void tracepoint_get_iter(struct tracepoint_iter *iter) | |
591 | { | |
592 | int found = 0; | |
593 | ||
594 | /* Core kernel tracepoints */ | |
595 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
596 | __start___tracepoints_ptrs, | |
597 | __stop___tracepoints_ptrs); | |
598 | if (!found) | |
599 | tracepoint_iter_reset(iter); | |
600 | } | |
601 | #endif /* CONFIG_MODULES */ | |
97e1c18e MD |
602 | |
603 | void tracepoint_iter_start(struct tracepoint_iter *iter) | |
604 | { | |
605 | tracepoint_get_iter(iter); | |
606 | } | |
607 | EXPORT_SYMBOL_GPL(tracepoint_iter_start); | |
608 | ||
609 | void tracepoint_iter_next(struct tracepoint_iter *iter) | |
610 | { | |
611 | iter->tracepoint++; | |
612 | /* | |
613 | * iter->tracepoint may be invalid because we blindly incremented it. | |
614 | * Make sure it is valid by marshalling on the tracepoints, getting the | |
615 | * tracepoints from following modules if necessary. | |
616 | */ | |
617 | tracepoint_get_iter(iter); | |
618 | } | |
619 | EXPORT_SYMBOL_GPL(tracepoint_iter_next); | |
620 | ||
621 | void tracepoint_iter_stop(struct tracepoint_iter *iter) | |
622 | { | |
623 | } | |
624 | EXPORT_SYMBOL_GPL(tracepoint_iter_stop); | |
625 | ||
626 | void tracepoint_iter_reset(struct tracepoint_iter *iter) | |
627 | { | |
b75ef8b4 | 628 | #ifdef CONFIG_MODULES |
97e1c18e | 629 | iter->module = NULL; |
b75ef8b4 | 630 | #endif /* CONFIG_MODULES */ |
97e1c18e MD |
631 | iter->tracepoint = NULL; |
632 | } | |
633 | EXPORT_SYMBOL_GPL(tracepoint_iter_reset); | |
32f85742 | 634 | |
227a8375 | 635 | #ifdef CONFIG_MODULES |
b75ef8b4 MD |
636 | static int tracepoint_module_coming(struct module *mod) |
637 | { | |
638 | struct tp_module *tp_mod, *iter; | |
639 | int ret = 0; | |
640 | ||
641 | /* | |
c10076c4 SR |
642 | * We skip modules that taint the kernel, especially those with different |
643 | * module headers (for forced load), to make sure we don't cause a crash. | |
644 | * Staging and out-of-tree GPL modules are fine. | |
b75ef8b4 | 645 | */ |
c10076c4 | 646 | if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP))) |
b75ef8b4 MD |
647 | return 0; |
648 | mutex_lock(&tracepoints_mutex); | |
649 | tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); | |
650 | if (!tp_mod) { | |
651 | ret = -ENOMEM; | |
652 | goto end; | |
653 | } | |
654 | tp_mod->num_tracepoints = mod->num_tracepoints; | |
655 | tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs; | |
656 | ||
657 | /* | |
658 | * tracepoint_module_list is kept sorted by struct module pointer | |
659 | * address for iteration on tracepoints from a seq_file that can release | |
660 | * the mutex between calls. | |
661 | */ | |
662 | list_for_each_entry_reverse(iter, &tracepoint_module_list, list) { | |
663 | BUG_ON(iter == tp_mod); /* Should never be in the list twice */ | |
664 | if (iter < tp_mod) { | |
665 | /* We belong to the location right after iter. */ | |
666 | list_add(&tp_mod->list, &iter->list); | |
667 | goto module_added; | |
668 | } | |
669 | } | |
670 | /* We belong to the beginning of the list */ | |
671 | list_add(&tp_mod->list, &tracepoint_module_list); | |
672 | module_added: | |
673 | tracepoint_update_probe_range(mod->tracepoints_ptrs, | |
674 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
675 | end: | |
676 | mutex_unlock(&tracepoints_mutex); | |
677 | return ret; | |
678 | } | |
679 | ||
680 | static int tracepoint_module_going(struct module *mod) | |
681 | { | |
682 | struct tp_module *pos; | |
683 | ||
684 | mutex_lock(&tracepoints_mutex); | |
685 | tracepoint_update_probe_range(mod->tracepoints_ptrs, | |
686 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
687 | list_for_each_entry(pos, &tracepoint_module_list, list) { | |
688 | if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) { | |
689 | list_del(&pos->list); | |
690 | kfree(pos); | |
691 | break; | |
692 | } | |
693 | } | |
694 | /* | |
695 | * In the case of modules that were tainted at "coming", we'll simply | |
696 | * walk through the list without finding it. We cannot use the "tainted" | |
697 | * flag on "going", in case a module taints the kernel only after being | |
698 | * loaded. | |
699 | */ | |
700 | mutex_unlock(&tracepoints_mutex); | |
701 | return 0; | |
702 | } | |
227a8375 | 703 | |
32f85742 MD |
704 | int tracepoint_module_notify(struct notifier_block *self, |
705 | unsigned long val, void *data) | |
706 | { | |
707 | struct module *mod = data; | |
b75ef8b4 | 708 | int ret = 0; |
32f85742 MD |
709 | |
710 | switch (val) { | |
711 | case MODULE_STATE_COMING: | |
b75ef8b4 MD |
712 | ret = tracepoint_module_coming(mod); |
713 | break; | |
714 | case MODULE_STATE_LIVE: | |
715 | break; | |
32f85742 | 716 | case MODULE_STATE_GOING: |
b75ef8b4 | 717 | ret = tracepoint_module_going(mod); |
32f85742 MD |
718 | break; |
719 | } | |
b75ef8b4 | 720 | return ret; |
32f85742 MD |
721 | } |
722 | ||
723 | struct notifier_block tracepoint_module_nb = { | |
724 | .notifier_call = tracepoint_module_notify, | |
725 | .priority = 0, | |
726 | }; | |
727 | ||
728 | static int init_tracepoints(void) | |
729 | { | |
730 | return register_module_notifier(&tracepoint_module_nb); | |
731 | } | |
732 | __initcall(init_tracepoints); | |
227a8375 | 733 | #endif /* CONFIG_MODULES */ |
a871bd33 | 734 | |
3d27d8cb | 735 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
60d970c2 | 736 | |
97419875 | 737 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
a871bd33 JB |
738 | static int sys_tracepoint_refcount; |
739 | ||
740 | void syscall_regfunc(void) | |
741 | { | |
742 | unsigned long flags; | |
743 | struct task_struct *g, *t; | |
744 | ||
a871bd33 JB |
745 | if (!sys_tracepoint_refcount) { |
746 | read_lock_irqsave(&tasklist_lock, flags); | |
747 | do_each_thread(g, t) { | |
cc3b13c1 HB |
748 | /* Skip kernel threads. */ |
749 | if (t->mm) | |
750 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); | |
a871bd33 JB |
751 | } while_each_thread(g, t); |
752 | read_unlock_irqrestore(&tasklist_lock, flags); | |
753 | } | |
754 | sys_tracepoint_refcount++; | |
a871bd33 JB |
755 | } |
756 | ||
757 | void syscall_unregfunc(void) | |
758 | { | |
759 | unsigned long flags; | |
760 | struct task_struct *g, *t; | |
761 | ||
a871bd33 JB |
762 | sys_tracepoint_refcount--; |
763 | if (!sys_tracepoint_refcount) { | |
764 | read_lock_irqsave(&tasklist_lock, flags); | |
765 | do_each_thread(g, t) { | |
66700001 | 766 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
a871bd33 JB |
767 | } while_each_thread(g, t); |
768 | read_unlock_irqrestore(&tasklist_lock, flags); | |
769 | } | |
a871bd33 | 770 | } |
60d970c2 | 771 | #endif |