Commit | Line | Data |
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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. */ |
b196e2b9 | 65 | int enabled; /* Tracepoint enabled */ |
97e1c18e MD |
66 | char name[0]; |
67 | }; | |
68 | ||
19dba33c | 69 | struct tp_probes { |
127cafbb LJ |
70 | union { |
71 | struct rcu_head rcu; | |
72 | struct list_head list; | |
73 | } u; | |
38516ab5 | 74 | struct tracepoint_func probes[0]; |
19dba33c | 75 | }; |
97e1c18e | 76 | |
19dba33c | 77 | static inline void *allocate_probes(int count) |
97e1c18e | 78 | { |
38516ab5 | 79 | struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) |
19dba33c LJ |
80 | + sizeof(struct tp_probes), GFP_KERNEL); |
81 | return p == NULL ? NULL : p->probes; | |
97e1c18e MD |
82 | } |
83 | ||
19dba33c | 84 | static void rcu_free_old_probes(struct rcu_head *head) |
97e1c18e | 85 | { |
127cafbb | 86 | kfree(container_of(head, struct tp_probes, u.rcu)); |
19dba33c LJ |
87 | } |
88 | ||
38516ab5 | 89 | static inline void release_probes(struct tracepoint_func *old) |
19dba33c LJ |
90 | { |
91 | if (old) { | |
92 | struct tp_probes *tp_probes = container_of(old, | |
93 | struct tp_probes, probes[0]); | |
127cafbb | 94 | call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes); |
19dba33c | 95 | } |
97e1c18e MD |
96 | } |
97 | ||
98 | static void debug_print_probes(struct tracepoint_entry *entry) | |
99 | { | |
100 | int i; | |
101 | ||
19dba33c | 102 | if (!tracepoint_debug || !entry->funcs) |
97e1c18e MD |
103 | return; |
104 | ||
38516ab5 SR |
105 | for (i = 0; entry->funcs[i].func; i++) |
106 | printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func); | |
97e1c18e MD |
107 | } |
108 | ||
38516ab5 SR |
109 | static struct tracepoint_func * |
110 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, | |
111 | void *probe, void *data) | |
97e1c18e MD |
112 | { |
113 | int nr_probes = 0; | |
38516ab5 | 114 | struct tracepoint_func *old, *new; |
97e1c18e | 115 | |
4c69e6ea S |
116 | if (WARN_ON(!probe)) |
117 | return ERR_PTR(-EINVAL); | |
97e1c18e MD |
118 | |
119 | debug_print_probes(entry); | |
120 | old = entry->funcs; | |
121 | if (old) { | |
122 | /* (N -> N+1), (N != 0, 1) probes */ | |
38516ab5 SR |
123 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
124 | if (old[nr_probes].func == probe && | |
125 | old[nr_probes].data == data) | |
97e1c18e MD |
126 | return ERR_PTR(-EEXIST); |
127 | } | |
128 | /* + 2 : one for new probe, one for NULL func */ | |
19dba33c | 129 | new = allocate_probes(nr_probes + 2); |
97e1c18e MD |
130 | if (new == NULL) |
131 | return ERR_PTR(-ENOMEM); | |
132 | if (old) | |
38516ab5 SR |
133 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); |
134 | new[nr_probes].func = probe; | |
135 | new[nr_probes].data = data; | |
136 | new[nr_probes + 1].func = NULL; | |
97e1c18e MD |
137 | entry->refcount = nr_probes + 1; |
138 | entry->funcs = new; | |
139 | debug_print_probes(entry); | |
140 | return old; | |
141 | } | |
142 | ||
143 | static void * | |
38516ab5 SR |
144 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, |
145 | void *probe, void *data) | |
97e1c18e MD |
146 | { |
147 | int nr_probes = 0, nr_del = 0, i; | |
38516ab5 | 148 | struct tracepoint_func *old, *new; |
97e1c18e MD |
149 | |
150 | old = entry->funcs; | |
151 | ||
f66af459 | 152 | if (!old) |
19dba33c | 153 | return ERR_PTR(-ENOENT); |
f66af459 | 154 | |
97e1c18e MD |
155 | debug_print_probes(entry); |
156 | /* (N -> M), (N > 1, M >= 0) probes */ | |
4c69e6ea S |
157 | if (probe) { |
158 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { | |
159 | if (old[nr_probes].func == probe && | |
160 | old[nr_probes].data == data) | |
161 | nr_del++; | |
162 | } | |
97e1c18e MD |
163 | } |
164 | ||
4c69e6ea S |
165 | /* |
166 | * If probe is NULL, then nr_probes = nr_del = 0, and then the | |
167 | * entire entry will be removed. | |
168 | */ | |
97e1c18e MD |
169 | if (nr_probes - nr_del == 0) { |
170 | /* N -> 0, (N > 1) */ | |
171 | entry->funcs = NULL; | |
172 | entry->refcount = 0; | |
173 | debug_print_probes(entry); | |
174 | return old; | |
175 | } else { | |
176 | int j = 0; | |
177 | /* N -> M, (N > 1, M > 0) */ | |
178 | /* + 1 for NULL */ | |
19dba33c | 179 | new = allocate_probes(nr_probes - nr_del + 1); |
97e1c18e MD |
180 | if (new == NULL) |
181 | return ERR_PTR(-ENOMEM); | |
38516ab5 | 182 | for (i = 0; old[i].func; i++) |
4c69e6ea | 183 | if (old[i].func != probe || old[i].data != data) |
97e1c18e | 184 | new[j++] = old[i]; |
38516ab5 | 185 | new[nr_probes - nr_del].func = NULL; |
97e1c18e MD |
186 | entry->refcount = nr_probes - nr_del; |
187 | entry->funcs = new; | |
188 | } | |
189 | debug_print_probes(entry); | |
190 | return old; | |
191 | } | |
192 | ||
193 | /* | |
194 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. | |
195 | * Must be called with tracepoints_mutex held. | |
196 | * Returns NULL if not present. | |
197 | */ | |
198 | static struct tracepoint_entry *get_tracepoint(const char *name) | |
199 | { | |
200 | struct hlist_head *head; | |
97e1c18e MD |
201 | struct tracepoint_entry *e; |
202 | u32 hash = jhash(name, strlen(name), 0); | |
203 | ||
9795302a | 204 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
b67bfe0d | 205 | hlist_for_each_entry(e, head, hlist) { |
97e1c18e MD |
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; | |
97e1c18e MD |
219 | struct tracepoint_entry *e; |
220 | size_t name_len = strlen(name) + 1; | |
221 | u32 hash = jhash(name, name_len-1, 0); | |
222 | ||
9795302a | 223 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
b67bfe0d | 224 | hlist_for_each_entry(e, head, hlist) { |
97e1c18e MD |
225 | if (!strcmp(name, e->name)) { |
226 | printk(KERN_NOTICE | |
227 | "tracepoint %s busy\n", name); | |
228 | return ERR_PTR(-EEXIST); /* Already there */ | |
229 | } | |
230 | } | |
231 | /* | |
232 | * Using kmalloc here to allocate a variable length element. Could | |
233 | * cause some memory fragmentation if overused. | |
234 | */ | |
235 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); | |
236 | if (!e) | |
237 | return ERR_PTR(-ENOMEM); | |
238 | memcpy(&e->name[0], name, name_len); | |
239 | e->funcs = NULL; | |
240 | e->refcount = 0; | |
b196e2b9 | 241 | e->enabled = 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 | 320 | !!mark_entry->refcount); |
b196e2b9 | 321 | mark_entry->enabled = !!mark_entry->refcount; |
97e1c18e | 322 | } else { |
65498646 | 323 | disable_tracepoint(*iter); |
97e1c18e MD |
324 | } |
325 | } | |
97e1c18e MD |
326 | } |
327 | ||
b75ef8b4 MD |
328 | #ifdef CONFIG_MODULES |
329 | void module_update_tracepoints(void) | |
330 | { | |
331 | struct tp_module *tp_mod; | |
332 | ||
333 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) | |
334 | tracepoint_update_probe_range(tp_mod->tracepoints_ptrs, | |
335 | tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints); | |
336 | } | |
337 | #else /* CONFIG_MODULES */ | |
338 | void module_update_tracepoints(void) | |
339 | { | |
340 | } | |
341 | #endif /* CONFIG_MODULES */ | |
342 | ||
343 | ||
97e1c18e MD |
344 | /* |
345 | * Update probes, removing the faulty probes. | |
b75ef8b4 | 346 | * Called with tracepoints_mutex held. |
97e1c18e MD |
347 | */ |
348 | static void tracepoint_update_probes(void) | |
349 | { | |
350 | /* Core kernel tracepoints */ | |
65498646 MD |
351 | tracepoint_update_probe_range(__start___tracepoints_ptrs, |
352 | __stop___tracepoints_ptrs); | |
97e1c18e MD |
353 | /* tracepoints in modules. */ |
354 | module_update_tracepoints(); | |
355 | } | |
356 | ||
38516ab5 SR |
357 | static struct tracepoint_func * |
358 | tracepoint_add_probe(const char *name, void *probe, void *data) | |
127cafbb LJ |
359 | { |
360 | struct tracepoint_entry *entry; | |
38516ab5 | 361 | struct tracepoint_func *old; |
127cafbb LJ |
362 | |
363 | entry = get_tracepoint(name); | |
364 | if (!entry) { | |
365 | entry = add_tracepoint(name); | |
366 | if (IS_ERR(entry)) | |
38516ab5 | 367 | return (struct tracepoint_func *)entry; |
127cafbb | 368 | } |
38516ab5 | 369 | old = tracepoint_entry_add_probe(entry, probe, data); |
127cafbb LJ |
370 | if (IS_ERR(old) && !entry->refcount) |
371 | remove_tracepoint(entry); | |
372 | return old; | |
373 | } | |
374 | ||
97e1c18e MD |
375 | /** |
376 | * tracepoint_probe_register - Connect a probe to a tracepoint | |
377 | * @name: tracepoint name | |
378 | * @probe: probe handler | |
4c11628a | 379 | * @data: probe private data |
97e1c18e | 380 | * |
3bbc8db3 MD |
381 | * Returns: |
382 | * - 0 if the probe was successfully registered, and tracepoint | |
383 | * callsites are currently loaded for that probe, | |
384 | * - -ENODEV if the probe was successfully registered, but no tracepoint | |
385 | * callsite is currently loaded for that probe, | |
386 | * - other negative error value on error. | |
387 | * | |
388 | * When tracepoint_probe_register() returns either 0 or -ENODEV, | |
389 | * parameters @name, @probe, and @data may be used by the tracepoint | |
390 | * infrastructure until the probe is unregistered. | |
391 | * | |
97e1c18e MD |
392 | * The probe address must at least be aligned on the architecture pointer size. |
393 | */ | |
38516ab5 | 394 | int tracepoint_probe_register(const char *name, void *probe, void *data) |
97e1c18e | 395 | { |
38516ab5 | 396 | struct tracepoint_func *old; |
b196e2b9 SR |
397 | struct tracepoint_entry *entry; |
398 | int ret = 0; | |
97e1c18e MD |
399 | |
400 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 401 | old = tracepoint_add_probe(name, probe, data); |
b75ef8b4 MD |
402 | if (IS_ERR(old)) { |
403 | mutex_unlock(&tracepoints_mutex); | |
127cafbb | 404 | return PTR_ERR(old); |
b75ef8b4 | 405 | } |
97e1c18e | 406 | tracepoint_update_probes(); /* may update entry */ |
b196e2b9 SR |
407 | entry = get_tracepoint(name); |
408 | /* Make sure the entry was enabled */ | |
409 | if (!entry || !entry->enabled) | |
410 | ret = -ENODEV; | |
b75ef8b4 | 411 | mutex_unlock(&tracepoints_mutex); |
19dba33c | 412 | release_probes(old); |
b196e2b9 | 413 | return ret; |
97e1c18e MD |
414 | } |
415 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); | |
416 | ||
38516ab5 SR |
417 | static struct tracepoint_func * |
418 | tracepoint_remove_probe(const char *name, void *probe, void *data) | |
127cafbb LJ |
419 | { |
420 | struct tracepoint_entry *entry; | |
38516ab5 | 421 | struct tracepoint_func *old; |
127cafbb LJ |
422 | |
423 | entry = get_tracepoint(name); | |
424 | if (!entry) | |
425 | return ERR_PTR(-ENOENT); | |
38516ab5 | 426 | old = tracepoint_entry_remove_probe(entry, probe, data); |
127cafbb LJ |
427 | if (IS_ERR(old)) |
428 | return old; | |
429 | if (!entry->refcount) | |
430 | remove_tracepoint(entry); | |
431 | return old; | |
432 | } | |
433 | ||
97e1c18e MD |
434 | /** |
435 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint | |
436 | * @name: tracepoint name | |
437 | * @probe: probe function pointer | |
4c11628a | 438 | * @data: probe private data |
97e1c18e MD |
439 | * |
440 | * We do not need to call a synchronize_sched to make sure the probes have | |
441 | * finished running before doing a module unload, because the module unload | |
442 | * itself uses stop_machine(), which insures that every preempt disabled section | |
443 | * have finished. | |
444 | */ | |
38516ab5 | 445 | int tracepoint_probe_unregister(const char *name, void *probe, void *data) |
97e1c18e | 446 | { |
38516ab5 | 447 | struct tracepoint_func *old; |
97e1c18e MD |
448 | |
449 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 450 | old = tracepoint_remove_probe(name, probe, data); |
b75ef8b4 MD |
451 | if (IS_ERR(old)) { |
452 | mutex_unlock(&tracepoints_mutex); | |
127cafbb | 453 | return PTR_ERR(old); |
b75ef8b4 | 454 | } |
97e1c18e | 455 | tracepoint_update_probes(); /* may update entry */ |
b75ef8b4 | 456 | mutex_unlock(&tracepoints_mutex); |
19dba33c LJ |
457 | release_probes(old); |
458 | return 0; | |
97e1c18e MD |
459 | } |
460 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); | |
461 | ||
127cafbb LJ |
462 | static LIST_HEAD(old_probes); |
463 | static int need_update; | |
464 | ||
465 | static void tracepoint_add_old_probes(void *old) | |
466 | { | |
467 | need_update = 1; | |
468 | if (old) { | |
469 | struct tp_probes *tp_probes = container_of(old, | |
470 | struct tp_probes, probes[0]); | |
471 | list_add(&tp_probes->u.list, &old_probes); | |
472 | } | |
473 | } | |
474 | ||
475 | /** | |
476 | * tracepoint_probe_register_noupdate - register a probe but not connect | |
477 | * @name: tracepoint name | |
478 | * @probe: probe handler | |
4c11628a | 479 | * @data: probe private data |
127cafbb LJ |
480 | * |
481 | * caller must call tracepoint_probe_update_all() | |
482 | */ | |
38516ab5 SR |
483 | int tracepoint_probe_register_noupdate(const char *name, void *probe, |
484 | void *data) | |
127cafbb | 485 | { |
38516ab5 | 486 | struct tracepoint_func *old; |
127cafbb LJ |
487 | |
488 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 489 | old = tracepoint_add_probe(name, probe, data); |
127cafbb LJ |
490 | if (IS_ERR(old)) { |
491 | mutex_unlock(&tracepoints_mutex); | |
492 | return PTR_ERR(old); | |
493 | } | |
494 | tracepoint_add_old_probes(old); | |
495 | mutex_unlock(&tracepoints_mutex); | |
496 | return 0; | |
497 | } | |
498 | EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); | |
499 | ||
500 | /** | |
501 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect | |
502 | * @name: tracepoint name | |
503 | * @probe: probe function pointer | |
4c11628a | 504 | * @data: probe private data |
127cafbb LJ |
505 | * |
506 | * caller must call tracepoint_probe_update_all() | |
507 | */ | |
38516ab5 SR |
508 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe, |
509 | void *data) | |
127cafbb | 510 | { |
38516ab5 | 511 | struct tracepoint_func *old; |
127cafbb LJ |
512 | |
513 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 514 | old = tracepoint_remove_probe(name, probe, data); |
127cafbb LJ |
515 | if (IS_ERR(old)) { |
516 | mutex_unlock(&tracepoints_mutex); | |
517 | return PTR_ERR(old); | |
518 | } | |
519 | tracepoint_add_old_probes(old); | |
520 | mutex_unlock(&tracepoints_mutex); | |
521 | return 0; | |
522 | } | |
523 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); | |
524 | ||
525 | /** | |
526 | * tracepoint_probe_update_all - update tracepoints | |
527 | */ | |
528 | void tracepoint_probe_update_all(void) | |
529 | { | |
530 | LIST_HEAD(release_probes); | |
531 | struct tp_probes *pos, *next; | |
532 | ||
533 | mutex_lock(&tracepoints_mutex); | |
534 | if (!need_update) { | |
535 | mutex_unlock(&tracepoints_mutex); | |
536 | return; | |
537 | } | |
538 | if (!list_empty(&old_probes)) | |
539 | list_replace_init(&old_probes, &release_probes); | |
540 | need_update = 0; | |
127cafbb | 541 | tracepoint_update_probes(); |
b75ef8b4 | 542 | mutex_unlock(&tracepoints_mutex); |
127cafbb LJ |
543 | list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
544 | list_del(&pos->u.list); | |
545 | call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); | |
546 | } | |
547 | } | |
548 | EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); | |
549 | ||
97e1c18e MD |
550 | /** |
551 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. | |
552 | * @tracepoint: current tracepoints (in), next tracepoint (out) | |
553 | * @begin: beginning of the range | |
554 | * @end: end of the range | |
555 | * | |
556 | * Returns whether a next tracepoint has been found (1) or not (0). | |
557 | * Will return the first tracepoint in the range if the input tracepoint is | |
558 | * NULL. | |
559 | */ | |
b75ef8b4 | 560 | static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, |
65498646 | 561 | struct tracepoint * const *begin, struct tracepoint * const *end) |
97e1c18e MD |
562 | { |
563 | if (!*tracepoint && begin != end) { | |
564 | *tracepoint = begin; | |
565 | return 1; | |
566 | } | |
567 | if (*tracepoint >= begin && *tracepoint < end) | |
568 | return 1; | |
569 | return 0; | |
570 | } | |
97e1c18e | 571 | |
b75ef8b4 | 572 | #ifdef CONFIG_MODULES |
97e1c18e MD |
573 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
574 | { | |
575 | int found = 0; | |
b75ef8b4 | 576 | struct tp_module *iter_mod; |
97e1c18e MD |
577 | |
578 | /* Core kernel tracepoints */ | |
579 | if (!iter->module) { | |
580 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
65498646 MD |
581 | __start___tracepoints_ptrs, |
582 | __stop___tracepoints_ptrs); | |
97e1c18e MD |
583 | if (found) |
584 | goto end; | |
585 | } | |
b75ef8b4 MD |
586 | /* Tracepoints in modules */ |
587 | mutex_lock(&tracepoints_mutex); | |
588 | list_for_each_entry(iter_mod, &tracepoint_module_list, list) { | |
589 | /* | |
590 | * Sorted module list | |
591 | */ | |
592 | if (iter_mod < iter->module) | |
593 | continue; | |
594 | else if (iter_mod > iter->module) | |
595 | iter->tracepoint = NULL; | |
596 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
597 | iter_mod->tracepoints_ptrs, | |
598 | iter_mod->tracepoints_ptrs | |
599 | + iter_mod->num_tracepoints); | |
600 | if (found) { | |
601 | iter->module = iter_mod; | |
602 | break; | |
603 | } | |
604 | } | |
605 | mutex_unlock(&tracepoints_mutex); | |
97e1c18e MD |
606 | end: |
607 | if (!found) | |
608 | tracepoint_iter_reset(iter); | |
609 | } | |
b75ef8b4 MD |
610 | #else /* CONFIG_MODULES */ |
611 | static void tracepoint_get_iter(struct tracepoint_iter *iter) | |
612 | { | |
613 | int found = 0; | |
614 | ||
615 | /* Core kernel tracepoints */ | |
616 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
617 | __start___tracepoints_ptrs, | |
618 | __stop___tracepoints_ptrs); | |
619 | if (!found) | |
620 | tracepoint_iter_reset(iter); | |
621 | } | |
622 | #endif /* CONFIG_MODULES */ | |
97e1c18e MD |
623 | |
624 | void tracepoint_iter_start(struct tracepoint_iter *iter) | |
625 | { | |
626 | tracepoint_get_iter(iter); | |
627 | } | |
628 | EXPORT_SYMBOL_GPL(tracepoint_iter_start); | |
629 | ||
630 | void tracepoint_iter_next(struct tracepoint_iter *iter) | |
631 | { | |
632 | iter->tracepoint++; | |
633 | /* | |
634 | * iter->tracepoint may be invalid because we blindly incremented it. | |
635 | * Make sure it is valid by marshalling on the tracepoints, getting the | |
636 | * tracepoints from following modules if necessary. | |
637 | */ | |
638 | tracepoint_get_iter(iter); | |
639 | } | |
640 | EXPORT_SYMBOL_GPL(tracepoint_iter_next); | |
641 | ||
642 | void tracepoint_iter_stop(struct tracepoint_iter *iter) | |
643 | { | |
644 | } | |
645 | EXPORT_SYMBOL_GPL(tracepoint_iter_stop); | |
646 | ||
647 | void tracepoint_iter_reset(struct tracepoint_iter *iter) | |
648 | { | |
b75ef8b4 | 649 | #ifdef CONFIG_MODULES |
97e1c18e | 650 | iter->module = NULL; |
b75ef8b4 | 651 | #endif /* CONFIG_MODULES */ |
97e1c18e MD |
652 | iter->tracepoint = NULL; |
653 | } | |
654 | EXPORT_SYMBOL_GPL(tracepoint_iter_reset); | |
32f85742 | 655 | |
227a8375 | 656 | #ifdef CONFIG_MODULES |
b75ef8b4 MD |
657 | static int tracepoint_module_coming(struct module *mod) |
658 | { | |
659 | struct tp_module *tp_mod, *iter; | |
660 | int ret = 0; | |
661 | ||
7dec935a SRRH |
662 | if (!mod->num_tracepoints) |
663 | return 0; | |
664 | ||
b75ef8b4 | 665 | /* |
c10076c4 SR |
666 | * We skip modules that taint the kernel, especially those with different |
667 | * module headers (for forced load), to make sure we don't cause a crash. | |
668 | * Staging and out-of-tree GPL modules are fine. | |
b75ef8b4 | 669 | */ |
c10076c4 | 670 | if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP))) |
b75ef8b4 MD |
671 | return 0; |
672 | mutex_lock(&tracepoints_mutex); | |
673 | tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); | |
674 | if (!tp_mod) { | |
675 | ret = -ENOMEM; | |
676 | goto end; | |
677 | } | |
678 | tp_mod->num_tracepoints = mod->num_tracepoints; | |
679 | tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs; | |
680 | ||
681 | /* | |
682 | * tracepoint_module_list is kept sorted by struct module pointer | |
683 | * address for iteration on tracepoints from a seq_file that can release | |
684 | * the mutex between calls. | |
685 | */ | |
686 | list_for_each_entry_reverse(iter, &tracepoint_module_list, list) { | |
687 | BUG_ON(iter == tp_mod); /* Should never be in the list twice */ | |
688 | if (iter < tp_mod) { | |
689 | /* We belong to the location right after iter. */ | |
690 | list_add(&tp_mod->list, &iter->list); | |
691 | goto module_added; | |
692 | } | |
693 | } | |
694 | /* We belong to the beginning of the list */ | |
695 | list_add(&tp_mod->list, &tracepoint_module_list); | |
696 | module_added: | |
697 | tracepoint_update_probe_range(mod->tracepoints_ptrs, | |
698 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
699 | end: | |
700 | mutex_unlock(&tracepoints_mutex); | |
701 | return ret; | |
702 | } | |
703 | ||
704 | static int tracepoint_module_going(struct module *mod) | |
705 | { | |
706 | struct tp_module *pos; | |
707 | ||
7dec935a SRRH |
708 | if (!mod->num_tracepoints) |
709 | return 0; | |
710 | ||
b75ef8b4 MD |
711 | mutex_lock(&tracepoints_mutex); |
712 | tracepoint_update_probe_range(mod->tracepoints_ptrs, | |
713 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
714 | list_for_each_entry(pos, &tracepoint_module_list, list) { | |
715 | if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) { | |
716 | list_del(&pos->list); | |
717 | kfree(pos); | |
718 | break; | |
719 | } | |
720 | } | |
721 | /* | |
722 | * In the case of modules that were tainted at "coming", we'll simply | |
723 | * walk through the list without finding it. We cannot use the "tainted" | |
724 | * flag on "going", in case a module taints the kernel only after being | |
725 | * loaded. | |
726 | */ | |
727 | mutex_unlock(&tracepoints_mutex); | |
728 | return 0; | |
729 | } | |
227a8375 | 730 | |
32f85742 MD |
731 | int tracepoint_module_notify(struct notifier_block *self, |
732 | unsigned long val, void *data) | |
733 | { | |
734 | struct module *mod = data; | |
b75ef8b4 | 735 | int ret = 0; |
32f85742 MD |
736 | |
737 | switch (val) { | |
738 | case MODULE_STATE_COMING: | |
b75ef8b4 MD |
739 | ret = tracepoint_module_coming(mod); |
740 | break; | |
741 | case MODULE_STATE_LIVE: | |
742 | break; | |
32f85742 | 743 | case MODULE_STATE_GOING: |
b75ef8b4 | 744 | ret = tracepoint_module_going(mod); |
32f85742 MD |
745 | break; |
746 | } | |
b75ef8b4 | 747 | return ret; |
32f85742 MD |
748 | } |
749 | ||
750 | struct notifier_block tracepoint_module_nb = { | |
751 | .notifier_call = tracepoint_module_notify, | |
752 | .priority = 0, | |
753 | }; | |
754 | ||
755 | static int init_tracepoints(void) | |
756 | { | |
757 | return register_module_notifier(&tracepoint_module_nb); | |
758 | } | |
759 | __initcall(init_tracepoints); | |
227a8375 | 760 | #endif /* CONFIG_MODULES */ |
a871bd33 | 761 | |
3d27d8cb | 762 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
60d970c2 | 763 | |
97419875 | 764 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
a871bd33 JB |
765 | static int sys_tracepoint_refcount; |
766 | ||
767 | void syscall_regfunc(void) | |
768 | { | |
769 | unsigned long flags; | |
770 | struct task_struct *g, *t; | |
771 | ||
a871bd33 JB |
772 | if (!sys_tracepoint_refcount) { |
773 | read_lock_irqsave(&tasklist_lock, flags); | |
774 | do_each_thread(g, t) { | |
cc3b13c1 HB |
775 | /* Skip kernel threads. */ |
776 | if (t->mm) | |
777 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); | |
a871bd33 JB |
778 | } while_each_thread(g, t); |
779 | read_unlock_irqrestore(&tasklist_lock, flags); | |
780 | } | |
781 | sys_tracepoint_refcount++; | |
a871bd33 JB |
782 | } |
783 | ||
784 | void syscall_unregfunc(void) | |
785 | { | |
786 | unsigned long flags; | |
787 | struct task_struct *g, *t; | |
788 | ||
a871bd33 JB |
789 | sys_tracepoint_refcount--; |
790 | if (!sys_tracepoint_refcount) { | |
791 | read_lock_irqsave(&tasklist_lock, flags); | |
792 | do_each_thread(g, t) { | |
66700001 | 793 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
a871bd33 JB |
794 | } while_each_thread(g, t); |
795 | read_unlock_irqrestore(&tasklist_lock, flags); | |
796 | } | |
a871bd33 | 797 | } |
60d970c2 | 798 | #endif |