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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 tracepoint_entry *e; |
196 | u32 hash = jhash(name, strlen(name), 0); |
197 | |
198 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
199 | hlist_for_each_entry(e, head, hlist) { |
200 | if (!strcmp(name, e->name)) |
201 | return e; |
202 | } |
203 | return NULL; |
204 | } |
205 | |
206 | /* |
207 | * Add the tracepoint to the tracepoint hash table. Must be called with |
208 | * tracepoints_mutex held. |
209 | */ |
210 | static struct tracepoint_entry *add_tracepoint(const char *name) |
211 | { |
212 | struct hlist_head *head; |
213 | struct tracepoint_entry *e; |
214 | size_t name_len = strlen(name) + 1; |
215 | u32 hash = jhash(name, name_len-1, 0); |
216 | |
217 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
218 | hlist_for_each_entry(e, head, hlist) { |
219 | if (!strcmp(name, e->name)) { |
220 | printk(KERN_NOTICE |
221 | "tracepoint %s busy\n", name); |
222 | return ERR_PTR(-EEXIST); /* Already there */ |
223 | } |
224 | } |
225 | /* |
226 | * Using kmalloc here to allocate a variable length element. Could |
227 | * cause some memory fragmentation if overused. |
228 | */ |
229 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); |
230 | if (!e) |
231 | return ERR_PTR(-ENOMEM); |
232 | memcpy(&e->name[0], name, name_len); |
233 | e->funcs = NULL; |
234 | e->refcount = 0; |
235 | hlist_add_head(&e->hlist, head); |
236 | return e; |
237 | } |
238 | |
239 | /* |
240 | * Remove the tracepoint from the tracepoint hash table. Must be called with |
241 | * mutex_lock held. |
242 | */ |
243 | static inline void remove_tracepoint(struct tracepoint_entry *e) |
244 | { |
245 | hlist_del(&e->hlist); |
246 | kfree(e); |
247 | } |
248 | |
249 | /* |
250 | * Sets the probe callback corresponding to one tracepoint. |
251 | */ |
252 | static void set_tracepoint(struct tracepoint_entry **entry, |
253 | struct tracepoint *elem, int active) |
254 | { |
255 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); |
256 | |
257 | if (elem->regfunc && !static_key_enabled(&elem->key) && active) |
258 | elem->regfunc(); |
259 | else if (elem->unregfunc && static_key_enabled(&elem->key) && !active) |
260 | elem->unregfunc(); |
261 | |
262 | /* |
263 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new |
264 | * probe callbacks array is consistent before setting a pointer to it. |
265 | * This array is referenced by __DO_TRACE from |
266 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() |
267 | * is used. |
268 | */ |
269 | rcu_assign_pointer(elem->funcs, (*entry)->funcs); |
270 | if (active && !static_key_enabled(&elem->key)) |
271 | static_key_slow_inc(&elem->key); |
272 | else if (!active && static_key_enabled(&elem->key)) |
273 | static_key_slow_dec(&elem->key); |
274 | } |
275 | |
276 | /* |
277 | * Disable a tracepoint and its probe callback. |
278 | * Note: only waiting an RCU period after setting elem->call to the empty |
279 | * function insures that the original callback is not used anymore. This insured |
280 | * by preempt_disable around the call site. |
281 | */ |
282 | static void disable_tracepoint(struct tracepoint *elem) |
283 | { |
284 | if (elem->unregfunc && static_key_enabled(&elem->key)) |
285 | elem->unregfunc(); |
286 | |
287 | if (static_key_enabled(&elem->key)) |
288 | static_key_slow_dec(&elem->key); |
289 | rcu_assign_pointer(elem->funcs, NULL); |
290 | } |
291 | |
292 | /** |
293 | * tracepoint_update_probe_range - Update a probe range |
294 | * @begin: beginning of the range |
295 | * @end: end of the range |
296 | * |
297 | * Updates the probe callback corresponding to a range of tracepoints. |
298 | * Called with tracepoints_mutex held. |
299 | */ |
300 | static void tracepoint_update_probe_range(struct tracepoint * const *begin, |
301 | struct tracepoint * const *end) |
302 | { |
303 | struct tracepoint * const *iter; |
304 | struct tracepoint_entry *mark_entry; |
305 | |
306 | if (!begin) |
307 | return; |
308 | |
309 | for (iter = begin; iter < end; iter++) { |
310 | mark_entry = get_tracepoint((*iter)->name); |
311 | if (mark_entry) { |
312 | set_tracepoint(&mark_entry, *iter, |
313 | !!mark_entry->refcount); |
314 | } else { |
315 | disable_tracepoint(*iter); |
316 | } |
317 | } |
318 | } |
319 | |
320 | #ifdef CONFIG_MODULES |
321 | void module_update_tracepoints(void) |
322 | { |
323 | struct tp_module *tp_mod; |
324 | |
325 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) |
326 | tracepoint_update_probe_range(tp_mod->tracepoints_ptrs, |
327 | tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints); |
328 | } |
329 | #else /* CONFIG_MODULES */ |
330 | void module_update_tracepoints(void) |
331 | { |
332 | } |
333 | #endif /* CONFIG_MODULES */ |
334 | |
335 | |
336 | /* |
337 | * Update probes, removing the faulty probes. |
338 | * Called with tracepoints_mutex held. |
339 | */ |
340 | static void tracepoint_update_probes(void) |
341 | { |
342 | /* Core kernel tracepoints */ |
343 | tracepoint_update_probe_range(__start___tracepoints_ptrs, |
344 | __stop___tracepoints_ptrs); |
345 | /* tracepoints in modules. */ |
346 | module_update_tracepoints(); |
347 | } |
348 | |
349 | static struct tracepoint_func * |
350 | tracepoint_add_probe(const char *name, void *probe, void *data) |
351 | { |
352 | struct tracepoint_entry *entry; |
353 | struct tracepoint_func *old; |
354 | |
355 | entry = get_tracepoint(name); |
356 | if (!entry) { |
357 | entry = add_tracepoint(name); |
358 | if (IS_ERR(entry)) |
359 | return (struct tracepoint_func *)entry; |
360 | } |
361 | old = tracepoint_entry_add_probe(entry, probe, data); |
362 | if (IS_ERR(old) && !entry->refcount) |
363 | remove_tracepoint(entry); |
364 | return old; |
365 | } |
366 | |
367 | /** |
368 | * tracepoint_probe_register - Connect a probe to a tracepoint |
369 | * @name: tracepoint name |
370 | * @probe: probe handler |
371 | * |
372 | * Returns 0 if ok, error value on error. |
373 | * The probe address must at least be aligned on the architecture pointer size. |
374 | */ |
375 | int tracepoint_probe_register(const char *name, void *probe, void *data) |
376 | { |
377 | struct tracepoint_func *old; |
378 | |
379 | mutex_lock(&tracepoints_mutex); |
380 | old = tracepoint_add_probe(name, probe, data); |
381 | if (IS_ERR(old)) { |
382 | mutex_unlock(&tracepoints_mutex); |
383 | return PTR_ERR(old); |
384 | } |
385 | tracepoint_update_probes(); /* may update entry */ |
386 | mutex_unlock(&tracepoints_mutex); |
387 | release_probes(old); |
388 | return 0; |
389 | } |
390 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); |
391 | |
392 | static struct tracepoint_func * |
393 | tracepoint_remove_probe(const char *name, void *probe, void *data) |
394 | { |
395 | struct tracepoint_entry *entry; |
396 | struct tracepoint_func *old; |
397 | |
398 | entry = get_tracepoint(name); |
399 | if (!entry) |
400 | return ERR_PTR(-ENOENT); |
401 | old = tracepoint_entry_remove_probe(entry, probe, data); |
402 | if (IS_ERR(old)) |
403 | return old; |
404 | if (!entry->refcount) |
405 | remove_tracepoint(entry); |
406 | return old; |
407 | } |
408 | |
409 | /** |
410 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint |
411 | * @name: tracepoint name |
412 | * @probe: probe function pointer |
413 | * |
414 | * We do not need to call a synchronize_sched to make sure the probes have |
415 | * finished running before doing a module unload, because the module unload |
416 | * itself uses stop_machine(), which insures that every preempt disabled section |
417 | * have finished. |
418 | */ |
419 | int tracepoint_probe_unregister(const char *name, void *probe, void *data) |
420 | { |
421 | struct tracepoint_func *old; |
422 | |
423 | mutex_lock(&tracepoints_mutex); |
424 | old = tracepoint_remove_probe(name, probe, data); |
425 | if (IS_ERR(old)) { |
426 | mutex_unlock(&tracepoints_mutex); |
427 | return PTR_ERR(old); |
428 | } |
429 | tracepoint_update_probes(); /* may update entry */ |
430 | mutex_unlock(&tracepoints_mutex); |
431 | release_probes(old); |
432 | return 0; |
433 | } |
434 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); |
435 | |
436 | static LIST_HEAD(old_probes); |
437 | static int need_update; |
438 | |
439 | static void tracepoint_add_old_probes(void *old) |
440 | { |
441 | need_update = 1; |
442 | if (old) { |
443 | struct tp_probes *tp_probes = container_of(old, |
444 | struct tp_probes, probes[0]); |
445 | list_add(&tp_probes->u.list, &old_probes); |
446 | } |
447 | } |
448 | |
449 | /** |
450 | * tracepoint_probe_register_noupdate - register a probe but not connect |
451 | * @name: tracepoint name |
452 | * @probe: probe handler |
453 | * |
454 | * caller must call tracepoint_probe_update_all() |
455 | */ |
456 | int tracepoint_probe_register_noupdate(const char *name, void *probe, |
457 | void *data) |
458 | { |
459 | struct tracepoint_func *old; |
460 | |
461 | mutex_lock(&tracepoints_mutex); |
462 | old = tracepoint_add_probe(name, probe, data); |
463 | if (IS_ERR(old)) { |
464 | mutex_unlock(&tracepoints_mutex); |
465 | return PTR_ERR(old); |
466 | } |
467 | tracepoint_add_old_probes(old); |
468 | mutex_unlock(&tracepoints_mutex); |
469 | return 0; |
470 | } |
471 | EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); |
472 | |
473 | /** |
474 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect |
475 | * @name: tracepoint name |
476 | * @probe: probe function pointer |
477 | * |
478 | * caller must call tracepoint_probe_update_all() |
479 | */ |
480 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe, |
481 | void *data) |
482 | { |
483 | struct tracepoint_func *old; |
484 | |
485 | mutex_lock(&tracepoints_mutex); |
486 | old = tracepoint_remove_probe(name, probe, data); |
487 | if (IS_ERR(old)) { |
488 | mutex_unlock(&tracepoints_mutex); |
489 | return PTR_ERR(old); |
490 | } |
491 | tracepoint_add_old_probes(old); |
492 | mutex_unlock(&tracepoints_mutex); |
493 | return 0; |
494 | } |
495 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); |
496 | |
497 | /** |
498 | * tracepoint_probe_update_all - update tracepoints |
499 | */ |
500 | void tracepoint_probe_update_all(void) |
501 | { |
502 | LIST_HEAD(release_probes); |
503 | struct tp_probes *pos, *next; |
504 | |
505 | mutex_lock(&tracepoints_mutex); |
506 | if (!need_update) { |
507 | mutex_unlock(&tracepoints_mutex); |
508 | return; |
509 | } |
510 | if (!list_empty(&old_probes)) |
511 | list_replace_init(&old_probes, &release_probes); |
512 | need_update = 0; |
513 | tracepoint_update_probes(); |
514 | mutex_unlock(&tracepoints_mutex); |
515 | list_for_each_entry_safe(pos, next, &release_probes, u.list) { |
516 | list_del(&pos->u.list); |
517 | call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); |
518 | } |
519 | } |
520 | EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); |
521 | |
522 | /** |
523 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. |
524 | * @tracepoint: current tracepoints (in), next tracepoint (out) |
525 | * @begin: beginning of the range |
526 | * @end: end of the range |
527 | * |
528 | * Returns whether a next tracepoint has been found (1) or not (0). |
529 | * Will return the first tracepoint in the range if the input tracepoint is |
530 | * NULL. |
531 | */ |
532 | static int tracepoint_get_iter_range(struct tracepoint * const **tracepoint, |
533 | struct tracepoint * const *begin, struct tracepoint * const *end) |
534 | { |
535 | if (!*tracepoint && begin != end) { |
536 | *tracepoint = begin; |
537 | return 1; |
538 | } |
539 | if (*tracepoint >= begin && *tracepoint < end) |
540 | return 1; |
541 | return 0; |
542 | } |
543 | |
544 | #ifdef CONFIG_MODULES |
545 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
546 | { |
547 | int found = 0; |
548 | struct tp_module *iter_mod; |
549 | |
550 | /* Core kernel tracepoints */ |
551 | if (!iter->module) { |
552 | found = tracepoint_get_iter_range(&iter->tracepoint, |
553 | __start___tracepoints_ptrs, |
554 | __stop___tracepoints_ptrs); |
555 | if (found) |
556 | goto end; |
557 | } |
558 | /* Tracepoints in modules */ |
559 | mutex_lock(&tracepoints_mutex); |
560 | list_for_each_entry(iter_mod, &tracepoint_module_list, list) { |
561 | /* |
562 | * Sorted module list |
563 | */ |
564 | if (iter_mod < iter->module) |
565 | continue; |
566 | else if (iter_mod > iter->module) |
567 | iter->tracepoint = NULL; |
568 | found = tracepoint_get_iter_range(&iter->tracepoint, |
569 | iter_mod->tracepoints_ptrs, |
570 | iter_mod->tracepoints_ptrs |
571 | + iter_mod->num_tracepoints); |
572 | if (found) { |
573 | iter->module = iter_mod; |
574 | break; |
575 | } |
576 | } |
577 | mutex_unlock(&tracepoints_mutex); |
578 | end: |
579 | if (!found) |
580 | tracepoint_iter_reset(iter); |
581 | } |
582 | #else /* CONFIG_MODULES */ |
583 | static void tracepoint_get_iter(struct tracepoint_iter *iter) |
584 | { |
585 | int found = 0; |
586 | |
587 | /* Core kernel tracepoints */ |
588 | found = tracepoint_get_iter_range(&iter->tracepoint, |
589 | __start___tracepoints_ptrs, |
590 | __stop___tracepoints_ptrs); |
591 | if (!found) |
592 | tracepoint_iter_reset(iter); |
593 | } |
594 | #endif /* CONFIG_MODULES */ |
595 | |
596 | void tracepoint_iter_start(struct tracepoint_iter *iter) |
597 | { |
598 | tracepoint_get_iter(iter); |
599 | } |
600 | EXPORT_SYMBOL_GPL(tracepoint_iter_start); |
601 | |
602 | void tracepoint_iter_next(struct tracepoint_iter *iter) |
603 | { |
604 | iter->tracepoint++; |
605 | /* |
606 | * iter->tracepoint may be invalid because we blindly incremented it. |
607 | * Make sure it is valid by marshalling on the tracepoints, getting the |
608 | * tracepoints from following modules if necessary. |
609 | */ |
610 | tracepoint_get_iter(iter); |
611 | } |
612 | EXPORT_SYMBOL_GPL(tracepoint_iter_next); |
613 | |
614 | void tracepoint_iter_stop(struct tracepoint_iter *iter) |
615 | { |
616 | } |
617 | EXPORT_SYMBOL_GPL(tracepoint_iter_stop); |
618 | |
619 | void tracepoint_iter_reset(struct tracepoint_iter *iter) |
620 | { |
621 | #ifdef CONFIG_MODULES |
622 | iter->module = NULL; |
623 | #endif /* CONFIG_MODULES */ |
624 | iter->tracepoint = NULL; |
625 | } |
626 | EXPORT_SYMBOL_GPL(tracepoint_iter_reset); |
627 | |
628 | #ifdef CONFIG_MODULES |
629 | static int tracepoint_module_coming(struct module *mod) |
630 | { |
631 | struct tp_module *tp_mod, *iter; |
632 | int ret = 0; |
633 | |
634 | /* |
635 | * We skip modules that taint the kernel, especially those with different |
636 | * module headers (for forced load), to make sure we don't cause a crash. |
637 | * Staging and out-of-tree GPL modules are fine. |
638 | */ |
639 | if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP))) |
640 | return 0; |
641 | mutex_lock(&tracepoints_mutex); |
642 | tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); |
643 | if (!tp_mod) { |
644 | ret = -ENOMEM; |
645 | goto end; |
646 | } |
647 | tp_mod->num_tracepoints = mod->num_tracepoints; |
648 | tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs; |
649 | |
650 | /* |
651 | * tracepoint_module_list is kept sorted by struct module pointer |
652 | * address for iteration on tracepoints from a seq_file that can release |
653 | * the mutex between calls. |
654 | */ |
655 | list_for_each_entry_reverse(iter, &tracepoint_module_list, list) { |
656 | BUG_ON(iter == tp_mod); /* Should never be in the list twice */ |
657 | if (iter < tp_mod) { |
658 | /* We belong to the location right after iter. */ |
659 | list_add(&tp_mod->list, &iter->list); |
660 | goto module_added; |
661 | } |
662 | } |
663 | /* We belong to the beginning of the list */ |
664 | list_add(&tp_mod->list, &tracepoint_module_list); |
665 | module_added: |
666 | tracepoint_update_probe_range(mod->tracepoints_ptrs, |
667 | mod->tracepoints_ptrs + mod->num_tracepoints); |
668 | end: |
669 | mutex_unlock(&tracepoints_mutex); |
670 | return ret; |
671 | } |
672 | |
673 | static int tracepoint_module_going(struct module *mod) |
674 | { |
675 | struct tp_module *pos; |
676 | |
677 | mutex_lock(&tracepoints_mutex); |
678 | tracepoint_update_probe_range(mod->tracepoints_ptrs, |
679 | mod->tracepoints_ptrs + mod->num_tracepoints); |
680 | list_for_each_entry(pos, &tracepoint_module_list, list) { |
681 | if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) { |
682 | list_del(&pos->list); |
683 | kfree(pos); |
684 | break; |
685 | } |
686 | } |
687 | /* |
688 | * In the case of modules that were tainted at "coming", we'll simply |
689 | * walk through the list without finding it. We cannot use the "tainted" |
690 | * flag on "going", in case a module taints the kernel only after being |
691 | * loaded. |
692 | */ |
693 | mutex_unlock(&tracepoints_mutex); |
694 | return 0; |
695 | } |
696 | |
697 | int tracepoint_module_notify(struct notifier_block *self, |
698 | unsigned long val, void *data) |
699 | { |
700 | struct module *mod = data; |
701 | int ret = 0; |
702 | |
703 | switch (val) { |
704 | case MODULE_STATE_COMING: |
705 | ret = tracepoint_module_coming(mod); |
706 | break; |
707 | case MODULE_STATE_LIVE: |
708 | break; |
709 | case MODULE_STATE_GOING: |
710 | ret = tracepoint_module_going(mod); |
711 | break; |
712 | } |
713 | return ret; |
714 | } |
715 | |
716 | struct notifier_block tracepoint_module_nb = { |
717 | .notifier_call = tracepoint_module_notify, |
718 | .priority = 0, |
719 | }; |
720 | |
721 | static int init_tracepoints(void) |
722 | { |
723 | return register_module_notifier(&tracepoint_module_nb); |
724 | } |
725 | __initcall(init_tracepoints); |
726 | #endif /* CONFIG_MODULES */ |
727 | |
728 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
729 | |
730 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
731 | static int sys_tracepoint_refcount; |
732 | |
733 | void syscall_regfunc(void) |
734 | { |
735 | unsigned long flags; |
736 | struct task_struct *g, *t; |
737 | |
738 | if (!sys_tracepoint_refcount) { |
739 | read_lock_irqsave(&tasklist_lock, flags); |
740 | do_each_thread(g, t) { |
741 | /* Skip kernel threads. */ |
742 | if (t->mm) |
743 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
744 | } while_each_thread(g, t); |
745 | read_unlock_irqrestore(&tasklist_lock, flags); |
746 | } |
747 | sys_tracepoint_refcount++; |
748 | } |
749 | |
750 | void syscall_unregfunc(void) |
751 | { |
752 | unsigned long flags; |
753 | struct task_struct *g, *t; |
754 | |
755 | sys_tracepoint_refcount--; |
756 | if (!sys_tracepoint_refcount) { |
757 | read_lock_irqsave(&tasklist_lock, flags); |
758 | do_each_thread(g, t) { |
759 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
760 | } while_each_thread(g, t); |
761 | read_unlock_irqrestore(&tasklist_lock, flags); |
762 | } |
763 | } |
764 | #endif |
765 |
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