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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 { |
0dea6d52 | 70 | struct rcu_head rcu; |
38516ab5 | 71 | struct tracepoint_func probes[0]; |
19dba33c | 72 | }; |
97e1c18e | 73 | |
19dba33c | 74 | static inline void *allocate_probes(int count) |
97e1c18e | 75 | { |
38516ab5 | 76 | struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) |
19dba33c LJ |
77 | + sizeof(struct tp_probes), GFP_KERNEL); |
78 | return p == NULL ? NULL : p->probes; | |
97e1c18e MD |
79 | } |
80 | ||
19dba33c | 81 | static void rcu_free_old_probes(struct rcu_head *head) |
97e1c18e | 82 | { |
0dea6d52 | 83 | kfree(container_of(head, struct tp_probes, rcu)); |
19dba33c LJ |
84 | } |
85 | ||
38516ab5 | 86 | static inline void release_probes(struct tracepoint_func *old) |
19dba33c LJ |
87 | { |
88 | if (old) { | |
89 | struct tp_probes *tp_probes = container_of(old, | |
90 | struct tp_probes, probes[0]); | |
0dea6d52 | 91 | call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes); |
19dba33c | 92 | } |
97e1c18e MD |
93 | } |
94 | ||
95 | static void debug_print_probes(struct tracepoint_entry *entry) | |
96 | { | |
97 | int i; | |
98 | ||
19dba33c | 99 | if (!tracepoint_debug || !entry->funcs) |
97e1c18e MD |
100 | return; |
101 | ||
38516ab5 SR |
102 | for (i = 0; entry->funcs[i].func; i++) |
103 | printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func); | |
97e1c18e MD |
104 | } |
105 | ||
38516ab5 SR |
106 | static struct tracepoint_func * |
107 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, | |
108 | void *probe, void *data) | |
97e1c18e MD |
109 | { |
110 | int nr_probes = 0; | |
38516ab5 | 111 | struct tracepoint_func *old, *new; |
97e1c18e | 112 | |
4c69e6ea S |
113 | if (WARN_ON(!probe)) |
114 | return ERR_PTR(-EINVAL); | |
97e1c18e MD |
115 | |
116 | debug_print_probes(entry); | |
117 | old = entry->funcs; | |
118 | if (old) { | |
119 | /* (N -> N+1), (N != 0, 1) probes */ | |
38516ab5 SR |
120 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
121 | if (old[nr_probes].func == probe && | |
122 | old[nr_probes].data == data) | |
97e1c18e MD |
123 | return ERR_PTR(-EEXIST); |
124 | } | |
125 | /* + 2 : one for new probe, one for NULL func */ | |
19dba33c | 126 | new = allocate_probes(nr_probes + 2); |
97e1c18e MD |
127 | if (new == NULL) |
128 | return ERR_PTR(-ENOMEM); | |
129 | if (old) | |
38516ab5 SR |
130 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); |
131 | new[nr_probes].func = probe; | |
132 | new[nr_probes].data = data; | |
133 | new[nr_probes + 1].func = NULL; | |
97e1c18e MD |
134 | entry->refcount = nr_probes + 1; |
135 | entry->funcs = new; | |
136 | debug_print_probes(entry); | |
137 | return old; | |
138 | } | |
139 | ||
140 | static void * | |
38516ab5 SR |
141 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, |
142 | void *probe, void *data) | |
97e1c18e MD |
143 | { |
144 | int nr_probes = 0, nr_del = 0, i; | |
38516ab5 | 145 | struct tracepoint_func *old, *new; |
97e1c18e MD |
146 | |
147 | old = entry->funcs; | |
148 | ||
f66af459 | 149 | if (!old) |
19dba33c | 150 | return ERR_PTR(-ENOENT); |
f66af459 | 151 | |
97e1c18e MD |
152 | debug_print_probes(entry); |
153 | /* (N -> M), (N > 1, M >= 0) probes */ | |
4c69e6ea S |
154 | if (probe) { |
155 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { | |
156 | if (old[nr_probes].func == probe && | |
157 | old[nr_probes].data == data) | |
158 | nr_del++; | |
159 | } | |
97e1c18e MD |
160 | } |
161 | ||
4c69e6ea S |
162 | /* |
163 | * If probe is NULL, then nr_probes = nr_del = 0, and then the | |
164 | * entire entry will be removed. | |
165 | */ | |
97e1c18e MD |
166 | if (nr_probes - nr_del == 0) { |
167 | /* N -> 0, (N > 1) */ | |
168 | entry->funcs = NULL; | |
169 | entry->refcount = 0; | |
170 | debug_print_probes(entry); | |
171 | return old; | |
172 | } else { | |
173 | int j = 0; | |
174 | /* N -> M, (N > 1, M > 0) */ | |
175 | /* + 1 for NULL */ | |
19dba33c | 176 | new = allocate_probes(nr_probes - nr_del + 1); |
97e1c18e MD |
177 | if (new == NULL) |
178 | return ERR_PTR(-ENOMEM); | |
38516ab5 | 179 | for (i = 0; old[i].func; i++) |
4c69e6ea | 180 | if (old[i].func != probe || old[i].data != data) |
97e1c18e | 181 | new[j++] = old[i]; |
38516ab5 | 182 | new[nr_probes - nr_del].func = NULL; |
97e1c18e MD |
183 | entry->refcount = nr_probes - nr_del; |
184 | entry->funcs = new; | |
185 | } | |
186 | debug_print_probes(entry); | |
187 | return old; | |
188 | } | |
189 | ||
190 | /* | |
191 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. | |
192 | * Must be called with tracepoints_mutex held. | |
193 | * Returns NULL if not present. | |
194 | */ | |
195 | static struct tracepoint_entry *get_tracepoint(const char *name) | |
196 | { | |
197 | struct hlist_head *head; | |
97e1c18e MD |
198 | struct tracepoint_entry *e; |
199 | u32 hash = jhash(name, strlen(name), 0); | |
200 | ||
9795302a | 201 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
b67bfe0d | 202 | hlist_for_each_entry(e, head, hlist) { |
97e1c18e MD |
203 | if (!strcmp(name, e->name)) |
204 | return e; | |
205 | } | |
206 | return NULL; | |
207 | } | |
208 | ||
209 | /* | |
210 | * Add the tracepoint to the tracepoint hash table. Must be called with | |
211 | * tracepoints_mutex held. | |
212 | */ | |
213 | static struct tracepoint_entry *add_tracepoint(const char *name) | |
214 | { | |
215 | struct hlist_head *head; | |
97e1c18e MD |
216 | struct tracepoint_entry *e; |
217 | size_t name_len = strlen(name) + 1; | |
218 | u32 hash = jhash(name, name_len-1, 0); | |
219 | ||
9795302a | 220 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; |
b67bfe0d | 221 | hlist_for_each_entry(e, head, hlist) { |
97e1c18e MD |
222 | if (!strcmp(name, e->name)) { |
223 | printk(KERN_NOTICE | |
224 | "tracepoint %s busy\n", name); | |
225 | return ERR_PTR(-EEXIST); /* Already there */ | |
226 | } | |
227 | } | |
228 | /* | |
229 | * Using kmalloc here to allocate a variable length element. Could | |
230 | * cause some memory fragmentation if overused. | |
231 | */ | |
232 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); | |
233 | if (!e) | |
234 | return ERR_PTR(-ENOMEM); | |
235 | memcpy(&e->name[0], name, name_len); | |
236 | e->funcs = NULL; | |
237 | e->refcount = 0; | |
b196e2b9 | 238 | e->enabled = 0; |
97e1c18e MD |
239 | hlist_add_head(&e->hlist, head); |
240 | return e; | |
241 | } | |
242 | ||
243 | /* | |
244 | * Remove the tracepoint from the tracepoint hash table. Must be called with | |
245 | * mutex_lock held. | |
246 | */ | |
19dba33c | 247 | static inline void remove_tracepoint(struct tracepoint_entry *e) |
97e1c18e | 248 | { |
97e1c18e | 249 | hlist_del(&e->hlist); |
97e1c18e | 250 | kfree(e); |
97e1c18e MD |
251 | } |
252 | ||
253 | /* | |
254 | * Sets the probe callback corresponding to one tracepoint. | |
255 | */ | |
256 | static void set_tracepoint(struct tracepoint_entry **entry, | |
257 | struct tracepoint *elem, int active) | |
258 | { | |
259 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); | |
260 | ||
c5905afb | 261 | if (elem->regfunc && !static_key_enabled(&elem->key) && active) |
97419875 | 262 | elem->regfunc(); |
c5905afb | 263 | else if (elem->unregfunc && static_key_enabled(&elem->key) && !active) |
97419875 JS |
264 | elem->unregfunc(); |
265 | ||
97e1c18e MD |
266 | /* |
267 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new | |
268 | * probe callbacks array is consistent before setting a pointer to it. | |
269 | * This array is referenced by __DO_TRACE from | |
270 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() | |
271 | * is used. | |
272 | */ | |
273 | rcu_assign_pointer(elem->funcs, (*entry)->funcs); | |
c5905afb IM |
274 | if (active && !static_key_enabled(&elem->key)) |
275 | static_key_slow_inc(&elem->key); | |
276 | else if (!active && static_key_enabled(&elem->key)) | |
277 | static_key_slow_dec(&elem->key); | |
97e1c18e MD |
278 | } |
279 | ||
280 | /* | |
281 | * Disable a tracepoint and its probe callback. | |
282 | * Note: only waiting an RCU period after setting elem->call to the empty | |
283 | * function insures that the original callback is not used anymore. This insured | |
284 | * by preempt_disable around the call site. | |
285 | */ | |
286 | static void disable_tracepoint(struct tracepoint *elem) | |
287 | { | |
c5905afb | 288 | if (elem->unregfunc && static_key_enabled(&elem->key)) |
97419875 JS |
289 | elem->unregfunc(); |
290 | ||
c5905afb IM |
291 | if (static_key_enabled(&elem->key)) |
292 | static_key_slow_dec(&elem->key); | |
de0baf9a | 293 | rcu_assign_pointer(elem->funcs, NULL); |
97e1c18e MD |
294 | } |
295 | ||
296 | /** | |
297 | * tracepoint_update_probe_range - Update a probe range | |
298 | * @begin: beginning of the range | |
299 | * @end: end of the range | |
300 | * | |
301 | * Updates the probe callback corresponding to a range of tracepoints. | |
b75ef8b4 | 302 | * Called with tracepoints_mutex held. |
97e1c18e | 303 | */ |
b75ef8b4 MD |
304 | static void tracepoint_update_probe_range(struct tracepoint * const *begin, |
305 | struct tracepoint * const *end) | |
97e1c18e | 306 | { |
65498646 | 307 | struct tracepoint * const *iter; |
97e1c18e MD |
308 | struct tracepoint_entry *mark_entry; |
309 | ||
ec625cb2 | 310 | if (!begin) |
09933a10 | 311 | return; |
09933a10 | 312 | |
97e1c18e | 313 | for (iter = begin; iter < end; iter++) { |
65498646 | 314 | mark_entry = get_tracepoint((*iter)->name); |
97e1c18e | 315 | if (mark_entry) { |
65498646 | 316 | set_tracepoint(&mark_entry, *iter, |
97e1c18e | 317 | !!mark_entry->refcount); |
b196e2b9 | 318 | mark_entry->enabled = !!mark_entry->refcount; |
97e1c18e | 319 | } else { |
65498646 | 320 | disable_tracepoint(*iter); |
97e1c18e MD |
321 | } |
322 | } | |
97e1c18e MD |
323 | } |
324 | ||
b75ef8b4 MD |
325 | #ifdef CONFIG_MODULES |
326 | void module_update_tracepoints(void) | |
327 | { | |
328 | struct tp_module *tp_mod; | |
329 | ||
330 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) | |
331 | tracepoint_update_probe_range(tp_mod->tracepoints_ptrs, | |
332 | tp_mod->tracepoints_ptrs + tp_mod->num_tracepoints); | |
333 | } | |
334 | #else /* CONFIG_MODULES */ | |
335 | void module_update_tracepoints(void) | |
336 | { | |
337 | } | |
338 | #endif /* CONFIG_MODULES */ | |
339 | ||
340 | ||
97e1c18e MD |
341 | /* |
342 | * Update probes, removing the faulty probes. | |
b75ef8b4 | 343 | * Called with tracepoints_mutex held. |
97e1c18e MD |
344 | */ |
345 | static void tracepoint_update_probes(void) | |
346 | { | |
347 | /* Core kernel tracepoints */ | |
65498646 MD |
348 | tracepoint_update_probe_range(__start___tracepoints_ptrs, |
349 | __stop___tracepoints_ptrs); | |
97e1c18e MD |
350 | /* tracepoints in modules. */ |
351 | module_update_tracepoints(); | |
352 | } | |
353 | ||
38516ab5 SR |
354 | static struct tracepoint_func * |
355 | tracepoint_add_probe(const char *name, void *probe, void *data) | |
127cafbb LJ |
356 | { |
357 | struct tracepoint_entry *entry; | |
38516ab5 | 358 | struct tracepoint_func *old; |
127cafbb LJ |
359 | |
360 | entry = get_tracepoint(name); | |
361 | if (!entry) { | |
362 | entry = add_tracepoint(name); | |
363 | if (IS_ERR(entry)) | |
38516ab5 | 364 | return (struct tracepoint_func *)entry; |
127cafbb | 365 | } |
38516ab5 | 366 | old = tracepoint_entry_add_probe(entry, probe, data); |
127cafbb LJ |
367 | if (IS_ERR(old) && !entry->refcount) |
368 | remove_tracepoint(entry); | |
369 | return old; | |
370 | } | |
371 | ||
97e1c18e MD |
372 | /** |
373 | * tracepoint_probe_register - Connect a probe to a tracepoint | |
374 | * @name: tracepoint name | |
375 | * @probe: probe handler | |
4c11628a | 376 | * @data: probe private data |
97e1c18e | 377 | * |
3bbc8db3 MD |
378 | * Returns: |
379 | * - 0 if the probe was successfully registered, and tracepoint | |
380 | * callsites are currently loaded for that probe, | |
381 | * - -ENODEV if the probe was successfully registered, but no tracepoint | |
382 | * callsite is currently loaded for that probe, | |
383 | * - other negative error value on error. | |
384 | * | |
385 | * When tracepoint_probe_register() returns either 0 or -ENODEV, | |
386 | * parameters @name, @probe, and @data may be used by the tracepoint | |
387 | * infrastructure until the probe is unregistered. | |
97e1c18e | 388 | * |
97e1c18e MD |
389 | * The probe address must at least be aligned on the architecture pointer size. |
390 | */ | |
38516ab5 | 391 | int tracepoint_probe_register(const char *name, void *probe, void *data) |
97e1c18e | 392 | { |
38516ab5 | 393 | struct tracepoint_func *old; |
b196e2b9 SR |
394 | struct tracepoint_entry *entry; |
395 | int ret = 0; | |
97e1c18e MD |
396 | |
397 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 398 | old = tracepoint_add_probe(name, probe, data); |
b75ef8b4 MD |
399 | if (IS_ERR(old)) { |
400 | mutex_unlock(&tracepoints_mutex); | |
127cafbb | 401 | return PTR_ERR(old); |
b75ef8b4 | 402 | } |
97e1c18e | 403 | tracepoint_update_probes(); /* may update entry */ |
b196e2b9 SR |
404 | entry = get_tracepoint(name); |
405 | /* Make sure the entry was enabled */ | |
406 | if (!entry || !entry->enabled) | |
407 | ret = -ENODEV; | |
b75ef8b4 | 408 | mutex_unlock(&tracepoints_mutex); |
19dba33c | 409 | release_probes(old); |
b196e2b9 | 410 | return ret; |
97e1c18e MD |
411 | } |
412 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); | |
413 | ||
38516ab5 SR |
414 | static struct tracepoint_func * |
415 | tracepoint_remove_probe(const char *name, void *probe, void *data) | |
127cafbb LJ |
416 | { |
417 | struct tracepoint_entry *entry; | |
38516ab5 | 418 | struct tracepoint_func *old; |
127cafbb LJ |
419 | |
420 | entry = get_tracepoint(name); | |
421 | if (!entry) | |
422 | return ERR_PTR(-ENOENT); | |
38516ab5 | 423 | old = tracepoint_entry_remove_probe(entry, probe, data); |
127cafbb LJ |
424 | if (IS_ERR(old)) |
425 | return old; | |
426 | if (!entry->refcount) | |
427 | remove_tracepoint(entry); | |
428 | return old; | |
429 | } | |
430 | ||
97e1c18e MD |
431 | /** |
432 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint | |
433 | * @name: tracepoint name | |
434 | * @probe: probe function pointer | |
4c11628a | 435 | * @data: probe private data |
97e1c18e MD |
436 | * |
437 | * We do not need to call a synchronize_sched to make sure the probes have | |
438 | * finished running before doing a module unload, because the module unload | |
439 | * itself uses stop_machine(), which insures that every preempt disabled section | |
440 | * have finished. | |
441 | */ | |
38516ab5 | 442 | int tracepoint_probe_unregister(const char *name, void *probe, void *data) |
97e1c18e | 443 | { |
38516ab5 | 444 | struct tracepoint_func *old; |
97e1c18e MD |
445 | |
446 | mutex_lock(&tracepoints_mutex); | |
38516ab5 | 447 | old = tracepoint_remove_probe(name, probe, data); |
b75ef8b4 MD |
448 | if (IS_ERR(old)) { |
449 | mutex_unlock(&tracepoints_mutex); | |
127cafbb | 450 | return PTR_ERR(old); |
b75ef8b4 | 451 | } |
97e1c18e | 452 | tracepoint_update_probes(); /* may update entry */ |
b75ef8b4 | 453 | mutex_unlock(&tracepoints_mutex); |
19dba33c LJ |
454 | release_probes(old); |
455 | return 0; | |
97e1c18e MD |
456 | } |
457 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); | |
458 | ||
32f85742 | 459 | |
227a8375 | 460 | #ifdef CONFIG_MODULES |
45ab2813 SRRH |
461 | bool trace_module_has_bad_taint(struct module *mod) |
462 | { | |
463 | return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP)); | |
464 | } | |
465 | ||
b75ef8b4 MD |
466 | static int tracepoint_module_coming(struct module *mod) |
467 | { | |
0dea6d52 | 468 | struct tp_module *tp_mod; |
b75ef8b4 MD |
469 | int ret = 0; |
470 | ||
7dec935a SRRH |
471 | if (!mod->num_tracepoints) |
472 | return 0; | |
473 | ||
b75ef8b4 | 474 | /* |
c10076c4 SR |
475 | * We skip modules that taint the kernel, especially those with different |
476 | * module headers (for forced load), to make sure we don't cause a crash. | |
477 | * Staging and out-of-tree GPL modules are fine. | |
b75ef8b4 | 478 | */ |
45ab2813 | 479 | if (trace_module_has_bad_taint(mod)) |
b75ef8b4 MD |
480 | return 0; |
481 | mutex_lock(&tracepoints_mutex); | |
482 | tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); | |
483 | if (!tp_mod) { | |
484 | ret = -ENOMEM; | |
485 | goto end; | |
486 | } | |
487 | tp_mod->num_tracepoints = mod->num_tracepoints; | |
488 | tp_mod->tracepoints_ptrs = mod->tracepoints_ptrs; | |
0dea6d52 | 489 | list_add_tail(&tp_mod->list, &tracepoint_module_list); |
b75ef8b4 MD |
490 | tracepoint_update_probe_range(mod->tracepoints_ptrs, |
491 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
492 | end: | |
493 | mutex_unlock(&tracepoints_mutex); | |
494 | return ret; | |
495 | } | |
496 | ||
497 | static int tracepoint_module_going(struct module *mod) | |
498 | { | |
499 | struct tp_module *pos; | |
500 | ||
7dec935a SRRH |
501 | if (!mod->num_tracepoints) |
502 | return 0; | |
503 | ||
b75ef8b4 MD |
504 | mutex_lock(&tracepoints_mutex); |
505 | tracepoint_update_probe_range(mod->tracepoints_ptrs, | |
506 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
507 | list_for_each_entry(pos, &tracepoint_module_list, list) { | |
508 | if (pos->tracepoints_ptrs == mod->tracepoints_ptrs) { | |
509 | list_del(&pos->list); | |
510 | kfree(pos); | |
511 | break; | |
512 | } | |
513 | } | |
514 | /* | |
515 | * In the case of modules that were tainted at "coming", we'll simply | |
516 | * walk through the list without finding it. We cannot use the "tainted" | |
517 | * flag on "going", in case a module taints the kernel only after being | |
518 | * loaded. | |
519 | */ | |
520 | mutex_unlock(&tracepoints_mutex); | |
521 | return 0; | |
522 | } | |
227a8375 | 523 | |
32f85742 MD |
524 | int tracepoint_module_notify(struct notifier_block *self, |
525 | unsigned long val, void *data) | |
526 | { | |
527 | struct module *mod = data; | |
b75ef8b4 | 528 | int ret = 0; |
32f85742 MD |
529 | |
530 | switch (val) { | |
531 | case MODULE_STATE_COMING: | |
b75ef8b4 MD |
532 | ret = tracepoint_module_coming(mod); |
533 | break; | |
534 | case MODULE_STATE_LIVE: | |
535 | break; | |
32f85742 | 536 | case MODULE_STATE_GOING: |
b75ef8b4 | 537 | ret = tracepoint_module_going(mod); |
32f85742 MD |
538 | break; |
539 | } | |
b75ef8b4 | 540 | return ret; |
32f85742 MD |
541 | } |
542 | ||
543 | struct notifier_block tracepoint_module_nb = { | |
544 | .notifier_call = tracepoint_module_notify, | |
545 | .priority = 0, | |
546 | }; | |
547 | ||
548 | static int init_tracepoints(void) | |
549 | { | |
550 | return register_module_notifier(&tracepoint_module_nb); | |
551 | } | |
552 | __initcall(init_tracepoints); | |
227a8375 | 553 | #endif /* CONFIG_MODULES */ |
a871bd33 | 554 | |
3d27d8cb | 555 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
60d970c2 | 556 | |
97419875 | 557 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
a871bd33 JB |
558 | static int sys_tracepoint_refcount; |
559 | ||
560 | void syscall_regfunc(void) | |
561 | { | |
562 | unsigned long flags; | |
563 | struct task_struct *g, *t; | |
564 | ||
a871bd33 JB |
565 | if (!sys_tracepoint_refcount) { |
566 | read_lock_irqsave(&tasklist_lock, flags); | |
567 | do_each_thread(g, t) { | |
cc3b13c1 HB |
568 | /* Skip kernel threads. */ |
569 | if (t->mm) | |
570 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); | |
a871bd33 JB |
571 | } while_each_thread(g, t); |
572 | read_unlock_irqrestore(&tasklist_lock, flags); | |
573 | } | |
574 | sys_tracepoint_refcount++; | |
a871bd33 JB |
575 | } |
576 | ||
577 | void syscall_unregfunc(void) | |
578 | { | |
579 | unsigned long flags; | |
580 | struct task_struct *g, *t; | |
581 | ||
a871bd33 JB |
582 | sys_tracepoint_refcount--; |
583 | if (!sys_tracepoint_refcount) { | |
584 | read_lock_irqsave(&tasklist_lock, flags); | |
585 | do_each_thread(g, t) { | |
66700001 | 586 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
a871bd33 JB |
587 | } while_each_thread(g, t); |
588 | read_unlock_irqrestore(&tasklist_lock, flags); | |
589 | } | |
a871bd33 | 590 | } |
60d970c2 | 591 | #endif |