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97e1c18e | 1 | /* |
de7b2973 | 2 | * Copyright (C) 2008-2014 Mathieu Desnoyers |
97e1c18e MD |
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 | ||
de7b2973 | 36 | #ifdef CONFIG_MODULES |
97e1c18e | 37 | /* |
de7b2973 | 38 | * Tracepoint module list mutex protects the local module list. |
97e1c18e | 39 | */ |
de7b2973 | 40 | static DEFINE_MUTEX(tracepoint_module_list_mutex); |
97e1c18e | 41 | |
de7b2973 | 42 | /* Local list of struct tp_module */ |
b75ef8b4 MD |
43 | static LIST_HEAD(tracepoint_module_list); |
44 | #endif /* CONFIG_MODULES */ | |
45 | ||
97e1c18e | 46 | /* |
de7b2973 MD |
47 | * tracepoints_mutex protects the builtin and module tracepoints. |
48 | * tracepoints_mutex nests inside tracepoint_module_list_mutex. | |
97e1c18e | 49 | */ |
de7b2973 | 50 | static DEFINE_MUTEX(tracepoints_mutex); |
97e1c18e MD |
51 | |
52 | /* | |
53 | * Note about RCU : | |
fd589a8f | 54 | * It is used to delay the free of multiple probes array until a quiescent |
97e1c18e | 55 | * state is reached. |
97e1c18e | 56 | */ |
19dba33c | 57 | struct tp_probes { |
0dea6d52 | 58 | struct rcu_head rcu; |
38516ab5 | 59 | struct tracepoint_func probes[0]; |
19dba33c | 60 | }; |
97e1c18e | 61 | |
19dba33c | 62 | static inline void *allocate_probes(int count) |
97e1c18e | 63 | { |
38516ab5 | 64 | struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) |
19dba33c LJ |
65 | + sizeof(struct tp_probes), GFP_KERNEL); |
66 | return p == NULL ? NULL : p->probes; | |
97e1c18e MD |
67 | } |
68 | ||
19dba33c | 69 | static void rcu_free_old_probes(struct rcu_head *head) |
97e1c18e | 70 | { |
0dea6d52 | 71 | kfree(container_of(head, struct tp_probes, rcu)); |
19dba33c LJ |
72 | } |
73 | ||
38516ab5 | 74 | static inline void release_probes(struct tracepoint_func *old) |
19dba33c LJ |
75 | { |
76 | if (old) { | |
77 | struct tp_probes *tp_probes = container_of(old, | |
78 | struct tp_probes, probes[0]); | |
0dea6d52 | 79 | call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes); |
19dba33c | 80 | } |
97e1c18e MD |
81 | } |
82 | ||
de7b2973 | 83 | static void debug_print_probes(struct tracepoint_func *funcs) |
97e1c18e MD |
84 | { |
85 | int i; | |
86 | ||
de7b2973 | 87 | if (!tracepoint_debug || !funcs) |
97e1c18e MD |
88 | return; |
89 | ||
de7b2973 MD |
90 | for (i = 0; funcs[i].func; i++) |
91 | printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func); | |
97e1c18e MD |
92 | } |
93 | ||
de7b2973 MD |
94 | static struct tracepoint_func *func_add(struct tracepoint_func **funcs, |
95 | struct tracepoint_func *tp_func) | |
97e1c18e MD |
96 | { |
97 | int nr_probes = 0; | |
38516ab5 | 98 | struct tracepoint_func *old, *new; |
97e1c18e | 99 | |
de7b2973 | 100 | if (WARN_ON(!tp_func->func)) |
4c69e6ea | 101 | return ERR_PTR(-EINVAL); |
97e1c18e | 102 | |
de7b2973 MD |
103 | debug_print_probes(*funcs); |
104 | old = *funcs; | |
97e1c18e MD |
105 | if (old) { |
106 | /* (N -> N+1), (N != 0, 1) probes */ | |
38516ab5 | 107 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) |
de7b2973 MD |
108 | if (old[nr_probes].func == tp_func->func && |
109 | old[nr_probes].data == tp_func->data) | |
97e1c18e MD |
110 | return ERR_PTR(-EEXIST); |
111 | } | |
112 | /* + 2 : one for new probe, one for NULL func */ | |
19dba33c | 113 | new = allocate_probes(nr_probes + 2); |
97e1c18e MD |
114 | if (new == NULL) |
115 | return ERR_PTR(-ENOMEM); | |
116 | if (old) | |
38516ab5 | 117 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); |
de7b2973 | 118 | new[nr_probes] = *tp_func; |
38516ab5 | 119 | new[nr_probes + 1].func = NULL; |
de7b2973 MD |
120 | *funcs = new; |
121 | debug_print_probes(*funcs); | |
97e1c18e MD |
122 | return old; |
123 | } | |
124 | ||
de7b2973 MD |
125 | static void *func_remove(struct tracepoint_func **funcs, |
126 | struct tracepoint_func *tp_func) | |
97e1c18e MD |
127 | { |
128 | int nr_probes = 0, nr_del = 0, i; | |
38516ab5 | 129 | struct tracepoint_func *old, *new; |
97e1c18e | 130 | |
de7b2973 | 131 | old = *funcs; |
97e1c18e | 132 | |
f66af459 | 133 | if (!old) |
19dba33c | 134 | return ERR_PTR(-ENOENT); |
f66af459 | 135 | |
de7b2973 | 136 | debug_print_probes(*funcs); |
97e1c18e | 137 | /* (N -> M), (N > 1, M >= 0) probes */ |
de7b2973 | 138 | if (tp_func->func) { |
4c69e6ea | 139 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { |
de7b2973 MD |
140 | if (old[nr_probes].func == tp_func->func && |
141 | old[nr_probes].data == tp_func->data) | |
4c69e6ea S |
142 | nr_del++; |
143 | } | |
97e1c18e MD |
144 | } |
145 | ||
4c69e6ea S |
146 | /* |
147 | * If probe is NULL, then nr_probes = nr_del = 0, and then the | |
148 | * entire entry will be removed. | |
149 | */ | |
97e1c18e MD |
150 | if (nr_probes - nr_del == 0) { |
151 | /* N -> 0, (N > 1) */ | |
de7b2973 MD |
152 | *funcs = NULL; |
153 | debug_print_probes(*funcs); | |
97e1c18e MD |
154 | return old; |
155 | } else { | |
156 | int j = 0; | |
157 | /* N -> M, (N > 1, M > 0) */ | |
158 | /* + 1 for NULL */ | |
19dba33c | 159 | new = allocate_probes(nr_probes - nr_del + 1); |
97e1c18e MD |
160 | if (new == NULL) |
161 | return ERR_PTR(-ENOMEM); | |
38516ab5 | 162 | for (i = 0; old[i].func; i++) |
de7b2973 MD |
163 | if (old[i].func != tp_func->func |
164 | || old[i].data != tp_func->data) | |
97e1c18e | 165 | new[j++] = old[i]; |
38516ab5 | 166 | new[nr_probes - nr_del].func = NULL; |
de7b2973 | 167 | *funcs = new; |
97e1c18e | 168 | } |
de7b2973 | 169 | debug_print_probes(*funcs); |
97e1c18e MD |
170 | return old; |
171 | } | |
172 | ||
173 | /* | |
de7b2973 | 174 | * Add the probe function to a tracepoint. |
97e1c18e | 175 | */ |
de7b2973 MD |
176 | static int tracepoint_add_func(struct tracepoint *tp, |
177 | struct tracepoint_func *func) | |
97e1c18e | 178 | { |
de7b2973 | 179 | struct tracepoint_func *old, *tp_funcs; |
97e1c18e | 180 | |
de7b2973 MD |
181 | if (tp->regfunc && !static_key_enabled(&tp->key)) |
182 | tp->regfunc(); | |
97e1c18e | 183 | |
b725dfea MD |
184 | tp_funcs = rcu_dereference_protected(tp->funcs, |
185 | lockdep_is_held(&tracepoints_mutex)); | |
de7b2973 MD |
186 | old = func_add(&tp_funcs, func); |
187 | if (IS_ERR(old)) { | |
188 | WARN_ON_ONCE(1); | |
189 | return PTR_ERR(old); | |
190 | } | |
97419875 | 191 | |
97e1c18e MD |
192 | /* |
193 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new | |
194 | * probe callbacks array is consistent before setting a pointer to it. | |
195 | * This array is referenced by __DO_TRACE from | |
196 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() | |
197 | * is used. | |
198 | */ | |
de7b2973 MD |
199 | rcu_assign_pointer(tp->funcs, tp_funcs); |
200 | if (!static_key_enabled(&tp->key)) | |
201 | static_key_slow_inc(&tp->key); | |
8058bd0f | 202 | release_probes(old); |
de7b2973 | 203 | return 0; |
97e1c18e MD |
204 | } |
205 | ||
206 | /* | |
de7b2973 | 207 | * Remove a probe function from a tracepoint. |
97e1c18e MD |
208 | * Note: only waiting an RCU period after setting elem->call to the empty |
209 | * function insures that the original callback is not used anymore. This insured | |
210 | * by preempt_disable around the call site. | |
211 | */ | |
de7b2973 MD |
212 | static int tracepoint_remove_func(struct tracepoint *tp, |
213 | struct tracepoint_func *func) | |
97e1c18e | 214 | { |
de7b2973 | 215 | struct tracepoint_func *old, *tp_funcs; |
97e1c18e | 216 | |
b725dfea MD |
217 | tp_funcs = rcu_dereference_protected(tp->funcs, |
218 | lockdep_is_held(&tracepoints_mutex)); | |
de7b2973 MD |
219 | old = func_remove(&tp_funcs, func); |
220 | if (IS_ERR(old)) { | |
221 | WARN_ON_ONCE(1); | |
222 | return PTR_ERR(old); | |
97e1c18e | 223 | } |
b75ef8b4 | 224 | |
de7b2973 MD |
225 | if (!tp_funcs) { |
226 | /* Removed last function */ | |
227 | if (tp->unregfunc && static_key_enabled(&tp->key)) | |
228 | tp->unregfunc(); | |
b75ef8b4 | 229 | |
de7b2973 MD |
230 | if (static_key_enabled(&tp->key)) |
231 | static_key_slow_dec(&tp->key); | |
127cafbb | 232 | } |
de7b2973 | 233 | rcu_assign_pointer(tp->funcs, tp_funcs); |
8058bd0f | 234 | release_probes(old); |
de7b2973 | 235 | return 0; |
127cafbb LJ |
236 | } |
237 | ||
97e1c18e MD |
238 | /** |
239 | * tracepoint_probe_register - Connect a probe to a tracepoint | |
de7b2973 | 240 | * @tp: tracepoint |
97e1c18e | 241 | * @probe: probe handler |
cac92ba7 | 242 | * @data: tracepoint data |
97e1c18e | 243 | * |
de7b2973 MD |
244 | * Returns 0 if ok, error value on error. |
245 | * Note: if @tp is within a module, the caller is responsible for | |
246 | * unregistering the probe before the module is gone. This can be | |
247 | * performed either with a tracepoint module going notifier, or from | |
248 | * within module exit functions. | |
97e1c18e | 249 | */ |
de7b2973 | 250 | int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data) |
97e1c18e | 251 | { |
de7b2973 MD |
252 | struct tracepoint_func tp_func; |
253 | int ret; | |
97e1c18e MD |
254 | |
255 | mutex_lock(&tracepoints_mutex); | |
de7b2973 MD |
256 | tp_func.func = probe; |
257 | tp_func.data = data; | |
258 | ret = tracepoint_add_func(tp, &tp_func); | |
b75ef8b4 | 259 | mutex_unlock(&tracepoints_mutex); |
b196e2b9 | 260 | return ret; |
97e1c18e MD |
261 | } |
262 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); | |
263 | ||
264 | /** | |
265 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint | |
de7b2973 | 266 | * @tp: tracepoint |
97e1c18e | 267 | * @probe: probe function pointer |
cac92ba7 | 268 | * @data: tracepoint data |
97e1c18e | 269 | * |
de7b2973 | 270 | * Returns 0 if ok, error value on error. |
97e1c18e | 271 | */ |
de7b2973 | 272 | int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data) |
97e1c18e | 273 | { |
de7b2973 MD |
274 | struct tracepoint_func tp_func; |
275 | int ret; | |
97e1c18e MD |
276 | |
277 | mutex_lock(&tracepoints_mutex); | |
de7b2973 MD |
278 | tp_func.func = probe; |
279 | tp_func.data = data; | |
280 | ret = tracepoint_remove_func(tp, &tp_func); | |
b75ef8b4 | 281 | mutex_unlock(&tracepoints_mutex); |
de7b2973 | 282 | return ret; |
97e1c18e MD |
283 | } |
284 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); | |
285 | ||
227a8375 | 286 | #ifdef CONFIG_MODULES |
45ab2813 SRRH |
287 | bool trace_module_has_bad_taint(struct module *mod) |
288 | { | |
66cc69e3 MD |
289 | return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) | |
290 | (1 << TAINT_UNSIGNED_MODULE)); | |
45ab2813 SRRH |
291 | } |
292 | ||
de7b2973 MD |
293 | static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list); |
294 | ||
295 | /** | |
296 | * register_tracepoint_notifier - register tracepoint coming/going notifier | |
297 | * @nb: notifier block | |
298 | * | |
299 | * Notifiers registered with this function are called on module | |
300 | * coming/going with the tracepoint_module_list_mutex held. | |
301 | * The notifier block callback should expect a "struct tp_module" data | |
302 | * pointer. | |
303 | */ | |
304 | int register_tracepoint_module_notifier(struct notifier_block *nb) | |
305 | { | |
306 | struct tp_module *tp_mod; | |
307 | int ret; | |
308 | ||
309 | mutex_lock(&tracepoint_module_list_mutex); | |
310 | ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb); | |
311 | if (ret) | |
312 | goto end; | |
313 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) | |
314 | (void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod); | |
315 | end: | |
316 | mutex_unlock(&tracepoint_module_list_mutex); | |
317 | return ret; | |
318 | } | |
319 | EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier); | |
320 | ||
321 | /** | |
322 | * unregister_tracepoint_notifier - unregister tracepoint coming/going notifier | |
323 | * @nb: notifier block | |
324 | * | |
325 | * The notifier block callback should expect a "struct tp_module" data | |
326 | * pointer. | |
327 | */ | |
328 | int unregister_tracepoint_module_notifier(struct notifier_block *nb) | |
329 | { | |
330 | struct tp_module *tp_mod; | |
331 | int ret; | |
332 | ||
333 | mutex_lock(&tracepoint_module_list_mutex); | |
334 | ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb); | |
335 | if (ret) | |
336 | goto end; | |
337 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) | |
338 | (void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod); | |
339 | end: | |
340 | mutex_unlock(&tracepoint_module_list_mutex); | |
341 | return ret; | |
342 | ||
343 | } | |
344 | EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier); | |
345 | ||
346 | /* | |
347 | * Ensure the tracer unregistered the module's probes before the module | |
348 | * teardown is performed. Prevents leaks of probe and data pointers. | |
349 | */ | |
350 | static void tp_module_going_check_quiescent(struct tracepoint * const *begin, | |
351 | struct tracepoint * const *end) | |
352 | { | |
353 | struct tracepoint * const *iter; | |
354 | ||
355 | if (!begin) | |
356 | return; | |
357 | for (iter = begin; iter < end; iter++) | |
358 | WARN_ON_ONCE((*iter)->funcs); | |
359 | } | |
360 | ||
b75ef8b4 MD |
361 | static int tracepoint_module_coming(struct module *mod) |
362 | { | |
0dea6d52 | 363 | struct tp_module *tp_mod; |
b75ef8b4 MD |
364 | int ret = 0; |
365 | ||
7dec935a SRRH |
366 | if (!mod->num_tracepoints) |
367 | return 0; | |
368 | ||
b75ef8b4 | 369 | /* |
c10076c4 SR |
370 | * We skip modules that taint the kernel, especially those with different |
371 | * module headers (for forced load), to make sure we don't cause a crash. | |
66cc69e3 | 372 | * Staging, out-of-tree, and unsigned GPL modules are fine. |
b75ef8b4 | 373 | */ |
45ab2813 | 374 | if (trace_module_has_bad_taint(mod)) |
b75ef8b4 | 375 | return 0; |
de7b2973 | 376 | mutex_lock(&tracepoint_module_list_mutex); |
b75ef8b4 MD |
377 | tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); |
378 | if (!tp_mod) { | |
379 | ret = -ENOMEM; | |
380 | goto end; | |
381 | } | |
eb7d035c | 382 | tp_mod->mod = mod; |
0dea6d52 | 383 | list_add_tail(&tp_mod->list, &tracepoint_module_list); |
de7b2973 MD |
384 | blocking_notifier_call_chain(&tracepoint_notify_list, |
385 | MODULE_STATE_COMING, tp_mod); | |
b75ef8b4 | 386 | end: |
de7b2973 | 387 | mutex_unlock(&tracepoint_module_list_mutex); |
b75ef8b4 MD |
388 | return ret; |
389 | } | |
390 | ||
de7b2973 | 391 | static void tracepoint_module_going(struct module *mod) |
b75ef8b4 | 392 | { |
de7b2973 | 393 | struct tp_module *tp_mod; |
b75ef8b4 | 394 | |
7dec935a | 395 | if (!mod->num_tracepoints) |
de7b2973 | 396 | return; |
7dec935a | 397 | |
de7b2973 MD |
398 | mutex_lock(&tracepoint_module_list_mutex); |
399 | list_for_each_entry(tp_mod, &tracepoint_module_list, list) { | |
eb7d035c | 400 | if (tp_mod->mod == mod) { |
de7b2973 MD |
401 | blocking_notifier_call_chain(&tracepoint_notify_list, |
402 | MODULE_STATE_GOING, tp_mod); | |
403 | list_del(&tp_mod->list); | |
404 | kfree(tp_mod); | |
405 | /* | |
406 | * Called the going notifier before checking for | |
407 | * quiescence. | |
408 | */ | |
409 | tp_module_going_check_quiescent(mod->tracepoints_ptrs, | |
410 | mod->tracepoints_ptrs + mod->num_tracepoints); | |
b75ef8b4 MD |
411 | break; |
412 | } | |
413 | } | |
414 | /* | |
415 | * In the case of modules that were tainted at "coming", we'll simply | |
416 | * walk through the list without finding it. We cannot use the "tainted" | |
417 | * flag on "going", in case a module taints the kernel only after being | |
418 | * loaded. | |
419 | */ | |
de7b2973 | 420 | mutex_unlock(&tracepoint_module_list_mutex); |
b75ef8b4 | 421 | } |
227a8375 | 422 | |
de7b2973 MD |
423 | static int tracepoint_module_notify(struct notifier_block *self, |
424 | unsigned long val, void *data) | |
32f85742 MD |
425 | { |
426 | struct module *mod = data; | |
b75ef8b4 | 427 | int ret = 0; |
32f85742 MD |
428 | |
429 | switch (val) { | |
430 | case MODULE_STATE_COMING: | |
b75ef8b4 MD |
431 | ret = tracepoint_module_coming(mod); |
432 | break; | |
433 | case MODULE_STATE_LIVE: | |
434 | break; | |
32f85742 | 435 | case MODULE_STATE_GOING: |
de7b2973 MD |
436 | tracepoint_module_going(mod); |
437 | break; | |
438 | case MODULE_STATE_UNFORMED: | |
32f85742 MD |
439 | break; |
440 | } | |
b75ef8b4 | 441 | return ret; |
32f85742 MD |
442 | } |
443 | ||
de7b2973 | 444 | static struct notifier_block tracepoint_module_nb = { |
32f85742 MD |
445 | .notifier_call = tracepoint_module_notify, |
446 | .priority = 0, | |
447 | }; | |
448 | ||
de7b2973 | 449 | static __init int init_tracepoints(void) |
32f85742 | 450 | { |
de7b2973 MD |
451 | int ret; |
452 | ||
453 | ret = register_module_notifier(&tracepoint_module_nb); | |
eb7d035c | 454 | if (ret) |
de7b2973 | 455 | pr_warning("Failed to register tracepoint module enter notifier\n"); |
eb7d035c | 456 | |
de7b2973 | 457 | return ret; |
32f85742 MD |
458 | } |
459 | __initcall(init_tracepoints); | |
227a8375 | 460 | #endif /* CONFIG_MODULES */ |
a871bd33 | 461 | |
de7b2973 MD |
462 | static void for_each_tracepoint_range(struct tracepoint * const *begin, |
463 | struct tracepoint * const *end, | |
464 | void (*fct)(struct tracepoint *tp, void *priv), | |
465 | void *priv) | |
466 | { | |
467 | struct tracepoint * const *iter; | |
468 | ||
469 | if (!begin) | |
470 | return; | |
471 | for (iter = begin; iter < end; iter++) | |
472 | fct(*iter, priv); | |
473 | } | |
474 | ||
475 | /** | |
476 | * for_each_kernel_tracepoint - iteration on all kernel tracepoints | |
477 | * @fct: callback | |
478 | * @priv: private data | |
479 | */ | |
480 | void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv), | |
481 | void *priv) | |
482 | { | |
483 | for_each_tracepoint_range(__start___tracepoints_ptrs, | |
484 | __stop___tracepoints_ptrs, fct, priv); | |
485 | } | |
486 | EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint); | |
487 | ||
3d27d8cb | 488 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
60d970c2 | 489 | |
97419875 | 490 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
a871bd33 JB |
491 | static int sys_tracepoint_refcount; |
492 | ||
493 | void syscall_regfunc(void) | |
494 | { | |
495 | unsigned long flags; | |
496 | struct task_struct *g, *t; | |
497 | ||
a871bd33 JB |
498 | if (!sys_tracepoint_refcount) { |
499 | read_lock_irqsave(&tasklist_lock, flags); | |
500 | do_each_thread(g, t) { | |
cc3b13c1 HB |
501 | /* Skip kernel threads. */ |
502 | if (t->mm) | |
503 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); | |
a871bd33 JB |
504 | } while_each_thread(g, t); |
505 | read_unlock_irqrestore(&tasklist_lock, flags); | |
506 | } | |
507 | sys_tracepoint_refcount++; | |
a871bd33 JB |
508 | } |
509 | ||
510 | void syscall_unregfunc(void) | |
511 | { | |
512 | unsigned long flags; | |
513 | struct task_struct *g, *t; | |
514 | ||
a871bd33 JB |
515 | sys_tracepoint_refcount--; |
516 | if (!sys_tracepoint_refcount) { | |
517 | read_lock_irqsave(&tasklist_lock, flags); | |
518 | do_each_thread(g, t) { | |
66700001 | 519 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); |
a871bd33 JB |
520 | } while_each_thread(g, t); |
521 | read_unlock_irqrestore(&tasklist_lock, flags); | |
522 | } | |
a871bd33 | 523 | } |
60d970c2 | 524 | #endif |