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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
30extern struct tracepoint * const __start___tracepoints_ptrs[];
31extern struct tracepoint * const __stop___tracepoints_ptrs[];
32
33
34static const int tracepoint_debug;
35
36#ifdef CONFIG_MODULES
37
38
39
40static DEFINE_MUTEX(tracepoint_module_list_mutex);
41
42
43static LIST_HEAD(tracepoint_module_list);
44#endif
45
46
47
48
49
50static DEFINE_MUTEX(tracepoints_mutex);
51
52
53
54
55
56
57struct tp_probes {
58 struct rcu_head rcu;
59 struct tracepoint_func probes[0];
60};
61
62static inline void *allocate_probes(int count)
63{
64 struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func)
65 + sizeof(struct tp_probes), GFP_KERNEL);
66 return p == NULL ? NULL : p->probes;
67}
68
69static void rcu_free_old_probes(struct rcu_head *head)
70{
71 kfree(container_of(head, struct tp_probes, rcu));
72}
73
74static inline void release_probes(struct tracepoint_func *old)
75{
76 if (old) {
77 struct tp_probes *tp_probes = container_of(old,
78 struct tp_probes, probes[0]);
79 call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
80 }
81}
82
83static void debug_print_probes(struct tracepoint_func *funcs)
84{
85 int i;
86
87 if (!tracepoint_debug || !funcs)
88 return;
89
90 for (i = 0; funcs[i].func; i++)
91 printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func);
92}
93
94static struct tracepoint_func *func_add(struct tracepoint_func **funcs,
95 struct tracepoint_func *tp_func)
96{
97 int nr_probes = 0;
98 struct tracepoint_func *old, *new;
99
100 if (WARN_ON(!tp_func->func))
101 return ERR_PTR(-EINVAL);
102
103 debug_print_probes(*funcs);
104 old = *funcs;
105 if (old) {
106
107 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
108 if (old[nr_probes].func == tp_func->func &&
109 old[nr_probes].data == tp_func->data)
110 return ERR_PTR(-EEXIST);
111 }
112
113 new = allocate_probes(nr_probes + 2);
114 if (new == NULL)
115 return ERR_PTR(-ENOMEM);
116 if (old)
117 memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
118 new[nr_probes] = *tp_func;
119 new[nr_probes + 1].func = NULL;
120 *funcs = new;
121 debug_print_probes(*funcs);
122 return old;
123}
124
125static void *func_remove(struct tracepoint_func **funcs,
126 struct tracepoint_func *tp_func)
127{
128 int nr_probes = 0, nr_del = 0, i;
129 struct tracepoint_func *old, *new;
130
131 old = *funcs;
132
133 if (!old)
134 return ERR_PTR(-ENOENT);
135
136 debug_print_probes(*funcs);
137
138 if (tp_func->func) {
139 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
140 if (old[nr_probes].func == tp_func->func &&
141 old[nr_probes].data == tp_func->data)
142 nr_del++;
143 }
144 }
145
146
147
148
149
150 if (nr_probes - nr_del == 0) {
151
152 *funcs = NULL;
153 debug_print_probes(*funcs);
154 return old;
155 } else {
156 int j = 0;
157
158
159 new = allocate_probes(nr_probes - nr_del + 1);
160 if (new == NULL)
161 return ERR_PTR(-ENOMEM);
162 for (i = 0; old[i].func; i++)
163 if (old[i].func != tp_func->func
164 || old[i].data != tp_func->data)
165 new[j++] = old[i];
166 new[nr_probes - nr_del].func = NULL;
167 *funcs = new;
168 }
169 debug_print_probes(*funcs);
170 return old;
171}
172
173
174
175
176static int tracepoint_add_func(struct tracepoint *tp,
177 struct tracepoint_func *func)
178{
179 struct tracepoint_func *old, *tp_funcs;
180
181 if (tp->regfunc && !static_key_enabled(&tp->key))
182 tp->regfunc();
183
184 tp_funcs = rcu_dereference_protected(tp->funcs,
185 lockdep_is_held(&tracepoints_mutex));
186 old = func_add(&tp_funcs, func);
187 if (IS_ERR(old)) {
188 WARN_ON_ONCE(1);
189 return PTR_ERR(old);
190 }
191
192
193
194
195
196
197
198
199 rcu_assign_pointer(tp->funcs, tp_funcs);
200 if (!static_key_enabled(&tp->key))
201 static_key_slow_inc(&tp->key);
202 release_probes(old);
203 return 0;
204}
205
206
207
208
209
210
211
212static int tracepoint_remove_func(struct tracepoint *tp,
213 struct tracepoint_func *func)
214{
215 struct tracepoint_func *old, *tp_funcs;
216
217 tp_funcs = rcu_dereference_protected(tp->funcs,
218 lockdep_is_held(&tracepoints_mutex));
219 old = func_remove(&tp_funcs, func);
220 if (IS_ERR(old)) {
221 WARN_ON_ONCE(1);
222 return PTR_ERR(old);
223 }
224
225 if (!tp_funcs) {
226
227 if (tp->unregfunc && static_key_enabled(&tp->key))
228 tp->unregfunc();
229
230 if (static_key_enabled(&tp->key))
231 static_key_slow_dec(&tp->key);
232 }
233 rcu_assign_pointer(tp->funcs, tp_funcs);
234 release_probes(old);
235 return 0;
236}
237
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244
245
246
247
248
249
250int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
251{
252 struct tracepoint_func tp_func;
253 int ret;
254
255 mutex_lock(&tracepoints_mutex);
256 tp_func.func = probe;
257 tp_func.data = data;
258 ret = tracepoint_add_func(tp, &tp_func);
259 mutex_unlock(&tracepoints_mutex);
260 return ret;
261}
262EXPORT_SYMBOL_GPL(tracepoint_probe_register);
263
264
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266
267
268
269
270
271
272int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
273{
274 struct tracepoint_func tp_func;
275 int ret;
276
277 mutex_lock(&tracepoints_mutex);
278 tp_func.func = probe;
279 tp_func.data = data;
280 ret = tracepoint_remove_func(tp, &tp_func);
281 mutex_unlock(&tracepoints_mutex);
282 return ret;
283}
284EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
285
286#ifdef CONFIG_MODULES
287bool trace_module_has_bad_taint(struct module *mod)
288{
289 return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
290 (1 << TAINT_UNSIGNED_MODULE));
291}
292
293static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
294
295
296
297
298
299
300
301
302
303
304int 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);
315end:
316 mutex_unlock(&tracepoint_module_list_mutex);
317 return ret;
318}
319EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);
320
321
322
323
324
325
326
327
328int 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);
339end:
340 mutex_unlock(&tracepoint_module_list_mutex);
341 return ret;
342
343}
344EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
345
346
347
348
349
350static 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
361static int tracepoint_module_coming(struct module *mod)
362{
363 struct tp_module *tp_mod;
364 int ret = 0;
365
366 if (!mod->num_tracepoints)
367 return 0;
368
369
370
371
372
373
374 if (trace_module_has_bad_taint(mod))
375 return 0;
376 mutex_lock(&tracepoint_module_list_mutex);
377 tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
378 if (!tp_mod) {
379 ret = -ENOMEM;
380 goto end;
381 }
382 tp_mod->mod = mod;
383 list_add_tail(&tp_mod->list, &tracepoint_module_list);
384 blocking_notifier_call_chain(&tracepoint_notify_list,
385 MODULE_STATE_COMING, tp_mod);
386end:
387 mutex_unlock(&tracepoint_module_list_mutex);
388 return ret;
389}
390
391static void tracepoint_module_going(struct module *mod)
392{
393 struct tp_module *tp_mod;
394
395 if (!mod->num_tracepoints)
396 return;
397
398 mutex_lock(&tracepoint_module_list_mutex);
399 list_for_each_entry(tp_mod, &tracepoint_module_list, list) {
400 if (tp_mod->mod == mod) {
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
407
408
409 tp_module_going_check_quiescent(mod->tracepoints_ptrs,
410 mod->tracepoints_ptrs + mod->num_tracepoints);
411 break;
412 }
413 }
414
415
416
417
418
419
420 mutex_unlock(&tracepoint_module_list_mutex);
421}
422
423static int tracepoint_module_notify(struct notifier_block *self,
424 unsigned long val, void *data)
425{
426 struct module *mod = data;
427 int ret = 0;
428
429 switch (val) {
430 case MODULE_STATE_COMING:
431 ret = tracepoint_module_coming(mod);
432 break;
433 case MODULE_STATE_LIVE:
434 break;
435 case MODULE_STATE_GOING:
436 tracepoint_module_going(mod);
437 break;
438 case MODULE_STATE_UNFORMED:
439 break;
440 }
441 return ret;
442}
443
444static struct notifier_block tracepoint_module_nb = {
445 .notifier_call = tracepoint_module_notify,
446 .priority = 0,
447};
448
449static __init int init_tracepoints(void)
450{
451 int ret;
452
453 ret = register_module_notifier(&tracepoint_module_nb);
454 if (ret)
455 pr_warning("Failed to register tracepoint module enter notifier\n");
456
457 return ret;
458}
459__initcall(init_tracepoints);
460#endif
461
462static 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
477
478
479
480void 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}
486EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
487
488#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
489
490
491static int sys_tracepoint_refcount;
492
493void syscall_regfunc(void)
494{
495 struct task_struct *p, *t;
496
497 if (!sys_tracepoint_refcount) {
498 read_lock(&tasklist_lock);
499 for_each_process_thread(p, t) {
500 set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
501 }
502 read_unlock(&tasklist_lock);
503 }
504 sys_tracepoint_refcount++;
505}
506
507void syscall_unregfunc(void)
508{
509 struct task_struct *p, *t;
510
511 sys_tracepoint_refcount--;
512 if (!sys_tracepoint_refcount) {
513 read_lock(&tasklist_lock);
514 for_each_process_thread(p, t) {
515 clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
516 }
517 read_unlock(&tasklist_lock);
518 }
519}
520#endif
521