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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/jump_label.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
37
38
39
40static DEFINE_MUTEX(tracepoints_mutex);
41
42
43
44
45
46#define TRACEPOINT_HASH_BITS 6
47#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
48static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
49
50
51
52
53
54
55
56struct tracepoint_entry {
57 struct hlist_node hlist;
58 struct tracepoint_func *funcs;
59 int refcount;
60 char name[0];
61};
62
63struct tp_probes {
64 union {
65 struct rcu_head rcu;
66 struct list_head list;
67 } u;
68 struct tracepoint_func probes[0];
69};
70
71static inline void *allocate_probes(int count)
72{
73 struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func)
74 + sizeof(struct tp_probes), GFP_KERNEL);
75 return p == NULL ? NULL : p->probes;
76}
77
78static void rcu_free_old_probes(struct rcu_head *head)
79{
80 kfree(container_of(head, struct tp_probes, u.rcu));
81}
82
83static inline void release_probes(struct tracepoint_func *old)
84{
85 if (old) {
86 struct tp_probes *tp_probes = container_of(old,
87 struct tp_probes, probes[0]);
88 call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
89 }
90}
91
92static void debug_print_probes(struct tracepoint_entry *entry)
93{
94 int i;
95
96 if (!tracepoint_debug || !entry->funcs)
97 return;
98
99 for (i = 0; entry->funcs[i].func; i++)
100 printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func);
101}
102
103static struct tracepoint_func *
104tracepoint_entry_add_probe(struct tracepoint_entry *entry,
105 void *probe, void *data)
106{
107 int nr_probes = 0;
108 struct tracepoint_func *old, *new;
109
110 WARN_ON(!probe);
111
112 debug_print_probes(entry);
113 old = entry->funcs;
114 if (old) {
115
116 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
117 if (old[nr_probes].func == probe &&
118 old[nr_probes].data == data)
119 return ERR_PTR(-EEXIST);
120 }
121
122 new = allocate_probes(nr_probes + 2);
123 if (new == NULL)
124 return ERR_PTR(-ENOMEM);
125 if (old)
126 memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
127 new[nr_probes].func = probe;
128 new[nr_probes].data = data;
129 new[nr_probes + 1].func = NULL;
130 entry->refcount = nr_probes + 1;
131 entry->funcs = new;
132 debug_print_probes(entry);
133 return old;
134}
135
136static void *
137tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
138 void *probe, void *data)
139{
140 int nr_probes = 0, nr_del = 0, i;
141 struct tracepoint_func *old, *new;
142
143 old = entry->funcs;
144
145 if (!old)
146 return ERR_PTR(-ENOENT);
147
148 debug_print_probes(entry);
149
150 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
151 if (!probe ||
152 (old[nr_probes].func == probe &&
153 old[nr_probes].data == data))
154 nr_del++;
155 }
156
157 if (nr_probes - nr_del == 0) {
158
159 entry->funcs = NULL;
160 entry->refcount = 0;
161 debug_print_probes(entry);
162 return old;
163 } else {
164 int j = 0;
165
166
167 new = allocate_probes(nr_probes - nr_del + 1);
168 if (new == NULL)
169 return ERR_PTR(-ENOMEM);
170 for (i = 0; old[i].func; i++)
171 if (probe &&
172 (old[i].func != probe || old[i].data != data))
173 new[j++] = old[i];
174 new[nr_probes - nr_del].func = NULL;
175 entry->refcount = nr_probes - nr_del;
176 entry->funcs = new;
177 }
178 debug_print_probes(entry);
179 return old;
180}
181
182
183
184
185
186
187static struct tracepoint_entry *get_tracepoint(const char *name)
188{
189 struct hlist_head *head;
190 struct hlist_node *node;
191 struct tracepoint_entry *e;
192 u32 hash = jhash(name, strlen(name), 0);
193
194 head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
195 hlist_for_each_entry(e, node, head, hlist) {
196 if (!strcmp(name, e->name))
197 return e;
198 }
199 return NULL;
200}
201
202
203
204
205
206static struct tracepoint_entry *add_tracepoint(const char *name)
207{
208 struct hlist_head *head;
209 struct hlist_node *node;
210 struct tracepoint_entry *e;
211 size_t name_len = strlen(name) + 1;
212 u32 hash = jhash(name, name_len-1, 0);
213
214 head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
215 hlist_for_each_entry(e, node, head, hlist) {
216 if (!strcmp(name, e->name)) {
217 printk(KERN_NOTICE
218 "tracepoint %s busy\n", name);
219 return ERR_PTR(-EEXIST);
220 }
221 }
222
223
224
225
226 e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
227 if (!e)
228 return ERR_PTR(-ENOMEM);
229 memcpy(&e->name[0], name, name_len);
230 e->funcs = NULL;
231 e->refcount = 0;
232 hlist_add_head(&e->hlist, head);
233 return e;
234}
235
236
237
238
239
240static inline void remove_tracepoint(struct tracepoint_entry *e)
241{
242 hlist_del(&e->hlist);
243 kfree(e);
244}
245
246
247
248
249static void set_tracepoint(struct tracepoint_entry **entry,
250 struct tracepoint *elem, int active)
251{
252 WARN_ON(strcmp((*entry)->name, elem->name) != 0);
253
254 if (elem->regfunc && !elem->state && active)
255 elem->regfunc();
256 else if (elem->unregfunc && elem->state && !active)
257 elem->unregfunc();
258
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264
265
266 rcu_assign_pointer(elem->funcs, (*entry)->funcs);
267 if (!elem->state && active) {
268 jump_label_enable(&elem->state);
269 elem->state = active;
270 } else if (elem->state && !active) {
271 jump_label_disable(&elem->state);
272 elem->state = active;
273 }
274}
275
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280
281
282static void disable_tracepoint(struct tracepoint *elem)
283{
284 if (elem->unregfunc && elem->state)
285 elem->unregfunc();
286
287 if (elem->state) {
288 jump_label_disable(&elem->state);
289 elem->state = 0;
290 }
291 rcu_assign_pointer(elem->funcs, NULL);
292}
293
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298
299
300
301void tracepoint_update_probe_range(struct tracepoint * const *begin,
302 struct tracepoint * const *end)
303{
304 struct tracepoint * const *iter;
305 struct tracepoint_entry *mark_entry;
306
307 if (!begin)
308 return;
309
310 mutex_lock(&tracepoints_mutex);
311 for (iter = begin; iter < end; iter++) {
312 mark_entry = get_tracepoint((*iter)->name);
313 if (mark_entry) {
314 set_tracepoint(&mark_entry, *iter,
315 !!mark_entry->refcount);
316 } else {
317 disable_tracepoint(*iter);
318 }
319 }
320 mutex_unlock(&tracepoints_mutex);
321}
322
323
324
325
326static void tracepoint_update_probes(void)
327{
328
329 tracepoint_update_probe_range(__start___tracepoints_ptrs,
330 __stop___tracepoints_ptrs);
331
332 module_update_tracepoints();
333}
334
335static struct tracepoint_func *
336tracepoint_add_probe(const char *name, void *probe, void *data)
337{
338 struct tracepoint_entry *entry;
339 struct tracepoint_func *old;
340
341 entry = get_tracepoint(name);
342 if (!entry) {
343 entry = add_tracepoint(name);
344 if (IS_ERR(entry))
345 return (struct tracepoint_func *)entry;
346 }
347 old = tracepoint_entry_add_probe(entry, probe, data);
348 if (IS_ERR(old) && !entry->refcount)
349 remove_tracepoint(entry);
350 return old;
351}
352
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357
358
359
360
361int tracepoint_probe_register(const char *name, void *probe, void *data)
362{
363 struct tracepoint_func *old;
364
365 mutex_lock(&tracepoints_mutex);
366 old = tracepoint_add_probe(name, probe, data);
367 mutex_unlock(&tracepoints_mutex);
368 if (IS_ERR(old))
369 return PTR_ERR(old);
370
371 tracepoint_update_probes();
372 release_probes(old);
373 return 0;
374}
375EXPORT_SYMBOL_GPL(tracepoint_probe_register);
376
377static struct tracepoint_func *
378tracepoint_remove_probe(const char *name, void *probe, void *data)
379{
380 struct tracepoint_entry *entry;
381 struct tracepoint_func *old;
382
383 entry = get_tracepoint(name);
384 if (!entry)
385 return ERR_PTR(-ENOENT);
386 old = tracepoint_entry_remove_probe(entry, probe, data);
387 if (IS_ERR(old))
388 return old;
389 if (!entry->refcount)
390 remove_tracepoint(entry);
391 return old;
392}
393
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397
398
399
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401
402
403
404int tracepoint_probe_unregister(const char *name, void *probe, void *data)
405{
406 struct tracepoint_func *old;
407
408 mutex_lock(&tracepoints_mutex);
409 old = tracepoint_remove_probe(name, probe, data);
410 mutex_unlock(&tracepoints_mutex);
411 if (IS_ERR(old))
412 return PTR_ERR(old);
413
414 tracepoint_update_probes();
415 release_probes(old);
416 return 0;
417}
418EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
419
420static LIST_HEAD(old_probes);
421static int need_update;
422
423static void tracepoint_add_old_probes(void *old)
424{
425 need_update = 1;
426 if (old) {
427 struct tp_probes *tp_probes = container_of(old,
428 struct tp_probes, probes[0]);
429 list_add(&tp_probes->u.list, &old_probes);
430 }
431}
432
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434
435
436
437
438
439
440int tracepoint_probe_register_noupdate(const char *name, void *probe,
441 void *data)
442{
443 struct tracepoint_func *old;
444
445 mutex_lock(&tracepoints_mutex);
446 old = tracepoint_add_probe(name, probe, data);
447 if (IS_ERR(old)) {
448 mutex_unlock(&tracepoints_mutex);
449 return PTR_ERR(old);
450 }
451 tracepoint_add_old_probes(old);
452 mutex_unlock(&tracepoints_mutex);
453 return 0;
454}
455EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
456
457
458
459
460
461
462
463
464int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
465 void *data)
466{
467 struct tracepoint_func *old;
468
469 mutex_lock(&tracepoints_mutex);
470 old = tracepoint_remove_probe(name, probe, data);
471 if (IS_ERR(old)) {
472 mutex_unlock(&tracepoints_mutex);
473 return PTR_ERR(old);
474 }
475 tracepoint_add_old_probes(old);
476 mutex_unlock(&tracepoints_mutex);
477 return 0;
478}
479EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
480
481
482
483
484void tracepoint_probe_update_all(void)
485{
486 LIST_HEAD(release_probes);
487 struct tp_probes *pos, *next;
488
489 mutex_lock(&tracepoints_mutex);
490 if (!need_update) {
491 mutex_unlock(&tracepoints_mutex);
492 return;
493 }
494 if (!list_empty(&old_probes))
495 list_replace_init(&old_probes, &release_probes);
496 need_update = 0;
497 mutex_unlock(&tracepoints_mutex);
498
499 tracepoint_update_probes();
500 list_for_each_entry_safe(pos, next, &release_probes, u.list) {
501 list_del(&pos->u.list);
502 call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
503 }
504}
505EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
506
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509
510
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513
514
515
516
517int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
518 struct tracepoint * const *begin, struct tracepoint * const *end)
519{
520 if (!*tracepoint && begin != end) {
521 *tracepoint = begin;
522 return 1;
523 }
524 if (*tracepoint >= begin && *tracepoint < end)
525 return 1;
526 return 0;
527}
528EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);
529
530static void tracepoint_get_iter(struct tracepoint_iter *iter)
531{
532 int found = 0;
533
534
535 if (!iter->module) {
536 found = tracepoint_get_iter_range(&iter->tracepoint,
537 __start___tracepoints_ptrs,
538 __stop___tracepoints_ptrs);
539 if (found)
540 goto end;
541 }
542
543 found = module_get_iter_tracepoints(iter);
544end:
545 if (!found)
546 tracepoint_iter_reset(iter);
547}
548
549void tracepoint_iter_start(struct tracepoint_iter *iter)
550{
551 tracepoint_get_iter(iter);
552}
553EXPORT_SYMBOL_GPL(tracepoint_iter_start);
554
555void tracepoint_iter_next(struct tracepoint_iter *iter)
556{
557 iter->tracepoint++;
558
559
560
561
562
563 tracepoint_get_iter(iter);
564}
565EXPORT_SYMBOL_GPL(tracepoint_iter_next);
566
567void tracepoint_iter_stop(struct tracepoint_iter *iter)
568{
569}
570EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
571
572void tracepoint_iter_reset(struct tracepoint_iter *iter)
573{
574 iter->module = NULL;
575 iter->tracepoint = NULL;
576}
577EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
578
579#ifdef CONFIG_MODULES
580
581int tracepoint_module_notify(struct notifier_block *self,
582 unsigned long val, void *data)
583{
584 struct module *mod = data;
585
586 switch (val) {
587 case MODULE_STATE_COMING:
588 case MODULE_STATE_GOING:
589 tracepoint_update_probe_range(mod->tracepoints_ptrs,
590 mod->tracepoints_ptrs + mod->num_tracepoints);
591 break;
592 }
593 return 0;
594}
595
596struct notifier_block tracepoint_module_nb = {
597 .notifier_call = tracepoint_module_notify,
598 .priority = 0,
599};
600
601static int init_tracepoints(void)
602{
603 return register_module_notifier(&tracepoint_module_nb);
604}
605__initcall(init_tracepoints);
606
607#endif
608
609#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
610
611
612static int sys_tracepoint_refcount;
613
614void syscall_regfunc(void)
615{
616 unsigned long flags;
617 struct task_struct *g, *t;
618
619 if (!sys_tracepoint_refcount) {
620 read_lock_irqsave(&tasklist_lock, flags);
621 do_each_thread(g, t) {
622
623 if (t->mm)
624 set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
625 } while_each_thread(g, t);
626 read_unlock_irqrestore(&tasklist_lock, flags);
627 }
628 sys_tracepoint_refcount++;
629}
630
631void syscall_unregfunc(void)
632{
633 unsigned long flags;
634 struct task_struct *g, *t;
635
636 sys_tracepoint_refcount--;
637 if (!sys_tracepoint_refcount) {
638 read_lock_irqsave(&tasklist_lock, flags);
639 do_each_thread(g, t) {
640 clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
641 } while_each_thread(g, t);
642 read_unlock_irqrestore(&tasklist_lock, flags);
643 }
644}
645#endif
646