1 #include <trace/syscall.h>
2 #include <trace/events/syscalls.h>
3 #include <linux/slab.h>
4 #include <linux/kernel.h>
5 #include <linux/ftrace.h>
6 #include <linux/perf_event.h>
7 #include <asm/syscall.h>
8
9 #include "trace_output.h"
10 #include "trace.h"
11
12 static DEFINE_MUTEX(syscall_trace_lock);
13 static int sys_refcount_enter;
14 static int sys_refcount_exit;
15 static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
16 static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
17
18 static int syscall_enter_register(struct ftrace_event_call *event,
19 enum trace_reg type);
20 static int syscall_exit_register(struct ftrace_event_call *event,
21 enum trace_reg type);
22
23 static int syscall_enter_define_fields(struct ftrace_event_call *call);
24 static int syscall_exit_define_fields(struct ftrace_event_call *call);
25
26 static struct list_head *
syscall_get_enter_fields(struct ftrace_event_call * call)27 syscall_get_enter_fields(struct ftrace_event_call *call)
28 {
29 struct syscall_metadata *entry = call->data;
30
31 return &entry->enter_fields;
32 }
33
34 struct trace_event_functions enter_syscall_print_funcs = {
35 .trace = print_syscall_enter,
36 };
37
38 struct trace_event_functions exit_syscall_print_funcs = {
39 .trace = print_syscall_exit,
40 };
41
42 struct ftrace_event_class event_class_syscall_enter = {
43 .system = "syscalls",
44 .reg = syscall_enter_register,
45 .define_fields = syscall_enter_define_fields,
46 .get_fields = syscall_get_enter_fields,
47 .raw_init = init_syscall_trace,
48 };
49
50 struct ftrace_event_class event_class_syscall_exit = {
51 .system = "syscalls",
52 .reg = syscall_exit_register,
53 .define_fields = syscall_exit_define_fields,
54 .fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
55 .raw_init = init_syscall_trace,
56 };
57
58 extern struct syscall_metadata *__start_syscalls_metadata[];
59 extern struct syscall_metadata *__stop_syscalls_metadata[];
60
61 static struct syscall_metadata **syscalls_metadata;
62
63 #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
arch_syscall_match_sym_name(const char * sym,const char * name)64 static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
65 {
66 /*
67 * Only compare after the "sys" prefix. Archs that use
68 * syscall wrappers may have syscalls symbols aliases prefixed
69 * with "SyS" instead of "sys", leading to an unwanted
70 * mismatch.
71 */
72 return !strcmp(sym + 3, name + 3);
73 }
74 #endif
75
76 static __init struct syscall_metadata *
find_syscall_meta(unsigned long syscall)77 find_syscall_meta(unsigned long syscall)
78 {
79 struct syscall_metadata **start;
80 struct syscall_metadata **stop;
81 char str[KSYM_SYMBOL_LEN];
82
83
84 start = __start_syscalls_metadata;
85 stop = __stop_syscalls_metadata;
86 kallsyms_lookup(syscall, NULL, NULL, NULL, str);
87
88 if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
89 return NULL;
90
91 for ( ; start < stop; start++) {
92 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
93 return *start;
94 }
95 return NULL;
96 }
97
syscall_nr_to_meta(int nr)98 static struct syscall_metadata *syscall_nr_to_meta(int nr)
99 {
100 if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
101 return NULL;
102
103 return syscalls_metadata[nr];
104 }
105
106 enum print_line_t
print_syscall_enter(struct trace_iterator * iter,int flags,struct trace_event * event)107 print_syscall_enter(struct trace_iterator *iter, int flags,
108 struct trace_event *event)
109 {
110 struct trace_seq *s = &iter->seq;
111 struct trace_entry *ent = iter->ent;
112 struct syscall_trace_enter *trace;
113 struct syscall_metadata *entry;
114 int i, ret, syscall;
115
116 trace = (typeof(trace))ent;
117 syscall = trace->nr;
118 entry = syscall_nr_to_meta(syscall);
119
120 if (!entry)
121 goto end;
122
123 if (entry->enter_event->event.type != ent->type) {
124 WARN_ON_ONCE(1);
125 goto end;
126 }
127
128 ret = trace_seq_printf(s, "%s(", entry->name);
129 if (!ret)
130 return TRACE_TYPE_PARTIAL_LINE;
131
132 for (i = 0; i < entry->nb_args; i++) {
133 /* parameter types */
134 if (trace_flags & TRACE_ITER_VERBOSE) {
135 ret = trace_seq_printf(s, "%s ", entry->types[i]);
136 if (!ret)
137 return TRACE_TYPE_PARTIAL_LINE;
138 }
139 /* parameter values */
140 ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
141 trace->args[i],
142 i == entry->nb_args - 1 ? "" : ", ");
143 if (!ret)
144 return TRACE_TYPE_PARTIAL_LINE;
145 }
146
147 ret = trace_seq_putc(s, ')');
148 if (!ret)
149 return TRACE_TYPE_PARTIAL_LINE;
150
151 end:
152 ret = trace_seq_putc(s, '\n');
153 if (!ret)
154 return TRACE_TYPE_PARTIAL_LINE;
155
156 return TRACE_TYPE_HANDLED;
157 }
158
159 enum print_line_t
print_syscall_exit(struct trace_iterator * iter,int flags,struct trace_event * event)160 print_syscall_exit(struct trace_iterator *iter, int flags,
161 struct trace_event *event)
162 {
163 struct trace_seq *s = &iter->seq;
164 struct trace_entry *ent = iter->ent;
165 struct syscall_trace_exit *trace;
166 int syscall;
167 struct syscall_metadata *entry;
168 int ret;
169
170 trace = (typeof(trace))ent;
171 syscall = trace->nr;
172 entry = syscall_nr_to_meta(syscall);
173
174 if (!entry) {
175 trace_seq_printf(s, "\n");
176 return TRACE_TYPE_HANDLED;
177 }
178
179 if (entry->exit_event->event.type != ent->type) {
180 WARN_ON_ONCE(1);
181 return TRACE_TYPE_UNHANDLED;
182 }
183
184 ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
185 trace->ret);
186 if (!ret)
187 return TRACE_TYPE_PARTIAL_LINE;
188
189 return TRACE_TYPE_HANDLED;
190 }
191
192 extern char *__bad_type_size(void);
193
194 #define SYSCALL_FIELD(type, name) \
195 sizeof(type) != sizeof(trace.name) ? \
196 __bad_type_size() : \
197 #type, #name, offsetof(typeof(trace), name), \
198 sizeof(trace.name), is_signed_type(type)
199
200 static
__set_enter_print_fmt(struct syscall_metadata * entry,char * buf,int len)201 int __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
202 {
203 int i;
204 int pos = 0;
205
206 /* When len=0, we just calculate the needed length */
207 #define LEN_OR_ZERO (len ? len - pos : 0)
208
209 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
210 for (i = 0; i < entry->nb_args; i++) {
211 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
212 entry->args[i], sizeof(unsigned long),
213 i == entry->nb_args - 1 ? "" : ", ");
214 }
215 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
216
217 for (i = 0; i < entry->nb_args; i++) {
218 pos += snprintf(buf + pos, LEN_OR_ZERO,
219 ", ((unsigned long)(REC->%s))", entry->args[i]);
220 }
221
222 #undef LEN_OR_ZERO
223
224 /* return the length of print_fmt */
225 return pos;
226 }
227
set_syscall_print_fmt(struct ftrace_event_call * call)228 static int set_syscall_print_fmt(struct ftrace_event_call *call)
229 {
230 char *print_fmt;
231 int len;
232 struct syscall_metadata *entry = call->data;
233
234 if (entry->enter_event != call) {
235 call->print_fmt = "\"0x%lx\", REC->ret";
236 return 0;
237 }
238
239 /* First: called with 0 length to calculate the needed length */
240 len = __set_enter_print_fmt(entry, NULL, 0);
241
242 print_fmt = kmalloc(len + 1, GFP_KERNEL);
243 if (!print_fmt)
244 return -ENOMEM;
245
246 /* Second: actually write the @print_fmt */
247 __set_enter_print_fmt(entry, print_fmt, len + 1);
248 call->print_fmt = print_fmt;
249
250 return 0;
251 }
252
free_syscall_print_fmt(struct ftrace_event_call * call)253 static void free_syscall_print_fmt(struct ftrace_event_call *call)
254 {
255 struct syscall_metadata *entry = call->data;
256
257 if (entry->enter_event == call)
258 kfree(call->print_fmt);
259 }
260
syscall_enter_define_fields(struct ftrace_event_call * call)261 static int syscall_enter_define_fields(struct ftrace_event_call *call)
262 {
263 struct syscall_trace_enter trace;
264 struct syscall_metadata *meta = call->data;
265 int ret;
266 int i;
267 int offset = offsetof(typeof(trace), args);
268
269 ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
270 if (ret)
271 return ret;
272
273 for (i = 0; i < meta->nb_args; i++) {
274 ret = trace_define_field(call, meta->types[i],
275 meta->args[i], offset,
276 sizeof(unsigned long), 0,
277 FILTER_OTHER);
278 offset += sizeof(unsigned long);
279 }
280
281 return ret;
282 }
283
syscall_exit_define_fields(struct ftrace_event_call * call)284 static int syscall_exit_define_fields(struct ftrace_event_call *call)
285 {
286 struct syscall_trace_exit trace;
287 int ret;
288
289 ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
290 if (ret)
291 return ret;
292
293 ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
294 FILTER_OTHER);
295
296 return ret;
297 }
298
ftrace_syscall_enter(void * ignore,struct pt_regs * regs,long id)299 void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
300 {
301 struct syscall_trace_enter *entry;
302 struct syscall_metadata *sys_data;
303 struct ring_buffer_event *event;
304 struct ring_buffer *buffer;
305 int size;
306 int syscall_nr;
307
308 syscall_nr = syscall_get_nr(current, regs);
309 if (syscall_nr < 0)
310 return;
311 if (!test_bit(syscall_nr, enabled_enter_syscalls))
312 return;
313
314 sys_data = syscall_nr_to_meta(syscall_nr);
315 if (!sys_data)
316 return;
317
318 size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
319
320 event = trace_current_buffer_lock_reserve(&buffer,
321 sys_data->enter_event->event.type, size, 0, 0);
322 if (!event)
323 return;
324
325 entry = ring_buffer_event_data(event);
326 entry->nr = syscall_nr;
327 syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
328
329 if (!filter_current_check_discard(buffer, sys_data->enter_event,
330 entry, event))
331 trace_current_buffer_unlock_commit(buffer, event, 0, 0);
332 }
333
ftrace_syscall_exit(void * ignore,struct pt_regs * regs,long ret)334 void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
335 {
336 struct syscall_trace_exit *entry;
337 struct syscall_metadata *sys_data;
338 struct ring_buffer_event *event;
339 struct ring_buffer *buffer;
340 int syscall_nr;
341
342 syscall_nr = syscall_get_nr(current, regs);
343 if (syscall_nr < 0)
344 return;
345 if (!test_bit(syscall_nr, enabled_exit_syscalls))
346 return;
347
348 sys_data = syscall_nr_to_meta(syscall_nr);
349 if (!sys_data)
350 return;
351
352 event = trace_current_buffer_lock_reserve(&buffer,
353 sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
354 if (!event)
355 return;
356
357 entry = ring_buffer_event_data(event);
358 entry->nr = syscall_nr;
359 entry->ret = syscall_get_return_value(current, regs);
360
361 if (!filter_current_check_discard(buffer, sys_data->exit_event,
362 entry, event))
363 trace_current_buffer_unlock_commit(buffer, event, 0, 0);
364 }
365
reg_event_syscall_enter(struct ftrace_event_call * call)366 int reg_event_syscall_enter(struct ftrace_event_call *call)
367 {
368 int ret = 0;
369 int num;
370
371 num = ((struct syscall_metadata *)call->data)->syscall_nr;
372 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
373 return -ENOSYS;
374 mutex_lock(&syscall_trace_lock);
375 if (!sys_refcount_enter)
376 ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
377 if (!ret) {
378 set_bit(num, enabled_enter_syscalls);
379 sys_refcount_enter++;
380 }
381 mutex_unlock(&syscall_trace_lock);
382 return ret;
383 }
384
unreg_event_syscall_enter(struct ftrace_event_call * call)385 void unreg_event_syscall_enter(struct ftrace_event_call *call)
386 {
387 int num;
388
389 num = ((struct syscall_metadata *)call->data)->syscall_nr;
390 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
391 return;
392 mutex_lock(&syscall_trace_lock);
393 sys_refcount_enter--;
394 clear_bit(num, enabled_enter_syscalls);
395 if (!sys_refcount_enter)
396 unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
397 mutex_unlock(&syscall_trace_lock);
398 }
399
reg_event_syscall_exit(struct ftrace_event_call * call)400 int reg_event_syscall_exit(struct ftrace_event_call *call)
401 {
402 int ret = 0;
403 int num;
404
405 num = ((struct syscall_metadata *)call->data)->syscall_nr;
406 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
407 return -ENOSYS;
408 mutex_lock(&syscall_trace_lock);
409 if (!sys_refcount_exit)
410 ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
411 if (!ret) {
412 set_bit(num, enabled_exit_syscalls);
413 sys_refcount_exit++;
414 }
415 mutex_unlock(&syscall_trace_lock);
416 return ret;
417 }
418
unreg_event_syscall_exit(struct ftrace_event_call * call)419 void unreg_event_syscall_exit(struct ftrace_event_call *call)
420 {
421 int num;
422
423 num = ((struct syscall_metadata *)call->data)->syscall_nr;
424 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
425 return;
426 mutex_lock(&syscall_trace_lock);
427 sys_refcount_exit--;
428 clear_bit(num, enabled_exit_syscalls);
429 if (!sys_refcount_exit)
430 unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
431 mutex_unlock(&syscall_trace_lock);
432 }
433
init_syscall_trace(struct ftrace_event_call * call)434 int init_syscall_trace(struct ftrace_event_call *call)
435 {
436 int id;
437 int num;
438
439 num = ((struct syscall_metadata *)call->data)->syscall_nr;
440 if (num < 0 || num >= NR_syscalls) {
441 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
442 ((struct syscall_metadata *)call->data)->name);
443 return -ENOSYS;
444 }
445
446 if (set_syscall_print_fmt(call) < 0)
447 return -ENOMEM;
448
449 id = trace_event_raw_init(call);
450
451 if (id < 0) {
452 free_syscall_print_fmt(call);
453 return id;
454 }
455
456 return id;
457 }
458
arch_syscall_addr(int nr)459 unsigned long __init __weak arch_syscall_addr(int nr)
460 {
461 return (unsigned long)sys_call_table[nr];
462 }
463
init_ftrace_syscalls(void)464 int __init init_ftrace_syscalls(void)
465 {
466 struct syscall_metadata *meta;
467 unsigned long addr;
468 int i;
469
470 syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
471 NR_syscalls, GFP_KERNEL);
472 if (!syscalls_metadata) {
473 WARN_ON(1);
474 return -ENOMEM;
475 }
476
477 for (i = 0; i < NR_syscalls; i++) {
478 addr = arch_syscall_addr(i);
479 meta = find_syscall_meta(addr);
480 if (!meta)
481 continue;
482
483 meta->syscall_nr = i;
484 syscalls_metadata[i] = meta;
485 }
486
487 return 0;
488 }
489 core_initcall(init_ftrace_syscalls);
490
491 #ifdef CONFIG_PERF_EVENTS
492
493 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
494 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
495 static int sys_perf_refcount_enter;
496 static int sys_perf_refcount_exit;
497
perf_syscall_enter(void * ignore,struct pt_regs * regs,long id)498 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
499 {
500 struct syscall_metadata *sys_data;
501 struct syscall_trace_enter *rec;
502 struct hlist_head *head;
503 int syscall_nr;
504 int rctx;
505 int size;
506
507 syscall_nr = syscall_get_nr(current, regs);
508 if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
509 return;
510
511 sys_data = syscall_nr_to_meta(syscall_nr);
512 if (!sys_data)
513 return;
514
515 /* get the size after alignment with the u32 buffer size field */
516 size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
517 size = ALIGN(size + sizeof(u32), sizeof(u64));
518 size -= sizeof(u32);
519
520 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
521 "perf buffer not large enough"))
522 return;
523
524 rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
525 sys_data->enter_event->event.type, regs, &rctx);
526 if (!rec)
527 return;
528
529 rec->nr = syscall_nr;
530 syscall_get_arguments(current, regs, 0, sys_data->nb_args,
531 (unsigned long *)&rec->args);
532
533 head = this_cpu_ptr(sys_data->enter_event->perf_events);
534 perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
535 }
536
perf_sysenter_enable(struct ftrace_event_call * call)537 int perf_sysenter_enable(struct ftrace_event_call *call)
538 {
539 int ret = 0;
540 int num;
541
542 num = ((struct syscall_metadata *)call->data)->syscall_nr;
543
544 mutex_lock(&syscall_trace_lock);
545 if (!sys_perf_refcount_enter)
546 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
547 if (ret) {
548 pr_info("event trace: Could not activate"
549 "syscall entry trace point");
550 } else {
551 set_bit(num, enabled_perf_enter_syscalls);
552 sys_perf_refcount_enter++;
553 }
554 mutex_unlock(&syscall_trace_lock);
555 return ret;
556 }
557
perf_sysenter_disable(struct ftrace_event_call * call)558 void perf_sysenter_disable(struct ftrace_event_call *call)
559 {
560 int num;
561
562 num = ((struct syscall_metadata *)call->data)->syscall_nr;
563
564 mutex_lock(&syscall_trace_lock);
565 sys_perf_refcount_enter--;
566 clear_bit(num, enabled_perf_enter_syscalls);
567 if (!sys_perf_refcount_enter)
568 unregister_trace_sys_enter(perf_syscall_enter, NULL);
569 mutex_unlock(&syscall_trace_lock);
570 }
571
perf_syscall_exit(void * ignore,struct pt_regs * regs,long ret)572 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
573 {
574 struct syscall_metadata *sys_data;
575 struct syscall_trace_exit *rec;
576 struct hlist_head *head;
577 int syscall_nr;
578 int rctx;
579 int size;
580
581 syscall_nr = syscall_get_nr(current, regs);
582 if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
583 return;
584
585 sys_data = syscall_nr_to_meta(syscall_nr);
586 if (!sys_data)
587 return;
588
589 /* We can probably do that at build time */
590 size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
591 size -= sizeof(u32);
592
593 /*
594 * Impossible, but be paranoid with the future
595 * How to put this check outside runtime?
596 */
597 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
598 "exit event has grown above perf buffer size"))
599 return;
600
601 rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
602 sys_data->exit_event->event.type, regs, &rctx);
603 if (!rec)
604 return;
605
606 rec->nr = syscall_nr;
607 rec->ret = syscall_get_return_value(current, regs);
608
609 head = this_cpu_ptr(sys_data->exit_event->perf_events);
610 perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
611 }
612
perf_sysexit_enable(struct ftrace_event_call * call)613 int perf_sysexit_enable(struct ftrace_event_call *call)
614 {
615 int ret = 0;
616 int num;
617
618 num = ((struct syscall_metadata *)call->data)->syscall_nr;
619
620 mutex_lock(&syscall_trace_lock);
621 if (!sys_perf_refcount_exit)
622 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
623 if (ret) {
624 pr_info("event trace: Could not activate"
625 "syscall exit trace point");
626 } else {
627 set_bit(num, enabled_perf_exit_syscalls);
628 sys_perf_refcount_exit++;
629 }
630 mutex_unlock(&syscall_trace_lock);
631 return ret;
632 }
633
perf_sysexit_disable(struct ftrace_event_call * call)634 void perf_sysexit_disable(struct ftrace_event_call *call)
635 {
636 int num;
637
638 num = ((struct syscall_metadata *)call->data)->syscall_nr;
639
640 mutex_lock(&syscall_trace_lock);
641 sys_perf_refcount_exit--;
642 clear_bit(num, enabled_perf_exit_syscalls);
643 if (!sys_perf_refcount_exit)
644 unregister_trace_sys_exit(perf_syscall_exit, NULL);
645 mutex_unlock(&syscall_trace_lock);
646 }
647
648 #endif /* CONFIG_PERF_EVENTS */
649
syscall_enter_register(struct ftrace_event_call * event,enum trace_reg type)650 static int syscall_enter_register(struct ftrace_event_call *event,
651 enum trace_reg type)
652 {
653 switch (type) {
654 case TRACE_REG_REGISTER:
655 return reg_event_syscall_enter(event);
656 case TRACE_REG_UNREGISTER:
657 unreg_event_syscall_enter(event);
658 return 0;
659
660 #ifdef CONFIG_PERF_EVENTS
661 case TRACE_REG_PERF_REGISTER:
662 return perf_sysenter_enable(event);
663 case TRACE_REG_PERF_UNREGISTER:
664 perf_sysenter_disable(event);
665 return 0;
666 #endif
667 }
668 return 0;
669 }
670
syscall_exit_register(struct ftrace_event_call * event,enum trace_reg type)671 static int syscall_exit_register(struct ftrace_event_call *event,
672 enum trace_reg type)
673 {
674 switch (type) {
675 case TRACE_REG_REGISTER:
676 return reg_event_syscall_exit(event);
677 case TRACE_REG_UNREGISTER:
678 unreg_event_syscall_exit(event);
679 return 0;
680
681 #ifdef CONFIG_PERF_EVENTS
682 case TRACE_REG_PERF_REGISTER:
683 return perf_sysexit_enable(event);
684 case TRACE_REG_PERF_UNREGISTER:
685 perf_sysexit_disable(event);
686 return 0;
687 #endif
688 }
689 return 0;
690 }
691