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TOMOYO Linux Cross Reference
Linux/kernel/trace/trace_events.c

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  1 /*
  2  * event tracer
  3  *
  4  * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
  5  *
  6  *  - Added format output of fields of the trace point.
  7  *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
  8  *
  9  */
 10 
 11 #include <linux/workqueue.h>
 12 #include <linux/spinlock.h>
 13 #include <linux/kthread.h>
 14 #include <linux/debugfs.h>
 15 #include <linux/uaccess.h>
 16 #include <linux/module.h>
 17 #include <linux/ctype.h>
 18 #include <linux/slab.h>
 19 #include <linux/delay.h>
 20 
 21 #include <asm/setup.h>
 22 
 23 #include "trace_output.h"
 24 
 25 #undef TRACE_SYSTEM
 26 #define TRACE_SYSTEM "TRACE_SYSTEM"
 27 
 28 DEFINE_MUTEX(event_mutex);
 29 
 30 LIST_HEAD(ftrace_events);
 31 static LIST_HEAD(ftrace_common_fields);
 32 
 33 #define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)
 34 
 35 static struct kmem_cache *field_cachep;
 36 static struct kmem_cache *file_cachep;
 37 
 38 #define SYSTEM_FL_FREE_NAME             (1 << 31)
 39 
 40 static inline int system_refcount(struct event_subsystem *system)
 41 {
 42         return system->ref_count & ~SYSTEM_FL_FREE_NAME;
 43 }
 44 
 45 static int system_refcount_inc(struct event_subsystem *system)
 46 {
 47         return (system->ref_count++) & ~SYSTEM_FL_FREE_NAME;
 48 }
 49 
 50 static int system_refcount_dec(struct event_subsystem *system)
 51 {
 52         return (--system->ref_count) & ~SYSTEM_FL_FREE_NAME;
 53 }
 54 
 55 /* Double loops, do not use break, only goto's work */
 56 #define do_for_each_event_file(tr, file)                        \
 57         list_for_each_entry(tr, &ftrace_trace_arrays, list) {   \
 58                 list_for_each_entry(file, &tr->events, list)
 59 
 60 #define do_for_each_event_file_safe(tr, file)                   \
 61         list_for_each_entry(tr, &ftrace_trace_arrays, list) {   \
 62                 struct ftrace_event_file *___n;                         \
 63                 list_for_each_entry_safe(file, ___n, &tr->events, list)
 64 
 65 #define while_for_each_event_file()             \
 66         }
 67 
 68 static struct list_head *
 69 trace_get_fields(struct ftrace_event_call *event_call)
 70 {
 71         if (!event_call->class->get_fields)
 72                 return &event_call->class->fields;
 73         return event_call->class->get_fields(event_call);
 74 }
 75 
 76 static struct ftrace_event_field *
 77 __find_event_field(struct list_head *head, char *name)
 78 {
 79         struct ftrace_event_field *field;
 80 
 81         list_for_each_entry(field, head, link) {
 82                 if (!strcmp(field->name, name))
 83                         return field;
 84         }
 85 
 86         return NULL;
 87 }
 88 
 89 struct ftrace_event_field *
 90 trace_find_event_field(struct ftrace_event_call *call, char *name)
 91 {
 92         struct ftrace_event_field *field;
 93         struct list_head *head;
 94 
 95         field = __find_event_field(&ftrace_common_fields, name);
 96         if (field)
 97                 return field;
 98 
 99         head = trace_get_fields(call);
100         return __find_event_field(head, name);
101 }
102 
103 static int __trace_define_field(struct list_head *head, const char *type,
104                                 const char *name, int offset, int size,
105                                 int is_signed, int filter_type)
106 {
107         struct ftrace_event_field *field;
108 
109         field = kmem_cache_alloc(field_cachep, GFP_TRACE);
110         if (!field)
111                 return -ENOMEM;
112 
113         field->name = name;
114         field->type = type;
115 
116         if (filter_type == FILTER_OTHER)
117                 field->filter_type = filter_assign_type(type);
118         else
119                 field->filter_type = filter_type;
120 
121         field->offset = offset;
122         field->size = size;
123         field->is_signed = is_signed;
124 
125         list_add(&field->link, head);
126 
127         return 0;
128 }
129 
130 int trace_define_field(struct ftrace_event_call *call, const char *type,
131                        const char *name, int offset, int size, int is_signed,
132                        int filter_type)
133 {
134         struct list_head *head;
135 
136         if (WARN_ON(!call->class))
137                 return 0;
138 
139         head = trace_get_fields(call);
140         return __trace_define_field(head, type, name, offset, size,
141                                     is_signed, filter_type);
142 }
143 EXPORT_SYMBOL_GPL(trace_define_field);
144 
145 #define __common_field(type, item)                                      \
146         ret = __trace_define_field(&ftrace_common_fields, #type,        \
147                                    "common_" #item,                     \
148                                    offsetof(typeof(ent), item),         \
149                                    sizeof(ent.item),                    \
150                                    is_signed_type(type), FILTER_OTHER); \
151         if (ret)                                                        \
152                 return ret;
153 
154 static int trace_define_common_fields(void)
155 {
156         int ret;
157         struct trace_entry ent;
158 
159         __common_field(unsigned short, type);
160         __common_field(unsigned char, flags);
161         __common_field(unsigned char, preempt_count);
162         __common_field(int, pid);
163 
164         return ret;
165 }
166 
167 static void trace_destroy_fields(struct ftrace_event_call *call)
168 {
169         struct ftrace_event_field *field, *next;
170         struct list_head *head;
171 
172         head = trace_get_fields(call);
173         list_for_each_entry_safe(field, next, head, link) {
174                 list_del(&field->link);
175                 kmem_cache_free(field_cachep, field);
176         }
177 }
178 
179 int trace_event_raw_init(struct ftrace_event_call *call)
180 {
181         int id;
182 
183         id = register_ftrace_event(&call->event);
184         if (!id)
185                 return -ENODEV;
186 
187         return 0;
188 }
189 EXPORT_SYMBOL_GPL(trace_event_raw_init);
190 
191 int ftrace_event_reg(struct ftrace_event_call *call,
192                      enum trace_reg type, void *data)
193 {
194         struct ftrace_event_file *file = data;
195 
196         switch (type) {
197         case TRACE_REG_REGISTER:
198                 return tracepoint_probe_register(call->name,
199                                                  call->class->probe,
200                                                  file);
201         case TRACE_REG_UNREGISTER:
202                 tracepoint_probe_unregister(call->name,
203                                             call->class->probe,
204                                             file);
205                 return 0;
206 
207 #ifdef CONFIG_PERF_EVENTS
208         case TRACE_REG_PERF_REGISTER:
209                 return tracepoint_probe_register(call->name,
210                                                  call->class->perf_probe,
211                                                  call);
212         case TRACE_REG_PERF_UNREGISTER:
213                 tracepoint_probe_unregister(call->name,
214                                             call->class->perf_probe,
215                                             call);
216                 return 0;
217         case TRACE_REG_PERF_OPEN:
218         case TRACE_REG_PERF_CLOSE:
219         case TRACE_REG_PERF_ADD:
220         case TRACE_REG_PERF_DEL:
221                 return 0;
222 #endif
223         }
224         return 0;
225 }
226 EXPORT_SYMBOL_GPL(ftrace_event_reg);
227 
228 void trace_event_enable_cmd_record(bool enable)
229 {
230         struct ftrace_event_file *file;
231         struct trace_array *tr;
232 
233         mutex_lock(&event_mutex);
234         do_for_each_event_file(tr, file) {
235 
236                 if (!(file->flags & FTRACE_EVENT_FL_ENABLED))
237                         continue;
238 
239                 if (enable) {
240                         tracing_start_cmdline_record();
241                         set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
242                 } else {
243                         tracing_stop_cmdline_record();
244                         clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
245                 }
246         } while_for_each_event_file();
247         mutex_unlock(&event_mutex);
248 }
249 
250 static int __ftrace_event_enable_disable(struct ftrace_event_file *file,
251                                          int enable, int soft_disable)
252 {
253         struct ftrace_event_call *call = file->event_call;
254         int ret = 0;
255         int disable;
256 
257         switch (enable) {
258         case 0:
259                 /*
260                  * When soft_disable is set and enable is cleared, the sm_ref
261                  * reference counter is decremented. If it reaches 0, we want
262                  * to clear the SOFT_DISABLED flag but leave the event in the
263                  * state that it was. That is, if the event was enabled and
264                  * SOFT_DISABLED isn't set, then do nothing. But if SOFT_DISABLED
265                  * is set we do not want the event to be enabled before we
266                  * clear the bit.
267                  *
268                  * When soft_disable is not set but the SOFT_MODE flag is,
269                  * we do nothing. Do not disable the tracepoint, otherwise
270                  * "soft enable"s (clearing the SOFT_DISABLED bit) wont work.
271                  */
272                 if (soft_disable) {
273                         if (atomic_dec_return(&file->sm_ref) > 0)
274                                 break;
275                         disable = file->flags & FTRACE_EVENT_FL_SOFT_DISABLED;
276                         clear_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags);
277                 } else
278                         disable = !(file->flags & FTRACE_EVENT_FL_SOFT_MODE);
279 
280                 if (disable && (file->flags & FTRACE_EVENT_FL_ENABLED)) {
281                         clear_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);
282                         if (file->flags & FTRACE_EVENT_FL_RECORDED_CMD) {
283                                 tracing_stop_cmdline_record();
284                                 clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
285                         }
286                         call->class->reg(call, TRACE_REG_UNREGISTER, file);
287                 }
288                 /* If in SOFT_MODE, just set the SOFT_DISABLE_BIT */
289                 if (file->flags & FTRACE_EVENT_FL_SOFT_MODE)
290                         set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
291                 break;
292         case 1:
293                 /*
294                  * When soft_disable is set and enable is set, we want to
295                  * register the tracepoint for the event, but leave the event
296                  * as is. That means, if the event was already enabled, we do
297                  * nothing (but set SOFT_MODE). If the event is disabled, we
298                  * set SOFT_DISABLED before enabling the event tracepoint, so
299                  * it still seems to be disabled.
300                  */
301                 if (!soft_disable)
302                         clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
303                 else {
304                         if (atomic_inc_return(&file->sm_ref) > 1)
305                                 break;
306                         set_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags);
307                 }
308 
309                 if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) {
310 
311                         /* Keep the event disabled, when going to SOFT_MODE. */
312                         if (soft_disable)
313                                 set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
314 
315                         if (trace_flags & TRACE_ITER_RECORD_CMD) {
316                                 tracing_start_cmdline_record();
317                                 set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
318                         }
319                         ret = call->class->reg(call, TRACE_REG_REGISTER, file);
320                         if (ret) {
321                                 tracing_stop_cmdline_record();
322                                 pr_info("event trace: Could not enable event "
323                                         "%s\n", call->name);
324                                 break;
325                         }
326                         set_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);
327 
328                         /* WAS_ENABLED gets set but never cleared. */
329                         call->flags |= TRACE_EVENT_FL_WAS_ENABLED;
330                 }
331                 break;
332         }
333 
334         return ret;
335 }
336 
337 static int ftrace_event_enable_disable(struct ftrace_event_file *file,
338                                        int enable)
339 {
340         return __ftrace_event_enable_disable(file, enable, 0);
341 }
342 
343 static void ftrace_clear_events(struct trace_array *tr)
344 {
345         struct ftrace_event_file *file;
346 
347         mutex_lock(&event_mutex);
348         list_for_each_entry(file, &tr->events, list) {
349                 ftrace_event_enable_disable(file, 0);
350         }
351         mutex_unlock(&event_mutex);
352 }
353 
354 static void __put_system(struct event_subsystem *system)
355 {
356         struct event_filter *filter = system->filter;
357 
358         WARN_ON_ONCE(system_refcount(system) == 0);
359         if (system_refcount_dec(system))
360                 return;
361 
362         list_del(&system->list);
363 
364         if (filter) {
365                 kfree(filter->filter_string);
366                 kfree(filter);
367         }
368         if (system->ref_count & SYSTEM_FL_FREE_NAME)
369                 kfree(system->name);
370         kfree(system);
371 }
372 
373 static void __get_system(struct event_subsystem *system)
374 {
375         WARN_ON_ONCE(system_refcount(system) == 0);
376         system_refcount_inc(system);
377 }
378 
379 static void __get_system_dir(struct ftrace_subsystem_dir *dir)
380 {
381         WARN_ON_ONCE(dir->ref_count == 0);
382         dir->ref_count++;
383         __get_system(dir->subsystem);
384 }
385 
386 static void __put_system_dir(struct ftrace_subsystem_dir *dir)
387 {
388         WARN_ON_ONCE(dir->ref_count == 0);
389         /* If the subsystem is about to be freed, the dir must be too */
390         WARN_ON_ONCE(system_refcount(dir->subsystem) == 1 && dir->ref_count != 1);
391 
392         __put_system(dir->subsystem);
393         if (!--dir->ref_count)
394                 kfree(dir);
395 }
396 
397 static void put_system(struct ftrace_subsystem_dir *dir)
398 {
399         mutex_lock(&event_mutex);
400         __put_system_dir(dir);
401         mutex_unlock(&event_mutex);
402 }
403 
404 static void remove_subsystem(struct ftrace_subsystem_dir *dir)
405 {
406         if (!dir)
407                 return;
408 
409         if (!--dir->nr_events) {
410                 debugfs_remove_recursive(dir->entry);
411                 list_del(&dir->list);
412                 __put_system_dir(dir);
413         }
414 }
415 
416 static void *event_file_data(struct file *filp)
417 {
418         return ACCESS_ONCE(file_inode(filp)->i_private);
419 }
420 
421 static void remove_event_file_dir(struct ftrace_event_file *file)
422 {
423         struct dentry *dir = file->dir;
424         struct dentry *child;
425 
426         if (dir) {
427                 spin_lock(&dir->d_lock);        /* probably unneeded */
428                 list_for_each_entry(child, &dir->d_subdirs, d_child) {
429                         if (child->d_inode)     /* probably unneeded */
430                                 child->d_inode->i_private = NULL;
431                 }
432                 spin_unlock(&dir->d_lock);
433 
434                 debugfs_remove_recursive(dir);
435         }
436 
437         list_del(&file->list);
438         remove_subsystem(file->system);
439         kmem_cache_free(file_cachep, file);
440 }
441 
442 /*
443  * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
444  */
445 static int
446 __ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
447                               const char *sub, const char *event, int set)
448 {
449         struct ftrace_event_file *file;
450         struct ftrace_event_call *call;
451         int ret = -EINVAL;
452 
453         list_for_each_entry(file, &tr->events, list) {
454 
455                 call = file->event_call;
456 
457                 if (!call->name || !call->class || !call->class->reg)
458                         continue;
459 
460                 if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
461                         continue;
462 
463                 if (match &&
464                     strcmp(match, call->name) != 0 &&
465                     strcmp(match, call->class->system) != 0)
466                         continue;
467 
468                 if (sub && strcmp(sub, call->class->system) != 0)
469                         continue;
470 
471                 if (event && strcmp(event, call->name) != 0)
472                         continue;
473 
474                 ftrace_event_enable_disable(file, set);
475 
476                 ret = 0;
477         }
478 
479         return ret;
480 }
481 
482 static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
483                                   const char *sub, const char *event, int set)
484 {
485         int ret;
486 
487         mutex_lock(&event_mutex);
488         ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set);
489         mutex_unlock(&event_mutex);
490 
491         return ret;
492 }
493 
494 static int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
495 {
496         char *event = NULL, *sub = NULL, *match;
497 
498         /*
499          * The buf format can be <subsystem>:<event-name>
500          *  *:<event-name> means any event by that name.
501          *  :<event-name> is the same.
502          *
503          *  <subsystem>:* means all events in that subsystem
504          *  <subsystem>: means the same.
505          *
506          *  <name> (no ':') means all events in a subsystem with
507          *  the name <name> or any event that matches <name>
508          */
509 
510         match = strsep(&buf, ":");
511         if (buf) {
512                 sub = match;
513                 event = buf;
514                 match = NULL;
515 
516                 if (!strlen(sub) || strcmp(sub, "*") == 0)
517                         sub = NULL;
518                 if (!strlen(event) || strcmp(event, "*") == 0)
519                         event = NULL;
520         }
521 
522         return __ftrace_set_clr_event(tr, match, sub, event, set);
523 }
524 
525 /**
526  * trace_set_clr_event - enable or disable an event
527  * @system: system name to match (NULL for any system)
528  * @event: event name to match (NULL for all events, within system)
529  * @set: 1 to enable, 0 to disable
530  *
531  * This is a way for other parts of the kernel to enable or disable
532  * event recording.
533  *
534  * Returns 0 on success, -EINVAL if the parameters do not match any
535  * registered events.
536  */
537 int trace_set_clr_event(const char *system, const char *event, int set)
538 {
539         struct trace_array *tr = top_trace_array();
540 
541         return __ftrace_set_clr_event(tr, NULL, system, event, set);
542 }
543 EXPORT_SYMBOL_GPL(trace_set_clr_event);
544 
545 /* 128 should be much more than enough */
546 #define EVENT_BUF_SIZE          127
547 
548 static ssize_t
549 ftrace_event_write(struct file *file, const char __user *ubuf,
550                    size_t cnt, loff_t *ppos)
551 {
552         struct trace_parser parser;
553         struct seq_file *m = file->private_data;
554         struct trace_array *tr = m->private;
555         ssize_t read, ret;
556 
557         if (!cnt)
558                 return 0;
559 
560         ret = tracing_update_buffers();
561         if (ret < 0)
562                 return ret;
563 
564         if (trace_parser_get_init(&parser, EVENT_BUF_SIZE + 1))
565                 return -ENOMEM;
566 
567         read = trace_get_user(&parser, ubuf, cnt, ppos);
568 
569         if (read >= 0 && trace_parser_loaded((&parser))) {
570                 int set = 1;
571 
572                 if (*parser.buffer == '!')
573                         set = 0;
574 
575                 parser.buffer[parser.idx] = 0;
576 
577                 ret = ftrace_set_clr_event(tr, parser.buffer + !set, set);
578                 if (ret)
579                         goto out_put;
580         }
581 
582         ret = read;
583 
584  out_put:
585         trace_parser_put(&parser);
586 
587         return ret;
588 }
589 
590 static void *
591 t_next(struct seq_file *m, void *v, loff_t *pos)
592 {
593         struct ftrace_event_file *file = v;
594         struct ftrace_event_call *call;
595         struct trace_array *tr = m->private;
596 
597         (*pos)++;
598 
599         list_for_each_entry_continue(file, &tr->events, list) {
600                 call = file->event_call;
601                 /*
602                  * The ftrace subsystem is for showing formats only.
603                  * They can not be enabled or disabled via the event files.
604                  */
605                 if (call->class && call->class->reg &&
606                     !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
607                         return file;
608         }
609 
610         return NULL;
611 }
612 
613 static void *t_start(struct seq_file *m, loff_t *pos)
614 {
615         struct ftrace_event_file *file;
616         struct trace_array *tr = m->private;
617         loff_t l;
618 
619         mutex_lock(&event_mutex);
620 
621         file = list_entry(&tr->events, struct ftrace_event_file, list);
622         for (l = 0; l <= *pos; ) {
623                 file = t_next(m, file, &l);
624                 if (!file)
625                         break;
626         }
627         return file;
628 }
629 
630 static void *
631 s_next(struct seq_file *m, void *v, loff_t *pos)
632 {
633         struct ftrace_event_file *file = v;
634         struct trace_array *tr = m->private;
635 
636         (*pos)++;
637 
638         list_for_each_entry_continue(file, &tr->events, list) {
639                 if (file->flags & FTRACE_EVENT_FL_ENABLED)
640                         return file;
641         }
642 
643         return NULL;
644 }
645 
646 static void *s_start(struct seq_file *m, loff_t *pos)
647 {
648         struct ftrace_event_file *file;
649         struct trace_array *tr = m->private;
650         loff_t l;
651 
652         mutex_lock(&event_mutex);
653 
654         file = list_entry(&tr->events, struct ftrace_event_file, list);
655         for (l = 0; l <= *pos; ) {
656                 file = s_next(m, file, &l);
657                 if (!file)
658                         break;
659         }
660         return file;
661 }
662 
663 static int t_show(struct seq_file *m, void *v)
664 {
665         struct ftrace_event_file *file = v;
666         struct ftrace_event_call *call = file->event_call;
667 
668         if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
669                 seq_printf(m, "%s:", call->class->system);
670         seq_printf(m, "%s\n", call->name);
671 
672         return 0;
673 }
674 
675 static void t_stop(struct seq_file *m, void *p)
676 {
677         mutex_unlock(&event_mutex);
678 }
679 
680 static ssize_t
681 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
682                   loff_t *ppos)
683 {
684         struct ftrace_event_file *file;
685         unsigned long flags;
686         char *buf;
687 
688         mutex_lock(&event_mutex);
689         file = event_file_data(filp);
690         if (likely(file))
691                 flags = file->flags;
692         mutex_unlock(&event_mutex);
693 
694         if (!file)
695                 return -ENODEV;
696 
697         if (flags & FTRACE_EVENT_FL_ENABLED) {
698                 if (flags & FTRACE_EVENT_FL_SOFT_DISABLED)
699                         buf = "0*\n";
700                 else if (flags & FTRACE_EVENT_FL_SOFT_MODE)
701                         buf = "1*\n";
702                 else
703                         buf = "1\n";
704         } else
705                 buf = "\n";
706 
707         return simple_read_from_buffer(ubuf, cnt, ppos, buf, strlen(buf));
708 }
709 
710 static ssize_t
711 event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
712                    loff_t *ppos)
713 {
714         struct ftrace_event_file *file;
715         unsigned long val;
716         int ret;
717 
718         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
719         if (ret)
720                 return ret;
721 
722         ret = tracing_update_buffers();
723         if (ret < 0)
724                 return ret;
725 
726         switch (val) {
727         case 0:
728         case 1:
729                 ret = -ENODEV;
730                 mutex_lock(&event_mutex);
731                 file = event_file_data(filp);
732                 if (likely(file))
733                         ret = ftrace_event_enable_disable(file, val);
734                 mutex_unlock(&event_mutex);
735                 break;
736 
737         default:
738                 return -EINVAL;
739         }
740 
741         *ppos += cnt;
742 
743         return ret ? ret : cnt;
744 }
745 
746 static ssize_t
747 system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
748                    loff_t *ppos)
749 {
750         const char set_to_char[4] = { '?', '', '1', 'X' };
751         struct ftrace_subsystem_dir *dir = filp->private_data;
752         struct event_subsystem *system = dir->subsystem;
753         struct ftrace_event_call *call;
754         struct ftrace_event_file *file;
755         struct trace_array *tr = dir->tr;
756         char buf[2];
757         int set = 0;
758         int ret;
759 
760         mutex_lock(&event_mutex);
761         list_for_each_entry(file, &tr->events, list) {
762                 call = file->event_call;
763                 if (!call->name || !call->class || !call->class->reg)
764                         continue;
765 
766                 if (system && strcmp(call->class->system, system->name) != 0)
767                         continue;
768 
769                 /*
770                  * We need to find out if all the events are set
771                  * or if all events or cleared, or if we have
772                  * a mixture.
773                  */
774                 set |= (1 << !!(file->flags & FTRACE_EVENT_FL_ENABLED));
775 
776                 /*
777                  * If we have a mixture, no need to look further.
778                  */
779                 if (set == 3)
780                         break;
781         }
782         mutex_unlock(&event_mutex);
783 
784         buf[0] = set_to_char[set];
785         buf[1] = '\n';
786 
787         ret = simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
788 
789         return ret;
790 }
791 
792 static ssize_t
793 system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
794                     loff_t *ppos)
795 {
796         struct ftrace_subsystem_dir *dir = filp->private_data;
797         struct event_subsystem *system = dir->subsystem;
798         const char *name = NULL;
799         unsigned long val;
800         ssize_t ret;
801 
802         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
803         if (ret)
804                 return ret;
805 
806         ret = tracing_update_buffers();
807         if (ret < 0)
808                 return ret;
809 
810         if (val != 0 && val != 1)
811                 return -EINVAL;
812 
813         /*
814          * Opening of "enable" adds a ref count to system,
815          * so the name is safe to use.
816          */
817         if (system)
818                 name = system->name;
819 
820         ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val);
821         if (ret)
822                 goto out;
823 
824         ret = cnt;
825 
826 out:
827         *ppos += cnt;
828 
829         return ret;
830 }
831 
832 enum {
833         FORMAT_HEADER           = 1,
834         FORMAT_FIELD_SEPERATOR  = 2,
835         FORMAT_PRINTFMT         = 3,
836 };
837 
838 static void *f_next(struct seq_file *m, void *v, loff_t *pos)
839 {
840         struct ftrace_event_call *call = event_file_data(m->private);
841         struct ftrace_event_field *field;
842         struct list_head *common_head = &ftrace_common_fields;
843         struct list_head *head = trace_get_fields(call);
844 
845         (*pos)++;
846 
847         switch ((unsigned long)v) {
848         case FORMAT_HEADER:
849                 if (unlikely(list_empty(common_head)))
850                         return NULL;
851 
852                 field = list_entry(common_head->prev,
853                                    struct ftrace_event_field, link);
854                 return field;
855 
856         case FORMAT_FIELD_SEPERATOR:
857                 if (unlikely(list_empty(head)))
858                         return NULL;
859 
860                 field = list_entry(head->prev, struct ftrace_event_field, link);
861                 return field;
862 
863         case FORMAT_PRINTFMT:
864                 /* all done */
865                 return NULL;
866         }
867 
868         field = v;
869         if (field->link.prev == common_head)
870                 return (void *)FORMAT_FIELD_SEPERATOR;
871         else if (field->link.prev == head)
872                 return (void *)FORMAT_PRINTFMT;
873 
874         field = list_entry(field->link.prev, struct ftrace_event_field, link);
875 
876         return field;
877 }
878 
879 static void *f_start(struct seq_file *m, loff_t *pos)
880 {
881         loff_t l = 0;
882         void *p;
883 
884         /* ->stop() is called even if ->start() fails */
885         mutex_lock(&event_mutex);
886         if (!event_file_data(m->private))
887                 return ERR_PTR(-ENODEV);
888 
889         /* Start by showing the header */
890         if (!*pos)
891                 return (void *)FORMAT_HEADER;
892 
893         p = (void *)FORMAT_HEADER;
894         do {
895                 p = f_next(m, p, &l);
896         } while (p && l < *pos);
897 
898         return p;
899 }
900 
901 static int f_show(struct seq_file *m, void *v)
902 {
903         struct ftrace_event_call *call = event_file_data(m->private);
904         struct ftrace_event_field *field;
905         const char *array_descriptor;
906 
907         switch ((unsigned long)v) {
908         case FORMAT_HEADER:
909                 seq_printf(m, "name: %s\n", call->name);
910                 seq_printf(m, "ID: %d\n", call->event.type);
911                 seq_printf(m, "format:\n");
912                 return 0;
913 
914         case FORMAT_FIELD_SEPERATOR:
915                 seq_putc(m, '\n');
916                 return 0;
917 
918         case FORMAT_PRINTFMT:
919                 seq_printf(m, "\nprint fmt: %s\n",
920                            call->print_fmt);
921                 return 0;
922         }
923 
924         field = v;
925 
926         /*
927          * Smartly shows the array type(except dynamic array).
928          * Normal:
929          *      field:TYPE VAR
930          * If TYPE := TYPE[LEN], it is shown:
931          *      field:TYPE VAR[LEN]
932          */
933         array_descriptor = strchr(field->type, '[');
934 
935         if (!strncmp(field->type, "__data_loc", 10))
936                 array_descriptor = NULL;
937 
938         if (!array_descriptor)
939                 seq_printf(m, "\tfield:%s %s;\toffset:%u;\tsize:%u;\tsigned:%d;\n",
940                            field->type, field->name, field->offset,
941                            field->size, !!field->is_signed);
942         else
943                 seq_printf(m, "\tfield:%.*s %s%s;\toffset:%u;\tsize:%u;\tsigned:%d;\n",
944                            (int)(array_descriptor - field->type),
945                            field->type, field->name,
946                            array_descriptor, field->offset,
947                            field->size, !!field->is_signed);
948 
949         return 0;
950 }
951 
952 static void f_stop(struct seq_file *m, void *p)
953 {
954         mutex_unlock(&event_mutex);
955 }
956 
957 static const struct seq_operations trace_format_seq_ops = {
958         .start          = f_start,
959         .next           = f_next,
960         .stop           = f_stop,
961         .show           = f_show,
962 };
963 
964 static int trace_format_open(struct inode *inode, struct file *file)
965 {
966         struct seq_file *m;
967         int ret;
968 
969         ret = seq_open(file, &trace_format_seq_ops);
970         if (ret < 0)
971                 return ret;
972 
973         m = file->private_data;
974         m->private = file;
975 
976         return 0;
977 }
978 
979 static ssize_t
980 event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
981 {
982         int id = (long)event_file_data(filp);
983         struct trace_seq *s;
984         int r;
985 
986         if (*ppos)
987                 return 0;
988 
989         if (unlikely(!id))
990                 return -ENODEV;
991 
992         s = kmalloc(sizeof(*s), GFP_KERNEL);
993         if (!s)
994                 return -ENOMEM;
995 
996         trace_seq_init(s);
997         trace_seq_printf(s, "%d\n", id);
998 
999         r = simple_read_from_buffer(ubuf, cnt, ppos,
1000                                     s->buffer, s->len);
1001         kfree(s);
1002         return r;
1003 }
1004 
1005 static ssize_t
1006 event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
1007                   loff_t *ppos)
1008 {
1009         struct ftrace_event_call *call;
1010         struct trace_seq *s;
1011         int r = -ENODEV;
1012 
1013         if (*ppos)
1014                 return 0;
1015 
1016         s = kmalloc(sizeof(*s), GFP_KERNEL);
1017 
1018         if (!s)
1019                 return -ENOMEM;
1020 
1021         trace_seq_init(s);
1022 
1023         mutex_lock(&event_mutex);
1024         call = event_file_data(filp);
1025         if (call)
1026                 print_event_filter(call, s);
1027         mutex_unlock(&event_mutex);
1028 
1029         if (call)
1030                 r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
1031 
1032         kfree(s);
1033 
1034         return r;
1035 }
1036 
1037 static ssize_t
1038 event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
1039                    loff_t *ppos)
1040 {
1041         struct ftrace_event_call *call;
1042         char *buf;
1043         int err = -ENODEV;
1044 
1045         if (cnt >= PAGE_SIZE)
1046                 return -EINVAL;
1047 
1048         buf = (char *)__get_free_page(GFP_TEMPORARY);
1049         if (!buf)
1050                 return -ENOMEM;
1051 
1052         if (copy_from_user(buf, ubuf, cnt)) {
1053                 free_page((unsigned long) buf);
1054                 return -EFAULT;
1055         }
1056         buf[cnt] = '\0';
1057 
1058         mutex_lock(&event_mutex);
1059         call = event_file_data(filp);
1060         if (call)
1061                 err = apply_event_filter(call, buf);
1062         mutex_unlock(&event_mutex);
1063 
1064         free_page((unsigned long) buf);
1065         if (err < 0)
1066                 return err;
1067 
1068         *ppos += cnt;
1069 
1070         return cnt;
1071 }
1072 
1073 static LIST_HEAD(event_subsystems);
1074 
1075 static int subsystem_open(struct inode *inode, struct file *filp)
1076 {
1077         struct event_subsystem *system = NULL;
1078         struct ftrace_subsystem_dir *dir = NULL; /* Initialize for gcc */
1079         struct trace_array *tr;
1080         int ret;
1081 
1082         /* Make sure the system still exists */
1083         mutex_lock(&trace_types_lock);
1084         mutex_lock(&event_mutex);
1085         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
1086                 list_for_each_entry(dir, &tr->systems, list) {
1087                         if (dir == inode->i_private) {
1088                                 /* Don't open systems with no events */
1089                                 if (dir->nr_events) {
1090                                         __get_system_dir(dir);
1091                                         system = dir->subsystem;
1092                                 }
1093                                 goto exit_loop;
1094                         }
1095                 }
1096         }
1097  exit_loop:
1098         mutex_unlock(&event_mutex);
1099         mutex_unlock(&trace_types_lock);
1100 
1101         if (!system)
1102                 return -ENODEV;
1103 
1104         /* Some versions of gcc think dir can be uninitialized here */
1105         WARN_ON(!dir);
1106 
1107         /* Still need to increment the ref count of the system */
1108         if (trace_array_get(tr) < 0) {
1109                 put_system(dir);
1110                 return -ENODEV;
1111         }
1112 
1113         ret = tracing_open_generic(inode, filp);
1114         if (ret < 0) {
1115                 trace_array_put(tr);
1116                 put_system(dir);
1117         }
1118 
1119         return ret;
1120 }
1121 
1122 static int system_tr_open(struct inode *inode, struct file *filp)
1123 {
1124         struct ftrace_subsystem_dir *dir;
1125         struct trace_array *tr = inode->i_private;
1126         int ret;
1127 
1128         if (trace_array_get(tr) < 0)
1129                 return -ENODEV;
1130 
1131         /* Make a temporary dir that has no system but points to tr */
1132         dir = kzalloc(sizeof(*dir), GFP_KERNEL);
1133         if (!dir) {
1134                 trace_array_put(tr);
1135                 return -ENOMEM;
1136         }
1137 
1138         dir->tr = tr;
1139 
1140         ret = tracing_open_generic(inode, filp);
1141         if (ret < 0) {
1142                 trace_array_put(tr);
1143                 kfree(dir);
1144         }
1145 
1146         filp->private_data = dir;
1147 
1148         return ret;
1149 }
1150 
1151 static int subsystem_release(struct inode *inode, struct file *file)
1152 {
1153         struct ftrace_subsystem_dir *dir = file->private_data;
1154 
1155         trace_array_put(dir->tr);
1156 
1157         /*
1158          * If dir->subsystem is NULL, then this is a temporary
1159          * descriptor that was made for a trace_array to enable
1160          * all subsystems.
1161          */
1162         if (dir->subsystem)
1163                 put_system(dir);
1164         else
1165                 kfree(dir);
1166 
1167         return 0;
1168 }
1169 
1170 static ssize_t
1171 subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
1172                       loff_t *ppos)
1173 {
1174         struct ftrace_subsystem_dir *dir = filp->private_data;
1175         struct event_subsystem *system = dir->subsystem;
1176         struct trace_seq *s;
1177         int r;
1178 
1179         if (*ppos)
1180                 return 0;
1181 
1182         s = kmalloc(sizeof(*s), GFP_KERNEL);
1183         if (!s)
1184                 return -ENOMEM;
1185 
1186         trace_seq_init(s);
1187 
1188         print_subsystem_event_filter(system, s);
1189         r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
1190 
1191         kfree(s);
1192 
1193         return r;
1194 }
1195 
1196 static ssize_t
1197 subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
1198                        loff_t *ppos)
1199 {
1200         struct ftrace_subsystem_dir *dir = filp->private_data;
1201         char *buf;
1202         int err;
1203 
1204         if (cnt >= PAGE_SIZE)
1205                 return -EINVAL;
1206 
1207         buf = (char *)__get_free_page(GFP_TEMPORARY);
1208         if (!buf)
1209                 return -ENOMEM;
1210 
1211         if (copy_from_user(buf, ubuf, cnt)) {
1212                 free_page((unsigned long) buf);
1213                 return -EFAULT;
1214         }
1215         buf[cnt] = '\0';
1216 
1217         err = apply_subsystem_event_filter(dir, buf);
1218         free_page((unsigned long) buf);
1219         if (err < 0)
1220                 return err;
1221 
1222         *ppos += cnt;
1223 
1224         return cnt;
1225 }
1226 
1227 static ssize_t
1228 show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
1229 {
1230         int (*func)(struct trace_seq *s) = filp->private_data;
1231         struct trace_seq *s;
1232         int r;
1233 
1234         if (*ppos)
1235                 return 0;
1236 
1237         s = kmalloc(sizeof(*s), GFP_KERNEL);
1238         if (!s)
1239                 return -ENOMEM;
1240 
1241         trace_seq_init(s);
1242 
1243         func(s);
1244         r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
1245 
1246         kfree(s);
1247 
1248         return r;
1249 }
1250 
1251 static int ftrace_event_avail_open(struct inode *inode, struct file *file);
1252 static int ftrace_event_set_open(struct inode *inode, struct file *file);
1253 static int ftrace_event_release(struct inode *inode, struct file *file);
1254 
1255 static const struct seq_operations show_event_seq_ops = {
1256         .start = t_start,
1257         .next = t_next,
1258         .show = t_show,
1259         .stop = t_stop,
1260 };
1261 
1262 static const struct seq_operations show_set_event_seq_ops = {
1263         .start = s_start,
1264         .next = s_next,
1265         .show = t_show,
1266         .stop = t_stop,
1267 };
1268 
1269 static const struct file_operations ftrace_avail_fops = {
1270         .open = ftrace_event_avail_open,
1271         .read = seq_read,
1272         .llseek = seq_lseek,
1273         .release = seq_release,
1274 };
1275 
1276 static const struct file_operations ftrace_set_event_fops = {
1277         .open = ftrace_event_set_open,
1278         .read = seq_read,
1279         .write = ftrace_event_write,
1280         .llseek = seq_lseek,
1281         .release = ftrace_event_release,
1282 };
1283 
1284 static const struct file_operations ftrace_enable_fops = {
1285         .open = tracing_open_generic,
1286         .read = event_enable_read,
1287         .write = event_enable_write,
1288         .llseek = default_llseek,
1289 };
1290 
1291 static const struct file_operations ftrace_event_format_fops = {
1292         .open = trace_format_open,
1293         .read = seq_read,
1294         .llseek = seq_lseek,
1295         .release = seq_release,
1296 };
1297 
1298 static const struct file_operations ftrace_event_id_fops = {
1299         .read = event_id_read,
1300         .llseek = default_llseek,
1301 };
1302 
1303 static const struct file_operations ftrace_event_filter_fops = {
1304         .open = tracing_open_generic,
1305         .read = event_filter_read,
1306         .write = event_filter_write,
1307         .llseek = default_llseek,
1308 };
1309 
1310 static const struct file_operations ftrace_subsystem_filter_fops = {
1311         .open = subsystem_open,
1312         .read = subsystem_filter_read,
1313         .write = subsystem_filter_write,
1314         .llseek = default_llseek,
1315         .release = subsystem_release,
1316 };
1317 
1318 static const struct file_operations ftrace_system_enable_fops = {
1319         .open = subsystem_open,
1320         .read = system_enable_read,
1321         .write = system_enable_write,
1322         .llseek = default_llseek,
1323         .release = subsystem_release,
1324 };
1325 
1326 static const struct file_operations ftrace_tr_enable_fops = {
1327         .open = system_tr_open,
1328         .read = system_enable_read,
1329         .write = system_enable_write,
1330         .llseek = default_llseek,
1331         .release = subsystem_release,
1332 };
1333 
1334 static const struct file_operations ftrace_show_header_fops = {
1335         .open = tracing_open_generic,
1336         .read = show_header,
1337         .llseek = default_llseek,
1338 };
1339 
1340 static int
1341 ftrace_event_open(struct inode *inode, struct file *file,
1342                   const struct seq_operations *seq_ops)
1343 {
1344         struct seq_file *m;
1345         int ret;
1346 
1347         ret = seq_open(file, seq_ops);
1348         if (ret < 0)
1349                 return ret;
1350         m = file->private_data;
1351         /* copy tr over to seq ops */
1352         m->private = inode->i_private;
1353 
1354         return ret;
1355 }
1356 
1357 static int ftrace_event_release(struct inode *inode, struct file *file)
1358 {
1359         struct trace_array *tr = inode->i_private;
1360 
1361         trace_array_put(tr);
1362 
1363         return seq_release(inode, file);
1364 }
1365 
1366 static int
1367 ftrace_event_avail_open(struct inode *inode, struct file *file)
1368 {
1369         const struct seq_operations *seq_ops = &show_event_seq_ops;
1370 
1371         return ftrace_event_open(inode, file, seq_ops);
1372 }
1373 
1374 static int
1375 ftrace_event_set_open(struct inode *inode, struct file *file)
1376 {
1377         const struct seq_operations *seq_ops = &show_set_event_seq_ops;
1378         struct trace_array *tr = inode->i_private;
1379         int ret;
1380 
1381         if (trace_array_get(tr) < 0)
1382                 return -ENODEV;
1383 
1384         if ((file->f_mode & FMODE_WRITE) &&
1385             (file->f_flags & O_TRUNC))
1386                 ftrace_clear_events(tr);
1387 
1388         ret = ftrace_event_open(inode, file, seq_ops);
1389         if (ret < 0)
1390                 trace_array_put(tr);
1391         return ret;
1392 }
1393 
1394 static struct event_subsystem *
1395 create_new_subsystem(const char *name)
1396 {
1397         struct event_subsystem *system;
1398 
1399         /* need to create new entry */
1400         system = kmalloc(sizeof(*system), GFP_KERNEL);
1401         if (!system)
1402                 return NULL;
1403 
1404         system->ref_count = 1;
1405 
1406         /* Only allocate if dynamic (kprobes and modules) */
1407         if (!core_kernel_data((unsigned long)name)) {
1408                 system->ref_count |= SYSTEM_FL_FREE_NAME;
1409                 system->name = kstrdup(name, GFP_KERNEL);
1410                 if (!system->name)
1411                         goto out_free;
1412         } else
1413                 system->name = name;
1414 
1415         system->filter = NULL;
1416 
1417         system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
1418         if (!system->filter)
1419                 goto out_free;
1420 
1421         list_add(&system->list, &event_subsystems);
1422 
1423         return system;
1424 
1425  out_free:
1426         if (system->ref_count & SYSTEM_FL_FREE_NAME)
1427                 kfree(system->name);
1428         kfree(system);
1429         return NULL;
1430 }
1431 
1432 static struct dentry *
1433 event_subsystem_dir(struct trace_array *tr, const char *name,
1434                     struct ftrace_event_file *file, struct dentry *parent)
1435 {
1436         struct ftrace_subsystem_dir *dir;
1437         struct event_subsystem *system;
1438         struct dentry *entry;
1439 
1440         /* First see if we did not already create this dir */
1441         list_for_each_entry(dir, &tr->systems, list) {
1442                 system = dir->subsystem;
1443                 if (strcmp(system->name, name) == 0) {
1444                         dir->nr_events++;
1445                         file->system = dir;
1446                         return dir->entry;
1447                 }
1448         }
1449 
1450         /* Now see if the system itself exists. */
1451         list_for_each_entry(system, &event_subsystems, list) {
1452                 if (strcmp(system->name, name) == 0)
1453                         break;
1454         }
1455         /* Reset system variable when not found */
1456         if (&system->list == &event_subsystems)
1457                 system = NULL;
1458 
1459         dir = kmalloc(sizeof(*dir), GFP_KERNEL);
1460         if (!dir)
1461                 goto out_fail;
1462 
1463         if (!system) {
1464                 system = create_new_subsystem(name);
1465                 if (!system)
1466                         goto out_free;
1467         } else
1468                 __get_system(system);
1469 
1470         dir->entry = debugfs_create_dir(name, parent);
1471         if (!dir->entry) {
1472                 pr_warning("Failed to create system directory %s\n", name);
1473                 __put_system(system);
1474                 goto out_free;
1475         }
1476 
1477         dir->tr = tr;
1478         dir->ref_count = 1;
1479         dir->nr_events = 1;
1480         dir->subsystem = system;
1481         file->system = dir;
1482 
1483         entry = debugfs_create_file("filter", 0644, dir->entry, dir,
1484                                     &ftrace_subsystem_filter_fops);
1485         if (!entry) {
1486                 kfree(system->filter);
1487                 system->filter = NULL;
1488                 pr_warning("Could not create debugfs '%s/filter' entry\n", name);
1489         }
1490 
1491         trace_create_file("enable", 0644, dir->entry, dir,
1492                           &ftrace_system_enable_fops);
1493 
1494         list_add(&dir->list, &tr->systems);
1495 
1496         return dir->entry;
1497 
1498  out_free:
1499         kfree(dir);
1500  out_fail:
1501         /* Only print this message if failed on memory allocation */
1502         if (!dir || !system)
1503                 pr_warning("No memory to create event subsystem %s\n",
1504                            name);
1505         return NULL;
1506 }
1507 
1508 static int
1509 event_create_dir(struct dentry *parent,
1510                  struct ftrace_event_file *file,
1511                  const struct file_operations *id,
1512                  const struct file_operations *enable,
1513                  const struct file_operations *filter,
1514                  const struct file_operations *format)
1515 {
1516         struct ftrace_event_call *call = file->event_call;
1517         struct trace_array *tr = file->tr;
1518         struct list_head *head;
1519         struct dentry *d_events;
1520         int ret;
1521 
1522         /*
1523          * If the trace point header did not define TRACE_SYSTEM
1524          * then the system would be called "TRACE_SYSTEM".
1525          */
1526         if (strcmp(call->class->system, TRACE_SYSTEM) != 0) {
1527                 d_events = event_subsystem_dir(tr, call->class->system, file, parent);
1528                 if (!d_events)
1529                         return -ENOMEM;
1530         } else
1531                 d_events = parent;
1532 
1533         file->dir = debugfs_create_dir(call->name, d_events);
1534         if (!file->dir) {
1535                 pr_warning("Could not create debugfs '%s' directory\n",
1536                            call->name);
1537                 return -1;
1538         }
1539 
1540         if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
1541                 trace_create_file("enable", 0644, file->dir, file,
1542                                   enable);
1543 
1544 #ifdef CONFIG_PERF_EVENTS
1545         if (call->event.type && call->class->reg)
1546                 trace_create_file("id", 0444, file->dir,
1547                                   (void *)(long)call->event.type, id);
1548 #endif
1549 
1550         /*
1551          * Other events may have the same class. Only update
1552          * the fields if they are not already defined.
1553          */
1554         head = trace_get_fields(call);
1555         if (list_empty(head)) {
1556                 ret = call->class->define_fields(call);
1557                 if (ret < 0) {
1558                         pr_warning("Could not initialize trace point"
1559                                    " events/%s\n", call->name);
1560                         return -1;
1561                 }
1562         }
1563         trace_create_file("filter", 0644, file->dir, call,
1564                           filter);
1565 
1566         trace_create_file("format", 0444, file->dir, call,
1567                           format);
1568 
1569         return 0;
1570 }
1571 
1572 static void remove_event_from_tracers(struct ftrace_event_call *call)
1573 {
1574         struct ftrace_event_file *file;
1575         struct trace_array *tr;
1576 
1577         do_for_each_event_file_safe(tr, file) {
1578                 if (file->event_call != call)
1579                         continue;
1580 
1581                 remove_event_file_dir(file);
1582                 /*
1583                  * The do_for_each_event_file_safe() is
1584                  * a double loop. After finding the call for this
1585                  * trace_array, we use break to jump to the next
1586                  * trace_array.
1587                  */
1588                 break;
1589         } while_for_each_event_file();
1590 }
1591 
1592 static void event_remove(struct ftrace_event_call *call)
1593 {
1594         struct trace_array *tr;
1595         struct ftrace_event_file *file;
1596 
1597         do_for_each_event_file(tr, file) {
1598                 if (file->event_call != call)
1599                         continue;
1600                 ftrace_event_enable_disable(file, 0);
1601                 /*
1602                  * The do_for_each_event_file() is
1603                  * a double loop. After finding the call for this
1604                  * trace_array, we use break to jump to the next
1605                  * trace_array.
1606                  */
1607                 break;
1608         } while_for_each_event_file();
1609 
1610         if (call->event.funcs)
1611                 __unregister_ftrace_event(&call->event);
1612         remove_event_from_tracers(call);
1613         list_del(&call->list);
1614 }
1615 
1616 static int event_init(struct ftrace_event_call *call)
1617 {
1618         int ret = 0;
1619 
1620         if (WARN_ON(!call->name))
1621                 return -EINVAL;
1622 
1623         if (call->class->raw_init) {
1624                 ret = call->class->raw_init(call);
1625                 if (ret < 0 && ret != -ENOSYS)
1626                         pr_warn("Could not initialize trace events/%s\n",
1627                                 call->name);
1628         }
1629 
1630         return ret;
1631 }
1632 
1633 static int
1634 __register_event(struct ftrace_event_call *call, struct module *mod)
1635 {
1636         int ret;
1637 
1638         ret = event_init(call);
1639         if (ret < 0)
1640                 return ret;
1641 
1642         list_add(&call->list, &ftrace_events);
1643         call->mod = mod;
1644 
1645         return 0;
1646 }
1647 
1648 static struct ftrace_event_file *
1649 trace_create_new_event(struct ftrace_event_call *call,
1650                        struct trace_array *tr)
1651 {
1652         struct ftrace_event_file *file;
1653 
1654         file = kmem_cache_alloc(file_cachep, GFP_TRACE);
1655         if (!file)
1656                 return NULL;
1657 
1658         file->event_call = call;
1659         file->tr = tr;
1660         atomic_set(&file->sm_ref, 0);
1661         list_add(&file->list, &tr->events);
1662 
1663         return file;
1664 }
1665 
1666 /* Add an event to a trace directory */
1667 static int
1668 __trace_add_new_event(struct ftrace_event_call *call,
1669                       struct trace_array *tr,
1670                       const struct file_operations *id,
1671                       const struct file_operations *enable,
1672                       const struct file_operations *filter,
1673                       const struct file_operations *format)
1674 {
1675         struct ftrace_event_file *file;
1676 
1677         file = trace_create_new_event(call, tr);
1678         if (!file)
1679                 return -ENOMEM;
1680 
1681         return event_create_dir(tr->event_dir, file, id, enable, filter, format);
1682 }
1683 
1684 /*
1685  * Just create a decriptor for early init. A descriptor is required
1686  * for enabling events at boot. We want to enable events before
1687  * the filesystem is initialized.
1688  */
1689 static __init int
1690 __trace_early_add_new_event(struct ftrace_event_call *call,
1691                             struct trace_array *tr)
1692 {
1693         struct ftrace_event_file *file;
1694 
1695         file = trace_create_new_event(call, tr);
1696         if (!file)
1697                 return -ENOMEM;
1698 
1699         return 0;
1700 }
1701 
1702 struct ftrace_module_file_ops;
1703 static void __add_event_to_tracers(struct ftrace_event_call *call,
1704                                    struct ftrace_module_file_ops *file_ops);
1705 
1706 /* Add an additional event_call dynamically */
1707 int trace_add_event_call(struct ftrace_event_call *call)
1708 {
1709         int ret;
1710         mutex_lock(&trace_types_lock);
1711         mutex_lock(&event_mutex);
1712 
1713         ret = __register_event(call, NULL);
1714         if (ret >= 0)
1715                 __add_event_to_tracers(call, NULL);
1716 
1717         mutex_unlock(&event_mutex);
1718         mutex_unlock(&trace_types_lock);
1719         return ret;
1720 }
1721 
1722 /*
1723  * Must be called under locking of trace_types_lock, event_mutex and
1724  * trace_event_sem.
1725  */
1726 static void __trace_remove_event_call(struct ftrace_event_call *call)
1727 {
1728         event_remove(call);
1729         trace_destroy_fields(call);
1730         destroy_preds(call);
1731 }
1732 
1733 static int probe_remove_event_call(struct ftrace_event_call *call)
1734 {
1735         struct trace_array *tr;
1736         struct ftrace_event_file *file;
1737 
1738 #ifdef CONFIG_PERF_EVENTS
1739         if (call->perf_refcount)
1740                 return -EBUSY;
1741 #endif
1742         do_for_each_event_file(tr, file) {
1743                 if (file->event_call != call)
1744                         continue;
1745                 /*
1746                  * We can't rely on ftrace_event_enable_disable(enable => 0)
1747                  * we are going to do, FTRACE_EVENT_FL_SOFT_MODE can suppress
1748                  * TRACE_REG_UNREGISTER.
1749                  */
1750                 if (file->flags & FTRACE_EVENT_FL_ENABLED)
1751                         return -EBUSY;
1752                 break;
1753         } while_for_each_event_file();
1754 
1755         __trace_remove_event_call(call);
1756 
1757         return 0;
1758 }
1759 
1760 /* Remove an event_call */
1761 int trace_remove_event_call(struct ftrace_event_call *call)
1762 {
1763         int ret;
1764 
1765         mutex_lock(&trace_types_lock);
1766         mutex_lock(&event_mutex);
1767         down_write(&trace_event_sem);
1768         ret = probe_remove_event_call(call);
1769         up_write(&trace_event_sem);
1770         mutex_unlock(&event_mutex);
1771         mutex_unlock(&trace_types_lock);
1772 
1773         return ret;
1774 }
1775 
1776 #define for_each_event(event, start, end)                       \
1777         for (event = start;                                     \
1778              (unsigned long)event < (unsigned long)end;         \
1779              event++)
1780 
1781 #ifdef CONFIG_MODULES
1782 
1783 static LIST_HEAD(ftrace_module_file_list);
1784 
1785 /*
1786  * Modules must own their file_operations to keep up with
1787  * reference counting.
1788  */
1789 struct ftrace_module_file_ops {
1790         struct list_head                list;
1791         struct module                   *mod;
1792         struct file_operations          id;
1793         struct file_operations          enable;
1794         struct file_operations          format;
1795         struct file_operations          filter;
1796 };
1797 
1798 static struct ftrace_module_file_ops *
1799 find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
1800 {
1801         /*
1802          * As event_calls are added in groups by module,
1803          * when we find one file_ops, we don't need to search for
1804          * each call in that module, as the rest should be the
1805          * same. Only search for a new one if the last one did
1806          * not match.
1807          */
1808         if (file_ops && mod == file_ops->mod)
1809                 return file_ops;
1810 
1811         list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
1812                 if (file_ops->mod == mod)
1813                         return file_ops;
1814         }
1815         return NULL;
1816 }
1817 
1818 static struct ftrace_module_file_ops *
1819 trace_create_file_ops(struct module *mod)
1820 {
1821         struct ftrace_module_file_ops *file_ops;
1822 
1823         /*
1824          * This is a bit of a PITA. To allow for correct reference
1825          * counting, modules must "own" their file_operations.
1826          * To do this, we allocate the file operations that will be
1827          * used in the event directory.
1828          */
1829 
1830         file_ops = kmalloc(sizeof(*file_ops), GFP_KERNEL);
1831         if (!file_ops)
1832                 return NULL;
1833 
1834         file_ops->mod = mod;
1835 
1836         file_ops->id = ftrace_event_id_fops;
1837         file_ops->id.owner = mod;
1838 
1839         file_ops->enable = ftrace_enable_fops;
1840         file_ops->enable.owner = mod;
1841 
1842         file_ops->filter = ftrace_event_filter_fops;
1843         file_ops->filter.owner = mod;
1844 
1845         file_ops->format = ftrace_event_format_fops;
1846         file_ops->format.owner = mod;
1847 
1848         list_add(&file_ops->list, &ftrace_module_file_list);
1849 
1850         return file_ops;
1851 }
1852 
1853 static void trace_module_add_events(struct module *mod)
1854 {
1855         struct ftrace_module_file_ops *file_ops = NULL;
1856         struct ftrace_event_call **call, **start, **end;
1857 
1858         if (!mod->num_trace_events)
1859                 return;
1860 
1861         /* Don't add infrastructure for mods without tracepoints */
1862         if (trace_module_has_bad_taint(mod)) {
1863                 pr_err("%s: module has bad taint, not creating trace events\n",
1864                        mod->name);
1865                 return;
1866         }
1867 
1868         start = mod->trace_events;
1869         end = mod->trace_events + mod->num_trace_events;
1870 
1871         if (start == end)
1872                 return;
1873 
1874         file_ops = trace_create_file_ops(mod);
1875         if (!file_ops)
1876                 return;
1877 
1878         for_each_event(call, start, end) {
1879                 __register_event(*call, mod);
1880                 __add_event_to_tracers(*call, file_ops);
1881         }
1882 }
1883 
1884 static void trace_module_remove_events(struct module *mod)
1885 {
1886         struct ftrace_module_file_ops *file_ops;
1887         struct ftrace_event_call *call, *p;
1888         bool clear_trace = false;
1889 
1890         down_write(&trace_event_sem);
1891         list_for_each_entry_safe(call, p, &ftrace_events, list) {
1892                 if (call->mod == mod) {
1893                         if (call->flags & TRACE_EVENT_FL_WAS_ENABLED)
1894                                 clear_trace = true;
1895                         __trace_remove_event_call(call);
1896                 }
1897         }
1898 
1899         /* Now free the file_operations */
1900         list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
1901                 if (file_ops->mod == mod)
1902                         break;
1903         }
1904         if (&file_ops->list != &ftrace_module_file_list) {
1905                 list_del(&file_ops->list);
1906                 kfree(file_ops);
1907         }
1908         up_write(&trace_event_sem);
1909 
1910         /*
1911          * It is safest to reset the ring buffer if the module being unloaded
1912          * registered any events that were used. The only worry is if
1913          * a new module gets loaded, and takes on the same id as the events
1914          * of this module. When printing out the buffer, traced events left
1915          * over from this module may be passed to the new module events and
1916          * unexpected results may occur.
1917          */
1918         if (clear_trace)
1919                 tracing_reset_all_online_cpus();
1920 }
1921 
1922 static int trace_module_notify(struct notifier_block *self,
1923                                unsigned long val, void *data)
1924 {
1925         struct module *mod = data;
1926 
1927         mutex_lock(&trace_types_lock);
1928         mutex_lock(&event_mutex);
1929         switch (val) {
1930         case MODULE_STATE_COMING:
1931                 trace_module_add_events(mod);
1932                 break;
1933         case MODULE_STATE_GOING:
1934                 trace_module_remove_events(mod);
1935                 break;
1936         }
1937         mutex_unlock(&event_mutex);
1938         mutex_unlock(&trace_types_lock);
1939 
1940         return 0;
1941 }
1942 
1943 static int
1944 __trace_add_new_mod_event(struct ftrace_event_call *call,
1945                           struct trace_array *tr,
1946                           struct ftrace_module_file_ops *file_ops)
1947 {
1948         return __trace_add_new_event(call, tr,
1949                                      &file_ops->id, &file_ops->enable,
1950                                      &file_ops->filter, &file_ops->format);
1951 }
1952 
1953 #else
1954 static inline struct ftrace_module_file_ops *
1955 find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
1956 {
1957         return NULL;
1958 }
1959 static inline int trace_module_notify(struct notifier_block *self,
1960                                       unsigned long val, void *data)
1961 {
1962         return 0;
1963 }
1964 static inline int
1965 __trace_add_new_mod_event(struct ftrace_event_call *call,
1966                           struct trace_array *tr,
1967                           struct ftrace_module_file_ops *file_ops)
1968 {
1969         return -ENODEV;
1970 }
1971 #endif /* CONFIG_MODULES */
1972 
1973 /* Create a new event directory structure for a trace directory. */
1974 static void
1975 __trace_add_event_dirs(struct trace_array *tr)
1976 {
1977         struct ftrace_module_file_ops *file_ops = NULL;
1978         struct ftrace_event_call *call;
1979         int ret;
1980 
1981         list_for_each_entry(call, &ftrace_events, list) {
1982                 if (call->mod) {
1983                         /*
1984                          * Directories for events by modules need to
1985                          * keep module ref counts when opened (as we don't
1986                          * want the module to disappear when reading one
1987                          * of these files). The file_ops keep account of
1988                          * the module ref count.
1989                          */
1990                         file_ops = find_ftrace_file_ops(file_ops, call->mod);
1991                         if (!file_ops)
1992                                 continue; /* Warn? */
1993                         ret = __trace_add_new_mod_event(call, tr, file_ops);
1994                         if (ret < 0)
1995                                 pr_warning("Could not create directory for event %s\n",
1996                                            call->name);
1997                         continue;
1998                 }
1999                 ret = __trace_add_new_event(call, tr,
2000                                             &ftrace_event_id_fops,
2001                                             &ftrace_enable_fops,
2002                                             &ftrace_event_filter_fops,
2003                                             &ftrace_event_format_fops);
2004                 if (ret < 0)
2005                         pr_warning("Could not create directory for event %s\n",
2006                                    call->name);
2007         }
2008 }
2009 
2010 #ifdef CONFIG_DYNAMIC_FTRACE
2011 
2012 /* Avoid typos */
2013 #define ENABLE_EVENT_STR        "enable_event"
2014 #define DISABLE_EVENT_STR       "disable_event"
2015 
2016 struct event_probe_data {
2017         struct ftrace_event_file        *file;
2018         unsigned long                   count;
2019         int                             ref;
2020         bool                            enable;
2021 };
2022 
2023 static struct ftrace_event_file *
2024 find_event_file(struct trace_array *tr, const char *system,  const char *event)
2025 {
2026         struct ftrace_event_file *file;
2027         struct ftrace_event_call *call;
2028 
2029         list_for_each_entry(file, &tr->events, list) {
2030 
2031                 call = file->event_call;
2032 
2033                 if (!call->name || !call->class || !call->class->reg)
2034                         continue;
2035 
2036                 if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
2037                         continue;
2038 
2039                 if (strcmp(event, call->name) == 0 &&
2040                     strcmp(system, call->class->system) == 0)
2041                         return file;
2042         }
2043         return NULL;
2044 }
2045 
2046 static void
2047 event_enable_probe(unsigned long ip, unsigned long parent_ip, void **_data)
2048 {
2049         struct event_probe_data **pdata = (struct event_probe_data **)_data;
2050         struct event_probe_data *data = *pdata;
2051 
2052         if (!data)
2053                 return;
2054 
2055         if (data->enable)
2056                 clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
2057         else
2058                 set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
2059 }
2060 
2061 static void
2062 event_enable_count_probe(unsigned long ip, unsigned long parent_ip, void **_data)
2063 {
2064         struct event_probe_data **pdata = (struct event_probe_data **)_data;
2065         struct event_probe_data *data = *pdata;
2066 
2067         if (!data)
2068                 return;
2069 
2070         if (!data->count)
2071                 return;
2072 
2073         /* Skip if the event is in a state we want to switch to */
2074         if (data->enable == !(data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
2075                 return;
2076 
2077         if (data->count != -1)
2078                 (data->count)--;
2079 
2080         event_enable_probe(ip, parent_ip, _data);
2081 }
2082 
2083 static int
2084 event_enable_print(struct seq_file *m, unsigned long ip,
2085                       struct ftrace_probe_ops *ops, void *_data)
2086 {
2087         struct event_probe_data *data = _data;
2088 
2089         seq_printf(m, "%ps:", (void *)ip);
2090 
2091         seq_printf(m, "%s:%s:%s",
2092                    data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
2093                    data->file->event_call->class->system,
2094                    data->file->event_call->name);
2095 
2096         if (data->count == -1)
2097                 seq_printf(m, ":unlimited\n");
2098         else
2099                 seq_printf(m, ":count=%ld\n", data->count);
2100 
2101         return 0;
2102 }
2103 
2104 static int
2105 event_enable_init(struct ftrace_probe_ops *ops, unsigned long ip,
2106                   void **_data)
2107 {
2108         struct event_probe_data **pdata = (struct event_probe_data **)_data;
2109         struct event_probe_data *data = *pdata;
2110 
2111         data->ref++;
2112         return 0;
2113 }
2114 
2115 static void
2116 event_enable_free(struct ftrace_probe_ops *ops, unsigned long ip,
2117                   void **_data)
2118 {
2119         struct event_probe_data **pdata = (struct event_probe_data **)_data;
2120         struct event_probe_data *data = *pdata;
2121 
2122         if (WARN_ON_ONCE(data->ref <= 0))
2123                 return;
2124 
2125         data->ref--;
2126         if (!data->ref) {
2127                 /* Remove the SOFT_MODE flag */
2128                 __ftrace_event_enable_disable(data->file, 0, 1);
2129                 module_put(data->file->event_call->mod);
2130                 kfree(data);
2131         }
2132         *pdata = NULL;
2133 }
2134 
2135 static struct ftrace_probe_ops event_enable_probe_ops = {
2136         .func                   = event_enable_probe,
2137         .print                  = event_enable_print,
2138         .init                   = event_enable_init,
2139         .free                   = event_enable_free,
2140 };
2141 
2142 static struct ftrace_probe_ops event_enable_count_probe_ops = {
2143         .func                   = event_enable_count_probe,
2144         .print                  = event_enable_print,
2145         .init                   = event_enable_init,
2146         .free                   = event_enable_free,
2147 };
2148 
2149 static struct ftrace_probe_ops event_disable_probe_ops = {
2150         .func                   = event_enable_probe,
2151         .print                  = event_enable_print,
2152         .init                   = event_enable_init,
2153         .free                   = event_enable_free,
2154 };
2155 
2156 static struct ftrace_probe_ops event_disable_count_probe_ops = {
2157         .func                   = event_enable_count_probe,
2158         .print                  = event_enable_print,
2159         .init                   = event_enable_init,
2160         .free                   = event_enable_free,
2161 };
2162 
2163 static int
2164 event_enable_func(struct ftrace_hash *hash,
2165                   char *glob, char *cmd, char *param, int enabled)
2166 {
2167         struct trace_array *tr = top_trace_array();
2168         struct ftrace_event_file *file;
2169         struct ftrace_probe_ops *ops;
2170         struct event_probe_data *data;
2171         const char *system;
2172         const char *event;
2173         char *number;
2174         bool enable;
2175         int ret;
2176 
2177         /* hash funcs only work with set_ftrace_filter */
2178         if (!enabled)
2179                 return -EINVAL;
2180 
2181         if (!param)
2182                 return -EINVAL;
2183 
2184         system = strsep(&param, ":");
2185         if (!param)
2186                 return -EINVAL;
2187 
2188         event = strsep(&param, ":");
2189 
2190         mutex_lock(&event_mutex);
2191 
2192         ret = -EINVAL;
2193         file = find_event_file(tr, system, event);
2194         if (!file)
2195                 goto out;
2196 
2197         enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
2198 
2199         if (enable)
2200                 ops = param ? &event_enable_count_probe_ops : &event_enable_probe_ops;
2201         else
2202                 ops = param ? &event_disable_count_probe_ops : &event_disable_probe_ops;
2203 
2204         if (glob[0] == '!') {
2205                 unregister_ftrace_function_probe_func(glob+1, ops);
2206                 ret = 0;
2207                 goto out;
2208         }
2209 
2210         ret = -ENOMEM;
2211         data = kzalloc(sizeof(*data), GFP_KERNEL);
2212         if (!data)
2213                 goto out;
2214 
2215         data->enable = enable;
2216         data->count = -1;
2217         data->file = file;
2218 
2219         if (!param)
2220                 goto out_reg;
2221 
2222         number = strsep(&param, ":");
2223 
2224         ret = -EINVAL;
2225         if (!strlen(number))
2226                 goto out_free;
2227 
2228         /*
2229          * We use the callback data field (which is a pointer)
2230          * as our counter.
2231          */
2232         ret = kstrtoul(number, 0, &data->count);
2233         if (ret)
2234                 goto out_free;
2235 
2236  out_reg:
2237         /* Don't let event modules unload while probe registered */
2238         ret = try_module_get(file->event_call->mod);
2239         if (!ret) {
2240                 ret = -EBUSY;
2241                 goto out_free;
2242         }
2243 
2244         ret = __ftrace_event_enable_disable(file, 1, 1);
2245         if (ret < 0)
2246                 goto out_put;
2247         ret = register_ftrace_function_probe(glob, ops, data);
2248         /*
2249          * The above returns on success the # of functions enabled,
2250          * but if it didn't find any functions it returns zero.
2251          * Consider no functions a failure too.
2252          */
2253         if (!ret) {
2254                 ret = -ENOENT;
2255                 goto out_disable;
2256         } else if (ret < 0)
2257                 goto out_disable;
2258         /* Just return zero, not the number of enabled functions */
2259         ret = 0;
2260  out:
2261         mutex_unlock(&event_mutex);
2262         return ret;
2263 
2264  out_disable:
2265         __ftrace_event_enable_disable(file, 0, 1);
2266  out_put:
2267         module_put(file->event_call->mod);
2268  out_free:
2269         kfree(data);
2270         goto out;
2271 }
2272 
2273 static struct ftrace_func_command event_enable_cmd = {
2274         .name                   = ENABLE_EVENT_STR,
2275         .func                   = event_enable_func,
2276 };
2277 
2278 static struct ftrace_func_command event_disable_cmd = {
2279         .name                   = DISABLE_EVENT_STR,
2280         .func                   = event_enable_func,
2281 };
2282 
2283 static __init int register_event_cmds(void)
2284 {
2285         int ret;
2286 
2287         ret = register_ftrace_command(&event_enable_cmd);
2288         if (WARN_ON(ret < 0))
2289                 return ret;
2290         ret = register_ftrace_command(&event_disable_cmd);
2291         if (WARN_ON(ret < 0))
2292                 unregister_ftrace_command(&event_enable_cmd);
2293         return ret;
2294 }
2295 #else
2296 static inline int register_event_cmds(void) { return 0; }
2297 #endif /* CONFIG_DYNAMIC_FTRACE */
2298 
2299 /*
2300  * The top level array has already had its ftrace_event_file
2301  * descriptors created in order to allow for early events to
2302  * be recorded. This function is called after the debugfs has been
2303  * initialized, and we now have to create the files associated
2304  * to the events.
2305  */
2306 static __init void
2307 __trace_early_add_event_dirs(struct trace_array *tr)
2308 {
2309         struct ftrace_event_file *file;
2310         int ret;
2311 
2312 
2313         list_for_each_entry(file, &tr->events, list) {
2314                 ret = event_create_dir(tr->event_dir, file,
2315                                        &ftrace_event_id_fops,
2316                                        &ftrace_enable_fops,
2317                                        &ftrace_event_filter_fops,
2318                                        &ftrace_event_format_fops);
2319                 if (ret < 0)
2320                         pr_warning("Could not create directory for event %s\n",
2321                                    file->event_call->name);
2322         }
2323 }
2324 
2325 /*
2326  * For early boot up, the top trace array requires to have
2327  * a list of events that can be enabled. This must be done before
2328  * the filesystem is set up in order to allow events to be traced
2329  * early.
2330  */
2331 static __init void
2332 __trace_early_add_events(struct trace_array *tr)
2333 {
2334         struct ftrace_event_call *call;
2335         int ret;
2336 
2337         list_for_each_entry(call, &ftrace_events, list) {
2338                 /* Early boot up should not have any modules loaded */
2339                 if (WARN_ON_ONCE(call->mod))
2340                         continue;
2341 
2342                 ret = __trace_early_add_new_event(call, tr);
2343                 if (ret < 0)
2344                         pr_warning("Could not create early event %s\n",
2345                                    call->name);
2346         }
2347 }
2348 
2349 /* Remove the event directory structure for a trace directory. */
2350 static void
2351 __trace_remove_event_dirs(struct trace_array *tr)
2352 {
2353         struct ftrace_event_file *file, *next;
2354 
2355         list_for_each_entry_safe(file, next, &tr->events, list)
2356                 remove_event_file_dir(file);
2357 }
2358 
2359 static void
2360 __add_event_to_tracers(struct ftrace_event_call *call,
2361                        struct ftrace_module_file_ops *file_ops)
2362 {
2363         struct trace_array *tr;
2364 
2365         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
2366                 if (file_ops)
2367                         __trace_add_new_mod_event(call, tr, file_ops);
2368                 else
2369                         __trace_add_new_event(call, tr,
2370                                               &ftrace_event_id_fops,
2371                                               &ftrace_enable_fops,
2372                                               &ftrace_event_filter_fops,
2373                                               &ftrace_event_format_fops);
2374         }
2375 }
2376 
2377 static struct notifier_block trace_module_nb = {
2378         .notifier_call = trace_module_notify,
2379         .priority = 0,
2380 };
2381 
2382 extern struct ftrace_event_call *__start_ftrace_events[];
2383 extern struct ftrace_event_call *__stop_ftrace_events[];
2384 
2385 static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;
2386 
2387 static __init int setup_trace_event(char *str)
2388 {
2389         strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
2390         ring_buffer_expanded = true;
2391         tracing_selftest_disabled = true;
2392 
2393         return 1;
2394 }
2395 __setup("trace_event=", setup_trace_event);
2396 
2397 /* Expects to have event_mutex held when called */
2398 static int
2399 create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
2400 {
2401         struct dentry *d_events;
2402         struct dentry *entry;
2403 
2404         entry = debugfs_create_file("set_event", 0644, parent,
2405                                     tr, &ftrace_set_event_fops);
2406         if (!entry) {
2407                 pr_warning("Could not create debugfs 'set_event' entry\n");
2408                 return -ENOMEM;
2409         }
2410 
2411         d_events = debugfs_create_dir("events", parent);
2412         if (!d_events) {
2413                 pr_warning("Could not create debugfs 'events' directory\n");
2414                 return -ENOMEM;
2415         }
2416 
2417         /* ring buffer internal formats */
2418         trace_create_file("header_page", 0444, d_events,
2419                           ring_buffer_print_page_header,
2420                           &ftrace_show_header_fops);
2421 
2422         trace_create_file("header_event", 0444, d_events,
2423                           ring_buffer_print_entry_header,
2424                           &ftrace_show_header_fops);
2425 
2426         trace_create_file("enable", 0644, d_events,
2427                           tr, &ftrace_tr_enable_fops);
2428 
2429         tr->event_dir = d_events;
2430 
2431         return 0;
2432 }
2433 
2434 /**
2435  * event_trace_add_tracer - add a instance of a trace_array to events
2436  * @parent: The parent dentry to place the files/directories for events in
2437  * @tr: The trace array associated with these events
2438  *
2439  * When a new instance is created, it needs to set up its events
2440  * directory, as well as other files associated with events. It also
2441  * creates the event hierachry in the @parent/events directory.
2442  *
2443  * Returns 0 on success.
2444  */
2445 int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
2446 {
2447         int ret;
2448 
2449         mutex_lock(&event_mutex);
2450 
2451         ret = create_event_toplevel_files(parent, tr);
2452         if (ret)
2453                 goto out_unlock;
2454 
2455         down_write(&trace_event_sem);
2456         __trace_add_event_dirs(tr);
2457         up_write(&trace_event_sem);
2458 
2459  out_unlock:
2460         mutex_unlock(&event_mutex);
2461 
2462         return ret;
2463 }
2464 
2465 /*
2466  * The top trace array already had its file descriptors created.
2467  * Now the files themselves need to be created.
2468  */
2469 static __init int
2470 early_event_add_tracer(struct dentry *parent, struct trace_array *tr)
2471 {
2472         int ret;
2473 
2474         mutex_lock(&event_mutex);
2475 
2476         ret = create_event_toplevel_files(parent, tr);
2477         if (ret)
2478                 goto out_unlock;
2479 
2480         down_write(&trace_event_sem);
2481         __trace_early_add_event_dirs(tr);
2482         up_write(&trace_event_sem);
2483 
2484  out_unlock:
2485         mutex_unlock(&event_mutex);
2486 
2487         return ret;
2488 }
2489 
2490 int event_trace_del_tracer(struct trace_array *tr)
2491 {
2492         mutex_lock(&event_mutex);
2493 
2494         /* Disable any running events */
2495         __ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);
2496 
2497         down_write(&trace_event_sem);
2498         __trace_remove_event_dirs(tr);
2499         debugfs_remove_recursive(tr->event_dir);
2500         up_write(&trace_event_sem);
2501 
2502         tr->event_dir = NULL;
2503 
2504         mutex_unlock(&event_mutex);
2505 
2506         return 0;
2507 }
2508 
2509 static __init int event_trace_memsetup(void)
2510 {
2511         field_cachep = KMEM_CACHE(ftrace_event_field, SLAB_PANIC);
2512         file_cachep = KMEM_CACHE(ftrace_event_file, SLAB_PANIC);
2513         return 0;
2514 }
2515 
2516 static __init int event_trace_enable(void)
2517 {
2518         struct trace_array *tr = top_trace_array();
2519         struct ftrace_event_call **iter, *call;
2520         char *buf = bootup_event_buf;
2521         char *token;
2522         int ret;
2523 
2524         for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {
2525 
2526                 call = *iter;
2527                 ret = event_init(call);
2528                 if (!ret)
2529                         list_add(&call->list, &ftrace_events);
2530         }
2531 
2532         /*
2533          * We need the top trace array to have a working set of trace
2534          * points at early init, before the debug files and directories
2535          * are created. Create the file entries now, and attach them
2536          * to the actual file dentries later.
2537          */
2538         __trace_early_add_events(tr);
2539 
2540         while (true) {
2541                 token = strsep(&buf, ",");
2542 
2543                 if (!token)
2544                         break;
2545                 if (!*token)
2546                         continue;
2547 
2548                 ret = ftrace_set_clr_event(tr, token, 1);
2549                 if (ret)
2550                         pr_warn("Failed to enable trace event: %s\n", token);
2551         }
2552 
2553         trace_printk_start_comm();
2554 
2555         register_event_cmds();
2556 
2557         return 0;
2558 }
2559 
2560 static __init int event_trace_init(void)
2561 {
2562         struct trace_array *tr;
2563         struct dentry *d_tracer;
2564         struct dentry *entry;
2565         int ret;
2566 
2567         tr = top_trace_array();
2568 
2569         d_tracer = tracing_init_dentry();
2570         if (!d_tracer)
2571                 return 0;
2572 
2573         entry = debugfs_create_file("available_events", 0444, d_tracer,
2574                                     tr, &ftrace_avail_fops);
2575         if (!entry)
2576                 pr_warning("Could not create debugfs "
2577                            "'available_events' entry\n");
2578 
2579         if (trace_define_common_fields())
2580                 pr_warning("tracing: Failed to allocate common fields");
2581 
2582         ret = early_event_add_tracer(d_tracer, tr);
2583         if (ret)
2584                 return ret;
2585 
2586         ret = register_module_notifier(&trace_module_nb);
2587         if (ret)
2588                 pr_warning("Failed to register trace events module notifier\n");
2589 
2590         return 0;
2591 }
2592 early_initcall(event_trace_memsetup);
2593 core_initcall(event_trace_enable);
2594 fs_initcall(event_trace_init);
2595 
2596 #ifdef CONFIG_FTRACE_STARTUP_TEST
2597 
2598 static DEFINE_SPINLOCK(test_spinlock);
2599 static DEFINE_SPINLOCK(test_spinlock_irq);
2600 static DEFINE_MUTEX(test_mutex);
2601 
2602 static __init void test_work(struct work_struct *dummy)
2603 {
2604         spin_lock(&test_spinlock);
2605         spin_lock_irq(&test_spinlock_irq);
2606         udelay(1);
2607         spin_unlock_irq(&test_spinlock_irq);
2608         spin_unlock(&test_spinlock);
2609 
2610         mutex_lock(&test_mutex);
2611         msleep(1);
2612         mutex_unlock(&test_mutex);
2613 }
2614 
2615 static __init int event_test_thread(void *unused)
2616 {
2617         void *test_malloc;
2618 
2619         test_malloc = kmalloc(1234, GFP_KERNEL);
2620         if (!test_malloc)
2621                 pr_info("failed to kmalloc\n");
2622 
2623         schedule_on_each_cpu(test_work);
2624 
2625         kfree(test_malloc);
2626 
2627         set_current_state(TASK_INTERRUPTIBLE);
2628         while (!kthread_should_stop())
2629                 schedule();
2630 
2631         return 0;
2632 }
2633 
2634 /*
2635  * Do various things that may trigger events.
2636  */
2637 static __init void event_test_stuff(void)
2638 {
2639         struct task_struct *test_thread;
2640 
2641         test_thread = kthread_run(event_test_thread, NULL, "test-events");
2642         msleep(1);
2643         kthread_stop(test_thread);
2644 }
2645 
2646 /*
2647  * For every trace event defined, we will test each trace point separately,
2648  * and then by groups, and finally all trace points.
2649  */
2650 static __init void event_trace_self_tests(void)
2651 {
2652         struct ftrace_subsystem_dir *dir;
2653         struct ftrace_event_file *file;
2654         struct ftrace_event_call *call;
2655         struct event_subsystem *system;
2656         struct trace_array *tr;
2657         int ret;
2658 
2659         tr = top_trace_array();
2660 
2661         pr_info("Running tests on trace events:\n");
2662 
2663         list_for_each_entry(file, &tr->events, list) {
2664 
2665                 call = file->event_call;
2666 
2667                 /* Only test those that have a probe */
2668                 if (!call->class || !call->class->probe)
2669                         continue;
2670 
2671 /*
2672  * Testing syscall events here is pretty useless, but
2673  * we still do it if configured. But this is time consuming.
2674  * What we really need is a user thread to perform the
2675  * syscalls as we test.
2676  */
2677 #ifndef CONFIG_EVENT_TRACE_TEST_SYSCALLS
2678                 if (call->class->system &&
2679                     strcmp(call->class->system, "syscalls") == 0)
2680                         continue;
2681 #endif
2682 
2683                 pr_info("Testing event %s: ", call->name);
2684 
2685                 /*
2686                  * If an event is already enabled, someone is using
2687                  * it and the self test should not be on.
2688                  */
2689                 if (file->flags & FTRACE_EVENT_FL_ENABLED) {
2690                         pr_warning("Enabled event during self test!\n");
2691                         WARN_ON_ONCE(1);
2692                         continue;
2693                 }
2694 
2695                 ftrace_event_enable_disable(file, 1);
2696                 event_test_stuff();
2697                 ftrace_event_enable_disable(file, 0);
2698 
2699                 pr_cont("OK\n");
2700         }
2701 
2702         /* Now test at the sub system level */
2703 
2704         pr_info("Running tests on trace event systems:\n");
2705 
2706         list_for_each_entry(dir, &tr->systems, list) {
2707 
2708                 system = dir->subsystem;
2709 
2710                 /* the ftrace system is special, skip it */
2711                 if (strcmp(system->name, "ftrace") == 0)
2712                         continue;
2713 
2714                 pr_info("Testing event system %s: ", system->name);
2715 
2716                 ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);
2717                 if (WARN_ON_ONCE(ret)) {
2718                         pr_warning("error enabling system %s\n",
2719                                    system->name);
2720                         continue;
2721                 }
2722 
2723                 event_test_stuff();
2724 
2725                 ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);
2726                 if (WARN_ON_ONCE(ret)) {
2727                         pr_warning("error disabling system %s\n",
2728                                    system->name);
2729                         continue;
2730                 }
2731 
2732                 pr_cont("OK\n");
2733         }
2734 
2735         /* Test with all events enabled */
2736 
2737         pr_info("Running tests on all trace events:\n");
2738         pr_info("Testing all events: ");
2739 
2740         ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);
2741         if (WARN_ON_ONCE(ret)) {
2742                 pr_warning("error enabling all events\n");
2743                 return;
2744         }
2745 
2746         event_test_stuff();
2747 
2748         /* reset sysname */
2749         ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
2750         if (WARN_ON_ONCE(ret)) {
2751                 pr_warning("error disabling all events\n");
2752                 return;
2753         }
2754 
2755         pr_cont("OK\n");
2756 }
2757 
2758 #ifdef CONFIG_FUNCTION_TRACER
2759 
2760 static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);
2761 
2762 static void
2763 function_test_events_call(unsigned long ip, unsigned long parent_ip,
2764                           struct ftrace_ops *op, struct pt_regs *pt_regs)
2765 {
2766         struct ring_buffer_event *event;
2767         struct ring_buffer *buffer;
2768         struct ftrace_entry *entry;
2769         unsigned long flags;
2770         long disabled;
2771         int cpu;
2772         int pc;
2773 
2774         pc = preempt_count();
2775         preempt_disable_notrace();
2776         cpu = raw_smp_processor_id();
2777         disabled = atomic_inc_return(&per_cpu(ftrace_test_event_disable, cpu));
2778 
2779         if (disabled != 1)
2780                 goto out;
2781 
2782         local_save_flags(flags);
2783 
2784         event = trace_current_buffer_lock_reserve(&buffer,
2785                                                   TRACE_FN, sizeof(*entry),
2786                                                   flags, pc);
2787         if (!event)
2788                 goto out;
2789         entry   = ring_buffer_event_data(event);
2790         entry->ip                       = ip;
2791         entry->parent_ip                = parent_ip;
2792 
2793         trace_buffer_unlock_commit(buffer, event, flags, pc);
2794 
2795  out:
2796         atomic_dec(&per_cpu(ftrace_test_event_disable, cpu));
2797         preempt_enable_notrace();
2798 }
2799 
2800 static struct ftrace_ops trace_ops __initdata  =
2801 {
2802         .func = function_test_events_call,
2803         .flags = FTRACE_OPS_FL_RECURSION_SAFE,
2804 };
2805 
2806 static __init void event_trace_self_test_with_function(void)
2807 {
2808         int ret;
2809         ret = register_ftrace_function(&trace_ops);
2810         if (WARN_ON(ret < 0)) {
2811                 pr_info("Failed to enable function tracer for event tests\n");
2812                 return;
2813         }
2814         pr_info("Running tests again, along with the function tracer\n");
2815         event_trace_self_tests();
2816         unregister_ftrace_function(&trace_ops);
2817 }
2818 #else
2819 static __init void event_trace_self_test_with_function(void)
2820 {
2821 }
2822 #endif
2823 
2824 static __init int event_trace_self_tests_init(void)
2825 {
2826         if (!tracing_selftest_disabled) {
2827                 event_trace_self_tests();
2828                 event_trace_self_test_with_function();
2829         }
2830 
2831         return 0;
2832 }
2833 
2834 late_initcall(event_trace_self_tests_init);
2835 
2836 #endif
2837 

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