tracing: make trace_seq_reset global and rename to trace_seq_init
[linux-2.6.git] / kernel / trace / trace.h
1 #ifndef _LINUX_KERNEL_TRACE_H
2 #define _LINUX_KERNEL_TRACE_H
3
4 #include <linux/fs.h>
5 #include <asm/atomic.h>
6 #include <linux/sched.h>
7 #include <linux/clocksource.h>
8 #include <linux/ring_buffer.h>
9 #include <linux/mmiotrace.h>
10 #include <linux/ftrace.h>
11 #include <trace/boot.h>
12 #include <trace/kmemtrace.h>
13 #include <trace/power.h>
14
15 enum trace_type {
16         __TRACE_FIRST_TYPE = 0,
17
18         TRACE_FN,
19         TRACE_CTX,
20         TRACE_WAKE,
21         TRACE_STACK,
22         TRACE_PRINT,
23         TRACE_SPECIAL,
24         TRACE_MMIO_RW,
25         TRACE_MMIO_MAP,
26         TRACE_BRANCH,
27         TRACE_BOOT_CALL,
28         TRACE_BOOT_RET,
29         TRACE_GRAPH_RET,
30         TRACE_GRAPH_ENT,
31         TRACE_USER_STACK,
32         TRACE_HW_BRANCHES,
33         TRACE_KMEM_ALLOC,
34         TRACE_KMEM_FREE,
35         TRACE_POWER,
36         TRACE_BLK,
37
38         __TRACE_LAST_TYPE,
39 };
40
41 /*
42  * The trace entry - the most basic unit of tracing. This is what
43  * is printed in the end as a single line in the trace output, such as:
44  *
45  *     bash-15816 [01]   235.197585: idle_cpu <- irq_enter
46  */
47 struct trace_entry {
48         unsigned char           type;
49         unsigned char           flags;
50         unsigned char           preempt_count;
51         int                     pid;
52         int                     tgid;
53 };
54
55 /*
56  * Function trace entry - function address and parent function addres:
57  */
58 struct ftrace_entry {
59         struct trace_entry      ent;
60         unsigned long           ip;
61         unsigned long           parent_ip;
62 };
63
64 /* Function call entry */
65 struct ftrace_graph_ent_entry {
66         struct trace_entry              ent;
67         struct ftrace_graph_ent         graph_ent;
68 };
69
70 /* Function return entry */
71 struct ftrace_graph_ret_entry {
72         struct trace_entry              ent;
73         struct ftrace_graph_ret         ret;
74 };
75 extern struct tracer boot_tracer;
76
77 /*
78  * Context switch trace entry - which task (and prio) we switched from/to:
79  */
80 struct ctx_switch_entry {
81         struct trace_entry      ent;
82         unsigned int            prev_pid;
83         unsigned char           prev_prio;
84         unsigned char           prev_state;
85         unsigned int            next_pid;
86         unsigned char           next_prio;
87         unsigned char           next_state;
88         unsigned int            next_cpu;
89 };
90
91 /*
92  * Special (free-form) trace entry:
93  */
94 struct special_entry {
95         struct trace_entry      ent;
96         unsigned long           arg1;
97         unsigned long           arg2;
98         unsigned long           arg3;
99 };
100
101 /*
102  * Stack-trace entry:
103  */
104
105 #define FTRACE_STACK_ENTRIES    8
106
107 struct stack_entry {
108         struct trace_entry      ent;
109         unsigned long           caller[FTRACE_STACK_ENTRIES];
110 };
111
112 struct userstack_entry {
113         struct trace_entry      ent;
114         unsigned long           caller[FTRACE_STACK_ENTRIES];
115 };
116
117 /*
118  * ftrace_printk entry:
119  */
120 struct print_entry {
121         struct trace_entry      ent;
122         unsigned long           ip;
123         int                     depth;
124         char                    buf[];
125 };
126
127 #define TRACE_OLD_SIZE          88
128
129 struct trace_field_cont {
130         unsigned char           type;
131         /* Temporary till we get rid of this completely */
132         char                    buf[TRACE_OLD_SIZE - 1];
133 };
134
135 struct trace_mmiotrace_rw {
136         struct trace_entry      ent;
137         struct mmiotrace_rw     rw;
138 };
139
140 struct trace_mmiotrace_map {
141         struct trace_entry      ent;
142         struct mmiotrace_map    map;
143 };
144
145 struct trace_boot_call {
146         struct trace_entry      ent;
147         struct boot_trace_call boot_call;
148 };
149
150 struct trace_boot_ret {
151         struct trace_entry      ent;
152         struct boot_trace_ret boot_ret;
153 };
154
155 #define TRACE_FUNC_SIZE 30
156 #define TRACE_FILE_SIZE 20
157 struct trace_branch {
158         struct trace_entry      ent;
159         unsigned                line;
160         char                    func[TRACE_FUNC_SIZE+1];
161         char                    file[TRACE_FILE_SIZE+1];
162         char                    correct;
163 };
164
165 struct hw_branch_entry {
166         struct trace_entry      ent;
167         u64                     from;
168         u64                     to;
169 };
170
171 struct trace_power {
172         struct trace_entry      ent;
173         struct power_trace      state_data;
174 };
175
176 struct kmemtrace_alloc_entry {
177         struct trace_entry      ent;
178         enum kmemtrace_type_id type_id;
179         unsigned long call_site;
180         const void *ptr;
181         size_t bytes_req;
182         size_t bytes_alloc;
183         gfp_t gfp_flags;
184         int node;
185 };
186
187 struct kmemtrace_free_entry {
188         struct trace_entry      ent;
189         enum kmemtrace_type_id type_id;
190         unsigned long call_site;
191         const void *ptr;
192 };
193
194 /*
195  * trace_flag_type is an enumeration that holds different
196  * states when a trace occurs. These are:
197  *  IRQS_OFF            - interrupts were disabled
198  *  IRQS_NOSUPPORT      - arch does not support irqs_disabled_flags
199  *  NEED_RESCED         - reschedule is requested
200  *  HARDIRQ             - inside an interrupt handler
201  *  SOFTIRQ             - inside a softirq handler
202  */
203 enum trace_flag_type {
204         TRACE_FLAG_IRQS_OFF             = 0x01,
205         TRACE_FLAG_IRQS_NOSUPPORT       = 0x02,
206         TRACE_FLAG_NEED_RESCHED         = 0x04,
207         TRACE_FLAG_HARDIRQ              = 0x08,
208         TRACE_FLAG_SOFTIRQ              = 0x10,
209 };
210
211 #define TRACE_BUF_SIZE          1024
212
213 /*
214  * The CPU trace array - it consists of thousands of trace entries
215  * plus some other descriptor data: (for example which task started
216  * the trace, etc.)
217  */
218 struct trace_array_cpu {
219         atomic_t                disabled;
220
221         /* these fields get copied into max-trace: */
222         unsigned long           trace_idx;
223         unsigned long           overrun;
224         unsigned long           saved_latency;
225         unsigned long           critical_start;
226         unsigned long           critical_end;
227         unsigned long           critical_sequence;
228         unsigned long           nice;
229         unsigned long           policy;
230         unsigned long           rt_priority;
231         cycle_t                 preempt_timestamp;
232         pid_t                   pid;
233         uid_t                   uid;
234         char                    comm[TASK_COMM_LEN];
235 };
236
237 struct trace_iterator;
238
239 /*
240  * The trace array - an array of per-CPU trace arrays. This is the
241  * highest level data structure that individual tracers deal with.
242  * They have on/off state as well:
243  */
244 struct trace_array {
245         struct ring_buffer      *buffer;
246         unsigned long           entries;
247         int                     cpu;
248         cycle_t                 time_start;
249         struct task_struct      *waiter;
250         struct trace_array_cpu  *data[NR_CPUS];
251 };
252
253 #define FTRACE_CMP_TYPE(var, type) \
254         __builtin_types_compatible_p(typeof(var), type *)
255
256 #undef IF_ASSIGN
257 #define IF_ASSIGN(var, entry, etype, id)                \
258         if (FTRACE_CMP_TYPE(var, etype)) {              \
259                 var = (typeof(var))(entry);             \
260                 WARN_ON(id && (entry)->type != id);     \
261                 break;                                  \
262         }
263
264 /* Will cause compile errors if type is not found. */
265 extern void __ftrace_bad_type(void);
266
267 /*
268  * The trace_assign_type is a verifier that the entry type is
269  * the same as the type being assigned. To add new types simply
270  * add a line with the following format:
271  *
272  * IF_ASSIGN(var, ent, type, id);
273  *
274  *  Where "type" is the trace type that includes the trace_entry
275  *  as the "ent" item. And "id" is the trace identifier that is
276  *  used in the trace_type enum.
277  *
278  *  If the type can have more than one id, then use zero.
279  */
280 #define trace_assign_type(var, ent)                                     \
281         do {                                                            \
282                 IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);     \
283                 IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);        \
284                 IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);   \
285                 IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
286                 IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);   \
287                 IF_ASSIGN(var, ent, struct special_entry, 0);           \
288                 IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,          \
289                           TRACE_MMIO_RW);                               \
290                 IF_ASSIGN(var, ent, struct trace_mmiotrace_map,         \
291                           TRACE_MMIO_MAP);                              \
292                 IF_ASSIGN(var, ent, struct trace_boot_call, TRACE_BOOT_CALL);\
293                 IF_ASSIGN(var, ent, struct trace_boot_ret, TRACE_BOOT_RET);\
294                 IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
295                 IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,      \
296                           TRACE_GRAPH_ENT);             \
297                 IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,      \
298                           TRACE_GRAPH_RET);             \
299                 IF_ASSIGN(var, ent, struct hw_branch_entry, TRACE_HW_BRANCHES);\
300                 IF_ASSIGN(var, ent, struct trace_power, TRACE_POWER); \
301                 IF_ASSIGN(var, ent, struct kmemtrace_alloc_entry,       \
302                           TRACE_KMEM_ALLOC);    \
303                 IF_ASSIGN(var, ent, struct kmemtrace_free_entry,        \
304                           TRACE_KMEM_FREE);     \
305                 __ftrace_bad_type();                                    \
306         } while (0)
307
308 /* Return values for print_line callback */
309 enum print_line_t {
310         TRACE_TYPE_PARTIAL_LINE = 0,    /* Retry after flushing the seq */
311         TRACE_TYPE_HANDLED      = 1,
312         TRACE_TYPE_UNHANDLED    = 2,    /* Relay to other output functions */
313         TRACE_TYPE_NO_CONSUME   = 3     /* Handled but ask to not consume */
314 };
315
316
317 /*
318  * An option specific to a tracer. This is a boolean value.
319  * The bit is the bit index that sets its value on the
320  * flags value in struct tracer_flags.
321  */
322 struct tracer_opt {
323         const char      *name; /* Will appear on the trace_options file */
324         u32             bit; /* Mask assigned in val field in tracer_flags */
325 };
326
327 /*
328  * The set of specific options for a tracer. Your tracer
329  * have to set the initial value of the flags val.
330  */
331 struct tracer_flags {
332         u32                     val;
333         struct tracer_opt       *opts;
334 };
335
336 /* Makes more easy to define a tracer opt */
337 #define TRACER_OPT(s, b)        .name = #s, .bit = b
338
339
340 /**
341  * struct tracer - a specific tracer and its callbacks to interact with debugfs
342  * @name: the name chosen to select it on the available_tracers file
343  * @init: called when one switches to this tracer (echo name > current_tracer)
344  * @reset: called when one switches to another tracer
345  * @start: called when tracing is unpaused (echo 1 > tracing_enabled)
346  * @stop: called when tracing is paused (echo 0 > tracing_enabled)
347  * @open: called when the trace file is opened
348  * @pipe_open: called when the trace_pipe file is opened
349  * @wait_pipe: override how the user waits for traces on trace_pipe
350  * @close: called when the trace file is released
351  * @read: override the default read callback on trace_pipe
352  * @splice_read: override the default splice_read callback on trace_pipe
353  * @selftest: selftest to run on boot (see trace_selftest.c)
354  * @print_headers: override the first lines that describe your columns
355  * @print_line: callback that prints a trace
356  * @set_flag: signals one of your private flags changed (trace_options file)
357  * @flags: your private flags
358  */
359 struct tracer {
360         const char              *name;
361         int                     (*init)(struct trace_array *tr);
362         void                    (*reset)(struct trace_array *tr);
363         void                    (*start)(struct trace_array *tr);
364         void                    (*stop)(struct trace_array *tr);
365         void                    (*open)(struct trace_iterator *iter);
366         void                    (*pipe_open)(struct trace_iterator *iter);
367         void                    (*wait_pipe)(struct trace_iterator *iter);
368         void                    (*close)(struct trace_iterator *iter);
369         ssize_t                 (*read)(struct trace_iterator *iter,
370                                         struct file *filp, char __user *ubuf,
371                                         size_t cnt, loff_t *ppos);
372         ssize_t                 (*splice_read)(struct trace_iterator *iter,
373                                                struct file *filp,
374                                                loff_t *ppos,
375                                                struct pipe_inode_info *pipe,
376                                                size_t len,
377                                                unsigned int flags);
378 #ifdef CONFIG_FTRACE_STARTUP_TEST
379         int                     (*selftest)(struct tracer *trace,
380                                             struct trace_array *tr);
381 #endif
382         void                    (*print_header)(struct seq_file *m);
383         enum print_line_t       (*print_line)(struct trace_iterator *iter);
384         /* If you handled the flag setting, return 0 */
385         int                     (*set_flag)(u32 old_flags, u32 bit, int set);
386         struct tracer           *next;
387         int                     print_max;
388         struct tracer_flags     *flags;
389         struct tracer_stat      *stats;
390 };
391
392 struct trace_seq {
393         unsigned char           buffer[PAGE_SIZE];
394         unsigned int            len;
395         unsigned int            readpos;
396 };
397
398 static inline void
399 trace_seq_init(struct trace_seq *s)
400 {
401         s->len = 0;
402         s->readpos = 0;
403 }
404
405
406 #define TRACE_PIPE_ALL_CPU      -1
407
408 /*
409  * Trace iterator - used by printout routines who present trace
410  * results to users and which routines might sleep, etc:
411  */
412 struct trace_iterator {
413         struct trace_array      *tr;
414         struct tracer           *trace;
415         void                    *private;
416         int                     cpu_file;
417         struct mutex            mutex;
418         struct ring_buffer_iter *buffer_iter[NR_CPUS];
419
420         /* The below is zeroed out in pipe_read */
421         struct trace_seq        seq;
422         struct trace_entry      *ent;
423         int                     cpu;
424         u64                     ts;
425
426         unsigned long           iter_flags;
427         loff_t                  pos;
428         long                    idx;
429
430         cpumask_var_t           started;
431 };
432
433 int tracer_init(struct tracer *t, struct trace_array *tr);
434 int tracing_is_enabled(void);
435 void trace_wake_up(void);
436 void tracing_reset(struct trace_array *tr, int cpu);
437 void tracing_reset_online_cpus(struct trace_array *tr);
438 int tracing_open_generic(struct inode *inode, struct file *filp);
439 struct dentry *tracing_init_dentry(void);
440 void init_tracer_sysprof_debugfs(struct dentry *d_tracer);
441
442 struct ring_buffer_event;
443
444 struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
445                                                     unsigned char type,
446                                                     unsigned long len,
447                                                     unsigned long flags,
448                                                     int pc);
449 void trace_buffer_unlock_commit(struct trace_array *tr,
450                                 struct ring_buffer_event *event,
451                                 unsigned long flags, int pc);
452
453 struct ring_buffer_event *
454 trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
455                                   unsigned long flags, int pc);
456 void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
457                                         unsigned long flags, int pc);
458
459 struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
460                                                 struct trace_array_cpu *data);
461
462 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
463                                           int *ent_cpu, u64 *ent_ts);
464
465 void tracing_generic_entry_update(struct trace_entry *entry,
466                                   unsigned long flags,
467                                   int pc);
468
469 void default_wait_pipe(struct trace_iterator *iter);
470 void poll_wait_pipe(struct trace_iterator *iter);
471
472 void ftrace(struct trace_array *tr,
473                             struct trace_array_cpu *data,
474                             unsigned long ip,
475                             unsigned long parent_ip,
476                             unsigned long flags, int pc);
477 void tracing_sched_switch_trace(struct trace_array *tr,
478                                 struct task_struct *prev,
479                                 struct task_struct *next,
480                                 unsigned long flags, int pc);
481 void tracing_record_cmdline(struct task_struct *tsk);
482
483 void tracing_sched_wakeup_trace(struct trace_array *tr,
484                                 struct task_struct *wakee,
485                                 struct task_struct *cur,
486                                 unsigned long flags, int pc);
487 void trace_special(struct trace_array *tr,
488                    struct trace_array_cpu *data,
489                    unsigned long arg1,
490                    unsigned long arg2,
491                    unsigned long arg3, int pc);
492 void trace_function(struct trace_array *tr,
493                     unsigned long ip,
494                     unsigned long parent_ip,
495                     unsigned long flags, int pc);
496
497 void trace_graph_return(struct ftrace_graph_ret *trace);
498 int trace_graph_entry(struct ftrace_graph_ent *trace);
499
500 void tracing_start_cmdline_record(void);
501 void tracing_stop_cmdline_record(void);
502 void tracing_sched_switch_assign_trace(struct trace_array *tr);
503 void tracing_stop_sched_switch_record(void);
504 void tracing_start_sched_switch_record(void);
505 int register_tracer(struct tracer *type);
506 void unregister_tracer(struct tracer *type);
507
508 extern unsigned long nsecs_to_usecs(unsigned long nsecs);
509
510 extern unsigned long tracing_max_latency;
511 extern unsigned long tracing_thresh;
512
513 void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
514 void update_max_tr_single(struct trace_array *tr,
515                           struct task_struct *tsk, int cpu);
516
517 void __trace_stack(struct trace_array *tr,
518                    unsigned long flags,
519                    int skip, int pc);
520
521 extern cycle_t ftrace_now(int cpu);
522
523 #ifdef CONFIG_CONTEXT_SWITCH_TRACER
524 typedef void
525 (*tracer_switch_func_t)(void *private,
526                         void *__rq,
527                         struct task_struct *prev,
528                         struct task_struct *next);
529
530 struct tracer_switch_ops {
531         tracer_switch_func_t            func;
532         void                            *private;
533         struct tracer_switch_ops        *next;
534 };
535 #endif /* CONFIG_CONTEXT_SWITCH_TRACER */
536
537 extern char *trace_find_cmdline(int pid);
538
539 #ifdef CONFIG_DYNAMIC_FTRACE
540 extern unsigned long ftrace_update_tot_cnt;
541 #define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
542 extern int DYN_FTRACE_TEST_NAME(void);
543 #endif
544
545 #ifdef CONFIG_FTRACE_STARTUP_TEST
546 extern int trace_selftest_startup_function(struct tracer *trace,
547                                            struct trace_array *tr);
548 extern int trace_selftest_startup_function_graph(struct tracer *trace,
549                                                  struct trace_array *tr);
550 extern int trace_selftest_startup_irqsoff(struct tracer *trace,
551                                           struct trace_array *tr);
552 extern int trace_selftest_startup_preemptoff(struct tracer *trace,
553                                              struct trace_array *tr);
554 extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
555                                                  struct trace_array *tr);
556 extern int trace_selftest_startup_wakeup(struct tracer *trace,
557                                          struct trace_array *tr);
558 extern int trace_selftest_startup_nop(struct tracer *trace,
559                                          struct trace_array *tr);
560 extern int trace_selftest_startup_sched_switch(struct tracer *trace,
561                                                struct trace_array *tr);
562 extern int trace_selftest_startup_sysprof(struct tracer *trace,
563                                                struct trace_array *tr);
564 extern int trace_selftest_startup_branch(struct tracer *trace,
565                                          struct trace_array *tr);
566 #endif /* CONFIG_FTRACE_STARTUP_TEST */
567
568 extern void *head_page(struct trace_array_cpu *data);
569 extern long ns2usecs(cycle_t nsec);
570 extern int
571 trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args);
572
573 extern unsigned long trace_flags;
574
575 /* Standard output formatting function used for function return traces */
576 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
577 extern enum print_line_t print_graph_function(struct trace_iterator *iter);
578
579 #ifdef CONFIG_DYNAMIC_FTRACE
580 /* TODO: make this variable */
581 #define FTRACE_GRAPH_MAX_FUNCS          32
582 extern int ftrace_graph_count;
583 extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
584
585 static inline int ftrace_graph_addr(unsigned long addr)
586 {
587         int i;
588
589         if (!ftrace_graph_count || test_tsk_trace_graph(current))
590                 return 1;
591
592         for (i = 0; i < ftrace_graph_count; i++) {
593                 if (addr == ftrace_graph_funcs[i])
594                         return 1;
595         }
596
597         return 0;
598 }
599 #else
600 static inline int ftrace_trace_addr(unsigned long addr)
601 {
602         return 1;
603 }
604 static inline int ftrace_graph_addr(unsigned long addr)
605 {
606         return 1;
607 }
608 #endif /* CONFIG_DYNAMIC_FTRACE */
609
610 #else /* CONFIG_FUNCTION_GRAPH_TRACER */
611 static inline enum print_line_t
612 print_graph_function(struct trace_iterator *iter)
613 {
614         return TRACE_TYPE_UNHANDLED;
615 }
616 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
617
618 extern struct pid *ftrace_pid_trace;
619
620 static inline int ftrace_trace_task(struct task_struct *task)
621 {
622         if (!ftrace_pid_trace)
623                 return 1;
624
625         return test_tsk_trace_trace(task);
626 }
627
628 /*
629  * trace_iterator_flags is an enumeration that defines bit
630  * positions into trace_flags that controls the output.
631  *
632  * NOTE: These bits must match the trace_options array in
633  *       trace.c.
634  */
635 enum trace_iterator_flags {
636         TRACE_ITER_PRINT_PARENT         = 0x01,
637         TRACE_ITER_SYM_OFFSET           = 0x02,
638         TRACE_ITER_SYM_ADDR             = 0x04,
639         TRACE_ITER_VERBOSE              = 0x08,
640         TRACE_ITER_RAW                  = 0x10,
641         TRACE_ITER_HEX                  = 0x20,
642         TRACE_ITER_BIN                  = 0x40,
643         TRACE_ITER_BLOCK                = 0x80,
644         TRACE_ITER_STACKTRACE           = 0x100,
645         TRACE_ITER_SCHED_TREE           = 0x200,
646         TRACE_ITER_PRINTK               = 0x400,
647         TRACE_ITER_PREEMPTONLY          = 0x800,
648         TRACE_ITER_BRANCH               = 0x1000,
649         TRACE_ITER_ANNOTATE             = 0x2000,
650         TRACE_ITER_USERSTACKTRACE       = 0x4000,
651         TRACE_ITER_SYM_USEROBJ          = 0x8000,
652         TRACE_ITER_PRINTK_MSGONLY       = 0x10000,
653         TRACE_ITER_CONTEXT_INFO         = 0x20000 /* Print pid/cpu/time */
654 };
655
656 /*
657  * TRACE_ITER_SYM_MASK masks the options in trace_flags that
658  * control the output of kernel symbols.
659  */
660 #define TRACE_ITER_SYM_MASK \
661         (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
662
663 extern struct tracer nop_trace;
664
665 /**
666  * ftrace_preempt_disable - disable preemption scheduler safe
667  *
668  * When tracing can happen inside the scheduler, there exists
669  * cases that the tracing might happen before the need_resched
670  * flag is checked. If this happens and the tracer calls
671  * preempt_enable (after a disable), a schedule might take place
672  * causing an infinite recursion.
673  *
674  * To prevent this, we read the need_resched flag before
675  * disabling preemption. When we want to enable preemption we
676  * check the flag, if it is set, then we call preempt_enable_no_resched.
677  * Otherwise, we call preempt_enable.
678  *
679  * The rational for doing the above is that if need_resched is set
680  * and we have yet to reschedule, we are either in an atomic location
681  * (where we do not need to check for scheduling) or we are inside
682  * the scheduler and do not want to resched.
683  */
684 static inline int ftrace_preempt_disable(void)
685 {
686         int resched;
687
688         resched = need_resched();
689         preempt_disable_notrace();
690
691         return resched;
692 }
693
694 /**
695  * ftrace_preempt_enable - enable preemption scheduler safe
696  * @resched: the return value from ftrace_preempt_disable
697  *
698  * This is a scheduler safe way to enable preemption and not miss
699  * any preemption checks. The disabled saved the state of preemption.
700  * If resched is set, then we are either inside an atomic or
701  * are inside the scheduler (we would have already scheduled
702  * otherwise). In this case, we do not want to call normal
703  * preempt_enable, but preempt_enable_no_resched instead.
704  */
705 static inline void ftrace_preempt_enable(int resched)
706 {
707         if (resched)
708                 preempt_enable_no_resched_notrace();
709         else
710                 preempt_enable_notrace();
711 }
712
713 #ifdef CONFIG_BRANCH_TRACER
714 extern int enable_branch_tracing(struct trace_array *tr);
715 extern void disable_branch_tracing(void);
716 static inline int trace_branch_enable(struct trace_array *tr)
717 {
718         if (trace_flags & TRACE_ITER_BRANCH)
719                 return enable_branch_tracing(tr);
720         return 0;
721 }
722 static inline void trace_branch_disable(void)
723 {
724         /* due to races, always disable */
725         disable_branch_tracing();
726 }
727 #else
728 static inline int trace_branch_enable(struct trace_array *tr)
729 {
730         return 0;
731 }
732 static inline void trace_branch_disable(void)
733 {
734 }
735 #endif /* CONFIG_BRANCH_TRACER */
736
737 /* trace event type bit fields, not numeric */
738 enum {
739         TRACE_EVENT_TYPE_PRINTF         = 1,
740         TRACE_EVENT_TYPE_RAW            = 2,
741 };
742
743 struct ftrace_event_call {
744         char            *name;
745         char            *system;
746         struct dentry   *dir;
747         int             enabled;
748         int             (*regfunc)(void);
749         void            (*unregfunc)(void);
750         int             id;
751         struct dentry   *raw_dir;
752         int             raw_enabled;
753         int             type;
754         int             (*raw_init)(void);
755         int             (*raw_reg)(void);
756         void            (*raw_unreg)(void);
757 };
758
759 void event_trace_printk(unsigned long ip, const char *fmt, ...);
760 extern struct ftrace_event_call __start_ftrace_events[];
761 extern struct ftrace_event_call __stop_ftrace_events[];
762
763 #endif /* _LINUX_KERNEL_TRACE_H */