tracing: new format for specialized trace points
[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  * trace_printk entry:
119  */
120 struct print_entry {
121         struct trace_entry      ent;
122         unsigned long           ip;
123         int                     depth;
124         const char              *fmt;
125         u32                     buf[];
126 };
127
128 #define TRACE_OLD_SIZE          88
129
130 struct trace_field_cont {
131         unsigned char           type;
132         /* Temporary till we get rid of this completely */
133         char                    buf[TRACE_OLD_SIZE - 1];
134 };
135
136 struct trace_mmiotrace_rw {
137         struct trace_entry      ent;
138         struct mmiotrace_rw     rw;
139 };
140
141 struct trace_mmiotrace_map {
142         struct trace_entry      ent;
143         struct mmiotrace_map    map;
144 };
145
146 struct trace_boot_call {
147         struct trace_entry      ent;
148         struct boot_trace_call boot_call;
149 };
150
151 struct trace_boot_ret {
152         struct trace_entry      ent;
153         struct boot_trace_ret boot_ret;
154 };
155
156 #define TRACE_FUNC_SIZE 30
157 #define TRACE_FILE_SIZE 20
158 struct trace_branch {
159         struct trace_entry      ent;
160         unsigned                line;
161         char                    func[TRACE_FUNC_SIZE+1];
162         char                    file[TRACE_FILE_SIZE+1];
163         char                    correct;
164 };
165
166 struct hw_branch_entry {
167         struct trace_entry      ent;
168         u64                     from;
169         u64                     to;
170 };
171
172 struct trace_power {
173         struct trace_entry      ent;
174         struct power_trace      state_data;
175 };
176
177 struct kmemtrace_alloc_entry {
178         struct trace_entry      ent;
179         enum kmemtrace_type_id type_id;
180         unsigned long call_site;
181         const void *ptr;
182         size_t bytes_req;
183         size_t bytes_alloc;
184         gfp_t gfp_flags;
185         int node;
186 };
187
188 struct kmemtrace_free_entry {
189         struct trace_entry      ent;
190         enum kmemtrace_type_id type_id;
191         unsigned long call_site;
192         const void *ptr;
193 };
194
195 /*
196  * trace_flag_type is an enumeration that holds different
197  * states when a trace occurs. These are:
198  *  IRQS_OFF            - interrupts were disabled
199  *  IRQS_NOSUPPORT      - arch does not support irqs_disabled_flags
200  *  NEED_RESCED         - reschedule is requested
201  *  HARDIRQ             - inside an interrupt handler
202  *  SOFTIRQ             - inside a softirq handler
203  */
204 enum trace_flag_type {
205         TRACE_FLAG_IRQS_OFF             = 0x01,
206         TRACE_FLAG_IRQS_NOSUPPORT       = 0x02,
207         TRACE_FLAG_NEED_RESCHED         = 0x04,
208         TRACE_FLAG_HARDIRQ              = 0x08,
209         TRACE_FLAG_SOFTIRQ              = 0x10,
210 };
211
212 #define TRACE_BUF_SIZE          1024
213
214 /*
215  * The CPU trace array - it consists of thousands of trace entries
216  * plus some other descriptor data: (for example which task started
217  * the trace, etc.)
218  */
219 struct trace_array_cpu {
220         atomic_t                disabled;
221         void                    *buffer_page;   /* ring buffer spare */
222
223         /* these fields get copied into max-trace: */
224         unsigned long           trace_idx;
225         unsigned long           overrun;
226         unsigned long           saved_latency;
227         unsigned long           critical_start;
228         unsigned long           critical_end;
229         unsigned long           critical_sequence;
230         unsigned long           nice;
231         unsigned long           policy;
232         unsigned long           rt_priority;
233         cycle_t                 preempt_timestamp;
234         pid_t                   pid;
235         uid_t                   uid;
236         char                    comm[TASK_COMM_LEN];
237 };
238
239 struct trace_iterator;
240
241 /*
242  * The trace array - an array of per-CPU trace arrays. This is the
243  * highest level data structure that individual tracers deal with.
244  * They have on/off state as well:
245  */
246 struct trace_array {
247         struct ring_buffer      *buffer;
248         unsigned long           entries;
249         int                     cpu;
250         cycle_t                 time_start;
251         struct task_struct      *waiter;
252         struct trace_array_cpu  *data[NR_CPUS];
253 };
254
255 #define FTRACE_CMP_TYPE(var, type) \
256         __builtin_types_compatible_p(typeof(var), type *)
257
258 #undef IF_ASSIGN
259 #define IF_ASSIGN(var, entry, etype, id)                \
260         if (FTRACE_CMP_TYPE(var, etype)) {              \
261                 var = (typeof(var))(entry);             \
262                 WARN_ON(id && (entry)->type != id);     \
263                 break;                                  \
264         }
265
266 /* Will cause compile errors if type is not found. */
267 extern void __ftrace_bad_type(void);
268
269 /*
270  * The trace_assign_type is a verifier that the entry type is
271  * the same as the type being assigned. To add new types simply
272  * add a line with the following format:
273  *
274  * IF_ASSIGN(var, ent, type, id);
275  *
276  *  Where "type" is the trace type that includes the trace_entry
277  *  as the "ent" item. And "id" is the trace identifier that is
278  *  used in the trace_type enum.
279  *
280  *  If the type can have more than one id, then use zero.
281  */
282 #define trace_assign_type(var, ent)                                     \
283         do {                                                            \
284                 IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);     \
285                 IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);        \
286                 IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);   \
287                 IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
288                 IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);   \
289                 IF_ASSIGN(var, ent, struct special_entry, 0);           \
290                 IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,          \
291                           TRACE_MMIO_RW);                               \
292                 IF_ASSIGN(var, ent, struct trace_mmiotrace_map,         \
293                           TRACE_MMIO_MAP);                              \
294                 IF_ASSIGN(var, ent, struct trace_boot_call, TRACE_BOOT_CALL);\
295                 IF_ASSIGN(var, ent, struct trace_boot_ret, TRACE_BOOT_RET);\
296                 IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
297                 IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,      \
298                           TRACE_GRAPH_ENT);             \
299                 IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,      \
300                           TRACE_GRAPH_RET);             \
301                 IF_ASSIGN(var, ent, struct hw_branch_entry, TRACE_HW_BRANCHES);\
302                 IF_ASSIGN(var, ent, struct trace_power, TRACE_POWER); \
303                 IF_ASSIGN(var, ent, struct kmemtrace_alloc_entry,       \
304                           TRACE_KMEM_ALLOC);    \
305                 IF_ASSIGN(var, ent, struct kmemtrace_free_entry,        \
306                           TRACE_KMEM_FREE);     \
307                 __ftrace_bad_type();                                    \
308         } while (0)
309
310 /* Return values for print_line callback */
311 enum print_line_t {
312         TRACE_TYPE_PARTIAL_LINE = 0,    /* Retry after flushing the seq */
313         TRACE_TYPE_HANDLED      = 1,
314         TRACE_TYPE_UNHANDLED    = 2,    /* Relay to other output functions */
315         TRACE_TYPE_NO_CONSUME   = 3     /* Handled but ask to not consume */
316 };
317
318
319 /*
320  * An option specific to a tracer. This is a boolean value.
321  * The bit is the bit index that sets its value on the
322  * flags value in struct tracer_flags.
323  */
324 struct tracer_opt {
325         const char      *name; /* Will appear on the trace_options file */
326         u32             bit; /* Mask assigned in val field in tracer_flags */
327 };
328
329 /*
330  * The set of specific options for a tracer. Your tracer
331  * have to set the initial value of the flags val.
332  */
333 struct tracer_flags {
334         u32                     val;
335         struct tracer_opt       *opts;
336 };
337
338 /* Makes more easy to define a tracer opt */
339 #define TRACER_OPT(s, b)        .name = #s, .bit = b
340
341
342 /**
343  * struct tracer - a specific tracer and its callbacks to interact with debugfs
344  * @name: the name chosen to select it on the available_tracers file
345  * @init: called when one switches to this tracer (echo name > current_tracer)
346  * @reset: called when one switches to another tracer
347  * @start: called when tracing is unpaused (echo 1 > tracing_enabled)
348  * @stop: called when tracing is paused (echo 0 > tracing_enabled)
349  * @open: called when the trace file is opened
350  * @pipe_open: called when the trace_pipe file is opened
351  * @wait_pipe: override how the user waits for traces on trace_pipe
352  * @close: called when the trace file is released
353  * @read: override the default read callback on trace_pipe
354  * @splice_read: override the default splice_read callback on trace_pipe
355  * @selftest: selftest to run on boot (see trace_selftest.c)
356  * @print_headers: override the first lines that describe your columns
357  * @print_line: callback that prints a trace
358  * @set_flag: signals one of your private flags changed (trace_options file)
359  * @flags: your private flags
360  */
361 struct tracer {
362         const char              *name;
363         int                     (*init)(struct trace_array *tr);
364         void                    (*reset)(struct trace_array *tr);
365         void                    (*start)(struct trace_array *tr);
366         void                    (*stop)(struct trace_array *tr);
367         void                    (*open)(struct trace_iterator *iter);
368         void                    (*pipe_open)(struct trace_iterator *iter);
369         void                    (*wait_pipe)(struct trace_iterator *iter);
370         void                    (*close)(struct trace_iterator *iter);
371         ssize_t                 (*read)(struct trace_iterator *iter,
372                                         struct file *filp, char __user *ubuf,
373                                         size_t cnt, loff_t *ppos);
374         ssize_t                 (*splice_read)(struct trace_iterator *iter,
375                                                struct file *filp,
376                                                loff_t *ppos,
377                                                struct pipe_inode_info *pipe,
378                                                size_t len,
379                                                unsigned int flags);
380 #ifdef CONFIG_FTRACE_STARTUP_TEST
381         int                     (*selftest)(struct tracer *trace,
382                                             struct trace_array *tr);
383 #endif
384         void                    (*print_header)(struct seq_file *m);
385         enum print_line_t       (*print_line)(struct trace_iterator *iter);
386         /* If you handled the flag setting, return 0 */
387         int                     (*set_flag)(u32 old_flags, u32 bit, int set);
388         struct tracer           *next;
389         int                     print_max;
390         struct tracer_flags     *flags;
391         struct tracer_stat      *stats;
392 };
393
394 struct trace_seq {
395         unsigned char           buffer[PAGE_SIZE];
396         unsigned int            len;
397         unsigned int            readpos;
398 };
399
400 static inline void
401 trace_seq_init(struct trace_seq *s)
402 {
403         s->len = 0;
404         s->readpos = 0;
405 }
406
407
408 #define TRACE_PIPE_ALL_CPU      -1
409
410 /*
411  * Trace iterator - used by printout routines who present trace
412  * results to users and which routines might sleep, etc:
413  */
414 struct trace_iterator {
415         struct trace_array      *tr;
416         struct tracer           *trace;
417         void                    *private;
418         int                     cpu_file;
419         struct mutex            mutex;
420         struct ring_buffer_iter *buffer_iter[NR_CPUS];
421
422         /* The below is zeroed out in pipe_read */
423         struct trace_seq        seq;
424         struct trace_entry      *ent;
425         int                     cpu;
426         u64                     ts;
427
428         unsigned long           iter_flags;
429         loff_t                  pos;
430         long                    idx;
431
432         cpumask_var_t           started;
433 };
434
435 int tracer_init(struct tracer *t, struct trace_array *tr);
436 int tracing_is_enabled(void);
437 void trace_wake_up(void);
438 void tracing_reset(struct trace_array *tr, int cpu);
439 void tracing_reset_online_cpus(struct trace_array *tr);
440 int tracing_open_generic(struct inode *inode, struct file *filp);
441 struct dentry *tracing_init_dentry(void);
442 void init_tracer_sysprof_debugfs(struct dentry *d_tracer);
443
444 struct ring_buffer_event;
445
446 struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
447                                                     unsigned char type,
448                                                     unsigned long len,
449                                                     unsigned long flags,
450                                                     int pc);
451 void trace_buffer_unlock_commit(struct trace_array *tr,
452                                 struct ring_buffer_event *event,
453                                 unsigned long flags, int pc);
454
455 struct ring_buffer_event *
456 trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
457                                   unsigned long flags, int pc);
458 void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
459                                         unsigned long flags, int pc);
460
461 struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
462                                                 struct trace_array_cpu *data);
463
464 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
465                                           int *ent_cpu, u64 *ent_ts);
466
467 void tracing_generic_entry_update(struct trace_entry *entry,
468                                   unsigned long flags,
469                                   int pc);
470
471 void default_wait_pipe(struct trace_iterator *iter);
472 void poll_wait_pipe(struct trace_iterator *iter);
473
474 void ftrace(struct trace_array *tr,
475                             struct trace_array_cpu *data,
476                             unsigned long ip,
477                             unsigned long parent_ip,
478                             unsigned long flags, int pc);
479 void tracing_sched_switch_trace(struct trace_array *tr,
480                                 struct task_struct *prev,
481                                 struct task_struct *next,
482                                 unsigned long flags, int pc);
483 void tracing_record_cmdline(struct task_struct *tsk);
484
485 void tracing_sched_wakeup_trace(struct trace_array *tr,
486                                 struct task_struct *wakee,
487                                 struct task_struct *cur,
488                                 unsigned long flags, int pc);
489 void trace_special(struct trace_array *tr,
490                    struct trace_array_cpu *data,
491                    unsigned long arg1,
492                    unsigned long arg2,
493                    unsigned long arg3, int pc);
494 void trace_function(struct trace_array *tr,
495                     unsigned long ip,
496                     unsigned long parent_ip,
497                     unsigned long flags, int pc);
498
499 void trace_graph_return(struct ftrace_graph_ret *trace);
500 int trace_graph_entry(struct ftrace_graph_ent *trace);
501
502 void tracing_start_cmdline_record(void);
503 void tracing_stop_cmdline_record(void);
504 void tracing_sched_switch_assign_trace(struct trace_array *tr);
505 void tracing_stop_sched_switch_record(void);
506 void tracing_start_sched_switch_record(void);
507 int register_tracer(struct tracer *type);
508 void unregister_tracer(struct tracer *type);
509
510 extern unsigned long nsecs_to_usecs(unsigned long nsecs);
511
512 extern unsigned long tracing_max_latency;
513 extern unsigned long tracing_thresh;
514
515 void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
516 void update_max_tr_single(struct trace_array *tr,
517                           struct task_struct *tsk, int cpu);
518
519 void __trace_stack(struct trace_array *tr,
520                    unsigned long flags,
521                    int skip, int pc);
522
523 extern cycle_t ftrace_now(int cpu);
524
525 #ifdef CONFIG_CONTEXT_SWITCH_TRACER
526 typedef void
527 (*tracer_switch_func_t)(void *private,
528                         void *__rq,
529                         struct task_struct *prev,
530                         struct task_struct *next);
531
532 struct tracer_switch_ops {
533         tracer_switch_func_t            func;
534         void                            *private;
535         struct tracer_switch_ops        *next;
536 };
537 #endif /* CONFIG_CONTEXT_SWITCH_TRACER */
538
539 extern char *trace_find_cmdline(int pid);
540
541 #ifdef CONFIG_DYNAMIC_FTRACE
542 extern unsigned long ftrace_update_tot_cnt;
543 #define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
544 extern int DYN_FTRACE_TEST_NAME(void);
545 #endif
546
547 #ifdef CONFIG_FTRACE_STARTUP_TEST
548 extern int trace_selftest_startup_function(struct tracer *trace,
549                                            struct trace_array *tr);
550 extern int trace_selftest_startup_function_graph(struct tracer *trace,
551                                                  struct trace_array *tr);
552 extern int trace_selftest_startup_irqsoff(struct tracer *trace,
553                                           struct trace_array *tr);
554 extern int trace_selftest_startup_preemptoff(struct tracer *trace,
555                                              struct trace_array *tr);
556 extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
557                                                  struct trace_array *tr);
558 extern int trace_selftest_startup_wakeup(struct tracer *trace,
559                                          struct trace_array *tr);
560 extern int trace_selftest_startup_nop(struct tracer *trace,
561                                          struct trace_array *tr);
562 extern int trace_selftest_startup_sched_switch(struct tracer *trace,
563                                                struct trace_array *tr);
564 extern int trace_selftest_startup_sysprof(struct tracer *trace,
565                                                struct trace_array *tr);
566 extern int trace_selftest_startup_branch(struct tracer *trace,
567                                          struct trace_array *tr);
568 #endif /* CONFIG_FTRACE_STARTUP_TEST */
569
570 extern void *head_page(struct trace_array_cpu *data);
571 extern long ns2usecs(cycle_t nsec);
572 extern int
573 trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args);
574
575 extern unsigned long trace_flags;
576
577 /* Standard output formatting function used for function return traces */
578 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
579 extern enum print_line_t print_graph_function(struct trace_iterator *iter);
580
581 #ifdef CONFIG_DYNAMIC_FTRACE
582 /* TODO: make this variable */
583 #define FTRACE_GRAPH_MAX_FUNCS          32
584 extern int ftrace_graph_count;
585 extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS];
586
587 static inline int ftrace_graph_addr(unsigned long addr)
588 {
589         int i;
590
591         if (!ftrace_graph_count || test_tsk_trace_graph(current))
592                 return 1;
593
594         for (i = 0; i < ftrace_graph_count; i++) {
595                 if (addr == ftrace_graph_funcs[i])
596                         return 1;
597         }
598
599         return 0;
600 }
601 #else
602 static inline int ftrace_trace_addr(unsigned long addr)
603 {
604         return 1;
605 }
606 static inline int ftrace_graph_addr(unsigned long addr)
607 {
608         return 1;
609 }
610 #endif /* CONFIG_DYNAMIC_FTRACE */
611
612 #else /* CONFIG_FUNCTION_GRAPH_TRACER */
613 static inline enum print_line_t
614 print_graph_function(struct trace_iterator *iter)
615 {
616         return TRACE_TYPE_UNHANDLED;
617 }
618 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
619
620 extern struct pid *ftrace_pid_trace;
621
622 static inline int ftrace_trace_task(struct task_struct *task)
623 {
624         if (!ftrace_pid_trace)
625                 return 1;
626
627         return test_tsk_trace_trace(task);
628 }
629
630 /*
631  * trace_iterator_flags is an enumeration that defines bit
632  * positions into trace_flags that controls the output.
633  *
634  * NOTE: These bits must match the trace_options array in
635  *       trace.c.
636  */
637 enum trace_iterator_flags {
638         TRACE_ITER_PRINT_PARENT         = 0x01,
639         TRACE_ITER_SYM_OFFSET           = 0x02,
640         TRACE_ITER_SYM_ADDR             = 0x04,
641         TRACE_ITER_VERBOSE              = 0x08,
642         TRACE_ITER_RAW                  = 0x10,
643         TRACE_ITER_HEX                  = 0x20,
644         TRACE_ITER_BIN                  = 0x40,
645         TRACE_ITER_BLOCK                = 0x80,
646         TRACE_ITER_STACKTRACE           = 0x100,
647         TRACE_ITER_SCHED_TREE           = 0x200,
648         TRACE_ITER_PRINTK               = 0x400,
649         TRACE_ITER_PREEMPTONLY          = 0x800,
650         TRACE_ITER_BRANCH               = 0x1000,
651         TRACE_ITER_ANNOTATE             = 0x2000,
652         TRACE_ITER_USERSTACKTRACE       = 0x4000,
653         TRACE_ITER_SYM_USEROBJ          = 0x8000,
654         TRACE_ITER_PRINTK_MSGONLY       = 0x10000,
655         TRACE_ITER_CONTEXT_INFO         = 0x20000, /* Print pid/cpu/time */
656         TRACE_ITER_LATENCY_FMT          = 0x40000,
657 };
658
659 /*
660  * TRACE_ITER_SYM_MASK masks the options in trace_flags that
661  * control the output of kernel symbols.
662  */
663 #define TRACE_ITER_SYM_MASK \
664         (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
665
666 extern struct tracer nop_trace;
667
668 /**
669  * ftrace_preempt_disable - disable preemption scheduler safe
670  *
671  * When tracing can happen inside the scheduler, there exists
672  * cases that the tracing might happen before the need_resched
673  * flag is checked. If this happens and the tracer calls
674  * preempt_enable (after a disable), a schedule might take place
675  * causing an infinite recursion.
676  *
677  * To prevent this, we read the need_resched flag before
678  * disabling preemption. When we want to enable preemption we
679  * check the flag, if it is set, then we call preempt_enable_no_resched.
680  * Otherwise, we call preempt_enable.
681  *
682  * The rational for doing the above is that if need_resched is set
683  * and we have yet to reschedule, we are either in an atomic location
684  * (where we do not need to check for scheduling) or we are inside
685  * the scheduler and do not want to resched.
686  */
687 static inline int ftrace_preempt_disable(void)
688 {
689         int resched;
690
691         resched = need_resched();
692         preempt_disable_notrace();
693
694         return resched;
695 }
696
697 /**
698  * ftrace_preempt_enable - enable preemption scheduler safe
699  * @resched: the return value from ftrace_preempt_disable
700  *
701  * This is a scheduler safe way to enable preemption and not miss
702  * any preemption checks. The disabled saved the state of preemption.
703  * If resched is set, then we are either inside an atomic or
704  * are inside the scheduler (we would have already scheduled
705  * otherwise). In this case, we do not want to call normal
706  * preempt_enable, but preempt_enable_no_resched instead.
707  */
708 static inline void ftrace_preempt_enable(int resched)
709 {
710         if (resched)
711                 preempt_enable_no_resched_notrace();
712         else
713                 preempt_enable_notrace();
714 }
715
716 #ifdef CONFIG_BRANCH_TRACER
717 extern int enable_branch_tracing(struct trace_array *tr);
718 extern void disable_branch_tracing(void);
719 static inline int trace_branch_enable(struct trace_array *tr)
720 {
721         if (trace_flags & TRACE_ITER_BRANCH)
722                 return enable_branch_tracing(tr);
723         return 0;
724 }
725 static inline void trace_branch_disable(void)
726 {
727         /* due to races, always disable */
728         disable_branch_tracing();
729 }
730 #else
731 static inline int trace_branch_enable(struct trace_array *tr)
732 {
733         return 0;
734 }
735 static inline void trace_branch_disable(void)
736 {
737 }
738 #endif /* CONFIG_BRANCH_TRACER */
739
740 /* trace event type bit fields, not numeric */
741 enum {
742         TRACE_EVENT_TYPE_PRINTF         = 1,
743         TRACE_EVENT_TYPE_RAW            = 2,
744 };
745
746 struct ftrace_event_call {
747         char            *name;
748         char            *system;
749         struct dentry   *dir;
750         int             enabled;
751         int             (*regfunc)(void);
752         void            (*unregfunc)(void);
753         int             id;
754         int             (*raw_init)(void);
755         int             (*show_format)(struct trace_seq *s);
756 };
757
758 void event_trace_printk(unsigned long ip, const char *fmt, ...);
759 extern struct ftrace_event_call __start_ftrace_events[];
760 extern struct ftrace_event_call __stop_ftrace_events[];
761
762 #endif /* _LINUX_KERNEL_TRACE_H */