1. 根目录:
2. kernel
3. trace
4. trace_output.h

#ifndef __TRACE_EVENTS_H
#define __TRACE_EVENTS_H

#include <linux/trace_seq.h>
#include "trace.h"

extern enum print_line_t
trace_print_bprintk_msg_only(struct trace_iterator *iter);
extern enum print_line_t
trace_print_printk_msg_only(struct trace_iterator *iter);

extern int
seq_print_ip_sym(struct trace_seq *s, unsigned long ip,
		unsigned long sym_flags);
extern int seq_print_userip_objs(const struct userstack_entry *entry,
				 struct trace_seq *s, unsigned long sym_flags);
extern int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
			     unsigned long ip, unsigned long sym_flags);

extern int trace_print_context(struct trace_iterator *iter);
extern int trace_print_lat_context(struct trace_iterator *iter);

extern void trace_event_read_lock(void);
extern void trace_event_read_unlock(void);
extern struct trace_event *ftrace_find_event(int type);

extern enum print_line_t trace_nop_print(struct trace_iterator *iter,
					 int flags, struct trace_event *event);
extern int
trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry);

/* used by module unregistering */
extern int __unregister_ftrace_event(struct trace_event *event);
extern struct rw_semaphore trace_event_mutex;

#define MAX_MEMHEX_BYTES	8
#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)

#define SEQ_PUT_FIELD_RET(s, x)				\
do {							\
	if (!trace_seq_putmem(s, &(x), sizeof(x)))	\
		return TRACE_TYPE_PARTIAL_LINE;		\
} while (0)

#define SEQ_PUT_HEX_FIELD_RET(s, x)			\
do {							\
	BUILD_BUG_ON(sizeof(x) > MAX_MEMHEX_BYTES);	\
	if (!trace_seq_putmem_hex(s, &(x), sizeof(x)))	\
		return TRACE_TYPE_PARTIAL_LINE;		\
} while (0)

#endif