include/linux/ftrace.h

#ifndef _LINUX_FTRACE_H
#define _LINUX_FTRACE_H

#ifdef CONFIG_FTRACE

#include <linux/linkage.h>

#define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
#define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
#define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))

typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);

struct ftrace_ops {
	ftrace_func_t	  func;
	struct ftrace_ops *next;
};

/*
 * The ftrace_ops must be a static and should also
 * be read_mostly.  These functions do modify read_mostly variables
 * so use them sparely. Never free an ftrace_op or modify the
 * next pointer after it has been registered. Even after unregistering
 * it, the next pointer may still be used internally.
 */
int register_ftrace_function(struct ftrace_ops *ops);
int unregister_ftrace_function(struct ftrace_ops *ops);
void clear_ftrace_function(void);

extern void ftrace_stub(unsigned long a0, unsigned long a1);
extern void mcount(void);

#else /* !CONFIG_FTRACE */
# define register_ftrace_function(ops) do { } while (0)
# define unregister_ftrace_function(ops) do { } while (0)
# define clear_ftrace_function(ops) do { } while (0)
#endif /* CONFIG_FTRACE */
#endif /* _LINUX_FTRACE_H */