ftrace_hook.h

#ifndef _H_FTRACE_HOOK
#define _H_FTRACE_HOOK

/**
 * struct ftrace_hook - describes a single hook to install
 *
 * @name:     name of the function to hook
 *
 * @function: pointer to the function to connect instead
 *
 * @original: pointer to the location where to save a pointer
 *            to the original function
 *
 * @address:  kernel address of the function entry
 *
 * @ops:      ftrace_ops state for this function hook
 *
 * The user should fill in only &name, &hook, &orig fields.
 * Other fields are considered implementation details.
 */
struct ftrace_hook {
	const char *name;
	void *function;
	void *original;

	unsigned long address;
	struct ftrace_ops ops;
};

/*
 * x86_64 kernels have a special naming convention for syscall entry points in newer kernels.
 * That's what you end up with if an architecture has 3 (three) ABIs for system calls.
 */
#ifdef PTREGS_SYSCALL_STUBS
#define SYSCALL_NAME(name) ("__x64_" name)
#else
#define SYSCALL_NAME(name) (name)
#endif

#define HOOK(_name, _function, _original)	\
	{					\
		.name = SYSCALL_NAME(_name),	\
		.function = (_function),	\
		.original = (_original),	\
	}


int fh_install_hook(struct ftrace_hook *hook);
void fh_remove_hook(struct ftrace_hook *hook);
int fh_install_hooks(struct ftrace_hook *hooks, int num);
void fh_remove_hooks(struct ftrace_hook *hooks, int num);
#endif