extern void validate(void);
extern void protect_control_stack_guard_page(pid_t t_id, int protect_p);
extern void protect_control_stack_return_guard_page(pid_t t_id, int protect_p);
extern void validate(void);
extern void protect_control_stack_guard_page(pid_t t_id, int protect_p);
extern void protect_control_stack_return_guard_page(pid_t t_id, int protect_p);