ref: 44f728861fa35ba070e36bb60c2694e7e979a37f
dir: /include/bits/linux/amd64/arch/sigaction.h/
#define SA_RESTORER 0x04000000
struct sigaction {
void (*sa_handler)(int);
unsigned long sa_flags;
void (*sa_restorer)(void);
unsigned sa_mask[2];
};
extern int __sigaction(int, struct sigaction *, struct sigaction *, size_t);