ref: 7611e66c4a272e9e4ada31a6996670298a476dff
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);