ref: b1d89be9c61f4ab4c470dc480077fc90a00c4294
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);