root/lib/libthread_xu/arch/x86_64/x86_64/_umtx_sleep_wakeup_err.S
#include <machine/asm.h>
#include <sys/syscall.h>


#define KERNCALL        movq %rcx, %r10; syscall

#define SYSCALL_ERR(x)                                          \
                        ENTRY(__CONCAT(x, _err));               \
                        mov __CONCAT($SYS,x),%rax; KERNCALL; ret; \
                        END(__CONCAT(x, _err))


SYSCALL_ERR(_umtx_sleep)
SYSCALL_ERR(_umtx_wakeup)