// The TOD clock on s390 counts from the year 1900 in ~250ps intervals.
	// This means that since about 1972 the msb has been set, making the
	// result of a call to STORE CLOCK (stck) a negative number.
	// We clear the msb to make it positive.
	STCK	ret+0(FP)      // serialises before and after call
	MOVD	ret+0(FP), R3  // R3 will wrap to 0 in the year 2043
	SLD	$1, R3
	SRD	$1, R3
	MOVD	R3, ret+0(FP)
	RET