runtime: correct assembly for openbsd/arm64

Correct the pipe and pipe2 implementations by using the correct RSP offsets,
used to store and return the file descriptor array.

Fix setNonblock by using the correct immediate value for O_NONBLOCK and
replace EOR (exclusive OR) with ORR.

Also correct the write1 implementation, which has a uintptr value for the fd
argument.

Change-Id: Ibca77af44b649e8bb330ca54f9c36a7a8b0f9cea
Reviewed-on: https://go-review.googlesource.com/c/go/+/212765
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/runtime/sys_openbsd_arm64.s

@@ -65,7 +65,7 @@ TEXT runtime·read(SB),NOSPLIT|NOFRAME,$0
 
 // func pipe() (r, w int32, errno int32)
 TEXT runtime·pipe(SB),NOSPLIT|NOFRAME,$0-12
-	MOVD	RSP, R0
+	MOVD	$r+0(FP), R0
 	MOVW	$0, R1
 	MOVD	$101, R8		// sys_pipe2
 	SVC
@@ -76,7 +76,7 @@ TEXT runtime·pipe(SB),NOSPLIT|NOFRAME,$0-12
 
 // func pipe2(flags int32) (r, w int32, errno int32)
 TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20
-	ADD	$8, RSP, R0
+	MOVD	$r+8(FP), R0
 	MOVW	flags+0(FP), R1
 	MOVD	$101, R8		// sys_pipe2
 	SVC
@@ -86,7 +86,7 @@ TEXT runtime·pipe2(SB),NOSPLIT|NOFRAME,$0-20
 	RET
 
 TEXT runtime·write1(SB),NOSPLIT|NOFRAME,$0
-	MOVW	fd+0(FP), R0		// arg 1 - fd
+	MOVD	fd+0(FP), R0		// arg 1 - fd
 	MOVD	p+8(FP), R1		// arg 2 - buf
 	MOVW	n+16(FP), R2		// arg 3 - nbyte
 	MOVD	$4, R8			// sys_write
@@ -428,8 +428,8 @@ TEXT runtime·setNonblock(SB),NOSPLIT|NOFRAME,$0-4
 	MOVD	$0, R2			// arg 3
 	MOVD	$92, R8			// sys_fcntl
 	SVC
-	MOVD	$0x800, R2		// O_NONBLOCK
-	EOR	R0, R2			// arg 3 - flags
+	MOVD	$4, R2			// O_NONBLOCK
+	ORR	R0, R2			// arg 3 - flags
 	MOVW	fd+0(FP), R0		// arg 1 - fd
 	MOVD	$4, R1			// arg 2 - cmd (F_SETFL)
 	MOVD	$92, R8			// sys_fcntl