--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libgo/misc/cgo/test/issue9400/asm_amd64x.s	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,27 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64 amd64p32
+// +build !gccgo
+
+#include "textflag.h"
+
+TEXT ·RewindAndSetgid(SB),NOSPLIT,$0-0
+	// Rewind stack pointer so anything that happens on the stack
+	// will clobber the test pattern created by the caller
+	ADDQ	$(1024 * 8), SP
+
+	// Ask signaller to setgid
+	MOVL	$1, ·Baton(SB)
+
+	// Wait for setgid completion
+loop:
+	PAUSE
+	MOVL	·Baton(SB), AX
+	CMPL	AX, $0
+	JNE	loop
+
+	// Restore stack
+	SUBQ	$(1024 * 8), SP
+	RET