From 7e14bd81f42ddab2dda331a3395ec36b3a299837 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Tue, 7 Dec 2010 17:19:36 -0500
Subject: [PATCH] runtime: debugging help on 386

R=r
CC=golang-dev
https://golang.org/cl/3502041
---
 src/pkg/runtime/386/asm.s | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/pkg/runtime/386/asm.s b/src/pkg/runtime/386/asm.s
index deb7b12f92..84f5367e51 100644
--- a/src/pkg/runtime/386/asm.s
+++ b/src/pkg/runtime/386/asm.s
@@ -177,7 +177,9 @@ TEXT runtime·morestack(SB),7,$0
 	// Call newstack on m's scheduling stack.
 	MOVL	m_g0(BX), BP
 	MOVL	BP, g(CX)
-	MOVL	(m_sched+gobuf_sp)(BX), SP
+	MOVL	(m_sched+gobuf_sp)(BX), AX
+	MOVL	-4(AX), BX	// fault if CALL would, before smashing SP
+	MOVL	AX, SP
 	CALL	runtime·newstack(SB)
 	MOVL	$0, 0x1003	// crash if newstack returns
 	RET
-- 
2.48.1