From: Kees Jongenburger <kees.jongenburger@gmail.com>
Date: Wed, 2 Apr 2014 07:28:38 +0000 (+0200)
Subject: libc:x86 fix for get and setcontext assembly calls.
X-Git-Tag: v3.3.0~374
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/rndc-confgen.html?a=commitdiff_plain;h=8991ca4e5afe07c197e25eefce1284bbe0d51497;p=minix.git

libc:x86 fix for get and setcontext assembly calls.

The get and set context calls where wrongly assuming that the value
of arguments passed on the stack where kept unmodified.

Change-Id: I779b08d7f5a6472c5e9dc351ae44abb2acafb3bd
---

diff --git a/lib/libc/arch/i386/sys-minix/ucontext.S b/lib/libc/arch/i386/sys-minix/ucontext.S
index 92ec539d6..e72331a47 100644
--- a/lib/libc/arch/i386/sys-minix/ucontext.S
+++ b/lib/libc/arch/i386/sys-minix/ucontext.S
@@ -34,9 +34,11 @@ ENTRY(_getcontext)
 	cmp $[_UC_IGNFPU|_UC_IGNSIGM], %eax
 	jz 5f				/* Ignore both, skip getuctx */
 	PIC_PROLOGUE
-	push %edx		 
+	push %edx /* push a copy for us */
+	push %edx /* push a copy as function argument */
 	call PIC_PLT(_C_LABEL(getuctx))	/* getuctx(ucp) */
-	pop %edx			/* clean up stack and restore edx */
+	pop %edx	/* clean up stack */
+	pop %edx	/* clean up stack and  restore edx */
 	PIC_EPILOGUE
 
 5:
@@ -96,9 +98,11 @@ ENTRY(setcontext)
 				 * state and signal mask */
 
 	PIC_PROLOGUE
-	push %edx		 
+	push %edx /* push a copy for us */
+	push %edx /* push a copy as function argument */
 	call PIC_PLT(_C_LABEL(setuctx))	/* setuctx(ucp) */
-	pop %edx			/* Clean up stack and restore edx */
+	pop %edx	/* clean up stack */
+	pop %edx	/* clean up stack and  restore edx */
 	PIC_EPILOGUE
 
 5:	/* Restore the registers (except EAX and EDX) */