From: Michael Brown <mcb30@etherboot.org>
Date: Sun, 28 Sep 2008 23:36:11 +0000 (+0100)
Subject: [pcbios] Save/restore %es in INT 15,e820
X-Git-Tag: v0.9.5~9
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=50dc9344b7265915f5b9b1f795d024e775e3ae49;p=thirdparty%2Fipxe.git

[pcbios] Save/restore %es in INT 15,e820

Our INT 15,e820 code was setting %es=%ss (as part of the "look ahead
in the memory map" logic), but failing to restore %es afterwards.
This is a serious bug, but wasn't affecting many platforms because
almost all callers seem to set %es=%ss anyway.
---

diff --git a/src/arch/i386/firmware/pcbios/e820mangler.S b/src/arch/i386/firmware/pcbios/e820mangler.S
index ad773f741..437efa776 100644
--- a/src/arch/i386/firmware/pcbios/e820mangler.S
+++ b/src/arch/i386/firmware/pcbios/e820mangler.S
@@ -436,6 +436,7 @@ get_mangled_e820:
 
 	/* Peek ahead to see if there are any further nonempty regions */
 	pushal
+	pushw	%es
 	subw	$20, %sp
 	movl	$0xe820, %eax
 	movl	$SMAP, %edx
@@ -445,6 +446,7 @@ get_mangled_e820:
 	movw	%sp, %di
 	call	get_nonempty_e820
 	addr32 leal 20(%esp), %esp /* avoid changing flags */
+	popw	%es
 	popal
 	jnc	99f /* There are further nonempty regions */