From: Jan Beulich <jbeulich@suse.com>
Date: Thu, 1 Feb 2018 10:32:45 +0000 (+0100)
Subject: x86/shim: don't use 32-bit compare on boolean variable
X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~651
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=98dc9606868a807206ad0f4c3a45046d4e0e1260;p=xen.git

x86/shim: don't use 32-bit compare on boolean variable

Current upstream gas silently assumes 32-bit operand size for most
operations where the size can't be inferred from an involved register
(my own one doesn't anymore, which is how I've noticed this). It is pure
luck that the 3 bytes following pvh_boot are currently padding ones.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
---

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 3cb66fc06b..63bc1b3621 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -585,7 +585,7 @@ trampoline_setup:
         push    %eax                /* Magic number. */
         call    reloc
 #ifdef CONFIG_PVH_GUEST
-        cmp     $0, sym_fs(pvh_boot)
+        cmpb    $0, sym_fs(pvh_boot)
         je      1f
         mov     %eax, sym_fs(pvh_start_info_pa)
         jmp     2f