From: Andy Lutomirski <luto@kernel.org>
Date: Wed, 15 Jul 2015 17:29:39 +0000 (-0700)
Subject: x86/nmi/64: Minor asm simplification
X-Git-Tag: v4.2-rc3~6^2~4
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=23a781e987f05029c4a99a5c145be3efa6eda9f3;p=karo-tx-linux.git

x86/nmi/64: Minor asm simplification

Replace LEA; MOV with an equivalent SUB.  This saves one
instruction.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index d8ab2b201fa1..0fb52526e452 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1420,8 +1420,7 @@ nested_nmi:
 	 * Modify the "iret" frame to point to repeat_nmi, forcing another
 	 * iteration of NMI handling.
 	 */
-	leaq	-1*8(%rsp), %rdx
-	movq	%rdx, %rsp
+	subq	$8, %rsp
 	leaq	-10*8(%rsp), %rdx
 	pushq	$__KERNEL_DS
 	pushq	%rdx