From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751676AbcAWGyT (ORCPT ); Sat, 23 Jan 2016 01:54:19 -0500 Received: from mail-lf0-f68.google.com ([209.85.215.68]:36650 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751374AbcAWGyQ (ORCPT ); Sat, 23 Jan 2016 01:54:16 -0500 From: Alexander Kuleshov To: Thomas Gleixner Cc: Ingo Molnar , "H . Peter Anvin" , Andy Lutomirski , Borislav Petkov , Denys Vlasenko , Andrey Ryabinin , x86@kernel.org, linux-kernel@vger.kernel.org, Alexander Kuleshov Subject: [PATCH] x86/head_64.S: do not use temporary register to check alignment Date: Sat, 23 Jan 2016 12:50:28 +0600 Message-Id: <1453531828-19291-1-git-send-email-kuleshovmail@gmail.com> X-Mailer: git-send-email 2.7.0.25.gfc10eb5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We are using temporary %rax register during checking of kernel address alignment. We can ged rid of it since testl instruction is safe and does not change value of the rbp register. Signed-off-by: Alexander Kuleshov Suggested-by: Brian Gerst --- arch/x86/kernel/head_64.S | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index ffdc0e8..7c21029 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -76,9 +76,7 @@ startup_64: subq $_text - __START_KERNEL_map, %rbp /* Is the address not 2M aligned? */ - movq %rbp, %rax - andl $~PMD_PAGE_MASK, %eax - testl %eax, %eax + testl $~PMD_PAGE_MASK, %ebp jnz bad_address /* -- 2.7.0.25.gfc10eb5