Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753767AbcLND1R (ORCPT ); Tue, 13 Dec 2016 22:27:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60600 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751256AbcLND1P (ORCPT ); Tue, 13 Dec 2016 22:27:15 -0500 From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Borislav Petkov , Andy Lutomirski Subject: [PATCH 1/2] x86/boot/64: use 'push' instead of 'call' in start_cpu() Date: Tue, 13 Dec 2016 21:25:35 -0600 Message-Id: <4d8a1952759721d42d1e62ba9e4a7e3ac5df8574.1481685203.git.jpoimboe@redhat.com> In-Reply-To: References: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 14 Dec 2016 03:25:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 933 Lines: 26 start_cpu() pushes a text address on the stack so that stack traces from idle tasks will show start_cpu() at the end. But it uses a call instruction to do that, which is rather obtuse. Use a straightforward push instead. Suggested-by: Borislav Petkov Signed-off-by: Josh Poimboeuf --- arch/x86/kernel/head_64.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 90de288..1facaf4 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -298,7 +298,7 @@ ENTRY(start_cpu) * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect, * address given in m16:64. */ - call 1f # put return address on stack for unwinder + pushq $1f # put return address on stack for unwinder 1: xorq %rbp, %rbp # clear frame pointer movq initial_code(%rip), %rax pushq $__KERNEL_CS # set correct cs -- 2.7.4