From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753728AbbEHNm5 (ORCPT ); Fri, 8 May 2015 09:42:57 -0400 Received: from mail-la0-f48.google.com ([209.85.215.48]:36431 "EHLO mail-la0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751030AbbEHNm4 (ORCPT ); Fri, 8 May 2015 09:42:56 -0400 From: Rasmus Villemoes To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Cc: Rasmus Villemoes , linux-kernel@vger.kernel.org Subject: [PATCH] x86: tell the world boot_params is 16-byte aligned Date: Fri, 8 May 2015 15:42:33 +0200 Message-Id: <1431092553-12914-1-git-send-email-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.1.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It doesn't matter much, but this disassembly makes me cry a little bit: ffffffff81f21223 : ffffffff81f21223: 55 push %rbp ffffffff81f21224: 48 c7 c0 40 c2 02 82 mov $0xffffffff8202c240,%rax ffffffff81f2122b: 48 89 fe mov %rdi,%rsi ffffffff81f2122e: a8 01 test $0x1,%al The reason is that boot_params is defined with __attribute__((aligned(16))) in boot/main.c, but other translation units only see the packed attribute on the definition of struct boot_params, so assume the worst. Making the de facto alignment public has this effect: $ scripts/bloat-o-meter /tmp/vmlinux.{defconfig,align} add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-230 (-230) function old new delta copy_bootdata 444 214 -230 Signed-off-by: Rasmus Villemoes --- arch/x86/include/asm/setup.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h index f69e06b283fb..dcd6d5fc2f12 100644 --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -64,7 +64,7 @@ static inline void x86_ce4100_early_setup(void) { } /* * This is set up by the setup-routine at boot-time */ -extern struct boot_params boot_params; +extern struct boot_params boot_params __attribute__((aligned(16))); static inline bool kaslr_enabled(void) { -- 2.1.3