From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750803AbdALHFp (ORCPT ); Thu, 12 Jan 2017 02:05:45 -0500 Received: from helcar.hengli.com.au ([209.40.204.226]:39365 "EHLO helcar.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750719AbdALHFn (ORCPT ); Thu, 12 Jan 2017 02:05:43 -0500 Date: Thu, 12 Jan 2017 15:05:34 +0800 From: Herbert Xu To: Linus Torvalds Cc: Linux Kernel Mailing List , Linux Crypto Mailing List , Ingo Molnar , Thomas Gleixner , Andy Lutomirski , Ard Biesheuvel Subject: Re: x86-64: Maintain 16-byte stack alignment Message-ID: <20170112070534.GA14016@gondor.apana.org.au> References: <20170110143340.GA3787@gondor.apana.org.au> <20170110143913.GA3822@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 10, 2017 at 09:05:28AM -0800, Linus Torvalds wrote: > > I'm pretty sure we have random asm code that may not maintain a > 16-byte stack alignment when it calls other code (including, in some > cases, calling C code). > > So I'm not at all convinced that this is a good idea. We shouldn't > expect 16-byte alignment to be something trustworthy. So what if we audited all the x86 assembly code to fix this? Would it then be acceptable to do a 16-byte aligned stack? On the face of it it doesn't seem to be a huge amount of code assuming they mostly live under arch/x86. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt