From: Herbert Xu Subject: Re: x86-64: Maintain 16-byte stack alignment Date: Wed, 11 Jan 2017 11:11:24 +0800 Message-ID: <20170111031124.GA4515@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 Cc: Linux Kernel Mailing List , Linux Crypto Mailing List , Ingo Molnar , Thomas Gleixner , Andy Lutomirski , Ard Biesheuvel To: Linus Torvalds Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Tue, Jan 10, 2017 at 09:05:28AM -0800, Linus Torvalds wrote: > On Tue, Jan 10, 2017 at 6:39 AM, Herbert Xu wrote: > > > > BTW this is with Debian gcc 4.7.2 which does not allow an 8-byte > > stack alignment as attempted by the Makefile: > > 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. Well the only other alternative I see is to ban compilers which enforce 16-byte stack alignment, such as gcc 4.7.2. Or is there another way? Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt