From: Henrique de Moraes Holschuh Subject: Re: [PATCH] crypto: twofish-avx - remove useless instruction Date: Thu, 5 Jul 2012 20:46:12 -0300 Message-ID: <20120705234612.GD29301@khazad-dum.debian.net> References: <20120705184358.GE2091@kronos.redsun> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Herbert Xu , linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org To: Johannes Goetzfried Return-path: Received: from out1-smtp.messagingengine.com ([66.111.4.25]:41386 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753476Ab2GEXqR (ORCPT ); Thu, 5 Jul 2012 19:46:17 -0400 Content-Disposition: inline In-Reply-To: <20120705184358.GE2091@kronos.redsun> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, 05 Jul 2012, Johannes Goetzfried wrote: > The register %rdx is written, but never read till the end of the encryption > routine. Therefore let's delete the useless instruction. Is it useless, or is it there to harden against some side-channel attack? -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh