From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: Re: [PATCH] crypto: x86/aes - Don't use %rbp as temporary register Date: Thu, 18 May 2017 19:50:17 -0700 Message-ID: <20170519025017.GA14204@zzz> References: <20170517040308.406-1-ebiggers3@gmail.com> <20170517204427.lwvzonoa26paoitk@treble> <20170517222141.GA60476@gmail.com> <20170519015632.byuezk5ky22rqnkt@treble> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-crypto@vger.kernel.org, Herbert Xu , "David S . Miller" , x86@kernel.org, linux-kernel@vger.kernel.org, Eric Biggers To: Josh Poimboeuf Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:35534 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756044AbdESCuU (ORCPT ); Thu, 18 May 2017 22:50:20 -0400 Content-Disposition: inline In-Reply-To: <20170519015632.byuezk5ky22rqnkt@treble> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, May 18, 2017 at 08:56:32PM -0500, Josh Poimboeuf wrote: > > > > Hmm, it looks like a number of other algorithms in arch/x86/crypto/ use %rbp (or > > %ebp), e.g. blowfish, camellia, cast5, and aes-i586. Presumably they have the > > same problem. I'm a little confused: do these all need to be fixed, and > > when/why did this start being considered broken? > > This warning was only recently added, with the goal of flushing out > these types of issues with hand-coded asm to make frame pointer based > stack traces more reliable. I can take a look at fixing the rest of > them if you want. > Okay. I'm worried you might run into one that is difficult to fix due to lack of spare registers. But if you're interested in looking into it, please go ahead. Thanks! Eric