linux-kernel - Re: [PATCH 00/12] x86/crypto: Fix RBP usage in several crypto .S files

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Date:   Wed, 6 Sep 2017 19:15:18 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Eric Biggers <ebiggers3@...il.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Mathias Krause <minipli@...glemail.com>,
        Chandramouli Narayanan <mouli@...ux.intel.com>,
        Jussi Kivilinna <jussi.kivilinna@....fi>,
        Peter Zijlstra <peterz@...radead.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>,
        Andy Lutomirski <luto@...nel.org>, Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH 00/12] x86/crypto: Fix RBP usage in several crypto .S
 files

On Fri, Sep 01, 2017 at 05:09:19PM -0700, Eric Biggers wrote:
> Hi Josh,
> 
> On Tue, Aug 29, 2017 at 01:05:33PM -0500, Josh Poimboeuf wrote:
> > Many of the x86 crypto functions use RBP as a temporary register.  This
> > breaks frame pointer convention, and breaks stack traces when unwinding
> > from an interrupt in the crypto code.
> > 
> > Convert most* of them to leave RBP alone.
> > 
> > These pass the crypto boot tests for me.  Any further testing would be
> > appreciated!
> > 
> > [*] There are still a few crypto files left that need fixing, but the
> >     fixes weren't trivial and nobody reported unwinder warnings about
> >     them yet, so I'm skipping them for now.
> > 
> > Josh Poimboeuf (12):
> >   x86/crypto: Fix RBP usage in blowfish-x86_64-asm_64.S
> >   x86/crypto: Fix RBP usage in camellia-x86_64-asm_64.S
> >   x86/crypto: Fix RBP usage in cast5-avx-x86_64-asm_64.S
> >   x86/crypto: Fix RBP usage in cast6-avx-x86_64-asm_64.S
> >   x86/crypto: Fix RBP usage in des3_ede-asm_64.S
> >   x86/crypto: Fix RBP usage in sha1_avx2_x86_64_asm.S
> >   x86/crypto: Fix RBP usage in sha1_ssse3_asm.S
> >   x86/crypto: Fix RBP usage in sha256-avx-asm.S
> >   x86/crypto: Fix RBP usage in sha256-avx2-asm.S
> >   x86/crypto: Fix RBP usage in sha256-ssse3-asm.S
> >   x86/crypto: Fix RBP usage in sha512-avx2-asm.S
> >   x86/crypto: Fix RBP usage in twofish-avx-x86_64-asm_64.S
> > 
> 
> Thanks for fixing these!  I don't have time to review these in detail, but I ran
> the crypto self-tests on the affected algorithms, and they all pass.  I also
> benchmarked them before and after; the only noticable performance difference was
> that sha256-avx2 and sha512-avx2 became a few percent slower.  I don't suppose
> there is a way around that?  Otherwise it's probably not a big deal.

Thanks for testing.  I might have a way to make sha256-avx2 faster, but
not sha512-avx2.  I'll let you know when I have a patch.

-- 
Josh