linux-kernel - Re: [PATCH] crypto: twofish-avx

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Message-ID: <20120705234612.GD29301@khazad-dum.debian.net>
Date:	Thu, 5 Jul 2012 20:46:12 -0300
From:	Henrique de Moraes Holschuh <hmh@....eng.br>
To:	Johannes Goetzfried 
	<Johannes.Goetzfried@...ormatik.stud.uni-erlangen.de>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH] crypto: twofish-avx - remove useless instruction

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
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