Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 21 Oct 2020 21:59:49 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        David Laight <David.Laight@aculab.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/6] crypto: lib/sha256 - Clear W[] in sha256_update()
 instead of sha256_transform()
Message-ID: <20201022045949.GF857@sol.localdomain>
References: <20201020203957.3512851-1-nivedita@alum.mit.edu>
 <20201020203957.3512851-4-nivedita@alum.mit.edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20201020203957.3512851-4-nivedita@alum.mit.edu>
Precedence: bulk

On Tue, Oct 20, 2020 at 04:39:54PM -0400, Arvind Sankar wrote:
> The temporary W[] array is currently zeroed out once every call to
> sha256_transform(), i.e. once every 64 bytes of input data. Moving it to
> sha256_update() instead so that it is cleared only once per update can
> save about 2-3% of the total time taken to compute the digest, with a
> reasonable memset() implementation, and considerably more (~20%) with a
> bad one (eg the x86 purgatory currently uses a memset() coded in C).
> 
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>

Looks good,

Reviewed-by: Eric Biggers <ebiggers@google.com>