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Message-ID: <0f96bc45b0394ffa80ff215f4db8092c577a1d91.camel@strongswan.org>
Subject: Re: [PATCH] crypto: x86/chacha-sse3 - use unaligned loads for state
 array
From:   Martin Willi <martin@strongswan.org>
To:     Ard Biesheuvel <ardb@kernel.org>, linux-crypto@vger.kernel.org
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        Eric Biggers <ebiggers@kernel.org>
Date:   Wed, 08 Jul 2020 13:56:23 +0200
In-Reply-To: <20200708091118.1389-1-ardb@kernel.org>
References: <20200708091118.1389-1-ardb@kernel.org>
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> Due to the fact that the x86 port does not support allocating objects
> on the stack with an alignment that exceeds 8 bytes, we have a rather
> ugly hack in the x86 code for ChaCha to ensure that the state array
> is aligned to 16 bytes, allowing the SSE3 implementation of the
> algorithm to use aligned loads.
> 
> Given that the performance benefit of using of aligned loads appears
> to be limited (~0.25% for 1k blocks using tcrypt on a Corei7-8650U),
> and the fact that this hack has leaked into generic ChaCha code,
> let's just remove it.

Reviewed-by: Martin Willi <martin@strongswan.org>

Thanks,
Martin