Re: [PATCH v7 7/9] crypto: x86/polyval: Add PCLMULQDQ accelerated implementation of POLYVAL

From: Eric Biggers <ebiggers@kernel.org>
To: Nathan Huckleberry <nhuck@google.com>
Cc: linux-crypto@vger.kernel.org, linux-fscrypt@vger.kernel.org,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org,
	Paul Crowley <paulcrowley@google.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Ard Biesheuvel <ardb@kernel.org>
Subject: Re: [PATCH v7 7/9] crypto: x86/polyval: Add PCLMULQDQ accelerated implementation of POLYVAL
Date: Mon, 9 May 2022 14:44:12 -0700	[thread overview]
Message-ID: <YnmLLEKTBoYLjiqm@sol.localdomain> (raw)
In-Reply-To: <20220509191107.3556468-8-nhuck@google.com>

On Mon, May 09, 2022 at 07:11:05PM +0000, Nathan Huckleberry wrote:
> diff --git a/arch/x86/crypto/polyval-clmulni_asm.S b/arch/x86/crypto/polyval-clmulni_asm.S
[...]
> +/*
> + * Computes the product of two 128-bit polynomials at the memory locations
> + * specified by (MSG + 16*i) and (KEY_POWERS + 16*i) and XORs the components of
> + * the 256-bit product into LO, MI, HI.
> + *
> + * Given:
> + *   X = [X_1 : X_0]
> + *   Y = [Y_1 : Y_0]
> + *
> + * We compute:
> + *   LO += X_0 * Y_0
> + *   MI += (X_0 + X_1) * (Y_0 + Y_1)
> + *   HI += X_1 * Y_1

The above comment (changed in v7) is describing Karatsuba multiplication, but
the actual code is using schoolbook multiplication.

Otherwise this looks good:

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

- Eric