From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: Re: [PATCH v3] crypto: algapi - make crypto_xor() and crypto_inc() alignment agnostic Date: Sat, 11 Feb 2017 18:55:10 +0800 Message-ID: <20170211105510.GH855@gondor.apana.org.au> References: <1486289172-18604-1-git-send-email-ard.biesheuvel@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-crypto@vger.kernel.org, ebiggers3@gmail.com, Jason@zx2c4.com To: Ard Biesheuvel Return-path: Received: from helcar.hengli.com.au ([209.40.204.226]:36097 "EHLO helcar.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751577AbdBKS7m (ORCPT ); Sat, 11 Feb 2017 13:59:42 -0500 Content-Disposition: inline In-Reply-To: <1486289172-18604-1-git-send-email-ard.biesheuvel@linaro.org> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Sun, Feb 05, 2017 at 10:06:12AM +0000, Ard Biesheuvel wrote: > Instead of unconditionally forcing 4 byte alignment for all generic > chaining modes that rely on crypto_xor() or crypto_inc() (which may > result in unnecessary copying of data when the underlying hardware > can perform unaligned accesses efficiently), make those functions > deal with unaligned input explicitly, but only if the Kconfig symbol > HAVE_EFFICIENT_UNALIGNED_ACCESS is set. This will allow us to drop > the alignmasks from the CBC, CMAC, CTR, CTS, PCBC and SEQIV drivers. > > For crypto_inc(), this simply involves making the 4-byte stride > conditional on HAVE_EFFICIENT_UNALIGNED_ACCESS being set, given that > it typically operates on 16 byte buffers. > > For crypto_xor(), an algorithm is implemented that simply runs through > the input using the largest strides possible if unaligned accesses are > allowed. If they are not, an optimal sequence of memory accesses is > emitted that takes the relative alignment of the input buffers into > account, e.g., if the relative misalignment of dst and src is 4 bytes, > the entire xor operation will be completed using 4 byte loads and stores > (modulo unaligned bits at the start and end). Note that all expressions > involving misalign are simply eliminated by the compiler when > HAVE_EFFICIENT_UNALIGNED_ACCESS is defined. > > Signed-off-by: Ard Biesheuvel Patch applied. Thanks. -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt