From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable
 function
Date: Thu, 15 Dec 2016 22:09:33 +0100
Message-ID: <20161215210933.GY3207@twins.programming.kicks-ass.net>
References: <8ea3fdff-23c4-b81d-2588-44549bd2d8c1@stressinduktion.org>
 <063D6719AE5E284EB5DD2968C1650D6DB02401ED@AcuExch.aculab.com>
 <707472e1-b385-836d-c4c6-791c1dcc0776@stressinduktion.org>
 <063D6719AE5E284EB5DD2968C1650D6DB02402C0@AcuExch.aculab.com>
 <0f3c3694-c00b-aae2-5b08-25bc64bf6372@stressinduktion.org>
 <063D6719AE5E284EB5DD2968C1650D6DB0240437@AcuExch.aculab.com>
 <f6813084-6f46-0b22-e9c3-97b2e266f8f6@stressinduktion.org>
 <063D6719AE5E284EB5DD2968C1650D6DB0240529@AcuExch.aculab.com>
 <924ef794-eae0-2a6b-508b-069718339edc@stressinduktion.org>
 <CAHmME9pTLFu3-4n6m_OMj5jVWGE-+yC-4CnkynD--H4Nt8_cpA@mail.gmail.com>
Reply-To: kernel-hardening@lists.openwall.com
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>,
	David Laight <David.Laight@aculab.com>,
	Netdev <netdev@vger.kernel.org>,
	"kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>,
	Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	"Daniel J . Bernstein" <djb@cr.yp.to>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Eric Biggers <ebiggers3@gmail.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Return-path: <kernel-hardening-return-5601-glkh-kernel-hardening=m.gmane.org@lists.openwall.com>
List-Post: <mailto:kernel-hardening@lists.openwall.com>
List-Help: <mailto:kernel-hardening-help@lists.openwall.com>
List-Unsubscribe: <mailto:kernel-hardening-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:kernel-hardening-subscribe@lists.openwall.com>
Content-Disposition: inline
In-Reply-To: <CAHmME9pTLFu3-4n6m_OMj5jVWGE-+yC-4CnkynD--H4Nt8_cpA@mail.gmail.com>
List-Id: linux-crypto.vger.kernel.org

On Thu, Dec 15, 2016 at 07:50:36PM +0100, Jason A. Donenfeld wrote:
> There's no 32-bit platform
> that will trap on a 64-bit unaligned access because there's no such
> thing as a 64-bit access there. In short, we're fine.

ARMv7 LPAE is a 32bit architecture that has 64bit load/stores IIRC.

x86 has cmpxchg8b that can do 64bit things and very much wants the u64
aligned.

Also, IIRC we have a few platforms where u64 doesn't carry 8 byte
alignment, m68k or something like that, but yes, you likely don't care.

Just to make life interesting...