linux-kernel - Re: bit fields && data tearing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 08 Sep 2014 19:27:14 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	James Bottomley <James.Bottomley@...senPartnership.com>,
	Chris Metcalf <cmetcalf@...era.com>
CC:	Peter Hurley <peter@...leysoftware.com>,
	paulmck@...ux.vnet.ibm.com,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Jakub Jelinek <jakub@...hat.com>,
	Mikael Pettersson <mikpelinux@...il.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Richard Henderson <rth@...ddle.net>,
	Oleg Nesterov <oleg@...hat.com>,
	Miroslav Franc <mfranc@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
	linux-ia64@...r.kernel.org
Subject: Re: bit fields && data tearing

On 09/08/2014 03:43 PM, James Bottomley wrote:
> 
> This was years ago (possibly decades).  We had to implement in-kernel
> unaligned traps for the networking layer because it could access short
> and int fields that weren't of the correct alignment when processing
> packets.  It that's all corrected now, we wouldn't really notice (except
> a bit of a speed up since an unaligned trap effectively places the
> broken out instructions into the bit stream).
> 
> James
> 

Well, ARM doesn't trap, it just silently gives garbage on unaligned
memory references.

	-hpa


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/