linux-kernel - Re: [PATCH 09/10] x86-32: use SSE for atomic64

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:	Thu, 18 Feb 2010 11:07:12 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Luca Barbieri <luca@...a-barbieri.com>
CC:	Andi Kleen <andi@...stfloor.org>, mingo@...e.hu,
	a.p.zijlstra@...llo.nl, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/10] x86-32: use SSE for atomic64_read/set if available

On 02/18/2010 10:42 AM, Luca Barbieri wrote:
>> We already do that kind of stuff, using
>> kernel_fpu_begin()..kernel_fpu_end().  We went through some pain a bit
>> ago to clean up "private hacks" that complicated things substantially.
> 
> But that saves the whole FPU state on the first usage, and also
> triggers a fault when userspace attempts to use it again.
> Additionally it does a clts/stts every time which is slow for small
> algorithms (lke the atomic64 routines).
> 
> The first issue can be solved by using SSE and saving only the used
> registers, and the second with lazy TS flag restoring.
> 

Again, I want to see a strong use case before even *considering* making
the rules we already have any more complex.

	-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/