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]

Message-ID: <4B7D8FA5.40901@zytor.com>
Date:	Thu, 18 Feb 2010 11:06:13 -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 10:49 AM, Luca Barbieri wrote:
>> This really sounds like the wrong optimization.  These functions aren't
>> exactly all that complex in assembly (which would also allow them to be
>> simple cli/do stuff/sti), and instead relying on gcc features which may
>> or may not be well supported on x86 is inviting breakage down the line.
>>
>> That is particularly damaging, since the remaining 486-class users tend
>> to be deeply embedded and thus we only find problems later.
> 
> There is the downside of adding a whole 386/486-specific implementation.
> 
> It's not too hard though, and if we don't care about 486 SMP, it may
> be a better option.

We don't care about 486 SMP.  And yes, I think it is a better option.
At least an assembly option, once implemented, will *stay* implemented
and won't break due to some obscure gcc change.

	-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/