linux-kernel - Re: [PATCH] Convert powerpc simple spinlocks into ticket locks

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] [day] [month] [year] [list]

Message-ID: <1392001526.3996.17.camel@pasglop>
Date:	Mon, 10 Feb 2014 14:05:26 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Kumar Gala <galak@...nel.crashing.org>
Cc:	Torsten Duwe <duwe@....de>, Scott Wood <scottwood@...escale.com>,
	Tom Musta <tommusta@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, Paul Mackerras <paulus@...ba.org>,
	Anton Blanchard <anton@...ba.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linuxppc-dev@...ts.ozlabs.org, Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] Convert powerpc simple spinlocks into ticket locks

On Fri, 2014-02-07 at 09:51 -0600, Kumar Gala wrote:
> On Feb 7, 2014, at 3:02 AM, Torsten Duwe <duwe@....de> wrote:
> 
> > On Thu, Feb 06, 2014 at 02:19:52PM -0600, Scott Wood wrote:
> >> On Thu, 2014-02-06 at 18:37 +0100, Torsten Duwe wrote:
> >>> On Thu, Feb 06, 2014 at 05:38:37PM +0100, Peter Zijlstra wrote:
> >> 
> >>>> Can you pair lwarx with sthcx ? I couldn't immediately find the answer
> >>>> in the PowerISA doc. If so I think you can do better by being able to
> >>>> atomically load both tickets but only storing the head without affecting
> >>>> the tail.
> > 
> > Can I simply write the half word, without a reservation, or will the HW caches
> > mess up the other half? Will it ruin the cache coherency on some (sub)architectures?
> 
> The coherency should be fine, I just can’t remember if you’ll lose the reservation by doing this.

Yes you do.

> >> Plus, sthcx doesn't exist on all PPC chips.
> > 
> > Which ones are lacking it? Do all have at least a simple 16-bit store?
> 
> Everything implements a simple 16-bit store, just not everything implements the store conditional of 16-bit data.

Ben.

> - k--
> 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/


--
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/