linux-kernel - Re: [PATCH v4 07/14] clocksource: mips-gic-timer: Always use cluster 0 counter as clocksource

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: <Zo1Psqq9VUvW3D96@alpha.franken.de>
Date: Tue, 9 Jul 2024 16:56:50 +0200
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>,
	Aleksandar Rikalo <aleksandar.rikalo@...mia.com>,
	Aleksandar Rikalo <arikalo@...il.com>,
	Chao-ying Fu <cfu@...ecomp.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Greg Ungerer <gerg@...nel.org>, Hauke Mehrtens <hauke@...ke-m.de>,
	Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
	linux-kernel@...r.kernel.org,
	"linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
	Marc Zyngier <maz@...nel.org>,
	"paulburton@...nel.org" <paulburton@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Serge Semin <fancer.lancer@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>
Subject: Re: [PATCH v4 07/14] clocksource: mips-gic-timer: Always use cluster
 0 counter as clocksource

On Tue, Jul 09, 2024 at 04:44:30PM +0200, Daniel Lezcano wrote:
> On 09/07/2024 10:53, Thomas Bogendoerfer wrote:
> > On Tue, Jul 09, 2024 at 09:47:52AM +0800, Jiaxun Yang wrote:
> > > 
> > > 
> > > 在2024年7月9日七月 上午12:36，Daniel Lezcano写道：
> > > > On 11/05/2024 12:43, Aleksandar Rikalo wrote:
> > > > > From: Paul Burton <paulburton@...nel.org>
> > > > > 
> > > > > In a multi-cluster MIPS system we have multiple GICs - one in each
> > > > > cluster - each of which has its own independent counter. The counters in
> > > > > each GIC are not synchronised in any way, so they can drift relative to
> > > > > one another through the lifetime of the system. This is problematic for
> > > > > a clocksource which ought to be global.
> > > > > 
> > > > > Avoid problems by always accessing cluster 0's counter, using
> > > > > cross-cluster register access. This adds overhead so we only do so on
> > > > > systems where we actually have CPUs present in multiple clusters.
> > > > > For now, be extra conservative and don't use gic counter for vdso or
> > > > > sched_clock in this case.
> > > > > 
> > > > > Signed-off-by: Paul Burton <paulburton@...nel.org>
> > > > > Signed-off-by: Chao-ying Fu <cfu@...ecomp.com>
> > > > > Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@...mia.com>
> > > > > Signed-off-by: Aleksandar Rikalo <aleksandar.rikalo@...mia.com>
> > > > > ---
> > > > 
> > > > Applied patch 7 and 8
> > > 
> > > I think it won't compile without patch 1 being applid.
> > > 
> > > Thomas, do you mind to apply patch 1 for now? Given that it's just some extra
> > > function definitions.
> > 
> > no problem, I've applied patch 1 und 2 to mips-next.
> 
> Usually we create a shared immutable branch, but as we are close to the PR,
> I propose I ack these two patches and let them go through the mips tree this
> time

works for me, as well.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]