linux-kernel - Re: [RFC][PATCH 5/5] perfcounter: Add support for kernel hardware breakpoints

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: <1248766000.6987.2759.camel@twins>
Date:	Tue, 28 Jul 2009 09:26:40 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Anton Blanchard <anton@...ba.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Zhaolei <zhaolei@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	"K . Prasad" <prasad@...ux.vnet.ibm.com>,
	Alan Stern <stern@...land.harvard.edu>
Subject: Re: [RFC][PATCH 5/5] perfcounter: Add support for kernel hardware
 breakpoints

On Tue, 2009-07-28 at 02:18 +0200, Frederic Weisbecker wrote:
> 
> I still don't understand why it is needed to reserve breakpoints for
> a group of monitored tasks. Once they have registered their breakpoints,
> the number of necessary hardware registers for these will be available
> every time the task is scheduled.

Its possible to create >4 breakpoint counters. We time-share them.

The only constraint we have is that those within a group should be on
the 'PMU' at the same time.

If you have no groups, a single available breakpoint slot should suffice
for any configuration (although more is better), but if you get groups
you have to guarantee your created group can run.

--
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/