linux-kernel - Re: Mixed group of sw/hw counters are not started if sw counter is group leader

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

Message-ID: <20130201101347.GB1078@krava.brq.redhat.com>
Date:	Fri, 1 Feb 2013 11:13:48 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Vince Weaver <vince@...ter.net>
Cc:	Andreas Hollmann <hollmann@...tum.de>,
	linux-perf-users@...r.kernel.org,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Mixed group of sw/hw counters are not started if sw counter is
 group leader

On Tue, Jan 29, 2013 at 11:56:01AM -0500, Vince Weaver wrote:
> On Tue, 29 Jan 2013, Jiri Olsa wrote:
> 
> > ok, there's been perf fixies wrt enable events groups, but they
> > landed in 3.8-rc1.. until that point all the group members are
> > specifically enabled, so that's why your perf is working and
> > mine not..
> > 
> > Anyway, seems like there's bug in kernel code when we have group
> > with sw and hw counters.
> > 
> > Attached path makes your test case working for me. I'll give it some
> > more thoughts & testing and send it out soon. If you like to test,
> > please go ahead.
> 
> I've added a test to my perf_event_test testsuite to look for this bug.
>    http://www.eece.maine.edu/~vweaver/projects/perf_events/validation/
> 
> In my (minimal) testing so far it looks like this bug does exist in 3.2
> but does not in 2.6.35.  Is anyone curious enough to do a bisect to find 
> out when it was introduced?

I found this started at v2.6.37 where following commit that introduced
the group moving was added:

perf: Complete software pmu grouping
commit b04243ef7006cda301819f54ee7ce0a3632489e3
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Date:   Fri Sep 17 11:28:48 2010 +0200

I could not get finer bisection within 2.6.37 because the kernel
deadlocked each time I ran the test.

But it seems this problem is there from the introducing
of the group moving.

CCing more folks and lkml

jirka
--
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/