linux-kernel - Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running perfctrs

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: <1282896681.1975.1760.camel@laptop>
Date:	Fri, 27 Aug 2010 10:11:21 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Robert Richter <robert.richter@....com>
Cc:	Cyrill Gorcunov <gorcunov@...il.com>,
	Don Zickus <dzickus@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Lin Ming <ming.m.lin@...el.com>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running
 perfctrs

On Fri, 2010-08-27 at 09:57 +0200, Robert Richter wrote:
> On 26.08.10 14:02:50, Cyrill Gorcunov wrote:
> > > diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
> > > index 4539b4b..9e65a7b 100644
> > > --- a/arch/x86/kernel/cpu/perf_event_intel.c
> > > +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> > > @@ -777,7 +777,9 @@ again:
> > >  
> > >  done:
> > >  	intel_pmu_enable_all(0);
> > > -	return handled;
> > > +	if (!handled)
> > > +		return handled;
> > > +	return ++handled;
> > >  }
> > >  
> > >  static struct event_constraint *
> > > 
> > 
> > ok, it seems it just treat any unknown nmi as being came from PMU, no?
> 
> Yes, this just throws away all unknown nmis after a perf nmi. It
> disables unknown nmi detection on this cpu type.

Wouldn't returning 2 be more sensible, then it would only eat a few
unknowns after each pmi? (Still assuming you return 0 when there really
was nothing to do)
--
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/