linux-kernel - Re: [PATCH 03/20] x86, mce: Add persistent MCE event

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20101111061725.GA19321@aftab>
Date:	Thu, 11 Nov 2010 07:17:25 +0100
From:	Borislav Petkov <bp@...64.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Ben Gamari <bgamari@...il.com>,
	"acme@...radead.org" <acme@...radead.org>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/20] x86, mce: Add persistent MCE event

On Wed, Nov 10, 2010 at 05:21:57PM -0500, Ingo Molnar wrote:
> 
> * Ben Gamari <bgamari@...il.com> wrote:
> 
> > On Thu,  4 Nov 2010 16:36:39 +0100, Borislav Petkov <bp@...64.org> wrote:
> > > From: Borislav Petkov <borislav.petkov@....com>
> > > 
> > > Add the necessary glue to enable the mce_record tracepoint on boot
> > > turning it into a persistent event. This exports the MCE buffer
> > > read-only to a userspace daemon which will hook into it through debugfs
> > > when booting is finished.
> > 
> > While MCE technically is a diagnostics service, do we want to start adding 
> > dependencies on debugfs in long-running, common-place daemons? I was under the 
> > impression we were to avoid using debugfs for anything other than values for 
> > one-off debugging.
> 
> See this current discussion thread on lkml:
> 
>    [RFC][PATCH] perf: sysfs type id
> 
> Events are being added to sysfs as we want to avoid the debugfs dependency.

Yep, event enumeration will land in /sysfs eventually but in this case
debugfs is used to export the buffers with the events recorded so far to
the daemon which mmaps them. And I remember also being mentioned that
debugfs will thus be always compiled in because of that.

In any case, we need some kind of a facility with which to export those
buffers for userspace to mmap. sysfs is clearly not that and debugfs is
what we currently use. I'm open for better suggestions though.

Thanks.

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632
--
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/