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]
Date:	Tue, 1 Jul 2014 10:14:13 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	"HATAYAMA, Daisuke" <d.hatayama@...fujitsu.com>, hpa@...or.com,
	Don Zickus <dzickus@...hat.com>, matt@...sole-pimps.org,
	acme@...nel.org, mingo@...hat.com, paulus@...ba.org,
	tglx@...utronix.de, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] perf/x86/intel: ignore CondChgd bit to avoid false
 NMI handling

On Mon, Jun 30, 2014 at 03:22:24PM -0700, Andi Kleen wrote:
> > 
> > I'm also interested in the behaviour of CondChgd bit on Ivy Bridge processors.
> 
> The intended meaning of CondChgd is that a hardware debugger has taken over the
> PMU. It shouldn't really be set in other circumstances.

The SDM utterly and totally fails to mention this, please fix that.

> I think right now for perf it would be best to just ignore it.
> 
> In theory could stop using the PMU, but if some BIOS set it it would
> completely disable perf there. So better to just ignore it.

The even better option would be to kill off SMM mode, all that ever does
is create problems.
--
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/

Powered by blists - more mailing lists