From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out1-smtp.messagingengine.com ([66.111.4.25]:56549 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964896AbeE3Ie6 (ORCPT ); Wed, 30 May 2018 04:34:58 -0400 Date: Wed, 30 May 2018 10:34:36 +0200 From: Greg KH To: Michael Neuling Cc: stable@vger.kernel.org, mpe@ellerman.id.au Subject: Re: [PATCH 4.9] powerpc/64s: Clear PCR on boot Message-ID: <20180530083436.GD9685@kroah.com> References: <20180529035629.22343-1-mikey@neuling.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180529035629.22343-1-mikey@neuling.org> Sender: stable-owner@vger.kernel.org List-ID: On Tue, May 29, 2018 at 01:56:29PM +1000, Michael Neuling wrote: > Clear the PCR (Processor Compatibility Register) on boot to ensure we > are not running in a compatibility mode. > > We've seen this cause problems when a crash (and kdump) occurs while > running compat mode guests. The kdump kernel then runs with the PCR > set and causes problems. The symptom in the kdump kernel (also seen in > petitboot after fast-reboot) is early userspace programs taking > sigills on newer instructions (seen in libc). > > Signed-off-by: Michael Neuling > Cc: stable@vger.kernel.org # v4.9 > Signed-off-by: Michael Ellerman > -- > > Greg, This is a backport for v4.9 only since the original patch didn't > apply. > > Commit faf37c44a105f3608115785f17cbbf3500f8bc71 upstream. Thanks for this, and the 4.4 backport, both now queued up. greg k-h