From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751712AbdBJNVs (ORCPT ); Fri, 10 Feb 2017 08:21:48 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:55798 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751355AbdBJNVq (ORCPT ); Fri, 10 Feb 2017 08:21:46 -0500 Date: Fri, 10 Feb 2017 14:19:25 +0100 From: Greg Kroah-Hartman To: Ben Hutchings Cc: Vineet Gupta , stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4.4 12/23] ARC: [arcompact] handle unaligned access delay slot corner case Message-ID: <20170210131925.GA6905@kroah.com> References: <20170131053624.926643555@linuxfoundation.org> <20170131053625.463159338@linuxfoundation.org> <1486731108.2900.68.camel@decadent.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1486731108.2900.68.camel@decadent.org.uk> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 10, 2017 at 12:51:48PM +0000, Ben Hutchings wrote: > On Tue, 2017-01-31 at 06:37 +0100, Greg Kroah-Hartman wrote: > > 4.4-stable review patch.  If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Vineet Gupta > > > > commit 9aed02feae57bf7a40cb04ea0e3017cb7a998db4 upstream. > > > > After emulating an unaligned access in delay slot of a branch, we > > pretend as the delay slot never happened - so return back to actual > > branch target (or next PC if branch was not taken). > > > > Curently we did this by handling STATUS32.DE, we also need to clear the > > BTA.T bit, which is disregarded when returning from original misaligned > > exception, but could cause weirdness if it took the interrupt return > > path (in case interrupt was acive too) > > > > One ARC700 customer ran into this when enabling unaligned access fixup > > for kernel mode accesses as well > > > > Signed-off-by: Vineet Gupta > > Signed-off-by: Greg Kroah-Hartman > > > > --- > >  arch/arc/kernel/unaligned.c |    3 ++- > >  1 file changed, 2 insertions(+), 1 deletion(-) > > > > --- a/arch/arc/kernel/unaligned.c > > +++ b/arch/arc/kernel/unaligned.c > > @@ -241,8 +241,9 @@ int misaligned_fixup(unsigned long addre > >   if (state.fault) > >   goto fault; > >   > > + /* clear any remanants of delay slot */ > >   if (delay_mode(regs)) { > > - regs->ret = regs->bta; > > + regs->ret = regs->bta ~1U; > > Unless you're doing something terrible with macros, this is missing an > & operator. I doubt this even compiled (looks like it's only used in > some ARC configurations). Hah, that's funny, it's obvious it isn't part of anyone's build tests, so I guess it must be just fine :) thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:55798 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751355AbdBJNVq (ORCPT ); Fri, 10 Feb 2017 08:21:46 -0500 Date: Fri, 10 Feb 2017 14:19:25 +0100 From: Greg Kroah-Hartman To: Ben Hutchings Cc: Vineet Gupta , stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4.4 12/23] ARC: [arcompact] handle unaligned access delay slot corner case Message-ID: <20170210131925.GA6905@kroah.com> References: <20170131053624.926643555@linuxfoundation.org> <20170131053625.463159338@linuxfoundation.org> <1486731108.2900.68.camel@decadent.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1486731108.2900.68.camel@decadent.org.uk> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Feb 10, 2017 at 12:51:48PM +0000, Ben Hutchings wrote: > On Tue, 2017-01-31 at 06:37 +0100, Greg Kroah-Hartman wrote: > > 4.4-stable review patch.��If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Vineet Gupta > > > > commit 9aed02feae57bf7a40cb04ea0e3017cb7a998db4 upstream. > > > > After emulating an unaligned access in delay slot of a branch, we > > pretend as the delay slot never happened - so return back to actual > > branch target (or next PC if branch was not taken). > > > > Curently we did this by handling STATUS32.DE, we also need to clear the > > BTA.T bit, which is disregarded when returning from original misaligned > > exception, but could cause weirdness if it took the interrupt return > > path (in case interrupt was acive too) > > > > One ARC700 customer ran into this when enabling unaligned access fixup > > for kernel mode accesses as well > > > > Signed-off-by: Vineet Gupta > > Signed-off-by: Greg Kroah-Hartman > > > > --- > > �arch/arc/kernel/unaligned.c |����3 ++- > > �1 file changed, 2 insertions(+), 1 deletion(-) > > > > --- a/arch/arc/kernel/unaligned.c > > +++ b/arch/arc/kernel/unaligned.c > > @@ -241,8 +241,9 @@ int misaligned_fixup(unsigned long addre > > � if (state.fault) > > � goto fault; > > � > > + /* clear any remanants of delay slot */ > > � if (delay_mode(regs)) { > > - regs->ret = regs->bta; > > + regs->ret = regs->bta ~1U; > > Unless you're doing something terrible with macros, this is missing an > & operator. I doubt this even compiled (looks like it's only used in > some ARC configurations). Hah, that's funny, it's obvious it isn't part of anyone's build tests, so I guess it must be just fine :) thanks, greg k-h