From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:44940 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726124AbgIBTDS (ORCPT ); Wed, 2 Sep 2020 15:03:18 -0400 Date: Wed, 2 Sep 2020 20:03:06 +0100 From: Mark Rutland Subject: Re: [PATCH v2 0/3] arm64: Convert to ARCH_STACKWALK Message-ID: <20200902190306.GB5875@C02TD0UTHF1T.local> References: <20200819124913.37261-1-broonie@kernel.org> <20200901160626.GE95447@C02TD0UTHF1T.local> <20200902173803.GE6162@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200902173803.GE6162@sirena.org.uk> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Mark Brown Cc: Catalin Marinas , Will Deacon , Vasily Gorbik , Heiko Carstens , Borislav Petkov , Thomas Gleixner , "H. Peter Anvin" , Christian Borntraeger , Ingo Molnar , Jiri Slaby , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Miroslav Benes On Wed, Sep 02, 2020 at 06:38:03PM +0100, Mark Brown wrote: > On Tue, Sep 01, 2020 at 05:06:26PM +0100, Mark Rutland wrote: > > > Just to check, has the skipping logic been tested to work equivalently > > to what we had before? By inspection I think it should, but since it > > relies on function call boundaries it always strikes me as fragile. > > > If you could confirm that (e.g. with LKDTM perhaps?) that'd be great. > > Assuming that looks right, for the series: > > I've tested this with LKDTM and otherwise and didn't spot any issues > (and just did a bit of retesting) but it is a pretty manual process so > it's possible I missed something. It looks like the case Mirolav pointed out (self-bactrace with NULL regs) isn't triggered by LKDTM (since it always causes a backtrace from an exception with non-NULL regs), but we do rely on that elsewhere in the kernel. It might be worth adding an LKDTM test to trigger that. I'll wait for a respin that handles that -- please drop the ack for now. Thanks, Mark.