Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Milian Wolff <milian.wolff@kdab.com>
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     Andi Kleen <ak@linux.intel.com>, linux-kernel@vger.kernel.org,
        Jiri Olsa <jolsa@kernel.org>, namhyung@kernel.org,
        linux-perf-users@vger.kernel.org,
        Arnaldo Carvalho <acme@kernel.org>
Subject: Re: PEBS level 2/3 breaks dwarf unwinding! [WAS: Re: Broken dwarf
 unwinding - wrong stack pointer register value?]
Date:   Tue, 06 Nov 2018 21:04:08 +0100
Message-ID: <2102566.fCj8pZGm78@agathebauer>
Organization: KDAB
In-Reply-To: <20181106083957.GB8081@krava>
References: <2335309.gnWok9HYb4@agathebauer>
 <20181106001037.GQ6218@tassilo.jf.intel.com> <20181106083957.GB8081@krava>
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="nextPart1644059.f7Ub7bqP93";
 micalg="sha256"; protocol="application/pkcs7-signature"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

--nextPart1644059.f7Ub7bqP93
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"

On Dienstag, 6. November 2018 09:39:57 CET Jiri Olsa wrote:
> On Mon, Nov 05, 2018 at 04:10:37PM -0800, Andi Kleen wrote:
> > > > > - PMU triggers interrupt and PEBS stores RIP etc.
> > > > > - code continous to execute, possibly changing the stack
> > > > 
> > > > I dont think the code continues to execute.. the stack is ok
> > > 
> > > Are you sure about this? I mean, isn't that the whole reason why we need
> > > PEBS? Generally, if you are sure about this, can you point me to some
> > > documentation on this to allow me to understand it better?
> > 
> > Milian is right.
> > 
> > There is a execution window from PEBS capturing registers to actually
> > triggering the PMU, and if there is stack manipulation in that window
> > the PEBS state might be out of sync with the real stack.
> 
> hum, is this about having 'large pebs' or there's this window
> if there's also only single pebs record allowed? which should
> be case for dwarf unwind
> 
> > The right RIP/RSP to use for the stack unwinding is always the data
> > in the PMI's exception frame on the stack.
> > 
> > Probably would need to modify perf to report those too in addition
> > to the PEBS registers.
> 
> ok, should not be that hard

Where would I look for the source to change here? So far, I only concentrated 
on the userspace side of perf in tools/perf.

Thanks

-- 
Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer
KDAB (Deutschland) GmbH, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt, C++ and OpenGL Experts
--nextPart1644059.f7Ub7bqP93
Content-Type: application/pkcs7-signature; name="smime.p7s"
Content-Disposition: attachment; filename="smime.p7s"
Content-Transfer-Encoding: base64
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--nextPart1644059.f7Ub7bqP93--