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 [thread overview]
Message-ID: <2102566.fCj8pZGm78@agathebauer> (raw)
In-Reply-To: <20181106083957.GB8081@krava>
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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
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next prev parent reply other threads:[~2018-11-06 20:04 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-20 22:39 Broken dwarf unwinding - wrong stack pointer register value? Milian Wolff
2018-10-21 20:32 ` Milian Wolff
2018-10-22 10:35 ` Milian Wolff
2018-10-22 11:17 ` Milian Wolff
2018-10-22 13:58 ` Andi Kleen
2018-10-22 19:26 ` Milian Wolff
2018-10-23 4:03 ` Andi Kleen
2018-10-23 10:34 ` Milian Wolff
2018-10-24 14:48 ` Andi Kleen
2018-10-30 22:34 ` Milian Wolff
2018-11-01 22:08 ` PEBS level 2/3 breaks dwarf unwinding! [WAS: Re: Broken dwarf unwinding - wrong stack pointer register value?] Milian Wolff
2018-11-02 11:26 ` Jiri Olsa
2018-11-02 17:56 ` Milian Wolff
2018-11-05 20:51 ` Jiri Olsa
2018-11-05 22:54 ` Milian Wolff
2018-11-06 0:10 ` Andi Kleen
2018-11-06 8:39 ` Jiri Olsa
2018-11-06 17:26 ` Andi Kleen
2018-11-06 20:04 ` Milian Wolff [this message]
2018-11-06 20:24 ` Andi Kleen
2018-11-07 22:41 ` Milian Wolff
2018-11-08 12:41 ` Milian Wolff
2018-11-09 0:55 ` Andi Kleen
2018-11-09 0:54 ` Andi Kleen
2018-11-10 21:42 ` Travis Downs
2018-11-11 1:07 ` Andi Kleen
[not found] ` <CAOBGo4zirLiKX8VcROAE=kAD0+qkF0E-cBv9DtBiQr=_obDv5w@mail.gmail.com>
2018-11-11 2:54 ` Travis Downs
2018-11-12 3:26 ` Andi Kleen
2018-11-14 13:20 ` Milian Wolff
2018-11-15 2:05 ` Travis Downs
2018-11-15 9:10 ` Milian Wolff
2018-11-15 19:00 ` Andi Kleen
2018-11-15 2:15 ` Travis Downs
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