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Date: Mon, 10 Oct 2016 16:02:07 +1100
From: Michael Ellerman <mpe@...erman.id.au>
To: Anton Blanchard <anton@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Nicholas Piggin <npiggin@...il.com>,
ravi.bangoria@...ux.vnet.ibm.com, acme@...hat.com,
peterz@...radead.org, mingo@...hat.com,
alexander.shishkin@...ux.intel.com
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: perf TUI fails with "failed to process type: 64"
Anton Blanchard <anton@...ba.org> writes:
> Hi,
>
> Updating to mainline as of last night, I started seeing the following
> error when running the perf report TUI:
>
> 0x46068 [0x8]: failed to process type: 68
>
> This event is just PERF_RECORD_FINISHED_ROUND:
>
> 0x46068 [0x8]: event: 68
> .
> . ... raw event: size 8 bytes
> . 0000: 44 00 00 00 00 00 08 00 D.......
>
> 0x46068 [0x8]: PERF_RECORD_FINISHED_ROUND
>
> Which of course is not our error. It took me a while to find the real
> culprit:
>
> 14c00-14c00 g exc_virt_0x4c00_system_call
^
What's this? The address? If so it's wrong?
> A zero length symbol, which __symbol__inc_addr_samples() barfs on:
>
> if (addr < sym->start || addr >= sym->end) {
> ...
> return -ERANGE;
>
> Seems like we have 3 bugs here:
...
>
> 3. Why do we have zero length symbols in the first place? Does the recent
> ppc64 exception clean up have something to do with it?
Seems likely. But I can't see why.
AFAICS we have never emitted a size for those symbols:
Old:
$ nm --print-size build/vmlinux | grep -w system_call_relon_pSeries
c000000000004c00 T system_call_relon_pSeries
New:
$ nm --print-size build/vmlinux | grep -w exc_virt_0x4c00_system_call
c000000000004c00 T exc_virt_0x4c00_system_call
It also doesn't look like we're emitting another symbol with the same
address, which has caused confusion in the past:
Old:
c000000000004c00 T exc_virt_0x4c00_system_call
c000000000004d00 T exc_virt_0x4d00_single_step
New:
c000000000004c00 T system_call_relon_pSeries
c000000000004d00 T single_step_relon_pSeries
So more digging required.
cheers
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