Date: Mon, 21 Nov 2016 17:28:18 +1100
From: Anton Blanchard <anton@samba.org>
To: Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>, Nicholas Piggin <npiggin@gmail.com>,
        ravi.bangoria@linux.vnet.ibm.com, acme@redhat.com,
        peterz@infradead.org, mingo@redhat.com,
        alexander.shishkin@linux.intel.com
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.orgp
Subject: Re: perf TUI fails with "failed to process type: 64"
Message-ID: <20161121172818.161639c2@kryten>
In-Reply-To: <20161009121232.174915eb@kryten>
References: <20161009121232.174915eb@kryten>
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Hi,

I forgot about the set of issues below. Michael had a suggested powerpc
fix for 3, but it it would be nice to fix the perf bugs in 1 and 2.

Anton
--

> 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
> 
> 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:
> 
> 1. Output the real source of the error instead of
> PERF_RECORD_FINISHED_ROUND
> 
> 2. Don't exit the TUI if we find a sample on a zero length symbol
> 
> 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?
> 
> Anton