linux-kernel - Re: [PATCH v2] perf callchain: fix kernel symbol resolution by remembering the cpumode

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Date:	Mon, 30 Mar 2015 10:54:34 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	David Hildenbrand <dahi@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, a.p.zijlstra@...llo.nl,
	paulus@...ba.org, mingo@...hat.com, acme@...nel.org,
	acme@...hat.com, jolsa@...nel.org, kan.liang@...el.com,
	namhyung@...nel.org, adrian.hunter@...el.com, ak@...ux.intel.com,
	brueckner@...ux.vnet.ibm.com, schwidefsky@...ibm.com
Subject: Re: [PATCH v2] perf callchain: fix kernel symbol resolution by
 remembering the cpumode

On Mon, Mar 30, 2015 at 10:11:00AM +0200, David Hildenbrand wrote:
> Commit 2e77784bb7d8 ("perf callchain: Move cpumode resolve code to
> add_callchain_ip") promised "No change in behavior.".
> 
> As this commit breaks callchains on s390x (symbols not getting resolved,

I think it's a generic problem not just s390x

the x86 archs were safe due to the (al->map == NULL) fallback
in thread__find_addr_map, where we rerun the lookup for kernel
maps.. I need to rethink this check :-\

perhaps s390x did not match the machine__kernel_ip condition?


> observed when profiling the kernel), this statement is wrong. The cpumode
> must be kept when iterating over all ips, otherwise the default
> (PERF_RECORD_MISC_USER) will be used by error.

anyway

Acked-by: Jiri Olsa <jolsa@...nel.org>


thanks,
jirka
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