linux-kernel - Re: [BUG] perf report: fails to symbolize when vaddr is non zero for shared objects

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Message-ID: <20150617192404.GD2368@redhat.com>
Date:	Wed, 17 Jun 2015 16:24:04 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	David Ahern <dsahern@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>
Subject: Re: [BUG] perf report: fails to symbolize when vaddr is non zero for
 shared objects

Em Wed, Jun 17, 2015 at 11:54:12AM -0700, Stephane Eranian escreveu:
> On Tue, Jun 16, 2015 at 7:34 AM, Arnaldo Carvalho de Melo <acme@...hat.com> wrote:
> > Em Tue, Jun 16, 2015 at 12:03:01AM -0700, Stephane Eranian escreveu:
> >> If you get samples in the shared lib, they will be off, possibly
> >> attributed to the wrong
> >> functions.
> >>
> >> Could this be fixed quickly?
> >
> > You tell me, do you have a patch to propose? :-)

> Well, need to make sure I understand the code flow in dso__load_sym()
> and callers.

> You have elf_read_maps() which seems to be reading the phdr but, it
> would need to be called systematically for ET_DYN. I will experiment
> with this.

> Worst case, we need to add another function to read the phdr and use
> the p_vaddr.

Ok, that symbols* code grew unwieldly complex, need to give it some love and
refactoring care at some point...

Thanks!

- Arnaldo
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