From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Milian Wolff <milian.wolff@kdab.com>
Cc: jolsa@kernel.org, Linux-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH] perf util: take pgoff into account when reporting elf to libdwfl
Date: Mon, 29 Oct 2018 14:40:14 -0300 [thread overview]
Message-ID: <20181029174014.GG21857@kernel.org> (raw)
In-Reply-To: <3361238.noN1Jb7VD2@milian-kdab2>
Em Mon, Oct 29, 2018 at 04:26:27PM +0100, Milian Wolff escreveu:
> On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote:
> > Libdwfl parses an ELF file itself and creates mappings for the
> > individual sections. Perf on the other hand sees raw mmap events which
> > represent individual sections. When we encounter an address pointing
> > into a mapping with pgoff != 0, we must take that into account and
> > report the file at the non-offset base address.
> >
> > This fixes unwinding with libdwfl in some cases. E.g. for a file like:
>
> <snip>
>
> > Note that the backtrace is still stopping too early, when
> > compared to the nice results obtained via libunwind. It's
> > unclear so far what the reason for that is.
>
> The remaining issue is due to a bug in elfutils:
>
> https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html
>
> With both patches applied, libunwind and elfutils produce the same output for
> the above scenario.
I'm updating the patch to remove:
"It's unclear so far what the reason for that is."
Adding:
"See https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html for
a patch fixing that."
Ok? Or are you saying that that "unclear" part applies to both libunwind
and elfutils?
- Arnaldo
next prev parent reply other threads:[~2018-10-29 17:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-29 14:16 [PATCH] perf util: take pgoff into account when reporting elf to libdwfl Milian Wolff
2018-10-29 14:56 ` Jiri Olsa
2018-10-29 15:26 ` Milian Wolff
2018-10-29 17:40 ` Arnaldo Carvalho de Melo [this message]
2018-10-30 20:36 ` Milian Wolff
2018-10-31 22:04 ` [tip:perf/urgent] perf unwind: Take " tip-bot for Milian Wolff
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