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From: Namhyung Kim <namhyung@kernel.org>
Date: Wed, 7 Feb 2024 12:43:14 -0800
Message-ID: <CAM9d7ciK5XVBCuaSmTPkqMGaK=rqA1xKpE8VOqZh9V_tYEb5pw@mail.gmail.com>
Subject: Re: [PATCH 04/14] perf map: Add map__objdump_2rip()
To: Ian Rogers <irogers@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@kernel.org>, 
	Adrian Hunter <adrian.hunter@intel.com>, Peter Zijlstra <peterz@infradead.org>, 
	Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>, 
	linux-perf-users@vger.kernel.org, 
	Linus Torvalds <torvalds@linux-foundation.org>, Stephane Eranian <eranian@google.com>, 
	Masami Hiramatsu <mhiramat@kernel.org>, linux-toolchains@vger.kernel.org, 
	linux-trace-devel@vger.kernel.org
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On Wed, Feb 7, 2024 at 11:56=E2=80=AFAM Ian Rogers <irogers@google.com> wro=
te:
>
> On Wed, Feb 7, 2024 at 11:04=E2=80=AFAM Namhyung Kim <namhyung@kernel.org=
> wrote:
> >
> > On Tue, Feb 6, 2024 at 3:34=E2=80=AFPM Ian Rogers <irogers@google.com> =
wrote:
> > >
> > > On Tue, Feb 6, 2024 at 3:04=E2=80=AFPM Namhyung Kim <namhyung@kernel.=
org> wrote:
> > > >
> > > > Hi Ian,
> > > >
> > > > On Fri, Feb 2, 2024 at 5:42=E2=80=AFPM Ian Rogers <irogers@google.c=
om> wrote:
> > > > >
> > > > > On Fri, Feb 2, 2024 at 2:05=E2=80=AFPM Namhyung Kim <namhyung@ker=
nel.org> wrote:
> > > > > >
> > > > > > Sometimes we want to convert an address in objdump output to
> > > > > > map-relative address to match with a sample data.  Let's add
> > > > > > map__objdump_2rip() for that.
> > > > >
> > > > > Hi Namhyung,
> > > > >
> > > > > I think the naming can be better here. Aren't the objdump address=
es
> > > > > DSO relative offsets? Is the relative IP relative to the map or t=
he
> > > > > DSO?
> > > >
> > > > AFAIK the objdump addresses are DSO-relative and rip is to map.
> > > > They are mostly the same but sometimes different due to kASLR
> > > > for the kernel.
> > >
> > > Perhaps we need to use names like map_rip for mapping relative and
> > > dso_rip to clean this up, or to add a different mapping_type to the
> > > enum. For non-kernel maps addresses for map are either the whole
> > > virtual address space (identity) or relative to a dso:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.=
git/tree/tools/perf/util/map.h?h=3Dperf-tools-next#n115
> > > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.=
git/tree/tools/perf/util/map.h?h=3Dperf-tools-next#n20
> > > The dso addresses should work for objdump so perhaps the kernel
> > > addresses need map__pgoff fixing?
> >
> > I'm not sure about the vDSO case.
> >
> > By the way, I need to take a look if we can make this objdump-rip
> > thing simpler as you mentioned.  My feeling is that it can be done
> > but I'd like to do it in a separate work and to move this forward.
>
> Makes sense. Could we add a comment to the header file definition to
> capture some of this? Perhaps a "to be removed" to avoid later patches
> adding dependencies to the function.

Sure, will add that in v6.

Thanks,
Namhyung