Received-SPF: pass (google.com: domain of linux-kernel+bounces-56995-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Precedence: bulk
MIME-Version: 1.0
References: <20240202220459.527138-1-namhyung@kernel.org> <20240202220459.527138-5-namhyung@kernel.org>
 <CAP-5=fU=P-ib+n+OfqJAbm8gS2RY-W-KcBskoSHkC+aCmXYcXQ@mail.gmail.com>
 <CAM9d7chvEw6r8_7agxOpWxufTo+dLaNForSFFShCFGd9KDBtoA@mail.gmail.com>
 <CAP-5=fWx9Uub9uRgQJq_ekQScm4fJXMdr9_cr19vcckCPjPt9w@mail.gmail.com> <CAM9d7ciGna7tm5gxoVAQexj_to9sRSL-emmCTSkMbGZgY8mthw@mail.gmail.com>
In-Reply-To: <CAM9d7ciGna7tm5gxoVAQexj_to9sRSL-emmCTSkMbGZgY8mthw@mail.gmail.com>
From: Ian Rogers <irogers@google.com>
Date: Wed, 7 Feb 2024 11:56:13 -0800
Message-ID: <CAP-5=fXWew4c-0zAAny-1R+6mZpfATUc8pEi0G6G79BebiaPuA@mail.gmail.com>
Subject: Re: [PATCH 04/14] perf map: Add map__objdump_2rip()
To: Namhyung Kim <namhyung@kernel.org>
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
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

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> wr=
ote:
> >
> > On Tue, Feb 6, 2024 at 3:04=E2=80=AFPM Namhyung Kim <namhyung@kernel.or=
g> wrote:
> > >
> > > Hi Ian,
> > >
> > > On Fri, Feb 2, 2024 at 5:42=E2=80=AFPM Ian Rogers <irogers@google.com=
> wrote:
> > > >
> > > > On Fri, Feb 2, 2024 at 2:05=E2=80=AFPM Namhyung Kim <namhyung@kerne=
l.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 addresses
> > > > DSO relative offsets? Is the relative IP relative to the map or the
> > > > 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.gi=
t/tree/tools/perf/util/map.h?h=3Dperf-tools-next#n115
> > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.gi=
t/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.

Thanks,
Ian

> Thanks,
> Namhyung