Re: [PATCH v3 0/2] Kbuild: DWARF v5 support

From: Sedat Dilek <sedat.dilek@gmail.com>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Yonghong Song <yhs@fb.com>, Jiri Olsa <jolsa@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Caroline Tice <cmtice@google.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Jakub Jelinek <jakub@redhat.com>,
	Fangrui Song <maskray@google.com>,
	Clang-Built-Linux ML <clang-built-linux@googlegroups.com>,
	Nick Clifton <nickc@redhat.com>, bpf <bpf@vger.kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>
Subject: Re: [PATCH v3 0/2] Kbuild: DWARF v5 support
Date: Thu, 14 Jan 2021 21:12:51 +0100	[thread overview]
Message-ID: <CA+icZUWUJzG1XcFosgDHmyCaWdCwk8hT8xedQMW66k9Y39YbMA@mail.gmail.com> (raw)
In-Reply-To: <CAKwvOdnZW03GaEbSC0Hpg1wb-mniAbT2gBeCwB66+RYAdSr=7Q@mail.gmail.com>

On Thu, Jan 14, 2021 at 8:20 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Jan 14, 2021 at 11:13 AM Yonghong Song <yhs@fb.com> wrote:
> >
> >
> >
> > On 1/14/21 11:01 AM, Nick Desaulniers wrote:
> > > On Thu, Jan 14, 2021 at 10:53 AM Nick Desaulniers
> > > <ndesaulniers@google.com> wrote:
> > >>
> > >> On Wed, Jan 13, 2021 at 10:18 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>>
> > >>> On Wed, Jan 13, 2021 at 11:25 PM Caroline Tice <cmtice@google.com> wrote:
> > >>>>
> > >>>> On Tue, Jan 12, 2021 at 3:17 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> > >>>>>
> > >>>>> Unfortunately, I see with CONFIG_DEBUG_INFO_DWARF5=y and
> > >>>>> CONFIG_DEBUG_INFO_BTF=y:
> > >>>>>
> > >>>>> die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x3f0dd5a> not handled!
> > >>>>> die__process_function: DW_TAG_INVALID (0x48) @ <0x3f0dd69> not handled!
> > >>
> > >> I can confirm that I see a stream of these warnings when building with
> > >> this patch series applied, and those two configs enabled.
> > >>
> > >> rebuilding with `make ... V=1`, it looks like the call to:
> > >>
> > >> + pahole -J .tmp_vmlinux.btf
> > >>
> > >> is triggering these.
> > >>
> > >> Shall I send a v4 that adds a Kconfig dependency on !DEBUG_INFO_BTF?
> > >> Does pahole have a bug tracker?
> >
> > pahole could have issues for dwarf5 since as far as I know, people just
> > use dwarf2/dwarf4 with config functions in the kernel.
> >
> > Where is the link of the patch to add CONFIG_DEBUG_INFO_DWARF5 to linux?
>
> Latest is v4: https://lore.kernel.org/lkml/20210113003235.716547-1-ndesaulniers@google.com/
>
> > I think you can add CONFIG_DEBUG_INFO_DWARF5 to kernel with dependency
> > of !CONFIG_DEBUG_INFO_BTF. At the same time, people can debug pahole
> > issues. Once it is resolved, !CONFIG_DEBUG_INFO_BTF dependency can be
> > removed with proper pahole version change in kernel.
>
> SGTM, will send a v5 tomorrow in case there's more feedback.
>

Please CC me on v5.

Feel free to add my Reported-by.

- Sedat -

> >
> > >
> > > FWIW, my distro packages pahole v1.17; rebuilt with ToT v1.19 from
> > > source and also observe the issue.
> > >
> --
> Thanks,
> ~Nick Desaulniers