From: Sedat Dilek <sedat.dilek@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
Tom Stellard <tstellar@redhat.com>, Jiri Olsa <jolsa@kernel.org>,
dwarves@vger.kernel.org, bpf <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andriin@fb.com>, Yonghong Song <yhs@fb.com>,
Hao Luo <haoluo@google.com>
Subject: Re: [PATCH] btf_encoder: Add extra checks for symbol names
Date: Fri, 22 Jan 2021 03:07:25 +0100 [thread overview]
Message-ID: <CA+icZUW6g9=sMD3hj5g+ZXOwE_DxfxO3SX2Tb-bFTiWnQLb_EA@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzaVAp=W47KmMsfpj_wuJR-Gvmav=tdKdoHKAC3AW-976w@mail.gmail.com>
On Thu, Jan 21, 2021 at 9:53 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Jan 21, 2021 at 8:09 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Thu, Jan 21, 2021 at 2:38 PM Arnaldo Carvalho de Melo
> > <arnaldo.melo@gmail.com> wrote:
> > >
> > > Em Tue, Jan 12, 2021 at 04:27:59PM -0800, Tom Stellard escreveu:
> > > > On 1/12/21 10:40 AM, Jiri Olsa wrote:
> > > > > When processing kernel image build by clang we can
> > > > > find some functions without the name, which causes
> > > > > pahole to segfault.
> > > > >
> > > > > Adding extra checks to make sure we always have
> > > > > function's name defined before using it.
> > > > >
> > > >
> > > > I backported this patch to pahole 1.19, and I can confirm it fixes the
> > > > segfault for me.
> > >
> > > I'm applying v2 for this patch and based on your above statement I'm
> > > adding a:
> > >
> > > Tested-by: Tom Stellard <tstellar@redhat.com>
> > >
> > > Ok?
> > >
> > > Who originally reported this?
> > >
> >
> > The origin was AFAICS the thread where I asked initially [1].
> >
> > Tom reported in the same thread in [2] that pahole segfaults.
> >
> > Later in the thread Jiri offered a draft of this patch after doing some tests.
> >
> > I have tested all diffs and v1 and v2 of Jiri's patch.
> > ( Anyway, latest pahole ToT plus Jiri's patch did not solve my origin problem. )
>
> Your original problem was with DWARF5 or DWARF4? I think you mentioned
> both at some point, but I remember I couldn't repro DWARF4 problems.
> If you still have problems, can you start a new thread with steps to
> repro (including Kconfig, tooling versions, etc). And one for each
> problem, no all at the same time, please. I honestly lost track of
> what's still not working among those multiple intertwined email
> threads, sorry about that.
>
I love people saying "I have a (one) problem." :-).
The origin was Debian kernel-team enabled BTF-debuginfo Kconfig.
My main focus is to be as close to Debian's kernel-config and if this
works well with (experimental) Linux DWARF v5 support I am a happy
guy.
Do you want Nick's DWARF v5 patch-series as a base?
Thinking of DWARF-v4?
Use Nick's patchset or DWARF-v4 what is in Linux upstream means Linux
v5.11-rc4+?
What Git tree to use - Linus or one of your BPF/BTF folks?
What version of pahole (latest Git) etc.?
- Sedat -
> >
> > So up to you Arnaldo for the credits.
> >
> > - Sedat -
> >
> > [1] https://marc.info/?t=161036949500004&r=1&w=2
> > [2] https://marc.info/?t=161036949500004&r=1&w=2
> >
> > > - Arnaldo
> > >
> > > > -Tom
> > > >
> > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > > > > ---
> > > > > btf_encoder.c | 8 ++++++--
> > > > > 1 file changed, 6 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/btf_encoder.c b/btf_encoder.c
> > > > > index 333973054b61..17f7a14f2ef0 100644
> > > > > --- a/btf_encoder.c
> > > > > +++ b/btf_encoder.c
> > > > > @@ -72,6 +72,8 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym)
> > > > > if (elf_sym__type(sym) != STT_FUNC)
> > > > > return 0;
> > > > > + if (!elf_sym__name(sym, btfe->symtab))
> > > > > + return 0;
> > > > > if (functions_cnt == functions_alloc) {
> > > > > functions_alloc = max(1000, functions_alloc * 3 / 2);
> > > > > @@ -730,9 +732,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force,
> > > > > if (!has_arg_names(cu, &fn->proto))
> > > > > continue;
> > > > > if (functions_cnt) {
> > > > > - struct elf_function *func;
> > > > > + const char *name = function__name(fn, cu);
> > > > > + struct elf_function *func = NULL;
> > > > > - func = find_function(btfe, function__name(fn, cu));
> > > > > + if (name)
> > > > > + func = find_function(btfe, name);
> > > > > if (!func || func->generated)
> > > > > continue;
> > > > > func->generated = true;
> > > > >
> > > >
> > >
> > > --
> > >
> > > - Arnaldo
next prev parent reply other threads:[~2021-01-22 2:08 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 18:40 [PATCH] btf_encoder: Add extra checks for symbol names Jiri Olsa
2021-01-12 19:20 ` Andrii Nakryiko
2021-01-12 19:47 ` Jiri Olsa
2021-01-12 20:17 ` Sedat Dilek
2021-01-13 0:27 ` Tom Stellard
2021-01-14 7:50 ` Sedat Dilek
2021-01-14 14:33 ` Tom Stellard
2021-01-14 14:39 ` Sedat Dilek
2021-01-21 13:38 ` Arnaldo Carvalho de Melo
2021-01-21 16:06 ` Sedat Dilek
2021-01-21 19:37 ` Arnaldo Carvalho de Melo
2021-01-21 20:53 ` Andrii Nakryiko
2021-01-22 2:07 ` Sedat Dilek [this message]
2021-01-22 4:11 ` Andrii Nakryiko
2021-01-28 20:00 ` [RFT] pahole 1.20 RC was " Arnaldo Carvalho de Melo
2021-01-28 20:57 ` Sedat Dilek
2021-01-28 21:11 ` Arnaldo Carvalho de Melo
2021-01-28 22:28 ` Sedat Dilek
2021-02-02 7:48 ` Andrii Nakryiko
2021-02-03 9:03 ` Sedat Dilek
2021-02-03 10:23 ` Mark Wielaard
2021-02-03 21:48 ` Sedat Dilek
2021-02-03 23:21 ` Andrii Nakryiko
2021-02-04 1:06 ` Arnaldo Carvalho de Melo
2021-02-04 6:40 ` Sedat Dilek
2021-01-21 17:37 ` Tom Stellard
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