From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Qais Yousef <qais.yousef@arm.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: BTFIDS: FAILED unresolved symbol udp6_sock
Date: Sat, 2 Jan 2021 14:25:34 -0800 [thread overview]
Message-ID: <CAEf4BzYbeQqzK2n9oz6wqysVj35k+VZC7DZrXFEtjUM6eiyvOA@mail.gmail.com> (raw)
In-Reply-To: <20201230132759.GB577428@krava>
On Wed, Dec 30, 2020 at 5:28 AM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Wed, Dec 30, 2020 at 10:03:37AM +0100, Jiri Olsa wrote:
> > On Tue, Dec 29, 2020 at 11:28:35PM +0000, Qais Yousef wrote:
> > > Hi Jiri
> > >
> > > On 12/29/20 18:34, Jiri Olsa wrote:
> > > > On Tue, Dec 29, 2020 at 03:13:52PM +0000, Qais Yousef wrote:
> > > > > Hi
> > > > >
> > > > > When I enable CONFIG_DEBUG_INFO_BTF I get the following error in the BTFIDS
> > > > > stage
> > > > >
> > > > > FAILED unresolved symbol udp6_sock
> > > > >
> > > > > I cross compile for arm64. My .config is attached.
> > > > >
> > > > > I managed to reproduce the problem on v5.9 and v5.10. Plus 5.11-rc1.
> > > > >
> > > > > Have you seen this before? I couldn't find a specific report about this
> > > > > problem.
> > > > >
> > > > > Let me know if you need more info.
> > > >
> > > > hi,
> > > > this looks like symptom of the gcc DWARF bug we were
> > > > dealing with recently:
> > > >
> > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060
> > > > https://lore.kernel.org/lkml/CAE1WUT75gu9G62Q9uAALGN6vLX=o7vZ9uhqtVWnbUV81DgmFPw@mail.gmail.com/#r
> > > >
> > > > what pahole/gcc version are you using?
> > >
> > > I'm on gcc 9.3.0
> > >
> > > aarch64-linux-gnu-gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
> > >
> > > I was on pahole v1.17. I moved to v1.19 but I still see the same problem.
> >
> > I can reproduce with your .config, but make 'defconfig' works,
> > so I guess it's some config option issue, I'll check later today
>
> so your .config has
> CONFIG_CRYPTO_DEV_BCM_SPU=y
>
> and that defines 'struct device_private' which
> clashes with the same struct defined in drivers/base/base.h
>
> so several networking structs will be doubled, like net_device:
>
> $ bpftool btf dump file ../vmlinux.config | grep net_device\' | grep STRUCT
> [2731] STRUCT 'net_device' size=2240 vlen=133
> [113981] STRUCT 'net_device' size=2240 vlen=133
>
> each is using different 'struct device_private' when it's unwinded
>
> and that will confuse BTFIDS logic, becase we have multiple structs
> with the same name, and we can't be sure which one to pick
>
> perhaps we should check on this in pahole and warn earlier with
> better error message.. I'll check, but I'm not sure if pahole can
> survive another hastab ;-)
>
> Andrii, any ideas on this? ;-)
It's both unavoidable and correct from the C type system's
perspective, so there is nothing for pahole to warn about. We used to
have (for a long time) a similar clash with two completely different
ring_buffer structs. Eventually they just got renamed to avoid
duplication of related structs (task_struct and tons of other). But
both BTF dedup and CO-RE relocation algorithms are designed to handle
this correctly, so perhaps BTFIDS should be able to handle this as
well?
>
> easy fix is the patch below that renames the bcm's structs,
> it makes the kernel to compile.. but of course the new name
> is probably wrong and we should push this through that code
> authors
In this case, I think renaming generic device_private name is a good
thing regardless.
>
> jirka
>
>
> ---
[...]
next prev parent reply other threads:[~2021-01-02 22:26 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 15:13 BTFIDS: FAILED unresolved symbol udp6_sock Qais Yousef
2020-12-29 17:34 ` Jiri Olsa
2020-12-29 23:28 ` Qais Yousef
2020-12-30 9:03 ` Jiri Olsa
2020-12-30 13:27 ` Jiri Olsa
2020-12-30 13:28 ` Jiri Olsa
2020-12-30 14:19 ` Arnaldo Carvalho de Melo
2020-12-30 15:04 ` Jiri Olsa
2020-12-30 15:29 ` Qais Yousef
2021-01-02 22:25 ` Andrii Nakryiko [this message]
2021-01-02 23:06 ` Jiri Olsa
2021-01-04 20:54 ` Andrii Nakryiko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAEf4BzYbeQqzK2n9oz6wqysVj35k+VZC7DZrXFEtjUM6eiyvOA@mail.gmail.com \
--to=andrii.nakryiko@gmail.com \
--cc=acme@kernel.org \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=jolsa@kernel.org \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=qais.yousef@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.