From: Arnaldo Carvalho de Melo <acme@kernel.org>
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>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: BTFIDS: FAILED unresolved symbol udp6_sock
Date: Wed, 30 Dec 2020 11:19:36 -0300 [thread overview]
Message-ID: <20201230141936.GA3922432@kernel.org> (raw)
In-Reply-To: <20201230132852.GC577428@krava>
Em Wed, Dec 30, 2020 at 02:28:52PM +0100, Jiri Olsa escreveu:
> On Wed, Dec 30, 2020 at 02:28:02PM +0100, Jiri Olsa 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.
There are some changes post v1.19 in the git repo:
[acme@five pahole]$ git log --oneline v1.19..
b688e35970600c15 (HEAD -> master) btf_encoder: fix skipping per-CPU variables at offset 0
8c009d6ce762dfc9 btf_encoder: fix BTF variable generation for kernel modules
b94e97e015a94e6b dwarves: Fix compilation on 32-bit architectures
17df51c700248f02 btf_encoder: Detect kernel module ftrace addresses
06ca639505fc56c6 btf_encoder: Use address size based on ELF's class
aff60970d16b909e btf_encoder: Factor filter_functions function
1e6a3fed6e52d365 (quaco/master) rpm: Fix changelog date
[acme@five pahole]$
But I think these won't matter in this case :-\
- Arnaldo
> > > 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? ;-)
> >
> > 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
>
> also another quick fix is to switch it to module
>
> jirka
>
--
- Arnaldo
next prev parent reply other threads:[~2020-12-30 14:20 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 [this message]
2020-12-30 15:04 ` Jiri Olsa
2020-12-30 15:29 ` Qais Yousef
2021-01-02 22:25 ` Andrii Nakryiko
2021-01-02 23:06 ` Jiri Olsa
2021-01-04 20:54 ` Andrii Nakryiko
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