From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Alexandre Ghiti <alexandre@ghiti.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Networking <netdev@vger.kernel.org>,
Linux Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
ppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-arm-kernel@lists.infradead.org, zong.li@sifive.com,
Andrii Nakryiko <andrii.nakryiko@gmail.com>
Subject: Re: Re: linux-next: build warning after merge of the bpf-next tree
Date: Fri, 10 Jan 2020 15:18:50 -0800 [thread overview]
Message-ID: <CAADnVQLo5HEjTpTTRm=BtExuKifPtCJm+Hu_WP6yeyV-Er55Qg@mail.gmail.com> (raw)
In-Reply-To: <a367af4d-7267-2e94-74dc-2a2aac204080@ghiti.fr>
On Fri, Jan 10, 2020 at 2:28 PM Alexandre Ghiti <alexandre@ghiti.fr> wrote:
>
> Hi guys,
>
> On 10/27/19 8:02 PM, Stephen Rothwell wrote:
> > Hi all,
> >
> > On Fri, 18 Oct 2019 10:56:57 +1100 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >> Hi all,
> >>
> >> After merging the bpf-next tree, today's linux-next build (powerpc
> >> ppc64_defconfig) produced this warning:
> >>
> >> WARNING: 2 bad relocations
> >> c000000001998a48 R_PPC64_ADDR64 _binary__btf_vmlinux_bin_start
> >> c000000001998a50 R_PPC64_ADDR64 _binary__btf_vmlinux_bin_end
> >>
> >> Introduced by commit
> >>
> >> 8580ac9404f6 ("bpf: Process in-kernel BTF")
> > This warning now appears in the net-next tree build.
> >
> >
> I bump that thread up because Zong also noticed that 2 new relocations for
> those symbols appeared in my riscv relocatable kernel branch following
> that commit.
>
> I also noticed 2 new relocations R_AARCH64_ABS64 appearing in arm64 kernel.
>
> Those 2 weak undefined symbols have existed since commit
> 341dfcf8d78e ("btf: expose BTF info through sysfs") but this is the fact
> to declare those symbols into btf.c that produced those relocations.
>
> I'm not sure what this all means, but this is not something I expected
> for riscv for
> a kernel linked with -shared/-fpie. Maybe should we just leave them to
> zero ?
>
> I think that deserves a deeper look if someone understands all this
> better than I do.
Are you saying there is a warning for arm64 as well?
Can ppc folks explain the above warning?
What does it mean "2 bad relocations"?
The code is doing:
extern char __weak _binary__btf_vmlinux_bin_start[];
extern char __weak _binary__btf_vmlinux_bin_end[];
Since they are weak they should be zero when not defined.
What's the issue?
next prev parent reply other threads:[~2020-01-10 23:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 23:56 linux-next: build warning after merge of the bpf-next tree Stephen Rothwell
2019-10-18 5:01 ` Alexei Starovoitov
2019-10-28 0:02 ` Stephen Rothwell
2020-01-10 22:28 ` Alexandre Ghiti
2020-01-10 23:18 ` Alexei Starovoitov [this message]
2020-01-11 14:06 ` Alexandre Ghiti
2020-01-11 0:20 ` Palmer Dabbelt
2020-01-11 14:31 ` Alexandre Ghiti
2020-01-13 4:33 ` Zong Li
2020-01-14 5:23 ` Alexei Starovoitov
2020-01-15 20:48 ` Alexandre Ghiti
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