From: Alexandre Ghiti <alexandre@ghiti.fr>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Zong Li <zong.li@sifive.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Network Development <netdev@vger.kernel.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>,
ppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: linux-next: build warning after merge of the bpf-next tree
Date: Wed, 15 Jan 2020 15:48:18 -0500 [thread overview]
Message-ID: <6c03d212-775c-cddb-b0d0-d7b00571694b@ghiti.fr> (raw)
In-Reply-To: <CAADnVQ+kbxpw7fxRZodTtE7AmEmRDgO9fcmMD8kKRssS8WJizA@mail.gmail.com>
On 1/14/20 6:23 AM, Alexei Starovoitov wrote:
> On Sun, Jan 12, 2020 at 8:33 PM Zong Li<zong.li@sifive.com> wrote:
>> I'm not quite familiar with btf, so I have no idea why there are two
>> weak symbols be added in 8580ac9404f6 ("bpf: Process in-kernel BTF")
> I can explain what these weak symbols are for, but that won't change
> the fact that compiler or linker are buggy. The weak symbols should work
> in all cases and compiler should pick correct relocation.
> In this case it sounds that compiler picked relative relocation and failed
> to reach zero from that address.
Sorry for the response delay: I now agree that there is nothing weird
about those
relocations. All compiler/linker I took a look at (arm64, ppc64 and
riscv64) correctly
emit an absolute relocation to the address 0 in case of a weak
unresolved symbol,
so there's no buggy compiler/linker.
And regarding ppc warning, the kernel being compiled as -pie, the
scripts looks
for absolute relocations which it considers as "bad", except for one
that is known
to be weak and that is ignored: I have just sent a patch to fix this
script so that weak
undefined symbol relocations are not considered as bad.
Thanks,
Alex
WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Ghiti <alexandre@ghiti.fr>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Zong Li <zong.li@sifive.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Daniel Borkmann <daniel@iogearbox.net>,
Network Development <netdev@vger.kernel.org>,
Palmer Dabbelt <palmerdabbelt@google.com>,
Alexei Starovoitov <ast@kernel.org>,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
ppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: linux-next: build warning after merge of the bpf-next tree
Date: Wed, 15 Jan 2020 15:48:18 -0500 [thread overview]
Message-ID: <6c03d212-775c-cddb-b0d0-d7b00571694b@ghiti.fr> (raw)
In-Reply-To: <CAADnVQ+kbxpw7fxRZodTtE7AmEmRDgO9fcmMD8kKRssS8WJizA@mail.gmail.com>
On 1/14/20 6:23 AM, Alexei Starovoitov wrote:
> On Sun, Jan 12, 2020 at 8:33 PM Zong Li<zong.li@sifive.com> wrote:
>> I'm not quite familiar with btf, so I have no idea why there are two
>> weak symbols be added in 8580ac9404f6 ("bpf: Process in-kernel BTF")
> I can explain what these weak symbols are for, but that won't change
> the fact that compiler or linker are buggy. The weak symbols should work
> in all cases and compiler should pick correct relocation.
> In this case it sounds that compiler picked relative relocation and failed
> to reach zero from that address.
Sorry for the response delay: I now agree that there is nothing weird
about those
relocations. All compiler/linker I took a look at (arm64, ppc64 and
riscv64) correctly
emit an absolute relocation to the address 0 in case of a weak
unresolved symbol,
so there's no buggy compiler/linker.
And regarding ppc warning, the kernel being compiled as -pie, the
scripts looks
for absolute relocations which it considers as "bad", except for one
that is known
to be weak and that is ignored: I have just sent a patch to fix this
script so that weak
undefined symbol relocations are not considered as bad.
Thanks,
Alex
WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Ghiti <alexandre@ghiti.fr>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Zong Li <zong.li@sifive.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Daniel Borkmann <daniel@iogearbox.net>,
Network Development <netdev@vger.kernel.org>,
Palmer Dabbelt <palmerdabbelt@google.com>,
Alexei Starovoitov <ast@kernel.org>,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
ppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: linux-next: build warning after merge of the bpf-next tree
Date: Wed, 15 Jan 2020 15:48:18 -0500 [thread overview]
Message-ID: <6c03d212-775c-cddb-b0d0-d7b00571694b@ghiti.fr> (raw)
In-Reply-To: <CAADnVQ+kbxpw7fxRZodTtE7AmEmRDgO9fcmMD8kKRssS8WJizA@mail.gmail.com>
On 1/14/20 6:23 AM, Alexei Starovoitov wrote:
> On Sun, Jan 12, 2020 at 8:33 PM Zong Li<zong.li@sifive.com> wrote:
>> I'm not quite familiar with btf, so I have no idea why there are two
>> weak symbols be added in 8580ac9404f6 ("bpf: Process in-kernel BTF")
> I can explain what these weak symbols are for, but that won't change
> the fact that compiler or linker are buggy. The weak symbols should work
> in all cases and compiler should pick correct relocation.
> In this case it sounds that compiler picked relative relocation and failed
> to reach zero from that address.
Sorry for the response delay: I now agree that there is nothing weird
about those
relocations. All compiler/linker I took a look at (arm64, ppc64 and
riscv64) correctly
emit an absolute relocation to the address 0 in case of a weak
unresolved symbol,
so there's no buggy compiler/linker.
And regarding ppc warning, the kernel being compiled as -pie, the
scripts looks
for absolute relocations which it considers as "bad", except for one
that is known
to be weak and that is ignored: I have just sent a patch to fix this
script so that weak
undefined symbol relocations are not considered as bad.
Thanks,
Alex
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-01-15 20:48 UTC|newest]
Thread overview: 53+ 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
2019-10-17 23:56 ` Stephen Rothwell
2019-10-18 5:01 ` Alexei Starovoitov
2019-10-18 5:01 ` Alexei Starovoitov
2019-10-28 0:02 ` Stephen Rothwell
2019-10-28 0:02 ` Stephen Rothwell
2020-01-10 22:28 ` Alexandre Ghiti
2020-01-10 22:28 ` Alexandre Ghiti
2020-01-10 22:28 ` Alexandre Ghiti
2020-01-10 23:18 ` Alexei Starovoitov
2020-01-10 23:18 ` Alexei Starovoitov
2020-01-10 23:18 ` Alexei Starovoitov
2020-01-11 14:06 ` Alexandre Ghiti
2020-01-11 14:06 ` Alexandre Ghiti
2020-01-11 14:06 ` Alexandre Ghiti
2020-01-11 0:20 ` Palmer Dabbelt
2020-01-11 0:20 ` Palmer Dabbelt
2020-01-11 0:20 ` Palmer Dabbelt
2020-01-11 14:31 ` Alexandre Ghiti
2020-01-11 14:31 ` Alexandre Ghiti
2020-01-11 14:31 ` Alexandre Ghiti
2020-01-13 4:33 ` Zong Li
2020-01-13 4:33 ` Zong Li
2020-01-13 4:33 ` Zong Li
2020-01-14 5:23 ` Alexei Starovoitov
2020-01-14 5:23 ` Alexei Starovoitov
2020-01-14 5:23 ` Alexei Starovoitov
2020-01-15 20:48 ` Alexandre Ghiti [this message]
2020-01-15 20:48 ` Alexandre Ghiti
2020-01-15 20:48 ` Alexandre Ghiti
-- strict thread matches above, loose matches on Subject: below --
2024-02-06 4:33 Stephen Rothwell
2023-10-13 0:40 Stephen Rothwell
2023-10-13 5:30 ` Stephen Rothwell
2023-10-13 16:54 ` Martin KaFai Lau
2023-02-15 3:45 Stephen Rothwell
2023-02-06 3:54 Stephen Rothwell
2023-02-06 3:59 ` Alexei Starovoitov
2021-12-05 23:55 Stephen Rothwell
2021-12-06 0:43 ` Stephen Rothwell
2021-12-07 3:22 ` Andrii Nakryiko
2020-11-11 1:01 Stephen Rothwell
2020-11-11 14:03 ` Qian Cai
2020-11-11 18:15 ` Andrii Nakryiko
2020-07-14 2:16 Stephen Rothwell
2020-07-14 9:00 ` Jiri Olsa
2020-07-14 9:27 ` Geert Uytterhoeven
2020-07-14 10:33 ` Stephen Rothwell
2020-07-14 10:47 ` Jiri Olsa
2020-07-14 11:15 ` Jiri Olsa
2020-07-14 14:54 ` Alexei Starovoitov
2019-03-24 22:28 Stephen Rothwell
2019-03-24 22:39 ` Willem de Bruijn
2018-05-09 4:49 Stephen Rothwell
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