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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next v4 16/18] selftests/bpf: Add a test for enum64 value relocations
Date: Sat, 4 Jun 2022 11:34:34 +0200	[thread overview]
Message-ID: <CAADnVQKxkY2+guT8BD4+3JQarJ+iwHiegLiD9bMAT=MAaMw9OA@mail.gmail.com> (raw)
In-Reply-To: <dfbe2c95-b6d7-1e26-4c3d-9ae7513235d0@fb.com>

On Sat, Jun 4, 2022 at 4:51 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 6/3/22 8:14 AM, Alexei Starovoitov wrote:
> > On Fri, Jun 3, 2022 at 4:00 AM Yonghong Song <yhs@fb.com> wrote:
> >> +
> >> +SEC("raw_tracepoint/sys_enter")
> >> +int test_core_enum64val(void *ctx)
> >> +{
> >> +#if __has_builtin(__builtin_preserve_enum_value)
> >> +       struct core_reloc_enum64val_output *out = (void *)&data.out;
> >> +       enum named_unsigned_enum64 named_unsigned = 0;
> >> +       enum named_signed_enum64 named_signed = 0;
> >
> > libbpf: prog 'test_core_enum64val': relo #0: unexpected insn #0
> > (LDIMM64) value: got 8589934591, exp 18446744073709551615 ->
> > 18446744073709551615
> > libbpf: prog 'test_core_enum64val': relo #0: failed to patch insn #0: -22
> > libbpf: failed to perform CO-RE relocations: -22
> > libbpf: failed to load object 'test_core_reloc_enum64val.o'
> >
> > Is it failing in CI because clang is too old?
>
> Yes, the failure is due to that the llvm patch to support enum64
> is not merged. The llvm patch is not merged because otherwise
> people using latest compiler (with llvm patch) may fail to
> latest libbpf.
>
> > CI will pick up newer clang sooner or later,
> > but the users will be confused.
> > The patch 17/18 that updates README certainly helps,
> > but I was wondering whether we can do a similar trick
> > to what Andrii did in libbpf and make the error more human readable?
>
> I think the above information is what current libbpf did for
> relocation errors.
>
> Unless I missed something, Andrii's commit 9fdc4273b8da ("libbpf: Fix up
> verifier log for unguarded failed CO-RE relos") is to improve kernel
> verifier log w.r.t. relocation failures.

Right. I was referring to the spirit of that commit.
libbpf can probably print more user friendly message and point out
that enum64 is potentially missing in the clang?

  reply	other threads:[~2022-06-04  9:34 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-03  1:58 [PATCH bpf-next v4 00/18] bpf: Add 64bit enum value support Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 01/18] bpf: Add btf enum64 support Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 02/18] libbpf: Permit 64bit relocation value Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 03/18] libbpf: Fix an error in 64bit relocation value computation Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 04/18] libbpf: Refactor btf__add_enum() for future code sharing Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 05/18] libbpf: Add enum64 parsing and new enum64 public API Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 06/18] libbpf: Add enum64 deduplication support Yonghong Song
2022-06-03 21:44   ` Andrii Nakryiko
2022-06-03  1:59 ` [PATCH bpf-next v4 07/18] libbpf: Add enum64 support for btf_dump Yonghong Song
2022-06-03 21:46   ` Andrii Nakryiko
2022-06-03  1:59 ` [PATCH bpf-next v4 08/18] libbpf: Add enum64 sanitization Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 09/18] libbpf: Add enum64 support for bpf linking Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 10/18] libbpf: Add enum64 relocation support Yonghong Song
2022-06-03 21:49   ` Andrii Nakryiko
2022-06-03  1:59 ` [PATCH bpf-next v4 11/18] bpftool: Add btf enum64 support Yonghong Song
2022-06-03  1:59 ` [PATCH bpf-next v4 12/18] selftests/bpf: Fix selftests failure Yonghong Song
2022-06-03  2:00 ` [PATCH bpf-next v4 13/18] selftests/bpf: Test new enum kflag and enum64 API functions Yonghong Song
2022-06-03  2:00 ` [PATCH bpf-next v4 14/18] selftests/bpf: Add BTF_KIND_ENUM64 unit tests Yonghong Song
2022-06-03  2:00 ` [PATCH bpf-next v4 15/18] selftests/bpf: Test BTF_KIND_ENUM64 for deduplication Yonghong Song
2022-06-03  2:00 ` [PATCH bpf-next v4 16/18] selftests/bpf: Add a test for enum64 value relocations Yonghong Song
2022-06-03 15:14   ` Alexei Starovoitov
2022-06-03 20:22     ` Andrii Nakryiko
2022-06-03 20:24       ` Andrii Nakryiko
2022-06-04  2:51     ` Yonghong Song
2022-06-04  9:34       ` Alexei Starovoitov [this message]
2022-06-03  2:00 ` [PATCH bpf-next v4 17/18] selftests/bpf: Clarify llvm dependency with possible selftest failures Yonghong Song
2022-06-03  2:00 ` [PATCH bpf-next v4 18/18] docs/bpf: Update documentation for BTF_KIND_ENUM64 support Yonghong Song

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