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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Andrii Nakryiko <andriin@fb.com>
Cc: bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
	Alexei Starovoitov <ast@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Yonghong Song <yhs@fb.com>, Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 01/10] libbpf: add .BTF.ext offset relocation section loading
Date: Wed, 24 Jul 2019 14:42:25 -0700	[thread overview]
Message-ID: <CAEf4Bzbrm0mrteuK=jFs6gdfLceMkjLDJ=UhOg1x8JeRfai07A@mail.gmail.com> (raw)
In-Reply-To: <20190724192742.1419254-2-andriin@fb.com>

On Wed, Jul 24, 2019 at 12:28 PM Andrii Nakryiko <andriin@fb.com> wrote:
>
> Add support for BPF CO-RE offset relocations. Add section/record
> iteration macros for .BTF.ext. These macro are useful for iterating over
> each .BTF.ext record, either for dumping out contents or later for BPF
> CO-RE relocation handling.
>
> To enable other parts of libbpf to work with .BTF.ext contents, moved
> a bunch of type definitions into libbpf_internal.h.
>
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> ---

[...]

> + *
> + * Example to provide a better feel.
> + *
> + *   struct sample {
> + *       int a;
> + *       struct {
> + *           int b[10];
> + *       };
> + *   };
> + *
> + *   struct sample *s = ...;
> + *   int x = &s->a;     // encoded as "0:0" (a is field #0)
> + *   int y = &s->b[5];  // encoded as "0:1:5" (b is field #1, arr elem #5)

This should be "0:1:0:5", actually. Anon struct is field #1 in BTF, b
is field #0 inside that anon struct + array index 5.
Will update it locally and incorporate into next version once the rest
of patch set is reviewed.

> + *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
> + *
> + * type_id for all relocs in this example  will capture BTF type id of
> + * `struct sample`.
> + *
> + *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
> + */
> +struct bpf_offset_reloc {
> +       __u32   insn_off;
> +       __u32   type_id;
> +       __u32   access_str_off;
> +};
> +
>  #endif /* __LIBBPF_LIBBPF_INTERNAL_H */
> --
> 2.17.1
>

  reply	other threads:[~2019-07-24 21:42 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-24 19:27 [PATCH bpf-next 00/10] CO-RE offset relocations Andrii Nakryiko
2019-07-24 19:27 ` [PATCH bpf-next 01/10] libbpf: add .BTF.ext offset relocation section loading Andrii Nakryiko
2019-07-24 21:42   ` Andrii Nakryiko [this message]
2019-07-25  0:00   ` Song Liu
2019-07-25  0:37     ` Andrii Nakryiko
2019-07-25  5:20       ` Song Liu
2019-07-27  5:11         ` Andrii Nakryiko
2019-07-29 20:00           ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 02/10] libbpf: implement BPF CO-RE offset relocation algorithm Andrii Nakryiko
2019-07-25 19:32   ` Song Liu
2019-07-27  6:11     ` Andrii Nakryiko
2019-07-27 18:59       ` Song Liu
2019-07-27 19:09         ` Andrii Nakryiko
2019-07-28  0:24           ` Song Liu
2019-07-25 23:18   ` Alexei Starovoitov
2019-07-27  6:25     ` Andrii Nakryiko
2019-07-27 17:00       ` Alexei Starovoitov
2019-07-27 18:24         ` Andrii Nakryiko
2019-07-27 21:29           ` Yonghong Song
2019-07-27 21:36             ` Andrii Nakryiko
2019-07-29 19:56   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 03/10] selftests/bpf: add CO-RE relocs testing setup Andrii Nakryiko
2019-07-29 20:22   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 04/10] selftests/bpf: add CO-RE relocs struct flavors tests Andrii Nakryiko
2019-07-29 20:37   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 05/10] selftests/bpf: add CO-RE relocs nesting tests Andrii Nakryiko
2019-07-29 21:06   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 06/10] selftests/bpf: add CO-RE relocs array tests Andrii Nakryiko
2019-07-25 23:26   ` Alexei Starovoitov
2019-07-26 23:29     ` Andrii Nakryiko
2019-07-24 19:27 ` [PATCH bpf-next 07/10] selftests/bpf: add CO-RE relocs enum/ptr/func_proto tests Andrii Nakryiko
2019-07-29 21:09   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 08/10] selftests/bpf: add CO-RE relocs modifiers/typedef tests Andrii Nakryiko
2019-07-29 21:11   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 09/10] selftest/bpf: add CO-RE relocs ptr-as-array tests Andrii Nakryiko
2019-07-29 21:14   ` Song Liu
2019-07-24 19:27 ` [PATCH bpf-next 10/10] selftests/bpf: add CO-RE relocs ints tests Andrii Nakryiko
2019-07-29 21:21   ` Song Liu
2019-07-29 20:20 ` [PATCH bpf-next 00/10] CO-RE offset relocations Song Liu
2019-07-29 20:36   ` Song Liu
2019-07-29 23:09     ` Andrii Nakryiko
2019-07-30  5:27       ` Song Liu

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