From: Song Liu <songliubraving@fb.com>
To: Andrii Nakryiko <andriin@fb.com>
Cc: bpf <bpf@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"andrii.nakryiko@gmail.com" <andrii.nakryiko@gmail.com>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 4/6] libbpf: add BPF_CORE_READ/BPF_CORE_READ_INTO helpers
Date: Tue, 1 Oct 2019 21:14:15 +0000 [thread overview]
Message-ID: <346DCE18-FA64-40CA-86BD-C095935AC089@fb.com> (raw)
In-Reply-To: <20190930185855.4115372-5-andriin@fb.com>
> On Sep 30, 2019, at 11:58 AM, Andrii Nakryiko <andriin@fb.com> wrote:
>
> Add few macros simplifying BCC-like multi-level probe reads, while also
> emitting CO-RE relocations for each read.
>
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> ---
> tools/lib/bpf/bpf_helpers.h | 151 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 147 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index a1d9b97b8e15..51e7b11d53e8 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -19,6 +19,10 @@
> */
> #define SEC(NAME) __attribute__((section(NAME), used))
>
> +#ifndef __always_inline
> +#define __always_inline __attribute__((always_inline))
> +#endif
> +
> /* helper functions called from eBPF programs written in C */
> static void *(*bpf_map_lookup_elem)(void *map, const void *key) =
> (void *) BPF_FUNC_map_lookup_elem;
> @@ -505,7 +509,7 @@ struct pt_regs;
> #endif
>
> /*
> - * BPF_CORE_READ abstracts away bpf_probe_read() call and captures offset
> + * bpf_core_read() abstracts away bpf_probe_read() call and captures field
> * relocation for source address using __builtin_preserve_access_index()
> * built-in, provided by Clang.
> *
> @@ -520,8 +524,147 @@ struct pt_regs;
> * actual field offset, based on target kernel BTF type that matches original
> * (local) BTF, used to record relocation.
> */
> -#define BPF_CORE_READ(dst, src) \
> - bpf_probe_read((dst), sizeof(*(src)), \
> - __builtin_preserve_access_index(src))
> +#define bpf_core_read(dst, sz, src) \
> + bpf_probe_read(dst, sz, \
> + (const void *)__builtin_preserve_access_index(src))
> +
> +/*
> + * bpf_core_read_str() is a thin wrapper around bpf_probe_read_str()
> + * additionally emitting BPF CO-RE field relocation for specified source
> + * argument.
> + */
> +#define bpf_core_read_str(dst, sz, src) \
> + bpf_probe_read_str(dst, sz, \
> + (const void *)__builtin_preserve_access_index(src))
> +
> +#define ___concat(a, b) a ## b
> +#define ___apply(fn, n) ___concat(fn, n)
> +#define ___nth(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, __11, N, ...) N
We are adding many marcos with simple names: ___apply(), ___nth. So I worry
they may conflict with macro definitions from other libraries. Shall we hide
them in .c files or prefix/postfix them with _libbpf or something?
Thanks,
Song
next prev parent reply other threads:[~2019-10-01 21:14 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-30 18:58 [PATCH bpf-next 0/6] Move bpf_helpers and add BPF_CORE_READ macros Andrii Nakryiko
2019-09-30 18:58 ` [PATCH bpf-next 1/6] selftests/bpf: undo GCC-specific bpf_helpers.h changes Andrii Nakryiko
2019-09-30 22:53 ` Song Liu
2019-10-01 10:25 ` Ilya Leoshkevich
2019-10-01 19:10 ` John Fastabend
2019-09-30 18:58 ` [PATCH bpf-next 2/6] libbpf: move bpf_helpers.h, bpf_endian.h into libbpf Andrii Nakryiko
2019-09-30 22:55 ` Song Liu
2019-09-30 22:58 ` Andrii Nakryiko
2019-09-30 23:18 ` Jakub Kicinski
2019-09-30 23:25 ` Song Liu
2019-09-30 23:36 ` Jakub Kicinski
2019-09-30 23:39 ` Song Liu
2019-09-30 23:30 ` Andrii Nakryiko
2019-09-30 23:43 ` Jakub Kicinski
2019-09-30 23:23 ` Song Liu
2019-09-30 23:27 ` Andrii Nakryiko
2019-09-30 23:35 ` Song Liu
2019-10-01 7:10 ` Toke Høiland-Jørgensen
2019-10-01 19:18 ` John Fastabend
2019-10-01 19:44 ` Andrii Nakryiko
2019-10-01 22:00 ` John Fastabend
2019-10-02 7:25 ` Toke Høiland-Jørgensen
2019-10-01 19:42 ` Andrii Nakryiko
2019-10-02 7:21 ` Toke Høiland-Jørgensen
2019-10-01 21:19 ` Song Liu
2019-10-01 21:28 ` Andrii Nakryiko
2019-10-01 22:45 ` Daniel Borkmann
2019-10-01 23:31 ` Andrii Nakryiko
2019-10-01 23:40 ` Andrii Nakryiko
2019-10-02 9:51 ` Daniel Borkmann
2019-09-30 18:58 ` [PATCH bpf-next 3/6] selftests/bpf: switch test to use libbpf's helpers Andrii Nakryiko
2019-09-30 18:58 ` [PATCH bpf-next 4/6] libbpf: add BPF_CORE_READ/BPF_CORE_READ_INTO helpers Andrii Nakryiko
2019-10-01 19:07 ` John Fastabend
2019-10-01 21:14 ` Song Liu [this message]
2019-10-01 21:25 ` Andrii Nakryiko
2019-10-01 21:46 ` Song Liu
2019-10-01 22:42 ` Andrii Nakryiko
2019-10-01 23:44 ` Song Liu
2019-10-02 3:36 ` Andrii Nakryiko
2019-10-02 16:25 ` Song Liu
2019-09-30 18:58 ` [PATCH bpf-next 5/6] selftests/bpf: adjust CO-RE reloc tests for new BPF_CORE_READ macro Andrii Nakryiko
2019-10-01 19:14 ` John Fastabend
2019-10-01 21:31 ` Andrii Nakryiko
2019-10-01 21:47 ` Song Liu
2019-09-30 18:58 ` [PATCH bpf-next 6/6] selftests/bpf: add BPF_CORE_READ and BPF_CORE_READ_STR_INTO macro tests Andrii Nakryiko
2019-10-01 19:19 ` John Fastabend
2019-10-01 21:22 ` Song Liu
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