From: Jakub Sitnicki <jakub@cloudflare.com>
To: Eelco Chaudron <echaudro@redhat.com>
Cc: bpf@vger.kernel.org, davem@davemloft.net, netdev@vger.kernel.org,
ast@kernel.org, daniel@iogearbox.net, kafai@fb.com,
songliubraving@fb.com, yhs@fb.com, andriin@fb.com,
toke@redhat.com
Subject: Re: [PATCH bpf-next v4 2/3] libbpf: Add support for dynamic program attach target
Date: Tue, 18 Feb 2020 16:34:08 +0000 [thread overview]
Message-ID: <877e0jam7z.fsf@cloudflare.com> (raw)
In-Reply-To: <158194341424.104074.4927911845622583345.stgit@xdp-tutorial>
Hey Eelco,
On Mon, Feb 17, 2020 at 12:43 PM GMT, Eelco Chaudron wrote:
> Currently when you want to attach a trace program to a bpf program
> the section name needs to match the tracepoint/function semantics.
>
> However the addition of the bpf_program__set_attach_target() API
> allows you to specify the tracepoint/function dynamically.
>
> The call flow would look something like this:
>
> xdp_fd = bpf_prog_get_fd_by_id(id);
> trace_obj = bpf_object__open_file("func.o", NULL);
> prog = bpf_object__find_program_by_title(trace_obj,
> "fentry/myfunc");
> bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY);
> bpf_program__set_attach_target(prog, xdp_fd,
> "xdpfilt_blk_all");
> bpf_object__load(trace_obj)
>
> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
> ---
> tools/lib/bpf/libbpf.c | 34 ++++++++++++++++++++++++++++++----
> tools/lib/bpf/libbpf.h | 4 ++++
> tools/lib/bpf/libbpf.map | 2 ++
> 3 files changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 514b1a524abb..0c25d78fb5d8 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
[...]
> @@ -8132,6 +8133,31 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
> }
> }
>
> +int bpf_program__set_attach_target(struct bpf_program *prog,
> + int attach_prog_fd,
> + const char *attach_func_name)
> +{
> + int btf_id;
> +
> + if (!prog || attach_prog_fd < 0 || !attach_func_name)
> + return -EINVAL;
> +
> + if (attach_prog_fd)
> + btf_id = libbpf_find_prog_btf_id(attach_func_name,
> + attach_prog_fd);
> + else
> + btf_id = __find_vmlinux_btf_id(prog->obj->btf_vmlinux,
> + attach_func_name,
> + prog->expected_attach_type);
> +
> + if (btf_id <= 0)
> + return btf_id;
Looks like we can get 0 as return value on both error and success
(below)? Is that intentional?
> +
> + prog->attach_btf_id = btf_id;
> + prog->attach_prog_fd = attach_prog_fd;
> + return 0;
> +}
> +
> int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
> {
> int err = 0, n, len, start, end = -1;
[...]
next prev parent reply other threads:[~2020-02-18 16:34 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-17 12:42 [PATCH bpf-next v4 0/3] libbpf: Add support for dynamic program attach target Eelco Chaudron
2020-02-17 12:43 ` [PATCH bpf-next v4 1/3] libbpf: Bump libpf current version to v0.0.8 Eelco Chaudron
2020-02-17 12:43 ` [PATCH bpf-next v4 2/3] libbpf: Add support for dynamic program attach target Eelco Chaudron
2020-02-18 16:34 ` Jakub Sitnicki [this message]
2020-02-18 21:24 ` Andrii Nakryiko
2020-02-19 11:06 ` Eelco Chaudron
2020-02-19 17:41 ` Andrii Nakryiko
2020-02-20 13:21 ` Eelco Chaudron
2020-02-17 12:43 ` [PATCH bpf-next v4 3/3] selftests/bpf: update xdp_bpf2bpf test to use new set_attach_target API Eelco Chaudron
2020-02-18 21:21 ` Andrii Nakryiko
2020-02-19 10:54 ` Eelco Chaudron
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