From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Hou Tao <houtao1@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH bpf-next v4 2/3] libbpf: support detecting and attaching of writable tracepoint program
Date: Fri, 1 Oct 2021 15:21:04 -0700 [thread overview]
Message-ID: <CAEf4Bzaf5qQOV7jA_U0+E3LhB0X57yJVL0ATqdr-Hui3Rz--=g@mail.gmail.com> (raw)
In-Reply-To: <20210930091355.2794601-3-houtao1@huawei.com>
On Thu, Sep 30, 2021 at 2:00 AM Hou Tao <houtao1@huawei.com> wrote:
>
> Program on writable tracepoint is BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
> but its attachment is the same as BPF_PROG_TYPE_RAW_TRACEPOINT.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
> tools/lib/bpf/libbpf.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 7544d7d09160..80faa53dff35 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -8005,6 +8005,8 @@ static const struct bpf_sec_def section_defs[] = {
> SEC_DEF("tp/", TRACEPOINT, 0, SEC_NONE, attach_tp),
> SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
> SEC_DEF("raw_tp/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
> + SEC_DEF("raw_tracepoint.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
> + SEC_DEF("raw_tp.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
> SEC_DEF("tp_btf/", TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
> SEC_DEF("fentry/", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
> SEC_DEF("fmod_ret/", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
> @@ -9762,12 +9764,21 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr
>
> static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie)
> {
> - const char *tp_name;
> + static const char *prefixes[] = {
> + "raw_tp/",
> + "raw_tracepoint/",
> + "raw_tp.w/",
> + "raw_tracepoint.w/",
> + };
> + size_t i;
> + const char *tp_name = NULL;
>
> - if (str_has_pfx(prog->sec_name, "raw_tp/"))
> - tp_name = prog->sec_name + sizeof("raw_tp/") - 1;
> - else
> - tp_name = prog->sec_name + sizeof("raw_tracepoint/") - 1;
> + for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
> + if (str_has_pfx(prog->sec_name, prefixes[i])) {
> + tp_name = prog->sec_name + strlen(prefixes[i]);
> + break;
> + }
> + }
Let's add if (!tp_name) check here for the future if we forget to
update this prefixes list. It's going to be a really unpleasant
SIGSEGV otherwise.
>
> return bpf_program__attach_raw_tracepoint(prog, tp_name);
> }
> --
> 2.29.2
>
next prev parent reply other threads:[~2021-10-01 22:21 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 9:13 [PATCH bpf-next v4 0/3] add support for writable bare tracepoint Hou Tao
2021-09-30 9:13 ` [PATCH bpf-next v4 1/3] bpf: support writable context for " Hou Tao
2021-10-01 22:21 ` Andrii Nakryiko
2021-09-30 9:13 ` [PATCH bpf-next v4 2/3] libbpf: support detecting and attaching of writable tracepoint program Hou Tao
2021-10-01 22:21 ` Andrii Nakryiko [this message]
2021-09-30 9:13 ` [PATCH bpf-next v4 3/3] bpf/selftests: add test for writable bare tracepoint Hou Tao
2021-09-30 9:13 ` [PATCH bpf-next v4 0/3] add support " Hou Tao
2021-09-30 10:06 ` Hou Tao
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