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Mon, 7 Jun 2021 18:28:51 +0000 (UTC) Received: from krava (unknown [10.40.192.167]) by smtp.corp.redhat.com (Postfix) with SMTP id DD4325D736; Mon, 7 Jun 2021 18:28:48 +0000 (UTC) Date: Mon, 7 Jun 2021 20:28:48 +0200 From: Jiri Olsa To: Yonghong Song Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "Steven Rostedt (VMware)" , netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , John Fastabend , KP Singh , Daniel Xu , Viktor Malik Subject: Re: [PATCH 15/19] libbpf: Add support to link multi func tracing program Message-ID: References: <20210605111034.1810858-1-jolsa@kernel.org> <20210605111034.1810858-16-jolsa@kernel.org> <50f92d1e-1138-656c-4318-8fecf61f2025@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50f92d1e-1138-656c-4318-8fecf61f2025@fb.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Jun 06, 2021 at 10:49:16PM -0700, Yonghong Song wrote: > > > On 6/5/21 4:10 AM, Jiri Olsa wrote: > > Adding support to link multi func tracing program > > through link_create interface. > > > > Adding special types for multi func programs: > > > > fentry.multi > > fexit.multi > > > > so you can define multi func programs like: > > > > SEC("fentry.multi/bpf_fentry_test*") > > int BPF_PROG(test1, unsigned long ip, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f) > > > > that defines test1 to be attached to bpf_fentry_test* functions, > > and able to attach ip and 6 arguments. > > > > If functions are not specified the program needs to be attached > > manually. > > > > Adding new btf id related fields to bpf_link_create_opts and > > bpf_link_create to use them. > > > > Signed-off-by: Jiri Olsa > > --- > > tools/lib/bpf/bpf.c | 11 ++++++- > > tools/lib/bpf/bpf.h | 4 ++- > > tools/lib/bpf/libbpf.c | 72 ++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 85 insertions(+), 2 deletions(-) > > > > diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c > > index 86dcac44f32f..da892737b522 100644 > > --- a/tools/lib/bpf/bpf.c > > +++ b/tools/lib/bpf/bpf.c > > @@ -674,7 +674,8 @@ int bpf_link_create(int prog_fd, int target_fd, > > enum bpf_attach_type attach_type, > > const struct bpf_link_create_opts *opts) > > { > > - __u32 target_btf_id, iter_info_len; > > + __u32 target_btf_id, iter_info_len, multi_btf_ids_cnt; > > + __s32 *multi_btf_ids; > > union bpf_attr attr; > > int fd; > [...] > > @@ -9584,6 +9597,9 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, > > if (!name) > > return -EINVAL; > > + if (prog->prog_flags & BPF_F_MULTI_FUNC) > > + return 0; > > + > > for (i = 0; i < ARRAY_SIZE(section_defs); i++) { > > if (!section_defs[i].is_attach_btf) > > continue; > > @@ -10537,6 +10553,62 @@ static struct bpf_link *bpf_program__attach_btf_id(struct bpf_program *prog) > > return (struct bpf_link *)link; > > } > > +static struct bpf_link *bpf_program__attach_multi(struct bpf_program *prog) > > +{ > > + char *pattern = prog->sec_name + prog->sec_def->len; > > + DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts); > > + enum bpf_attach_type attach_type; > > + int prog_fd, link_fd, cnt, err; > > + struct bpf_link *link = NULL; > > + __s32 *ids = NULL; > > + > > + prog_fd = bpf_program__fd(prog); > > + if (prog_fd < 0) { > > + pr_warn("prog '%s': can't attach before loaded\n", prog->name); > > + return ERR_PTR(-EINVAL); > > + } > > + > > + err = bpf_object__load_vmlinux_btf(prog->obj, true); > > + if (err) > > + return ERR_PTR(err); > > + > > + cnt = btf__find_by_pattern_kind(prog->obj->btf_vmlinux, pattern, > > + BTF_KIND_FUNC, &ids); > > + if (cnt <= 0) > > + return ERR_PTR(-EINVAL); > > In kernel, looks like we support cnt = 0, here we error out. > Should we also error out in the kernel if cnt == 0? hum, I'm not what you mean.. what kernel code are you referring to? thanks, jirka