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Sat, 25 Jan 2025 07:05:28 -0800 (PST) Message-ID: Date: Sat, 25 Jan 2025 23:05:23 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next v3 1/3] libbpf: Refactor libbpf_probe_bpf_helper To: Andrii Nakryiko Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, haoluo@google.com, jolsa@kernel.org, qmo@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250124144411.13468-1-chen.dylane@gmail.com> <20250124144411.13468-2-chen.dylane@gmail.com> From: Tao Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2025/1/25 02:44, Andrii Nakryiko 写道: > On Fri, Jan 24, 2025 at 6:44 AM Tao Chen wrote: >> >> Extract the common part as probe_func_comm, which will be used in >> both libbpf_probe_bpf_{helper, kfunc} >> >> Signed-off-by: Tao Chen >> --- >> tools/lib/bpf/libbpf_probes.c | 38 ++++++++++++++++++++++++----------- >> 1 file changed, 26 insertions(+), 12 deletions(-) >> >> diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c >> index 9dfbe7750f56..b73345977b4e 100644 >> --- a/tools/lib/bpf/libbpf_probes.c >> +++ b/tools/lib/bpf/libbpf_probes.c >> @@ -413,22 +413,20 @@ int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts) >> return libbpf_err(ret); >> } >> >> -int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, >> - const void *opts) >> +static int probe_func_comm(enum bpf_prog_type prog_type, struct bpf_insn insn, >> + char *accepted_msgs, size_t msgs_size) >> { >> struct bpf_insn insns[] = { >> - BPF_EMIT_CALL((__u32)helper_id), >> + BPF_EXIT_INSN(), >> BPF_EXIT_INSN(), >> }; >> const size_t insn_cnt = ARRAY_SIZE(insns); >> - char buf[4096]; >> - int ret; >> + int err; >> >> - if (opts) >> - return libbpf_err(-EINVAL); >> + insns[0] = insn; >> >> /* we can't successfully load all prog types to check for BPF helper >> - * support, so bail out with -EOPNOTSUPP error >> + * and kfunc support, so bail out with -EOPNOTSUPP error >> */ >> switch (prog_type) { >> case BPF_PROG_TYPE_TRACING: > > there isn't much logic that you will extract here besides this check > whether program type can even be successfully loaded, so I wouldn't > extract probe_func_comm(), but rather extract just the check: > > static bool can_probe_prog_type(enum bpf_prog_type prog_type) > { > /* we can't successfully load all prog types to check for BPF > helper/kfunc > * support, so check this early and bail > */ > switch (prog_type) { > ...: return false > default: > return true; > } > > > And just check that can_probe_prog_type() inside > libbpf_probe_bpf_helper and libbpf_probe_bpf_kfunc > > pw-bot: cr > Hi Andrii, Thank you for your review, jiri also suggested putting the insn part back into libbpf_bpf_probe_{helper, kfunc}, so I'll make the modifications as you suggested in v4. >> @@ -440,10 +438,26 @@ int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helpe >> break; >> } >> >> - buf[0] = '\0'; >> - ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf)); >> - if (ret < 0) >> - return libbpf_err(ret); >> + accepted_msgs[0] = '\0'; >> + err = probe_prog_load(prog_type, insns, insn_cnt, accepted_msgs, msgs_size); >> + if (err < 0) >> + return libbpf_err(err); >> + >> + return 0; >> +} >> + >> +int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, >> + const void *opts) >> +{ >> + char buf[4096]; >> + int ret; >> + >> + if (opts) >> + return libbpf_err(-EINVAL); >> + >> + ret = probe_func_comm(prog_type, BPF_EMIT_CALL((__u32)helper_id), buf, sizeof(buf)); >> + if (ret) >> + return ret; >> >> /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id) >> * at all, it will emit something like "invalid func unknown#181". >> -- >> 2.43.0 >> -- Best Regards Dylane Chen