Re: [PATCH bpf-next v3 1/3] libbpf: Refactor libbpf_probe_bpf_helper

Tao Chen
2025-01-25T14:52:11Z

在 2025/1/25 00:26, Jiri Olsa 写道:
> On Fri, Jan 24, 2025 at 10:44:09PM +0800, 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 <chen.dylane@gmail.com>
>> ---
>> 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(),
>
> I'd just keep above in libbpf_probe_bpf_helper and pass insns to probe_func_comm,
> seems easier
>
> jirka
>

Hi jiri,
Thank you for your review, your suggestion seems better, i will
send it in v4.

>> };
>> 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:
>> @@ -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