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

Tao Chen
2025-01-24T14:44:47Z

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(),
};
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