For raw tracepoint program types libbpf will try to find
btf_id of raw tracepoint in vmlinux's BTF.
It's a responsiblity of bpf program author to annotate the program
with SEC("raw_tracepoint/name") where "name" is a valid raw tracepoint.
If "name" is indeed a valid raw tracepoint then in-kernel BTF
will have "btf_trace_##name" typedef that points to function
prototype of that raw tracepoint. BTF description captures
exact argument the kernel C code is passing into raw tracepoint.
The kernel verifier will check the types while loading bpf program.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e0276520171b..0e6f7b41c521 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4591,6 +4591,22 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
continue;
*prog_type = section_names[i].prog_type;
*expected_attach_type = section_names[i].expected_attach_type;
+ if (*prog_type == BPF_PROG_TYPE_RAW_TRACEPOINT) {
+ struct btf *btf = bpf_core_find_kernel_btf();
+ char raw_tp_btf_name[128] = "btf_trace_";
+ int ret;
+
+ if (IS_ERR(btf))
+ /* lack of kernel BTF is not a failure */
+ return 0;
+ /* append "btf_trace_" prefix per kernel convention */
+ strcpy(raw_tp_btf_name + sizeof("btf_trace_") - 1,
+ name + section_names[i].len);
+ ret = btf__find_by_name(btf, raw_tp_btf_name);
+ if (ret > 0)
+ *expected_attach_type = ret;
+ btf__free(btf);
+ }
return 0;
}
pr_warning("failed to guess program type based on ELF section name '%s'\n", name);
--
2.20.0
