Do not initialize kern_version for TRACING/EXT programs

The TRACING/EXT programs use attach_btf_id and attach_prog_fd
fields from struct bpf_load_program_attr.

The attach_prog_fd field shares space with kern_version,
so by setting kern_version unconditionally we also set
attach_prog_fd to bogus value and kernel fails the load
because it tries to look it up.

Setting kern_version only for programs other than TRACING/EXT
type.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>

src/cc/bpf_module.cc

@@ -907,7 +907,10 @@ int BPFModule::bcc_func_load(int prog_type, const char *name,
   attr.name = name;
   attr.insns = insns;
   attr.license = license;
-  attr.kern_version = kern_version;
+  if (attr.prog_type != BPF_PROG_TYPE_TRACING &&
+      attr.prog_type != BPF_PROG_TYPE_EXT) {
+    attr.kern_version = kern_version;
+  }
   attr.log_level = log_level;
   if (dev_name)
     attr.prog_ifindex = if_nametoindex(dev_name);

src/cc/libbpf.c

@@ -671,7 +671,8 @@ int bcc_prog_load(enum bpf_prog_type prog_type, const char *name,
   attr.name = name;
   attr.insns = insns;
   attr.license = license;
-  attr.kern_version = kern_version;
+  if (prog_type != BPF_PROG_TYPE_TRACING && prog_type != BPF_PROG_TYPE_EXT)
+    attr.kern_version = kern_version;
   attr.log_level = log_level;
   return bcc_prog_load_xattr(&attr, prog_len, log_buf, log_buf_size, true);
 }