bpftool: Print function linkage in BTF dump

Add printing out BTF_KIND_FUNC's linkage.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200124054317.2459436-1-andriin@fb.com

diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 4ba90d8..b3745ed 100644 (file)
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -77,6 +77,20 @@ static const char *btf_var_linkage_str(__u32 linkage)
        }
 }
 
+static const char *btf_func_linkage_str(const struct btf_type *t)
+{
+       switch (btf_vlen(t)) {
+       case BTF_FUNC_STATIC:
+               return "static";
+       case BTF_FUNC_GLOBAL:
+               return "global";
+       case BTF_FUNC_EXTERN:
+               return "extern";
+       default:
+               return "(unknown)";
+       }
+}
+
 static const char *btf_str(const struct btf *btf, __u32 off)
 {
        if (!off)
@@ -231,12 +245,17 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
                        printf(" fwd_kind=%s", fwd_kind);
                break;
        }
-       case BTF_KIND_FUNC:
-               if (json_output)
+       case BTF_KIND_FUNC: {
+               const char *linkage = btf_func_linkage_str(t);
+
+               if (json_output) {
                        jsonw_uint_field(w, "type_id", t->type);
-               else
-                       printf(" type_id=%u", t->type);
+                       jsonw_string_field(w, "linkage", linkage);
+               } else {
+                       printf(" type_id=%u linkage=%s", t->type, linkage);
+               }
                break;
+       }
        case BTF_KIND_FUNC_PROTO: {
                const struct btf_param *p = (const void *)(t + 1);
                __u16 vlen = BTF_INFO_VLEN(t->info);