tools resolve_btfids: Add support for set symbols

The set symbol does not have the unique number suffix,
so we need to give it a special parsing function.

This was omitted in the first batch, because there was
no set support yet, so it slipped in the testing.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-3-jolsa@kernel.org

tools/bpf/resolve_btfids/main.c

@@ -227,6 +227,24 @@ static char *get_id(const char *prefix_end)
 	return id;
 }
 
+static struct btf_id *add_set(struct object *obj, char *name)
+{
+	/*
+	 * __BTF_ID__set__name
+	 * name =    ^
+	 * id   =         ^
+	 */
+	char *id = name + sizeof(BTF_SET "__") - 1;
+	int len = strlen(name);
+
+	if (id >= name + len) {
+		pr_err("FAILED to parse set name: %s\n", name);
+		return NULL;
+	}
+
+	return btf_id__add(&obj->sets, id, true);
+}
+
 static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
 {
 	char *id;
@@ -383,7 +401,7 @@ static int symbols_collect(struct object *obj)
 			id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
 		/* set */
 		} else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
-			id = add_symbol(&obj->sets, prefix, sizeof(BTF_SET) - 1);
+			id = add_set(obj, prefix);
 			/*
 			 * SET objects store list's count, which is encoded
 			 * in symbol's size, together with 'cnt' field hence