bpf: selftests: Add test for different inner map size

This patch tests the inner map size can be different
for reuseport_sockarray but has to be the same for
arraymap.  A new subtest "diff_size" is added for this.

The existing test is moved to a subtest "lookup_update".
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200828011819.1970825-1-kafai@fb.com

tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c

@@ -53,7 +53,7 @@ static int kern_sync_rcu(void)
 	return err;
 }
 
-void test_btf_map_in_map(void)
+static void test_lookup_update(void)
 {
 	int err, key = 0, val, i;
 	struct test_btf_map_in_map *skel;
@@ -143,3 +143,36 @@ void test_btf_map_in_map(void)
 cleanup:
 	test_btf_map_in_map__destroy(skel);
 }
+
+static void test_diff_size(void)
+{
+	struct test_btf_map_in_map *skel;
+	int err, inner_map_fd, zero = 0;
+
+	skel = test_btf_map_in_map__open_and_load();
+	if (CHECK(!skel, "skel_open", "failed to open&load skeleton\n"))
+		return;
+
+	inner_map_fd = bpf_map__fd(skel->maps.sockarr_sz2);
+	err = bpf_map_update_elem(bpf_map__fd(skel->maps.outer_sockarr), &zero,
+				  &inner_map_fd, 0);
+	CHECK(err, "outer_sockarr inner map size check",
+	      "cannot use a different size inner_map\n");
+
+	inner_map_fd = bpf_map__fd(skel->maps.inner_map_sz2);
+	err = bpf_map_update_elem(bpf_map__fd(skel->maps.outer_arr), &zero,
+				  &inner_map_fd, 0);
+	CHECK(!err, "outer_arr inner map size check",
+	      "incorrectly updated with a different size inner_map\n");
+
+	test_btf_map_in_map__destroy(skel);
+}
+
+void test_btf_map_in_map(void)
+{
+	if (test__start_subtest("lookup_update"))
+		test_lookup_update();
+
+	if (test__start_subtest("diff_size"))
+		test_diff_size();
+}

tools/testing/selftests/bpf/progs/test_btf_map_in_map.c

@@ -11,6 +11,13 @@ struct inner_map {
 } inner_map1 SEC(".maps"),
   inner_map2 SEC(".maps");
 
+struct inner_map_sz2 {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 2);
+	__type(key, int);
+	__type(value, int);
+} inner_map_sz2 SEC(".maps");
+
 struct outer_arr {
 	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
 	__uint(max_entries, 3);
@@ -50,6 +57,30 @@ struct outer_hash {
 	},
 };
 
+struct sockarr_sz1 {
+	__uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
+	__uint(max_entries, 1);
+	__type(key, int);
+	__type(value, int);
+} sockarr_sz1 SEC(".maps");
+
+struct sockarr_sz2 {
+	__uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
+	__uint(max_entries, 2);
+	__type(key, int);
+	__type(value, int);
+} sockarr_sz2 SEC(".maps");
+
+struct outer_sockarr_sz1 {
+	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
+	__uint(max_entries, 1);
+	__uint(key_size, sizeof(int));
+	__uint(value_size, sizeof(int));
+	__array(values, struct sockarr_sz1);
+} outer_sockarr SEC(".maps") = {
+	.values = { (void *)&sockarr_sz1 },
+};
+
 int input = 0;
 
 SEC("raw_tp/sys_enter")