selftests/bpf: Test struct_ops map definition with type suffix

Extend struct_ops_module test case to check if it is possible to use
'___' suffixes for struct_ops type specification.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20240306104529.6453-5-eddyz87@gmail.com

tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c

@@ -564,6 +564,8 @@ static int bpf_dummy_reg(void *kdata)
 {
 	struct bpf_testmod_ops *ops = kdata;
 
+	if (ops->test_1)
+		ops->test_1();
 	/* Some test cases (ex. struct_ops_maybe_null) may not have test_2
 	 * initialized, so we need to check for NULL.
 	 */

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

@@ -30,11 +30,29 @@ static void check_map_info(struct bpf_map_info *info)
 	close(fd);
 }
 
+static int attach_ops_and_check(struct struct_ops_module *skel,
+				struct bpf_map *map,
+				int expected_test_2_result)
+{
+	struct bpf_link *link;
+
+	link = bpf_map__attach_struct_ops(map);
+	ASSERT_OK_PTR(link, "attach_test_mod_1");
+	if (!link)
+		return -1;
+
+	/* test_{1,2}() would be called from bpf_dummy_reg() in bpf_testmod.c */
+	ASSERT_EQ(skel->bss->test_1_result, 0xdeadbeef, "test_1_result");
+	ASSERT_EQ(skel->bss->test_2_result, expected_test_2_result, "test_2_result");
+
+	bpf_link__destroy(link);
+	return 0;
+}
+
 static void test_struct_ops_load(void)
 {
 	struct struct_ops_module *skel;
 	struct bpf_map_info info = {};
-	struct bpf_link *link;
 	int err;
 	u32 len;
 
@@ -59,20 +77,17 @@ static void test_struct_ops_load(void)
 	if (!ASSERT_OK(err, "bpf_map_get_info_by_fd"))
 		goto cleanup;
 
-	link = bpf_map__attach_struct_ops(skel->maps.testmod_1);
-	ASSERT_OK_PTR(link, "attach_test_mod_1");
-
+	check_map_info(&info);
 	/* test_3() will be called from bpf_dummy_reg() in bpf_testmod.c
 	 *
 	 * In bpf_testmod.c it will pass 4 and 13 (the value of data) to
 	 * .test_2.  So, the value of test_2_result should be 20 (4 + 13 +
 	 * 3).
 	 */
-	ASSERT_EQ(skel->bss->test_2_result, 20, "check_shadow_variables");
-
-	bpf_link__destroy(link);
-
-	check_map_info(&info);
+	if (!attach_ops_and_check(skel, skel->maps.testmod_1, 20))
+		goto cleanup;
+	if (!attach_ops_and_check(skel, skel->maps.testmod_2, 12))
+		goto cleanup;
 
 cleanup:
 	struct_ops_module__destroy(skel);

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

@@ -7,12 +7,14 @@
 
 char _license[] SEC("license") = "GPL";
 
+int test_1_result = 0;
 int test_2_result = 0;
 
 SEC("struct_ops/test_1")
 int BPF_PROG(test_1)
 {
-	return 0xdeadbeef;
+	test_1_result = 0xdeadbeef;
+	return 0;
 }
 
 SEC("struct_ops/test_2")
@@ -35,3 +37,20 @@ struct bpf_testmod_ops testmod_1 = {
 	.data = 0x1,
 };
 
+SEC("struct_ops/test_2")
+void BPF_PROG(test_2_v2, int a, int b)
+{
+	test_2_result = a * b;
+}
+
+struct bpf_testmod_ops___v2 {
+	int (*test_1)(void);
+	void (*test_2)(int a, int b);
+	int (*test_maybe_null)(int dummy, struct task_struct *task);
+};
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops___v2 testmod_2 = {
+	.test_1 = (void *)test_1,
+	.test_2 = (void *)test_2_v2,
+};