bpf/selftests: Check errno when percpu map value size exceeds

This test case checks the errno message when percpu map value size
exceeds PCPU_MIN_UNIT_SIZE.

root@debian:~# ./test_progs -t map_init
 torvalds#160/1   map_init/pcpu_map_init:OK
 torvalds#160/2   map_init/pcpu_lru_map_init:OK
 torvalds#160/3   map_init/pcpu map value size:OK
 torvalds#160     map_init:OK
Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Tao Chen <chen.dylane@gmail.com>
Signed-off-by: jinke han <jinkehan@didiglobal.com>

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

@@ -6,6 +6,7 @@
 
 #define TEST_VALUE 0x1234
 #define FILL_VALUE 0xdeadbeef
+#define PCPU_MIN_UNIT_SIZE 32768
 
 static int nr_cpus;
 static int duration;
@@ -118,6 +119,35 @@ static int check_values_one_cpu(pcpu_map_value_t *value, map_value_t expected)
 
 	return 0;
 }
+/*
+ * percpu map value size is bound by PCPU_MIN_UNIT_SIZE
+ * check the errno when the value exceed PCPU_MIN_UNIT_SIZE
+ */
+static void test_pcpu_map_value_size(void)
+{
+	struct test_map_init *skel;
+	int err;
+	int value_sz = PCPU_MIN_UNIT_SIZE + 1;
+	enum bpf_map_type map_types[] = { BPF_MAP_TYPE_PERCPU_ARRAY,
+					  BPF_MAP_TYPE_PERCPU_HASH,
+					  BPF_MAP_TYPE_LRU_PERCPU_HASH };
+	for (int i = 0; i < ARRAY_SIZE(map_types); i++) {
+		skel = test_map_init__open();
+		if (!ASSERT_OK_PTR(skel, "skel_open"))
+			return;
+		err = bpf_map__set_type(skel->maps.hashmap2, map_types[i]);
+		if (!ASSERT_OK(err, "bpf_map__set_type"))
+			goto error;
+		err = bpf_map__set_value_size(skel->maps.hashmap2, value_sz);
+		if (!ASSERT_OK(err, "bpf_map__set_value_size"))
+			goto error;
+
+		err = test_map_init__load(skel);
+		ASSERT_EQ(err, -E2BIG, "skel_load");
+error:
+		test_map_init__destroy(skel);
+	}
+}
 
 /* Add key=1 elem with values set for all CPUs
  * Delete elem key=1
@@ -211,4 +241,6 @@ void test_map_init(void)
 		test_pcpu_map_init();
 	if (test__start_subtest("pcpu_lru_map_init"))
 		test_pcpu_lru_map_init();
+	if (test__start_subtest("pcpu map value size"))
+		test_pcpu_map_value_size();
 }

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

@@ -15,6 +15,12 @@ struct {
 	__type(value, __u64);
 } hashmap1 SEC(".maps");
 
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} hashmap2 SEC(".maps");
 
 SEC("tp/syscalls/sys_enter_getpgid")
 int sysenter_getpgid(const void *ctx)