Add tests to verify that the kernel reports the expected error messages
when map creation fails.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
.../selftests/bpf/prog_tests/map_init.c | 168 ++++++++++++++++++
1 file changed, 168 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/map_init.c b/tools/testing/selftests/bpf/prog_tests/map_init.c
index 14a31109dd0e..89e6daf2fcfd 100644
--- a/tools/testing/selftests/bpf/prog_tests/map_init.c
+++ b/tools/testing/selftests/bpf/prog_tests/map_init.c
@@ -212,3 +212,171 @@ void test_map_init(void)
if (test__start_subtest("pcpu_lru_map_init"))
test_pcpu_lru_map_init();
}
+
+#define BPF_LOG_FIXED 8
+
+static void test_map_create(enum bpf_map_type map_type, const char *map_name,
+ struct bpf_map_create_opts *opts, const char *exp_msg)
+{
+ const int key_size = 4, value_size = 4, max_entries = 1;
+ char log_buf[128];
+ int fd;
+ LIBBPF_OPTS(bpf_log_opts, log_opts);
+
+ log_buf[0] = '\0';
+ log_opts.log_buf = log_buf;
+ log_opts.log_size = sizeof(log_buf);
+ log_opts.log_level = BPF_LOG_FIXED;
+ opts->log_opts = &log_opts;
+ fd = bpf_map_create(map_type, map_name, key_size, value_size, max_entries, opts);
+ if (!ASSERT_LT(fd, 0, "bpf_map_create")) {
+ close(fd);
+ return;
+ }
+
+ ASSERT_STREQ(log_buf, exp_msg, "log_buf");
+ ASSERT_EQ(log_opts.log_true_size, strlen(exp_msg) + 1, "log_true_size");
+}
+
+static void test_map_create_array(struct bpf_map_create_opts *opts, const char *exp_msg)
+{
+ test_map_create(BPF_MAP_TYPE_ARRAY, "test_map_create", opts, exp_msg);
+}
+
+static void test_invalid_vmlinux_value_type_id_struct_ops(void)
+{
+ const char *msg = "btf_vmlinux_value_type_id can only be used with struct_ops maps.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .btf_vmlinux_value_type_id = 1,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_invalid_vmlinux_value_type_id_kv_type_id(void)
+{
+ const char *msg = "btf_vmlinux_value_type_id is mutually exclusive with btf_key_type_id and btf_value_type_id.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .btf_vmlinux_value_type_id = 1,
+ .btf_key_type_id = 1,
+ );
+
+ test_map_create(BPF_MAP_TYPE_STRUCT_OPS, "test_map_create", &opts, msg);
+}
+
+static void test_invalid_value_type_id(void)
+{
+ const char *msg = "Invalid btf_value_type_id.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .btf_key_type_id = 1,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_invalid_map_extra(void)
+{
+ const char *msg = "Invalid map_extra.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .map_extra = 1,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_invalid_numa_node(void)
+{
+ const char *msg = "Invalid numa_node.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .map_flags = BPF_F_NUMA_NODE,
+ .numa_node = 0xFF,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_invalid_map_type(void)
+{
+ const char *msg = "Invalid map_type.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts);
+
+ test_map_create(__MAX_BPF_MAP_TYPE, "test_map_create", &opts, msg);
+}
+
+static void test_invalid_token_fd(void)
+{
+ const char *msg = "Invalid map_token_fd.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .map_flags = BPF_F_TOKEN_FD,
+ .token_fd = 0xFF,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_invalid_map_name(void)
+{
+ const char *msg = "Invalid map_name.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts);
+
+ test_map_create(BPF_MAP_TYPE_ARRAY, "test-!@#", &opts, msg);
+}
+
+static void test_invalid_btf_fd(void)
+{
+ const char *msg = "Invalid btf_fd.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .btf_fd = -1,
+ .btf_key_type_id = 1,
+ .btf_value_type_id = 1,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_excl_prog_hash_size_1(void)
+{
+ const char *msg = "Invalid excl_prog_hash_size.\n";
+ const char *hash = "DEADCODE";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .excl_prog_hash = hash,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+static void test_excl_prog_hash_size_2(void)
+{
+ const char *msg = "Invalid excl_prog_hash_size.\n";
+ LIBBPF_OPTS(bpf_map_create_opts, opts,
+ .excl_prog_hash_size = 1,
+ );
+
+ test_map_create_array(&opts, msg);
+}
+
+void test_map_create_failure(void)
+{
+ if (test__start_subtest("invalid_vmlinux_value_type_id_struct_ops"))
+ test_invalid_vmlinux_value_type_id_struct_ops();
+ if (test__start_subtest("invalid_vmlinux_value_type_id_kv_type_id"))
+ test_invalid_vmlinux_value_type_id_kv_type_id();
+ if (test__start_subtest("invalid_value_type_id"))
+ test_invalid_value_type_id();
+ if (test__start_subtest("invalid_map_extra"))
+ test_invalid_map_extra();
+ if (test__start_subtest("invalid_numa_node"))
+ test_invalid_numa_node();
+ if (test__start_subtest("invalid_map_type"))
+ test_invalid_map_type();
+ if (test__start_subtest("invalid_token_fd"))
+ test_invalid_token_fd();
+ if (test__start_subtest("invalid_map_name"))
+ test_invalid_map_name();
+ if (test__start_subtest("invalid_btf_fd"))
+ test_invalid_btf_fd();
+ if (test__start_subtest("invalid_excl_prog_hash_size_1"))
+ test_excl_prog_hash_size_1();
+ if (test__start_subtest("invalid_excl_prog_hash_size_2"))
+ test_excl_prog_hash_size_2();
+}
--
2.52.0On Mon, Feb 2, 2026 at 6:43 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>
> +
> +#define BPF_LOG_FIXED 8
> +
> +static void test_map_create(enum bpf_map_type map_type, const char *map_name,
> + struct bpf_map_create_opts *opts, const char *exp_msg)
> +{
> + const int key_size = 4, value_size = 4, max_entries = 1;
> + char log_buf[128];
> + int fd;
> + LIBBPF_OPTS(bpf_log_opts, log_opts);
> +
> + log_buf[0] = '\0';
> + log_opts.log_buf = log_buf;
> + log_opts.log_size = sizeof(log_buf);
> + log_opts.log_level = BPF_LOG_FIXED;
Why? Which part of the test needs the log with this flag?
On 5/2/26 04:14, Alexei Starovoitov wrote:
> On Mon, Feb 2, 2026 at 6:43 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>> +
>> +#define BPF_LOG_FIXED 8
>> +
>> +static void test_map_create(enum bpf_map_type map_type, const char *map_name,
>> + struct bpf_map_create_opts *opts, const char *exp_msg)
>> +{
>> + const int key_size = 4, value_size = 4, max_entries = 1;
>> + char log_buf[128];
>> + int fd;
>> + LIBBPF_OPTS(bpf_log_opts, log_opts);
>> +
>> + log_buf[0] = '\0';
>> + log_opts.log_buf = log_buf;
>> + log_opts.log_size = sizeof(log_buf);
>> + log_opts.log_level = BPF_LOG_FIXED;
>
> Why? Which part of the test needs the log with this flag?
BPF_LOG_FIXED looks odd here.
This test sets 'log_level = BPF_LOG_FIXED' to match the behavior of
bpf_vlog_init() as initialized by bpf_log_attr_create_vlog() in
patch #7. BPF_LOG_FIXED is intended to be the default log_level
there.
Thanks,
Leon
On Wed, Feb 4, 2026 at 7:54 PM Leon Hwang <leon.hwang@linux.dev> wrote:
>
>
>
> On 5/2/26 04:14, Alexei Starovoitov wrote:
> > On Mon, Feb 2, 2026 at 6:43 AM Leon Hwang <leon.hwang@linux.dev> wrote:
> >>
> >> +
> >> +#define BPF_LOG_FIXED 8
> >> +
> >> +static void test_map_create(enum bpf_map_type map_type, const char *map_name,
> >> + struct bpf_map_create_opts *opts, const char *exp_msg)
> >> +{
> >> + const int key_size = 4, value_size = 4, max_entries = 1;
> >> + char log_buf[128];
> >> + int fd;
> >> + LIBBPF_OPTS(bpf_log_opts, log_opts);
> >> +
> >> + log_buf[0] = '\0';
> >> + log_opts.log_buf = log_buf;
> >> + log_opts.log_size = sizeof(log_buf);
> >> + log_opts.log_level = BPF_LOG_FIXED;
> >
> > Why? Which part of the test needs the log with this flag?
>
> BPF_LOG_FIXED looks odd here.
>
> This test sets 'log_level = BPF_LOG_FIXED' to match the behavior of
> bpf_vlog_init() as initialized by bpf_log_attr_create_vlog() in
> patch #7. BPF_LOG_FIXED is intended to be the default log_level
> there.
I don't think you answered my question.
bpf_vlog_init() is using whatever log_level user space provided.
Why do you pass BPF_LOG_FIXED ?
On 6/2/26 07:18, Alexei Starovoitov wrote:
> On Wed, Feb 4, 2026 at 7:54 PM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>>
>>
>> On 5/2/26 04:14, Alexei Starovoitov wrote:
>>> On Mon, Feb 2, 2026 at 6:43 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>>>
>>>> +
>>>> +#define BPF_LOG_FIXED 8
>>>> +
>>>> +static void test_map_create(enum bpf_map_type map_type, const char *map_name,
>>>> + struct bpf_map_create_opts *opts, const char *exp_msg)
>>>> +{
>>>> + const int key_size = 4, value_size = 4, max_entries = 1;
>>>> + char log_buf[128];
>>>> + int fd;
>>>> + LIBBPF_OPTS(bpf_log_opts, log_opts);
>>>> +
>>>> + log_buf[0] = '\0';
>>>> + log_opts.log_buf = log_buf;
>>>> + log_opts.log_size = sizeof(log_buf);
>>>> + log_opts.log_level = BPF_LOG_FIXED;
>>>
>>> Why? Which part of the test needs the log with this flag?
>>
>> BPF_LOG_FIXED looks odd here.
>>
>> This test sets 'log_level = BPF_LOG_FIXED' to match the behavior of
>> bpf_vlog_init() as initialized by bpf_log_attr_create_vlog() in
>> patch #7. BPF_LOG_FIXED is intended to be the default log_level
>> there.
>
> I don't think you answered my question.
> bpf_vlog_init() is using whatever log_level user space provided.
> Why do you pass BPF_LOG_FIXED ?
>
The intention behind passing BPF_LOG_FIXED was to ensure the log used
the buffer in a fixed mode, since the allocated buffer was large enough
to hold the full log message from the kernel. It was not intended to
test against log_level itself.
After reviewing commit 121664093803 ("bpf: Switch BPF verifier log to be
a rotating log by default"), I realized that BPF_LOG_FIXED was
introduced specifically to disable the rotating log behavior. In this
test case, that distinction is not relevant, so BPF_LOG_FIXED is indeed
unnecessary.
I tested with 'log_level is 0' and 'log_level is non-zero'. The tests
fail when log_level is 0, and pass when log_level is non-zero. So I will
switch to using 'log_level = 1' in the next revision.
Thanks,
Leon
© 2016 - 2026 Red Hat, Inc.