Hi,
On 3/6/2025 5:12 AM, Emil Tsalapatis wrote:
> Add selftests for the bpf_cpumask_fill helper that sets a bpf_cpumask to
> a bit pattern provided by a BPF program.
>
> Signed-off-by: Emil Tsalapatis (Meta) <emil@xxxxxxxxxxxxxxx>
> ---
> .../selftests/bpf/progs/cpumask_failure.c | 38 ++++++
> .../selftests/bpf/progs/cpumask_success.c | 114 ++++++++++++++++++
> 2 files changed, 152 insertions(+)
My local build failed due to the missed declaration of
"bpf_cpumask_populate" in cpumask_common.h. It reported the following error:
progs/cpumask_success.c:788:8: error: call to undeclared function
'bpf_cpumask_populate'; ISO C99 and later do not support implicit fun
ction declarations [-Wimplicit-function-declaration]
788 | ret = bpf_cpumask_populate((struct cpumask *)local,
&toofewbits, sizeof(toofewbits));
Don't know the reason why CI succeeded.
> diff --git a/tools/testing/selftests/bpf/progs/cpumask_failure.c b/tools/testing/selftests/bpf/progs/cpumask_failure.c
> index b40b52548ffb..8a2fd596c8a3 100644
> --- a/tools/testing/selftests/bpf/progs/cpumask_failure.c
> +++ b/tools/testing/selftests/bpf/progs/cpumask_failure.c
> @@ -222,3 +222,41 @@ int BPF_PROG(test_invalid_nested_array, struct task_struct *task, u64 clone_flag
>
> return 0;
> }
> +
> +SEC("tp_btf/task_newtask")
> +__failure __msg("type=scalar expected=fp")
> +int BPF_PROG(test_populate_invalid_destination, struct task_struct *task, u64 clone_flags)
> +{
> + struct bpf_cpumask *invalid = (struct bpf_cpumask *)0x123456;
> + u64 bits;
> + int ret;
> +
> + ret = bpf_cpumask_populate((struct cpumask *)invalid, &bits, sizeof(bits));
> + if (!ret)
> + err = 2;
> +
> + return 0;
> +}
> +
> +SEC("tp_btf/task_newtask")
> +__failure __msg("leads to invalid memory access")
> +int BPF_PROG(test_populate_invalid_source, struct task_struct *task, u64 clone_flags)
> +{
> + void *garbage = (void *)0x123456;
> + struct bpf_cpumask *local;
> + int ret;
> +
> + local = create_cpumask();
> + if (!local) {
> + err = 1;
> + return 0;
> + }
> +
> + ret = bpf_cpumask_populate((struct cpumask *)local, garbage, 8);
> + if (!ret)
> + err = 2;
> +
> + bpf_cpumask_release(local);
> +
> + return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c
> index 80ee469b0b60..5dc0fe9940dc 100644
> --- a/tools/testing/selftests/bpf/progs/cpumask_success.c
> +++ b/tools/testing/selftests/bpf/progs/cpumask_success.c
> @@ -757,6 +757,7 @@ int BPF_PROG(test_refcount_null_tracking, struct task_struct *task, u64 clone_fl
> mask1 = bpf_cpumask_create();
> mask2 = bpf_cpumask_create();
>
> +
> if (!mask1 || !mask2)
> goto free_masks_return;
An extra newline.
>
> @@ -770,3 +771,116 @@ int BPF_PROG(test_refcount_null_tracking, struct task_struct *task, u64 clone_fl
> bpf_cpumask_release(mask2);
> return 0;
> }
> +
> +SEC("tp_btf/task_newtask")
> +__success
For tp_btf, bpf_prog_test_run() doesn't run the prog and it just returns
directly, therefore, the prog below is not exercised at all. How about
add test_populate_reject_small_mask into cpumask_success_testcases
firstly, then switch these test cases to use __success() in a following
patch ?
> +int BPF_PROG(test_populate_reject_small_mask, struct task_struct *task, u64 clone_flags)
> +{
> + struct bpf_cpumask *local;
> + u8 toofewbits;
> + int ret;
> +
> + local = create_cpumask();
> + if (!local)
> + return 0;
> +
> + /* The kfunc should prevent this operation */
> + ret = bpf_cpumask_populate((struct cpumask *)local, &toofewbits, sizeof(toofewbits));
> + if (ret != -EACCES)
> + err = 2;
> +
> + bpf_cpumask_release(local);
> +
> + return 0;
> +}
> +
> +/* Mask is guaranteed to be large enough for bpf_cpumask_t. */
> +#define CPUMASK_TEST_MASKLEN (sizeof(cpumask_t))
> +
> +/* Add an extra word for the test_populate_reject_unaligned test. */
> +u64 bits[CPUMASK_TEST_MASKLEN / 8 + 1];
> +extern bool CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS __kconfig __weak;
> +
> +SEC("tp_btf/task_newtask")
> +__success
Same for test_populate_reject_unaligned.
> +int BPF_PROG(test_populate_reject_unaligned, struct task_struct *task, u64 clone_flags)
> +{
> + struct bpf_cpumask *mask;
> + char *src;
> + int ret;
> +
> + /* Skip if unaligned accesses are fine for this arch. */
> + if (CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
> + return 0;
> +
> + mask = bpf_cpumask_create();
> + if (!mask) {
> + err = 1;
> + return 0;
> + }
> +
> + /* Misalign the source array by a byte. */
> + src = &((char *)bits)[1];
> +
> + ret = bpf_cpumask_populate((struct cpumask *)mask, src, CPUMASK_TEST_MASKLEN);
> + if (ret != -EINVAL)
> + err = 2;
> +
> + bpf_cpumask_release(mask);
> +
> + return 0;
> +}
> +
> +
> +SEC("tp_btf/task_newtask")
> +__success
> +int BPF_PROG(test_populate, struct task_struct *task, u64 clone_flags)
> +{
> + struct bpf_cpumask *mask;
> + bool bit;
> + int ret;
> + int i;
> +
> + /* Set only odd bits. */
> + __builtin_memset(bits, 0xaa, CPUMASK_TEST_MASKLEN);
> +
> + mask = bpf_cpumask_create();
> + if (!mask) {
> + err = 1;
> + return 0;
> + }
> +
> + /* Pass the entire bits array, the kfunc will only copy the valid bits. */
> + ret = bpf_cpumask_populate((struct cpumask *)mask, bits, CPUMASK_TEST_MASKLEN);
> + if (ret) {
> + err = 2;
> + goto out;
> + }
> +
> + /*
> + * Test is there to appease the verifier. We cannot directly
> + * access NR_CPUS, the upper bound for nr_cpus, so we infer
> + * it from the size of cpumask_t.
> + */
> + if (nr_cpus < 0 || nr_cpus >= CPUMASK_TEST_MASKLEN * 8) {
> + err = 3;
> + goto out;
> + }
> +
> + bpf_for(i, 0, nr_cpus) {
> + /* Odd-numbered bits should be set, even ones unset. */
> + bit = bpf_cpumask_test_cpu(i, (const struct cpumask *)mask);
> + if (bit == (i % 2 != 0))
> + continue;
> +
> + err = 4;
> + break;
> + }
> +
> +out:
> + bpf_cpumask_release(mask);
> +
> + return 0;
> +}
> +
> +#undef CPUMASK_TEST_MASKLEN
