Re: [PATCH bpf-next v6 3/3] selftests/bpf: Skip callback tests if jit is disabled in test_verifier

[Andrii Nakryiko]

On Mon, Jan 22, 2024 at 7:35 PM Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> wrote:
>
>
>
> On 01/23/2024 09:08 AM, Andrii Nakryiko wrote:
> > On Sun, Jan 21, 2024 at 11:57 PM Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> wrote:
> >>
> >> If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there
> >> exist 6 failed tests.
>
> ...
>
> >>         if (expected_ret == ACCEPT || expected_ret == VERBOSE_ACCEPT) {
> >> +               if (fd_prog < 0 && saved_errno == EINVAL && jit_disabled) {
> >> +                       for (i = 0; i < prog_len; i++, prog++) {
> >> +                               if (!insn_is_pseudo_func(prog))
> >> +                                       continue;
> >> +                               printf("SKIP (callbacks are not allowed in non-JITed programs)\n");
> >> +                               skips++;
> >> +                               goto close_fds;
> >> +                       }
> >> +               }
> >
> > Wouldn't it be better to add an explicit flag to those tests to mark
> > that they require JIT enabled, instead of trying to derive this from
> > analysing their BPF instructions?
>
> Maybe something like this, add test flag F_NEEDS_JIT_ENABLED in
> bpf_loop_inline.c, check the flag and jit_disabled at the beginning
> of do_test_single(), no need to check fd_prog, saved_errno and the other
> conditions, the patch #2 can be removed too.
>
> If you are OK with the following changes, I will send v7 later.
>

Yes, I think this approach is much better, thanks.

> ----->8-----
>
> diff --git a/tools/testing/selftests/bpf/test_verifier.c
> b/tools/testing/selftests/bpf/test_verifier.c
> index 1a09fc34d093..c65915188d7c 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -67,6 +67,7 @@
>
>   #define F_NEEDS_EFFICIENT_UNALIGNED_ACCESS     (1 << 0)
>   #define F_LOAD_WITH_STRICT_ALIGNMENT           (1 << 1)
> +#define F_NEEDS_JIT_ENABLED                    (1 << 2)
>
>   /* need CAP_BPF, CAP_NET_ADMIN, CAP_PERFMON to load progs */
>   #define ADMIN_CAPS (1ULL << CAP_NET_ADMIN |    \
> @@ -74,6 +75,7 @@
>                      1ULL << CAP_BPF)
>   #define UNPRIV_SYSCTL "kernel/unprivileged_bpf_disabled"
>   static bool unpriv_disabled = false;
> +static bool jit_disabled;
>   static int skips;
>   static bool verbose = false;
>   static int verif_log_level = 0;
> @@ -1524,6 +1526,13 @@ static void do_test_single(struct bpf_test *test,
> bool unpriv,
>          __u32 pflags;
>          int i, err;
>
> +       if ((test->flags & F_NEEDS_JIT_ENABLED) && jit_disabled) {
> +               printf("SKIP (callbacks are not allowed in non-JITed
> programs)\n");
> +               skips++;
> +               sched_yield();
> +               return;
> +       }
> +
>          fd_prog = -1;
>          for (i = 0; i < MAX_NR_MAPS; i++)
>                  map_fds[i] = -1;
> @@ -1844,6 +1853,8 @@ int main(int argc, char **argv)
>                  return EXIT_FAILURE;
>          }
>
> +       jit_disabled = !is_jit_enabled();
> +
>          /* Use libbpf 1.0 API mode */
>          libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
>
> diff --git a/tools/testing/selftests/bpf/verifier/bpf_loop_inline.c
> b/tools/testing/selftests/bpf/verifier/bpf_loop_inline.c
> index a535d41dc20d..59125b22ae39 100644
> --- a/tools/testing/selftests/bpf/verifier/bpf_loop_inline.c
> +++ b/tools/testing/selftests/bpf/verifier/bpf_loop_inline.c
> @@ -57,6 +57,7 @@
>          .expected_insns = { PSEUDO_CALL_INSN() },
>          .unexpected_insns = { HELPER_CALL_INSN() },
>          .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> +       .flags = F_NEEDS_JIT_ENABLED,
>          .result = ACCEPT,
>          .runs = 0,
>          .func_info = { { 0, MAIN_TYPE }, { 12, CALLBACK_TYPE } },
> @@ -90,6 +91,7 @@
>          .expected_insns = { HELPER_CALL_INSN() },
>          .unexpected_insns = { PSEUDO_CALL_INSN() },
>          .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> +       .flags = F_NEEDS_JIT_ENABLED,
>          .result = ACCEPT,
>          .runs = 0,
>          .func_info = { { 0, MAIN_TYPE }, { 16, CALLBACK_TYPE } },
> @@ -127,6 +129,7 @@
>          .expected_insns = { HELPER_CALL_INSN() },
>          .unexpected_insns = { PSEUDO_CALL_INSN() },
>          .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> +       .flags = F_NEEDS_JIT_ENABLED,
>          .result = ACCEPT,
>          .runs = 0,
>          .func_info = {
> @@ -165,6 +168,7 @@
>          .expected_insns = { PSEUDO_CALL_INSN() },
>          .unexpected_insns = { HELPER_CALL_INSN() },
>          .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> +       .flags = F_NEEDS_JIT_ENABLED,
>          .result = ACCEPT,
>          .runs = 0,
>          .func_info = {
> @@ -235,6 +239,7 @@
>          },
>          .unexpected_insns = { HELPER_CALL_INSN() },
>          .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> +       .flags = F_NEEDS_JIT_ENABLED,
>          .result = ACCEPT,
>          .func_info = {
>                  { 0, MAIN_TYPE },
> @@ -252,6 +257,7 @@
>          .unexpected_insns = { HELPER_CALL_INSN() },
>          .result = ACCEPT,
>          .prog_type = BPF_PROG_TYPE_TRACEPOINT,
> +       .flags = F_NEEDS_JIT_ENABLED,
>          .func_info = { { 0, MAIN_TYPE }, { 16, CALLBACK_TYPE } },
>          .func_info_cnt = 2,
>          BTF_TYPES
>
> Thanks,
> Tiezhu
>