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

[Tiezhu Yang]

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.

----->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