Re: [PATCH bpf-next v4 2/2] selftests/bpf: Skip callback tests if jit is disabled in test_verifier

[Song Liu]

On Mon, Jan 15, 2024 at 8:50 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.
>
>   [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable
>   [root@linux bpf]# echo 0 > /proc/sys/kernel/unprivileged_bpf_disabled
>   [root@linux bpf]# ./test_verifier | grep FAIL
>   #106/p inline simple bpf_loop call FAIL
>   #107/p don't inline bpf_loop call, flags non-zero FAIL
>   #108/p don't inline bpf_loop call, callback non-constant FAIL
>   #109/p bpf_loop_inline and a dead func FAIL
>   #110/p bpf_loop_inline stack locations for loop vars FAIL
>   #111/p inline bpf_loop call in a big program FAIL
>   Summary: 768 PASSED, 15 SKIPPED, 6 FAILED
>
> The test log shows that callbacks are not allowed in non-JITed programs,
> interpreter doesn't support them yet, thus these tests should be skipped
> if jit is disabled, copy some check functions from the other places under
> tools directory, and then handle this case in do_test_single().
>
> With this patch:
>
>   [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable
>   [root@linux bpf]# echo 0 > /proc/sys/kernel/unprivileged_bpf_disabled
>   [root@linux bpf]# ./test_verifier | grep FAIL
>   Summary: 768 PASSED, 21 SKIPPED, 0 FAILED
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> ---
>  tools/testing/selftests/bpf/test_verifier.c | 23 +++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index 1a09fc34d093..02c4a0bbdc5e 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -74,6 +74,7 @@
>                     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;
> @@ -1355,6 +1356,16 @@ static bool is_skip_insn(struct bpf_insn *insn)
>         return memcmp(insn, &skip_insn, sizeof(skip_insn)) == 0;
>  }
>
> +static bool is_ldimm64_insn(struct bpf_insn *insn)
> +{
> +       return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
> +}
> +
> +static bool insn_is_pseudo_func(struct bpf_insn *insn)
> +{
> +       return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
> +}
> +

These two functions are duplicated from libbpf_internal.h and libbpf.c.
It will be good to reuse them. We will need something like the following
to include libbpf_internal.h and fix "poisoned" errors.

Thanks,
Song

diff --git i/tools/testing/selftests/bpf/test_verifier.c
w/tools/testing/selftests/bpf/test_verifier.c
index 98107e0452d3..7528a6b41623 100644
--- i/tools/testing/selftests/bpf/test_verifier.c
+++ w/tools/testing/selftests/bpf/test_verifier.c
@@ -41,6 +41,7 @@
 #include "test_btf.h"
 #include "../../../include/linux/filter.h"
 #include "testing_helpers.h"
+#include "bpf/libbpf_internal.h"

 #ifndef ENOTSUPP
 #define ENOTSUPP 524
@@ -1143,8 +1144,8 @@ static void do_test_fixup(struct bpf_test *test,
enum bpf_prog_type prog_type,
                } while (*fixup_map_xskmap);
        }
        if (*fixup_map_stacktrace) {
-               map_fds[12] = create_map(BPF_MAP_TYPE_STACK_TRACE, sizeof(u32),
-                                        sizeof(u64), 1);
+               map_fds[12] = create_map(BPF_MAP_TYPE_STACK_TRACE,
sizeof(__u32),
+                                        sizeof(__u64), 1);
                do {
                        prog[*fixup_map_stacktrace].imm = map_fds[12];
                        fixup_map_stacktrace++;
@@ -1203,7 +1204,7 @@ static void do_test_fixup(struct bpf_test *test,
enum bpf_prog_type prog_type,
        }
        if (*fixup_map_reuseport_array) {
                map_fds[19] = __create_map(BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
-                                          sizeof(u32), sizeof(u64), 1, 0);
+                                          sizeof(__u32), sizeof(__u64), 1, 0);
                do {
                        prog[*fixup_map_reuseport_array].imm = map_fds[19];
                        fixup_map_reuseport_array++;