On Fri, Feb 4, 2022 at 2:05 PM Mauricio Vásquez <mauricio@xxxxxxxxxx> wrote:
>
> The correct formula to get all possible values is
> ((__LIBBPF_STRICT_LAST - 1) * 2 - 1) as stated in
> libbpf_set_strict_mode().
>
> Fixes: 93b8952d223a ("libbpf: deprecate legacy BPF map definitions")
>
> Signed-off-by: Mauricio Vásquez <mauricio@xxxxxxxxxx>
> ---
> tools/bpf/bpftool/main.c | 6 +++++-
> tools/testing/selftests/bpf/prog_tests/btf.c | 10 ++++++++--
please split changes to bpftool and separately selftests/bpf (and in
v2 you'll have a separate libbpf patch as well).
> 2 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
> index 9d01fa9de033..c5b27e41d1e9 100644
> --- a/tools/bpf/bpftool/main.c
> +++ b/tools/bpf/bpftool/main.c
> @@ -483,8 +483,12 @@ int main(int argc, char **argv)
> /* Allow legacy map definitions for skeleton generation.
> * It will still be rejected if users use LIBBPF_STRICT_ALL
> * mode for loading generated skeleton.
> + *
> + * __LIBBPF_STRICT_LAST is the last power-of-2 value used + 1, so to
> + * get all possible values we compensate last +1, and then (2*x - 1)
> + * to get the bit mask
> */
> - mode = (__LIBBPF_STRICT_LAST - 1) & ~LIBBPF_STRICT_MAP_DEFINITIONS;
> + mode = ((__LIBBPF_STRICT_LAST - 1) * 2 - 1) & ~LIBBPF_STRICT_MAP_DEFINITIONS;
> ret = libbpf_set_strict_mode(mode);
> if (ret)
> p_err("failed to enable libbpf strict mode: %d", ret);
> diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
> index 14f9b6136794..90d5cd4f504c 100644
> --- a/tools/testing/selftests/bpf/prog_tests/btf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/btf.c
> @@ -4533,6 +4533,7 @@ static void do_test_file(unsigned int test_num)
> struct btf_ext *btf_ext = NULL;
> struct bpf_prog_info info = {};
> struct bpf_object *obj = NULL;
> + enum libbpf_strict_mode mode;
> struct bpf_func_info *finfo;
> struct bpf_program *prog;
> __u32 info_len, rec_size;
> @@ -4560,8 +4561,13 @@ static void do_test_file(unsigned int test_num)
> has_btf_ext = btf_ext != NULL;
> btf_ext__free(btf_ext);
>
> - /* temporary disable LIBBPF_STRICT_MAP_DEFINITIONS to test legacy maps */
> - libbpf_set_strict_mode((__LIBBPF_STRICT_LAST - 1) & ~LIBBPF_STRICT_MAP_DEFINITIONS);
> + /* temporary disable LIBBPF_STRICT_MAP_DEFINITIONS to test legacy maps
> + * __LIBBPF_STRICT_LAST is the last power-of-2 value used + 1, so to
> + * get all possible values we compensate last +1, and then (2*x - 1)
> + * to get the bit mask
> + */
> + mode = ((__LIBBPF_STRICT_LAST - 1) * 2 - 1) & ~LIBBPF_STRICT_MAP_DEFINITIONS
> + libbpf_set_strict_mode(mode);
> obj = bpf_object__open(test->file);
> err = libbpf_get_error(obj);
> if (CHECK(err, "obj: %d", err))
> --
> 2.25.1
>
