Re: [PATCH bpf-next v2 2/9] bpftool: Honor BPF_CORE_TYPE_MATCHES relocation

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Jun 23, 2022 at 2:22 PM Daniel Müller <deso@xxxxxxxxxx> wrote:
>
> bpftool needs to know about the newly introduced BPF_CORE_TYPE_MATCHES
> relocation for its 'gen min_core_btf' command to work properly in the
> present of this relocation.
> Specifically, we need to make sure to mark types and fields so that they
> are present in the minimized BTF for "type match" checks to work out.
> However, contrary to the existing btfgen_record_field_relo, we need to
> rely on the BTF -- and not the spec -- to find fields. With this change
> we handle this new variant correctly. The functionality will be tested
> with follow on changes to BPF selftests, which already run against a
> minimized BTF created with bpftool.
>
> Cc: Quentin Monnet <quentin@xxxxxxxxxxxxx>
> Signed-off-by: Daniel Müller <deso@xxxxxxxxxx>
> ---
>  tools/bpf/bpftool/gen.c | 107 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 107 insertions(+)
>
> diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
> index 480cbd8..6cd0ed 100644
> --- a/tools/bpf/bpftool/gen.c
> +++ b/tools/bpf/bpftool/gen.c
> @@ -1856,6 +1856,111 @@ static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_sp
>         return 0;
>  }
>
> +/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
> + * this function does not rely on the target spec for inferring members, but
> + * uses the associated BTF.
> + *
> + * The `behind_ptr` argument is used to stop marking of composite types reached
> + * through a pointer. This way, we keep can keep BTF size in check while
> + * providing reasonable match semantics.
> + */
> +static int btfgen_mark_types_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
> +{
> +       const struct btf_type *btf_type;
> +       struct btf *btf = info->src_btf;
> +       struct btf_type *cloned_type;
> +       int i, err;
> +
> +       if (type_id == 0)
> +               return 0;
> +
> +       btf_type = btf__type_by_id(btf, type_id);
> +       /* mark type on cloned BTF as used */
> +       cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
> +       cloned_type->name_off = MARKED;
> +
> +       switch (btf_kind(btf_type)) {
> +       case BTF_KIND_UNKN:
> +       case BTF_KIND_INT:
> +       case BTF_KIND_FLOAT:
> +       case BTF_KIND_ENUM:
> +       case BTF_KIND_ENUM64:
> +               break;
> +       case BTF_KIND_STRUCT:
> +       case BTF_KIND_UNION: {
> +               struct btf_member *m = btf_members(btf_type);
> +               __u16 vlen = btf_vlen(btf_type);
> +
> +               if (behind_ptr)
> +                       break;
> +
> +               for (i = 0; i < vlen; i++, m++) {
> +                       /* mark member */
> +                       btfgen_mark_member(info, type_id, i);
> +
> +                       /* mark member's type */
> +                       err = btfgen_mark_types_match(info, m->type, false);
> +                       if (err)
> +                               return err;
> +               }
> +               break;
> +       }
> +       case BTF_KIND_CONST:
> +       case BTF_KIND_FWD:
> +       case BTF_KIND_VOLATILE:
> +       case BTF_KIND_TYPEDEF:

BTF_KIND_RESTRICT is missing?


> +               return btfgen_mark_types_match(info, btf_type->type, false);
> +       case BTF_KIND_PTR:
> +               return btfgen_mark_types_match(info, btf_type->type, true);
> +       case BTF_KIND_ARRAY: {
> +               struct btf_array *array;
> +
> +               array = btf_array(btf_type);
> +               /* mark array type */
> +               err = btfgen_mark_types_match(info, array->type, false);
> +               /* mark array's index type */
> +               err = err ? : btfgen_mark_types_match(info, array->index_type, false);
> +               if (err)
> +                       return err;
> +               break;
> +       }

[...]




[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux