On Fri, Jun 16, 2023 at 10:18 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> This allows BTF parsing to proceed even if we do not know the
> kind.
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
> tools/lib/bpf/btf.c | 41 ++++++++++++++++++++++++++++++++++-------
> 1 file changed, 34 insertions(+), 7 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index f9f919fdc728..457997c2a43c 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -327,7 +327,35 @@ static int btf_parse_kind_layout_sec(struct btf *btf)
> return 0;
> }
>
> -static int btf_type_size(const struct btf_type *t)
> +/* for unknown kinds, consult kind layout. */
> +static int btf_type_size_unknown(const struct btf *btf, const struct btf_type *t)
> +{
> + int size = sizeof(struct btf_type);
> + struct btf_kind_layout *k = NULL;
> + __u16 vlen = btf_vlen(t);
> + __u8 kind = btf_kind(t);
> +
> + if (btf->kind_layout)
> + k = &btf->kind_layout[kind];
see my suggestion on the previous patch. Let's make this layout
information mandatory internally and always use it consistently.
simpler code, more testing for this new code path
> +
> + if (!k || (void *)k > ((void *)btf->kind_layout + btf->hdr->kind_layout_len)) {
> + pr_debug("Unsupported BTF_KIND: %u\n", btf_kind(t));
> + return -EINVAL;
> + }
> +
> + if (!(k->flags & BTF_KIND_LAYOUT_OPTIONAL)) {
> + /* a required kind, and we do not know about it.. */
> + pr_debug("unknown but required kind: %u\n", kind);
> + return -EINVAL;
> + }
> +
> + size += k->info_sz;
> + size += vlen * k->elem_sz;
> +
> + return size;
> +}
> +
> +static int btf_type_size(const struct btf *btf, const struct btf_type *t)
> {
> const int base_size = sizeof(struct btf_type);
> __u16 vlen = btf_vlen(t);
> @@ -363,8 +391,7 @@ static int btf_type_size(const struct btf_type *t)
> case BTF_KIND_DECL_TAG:
> return base_size + sizeof(struct btf_decl_tag);
> default:
> - pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
> - return -EINVAL;
> + return btf_type_size_unknown(btf, t);
> }
> }
>
> @@ -463,7 +490,7 @@ static int btf_parse_type_sec(struct btf *btf)
> if (btf->swapped_endian)
> btf_bswap_type_base(next_type);
>
> - type_size = btf_type_size(next_type);
> + type_size = btf_type_size(btf, next_type);
> if (type_size < 0)
> return type_size;
> if (next_type + type_size > end_type) {
> @@ -1672,7 +1699,7 @@ int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_t
> struct btf_type *t;
> int sz, err;
>
> - sz = btf_type_size(src_type);
> + sz = btf_type_size(src_btf, src_type);
> if (sz < 0)
> return libbpf_err(sz);
>
> @@ -1753,7 +1780,7 @@ int btf__add_btf(struct btf *btf, const struct btf *src_btf)
> memcpy(t, src_btf->types_data, data_sz);
>
> for (i = 0; i < cnt; i++) {
> - sz = btf_type_size(t);
> + sz = btf_type_size(src_btf, t);
> if (sz < 0) {
> /* unlikely, has to be corrupted src_btf */
> err = sz;
> @@ -4749,7 +4776,7 @@ static int btf_dedup_compact_types(struct btf_dedup *d)
> continue;
>
> t = btf__type_by_id(d->btf, id);
> - len = btf_type_size(t);
> + len = btf_type_size(d->btf, t);
> if (len < 0)
> return len;
>
> --
> 2.39.3
>
