On Mon, Oct 23, 2023 at 03:00:29PM -0700, Dave Marchevsky wrote:
SNIP
> - ret = btf_maybe_find_kptr(btf, member_type, off, srch);
> + ret = btf_find_aggregate_field(btf, member_type, srch,
> + struct_field_off + off,
> + rec);
> if (ret < 0)
> return ret;
> continue;
> @@ -3541,15 +3587,17 @@ static int btf_find_struct_field(const struct btf *btf,
> case BPF_LIST_NODE:
> case BPF_RB_NODE:
> case BPF_REFCOUNT:
> - ret = btf_find_struct(btf, member_type, off, sz, field_type,
> - srch);
> + ret = btf_find_struct(btf, member_type,
> + struct_field_off + off,
> + sz, field_type, srch);
> if (ret < 0)
> return ret;
> break;
> case BPF_LIST_HEAD:
> case BPF_RB_ROOT:
> ret = btf_find_graph_root(btf, t, member_type,
> - i, off, sz, srch, field_type);
> + i, struct_field_off + off, sz,
> + srch, field_type);
> if (ret < 0)
> return ret;
> break;
> @@ -3566,6 +3614,82 @@ static int btf_find_struct_field(const struct btf *btf,
> return srch->idx;
> }
>
> +static int btf_flatten_array_field(const struct btf *btf,
> + const struct btf_type *t,
> + struct btf_field_info_search *srch,
> + int array_field_off, int rec)
> +{
> + int ret, start_idx, elem_field_cnt;
> + const struct btf_type *elem_type;
> + struct btf_field_info *info;
> + u32 i, j, off, nelems;
> +
> + if (!btf_type_is_array(t))
> + return -EINVAL;
seems this check is not needed, it's called only for
btf_type_is_array(t)
> + nelems = __multi_dim_elem_type_nelems(btf, t, &elem_type);
> + if (!nelems || !__btf_type_is_struct(elem_type))
> + return srch->idx;
> +
> + start_idx = srch->idx;
> + ret = btf_find_struct_field(btf, elem_type, srch, array_field_off + off, rec);
> + if (ret < 0)
> + return ret;
> +
> + /* No btf_field_info's added */
> + if (srch->idx == start_idx)
> + return srch->idx;
> +
> + elem_field_cnt = srch->idx - start_idx;
> + info = __next_field_infos(srch, elem_field_cnt * (nelems - 1));
> + if (IS_ERR_OR_NULL(info))
> + return PTR_ERR(info);
> +
> + /* Array elems after the first can copy first elem's btf_field_infos
> + * and adjust offset
> + */
> + for (i = 1; i < nelems; i++) {
> + memcpy(info, &srch->infos[start_idx],
> + elem_field_cnt * sizeof(struct btf_field_info));
> + for (j = 0; j < elem_field_cnt; j++) {
> + info->off += (i * elem_type->size);
> + info++;
> + }
> + }
> + return srch->idx;
> +}
> +
> +static int btf_find_aggregate_field(const struct btf *btf,
> + const struct btf_type *t,
> + struct btf_field_info_search *srch,
> + int field_off, int rec)
> +{
> + u32 orig_field_mask;
> + int ret;
> +
> + /* Dig up to 4 levels deep */
> + if (rec >= 4)
> + return -E2BIG;
do we need to fails in here? should we just stop descend?
and continue the search in upper layers
> +
> + orig_field_mask = srch->field_mask;
> + srch->field_mask &= BPF_KPTR;
> +
> + if (!srch->field_mask) {
> + ret = 0;
> + goto reset_field_mask;
> + }
could this be just
if (!(srch->field_mask & BPF_KPTR))
return 0;
but I don't understand why there's the BPF_KPTR restriction in here
jirka
> +
> + if (__btf_type_is_struct(t))
> + ret = btf_find_struct_field(btf, t, srch, field_off, rec + 1);
> + else if (btf_type_is_array(t))
> + ret = btf_flatten_array_field(btf, t, srch, field_off, rec + 1);
> + else
> + ret = -EINVAL;
> +
> +reset_field_mask:
> + srch->field_mask = orig_field_mask;
> + return ret;
> +}
> +
> static int __datasec_vsi_check_align_sz(const struct btf_var_secinfo *vsi,
> enum btf_field_type field_type,
> u32 expected_sz)
> @@ -3605,10 +3729,19 @@ static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
> * btf_maybe_find_kptr will find actual kptr type
> */
> sz = btf_field_type_size(BPF_KPTR_REF);
> - if (__datasec_vsi_check_align_sz(vsi, BPF_KPTR_REF, sz))
> + if (srch->field_mask & BPF_KPTR &&
> + !__datasec_vsi_check_align_sz(vsi, BPF_KPTR_REF, sz)) {
> + ret = btf_maybe_find_kptr(btf, var_type, off, srch);
> + if (ret < 0)
> + return ret;
> + if (ret == BTF_FIELD_FOUND)
> + continue;
> + }
> +
> + if (!(btf_type_is_array(var_type) || __btf_type_is_struct(var_type)))
> continue;
>
> - ret = btf_maybe_find_kptr(btf, var_type, off, srch);
> + ret = btf_find_aggregate_field(btf, var_type, srch, off, 0);
> if (ret < 0)
> return ret;
> continue;
> @@ -3655,7 +3788,7 @@ static int btf_find_field(const struct btf *btf, const struct btf_type *t,
> struct btf_field_info_search *srch)
> {
> if (__btf_type_is_struct(t))
> - return btf_find_struct_field(btf, t, srch);
> + return btf_find_struct_field(btf, t, srch, 0, 0);
> else if (btf_type_is_datasec(t))
> return btf_find_datasec_var(btf, t, srch);
> return -EINVAL;
> --
> 2.34.1
>
>
