On Mon, Nov 29, 2021 at 05:29:47PM -0800, Hao Luo wrote:
>
> +
> struct bpf_reg_types {
> const enum bpf_reg_type types[10];
> u32 *btf_id;
> +
> + /* Certain types require customized type matching function. */
> + bool (*type_match_fn)(enum bpf_arg_type arg_type,
> + enum bpf_reg_type type,
> + enum bpf_reg_type expected);
> };
>
> static const struct bpf_reg_types map_key_value_types = {
> @@ -5013,6 +5019,19 @@ static const struct bpf_reg_types btf_id_sock_common_types = {
> };
> #endif
>
> +static bool mem_type_match(enum bpf_arg_type arg_type,
> + enum bpf_reg_type type, enum bpf_reg_type expected)
> +{
> + /* If arg_type is tagged with MEM_RDONLY, type is compatible with both
> + * RDONLY and RDWR mem, fold the MEM_RDONLY flag in 'type' before
> + * comparison.
> + */
> + if ((arg_type & MEM_RDONLY) != 0)
> + type &= ~MEM_RDONLY;
> +
> + return type == expected;
> +}
> +
> static const struct bpf_reg_types mem_types = {
> .types = {
> PTR_TO_STACK,
> @@ -5022,8 +5041,8 @@ static const struct bpf_reg_types mem_types = {
> PTR_TO_MAP_VALUE,
> PTR_TO_MEM,
> PTR_TO_BUF,
> - PTR_TO_BUF | MEM_RDONLY,
> },
> + .type_match_fn = mem_type_match,
why add a callback for this logic?
Isn't it a universal rule for MEM_RDONLY?
