• Kumar Kartikeya Dwivedi's avatar
    bpf: Refactor kptr_off_tab into btf_record · aa3496ac
    Kumar Kartikeya Dwivedi authored
    To prepare the BPF verifier to handle special fields in both map values
    and program allocated types coming from program BTF, we need to refactor
    the kptr_off_tab handling code into something more generic and reusable
    across both cases to avoid code duplication.
    
    Later patches also require passing this data to helpers at runtime, so
    that they can work on user defined types, initialize them, destruct
    them, etc.
    
    The main observation is that both map values and such allocated types
    point to a type in program BTF, hence they can be handled similarly. We
    can prepare a field metadata table for both cases and store them in
    struct bpf_map or struct btf depending on the use case.
    
    Hence, refactor the code into generic btf_record and btf_field member
    structs. The btf_record represents the fields of a specific btf_type in
    user BTF. The cnt indicates the number of special fields we successfully
    recognized, and field_mask is a bitmask of fields that were found, to
    enable quick determination of availability of a certain field.
    
    Subsequently, refactor the rest of the code to work with these generic
    types, remove assumptions about kptr and kptr_off_tab, rename variables
    to more meaningful names, etc.
    Signed-off-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
    Link: https://lore.kernel.org/r/20221103191013.1236066-7-memxor@gmail.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
    aa3496ac
verifier.c 438 KB