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The following kfuncs currently accept void *meta__ign argument: * bpf_obj_new_impl * bpf_obj_drop_impl * bpf_percpu_obj_new_impl * bpf_percpu_obj_drop_impl * bpf_refcount_acquire_impl * bpf_list_push_back_impl * bpf_list_push_front_impl * bpf_rbtree_add_impl The __ign suffix is an indicator for the verifier to skip the argument in check_kfunc_args(). Then, in fixup_kfunc_call() the verifier may set the value of this argument to struct btf_struct_meta * kptr_struct_meta from insn_aux_data. BPF programs must pass a dummy NULL value when calling these kfuncs. Additionally, the list and rbtree _impl kfuncs also accept an implicit u64 argument, which doesn't require __ign suffix because it's a scalar, and BPF programs explicitly pass 0. Add new kfuncs with KF_IMPLICIT_ARGS [1], that correspond to each _impl kfunc accepting meta__ign. The existing _impl kfuncs remain unchanged for backwards compatibility. To support this, add "btf_struct_meta" to the list of recognized implicit argument types in resolve_btfids. Implement is_kfunc_arg_implicit() in the verifier, that determines implicit args by inspecting both a non-_impl BTF prototype of the kfunc. Update the special_kfunc_list in the verifier and relevant checks to support both the old _impl and the new KF_IMPLICIT_ARGS variants of btf_struct_meta users. [1] https://lore.kernel.org/bpf/20260120222638.3976562-1-ihor.solodrai@linux.dev/ Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20260327203241.3365046-1-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>