Commit f4b4eee6 authored Mar 02, 2023 by Andrii Nakryiko Committed by Alexei Starovoitov Mar 04, 2023

bpf: add support for fixed-size memory pointer returns for kfuncs



Support direct fixed-size (and for now, read-only) memory access when
kfunc's return type is a pointer to non-struct type. Calculate type size
and let BPF program access that many bytes directly. This is crucial for
numbers iterator.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230302235015.2044271-13-andrii@kernel.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent a461f5ad

kernel/bpf/verifier.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -10336,6 +10336,14 @@ static int check_kfunc_call(struct bpf_verifier_env env, struct bpf_insn insn,
		return -EFAULT;
		}
		} else if (!__btf_type_is_struct(ptr_type)) {
		if (!meta.r0_size) {
		__u32 sz;

		if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) {
		meta.r0_size = sz;
		meta.r0_rdonly = true;
		}
		}
		if (!meta.r0_size) {
		ptr_type_name = btf_name_by_offset(desc_btf,
		ptr_type->name_off);