Commit a2598045 authored by Andrea Terzolo's avatar Andrea Terzolo Committed by Alexei Starovoitov
Browse files

bpf: clarify a misleading verifier error message 



The current verifier error message states that tail_calls are not
allowed in non-JITed programs with BPF-to-BPF calls. While this is
accurate, it is not the only scenario where this restriction applies.
Some architectures do not support this feature combination even when
programs are JITed. This update improves the error message to better
reflect these limitations.

Suggested-by: default avatarShung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: default avatarAndrea Terzolo <andreaterzolo3@gmail.com>
Acked-by: default avatarShung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20250318083551.8192-1-andreaterzolo3@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 6ca21620

kernel/bpf/verifier.c

+1 −1
Original line number Diff line number Diff line
@@ -9887,7 +9887,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, 
		if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)

			goto error;

		if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {

			verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");

			verbose(env, "mixing of tail_calls and bpf-to-bpf calls is not supported\n");

			return -EINVAL;

		}

		break;