bpf: don't emit warnings intended for global subprogs for static subprogs

When btf_prepare_func_args() was generalized to handle both static and
global subprogs, a few warnings/errors that are meant only for global
subprog cases started to be emitted for static subprogs, where they are
sort of expected and irrelavant.

Stop polutting verifier logs with irrelevant scary-looking messages.

Fixes: e26080d0 ("bpf: prepare btf_prepare_func_args() for handling static subprogs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240202190529.2374377-4-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/btf.c

@@ -7122,6 +7122,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
 	args = (const struct btf_param *)(t + 1);
 	nargs = btf_type_vlen(t);
 	if (nargs > MAX_BPF_FUNC_REG_ARGS) {
+		if (!is_global)
+			return -EINVAL;
 		bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
 			tname, nargs, MAX_BPF_FUNC_REG_ARGS);
 		return -EINVAL;
@@ -7131,6 +7133,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
 	while (btf_type_is_modifier(t))
 		t = btf_type_by_id(btf, t->type);
 	if (!btf_type_is_int(t) && !btf_is_any_enum(t)) {
+		if (!is_global)
+			return -EINVAL;
 		bpf_log(log,
 			"Global function %s() doesn't return scalar. Only those are supported.\n",
 			tname);
@@ -7251,6 +7255,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
 			sub->args[i].arg_type = ARG_ANYTHING;
 			continue;
 		}
+		if (!is_global)
+			return -EINVAL;
 		bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
 			i, btf_type_str(t), tname);
 		return -EINVAL;