bpf: Factor out verbose_invalid_scalar()

Factor out the function verbose_invalid_scalar() to verbose
print if a scalar is not in a tnum range. There is no
functionality change and the function will be used by
later patch which introduced bpf_for_each_map_elem().
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204922.3884375-1-yhs@fb.com

kernel/bpf/verifier.c

@@ -390,6 +390,24 @@ __printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env,
 	env->prev_linfo = linfo;
 }
 
+static void verbose_invalid_scalar(struct bpf_verifier_env *env,
+				   struct bpf_reg_state *reg,
+				   struct tnum *range, const char *ctx,
+				   const char *reg_name)
+{
+	char tn_buf[48];
+
+	verbose(env, "At %s the register %s ", ctx, reg_name);
+	if (!tnum_is_unknown(reg->var_off)) {
+		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
+		verbose(env, "has value %s", tn_buf);
+	} else {
+		verbose(env, "has unknown scalar value");
+	}
+	tnum_strn(tn_buf, sizeof(tn_buf), *range);
+	verbose(env, " should have been in %s\n", tn_buf);
+}
+
 static bool type_is_pkt_pointer(enum bpf_reg_type type)
 {
 	return type == PTR_TO_PACKET ||
@@ -8455,17 +8473,7 @@ static int check_return_code(struct bpf_verifier_env *env)
 	}
 
 	if (!tnum_in(range, reg->var_off)) {
-		char tn_buf[48];
-
-		verbose(env, "At program exit the register R0 ");
-		if (!tnum_is_unknown(reg->var_off)) {
-			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
-			verbose(env, "has value %s", tn_buf);
-		} else {
-			verbose(env, "has unknown scalar value");
-		}
-		tnum_strn(tn_buf, sizeof(tn_buf), range);
-		verbose(env, " should have been in %s\n", tn_buf);
+		verbose_invalid_scalar(env, reg, &range, "program exit", "R0");
 		return -EINVAL;
 	}