bpf, offload: Reorder offload callback 'prepare' in verifier

Commit 4976b718 ("bpf: Introduce pseudo_btf_id") switched the
order of resolve_pseudo_ldimm(), in which some pseudo instructions
are rewritten. Thus those rewritten instructions cannot be passed
to driver via 'prepare' offload callback.

Reorder the 'prepare' offload callback to fix it.

Fixes: 4976b718 ("bpf: Introduce pseudo_btf_id")
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210520085834.15023-1-simon.horman@netronome.com

kernel/bpf/verifier.c

@@ -13368,12 +13368,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 	if (is_priv)
 		env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
 
-	if (bpf_prog_is_dev_bound(env->prog->aux)) {
-		ret = bpf_prog_offload_verifier_prep(env->prog);
-		if (ret)
-			goto skip_full_check;
-	}
-
 	env->explored_states = kvcalloc(state_htab_size(env),
 				       sizeof(struct bpf_verifier_state_list *),
 				       GFP_USER);
@@ -13401,6 +13395,12 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 	if (ret < 0)
 		goto skip_full_check;
 
+	if (bpf_prog_is_dev_bound(env->prog->aux)) {
+		ret = bpf_prog_offload_verifier_prep(env->prog);
+		if (ret)
+			goto skip_full_check;
+	}
+
 	ret = check_cfg(env);
 	if (ret < 0)
 		goto skip_full_check;