bpf: Add BTF_KIND_DECL_TAG typedef support

mainline inclusion
from mainline-5.16-rc1
commit bd16dee6
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bd16dee66ae4de3f1726c69ac901d2b7a53b0c86

-------------------------------------------------

The llvm patches ([1], [2]) added support to attach btf_decl_tag
attributes to typedef declarations. This patch added
support in kernel.

  [1] https://reviews.llvm.org/D110127
  [2] https://reviews.llvm.org/D112259Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211021195628.4018847-1-yhs@fb.com
(cherry picked from commit bd16dee6)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

kernel/bpf/btf.c

@@ -467,7 +467,7 @@ static bool btf_type_is_decl_tag(const struct btf_type *t)
 static bool btf_type_is_decl_tag_target(const struct btf_type *t)
 {
 	return btf_type_is_func(t) || btf_type_is_struct(t) ||
-	       btf_type_is_var(t);
+	       btf_type_is_var(t) || btf_type_is_typedef(t);
 }
 
 u32 btf_nr_types(const struct btf *btf)
@@ -3759,7 +3759,7 @@ static int btf_decl_tag_resolve(struct btf_verifier_env *env,
 
 	component_idx = btf_type_decl_tag(t)->component_idx;
 	if (component_idx != -1) {
-		if (btf_type_is_var(next_type)) {
+		if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
 			btf_verifier_log_type(env, v->t, "Invalid component_idx");
 			return -EINVAL;
 		}