bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG

Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.

After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).

This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].

 [1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
 [2] https://reviews.llvm.org/D111588
 [3] https://reviews.llvm.org/D111199

Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com

6 files changed, 42 insertions, 42 deletions

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 60fbd1c6d466..1f6dea11f600 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -309,8 +309,8 @@ static int btf_type_size(const struct btf_type *t)
 		return base_size + sizeof(struct btf_var);
 	case BTF_KIND_DATASEC:
 		return base_size + vlen * sizeof(struct btf_var_secinfo);
-	case BTF_KIND_TAG:
-		return base_size + sizeof(struct btf_tag);
+	case BTF_KIND_DECL_TAG:
+		return base_size + sizeof(struct btf_decl_tag);
 	default:
 		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
 		return -EINVAL;
@@ -383,8 +383,8 @@ static int btf_bswap_type_rest(struct btf_type *t)
 			v->size = bswap_32(v->size);
 		}
 		return 0;
-	case BTF_KIND_TAG:
-		btf_tag(t)->component_idx = bswap_32(btf_tag(t)->component_idx);
+	case BTF_KIND_DECL_TAG:
+		btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
 		return 0;
 	default:
 		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
@@ -596,7 +596,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 		case BTF_KIND_CONST:
 		case BTF_KIND_RESTRICT:
 		case BTF_KIND_VAR:
-		case BTF_KIND_TAG:
+		case BTF_KIND_DECL_TAG:
 			type_id = t->type;
 			break;
 		case BTF_KIND_ARRAY:
@@ -2569,7 +2569,7 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
 }
 
 /*
- * Append new BTF_KIND_TAG type with:
+ * Append new BTF_KIND_DECL_TAG type with:
  *   - *value* - non-empty/non-NULL string;
  *   - *ref_type_id* - referenced type ID, it might not exist yet;
  *   - *component_idx* - -1 for tagging reference type, otherwise struct/union
@@ -2578,7 +2578,7 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
  *   - >0, type ID of newly added BTF type;
  *   - <0, on error.
  */
-int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
+int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
 		 int component_idx)
 {
 	struct btf_type *t;
@@ -2593,7 +2593,7 @@ int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
 	if (btf_ensure_modifiable(btf))
 		return libbpf_err(-ENOMEM);
 
-	sz = sizeof(struct btf_type) + sizeof(struct btf_tag);
+	sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
 		return libbpf_err(-ENOMEM);
@@ -2603,9 +2603,9 @@ int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
 		return value_off;
 
 	t->name_off = value_off;
-	t->info = btf_type_info(BTF_KIND_TAG, 0, false);
+	t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
 	t->type = ref_type_id;
-	btf_tag(t)->component_idx = component_idx;
+	btf_decl_tag(t)->component_idx = component_idx;
 
 	return btf_commit_type(btf, sz);
 }
@@ -3427,7 +3427,7 @@ static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
 }
 
 /* Calculate type signature hash of INT or TAG. */
-static long btf_hash_int_tag(struct btf_type *t)
+static long btf_hash_int_decl_tag(struct btf_type *t)
 {
 	__u32 info = *(__u32 *)(t + 1);
 	long h;
@@ -3705,8 +3705,8 @@ static int btf_dedup_prep(struct btf_dedup *d)
 			h = btf_hash_common(t);
 			break;
 		case BTF_KIND_INT:
-		case BTF_KIND_TAG:
-			h = btf_hash_int_tag(t);
+		case BTF_KIND_DECL_TAG:
+			h = btf_hash_int_decl_tag(t);
 			break;
 		case BTF_KIND_ENUM:
 			h = btf_hash_enum(t);
@@ -3761,11 +3761,11 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
 	case BTF_KIND_FUNC_PROTO:
 	case BTF_KIND_VAR:
 	case BTF_KIND_DATASEC:
-	case BTF_KIND_TAG:
+	case BTF_KIND_DECL_TAG:
 		return 0;
 
 	case BTF_KIND_INT:
-		h = btf_hash_int_tag(t);
+		h = btf_hash_int_decl_tag(t);
 		for_each_dedup_cand(d, hash_entry, h) {
 			cand_id = (__u32)(long)hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
@@ -4382,13 +4382,13 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 		}
 		break;
 
-	case BTF_KIND_TAG:
+	case BTF_KIND_DECL_TAG:
 		ref_type_id = btf_dedup_ref_type(d, t->type);
 		if (ref_type_id < 0)
 			return ref_type_id;
 		t->type = ref_type_id;
 
-		h = btf_hash_int_tag(t);
+		h = btf_hash_int_decl_tag(t);
 		for_each_dedup_cand(d, hash_entry, h) {
 			cand_id = (__u32)(long)hash_entry->value;
 			cand = btf_type_by_id(d->btf, cand_id);
@@ -4671,7 +4671,7 @@ int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ct
 	case BTF_KIND_TYPEDEF:
 	case BTF_KIND_FUNC:
 	case BTF_KIND_VAR:
-	case BTF_KIND_TAG:
+	case BTF_KIND_DECL_TAG:
 		return visit(&t->type, ctx);
 
 	case BTF_KIND_ARRAY: {
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 864eb51753a1..4011e206e6f7 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -236,7 +236,7 @@ LIBBPF_API int btf__add_datasec_var_info(struct btf *btf, int var_type_id,
 					 __u32 offset, __u32 byte_sz);
 
 /* tag construction API */
-LIBBPF_API int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
+LIBBPF_API int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
 			    int component_idx);
 
 struct btf_dedup_opts {
@@ -426,9 +426,9 @@ static inline bool btf_is_float(const struct btf_type *t)
 	return btf_kind(t) == BTF_KIND_FLOAT;
 }
 
-static inline bool btf_is_tag(const struct btf_type *t)
+static inline bool btf_is_decl_tag(const struct btf_type *t)
 {
-	return btf_kind(t) == BTF_KIND_TAG;
+	return btf_kind(t) == BTF_KIND_DECL_TAG;
 }
 
 static inline __u8 btf_int_encoding(const struct btf_type *t)
@@ -499,10 +499,10 @@ btf_var_secinfos(const struct btf_type *t)
 	return (struct btf_var_secinfo *)(t + 1);
 }
 
-struct btf_tag;
-static inline struct btf_tag *btf_tag(const struct btf_type *t)
+struct btf_decl_tag;
+static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t)
 {
-	return (struct btf_tag *)(t + 1);
+	return (struct btf_decl_tag *)(t + 1);
 }
 
 #ifdef __cplusplus
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index ad6df97295ae..5ef42f0abed1 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -316,7 +316,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d)
 		case BTF_KIND_TYPEDEF:
 		case BTF_KIND_FUNC:
 		case BTF_KIND_VAR:
-		case BTF_KIND_TAG:
+		case BTF_KIND_DECL_TAG:
 			d->type_states[t->type].referenced = 1;
 			break;
 
@@ -584,7 +584,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
 	case BTF_KIND_FUNC:
 	case BTF_KIND_VAR:
 	case BTF_KIND_DATASEC:
-	case BTF_KIND_TAG:
+	case BTF_KIND_DECL_TAG:
 		d->type_states[id].order_state = ORDERED;
 		return 0;
 
@@ -2217,7 +2217,7 @@ static int btf_dump_dump_type_data(struct btf_dump *d,
 	case BTF_KIND_FWD:
 	case BTF_KIND_FUNC:
 	case BTF_KIND_FUNC_PROTO:
-	case BTF_KIND_TAG:
+	case BTF_KIND_DECL_TAG:
 		err = btf_dump_unsupported_data(d, t, id);
 		break;
 	case BTF_KIND_INT:
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ae0889bebe32..63d738654ff6 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -195,8 +195,8 @@ enum kern_feature_id {
 	FEAT_BTF_FLOAT,
 	/* BPF perf link support */
 	FEAT_PERF_LINK,
-	/* BTF_KIND_TAG support */
-	FEAT_BTF_TAG,
+	/* BTF_KIND_DECL_TAG support */
+	FEAT_BTF_DECL_TAG,
 	__FEAT_CNT,
 };
 
@@ -2024,7 +2024,7 @@ static const char *__btf_kind_str(__u16 kind)
 	case BTF_KIND_VAR: return "var";
 	case BTF_KIND_DATASEC: return "datasec";
 	case BTF_KIND_FLOAT: return "float";
-	case BTF_KIND_TAG: return "tag";
+	case BTF_KIND_DECL_TAG: return "decl_tag";
 	default: return "unknown";
 	}
 }
@@ -2524,9 +2524,9 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
 	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
 	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
 	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
-	bool has_tag = kernel_supports(obj, FEAT_BTF_TAG);
+	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
 
-	return !has_func || !has_datasec || !has_func_global || !has_float || !has_tag;
+	return !has_func || !has_datasec || !has_func_global || !has_float || !has_decl_tag;
 }
 
 static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@@ -2535,15 +2535,15 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
 	bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
 	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
 	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
-	bool has_tag = kernel_supports(obj, FEAT_BTF_TAG);
+	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
 	struct btf_type *t;
 	int i, j, vlen;
 
 	for (i = 1; i <= btf__get_nr_types(btf); i++) {
 		t = (struct btf_type *)btf__type_by_id(btf, i);
 
-		if ((!has_datasec && btf_is_var(t)) || (!has_tag && btf_is_tag(t))) {
-			/* replace VAR/TAG with INT */
+		if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
+			/* replace VAR/DECL_TAG with INT */
 			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
 			/*
 			 * using size = 1 is the safest choice, 4 will be too
@@ -4248,7 +4248,7 @@ static int probe_kern_btf_float(void)
 					     strs, sizeof(strs)));
 }
 
-static int probe_kern_btf_tag(void)
+static int probe_kern_btf_decl_tag(void)
 {
 	static const char strs[] = "\0tag";
 	__u32 types[] = {
@@ -4258,7 +4258,7 @@ static int probe_kern_btf_tag(void)
 		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
 		BTF_VAR_STATIC,
 		/* attr */
-		BTF_TYPE_TAG_ENC(1, 2, -1),
+		BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
 	};
 
 	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
@@ -4481,8 +4481,8 @@ static struct kern_feature_desc {
 	[FEAT_PERF_LINK] = {
 		"BPF perf link support", probe_perf_link,
 	},
-	[FEAT_BTF_TAG] = {
-		"BTF_KIND_TAG support", probe_kern_btf_tag,
+	[FEAT_BTF_DECL_TAG] = {
+		"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
 	},
 };
 
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index f270d25e4af3..e6fb1ba49369 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -394,5 +394,5 @@ LIBBPF_0.6.0 {
 		bpf_object__prev_map;
 		bpf_object__prev_program;
 		btf__add_btf;
-		btf__add_tag;
+		btf__add_decl_tag;
 } LIBBPF_0.5.0;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index f7fd3944d46d..f6a5748dd318 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -69,8 +69,8 @@
 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
 #define BTF_TYPE_FLOAT_ENC(name, sz) \
 	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
-#define BTF_TYPE_TAG_ENC(value, type, component_idx) \
-	BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_TAG, 0, 0), type), (component_idx)
+#define BTF_TYPE_DECL_TAG_ENC(value, type, component_idx) \
+	BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_DECL_TAG, 0, 0), type), (component_idx)
 
 #ifndef likely
 #define likely(x) __builtin_expect(!!(x), 1)