diff mbox series

[bpf-next,v2,04/11] libbpf: add support for BTF_KIND_TAG

Message ID 20210913155145.3726307-1-yhs@fb.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf: add support for new btf kind BTF_KIND_TAG | expand

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Commit Message

Yonghong Song Sept. 13, 2021, 3:51 p.m. UTC 
Add BTF_KIND_TAG support for parsing and dedup.
Also added sanitization for BTF_KIND_TAG. If BTF_KIND_TAG is not
supported in the kernel, sanitize it to INTs.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/lib/bpf/btf.c             | 69 +++++++++++++++++++++++++++++++++
 tools/lib/bpf/btf.h             | 15 +++++++
 tools/lib/bpf/btf_dump.c        |  3 ++
 tools/lib/bpf/libbpf.c          | 31 +++++++++++++--
 tools/lib/bpf/libbpf.map        |  5 +++
 tools/lib/bpf/libbpf_internal.h |  2 +
 6 files changed, 122 insertions(+), 3 deletions(-)

Comments

Andrii Nakryiko Sept. 14, 2021, 5:15 a.m. UTC | #1 
On Mon, Sep 13, 2021 at 8:51 AM Yonghong Song <yhs@fb.com> wrote:
>
> Add BTF_KIND_TAG support for parsing and dedup.
> Also added sanitization for BTF_KIND_TAG. If BTF_KIND_TAG is not
> supported in the kernel, sanitize it to INTs.
>
> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---
>  tools/lib/bpf/btf.c             | 69 +++++++++++++++++++++++++++++++++
>  tools/lib/bpf/btf.h             | 15 +++++++
>  tools/lib/bpf/btf_dump.c        |  3 ++
>  tools/lib/bpf/libbpf.c          | 31 +++++++++++++--
>  tools/lib/bpf/libbpf.map        |  5 +++
>  tools/lib/bpf/libbpf_internal.h |  2 +
>  6 files changed, 122 insertions(+), 3 deletions(-)
>

Just a few small nits.

[...]

> @@ -2440,6 +2446,49 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
>         return 0;
>  }
>
> +/*
> + * Append new BTF_KIND_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
> + *     member or function argument index;
> + * Returns:
> + *   - >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 component_idx)
> +{
> +       bool for_ref_type = false;

leftovers from the previous revision? let's just use 0 for kflag argument below

> +       struct btf_type *t;
> +       int sz, value_off;
> +
> +       if (!value || !value[0] || component_idx < -1)
> +               return libbpf_err(-EINVAL);
> +
> +       if (validate_type_id(ref_type_id))
> +               return libbpf_err(-EINVAL);
> +
> +       if (btf_ensure_modifiable(btf))
> +               return libbpf_err(-ENOMEM);
> +
> +       sz = sizeof(struct btf_type) + sizeof(struct btf_tag);
> +       t = btf_add_type_mem(btf, sz);
> +       if (!t)
> +               return libbpf_err(-ENOMEM);
> +
> +       value_off = btf__add_str(btf, value);
> +       if (value_off < 0)
> +               return value_off;
> +
> +       t->name_off = value_off;
> +       t->info = btf_type_info(BTF_KIND_TAG, 0, for_ref_type);
> +       t->type = ref_type_id;
> +       ((struct btf_tag *)(t + 1))->component_idx = component_idx;

nit: btf_tag(t)->component_idx

> +
> +       return btf_commit_type(btf, sz);
> +}
> +
>  struct btf_ext_sec_setup_param {
>         __u32 off;
>         __u32 len;

[...]

> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 8f579c6666b2..4a62ef714562 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -195,6 +195,8 @@ enum kern_feature_id {
>         FEAT_BTF_FLOAT,
>         /* BPF perf link support */
>         FEAT_PERF_LINK,
> +       /* BTF_KIND_ATTR support */

s/BTF_KIND_ATTR/BTF_KIND_TAG/

> +       FEAT_BTF_TAG,
>         __FEAT_CNT,
>  };
>

[...]

>  static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index bbc53bb25f68..9e649cf9e771 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -386,3 +386,8 @@ LIBBPF_0.5.0 {
>                 btf_dump__dump_type_data;
>                 libbpf_set_strict_mode;
>  } LIBBPF_0.4.0;
> +
> +LIBBPF_0.6.0 {
> +       global:
> +               btf__add_tag;
> +} LIBBPF_0.5.0;

you'll need a rebase for this due to my patch for libbpf_version.h, sorry

> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> index 4f6ff5c23695..ceb0c98979bc 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -69,6 +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)
>
>  #ifndef likely
>  #define likely(x) __builtin_expect(!!(x), 1)
> --
> 2.30.2
>
Yonghong Song Sept. 14, 2021, 4:42 p.m. UTC | #2 
On 9/13/21 10:15 PM, Andrii Nakryiko wrote:
> On Mon, Sep 13, 2021 at 8:51 AM Yonghong Song <yhs@fb.com> wrote:
>>
>> Add BTF_KIND_TAG support for parsing and dedup.
>> Also added sanitization for BTF_KIND_TAG. If BTF_KIND_TAG is not
>> supported in the kernel, sanitize it to INTs.
>>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>> ---
>>   tools/lib/bpf/btf.c             | 69 +++++++++++++++++++++++++++++++++
>>   tools/lib/bpf/btf.h             | 15 +++++++
>>   tools/lib/bpf/btf_dump.c        |  3 ++
>>   tools/lib/bpf/libbpf.c          | 31 +++++++++++++--
>>   tools/lib/bpf/libbpf.map        |  5 +++
>>   tools/lib/bpf/libbpf_internal.h |  2 +
>>   6 files changed, 122 insertions(+), 3 deletions(-)
>>
> 
> Just a few small nits.

Ack for all nits. All these are indeed missed leftovers from previous 
patchset/changes.

> 
> [...]
> 
>> @@ -2440,6 +2446,49 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
>>          return 0;
>>   }
>>
>> +/*
>> + * Append new BTF_KIND_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
>> + *     member or function argument index;
>> + * Returns:
>> + *   - >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 component_idx)
>> +{
>> +       bool for_ref_type = false;
> 
> leftovers from the previous revision? let's just use 0 for kflag argument below
> 
>> +       struct btf_type *t;
>> +       int sz, value_off;
>> +
>> +       if (!value || !value[0] || component_idx < -1)
>> +               return libbpf_err(-EINVAL);
>> +
>> +       if (validate_type_id(ref_type_id))
>> +               return libbpf_err(-EINVAL);
>> +
>> +       if (btf_ensure_modifiable(btf))
>> +               return libbpf_err(-ENOMEM);
>> +
>> +       sz = sizeof(struct btf_type) + sizeof(struct btf_tag);
>> +       t = btf_add_type_mem(btf, sz);
>> +       if (!t)
>> +               return libbpf_err(-ENOMEM);
>> +
>> +       value_off = btf__add_str(btf, value);
>> +       if (value_off < 0)
>> +               return value_off;
>> +
>> +       t->name_off = value_off;
>> +       t->info = btf_type_info(BTF_KIND_TAG, 0, for_ref_type);
>> +       t->type = ref_type_id;
>> +       ((struct btf_tag *)(t + 1))->component_idx = component_idx;
> 
> nit: btf_tag(t)->component_idx
> 
>> +
>> +       return btf_commit_type(btf, sz);
>> +}
>> +
>>   struct btf_ext_sec_setup_param {
>>          __u32 off;
>>          __u32 len;
> 
> [...]
> 
>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> index 8f579c6666b2..4a62ef714562 100644
>> --- a/tools/lib/bpf/libbpf.c
>> +++ b/tools/lib/bpf/libbpf.c
>> @@ -195,6 +195,8 @@ enum kern_feature_id {
>>          FEAT_BTF_FLOAT,
>>          /* BPF perf link support */
>>          FEAT_PERF_LINK,
>> +       /* BTF_KIND_ATTR support */
> 
> s/BTF_KIND_ATTR/BTF_KIND_TAG/
> 
>> +       FEAT_BTF_TAG,
>>          __FEAT_CNT,
>>   };
>>
> 
> [...]
> 
>>   static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
>> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
>> index bbc53bb25f68..9e649cf9e771 100644
>> --- a/tools/lib/bpf/libbpf.map
>> +++ b/tools/lib/bpf/libbpf.map
>> @@ -386,3 +386,8 @@ LIBBPF_0.5.0 {
>>                  btf_dump__dump_type_data;
>>                  libbpf_set_strict_mode;
>>   } LIBBPF_0.4.0;
>> +
>> +LIBBPF_0.6.0 {
>> +       global:
>> +               btf__add_tag;
>> +} LIBBPF_0.5.0;
> 
> you'll need a rebase for this due to my patch for libbpf_version.h, sorry
> 
>> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
>> index 4f6ff5c23695..ceb0c98979bc 100644
>> --- a/tools/lib/bpf/libbpf_internal.h
>> +++ b/tools/lib/bpf/libbpf_internal.h
>> @@ -69,6 +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)
>>
>>   #ifndef likely
>>   #define likely(x) __builtin_expect(!!(x), 1)
>> --
>> 2.30.2
>>
diff mbox series

Patch

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 7cb6ebf1be37..f4dc3741af47 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -304,6 +304,8 @@  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);
 	default:
 		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
 		return -EINVAL;
@@ -376,6 +378,9 @@  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);
+		return 0;
 	default:
 		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
 		return -EINVAL;
@@ -586,6 +591,7 @@  __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:
 			type_id = t->type;
 			break;
 		case BTF_KIND_ARRAY:
@@ -2440,6 +2446,49 @@  int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
 	return 0;
 }
 
+/*
+ * Append new BTF_KIND_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
+ *     member or function argument index;
+ * Returns:
+ *   - >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 component_idx)
+{
+	bool for_ref_type = false;
+	struct btf_type *t;
+	int sz, value_off;
+
+	if (!value || !value[0] || component_idx < -1)
+		return libbpf_err(-EINVAL);
+
+	if (validate_type_id(ref_type_id))
+		return libbpf_err(-EINVAL);
+
+	if (btf_ensure_modifiable(btf))
+		return libbpf_err(-ENOMEM);
+
+	sz = sizeof(struct btf_type) + sizeof(struct btf_tag);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return libbpf_err(-ENOMEM);
+
+	value_off = btf__add_str(btf, value);
+	if (value_off < 0)
+		return value_off;
+
+	t->name_off = value_off;
+	t->info = btf_type_info(BTF_KIND_TAG, 0, for_ref_type);
+	t->type = ref_type_id;
+	((struct btf_tag *)(t + 1))->component_idx = component_idx;
+
+	return btf_commit_type(btf, sz);
+}
+
 struct btf_ext_sec_setup_param {
 	__u32 off;
 	__u32 len;
@@ -3535,6 +3584,7 @@  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);
 			break;
 		case BTF_KIND_ENUM:
@@ -3590,6 +3640,7 @@  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:
 		return 0;
 
 	case BTF_KIND_INT:
@@ -4210,6 +4261,23 @@  static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 		}
 		break;
 
+	case BTF_KIND_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);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_int_tag(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
 	case BTF_KIND_ARRAY: {
 		struct btf_array *info = btf_array(t);
 
@@ -4482,6 +4550,7 @@  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:
 		return visit(&t->type, ctx);
 
 	case BTF_KIND_ARRAY: {
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index f2e2fab950b7..659ea8a2769b 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -143,6 +143,10 @@  LIBBPF_API int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz
 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,
+			    int component_idx);
+
 struct btf_dedup_opts {
 	unsigned int dedup_table_size;
 	bool dont_resolve_fwds;
@@ -330,6 +334,11 @@  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)
+{
+	return btf_kind(t) == BTF_KIND_TAG;
+}
+
 static inline __u8 btf_int_encoding(const struct btf_type *t)
 {
 	return BTF_INT_ENCODING(*(__u32 *)(t + 1));
@@ -398,6 +407,12 @@  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)
+{
+	return (struct btf_tag *)(t + 1);
+}
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index e4b483f15fb9..ad6df97295ae 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -316,6 +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:
 			d->type_states[t->type].referenced = 1;
 			break;
 
@@ -583,6 +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:
 		d->type_states[id].order_state = ORDERED;
 		return 0;
 
@@ -2215,6 +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:
 		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 8f579c6666b2..4a62ef714562 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -195,6 +195,8 @@  enum kern_feature_id {
 	FEAT_BTF_FLOAT,
 	/* BPF perf link support */
 	FEAT_PERF_LINK,
+	/* BTF_KIND_ATTR support */
+	FEAT_BTF_TAG,
 	__FEAT_CNT,
 };
 
@@ -1987,6 +1989,7 @@  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";
 	default: return "unknown";
 	}
 }
@@ -2486,8 +2489,9 @@  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);
 
-	return !has_func || !has_datasec || !has_func_global || !has_float;
+	return !has_func || !has_datasec || !has_func_global || !has_float || !has_tag;
 }
 
 static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@@ -2496,14 +2500,15 @@  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);
 	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)) {
-			/* replace VAR with INT */
+		if ((!has_datasec && btf_is_var(t)) || (!has_tag && btf_is_tag(t))) {
+			/* replace VAR/TAG with INT */
 			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
 			/*
 			 * using size = 1 is the safest choice, 4 will be too
@@ -4213,6 +4218,23 @@  static int probe_kern_btf_float(void)
 					     strs, sizeof(strs)));
 }
 
+static int probe_kern_btf_tag(void)
+{
+	static const char strs[] = "\0tag";
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* VAR x */                                     /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+		BTF_VAR_STATIC,
+		/* attr */
+		BTF_TYPE_TAG_ENC(1, 2, -1),
+	};
+
+	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+					     strs, sizeof(strs)));
+}
+
 static int probe_kern_array_mmap(void)
 {
 	struct bpf_create_map_attr attr = {
@@ -4429,6 +4451,9 @@  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,
+	},
 };
 
 static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index bbc53bb25f68..9e649cf9e771 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -386,3 +386,8 @@  LIBBPF_0.5.0 {
 		btf_dump__dump_type_data;
 		libbpf_set_strict_mode;
 } LIBBPF_0.4.0;
+
+LIBBPF_0.6.0 {
+	global:
+		btf__add_tag;
+} LIBBPF_0.5.0;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 4f6ff5c23695..ceb0c98979bc 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -69,6 +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)
 
 #ifndef likely
 #define likely(x) __builtin_expect(!!(x), 1)