diff mbox series

[v3,bpf-next,2/6] libbpf: Add BTF_KIND_FLOAT support

Message ID 20210220034959.27006-3-iii@linux.ibm.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Add BTF_KIND_FLOAT support | expand

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Commit Message

Ilya Leoshkevich Feb. 20, 2021, 3:49 a.m. UTC 
The logic follows that of BTF_KIND_INT most of the time. Sanitization
replaces BTF_KIND_FLOATs with BTF_KIND_CONSTs pointing to
equally-sized BTF_KIND_ARRAYs on older kernels.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 tools/lib/bpf/btf.c             | 44 ++++++++++++++++++++++++++++++
 tools/lib/bpf/btf.h             |  8 ++++++
 tools/lib/bpf/btf_dump.c        |  4 +++
 tools/lib/bpf/libbpf.c          | 48 ++++++++++++++++++++++++++++++++-
 tools/lib/bpf/libbpf.map        |  5 ++++
 tools/lib/bpf/libbpf_internal.h |  2 ++
 6 files changed, 110 insertions(+), 1 deletion(-)

Comments

Yonghong Song Feb. 22, 2021, 3:41 a.m. UTC | #1 
On 2/19/21 7:49 PM, Ilya Leoshkevich wrote:
> The logic follows that of BTF_KIND_INT most of the time. Sanitization
> replaces BTF_KIND_FLOATs with BTF_KIND_CONSTs pointing to
> equally-sized BTF_KIND_ARRAYs on older kernels.
> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>   tools/lib/bpf/btf.c             | 44 ++++++++++++++++++++++++++++++
>   tools/lib/bpf/btf.h             |  8 ++++++
>   tools/lib/bpf/btf_dump.c        |  4 +++
>   tools/lib/bpf/libbpf.c          | 48 ++++++++++++++++++++++++++++++++-
>   tools/lib/bpf/libbpf.map        |  5 ++++
>   tools/lib/bpf/libbpf_internal.h |  2 ++
>   6 files changed, 110 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index fdfff544f59a..1ebfcc687dab 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -292,6 +292,7 @@ static int btf_type_size(const struct btf_type *t)
>   	case BTF_KIND_PTR:
>   	case BTF_KIND_TYPEDEF:
>   	case BTF_KIND_FUNC:
> +	case BTF_KIND_FLOAT:
>   		return base_size;
>   	case BTF_KIND_INT:
>   		return base_size + sizeof(__u32);
> @@ -339,6 +340,7 @@ static int btf_bswap_type_rest(struct btf_type *t)
>   	case BTF_KIND_PTR:
>   	case BTF_KIND_TYPEDEF:
>   	case BTF_KIND_FUNC:
> +	case BTF_KIND_FLOAT:
>   		return 0;
>   	case BTF_KIND_INT:
>   		*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
> @@ -579,6 +581,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
>   		case BTF_KIND_UNION:
>   		case BTF_KIND_ENUM:
>   		case BTF_KIND_DATASEC:
> +		case BTF_KIND_FLOAT:
>   			size = t->size;
>   			goto done;
>   		case BTF_KIND_PTR:
> @@ -622,6 +625,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
>   	switch (kind) {
>   	case BTF_KIND_INT:
>   	case BTF_KIND_ENUM:
> +	case BTF_KIND_FLOAT:
>   		return min(btf_ptr_sz(btf), (size_t)t->size);
>   	case BTF_KIND_PTR:
>   		return btf_ptr_sz(btf);
> @@ -2400,6 +2404,42 @@ int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
>   	return btf_commit_type(btf, sz);
>   }
[...]

I skipped deduplication part, Andrii can take a look later.

> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index d43cc3f29dae..b79a6a2e6faa 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -178,6 +178,8 @@ enum kern_feature_id {
>   	FEAT_PROG_BIND_MAP,
>   	/* Kernel support for module BTFs */
>   	FEAT_MODULE_BTF,
> +	/* BTF_KIND_FLOAT support */
> +	FEAT_BTF_FLOAT,
>   	__FEAT_CNT,
>   };
>   
> @@ -1935,6 +1937,7 @@ static const char *btf_kind_str(const struct btf_type *t)
>   	case BTF_KIND_FUNC_PROTO: return "func_proto";
>   	case BTF_KIND_VAR: return "var";
>   	case BTF_KIND_DATASEC: return "datasec";
> +	case BTF_KIND_FLOAT: return "float";
>   	default: return "unknown";
>   	}
>   }
> @@ -2384,18 +2387,22 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
>   {
>   	bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
>   	bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
> +	bool has_float = kernel_supports(FEAT_BTF_FLOAT);
>   	bool has_func = kernel_supports(FEAT_BTF_FUNC);
>   
> -	return !has_func || !has_datasec || !has_func_global;
> +	return !has_func || !has_datasec || !has_func_global || !has_float;
>   }
>   
>   static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
>   {
>   	bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
>   	bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
> +	bool has_float = kernel_supports(FEAT_BTF_FLOAT);
>   	bool has_func = kernel_supports(FEAT_BTF_FUNC);
>   	struct btf_type *t;
> +	int t_uchar = 0;
>   	int i, j, vlen;
> +	int t_uint = 0;
>   
>   	for (i = 1; i <= btf__get_nr_types(btf); i++) {
>   		t = (struct btf_type *)btf__type_by_id(btf, i);
> @@ -2445,6 +2452,26 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
>   		} else if (!has_func_global && btf_is_func(t)) {
>   			/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
>   			t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
> +		} else if (!has_float && btf_is_float(t)) {
> +			/* replace FLOAT with TYPEDEF(u8[]) */

replace FLOAT with CONST(u8[]).

> +			int t_array;
> +			__u32 size;
> +
> +			size = t->size;
> +			if (!t_uchar)
> +				t_uchar = btf__add_int(btf, "unsigned char", 1,
> +						       0);
> +			if (!t_uint)
> +				t_uint = btf__add_int(btf, "unsigned int", 4,
> +						      0);
> +			t_array = btf__add_array(btf, t_uint, t_uchar, size);

Checking whether t_array is valid here or not?
We do not need to check t_uchar/t_uint. If they are invalid 
btf__add_array() will return -EINVAL.

> +
> +			/* adding new types may have invalidated t */
> +			t = (struct btf_type *)btf__type_by_id(btf, i);
> +
> +			t->name_off = 0;
> +			t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
> +			t->type = t_array;
>   		}
>   	}
>   }
> @@ -3882,6 +3909,18 @@ static int probe_kern_btf_datasec(void)
>   					     strs, sizeof(strs)));
>   }
>   
> +static int probe_kern_btf_float(void)
> +{
> +	static const char strs[] = "\0float";
> +	__u32 types[] = {
> +		/* float */
> +		BTF_TYPE_FLOAT_ENC(1, 4),
> +	};
> +
> +	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 = {
> @@ -4061,6 +4100,9 @@ static struct kern_feature_desc {
>   	[FEAT_MODULE_BTF] = {
>   		"module BTF support", probe_module_btf,
>   	},
> +	[FEAT_BTF_FLOAT] = {
> +		"BTF_KIND_FLOAT support", probe_kern_btf_float,
> +	},
>   };
>   
>   static bool kernel_supports(enum kern_feature_id feat_id)
> @@ -4940,6 +4982,8 @@ static int bpf_core_fields_are_compat(const struct btf *local_btf,
>   		local_id = btf_array(local_type)->type;
>   		targ_id = btf_array(targ_type)->type;
>   		goto recur;
> +	case BTF_KIND_FLOAT:
> +		return local_type->size == targ_type->size;
>   	default:
>   		pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
>   			btf_kind(local_type), local_id, targ_id);
> @@ -5122,6 +5166,8 @@ static int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id
>   		skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id);
>   		goto recur;
>   	}
> +	case BTF_KIND_FLOAT:
> +		return local_type->size == targ_type->size;
>   	default:
>   		pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
>   			btf_kind_str(local_type), local_id, targ_id);
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 1c0fd2dd233a..ec898f464ab9 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -350,3 +350,8 @@ LIBBPF_0.3.0 {
>   		xsk_setup_xdp_prog;
>   		xsk_socket__update_xskmap;
>   } LIBBPF_0.2.0;
> +
> +LIBBPF_0.4.0 {
> +	global:
> +		btf__add_float;
> +} LIBBPF_0.3.0;
> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> index 969d0ac592ba..343f6eb05637 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -31,6 +31,8 @@
>   #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
>   #define BTF_PARAM_ENC(name, type) (name), (type)
>   #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)
>   
>   #ifndef likely
>   #define likely(x) __builtin_expect(!!(x), 1)
>
diff mbox series

Patch

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index fdfff544f59a..1ebfcc687dab 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -292,6 +292,7 @@  static int btf_type_size(const struct btf_type *t)
 	case BTF_KIND_PTR:
 	case BTF_KIND_TYPEDEF:
 	case BTF_KIND_FUNC:
+	case BTF_KIND_FLOAT:
 		return base_size;
 	case BTF_KIND_INT:
 		return base_size + sizeof(__u32);
@@ -339,6 +340,7 @@  static int btf_bswap_type_rest(struct btf_type *t)
 	case BTF_KIND_PTR:
 	case BTF_KIND_TYPEDEF:
 	case BTF_KIND_FUNC:
+	case BTF_KIND_FLOAT:
 		return 0;
 	case BTF_KIND_INT:
 		*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
@@ -579,6 +581,7 @@  __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 		case BTF_KIND_UNION:
 		case BTF_KIND_ENUM:
 		case BTF_KIND_DATASEC:
+		case BTF_KIND_FLOAT:
 			size = t->size;
 			goto done;
 		case BTF_KIND_PTR:
@@ -622,6 +625,7 @@  int btf__align_of(const struct btf *btf, __u32 id)
 	switch (kind) {
 	case BTF_KIND_INT:
 	case BTF_KIND_ENUM:
+	case BTF_KIND_FLOAT:
 		return min(btf_ptr_sz(btf), (size_t)t->size);
 	case BTF_KIND_PTR:
 		return btf_ptr_sz(btf);
@@ -2400,6 +2404,42 @@  int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
 	return btf_commit_type(btf, sz);
 }
 
+/*
+ * Append new BTF_KIND_FLOAT type with:
+ *   - *name* - non-empty, non-NULL type name;
+ *   - *sz* - size of the type, in bytes;
+ * Returns:
+ *   - >0, type ID of newly added BTF type;
+ *   - <0, on error.
+ */
+int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
+{
+	struct btf_type *t;
+	int sz, name_off;
+
+	/* non-empty name */
+	if (!name || !name[0])
+		return -EINVAL;
+
+	if (btf_ensure_modifiable(btf))
+		return -ENOMEM;
+
+	sz = sizeof(struct btf_type);
+	t = btf_add_type_mem(btf, sz);
+	if (!t)
+		return -ENOMEM;
+
+	name_off = btf__add_str(btf, name);
+	if (name_off < 0)
+		return name_off;
+
+	t->name_off = name_off;
+	t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
+	t->size = byte_sz;
+
+	return btf_commit_type(btf, sz);
+}
+
 /*
  * Append new data section variable information entry for current DATASEC type:
  *   - *var_type_id* - type ID, describing type of the variable;
@@ -3653,6 +3693,7 @@  static int btf_dedup_prep(struct btf_dedup *d)
 		case BTF_KIND_FWD:
 		case BTF_KIND_TYPEDEF:
 		case BTF_KIND_FUNC:
+		case BTF_KIND_FLOAT:
 			h = btf_hash_common(t);
 			break;
 		case BTF_KIND_INT:
@@ -3749,6 +3790,7 @@  static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
 		break;
 
 	case BTF_KIND_FWD:
+	case BTF_KIND_FLOAT:
 		h = btf_hash_common(t);
 		for_each_dedup_cand(d, hash_entry, h) {
 			cand_id = (__u32)(long)hash_entry->value;
@@ -4010,6 +4052,7 @@  static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 			return btf_compat_enum(cand_type, canon_type);
 
 	case BTF_KIND_FWD:
+	case BTF_KIND_FLOAT:
 		return btf_equal_common(cand_type, canon_type);
 
 	case BTF_KIND_CONST:
@@ -4506,6 +4549,7 @@  static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 	switch (btf_kind(t)) {
 	case BTF_KIND_INT:
 	case BTF_KIND_ENUM:
+	case BTF_KIND_FLOAT:
 		break;
 
 	case BTF_KIND_FWD:
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 1237bcd1dd17..c3b11bcebeda 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -132,6 +132,9 @@  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);
 
+/* float construction APIs */
+LIBBPF_API int btf__add_float(struct btf *btf, const char *name, size_t byte_sz);
+
 struct btf_dedup_opts {
 	unsigned int dedup_table_size;
 	bool dont_resolve_fwds;
@@ -294,6 +297,11 @@  static inline bool btf_is_datasec(const struct btf_type *t)
 	return btf_kind(t) == BTF_KIND_DATASEC;
 }
 
+static inline bool btf_is_float(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FLOAT;
+}
+
 static inline __u8 btf_int_encoding(const struct btf_type *t)
 {
 	return BTF_INT_ENCODING(*(__u32 *)(t + 1));
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 2f9d685bd522..5e957fcceee6 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -279,6 +279,7 @@  static int btf_dump_mark_referenced(struct btf_dump *d)
 		case BTF_KIND_INT:
 		case BTF_KIND_ENUM:
 		case BTF_KIND_FWD:
+		case BTF_KIND_FLOAT:
 			break;
 
 		case BTF_KIND_VOLATILE:
@@ -453,6 +454,7 @@  static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
 
 	switch (btf_kind(t)) {
 	case BTF_KIND_INT:
+	case BTF_KIND_FLOAT:
 		tstate->order_state = ORDERED;
 		return 0;
 
@@ -1133,6 +1135,7 @@  static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
 		case BTF_KIND_STRUCT:
 		case BTF_KIND_UNION:
 		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_FLOAT:
 			goto done;
 		default:
 			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
@@ -1247,6 +1250,7 @@  static void btf_dump_emit_type_chain(struct btf_dump *d,
 
 		switch (kind) {
 		case BTF_KIND_INT:
+		case BTF_KIND_FLOAT:
 			btf_dump_emit_mods(d, decls);
 			name = btf_name_of(d, t->name_off);
 			btf_dump_printf(d, "%s", name);
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index d43cc3f29dae..b79a6a2e6faa 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -178,6 +178,8 @@  enum kern_feature_id {
 	FEAT_PROG_BIND_MAP,
 	/* Kernel support for module BTFs */
 	FEAT_MODULE_BTF,
+	/* BTF_KIND_FLOAT support */
+	FEAT_BTF_FLOAT,
 	__FEAT_CNT,
 };
 
@@ -1935,6 +1937,7 @@  static const char *btf_kind_str(const struct btf_type *t)
 	case BTF_KIND_FUNC_PROTO: return "func_proto";
 	case BTF_KIND_VAR: return "var";
 	case BTF_KIND_DATASEC: return "datasec";
+	case BTF_KIND_FLOAT: return "float";
 	default: return "unknown";
 	}
 }
@@ -2384,18 +2387,22 @@  static bool btf_needs_sanitization(struct bpf_object *obj)
 {
 	bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
 	bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
+	bool has_float = kernel_supports(FEAT_BTF_FLOAT);
 	bool has_func = kernel_supports(FEAT_BTF_FUNC);
 
-	return !has_func || !has_datasec || !has_func_global;
+	return !has_func || !has_datasec || !has_func_global || !has_float;
 }
 
 static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
 {
 	bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
 	bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
+	bool has_float = kernel_supports(FEAT_BTF_FLOAT);
 	bool has_func = kernel_supports(FEAT_BTF_FUNC);
 	struct btf_type *t;
+	int t_uchar = 0;
 	int i, j, vlen;
+	int t_uint = 0;
 
 	for (i = 1; i <= btf__get_nr_types(btf); i++) {
 		t = (struct btf_type *)btf__type_by_id(btf, i);
@@ -2445,6 +2452,26 @@  static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
 		} else if (!has_func_global && btf_is_func(t)) {
 			/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
 			t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
+		} else if (!has_float && btf_is_float(t)) {
+			/* replace FLOAT with TYPEDEF(u8[]) */
+			int t_array;
+			__u32 size;
+
+			size = t->size;
+			if (!t_uchar)
+				t_uchar = btf__add_int(btf, "unsigned char", 1,
+						       0);
+			if (!t_uint)
+				t_uint = btf__add_int(btf, "unsigned int", 4,
+						      0);
+			t_array = btf__add_array(btf, t_uint, t_uchar, size);
+
+			/* adding new types may have invalidated t */
+			t = (struct btf_type *)btf__type_by_id(btf, i);
+
+			t->name_off = 0;
+			t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
+			t->type = t_array;
 		}
 	}
 }
@@ -3882,6 +3909,18 @@  static int probe_kern_btf_datasec(void)
 					     strs, sizeof(strs)));
 }
 
+static int probe_kern_btf_float(void)
+{
+	static const char strs[] = "\0float";
+	__u32 types[] = {
+		/* float */
+		BTF_TYPE_FLOAT_ENC(1, 4),
+	};
+
+	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 = {
@@ -4061,6 +4100,9 @@  static struct kern_feature_desc {
 	[FEAT_MODULE_BTF] = {
 		"module BTF support", probe_module_btf,
 	},
+	[FEAT_BTF_FLOAT] = {
+		"BTF_KIND_FLOAT support", probe_kern_btf_float,
+	},
 };
 
 static bool kernel_supports(enum kern_feature_id feat_id)
@@ -4940,6 +4982,8 @@  static int bpf_core_fields_are_compat(const struct btf *local_btf,
 		local_id = btf_array(local_type)->type;
 		targ_id = btf_array(targ_type)->type;
 		goto recur;
+	case BTF_KIND_FLOAT:
+		return local_type->size == targ_type->size;
 	default:
 		pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
 			btf_kind(local_type), local_id, targ_id);
@@ -5122,6 +5166,8 @@  static int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id
 		skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id);
 		goto recur;
 	}
+	case BTF_KIND_FLOAT:
+		return local_type->size == targ_type->size;
 	default:
 		pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
 			btf_kind_str(local_type), local_id, targ_id);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 1c0fd2dd233a..ec898f464ab9 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -350,3 +350,8 @@  LIBBPF_0.3.0 {
 		xsk_setup_xdp_prog;
 		xsk_socket__update_xskmap;
 } LIBBPF_0.2.0;
+
+LIBBPF_0.4.0 {
+	global:
+		btf__add_float;
+} LIBBPF_0.3.0;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 969d0ac592ba..343f6eb05637 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -31,6 +31,8 @@ 
 #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
 #define BTF_PARAM_ENC(name, type) (name), (type)
 #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)
 
 #ifndef likely
 #define likely(x) __builtin_expect(!!(x), 1)