!108 tools/bpftool: Add BTF_KIND_FLOAT support

Merge Pull Request from: @zhengzengkai 
 
Some BPF programs compiled on s390 fail to load, because s390
arch-specific linux headers contain float and double types.

Introduce support for such types by representing them using the new
BTF_KIND_FLOAT. This series deals with libbpf, bpftool, in-kernel BTF
parser as well as selftests and documentation. 
 
Link:https://gitee.com/openeuler/kernel/pulls/108 
Reviewed-by: Xu Kuohai <xukuohai@huawei.com> 
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com> 

Documentation/bpf/btf.rst

@@ -84,6 +84,7 @@ sequentially and type id is assigned to each recognized type starting from id
     #define BTF_KIND_FUNC_PROTO     13      /* Function Proto       */
     #define BTF_KIND_VAR            14      /* Variable     */
     #define BTF_KIND_DATASEC        15      /* Section      */
+    #define BTF_KIND_FLOAT          16      /* Floating point       */
     #define BTF_KIND_DECL_TAG       17      /* Decl Tag     */
     #define BTF_KIND_TYPE_TAG       18      /* Type Tag     */
 
@@ -97,8 +98,8 @@ Each type contains the following common data::
         /* "info" bits arrangement
          * bits  0-15: vlen (e.g. # of struct's members)
          * bits 16-23: unused
-         * bits 24-27: kind (e.g. int, ptr, array...etc)
-         * bits 28-30: unused
+         * bits 24-28: kind (e.g. int, ptr, array...etc)
+         * bits 29-30: unused
          * bit     31: kind_flag, currently used by
          *             struct, union and fwd
          */
@@ -454,6 +455,18 @@ map definition.
   * ``offset``: the in-section offset of the variable
   * ``size``: the size of the variable in bytes
 
+2.2.16 BTF_KIND_FLOAT
+~~~~~~~~~~~~~~~~~~~~~
+
+``struct btf_type`` encoding requirement:
+ * ``name_off``: any valid offset
+ * ``info.kind_flag``: 0
+ * ``info.kind``: BTF_KIND_FLOAT
+ * ``info.vlen``: 0
+ * ``size``: the size of the float type in bytes: 2, 4, 8, 12 or 16.
+
+No additional type data follow ``btf_type``.
+
 2.2.17 BTF_KIND_DECL_TAG
 ~~~~~~~~~~~~~~~~~~~~~~~~
 

kernel/bpf/btf.c

@@ -174,7 +174,7 @@
 #define BITS_ROUNDUP_BYTES(bits) \
 	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
 
-#define BTF_INFO_MASK 0x8f00ffff
+#define BTF_INFO_MASK 0x9f00ffff
 #define BTF_INT_MASK 0x0fffffff
 #define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
 #define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
@@ -281,6 +281,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
 	[BTF_KIND_FUNC_PROTO]	= "FUNC_PROTO",
 	[BTF_KIND_VAR]		= "VAR",
 	[BTF_KIND_DATASEC]	= "DATASEC",
+	[BTF_KIND_FLOAT]	= "FLOAT",
 	[BTF_KIND_DECL_TAG]	= "DECL_TAG",
 	[BTF_KIND_TYPE_TAG]	= "TYPE_TAG",
 };
@@ -591,6 +592,7 @@ static bool btf_type_has_size(const struct btf_type *t)
 	case BTF_KIND_UNION:
 	case BTF_KIND_ENUM:
 	case BTF_KIND_DATASEC:
+	case BTF_KIND_FLOAT:
 		return true;
 	}
 
@@ -1726,6 +1728,7 @@ __btf_resolve_size(const struct btf *btf, const struct btf_type *type,
 		case BTF_KIND_STRUCT:
 		case BTF_KIND_UNION:
 		case BTF_KIND_ENUM:
+		case BTF_KIND_FLOAT:
 			size = type->size;
 			goto resolved;
 
@@ -1872,7 +1875,7 @@ static int btf_df_check_kflag_member(struct btf_verifier_env *env,
 	return -EINVAL;
 }
 
-/* Used for ptr, array and struct/union type members.
+/* Used for ptr, array struct/union and float type members.
  * int, enum and modifier types have their specific callback functions.
  */
 static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
@@ -3706,6 +3709,81 @@ static const struct btf_kind_operations datasec_ops = {
 	.show			= btf_datasec_show,
 };
 
+static s32 btf_float_check_meta(struct btf_verifier_env *env,
+				const struct btf_type *t,
+				u32 meta_left)
+{
+	if (btf_type_vlen(t)) {
+		btf_verifier_log_type(env, t, "vlen != 0");
+		return -EINVAL;
+	}
+
+	if (btf_type_kflag(t)) {
+		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
+		return -EINVAL;
+	}
+
+	if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&
+	    t->size != 16) {
+		btf_verifier_log_type(env, t, "Invalid type_size");
+		return -EINVAL;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	return 0;
+}
+
+static int btf_float_check_member(struct btf_verifier_env *env,
+				  const struct btf_type *struct_type,
+				  const struct btf_member *member,
+				  const struct btf_type *member_type)
+{
+	u64 start_offset_bytes;
+	u64 end_offset_bytes;
+	u64 misalign_bits;
+	u64 align_bytes;
+	u64 align_bits;
+
+	/* Different architectures have different alignment requirements, so
+	 * here we check only for the reasonable minimum. This way we ensure
+	 * that types after CO-RE can pass the kernel BTF verifier.
+	 */
+	align_bytes = min_t(u64, sizeof(void *), member_type->size);
+	align_bits = align_bytes * BITS_PER_BYTE;
+	div64_u64_rem(member->offset, align_bits, &misalign_bits);
+	if (misalign_bits) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member is not properly aligned");
+		return -EINVAL;
+	}
+
+	start_offset_bytes = member->offset / BITS_PER_BYTE;
+	end_offset_bytes = start_offset_bytes + member_type->size;
+	if (end_offset_bytes > struct_type->size) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member exceeds struct_size");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void btf_float_log(struct btf_verifier_env *env,
+			  const struct btf_type *t)
+{
+	btf_verifier_log(env, "size=%u", t->size);
+}
+
+static const struct btf_kind_operations float_ops = {
+	.check_meta = btf_float_check_meta,
+	.resolve = btf_df_resolve,
+	.check_member = btf_float_check_member,
+	.check_kflag_member = btf_generic_check_kflag_member,
+	.log_details = btf_float_log,
+	.show = btf_df_show,
+};
+	
 static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
 			      const struct btf_type *t,
 			      u32 meta_left)
@@ -3943,6 +4021,7 @@ static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
 	[BTF_KIND_FUNC_PROTO] = &func_proto_ops,
 	[BTF_KIND_VAR] = &var_ops,
 	[BTF_KIND_DATASEC] = &datasec_ops,
+	[BTF_KIND_FLOAT] = &float_ops,
 	[BTF_KIND_DECL_TAG] = &decl_tag_ops,
 	[BTF_KIND_TYPE_TAG] = &modifier_ops,
 };

tools/bpf/bpftool/btf.c

@@ -36,6 +36,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
 	[BTF_KIND_FUNC_PROTO]	= "FUNC_PROTO",
 	[BTF_KIND_VAR]		= "VAR",
 	[BTF_KIND_DATASEC]	= "DATASEC",
+	[BTF_KIND_FLOAT]	= "FLOAT",
 	[BTF_KIND_DECL_TAG]	= "DECL_TAG",
 	[BTF_KIND_TYPE_TAG]	= "TYPE_TAG",
 };
@@ -330,6 +331,13 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 			jsonw_end_array(w);
 		break;
 	}
+	case BTF_KIND_FLOAT: {
+		if (json_output)
+			jsonw_uint_field(w, "size", t->size);
+		else
+			printf(" size=%u", t->size);
+		break;
+	}
 	case BTF_KIND_DECL_TAG: {
 		const struct btf_decl_tag *tag = (const void *)(t + 1);
 

tools/bpf/bpftool/btf_dumper.c

@@ -598,6 +598,7 @@ static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
 	switch (BTF_INFO_KIND(t->info)) {
 	case BTF_KIND_INT:
 	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FLOAT:
 		BTF_PRINT_ARG("%s ", btf__name_by_offset(btf, t->name_off));
 		break;
 	case BTF_KIND_STRUCT:

tools/testing/selftests/bpf/btf_helpers.c

@@ -23,6 +23,7 @@ static const char * const btf_kind_str_mapping[] = {
 	[BTF_KIND_FUNC_PROTO]	= "FUNC_PROTO",
 	[BTF_KIND_VAR]		= "VAR",
 	[BTF_KIND_DATASEC]	= "DATASEC",
+	[BTF_KIND_FLOAT]	= "FLOAT",
 };
 
 static const char *btf_kind_str(__u16 kind)
@@ -173,6 +174,9 @@ int fprintf_btf_type_raw(FILE *out, const struct btf *btf, __u32 id)
 		}
 		break;
 	}
+	case BTF_KIND_FLOAT:
+		fprintf(out, " size=%u", t->size);
+		break;
 	default:
 		break;
 	}

tools/testing/selftests/bpf/prog_tests/btf.c

@@ -1903,7 +1903,7 @@ static struct btf_raw_test raw_tests[] = {
 	.raw_types = {
 		/* int */				/* [1] */
 		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
-		BTF_TYPE_ENC(0, 0x10000000, 4),
+		BTF_TYPE_ENC(0, 0x20000000, 4),
 		BTF_END_RAW,
 	},
 	.str_sec = "",
@@ -3531,6 +3531,136 @@ static struct btf_raw_test raw_tests[] = {
 	.max_entries = 1,
 },
 
+{
+	.descr = "float test #1, well-formed",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+								/* [1] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 2),		/* [2] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 4),		/* [3] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 8),		/* [4] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 12),		/* [5] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 16),		/* [6] */
+		BTF_STRUCT_ENC(NAME_TBD, 5, 48),		/* [7] */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 0),
+		BTF_MEMBER_ENC(NAME_TBD, 3, 32),
+		BTF_MEMBER_ENC(NAME_TBD, 4, 64),
+		BTF_MEMBER_ENC(NAME_TBD, 5, 128),
+		BTF_MEMBER_ENC(NAME_TBD, 6, 256),
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0int\0_Float16\0float\0double\0_Float80\0long_double"
+		    "\0floats\0a\0b\0c\0d\0e"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "float_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 48,
+	.key_type_id = 1,
+	.value_type_id = 7,
+	.max_entries = 1,
+},
+{
+	.descr = "float test #2, invalid vlen",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+								/* [1] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 1), 4),
+								/* [2] */
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0int\0float"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "float_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 4,
+	.key_type_id = 1,
+	.value_type_id = 2,
+	.max_entries = 1,
+	.btf_load_err = true,
+	.err_str = "vlen != 0",
+},
+{
+	.descr = "float test #3, invalid kind_flag",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+								/* [1] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_FLOAT, 1, 0), 4),
+								/* [2] */
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0int\0float"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "float_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 4,
+	.key_type_id = 1,
+	.value_type_id = 2,
+	.max_entries = 1,
+	.btf_load_err = true,
+	.err_str = "Invalid btf_info kind_flag",
+},
+{
+	.descr = "float test #4, member does not fit",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+								/* [1] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 4),		/* [2] */
+		BTF_STRUCT_ENC(NAME_TBD, 1, 2),			/* [3] */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 0),
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0int\0float\0floats\0x"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "float_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 4,
+	.key_type_id = 1,
+	.value_type_id = 3,
+	.max_entries = 1,
+	.btf_load_err = true,
+	.err_str = "Member exceeds struct_size",
+},
+{
+	.descr = "float test #5, member is not properly aligned",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+								/* [1] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 4),		/* [2] */
+		BTF_STRUCT_ENC(NAME_TBD, 1, 8),			/* [3] */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 8),
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0int\0float\0floats\0x"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "float_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 4,
+	.key_type_id = 1,
+	.value_type_id = 3,
+	.max_entries = 1,
+	.btf_load_err = true,
+	.err_str = "Member is not properly aligned",
+},
+{
+	.descr = "float test #6, invalid size",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+								/* [1] */
+		BTF_TYPE_FLOAT_ENC(NAME_TBD, 6),		/* [2] */
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0int\0float"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "float_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 6,
+	.key_type_id = 1,
+	.value_type_id = 2,
+	.max_entries = 1,
+	.btf_load_err = true,
+	.err_str = "Invalid type_size",
+},
+
 }; /* struct btf_raw_test raw_tests[] */
 
 static const char *get_next_str(const char *start, const char *end)
@@ -6284,11 +6414,12 @@ const struct btf_dedup_test dedup_tests[] = {
 			/* int[16] */
 			BTF_TYPE_ARRAY_ENC(1, 1, 16),					/* [2] */
 			/* struct s { */
-			BTF_STRUCT_ENC(NAME_NTH(2), 4, 84),				/* [3] */
+			BTF_STRUCT_ENC(NAME_NTH(2), 5, 88),				/* [3] */
 				BTF_MEMBER_ENC(NAME_NTH(3), 4, 0),	/* struct s *next;	*/
 				BTF_MEMBER_ENC(NAME_NTH(4), 5, 64),	/* const int *a;	*/
 				BTF_MEMBER_ENC(NAME_NTH(5), 2, 128),	/* int b[16];		*/
 				BTF_MEMBER_ENC(NAME_NTH(6), 1, 640),	/* int c;		*/
+				BTF_MEMBER_ENC(NAME_NTH(8), 13, 672),	/* float d;		*/
 			/* ptr -> [3] struct s */
 			BTF_PTR_ENC(3),							/* [4] */
 			/* ptr -> [6] const int */
@@ -6299,39 +6430,43 @@ const struct btf_dedup_test dedup_tests[] = {
 			/* full copy of the above */
 			BTF_TYPE_INT_ENC(NAME_NTH(1), BTF_INT_SIGNED, 0, 32, 4),	/* [7] */
 			BTF_TYPE_ARRAY_ENC(7, 7, 16),					/* [8] */
-			BTF_STRUCT_ENC(NAME_NTH(2), 4, 84),				/* [9] */
+			BTF_STRUCT_ENC(NAME_NTH(2), 5, 88),				/* [9] */
 				BTF_MEMBER_ENC(NAME_NTH(3), 10, 0),
 				BTF_MEMBER_ENC(NAME_NTH(4), 11, 64),
 				BTF_MEMBER_ENC(NAME_NTH(5), 8, 128),
 				BTF_MEMBER_ENC(NAME_NTH(6), 7, 640),
+				BTF_MEMBER_ENC(NAME_NTH(8), 13, 672),
 			BTF_PTR_ENC(9),							/* [10] */
 			BTF_PTR_ENC(12),						/* [11] */
 			BTF_CONST_ENC(7),						/* [12] */
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(7), 4),				/* [13] */
 			BTF_END_RAW,
 		},
-		BTF_STR_SEC("\0int\0s\0next\0a\0b\0c\0"),
+		BTF_STR_SEC("\0int\0s\0next\0a\0b\0c\0float\0d"),
 	},
 	.expect = {
 		.raw_types = {
 			/* int */
-			BTF_TYPE_INT_ENC(NAME_NTH(4), BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+			BTF_TYPE_INT_ENC(NAME_NTH(5), BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
 			/* int[16] */
 			BTF_TYPE_ARRAY_ENC(1, 1, 16),					/* [2] */
 			/* struct s { */
-			BTF_STRUCT_ENC(NAME_NTH(6), 4, 84),				/* [3] */
-				BTF_MEMBER_ENC(NAME_NTH(5), 4, 0),	/* struct s *next;	*/
+			BTF_STRUCT_ENC(NAME_NTH(8), 5, 88),				/* [3] */
+				BTF_MEMBER_ENC(NAME_NTH(7), 4, 0),	/* struct s *next;	*/
 				BTF_MEMBER_ENC(NAME_NTH(1), 5, 64),	/* const int *a;	*/
 				BTF_MEMBER_ENC(NAME_NTH(2), 2, 128),	/* int b[16];		*/
 				BTF_MEMBER_ENC(NAME_NTH(3), 1, 640),	/* int c;		*/
+				BTF_MEMBER_ENC(NAME_NTH(4), 7, 672),	/* float d;		*/
 			/* ptr -> [3] struct s */
 			BTF_PTR_ENC(3),							/* [4] */
 			/* ptr -> [6] const int */
 			BTF_PTR_ENC(6),							/* [5] */
 			/* const -> [1] int */
 			BTF_CONST_ENC(1),						/* [6] */
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(7), 4),				/* [7] */
 			BTF_END_RAW,
 		},
-		BTF_STR_SEC("\0a\0b\0c\0int\0next\0s"),
+		BTF_STR_SEC("\0a\0b\0c\0d\0int\0float\0next\0s"),
 	},
 	.opts = {
 		.dont_resolve_fwds = false,
@@ -6452,9 +6587,10 @@ const struct btf_dedup_test dedup_tests[] = {
 				BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 1),
 				BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 8),
 			BTF_FUNC_ENC(NAME_TBD, 12),					/* [13] func */
+			BTF_TYPE_FLOAT_ENC(NAME_TBD, 2),				/* [14] float */
 			BTF_END_RAW,
 		},
-		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M"),
+		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N"),
 	},
 	.expect = {
 		.raw_types = {
@@ -6477,16 +6613,17 @@ const struct btf_dedup_test dedup_tests[] = {
 				BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 1),
 				BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 8),
 			BTF_FUNC_ENC(NAME_TBD, 12),					/* [13] func */
+			BTF_TYPE_FLOAT_ENC(NAME_TBD, 2),				/* [14] float */
 			BTF_END_RAW,
 		},
-		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M"),
+		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N"),
 	},
 	.opts = {
 		.dont_resolve_fwds = false,
 	},
 },
 {
-	.descr = "dedup: no int duplicates",
+	.descr = "dedup: no int/float duplicates",
 	.input = {
 		.raw_types = {
 			BTF_TYPE_INT_ENC(NAME_NTH(1), BTF_INT_SIGNED, 0, 32, 8),
@@ -6501,9 +6638,15 @@ const struct btf_dedup_test dedup_tests[] = {
 			BTF_TYPE_INT_ENC(NAME_NTH(1), BTF_INT_SIGNED, 0, 27, 8),
 			/* different byte size */
 			BTF_TYPE_INT_ENC(NAME_NTH(1), BTF_INT_SIGNED, 0, 32, 4),
+			/* all allowed sizes */
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 2),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 4),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 8),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 12),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 16),
 			BTF_END_RAW,
 		},
-		BTF_STR_SEC("\0int\0some other int"),
+		BTF_STR_SEC("\0int\0some other int\0float"),
 	},
 	.expect = {
 		.raw_types = {
@@ -6519,9 +6662,15 @@ const struct btf_dedup_test dedup_tests[] = {
 			BTF_TYPE_INT_ENC(NAME_NTH(1), BTF_INT_SIGNED, 0, 27, 8),
 			/* different byte size */
 			BTF_TYPE_INT_ENC(NAME_NTH(1), BTF_INT_SIGNED, 0, 32, 4),
+			/* all allowed sizes */
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 2),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 4),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 8),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 12),
+			BTF_TYPE_FLOAT_ENC(NAME_NTH(3), 16),
 			BTF_END_RAW,
 		},
-		BTF_STR_SEC("\0int\0some other int"),
+		BTF_STR_SEC("\0int\0some other int\0float"),
 	},
 	.opts = {
 		.dont_resolve_fwds = false,
@@ -6633,6 +6782,7 @@ 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);

tools/testing/selftests/bpf/test_btf.h

@@ -66,4 +66,7 @@
 #define BTF_FUNC_ENC(name, func_proto) \
 	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), func_proto)
 
+#define BTF_TYPE_FLOAT_ENC(name, sz) \
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
+
 #endif /* _TEST_BTF_H */