v4.19.13 snapshot.
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
new file mode 100644
index 0000000..972265f
--- /dev/null
+++ b/include/uapi/linux/btf.h
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (c) 2018 Facebook */
+#ifndef _UAPI__LINUX_BTF_H__
+#define _UAPI__LINUX_BTF_H__
+
+#include <linux/types.h>
+
+#define BTF_MAGIC 0xeB9F
+#define BTF_VERSION 1
+
+struct btf_header {
+ __u16 magic;
+ __u8 version;
+ __u8 flags;
+ __u32 hdr_len;
+
+ /* All offsets are in bytes relative to the end of this header */
+ __u32 type_off; /* offset of type section */
+ __u32 type_len; /* length of type section */
+ __u32 str_off; /* offset of string section */
+ __u32 str_len; /* length of string section */
+};
+
+/* Max # of type identifier */
+#define BTF_MAX_TYPE 0x0000ffff
+/* Max offset into the string section */
+#define BTF_MAX_NAME_OFFSET 0x0000ffff
+/* Max # of struct/union/enum members or func args */
+#define BTF_MAX_VLEN 0xffff
+
+struct btf_type {
+ __u32 name_off;
+ /* "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 28-31: unused
+ */
+ __u32 info;
+ /* "size" is used by INT, ENUM, STRUCT and UNION.
+ * "size" tells the size of the type it is describing.
+ *
+ * "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.
+ * "type" is a type_id referring to another type.
+ */
+ union {
+ __u32 size;
+ __u32 type;
+ };
+};
+
+#define BTF_INFO_KIND(info) (((info) >> 24) & 0x0f)
+#define BTF_INFO_VLEN(info) ((info) & 0xffff)
+
+#define BTF_KIND_UNKN 0 /* Unknown */
+#define BTF_KIND_INT 1 /* Integer */
+#define BTF_KIND_PTR 2 /* Pointer */
+#define BTF_KIND_ARRAY 3 /* Array */
+#define BTF_KIND_STRUCT 4 /* Struct */
+#define BTF_KIND_UNION 5 /* Union */
+#define BTF_KIND_ENUM 6 /* Enumeration */
+#define BTF_KIND_FWD 7 /* Forward */
+#define BTF_KIND_TYPEDEF 8 /* Typedef */
+#define BTF_KIND_VOLATILE 9 /* Volatile */
+#define BTF_KIND_CONST 10 /* Const */
+#define BTF_KIND_RESTRICT 11 /* Restrict */
+#define BTF_KIND_MAX 11
+#define NR_BTF_KINDS 12
+
+/* For some specific BTF_KIND, "struct btf_type" is immediately
+ * followed by extra data.
+ */
+
+/* BTF_KIND_INT is followed by a u32 and the following
+ * is the 32 bits arrangement:
+ */
+#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24)
+#define BTF_INT_OFFSET(VAL) (((VAL & 0x00ff0000)) >> 16)
+#define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff)
+
+/* Attributes stored in the BTF_INT_ENCODING */
+#define BTF_INT_SIGNED (1 << 0)
+#define BTF_INT_CHAR (1 << 1)
+#define BTF_INT_BOOL (1 << 2)
+
+/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
+ * The exact number of btf_enum is stored in the vlen (of the
+ * info in "struct btf_type").
+ */
+struct btf_enum {
+ __u32 name_off;
+ __s32 val;
+};
+
+/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
+struct btf_array {
+ __u32 type;
+ __u32 index_type;
+ __u32 nelems;
+};
+
+/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
+ * by multiple "struct btf_member". The exact number
+ * of btf_member is stored in the vlen (of the info in
+ * "struct btf_type").
+ */
+struct btf_member {
+ __u32 name_off;
+ __u32 type;
+ __u32 offset; /* offset in bits */
+};
+
+#endif /* _UAPI__LINUX_BTF_H__ */