/* 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    0x000fffff
/* Max offset into the string section */
#define BTF_MAX_NAME_OFFSET     0x00ffffff
/* 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 28-30: unused
         * bit     31: kind_flag, currently used by
         *             struct, union and fwd
         */
        __u32 info;
        /* "size" is used by INT, ENUM, STRUCT, UNION and DATASEC.
         * "size" tells the size of the type it is describing.
         *
         * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
         * FUNC, FUNC_PROTO and VAR.
         * "type" is a type_id referring to another type.
         */
        union {
                __u32 size;
                __u32 type;
        };
};

#define BTF_INFO_KIND(info)     (((info) >> 24) & 0x1f)
#define BTF_INFO_VLEN(info)     ((info) & 0xffff)
#define BTF_INFO_KFLAG(info)    ((info) >> 31)

#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_FUNC           12      /* Function     */
#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_MAX            BTF_KIND_FLOAT
#define NR_BTF_KINDS            (BTF_KIND_MAX + 1)

/* 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;
        /* If the type info kind_flag is set, the btf_member offset
         * contains both member bitfield size and bit offset. The
         * bitfield size is set for bitfield members. If the type
         * info kind_flag is not set, the offset contains only bit
         * offset.
         */
        __u32   offset;
};

/* If the struct/union type info kind_flag is set, the
 * following two macros are used to access bitfield_size
 * and bit_offset from btf_member.offset.
 */
#define BTF_MEMBER_BITFIELD_SIZE(val)   ((val) >> 24)
#define BTF_MEMBER_BIT_OFFSET(val)      ((val) & 0xffffff)

/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
 * The exact number of btf_param is stored in the vlen (of the
 * info in "struct btf_type").
 */
struct btf_param {
        __u32   name_off;
        __u32   type;
};

enum {
        BTF_VAR_STATIC = 0,
        BTF_VAR_GLOBAL_ALLOCATED = 1,
        BTF_VAR_GLOBAL_EXTERN = 2,
};

enum btf_func_linkage {
        BTF_FUNC_STATIC = 0,
        BTF_FUNC_GLOBAL = 1,
        BTF_FUNC_EXTERN = 2,
};

/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
 * additional information related to the variable such as its linkage.
 */
struct btf_var {
        __u32   linkage;
};

/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
 * to describe all BTF_KIND_VAR types it contains along with it's
 * in-section offset as well as size.
 */
struct btf_var_secinfo {
        __u32   type;
        __u32   offset;
        __u32   size;
};

#endif /* _UAPI__LINUX_BTF_H__ */