/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */

/* Copyright (c) 2018 Facebook */

#ifndef __LINUX_BTF_H__

#define __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) & 0x0f)

#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_MAX		BTF_KIND_DATASEC

#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 /* __LINUX_BTF_H__ */