LXR linux/tools/include/uapi/linux/btf.h

   1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2/* Copyright (c) 2018 Facebook */
   3#ifndef _UAPI__LINUX_BTF_H__
   4#define _UAPI__LINUX_BTF_H__
   5
   6#include <linux/types.h>
   7
   8#define BTF_MAGIC       0xeB9F
   9#define BTF_VERSION     1
  10
  11struct btf_header {
  12        __u16   magic;
  13        __u8    version;
  14        __u8    flags;
  15        __u32   hdr_len;
  16
  17        /* All offsets are in bytes relative to the end of this header */
  18        __u32   type_off;       /* offset of type section       */
  19        __u32   type_len;       /* length of type section       */
  20        __u32   str_off;        /* offset of string section     */
  21        __u32   str_len;        /* length of string section     */
  22};
  23
  24/* Max # of type identifier */
  25#define BTF_MAX_TYPE    0x0000ffff
  26/* Max offset into the string section */
  27#define BTF_MAX_NAME_OFFSET     0x0000ffff
  28/* Max # of struct/union/enum members or func args */
  29#define BTF_MAX_VLEN    0xffff
  30
  31struct btf_type {
  32        __u32 name_off;
  33        /* "info" bits arrangement
  34         * bits  0-15: vlen (e.g. # of struct's members)
  35         * bits 16-23: unused
  36         * bits 24-27: kind (e.g. int, ptr, array...etc)
  37         * bits 28-30: unused
  38         * bit     31: kind_flag, currently used by
  39         *             struct, union and fwd
  40         */
  41        __u32 info;
  42        /* "size" is used by INT, ENUM, STRUCT and UNION.
  43         * "size" tells the size of the type it is describing.
  44         *
  45         * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
  46         * FUNC and FUNC_PROTO.
  47         * "type" is a type_id referring to another type.
  48         */
  49        union {
  50                __u32 size;
  51                __u32 type;
  52        };
  53};
  54
  55#define BTF_INFO_KIND(info)     (((info) >> 24) & 0x0f)
  56#define BTF_INFO_VLEN(info)     ((info) & 0xffff)
  57#define BTF_INFO_KFLAG(info)    ((info) >> 31)
  58
  59#define BTF_KIND_UNKN           0       /* Unknown      */
  60#define BTF_KIND_INT            1       /* Integer      */
  61#define BTF_KIND_PTR            2       /* Pointer      */
  62#define BTF_KIND_ARRAY          3       /* Array        */
  63#define BTF_KIND_STRUCT         4       /* Struct       */
  64#define BTF_KIND_UNION          5       /* Union        */
  65#define BTF_KIND_ENUM           6       /* Enumeration  */
  66#define BTF_KIND_FWD            7       /* Forward      */
  67#define BTF_KIND_TYPEDEF        8       /* Typedef      */
  68#define BTF_KIND_VOLATILE       9       /* Volatile     */
  69#define BTF_KIND_CONST          10      /* Const        */
  70#define BTF_KIND_RESTRICT       11      /* Restrict     */
  71#define BTF_KIND_FUNC           12      /* Function     */
  72#define BTF_KIND_FUNC_PROTO     13      /* Function Proto       */
  73#define BTF_KIND_MAX            13
  74#define NR_BTF_KINDS            14
  75
  76/* For some specific BTF_KIND, "struct btf_type" is immediately
  77 * followed by extra data.
  78 */
  79
  80/* BTF_KIND_INT is followed by a u32 and the following
  81 * is the 32 bits arrangement:
  82 */
  83#define BTF_INT_ENCODING(VAL)   (((VAL) & 0x0f000000) >> 24)
  84#define BTF_INT_OFFSET(VAL)     (((VAL  & 0x00ff0000)) >> 16)
  85#define BTF_INT_BITS(VAL)       ((VAL)  & 0x000000ff)
  86
  87/* Attributes stored in the BTF_INT_ENCODING */
  88#define BTF_INT_SIGNED  (1 << 0)
  89#define BTF_INT_CHAR    (1 << 1)
  90#define BTF_INT_BOOL    (1 << 2)
  91
  92/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
  93 * The exact number of btf_enum is stored in the vlen (of the
  94 * info in "struct btf_type").
  95 */
  96struct btf_enum {
  97        __u32   name_off;
  98        __s32   val;
  99};
 100
 101/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
 102struct btf_array {
 103        __u32   type;
 104        __u32   index_type;
 105        __u32   nelems;
 106};
 107
 108/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
 109 * by multiple "struct btf_member".  The exact number
 110 * of btf_member is stored in the vlen (of the info in
 111 * "struct btf_type").
 112 */
 113struct btf_member {
 114        __u32   name_off;
 115        __u32   type;
 116        /* If the type info kind_flag is set, the btf_member offset
 117         * contains both member bitfield size and bit offset. The
 118         * bitfield size is set for bitfield members. If the type
 119         * info kind_flag is not set, the offset contains only bit
 120         * offset.
 121         */
 122        __u32   offset;
 123};
 124
 125/* If the struct/union type info kind_flag is set, the
 126 * following two macros are used to access bitfield_size
 127 * and bit_offset from btf_member.offset.
 128 */
 129#define BTF_MEMBER_BITFIELD_SIZE(val)   ((val) >> 24)
 130#define BTF_MEMBER_BIT_OFFSET(val)      ((val) & 0xffffff)
 131
 132/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
 133 * The exact number of btf_param is stored in the vlen (of the
 134 * info in "struct btf_type").
 135 */
 136struct btf_param {
 137        __u32   name_off;
 138        __u32   type;
 139};
 140
 141#endif /* _UAPI__LINUX_BTF_H__ */
 142