include/uapi/linux/btf.h

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 /* Copyright (c) 2018 Facebook */
   3 #ifndef __LINUX_BTF_H__
   4 #define __LINUX_BTF_H__
   5
   6 #include <linux/types.h>
   7
   8 #define BTF_MAGIC       0xeB9F
   9 #define BTF_VERSION     1
  10
  11 struct 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
  31 struct 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, UNION and DATASEC.
  43          * "size" tells the size of the type it is describing.
  44          *
  45          * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
  46          * FUNC, FUNC_PROTO and VAR.
  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_VAR            14      /* Variable     */
  74 #define BTF_KIND_DATASEC        15      /* Section      */
  75 #define BTF_KIND_MAX            BTF_KIND_DATASEC
  76 #define NR_BTF_KINDS            (BTF_KIND_MAX + 1)
  77
  78 /* For some specific BTF_KIND, "struct btf_type" is immediately
  79  * followed by extra data.
  80  */
  81
  82 /* BTF_KIND_INT is followed by a u32 and the following
  83  * is the 32 bits arrangement:
  84  */
  85 #define BTF_INT_ENCODING(VAL)   (((VAL) & 0x0f000000) >> 24)
  86 #define BTF_INT_OFFSET(VAL)     (((VAL) & 0x00ff0000) >> 16)
  87 #define BTF_INT_BITS(VAL)       ((VAL)  & 0x000000ff)
  88
  89 /* Attributes stored in the BTF_INT_ENCODING */
  90 #define BTF_INT_SIGNED  (1 << 0)
  91 #define BTF_INT_CHAR    (1 << 1)
  92 #define BTF_INT_BOOL    (1 << 2)
  93
  94 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
  95  * The exact number of btf_enum is stored in the vlen (of the
  96  * info in "struct btf_type").
  97  */
  98 struct btf_enum {
  99         __u32   name_off;
 100         __s32   val;
 101 };
 102
 103 /* BTF_KIND_ARRAY is followed by one "struct btf_array" */
 104 struct btf_array {
 105         __u32   type;
 106         __u32   index_type;
 107         __u32   nelems;
 108 };
 109
 110 /* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
 111  * by multiple "struct btf_member".  The exact number
 112  * of btf_member is stored in the vlen (of the info in
 113  * "struct btf_type").
 114  */
 115 struct btf_member {
 116         __u32   name_off;
 117         __u32   type;
 118         /* If the type info kind_flag is set, the btf_member offset
 119          * contains both member bitfield size and bit offset. The
 120          * bitfield size is set for bitfield members. If the type
 121          * info kind_flag is not set, the offset contains only bit
 122          * offset.
 123          */
 124         __u32   offset;
 125 };
 126
 127 /* If the struct/union type info kind_flag is set, the
 128  * following two macros are used to access bitfield_size
 129  * and bit_offset from btf_member.offset.
 130  */
 131 #define BTF_MEMBER_BITFIELD_SIZE(val)   ((val) >> 24)
 132 #define BTF_MEMBER_BIT_OFFSET(val)      ((val) & 0xffffff)
 133
 134 /* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
 135  * The exact number of btf_param is stored in the vlen (of the
 136  * info in "struct btf_type").
 137  */
 138 struct btf_param {
 139         __u32   name_off;
 140         __u32   type;
 141 };
 142
 143 enum {
 144         BTF_VAR_STATIC = 0,
 145         BTF_VAR_GLOBAL_ALLOCATED,
 146 };
 147
 148 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
 149  * additional information related to the variable such as its linkage.
 150  */
 151 struct btf_var {
 152         __u32   linkage;
 153 };
 154
 155 /* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
 156  * to describe all BTF_KIND_VAR types it contains along with it's
 157  * in-section offset as well as size.
 158  */
 159 struct btf_var_secinfo {
 160         __u32   type;
 161         __u32   offset;
 162         __u32   size;
 163 };
 164
 165 #endif /* __LINUX_BTF_H__ */