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 28-31: unused
  38          */
  39         __u32 info;
  40         /* "size" is used by INT, ENUM, STRUCT and UNION.
  41          * "size" tells the size of the type it is describing.
  42          *
  43          * "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.
  44          * "type" is a type_id referring to another type.
  45          */
  46         union {
  47                 __u32 size;
  48                 __u32 type;
  49         };
  50 };
  51
  52 #define BTF_INFO_KIND(info)     (((info) >> 24) & 0x0f)
  53 #define BTF_INFO_VLEN(info)     ((info) & 0xffff)
  54
  55 #define BTF_KIND_UNKN           0       /* Unknown      */
  56 #define BTF_KIND_INT            1       /* Integer      */
  57 #define BTF_KIND_PTR            2       /* Pointer      */
  58 #define BTF_KIND_ARRAY          3       /* Array        */
  59 #define BTF_KIND_STRUCT         4       /* Struct       */
  60 #define BTF_KIND_UNION          5       /* Union        */
  61 #define BTF_KIND_ENUM           6       /* Enumeration  */
  62 #define BTF_KIND_FWD            7       /* Forward      */
  63 #define BTF_KIND_TYPEDEF        8       /* Typedef      */
  64 #define BTF_KIND_VOLATILE       9       /* Volatile     */
  65 #define BTF_KIND_CONST          10      /* Const        */
  66 #define BTF_KIND_RESTRICT       11      /* Restrict     */
  67 #define BTF_KIND_MAX            11
  68 #define NR_BTF_KINDS            12
  69
  70 /* For some specific BTF_KIND, "struct btf_type" is immediately
  71  * followed by extra data.
  72  */
  73
  74 /* BTF_KIND_INT is followed by a u32 and the following
  75  * is the 32 bits arrangement:
  76  */
  77 #define BTF_INT_ENCODING(VAL)   (((VAL) & 0x0f000000) >> 24)
  78 #define BTF_INT_OFFSET(VAL)     (((VAL  & 0x00ff0000)) >> 16)
  79 #define BTF_INT_BITS(VAL)       ((VAL)  & 0x000000ff)
  80
  81 /* Attributes stored in the BTF_INT_ENCODING */
  82 #define BTF_INT_SIGNED  (1 << 0)
  83 #define BTF_INT_CHAR    (1 << 1)
  84 #define BTF_INT_BOOL    (1 << 2)
  85
  86 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
  87  * The exact number of btf_enum is stored in the vlen (of the
  88  * info in "struct btf_type").
  89  */
  90 struct btf_enum {
  91         __u32   name_off;
  92         __s32   val;
  93 };
  94
  95 /* BTF_KIND_ARRAY is followed by one "struct btf_array" */
  96 struct btf_array {
  97         __u32   type;
  98         __u32   index_type;
  99         __u32   nelems;
 100 };
 101
 102 /* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
 103  * by multiple "struct btf_member".  The exact number
 104  * of btf_member is stored in the vlen (of the info in
 105  * "struct btf_type").
 106  */
 107 struct btf_member {
 108         __u32   name_off;
 109         __u32   type;
 110         __u32   offset; /* offset in bits */
 111 };
 112
 113 #endif /* __LINUX_BTF_H__ */