LXR linux/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 28-31: 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 */
  90struct btf_enum {
  91        __u32   name_off;
  92        __s32   val;
  93};
  94
  95/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
  96struct 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 */
 107struct btf_member {
 108        __u32   name_off;
 109        __u32   type;
 110        __u32   offset; /* offset in bits */
 111};
 112
 113#endif /* _UAPI__LINUX_BTF_H__ */
 114