btf.h (5590B) - Raw
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 0x000fffff 26 /* Max offset into the string section */ 27 #define BTF_MAX_NAME_OFFSET 0x00ffffff 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 24-28: kind (e.g. int, ptr, array...etc) 37 * bits 29-30: unused 38 * bit 31: kind_flag, currently used by 39 * struct, union, enum, fwd and enum64 40 */ 41 __u32 info; 42 /* "size" is used by INT, ENUM, STRUCT, UNION, DATASEC and ENUM64. 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, VAR, DECL_TAG and TYPE_TAG. 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) & 0x1f) 56 #define BTF_INFO_VLEN(info) ((info) & 0xffff) 57 #define BTF_INFO_KFLAG(info) ((info) >> 31) 58 59 enum { 60 BTF_KIND_UNKN = 0, /* Unknown */ 61 BTF_KIND_INT = 1, /* Integer */ 62 BTF_KIND_PTR = 2, /* Pointer */ 63 BTF_KIND_ARRAY = 3, /* Array */ 64 BTF_KIND_STRUCT = 4, /* Struct */ 65 BTF_KIND_UNION = 5, /* Union */ 66 BTF_KIND_ENUM = 6, /* Enumeration up to 32-bit values */ 67 BTF_KIND_FWD = 7, /* Forward */ 68 BTF_KIND_TYPEDEF = 8, /* Typedef */ 69 BTF_KIND_VOLATILE = 9, /* Volatile */ 70 BTF_KIND_CONST = 10, /* Const */ 71 BTF_KIND_RESTRICT = 11, /* Restrict */ 72 BTF_KIND_FUNC = 12, /* Function */ 73 BTF_KIND_FUNC_PROTO = 13, /* Function Proto */ 74 BTF_KIND_VAR = 14, /* Variable */ 75 BTF_KIND_DATASEC = 15, /* Section */ 76 BTF_KIND_FLOAT = 16, /* Floating point */ 77 BTF_KIND_DECL_TAG = 17, /* Decl Tag */ 78 BTF_KIND_TYPE_TAG = 18, /* Type Tag */ 79 BTF_KIND_ENUM64 = 19, /* Enumeration up to 64-bit values */ 80 81 NR_BTF_KINDS, 82 BTF_KIND_MAX = NR_BTF_KINDS - 1, 83 }; 84 85 /* For some specific BTF_KIND, "struct btf_type" is immediately 86 * followed by extra data. 87 */ 88 89 /* BTF_KIND_INT is followed by a u32 and the following 90 * is the 32 bits arrangement: 91 */ 92 #define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24) 93 #define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16) 94 #define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff) 95 96 /* Attributes stored in the BTF_INT_ENCODING */ 97 #define BTF_INT_SIGNED (1 << 0) 98 #define BTF_INT_CHAR (1 << 1) 99 #define BTF_INT_BOOL (1 << 2) 100 101 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum". 102 * The exact number of btf_enum is stored in the vlen (of the 103 * info in "struct btf_type"). 104 */ 105 struct btf_enum { 106 __u32 name_off; 107 __s32 val; 108 }; 109 110 /* BTF_KIND_ARRAY is followed by one "struct btf_array" */ 111 struct btf_array { 112 __u32 type; 113 __u32 index_type; 114 __u32 nelems; 115 }; 116 117 /* BTF_KIND_STRUCT and BTF_KIND_UNION are followed 118 * by multiple "struct btf_member". The exact number 119 * of btf_member is stored in the vlen (of the info in 120 * "struct btf_type"). 121 */ 122 struct btf_member { 123 __u32 name_off; 124 __u32 type; 125 /* If the type info kind_flag is set, the btf_member offset 126 * contains both member bitfield size and bit offset. The 127 * bitfield size is set for bitfield members. If the type 128 * info kind_flag is not set, the offset contains only bit 129 * offset. 130 */ 131 __u32 offset; 132 }; 133 134 /* If the struct/union type info kind_flag is set, the 135 * following two macros are used to access bitfield_size 136 * and bit_offset from btf_member.offset. 137 */ 138 #define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24) 139 #define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff) 140 141 /* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param". 142 * The exact number of btf_param is stored in the vlen (of the 143 * info in "struct btf_type"). 144 */ 145 struct btf_param { 146 __u32 name_off; 147 __u32 type; 148 }; 149 150 enum { 151 BTF_VAR_STATIC = 0, 152 BTF_VAR_GLOBAL_ALLOCATED = 1, 153 BTF_VAR_GLOBAL_EXTERN = 2, 154 }; 155 156 enum btf_func_linkage { 157 BTF_FUNC_STATIC = 0, 158 BTF_FUNC_GLOBAL = 1, 159 BTF_FUNC_EXTERN = 2, 160 }; 161 162 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe 163 * additional information related to the variable such as its linkage. 164 */ 165 struct btf_var { 166 __u32 linkage; 167 }; 168 169 /* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo" 170 * to describe all BTF_KIND_VAR types it contains along with it's 171 * in-section offset as well as size. 172 */ 173 struct btf_var_secinfo { 174 __u32 type; 175 __u32 offset; 176 __u32 size; 177 }; 178 179 /* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe 180 * additional information related to the tag applied location. 181 * If component_idx == -1, the tag is applied to a struct, union, 182 * variable or function. Otherwise, it is applied to a struct/union 183 * member or a func argument, and component_idx indicates which member 184 * or argument (0 ... vlen-1). 185 */ 186 struct btf_decl_tag { 187 __s32 component_idx; 188 }; 189 190 /* BTF_KIND_ENUM64 is followed by multiple "struct btf_enum64". 191 * The exact number of btf_enum64 is stored in the vlen (of the 192 * info in "struct btf_type"). 193 */ 194 struct btf_enum64 { 195 __u32 name_off; 196 __u32 val_lo32; 197 __u32 val_hi32; 198 }; 199 200 #endif /* __LINUX_BTF_H__ */