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 11 /* 12 * BTF layout section consists of a struct btf_layout for each known 13 * kind at BTF encoding time. 14 */ 15 struct btf_layout { 16 __u8 info_sz; /* size of singular element after btf_type */ 17 __u8 elem_sz; /* size of each of btf_vlen(t) elements */ 18 __u16 flags; /* currently unused */ 19 }; 20 21 struct btf_header { 22 __u16 magic; 23 __u8 version; 24 __u8 flags; 25 __u32 hdr_len; 26 27 /* All offsets are in bytes relative to the end of this header */ 28 __u32 type_off; /* offset of type section */ 29 __u32 type_len; /* length of type section */ 30 __u32 str_off; /* offset of string section */ 31 __u32 str_len; /* length of string section */ 32 __u32 layout_off; /* offset of layout section */ 33 __u32 layout_len; /* length of layout section */ 34 }; 35 36 enum btf_max { 37 /* Max possible kind */ 38 BTF_MAX_KIND = 0x0000007f, 39 /* Max # of type identifier */ 40 BTF_MAX_TYPE = 0x000fffff, 41 /* Max offset into the string section */ 42 BTF_MAX_NAME_OFFSET = 0x00ffffff, 43 /* Max # of struct/union/enum members or func args */ 44 BTF_MAX_VLEN = 0x00ffffff, 45 }; 46 47 struct btf_type { 48 __u32 name_off; 49 /* "info" bits arrangement 50 * bits 0-23: vlen (e.g. # of struct's members) 51 * bits 24-30: kind (e.g. int, ptr, array...etc) 52 * bit 31: kind_flag, currently used by 53 * struct, union, enum, fwd, enum64, 54 * decl_tag and type_tag 55 */ 56 __u32 info; 57 /* "size" is used by INT, ENUM, STRUCT, UNION, DATASEC, ENUM64 58 * and LOC_PARAM. "size" tells the size of the type it is describing. 59 * 60 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT, 61 * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG. 62 * "type" is a type_id referring to another type. 63 */ 64 union { 65 __u32 size; 66 __u32 type; 67 }; 68 }; 69 70 #define BTF_INFO_KIND(info) (((info) >> 24) & 0x7f) 71 #define BTF_INFO_VLEN(info) ((info) & 0xffffff) 72 #define BTF_INFO_KFLAG(info) ((info) >> 31) 73 74 enum { 75 BTF_KIND_UNKN = 0, /* Unknown */ 76 BTF_KIND_INT = 1, /* Integer */ 77 BTF_KIND_PTR = 2, /* Pointer */ 78 BTF_KIND_ARRAY = 3, /* Array */ 79 BTF_KIND_STRUCT = 4, /* Struct */ 80 BTF_KIND_UNION = 5, /* Union */ 81 BTF_KIND_ENUM = 6, /* Enumeration up to 32-bit values */ 82 BTF_KIND_FWD = 7, /* Forward */ 83 BTF_KIND_TYPEDEF = 8, /* Typedef */ 84 BTF_KIND_VOLATILE = 9, /* Volatile */ 85 BTF_KIND_CONST = 10, /* Const */ 86 BTF_KIND_RESTRICT = 11, /* Restrict */ 87 BTF_KIND_FUNC = 12, /* Function */ 88 BTF_KIND_FUNC_PROTO = 13, /* Function Proto */ 89 BTF_KIND_VAR = 14, /* Variable */ 90 BTF_KIND_DATASEC = 15, /* Section */ 91 BTF_KIND_FLOAT = 16, /* Floating point */ 92 BTF_KIND_DECL_TAG = 17, /* Decl Tag */ 93 BTF_KIND_TYPE_TAG = 18, /* Type Tag */ 94 BTF_KIND_ENUM64 = 19, /* Enumeration up to 64-bit values */ 95 BTF_KIND_LOC_PARAM = 20, /* Location parameter information */ 96 BTF_KIND_LOC_PROTO = 21, /* Location prototype for site */ 97 BTF_KIND_LOCSEC = 22, /* Location section */ 98 NR_BTF_KINDS, 99 BTF_KIND_MAX = NR_BTF_KINDS - 1, 100 }; 101 102 /* For some specific BTF_KIND, "struct btf_type" is immediately 103 * followed by extra data. 104 */ 105 106 /* BTF_KIND_INT is followed by a u32 and the following 107 * is the 32 bits arrangement: 108 */ 109 #define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24) 110 #define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16) 111 #define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff) 112 113 /* Attributes stored in the BTF_INT_ENCODING */ 114 #define BTF_INT_SIGNED (1 << 0) 115 #define BTF_INT_CHAR (1 << 1) 116 #define BTF_INT_BOOL (1 << 2) 117 118 /* BTF_KIND_ENUM is followed by multiple "struct btf_enum". 119 * The exact number of btf_enum is stored in the vlen (of the 120 * info in "struct btf_type"). 121 */ 122 struct btf_enum { 123 __u32 name_off; 124 __s32 val; 125 }; 126 127 /* BTF_KIND_ARRAY is followed by one "struct btf_array" */ 128 struct btf_array { 129 __u32 type; 130 __u32 index_type; 131 __u32 nelems; 132 }; 133 134 /* BTF_KIND_STRUCT and BTF_KIND_UNION are followed 135 * by multiple "struct btf_member". The exact number 136 * of btf_member is stored in the vlen (of the info in 137 * "struct btf_type"). 138 */ 139 struct btf_member { 140 __u32 name_off; 141 __u32 type; 142 /* If the type info kind_flag is set, the btf_member offset 143 * contains both member bitfield size and bit offset. The 144 * bitfield size is set for bitfield members. If the type 145 * info kind_flag is not set, the offset contains only bit 146 * offset. 147 */ 148 __u32 offset; 149 }; 150 151 /* If the struct/union type info kind_flag is set, the 152 * following two macros are used to access bitfield_size 153 * and bit_offset from btf_member.offset. 154 */ 155 #define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24) 156 #define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff) 157 158 /* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param". 159 * The exact number of btf_param is stored in the vlen (of the 160 * info in "struct btf_type"). 161 */ 162 struct btf_param { 163 __u32 name_off; 164 __u32 type; 165 }; 166 167 enum { 168 BTF_VAR_STATIC = 0, 169 BTF_VAR_GLOBAL_ALLOCATED = 1, 170 BTF_VAR_GLOBAL_EXTERN = 2, 171 }; 172 173 enum btf_func_linkage { 174 BTF_FUNC_STATIC = 0, 175 BTF_FUNC_GLOBAL = 1, 176 BTF_FUNC_EXTERN = 2, 177 }; 178 179 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe 180 * additional information related to the variable such as its linkage. 181 */ 182 struct btf_var { 183 __u32 linkage; 184 }; 185 186 /* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo" 187 * to describe all BTF_KIND_VAR types it contains along with it's 188 * in-section offset as well as size. 189 */ 190 struct btf_var_secinfo { 191 __u32 type; 192 __u32 offset; 193 __u32 size; 194 }; 195 196 /* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe 197 * additional information related to the tag applied location. 198 * If component_idx == -1, the tag is applied to a struct, union, 199 * variable or function. Otherwise, it is applied to a struct/union 200 * member or a func argument, and component_idx indicates which member 201 * or argument (0 ... vlen-1). 202 */ 203 struct btf_decl_tag { 204 __s32 component_idx; 205 }; 206 207 /* BTF_KIND_ENUM64 is followed by multiple "struct btf_enum64". 208 * The exact number of btf_enum64 is stored in the vlen (of the 209 * info in "struct btf_type"). 210 */ 211 struct btf_enum64 { 212 __u32 name_off; 213 __u32 val_lo32; 214 __u32 val_hi32; 215 }; 216 217 /* 218 * BTF_KIND_LOC_PARAM is followed by a single "struct btf_loc_param" 219 * that contains flags specifying the contents of the vlen-specified 220 * number of 4-byte values that follow. 221 */ 222 struct btf_loc_param { 223 __u32 flags; 224 __u32 values[]; 225 }; 226 227 /* 228 * The combination of size, vlen and flags gives us the means to interpret 229 * the following vlen-specified set of 4-byte values: 230 * 231 * - a BTF_LOC_PARAM_CONST is a constant value; combination 232 * of size, vlen and _SIGNED flag determines it. If the value requires 233 * 64 bits it is stored in {lo,hi} order. 234 * - a BTF_LOC_PARAM_ADDR|BTF_LOC_PARAM_CONST is an address that should be 235 * normalized with respect to kernel/module base address. 236 * - a BTF_LOC_PARAM_REG with vlen 1 is a simple register number; 237 * with vlen 2 it is a multi-register parameter. Register numbers are 238 * numbers derived from DW_OP_reg values, i.e. 0 is DW_OP_reg0; since 239 * DW_OP_fbreg has its own special DW_OP_value and DW_OP_regx can refer 240 * to an arbitrary register number, we reserve BTF_LOC_PARAM_FBREG for 241 * the frame base register to avoid collisions. 242 * - a _REG | OFFSET describes an address without dereferencing it. 243 * - a _REG | DEREF with vlen 1 dereferences the value in the register 244 * number specified. 245 * - a REG | DEREF | OFFSET with vlen > 1 specifies the register number 246 * in the first 4-byte value and the offset in the remainder. 247 * In the case of REG and OFFSET combinations, the OFFSET has the width 248 * of the value words while the type size describes the represented parameter, 249 * so for example a REG | DEREF | OFFSET with size 8 and vlen 2 would be 250 * an 8-byte register dereference with signed 4-byte offset, since the vlen 2 251 * values consist of a register value and the signed value. 252 */ 253 enum btf_loc_param_flags { 254 BTF_LOC_PARAM_SIGNED = 0x1, 255 BTF_LOC_PARAM_CONST = 0x2, 256 BTF_LOC_PARAM_ADDR = 0x4, 257 BTF_LOC_PARAM_REG = 0x8, 258 BTF_LOC_PARAM_DEREF = 0x10, 259 BTF_LOC_PARAM_OFFSET = 0x20, 260 }; 261 262 enum { 263 BTF_LOC_PARAM_FBREG = 0xffffffff 264 }; 265 266 /* 267 * BTF_KIND_LOC_PROTO specifies location prototypes; i.e. how locations relate 268 * to parameters; a struct btf_type of BTF_KIND_LOC_PROTO is followed by a 269 * vlen-specified number of __u32 BTF type ids which specify the associated 270 * BTF_KIND_LOC_PARAM for each function parameter associated with the 271 * location. The type should either be 0 (no location info) or point at 272 * a BTF_KIND_LOC_PARAM. 273 */ 274 275 /* 276 * BTF_KIND_LOCSEC consists of vlen-specified number of "struct btf_loc" 277 * containing location site-specific information for a specific ELF section; 278 * for example locations in ".text" are in a LOCSEC named "inline.text". 279 * 280 * - function (func) 281 * - location prototype type id (loc_proto) 282 * - address offset (offset) relative to the runtime base address of the 283 * ELF section associated with the LOCSEC 284 */ 285 286 struct btf_loc { 287 __u32 func; 288 __u32 loc_proto; 289 __u32 offset; 290 }; 291 292 #endif /* _UAPI__LINUX_BTF_H__ */ 293