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Diffstat (limited to 'include/btf.h')
| -rw-r--r-- | include/btf.h | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/include/btf.h b/include/btf.h new file mode 100644 index 0000000..3b1a4c3 --- /dev/null +++ b/include/btf.h @@ -0,0 +1,196 @@ +/* Declarations and definitions relating to the BPF Type Format (BTF). + Copyright (C) 2021 Free Software Foundation, Inc. + + This file is part of GCC. + + GCC is free software; you can redistribute it and/or modify it + under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3, or (at your option) + any later version. + + GCC is distributed in the hope that it will be useful, but WITHOUT + ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public + License for more details. + + You should have received a copy of the GNU General Public License + along with GCC; see the file COPYING3. If not see + <http://www.gnu.org/licenses/>. */ + +/* This file is derived from the BTF specification described in the + Linux kernel source tree (linux/Documentation/bpf/btf.rst). */ + +#ifndef _BTF_H_ +#define _BTF_H_ + +#include <stdint.h> + +#ifdef __cplusplus +extern "C" +{ +#endif + +/* BTF magic number to identify header, endianness. */ +#define BTF_MAGIC 0xeb9f +/* Data format version number. */ +#define BTF_VERSION 1 + +struct btf_header +{ + uint16_t magic; /* Magic number (BTF_MAGIC). */ + uint8_t version; /* Data format version (BTF_VERSION). */ + uint8_t flags; /* Flags. Currently unused. */ + uint32_t hdr_len; /* Length of this header (sizeof (struct btf_header)). */ + + /* Following offsets are relative to the end of this header. */ + uint32_t type_off; /* Offset of type section, in bytes. */ + uint32_t type_len; /* Length of type section, in bytes. */ + uint32_t str_off; /* Offset of string section, in bytes. */ + uint32_t str_len; /* Length of string section, in bytes. */ +}; + +/* Maximum type identifier. */ +#define BTF_MAX_TYPE 0x000fffff +/* Maximum offset into the string section. */ +#define BTF_MAX_NAME_OFFSET 0x00ffffff +/* Maximum number of struct, union, enum members or func args. */ +#define BTF_MAX_VLEN 0xffff + +struct btf_type +{ + uint32_t name_off; /* Offset in string section of type name. */ + uint32_t info; /* Encoded kind, variant length, kind flag: + - bits 0-15: vlen + - bits 16-23: unused + - bits 24-27: kind + - bits 28-30: unused + - bit 31: kind_flag + See accessor macros below. */ + + /* SIZE is used by INT, ENUM, STRUCT, UNION, DATASEC kinds. + TYPE is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT, FUNC, + FUNC_PROTO and VAR kinds. */ + union + { + uint32_t size; /* Size of the entire type, in bytes. */ + uint32_t type; /* A type_id referring to another type. */ + }; +}; + +/* The folloing macros access the information encoded in btf_type.info. */ +/* Type kind. See below. */ +#define BTF_INFO_KIND(info) (((info) >> 24) & 0x0f) +/* Number of entries of variable length data following certain type kinds. + For example, number of structure members, number of function parameters. */ +#define BTF_INFO_VLEN(info) ((info) & 0xffff) +/* For BTF_KIND_FWD, 1 if forward to union, 0 if forward to struct. + For BTF_KIND_STRUCT and BTF_KIND_UNION, 1 if the struct/union contains + a bitfield. */ +#define BTF_INFO_KFLAG(info) ((info) >> 31) + +/* Encoding for struct btf_type.info. */ +#define BTF_TYPE_INFO(kind, kflag, vlen) \ + ((((kflag) ? 1 : 0 ) << 31) | ((kind) << 24) | ((vlen) & 0xffff)) + +#define BTF_KIND_UNKN 0 /* Unknown or invalid. */ +#define BTF_KIND_INT 1 /* Integer. */ +#define BTF_KIND_PTR 2 /* Pointer. */ +#define BTF_KIND_ARRAY 3 /* Array. */ +#define BTF_KIND_STRUCT 4 /* Struct. */ +#define BTF_KIND_UNION 5 /* Union. */ +#define BTF_KIND_ENUM 6 /* Enumeration. */ +#define BTF_KIND_FWD 7 /* Forward. */ +#define BTF_KIND_TYPEDEF 8 /* Typedef. */ +#define BTF_KIND_VOLATILE 9 /* Referenced type is volatile. */ +#define BTF_KIND_CONST 10 /* Referenced type is const. */ +#define BTF_KIND_RESTRICT 11 /* Restrict. */ +#define BTF_KIND_FUNC 12 /* Subprogram. */ +#define BTF_KIND_FUNC_PROTO 13 /* Function Prototype. */ +#define BTF_KIND_VAR 14 /* Variable. */ +#define BTF_KIND_DATASEC 15 /* Section such as .bss or .data. */ +#define BTF_KIND_MAX BTF_KIND_DATASEC +#define NR_BTF_KINDS (BTF_KIND_MAX + 1) + +/* For some BTF_KINDs, struct btf_type is immediately followed by + additional data describing the type. */ + +/* BTF_KIND_INT is followed by a 32-bit word, with the following + bit arrangement. */ +#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24) +#define BTF_INT_OFFSET(VAL) (((VAL) & 0x00ff0000) >> 16) +#define BTF_INT_BITS(VAL) ((VAL) & 0x000000ff) + +#define BTF_INT_DATA(encoding, offset, bits) \ + ((((encoding) & 0x0f) << 24) | (((offset) & 0xff) << 16) | ((bits) & 0xff)) + +/* BTF_INT_ENCODING holds the following attribute flags. */ +#define BTF_INT_SIGNED (1 << 0) +#define BTF_INT_CHAR (1 << 1) +#define BTF_INT_BOOL (1 << 2) + +/* BTF_KIND_ENUM is followed by VLEN struct btf_enum entries, + which describe the enumerators. Note that BTF currently only + supports signed 32-bit enumerator values. */ +struct btf_enum +{ + uint32_t name_off; /* Offset in string section of enumerator name. */ + int32_t val; /* Enumerator value. */ +}; + +/* BTF_KIND_ARRAY is followed by a single struct btf_array. */ +struct btf_array +{ + uint32_t type; /* Type of array elements. */ + uint32_t index_type; /* Type of array index. */ + uint32_t nelems; /* Number of elements. 0 for unsized/variable length. */ +}; + +/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed by VLEN + struct btf_member. */ +struct btf_member +{ + uint32_t name_off; /* Offset in string section of member name. */ + uint32_t type; /* Type of member. */ + uint32_t offset; /* If the type info kind_flag is set, this contains + both the member bitfield size and bit offset, + according to the macros below. If kind_flag is not + set, offset contains only the bit offset (from the + beginning of the struct). */ +}; + +/* If struct or union type info kind_flag is set, used to access member + bitfield size from btf_member.offset. */ +#define BTF_MEMBER_BITFIELD_SIZE (val) ((val) >> 24) +/* If struct or union type info kind_flag is set, used to access member + bit offset from btf_member.offset. */ +#define BTF_MEMBER_BIT_OFFSET (val) ((val) & 0x00ffffff) + +/* BTF_KIND_FUNC_PROTO is followed by VLEN struct btf_param entries, which + describe the types of the function parameters. */ +struct btf_param +{ + uint32_t name_off; /* Offset in string section of parameter name. */ + uint32_t type; /* Type of parameter. */ +}; + +/* BTF_KIND_VAR is followed by a single struct btf_var, which describes + information about the variable. */ +struct btf_var +{ + uint32_t linkage; /* Currently only 0=static or 1=global. */ +}; + +/* BTF_KIND_DATASEC is followed by VLEN struct btf_var_secinfo entries, + which describe all BTF_KIND_VAR types contained in the section. */ +struct btf_var_secinfo +{ + uint32_t type; /* Type of variable. */ + uint32_t offset; /* In-section offset of variable (in bytes). */ + uint32_t size; /* Size (in bytes) of variable. */ +}; + +#ifdef __cplusplus +} +#endif + +#endif /* _BTF_H_ */ |