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- /* Declarations and definitions relating to the BPF Type Format (BTF).
- Copyright (C) 2021-2022 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 24-28: kind
- - bits 29-30: 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) & 0x1f)
- /* 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_FLOAT 16 /* Floating point. */
- #define BTF_KIND_MAX BTF_KIND_FLOAT
- #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_ */
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