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