//===-- BTF.h --------------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains the layout of .BTF and .BTF.ext ELF sections.
///
/// The binary layout for .BTF section:
/// struct Header
/// Type and Str subsections
/// The Type subsection is a collection of types with type id starting with 1.
/// The Str subsection is simply a collection of strings.
///
/// The binary layout for .BTF.ext section:
/// struct ExtHeader
/// FuncInfo, LineInfo, FieldReloc and ExternReloc subsections
/// The FuncInfo subsection is defined as below:
/// BTFFuncInfo Size
/// struct SecFuncInfo for ELF section #1
/// A number of struct BPFFuncInfo for ELF section #1
/// struct SecFuncInfo for ELF section #2
/// A number of struct BPFFuncInfo for ELF section #2
/// ...
/// The LineInfo subsection is defined as below:
/// BPFLineInfo Size
/// struct SecLineInfo for ELF section #1
/// A number of struct BPFLineInfo for ELF section #1
/// struct SecLineInfo for ELF section #2
/// A number of struct BPFLineInfo for ELF section #2
/// ...
/// The FieldReloc subsection is defined as below:
/// BPFFieldReloc Size
/// struct SecFieldReloc for ELF section #1
/// A number of struct BPFFieldReloc for ELF section #1
/// struct SecFieldReloc for ELF section #2
/// A number of struct BPFFieldReloc for ELF section #2
/// ...
///
/// The section formats are also defined at
/// https://github.com/torvalds/linux/blob/master/include/uapi/linux/btf.h
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_BPF_BTF_H
#define LLVM_LIB_TARGET_BPF_BTF_H
namespace llvm {
namespace BTF {
enum : uint32_t { MAGIC = 0xeB9F, VERSION = 1 };
/// Sizes in bytes of various things in the BTF format.
enum {
HeaderSize = 24,
ExtHeaderSize = 32,
CommonTypeSize = 12,
BTFArraySize = 12,
BTFEnumSize = 8,
BTFMemberSize = 12,
BTFParamSize = 8,
BTFDataSecVarSize = 12,
SecFuncInfoSize = 8,
SecLineInfoSize = 8,
SecFieldRelocSize = 8,
BPFFuncInfoSize = 8,
BPFLineInfoSize = 16,
BPFFieldRelocSize = 16,
};
/// The .BTF section header definition.
struct Header {
uint16_t Magic; ///< Magic value
uint8_t Version; ///< Version number
uint8_t Flags; ///< Extra flags
uint32_t HdrLen; ///< Length of this header
/// All offsets are in bytes relative to the end of this header.
uint32_t TypeOff; ///< Offset of type section
uint32_t TypeLen; ///< Length of type section
uint32_t StrOff; ///< Offset of string section
uint32_t StrLen; ///< Length of string section
};
enum : uint32_t {
MAX_VLEN = 0xffff ///< Max # of struct/union/enum members or func args
};
enum TypeKinds : uint8_t {
#define HANDLE_BTF_KIND(ID, NAME) BTF_KIND_##NAME = ID,
#include "BTF.def"
};
/// The BTF common type definition. Different kinds may have
/// additional information after this structure data.
struct CommonType {
/// Type name offset in the string table.
uint32_t NameOff;
/// "Info" bits arrangement:
/// Bits 0-15: vlen (e.g. # of struct's members)
/// Bits 16-23: unused
/// Bits 24-27: kind (e.g. int, ptr, array...etc)
/// Bits 28-30: unused
/// Bit 31: kind_flag, currently used by
/// struct, union and fwd
uint32_t Info;
/// "Size" is used by INT, ENUM, STRUCT and UNION.
/// "Size" tells the size of the type it is describing.
///
/// "Type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
/// FUNC, FUNC_PROTO and VAR.
/// "Type" is a type_id referring to another type.
union {
uint32_t Size;
uint32_t Type;
};
};
// For some specific BTF_KIND, "struct CommonType" is immediately
// followed by extra data.
// BTF_KIND_INT is followed by a u32 and the following
// is the 32 bits arrangement:
// BTF_INT_ENCODING(VAL) : (((VAL) & 0x0f000000) >> 24)
// BTF_INT_OFFSET(VAL) : (((VAL & 0x00ff0000)) >> 16)
// BTF_INT_BITS(VAL) : ((VAL) & 0x000000ff)
/// Attributes stored in the INT_ENCODING.
enum : uint8_t {
INT_SIGNED = (1 << 0),
INT_CHAR = (1 << 1),
INT_BOOL = (1 << 2)
};
/// BTF_KIND_ENUM is followed by multiple "struct BTFEnum".
/// The exact number of btf_enum is stored in the vlen (of the
/// info in "struct CommonType").
struct BTFEnum {
uint32_t NameOff; ///< Enum name offset in the string table
int32_t Val; ///< Enum member value
};
/// BTF_KIND_ARRAY is followed by one "struct BTFArray".
struct BTFArray {
uint32_t ElemType; ///< Element type
uint32_t IndexType; ///< Index type
uint32_t Nelems; ///< Number of elements for this array
};
/// BTF_KIND_STRUCT and BTF_KIND_UNION are followed
/// by multiple "struct BTFMember". The exact number
/// of BTFMember is stored in the vlen (of the info in
/// "struct CommonType").
///
/// If the struct/union contains any bitfield member,
/// the Offset below represents BitOffset (bits 0 - 23)
/// and BitFieldSize(bits 24 - 31) with BitFieldSize = 0
/// for non bitfield members. Otherwise, the Offset
/// represents the BitOffset.
struct BTFMember {
uint32_t NameOff; ///< Member name offset in the string table
uint32_t Type; ///< Member type
uint32_t Offset; ///< BitOffset or BitFieldSize+BitOffset
};
/// BTF_KIND_FUNC_PROTO are followed by multiple "struct BTFParam".
/// The exist number of BTFParam is stored in the vlen (of the info
/// in "struct CommonType").
struct BTFParam {
uint32_t NameOff;
uint32_t Type;
};
/// BTF_KIND_FUNC can be global, static or extern.
enum : uint8_t {
FUNC_STATIC = 0,
FUNC_GLOBAL = 1,
FUNC_EXTERN = 2,
};
/// Variable scoping information.
enum : uint8_t {
VAR_STATIC = 0, ///< Linkage: InternalLinkage
VAR_GLOBAL_ALLOCATED = 1, ///< Linkage: ExternalLinkage
VAR_GLOBAL_EXTERNAL = 2, ///< Linkage: ExternalLinkage
};
/// BTF_KIND_DATASEC are followed by multiple "struct BTFDataSecVar".
/// The exist number of BTFDataSec is stored in the vlen (of the info
/// in "struct CommonType").
struct BTFDataSec {
uint32_t Type; ///< A BTF_KIND_VAR type
uint32_t Offset; ///< In-section offset
uint32_t Size; ///< Occupied memory size
};
/// The .BTF.ext section header definition.
struct ExtHeader {
uint16_t Magic;
uint8_t Version;
uint8_t Flags;
uint32_t HdrLen;
uint32_t FuncInfoOff; ///< Offset of func info section
uint32_t FuncInfoLen; ///< Length of func info section
uint32_t LineInfoOff; ///< Offset of line info section
uint32_t LineInfoLen; ///< Length of line info section
uint32_t FieldRelocOff; ///< Offset of offset reloc section
uint32_t FieldRelocLen; ///< Length of offset reloc section
};
/// Specifying one function info.
struct BPFFuncInfo {
uint32_t InsnOffset; ///< Byte offset in the section
uint32_t TypeId; ///< Type id referring to .BTF type section
};
/// Specifying function info's in one section.
struct SecFuncInfo {
uint32_t SecNameOff; ///< Section name index in the .BTF string table
uint32_t NumFuncInfo; ///< Number of func info's in this section
};
/// Specifying one line info.
struct BPFLineInfo {
uint32_t InsnOffset; ///< Byte offset in this section
uint32_t FileNameOff; ///< File name index in the .BTF string table
uint32_t LineOff; ///< Line index in the .BTF string table
uint32_t LineCol; ///< Line num: line_col >> 10,
/// col num: line_col & 0x3ff
};
/// Specifying line info's in one section.
struct SecLineInfo {
uint32_t SecNameOff; ///< Section name index in the .BTF string table
uint32_t NumLineInfo; ///< Number of line info's in this section
};
/// Specifying one offset relocation.
struct BPFFieldReloc {
uint32_t InsnOffset; ///< Byte offset in this section
uint32_t TypeID; ///< TypeID for the relocation
uint32_t OffsetNameOff; ///< The string to traverse types
uint32_t RelocKind; ///< What to patch the instruction
};
/// Specifying offset relocation's in one section.
struct SecFieldReloc {
uint32_t SecNameOff; ///< Section name index in the .BTF string table
uint32_t NumFieldReloc; ///< Number of offset reloc's in this section
};
} // End namespace BTF.
} // End namespace llvm.
#endif