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