1 //===-- BPFMCCodeEmitter.cpp - Convert BPF code to machine code -----------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the BPFMCCodeEmitter class. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "MCTargetDesc/BPFMCTargetDesc.h" 15 #include "llvm/MC/MCCodeEmitter.h" 16 #include "llvm/MC/MCFixup.h" 17 #include "llvm/MC/MCInst.h" 18 #include "llvm/MC/MCInstrInfo.h" 19 #include "llvm/MC/MCRegisterInfo.h" 20 #include "llvm/MC/MCSubtargetInfo.h" 21 #include "llvm/MC/MCSymbol.h" 22 #include "llvm/ADT/Statistic.h" 23 #include "llvm/Support/EndianStream.h" 24 #include "llvm/Support/raw_ostream.h" 25 using namespace llvm; 26 27 #define DEBUG_TYPE "mccodeemitter" 28 29 namespace { 30 class BPFMCCodeEmitter : public MCCodeEmitter { 31 BPFMCCodeEmitter(const BPFMCCodeEmitter &) = delete; 32 void operator=(const BPFMCCodeEmitter &) = delete; 33 const MCRegisterInfo &MRI; 34 bool IsLittleEndian; 35 36 public: 37 BPFMCCodeEmitter(const MCRegisterInfo &mri, bool IsLittleEndian) 38 : MRI(mri), IsLittleEndian(IsLittleEndian) {} 39 40 ~BPFMCCodeEmitter() {} 41 42 // getBinaryCodeForInstr - TableGen'erated function for getting the 43 // binary encoding for an instruction. 44 uint64_t getBinaryCodeForInstr(const MCInst &MI, 45 SmallVectorImpl<MCFixup> &Fixups, 46 const MCSubtargetInfo &STI) const; 47 48 // getMachineOpValue - Return binary encoding of operand. If the machin 49 // operand requires relocation, record the relocation and return zero. 50 unsigned getMachineOpValue(const MCInst &MI, const MCOperand &MO, 51 SmallVectorImpl<MCFixup> &Fixups, 52 const MCSubtargetInfo &STI) const; 53 54 uint64_t getMemoryOpValue(const MCInst &MI, unsigned Op, 55 SmallVectorImpl<MCFixup> &Fixups, 56 const MCSubtargetInfo &STI) const; 57 58 void encodeInstruction(const MCInst &MI, raw_ostream &OS, 59 SmallVectorImpl<MCFixup> &Fixups, 60 const MCSubtargetInfo &STI) const override; 61 }; 62 } 63 64 MCCodeEmitter *llvm::createBPFMCCodeEmitter(const MCInstrInfo &MCII, 65 const MCRegisterInfo &MRI, 66 MCContext &Ctx) { 67 return new BPFMCCodeEmitter(MRI, true); 68 } 69 70 MCCodeEmitter *llvm::createBPFbeMCCodeEmitter(const MCInstrInfo &MCII, 71 const MCRegisterInfo &MRI, 72 MCContext &Ctx) { 73 return new BPFMCCodeEmitter(MRI, false); 74 } 75 76 unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI, 77 const MCOperand &MO, 78 SmallVectorImpl<MCFixup> &Fixups, 79 const MCSubtargetInfo &STI) const { 80 if (MO.isReg()) 81 return MRI.getEncodingValue(MO.getReg()); 82 if (MO.isImm()) 83 return static_cast<unsigned>(MO.getImm()); 84 85 assert(MO.isExpr()); 86 87 const MCExpr *Expr = MO.getExpr(); 88 89 assert(Expr->getKind() == MCExpr::SymbolRef); 90 91 if (MI.getOpcode() == BPF::JAL) 92 // func call name 93 Fixups.push_back(MCFixup::create(0, Expr, FK_SecRel_4)); 94 else if (MI.getOpcode() == BPF::LD_imm64) 95 Fixups.push_back(MCFixup::create(0, Expr, FK_SecRel_8)); 96 else 97 // bb label 98 Fixups.push_back(MCFixup::create(0, Expr, FK_PCRel_2)); 99 100 return 0; 101 } 102 103 static uint8_t SwapBits(uint8_t Val) 104 { 105 return (Val & 0x0F) << 4 | (Val & 0xF0) >> 4; 106 } 107 108 void BPFMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS, 109 SmallVectorImpl<MCFixup> &Fixups, 110 const MCSubtargetInfo &STI) const { 111 unsigned Opcode = MI.getOpcode(); 112 support::endian::Writer<support::little> LE(OS); 113 support::endian::Writer<support::big> BE(OS); 114 115 if (Opcode == BPF::LD_imm64 || Opcode == BPF::LD_pseudo) { 116 uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI); 117 LE.write<uint8_t>(Value >> 56); 118 if (IsLittleEndian) 119 LE.write<uint8_t>((Value >> 48) & 0xff); 120 else 121 LE.write<uint8_t>(SwapBits((Value >> 48) & 0xff)); 122 LE.write<uint16_t>(0); 123 if (IsLittleEndian) 124 LE.write<uint32_t>(Value & 0xffffFFFF); 125 else 126 BE.write<uint32_t>(Value & 0xffffFFFF); 127 128 const MCOperand &MO = MI.getOperand(1); 129 uint64_t Imm = MO.isImm() ? MO.getImm() : 0; 130 LE.write<uint8_t>(0); 131 LE.write<uint8_t>(0); 132 LE.write<uint16_t>(0); 133 if (IsLittleEndian) 134 LE.write<uint32_t>(Imm >> 32); 135 else 136 BE.write<uint32_t>(Imm >> 32); 137 } else { 138 // Get instruction encoding and emit it 139 uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI); 140 LE.write<uint8_t>(Value >> 56); 141 if (IsLittleEndian) { 142 LE.write<uint8_t>((Value >> 48) & 0xff); 143 LE.write<uint16_t>((Value >> 32) & 0xffff); 144 LE.write<uint32_t>(Value & 0xffffFFFF); 145 } else { 146 LE.write<uint8_t>(SwapBits((Value >> 48) & 0xff)); 147 BE.write<uint16_t>((Value >> 32) & 0xffff); 148 BE.write<uint32_t>(Value & 0xffffFFFF); 149 } 150 } 151 } 152 153 // Encode BPF Memory Operand 154 uint64_t BPFMCCodeEmitter::getMemoryOpValue(const MCInst &MI, unsigned Op, 155 SmallVectorImpl<MCFixup> &Fixups, 156 const MCSubtargetInfo &STI) const { 157 uint64_t Encoding; 158 const MCOperand Op1 = MI.getOperand(1); 159 assert(Op1.isReg() && "First operand is not register."); 160 Encoding = MRI.getEncodingValue(Op1.getReg()); 161 Encoding <<= 16; 162 MCOperand Op2 = MI.getOperand(2); 163 assert(Op2.isImm() && "Second operand is not immediate."); 164 Encoding |= Op2.getImm() & 0xffff; 165 return Encoding; 166 } 167 168 #include "BPFGenMCCodeEmitter.inc" 169
