1 files changed, 222 insertions, 0 deletions
diff --git a/llvm/lib/Target/BPF/Disassembler/BPFDisassembler.cpp b/llvm/lib/Target/BPF/Disassembler/BPFDisassembler.cpp
new file mode 100644
index 000000000000..c845524ad657
--- /dev/null
+++ b/llvm/lib/Target/BPF/Disassembler/BPFDisassembler.cpp
@@ -0,0 +1,222 @@
+//===- BPFDisassembler.cpp - Disassembler for BPF ---------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is part of the BPF Disassembler.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/BPFMCTargetDesc.h"
+#include "TargetInfo/BPFTargetInfo.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCDisassembler/MCDisassembler.h"
+#include "llvm/MC/MCFixedLenDisassembler.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/TargetRegistry.h"
+#include <cstdint>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "bpf-disassembler"
+
+typedef MCDisassembler::DecodeStatus DecodeStatus;
+
+namespace {
+
+/// A disassembler class for BPF.
+class BPFDisassembler : public MCDisassembler {
+public:
+  enum BPF_CLASS {
+    BPF_LD = 0x0,
+    BPF_LDX = 0x1,
+    BPF_ST = 0x2,
+    BPF_STX = 0x3,
+    BPF_ALU = 0x4,
+    BPF_JMP = 0x5,
+    BPF_JMP32 = 0x6,
+    BPF_ALU64 = 0x7
+  };
+
+  enum BPF_SIZE {
+    BPF_W = 0x0,
+    BPF_H = 0x1,
+    BPF_B = 0x2,
+    BPF_DW = 0x3
+  };
+
+  enum BPF_MODE {
+    BPF_IMM = 0x0,
+    BPF_ABS = 0x1,
+    BPF_IND = 0x2,
+    BPF_MEM = 0x3,
+    BPF_LEN = 0x4,
+    BPF_MSH = 0x5,
+    BPF_XADD = 0x6
+  };
+
+  BPFDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx)
+      : MCDisassembler(STI, Ctx) {}
+  ~BPFDisassembler() override = default;
+
+  DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
+                              ArrayRef<uint8_t> Bytes, uint64_t Address,
+                              raw_ostream &VStream,
+                              raw_ostream &CStream) const override;
+
+  uint8_t getInstClass(uint64_t Inst) const { return (Inst >> 56) & 0x7; };
+  uint8_t getInstSize(uint64_t Inst) const { return (Inst >> 59) & 0x3; };
+  uint8_t getInstMode(uint64_t Inst) const { return (Inst >> 61) & 0x7; };
+};
+
+} // end anonymous namespace
+
+static MCDisassembler *createBPFDisassembler(const Target &T,
+                                             const MCSubtargetInfo &STI,
+                                             MCContext &Ctx) {
+  return new BPFDisassembler(STI, Ctx);
+}
+
+
+extern "C" void LLVMInitializeBPFDisassembler() {
+  // Register the disassembler.
+  TargetRegistry::RegisterMCDisassembler(getTheBPFTarget(),
+                                         createBPFDisassembler);
+  TargetRegistry::RegisterMCDisassembler(getTheBPFleTarget(),
+                                         createBPFDisassembler);
+  TargetRegistry::RegisterMCDisassembler(getTheBPFbeTarget(),
+                                         createBPFDisassembler);
+}
+
+static const unsigned GPRDecoderTable[] = {
+    BPF::R0,  BPF::R1,  BPF::R2,  BPF::R3,  BPF::R4,  BPF::R5,
+    BPF::R6,  BPF::R7,  BPF::R8,  BPF::R9,  BPF::R10, BPF::R11};
+
+static DecodeStatus DecodeGPRRegisterClass(MCInst &Inst, unsigned RegNo,
+                                           uint64_t /*Address*/,
+                                           const void * /*Decoder*/) {
+  if (RegNo > 11)
+    return MCDisassembler::Fail;
+
+  unsigned Reg = GPRDecoderTable[RegNo];
+  Inst.addOperand(MCOperand::createReg(Reg));
+  return MCDisassembler::Success;
+}
+
+static const unsigned GPR32DecoderTable[] = {
+    BPF::W0,  BPF::W1,  BPF::W2,  BPF::W3,  BPF::W4,  BPF::W5,
+    BPF::W6,  BPF::W7,  BPF::W8,  BPF::W9,  BPF::W10, BPF::W11};
+
+static DecodeStatus DecodeGPR32RegisterClass(MCInst &Inst, unsigned RegNo,
+                                             uint64_t /*Address*/,
+                                             const void * /*Decoder*/) {
+  if (RegNo > 11)
+    return MCDisassembler::Fail;
+
+  unsigned Reg = GPR32DecoderTable[RegNo];
+  Inst.addOperand(MCOperand::createReg(Reg));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus decodeMemoryOpValue(MCInst &Inst, unsigned Insn,
+                                        uint64_t Address, const void *Decoder) {
+  unsigned Register = (Insn >> 16) & 0xf;
+  Inst.addOperand(MCOperand::createReg(GPRDecoderTable[Register]));
+  unsigned Offset = (Insn & 0xffff);
+  Inst.addOperand(MCOperand::createImm(SignExtend32<16>(Offset)));
+
+  return MCDisassembler::Success;
+}
+
+#include "BPFGenDisassemblerTables.inc"
+static DecodeStatus readInstruction64(ArrayRef<uint8_t> Bytes, uint64_t Address,
+                                      uint64_t &Size, uint64_t &Insn,
+                                      bool IsLittleEndian) {
+  uint64_t Lo, Hi;
+
+  if (Bytes.size() < 8) {
+    Size = 0;
+    return MCDisassembler::Fail;
+  }
+
+  Size = 8;
+  if (IsLittleEndian) {
+    Hi = (Bytes[0] << 24) | (Bytes[1] << 16) | (Bytes[2] << 0) | (Bytes[3] << 8);
+    Lo = (Bytes[4] << 0) | (Bytes[5] << 8) | (Bytes[6] << 16) | (Bytes[7] << 24);
+  } else {
+    Hi = (Bytes[0] << 24) | ((Bytes[1] & 0x0F) << 20) | ((Bytes[1] & 0xF0) << 12) |
+         (Bytes[2] << 8) | (Bytes[3] << 0);
+    Lo = (Bytes[4] << 24) | (Bytes[5] << 16) | (Bytes[6] << 8) | (Bytes[7] << 0);
+  }
+  Insn = Make_64(Hi, Lo);
+
+  return MCDisassembler::Success;
+}
+
+DecodeStatus BPFDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
+                                             ArrayRef<uint8_t> Bytes,
+                                             uint64_t Address,
+                                             raw_ostream &VStream,
+                                             raw_ostream &CStream) const {
+  bool IsLittleEndian = getContext().getAsmInfo()->isLittleEndian();
+  uint64_t Insn, Hi;
+  DecodeStatus Result;
+
+  Result = readInstruction64(Bytes, Address, Size, Insn, IsLittleEndian);
+  if (Result == MCDisassembler::Fail) return MCDisassembler::Fail;
+
+  uint8_t InstClass = getInstClass(Insn);
+  uint8_t InstMode = getInstMode(Insn);
+  if ((InstClass == BPF_LDX || InstClass == BPF_STX) &&
+      getInstSize(Insn) != BPF_DW &&
+      (InstMode == BPF_MEM || InstMode == BPF_XADD) &&
+      STI.getFeatureBits()[BPF::ALU32])
+    Result = decodeInstruction(DecoderTableBPFALU3264, Instr, Insn, Address,
+                               this, STI);
+  else
+    Result = decodeInstruction(DecoderTableBPF64, Instr, Insn, Address, this,
+                               STI);
+
+  if (Result == MCDisassembler::Fail) return MCDisassembler::Fail;
+
+  switch (Instr.getOpcode()) {
+  case BPF::LD_imm64:
+  case BPF::LD_pseudo: {
+    if (Bytes.size() < 16) {
+      Size = 0;
+      return MCDisassembler::Fail;
+    }
+    Size = 16;
+    if (IsLittleEndian)
+      Hi = (Bytes[12] << 0) | (Bytes[13] << 8) | (Bytes[14] << 16) | (Bytes[15] << 24);
+    else
+      Hi = (Bytes[12] << 24) | (Bytes[13] << 16) | (Bytes[14] << 8) | (Bytes[15] << 0);
+    auto& Op = Instr.getOperand(1);
+    Op.setImm(Make_64(Hi, Op.getImm()));
+    break;
+  }
+  case BPF::LD_ABS_B:
+  case BPF::LD_ABS_H:
+  case BPF::LD_ABS_W:
+  case BPF::LD_IND_B:
+  case BPF::LD_IND_H:
+  case BPF::LD_IND_W: {
+    auto Op = Instr.getOperand(0);
+    Instr.clear();
+    Instr.addOperand(MCOperand::createReg(BPF::R6));
+    Instr.addOperand(Op);
+    break;
+  }
+  }
+
+  return Result;
+}
+
+typedef DecodeStatus (*DecodeFunc)(MCInst &MI, unsigned insn, uint64_t Address,
+                                   const void *Decoder);