bolt/BinarySection.cpp

//===--- BinarySection.cpp  - Interface for object file section -----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//

#include "BinarySection.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCStreamer.h"

using namespace llvm;
using namespace bolt;

Triple::ArchType Relocation::Arch;

bool Relocation::isSupported(uint64_t Type) {
  switch (Type) {
  default:
    return false;
  case ELF::R_X86_64_8:
  case ELF::R_X86_64_16:
  case ELF::R_X86_64_32:
  case ELF::R_X86_64_32S:
  case ELF::R_X86_64_64:
  case ELF::R_X86_64_PC8:
  case ELF::R_X86_64_PC32:
  case ELF::R_X86_64_PC64:
  case ELF::R_X86_64_PLT32:
  case ELF::R_X86_64_GOTPCREL:
  case ELF::R_X86_64_GOTTPOFF:
  case ELF::R_X86_64_TPOFF32:
  case ELF::R_X86_64_GOTPCRELX:
  case ELF::R_X86_64_REX_GOTPCRELX:
  case ELF::R_AARCH64_CALL26:
  case ELF::R_AARCH64_ADR_PREL_PG_HI21:
  case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
  case ELF::R_AARCH64_ADD_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
  case ELF::R_AARCH64_ADR_GOT_PAGE:
  case ELF::R_AARCH64_TLSDESC_ADR_PAGE21:
  case ELF::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_HI12:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
  case ELF::R_AARCH64_LD64_GOT_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_LD64_LO12:
  case ELF::R_AARCH64_TLSDESC_ADD_LO12:
  case ELF::R_AARCH64_TLSDESC_CALL:
  case ELF::R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
  case ELF::R_AARCH64_JUMP26:
  case ELF::R_AARCH64_PREL32:
  case ELF::R_AARCH64_ABS64:
    return true;
  }
}

size_t Relocation::getSizeForType(uint64_t Type) {
  switch (Type) {
  default:
    llvm_unreachable("unsupported relocation type");
  case ELF::R_X86_64_8:
  case ELF::R_X86_64_PC8:
    return 1;
  case ELF::R_X86_64_16:
    return 2;
  case ELF::R_X86_64_PLT32:
  case ELF::R_X86_64_PC32:
  case ELF::R_X86_64_32S:
  case ELF::R_X86_64_32:
  case ELF::R_X86_64_GOTPCREL:
  case ELF::R_X86_64_GOTTPOFF:
  case ELF::R_X86_64_TPOFF32:
  case ELF::R_X86_64_GOTPCRELX:
  case ELF::R_X86_64_REX_GOTPCRELX:
  case ELF::R_AARCH64_CALL26:
  case ELF::R_AARCH64_ADR_PREL_PG_HI21:
  case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
  case ELF::R_AARCH64_ADD_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
  case ELF::R_AARCH64_ADR_GOT_PAGE:
  case ELF::R_AARCH64_TLSDESC_ADR_PAGE21:
  case ELF::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_HI12:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
  case ELF::R_AARCH64_LD64_GOT_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_LD64_LO12:
  case ELF::R_AARCH64_TLSDESC_ADD_LO12:
  case ELF::R_AARCH64_TLSDESC_CALL:
  case ELF::R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
  case ELF::R_AARCH64_JUMP26:
  case ELF::R_AARCH64_PREL32:
    return 4;
  case ELF::R_X86_64_PC64:
  case ELF::R_X86_64_64:
  case ELF::R_AARCH64_ABS64:
    return 8;
  }
}

uint64_t Relocation::extractValue(uint64_t Type, uint64_t Contents,
                                  uint64_t PC) {
  switch (Type) {
  default:
    llvm_unreachable("unsupported relocation type");
  case ELF::R_AARCH64_ABS64:
    return Contents;
  case ELF::R_AARCH64_PREL32:
    return static_cast<int64_t>(PC) + SignExtend64<32>(Contents & 0xffffffff);
  case ELF::R_AARCH64_TLSDESC_CALL:
  case ELF::R_AARCH64_JUMP26:
  case ELF::R_AARCH64_CALL26:
    // Immediate goes in bits 25:0 of B and BL.
    Contents &= ~0xfffffffffc000000ULL;
    return static_cast<int64_t>(PC) + SignExtend64<28>(Contents << 2);
  case ELF::R_AARCH64_ADR_GOT_PAGE:
  case ELF::R_AARCH64_TLSDESC_ADR_PAGE21:
  case ELF::R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
  case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
    // Bits 32:12 of Symbol address goes in bits 30:29 + 23:5 of ADRP
    // instruction
    Contents &= ~0xffffffff9f00001fUll;
    auto LowBits = (Contents >> 29) & 0x3;
    auto HighBits = (Contents >> 5) & 0x7ffff;
    Contents = LowBits | (HighBits << 2);
    Contents = static_cast<int64_t>(PC) + SignExtend64<32>(Contents << 12);
    Contents &= ~0xfffUll;
    return Contents;
  }
  case ELF::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_LD64_LO12:
  case ELF::R_AARCH64_LD64_GOT_LO12_NC:
  case ELF::R_AARCH64_LDST64_ABS_LO12_NC: {
    // Immediate goes in bits 21:10 of LD/ST instruction, taken
    // from bits 11:3 of Symbol address
    Contents &= ~0xffffffffffc003ffU;
    return Contents >> (10 - 3);
  }
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_HI12:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_ADD_LO12:
  case ELF::R_AARCH64_ADD_ABS_LO12_NC: {
    // Immediate goes in bits 21:10 of ADD instruction
    Contents &= ~0xffffffffffc003ffU;
    return Contents >> (10 - 0);
  }
  case ELF::R_AARCH64_LDST128_ABS_LO12_NC: {
    // Immediate goes in bits 21:10 of ADD instruction, taken
    // from bits 11:4 of Symbol address
    Contents &= ~0xffffffffffc003ffU;
    return Contents >> (10 - 4);
  }
  case ELF::R_AARCH64_LDST32_ABS_LO12_NC: {
    // Immediate goes in bits 21:10 of ADD instruction, taken
    // from bits 11:2 of Symbol address
    Contents &= ~0xffffffffffc003ffU;
    return Contents >> (10 - 2);
  }
  case ELF::R_AARCH64_LDST16_ABS_LO12_NC: {
    // Immediate goes in bits 21:10 of ADD instruction, taken
    // from bits 11:1 of Symbol address
    Contents &= ~0xffffffffffc003ffU;
    return Contents >> (10 - 1);
  }
  case ELF::R_AARCH64_LDST8_ABS_LO12_NC: {
    // Immediate goes in bits 21:10 of ADD instruction, taken
    // from bits 11:0 of Symbol address
    Contents &= ~0xffffffffffc003ffU;
    return Contents >> (10 - 0);
  }
  }
}

bool Relocation::isGOT(uint64_t Type) {
  switch (Type) {
  default:
    return false;
  case ELF::R_X86_64_GOT32:
  case ELF::R_X86_64_GOTPCREL:
  case ELF::R_X86_64_GOTTPOFF:
  case ELF::R_X86_64_GOTOFF64:
  case ELF::R_X86_64_GOTPC32:
  case ELF::R_X86_64_GOT64:
  case ELF::R_X86_64_GOTPCREL64:
  case ELF::R_X86_64_GOTPC64:
  case ELF::R_X86_64_GOTPLT64:
  case ELF::R_X86_64_GOTPC32_TLSDESC:
  case ELF::R_X86_64_GOTPCRELX:
  case ELF::R_X86_64_REX_GOTPCRELX:
  case ELF::R_AARCH64_ADR_GOT_PAGE:
  case ELF::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  case ELF::R_AARCH64_LD64_GOT_LO12_NC:
  case ELF::R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_HI12:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_ADR_PAGE21:
  case ELF::R_AARCH64_TLSDESC_LD64_LO12:
  case ELF::R_AARCH64_TLSDESC_ADD_LO12:
  case ELF::R_AARCH64_TLSDESC_CALL:
    return true;
  }
}

bool Relocation::isTLS(uint64_t Type) {
  switch (Type) {
  default:
    return false;
  case ELF::R_X86_64_TPOFF32:
  case ELF::R_X86_64_TPOFF64:
  case ELF::R_X86_64_GOTTPOFF:
  case ELF::R_AARCH64_TLSDESC_ADR_PAGE21:
  case ELF::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_HI12:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_LD64_LO12:
  case ELF::R_AARCH64_TLSDESC_ADD_LO12:
  case ELF::R_AARCH64_TLSDESC_CALL:
  case ELF::R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
    return true;
  }
}

bool Relocation::isPCRelative(uint64_t Type) {
  switch (Type) {
  default:
    llvm_unreachable("Unknown relocation type");

  case ELF::R_X86_64_64:
  case ELF::R_X86_64_32:
  case ELF::R_X86_64_32S:
  case ELF::R_X86_64_16:
  case ELF::R_X86_64_8:
  case ELF::R_X86_64_TPOFF32:
  case ELF::R_AARCH64_ABS64:
  case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
  case ELF::R_AARCH64_ADD_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
  case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
  case ELF::R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_HI12:
  case ELF::R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
  case ELF::R_AARCH64_LD64_GOT_LO12_NC:
  case ELF::R_AARCH64_TLSDESC_LD64_LO12:
  case ELF::R_AARCH64_TLSDESC_ADD_LO12:
    return false;

  case ELF::R_X86_64_PC8:
  case ELF::R_X86_64_PC32:
  case ELF::R_X86_64_GOTPCREL:
  case ELF::R_X86_64_PLT32:
  case ELF::R_X86_64_GOTTPOFF:
  case ELF::R_X86_64_GOTPCRELX:
  case ELF::R_X86_64_REX_GOTPCRELX:
  case ELF::R_AARCH64_TLSDESC_CALL:
  case ELF::R_AARCH64_CALL26:
  case ELF::R_AARCH64_ADR_PREL_PG_HI21:
  case ELF::R_AARCH64_ADR_GOT_PAGE:
  case ELF::R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
  case ELF::R_AARCH64_TLSDESC_ADR_PAGE21:
  case ELF::R_AARCH64_JUMP26:
  case ELF::R_AARCH64_PREL32:
    return true;
  }
}

size_t Relocation::emit(MCStreamer *Streamer) const {
  const auto Size = getSizeForType(Type);
  auto &Ctx = Streamer->getContext();
  if (isPCRelative(Type)) {
    auto *TempLabel = Ctx.createTempSymbol();
    Streamer->EmitLabel(TempLabel);
    auto Value =
      MCBinaryExpr::createSub(MCSymbolRefExpr::create(Symbol, Ctx),
                              MCSymbolRefExpr::create(TempLabel, Ctx),
                              Ctx);
    if (Addend) {
      Value = MCBinaryExpr::createAdd(Value,
                                      MCConstantExpr::create(Addend, Ctx),
                                      Ctx);
    }
    Streamer->EmitValue(Value, Size);
  } else if (Addend) {
    auto Value = MCBinaryExpr::createAdd(MCSymbolRefExpr::create(Symbol, Ctx),
                                         MCConstantExpr::create(Addend, Ctx),
                                         Ctx);
    Streamer->EmitValue(Value, Size);
  } else {
    Streamer->EmitSymbolValue(Symbol, Size);
  }
  return Size;
}

#define ELF_RELOC(name, value) #name,

void Relocation::print(raw_ostream &OS) const {
  static const char *X86RelocNames[] = {
#include "llvm/BinaryFormat/ELFRelocs/x86_64.def"
  };
  static const char *AArch64RelocNames[] = {
#include "llvm/BinaryFormat/ELFRelocs/AArch64.def"
  };
  if (Arch == Triple::aarch64)
    OS << AArch64RelocNames[Type];
  else
    OS << X86RelocNames[Type];
  OS << ", 0x" << Twine::utohexstr(Offset);
  if (Symbol) {
    OS << ", " << Symbol->getName();
  }
  if (int64_t(Addend) < 0)
    OS << ", -0x" << Twine::utohexstr(-int64_t(Addend));
  else
    OS << ", 0x" << Twine::utohexstr(Addend);
  OS << ", 0x" << Twine::utohexstr(Value);
}