lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp

   1 //===-- X86ELFObjectWriter.cpp - X86 ELF Writer ---------------------------===//
   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 #include "MCTargetDesc/X86FixupKinds.h"
  11 #include "MCTargetDesc/X86MCTargetDesc.h"
  12 #include "llvm/MC/MCELFObjectWriter.h"
  13 #include "llvm/MC/MCExpr.h"
  14 #include "llvm/MC/MCValue.h"
  15 #include "llvm/Support/ELF.h"
  16 #include "llvm/Support/ErrorHandling.h"
  17
  18 using namespace llvm;
  19
  20 namespace {
  21   class X86ELFObjectWriter : public MCELFObjectTargetWriter {
  22   public:
  23     X86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine);
  24
  25     virtual ~X86ELFObjectWriter();
  26   protected:
  27     unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
  28                           bool IsPCRel) const override;
  29   };
  30 }
  31
  32 X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
  33                                        uint16_t EMachine)
  34   : MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
  35                             // Only i386 uses Rel instead of RelA.
  36                             /*HasRelocationAddend*/ EMachine != ELF::EM_386) {}
  37
  38 X86ELFObjectWriter::~X86ELFObjectWriter()
  39 {}
  40
  41 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
  42                                           const MCFixup &Fixup,
  43                                           bool IsPCRel) const {
  44   // determine the type of the relocation
  45
  46   MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
  47   if (getEMachine() == ELF::EM_X86_64) {
  48     if (IsPCRel) {
  49       switch ((unsigned)Fixup.getKind()) {
  50       default:
  51         llvm_unreachable("invalid fixup kind!");
  52
  53       case FK_Data_8:
  54         return ELF::R_X86_64_PC64;
  55       case FK_Data_4:
  56         return ELF::R_X86_64_PC32;
  57       case FK_Data_2:
  58         return ELF::R_X86_64_PC16;
  59       case FK_Data_1:
  60         return ELF::R_X86_64_PC8;
  61       case FK_PCRel_8:
  62         assert(Modifier == MCSymbolRefExpr::VK_None);
  63         return ELF::R_X86_64_PC64;
  64       case X86::reloc_signed_4byte:
  65       case X86::reloc_riprel_4byte_movq_load:
  66       case X86::reloc_riprel_4byte:
  67       case FK_PCRel_4:
  68         switch (Modifier) {
  69         default:
  70           llvm_unreachable("Unimplemented");
  71         case MCSymbolRefExpr::VK_None:
  72           return ELF::R_X86_64_PC32;
  73         case MCSymbolRefExpr::VK_PLT:
  74           return ELF::R_X86_64_PLT32;
  75         case MCSymbolRefExpr::VK_GOTPCREL:
  76           return ELF::R_X86_64_GOTPCREL;
  77         case MCSymbolRefExpr::VK_GOTTPOFF:
  78           return ELF::R_X86_64_GOTTPOFF;
  79         case MCSymbolRefExpr::VK_TLSGD:
  80           return ELF::R_X86_64_TLSGD;
  81         case MCSymbolRefExpr::VK_TLSLD:
  82           return ELF::R_X86_64_TLSLD;
  83         }
  84       case FK_PCRel_2:
  85         assert(Modifier == MCSymbolRefExpr::VK_None);
  86         return ELF::R_X86_64_PC16;
  87       case FK_PCRel_1:
  88         assert(Modifier == MCSymbolRefExpr::VK_None);
  89         return ELF::R_X86_64_PC8;
  90       }
  91     }
  92     switch ((unsigned)Fixup.getKind()) {
  93     default:
  94       llvm_unreachable("invalid fixup kind!");
  95     case X86::reloc_global_offset_table8:
  96       return ELF::R_X86_64_GOTPC64;
  97     case X86::reloc_global_offset_table:
  98       return ELF::R_X86_64_GOTPC32;
  99     case FK_Data_8:
 100       switch (Modifier) {
 101       default:
 102         llvm_unreachable("Unimplemented");
 103       case MCSymbolRefExpr::VK_None:
 104         return ELF::R_X86_64_64;
 105       case MCSymbolRefExpr::VK_GOT:
 106         return ELF::R_X86_64_GOT64;
 107       case MCSymbolRefExpr::VK_GOTOFF:
 108         return ELF::R_X86_64_GOTOFF64;
 109       case MCSymbolRefExpr::VK_TPOFF:
 110         return ELF::R_X86_64_TPOFF64;
 111       case MCSymbolRefExpr::VK_DTPOFF:
 112         return ELF::R_X86_64_DTPOFF64;
 113       case MCSymbolRefExpr::VK_SIZE:
 114         return ELF::R_X86_64_SIZE64;
 115       }
 116     case X86::reloc_signed_4byte:
 117       switch (Modifier) {
 118       default:
 119         llvm_unreachable("Unimplemented");
 120       case MCSymbolRefExpr::VK_None:
 121         return ELF::R_X86_64_32S;
 122       case MCSymbolRefExpr::VK_GOT:
 123         return ELF::R_X86_64_GOT32;
 124       case MCSymbolRefExpr::VK_GOTPCREL:
 125         return ELF::R_X86_64_GOTPCREL;
 126       case MCSymbolRefExpr::VK_TPOFF:
 127         return ELF::R_X86_64_TPOFF32;
 128       case MCSymbolRefExpr::VK_DTPOFF:
 129         return ELF::R_X86_64_DTPOFF32;
 130       case MCSymbolRefExpr::VK_SIZE:
 131         return ELF::R_X86_64_SIZE32;
 132       }
 133     case FK_Data_4:
 134       return ELF::R_X86_64_32;
 135     case FK_Data_2:
 136       return ELF::R_X86_64_16;
 137     case FK_PCRel_1:
 138     case FK_Data_1:
 139       return ELF::R_X86_64_8;
 140     }
 141   }
 142   assert(getEMachine() == ELF::EM_386 && "Unsupported ELF machine type.");
 143   if (IsPCRel) {
 144     switch ((unsigned)Fixup.getKind()) {
 145     default:
 146       llvm_unreachable("invalid fixup kind!");
 147
 148     case X86::reloc_global_offset_table:
 149       return ELF::R_386_GOTPC;
 150     case FK_PCRel_1:
 151     case FK_Data_1:
 152       switch (Modifier) {
 153       default:
 154         llvm_unreachable("Unimplemented");
 155       case MCSymbolRefExpr::VK_None:
 156         return ELF::R_386_PC8;
 157       }
 158     case FK_PCRel_2:
 159     case FK_Data_2:
 160       switch (Modifier) {
 161       default:
 162         llvm_unreachable("Unimplemented");
 163       case MCSymbolRefExpr::VK_None:
 164         return ELF::R_386_PC16;
 165       }
 166     case X86::reloc_riprel_4byte:
 167     case X86::reloc_signed_4byte:
 168     case FK_PCRel_4:
 169     case FK_Data_4:
 170       switch (Modifier) {
 171       default:
 172         llvm_unreachable("Unimplemented");
 173       case MCSymbolRefExpr::VK_None:
 174         return ELF::R_386_PC32;
 175       case MCSymbolRefExpr::VK_PLT:
 176         return ELF::R_386_PLT32;
 177       }
 178     }
 179   } else {
 180     switch ((unsigned)Fixup.getKind()) {
 181     default:
 182       llvm_unreachable("invalid fixup kind!");
 183     case X86::reloc_global_offset_table:
 184       return ELF::R_386_GOTPC;
 185
 186     // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
 187     // instead?
 188     case X86::reloc_signed_4byte:
 189     case FK_PCRel_4:
 190     case FK_Data_4:
 191       switch (Modifier) {
 192       default:
 193         llvm_unreachable("Unimplemented");
 194       case MCSymbolRefExpr::VK_None:
 195         return ELF::R_386_32;
 196       case MCSymbolRefExpr::VK_GOT:
 197         return ELF::R_386_GOT32;
 198       case MCSymbolRefExpr::VK_PLT:
 199         return ELF::R_386_PLT32;
 200       case MCSymbolRefExpr::VK_GOTOFF:
 201         return ELF::R_386_GOTOFF;
 202       case MCSymbolRefExpr::VK_TLSGD:
 203         return ELF::R_386_TLS_GD;
 204       case MCSymbolRefExpr::VK_TPOFF:
 205         return ELF::R_386_TLS_LE_32;
 206       case MCSymbolRefExpr::VK_INDNTPOFF:
 207         return ELF::R_386_TLS_IE;
 208       case MCSymbolRefExpr::VK_NTPOFF:
 209         return ELF::R_386_TLS_LE;
 210       case MCSymbolRefExpr::VK_GOTNTPOFF:
 211         return ELF::R_386_TLS_GOTIE;
 212       case MCSymbolRefExpr::VK_TLSLDM:
 213         return ELF::R_386_TLS_LDM;
 214       case MCSymbolRefExpr::VK_DTPOFF:
 215         return ELF::R_386_TLS_LDO_32;
 216       case MCSymbolRefExpr::VK_GOTTPOFF:
 217         return ELF::R_386_TLS_IE_32;
 218       }
 219     case FK_Data_2:
 220       return ELF::R_386_16;
 221     case FK_PCRel_1:
 222     case FK_Data_1:
 223       return ELF::R_386_8;
 224     }
 225   }
 226 }
 227
 228 MCObjectWriter *llvm::createX86ELFObjectWriter(raw_ostream &OS,
 229                                                bool IsELF64,
 230                                                uint8_t OSABI,
 231                                                uint16_t EMachine) {
 232   MCELFObjectTargetWriter *MOTW =
 233     new X86ELFObjectWriter(IsELF64, OSABI, EMachine);
 234   return createELFObjectWriter(MOTW, OS,  /*IsLittleEndian=*/true);
 235 }