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     virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
  28                                   bool IsPCRel, bool IsRelocWithSymbol,
  29                                   int64_t Addend) const;
  30   };
  31 }
  32
  33 X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
  34                                        uint16_t EMachine)
  35   : MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
  36                             // Only i386 uses Rel instead of RelA.
  37                             /*HasRelocationAddend*/ EMachine != ELF::EM_386) {}
  38
  39 X86ELFObjectWriter::~X86ELFObjectWriter()
  40 {}
  41
  42 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
  43                                           const MCFixup &Fixup,
  44                                           bool IsPCRel,
  45                                           bool IsRelocWithSymbol,
  46                                           int64_t Addend) const {
  47   // determine the type of the relocation
  48
  49   MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
  50     MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
  51   unsigned Type;
  52   if (getEMachine() == ELF::EM_X86_64) {
  53     if (IsPCRel) {
  54       switch ((unsigned)Fixup.getKind()) {
  55       default: llvm_unreachable("invalid fixup kind!");
  56
  57       case FK_Data_8: Type = ELF::R_X86_64_PC64; break;
  58       case FK_Data_4: Type = ELF::R_X86_64_PC32; break;
  59       case FK_Data_2: Type = ELF::R_X86_64_PC16; break;
  60
  61       case FK_PCRel_8:
  62         assert(Modifier == MCSymbolRefExpr::VK_None);
  63         Type = ELF::R_X86_64_PC64;
  64         break;
  65       case X86::reloc_signed_4byte:
  66       case X86::reloc_riprel_4byte_movq_load:
  67       case X86::reloc_riprel_4byte:
  68       case FK_PCRel_4:
  69         switch (Modifier) {
  70         default:
  71           llvm_unreachable("Unimplemented");
  72         case MCSymbolRefExpr::VK_None:
  73           Type = ELF::R_X86_64_PC32;
  74           break;
  75         case MCSymbolRefExpr::VK_PLT:
  76           Type = ELF::R_X86_64_PLT32;
  77           break;
  78         case MCSymbolRefExpr::VK_GOTPCREL:
  79           Type = ELF::R_X86_64_GOTPCREL;
  80           break;
  81         case MCSymbolRefExpr::VK_GOTTPOFF:
  82           Type = ELF::R_X86_64_GOTTPOFF;
  83         break;
  84         case MCSymbolRefExpr::VK_TLSGD:
  85           Type = ELF::R_X86_64_TLSGD;
  86           break;
  87         case MCSymbolRefExpr::VK_TLSLD:
  88           Type = ELF::R_X86_64_TLSLD;
  89           break;
  90         }
  91         break;
  92       case FK_PCRel_2:
  93         assert(Modifier == MCSymbolRefExpr::VK_None);
  94         Type = ELF::R_X86_64_PC16;
  95         break;
  96       case FK_PCRel_1:
  97         assert(Modifier == MCSymbolRefExpr::VK_None);
  98         Type = ELF::R_X86_64_PC8;
  99         break;
 100       }
 101     } else {
 102       switch ((unsigned)Fixup.getKind()) {
 103       default: llvm_unreachable("invalid fixup kind!");
 104       case FK_Data_8:
 105         switch (Modifier) {
 106         default:
 107           llvm_unreachable("Unimplemented");
 108         case MCSymbolRefExpr::VK_None:
 109           Type = ELF::R_X86_64_64;
 110           break;
 111         case MCSymbolRefExpr::VK_DTPOFF:
 112           Type = ELF::R_X86_64_DTPOFF64;
 113           break;
 114         }
 115         break;
 116       case X86::reloc_signed_4byte:
 117         switch (Modifier) {
 118         default:
 119           llvm_unreachable("Unimplemented");
 120         case MCSymbolRefExpr::VK_None:
 121           Type = ELF::R_X86_64_32S;
 122           break;
 123         case MCSymbolRefExpr::VK_GOT:
 124           Type = ELF::R_X86_64_GOT32;
 125           break;
 126         case MCSymbolRefExpr::VK_GOTPCREL:
 127           Type = ELF::R_X86_64_GOTPCREL;
 128           break;
 129         case MCSymbolRefExpr::VK_TPOFF:
 130           Type = ELF::R_X86_64_TPOFF32;
 131           break;
 132         case MCSymbolRefExpr::VK_DTPOFF:
 133           Type = ELF::R_X86_64_DTPOFF32;
 134           break;
 135         }
 136         break;
 137       case FK_Data_4:
 138         Type = ELF::R_X86_64_32;
 139         break;
 140       case FK_Data_2: Type = ELF::R_X86_64_16; break;
 141       case FK_PCRel_1:
 142       case FK_Data_1: Type = ELF::R_X86_64_8; break;
 143       }
 144     }
 145   } else if (getEMachine() == ELF::EM_386) {
 146     if (IsPCRel) {
 147       switch ((unsigned)Fixup.getKind()) {
 148       default: llvm_unreachable("invalid fixup kind!");
 149
 150       case X86::reloc_global_offset_table:
 151         Type = ELF::R_386_GOTPC;
 152         break;
 153
 154       case X86::reloc_signed_4byte:
 155       case FK_PCRel_4:
 156       case FK_Data_4:
 157         switch (Modifier) {
 158         default:
 159           llvm_unreachable("Unimplemented");
 160         case MCSymbolRefExpr::VK_None:
 161           Type = ELF::R_386_PC32;
 162           break;
 163         case MCSymbolRefExpr::VK_PLT:
 164           Type = ELF::R_386_PLT32;
 165           break;
 166         }
 167         break;
 168       }
 169     } else {
 170       switch ((unsigned)Fixup.getKind()) {
 171       default: llvm_unreachable("invalid fixup kind!");
 172
 173       case X86::reloc_global_offset_table:
 174         Type = ELF::R_386_GOTPC;
 175         break;
 176
 177       // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
 178       // instead?
 179       case X86::reloc_signed_4byte:
 180       case FK_PCRel_4:
 181       case FK_Data_4:
 182         switch (Modifier) {
 183         default:
 184           llvm_unreachable("Unimplemented");
 185         case MCSymbolRefExpr::VK_None:
 186           Type = ELF::R_386_32;
 187           break;
 188         case MCSymbolRefExpr::VK_GOT:
 189           Type = ELF::R_386_GOT32;
 190           break;
 191         case MCSymbolRefExpr::VK_GOTOFF:
 192           Type = ELF::R_386_GOTOFF;
 193           break;
 194         case MCSymbolRefExpr::VK_TLSGD:
 195           Type = ELF::R_386_TLS_GD;
 196           break;
 197         case MCSymbolRefExpr::VK_TPOFF:
 198           Type = ELF::R_386_TLS_LE_32;
 199           break;
 200         case MCSymbolRefExpr::VK_INDNTPOFF:
 201           Type = ELF::R_386_TLS_IE;
 202           break;
 203         case MCSymbolRefExpr::VK_NTPOFF:
 204           Type = ELF::R_386_TLS_LE;
 205           break;
 206         case MCSymbolRefExpr::VK_GOTNTPOFF:
 207           Type = ELF::R_386_TLS_GOTIE;
 208           break;
 209         case MCSymbolRefExpr::VK_TLSLDM:
 210           Type = ELF::R_386_TLS_LDM;
 211           break;
 212         case MCSymbolRefExpr::VK_DTPOFF:
 213           Type = ELF::R_386_TLS_LDO_32;
 214           break;
 215         case MCSymbolRefExpr::VK_GOTTPOFF:
 216           Type = ELF::R_386_TLS_IE_32;
 217           break;
 218         }
 219         break;
 220       case FK_Data_2: Type = ELF::R_386_16; break;
 221       case FK_PCRel_1:
 222       case FK_Data_1: Type = ELF::R_386_8; break;
 223       }
 224     }
 225   } else
 226     llvm_unreachable("Unsupported ELF machine type.");
 227
 228   return Type;
 229 }
 230
 231 MCObjectWriter *llvm::createX86ELFObjectWriter(raw_ostream &OS,
 232                                                bool IsELF64,
 233                                                uint8_t OSABI,
 234                                                uint16_t EMachine) {
 235   MCELFObjectTargetWriter *MOTW =
 236     new X86ELFObjectWriter(IsELF64, OSABI, EMachine);
 237   return createELFObjectWriter(MOTW, OS,  /*IsLittleEndian=*/true);
 238 }