1 //===-- MipsELFObjectWriter.cpp - Mips 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/MipsBaseInfo.h" 11 #include "MCTargetDesc/MipsFixupKinds.h" 12 #include "MCTargetDesc/MipsMCTargetDesc.h" 13 #include "llvm/MC/MCAssembler.h" 14 #include "llvm/MC/MCELFObjectWriter.h" 15 #include "llvm/MC/MCExpr.h" 16 #include "llvm/MC/MCSection.h" 17 #include "llvm/MC/MCValue.h" 18 #include "llvm/Support/ErrorHandling.h" 19 #include <list> 20 21 using namespace llvm; 22 23 namespace { 24 struct RelEntry { 25 RelEntry(const ELFRelocationEntry &R, const MCSymbol *S, int64_t O) : 26 Reloc(R), Sym(S), Offset(O) {} 27 ELFRelocationEntry Reloc; 28 const MCSymbol *Sym; 29 int64_t Offset; 30 }; 31 32 typedef std::list<RelEntry> RelLs; 33 typedef RelLs::iterator RelLsIter; 34 35 class MipsELFObjectWriter : public MCELFObjectTargetWriter { 36 public: 37 MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI, 38 bool _isN64, bool IsLittleEndian); 39 40 virtual ~MipsELFObjectWriter(); 41 42 unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup, 43 bool IsPCRel, bool IsRelocWithSymbol) const override; 44 virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm, 45 const MCValue &Target, 46 const MCFragment &F, 47 const MCFixup &Fixup, 48 bool IsPCRel) const; 49 virtual void sortRelocs(const MCAssembler &Asm, 50 std::vector<ELFRelocationEntry> &Relocs); 51 }; 52 } 53 54 MipsELFObjectWriter::MipsELFObjectWriter(bool _is64Bit, uint8_t OSABI, 55 bool _isN64, bool IsLittleEndian) 56 : MCELFObjectTargetWriter(_is64Bit, OSABI, ELF::EM_MIPS, 57 /*HasRelocationAddend*/ (_isN64) ? true : false, 58 /*IsN64*/ _isN64) {} 59 60 MipsELFObjectWriter::~MipsELFObjectWriter() {} 61 62 const MCSymbol *MipsELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm, 63 const MCValue &Target, 64 const MCFragment &F, 65 const MCFixup &Fixup, 66 bool IsPCRel) const { 67 assert(Target.getSymA() && "SymA cannot be 0."); 68 const MCSymbol &Sym = Target.getSymA()->getSymbol().AliasedSymbol(); 69 70 if (Sym.getSection().getKind().isMergeableCString() || 71 Sym.getSection().getKind().isMergeableConst()) 72 return &Sym; 73 74 return NULL; 75 } 76 77 unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target, 78 const MCFixup &Fixup, 79 bool IsPCRel, 80 bool IsRelocWithSymbol) const { 81 // determine the type of the relocation 82 unsigned Type = (unsigned)ELF::R_MIPS_NONE; 83 unsigned Kind = (unsigned)Fixup.getKind(); 84 85 switch (Kind) { 86 default: 87 llvm_unreachable("invalid fixup kind!"); 88 case FK_Data_4: 89 Type = ELF::R_MIPS_32; 90 break; 91 case FK_Data_8: 92 Type = ELF::R_MIPS_64; 93 break; 94 case FK_GPRel_4: 95 if (isN64()) { 96 Type = setRType((unsigned)ELF::R_MIPS_GPREL32, Type); 97 Type = setRType2((unsigned)ELF::R_MIPS_64, Type); 98 Type = setRType3((unsigned)ELF::R_MIPS_NONE, Type); 99 } 100 else 101 Type = ELF::R_MIPS_GPREL32; 102 break; 103 case Mips::fixup_Mips_GPREL16: 104 Type = ELF::R_MIPS_GPREL16; 105 break; 106 case Mips::fixup_Mips_26: 107 Type = ELF::R_MIPS_26; 108 break; 109 case Mips::fixup_Mips_CALL16: 110 Type = ELF::R_MIPS_CALL16; 111 break; 112 case Mips::fixup_Mips_GOT_Global: 113 case Mips::fixup_Mips_GOT_Local: 114 Type = ELF::R_MIPS_GOT16; 115 break; 116 case Mips::fixup_Mips_HI16: 117 Type = ELF::R_MIPS_HI16; 118 break; 119 case Mips::fixup_Mips_LO16: 120 Type = ELF::R_MIPS_LO16; 121 break; 122 case Mips::fixup_Mips_TLSGD: 123 Type = ELF::R_MIPS_TLS_GD; 124 break; 125 case Mips::fixup_Mips_GOTTPREL: 126 Type = ELF::R_MIPS_TLS_GOTTPREL; 127 break; 128 case Mips::fixup_Mips_TPREL_HI: 129 Type = ELF::R_MIPS_TLS_TPREL_HI16; 130 break; 131 case Mips::fixup_Mips_TPREL_LO: 132 Type = ELF::R_MIPS_TLS_TPREL_LO16; 133 break; 134 case Mips::fixup_Mips_TLSLDM: 135 Type = ELF::R_MIPS_TLS_LDM; 136 break; 137 case Mips::fixup_Mips_DTPREL_HI: 138 Type = ELF::R_MIPS_TLS_DTPREL_HI16; 139 break; 140 case Mips::fixup_Mips_DTPREL_LO: 141 Type = ELF::R_MIPS_TLS_DTPREL_LO16; 142 break; 143 case Mips::fixup_Mips_Branch_PCRel: 144 case Mips::fixup_Mips_PC16: 145 Type = ELF::R_MIPS_PC16; 146 break; 147 case Mips::fixup_Mips_GOT_PAGE: 148 Type = ELF::R_MIPS_GOT_PAGE; 149 break; 150 case Mips::fixup_Mips_GOT_OFST: 151 Type = ELF::R_MIPS_GOT_OFST; 152 break; 153 case Mips::fixup_Mips_GOT_DISP: 154 Type = ELF::R_MIPS_GOT_DISP; 155 break; 156 case Mips::fixup_Mips_GPOFF_HI: 157 Type = setRType((unsigned)ELF::R_MIPS_GPREL16, Type); 158 Type = setRType2((unsigned)ELF::R_MIPS_SUB, Type); 159 Type = setRType3((unsigned)ELF::R_MIPS_HI16, Type); 160 break; 161 case Mips::fixup_Mips_GPOFF_LO: 162 Type = setRType((unsigned)ELF::R_MIPS_GPREL16, Type); 163 Type = setRType2((unsigned)ELF::R_MIPS_SUB, Type); 164 Type = setRType3((unsigned)ELF::R_MIPS_LO16, Type); 165 break; 166 case Mips::fixup_Mips_HIGHER: 167 Type = ELF::R_MIPS_HIGHER; 168 break; 169 case Mips::fixup_Mips_HIGHEST: 170 Type = ELF::R_MIPS_HIGHEST; 171 break; 172 case Mips::fixup_Mips_GOT_HI16: 173 Type = ELF::R_MIPS_GOT_HI16; 174 break; 175 case Mips::fixup_Mips_GOT_LO16: 176 Type = ELF::R_MIPS_GOT_LO16; 177 break; 178 case Mips::fixup_Mips_CALL_HI16: 179 Type = ELF::R_MIPS_CALL_HI16; 180 break; 181 case Mips::fixup_Mips_CALL_LO16: 182 Type = ELF::R_MIPS_CALL_LO16; 183 break; 184 case Mips::fixup_MICROMIPS_26_S1: 185 Type = ELF::R_MICROMIPS_26_S1; 186 break; 187 case Mips::fixup_MICROMIPS_HI16: 188 Type = ELF::R_MICROMIPS_HI16; 189 break; 190 case Mips::fixup_MICROMIPS_LO16: 191 Type = ELF::R_MICROMIPS_LO16; 192 break; 193 case Mips::fixup_MICROMIPS_GOT16: 194 Type = ELF::R_MICROMIPS_GOT16; 195 break; 196 case Mips::fixup_MICROMIPS_PC16_S1: 197 Type = ELF::R_MICROMIPS_PC16_S1; 198 break; 199 case Mips::fixup_MICROMIPS_CALL16: 200 Type = ELF::R_MICROMIPS_CALL16; 201 break; 202 case Mips::fixup_MICROMIPS_GOT_DISP: 203 Type = ELF::R_MICROMIPS_GOT_DISP; 204 break; 205 case Mips::fixup_MICROMIPS_GOT_PAGE: 206 Type = ELF::R_MICROMIPS_GOT_PAGE; 207 break; 208 case Mips::fixup_MICROMIPS_GOT_OFST: 209 Type = ELF::R_MICROMIPS_GOT_OFST; 210 break; 211 case Mips::fixup_MICROMIPS_TLS_GD: 212 Type = ELF::R_MICROMIPS_TLS_GD; 213 break; 214 case Mips::fixup_MICROMIPS_TLS_LDM: 215 Type = ELF::R_MICROMIPS_TLS_LDM; 216 break; 217 case Mips::fixup_MICROMIPS_TLS_DTPREL_HI16: 218 Type = ELF::R_MICROMIPS_TLS_DTPREL_HI16; 219 break; 220 case Mips::fixup_MICROMIPS_TLS_DTPREL_LO16: 221 Type = ELF::R_MICROMIPS_TLS_DTPREL_LO16; 222 break; 223 case Mips::fixup_MICROMIPS_TLS_TPREL_HI16: 224 Type = ELF::R_MICROMIPS_TLS_TPREL_HI16; 225 break; 226 case Mips::fixup_MICROMIPS_TLS_TPREL_LO16: 227 Type = ELF::R_MICROMIPS_TLS_TPREL_LO16; 228 break; 229 } 230 return Type; 231 } 232 233 // Return true if R is either a GOT16 against a local symbol or HI16. 234 static bool NeedsMatchingLo(const MCAssembler &Asm, const RelEntry &R) { 235 if (!R.Sym) 236 return false; 237 238 MCSymbolData &SD = Asm.getSymbolData(R.Sym->AliasedSymbol()); 239 240 return ((R.Reloc.Type == ELF::R_MIPS_GOT16) && !SD.isExternal()) || 241 (R.Reloc.Type == ELF::R_MIPS_HI16); 242 } 243 244 static bool HasMatchingLo(const MCAssembler &Asm, RelLsIter I, RelLsIter Last) { 245 if (I == Last) 246 return false; 247 248 RelLsIter Hi = I++; 249 250 return (I->Reloc.Type == ELF::R_MIPS_LO16) && (Hi->Sym == I->Sym) && 251 (Hi->Offset == I->Offset); 252 } 253 254 static bool HasSameSymbol(const RelEntry &R0, const RelEntry &R1) { 255 return R0.Sym == R1.Sym; 256 } 257 258 static int CompareOffset(const RelEntry &R0, const RelEntry &R1) { 259 return (R0.Offset > R1.Offset) ? 1 : ((R0.Offset == R1.Offset) ? 0 : -1); 260 } 261 262 void MipsELFObjectWriter::sortRelocs(const MCAssembler &Asm, 263 std::vector<ELFRelocationEntry> &Relocs) { 264 // Call the default function first. Relocations are sorted in descending 265 // order of r_offset. 266 MCELFObjectTargetWriter::sortRelocs(Asm, Relocs); 267 268 RelLs RelocLs; 269 std::vector<RelLsIter> Unmatched; 270 271 // Fill RelocLs. Traverse Relocs backwards so that relocations in RelocLs 272 // are in ascending order of r_offset. 273 for (std::vector<ELFRelocationEntry>::reverse_iterator R = Relocs.rbegin(); 274 R != Relocs.rend(); ++R) { 275 std::pair<const MCSymbolRefExpr*, int64_t> P = 276 MipsGetSymAndOffset(*R->Fixup); 277 RelocLs.push_back(RelEntry(*R, P.first ? &P.first->getSymbol() : 0, 278 P.second)); 279 } 280 281 // Get list of unmatched HI16 and GOT16. 282 for (RelLsIter R = RelocLs.begin(); R != RelocLs.end(); ++R) 283 if (NeedsMatchingLo(Asm, *R) && !HasMatchingLo(Asm, R, --RelocLs.end())) 284 Unmatched.push_back(R); 285 286 // Insert unmatched HI16 and GOT16 immediately before their matching LO16. 287 for (std::vector<RelLsIter>::iterator U = Unmatched.begin(); 288 U != Unmatched.end(); ++U) { 289 RelLsIter LoPos = RelocLs.end(), HiPos = *U; 290 bool MatchedLo = false; 291 292 for (RelLsIter R = RelocLs.begin(); R != RelocLs.end(); ++R) { 293 if ((R->Reloc.Type == ELF::R_MIPS_LO16) && HasSameSymbol(*HiPos, *R) && 294 (CompareOffset(*R, *HiPos) >= 0) && 295 ((LoPos == RelocLs.end()) || ((CompareOffset(*R, *LoPos) < 0)) || 296 (!MatchedLo && !CompareOffset(*R, *LoPos)))) 297 LoPos = R; 298 299 MatchedLo = NeedsMatchingLo(Asm, *R) && 300 HasMatchingLo(Asm, R, --RelocLs.end()); 301 } 302 303 // If a matching LoPos was found, move HiPos and insert it before LoPos. 304 // Make the offsets of HiPos and LoPos match. 305 if (LoPos != RelocLs.end()) { 306 HiPos->Offset = LoPos->Offset; 307 RelocLs.insert(LoPos, *HiPos); 308 RelocLs.erase(HiPos); 309 } 310 } 311 312 // Put the sorted list back in reverse order. 313 assert(Relocs.size() == RelocLs.size()); 314 unsigned I = RelocLs.size(); 315 316 for (RelLsIter R = RelocLs.begin(); R != RelocLs.end(); ++R) 317 Relocs[--I] = R->Reloc; 318 } 319 320 MCObjectWriter *llvm::createMipsELFObjectWriter(raw_ostream &OS, 321 uint8_t OSABI, 322 bool IsLittleEndian, 323 bool Is64Bit) { 324 MCELFObjectTargetWriter *MOTW = new MipsELFObjectWriter(Is64Bit, OSABI, 325 (Is64Bit) ? true : false, 326 IsLittleEndian); 327 return createELFObjectWriter(MOTW, OS, IsLittleEndian); 328 } 329