lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp

   1 //===-- PPCELFObjectWriter.cpp - PPC ELF Writer ---------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "MCTargetDesc/PPCFixupKinds.h"
  10 #include "MCTargetDesc/PPCMCExpr.h"
  11 #include "MCTargetDesc/PPCMCTargetDesc.h"
  12 #include "llvm/ADT/STLExtras.h"
  13 #include "llvm/MC/MCELFObjectWriter.h"
  14 #include "llvm/MC/MCExpr.h"
  15 #include "llvm/MC/MCObjectWriter.h"
  16 #include "llvm/MC/MCSymbolELF.h"
  17 #include "llvm/MC/MCValue.h"
  18 #include "llvm/Support/ErrorHandling.h"
  19
  20 using namespace llvm;
  21
  22 namespace {
  23   class PPCELFObjectWriter : public MCELFObjectTargetWriter {
  24   public:
  25     PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI);
  26
  27   protected:
  28     unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
  29                           const MCFixup &Fixup, bool IsPCRel) const override;
  30
  31     bool needsRelocateWithSymbol(const MCSymbol &Sym,
  32                                  unsigned Type) const override;
  33   };
  34 }
  35
  36 PPCELFObjectWriter::PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI)
  37   : MCELFObjectTargetWriter(Is64Bit, OSABI,
  38                             Is64Bit ?  ELF::EM_PPC64 : ELF::EM_PPC,
  39                             /*HasRelocationAddend*/ true) {}
  40
  41 static MCSymbolRefExpr::VariantKind getAccessVariant(const MCValue &Target,
  42                                                      const MCFixup &Fixup) {
  43   const MCExpr *Expr = Fixup.getValue();
  44
  45   if (Expr->getKind() != MCExpr::Target)
  46     return Target.getAccessVariant();
  47
  48   switch (cast<PPCMCExpr>(Expr)->getKind()) {
  49   case PPCMCExpr::VK_PPC_None:
  50     return MCSymbolRefExpr::VK_None;
  51   case PPCMCExpr::VK_PPC_LO:
  52     return MCSymbolRefExpr::VK_PPC_LO;
  53   case PPCMCExpr::VK_PPC_HI:
  54     return MCSymbolRefExpr::VK_PPC_HI;
  55   case PPCMCExpr::VK_PPC_HA:
  56     return MCSymbolRefExpr::VK_PPC_HA;
  57   case PPCMCExpr::VK_PPC_HIGH:
  58     return MCSymbolRefExpr::VK_PPC_HIGH;
  59   case PPCMCExpr::VK_PPC_HIGHA:
  60     return MCSymbolRefExpr::VK_PPC_HIGHA;
  61   case PPCMCExpr::VK_PPC_HIGHERA:
  62     return MCSymbolRefExpr::VK_PPC_HIGHERA;
  63   case PPCMCExpr::VK_PPC_HIGHER:
  64     return MCSymbolRefExpr::VK_PPC_HIGHER;
  65   case PPCMCExpr::VK_PPC_HIGHEST:
  66     return MCSymbolRefExpr::VK_PPC_HIGHEST;
  67   case PPCMCExpr::VK_PPC_HIGHESTA:
  68     return MCSymbolRefExpr::VK_PPC_HIGHESTA;
  69   }
  70   llvm_unreachable("unknown PPCMCExpr kind");
  71 }
  72
  73 unsigned PPCELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
  74                                           const MCFixup &Fixup,
  75                                           bool IsPCRel) const {
  76   MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Target, Fixup);
  77
  78   // determine the type of the relocation
  79   unsigned Type;
  80   if (IsPCRel) {
  81     switch (Fixup.getTargetKind()) {
  82     default:
  83       llvm_unreachable("Unimplemented");
  84     case PPC::fixup_ppc_br24:
  85     case PPC::fixup_ppc_br24abs:
  86       switch (Modifier) {
  87       default: llvm_unreachable("Unsupported Modifier");
  88       case MCSymbolRefExpr::VK_None:
  89         Type = ELF::R_PPC_REL24;
  90         break;
  91       case MCSymbolRefExpr::VK_PLT:
  92         Type = ELF::R_PPC_PLTREL24;
  93         break;
  94       case MCSymbolRefExpr::VK_PPC_LOCAL:
  95         Type = ELF::R_PPC_LOCAL24PC;
  96         break;
  97       }
  98       break;
  99     case PPC::fixup_ppc_brcond14:
 100     case PPC::fixup_ppc_brcond14abs:
 101       Type = ELF::R_PPC_REL14;
 102       break;
 103     case PPC::fixup_ppc_half16:
 104       switch (Modifier) {
 105       default: llvm_unreachable("Unsupported Modifier");
 106       case MCSymbolRefExpr::VK_None:
 107         Type = ELF::R_PPC_REL16;
 108         break;
 109       case MCSymbolRefExpr::VK_PPC_LO:
 110         Type = ELF::R_PPC_REL16_LO;
 111         break;
 112       case MCSymbolRefExpr::VK_PPC_HI:
 113         Type = ELF::R_PPC_REL16_HI;
 114         break;
 115       case MCSymbolRefExpr::VK_PPC_HA:
 116         Type = ELF::R_PPC_REL16_HA;
 117         break;
 118       }
 119       break;
 120     case PPC::fixup_ppc_half16ds:
 121       Target.print(errs());
 122       errs() << '\n';
 123       report_fatal_error("Invalid PC-relative half16ds relocation");
 124     case FK_Data_4:
 125     case FK_PCRel_4:
 126       Type = ELF::R_PPC_REL32;
 127       break;
 128     case FK_Data_8:
 129     case FK_PCRel_8:
 130       Type = ELF::R_PPC64_REL64;
 131       break;
 132     }
 133   } else {
 134     switch (Fixup.getTargetKind()) {
 135       default: llvm_unreachable("invalid fixup kind!");
 136     case FK_NONE:
 137       Type = ELF::R_PPC_NONE;
 138       break;
 139     case PPC::fixup_ppc_br24abs:
 140       Type = ELF::R_PPC_ADDR24;
 141       break;
 142     case PPC::fixup_ppc_brcond14abs:
 143       Type = ELF::R_PPC_ADDR14; // XXX: or BRNTAKEN?_
 144       break;
 145     case PPC::fixup_ppc_half16:
 146       switch (Modifier) {
 147       default: llvm_unreachable("Unsupported Modifier");
 148       case MCSymbolRefExpr::VK_None:
 149         Type = ELF::R_PPC_ADDR16;
 150         break;
 151       case MCSymbolRefExpr::VK_PPC_LO:
 152         Type = ELF::R_PPC_ADDR16_LO;
 153         break;
 154       case MCSymbolRefExpr::VK_PPC_HI:
 155         Type = ELF::R_PPC_ADDR16_HI;
 156         break;
 157       case MCSymbolRefExpr::VK_PPC_HA:
 158         Type = ELF::R_PPC_ADDR16_HA;
 159         break;
 160       case MCSymbolRefExpr::VK_PPC_HIGH:
 161         Type = ELF::R_PPC64_ADDR16_HIGH;
 162         break;
 163       case MCSymbolRefExpr::VK_PPC_HIGHA:
 164         Type = ELF::R_PPC64_ADDR16_HIGHA;
 165         break;
 166       case MCSymbolRefExpr::VK_PPC_HIGHER:
 167         Type = ELF::R_PPC64_ADDR16_HIGHER;
 168         break;
 169       case MCSymbolRefExpr::VK_PPC_HIGHERA:
 170         Type = ELF::R_PPC64_ADDR16_HIGHERA;
 171         break;
 172       case MCSymbolRefExpr::VK_PPC_HIGHEST:
 173         Type = ELF::R_PPC64_ADDR16_HIGHEST;
 174         break;
 175       case MCSymbolRefExpr::VK_PPC_HIGHESTA:
 176         Type = ELF::R_PPC64_ADDR16_HIGHESTA;
 177         break;
 178       case MCSymbolRefExpr::VK_GOT:
 179         Type = ELF::R_PPC_GOT16;
 180         break;
 181       case MCSymbolRefExpr::VK_PPC_GOT_LO:
 182         Type = ELF::R_PPC_GOT16_LO;
 183         break;
 184       case MCSymbolRefExpr::VK_PPC_GOT_HI:
 185         Type = ELF::R_PPC_GOT16_HI;
 186         break;
 187       case MCSymbolRefExpr::VK_PPC_GOT_HA:
 188         Type = ELF::R_PPC_GOT16_HA;
 189         break;
 190       case MCSymbolRefExpr::VK_PPC_TOC:
 191         Type = ELF::R_PPC64_TOC16;
 192         break;
 193       case MCSymbolRefExpr::VK_PPC_TOC_LO:
 194         Type = ELF::R_PPC64_TOC16_LO;
 195         break;
 196       case MCSymbolRefExpr::VK_PPC_TOC_HI:
 197         Type = ELF::R_PPC64_TOC16_HI;
 198         break;
 199       case MCSymbolRefExpr::VK_PPC_TOC_HA:
 200         Type = ELF::R_PPC64_TOC16_HA;
 201         break;
 202       case MCSymbolRefExpr::VK_TPREL:
 203         Type = ELF::R_PPC_TPREL16;
 204         break;
 205       case MCSymbolRefExpr::VK_PPC_TPREL_LO:
 206         Type = ELF::R_PPC_TPREL16_LO;
 207         break;
 208       case MCSymbolRefExpr::VK_PPC_TPREL_HI:
 209         Type = ELF::R_PPC_TPREL16_HI;
 210         break;
 211       case MCSymbolRefExpr::VK_PPC_TPREL_HA:
 212         Type = ELF::R_PPC_TPREL16_HA;
 213         break;
 214       case MCSymbolRefExpr::VK_PPC_TPREL_HIGH:
 215         Type = ELF::R_PPC64_TPREL16_HIGH;
 216         break;
 217       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHA:
 218         Type = ELF::R_PPC64_TPREL16_HIGHA;
 219         break;
 220       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHER:
 221         Type = ELF::R_PPC64_TPREL16_HIGHER;
 222         break;
 223       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHERA:
 224         Type = ELF::R_PPC64_TPREL16_HIGHERA;
 225         break;
 226       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHEST:
 227         Type = ELF::R_PPC64_TPREL16_HIGHEST;
 228         break;
 229       case MCSymbolRefExpr::VK_PPC_TPREL_HIGHESTA:
 230         Type = ELF::R_PPC64_TPREL16_HIGHESTA;
 231         break;
 232       case MCSymbolRefExpr::VK_DTPREL:
 233         Type = ELF::R_PPC64_DTPREL16;
 234         break;
 235       case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
 236         Type = ELF::R_PPC64_DTPREL16_LO;
 237         break;
 238       case MCSymbolRefExpr::VK_PPC_DTPREL_HI:
 239         Type = ELF::R_PPC64_DTPREL16_HI;
 240         break;
 241       case MCSymbolRefExpr::VK_PPC_DTPREL_HA:
 242         Type = ELF::R_PPC64_DTPREL16_HA;
 243         break;
 244       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGH:
 245         Type = ELF::R_PPC64_DTPREL16_HIGH;
 246         break;
 247       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHA:
 248         Type = ELF::R_PPC64_DTPREL16_HIGHA;
 249         break;
 250       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHER:
 251         Type = ELF::R_PPC64_DTPREL16_HIGHER;
 252         break;
 253       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHERA:
 254         Type = ELF::R_PPC64_DTPREL16_HIGHERA;
 255         break;
 256       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHEST:
 257         Type = ELF::R_PPC64_DTPREL16_HIGHEST;
 258         break;
 259       case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHESTA:
 260         Type = ELF::R_PPC64_DTPREL16_HIGHESTA;
 261         break;
 262       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD:
 263         if (is64Bit())
 264           Type = ELF::R_PPC64_GOT_TLSGD16;
 265         else
 266           Type = ELF::R_PPC_GOT_TLSGD16;
 267         break;
 268       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
 269         Type = ELF::R_PPC64_GOT_TLSGD16_LO;
 270         break;
 271       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
 272         Type = ELF::R_PPC64_GOT_TLSGD16_HI;
 273         break;
 274       case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
 275         Type = ELF::R_PPC64_GOT_TLSGD16_HA;
 276         break;
 277       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
 278         if (is64Bit())
 279           Type = ELF::R_PPC64_GOT_TLSLD16;
 280         else
 281           Type = ELF::R_PPC_GOT_TLSLD16;
 282         break;
 283       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
 284         Type = ELF::R_PPC64_GOT_TLSLD16_LO;
 285         break;
 286       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
 287         Type = ELF::R_PPC64_GOT_TLSLD16_HI;
 288         break;
 289       case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
 290         Type = ELF::R_PPC64_GOT_TLSLD16_HA;
 291         break;
 292       case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
 293         /* We don't have R_PPC64_GOT_TPREL16, but since GOT offsets
 294            are always 4-aligned, we can use R_PPC64_GOT_TPREL16_DS.  */
 295         Type = ELF::R_PPC64_GOT_TPREL16_DS;
 296         break;
 297       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
 298         /* We don't have R_PPC64_GOT_TPREL16_LO, but since GOT offsets
 299            are always 4-aligned, we can use R_PPC64_GOT_TPREL16_LO_DS.  */
 300         Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
 301         break;
 302       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HI:
 303         Type = ELF::R_PPC64_GOT_TPREL16_HI;
 304         break;
 305       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
 306         /* We don't have R_PPC64_GOT_DTPREL16, but since GOT offsets
 307            are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_DS.  */
 308         Type = ELF::R_PPC64_GOT_DTPREL16_DS;
 309         break;
 310       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
 311         /* We don't have R_PPC64_GOT_DTPREL16_LO, but since GOT offsets
 312            are always 4-aligned, we can use R_PPC64_GOT_DTPREL16_LO_DS.  */
 313         Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
 314         break;
 315       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA:
 316         Type = ELF::R_PPC64_GOT_TPREL16_HA;
 317         break;
 318       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HI:
 319         Type = ELF::R_PPC64_GOT_DTPREL16_HI;
 320         break;
 321       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HA:
 322         Type = ELF::R_PPC64_GOT_DTPREL16_HA;
 323         break;
 324       }
 325       break;
 326     case PPC::fixup_ppc_half16ds:
 327       switch (Modifier) {
 328       default: llvm_unreachable("Unsupported Modifier");
 329       case MCSymbolRefExpr::VK_None:
 330         Type = ELF::R_PPC64_ADDR16_DS;
 331         break;
 332       case MCSymbolRefExpr::VK_PPC_LO:
 333         Type = ELF::R_PPC64_ADDR16_LO_DS;
 334         break;
 335       case MCSymbolRefExpr::VK_GOT:
 336         Type = ELF::R_PPC64_GOT16_DS;
 337         break;
 338       case MCSymbolRefExpr::VK_PPC_GOT_LO:
 339         Type = ELF::R_PPC64_GOT16_LO_DS;
 340         break;
 341       case MCSymbolRefExpr::VK_PPC_TOC:
 342         Type = ELF::R_PPC64_TOC16_DS;
 343         break;
 344       case MCSymbolRefExpr::VK_PPC_TOC_LO:
 345         Type = ELF::R_PPC64_TOC16_LO_DS;
 346         break;
 347       case MCSymbolRefExpr::VK_TPREL:
 348         Type = ELF::R_PPC64_TPREL16_DS;
 349         break;
 350       case MCSymbolRefExpr::VK_PPC_TPREL_LO:
 351         Type = ELF::R_PPC64_TPREL16_LO_DS;
 352         break;
 353       case MCSymbolRefExpr::VK_DTPREL:
 354         Type = ELF::R_PPC64_DTPREL16_DS;
 355         break;
 356       case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
 357         Type = ELF::R_PPC64_DTPREL16_LO_DS;
 358         break;
 359       case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
 360         Type = ELF::R_PPC64_GOT_TPREL16_DS;
 361         break;
 362       case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
 363         Type = ELF::R_PPC64_GOT_TPREL16_LO_DS;
 364         break;
 365       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
 366         Type = ELF::R_PPC64_GOT_DTPREL16_DS;
 367         break;
 368       case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
 369         Type = ELF::R_PPC64_GOT_DTPREL16_LO_DS;
 370         break;
 371       }
 372       break;
 373     case PPC::fixup_ppc_nofixup:
 374       switch (Modifier) {
 375       default: llvm_unreachable("Unsupported Modifier");
 376       case MCSymbolRefExpr::VK_PPC_TLSGD:
 377         if (is64Bit())
 378           Type = ELF::R_PPC64_TLSGD;
 379         else
 380           Type = ELF::R_PPC_TLSGD;
 381         break;
 382       case MCSymbolRefExpr::VK_PPC_TLSLD:
 383         if (is64Bit())
 384           Type = ELF::R_PPC64_TLSLD;
 385         else
 386           Type = ELF::R_PPC_TLSLD;
 387         break;
 388       case MCSymbolRefExpr::VK_PPC_TLS:
 389         if (is64Bit())
 390           Type = ELF::R_PPC64_TLS;
 391         else
 392           Type = ELF::R_PPC_TLS;
 393         break;
 394       }
 395       break;
 396     case FK_Data_8:
 397       switch (Modifier) {
 398       default: llvm_unreachable("Unsupported Modifier");
 399       case MCSymbolRefExpr::VK_PPC_TOCBASE:
 400         Type = ELF::R_PPC64_TOC;
 401         break;
 402       case MCSymbolRefExpr::VK_None:
 403         Type = ELF::R_PPC64_ADDR64;
 404         break;
 405       case MCSymbolRefExpr::VK_PPC_DTPMOD:
 406         Type = ELF::R_PPC64_DTPMOD64;
 407         break;
 408       case MCSymbolRefExpr::VK_TPREL:
 409         Type = ELF::R_PPC64_TPREL64;
 410         break;
 411       case MCSymbolRefExpr::VK_DTPREL:
 412         Type = ELF::R_PPC64_DTPREL64;
 413         break;
 414       }
 415       break;
 416     case FK_Data_4:
 417       Type = ELF::R_PPC_ADDR32;
 418       break;
 419     case FK_Data_2:
 420       Type = ELF::R_PPC_ADDR16;
 421       break;
 422     }
 423   }
 424   return Type;
 425 }
 426
 427 bool PPCELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
 428                                                  unsigned Type) const {
 429   switch (Type) {
 430     default:
 431       return false;
 432
 433     case ELF::R_PPC_REL24:
 434       // If the target symbol has a local entry point, we must keep the
 435       // target symbol to preserve that information for the linker.
 436       // The "other" values are stored in the last 6 bits of the second byte.
 437       // The traditional defines for STO values assume the full byte and thus
 438       // the shift to pack it.
 439       unsigned Other = cast<MCSymbolELF>(Sym).getOther() << 2;
 440       return (Other & ELF::STO_PPC64_LOCAL_MASK) != 0;
 441   }
 442 }
 443
 444 std::unique_ptr<MCObjectTargetWriter>
 445 llvm::createPPCELFObjectWriter(bool Is64Bit, uint8_t OSABI) {
 446   return std::make_unique<PPCELFObjectWriter>(Is64Bit, OSABI);
 447 }