1 //===-- X86ELFObjectWriter.cpp - X86 ELF Writer ---------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #include "MCTargetDesc/X86FixupKinds.h"
10 #include "MCTargetDesc/X86MCTargetDesc.h"
11 #include "llvm/BinaryFormat/ELF.h"
12 #include "llvm/MC/MCAsmInfo.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCFixup.h"
17 #include "llvm/MC/MCObjectWriter.h"
18 #include "llvm/MC/MCValue.h"
19 #include "llvm/Support/ErrorHandling.h"
27 class X86ELFObjectWriter : public MCELFObjectTargetWriter {
29 X86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine);
30 ~X86ELFObjectWriter() override = default;
33 unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
34 const MCFixup &Fixup, bool IsPCRel) const override;
37 } // end anonymous namespace
39 X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
41 : MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
42 // Only i386 and IAMCU use Rel instead of RelA.
43 /*HasRelocationAddend*/
44 (EMachine != ELF::EM_386) &&
45 (EMachine != ELF::EM_IAMCU)) {}
47 enum X86_64RelType { RT64_NONE, RT64_64, RT64_32, RT64_32S, RT64_16, RT64_8 };
49 static X86_64RelType getType64(unsigned Kind,
50 MCSymbolRefExpr::VariantKind &Modifier,
54 llvm_unreachable("Unimplemented");
57 case X86::reloc_global_offset_table8:
58 Modifier = MCSymbolRefExpr::VK_GOT;
63 case X86::reloc_signed_4byte:
64 case X86::reloc_signed_4byte_relax:
65 if (Modifier == MCSymbolRefExpr::VK_None && !IsPCRel)
68 case X86::reloc_global_offset_table:
69 Modifier = MCSymbolRefExpr::VK_GOT;
74 case X86::reloc_riprel_4byte:
75 case X86::reloc_riprel_4byte_relax:
76 case X86::reloc_riprel_4byte_relax_rex:
77 case X86::reloc_riprel_4byte_movq_load:
79 case X86::reloc_branch_4byte_pcrel:
80 Modifier = MCSymbolRefExpr::VK_PLT;
91 static void checkIs32(MCContext &Ctx, SMLoc Loc, X86_64RelType Type) {
94 "32 bit reloc applied to a field with a different size");
97 static unsigned getRelocType64(MCContext &Ctx, SMLoc Loc,
98 MCSymbolRefExpr::VariantKind Modifier,
99 X86_64RelType Type, bool IsPCRel,
103 llvm_unreachable("Unimplemented");
104 case MCSymbolRefExpr::VK_None:
105 case MCSymbolRefExpr::VK_X86_ABS8:
108 if (Modifier == MCSymbolRefExpr::VK_None)
109 return ELF::R_X86_64_NONE;
110 llvm_unreachable("Unimplemented");
112 return IsPCRel ? ELF::R_X86_64_PC64 : ELF::R_X86_64_64;
114 return IsPCRel ? ELF::R_X86_64_PC32 : ELF::R_X86_64_32;
116 return ELF::R_X86_64_32S;
118 return IsPCRel ? ELF::R_X86_64_PC16 : ELF::R_X86_64_16;
120 return IsPCRel ? ELF::R_X86_64_PC8 : ELF::R_X86_64_8;
122 llvm_unreachable("unexpected relocation type!");
123 case MCSymbolRefExpr::VK_GOT:
126 return IsPCRel ? ELF::R_X86_64_GOTPC64 : ELF::R_X86_64_GOT64;
128 return IsPCRel ? ELF::R_X86_64_GOTPC32 : ELF::R_X86_64_GOT32;
133 llvm_unreachable("Unimplemented");
135 llvm_unreachable("unexpected relocation type!");
136 case MCSymbolRefExpr::VK_GOTOFF:
137 assert(Type == RT64_64);
139 return ELF::R_X86_64_GOTOFF64;
140 case MCSymbolRefExpr::VK_TPOFF:
144 return ELF::R_X86_64_TPOFF64;
146 return ELF::R_X86_64_TPOFF32;
151 llvm_unreachable("Unimplemented");
153 llvm_unreachable("unexpected relocation type!");
154 case MCSymbolRefExpr::VK_DTPOFF:
158 return ELF::R_X86_64_DTPOFF64;
160 return ELF::R_X86_64_DTPOFF32;
165 llvm_unreachable("Unimplemented");
167 llvm_unreachable("unexpected relocation type!");
168 case MCSymbolRefExpr::VK_SIZE:
172 return ELF::R_X86_64_SIZE64;
174 return ELF::R_X86_64_SIZE32;
179 llvm_unreachable("Unimplemented");
181 llvm_unreachable("unexpected relocation type!");
182 case MCSymbolRefExpr::VK_TLSCALL:
183 return ELF::R_X86_64_TLSDESC_CALL;
184 case MCSymbolRefExpr::VK_TLSDESC:
185 return ELF::R_X86_64_GOTPC32_TLSDESC;
186 case MCSymbolRefExpr::VK_TLSGD:
187 checkIs32(Ctx, Loc, Type);
188 return ELF::R_X86_64_TLSGD;
189 case MCSymbolRefExpr::VK_GOTTPOFF:
190 checkIs32(Ctx, Loc, Type);
191 return ELF::R_X86_64_GOTTPOFF;
192 case MCSymbolRefExpr::VK_TLSLD:
193 checkIs32(Ctx, Loc, Type);
194 return ELF::R_X86_64_TLSLD;
195 case MCSymbolRefExpr::VK_PLT:
196 checkIs32(Ctx, Loc, Type);
197 return ELF::R_X86_64_PLT32;
198 case MCSymbolRefExpr::VK_GOTPCREL:
199 checkIs32(Ctx, Loc, Type);
200 // Older versions of ld.bfd/ld.gold/lld
201 // do not support GOTPCRELX/REX_GOTPCRELX,
202 // and we want to keep back-compatibility.
203 if (!Ctx.getAsmInfo()->canRelaxRelocations())
204 return ELF::R_X86_64_GOTPCREL;
207 return ELF::R_X86_64_GOTPCREL;
208 case X86::reloc_riprel_4byte_relax:
209 return ELF::R_X86_64_GOTPCRELX;
210 case X86::reloc_riprel_4byte_relax_rex:
211 case X86::reloc_riprel_4byte_movq_load:
212 return ELF::R_X86_64_REX_GOTPCRELX;
214 llvm_unreachable("unexpected relocation type!");
218 enum X86_32RelType { RT32_NONE, RT32_32, RT32_16, RT32_8 };
220 static X86_32RelType getType32(X86_64RelType T) {
225 llvm_unreachable("Unimplemented");
234 llvm_unreachable("unexpected relocation type!");
237 static unsigned getRelocType32(MCContext &Ctx,
238 MCSymbolRefExpr::VariantKind Modifier,
239 X86_32RelType Type, bool IsPCRel,
243 llvm_unreachable("Unimplemented");
244 case MCSymbolRefExpr::VK_None:
245 case MCSymbolRefExpr::VK_X86_ABS8:
248 if (Modifier == MCSymbolRefExpr::VK_None)
249 return ELF::R_386_NONE;
250 llvm_unreachable("Unimplemented");
252 return IsPCRel ? ELF::R_386_PC32 : ELF::R_386_32;
254 return IsPCRel ? ELF::R_386_PC16 : ELF::R_386_16;
256 return IsPCRel ? ELF::R_386_PC8 : ELF::R_386_8;
258 llvm_unreachable("unexpected relocation type!");
259 case MCSymbolRefExpr::VK_GOT:
260 assert(Type == RT32_32);
262 return ELF::R_386_GOTPC;
263 // Older versions of ld.bfd/ld.gold/lld do not support R_386_GOT32X and we
264 // want to maintain compatibility.
265 if (!Ctx.getAsmInfo()->canRelaxRelocations())
266 return ELF::R_386_GOT32;
268 return Kind == X86::reloc_signed_4byte_relax ? ELF::R_386_GOT32X
270 case MCSymbolRefExpr::VK_GOTOFF:
271 assert(Type == RT32_32);
273 return ELF::R_386_GOTOFF;
274 case MCSymbolRefExpr::VK_TLSCALL:
275 return ELF::R_386_TLS_DESC_CALL;
276 case MCSymbolRefExpr::VK_TLSDESC:
277 return ELF::R_386_TLS_GOTDESC;
278 case MCSymbolRefExpr::VK_TPOFF:
279 assert(Type == RT32_32);
281 return ELF::R_386_TLS_LE_32;
282 case MCSymbolRefExpr::VK_DTPOFF:
283 assert(Type == RT32_32);
285 return ELF::R_386_TLS_LDO_32;
286 case MCSymbolRefExpr::VK_TLSGD:
287 assert(Type == RT32_32);
289 return ELF::R_386_TLS_GD;
290 case MCSymbolRefExpr::VK_GOTTPOFF:
291 assert(Type == RT32_32);
293 return ELF::R_386_TLS_IE_32;
294 case MCSymbolRefExpr::VK_PLT:
295 assert(Type == RT32_32);
296 return ELF::R_386_PLT32;
297 case MCSymbolRefExpr::VK_INDNTPOFF:
298 assert(Type == RT32_32);
300 return ELF::R_386_TLS_IE;
301 case MCSymbolRefExpr::VK_NTPOFF:
302 assert(Type == RT32_32);
304 return ELF::R_386_TLS_LE;
305 case MCSymbolRefExpr::VK_GOTNTPOFF:
306 assert(Type == RT32_32);
308 return ELF::R_386_TLS_GOTIE;
309 case MCSymbolRefExpr::VK_TLSLDM:
310 assert(Type == RT32_32);
312 return ELF::R_386_TLS_LDM;
316 unsigned X86ELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
317 const MCFixup &Fixup,
318 bool IsPCRel) const {
319 MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
320 unsigned Kind = Fixup.getKind();
321 X86_64RelType Type = getType64(Kind, Modifier, IsPCRel);
322 if (getEMachine() == ELF::EM_X86_64)
323 return getRelocType64(Ctx, Fixup.getLoc(), Modifier, Type, IsPCRel, Kind);
325 assert((getEMachine() == ELF::EM_386 || getEMachine() == ELF::EM_IAMCU) &&
326 "Unsupported ELF machine type.");
327 return getRelocType32(Ctx, Modifier, getType32(Type), IsPCRel, Kind);
330 std::unique_ptr<MCObjectTargetWriter>
331 llvm::createX86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine) {
332 return llvm::make_unique<X86ELFObjectWriter>(IsELF64, OSABI, EMachine);