xref: /llvm-project-15.0.7/lld/ELF/Target.cpp (revision d72ece64)
1 //===- Target.cpp ---------------------------------------------------------===//
2 //
3 //                             The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Machine-specific things, such as applying relocations, creation of
11 // GOT or PLT entries, etc., are handled in this file.
12 //
13 // Refer the ELF spec for the single letter variables, S, A or P, used
14 // in this file.
15 //
16 // Some functions defined in this file has "relaxTls" as part of their names.
17 // They do peephole optimization for TLS variables by rewriting instructions.
18 // They are not part of the ABI but optional optimization, so you can skip
19 // them if you are not interested in how TLS variables are optimized.
20 // See the following paper for the details.
21 //
22 //   Ulrich Drepper, ELF Handling For Thread-Local Storage
23 //   http://www.akkadia.org/drepper/tls.pdf
24 //
25 //===----------------------------------------------------------------------===//
26 
27 #include "Target.h"
28 #include "Error.h"
29 #include "InputFiles.h"
30 #include "OutputSections.h"
31 #include "Symbols.h"
32 #include "SyntheticSections.h"
33 #include "Thunks.h"
34 #include "Writer.h"
35 
36 #include "llvm/ADT/ArrayRef.h"
37 #include "llvm/Object/ELF.h"
38 #include "llvm/Support/Endian.h"
39 #include "llvm/Support/ELF.h"
40 
41 using namespace llvm;
42 using namespace llvm::object;
43 using namespace llvm::support::endian;
44 using namespace llvm::ELF;
45 
46 namespace lld {
47 namespace elf {
48 
49 TargetInfo *Target;
50 
51 static void or32le(uint8_t *P, int32_t V) { write32le(P, read32le(P) | V); }
52 static void or32be(uint8_t *P, int32_t V) { write32be(P, read32be(P) | V); }
53 
54 std::string toString(uint32_t Type) {
55   return getELFRelocationTypeName(Config->EMachine, Type);
56 }
57 
58 template <unsigned N> static void checkInt(int64_t V, uint32_t Type) {
59   if (!isInt<N>(V))
60     error("relocation " + toString(Type) + " out of range");
61 }
62 
63 template <unsigned N> static void checkUInt(uint64_t V, uint32_t Type) {
64   if (!isUInt<N>(V))
65     error("relocation " + toString(Type) + " out of range");
66 }
67 
68 template <unsigned N> static void checkIntUInt(uint64_t V, uint32_t Type) {
69   if (!isInt<N>(V) && !isUInt<N>(V))
70     error("relocation " + toString(Type) + " out of range");
71 }
72 
73 template <unsigned N> static void checkAlignment(uint64_t V, uint32_t Type) {
74   if ((V & (N - 1)) != 0)
75     error("improper alignment for relocation " + toString(Type));
76 }
77 
78 static void errorDynRel(uint32_t Type) {
79   error("relocation " + toString(Type) +
80         " cannot be used against shared object; recompile with -fPIC.");
81 }
82 
83 namespace {
84 class X86TargetInfo final : public TargetInfo {
85 public:
86   X86TargetInfo();
87   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
88   uint64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
89   void writeGotPltHeader(uint8_t *Buf) const override;
90   uint32_t getDynRel(uint32_t Type) const override;
91   bool isTlsLocalDynamicRel(uint32_t Type) const override;
92   bool isTlsGlobalDynamicRel(uint32_t Type) const override;
93   bool isTlsInitialExecRel(uint32_t Type) const override;
94   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
95   void writePltHeader(uint8_t *Buf) const override;
96   void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
97                 int32_t Index, unsigned RelOff) const override;
98   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
99 
100   RelExpr adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
101                           RelExpr Expr) const override;
102   void relaxTlsGdToIe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
103   void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
104   void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
105   void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
106 };
107 
108 template <class ELFT> class X86_64TargetInfo final : public TargetInfo {
109 public:
110   X86_64TargetInfo();
111   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
112   uint32_t getDynRel(uint32_t Type) const override;
113   bool isTlsLocalDynamicRel(uint32_t Type) const override;
114   bool isTlsGlobalDynamicRel(uint32_t Type) const override;
115   bool isTlsInitialExecRel(uint32_t Type) const override;
116   void writeGotPltHeader(uint8_t *Buf) const override;
117   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
118   void writePltHeader(uint8_t *Buf) const override;
119   void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
120                 int32_t Index, unsigned RelOff) const override;
121   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
122 
123   RelExpr adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
124                           RelExpr Expr) const override;
125   void relaxGot(uint8_t *Loc, uint64_t Val) const override;
126   void relaxTlsGdToIe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
127   void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
128   void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
129   void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
130 
131 private:
132   void relaxGotNoPic(uint8_t *Loc, uint64_t Val, uint8_t Op,
133                      uint8_t ModRm) const;
134 };
135 
136 class PPCTargetInfo final : public TargetInfo {
137 public:
138   PPCTargetInfo();
139   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
140   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
141 };
142 
143 class PPC64TargetInfo final : public TargetInfo {
144 public:
145   PPC64TargetInfo();
146   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
147   void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
148                 int32_t Index, unsigned RelOff) const override;
149   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
150 };
151 
152 class AArch64TargetInfo final : public TargetInfo {
153 public:
154   AArch64TargetInfo();
155   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
156   uint32_t getDynRel(uint32_t Type) const override;
157   bool isTlsInitialExecRel(uint32_t Type) const override;
158   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
159   void writePltHeader(uint8_t *Buf) const override;
160   void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
161                 int32_t Index, unsigned RelOff) const override;
162   bool usesOnlyLowPageBits(uint32_t Type) const override;
163   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
164   RelExpr adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
165                           RelExpr Expr) const override;
166   void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
167   void relaxTlsGdToIe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
168   void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
169 };
170 
171 class AMDGPUTargetInfo final : public TargetInfo {
172 public:
173   AMDGPUTargetInfo();
174   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
175   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
176 };
177 
178 class ARMTargetInfo final : public TargetInfo {
179 public:
180   ARMTargetInfo();
181   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
182   uint32_t getDynRel(uint32_t Type) const override;
183   uint64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
184   bool isTlsLocalDynamicRel(uint32_t Type) const override;
185   bool isTlsGlobalDynamicRel(uint32_t Type) const override;
186   bool isTlsInitialExecRel(uint32_t Type) const override;
187   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
188   void writePltHeader(uint8_t *Buf) const override;
189   void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
190                 int32_t Index, unsigned RelOff) const override;
191   RelExpr getThunkExpr(RelExpr Expr, uint32_t RelocType, const InputFile &File,
192                        const SymbolBody &S) const override;
193   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
194 };
195 
196 template <class ELFT> class MipsTargetInfo final : public TargetInfo {
197 public:
198   MipsTargetInfo();
199   RelExpr getRelExpr(uint32_t Type, const SymbolBody &S) const override;
200   uint64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const override;
201   uint32_t getDynRel(uint32_t Type) const override;
202   bool isTlsLocalDynamicRel(uint32_t Type) const override;
203   bool isTlsGlobalDynamicRel(uint32_t Type) const override;
204   void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const override;
205   void writePltHeader(uint8_t *Buf) const override;
206   void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
207                 int32_t Index, unsigned RelOff) const override;
208   RelExpr getThunkExpr(RelExpr Expr, uint32_t RelocType, const InputFile &File,
209                        const SymbolBody &S) const override;
210   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
211   bool usesOnlyLowPageBits(uint32_t Type) const override;
212 };
213 } // anonymous namespace
214 
215 TargetInfo *createTarget() {
216   switch (Config->EMachine) {
217   case EM_386:
218   case EM_IAMCU:
219     return new X86TargetInfo();
220   case EM_AARCH64:
221     return new AArch64TargetInfo();
222   case EM_AMDGPU:
223     return new AMDGPUTargetInfo();
224   case EM_ARM:
225     return new ARMTargetInfo();
226   case EM_MIPS:
227     switch (Config->EKind) {
228     case ELF32LEKind:
229       return new MipsTargetInfo<ELF32LE>();
230     case ELF32BEKind:
231       return new MipsTargetInfo<ELF32BE>();
232     case ELF64LEKind:
233       return new MipsTargetInfo<ELF64LE>();
234     case ELF64BEKind:
235       return new MipsTargetInfo<ELF64BE>();
236     default:
237       fatal("unsupported MIPS target");
238     }
239   case EM_PPC:
240     return new PPCTargetInfo();
241   case EM_PPC64:
242     return new PPC64TargetInfo();
243   case EM_X86_64:
244     if (Config->EKind == ELF32LEKind)
245       return new X86_64TargetInfo<ELF32LE>();
246     return new X86_64TargetInfo<ELF64LE>();
247   }
248   fatal("unknown target machine");
249 }
250 
251 TargetInfo::~TargetInfo() {}
252 
253 uint64_t TargetInfo::getImplicitAddend(const uint8_t *Buf,
254                                        uint32_t Type) const {
255   return 0;
256 }
257 
258 bool TargetInfo::usesOnlyLowPageBits(uint32_t Type) const { return false; }
259 
260 RelExpr TargetInfo::getThunkExpr(RelExpr Expr, uint32_t RelocType,
261                                  const InputFile &File,
262                                  const SymbolBody &S) const {
263   return Expr;
264 }
265 
266 bool TargetInfo::isTlsInitialExecRel(uint32_t Type) const { return false; }
267 
268 bool TargetInfo::isTlsLocalDynamicRel(uint32_t Type) const { return false; }
269 
270 bool TargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const { return false; }
271 
272 RelExpr TargetInfo::adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
273                                     RelExpr Expr) const {
274   return Expr;
275 }
276 
277 void TargetInfo::relaxGot(uint8_t *Loc, uint64_t Val) const {
278   llvm_unreachable("Should not have claimed to be relaxable");
279 }
280 
281 void TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
282                                 uint64_t Val) const {
283   llvm_unreachable("Should not have claimed to be relaxable");
284 }
285 
286 void TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
287                                 uint64_t Val) const {
288   llvm_unreachable("Should not have claimed to be relaxable");
289 }
290 
291 void TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
292                                 uint64_t Val) const {
293   llvm_unreachable("Should not have claimed to be relaxable");
294 }
295 
296 void TargetInfo::relaxTlsLdToLe(uint8_t *Loc, uint32_t Type,
297                                 uint64_t Val) const {
298   llvm_unreachable("Should not have claimed to be relaxable");
299 }
300 
301 X86TargetInfo::X86TargetInfo() {
302   CopyRel = R_386_COPY;
303   GotRel = R_386_GLOB_DAT;
304   PltRel = R_386_JUMP_SLOT;
305   IRelativeRel = R_386_IRELATIVE;
306   RelativeRel = R_386_RELATIVE;
307   TlsGotRel = R_386_TLS_TPOFF;
308   TlsModuleIndexRel = R_386_TLS_DTPMOD32;
309   TlsOffsetRel = R_386_TLS_DTPOFF32;
310   GotEntrySize = 4;
311   GotPltEntrySize = 4;
312   PltEntrySize = 16;
313   PltHeaderSize = 16;
314   TlsGdRelaxSkip = 2;
315 }
316 
317 RelExpr X86TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
318   switch (Type) {
319   default:
320     return R_ABS;
321   case R_386_TLS_GD:
322     return R_TLSGD;
323   case R_386_TLS_LDM:
324     return R_TLSLD;
325   case R_386_PLT32:
326     return R_PLT_PC;
327   case R_386_PC32:
328     return R_PC;
329   case R_386_GOTPC:
330     return R_GOTONLY_PC_FROM_END;
331   case R_386_TLS_IE:
332     return R_GOT;
333   case R_386_GOT32:
334   case R_386_GOT32X:
335   case R_386_TLS_GOTIE:
336     return R_GOT_FROM_END;
337   case R_386_GOTOFF:
338     return R_GOTREL_FROM_END;
339   case R_386_TLS_LE:
340     return R_TLS;
341   case R_386_TLS_LE_32:
342     return R_NEG_TLS;
343   }
344 }
345 
346 RelExpr X86TargetInfo::adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
347                                        RelExpr Expr) const {
348   switch (Expr) {
349   default:
350     return Expr;
351   case R_RELAX_TLS_GD_TO_IE:
352     return R_RELAX_TLS_GD_TO_IE_END;
353   case R_RELAX_TLS_GD_TO_LE:
354     return R_RELAX_TLS_GD_TO_LE_NEG;
355   }
356 }
357 
358 void X86TargetInfo::writeGotPltHeader(uint8_t *Buf) const {
359   write32le(Buf, In<ELF32LE>::Dynamic->getVA());
360 }
361 
362 void X86TargetInfo::writeGotPlt(uint8_t *Buf, const SymbolBody &S) const {
363   // Entries in .got.plt initially points back to the corresponding
364   // PLT entries with a fixed offset to skip the first instruction.
365   write32le(Buf, S.getPltVA<ELF32LE>() + 6);
366 }
367 
368 uint32_t X86TargetInfo::getDynRel(uint32_t Type) const {
369   if (Type == R_386_TLS_LE)
370     return R_386_TLS_TPOFF;
371   if (Type == R_386_TLS_LE_32)
372     return R_386_TLS_TPOFF32;
373   return Type;
374 }
375 
376 bool X86TargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const {
377   return Type == R_386_TLS_GD;
378 }
379 
380 bool X86TargetInfo::isTlsLocalDynamicRel(uint32_t Type) const {
381   return Type == R_386_TLS_LDO_32 || Type == R_386_TLS_LDM;
382 }
383 
384 bool X86TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
385   return Type == R_386_TLS_IE || Type == R_386_TLS_GOTIE;
386 }
387 
388 void X86TargetInfo::writePltHeader(uint8_t *Buf) const {
389   // Executable files and shared object files have
390   // separate procedure linkage tables.
391   if (Config->Pic) {
392     const uint8_t V[] = {
393         0xff, 0xb3, 0x04, 0x00, 0x00, 0x00, // pushl 4(%ebx)
394         0xff, 0xa3, 0x08, 0x00, 0x00, 0x00, // jmp   *8(%ebx)
395         0x90, 0x90, 0x90, 0x90              // nop; nop; nop; nop
396     };
397     memcpy(Buf, V, sizeof(V));
398     return;
399   }
400 
401   const uint8_t PltData[] = {
402       0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushl (GOT+4)
403       0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp   *(GOT+8)
404       0x90, 0x90, 0x90, 0x90              // nop; nop; nop; nop
405   };
406   memcpy(Buf, PltData, sizeof(PltData));
407   uint32_t Got = In<ELF32LE>::GotPlt->getVA();
408   write32le(Buf + 2, Got + 4);
409   write32le(Buf + 8, Got + 8);
410 }
411 
412 void X86TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
413                              uint64_t PltEntryAddr, int32_t Index,
414                              unsigned RelOff) const {
415   const uint8_t Inst[] = {
416       0xff, 0x00, 0x00, 0x00, 0x00, 0x00, // jmp *foo_in_GOT|*foo@GOT(%ebx)
417       0x68, 0x00, 0x00, 0x00, 0x00,       // pushl $reloc_offset
418       0xe9, 0x00, 0x00, 0x00, 0x00        // jmp .PLT0@PC
419   };
420   memcpy(Buf, Inst, sizeof(Inst));
421 
422   // jmp *foo@GOT(%ebx) or jmp *foo_in_GOT
423   Buf[1] = Config->Pic ? 0xa3 : 0x25;
424   uint32_t Got = In<ELF32LE>::GotPlt->getVA();
425   write32le(Buf + 2, Config->Shared ? GotEntryAddr - Got : GotEntryAddr);
426   write32le(Buf + 7, RelOff);
427   write32le(Buf + 12, -Index * PltEntrySize - PltHeaderSize - 16);
428 }
429 
430 uint64_t X86TargetInfo::getImplicitAddend(const uint8_t *Buf,
431                                           uint32_t Type) const {
432   switch (Type) {
433   default:
434     return 0;
435   case R_386_32:
436   case R_386_GOT32:
437   case R_386_GOT32X:
438   case R_386_GOTOFF:
439   case R_386_GOTPC:
440   case R_386_PC32:
441   case R_386_PLT32:
442   case R_386_TLS_LE:
443     return read32le(Buf);
444   }
445 }
446 
447 void X86TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
448                                 uint64_t Val) const {
449   checkInt<32>(Val, Type);
450   write32le(Loc, Val);
451 }
452 
453 void X86TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
454                                    uint64_t Val) const {
455   // Convert
456   //   leal x@tlsgd(, %ebx, 1),
457   //   call __tls_get_addr@plt
458   // to
459   //   movl %gs:0,%eax
460   //   subl $x@ntpoff,%eax
461   const uint8_t Inst[] = {
462       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, // movl %gs:0, %eax
463       0x81, 0xe8, 0x00, 0x00, 0x00, 0x00  // subl 0(%ebx), %eax
464   };
465   memcpy(Loc - 3, Inst, sizeof(Inst));
466   relocateOne(Loc + 5, R_386_32, Val);
467 }
468 
469 void X86TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
470                                    uint64_t Val) const {
471   // Convert
472   //   leal x@tlsgd(, %ebx, 1),
473   //   call __tls_get_addr@plt
474   // to
475   //   movl %gs:0, %eax
476   //   addl x@gotntpoff(%ebx), %eax
477   const uint8_t Inst[] = {
478       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, // movl %gs:0, %eax
479       0x03, 0x83, 0x00, 0x00, 0x00, 0x00  // addl 0(%ebx), %eax
480   };
481   memcpy(Loc - 3, Inst, sizeof(Inst));
482   relocateOne(Loc + 5, R_386_32, Val);
483 }
484 
485 // In some conditions, relocations can be optimized to avoid using GOT.
486 // This function does that for Initial Exec to Local Exec case.
487 void X86TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
488                                    uint64_t Val) const {
489   // Ulrich's document section 6.2 says that @gotntpoff can
490   // be used with MOVL or ADDL instructions.
491   // @indntpoff is similar to @gotntpoff, but for use in
492   // position dependent code.
493   uint8_t Reg = (Loc[-1] >> 3) & 7;
494 
495   if (Type == R_386_TLS_IE) {
496     if (Loc[-1] == 0xa1) {
497       // "movl foo@indntpoff,%eax" -> "movl $foo,%eax"
498       // This case is different from the generic case below because
499       // this is a 5 byte instruction while below is 6 bytes.
500       Loc[-1] = 0xb8;
501     } else if (Loc[-2] == 0x8b) {
502       // "movl foo@indntpoff,%reg" -> "movl $foo,%reg"
503       Loc[-2] = 0xc7;
504       Loc[-1] = 0xc0 | Reg;
505     } else {
506       // "addl foo@indntpoff,%reg" -> "addl $foo,%reg"
507       Loc[-2] = 0x81;
508       Loc[-1] = 0xc0 | Reg;
509     }
510   } else {
511     assert(Type == R_386_TLS_GOTIE);
512     if (Loc[-2] == 0x8b) {
513       // "movl foo@gottpoff(%rip),%reg" -> "movl $foo,%reg"
514       Loc[-2] = 0xc7;
515       Loc[-1] = 0xc0 | Reg;
516     } else {
517       // "addl foo@gotntpoff(%rip),%reg" -> "leal foo(%reg),%reg"
518       Loc[-2] = 0x8d;
519       Loc[-1] = 0x80 | (Reg << 3) | Reg;
520     }
521   }
522   relocateOne(Loc, R_386_TLS_LE, Val);
523 }
524 
525 void X86TargetInfo::relaxTlsLdToLe(uint8_t *Loc, uint32_t Type,
526                                    uint64_t Val) const {
527   if (Type == R_386_TLS_LDO_32) {
528     relocateOne(Loc, R_386_TLS_LE, Val);
529     return;
530   }
531 
532   // Convert
533   //   leal foo(%reg),%eax
534   //   call ___tls_get_addr
535   // to
536   //   movl %gs:0,%eax
537   //   nop
538   //   leal 0(%esi,1),%esi
539   const uint8_t Inst[] = {
540       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, // movl %gs:0,%eax
541       0x90,                               // nop
542       0x8d, 0x74, 0x26, 0x00              // leal 0(%esi,1),%esi
543   };
544   memcpy(Loc - 2, Inst, sizeof(Inst));
545 }
546 
547 template <class ELFT> X86_64TargetInfo<ELFT>::X86_64TargetInfo() {
548   CopyRel = R_X86_64_COPY;
549   GotRel = R_X86_64_GLOB_DAT;
550   PltRel = R_X86_64_JUMP_SLOT;
551   RelativeRel = R_X86_64_RELATIVE;
552   IRelativeRel = R_X86_64_IRELATIVE;
553   TlsGotRel = R_X86_64_TPOFF64;
554   TlsModuleIndexRel = R_X86_64_DTPMOD64;
555   TlsOffsetRel = R_X86_64_DTPOFF64;
556   GotEntrySize = 8;
557   GotPltEntrySize = 8;
558   PltEntrySize = 16;
559   PltHeaderSize = 16;
560   TlsGdRelaxSkip = 2;
561   // Align to the large page size (known as a superpage or huge page).
562   // FreeBSD automatically promotes large, superpage-aligned allocations.
563   DefaultImageBase = 0x200000;
564 }
565 
566 template <class ELFT>
567 RelExpr X86_64TargetInfo<ELFT>::getRelExpr(uint32_t Type,
568                                            const SymbolBody &S) const {
569   switch (Type) {
570   default:
571     return R_ABS;
572   case R_X86_64_TPOFF32:
573     return R_TLS;
574   case R_X86_64_TLSLD:
575     return R_TLSLD_PC;
576   case R_X86_64_TLSGD:
577     return R_TLSGD_PC;
578   case R_X86_64_SIZE32:
579   case R_X86_64_SIZE64:
580     return R_SIZE;
581   case R_X86_64_PLT32:
582     return R_PLT_PC;
583   case R_X86_64_PC32:
584   case R_X86_64_PC64:
585     return R_PC;
586   case R_X86_64_GOT32:
587     return R_GOT_FROM_END;
588   case R_X86_64_GOTPCREL:
589   case R_X86_64_GOTPCRELX:
590   case R_X86_64_REX_GOTPCRELX:
591   case R_X86_64_GOTTPOFF:
592     return R_GOT_PC;
593   }
594 }
595 
596 template <class ELFT>
597 void X86_64TargetInfo<ELFT>::writeGotPltHeader(uint8_t *Buf) const {
598   // The first entry holds the value of _DYNAMIC. It is not clear why that is
599   // required, but it is documented in the psabi and the glibc dynamic linker
600   // seems to use it (note that this is relevant for linking ld.so, not any
601   // other program).
602   write64le(Buf, In<ELFT>::Dynamic->getVA());
603 }
604 
605 template <class ELFT>
606 void X86_64TargetInfo<ELFT>::writeGotPlt(uint8_t *Buf,
607                                          const SymbolBody &S) const {
608   // See comments in X86TargetInfo::writeGotPlt.
609   write32le(Buf, S.getPltVA<ELFT>() + 6);
610 }
611 
612 template <class ELFT>
613 void X86_64TargetInfo<ELFT>::writePltHeader(uint8_t *Buf) const {
614   const uint8_t PltData[] = {
615       0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushq GOT+8(%rip)
616       0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *GOT+16(%rip)
617       0x0f, 0x1f, 0x40, 0x00              // nopl 0x0(rax)
618   };
619   memcpy(Buf, PltData, sizeof(PltData));
620   uint64_t Got = In<ELFT>::GotPlt->getVA();
621   uint64_t Plt = In<ELFT>::Plt->getVA();
622   write32le(Buf + 2, Got - Plt + 2); // GOT+8
623   write32le(Buf + 8, Got - Plt + 4); // GOT+16
624 }
625 
626 template <class ELFT>
627 void X86_64TargetInfo<ELFT>::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
628                                       uint64_t PltEntryAddr, int32_t Index,
629                                       unsigned RelOff) const {
630   const uint8_t Inst[] = {
631       0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmpq *got(%rip)
632       0x68, 0x00, 0x00, 0x00, 0x00,       // pushq <relocation index>
633       0xe9, 0x00, 0x00, 0x00, 0x00        // jmpq plt[0]
634   };
635   memcpy(Buf, Inst, sizeof(Inst));
636 
637   write32le(Buf + 2, GotEntryAddr - PltEntryAddr - 6);
638   write32le(Buf + 7, Index);
639   write32le(Buf + 12, -Index * PltEntrySize - PltHeaderSize - 16);
640 }
641 
642 template <class ELFT>
643 uint32_t X86_64TargetInfo<ELFT>::getDynRel(uint32_t Type) const {
644   if (Type == R_X86_64_PC32 || Type == R_X86_64_32)
645     errorDynRel(Type);
646   return Type;
647 }
648 
649 template <class ELFT>
650 bool X86_64TargetInfo<ELFT>::isTlsInitialExecRel(uint32_t Type) const {
651   return Type == R_X86_64_GOTTPOFF;
652 }
653 
654 template <class ELFT>
655 bool X86_64TargetInfo<ELFT>::isTlsGlobalDynamicRel(uint32_t Type) const {
656   return Type == R_X86_64_TLSGD;
657 }
658 
659 template <class ELFT>
660 bool X86_64TargetInfo<ELFT>::isTlsLocalDynamicRel(uint32_t Type) const {
661   return Type == R_X86_64_DTPOFF32 || Type == R_X86_64_DTPOFF64 ||
662          Type == R_X86_64_TLSLD;
663 }
664 
665 template <class ELFT>
666 void X86_64TargetInfo<ELFT>::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
667                                             uint64_t Val) const {
668   // Convert
669   //   .byte 0x66
670   //   leaq x@tlsgd(%rip), %rdi
671   //   .word 0x6666
672   //   rex64
673   //   call __tls_get_addr@plt
674   // to
675   //   mov %fs:0x0,%rax
676   //   lea x@tpoff,%rax
677   const uint8_t Inst[] = {
678       0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00, // mov %fs:0x0,%rax
679       0x48, 0x8d, 0x80, 0x00, 0x00, 0x00, 0x00              // lea x@tpoff,%rax
680   };
681   memcpy(Loc - 4, Inst, sizeof(Inst));
682   // The original code used a pc relative relocation and so we have to
683   // compensate for the -4 in had in the addend.
684   relocateOne(Loc + 8, R_X86_64_TPOFF32, Val + 4);
685 }
686 
687 template <class ELFT>
688 void X86_64TargetInfo<ELFT>::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
689                                             uint64_t Val) const {
690   // Convert
691   //   .byte 0x66
692   //   leaq x@tlsgd(%rip), %rdi
693   //   .word 0x6666
694   //   rex64
695   //   call __tls_get_addr@plt
696   // to
697   //   mov %fs:0x0,%rax
698   //   addq x@tpoff,%rax
699   const uint8_t Inst[] = {
700       0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00, // mov %fs:0x0,%rax
701       0x48, 0x03, 0x05, 0x00, 0x00, 0x00, 0x00              // addq x@tpoff,%rax
702   };
703   memcpy(Loc - 4, Inst, sizeof(Inst));
704   // Both code sequences are PC relatives, but since we are moving the constant
705   // forward by 8 bytes we have to subtract the value by 8.
706   relocateOne(Loc + 8, R_X86_64_PC32, Val - 8);
707 }
708 
709 // In some conditions, R_X86_64_GOTTPOFF relocation can be optimized to
710 // R_X86_64_TPOFF32 so that it does not use GOT.
711 template <class ELFT>
712 void X86_64TargetInfo<ELFT>::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
713                                             uint64_t Val) const {
714   uint8_t *Inst = Loc - 3;
715   uint8_t Reg = Loc[-1] >> 3;
716   uint8_t *RegSlot = Loc - 1;
717 
718   // Note that ADD with RSP or R12 is converted to ADD instead of LEA
719   // because LEA with these registers needs 4 bytes to encode and thus
720   // wouldn't fit the space.
721 
722   if (memcmp(Inst, "\x48\x03\x25", 3) == 0) {
723     // "addq foo@gottpoff(%rip),%rsp" -> "addq $foo,%rsp"
724     memcpy(Inst, "\x48\x81\xc4", 3);
725   } else if (memcmp(Inst, "\x4c\x03\x25", 3) == 0) {
726     // "addq foo@gottpoff(%rip),%r12" -> "addq $foo,%r12"
727     memcpy(Inst, "\x49\x81\xc4", 3);
728   } else if (memcmp(Inst, "\x4c\x03", 2) == 0) {
729     // "addq foo@gottpoff(%rip),%r[8-15]" -> "leaq foo(%r[8-15]),%r[8-15]"
730     memcpy(Inst, "\x4d\x8d", 2);
731     *RegSlot = 0x80 | (Reg << 3) | Reg;
732   } else if (memcmp(Inst, "\x48\x03", 2) == 0) {
733     // "addq foo@gottpoff(%rip),%reg -> "leaq foo(%reg),%reg"
734     memcpy(Inst, "\x48\x8d", 2);
735     *RegSlot = 0x80 | (Reg << 3) | Reg;
736   } else if (memcmp(Inst, "\x4c\x8b", 2) == 0) {
737     // "movq foo@gottpoff(%rip),%r[8-15]" -> "movq $foo,%r[8-15]"
738     memcpy(Inst, "\x49\xc7", 2);
739     *RegSlot = 0xc0 | Reg;
740   } else if (memcmp(Inst, "\x48\x8b", 2) == 0) {
741     // "movq foo@gottpoff(%rip),%reg" -> "movq $foo,%reg"
742     memcpy(Inst, "\x48\xc7", 2);
743     *RegSlot = 0xc0 | Reg;
744   } else {
745     fatal("R_X86_64_GOTTPOFF must be used in MOVQ or ADDQ instructions only");
746   }
747 
748   // The original code used a PC relative relocation.
749   // Need to compensate for the -4 it had in the addend.
750   relocateOne(Loc, R_X86_64_TPOFF32, Val + 4);
751 }
752 
753 template <class ELFT>
754 void X86_64TargetInfo<ELFT>::relaxTlsLdToLe(uint8_t *Loc, uint32_t Type,
755                                             uint64_t Val) const {
756   // Convert
757   //   leaq bar@tlsld(%rip), %rdi
758   //   callq __tls_get_addr@PLT
759   //   leaq bar@dtpoff(%rax), %rcx
760   // to
761   //   .word 0x6666
762   //   .byte 0x66
763   //   mov %fs:0,%rax
764   //   leaq bar@tpoff(%rax), %rcx
765   if (Type == R_X86_64_DTPOFF64) {
766     write64le(Loc, Val);
767     return;
768   }
769   if (Type == R_X86_64_DTPOFF32) {
770     relocateOne(Loc, R_X86_64_TPOFF32, Val);
771     return;
772   }
773 
774   const uint8_t Inst[] = {
775       0x66, 0x66,                                          // .word 0x6666
776       0x66,                                                // .byte 0x66
777       0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00 // mov %fs:0,%rax
778   };
779   memcpy(Loc - 3, Inst, sizeof(Inst));
780 }
781 
782 template <class ELFT>
783 void X86_64TargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint32_t Type,
784                                          uint64_t Val) const {
785   switch (Type) {
786   case R_X86_64_32:
787     checkUInt<32>(Val, Type);
788     write32le(Loc, Val);
789     break;
790   case R_X86_64_32S:
791   case R_X86_64_TPOFF32:
792   case R_X86_64_GOT32:
793   case R_X86_64_GOTPCREL:
794   case R_X86_64_GOTPCRELX:
795   case R_X86_64_REX_GOTPCRELX:
796   case R_X86_64_PC32:
797   case R_X86_64_GOTTPOFF:
798   case R_X86_64_PLT32:
799   case R_X86_64_TLSGD:
800   case R_X86_64_TLSLD:
801   case R_X86_64_DTPOFF32:
802   case R_X86_64_SIZE32:
803     checkInt<32>(Val, Type);
804     write32le(Loc, Val);
805     break;
806   case R_X86_64_64:
807   case R_X86_64_DTPOFF64:
808   case R_X86_64_SIZE64:
809   case R_X86_64_PC64:
810     write64le(Loc, Val);
811     break;
812   default:
813     fatal("unrecognized reloc " + Twine(Type));
814   }
815 }
816 
817 template <class ELFT>
818 RelExpr X86_64TargetInfo<ELFT>::adjustRelaxExpr(uint32_t Type,
819                                                 const uint8_t *Data,
820                                                 RelExpr RelExpr) const {
821   if (Type != R_X86_64_GOTPCRELX && Type != R_X86_64_REX_GOTPCRELX)
822     return RelExpr;
823   const uint8_t Op = Data[-2];
824   const uint8_t ModRm = Data[-1];
825   // FIXME: When PIC is disabled and foo is defined locally in the
826   // lower 32 bit address space, memory operand in mov can be converted into
827   // immediate operand. Otherwise, mov must be changed to lea. We support only
828   // latter relaxation at this moment.
829   if (Op == 0x8b)
830     return R_RELAX_GOT_PC;
831   // Relax call and jmp.
832   if (Op == 0xff && (ModRm == 0x15 || ModRm == 0x25))
833     return R_RELAX_GOT_PC;
834 
835   // Relaxation of test, adc, add, and, cmp, or, sbb, sub, xor.
836   // If PIC then no relaxation is available.
837   // We also don't relax test/binop instructions without REX byte,
838   // they are 32bit operations and not common to have.
839   assert(Type == R_X86_64_REX_GOTPCRELX);
840   return Config->Pic ? RelExpr : R_RELAX_GOT_PC_NOPIC;
841 }
842 
843 // A subset of relaxations can only be applied for no-PIC. This method
844 // handles such relaxations. Instructions encoding information was taken from:
845 // "Intel 64 and IA-32 Architectures Software Developer's Manual V2"
846 // (http://www.intel.com/content/dam/www/public/us/en/documents/manuals/
847 //    64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf)
848 template <class ELFT>
849 void X86_64TargetInfo<ELFT>::relaxGotNoPic(uint8_t *Loc, uint64_t Val,
850                                            uint8_t Op, uint8_t ModRm) const {
851   const uint8_t Rex = Loc[-3];
852   // Convert "test %reg, foo@GOTPCREL(%rip)" to "test $foo, %reg".
853   if (Op == 0x85) {
854     // See "TEST-Logical Compare" (4-428 Vol. 2B),
855     // TEST r/m64, r64 uses "full" ModR / M byte (no opcode extension).
856 
857     // ModR/M byte has form XX YYY ZZZ, where
858     // YYY is MODRM.reg(register 2), ZZZ is MODRM.rm(register 1).
859     // XX has different meanings:
860     // 00: The operand's memory address is in reg1.
861     // 01: The operand's memory address is reg1 + a byte-sized displacement.
862     // 10: The operand's memory address is reg1 + a word-sized displacement.
863     // 11: The operand is reg1 itself.
864     // If an instruction requires only one operand, the unused reg2 field
865     // holds extra opcode bits rather than a register code
866     // 0xC0 == 11 000 000 binary.
867     // 0x38 == 00 111 000 binary.
868     // We transfer reg2 to reg1 here as operand.
869     // See "2.1.3 ModR/M and SIB Bytes" (Vol. 2A 2-3).
870     Loc[-1] = 0xc0 | (ModRm & 0x38) >> 3; // ModR/M byte.
871 
872     // Change opcode from TEST r/m64, r64 to TEST r/m64, imm32
873     // See "TEST-Logical Compare" (4-428 Vol. 2B).
874     Loc[-2] = 0xf7;
875 
876     // Move R bit to the B bit in REX byte.
877     // REX byte is encoded as 0100WRXB, where
878     // 0100 is 4bit fixed pattern.
879     // REX.W When 1, a 64-bit operand size is used. Otherwise, when 0, the
880     //   default operand size is used (which is 32-bit for most but not all
881     //   instructions).
882     // REX.R This 1-bit value is an extension to the MODRM.reg field.
883     // REX.X This 1-bit value is an extension to the SIB.index field.
884     // REX.B This 1-bit value is an extension to the MODRM.rm field or the
885     // SIB.base field.
886     // See "2.2.1.2 More on REX Prefix Fields " (2-8 Vol. 2A).
887     Loc[-3] = (Rex & ~0x4) | (Rex & 0x4) >> 2;
888     relocateOne(Loc, R_X86_64_PC32, Val);
889     return;
890   }
891 
892   // If we are here then we need to relax the adc, add, and, cmp, or, sbb, sub
893   // or xor operations.
894 
895   // Convert "binop foo@GOTPCREL(%rip), %reg" to "binop $foo, %reg".
896   // Logic is close to one for test instruction above, but we also
897   // write opcode extension here, see below for details.
898   Loc[-1] = 0xc0 | (ModRm & 0x38) >> 3 | (Op & 0x3c); // ModR/M byte.
899 
900   // Primary opcode is 0x81, opcode extension is one of:
901   // 000b = ADD, 001b is OR, 010b is ADC, 011b is SBB,
902   // 100b is AND, 101b is SUB, 110b is XOR, 111b is CMP.
903   // This value was wrote to MODRM.reg in a line above.
904   // See "3.2 INSTRUCTIONS (A-M)" (Vol. 2A 3-15),
905   // "INSTRUCTION SET REFERENCE, N-Z" (Vol. 2B 4-1) for
906   // descriptions about each operation.
907   Loc[-2] = 0x81;
908   Loc[-3] = (Rex & ~0x4) | (Rex & 0x4) >> 2;
909   relocateOne(Loc, R_X86_64_PC32, Val);
910 }
911 
912 template <class ELFT>
913 void X86_64TargetInfo<ELFT>::relaxGot(uint8_t *Loc, uint64_t Val) const {
914   const uint8_t Op = Loc[-2];
915   const uint8_t ModRm = Loc[-1];
916 
917   // Convert "mov foo@GOTPCREL(%rip),%reg" to "lea foo(%rip),%reg".
918   if (Op == 0x8b) {
919     Loc[-2] = 0x8d;
920     relocateOne(Loc, R_X86_64_PC32, Val);
921     return;
922   }
923 
924   if (Op != 0xff) {
925     // We are relaxing a rip relative to an absolute, so compensate
926     // for the old -4 addend.
927     assert(!Config->Pic);
928     relaxGotNoPic(Loc, Val + 4, Op, ModRm);
929     return;
930   }
931 
932   // Convert call/jmp instructions.
933   if (ModRm == 0x15) {
934     // ABI says we can convert "call *foo@GOTPCREL(%rip)" to "nop; call foo".
935     // Instead we convert to "addr32 call foo" where addr32 is an instruction
936     // prefix. That makes result expression to be a single instruction.
937     Loc[-2] = 0x67; // addr32 prefix
938     Loc[-1] = 0xe8; // call
939     relocateOne(Loc, R_X86_64_PC32, Val);
940     return;
941   }
942 
943   // Convert "jmp *foo@GOTPCREL(%rip)" to "jmp foo; nop".
944   // jmp doesn't return, so it is fine to use nop here, it is just a stub.
945   assert(ModRm == 0x25);
946   Loc[-2] = 0xe9; // jmp
947   Loc[3] = 0x90;  // nop
948   relocateOne(Loc - 1, R_X86_64_PC32, Val + 1);
949 }
950 
951 // Relocation masks following the #lo(value), #hi(value), #ha(value),
952 // #higher(value), #highera(value), #highest(value), and #highesta(value)
953 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
954 // document.
955 static uint16_t applyPPCLo(uint64_t V) { return V; }
956 static uint16_t applyPPCHi(uint64_t V) { return V >> 16; }
957 static uint16_t applyPPCHa(uint64_t V) { return (V + 0x8000) >> 16; }
958 static uint16_t applyPPCHigher(uint64_t V) { return V >> 32; }
959 static uint16_t applyPPCHighera(uint64_t V) { return (V + 0x8000) >> 32; }
960 static uint16_t applyPPCHighest(uint64_t V) { return V >> 48; }
961 static uint16_t applyPPCHighesta(uint64_t V) { return (V + 0x8000) >> 48; }
962 
963 PPCTargetInfo::PPCTargetInfo() {}
964 
965 void PPCTargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
966                                 uint64_t Val) const {
967   switch (Type) {
968   case R_PPC_ADDR16_HA:
969     write16be(Loc, applyPPCHa(Val));
970     break;
971   case R_PPC_ADDR16_LO:
972     write16be(Loc, applyPPCLo(Val));
973     break;
974   case R_PPC_ADDR32:
975   case R_PPC_REL32:
976     write32be(Loc, Val);
977     break;
978   case R_PPC_REL24:
979     or32be(Loc, Val & 0x3FFFFFC);
980     break;
981   default:
982     fatal("unrecognized reloc " + Twine(Type));
983   }
984 }
985 
986 RelExpr PPCTargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
987   switch (Type) {
988   case R_PPC_REL24:
989   case R_PPC_REL32:
990     return R_PC;
991   default:
992     return R_ABS;
993   }
994 }
995 
996 PPC64TargetInfo::PPC64TargetInfo() {
997   PltRel = GotRel = R_PPC64_GLOB_DAT;
998   RelativeRel = R_PPC64_RELATIVE;
999   GotEntrySize = 8;
1000   GotPltEntrySize = 8;
1001   PltEntrySize = 32;
1002   PltHeaderSize = 0;
1003 
1004   // We need 64K pages (at least under glibc/Linux, the loader won't
1005   // set different permissions on a finer granularity than that).
1006   MaxPageSize = 65536;
1007 
1008   // The PPC64 ELF ABI v1 spec, says:
1009   //
1010   //   It is normally desirable to put segments with different characteristics
1011   //   in separate 256 Mbyte portions of the address space, to give the
1012   //   operating system full paging flexibility in the 64-bit address space.
1013   //
1014   // And because the lowest non-zero 256M boundary is 0x10000000, PPC64 linkers
1015   // use 0x10000000 as the starting address.
1016   DefaultImageBase = 0x10000000;
1017 }
1018 
1019 static uint64_t PPC64TocOffset = 0x8000;
1020 
1021 uint64_t getPPC64TocBase() {
1022   // The TOC consists of sections .got, .toc, .tocbss, .plt in that order. The
1023   // TOC starts where the first of these sections starts. We always create a
1024   // .got when we see a relocation that uses it, so for us the start is always
1025   // the .got.
1026   uint64_t TocVA = In<ELF64BE>::Got->getVA();
1027 
1028   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
1029   // thus permitting a full 64 Kbytes segment. Note that the glibc startup
1030   // code (crt1.o) assumes that you can get from the TOC base to the
1031   // start of the .toc section with only a single (signed) 16-bit relocation.
1032   return TocVA + PPC64TocOffset;
1033 }
1034 
1035 RelExpr PPC64TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
1036   switch (Type) {
1037   default:
1038     return R_ABS;
1039   case R_PPC64_TOC16:
1040   case R_PPC64_TOC16_DS:
1041   case R_PPC64_TOC16_HA:
1042   case R_PPC64_TOC16_HI:
1043   case R_PPC64_TOC16_LO:
1044   case R_PPC64_TOC16_LO_DS:
1045     return R_GOTREL;
1046   case R_PPC64_TOC:
1047     return R_PPC_TOC;
1048   case R_PPC64_REL24:
1049     return R_PPC_PLT_OPD;
1050   }
1051 }
1052 
1053 void PPC64TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
1054                                uint64_t PltEntryAddr, int32_t Index,
1055                                unsigned RelOff) const {
1056   uint64_t Off = GotEntryAddr - getPPC64TocBase();
1057 
1058   // FIXME: What we should do, in theory, is get the offset of the function
1059   // descriptor in the .opd section, and use that as the offset from %r2 (the
1060   // TOC-base pointer). Instead, we have the GOT-entry offset, and that will
1061   // be a pointer to the function descriptor in the .opd section. Using
1062   // this scheme is simpler, but requires an extra indirection per PLT dispatch.
1063 
1064   write32be(Buf, 0xf8410028);                       // std %r2, 40(%r1)
1065   write32be(Buf + 4, 0x3d620000 | applyPPCHa(Off)); // addis %r11, %r2, X@ha
1066   write32be(Buf + 8, 0xe98b0000 | applyPPCLo(Off)); // ld %r12, X@l(%r11)
1067   write32be(Buf + 12, 0xe96c0000);                  // ld %r11,0(%r12)
1068   write32be(Buf + 16, 0x7d6903a6);                  // mtctr %r11
1069   write32be(Buf + 20, 0xe84c0008);                  // ld %r2,8(%r12)
1070   write32be(Buf + 24, 0xe96c0010);                  // ld %r11,16(%r12)
1071   write32be(Buf + 28, 0x4e800420);                  // bctr
1072 }
1073 
1074 static std::pair<uint32_t, uint64_t> toAddr16Rel(uint32_t Type, uint64_t Val) {
1075   uint64_t V = Val - PPC64TocOffset;
1076   switch (Type) {
1077   case R_PPC64_TOC16:
1078     return {R_PPC64_ADDR16, V};
1079   case R_PPC64_TOC16_DS:
1080     return {R_PPC64_ADDR16_DS, V};
1081   case R_PPC64_TOC16_HA:
1082     return {R_PPC64_ADDR16_HA, V};
1083   case R_PPC64_TOC16_HI:
1084     return {R_PPC64_ADDR16_HI, V};
1085   case R_PPC64_TOC16_LO:
1086     return {R_PPC64_ADDR16_LO, V};
1087   case R_PPC64_TOC16_LO_DS:
1088     return {R_PPC64_ADDR16_LO_DS, V};
1089   default:
1090     return {Type, Val};
1091   }
1092 }
1093 
1094 void PPC64TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
1095                                   uint64_t Val) const {
1096   // For a TOC-relative relocation, proceed in terms of the corresponding
1097   // ADDR16 relocation type.
1098   std::tie(Type, Val) = toAddr16Rel(Type, Val);
1099 
1100   switch (Type) {
1101   case R_PPC64_ADDR14: {
1102     checkAlignment<4>(Val, Type);
1103     // Preserve the AA/LK bits in the branch instruction
1104     uint8_t AALK = Loc[3];
1105     write16be(Loc + 2, (AALK & 3) | (Val & 0xfffc));
1106     break;
1107   }
1108   case R_PPC64_ADDR16:
1109     checkInt<16>(Val, Type);
1110     write16be(Loc, Val);
1111     break;
1112   case R_PPC64_ADDR16_DS:
1113     checkInt<16>(Val, Type);
1114     write16be(Loc, (read16be(Loc) & 3) | (Val & ~3));
1115     break;
1116   case R_PPC64_ADDR16_HA:
1117   case R_PPC64_REL16_HA:
1118     write16be(Loc, applyPPCHa(Val));
1119     break;
1120   case R_PPC64_ADDR16_HI:
1121   case R_PPC64_REL16_HI:
1122     write16be(Loc, applyPPCHi(Val));
1123     break;
1124   case R_PPC64_ADDR16_HIGHER:
1125     write16be(Loc, applyPPCHigher(Val));
1126     break;
1127   case R_PPC64_ADDR16_HIGHERA:
1128     write16be(Loc, applyPPCHighera(Val));
1129     break;
1130   case R_PPC64_ADDR16_HIGHEST:
1131     write16be(Loc, applyPPCHighest(Val));
1132     break;
1133   case R_PPC64_ADDR16_HIGHESTA:
1134     write16be(Loc, applyPPCHighesta(Val));
1135     break;
1136   case R_PPC64_ADDR16_LO:
1137     write16be(Loc, applyPPCLo(Val));
1138     break;
1139   case R_PPC64_ADDR16_LO_DS:
1140   case R_PPC64_REL16_LO:
1141     write16be(Loc, (read16be(Loc) & 3) | (applyPPCLo(Val) & ~3));
1142     break;
1143   case R_PPC64_ADDR32:
1144   case R_PPC64_REL32:
1145     checkInt<32>(Val, Type);
1146     write32be(Loc, Val);
1147     break;
1148   case R_PPC64_ADDR64:
1149   case R_PPC64_REL64:
1150   case R_PPC64_TOC:
1151     write64be(Loc, Val);
1152     break;
1153   case R_PPC64_REL24: {
1154     uint32_t Mask = 0x03FFFFFC;
1155     checkInt<24>(Val, Type);
1156     write32be(Loc, (read32be(Loc) & ~Mask) | (Val & Mask));
1157     break;
1158   }
1159   default:
1160     fatal("unrecognized reloc " + Twine(Type));
1161   }
1162 }
1163 
1164 AArch64TargetInfo::AArch64TargetInfo() {
1165   CopyRel = R_AARCH64_COPY;
1166   RelativeRel = R_AARCH64_RELATIVE;
1167   IRelativeRel = R_AARCH64_IRELATIVE;
1168   GotRel = R_AARCH64_GLOB_DAT;
1169   PltRel = R_AARCH64_JUMP_SLOT;
1170   TlsDescRel = R_AARCH64_TLSDESC;
1171   TlsGotRel = R_AARCH64_TLS_TPREL64;
1172   GotEntrySize = 8;
1173   GotPltEntrySize = 8;
1174   PltEntrySize = 16;
1175   PltHeaderSize = 32;
1176   MaxPageSize = 65536;
1177 
1178   // It doesn't seem to be documented anywhere, but tls on aarch64 uses variant
1179   // 1 of the tls structures and the tcb size is 16.
1180   TcbSize = 16;
1181 }
1182 
1183 RelExpr AArch64TargetInfo::getRelExpr(uint32_t Type,
1184                                       const SymbolBody &S) const {
1185   switch (Type) {
1186   default:
1187     return R_ABS;
1188   case R_AARCH64_TLSDESC_ADR_PAGE21:
1189     return R_TLSDESC_PAGE;
1190   case R_AARCH64_TLSDESC_LD64_LO12_NC:
1191   case R_AARCH64_TLSDESC_ADD_LO12_NC:
1192     return R_TLSDESC;
1193   case R_AARCH64_TLSDESC_CALL:
1194     return R_TLSDESC_CALL;
1195   case R_AARCH64_TLSLE_ADD_TPREL_HI12:
1196   case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
1197     return R_TLS;
1198   case R_AARCH64_CALL26:
1199   case R_AARCH64_CONDBR19:
1200   case R_AARCH64_JUMP26:
1201   case R_AARCH64_TSTBR14:
1202     return R_PLT_PC;
1203   case R_AARCH64_PREL16:
1204   case R_AARCH64_PREL32:
1205   case R_AARCH64_PREL64:
1206   case R_AARCH64_ADR_PREL_LO21:
1207     return R_PC;
1208   case R_AARCH64_ADR_PREL_PG_HI21:
1209     return R_PAGE_PC;
1210   case R_AARCH64_LD64_GOT_LO12_NC:
1211   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
1212     return R_GOT;
1213   case R_AARCH64_ADR_GOT_PAGE:
1214   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
1215     return R_GOT_PAGE_PC;
1216   }
1217 }
1218 
1219 RelExpr AArch64TargetInfo::adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
1220                                            RelExpr Expr) const {
1221   if (Expr == R_RELAX_TLS_GD_TO_IE) {
1222     if (Type == R_AARCH64_TLSDESC_ADR_PAGE21)
1223       return R_RELAX_TLS_GD_TO_IE_PAGE_PC;
1224     return R_RELAX_TLS_GD_TO_IE_ABS;
1225   }
1226   return Expr;
1227 }
1228 
1229 bool AArch64TargetInfo::usesOnlyLowPageBits(uint32_t Type) const {
1230   switch (Type) {
1231   default:
1232     return false;
1233   case R_AARCH64_ADD_ABS_LO12_NC:
1234   case R_AARCH64_LD64_GOT_LO12_NC:
1235   case R_AARCH64_LDST128_ABS_LO12_NC:
1236   case R_AARCH64_LDST16_ABS_LO12_NC:
1237   case R_AARCH64_LDST32_ABS_LO12_NC:
1238   case R_AARCH64_LDST64_ABS_LO12_NC:
1239   case R_AARCH64_LDST8_ABS_LO12_NC:
1240   case R_AARCH64_TLSDESC_ADD_LO12_NC:
1241   case R_AARCH64_TLSDESC_LD64_LO12_NC:
1242   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
1243     return true;
1244   }
1245 }
1246 
1247 bool AArch64TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
1248   return Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 ||
1249          Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC;
1250 }
1251 
1252 uint32_t AArch64TargetInfo::getDynRel(uint32_t Type) const {
1253   if (Type == R_AARCH64_ABS32 || Type == R_AARCH64_ABS64)
1254     return Type;
1255   // Keep it going with a dummy value so that we can find more reloc errors.
1256   errorDynRel(Type);
1257   return R_AARCH64_ABS32;
1258 }
1259 
1260 void AArch64TargetInfo::writeGotPlt(uint8_t *Buf, const SymbolBody &) const {
1261   write64le(Buf, In<ELF64LE>::Plt->getVA());
1262 }
1263 
1264 static uint64_t getAArch64Page(uint64_t Expr) {
1265   return Expr & (~static_cast<uint64_t>(0xFFF));
1266 }
1267 
1268 void AArch64TargetInfo::writePltHeader(uint8_t *Buf) const {
1269   const uint8_t PltData[] = {
1270       0xf0, 0x7b, 0xbf, 0xa9, // stp	x16, x30, [sp,#-16]!
1271       0x10, 0x00, 0x00, 0x90, // adrp	x16, Page(&(.plt.got[2]))
1272       0x11, 0x02, 0x40, 0xf9, // ldr	x17, [x16, Offset(&(.plt.got[2]))]
1273       0x10, 0x02, 0x00, 0x91, // add	x16, x16, Offset(&(.plt.got[2]))
1274       0x20, 0x02, 0x1f, 0xd6, // br	x17
1275       0x1f, 0x20, 0x03, 0xd5, // nop
1276       0x1f, 0x20, 0x03, 0xd5, // nop
1277       0x1f, 0x20, 0x03, 0xd5  // nop
1278   };
1279   memcpy(Buf, PltData, sizeof(PltData));
1280 
1281   uint64_t Got = In<ELF64LE>::GotPlt->getVA();
1282   uint64_t Plt = In<ELF64LE>::Plt->getVA();
1283   relocateOne(Buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
1284               getAArch64Page(Got + 16) - getAArch64Page(Plt + 4));
1285   relocateOne(Buf + 8, R_AARCH64_LDST64_ABS_LO12_NC, Got + 16);
1286   relocateOne(Buf + 12, R_AARCH64_ADD_ABS_LO12_NC, Got + 16);
1287 }
1288 
1289 void AArch64TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
1290                                  uint64_t PltEntryAddr, int32_t Index,
1291                                  unsigned RelOff) const {
1292   const uint8_t Inst[] = {
1293       0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[n]))
1294       0x11, 0x02, 0x40, 0xf9, // ldr  x17, [x16, Offset(&(.plt.got[n]))]
1295       0x10, 0x02, 0x00, 0x91, // add  x16, x16, Offset(&(.plt.got[n]))
1296       0x20, 0x02, 0x1f, 0xd6  // br   x17
1297   };
1298   memcpy(Buf, Inst, sizeof(Inst));
1299 
1300   relocateOne(Buf, R_AARCH64_ADR_PREL_PG_HI21,
1301               getAArch64Page(GotEntryAddr) - getAArch64Page(PltEntryAddr));
1302   relocateOne(Buf + 4, R_AARCH64_LDST64_ABS_LO12_NC, GotEntryAddr);
1303   relocateOne(Buf + 8, R_AARCH64_ADD_ABS_LO12_NC, GotEntryAddr);
1304 }
1305 
1306 static void updateAArch64Addr(uint8_t *L, uint64_t Imm) {
1307   uint32_t ImmLo = (Imm & 0x3) << 29;
1308   uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
1309   uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
1310   write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
1311 }
1312 
1313 static inline void updateAArch64Add(uint8_t *L, uint64_t Imm) {
1314   or32le(L, (Imm & 0xFFF) << 10);
1315 }
1316 
1317 void AArch64TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
1318                                     uint64_t Val) const {
1319   switch (Type) {
1320   case R_AARCH64_ABS16:
1321   case R_AARCH64_PREL16:
1322     checkIntUInt<16>(Val, Type);
1323     write16le(Loc, Val);
1324     break;
1325   case R_AARCH64_ABS32:
1326   case R_AARCH64_PREL32:
1327     checkIntUInt<32>(Val, Type);
1328     write32le(Loc, Val);
1329     break;
1330   case R_AARCH64_ABS64:
1331   case R_AARCH64_PREL64:
1332     write64le(Loc, Val);
1333     break;
1334   case R_AARCH64_ADD_ABS_LO12_NC:
1335     // This relocation stores 12 bits and there's no instruction
1336     // to do it. Instead, we do a 32 bits store of the value
1337     // of r_addend bitwise-or'ed Loc. This assumes that the addend
1338     // bits in Loc are zero.
1339     or32le(Loc, (Val & 0xFFF) << 10);
1340     break;
1341   case R_AARCH64_ADR_GOT_PAGE:
1342   case R_AARCH64_ADR_PREL_PG_HI21:
1343   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
1344   case R_AARCH64_TLSDESC_ADR_PAGE21:
1345     checkInt<33>(Val, Type);
1346     updateAArch64Addr(Loc, Val >> 12);
1347     break;
1348   case R_AARCH64_ADR_PREL_LO21:
1349     checkInt<21>(Val, Type);
1350     updateAArch64Addr(Loc, Val);
1351     break;
1352   case R_AARCH64_CALL26:
1353   case R_AARCH64_JUMP26:
1354     checkInt<28>(Val, Type);
1355     or32le(Loc, (Val & 0x0FFFFFFC) >> 2);
1356     break;
1357   case R_AARCH64_CONDBR19:
1358     checkInt<21>(Val, Type);
1359     or32le(Loc, (Val & 0x1FFFFC) << 3);
1360     break;
1361   case R_AARCH64_LD64_GOT_LO12_NC:
1362   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
1363   case R_AARCH64_TLSDESC_LD64_LO12_NC:
1364     checkAlignment<8>(Val, Type);
1365     or32le(Loc, (Val & 0xFF8) << 7);
1366     break;
1367   case R_AARCH64_LDST128_ABS_LO12_NC:
1368     or32le(Loc, (Val & 0x0FF8) << 6);
1369     break;
1370   case R_AARCH64_LDST16_ABS_LO12_NC:
1371     or32le(Loc, (Val & 0x0FFC) << 9);
1372     break;
1373   case R_AARCH64_LDST8_ABS_LO12_NC:
1374     or32le(Loc, (Val & 0xFFF) << 10);
1375     break;
1376   case R_AARCH64_LDST32_ABS_LO12_NC:
1377     or32le(Loc, (Val & 0xFFC) << 8);
1378     break;
1379   case R_AARCH64_LDST64_ABS_LO12_NC:
1380     or32le(Loc, (Val & 0xFF8) << 7);
1381     break;
1382   case R_AARCH64_MOVW_UABS_G0_NC:
1383     or32le(Loc, (Val & 0xFFFF) << 5);
1384     break;
1385   case R_AARCH64_MOVW_UABS_G1_NC:
1386     or32le(Loc, (Val & 0xFFFF0000) >> 11);
1387     break;
1388   case R_AARCH64_MOVW_UABS_G2_NC:
1389     or32le(Loc, (Val & 0xFFFF00000000) >> 27);
1390     break;
1391   case R_AARCH64_MOVW_UABS_G3:
1392     or32le(Loc, (Val & 0xFFFF000000000000) >> 43);
1393     break;
1394   case R_AARCH64_TSTBR14:
1395     checkInt<16>(Val, Type);
1396     or32le(Loc, (Val & 0xFFFC) << 3);
1397     break;
1398   case R_AARCH64_TLSLE_ADD_TPREL_HI12:
1399     checkInt<24>(Val, Type);
1400     updateAArch64Add(Loc, Val >> 12);
1401     break;
1402   case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
1403   case R_AARCH64_TLSDESC_ADD_LO12_NC:
1404     updateAArch64Add(Loc, Val);
1405     break;
1406   default:
1407     fatal("unrecognized reloc " + Twine(Type));
1408   }
1409 }
1410 
1411 void AArch64TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
1412                                        uint64_t Val) const {
1413   // TLSDESC Global-Dynamic relocation are in the form:
1414   //   adrp    x0, :tlsdesc:v             [R_AARCH64_TLSDESC_ADR_PAGE21]
1415   //   ldr     x1, [x0, #:tlsdesc_lo12:v  [R_AARCH64_TLSDESC_LD64_LO12_NC]
1416   //   add     x0, x0, :tlsdesc_los:v     [_AARCH64_TLSDESC_ADD_LO12_NC]
1417   //   .tlsdesccall                       [R_AARCH64_TLSDESC_CALL]
1418   //   blr     x1
1419   // And it can optimized to:
1420   //   movz    x0, #0x0, lsl #16
1421   //   movk    x0, #0x10
1422   //   nop
1423   //   nop
1424   checkUInt<32>(Val, Type);
1425 
1426   switch (Type) {
1427   case R_AARCH64_TLSDESC_ADD_LO12_NC:
1428   case R_AARCH64_TLSDESC_CALL:
1429     write32le(Loc, 0xd503201f); // nop
1430     return;
1431   case R_AARCH64_TLSDESC_ADR_PAGE21:
1432     write32le(Loc, 0xd2a00000 | (((Val >> 16) & 0xffff) << 5)); // movz
1433     return;
1434   case R_AARCH64_TLSDESC_LD64_LO12_NC:
1435     write32le(Loc, 0xf2800000 | ((Val & 0xffff) << 5)); // movk
1436     return;
1437   default:
1438     llvm_unreachable("unsupported relocation for TLS GD to LE relaxation");
1439   }
1440 }
1441 
1442 void AArch64TargetInfo::relaxTlsGdToIe(uint8_t *Loc, uint32_t Type,
1443                                        uint64_t Val) const {
1444   // TLSDESC Global-Dynamic relocation are in the form:
1445   //   adrp    x0, :tlsdesc:v             [R_AARCH64_TLSDESC_ADR_PAGE21]
1446   //   ldr     x1, [x0, #:tlsdesc_lo12:v  [R_AARCH64_TLSDESC_LD64_LO12_NC]
1447   //   add     x0, x0, :tlsdesc_los:v     [_AARCH64_TLSDESC_ADD_LO12_NC]
1448   //   .tlsdesccall                       [R_AARCH64_TLSDESC_CALL]
1449   //   blr     x1
1450   // And it can optimized to:
1451   //   adrp    x0, :gottprel:v
1452   //   ldr     x0, [x0, :gottprel_lo12:v]
1453   //   nop
1454   //   nop
1455 
1456   switch (Type) {
1457   case R_AARCH64_TLSDESC_ADD_LO12_NC:
1458   case R_AARCH64_TLSDESC_CALL:
1459     write32le(Loc, 0xd503201f); // nop
1460     break;
1461   case R_AARCH64_TLSDESC_ADR_PAGE21:
1462     write32le(Loc, 0x90000000); // adrp
1463     relocateOne(Loc, R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21, Val);
1464     break;
1465   case R_AARCH64_TLSDESC_LD64_LO12_NC:
1466     write32le(Loc, 0xf9400000); // ldr
1467     relocateOne(Loc, R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC, Val);
1468     break;
1469   default:
1470     llvm_unreachable("unsupported relocation for TLS GD to LE relaxation");
1471   }
1472 }
1473 
1474 void AArch64TargetInfo::relaxTlsIeToLe(uint8_t *Loc, uint32_t Type,
1475                                        uint64_t Val) const {
1476   checkUInt<32>(Val, Type);
1477 
1478   if (Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) {
1479     // Generate MOVZ.
1480     uint32_t RegNo = read32le(Loc) & 0x1f;
1481     write32le(Loc, (0xd2a00000 | RegNo) | (((Val >> 16) & 0xffff) << 5));
1482     return;
1483   }
1484   if (Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) {
1485     // Generate MOVK.
1486     uint32_t RegNo = read32le(Loc) & 0x1f;
1487     write32le(Loc, (0xf2800000 | RegNo) | ((Val & 0xffff) << 5));
1488     return;
1489   }
1490   llvm_unreachable("invalid relocation for TLS IE to LE relaxation");
1491 }
1492 
1493 AMDGPUTargetInfo::AMDGPUTargetInfo() {
1494   RelativeRel = R_AMDGPU_REL64;
1495   GotRel = R_AMDGPU_ABS64;
1496   GotEntrySize = 8;
1497 }
1498 
1499 void AMDGPUTargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
1500                                    uint64_t Val) const {
1501   switch (Type) {
1502   case R_AMDGPU_ABS32:
1503   case R_AMDGPU_GOTPCREL:
1504   case R_AMDGPU_GOTPCREL32_LO:
1505   case R_AMDGPU_REL32:
1506   case R_AMDGPU_REL32_LO:
1507     write32le(Loc, Val);
1508     break;
1509   case R_AMDGPU_ABS64:
1510     write64le(Loc, Val);
1511     break;
1512   case R_AMDGPU_GOTPCREL32_HI:
1513   case R_AMDGPU_REL32_HI:
1514     write32le(Loc, Val >> 32);
1515     break;
1516   default:
1517     fatal("unrecognized reloc " + Twine(Type));
1518   }
1519 }
1520 
1521 RelExpr AMDGPUTargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
1522   switch (Type) {
1523   case R_AMDGPU_ABS32:
1524   case R_AMDGPU_ABS64:
1525     return R_ABS;
1526   case R_AMDGPU_REL32:
1527   case R_AMDGPU_REL32_LO:
1528   case R_AMDGPU_REL32_HI:
1529     return R_PC;
1530   case R_AMDGPU_GOTPCREL:
1531   case R_AMDGPU_GOTPCREL32_LO:
1532   case R_AMDGPU_GOTPCREL32_HI:
1533     return R_GOT_PC;
1534   default:
1535     fatal("do not know how to handle relocation " + Twine(Type));
1536   }
1537 }
1538 
1539 ARMTargetInfo::ARMTargetInfo() {
1540   CopyRel = R_ARM_COPY;
1541   RelativeRel = R_ARM_RELATIVE;
1542   IRelativeRel = R_ARM_IRELATIVE;
1543   GotRel = R_ARM_GLOB_DAT;
1544   PltRel = R_ARM_JUMP_SLOT;
1545   TlsGotRel = R_ARM_TLS_TPOFF32;
1546   TlsModuleIndexRel = R_ARM_TLS_DTPMOD32;
1547   TlsOffsetRel = R_ARM_TLS_DTPOFF32;
1548   GotEntrySize = 4;
1549   GotPltEntrySize = 4;
1550   PltEntrySize = 16;
1551   PltHeaderSize = 20;
1552   // ARM uses Variant 1 TLS
1553   TcbSize = 8;
1554   NeedsThunks = true;
1555 }
1556 
1557 RelExpr ARMTargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
1558   switch (Type) {
1559   default:
1560     return R_ABS;
1561   case R_ARM_THM_JUMP11:
1562     return R_PC;
1563   case R_ARM_CALL:
1564   case R_ARM_JUMP24:
1565   case R_ARM_PC24:
1566   case R_ARM_PLT32:
1567   case R_ARM_PREL31:
1568   case R_ARM_THM_JUMP19:
1569   case R_ARM_THM_JUMP24:
1570   case R_ARM_THM_CALL:
1571     return R_PLT_PC;
1572   case R_ARM_GOTOFF32:
1573     // (S + A) - GOT_ORG
1574     return R_GOTREL;
1575   case R_ARM_GOT_BREL:
1576     // GOT(S) + A - GOT_ORG
1577     return R_GOT_OFF;
1578   case R_ARM_GOT_PREL:
1579   case R_ARM_TLS_IE32:
1580     // GOT(S) + A - P
1581     return R_GOT_PC;
1582   case R_ARM_TARGET1:
1583     return Config->Target1Rel ? R_PC : R_ABS;
1584   case R_ARM_TARGET2:
1585     if (Config->Target2 == Target2Policy::Rel)
1586       return R_PC;
1587     if (Config->Target2 == Target2Policy::Abs)
1588       return R_ABS;
1589     return R_GOT_PC;
1590   case R_ARM_TLS_GD32:
1591     return R_TLSGD_PC;
1592   case R_ARM_TLS_LDM32:
1593     return R_TLSLD_PC;
1594   case R_ARM_BASE_PREL:
1595     // B(S) + A - P
1596     // FIXME: currently B(S) assumed to be .got, this may not hold for all
1597     // platforms.
1598     return R_GOTONLY_PC;
1599   case R_ARM_MOVW_PREL_NC:
1600   case R_ARM_MOVT_PREL:
1601   case R_ARM_REL32:
1602   case R_ARM_THM_MOVW_PREL_NC:
1603   case R_ARM_THM_MOVT_PREL:
1604     return R_PC;
1605   case R_ARM_NONE:
1606     return R_HINT;
1607   case R_ARM_TLS_LE32:
1608     return R_TLS;
1609   }
1610 }
1611 
1612 uint32_t ARMTargetInfo::getDynRel(uint32_t Type) const {
1613   if (Type == R_ARM_TARGET1 && !Config->Target1Rel)
1614     return R_ARM_ABS32;
1615   if (Type == R_ARM_ABS32)
1616     return Type;
1617   // Keep it going with a dummy value so that we can find more reloc errors.
1618   errorDynRel(Type);
1619   return R_ARM_ABS32;
1620 }
1621 
1622 void ARMTargetInfo::writeGotPlt(uint8_t *Buf, const SymbolBody &) const {
1623   write32le(Buf, In<ELF32LE>::Plt->getVA());
1624 }
1625 
1626 void ARMTargetInfo::writePltHeader(uint8_t *Buf) const {
1627   const uint8_t PltData[] = {
1628       0x04, 0xe0, 0x2d, 0xe5, //     str lr, [sp,#-4]!
1629       0x04, 0xe0, 0x9f, 0xe5, //     ldr lr, L2
1630       0x0e, 0xe0, 0x8f, 0xe0, // L1: add lr, pc, lr
1631       0x08, 0xf0, 0xbe, 0xe5, //     ldr pc, [lr, #8]
1632       0x00, 0x00, 0x00, 0x00, // L2: .word   &(.got.plt) - L1 - 8
1633   };
1634   memcpy(Buf, PltData, sizeof(PltData));
1635   uint64_t GotPlt = In<ELF32LE>::GotPlt->getVA();
1636   uint64_t L1 = In<ELF32LE>::Plt->getVA() + 8;
1637   write32le(Buf + 16, GotPlt - L1 - 8);
1638 }
1639 
1640 void ARMTargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
1641                              uint64_t PltEntryAddr, int32_t Index,
1642                              unsigned RelOff) const {
1643   // FIXME: Using simple code sequence with simple relocations.
1644   // There is a more optimal sequence but it requires support for the group
1645   // relocations. See ELF for the ARM Architecture Appendix A.3
1646   const uint8_t PltData[] = {
1647       0x04, 0xc0, 0x9f, 0xe5, //     ldr ip, L2
1648       0x0f, 0xc0, 0x8c, 0xe0, // L1: add ip, ip, pc
1649       0x00, 0xf0, 0x9c, 0xe5, //     ldr pc, [ip]
1650       0x00, 0x00, 0x00, 0x00, // L2: .word   Offset(&(.plt.got) - L1 - 8
1651   };
1652   memcpy(Buf, PltData, sizeof(PltData));
1653   uint64_t L1 = PltEntryAddr + 4;
1654   write32le(Buf + 12, GotEntryAddr - L1 - 8);
1655 }
1656 
1657 RelExpr ARMTargetInfo::getThunkExpr(RelExpr Expr, uint32_t RelocType,
1658                                     const InputFile &File,
1659                                     const SymbolBody &S) const {
1660   // If S is an undefined weak symbol we don't need a Thunk
1661   if (S.isUndefined())
1662     return Expr;
1663   // A state change from ARM to Thumb and vice versa must go through an
1664   // interworking thunk if the relocation type is not R_ARM_CALL or
1665   // R_ARM_THM_CALL.
1666   switch (RelocType) {
1667   case R_ARM_PC24:
1668   case R_ARM_PLT32:
1669   case R_ARM_JUMP24:
1670     // Source is ARM, all PLT entries are ARM so no interworking required.
1671     // Otherwise we need to interwork if Symbol has bit 0 set (Thumb).
1672     if (Expr == R_PC && ((S.getVA<ELF32LE>() & 1) == 1))
1673       return R_THUNK_PC;
1674     break;
1675   case R_ARM_THM_JUMP19:
1676   case R_ARM_THM_JUMP24:
1677     // Source is Thumb, all PLT entries are ARM so interworking is required.
1678     // Otherwise we need to interwork if Symbol has bit 0 clear (ARM).
1679     if (Expr == R_PLT_PC)
1680       return R_THUNK_PLT_PC;
1681     if ((S.getVA<ELF32LE>() & 1) == 0)
1682       return R_THUNK_PC;
1683     break;
1684   }
1685   return Expr;
1686 }
1687 
1688 void ARMTargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
1689                                 uint64_t Val) const {
1690   switch (Type) {
1691   case R_ARM_ABS32:
1692   case R_ARM_BASE_PREL:
1693   case R_ARM_GOTOFF32:
1694   case R_ARM_GOT_BREL:
1695   case R_ARM_GOT_PREL:
1696   case R_ARM_REL32:
1697   case R_ARM_TARGET1:
1698   case R_ARM_TARGET2:
1699   case R_ARM_TLS_GD32:
1700   case R_ARM_TLS_IE32:
1701   case R_ARM_TLS_LDM32:
1702   case R_ARM_TLS_LDO32:
1703   case R_ARM_TLS_LE32:
1704     write32le(Loc, Val);
1705     break;
1706   case R_ARM_PREL31:
1707     checkInt<31>(Val, Type);
1708     write32le(Loc, (read32le(Loc) & 0x80000000) | (Val & ~0x80000000));
1709     break;
1710   case R_ARM_CALL:
1711     // R_ARM_CALL is used for BL and BLX instructions, depending on the
1712     // value of bit 0 of Val, we must select a BL or BLX instruction
1713     if (Val & 1) {
1714       // If bit 0 of Val is 1 the target is Thumb, we must select a BLX.
1715       // The BLX encoding is 0xfa:H:imm24 where Val = imm24:H:'1'
1716       checkInt<26>(Val, Type);
1717       write32le(Loc, 0xfa000000 |                    // opcode
1718                          ((Val & 2) << 23) |         // H
1719                          ((Val >> 2) & 0x00ffffff)); // imm24
1720       break;
1721     }
1722     if ((read32le(Loc) & 0xfe000000) == 0xfa000000)
1723       // BLX (always unconditional) instruction to an ARM Target, select an
1724       // unconditional BL.
1725       write32le(Loc, 0xeb000000 | (read32le(Loc) & 0x00ffffff));
1726   // fall through as BL encoding is shared with B
1727   case R_ARM_JUMP24:
1728   case R_ARM_PC24:
1729   case R_ARM_PLT32:
1730     checkInt<26>(Val, Type);
1731     write32le(Loc, (read32le(Loc) & ~0x00ffffff) | ((Val >> 2) & 0x00ffffff));
1732     break;
1733   case R_ARM_THM_JUMP11:
1734     checkInt<12>(Val, Type);
1735     write16le(Loc, (read32le(Loc) & 0xf800) | ((Val >> 1) & 0x07ff));
1736     break;
1737   case R_ARM_THM_JUMP19:
1738     // Encoding T3: Val = S:J2:J1:imm6:imm11:0
1739     checkInt<21>(Val, Type);
1740     write16le(Loc,
1741               (read16le(Loc) & 0xfbc0) |   // opcode cond
1742                   ((Val >> 10) & 0x0400) | // S
1743                   ((Val >> 12) & 0x003f)); // imm6
1744     write16le(Loc + 2,
1745               0x8000 |                    // opcode
1746                   ((Val >> 8) & 0x0800) | // J2
1747                   ((Val >> 5) & 0x2000) | // J1
1748                   ((Val >> 1) & 0x07ff)); // imm11
1749     break;
1750   case R_ARM_THM_CALL:
1751     // R_ARM_THM_CALL is used for BL and BLX instructions, depending on the
1752     // value of bit 0 of Val, we must select a BL or BLX instruction
1753     if ((Val & 1) == 0) {
1754       // Ensure BLX destination is 4-byte aligned. As BLX instruction may
1755       // only be two byte aligned. This must be done before overflow check
1756       Val = alignTo(Val, 4);
1757     }
1758     // Bit 12 is 0 for BLX, 1 for BL
1759     write16le(Loc + 2, (read16le(Loc + 2) & ~0x1000) | (Val & 1) << 12);
1760   // Fall through as rest of encoding is the same as B.W
1761   case R_ARM_THM_JUMP24:
1762     // Encoding B  T4, BL T1, BLX T2: Val = S:I1:I2:imm10:imm11:0
1763     // FIXME: Use of I1 and I2 require v6T2ops
1764     checkInt<25>(Val, Type);
1765     write16le(Loc,
1766               0xf000 |                     // opcode
1767                   ((Val >> 14) & 0x0400) | // S
1768                   ((Val >> 12) & 0x03ff)); // imm10
1769     write16le(Loc + 2,
1770               (read16le(Loc + 2) & 0xd000) |                  // opcode
1771                   (((~(Val >> 10)) ^ (Val >> 11)) & 0x2000) | // J1
1772                   (((~(Val >> 11)) ^ (Val >> 13)) & 0x0800) | // J2
1773                   ((Val >> 1) & 0x07ff));                     // imm11
1774     break;
1775   case R_ARM_MOVW_ABS_NC:
1776   case R_ARM_MOVW_PREL_NC:
1777     write32le(Loc, (read32le(Loc) & ~0x000f0fff) | ((Val & 0xf000) << 4) |
1778                        (Val & 0x0fff));
1779     break;
1780   case R_ARM_MOVT_ABS:
1781   case R_ARM_MOVT_PREL:
1782     checkInt<32>(Val, Type);
1783     write32le(Loc, (read32le(Loc) & ~0x000f0fff) |
1784                        (((Val >> 16) & 0xf000) << 4) | ((Val >> 16) & 0xfff));
1785     break;
1786   case R_ARM_THM_MOVT_ABS:
1787   case R_ARM_THM_MOVT_PREL:
1788     // Encoding T1: A = imm4:i:imm3:imm8
1789     checkInt<32>(Val, Type);
1790     write16le(Loc,
1791               0xf2c0 |                     // opcode
1792                   ((Val >> 17) & 0x0400) | // i
1793                   ((Val >> 28) & 0x000f)); // imm4
1794     write16le(Loc + 2,
1795               (read16le(Loc + 2) & 0x8f00) | // opcode
1796                   ((Val >> 12) & 0x7000) |   // imm3
1797                   ((Val >> 16) & 0x00ff));   // imm8
1798     break;
1799   case R_ARM_THM_MOVW_ABS_NC:
1800   case R_ARM_THM_MOVW_PREL_NC:
1801     // Encoding T3: A = imm4:i:imm3:imm8
1802     write16le(Loc,
1803               0xf240 |                     // opcode
1804                   ((Val >> 1) & 0x0400) |  // i
1805                   ((Val >> 12) & 0x000f)); // imm4
1806     write16le(Loc + 2,
1807               (read16le(Loc + 2) & 0x8f00) | // opcode
1808                   ((Val << 4) & 0x7000) |    // imm3
1809                   (Val & 0x00ff));           // imm8
1810     break;
1811   default:
1812     fatal("unrecognized reloc " + Twine(Type));
1813   }
1814 }
1815 
1816 uint64_t ARMTargetInfo::getImplicitAddend(const uint8_t *Buf,
1817                                           uint32_t Type) const {
1818   switch (Type) {
1819   default:
1820     return 0;
1821   case R_ARM_ABS32:
1822   case R_ARM_BASE_PREL:
1823   case R_ARM_GOTOFF32:
1824   case R_ARM_GOT_BREL:
1825   case R_ARM_GOT_PREL:
1826   case R_ARM_REL32:
1827   case R_ARM_TARGET1:
1828   case R_ARM_TARGET2:
1829   case R_ARM_TLS_GD32:
1830   case R_ARM_TLS_LDM32:
1831   case R_ARM_TLS_LDO32:
1832   case R_ARM_TLS_IE32:
1833   case R_ARM_TLS_LE32:
1834     return SignExtend64<32>(read32le(Buf));
1835   case R_ARM_PREL31:
1836     return SignExtend64<31>(read32le(Buf));
1837   case R_ARM_CALL:
1838   case R_ARM_JUMP24:
1839   case R_ARM_PC24:
1840   case R_ARM_PLT32:
1841     return SignExtend64<26>(read32le(Buf) << 2);
1842   case R_ARM_THM_JUMP11:
1843     return SignExtend64<12>(read16le(Buf) << 1);
1844   case R_ARM_THM_JUMP19: {
1845     // Encoding T3: A = S:J2:J1:imm10:imm6:0
1846     uint16_t Hi = read16le(Buf);
1847     uint16_t Lo = read16le(Buf + 2);
1848     return SignExtend64<20>(((Hi & 0x0400) << 10) | // S
1849                             ((Lo & 0x0800) << 8) |  // J2
1850                             ((Lo & 0x2000) << 5) |  // J1
1851                             ((Hi & 0x003f) << 12) | // imm6
1852                             ((Lo & 0x07ff) << 1));  // imm11:0
1853   }
1854   case R_ARM_THM_CALL:
1855   case R_ARM_THM_JUMP24: {
1856     // Encoding B T4, BL T1, BLX T2: A = S:I1:I2:imm10:imm11:0
1857     // I1 = NOT(J1 EOR S), I2 = NOT(J2 EOR S)
1858     // FIXME: I1 and I2 require v6T2ops
1859     uint16_t Hi = read16le(Buf);
1860     uint16_t Lo = read16le(Buf + 2);
1861     return SignExtend64<24>(((Hi & 0x0400) << 14) |                    // S
1862                             (~((Lo ^ (Hi << 3)) << 10) & 0x00800000) | // I1
1863                             (~((Lo ^ (Hi << 1)) << 11) & 0x00400000) | // I2
1864                             ((Hi & 0x003ff) << 12) |                   // imm0
1865                             ((Lo & 0x007ff) << 1)); // imm11:0
1866   }
1867   // ELF for the ARM Architecture 4.6.1.1 the implicit addend for MOVW and
1868   // MOVT is in the range -32768 <= A < 32768
1869   case R_ARM_MOVW_ABS_NC:
1870   case R_ARM_MOVT_ABS:
1871   case R_ARM_MOVW_PREL_NC:
1872   case R_ARM_MOVT_PREL: {
1873     uint64_t Val = read32le(Buf) & 0x000f0fff;
1874     return SignExtend64<16>(((Val & 0x000f0000) >> 4) | (Val & 0x00fff));
1875   }
1876   case R_ARM_THM_MOVW_ABS_NC:
1877   case R_ARM_THM_MOVT_ABS:
1878   case R_ARM_THM_MOVW_PREL_NC:
1879   case R_ARM_THM_MOVT_PREL: {
1880     // Encoding T3: A = imm4:i:imm3:imm8
1881     uint16_t Hi = read16le(Buf);
1882     uint16_t Lo = read16le(Buf + 2);
1883     return SignExtend64<16>(((Hi & 0x000f) << 12) | // imm4
1884                             ((Hi & 0x0400) << 1) |  // i
1885                             ((Lo & 0x7000) >> 4) |  // imm3
1886                             (Lo & 0x00ff));         // imm8
1887   }
1888   }
1889 }
1890 
1891 bool ARMTargetInfo::isTlsLocalDynamicRel(uint32_t Type) const {
1892   return Type == R_ARM_TLS_LDO32 || Type == R_ARM_TLS_LDM32;
1893 }
1894 
1895 bool ARMTargetInfo::isTlsGlobalDynamicRel(uint32_t Type) const {
1896   return Type == R_ARM_TLS_GD32;
1897 }
1898 
1899 bool ARMTargetInfo::isTlsInitialExecRel(uint32_t Type) const {
1900   return Type == R_ARM_TLS_IE32;
1901 }
1902 
1903 template <class ELFT> MipsTargetInfo<ELFT>::MipsTargetInfo() {
1904   GotPltHeaderEntriesNum = 2;
1905   MaxPageSize = 65536;
1906   GotEntrySize = sizeof(typename ELFT::uint);
1907   GotPltEntrySize = sizeof(typename ELFT::uint);
1908   PltEntrySize = 16;
1909   PltHeaderSize = 32;
1910   CopyRel = R_MIPS_COPY;
1911   PltRel = R_MIPS_JUMP_SLOT;
1912   NeedsThunks = true;
1913   if (ELFT::Is64Bits) {
1914     RelativeRel = (R_MIPS_64 << 8) | R_MIPS_REL32;
1915     TlsGotRel = R_MIPS_TLS_TPREL64;
1916     TlsModuleIndexRel = R_MIPS_TLS_DTPMOD64;
1917     TlsOffsetRel = R_MIPS_TLS_DTPREL64;
1918   } else {
1919     RelativeRel = R_MIPS_REL32;
1920     TlsGotRel = R_MIPS_TLS_TPREL32;
1921     TlsModuleIndexRel = R_MIPS_TLS_DTPMOD32;
1922     TlsOffsetRel = R_MIPS_TLS_DTPREL32;
1923   }
1924 }
1925 
1926 template <class ELFT>
1927 RelExpr MipsTargetInfo<ELFT>::getRelExpr(uint32_t Type,
1928                                          const SymbolBody &S) const {
1929   // See comment in the calculateMipsRelChain.
1930   if (ELFT::Is64Bits || Config->MipsN32Abi)
1931     Type &= 0xff;
1932   switch (Type) {
1933   default:
1934     return R_ABS;
1935   case R_MIPS_JALR:
1936     return R_HINT;
1937   case R_MIPS_GPREL16:
1938   case R_MIPS_GPREL32:
1939     return R_MIPS_GOTREL;
1940   case R_MIPS_26:
1941     return R_PLT;
1942   case R_MIPS_HI16:
1943   case R_MIPS_LO16:
1944   case R_MIPS_GOT_OFST:
1945     // MIPS _gp_disp designates offset between start of function and 'gp'
1946     // pointer into GOT. __gnu_local_gp is equal to the current value of
1947     // the 'gp'. Therefore any relocations against them do not require
1948     // dynamic relocation.
1949     if (&S == ElfSym<ELFT>::MipsGpDisp)
1950       return R_PC;
1951     return R_ABS;
1952   case R_MIPS_PC32:
1953   case R_MIPS_PC16:
1954   case R_MIPS_PC19_S2:
1955   case R_MIPS_PC21_S2:
1956   case R_MIPS_PC26_S2:
1957   case R_MIPS_PCHI16:
1958   case R_MIPS_PCLO16:
1959     return R_PC;
1960   case R_MIPS_GOT16:
1961     if (S.isLocal())
1962       return R_MIPS_GOT_LOCAL_PAGE;
1963   // fallthrough
1964   case R_MIPS_CALL16:
1965   case R_MIPS_GOT_DISP:
1966   case R_MIPS_TLS_GOTTPREL:
1967     return R_MIPS_GOT_OFF;
1968   case R_MIPS_CALL_HI16:
1969   case R_MIPS_CALL_LO16:
1970   case R_MIPS_GOT_HI16:
1971   case R_MIPS_GOT_LO16:
1972     return R_MIPS_GOT_OFF32;
1973   case R_MIPS_GOT_PAGE:
1974     return R_MIPS_GOT_LOCAL_PAGE;
1975   case R_MIPS_TLS_GD:
1976     return R_MIPS_TLSGD;
1977   case R_MIPS_TLS_LDM:
1978     return R_MIPS_TLSLD;
1979   }
1980 }
1981 
1982 template <class ELFT>
1983 uint32_t MipsTargetInfo<ELFT>::getDynRel(uint32_t Type) const {
1984   if (Type == R_MIPS_32 || Type == R_MIPS_64)
1985     return RelativeRel;
1986   // Keep it going with a dummy value so that we can find more reloc errors.
1987   errorDynRel(Type);
1988   return R_MIPS_32;
1989 }
1990 
1991 template <class ELFT>
1992 bool MipsTargetInfo<ELFT>::isTlsLocalDynamicRel(uint32_t Type) const {
1993   return Type == R_MIPS_TLS_LDM;
1994 }
1995 
1996 template <class ELFT>
1997 bool MipsTargetInfo<ELFT>::isTlsGlobalDynamicRel(uint32_t Type) const {
1998   return Type == R_MIPS_TLS_GD;
1999 }
2000 
2001 template <class ELFT>
2002 void MipsTargetInfo<ELFT>::writeGotPlt(uint8_t *Buf, const SymbolBody &) const {
2003   write32<ELFT::TargetEndianness>(Buf, In<ELFT>::Plt->getVA());
2004 }
2005 
2006 template <endianness E, uint8_t BSIZE, uint8_t SHIFT>
2007 static int64_t getPcRelocAddend(const uint8_t *Loc) {
2008   uint32_t Instr = read32<E>(Loc);
2009   uint32_t Mask = 0xffffffff >> (32 - BSIZE);
2010   return SignExtend64<BSIZE + SHIFT>((Instr & Mask) << SHIFT);
2011 }
2012 
2013 template <endianness E, uint8_t BSIZE, uint8_t SHIFT>
2014 static void applyMipsPcReloc(uint8_t *Loc, uint32_t Type, uint64_t V) {
2015   uint32_t Mask = 0xffffffff >> (32 - BSIZE);
2016   uint32_t Instr = read32<E>(Loc);
2017   if (SHIFT > 0)
2018     checkAlignment<(1 << SHIFT)>(V, Type);
2019   checkInt<BSIZE + SHIFT>(V, Type);
2020   write32<E>(Loc, (Instr & ~Mask) | ((V >> SHIFT) & Mask));
2021 }
2022 
2023 template <endianness E> static void writeMipsHi16(uint8_t *Loc, uint64_t V) {
2024   uint32_t Instr = read32<E>(Loc);
2025   uint16_t Res = ((V + 0x8000) >> 16) & 0xffff;
2026   write32<E>(Loc, (Instr & 0xffff0000) | Res);
2027 }
2028 
2029 template <endianness E> static void writeMipsHigher(uint8_t *Loc, uint64_t V) {
2030   uint32_t Instr = read32<E>(Loc);
2031   uint16_t Res = ((V + 0x80008000) >> 32) & 0xffff;
2032   write32<E>(Loc, (Instr & 0xffff0000) | Res);
2033 }
2034 
2035 template <endianness E> static void writeMipsHighest(uint8_t *Loc, uint64_t V) {
2036   uint32_t Instr = read32<E>(Loc);
2037   uint16_t Res = ((V + 0x800080008000) >> 48) & 0xffff;
2038   write32<E>(Loc, (Instr & 0xffff0000) | Res);
2039 }
2040 
2041 template <endianness E> static void writeMipsLo16(uint8_t *Loc, uint64_t V) {
2042   uint32_t Instr = read32<E>(Loc);
2043   write32<E>(Loc, (Instr & 0xffff0000) | (V & 0xffff));
2044 }
2045 
2046 template <class ELFT> static bool isMipsR6() {
2047   const auto &FirstObj = cast<ELFFileBase<ELFT>>(*Config->FirstElf);
2048   uint32_t Arch = FirstObj.getObj().getHeader()->e_flags & EF_MIPS_ARCH;
2049   return Arch == EF_MIPS_ARCH_32R6 || Arch == EF_MIPS_ARCH_64R6;
2050 }
2051 
2052 template <class ELFT>
2053 void MipsTargetInfo<ELFT>::writePltHeader(uint8_t *Buf) const {
2054   const endianness E = ELFT::TargetEndianness;
2055   if (Config->MipsN32Abi) {
2056     write32<E>(Buf, 0x3c0e0000);      // lui   $14, %hi(&GOTPLT[0])
2057     write32<E>(Buf + 4, 0x8dd90000);  // lw    $25, %lo(&GOTPLT[0])($14)
2058     write32<E>(Buf + 8, 0x25ce0000);  // addiu $14, $14, %lo(&GOTPLT[0])
2059     write32<E>(Buf + 12, 0x030ec023); // subu  $24, $24, $14
2060   } else {
2061     write32<E>(Buf, 0x3c1c0000);      // lui   $28, %hi(&GOTPLT[0])
2062     write32<E>(Buf + 4, 0x8f990000);  // lw    $25, %lo(&GOTPLT[0])($28)
2063     write32<E>(Buf + 8, 0x279c0000);  // addiu $28, $28, %lo(&GOTPLT[0])
2064     write32<E>(Buf + 12, 0x031cc023); // subu  $24, $24, $28
2065   }
2066   write32<E>(Buf + 16, 0x03e07825); // move  $15, $31
2067   write32<E>(Buf + 20, 0x0018c082); // srl   $24, $24, 2
2068   write32<E>(Buf + 24, 0x0320f809); // jalr  $25
2069   write32<E>(Buf + 28, 0x2718fffe); // subu  $24, $24, 2
2070   uint64_t Got = In<ELFT>::GotPlt->getVA();
2071   writeMipsHi16<E>(Buf, Got);
2072   writeMipsLo16<E>(Buf + 4, Got);
2073   writeMipsLo16<E>(Buf + 8, Got);
2074 }
2075 
2076 template <class ELFT>
2077 void MipsTargetInfo<ELFT>::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
2078                                     uint64_t PltEntryAddr, int32_t Index,
2079                                     unsigned RelOff) const {
2080   const endianness E = ELFT::TargetEndianness;
2081   write32<E>(Buf, 0x3c0f0000);     // lui   $15, %hi(.got.plt entry)
2082   write32<E>(Buf + 4, 0x8df90000); // l[wd] $25, %lo(.got.plt entry)($15)
2083                                    // jr    $25
2084   write32<E>(Buf + 8, isMipsR6<ELFT>() ? 0x03200009 : 0x03200008);
2085   write32<E>(Buf + 12, 0x25f80000); // addiu $24, $15, %lo(.got.plt entry)
2086   writeMipsHi16<E>(Buf, GotEntryAddr);
2087   writeMipsLo16<E>(Buf + 4, GotEntryAddr);
2088   writeMipsLo16<E>(Buf + 12, GotEntryAddr);
2089 }
2090 
2091 template <class ELFT>
2092 RelExpr MipsTargetInfo<ELFT>::getThunkExpr(RelExpr Expr, uint32_t Type,
2093                                            const InputFile &File,
2094                                            const SymbolBody &S) const {
2095   // Any MIPS PIC code function is invoked with its address in register $t9.
2096   // So if we have a branch instruction from non-PIC code to the PIC one
2097   // we cannot make the jump directly and need to create a small stubs
2098   // to save the target function address.
2099   // See page 3-38 ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
2100   if (Type != R_MIPS_26)
2101     return Expr;
2102   auto *F = dyn_cast<ELFFileBase<ELFT>>(&File);
2103   if (!F)
2104     return Expr;
2105   // If current file has PIC code, LA25 stub is not required.
2106   if (F->getObj().getHeader()->e_flags & EF_MIPS_PIC)
2107     return Expr;
2108   auto *D = dyn_cast<DefinedRegular<ELFT>>(&S);
2109   // LA25 is required if target file has PIC code
2110   // or target symbol is a PIC symbol.
2111   return D && D->isMipsPIC() ? R_THUNK_ABS : Expr;
2112 }
2113 
2114 template <class ELFT>
2115 uint64_t MipsTargetInfo<ELFT>::getImplicitAddend(const uint8_t *Buf,
2116                                                  uint32_t Type) const {
2117   const endianness E = ELFT::TargetEndianness;
2118   switch (Type) {
2119   default:
2120     return 0;
2121   case R_MIPS_32:
2122   case R_MIPS_GPREL32:
2123   case R_MIPS_TLS_DTPREL32:
2124   case R_MIPS_TLS_TPREL32:
2125     return read32<E>(Buf);
2126   case R_MIPS_26:
2127     // FIXME (simon): If the relocation target symbol is not a PLT entry
2128     // we should use another expression for calculation:
2129     // ((A << 2) | (P & 0xf0000000)) >> 2
2130     return SignExtend64<28>((read32<E>(Buf) & 0x3ffffff) << 2);
2131   case R_MIPS_GPREL16:
2132   case R_MIPS_LO16:
2133   case R_MIPS_PCLO16:
2134   case R_MIPS_TLS_DTPREL_HI16:
2135   case R_MIPS_TLS_DTPREL_LO16:
2136   case R_MIPS_TLS_TPREL_HI16:
2137   case R_MIPS_TLS_TPREL_LO16:
2138     return SignExtend64<16>(read32<E>(Buf));
2139   case R_MIPS_PC16:
2140     return getPcRelocAddend<E, 16, 2>(Buf);
2141   case R_MIPS_PC19_S2:
2142     return getPcRelocAddend<E, 19, 2>(Buf);
2143   case R_MIPS_PC21_S2:
2144     return getPcRelocAddend<E, 21, 2>(Buf);
2145   case R_MIPS_PC26_S2:
2146     return getPcRelocAddend<E, 26, 2>(Buf);
2147   case R_MIPS_PC32:
2148     return getPcRelocAddend<E, 32, 0>(Buf);
2149   }
2150 }
2151 
2152 static std::pair<uint32_t, uint64_t> calculateMipsRelChain(uint32_t Type,
2153                                                            uint64_t Val) {
2154   // MIPS N64 ABI packs multiple relocations into the single relocation
2155   // record. In general, all up to three relocations can have arbitrary
2156   // types. In fact, Clang and GCC uses only a few combinations. For now,
2157   // we support two of them. That is allow to pass at least all LLVM
2158   // test suite cases.
2159   // <any relocation> / R_MIPS_SUB / R_MIPS_HI16 | R_MIPS_LO16
2160   // <any relocation> / R_MIPS_64 / R_MIPS_NONE
2161   // The first relocation is a 'real' relocation which is calculated
2162   // using the corresponding symbol's value. The second and the third
2163   // relocations used to modify result of the first one: extend it to
2164   // 64-bit, extract high or low part etc. For details, see part 2.9 Relocation
2165   // at the https://dmz-portal.mips.com/mw/images/8/82/007-4658-001.pdf
2166   uint32_t Type2 = (Type >> 8) & 0xff;
2167   uint32_t Type3 = (Type >> 16) & 0xff;
2168   if (Type2 == R_MIPS_NONE && Type3 == R_MIPS_NONE)
2169     return std::make_pair(Type, Val);
2170   if (Type2 == R_MIPS_64 && Type3 == R_MIPS_NONE)
2171     return std::make_pair(Type2, Val);
2172   if (Type2 == R_MIPS_SUB && (Type3 == R_MIPS_HI16 || Type3 == R_MIPS_LO16))
2173     return std::make_pair(Type3, -Val);
2174   error("unsupported relocations combination " + Twine(Type));
2175   return std::make_pair(Type & 0xff, Val);
2176 }
2177 
2178 template <class ELFT>
2179 void MipsTargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint32_t Type,
2180                                        uint64_t Val) const {
2181   const endianness E = ELFT::TargetEndianness;
2182   // Thread pointer and DRP offsets from the start of TLS data area.
2183   // https://www.linux-mips.org/wiki/NPTL
2184   if (Type == R_MIPS_TLS_DTPREL_HI16 || Type == R_MIPS_TLS_DTPREL_LO16 ||
2185       Type == R_MIPS_TLS_DTPREL32 || Type == R_MIPS_TLS_DTPREL64)
2186     Val -= 0x8000;
2187   else if (Type == R_MIPS_TLS_TPREL_HI16 || Type == R_MIPS_TLS_TPREL_LO16 ||
2188            Type == R_MIPS_TLS_TPREL32 || Type == R_MIPS_TLS_TPREL64)
2189     Val -= 0x7000;
2190   if (ELFT::Is64Bits || Config->MipsN32Abi)
2191     std::tie(Type, Val) = calculateMipsRelChain(Type, Val);
2192   switch (Type) {
2193   case R_MIPS_32:
2194   case R_MIPS_GPREL32:
2195   case R_MIPS_TLS_DTPREL32:
2196   case R_MIPS_TLS_TPREL32:
2197     write32<E>(Loc, Val);
2198     break;
2199   case R_MIPS_64:
2200   case R_MIPS_TLS_DTPREL64:
2201   case R_MIPS_TLS_TPREL64:
2202     write64<E>(Loc, Val);
2203     break;
2204   case R_MIPS_26:
2205     write32<E>(Loc, (read32<E>(Loc) & ~0x3ffffff) | ((Val >> 2) & 0x3ffffff));
2206     break;
2207   case R_MIPS_GOT_DISP:
2208   case R_MIPS_GOT_PAGE:
2209   case R_MIPS_GOT16:
2210   case R_MIPS_GPREL16:
2211   case R_MIPS_TLS_GD:
2212   case R_MIPS_TLS_LDM:
2213     checkInt<16>(Val, Type);
2214   // fallthrough
2215   case R_MIPS_CALL16:
2216   case R_MIPS_CALL_LO16:
2217   case R_MIPS_GOT_LO16:
2218   case R_MIPS_GOT_OFST:
2219   case R_MIPS_LO16:
2220   case R_MIPS_PCLO16:
2221   case R_MIPS_TLS_DTPREL_LO16:
2222   case R_MIPS_TLS_GOTTPREL:
2223   case R_MIPS_TLS_TPREL_LO16:
2224     writeMipsLo16<E>(Loc, Val);
2225     break;
2226   case R_MIPS_CALL_HI16:
2227   case R_MIPS_GOT_HI16:
2228   case R_MIPS_HI16:
2229   case R_MIPS_PCHI16:
2230   case R_MIPS_TLS_DTPREL_HI16:
2231   case R_MIPS_TLS_TPREL_HI16:
2232     writeMipsHi16<E>(Loc, Val);
2233     break;
2234   case R_MIPS_HIGHER:
2235     writeMipsHigher<E>(Loc, Val);
2236     break;
2237   case R_MIPS_HIGHEST:
2238     writeMipsHighest<E>(Loc, Val);
2239     break;
2240   case R_MIPS_JALR:
2241     // Ignore this optimization relocation for now
2242     break;
2243   case R_MIPS_PC16:
2244     applyMipsPcReloc<E, 16, 2>(Loc, Type, Val);
2245     break;
2246   case R_MIPS_PC19_S2:
2247     applyMipsPcReloc<E, 19, 2>(Loc, Type, Val);
2248     break;
2249   case R_MIPS_PC21_S2:
2250     applyMipsPcReloc<E, 21, 2>(Loc, Type, Val);
2251     break;
2252   case R_MIPS_PC26_S2:
2253     applyMipsPcReloc<E, 26, 2>(Loc, Type, Val);
2254     break;
2255   case R_MIPS_PC32:
2256     applyMipsPcReloc<E, 32, 0>(Loc, Type, Val);
2257     break;
2258   default:
2259     fatal("unrecognized reloc " + Twine(Type));
2260   }
2261 }
2262 
2263 template <class ELFT>
2264 bool MipsTargetInfo<ELFT>::usesOnlyLowPageBits(uint32_t Type) const {
2265   return Type == R_MIPS_LO16 || Type == R_MIPS_GOT_OFST;
2266 }
2267 }
2268 }
2269