RuntimeDyldMachO.cpp revision 61425c0a7f4e3608a85f7bbf254cd052a15b7446 
1//===-- RuntimeDyldMachO.cpp - Run-time dynamic linker for MC-JIT ------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Implementation of the MC-JIT runtime dynamic linker.
11//
12//===----------------------------------------------------------------------===//
13
14#define DEBUG_TYPE "dyld"
15#include "llvm/ADT/OwningPtr.h"
16#include "llvm/ADT/StringRef.h"
17#include "llvm/ADT/STLExtras.h"
18#include "RuntimeDyldImpl.h"
19using namespace llvm;
20using namespace llvm::object;
21
22namespace llvm {
23
24bool RuntimeDyldMachO::
25resolveRelocation(uint8_t *Address, uint64_t Value, bool isPCRel,
26                  unsigned Type, unsigned Size, int64_t Addend) {
27  // This just dispatches to the proper target specific routine.
28  switch (CPUType) {
29  default: assert(0 && "Unsupported CPU type!");
30  case mach::CTM_x86_64:
31    return resolveX86_64Relocation((uintptr_t)Address, (uintptr_t)Value,
32                                   isPCRel, Type, Size, Addend);
33  case mach::CTM_ARM:
34    return resolveARMRelocation((uintptr_t)Address, (uintptr_t)Value,
35                                isPCRel, Type, Size, Addend);
36  }
37  llvm_unreachable("");
38}
39
40bool RuntimeDyldMachO::
41resolveX86_64Relocation(uintptr_t Address, uintptr_t Value, bool isPCRel,
42                        unsigned Type, unsigned Size, int64_t Addend) {
43  // If the relocation is PC-relative, the value to be encoded is the
44  // pointer difference.
45  if (isPCRel)
46    // FIXME: It seems this value needs to be adjusted by 4 for an effective PC
47    // address. Is that expected? Only for branches, perhaps?
48    Value -= Address + 4;
49
50  switch(Type) {
51  default:
52    llvm_unreachable("Invalid relocation type!");
53  case macho::RIT_X86_64_Unsigned:
54  case macho::RIT_X86_64_Branch: {
55    // Mask in the target value a byte at a time (we don't have an alignment
56    // guarantee for the target address, so this is safest).
57    uint8_t *p = (uint8_t*)Address;
58    for (unsigned i = 0; i < Size; ++i) {
59      *p++ = (uint8_t)Value;
60      Value >>= 8;
61    }
62    return false;
63  }
64  case macho::RIT_X86_64_Signed:
65  case macho::RIT_X86_64_GOTLoad:
66  case macho::RIT_X86_64_GOT:
67  case macho::RIT_X86_64_Subtractor:
68  case macho::RIT_X86_64_Signed1:
69  case macho::RIT_X86_64_Signed2:
70  case macho::RIT_X86_64_Signed4:
71  case macho::RIT_X86_64_TLV:
72    return Error("Relocation type not implemented yet!");
73  }
74  return false;
75}
76
77bool RuntimeDyldMachO::
78resolveARMRelocation(uintptr_t Address, uintptr_t Value, bool isPCRel,
79                     unsigned Type, unsigned Size, int64_t Addend) {
80  // If the relocation is PC-relative, the value to be encoded is the
81  // pointer difference.
82  if (isPCRel) {
83    Value -= Address;
84    // ARM PCRel relocations have an effective-PC offset of two instructions
85    // (four bytes in Thumb mode, 8 bytes in ARM mode).
86    // FIXME: For now, assume ARM mode.
87    Value -= 8;
88  }
89
90  switch(Type) {
91  default:
92    llvm_unreachable("Invalid relocation type!");
93  case macho::RIT_Vanilla: {
94    llvm_unreachable("Invalid relocation type!");
95    // Mask in the target value a byte at a time (we don't have an alignment
96    // guarantee for the target address, so this is safest).
97    uint8_t *p = (uint8_t*)Address;
98    for (unsigned i = 0; i < Size; ++i) {
99      *p++ = (uint8_t)Value;
100      Value >>= 8;
101    }
102    break;
103  }
104  case macho::RIT_ARM_Branch24Bit: {
105    // Mask the value into the target address. We know instructions are
106    // 32-bit aligned, so we can do it all at once.
107    uint32_t *p = (uint32_t*)Address;
108    // The low two bits of the value are not encoded.
109    Value >>= 2;
110    // Mask the value to 24 bits.
111    Value &= 0xffffff;
112    // FIXME: If the destination is a Thumb function (and the instruction
113    // is a non-predicated BL instruction), we need to change it to a BLX
114    // instruction instead.
115
116    // Insert the value into the instruction.
117    *p = (*p & ~0xffffff) | Value;
118    break;
119  }
120  case macho::RIT_ARM_ThumbBranch22Bit:
121  case macho::RIT_ARM_ThumbBranch32Bit:
122  case macho::RIT_ARM_Half:
123  case macho::RIT_ARM_HalfDifference:
124  case macho::RIT_Pair:
125  case macho::RIT_Difference:
126  case macho::RIT_ARM_LocalDifference:
127  case macho::RIT_ARM_PreboundLazyPointer:
128    return Error("Relocation type not implemented yet!");
129  }
130  return false;
131}
132
133bool RuntimeDyldMachO::
134loadSegment32(const MachOObject *Obj,
135              const MachOObject::LoadCommandInfo *SegmentLCI,
136              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
137  // FIXME: This should really be combined w/ loadSegment64. Templatized
138  // function on the 32/64 datatypes maybe?
139  InMemoryStruct<macho::SegmentLoadCommand> SegmentLC;
140  Obj->ReadSegmentLoadCommand(*SegmentLCI, SegmentLC);
141  if (!SegmentLC)
142    return Error("unable to load segment load command");
143
144
145  SmallVector<unsigned, 16> SectionMap;
146  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
147    InMemoryStruct<macho::Section> Sect;
148    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
149    if (!Sect)
150      return Error("unable to load section: '" + Twine(SectNum) + "'");
151
152    // Allocate memory via the MM for the section.
153    uint8_t *Buffer;
154    uint32_t SectionID = Sections.size();
155    if (Sect->Flags != 0x80000400)
156      Buffer = MemMgr->allocateCodeSection(Sect->Size, Sect->Align, SectionID);
157    else
158      Buffer = MemMgr->allocateDataSection(Sect->Size, Sect->Align, SectionID);
159
160    DEBUG(dbgs() << "Loading "
161                 << ((Sect->Flags == 0x80000400) ? "text" : "data")
162                 << " (ID #" << SectionID << ")"
163                 << " '" << Sect->SegmentName << ","
164                 << Sect->Name << "' of size " << Sect->Size
165                 << " to address " << Buffer << ".\n");
166
167    // Copy the payload from the object file into the allocated buffer.
168    uint8_t *Base = (uint8_t*)Obj->getData(SegmentLC->FileOffset,
169                                           SegmentLC->FileSize).data();
170    memcpy(Buffer, Base + Sect->Address, Sect->Size);
171
172    // Remember what got allocated for this SectionID.
173    Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
174
175    // By default, the load address of a section is its memory buffer.
176    SectionLoadAddress.push_back((uint64_t)Buffer);
177
178    // Keep a map of object file section numbers to corresponding SectionIDs
179    // while processing the file.
180    SectionMap.push_back(SectionID);
181  }
182
183  // Process the symbol table.
184  SmallVector<StringRef, 64> SymbolNames;
185  processSymbols32(Obj, SectionMap, SymbolNames, SymtabLC);
186
187  // Process the relocations for each section we're loading.
188  Relocations.grow(Relocations.size() + SegmentLC->NumSections);
189  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
190    InMemoryStruct<macho::Section> Sect;
191    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
192    if (!Sect)
193      return Error("unable to load section: '" + Twine(SectNum) + "'");
194    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
195      InMemoryStruct<macho::RelocationEntry> RE;
196      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
197      if (RE->Word0 & macho::RF_Scattered)
198        return Error("NOT YET IMPLEMENTED: scattered relocations.");
199      // Word0 of the relocation is the offset into the section where the
200      // relocation should be applied. We need to translate that into an
201      // offset into a function since that's our atom.
202      uint32_t Offset = RE->Word0;
203      bool isExtern = (RE->Word1 >> 27) & 1;
204
205      // FIXME: Get the relocation addend from the target address.
206      // FIXME: VERY imporant for internal relocations.
207
208      // Figure out the source symbol of the relocation. If isExtern is true,
209      // this relocation references the symbol table, otherwise it references
210      // a section in the same object, numbered from 1 through NumSections
211      // (SectionBases is [0, NumSections-1]).
212      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
213      if (!isExtern) {
214        assert(SourceNum > 0 && "Invalid relocation section number!");
215        unsigned SectionID = SectionMap[SourceNum - 1];
216        unsigned TargetID = SectionMap[SectNum];
217        DEBUG(dbgs() << "Internal relocation at Section #"
218                     << TargetID << " + " << Offset
219                     << " from Section #"
220                     << SectionID << " (Word1: "
221                     << format("0x%x", RE->Word1) << ")\n");
222
223        // Store the relocation information. It will get resolved when
224        // the section addresses are assigned.
225        Relocations[SectionID].push_back(RelocationEntry(TargetID,
226                                                         Offset,
227                                                         RE->Word1,
228                                                         0 /*Addend*/));
229      } else {
230        StringRef SourceName = SymbolNames[SourceNum];
231
232        // Now store the relocation information. Associate it with the source
233        // symbol. Just add it to the unresolved list and let the general
234        // path post-load resolve it if we know where the symbol is.
235        UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
236                                                                    Offset,
237                                                                    RE->Word1,
238                                                                 0 /*Addend*/));
239        DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
240              << " from '" << SourceName << "(Word1: "
241              << format("0x%x", RE->Word1) << ")\n");
242      }
243    }
244  }
245
246  // Resolve the addresses of any symbols that were defined in this segment.
247  for (int i = 0, e = SymbolNames.size(); i != e; ++i)
248    resolveSymbol(SymbolNames[i]);
249
250  return false;
251}
252
253
254bool RuntimeDyldMachO::
255loadSegment64(const MachOObject *Obj,
256              const MachOObject::LoadCommandInfo *SegmentLCI,
257              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
258  InMemoryStruct<macho::Segment64LoadCommand> Segment64LC;
259  Obj->ReadSegment64LoadCommand(*SegmentLCI, Segment64LC);
260  if (!Segment64LC)
261    return Error("unable to load segment load command");
262
263
264  SmallVector<unsigned, 16> SectionMap;
265  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
266    InMemoryStruct<macho::Section64> Sect;
267    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
268    if (!Sect)
269      return Error("unable to load section: '" + Twine(SectNum) + "'");
270
271    // Allocate memory via the MM for the section.
272    uint8_t *Buffer;
273    uint32_t SectionID = Sections.size();
274    if (Sect->Flags != 0x80000400)
275      Buffer = MemMgr->allocateCodeSection(Sect->Size, Sect->Align, SectionID);
276    else
277      Buffer = MemMgr->allocateDataSection(Sect->Size, Sect->Align, SectionID);
278
279    DEBUG(dbgs() << "Loading "
280                 << ((Sect->Flags == 0x80000400) ? "text" : "data")
281                 << " (ID #" << SectionID << ")"
282                 << " '" << Sect->SegmentName << ","
283                 << Sect->Name << "' of size " << Sect->Size
284                 << " to address " << Buffer << ".\n");
285
286    // Copy the payload from the object file into the allocated buffer.
287    uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
288                                           Segment64LC->FileSize).data();
289    memcpy(Buffer, Base + Sect->Address, Sect->Size);
290
291    // Remember what got allocated for this SectionID.
292    Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
293
294    // By default, the load address of a section is its memory buffer.
295    SectionLoadAddress.push_back((uint64_t)Buffer);
296
297    // Keep a map of object file section numbers to corresponding SectionIDs
298    // while processing the file.
299    SectionMap.push_back(SectionID);
300  }
301
302  // Process the symbol table.
303  SmallVector<StringRef, 64> SymbolNames;
304  processSymbols64(Obj, SectionMap, SymbolNames, SymtabLC);
305
306  // Process the relocations for each section we're loading.
307  Relocations.grow(Relocations.size() + Segment64LC->NumSections);
308  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
309    InMemoryStruct<macho::Section64> Sect;
310    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
311    if (!Sect)
312      return Error("unable to load section: '" + Twine(SectNum) + "'");
313    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
314      InMemoryStruct<macho::RelocationEntry> RE;
315      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
316      if (RE->Word0 & macho::RF_Scattered)
317        return Error("NOT YET IMPLEMENTED: scattered relocations.");
318      // Word0 of the relocation is the offset into the section where the
319      // relocation should be applied. We need to translate that into an
320      // offset into a function since that's our atom.
321      uint32_t Offset = RE->Word0;
322      bool isExtern = (RE->Word1 >> 27) & 1;
323
324      // FIXME: Get the relocation addend from the target address.
325      // FIXME: VERY imporant for internal relocations.
326
327      // Figure out the source symbol of the relocation. If isExtern is true,
328      // this relocation references the symbol table, otherwise it references
329      // a section in the same object, numbered from 1 through NumSections
330      // (SectionBases is [0, NumSections-1]).
331      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
332      if (!isExtern) {
333        assert(SourceNum > 0 && "Invalid relocation section number!");
334        unsigned SectionID = SectionMap[SourceNum - 1];
335        unsigned TargetID = SectionMap[SectNum];
336        DEBUG(dbgs() << "Internal relocation at Section #"
337                     << TargetID << " + " << Offset
338                     << " from Section #"
339                     << SectionID << " (Word1: "
340                     << format("0x%x", RE->Word1) << ")\n");
341
342        // Store the relocation information. It will get resolved when
343        // the section addresses are assigned.
344        Relocations[SectionID].push_back(RelocationEntry(TargetID,
345                                                         Offset,
346                                                         RE->Word1,
347                                                         0 /*Addend*/));
348      } else {
349        StringRef SourceName = SymbolNames[SourceNum];
350
351        // Now store the relocation information. Associate it with the source
352        // symbol. Just add it to the unresolved list and let the general
353        // path post-load resolve it if we know where the symbol is.
354        UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
355                                                                    Offset,
356                                                                    RE->Word1,
357                                                                 0 /*Addend*/));
358        DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
359              << " from '" << SourceName << "(Word1: "
360              << format("0x%x", RE->Word1) << ")\n");
361      }
362    }
363  }
364
365  // Resolve the addresses of any symbols that were defined in this segment.
366  for (int i = 0, e = SymbolNames.size(); i != e; ++i)
367    resolveSymbol(SymbolNames[i]);
368
369  return false;
370}
371
372bool RuntimeDyldMachO::
373processSymbols32(const MachOObject *Obj,
374                 SmallVectorImpl<unsigned> &SectionMap,
375                 SmallVectorImpl<StringRef> &SymbolNames,
376                 const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
377  // FIXME: Combine w/ processSymbols64. Factor 64/32 datatype and such.
378  for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
379    InMemoryStruct<macho::SymbolTableEntry> STE;
380    Obj->ReadSymbolTableEntry(SymtabLC->SymbolTableOffset, i, STE);
381    if (!STE)
382      return Error("unable to read symbol: '" + Twine(i) + "'");
383    // Get the symbol name.
384    StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
385    SymbolNames.push_back(Name);
386
387    // FIXME: Check the symbol type and flags.
388    if (STE->Type != 0xF)  // external, defined in this segment.
389      continue;
390    // Flags in the upper nibble we don't care about.
391    if ((STE->Flags & 0xf) != 0x0)
392      continue;
393
394    // Remember the symbol.
395    uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
396    SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
397
398    DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
399                 << (getSectionAddress(SectionID) + STE->Value)
400                 << "\n");
401  }
402  return false;
403}
404
405bool RuntimeDyldMachO::
406processSymbols64(const MachOObject *Obj,
407                 SmallVectorImpl<unsigned> &SectionMap,
408                 SmallVectorImpl<StringRef> &SymbolNames,
409                 const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
410  for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
411    InMemoryStruct<macho::Symbol64TableEntry> STE;
412    Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE);
413    if (!STE)
414      return Error("unable to read symbol: '" + Twine(i) + "'");
415    // Get the symbol name.
416    StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
417    SymbolNames.push_back(Name);
418
419    // FIXME: Check the symbol type and flags.
420    if (STE->Type != 0xF)  // external, defined in this segment.
421      continue;
422    // Flags in the upper nibble we don't care about.
423    if ((STE->Flags & 0xf) != 0x0)
424      continue;
425
426    // Remember the symbol.
427    uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
428    SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
429
430    DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
431                 << (getSectionAddress(SectionID) + STE->Value)
432                 << "\n");
433  }
434  return false;
435}
436
437// resolveSymbol - Resolve any relocations to the specified symbol if
438// we know where it lives.
439void RuntimeDyldMachO::resolveSymbol(StringRef Name) {
440  StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
441  if (Loc == SymbolTable.end())
442    return;
443
444  RelocationList &Relocs = UnresolvedRelocations[Name];
445  DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
446  for (int i = 0, e = Relocs.size(); i != e; ++i) {
447    // Change the relocation to be section relative rather than symbol
448    // relative and move it to the resolved relocation list.
449    RelocationEntry Entry = Relocs[i];
450    Entry.Addend += Loc->second.second;
451    Relocations[Loc->second.first].push_back(Entry);
452  }
453  // FIXME: Keep a worklist of the relocations we've added so that we can
454  // resolve more selectively later.
455  Relocs.clear();
456}
457
458bool RuntimeDyldMachO::loadObject(MemoryBuffer *InputBuffer) {
459  // If the linker is in an error state, don't do anything.
460  if (hasError())
461    return true;
462  // Load the Mach-O wrapper object.
463  std::string ErrorStr;
464  OwningPtr<MachOObject> Obj(
465    MachOObject::LoadFromBuffer(InputBuffer, &ErrorStr));
466  if (!Obj)
467    return Error("unable to load object: '" + ErrorStr + "'");
468
469  // Get the CPU type information from the header.
470  const macho::Header &Header = Obj->getHeader();
471
472  // FIXME: Error checking that the loaded object is compatible with
473  //        the system we're running on.
474  CPUType = Header.CPUType;
475  CPUSubtype = Header.CPUSubtype;
476
477  // Validate that the load commands match what we expect.
478  const MachOObject::LoadCommandInfo *SegmentLCI = 0, *SymtabLCI = 0,
479    *DysymtabLCI = 0;
480  for (unsigned i = 0; i != Header.NumLoadCommands; ++i) {
481    const MachOObject::LoadCommandInfo &LCI = Obj->getLoadCommandInfo(i);
482    switch (LCI.Command.Type) {
483    case macho::LCT_Segment:
484    case macho::LCT_Segment64:
485      if (SegmentLCI)
486        return Error("unexpected input object (multiple segments)");
487      SegmentLCI = &LCI;
488      break;
489    case macho::LCT_Symtab:
490      if (SymtabLCI)
491        return Error("unexpected input object (multiple symbol tables)");
492      SymtabLCI = &LCI;
493      break;
494    case macho::LCT_Dysymtab:
495      if (DysymtabLCI)
496        return Error("unexpected input object (multiple symbol tables)");
497      DysymtabLCI = &LCI;
498      break;
499    default:
500      return Error("unexpected input object (unexpected load command");
501    }
502  }
503
504  if (!SymtabLCI)
505    return Error("no symbol table found in object");
506  if (!SegmentLCI)
507    return Error("no segments found in object");
508
509  // Read and register the symbol table data.
510  InMemoryStruct<macho::SymtabLoadCommand> SymtabLC;
511  Obj->ReadSymtabLoadCommand(*SymtabLCI, SymtabLC);
512  if (!SymtabLC)
513    return Error("unable to load symbol table load command");
514  Obj->RegisterStringTable(*SymtabLC);
515
516  // Read the dynamic link-edit information, if present (not present in static
517  // objects).
518  if (DysymtabLCI) {
519    InMemoryStruct<macho::DysymtabLoadCommand> DysymtabLC;
520    Obj->ReadDysymtabLoadCommand(*DysymtabLCI, DysymtabLC);
521    if (!DysymtabLC)
522      return Error("unable to load dynamic link-exit load command");
523
524    // FIXME: We don't support anything interesting yet.
525//    if (DysymtabLC->LocalSymbolsIndex != 0)
526//      return Error("NOT YET IMPLEMENTED: local symbol entries");
527//    if (DysymtabLC->ExternalSymbolsIndex != 0)
528//      return Error("NOT YET IMPLEMENTED: non-external symbol entries");
529//    if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
530//      return Error("NOT YET IMPLEMENTED: undefined symbol entries");
531  }
532
533  // Load the segment load command.
534  if (SegmentLCI->Command.Type == macho::LCT_Segment) {
535    if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC))
536      return true;
537  } else {
538    if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC))
539      return true;
540  }
541
542  // Assign the addresses of the sections from the object so that any
543  // relocations to them get set properly.
544  // FIXME: This is done directly from the client at the moment. We should
545  // default the values to the local storage, at least when the target arch
546  // is the same as the host arch.
547
548  return false;
549}
550
551// Assign an address to a symbol name and resolve all the relocations
552// associated with it.
553void RuntimeDyldMachO::reassignSectionAddress(unsigned SectionID,
554                                              uint64_t Addr) {
555  // The address to use for relocation resolution is not
556  // the address of the local section buffer. We must be doing
557  // a remote execution environment of some sort. Re-apply any
558  // relocations referencing this section with the given address.
559  //
560  // Addr is a uint64_t because we can't assume the pointer width
561  // of the target is the same as that of the host. Just use a generic
562  // "big enough" type.
563
564  SectionLoadAddress[SectionID] = Addr;
565
566  RelocationList &Relocs = Relocations[SectionID];
567  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
568    RelocationEntry &RE = Relocs[i];
569    uint8_t *Target = (uint8_t*)Sections[RE.SectionID].base() + RE.Offset;
570    bool isPCRel = (RE.Data >> 24) & 1;
571    unsigned Type = (RE.Data >> 28) & 0xf;
572    unsigned Size = 1 << ((RE.Data >> 25) & 3);
573
574    DEBUG(dbgs() << "Resolving relocation at Section #" << RE.SectionID
575          << " + " << RE.Offset << " (" << format("%p", Target) << ")"
576          << " from Section #" << SectionID << " (" << format("%p", Addr) << ")"
577          << "(" << (isPCRel ? "pcrel" : "absolute")
578          << ", type: " << Type << ", Size: " << Size << ", Addend: "
579          << RE.Addend << ").\n");
580
581    resolveRelocation(Target, Addr, isPCRel, Type, Size, RE.Addend);
582  }
583}
584
585bool RuntimeDyldMachO::isKnownFormat(const MemoryBuffer *InputBuffer) {
586  StringRef Magic = InputBuffer->getBuffer().slice(0, 4);
587  if (Magic == "\xFE\xED\xFA\xCE") return true;
588  if (Magic == "\xCE\xFA\xED\xFE") return true;
589  if (Magic == "\xFE\xED\xFA\xCF") return true;
590  if (Magic == "\xCF\xFA\xED\xFE") return true;
591  return false;
592}
593
594} // end namespace llvm
595