1 //===-- RuntimeDyldMachO.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Implementation of the MC-JIT runtime dynamic linker.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "dyld"
15 #include "RuntimeDyldMachO.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/StringRef.h"
19 using namespace llvm::object;
23 static unsigned char *processFDE(unsigned char *P, intptr_t DeltaForText,
24 intptr_t DeltaForEH) {
25 uint32_t Length = *((uint32_t *)P);
27 unsigned char *Ret = P + Length;
28 uint32_t Offset = *((uint32_t *)P);
29 if (Offset == 0) // is a CIE
33 intptr_t FDELocation = *((intptr_t *)P);
34 intptr_t NewLocation = FDELocation - DeltaForText;
35 *((intptr_t *)P) = NewLocation;
36 P += sizeof(intptr_t);
38 // Skip the FDE address range
39 P += sizeof(intptr_t);
41 uint8_t Augmentationsize = *P;
43 if (Augmentationsize != 0) {
44 intptr_t LSDA = *((intptr_t *)P);
45 intptr_t NewLSDA = LSDA - DeltaForEH;
46 *((intptr_t *)P) = NewLSDA;
52 static intptr_t computeDelta(SectionEntry *A, SectionEntry *B) {
53 intptr_t ObjDistance = A->ObjAddress - B->ObjAddress;
54 intptr_t MemDistance = A->LoadAddress - B->LoadAddress;
55 return ObjDistance - MemDistance;
58 void RuntimeDyldMachO::registerEHFrames() {
62 for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
63 EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
64 if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
65 SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
67 SectionEntry *Text = &Sections[SectionInfo.TextSID];
68 SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
69 SectionEntry *ExceptTab = NULL;
70 if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
71 ExceptTab = &Sections[SectionInfo.ExceptTabSID];
73 intptr_t DeltaForText = computeDelta(Text, EHFrame);
74 intptr_t DeltaForEH = 0;
76 DeltaForEH = computeDelta(ExceptTab, EHFrame);
78 unsigned char *P = EHFrame->Address;
79 unsigned char *End = P + EHFrame->Size;
81 P = processFDE(P, DeltaForText, DeltaForEH);
84 MemMgr->registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
87 UnregisteredEHFrameSections.clear();
90 void RuntimeDyldMachO::finalizeLoad(ObjSectionToIDMap &SectionMap) {
91 unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
92 unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
93 unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
94 ObjSectionToIDMap::iterator i, e;
95 for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
96 const SectionRef &Section = i->first;
98 Section.getName(Name);
99 if (Name == "__eh_frame")
100 EHFrameSID = i->second;
101 else if (Name == "__text")
103 else if (Name == "__gcc_except_tab")
104 ExceptTabSID = i->second;
106 UnregisteredEHFrameSections.push_back(
107 EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
110 // The target location for the relocation is described by RE.SectionID and
111 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
112 // SectionEntry has three members describing its location.
113 // SectionEntry::Address is the address at which the section has been loaded
114 // into memory in the current (host) process. SectionEntry::LoadAddress is the
115 // address that the section will have in the target process.
116 // SectionEntry::ObjAddress is the address of the bits for this section in the
117 // original emitted object image (also in the current address space).
119 // Relocations will be applied as if the section were loaded at
120 // SectionEntry::LoadAddress, but they will be applied at an address based
121 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to
122 // Target memory contents if they are required for value calculations.
124 // The Value parameter here is the load address of the symbol for the
125 // relocation to be applied. For relocations which refer to symbols in the
126 // current object Value will be the LoadAddress of the section in which
127 // the symbol resides (RE.Addend provides additional information about the
128 // symbol location). For external symbols, Value will be the address of the
129 // symbol in the target address space.
130 void RuntimeDyldMachO::resolveRelocation(const RelocationEntry &RE,
132 const SectionEntry &Section = Sections[RE.SectionID];
133 return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
134 RE.IsPCRel, RE.Size);
137 void RuntimeDyldMachO::resolveRelocation(const SectionEntry &Section,
138 uint64_t Offset, uint64_t Value,
139 uint32_t Type, int64_t Addend,
140 bool isPCRel, unsigned LogSize) {
141 uint8_t *LocalAddress = Section.Address + Offset;
142 uint64_t FinalAddress = Section.LoadAddress + Offset;
143 unsigned MachoType = Type;
144 unsigned Size = 1 << LogSize;
146 DEBUG(dbgs() << "resolveRelocation LocalAddress: "
147 << format("%p", LocalAddress)
148 << " FinalAddress: " << format("%p", FinalAddress)
149 << " Value: " << format("%p", Value) << " Addend: " << Addend
150 << " isPCRel: " << isPCRel << " MachoType: " << MachoType
151 << " Size: " << Size << "\n");
153 // This just dispatches to the proper target specific routine.
156 llvm_unreachable("Unsupported CPU type!");
158 resolveX86_64Relocation(LocalAddress, FinalAddress, (uintptr_t)Value,
159 isPCRel, MachoType, Size, Addend);
162 resolveI386Relocation(LocalAddress, FinalAddress, (uintptr_t)Value, isPCRel,
163 MachoType, Size, Addend);
165 case Triple::arm: // Fall through.
167 resolveARMRelocation(LocalAddress, FinalAddress, (uintptr_t)Value, isPCRel,
168 MachoType, Size, Addend);
173 bool RuntimeDyldMachO::resolveI386Relocation(uint8_t *LocalAddress,
174 uint64_t FinalAddress,
175 uint64_t Value, bool isPCRel,
176 unsigned Type, unsigned Size,
179 Value -= FinalAddress + 4; // see resolveX86_64Relocation
183 llvm_unreachable("Invalid relocation type!");
184 case MachO::GENERIC_RELOC_VANILLA: {
185 uint8_t *p = LocalAddress;
186 uint64_t ValueToWrite = Value + Addend;
187 for (unsigned i = 0; i < Size; ++i) {
188 *p++ = (uint8_t)(ValueToWrite & 0xff);
193 case MachO::GENERIC_RELOC_SECTDIFF:
194 case MachO::GENERIC_RELOC_LOCAL_SECTDIFF:
195 case MachO::GENERIC_RELOC_PB_LA_PTR:
196 return Error("Relocation type not implemented yet!");
200 bool RuntimeDyldMachO::resolveX86_64Relocation(uint8_t *LocalAddress,
201 uint64_t FinalAddress,
202 uint64_t Value, bool isPCRel,
203 unsigned Type, unsigned Size,
205 // If the relocation is PC-relative, the value to be encoded is the
206 // pointer difference.
208 // FIXME: It seems this value needs to be adjusted by 4 for an effective PC
209 // address. Is that expected? Only for branches, perhaps?
210 Value -= FinalAddress + 4;
214 llvm_unreachable("Invalid relocation type!");
215 case MachO::X86_64_RELOC_SIGNED_1:
216 case MachO::X86_64_RELOC_SIGNED_2:
217 case MachO::X86_64_RELOC_SIGNED_4:
218 case MachO::X86_64_RELOC_SIGNED:
219 case MachO::X86_64_RELOC_UNSIGNED:
220 case MachO::X86_64_RELOC_BRANCH: {
222 // Mask in the target value a byte at a time (we don't have an alignment
223 // guarantee for the target address, so this is safest).
224 uint8_t *p = (uint8_t *)LocalAddress;
225 for (unsigned i = 0; i < Size; ++i) {
226 *p++ = (uint8_t)Value;
231 case MachO::X86_64_RELOC_GOT_LOAD:
232 case MachO::X86_64_RELOC_GOT:
233 case MachO::X86_64_RELOC_SUBTRACTOR:
234 case MachO::X86_64_RELOC_TLV:
235 return Error("Relocation type not implemented yet!");
239 bool RuntimeDyldMachO::resolveARMRelocation(uint8_t *LocalAddress,
240 uint64_t FinalAddress,
241 uint64_t Value, bool isPCRel,
242 unsigned Type, unsigned Size,
244 // If the relocation is PC-relative, the value to be encoded is the
245 // pointer difference.
247 Value -= FinalAddress;
248 // ARM PCRel relocations have an effective-PC offset of two instructions
249 // (four bytes in Thumb mode, 8 bytes in ARM mode).
250 // FIXME: For now, assume ARM mode.
256 llvm_unreachable("Invalid relocation type!");
257 case MachO::ARM_RELOC_VANILLA: {
258 // Mask in the target value a byte at a time (we don't have an alignment
259 // guarantee for the target address, so this is safest).
260 uint8_t *p = (uint8_t *)LocalAddress;
261 for (unsigned i = 0; i < Size; ++i) {
262 *p++ = (uint8_t)Value;
267 case MachO::ARM_RELOC_BR24: {
268 // Mask the value into the target address. We know instructions are
269 // 32-bit aligned, so we can do it all at once.
270 uint32_t *p = (uint32_t *)LocalAddress;
271 // The low two bits of the value are not encoded.
273 // Mask the value to 24 bits.
275 // FIXME: If the destination is a Thumb function (and the instruction
276 // is a non-predicated BL instruction), we need to change it to a BLX
277 // instruction instead.
279 // Insert the value into the instruction.
280 *p = (*p & ~0xffffff) | Value;
283 case MachO::ARM_THUMB_RELOC_BR22:
284 case MachO::ARM_THUMB_32BIT_BRANCH:
285 case MachO::ARM_RELOC_HALF:
286 case MachO::ARM_RELOC_HALF_SECTDIFF:
287 case MachO::ARM_RELOC_PAIR:
288 case MachO::ARM_RELOC_SECTDIFF:
289 case MachO::ARM_RELOC_LOCAL_SECTDIFF:
290 case MachO::ARM_RELOC_PB_LA_PTR:
291 return Error("Relocation type not implemented yet!");
296 relocation_iterator RuntimeDyldMachO::processRelocationRef(
297 unsigned SectionID, relocation_iterator RelI, ObjectImage &Obj,
298 ObjSectionToIDMap &ObjSectionToID, const SymbolTableMap &Symbols,
300 const ObjectFile *OF = Obj.getObjectFile();
301 const MachOObjectFile *MachO = static_cast<const MachOObjectFile *>(OF);
302 MachO::any_relocation_info RE =
303 MachO->getRelocation(RelI->getRawDataRefImpl());
305 uint32_t RelType = MachO->getAnyRelocationType(RE);
307 // FIXME: Properly handle scattered relocations.
308 // For now, optimistically skip these: they can often be ignored, as
309 // the static linker will already have applied the relocation, and it
310 // only needs to be reapplied if symbols move relative to one another.
311 // Note: This will fail horribly where the relocations *do* need to be
312 // applied, but that was already the case.
313 if (MachO->isRelocationScattered(RE))
316 RelocationValueRef Value;
317 SectionEntry &Section = Sections[SectionID];
319 bool isExtern = MachO->getPlainRelocationExternal(RE);
320 bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
321 unsigned Size = MachO->getAnyRelocationLength(RE);
323 RelI->getOffset(Offset);
324 uint8_t *LocalAddress = Section.Address + Offset;
325 unsigned NumBytes = 1 << Size;
327 memcpy(&Addend, LocalAddress, NumBytes);
330 // Obtain the symbol name which is referenced in the relocation
331 symbol_iterator Symbol = RelI->getSymbol();
332 StringRef TargetName;
333 Symbol->getName(TargetName);
334 // First search for the symbol in the local symbol table
335 SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
336 if (lsi != Symbols.end()) {
337 Value.SectionID = lsi->second.first;
338 Value.Addend = lsi->second.second + Addend;
340 // Search for the symbol in the global symbol table
341 SymbolTableMap::const_iterator gsi =
342 GlobalSymbolTable.find(TargetName.data());
343 if (gsi != GlobalSymbolTable.end()) {
344 Value.SectionID = gsi->second.first;
345 Value.Addend = gsi->second.second + Addend;
347 Value.SymbolName = TargetName.data();
348 Value.Addend = Addend;
352 SectionRef Sec = MachO->getRelocationSection(RE);
355 Value.SectionID = findOrEmitSection(Obj, Sec, IsCode, ObjSectionToID);
357 Sec.getAddress(Addr);
358 Value.Addend = Addend - Addr;
360 Value.Addend += Offset + NumBytes;
363 if (Arch == Triple::x86_64 && (RelType == MachO::X86_64_RELOC_GOT ||
364 RelType == MachO::X86_64_RELOC_GOT_LOAD)) {
367 StubMap::const_iterator i = Stubs.find(Value);
369 if (i != Stubs.end()) {
370 Addr = Section.Address + i->second;
372 Stubs[Value] = Section.StubOffset;
373 uint8_t *GOTEntry = Section.Address + Section.StubOffset;
374 RelocationEntry RE(SectionID, Section.StubOffset,
375 MachO::X86_64_RELOC_UNSIGNED, 0, false, 3);
376 if (Value.SymbolName)
377 addRelocationForSymbol(RE, Value.SymbolName);
379 addRelocationForSection(RE, Value.SectionID);
380 Section.StubOffset += 8;
383 resolveRelocation(Section, Offset, (uint64_t)Addr,
384 MachO::X86_64_RELOC_UNSIGNED, Value.Addend, true, 2);
385 } else if (Arch == Triple::arm && (RelType & 0xf) == MachO::ARM_RELOC_BR24) {
386 // This is an ARM branch relocation, need to use a stub function.
388 // Look up for existing stub.
389 StubMap::const_iterator i = Stubs.find(Value);
390 if (i != Stubs.end())
391 resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
392 RelType, 0, IsPCRel, Size);
394 // Create a new stub function.
395 Stubs[Value] = Section.StubOffset;
396 uint8_t *StubTargetAddr =
397 createStubFunction(Section.Address + Section.StubOffset);
398 RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
399 MachO::GENERIC_RELOC_VANILLA, Value.Addend);
400 if (Value.SymbolName)
401 addRelocationForSymbol(RE, Value.SymbolName);
403 addRelocationForSection(RE, Value.SectionID);
404 resolveRelocation(Section, Offset,
405 (uint64_t)Section.Address + Section.StubOffset, RelType,
407 Section.StubOffset += getMaxStubSize();
410 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, IsPCRel, Size);
411 if (Value.SymbolName)
412 addRelocationForSymbol(RE, Value.SymbolName);
414 addRelocationForSection(RE, Value.SectionID);
420 RuntimeDyldMachO::isCompatibleFormat(const ObjectBuffer *InputBuffer) const {
421 if (InputBuffer->getBufferSize() < 4)
423 StringRef Magic(InputBuffer->getBufferStart(), 4);
424 if (Magic == "\xFE\xED\xFA\xCE")
426 if (Magic == "\xCE\xFA\xED\xFE")
428 if (Magic == "\xFE\xED\xFA\xCF")
430 if (Magic == "\xCF\xFA\xED\xFE")
435 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile *Obj) const {
436 return Obj->isMachO();
439 } // end namespace llvm