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RuntimeDyldCOFFX86_64.h
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1 //===-- RuntimeDyldCOFFX86_64.h --- COFF/X86_64 specific code ---*- 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 // COFF x86_x64 support for MC-JIT runtime dynamic linker.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
16 
17 #include "../RuntimeDyldCOFF.h"
18 #include "llvm/BinaryFormat/COFF.h"
19 #include "llvm/Object/COFF.h"
20 
21 #define DEBUG_TYPE "dyld"
22 
23 namespace llvm {
24 
26 
27 private:
28  // When a module is loaded we save the SectionID of the unwind
29  // sections in a table until we receive a request to register all
30  // unregisteredEH frame sections with the memory manager.
31  SmallVector<SID, 2> UnregisteredEHFrameSections;
32  SmallVector<SID, 2> RegisteredEHFrameSections;
33  uint64_t ImageBase;
34 
35  // Fake an __ImageBase pointer by returning the section with the lowest adress
36  uint64_t getImageBase() {
37  if (!ImageBase) {
39  for (const SectionEntry &Section : Sections)
40  // The Sections list may contain sections that weren't loaded for
41  // whatever reason: they may be debug sections, and ProcessAllSections
42  // is false, or they may be sections that contain 0 bytes. If the
43  // section isn't loaded, the load address will be 0, and it should not
44  // be included in the ImageBase calculation.
45  if (Section.getLoadAddress() != 0)
46  ImageBase = std::min(ImageBase, Section.getLoadAddress());
47  }
48  return ImageBase;
49  }
50 
51  void write32BitOffset(uint8_t *Target, int64_t Addend, uint64_t Delta) {
52  uint64_t Result = Addend + Delta;
53  assert(Result <= UINT32_MAX && "Relocation overflow");
54  writeBytesUnaligned(Result, Target, 4);
55  }
56 
57 public:
60  : RuntimeDyldCOFF(MM, Resolver), ImageBase(0) {}
61 
62  unsigned getStubAlignment() override { return 1; }
63 
64  // 2-byte jmp instruction + 32-bit relative address + 64-bit absolute jump
65  unsigned getMaxStubSize() override { return 14; }
66 
67  // The target location for the relocation is described by RE.SectionID and
68  // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
69  // SectionEntry has three members describing its location.
70  // SectionEntry::Address is the address at which the section has been loaded
71  // into memory in the current (host) process. SectionEntry::LoadAddress is
72  // the address that the section will have in the target process.
73  // SectionEntry::ObjAddress is the address of the bits for this section in the
74  // original emitted object image (also in the current address space).
75  //
76  // Relocations will be applied as if the section were loaded at
77  // SectionEntry::LoadAddress, but they will be applied at an address based
78  // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer
79  // to Target memory contents if they are required for value calculations.
80  //
81  // The Value parameter here is the load address of the symbol for the
82  // relocation to be applied. For relocations which refer to symbols in the
83  // current object Value will be the LoadAddress of the section in which
84  // the symbol resides (RE.Addend provides additional information about the
85  // symbol location). For external symbols, Value will be the address of the
86  // symbol in the target address space.
87  void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
89  uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
90 
91  switch (RE.RelType) {
92 
99  uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
100  // Delta is the distance from the start of the reloc to the end of the
101  // instruction with the reloc.
102  uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32);
103  Value -= FinalAddress + Delta;
104  uint64_t Result = Value + RE.Addend;
105  assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow");
106  assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow");
107  writeBytesUnaligned(Result, Target, 4);
108  break;
109  }
110 
112  // ADDR32NB requires an offset less than 2GB from 'ImageBase'.
113  // The MemoryManager can make sure this is always true by forcing the
114  // memory layout to be: CodeSection < ReadOnlySection < ReadWriteSection.
115  const uint64_t ImageBase = getImageBase();
116  if (Value < ImageBase || ((Value - ImageBase) > UINT32_MAX)) {
117  llvm::errs() << "IMAGE_REL_AMD64_ADDR32NB relocation requires an"
118  << "ordered section layout.\n";
119  write32BitOffset(Target, 0, 0);
120  } else {
121  write32BitOffset(Target, RE.Addend, Value - ImageBase);
122  }
123  break;
124  }
125 
127  writeBytesUnaligned(Value + RE.Addend, Target, 8);
128  break;
129  }
130 
131  default:
132  llvm_unreachable("Relocation type not implemented yet!");
133  break;
134  }
135  }
136 
137  std::tuple<uint64_t, uint64_t, uint64_t>
138  generateRelocationStub(unsigned SectionID, StringRef TargetName,
139  uint64_t Offset, uint64_t RelType, uint64_t Addend,
140  StubMap &Stubs) {
141  uintptr_t StubOffset;
142  SectionEntry &Section = Sections[SectionID];
143 
144  RelocationValueRef OriginalRelValueRef;
145  OriginalRelValueRef.SectionID = SectionID;
146  OriginalRelValueRef.Offset = Offset;
147  OriginalRelValueRef.Addend = Addend;
148  OriginalRelValueRef.SymbolName = TargetName.data();
149 
150  auto Stub = Stubs.find(OriginalRelValueRef);
151  if (Stub == Stubs.end()) {
152  LLVM_DEBUG(dbgs() << " Create a new stub function for "
153  << TargetName.data() << "\n");
154 
155  StubOffset = Section.getStubOffset();
156  Stubs[OriginalRelValueRef] = StubOffset;
157  createStubFunction(Section.getAddressWithOffset(StubOffset));
159  } else {
160  LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()
161  << "\n");
162  StubOffset = Stub->second;
163  }
164 
165  // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able
166  // to ignore the __ImageBase requirement and just forward to the stub
167  // directly as an offset of this section:
168  // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset);
169  // .xdata exception handler's aren't having this though.
170 
171  // Resolve original relocation to stub function.
172  const RelocationEntry RE(SectionID, Offset, RelType, Addend);
173  resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));
174 
175  // adjust relocation info so resolution writes to the stub function
176  Addend = 0;
177  Offset = StubOffset + 6;
179 
180  return std::make_tuple(Offset, RelType, Addend);
181  }
182 
184  processRelocationRef(unsigned SectionID,
185  relocation_iterator RelI,
186  const ObjectFile &Obj,
187  ObjSectionToIDMap &ObjSectionToID,
188  StubMap &Stubs) override {
189  // If possible, find the symbol referred to in the relocation,
190  // and the section that contains it.
191  symbol_iterator Symbol = RelI->getSymbol();
192  if (Symbol == Obj.symbol_end())
193  report_fatal_error("Unknown symbol in relocation");
194  auto SectionOrError = Symbol->getSection();
195  if (!SectionOrError)
196  return SectionOrError.takeError();
197  section_iterator SecI = *SectionOrError;
198  // If there is no section, this must be an external reference.
199  const bool IsExtern = SecI == Obj.section_end();
200 
201  // Determine the Addend used to adjust the relocation value.
202  uint64_t RelType = RelI->getType();
203  uint64_t Offset = RelI->getOffset();
204  uint64_t Addend = 0;
205  SectionEntry &Section = Sections[SectionID];
206  uintptr_t ObjTarget = Section.getObjAddress() + Offset;
207 
208  Expected<StringRef> TargetNameOrErr = Symbol->getName();
209  if (!TargetNameOrErr)
210  return TargetNameOrErr.takeError();
211  StringRef TargetName = *TargetNameOrErr;
212 
213  switch (RelType) {
214 
222  uint8_t *Displacement = (uint8_t *)ObjTarget;
223  Addend = readBytesUnaligned(Displacement, 4);
224 
225  if (IsExtern)
226  std::tie(Offset, RelType, Addend) = generateRelocationStub(
227  SectionID, TargetName, Offset, RelType, Addend, Stubs);
228 
229  break;
230  }
231 
233  uint8_t *Displacement = (uint8_t *)ObjTarget;
234  Addend = readBytesUnaligned(Displacement, 8);
235  break;
236  }
237 
238  default:
239  break;
240  }
241 
242  LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
243  << " RelType: " << RelType << " TargetName: "
244  << TargetName << " Addend " << Addend << "\n");
245 
246  if (IsExtern) {
247  RelocationEntry RE(SectionID, Offset, RelType, Addend);
248  addRelocationForSymbol(RE, TargetName);
249  } else {
250  bool IsCode = SecI->isText();
251  unsigned TargetSectionID;
252  if (auto TargetSectionIDOrErr =
253  findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID))
254  TargetSectionID = *TargetSectionIDOrErr;
255  else
256  return TargetSectionIDOrErr.takeError();
257  uint64_t TargetOffset = getSymbolOffset(*Symbol);
258  RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
259  addRelocationForSection(RE, TargetSectionID);
260  }
261 
262  return ++RelI;
263  }
264 
265  void registerEHFrames() override {
266  for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
267  uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
268  uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
269  size_t EHFrameSize = Sections[EHFrameSID].getSize();
270  MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
271  RegisteredEHFrameSections.push_back(EHFrameSID);
272  }
273  UnregisteredEHFrameSections.clear();
274  }
275 
277  ObjSectionToIDMap &SectionMap) override {
278  // Look for and record the EH frame section IDs.
279  for (const auto &SectionPair : SectionMap) {
280  const SectionRef &Section = SectionPair.first;
281  StringRef Name;
282  if (auto EC = Section.getName(Name))
283  return errorCodeToError(EC);
284 
285  // Note unwind info is stored in .pdata but often points to .xdata
286  // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager
287  // that keeps sections ordered in relation to __ImageBase is necessary.
288  if (Name == ".pdata")
289  UnregisteredEHFrameSections.push_back(SectionPair.second);
290  }
291  return Error::success();
292  }
293 };
294 
295 } // end namespace llvm
296 
297 #undef DEBUG_TYPE
298 
299 #endif
RelocationEntry - used to represent relocations internally in the dynamic linker. ...
void push_back(const T &Elt)
Definition: SmallVector.h:218
raw_ostream & errs()
This returns a reference to a raw_ostream for standard error.
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:139
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
Expected< StringRef > getName() const
Definition: ObjectFile.h:345
uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const
Endian-aware read Read the least significant Size bytes from Src.
uint64_t getLoadAddressWithOffset(unsigned OffsetBytes) const
Return the load address of this section with an offset.
RuntimeDyld::MemoryManager & MemMgr
This class is the base class for all object file types.
Definition: ObjectFile.h:190
uint64_t getSymbolOffset(const SymbolRef &Sym)
Error takeError()
Take ownership of the stored error.
Definition: Error.h:553
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:128
void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const
Endian-aware write.
unsigned getStubAlignment() override
unsigned SectionID
SectionID - the section this relocation points to.
amdgpu Simplify well known AMD library false Value Value const Twine & Name
std::map< RelocationValueRef, uintptr_t > StubMap
Tagged union holding either a T or a Error.
Definition: CachePruning.h:23
RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM, JITSymbolResolver &Resolver)
Expected< section_iterator > getSection() const
Get section this symbol is defined in reference to.
Definition: ObjectFile.h:365
void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName)
Error errorCodeToError(std::error_code EC)
Helper for converting an std::error_code to a Error.
Definition: Error.cpp:87
void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID)
Interface for looking up the initializer for a variable name, used by Init::resolveReferences.
Definition: Record.h:1774
void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override
A object file specific relocation resolver.
Symbol resolution interface.
Definition: JITSymbol.h:332
virtual basic_symbol_iterator symbol_end() const =0
uintptr_t getObjAddress() const
Error finalizeLoad(const ObjectFile &Obj, ObjSectionToIDMap &SectionMap) override
Expected< unsigned > findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section, bool IsCode, ObjSectionToIDMap &LocalSections)
Find Section in LocalSections.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
static ErrorSuccess success()
Create a success value.
Definition: Error.h:327
int64_t Addend
Addend - the relocation addend encoded in the instruction itself.
std::error_code getName(StringRef &Result) const
Definition: ObjectFile.h:400
uint32_t RelType
RelType - relocation type.
uint8_t * createStubFunction(uint8_t *Addr, unsigned AbiVariant=0)
Emits long jump instruction to Addr.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
Target - Wrapper for Target specific information.
uintptr_t getStubOffset() const
std::tuple< uint64_t, uint64_t, uint64_t > generateRelocationStub(unsigned SectionID, StringRef TargetName, uint64_t Offset, uint64_t RelType, uint64_t Addend, StubMap &Stubs)
Expected< relocation_iterator > processRelocationRef(unsigned SectionID, relocation_iterator RelI, const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) override
Parses one or more object file relocations (some object files use relocation pairs) and stores it to ...
uint64_t Offset
Offset - offset into the section.
virtual section_iterator section_end() const =0
std::map< SectionRef, unsigned > ObjSectionToIDMap
uint8_t * getAddressWithOffset(unsigned OffsetBytes) const
Return the address of this section with an offset.
SectionEntry - represents a section emitted into memory by the dynamic linker.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
LLVM Value Representation.
Definition: Value.h:73
Lightweight error class with error context and mandatory checking.
Definition: Error.h:158
void advanceStubOffset(unsigned StubSize)
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, size_t Size)=0
Register the EH frames with the runtime so that c++ exceptions work.
#define LLVM_DEBUG(X)
Definition: Debug.h:123
This is a value type class that represents a single section in the list of sections in the object fil...
Definition: ObjectFile.h:81
unsigned getMaxStubSize() override