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RuntimeDyldCOFFX86_64.h
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1 //===-- RuntimeDyldCOFFX86_64.h --- COFF/X86_64 specific code ---*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // COFF x86_x64 support for MC-JIT runtime dynamic linker.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
14 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
15 
16 #include "../RuntimeDyldCOFF.h"
17 #include "llvm/BinaryFormat/COFF.h"
18 #include "llvm/Object/COFF.h"
19 
20 #define DEBUG_TYPE "dyld"
21 
22 namespace llvm {
23 
25 
26 private:
27  // When a module is loaded we save the SectionID of the unwind
28  // sections in a table until we receive a request to register all
29  // unregisteredEH frame sections with the memory manager.
30  SmallVector<SID, 2> UnregisteredEHFrameSections;
31  SmallVector<SID, 2> RegisteredEHFrameSections;
32  uint64_t ImageBase;
33 
34  // Fake an __ImageBase pointer by returning the section with the lowest adress
35  uint64_t getImageBase() {
36  if (!ImageBase) {
38  for (const SectionEntry &Section : Sections)
39  // The Sections list may contain sections that weren't loaded for
40  // whatever reason: they may be debug sections, and ProcessAllSections
41  // is false, or they may be sections that contain 0 bytes. If the
42  // section isn't loaded, the load address will be 0, and it should not
43  // be included in the ImageBase calculation.
44  if (Section.getLoadAddress() != 0)
45  ImageBase = std::min(ImageBase, Section.getLoadAddress());
46  }
47  return ImageBase;
48  }
49 
50  void write32BitOffset(uint8_t *Target, int64_t Addend, uint64_t Delta) {
51  uint64_t Result = Addend + Delta;
52  assert(Result <= UINT32_MAX && "Relocation overflow");
53  writeBytesUnaligned(Result, Target, 4);
54  }
55 
56 public:
59  : RuntimeDyldCOFF(MM, Resolver, 8, COFF::IMAGE_REL_AMD64_ADDR64),
60  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() const 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 
132  assert(static_cast<int64_t>(RE.Addend) <= INT32_MAX && "Relocation overflow");
133  assert(static_cast<int64_t>(RE.Addend) >= INT32_MIN && "Relocation underflow");
134  writeBytesUnaligned(RE.Addend, Target, 4);
135  break;
136  }
137 
138  default:
139  llvm_unreachable("Relocation type not implemented yet!");
140  break;
141  }
142  }
143 
144  std::tuple<uint64_t, uint64_t, uint64_t>
145  generateRelocationStub(unsigned SectionID, StringRef TargetName,
146  uint64_t Offset, uint64_t RelType, uint64_t Addend,
147  StubMap &Stubs) {
148  uintptr_t StubOffset;
149  SectionEntry &Section = Sections[SectionID];
150 
151  RelocationValueRef OriginalRelValueRef;
152  OriginalRelValueRef.SectionID = SectionID;
153  OriginalRelValueRef.Offset = Offset;
154  OriginalRelValueRef.Addend = Addend;
155  OriginalRelValueRef.SymbolName = TargetName.data();
156 
157  auto Stub = Stubs.find(OriginalRelValueRef);
158  if (Stub == Stubs.end()) {
159  LLVM_DEBUG(dbgs() << " Create a new stub function for "
160  << TargetName.data() << "\n");
161 
162  StubOffset = Section.getStubOffset();
163  Stubs[OriginalRelValueRef] = StubOffset;
164  createStubFunction(Section.getAddressWithOffset(StubOffset));
166  } else {
167  LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()
168  << "\n");
169  StubOffset = Stub->second;
170  }
171 
172  // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able
173  // to ignore the __ImageBase requirement and just forward to the stub
174  // directly as an offset of this section:
175  // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset);
176  // .xdata exception handler's aren't having this though.
177 
178  // Resolve original relocation to stub function.
179  const RelocationEntry RE(SectionID, Offset, RelType, Addend);
180  resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));
181 
182  // adjust relocation info so resolution writes to the stub function
183  Addend = 0;
184  Offset = StubOffset + 6;
186 
187  return std::make_tuple(Offset, RelType, Addend);
188  }
189 
191  processRelocationRef(unsigned SectionID,
193  const object::ObjectFile &Obj,
194  ObjSectionToIDMap &ObjSectionToID,
195  StubMap &Stubs) override {
196  // If possible, find the symbol referred to in the relocation,
197  // and the section that contains it.
198  object::symbol_iterator Symbol = RelI->getSymbol();
199  if (Symbol == Obj.symbol_end())
200  report_fatal_error("Unknown symbol in relocation");
201  auto SectionOrError = Symbol->getSection();
202  if (!SectionOrError)
203  return SectionOrError.takeError();
204  object::section_iterator SecI = *SectionOrError;
205  // If there is no section, this must be an external reference.
206  bool IsExtern = SecI == Obj.section_end();
207 
208  // Determine the Addend used to adjust the relocation value.
209  uint64_t RelType = RelI->getType();
210  uint64_t Offset = RelI->getOffset();
211  uint64_t Addend = 0;
212  SectionEntry &Section = Sections[SectionID];
213  uintptr_t ObjTarget = Section.getObjAddress() + Offset;
214 
215  Expected<StringRef> TargetNameOrErr = Symbol->getName();
216  if (!TargetNameOrErr)
217  return TargetNameOrErr.takeError();
218 
219  StringRef TargetName = *TargetNameOrErr;
220  unsigned TargetSectionID = 0;
221  uint64_t TargetOffset = 0;
222 
223  if (TargetName.startswith(getImportSymbolPrefix())) {
224  assert(IsExtern && "DLLImport not marked extern?");
225  TargetSectionID = SectionID;
226  TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName);
227  TargetName = StringRef();
228  IsExtern = false;
229  } else if (!IsExtern) {
230  if (auto TargetSectionIDOrErr =
231  findOrEmitSection(Obj, *SecI, SecI->isText(), ObjSectionToID))
232  TargetSectionID = *TargetSectionIDOrErr;
233  else
234  return TargetSectionIDOrErr.takeError();
235  TargetOffset = getSymbolOffset(*Symbol);
236  }
237 
238  switch (RelType) {
239 
247  uint8_t *Displacement = (uint8_t *)ObjTarget;
248  Addend = readBytesUnaligned(Displacement, 4);
249 
250  if (IsExtern)
251  std::tie(Offset, RelType, Addend) = generateRelocationStub(
252  SectionID, TargetName, Offset, RelType, Addend, Stubs);
253 
254  break;
255  }
256 
258  uint8_t *Displacement = (uint8_t *)ObjTarget;
259  Addend = readBytesUnaligned(Displacement, 8);
260  break;
261  }
262 
263  default:
264  break;
265  }
266 
267  LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
268  << " RelType: " << RelType << " TargetName: "
269  << TargetName << " Addend " << Addend << "\n");
270 
271  if (IsExtern) {
272  RelocationEntry RE(SectionID, Offset, RelType, Addend);
273  addRelocationForSymbol(RE, TargetName);
274  } else {
275  RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
276  addRelocationForSection(RE, TargetSectionID);
277  }
278 
279  return ++RelI;
280  }
281 
282  void registerEHFrames() override {
283  for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
284  uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
285  uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
286  size_t EHFrameSize = Sections[EHFrameSID].getSize();
287  MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
288  RegisteredEHFrameSections.push_back(EHFrameSID);
289  }
290  UnregisteredEHFrameSections.clear();
291  }
292 
294  ObjSectionToIDMap &SectionMap) override {
295  // Look for and record the EH frame section IDs.
296  for (const auto &SectionPair : SectionMap) {
297  const object::SectionRef &Section = SectionPair.first;
298  Expected<StringRef> NameOrErr = Section.getName();
299  if (!NameOrErr)
300  return NameOrErr.takeError();
301 
302  // Note unwind info is stored in .pdata but often points to .xdata
303  // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager
304  // that keeps sections ordered in relation to __ImageBase is necessary.
305  if ((*NameOrErr) == ".pdata")
306  UnregisteredEHFrameSections.push_back(SectionPair.second);
307  }
308  return Error::success();
309  }
310 };
311 
312 } // end namespace llvm
313 
314 #undef DEBUG_TYPE
315 
316 #endif
RelocationEntry - used to represent relocations internally in the dynamic linker. ...
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:140
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Expected< StringRef > getName() const
Definition: ObjectFile.h:384
LLVM_NODISCARD bool startswith(StringRef Prefix) const
Check if this string starts with the given Prefix.
Definition: StringRef.h:289
void push_back(const T &Elt)
Definition: SmallVector.h:246
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:225
uint64_t getSymbolOffset(const SymbolRef &Sym)
unsigned getMaxStubSize() const override
Error takeError()
Take ownership of the stored error.
Definition: Error.h:557
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.
static constexpr StringRef getImportSymbolPrefix()
std::map< RelocationValueRef, uintptr_t > StubMap
Tagged union holding either a T or a Error.
Definition: APFloat.h:42
Expected< object::relocation_iterator > processRelocationRef(unsigned SectionID, object::relocation_iterator RelI, const object::ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) override
Parses one or more object file relocations (some object files use relocation pairs) and stores it to ...
RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM, JITSymbolResolver &Resolver)
Expected< section_iterator > getSection() const
Get section this symbol is defined in reference to.
Definition: ObjectFile.h:404
void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName)
void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID)
Interface for looking up the initializer for a variable name, used by Init::resolveReferences.
Definition: Record.h:1870
void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override
A object file specific relocation resolver.
Expected< ExpressionValue > min(const ExpressionValue &Lhs, const ExpressionValue &Rhs)
Definition: FileCheck.cpp:305
Symbol resolution interface.
Definition: JITSymbol.h:371
Error finalizeLoad(const object::ObjectFile &Obj, ObjSectionToIDMap &SectionMap) override
raw_fd_ostream & errs()
This returns a reference to a raw_ostream for standard error.
virtual basic_symbol_iterator symbol_end() const =0
uintptr_t getObjAddress() const
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.
uint64_t getDLLImportOffset(unsigned SectionID, StubMap &Stubs, StringRef Name, bool SetSectionIDMinus1=false)
static ErrorSuccess success()
Create a success value.
Definition: Error.h:332
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:350
int64_t Addend
Addend - the relocation addend encoded in the instruction itself.
uint32_t RelType
RelType - relocation type.
uint8_t * createStubFunction(uint8_t *Addr, unsigned AbiVariant=0)
Emits long jump instruction to Addr.
Expected< StringRef > getName() const
Definition: ObjectFile.h:441
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
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)
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.
LLVM_NODISCARD const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:152
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
LLVM Value Representation.
Definition: Value.h:74
Lightweight error class with error context and mandatory checking.
Definition: Error.h:157
void advanceStubOffset(unsigned StubSize)
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:57
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:122
This is a value type class that represents a single section in the list of sections in the object fil...
Definition: ObjectFile.h:80