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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 
34 public:
37  : RuntimeDyldCOFF(MM, Resolver) {}
38 
39  unsigned getMaxStubSize() override {
40  return 6; // 2-byte jmp instruction + 32-bit relative address
41  }
42 
43  // The target location for the relocation is described by RE.SectionID and
44  // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
45  // SectionEntry has three members describing its location.
46  // SectionEntry::Address is the address at which the section has been loaded
47  // into memory in the current (host) process. SectionEntry::LoadAddress is
48  // the address that the section will have in the target process.
49  // SectionEntry::ObjAddress is the address of the bits for this section in the
50  // original emitted object image (also in the current address space).
51  //
52  // Relocations will be applied as if the section were loaded at
53  // SectionEntry::LoadAddress, but they will be applied at an address based
54  // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer
55  // to Target memory contents if they are required for value calculations.
56  //
57  // The Value parameter here is the load address of the symbol for the
58  // relocation to be applied. For relocations which refer to symbols in the
59  // current object Value will be the LoadAddress of the section in which
60  // the symbol resides (RE.Addend provides additional information about the
61  // symbol location). For external symbols, Value will be the address of the
62  // symbol in the target address space.
63  void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
65  uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
66 
67  switch (RE.RelType) {
68 
75  uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
76  // Delta is the distance from the start of the reloc to the end of the
77  // instruction with the reloc.
78  uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32);
79  Value -= FinalAddress + Delta;
80  uint64_t Result = Value + RE.Addend;
81  assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow");
82  assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow");
83  writeBytesUnaligned(Result, Target, 4);
84  break;
85  }
86 
88  // Note ADDR32NB requires a well-established notion of
89  // image base. This address must be less than or equal
90  // to every section's load address, and all sections must be
91  // within a 32 bit offset from the base.
92  //
93  // For now we just set these to zero.
94  writeBytesUnaligned(0, Target, 4);
95  break;
96  }
97 
99  writeBytesUnaligned(Value + RE.Addend, Target, 8);
100  break;
101  }
102 
103  default:
104  llvm_unreachable("Relocation type not implemented yet!");
105  break;
106  }
107  }
108 
110  processRelocationRef(unsigned SectionID,
111  relocation_iterator RelI,
112  const ObjectFile &Obj,
113  ObjSectionToIDMap &ObjSectionToID,
114  StubMap &Stubs) override {
115  // If possible, find the symbol referred to in the relocation,
116  // and the section that contains it.
117  symbol_iterator Symbol = RelI->getSymbol();
118  if (Symbol == Obj.symbol_end())
119  report_fatal_error("Unknown symbol in relocation");
120  auto SectionOrError = Symbol->getSection();
121  if (!SectionOrError)
122  return SectionOrError.takeError();
123  section_iterator SecI = *SectionOrError;
124  // If there is no section, this must be an external reference.
125  const bool IsExtern = SecI == Obj.section_end();
126 
127  // Determine the Addend used to adjust the relocation value.
128  uint64_t RelType = RelI->getType();
129  uint64_t Offset = RelI->getOffset();
130  uint64_t Addend = 0;
131  SectionEntry &Section = Sections[SectionID];
132  uintptr_t ObjTarget = Section.getObjAddress() + Offset;
133 
134  switch (RelType) {
135 
143  uint8_t *Displacement = (uint8_t *)ObjTarget;
144  Addend = readBytesUnaligned(Displacement, 4);
145  break;
146  }
147 
149  uint8_t *Displacement = (uint8_t *)ObjTarget;
150  Addend = readBytesUnaligned(Displacement, 8);
151  break;
152  }
153 
154  default:
155  break;
156  }
157 
158  Expected<StringRef> TargetNameOrErr = Symbol->getName();
159  if (!TargetNameOrErr)
160  return TargetNameOrErr.takeError();
161  StringRef TargetName = *TargetNameOrErr;
162 
163  DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
164  << " RelType: " << RelType << " TargetName: " << TargetName
165  << " Addend " << Addend << "\n");
166 
167  if (IsExtern) {
168  RelocationEntry RE(SectionID, Offset, RelType, Addend);
169  addRelocationForSymbol(RE, TargetName);
170  } else {
171  bool IsCode = SecI->isText();
172  unsigned TargetSectionID;
173  if (auto TargetSectionIDOrErr =
174  findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID))
175  TargetSectionID = *TargetSectionIDOrErr;
176  else
177  return TargetSectionIDOrErr.takeError();
178  uint64_t TargetOffset = getSymbolOffset(*Symbol);
179  RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
180  addRelocationForSection(RE, TargetSectionID);
181  }
182 
183  return ++RelI;
184  }
185 
186  unsigned getStubAlignment() override { return 1; }
187  void registerEHFrames() override {
188  for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
189  uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
190  uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
191  size_t EHFrameSize = Sections[EHFrameSID].getSize();
192  MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
193  RegisteredEHFrameSections.push_back(EHFrameSID);
194  }
195  UnregisteredEHFrameSections.clear();
196  }
198  ObjSectionToIDMap &SectionMap) override {
199  // Look for and record the EH frame section IDs.
200  for (const auto &SectionPair : SectionMap) {
201  const SectionRef &Section = SectionPair.first;
202  StringRef Name;
203  if (auto EC = Section.getName(Name))
204  return errorCodeToError(EC);
205  // Note unwind info is split across .pdata and .xdata, so this
206  // may not be sufficiently general for all users.
207  if (Name == ".xdata") {
208  UnregisteredEHFrameSections.push_back(SectionPair.second);
209  }
210  }
211  return Error::success();
212  }
213 };
214 
215 } // end namespace llvm
216 
217 #undef DEBUG_TYPE
218 
219 #endif
RelocationEntry - used to represent relocations internally in the dynamic linker. ...
void push_back(const T &Elt)
Definition: SmallVector.h:212
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:115
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
Expected< StringRef > getName() const
Definition: ObjectFile.h:343
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:189
uint64_t getSymbolOffset(const SymbolRef &Sym)
Error takeError()
Take ownership of the stored error.
Definition: Error.h:537
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.
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:363
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:78
void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID)
void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override
A object file specific relocation resolver.
Symbol resolution.
Definition: JITSymbol.h:260
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:313
int64_t Addend
Addend - the relocation addend encoded in the instruction itself.
std::error_code getName(StringRef &Result) const
Definition: ObjectFile.h:398
uint32_t RelType
RelType - relocation type.
JITSymbolResolver & Resolver
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.
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:156
#define DEBUG(X)
Definition: Debug.h:118
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.
This is a value type class that represents a single section in the list of sections in the object fil...
Definition: ObjectFile.h:80
unsigned getMaxStubSize() override