LLVM  3.7.0
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 "llvm/Object/COFF.h"
18 #include "llvm/Support/COFF.h"
19 #include "../RuntimeDyldCOFF.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.Address + RE.Offset;
66 
67  switch (RE.RelType) {
68 
75  uint32_t *TargetAddress = (uint32_t *)Target;
76  uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
77  // Delta is the distance from the start of the reloc to the end of the
78  // instruction with the reloc.
79  uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32);
80  Value -= FinalAddress + Delta;
81  uint64_t Result = Value + RE.Addend;
82  assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow");
83  assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow");
84  *TargetAddress = Result;
85  break;
86  }
87 
89  // Note ADDR32NB requires a well-established notion of
90  // image base. This address must be less than or equal
91  // to every section's load address, and all sections must be
92  // within a 32 bit offset from the base.
93  //
94  // For now we just set these to zero.
95  uint32_t *TargetAddress = (uint32_t *)Target;
96  *TargetAddress = 0;
97  break;
98  }
99 
101  uint64_t *TargetAddress = (uint64_t *)Target;
102  *TargetAddress = Value + RE.Addend;
103  break;
104  }
105 
106  default:
107  llvm_unreachable("Relocation type not implemented yet!");
108  break;
109  }
110  }
111 
113  relocation_iterator RelI,
114  const ObjectFile &Obj,
115  ObjSectionToIDMap &ObjSectionToID,
116  StubMap &Stubs) override {
117  // If possible, find the symbol referred to in the relocation,
118  // and the section that contains it.
119  symbol_iterator Symbol = RelI->getSymbol();
120  if (Symbol == Obj.symbol_end())
121  report_fatal_error("Unknown symbol in relocation");
122  section_iterator SecI(Obj.section_end());
123  Symbol->getSection(SecI);
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.ObjAddress + Offset;
133 
134  switch (RelType) {
135 
143  uint32_t *Displacement = (uint32_t *)ObjTarget;
144  Addend = *Displacement;
145  break;
146  }
147 
149  uint64_t *Displacement = (uint64_t *)ObjTarget;
150  Addend = *Displacement;
151  break;
152  }
153 
154  default:
155  break;
156  }
157 
158  ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
159  if (std::error_code EC = TargetNameOrErr.getError())
160  report_fatal_error(EC.message());
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  findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID);
174  uint64_t TargetOffset = getSymbolOffset(*Symbol);
175  RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
176  addRelocationForSection(RE, TargetSectionID);
177  }
178 
179  return ++RelI;
180  }
181 
182  unsigned getStubAlignment() override { return 1; }
183  void registerEHFrames() override {
184  for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
185  uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
186  uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
187  size_t EHFrameSize = Sections[EHFrameSID].Size;
188  MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
189  RegisteredEHFrameSections.push_back(EHFrameSID);
190  }
191  UnregisteredEHFrameSections.clear();
192  }
193  void deregisterEHFrames() override {
194  // Stub
195  }
196  void finalizeLoad(const ObjectFile &Obj,
197  ObjSectionToIDMap &SectionMap) override {
198  // Look for and record the EH frame section IDs.
199  for (const auto &SectionPair : SectionMap) {
200  const SectionRef &Section = SectionPair.first;
201  StringRef Name;
202  Check(Section.getName(Name));
203  // Note unwind info is split across .pdata and .xdata, so this
204  // may not be sufficiently general for all users.
205  if (Name == ".xdata") {
206  UnregisteredEHFrameSections.push_back(SectionPair.second);
207  }
208  }
209  }
210 };
211 
212 } // end namespace llvm
213 
214 #undef DEBUG_TYPE
215 
216 #endif
RelocationEntry - used to represent relocations internally in the dynamic linker. ...
void push_back(const T &Elt)
Definition: SmallVector.h:222
std::error_code getError() const
Definition: ErrorOr.h:178
Represents either an error or a value T.
Definition: ErrorOr.h:82
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 ...
RuntimeDyld::MemoryManager & MemMgr
This class is the base class for all object file types.
Definition: ObjectFile.h:176
uint8_t * Address
Address - address in the linker's memory where the section resides.
unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section, bool IsCode, ObjSectionToIDMap &LocalSections)
Find Section in LocalSections.
uint64_t getSymbolOffset(const SymbolRef &Sym)
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const char *reason, bool gen_crash_diag=true)
Reports a serious error, calling any installed error handler.
unsigned getStubAlignment() override
unsigned SectionID
SectionID - the section this relocation points to.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
std::map< RelocationValueRef, uintptr_t > StubMap
std::error_code getName(StringRef &Result) const
Definition: ObjectFile.h:362
void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName)
RuntimeDyld::SymbolResolver & Resolver
void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID)
void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override
A object file specific relocation resolver.
basic_symbol_iterator symbol_end() const
Definition: SymbolicFile.h:139
RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM, RuntimeDyld::SymbolResolver &Resolver)
int64_t Addend
Addend - the relocation addend encoded in the instruction itself.
uint32_t RelType
RelType - relocation type.
void finalizeLoad(const ObjectFile &Obj, ObjSectionToIDMap &SectionMap) override
uint64_t TargetAddress
Represents an address in the target process's address space.
Definition: JITSymbol.h:26
uintptr_t ObjAddress
ObjAddress - address of the section in the in-memory object file.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
Target - Wrapper for Target specific information.
ErrorOr< StringRef > getName() const
Definition: ObjectFile.h:306
uint64_t Offset
Offset - offset into the section.
virtual section_iterator section_end() const =0
std::map< SectionRef, unsigned > ObjSectionToIDMap
std::error_code Check(std::error_code Err)
uint64_t LoadAddress
LoadAddress - the address of the section in the target process's memory.
SectionEntry - represents a section emitted into memory by the dynamic linker.
LLVM Value Representation.
Definition: Value.h:69
#define DEBUG(X)
Definition: Debug.h:92
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
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.
std::error_code getSection(section_iterator &Result) const
Get section this symbol is defined in reference to.
Definition: ObjectFile.h:326
This is a value type class that represents a single section in the list of sections in the object fil...
Definition: ObjectFile.h:69
unsigned getMaxStubSize() override