LLVM  3.7.0
RuntimeDyldImpl.h
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1 //===-- RuntimeDyldImpl.h - Run-time dynamic linker for MC-JIT --*- 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 // Interface for the implementations of runtime dynamic linker facilities.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDIMPL_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDIMPL_H
16 
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/Triple.h"
24 #include "llvm/Object/ObjectFile.h"
25 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/Format.h"
28 #include "llvm/Support/Host.h"
29 #include "llvm/Support/Mutex.h"
32 #include <map>
33 #include <system_error>
34 
35 using namespace llvm;
36 using namespace llvm::object;
37 
38 namespace llvm {
39 
40  // Helper for extensive error checking in debug builds.
41 inline std::error_code Check(std::error_code Err) {
42  if (Err) {
43  report_fatal_error(Err.message());
44  }
45  return Err;
46 }
47 
48 class Twine;
49 
50 /// SectionEntry - represents a section emitted into memory by the dynamic
51 /// linker.
52 class SectionEntry {
53 public:
54  /// Name - section name.
55  std::string Name;
56 
57  /// Address - address in the linker's memory where the section resides.
58  uint8_t *Address;
59 
60  /// Size - section size. Doesn't include the stubs.
61  size_t Size;
62 
63  /// LoadAddress - the address of the section in the target process's memory.
64  /// Used for situations in which JIT-ed code is being executed in the address
65  /// space of a separate process. If the code executes in the same address
66  /// space where it was JIT-ed, this just equals Address.
67  uint64_t LoadAddress;
68 
69  /// StubOffset - used for architectures with stub functions for far
70  /// relocations (like ARM).
71  uintptr_t StubOffset;
72 
73  /// ObjAddress - address of the section in the in-memory object file. Used
74  /// for calculating relocations in some object formats (like MachO).
75  uintptr_t ObjAddress;
76 
77  SectionEntry(StringRef name, uint8_t *address, size_t size,
78  uintptr_t objAddress)
79  : Name(name), Address(address), Size(size),
80  LoadAddress(reinterpret_cast<uintptr_t>(address)), StubOffset(size),
81  ObjAddress(objAddress) {}
82 };
83 
84 /// RelocationEntry - used to represent relocations internally in the dynamic
85 /// linker.
87 public:
88  /// SectionID - the section this relocation points to.
89  unsigned SectionID;
90 
91  /// Offset - offset into the section.
92  uint64_t Offset;
93 
94  /// RelType - relocation type.
95  uint32_t RelType;
96 
97  /// Addend - the relocation addend encoded in the instruction itself. Also
98  /// used to make a relocation section relative instead of symbol relative.
99  int64_t Addend;
100 
101  struct SectionPair {
102  uint32_t SectionA;
103  uint32_t SectionB;
104  };
105 
106  /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
107  /// lookup).
108  union {
109  uint64_t SymOffset;
111  };
112 
113  /// True if this is a PCRel relocation (MachO specific).
114  bool IsPCRel;
115 
116  /// The size of this relocation (MachO specific).
117  unsigned Size;
118 
119  RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
120  : SectionID(id), Offset(offset), RelType(type), Addend(addend),
121  SymOffset(0), IsPCRel(false), Size(0) {}
122 
123  RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
124  uint64_t symoffset)
125  : SectionID(id), Offset(offset), RelType(type), Addend(addend),
126  SymOffset(symoffset), IsPCRel(false), Size(0) {}
127 
128  RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
129  bool IsPCRel, unsigned Size)
130  : SectionID(id), Offset(offset), RelType(type), Addend(addend),
131  SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
132 
133  RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
134  unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
135  uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
136  : SectionID(id), Offset(offset), RelType(type),
137  Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
138  Size(Size) {
139  Sections.SectionA = SectionA;
140  Sections.SectionB = SectionB;
141  }
142 };
143 
145 public:
146  unsigned SectionID;
147  uint64_t Offset;
148  int64_t Addend;
149  const char *SymbolName;
150  RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
151  SymbolName(nullptr) {}
152 
153  inline bool operator==(const RelocationValueRef &Other) const {
154  return SectionID == Other.SectionID && Offset == Other.Offset &&
155  Addend == Other.Addend && SymbolName == Other.SymbolName;
156  }
157  inline bool operator<(const RelocationValueRef &Other) const {
158  if (SectionID != Other.SectionID)
159  return SectionID < Other.SectionID;
160  if (Offset != Other.Offset)
161  return Offset < Other.Offset;
162  if (Addend != Other.Addend)
163  return Addend < Other.Addend;
164  return SymbolName < Other.SymbolName;
165  }
166 };
167 
168 /// @brief Symbol info for RuntimeDyld.
170 public:
172  : JITSymbolBase(JITSymbolFlags::None), Offset(0), SectionID(0) {}
173 
174  SymbolTableEntry(unsigned SectionID, uint64_t Offset, JITSymbolFlags Flags)
175  : JITSymbolBase(Flags), Offset(Offset), SectionID(SectionID) {}
176 
177  unsigned getSectionID() const { return SectionID; }
178  uint64_t getOffset() const { return Offset; }
179 
180 private:
181  uint64_t Offset;
182  unsigned SectionID;
183 };
184 
186 
190 protected:
191  // The MemoryManager to load objects into.
193 
194  // The symbol resolver to use for external symbols.
196 
197  // Attached RuntimeDyldChecker instance. Null if no instance attached.
199 
200  // A list of all sections emitted by the dynamic linker. These sections are
201  // referenced in the code by means of their index in this list - SectionID.
204 
205  typedef unsigned SID; // Type for SectionIDs
206 #define RTDYLD_INVALID_SECTION_ID ((RuntimeDyldImpl::SID)(-1))
207 
208  // Keep a map of sections from object file to the SectionID which
209  // references it.
210  typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
211 
212  // A global symbol table for symbols from all loaded modules.
214 
215  // Keep a map of common symbols to their info pairs
216  typedef std::vector<SymbolRef> CommonSymbolList;
217 
218  // For each symbol, keep a list of relocations based on it. Anytime
219  // its address is reassigned (the JIT re-compiled the function, e.g.),
220  // the relocations get re-resolved.
221  // The symbol (or section) the relocation is sourced from is the Key
222  // in the relocation list where it's stored.
224  // Relocations to sections already loaded. Indexed by SectionID which is the
225  // source of the address. The target where the address will be written is
226  // SectionID/Offset in the relocation itself.
228 
229  // Relocations to external symbols that are not yet resolved. Symbols are
230  // external when they aren't found in the global symbol table of all loaded
231  // modules. This map is indexed by symbol name.
233 
234 
235  typedef std::map<RelocationValueRef, uintptr_t> StubMap;
236 
241 
242  // True if all sections should be passed to the memory manager, false if only
243  // sections containing relocations should be. Defaults to 'false'.
245 
246  // This mutex prevents simultaneously loading objects from two different
247  // threads. This keeps us from having to protect individual data structures
248  // and guarantees that section allocation requests to the memory manager
249  // won't be interleaved between modules. It is also used in mapSectionAddress
250  // and resolveRelocations to protect write access to internal data structures.
251  //
252  // loadObject may be called on the same thread during the handling of of
253  // processRelocations, and that's OK. The handling of the relocation lists
254  // is written in such a way as to work correctly if new elements are added to
255  // the end of the list while the list is being processed.
257 
258  virtual unsigned getMaxStubSize() = 0;
259  virtual unsigned getStubAlignment() = 0;
260 
261  bool HasError;
262  std::string ErrorStr;
263 
264  // Set the error state and record an error string.
265  bool Error(const Twine &Msg) {
266  ErrorStr = Msg.str();
267  HasError = true;
268  return true;
269  }
270 
271  uint64_t getSectionLoadAddress(unsigned SectionID) const {
272  return Sections[SectionID].LoadAddress;
273  }
274 
275  uint8_t *getSectionAddress(unsigned SectionID) const {
276  return (uint8_t *)Sections[SectionID].Address;
277  }
278 
279  void writeInt16BE(uint8_t *Addr, uint16_t Value) {
280  if (IsTargetLittleEndian)
281  sys::swapByteOrder(Value);
282  *Addr = (Value >> 8) & 0xFF;
283  *(Addr + 1) = Value & 0xFF;
284  }
285 
286  void writeInt32BE(uint8_t *Addr, uint32_t Value) {
287  if (IsTargetLittleEndian)
288  sys::swapByteOrder(Value);
289  *Addr = (Value >> 24) & 0xFF;
290  *(Addr + 1) = (Value >> 16) & 0xFF;
291  *(Addr + 2) = (Value >> 8) & 0xFF;
292  *(Addr + 3) = Value & 0xFF;
293  }
294 
295  void writeInt64BE(uint8_t *Addr, uint64_t Value) {
296  if (IsTargetLittleEndian)
297  sys::swapByteOrder(Value);
298  *Addr = (Value >> 56) & 0xFF;
299  *(Addr + 1) = (Value >> 48) & 0xFF;
300  *(Addr + 2) = (Value >> 40) & 0xFF;
301  *(Addr + 3) = (Value >> 32) & 0xFF;
302  *(Addr + 4) = (Value >> 24) & 0xFF;
303  *(Addr + 5) = (Value >> 16) & 0xFF;
304  *(Addr + 6) = (Value >> 8) & 0xFF;
305  *(Addr + 7) = Value & 0xFF;
306  }
307 
308  virtual void setMipsABI(const ObjectFile &Obj) {
309  IsMipsO32ABI = false;
310  IsMipsN64ABI = false;
311  }
312 
313  /// Endian-aware read Read the least significant Size bytes from Src.
314  uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const;
315 
316  /// Endian-aware write. Write the least significant Size bytes from Value to
317  /// Dst.
318  void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const;
319 
320  /// \brief Given the common symbols discovered in the object file, emit a
321  /// new section for them and update the symbol mappings in the object and
322  /// symbol table.
323  void emitCommonSymbols(const ObjectFile &Obj, CommonSymbolList &CommonSymbols);
324 
325  /// \brief Emits section data from the object file to the MemoryManager.
326  /// \param IsCode if it's true then allocateCodeSection() will be
327  /// used for emits, else allocateDataSection() will be used.
328  /// \return SectionID.
329  unsigned emitSection(const ObjectFile &Obj, const SectionRef &Section,
330  bool IsCode);
331 
332  /// \brief Find Section in LocalSections. If the secton is not found - emit
333  /// it and store in LocalSections.
334  /// \param IsCode if it's true then allocateCodeSection() will be
335  /// used for emmits, else allocateDataSection() will be used.
336  /// \return SectionID.
337  unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section,
338  bool IsCode, ObjSectionToIDMap &LocalSections);
339 
340  // \brief Add a relocation entry that uses the given section.
341  void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
342 
343  // \brief Add a relocation entry that uses the given symbol. This symbol may
344  // be found in the global symbol table, or it may be external.
345  void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
346 
347  /// \brief Emits long jump instruction to Addr.
348  /// \return Pointer to the memory area for emitting target address.
349  uint8_t *createStubFunction(uint8_t *Addr, unsigned AbiVariant = 0);
350 
351  /// \brief Resolves relocations from Relocs list with address from Value.
352  void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
353 
354  /// \brief A object file specific relocation resolver
355  /// \param RE The relocation to be resolved
356  /// \param Value Target symbol address to apply the relocation action
357  virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
358 
359  /// \brief Parses one or more object file relocations (some object files use
360  /// relocation pairs) and stores it to Relocations or SymbolRelocations
361  /// (this depends on the object file type).
362  /// \return Iterator to the next relocation that needs to be parsed.
363  virtual relocation_iterator
364  processRelocationRef(unsigned SectionID, relocation_iterator RelI,
365  const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
366  StubMap &Stubs) = 0;
367 
368  /// \brief Resolve relocations to external symbols.
369  void resolveExternalSymbols();
370 
371  // \brief Compute an upper bound of the memory that is required to load all
372  // sections
373  void computeTotalAllocSize(const ObjectFile &Obj, uint64_t &CodeSize,
374  uint64_t &DataSizeRO, uint64_t &DataSizeRW);
375 
376  // \brief Compute the stub buffer size required for a section
377  unsigned computeSectionStubBufSize(const ObjectFile &Obj,
378  const SectionRef &Section);
379 
380  // \brief Implementation of the generic part of the loadObject algorithm.
381  std::pair<unsigned, unsigned> loadObjectImpl(const object::ObjectFile &Obj);
382 
383 public:
385  RuntimeDyld::SymbolResolver &Resolver)
386  : MemMgr(MemMgr), Resolver(Resolver), Checker(nullptr),
387  ProcessAllSections(false), HasError(false) {
388  }
389 
390  virtual ~RuntimeDyldImpl();
391 
392  void setProcessAllSections(bool ProcessAllSections) {
393  this->ProcessAllSections = ProcessAllSections;
394  }
395 
397  this->Checker = Checker;
398  }
399 
400  virtual std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
401  loadObject(const object::ObjectFile &Obj) = 0;
402 
404  // FIXME: Just look up as a function for now. Overly simple of course.
405  // Work in progress.
406  RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
407  if (pos == GlobalSymbolTable.end())
408  return nullptr;
409  const auto &SymInfo = pos->second;
410  return getSectionAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
411  }
412 
414  // FIXME: Just look up as a function for now. Overly simple of course.
415  // Work in progress.
416  RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
417  if (pos == GlobalSymbolTable.end())
418  return nullptr;
419  const auto &SymEntry = pos->second;
420  uint64_t TargetAddr =
421  getSectionLoadAddress(SymEntry.getSectionID()) + SymEntry.getOffset();
422  return RuntimeDyld::SymbolInfo(TargetAddr, SymEntry.getFlags());
423  }
424 
425  void resolveRelocations();
426 
427  void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
428 
429  void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
430 
431  // Is the linker in an error state?
432  bool hasError() { return HasError; }
433 
434  // Mark the error condition as handled and continue.
435  void clearError() { HasError = false; }
436 
437  // Get the error message.
438  StringRef getErrorString() { return ErrorStr; }
439 
440  virtual bool isCompatibleFile(const ObjectFile &Obj) const = 0;
441 
442  virtual void registerEHFrames();
443 
444  virtual void deregisterEHFrames();
445 
446  virtual void finalizeLoad(const ObjectFile &ObjImg,
447  ObjSectionToIDMap &SectionMap) {}
448 };
449 
450 } // end namespace llvm
451 
452 #endif
const NoneType None
Definition: None.h:23
Information about the loaded object.
Definition: RuntimeDyld.h:59
RelocationEntry - used to represent relocations internally in the dynamic linker. ...
size_t Size
Size - section size. Doesn't include the stubs.
RuntimeDyldImpl(RuntimeDyld::MemoryManager &MemMgr, RuntimeDyld::SymbolResolver &Resolver)
void swapByteOrder(T &Value)
virtual void setMipsABI(const ObjectFile &Obj)
void writeInt16BE(uint8_t *Addr, uint16_t Value)
std::string Name
Name - section name.
RuntimeDyld::MemoryManager & MemMgr
This class is the base class for all object file types.
Definition: ObjectFile.h:176
RuntimeDyldCheckerImpl * Checker
uint8_t * Address
Address - address in the linker's memory where the section resides.
RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend, uint64_t symoffset)
Base class for symbols in the JIT.
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const char *reason, bool gen_crash_diag=true)
Reports a serious error, calling any installed error handler.
bool IsPCRel
True if this is a PCRel relocation (MachO specific).
unsigned SectionID
SectionID - the section this relocation points to.
std::string str() const
Return the twine contents as a std::string.
Definition: Twine.cpp:16
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:79
bool operator<(const RelocationValueRef &Other) const
std::map< RelocationValueRef, uintptr_t > StubMap
uintptr_t StubOffset
StubOffset - used for architectures with stub functions for far relocations (like ARM)...
#define false
Definition: ConvertUTF.c:65
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:591
virtual void finalizeLoad(const ObjectFile &ObjImg, ObjSectionToIDMap &SectionMap)
RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
bool Error(const Twine &Msg)
JITSymbolFlags
Flags for symbols in the JIT.
RuntimeDyld::SymbolResolver & Resolver
DenseMap< unsigned, RelocationList > Relocations
void setRuntimeDyldChecker(RuntimeDyldCheckerImpl *Checker)
SmallVector< SectionEntry, 64 > SectionList
uint8_t * getSectionAddress(unsigned SectionID) const
std::vector< SymbolRef > CommonSymbolList
void writeInt32BE(uint8_t *Addr, uint32_t Value)
StringMap< SymbolTableEntry > RTDyldSymbolTable
int64_t Addend
Addend - the relocation addend encoded in the instruction itself.
uint32_t RelType
RelType - relocation type.
RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend, bool IsPCRel, unsigned Size)
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.
Symbol info for RuntimeDyld.
void setProcessAllSections(bool ProcessAllSections)
SectionEntry(StringRef name, uint8_t *address, size_t size, uintptr_t objAddress)
RuntimeDyld::SymbolInfo getSymbol(StringRef Name) const
Triple::ArchType Arch
uint64_t Offset
Offset - offset into the section.
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.
void writeInt64BE(uint8_t *Addr, uint64_t Value)
Information about a named symbol.
Definition: RuntimeDyld.h:47
void size_t size
uint64_t getOffset() const
RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend, unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB, uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
SectionEntry - represents a section emitted into memory by the dynamic linker.
SymbolTableEntry(unsigned SectionID, uint64_t Offset, JITSymbolFlags Flags)
LLVM Value Representation.
Definition: Value.h:69
static const char * name
RTDyldSymbolTable GlobalSymbolTable
unsigned Size
The size of this relocation (MachO specific).
uint8_t * getSymbolLocalAddress(StringRef Name) const
unsigned getSectionID() const
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
uint64_t getSectionLoadAddress(unsigned SectionID) const
bool operator==(const RelocationValueRef &Other) const
StringMap< RelocationList > ExternalSymbolRelocations
SmallVector< RelocationEntry, 64 > RelocationList
This is a value type class that represents a single section in the list of sections in the object fil...
Definition: ObjectFile.h:69