RuntimeDyldImpl.h revision 234353 
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_RUNTIME_DYLD_IMPL_H
15#define LLVM_RUNTIME_DYLD_IMPL_H
16
17#include "llvm/ExecutionEngine/RuntimeDyld.h"
18#include "llvm/Object/ObjectFile.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/ADT/StringMap.h"
21#include "llvm/ADT/Twine.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/Support/Memory.h"
24#include "llvm/Support/MemoryBuffer.h"
25#include "llvm/Support/system_error.h"
26#include "llvm/Support/raw_ostream.h"
27#include "llvm/Support/Debug.h"
28#include "llvm/Support/ErrorHandling.h"
29#include "llvm/ADT/Triple.h"
30#include <map>
31#include "llvm/Support/Format.h"
32
33using namespace llvm;
34using namespace llvm::object;
35
36namespace llvm {
37
38class SectionEntry {
39public:
40  uint8_t* Address;
41  size_t Size;
42  uint64_t LoadAddress;   // For each section, the address it will be
43                          // considered to live at for relocations. The same
44                          // as the pointer to the above memory block for
45                          // hosted JITs.
46  uintptr_t StubOffset;   // It's used for architecturies with stub
47                          // functions for far relocations like ARM.
48  uintptr_t ObjAddress;   // Section address in object file. It's use for
49                          // calculate MachO relocation addend
50  SectionEntry(uint8_t* address, size_t size, uintptr_t stubOffset,
51               uintptr_t objAddress)
52    : Address(address), Size(size), LoadAddress((uintptr_t)address),
53      StubOffset(stubOffset), ObjAddress(objAddress) {}
54};
55
56class RelocationEntry {
57public:
58  unsigned    SectionID;  // Section the relocation is contained in.
59  uintptr_t   Offset;     // Offset into the section for the relocation.
60  uint32_t    Data;       // Relocatino data. Including type of relocation
61                          // and another flags and parameners from
62  intptr_t    Addend;     // Addend encoded in the instruction itself, if any,
63                          // plus the offset into the source section for
64                          // the symbol once the relocation is resolvable.
65  RelocationEntry(unsigned id, uint64_t offset, uint32_t data, int64_t addend)
66    : SectionID(id), Offset(offset), Data(data), Addend(addend) {}
67};
68
69// Raw relocation data from object file
70class ObjRelocationInfo {
71public:
72  unsigned  SectionID;
73  uint64_t  Offset;
74  SymbolRef Symbol;
75  uint64_t  Type;
76  int64_t   AdditionalInfo;
77};
78
79class RelocationValueRef {
80public:
81  unsigned  SectionID;
82  intptr_t  Addend;
83  const char *SymbolName;
84  RelocationValueRef(): SectionID(0), Addend(0), SymbolName(0) {}
85
86  inline bool operator==(const RelocationValueRef &Other) const {
87    return std::memcmp(this, &Other, sizeof(RelocationValueRef)) == 0;
88  }
89  inline bool operator <(const RelocationValueRef &Other) const {
90    return std::memcmp(this, &Other, sizeof(RelocationValueRef)) < 0;
91  }
92};
93
94class RuntimeDyldImpl {
95protected:
96  // The MemoryManager to load objects into.
97  RTDyldMemoryManager *MemMgr;
98
99  // A list of emmitted sections.
100  typedef SmallVector<SectionEntry, 64> SectionList;
101  SectionList Sections;
102
103  // Keep a map of sections from object file to the SectionID which
104  // references it.
105  typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
106
107  // Master symbol table. As modules are loaded and external symbols are
108  // resolved, their addresses are stored here as a SectionID/Offset pair.
109  typedef std::pair<unsigned, uintptr_t> SymbolLoc;
110  StringMap<SymbolLoc> SymbolTable;
111  typedef DenseMap<const char*, SymbolLoc> LocalSymbolMap;
112
113  // Keep a map of common symbols to their sizes
114  typedef std::map<SymbolRef, unsigned> CommonSymbolMap;
115
116  // For each symbol, keep a list of relocations based on it. Anytime
117  // its address is reassigned (the JIT re-compiled the function, e.g.),
118  // the relocations get re-resolved.
119  // The symbol (or section) the relocation is sourced from is the Key
120  // in the relocation list where it's stored.
121  typedef SmallVector<RelocationEntry, 64> RelocationList;
122  // Relocations to sections already loaded. Indexed by SectionID which is the
123  // source of the address. The target where the address will be writen is
124  // SectionID/Offset in the relocation itself.
125  DenseMap<unsigned, RelocationList> Relocations;
126  // Relocations to external symbols that are not yet resolved.
127  // Indexed by symbol name.
128  StringMap<RelocationList> SymbolRelocations;
129
130  typedef std::map<RelocationValueRef, uintptr_t> StubMap;
131
132  Triple::ArchType Arch;
133
134  inline unsigned getMaxStubSize() {
135    if (Arch == Triple::arm || Arch == Triple::thumb)
136      return 8; // 32-bit instruction and 32-bit address
137    else
138      return 0;
139  }
140
141  bool HasError;
142  std::string ErrorStr;
143
144  // Set the error state and record an error string.
145  bool Error(const Twine &Msg) {
146    ErrorStr = Msg.str();
147    HasError = true;
148    return true;
149  }
150
151  uint8_t *getSectionAddress(unsigned SectionID) {
152    return (uint8_t*)Sections[SectionID].Address;
153  }
154
155  /// \brief Emits a section containing common symbols.
156  /// \return SectionID.
157  unsigned emitCommonSymbols(const CommonSymbolMap &Map,
158                             uint64_t TotalSize,
159                             LocalSymbolMap &Symbols);
160
161  /// \brief Emits section data from the object file to the MemoryManager.
162  /// \param IsCode if it's true then allocateCodeSection() will be
163  ///        used for emmits, else allocateDataSection() will be used.
164  /// \return SectionID.
165  unsigned emitSection(const SectionRef &Section, bool IsCode);
166
167  /// \brief Find Section in LocalSections. If the secton is not found - emit
168  ///        it and store in LocalSections.
169  /// \param IsCode if it's true then allocateCodeSection() will be
170  ///        used for emmits, else allocateDataSection() will be used.
171  /// \return SectionID.
172  unsigned findOrEmitSection(const SectionRef &Section, bool IsCode,
173                             ObjSectionToIDMap &LocalSections);
174
175  /// \brief If Value.SymbolName is NULL then store relocation to the
176  ///        Relocations, else store it in the SymbolRelocations.
177  void AddRelocation(const RelocationValueRef &Value, unsigned SectionID,
178                     uintptr_t Offset, uint32_t RelType);
179
180  /// \brief Emits long jump instruction to Addr.
181  /// \return Pointer to the memory area for emitting target address.
182  uint8_t* createStubFunction(uint8_t *Addr);
183
184  /// \brief Resolves relocations from Relocs list with address from Value.
185  void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
186  void resolveRelocationEntry(const RelocationEntry &RE, uint64_t Value);
187
188  /// \brief A object file specific relocation resolver
189  /// \param Address Address to apply the relocation action
190  /// \param Value Target symbol address to apply the relocation action
191  /// \param Type object file specific relocation type
192  /// \param Addend A constant addend used to compute the value to be stored
193  ///        into the relocatable field
194  virtual void resolveRelocation(uint8_t *LocalAddress,
195                                 uint64_t FinalAddress,
196                                 uint64_t Value,
197                                 uint32_t Type,
198                                 int64_t Addend) = 0;
199
200  /// \brief Parses the object file relocation and store it to Relocations
201  ///        or SymbolRelocations. Its depend from object file type.
202  virtual void processRelocationRef(const ObjRelocationInfo &Rel,
203                                    const ObjectFile &Obj,
204                                    ObjSectionToIDMap &ObjSectionToID,
205                                    LocalSymbolMap &Symbols, StubMap &Stubs) = 0;
206
207  void resolveSymbols();
208public:
209  RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
210
211  virtual ~RuntimeDyldImpl();
212
213  bool loadObject(const MemoryBuffer *InputBuffer);
214
215  void *getSymbolAddress(StringRef Name) {
216    // FIXME: Just look up as a function for now. Overly simple of course.
217    // Work in progress.
218    if (SymbolTable.find(Name) == SymbolTable.end())
219      return 0;
220    SymbolLoc Loc = SymbolTable.lookup(Name);
221    return getSectionAddress(Loc.first) + Loc.second;
222  }
223
224  void resolveRelocations();
225
226  void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
227
228  void mapSectionAddress(void *LocalAddress, uint64_t TargetAddress);
229
230  // Is the linker in an error state?
231  bool hasError() { return HasError; }
232
233  // Mark the error condition as handled and continue.
234  void clearError() { HasError = false; }
235
236  // Get the error message.
237  StringRef getErrorString() { return ErrorStr; }
238
239  virtual bool isCompatibleFormat(const MemoryBuffer *InputBuffer) const = 0;
240
241};
242
243} // end namespace llvm
244
245
246#endif
247