1 //===- RuntimeDyld.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 runtime dynamic linker facilities of the MC-JIT. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 15 #define LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 16 17 #include "llvm/ADT/STLExtras.h" 18 #include "llvm/ADT/StringRef.h" 19 #include "llvm/DebugInfo/DIContext.h" 20 #include "llvm/ExecutionEngine/JITSymbol.h" 21 #include "llvm/Object/ObjectFile.h" 22 #include "llvm/Support/Error.h" 23 #include <algorithm> 24 #include <cassert> 25 #include <cstddef> 26 #include <cstdint> 27 #include <map> 28 #include <memory> 29 #include <string> 30 #include <system_error> 31 32 namespace llvm { 33 34 namespace object { 35 36 template <typename T> class OwningBinary; 37 38 } // end namespace object 39 40 /// Base class for errors originating in RuntimeDyld, e.g. missing relocation 41 /// support. 42 class RuntimeDyldError : public ErrorInfo<RuntimeDyldError> { 43 public: 44 static char ID; 45 46 RuntimeDyldError(std::string ErrMsg) : ErrMsg(std::move(ErrMsg)) {} 47 48 void log(raw_ostream &OS) const override; 49 const std::string &getErrorMessage() const { return ErrMsg; } 50 std::error_code convertToErrorCode() const override; 51 52 private: 53 std::string ErrMsg; 54 }; 55 56 class RuntimeDyldCheckerImpl; 57 class RuntimeDyldImpl; 58 59 class RuntimeDyld { 60 friend class RuntimeDyldCheckerImpl; 61 62 protected: 63 // Change the address associated with a section when resolving relocations. 64 // Any relocations already associated with the symbol will be re-resolved. 65 void reassignSectionAddress(unsigned SectionID, uint64_t Addr); 66 67 public: 68 /// \brief Information about the loaded object. 69 class LoadedObjectInfo : public llvm::LoadedObjectInfo { 70 friend class RuntimeDyldImpl; 71 72 public: 73 using ObjSectionToIDMap = std::map<object::SectionRef, unsigned>; 74 75 LoadedObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap) 76 : RTDyld(RTDyld), ObjSecToIDMap(std::move(ObjSecToIDMap)) {} 77 78 virtual object::OwningBinary<object::ObjectFile> 79 getObjectForDebug(const object::ObjectFile &Obj) const = 0; 80 81 uint64_t 82 getSectionLoadAddress(const object::SectionRef &Sec) const override; 83 84 protected: 85 virtual void anchor(); 86 87 RuntimeDyldImpl &RTDyld; 88 ObjSectionToIDMap ObjSecToIDMap; 89 }; 90 91 /// \brief Memory Management. 92 class MemoryManager { 93 friend class RuntimeDyld; 94 95 public: 96 MemoryManager() = default; 97 virtual ~MemoryManager() = default; 98 99 /// Allocate a memory block of (at least) the given size suitable for 100 /// executable code. The SectionID is a unique identifier assigned by the 101 /// RuntimeDyld instance, and optionally recorded by the memory manager to 102 /// access a loaded section. 103 virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment, 104 unsigned SectionID, 105 StringRef SectionName) = 0; 106 107 /// Allocate a memory block of (at least) the given size suitable for data. 108 /// The SectionID is a unique identifier assigned by the JIT engine, and 109 /// optionally recorded by the memory manager to access a loaded section. 110 virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment, 111 unsigned SectionID, 112 StringRef SectionName, 113 bool IsReadOnly) = 0; 114 115 /// Inform the memory manager about the total amount of memory required to 116 /// allocate all sections to be loaded: 117 /// \p CodeSize - the total size of all code sections 118 /// \p DataSizeRO - the total size of all read-only data sections 119 /// \p DataSizeRW - the total size of all read-write data sections 120 /// 121 /// Note that by default the callback is disabled. To enable it 122 /// redefine the method needsToReserveAllocationSpace to return true. 123 virtual void reserveAllocationSpace(uintptr_t CodeSize, uint32_t CodeAlign, 124 uintptr_t RODataSize, 125 uint32_t RODataAlign, 126 uintptr_t RWDataSize, 127 uint32_t RWDataAlign) {} 128 129 /// Override to return true to enable the reserveAllocationSpace callback. 130 virtual bool needsToReserveAllocationSpace() { return false; } 131 132 /// Register the EH frames with the runtime so that c++ exceptions work. 133 /// 134 /// \p Addr parameter provides the local address of the EH frame section 135 /// data, while \p LoadAddr provides the address of the data in the target 136 /// address space. If the section has not been remapped (which will usually 137 /// be the case for local execution) these two values will be the same. 138 virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, 139 size_t Size) = 0; 140 virtual void deregisterEHFrames() = 0; 141 142 /// This method is called when object loading is complete and section page 143 /// permissions can be applied. It is up to the memory manager implementation 144 /// to decide whether or not to act on this method. The memory manager will 145 /// typically allocate all sections as read-write and then apply specific 146 /// permissions when this method is called. Code sections cannot be executed 147 /// until this function has been called. In addition, any cache coherency 148 /// operations needed to reliably use the memory are also performed. 149 /// 150 /// Returns true if an error occurred, false otherwise. 151 virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0; 152 153 /// This method is called after an object has been loaded into memory but 154 /// before relocations are applied to the loaded sections. 155 /// 156 /// Memory managers which are preparing code for execution in an external 157 /// address space can use this call to remap the section addresses for the 158 /// newly loaded object. 159 /// 160 /// For clients that do not need access to an ExecutionEngine instance this 161 /// method should be preferred to its cousin 162 /// MCJITMemoryManager::notifyObjectLoaded as this method is compatible with 163 /// ORC JIT stacks. 164 virtual void notifyObjectLoaded(RuntimeDyld &RTDyld, 165 const object::ObjectFile &Obj) {} 166 167 private: 168 virtual void anchor(); 169 170 bool FinalizationLocked = false; 171 }; 172 173 /// \brief Construct a RuntimeDyld instance. 174 RuntimeDyld(MemoryManager &MemMgr, JITSymbolResolver &Resolver); 175 RuntimeDyld(const RuntimeDyld &) = delete; 176 RuntimeDyld &operator=(const RuntimeDyld &) = delete; 177 ~RuntimeDyld(); 178 179 /// Add the referenced object file to the list of objects to be loaded and 180 /// relocated. 181 std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O); 182 183 /// Get the address of our local copy of the symbol. This may or may not 184 /// be the address used for relocation (clients can copy the data around 185 /// and resolve relocatons based on where they put it). 186 void *getSymbolLocalAddress(StringRef Name) const; 187 188 /// Get the target address and flags for the named symbol. 189 /// This address is the one used for relocation. 190 JITEvaluatedSymbol getSymbol(StringRef Name) const; 191 192 /// Resolve the relocations for all symbols we currently know about. 193 void resolveRelocations(); 194 195 /// Map a section to its target address space value. 196 /// Map the address of a JIT section as returned from the memory manager 197 /// to the address in the target process as the running code will see it. 198 /// This is the address which will be used for relocation resolution. 199 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress); 200 201 /// Register any EH frame sections that have been loaded but not previously 202 /// registered with the memory manager. Note, RuntimeDyld is responsible 203 /// for identifying the EH frame and calling the memory manager with the 204 /// EH frame section data. However, the memory manager itself will handle 205 /// the actual target-specific EH frame registration. 206 void registerEHFrames(); 207 208 void deregisterEHFrames(); 209 210 bool hasError(); 211 StringRef getErrorString(); 212 213 /// By default, only sections that are "required for execution" are passed to 214 /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true' 215 /// to this method will cause RuntimeDyld to pass all sections to its 216 /// memory manager regardless of whether they are "required to execute" in the 217 /// usual sense. This is useful for inspecting metadata sections that may not 218 /// contain relocations, E.g. Debug info, stackmaps. 219 /// 220 /// Must be called before the first object file is loaded. 221 void setProcessAllSections(bool ProcessAllSections) { 222 assert(!Dyld && "setProcessAllSections must be called before loadObject."); 223 this->ProcessAllSections = ProcessAllSections; 224 } 225 226 /// Perform all actions needed to make the code owned by this RuntimeDyld 227 /// instance executable: 228 /// 229 /// 1) Apply relocations. 230 /// 2) Register EH frames. 231 /// 3) Update memory permissions*. 232 /// 233 /// * Finalization is potentially recursive**, and the 3rd step will only be 234 /// applied by the outermost call to finalize. This allows different 235 /// RuntimeDyld instances to share a memory manager without the innermost 236 /// finalization locking the memory and causing relocation fixup errors in 237 /// outer instances. 238 /// 239 /// ** Recursive finalization occurs when one RuntimeDyld instances needs the 240 /// address of a symbol owned by some other instance in order to apply 241 /// relocations. 242 /// 243 void finalizeWithMemoryManagerLocking(); 244 245 private: 246 // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public 247 // interface. 248 std::unique_ptr<RuntimeDyldImpl> Dyld; 249 MemoryManager &MemMgr; 250 JITSymbolResolver &Resolver; 251 bool ProcessAllSections; 252 RuntimeDyldCheckerImpl *Checker; 253 }; 254 255 } // end namespace llvm 256 257 #endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 258