1 //===- RuntimeDyld.h - Run-time dynamic linker for MC-JIT -------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Interface for the runtime dynamic linker facilities of the MC-JIT. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 14 #define LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 15 16 #include "llvm/ADT/FunctionExtras.h" 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 RuntimeDyldImpl; 57 58 class RuntimeDyld { 59 public: 60 // Change the address associated with a section when resolving relocations. 61 // Any relocations already associated with the symbol will be re-resolved. 62 void reassignSectionAddress(unsigned SectionID, uint64_t Addr); 63 64 using NotifyStubEmittedFunction = std::function<void( 65 StringRef FileName, StringRef SectionName, StringRef SymbolName, 66 unsigned SectionID, uint32_t StubOffset)>; 67 68 /// 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 /// 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 /// Override to return false to tell LLVM no stub space will be needed. 133 /// This requires some guarantees depending on architecuture, but when 134 /// you know what you are doing it saves allocated space. 135 virtual bool allowStubAllocation() const { return true; } 136 137 /// Register the EH frames with the runtime so that c++ exceptions work. 138 /// 139 /// \p Addr parameter provides the local address of the EH frame section 140 /// data, while \p LoadAddr provides the address of the data in the target 141 /// address space. If the section has not been remapped (which will usually 142 /// be the case for local execution) these two values will be the same. 143 virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, 144 size_t Size) = 0; 145 virtual void deregisterEHFrames() = 0; 146 147 /// This method is called when object loading is complete and section page 148 /// permissions can be applied. It is up to the memory manager implementation 149 /// to decide whether or not to act on this method. The memory manager will 150 /// typically allocate all sections as read-write and then apply specific 151 /// permissions when this method is called. Code sections cannot be executed 152 /// until this function has been called. In addition, any cache coherency 153 /// operations needed to reliably use the memory are also performed. 154 /// 155 /// Returns true if an error occurred, false otherwise. 156 virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0; 157 158 /// This method is called after an object has been loaded into memory but 159 /// before relocations are applied to the loaded sections. 160 /// 161 /// Memory managers which are preparing code for execution in an external 162 /// address space can use this call to remap the section addresses for the 163 /// newly loaded object. 164 /// 165 /// For clients that do not need access to an ExecutionEngine instance this 166 /// method should be preferred to its cousin 167 /// MCJITMemoryManager::notifyObjectLoaded as this method is compatible with 168 /// ORC JIT stacks. 169 virtual void notifyObjectLoaded(RuntimeDyld &RTDyld, 170 const object::ObjectFile &Obj) {} 171 172 private: 173 virtual void anchor(); 174 175 bool FinalizationLocked = false; 176 }; 177 178 /// Construct a RuntimeDyld instance. 179 RuntimeDyld(MemoryManager &MemMgr, JITSymbolResolver &Resolver); 180 RuntimeDyld(const RuntimeDyld &) = delete; 181 RuntimeDyld &operator=(const RuntimeDyld &) = delete; 182 ~RuntimeDyld(); 183 184 /// Add the referenced object file to the list of objects to be loaded and 185 /// relocated. 186 std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O); 187 188 /// Get the address of our local copy of the symbol. This may or may not 189 /// be the address used for relocation (clients can copy the data around 190 /// and resolve relocatons based on where they put it). 191 void *getSymbolLocalAddress(StringRef Name) const; 192 193 /// Get the section ID for the section containing the given symbol. 194 unsigned getSymbolSectionID(StringRef Name) const; 195 196 /// Get the target address and flags for the named symbol. 197 /// This address is the one used for relocation. 198 JITEvaluatedSymbol getSymbol(StringRef Name) const; 199 200 /// Returns a copy of the symbol table. This can be used by on-finalized 201 /// callbacks to extract the symbol table before throwing away the 202 /// RuntimeDyld instance. Because the map keys (StringRefs) are backed by 203 /// strings inside the RuntimeDyld instance, the map should be processed 204 /// before the RuntimeDyld instance is discarded. 205 std::map<StringRef, JITEvaluatedSymbol> getSymbolTable() const; 206 207 /// Resolve the relocations for all symbols we currently know about. 208 void resolveRelocations(); 209 210 /// Map a section to its target address space value. 211 /// Map the address of a JIT section as returned from the memory manager 212 /// to the address in the target process as the running code will see it. 213 /// This is the address which will be used for relocation resolution. 214 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress); 215 216 /// Returns the section's working memory. 217 StringRef getSectionContent(unsigned SectionID) const; 218 219 /// If the section was loaded, return the section's load address, 220 /// otherwise return None. 221 uint64_t getSectionLoadAddress(unsigned SectionID) const; 222 223 /// Set the NotifyStubEmitted callback. This is used for debugging 224 /// purposes. A callback is made for each stub that is generated. 225 void setNotifyStubEmitted(NotifyStubEmittedFunction NotifyStubEmitted) { 226 this->NotifyStubEmitted = std::move(NotifyStubEmitted); 227 } 228 229 /// Register any EH frame sections that have been loaded but not previously 230 /// registered with the memory manager. Note, RuntimeDyld is responsible 231 /// for identifying the EH frame and calling the memory manager with the 232 /// EH frame section data. However, the memory manager itself will handle 233 /// the actual target-specific EH frame registration. 234 void registerEHFrames(); 235 236 void deregisterEHFrames(); 237 238 bool hasError(); 239 StringRef getErrorString(); 240 241 /// By default, only sections that are "required for execution" are passed to 242 /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true' 243 /// to this method will cause RuntimeDyld to pass all sections to its 244 /// memory manager regardless of whether they are "required to execute" in the 245 /// usual sense. This is useful for inspecting metadata sections that may not 246 /// contain relocations, E.g. Debug info, stackmaps. 247 /// 248 /// Must be called before the first object file is loaded. 249 void setProcessAllSections(bool ProcessAllSections) { 250 assert(!Dyld && "setProcessAllSections must be called before loadObject."); 251 this->ProcessAllSections = ProcessAllSections; 252 } 253 254 /// Perform all actions needed to make the code owned by this RuntimeDyld 255 /// instance executable: 256 /// 257 /// 1) Apply relocations. 258 /// 2) Register EH frames. 259 /// 3) Update memory permissions*. 260 /// 261 /// * Finalization is potentially recursive**, and the 3rd step will only be 262 /// applied by the outermost call to finalize. This allows different 263 /// RuntimeDyld instances to share a memory manager without the innermost 264 /// finalization locking the memory and causing relocation fixup errors in 265 /// outer instances. 266 /// 267 /// ** Recursive finalization occurs when one RuntimeDyld instances needs the 268 /// address of a symbol owned by some other instance in order to apply 269 /// relocations. 270 /// 271 void finalizeWithMemoryManagerLocking(); 272 273 private: 274 friend void jitLinkForORC( 275 object::OwningBinary<object::ObjectFile> O, 276 RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver, 277 bool ProcessAllSections, 278 unique_function<Error(const object::ObjectFile &Obj, LoadedObjectInfo &, 279 std::map<StringRef, JITEvaluatedSymbol>)> 280 OnLoaded, 281 unique_function<void(object::OwningBinary<object::ObjectFile> O, 282 std::unique_ptr<LoadedObjectInfo>, Error)> 283 OnEmitted); 284 285 // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public 286 // interface. 287 std::unique_ptr<RuntimeDyldImpl> Dyld; 288 MemoryManager &MemMgr; 289 JITSymbolResolver &Resolver; 290 bool ProcessAllSections; 291 NotifyStubEmittedFunction NotifyStubEmitted; 292 }; 293 294 // Asynchronous JIT link for ORC. 295 // 296 // Warning: This API is experimental and probably should not be used by anyone 297 // but ORC's RTDyldObjectLinkingLayer2. Internally it constructs a RuntimeDyld 298 // instance and uses continuation passing to perform the fix-up and finalize 299 // steps asynchronously. 300 void jitLinkForORC( 301 object::OwningBinary<object::ObjectFile> O, 302 RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver, 303 bool ProcessAllSections, 304 unique_function<Error(const object::ObjectFile &Obj, 305 RuntimeDyld::LoadedObjectInfo &, 306 std::map<StringRef, JITEvaluatedSymbol>)> 307 OnLoaded, 308 unique_function<void(object::OwningBinary<object::ObjectFile>, 309 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>, Error)> 310 OnEmitted); 311 312 } // end namespace llvm 313 314 #endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 315