include/llvm/ExecutionEngine/RuntimeDyld.h

   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/STLExtras.h"
  17 #include "llvm/ADT/StringRef.h"
  18 #include "llvm/DebugInfo/DIContext.h"
  19 #include "llvm/ExecutionEngine/JITSymbol.h"
  20 #include "llvm/Object/ObjectFile.h"
  21 #include "llvm/Support/Error.h"
  22 #include <algorithm>
  23 #include <cassert>
  24 #include <cstddef>
  25 #include <cstdint>
  26 #include <map>
  27 #include <memory>
  28 #include <string>
  29 #include <system_error>
  30
  31 namespace llvm {
  32
  33 namespace object {
  34
  35 template <typename T> class OwningBinary;
  36
  37 } // end namespace object
  38
  39 /// Base class for errors originating in RuntimeDyld, e.g. missing relocation
  40 /// support.
  41 class RuntimeDyldError : public ErrorInfo<RuntimeDyldError> {
  42 public:
  43   static char ID;
  44
  45   RuntimeDyldError(std::string ErrMsg) : ErrMsg(std::move(ErrMsg)) {}
  46
  47   void log(raw_ostream &OS) const override;
  48   const std::string &getErrorMessage() const { return ErrMsg; }
  49   std::error_code convertToErrorCode() const override;
  50
  51 private:
  52   std::string ErrMsg;
  53 };
  54
  55 class RuntimeDyldImpl;
  56
  57 class RuntimeDyld {
  58 protected:
  59   // Change the address associated with a section when resolving relocations.
  60   // Any relocations already associated with the symbol will be re-resolved.
  61   void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
  62
  63 public:
  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     /// 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   /// 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 section ID for the section containing the given symbol.
 189   unsigned getSymbolSectionID(StringRef Name) const;
 190
 191   /// Get the target address and flags for the named symbol.
 192   /// This address is the one used for relocation.
 193   JITEvaluatedSymbol getSymbol(StringRef Name) const;
 194
 195   /// Returns a copy of the symbol table. This can be used by on-finalized
 196   /// callbacks to extract the symbol table before throwing away the
 197   /// RuntimeDyld instance. Because the map keys (StringRefs) are backed by
 198   /// strings inside the RuntimeDyld instance, the map should be processed
 199   /// before the RuntimeDyld instance is discarded.
 200   std::map<StringRef, JITEvaluatedSymbol> getSymbolTable() const;
 201
 202   /// Resolve the relocations for all symbols we currently know about.
 203   void resolveRelocations();
 204
 205   /// Map a section to its target address space value.
 206   /// Map the address of a JIT section as returned from the memory manager
 207   /// to the address in the target process as the running code will see it.
 208   /// This is the address which will be used for relocation resolution.
 209   void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
 210
 211   /// Returns the section's working memory.
 212   StringRef getSectionContent(unsigned SectionID) const;
 213
 214   /// If the section was loaded, return the section's load address,
 215   /// otherwise return None.
 216   uint64_t getSectionLoadAddress(unsigned SectionID) const;
 217
 218   /// Set the NotifyStubEmitted callback. This is used for debugging
 219   /// purposes. A callback is made for each stub that is generated.
 220   void setNotifyStubEmitted(NotifyStubEmittedFunction NotifyStubEmitted) {
 221     this->NotifyStubEmitted = std::move(NotifyStubEmitted);
 222   }
 223
 224   /// Register any EH frame sections that have been loaded but not previously
 225   /// registered with the memory manager.  Note, RuntimeDyld is responsible
 226   /// for identifying the EH frame and calling the memory manager with the
 227   /// EH frame section data.  However, the memory manager itself will handle
 228   /// the actual target-specific EH frame registration.
 229   void registerEHFrames();
 230
 231   void deregisterEHFrames();
 232
 233   bool hasError();
 234   StringRef getErrorString();
 235
 236   /// By default, only sections that are "required for execution" are passed to
 237   /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true'
 238   /// to this method will cause RuntimeDyld to pass all sections to its
 239   /// memory manager regardless of whether they are "required to execute" in the
 240   /// usual sense. This is useful for inspecting metadata sections that may not
 241   /// contain relocations, E.g. Debug info, stackmaps.
 242   ///
 243   /// Must be called before the first object file is loaded.
 244   void setProcessAllSections(bool ProcessAllSections) {
 245     assert(!Dyld && "setProcessAllSections must be called before loadObject.");
 246     this->ProcessAllSections = ProcessAllSections;
 247   }
 248
 249   /// Perform all actions needed to make the code owned by this RuntimeDyld
 250   /// instance executable:
 251   ///
 252   /// 1) Apply relocations.
 253   /// 2) Register EH frames.
 254   /// 3) Update memory permissions*.
 255   ///
 256   /// * Finalization is potentially recursive**, and the 3rd step will only be
 257   ///   applied by the outermost call to finalize. This allows different
 258   ///   RuntimeDyld instances to share a memory manager without the innermost
 259   ///   finalization locking the memory and causing relocation fixup errors in
 260   ///   outer instances.
 261   ///
 262   /// ** Recursive finalization occurs when one RuntimeDyld instances needs the
 263   ///   address of a symbol owned by some other instance in order to apply
 264   ///   relocations.
 265   ///
 266   void finalizeWithMemoryManagerLocking();
 267
 268 private:
 269   friend void
 270   jitLinkForORC(object::ObjectFile &Obj,
 271                 std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
 272                 RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver,
 273                 bool ProcessAllSections,
 274                 std::function<Error(std::unique_ptr<LoadedObjectInfo>,
 275                                     std::map<StringRef, JITEvaluatedSymbol>)>
 276                     OnLoaded,
 277                 std::function<void(Error)> OnEmitted);
 278
 279   // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public
 280   // interface.
 281   std::unique_ptr<RuntimeDyldImpl> Dyld;
 282   MemoryManager &MemMgr;
 283   JITSymbolResolver &Resolver;
 284   bool ProcessAllSections;
 285   NotifyStubEmittedFunction NotifyStubEmitted;
 286 };
 287
 288 // Asynchronous JIT link for ORC.
 289 //
 290 // Warning: This API is experimental and probably should not be used by anyone
 291 // but ORC's RTDyldObjectLinkingLayer2. Internally it constructs a RuntimeDyld
 292 // instance and uses continuation passing to perform the fix-up and finalize
 293 // steps asynchronously.
 294 void jitLinkForORC(object::ObjectFile &Obj,
 295                    std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
 296                    RuntimeDyld::MemoryManager &MemMgr,
 297                    JITSymbolResolver &Resolver, bool ProcessAllSections,
 298                    std::function<Error(std::unique_ptr<LoadedObjectInfo>,
 299                                        std::map<StringRef, JITEvaluatedSymbol>)>
 300                        OnLoaded,
 301                    std::function<void(Error)> OnEmitted);
 302
 303 } // end namespace llvm
 304
 305 #endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H