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 RuntimeDyldCheckerImpl;
  56 class RuntimeDyldImpl;
  57
  58 class RuntimeDyld {
  59   friend class RuntimeDyldCheckerImpl;
  60
  61 protected:
  62   // Change the address associated with a section when resolving relocations.
  63   // Any relocations already associated with the symbol will be re-resolved.
  64   void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
  65
  66 public:
  67   /// Information about the loaded object.
  68   class LoadedObjectInfo : public llvm::LoadedObjectInfo {
  69     friend class RuntimeDyldImpl;
  70
  71   public:
  72     using ObjSectionToIDMap = std::map<object::SectionRef, unsigned>;
  73
  74     LoadedObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
  75         : RTDyld(RTDyld), ObjSecToIDMap(std::move(ObjSecToIDMap)) {}
  76
  77     virtual object::OwningBinary<object::ObjectFile>
  78     getObjectForDebug(const object::ObjectFile &Obj) const = 0;
  79
  80     uint64_t
  81     getSectionLoadAddress(const object::SectionRef &Sec) const override;
  82
  83   protected:
  84     virtual void anchor();
  85
  86     RuntimeDyldImpl &RTDyld;
  87     ObjSectionToIDMap ObjSecToIDMap;
  88   };
  89
  90   /// Memory Management.
  91   class MemoryManager {
  92     friend class RuntimeDyld;
  93
  94   public:
  95     MemoryManager() = default;
  96     virtual ~MemoryManager() = default;
  97
  98     /// Allocate a memory block of (at least) the given size suitable for
  99     /// executable code. The SectionID is a unique identifier assigned by the
 100     /// RuntimeDyld instance, and optionally recorded by the memory manager to
 101     /// access a loaded section.
 102     virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
 103                                          unsigned SectionID,
 104                                          StringRef SectionName) = 0;
 105
 106     /// Allocate a memory block of (at least) the given size suitable for data.
 107     /// The SectionID is a unique identifier assigned by the JIT engine, and
 108     /// optionally recorded by the memory manager to access a loaded section.
 109     virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
 110                                          unsigned SectionID,
 111                                          StringRef SectionName,
 112                                          bool IsReadOnly) = 0;
 113
 114     /// Inform the memory manager about the total amount of memory required to
 115     /// allocate all sections to be loaded:
 116     /// \p CodeSize - the total size of all code sections
 117     /// \p DataSizeRO - the total size of all read-only data sections
 118     /// \p DataSizeRW - the total size of all read-write data sections
 119     ///
 120     /// Note that by default the callback is disabled. To enable it
 121     /// redefine the method needsToReserveAllocationSpace to return true.
 122     virtual void reserveAllocationSpace(uintptr_t CodeSize, uint32_t CodeAlign,
 123                                         uintptr_t RODataSize,
 124                                         uint32_t RODataAlign,
 125                                         uintptr_t RWDataSize,
 126                                         uint32_t RWDataAlign) {}
 127
 128     /// Override to return true to enable the reserveAllocationSpace callback.
 129     virtual bool needsToReserveAllocationSpace() { return false; }
 130
 131     /// Register the EH frames with the runtime so that c++ exceptions work.
 132     ///
 133     /// \p Addr parameter provides the local address of the EH frame section
 134     /// data, while \p LoadAddr provides the address of the data in the target
 135     /// address space.  If the section has not been remapped (which will usually
 136     /// be the case for local execution) these two values will be the same.
 137     virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
 138                                   size_t Size) = 0;
 139     virtual void deregisterEHFrames() = 0;
 140
 141     /// This method is called when object loading is complete and section page
 142     /// permissions can be applied.  It is up to the memory manager implementation
 143     /// to decide whether or not to act on this method.  The memory manager will
 144     /// typically allocate all sections as read-write and then apply specific
 145     /// permissions when this method is called.  Code sections cannot be executed
 146     /// until this function has been called.  In addition, any cache coherency
 147     /// operations needed to reliably use the memory are also performed.
 148     ///
 149     /// Returns true if an error occurred, false otherwise.
 150     virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0;
 151
 152     /// This method is called after an object has been loaded into memory but
 153     /// before relocations are applied to the loaded sections.
 154     ///
 155     /// Memory managers which are preparing code for execution in an external
 156     /// address space can use this call to remap the section addresses for the
 157     /// newly loaded object.
 158     ///
 159     /// For clients that do not need access to an ExecutionEngine instance this
 160     /// method should be preferred to its cousin
 161     /// MCJITMemoryManager::notifyObjectLoaded as this method is compatible with
 162     /// ORC JIT stacks.
 163     virtual void notifyObjectLoaded(RuntimeDyld &RTDyld,
 164                                     const object::ObjectFile &Obj) {}
 165
 166   private:
 167     virtual void anchor();
 168
 169     bool FinalizationLocked = false;
 170   };
 171
 172   /// Construct a RuntimeDyld instance.
 173   RuntimeDyld(MemoryManager &MemMgr, JITSymbolResolver &Resolver);
 174   RuntimeDyld(const RuntimeDyld &) = delete;
 175   RuntimeDyld &operator=(const RuntimeDyld &) = delete;
 176   ~RuntimeDyld();
 177
 178   /// Add the referenced object file to the list of objects to be loaded and
 179   /// relocated.
 180   std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O);
 181
 182   /// Get the address of our local copy of the symbol. This may or may not
 183   /// be the address used for relocation (clients can copy the data around
 184   /// and resolve relocatons based on where they put it).
 185   void *getSymbolLocalAddress(StringRef Name) const;
 186
 187   /// Get the target address and flags for the named symbol.
 188   /// This address is the one used for relocation.
 189   JITEvaluatedSymbol getSymbol(StringRef Name) const;
 190
 191   /// Returns a copy of the symbol table. This can be used by on-finalized
 192   /// callbacks to extract the symbol table before throwing away the
 193   /// RuntimeDyld instance. Because the map keys (StringRefs) are backed by
 194   /// strings inside the RuntimeDyld instance, the map should be processed
 195   /// before the RuntimeDyld instance is discarded.
 196   std::map<StringRef, JITEvaluatedSymbol> getSymbolTable() const;
 197
 198   /// Resolve the relocations for all symbols we currently know about.
 199   void resolveRelocations();
 200
 201   /// Map a section to its target address space value.
 202   /// Map the address of a JIT section as returned from the memory manager
 203   /// to the address in the target process as the running code will see it.
 204   /// This is the address which will be used for relocation resolution.
 205   void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
 206
 207   /// Register any EH frame sections that have been loaded but not previously
 208   /// registered with the memory manager.  Note, RuntimeDyld is responsible
 209   /// for identifying the EH frame and calling the memory manager with the
 210   /// EH frame section data.  However, the memory manager itself will handle
 211   /// the actual target-specific EH frame registration.
 212   void registerEHFrames();
 213
 214   void deregisterEHFrames();
 215
 216   bool hasError();
 217   StringRef getErrorString();
 218
 219   /// By default, only sections that are "required for execution" are passed to
 220   /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true'
 221   /// to this method will cause RuntimeDyld to pass all sections to its
 222   /// memory manager regardless of whether they are "required to execute" in the
 223   /// usual sense. This is useful for inspecting metadata sections that may not
 224   /// contain relocations, E.g. Debug info, stackmaps.
 225   ///
 226   /// Must be called before the first object file is loaded.
 227   void setProcessAllSections(bool ProcessAllSections) {
 228     assert(!Dyld && "setProcessAllSections must be called before loadObject.");
 229     this->ProcessAllSections = ProcessAllSections;
 230   }
 231
 232   /// Perform all actions needed to make the code owned by this RuntimeDyld
 233   /// instance executable:
 234   ///
 235   /// 1) Apply relocations.
 236   /// 2) Register EH frames.
 237   /// 3) Update memory permissions*.
 238   ///
 239   /// * Finalization is potentially recursive**, and the 3rd step will only be
 240   ///   applied by the outermost call to finalize. This allows different
 241   ///   RuntimeDyld instances to share a memory manager without the innermost
 242   ///   finalization locking the memory and causing relocation fixup errors in
 243   ///   outer instances.
 244   ///
 245   /// ** Recursive finalization occurs when one RuntimeDyld instances needs the
 246   ///   address of a symbol owned by some other instance in order to apply
 247   ///   relocations.
 248   ///
 249   void finalizeWithMemoryManagerLocking();
 250
 251 private:
 252   friend void
 253   jitLinkForORC(object::ObjectFile &Obj,
 254                 std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
 255                 RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver,
 256                 bool ProcessAllSections,
 257                 std::function<Error(std::unique_ptr<LoadedObjectInfo>,
 258                                     std::map<StringRef, JITEvaluatedSymbol>)>
 259                     OnLoaded,
 260                 std::function<void(Error)> OnEmitted);
 261
 262   // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public
 263   // interface.
 264   std::unique_ptr<RuntimeDyldImpl> Dyld;
 265   MemoryManager &MemMgr;
 266   JITSymbolResolver &Resolver;
 267   bool ProcessAllSections;
 268   RuntimeDyldCheckerImpl *Checker;
 269 };
 270
 271 // Asynchronous JIT link for ORC.
 272 //
 273 // Warning: This API is experimental and probably should not be used by anyone
 274 // but ORC's RTDyldObjectLinkingLayer2. Internally it constructs a RuntimeDyld
 275 // instance and uses continuation passing to perform the fix-up and finalize
 276 // steps asynchronously.
 277 void jitLinkForORC(object::ObjectFile &Obj,
 278                    std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
 279                    RuntimeDyld::MemoryManager &MemMgr,
 280                    JITSymbolResolver &Resolver, bool ProcessAllSections,
 281                    std::function<Error(std::unique_ptr<LoadedObjectInfo>,
 282                                        std::map<StringRef, JITEvaluatedSymbol>)>
 283                        OnLoaded,
 284                    std::function<void(Error)> OnEmitted);
 285
 286 } // end namespace llvm
 287
 288 #endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H