LLVM  9.0.0svn
RuntimeDyld.h
Go to the documentation of this file.
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"
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:
66  unsigned SectionID, uint32_t StubOffset)>;
67 
68  /// Information about the loaded object.
70  friend class RuntimeDyldImpl;
71 
72  public:
73  using ObjSectionToIDMap = std::map<object::SectionRef, unsigned>;
74 
76  : RTDyld(RTDyld), ObjSecToIDMap(std::move(ObjSecToIDMap)) {}
77 
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 
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,
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.
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.
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.
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
271  std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
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.
295  std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
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
virtual void reserveAllocationSpace(uintptr_t CodeSize, uint32_t CodeAlign, uintptr_t RODataSize, uint32_t RODataAlign, uintptr_t RWDataSize, uint32_t RWDataAlign)
Inform the memory manager about the total amount of memory required to allocate all sections to be lo...
Definition: RuntimeDyld.h:123
Information about the loaded object.
Definition: RuntimeDyld.h:69
This class represents lattice values for constants.
Definition: AllocatorList.h:23
amdgpu Simplify well known AMD library false FunctionCallee Value const Twine & Name
This class is the base class for all object file types.
Definition: ObjectFile.h:225
void jitLinkForORC(object::ObjectFile &Obj, std::unique_ptr< MemoryBuffer > UnderlyingBuffer, RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver, bool ProcessAllSections, std::function< Error(std::unique_ptr< LoadedObjectInfo >, std::map< StringRef, JITEvaluatedSymbol >)> OnLoaded, std::function< void(Error)> OnEmitted)
static unsigned getSymbolSectionID(const ObjectFile &O, SymbolRef Sym)
Definition: SymbolSize.cpp:33
void setNotifyStubEmitted(NotifyStubEmittedFunction NotifyStubEmitted)
Set the NotifyStubEmitted callback.
Definition: RuntimeDyld.h:220
Definition: BitVector.h:937
constexpr char SymbolName[]
Key for Kernel::Metadata::mSymbolName.
virtual bool needsToReserveAllocationSpace()
Override to return true to enable the reserveAllocationSpace callback.
Definition: RuntimeDyld.h:130
std::function< void(StringRef FileName, StringRef SectionName, StringRef SymbolName, unsigned SectionID, uint32_t StubOffset)> NotifyStubEmittedFunction
Definition: RuntimeDyld.h:66
RuntimeDyldError(std::string ErrMsg)
Definition: RuntimeDyld.h:45
Expected< const typename ELFT::Sym * > getSymbol(typename ELFT::SymRange Symbols, uint32_t Index)
Definition: ELF.h:334
void setProcessAllSections(bool ProcessAllSections)
By default, only sections that are "required for execution" are passed to the RTDyldMemoryManager, and other sections are discarded.
Definition: RuntimeDyld.h:244
virtual void notifyObjectLoaded(RuntimeDyld &RTDyld, const object::ObjectFile &Obj)
This method is called after an object has been loaded into memory but before relocations are applied ...
Definition: RuntimeDyld.h:164
Interface for looking up the initializer for a variable name, used by Init::resolveReferences.
Definition: Record.h:1856
Symbol resolution interface.
Definition: JITSymbol.h:343
An inferface for inquiring the load address of a loaded object file to be used by the DIContext imple...
Definition: DIContext.h:223
Represents a symbol that has been evaluated to an address already.
Definition: JITSymbol.h:208
Base class for user error types.
Definition: Error.h:344
Base class for errors originating in RuntimeDyld, e.g.
Definition: RuntimeDyld.h:41
uint32_t Size
Definition: Profile.cpp:46
const std::string & getErrorMessage() const
Definition: RuntimeDyld.h:48
std::map< object::SectionRef, unsigned > ObjSectionToIDMap
Definition: RuntimeDyld.h:73
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Lightweight error class with error context and mandatory checking.
Definition: Error.h:157
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:45
print Print MemDeps of function
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
LoadedObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
Definition: RuntimeDyld.h:75
This is a value type class that represents a single section in the list of sections in the object fil...
Definition: ObjectFile.h:80