1//===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- 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// This file contains the declaration of a section-based memory manager used by
11// the MCJIT execution engine and RuntimeDyld.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
16#define LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
17
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ExecutionEngine/RuntimeDyld.h"
20#include "llvm/Support/ErrorHandling.h"
21#include "llvm/Support/Memory.h"
22
23namespace llvm {
24/// This is a simple memory manager which implements the methods called by
25/// the RuntimeDyld class to allocate memory for section-based loading of
26/// objects, usually those generated by the MCJIT execution engine.
27///
28/// This memory manager allocates all section memory as read-write.  The
29/// RuntimeDyld will copy JITed section memory into these allocated blocks
30/// and perform any necessary linking and relocations.
31///
32/// Any client using this memory manager MUST ensure that section-specific
33/// page permissions have been applied before attempting to execute functions
34/// in the JITed object.  Permissions can be applied either by calling
35/// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
36/// directly.  Clients of MCJIT should call MCJIT::finalizeObject.
37class SectionMemoryManager : public RTDyldMemoryManager {
38  SectionMemoryManager(const SectionMemoryManager&) LLVM_DELETED_FUNCTION;
39  void operator=(const SectionMemoryManager&) LLVM_DELETED_FUNCTION;
40
41public:
42  SectionMemoryManager() { }
43  virtual ~SectionMemoryManager();
44
45  /// \brief Allocates a memory block of (at least) the given size suitable for
46  /// executable code.
47  ///
48  /// The value of \p Alignment must be a power of two.  If \p Alignment is zero
49  /// a default alignment of 16 will be used.
50  uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
51                               unsigned SectionID,
52                               StringRef SectionName) override;
53
54  /// \brief Allocates a memory block of (at least) the given size suitable for
55  /// executable code.
56  ///
57  /// The value of \p Alignment must be a power of two.  If \p Alignment is zero
58  /// a default alignment of 16 will be used.
59  uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
60                               unsigned SectionID, StringRef SectionName,
61                               bool isReadOnly) override;
62
63  /// \brief Update section-specific memory permissions and other attributes.
64  ///
65  /// This method is called when object loading is complete and section page
66  /// permissions can be applied.  It is up to the memory manager implementation
67  /// to decide whether or not to act on this method.  The memory manager will
68  /// typically allocate all sections as read-write and then apply specific
69  /// permissions when this method is called.  Code sections cannot be executed
70  /// until this function has been called.  In addition, any cache coherency
71  /// operations needed to reliably use the memory are also performed.
72  ///
73  /// \returns true if an error occurred, false otherwise.
74  bool finalizeMemory(std::string *ErrMsg = nullptr) override;
75
76  /// \brief Invalidate instruction cache for code sections.
77  ///
78  /// Some platforms with separate data cache and instruction cache require
79  /// explicit cache flush, otherwise JIT code manipulations (like resolved
80  /// relocations) will get to the data cache but not to the instruction cache.
81  ///
82  /// This method is called from finalizeMemory.
83  virtual void invalidateInstructionCache();
84
85private:
86  struct MemoryGroup {
87      SmallVector<sys::MemoryBlock, 16> AllocatedMem;
88      SmallVector<sys::MemoryBlock, 16> FreeMem;
89      sys::MemoryBlock Near;
90  };
91
92  uint8_t *allocateSection(MemoryGroup &MemGroup, uintptr_t Size,
93                           unsigned Alignment);
94
95  std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
96                                              unsigned Permissions);
97
98  MemoryGroup CodeMem;
99  MemoryGroup RWDataMem;
100  MemoryGroup RODataMem;
101};
102
103}
104
105#endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
106
107