SectionMemoryManager.h revision 263508 
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
25/// This is a simple memory manager which implements the methods called by
26/// the RuntimeDyld class to allocate memory for section-based loading of
27/// objects, usually those generated by the MCJIT execution engine.
28///
29/// This memory manager allocates all section memory as read-write.  The
30/// RuntimeDyld will copy JITed section memory into these allocated blocks
31/// and perform any necessary linking and relocations.
32///
33/// Any client using this memory manager MUST ensure that section-specific
34/// page permissions have been applied before attempting to execute functions
35/// in the JITed object.  Permissions can be applied either by calling
36/// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
37/// directly.  Clients of MCJIT should call MCJIT::finalizeObject.
38class SectionMemoryManager : public RTDyldMemoryManager {
39  SectionMemoryManager(const SectionMemoryManager&) LLVM_DELETED_FUNCTION;
40  void operator=(const SectionMemoryManager&) LLVM_DELETED_FUNCTION;
41
42public:
43  SectionMemoryManager() { }
44  virtual ~SectionMemoryManager();
45
46  /// \brief Allocates a memory block of (at least) the given size suitable for
47  /// executable code.
48  ///
49  /// The value of \p Alignment must be a power of two.  If \p Alignment is zero
50  /// a default alignment of 16 will be used.
51  virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
52                                       unsigned SectionID,
53                                       StringRef SectionName);
54
55  /// \brief Allocates a memory block of (at least) the given size suitable for
56  /// executable code.
57  ///
58  /// The value of \p Alignment must be a power of two.  If \p Alignment is zero
59  /// a default alignment of 16 will be used.
60  virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
61                                       unsigned SectionID,
62                                       StringRef SectionName,
63                                       bool isReadOnly);
64
65  /// \brief Update section-specific memory permissions and other attributes.
66  ///
67  /// This method is called when object loading is complete and section page
68  /// permissions can be applied.  It is up to the memory manager implementation
69  /// to decide whether or not to act on this method.  The memory manager will
70  /// typically allocate all sections as read-write and then apply specific
71  /// permissions when this method is called.  Code sections cannot be executed
72  /// until this function has been called.  In addition, any cache coherency
73  /// operations needed to reliably use the memory are also performed.
74  ///
75  /// \returns true if an error occurred, false otherwise.
76  virtual bool finalizeMemory(std::string *ErrMsg = 0);
77
78  /// \brief Invalidate instruction cache for code sections.
79  ///
80  /// Some platforms with separate data cache and instruction cache require
81  /// explicit cache flush, otherwise JIT code manipulations (like resolved
82  /// relocations) will get to the data cache but not to the instruction cache.
83  ///
84  /// This method is called from finalizeMemory.
85  virtual void invalidateInstructionCache();
86
87private:
88  struct MemoryGroup {
89      SmallVector<sys::MemoryBlock, 16> AllocatedMem;
90      SmallVector<sys::MemoryBlock, 16> FreeMem;
91      sys::MemoryBlock Near;
92  };
93
94  uint8_t *allocateSection(MemoryGroup &MemGroup, uintptr_t Size,
95                           unsigned Alignment);
96
97  error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
98                                         unsigned Permissions);
99
100  MemoryGroup CodeMem;
101  MemoryGroup RWDataMem;
102  MemoryGroup RODataMem;
103};
104
105}
106
107#endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
108
109