LLVM  4.0.0
Memory.h
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1 //===- llvm/Support/Memory.h - Memory Support -------------------*- 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 declares the llvm::sys::Memory class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_MEMORY_H
15 #define LLVM_SUPPORT_MEMORY_H
16 
17 #include "llvm/Support/DataTypes.h"
18 #include <string>
19 #include <system_error>
20 
21 namespace llvm {
22 namespace sys {
23 
24  /// This class encapsulates the notion of a memory block which has an address
25  /// and a size. It is used by the Memory class (a friend) as the result of
26  /// various memory allocation operations.
27  /// @see Memory
28  /// @brief Memory block abstraction.
29  class MemoryBlock {
30  public:
31  MemoryBlock() : Address(nullptr), Size(0) { }
32  MemoryBlock(void *addr, size_t size) : Address(addr), Size(size) { }
33  void *base() const { return Address; }
34  size_t size() const { return Size; }
35 
36  private:
37  void *Address; ///< Address of first byte of memory area
38  size_t Size; ///< Size, in bytes of the memory area
39  friend class Memory;
40  };
41 
42  /// This class provides various memory handling functions that manipulate
43  /// MemoryBlock instances.
44  /// @since 1.4
45  /// @brief An abstraction for memory operations.
46  class Memory {
47  public:
49  MF_READ = 0x1000000,
50  MF_WRITE = 0x2000000,
51  MF_EXEC = 0x4000000
52  };
53 
54  /// This method allocates a block of memory that is suitable for loading
55  /// dynamically generated code (e.g. JIT). An attempt to allocate
56  /// \p NumBytes bytes of virtual memory is made.
57  /// \p NearBlock may point to an existing allocation in which case
58  /// an attempt is made to allocate more memory near the existing block.
59  /// The actual allocated address is not guaranteed to be near the requested
60  /// address.
61  /// \p Flags is used to set the initial protection flags for the block
62  /// of the memory.
63  /// \p EC [out] returns an object describing any error that occurs.
64  ///
65  /// This method may allocate more than the number of bytes requested. The
66  /// actual number of bytes allocated is indicated in the returned
67  /// MemoryBlock.
68  ///
69  /// The start of the allocated block must be aligned with the
70  /// system allocation granularity (64K on Windows, page size on Linux).
71  /// If the address following \p NearBlock is not so aligned, it will be
72  /// rounded up to the next allocation granularity boundary.
73  ///
74  /// \r a non-null MemoryBlock if the function was successful,
75  /// otherwise a null MemoryBlock is with \p EC describing the error.
76  ///
77  /// @brief Allocate mapped memory.
78  static MemoryBlock allocateMappedMemory(size_t NumBytes,
79  const MemoryBlock *const NearBlock,
80  unsigned Flags,
81  std::error_code &EC);
82 
83  /// This method releases a block of memory that was allocated with the
84  /// allocateMappedMemory method. It should not be used to release any
85  /// memory block allocated any other way.
86  /// \p Block describes the memory to be released.
87  ///
88  /// \r error_success if the function was successful, or an error_code
89  /// describing the failure if an error occurred.
90  ///
91  /// @brief Release mapped memory.
92  static std::error_code releaseMappedMemory(MemoryBlock &Block);
93 
94  /// This method sets the protection flags for a block of memory to the
95  /// state specified by /p Flags. The behavior is not specified if the
96  /// memory was not allocated using the allocateMappedMemory method.
97  /// \p Block describes the memory block to be protected.
98  /// \p Flags specifies the new protection state to be assigned to the block.
99  /// \p ErrMsg [out] returns a string describing any error that occurred.
100  ///
101  /// If \p Flags is MF_WRITE, the actual behavior varies
102  /// with the operating system (i.e. MF_READ | MF_WRITE on Windows) and the
103  /// target architecture (i.e. MF_WRITE -> MF_READ | MF_WRITE on i386).
104  ///
105  /// \r error_success if the function was successful, or an error_code
106  /// describing the failure if an error occurred.
107  ///
108  /// @brief Set memory protection state.
109  static std::error_code protectMappedMemory(const MemoryBlock &Block,
110  unsigned Flags);
111 
112  /// This method allocates a block of Read/Write/Execute memory that is
113  /// suitable for executing dynamically generated code (e.g. JIT). An
114  /// attempt to allocate \p NumBytes bytes of virtual memory is made.
115  /// \p NearBlock may point to an existing allocation in which case
116  /// an attempt is made to allocate more memory near the existing block.
117  ///
118  /// On success, this returns a non-null memory block, otherwise it returns
119  /// a null memory block and fills in *ErrMsg.
120  ///
121  /// @brief Allocate Read/Write/Execute memory.
122  static MemoryBlock AllocateRWX(size_t NumBytes,
123  const MemoryBlock *NearBlock,
124  std::string *ErrMsg = nullptr);
125 
126  /// This method releases a block of Read/Write/Execute memory that was
127  /// allocated with the AllocateRWX method. It should not be used to
128  /// release any memory block allocated any other way.
129  ///
130  /// On success, this returns false, otherwise it returns true and fills
131  /// in *ErrMsg.
132  /// @brief Release Read/Write/Execute memory.
133  static bool ReleaseRWX(MemoryBlock &block, std::string *ErrMsg = nullptr);
134 
135  /// InvalidateInstructionCache - Before the JIT can run a block of code
136  /// that has been emitted it must invalidate the instruction cache on some
137  /// platforms.
138  static void InvalidateInstructionCache(const void *Addr, size_t Len);
139 
140  /// setExecutable - Before the JIT can run a block of code, it has to be
141  /// given read and executable privilege. Return true if it is already r-x
142  /// or the system is able to change its previlege.
143  static bool setExecutable(MemoryBlock &M, std::string *ErrMsg = nullptr);
144 
145  /// setWritable - When adding to a block of code, the JIT may need
146  /// to mark a block of code as RW since the protections are on page
147  /// boundaries, and the JIT internal allocations are not page aligned.
148  static bool setWritable(MemoryBlock &M, std::string *ErrMsg = nullptr);
149 
150  /// setRangeExecutable - Mark the page containing a range of addresses
151  /// as executable.
152  static bool setRangeExecutable(const void *Addr, size_t Size);
153 
154  /// setRangeWritable - Mark the page containing a range of addresses
155  /// as writable.
156  static bool setRangeWritable(const void *Addr, size_t Size);
157  };
158 
159  /// Owning version of MemoryBlock.
161  public:
162  OwningMemoryBlock() = default;
163  explicit OwningMemoryBlock(MemoryBlock M) : M(M) {}
165  M = Other.M;
166  Other.M = MemoryBlock();
167  }
169  M = Other.M;
170  Other.M = MemoryBlock();
171  return *this;
172  }
175  }
176  void *base() const { return M.base(); }
177  size_t size() const { return M.size(); }
178  MemoryBlock getMemoryBlock() const { return M; }
179  private:
180  MemoryBlock M;
181  };
182 
183 }
184 }
185 
186 #endif
static bool setRangeWritable(const void *Addr, size_t Size)
setRangeWritable - Mark the page containing a range of addresses as writable.
This class provides various memory handling functions that manipulate MemoryBlock instances...
Definition: Memory.h:46
static std::error_code releaseMappedMemory(MemoryBlock &Block)
This method releases a block of memory that was allocated with the allocateMappedMemory method...
static MemoryBlock allocateMappedMemory(size_t NumBytes, const MemoryBlock *const NearBlock, unsigned Flags, std::error_code &EC)
This method allocates a block of memory that is suitable for loading dynamically generated code (e...
OwningMemoryBlock(MemoryBlock M)
Definition: Memory.h:163
struct fuzzer::@269 Flags
static void InvalidateInstructionCache(const void *Addr, size_t Len)
InvalidateInstructionCache - Before the JIT can run a block of code that has been emitted it must inv...
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:662
MemoryBlock getMemoryBlock() const
Definition: Memory.h:178
MemoryBlock(void *addr, size_t size)
Definition: Memory.h:32
static bool ReleaseRWX(MemoryBlock &block, std::string *ErrMsg=nullptr)
This method releases a block of Read/Write/Execute memory that was allocated with the AllocateRWX met...
static bool setRangeExecutable(const void *Addr, size_t Size)
setRangeExecutable - Mark the page containing a range of addresses as executable. ...
size_t size() const
Definition: Memory.h:34
OwningMemoryBlock & operator=(OwningMemoryBlock &&Other)
Definition: Memory.h:168
This class encapsulates the notion of a memory block which has an address and a size.
Definition: Memory.h:29
static MemoryBlock AllocateRWX(size_t NumBytes, const MemoryBlock *NearBlock, std::string *ErrMsg=nullptr)
This method allocates a block of Read/Write/Execute memory that is suitable for executing dynamically...
Owning version of MemoryBlock.
Definition: Memory.h:160
OwningMemoryBlock(OwningMemoryBlock &&Other)
Definition: Memory.h:164
void * base() const
Definition: Memory.h:33
void * base() const
Definition: Memory.h:176
static bool setExecutable(MemoryBlock &M, std::string *ErrMsg=nullptr)
setExecutable - Before the JIT can run a block of code, it has to be given read and executable privil...
size_t size() const
Definition: Memory.h:177
static bool setWritable(MemoryBlock &M, std::string *ErrMsg=nullptr)
setWritable - When adding to a block of code, the JIT may need to mark a block of code as RW since th...
static std::error_code protectMappedMemory(const MemoryBlock &Block, unsigned Flags)
This method sets the protection flags for a block of memory to the state specified by /p Flags...