Memory.inc revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
1//===- Win32/Memory.cpp - Win32 Memory Implementation -----------*- 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 provides the Win32 specific implementation of various Memory
11// management utilities
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/Support/DataTypes.h"
16#include "llvm/Support/ErrorHandling.h"
17#include "llvm/Support/Process.h"
18
19// The Windows.h header must be the last one included.
20#include "WindowsSupport.h"
21
22namespace {
23
24DWORD getWindowsProtectionFlags(unsigned Flags) {
25  switch (Flags) {
26  // Contrary to what you might expect, the Windows page protection flags
27  // are not a bitwise combination of RWX values
28  case llvm::sys::Memory::MF_READ:
29    return PAGE_READONLY;
30  case llvm::sys::Memory::MF_WRITE:
31    // Note: PAGE_WRITE is not supported by VirtualProtect
32    return PAGE_READWRITE;
33  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
34    return PAGE_READWRITE;
35  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
36    return PAGE_EXECUTE_READ;
37  case llvm::sys::Memory::MF_READ |
38         llvm::sys::Memory::MF_WRITE |
39         llvm::sys::Memory::MF_EXEC:
40    return PAGE_EXECUTE_READWRITE;
41  case llvm::sys::Memory::MF_EXEC:
42    return PAGE_EXECUTE;
43  default:
44    llvm_unreachable("Illegal memory protection flag specified!");
45  }
46  // Provide a default return value as required by some compilers.
47  return PAGE_NOACCESS;
48}
49
50size_t getAllocationGranularity() {
51  SYSTEM_INFO  Info;
52  ::GetSystemInfo(&Info);
53  if (Info.dwPageSize > Info.dwAllocationGranularity)
54    return Info.dwPageSize;
55  else
56    return Info.dwAllocationGranularity;
57}
58
59} // namespace
60
61namespace llvm {
62namespace sys {
63
64//===----------------------------------------------------------------------===//
65//=== WARNING: Implementation here must contain only Win32 specific code
66//===          and must not be UNIX code
67//===----------------------------------------------------------------------===//
68
69MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
70                                         const MemoryBlock *const NearBlock,
71                                         unsigned Flags,
72                                         error_code &EC) {
73  EC = error_code::success();
74  if (NumBytes == 0)
75    return MemoryBlock();
76
77  // While we'd be happy to allocate single pages, the Windows allocation
78  // granularity may be larger than a single page (in practice, it is 64K)
79  // so mapping less than that will create an unreachable fragment of memory.
80  static const size_t Granularity = getAllocationGranularity();
81  const size_t NumBlocks = (NumBytes+Granularity-1)/Granularity;
82
83  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
84                                NearBlock->size()
85                           : 0;
86
87  // If the requested address is not aligned to the allocation granularity,
88  // round up to get beyond NearBlock. VirtualAlloc would have rounded down.
89  if (Start && Start % Granularity != 0)
90    Start += Granularity - Start % Granularity;
91
92  DWORD Protect = getWindowsProtectionFlags(Flags);
93
94  void *PA = ::VirtualAlloc(reinterpret_cast<void*>(Start),
95                            NumBlocks*Granularity,
96                            MEM_RESERVE | MEM_COMMIT, Protect);
97  if (PA == NULL) {
98    if (NearBlock) {
99      // Try again without the NearBlock hint
100      return allocateMappedMemory(NumBytes, NULL, Flags, EC);
101    }
102    EC = error_code(::GetLastError(), system_category());
103    return MemoryBlock();
104  }
105
106  MemoryBlock Result;
107  Result.Address = PA;
108  Result.Size = NumBlocks*Granularity;
109
110  if (Flags & MF_EXEC)
111    Memory::InvalidateInstructionCache(Result.Address, Result.Size);
112
113  return Result;
114}
115
116error_code Memory::releaseMappedMemory(MemoryBlock &M) {
117  if (M.Address == 0 || M.Size == 0)
118    return error_code::success();
119
120  if (!VirtualFree(M.Address, 0, MEM_RELEASE))
121    return error_code(::GetLastError(), system_category());
122
123  M.Address = 0;
124  M.Size = 0;
125
126  return error_code::success();
127}
128
129error_code Memory::protectMappedMemory(const MemoryBlock &M,
130                                       unsigned Flags) {
131  if (M.Address == 0 || M.Size == 0)
132    return error_code::success();
133
134  DWORD Protect = getWindowsProtectionFlags(Flags);
135
136  DWORD OldFlags;
137  if (!VirtualProtect(M.Address, M.Size, Protect, &OldFlags))
138    return error_code(::GetLastError(), system_category());
139
140  if (Flags & MF_EXEC)
141    Memory::InvalidateInstructionCache(M.Address, M.Size);
142
143  return error_code::success();
144}
145
146/// InvalidateInstructionCache - Before the JIT can run a block of code
147/// that has been emitted it must invalidate the instruction cache on some
148/// platforms.
149void Memory::InvalidateInstructionCache(
150    const void *Addr, size_t Len) {
151  FlushInstructionCache(GetCurrentProcess(), Addr, Len);
152}
153
154
155MemoryBlock Memory::AllocateRWX(size_t NumBytes,
156                                const MemoryBlock *NearBlock,
157                                std::string *ErrMsg) {
158  MemoryBlock MB;
159  error_code EC;
160  MB = allocateMappedMemory(NumBytes, NearBlock,
161                            MF_READ|MF_WRITE|MF_EXEC, EC);
162  if (EC != error_code::success() && ErrMsg) {
163    MakeErrMsg(ErrMsg, EC.message());
164  }
165  return MB;
166}
167
168bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
169  error_code EC = releaseMappedMemory(M);
170  if (EC == error_code::success())
171    return false;
172  MakeErrMsg(ErrMsg, EC.message());
173  return true;
174}
175
176static DWORD getProtection(const void *addr) {
177  MEMORY_BASIC_INFORMATION info;
178  if (sizeof(info) == ::VirtualQuery(addr, &info, sizeof(info))) {
179    return info.Protect;
180  }
181  return 0;
182}
183
184bool Memory::setWritable(MemoryBlock &M, std::string *ErrMsg) {
185  if (!setRangeWritable(M.Address, M.Size)) {
186    return MakeErrMsg(ErrMsg, "Cannot set memory to writeable: ");
187  }
188  return true;
189}
190
191bool Memory::setExecutable(MemoryBlock &M, std::string *ErrMsg) {
192  if (!setRangeExecutable(M.Address, M.Size)) {
193    return MakeErrMsg(ErrMsg, "Cannot set memory to executable: ");
194  }
195  return true;
196}
197
198bool Memory::setRangeWritable(const void *Addr, size_t Size) {
199  DWORD prot = getProtection(Addr);
200  if (!prot)
201    return false;
202
203  if (prot == PAGE_EXECUTE || prot == PAGE_EXECUTE_READ) {
204    prot = PAGE_EXECUTE_READWRITE;
205  } else if (prot == PAGE_NOACCESS || prot == PAGE_READONLY) {
206    prot = PAGE_READWRITE;
207  }
208
209  DWORD oldProt;
210  Memory::InvalidateInstructionCache(Addr, Size);
211  return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
212            == TRUE;
213}
214
215bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
216  DWORD prot = getProtection(Addr);
217  if (!prot)
218    return false;
219
220  if (prot == PAGE_NOACCESS) {
221    prot = PAGE_EXECUTE;
222  } else if (prot == PAGE_READONLY) {
223    prot = PAGE_EXECUTE_READ;
224  } else if (prot == PAGE_READWRITE) {
225    prot = PAGE_EXECUTE_READWRITE;
226  }
227
228  DWORD oldProt;
229  Memory::InvalidateInstructionCache(Addr, Size);
230  return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
231            == TRUE;
232}
233
234} // namespace sys
235} // namespace llvm
236