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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#include "llvm/Support/WindowsError.h"
19
20// The Windows.h header must be the last one included.
21#include "WindowsSupport.h"
22
23namespace {
24
25DWORD getWindowsProtectionFlags(unsigned Flags) {
26  switch (Flags) {
27  // Contrary to what you might expect, the Windows page protection flags
28  // are not a bitwise combination of RWX values
29  case llvm::sys::Memory::MF_READ:
30    return PAGE_READONLY;
31  case llvm::sys::Memory::MF_WRITE:
32    // Note: PAGE_WRITE is not supported by VirtualProtect
33    return PAGE_READWRITE;
34  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
35    return PAGE_READWRITE;
36  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
37    return PAGE_EXECUTE_READ;
38  case llvm::sys::Memory::MF_READ |
39         llvm::sys::Memory::MF_WRITE |
40         llvm::sys::Memory::MF_EXEC:
41    return PAGE_EXECUTE_READWRITE;
42  case llvm::sys::Memory::MF_EXEC:
43    return PAGE_EXECUTE;
44  default:
45    llvm_unreachable("Illegal memory protection flag specified!");
46  }
47  // Provide a default return value as required by some compilers.
48  return PAGE_NOACCESS;
49}
50
51size_t getAllocationGranularity() {
52  SYSTEM_INFO  Info;
53  ::GetSystemInfo(&Info);
54  if (Info.dwPageSize > Info.dwAllocationGranularity)
55    return Info.dwPageSize;
56  else
57    return Info.dwAllocationGranularity;
58}
59
60} // namespace
61
62namespace llvm {
63namespace sys {
64
65//===----------------------------------------------------------------------===//
66//=== WARNING: Implementation here must contain only Win32 specific code
67//===          and must not be UNIX code
68//===----------------------------------------------------------------------===//
69
70MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
71                                         const MemoryBlock *const NearBlock,
72                                         unsigned Flags,
73                                         std::error_code &EC) {
74  EC = std::error_code();
75  if (NumBytes == 0)
76    return MemoryBlock();
77
78  // While we'd be happy to allocate single pages, the Windows allocation
79  // granularity may be larger than a single page (in practice, it is 64K)
80  // so mapping less than that will create an unreachable fragment of memory.
81  static const size_t Granularity = getAllocationGranularity();
82  const size_t NumBlocks = (NumBytes+Granularity-1)/Granularity;
83
84  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
85                                NearBlock->size()
86                           : 0;
87
88  // If the requested address is not aligned to the allocation granularity,
89  // round up to get beyond NearBlock. VirtualAlloc would have rounded down.
90  if (Start && Start % Granularity != 0)
91    Start += Granularity - Start % Granularity;
92
93  DWORD Protect = getWindowsProtectionFlags(Flags);
94
95  void *PA = ::VirtualAlloc(reinterpret_cast<void*>(Start),
96                            NumBlocks*Granularity,
97                            MEM_RESERVE | MEM_COMMIT, Protect);
98  if (PA == NULL) {
99    if (NearBlock) {
100      // Try again without the NearBlock hint
101      return allocateMappedMemory(NumBytes, NULL, Flags, EC);
102    }
103    EC = mapWindowsError(::GetLastError());
104    return MemoryBlock();
105  }
106
107  MemoryBlock Result;
108  Result.Address = PA;
109  Result.Size = NumBlocks*Granularity;
110
111  if (Flags & MF_EXEC)
112    Memory::InvalidateInstructionCache(Result.Address, Result.Size);
113
114  return Result;
115}
116
117  std::error_code Memory::releaseMappedMemory(MemoryBlock &M) {
118  if (M.Address == 0 || M.Size == 0)
119    return std::error_code();
120
121  if (!VirtualFree(M.Address, 0, MEM_RELEASE))
122    return mapWindowsError(::GetLastError());
123
124  M.Address = 0;
125  M.Size = 0;
126
127  return std::error_code();
128}
129
130  std::error_code Memory::protectMappedMemory(const MemoryBlock &M,
131                                       unsigned Flags) {
132  if (M.Address == 0 || M.Size == 0)
133    return std::error_code();
134
135  DWORD Protect = getWindowsProtectionFlags(Flags);
136
137  DWORD OldFlags;
138  if (!VirtualProtect(M.Address, M.Size, Protect, &OldFlags))
139    return mapWindowsError(::GetLastError());
140
141  if (Flags & MF_EXEC)
142    Memory::InvalidateInstructionCache(M.Address, M.Size);
143
144  return std::error_code();
145}
146
147/// InvalidateInstructionCache - Before the JIT can run a block of code
148/// that has been emitted it must invalidate the instruction cache on some
149/// platforms.
150void Memory::InvalidateInstructionCache(
151    const void *Addr, size_t Len) {
152  FlushInstructionCache(GetCurrentProcess(), Addr, Len);
153}
154
155
156MemoryBlock Memory::AllocateRWX(size_t NumBytes,
157                                const MemoryBlock *NearBlock,
158                                std::string *ErrMsg) {
159  MemoryBlock MB;
160  std::error_code EC;
161  MB = allocateMappedMemory(NumBytes, NearBlock,
162                            MF_READ|MF_WRITE|MF_EXEC, EC);
163  if (EC != std::error_code() && ErrMsg) {
164    MakeErrMsg(ErrMsg, EC.message());
165  }
166  return MB;
167}
168
169bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
170  std::error_code EC = releaseMappedMemory(M);
171  if (EC == std::error_code())
172    return false;
173  MakeErrMsg(ErrMsg, EC.message());
174  return true;
175}
176
177static DWORD getProtection(const void *addr) {
178  MEMORY_BASIC_INFORMATION info;
179  if (sizeof(info) == ::VirtualQuery(addr, &info, sizeof(info))) {
180    return info.Protect;
181  }
182  return 0;
183}
184
185bool Memory::setWritable(MemoryBlock &M, std::string *ErrMsg) {
186  if (!setRangeWritable(M.Address, M.Size)) {
187    return MakeErrMsg(ErrMsg, "Cannot set memory to writeable: ");
188  }
189  return true;
190}
191
192bool Memory::setExecutable(MemoryBlock &M, std::string *ErrMsg) {
193  if (!setRangeExecutable(M.Address, M.Size)) {
194    return MakeErrMsg(ErrMsg, "Cannot set memory to executable: ");
195  }
196  return true;
197}
198
199bool Memory::setRangeWritable(const void *Addr, size_t Size) {
200  DWORD prot = getProtection(Addr);
201  if (!prot)
202    return false;
203
204  if (prot == PAGE_EXECUTE || prot == PAGE_EXECUTE_READ) {
205    prot = PAGE_EXECUTE_READWRITE;
206  } else if (prot == PAGE_NOACCESS || prot == PAGE_READONLY) {
207    prot = PAGE_READWRITE;
208  }
209
210  DWORD oldProt;
211  Memory::InvalidateInstructionCache(Addr, Size);
212  return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
213            == TRUE;
214}
215
216bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
217  DWORD prot = getProtection(Addr);
218  if (!prot)
219    return false;
220
221  if (prot == PAGE_NOACCESS) {
222    prot = PAGE_EXECUTE;
223  } else if (prot == PAGE_READONLY) {
224    prot = PAGE_EXECUTE_READ;
225  } else if (prot == PAGE_READWRITE) {
226    prot = PAGE_EXECUTE_READWRITE;
227  }
228
229  DWORD oldProt;
230  Memory::InvalidateInstructionCache(Addr, Size);
231  return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
232            == TRUE;
233}
234
235} // namespace sys
236} // namespace llvm
237