1 //===- Win32/Memory.cpp - Win32 Memory Implementation -----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file provides the Win32 specific implementation of various Memory
11 // management utilities
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Support/DataTypes.h"
16 #include "llvm/Support/ErrorHandling.h"
17 #include "llvm/Support/Process.h"
18 #include "llvm/Support/WindowsError.h"
20 // The Windows.h header must be the last one included.
21 #include "WindowsSupport.h"
25 DWORD getWindowsProtectionFlags(unsigned 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:
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:
45 llvm_unreachable("Illegal memory protection flag specified!");
47 // Provide a default return value as required by some compilers.
51 size_t getAllocationGranularity() {
53 ::GetSystemInfo(&Info);
54 if (Info.dwPageSize > Info.dwAllocationGranularity)
55 return Info.dwPageSize;
57 return Info.dwAllocationGranularity;
65 //===----------------------------------------------------------------------===//
66 //=== WARNING: Implementation here must contain only Win32 specific code
67 //=== and must not be UNIX code
68 //===----------------------------------------------------------------------===//
70 MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
71 const MemoryBlock *const NearBlock,
73 std::error_code &EC) {
74 EC = std::error_code();
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 // Avoid using one-time initialization of static locals here, since they
82 // aren't thread safe with MSVC.
83 static volatile size_t GranularityCached;
84 size_t Granularity = GranularityCached;
85 if (Granularity == 0) {
86 Granularity = getAllocationGranularity();
87 GranularityCached = Granularity;
90 const size_t NumBlocks = (NumBytes+Granularity-1)/Granularity;
92 uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
96 // If the requested address is not aligned to the allocation granularity,
97 // round up to get beyond NearBlock. VirtualAlloc would have rounded down.
98 if (Start && Start % Granularity != 0)
99 Start += Granularity - Start % Granularity;
101 DWORD Protect = getWindowsProtectionFlags(Flags);
103 void *PA = ::VirtualAlloc(reinterpret_cast<void*>(Start),
104 NumBlocks*Granularity,
105 MEM_RESERVE | MEM_COMMIT, Protect);
108 // Try again without the NearBlock hint
109 return allocateMappedMemory(NumBytes, NULL, Flags, EC);
111 EC = mapWindowsError(::GetLastError());
112 return MemoryBlock();
117 Result.Size = NumBlocks*Granularity;
120 Memory::InvalidateInstructionCache(Result.Address, Result.Size);
125 std::error_code Memory::releaseMappedMemory(MemoryBlock &M) {
126 if (M.Address == 0 || M.Size == 0)
127 return std::error_code();
129 if (!VirtualFree(M.Address, 0, MEM_RELEASE))
130 return mapWindowsError(::GetLastError());
135 return std::error_code();
138 std::error_code Memory::protectMappedMemory(const MemoryBlock &M,
140 if (M.Address == 0 || M.Size == 0)
141 return std::error_code();
143 DWORD Protect = getWindowsProtectionFlags(Flags);
146 if (!VirtualProtect(M.Address, M.Size, Protect, &OldFlags))
147 return mapWindowsError(::GetLastError());
150 Memory::InvalidateInstructionCache(M.Address, M.Size);
152 return std::error_code();
155 /// InvalidateInstructionCache - Before the JIT can run a block of code
156 /// that has been emitted it must invalidate the instruction cache on some
158 void Memory::InvalidateInstructionCache(
159 const void *Addr, size_t Len) {
160 FlushInstructionCache(GetCurrentProcess(), Addr, Len);
164 MemoryBlock Memory::AllocateRWX(size_t NumBytes,
165 const MemoryBlock *NearBlock,
166 std::string *ErrMsg) {
169 MB = allocateMappedMemory(NumBytes, NearBlock,
170 MF_READ|MF_WRITE|MF_EXEC, EC);
171 if (EC != std::error_code() && ErrMsg) {
172 MakeErrMsg(ErrMsg, EC.message());
177 bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
178 std::error_code EC = releaseMappedMemory(M);
179 if (EC == std::error_code())
181 MakeErrMsg(ErrMsg, EC.message());
185 static DWORD getProtection(const void *addr) {
186 MEMORY_BASIC_INFORMATION info;
187 if (sizeof(info) == ::VirtualQuery(addr, &info, sizeof(info))) {
193 bool Memory::setWritable(MemoryBlock &M, std::string *ErrMsg) {
194 if (!setRangeWritable(M.Address, M.Size)) {
195 return MakeErrMsg(ErrMsg, "Cannot set memory to writeable");
200 bool Memory::setExecutable(MemoryBlock &M, std::string *ErrMsg) {
201 if (!setRangeExecutable(M.Address, M.Size)) {
202 return MakeErrMsg(ErrMsg, "Cannot set memory to executable");
207 bool Memory::setRangeWritable(const void *Addr, size_t Size) {
208 DWORD prot = getProtection(Addr);
212 if (prot == PAGE_EXECUTE || prot == PAGE_EXECUTE_READ) {
213 prot = PAGE_EXECUTE_READWRITE;
214 } else if (prot == PAGE_NOACCESS || prot == PAGE_READONLY) {
215 prot = PAGE_READWRITE;
219 Memory::InvalidateInstructionCache(Addr, Size);
220 return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)
224 bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
225 DWORD prot = getProtection(Addr);
229 if (prot == PAGE_NOACCESS) {
231 } else if (prot == PAGE_READONLY) {
232 prot = PAGE_EXECUTE_READ;
233 } else if (prot == PAGE_READWRITE) {
234 prot = PAGE_EXECUTE_READWRITE;
238 Memory::InvalidateInstructionCache(Addr, Size);
239 return ::VirtualProtect(const_cast<LPVOID>(Addr), Size, prot, &oldProt)