1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
//===- Win32/Memory.cpp - Win32 Memory Implementation -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides the Win32 specific implementation of various Memory
// management utilities
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/WindowsError.h"
// The Windows.h header must be the last one included.
#include "WindowsSupport.h"
namespace {
DWORD getWindowsProtectionFlags(unsigned Flags) {
switch (Flags) {
// Contrary to what you might expect, the Windows page protection flags
// are not a bitwise combination of RWX values
case llvm::sys::Memory::MF_READ:
return PAGE_READONLY;
case llvm::sys::Memory::MF_WRITE:
// Note: PAGE_WRITE is not supported by VirtualProtect
return PAGE_READWRITE;
case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
return PAGE_READWRITE;
case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
return PAGE_EXECUTE_READ;
case llvm::sys::Memory::MF_READ |
llvm::sys::Memory::MF_WRITE |
llvm::sys::Memory::MF_EXEC:
return PAGE_EXECUTE_READWRITE;
case llvm::sys::Memory::MF_EXEC:
return PAGE_EXECUTE;
default:
llvm_unreachable("Illegal memory protection flag specified!");
}
// Provide a default return value as required by some compilers.
return PAGE_NOACCESS;
}
size_t getAllocationGranularity() {
SYSTEM_INFO Info;
::GetSystemInfo(&Info);
if (Info.dwPageSize > Info.dwAllocationGranularity)
return Info.dwPageSize;
else
return Info.dwAllocationGranularity;
}
} // namespace
namespace llvm {
namespace sys {
//===----------------------------------------------------------------------===//
//=== WARNING: Implementation here must contain only Win32 specific code
//=== and must not be UNIX code
//===----------------------------------------------------------------------===//
MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
const MemoryBlock *const NearBlock,
unsigned Flags,
std::error_code &EC) {
EC = std::error_code();
if (NumBytes == 0)
return MemoryBlock();
// While we'd be happy to allocate single pages, the Windows allocation
// granularity may be larger than a single page (in practice, it is 64K)
// so mapping less than that will create an unreachable fragment of memory.
// Avoid using one-time initialization of static locals here, since they
// aren't thread safe with MSVC.
static volatile size_t GranularityCached;
size_t Granularity = GranularityCached;
if (Granularity == 0) {
Granularity = getAllocationGranularity();
GranularityCached = Granularity;
}
const size_t NumBlocks = (NumBytes+Granularity-1)/Granularity;
uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
NearBlock->size()
: 0;
// If the requested address is not aligned to the allocation granularity,
// round up to get beyond NearBlock. VirtualAlloc would have rounded down.
if (Start && Start % Granularity != 0)
Start += Granularity - Start % Granularity;
DWORD Protect = getWindowsProtectionFlags(Flags);
void *PA = ::VirtualAlloc(reinterpret_cast<void*>(Start),
NumBlocks*Granularity,
MEM_RESERVE | MEM_COMMIT, Protect);
if (PA == NULL) {
if (NearBlock) {
// Try again without the NearBlock hint
return allocateMappedMemory(NumBytes, NULL, Flags, EC);
}
EC = mapWindowsError(::GetLastError());
return MemoryBlock();
}
MemoryBlock Result;
Result.Address = PA;
Result.Size = NumBlocks*Granularity;
if (Flags & MF_EXEC)
Memory::InvalidateInstructionCache(Result.Address, Result.Size);
return Result;
}
std::error_code Memory::releaseMappedMemory(MemoryBlock &M) {
if (M.Address == 0 || M.Size == 0)
return std::error_code();
if (!VirtualFree(M.Address, 0, MEM_RELEASE))
return mapWindowsError(::GetLastError());
M.Address = 0;
M.Size = 0;
return std::error_code();
}
std::error_code Memory::protectMappedMemory(const MemoryBlock &M,
unsigned Flags) {
if (M.Address == 0 || M.Size == 0)
return std::error_code();
DWORD Protect = getWindowsProtectionFlags(Flags);
DWORD OldFlags;
if (!VirtualProtect(M.Address, M.Size, Protect, &OldFlags))
return mapWindowsError(::GetLastError());
if (Flags & MF_EXEC)
Memory::InvalidateInstructionCache(M.Address, M.Size);
return std::error_code();
}
/// InvalidateInstructionCache - Before the JIT can run a block of code
/// that has been emitted it must invalidate the instruction cache on some
/// platforms.
void Memory::InvalidateInstructionCache(
const void *Addr, size_t Len) {
FlushInstructionCache(GetCurrentProcess(), Addr, Len);
}
} // namespace sys
} // namespace llvm
|
