1/*
2 * Copyright (C) 2010 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef OSAllocator_h
27#define OSAllocator_h
28
29#include <algorithm>
30#include <wtf/UnusedParam.h>
31#include <wtf/VMTags.h>
32
33namespace WTF {
34
35class OSAllocator {
36public:
37 enum Usage {
38 UnknownUsage = -1,
39 FastMallocPages = VM_TAG_FOR_TCMALLOC_MEMORY,
40 JSGCHeapPages = VM_TAG_FOR_COLLECTOR_MEMORY,
41 JSVMStackPages = VM_TAG_FOR_REGISTERFILE_MEMORY,
42 JSJITCodePages = VM_TAG_FOR_EXECUTABLEALLOCATOR_MEMORY,
43 };
44
45 // These methods are symmetric; reserveUncommitted allocates VM in an uncommitted state,
46 // releaseDecommitted should be called on a region of VM allocated by a single reservation,
47 // the memory must all currently be in a decommitted state.
48 static void* reserveUncommitted(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false);
49 WTF_EXPORT_PRIVATE static void releaseDecommitted(void*, size_t);
50
51 // These methods are symmetric; they commit or decommit a region of VM (uncommitted VM should
52 // never be accessed, since the OS may not have attached physical memory for these regions).
53 // Clients should only call commit on uncommitted regions and decommit on committed regions.
54 static void commit(void*, size_t, bool writable, bool executable);
55 static void decommit(void*, size_t);
56
57 // These methods are symmetric; reserveAndCommit allocates VM in an committed state,
58 // decommitAndRelease should be called on a region of VM allocated by a single reservation,
59 // the memory must all currently be in a committed state.
60 WTF_EXPORT_PRIVATE static void* reserveAndCommit(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false, bool includesGuardPages = false);
61 static void decommitAndRelease(void* base, size_t size);
62
63 // These methods are akin to reserveAndCommit/decommitAndRelease, above - however rather than
64 // committing/decommitting the entire region additional parameters allow a subregion to be
65 // specified.
66 static void* reserveAndCommit(size_t reserveSize, size_t commitSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
67 static void decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize);
68
69 // Reallocate an existing, committed allocation.
70 // The prior allocation must be fully comitted, and the new size will also be fully committed.
71 // This interface is provided since it may be possible to optimize this operation on some platforms.
72 template<typename T>
73 static T* reallocateCommitted(T*, size_t oldSize, size_t newSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
74
75 static bool canAllocateExecutableMemory();
76
77#if defined(Q_OS_INTEGRITY)
78 static void setMemoryAttributes(void* addr, size_t size, bool writable, bool executable);
79#endif
80};
81
82inline void* OSAllocator::reserveAndCommit(size_t reserveSize, size_t commitSize, Usage usage, bool writable, bool executable)
83{
84 void* base = reserveUncommitted(reserveSize, usage, writable, executable);
85 commit(base, commitSize, writable, executable);
86 return base;
87}
88
89inline void OSAllocator::decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize)
90{
91 ASSERT(decommitBase >= releaseBase && (static_cast<char*>(decommitBase) + decommitSize) <= (static_cast<char*>(releaseBase) + releaseSize));
92#if OS(WINCE)
93 // On most platforms we can actually skip this final decommit; releasing the VM will
94 // implicitly decommit any physical memory in the region. This is not true on WINCE.
95 decommit(decommitBase, decommitSize);
96#else
97 UNUSED_PARAM(decommitBase);
98 UNUSED_PARAM(decommitSize);
99#endif
100 releaseDecommitted(releaseBase, releaseSize);
101}
102
103inline void OSAllocator::decommitAndRelease(void* base, size_t size)
104{
105 decommitAndRelease(releaseBase: base, releaseSize: size, decommitBase: base, decommitSize: size);
106}
107
108template<typename T>
109inline T* OSAllocator::reallocateCommitted(T* oldBase, size_t oldSize, size_t newSize, Usage usage, bool writable, bool executable)
110{
111 void* newBase = reserveAndCommit(newSize, usage, writable, executable);
112 memcpy(newBase, oldBase, std::min(a: oldSize, b: newSize));
113 decommitAndRelease(oldBase, oldSize);
114 return static_cast<T*>(newBase);
115}
116
117} // namespace WTF
118
119using WTF::OSAllocator;
120
121#endif // OSAllocator_h
122

source code of qtdeclarative/src/3rdparty/masm/wtf/OSAllocator.h