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#pragma once
27
28#include <algorithm>
29#include <wtf/VMTags.h>
30
31namespace WTF {
32
33class OSAllocator {
34public:
35 enum Usage {
36 UnknownUsage = -1,
37 FastMallocPages = VM_TAG_FOR_TCMALLOC_MEMORY,
38 JSVMStackPages = VM_TAG_FOR_REGISTERFILE_MEMORY,
39 JSJITCodePages = VM_TAG_FOR_EXECUTABLEALLOCATOR_MEMORY,
40 };
41
42 // These methods are symmetric; reserveUncommitted allocates VM in an uncommitted state,
43 // releaseDecommitted should be called on a region of VM allocated by a single reservation,
44 // the memory must all currently be in a decommitted state. reserveUncommitted returns to
45 // you memory that is zeroed.
46 WTF_EXPORT_PRIVATE static void* reserveUncommitted(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false, bool includesGuardPages = false);
47 WTF_EXPORT_PRIVATE static void releaseDecommitted(void*, size_t);
48
49 // These methods are symmetric; they commit or decommit a region of VM (uncommitted VM should
50 // never be accessed, since the OS may not have attached physical memory for these regions).
51 // Clients should only call commit on uncommitted regions and decommit on committed regions.
52 WTF_EXPORT_PRIVATE static void commit(void*, size_t, bool writable, bool executable);
53 WTF_EXPORT_PRIVATE static void decommit(void*, size_t);
54
55 // These methods are symmetric; reserveAndCommit allocates VM in an committed state,
56 // decommitAndRelease should be called on a region of VM allocated by a single reservation,
57 // the memory must all currently be in a committed state.
58 WTF_EXPORT_PRIVATE static void* reserveAndCommit(size_t, Usage = UnknownUsage, bool writable = true, bool executable = false, bool includesGuardPages = false);
59 static void decommitAndRelease(void* base, size_t size);
60
61 // These methods are akin to reserveAndCommit/decommitAndRelease, above - however rather than
62 // committing/decommitting the entire region additional parameters allow a subregion to be
63 // specified.
64 WTF_EXPORT_PRIVATE static void* reserveAndCommit(size_t reserveSize, size_t commitSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
65
66 // Reallocate an existing, committed allocation.
67 // The prior allocation must be fully comitted, and the new size will also be fully committed.
68 // This interface is provided since it may be possible to optimize this operation on some platforms.
69 template<typename T>
70 static T* reallocateCommitted(T*, size_t oldSize, size_t newSize, Usage = UnknownUsage, bool writable = true, bool executable = false);
71
72 // Hint to the OS that an address range is not expected to be accessed anytime soon.
73 WTF_EXPORT_PRIVATE static void hintMemoryNotNeededSoon(void*, size_t);
74};
75
76inline void* OSAllocator::reserveAndCommit(size_t reserveSize, size_t commitSize, Usage usage, bool writable, bool executable)
77{
78 void* base = reserveUncommitted(reserveSize, usage, writable, executable);
79 commit(base, commitSize, writable, executable);
80 return base;
81}
82
83inline void OSAllocator::decommitAndRelease(void* releaseBase, size_t releaseSize)
84{
85 releaseDecommitted(releaseBase, releaseSize);
86}
87
88template<typename T>
89inline T* OSAllocator::reallocateCommitted(T* oldBase, size_t oldSize, size_t newSize, Usage usage, bool writable, bool executable)
90{
91 void* newBase = reserveAndCommit(newSize, usage, writable, executable);
92 memcpy(newBase, oldBase, std::min(oldSize, newSize));
93 decommitAndRelease(oldBase, oldSize);
94 return static_cast<T*>(newBase);
95}
96
97} // namespace WTF
98
99using WTF::OSAllocator;
100