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 <wtf/UnusedParam.h>
30 #include <wtf/VMTags.h>
31 #include <wtf/VMTags.h>
32
33 namespace WTF {
34
35 class OSAllocator {
36 public:
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 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 static void* reserveAndCommit(size_t, Usage = UnknownUsage, bool writable = true, bool executable = 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
reserveAndCommit(size_t reserveSize,size_t commitSize,Usage usage,bool writable,bool executable)70 inline void* OSAllocator::reserveAndCommit(size_t reserveSize, size_t commitSize, Usage usage, bool writable, bool executable)
71 {
72 void* base = reserveUncommitted(reserveSize, usage, writable, executable);
73 commit(base, commitSize, writable, executable);
74 return base;
75 }
76
decommitAndRelease(void * releaseBase,size_t releaseSize,void * decommitBase,size_t decommitSize)77 inline void OSAllocator::decommitAndRelease(void* releaseBase, size_t releaseSize, void* decommitBase, size_t decommitSize)
78 {
79 ASSERT(decommitBase >= releaseBase && (static_cast<char*>(decommitBase) + decommitSize) <= (static_cast<char*>(releaseBase) + releaseSize));
80 #if OS(WINCE) || OS(SYMBIAN)
81 // On most platforms we can actually skip this final decommit; releasing the VM will
82 // implicitly decommit any physical memory in the region. This is not true on WINCE.
83 // On Symbian, this makes implementation simpler and better aligned with the RChunk API
84 decommit(decommitBase, decommitSize);
85 #else
86 UNUSED_PARAM(decommitBase);
87 UNUSED_PARAM(decommitSize);
88 #endif
89 releaseDecommitted(releaseBase, releaseSize);
90 }
91
decommitAndRelease(void * base,size_t size)92 inline void OSAllocator::decommitAndRelease(void* base, size_t size)
93 {
94 decommitAndRelease(base, size, base, size);
95 }
96
97 } // namespace WTF
98
99 using WTF::OSAllocator;
100
101 #endif // OSAllocator_h
102