99 lines
3.8 KiB
C++
99 lines
3.8 KiB
C++
/*
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* Copyright (C) 2010 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <wtf/StdLibExtras.h>
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namespace WTF {
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// We attempt to guess a value that is *AT LEAST* as large as the system's actual page size.
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// This is impossible to do correctly at build time, but JSC really needs it at build time, so
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// we have a RELEASE_ASSERT() inside WTF::pageSize to make sure it is set properly at runtime.
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// All of these values are going to be incorrect on systems configured to use larger than normal
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// page size, so on such systems it is expected that WebKit will crash until this value is changed
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// and recompiled. Sorry.
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//
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// macOS x86_64 uses 4 KiB, but Apple's aarch64 systems use 16 KiB. Use 16 KiB on all Apple systems
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// for consistency.
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//
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// Most Linux and Windows systems use a page size of 4 KiB.
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//
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// On Linux, Power systems normally use 64 KiB pages.
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//
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// Use 64 KiB for any unknown CPUs to be conservative.
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#if OS(DARWIN) || PLATFORM(PLAYSTATION) || CPU(MIPS) || CPU(MIPS64)
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constexpr size_t CeilingOnPageSize = 16 * KB;
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#elif CPU(PPC) || CPU(PPC64) || CPU(PPC64LE) || CPU(UNKNOWN)
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constexpr size_t CeilingOnPageSize = 64 * KB;
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#elif OS(WINDOWS) || CPU(X86) || CPU(X86_64) || CPU(ARM) || CPU(ARM64) || CPU(RISCV64)
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constexpr size_t CeilingOnPageSize = 4 * KB;
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#else
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#error Must set CeilingOnPageSize in PageBlock.h when adding a new CPU architecture!
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#endif
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WTF_EXPORT_PRIVATE size_t pageSize();
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WTF_EXPORT_PRIVATE size_t pageMask();
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inline bool isPageAligned(void* address) { return !(reinterpret_cast<intptr_t>(address) & (pageSize() - 1)); }
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inline bool isPageAligned(size_t size) { return !(size & (pageSize() - 1)); }
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inline bool isPowerOfTwo(size_t size) { return !(size & (size - 1)); }
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class PageBlock {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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PageBlock() = default;
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PageBlock(void*, size_t, bool hasGuardPages);
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void* base() const { return m_base; }
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size_t size() const { return m_size; }
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operator bool() const { return !!m_realBase; }
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bool contains(void* containedBase, size_t containedSize)
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{
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return containedBase >= m_base
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&& (static_cast<char*>(containedBase) + containedSize) <= (static_cast<char*>(m_base) + m_size);
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}
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private:
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void* m_realBase { nullptr };
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void* m_base { nullptr };
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size_t m_size { 0 };
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};
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inline PageBlock::PageBlock(void* base, size_t size, bool hasGuardPages)
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: m_realBase(base)
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, m_base(static_cast<char*>(base) + ((base && hasGuardPages) ? pageSize() : 0))
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, m_size(size)
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{
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}
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} // namespace WTF
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using WTF::CeilingOnPageSize;
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using WTF::pageSize;
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using WTF::isPageAligned;
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using WTF::isPowerOfTwo;
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