JavaScriptCore-903.tar.gz

[apple/javascriptcore.git] / wtf / PageAllocationAligned.cpp

diff --git a/wtf/PageAllocationAligned.cpp b/wtf/PageAllocationAligned.cpp
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+/*
+ * Copyright (C) 2010 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "PageAllocationAligned.h"
+
+namespace WTF {
+
+PageAllocationAligned PageAllocationAligned::allocate(size_t size, size_t alignment, OSAllocator::Usage usage, bool writable, bool executable)
+{
+    ASSERT(isPageAligned(size));
+    ASSERT(isPageAligned(alignment));
+    ASSERT(isPowerOfTwo(alignment));
+    ASSERT(size >= alignment);
+    size_t alignmentMask = alignment - 1;
+
+#if OS(DARWIN)
+    int flags = VM_FLAGS_ANYWHERE;
+    if (usage != OSAllocator::UnknownUsage)
+        flags |= usage;
+    int protection = PROT_READ;
+    if (writable)
+        protection |= PROT_WRITE;
+    if (executable)
+        protection |= PROT_EXEC;
+
+    vm_address_t address = 0;
+    vm_map(current_task(), &address, size, alignmentMask, flags, MEMORY_OBJECT_NULL, 0, FALSE, protection, PROT_READ | PROT_WRITE | PROT_EXEC, VM_INHERIT_DEFAULT);
+    return PageAllocationAligned(reinterpret_cast<void*>(address), size);
+#else
+    size_t alignmentDelta = alignment - pageSize();
+
+    // Resererve with suffcient additional VM to correctly align.
+    size_t reservationSize = size + alignmentDelta;
+    void* reservationBase = OSAllocator::reserveUncommitted(reservationSize, usage, writable, executable);
+
+    // Select an aligned region within the reservation and commit.
+    void* alignedBase = reinterpret_cast<uintptr_t>(reservationBase) & alignmentMask
+        ? reinterpret_cast<void*>((reinterpret_cast<uintptr_t>(reservationBase) & ~alignmentMask) + alignment)
+        : reservationBase;
+    OSAllocator::commit(alignedBase, size, writable, executable);
+
+    return PageAllocationAligned(alignedBase, size, reservationBase, reservationSize);
+#endif
+}
+
+void PageAllocationAligned::deallocate()
+{
+    // Clear base & size before calling release; if this is *inside* allocation
+    // then we won't be able to clear then after deallocating the memory.
+    PageAllocationAligned tmp;
+    std::swap(tmp, *this);
+
+    ASSERT(tmp);
+    ASSERT(!*this);
+
+#if OS(DARWIN)
+    vm_deallocate(current_task(), reinterpret_cast<vm_address_t>(tmp.base()), tmp.size());
+#else
+    ASSERT(tmp.m_reservation.contains(tmp.base(), tmp.size()));
+    OSAllocator::decommitAndRelease(tmp.m_reservation.base(), tmp.m_reservation.size(), tmp.base(), tmp.size());
+#endif
+}
+
+} // namespace WTF