wtf/PageAllocationAligned.cpp

   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 #include "config.h"
  27 #include "PageAllocationAligned.h"
  28
  29 namespace WTF {
  30
  31 PageAllocationAligned PageAllocationAligned::allocate(size_t size, size_t alignment, OSAllocator::Usage usage, bool writable, bool executable)
  32 {
  33     ASSERT(isPageAligned(size));
  34     ASSERT(isPageAligned(alignment));
  35     ASSERT(isPowerOfTwo(alignment));
  36     ASSERT(size >= alignment);
  37     size_t alignmentMask = alignment - 1;
  38
  39 #if OS(DARWIN)
  40     int flags = VM_FLAGS_ANYWHERE;
  41     if (usage != OSAllocator::UnknownUsage)
  42         flags |= usage;
  43     int protection = PROT_READ;
  44     if (writable)
  45         protection |= PROT_WRITE;
  46     if (executable)
  47         protection |= PROT_EXEC;
  48
  49     vm_address_t address = 0;
  50     vm_map(current_task(), &address, size, alignmentMask, flags, MEMORY_OBJECT_NULL, 0, FALSE, protection, PROT_READ | PROT_WRITE | PROT_EXEC, VM_INHERIT_DEFAULT);
  51     return PageAllocationAligned(reinterpret_cast<void*>(address), size);
  52 #else
  53     size_t alignmentDelta = alignment - pageSize();
  54
  55     // Resererve with suffcient additional VM to correctly align.
  56     size_t reservationSize = size + alignmentDelta;
  57     void* reservationBase = OSAllocator::reserveUncommitted(reservationSize, usage, writable, executable);
  58
  59     // Select an aligned region within the reservation and commit.
  60     void* alignedBase = reinterpret_cast<uintptr_t>(reservationBase) & alignmentMask
  61         ? reinterpret_cast<void*>((reinterpret_cast<uintptr_t>(reservationBase) & ~alignmentMask) + alignment)
  62         : reservationBase;
  63     OSAllocator::commit(alignedBase, size, writable, executable);
  64
  65     return PageAllocationAligned(alignedBase, size, reservationBase, reservationSize);
  66 #endif
  67 }
  68
  69 void PageAllocationAligned::deallocate()
  70 {
  71     // Clear base & size before calling release; if this is *inside* allocation
  72     // then we won't be able to clear then after deallocating the memory.
  73     PageAllocationAligned tmp;
  74     std::swap(tmp, *this);
  75
  76     ASSERT(tmp);
  77     ASSERT(!*this);
  78
  79 #if OS(DARWIN)
  80     vm_deallocate(current_task(), reinterpret_cast<vm_address_t>(tmp.base()), tmp.size());
  81 #else
  82     ASSERT(tmp.m_reservation.contains(tmp.base(), tmp.size()));
  83     OSAllocator::decommitAndRelease(tmp.m_reservation.base(), tmp.m_reservation.size(), tmp.base(), tmp.size());
  84 #endif
  85 }
  86
  87 } // namespace WTF