Move Partition Allocator into Chromium base.

third_party/WebKit/Source/wtf/allocator/PageAllocator.h

-/*
- * Copyright (C) 2013 Google 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:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * 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.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
- * OWNER OR 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.
- */
-
-#ifndef WTF_PageAllocator_h
-#define WTF_PageAllocator_h
-
-#include "wtf/Assertions.h"
-#include "wtf/CPU.h"
-#include "wtf/WTFExport.h"
-#include <cstddef>
-#include <stdint.h>
-
-namespace WTF {
-
-#if OS(WIN)
-static const size_t kPageAllocationGranularityShift = 16;  // 64KB
-#else
-static const size_t kPageAllocationGranularityShift = 12;  // 4KB
-#endif
-static const size_t kPageAllocationGranularity =
-    1 << kPageAllocationGranularityShift;
-static const size_t kPageAllocationGranularityOffsetMask =
-    kPageAllocationGranularity - 1;
-static const size_t kPageAllocationGranularityBaseMask =
-    ~kPageAllocationGranularityOffsetMask;
-
-// All Blink-supported systems have 4096 sized system pages and can handle
-// permissions and commit / decommit at this granularity.
-static const size_t kSystemPageSize = 4096;
-static const size_t kSystemPageOffsetMask = kSystemPageSize - 1;
-static const size_t kSystemPageBaseMask = ~kSystemPageOffsetMask;
-
-enum PageAccessibilityConfiguration {
-  PageAccessible,
-  PageInaccessible,
-};
-
-// Allocate one or more pages.
-// The requested address is just a hint; the actual address returned may
-// differ. The returned address will be aligned at least to align bytes.
-// len is in bytes, and must be a multiple of kPageAllocationGranularity.
-// align is in bytes, and must be a power-of-two multiple of
-// kPageAllocationGranularity.
-// If addr is null, then a suitable and randomized address will be chosen
-// automatically.
-// PageAccessibilityConfiguration controls the permission of the
-// allocated pages.
-// This call will return null if the allocation cannot be satisfied.
-WTF_EXPORT void* allocPages(void* addr,
-                            size_t len,
-                            size_t align,
-                            PageAccessibilityConfiguration);
-
-// Free one or more pages.
-// addr and len must match a previous call to allocPages().
-WTF_EXPORT void freePages(void* addr, size_t len);
-
-// Mark one or more system pages as being inaccessible.
-// Subsequently accessing any address in the range will fault, and the
-// addresses will not be re-used by future allocations.
-// len must be a multiple of kSystemPageSize bytes.
-WTF_EXPORT void setSystemPagesInaccessible(void* addr, size_t len);
-
-// Mark one or more system pages as being accessible.
-// The pages will be readable and writeable.
-// len must be a multiple of kSystemPageSize bytes.
-// The result bool value indicates whether the permission
-// change succeeded or not. You must check the result
-// (in most cases you need to RELEASE_ASSERT that it is
-// true).
-WTF_EXPORT WARN_UNUSED_RETURN bool setSystemPagesAccessible(void* addr,
-                                                            size_t len);
-
-// Decommit one or more system pages. Decommitted means that the physical memory
-// is released to the system, but the virtual address space remains reserved.
-// System pages are re-committed by calling recommitSystemPages(). Touching
-// a decommitted page _may_ fault.
-// Clients should not make any assumptions about the contents of decommitted
-// system pages, before or after they write to the page. The only guarantee
-// provided is that the contents of the system page will be deterministic again
-// after recommitting and writing to it. In particlar note that system pages are
-// not guaranteed to be zero-filled upon re-commit. len must be a multiple of
-// kSystemPageSize bytes.
-WTF_EXPORT void decommitSystemPages(void* addr, size_t len);
-
-// Recommit one or more system pages. Decommitted system pages must be
-// recommitted before they are read are written again.
-// Note that this operation may be a no-op on some platforms.
-// len must be a multiple of kSystemPageSize bytes.
-WTF_EXPORT void recommitSystemPages(void* addr, size_t len);
-
-// Discard one or more system pages. Discarding is a hint to the system that
-// the page is no longer required. The hint may:
-// - Do nothing.
-// - Discard the page immediately, freeing up physical pages.
-// - Discard the page at some time in the future in response to memory pressure.
-// Only committed pages should be discarded. Discarding a page does not
-// decommit it, and it is valid to discard an already-discarded page.
-// A read or write to a discarded page will not fault.
-// Reading from a discarded page may return the original page content, or a
-// page full of zeroes.
-// Writing to a discarded page is the only guaranteed way to tell the system
-// that the page is required again. Once written to, the content of the page is
-// guaranteed stable once more. After being written to, the page content may be
-// based on the original page content, or a page of zeroes.
-// len must be a multiple of kSystemPageSize bytes.
-WTF_EXPORT void discardSystemPages(void* addr, size_t len);
-
-WTF_EXPORT ALWAYS_INLINE uintptr_t roundUpToSystemPage(uintptr_t address) {
-  return (address + kSystemPageOffsetMask) & kSystemPageBaseMask;
-}
-
-WTF_EXPORT ALWAYS_INLINE uintptr_t roundDownToSystemPage(uintptr_t address) {
-  return address & kSystemPageBaseMask;
-}
-
-// Only allowed inside WTF for investigating WTF::initializeWithoutV8 crashes.
-// Guess, the function fails because of mmap (or VirtualAlloc) failure.
-// The following function returns errno (or GetLastError code) when mmap
-// (or VirtualAlloc) fails.
-uint32_t getAllocPageErrorCode();
-
-}  // namespace WTF
-
-#endif  // WTF_PageAllocator_h