| /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
| * vim: set ts=8 sts=4 et sw=4 tw=99: |
| * |
| * ***** BEGIN LICENSE BLOCK ***** |
| * 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. |
| * |
| * ***** END LICENSE BLOCK ***** */ |
| |
| #include "assembler/wtf/Platform.h" |
| |
| #if WTF_OS_UNIX && !WTF_OS_SYMBIAN |
| |
| #include "OSAllocator.h" |
| |
| #include <errno.h> |
| #include <sys/mman.h> |
| #include "wtf/Assertions.h" |
| |
| namespace WTF { |
| |
| void* OSAllocator::reserveUncommitted(size_t bytes, Usage usage, bool writable, bool executable) |
| { |
| void* result = reserveAndCommit(bytes, usage, writable, executable); |
| #if HAVE_MADV_FREE_REUSE |
| // To support the "reserve then commit" model, we have to initially decommit. |
| while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { } |
| #endif |
| return result; |
| } |
| |
| void* OSAllocator::reserveAndCommit(size_t bytes, Usage usage, bool writable, bool executable) |
| { |
| // All POSIX reservations start out logically committed. |
| int protection = PROT_READ; |
| if (writable) |
| protection |= PROT_WRITE; |
| if (executable) |
| protection |= PROT_EXEC; |
| |
| int flags = MAP_PRIVATE | MAP_ANON; |
| |
| #if WTF_OS_DARWIN && !defined(BUILDING_ON_TIGER) |
| int fd = usage; |
| #else |
| int fd = -1; |
| #endif |
| |
| void* result = 0; |
| #if (WTF_OS_DARWIN && WTF_CPU_X86_64) |
| if (executable) { |
| // Cook up an address to allocate at, using the following recipe: |
| // 17 bits of zero, stay in userspace kids. |
| // 26 bits of randomness for ASLR. |
| // 21 bits of zero, at least stay aligned within one level of the pagetables. |
| // |
| // But! - as a temporary workaround for some plugin problems (rdar://problem/6812854), |
| // for now instead of 2^26 bits of ASLR lets stick with 25 bits of randomization plus |
| // 2^24, which should put up somewhere in the middle of userspace (in the address range |
| // 0x200000000000 .. 0x5fffffffffff). |
| intptr_t randomLocation = 0; |
| randomLocation = arc4random() & ((1 << 25) - 1); |
| randomLocation += (1 << 24); |
| randomLocation <<= 21; |
| result = reinterpret_cast<void*>(randomLocation); |
| } |
| #endif |
| |
| result = mmap(result, bytes, protection, flags, fd, 0); |
| if (result == MAP_FAILED) |
| CRASH(); |
| return result; |
| } |
| |
| void OSAllocator::commit(void* address, size_t bytes, bool, bool) |
| { |
| #if HAVE_MADV_FREE_REUSE |
| while (madvise(address, bytes, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { } |
| #else |
| // Non-MADV_FREE_REUSE reservations automatically commit on demand. |
| UNUSED_PARAM(address); |
| UNUSED_PARAM(bytes); |
| #endif |
| } |
| |
| void OSAllocator::decommit(void* address, size_t bytes) |
| { |
| #if HAVE_MADV_FREE_REUSE |
| while (madvise(address, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { } |
| #elif HAVE_MADV_FREE |
| while (madvise(address, bytes, MADV_FREE) == -1 && errno == EAGAIN) { } |
| #elif HAVE_MADV_DONTNEED |
| while (madvise(address, bytes, MADV_DONTNEED) == -1 && errno == EAGAIN) { } |
| #else |
| UNUSED_PARAM(address); |
| UNUSED_PARAM(bytes); |
| #endif |
| } |
| |
| void OSAllocator::releaseDecommitted(void* address, size_t bytes) |
| { |
| int result = munmap(address, bytes); |
| if (result == -1) |
| CRASH(); |
| } |
| |
| } // namespace WTF |
| |
| #endif |