michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  *
michael@0:  * ***** BEGIN LICENSE BLOCK *****
michael@0:  * Copyright (C) 2010 Apple Inc. All rights reserved.
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
michael@0:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
michael@0:  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
michael@0:  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
michael@0:  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
michael@0:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
michael@0:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
michael@0:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
michael@0:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
michael@0:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
michael@0:  * THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  *
michael@0:  * ***** END LICENSE BLOCK ***** */
michael@0: 
michael@0: #include "assembler/wtf/Platform.h"
michael@0: 
michael@0: #if WTF_OS_UNIX && !WTF_OS_SYMBIAN
michael@0: 
michael@0: #include "yarr/OSAllocator.h"
michael@0: 
michael@0: #include <errno.h>
michael@0: #include <sys/mman.h>
michael@0: #include "assembler/wtf/Assertions.h"
michael@0: 
michael@0: namespace WTF {
michael@0: 
michael@0: void* OSAllocator::reserveUncommitted(size_t bytes, Usage usage, bool writable, bool executable)
michael@0: {
michael@0:     void* result = reserveAndCommit(bytes, usage, writable, executable);
michael@0: #if HAVE_MADV_FREE_REUSE
michael@0:     // To support the "reserve then commit" model, we have to initially decommit.
michael@0:     while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
michael@0: #endif
michael@0:     return result;
michael@0: }
michael@0: 
michael@0: void* OSAllocator::reserveAndCommit(size_t bytes, Usage usage, bool writable, bool executable)
michael@0: {
michael@0:     // All POSIX reservations start out logically committed.
michael@0:     int protection = PROT_READ;
michael@0:     if (writable)
michael@0:         protection |= PROT_WRITE;
michael@0:     if (executable)
michael@0:         protection |= PROT_EXEC;
michael@0: 
michael@0:     int flags = MAP_PRIVATE | MAP_ANON;
michael@0: 
michael@0: #if WTF_OS_DARWIN && !defined(BUILDING_ON_TIGER)
michael@0:     int fd = usage;
michael@0: #else
michael@0:     int fd = -1;
michael@0: #endif
michael@0: 
michael@0:     void* result = 0;
michael@0: #if (WTF_OS_DARWIN && WTF_CPU_X86_64)
michael@0:     if (executable) {
michael@0:         // Cook up an address to allocate at, using the following recipe:
michael@0:         //   17 bits of zero, stay in userspace kids.
michael@0:         //   26 bits of randomness for ASLR.
michael@0:         //   21 bits of zero, at least stay aligned within one level of the pagetables.
michael@0:         //
michael@0:         // But! - as a temporary workaround for some plugin problems (rdar://problem/6812854),
michael@0:         // for now instead of 2^26 bits of ASLR lets stick with 25 bits of randomization plus
michael@0:         // 2^24, which should put up somewhere in the middle of userspace (in the address range
michael@0:         // 0x200000000000 .. 0x5fffffffffff).
michael@0:         intptr_t randomLocation = 0;
michael@0:         randomLocation = arc4random() & ((1 << 25) - 1);
michael@0:         randomLocation += (1 << 24);
michael@0:         randomLocation <<= 21;
michael@0:         result = reinterpret_cast<void*>(randomLocation);
michael@0:     }
michael@0: #endif
michael@0: 
michael@0:     result = mmap(result, bytes, protection, flags, fd, 0);
michael@0:     if (result == MAP_FAILED)
michael@0:         CRASH();
michael@0:     return result;
michael@0: }
michael@0: 
michael@0: void OSAllocator::commit(void* address, size_t bytes, bool, bool)
michael@0: {
michael@0: #if HAVE_MADV_FREE_REUSE
michael@0:     while (madvise(address, bytes, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { }
michael@0: #else
michael@0:     // Non-MADV_FREE_REUSE reservations automatically commit on demand.
michael@0:     UNUSED_PARAM(address);
michael@0:     UNUSED_PARAM(bytes);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: void OSAllocator::decommit(void* address, size_t bytes)
michael@0: {
michael@0: #if HAVE_MADV_FREE_REUSE
michael@0:     while (madvise(address, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
michael@0: #elif HAVE_MADV_FREE
michael@0:     while (madvise(address, bytes, MADV_FREE) == -1 && errno == EAGAIN) { }
michael@0: #elif HAVE_MADV_DONTNEED
michael@0:     while (madvise(address, bytes, MADV_DONTNEED) == -1 && errno == EAGAIN) { }
michael@0: #else
michael@0:     UNUSED_PARAM(address);
michael@0:     UNUSED_PARAM(bytes);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: void OSAllocator::releaseDecommitted(void* address, size_t bytes)
michael@0: {
michael@0:     int result = munmap(address, bytes);
michael@0:     if (result == -1)
michael@0:         CRASH();
michael@0: }
michael@0: 
michael@0: } // namespace WTF
michael@0: 
michael@0: #endif