LCOV - code coverage report
Current view: directory - js/src/yarr - OSAllocatorPosix.cpp (source / functions) Found Hit Coverage
Test: app.info Lines: 25 15 60.0 %
Date: 2012-06-02 Functions: 5 2 40.0 %

       1                 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
       2                 :  * vim: set ts=8 sw=4 et tw=99 ft=cpp:
       3                 :  *
       4                 :  * ***** BEGIN LICENSE BLOCK *****
       5                 :  * Copyright (C) 2010 Apple Inc. All rights reserved.
       6                 :  *
       7                 :  * Redistribution and use in source and binary forms, with or without
       8                 :  * modification, are permitted provided that the following conditions
       9                 :  * are met:
      10                 :  * 1. Redistributions of source code must retain the above copyright
      11                 :  *    notice, this list of conditions and the following disclaimer.
      12                 :  * 2. Redistributions in binary form must reproduce the above copyright
      13                 :  *    notice, this list of conditions and the following disclaimer in the
      14                 :  *    documentation and/or other materials provided with the distribution.
      15                 :  *
      16                 :  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
      17                 :  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
      18                 :  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
      19                 :  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
      20                 :  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
      21                 :  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
      22                 :  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
      23                 :  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
      24                 :  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      25                 :  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
      26                 :  * THE POSSIBILITY OF SUCH DAMAGE.
      27                 :  *
      28                 :  * ***** END LICENSE BLOCK ***** */
      29                 : 
      30                 : #include "assembler/wtf/Platform.h"
      31                 : 
      32                 : #if WTF_OS_UNIX && !WTF_OS_SYMBIAN
      33                 : 
      34                 : #include "OSAllocator.h"
      35                 : 
      36                 : #include <errno.h>
      37                 : #include <sys/mman.h>
      38                 : #include "wtf/Assertions.h"
      39                 : 
      40                 : namespace WTF {
      41                 : 
      42               0 : void* OSAllocator::reserveUncommitted(size_t bytes, Usage usage, bool writable, bool executable)
      43                 : {
      44               0 :     void* result = reserveAndCommit(bytes, usage, writable, executable);
      45                 : #if HAVE_MADV_FREE_REUSE
      46                 :     // To support the "reserve then commit" model, we have to initially decommit.
      47                 :     while (madvise(result, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
      48                 : #endif
      49               0 :     return result;
      50                 : }
      51                 : 
      52           31359 : void* OSAllocator::reserveAndCommit(size_t bytes, Usage usage, bool writable, bool executable)
      53                 : {
      54                 :     // All POSIX reservations start out logically committed.
      55           31359 :     int protection = PROT_READ;
      56           31359 :     if (writable)
      57           31359 :         protection |= PROT_WRITE;
      58           31359 :     if (executable)
      59               0 :         protection |= PROT_EXEC;
      60                 : 
      61           31359 :     int flags = MAP_PRIVATE | MAP_ANON;
      62                 : 
      63                 : #if WTF_OS_DARWIN && !defined(BUILDING_ON_TIGER)
      64                 :     int fd = usage;
      65                 : #else
      66           31359 :     int fd = -1;
      67                 : #endif
      68                 : 
      69           31359 :     void* result = 0;
      70                 : #if (WTF_OS_DARWIN && WTF_CPU_X86_64)
      71                 :     if (executable) {
      72                 :         // Cook up an address to allocate at, using the following recipe:
      73                 :         //   17 bits of zero, stay in userspace kids.
      74                 :         //   26 bits of randomness for ASLR.
      75                 :         //   21 bits of zero, at least stay aligned within one level of the pagetables.
      76                 :         //
      77                 :         // But! - as a temporary workaround for some plugin problems (rdar://problem/6812854),
      78                 :         // for now instead of 2^26 bits of ASLR lets stick with 25 bits of randomization plus
      79                 :         // 2^24, which should put up somewhere in the middle of userspace (in the address range
      80                 :         // 0x200000000000 .. 0x5fffffffffff).
      81                 :         intptr_t randomLocation = 0;
      82                 :         randomLocation = arc4random() & ((1 << 25) - 1);
      83                 :         randomLocation += (1 << 24);
      84                 :         randomLocation <<= 21;
      85                 :         result = reinterpret_cast<void*>(randomLocation);
      86                 :     }
      87                 : #endif
      88                 : 
      89           31359 :     result = mmap(result, bytes, protection, flags, fd, 0);
      90           31359 :     if (result == MAP_FAILED)
      91               0 :         CRASH();
      92           31359 :     return result;
      93                 : }
      94                 : 
      95               0 : void OSAllocator::commit(void* address, size_t bytes, bool, bool)
      96                 : {
      97                 : #if HAVE_MADV_FREE_REUSE
      98                 :     while (madvise(address, bytes, MADV_FREE_REUSE) == -1 && errno == EAGAIN) { }
      99                 : #else
     100                 :     // Non-MADV_FREE_REUSE reservations automatically commit on demand.
     101                 :     UNUSED_PARAM(address);
     102                 :     UNUSED_PARAM(bytes);
     103                 : #endif
     104               0 : }
     105                 : 
     106               0 : void OSAllocator::decommit(void* address, size_t bytes)
     107                 : {
     108                 : #if HAVE_MADV_FREE_REUSE
     109                 :     while (madvise(address, bytes, MADV_FREE_REUSABLE) == -1 && errno == EAGAIN) { }
     110                 : #elif HAVE_MADV_FREE
     111                 :     while (madvise(address, bytes, MADV_FREE) == -1 && errno == EAGAIN) { }
     112                 : #elif HAVE_MADV_DONTNEED
     113                 :     while (madvise(address, bytes, MADV_DONTNEED) == -1 && errno == EAGAIN) { }
     114                 : #else
     115                 :     UNUSED_PARAM(address);
     116                 :     UNUSED_PARAM(bytes);
     117                 : #endif
     118               0 : }
     119                 : 
     120           31359 : void OSAllocator::releaseDecommitted(void* address, size_t bytes)
     121                 : {
     122           31359 :     int result = munmap(address, bytes);
     123           31359 :     if (result == -1)
     124               0 :         CRASH();
     125           31359 : }
     126                 : 
     127                 : } // namespace WTF
     128                 : 
     129                 : #endif

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