jit/ExecutableAllocatorPosix.cpp

   1 /*
   2  * Copyright (C) 2008 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. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27
  28 #include "ExecutableAllocator.h"
  29
  30 #if ENABLE(ASSEMBLER) && OS(UNIX) && !OS(SYMBIAN)
  31
  32 #include <sys/mman.h>
  33 #include <unistd.h>
  34 #include <wtf/VMTags.h>
  35
  36 namespace JSC {
  37
  38 #if !(OS(DARWIN) && CPU(X86_64))
  39
  40 void ExecutableAllocator::intializePageSize()
  41 {
  42     ExecutableAllocator::pageSize = getpagesize();
  43 }
  44
  45 ExecutablePool::Allocation ExecutablePool::systemAlloc(size_t n)
  46 {
  47     void* allocation = mmap(NULL, n, INITIAL_PROTECTION_FLAGS, MAP_PRIVATE | MAP_ANON, VM_TAG_FOR_EXECUTABLEALLOCATOR_MEMORY, 0);
  48     if (allocation == MAP_FAILED)
  49         CRASH();
  50     ExecutablePool::Allocation alloc = { reinterpret_cast<char*>(allocation), n };
  51     return alloc;
  52 }
  53
  54 void ExecutablePool::systemRelease(const ExecutablePool::Allocation& alloc)
  55 {
  56     int result = munmap(alloc.pages, alloc.size);
  57     ASSERT_UNUSED(result, !result);
  58 }
  59
  60 #endif // !(OS(DARWIN) && CPU(X86_64))
  61
  62 #if ENABLE(ASSEMBLER_WX_EXCLUSIVE)
  63 void ExecutableAllocator::reprotectRegion(void* start, size_t size, ProtectionSeting setting)
  64 {
  65     if (!pageSize)
  66         intializePageSize();
  67
  68     // Calculate the start of the page containing this region,
  69     // and account for this extra memory within size.
  70     intptr_t startPtr = reinterpret_cast<intptr_t>(start);
  71     intptr_t pageStartPtr = startPtr & ~(pageSize - 1);
  72     void* pageStart = reinterpret_cast<void*>(pageStartPtr);
  73     size += (startPtr - pageStartPtr);
  74
  75     // Round size up
  76     size += (pageSize - 1);
  77     size &= ~(pageSize - 1);
  78
  79     mprotect(pageStart, size, (setting == Writable) ? PROTECTION_FLAGS_RW : PROTECTION_FLAGS_RX);
  80 }
  81 #endif
  82
  83 }
  84
  85 #endif // HAVE(ASSEMBLER)