jit/ExecutableAllocator.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)
  31
  32 namespace JSC {
  33
  34 size_t ExecutableAllocator::pageSize = 0;
  35
  36 #if ENABLE(EXECUTABLE_ALLOCATOR_DEMAND)
  37
  38 void ExecutableAllocator::intializePageSize()
  39 {
  40 #if OS(SYMBIAN) && CPU(ARMV5_OR_LOWER)
  41     // The moving memory model (as used in ARMv5 and earlier platforms)
  42     // on Symbian OS limits the number of chunks for each process to 16.
  43     // To mitigate this limitation increase the pagesize to allocate
  44     // fewer, larger chunks. Set the page size to 256 Kb to compensate
  45     // for moving memory model limitation
  46     ExecutableAllocator::pageSize = 256 * 1024;
  47 #else
  48     ExecutableAllocator::pageSize = WTF::pageSize();
  49 #endif
  50 }
  51
  52 ExecutablePool::Allocation ExecutablePool::systemAlloc(size_t size)
  53 {
  54     PageAllocation allocation = PageAllocation::allocate(size, OSAllocator::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true);
  55     if (!allocation)
  56         CRASH();
  57     return allocation;
  58 }
  59
  60 void ExecutablePool::systemRelease(ExecutablePool::Allocation& allocation)
  61 {
  62     allocation.deallocate();
  63 }
  64
  65 bool ExecutableAllocator::isValid() const
  66 {
  67     return true;
  68 }
  69
  70 bool ExecutableAllocator::underMemoryPressure()
  71 {
  72     return false;
  73 }
  74
  75 size_t ExecutableAllocator::committedByteCount()
  76 {
  77     return 0;
  78 }
  79
  80 #endif
  81
  82 #if ENABLE(ASSEMBLER_WX_EXCLUSIVE)
  83
  84 #if OS(WINDOWS) || OS(SYMBIAN)
  85 #error "ASSEMBLER_WX_EXCLUSIVE not yet suported on this platform."
  86 #endif
  87
  88 void ExecutableAllocator::reprotectRegion(void* start, size_t size, ProtectionSetting setting)
  89 {
  90     if (!pageSize)
  91         intializePageSize();
  92
  93     // Calculate the start of the page containing this region,
  94     // and account for this extra memory within size.
  95     intptr_t startPtr = reinterpret_cast<intptr_t>(start);
  96     intptr_t pageStartPtr = startPtr & ~(pageSize - 1);
  97     void* pageStart = reinterpret_cast<void*>(pageStartPtr);
  98     size += (startPtr - pageStartPtr);
  99
 100     // Round size up
 101     size += (pageSize - 1);
 102     size &= ~(pageSize - 1);
 103
 104     mprotect(pageStart, size, (setting == Writable) ? PROTECTION_FLAGS_RW : PROTECTION_FLAGS_RX);
 105 }
 106
 107 #endif
 108
 109 #if CPU(ARM_TRADITIONAL) && OS(LINUX) && COMPILER(RVCT)
 110
 111 __asm void ExecutableAllocator::cacheFlush(void* code, size_t size)
 112 {
 113     ARM
 114     push {r7}
 115     add r1, r1, r0
 116     mov r7, #0xf0000
 117     add r7, r7, #0x2
 118     mov r2, #0x0
 119     svc #0x0
 120     pop {r7}
 121     bx lr
 122 }
 123
 124 #endif
 125
 126 }
 127
 128 #endif // HAVE(ASSEMBLER)