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      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)
    129