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/*
* Copyright (C) 2008-2017 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "CLoopStack.h"
#if ENABLE(C_LOOP)
#include "CLoopStackInlines.h"
#include "ConservativeRoots.h"
#include "Interpreter.h"
#include "JSCInlines.h"
#include "Options.h"
#include <wtf/Lock.h>
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace JSC {
static size_t committedBytesCount = 0;
static size_t commitSize()
{
static size_t size = std::max<size_t>(16 * 1024, pageSize());
return size;
}
static Lock stackStatisticsMutex;
CLoopStack::CLoopStack(VM& vm)
: m_vm(vm)
, m_topCallFrame(vm.topCallFrame)
, m_softReservedZoneSizeInRegisters(0)
{
size_t capacity = Options::maxPerThreadStackUsage();
capacity = WTF::roundUpToMultipleOf(pageSize(), capacity);
ASSERT(capacity && isPageAligned(capacity));
m_reservation = PageReservation::reserve(WTF::roundUpToMultipleOf(commitSize(), capacity), OSAllocator::UnknownUsage);
auto* bottomOfStack = highAddress();
setCLoopStackLimit(bottomOfStack);
ASSERT(m_end == bottomOfStack);
m_commitTop = bottomOfStack;
m_lastStackPointer = bottomOfStack;
m_currentStackPointer = bottomOfStack;
m_topCallFrame = 0;
}
CLoopStack::~CLoopStack()
{
ptrdiff_t sizeToDecommit = reinterpret_cast<char*>(highAddress()) - reinterpret_cast<char*>(m_commitTop);
m_reservation.decommit(reinterpret_cast<void*>(m_commitTop), sizeToDecommit);
addToCommittedByteCount(-sizeToDecommit);
m_reservation.deallocate();
}
bool CLoopStack::grow(Register* newTopOfStack)
{
Register* newTopOfStackWithReservedZone = newTopOfStack - m_softReservedZoneSizeInRegisters;
// If we have already committed enough memory to satisfy this request,
// just update the end pointer and return.
if (newTopOfStackWithReservedZone >= m_commitTop) {
setCLoopStackLimit(newTopOfStack);
return true;
}
// Compute the chunk size of additional memory to commit, and see if we
// have it still within our budget. If not, we'll fail to grow and
// return false.
ptrdiff_t delta = reinterpret_cast<char*>(m_commitTop) - reinterpret_cast<char*>(newTopOfStackWithReservedZone);
delta = WTF::roundUpToMultipleOf(commitSize(), delta);
Register* newCommitTop = m_commitTop - (delta / sizeof(Register));
if (newCommitTop < reservationTop())
return false;
// Otherwise, the growth is still within our budget. Commit it and return true.
m_reservation.commit(newCommitTop, delta);
addToCommittedByteCount(delta);
m_commitTop = newCommitTop;
newTopOfStack = m_commitTop + m_softReservedZoneSizeInRegisters;
setCLoopStackLimit(newTopOfStack);
return true;
}
void CLoopStack::gatherConservativeRoots(ConservativeRoots& conservativeRoots, JITStubRoutineSet& jitStubRoutines, CodeBlockSet& codeBlocks)
{
conservativeRoots.add(currentStackPointer(), highAddress(), jitStubRoutines, codeBlocks);
}
void CLoopStack::sanitizeStack()
{
#if !ASAN_ENABLED
void* stackTop = currentStackPointer();
ASSERT(stackTop <= highAddress());
if (m_lastStackPointer < stackTop) {
char* begin = reinterpret_cast<char*>(m_lastStackPointer);
char* end = reinterpret_cast<char*>(stackTop);
memset(begin, 0, end - begin);
}
m_lastStackPointer = stackTop;
#endif
}
void CLoopStack::releaseExcessCapacity()
{
Register* highAddressWithReservedZone = highAddress() - m_softReservedZoneSizeInRegisters;
ptrdiff_t delta = reinterpret_cast<char*>(highAddressWithReservedZone) - reinterpret_cast<char*>(m_commitTop);
m_reservation.decommit(m_commitTop, delta);
addToCommittedByteCount(-delta);
m_commitTop = highAddressWithReservedZone;
}
void CLoopStack::addToCommittedByteCount(long byteCount)
{
Locker locker { stackStatisticsMutex };
ASSERT(static_cast<long>(committedBytesCount) + byteCount > -1);
committedBytesCount += byteCount;
}
void CLoopStack::setSoftReservedZoneSize(size_t reservedZoneSize)
{
m_softReservedZoneSizeInRegisters = reservedZoneSize / sizeof(Register);
if (m_commitTop > m_end - m_softReservedZoneSizeInRegisters)
grow(m_end);
}
bool CLoopStack::isSafeToRecurse() const
{
void* reservationLimit = reinterpret_cast<int8_t*>(reservationTop() + m_softReservedZoneSizeInRegisters);
return !m_topCallFrame || (m_topCallFrame->topOfFrame() > reservationLimit);
}
size_t CLoopStack::committedByteCount()
{
Locker locker { stackStatisticsMutex };
return committedBytesCount;
}
} // namespace JSC
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
#endif // ENABLE(C_LOOP)
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