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/*
* Copyright (C) 2016 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
* 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 "WasmMemory.h"
#if ENABLE(WEBASSEMBLY)
#include <wtf/HexNumber.h>
#include <wtf/PrintStream.h>
#include <wtf/text/WTFString.h>
namespace JSC { namespace Wasm {
namespace {
const bool verbose = false;
}
void Memory::dump(PrintStream& out) const
{
String memoryHex;
WTF::appendUnsigned64AsHex((uint64_t)(uintptr_t)m_memory, memoryHex);
out.print("Memory at 0x", memoryHex, ", size ", m_size, "B capacity ", m_mappedCapacity, "B, initial ", m_initial, " maximum ", m_maximum, " mode ", makeString(m_mode));
}
const char* Memory::makeString(Mode mode) const
{
switch (mode) {
case Mode::BoundsChecking: return "BoundsChecking";
}
RELEASE_ASSERT_NOT_REACHED();
return "";
}
static_assert(sizeof(uint64_t) == sizeof(size_t), "We rely on allowing the maximum size of Memory we map to be 2^32 which is larger than fits in a 32-bit integer that we'd pass to mprotect if this didn't hold.");
Memory::Memory(PageCount initial, PageCount maximum, bool& failed)
: m_size(initial.bytes())
, m_initial(initial)
, m_maximum(maximum)
, m_mode(Mode::BoundsChecking)
// FIXME: If we add signal based bounds checking then we need extra space for overflow on load.
// see: https://bugs.webkit.org/show_bug.cgi?id=162693
{
RELEASE_ASSERT(!maximum || maximum >= initial); // This should be guaranteed by our caller.
m_mappedCapacity = maximum ? maximum.bytes() : PageCount::max().bytes();
if (!m_mappedCapacity) {
// This means we specified a zero as maximum (which means we also have zero as initial size).
RELEASE_ASSERT(m_size == 0);
m_memory = nullptr;
m_mappedCapacity = 0;
failed = false;
if (verbose)
dataLogLn("Memory::Memory allocating nothing ", *this);
return;
}
// FIXME: It would be nice if we had a VM tag for wasm memory. https://bugs.webkit.org/show_bug.cgi?id=163600
void* result = Options::simulateWebAssemblyLowMemory() ? MAP_FAILED : mmap(nullptr, m_mappedCapacity, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
if (result == MAP_FAILED) {
// Try again with a different number.
if (verbose)
dataLogLn("Memory::Memory mmap failed once for capacity, trying again", *this);
m_mappedCapacity = m_size;
if (!m_mappedCapacity) {
m_memory = nullptr;
failed = false;
if (verbose)
dataLogLn("Memory::Memory mmap not trying again because size is zero ", *this);
return;
}
result = mmap(nullptr, m_mappedCapacity, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
if (result == MAP_FAILED) {
if (verbose)
dataLogLn("Memory::Memory mmap failed twice ", *this);
failed = true;
return;
}
}
ASSERT(m_size <= m_mappedCapacity);
{
bool success = !mprotect(result, static_cast<size_t>(m_size), PROT_READ | PROT_WRITE);
RELEASE_ASSERT(success);
}
m_memory = result;
failed = false;
if (verbose)
dataLogLn("Memory::Memory mmap succeeded ", *this);
}
Memory::~Memory()
{
if (verbose)
dataLogLn("Memory::~Memory ", *this);
if (m_memory) {
if (munmap(m_memory, m_mappedCapacity))
CRASH();
}
}
bool Memory::grow(PageCount newSize)
{
RELEASE_ASSERT(newSize > PageCount::fromBytes(m_size));
if (verbose)
dataLogLn("Memory::grow to ", newSize, " from ", *this);
if (maximum() && newSize > maximum())
return false;
uint64_t desiredSize = newSize.bytes();
if (m_memory && desiredSize <= m_mappedCapacity) {
bool success = !mprotect(static_cast<uint8_t*>(m_memory) + m_size, static_cast<size_t>(desiredSize - m_size), PROT_READ | PROT_WRITE);
RELEASE_ASSERT(success);
m_size = desiredSize;
if (verbose)
dataLogLn("Memory::grow in-place ", *this);
return true;
}
// Otherwise, let's try to make some new memory.
void* newMemory = mmap(nullptr, desiredSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
if (newMemory == MAP_FAILED)
return false;
if (m_memory) {
memcpy(newMemory, m_memory, m_size);
bool success = !munmap(m_memory, m_mappedCapacity);
RELEASE_ASSERT(success);
}
m_memory = newMemory;
m_mappedCapacity = desiredSize;
m_size = desiredSize;
if (verbose)
dataLogLn("Memory::grow ", *this);
return true;
}
} // namespace JSC
} // namespace Wasm
#endif // ENABLE(WEBASSEMBLY)
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