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/*
* Copyright (C) 2017-2018 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 "WasmFaultSignalHandler.h"
#if ENABLE(WEBASSEMBLY)
#include "ExecutableAllocator.h"
#include "MachineContext.h"
#include "WasmExceptionType.h"
#include "WasmMemory.h"
#include "WasmThunks.h"
#include <wtf/HashSet.h>
#include <wtf/Lock.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/threads/Signals.h>
namespace JSC { namespace Wasm {
namespace {
namespace WasmFaultSignalHandlerInternal {
static const bool verbose = false;
}
}
static Lock codeLocationsLock;
static LazyNeverDestroyed<HashSet<std::tuple<void*, void*>>> codeLocations; // (start, end)
#if ENABLE(WEBASSEMBLY_FAST_MEMORY)
static bool fastHandlerInstalled { false };
static SignalAction trapHandler(Signal, SigInfo& sigInfo, PlatformRegisters& context)
{
void* faultingInstruction = MachineContext::instructionPointer(context).untaggedExecutableAddress();
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "starting handler for fault at: ", RawPointer(faultingInstruction));
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "JIT memory start: ", RawPointer(reinterpret_cast<void*>(startOfFixedExecutableMemoryPool)), " end: ", RawPointer(reinterpret_cast<void*>(endOfFixedExecutableMemoryPool)));
// First we need to make sure we are in JIT code before we can aquire any locks. Otherwise,
// we might have crashed in code that is already holding one of the locks we want to aquire.
assertIsNotTagged(faultingInstruction);
if (isJITPC(faultingInstruction)) {
bool faultedInActiveFastMemory = false;
{
void* faultingAddress = sigInfo.faultingAddress;
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "checking faulting address: ", RawPointer(faultingAddress), " is in an active fast memory");
faultedInActiveFastMemory = Wasm::Memory::addressIsInActiveFastMemory(faultingAddress);
}
if (faultedInActiveFastMemory) {
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "found active fast memory for faulting address");
LockHolder locker(codeLocationsLock);
for (auto range : codeLocations.get()) {
void* start;
void* end;
std::tie(start, end) = range;
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "function start: ", RawPointer(start), " end: ", RawPointer(end));
if (start <= faultingInstruction && faultingInstruction < end) {
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "found match");
MacroAssemblerCodeRef<JITThunkPtrTag> exceptionStub = Thunks::singleton().existingStub(throwExceptionFromWasmThunkGenerator);
// If for whatever reason we don't have a stub then we should just treat this like a regular crash.
if (!exceptionStub)
break;
dataLogLnIf(WasmFaultSignalHandlerInternal::verbose, "found stub: ", RawPointer(exceptionStub.code().executableAddress()));
MachineContext::argumentPointer<1>(context) = reinterpret_cast<void*>(ExceptionType::OutOfBoundsMemoryAccess);
MachineContext::setInstructionPointer(context, exceptionStub.code().retagged<CFunctionPtrTag>());
return SignalAction::Handled;
}
}
}
}
return SignalAction::NotHandled;
}
#endif // ENABLE(WEBASSEMBLY_FAST_MEMORY)
void registerCode(void* start, void* end)
{
if (!fastMemoryEnabled())
return;
LockHolder locker(codeLocationsLock);
codeLocations->add(std::make_tuple(start, end));
}
void unregisterCode(void* start, void* end)
{
if (!fastMemoryEnabled())
return;
LockHolder locker(codeLocationsLock);
codeLocations->remove(std::make_tuple(start, end));
}
bool fastMemoryEnabled()
{
return fastHandlerInstalled;
}
void enableFastMemory()
{
static std::once_flag once;
std::call_once(once, [] {
if (!Options::useWebAssemblyFastMemory())
return;
#if ENABLE(WEBASSEMBLY_FAST_MEMORY)
installSignalHandler(Signal::BadAccess, [] (Signal signal, SigInfo& sigInfo, PlatformRegisters& ucontext) {
return trapHandler(signal, sigInfo, ucontext);
});
codeLocations.construct();
fastHandlerInstalled = true;
#endif // ENABLE(WEBASSEMBLY_FAST_MEMORY)
});
}
} } // namespace JSC::Wasm
#endif // ENABLE(WEBASSEMBLY)