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/*
* Copyright (C) 2017-2019 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 "VMInspector.h"
#include "CodeBlock.h"
#include "CodeBlockSet.h"
#include "HeapInlines.h"
#include "HeapIterationScope.h"
#include "JSCInlines.h"
#include "MachineContext.h"
#include "MarkedSpaceInlines.h"
#include "StackVisitor.h"
#include <mutex>
#include <wtf/Expected.h>
#if !OS(WINDOWS)
#include <unistd.h>
#endif
namespace JSC {
VMInspector& VMInspector::instance()
{
static VMInspector* manager;
static std::once_flag once;
std::call_once(once, [] {
manager = new VMInspector();
});
return *manager;
}
void VMInspector::add(VM* vm)
{
auto locker = holdLock(m_lock);
m_vmList.append(vm);
}
void VMInspector::remove(VM* vm)
{
auto locker = holdLock(m_lock);
m_vmList.remove(vm);
}
auto VMInspector::lock(Seconds timeout) -> Expected<Locker, Error>
{
// This function may be called from a signal handler (e.g. via visit()). Hence,
// it should only use APIs that are safe to call from signal handlers. This is
// why we use unistd.h's sleep() instead of its alternatives.
// We'll be doing sleep(1) between tries below. Hence, sleepPerRetry is 1.
unsigned maxRetries = (timeout < Seconds::infinity()) ? timeout.value() : UINT_MAX;
Expected<Locker, Error> locker = Locker::tryLock(m_lock);
unsigned tryCount = 0;
while (!locker && tryCount < maxRetries) {
// We want the version of sleep from unistd.h. Cast to disambiguate.
#if !OS(WINDOWS)
(static_cast<unsigned (*)(unsigned)>(sleep))(1);
#endif
locker = Locker::tryLock(m_lock);
}
if (!locker)
return makeUnexpected(Error::TimedOut);
return locker;
}
#if ENABLE(JIT)
static bool ensureIsSafeToLock(Lock& lock)
{
unsigned maxRetries = 2;
unsigned tryCount = 0;
while (tryCount <= maxRetries) {
bool success = lock.tryLock();
if (success) {
lock.unlock();
return true;
}
tryCount++;
}
return false;
};
#endif // ENABLE(JIT)
auto VMInspector::isValidExecutableMemory(const VMInspector::Locker&, void* machinePC) -> Expected<bool, Error>
{
#if ENABLE(JIT)
bool found = false;
bool hasTimeout = false;
iterate([&] (VM&) -> FunctorStatus {
auto& allocator = ExecutableAllocator::singleton();
auto& lock = allocator.getLock();
bool isSafeToLock = ensureIsSafeToLock(lock);
if (!isSafeToLock) {
hasTimeout = true;
return FunctorStatus::Continue; // Skip this VM.
}
LockHolder executableAllocatorLocker(lock);
if (allocator.isValidExecutableMemory(executableAllocatorLocker, machinePC)) {
found = true;
return FunctorStatus::Done;
}
return FunctorStatus::Continue;
});
if (!found && hasTimeout)
return makeUnexpected(Error::TimedOut);
return found;
#else
UNUSED_PARAM(machinePC);
return false;
#endif
}
auto VMInspector::codeBlockForMachinePC(const VMInspector::Locker&, void* machinePC) -> Expected<CodeBlock*, Error>
{
#if ENABLE(JIT)
CodeBlock* codeBlock = nullptr;
bool hasTimeout = false;
iterate([&] (VM& vm) {
if (!vm.currentThreadIsHoldingAPILock())
return FunctorStatus::Continue;
// It is safe to call Heap::forEachCodeBlockIgnoringJITPlans here because:
// 1. CodeBlocks are added to the CodeBlockSet from the main thread before
// they are handed to the JIT plans. Those codeBlocks will have a null jitCode,
// but we check for that in our lambda functor.
// 2. We will acquire the CodeBlockSet lock before iterating.
// This ensures that a CodeBlock won't be GCed while we're iterating.
// 3. We do a tryLock on the CodeBlockSet's lock first to ensure that it is
// safe for the current thread to lock it before calling
// Heap::forEachCodeBlockIgnoringJITPlans(). Hence, there's no risk of
// re-entering the lock and deadlocking on it.
auto& codeBlockSetLock = vm.heap.codeBlockSet().getLock();
bool isSafeToLock = ensureIsSafeToLock(codeBlockSetLock);
if (!isSafeToLock) {
hasTimeout = true;
return FunctorStatus::Continue; // Skip this VM.
}
auto locker = holdLock(codeBlockSetLock);
vm.heap.forEachCodeBlockIgnoringJITPlans(locker, [&] (CodeBlock* cb) {
JITCode* jitCode = cb->jitCode().get();
if (!jitCode) {
// If the codeBlock is a replacement codeBlock which is in the process of being
// compiled, its jitCode will be null, and we can disregard it as a match for
// the machinePC we're searching for.
return;
}
if (!JITCode::isJIT(jitCode->jitType()))
return;
if (jitCode->contains(machinePC)) {
codeBlock = cb;
return;
}
});
if (codeBlock)
return FunctorStatus::Done;
return FunctorStatus::Continue;
});
if (!codeBlock && hasTimeout)
return makeUnexpected(Error::TimedOut);
return codeBlock;
#else
UNUSED_PARAM(machinePC);
return nullptr;
#endif
}
bool VMInspector::currentThreadOwnsJSLock(ExecState* exec)
{
return exec->vm().currentThreadIsHoldingAPILock();
}
static bool ensureCurrentThreadOwnsJSLock(ExecState* exec)
{
if (VMInspector::currentThreadOwnsJSLock(exec))
return true;
dataLog("ERROR: current thread does not own the JSLock\n");
return false;
}
void VMInspector::gc(ExecState* exec)
{
VM& vm = exec->vm();
if (!ensureCurrentThreadOwnsJSLock(exec))
return;
vm.heap.collectNow(Sync, CollectionScope::Full);
}
void VMInspector::edenGC(ExecState* exec)
{
VM& vm = exec->vm();
if (!ensureCurrentThreadOwnsJSLock(exec))
return;
vm.heap.collectSync(CollectionScope::Eden);
}
bool VMInspector::isInHeap(Heap* heap, void* ptr)
{
MarkedBlock* candidate = MarkedBlock::blockFor(ptr);
if (heap->objectSpace().blocks().set().contains(candidate))
return true;
for (LargeAllocation* allocation : heap->objectSpace().largeAllocations()) {
if (allocation->contains(ptr))
return true;
}
return false;
}
struct CellAddressCheckFunctor : MarkedBlock::CountFunctor {
CellAddressCheckFunctor(JSCell* candidate)
: candidate(candidate)
{
}
IterationStatus operator()(HeapCell* cell, HeapCell::Kind) const
{
if (cell == candidate) {
found = true;
return IterationStatus::Done;
}
return IterationStatus::Continue;
}
JSCell* candidate;
mutable bool found { false };
};
bool VMInspector::isValidCell(Heap* heap, JSCell* candidate)
{
HeapIterationScope iterationScope(*heap);
CellAddressCheckFunctor functor(candidate);
heap->objectSpace().forEachLiveCell(iterationScope, functor);
return functor.found;
}
bool VMInspector::isValidCodeBlock(ExecState* exec, CodeBlock* candidate)
{
if (!ensureCurrentThreadOwnsJSLock(exec))
return false;
struct CodeBlockValidationFunctor {
CodeBlockValidationFunctor(CodeBlock* candidate)
: candidate(candidate)
{
}
void operator()(CodeBlock* codeBlock) const
{
if (codeBlock == candidate)
found = true;
}
CodeBlock* candidate;
mutable bool found { false };
};
VM& vm = exec->vm();
CodeBlockValidationFunctor functor(candidate);
vm.heap.forEachCodeBlock(functor);
return functor.found;
}
CodeBlock* VMInspector::codeBlockForFrame(CallFrame* topCallFrame, unsigned frameNumber)
{
if (!ensureCurrentThreadOwnsJSLock(topCallFrame))
return nullptr;
if (!topCallFrame)
return nullptr;
struct FetchCodeBlockFunctor {
public:
FetchCodeBlockFunctor(unsigned targetFrameNumber)
: targetFrame(targetFrameNumber)
{
}
StackVisitor::Status operator()(StackVisitor& visitor) const
{
auto currentFrame = nextFrame++;
if (currentFrame == targetFrame) {
codeBlock = visitor->codeBlock();
return StackVisitor::Done;
}
return StackVisitor::Continue;
}
unsigned targetFrame;
mutable unsigned nextFrame { 0 };
mutable CodeBlock* codeBlock { nullptr };
};
FetchCodeBlockFunctor functor(frameNumber);
topCallFrame->iterate(functor);
return functor.codeBlock;
}
class DumpFrameFunctor {
public:
enum Action {
DumpOne,
DumpAll
};
DumpFrameFunctor(Action action, unsigned framesToSkip)
: m_action(action)
, m_framesToSkip(framesToSkip)
{
}
StackVisitor::Status operator()(StackVisitor& visitor) const
{
m_currentFrame++;
if (m_currentFrame > m_framesToSkip) {
visitor->dump(WTF::dataFile(), Indenter(2), [&] (PrintStream& out) {
out.print("[", (m_currentFrame - m_framesToSkip - 1), "] ");
});
}
if (m_action == DumpOne && m_currentFrame > m_framesToSkip)
return StackVisitor::Done;
return StackVisitor::Continue;
}
private:
Action m_action;
unsigned m_framesToSkip;
mutable unsigned m_currentFrame { 0 };
};
void VMInspector::dumpCallFrame(CallFrame* callFrame, unsigned framesToSkip)
{
if (!ensureCurrentThreadOwnsJSLock(callFrame))
return;
DumpFrameFunctor functor(DumpFrameFunctor::DumpOne, framesToSkip);
callFrame->iterate(functor);
}
void VMInspector::dumpRegisters(CallFrame* callFrame)
{
CodeBlock* codeBlock = callFrame->codeBlock();
if (!codeBlock) {
dataLog("Dumping host frame registers not supported.\n");
return;
}
VM& vm = codeBlock->vm();
auto valueAsString = [&] (JSValue v) -> CString {
if (!v.isCell() || VMInspector::isValidCell(&vm.heap, reinterpret_cast<JSCell*>(JSValue::encode(v))))
return toCString(v);
return "";
};
dataLogF("Register frame: \n\n");
dataLogF("-----------------------------------------------------------------------------\n");
dataLogF(" use | address | value \n");
dataLogF("-----------------------------------------------------------------------------\n");
const Register* it;
const Register* end;
it = callFrame->registers() + CallFrameSlot::thisArgument + callFrame->argumentCount();
end = callFrame->registers() + CallFrameSlot::thisArgument - 1;
while (it > end) {
JSValue v = it->jsValue();
int registerNumber = it - callFrame->registers();
String name = codeBlock->nameForRegister(VirtualRegister(registerNumber));
dataLogF("[r% 3d %14s] | %10p | 0x%-16llx %s\n", registerNumber, name.ascii().data(), it, (long long)JSValue::encode(v), valueAsString(v).data());
--it;
}
dataLogF("-----------------------------------------------------------------------------\n");
dataLogF("[ArgumentCount] | %10p | %lu \n", it, (unsigned long) callFrame->argumentCount());
callFrame->iterate([&] (StackVisitor& visitor) {
if (visitor->callFrame() == callFrame) {
unsigned line = 0;
unsigned unusedColumn = 0;
visitor->computeLineAndColumn(line, unusedColumn);
dataLogF("[ReturnVPC] | %10p | %d (line %d)\n", it, visitor->bytecodeOffset(), line);
return StackVisitor::Done;
}
return StackVisitor::Continue;
});
--it;
dataLogF("[Callee] | %10p | 0x%-16llx %s\n", it, (long long)callFrame->callee().rawPtr(), valueAsString(it->jsValue()).data());
--it;
dataLogF("[CodeBlock] | %10p | 0x%-16llx ", it, (long long)codeBlock);
dataLogLn(codeBlock);
--it;
#if ENABLE(JIT)
AbstractPC pc = callFrame->abstractReturnPC(callFrame->vm());
if (pc.hasJITReturnAddress())
dataLogF("[ReturnPC] | %10p | %p \n", it, pc.jitReturnAddress().value());
--it;
#endif
dataLogF("[CallerFrame] | %10p | %p \n", it, callFrame->callerFrame());
--it;
dataLogF("-----------------------------------------------------------------------------\n");
size_t numberOfCalleeSaveSlots = codeBlock->calleeSaveSpaceAsVirtualRegisters();
const Register* endOfCalleeSaves = it - numberOfCalleeSaveSlots;
end = it - codeBlock->numVars();
if (it != end) {
do {
JSValue v = it->jsValue();
int registerNumber = it - callFrame->registers();
String name = (it > endOfCalleeSaves)
? "CalleeSaveReg"
: codeBlock->nameForRegister(VirtualRegister(registerNumber));
dataLogF("[r% 3d %14s] | %10p | 0x%-16llx %s\n", registerNumber, name.ascii().data(), it, (long long)JSValue::encode(v), valueAsString(v).data());
--it;
} while (it != end);
}
dataLogF("-----------------------------------------------------------------------------\n");
end = it - codeBlock->numCalleeLocals() + codeBlock->numVars();
if (it != end) {
do {
JSValue v = (*it).jsValue();
int registerNumber = it - callFrame->registers();
dataLogF("[r% 3d] | %10p | 0x%-16llx %s\n", registerNumber, it, (long long)JSValue::encode(v), valueAsString(v).data());
--it;
} while (it != end);
}
dataLogF("-----------------------------------------------------------------------------\n");
}
void VMInspector::dumpStack(CallFrame* topCallFrame, unsigned framesToSkip)
{
if (!ensureCurrentThreadOwnsJSLock(topCallFrame))
return;
if (!topCallFrame)
return;
DumpFrameFunctor functor(DumpFrameFunctor::DumpAll, framesToSkip);
topCallFrame->iterate(functor);
}
void VMInspector::dumpValue(JSValue value)
{
dataLogLn(value);
}
void VMInspector::dumpCellMemory(JSCell* cell)
{
dumpCellMemoryToStream(cell, WTF::dataFile());
}
class IndentationScope {
public:
IndentationScope(unsigned& indentation)
: m_indentation(indentation)
{
++m_indentation;
}
~IndentationScope()
{
--m_indentation;
}
private:
unsigned& m_indentation;
};
void VMInspector::dumpCellMemoryToStream(JSCell* cell, PrintStream& out)
{
VM& vm = cell->vm();
StructureID structureID = cell->structureID();
Structure* structure = cell->structure(vm);
IndexingType indexingTypeAndMisc = cell->indexingTypeAndMisc();
IndexingType indexingType = structure->indexingType();
IndexingType indexingMode = structure->indexingMode();
JSType type = cell->type();
TypeInfo::InlineTypeFlags inlineTypeFlags = cell->inlineTypeFlags();
CellState cellState = cell->cellState();
size_t cellSize = cell->cellSize();
size_t slotCount = cellSize / sizeof(EncodedJSValue);
EncodedJSValue* slots = bitwise_cast<EncodedJSValue*>(cell);
unsigned indentation = 0;
auto indent = [&] {
for (unsigned i = 0 ; i < indentation; ++i)
out.print(" ");
};
#define INDENT indent(),
auto dumpSlot = [&] (EncodedJSValue* slots, unsigned index, const char* label = nullptr) {
out.print("[", index, "] ", format("%p : 0x%016" PRIx64, &slots[index], slots[index]));
if (label)
out.print(" ", label);
out.print("\n");
};
out.printf("<%p, %s>\n", cell, cell->className(vm));
IndentationScope scope(indentation);
INDENT dumpSlot(slots, 0, "header");
{
IndentationScope scope(indentation);
INDENT out.println("structureID ", format("%d 0x%" PRIx32, structureID, structureID), " structure ", RawPointer(structure));
INDENT out.println("indexingTypeAndMisc ", format("%d 0x%" PRIx8, indexingTypeAndMisc, indexingTypeAndMisc), " ", IndexingTypeDump(indexingMode));
INDENT out.println("type ", format("%d 0x%" PRIx8, type, type));
INDENT out.println("flags ", format("%d 0x%" PRIx8, inlineTypeFlags, inlineTypeFlags));
INDENT out.println("cellState ", format("%d", cellState));
}
unsigned slotIndex = 1;
if (cell->isObject()) {
JSObject* obj = static_cast<JSObject*>(const_cast<JSCell*>(cell));
Butterfly* butterfly = obj->butterfly();
size_t butterflySize = obj->butterflyTotalSize();
INDENT dumpSlot(slots, slotIndex, "butterfly");
slotIndex++;
if (butterfly) {
IndentationScope scope(indentation);
bool hasIndexingHeader = structure->hasIndexingHeader(cell);
bool hasAnyArrayStorage = JSC::hasAnyArrayStorage(indexingType);
size_t preCapacity = obj->butterflyPreCapacity();
size_t propertyCapacity = structure->outOfLineCapacity();
void* base = hasIndexingHeader
? butterfly->base(preCapacity, propertyCapacity)
: butterfly->base(structure);
unsigned publicLength = butterfly->publicLength();
unsigned vectorLength = butterfly->vectorLength();
size_t butterflyCellSize = MarkedSpace::optimalSizeFor(butterflySize);
size_t endOfIndexedPropertiesIndex = butterflySize / sizeof(EncodedJSValue);
size_t endOfButterflyIndex = butterflyCellSize / sizeof(EncodedJSValue);
INDENT out.println("base ", RawPointer(base));
INDENT out.println("hasIndexingHeader ", (hasIndexingHeader ? "YES" : "NO"), " hasAnyArrayStorage ", (hasAnyArrayStorage ? "YES" : "NO"));
if (hasIndexingHeader) {
INDENT out.print("publicLength ", publicLength, " vectorLength ", vectorLength);
if (hasAnyArrayStorage)
out.print(" indexBias ", butterfly->arrayStorage()->m_indexBias);
out.print("\n");
}
INDENT out.println("preCapacity ", preCapacity, " propertyCapacity ", propertyCapacity);
unsigned index = 0;
EncodedJSValue* slots = reinterpret_cast<EncodedJSValue*>(base);
auto asVoidPtr = [] (void* p) {
return p;
};
auto dumpSectionHeader = [&] (const char* name) {
out.println("<--- ", name);
};
auto dumpSection = [&] (unsigned startIndex, unsigned endIndex, const char* name) -> unsigned {
for (unsigned index = startIndex; index < endIndex; ++index) {
if (name && index == startIndex)
INDENT dumpSectionHeader(name);
INDENT dumpSlot(slots, index);
}
return endIndex;
};
{
IndentationScope scope(indentation);
index = dumpSection(index, preCapacity, "preCapacity");
index = dumpSection(index, preCapacity + propertyCapacity, "propertyCapacity");
if (hasIndexingHeader)
index = dumpSection(index, index + 1, "indexingHeader");
INDENT dumpSectionHeader("butterfly");
if (hasAnyArrayStorage) {
RELEASE_ASSERT(asVoidPtr(butterfly->arrayStorage()) == asVoidPtr(&slots[index]));
RELEASE_ASSERT(ArrayStorage::vectorOffset() == 2 * sizeof(EncodedJSValue));
index = dumpSection(index, index + 2, "arrayStorage");
}
index = dumpSection(index, endOfIndexedPropertiesIndex, "indexedProperties");
index = dumpSection(index, endOfButterflyIndex, "unallocated capacity");
}
}
}
for (; slotIndex < slotCount; ++slotIndex)
INDENT dumpSlot(slots, slotIndex);
#undef INDENT
}
void VMInspector::dumpSubspaceHashes(VM* vm)
{
unsigned count = 0;
vm->heap.objectSpace().forEachSubspace([&] (const Subspace& subspace) -> IterationStatus {
const char* name = subspace.name();
unsigned hash = StringHasher::computeHash(name);
void* hashAsPtr = reinterpret_cast<void*>(static_cast<uintptr_t>(hash));
dataLogLn(" [", count++, "] ", name, " Hash:", RawPointer(hashAsPtr));
return IterationStatus::Continue;
});
dataLogLn();
}
} // namespace JSC