WebKit/Source/JavaScriptCore/tools/HeapVerifier.cpp at main · WebKit/WebKit · GitHub

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* 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 "HeapVerifier.h"

#include "ButterflyInlines.h"

#include "CodeBlockInlines.h"

#include "JSObject.h"

#include "MarkedSpaceInlines.h"

#include "VMManager.h"

#include "ValueProfile.h"

#include <wtf/ProcessID.h>

#include <wtf/TZoneMallocInlines.h>

WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN

namespace JSC {

WTF_MAKE_TZONE_ALLOCATED_IMPL(HeapVerifier);

HeapVerifier::HeapVerifier(Heap* heap, unsigned numberOfGCCyclesToRecord)

: m_heap(heap)

, m_currentCycle(0)

, m_numberOfCycles(numberOfGCCyclesToRecord)

{

RELEASE_ASSERT(m_numberOfCycles > 0);

m_cycles = makeUniqueArray<GCCycle>(m_numberOfCycles);

}

const char* HeapVerifier::phaseName(HeapVerifier::Phase phase)

{

switch (phase) {

case Phase::BeforeGC:

return "BeforeGC";

case Phase::BeforeMarking:

return "BeforeMarking";

case Phase::AfterMarking:

return "AfterMarking";

case Phase::AfterGC:

return "AfterGC";

}

RELEASE_ASSERT_NOT_REACHED();

return nullptr; // Silencing a compiler warning.

}

void HeapVerifier::startGC()

{

Heap* heap = m_heap;

incrementCycle();

currentCycle().reset();

currentCycle().scope = *heap->collectionScope();

currentCycle().timestamp = MonotonicTime::now();

ASSERT(!m_didPrintLogs);

}

void HeapVerifier::endGC()

{

if (m_didPrintLogs) {

dataLog("END ");

printVerificationHeader();

dataLog("\n\n");

m_didPrintLogs = false;

}

void HeapVerifier::gatherLiveCells(HeapVerifier::Phase phase)

{

Heap* heap = m_heap;

CellList& list = *cellListForGathering(phase);

list.reset();

heap->m_objectSpace.forEachLiveCell([&list] (HeapCell* cell, HeapCell::Kind kind) {

list.add({ cell, kind, CellProfile::Live });

return IterationStatus::Continue;

});

}

CellList* HeapVerifier::cellListForGathering(HeapVerifier::Phase phase)

{

switch (phase) {

case Phase::BeforeMarking:

return &currentCycle().before;

case Phase::AfterMarking:

return &currentCycle().after;

case Phase::BeforeGC:

case Phase::AfterGC:

// We should not be gathering live cells during these phases.

break;

}

RELEASE_ASSERT_NOT_REACHED();

return nullptr; // Silencing a compiler warning.

}

static void trimDeadCellsFromList(CellList& knownLiveSet, CellList& list)

{

if (!list.size())

return;

for (auto& cellProfile : list.cells()) {

if (cellProfile.isDead())

continue; // Don't "resurrect" known dead cells.

if (!knownLiveSet.find(cellProfile.cell())) {

cellProfile.setIsDead();

continue;

}

cellProfile.setIsLive();

}

void HeapVerifier::trimDeadCells()

{

CellList& knownLiveSet = currentCycle().after;

trimDeadCellsFromList(knownLiveSet, currentCycle().before);

for (int i = -1; i > -m_numberOfCycles; i--) {

trimDeadCellsFromList(knownLiveSet, cycleForIndex(i).before);

trimDeadCellsFromList(knownLiveSet, cycleForIndex(i).after);

}

void HeapVerifier::printVerificationHeader()

{

RELEASE_ASSERT(m_heap->collectionScope());

CollectionScope scope = currentCycle().scope;

MonotonicTime gcCycleTimestamp = currentCycle().timestamp;

dataLog("Verifying heap in [p", getCurrentProcessID(), ", ", Thread::currentSingleton(), "] vm ",

RawPointer(&m_heap->vm()), " on ", scope, " GC @ ", gcCycleTimestamp, "\n");

}

bool HeapVerifier::verifyCellList(Phase phase, CellList& list)

{

VM& vm = m_heap->vm();

auto& liveCells = list.cells();

bool listNamePrinted = false;

auto printHeaderIfNeeded = [&] () {

if (listNamePrinted)

return;

printVerificationHeader();

dataLog(" @ phase ", phaseName(phase), ": FAILED in cell list '", list.name(), "' (size ", liveCells.size(), ")\n");

listNamePrinted = true;

m_didPrintLogs = true;

};

bool success = true;

for (size_t i = 0; i < liveCells.size(); i++) {

CellProfile& profile = liveCells[i];

if (!profile.isLive())

continue;

if (!profile.isJSCell())

continue;

JSCell* cell = profile.jsCell();

if (!validateJSCell(&vm, cell, &profile, &list, printHeaderIfNeeded, " "))

success = false;

}

return success;

}

bool HeapVerifier::validateCell(HeapCell* cell, VM* expectedVM)

{

auto printNothing = [] () { };

if (cell->isZapped()) {

dataLog(" cell ", RawPointer(cell), " is ZAPPED\n");

return false;

}

if (!isJSCellKind(cell->cellKind()))

return true; // Nothing more to validate.

JSCell* jsCell = static_cast<JSCell*>(cell);

return validateJSCell(expectedVM, jsCell, nullptr, nullptr, printNothing);

}

bool HeapVerifier::validateJSCell(VM* expectedVM, JSCell* cell, CellProfile* profile, CellList* list, const ScopedLambda<void()>& printHeaderIfNeeded, const char* prefix)

{

auto printHeaderAndCell = [cell, profile, &printHeaderIfNeeded, prefix] () {

printHeaderIfNeeded();

dataLog(prefix, "cell ", RawPointer(cell));

if (profile)

dataLog(" [", profile->className(), "]");

};

// 1. Validate the cell.

if (cell->isZapped()) {

printHeaderAndCell();

dataLog(" is zapped\n");

return false;

}

StructureID structureID = cell->structureID();

if (!structureID) {

printHeaderAndCell();

dataLog(" has NULL structureID\n");

return false;

}

if (expectedVM) {

VM* cellVM = &cell->vm();

if (cellVM != expectedVM) {

printHeaderAndCell();

dataLog(" is from a different VM: expected:", RawPointer(expectedVM), " actual:", RawPointer(cellVM), "\n");

return false;

}

// 2. Validate the cell's structure

Structure* structure = structureID.decode();

if (!structure) {

printHeaderAndCell();

uint32_t structureIDAsUint32 = structureID.bits();

dataLog(" with structureID ", structureIDAsUint32, " maps to a NULL Structure pointer\n");

return false;

}

if (structure->isZapped()) {

printHeaderAndCell();

dataLog(" has ZAPPED structure ", RawPointer(structure), "\n");

return false;

}

if (!structure->structureID()) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structureID is NULL\n");

return false;

}

VM* structureVM = &structure->vm();

if (structureVM != expectedVM) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " from a different VM: expected:", RawPointer(expectedVM), " actual:", RawPointer(structureVM), "\n");

return false;

}

if (list) {

auto* structureProfile = list->find(structure);

if (!structureProfile) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " NOT found in the live cell list\n");

return false;

}

if (!structureProfile->isLive()) {

printHeaderAndCell();

dataLog(" has DEAD structure ", RawPointer(structure), "\n");

return false;

}

StructureID structureStructureID = structure->structureID();

if (!structureStructureID) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " with a NULL structureID\n");

return false;

}

// 3. Validate the cell's structure's structure.

Structure* structureStructure = structureStructureID.decode();

if (!structureStructure) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structure is NULL\n");

return false;

}

if (structureStructure->isZapped()) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structure ", RawPointer(structureStructure), " is ZAPPED\n");

return false;

}

if (!structureStructure->structureID()) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structure ", RawPointer(structureStructure), " has a NULL structureID\n");

return false;

}

VM* structureStructureVM = &structureStructure->vm();

if (structureStructureVM != expectedVM) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structure ", RawPointer(structureStructure), " is from a different VM: expected:", RawPointer(expectedVM), " actual:", RawPointer(structureStructureVM), "\n");

return false;

}

if (list) {

auto* structureStructureProfile = list->find(structureStructure);

if (!structureStructureProfile) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structure ", RawPointer(structureStructure), " is NOT found in the live cell list\n");

return false;

}

if (!structureStructureProfile->isLive()) {

printHeaderAndCell();

dataLog(" has structure ", RawPointer(structure), " whose structure ", RawPointer(structureStructure), " is DEAD\n");

return false;

}

CodeBlock* codeBlock = dynamicDowncast<CodeBlock>(cell);

if (codeBlock) [[unlikely]] {

bool success = true;

codeBlock->forEachValueProfile([&](auto& valueProfile, bool) {

for (unsigned i = 0; i < std::remove_reference_t<decltype(valueProfile)>::totalNumberOfBuckets; ++i) {

JSValue value = JSValue::decode(valueProfile.m_buckets[i]);

if (!value)

continue;

if (!value.isCell())

continue;

JSCell* valueCell = value.asCell();

if (valueCell->isZapped()) {

printHeaderIfNeeded();

dataLog(prefix, "CodeBlock ", RawPointer(codeBlock), " has ZAPPED ValueProfile cell ", RawPointer(valueCell), "\n");

success = false;

continue;

}

});

if (!success)

return false;

}

return true;

}

void HeapVerifier::verify(HeapVerifier::Phase phase)

{

if (phase == Phase::AfterGC) {

bool verified = verifyCellList(phase, currentCycle().after);

RELEASE_ASSERT(verified);

}

void HeapVerifier::reportCell(CellProfile& profile, int cycleIndex, HeapVerifier::GCCycle& cycle, CellList& list, const char* prefix)

{

HeapCell* cell = profile.cell();

VM& vm = m_heap->vm();

if (prefix)

dataLog(prefix);

dataLog("FOUND");

if (profile.isLive())

dataLog(" LIVE");

else if (profile.isDead())

dataLog(" DEAD");

if (!profile.isJSCell())

dataLog(" HeapCell ");

else

dataLog(" JSCell ");

dataLog(RawPointer(cell));

if (profile.className())

dataLog(" [", profile.className(), "]");

if (profile.isLive() && profile.isJSCell()) {

JSCell* jsCell = profile.jsCell();

Structure* structure = jsCell->structure();

dataLog(" structure:", RawPointer(structure));

if (jsCell->isObject()) {

JSObject* obj = static_cast<JSObject*>(cell);

Butterfly* butterfly = obj->butterfly();

void* butterflyBase = butterfly->base(structure);

dataLog(" butterfly:", RawPointer(butterfly), " (base:", RawPointer(butterflyBase), ")");

}

dataLog(" in ", cycle.scope, " GC[", cycleIndex, "] in '", list.name(), "' list in VM ",

RawPointer(&vm), " recorded at time ", profile.timestamp(), "\n");

if (profile.stackTrace())

dataLog(*profile.stackTrace());

}

void HeapVerifier::checkIfRecorded(HeapCell* cell)

{

bool found = false;

const char* const prefix = " ";

static constexpr bool verbose = true;

for (int cycleIndex = 0; cycleIndex > -m_numberOfCycles; cycleIndex--) {

GCCycle& cycle = cycleForIndex(cycleIndex);

CellList* lists[] = { &cycle.before, &cycle.after };

if (verbose)

dataLog("Checking ", cycle.scope, " GC<", cycle.timestamp, ">, cycle [", cycleIndex, "]:\n");

const char* resultPrefix = " ";

for (auto* list : lists) {

if (verbose)

dataLog(prefix, "Cycle [", cycleIndex, "] '", list->name(), "' list: ");

CellProfile* profile = list->find(cell);

if (profile) {

reportCell(*profile, cycleIndex, cycle, *list, resultPrefix);

found = true;

} else if (verbose)

dataLog(resultPrefix, "cell NOT found\n");

}

if (!found)

dataLog(prefix, "cell ", RawPointer(cell), " NOT FOUND\n");

}

// The following are slower but more robust versions of the corresponding functions of the same name.

// These robust versions are designed so that we can call them interactively from a C++ debugger

// to query if a candidate is recorded cell.

void HeapVerifier::checkIfRecorded(uintptr_t candidateCell)

{

HeapCell* candidateHeapCell = reinterpret_cast<HeapCell*>(candidateCell);

auto result = VMManager::forEachVMWithTimeout(2_s, [&] (VM& vm) {

if (!vm.isInService())

return IterationStatus::Continue;

if (!vm.heap.m_verifier)

return IterationStatus::Continue;

auto* verifier = vm.heap.m_verifier.get();

dataLog("Search for cell ", RawPointer(candidateHeapCell), " in VM ", RawPointer(&vm), ":\n");

verifier->checkIfRecorded(candidateHeapCell);

return IterationStatus::Continue;

});

if (result == VMManager::Error::TimedOut)

dataLog("ERROR: Timed out while waiting to iterate VMs.");

}

} // namespace JSC

WTF_ALLOW_UNSAFE_BUFFER_USAGE_END

WebKit/Source/JavaScriptCore/tools/HeapVerifier.cpp at main · WebKit/WebKit · GitHub

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