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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifdef MOZ_VALGRIND
# include <valgrind/memcheck.h>
#endif
#include "jstypes.h"
#include "builtin/MapObject.h"
#include "debugger/DebugAPI.h"
#include "frontend/BytecodeCompiler.h"
#include "frontend/Parser.h"
#include "gc/ClearEdgesTracer.h"
#include "gc/GCInternals.h"
#include "gc/Marking.h"
#include "js/HashTable.h"
#include "js/ValueArray.h"
#include "vm/HelperThreadState.h"
#include "vm/JSContext.h"
#include "vm/JSONParser.h"
#include "gc/Nursery-inl.h"
#include "gc/PrivateIterators-inl.h"
#include "vm/JSObject-inl.h"
using namespace js;
using namespace js::gc;
using mozilla::LinkedList;
using JS::AutoGCRooter;
using RootRange = RootedValueMap::Range;
using RootEntry = RootedValueMap::Entry;
using RootEnum = RootedValueMap::Enum;
// For more detail see JS::Rooted::root and js::RootedTraceable.
//
// The JS::RootKind::Traceable list contains a bunch of totally disparate types,
// but to refer to this list we need /something/ in the type field. We use the
// following type as a compatible stand-in. No actual methods from
// ConcreteTraceable type are actually used at runtime.
struct ConcreteTraceable {
ConcreteTraceable() = delete;
void trace(JSTracer*) = delete;
};
template <typename T>
inline void RootedGCThingTraits<T>::trace(JSTracer* trc, T* thingp,
const char* name) {
TraceNullableRoot(trc, thingp, name);
}
template <typename T>
inline void RootedTraceableTraits<T>::trace(JSTracer* trc,
VirtualTraceable* thingp,
const char* name) {
thingp->trace(trc, name);
}
template <typename T>
inline void JS::Rooted<T>::trace(JSTracer* trc, const char* name) {
PtrTraits::trace(trc, &ptr, name);
}
template <typename T>
inline void JS::PersistentRooted<T>::trace(JSTracer* trc, const char* name) {
PtrTraits::trace(trc, &ptr, name);
}
template <typename T>
static inline void TraceExactStackRootList(JSTracer* trc,
JS::Rooted<void*>* listHead,
const char* name) {
auto* typedList = reinterpret_cast<JS::Rooted<T>*>(listHead);
for (JS::Rooted<T>* root = typedList; root; root = root->previous()) {
root->trace(trc, name);
}
}
static inline void TraceStackRoots(JSTracer* trc,
JS::RootedListHeads& stackRoots) {
#define TRACE_ROOTS(name, type, _, _1) \
TraceExactStackRootList<type*>(trc, stackRoots[JS::RootKind::name], \
"exact-" #name);
JS_FOR_EACH_TRACEKIND(TRACE_ROOTS)
#undef TRACE_ROOTS
TraceExactStackRootList<jsid>(trc, stackRoots[JS::RootKind::Id], "exact-id");
TraceExactStackRootList<Value>(trc, stackRoots[JS::RootKind::Value],
"exact-value");
// RootedTraceable uses virtual dispatch.
JS::AutoSuppressGCAnalysis nogc;
TraceExactStackRootList<ConcreteTraceable>(
trc, stackRoots[JS::RootKind::Traceable], "Traceable");
}
void JS::RootingContext::traceStackRoots(JSTracer* trc) {
TraceStackRoots(trc, stackRoots_);
}
static void TraceExactStackRoots(JSContext* cx, JSTracer* trc) {
cx->traceStackRoots(trc);
}
template <typename T>
static inline void TracePersistentRootedList(
JSTracer* trc, LinkedList<PersistentRooted<void*>>& list,
const char* name) {
auto& typedList = reinterpret_cast<LinkedList<PersistentRooted<T>>&>(list);
for (PersistentRooted<T>* root : typedList) {
root->trace(trc, name);
}
}
void JSRuntime::tracePersistentRoots(JSTracer* trc) {
#define TRACE_ROOTS(name, type, _, _1) \
TracePersistentRootedList<type*>(trc, heapRoots.ref()[JS::RootKind::name], \
"persistent-" #name);
JS_FOR_EACH_TRACEKIND(TRACE_ROOTS)
#undef TRACE_ROOTS
TracePersistentRootedList<jsid>(trc, heapRoots.ref()[JS::RootKind::Id],
"persistent-id");
TracePersistentRootedList<Value>(trc, heapRoots.ref()[JS::RootKind::Value],
"persistent-value");
// RootedTraceable uses virtual dispatch.
JS::AutoSuppressGCAnalysis nogc;
TracePersistentRootedList<ConcreteTraceable>(
trc, heapRoots.ref()[JS::RootKind::Traceable], "persistent-traceable");
}
static void TracePersistentRooted(JSRuntime* rt, JSTracer* trc) {
rt->tracePersistentRoots(trc);
}
template <typename T>
static void FinishPersistentRootedChain(
LinkedList<PersistentRooted<void*>>& listArg) {
auto& list = reinterpret_cast<LinkedList<PersistentRooted<T>>&>(listArg);
while (!list.isEmpty()) {
list.getFirst()->reset();
}
}
void JSRuntime::finishPersistentRoots() {
#define FINISH_ROOT_LIST(name, type, _, _1) \
FinishPersistentRootedChain<type*>(heapRoots.ref()[JS::RootKind::name]);
JS_FOR_EACH_TRACEKIND(FINISH_ROOT_LIST)
#undef FINISH_ROOT_LIST
FinishPersistentRootedChain<jsid>(heapRoots.ref()[JS::RootKind::Id]);
FinishPersistentRootedChain<Value>(heapRoots.ref()[JS::RootKind::Value]);
// Note that we do not finalize the Traceable list as we do not know how to
// safely clear members. We instead assert that none escape the RootLists.
// See the comment on RootLists::~RootLists for details.
}
JS_PUBLIC_API void js::TraceValueArray(JSTracer* trc, size_t length,
Value* elements) {
TraceRootRange(trc, length, elements, "JS::RootedValueArray");
}
void AutoGCRooter::trace(JSTracer* trc) {
switch (kind_) {
case Kind::Wrapper:
static_cast<AutoWrapperRooter*>(this)->trace(trc);
break;
case Kind::WrapperVector:
static_cast<AutoWrapperVector*>(this)->trace(trc);
break;
case Kind::Custom:
static_cast<JS::CustomAutoRooter*>(this)->trace(trc);
break;
default:
MOZ_CRASH("Bad AutoGCRooter::Kind");
break;
}
}
void AutoWrapperRooter::trace(JSTracer* trc) {
/*
* We need to use TraceManuallyBarrieredEdge here because we trace wrapper
* roots in every slice. This is because of some rule-breaking in
* RemapAllWrappersForObject; see comment there.
*/
TraceManuallyBarrieredEdge(trc, &value.get(), "js::AutoWrapperRooter.value");
}
void AutoWrapperVector::trace(JSTracer* trc) {
/*
* We need to use TraceManuallyBarrieredEdge here because we trace wrapper
* roots in every slice. This is because of some rule-breaking in
* RemapAllWrappersForObject; see comment there.
*/
for (WrapperValue& value : *this) {
TraceManuallyBarrieredEdge(trc, &value.get(),
"js::AutoWrapperVector.vector");
}
}
void JS::RootingContext::traceAllGCRooters(JSTracer* trc) {
for (AutoGCRooter* list : autoGCRooters_) {
traceGCRooterList(trc, list);
}
}
void JS::RootingContext::traceWrapperGCRooters(JSTracer* trc) {
traceGCRooterList(trc, autoGCRooters_[AutoGCRooter::Kind::Wrapper]);
traceGCRooterList(trc, autoGCRooters_[AutoGCRooter::Kind::WrapperVector]);
}
/* static */
inline void JS::RootingContext::traceGCRooterList(JSTracer* trc,
AutoGCRooter* head) {
for (AutoGCRooter* rooter = head; rooter; rooter = rooter->down) {
rooter->trace(trc);
}
}
void StackShape::trace(JSTracer* trc) {
if (base) {
TraceRoot(trc, &base, "StackShape base");
}
TraceRoot(trc, (jsid*)&propid, "StackShape id");
if ((attrs & JSPROP_GETTER) && rawGetter) {
TraceRoot(trc, (JSObject**)&rawGetter, "StackShape getter");
}
if ((attrs & JSPROP_SETTER) && rawSetter) {
TraceRoot(trc, (JSObject**)&rawSetter, "StackShape setter");
}
}
void PropertyDescriptor::trace(JSTracer* trc) {
if (obj) {
TraceRoot(trc, &obj, "Descriptor::obj");
}
TraceRoot(trc, &value, "Descriptor::value");
if ((attrs & JSPROP_GETTER) && getter) {
JSObject* tmp = JS_FUNC_TO_DATA_PTR(JSObject*, getter);
TraceRoot(trc, &tmp, "Descriptor::get");
getter = JS_DATA_TO_FUNC_PTR(JSGetterOp, tmp);
}
if ((attrs & JSPROP_SETTER) && setter) {
JSObject* tmp = JS_FUNC_TO_DATA_PTR(JSObject*, setter);
TraceRoot(trc, &tmp, "Descriptor::set");
setter = JS_DATA_TO_FUNC_PTR(JSSetterOp, tmp);
}
}
void js::gc::GCRuntime::traceRuntimeForMajorGC(JSTracer* trc,
AutoGCSession& session) {
MOZ_ASSERT(!TlsContext.get()->suppressGC);
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_ROOTS);
if (atomsZone->isCollecting()) {
traceRuntimeAtoms(trc, session.checkAtomsAccess());
}
{
// Trace incoming cross compartment edges from uncollected compartments,
// skipping gray edges which are traced later.
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_CCWS);
Compartment::traceIncomingCrossCompartmentEdgesForZoneGC(
trc, Compartment::NonGrayEdges);
}
markFinalizationRegistryRoots(trc);
traceRuntimeCommon(trc, MarkRuntime);
}
void js::gc::GCRuntime::traceRuntimeForMinorGC(JSTracer* trc,
AutoGCSession& session) {
MOZ_ASSERT(!TlsContext.get()->suppressGC);
// Note that we *must* trace the runtime during the SHUTDOWN_GC's minor GC
// despite having called FinishRoots already. This is because FinishRoots
// does not clear the crossCompartmentWrapper map. It cannot do this
// because Proxy's trace for CrossCompartmentWrappers asserts presence in
// the map. And we can reach its trace function despite having finished the
// roots via the edges stored by the pre-barrier verifier when we finish
// the verifier for the last time.
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_ROOTS);
traceRuntimeCommon(trc, TraceRuntime);
}
void js::TraceRuntime(JSTracer* trc) {
MOZ_ASSERT(!trc->isMarkingTracer());
JSRuntime* rt = trc->runtime();
AutoEmptyNurseryAndPrepareForTracing prep(rt->mainContextFromOwnThread());
gcstats::AutoPhase ap(rt->gc.stats(), gcstats::PhaseKind::TRACE_HEAP);
rt->gc.traceRuntime(trc, prep);
}
void js::TraceRuntimeWithoutEviction(JSTracer* trc) {
MOZ_ASSERT(!trc->isMarkingTracer());
JSRuntime* rt = trc->runtime();
AutoTraceSession session(rt);
gcstats::AutoPhase ap(rt->gc.stats(), gcstats::PhaseKind::TRACE_HEAP);
rt->gc.traceRuntime(trc, session);
}
void js::gc::GCRuntime::traceRuntime(JSTracer* trc, AutoTraceSession& session) {
MOZ_ASSERT(!rt->isBeingDestroyed());
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_ROOTS);
traceRuntimeAtoms(trc, session);
traceRuntimeCommon(trc, TraceRuntime);
}
void js::gc::GCRuntime::traceRuntimeAtoms(JSTracer* trc,
const AutoAccessAtomsZone& access) {
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_RUNTIME_DATA);
rt->tracePermanentAtoms(trc);
TraceAtoms(trc, access);
TraceWellKnownSymbols(trc);
jit::JitRuntime::Trace(trc, access);
}
void js::gc::GCRuntime::traceRuntimeCommon(JSTracer* trc,
TraceOrMarkRuntime traceOrMark) {
{
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_STACK);
JSContext* cx = rt->mainContextFromOwnThread();
// Trace active interpreter and JIT stack roots.
TraceInterpreterActivations(cx, trc);
jit::TraceJitActivations(cx, trc);
// Trace legacy C stack roots.
cx->traceAllGCRooters(trc);
// Trace C stack roots.
TraceExactStackRoots(cx, trc);
for (RootRange r = rootsHash.ref().all(); !r.empty(); r.popFront()) {
const RootEntry& entry = r.front();
TraceRoot(trc, entry.key(), entry.value());
}
}
// Trace runtime global roots.
TracePersistentRooted(rt, trc);
// Trace the self-hosting global compartment.
rt->traceSelfHostingGlobal(trc);
#ifdef JS_HAS_INTL_API
// Trace the shared Intl data.
rt->traceSharedIntlData(trc);
#endif
// Trace the JSContext.
rt->mainContextFromOwnThread()->trace(trc);
// Trace all realm roots, but not the realm itself; it is traced via the
// parent pointer if traceRoots actually traces anything.
for (RealmsIter r(rt); !r.done(); r.next()) {
r->traceRoots(trc, traceOrMark);
}
// Trace zone script-table roots. See comment in
// Zone::traceScriptTableRoots() for justification re: calling this only
// during major (non-nursery) collections.
if (!JS::RuntimeHeapIsMinorCollecting()) {
for (ZonesIter zone(this, ZoneSelector::SkipAtoms); !zone.done();
zone.next()) {
zone->traceScriptTableRoots(trc);
}
}
// Trace helper thread roots.
HelperThreadState().trace(trc);
// Trace Debugger.Frames that have live hooks, since dropping them would be
// observable. In effect, they are rooted by the stack frames.
DebugAPI::traceFramesWithLiveHooks(trc);
// Trace the embedding's black and gray roots.
if (!JS::RuntimeHeapIsMinorCollecting()) {
gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_EMBEDDING);
/*
* The embedding can register additional roots here.
*
* We don't need to trace these in a minor GC because all pointers into
* the nursery should be in the store buffer, and we want to avoid the
* time taken to trace all these roots.
*/
traceEmbeddingBlackRoots(trc);
/* During GC, we don't trace gray roots at this stage. */
if (traceOrMark == TraceRuntime) {
traceEmbeddingGrayRoots(trc);
}
}
traceKeptObjects(trc);
}
void GCRuntime::traceEmbeddingBlackRoots(JSTracer* trc) {
// The analysis doesn't like the function pointer below.
JS::AutoSuppressGCAnalysis nogc;
for (size_t i = 0; i < blackRootTracers.ref().length(); i++) {
const Callback<JSTraceDataOp>& e = blackRootTracers.ref()[i];
(*e.op)(trc, e.data);
}
}
void GCRuntime::traceEmbeddingGrayRoots(JSTracer* trc) {
// The analysis doesn't like the function pointer below.
JS::AutoSuppressGCAnalysis nogc;
const auto& callback = grayRootTracer.ref();
if (JSTraceDataOp op = callback.op) {
(*op)(trc, callback.data);
}
}
#ifdef DEBUG
class AssertNoRootsTracer final : public JS::CallbackTracer {
bool onChild(const JS::GCCellPtr& thing) override {
MOZ_CRASH("There should not be any roots during runtime shutdown");
return true;
}
public:
explicit AssertNoRootsTracer(JSRuntime* rt)
: JS::CallbackTracer(rt, TraceWeakMapKeysValues) {}
};
#endif // DEBUG
void js::gc::GCRuntime::finishRoots() {
AutoNoteSingleThreadedRegion anstr;
rt->finishParserAtoms();
rt->finishAtoms();
rootsHash.ref().clear();
rt->finishPersistentRoots();
rt->finishSelfHosting();
selfHostingZoneFrozen = false;
for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
zone->finishRoots();
}
#ifdef JS_GC_ZEAL
clearSelectedForMarking();
#endif
// Clear any remaining roots from the embedding (as otherwise they will be
// left dangling after we shut down) and remove the callbacks.
ClearEdgesTracer trc(rt);
traceEmbeddingBlackRoots(&trc);
traceEmbeddingGrayRoots(&trc);
clearBlackAndGrayRootTracers();
}
void js::gc::GCRuntime::checkNoRuntimeRoots(AutoGCSession& session) {
#ifdef DEBUG
AssertNoRootsTracer trc(rt);
traceRuntimeForMajorGC(&trc, session);
#endif // DEBUG
}
// Append traced things to a buffer on the zone for use later in the GC.
// See the comment in GCRuntime.h above grayBufferState for details.
class BufferGrayRootsTracer final : public JS::CallbackTracer {
// Set to false if we OOM while buffering gray roots.
bool bufferingGrayRootsFailed;
bool onObjectEdge(JSObject** objp) override { return bufferRoot(*objp); }
bool onStringEdge(JSString** stringp) override {
return bufferRoot(*stringp);
}
bool onScriptEdge(js::BaseScript** scriptp) override {
return bufferRoot(*scriptp);
}
bool onSymbolEdge(JS::Symbol** symbolp) override {
return bufferRoot(*symbolp);
}
bool onBigIntEdge(JS::BigInt** bip) override { return bufferRoot(*bip); }
bool onChild(const JS::GCCellPtr& thing) override {
MOZ_CRASH("Unexpected gray root kind");
return true;
}
template <typename T>
inline bool bufferRoot(T* thing);
public:
explicit BufferGrayRootsTracer(JSRuntime* rt)
: JS::CallbackTracer(rt), bufferingGrayRootsFailed(false) {}
bool failed() const { return bufferingGrayRootsFailed; }
void setFailed() { bufferingGrayRootsFailed = true; }
#ifdef DEBUG
TracerKind getTracerKind() const override {
return TracerKind::GrayBuffering;
}
#endif
};
void js::gc::GCRuntime::bufferGrayRoots() {
// Precondition: the state has been reset to "unused" after the last GC
// and the zone's buffers have been cleared.
MOZ_ASSERT(grayBufferState == GrayBufferState::Unused);
for (GCZonesIter zone(this); !zone.done(); zone.next()) {
MOZ_ASSERT(zone->gcGrayRoots().IsEmpty());
}
BufferGrayRootsTracer grayBufferer(rt);
traceEmbeddingGrayRoots(&grayBufferer);
Compartment::traceIncomingCrossCompartmentEdgesForZoneGC(
&grayBufferer, Compartment::GrayEdges);
// Propagate the failure flag from the marker to the runtime.
if (grayBufferer.failed()) {
grayBufferState = GrayBufferState::Failed;
resetBufferedGrayRoots();
} else {
grayBufferState = GrayBufferState::Okay;
}
}
template <typename T>
inline bool BufferGrayRootsTracer::bufferRoot(T* thing) {
MOZ_ASSERT(JS::RuntimeHeapIsBusy());
MOZ_ASSERT(thing);
// Check if |thing| is corrupt by calling a method that touches the heap.
MOZ_ASSERT(thing->getTraceKind() != JS::TraceKind(0xff));
TenuredCell* tenured = &thing->asTenured();
// This is run from a helper thread while the mutator is paused so we have
// to use *FromAnyThread methods here.
Zone* zone = tenured->zoneFromAnyThread();
if (zone->isCollectingFromAnyThread()) {
// See the comment on SetMaybeAliveFlag to see why we only do this for
// objects and scripts. We rely on gray root buffering for this to work,
// but we only need to worry about uncollected dead compartments during
// incremental GCs (when we do gray root buffering).
SetMaybeAliveFlag(thing);
if (!zone->gcGrayRoots().Append(tenured)) {
bufferingGrayRootsFailed = true;
}
}
return true;
}
void GCRuntime::markBufferedGrayRoots(JS::Zone* zone) {
MOZ_ASSERT(grayBufferState == GrayBufferState::Okay);
MOZ_ASSERT(zone->isGCMarkingBlackAndGray() || zone->isGCCompacting());
auto& roots = zone->gcGrayRoots();
if (roots.IsEmpty()) {
return;
}
for (auto iter = roots.Iter(); !iter.Done(); iter.Next()) {
Cell* cell = iter.Get();
// Bug 1203273: Check for bad pointers on OSX and output diagnostics.
#if defined(XP_DARWIN) && defined(MOZ_DIAGNOSTIC_ASSERT_ENABLED)
auto addr = uintptr_t(cell);
if (addr < ChunkSize || addr % CellAlignBytes != 0) {
MOZ_CRASH_UNSAFE_PRINTF(
"Bad GC thing pointer in gray root buffer: %p at address %p", cell,
&iter.Get());
}
#else
MOZ_ASSERT(IsCellPointerValid(cell));
#endif
TraceManuallyBarrieredGenericPointerEdge(&marker, &cell,
"buffered gray root");
}
}
void GCRuntime::resetBufferedGrayRoots() {
MOZ_ASSERT(
grayBufferState != GrayBufferState::Okay,
"Do not clear the gray buffers unless we are Failed or becoming Unused");
for (GCZonesIter zone(this); !zone.done(); zone.next()) {
zone->gcGrayRoots().Clear();
}
}
JS_PUBLIC_API void JS::AddPersistentRoot(JS::RootingContext* cx, RootKind kind,
PersistentRooted<void*>* root) {
static_cast<JSContext*>(cx)->runtime()->heapRoots.ref()[kind].insertBack(
root);
}
JS_PUBLIC_API void JS::AddPersistentRoot(JSRuntime* rt, RootKind kind,
PersistentRooted<void*>* root) {
rt->heapRoots.ref()[kind].insertBack(root);
}