diff options
Diffstat (limited to 'js/xpconnect/src/XPCJSContext.cpp')
| -rw-r--r-- | js/xpconnect/src/XPCJSContext.cpp | 1451 |
1 files changed, 1451 insertions, 0 deletions
diff --git a/js/xpconnect/src/XPCJSContext.cpp b/js/xpconnect/src/XPCJSContext.cpp new file mode 100644 index 0000000000..7bf574f675 --- /dev/null +++ b/js/xpconnect/src/XPCJSContext.cpp @@ -0,0 +1,1451 @@ +/* -*- 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/. */ + +/* Per JSContext object */ + +#include "mozilla/MemoryReporting.h" +#include "mozilla/UniquePtr.h" + +#include "xpcprivate.h" +#include "xpcpublic.h" +#include "XPCWrapper.h" +#include "XPCJSMemoryReporter.h" +#include "XPCSelfHostedShmem.h" +#include "WrapperFactory.h" +#include "mozJSModuleLoader.h" +#include "nsNetUtil.h" +#include "nsThreadUtils.h" + +#include "nsIObserverService.h" +#include "nsIDebug2.h" +#include "nsPIDOMWindow.h" +#include "nsPrintfCString.h" +#include "mozilla/Preferences.h" +#include "mozilla/Telemetry.h" +#include "mozilla/Services.h" +#ifdef FUZZING +# include "mozilla/StaticPrefs_fuzzing.h" +#endif +#include "mozilla/StaticPrefs_dom.h" +#include "mozilla/StaticPrefs_browser.h" +#include "mozilla/StaticPrefs_javascript.h" +#include "mozilla/dom/ScriptSettings.h" + +#include "nsContentUtils.h" +#include "nsCCUncollectableMarker.h" +#include "nsCycleCollectionNoteRootCallback.h" +#include "nsCycleCollector.h" +#include "nsJSEnvironment.h" +#include "jsapi.h" +#include "js/ArrayBuffer.h" +#include "js/ContextOptions.h" +#include "js/HelperThreadAPI.h" +#include "js/Initialization.h" +#include "js/MemoryMetrics.h" +#include "js/Prefs.h" +#include "js/WasmFeatures.h" +#include "mozilla/dom/BindingUtils.h" +#include "mozilla/dom/ContentChild.h" +#include "mozilla/dom/Document.h" +#include "mozilla/dom/Element.h" +#include "mozilla/dom/ScriptLoader.h" +#include "mozilla/dom/WindowBinding.h" +#include "mozilla/dom/WakeLockBinding.h" +#include "mozilla/extensions/WebExtensionPolicy.h" +#include "mozilla/Atomics.h" +#include "mozilla/Attributes.h" +#include "mozilla/ProcessHangMonitor.h" +#include "mozilla/Sprintf.h" +#include "mozilla/SystemPrincipal.h" +#include "mozilla/TaskController.h" +#include "mozilla/ThreadLocal.h" +#include "mozilla/UniquePtrExtensions.h" +#include "mozilla/Unused.h" +#include "AccessCheck.h" +#include "nsGlobalWindowInner.h" +#include "nsAboutProtocolUtils.h" + +#include "GeckoProfiler.h" +#include "nsIXULRuntime.h" +#include "nsJSPrincipals.h" +#include "ExpandedPrincipal.h" + +#if defined(XP_LINUX) && !defined(ANDROID) +// For getrlimit and min/max. +# include <algorithm> +# include <sys/resource.h> +#endif + +#ifdef XP_WIN +// For min. +# include <algorithm> +# include <windows.h> +#endif + +using namespace mozilla; +using namespace mozilla::dom; +using namespace xpc; +using namespace JS; + +// We will clamp to reasonable values if this isn't set. +#if !defined(PTHREAD_STACK_MIN) +# define PTHREAD_STACK_MIN 0 +#endif + +static void WatchdogMain(void* arg); +class Watchdog; +class WatchdogManager; +class MOZ_RAII AutoLockWatchdog final { + Watchdog* const mWatchdog; + + public: + explicit AutoLockWatchdog(Watchdog* aWatchdog); + ~AutoLockWatchdog(); +}; + +class Watchdog { + public: + explicit Watchdog(WatchdogManager* aManager) + : mManager(aManager), + mLock(nullptr), + mWakeup(nullptr), + mThread(nullptr), + mHibernating(false), + mInitialized(false), + mShuttingDown(false), + mMinScriptRunTimeSeconds(1) {} + ~Watchdog() { MOZ_ASSERT(!Initialized()); } + + WatchdogManager* Manager() { return mManager; } + bool Initialized() { return mInitialized; } + bool ShuttingDown() { return mShuttingDown; } + PRLock* GetLock() { return mLock; } + bool Hibernating() { return mHibernating; } + void WakeUp() { + MOZ_ASSERT(Initialized()); + MOZ_ASSERT(Hibernating()); + mHibernating = false; + PR_NotifyCondVar(mWakeup); + } + + // + // Invoked by the main thread only. + // + + void Init() { + MOZ_ASSERT(NS_IsMainThread()); + mLock = PR_NewLock(); + if (!mLock) { + MOZ_CRASH("PR_NewLock failed."); + } + + mWakeup = PR_NewCondVar(mLock); + if (!mWakeup) { + MOZ_CRASH("PR_NewCondVar failed."); + } + + { + // Make sure the debug service is instantiated before we create the + // watchdog thread, since we intentionally try to keep the thread's stack + // segment as small as possible. It isn't always large enough to + // instantiate a new service, and even when it is, we don't want fault in + // extra pages if we can avoid it. + nsCOMPtr<nsIDebug2> dbg = do_GetService("@mozilla.org/xpcom/debug;1"); + Unused << dbg; + } + + { + AutoLockWatchdog lock(this); + + // The watchdog thread loop is pretty trivial, and should not + // require much stack space to do its job. So only give it 32KiB + // or the platform minimum. On modern Linux libc this might resolve to + // a runtime call. + size_t watchdogStackSize = PTHREAD_STACK_MIN; + watchdogStackSize = std::max<size_t>(32 * 1024, watchdogStackSize); + + // Gecko uses thread private for accounting and has to clean up at thread + // exit. Therefore, even though we don't have a return value from the + // watchdog, we need to join it on shutdown. + mThread = PR_CreateThread(PR_USER_THREAD, WatchdogMain, this, + PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD, + PR_JOINABLE_THREAD, watchdogStackSize); + if (!mThread) { + MOZ_CRASH("PR_CreateThread failed!"); + } + + // WatchdogMain acquires the lock and then asserts mInitialized. So + // make sure to set mInitialized before releasing the lock here so + // that it's atomic with the creation of the thread. + mInitialized = true; + } + } + + void Shutdown() { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(Initialized()); + { // Scoped lock. + AutoLockWatchdog lock(this); + + // Signal to the watchdog thread that it's time to shut down. + mShuttingDown = true; + + // Wake up the watchdog, and wait for it to call us back. + PR_NotifyCondVar(mWakeup); + } + + PR_JoinThread(mThread); + + // The thread sets mShuttingDown to false as it exits. + MOZ_ASSERT(!mShuttingDown); + + // Destroy state. + mThread = nullptr; + PR_DestroyCondVar(mWakeup); + mWakeup = nullptr; + PR_DestroyLock(mLock); + mLock = nullptr; + + // All done. + mInitialized = false; + } + + void SetMinScriptRunTimeSeconds(int32_t seconds) { + // This variable is atomic, and is set from the main thread without + // locking. + MOZ_ASSERT(seconds > 0); + mMinScriptRunTimeSeconds = seconds; + } + + // + // Invoked by the watchdog thread only. + // + + void Hibernate() { + MOZ_ASSERT(!NS_IsMainThread()); + mHibernating = true; + Sleep(PR_INTERVAL_NO_TIMEOUT); + } + void Sleep(PRIntervalTime timeout) { + MOZ_ASSERT(!NS_IsMainThread()); + AUTO_PROFILER_THREAD_SLEEP; + MOZ_ALWAYS_TRUE(PR_WaitCondVar(mWakeup, timeout) == PR_SUCCESS); + } + void Finished() { + MOZ_ASSERT(!NS_IsMainThread()); + mShuttingDown = false; + } + + int32_t MinScriptRunTimeSeconds() { return mMinScriptRunTimeSeconds; } + + private: + WatchdogManager* mManager; + + PRLock* mLock; + PRCondVar* mWakeup; + PRThread* mThread; + bool mHibernating; + bool mInitialized; + bool mShuttingDown; + mozilla::Atomic<int32_t> mMinScriptRunTimeSeconds; +}; + +#define PREF_MAX_SCRIPT_RUN_TIME_CONTENT "dom.max_script_run_time" +#define PREF_MAX_SCRIPT_RUN_TIME_CHROME "dom.max_chrome_script_run_time" +#define PREF_MAX_SCRIPT_RUN_TIME_EXT_CONTENT \ + "dom.max_ext_content_script_run_time" + +static const char* gCallbackPrefs[] = { + "dom.use_watchdog", + PREF_MAX_SCRIPT_RUN_TIME_CONTENT, + PREF_MAX_SCRIPT_RUN_TIME_CHROME, + PREF_MAX_SCRIPT_RUN_TIME_EXT_CONTENT, + nullptr, +}; + +class WatchdogManager { + public: + explicit WatchdogManager() { + // All the timestamps start at zero. + PodArrayZero(mTimestamps); + + // Register ourselves as an observer to get updates on the pref. + Preferences::RegisterCallbacks(PrefsChanged, gCallbackPrefs, this); + } + + virtual ~WatchdogManager() { + // Shutting down the watchdog requires context-switching to the watchdog + // thread, which isn't great to do in a destructor. So we require + // consumers to shut it down manually before releasing it. + MOZ_ASSERT(!mWatchdog); + } + + private: + static void PrefsChanged(const char* aPref, void* aSelf) { + static_cast<WatchdogManager*>(aSelf)->RefreshWatchdog(); + } + + public: + void Shutdown() { + Preferences::UnregisterCallbacks(PrefsChanged, gCallbackPrefs, this); + } + + void RegisterContext(XPCJSContext* aContext) { + MOZ_ASSERT(NS_IsMainThread()); + AutoLockWatchdog lock(mWatchdog.get()); + + if (aContext->mActive == XPCJSContext::CONTEXT_ACTIVE) { + mActiveContexts.insertBack(aContext); + } else { + mInactiveContexts.insertBack(aContext); + } + + // Enable the watchdog, if appropriate. + RefreshWatchdog(); + } + + void UnregisterContext(XPCJSContext* aContext) { + MOZ_ASSERT(NS_IsMainThread()); + AutoLockWatchdog lock(mWatchdog.get()); + + // aContext must be in one of our two lists, simply remove it. + aContext->LinkedListElement<XPCJSContext>::remove(); + +#ifdef DEBUG + // If this was the last context, we should have already shut down + // the watchdog. + if (mActiveContexts.isEmpty() && mInactiveContexts.isEmpty()) { + MOZ_ASSERT(!mWatchdog); + } +#endif + } + + // Context statistics. These live on the watchdog manager, are written + // from the main thread, and are read from the watchdog thread (holding + // the lock in each case). + void RecordContextActivity(XPCJSContext* aContext, bool active) { + // The watchdog reads this state, so acquire the lock before writing it. + MOZ_ASSERT(NS_IsMainThread()); + AutoLockWatchdog lock(mWatchdog.get()); + + // Write state. + aContext->mLastStateChange = PR_Now(); + aContext->mActive = + active ? XPCJSContext::CONTEXT_ACTIVE : XPCJSContext::CONTEXT_INACTIVE; + UpdateContextLists(aContext); + + // The watchdog may be hibernating, waiting for the context to go + // active. Wake it up if necessary. + if (active && mWatchdog && mWatchdog->Hibernating()) { + mWatchdog->WakeUp(); + } + } + + bool IsAnyContextActive() { return !mActiveContexts.isEmpty(); } + PRTime TimeSinceLastActiveContext() { + // Must be called on the watchdog thread with the lock held. + MOZ_ASSERT(!NS_IsMainThread()); + PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mWatchdog->GetLock()); + MOZ_ASSERT(mActiveContexts.isEmpty()); + MOZ_ASSERT(!mInactiveContexts.isEmpty()); + + // We store inactive contexts with the most recently added inactive + // context at the end of the list. + return PR_Now() - mInactiveContexts.getLast()->mLastStateChange; + } + + void RecordTimestamp(WatchdogTimestampCategory aCategory) { + // Must be called on the watchdog thread with the lock held. + MOZ_ASSERT(!NS_IsMainThread()); + PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mWatchdog->GetLock()); + MOZ_ASSERT(aCategory != TimestampContextStateChange, + "Use RecordContextActivity to update this"); + + mTimestamps[aCategory] = PR_Now(); + } + + PRTime GetContextTimestamp(XPCJSContext* aContext, + const AutoLockWatchdog& aProofOfLock) { + return aContext->mLastStateChange; + } + + PRTime GetTimestamp(WatchdogTimestampCategory aCategory, + const AutoLockWatchdog& aProofOfLock) { + MOZ_ASSERT(aCategory != TimestampContextStateChange, + "Use GetContextTimestamp to retrieve this"); + return mTimestamps[aCategory]; + } + + Watchdog* GetWatchdog() { return mWatchdog.get(); } + + void RefreshWatchdog() { + bool wantWatchdog = Preferences::GetBool("dom.use_watchdog", true); + if (wantWatchdog != !!mWatchdog) { + if (wantWatchdog) { + StartWatchdog(); + } else { + StopWatchdog(); + } + } + + if (mWatchdog) { + int32_t contentTime = StaticPrefs::dom_max_script_run_time(); + if (contentTime <= 0) { + contentTime = INT32_MAX; + } + int32_t chromeTime = StaticPrefs::dom_max_chrome_script_run_time(); + if (chromeTime <= 0) { + chromeTime = INT32_MAX; + } + int32_t extTime = StaticPrefs::dom_max_ext_content_script_run_time(); + if (extTime <= 0) { + extTime = INT32_MAX; + } + mWatchdog->SetMinScriptRunTimeSeconds( + std::min({contentTime, chromeTime, extTime})); + } + } + + void StartWatchdog() { + MOZ_ASSERT(!mWatchdog); + mWatchdog = mozilla::MakeUnique<Watchdog>(this); + mWatchdog->Init(); + } + + void StopWatchdog() { + MOZ_ASSERT(mWatchdog); + mWatchdog->Shutdown(); + mWatchdog = nullptr; + } + + template <class Callback> + void ForAllActiveContexts(Callback&& aCallback) { + // This function must be called on the watchdog thread with the lock held. + MOZ_ASSERT(!NS_IsMainThread()); + PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mWatchdog->GetLock()); + + for (auto* context = mActiveContexts.getFirst(); context; + context = context->LinkedListElement<XPCJSContext>::getNext()) { + if (!aCallback(context)) { + return; + } + } + } + + private: + void UpdateContextLists(XPCJSContext* aContext) { + // Given aContext whose activity state or timestamp has just changed, + // put it back in the proper position in the proper list. + aContext->LinkedListElement<XPCJSContext>::remove(); + auto& list = aContext->mActive == XPCJSContext::CONTEXT_ACTIVE + ? mActiveContexts + : mInactiveContexts; + + // Either the new list is empty or aContext must be more recent than + // the existing last element. + MOZ_ASSERT_IF(!list.isEmpty(), list.getLast()->mLastStateChange < + aContext->mLastStateChange); + list.insertBack(aContext); + } + + LinkedList<XPCJSContext> mActiveContexts; + LinkedList<XPCJSContext> mInactiveContexts; + mozilla::UniquePtr<Watchdog> mWatchdog; + + // We store ContextStateChange on the contexts themselves. + PRTime mTimestamps[kWatchdogTimestampCategoryCount - 1]; +}; + +AutoLockWatchdog::AutoLockWatchdog(Watchdog* aWatchdog) : mWatchdog(aWatchdog) { + if (mWatchdog) { + PR_Lock(mWatchdog->GetLock()); + } +} + +AutoLockWatchdog::~AutoLockWatchdog() { + if (mWatchdog) { + PR_Unlock(mWatchdog->GetLock()); + } +} + +static void WatchdogMain(void* arg) { + AUTO_PROFILER_REGISTER_THREAD("JS Watchdog"); + // Create an nsThread wrapper for the thread and register it with the thread + // manager. + Unused << NS_GetCurrentThread(); + NS_SetCurrentThreadName("JS Watchdog"); + + Watchdog* self = static_cast<Watchdog*>(arg); + WatchdogManager* manager = self->Manager(); + + // Lock lasts until we return + AutoLockWatchdog lock(self); + + MOZ_ASSERT(self->Initialized()); + while (!self->ShuttingDown()) { + // Sleep only 1 second if recently (or currently) active; otherwise, + // hibernate + if (manager->IsAnyContextActive() || + manager->TimeSinceLastActiveContext() <= PRTime(2 * PR_USEC_PER_SEC)) { + self->Sleep(PR_TicksPerSecond()); + } else { + manager->RecordTimestamp(TimestampWatchdogHibernateStart); + self->Hibernate(); + manager->RecordTimestamp(TimestampWatchdogHibernateStop); + } + + // Rise and shine. + manager->RecordTimestamp(TimestampWatchdogWakeup); + + // Don't request an interrupt callback unless the current script has + // been running long enough that we might show the slow script dialog. + // Triggering the callback from off the main thread can be expensive. + + // We want to avoid showing the slow script dialog if the user's laptop + // goes to sleep in the middle of running a script. To ensure this, we + // invoke the interrupt callback after only half the timeout has + // elapsed. The callback simply records the fact that it was called in + // the mSlowScriptSecondHalf flag. Then we wait another (timeout/2) + // seconds and invoke the callback again. This time around it sees + // mSlowScriptSecondHalf is set and so it shows the slow script + // dialog. If the computer is put to sleep during one of the (timeout/2) + // periods, the script still has the other (timeout/2) seconds to + // finish. + if (!self->ShuttingDown() && manager->IsAnyContextActive()) { + bool debuggerAttached = false; + nsCOMPtr<nsIDebug2> dbg = do_GetService("@mozilla.org/xpcom/debug;1"); + if (dbg) { + dbg->GetIsDebuggerAttached(&debuggerAttached); + } + if (debuggerAttached) { + // We won't be interrupting these scripts anyway. + continue; + } + + PRTime usecs = self->MinScriptRunTimeSeconds() * PR_USEC_PER_SEC / 2; + manager->ForAllActiveContexts([usecs, manager, + &lock](XPCJSContext* aContext) -> bool { + auto timediff = PR_Now() - manager->GetContextTimestamp(aContext, lock); + if (timediff > usecs) { + JS_RequestInterruptCallback(aContext->Context()); + return true; + } + return false; + }); + } + } + + // Tell the manager that we've shut down. + self->Finished(); +} + +PRTime XPCJSContext::GetWatchdogTimestamp(WatchdogTimestampCategory aCategory) { + AutoLockWatchdog lock(mWatchdogManager->GetWatchdog()); + return aCategory == TimestampContextStateChange + ? mWatchdogManager->GetContextTimestamp(this, lock) + : mWatchdogManager->GetTimestamp(aCategory, lock); +} + +// static +bool XPCJSContext::RecordScriptActivity(bool aActive) { + MOZ_ASSERT(NS_IsMainThread()); + + XPCJSContext* xpccx = XPCJSContext::Get(); + if (!xpccx) { + // mozilla::SpinEventLoopUntil may use AutoScriptActivity(false) after + // we destroyed the XPCJSContext. + MOZ_ASSERT(!aActive); + return false; + } + + bool oldValue = xpccx->SetHasScriptActivity(aActive); + if (aActive == oldValue) { + // Nothing to do. + return oldValue; + } + + if (!aActive) { + ProcessHangMonitor::ClearHang(); + } + xpccx->mWatchdogManager->RecordContextActivity(xpccx, aActive); + + return oldValue; +} + +AutoScriptActivity::AutoScriptActivity(bool aActive) + : mActive(aActive), + mOldValue(XPCJSContext::RecordScriptActivity(aActive)) {} + +AutoScriptActivity::~AutoScriptActivity() { + MOZ_ALWAYS_TRUE(mActive == XPCJSContext::RecordScriptActivity(mOldValue)); +} + +static const double sChromeSlowScriptTelemetryCutoff(10.0); +static bool sTelemetryEventEnabled(false); + +// static +bool XPCJSContext::InterruptCallback(JSContext* cx) { + XPCJSContext* self = XPCJSContext::Get(); + + // Now is a good time to turn on profiling if it's pending. + PROFILER_JS_INTERRUPT_CALLBACK(); + + if (profiler_thread_is_being_profiled_for_markers()) { + nsDependentCString filename("unknown file"); + JS::AutoFilename scriptFilename; + // Computing the line number can be very expensive (see bug 1330231 for + // example), so don't request it here. + if (JS::DescribeScriptedCaller(cx, &scriptFilename)) { + if (const char* file = scriptFilename.get()) { + filename.Assign(file, strlen(file)); + } + PROFILER_MARKER_TEXT("JS::InterruptCallback", JS, {}, filename); + } + } + + // Normally we record mSlowScriptCheckpoint when we start to process an + // event. However, we can run JS outside of event handlers. This code takes + // care of that case. + if (self->mSlowScriptCheckpoint.IsNull()) { + self->mSlowScriptCheckpoint = TimeStamp::NowLoRes(); + self->mSlowScriptSecondHalf = false; + self->mSlowScriptActualWait = mozilla::TimeDuration(); + self->mTimeoutAccumulated = false; + self->mExecutedChromeScript = false; + return true; + } + + // Sometimes we get called back during XPConnect initialization, before Gecko + // has finished bootstrapping. Avoid crashing in nsContentUtils below. + if (!nsContentUtils::IsInitialized()) { + return true; + } + + // This is at least the second interrupt callback we've received since + // returning to the event loop. See how long it's been, and what the limit + // is. + TimeStamp now = TimeStamp::NowLoRes(); + TimeDuration duration = now - self->mSlowScriptCheckpoint; + int32_t limit; + + nsString addonId; + const char* prefName; + auto principal = BasePrincipal::Cast(nsContentUtils::SubjectPrincipal(cx)); + bool chrome = principal->Is<SystemPrincipal>(); + if (chrome) { + prefName = PREF_MAX_SCRIPT_RUN_TIME_CHROME; + limit = StaticPrefs::dom_max_chrome_script_run_time(); + self->mExecutedChromeScript = true; + } else if (auto policy = principal->ContentScriptAddonPolicy()) { + policy->GetId(addonId); + prefName = PREF_MAX_SCRIPT_RUN_TIME_EXT_CONTENT; + limit = StaticPrefs::dom_max_ext_content_script_run_time(); + } else { + prefName = PREF_MAX_SCRIPT_RUN_TIME_CONTENT; + limit = StaticPrefs::dom_max_script_run_time(); + } + + // When the parent process slow script dialog is disabled, we still want + // to be able to track things for telemetry, so set `mSlowScriptSecondHalf` + // to true in that case: + if (limit == 0 && chrome && + duration.ToSeconds() > sChromeSlowScriptTelemetryCutoff / 2.0) { + self->mSlowScriptSecondHalf = true; + return true; + } + // If there's no limit, or we're within the limit, let it go. + if (limit == 0 || duration.ToSeconds() < limit / 2.0) { + return true; + } + + self->mSlowScriptCheckpoint = now; + self->mSlowScriptActualWait += duration; + + // In order to guard against time changes or laptops going to sleep, we + // don't trigger the slow script warning until (limit/2) seconds have + // elapsed twice. + if (!self->mSlowScriptSecondHalf) { + self->mSlowScriptSecondHalf = true; + return true; + } + + // For scripts in content processes, we only want to show the slow script + // dialogue if the user is actually trying to perform an important + // interaction. In theory this could be a chrome script running in the + // content process, which we probably don't want to give the user the ability + // to terminate. However, if this is the case we won't be able to map the + // script global to a window and we'll bail out below. + if (XRE_IsContentProcess() && + StaticPrefs::dom_max_script_run_time_require_critical_input()) { + // Call possibly slow PeekMessages after the other common early returns in + // this method. + ContentChild* contentChild = ContentChild::GetSingleton(); + mozilla::ipc::MessageChannel* channel = + contentChild ? contentChild->GetIPCChannel() : nullptr; + if (channel) { + bool foundInputEvent = false; + channel->PeekMessages( + [&foundInputEvent](const IPC::Message& aMsg) -> bool { + if (nsContentUtils::IsMessageCriticalInputEvent(aMsg)) { + foundInputEvent = true; + return false; + } + return true; + }); + if (!foundInputEvent) { + return true; + } + } + } + + // We use a fixed value of 2 from browser_parent_process_hang_telemetry.js + // to check if the telemetry events work. Do not interrupt it with a dialog. + if (chrome && limit == 2 && xpc::IsInAutomation()) { + return true; + } + + // + // This has gone on long enough! Time to take action. ;-) + // + + // Get the DOM window associated with the running script. If the script is + // running in a non-DOM scope, we have to just let it keep running. + RootedObject global(cx, JS::CurrentGlobalOrNull(cx)); + RefPtr<nsGlobalWindowInner> win = WindowOrNull(global); + if (!win) { + // If this is a sandbox associated with a DOMWindow via a + // sandboxPrototype, use that DOMWindow. This supports WebExtension + // content scripts. + win = SandboxWindowOrNull(global, cx); + } + + if (!win) { + NS_WARNING("No active window"); + return true; + } + + if (win->IsDying()) { + // The window is being torn down. When that happens we try to prevent + // the dispatch of new runnables, so it also makes sense to kill any + // long-running script. The user is primarily interested in this page + // going away. + return false; + } + + // Accumulate slow script invokation delay. + if (!chrome && !self->mTimeoutAccumulated) { + uint32_t delay = uint32_t(self->mSlowScriptActualWait.ToMilliseconds() - + (limit * 1000.0)); + Telemetry::Accumulate(Telemetry::SLOW_SCRIPT_NOTIFY_DELAY, delay); + self->mTimeoutAccumulated = true; + } + + // Show the prompt to the user, and kill if requested. + nsGlobalWindowInner::SlowScriptResponse response = win->ShowSlowScriptDialog( + cx, addonId, self->mSlowScriptActualWait.ToMilliseconds()); + if (response == nsGlobalWindowInner::KillSlowScript) { + if (Preferences::GetBool("dom.global_stop_script", true)) { + xpc::Scriptability::Get(global).Block(); + } + if (nsCOMPtr<Document> doc = win->GetExtantDoc()) { + doc->UnlockAllWakeLocks(WakeLockType::Screen); + } + return false; + } + + // The user chose to continue the script. Reset the timer, and disable this + // machinery with a pref if the user opted out of future slow-script dialogs. + if (response != nsGlobalWindowInner::ContinueSlowScriptAndKeepNotifying) { + self->mSlowScriptCheckpoint = TimeStamp::NowLoRes(); + } + + if (response == nsGlobalWindowInner::AlwaysContinueSlowScript) { + Preferences::SetInt(prefName, 0); + } + + return true; +} + +#define JS_OPTIONS_DOT_STR "javascript.options." + +static mozilla::Atomic<bool> sDiscardSystemSource(false); + +bool xpc::ShouldDiscardSystemSource() { return sDiscardSystemSource; } + +static mozilla::Atomic<bool> sSharedMemoryEnabled(false); +static mozilla::Atomic<bool> sStreamsEnabled(false); + +void xpc::SetPrefableRealmOptions(JS::RealmOptions& options) { + options.creationOptions() + .setSharedMemoryAndAtomicsEnabled(sSharedMemoryEnabled) + .setCoopAndCoepEnabled( + StaticPrefs::browser_tabs_remote_useCrossOriginOpenerPolicy() && + StaticPrefs::browser_tabs_remote_useCrossOriginEmbedderPolicy()); +} + +void xpc::SetPrefableCompileOptions(JS::PrefableCompileOptions& options) { + options + .setSourcePragmas(StaticPrefs::javascript_options_source_pragmas()) +#ifdef NIGHTLY_BUILD + .setImportAttributes( + StaticPrefs::javascript_options_experimental_import_attributes()) + .setImportAttributesAssertSyntax( + StaticPrefs:: + javascript_options_experimental_import_attributes_assert_syntax()) +#endif + .setAsmJS(StaticPrefs::javascript_options_asmjs()) + .setThrowOnAsmJSValidationFailure( + StaticPrefs::javascript_options_throw_on_asmjs_validation_failure()); +} + +void xpc::SetPrefableContextOptions(JS::ContextOptions& options) { + options +#ifdef FUZZING + .setFuzzing(Preferences::GetBool(JS_OPTIONS_DOT_STR "fuzzing.enabled")) +#endif + .setWasm(Preferences::GetBool(JS_OPTIONS_DOT_STR "wasm")) + .setWasmForTrustedPrinciples( + Preferences::GetBool(JS_OPTIONS_DOT_STR "wasm_trustedprincipals")) + .setWasmIon(Preferences::GetBool(JS_OPTIONS_DOT_STR "wasm_optimizingjit")) + .setWasmBaseline( + Preferences::GetBool(JS_OPTIONS_DOT_STR "wasm_baselinejit")) +#define WASM_FEATURE(NAME, LOWER_NAME, STAGE, COMPILE_PRED, COMPILER_PRED, \ + FLAG_PRED, FLAG_FORCE_ON, FLAG_FUZZ_ON, SHELL, PREF) \ + .setWasm##NAME(Preferences::GetBool(JS_OPTIONS_DOT_STR "wasm_" PREF)) + JS_FOR_WASM_FEATURES(WASM_FEATURE) +#undef WASM_FEATURE + .setWasmVerbose(Preferences::GetBool(JS_OPTIONS_DOT_STR "wasm_verbose")) + .setAsyncStack(Preferences::GetBool(JS_OPTIONS_DOT_STR "asyncstack")) + .setAsyncStackCaptureDebuggeeOnly(Preferences::GetBool( + JS_OPTIONS_DOT_STR "asyncstack_capture_debuggee_only")); + + SetPrefableCompileOptions(options.compileOptions()); +} + +// Mirrored value of javascript.options.self_hosted.use_shared_memory. +static bool sSelfHostedUseSharedMemory = false; + +static void LoadStartupJSPrefs(XPCJSContext* xpccx) { + // Prefs that require a restart are handled here. This includes the + // process-wide JIT options because toggling these at runtime can easily cause + // races or get us into an inconsistent state. + // + // 'Live' prefs are handled by ReloadPrefsCallback below. + + // Note: JS::Prefs are set earlier in startup, in InitializeJS in + // XPCOMInit.cpp. + + JSContext* cx = xpccx->Context(); + + // Some prefs are unlisted in all.js / StaticPrefs (and thus are invisible in + // about:config). Make sure we use explicit defaults here. + bool useJitForTrustedPrincipals = + Preferences::GetBool(JS_OPTIONS_DOT_STR "jit_trustedprincipals", false); + bool disableWasmHugeMemory = Preferences::GetBool( + JS_OPTIONS_DOT_STR "wasm_disable_huge_memory", false); + + bool safeMode = false; + nsCOMPtr<nsIXULRuntime> xr = do_GetService("@mozilla.org/xre/runtime;1"); + if (xr) { + xr->GetInSafeMode(&safeMode); + } + + // NOTE: Baseline Interpreter is still used in safe-mode. This gives a big + // perf gain and is our simplest JIT so we make a tradeoff. + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_BASELINE_INTERPRETER_ENABLE, + StaticPrefs::javascript_options_blinterp_DoNotUseDirectly()); + + // Disable most JITs in Safe-Mode. + if (safeMode) { + JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_BASELINE_ENABLE, false); + JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_ION_ENABLE, false); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_JIT_TRUSTEDPRINCIPALS_ENABLE, false); + JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_NATIVE_REGEXP_ENABLE, + false); + JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_JIT_HINTS_ENABLE, false); + sSelfHostedUseSharedMemory = false; + } else { + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_BASELINE_ENABLE, + StaticPrefs::javascript_options_baselinejit_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_ION_ENABLE, + StaticPrefs::javascript_options_ion_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption(cx, + JSJITCOMPILER_JIT_TRUSTEDPRINCIPALS_ENABLE, + useJitForTrustedPrincipals); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_NATIVE_REGEXP_ENABLE, + StaticPrefs::javascript_options_native_regexp_DoNotUseDirectly()); + // Only enable the jit hints cache for the content process to avoid + // any possible jank or delays on the parent process. + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_JIT_HINTS_ENABLE, + XRE_IsContentProcess() + ? StaticPrefs::javascript_options_jithints_DoNotUseDirectly() + : false); + sSelfHostedUseSharedMemory = StaticPrefs:: + javascript_options_self_hosted_use_shared_memory_DoNotUseDirectly(); + } + + JS_SetOffthreadIonCompilationEnabled( + cx, StaticPrefs:: + javascript_options_ion_offthread_compilation_DoNotUseDirectly()); + + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_BASELINE_INTERPRETER_WARMUP_TRIGGER, + StaticPrefs::javascript_options_blinterp_threshold_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_BASELINE_WARMUP_TRIGGER, + StaticPrefs::javascript_options_baselinejit_threshold_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_ION_NORMAL_WARMUP_TRIGGER, + StaticPrefs::javascript_options_ion_threshold_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_ION_FREQUENT_BAILOUT_THRESHOLD, + StaticPrefs:: + javascript_options_ion_frequent_bailout_threshold_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_INLINING_BYTECODE_MAX_LENGTH, + StaticPrefs:: + javascript_options_inlining_bytecode_max_length_DoNotUseDirectly()); + +#ifdef DEBUG + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_FULL_DEBUG_CHECKS, + StaticPrefs::javascript_options_jit_full_debug_checks_DoNotUseDirectly()); +#endif + +#if !defined(JS_CODEGEN_MIPS32) && !defined(JS_CODEGEN_MIPS64) && \ + !defined(JS_CODEGEN_RISCV64) && !defined(JS_CODEGEN_LOONG64) + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_SPECTRE_INDEX_MASKING, + StaticPrefs::javascript_options_spectre_index_masking_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_SPECTRE_OBJECT_MITIGATIONS, + StaticPrefs:: + javascript_options_spectre_object_mitigations_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_SPECTRE_STRING_MITIGATIONS, + StaticPrefs:: + javascript_options_spectre_string_mitigations_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_SPECTRE_VALUE_MASKING, + StaticPrefs::javascript_options_spectre_value_masking_DoNotUseDirectly()); + JS_SetGlobalJitCompilerOption( + cx, JSJITCOMPILER_SPECTRE_JIT_TO_CXX_CALLS, + StaticPrefs:: + javascript_options_spectre_jit_to_cxx_calls_DoNotUseDirectly()); +#endif + + bool writeProtectCode = true; + if (XRE_IsContentProcess()) { + writeProtectCode = + StaticPrefs::javascript_options_content_process_write_protect_code(); + } + JS_SetGlobalJitCompilerOption(cx, JSJITCOMPILER_WRITE_PROTECT_CODE, + writeProtectCode); + + if (disableWasmHugeMemory) { + bool disabledHugeMemory = JS::DisableWasmHugeMemory(); + MOZ_RELEASE_ASSERT(disabledHugeMemory); + } +} + +static void ReloadPrefsCallback(const char* pref, void* aXpccx) { + // Note: Prefs that require a restart are handled in LoadStartupJSPrefs above. + + // Update all non-startup JS::Prefs. + SET_NON_STARTUP_JS_PREFS_FROM_BROWSER_PREFS; + + auto xpccx = static_cast<XPCJSContext*>(aXpccx); + JSContext* cx = xpccx->Context(); + + sDiscardSystemSource = + Preferences::GetBool(JS_OPTIONS_DOT_STR "discardSystemSource"); + sSharedMemoryEnabled = + Preferences::GetBool(JS_OPTIONS_DOT_STR "shared_memory"); + sStreamsEnabled = Preferences::GetBool(JS_OPTIONS_DOT_STR "streams"); + +#ifdef JS_GC_ZEAL + int32_t zeal = Preferences::GetInt(JS_OPTIONS_DOT_STR "gczeal", -1); + int32_t zeal_frequency = Preferences::GetInt( + JS_OPTIONS_DOT_STR "gczeal.frequency", JS_DEFAULT_ZEAL_FREQ); + if (zeal >= 0) { + JS_SetGCZeal(cx, (uint8_t)zeal, zeal_frequency); + } +#endif // JS_GC_ZEAL + + auto& contextOptions = JS::ContextOptionsRef(cx); + SetPrefableContextOptions(contextOptions); + + // Set options not shared with workers. + contextOptions + .setThrowOnDebuggeeWouldRun(Preferences::GetBool( + JS_OPTIONS_DOT_STR "throw_on_debuggee_would_run")) + .setDumpStackOnDebuggeeWouldRun(Preferences::GetBool( + JS_OPTIONS_DOT_STR "dump_stack_on_debuggee_would_run")); + + nsCOMPtr<nsIXULRuntime> xr = do_GetService("@mozilla.org/xre/runtime;1"); + if (xr) { + bool safeMode = false; + xr->GetInSafeMode(&safeMode); + if (safeMode) { + contextOptions.disableOptionsForSafeMode(); + } + } + + JS_SetParallelParsingEnabled( + cx, StaticPrefs::javascript_options_parallel_parsing()); +} + +XPCJSContext::~XPCJSContext() { + MOZ_COUNT_DTOR_INHERITED(XPCJSContext, CycleCollectedJSContext); + // Elsewhere we abort immediately if XPCJSContext initialization fails. + // Therefore the context must be non-null. + MOZ_ASSERT(MaybeContext()); + + Preferences::UnregisterPrefixCallback(ReloadPrefsCallback, JS_OPTIONS_DOT_STR, + this); + +#ifdef FUZZING + Preferences::UnregisterCallback(ReloadPrefsCallback, "fuzzing.enabled", this); +#endif + + // Clear any pending exception. It might be an XPCWrappedJS, and if we try + // to destroy it later we will crash. + SetPendingException(nullptr); + + // If we're the last XPCJSContext around, clean up the watchdog manager. + if (--sInstanceCount == 0) { + if (mWatchdogManager->GetWatchdog()) { + mWatchdogManager->StopWatchdog(); + } + + mWatchdogManager->UnregisterContext(this); + mWatchdogManager->Shutdown(); + sWatchdogInstance = nullptr; + } else { + // Otherwise, simply remove ourselves from the list. + mWatchdogManager->UnregisterContext(this); + } + + if (mCallContext) { + mCallContext->SystemIsBeingShutDown(); + } + + PROFILER_CLEAR_JS_CONTEXT(); +} + +XPCJSContext::XPCJSContext() + : mCallContext(nullptr), + mAutoRoots(nullptr), + mResolveName(JS::PropertyKey::Void()), + mResolvingWrapper(nullptr), + mWatchdogManager(GetWatchdogManager()), + mSlowScriptSecondHalf(false), + mTimeoutAccumulated(false), + mExecutedChromeScript(false), + mHasScriptActivity(false), + mPendingResult(NS_OK), + mActive(CONTEXT_INACTIVE), + mLastStateChange(PR_Now()) { + MOZ_COUNT_CTOR_INHERITED(XPCJSContext, CycleCollectedJSContext); + MOZ_ASSERT(mWatchdogManager); + ++sInstanceCount; + mWatchdogManager->RegisterContext(this); +} + +/* static */ +XPCJSContext* XPCJSContext::Get() { + // Do an explicit null check, because this can get called from a process that + // does not run JS. + nsXPConnect* xpc = static_cast<nsXPConnect*>(nsXPConnect::XPConnect()); + return xpc ? xpc->GetContext() : nullptr; +} + +#ifdef XP_WIN +static size_t GetWindowsStackSize() { + // First, get the stack base. Because the stack grows down, this is the top + // of the stack. + const uint8_t* stackTop; +# ifdef _WIN64 + PNT_TIB64 pTib = reinterpret_cast<PNT_TIB64>(NtCurrentTeb()); + stackTop = reinterpret_cast<const uint8_t*>(pTib->StackBase); +# else + PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb()); + stackTop = reinterpret_cast<const uint8_t*>(pTib->StackBase); +# endif + + // Now determine the stack bottom. Note that we can't use tib->StackLimit, + // because that's the size of the committed area and we're also interested + // in the reserved pages below that. + MEMORY_BASIC_INFORMATION mbi; + if (!VirtualQuery(&mbi, &mbi, sizeof(mbi))) { + MOZ_CRASH("VirtualQuery failed"); + } + + const uint8_t* stackBottom = + reinterpret_cast<const uint8_t*>(mbi.AllocationBase); + + // Do some sanity checks. + size_t stackSize = size_t(stackTop - stackBottom); + MOZ_RELEASE_ASSERT(stackSize >= 1 * 1024 * 1024); + MOZ_RELEASE_ASSERT(stackSize <= 32 * 1024 * 1024); + + // Subtract 40 KB (Win32) or 80 KB (Win64) to account for things like + // the guard page and large PGO stack frames. + return stackSize - 10 * sizeof(uintptr_t) * 1024; +} +#endif + +XPCJSRuntime* XPCJSContext::Runtime() const { + return static_cast<XPCJSRuntime*>(CycleCollectedJSContext::Runtime()); +} + +CycleCollectedJSRuntime* XPCJSContext::CreateRuntime(JSContext* aCx) { + return new XPCJSRuntime(aCx); +} + +class HelperThreadTaskHandler : public Task { + public: + TaskResult Run() override { + JS::RunHelperThreadTask(); + return TaskResult::Complete; + } + explicit HelperThreadTaskHandler() + : Task(Kind::OffMainThreadOnly, EventQueuePriority::Normal) { + // Bug 1703185: Currently all tasks are run at the same priority. + } + +#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY + bool GetName(nsACString& aName) override { + aName.AssignLiteral("HelperThreadTask"); + return true; + } +#endif + + private: + ~HelperThreadTaskHandler() = default; +}; + +static void DispatchOffThreadTask(JS::DispatchReason) { + TaskController::Get()->AddTask(MakeAndAddRef<HelperThreadTaskHandler>()); +} + +static bool CreateSelfHostedSharedMemory(JSContext* aCx, + JS::SelfHostedCache aBuf) { + auto& shm = xpc::SelfHostedShmem::GetSingleton(); + MOZ_RELEASE_ASSERT(shm.Content().IsEmpty()); + // Failures within InitFromParent output warnings but do not cause + // unrecoverable failures. + shm.InitFromParent(aBuf); + return true; +} + +nsresult XPCJSContext::Initialize() { + if (StaticPrefs::javascript_options_external_thread_pool_DoNotUseDirectly()) { + size_t threadCount = TaskController::GetPoolThreadCount(); + size_t stackSize = TaskController::GetThreadStackSize(); + SetHelperThreadTaskCallback(&DispatchOffThreadTask, threadCount, stackSize); + } + + nsresult rv = + CycleCollectedJSContext::Initialize(nullptr, JS::DefaultHeapMaxBytes); + if (NS_WARN_IF(NS_FAILED(rv))) { + return rv; + } + + MOZ_ASSERT(Context()); + JSContext* cx = Context(); + + // The JS engine permits us to set different stack limits for system code, + // trusted script, and untrusted script. We have tests that ensure that + // we can always execute 10 "heavy" (eval+with) stack frames deeper in + // privileged code. Our stack sizes vary greatly in different configurations, + // so satisfying those tests requires some care. Manual measurements of the + // number of heavy stack frames achievable gives us the following rough data, + // ordered by the effective categories in which they are grouped in the + // JS_SetNativeStackQuota call (which predates this analysis). + // + // The following "Stack Frames" numbers come from `chromeLimit` in + // js/xpconnect/tests/chrome/test_bug732665.xul + // + // Platform | Build | Stack Quota | Stack Frames | Stack Frame Size + // ------------+-------+-------------+--------------+------------------ + // OSX 64 | Opt | 7MB | 1331 | ~5.4k + // OSX 64 | Debug | 7MB | 1202 | ~6.0k + // ------------+-------+-------------+--------------+------------------ + // Linux 32 | Opt | 7.875MB | 2513 | ~3.2k + // Linux 32 | Debug | 7.875MB | 2146 | ~3.8k + // ------------+-------+-------------+--------------+------------------ + // Linux 64 | Opt | 7.875MB | 1360 | ~5.9k + // Linux 64 | Debug | 7.875MB | 1180 | ~6.8k + // Linux 64 | ASan | 7.875MB | 473 | ~17.0k + // ------------+-------+-------------+--------------+------------------ + // Windows 32 | Opt | 984k | 188 | ~5.2k + // Windows 32 | Debug | 984k | 208 | ~4.7k + // ------------+-------+-------------+--------------+------------------ + // Windows 64 | Opt | 1.922MB | 189 | ~10.4k + // Windows 64 | Debug | 1.922MB | 175 | ~11.2k + // + // We tune the trusted/untrusted quotas for each configuration to achieve our + // invariants while attempting to minimize overhead. In contrast, our buffer + // between system code and trusted script is a very unscientific 10k. + const size_t kSystemCodeBuffer = 10 * 1024; + + // Our "default" stack is what we use in configurations where we don't have + // a compelling reason to do things differently. This is effectively 512KB + // on 32-bit platforms and 1MB on 64-bit platforms. + const size_t kDefaultStackQuota = 128 * sizeof(size_t) * 1024; + + // Set maximum stack size for different configurations. This value is then + // capped below because huge stacks are not web-compatible. + +#if defined(XP_MACOSX) || defined(DARWIN) + // MacOS has a gargantuan default stack size of 8MB. Go wild with 7MB, + // and give trusted script 180k extra. The stack is huge on mac anyway. + const size_t kUncappedStackQuota = 7 * 1024 * 1024; + const size_t kTrustedScriptBuffer = 180 * 1024; +#elif defined(XP_LINUX) && !defined(ANDROID) + // Most Linux distributions set default stack size to 8MB. Use it as the + // maximum value. + const size_t kStackQuotaMax = 8 * 1024 * 1024; +# if defined(MOZ_ASAN) || defined(DEBUG) + // Bug 803182: account for the 4x difference in the size of js::Interpret + // between optimized and debug builds. We use 2x since the JIT part + // doesn't increase much. + // See the standalone MOZ_ASAN branch below for the ASan case. + const size_t kStackQuotaMin = 2 * kDefaultStackQuota; +# else + const size_t kStackQuotaMin = kDefaultStackQuota; +# endif + // Allocate 128kB margin for the safe space. + const size_t kStackSafeMargin = 128 * 1024; + + struct rlimit rlim; + const size_t kUncappedStackQuota = + getrlimit(RLIMIT_STACK, &rlim) == 0 + ? std::max(std::min(size_t(rlim.rlim_cur - kStackSafeMargin), + kStackQuotaMax - kStackSafeMargin), + kStackQuotaMin) + : kStackQuotaMin; +# if defined(MOZ_ASAN) + // See the standalone MOZ_ASAN branch below for the ASan case. + const size_t kTrustedScriptBuffer = 450 * 1024; +# else + const size_t kTrustedScriptBuffer = 180 * 1024; +# endif +#elif defined(XP_WIN) + // 1MB is the default stack size on Windows. We use the -STACK linker flag + // (see WIN32_EXE_LDFLAGS in config/config.mk) to request a larger stack, so + // we determine the stack size at runtime. + const size_t kUncappedStackQuota = GetWindowsStackSize(); +# if defined(MOZ_ASAN) + // See the standalone MOZ_ASAN branch below for the ASan case. + const size_t kTrustedScriptBuffer = 450 * 1024; +# else + const size_t kTrustedScriptBuffer = (sizeof(size_t) == 8) + ? 180 * 1024 // win64 + : 120 * 1024; // win32 +# endif +#elif defined(MOZ_ASAN) + // ASan requires more stack space due to red-zones, so give it double the + // default (1MB on 32-bit, 2MB on 64-bit). ASAN stack frame measurements + // were not taken at the time of this writing, so we hazard a guess that + // ASAN builds have roughly thrice the stack overhead as normal builds. + // On normal builds, the largest stack frame size we might encounter is + // 9.0k (see above), so let's use a buffer of 9.0 * 5 * 10 = 450k. + // + // FIXME: Does this branch make sense for Windows and Android? + // (See bug 1415195) + const size_t kUncappedStackQuota = 2 * kDefaultStackQuota; + const size_t kTrustedScriptBuffer = 450 * 1024; +#elif defined(ANDROID) + // Android appears to have 1MB stacks. Allow the use of 3/4 of that size + // (768KB on 32-bit), since otherwise we can crash with a stack overflow + // when nearing the 1MB limit. + const size_t kUncappedStackQuota = + kDefaultStackQuota + kDefaultStackQuota / 2; + const size_t kTrustedScriptBuffer = sizeof(size_t) * 12800; +#else + // Catch-all configuration for other environments. +# if defined(DEBUG) + const size_t kUncappedStackQuota = 2 * kDefaultStackQuota; +# else + const size_t kUncappedStackQuota = kDefaultStackQuota; +# endif + // Given the numbers above, we use 50k and 100k trusted buffers on 32-bit + // and 64-bit respectively. + const size_t kTrustedScriptBuffer = sizeof(size_t) * 12800; +#endif + + // Avoid an unused variable warning on platforms where we don't use the + // default. + (void)kDefaultStackQuota; + + // Large stacks are not web-compatible so cap to a smaller value. + // See bug 1537609 and bug 1562700. + const size_t kStackQuotaCap = + StaticPrefs::javascript_options_main_thread_stack_quota_cap(); + const size_t kStackQuota = std::min(kUncappedStackQuota, kStackQuotaCap); + + JS_SetNativeStackQuota( + cx, kStackQuota, kStackQuota - kSystemCodeBuffer, + kStackQuota - kSystemCodeBuffer - kTrustedScriptBuffer); + + PROFILER_SET_JS_CONTEXT(cx); + + JS_AddInterruptCallback(cx, InterruptCallback); + + Runtime()->Initialize(cx); + + LoadStartupJSPrefs(this); + + // Watch for the JS boolean options. + ReloadPrefsCallback(nullptr, this); + Preferences::RegisterPrefixCallback(ReloadPrefsCallback, JS_OPTIONS_DOT_STR, + this); + +#ifdef FUZZING + Preferences::RegisterCallback(ReloadPrefsCallback, "fuzzing.enabled", this); +#endif + + // Initialize the MIME type used for the bytecode cache, after calling + // SetProcessBuildIdOp and loading JS prefs. + if (!nsContentUtils::InitJSBytecodeMimeType()) { + NS_ABORT_OOM(0); // Size is unknown. + } + + // When available, set the self-hosted shared memory to be read, so that we + // can decode the self-hosted content instead of parsing it. + auto& shm = xpc::SelfHostedShmem::GetSingleton(); + JS::SelfHostedCache selfHostedContent = shm.Content(); + JS::SelfHostedWriter writer = nullptr; + if (XRE_IsParentProcess() && sSelfHostedUseSharedMemory) { + // Only the Parent process has permissions to write to the self-hosted + // shared memory. + writer = CreateSelfHostedSharedMemory; + } + + if (!JS::InitSelfHostedCode(cx, selfHostedContent, writer)) { + // Note: If no exception is pending, failure is due to OOM. + if (!JS_IsExceptionPending(cx) || JS_IsThrowingOutOfMemory(cx)) { + NS_ABORT_OOM(0); // Size is unknown. + } + + // Failed to execute self-hosted JavaScript! Uh oh. + MOZ_CRASH("InitSelfHostedCode failed"); + } + + MOZ_RELEASE_ASSERT(Runtime()->InitializeStrings(cx), + "InitializeStrings failed"); + + return NS_OK; +} + +// static +uint32_t XPCJSContext::sInstanceCount; + +// static +StaticAutoPtr<WatchdogManager> XPCJSContext::sWatchdogInstance; + +// static +WatchdogManager* XPCJSContext::GetWatchdogManager() { + if (sWatchdogInstance) { + return sWatchdogInstance; + } + + MOZ_ASSERT(sInstanceCount == 0); + sWatchdogInstance = new WatchdogManager(); + return sWatchdogInstance; +} + +// static +XPCJSContext* XPCJSContext::NewXPCJSContext() { + XPCJSContext* self = new XPCJSContext(); + nsresult rv = self->Initialize(); + if (rv == NS_ERROR_OUT_OF_MEMORY) { + mozalloc_handle_oom(0); + } else if (NS_FAILED(rv)) { + MOZ_CRASH("new XPCJSContext failed to initialize."); + } + + if (self->Context()) { + return self; + } + + MOZ_CRASH("new XPCJSContext failed to initialize."); +} + +void XPCJSContext::BeforeProcessTask(bool aMightBlock) { + MOZ_ASSERT(NS_IsMainThread()); + + // Start the slow script timer. + mSlowScriptCheckpoint = mozilla::TimeStamp::NowLoRes(); + mSlowScriptSecondHalf = false; + mSlowScriptActualWait = mozilla::TimeDuration(); + mTimeoutAccumulated = false; + mExecutedChromeScript = false; + CycleCollectedJSContext::BeforeProcessTask(aMightBlock); +} + +void XPCJSContext::AfterProcessTask(uint32_t aNewRecursionDepth) { + // Record hangs in the parent process for telemetry. + if (mSlowScriptSecondHalf && XRE_IsE10sParentProcess()) { + double hangDuration = (mozilla::TimeStamp::NowLoRes() - + mSlowScriptCheckpoint + mSlowScriptActualWait) + .ToSeconds(); + // We use the pref to test this code. + double limit = sChromeSlowScriptTelemetryCutoff; + if (xpc::IsInAutomation()) { + double prefLimit = StaticPrefs::dom_max_chrome_script_run_time(); + if (prefLimit > 0) { + limit = std::min(prefLimit, sChromeSlowScriptTelemetryCutoff); + } + } + if (hangDuration > limit) { + if (!sTelemetryEventEnabled) { + sTelemetryEventEnabled = true; + Telemetry::SetEventRecordingEnabled("slow_script_warning"_ns, true); + } + + auto uriType = mExecutedChromeScript ? "browser"_ns : "content"_ns; + // Use AppendFloat to avoid printf-type APIs using locale-specific + // decimal separators, when we definitely want a `.`. + nsCString durationStr; + durationStr.AppendFloat(hangDuration); + auto extra = Some<nsTArray<Telemetry::EventExtraEntry>>( + {Telemetry::EventExtraEntry{"hang_duration"_ns, durationStr}, + Telemetry::EventExtraEntry{"uri_type"_ns, uriType}}); + Telemetry::RecordEvent( + Telemetry::EventID::Slow_script_warning_Shown_Browser, Nothing(), + extra); + } + } + + // Now that we're back to the event loop, reset the slow script checkpoint. + mSlowScriptCheckpoint = mozilla::TimeStamp(); + mSlowScriptSecondHalf = false; + + // Call cycle collector occasionally. + MOZ_ASSERT(NS_IsMainThread()); + nsJSContext::MaybePokeCC(); + CycleCollectedJSContext::AfterProcessTask(aNewRecursionDepth); + + // This exception might have been set if we called an XPCWrappedJS that threw, + // but now we're returning to the event loop, so nothing is going to look at + // this value again. Clear it to prevent leaks. + SetPendingException(nullptr); +} + +void XPCJSContext::MaybePokeGC() { nsJSContext::MaybePokeGC(); } + +bool XPCJSContext::IsSystemCaller() const { + return nsContentUtils::IsSystemCaller(Context()); +} |