Remove FramePop trace listener if no outstanding events
Previously we would leave the JvmtiMethodTraceListener installed
forever if we even had a FramePop event requested. This was to prevent
any possible UAF issues with shadow-frames. This changes it so we will
check if there are any outstanding shadow-frames when the event is
disabled. If there are not any left we will remove it and remove the
deopts. This should improve performance after a frame-pop event is
used.
Bug: 74240081
Bug: 34414072
Test: ./test.py --host -j50
Test: Debug system-server a bit and use Step-Out.
Change-Id: I5fdb8ccce95ba51d6113df12e01bb158d210a5b2
diff --git a/openjdkjvmti/events.cc b/openjdkjvmti/events.cc
index 8b40a7e..07b1529 100644
--- a/openjdkjvmti/events.cc
+++ b/openjdkjvmti/events.cc
@@ -1004,6 +1004,27 @@
return false;
}
+void EventHandler::SetupFramePopTraceListener(bool enable) {
+ if (enable) {
+ frame_pop_enabled = true;
+ SetupTraceListener(method_trace_listener_.get(), ArtJvmtiEvent::kFramePop, enable);
+ } else {
+ // remove the listener if we have no outstanding frames.
+ {
+ art::ReaderMutexLock mu(art::Thread::Current(), envs_lock_);
+ for (ArtJvmTiEnv* env : envs) {
+ art::ReaderMutexLock event_mu(art::Thread::Current(), env->event_info_mutex_);
+ if (!env->notify_frames.empty()) {
+ // Leaving FramePop listener since there are unsent FramePop events.
+ return;
+ }
+ }
+ frame_pop_enabled = false;
+ }
+ SetupTraceListener(method_trace_listener_.get(), ArtJvmtiEvent::kFramePop, enable);
+ }
+}
+
// Handle special work for the given event type, if necessary.
void EventHandler::HandleEventType(ArtJvmtiEvent event, bool enable) {
switch (event) {
@@ -1018,14 +1039,14 @@
case ArtJvmtiEvent::kGarbageCollectionFinish:
SetupGcPauseTracking(gc_pause_listener_.get(), event, enable);
return;
- // FramePop can never be disabled once it's been turned on since we would either need to deal
- // with dangling pointers or have missed events.
- // TODO We really need to make this not the case anymore.
+ // FramePop can never be disabled once it's been turned on if it was turned off with outstanding
+ // pop-events since we would either need to deal with dangling pointers or have missed events.
case ArtJvmtiEvent::kFramePop:
- if (!enable || (enable && frame_pop_enabled)) {
+ if (enable && frame_pop_enabled) {
+ // The frame-pop event was held on by pending events so we don't need to do anything.
break;
} else {
- SetupTraceListener(method_trace_listener_.get(), event, enable);
+ SetupFramePopTraceListener(enable);
break;
}
case ArtJvmtiEvent::kMethodEntry:
diff --git a/openjdkjvmti/events.h b/openjdkjvmti/events.h
index 8141eff..bf12cb1 100644
--- a/openjdkjvmti/events.h
+++ b/openjdkjvmti/events.h
@@ -247,6 +247,9 @@
private:
void SetupTraceListener(JvmtiMethodTraceListener* listener, ArtJvmtiEvent event, bool enable);
+ // Specifically handle the FramePop event which it might not always be possible to turn off.
+ void SetupFramePopTraceListener(bool enable);
+
template <ArtJvmtiEvent kEvent, typename ...Args>
ALWAYS_INLINE
inline std::vector<impl::EventHandlerFunc<kEvent>> CollectEvents(art::Thread* thread,