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8365192: post_meth_exit should be in vm state when calling get_jvmti_thread_state #26713

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8365192: post_meth_exit should be in vm state when calling get_jvmti_thread_state #26713

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8365192: post_meth_exit should be in vm state when calling get_jvmti_…
lmesnik Aug 9, 2025
7cce73e
simplified after feedback
lmesnik Aug 13, 2025
977c9eb
fixed name
lmesnik Aug 13, 2025
31046ba
wong phase
lmesnik Aug 13, 2025
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lmesnik Aug 13, 2025
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8 changes: 6 additions & 2 deletions src/hotspot/share/prims/jvmtiExport.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -420,6 +420,7 @@ JvmtiExport::get_jvmti_interface(JavaVM *jvm, void **penv, jint version) {
JvmtiThreadState*
JvmtiExport::get_jvmti_thread_state(JavaThread *thread, bool allow_suspend) {
assert(thread == JavaThread::current(), "must be current thread");
assert(thread->thread_state() == _thread_in_vm, "thread should be in vm");
if (thread->is_vthread_mounted() && thread->jvmti_thread_state() == nullptr) {
JvmtiEventController::thread_started(thread);
if (allow_suspend && thread->is_suspended()) {
Expand Down Expand Up @@ -1831,7 +1832,11 @@ void JvmtiExport::post_method_exit(JavaThread* thread, Method* method, frame cur
HandleMark hm(thread);
methodHandle mh(thread, method);

JvmtiThreadState *state = get_jvmti_thread_state(thread);
JvmtiThreadState *state = nullptr;
JavaThread* current = thread; // for JRT_BLOCK
JRT_BLOCK
state = get_jvmti_thread_state(thread);
JRT_BLOCK_END
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The JRT_BLOCK is defined as:

#define JRT_BLOCK                                                    \
    {                                                                \
    assert(current == JavaThread::current(), "Must be");             \
    ThreadInVMfromJava __tiv(current);                               \
    JavaThread* THREAD = current; /* For exception macros. */        \
    DEBUG_ONLY(VMEntryWrapper __vew;)

I'd suggest something like this instead of using JRT_BLOCK:

-  JvmtiThreadState *state = get_jvmti_thread_state(thread);
+   JvmtiThreadState *state = nullptr;
+  {
+     ThreadInVMfromJava __tiv(thread);
+     state = get_jvmti_thread_state(thread);
+  }

Alternatively, the JRT_BLOCK can be started at the line 1837 and ended with JRT_BLOCK_END at the line 1875. Not sure, what issue we can encounter with this though. At least, it is worth a try.

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As I understand the post_method_entry was called via JRT_BLOCK_ENTRY and not JRT_BLOCK by the reason. We need to be in Java. See comments for the method invocation.

// This is a JRT_BLOCK_ENTRY because we have to stash away the return oop
// before transitioning to VM, and restore it after transitioning back
// to Java. The return oop at the top-of-stack, is not walked by the GC.
JRT_BLOCK_ENTRY(void, InterpreterRuntime::post_method_exit(JavaThread* current))
  LastFrameAccessor last_frame(current);
  JvmtiExport::post_method_exit(current, last_frame.method(), last_frame.get_frame());
JRT_END

And thanks for simplification, it is a good idea. I've updated the PR.
I am running tier1-8 for Hotspot tests to ensure that nothing is broken.


if (state == nullptr || !state->is_interp_only_mode()) {
// for any thread that actually wants method exit, interp_only_mode is set
Expand Down Expand Up @@ -1867,7 +1872,6 @@ void JvmtiExport::post_method_exit(JavaThread* thread, Method* method, frame cur
// Deferred transition to VM, so we can stash away the return oop before GC
// Note that this transition is not needed when throwing an exception, because
// there is no oop to retain.
JavaThread* current = thread; // for JRT_BLOCK
JRT_BLOCK
post_method_exit_inner(thread, mh, state, exception_exit, current_frame, value);
JRT_BLOCK_END
Expand Down