8212155: Race condition when posting dynamic_code_generated event leads to JVM crash

Reviewed-by: phh, shade
Backport-of: 64ec8b3e5c8a8d44c92591710d73b833f13c1500

hotspot/src/share/vm/prims/jvmtiExport.cpp

@@ -1890,13 +1890,17 @@ void JvmtiExport::post_dynamic_code_generated_while_holding_locks(const char* na
                                                                   address code_begin, address code_end)
 {
   // register the stub with the current dynamic code event collector
-  JvmtiThreadState* state = JvmtiThreadState::state_for(JavaThread::current());
-  // state can only be NULL if the current thread is exiting which
-  // should not happen since we're trying to post an event
-  guarantee(state != NULL, "attempt to register stub via an exiting thread");
-  JvmtiDynamicCodeEventCollector* collector = state->get_dynamic_code_event_collector();
-  guarantee(collector != NULL, "attempt to register stub without event collector");
-  collector->register_stub(name, code_begin, code_end);
+  // Cannot take safepoint here so do not use state_for to get
+  // jvmti thread state.
+  // The collector and/or state might be NULL if JvmtiDynamicCodeEventCollector
+  // has been initialized while JVMTI_EVENT_DYNAMIC_CODE_GENERATED was disabled.
+  JvmtiThreadState* state = JavaThread::current()->jvmti_thread_state();
+  if (state != NULL) {
+    JvmtiDynamicCodeEventCollector *collector = state->get_dynamic_code_event_collector();
+    if (collector != NULL) {
+      collector->register_stub(name, code_begin, code_end);
+    }
+  }
 }
 
 // Collect all the vm internally allocated objects which are visible to java world

hotspot/test/serviceability/jvmti/DynamicCodeGenerated/DynamicCodeGenerated.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+public class DynamicCodeGenerated {
+    static {
+        System.loadLibrary("DynamicCodeGenerated");
+    }
+    public static native void changeEventNotificationMode();
+
+    public static void main(String[] args) {
+        // Try to enable DynamicCodeGenerated event while it is posted
+        // using JvmtiDynamicCodeEventCollector from VtableStubs::find_stub
+        Thread t = new Thread(() -> {
+            changeEventNotificationMode();
+        });
+        t.setDaemon(true);
+        t.start();
+
+        for (int i = 0; i < 2000; i++) {
+            new Thread(() -> {
+                String result = "string" + System.currentTimeMillis();
+
+                // Keep a reference to result
+                if (result.hashCode() == System.currentTimeMillis()) {
+                    // Shouldn't happen
+                    return;
+                }
+            }).start();
+        }
+    }
+}

hotspot/test/serviceability/jvmti/DynamicCodeGenerated/DynamicCodeGeneratedTest.sh

@@ -0,0 +1,82 @@
+#!/bin/sh
+
+# Copyright (c) 2012, 2025, Oracle and/or its affiliates. All rights reserved.
+# DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+#
+# This code is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License version 2 only, as
+# published by the Free Software Foundation.
+#
+# This code is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# version 2 for more details (a copy is included in the LICENSE file that
+# accompanied this code).
+#
+# You should have received a copy of the GNU General Public License version
+# 2 along with this work; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+# or visit www.oracle.com if you need additional information or have any
+# questions.
+
+# @test DynamicCodeGeneratedTest.sh
+# @bug 8212155
+# @summary Test concurrent enabling and posting of DynamicCodeGenerated events.
+# @run shell DynamicCodeGeneratedTest.sh
+
+if [ "$TESTSRC" = "" ]
+then TESTSRC=.
+fi
+
+if [ "$TESTJAVA" = "" ]
+then
+  PARENT=$(dirname $(which java))
+  TESTJAVA=$(dirname $PARENT)
+  echo "TESTJAVA not set, selecting " $TESTJAVA
+  echo "If this is incorrect, try setting the variable manually."
+fi
+
+# set platform-dependent variables
+OS=$(uname -s)
+case "$OS" in
+  Linux )
+    ARCHFLAG=
+    $TESTJAVA/bin/java -version 2>&1 | grep '64-Bit' > /dev/null
+    if [ $? -eq '0' ]
+    then
+        ARCH="amd64"
+    else
+        ARCH="i386"
+        ARCHFLAG="-m32 -march=i386"
+    fi
+    ;;
+  * )
+    echo "Test passed, unrecognized system."
+    exit 0;
+    ;;
+esac
+
+echo "OS-ARCH is" linux-$ARCH
+$TESTJAVA/jre/bin/java -fullversion 2>&1
+
+which gcc >/dev/null 2>&1
+if [ "$?" -ne '0' ]
+then
+    echo "No C compiler found. Test passed."
+    exit 0
+fi
+
+JAVA=$TESTJAVA/jre/bin/java
+JAVAC=$TESTJAVA/bin/javac
+JAVAH=$TESTJAVA/bin/javah
+
+$JAVAC -d . $TESTSRC/DynamicCodeGenerated.java
+$JAVAH -jni -classpath . -d . DynamicCodeGenerated
+
+gcc --shared $ARCHFLAG -fPIC -O -I$TESTJAVA/include -I$TESTJAVA/include/linux -I. -o libDynamicCodeGenerated.so $TESTSRC/libDynamicCodeGenerated.cpp
+
+LD_LIBRARY_PATH=. $JAVA -classpath . -agentlib:DynamicCodeGenerated DynamicCodeGenerated
+
+exit $?

hotspot/test/serviceability/jvmti/DynamicCodeGenerated/libDynamicCodeGenerated.cpp

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include <string.h>
+#include <jvmti.h>
+
+static jvmtiEnv* jvmti = NULL;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+JNIEXPORT
+void JNICALL Java_DynamicCodeGenerated_changeEventNotificationMode(JNIEnv* jni, jclass cls) {
+  while (true) {
+    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
+    jvmti->SetEventNotificationMode(JVMTI_DISABLE, JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
+  }
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+void JNICALL DynamicCodeGenerated(jvmtiEnv* jvmti, const char* name, const void* address, jint length) {
+
+}
+
+jint Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
+    vm->GetEnv((void**)&jvmti, JVMTI_VERSION_1_0);
+    jvmtiEventCallbacks callbacks;
+    memset(&callbacks, 0, sizeof(callbacks));
+    callbacks.DynamicCodeGenerated = DynamicCodeGenerated;
+    jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
+
+    return 0;
+}