8336663: [JVMCI] VM Crash on ZGC due to incompatible handle returned by HotSpotJVMCIRuntime#getJObjectValue

Reviewed-by: dnsimon, never

Author: Tomas Zezula

src/hotspot/share/jvmci/jvmciCompilerToVM.cpp

@@ -94,6 +94,12 @@ static void requireInHotSpot(const char* caller, JVMCI_TRAPS) {
   }
 }
 
+static void requireNotInHotSpot(const char* caller, JVMCI_TRAPS) {
+    if (JVMCIENV->is_hotspot()) {
+        JVMCI_THROW_MSG(IllegalStateException, err_msg("Cannot call %s from HotSpot", caller));
+    }
+}
+
 class JVMCITraceMark : public StackObj {
   const char* _msg;
  public:
@@ -702,6 +708,17 @@ C2V_VMENTRY_NULL(jobject, lookupJClass, (JNIEnv* env, jobject, jlong jclass_valu
     return JVMCIENV->get_jobject(result);
 C2V_END
 
+C2V_VMENTRY_0(jlong, getJObjectValue, (JNIEnv* env, jobject, jobject constant_jobject))
+    requireNotInHotSpot("getJObjectValue", JVMCI_CHECK_0);
+    if (!THREAD->has_last_Java_frame()) {
+        JVMCI_THROW_MSG_0(IllegalStateException, err_msg("Cannot call getJObjectValue without Java frame anchor"));
+    }
+    JVMCIObject constant = JVMCIENV->wrap(constant_jobject);
+    Handle constant_value = JVMCIENV->asConstant(constant, JVMCI_CHECK_0);
+    jobject jni_handle = JNIHandles::make_local(THREAD, constant_value());
+    return reinterpret_cast<jlong>(jni_handle);
+C2V_END
+
 C2V_VMENTRY_NULL(jobject, getUncachedStringInPool, (JNIEnv* env, jobject, ARGUMENT_PAIR(cp), jint index))
   constantPoolHandle cp(THREAD, UNPACK_PAIR(ConstantPool, cp));
   constantTag tag = cp->tag_at(index);
@@ -3254,6 +3271,7 @@ JNINativeMethod CompilerToVM::methods[] = {
   {CC "shouldInlineMethod",                           CC "(" HS_METHOD2 ")Z",                                                               FN_PTR(shouldInlineMethod)},
   {CC "lookupType",                                   CC "(" STRING HS_KLASS2 "IZ)" HS_RESOLVED_TYPE,                                       FN_PTR(lookupType)},
   {CC "lookupJClass",                                 CC "(J)" HS_RESOLVED_TYPE,                                                            FN_PTR(lookupJClass)},
+  {CC "getJObjectValue",                              CC "(" OBJECTCONSTANT ")J",                                                           FN_PTR(getJObjectValue)},
   {CC "getArrayType",                                 CC "(C" HS_KLASS2 ")" HS_KLASS,                                                       FN_PTR(getArrayType)},
   {CC "lookupClass",                                  CC "(" CLASS ")" HS_RESOLVED_TYPE,                                                    FN_PTR(lookupClass)},
   {CC "lookupNameInPool",                             CC "(" HS_CONSTANT_POOL2 "II)" STRING,                                                FN_PTR(lookupNameInPool)},

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java

@@ -289,6 +289,12 @@ HotSpotResolvedJavaType lookupType(ClassLoader classLoader, String name) throws
 
     native HotSpotResolvedJavaType lookupJClass(long jclass);
 
+    /**
+     * Gets the {@code jobject} value wrapped by {@code peerObject}.
+     * Must not be called if {@link Services#IS_IN_NATIVE_IMAGE} is {@code false}.
+     */
+    native long getJObjectValue(HotSpotObjectConstantImpl peerObject);
+
     /**
      * Resolves the entry at index {@code cpi} in {@code constantPool} to an interned String object.
      *

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java

@@ -925,23 +925,23 @@ JavaType lookupTypeInternal(String name, HotSpotResolvedObjectType accessingType
     }
 
     /**
-     * Gets the {@code jobject} value wrapped by {@code peerObject}. The returned "naked" value is
-     * only valid as long as {@code peerObject} is valid. Note that the latter may be shorter than
-     * the lifetime of {@code peerObject}. As such, this method should only be used to pass an
-     * object parameter across a JNI call from the JVMCI shared library to HotSpot. This method must
-     * only be called from within the JVMCI shared library.
+     * Gets the {@code jobject} value wrapped by {@code peerObject}. The returned value is
+     * a JNI local reference whose lifetime is scoped by the nearest Java caller (from
+     * HotSpot's perspective). You can use {@code PushLocalFrame} and {@code PopLocalFrame} to
+     * shorten the lifetime of the reference. The current thread's state must be
+     * {@code _thread_in_native}. A call from the JVMCI shared library (e.g. libgraal) is in such
+     * a state.
      *
-     * @param peerObject a reference to an object in the peer runtime
-     * @return the {@code jobject} value wrapped by {@code peerObject}
+     * @param peerObject a reference to an object in the HotSpot heap
+     * @return the {@code jobject} value unpacked from {@code peerObject}
      * @throws IllegalArgumentException if the current runtime is not the JVMCI shared library or
-     *             {@code peerObject} is not a peer object reference
+     *             {@code peerObject} is not a HotSpot heap object reference
+     * @throws IllegalStateException if not called from within the JVMCI shared library
+     *         or if there is no Java caller frame on the stack
+     *         (i.e., JavaThread::has_last_Java_frame returns false)
      */
     public long getJObjectValue(HotSpotObjectConstant peerObject) {
-        if (peerObject instanceof IndirectHotSpotObjectConstantImpl) {
-            IndirectHotSpotObjectConstantImpl remote = (IndirectHotSpotObjectConstantImpl) peerObject;
-            return remote.getHandle();
-        }
-        throw new IllegalArgumentException("Cannot get jobject value for " + peerObject + " (" + peerObject.getClass().getName() + ")");
+        return compilerToVm.getJObjectValue((HotSpotObjectConstantImpl)peerObject);
     }
 
     @Override