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Update ClassLoader.findNative to support JEP 472 #20840

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Dec 18, 2024
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Update ClassLoader.findNative to support JEP 472 #20840

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2 changes: 1 addition & 1 deletion jcl/src/java.base/share/classes/java/lang/Access.java
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Original file line number Diff line number Diff line change
Expand Up @@ -592,7 +592,7 @@ public PrintStream initialSystemErr() {
/*[ENDIF] JAVA_SPEC_VERSION >= 23 */

public long findNative(ClassLoader loader, String entryName) {
return ClassLoader.findNative(loader, entryName);
return ClassLoader.findNative0(loader, entryName);
}

@Override
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20 changes: 19 additions & 1 deletion jcl/src/java.base/share/classes/java/lang/ClassLoader.java
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Expand Up @@ -72,6 +72,10 @@
import jdk.internal.reflect.CallerSensitiveAdapter;
/*[ENDIF] JAVA_SPEC_VERSION >= 18 */

/*[IF JAVA_SPEC_VERSION >= 24]*/
import jdk.internal.reflect.Reflection;
/*[ENDIF] JAVA_SPEC_VERSION >= 24 */

/*[IF CRIU_SUPPORT]*/
import openj9.internal.criu.NotCheckpointSafe;
/*[ENDIF] CRIU_SUPPORT*/
Expand Down Expand Up @@ -2101,13 +2105,27 @@ static void loadLibrary(Class<?> caller, String libName) {
}
}

static long findNative(ClassLoader loader, String entryName) {
/*[IF JAVA_SPEC_VERSION >= 24]*/
static long findNative1(ClassLoader loader, String entryName, Class<?> cls, String javaName) {
long address = findNative0(loader, entryName);
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Does the spec specify this order of checks? As in, if we look for a method that doesnt exist in a class that doesnt have native access, which error shows up?

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The spec does not explicitly define the order of checks, but we can infer it from the available OpenJDK tests. Currently, we are aligned with the RI since we pass the majority of failing tests in #20354.


if ((loader != null) && (address != 0)) {
Reflection.ensureNativeAccess(cls, cls, javaName, true);
}

return address;
}
/*[ENDIF] JAVA_SPEC_VERSION >= 24 */

static long findNative0(ClassLoader loader, String entryName) {
NativeLibraries nativelib;

if ((loader == null) || (loader == bootstrapClassLoader)) {
nativelib = BootLoader.getNativeLibraries();
} else {
nativelib = loader.nativelibs;
}

return nativelib.find(entryName);
}
/*[ENDIF] JAVA_SPEC_VERSION >= 15 */
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3 changes: 2 additions & 1 deletion runtime/oti/vmconstantpool.xml
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Expand Up @@ -474,7 +474,8 @@ SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-ex
<virtualmethodref class="java/lang/ClassLoader" name="loadClass" signature="(Ljava/lang/String;)Ljava/lang/Class;"/>
<specialmethodref class="java/lang/Thread" name="uncaughtException" signature="(Ljava/lang/Throwable;)V"/>
<specialmethodref class="java/lang/Thread" name="&lt;init>" signature="(Ljava/lang/String;Ljava/lang/Object;IZ)V"/>
<staticmethodref class="java/lang/ClassLoader" name="findNative" signature="(Ljava/lang/ClassLoader;Ljava/lang/String;)J" versions="17-"/>
<staticmethodref class="java/lang/ClassLoader" name="findNative0" signature="(Ljava/lang/ClassLoader;Ljava/lang/String;)J" versions="17-23"/>
<staticmethodref class="java/lang/ClassLoader" name="findNative1" signature="(Ljava/lang/ClassLoader;Ljava/lang/String;Ljava/lang/Class;Ljava/lang/String;)J" versions="24-"/>

<fieldref class="java/lang/J9VMInternals$ClassInitializationLock" name="theClass" signature="Ljava/lang/Class;"/>

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31 changes: 23 additions & 8 deletions runtime/vm/bindnatv.cpp
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Expand Up @@ -1105,17 +1105,32 @@ lookupJNINative(J9VMThread *currentThread, J9NativeLibrary *nativeLibrary, J9Met
#if JAVA_SPEC_VERSION >= 17
if (NULL == nativeLibrary) {
internalAcquireVMAccess(currentThread);
j9object_t entryName = vm->memoryManagerFunctions->j9gc_createJavaLangString(currentThread, (U_8*)symbolName, strlen(symbolName), 0);
J9MemoryManagerFunctions *mmFuncs = vm->memoryManagerFunctions;
j9object_t entryName = mmFuncs->j9gc_createJavaLangString(currentThread, (U_8*)symbolName, strlen(symbolName), 0);
if (NULL != entryName) {
j9object_t classLoaderObject = J9_CLASS_FROM_METHOD(nativeMethod)->classLoader->classLoaderObject;
J9Method *findNativeMethod = J9VMJAVALANGCLASSLOADER_FINDNATIVE_METHOD(vm);
UDATA args[] = {(UDATA)classLoaderObject, (UDATA)entryName};
internalRunStaticMethod(currentThread, findNativeMethod, TRUE, (sizeof(args) / sizeof(UDATA)), args);
functionAddress = (UDATA*)(*(U_64*)&(currentThread->returnValue));
#if JAVA_SPEC_VERSION >= 24
J9ROMMethod *nativeROMMethod = J9_ROM_METHOD_FROM_RAM_METHOD(nativeMethod);
j9object_t javaName = mmFuncs->j9gc_createJavaLangStringWithUTFCache(currentThread, J9ROMMETHOD_NAME(nativeROMMethod));
if (NULL != javaName)
#endif /* JAVA_SPEC_VERSION >= 24 */
{
J9Class *nativeMethodCls = J9_CLASS_FROM_METHOD(nativeMethod);
j9object_t classLoaderObject = nativeMethodCls->classLoader->classLoaderObject;
#if JAVA_SPEC_VERSION >= 24
j9object_t classObject = nativeMethodCls->classObject;
J9Method *findNativeMethod = J9VMJAVALANGCLASSLOADER_FINDNATIVE1_METHOD(vm);
UDATA args[] = {(UDATA)classLoaderObject, (UDATA)entryName, (UDATA)classObject, (UDATA)javaName};
#else /* JAVA_SPEC_VERSION >= 24 */
J9Method *findNativeMethod = J9VMJAVALANGCLASSLOADER_FINDNATIVE0_METHOD(vm);
UDATA args[] = {(UDATA)classLoaderObject, (UDATA)entryName};
#endif /* JAVA_SPEC_VERSION >= 24 */
internalRunStaticMethod(currentThread, findNativeMethod, TRUE, (sizeof(args) / sizeof(UDATA)), args);
functionAddress = (UDATA*)(*(U_64*)&(currentThread->returnValue));
#if defined(J9VM_OPT_JAVA_OFFLOAD_SUPPORT)
doSwitching = ((UDATA)functionAddress) & J9_NATIVE_LIBRARY_SWITCH_MASK;
functionAddress = (UDATA *)(((UDATA)functionAddress) & ~(UDATA)J9_NATIVE_LIBRARY_SWITCH_MASK);
doSwitching = ((UDATA)functionAddress) & J9_NATIVE_LIBRARY_SWITCH_MASK;
functionAddress = (UDATA *)(((UDATA)functionAddress) & ~(UDATA)J9_NATIVE_LIBRARY_SWITCH_MASK);
#endif /* defined(J9VM_OPT_JAVA_OFFLOAD_SUPPORT) */
}
}
/* always clear pending exception, might retry later */
VM_VMHelpers::clearException(currentThread);
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