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Allow Object to be modifiable in extended HCR
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Currently, Object is marked unmodifiable if extended HCR is enabled.
This change allows Object to be modified, but disallows use of the
extensions on Object.

Fixes: eclipse-openj9#17454

Signed-off-by: Graham Chapman <graham_chapman@ca.ibm.com>
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@gacholio @yathamravali
gacholio authored and yathamravali committed Sep 6, 2023
1 parent d12d10c commit ee9cc1e
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Showing 2 changed files with 21 additions and 21 deletions.
5 changes: 0 additions & 5 deletions runtime/bcutil/ROMClassCreationContext.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -247,11 +247,6 @@ class ROMClassCreationContext
&& (isClassAnon() || isClassHidden())
) {
unmodifiable = true;
} else if (NULL == J9VMJAVALANGOBJECT_OR_NULL(_javaVM)) {
/* Object is currently only allowed to be redefined in fast HCR */
if (areExtensionsEnabled(_javaVM)) {
unmodifiable = true;
}
}
}
return unmodifiable;
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37 changes: 21 additions & 16 deletions runtime/util/hshelp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -84,8 +84,8 @@ static UDATA classPairEquals(void* left, void* right, void* userData);
static UDATA findMethodInVTable(J9Method *method, UDATA *vTable);
static jvmtiError addClassesRequiringNewITables(J9JavaVM *vm, J9HashTable *classHashTable, UDATA *addedMethodCountPtr, UDATA *addedClassCountPtr, BOOLEAN fastHCR);
static jvmtiError verifyFieldsAreSame (J9VMThread * currentThread, UDATA fieldType, J9ROMClass * originalROMClass, J9ROMClass * replacementROMClass,
UDATA extensionsEnabled, UDATA * extensionsUsed);
static jvmtiError verifyMethodsAreSame (J9VMThread * currentThread, J9JVMTIClassPair * classPair, UDATA extensionsEnabled, UDATA * extensionsUsed);
UDATA extensionsEnabled, jvmtiError *extensionError);
static jvmtiError verifyMethodsAreSame (J9VMThread * currentThread, J9JVMTIClassPair * classPair, UDATA extensionsEnabled, jvmtiError *extensionError);
static int compareClassDepth (const void *leftPair, const void *rightPair);
static UDATA utfsAreIdentical(J9UTF8 * utf1, J9UTF8 * utf2);
static UDATA areUTFPairsIdentical(J9UTF8 * leftUtf1, J9UTF8 * leftUtf2, J9UTF8 * rightUtf1, J9UTF8 * rightUtf2);
Expand Down Expand Up @@ -2975,7 +2975,7 @@ determineClassesToRecreate(J9VMThread * currentThread, jint classCount,

static jvmtiError
verifyFieldsAreSame(J9VMThread * currentThread, UDATA fieldType, J9ROMClass * originalROMClass, J9ROMClass * replacementROMClass,
UDATA extensionsEnabled, UDATA * extensionsUsed)
UDATA extensionsEnabled, jvmtiError *extensionError)
{
jvmtiError rc = JVMTI_ERROR_NONE;
UDATA originalFieldCount;
Expand Down Expand Up @@ -3040,7 +3040,7 @@ verifyFieldsAreSame(J9VMThread * currentThread, UDATA fieldType, J9ROMClass * or

if ((fieldType == J9AccStatic) && (rc != JVMTI_ERROR_NONE)) {
if (extensionsEnabled) {
*extensionsUsed = 1;
*extensionError = rc;
rc = JVMTI_ERROR_NONE;
}
}
Expand Down Expand Up @@ -3073,9 +3073,9 @@ getOldestClassVersion(J9Class * clazz)
* \brief Verify that the methods follow allowed schema change rules
* \ingroup
*
* @param[in] currentThread
* @param[in] classPair old and replacing class
* @param[in] extensionsEnabled boolean indicating if the extensions are enabled
* @param[in] currentThread
* @param[in] classPair old and replacing class
* @param[out] extensionError error which would occur if extensions are not enabled
* @return error code
*
* If extensions are enabled then none of the schema verification errors matter as they are all allowed.
Expand All @@ -3092,7 +3092,7 @@ getOldestClassVersion(J9Class * clazz)
*
*/
static jvmtiError
verifyMethodsAreSame(J9VMThread * currentThread, J9JVMTIClassPair * classPair, UDATA extensionsEnabled, UDATA * extensionsUsed)
verifyMethodsAreSame(J9VMThread * currentThread, J9JVMTIClassPair * classPair, UDATA extensionsEnabled, jvmtiError *extensionError)
{
jvmtiError rc = JVMTI_ERROR_NONE;
J9Class * oldestRAMClass;
Expand All @@ -3106,7 +3106,6 @@ verifyMethodsAreSame(J9VMThread * currentThread, J9JVMTIClassPair * classPair, U

originalROMClass = oldestRAMClass->romClass;


/* Verify that the methods are the same */

if (originalROMClass->romMethodCount == replacementROMClass->romMethodCount) {
Expand Down Expand Up @@ -3244,7 +3243,7 @@ verifyMethodsAreSame(J9VMThread * currentThread, J9JVMTIClassPair * classPair, U
/* If extensions are enabled, any error aside of OOM (returned with earlier) is a hint that extensions have been used
* and should not be treated as an error */
if (rc != JVMTI_ERROR_NONE) {
*extensionsUsed = 1;
*extensionError = rc;
}

return JVMTI_ERROR_NONE;
Expand Down Expand Up @@ -3354,7 +3353,7 @@ verifyClassesAreCompatible(J9VMThread * currentThread, jint class_count, J9JVMTI
jint i;

for (i = 0; i < class_count; ++i) {
UDATA classUsesExtensions = 0;
jvmtiError extensionError = JVMTI_ERROR_NONE;
J9ROMClass * originalROMClass = classPairs[i].originalRAMClass->romClass;
J9ROMClass * replacementROMClass = classPairs[i].replacementClass.romClass;
jvmtiError rc;
Expand Down Expand Up @@ -3429,26 +3428,32 @@ verifyClassesAreCompatible(J9VMThread * currentThread, jint class_count, J9JVMTI

/* Verify that instance fields are the same */

rc = verifyFieldsAreSame(currentThread, 0, originalROMClass, replacementROMClass, extensionsEnabled, &classUsesExtensions);
rc = verifyFieldsAreSame(currentThread, 0, originalROMClass, replacementROMClass, extensionsEnabled, &extensionError);
if (rc != JVMTI_ERROR_NONE) {
return rc;
}


/* Verify that static fields are the same */

rc = verifyFieldsAreSame(currentThread, J9AccStatic, originalROMClass, replacementROMClass, extensionsEnabled, &classUsesExtensions);
rc = verifyFieldsAreSame(currentThread, J9AccStatic, originalROMClass, replacementROMClass, extensionsEnabled, &extensionError);
if (rc != JVMTI_ERROR_NONE) {
return rc;
}

/* Verify that the methods are the same */

rc = verifyMethodsAreSame(currentThread, &classPairs[i], extensionsEnabled, &classUsesExtensions);
rc = verifyMethodsAreSame(currentThread, &classPairs[i], extensionsEnabled, &extensionError);
if (rc != JVMTI_ERROR_NONE) {
return rc;
}

/* Disallow extensions for java.lang.Object */
if (JVMTI_ERROR_NONE != extensionError) {
if (NULL == J9ROMCLASS_SUPERCLASSNAME(originalROMClass)){
return extensionError;
}
}

#if JAVA_SPEC_VERSION >= 15
/* Verify that records attributes are the same */
rc = verifyRecordAttributesAreSame(originalROMClass, replacementROMClass);
Expand Down Expand Up @@ -3497,7 +3502,7 @@ verifyClassesAreCompatible(J9VMThread * currentThread, jint class_count, J9JVMTI
}
#endif /* JAVA_SPEC_VERSION >= 11 */

if (0 != classUsesExtensions) {
if (JVMTI_ERROR_NONE != extensionError) {
classPairs[i].flags |= J9JVMTI_CLASS_PAIR_FLAG_USES_EXTENSIONS;
*extensionsUsed = 1;
}
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