Examples with GCScavengerForwardedHeader com.ibm.j9ddr.vm29.j9.gc.GCScavengerForwardedHeader used on opensource projects

Example 1 with GCScavengerForwardedHeader

use of com.ibm.j9ddr.vm29.j9.gc.GCScavengerForwardedHeader in project openj9 by eclipse.

the class CheckEngine method checkJ9ObjectPointer.

private int checkJ9ObjectPointer(J9ObjectPointer object, J9ObjectPointer[] newObject, GCHeapRegionDescriptor[] regionDesc) throws CorruptDataException {
    newObject[0] = object;
    if (object.isNull()) {
        return J9MODRON_GCCHK_RC_OK;
    }
    regionDesc[0] = findRegionForPointer(object, regionDesc[0]);
    if (regionDesc[0] == null) {
        /* Is the object on the stack? */
        GCVMThreadListIterator threadListIterator = GCVMThreadListIterator.from();
        while (threadListIterator.hasNext()) {
            J9VMThreadPointer vmThread = threadListIterator.next();
            if (isObjectOnStack(object, vmThread.stackObject())) {
                return J9MODRON_GCCHK_RC_STACK_OBJECT;
            }
        }
        UDATA classSlot = UDATA.cast(object.clazz());
        if (classSlot.eq(J9MODRON_GCCHK_J9CLASS_EYECATCHER)) {
            return J9MODRON_GCCHK_RC_OBJECT_SLOT_POINTS_TO_J9CLASS;
        }
        return J9MODRON_GCCHK_RC_NOT_FOUND;
    }
    // if (0 == regionDesc->objectAlignment) {
    if (!regionDesc[0].containsObjects()) {
        /* this is a heap region, but it's not intended for objects (could be free or an arraylet leaf) */
        return J9MODRON_GCCHK_RC_NOT_IN_OBJECT_REGION;
    }
    /* Now we know object is not on stack we can check that it's correctly aligned
		 * for a J9Object.
		 */
    if (object.anyBitsIn(J9MODRON_GCCHK_J9OBJECT_ALIGNMENT_MASK)) {
        return J9MODRON_GCCHK_RC_UNALIGNED;
    }
    if (isMidscavengeFlagSet()) {
        if (GCExtensions.isVLHGC() || (regionDesc[0].getTypeFlags().allBitsIn(MEMORY_TYPE_NEW))) {
            // TODO: ideally, we should only check this in the evacuate segment
            // TODO: do some safety checks first -- is there enough room in the segment?
            GCScavengerForwardedHeader scavengerForwardedHeader = GCScavengerForwardedHeader.fromJ9Object(object);
            if (scavengerForwardedHeader.isForwardedPointer()) {
                newObject[0] = scavengerForwardedHeader.getForwardedObject();
                reportForwardedObject(object, newObject[0]);
                // Replace the object and resume
                object = newObject[0];
                regionDesc[0] = findRegionForPointer(object, regionDesc[0]);
                if (regionDesc[0] == null) {
                    /* Is the object on the stack? */
                    GCVMThreadListIterator threadListIterator = GCVMThreadListIterator.from();
                    while (threadListIterator.hasNext()) {
                        J9VMThreadPointer vmThread = threadListIterator.next();
                        if (isObjectOnStack(object, vmThread.stackObject())) {
                            return J9MODRON_GCCHK_RC_STACK_OBJECT;
                        }
                    }
                    return J9MODRON_GCCHK_RC_NOT_FOUND;
                }
                // if (0 == regionDesc->objectAlignment) {
                if (!regionDesc[0].containsObjects()) {
                    /* this is a heap region, but it's not intended for objects (could be free or an arraylet leaf) */
                    return J9MODRON_GCCHK_RC_NOT_IN_OBJECT_REGION;
                }
                /* make sure the forwarded pointer is also aligned */
                if (object.anyBitsIn(J9MODRON_GCCHK_J9OBJECT_ALIGNMENT_MASK)) {
                    return J9MODRON_GCCHK_RC_UNALIGNED;
                }
            }
        }
    }
    if (isScavengerBackoutFlagSet()) {
        GCScavengerForwardedHeader scavengerForwardedHeader = GCScavengerForwardedHeader.fromJ9Object(object);
        if (scavengerForwardedHeader.isReverseForwardedPointer()) {
            newObject[0] = scavengerForwardedHeader.getReverseForwardedPointer();
            reportForwardedObject(object, newObject[0]);
            // Replace the object and resume
            object = newObject[0];
            regionDesc[0] = findRegionForPointer(object, regionDesc[0]);
            if (regionDesc[0] == null) {
                return J9MODRON_GCCHK_RC_NOT_FOUND;
            }
            if (!regionDesc[0].containsObjects()) {
                /* this is a heap region, but it's not intended for objects (could be free or an arraylet leaf) */
                return J9MODRON_GCCHK_RC_NOT_IN_OBJECT_REGION;
            }
            if (!regionDesc[0].getTypeFlags().allBitsIn(MEMORY_TYPE_NEW)) {
                /* reversed forwarded should point to Evacuate */
                return J9MODRON_GCCHK_RC_REVERSED_FORWARDED_OUTSIDE_EVACUATE;
            }
            /* make sure the forwarded pointer is also aligned */
            if (object.anyBitsIn(J9MODRON_GCCHK_J9OBJECT_ALIGNMENT_MASK)) {
                return J9MODRON_GCCHK_RC_UNALIGNED;
            }
        }
    }
    /* Check that elements of a double array are aligned on an 8-byte boundary.  For continuous
		 * arrays, verifying that the J9Indexable object is aligned on an 8-byte boundary is sufficient.
		 * For arraylets, depending on the layout, elements of the array may be stored on arraylet leafs
		 * or on the spine.  Arraylet leafs should always be aligned on 8-byte boundaries.  Checking both 
		 * the first and last element will ensure that we are always checking that elements are aligned 
		 * on the spine.
		 *  */
    long classShape = -1;
    try {
        classShape = ObjectModel.getClassShape(J9ObjectHelper.clazz(object)).longValue();
    } catch (CorruptDataException cde) {
    /* don't bother to report an error yet -- a later step will catch this. */
    }
    if (classShape == OBJECT_HEADER_SHAPE_DOUBLES) {
        J9IndexableObjectPointer array = J9IndexableObjectPointer.cast(object);
        int size = 0;
        VoidPointer elementPtr = VoidPointer.NULL;
        try {
            size = ObjectModel.getSizeInElements(object).intValue();
        } catch (InvalidDataTypeException ex) {
        // size in elements can not be larger then 2G but it is...
        // We could report an error at this point, but the C version
        // doesn't -- we'll catch it later
        } catch (IllegalArgumentException ex) {
        // We could report an error at this point, but the C version
        // doesn't -- we'll catch it later
        }
        if (0 != size) {
            elementPtr = ObjectModel.getElementAddress(array, 0, U64.SIZEOF);
            if (elementPtr.anyBitsIn(U64.SIZEOF - 1)) {
                return J9MODRON_GCCHK_RC_DOUBLE_ARRAY_UNALIGNED;
            }
            elementPtr = ObjectModel.getElementAddress(array, size - 1, U64.SIZEOF);
            if (elementPtr.anyBitsIn(U64.SIZEOF - 1)) {
                return J9MODRON_GCCHK_RC_DOUBLE_ARRAY_UNALIGNED;
            }
        }
    }
    return J9MODRON_GCCHK_RC_OK;
}

Example 2 with GCScavengerForwardedHeader

use of com.ibm.j9ddr.vm29.j9.gc.GCScavengerForwardedHeader in project openj9 by eclipse.

the class CheckObjectHeap method check.

@Override
public void check() {
    // Use iterators directly
    try {
        GCHeapRegionIterator regions = GCHeapRegionIterator.from();
        boolean midScavenge = _engine.isMidscavengeFlagSet();
        boolean isVLHGC = GCExtensions.isVLHGC();
        while (regions.hasNext()) {
            GCHeapRegionDescriptor region = GCHeapRegionDescriptor.fromHeapRegionDescriptor(regions.next());
            boolean isRegionTypeNew = region.getTypeFlags().allBitsIn(MEMORY_TYPE_NEW);
            GCObjectHeapIterator heapIterator = region.objectIterator(true, true);
            while (heapIterator.hasNext()) {
                J9ObjectPointer object = heapIterator.peek();
                if (midScavenge && (isVLHGC || isRegionTypeNew)) {
                    GCScavengerForwardedHeader scavengerForwardedHeader = GCScavengerForwardedHeader.fromJ9Object(object);
                    if (scavengerForwardedHeader.isForwardedPointer()) {
                        // forwarded pointer is discovered
                        // report it
                        _engine.reportForwardedObject(object, scavengerForwardedHeader.getForwardedObject());
                        // and skip it by advancing of iterator to the next object
                        UDATA objectSize = scavengerForwardedHeader.getObjectSize();
                        heapIterator.advance(objectSize);
                        _engine.pushPreviousObject(object);
                        continue;
                    }
                }
                int result = _engine.checkObjectHeap(object, region);
                if (result != J9MODRON_SLOT_ITERATOR_OK) {
                    break;
                }
                heapIterator.next();
                _engine.pushPreviousObject(object);
            }
        }
    } catch (CorruptDataException e) {
    // TODO: handle exception
    }
}

Example 3 with GCScavengerForwardedHeader

use of com.ibm.j9ddr.vm29.j9.gc.GCScavengerForwardedHeader in project openj9 by eclipse.

the class CheckEngine method checkSlotRememberedSet.

public int checkSlotRememberedSet(PointerPointer objectIndirect, MM_SublistPuddlePointer puddle) {
    J9ObjectPointer object;
    try {
        object = J9ObjectPointer.cast(objectIndirect.at(0));
        if (isMidscavengeFlagSet()) {
            /* during a scavenge, some RS entries may be tagged -- remove the tag */
            if (object.anyBitsIn(DEFERRED_RS_REMOVE_FLAG)) {
                object = object.untag(DEFERRED_RS_REMOVE_FLAG);
            }
        }
        int result = checkObjectIndirect(object);
        if (J9MODRON_GCCHK_RC_OK != result) {
            CheckError error = new CheckError(puddle, objectIndirect, _cycle, _currentCheck, result, _cycle.nextErrorCount());
            _reporter.report(error);
            return J9MODRON_SLOT_ITERATOR_OK;
        }
        /* Additional checks for the remembered set */
        if (object.notNull()) {
            GCHeapRegionDescriptor objectRegion = findRegionForPointer(object, null);
            if (objectRegion == null) {
                /* shouldn't happen, since checkObjectIndirect() already verified this object */
                CheckError error = new CheckError(puddle, objectIndirect, _cycle, _currentCheck, J9MODRON_GCCHK_RC_NOT_FOUND, _cycle.nextErrorCount());
                _reporter.report(error);
                return J9MODRON_SLOT_ITERATOR_OK;
            }
            /* we shouldn't have newspace references in the remembered set */
            if (objectRegion.getTypeFlags().allBitsIn(MEMORY_TYPE_NEW)) {
                CheckError error = new CheckError(puddle, objectIndirect, _cycle, _currentCheck, J9MODRON_GCCHK_RC_REMEMBERED_SET_WRONG_SEGMENT, _cycle.nextErrorCount());
                _reporter.report(error);
                return J9MODRON_SLOT_ITERATOR_OK;
            }
            boolean skipObject = false;
            if (isScavengerBackoutFlagSet()) {
                GCScavengerForwardedHeader scavengerForwardedHeader = GCScavengerForwardedHeader.fromJ9Object(object);
                if (scavengerForwardedHeader.isReverseForwardedPointer()) {
                    /* There is no reason to check object - is gone */
                    skipObject = true;
                }
            }
            if (!skipObject) {
                /* content of Remembered Set should be Old and Remembered */
                if (!ObjectModel.isOld(object) || !ObjectModel.isRemembered(object)) {
                    CheckError error = new CheckError(puddle, objectIndirect, _cycle, _currentCheck, J9MODRON_GCCHK_RC_REMEMBERED_SET_FLAGS, _cycle.nextErrorCount());
                    _reporter.report(error);
                    _reporter.reportObjectHeader(error, object, null);
                    return J9MODRON_SLOT_ITERATOR_OK;
                }
            }
        }
    } catch (CorruptDataException e) {
        // TODO : cde should be part of the error
        CheckError error = new CheckError(puddle, objectIndirect, _cycle, _currentCheck, J9MODRON_GCCHK_RC_CORRUPT_DATA_EXCEPTION, _cycle.nextErrorCount());
        _reporter.report(error);
    }
    return J9MODRON_SLOT_ITERATOR_OK;
}