/* * Copyright (c) 2003, 2011, 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 "precompiled.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/verifier.hpp" #include "code/codeCache.hpp" #include "interpreter/oopMapCache.hpp" #include "interpreter/rewriter.hpp" #include "memory/gcLocker.hpp" #include "memory/universe.inline.hpp" #include "oops/klassVtable.hpp" #include "prims/jvmtiImpl.hpp" #include "prims/jvmtiRedefineClasses.hpp" #include "prims/methodComparator.hpp" #include "runtime/deoptimization.hpp" #include "runtime/relocator.hpp" #include "utilities/bitMap.inline.hpp" objArrayOop VM_RedefineClasses::_old_methods = NULL; objArrayOop VM_RedefineClasses::_new_methods = NULL; methodOop* VM_RedefineClasses::_matching_old_methods = NULL; methodOop* VM_RedefineClasses::_matching_new_methods = NULL; methodOop* VM_RedefineClasses::_deleted_methods = NULL; methodOop* VM_RedefineClasses::_added_methods = NULL; int VM_RedefineClasses::_matching_methods_length = 0; int VM_RedefineClasses::_deleted_methods_length = 0; int VM_RedefineClasses::_added_methods_length = 0; klassOop VM_RedefineClasses::_the_class_oop = NULL; VM_RedefineClasses::VM_RedefineClasses(jint class_count, const jvmtiClassDefinition *class_defs, JvmtiClassLoadKind class_load_kind) { _class_count = class_count; _class_defs = class_defs; _class_load_kind = class_load_kind; _res = JVMTI_ERROR_NONE; } bool VM_RedefineClasses::doit_prologue() { if (_class_count == 0) { _res = JVMTI_ERROR_NONE; return false; } if (_class_defs == NULL) { _res = JVMTI_ERROR_NULL_POINTER; return false; } for (int i = 0; i < _class_count; i++) { if (_class_defs[i].klass == NULL) { _res = JVMTI_ERROR_INVALID_CLASS; return false; } if (_class_defs[i].class_byte_count == 0) { _res = JVMTI_ERROR_INVALID_CLASS_FORMAT; return false; } if (_class_defs[i].class_bytes == NULL) { _res = JVMTI_ERROR_NULL_POINTER; return false; } } // Start timer after all the sanity checks; not quite accurate, but // better than adding a bunch of stop() calls. RC_TIMER_START(_timer_vm_op_prologue); // We first load new class versions in the prologue, because somewhere down the // call chain it is required that the current thread is a Java thread. _res = load_new_class_versions(Thread::current()); if (_res != JVMTI_ERROR_NONE) { // Free os::malloc allocated memory in load_new_class_version. os::free(_scratch_classes); RC_TIMER_STOP(_timer_vm_op_prologue); return false; } RC_TIMER_STOP(_timer_vm_op_prologue); return true; } void VM_RedefineClasses::doit() { Thread *thread = Thread::current(); if (UseSharedSpaces) { // Sharing is enabled so we remap the shared readonly space to // shared readwrite, private just in case we need to redefine // a shared class. We do the remap during the doit() phase of // the safepoint to be safer. if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) { RC_TRACE_WITH_THREAD(0x00000001, thread, ("failed to remap shared readonly space to readwrite, private")); _res = JVMTI_ERROR_INTERNAL; return; } } for (int i = 0; i < _class_count; i++) { redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread); } // Disable any dependent concurrent compilations SystemDictionary::notice_modification(); // Set flag indicating that some invariants are no longer true. // See jvmtiExport.hpp for detailed explanation. JvmtiExport::set_has_redefined_a_class(); #ifdef ASSERT SystemDictionary::classes_do(check_class, thread); #endif } void VM_RedefineClasses::doit_epilogue() { // Free os::malloc allocated memory. // The memory allocated in redefine will be free'ed in next VM operation. os::free(_scratch_classes); if (RC_TRACE_ENABLED(0x00000004)) { // Used to have separate timers for "doit" and "all", but the timer // overhead skewed the measurements. jlong doit_time = _timer_rsc_phase1.milliseconds() + _timer_rsc_phase2.milliseconds(); jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time; RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time, _timer_vm_op_prologue.milliseconds(), doit_time)); RC_TRACE(0x00000004, ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT, _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds())); } } bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) { // classes for primitives cannot be redefined if (java_lang_Class::is_primitive(klass_mirror)) { return false; } klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror); // classes for arrays cannot be redefined if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) { return false; } return true; } // Append the current entry at scratch_i in scratch_cp to *merge_cp_p // where the end of *merge_cp_p is specified by *merge_cp_length_p. For // direct CP entries, there is just the current entry to append. For // indirect and double-indirect CP entries, there are zero or more // referenced CP entries along with the current entry to append. // Indirect and double-indirect CP entries are handled by recursive // calls to append_entry() as needed. The referenced CP entries are // always appended to *merge_cp_p before the referee CP entry. These // referenced CP entries may already exist in *merge_cp_p in which case // there is nothing extra to append and only the current entry is // appended. void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp, int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { // append is different depending on entry tag type switch (scratch_cp->tag_at(scratch_i).value()) { // The old verifier is implemented outside the VM. It loads classes, // but does not resolve constant pool entries directly so we never // see Class entries here with the old verifier. Similarly the old // verifier does not like Class entries in the input constant pool. // The split-verifier is implemented in the VM so it can optionally // and directly resolve constant pool entries to load classes. The // split-verifier can accept either Class entries or UnresolvedClass // entries in the input constant pool. We revert the appended copy // back to UnresolvedClass so that either verifier will be happy // with the constant pool entry. case JVM_CONSTANT_Class: { // revert the copy to JVM_CONSTANT_UnresolvedClass (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p, scratch_cp->klass_name_at(scratch_i)); if (scratch_i != *merge_cp_length_p) { // The new entry in *merge_cp_p is at a different index than // the new entry in scratch_cp so we need to map the index values. map_index(scratch_cp, scratch_i, *merge_cp_length_p); } (*merge_cp_length_p)++; } break; // these are direct CP entries so they can be directly appended, // but double and long take two constant pool entries case JVM_CONSTANT_Double: // fall through case JVM_CONSTANT_Long: { constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, THREAD); if (scratch_i != *merge_cp_length_p) { // The new entry in *merge_cp_p is at a different index than // the new entry in scratch_cp so we need to map the index values. map_index(scratch_cp, scratch_i, *merge_cp_length_p); } (*merge_cp_length_p) += 2; } break; // these are direct CP entries so they can be directly appended case JVM_CONSTANT_Float: // fall through case JVM_CONSTANT_Integer: // fall through case JVM_CONSTANT_Utf8: // fall through // This was an indirect CP entry, but it has been changed into // an interned string so this entry can be directly appended. case JVM_CONSTANT_String: // fall through // These were indirect CP entries, but they have been changed into // Symbol*s so these entries can be directly appended. case JVM_CONSTANT_UnresolvedClass: // fall through case JVM_CONSTANT_UnresolvedString: { constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, THREAD); if (scratch_i != *merge_cp_length_p) { // The new entry in *merge_cp_p is at a different index than // the new entry in scratch_cp so we need to map the index values. map_index(scratch_cp, scratch_i, *merge_cp_length_p); } (*merge_cp_length_p)++; } break; // this is an indirect CP entry so it needs special handling case JVM_CONSTANT_NameAndType: { int name_ref_i = scratch_cp->name_ref_index_at(scratch_i); int new_name_ref_i = 0; bool match = (name_ref_i < *merge_cp_length_p) && scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i, THREAD); if (!match) { // forward reference in *merge_cp_p or not a direct match int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p, THREAD); if (found_i != 0) { guarantee(found_i != name_ref_i, "compare_entry_to() and find_matching_entry() do not agree"); // Found a matching entry somewhere else in *merge_cp_p so // just need a mapping entry. new_name_ref_i = found_i; map_index(scratch_cp, name_ref_i, found_i); } else { // no match found so we have to append this entry to *merge_cp_p append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p, THREAD); // The above call to append_entry() can only append one entry // so the post call query of *merge_cp_length_p is only for // the sake of consistency. new_name_ref_i = *merge_cp_length_p - 1; } } int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i); int new_signature_ref_i = 0; match = (signature_ref_i < *merge_cp_length_p) && scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p, signature_ref_i, THREAD); if (!match) { // forward reference in *merge_cp_p or not a direct match int found_i = scratch_cp->find_matching_entry(signature_ref_i, *merge_cp_p, THREAD); if (found_i != 0) { guarantee(found_i != signature_ref_i, "compare_entry_to() and find_matching_entry() do not agree"); // Found a matching entry somewhere else in *merge_cp_p so // just need a mapping entry. new_signature_ref_i = found_i; map_index(scratch_cp, signature_ref_i, found_i); } else { // no match found so we have to append this entry to *merge_cp_p append_entry(scratch_cp, signature_ref_i, merge_cp_p, merge_cp_length_p, THREAD); // The above call to append_entry() can only append one entry // so the post call query of *merge_cp_length_p is only for // the sake of consistency. new_signature_ref_i = *merge_cp_length_p - 1; } } // If the referenced entries already exist in *merge_cp_p, then // both new_name_ref_i and new_signature_ref_i will both be 0. // In that case, all we are appending is the current entry. if (new_name_ref_i == 0) { new_name_ref_i = name_ref_i; } else { RC_TRACE(0x00080000, ("NameAndType entry@%d name_ref_index change: %d to %d", *merge_cp_length_p, name_ref_i, new_name_ref_i)); } if (new_signature_ref_i == 0) { new_signature_ref_i = signature_ref_i; } else { RC_TRACE(0x00080000, ("NameAndType entry@%d signature_ref_index change: %d to %d", *merge_cp_length_p, signature_ref_i, new_signature_ref_i)); } (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p, new_name_ref_i, new_signature_ref_i); if (scratch_i != *merge_cp_length_p) { // The new entry in *merge_cp_p is at a different index than // the new entry in scratch_cp so we need to map the index values. map_index(scratch_cp, scratch_i, *merge_cp_length_p); } (*merge_cp_length_p)++; } break; // this is a double-indirect CP entry so it needs special handling case JVM_CONSTANT_Fieldref: // fall through case JVM_CONSTANT_InterfaceMethodref: // fall through case JVM_CONSTANT_Methodref: { int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i); int new_klass_ref_i = 0; bool match = (klass_ref_i < *merge_cp_length_p) && scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i, THREAD); if (!match) { // forward reference in *merge_cp_p or not a direct match int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p, THREAD); if (found_i != 0) { guarantee(found_i != klass_ref_i, "compare_entry_to() and find_matching_entry() do not agree"); // Found a matching entry somewhere else in *merge_cp_p so // just need a mapping entry. new_klass_ref_i = found_i; map_index(scratch_cp, klass_ref_i, found_i); } else { // no match found so we have to append this entry to *merge_cp_p append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p, THREAD); // The above call to append_entry() can only append one entry // so the post call query of *merge_cp_length_p is only for // the sake of consistency. Without the optimization where we // use JVM_CONSTANT_UnresolvedClass, then up to two entries // could be appended. new_klass_ref_i = *merge_cp_length_p - 1; } } int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i); int new_name_and_type_ref_i = 0; match = (name_and_type_ref_i < *merge_cp_length_p) && scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p, name_and_type_ref_i, THREAD); if (!match) { // forward reference in *merge_cp_p or not a direct match int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i, *merge_cp_p, THREAD); if (found_i != 0) { guarantee(found_i != name_and_type_ref_i, "compare_entry_to() and find_matching_entry() do not agree"); // Found a matching entry somewhere else in *merge_cp_p so // just need a mapping entry. new_name_and_type_ref_i = found_i; map_index(scratch_cp, name_and_type_ref_i, found_i); } else { // no match found so we have to append this entry to *merge_cp_p append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p, merge_cp_length_p, THREAD); // The above call to append_entry() can append more than // one entry so the post call query of *merge_cp_length_p // is required in order to get the right index for the // JVM_CONSTANT_NameAndType entry. new_name_and_type_ref_i = *merge_cp_length_p - 1; } } // If the referenced entries already exist in *merge_cp_p, then // both new_klass_ref_i and new_name_and_type_ref_i will both be // 0. In that case, all we are appending is the current entry. if (new_klass_ref_i == 0) { new_klass_ref_i = klass_ref_i; } if (new_name_and_type_ref_i == 0) { new_name_and_type_ref_i = name_and_type_ref_i; } const char *entry_name; switch (scratch_cp->tag_at(scratch_i).value()) { case JVM_CONSTANT_Fieldref: entry_name = "Fieldref"; (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i, new_name_and_type_ref_i); break; case JVM_CONSTANT_InterfaceMethodref: entry_name = "IFMethodref"; (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p, new_klass_ref_i, new_name_and_type_ref_i); break; case JVM_CONSTANT_Methodref: entry_name = "Methodref"; (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i, new_name_and_type_ref_i); break; default: guarantee(false, "bad switch"); break; } if (klass_ref_i != new_klass_ref_i) { RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i)); } if (name_and_type_ref_i != new_name_and_type_ref_i) { RC_TRACE(0x00080000, ("%s entry@%d name_and_type_index changed: %d to %d", entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i)); } if (scratch_i != *merge_cp_length_p) { // The new entry in *merge_cp_p is at a different index than // the new entry in scratch_cp so we need to map the index values. map_index(scratch_cp, scratch_i, *merge_cp_length_p); } (*merge_cp_length_p)++; } break; // At this stage, Class or UnresolvedClass could be here, but not // ClassIndex case JVM_CONSTANT_ClassIndex: // fall through // Invalid is used as the tag for the second constant pool entry // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should // not be seen by itself. case JVM_CONSTANT_Invalid: // fall through // At this stage, String or UnresolvedString could be here, but not // StringIndex case JVM_CONSTANT_StringIndex: // fall through // At this stage JVM_CONSTANT_UnresolvedClassInError should not be // here case JVM_CONSTANT_UnresolvedClassInError: // fall through default: { // leave a breadcrumb jbyte bad_value = scratch_cp->tag_at(scratch_i).value(); ShouldNotReachHere(); } break; } // end switch tag value } // end append_entry() void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) { typeArrayOop save; save = scratch_class->get_method_annotations_of(i); scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j)); scratch_class->set_method_annotations_of(j, save); save = scratch_class->get_method_parameter_annotations_of(i); scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j)); scratch_class->set_method_parameter_annotations_of(j, save); save = scratch_class->get_method_default_annotations_of(i); scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j)); scratch_class->set_method_default_annotations_of(j, save); } jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions( instanceKlassHandle the_class, instanceKlassHandle scratch_class) { int i; // Check superclasses, or rather their names, since superclasses themselves can be // requested to replace. // Check for NULL superclass first since this might be java.lang.Object if (the_class->super() != scratch_class->super() && (the_class->super() == NULL || scratch_class->super() == NULL || Klass::cast(the_class->super())->name() != Klass::cast(scratch_class->super())->name())) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; } // Check if the number, names and order of directly implemented interfaces are the same. // I think in principle we should just check if the sets of names of directly implemented // interfaces are the same, i.e. the order of declaration (which, however, if changed in the // .java file, also changes in .class file) should not matter. However, comparing sets is // technically a bit more difficult, and, more importantly, I am not sure at present that the // order of interfaces does not matter on the implementation level, i.e. that the VM does not // rely on it somewhere. objArrayOop k_interfaces = the_class->local_interfaces(); objArrayOop k_new_interfaces = scratch_class->local_interfaces(); int n_intfs = k_interfaces->length(); if (n_intfs != k_new_interfaces->length()) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; } for (i = 0; i < n_intfs; i++) { if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() != Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; } } // Check whether class is in the error init state. if (the_class->is_in_error_state()) { // TBD #5057930: special error code is needed in 1.6 return JVMTI_ERROR_INVALID_CLASS; } // Check whether class modifiers are the same. jushort old_flags = (jushort) the_class->access_flags().get_flags(); jushort new_flags = (jushort) scratch_class->access_flags().get_flags(); if (old_flags != new_flags) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED; } // Check if the number, names, types and order of fields declared in these classes // are the same. typeArrayOop k_old_fields = the_class->fields(); typeArrayOop k_new_fields = scratch_class->fields(); int n_fields = k_old_fields->length(); if (n_fields != k_new_fields->length()) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; } for (i = 0; i < n_fields; i += instanceKlass::next_offset) { // access old_flags = k_old_fields->ushort_at(i + instanceKlass::access_flags_offset); new_flags = k_new_fields->ushort_at(i + instanceKlass::access_flags_offset); if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; } // offset if (k_old_fields->short_at(i + instanceKlass::low_offset) != k_new_fields->short_at(i + instanceKlass::low_offset) || k_old_fields->short_at(i + instanceKlass::high_offset) != k_new_fields->short_at(i + instanceKlass::high_offset)) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; } // name and signature jshort name_index = k_old_fields->short_at(i + instanceKlass::name_index_offset); jshort sig_index = k_old_fields->short_at(i +instanceKlass::signature_index_offset); Symbol* name_sym1 = the_class->constants()->symbol_at(name_index); Symbol* sig_sym1 = the_class->constants()->symbol_at(sig_index); name_index = k_new_fields->short_at(i + instanceKlass::name_index_offset); sig_index = k_new_fields->short_at(i + instanceKlass::signature_index_offset); Symbol* name_sym2 = scratch_class->constants()->symbol_at(name_index); Symbol* sig_sym2 = scratch_class->constants()->symbol_at(sig_index); if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; } } // Do a parallel walk through the old and new methods. Detect // cases where they match (exist in both), have been added in // the new methods, or have been deleted (exist only in the // old methods). The class file parser places methods in order // by method name, but does not order overloaded methods by // signature. In order to determine what fate befell the methods, // this code places the overloaded new methods that have matching // old methods in the same order as the old methods and places // new overloaded methods at the end of overloaded methods of // that name. The code for this order normalization is adapted // from the algorithm used in instanceKlass::find_method(). // Since we are swapping out of order entries as we find them, // we only have to search forward through the overloaded methods. // Methods which are added and have the same name as an existing // method (but different signature) will be put at the end of // the methods with that name, and the name mismatch code will // handle them. objArrayHandle k_old_methods(the_class->methods()); objArrayHandle k_new_methods(scratch_class->methods()); int n_old_methods = k_old_methods->length(); int n_new_methods = k_new_methods->length(); int ni = 0; int oi = 0; while (true) { methodOop k_old_method; methodOop k_new_method; enum { matched, added, deleted, undetermined } method_was = undetermined; if (oi >= n_old_methods) { if (ni >= n_new_methods) { break; // we've looked at everything, done } // New method at the end k_new_method = (methodOop) k_new_methods->obj_at(ni); method_was = added; } else if (ni >= n_new_methods) { // Old method, at the end, is deleted k_old_method = (methodOop) k_old_methods->obj_at(oi); method_was = deleted; } else { // There are more methods in both the old and new lists k_old_method = (methodOop) k_old_methods->obj_at(oi); k_new_method = (methodOop) k_new_methods->obj_at(ni); if (k_old_method->name() != k_new_method->name()) { // Methods are sorted by method name, so a mismatch means added // or deleted if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) { method_was = added; } else { method_was = deleted; } } else if (k_old_method->signature() == k_new_method->signature()) { // Both the name and signature match method_was = matched; } else { // The name matches, but the signature doesn't, which means we have to // search forward through the new overloaded methods. int nj; // outside the loop for post-loop check for (nj = ni + 1; nj < n_new_methods; nj++) { methodOop m = (methodOop)k_new_methods->obj_at(nj); if (k_old_method->name() != m->name()) { // reached another method name so no more overloaded methods method_was = deleted; break; } if (k_old_method->signature() == m->signature()) { // found a match so swap the methods k_new_methods->obj_at_put(ni, m); k_new_methods->obj_at_put(nj, k_new_method); k_new_method = m; method_was = matched; break; } } if (nj >= n_new_methods) { // reached the end without a match; so method was deleted method_was = deleted; } } } switch (method_was) { case matched: // methods match, be sure modifiers do too old_flags = (jushort) k_old_method->access_flags().get_flags(); new_flags = (jushort) k_new_method->access_flags().get_flags(); if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) { return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED; } { u2 new_num = k_new_method->method_idnum(); u2 old_num = k_old_method->method_idnum(); if (new_num != old_num) { methodOop idnum_owner = scratch_class->method_with_idnum(old_num); if (idnum_owner != NULL) { // There is already a method assigned this idnum -- switch them idnum_owner->set_method_idnum(new_num); } k_new_method->set_method_idnum(old_num); swap_all_method_annotations(old_num, new_num, scratch_class); } } RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi)); // advance to next pair of methods ++oi; ++ni; break; case added: // method added, see if it is OK new_flags = (jushort) k_new_method->access_flags().get_flags(); if ((new_flags & JVM_ACC_PRIVATE) == 0 // hack: private should be treated as final, but alas || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 ) { // new methods must be private return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; } { u2 num = the_class->next_method_idnum(); if (num == constMethodOopDesc::UNSET_IDNUM) { // cannot add any more methods return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; } u2 new_num = k_new_method->method_idnum(); methodOop idnum_owner = scratch_class->method_with_idnum(num); if (idnum_owner != NULL) { // There is already a method assigned this idnum -- switch them idnum_owner->set_method_idnum(new_num); } k_new_method->set_method_idnum(num); swap_all_method_annotations(new_num, num, scratch_class); } RC_TRACE(0x00008000, ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni)); ++ni; // advance to next new method break; case deleted: // method deleted, see if it is OK old_flags = (jushort) k_old_method->access_flags().get_flags(); if ((old_flags & JVM_ACC_PRIVATE) == 0 // hack: private should be treated as final, but alas || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 ) { // deleted methods must be private return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED; } RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi)); ++oi; // advance to next old method break; default: ShouldNotReachHere(); } } return JVMTI_ERROR_NONE; } // Find new constant pool index value for old constant pool index value // by seaching the index map. Returns zero (0) if there is no mapped // value for the old constant pool index. int VM_RedefineClasses::find_new_index(int old_index) { if (_index_map_count == 0) { // map is empty so nothing can be found return 0; } if (old_index < 1 || old_index >= _index_map_p->length()) { // The old_index is out of range so it is not mapped. This should // not happen in regular constant pool merging use, but it can // happen if a corrupt annotation is processed. return 0; } int value = _index_map_p->at(old_index); if (value == -1) { // the old_index is not mapped return 0; } return value; } // end find_new_index() // Returns true if the current mismatch is due to a resolved/unresolved // class pair. Otherwise, returns false. bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1, int index1, constantPoolHandle cp2, int index2) { jbyte t1 = cp1->tag_at(index1).value(); if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) { return false; // wrong entry type; not our special case } jbyte t2 = cp2->tag_at(index2).value(); if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) { return false; // wrong entry type; not our special case } if (t1 == t2) { return false; // not a mismatch; not our special case } char *s1 = cp1->klass_name_at(index1)->as_C_string(); char *s2 = cp2->klass_name_at(index2)->as_C_string(); if (strcmp(s1, s2) != 0) { return false; // strings don't match; not our special case } return true; // made it through the gauntlet; this is our special case } // end is_unresolved_class_mismatch() // Returns true if the current mismatch is due to a resolved/unresolved // string pair. Otherwise, returns false. bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1, int index1, constantPoolHandle cp2, int index2) { jbyte t1 = cp1->tag_at(index1).value(); if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) { return false; // wrong entry type; not our special case } jbyte t2 = cp2->tag_at(index2).value(); if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) { return false; // wrong entry type; not our special case } if (t1 == t2) { return false; // not a mismatch; not our special case } char *s1 = cp1->string_at_noresolve(index1); char *s2 = cp2->string_at_noresolve(index2); if (strcmp(s1, s2) != 0) { return false; // strings don't match; not our special case } return true; // made it through the gauntlet; this is our special case } // end is_unresolved_string_mismatch() jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) { // For consistency allocate memory using os::malloc wrapper. _scratch_classes = (instanceKlassHandle *) os::malloc(sizeof(instanceKlassHandle) * _class_count); if (_scratch_classes == NULL) { return JVMTI_ERROR_OUT_OF_MEMORY; } ResourceMark rm(THREAD); 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 do a RedefineClasses guarantee(state != NULL, "exiting thread calling load_new_class_versions"); for (int i = 0; i < _class_count; i++) { oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass); // classes for primitives cannot be redefined if (!is_modifiable_class(mirror)) { return JVMTI_ERROR_UNMODIFIABLE_CLASS; } klassOop the_class_oop = java_lang_Class::as_klassOop(mirror); instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); Symbol* the_class_sym = the_class->name(); // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000001, THREAD, ("loading name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10)); ClassFileStream st((u1*) _class_defs[i].class_bytes, _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__"); // Parse the stream. Handle the_class_loader(THREAD, the_class->class_loader()); Handle protection_domain(THREAD, the_class->protection_domain()); // Set redefined class handle in JvmtiThreadState class. // This redefined class is sent to agent event handler for class file // load hook event. state->set_class_being_redefined(&the_class, _class_load_kind); klassOop k = SystemDictionary::parse_stream(the_class_sym, the_class_loader, protection_domain, &st, THREAD); // Clear class_being_redefined just to be sure. state->clear_class_being_redefined(); // TODO: if this is retransform, and nothing changed we can skip it instanceKlassHandle scratch_class (THREAD, k); if (HAS_PENDING_EXCEPTION) { Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'", ex_name->as_C_string())); CLEAR_PENDING_EXCEPTION; if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) { return JVMTI_ERROR_UNSUPPORTED_VERSION; } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) { return JVMTI_ERROR_INVALID_CLASS_FORMAT; } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) { return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION; } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) { // The message will be "XXX (wrong name: YYY)" return JVMTI_ERROR_NAMES_DONT_MATCH; } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { return JVMTI_ERROR_OUT_OF_MEMORY; } else { // Just in case more exceptions can be thrown.. return JVMTI_ERROR_FAILS_VERIFICATION; } } // Ensure class is linked before redefine if (!the_class->is_linked()) { the_class->link_class(THREAD); if (HAS_PENDING_EXCEPTION) { Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'", ex_name->as_C_string())); CLEAR_PENDING_EXCEPTION; if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { return JVMTI_ERROR_OUT_OF_MEMORY; } else { return JVMTI_ERROR_INTERNAL; } } } // Do the validity checks in compare_and_normalize_class_versions() // before verifying the byte codes. By doing these checks first, we // limit the number of functions that require redirection from // the_class to scratch_class. In particular, we don't have to // modify JNI GetSuperclass() and thus won't change its performance. jvmtiError res = compare_and_normalize_class_versions(the_class, scratch_class); if (res != JVMTI_ERROR_NONE) { return res; } // verify what the caller passed us { // The bug 6214132 caused the verification to fail. // Information about the_class and scratch_class is temporarily // recorded into jvmtiThreadState. This data is used to redirect // the_class to scratch_class in the JVM_* functions called by the // verifier. Please, refer to jvmtiThreadState.hpp for the detailed // description. RedefineVerifyMark rvm(&the_class, &scratch_class, state); Verifier::verify( scratch_class, Verifier::ThrowException, true, THREAD); } if (HAS_PENDING_EXCEPTION) { Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("verify_byte_codes exception: '%s'", ex_name->as_C_string())); CLEAR_PENDING_EXCEPTION; if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { return JVMTI_ERROR_OUT_OF_MEMORY; } else { // tell the caller the bytecodes are bad return JVMTI_ERROR_FAILS_VERIFICATION; } } res = merge_cp_and_rewrite(the_class, scratch_class, THREAD); if (res != JVMTI_ERROR_NONE) { return res; } if (VerifyMergedCPBytecodes) { // verify what we have done during constant pool merging { RedefineVerifyMark rvm(&the_class, &scratch_class, state); Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD); } if (HAS_PENDING_EXCEPTION) { Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string())); CLEAR_PENDING_EXCEPTION; if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { return JVMTI_ERROR_OUT_OF_MEMORY; } else { // tell the caller that constant pool merging screwed up return JVMTI_ERROR_INTERNAL; } } } Rewriter::rewrite(scratch_class, THREAD); if (HAS_PENDING_EXCEPTION) { Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); CLEAR_PENDING_EXCEPTION; if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { return JVMTI_ERROR_OUT_OF_MEMORY; } else { return JVMTI_ERROR_INTERNAL; } } _scratch_classes[i] = scratch_class; // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000001, THREAD, ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10)); } return JVMTI_ERROR_NONE; } // Map old_index to new_index as needed. scratch_cp is only needed // for RC_TRACE() calls. void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp, int old_index, int new_index) { if (find_new_index(old_index) != 0) { // old_index is already mapped return; } if (old_index == new_index) { // no mapping is needed return; } _index_map_p->at_put(old_index, new_index); _index_map_count++; RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index)); } // end map_index() // Merge old_cp and scratch_cp and return the results of the merge via // merge_cp_p. The number of entries in *merge_cp_p is returned via // merge_cp_length_p. The entries in old_cp occupy the same locations // in *merge_cp_p. Also creates a map of indices from entries in // scratch_cp to the corresponding entry in *merge_cp_p. Index map // entries are only created for entries in scratch_cp that occupy a // different location in *merged_cp_p. bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp, constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { if (merge_cp_p == NULL) { assert(false, "caller must provide scatch constantPool"); return false; // robustness } if (merge_cp_length_p == NULL) { assert(false, "caller must provide scatch CP length"); return false; // robustness } // Worst case we need old_cp->length() + scratch_cp()->length(), // but the caller might be smart so make sure we have at least // the minimum. if ((*merge_cp_p)->length() < old_cp->length()) { assert(false, "merge area too small"); return false; // robustness } RC_TRACE_WITH_THREAD(0x00010000, THREAD, ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length())); { // Pass 0: // The old_cp is copied to *merge_cp_p; this means that any code // using old_cp does not have to change. This work looks like a // perfect fit for constantPoolOop::copy_cp_to(), but we need to // handle one special case: // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass // This will make verification happy. int old_i; // index into old_cp // index zero (0) is not used in constantPools for (old_i = 1; old_i < old_cp->length(); old_i++) { // leave debugging crumb jbyte old_tag = old_cp->tag_at(old_i).value(); switch (old_tag) { case JVM_CONSTANT_Class: // revert the copy to JVM_CONSTANT_UnresolvedClass (*merge_cp_p)->unresolved_klass_at_put(old_i, old_cp->klass_name_at(old_i)); break; case JVM_CONSTANT_Double: case JVM_CONSTANT_Long: // just copy the entry to *merge_cp_p, but double and long take // two constant pool entries constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); old_i++; break; default: // just copy the entry to *merge_cp_p constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); break; } } // end for each old_cp entry // We don't need to sanity check that *merge_cp_length_p is within // *merge_cp_p bounds since we have the minimum on-entry check above. (*merge_cp_length_p) = old_i; } // merge_cp_len should be the same as old_cp->length() at this point // so this trace message is really a "warm-and-breathing" message. RC_TRACE_WITH_THREAD(0x00020000, THREAD, ("after pass 0: merge_cp_len=%d", *merge_cp_length_p)); int scratch_i; // index into scratch_cp { // Pass 1a: // Compare scratch_cp entries to the old_cp entries that we have // already copied to *merge_cp_p. In this pass, we are eliminating // exact duplicates (matching entry at same index) so we only // compare entries in the common indice range. int increment = 1; int pass1a_length = MIN2(old_cp->length(), scratch_cp->length()); for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) { switch (scratch_cp->tag_at(scratch_i).value()) { case JVM_CONSTANT_Double: case JVM_CONSTANT_Long: // double and long take two constant pool entries increment = 2; break; default: increment = 1; break; } bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i, CHECK_0); if (match) { // found a match at the same index so nothing more to do continue; } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i, *merge_cp_p, scratch_i)) { // The mismatch in compare_entry_to() above is because of a // resolved versus unresolved class entry at the same index // with the same string value. Since Pass 0 reverted any // class entries to unresolved class entries in *merge_cp_p, // we go with the unresolved class entry. continue; } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i, *merge_cp_p, scratch_i)) { // The mismatch in compare_entry_to() above is because of a // resolved versus unresolved string entry at the same index // with the same string value. We can live with whichever // happens to be at scratch_i in *merge_cp_p. continue; } int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0); if (found_i != 0) { guarantee(found_i != scratch_i, "compare_entry_to() and find_matching_entry() do not agree"); // Found a matching entry somewhere else in *merge_cp_p so // just need a mapping entry. map_index(scratch_cp, scratch_i, found_i); continue; } // The find_matching_entry() call above could fail to find a match // due to a resolved versus unresolved class or string entry situation // like we solved above with the is_unresolved_*_mismatch() calls. // However, we would have to call is_unresolved_*_mismatch() over // all of *merge_cp_p (potentially) and that doesn't seem to be // worth the time. // No match found so we have to append this entry and any unique // referenced entries to *merge_cp_p. append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, CHECK_0); } } RC_TRACE_WITH_THREAD(0x00020000, THREAD, ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", *merge_cp_length_p, scratch_i, _index_map_count)); if (scratch_i < scratch_cp->length()) { // Pass 1b: // old_cp is smaller than scratch_cp so there are entries in // scratch_cp that we have not yet processed. We take care of // those now. int increment = 1; for (; scratch_i < scratch_cp->length(); scratch_i += increment) { switch (scratch_cp->tag_at(scratch_i).value()) { case JVM_CONSTANT_Double: case JVM_CONSTANT_Long: // double and long take two constant pool entries increment = 2; break; default: increment = 1; break; } int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0); if (found_i != 0) { // Found a matching entry somewhere else in *merge_cp_p so // just need a mapping entry. map_index(scratch_cp, scratch_i, found_i); continue; } // No match found so we have to append this entry and any unique // referenced entries to *merge_cp_p. append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, CHECK_0); } RC_TRACE_WITH_THREAD(0x00020000, THREAD, ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", *merge_cp_length_p, scratch_i, _index_map_count)); } return true; } // end merge_constant_pools() // Merge constant pools between the_class and scratch_class and // potentially rewrite bytecodes in scratch_class to use the merged // constant pool. jvmtiError VM_RedefineClasses::merge_cp_and_rewrite( instanceKlassHandle the_class, instanceKlassHandle scratch_class, TRAPS) { // worst case merged constant pool length is old and new combined int merge_cp_length = the_class->constants()->length() + scratch_class->constants()->length(); constantPoolHandle old_cp(THREAD, the_class->constants()); constantPoolHandle scratch_cp(THREAD, scratch_class->constants()); // Constant pools are not easily reused so we allocate a new one // each time. // merge_cp is created unsafe for concurrent GC processing. It // should be marked safe before discarding it because, even if // garbage. If it crosses a card boundary, it may be scanned // in order to find the start of the first complete object on the card. constantPoolHandle merge_cp(THREAD, oopFactory::new_constantPool(merge_cp_length, methodOopDesc::IsUnsafeConc, THREAD)); int orig_length = old_cp->orig_length(); if (orig_length == 0) { // This old_cp is an actual original constant pool. We save // the original length in the merged constant pool so that // merge_constant_pools() can be more efficient. If a constant // pool has a non-zero orig_length() value, then that constant // pool was created by a merge operation in RedefineClasses. merge_cp->set_orig_length(old_cp->length()); } else { // This old_cp is a merged constant pool from a previous // RedefineClasses() calls so just copy the orig_length() // value. merge_cp->set_orig_length(old_cp->orig_length()); } ResourceMark rm(THREAD); _index_map_count = 0; _index_map_p = new intArray(scratch_cp->length(), -1); bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp, &merge_cp_length, THREAD); if (!result) { // The merge can fail due to memory allocation failure or due // to robustness checks. return JVMTI_ERROR_INTERNAL; } RC_TRACE_WITH_THREAD(0x00010000, THREAD, ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count)); if (_index_map_count == 0) { // there is nothing to map between the new and merged constant pools if (old_cp->length() == scratch_cp->length()) { // The old and new constant pools are the same length and the // index map is empty. This means that the three constant pools // are equivalent (but not the same). Unfortunately, the new // constant pool has not gone through link resolution nor have // the new class bytecodes gone through constant pool cache // rewriting so we can't use the old constant pool with the new // class. merge_cp()->set_is_conc_safe(true); merge_cp = constantPoolHandle(); // toss the merged constant pool } else if (old_cp->length() < scratch_cp->length()) { // The old constant pool has fewer entries than the new constant // pool and the index map is empty. This means the new constant // pool is a superset of the old constant pool. However, the old // class bytecodes have already gone through constant pool cache // rewriting so we can't use the new constant pool with the old // class. merge_cp()->set_is_conc_safe(true); merge_cp = constantPoolHandle(); // toss the merged constant pool } else { // The old constant pool has more entries than the new constant // pool and the index map is empty. This means that both the old // and merged constant pools are supersets of the new constant // pool. // Replace the new constant pool with a shrunken copy of the // merged constant pool; the previous new constant pool will // get GCed. set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true, THREAD); // drop local ref to the merged constant pool merge_cp()->set_is_conc_safe(true); merge_cp = constantPoolHandle(); } } else { if (RC_TRACE_ENABLED(0x00040000)) { // don't want to loop unless we are tracing int count = 0; for (int i = 1; i < _index_map_p->length(); i++) { int value = _index_map_p->at(i); if (value != -1) { RC_TRACE_WITH_THREAD(0x00040000, THREAD, ("index_map[%d]: old=%d new=%d", count, i, value)); count++; } } } // We have entries mapped between the new and merged constant pools // so we have to rewrite some constant pool references. if (!rewrite_cp_refs(scratch_class, THREAD)) { return JVMTI_ERROR_INTERNAL; } // Replace the new constant pool with a shrunken copy of the // merged constant pool so now the rewritten bytecodes have // valid references; the previous new constant pool will get // GCed. set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true, THREAD); merge_cp()->set_is_conc_safe(true); } assert(old_cp()->is_conc_safe(), "Just checking"); assert(scratch_cp()->is_conc_safe(), "Just checking"); return JVMTI_ERROR_NONE; } // end merge_cp_and_rewrite() // Rewrite constant pool references in klass scratch_class. bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class, TRAPS) { // rewrite constant pool references in the methods: if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) { // propagate failure back to caller return false; } // rewrite constant pool references in the class_annotations: if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) { // propagate failure back to caller return false; } // rewrite constant pool references in the fields_annotations: if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) { // propagate failure back to caller return false; } // rewrite constant pool references in the methods_annotations: if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) { // propagate failure back to caller return false; } // rewrite constant pool references in the methods_parameter_annotations: if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class, THREAD)) { // propagate failure back to caller return false; } // rewrite constant pool references in the methods_default_annotations: if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class, THREAD)) { // propagate failure back to caller return false; } return true; } // end rewrite_cp_refs() // Rewrite constant pool references in the methods. bool VM_RedefineClasses::rewrite_cp_refs_in_methods( instanceKlassHandle scratch_class, TRAPS) { objArrayHandle methods(THREAD, scratch_class->methods()); if (methods.is_null() || methods->length() == 0) { // no methods so nothing to do return true; } // rewrite constant pool references in the methods: for (int i = methods->length() - 1; i >= 0; i--) { methodHandle method(THREAD, (methodOop)methods->obj_at(i)); methodHandle new_method; rewrite_cp_refs_in_method(method, &new_method, CHECK_false); if (!new_method.is_null()) { // the method has been replaced so save the new method version methods->obj_at_put(i, new_method()); } } return true; } // Rewrite constant pool references in the specific method. This code // was adapted from Rewriter::rewrite_method(). void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method, methodHandle *new_method_p, TRAPS) { *new_method_p = methodHandle(); // default is no new method // We cache a pointer to the bytecodes here in code_base. If GC // moves the methodOop, then the bytecodes will also move which // will likely cause a crash. We create a No_Safepoint_Verifier // object to detect whether we pass a possible safepoint in this // code block. No_Safepoint_Verifier nsv; // Bytecodes and their length address code_base = method->code_base(); int code_length = method->code_size(); int bc_length; for (int bci = 0; bci < code_length; bci += bc_length) { address bcp = code_base + bci; Bytecodes::Code c = (Bytecodes::Code)(*bcp); bc_length = Bytecodes::length_for(c); if (bc_length == 0) { // More complicated bytecodes report a length of zero so // we have to try again a slightly different way. bc_length = Bytecodes::length_at(method(), bcp); } assert(bc_length != 0, "impossible bytecode length"); switch (c) { case Bytecodes::_ldc: { int cp_index = *(bcp + 1); int new_index = find_new_index(cp_index); if (StressLdcRewrite && new_index == 0) { // If we are stressing ldc -> ldc_w rewriting, then we // always need a new_index value. new_index = cp_index; } if (new_index != 0) { // the original index is mapped so we have more work to do if (!StressLdcRewrite && new_index <= max_jubyte) { // The new value can still use ldc instead of ldc_w // unless we are trying to stress ldc -> ldc_w rewriting RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), bcp, cp_index, new_index)); *(bcp + 1) = new_index; } else { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), bcp, cp_index, new_index)); // the new value needs ldc_w instead of ldc u_char inst_buffer[4]; // max instruction size is 4 bytes bcp = (address)inst_buffer; // construct new instruction sequence *bcp = Bytecodes::_ldc_w; bcp++; // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w. // See comment below for difference between put_Java_u2() // and put_native_u2(). Bytes::put_Java_u2(bcp, new_index); Relocator rc(method, NULL /* no RelocatorListener needed */); methodHandle m; { Pause_No_Safepoint_Verifier pnsv(&nsv); // ldc is 2 bytes and ldc_w is 3 bytes m = rc.insert_space_at(bci, 3, inst_buffer, THREAD); if (m.is_null() || HAS_PENDING_EXCEPTION) { guarantee(false, "insert_space_at() failed"); } } // return the new method so that the caller can update // the containing class *new_method_p = method = m; // switch our bytecode processing loop from the old method // to the new method code_base = method->code_base(); code_length = method->code_size(); bcp = code_base + bci; c = (Bytecodes::Code)(*bcp); bc_length = Bytecodes::length_for(c); assert(bc_length != 0, "sanity check"); } // end we need ldc_w instead of ldc } // end if there is a mapped index } break; // these bytecodes have a two-byte constant pool index case Bytecodes::_anewarray : // fall through case Bytecodes::_checkcast : // fall through case Bytecodes::_getfield : // fall through case Bytecodes::_getstatic : // fall through case Bytecodes::_instanceof : // fall through case Bytecodes::_invokeinterface: // fall through case Bytecodes::_invokespecial : // fall through case Bytecodes::_invokestatic : // fall through case Bytecodes::_invokevirtual : // fall through case Bytecodes::_ldc_w : // fall through case Bytecodes::_ldc2_w : // fall through case Bytecodes::_multianewarray : // fall through case Bytecodes::_new : // fall through case Bytecodes::_putfield : // fall through case Bytecodes::_putstatic : { address p = bcp + 1; int cp_index = Bytes::get_Java_u2(p); int new_index = find_new_index(cp_index); if (new_index != 0) { // the original index is mapped so update w/ new value RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), bcp, cp_index, new_index)); // Rewriter::rewrite_method() uses put_native_u2() in this // situation because it is reusing the constant pool index // location for a native index into the constantPoolCache. // Since we are updating the constant pool index prior to // verification and constantPoolCache initialization, we // need to keep the new index in Java byte order. Bytes::put_Java_u2(p, new_index); } } break; } } // end for each bytecode } // end rewrite_cp_refs_in_method() // Rewrite constant pool references in the class_annotations field. bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations( instanceKlassHandle scratch_class, TRAPS) { typeArrayHandle class_annotations(THREAD, scratch_class->class_annotations()); if (class_annotations.is_null() || class_annotations->length() == 0) { // no class_annotations so nothing to do return true; } RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("class_annotations length=%d", class_annotations->length())); int byte_i = 0; // byte index into class_annotations return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i, THREAD); } // Rewrite constant pool references in an annotations typeArray. This // "structure" is adapted from the RuntimeVisibleAnnotations_attribute // that is described in section 4.8.15 of the 2nd-edition of the VM spec: // // annotations_typeArray { // u2 num_annotations; // annotation annotations[num_annotations]; // } // bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray( typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { if ((byte_i_ref + 2) > annotations_typeArray->length()) { // not enough room for num_annotations field RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for num_annotations field")); return false; } u2 num_annotations = Bytes::get_Java_u2((address) annotations_typeArray->byte_at_addr(byte_i_ref)); byte_i_ref += 2; RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_annotations=%d", num_annotations)); int calc_num_annotations = 0; for (; calc_num_annotations < num_annotations; calc_num_annotations++) { if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad annotation_struct at %d", calc_num_annotations)); // propagate failure back to caller return false; } } assert(num_annotations == calc_num_annotations, "sanity check"); return true; } // end rewrite_cp_refs_in_annotations_typeArray() // Rewrite constant pool references in the annotation struct portion of // an annotations_typeArray. This "structure" is from section 4.8.15 of // the 2nd-edition of the VM spec: // // struct annotation { // u2 type_index; // u2 num_element_value_pairs; // { // u2 element_name_index; // element_value value; // } element_value_pairs[num_element_value_pairs]; // } // bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct( typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) { // not enough room for smallest annotation_struct RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for annotation_struct")); return false; } u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray, byte_i_ref, "mapped old type_index=%d", THREAD); u2 num_element_value_pairs = Bytes::get_Java_u2((address) annotations_typeArray->byte_at_addr( byte_i_ref)); byte_i_ref += 2; RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs)); int calc_num_element_value_pairs = 0; for (; calc_num_element_value_pairs < num_element_value_pairs; calc_num_element_value_pairs++) { if ((byte_i_ref + 2) > annotations_typeArray->length()) { // not enough room for another element_name_index, let alone // the rest of another component RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for element_name_index")); return false; } u2 element_name_index = rewrite_cp_ref_in_annotation_data( annotations_typeArray, byte_i_ref, "mapped old element_name_index=%d", THREAD); RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("element_name_index=%d", element_name_index)); if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad element_value at %d", calc_num_element_value_pairs)); // propagate failure back to caller return false; } } // end for each component assert(num_element_value_pairs == calc_num_element_value_pairs, "sanity check"); return true; } // end rewrite_cp_refs_in_annotation_struct() // Rewrite a constant pool reference at the current position in // annotations_typeArray if needed. Returns the original constant // pool reference if a rewrite was not needed or the new constant // pool reference if a rewrite was needed. u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data( typeArrayHandle annotations_typeArray, int &byte_i_ref, const char * trace_mesg, TRAPS) { address cp_index_addr = (address) annotations_typeArray->byte_at_addr(byte_i_ref); u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr); u2 new_cp_index = find_new_index(old_cp_index); if (new_cp_index != 0) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index)); Bytes::put_Java_u2(cp_index_addr, new_cp_index); old_cp_index = new_cp_index; } byte_i_ref += 2; return old_cp_index; } // Rewrite constant pool references in the element_value portion of an // annotations_typeArray. This "structure" is from section 4.8.15.1 of // the 2nd-edition of the VM spec: // // struct element_value { // u1 tag; // union { // u2 const_value_index; // { // u2 type_name_index; // u2 const_name_index; // } enum_const_value; // u2 class_info_index; // annotation annotation_value; // struct { // u2 num_values; // element_value values[num_values]; // } array_value; // } value; // } // bool VM_RedefineClasses::rewrite_cp_refs_in_element_value( typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { if ((byte_i_ref + 1) > annotations_typeArray->length()) { // not enough room for a tag let alone the rest of an element_value RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for a tag")); return false; } u1 tag = annotations_typeArray->byte_at(byte_i_ref); byte_i_ref++; RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag)); switch (tag) { // These BaseType tag values are from Table 4.2 in VM spec: case 'B': // byte case 'C': // char case 'D': // double case 'F': // float case 'I': // int case 'J': // long case 'S': // short case 'Z': // boolean // The remaining tag values are from Table 4.8 in the 2nd-edition of // the VM spec: case 's': { // For the above tag values (including the BaseType values), // value.const_value_index is right union field. if ((byte_i_ref + 2) > annotations_typeArray->length()) { // not enough room for a const_value_index RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for a const_value_index")); return false; } u2 const_value_index = rewrite_cp_ref_in_annotation_data( annotations_typeArray, byte_i_ref, "mapped old const_value_index=%d", THREAD); RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("const_value_index=%d", const_value_index)); } break; case 'e': { // for the above tag value, value.enum_const_value is right union field if ((byte_i_ref + 4) > annotations_typeArray->length()) { // not enough room for a enum_const_value RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for a enum_const_value")); return false; } u2 type_name_index = rewrite_cp_ref_in_annotation_data( annotations_typeArray, byte_i_ref, "mapped old type_name_index=%d", THREAD); u2 const_name_index = rewrite_cp_ref_in_annotation_data( annotations_typeArray, byte_i_ref, "mapped old const_name_index=%d", THREAD); RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index)); } break; case 'c': { // for the above tag value, value.class_info_index is right union field if ((byte_i_ref + 2) > annotations_typeArray->length()) { // not enough room for a class_info_index RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for a class_info_index")); return false; } u2 class_info_index = rewrite_cp_ref_in_annotation_data( annotations_typeArray, byte_i_ref, "mapped old class_info_index=%d", THREAD); RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("class_info_index=%d", class_info_index)); } break; case '@': // For the above tag value, value.attr_value is the right union // field. This is a nested annotation. if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref, THREAD)) { // propagate failure back to caller return false; } break; case '[': { if ((byte_i_ref + 2) > annotations_typeArray->length()) { // not enough room for a num_values field RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for a num_values field")); return false; } // For the above tag value, value.array_value is the right union // field. This is an array of nested element_value. u2 num_values = Bytes::get_Java_u2((address) annotations_typeArray->byte_at_addr(byte_i_ref)); byte_i_ref += 2; RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values)); int calc_num_values = 0; for (; calc_num_values < num_values; calc_num_values++) { if (!rewrite_cp_refs_in_element_value( annotations_typeArray, byte_i_ref, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad nested element_value at %d", calc_num_values)); // propagate failure back to caller return false; } } assert(num_values == calc_num_values, "sanity check"); } break; default: RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag)); return false; } // end decode tag field return true; } // end rewrite_cp_refs_in_element_value() // Rewrite constant pool references in a fields_annotations field. bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations( instanceKlassHandle scratch_class, TRAPS) { objArrayHandle fields_annotations(THREAD, scratch_class->fields_annotations()); if (fields_annotations.is_null() || fields_annotations->length() == 0) { // no fields_annotations so nothing to do return true; } RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("fields_annotations length=%d", fields_annotations->length())); for (int i = 0; i < fields_annotations->length(); i++) { typeArrayHandle field_annotations(THREAD, (typeArrayOop)fields_annotations->obj_at(i)); if (field_annotations.is_null() || field_annotations->length() == 0) { // this field does not have any annotations so skip it continue; } int byte_i = 0; // byte index into field_annotations if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad field_annotations at %d", i)); // propagate failure back to caller return false; } } return true; } // end rewrite_cp_refs_in_fields_annotations() // Rewrite constant pool references in a methods_annotations field. bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations( instanceKlassHandle scratch_class, TRAPS) { objArrayHandle methods_annotations(THREAD, scratch_class->methods_annotations()); if (methods_annotations.is_null() || methods_annotations->length() == 0) { // no methods_annotations so nothing to do return true; } RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("methods_annotations length=%d", methods_annotations->length())); for (int i = 0; i < methods_annotations->length(); i++) { typeArrayHandle method_annotations(THREAD, (typeArrayOop)methods_annotations->obj_at(i)); if (method_annotations.is_null() || method_annotations->length() == 0) { // this method does not have any annotations so skip it continue; } int byte_i = 0; // byte index into method_annotations if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad method_annotations at %d", i)); // propagate failure back to caller return false; } } return true; } // end rewrite_cp_refs_in_methods_annotations() // Rewrite constant pool references in a methods_parameter_annotations // field. This "structure" is adapted from the // RuntimeVisibleParameterAnnotations_attribute described in section // 4.8.17 of the 2nd-edition of the VM spec: // // methods_parameter_annotations_typeArray { // u1 num_parameters; // { // u2 num_annotations; // annotation annotations[num_annotations]; // } parameter_annotations[num_parameters]; // } // bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations( instanceKlassHandle scratch_class, TRAPS) { objArrayHandle methods_parameter_annotations(THREAD, scratch_class->methods_parameter_annotations()); if (methods_parameter_annotations.is_null() || methods_parameter_annotations->length() == 0) { // no methods_parameter_annotations so nothing to do return true; } RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("methods_parameter_annotations length=%d", methods_parameter_annotations->length())); for (int i = 0; i < methods_parameter_annotations->length(); i++) { typeArrayHandle method_parameter_annotations(THREAD, (typeArrayOop)methods_parameter_annotations->obj_at(i)); if (method_parameter_annotations.is_null() || method_parameter_annotations->length() == 0) { // this method does not have any parameter annotations so skip it continue; } if (method_parameter_annotations->length() < 1) { // not enough room for a num_parameters field RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("length() is too small for a num_parameters field at %d", i)); return false; } int byte_i = 0; // byte index into method_parameter_annotations u1 num_parameters = method_parameter_annotations->byte_at(byte_i); byte_i++; RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_parameters=%d", num_parameters)); int calc_num_parameters = 0; for (; calc_num_parameters < num_parameters; calc_num_parameters++) { if (!rewrite_cp_refs_in_annotations_typeArray( method_parameter_annotations, byte_i, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad method_parameter_annotations at %d", calc_num_parameters)); // propagate failure back to caller return false; } } assert(num_parameters == calc_num_parameters, "sanity check"); } return true; } // end rewrite_cp_refs_in_methods_parameter_annotations() // Rewrite constant pool references in a methods_default_annotations // field. This "structure" is adapted from the AnnotationDefault_attribute // that is described in section 4.8.19 of the 2nd-edition of the VM spec: // // methods_default_annotations_typeArray { // element_value default_value; // } // bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations( instanceKlassHandle scratch_class, TRAPS) { objArrayHandle methods_default_annotations(THREAD, scratch_class->methods_default_annotations()); if (methods_default_annotations.is_null() || methods_default_annotations->length() == 0) { // no methods_default_annotations so nothing to do return true; } RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("methods_default_annotations length=%d", methods_default_annotations->length())); for (int i = 0; i < methods_default_annotations->length(); i++) { typeArrayHandle method_default_annotations(THREAD, (typeArrayOop)methods_default_annotations->obj_at(i)); if (method_default_annotations.is_null() || method_default_annotations->length() == 0) { // this method does not have any default annotations so skip it continue; } int byte_i = 0; // byte index into method_default_annotations if (!rewrite_cp_refs_in_element_value( method_default_annotations, byte_i, THREAD)) { RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad default element_value at %d", i)); // propagate failure back to caller return false; } } return true; } // end rewrite_cp_refs_in_methods_default_annotations() // Rewrite constant pool references in the method's stackmap table. // These "structures" are adapted from the StackMapTable_attribute that // is described in section 4.8.4 of the 6.0 version of the VM spec // (dated 2005.10.26): // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf // // stack_map { // u2 number_of_entries; // stack_map_frame entries[number_of_entries]; // } // void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table( methodHandle method, TRAPS) { if (!method->has_stackmap_table()) { return; } typeArrayOop stackmap_data = method->stackmap_data(); address stackmap_p = (address)stackmap_data->byte_at_addr(0); address stackmap_end = stackmap_p + stackmap_data->length(); assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries"); u2 number_of_entries = Bytes::get_Java_u2(stackmap_p); stackmap_p += 2; RC_TRACE_WITH_THREAD(0x04000000, THREAD, ("number_of_entries=%u", number_of_entries)); // walk through each stack_map_frame u2 calc_number_of_entries = 0; for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) { // The stack_map_frame structure is a u1 frame_type followed by // 0 or more bytes of data: // // union stack_map_frame { // same_frame; // same_locals_1_stack_item_frame; // same_locals_1_stack_item_frame_extended; // chop_frame; // same_frame_extended; // append_frame; // full_frame; // } assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type"); // The Linux compiler does not like frame_type to be u1 or u2. It // issues the following warning for the first if-statement below: // // "warning: comparison is always true due to limited range of data type" // u4 frame_type = *stackmap_p; stackmap_p++; // same_frame { // u1 frame_type = SAME; /* 0-63 */ // } if (frame_type >= 0 && frame_type <= 63) { // nothing more to do for same_frame } // same_locals_1_stack_item_frame { // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */ // verification_type_info stack[1]; // } else if (frame_type >= 64 && frame_type <= 127) { rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, calc_number_of_entries, frame_type, THREAD); } // reserved for future use else if (frame_type >= 128 && frame_type <= 246) { // nothing more to do for reserved frame_types } // same_locals_1_stack_item_frame_extended { // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */ // u2 offset_delta; // verification_type_info stack[1]; // } else if (frame_type == 247) { stackmap_p += 2; rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, calc_number_of_entries, frame_type, THREAD); } // chop_frame { // u1 frame_type = CHOP; /* 248-250 */ // u2 offset_delta; // } else if (frame_type >= 248 && frame_type <= 250) { stackmap_p += 2; } // same_frame_extended { // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/ // u2 offset_delta; // } else if (frame_type == 251) { stackmap_p += 2; } // append_frame { // u1 frame_type = APPEND; /* 252-254 */ // u2 offset_delta; // verification_type_info locals[frame_type - 251]; // } else if (frame_type >= 252 && frame_type <= 254) { assert(stackmap_p + 2 <= stackmap_end, "no room for offset_delta"); stackmap_p += 2; u1 len = frame_type - 251; for (u1 i = 0; i < len; i++) { rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, calc_number_of_entries, frame_type, THREAD); } } // full_frame { // u1 frame_type = FULL_FRAME; /* 255 */ // u2 offset_delta; // u2 number_of_locals; // verification_type_info locals[number_of_locals]; // u2 number_of_stack_items; // verification_type_info stack[number_of_stack_items]; // } else if (frame_type == 255) { assert(stackmap_p + 2 + 2 <= stackmap_end, "no room for smallest full_frame"); stackmap_p += 2; u2 number_of_locals = Bytes::get_Java_u2(stackmap_p); stackmap_p += 2; for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) { rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, calc_number_of_entries, frame_type, THREAD); } // Use the largest size for the number_of_stack_items, but only get // the right number of bytes. u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p); stackmap_p += 2; for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) { rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, calc_number_of_entries, frame_type, THREAD); } } } // end while there is a stack_map_frame assert(number_of_entries == calc_number_of_entries, "sanity check"); } // end rewrite_cp_refs_in_stack_map_table() // Rewrite constant pool references in the verification type info // portion of the method's stackmap table. These "structures" are // adapted from the StackMapTable_attribute that is described in // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26): // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf // // The verification_type_info structure is a u1 tag followed by 0 or // more bytes of data: // // union verification_type_info { // Top_variable_info; // Integer_variable_info; // Float_variable_info; // Long_variable_info; // Double_variable_info; // Null_variable_info; // UninitializedThis_variable_info; // Object_variable_info; // Uninitialized_variable_info; // } // void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info( address& stackmap_p_ref, address stackmap_end, u2 frame_i, u1 frame_type, TRAPS) { assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag"); u1 tag = *stackmap_p_ref; stackmap_p_ref++; switch (tag) { // Top_variable_info { // u1 tag = ITEM_Top; /* 0 */ // } // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top case 0: // fall through // Integer_variable_info { // u1 tag = ITEM_Integer; /* 1 */ // } case ITEM_Integer: // fall through // Float_variable_info { // u1 tag = ITEM_Float; /* 2 */ // } case ITEM_Float: // fall through // Double_variable_info { // u1 tag = ITEM_Double; /* 3 */ // } case ITEM_Double: // fall through // Long_variable_info { // u1 tag = ITEM_Long; /* 4 */ // } case ITEM_Long: // fall through // Null_variable_info { // u1 tag = ITEM_Null; /* 5 */ // } case ITEM_Null: // fall through // UninitializedThis_variable_info { // u1 tag = ITEM_UninitializedThis; /* 6 */ // } case ITEM_UninitializedThis: // nothing more to do for the above tag types break; // Object_variable_info { // u1 tag = ITEM_Object; /* 7 */ // u2 cpool_index; // } case ITEM_Object: { assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index"); u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref); u2 new_cp_index = find_new_index(cpool_index); if (new_cp_index != 0) { RC_TRACE_WITH_THREAD(0x04000000, THREAD, ("mapped old cpool_index=%d", cpool_index)); Bytes::put_Java_u2(stackmap_p_ref, new_cp_index); cpool_index = new_cp_index; } stackmap_p_ref += 2; RC_TRACE_WITH_THREAD(0x04000000, THREAD, ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index)); } break; // Uninitialized_variable_info { // u1 tag = ITEM_Uninitialized; /* 8 */ // u2 offset; // } case ITEM_Uninitialized: assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset"); stackmap_p_ref += 2; break; default: RC_TRACE_WITH_THREAD(0x04000000, THREAD, ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag)); ShouldNotReachHere(); break; } // end switch (tag) } // end rewrite_cp_refs_in_verification_type_info() // Change the constant pool associated with klass scratch_class to // scratch_cp. If shrink is true, then scratch_cp_length elements // are copied from scratch_cp to a smaller constant pool and the // smaller constant pool is associated with scratch_class. void VM_RedefineClasses::set_new_constant_pool( instanceKlassHandle scratch_class, constantPoolHandle scratch_cp, int scratch_cp_length, bool shrink, TRAPS) { assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check"); if (shrink) { // scratch_cp is a merged constant pool and has enough space for a // worst case merge situation. We want to associate the minimum // sized constant pool with the klass to save space. constantPoolHandle smaller_cp(THREAD, oopFactory::new_constantPool(scratch_cp_length, methodOopDesc::IsUnsafeConc, THREAD)); // preserve orig_length() value in the smaller copy int orig_length = scratch_cp->orig_length(); assert(orig_length != 0, "sanity check"); smaller_cp->set_orig_length(orig_length); scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD); scratch_cp = smaller_cp; smaller_cp()->set_is_conc_safe(true); } // attach new constant pool to klass scratch_cp->set_pool_holder(scratch_class()); // attach klass to new constant pool scratch_class->set_constants(scratch_cp()); int i; // for portability // update each field in klass to use new constant pool indices as needed typeArrayHandle fields(THREAD, scratch_class->fields()); int n_fields = fields->length(); for (i = 0; i < n_fields; i += instanceKlass::next_offset) { jshort cur_index = fields->short_at(i + instanceKlass::name_index_offset); jshort new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("field-name_index change: %d to %d", cur_index, new_index)); fields->short_at_put(i + instanceKlass::name_index_offset, new_index); } cur_index = fields->short_at(i + instanceKlass::signature_index_offset); new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("field-signature_index change: %d to %d", cur_index, new_index)); fields->short_at_put(i + instanceKlass::signature_index_offset, new_index); } cur_index = fields->short_at(i + instanceKlass::initval_index_offset); new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("field-initval_index change: %d to %d", cur_index, new_index)); fields->short_at_put(i + instanceKlass::initval_index_offset, new_index); } cur_index = fields->short_at(i + instanceKlass::generic_signature_offset); new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("field-generic_signature change: %d to %d", cur_index, new_index)); fields->short_at_put(i + instanceKlass::generic_signature_offset, new_index); } } // end for each field // Update constant pool indices in the inner classes info to use // new constant indices as needed. The inner classes info is a // quadruple: // (inner_class_info, outer_class_info, inner_name, inner_access_flags) typeArrayOop inner_class_list = scratch_class->inner_classes(); int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length(); if (icl_length > 0) { typeArrayHandle inner_class_list_h(THREAD, inner_class_list); for (int i = 0; i < icl_length; i += instanceKlass::inner_class_next_offset) { int cur_index = inner_class_list_h->ushort_at(i + instanceKlass::inner_class_inner_class_info_offset); if (cur_index == 0) { continue; // JVM spec. allows null inner class refs so skip it } int new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("inner_class_info change: %d to %d", cur_index, new_index)); inner_class_list_h->ushort_at_put(i + instanceKlass::inner_class_inner_class_info_offset, new_index); } cur_index = inner_class_list_h->ushort_at(i + instanceKlass::inner_class_outer_class_info_offset); new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("outer_class_info change: %d to %d", cur_index, new_index)); inner_class_list_h->ushort_at_put(i + instanceKlass::inner_class_outer_class_info_offset, new_index); } cur_index = inner_class_list_h->ushort_at(i + instanceKlass::inner_class_inner_name_offset); new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("inner_name change: %d to %d", cur_index, new_index)); inner_class_list_h->ushort_at_put(i + instanceKlass::inner_class_inner_name_offset, new_index); } } // end for each inner class } // end if we have inner classes // Attach each method in klass to the new constant pool and update // to use new constant pool indices as needed: objArrayHandle methods(THREAD, scratch_class->methods()); for (i = methods->length() - 1; i >= 0; i--) { methodHandle method(THREAD, (methodOop)methods->obj_at(i)); method->set_constants(scratch_cp()); int new_index = find_new_index(method->name_index()); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("method-name_index change: %d to %d", method->name_index(), new_index)); method->set_name_index(new_index); } new_index = find_new_index(method->signature_index()); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("method-signature_index change: %d to %d", method->signature_index(), new_index)); method->set_signature_index(new_index); } new_index = find_new_index(method->generic_signature_index()); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index)); method->set_generic_signature_index(new_index); } // Update constant pool indices in the method's checked exception // table to use new constant indices as needed. int cext_length = method->checked_exceptions_length(); if (cext_length > 0) { CheckedExceptionElement * cext_table = method->checked_exceptions_start(); for (int j = 0; j < cext_length; j++) { int cur_index = cext_table[j].class_cp_index; int new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("cext-class_cp_index change: %d to %d", cur_index, new_index)); cext_table[j].class_cp_index = (u2)new_index; } } // end for each checked exception table entry } // end if there are checked exception table entries // Update each catch type index in the method's exception table // to use new constant pool indices as needed. The exception table // holds quadruple entries of the form: // (beg_bci, end_bci, handler_bci, klass_index) const int beg_bci_offset = 0; const int end_bci_offset = 1; const int handler_bci_offset = 2; const int klass_index_offset = 3; const int entry_size = 4; typeArrayHandle ex_table (THREAD, method->exception_table()); int ext_length = ex_table->length(); assert(ext_length % entry_size == 0, "exception table format has changed"); for (int j = 0; j < ext_length; j += entry_size) { int cur_index = ex_table->int_at(j + klass_index_offset); int new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("ext-klass_index change: %d to %d", cur_index, new_index)); ex_table->int_at_put(j + klass_index_offset, new_index); } } // end for each exception table entry // Update constant pool indices in the method's local variable // table to use new constant indices as needed. The local variable // table hold sextuple entries of the form: // (start_pc, length, name_index, descriptor_index, signature_index, slot) int lvt_length = method->localvariable_table_length(); if (lvt_length > 0) { LocalVariableTableElement * lv_table = method->localvariable_table_start(); for (int j = 0; j < lvt_length; j++) { int cur_index = lv_table[j].name_cp_index; int new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("lvt-name_cp_index change: %d to %d", cur_index, new_index)); lv_table[j].name_cp_index = (u2)new_index; } cur_index = lv_table[j].descriptor_cp_index; new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index)); lv_table[j].descriptor_cp_index = (u2)new_index; } cur_index = lv_table[j].signature_cp_index; new_index = find_new_index(cur_index); if (new_index != 0) { RC_TRACE_WITH_THREAD(0x00080000, THREAD, ("lvt-signature_cp_index change: %d to %d", cur_index, new_index)); lv_table[j].signature_cp_index = (u2)new_index; } } // end for each local variable table entry } // end if there are local variable table entries rewrite_cp_refs_in_stack_map_table(method, THREAD); } // end for each method assert(scratch_cp()->is_conc_safe(), "Just checking"); } // end set_new_constant_pool() // Unevolving classes may point to methods of the_class directly // from their constant pool caches, itables, and/or vtables. We // use the SystemDictionary::classes_do() facility and this helper // to fix up these pointers. // // Note: We currently don't support updating the vtable in // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp. void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop, oop initiating_loader, TRAPS) { Klass *k = k_oop->klass_part(); if (k->oop_is_instance()) { HandleMark hm(THREAD); instanceKlass *ik = (instanceKlass *) k; // HotSpot specific optimization! HotSpot does not currently // support delegation from the bootstrap class loader to a // user-defined class loader. This means that if the bootstrap // class loader is the initiating class loader, then it will also // be the defining class loader. This also means that classes // loaded by the bootstrap class loader cannot refer to classes // loaded by a user-defined class loader. Note: a user-defined // class loader can delegate to the bootstrap class loader. // // If the current class being redefined has a user-defined class // loader as its defining class loader, then we can skip all // classes loaded by the bootstrap class loader. bool is_user_defined = instanceKlass::cast(_the_class_oop)->class_loader() != NULL; if (is_user_defined && ik->class_loader() == NULL) { return; } // This is a very busy routine. We don't want too much tracing // printed out. bool trace_name_printed = false; // Very noisy: only enable this call if you are trying to determine // that a specific class gets found by this routine. // RC_TRACE macro has an embedded ResourceMark // RC_TRACE_WITH_THREAD(0x00100000, THREAD, // ("adjust check: name=%s", ik->external_name())); // trace_name_printed = true; // Fix the vtable embedded in the_class and subclasses of the_class, // if one exists. We discard scratch_class and we don't keep an // instanceKlass around to hold obsolete methods so we don't have // any other instanceKlass embedded vtables to update. The vtable // holds the methodOops for virtual (but not final) methods. if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) { // ik->vtable() creates a wrapper object; rm cleans it up ResourceMark rm(THREAD); ik->vtable()->adjust_method_entries(_matching_old_methods, _matching_new_methods, _matching_methods_length, &trace_name_printed); } // If the current class has an itable and we are either redefining an // interface or if the current class is a subclass of the_class, then // we potentially have to fix the itable. If we are redefining an // interface, then we have to call adjust_method_entries() for // every instanceKlass that has an itable since there isn't a // subclass relationship between an interface and an instanceKlass. if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface() || ik->is_subclass_of(_the_class_oop))) { // ik->itable() creates a wrapper object; rm cleans it up ResourceMark rm(THREAD); ik->itable()->adjust_method_entries(_matching_old_methods, _matching_new_methods, _matching_methods_length, &trace_name_printed); } // The constant pools in other classes (other_cp) can refer to // methods in the_class. We have to update method information in // other_cp's cache. If other_cp has a previous version, then we // have to repeat the process for each previous version. The // constant pool cache holds the methodOops for non-virtual // methods and for virtual, final methods. // // Special case: if the current class is the_class, then new_cp // has already been attached to the_class and old_cp has already // been added as a previous version. The new_cp doesn't have any // cached references to old methods so it doesn't need to be // updated. We can simply start with the previous version(s) in // that case. constantPoolHandle other_cp; constantPoolCacheOop cp_cache; if (k_oop != _the_class_oop) { // this klass' constant pool cache may need adjustment other_cp = constantPoolHandle(ik->constants()); cp_cache = other_cp->cache(); if (cp_cache != NULL) { cp_cache->adjust_method_entries(_matching_old_methods, _matching_new_methods, _matching_methods_length, &trace_name_printed); } } { ResourceMark rm(THREAD); // PreviousVersionInfo objects returned via PreviousVersionWalker // contain a GrowableArray of handles. We have to clean up the // GrowableArray _after_ the PreviousVersionWalker destructor // has destroyed the handles. { // the previous versions' constant pool caches may need adjustment PreviousVersionWalker pvw(ik); for (PreviousVersionInfo * pv_info = pvw.next_previous_version(); pv_info != NULL; pv_info = pvw.next_previous_version()) { other_cp = pv_info->prev_constant_pool_handle(); cp_cache = other_cp->cache(); if (cp_cache != NULL) { cp_cache->adjust_method_entries(_matching_old_methods, _matching_new_methods, _matching_methods_length, &trace_name_printed); } } } // pvw is cleaned up } // rm is cleaned up } } void VM_RedefineClasses::update_jmethod_ids() { for (int j = 0; j < _matching_methods_length; ++j) { methodOop old_method = _matching_old_methods[j]; jmethodID jmid = old_method->find_jmethod_id_or_null(); if (jmid != NULL) { // There is a jmethodID, change it to point to the new method methodHandle new_method_h(_matching_new_methods[j]); JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h); assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j], "should be replaced"); } } } void VM_RedefineClasses::check_methods_and_mark_as_obsolete( BitMap *emcp_methods, int * emcp_method_count_p) { *emcp_method_count_p = 0; int obsolete_count = 0; int old_index = 0; for (int j = 0; j < _matching_methods_length; ++j, ++old_index) { methodOop old_method = _matching_old_methods[j]; methodOop new_method = _matching_new_methods[j]; methodOop old_array_method; // Maintain an old_index into the _old_methods array by skipping // deleted methods while ((old_array_method = (methodOop) _old_methods->obj_at(old_index)) != old_method) { ++old_index; } if (MethodComparator::methods_EMCP(old_method, new_method)) { // The EMCP definition from JSR-163 requires the bytecodes to be // the same with the exception of constant pool indices which may // differ. However, the constants referred to by those indices // must be the same. // // We use methods_EMCP() for comparison since constant pool // merging can remove duplicate constant pool entries that were // present in the old method and removed from the rewritten new // method. A faster binary comparison function would consider the // old and new methods to be different when they are actually // EMCP. // // The old and new methods are EMCP and you would think that we // could get rid of one of them here and now and save some space. // However, the concept of EMCP only considers the bytecodes and // the constant pool entries in the comparison. Other things, // e.g., the line number table (LNT) or the local variable table // (LVT) don't count in the comparison. So the new (and EMCP) // method can have a new LNT that we need so we can't just // overwrite the new method with the old method. // // When this routine is called, we have already attached the new // methods to the_class so the old methods are effectively // overwritten. However, if an old method is still executing, // then the old method cannot be collected until sometime after // the old method call has returned. So the overwriting of old // methods by new methods will save us space except for those // (hopefully few) old methods that are still executing. // // A method refers to a constMethodOop and this presents another // possible avenue to space savings. The constMethodOop in the // new method contains possibly new attributes (LNT, LVT, etc). // At first glance, it seems possible to save space by replacing // the constMethodOop in the old method with the constMethodOop // from the new method. The old and new methods would share the // same constMethodOop and we would save the space occupied by // the old constMethodOop. However, the constMethodOop contains // a back reference to the containing method. Sharing the // constMethodOop between two methods could lead to confusion in // the code that uses the back reference. This would lead to // brittle code that could be broken in non-obvious ways now or // in the future. // // Another possibility is to copy the constMethodOop from the new // method to the old method and then overwrite the new method with // the old method. Since the constMethodOop contains the bytecodes // for the method embedded in the oop, this option would change // the bytecodes out from under any threads executing the old // method and make the thread's bcp invalid. Since EMCP requires // that the bytecodes be the same modulo constant pool indices, it // is straight forward to compute the correct new bcp in the new // constMethodOop from the old bcp in the old constMethodOop. The // time consuming part would be searching all the frames in all // of the threads to find all of the calls to the old method. // // It looks like we will have to live with the limited savings // that we get from effectively overwriting the old methods // when the new methods are attached to the_class. // track which methods are EMCP for add_previous_version() call emcp_methods->set_bit(old_index); (*emcp_method_count_p)++; // An EMCP method is _not_ obsolete. An obsolete method has a // different jmethodID than the current method. An EMCP method // has the same jmethodID as the current method. Having the // same jmethodID for all EMCP versions of a method allows for // a consistent view of the EMCP methods regardless of which // EMCP method you happen to have in hand. For example, a // breakpoint set in one EMCP method will work for all EMCP // versions of the method including the current one. } else { // mark obsolete methods as such old_method->set_is_obsolete(); obsolete_count++; // obsolete methods need a unique idnum u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum(); if (num != constMethodOopDesc::UNSET_IDNUM) { // u2 old_num = old_method->method_idnum(); old_method->set_method_idnum(num); // TO DO: attach obsolete annotations to obsolete method's new idnum } // With tracing we try not to "yack" too much. The position of // this trace assumes there are fewer obsolete methods than // EMCP methods. RC_TRACE(0x00000100, ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string())); } old_method->set_is_old(); } for (int i = 0; i < _deleted_methods_length; ++i) { methodOop old_method = _deleted_methods[i]; assert(old_method->vtable_index() < 0, "cannot delete methods with vtable entries");; // Mark all deleted methods as old and obsolete old_method->set_is_old(); old_method->set_is_obsolete(); ++obsolete_count; // With tracing we try not to "yack" too much. The position of // this trace assumes there are fewer obsolete methods than // EMCP methods. RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string())); } assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(), "sanity check"); RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p, obsolete_count)); } // This internal class transfers the native function registration from old methods // to new methods. It is designed to handle both the simple case of unchanged // native methods and the complex cases of native method prefixes being added and/or // removed. // It expects only to be used during the VM_RedefineClasses op (a safepoint). // // This class is used after the new methods have been installed in "the_class". // // So, for example, the following must be handled. Where 'm' is a method and // a number followed by an underscore is a prefix. // // Old Name New Name // Simple transfer to new method m -> m // Add prefix m -> 1_m // Remove prefix 1_m -> m // Simultaneous add of prefixes m -> 3_2_1_m // Simultaneous removal of prefixes 3_2_1_m -> m // Simultaneous add and remove 1_m -> 2_m // Same, caused by prefix removal only 3_2_1_m -> 3_2_m // class TransferNativeFunctionRegistration { private: instanceKlassHandle the_class; int prefix_count; char** prefixes; // Recursively search the binary tree of possibly prefixed method names. // Iteration could be used if all agents were well behaved. Full tree walk is // more resilent to agents not cleaning up intermediate methods. // Branch at each depth in the binary tree is: // (1) without the prefix. // (2) with the prefix. // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...) methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len, Symbol* signature) { TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len); if (name_symbol != NULL) { methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature); if (method != NULL) { // Even if prefixed, intermediate methods must exist. if (method->is_native()) { // Wahoo, we found a (possibly prefixed) version of the method, return it. return method; } if (depth < prefix_count) { // Try applying further prefixes (other than this one). method = search_prefix_name_space(depth+1, name_str, name_len, signature); if (method != NULL) { return method; // found } // Try adding this prefix to the method name and see if it matches // another method name. char* prefix = prefixes[depth]; size_t prefix_len = strlen(prefix); size_t trial_len = name_len + prefix_len; char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1); strcpy(trial_name_str, prefix); strcat(trial_name_str, name_str); method = search_prefix_name_space(depth+1, trial_name_str, trial_len, signature); if (method != NULL) { // If found along this branch, it was prefixed, mark as such method->set_is_prefixed_native(); return method; // found } } } } return NULL; // This whole branch bore nothing } // Return the method name with old prefixes stripped away. char* method_name_without_prefixes(methodOop method) { Symbol* name = method->name(); char* name_str = name->as_utf8(); // Old prefixing may be defunct, strip prefixes, if any. for (int i = prefix_count-1; i >= 0; i--) { char* prefix = prefixes[i]; size_t prefix_len = strlen(prefix); if (strncmp(prefix, name_str, prefix_len) == 0) { name_str += prefix_len; } } return name_str; } // Strip any prefixes off the old native method, then try to find a // (possibly prefixed) new native that matches it. methodOop strip_and_search_for_new_native(methodOop method) { ResourceMark rm; char* name_str = method_name_without_prefixes(method); return search_prefix_name_space(0, name_str, strlen(name_str), method->signature()); } public: // Construct a native method transfer processor for this class. TransferNativeFunctionRegistration(instanceKlassHandle _the_class) { assert(SafepointSynchronize::is_at_safepoint(), "sanity check"); the_class = _the_class; prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count); } // Attempt to transfer any of the old or deleted methods that are native void transfer_registrations(methodOop* old_methods, int methods_length) { for (int j = 0; j < methods_length; j++) { methodOop old_method = old_methods[j]; if (old_method->is_native() && old_method->has_native_function()) { methodOop new_method = strip_and_search_for_new_native(old_method); if (new_method != NULL) { // Actually set the native function in the new method. // Redefine does not send events (except CFLH), certainly not this // behind the scenes re-registration. new_method->set_native_function(old_method->native_function(), !methodOopDesc::native_bind_event_is_interesting); } } } } }; // Don't lose the association between a native method and its JNI function. void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) { TransferNativeFunctionRegistration transfer(the_class); transfer.transfer_registrations(_deleted_methods, _deleted_methods_length); transfer.transfer_registrations(_matching_old_methods, _matching_methods_length); } // Deoptimize all compiled code that depends on this class. // // If the can_redefine_classes capability is obtained in the onload // phase then the compiler has recorded all dependencies from startup. // In that case we need only deoptimize and throw away all compiled code // that depends on the class. // // If can_redefine_classes is obtained sometime after the onload // phase then the dependency information may be incomplete. In that case // the first call to RedefineClasses causes all compiled code to be // thrown away. As can_redefine_classes has been obtained then // all future compilations will record dependencies so second and // subsequent calls to RedefineClasses need only throw away code // that depends on the class. // void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) { assert_locked_or_safepoint(Compile_lock); // All dependencies have been recorded from startup or this is a second or // subsequent use of RedefineClasses if (JvmtiExport::all_dependencies_are_recorded()) { Universe::flush_evol_dependents_on(k_h); } else { CodeCache::mark_all_nmethods_for_deoptimization(); ResourceMark rm(THREAD); DeoptimizationMarker dm; // Deoptimize all activations depending on marked nmethods Deoptimization::deoptimize_dependents(); // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies) CodeCache::make_marked_nmethods_not_entrant(); // From now on we know that the dependency information is complete JvmtiExport::set_all_dependencies_are_recorded(true); } } void VM_RedefineClasses::compute_added_deleted_matching_methods() { methodOop old_method; methodOop new_method; _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); _added_methods = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length()); _deleted_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); _matching_methods_length = 0; _deleted_methods_length = 0; _added_methods_length = 0; int nj = 0; int oj = 0; while (true) { if (oj >= _old_methods->length()) { if (nj >= _new_methods->length()) { break; // we've looked at everything, done } // New method at the end new_method = (methodOop) _new_methods->obj_at(nj); _added_methods[_added_methods_length++] = new_method; ++nj; } else if (nj >= _new_methods->length()) { // Old method, at the end, is deleted old_method = (methodOop) _old_methods->obj_at(oj); _deleted_methods[_deleted_methods_length++] = old_method; ++oj; } else { old_method = (methodOop) _old_methods->obj_at(oj); new_method = (methodOop) _new_methods->obj_at(nj); if (old_method->name() == new_method->name()) { if (old_method->signature() == new_method->signature()) { _matching_old_methods[_matching_methods_length ] = old_method; _matching_new_methods[_matching_methods_length++] = new_method; ++nj; ++oj; } else { // added overloaded have already been moved to the end, // so this is a deleted overloaded method _deleted_methods[_deleted_methods_length++] = old_method; ++oj; } } else { // names don't match if (old_method->name()->fast_compare(new_method->name()) > 0) { // new method _added_methods[_added_methods_length++] = new_method; ++nj; } else { // deleted method _deleted_methods[_deleted_methods_length++] = old_method; ++oj; } } } } assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity"); assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity"); } // Install the redefinition of a class: // - house keeping (flushing breakpoints and caches, deoptimizing // dependent compiled code) // - replacing parts in the_class with parts from scratch_class // - adding a weak reference to track the obsolete but interesting // parts of the_class // - adjusting constant pool caches and vtables in other classes // that refer to methods in the_class. These adjustments use the // SystemDictionary::classes_do() facility which only allows // a helper method to be specified. The interesting parameters // that we would like to pass to the helper method are saved in // static global fields in the VM operation. void VM_RedefineClasses::redefine_single_class(jclass the_jclass, instanceKlassHandle scratch_class, TRAPS) { RC_TIMER_START(_timer_rsc_phase1); oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass); klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror); instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); #ifndef JVMTI_KERNEL // Remove all breakpoints in methods of this class JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints(); jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop); #endif // !JVMTI_KERNEL if (the_class_oop == Universe::reflect_invoke_cache()->klass()) { // We are redefining java.lang.reflect.Method. Method.invoke() is // cached and users of the cache care about each active version of // the method so we have to track this previous version. // Do this before methods get switched Universe::reflect_invoke_cache()->add_previous_version( the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum())); } // Deoptimize all compiled code that depends on this class flush_dependent_code(the_class, THREAD); _old_methods = the_class->methods(); _new_methods = scratch_class->methods(); _the_class_oop = the_class_oop; compute_added_deleted_matching_methods(); update_jmethod_ids(); // Attach new constant pool to the original klass. The original // klass still refers to the old constant pool (for now). scratch_class->constants()->set_pool_holder(the_class()); #if 0 // In theory, with constant pool merging in place we should be able // to save space by using the new, merged constant pool in place of // the old constant pool(s). By "pool(s)" I mean the constant pool in // the klass version we are replacing now and any constant pool(s) in // previous versions of klass. Nice theory, doesn't work in practice. // When this code is enabled, even simple programs throw NullPointer // exceptions. I'm guessing that this is caused by some constant pool // cache difference between the new, merged constant pool and the // constant pool that was just being used by the klass. I'm keeping // this code around to archive the idea, but the code has to remain // disabled for now. // Attach each old method to the new constant pool. This can be // done here since we are past the bytecode verification and // constant pool optimization phases. for (int i = _old_methods->length() - 1; i >= 0; i--) { methodOop method = (methodOop)_old_methods->obj_at(i); method->set_constants(scratch_class->constants()); } { // walk all previous versions of the klass instanceKlass *ik = (instanceKlass *)the_class()->klass_part(); PreviousVersionWalker pvw(ik); instanceKlassHandle ikh; do { ikh = pvw.next_previous_version(); if (!ikh.is_null()) { ik = ikh(); // attach previous version of klass to the new constant pool ik->set_constants(scratch_class->constants()); // Attach each method in the previous version of klass to the // new constant pool objArrayOop prev_methods = ik->methods(); for (int i = prev_methods->length() - 1; i >= 0; i--) { methodOop method = (methodOop)prev_methods->obj_at(i); method->set_constants(scratch_class->constants()); } } } while (!ikh.is_null()); } #endif // Replace methods and constantpool the_class->set_methods(_new_methods); scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods, // and to be able to undo operation easily. constantPoolOop old_constants = the_class->constants(); the_class->set_constants(scratch_class->constants()); scratch_class->set_constants(old_constants); // See the previous comment. #if 0 // We are swapping the guts of "the new class" with the guts of "the // class". Since the old constant pool has just been attached to "the // new class", it seems logical to set the pool holder in the old // constant pool also. However, doing this will change the observable // class hierarchy for any old methods that are still executing. A // method can query the identity of its "holder" and this query uses // the method's constant pool link to find the holder. The change in // holding class from "the class" to "the new class" can confuse // things. // // Setting the old constant pool's holder will also cause // verification done during vtable initialization below to fail. // During vtable initialization, the vtable's class is verified to be // a subtype of the method's holder. The vtable's class is "the // class" and the method's holder is gotten from the constant pool // link in the method itself. For "the class"'s directly implemented // methods, the method holder is "the class" itself (as gotten from // the new constant pool). The check works fine in this case. The // check also works fine for methods inherited from super classes. // // Miranda methods are a little more complicated. A miranda method is // provided by an interface when the class implementing the interface // does not provide its own method. These interfaces are implemented // internally as an instanceKlass. These special instanceKlasses // share the constant pool of the class that "implements" the // interface. By sharing the constant pool, the method holder of a // miranda method is the class that "implements" the interface. In a // non-redefine situation, the subtype check works fine. However, if // the old constant pool's pool holder is modified, then the check // fails because there is no class hierarchy relationship between the // vtable's class and "the new class". old_constants->set_pool_holder(scratch_class()); #endif // track which methods are EMCP for add_previous_version() call below BitMap emcp_methods(_old_methods->length()); int emcp_method_count = 0; emcp_methods.clear(); // clears 0..(length() - 1) check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count); transfer_old_native_function_registrations(the_class); // The class file bytes from before any retransformable agents mucked // with them was cached on the scratch class, move to the_class. // Note: we still want to do this if nothing needed caching since it // should get cleared in the_class too. the_class->set_cached_class_file(scratch_class->get_cached_class_file_bytes(), scratch_class->get_cached_class_file_len()); // Replace inner_classes typeArrayOop old_inner_classes = the_class->inner_classes(); the_class->set_inner_classes(scratch_class->inner_classes()); scratch_class->set_inner_classes(old_inner_classes); // Initialize the vtable and interface table after // methods have been rewritten { ResourceMark rm(THREAD); // no exception should happen here since we explicitly // do not check loader constraints. // compare_and_normalize_class_versions has already checked: // - classloaders unchanged, signatures unchanged // - all instanceKlasses for redefined classes reused & contents updated the_class->vtable()->initialize_vtable(false, THREAD); the_class->itable()->initialize_itable(false, THREAD); assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception"); } // Leave arrays of jmethodIDs and itable index cache unchanged // Copy the "source file name" attribute from new class version the_class->set_source_file_name(scratch_class->source_file_name()); // Copy the "source debug extension" attribute from new class version the_class->set_source_debug_extension( scratch_class->source_debug_extension()); // Use of javac -g could be different in the old and the new if (scratch_class->access_flags().has_localvariable_table() != the_class->access_flags().has_localvariable_table()) { AccessFlags flags = the_class->access_flags(); if (scratch_class->access_flags().has_localvariable_table()) { flags.set_has_localvariable_table(); } else { flags.clear_has_localvariable_table(); } the_class->set_access_flags(flags); } // Replace class annotation fields values typeArrayOop old_class_annotations = the_class->class_annotations(); the_class->set_class_annotations(scratch_class->class_annotations()); scratch_class->set_class_annotations(old_class_annotations); // Replace fields annotation fields values objArrayOop old_fields_annotations = the_class->fields_annotations(); the_class->set_fields_annotations(scratch_class->fields_annotations()); scratch_class->set_fields_annotations(old_fields_annotations); // Replace methods annotation fields values objArrayOop old_methods_annotations = the_class->methods_annotations(); the_class->set_methods_annotations(scratch_class->methods_annotations()); scratch_class->set_methods_annotations(old_methods_annotations); // Replace methods parameter annotation fields values objArrayOop old_methods_parameter_annotations = the_class->methods_parameter_annotations(); the_class->set_methods_parameter_annotations( scratch_class->methods_parameter_annotations()); scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations); // Replace methods default annotation fields values objArrayOop old_methods_default_annotations = the_class->methods_default_annotations(); the_class->set_methods_default_annotations( scratch_class->methods_default_annotations()); scratch_class->set_methods_default_annotations(old_methods_default_annotations); // Replace minor version number of class file u2 old_minor_version = the_class->minor_version(); the_class->set_minor_version(scratch_class->minor_version()); scratch_class->set_minor_version(old_minor_version); // Replace major version number of class file u2 old_major_version = the_class->major_version(); the_class->set_major_version(scratch_class->major_version()); scratch_class->set_major_version(old_major_version); // Replace CP indexes for class and name+type of enclosing method u2 old_class_idx = the_class->enclosing_method_class_index(); u2 old_method_idx = the_class->enclosing_method_method_index(); the_class->set_enclosing_method_indices( scratch_class->enclosing_method_class_index(), scratch_class->enclosing_method_method_index()); scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx); // keep track of previous versions of this class the_class->add_previous_version(scratch_class, &emcp_methods, emcp_method_count); RC_TIMER_STOP(_timer_rsc_phase1); RC_TIMER_START(_timer_rsc_phase2); // Adjust constantpool caches and vtables for all classes // that reference methods of the evolved class. SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD); if (the_class->oop_map_cache() != NULL) { // Flush references to any obsolete methods from the oop map cache // so that obsolete methods are not pinned. the_class->oop_map_cache()->flush_obsolete_entries(); } // increment the classRedefinedCount field in the_class and in any // direct and indirect subclasses of the_class increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD); // RC_TRACE macro has an embedded ResourceMark RC_TRACE_WITH_THREAD(0x00000001, THREAD, ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), java_lang_Class::classRedefinedCount(the_class_mirror), os::available_memory() >> 10)); RC_TIMER_STOP(_timer_rsc_phase2); } // end redefine_single_class() // Increment the classRedefinedCount field in the specific instanceKlass // and in all direct and indirect subclasses. void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) { oop class_mirror = ik->java_mirror(); klassOop class_oop = java_lang_Class::as_klassOop(class_mirror); int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1; java_lang_Class::set_classRedefinedCount(class_mirror, new_count); if (class_oop != _the_class_oop) { // _the_class_oop count is printed at end of redefine_single_class() RC_TRACE_WITH_THREAD(0x00000008, THREAD, ("updated count in subclass=%s to %d", ik->external_name(), new_count)); } for (Klass *subk = ik->subklass(); subk != NULL; subk = subk->next_sibling()) { klassOop sub = subk->as_klassOop(); instanceKlass *subik = (instanceKlass *)sub->klass_part(); // recursively do subclasses of the current subclass increment_class_counter(subik, THREAD); } } #ifndef PRODUCT void VM_RedefineClasses::check_class(klassOop k_oop, oop initiating_loader, TRAPS) { Klass *k = k_oop->klass_part(); if (k->oop_is_instance()) { HandleMark hm(THREAD); instanceKlass *ik = (instanceKlass *) k; if (ik->vtable_length() > 0) { ResourceMark rm(THREAD); if (!ik->vtable()->check_no_old_entries()) { tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name()); ik->vtable()->dump_vtable(); dump_methods(); assert(false, "OLD method found"); } } } } void VM_RedefineClasses::dump_methods() { int j; tty->print_cr("_old_methods --"); for (j = 0; j < _old_methods->length(); ++j) { methodOop m = (methodOop) _old_methods->obj_at(j); tty->print("%4d (%5d) ", j, m->vtable_index()); m->access_flags().print_on(tty); tty->print(" -- "); m->print_name(tty); tty->cr(); } tty->print_cr("_new_methods --"); for (j = 0; j < _new_methods->length(); ++j) { methodOop m = (methodOop) _new_methods->obj_at(j); tty->print("%4d (%5d) ", j, m->vtable_index()); m->access_flags().print_on(tty); tty->print(" -- "); m->print_name(tty); tty->cr(); } tty->print_cr("_matching_(old/new)_methods --"); for (j = 0; j < _matching_methods_length; ++j) { methodOop m = _matching_old_methods[j]; tty->print("%4d (%5d) ", j, m->vtable_index()); m->access_flags().print_on(tty); tty->print(" -- "); m->print_name(tty); tty->cr(); m = _matching_new_methods[j]; tty->print(" (%5d) ", m->vtable_index()); m->access_flags().print_on(tty); tty->cr(); } tty->print_cr("_deleted_methods --"); for (j = 0; j < _deleted_methods_length; ++j) { methodOop m = _deleted_methods[j]; tty->print("%4d (%5d) ", j, m->vtable_index()); m->access_flags().print_on(tty); tty->print(" -- "); m->print_name(tty); tty->cr(); } tty->print_cr("_added_methods --"); for (j = 0; j < _added_methods_length; ++j) { methodOop m = _added_methods[j]; tty->print("%4d (%5d) ", j, m->vtable_index()); m->access_flags().print_on(tty); tty->print(" -- "); m->print_name(tty); tty->cr(); } } #endif