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/*
* Copyright (c) 2022, 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 "cds/archiveBuilder.hpp"
#include "cds/cdsHeapVerifier.hpp"
#include "classfile/classLoaderDataGraph.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/resourceArea.hpp"
#include "oops/fieldStreams.inline.hpp"
#include "oops/klass.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/fieldDescriptor.inline.hpp"
#if INCLUDE_CDS_JAVA_HEAP
// CDSHeapVerifier is used to check for problems where an archived object references a
// static field that may be reinitialized at runtime. In the following example,
// Foo.get.test()
// correctly returns true when CDS disabled, but incorrectly returns false when CDS is enabled.
//
// class Foo {
// final Foo archivedFoo; // this field is archived by CDS
// Bar bar;
// static {
// CDS.initializeFromArchive(Foo.class);
// if (archivedFoo == null) {
// archivedFoo = new Foo();
// archivedFoo.bar = Bar.bar;
// }
// }
// static Foo get() { return archivedFoo; }
// boolean test() {
// return bar == Bar.bar;
// }
// }
//
// class Bar {
// // this field is initialized in both CDS dump time and runtime.
// static final Bar bar = new Bar();
// }
//
// The check itself is simple:
// [1] CDSHeapVerifier::do_klass() collects all static fields
// [2] CDSHeapVerifier::do_entry() checks all the archived objects. None of them
// should be in [1]
//
// However, it's legal for *some* static fields to be references. This leads to the
// table of ADD_EXCL below.
//
// [A] In most of the cases, the module bootstrap code will update the static field
// to point to part of the archived module graph. E.g.,
// - java/lang/System::bootLayer
// - jdk/internal/loader/ClassLoaders::BOOT_LOADER
// [B] A final static String that's explicitly initialized inside <clinit>, but
// its value is deterministic and is always the same string literal.
// [C] A non-final static string that is assigned a string literal during class
// initialization; this string is never changed during -Xshare:dump.
// [D] Simple caches whose value doesn't matter.
// [E] Other cases (see comments in-line below).
CDSHeapVerifier::CDSHeapVerifier() : _archived_objs(0), _problems(0)
{
# define ADD_EXCL(...) { static const char* e[] = {__VA_ARGS__, NULL}; add_exclusion(e); }
// Unfortunately this needs to be manually maintained. If
// test/hotspot/jtreg/runtime/cds/appcds/cacheObject/ArchivedEnumTest.java fails,
// you might need to fix the core library code, or fix the ADD_EXCL entries below.
//
// class field type
ADD_EXCL("java/lang/ClassLoader", "scl"); // A
ADD_EXCL("java/lang/invoke/InvokerBytecodeGenerator", "DONTINLINE_SIG", // B
"FORCEINLINE_SIG", // B
"HIDDEN_SIG", // B
"INJECTEDPROFILE_SIG", // B
"LF_COMPILED_SIG"); // B
ADD_EXCL("java/lang/Module", "ALL_UNNAMED_MODULE", // A
"ALL_UNNAMED_MODULE_SET", // A
"EVERYONE_MODULE", // A
"EVERYONE_SET"); // A
// This is the same as java/util/ImmutableCollections::EMPTY_SET, which is archived
ADD_EXCL("java/lang/reflect/AccessFlag$Location", "EMPTY_SET"); // E
ADD_EXCL("java/lang/System", "bootLayer"); // A
ADD_EXCL("java/lang/VersionProps", "VENDOR_URL_BUG", // C
"VENDOR_URL_VM_BUG", // C
"VENDOR_VERSION"); // C
ADD_EXCL("java/net/URL$DefaultFactory", "PREFIX"); // B FIXME: JDK-8276561
// A dummy object used by HashSet. The value doesn't matter and it's never
// tested for equality.
ADD_EXCL("java/util/HashSet", "PRESENT"); // E
ADD_EXCL("jdk/internal/loader/BuiltinClassLoader", "packageToModule"); // A
ADD_EXCL("jdk/internal/loader/ClassLoaders", "BOOT_LOADER", // A
"APP_LOADER", // A
"PLATFORM_LOADER"); // A
ADD_EXCL("jdk/internal/loader/URLClassPath", "JAVA_VERSION"); // B
ADD_EXCL("jdk/internal/module/Builder", "cachedVersion"); // D
ADD_EXCL("jdk/internal/module/ModuleLoaderMap$Mapper", "APP_CLASSLOADER", // A
"APP_LOADER_INDEX", // A
"PLATFORM_CLASSLOADER", // A
"PLATFORM_LOADER_INDEX"); // A
ADD_EXCL("jdk/internal/module/ServicesCatalog", "CLV"); // A
// This just points to an empty Map
ADD_EXCL("jdk/internal/reflect/Reflection", "methodFilterMap"); // E
ADD_EXCL("jdk/internal/util/StaticProperty", "FILE_ENCODING", // C
"JAVA_LOCALE_USE_OLD_ISO_CODES"); // C
// Integer for 0 and 1 are in java/lang/Integer$IntegerCache and are archived
ADD_EXCL("sun/invoke/util/ValueConversions", "ONE_INT", // E
"ZERO_INT"); // E
ADD_EXCL("sun/security/util/SecurityConstants", "PROVIDER_VER"); // C
# undef ADD_EXCL
ClassLoaderDataGraph::classes_do(this);
}
CDSHeapVerifier::~CDSHeapVerifier() {
if (_problems > 0) {
log_warning(cds, heap)("Scanned %d objects. Found %d case(s) where "
"an object points to a static field that may be "
"reinitialized at runtime.", _archived_objs, _problems);
}
}
class CDSHeapVerifier::CheckStaticFields : public FieldClosure {
CDSHeapVerifier* _verifier;
InstanceKlass* _ik;
const char** _exclusions;
public:
CheckStaticFields(CDSHeapVerifier* verifier, InstanceKlass* ik)
: _verifier(verifier), _ik(ik) {
_exclusions = _verifier->find_exclusion(_ik);
}
void do_field(fieldDescriptor* fd) {
if (fd->field_type() != T_OBJECT) {
return;
}
oop static_obj_field = _ik->java_mirror()->obj_field(fd->offset());
if (static_obj_field != NULL) {
Klass* klass = static_obj_field->klass();
if (_exclusions != NULL) {
for (const char** p = _exclusions; *p != NULL; p++) {
if (fd->name()->equals(*p)) {
return;
}
}
}
if (fd->is_final() && java_lang_String::is_instance(static_obj_field) && fd->has_initial_value()) {
// This field looks like like this in the Java source:
// static final SOME_STRING = "a string literal";
// This string literal has been stored in the shared string table, so it's OK
// for the archived objects to refer to it.
return;
}
if (fd->is_final() && java_lang_Class::is_instance(static_obj_field)) {
// This field points to an archived mirror.
return;
}
if (klass->has_archived_enum_objs()) {
// This klass is a subclass of java.lang.Enum. If any instance of this klass
// has been archived, we will archive all static fields of this klass.
// See HeapShared::initialize_enum_klass().
return;
}
// This field *may* be initialized to a different value at runtime. Remember it
// and check later if it appears in the archived object graph.
_verifier->add_static_obj_field(_ik, static_obj_field, fd->name());
}
}
};
// Remember all the static object fields of every class that are currently
// loaded.
void CDSHeapVerifier::do_klass(Klass* k) {
if (k->is_instance_klass()) {
InstanceKlass* ik = InstanceKlass::cast(k);
if (HeapShared::is_subgraph_root_class(ik)) {
// ik is inside one of the ArchivableStaticFieldInfo tables
// in heapShared.cpp. We assume such classes are programmed to
// update their static fields correctly at runtime.
return;
}
CheckStaticFields csf(this, ik);
ik->do_local_static_fields(&csf);
}
}
void CDSHeapVerifier::add_static_obj_field(InstanceKlass* ik, oop field, Symbol* name) {
StaticFieldInfo info = {ik, name};
_table.put(field, info);
}
inline bool CDSHeapVerifier::do_entry(oop& orig_obj, HeapShared::CachedOopInfo& value) {
_archived_objs++;
StaticFieldInfo* info = _table.get(orig_obj);
if (info != NULL) {
ResourceMark rm;
LogStream ls(Log(cds, heap)::warning());
ls.print_cr("Archive heap points to a static field that may be reinitialized at runtime:");
ls.print_cr("Field: %s::%s", info->_holder->name()->as_C_string(), info->_name->as_C_string());
ls.print("Value: ");
orig_obj->print_on(&ls);
ls.print_cr("--- trace begin ---");
trace_to_root(orig_obj, NULL, &value);
ls.print_cr("--- trace end ---");
ls.cr();
_problems ++;
}
return true; /* keep on iterating */
}
class CDSHeapVerifier::TraceFields : public FieldClosure {
oop _orig_obj;
oop _orig_field;
LogStream* _ls;
public:
TraceFields(oop orig_obj, oop orig_field, LogStream* ls)
: _orig_obj(orig_obj), _orig_field(orig_field), _ls(ls) {}
void do_field(fieldDescriptor* fd) {
if (fd->field_type() == T_OBJECT || fd->field_type() == T_ARRAY) {
oop obj_field = _orig_obj->obj_field(fd->offset());
if (obj_field == _orig_field) {
_ls->print("::%s (offset = %d)", fd->name()->as_C_string(), fd->offset());
}
}
}
};
// Hint: to exercise this function, uncomment out one of the ADD_EXCL lines above.
int CDSHeapVerifier::trace_to_root(oop orig_obj, oop orig_field, HeapShared::CachedOopInfo* p) {
int level = 0;
LogStream ls(Log(cds, heap)::warning());
if (p->_referrer != NULL) {
HeapShared::CachedOopInfo* ref = HeapShared::archived_object_cache()->get(p->_referrer);
assert(ref != NULL, "sanity");
level = trace_to_root(p->_referrer, orig_obj, ref) + 1;
} else if (java_lang_String::is_instance(orig_obj)) {
ls.print_cr("[%2d] (shared string table)", level++);
}
Klass* k = orig_obj->klass();
ResourceMark rm;
ls.print("[%2d] ", level);
orig_obj->print_address_on(&ls);
ls.print(" %s", k->internal_name());
if (orig_field != NULL) {
if (k->is_instance_klass()) {
TraceFields clo(orig_obj, orig_field, &ls);;
InstanceKlass::cast(k)->do_nonstatic_fields(&clo);
} else {
assert(orig_obj->is_objArray(), "must be");
objArrayOop array = (objArrayOop)orig_obj;
for (int i = 0; i < array->length(); i++) {
if (array->obj_at(i) == orig_field) {
ls.print(" @[%d]", i);
break;
}
}
}
}
ls.cr();
return level;
}
#ifdef ASSERT
void CDSHeapVerifier::verify() {
CDSHeapVerifier verf;
HeapShared::archived_object_cache()->iterate(&verf);
}
#endif
#endif // INCLUDE_CDS_JAVA_HEAP
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