1 /*
2 * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/archiveHeapLoader.hpp"
27 #include "cds/classPreloader.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/classLoaderData.hpp"
30 #include "classfile/dictionary.hpp"
31 #include "classfile/javaClasses.hpp"
32 #include "classfile/systemDictionary.hpp"
33 #include "classfile/vmClasses.hpp"
34 #include "classfile/vmSymbols.hpp"
35 #include "gc/shared/collectedHeap.hpp"
36 #include "memory/metaspaceClosure.hpp"
37 #include "memory/universe.hpp"
38 #include "oops/instanceKlass.hpp"
39 #include "oops/instanceRefKlass.hpp"
40 #include "oops/instanceStackChunkKlass.hpp"
41 #include "prims/jvmtiExport.hpp"
42 #include "runtime/globals.hpp"
43
44 InstanceKlass* vmClasses::_klasses[static_cast<int>(vmClassID::LIMIT)]
45 = { nullptr /*, nullptr...*/ };
46 InstanceKlass* vmClasses::_box_klasses[T_VOID+1] = { nullptr /*, nullptr...*/ };
47
48
49 // CDS: scan and relocate all classes referenced by _klasses[].
50 void vmClasses::metaspace_pointers_do(MetaspaceClosure* it) {
51 for (auto id : EnumRange<vmClassID>{}) {
52 it->push(klass_addr_at(id));
53 }
54 }
55
56 bool vmClasses::is_loaded(InstanceKlass* klass) {
57 return klass != nullptr && klass->is_loaded();
58 }
59
60 // Compact table of the vmSymbolIDs of all the VM classes (stored as short to save space)
61 static const short vm_class_name_ids[] = {
62 #define VM_CLASS_NAME(name, symbol) ((short)VM_SYMBOL_ENUM_NAME(symbol)),
63 VM_CLASSES_DO(VM_CLASS_NAME)
64 #undef VM_CLASS_NAME
65 0
66 };
67
68
69 #ifdef ASSERT
70 bool vmClasses::contain(Symbol* class_name) {
71 int sid;
72 for (int i = 0; (sid = vm_class_name_ids[i]) != 0; i++) {
73 Symbol* symbol = vmSymbols::symbol_at(vmSymbols::as_SID(sid));
74 if (class_name == symbol) {
75 return true;
76 }
77 }
78 return false;
79 }
80
81 bool vmClasses::contain(Klass* k) {
82 return contain(k->name());
83 }
84 #endif
85
86 bool vmClasses::resolve(vmClassID id, TRAPS) {
87 InstanceKlass** klassp = &_klasses[as_int(id)];
88
89 #if INCLUDE_CDS
90 if (UseSharedSpaces && !JvmtiExport::should_post_class_prepare()) {
91 InstanceKlass* k = *klassp;
92 assert(k->is_shared_boot_class(), "must be");
93
94 ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
95 resolve_shared_class(k, loader_data, Handle(), CHECK_false);
96 return true;
97 }
98 #endif // INCLUDE_CDS
99
100 if (!is_loaded(*klassp)) {
101 int sid = vm_class_name_ids[as_int(id)];
102 Symbol* symbol = vmSymbols::symbol_at(vmSymbols::as_SID(sid));
103 Klass* k = SystemDictionary::resolve_or_fail(symbol, true, CHECK_false);
104 (*klassp) = InstanceKlass::cast(k);
105 }
106 return ((*klassp) != nullptr);
107 }
108
109 void vmClasses::resolve_until(vmClassID limit_id, vmClassID &start_id, TRAPS) {
110 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
111 for (auto id : EnumRange<vmClassID>{start_id, limit_id}) { // (inclusive start, exclusive end)
112 resolve(id, CHECK);
113 }
114
115 // move the starting value forward to the limit:
116 start_id = limit_id;
117 }
118
119 void vmClasses::resolve_all(TRAPS) {
120 assert(!Object_klass_loaded(), "well-known classes should only be initialized once");
121
122 // Create the ModuleEntry for java.base. This call needs to be done here,
123 // after vmSymbols::initialize() is called but before any classes are pre-loaded.
124 ClassLoader::classLoader_init2(THREAD);
125
126 // Preload commonly used klasses
127 vmClassID scan = vmClassID::FIRST;
128 // first do Object, then String, Class
129 resolve_through(VM_CLASS_ID(Object_klass), scan, CHECK);
130 CollectedHeap::set_filler_object_klass(vmClasses::Object_klass());
131 #if INCLUDE_CDS
132 if (UseSharedSpaces) {
133 // It's unsafe to access the archived heap regions before they
134 // are fixed up, so we must do the fixup as early as possible
135 // before the archived java objects are accessed by functions
136 // such as java_lang_Class::restore_archived_mirror and
137 // ConstantPool::restore_unshareable_info (restores the archived
138 // resolved_references array object).
139 //
140 // ArchiveHeapLoader::fixup_regions fills the empty
141 // spaces in the archived heap regions and may use
142 // vmClasses::Object_klass(), so we can do this only after
143 // Object_klass is resolved. See the above resolve_through()
144 // call. No mirror objects are accessed/restored in the above call.
145 // Mirrors are restored after java.lang.Class is loaded.
146 ArchiveHeapLoader::fixup_region();
147
148 // Initialize the constant pool for the Object_class
149 assert(Object_klass()->is_shared(), "must be");
150 Object_klass()->constants()->restore_unshareable_info(CHECK);
151 resolve_through(VM_CLASS_ID(Class_klass), scan, CHECK);
152 } else
153 #endif
154 {
155 resolve_through(VM_CLASS_ID(Class_klass), scan, CHECK);
156 }
157
158 assert(vmClasses::Object_klass() != nullptr, "well-known classes should now be initialized");
159
160 java_lang_Object::register_natives(CHECK);
161
162 // Calculate offsets for String and Class classes since they are loaded and
163 // can be used after this point. These are no-op when CDS is enabled.
164 java_lang_String::compute_offsets();
165 java_lang_Class::compute_offsets();
166
167 // Fixup mirrors for classes loaded before java.lang.Class.
168 Universe::initialize_basic_type_mirrors(CHECK);
169 Universe::fixup_mirrors(CHECK);
170
171 if (UseSharedSpaces) {
172 // These should already have been initialized during CDS dump.
173 assert(vmClasses::Reference_klass()->reference_type() == REF_NONE, "sanity");
174 assert(vmClasses::SoftReference_klass()->reference_type() == REF_SOFT, "sanity");
175 assert(vmClasses::WeakReference_klass()->reference_type() == REF_WEAK, "sanity");
176 assert(vmClasses::FinalReference_klass()->reference_type() == REF_FINAL, "sanity");
177 assert(vmClasses::PhantomReference_klass()->reference_type() == REF_PHANTOM, "sanity");
178 } else {
179 // If CDS is not enabled, the references classes must be initialized in
180 // this order before the rest of the vmClasses can be resolved.
181 resolve_through(VM_CLASS_ID(Reference_klass), scan, CHECK);
182
183 // The offsets for jlr.Reference must be computed before
184 // InstanceRefKlass::update_nonstatic_oop_maps is called. That function uses
185 // the offsets to remove the referent and discovered fields from the oop maps,
186 // as they are treated in a special way by the GC. Removing these oops from the
187 // oop maps must be done before the usual subclasses of jlr.Reference are loaded.
188 java_lang_ref_Reference::compute_offsets();
189
190 // Preload ref klasses and set reference types
191 InstanceRefKlass::update_nonstatic_oop_maps(vmClasses::Reference_klass());
192
193 resolve_through(VM_CLASS_ID(PhantomReference_klass), scan, CHECK);
194 }
195
196 resolve_until(vmClassID::LIMIT, scan, CHECK);
197
198 CollectedHeap::set_filler_object_klass(vmClasses::FillerObject_klass());
199
200 _box_klasses[T_BOOLEAN] = vmClasses::Boolean_klass();
201 _box_klasses[T_CHAR] = vmClasses::Character_klass();
202 _box_klasses[T_FLOAT] = vmClasses::Float_klass();
203 _box_klasses[T_DOUBLE] = vmClasses::Double_klass();
204 _box_klasses[T_BYTE] = vmClasses::Byte_klass();
205 _box_klasses[T_SHORT] = vmClasses::Short_klass();
206 _box_klasses[T_INT] = vmClasses::Integer_klass();
207 _box_klasses[T_LONG] = vmClasses::Long_klass();
208 //_box_klasses[T_OBJECT] = vmClasses::object_klass();
209 //_box_klasses[T_ARRAY] = vmClasses::object_klass();
210
211 #ifdef ASSERT
212 if (UseSharedSpaces) {
213 JVMTI_ONLY(assert(JvmtiExport::is_early_phase(),
214 "All well known classes must be resolved in JVMTI early phase"));
215 for (auto id : EnumRange<vmClassID>{}) {
216 InstanceKlass* k = _klasses[as_int(id)];
217 assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
218 }
219 }
220 #endif
221
222 InstanceStackChunkKlass::init_offset_of_stack();
223 ClassPreloader::runtime_preload(THREAD, Handle()); // load only java.base classes
224 }
225
226 #if INCLUDE_CDS
227
228 void vmClasses::resolve_shared_class(InstanceKlass* klass, ClassLoaderData* loader_data, Handle domain, TRAPS) {
229 assert(!Universe::is_fully_initialized(), "We can make short cuts only during VM initialization");
230 assert(klass->is_shared(), "Must be shared class");
231 if (klass->class_loader_data() != nullptr) {
232 return;
233 }
234
235 // add super and interfaces first
236 Klass* super = klass->super();
237 if (super != nullptr && super->class_loader_data() == nullptr) {
238 assert(super->is_instance_klass(), "Super should be instance klass");
239 resolve_shared_class(InstanceKlass::cast(super), loader_data, domain, CHECK);
240 }
241
242 Array<InstanceKlass*>* ifs = klass->local_interfaces();
243 for (int i = 0; i < ifs->length(); i++) {
244 InstanceKlass* ik = ifs->at(i);
245 if (ik->class_loader_data() == nullptr) {
246 resolve_shared_class(ik, loader_data, domain, CHECK);
247 }
248 }
249
250 klass->restore_unshareable_info(loader_data, domain, nullptr, THREAD);
251 SystemDictionary::load_shared_class_misc(klass, loader_data);
252 Dictionary* dictionary = loader_data->dictionary();
253 dictionary->add_klass(THREAD, klass->name(), klass);
254 klass->add_to_hierarchy(THREAD);
255 assert(klass->is_loaded(), "Must be in at least loaded state");
256 }
257
258 #endif // INCLUDE_CDS
259
260 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
261 // If so, returns the basic type it holds. If not, returns T_OBJECT.
262 BasicType vmClasses::box_klass_type(Klass* k) {
263 assert(k != nullptr, "");
264 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
265 if (_box_klasses[i] == k)
266 return (BasicType)i;
267 }
268 return T_OBJECT;
269 }