1 /*
2 * Copyright (c) 2016, 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 "classfile/classLoaderData.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "logging/log.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/symbol.hpp"
32 #include "prims/jni.h"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "trace/traceMacros.hpp"
36 #include "utilities/events.hpp"
37 #include "utilities/growableArray.hpp"
38 #include "utilities/hashtable.inline.hpp"
39 #include "utilities/ostream.hpp"
40
41 ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
42
43 void ModuleEntry::set_location(Symbol* location) {
44 if (_location != NULL) {
45 // _location symbol's refcounts are managed by ModuleEntry,
46 // must decrement the old one before updating.
47 _location->decrement_refcount();
48 }
49
50 _location = location;
51
52 if (location != NULL) {
53 location->increment_refcount();
54 }
55 }
56
57 bool ModuleEntry::is_non_jdk_module() {
58 ResourceMark rm;
59 if (location() != NULL) {
60 const char* loc = location()->as_C_string();
61 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) {
62 return true;
63 }
64 }
65 return false;
66 }
67
68 void ModuleEntry::set_version(Symbol* version) {
69 if (_version != NULL) {
70 // _version symbol's refcounts are managed by ModuleEntry,
71 // must decrement the old one before updating.
72 _version->decrement_refcount();
73 }
74
75 _version = version;
76
77 if (version != NULL) {
78 version->increment_refcount();
79 }
80 }
81
82 // Returns the shared ProtectionDomain
83 Handle ModuleEntry::shared_protection_domain() {
84 return Handle(JNIHandles::resolve(_pd));
85 }
86
87 // Set the shared ProtectionDomain atomically
88 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
89 Handle pd_h) {
90 // Create a JNI handle for the shared ProtectionDomain and save it atomically.
91 // If someone beats us setting the _pd cache, the created JNI handle is destroyed.
92 jobject obj = loader_data->add_handle(pd_h);
93 if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) {
94 loader_data->remove_handle(obj);
95 }
96 }
97
98 // Returns true if this module can read module m
99 bool ModuleEntry::can_read(ModuleEntry* m) const {
100 assert(m != NULL, "No module to lookup in this module's reads list");
101
102 // Unnamed modules read everyone and all modules
103 // read java.base. If either of these conditions
104 // hold, readability has been established.
105 if (!this->is_named() ||
106 (m == ModuleEntryTable::javabase_moduleEntry())) {
107 return true;
108 }
109
110 MutexLocker m1(Module_lock);
111 // This is a guard against possible race between agent threads that redefine
112 // or retransform classes in this module. Only one of them is adding the
113 // default read edges to the unnamed modules of the boot and app class loaders
114 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
115 // At the same time, another thread can instrument the module classes by
116 // injecting dependencies that require the default read edges for resolution.
117 if (this->has_default_read_edges() && !m->is_named()) {
118 ClassLoaderData* cld = m->loader_data();
119 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
120 return true; // default read edge
121 }
122 }
123 if (!has_reads()) {
124 return false;
125 } else {
126 return _reads->contains(m);
127 }
128 }
129
130 // Add a new module to this module's reads list
131 void ModuleEntry::add_read(ModuleEntry* m) {
132 MutexLocker m1(Module_lock);
133 if (m == NULL) {
134 set_can_read_all_unnamed();
135 } else {
136 if (_reads == NULL) {
137 // Lazily create a module's reads list
138 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
139 }
140
141 // Determine, based on this newly established read edge to module m,
142 // if this module's read list should be walked at a GC safepoint.
143 set_read_walk_required(m->loader_data());
144
145 // Establish readability to module m
146 _reads->append_if_missing(m);
147 }
148 }
149
150 // If the module's loader, that a read edge is being established to, is
151 // not the same loader as this module's and is not one of the 3 builtin
152 // class loaders, then this module's reads list must be walked at GC
153 // safepoint. Modules have the same life cycle as their defining class
154 // loaders and should be removed if dead.
155 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
156 assert_locked_or_safepoint(Module_lock);
157 if (!_must_walk_reads &&
158 loader_data() != m_loader_data &&
159 !m_loader_data->is_builtin_class_loader_data()) {
160 _must_walk_reads = true;
161 if (log_is_enabled(Trace, modules)) {
162 ResourceMark rm;
163 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
164 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
165 }
166 }
167 }
168
169 bool ModuleEntry::has_reads() const {
170 return ((_reads != NULL) && !_reads->is_empty());
171 }
172
173 // Purge dead module entries out of reads list.
174 void ModuleEntry::purge_reads() {
175 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
176
177 if (_must_walk_reads && has_reads()) {
178 // This module's _must_walk_reads flag will be reset based
179 // on the remaining live modules on the reads list.
180 _must_walk_reads = false;
181
182 if (log_is_enabled(Trace, modules)) {
183 ResourceMark rm;
184 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
185 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
186 }
187
188 // Go backwards because this removes entries that are dead.
189 int len = _reads->length();
190 for (int idx = len - 1; idx >= 0; idx--) {
191 ModuleEntry* module_idx = _reads->at(idx);
192 ClassLoaderData* cld_idx = module_idx->loader_data();
193 if (cld_idx->is_unloading()) {
194 _reads->delete_at(idx);
195 } else {
196 // Update the need to walk this module's reads based on live modules
197 set_read_walk_required(cld_idx);
198 }
199 }
200 }
201 }
202
203 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
204 assert(f != NULL, "invariant");
205 if (has_reads()) {
206 int reads_len = _reads->length();
207 for (int i = 0; i < reads_len; ++i) {
208 f->do_module(_reads->at(i));
209 }
210 }
211 }
212
213 void ModuleEntry::delete_reads() {
214 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
215 delete _reads;
216 _reads = NULL;
217 }
218
219 ModuleEntryTable::ModuleEntryTable(int table_size)
220 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL)
221 {
222 }
223
224 ModuleEntryTable::~ModuleEntryTable() {
225 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
226
227 // Walk through all buckets and all entries in each bucket,
228 // freeing each entry.
229 for (int i = 0; i < table_size(); ++i) {
230 for (ModuleEntry* m = bucket(i); m != NULL;) {
231 ModuleEntry* to_remove = m;
232 // read next before freeing.
233 m = m->next();
234
235 ResourceMark rm;
236 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
237 to_remove->name()->as_C_string() : UNNAMED_MODULE);
238
239 // Clean out the C heap allocated reads list first before freeing the entry
240 to_remove->delete_reads();
241 if (to_remove->name() != NULL) {
242 to_remove->name()->decrement_refcount();
243 }
244 if (to_remove->version() != NULL) {
245 to_remove->version()->decrement_refcount();
246 }
247 if (to_remove->location() != NULL) {
248 to_remove->location()->decrement_refcount();
249 }
250
251 // Unlink from the Hashtable prior to freeing
252 unlink_entry(to_remove);
253 FREE_C_HEAP_ARRAY(char, to_remove);
254 }
255 }
256 assert(number_of_entries() == 0, "should have removed all entries");
257 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
258 free_buckets();
259 }
260
261 void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) {
262 assert(Module_lock->owned_by_self(), "should have the Module_lock");
263
264 // Each ModuleEntryTable has exactly one unnamed module
265 if (loader_data->is_the_null_class_loader_data()) {
266 // For the boot loader, the java.lang.reflect.Module for the unnamed module
267 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
268 // this point initially create the ModuleEntry for the unnamed module.
269 _unnamed_module = new_entry(0, Handle(NULL), NULL, NULL, NULL, loader_data);
270 } else {
271 // For all other class loaders the java.lang.reflect.Module for their
272 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
273 oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader());
274 _unnamed_module = new_entry(0, Handle(module), NULL, NULL, NULL, loader_data);
275
276 // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module
277 // object.
278 java_lang_reflect_Module::set_module_entry(module, _unnamed_module);
279 }
280
281 // Add to bucket 0, no name to hash on
282 add_entry(0, _unnamed_module);
283 }
284
285 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, Symbol* name,
286 Symbol* version, Symbol* location,
287 ClassLoaderData* loader_data) {
288 assert(Module_lock->owned_by_self(), "should have the Module_lock");
289 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
290
291 // Initialize everything BasicHashtable would
292 entry->set_next(NULL);
293 entry->set_hash(hash);
294 entry->set_literal(name);
295
296 // Initialize fields specific to a ModuleEntry
297 entry->init();
298 if (name != NULL) {
299 name->increment_refcount();
300 } else {
301 // Unnamed modules can read all other unnamed modules.
302 entry->set_can_read_all_unnamed();
303 }
304
305 if (!module_handle.is_null()) {
306 entry->set_module(loader_data->add_handle(module_handle));
307 }
308
309 entry->set_loader_data(loader_data);
310 entry->set_version(version);
311 entry->set_location(location);
312
313 if (ClassLoader::is_in_patch_mod_entries(name)) {
314 entry->set_is_patched();
315 if (log_is_enabled(Trace, modules, patch)) {
316 ResourceMark rm;
317 log_trace(modules, patch)("Marked module %s as patched from --patch-module", name->as_C_string());
318 }
319 }
320
321 TRACE_INIT_ID(entry);
322
323 return entry;
324 }
325
326 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
327 assert(Module_lock->owned_by_self(), "should have the Module_lock");
328 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
329 }
330
331 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
332 Symbol* module_name,
333 Symbol* module_version,
334 Symbol* module_location,
335 ClassLoaderData* loader_data) {
336 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
337 assert(Module_lock->owned_by_self(), "should have the Module_lock");
338 // Check if module already exists.
339 if (lookup_only(module_name) != NULL) {
340 return NULL;
341 } else {
342 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, module_name,
343 module_version, module_location, loader_data);
344 add_entry(index_for(module_name), entry);
345 return entry;
346 }
347 }
348
349 // lookup_only by Symbol* to find a ModuleEntry.
350 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
351 if (name == NULL) {
352 // Return this table's unnamed module
353 return unnamed_module();
354 }
355 int index = index_for(name);
356 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
357 if (m->name()->fast_compare(name) == 0) {
358 return m;
359 }
360 }
361 return NULL;
362 }
363
364 // Remove dead modules from all other alive modules' reads list.
365 // This should only occur at class unloading.
366 void ModuleEntryTable::purge_all_module_reads() {
367 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
368 for (int i = 0; i < table_size(); i++) {
369 for (ModuleEntry* entry = bucket(i);
370 entry != NULL;
371 entry = entry->next()) {
372 entry->purge_reads();
373 }
374 }
375 }
376
377 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
378 assert(Module_lock->owned_by_self(), "should have the Module_lock");
379 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
380 ModuleEntryTable* module_table = boot_loader_data->modules();
381
382 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
383
384 if (module_handle.is_null()) {
385 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
386 }
387
388 // Set java.lang.reflect.Module, version and location for java.base
389 ModuleEntry* jb_module = javabase_moduleEntry();
390 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
391 jb_module->set_version(version);
392 jb_module->set_location(location);
393 // Once java.base's ModuleEntry _module field is set with the known
394 // java.lang.reflect.Module, java.base is considered "defined" to the VM.
395 jb_module->set_module(boot_loader_data->add_handle(module_handle));
396
397 // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object.
398 java_lang_reflect_Module::set_module_entry(module_handle(), jb_module);
399 }
400
401 // Within java.lang.Class instances there is a java.lang.reflect.Module field
402 // that must be set with the defining module. During startup, prior to java.base's
403 // definition, classes needing their module field set are added to the fixup_module_list.
404 // Their module field is set once java.base's java.lang.reflect.Module is known to the VM.
405 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
406 if (module_handle.is_null()) {
407 fatal("Unable to patch the module field of classes loaded prior to "
408 JAVA_BASE_NAME "'s definition, invalid java.lang.reflect.Module");
409 }
410
411 // Do the fixups for the basic primitive types
412 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
413 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
414 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
415 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
416 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
417 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
418 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
419 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
420 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
421
422 // Do the fixups for classes that have already been created.
423 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
424 int list_length = list->length();
425 for (int i = 0; i < list_length; i++) {
426 Klass* k = list->at(i);
427 assert(k->is_klass(), "List should only hold classes");
428 java_lang_Class::fixup_module_field(KlassHandle(k), module_handle);
429 k->class_loader_data()->dec_keep_alive();
430 }
431
432 delete java_lang_Class::fixup_module_field_list();
433 java_lang_Class::set_fixup_module_field_list(NULL);
434 }
435
436 void ModuleEntryTable::print(outputStream* st) {
437 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
438 table_size(), number_of_entries());
439 for (int i = 0; i < table_size(); i++) {
440 for (ModuleEntry* probe = bucket(i);
441 probe != NULL;
442 probe = probe->next()) {
443 probe->print(st);
444 }
445 }
446 }
447
448 void ModuleEntry::print(outputStream* st) {
449 ResourceMark rm;
450 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
451 p2i(this),
452 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
453 p2i(module()),
454 loader_data()->loader_name(),
455 version() != NULL ? version()->as_C_string() : "NULL",
456 location() != NULL ? location()->as_C_string() : "NULL",
457 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
458 }
459
460 void ModuleEntryTable::verify() {
461 int element_count = 0;
462 for (int i = 0; i < table_size(); i++) {
463 for (ModuleEntry* probe = bucket(i);
464 probe != NULL;
465 probe = probe->next()) {
466 probe->verify();
467 element_count++;
468 }
469 }
470 guarantee(number_of_entries() == element_count,
471 "Verify of Module Entry Table failed");
472 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table"));
473 }
474
475 void ModuleEntry::verify() {
476 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
477 }