1 /*
2 * Copyright (c) 2016, 2017, 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 oop ModuleEntry::shared_protection_domain() {
84 return _pd.resolve();
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 handle for the shared ProtectionDomain and save it atomically.
91 // init_handle_locked checks if someone beats us setting the _pd cache.
92 loader_data->init_handle_locked(_pd, pd_h);
93 }
94
95 // Returns true if this module can read module m
96 bool ModuleEntry::can_read(ModuleEntry* m) const {
97 assert(m != NULL, "No module to lookup in this module's reads list");
98
99 // Unnamed modules read everyone and all modules
100 // read java.base. If either of these conditions
101 // hold, readability has been established.
102 if (!this->is_named() ||
103 (m == ModuleEntryTable::javabase_moduleEntry())) {
104 return true;
105 }
106
107 MutexLocker m1(Module_lock);
108 // This is a guard against possible race between agent threads that redefine
109 // or retransform classes in this module. Only one of them is adding the
110 // default read edges to the unnamed modules of the boot and app class loaders
111 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
112 // At the same time, another thread can instrument the module classes by
113 // injecting dependencies that require the default read edges for resolution.
114 if (this->has_default_read_edges() && !m->is_named()) {
115 ClassLoaderData* cld = m->loader_data();
116 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
117 return true; // default read edge
118 }
119 }
120 if (!has_reads_list()) {
121 return false;
122 } else {
123 return _reads->contains(m);
124 }
125 }
126
127 // Add a new module to this module's reads list
128 void ModuleEntry::add_read(ModuleEntry* m) {
129 // Unnamed module is special cased and can read all modules
130 if (!is_named()) {
131 return;
132 }
133
134 MutexLocker m1(Module_lock);
135 if (m == NULL) {
136 set_can_read_all_unnamed();
137 } else {
138 if (_reads == NULL) {
139 // Lazily create a module's reads list
140 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
141 }
142
143 // Determine, based on this newly established read edge to module m,
144 // if this module's read list should be walked at a GC safepoint.
145 set_read_walk_required(m->loader_data());
146
147 // Establish readability to module m
148 _reads->append_if_missing(m);
149 }
150 }
151
152 // If the module's loader, that a read edge is being established to, is
153 // not the same loader as this module's and is not one of the 3 builtin
154 // class loaders, then this module's reads list must be walked at GC
155 // safepoint. Modules have the same life cycle as their defining class
156 // loaders and should be removed if dead.
157 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
158 assert(is_named(), "Cannot call set_read_walk_required on unnamed module");
159 assert_locked_or_safepoint(Module_lock);
160 if (!_must_walk_reads &&
161 loader_data() != m_loader_data &&
162 !m_loader_data->is_builtin_class_loader_data()) {
163 _must_walk_reads = true;
164 if (log_is_enabled(Trace, module)) {
165 ResourceMark rm;
166 log_trace(module)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
167 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
168 }
169 }
170 }
171
172 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
173 void ModuleEntry::set_is_open(bool is_open) {
174 assert_lock_strong(Module_lock);
175 _is_open = is_open;
176 }
177
178 // Returns true if the module has a non-empty reads list. As such, the unnamed
179 // module will return false.
180 bool ModuleEntry::has_reads_list() const {
181 assert_locked_or_safepoint(Module_lock);
182 return ((_reads != NULL) && !_reads->is_empty());
183 }
184
185 // Purge dead module entries out of reads list.
186 void ModuleEntry::purge_reads() {
187 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
188
189 if (_must_walk_reads && has_reads_list()) {
190 // This module's _must_walk_reads flag will be reset based
191 // on the remaining live modules on the reads list.
192 _must_walk_reads = false;
193
194 if (log_is_enabled(Trace, module)) {
195 ResourceMark rm;
196 log_trace(module)("ModuleEntry::purge_reads(): module %s reads list being walked",
197 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
198 }
199
200 // Go backwards because this removes entries that are dead.
201 int len = _reads->length();
202 for (int idx = len - 1; idx >= 0; idx--) {
203 ModuleEntry* module_idx = _reads->at(idx);
204 ClassLoaderData* cld_idx = module_idx->loader_data();
205 if (cld_idx->is_unloading()) {
206 _reads->delete_at(idx);
207 } else {
208 // Update the need to walk this module's reads based on live modules
209 set_read_walk_required(cld_idx);
210 }
211 }
212 }
213 }
214
215 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
216 assert_locked_or_safepoint(Module_lock);
217 assert(f != NULL, "invariant");
218
219 if (has_reads_list()) {
220 int reads_len = _reads->length();
221 for (int i = 0; i < reads_len; ++i) {
222 f->do_module(_reads->at(i));
223 }
224 }
225 }
226
227 void ModuleEntry::delete_reads() {
228 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
229 delete _reads;
230 _reads = NULL;
231 }
232
233 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
234 // The java.lang.Module for this loader's
235 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
236 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
237 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
238
239 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module
240 // object.
241 java_lang_Module::set_module_entry(module, unnamed_module);
242
243 return unnamed_module;
244 }
245
246 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
247 // For the boot loader, the java.lang.Module for the unnamed module
248 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
249 // this point initially create the ModuleEntry for the unnamed module.
250 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
251 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
252 return unnamed_module;
253 }
254
255 // When creating an unnamed module, this is called without holding the Module_lock.
256 // This is okay because the unnamed module gets created before the ClassLoaderData
257 // is available to other threads.
258 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
259 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, sizeof(ModuleEntry), mtModule);
260
261 // Initialize everything BasicHashtable would
262 entry->set_next(NULL);
263 entry->set_hash(0);
264 entry->set_literal(NULL);
265
266 // Initialize fields specific to a ModuleEntry
267 entry->init();
268
269 // Unnamed modules can read all other unnamed modules.
270 entry->set_can_read_all_unnamed();
271
272 if (!module_handle.is_null()) {
273 entry->set_module(cld->add_handle(module_handle));
274 }
275
276 entry->set_loader_data(cld);
277 entry->_is_open = true;
278
279 TRACE_INIT_ID(entry);
280
281 return entry;
282 }
283
284 void ModuleEntry::delete_unnamed_module() {
285 // Do not need unlink_entry() since the unnamed module is not in the hashtable
286 FREE_C_HEAP_ARRAY(char, this);
287 }
288
289 ModuleEntryTable::ModuleEntryTable(int table_size)
290 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
291 {
292 }
293
294 ModuleEntryTable::~ModuleEntryTable() {
295 assert_locked_or_safepoint(Module_lock);
296
297 // Walk through all buckets and all entries in each bucket,
298 // freeing each entry.
299 for (int i = 0; i < table_size(); ++i) {
300 for (ModuleEntry* m = bucket(i); m != NULL;) {
301 ModuleEntry* to_remove = m;
302 // read next before freeing.
303 m = m->next();
304
305 ResourceMark rm;
306 if (to_remove->name() != NULL) {
307 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string());
308 }
309 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
310 to_remove->name()->as_C_string() : UNNAMED_MODULE);
311
312 // Clean out the C heap allocated reads list first before freeing the entry
313 to_remove->delete_reads();
314 if (to_remove->name() != NULL) {
315 to_remove->name()->decrement_refcount();
316 }
317 if (to_remove->version() != NULL) {
318 to_remove->version()->decrement_refcount();
319 }
320 if (to_remove->location() != NULL) {
321 to_remove->location()->decrement_refcount();
322 }
323
324 // Unlink from the Hashtable prior to freeing
325 unlink_entry(to_remove);
326 FREE_C_HEAP_ARRAY(char, to_remove);
327 }
328 }
329 assert(number_of_entries() == 0, "should have removed all entries");
330 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
331 free_buckets();
332 }
333
334 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
335 bool is_open, Symbol* name,
336 Symbol* version, Symbol* location,
337 ClassLoaderData* loader_data) {
338 assert(Module_lock->owned_by_self(), "should have the Module_lock");
339 ModuleEntry* entry = (ModuleEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);
340
341 // Initialize fields specific to a ModuleEntry
342 entry->init();
343 if (name != NULL) {
344 name->increment_refcount();
345 } else {
346 // Unnamed modules can read all other unnamed modules.
347 entry->set_can_read_all_unnamed();
348 }
349
350 if (!module_handle.is_null()) {
351 entry->set_module(loader_data->add_handle(module_handle));
352 }
353
354 entry->set_loader_data(loader_data);
355 entry->set_version(version);
356 entry->set_location(location);
357 entry->set_is_open(is_open);
358
359 if (ClassLoader::is_in_patch_mod_entries(name)) {
360 entry->set_is_patched();
361 if (log_is_enabled(Trace, module, patch)) {
362 ResourceMark rm;
363 log_trace(module, patch)("Marked module %s as patched from --patch-module", name->as_C_string());
364 }
365 }
366
367 TRACE_INIT_ID(entry);
368
369 return entry;
370 }
371
372 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
373 assert(Module_lock->owned_by_self(), "should have the Module_lock");
374 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
375 }
376
377 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
378 bool is_open,
379 Symbol* module_name,
380 Symbol* module_version,
381 Symbol* module_location,
382 ClassLoaderData* loader_data) {
383 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
384 assert(Module_lock->owned_by_self(), "should have the Module_lock");
385 // Check if module already exists.
386 if (lookup_only(module_name) != NULL) {
387 return NULL;
388 } else {
389 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
390 module_version, module_location, loader_data);
391 add_entry(index_for(module_name), entry);
392 return entry;
393 }
394 }
395
396 // lookup_only by Symbol* to find a ModuleEntry.
397 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
398 assert(name != NULL, "name cannot be NULL");
399 int index = index_for(name);
400 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
401 if (m->name()->fast_compare(name) == 0) {
402 return m;
403 }
404 }
405 return NULL;
406 }
407
408 // Remove dead modules from all other alive modules' reads list.
409 // This should only occur at class unloading.
410 void ModuleEntryTable::purge_all_module_reads() {
411 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
412 for (int i = 0; i < table_size(); i++) {
413 for (ModuleEntry* entry = bucket(i);
414 entry != NULL;
415 entry = entry->next()) {
416 entry->purge_reads();
417 }
418 }
419 }
420
421 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
422 assert(Module_lock->owned_by_self(), "should have the Module_lock");
423 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
424 ModuleEntryTable* module_table = boot_loader_data->modules();
425
426 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
427
428 if (module_handle.is_null()) {
429 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
430 }
431
432 // Set java.lang.Module, version and location for java.base
433 ModuleEntry* jb_module = javabase_moduleEntry();
434 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
435 jb_module->set_version(version);
436 jb_module->set_location(location);
437 // Once java.base's ModuleEntry _module field is set with the known
438 // java.lang.Module, java.base is considered "defined" to the VM.
439 jb_module->set_module(boot_loader_data->add_handle(module_handle));
440
441 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object.
442 java_lang_Module::set_module_entry(module_handle(), jb_module);
443 }
444
445 // Within java.lang.Class instances there is a java.lang.Module field that must
446 // be set with the defining module. During startup, prior to java.base's definition,
447 // classes needing their module field set are added to the fixup_module_list.
448 // Their module field is set once java.base's java.lang.Module is known to the VM.
449 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
450 if (module_handle.is_null()) {
451 fatal("Unable to patch the module field of classes loaded prior to "
452 JAVA_BASE_NAME "'s definition, invalid java.lang.Module");
453 }
454
455 // Do the fixups for the basic primitive types
456 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
457 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
458 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
459 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
460 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
461 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
462 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
463 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
464 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
465
466 // Do the fixups for classes that have already been created.
467 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
468 int list_length = list->length();
469 for (int i = 0; i < list_length; i++) {
470 Klass* k = list->at(i);
471 assert(k->is_klass(), "List should only hold classes");
472 java_lang_Class::fixup_module_field(k, module_handle);
473 k->class_loader_data()->dec_keep_alive();
474 }
475
476 delete java_lang_Class::fixup_module_field_list();
477 java_lang_Class::set_fixup_module_field_list(NULL);
478 }
479
480 void ModuleEntryTable::print(outputStream* st) {
481 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
482 table_size(), number_of_entries());
483 for (int i = 0; i < table_size(); i++) {
484 for (ModuleEntry* probe = bucket(i);
485 probe != NULL;
486 probe = probe->next()) {
487 probe->print(st);
488 }
489 }
490 }
491
492 void ModuleEntry::print(outputStream* st) {
493 ResourceMark rm;
494 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
495 p2i(this),
496 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
497 p2i(module()),
498 loader_data()->loader_name(),
499 version() != NULL ? version()->as_C_string() : "NULL",
500 location() != NULL ? location()->as_C_string() : "NULL",
501 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
502 }
503
504 void ModuleEntryTable::verify() {
505 verify_table<ModuleEntry>("Module Entry Table");
506 }
507
508 void ModuleEntry::verify() {
509 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
510 }