1 /*
2 * Copyright (c) 2017, 2019, 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 #include "precompiled.hpp"
25 #include "code/relocInfo.hpp"
26 #include "code/nmethod.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/barrierSetNMethod.hpp"
30 #include "gc/z/zGlobals.hpp"
31 #include "gc/z/zHash.inline.hpp"
32 #include "gc/z/zLock.inline.hpp"
33 #include "gc/z/zNMethodAllocator.hpp"
34 #include "gc/z/zNMethodTable.hpp"
35 #include "gc/z/zOopClosures.inline.hpp"
36 #include "gc/z/zTask.hpp"
37 #include "gc/z/zWorkers.hpp"
38 #include "logging/log.hpp"
39 #include "memory/allocation.hpp"
40 #include "memory/resourceArea.hpp"
41 #include "runtime/atomic.hpp"
42 #include "runtime/orderAccess.hpp"
43 #include "utilities/debug.hpp"
44
45 class ZNMethodDataOops {
46 private:
47 const size_t _nimmediates;
48 bool _has_non_immediates;
49
50 static size_t header_size();
51
52 ZNMethodDataOops(const GrowableArray<oop*>& immediates, bool has_non_immediates);
53
54 public:
55 static ZNMethodDataOops* create(const GrowableArray<oop*>& immediates, bool has_non_immediates);
56 static void destroy(ZNMethodDataOops* oops);
57
58 size_t immediates_count() const;
59 oop** immediates_begin() const;
60 oop** immediates_end() const;
61
62 bool has_non_immediates() const;
63 };
64
65 size_t ZNMethodDataOops::header_size() {
66 const size_t size = sizeof(ZNMethodDataOops);
67 assert(is_aligned(size, sizeof(oop*)), "Header misaligned");
68 return size;
69 }
70
71 ZNMethodDataOops* ZNMethodDataOops::create(const GrowableArray<oop*>& immediates, bool has_non_immediates) {
72 // Allocate memory for the ZNMethodDataOops object
73 // plus the immediate oop* array that follows right after.
74 const size_t size = ZNMethodDataOops::header_size() + (sizeof(oop*) * immediates.length());
75 void* const mem = ZNMethodAllocator::allocate(size);
76 return ::new (mem) ZNMethodDataOops(immediates, has_non_immediates);
77 }
78
79 void ZNMethodDataOops::destroy(ZNMethodDataOops* oops) {
80 ZNMethodAllocator::free(oops);
81 }
82
83 ZNMethodDataOops::ZNMethodDataOops(const GrowableArray<oop*>& immediates, bool has_non_immediates) :
84 _nimmediates(immediates.length()),
85 _has_non_immediates(has_non_immediates) {
86 // Save all immediate oops
87 for (size_t i = 0; i < _nimmediates; i++) {
88 immediates_begin()[i] = immediates.at(i);
89 }
90 }
91
92 size_t ZNMethodDataOops::immediates_count() const {
93 return _nimmediates;
94 }
95
96 oop** ZNMethodDataOops::immediates_begin() const {
97 // The immediate oop* array starts immediately after this object
98 return (oop**)((uintptr_t)this + header_size());
99 }
100
101 oop** ZNMethodDataOops::immediates_end() const {
102 return immediates_begin() + immediates_count();
103 }
104
105 bool ZNMethodDataOops::has_non_immediates() const {
106 return _has_non_immediates;
107 }
108
109 class ZNMethodData {
110 private:
111 ZReentrantLock _lock;
112 ZNMethodDataOops* volatile _oops;
113
114 ZNMethodData(nmethod* nm);
115
116 public:
117 static ZNMethodData* create(nmethod* nm);
118 static void destroy(ZNMethodData* data);
119
120 ZReentrantLock* lock();
121
122 ZNMethodDataOops* oops() const;
123 ZNMethodDataOops* swap_oops(ZNMethodDataOops* oops);
124 };
125
126 ZNMethodData* ZNMethodData::create(nmethod* nm) {
127 void* const mem = ZNMethodAllocator::allocate(sizeof(ZNMethodData));
128 return ::new (mem) ZNMethodData(nm);
129 }
130
131 void ZNMethodData::destroy(ZNMethodData* data) {
132 ZNMethodAllocator::free(data->oops());
133 ZNMethodAllocator::free(data);
134 }
135
136 ZNMethodData::ZNMethodData(nmethod* nm) :
137 _lock(),
138 _oops(NULL) {}
139
140 ZReentrantLock* ZNMethodData::lock() {
141 return &_lock;
142 }
143
144 ZNMethodDataOops* ZNMethodData::oops() const {
145 return OrderAccess::load_acquire(&_oops);
146 }
147
148 ZNMethodDataOops* ZNMethodData::swap_oops(ZNMethodDataOops* new_oops) {
149 return Atomic::xchg(new_oops, &_oops);
150 }
151
152 static ZNMethodData* gc_data(const nmethod* nm) {
153 return nm->gc_data<ZNMethodData>();
154 }
155
156 static void set_gc_data(nmethod* nm, ZNMethodData* data) {
157 return nm->set_gc_data<ZNMethodData>(data);
158 }
159
160 ZNMethodTableEntry* ZNMethodTable::_table = NULL;
161 size_t ZNMethodTable::_size = 0;
162 ZNMethodTableEntry* ZNMethodTable::_iter_table = NULL;
163 size_t ZNMethodTable::_iter_table_size = 0;
164 size_t ZNMethodTable::_nregistered = 0;
165 size_t ZNMethodTable::_nunregistered = 0;
166 volatile size_t ZNMethodTable::_claimed = 0;
167
168 void ZNMethodTable::attach_gc_data(nmethod* nm) {
169 GrowableArray<oop*> immediate_oops;
170 bool non_immediate_oops = false;
171
172 // Find all oops relocations
173 RelocIterator iter(nm);
174 while (iter.next()) {
175 if (iter.type() != relocInfo::oop_type) {
176 // Not an oop
177 continue;
178 }
179
180 oop_Relocation* r = iter.oop_reloc();
181
182 if (!r->oop_is_immediate()) {
183 // Non-immediate oop found
184 non_immediate_oops = true;
185 continue;
186 }
187
188 if (r->oop_value() != NULL) {
189 // Non-NULL immediate oop found. NULL oops can safely be
190 // ignored since the method will be re-registered if they
191 // are later patched to be non-NULL.
192 immediate_oops.push(r->oop_addr());
193 }
194 }
195
196 // Attach GC data to nmethod
197 ZNMethodData* data = gc_data(nm);
198 if (data == NULL) {
199 data = ZNMethodData::create(nm);
200 set_gc_data(nm, data);
201 }
202
203 // Attach oops in GC data
204 ZNMethodDataOops* const new_oops = ZNMethodDataOops::create(immediate_oops, non_immediate_oops);
205 ZNMethodDataOops* const old_oops = data->swap_oops(new_oops);
206 ZNMethodDataOops::destroy(old_oops);
207 }
208
209 void ZNMethodTable::detach_gc_data(nmethod* nm) {
210 // Destroy GC data
211 ZNMethodData::destroy(gc_data(nm));
212 set_gc_data(nm, NULL);
213 }
214
215 ZReentrantLock* ZNMethodTable::lock_for_nmethod(nmethod* nm) {
216 ZNMethodData* const data = gc_data(nm);
217 if (data == NULL) {
218 return NULL;
219 }
220 return data->lock();
221 }
222
223 size_t ZNMethodTable::first_index(const nmethod* nm, size_t size) {
224 assert(is_power_of_2(size), "Invalid size");
225 const size_t mask = size - 1;
226 const size_t hash = ZHash::address_to_uint32((uintptr_t)nm);
227 return hash & mask;
228 }
229
230 size_t ZNMethodTable::next_index(size_t prev_index, size_t size) {
231 assert(is_power_of_2(size), "Invalid size");
232 const size_t mask = size - 1;
233 return (prev_index + 1) & mask;
234 }
235
236 bool ZNMethodTable::register_entry(ZNMethodTableEntry* table, size_t size, nmethod* nm) {
237 const ZNMethodTableEntry entry(nm);
238 size_t index = first_index(nm, size);
239
240 for (;;) {
241 const ZNMethodTableEntry table_entry = table[index];
242
243 if (!table_entry.registered() && !table_entry.unregistered()) {
244 // Insert new entry
245 table[index] = entry;
246 return true;
247 }
248
249 if (table_entry.registered() && table_entry.method() == nm) {
250 // Replace existing entry
251 table[index] = entry;
252 return false;
253 }
254
255 index = next_index(index, size);
256 }
257 }
258
259 void ZNMethodTable::unregister_entry(ZNMethodTableEntry* table, size_t size, nmethod* nm) {
260 size_t index = first_index(nm, size);
261
262 for (;;) {
263 const ZNMethodTableEntry table_entry = table[index];
264 assert(table_entry.registered() || table_entry.unregistered(), "Entry not found");
265
266 if (table_entry.registered() && table_entry.method() == nm) {
267 // Remove entry
268 table[index] = ZNMethodTableEntry(true /* unregistered */);
269 return;
270 }
271
272 index = next_index(index, size);
273 }
274 }
275
276 void ZNMethodTable::rebuild(size_t new_size) {
277 assert(CodeCache_lock->owned_by_self(), "Lock must be held");
278
279 assert(is_power_of_2(new_size), "Invalid size");
280
281 log_debug(gc, nmethod)("Rebuilding NMethod Table: "
282 SIZE_FORMAT "->" SIZE_FORMAT " entries, "
283 SIZE_FORMAT "(%.0lf%%->%.0lf%%) registered, "
284 SIZE_FORMAT "(%.0lf%%->%.0lf%%) unregistered",
285 _size, new_size,
286 _nregistered, percent_of(_nregistered, _size), percent_of(_nregistered, new_size),
287 _nunregistered, percent_of(_nunregistered, _size), 0.0);
288
289 // Allocate new table
290 ZNMethodTableEntry* const new_table = new ZNMethodTableEntry[new_size];
291
292 // Transfer all registered entries
293 for (size_t i = 0; i < _size; i++) {
294 const ZNMethodTableEntry entry = _table[i];
295 if (entry.registered()) {
296 register_entry(new_table, new_size, entry.method());
297 }
298 }
299
300 if (_iter_table != _table) {
301 // Delete old table
302 delete [] _table;
303 }
304
305 // Install new table
306 _table = new_table;
307 _size = new_size;
308 _nunregistered = 0;
309 }
310
311 void ZNMethodTable::rebuild_if_needed() {
312 // The hash table uses linear probing. To avoid wasting memory while
313 // at the same time maintaining good hash collision behavior we want
314 // to keep the table occupancy between 30% and 70%. The table always
315 // grows/shrinks by doubling/halving its size. Pruning of unregistered
316 // entries is done by rebuilding the table with or without resizing it.
317 const size_t min_size = 1024;
318 const size_t shrink_threshold = _size * 0.30;
319 const size_t prune_threshold = _size * 0.65;
320 const size_t grow_threshold = _size * 0.70;
321
322 if (_size == 0) {
323 // Initialize table
324 rebuild(min_size);
325 } else if (_nregistered < shrink_threshold && _size > min_size) {
326 // Shrink table
327 rebuild(_size / 2);
328 } else if (_nregistered + _nunregistered > grow_threshold) {
329 // Prune or grow table
330 if (_nregistered < prune_threshold) {
331 // Prune table
332 rebuild(_size);
333 } else {
334 // Grow table
335 rebuild(_size * 2);
336 }
337 }
338 }
339
340 void ZNMethodTable::log_register(const nmethod* nm) {
341 LogTarget(Trace, gc, nmethod) log;
342 if (!log.is_enabled()) {
343 return;
344 }
345
346 const ZNMethodDataOops* const oops = gc_data(nm)->oops();
347
348 log.print("Register NMethod: %s.%s (" PTR_FORMAT "), "
349 "Compiler: %s, Oops: %d, ImmediateOops: " SIZE_FORMAT ", NonImmediateOops: %s",
350 nm->method()->method_holder()->external_name(),
351 nm->method()->name()->as_C_string(),
352 p2i(nm),
353 nm->compiler_name(),
354 nm->oops_count() - 1,
355 oops->immediates_count(),
356 oops->has_non_immediates() ? "Yes" : "No");
357
358 LogTarget(Trace, gc, nmethod, oops) log_oops;
359 if (!log_oops.is_enabled()) {
360 return;
361 }
362
363 // Print nmethod oops table
364 oop* const begin = nm->oops_begin();
365 oop* const end = nm->oops_end();
366 for (oop* p = begin; p < end; p++) {
367 log_oops.print(" Oop[" SIZE_FORMAT "] " PTR_FORMAT " (%s)",
368 (p - begin), p2i(*p), (*p)->klass()->external_name());
369 }
370
371 // Print nmethod immediate oops
372 if (oops->immediates_count() > 0) {
373 oop** const begin = oops->immediates_begin();
374 oop** const end = oops->immediates_end();
375 for (oop** p = begin; p < end; p++) {
376 log_oops.print(" ImmediateOop[" SIZE_FORMAT "] " PTR_FORMAT " @ " PTR_FORMAT " (%s)",
377 (p - begin), p2i(**p), p2i(*p), (**p)->klass()->external_name());
378 }
379 }
380 }
381
382 void ZNMethodTable::log_unregister(const nmethod* nm) {
383 LogTarget(Debug, gc, nmethod) log;
384 if (!log.is_enabled()) {
385 return;
386 }
387
388 log.print("Unregister NMethod: %s.%s (" PTR_FORMAT ")",
389 nm->method()->method_holder()->external_name(),
390 nm->method()->name()->as_C_string(),
391 p2i(nm));
392 }
393
394 size_t ZNMethodTable::registered_nmethods() {
395 return _nregistered;
396 }
397
398 size_t ZNMethodTable::unregistered_nmethods() {
399 return _nunregistered;
400 }
401
402 void ZNMethodTable::register_nmethod(nmethod* nm) {
403 assert(CodeCache_lock->owned_by_self(), "Lock must be held");
404 ResourceMark rm;
405
406 // Grow/Shrink/Prune table if needed
407 rebuild_if_needed();
408
409 // Create and attach gc data
410 attach_gc_data(nm);
411
412 log_register(nm);
413
414 // Insert new entry
415 if (register_entry(_table, _size, nm)) {
416 // New entry registered. When register_entry() instead returns
417 // false the nmethod was already in the table so we do not want
418 // to increase number of registered entries in that case.
419 _nregistered++;
420 }
421
422 // Disarm nmethod entry barrier
423 disarm_nmethod(nm);
424 }
425
426 void ZNMethodTable::wait_until_iteration_done() {
427 assert(CodeCache_lock->owned_by_self(), "Lock must be held");
428
429 while (_iter_table != NULL) {
430 CodeCache_lock->wait(Monitor::_no_safepoint_check_flag);
431 }
432 }
433
434 void ZNMethodTable::unregister_nmethod(nmethod* nm) {
435 assert(CodeCache_lock->owned_by_self(), "Lock must be held");
436
437 if (Thread::current()->is_Code_cache_sweeper_thread()) {
438 // The sweeper must wait for any ongoing iteration to complete
439 // before it can unregister an nmethod.
440 ZNMethodTable::wait_until_iteration_done();
441 }
442
443 ResourceMark rm;
444
445 log_unregister(nm);
446
447 // Remove entry
448 unregister_entry(_table, _size, nm);
449 _nunregistered++;
450 _nregistered--;
451
452 detach_gc_data(nm);
453 }
454
455 void ZNMethodTable::disarm_nmethod(nmethod* nm) {
456 BarrierSetNMethod* const bs = BarrierSet::barrier_set()->barrier_set_nmethod();
457 if (bs != NULL) {
458 bs->disarm(nm);
459 }
460 }
461
462 void ZNMethodTable::nmethods_do_begin() {
463 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
464
465 // Make sure we don't free data while iterating
466 ZNMethodAllocator::activate_deferred_frees();
467
468 // Prepare iteration
469 _iter_table = _table;
470 _iter_table_size = _size;
471 _claimed = 0;
472 }
473
474 void ZNMethodTable::nmethods_do_end() {
475 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
476
477 // Finish iteration
478 if (_iter_table != _table) {
479 delete [] _iter_table;
480 }
481 _iter_table = NULL;
482
483 assert(_claimed >= _iter_table_size, "Failed to claim all table entries");
484
485 // Process deferred frees
486 ZNMethodAllocator::deactivate_and_process_deferred_frees();
487
488 // Notify iteration done
489 CodeCache_lock->notify_all();
490 }
491
492 void ZNMethodTable::oops_do(nmethod* nm, OopClosure* cl) {
493 // Process oops table
494 oop* const begin = nm->oops_begin();
495 oop* const end = nm->oops_end();
496 for (oop* p = begin; p < end; p++) {
497 if (*p != Universe::non_oop_word()) {
498 cl->do_oop(p);
499 }
500 }
501
502 ZNMethodDataOops* const oops = gc_data(nm)->oops();
503
504 // Process immediate oops
505 if (oops->immediates_count() > 0) {
506 oop** const begin = oops->immediates_begin();
507 oop** const end = oops->immediates_end();
508 for (oop** p = begin; p < end; p++) {
509 if (**p != Universe::non_oop_word()) {
510 cl->do_oop(*p);
511 }
512 }
513 }
514
515 // Process non-immediate oops
516 if (oops->has_non_immediates()) {
517 nm->fix_oop_relocations();
518 }
519 }
520
521 class ZNMethodToOopsDo : public ZNMethodClosure {
522 private:
523 OopClosure* _cl;
524
525 public:
526 ZNMethodToOopsDo(OopClosure* cl) :
527 _cl(cl) {}
528
529 void do_nmethod(nmethod* nm) {
530 ZNMethodTable::oops_do(nm, _cl);
531 }
532 };
533
534 void ZNMethodTable::oops_do(OopClosure* cl) {
535 ZNMethodToOopsDo nm_cl(cl);
536 nmethods_do(&nm_cl);
537 }
538
539 void ZNMethodTable::nmethods_do(ZNMethodClosure* cl) {
540 for (;;) {
541 // Claim table partition. Each partition is currently sized to span
542 // two cache lines. This number is just a guess, but seems to work well.
543 const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);
544 const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _iter_table_size);
545 const size_t partition_end = MIN2(partition_start + partition_size, _iter_table_size);
546 if (partition_start == partition_end) {
547 // End of table
548 break;
549 }
550
551 // Process table partition
552 for (size_t i = partition_start; i < partition_end; i++) {
553 const ZNMethodTableEntry entry = _iter_table[i];
554 if (entry.registered()) {
555 cl->do_nmethod(entry.method());
556 }
557 }
558 }
559 }
560
561 class ZNMethodTableUnlinkClosure : public ZNMethodClosure {
562 private:
563 bool _unloading_occurred;
564 volatile bool _failed;
565
566 void set_failed() {
567 Atomic::store(true, &_failed);
568 }
569
570 public:
571 ZNMethodTableUnlinkClosure(bool unloading_occurred) :
572 _unloading_occurred(unloading_occurred),
573 _failed(false) {}
574
575 virtual void do_nmethod(nmethod* nm) {
576 if (failed()) {
577 return;
578 }
579
580 if (!nm->is_alive()) {
581 return;
582 }
583
584 ZLocker<ZReentrantLock> locker(ZNMethodTable::lock_for_nmethod(nm));
585
586 if (nm->is_unloading()) {
587 // Unlinking of the dependencies must happen before the
588 // handshake separating unlink and purge.
589 nm->flush_dependencies(false /* delete_immediately */);
590
591 // We don't need to take the lock when unlinking nmethods from
592 // the Method, because it is only concurrently unlinked by
593 // the entry barrier, which acquires the per nmethod lock.
594 nm->unlink_from_method(false /* acquire_lock */);
595 return;
596 }
597
598 // Heal oops and disarm
599 ZNMethodOopClosure cl;
600 ZNMethodTable::oops_do(nm, &cl);
601 ZNMethodTable::disarm_nmethod(nm);
602
603 // Clear compiled ICs and exception caches
604 if (!nm->unload_nmethod_caches(_unloading_occurred)) {
605 set_failed();
606 }
607 }
608
609 bool failed() const {
610 return Atomic::load(&_failed);
611 }
612 };
613
614 class ZNMethodTableUnlinkTask : public ZTask {
615 private:
616 ZNMethodTableUnlinkClosure _cl;
617 ICRefillVerifier* _verifier;
618
619 public:
620 ZNMethodTableUnlinkTask(bool unloading_occurred, ICRefillVerifier* verifier) :
621 ZTask("ZNMethodTableUnlinkTask"),
622 _cl(unloading_occurred),
623 _verifier(verifier) {
624 ZNMethodTable::nmethods_do_begin();
625 }
626
627 ~ZNMethodTableUnlinkTask() {
628 ZNMethodTable::nmethods_do_end();
629 }
630
631 virtual void work() {
632 ICRefillVerifierMark mark(_verifier);
633 ZNMethodTable::nmethods_do(&_cl);
634 }
635
636 bool success() const {
637 return !_cl.failed();
638 }
639 };
640
641 void ZNMethodTable::unlink(ZWorkers* workers, bool unloading_occurred) {
642 for (;;) {
643 ICRefillVerifier verifier;
644
645 {
646 ZNMethodTableUnlinkTask task(unloading_occurred, &verifier);
647 workers->run_concurrent(&task);
648 if (task.success()) {
649 return;
650 }
651 }
652
653 // Cleaning failed because we ran out of transitional IC stubs,
654 // so we have to refill and try again. Refilling requires taking
655 // a safepoint, so we temporarily leave the suspendible thread set.
656 SuspendibleThreadSetLeaver sts;
657 InlineCacheBuffer::refill_ic_stubs();
658 }
659 }
660
661 class ZNMethodTablePurgeClosure : public ZNMethodClosure {
662 public:
663 virtual void do_nmethod(nmethod* nm) {
664 if (nm->is_alive() && nm->is_unloading()) {
665 nm->make_unloaded();
666 }
667 }
668 };
669
670 class ZNMethodTablePurgeTask : public ZTask {
671 private:
672 ZNMethodTablePurgeClosure _cl;
673
674 public:
675 ZNMethodTablePurgeTask() :
676 ZTask("ZNMethodTablePurgeTask"),
677 _cl() {
678 ZNMethodTable::nmethods_do_begin();
679 }
680
681 ~ZNMethodTablePurgeTask() {
682 ZNMethodTable::nmethods_do_end();
683 }
684
685 virtual void work() {
686 ZNMethodTable::nmethods_do(&_cl);
687 }
688 };
689
690 void ZNMethodTable::purge(ZWorkers* workers) {
691 ZNMethodTablePurgeTask task;
692 workers->run_concurrent(&task);
693 }