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