1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2019, 2022, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27
28 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
30 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
31 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "runtime/continuation.hpp"
34 #include "runtime/safepointVerifiers.hpp"
35
36 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>& oops, bool non_immediate_oops) :
37 _nm(nm), _oops(nullptr), _oops_count(0), _unregistered(false) {
38
39 if (!oops.is_empty()) {
40 _oops_count = oops.length();
41 _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);
42 for (int c = 0; c < _oops_count; c++) {
43 _oops[c] = oops.at(c);
44 }
45 }
46 _has_non_immed_oops = non_immediate_oops;
47
48 assert_same_oops();
49 }
50
51 ShenandoahNMethod::~ShenandoahNMethod() {
52 if (_oops != nullptr) {
53 FREE_C_HEAP_ARRAY(oop*, _oops);
54 }
55 }
56
57 void ShenandoahNMethod::update() {
58 ResourceMark rm;
59 bool non_immediate_oops = false;
60 GrowableArray<oop*> oops;
61
62 detect_reloc_oops(nm(), oops, non_immediate_oops);
63 if (oops.length() != _oops_count) {
64 if (_oops != nullptr) {
65 FREE_C_HEAP_ARRAY(oop*, _oops);
66 _oops = nullptr;
67 }
68
69 _oops_count = oops.length();
70 if (_oops_count > 0) {
71 _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);
72 }
73 }
74
75 for (int index = 0; index < _oops_count; index ++) {
76 _oops[index] = oops.at(index);
77 }
78 _has_non_immed_oops = non_immediate_oops;
79
80 assert_same_oops();
81 }
82
83 void ShenandoahNMethod::detect_reloc_oops(nmethod* nm, GrowableArray<oop*>& oops, bool& has_non_immed_oops) {
84 has_non_immed_oops = false;
85 // Find all oops relocations
86 RelocIterator iter(nm);
87 while (iter.next()) {
88 if (iter.type() != relocInfo::oop_type) {
89 // Not an oop
90 continue;
91 }
92
93 oop_Relocation* r = iter.oop_reloc();
94 if (!r->oop_is_immediate()) {
95 // Non-immediate oop found
96 has_non_immed_oops = true;
97 continue;
98 }
99
100 oop value = r->oop_value();
101 if (value != nullptr) {
102 oop* addr = r->oop_addr();
103 shenandoah_assert_correct(addr, value);
104 shenandoah_assert_not_in_cset_except(addr, value, ShenandoahHeap::heap()->cancelled_gc());
105 shenandoah_assert_not_forwarded(addr, value);
106 // Non-null immediate oop found. null oops can safely be
107 // ignored since the method will be re-registered if they
108 // are later patched to be non-null.
109 oops.push(addr);
110 }
111 }
112 }
113
114 ShenandoahNMethod* ShenandoahNMethod::for_nmethod(nmethod* nm) {
115 ResourceMark rm;
116 bool non_immediate_oops = false;
117 GrowableArray<oop*> oops;
118
119 detect_reloc_oops(nm, oops, non_immediate_oops);
120 return new ShenandoahNMethod(nm, oops, non_immediate_oops);
121 }
122
123 void ShenandoahNMethod::heal_nmethod(nmethod* nm) {
124 ShenandoahNMethod* data = gc_data(nm);
125 assert(data != nullptr, "Sanity");
126 assert(data->lock()->owned_by_self(), "Must hold the lock");
127
128 ShenandoahHeap* const heap = ShenandoahHeap::heap();
129 if (heap->is_concurrent_mark_in_progress()) {
130 ShenandoahKeepAliveClosure cl;
131 data->oops_do(&cl);
132 } else if (heap->is_concurrent_weak_root_in_progress() ||
133 heap->is_concurrent_strong_root_in_progress() ) {
134 ShenandoahEvacOOMScope evac_scope;
135 heal_nmethod_metadata(data);
136 } else {
137 // There is possibility that GC is cancelled when it arrives final mark.
138 // In this case, concurrent root phase is skipped and degenerated GC should be
139 // followed, where nmethods are disarmed.
140 }
141 }
142
143 #ifdef ASSERT
144 void ShenandoahNMethod::assert_correct() {
145 ShenandoahHeap* heap = ShenandoahHeap::heap();
146 for (int c = 0; c < _oops_count; c++) {
147 oop *loc = _oops[c];
148 assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
149 oop o = RawAccess<>::oop_load(loc);
150 shenandoah_assert_correct_except(loc, o, o == nullptr || heap->is_full_gc_move_in_progress());
151 }
152
153 oop* const begin = _nm->oops_begin();
154 oop* const end = _nm->oops_end();
155 for (oop* p = begin; p < end; p++) {
156 if (*p != Universe::non_oop_word()) {
157 oop o = RawAccess<>::oop_load(p);
158 shenandoah_assert_correct_except(p, o, o == nullptr || heap->is_full_gc_move_in_progress());
159 }
160 }
161 }
162
163 class ShenandoahNMethodOopDetector : public OopClosure {
164 private:
165 ResourceMark rm; // For growable array allocation below.
166 GrowableArray<oop*> _oops;
167
168 public:
169 ShenandoahNMethodOopDetector() : _oops(10) {};
170
171 void do_oop(oop* o) {
172 _oops.append(o);
173 }
174 void do_oop(narrowOop* o) {
175 fatal("NMethods should not have compressed oops embedded.");
176 }
177
178 GrowableArray<oop*>* oops() {
179 return &_oops;
180 }
181 };
182
183 void ShenandoahNMethod::assert_same_oops(bool allow_dead) {
184 ShenandoahNMethodOopDetector detector;
185 nm()->oops_do(&detector, allow_dead);
186
187 GrowableArray<oop*>* oops = detector.oops();
188
189 int count = _oops_count;
190 for (int index = 0; index < _oops_count; index ++) {
191 assert(oops->contains(_oops[index]), "Must contain this oop");
192 }
193
194 for (oop* p = nm()->oops_begin(); p < nm()->oops_end(); p ++) {
195 if (*p == Universe::non_oop_word()) continue;
196 count++;
197 assert(oops->contains(p), "Must contain this oop");
198 }
199
200 if (oops->length() < count) {
201 stringStream debug_stream;
202 debug_stream.print_cr("detected locs: %d", oops->length());
203 for (int i = 0; i < oops->length(); i++) {
204 debug_stream.print_cr("-> " PTR_FORMAT, p2i(oops->at(i)));
205 }
206 debug_stream.print_cr("recorded oops: %d", _oops_count);
207 for (int i = 0; i < _oops_count; i++) {
208 debug_stream.print_cr("-> " PTR_FORMAT, p2i(_oops[i]));
209 }
210 GrowableArray<oop*> check;
211 bool non_immed;
212 detect_reloc_oops(nm(), check, non_immed);
213 debug_stream.print_cr("check oops: %d", check.length());
214 for (int i = 0; i < check.length(); i++) {
215 debug_stream.print_cr("-> " PTR_FORMAT, p2i(check.at(i)));
216 }
217 fatal("Must match #detected: %d, #recorded: %d, #total: %d, begin: " PTR_FORMAT ", end: " PTR_FORMAT "\n%s",
218 oops->length(), _oops_count, count, p2i(nm()->oops_begin()), p2i(nm()->oops_end()), debug_stream.freeze());
219 }
220 }
221 #endif
222
223 ShenandoahNMethodTable::ShenandoahNMethodTable() :
224 _heap(ShenandoahHeap::heap()),
225 _index(0),
226 _itr_cnt(0) {
227 _list = new ShenandoahNMethodList(minSize);
228 }
229
230 ShenandoahNMethodTable::~ShenandoahNMethodTable() {
231 assert(_list != nullptr, "Sanity");
232 _list->release();
233 }
234
235 void ShenandoahNMethodTable::register_nmethod(nmethod* nm) {
236 assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
237 assert(_index >= 0 && _index <= _list->size(), "Sanity");
238
239 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
240
241 if (data != nullptr) {
242 assert(contain(nm), "Must have been registered");
243 assert(nm == data->nm(), "Must be same nmethod");
244 // Prevent updating a nmethod while concurrent iteration is in progress.
245 wait_until_concurrent_iteration_done();
246 ShenandoahReentrantLocker data_locker(data->lock());
247 data->update();
248 } else {
249 // For a new nmethod, we can safely append it to the list, because
250 // concurrent iteration will not touch it.
251 data = ShenandoahNMethod::for_nmethod(nm);
252 assert(data != nullptr, "Sanity");
253 ShenandoahNMethod::attach_gc_data(nm, data);
254 ShenandoahLocker locker(&_lock);
255 log_register_nmethod(nm);
256 append(data);
257 }
258 // Disarm new nmethod
259 ShenandoahNMethod::disarm_nmethod(nm);
260 }
261
262 void ShenandoahNMethodTable::unregister_nmethod(nmethod* nm) {
263 assert_locked_or_safepoint(CodeCache_lock);
264
265 ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
266 assert(data != nullptr, "Sanity");
267 log_unregister_nmethod(nm);
268 ShenandoahLocker locker(&_lock);
269 assert(contain(nm), "Must have been registered");
270
271 int idx = index_of(nm);
272 assert(idx >= 0 && idx < _index, "Invalid index");
273 ShenandoahNMethod::attach_gc_data(nm, nullptr);
274 remove(idx);
275 }
276
277 bool ShenandoahNMethodTable::contain(nmethod* nm) const {
278 return index_of(nm) != -1;
279 }
280
281 ShenandoahNMethod* ShenandoahNMethodTable::at(int index) const {
282 assert(index >= 0 && index < _index, "Out of bound");
283 return _list->at(index);
284 }
285
286 int ShenandoahNMethodTable::index_of(nmethod* nm) const {
287 for (int index = 0; index < length(); index ++) {
288 if (at(index)->nm() == nm) {
289 return index;
290 }
291 }
292 return -1;
293 }
294
295 void ShenandoahNMethodTable::remove(int idx) {
296 shenandoah_assert_locked_or_safepoint(CodeCache_lock);
297 assert(_index >= 0 && _index <= _list->size(), "Sanity");
298
299 assert(idx >= 0 && idx < _index, "Out of bound");
300 ShenandoahNMethod* snm = _list->at(idx);
301 ShenandoahNMethod* tmp = _list->at(_index - 1);
302 _list->set(idx, tmp);
303 _index --;
304
305 delete snm;
306 }
307
308 void ShenandoahNMethodTable::wait_until_concurrent_iteration_done() {
309 assert(CodeCache_lock->owned_by_self(), "Lock must be held");
310 while (iteration_in_progress()) {
311 CodeCache_lock->wait_without_safepoint_check();
312 }
313 }
314
315 void ShenandoahNMethodTable::append(ShenandoahNMethod* snm) {
316 if (is_full()) {
317 int new_size = 2 * _list->size();
318 // Rebuild table and replace current one
319 rebuild(new_size);
320 }
321
322 _list->set(_index++, snm);
323 assert(_index >= 0 && _index <= _list->size(), "Sanity");
324 }
325
326 void ShenandoahNMethodTable::rebuild(int size) {
327 ShenandoahNMethodList* new_list = new ShenandoahNMethodList(size);
328 new_list->transfer(_list, _index);
329
330 // Release old list
331 _list->release();
332 _list = new_list;
333 }
334
335 ShenandoahNMethodTableSnapshot* ShenandoahNMethodTable::snapshot_for_iteration() {
336 assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
337 _itr_cnt++;
338 return new ShenandoahNMethodTableSnapshot(this);
339 }
340
341 void ShenandoahNMethodTable::finish_iteration(ShenandoahNMethodTableSnapshot* snapshot) {
342 assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
343 assert(iteration_in_progress(), "Why we here?");
344 assert(snapshot != nullptr, "No snapshot");
345 _itr_cnt--;
346
347 delete snapshot;
348 }
349
350 void ShenandoahNMethodTable::log_register_nmethod(nmethod* nm) {
351 LogTarget(Debug, gc, nmethod) log;
352 if (!log.is_enabled()) {
353 return;
354 }
355
356 ResourceMark rm;
357 log.print("Register NMethod: %s.%s [" PTR_FORMAT "] (%s)",
358 nm->method()->method_holder()->external_name(),
359 nm->method()->name()->as_C_string(),
360 p2i(nm),
361 nm->compiler_name());
362 }
363
364 void ShenandoahNMethodTable::log_unregister_nmethod(nmethod* nm) {
365 LogTarget(Debug, gc, nmethod) log;
366 if (!log.is_enabled()) {
367 return;
368 }
369
370 ResourceMark rm;
371 log.print("Unregister NMethod: %s.%s [" PTR_FORMAT "]",
372 nm->method()->method_holder()->external_name(),
373 nm->method()->name()->as_C_string(),
374 p2i(nm));
375 }
376
377 #ifdef ASSERT
378 void ShenandoahNMethodTable::assert_nmethods_correct() {
379 assert_locked_or_safepoint(CodeCache_lock);
380
381 for (int index = 0; index < length(); index ++) {
382 ShenandoahNMethod* m = _list->at(index);
383 // Concurrent unloading may have dead nmethods to be cleaned by sweeper
384 if (m->is_unregistered()) continue;
385 m->assert_correct();
386 }
387 }
388 #endif
389
390
391 ShenandoahNMethodList::ShenandoahNMethodList(int size) :
392 _size(size), _ref_count(1) {
393 _list = NEW_C_HEAP_ARRAY(ShenandoahNMethod*, size, mtGC);
394 }
395
396 ShenandoahNMethodList::~ShenandoahNMethodList() {
397 assert(_list != nullptr, "Sanity");
398 assert(_ref_count == 0, "Must be");
399 FREE_C_HEAP_ARRAY(ShenandoahNMethod*, _list);
400 }
401
402 void ShenandoahNMethodList::transfer(ShenandoahNMethodList* const list, int limit) {
403 assert(limit <= size(), "Sanity");
404 ShenandoahNMethod** old_list = list->list();
405 for (int index = 0; index < limit; index++) {
406 _list[index] = old_list[index];
407 }
408 }
409
410 ShenandoahNMethodList* ShenandoahNMethodList::acquire() {
411 assert_locked_or_safepoint(CodeCache_lock);
412 _ref_count++;
413 return this;
414 }
415
416 void ShenandoahNMethodList::release() {
417 assert_locked_or_safepoint(CodeCache_lock);
418 _ref_count--;
419 if (_ref_count == 0) {
420 delete this;
421 }
422 }
423
424 ShenandoahNMethodTableSnapshot::ShenandoahNMethodTableSnapshot(ShenandoahNMethodTable* table) :
425 _heap(ShenandoahHeap::heap()), _list(table->_list->acquire()), _limit(table->_index), _claimed(0) {
426 }
427
428 ShenandoahNMethodTableSnapshot::~ShenandoahNMethodTableSnapshot() {
429 _list->release();
430 }
431
432 void ShenandoahNMethodTableSnapshot::parallel_blobs_do(CodeBlobClosure *f) {
433 size_t stride = 256; // educated guess
434
435 ShenandoahNMethod** const list = _list->list();
436
437 size_t max = (size_t)_limit;
438 while (_claimed < max) {
439 size_t cur = Atomic::fetch_then_add(&_claimed, stride, memory_order_relaxed);
440 size_t start = cur;
441 size_t end = MIN2(cur + stride, max);
442 if (start >= max) break;
443
444 for (size_t idx = start; idx < end; idx++) {
445 ShenandoahNMethod* nmr = list[idx];
446 assert(nmr != nullptr, "Sanity");
447 if (nmr->is_unregistered()) {
448 continue;
449 }
450
451 nmr->assert_correct();
452 f->do_code_blob(nmr->nm());
453 }
454 }
455 }
456
457 void ShenandoahNMethodTableSnapshot::concurrent_nmethods_do(NMethodClosure* cl) {
458 size_t stride = 256; // educated guess
459
460 ShenandoahNMethod** list = _list->list();
461 size_t max = (size_t)_limit;
462 while (_claimed < max) {
463 size_t cur = Atomic::fetch_then_add(&_claimed, stride, memory_order_relaxed);
464 size_t start = cur;
465 size_t end = MIN2(cur + stride, max);
466 if (start >= max) break;
467
468 for (size_t idx = start; idx < end; idx++) {
469 ShenandoahNMethod* data = list[idx];
470 assert(data != nullptr, "Should not be null");
471 if (!data->is_unregistered()) {
472 cl->do_nmethod(data->nm());
473 }
474 }
475 }
476 }
477
478 ShenandoahConcurrentNMethodIterator::ShenandoahConcurrentNMethodIterator(ShenandoahNMethodTable* table) :
479 _table(table),
480 _table_snapshot(nullptr),
481 _started_workers(0),
482 _finished_workers(0) {}
483
484 void ShenandoahConcurrentNMethodIterator::nmethods_do(NMethodClosure* cl) {
485 // Cannot safepoint when iteration is running, because this can cause deadlocks
486 // with other threads waiting on iteration to be over.
487 NoSafepointVerifier nsv;
488
489 MutexLocker ml(CodeCache_lock, Mutex::_no_safepoint_check_flag);
490
491 if (_finished_workers > 0) {
492 // Some threads have already finished. We are now in rampdown: we are now
493 // waiting for all currently recorded workers to finish. No new workers
494 // should start.
495 return;
496 }
497
498 // Record a new worker and initialize the snapshot if it is a first visitor.
499 if (_started_workers++ == 0) {
500 _table_snapshot = _table->snapshot_for_iteration();
501 }
502
503 // All set, relinquish the lock and go concurrent.
504 {
505 MutexUnlocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
506 _table_snapshot->concurrent_nmethods_do(cl);
507 }
508
509 // Record completion. Last worker shuts down the iterator and notifies any waiters.
510 uint count = ++_finished_workers;
511 if (count == _started_workers) {
512 _table->finish_iteration(_table_snapshot);
513 CodeCache_lock->notify_all();
514 }
515 }