1 /*
2 * Copyright (c) 2014, 2018, 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 "code/codeCache.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"
29 #include "gc_implementation/g1/heapRegion.hpp"
30 #include "memory/heap.hpp"
31 #include "memory/iterator.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "utilities/hashtable.inline.hpp"
34 #include "utilities/stack.inline.hpp"
35
36 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
37
38 class CodeRootSetTable : public Hashtable<nmethod*, mtGC> {
39 friend class G1CodeRootSetTest;
40 typedef HashtableEntry<nmethod*, mtGC> Entry;
41
42 static CodeRootSetTable* volatile _purge_list;
43
44 CodeRootSetTable* _purge_next;
45
46 unsigned int compute_hash(nmethod* nm) {
47 uintptr_t hash = (uintptr_t)nm;
48 return hash ^ (hash >> 7); // code heap blocks are 128byte aligned
49 }
50
51 void remove_entry(Entry* e, Entry* previous);
52 Entry* new_entry(nmethod* nm);
53
54 public:
55 CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {}
56 ~CodeRootSetTable();
57
58 // Needs to be protected locks
59 bool add(nmethod* nm);
60 bool remove(nmethod* nm);
61
62 // Can be called without locking
63 bool contains(nmethod* nm);
64
65 int entry_size() const { return BasicHashtable<mtGC>::entry_size(); }
66
67 void copy_to(CodeRootSetTable* new_table);
68 void nmethods_do(CodeBlobClosure* blk);
69
70 template<typename CB>
71 int remove_if(CB& should_remove);
72
73 static void purge_list_append(CodeRootSetTable* tbl);
74 static void purge();
75
76 static size_t static_mem_size() {
77 return sizeof(_purge_list);
78 }
79
80 size_t mem_size();
81 };
82
83 CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL;
84
85 size_t CodeRootSetTable::mem_size() {
86 return sizeof(CodeRootSetTable) + (entry_size() * number_of_entries()) + (sizeof(HashtableBucket<mtGC>) * table_size());
87 }
88
89 CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) {
90 unsigned int hash = compute_hash(nm);
91 Entry* entry = (Entry*) new_entry_free_list();
92 if (entry == NULL) {
93 entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC);
94 }
95 entry->set_next(NULL);
96 entry->set_hash(hash);
97 entry->set_literal(nm);
98 return entry;
99 }
100
101 void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) {
102 int index = hash_to_index(e->hash());
103 assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null");
104
105 if (previous == NULL) {
106 set_entry(index, e->next());
107 } else {
108 previous->set_next(e->next());
109 }
110 free_entry(e);
111 }
112
113 CodeRootSetTable::~CodeRootSetTable() {
114 for (int index = 0; index < table_size(); ++index) {
115 for (Entry* e = bucket(index); e != NULL; ) {
116 Entry* to_remove = e;
117 // read next before freeing.
118 e = e->next();
119 unlink_entry(to_remove);
120 FREE_C_HEAP_ARRAY(char, to_remove, mtGC);
121 }
122 }
123 assert(number_of_entries() == 0, "should have removed all entries");
124 free_buckets();
125 for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) {
126 FREE_C_HEAP_ARRAY(char, e, mtGC);
127 }
128 }
129
130 bool CodeRootSetTable::add(nmethod* nm) {
131 if (!contains(nm)) {
132 Entry* e = new_entry(nm);
133 int index = hash_to_index(e->hash());
134 add_entry(index, e);
135 return true;
136 }
137 return false;
138 }
139
140 bool CodeRootSetTable::contains(nmethod* nm) {
141 int index = hash_to_index(compute_hash(nm));
142 for (Entry* e = bucket(index); e != NULL; e = e->next()) {
143 if (e->literal() == nm) {
144 return true;
145 }
146 }
147 return false;
148 }
149
150 bool CodeRootSetTable::remove(nmethod* nm) {
151 int index = hash_to_index(compute_hash(nm));
152 Entry* previous = NULL;
153 for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) {
154 if (e->literal() == nm) {
155 remove_entry(e, previous);
156 return true;
157 }
158 }
159 return false;
160 }
161
162 void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) {
163 for (int index = 0; index < table_size(); ++index) {
164 for (Entry* e = bucket(index); e != NULL; e = e->next()) {
165 new_table->add(e->literal());
166 }
167 }
168 new_table->copy_freelist(this);
169 }
170
171 void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) {
172 for (int index = 0; index < table_size(); ++index) {
173 for (Entry* e = bucket(index); e != NULL; e = e->next()) {
174 blk->do_code_blob(e->literal());
175 }
176 }
177 }
178
179 template<typename CB>
180 int CodeRootSetTable::remove_if(CB& should_remove) {
181 int num_removed = 0;
182 for (int index = 0; index < table_size(); ++index) {
183 Entry* previous = NULL;
184 Entry* e = bucket(index);
185 while (e != NULL) {
186 Entry* next = e->next();
187 if (should_remove(e->literal())) {
188 remove_entry(e, previous);
189 ++num_removed;
190 } else {
191 previous = e;
192 }
193 e = next;
194 }
195 }
196 return num_removed;
197 }
198
199 G1CodeRootSet::~G1CodeRootSet() {
200 delete _table;
201 }
202
203 CodeRootSetTable* G1CodeRootSet::load_acquire_table() {
204 return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table);
205 }
206
207 void G1CodeRootSet::allocate_small_table() {
208 _table = new CodeRootSetTable(SmallSize);
209 }
210
211 void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) {
212 for (;;) {
213 table->_purge_next = _purge_list;
214 CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next);
215 if (old == table->_purge_next) {
216 break;
217 }
218 }
219 }
220
221 void CodeRootSetTable::purge() {
222 CodeRootSetTable* table = _purge_list;
223 _purge_list = NULL;
224 while (table != NULL) {
225 CodeRootSetTable* to_purge = table;
226 table = table->_purge_next;
227 delete to_purge;
228 }
229 }
230
231 void G1CodeRootSet::move_to_large() {
232 CodeRootSetTable* temp = new CodeRootSetTable(LargeSize);
233
234 _table->copy_to(temp);
235
236 CodeRootSetTable::purge_list_append(_table);
237
238 OrderAccess::release_store_ptr(&_table, temp);
239 }
240
241 void G1CodeRootSet::purge() {
242 CodeRootSetTable::purge();
243 }
244
245 size_t G1CodeRootSet::static_mem_size() {
246 return CodeRootSetTable::static_mem_size();
247 }
248
249 void G1CodeRootSet::add(nmethod* method) {
250 bool added = false;
251 if (is_empty()) {
252 allocate_small_table();
253 }
254 added = _table->add(method);
255 if (added) {
256 if (_length == Threshold) {
257 move_to_large();
258 }
259 ++_length;
260 }
261 assert(_length == (size_t)_table->number_of_entries(), "sizes should match");
262 }
263
264 bool G1CodeRootSet::remove(nmethod* method) {
265 bool removed = false;
266 if (_table != NULL) {
267 removed = _table->remove(method);
268 }
269 if (removed) {
270 _length--;
271 if (_length == 0) {
272 clear();
273 }
274 }
275 assert((_length == 0 && _table == NULL) ||
276 (_length == (size_t)_table->number_of_entries()), "sizes should match");
277 return removed;
278 }
279
280 bool G1CodeRootSet::contains(nmethod* method) {
281 CodeRootSetTable* table = load_acquire_table(); // contains() may be called outside of lock, so ensure mem sync.
282 if (table != NULL) {
283 return table->contains(method);
284 }
285 return false;
286 }
287
288 void G1CodeRootSet::clear() {
289 delete _table;
290 _table = NULL;
291 _length = 0;
292 }
293
294 size_t G1CodeRootSet::mem_size() {
295 return sizeof(*this) + (_table != NULL ? _table->mem_size() : 0);
296 }
297
298 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {
299 if (_table != NULL) {
300 _table->nmethods_do(blk);
301 }
302 }
303
304 class CleanCallback : public StackObj {
305 class PointsIntoHRDetectionClosure : public OopClosure {
306 HeapRegion* _hr;
307 public:
308 bool _points_into;
309 PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {}
310
311 void do_oop(narrowOop* o) {
312 do_oop_work(o);
313 }
314
315 void do_oop(oop* o) {
316 do_oop_work(o);
317 }
318
319 template <typename T>
320 void do_oop_work(T* p) {
321 if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) {
322 _points_into = true;
323 }
324 }
325 };
326
327 PointsIntoHRDetectionClosure _detector;
328 CodeBlobToOopClosure _blobs;
329
330 public:
331 CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {}
332
333 bool operator() (nmethod* nm) {
334 _detector._points_into = false;
335 _blobs.do_code_blob(nm);
336 return !_detector._points_into;
337 }
338 };
339
340 void G1CodeRootSet::clean(HeapRegion* owner) {
341 CleanCallback should_clean(owner);
342 if (_table != NULL) {
343 int removed = _table->remove_if(should_clean);
344 assert((size_t)removed <= _length, "impossible");
345 _length -= removed;
346 }
347 if (_length == 0) {
348 clear();
349 }
350 }
351
352 #ifndef PRODUCT
353
354 class G1CodeRootSetTest {
355 public:
356 static void test() {
357 {
358 G1CodeRootSet set1;
359 assert(set1.is_empty(), "Code root set must be initially empty but is not.");
360
361 assert(G1CodeRootSet::static_mem_size() == sizeof(void*),
362 err_msg("The code root set's static memory usage is incorrect, " SIZE_FORMAT " bytes", G1CodeRootSet::static_mem_size()));
363
364 set1.add((nmethod*)1);
365 assert(set1.length() == 1, err_msg("Added exactly one element, but set contains "
366 SIZE_FORMAT " elements", set1.length()));
367
368 const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1;
369
370 for (size_t i = 1; i <= num_to_add; i++) {
371 set1.add((nmethod*)1);
372 }
373 assert(set1.length() == 1,
374 err_msg("Duplicate detection should not have increased the set size but "
375 "is " SIZE_FORMAT, set1.length()));
376
377 for (size_t i = 2; i <= num_to_add; i++) {
378 set1.add((nmethod*)(uintptr_t)(i));
379 }
380 assert(set1.length() == num_to_add,
381 err_msg("After adding in total " SIZE_FORMAT " distinct code roots, they "
382 "need to be in the set, but there are only " SIZE_FORMAT,
383 num_to_add, set1.length()));
384
385 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
386
387 size_t num_popped = 0;
388 for (size_t i = 1; i <= num_to_add; i++) {
389 bool removed = set1.remove((nmethod*)i);
390 if (removed) {
391 num_popped += 1;
392 } else {
393 break;
394 }
395 }
396 assert(num_popped == num_to_add,
397 err_msg("Managed to pop " SIZE_FORMAT " code roots, but only " SIZE_FORMAT " "
398 "were added", num_popped, num_to_add));
399 assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
400
401 G1CodeRootSet::purge();
402
403 assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables");
404
405 }
406
407 }
408 };
409
410 void TestCodeCacheRemSet_test() {
411 G1CodeRootSetTest::test();
412 }
413
414 #endif