1 /*
2 * Copyright (c) 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
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc/shared/scavengableNMethods.hpp"
29 #include "gc/shared/scavengableNMethodsData.hpp"
30 #include "runtime/mutexLocker.hpp"
31 #include "utilities/debug.hpp"
32
gc_data(nmethod * nm)33 static ScavengableNMethodsData gc_data(nmethod* nm) {
34 return ScavengableNMethodsData(nm);
35 }
36
37 nmethod* ScavengableNMethods::_head = NULL;
38 BoolObjectClosure* ScavengableNMethods::_is_scavengable = NULL;
39
initialize(BoolObjectClosure * is_scavengable)40 void ScavengableNMethods::initialize(BoolObjectClosure* is_scavengable) {
41 _is_scavengable = is_scavengable;
42 }
43
44 // Conditionally adds the nmethod to the list if it is
45 // not already on the list and has a scavengeable root.
register_nmethod(nmethod * nm)46 void ScavengableNMethods::register_nmethod(nmethod* nm) {
47 assert_locked_or_safepoint(CodeCache_lock);
48
49 ScavengableNMethodsData data = gc_data(nm);
50
51 if (data.on_list() || !has_scavengable_oops(nm)) {
52 return;
53 }
54
55 data.set_on_list();
56 data.set_next(_head);
57
58 _head = nm;
59 }
60
unregister_nmethod(nmethod * nm)61 void ScavengableNMethods::unregister_nmethod(nmethod* nm) {
62 assert_locked_or_safepoint(CodeCache_lock);
63
64 if (gc_data(nm).on_list()) {
65 nmethod* prev = NULL;
66 for (nmethod* cur = _head; cur != NULL; cur = gc_data(cur).next()) {
67 if (cur == nm) {
68 unlist_nmethod(cur, prev);
69 return;
70 }
71 prev = cur;
72 }
73 }
74 }
75
76 #ifndef PRODUCT
77
78 class DebugScavengableOops: public OopClosure {
79 BoolObjectClosure* _is_scavengable;
80 nmethod* _nm;
81 bool _ok;
82 public:
DebugScavengableOops(BoolObjectClosure * is_scavengable,nmethod * nm)83 DebugScavengableOops(BoolObjectClosure* is_scavengable, nmethod* nm) :
84 _is_scavengable(is_scavengable),
85 _nm(nm),
86 _ok(true) { }
87
ok()88 bool ok() { return _ok; }
do_oop(oop * p)89 virtual void do_oop(oop* p) {
90 if (*p == NULL || !_is_scavengable->do_object_b(*p)) {
91 return;
92 }
93
94 if (_ok) {
95 _nm->print_nmethod(true);
96 _ok = false;
97 }
98 tty->print_cr("*** scavengable oop " PTR_FORMAT " found at " PTR_FORMAT " (offset %d)",
99 p2i(*p), p2i(p), (int)((intptr_t)p - (intptr_t)_nm));
100 (*p)->print();
101 }
do_oop(narrowOop * p)102 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
103 };
104
105 #endif // PRODUCT
106
verify_nmethod(nmethod * nm)107 void ScavengableNMethods::verify_nmethod(nmethod* nm) {
108 #ifndef PRODUCT
109 if (!gc_data(nm).on_list()) {
110 // Actually look inside, to verify the claim that it's clean.
111 DebugScavengableOops cl(_is_scavengable, nm);
112 nm->oops_do(&cl);
113 if (!cl.ok())
114 fatal("found an unadvertised bad scavengable oop in the code cache");
115 }
116 assert(gc_data(nm).not_marked(), "");
117 #endif // PRODUCT
118 }
119
120 class HasScavengableOops: public OopClosure {
121 BoolObjectClosure* _is_scavengable;
122 bool _found;
123 public:
HasScavengableOops(BoolObjectClosure * is_scavengable,nmethod * nm)124 HasScavengableOops(BoolObjectClosure* is_scavengable, nmethod* nm) :
125 _is_scavengable(is_scavengable),
126 _found(false) {}
127
found()128 bool found() { return _found; }
do_oop(oop * p)129 virtual void do_oop(oop* p) {
130 if (!_found && *p != NULL && _is_scavengable->do_object_b(*p)) {
131 _found = true;
132 }
133 }
do_oop(narrowOop * p)134 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
135 };
136
has_scavengable_oops(nmethod * nm)137 bool ScavengableNMethods::has_scavengable_oops(nmethod* nm) {
138 HasScavengableOops cl(_is_scavengable, nm);
139 nm->oops_do(&cl);
140 return cl.found();
141 }
142
143 // Walk the list of methods which might contain oops to the java heap.
nmethods_do_and_prune(CodeBlobToOopClosure * cl)144 void ScavengableNMethods::nmethods_do_and_prune(CodeBlobToOopClosure* cl) {
145 assert_locked_or_safepoint(CodeCache_lock);
146
147 debug_only(mark_on_list_nmethods());
148
149 nmethod* prev = NULL;
150 nmethod* cur = _head;
151 while (cur != NULL) {
152 assert(cur->is_alive(), "Must be");
153
154 ScavengableNMethodsData data = gc_data(cur);
155 debug_only(data.clear_marked());
156 assert(data.on_list(), "else shouldn't be on this list");
157
158 if (cl != NULL) {
159 cl->do_code_blob(cur);
160 }
161
162 nmethod* const next = data.next();
163
164 if (!has_scavengable_oops(cur)) {
165 unlist_nmethod(cur, prev);
166 } else {
167 prev = cur;
168 }
169
170 cur = next;
171 }
172
173 // Check for stray marks.
174 debug_only(verify_unlisted_nmethods(NULL));
175 }
176
prune_nmethods()177 void ScavengableNMethods::prune_nmethods() {
178 nmethods_do_and_prune(NULL /* No closure */);
179 }
180
181 // Walk the list of methods which might contain oops to the java heap.
nmethods_do(CodeBlobToOopClosure * cl)182 void ScavengableNMethods::nmethods_do(CodeBlobToOopClosure* cl) {
183 nmethods_do_and_prune(cl);
184 }
185
186 #ifndef PRODUCT
asserted_non_scavengable_nmethods_do(CodeBlobClosure * cl)187 void ScavengableNMethods::asserted_non_scavengable_nmethods_do(CodeBlobClosure* cl) {
188 // While we are here, verify the integrity of the list.
189 mark_on_list_nmethods();
190 for (nmethod* cur = _head; cur != NULL; cur = gc_data(cur).next()) {
191 assert(gc_data(cur).on_list(), "else shouldn't be on this list");
192 gc_data(cur).clear_marked();
193 }
194 verify_unlisted_nmethods(cl);
195 }
196 #endif // PRODUCT
197
unlist_nmethod(nmethod * nm,nmethod * prev)198 void ScavengableNMethods::unlist_nmethod(nmethod* nm, nmethod* prev) {
199 assert_locked_or_safepoint(CodeCache_lock);
200
201 assert((prev == NULL && _head == nm) ||
202 (prev != NULL && gc_data(prev).next() == nm), "precondition");
203
204 ScavengableNMethodsData data = gc_data(nm);
205
206 if (prev == NULL) {
207 _head = data.next();
208 } else {
209 gc_data(prev).set_next(data.next());
210 }
211 data.set_next(NULL);
212 data.clear_on_list();
213 }
214
215 #ifndef PRODUCT
216 // Temporarily mark nmethods that are claimed to be on the scavenge list.
mark_on_list_nmethods()217 void ScavengableNMethods::mark_on_list_nmethods() {
218 NMethodIterator iter(NMethodIterator::only_alive);
219 while(iter.next()) {
220 nmethod* nm = iter.method();
221 ScavengableNMethodsData data = gc_data(nm);
222 assert(data.not_marked(), "clean state");
223 if (data.on_list())
224 data.set_marked();
225 }
226 }
227
228 // If the closure is given, run it on the unlisted nmethods.
229 // Also make sure that the effects of mark_on_list_nmethods is gone.
verify_unlisted_nmethods(CodeBlobClosure * cl)230 void ScavengableNMethods::verify_unlisted_nmethods(CodeBlobClosure* cl) {
231 NMethodIterator iter(NMethodIterator::only_alive);
232 while(iter.next()) {
233 nmethod* nm = iter.method();
234
235 verify_nmethod(nm);
236
237 if (cl != NULL && !gc_data(nm).on_list()) {
238 cl->do_code_blob(nm);
239 }
240 }
241 }
242
243 #endif //PRODUCT
244