1 /*
2 * Copyright (c) 1997, 2010, 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/codeBlob.hpp"
27 #include "code/stubs.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "runtime/mutexLocker.hpp"
31
32
33 // Implementation of StubQueue
34 //
35 // Standard wrap-around queue implementation; the queue dimensions
36 // are specified by the _queue_begin & _queue_end indices. The queue
37 // can be in two states (transparent to the outside):
38 //
39 // a) contiguous state: all queue entries in one block (or empty)
40 //
41 // Queue: |...|XXXXXXX|...............|
42 // ^0 ^begin ^end ^size = limit
43 // |_______|
44 // one block
45 //
46 // b) non-contiguous state: queue entries in two blocks
47 //
48 // Queue: |XXX|.......|XXXXXXX|.......|
49 // ^0 ^end ^begin ^limit ^size
50 // |___| |_______|
51 // 1st block 2nd block
52 //
53 // In the non-contiguous state, the wrap-around point is
54 // indicated via the _buffer_limit index since the last
55 // queue entry may not fill up the queue completely in
56 // which case we need to know where the 2nd block's end
57 // is to do the proper wrap-around. When removing the
58 // last entry of the 2nd block, _buffer_limit is reset
59 // to _buffer_size.
60 //
61 // CAUTION: DO NOT MESS WITH THIS CODE IF YOU CANNOT PROVE
62 // ITS CORRECTNESS! THIS CODE IS MORE SUBTLE THAN IT LOOKS!
63
64
65 StubQueue::StubQueue(StubInterface* stub_interface, int buffer_size,
66 Mutex* lock, const char* name) : _mutex(lock) {
67 intptr_t size = round_to(buffer_size, 2*BytesPerWord);
68 BufferBlob* blob = BufferBlob::create(name, size);
69 if( blob == NULL) {
70 vm_exit_out_of_memory(size, err_msg("CodeCache: no room for %s", name));
71 }
72 _stub_interface = stub_interface;
73 _buffer_size = blob->content_size();
74 _buffer_limit = blob->content_size();
75 _stub_buffer = blob->content_begin();
76 _queue_begin = 0;
77 _queue_end = 0;
78 _number_of_stubs = 0;
79 register_queue(this);
80 }
81
82
83 StubQueue::~StubQueue() {
84 // Note: Currently StubQueues are never destroyed so nothing needs to be done here.
85 // If we want to implement the destructor, we need to release the BufferBlob
86 // allocated in the constructor (i.e., we need to keep it around or look it
87 // up via CodeCache::find_blob(...).
88 Unimplemented();
89 }
90
91
92 Stub* StubQueue::stub_containing(address pc) const {
93 if (contains(pc)) {
94 for (Stub* s = first(); s != NULL; s = next(s)) {
95 if (stub_contains(s, pc)) return s;
96 }
97 }
98 return NULL;
99 }
100
101
102 Stub* StubQueue::request_committed(int code_size) {
103 Stub* s = request(code_size);
104 if (s != NULL) commit(code_size);
105 return s;
106 }
107
108
109 Stub* StubQueue::request(int requested_code_size) {
110 assert(requested_code_size > 0, "requested_code_size must be > 0");
111 if (_mutex != NULL) _mutex->lock();
112 Stub* s = current_stub();
113 int requested_size = round_to(stub_code_size_to_size(requested_code_size), CodeEntryAlignment);
114 if (requested_size <= available_space()) {
115 if (is_contiguous()) {
116 // Queue: |...|XXXXXXX|.............|
117 // ^0 ^begin ^end ^size = limit
118 assert(_buffer_limit == _buffer_size, "buffer must be fully usable");
119 if (_queue_end + requested_size <= _buffer_size) {
120 // code fits in at the end => nothing to do
121 stub_initialize(s, requested_size);
122 return s;
123 } else {
124 // stub doesn't fit in at the queue end
125 // => reduce buffer limit & wrap around
126 assert(!is_empty(), "just checkin'");
127 _buffer_limit = _queue_end;
128 _queue_end = 0;
129 }
130 }
131 }
132 if (requested_size <= available_space()) {
133 assert(!is_contiguous(), "just checkin'");
134 assert(_buffer_limit <= _buffer_size, "queue invariant broken");
135 // Queue: |XXX|.......|XXXXXXX|.......|
136 // ^0 ^end ^begin ^limit ^size
137 s = current_stub();
138 stub_initialize(s, requested_size);
139 return s;
140 }
141 // Not enough space left
142 if (_mutex != NULL) _mutex->unlock();
143 return NULL;
144 }
145
146
147 void StubQueue::commit(int committed_code_size) {
148 assert(committed_code_size > 0, "committed_code_size must be > 0");
149 int committed_size = round_to(stub_code_size_to_size(committed_code_size), CodeEntryAlignment);
150 Stub* s = current_stub();
151 assert(committed_size <= stub_size(s), "committed size must not exceed requested size");
152 stub_initialize(s, committed_size);
153 _queue_end += committed_size;
154 _number_of_stubs++;
155 if (_mutex != NULL) _mutex->unlock();
156 debug_only(stub_verify(s);)
157 }
158
159
160 void StubQueue::remove_first() {
161 if (number_of_stubs() == 0) return;
162 Stub* s = first();
163 debug_only(stub_verify(s);)
164 stub_finalize(s);
165 _queue_begin += stub_size(s);
166 assert(_queue_begin <= _buffer_limit, "sanity check");
167 if (_queue_begin == _queue_end) {
168 // buffer empty
169 // => reset queue indices
170 _queue_begin = 0;
171 _queue_end = 0;
172 _buffer_limit = _buffer_size;
173 } else if (_queue_begin == _buffer_limit) {
174 // buffer limit reached
175 // => reset buffer limit & wrap around
176 _buffer_limit = _buffer_size;
177 _queue_begin = 0;
178 }
179 _number_of_stubs--;
180 }
181
182
183 void StubQueue::remove_first(int n) {
184 int i = MIN2(n, number_of_stubs());
185 while (i-- > 0) remove_first();
186 }
187
188
189 void StubQueue::remove_all(){
190 debug_only(verify();)
191 remove_first(number_of_stubs());
192 assert(number_of_stubs() == 0, "sanity check");
193 }
194
195
196 enum { StubQueueLimit = 10 }; // there are only a few in the world
197 static StubQueue* registered_stub_queues[StubQueueLimit];
198
199 void StubQueue::register_queue(StubQueue* sq) {
200 for (int i = 0; i < StubQueueLimit; i++) {
201 if (registered_stub_queues[i] == NULL) {
202 registered_stub_queues[i] = sq;
203 return;
204 }
205 }
206 ShouldNotReachHere();
207 }
208
209
210 void StubQueue::queues_do(void f(StubQueue* sq)) {
211 for (int i = 0; i < StubQueueLimit; i++) {
212 if (registered_stub_queues[i] != NULL) {
213 f(registered_stub_queues[i]);
214 }
215 }
216 }
217
218
219 void StubQueue::stubs_do(void f(Stub* s)) {
220 debug_only(verify();)
221 MutexLockerEx lock(_mutex);
222 for (Stub* s = first(); s != NULL; s = next(s)) f(s);
223 }
224
225
226 void StubQueue::verify() {
227 // verify only if initialized
228 if (_stub_buffer == NULL) return;
229 MutexLockerEx lock(_mutex);
230 // verify index boundaries
231 guarantee(0 <= _buffer_size, "buffer size must be positive");
232 guarantee(0 <= _buffer_limit && _buffer_limit <= _buffer_size , "_buffer_limit out of bounds");
233 guarantee(0 <= _queue_begin && _queue_begin < _buffer_limit, "_queue_begin out of bounds");
234 guarantee(0 <= _queue_end && _queue_end <= _buffer_limit, "_queue_end out of bounds");
235 // verify alignment
236 guarantee(_buffer_size % CodeEntryAlignment == 0, "_buffer_size not aligned");
237 guarantee(_buffer_limit % CodeEntryAlignment == 0, "_buffer_limit not aligned");
238 guarantee(_queue_begin % CodeEntryAlignment == 0, "_queue_begin not aligned");
239 guarantee(_queue_end % CodeEntryAlignment == 0, "_queue_end not aligned");
240 // verify buffer limit/size relationship
241 if (is_contiguous()) {
242 guarantee(_buffer_limit == _buffer_size, "_buffer_limit must equal _buffer_size");
243 }
244 // verify contents
245 int n = 0;
246 for (Stub* s = first(); s != NULL; s = next(s)) {
247 stub_verify(s);
248 n++;
249 }
250 guarantee(n == number_of_stubs(), "number of stubs inconsistent");
251 guarantee(_queue_begin != _queue_end || n == 0, "buffer indices must be the same");
252 }
253
254
255 void StubQueue::print() {
256 MutexLockerEx lock(_mutex);
257 for (Stub* s = first(); s != NULL; s = next(s)) {
258 stub_print(s);
259 }
260 }