1 /*
2 * Copyright (c) 1997, 2016, 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 #include "utilities/align.hpp"
32
33
34 // Implementation of StubQueue
35 //
36 // Standard wrap-around queue implementation; the queue dimensions
37 // are specified by the _queue_begin & _queue_end indices. The queue
38 // can be in two states (transparent to the outside):
39 //
40 // a) contiguous state: all queue entries in one block (or empty)
41 //
42 // Queue: |...|XXXXXXX|...............|
43 // ^0 ^begin ^end ^size = limit
44 // |_______|
45 // one block
46 //
47 // b) non-contiguous state: queue entries in two blocks
48 //
49 // Queue: |XXX|.......|XXXXXXX|.......|
50 // ^0 ^end ^begin ^limit ^size
51 // |___| |_______|
52 // 1st block 2nd block
53 //
54 // In the non-contiguous state, the wrap-around point is
55 // indicated via the _buffer_limit index since the last
56 // queue entry may not fill up the queue completely in
57 // which case we need to know where the 2nd block's end
58 // is to do the proper wrap-around. When removing the
59 // last entry of the 2nd block, _buffer_limit is reset
60 // to _buffer_size.
61 //
62 // CAUTION: DO NOT MESS WITH THIS CODE IF YOU CANNOT PROVE
63 // ITS CORRECTNESS! THIS CODE IS MORE SUBTLE THAN IT LOOKS!
64
65
66 StubQueue::StubQueue(StubInterface* stub_interface, int buffer_size,
67 Mutex* lock, const char* name) : _mutex(lock) {
68 intptr_t size = align_up(buffer_size, 2*BytesPerWord);
69 BufferBlob* blob = BufferBlob::create(name, size);
70 if( blob == NULL) {
71 vm_exit_out_of_memory(size, OOM_MALLOC_ERROR, "CodeCache: no room for %s", name);
72 }
73 _stub_interface = stub_interface;
74 _buffer_size = blob->content_size();
75 _buffer_limit = blob->content_size();
76 _stub_buffer = blob->content_begin();
77 _queue_begin = 0;
78 _queue_end = 0;
79 _number_of_stubs = 0;
80 register_queue(this);
81 }
82
83
84 StubQueue::~StubQueue() {
85 // Note: Currently StubQueues are never destroyed so nothing needs to be done here.
86 // If we want to implement the destructor, we need to release the BufferBlob
87 // allocated in the constructor (i.e., we need to keep it around or look it
88 // up via CodeCache::find_blob(...).
89 Unimplemented();
90 }
91
92
93 Stub* StubQueue::stub_containing(address pc) const {
94 if (contains(pc)) {
95 for (Stub* s = first(); s != NULL; s = next(s)) {
96 if (stub_contains(s, pc)) return s;
97 }
98 }
99 return NULL;
100 }
101
102
103 Stub* StubQueue::request_committed(int code_size) {
104 Stub* s = request(code_size);
105 CodeStrings strings;
106 if (s != NULL) commit(code_size, strings);
107 return s;
108 }
109
110
111 Stub* StubQueue::request(int requested_code_size) {
112 assert(requested_code_size > 0, "requested_code_size must be > 0");
113 if (_mutex != NULL) _mutex->lock();
114 Stub* s = current_stub();
115 int requested_size = align_up(stub_code_size_to_size(requested_code_size), CodeEntryAlignment);
116 if (requested_size <= available_space()) {
117 if (is_contiguous()) {
118 // Queue: |...|XXXXXXX|.............|
119 // ^0 ^begin ^end ^size = limit
120 assert(_buffer_limit == _buffer_size, "buffer must be fully usable");
121 if (_queue_end + requested_size <= _buffer_size) {
122 // code fits in at the end => nothing to do
123 CodeStrings strings;
124 stub_initialize(s, requested_size, strings);
125 return s;
126 } else {
127 // stub doesn't fit in at the queue end
128 // => reduce buffer limit & wrap around
129 assert(!is_empty(), "just checkin'");
130 _buffer_limit = _queue_end;
131 _queue_end = 0;
132 }
133 }
134 }
135 if (requested_size <= available_space()) {
136 assert(!is_contiguous(), "just checkin'");
137 assert(_buffer_limit <= _buffer_size, "queue invariant broken");
138 // Queue: |XXX|.......|XXXXXXX|.......|
139 // ^0 ^end ^begin ^limit ^size
140 s = current_stub();
141 CodeStrings strings;
142 stub_initialize(s, requested_size, strings);
143 return s;
144 }
145 // Not enough space left
146 if (_mutex != NULL) _mutex->unlock();
147 return NULL;
148 }
149
150
151 void StubQueue::commit(int committed_code_size, CodeStrings& strings) {
152 assert(committed_code_size > 0, "committed_code_size must be > 0");
153 int committed_size = align_up(stub_code_size_to_size(committed_code_size), CodeEntryAlignment);
154 Stub* s = current_stub();
155 assert(committed_size <= stub_size(s), "committed size must not exceed requested size");
156 stub_initialize(s, committed_size, strings);
157 _queue_end += committed_size;
158 _number_of_stubs++;
159 if (_mutex != NULL) _mutex->unlock();
160 debug_only(stub_verify(s);)
161 }
162
163
164 void StubQueue::remove_first() {
165 if (number_of_stubs() == 0) return;
166 Stub* s = first();
167 debug_only(stub_verify(s);)
168 stub_finalize(s);
169 _queue_begin += stub_size(s);
170 assert(_queue_begin <= _buffer_limit, "sanity check");
171 if (_queue_begin == _queue_end) {
172 // buffer empty
173 // => reset queue indices
174 _queue_begin = 0;
175 _queue_end = 0;
176 _buffer_limit = _buffer_size;
177 } else if (_queue_begin == _buffer_limit) {
178 // buffer limit reached
179 // => reset buffer limit & wrap around
180 _buffer_limit = _buffer_size;
181 _queue_begin = 0;
182 }
183 _number_of_stubs--;
184 }
185
186
187 void StubQueue::remove_first(int n) {
188 int i = MIN2(n, number_of_stubs());
189 while (i-- > 0) remove_first();
190 }
191
192
193 void StubQueue::remove_all(){
194 debug_only(verify();)
195 remove_first(number_of_stubs());
196 assert(number_of_stubs() == 0, "sanity check");
197 }
198
199
200 enum { StubQueueLimit = 10 }; // there are only a few in the world
201 static StubQueue* registered_stub_queues[StubQueueLimit];
202
203 void StubQueue::register_queue(StubQueue* sq) {
204 for (int i = 0; i < StubQueueLimit; i++) {
205 if (registered_stub_queues[i] == NULL) {
206 registered_stub_queues[i] = sq;
207 return;
208 }
209 }
210 ShouldNotReachHere();
211 }
212
213
214 void StubQueue::queues_do(void f(StubQueue* sq)) {
215 for (int i = 0; i < StubQueueLimit; i++) {
216 if (registered_stub_queues[i] != NULL) {
217 f(registered_stub_queues[i]);
218 }
219 }
220 }
221
222
223 void StubQueue::stubs_do(void f(Stub* s)) {
224 debug_only(verify();)
225 MutexLockerEx lock(_mutex);
226 for (Stub* s = first(); s != NULL; s = next(s)) f(s);
227 }
228
229
230 void StubQueue::verify() {
231 // verify only if initialized
232 if (_stub_buffer == NULL) return;
233 MutexLockerEx lock(_mutex);
234 // verify index boundaries
235 guarantee(0 <= _buffer_size, "buffer size must be positive");
236 guarantee(0 <= _buffer_limit && _buffer_limit <= _buffer_size , "_buffer_limit out of bounds");
237 guarantee(0 <= _queue_begin && _queue_begin < _buffer_limit, "_queue_begin out of bounds");
238 guarantee(0 <= _queue_end && _queue_end <= _buffer_limit, "_queue_end out of bounds");
239 // verify alignment
240 guarantee(_buffer_size % CodeEntryAlignment == 0, "_buffer_size not aligned");
241 guarantee(_buffer_limit % CodeEntryAlignment == 0, "_buffer_limit not aligned");
242 guarantee(_queue_begin % CodeEntryAlignment == 0, "_queue_begin not aligned");
243 guarantee(_queue_end % CodeEntryAlignment == 0, "_queue_end not aligned");
244 // verify buffer limit/size relationship
245 if (is_contiguous()) {
246 guarantee(_buffer_limit == _buffer_size, "_buffer_limit must equal _buffer_size");
247 }
248 // verify contents
249 int n = 0;
250 for (Stub* s = first(); s != NULL; s = next(s)) {
251 stub_verify(s);
252 n++;
253 }
254 guarantee(n == number_of_stubs(), "number of stubs inconsistent");
255 guarantee(_queue_begin != _queue_end || n == 0, "buffer indices must be the same");
256 }
257
258
259 void StubQueue::print() {
260 MutexLockerEx lock(_mutex);
261 for (Stub* s = first(); s != NULL; s = next(s)) {
262 stub_print(s);
263 }
264 }
265