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/codeCache.hpp"
28 #include "code/stubs.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/mutexLocker.hpp"
32 #include "utilities/align.hpp"
33
34
35 // Implementation of StubQueue
36 //
37 // Standard wrap-around queue implementation; the queue dimensions
38 // are specified by the _queue_begin & _queue_end indices. The queue
39 // can be in two states (transparent to the outside):
40 //
41 // a) contiguous state: all queue entries in one block (or empty)
42 //
43 // Queue: |...|XXXXXXX|...............|
44 // ^0 ^begin ^end ^size = limit
45 // |_______|
46 // one block
47 //
48 // b) non-contiguous state: queue entries in two blocks
49 //
50 // Queue: |XXX|.......|XXXXXXX|.......|
51 // ^0 ^end ^begin ^limit ^size
52 // |___| |_______|
53 // 1st block 2nd block
54 //
55 // In the non-contiguous state, the wrap-around point is
56 // indicated via the _buffer_limit index since the last
57 // queue entry may not fill up the queue completely in
58 // which case we need to know where the 2nd block's end
59 // is to do the proper wrap-around. When removing the
60 // last entry of the 2nd block, _buffer_limit is reset
61 // to _buffer_size.
62 //
63 // CAUTION: DO NOT MESS WITH THIS CODE IF YOU CANNOT PROVE
64 // ITS CORRECTNESS! THIS CODE IS MORE SUBTLE THAN IT LOOKS!
65
66
67 StubQueue::StubQueue(StubInterface* stub_interface, int buffer_size,
68 Mutex* lock, const char* name) : _mutex(lock) {
69 intptr_t size = align_up(buffer_size, 2*BytesPerWord);
70 BufferBlob* blob = BufferBlob::create(name, size);
71 if( blob == NULL) {
72 vm_exit_out_of_memory(size, OOM_MALLOC_ERROR, "CodeCache: no room for %s", name);
73 }
74 _stub_interface = stub_interface;
75 _buffer_size = blob->content_size();
76 _buffer_limit = blob->content_size();
77 _stub_buffer = blob->content_begin();
78 _queue_begin = 0;
79 _queue_end = 0;
80 _number_of_stubs = 0;
81 register_queue(this);
82 }
83
84
85 StubQueue::~StubQueue() {
86 // Note: Currently StubQueues are never destroyed so nothing needs to be done here.
87 // If we want to implement the destructor, we need to release the BufferBlob
88 // allocated in the constructor (i.e., we need to keep it around or look it
89 // up via CodeCache::find_blob(...).
90 Unimplemented();
91 }
92
93 void StubQueue::deallocate_unused_tail() {
94 CodeBlob* blob = CodeCache::find_blob((void*)_stub_buffer);
95 CodeCache::free_unused_tail(blob, used_space());
96 // Update the limits to the new, trimmed CodeBlob size
97 _buffer_size = blob->content_size();
98 _buffer_limit = blob->content_size();
99 }
100
101 Stub* StubQueue::stub_containing(address pc) const {
102 if (contains(pc)) {
103 for (Stub* s = first(); s != NULL; s = next(s)) {
104 if (stub_contains(s, pc)) return s;
105 }
106 }
107 return NULL;
108 }
109
110
111 Stub* StubQueue::request_committed(int code_size) {
112 Stub* s = request(code_size);
113 CodeStrings strings;
114 if (s != NULL) commit(code_size, strings);
115 return s;
116 }
117
118
119 Stub* StubQueue::request(int requested_code_size) {
120 assert(requested_code_size > 0, "requested_code_size must be > 0");
121 if (_mutex != NULL) _mutex->lock();
122 Stub* s = current_stub();
123 int requested_size = align_up(stub_code_size_to_size(requested_code_size), CodeEntryAlignment);
124 if (requested_size <= available_space()) {
125 if (is_contiguous()) {
126 // Queue: |...|XXXXXXX|.............|
127 // ^0 ^begin ^end ^size = limit
128 assert(_buffer_limit == _buffer_size, "buffer must be fully usable");
129 if (_queue_end + requested_size <= _buffer_size) {
130 // code fits in at the end => nothing to do
131 CodeStrings strings;
132 stub_initialize(s, requested_size, strings);
133 return s;
134 } else {
135 // stub doesn't fit in at the queue end
136 // => reduce buffer limit & wrap around
137 assert(!is_empty(), "just checkin'");
138 _buffer_limit = _queue_end;
139 _queue_end = 0;
140 }
141 }
142 }
143 if (requested_size <= available_space()) {
144 assert(!is_contiguous(), "just checkin'");
145 assert(_buffer_limit <= _buffer_size, "queue invariant broken");
146 // Queue: |XXX|.......|XXXXXXX|.......|
147 // ^0 ^end ^begin ^limit ^size
148 s = current_stub();
149 CodeStrings strings;
150 stub_initialize(s, requested_size, strings);
151 return s;
152 }
153 // Not enough space left
154 if (_mutex != NULL) _mutex->unlock();
155 return NULL;
156 }
157
158
159 void StubQueue::commit(int committed_code_size, CodeStrings& strings) {
160 assert(committed_code_size > 0, "committed_code_size must be > 0");
161 int committed_size = align_up(stub_code_size_to_size(committed_code_size), CodeEntryAlignment);
162 Stub* s = current_stub();
163 assert(committed_size <= stub_size(s), "committed size must not exceed requested size");
164 stub_initialize(s, committed_size, strings);
165 _queue_end += committed_size;
166 _number_of_stubs++;
167 if (_mutex != NULL) _mutex->unlock();
168 debug_only(stub_verify(s);)
169 }
170
171
172 void StubQueue::remove_first() {
173 if (number_of_stubs() == 0) return;
174 Stub* s = first();
175 debug_only(stub_verify(s);)
176 stub_finalize(s);
177 _queue_begin += stub_size(s);
178 assert(_queue_begin <= _buffer_limit, "sanity check");
179 if (_queue_begin == _queue_end) {
180 // buffer empty
181 // => reset queue indices
182 _queue_begin = 0;
183 _queue_end = 0;
184 _buffer_limit = _buffer_size;
185 } else if (_queue_begin == _buffer_limit) {
186 // buffer limit reached
187 // => reset buffer limit & wrap around
188 _buffer_limit = _buffer_size;
189 _queue_begin = 0;
190 }
191 _number_of_stubs--;
192 }
193
194
195 void StubQueue::remove_first(int n) {
196 int i = MIN2(n, number_of_stubs());
197 while (i-- > 0) remove_first();
198 }
199
200
201 void StubQueue::remove_all(){
202 debug_only(verify();)
203 remove_first(number_of_stubs());
204 assert(number_of_stubs() == 0, "sanity check");
205 }
206
207
208 enum { StubQueueLimit = 10 }; // there are only a few in the world
209 static StubQueue* registered_stub_queues[StubQueueLimit];
210
211 void StubQueue::register_queue(StubQueue* sq) {
212 for (int i = 0; i < StubQueueLimit; i++) {
213 if (registered_stub_queues[i] == NULL) {
214 registered_stub_queues[i] = sq;
215 return;
216 }
217 }
218 ShouldNotReachHere();
219 }
220
221
222 void StubQueue::queues_do(void f(StubQueue* sq)) {
223 for (int i = 0; i < StubQueueLimit; i++) {
224 if (registered_stub_queues[i] != NULL) {
225 f(registered_stub_queues[i]);
226 }
227 }
228 }
229
230
231 void StubQueue::stubs_do(void f(Stub* s)) {
232 debug_only(verify();)
233 MutexLockerEx lock(_mutex);
234 for (Stub* s = first(); s != NULL; s = next(s)) f(s);
235 }
236
237
238 void StubQueue::verify() {
239 // verify only if initialized
240 if (_stub_buffer == NULL) return;
241 MutexLockerEx lock(_mutex);
242 // verify index boundaries
243 guarantee(0 <= _buffer_size, "buffer size must be positive");
244 guarantee(0 <= _buffer_limit && _buffer_limit <= _buffer_size , "_buffer_limit out of bounds");
245 guarantee(0 <= _queue_begin && _queue_begin < _buffer_limit, "_queue_begin out of bounds");
246 guarantee(0 <= _queue_end && _queue_end <= _buffer_limit, "_queue_end out of bounds");
247 // verify alignment
248 guarantee(_buffer_size % CodeEntryAlignment == 0, "_buffer_size not aligned");
249 guarantee(_buffer_limit % CodeEntryAlignment == 0, "_buffer_limit not aligned");
250 guarantee(_queue_begin % CodeEntryAlignment == 0, "_queue_begin not aligned");
251 guarantee(_queue_end % CodeEntryAlignment == 0, "_queue_end not aligned");
252 // verify buffer limit/size relationship
253 if (is_contiguous()) {
254 guarantee(_buffer_limit == _buffer_size, "_buffer_limit must equal _buffer_size");
255 }
256 // verify contents
257 int n = 0;
258 for (Stub* s = first(); s != NULL; s = next(s)) {
259 stub_verify(s);
260 n++;
261 }
262 guarantee(n == number_of_stubs(), "number of stubs inconsistent");
263 guarantee(_queue_begin != _queue_end || n == 0, "buffer indices must be the same");
264 }
265
266
267 void StubQueue::print() {
268 MutexLockerEx lock(_mutex);
269 for (Stub* s = first(); s != NULL; s = next(s)) {
270 stub_print(s);
271 }
272 }
273