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 // We also have to account for the extra space (i.e. header) used by the CodeBlob
96 // which provides our memory (see BufferBlob::create() in codeBlob.cpp).
97 size_t header_size = CodeBlob::align_code_offset(blob->header_size());
98 CodeCache::free_unused_tail(blob, header_size + used_space());
99 // Update the limits to the new, trimmed CodeBlob size
100 _buffer_size = blob->content_size();
101 _buffer_limit = blob->content_size();
102 }
103
104 Stub* StubQueue::stub_containing(address pc) const {
105 if (contains(pc)) {
106 for (Stub* s = first(); s != NULL; s = next(s)) {
107 if (stub_contains(s, pc)) return s;
108 }
109 }
110 return NULL;
111 }
112
113
114 Stub* StubQueue::request_committed(int code_size) {
115 Stub* s = request(code_size);
116 CodeStrings strings;
117 if (s != NULL) commit(code_size, strings);
118 return s;
119 }
120
121
122 Stub* StubQueue::request(int requested_code_size) {
123 assert(requested_code_size > 0, "requested_code_size must be > 0");
124 if (_mutex != NULL) _mutex->lock();
125 Stub* s = current_stub();
126 int requested_size = align_up(stub_code_size_to_size(requested_code_size), CodeEntryAlignment);
127 if (requested_size <= available_space()) {
128 if (is_contiguous()) {
129 // Queue: |...|XXXXXXX|.............|
130 // ^0 ^begin ^end ^size = limit
131 assert(_buffer_limit == _buffer_size, "buffer must be fully usable");
132 if (_queue_end + requested_size <= _buffer_size) {
133 // code fits in at the end => nothing to do
134 CodeStrings strings;
135 stub_initialize(s, requested_size, strings);
136 return s;
137 } else {
138 // stub doesn't fit in at the queue end
139 // => reduce buffer limit & wrap around
140 assert(!is_empty(), "just checkin'");
141 _buffer_limit = _queue_end;
142 _queue_end = 0;
143 }
144 }
145 }
146 if (requested_size <= available_space()) {
147 assert(!is_contiguous(), "just checkin'");
148 assert(_buffer_limit <= _buffer_size, "queue invariant broken");
149 // Queue: |XXX|.......|XXXXXXX|.......|
150 // ^0 ^end ^begin ^limit ^size
151 s = current_stub();
152 CodeStrings strings;
153 stub_initialize(s, requested_size, strings);
154 return s;
155 }
156 // Not enough space left
157 if (_mutex != NULL) _mutex->unlock();
158 return NULL;
159 }
160
161
162 void StubQueue::commit(int committed_code_size, CodeStrings& strings) {
163 assert(committed_code_size > 0, "committed_code_size must be > 0");
164 int committed_size = align_up(stub_code_size_to_size(committed_code_size), CodeEntryAlignment);
165 Stub* s = current_stub();
166 assert(committed_size <= stub_size(s), "committed size must not exceed requested size");
167 stub_initialize(s, committed_size, strings);
168 _queue_end += committed_size;
169 _number_of_stubs++;
170 if (_mutex != NULL) _mutex->unlock();
171 debug_only(stub_verify(s);)
172 }
173
174
175 void StubQueue::remove_first() {
176 if (number_of_stubs() == 0) return;
177 Stub* s = first();
178 debug_only(stub_verify(s);)
179 stub_finalize(s);
180 _queue_begin += stub_size(s);
181 assert(_queue_begin <= _buffer_limit, "sanity check");
182 if (_queue_begin == _queue_end) {
183 // buffer empty
184 // => reset queue indices
185 _queue_begin = 0;
186 _queue_end = 0;
187 _buffer_limit = _buffer_size;
188 } else if (_queue_begin == _buffer_limit) {
189 // buffer limit reached
190 // => reset buffer limit & wrap around
191 _buffer_limit = _buffer_size;
192 _queue_begin = 0;
193 }
194 _number_of_stubs--;
195 }
196
197
198 void StubQueue::remove_first(int n) {
199 int i = MIN2(n, number_of_stubs());
200 while (i-- > 0) remove_first();
201 }
202
203
204 void StubQueue::remove_all(){
205 debug_only(verify();)
206 remove_first(number_of_stubs());
207 assert(number_of_stubs() == 0, "sanity check");
208 }
209
210
211 enum { StubQueueLimit = 10 }; // there are only a few in the world
212 static StubQueue* registered_stub_queues[StubQueueLimit];
213
214 void StubQueue::register_queue(StubQueue* sq) {
215 for (int i = 0; i < StubQueueLimit; i++) {
216 if (registered_stub_queues[i] == NULL) {
217 registered_stub_queues[i] = sq;
218 return;
219 }
220 }
221 ShouldNotReachHere();
222 }
223
224
225 void StubQueue::queues_do(void f(StubQueue* sq)) {
226 for (int i = 0; i < StubQueueLimit; i++) {
227 if (registered_stub_queues[i] != NULL) {
228 f(registered_stub_queues[i]);
229 }
230 }
231 }
232
233
234 void StubQueue::stubs_do(void f(Stub* s)) {
235 debug_only(verify();)
236 MutexLockerEx lock(_mutex);
237 for (Stub* s = first(); s != NULL; s = next(s)) f(s);
238 }
239
240
241 void StubQueue::verify() {
242 // verify only if initialized
243 if (_stub_buffer == NULL) return;
244 MutexLockerEx lock(_mutex);
245 // verify index boundaries
246 guarantee(0 <= _buffer_size, "buffer size must be positive");
247 guarantee(0 <= _buffer_limit && _buffer_limit <= _buffer_size , "_buffer_limit out of bounds");
248 guarantee(0 <= _queue_begin && _queue_begin < _buffer_limit, "_queue_begin out of bounds");
249 guarantee(0 <= _queue_end && _queue_end <= _buffer_limit, "_queue_end out of bounds");
250 // verify alignment
251 guarantee(_buffer_size % CodeEntryAlignment == 0, "_buffer_size not aligned");
252 guarantee(_buffer_limit % CodeEntryAlignment == 0, "_buffer_limit not aligned");
253 guarantee(_queue_begin % CodeEntryAlignment == 0, "_queue_begin not aligned");
254 guarantee(_queue_end % CodeEntryAlignment == 0, "_queue_end not aligned");
255 // verify buffer limit/size relationship
256 if (is_contiguous()) {
257 guarantee(_buffer_limit == _buffer_size, "_buffer_limit must equal _buffer_size");
258 }
259 // verify contents
260 int n = 0;
261 for (Stub* s = first(); s != NULL; s = next(s)) {
262 stub_verify(s);
263 n++;
264 }
265 guarantee(n == number_of_stubs(), "number of stubs inconsistent");
266 guarantee(_queue_begin != _queue_end || n == 0, "buffer indices must be the same");
267 }
268
269
270 void StubQueue::print() {
271 MutexLockerEx lock(_mutex);
272 for (Stub* s = first(); s != NULL; s = next(s)) {
273 stub_print(s);
274 }
275 }
276