1 /*
2 * Copyright (c) 1997, 2009, 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 "incls/_precompiled.incl"
26 # include "incls/_heap.cpp.incl"
27
28
29 size_t CodeHeap::header_size() {
30 return sizeof(HeapBlock);
31 }
32
33
34 // Implementation of Heap
35
36 CodeHeap::CodeHeap() {
37 _number_of_committed_segments = 0;
38 _number_of_reserved_segments = 0;
39 _segment_size = 0;
40 _log2_segment_size = 0;
41 _next_segment = 0;
42 _freelist = NULL;
43 _free_segments = 0;
44 }
45
46
47 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
48 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds");
49 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
50 // setup _segmap pointers for faster indexing
51 address p = (address)_segmap.low() + beg;
52 address q = (address)_segmap.low() + end;
53 // initialize interval
54 while (p < q) *p++ = 0xFF;
55 }
56
57
58 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
59 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds");
60 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
61 // setup _segmap pointers for faster indexing
62 address p = (address)_segmap.low() + beg;
63 address q = (address)_segmap.low() + end;
64 // initialize interval
65 int i = 0;
66 while (p < q) {
67 *p++ = i++;
68 if (i == 0xFF) i = 1;
69 }
70 }
71
72
73 static size_t align_to_page_size(size_t size) {
74 const size_t alignment = (size_t)os::vm_page_size();
75 assert(is_power_of_2(alignment), "no kidding ???");
76 return (size + alignment - 1) & ~(alignment - 1);
77 }
78
79
80 static size_t align_to_allocation_size(size_t size) {
81 const size_t alignment = (size_t)os::vm_allocation_granularity();
82 assert(is_power_of_2(alignment), "no kidding ???");
83 return (size + alignment - 1) & ~(alignment - 1);
84 }
85
86
87 void CodeHeap::on_code_mapping(char* base, size_t size) {
88 #ifdef LINUX
89 extern void linux_wrap_code(char* base, size_t size);
90 linux_wrap_code(base, size);
91 #endif
92 }
93
94
95 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,
96 size_t segment_size) {
97 assert(reserved_size >= committed_size, "reserved < committed");
98 assert(segment_size >= sizeof(FreeBlock), "segment size is too small");
99 assert(is_power_of_2(segment_size), "segment_size must be a power of 2");
100
101 _segment_size = segment_size;
102 _log2_segment_size = exact_log2(segment_size);
103
104 // Reserve and initialize space for _memory.
105 const size_t page_size = os::can_execute_large_page_memory() ?
106 os::page_size_for_region(committed_size, reserved_size, 8) :
107 os::vm_page_size();
108 const size_t granularity = os::vm_allocation_granularity();
109 const size_t r_align = MAX2(page_size, granularity);
110 const size_t r_size = align_size_up(reserved_size, r_align);
111 const size_t c_size = align_size_up(committed_size, page_size);
112
113 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :
114 MAX2(page_size, granularity);
115 ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);
116 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,
117 rs.base(), rs.size());
118 if (!_memory.initialize(rs, c_size)) {
119 return false;
120 }
121
122 on_code_mapping(_memory.low(), _memory.committed_size());
123 _number_of_committed_segments = number_of_segments(_memory.committed_size());
124 _number_of_reserved_segments = number_of_segments(_memory.reserved_size());
125 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
126
127 // reserve space for _segmap
128 if (!_segmap.initialize(align_to_page_size(_number_of_reserved_segments), align_to_page_size(_number_of_committed_segments))) {
129 return false;
130 }
131 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
132 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
133 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
134
135 // initialize remaining instance variables
136 clear();
137 return true;
138 }
139
140
141 void CodeHeap::release() {
142 Unimplemented();
143 }
144
145
146 bool CodeHeap::expand_by(size_t size) {
147 // expand _memory space
148 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
149 if (dm > 0) {
150 char* base = _memory.low() + _memory.committed_size();
151 if (!_memory.expand_by(dm)) return false;
152 on_code_mapping(base, dm);
153 size_t i = _number_of_committed_segments;
154 _number_of_committed_segments = number_of_segments(_memory.committed_size());
155 assert(_number_of_reserved_segments == number_of_segments(_memory.reserved_size()), "number of reserved segments should not change");
156 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
157 // expand _segmap space
158 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
159 if (ds > 0) {
160 if (!_segmap.expand_by(ds)) return false;
161 }
162 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
163 // initialize additional segmap entries
164 mark_segmap_as_free(i, _number_of_committed_segments);
165 }
166 return true;
167 }
168
169
170 void CodeHeap::shrink_by(size_t size) {
171 Unimplemented();
172 }
173
174
175 void CodeHeap::clear() {
176 _next_segment = 0;
177 mark_segmap_as_free(0, _number_of_committed_segments);
178 }
179
180
181 void* CodeHeap::allocate(size_t size) {
182 size_t length = number_of_segments(size + sizeof(HeapBlock));
183 assert(length *_segment_size >= sizeof(FreeBlock), "not enough room for FreeList");
184
185 // First check if we can satify request from freelist
186 debug_only(verify());
187 HeapBlock* block = search_freelist(length);
188 debug_only(if (VerifyCodeCacheOften) verify());
189 if (block != NULL) {
190 assert(block->length() >= length && block->length() < length + CodeCacheMinBlockLength, "sanity check");
191 assert(!block->free(), "must be marked free");
192 #ifdef ASSERT
193 memset((void *)block->allocated_space(), badCodeHeapNewVal, size);
194 #endif
195 return block->allocated_space();
196 }
197
198 if (length < CodeCacheMinBlockLength) {
199 length = CodeCacheMinBlockLength;
200 }
201 if (_next_segment + length <= _number_of_committed_segments) {
202 mark_segmap_as_used(_next_segment, _next_segment + length);
203 HeapBlock* b = block_at(_next_segment);
204 b->initialize(length);
205 _next_segment += length;
206 #ifdef ASSERT
207 memset((void *)b->allocated_space(), badCodeHeapNewVal, size);
208 #endif
209 return b->allocated_space();
210 } else {
211 return NULL;
212 }
213 }
214
215
216 void CodeHeap::deallocate(void* p) {
217 assert(p == find_start(p), "illegal deallocation");
218 // Find start of HeapBlock
219 HeapBlock* b = (((HeapBlock *)p) - 1);
220 assert(b->allocated_space() == p, "sanity check");
221 #ifdef ASSERT
222 memset((void *)b->allocated_space(),
223 badCodeHeapFreeVal,
224 size(b->length()) - sizeof(HeapBlock));
225 #endif
226 add_to_freelist(b);
227
228 debug_only(if (VerifyCodeCacheOften) verify());
229 }
230
231
232 void* CodeHeap::find_start(void* p) const {
233 if (!contains(p)) {
234 return NULL;
235 }
236 size_t i = segment_for(p);
237 address b = (address)_segmap.low();
238 if (b[i] == 0xFF) {
239 return NULL;
240 }
241 while (b[i] > 0) i -= (int)b[i];
242 HeapBlock* h = block_at(i);
243 if (h->free()) {
244 return NULL;
245 }
246 return h->allocated_space();
247 }
248
249
250 size_t CodeHeap::alignment_unit() const {
251 // this will be a power of two
252 return _segment_size;
253 }
254
255
256 size_t CodeHeap::alignment_offset() const {
257 // The lowest address in any allocated block will be
258 // equal to alignment_offset (mod alignment_unit).
259 return sizeof(HeapBlock) & (_segment_size - 1);
260 }
261
262 // Finds the next free heapblock. If the current one is free, that it returned
263 void* CodeHeap::next_free(HeapBlock *b) const {
264 // Since free blocks are merged, there is max. on free block
265 // between two used ones
266 if (b != NULL && b->free()) b = next_block(b);
267 assert(b == NULL || !b->free(), "must be in use or at end of heap");
268 return (b == NULL) ? NULL : b->allocated_space();
269 }
270
271 // Returns the first used HeapBlock
272 HeapBlock* CodeHeap::first_block() const {
273 if (_next_segment > 0)
274 return block_at(0);
275 return NULL;
276 }
277
278 HeapBlock *CodeHeap::block_start(void *q) const {
279 HeapBlock* b = (HeapBlock*)find_start(q);
280 if (b == NULL) return NULL;
281 return b - 1;
282 }
283
284 // Returns the next Heap block an offset into one
285 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
286 if (b == NULL) return NULL;
287 size_t i = segment_for(b) + b->length();
288 if (i < _next_segment)
289 return block_at(i);
290 return NULL;
291 }
292
293
294 // Returns current capacity
295 size_t CodeHeap::capacity() const {
296 return _memory.committed_size();
297 }
298
299 size_t CodeHeap::max_capacity() const {
300 return _memory.reserved_size();
301 }
302
303 size_t CodeHeap::allocated_capacity() const {
304 // Start with the committed size in _memory;
305 size_t l = _memory.committed_size();
306
307 // Subtract the committed, but unused, segments
308 l -= size(_number_of_committed_segments - _next_segment);
309
310 // Subtract the size of the freelist
311 l -= size(_free_segments);
312
313 return l;
314 }
315
316 // Free list management
317
318 FreeBlock *CodeHeap::following_block(FreeBlock *b) {
319 return (FreeBlock*)(((address)b) + _segment_size * b->length());
320 }
321
322 // Inserts block b after a
323 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
324 assert(a != NULL && b != NULL, "must be real pointers");
325
326 // Link b into the list after a
327 b->set_link(a->link());
328 a->set_link(b);
329
330 // See if we can merge blocks
331 merge_right(b); // Try to make b bigger
332 merge_right(a); // Try to make a include b
333 }
334
335 // Try to merge this block with the following block
336 void CodeHeap::merge_right(FreeBlock *a) {
337 assert(a->free(), "must be a free block");
338 if (following_block(a) == a->link()) {
339 assert(a->link() != NULL && a->link()->free(), "must be free too");
340 // Update block a to include the following block
341 a->set_length(a->length() + a->link()->length());
342 a->set_link(a->link()->link());
343 // Update find_start map
344 size_t beg = segment_for(a);
345 mark_segmap_as_used(beg, beg + a->length());
346 }
347 }
348
349 void CodeHeap::add_to_freelist(HeapBlock *a) {
350 FreeBlock* b = (FreeBlock*)a;
351 assert(b != _freelist, "cannot be removed twice");
352
353 // Mark as free and update free space count
354 _free_segments += b->length();
355 b->set_free();
356
357 // First element in list?
358 if (_freelist == NULL) {
359 _freelist = b;
360 b->set_link(NULL);
361 return;
362 }
363
364 // Scan for right place to put into list. List
365 // is sorted by increasing addresseses
366 FreeBlock* prev = NULL;
367 FreeBlock* cur = _freelist;
368 while(cur != NULL && cur < b) {
369 assert(prev == NULL || prev < cur, "must be ordered");
370 prev = cur;
371 cur = cur->link();
372 }
373
374 assert( (prev == NULL && b < _freelist) ||
375 (prev < b && (cur == NULL || b < cur)), "list must be ordered");
376
377 if (prev == NULL) {
378 // Insert first in list
379 b->set_link(_freelist);
380 _freelist = b;
381 merge_right(_freelist);
382 } else {
383 insert_after(prev, b);
384 }
385 }
386
387 // Search freelist for an entry on the list with the best fit
388 // Return NULL if no one was found
389 FreeBlock* CodeHeap::search_freelist(size_t length) {
390 FreeBlock *best_block = NULL;
391 FreeBlock *best_prev = NULL;
392 size_t best_length = 0;
393
394 // Search for smallest block which is bigger than length
395 FreeBlock *prev = NULL;
396 FreeBlock *cur = _freelist;
397 while(cur != NULL) {
398 size_t l = cur->length();
399 if (l >= length && (best_block == NULL || best_length > l)) {
400 // Remember best block, its previous element, and its length
401 best_block = cur;
402 best_prev = prev;
403 best_length = best_block->length();
404 }
405
406 // Next element in list
407 prev = cur;
408 cur = cur->link();
409 }
410
411 if (best_block == NULL) {
412 // None found
413 return NULL;
414 }
415
416 assert((best_prev == NULL && _freelist == best_block ) ||
417 (best_prev != NULL && best_prev->link() == best_block), "sanity check");
418
419 // Exact (or at least good enough) fit. Remove from list.
420 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
421 if (best_length < length + CodeCacheMinBlockLength) {
422 length = best_length;
423 if (best_prev == NULL) {
424 assert(_freelist == best_block, "sanity check");
425 _freelist = _freelist->link();
426 } else {
427 // Unmap element
428 best_prev->set_link(best_block->link());
429 }
430 } else {
431 // Truncate block and return a pointer to the following block
432 best_block->set_length(best_length - length);
433 best_block = following_block(best_block);
434 // Set used bit and length on new block
435 size_t beg = segment_for(best_block);
436 mark_segmap_as_used(beg, beg + length);
437 best_block->set_length(length);
438 }
439
440 best_block->set_used();
441 _free_segments -= length;
442 return best_block;
443 }
444
445 //----------------------------------------------------------------------------
446 // Non-product code
447
448 #ifndef PRODUCT
449
450 void CodeHeap::print() {
451 tty->print_cr("The Heap");
452 }
453
454 #endif
455
456 void CodeHeap::verify() {
457 // Count the number of blocks on the freelist, and the amount of space
458 // represented.
459 int count = 0;
460 size_t len = 0;
461 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
462 len += b->length();
463 count++;
464 }
465
466 // Verify that freelist contains the right amount of free space
467 // guarantee(len == _free_segments, "wrong freelist");
468
469 // Verify that the number of free blocks is not out of hand.
470 static int free_block_threshold = 10000;
471 if (count > free_block_threshold) {
472 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
473 // Double the warning limit
474 free_block_threshold *= 2;
475 }
476
477 // Verify that the freelist contains the same number of free blocks that is
478 // found on the full list.
479 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
480 if (h->free()) count--;
481 }
482 // guarantee(count == 0, "missing free blocks");
483 }