1 /*
2 * Copyright (c) 1997, 2013, 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 "memory/heap.hpp"
27 #include "oops/oop.inline.hpp"
28 #include "runtime/os.hpp"
29 #include "services/memTracker.hpp"
30
31 size_t CodeHeap::header_size() {
32 return sizeof(HeapBlock);
33 }
34
35
36 // Implementation of Heap
37
38 CodeHeap::CodeHeap() {
39 _number_of_committed_segments = 0;
40 _number_of_reserved_segments = 0;
41 _segment_size = 0;
42 _log2_segment_size = 0;
43 _next_segment = 0;
44 _freelist = NULL;
45 _freelist_segments = 0;
46 }
47
48
49 void CodeHeap::mark_segmap_as_free(size_t beg, size_t end) {
50 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds");
51 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
52 // setup _segmap pointers for faster indexing
53 address p = (address)_segmap.low() + beg;
54 address q = (address)_segmap.low() + end;
55 // initialize interval
56 while (p < q) *p++ = 0xFF;
57 }
58
59
60 void CodeHeap::mark_segmap_as_used(size_t beg, size_t end) {
61 assert(0 <= beg && beg < _number_of_committed_segments, "interval begin out of bounds");
62 assert(beg < end && end <= _number_of_committed_segments, "interval end out of bounds");
63 // setup _segmap pointers for faster indexing
64 address p = (address)_segmap.low() + beg;
65 address q = (address)_segmap.low() + end;
66 // initialize interval
67 int i = 0;
68 while (p < q) {
69 *p++ = i++;
70 if (i == 0xFF) i = 1;
71 }
72 }
73
74
75 static size_t align_to_page_size(size_t size) {
76 const size_t alignment = (size_t)os::vm_page_size();
77 assert(is_power_of_2(alignment), "no kidding ???");
78 return (size + alignment - 1) & ~(alignment - 1);
79 }
80
81
82 void CodeHeap::on_code_mapping(char* base, size_t size) {
83 #ifdef LINUX
84 extern void linux_wrap_code(char* base, size_t size);
85 linux_wrap_code(base, size);
86 #endif
87 }
88
89
90 bool CodeHeap::reserve(size_t reserved_size, size_t committed_size,
91 size_t segment_size) {
92 assert(reserved_size >= committed_size, "reserved < committed");
93 assert(segment_size >= sizeof(FreeBlock), "segment size is too small");
94 assert(is_power_of_2(segment_size), "segment_size must be a power of 2");
95
96 _segment_size = segment_size;
97 _log2_segment_size = exact_log2(segment_size);
98
99 // Reserve and initialize space for _memory.
100 const size_t page_size = os::can_execute_large_page_memory() ?
101 os::page_size_for_region(committed_size, reserved_size, 8) :
102 os::vm_page_size();
103 const size_t granularity = os::vm_allocation_granularity();
104 const size_t r_align = MAX2(page_size, granularity);
105 const size_t r_size = align_size_up(reserved_size, r_align);
106 const size_t c_size = align_size_up(committed_size, page_size);
107
108 const size_t rs_align = page_size == (size_t) os::vm_page_size() ? 0 :
109 MAX2(page_size, granularity);
110 ReservedCodeSpace rs(r_size, rs_align, rs_align > 0);
111 os::trace_page_sizes("code heap", committed_size, reserved_size, page_size,
112 rs.base(), rs.size());
113 if (!_memory.initialize(rs, c_size)) {
114 return false;
115 }
116
117 on_code_mapping(_memory.low(), _memory.committed_size());
118 _number_of_committed_segments = size_to_segments(_memory.committed_size());
119 _number_of_reserved_segments = size_to_segments(_memory.reserved_size());
120 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
121 const size_t reserved_segments_alignment = MAX2((size_t)os::vm_page_size(), granularity);
122 const size_t reserved_segments_size = align_size_up(_number_of_reserved_segments, reserved_segments_alignment);
123 const size_t committed_segments_size = align_to_page_size(_number_of_committed_segments);
124
125 // reserve space for _segmap
126 if (!_segmap.initialize(reserved_segments_size, committed_segments_size)) {
127 return false;
128 }
129
130 MemTracker::record_virtual_memory_type((address)_segmap.low_boundary(), mtCode);
131
132 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "could not commit enough space for segment map");
133 assert(_segmap.reserved_size() >= (size_t) _number_of_reserved_segments , "could not reserve enough space for segment map");
134 assert(_segmap.reserved_size() >= _segmap.committed_size() , "just checking");
135
136 // initialize remaining instance variables
137 clear();
138 return true;
139 }
140
141
142 void CodeHeap::release() {
143 Unimplemented();
144 }
145
146
147 bool CodeHeap::expand_by(size_t size) {
148 // expand _memory space
149 size_t dm = align_to_page_size(_memory.committed_size() + size) - _memory.committed_size();
150 if (dm > 0) {
151 char* base = _memory.low() + _memory.committed_size();
152 if (!_memory.expand_by(dm)) return false;
153 on_code_mapping(base, dm);
154 size_t i = _number_of_committed_segments;
155 _number_of_committed_segments = size_to_segments(_memory.committed_size());
156 assert(_number_of_reserved_segments == size_to_segments(_memory.reserved_size()), "number of reserved segments should not change");
157 assert(_number_of_reserved_segments >= _number_of_committed_segments, "just checking");
158 // expand _segmap space
159 size_t ds = align_to_page_size(_number_of_committed_segments) - _segmap.committed_size();
160 if (ds > 0) {
161 if (!_segmap.expand_by(ds)) return false;
162 }
163 assert(_segmap.committed_size() >= (size_t) _number_of_committed_segments, "just checking");
164 // initialize additional segmap entries
165 mark_segmap_as_free(i, _number_of_committed_segments);
166 }
167 return true;
168 }
169
170
171 void CodeHeap::shrink_by(size_t size) {
172 Unimplemented();
173 }
174
175
176 void CodeHeap::clear() {
177 _next_segment = 0;
178 mark_segmap_as_free(0, _number_of_committed_segments);
179 }
180
181
182 void* CodeHeap::allocate(size_t instance_size, bool is_critical) {
183 size_t number_of_segments = size_to_segments(instance_size + sizeof(HeapBlock));
184 assert(segments_to_size(number_of_segments) >= sizeof(FreeBlock), "not enough room for FreeList");
185
186 // First check if we can satify request from freelist
187 debug_only(verify());
188 HeapBlock* block = search_freelist(number_of_segments, is_critical);
189 debug_only(if (VerifyCodeCacheOften) verify());
190 if (block != NULL) {
191 assert(block->length() >= number_of_segments && block->length() < number_of_segments + CodeCacheMinBlockLength, "sanity check");
192 assert(!block->free(), "must be marked free");
193 #ifdef ASSERT
194 memset((void *)block->allocated_space(), badCodeHeapNewVal, instance_size);
195 #endif
196 return block->allocated_space();
197 }
198
199 // Ensure minimum size for allocation to the heap.
200 if (number_of_segments < CodeCacheMinBlockLength) {
201 number_of_segments = CodeCacheMinBlockLength;
202 }
203
204 if (!is_critical) {
205 // Make sure the allocation fits in the unallocated heap without using
206 // the CodeCacheMimimumFreeSpace that is reserved for critical allocations.
207 if (segments_to_size(number_of_segments) > (heap_unallocated_capacity() - CodeCacheMinimumFreeSpace)) {
208 // Fail allocation
209 return NULL;
210 }
211 }
212
213 if (_next_segment + number_of_segments <= _number_of_committed_segments) {
214 mark_segmap_as_used(_next_segment, _next_segment + number_of_segments);
215 HeapBlock* b = block_at(_next_segment);
216 b->initialize(number_of_segments);
217 _next_segment += number_of_segments;
218 #ifdef ASSERT
219 memset((void *)b->allocated_space(), badCodeHeapNewVal, instance_size);
220 #endif
221 return b->allocated_space();
222 } else {
223 return NULL;
224 }
225 }
226
227
228 void CodeHeap::deallocate(void* p) {
229 assert(p == find_start(p), "illegal deallocation");
230 // Find start of HeapBlock
231 HeapBlock* b = (((HeapBlock *)p) - 1);
232 assert(b->allocated_space() == p, "sanity check");
233 #ifdef ASSERT
234 memset((void *)b->allocated_space(),
235 badCodeHeapFreeVal,
236 segments_to_size(b->length()) - sizeof(HeapBlock));
237 #endif
238 add_to_freelist(b);
239
240 debug_only(if (VerifyCodeCacheOften) verify());
241 }
242
243
244 void* CodeHeap::find_start(void* p) const {
245 if (!contains(p)) {
246 return NULL;
247 }
248 size_t i = segment_for(p);
249 address b = (address)_segmap.low();
250 if (b[i] == 0xFF) {
251 return NULL;
252 }
253 while (b[i] > 0) i -= (int)b[i];
254 HeapBlock* h = block_at(i);
255 if (h->free()) {
256 return NULL;
257 }
258 return h->allocated_space();
259 }
260
261
262 size_t CodeHeap::alignment_unit() const {
263 // this will be a power of two
264 return _segment_size;
265 }
266
267
268 size_t CodeHeap::alignment_offset() const {
269 // The lowest address in any allocated block will be
270 // equal to alignment_offset (mod alignment_unit).
271 return sizeof(HeapBlock) & (_segment_size - 1);
272 }
273
274 // Finds the next free heapblock. If the current one is free, that it returned
275 void* CodeHeap::next_free(HeapBlock *b) const {
276 // Since free blocks are merged, there is max. on free block
277 // between two used ones
278 if (b != NULL && b->free()) b = next_block(b);
279 assert(b == NULL || !b->free(), "must be in use or at end of heap");
280 return (b == NULL) ? NULL : b->allocated_space();
281 }
282
283 // Returns the first used HeapBlock
284 HeapBlock* CodeHeap::first_block() const {
285 if (_next_segment > 0)
286 return block_at(0);
287 return NULL;
288 }
289
290 HeapBlock *CodeHeap::block_start(void *q) const {
291 HeapBlock* b = (HeapBlock*)find_start(q);
292 if (b == NULL) return NULL;
293 return b - 1;
294 }
295
296 // Returns the next Heap block an offset into one
297 HeapBlock* CodeHeap::next_block(HeapBlock *b) const {
298 if (b == NULL) return NULL;
299 size_t i = segment_for(b) + b->length();
300 if (i < _next_segment)
301 return block_at(i);
302 return NULL;
303 }
304
305
306 // Returns current capacity
307 size_t CodeHeap::capacity() const {
308 return _memory.committed_size();
309 }
310
311 size_t CodeHeap::max_capacity() const {
312 return _memory.reserved_size();
313 }
314
315 size_t CodeHeap::allocated_capacity() const {
316 // size of used heap - size on freelist
317 return segments_to_size(_next_segment - _freelist_segments);
318 }
319
320 // Returns size of the unallocated heap block
321 size_t CodeHeap::heap_unallocated_capacity() const {
322 // Total number of segments - number currently used
323 return segments_to_size(_number_of_reserved_segments - _next_segment);
324 }
325
326 // Free list management
327
328 FreeBlock *CodeHeap::following_block(FreeBlock *b) {
329 return (FreeBlock*)(((address)b) + _segment_size * b->length());
330 }
331
332 // Inserts block b after a
333 void CodeHeap::insert_after(FreeBlock* a, FreeBlock* b) {
334 assert(a != NULL && b != NULL, "must be real pointers");
335
336 // Link b into the list after a
337 b->set_link(a->link());
338 a->set_link(b);
339
340 // See if we can merge blocks
341 merge_right(b); // Try to make b bigger
342 merge_right(a); // Try to make a include b
343 }
344
345 // Try to merge this block with the following block
346 void CodeHeap::merge_right(FreeBlock *a) {
347 assert(a->free(), "must be a free block");
348 if (following_block(a) == a->link()) {
349 assert(a->link() != NULL && a->link()->free(), "must be free too");
350 // Update block a to include the following block
351 a->set_length(a->length() + a->link()->length());
352 a->set_link(a->link()->link());
353 // Update find_start map
354 size_t beg = segment_for(a);
355 mark_segmap_as_used(beg, beg + a->length());
356 }
357 }
358
359 void CodeHeap::add_to_freelist(HeapBlock *a) {
360 FreeBlock* b = (FreeBlock*)a;
361 assert(b != _freelist, "cannot be removed twice");
362
363 // Mark as free and update free space count
364 _freelist_segments += b->length();
365 b->set_free();
366
367 // First element in list?
368 if (_freelist == NULL) {
369 _freelist = b;
370 b->set_link(NULL);
371 return;
372 }
373
374 // Scan for right place to put into list. List
375 // is sorted by increasing addresseses
376 FreeBlock* prev = NULL;
377 FreeBlock* cur = _freelist;
378 while(cur != NULL && cur < b) {
379 assert(prev == NULL || prev < cur, "must be ordered");
380 prev = cur;
381 cur = cur->link();
382 }
383
384 assert( (prev == NULL && b < _freelist) ||
385 (prev < b && (cur == NULL || b < cur)), "list must be ordered");
386
387 if (prev == NULL) {
388 // Insert first in list
389 b->set_link(_freelist);
390 _freelist = b;
391 merge_right(_freelist);
392 } else {
393 insert_after(prev, b);
394 }
395 }
396
397 // Search freelist for an entry on the list with the best fit
398 // Return NULL if no one was found
399 FreeBlock* CodeHeap::search_freelist(size_t length, bool is_critical) {
400 FreeBlock *best_block = NULL;
401 FreeBlock *best_prev = NULL;
402 size_t best_length = 0;
403
404 // Search for smallest block which is bigger than length
405 FreeBlock *prev = NULL;
406 FreeBlock *cur = _freelist;
407 while(cur != NULL) {
408 size_t l = cur->length();
409 if (l >= length && (best_block == NULL || best_length > l)) {
410
411 // Non critical allocations are not allowed to use the last part of the code heap.
412 if (!is_critical) {
413 // Make sure the end of the allocation doesn't cross into the last part of the code heap
414 if (((size_t)cur + length) > ((size_t)high_boundary() - CodeCacheMinimumFreeSpace)) {
415 // the freelist is sorted by address - if one fails, all consecutive will also fail.
416 break;
417 }
418 }
419
420 // Remember best block, its previous element, and its length
421 best_block = cur;
422 best_prev = prev;
423 best_length = best_block->length();
424 }
425
426 // Next element in list
427 prev = cur;
428 cur = cur->link();
429 }
430
431 if (best_block == NULL) {
432 // None found
433 return NULL;
434 }
435
436 assert((best_prev == NULL && _freelist == best_block ) ||
437 (best_prev != NULL && best_prev->link() == best_block), "sanity check");
438
439 // Exact (or at least good enough) fit. Remove from list.
440 // Don't leave anything on the freelist smaller than CodeCacheMinBlockLength.
441 if (best_length < length + CodeCacheMinBlockLength) {
442 length = best_length;
443 if (best_prev == NULL) {
444 assert(_freelist == best_block, "sanity check");
445 _freelist = _freelist->link();
446 } else {
447 // Unmap element
448 best_prev->set_link(best_block->link());
449 }
450 } else {
451 // Truncate block and return a pointer to the following block
452 best_block->set_length(best_length - length);
453 best_block = following_block(best_block);
454 // Set used bit and length on new block
455 size_t beg = segment_for(best_block);
456 mark_segmap_as_used(beg, beg + length);
457 best_block->set_length(length);
458 }
459
460 best_block->set_used();
461 _freelist_segments -= length;
462 return best_block;
463 }
464
465 //----------------------------------------------------------------------------
466 // Non-product code
467
468 #ifndef PRODUCT
469
470 void CodeHeap::print() {
471 tty->print_cr("The Heap");
472 }
473
474 #endif
475
476 void CodeHeap::verify() {
477 // Count the number of blocks on the freelist, and the amount of space
478 // represented.
479 int count = 0;
480 size_t len = 0;
481 for(FreeBlock* b = _freelist; b != NULL; b = b->link()) {
482 len += b->length();
483 count++;
484 }
485
486 // Verify that freelist contains the right amount of free space
487 // guarantee(len == _freelist_segments, "wrong freelist");
488
489 // Verify that the number of free blocks is not out of hand.
490 static int free_block_threshold = 10000;
491 if (count > free_block_threshold) {
492 warning("CodeHeap: # of free blocks > %d", free_block_threshold);
493 // Double the warning limit
494 free_block_threshold *= 2;
495 }
496
497 // Verify that the freelist contains the same number of free blocks that is
498 // found on the full list.
499 for(HeapBlock *h = first_block(); h != NULL; h = next_block(h)) {
500 if (h->free()) count--;
501 }
502 // guarantee(count == 0, "missing free blocks");
503 }