1 /*
2 * Copyright (c) 1997, 2011, 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 "oops/markOop.hpp"
27 #include "oops/oop.inline.hpp"
28 #include "runtime/virtualspace.hpp"
29 #ifdef TARGET_OS_FAMILY_linux
30 # include "os_linux.inline.hpp"
31 #endif
32 #ifdef TARGET_OS_FAMILY_solaris
33 # include "os_solaris.inline.hpp"
34 #endif
35 #ifdef TARGET_OS_FAMILY_windows
36 # include "os_windows.inline.hpp"
37 #endif
38
39
40 // ReservedSpace
41 ReservedSpace::ReservedSpace(size_t size) {
42 initialize(size, 0, false, NULL, 0, false);
43 }
44
45 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
46 bool large,
47 char* requested_address,
48 const size_t noaccess_prefix) {
49 initialize(size+noaccess_prefix, alignment, large, requested_address,
50 noaccess_prefix, false);
51 }
52
53 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
54 bool large,
55 bool executable) {
56 initialize(size, alignment, large, NULL, 0, executable);
57 }
58
59 char *
60 ReservedSpace::align_reserved_region(char* addr, const size_t len,
61 const size_t prefix_size,
62 const size_t prefix_align,
63 const size_t suffix_size,
64 const size_t suffix_align)
65 {
66 assert(addr != NULL, "sanity");
67 const size_t required_size = prefix_size + suffix_size;
68 assert(len >= required_size, "len too small");
69
70 const size_t s = size_t(addr);
71 const size_t beg_ofs = (s + prefix_size) & (suffix_align - 1);
72 const size_t beg_delta = beg_ofs == 0 ? 0 : suffix_align - beg_ofs;
73
74 if (len < beg_delta + required_size) {
75 return NULL; // Cannot do proper alignment.
76 }
77 const size_t end_delta = len - (beg_delta + required_size);
78
79 if (beg_delta != 0) {
80 os::release_memory(addr, beg_delta);
81 }
82
83 if (end_delta != 0) {
84 char* release_addr = (char*) (s + beg_delta + required_size);
85 os::release_memory(release_addr, end_delta);
86 }
87
88 return (char*) (s + beg_delta);
89 }
90
91 char* ReservedSpace::reserve_and_align(const size_t reserve_size,
92 const size_t prefix_size,
93 const size_t prefix_align,
94 const size_t suffix_size,
95 const size_t suffix_align)
96 {
97 assert(reserve_size > prefix_size + suffix_size, "should not be here");
98
99 char* raw_addr = os::reserve_memory(reserve_size, NULL, prefix_align);
100 if (raw_addr == NULL) return NULL;
101
102 char* result = align_reserved_region(raw_addr, reserve_size, prefix_size,
103 prefix_align, suffix_size,
104 suffix_align);
105 if (result == NULL && !os::release_memory(raw_addr, reserve_size)) {
106 fatal("os::release_memory failed");
107 }
108
109 #ifdef ASSERT
110 if (result != NULL) {
111 const size_t raw = size_t(raw_addr);
112 const size_t res = size_t(result);
113 assert(res >= raw, "alignment decreased start addr");
114 assert(res + prefix_size + suffix_size <= raw + reserve_size,
115 "alignment increased end addr");
116 assert((res & (prefix_align - 1)) == 0, "bad alignment of prefix");
117 assert(((res + prefix_size) & (suffix_align - 1)) == 0,
118 "bad alignment of suffix");
119 }
120 #endif
121
122 return result;
123 }
124
125 // Helper method.
126 static bool failed_to_reserve_as_requested(char* base, char* requested_address,
127 const size_t size, bool special)
128 {
129 if (base == requested_address || requested_address == NULL)
130 return false; // did not fail
131
132 if (base != NULL) {
133 // Different reserve address may be acceptable in other cases
134 // but for compressed oops heap should be at requested address.
135 assert(UseCompressedOops, "currently requested address used only for compressed oops");
136 if (PrintCompressedOopsMode) {
137 tty->cr();
138 tty->print_cr("Reserved memory not at requested address: " PTR_FORMAT " vs " PTR_FORMAT, base, requested_address);
139 }
140 // OS ignored requested address. Try different address.
141 if (special) {
142 if (!os::release_memory_special(base, size)) {
143 fatal("os::release_memory_special failed");
144 }
145 } else {
146 if (!os::release_memory(base, size)) {
147 fatal("os::release_memory failed");
148 }
149 }
150 }
151 return true;
152 }
153
154 ReservedSpace::ReservedSpace(const size_t prefix_size,
155 const size_t prefix_align,
156 const size_t suffix_size,
157 const size_t suffix_align,
158 char* requested_address,
159 const size_t noaccess_prefix)
160 {
161 assert(prefix_size != 0, "sanity");
162 assert(prefix_align != 0, "sanity");
163 assert(suffix_size != 0, "sanity");
164 assert(suffix_align != 0, "sanity");
165 assert((prefix_size & (prefix_align - 1)) == 0,
166 "prefix_size not divisible by prefix_align");
167 assert((suffix_size & (suffix_align - 1)) == 0,
168 "suffix_size not divisible by suffix_align");
169 assert((suffix_align & (prefix_align - 1)) == 0,
170 "suffix_align not divisible by prefix_align");
171
172 // Assert that if noaccess_prefix is used, it is the same as prefix_align.
173 assert(noaccess_prefix == 0 ||
174 noaccess_prefix == prefix_align, "noaccess prefix wrong");
175
176 // Add in noaccess_prefix to prefix_size;
177 const size_t adjusted_prefix_size = prefix_size + noaccess_prefix;
178 const size_t size = adjusted_prefix_size + suffix_size;
179
180 // On systems where the entire region has to be reserved and committed up
181 // front, the compound alignment normally done by this method is unnecessary.
182 const bool try_reserve_special = UseLargePages &&
183 prefix_align == os::large_page_size();
184 if (!os::can_commit_large_page_memory() && try_reserve_special) {
185 initialize(size, prefix_align, true, requested_address, noaccess_prefix,
186 false);
187 return;
188 }
189
190 _base = NULL;
191 _size = 0;
192 _alignment = 0;
193 _special = false;
194 _noaccess_prefix = 0;
195 _executable = false;
196
197 // Optimistically try to reserve the exact size needed.
198 char* addr;
199 if (requested_address != 0) {
200 requested_address -= noaccess_prefix; // adjust address
201 assert(requested_address != NULL, "huge noaccess prefix?");
202 addr = os::attempt_reserve_memory_at(size, requested_address);
203 if (failed_to_reserve_as_requested(addr, requested_address, size, false)) {
204 // OS ignored requested address. Try different address.
205 addr = NULL;
206 }
207 } else {
208 addr = os::reserve_memory(size, NULL, prefix_align);
209 }
210 if (addr == NULL) return;
211
212 // Check whether the result has the needed alignment (unlikely unless
213 // prefix_align < suffix_align).
214 const size_t ofs = (size_t(addr) + adjusted_prefix_size) & (suffix_align - 1);
215 if (ofs != 0) {
216 // Wrong alignment. Release, allocate more space and do manual alignment.
217 //
218 // On most operating systems, another allocation with a somewhat larger size
219 // will return an address "close to" that of the previous allocation. The
220 // result is often the same address (if the kernel hands out virtual
221 // addresses from low to high), or an address that is offset by the increase
222 // in size. Exploit that to minimize the amount of extra space requested.
223 if (!os::release_memory(addr, size)) {
224 fatal("os::release_memory failed");
225 }
226
227 const size_t extra = MAX2(ofs, suffix_align - ofs);
228 addr = reserve_and_align(size + extra, adjusted_prefix_size, prefix_align,
229 suffix_size, suffix_align);
230 if (addr == NULL) {
231 // Try an even larger region. If this fails, address space is exhausted.
232 addr = reserve_and_align(size + suffix_align, adjusted_prefix_size,
233 prefix_align, suffix_size, suffix_align);
234 }
235
236 if (requested_address != 0 &&
237 failed_to_reserve_as_requested(addr, requested_address, size, false)) {
238 // As a result of the alignment constraints, the allocated addr differs
239 // from the requested address. Return back to the caller who can
240 // take remedial action (like try again without a requested address).
241 assert(_base == NULL, "should be");
242 return;
243 }
244 }
245
246 _base = addr;
247 _size = size;
248 _alignment = prefix_align;
249 _noaccess_prefix = noaccess_prefix;
250 }
251
252 void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
253 char* requested_address,
254 const size_t noaccess_prefix,
255 bool executable) {
256 const size_t granularity = os::vm_allocation_granularity();
257 assert((size & (granularity - 1)) == 0,
258 "size not aligned to os::vm_allocation_granularity()");
259 assert((alignment & (granularity - 1)) == 0,
260 "alignment not aligned to os::vm_allocation_granularity()");
261 assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
262 "not a power of 2");
263
264 alignment = MAX2(alignment, (size_t)os::vm_page_size());
265
266 // Assert that if noaccess_prefix is used, it is the same as alignment.
267 assert(noaccess_prefix == 0 ||
268 noaccess_prefix == alignment, "noaccess prefix wrong");
269
270 _base = NULL;
271 _size = 0;
272 _special = false;
273 _executable = executable;
274 _alignment = 0;
275 _noaccess_prefix = 0;
276 if (size == 0) {
277 return;
278 }
279
280 // If OS doesn't support demand paging for large page memory, we need
281 // to use reserve_memory_special() to reserve and pin the entire region.
282 bool special = large && !os::can_commit_large_page_memory();
283 char* base = NULL;
284
285 if (requested_address != 0) {
286 requested_address -= noaccess_prefix; // adjust requested address
287 assert(requested_address != NULL, "huge noaccess prefix?");
288 }
289
290 if (special) {
291
292 base = os::reserve_memory_special(size, requested_address, executable);
293
294 if (base != NULL) {
295 if (failed_to_reserve_as_requested(base, requested_address, size, true)) {
296 // OS ignored requested address. Try different address.
297 return;
298 }
299 // Check alignment constraints
300 assert((uintptr_t) base % alignment == 0,
301 "Large pages returned a non-aligned address");
302 _special = true;
303 } else {
304 // failed; try to reserve regular memory below
305 if (UseLargePages && (!FLAG_IS_DEFAULT(UseLargePages) ||
306 !FLAG_IS_DEFAULT(LargePageSizeInBytes))) {
307 if (PrintCompressedOopsMode) {
308 tty->cr();
309 tty->print_cr("Reserve regular memory without large pages.");
310 }
311 }
312 }
313 }
314
315 if (base == NULL) {
316 // Optimistically assume that the OSes returns an aligned base pointer.
317 // When reserving a large address range, most OSes seem to align to at
318 // least 64K.
319
320 // If the memory was requested at a particular address, use
321 // os::attempt_reserve_memory_at() to avoid over mapping something
322 // important. If available space is not detected, return NULL.
323
324 if (requested_address != 0) {
325 base = os::attempt_reserve_memory_at(size, requested_address);
326 if (failed_to_reserve_as_requested(base, requested_address, size, false)) {
327 // OS ignored requested address. Try different address.
328 base = NULL;
329 }
330 } else {
331 base = os::reserve_memory(size, NULL, alignment);
332 }
333
334 if (base == NULL) return;
335
336 // Check alignment constraints
337 if ((((size_t)base + noaccess_prefix) & (alignment - 1)) != 0) {
338 // Base not aligned, retry
339 if (!os::release_memory(base, size)) fatal("os::release_memory failed");
340 // Reserve size large enough to do manual alignment and
341 // increase size to a multiple of the desired alignment
342 size = align_size_up(size, alignment);
343 size_t extra_size = size + alignment;
344 do {
345 char* extra_base = os::reserve_memory(extra_size, NULL, alignment);
346 if (extra_base == NULL) return;
347 // Do manual alignement
348 base = (char*) align_size_up((uintptr_t) extra_base, alignment);
349 assert(base >= extra_base, "just checking");
350 // Re-reserve the region at the aligned base address.
351 os::release_memory(extra_base, extra_size);
352 base = os::reserve_memory(size, base);
353 } while (base == NULL);
354
355 if (requested_address != 0 &&
356 failed_to_reserve_as_requested(base, requested_address, size, false)) {
357 // As a result of the alignment constraints, the allocated base differs
358 // from the requested address. Return back to the caller who can
359 // take remedial action (like try again without a requested address).
360 assert(_base == NULL, "should be");
361 return;
362 }
363 }
364 }
365 // Done
366 _base = base;
367 _size = size;
368 _alignment = alignment;
369 _noaccess_prefix = noaccess_prefix;
370
371 // Assert that if noaccess_prefix is used, it is the same as alignment.
372 assert(noaccess_prefix == 0 ||
373 noaccess_prefix == _alignment, "noaccess prefix wrong");
374
375 assert(markOopDesc::encode_pointer_as_mark(_base)->decode_pointer() == _base,
376 "area must be distinguisable from marks for mark-sweep");
377 assert(markOopDesc::encode_pointer_as_mark(&_base[size])->decode_pointer() == &_base[size],
378 "area must be distinguisable from marks for mark-sweep");
379 }
380
381
382 ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment,
383 bool special, bool executable) {
384 assert((size % os::vm_allocation_granularity()) == 0,
385 "size not allocation aligned");
386 _base = base;
387 _size = size;
388 _alignment = alignment;
389 _noaccess_prefix = 0;
390 _special = special;
391 _executable = executable;
392 }
393
394
395 ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment,
396 bool split, bool realloc) {
397 assert(partition_size <= size(), "partition failed");
398 if (split) {
399 os::split_reserved_memory(base(), size(), partition_size, realloc);
400 }
401 ReservedSpace result(base(), partition_size, alignment, special(),
402 executable());
403 return result;
404 }
405
406
407 ReservedSpace
408 ReservedSpace::last_part(size_t partition_size, size_t alignment) {
409 assert(partition_size <= size(), "partition failed");
410 ReservedSpace result(base() + partition_size, size() - partition_size,
411 alignment, special(), executable());
412 return result;
413 }
414
415
416 size_t ReservedSpace::page_align_size_up(size_t size) {
417 return align_size_up(size, os::vm_page_size());
418 }
419
420
421 size_t ReservedSpace::page_align_size_down(size_t size) {
422 return align_size_down(size, os::vm_page_size());
423 }
424
425
426 size_t ReservedSpace::allocation_align_size_up(size_t size) {
427 return align_size_up(size, os::vm_allocation_granularity());
428 }
429
430
431 size_t ReservedSpace::allocation_align_size_down(size_t size) {
432 return align_size_down(size, os::vm_allocation_granularity());
433 }
434
435
436 void ReservedSpace::release() {
437 if (is_reserved()) {
438 char *real_base = _base - _noaccess_prefix;
439 const size_t real_size = _size + _noaccess_prefix;
440 if (special()) {
441 os::release_memory_special(real_base, real_size);
442 } else{
443 os::release_memory(real_base, real_size);
444 }
445 _base = NULL;
446 _size = 0;
447 _noaccess_prefix = 0;
448 _special = false;
449 _executable = false;
450 }
451 }
452
453 void ReservedSpace::protect_noaccess_prefix(const size_t size) {
454 assert( (_noaccess_prefix != 0) == (UseCompressedOops && _base != NULL &&
455 (size_t(_base + _size) > OopEncodingHeapMax) &&
456 Universe::narrow_oop_use_implicit_null_checks()),
457 "noaccess_prefix should be used only with non zero based compressed oops");
458
459 // If there is no noaccess prefix, return.
460 if (_noaccess_prefix == 0) return;
461
462 assert(_noaccess_prefix >= (size_t)os::vm_page_size(),
463 "must be at least page size big");
464
465 // Protect memory at the base of the allocated region.
466 // If special, the page was committed (only matters on windows)
467 if (!os::protect_memory(_base, _noaccess_prefix, os::MEM_PROT_NONE,
468 _special)) {
469 fatal("cannot protect protection page");
470 }
471 if (PrintCompressedOopsMode) {
472 tty->cr();
473 tty->print_cr("Protected page at the reserved heap base: " PTR_FORMAT " / " INTX_FORMAT " bytes", _base, _noaccess_prefix);
474 }
475
476 _base += _noaccess_prefix;
477 _size -= _noaccess_prefix;
478 assert((size == _size) && ((uintptr_t)_base % _alignment == 0),
479 "must be exactly of required size and alignment");
480 }
481
482 ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment,
483 bool large, char* requested_address) :
484 ReservedSpace(size, alignment, large,
485 requested_address,
486 (UseCompressedOops && (Universe::narrow_oop_base() != NULL) &&
487 Universe::narrow_oop_use_implicit_null_checks()) ?
488 lcm(os::vm_page_size(), alignment) : 0) {
489 // Only reserved space for the java heap should have a noaccess_prefix
490 // if using compressed oops.
491 protect_noaccess_prefix(size);
492 }
493
494 ReservedHeapSpace::ReservedHeapSpace(const size_t prefix_size,
495 const size_t prefix_align,
496 const size_t suffix_size,
497 const size_t suffix_align,
498 char* requested_address) :
499 ReservedSpace(prefix_size, prefix_align, suffix_size, suffix_align,
500 requested_address,
501 (UseCompressedOops && (Universe::narrow_oop_base() != NULL) &&
502 Universe::narrow_oop_use_implicit_null_checks()) ?
503 lcm(os::vm_page_size(), prefix_align) : 0) {
504 protect_noaccess_prefix(prefix_size+suffix_size);
505 }
506
507 // Reserve space for code segment. Same as Java heap only we mark this as
508 // executable.
509 ReservedCodeSpace::ReservedCodeSpace(size_t r_size,
510 size_t rs_align,
511 bool large) :
512 ReservedSpace(r_size, rs_align, large, /*executable*/ true) {
513 }
514
515 // VirtualSpace
516
517 VirtualSpace::VirtualSpace() {
518 _low_boundary = NULL;
519 _high_boundary = NULL;
520 _low = NULL;
521 _high = NULL;
522 _lower_high = NULL;
523 _middle_high = NULL;
524 _upper_high = NULL;
525 _lower_high_boundary = NULL;
526 _middle_high_boundary = NULL;
527 _upper_high_boundary = NULL;
528 _lower_alignment = 0;
529 _middle_alignment = 0;
530 _upper_alignment = 0;
531 _special = false;
532 _executable = false;
533 }
534
535
536 bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) {
537 if(!rs.is_reserved()) return false; // allocation failed.
538 assert(_low_boundary == NULL, "VirtualSpace already initialized");
539 _low_boundary = rs.base();
540 _high_boundary = low_boundary() + rs.size();
541
542 _low = low_boundary();
543 _high = low();
544
545 _special = rs.special();
546 _executable = rs.executable();
547
548 // When a VirtualSpace begins life at a large size, make all future expansion
549 // and shrinking occur aligned to a granularity of large pages. This avoids
550 // fragmentation of physical addresses that inhibits the use of large pages
551 // by the OS virtual memory system. Empirically, we see that with a 4MB
552 // page size, the only spaces that get handled this way are codecache and
553 // the heap itself, both of which provide a substantial performance
554 // boost in many benchmarks when covered by large pages.
555 //
556 // No attempt is made to force large page alignment at the very top and
557 // bottom of the space if they are not aligned so already.
558 _lower_alignment = os::vm_page_size();
559 _middle_alignment = os::page_size_for_region(rs.size(), rs.size(), 1);
560 _upper_alignment = os::vm_page_size();
561
562 // End of each region
563 _lower_high_boundary = (char*) round_to((intptr_t) low_boundary(), middle_alignment());
564 _middle_high_boundary = (char*) round_down((intptr_t) high_boundary(), middle_alignment());
565 _upper_high_boundary = high_boundary();
566
567 // High address of each region
568 _lower_high = low_boundary();
569 _middle_high = lower_high_boundary();
570 _upper_high = middle_high_boundary();
571
572 // commit to initial size
573 if (committed_size > 0) {
574 if (!expand_by(committed_size)) {
575 return false;
576 }
577 }
578 return true;
579 }
580
581
582 VirtualSpace::~VirtualSpace() {
583 release();
584 }
585
586
587 void VirtualSpace::release() {
588 // This does not release memory it never reserved.
589 // Caller must release via rs.release();
590 _low_boundary = NULL;
591 _high_boundary = NULL;
592 _low = NULL;
593 _high = NULL;
594 _lower_high = NULL;
595 _middle_high = NULL;
596 _upper_high = NULL;
597 _lower_high_boundary = NULL;
598 _middle_high_boundary = NULL;
599 _upper_high_boundary = NULL;
600 _lower_alignment = 0;
601 _middle_alignment = 0;
602 _upper_alignment = 0;
603 _special = false;
604 _executable = false;
605 }
606
607
608 size_t VirtualSpace::committed_size() const {
609 return pointer_delta(high(), low(), sizeof(char));
610 }
611
612
613 size_t VirtualSpace::reserved_size() const {
614 return pointer_delta(high_boundary(), low_boundary(), sizeof(char));
615 }
616
617
618 size_t VirtualSpace::uncommitted_size() const {
619 return reserved_size() - committed_size();
620 }
621
622
623 bool VirtualSpace::contains(const void* p) const {
624 return low() <= (const char*) p && (const char*) p < high();
625 }
626
627 /*
628 First we need to determine if a particular virtual space is using large
629 pages. This is done at the initialize function and only virtual spaces
630 that are larger than LargePageSizeInBytes use large pages. Once we
631 have determined this, all expand_by and shrink_by calls must grow and
632 shrink by large page size chunks. If a particular request
633 is within the current large page, the call to commit and uncommit memory
634 can be ignored. In the case that the low and high boundaries of this
635 space is not large page aligned, the pages leading to the first large
636 page address and the pages after the last large page address must be
637 allocated with default pages.
638 */
639 bool VirtualSpace::expand_by(size_t bytes, bool pre_touch) {
640 if (uncommitted_size() < bytes) return false;
641
642 if (special()) {
643 // don't commit memory if the entire space is pinned in memory
644 _high += bytes;
645 return true;
646 }
647
648 char* previous_high = high();
649 char* unaligned_new_high = high() + bytes;
650 assert(unaligned_new_high <= high_boundary(),
651 "cannot expand by more than upper boundary");
652
653 // Calculate where the new high for each of the regions should be. If
654 // the low_boundary() and high_boundary() are LargePageSizeInBytes aligned
655 // then the unaligned lower and upper new highs would be the
656 // lower_high() and upper_high() respectively.
657 char* unaligned_lower_new_high =
658 MIN2(unaligned_new_high, lower_high_boundary());
659 char* unaligned_middle_new_high =
660 MIN2(unaligned_new_high, middle_high_boundary());
661 char* unaligned_upper_new_high =
662 MIN2(unaligned_new_high, upper_high_boundary());
663
664 // Align the new highs based on the regions alignment. lower and upper
665 // alignment will always be default page size. middle alignment will be
666 // LargePageSizeInBytes if the actual size of the virtual space is in
667 // fact larger than LargePageSizeInBytes.
668 char* aligned_lower_new_high =
669 (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment());
670 char* aligned_middle_new_high =
671 (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment());
672 char* aligned_upper_new_high =
673 (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment());
674
675 // Determine which regions need to grow in this expand_by call.
676 // If you are growing in the lower region, high() must be in that
677 // region so calcuate the size based on high(). For the middle and
678 // upper regions, determine the starting point of growth based on the
679 // location of high(). By getting the MAX of the region's low address
680 // (or the prevoius region's high address) and high(), we can tell if it
681 // is an intra or inter region growth.
682 size_t lower_needs = 0;
683 if (aligned_lower_new_high > lower_high()) {
684 lower_needs =
685 pointer_delta(aligned_lower_new_high, lower_high(), sizeof(char));
686 }
687 size_t middle_needs = 0;
688 if (aligned_middle_new_high > middle_high()) {
689 middle_needs =
690 pointer_delta(aligned_middle_new_high, middle_high(), sizeof(char));
691 }
692 size_t upper_needs = 0;
693 if (aligned_upper_new_high > upper_high()) {
694 upper_needs =
695 pointer_delta(aligned_upper_new_high, upper_high(), sizeof(char));
696 }
697
698 // Check contiguity.
699 assert(low_boundary() <= lower_high() &&
700 lower_high() <= lower_high_boundary(),
701 "high address must be contained within the region");
702 assert(lower_high_boundary() <= middle_high() &&
703 middle_high() <= middle_high_boundary(),
704 "high address must be contained within the region");
705 assert(middle_high_boundary() <= upper_high() &&
706 upper_high() <= upper_high_boundary(),
707 "high address must be contained within the region");
708
709 // Commit regions
710 if (lower_needs > 0) {
711 assert(low_boundary() <= lower_high() &&
712 lower_high() + lower_needs <= lower_high_boundary(),
713 "must not expand beyond region");
714 if (!os::commit_memory(lower_high(), lower_needs, _executable)) {
715 debug_only(warning("os::commit_memory failed"));
716 return false;
717 } else {
718 _lower_high += lower_needs;
719 }
720 }
721 if (middle_needs > 0) {
722 assert(lower_high_boundary() <= middle_high() &&
723 middle_high() + middle_needs <= middle_high_boundary(),
724 "must not expand beyond region");
725 if (!os::commit_memory(middle_high(), middle_needs, middle_alignment(),
726 _executable)) {
727 debug_only(warning("os::commit_memory failed"));
728 return false;
729 }
730 _middle_high += middle_needs;
731 }
732 if (upper_needs > 0) {
733 assert(middle_high_boundary() <= upper_high() &&
734 upper_high() + upper_needs <= upper_high_boundary(),
735 "must not expand beyond region");
736 if (!os::commit_memory(upper_high(), upper_needs, _executable)) {
737 debug_only(warning("os::commit_memory failed"));
738 return false;
739 } else {
740 _upper_high += upper_needs;
741 }
742 }
743
744 if (pre_touch || AlwaysPreTouch) {
745 int vm_ps = os::vm_page_size();
746 for (char* curr = previous_high;
747 curr < unaligned_new_high;
748 curr += vm_ps) {
749 // Note the use of a write here; originally we tried just a read, but
750 // since the value read was unused, the optimizer removed the read.
751 // If we ever have a concurrent touchahead thread, we'll want to use
752 // a read, to avoid the potential of overwriting data (if a mutator
753 // thread beats the touchahead thread to a page). There are various
754 // ways of making sure this read is not optimized away: for example,
755 // generating the code for a read procedure at runtime.
756 *curr = 0;
757 }
758 }
759
760 _high += bytes;
761 return true;
762 }
763
764 // A page is uncommitted if the contents of the entire page is deemed unusable.
765 // Continue to decrement the high() pointer until it reaches a page boundary
766 // in which case that particular page can now be uncommitted.
767 void VirtualSpace::shrink_by(size_t size) {
768 if (committed_size() < size)
769 fatal("Cannot shrink virtual space to negative size");
770
771 if (special()) {
772 // don't uncommit if the entire space is pinned in memory
773 _high -= size;
774 return;
775 }
776
777 char* unaligned_new_high = high() - size;
778 assert(unaligned_new_high >= low_boundary(), "cannot shrink past lower boundary");
779
780 // Calculate new unaligned address
781 char* unaligned_upper_new_high =
782 MAX2(unaligned_new_high, middle_high_boundary());
783 char* unaligned_middle_new_high =
784 MAX2(unaligned_new_high, lower_high_boundary());
785 char* unaligned_lower_new_high =
786 MAX2(unaligned_new_high, low_boundary());
787
788 // Align address to region's alignment
789 char* aligned_upper_new_high =
790 (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment());
791 char* aligned_middle_new_high =
792 (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment());
793 char* aligned_lower_new_high =
794 (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment());
795
796 // Determine which regions need to shrink
797 size_t upper_needs = 0;
798 if (aligned_upper_new_high < upper_high()) {
799 upper_needs =
800 pointer_delta(upper_high(), aligned_upper_new_high, sizeof(char));
801 }
802 size_t middle_needs = 0;
803 if (aligned_middle_new_high < middle_high()) {
804 middle_needs =
805 pointer_delta(middle_high(), aligned_middle_new_high, sizeof(char));
806 }
807 size_t lower_needs = 0;
808 if (aligned_lower_new_high < lower_high()) {
809 lower_needs =
810 pointer_delta(lower_high(), aligned_lower_new_high, sizeof(char));
811 }
812
813 // Check contiguity.
814 assert(middle_high_boundary() <= upper_high() &&
815 upper_high() <= upper_high_boundary(),
816 "high address must be contained within the region");
817 assert(lower_high_boundary() <= middle_high() &&
818 middle_high() <= middle_high_boundary(),
819 "high address must be contained within the region");
820 assert(low_boundary() <= lower_high() &&
821 lower_high() <= lower_high_boundary(),
822 "high address must be contained within the region");
823
824 // Uncommit
825 if (upper_needs > 0) {
826 assert(middle_high_boundary() <= aligned_upper_new_high &&
827 aligned_upper_new_high + upper_needs <= upper_high_boundary(),
828 "must not shrink beyond region");
829 if (!os::uncommit_memory(aligned_upper_new_high, upper_needs)) {
830 debug_only(warning("os::uncommit_memory failed"));
831 return;
832 } else {
833 _upper_high -= upper_needs;
834 }
835 }
836 if (middle_needs > 0) {
837 assert(lower_high_boundary() <= aligned_middle_new_high &&
838 aligned_middle_new_high + middle_needs <= middle_high_boundary(),
839 "must not shrink beyond region");
840 if (!os::uncommit_memory(aligned_middle_new_high, middle_needs)) {
841 debug_only(warning("os::uncommit_memory failed"));
842 return;
843 } else {
844 _middle_high -= middle_needs;
845 }
846 }
847 if (lower_needs > 0) {
848 assert(low_boundary() <= aligned_lower_new_high &&
849 aligned_lower_new_high + lower_needs <= lower_high_boundary(),
850 "must not shrink beyond region");
851 if (!os::uncommit_memory(aligned_lower_new_high, lower_needs)) {
852 debug_only(warning("os::uncommit_memory failed"));
853 return;
854 } else {
855 _lower_high -= lower_needs;
856 }
857 }
858
859 _high -= size;
860 }
861
862 #ifndef PRODUCT
863 void VirtualSpace::check_for_contiguity() {
864 // Check contiguity.
865 assert(low_boundary() <= lower_high() &&
866 lower_high() <= lower_high_boundary(),
867 "high address must be contained within the region");
868 assert(lower_high_boundary() <= middle_high() &&
869 middle_high() <= middle_high_boundary(),
870 "high address must be contained within the region");
871 assert(middle_high_boundary() <= upper_high() &&
872 upper_high() <= upper_high_boundary(),
873 "high address must be contained within the region");
874 assert(low() >= low_boundary(), "low");
875 assert(low_boundary() <= lower_high_boundary(), "lower high boundary");
876 assert(upper_high_boundary() <= high_boundary(), "upper high boundary");
877 assert(high() <= upper_high(), "upper high");
878 }
879
880 void VirtualSpace::print() {
881 tty->print ("Virtual space:");
882 if (special()) tty->print(" (pinned in memory)");
883 tty->cr();
884 tty->print_cr(" - committed: %ld", committed_size());
885 tty->print_cr(" - reserved: %ld", reserved_size());
886 tty->print_cr(" - [low, high]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]", low(), high());
887 tty->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]", low_boundary(), high_boundary());
888 }
889
890 #endif