1 /*
2 * Copyright (c) 1997, 2012, 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 #include "services/memTracker.hpp"
30 #ifdef TARGET_OS_FAMILY_linux
31 # include "os_linux.inline.hpp"
32 #endif
33 #ifdef TARGET_OS_FAMILY_solaris
34 # include "os_solaris.inline.hpp"
35 #endif
36 #ifdef TARGET_OS_FAMILY_windows
37 # include "os_windows.inline.hpp"
38 #endif
39 #ifdef TARGET_OS_FAMILY_bsd
40 # include "os_bsd.inline.hpp"
41 #endif
42
43
44 // ReservedSpace
45 ReservedSpace::ReservedSpace(size_t size) {
46 initialize(size, 0, false, NULL, 0, false);
47 }
48
49 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
50 bool large,
51 char* requested_address,
52 const size_t noaccess_prefix) {
53 initialize(size+noaccess_prefix, alignment, large, requested_address,
54 noaccess_prefix, false);
55 }
56
57 ReservedSpace::ReservedSpace(size_t size, size_t alignment,
58 bool large,
59 bool executable) {
60 initialize(size, alignment, large, NULL, 0, executable);
61 }
62
63 char *
64 ReservedSpace::align_reserved_region(char* addr, const size_t len,
65 const size_t prefix_size,
66 const size_t prefix_align,
67 const size_t suffix_size,
68 const size_t suffix_align)
69 {
70 assert(addr != NULL, "sanity");
71 const size_t required_size = prefix_size + suffix_size;
72 assert(len >= required_size, "len too small");
73
74 const size_t s = size_t(addr);
75 const size_t beg_ofs = (s + prefix_size) & (suffix_align - 1);
76 const size_t beg_delta = beg_ofs == 0 ? 0 : suffix_align - beg_ofs;
77
78 if (len < beg_delta + required_size) {
79 return NULL; // Cannot do proper alignment.
80 }
81 const size_t end_delta = len - (beg_delta + required_size);
82
83 if (beg_delta != 0) {
84 os::release_memory(addr, beg_delta);
85 }
86
87 if (end_delta != 0) {
88 char* release_addr = (char*) (s + beg_delta + required_size);
89 os::release_memory(release_addr, end_delta);
90 }
91
92 return (char*) (s + beg_delta);
93 }
94
95 char* ReservedSpace::reserve_and_align(const size_t reserve_size,
96 const size_t prefix_size,
97 const size_t prefix_align,
98 const size_t suffix_size,
99 const size_t suffix_align)
100 {
101 assert(reserve_size > prefix_size + suffix_size, "should not be here");
102
103 char* raw_addr = os::reserve_memory(reserve_size, NULL, prefix_align);
104 if (raw_addr == NULL) return NULL;
105
106 char* result = align_reserved_region(raw_addr, reserve_size, prefix_size,
107 prefix_align, suffix_size,
108 suffix_align);
109 if (result == NULL && !os::release_memory(raw_addr, reserve_size)) {
110 fatal("os::release_memory failed");
111 }
112
113 #ifdef ASSERT
114 if (result != NULL) {
115 const size_t raw = size_t(raw_addr);
116 const size_t res = size_t(result);
117 assert(res >= raw, "alignment decreased start addr");
118 assert(res + prefix_size + suffix_size <= raw + reserve_size,
119 "alignment increased end addr");
120 assert((res & (prefix_align - 1)) == 0, "bad alignment of prefix");
121 assert(((res + prefix_size) & (suffix_align - 1)) == 0,
122 "bad alignment of suffix");
123 }
124 #endif
125
126 return result;
127 }
128
129 // Helper method.
130 static bool failed_to_reserve_as_requested(char* base, char* requested_address,
131 const size_t size, bool special)
132 {
133 if (base == requested_address || requested_address == NULL)
134 return false; // did not fail
135
136 if (base != NULL) {
137 // Different reserve address may be acceptable in other cases
138 // but for compressed oops heap should be at requested address.
139 assert(UseCompressedOops, "currently requested address used only for compressed oops");
140 if (PrintCompressedOopsMode) {
141 tty->cr();
142 tty->print_cr("Reserved memory not at requested address: " PTR_FORMAT " vs " PTR_FORMAT, base, requested_address);
143 }
144 // OS ignored requested address. Try different address.
145 if (special) {
146 if (!os::release_memory_special(base, size)) {
147 fatal("os::release_memory_special failed");
148 }
149 } else {
150 if (!os::release_memory(base, size)) {
151 fatal("os::release_memory failed");
152 }
153 }
154 }
155 return true;
156 }
157
158 ReservedSpace::ReservedSpace(const size_t suffix_size,
159 const size_t suffix_align,
160 char* requested_address,
161 const size_t noaccess_prefix)
162 {
163 assert(suffix_size != 0, "sanity");
164 assert(suffix_align != 0, "sanity");
165 assert((suffix_size & (suffix_align - 1)) == 0,
166 "suffix_size not divisible by suffix_align");
167
168 // Assert that if noaccess_prefix is used, it is the same as prefix_align.
169 // Add in noaccess_prefix to prefix
170 const size_t adjusted_prefix_size = noaccess_prefix;
171 const size_t size = adjusted_prefix_size + suffix_size;
172
173 // On systems where the entire region has to be reserved and committed up
174 // front, the compound alignment normally done by this method is unnecessary.
175 const bool try_reserve_special = UseLargePages &&
176 suffix_align == os::large_page_size();
177 if (!os::can_commit_large_page_memory() && try_reserve_special) {
178 initialize(size, suffix_align, true, requested_address, noaccess_prefix,
179 false);
180 return;
181 }
182
183 _base = NULL;
184 _size = 0;
185 _alignment = 0;
186 _special = false;
187 _noaccess_prefix = 0;
188 _executable = false;
189
190 // Optimistically try to reserve the exact size needed.
191 char* addr;
192 if (requested_address != 0) {
193 requested_address -= noaccess_prefix; // adjust address
194 assert(requested_address != NULL, "huge noaccess prefix?");
195 addr = os::attempt_reserve_memory_at(size, requested_address);
196 if (failed_to_reserve_as_requested(addr, requested_address, size, false)) {
197 // OS ignored requested address. Try different address.
198 addr = NULL;
199 }
200 } else {
201 addr = os::reserve_memory(size, NULL, suffix_align);
202 }
203 if (addr == NULL) return;
204
205 // Check whether the result has the needed alignment
206 const size_t ofs = (size_t(addr) + adjusted_prefix_size) & (suffix_align - 1);
207 if (ofs != 0) {
208 // Wrong alignment. Release, allocate more space and do manual alignment.
209 //
210 // On most operating systems, another allocation with a somewhat larger size
211 // will return an address "close to" that of the previous allocation. The
212 // result is often the same address (if the kernel hands out virtual
213 // addresses from low to high), or an address that is offset by the increase
214 // in size. Exploit that to minimize the amount of extra space requested.
215 if (!os::release_memory(addr, size)) {
216 fatal("os::release_memory failed");
217 }
218
219 const size_t extra = MAX2(ofs, suffix_align - ofs);
220 addr = reserve_and_align(size + extra, adjusted_prefix_size, suffix_align,
221 suffix_size, suffix_align);
222 if (addr == NULL) {
223 // Try an even larger region. If this fails, address space is exhausted.
224 addr = reserve_and_align(size + suffix_align, adjusted_prefix_size,
225 suffix_align, suffix_size, suffix_align);
226 }
227
228 if (requested_address != 0 &&
229 failed_to_reserve_as_requested(addr, requested_address, size, false)) {
230 // As a result of the alignment constraints, the allocated addr differs
231 // from the requested address. Return back to the caller who can
232 // take remedial action (like try again without a requested address).
233 assert(_base == NULL, "should be");
234 return;
235 }
236 }
237
238 _base = addr;
239 _size = size;
240 _alignment = suffix_align;
241 _noaccess_prefix = noaccess_prefix;
242 }
243
244 void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
245 char* requested_address,
246 const size_t noaccess_prefix,
247 bool executable) {
248 const size_t granularity = os::vm_allocation_granularity();
249 assert((size & (granularity - 1)) == 0,
250 "size not aligned to os::vm_allocation_granularity()");
251 assert((alignment & (granularity - 1)) == 0,
252 "alignment not aligned to os::vm_allocation_granularity()");
253 assert(alignment == 0 || is_power_of_2((intptr_t)alignment),
254 "not a power of 2");
255
256 alignment = MAX2(alignment, (size_t)os::vm_page_size());
257
258 // Assert that if noaccess_prefix is used, it is the same as alignment.
259 assert(noaccess_prefix == 0 ||
260 noaccess_prefix == alignment, "noaccess prefix wrong");
261
262 _base = NULL;
263 _size = 0;
264 _special = false;
265 _executable = executable;
266 _alignment = 0;
267 _noaccess_prefix = 0;
268 if (size == 0) {
269 return;
270 }
271
272 // If OS doesn't support demand paging for large page memory, we need
273 // to use reserve_memory_special() to reserve and pin the entire region.
274 bool special = large && !os::can_commit_large_page_memory();
275 char* base = NULL;
276
277 if (requested_address != 0) {
278 requested_address -= noaccess_prefix; // adjust requested address
279 assert(requested_address != NULL, "huge noaccess prefix?");
280 }
281
282 if (special) {
283
284 base = os::reserve_memory_special(size, requested_address, executable);
285
286 if (base != NULL) {
287 if (failed_to_reserve_as_requested(base, requested_address, size, true)) {
288 // OS ignored requested address. Try different address.
289 return;
290 }
291 // Check alignment constraints
292 assert((uintptr_t) base % alignment == 0,
293 "Large pages returned a non-aligned address");
294 _special = true;
295 } else {
296 // failed; try to reserve regular memory below
297 if (UseLargePages && (!FLAG_IS_DEFAULT(UseLargePages) ||
298 !FLAG_IS_DEFAULT(LargePageSizeInBytes))) {
299 if (PrintCompressedOopsMode) {
300 tty->cr();
301 tty->print_cr("Reserve regular memory without large pages.");
302 }
303 }
304 }
305 }
306
307 if (base == NULL) {
308 // Optimistically assume that the OSes returns an aligned base pointer.
309 // When reserving a large address range, most OSes seem to align to at
310 // least 64K.
311
312 // If the memory was requested at a particular address, use
313 // os::attempt_reserve_memory_at() to avoid over mapping something
314 // important. If available space is not detected, return NULL.
315
316 if (requested_address != 0) {
317 base = os::attempt_reserve_memory_at(size, requested_address);
318 if (failed_to_reserve_as_requested(base, requested_address, size, false)) {
319 // OS ignored requested address. Try different address.
320 base = NULL;
321 }
322 } else {
323 base = os::reserve_memory(size, NULL, alignment);
324 }
325
326 if (base == NULL) return;
327
328 // Check alignment constraints
329 if ((((size_t)base + noaccess_prefix) & (alignment - 1)) != 0) {
330 // Base not aligned, retry
331 if (!os::release_memory(base, size)) fatal("os::release_memory failed");
332 // Make sure that size is aligned
333 size = align_size_up(size, alignment);
334 base = os::reserve_memory_aligned(size, alignment);
335
336 if (requested_address != 0 &&
337 failed_to_reserve_as_requested(base, requested_address, size, false)) {
338 // As a result of the alignment constraints, the allocated base differs
339 // from the requested address. Return back to the caller who can
340 // take remedial action (like try again without a requested address).
341 assert(_base == NULL, "should be");
342 return;
343 }
344 }
345 }
346 // Done
347 _base = base;
348 _size = size;
349 _alignment = alignment;
350 _noaccess_prefix = noaccess_prefix;
351
352 // Assert that if noaccess_prefix is used, it is the same as alignment.
353 assert(noaccess_prefix == 0 ||
354 noaccess_prefix == _alignment, "noaccess prefix wrong");
355
356 assert(markOopDesc::encode_pointer_as_mark(_base)->decode_pointer() == _base,
357 "area must be distinguisable from marks for mark-sweep");
358 assert(markOopDesc::encode_pointer_as_mark(&_base[size])->decode_pointer() == &_base[size],
359 "area must be distinguisable from marks for mark-sweep");
360 }
361
362
363 ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment,
364 bool special, bool executable) {
365 assert((size % os::vm_allocation_granularity()) == 0,
366 "size not allocation aligned");
367 _base = base;
368 _size = size;
369 _alignment = alignment;
370 _noaccess_prefix = 0;
371 _special = special;
372 _executable = executable;
373 }
374
375
376 ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment,
377 bool split, bool realloc) {
378 assert(partition_size <= size(), "partition failed");
379 if (split) {
380 os::split_reserved_memory(base(), size(), partition_size, realloc);
381 }
382 ReservedSpace result(base(), partition_size, alignment, special(),
383 executable());
384 return result;
385 }
386
387
388 ReservedSpace
389 ReservedSpace::last_part(size_t partition_size, size_t alignment) {
390 assert(partition_size <= size(), "partition failed");
391 ReservedSpace result(base() + partition_size, size() - partition_size,
392 alignment, special(), executable());
393 return result;
394 }
395
396
397 size_t ReservedSpace::page_align_size_up(size_t size) {
398 return align_size_up(size, os::vm_page_size());
399 }
400
401
402 size_t ReservedSpace::page_align_size_down(size_t size) {
403 return align_size_down(size, os::vm_page_size());
404 }
405
406
407 size_t ReservedSpace::allocation_align_size_up(size_t size) {
408 return align_size_up(size, os::vm_allocation_granularity());
409 }
410
411
412 size_t ReservedSpace::allocation_align_size_down(size_t size) {
413 return align_size_down(size, os::vm_allocation_granularity());
414 }
415
416
417 void ReservedSpace::release() {
418 if (is_reserved()) {
419 char *real_base = _base - _noaccess_prefix;
420 const size_t real_size = _size + _noaccess_prefix;
421 if (special()) {
422 os::release_memory_special(real_base, real_size);
423 } else{
424 os::release_memory(real_base, real_size);
425 }
426 _base = NULL;
427 _size = 0;
428 _noaccess_prefix = 0;
429 _special = false;
430 _executable = false;
431 }
432 }
433
434 void ReservedSpace::protect_noaccess_prefix(const size_t size) {
435 assert( (_noaccess_prefix != 0) == (UseCompressedOops && _base != NULL &&
436 (Universe::narrow_oop_base() != NULL) &&
437 Universe::narrow_oop_use_implicit_null_checks()),
438 "noaccess_prefix should be used only with non zero based compressed oops");
439
440 // If there is no noaccess prefix, return.
441 if (_noaccess_prefix == 0) return;
442
443 assert(_noaccess_prefix >= (size_t)os::vm_page_size(),
444 "must be at least page size big");
445
446 // Protect memory at the base of the allocated region.
447 // If special, the page was committed (only matters on windows)
448 if (!os::protect_memory(_base, _noaccess_prefix, os::MEM_PROT_NONE,
449 _special)) {
450 fatal("cannot protect protection page");
451 }
452 if (PrintCompressedOopsMode) {
453 tty->cr();
454 tty->print_cr("Protected page at the reserved heap base: " PTR_FORMAT " / " INTX_FORMAT " bytes", _base, _noaccess_prefix);
455 }
456
457 _base += _noaccess_prefix;
458 _size -= _noaccess_prefix;
459 assert((size == _size) && ((uintptr_t)_base % _alignment == 0),
460 "must be exactly of required size and alignment");
461 }
462
463 ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment,
464 bool large, char* requested_address) :
465 ReservedSpace(size, alignment, large,
466 requested_address,
467 (UseCompressedOops && (Universe::narrow_oop_base() != NULL) &&
468 Universe::narrow_oop_use_implicit_null_checks()) ?
469 lcm(os::vm_page_size(), alignment) : 0) {
470 if (base() > 0) {
471 MemTracker::record_virtual_memory_type((address)base(), mtJavaHeap);
472 }
473
474 // Only reserved space for the java heap should have a noaccess_prefix
475 // if using compressed oops.
476 protect_noaccess_prefix(size);
477 }
478
479 ReservedHeapSpace::ReservedHeapSpace(const size_t heap_space_size,
480 const size_t alignment,
481 char* requested_address) :
482 ReservedSpace(heap_space_size, alignment,
483 requested_address,
484 (UseCompressedOops && (Universe::narrow_oop_base() != NULL) &&
485 Universe::narrow_oop_use_implicit_null_checks()) ?
486 lcm(os::vm_page_size(), alignment) : 0) {
487 if (base() > 0) {
488 MemTracker::record_virtual_memory_type((address)base(), mtJavaHeap);
489 }
490 protect_noaccess_prefix(heap_space_size);
491 }
492
493 // Reserve space for code segment. Same as Java heap only we mark this as
494 // executable.
495 ReservedCodeSpace::ReservedCodeSpace(size_t r_size,
496 size_t rs_align,
497 bool large) :
498 ReservedSpace(r_size, rs_align, large, /*executable*/ true) {
499 MemTracker::record_virtual_memory_type((address)base(), mtCode);
500 }
501
502 // VirtualSpace
503
504 VirtualSpace::VirtualSpace() {
505 _low_boundary = NULL;
506 _high_boundary = NULL;
507 _low = NULL;
508 _high = NULL;
509 _lower_high = NULL;
510 _middle_high = NULL;
511 _upper_high = NULL;
512 _lower_high_boundary = NULL;
513 _middle_high_boundary = NULL;
514 _upper_high_boundary = NULL;
515 _lower_alignment = 0;
516 _middle_alignment = 0;
517 _upper_alignment = 0;
518 _special = false;
519 _executable = false;
520 }
521
522
523 bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) {
524 if(!rs.is_reserved()) return false; // allocation failed.
525 assert(_low_boundary == NULL, "VirtualSpace already initialized");
526 _low_boundary = rs.base();
527 _high_boundary = low_boundary() + rs.size();
528
529 _low = low_boundary();
530 _high = low();
531
532 _special = rs.special();
533 _executable = rs.executable();
534
535 // When a VirtualSpace begins life at a large size, make all future expansion
536 // and shrinking occur aligned to a granularity of large pages. This avoids
537 // fragmentation of physical addresses that inhibits the use of large pages
538 // by the OS virtual memory system. Empirically, we see that with a 4MB
539 // page size, the only spaces that get handled this way are codecache and
540 // the heap itself, both of which provide a substantial performance
541 // boost in many benchmarks when covered by large pages.
542 //
543 // No attempt is made to force large page alignment at the very top and
544 // bottom of the space if they are not aligned so already.
545 _lower_alignment = os::vm_page_size();
546 _middle_alignment = os::page_size_for_region(rs.size(), rs.size(), 1);
547 _upper_alignment = os::vm_page_size();
548
549 // End of each region
550 _lower_high_boundary = (char*) round_to((intptr_t) low_boundary(), middle_alignment());
551 _middle_high_boundary = (char*) round_down((intptr_t) high_boundary(), middle_alignment());
552 _upper_high_boundary = high_boundary();
553
554 // High address of each region
555 _lower_high = low_boundary();
556 _middle_high = lower_high_boundary();
557 _upper_high = middle_high_boundary();
558
559 // commit to initial size
560 if (committed_size > 0) {
561 if (!expand_by(committed_size)) {
562 return false;
563 }
564 }
565 return true;
566 }
567
568
569 VirtualSpace::~VirtualSpace() {
570 release();
571 }
572
573
574 void VirtualSpace::release() {
575 // This does not release memory it never reserved.
576 // Caller must release via rs.release();
577 _low_boundary = NULL;
578 _high_boundary = NULL;
579 _low = NULL;
580 _high = NULL;
581 _lower_high = NULL;
582 _middle_high = NULL;
583 _upper_high = NULL;
584 _lower_high_boundary = NULL;
585 _middle_high_boundary = NULL;
586 _upper_high_boundary = NULL;
587 _lower_alignment = 0;
588 _middle_alignment = 0;
589 _upper_alignment = 0;
590 _special = false;
591 _executable = false;
592 }
593
594
595 size_t VirtualSpace::committed_size() const {
596 return pointer_delta(high(), low(), sizeof(char));
597 }
598
599
600 size_t VirtualSpace::reserved_size() const {
601 return pointer_delta(high_boundary(), low_boundary(), sizeof(char));
602 }
603
604
605 size_t VirtualSpace::uncommitted_size() const {
606 return reserved_size() - committed_size();
607 }
608
609
610 bool VirtualSpace::contains(const void* p) const {
611 return low() <= (const char*) p && (const char*) p < high();
612 }
613
614 /*
615 First we need to determine if a particular virtual space is using large
616 pages. This is done at the initialize function and only virtual spaces
617 that are larger than LargePageSizeInBytes use large pages. Once we
618 have determined this, all expand_by and shrink_by calls must grow and
619 shrink by large page size chunks. If a particular request
620 is within the current large page, the call to commit and uncommit memory
621 can be ignored. In the case that the low and high boundaries of this
622 space is not large page aligned, the pages leading to the first large
623 page address and the pages after the last large page address must be
624 allocated with default pages.
625 */
626 bool VirtualSpace::expand_by(size_t bytes, bool pre_touch) {
627 if (uncommitted_size() < bytes) return false;
628
629 if (special()) {
630 // don't commit memory if the entire space is pinned in memory
631 _high += bytes;
632 return true;
633 }
634
635 char* previous_high = high();
636 char* unaligned_new_high = high() + bytes;
637 assert(unaligned_new_high <= high_boundary(),
638 "cannot expand by more than upper boundary");
639
640 // Calculate where the new high for each of the regions should be. If
641 // the low_boundary() and high_boundary() are LargePageSizeInBytes aligned
642 // then the unaligned lower and upper new highs would be the
643 // lower_high() and upper_high() respectively.
644 char* unaligned_lower_new_high =
645 MIN2(unaligned_new_high, lower_high_boundary());
646 char* unaligned_middle_new_high =
647 MIN2(unaligned_new_high, middle_high_boundary());
648 char* unaligned_upper_new_high =
649 MIN2(unaligned_new_high, upper_high_boundary());
650
651 // Align the new highs based on the regions alignment. lower and upper
652 // alignment will always be default page size. middle alignment will be
653 // LargePageSizeInBytes if the actual size of the virtual space is in
654 // fact larger than LargePageSizeInBytes.
655 char* aligned_lower_new_high =
656 (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment());
657 char* aligned_middle_new_high =
658 (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment());
659 char* aligned_upper_new_high =
660 (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment());
661
662 // Determine which regions need to grow in this expand_by call.
663 // If you are growing in the lower region, high() must be in that
664 // region so calcuate the size based on high(). For the middle and
665 // upper regions, determine the starting point of growth based on the
666 // location of high(). By getting the MAX of the region's low address
667 // (or the prevoius region's high address) and high(), we can tell if it
668 // is an intra or inter region growth.
669 size_t lower_needs = 0;
670 if (aligned_lower_new_high > lower_high()) {
671 lower_needs =
672 pointer_delta(aligned_lower_new_high, lower_high(), sizeof(char));
673 }
674 size_t middle_needs = 0;
675 if (aligned_middle_new_high > middle_high()) {
676 middle_needs =
677 pointer_delta(aligned_middle_new_high, middle_high(), sizeof(char));
678 }
679 size_t upper_needs = 0;
680 if (aligned_upper_new_high > upper_high()) {
681 upper_needs =
682 pointer_delta(aligned_upper_new_high, upper_high(), sizeof(char));
683 }
684
685 // Check contiguity.
686 assert(low_boundary() <= lower_high() &&
687 lower_high() <= lower_high_boundary(),
688 "high address must be contained within the region");
689 assert(lower_high_boundary() <= middle_high() &&
690 middle_high() <= middle_high_boundary(),
691 "high address must be contained within the region");
692 assert(middle_high_boundary() <= upper_high() &&
693 upper_high() <= upper_high_boundary(),
694 "high address must be contained within the region");
695
696 // Commit regions
697 if (lower_needs > 0) {
698 assert(low_boundary() <= lower_high() &&
699 lower_high() + lower_needs <= lower_high_boundary(),
700 "must not expand beyond region");
701 if (!os::commit_memory(lower_high(), lower_needs, _executable)) {
702 debug_only(warning("os::commit_memory failed"));
703 return false;
704 } else {
705 _lower_high += lower_needs;
706 }
707 }
708 if (middle_needs > 0) {
709 assert(lower_high_boundary() <= middle_high() &&
710 middle_high() + middle_needs <= middle_high_boundary(),
711 "must not expand beyond region");
712 if (!os::commit_memory(middle_high(), middle_needs, middle_alignment(),
713 _executable)) {
714 debug_only(warning("os::commit_memory failed"));
715 return false;
716 }
717 _middle_high += middle_needs;
718 }
719 if (upper_needs > 0) {
720 assert(middle_high_boundary() <= upper_high() &&
721 upper_high() + upper_needs <= upper_high_boundary(),
722 "must not expand beyond region");
723 if (!os::commit_memory(upper_high(), upper_needs, _executable)) {
724 debug_only(warning("os::commit_memory failed"));
725 return false;
726 } else {
727 _upper_high += upper_needs;
728 }
729 }
730
731 if (pre_touch || AlwaysPreTouch) {
732 int vm_ps = os::vm_page_size();
733 for (char* curr = previous_high;
734 curr < unaligned_new_high;
735 curr += vm_ps) {
736 // Note the use of a write here; originally we tried just a read, but
737 // since the value read was unused, the optimizer removed the read.
738 // If we ever have a concurrent touchahead thread, we'll want to use
739 // a read, to avoid the potential of overwriting data (if a mutator
740 // thread beats the touchahead thread to a page). There are various
741 // ways of making sure this read is not optimized away: for example,
742 // generating the code for a read procedure at runtime.
743 *curr = 0;
744 }
745 }
746
747 _high += bytes;
748 return true;
749 }
750
751 // A page is uncommitted if the contents of the entire page is deemed unusable.
752 // Continue to decrement the high() pointer until it reaches a page boundary
753 // in which case that particular page can now be uncommitted.
754 void VirtualSpace::shrink_by(size_t size) {
755 if (committed_size() < size)
756 fatal("Cannot shrink virtual space to negative size");
757
758 if (special()) {
759 // don't uncommit if the entire space is pinned in memory
760 _high -= size;
761 return;
762 }
763
764 char* unaligned_new_high = high() - size;
765 assert(unaligned_new_high >= low_boundary(), "cannot shrink past lower boundary");
766
767 // Calculate new unaligned address
768 char* unaligned_upper_new_high =
769 MAX2(unaligned_new_high, middle_high_boundary());
770 char* unaligned_middle_new_high =
771 MAX2(unaligned_new_high, lower_high_boundary());
772 char* unaligned_lower_new_high =
773 MAX2(unaligned_new_high, low_boundary());
774
775 // Align address to region's alignment
776 char* aligned_upper_new_high =
777 (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment());
778 char* aligned_middle_new_high =
779 (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment());
780 char* aligned_lower_new_high =
781 (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment());
782
783 // Determine which regions need to shrink
784 size_t upper_needs = 0;
785 if (aligned_upper_new_high < upper_high()) {
786 upper_needs =
787 pointer_delta(upper_high(), aligned_upper_new_high, sizeof(char));
788 }
789 size_t middle_needs = 0;
790 if (aligned_middle_new_high < middle_high()) {
791 middle_needs =
792 pointer_delta(middle_high(), aligned_middle_new_high, sizeof(char));
793 }
794 size_t lower_needs = 0;
795 if (aligned_lower_new_high < lower_high()) {
796 lower_needs =
797 pointer_delta(lower_high(), aligned_lower_new_high, sizeof(char));
798 }
799
800 // Check contiguity.
801 assert(middle_high_boundary() <= upper_high() &&
802 upper_high() <= upper_high_boundary(),
803 "high address must be contained within the region");
804 assert(lower_high_boundary() <= middle_high() &&
805 middle_high() <= middle_high_boundary(),
806 "high address must be contained within the region");
807 assert(low_boundary() <= lower_high() &&
808 lower_high() <= lower_high_boundary(),
809 "high address must be contained within the region");
810
811 // Uncommit
812 if (upper_needs > 0) {
813 assert(middle_high_boundary() <= aligned_upper_new_high &&
814 aligned_upper_new_high + upper_needs <= upper_high_boundary(),
815 "must not shrink beyond region");
816 if (!os::uncommit_memory(aligned_upper_new_high, upper_needs)) {
817 debug_only(warning("os::uncommit_memory failed"));
818 return;
819 } else {
820 _upper_high -= upper_needs;
821 }
822 }
823 if (middle_needs > 0) {
824 assert(lower_high_boundary() <= aligned_middle_new_high &&
825 aligned_middle_new_high + middle_needs <= middle_high_boundary(),
826 "must not shrink beyond region");
827 if (!os::uncommit_memory(aligned_middle_new_high, middle_needs)) {
828 debug_only(warning("os::uncommit_memory failed"));
829 return;
830 } else {
831 _middle_high -= middle_needs;
832 }
833 }
834 if (lower_needs > 0) {
835 assert(low_boundary() <= aligned_lower_new_high &&
836 aligned_lower_new_high + lower_needs <= lower_high_boundary(),
837 "must not shrink beyond region");
838 if (!os::uncommit_memory(aligned_lower_new_high, lower_needs)) {
839 debug_only(warning("os::uncommit_memory failed"));
840 return;
841 } else {
842 _lower_high -= lower_needs;
843 }
844 }
845
846 _high -= size;
847 }
848
849 #ifndef PRODUCT
850 void VirtualSpace::check_for_contiguity() {
851 // Check contiguity.
852 assert(low_boundary() <= lower_high() &&
853 lower_high() <= lower_high_boundary(),
854 "high address must be contained within the region");
855 assert(lower_high_boundary() <= middle_high() &&
856 middle_high() <= middle_high_boundary(),
857 "high address must be contained within the region");
858 assert(middle_high_boundary() <= upper_high() &&
859 upper_high() <= upper_high_boundary(),
860 "high address must be contained within the region");
861 assert(low() >= low_boundary(), "low");
862 assert(low_boundary() <= lower_high_boundary(), "lower high boundary");
863 assert(upper_high_boundary() <= high_boundary(), "upper high boundary");
864 assert(high() <= upper_high(), "upper high");
865 }
866
867 void VirtualSpace::print() {
868 tty->print ("Virtual space:");
869 if (special()) tty->print(" (pinned in memory)");
870 tty->cr();
871 tty->print_cr(" - committed: %ld", committed_size());
872 tty->print_cr(" - reserved: %ld", reserved_size());
873 tty->print_cr(" - [low, high]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]", low(), high());
874 tty->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]", low_boundary(), high_boundary());
875 }
876
877 #endif