Mercurial > hg > graal-compiler
annotate src/share/vm/runtime/virtualspace.cpp @ 237:1fdb98a17101
6716785: implicit null checks not triggering with CompressedOops
Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check
Reviewed-by: kvn, jmasa, phh, jcoomes
| author | coleenp |
|---|---|
| date | Sat, 19 Jul 2008 17:38:22 -0400 |
| parents | a61af66fc99e |
| children | 93befa083681 1ee8caae33af |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 * Copyright 1997-2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 #include "incls/_precompiled.incl" | |
| 26 #include "incls/_virtualspace.cpp.incl" | |
| 27 | |
| 28 | |
| 29 // ReservedSpace | |
| 30 ReservedSpace::ReservedSpace(size_t size) { | |
|
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31 initialize(size, 0, false, NULL, 0); |
| 0 | 32 } |
| 33 | |
| 34 ReservedSpace::ReservedSpace(size_t size, size_t alignment, | |
|
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35 bool large, |
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36 char* requested_address, |
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37 const size_t noaccess_prefix) { |
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38 initialize(size+noaccess_prefix, alignment, large, requested_address, |
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39 noaccess_prefix); |
| 0 | 40 } |
| 41 | |
| 42 char * | |
| 43 ReservedSpace::align_reserved_region(char* addr, const size_t len, | |
| 44 const size_t prefix_size, | |
| 45 const size_t prefix_align, | |
| 46 const size_t suffix_size, | |
| 47 const size_t suffix_align) | |
| 48 { | |
| 49 assert(addr != NULL, "sanity"); | |
| 50 const size_t required_size = prefix_size + suffix_size; | |
| 51 assert(len >= required_size, "len too small"); | |
| 52 | |
| 53 const size_t s = size_t(addr); | |
| 54 const size_t beg_ofs = s + prefix_size & suffix_align - 1; | |
| 55 const size_t beg_delta = beg_ofs == 0 ? 0 : suffix_align - beg_ofs; | |
| 56 | |
| 57 if (len < beg_delta + required_size) { | |
| 58 return NULL; // Cannot do proper alignment. | |
| 59 } | |
| 60 const size_t end_delta = len - (beg_delta + required_size); | |
| 61 | |
| 62 if (beg_delta != 0) { | |
| 63 os::release_memory(addr, beg_delta); | |
| 64 } | |
| 65 | |
| 66 if (end_delta != 0) { | |
| 67 char* release_addr = (char*) (s + beg_delta + required_size); | |
| 68 os::release_memory(release_addr, end_delta); | |
| 69 } | |
| 70 | |
| 71 return (char*) (s + beg_delta); | |
| 72 } | |
| 73 | |
| 74 char* ReservedSpace::reserve_and_align(const size_t reserve_size, | |
| 75 const size_t prefix_size, | |
| 76 const size_t prefix_align, | |
| 77 const size_t suffix_size, | |
| 78 const size_t suffix_align) | |
| 79 { | |
| 80 assert(reserve_size > prefix_size + suffix_size, "should not be here"); | |
| 81 | |
| 82 char* raw_addr = os::reserve_memory(reserve_size, NULL, prefix_align); | |
| 83 if (raw_addr == NULL) return NULL; | |
| 84 | |
| 85 char* result = align_reserved_region(raw_addr, reserve_size, prefix_size, | |
| 86 prefix_align, suffix_size, | |
| 87 suffix_align); | |
| 88 if (result == NULL && !os::release_memory(raw_addr, reserve_size)) { | |
| 89 fatal("os::release_memory failed"); | |
| 90 } | |
| 91 | |
| 92 #ifdef ASSERT | |
| 93 if (result != NULL) { | |
| 94 const size_t raw = size_t(raw_addr); | |
| 95 const size_t res = size_t(result); | |
| 96 assert(res >= raw, "alignment decreased start addr"); | |
| 97 assert(res + prefix_size + suffix_size <= raw + reserve_size, | |
| 98 "alignment increased end addr"); | |
| 99 assert((res & prefix_align - 1) == 0, "bad alignment of prefix"); | |
| 100 assert((res + prefix_size & suffix_align - 1) == 0, | |
| 101 "bad alignment of suffix"); | |
| 102 } | |
| 103 #endif | |
| 104 | |
| 105 return result; | |
| 106 } | |
| 107 | |
| 108 ReservedSpace::ReservedSpace(const size_t prefix_size, | |
| 109 const size_t prefix_align, | |
| 110 const size_t suffix_size, | |
|
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111 const size_t suffix_align, |
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112 const size_t noaccess_prefix) |
| 0 | 113 { |
| 114 assert(prefix_size != 0, "sanity"); | |
| 115 assert(prefix_align != 0, "sanity"); | |
| 116 assert(suffix_size != 0, "sanity"); | |
| 117 assert(suffix_align != 0, "sanity"); | |
| 118 assert((prefix_size & prefix_align - 1) == 0, | |
| 119 "prefix_size not divisible by prefix_align"); | |
| 120 assert((suffix_size & suffix_align - 1) == 0, | |
| 121 "suffix_size not divisible by suffix_align"); | |
| 122 assert((suffix_align & prefix_align - 1) == 0, | |
| 123 "suffix_align not divisible by prefix_align"); | |
| 124 | |
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125 // Add in noaccess_prefix to prefix_size; |
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126 const size_t adjusted_prefix_size = prefix_size + noaccess_prefix; |
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127 const size_t size = adjusted_prefix_size + suffix_size; |
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128 |
| 0 | 129 // On systems where the entire region has to be reserved and committed up |
| 130 // front, the compound alignment normally done by this method is unnecessary. | |
| 131 const bool try_reserve_special = UseLargePages && | |
| 132 prefix_align == os::large_page_size(); | |
| 133 if (!os::can_commit_large_page_memory() && try_reserve_special) { | |
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134 initialize(size, prefix_align, true, NULL, noaccess_prefix); |
| 0 | 135 return; |
| 136 } | |
| 137 | |
| 138 _base = NULL; | |
| 139 _size = 0; | |
| 140 _alignment = 0; | |
| 141 _special = false; | |
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142 _noaccess_prefix = 0; |
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143 |
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144 // Assert that if noaccess_prefix is used, it is the same as prefix_align. |
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145 assert(noaccess_prefix == 0 || |
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146 noaccess_prefix == prefix_align, "noaccess prefix wrong"); |
| 0 | 147 |
| 148 // Optimistically try to reserve the exact size needed. | |
| 149 char* addr = os::reserve_memory(size, NULL, prefix_align); | |
| 150 if (addr == NULL) return; | |
| 151 | |
| 152 // Check whether the result has the needed alignment (unlikely unless | |
| 153 // prefix_align == suffix_align). | |
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154 const size_t ofs = size_t(addr) + adjusted_prefix_size & suffix_align - 1; |
| 0 | 155 if (ofs != 0) { |
| 156 // Wrong alignment. Release, allocate more space and do manual alignment. | |
| 157 // | |
| 158 // On most operating systems, another allocation with a somewhat larger size | |
| 159 // will return an address "close to" that of the previous allocation. The | |
| 160 // result is often the same address (if the kernel hands out virtual | |
| 161 // addresses from low to high), or an address that is offset by the increase | |
| 162 // in size. Exploit that to minimize the amount of extra space requested. | |
| 163 if (!os::release_memory(addr, size)) { | |
| 164 fatal("os::release_memory failed"); | |
| 165 } | |
| 166 | |
| 167 const size_t extra = MAX2(ofs, suffix_align - ofs); | |
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168 addr = reserve_and_align(size + extra, adjusted_prefix_size, prefix_align, |
| 0 | 169 suffix_size, suffix_align); |
| 170 if (addr == NULL) { | |
| 171 // Try an even larger region. If this fails, address space is exhausted. | |
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172 addr = reserve_and_align(size + suffix_align, adjusted_prefix_size, |
| 0 | 173 prefix_align, suffix_size, suffix_align); |
| 174 } | |
| 175 } | |
| 176 | |
| 177 _base = addr; | |
| 178 _size = size; | |
| 179 _alignment = prefix_align; | |
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180 _noaccess_prefix = noaccess_prefix; |
| 0 | 181 } |
| 182 | |
| 183 void ReservedSpace::initialize(size_t size, size_t alignment, bool large, | |
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184 char* requested_address, |
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185 const size_t noaccess_prefix) { |
| 0 | 186 const size_t granularity = os::vm_allocation_granularity(); |
| 187 assert((size & granularity - 1) == 0, | |
| 188 "size not aligned to os::vm_allocation_granularity()"); | |
| 189 assert((alignment & granularity - 1) == 0, | |
| 190 "alignment not aligned to os::vm_allocation_granularity()"); | |
| 191 assert(alignment == 0 || is_power_of_2((intptr_t)alignment), | |
| 192 "not a power of 2"); | |
| 193 | |
| 194 _base = NULL; | |
| 195 _size = 0; | |
| 196 _special = false; | |
| 197 _alignment = 0; | |
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198 _noaccess_prefix = 0; |
| 0 | 199 if (size == 0) { |
| 200 return; | |
| 201 } | |
| 202 | |
| 203 // If OS doesn't support demand paging for large page memory, we need | |
| 204 // to use reserve_memory_special() to reserve and pin the entire region. | |
| 205 bool special = large && !os::can_commit_large_page_memory(); | |
| 206 char* base = NULL; | |
| 207 | |
| 208 if (special) { | |
| 209 // It's not hard to implement reserve_memory_special() such that it can | |
| 210 // allocate at fixed address, but there seems no use of this feature | |
| 211 // for now, so it's not implemented. | |
| 212 assert(requested_address == NULL, "not implemented"); | |
| 213 | |
| 214 base = os::reserve_memory_special(size); | |
| 215 | |
| 216 if (base != NULL) { | |
| 217 // Check alignment constraints | |
| 218 if (alignment > 0) { | |
| 219 assert((uintptr_t) base % alignment == 0, | |
| 220 "Large pages returned a non-aligned address"); | |
| 221 } | |
| 222 _special = true; | |
| 223 } else { | |
| 224 // failed; try to reserve regular memory below | |
| 225 } | |
| 226 } | |
| 227 | |
| 228 if (base == NULL) { | |
| 229 // Optimistically assume that the OSes returns an aligned base pointer. | |
| 230 // When reserving a large address range, most OSes seem to align to at | |
| 231 // least 64K. | |
| 232 | |
| 233 // If the memory was requested at a particular address, use | |
| 234 // os::attempt_reserve_memory_at() to avoid over mapping something | |
| 235 // important. If available space is not detected, return NULL. | |
| 236 | |
| 237 if (requested_address != 0) { | |
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238 base = os::attempt_reserve_memory_at(size, |
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239 requested_address-noaccess_prefix); |
| 0 | 240 } else { |
| 241 base = os::reserve_memory(size, NULL, alignment); | |
| 242 } | |
| 243 | |
| 244 if (base == NULL) return; | |
| 245 | |
| 246 // Check alignment constraints | |
| 247 if (alignment > 0 && ((size_t)base & alignment - 1) != 0) { | |
| 248 // Base not aligned, retry | |
| 249 if (!os::release_memory(base, size)) fatal("os::release_memory failed"); | |
| 250 // Reserve size large enough to do manual alignment and | |
| 251 // increase size to a multiple of the desired alignment | |
| 252 size = align_size_up(size, alignment); | |
| 253 size_t extra_size = size + alignment; | |
| 254 char* extra_base = os::reserve_memory(extra_size, NULL, alignment); | |
| 255 if (extra_base == NULL) return; | |
| 256 // Do manual alignement | |
| 257 base = (char*) align_size_up((uintptr_t) extra_base, alignment); | |
| 258 assert(base >= extra_base, "just checking"); | |
| 259 // Release unused areas | |
| 260 size_t unused_bottom_size = base - extra_base; | |
| 261 size_t unused_top_size = extra_size - size - unused_bottom_size; | |
| 262 assert(unused_bottom_size % os::vm_allocation_granularity() == 0, | |
| 263 "size not allocation aligned"); | |
| 264 assert(unused_top_size % os::vm_allocation_granularity() == 0, | |
| 265 "size not allocation aligned"); | |
| 266 if (unused_bottom_size > 0) { | |
| 267 os::release_memory(extra_base, unused_bottom_size); | |
| 268 } | |
| 269 if (unused_top_size > 0) { | |
| 270 os::release_memory(base + size, unused_top_size); | |
| 271 } | |
| 272 } | |
| 273 } | |
| 274 // Done | |
| 275 _base = base; | |
| 276 _size = size; | |
| 277 _alignment = MAX2(alignment, (size_t) os::vm_page_size()); | |
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278 _noaccess_prefix = noaccess_prefix; |
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279 |
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280 // Assert that if noaccess_prefix is used, it is the same as alignment. |
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281 assert(noaccess_prefix == 0 || |
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282 noaccess_prefix == _alignment, "noaccess prefix wrong"); |
| 0 | 283 |
| 284 assert(markOopDesc::encode_pointer_as_mark(_base)->decode_pointer() == _base, | |
| 285 "area must be distinguisable from marks for mark-sweep"); | |
| 286 assert(markOopDesc::encode_pointer_as_mark(&_base[size])->decode_pointer() == &_base[size], | |
| 287 "area must be distinguisable from marks for mark-sweep"); | |
| 288 } | |
| 289 | |
| 290 | |
| 291 ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment, | |
| 292 bool special) { | |
| 293 assert((size % os::vm_allocation_granularity()) == 0, | |
| 294 "size not allocation aligned"); | |
| 295 _base = base; | |
| 296 _size = size; | |
| 297 _alignment = alignment; | |
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298 _noaccess_prefix = 0; |
| 0 | 299 _special = special; |
| 300 } | |
| 301 | |
| 302 | |
| 303 ReservedSpace ReservedSpace::first_part(size_t partition_size, size_t alignment, | |
| 304 bool split, bool realloc) { | |
| 305 assert(partition_size <= size(), "partition failed"); | |
| 306 if (split) { | |
| 307 os::split_reserved_memory(_base, _size, partition_size, realloc); | |
| 308 } | |
| 309 ReservedSpace result(base(), partition_size, alignment, special()); | |
| 310 return result; | |
| 311 } | |
| 312 | |
| 313 | |
| 314 ReservedSpace | |
| 315 ReservedSpace::last_part(size_t partition_size, size_t alignment) { | |
| 316 assert(partition_size <= size(), "partition failed"); | |
| 317 ReservedSpace result(base() + partition_size, size() - partition_size, | |
| 318 alignment, special()); | |
| 319 return result; | |
| 320 } | |
| 321 | |
| 322 | |
| 323 size_t ReservedSpace::page_align_size_up(size_t size) { | |
| 324 return align_size_up(size, os::vm_page_size()); | |
| 325 } | |
| 326 | |
| 327 | |
| 328 size_t ReservedSpace::page_align_size_down(size_t size) { | |
| 329 return align_size_down(size, os::vm_page_size()); | |
| 330 } | |
| 331 | |
| 332 | |
| 333 size_t ReservedSpace::allocation_align_size_up(size_t size) { | |
| 334 return align_size_up(size, os::vm_allocation_granularity()); | |
| 335 } | |
| 336 | |
| 337 | |
| 338 size_t ReservedSpace::allocation_align_size_down(size_t size) { | |
| 339 return align_size_down(size, os::vm_allocation_granularity()); | |
| 340 } | |
| 341 | |
| 342 | |
| 343 void ReservedSpace::release() { | |
| 344 if (is_reserved()) { | |
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345 char *real_base = _base - _noaccess_prefix; |
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346 const size_t real_size = _size + _noaccess_prefix; |
| 0 | 347 if (special()) { |
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348 os::release_memory_special(real_base, real_size); |
| 0 | 349 } else{ |
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350 os::release_memory(real_base, real_size); |
| 0 | 351 } |
| 352 _base = NULL; | |
| 353 _size = 0; | |
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354 _noaccess_prefix = 0; |
| 0 | 355 _special = false; |
| 356 } | |
| 357 } | |
| 358 | |
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359 void ReservedSpace::protect_noaccess_prefix(const size_t size) { |
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360 // If there is noaccess prefix, return. |
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361 if (_noaccess_prefix == 0) return; |
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362 |
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363 assert(_noaccess_prefix >= (size_t)os::vm_page_size(), |
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364 "must be at least page size big"); |
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365 |
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366 // Protect memory at the base of the allocated region. |
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367 // If special, the page was committed (only matters on windows) |
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368 if (!os::protect_memory(_base, _noaccess_prefix, os::MEM_PROT_NONE, |
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369 _special)) { |
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370 fatal("cannot protect protection page"); |
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371 } |
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372 |
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373 _base += _noaccess_prefix; |
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374 _size -= _noaccess_prefix; |
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375 assert((size == _size) && ((uintptr_t)_base % _alignment == 0), |
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376 "must be exactly of required size and alignment"); |
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377 } |
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378 |
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379 ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment, |
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380 bool large, char* requested_address) : |
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381 ReservedSpace(size, alignment, large, |
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382 requested_address, |
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383 UseCompressedOops ? lcm(os::vm_page_size(), alignment) : 0) { |
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384 // Only reserved space for the java heap should have a noaccess_prefix |
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385 // if using compressed oops. |
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386 protect_noaccess_prefix(size); |
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387 } |
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388 |
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389 ReservedHeapSpace::ReservedHeapSpace(const size_t prefix_size, |
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390 const size_t prefix_align, |
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391 const size_t suffix_size, |
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392 const size_t suffix_align) : |
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393 ReservedSpace(prefix_size, prefix_align, suffix_size, suffix_align, |
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394 UseCompressedOops ? lcm(os::vm_page_size(), prefix_align) : 0) { |
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395 protect_noaccess_prefix(prefix_size+suffix_size); |
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396 } |
| 0 | 397 |
| 398 // VirtualSpace | |
| 399 | |
| 400 VirtualSpace::VirtualSpace() { | |
| 401 _low_boundary = NULL; | |
| 402 _high_boundary = NULL; | |
| 403 _low = NULL; | |
| 404 _high = NULL; | |
| 405 _lower_high = NULL; | |
| 406 _middle_high = NULL; | |
| 407 _upper_high = NULL; | |
| 408 _lower_high_boundary = NULL; | |
| 409 _middle_high_boundary = NULL; | |
| 410 _upper_high_boundary = NULL; | |
| 411 _lower_alignment = 0; | |
| 412 _middle_alignment = 0; | |
| 413 _upper_alignment = 0; | |
|
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414 _special = false; |
| 0 | 415 } |
| 416 | |
| 417 | |
| 418 bool VirtualSpace::initialize(ReservedSpace rs, size_t committed_size) { | |
| 419 if(!rs.is_reserved()) return false; // allocation failed. | |
| 420 assert(_low_boundary == NULL, "VirtualSpace already initialized"); | |
| 421 _low_boundary = rs.base(); | |
| 422 _high_boundary = low_boundary() + rs.size(); | |
| 423 | |
| 424 _low = low_boundary(); | |
| 425 _high = low(); | |
| 426 | |
| 427 _special = rs.special(); | |
| 428 | |
| 429 // When a VirtualSpace begins life at a large size, make all future expansion | |
| 430 // and shrinking occur aligned to a granularity of large pages. This avoids | |
| 431 // fragmentation of physical addresses that inhibits the use of large pages | |
| 432 // by the OS virtual memory system. Empirically, we see that with a 4MB | |
| 433 // page size, the only spaces that get handled this way are codecache and | |
| 434 // the heap itself, both of which provide a substantial performance | |
| 435 // boost in many benchmarks when covered by large pages. | |
| 436 // | |
| 437 // No attempt is made to force large page alignment at the very top and | |
| 438 // bottom of the space if they are not aligned so already. | |
| 439 _lower_alignment = os::vm_page_size(); | |
| 440 _middle_alignment = os::page_size_for_region(rs.size(), rs.size(), 1); | |
| 441 _upper_alignment = os::vm_page_size(); | |
| 442 | |
| 443 // End of each region | |
| 444 _lower_high_boundary = (char*) round_to((intptr_t) low_boundary(), middle_alignment()); | |
| 445 _middle_high_boundary = (char*) round_down((intptr_t) high_boundary(), middle_alignment()); | |
| 446 _upper_high_boundary = high_boundary(); | |
| 447 | |
| 448 // High address of each region | |
| 449 _lower_high = low_boundary(); | |
| 450 _middle_high = lower_high_boundary(); | |
| 451 _upper_high = middle_high_boundary(); | |
| 452 | |
| 453 // commit to initial size | |
| 454 if (committed_size > 0) { | |
| 455 if (!expand_by(committed_size)) { | |
| 456 return false; | |
| 457 } | |
| 458 } | |
| 459 return true; | |
| 460 } | |
| 461 | |
| 462 | |
| 463 VirtualSpace::~VirtualSpace() { | |
| 464 release(); | |
| 465 } | |
| 466 | |
| 467 | |
| 468 void VirtualSpace::release() { | |
|
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469 // This does not release memory it never reserved. |
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470 // Caller must release via rs.release(); |
| 0 | 471 _low_boundary = NULL; |
| 472 _high_boundary = NULL; | |
| 473 _low = NULL; | |
| 474 _high = NULL; | |
| 475 _lower_high = NULL; | |
| 476 _middle_high = NULL; | |
| 477 _upper_high = NULL; | |
| 478 _lower_high_boundary = NULL; | |
| 479 _middle_high_boundary = NULL; | |
| 480 _upper_high_boundary = NULL; | |
| 481 _lower_alignment = 0; | |
| 482 _middle_alignment = 0; | |
| 483 _upper_alignment = 0; | |
| 484 _special = false; | |
| 485 } | |
| 486 | |
| 487 | |
| 488 size_t VirtualSpace::committed_size() const { | |
| 489 return pointer_delta(high(), low(), sizeof(char)); | |
| 490 } | |
| 491 | |
| 492 | |
| 493 size_t VirtualSpace::reserved_size() const { | |
| 494 return pointer_delta(high_boundary(), low_boundary(), sizeof(char)); | |
| 495 } | |
| 496 | |
| 497 | |
| 498 size_t VirtualSpace::uncommitted_size() const { | |
| 499 return reserved_size() - committed_size(); | |
| 500 } | |
| 501 | |
| 502 | |
| 503 bool VirtualSpace::contains(const void* p) const { | |
| 504 return low() <= (const char*) p && (const char*) p < high(); | |
| 505 } | |
| 506 | |
| 507 /* | |
| 508 First we need to determine if a particular virtual space is using large | |
| 509 pages. This is done at the initialize function and only virtual spaces | |
| 510 that are larger than LargePageSizeInBytes use large pages. Once we | |
| 511 have determined this, all expand_by and shrink_by calls must grow and | |
| 512 shrink by large page size chunks. If a particular request | |
| 513 is within the current large page, the call to commit and uncommit memory | |
| 514 can be ignored. In the case that the low and high boundaries of this | |
| 515 space is not large page aligned, the pages leading to the first large | |
| 516 page address and the pages after the last large page address must be | |
| 517 allocated with default pages. | |
| 518 */ | |
| 519 bool VirtualSpace::expand_by(size_t bytes, bool pre_touch) { | |
| 520 if (uncommitted_size() < bytes) return false; | |
| 521 | |
| 522 if (special()) { | |
| 523 // don't commit memory if the entire space is pinned in memory | |
| 524 _high += bytes; | |
| 525 return true; | |
| 526 } | |
| 527 | |
| 528 char* previous_high = high(); | |
| 529 char* unaligned_new_high = high() + bytes; | |
| 530 assert(unaligned_new_high <= high_boundary(), | |
| 531 "cannot expand by more than upper boundary"); | |
| 532 | |
| 533 // Calculate where the new high for each of the regions should be. If | |
| 534 // the low_boundary() and high_boundary() are LargePageSizeInBytes aligned | |
| 535 // then the unaligned lower and upper new highs would be the | |
| 536 // lower_high() and upper_high() respectively. | |
| 537 char* unaligned_lower_new_high = | |
| 538 MIN2(unaligned_new_high, lower_high_boundary()); | |
| 539 char* unaligned_middle_new_high = | |
| 540 MIN2(unaligned_new_high, middle_high_boundary()); | |
| 541 char* unaligned_upper_new_high = | |
| 542 MIN2(unaligned_new_high, upper_high_boundary()); | |
| 543 | |
| 544 // Align the new highs based on the regions alignment. lower and upper | |
| 545 // alignment will always be default page size. middle alignment will be | |
| 546 // LargePageSizeInBytes if the actual size of the virtual space is in | |
| 547 // fact larger than LargePageSizeInBytes. | |
| 548 char* aligned_lower_new_high = | |
| 549 (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment()); | |
| 550 char* aligned_middle_new_high = | |
| 551 (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment()); | |
| 552 char* aligned_upper_new_high = | |
| 553 (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment()); | |
| 554 | |
| 555 // Determine which regions need to grow in this expand_by call. | |
| 556 // If you are growing in the lower region, high() must be in that | |
| 557 // region so calcuate the size based on high(). For the middle and | |
| 558 // upper regions, determine the starting point of growth based on the | |
| 559 // location of high(). By getting the MAX of the region's low address | |
| 560 // (or the prevoius region's high address) and high(), we can tell if it | |
| 561 // is an intra or inter region growth. | |
| 562 size_t lower_needs = 0; | |
| 563 if (aligned_lower_new_high > lower_high()) { | |
| 564 lower_needs = | |
| 565 pointer_delta(aligned_lower_new_high, lower_high(), sizeof(char)); | |
| 566 } | |
| 567 size_t middle_needs = 0; | |
| 568 if (aligned_middle_new_high > middle_high()) { | |
| 569 middle_needs = | |
| 570 pointer_delta(aligned_middle_new_high, middle_high(), sizeof(char)); | |
| 571 } | |
| 572 size_t upper_needs = 0; | |
| 573 if (aligned_upper_new_high > upper_high()) { | |
| 574 upper_needs = | |
| 575 pointer_delta(aligned_upper_new_high, upper_high(), sizeof(char)); | |
| 576 } | |
| 577 | |
| 578 // Check contiguity. | |
| 579 assert(low_boundary() <= lower_high() && | |
| 580 lower_high() <= lower_high_boundary(), | |
| 581 "high address must be contained within the region"); | |
| 582 assert(lower_high_boundary() <= middle_high() && | |
| 583 middle_high() <= middle_high_boundary(), | |
| 584 "high address must be contained within the region"); | |
| 585 assert(middle_high_boundary() <= upper_high() && | |
| 586 upper_high() <= upper_high_boundary(), | |
| 587 "high address must be contained within the region"); | |
| 588 | |
| 589 // Commit regions | |
| 590 if (lower_needs > 0) { | |
| 591 assert(low_boundary() <= lower_high() && | |
| 592 lower_high() + lower_needs <= lower_high_boundary(), | |
| 593 "must not expand beyond region"); | |
| 594 if (!os::commit_memory(lower_high(), lower_needs)) { | |
| 595 debug_only(warning("os::commit_memory failed")); | |
| 596 return false; | |
| 597 } else { | |
| 598 _lower_high += lower_needs; | |
| 599 } | |
| 600 } | |
| 601 if (middle_needs > 0) { | |
| 602 assert(lower_high_boundary() <= middle_high() && | |
| 603 middle_high() + middle_needs <= middle_high_boundary(), | |
| 604 "must not expand beyond region"); | |
| 605 if (!os::commit_memory(middle_high(), middle_needs, middle_alignment())) { | |
| 606 debug_only(warning("os::commit_memory failed")); | |
| 607 return false; | |
| 608 } | |
| 609 _middle_high += middle_needs; | |
| 610 } | |
| 611 if (upper_needs > 0) { | |
| 612 assert(middle_high_boundary() <= upper_high() && | |
| 613 upper_high() + upper_needs <= upper_high_boundary(), | |
| 614 "must not expand beyond region"); | |
| 615 if (!os::commit_memory(upper_high(), upper_needs)) { | |
| 616 debug_only(warning("os::commit_memory failed")); | |
| 617 return false; | |
| 618 } else { | |
| 619 _upper_high += upper_needs; | |
| 620 } | |
| 621 } | |
| 622 | |
| 623 if (pre_touch || AlwaysPreTouch) { | |
| 624 int vm_ps = os::vm_page_size(); | |
| 625 for (char* curr = previous_high; | |
| 626 curr < unaligned_new_high; | |
| 627 curr += vm_ps) { | |
| 628 // Note the use of a write here; originally we tried just a read, but | |
| 629 // since the value read was unused, the optimizer removed the read. | |
| 630 // If we ever have a concurrent touchahead thread, we'll want to use | |
| 631 // a read, to avoid the potential of overwriting data (if a mutator | |
| 632 // thread beats the touchahead thread to a page). There are various | |
| 633 // ways of making sure this read is not optimized away: for example, | |
| 634 // generating the code for a read procedure at runtime. | |
| 635 *curr = 0; | |
| 636 } | |
| 637 } | |
| 638 | |
| 639 _high += bytes; | |
| 640 return true; | |
| 641 } | |
| 642 | |
| 643 // A page is uncommitted if the contents of the entire page is deemed unusable. | |
| 644 // Continue to decrement the high() pointer until it reaches a page boundary | |
| 645 // in which case that particular page can now be uncommitted. | |
| 646 void VirtualSpace::shrink_by(size_t size) { | |
| 647 if (committed_size() < size) | |
| 648 fatal("Cannot shrink virtual space to negative size"); | |
| 649 | |
| 650 if (special()) { | |
| 651 // don't uncommit if the entire space is pinned in memory | |
| 652 _high -= size; | |
| 653 return; | |
| 654 } | |
| 655 | |
| 656 char* unaligned_new_high = high() - size; | |
| 657 assert(unaligned_new_high >= low_boundary(), "cannot shrink past lower boundary"); | |
| 658 | |
| 659 // Calculate new unaligned address | |
| 660 char* unaligned_upper_new_high = | |
| 661 MAX2(unaligned_new_high, middle_high_boundary()); | |
| 662 char* unaligned_middle_new_high = | |
| 663 MAX2(unaligned_new_high, lower_high_boundary()); | |
| 664 char* unaligned_lower_new_high = | |
| 665 MAX2(unaligned_new_high, low_boundary()); | |
| 666 | |
| 667 // Align address to region's alignment | |
| 668 char* aligned_upper_new_high = | |
| 669 (char*) round_to((intptr_t) unaligned_upper_new_high, upper_alignment()); | |
| 670 char* aligned_middle_new_high = | |
| 671 (char*) round_to((intptr_t) unaligned_middle_new_high, middle_alignment()); | |
| 672 char* aligned_lower_new_high = | |
| 673 (char*) round_to((intptr_t) unaligned_lower_new_high, lower_alignment()); | |
| 674 | |
| 675 // Determine which regions need to shrink | |
| 676 size_t upper_needs = 0; | |
| 677 if (aligned_upper_new_high < upper_high()) { | |
| 678 upper_needs = | |
| 679 pointer_delta(upper_high(), aligned_upper_new_high, sizeof(char)); | |
| 680 } | |
| 681 size_t middle_needs = 0; | |
| 682 if (aligned_middle_new_high < middle_high()) { | |
| 683 middle_needs = | |
| 684 pointer_delta(middle_high(), aligned_middle_new_high, sizeof(char)); | |
| 685 } | |
| 686 size_t lower_needs = 0; | |
| 687 if (aligned_lower_new_high < lower_high()) { | |
| 688 lower_needs = | |
| 689 pointer_delta(lower_high(), aligned_lower_new_high, sizeof(char)); | |
| 690 } | |
| 691 | |
| 692 // Check contiguity. | |
| 693 assert(middle_high_boundary() <= upper_high() && | |
| 694 upper_high() <= upper_high_boundary(), | |
| 695 "high address must be contained within the region"); | |
| 696 assert(lower_high_boundary() <= middle_high() && | |
| 697 middle_high() <= middle_high_boundary(), | |
| 698 "high address must be contained within the region"); | |
| 699 assert(low_boundary() <= lower_high() && | |
| 700 lower_high() <= lower_high_boundary(), | |
| 701 "high address must be contained within the region"); | |
| 702 | |
| 703 // Uncommit | |
| 704 if (upper_needs > 0) { | |
| 705 assert(middle_high_boundary() <= aligned_upper_new_high && | |
| 706 aligned_upper_new_high + upper_needs <= upper_high_boundary(), | |
| 707 "must not shrink beyond region"); | |
| 708 if (!os::uncommit_memory(aligned_upper_new_high, upper_needs)) { | |
| 709 debug_only(warning("os::uncommit_memory failed")); | |
| 710 return; | |
| 711 } else { | |
| 712 _upper_high -= upper_needs; | |
| 713 } | |
| 714 } | |
| 715 if (middle_needs > 0) { | |
| 716 assert(lower_high_boundary() <= aligned_middle_new_high && | |
| 717 aligned_middle_new_high + middle_needs <= middle_high_boundary(), | |
| 718 "must not shrink beyond region"); | |
| 719 if (!os::uncommit_memory(aligned_middle_new_high, middle_needs)) { | |
| 720 debug_only(warning("os::uncommit_memory failed")); | |
| 721 return; | |
| 722 } else { | |
| 723 _middle_high -= middle_needs; | |
| 724 } | |
| 725 } | |
| 726 if (lower_needs > 0) { | |
| 727 assert(low_boundary() <= aligned_lower_new_high && | |
| 728 aligned_lower_new_high + lower_needs <= lower_high_boundary(), | |
| 729 "must not shrink beyond region"); | |
| 730 if (!os::uncommit_memory(aligned_lower_new_high, lower_needs)) { | |
| 731 debug_only(warning("os::uncommit_memory failed")); | |
| 732 return; | |
| 733 } else { | |
| 734 _lower_high -= lower_needs; | |
| 735 } | |
| 736 } | |
| 737 | |
| 738 _high -= size; | |
| 739 } | |
| 740 | |
| 741 #ifndef PRODUCT | |
| 742 void VirtualSpace::check_for_contiguity() { | |
| 743 // Check contiguity. | |
| 744 assert(low_boundary() <= lower_high() && | |
| 745 lower_high() <= lower_high_boundary(), | |
| 746 "high address must be contained within the region"); | |
| 747 assert(lower_high_boundary() <= middle_high() && | |
| 748 middle_high() <= middle_high_boundary(), | |
| 749 "high address must be contained within the region"); | |
| 750 assert(middle_high_boundary() <= upper_high() && | |
| 751 upper_high() <= upper_high_boundary(), | |
| 752 "high address must be contained within the region"); | |
| 753 assert(low() >= low_boundary(), "low"); | |
| 754 assert(low_boundary() <= lower_high_boundary(), "lower high boundary"); | |
| 755 assert(upper_high_boundary() <= high_boundary(), "upper high boundary"); | |
| 756 assert(high() <= upper_high(), "upper high"); | |
| 757 } | |
| 758 | |
| 759 void VirtualSpace::print() { | |
| 760 tty->print ("Virtual space:"); | |
| 761 if (special()) tty->print(" (pinned in memory)"); | |
| 762 tty->cr(); | |
| 763 tty->print_cr(" - committed: %ld", committed_size()); | |
| 764 tty->print_cr(" - reserved: %ld", reserved_size()); | |
| 765 tty->print_cr(" - [low, high]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]", low(), high()); | |
| 766 tty->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]", low_boundary(), high_boundary()); | |
| 767 } | |
| 768 | |
| 769 #endif |