1 /* 2 * Copyright (c) 2000, 2020, 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 "gc/shared/cardTable.hpp" 27 #include "gc/shared/collectedHeap.hpp" 28 #include "gc/shared/gcLogPrecious.hpp" 29 #include "gc/shared/gc_globals.hpp" 30 #include "gc/shared/space.inline.hpp" 31 #include "logging/log.hpp" 32 #include "memory/virtualspace.hpp" 33 #include "runtime/java.hpp" 34 #include "runtime/os.hpp" 35 #include "services/memTracker.hpp" 36 #include "utilities/align.hpp" 37 #if INCLUDE_PARALLELGC 38 #include "gc/parallel/objectStartArray.hpp" 39 #endif 40 41 uint CardTable::_card_shift = 0; 42 uint CardTable::_card_size = 0; 43 uint CardTable::_card_size_in_words = 0; 44 45 void CardTable::initialize_card_size() { 46 assert(UseG1GC || UseParallelGC || UseSerialGC || UseShenandoahGC, 47 "Initialize card size should only be called by card based collectors."); 48 49 _card_size = GCCardSizeInBytes; 50 _card_shift = log2i_exact(_card_size); 51 _card_size_in_words = _card_size / sizeof(HeapWord); 52 53 // Set blockOffsetTable size based on card table entry size 54 BOTConstants::initialize_bot_size(_card_shift); 55 56 #if INCLUDE_PARALLELGC 57 // Set ObjectStartArray block size based on card table entry size 58 ObjectStartArray::initialize_block_size(_card_shift); 59 #endif 60 61 log_info_p(gc, init)("CardTable entry size: " UINT32_FORMAT, _card_size); 62 } 63 64 size_t CardTable::compute_byte_map_size() { 65 assert(_guard_index == cards_required(_whole_heap.word_size()) - 1, 66 "uninitialized, check declaration order"); 67 assert(_page_size != 0, "uninitialized, check declaration order"); 68 const size_t granularity = os::vm_allocation_granularity(); 69 return align_up(_guard_index + 1, MAX2(_page_size, granularity)); 70 } 71 72 CardTable::CardTable(MemRegion whole_heap) : 73 _whole_heap(whole_heap), 74 _guard_index(0), 75 _last_valid_index(0), 76 _page_size(os::vm_page_size()), 77 _byte_map_size(0), 78 _byte_map(NULL), 79 _byte_map_base(NULL), 80 _cur_covered_regions(0), 81 _covered(MemRegion::create_array(_max_covered_regions, mtGC)), 82 _committed(MemRegion::create_array(_max_covered_regions, mtGC)), 83 _guard_region() 84 { 85 assert((uintptr_t(_whole_heap.start()) & (_card_size - 1)) == 0, "heap must start at card boundary"); 86 assert((uintptr_t(_whole_heap.end()) & (_card_size - 1)) == 0, "heap must end at card boundary"); 87 } 88 89 CardTable::~CardTable() { 90 MemRegion::destroy_array(_covered, _max_covered_regions); 91 MemRegion::destroy_array(_committed, _max_covered_regions); 92 } 93 94 void CardTable::initialize() { 95 _guard_index = cards_required(_whole_heap.word_size()) - 1; 96 _last_valid_index = _guard_index - 1; 97 98 _byte_map_size = compute_byte_map_size(); 99 100 HeapWord* low_bound = _whole_heap.start(); 101 HeapWord* high_bound = _whole_heap.end(); 102 103 _cur_covered_regions = 0; 104 105 const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 : 106 MAX2(_page_size, (size_t) os::vm_allocation_granularity()); 107 ReservedSpace heap_rs(_byte_map_size, rs_align, _page_size); 108 109 MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC); 110 111 os::trace_page_sizes("Card Table", _guard_index + 1, _guard_index + 1, 112 _page_size, heap_rs.base(), heap_rs.size()); 113 if (!heap_rs.is_reserved()) { 114 vm_exit_during_initialization("Could not reserve enough space for the " 115 "card marking array"); 116 } 117 118 // The assembler store_check code will do an unsigned shift of the oop, 119 // then add it to _byte_map_base, i.e. 120 // 121 // _byte_map = _byte_map_base + (uintptr_t(low_bound) >> card_shift) 122 _byte_map = (CardValue*) heap_rs.base(); 123 _byte_map_base = _byte_map - (uintptr_t(low_bound) >> _card_shift); 124 assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map"); 125 assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map"); 126 127 CardValue* guard_card = &_byte_map[_guard_index]; 128 HeapWord* guard_page = align_down((HeapWord*)guard_card, _page_size); 129 _guard_region = MemRegion(guard_page, _page_size); 130 os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size, 131 !ExecMem, "card table last card"); 132 *guard_card = last_card; 133 134 log_trace(gc, barrier)("CardTable::CardTable: "); 135 log_trace(gc, barrier)(" &_byte_map[0]: " INTPTR_FORMAT " &_byte_map[_last_valid_index]: " INTPTR_FORMAT, 136 p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index])); 137 log_trace(gc, barrier)(" _byte_map_base: " INTPTR_FORMAT, p2i(_byte_map_base)); 138 } 139 140 int CardTable::find_covering_region_by_base(HeapWord* base) { 141 int i; 142 for (i = 0; i < _cur_covered_regions; i++) { 143 if (_covered[i].start() == base) return i; 144 if (_covered[i].start() > base) break; 145 } 146 // If we didn't find it, create a new one. 147 assert(_cur_covered_regions < _max_covered_regions, 148 "too many covered regions"); 149 // Move the ones above up, to maintain sorted order. 150 for (int j = _cur_covered_regions; j > i; j--) { 151 _covered[j] = _covered[j-1]; 152 _committed[j] = _committed[j-1]; 153 } 154 int res = i; 155 _cur_covered_regions++; 156 _covered[res].set_start(base); 157 _covered[res].set_word_size(0); 158 CardValue* ct_start = byte_for(base); 159 HeapWord* ct_start_aligned = align_down((HeapWord*)ct_start, _page_size); 160 _committed[res].set_start(ct_start_aligned); 161 _committed[res].set_word_size(0); 162 return res; 163 } 164 165 HeapWord* CardTable::largest_prev_committed_end(int ind) const { 166 HeapWord* max_end = NULL; 167 for (int j = 0; j < ind; j++) { 168 HeapWord* this_end = _committed[j].end(); 169 if (this_end > max_end) max_end = this_end; 170 } 171 return max_end; 172 } 173 174 MemRegion CardTable::committed_unique_to_self(int self, MemRegion mr) const { 175 MemRegion result = mr; 176 for (int r = 0; r < _cur_covered_regions; r += 1) { 177 if (r != self) { 178 result = result.minus(_committed[r]); 179 } 180 } 181 // Never include the guard page. 182 result = result.minus(_guard_region); 183 return result; 184 } 185 186 void CardTable::resize_covered_region(MemRegion new_region) { 187 // We don't change the start of a region, only the end. 188 assert(_whole_heap.contains(new_region), 189 "attempt to cover area not in reserved area"); 190 debug_only(verify_guard();) 191 // collided is true if the expansion would push into another committed region 192 debug_only(bool collided = false;) 193 int const ind = find_covering_region_by_base(new_region.start()); 194 MemRegion const old_region = _covered[ind]; 195 assert(old_region.start() == new_region.start(), "just checking"); 196 if (new_region.word_size() != old_region.word_size()) { 197 // Commit new or uncommit old pages, if necessary. 198 MemRegion cur_committed = _committed[ind]; 199 // Extend the end of this _committed region 200 // to cover the end of any lower _committed regions. 201 // This forms overlapping regions, but never interior regions. 202 HeapWord* const max_prev_end = largest_prev_committed_end(ind); 203 if (max_prev_end > cur_committed.end()) { 204 cur_committed.set_end(max_prev_end); 205 } 206 // Align the end up to a page size (starts are already aligned). 207 HeapWord* new_end = (HeapWord*) byte_after(new_region.last()); 208 HeapWord* new_end_aligned = align_up(new_end, _page_size); 209 assert(new_end_aligned >= new_end, "align up, but less"); 210 // Check the other regions (excludes "ind") to ensure that 211 // the new_end_aligned does not intrude onto the committed 212 // space of another region. 213 int ri = 0; 214 for (ri = ind + 1; ri < _cur_covered_regions; ri++) { 215 if (new_end_aligned > _committed[ri].start()) { 216 assert(new_end_aligned <= _committed[ri].end(), 217 "An earlier committed region can't cover a later committed region"); 218 // Any region containing the new end 219 // should start at or beyond the region found (ind) 220 // for the new end (committed regions are not expected to 221 // be proper subsets of other committed regions). 222 assert(_committed[ri].start() >= _committed[ind].start(), 223 "New end of committed region is inconsistent"); 224 new_end_aligned = _committed[ri].start(); 225 // new_end_aligned can be equal to the start of its 226 // committed region (i.e., of "ind") if a second 227 // region following "ind" also start at the same location 228 // as "ind". 229 assert(new_end_aligned >= _committed[ind].start(), 230 "New end of committed region is before start"); 231 debug_only(collided = true;) 232 // Should only collide with 1 region 233 break; 234 } 235 } 236 #ifdef ASSERT 237 for (++ri; ri < _cur_covered_regions; ri++) { 238 assert(!_committed[ri].contains(new_end_aligned), 239 "New end of committed region is in a second committed region"); 240 } 241 #endif 242 // The guard page is always committed and should not be committed over. 243 // "guarded" is used for assertion checking below and recalls the fact 244 // that the would-be end of the new committed region would have 245 // penetrated the guard page. 246 HeapWord* new_end_for_commit = new_end_aligned; 247 248 DEBUG_ONLY(bool guarded = false;) 249 if (new_end_for_commit > _guard_region.start()) { 250 new_end_for_commit = _guard_region.start(); 251 DEBUG_ONLY(guarded = true;) 252 } 253 254 if (new_end_for_commit > cur_committed.end()) { 255 // Must commit new pages. 256 MemRegion const new_committed = 257 MemRegion(cur_committed.end(), new_end_for_commit); 258 259 assert(!new_committed.is_empty(), "Region should not be empty here"); 260 os::commit_memory_or_exit((char*)new_committed.start(), 261 new_committed.byte_size(), _page_size, 262 !ExecMem, "card table expansion"); 263 // Use new_end_aligned (as opposed to new_end_for_commit) because 264 // the cur_committed region may include the guard region. 265 } else if (new_end_aligned < cur_committed.end()) { 266 // Must uncommit pages. 267 MemRegion const uncommit_region = 268 committed_unique_to_self(ind, MemRegion(new_end_aligned, 269 cur_committed.end())); 270 if (!uncommit_region.is_empty()) { 271 if (!os::uncommit_memory((char*)uncommit_region.start(), 272 uncommit_region.byte_size())) { 273 assert(false, "Card table contraction failed"); 274 // The call failed so don't change the end of the 275 // committed region. This is better than taking the 276 // VM down. 277 new_end_aligned = _committed[ind].end(); 278 } 279 } 280 } 281 // In any case, we can reset the end of the current committed entry. 282 _committed[ind].set_end(new_end_aligned); 283 284 #ifdef ASSERT 285 // Check that the last card in the new region is committed according 286 // to the tables. 287 bool covered = false; 288 for (int cr = 0; cr < _cur_covered_regions; cr++) { 289 if (_committed[cr].contains(new_end - 1)) { 290 covered = true; 291 break; 292 } 293 } 294 assert(covered, "Card for end of new region not committed"); 295 #endif 296 297 // The default of 0 is not necessarily clean cards. 298 CardValue* entry; 299 if (old_region.last() < _whole_heap.start()) { 300 entry = byte_for(_whole_heap.start()); 301 } else { 302 entry = byte_after(old_region.last()); 303 } 304 assert(index_for(new_region.last()) < _guard_index, 305 "The guard card will be overwritten"); 306 // This line commented out cleans the newly expanded region and 307 // not the aligned up expanded region. 308 // CardValue* const end = byte_after(new_region.last()); 309 CardValue* const end = (CardValue*) new_end_for_commit; 310 assert((end >= byte_after(new_region.last())) || collided || guarded, 311 "Expect to be beyond new region unless impacting another region"); 312 // do nothing if we resized downward. 313 #ifdef ASSERT 314 for (int ri = 0; ri < _cur_covered_regions; ri++) { 315 if (ri != ind) { 316 // The end of the new committed region should not 317 // be in any existing region unless it matches 318 // the start of the next region. 319 assert(!_committed[ri].contains(end) || 320 (_committed[ri].start() == (HeapWord*) end), 321 "Overlapping committed regions"); 322 } 323 } 324 #endif 325 if (entry < end) { 326 memset(entry, clean_card, pointer_delta(end, entry, sizeof(CardValue))); 327 } 328 } 329 // In any case, the covered size changes. 330 _covered[ind].set_word_size(new_region.word_size()); 331 332 log_trace(gc, barrier)("CardTable::resize_covered_region: "); 333 log_trace(gc, barrier)(" _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT, 334 ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last())); 335 log_trace(gc, barrier)(" _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT, 336 ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last())); 337 log_trace(gc, barrier)(" byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT, 338 p2i(byte_for(_covered[ind].start())), p2i(byte_for(_covered[ind].last()))); 339 log_trace(gc, barrier)(" addr_for(start): " INTPTR_FORMAT " addr_for(last): " INTPTR_FORMAT, 340 p2i(addr_for((CardValue*) _committed[ind].start())), p2i(addr_for((CardValue*) _committed[ind].last()))); 341 342 // Touch the last card of the covered region to show that it 343 // is committed (or SEGV). 344 debug_only((void) (*byte_for(_covered[ind].last()));) 345 debug_only(verify_guard();) 346 } 347 348 // Note that these versions are precise! The scanning code has to handle the 349 // fact that the write barrier may be either precise or imprecise. 350 void CardTable::dirty_MemRegion(MemRegion mr) { 351 assert(align_down(mr.start(), HeapWordSize) == mr.start(), "Unaligned start"); 352 assert(align_up (mr.end(), HeapWordSize) == mr.end(), "Unaligned end" ); 353 CardValue* cur = byte_for(mr.start()); 354 CardValue* last = byte_after(mr.last()); 355 while (cur < last) { 356 *cur = dirty_card; 357 cur++; 358 } 359 } 360 361 void CardTable::clear_MemRegion(MemRegion mr) { 362 // Be conservative: only clean cards entirely contained within the 363 // region. 364 CardValue* cur; 365 if (mr.start() == _whole_heap.start()) { 366 cur = byte_for(mr.start()); 367 } else { 368 assert(mr.start() > _whole_heap.start(), "mr is not covered."); 369 cur = byte_after(mr.start() - 1); 370 } 371 CardValue* last = byte_after(mr.last()); 372 memset(cur, clean_card, pointer_delta(last, cur, sizeof(CardValue))); 373 } 374 375 void CardTable::clear(MemRegion mr) { 376 for (int i = 0; i < _cur_covered_regions; i++) { 377 MemRegion mri = mr.intersection(_covered[i]); 378 if (!mri.is_empty()) clear_MemRegion(mri); 379 } 380 } 381 382 void CardTable::dirty(MemRegion mr) { 383 CardValue* first = byte_for(mr.start()); 384 CardValue* last = byte_after(mr.last()); 385 memset(first, dirty_card, last-first); 386 } 387 388 // Unlike several other card table methods, dirty_card_iterate() 389 // iterates over dirty cards ranges in increasing address order. 390 void CardTable::dirty_card_iterate(MemRegion mr, MemRegionClosure* cl) { 391 for (int i = 0; i < _cur_covered_regions; i++) { 392 MemRegion mri = mr.intersection(_covered[i]); 393 if (!mri.is_empty()) { 394 CardValue *cur_entry, *next_entry, *limit; 395 for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last()); 396 cur_entry <= limit; 397 cur_entry = next_entry) { 398 next_entry = cur_entry + 1; 399 if (*cur_entry == dirty_card) { 400 size_t dirty_cards; 401 // Accumulate maximal dirty card range, starting at cur_entry 402 for (dirty_cards = 1; 403 next_entry <= limit && *next_entry == dirty_card; 404 dirty_cards++, next_entry++); 405 MemRegion cur_cards(addr_for(cur_entry), 406 dirty_cards*_card_size_in_words); 407 cl->do_MemRegion(cur_cards); 408 } 409 } 410 } 411 } 412 } 413 414 MemRegion CardTable::dirty_card_range_after_reset(MemRegion mr, 415 bool reset, 416 int reset_val) { 417 for (int i = 0; i < _cur_covered_regions; i++) { 418 MemRegion mri = mr.intersection(_covered[i]); 419 if (!mri.is_empty()) { 420 CardValue* cur_entry, *next_entry, *limit; 421 for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last()); 422 cur_entry <= limit; 423 cur_entry = next_entry) { 424 next_entry = cur_entry + 1; 425 if (*cur_entry == dirty_card) { 426 size_t dirty_cards; 427 // Accumulate maximal dirty card range, starting at cur_entry 428 for (dirty_cards = 1; 429 next_entry <= limit && *next_entry == dirty_card; 430 dirty_cards++, next_entry++); 431 MemRegion cur_cards(addr_for(cur_entry), 432 dirty_cards * _card_size_in_words); 433 if (reset) { 434 for (size_t i = 0; i < dirty_cards; i++) { 435 cur_entry[i] = reset_val; 436 } 437 } 438 return cur_cards; 439 } 440 } 441 } 442 } 443 return MemRegion(mr.end(), mr.end()); 444 } 445 446 uintx CardTable::ct_max_alignment_constraint() { 447 // Calculate maximum alignment using GCCardSizeInBytes as card_size hasn't been set yet 448 return GCCardSizeInBytes * os::vm_page_size(); 449 } 450 451 void CardTable::verify_guard() { 452 // For product build verification 453 guarantee(_byte_map[_guard_index] == last_card, 454 "card table guard has been modified"); 455 } 456 457 void CardTable::invalidate(MemRegion mr) { 458 assert(align_down(mr.start(), HeapWordSize) == mr.start(), "Unaligned start"); 459 assert(align_up (mr.end(), HeapWordSize) == mr.end(), "Unaligned end" ); 460 for (int i = 0; i < _cur_covered_regions; i++) { 461 MemRegion mri = mr.intersection(_covered[i]); 462 if (!mri.is_empty()) dirty_MemRegion(mri); 463 } 464 } 465 466 void CardTable::verify() { 467 verify_guard(); 468 } 469 470 #ifndef PRODUCT 471 void CardTable::verify_region(MemRegion mr, CardValue val, bool val_equals) { 472 CardValue* start = byte_for(mr.start()); 473 CardValue* end = byte_for(mr.last()); 474 bool failures = false; 475 for (CardValue* curr = start; curr <= end; ++curr) { 476 CardValue curr_val = *curr; 477 bool failed = (val_equals) ? (curr_val != val) : (curr_val == val); 478 if (failed) { 479 if (!failures) { 480 log_error(gc, verify)("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end)); 481 log_error(gc, verify)("== %sexpecting value: %d", (val_equals) ? "" : "not ", val); 482 failures = true; 483 } 484 log_error(gc, verify)("== card " PTR_FORMAT " [" PTR_FORMAT "," PTR_FORMAT "], val: %d", 485 p2i(curr), p2i(addr_for(curr)), 486 p2i((HeapWord*) (((size_t) addr_for(curr)) + _card_size)), 487 (int) curr_val); 488 } 489 } 490 guarantee(!failures, "there should not have been any failures"); 491 } 492 493 void CardTable::verify_not_dirty_region(MemRegion mr) { 494 verify_region(mr, dirty_card, false /* val_equals */); 495 } 496 497 void CardTable::verify_dirty_region(MemRegion mr) { 498 verify_region(mr, dirty_card, true /* val_equals */); 499 } 500 #endif 501 502 void CardTable::print_on(outputStream* st) const { 503 st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] _byte_map_base: " INTPTR_FORMAT, 504 p2i(_byte_map), p2i(_byte_map + _byte_map_size), p2i(_byte_map_base)); 505 }