rev 58060 : [mq]: 8238999-iklam-review

   1 /*
   2  * Copyright (c) 2000, 2018, 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/space.inline.hpp"
  29 #include "logging/log.hpp"
  30 #include "memory/virtualspace.hpp"
  31 #include "runtime/java.hpp"
  32 #include "runtime/os.hpp"
  33 #include "services/memTracker.hpp"
  34 #include "utilities/align.hpp"
  35 
  36 size_t CardTable::compute_byte_map_size() {
  37   assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,
  38                                         "uninitialized, check declaration order");
  39   assert(_page_size != 0, "uninitialized, check declaration order");
  40   const size_t granularity = os::vm_allocation_granularity();
  41   return align_up(_guard_index + 1, MAX2(_page_size, granularity));
  42 }
  43 
  44 CardTable::CardTable(MemRegion whole_heap, bool conc_scan) :
  45   _scanned_concurrently(conc_scan),
  46   _whole_heap(whole_heap),
  47   _guard_index(0),
  48   _last_valid_index(0),
  49   _page_size(os::vm_page_size()),
  50   _byte_map_size(0),
  51   _byte_map(NULL),
  52   _byte_map_base(NULL),
  53   _cur_covered_regions(0),
  54   _covered(NULL),
  55   _committed(NULL),
  56   _guard_region()
  57 {
  58   assert((uintptr_t(_whole_heap.start())  & (card_size - 1))  == 0, "heap must start at card boundary");
  59   assert((uintptr_t(_whole_heap.end()) & (card_size - 1))  == 0, "heap must end at card boundary");
  60 
  61   assert(card_size <= 512, "card_size must be less than 512"); // why?
  62 
  63   _covered = new MemRegion[_max_covered_regions];
  64   if (_covered == NULL) {
  65     vm_exit_during_initialization("Could not allocate card table covered region set.");
  66   }
  67 }
  68 
  69 CardTable::~CardTable() {
  70   if (_covered) {
  71     delete[] _covered;
  72     _covered = NULL;
  73   }
  74   if (_committed) {
  75     delete[] _committed;
  76     _committed = NULL;
  77   }
  78 }
  79 
  80 void CardTable::initialize() {
  81   _guard_index = cards_required(_whole_heap.word_size()) - 1;
  82   _last_valid_index = _guard_index - 1;
  83 
  84   _byte_map_size = compute_byte_map_size();
  85 
  86   HeapWord* low_bound  = _whole_heap.start();
  87   HeapWord* high_bound = _whole_heap.end();
  88 
  89   _cur_covered_regions = 0;
  90   _committed = new MemRegion[_max_covered_regions];
  91   if (_committed == NULL) {
  92     vm_exit_during_initialization("Could not allocate card table committed region set.");
  93   }
  94 
  95   const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :
  96     MAX2(_page_size, (size_t) os::vm_allocation_granularity());
  97   ReservedSpace heap_rs(_byte_map_size, rs_align, false);
  98 
  99   MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);
 100 
 101   os::trace_page_sizes("Card Table", _guard_index + 1, _guard_index + 1,
 102                        _page_size, heap_rs.base(), heap_rs.size());
 103   if (!heap_rs.is_reserved()) {
 104     vm_exit_during_initialization("Could not reserve enough space for the "
 105                                   "card marking array");
 106   }
 107 
 108   // The assembler store_check code will do an unsigned shift of the oop,
 109   // then add it to _byte_map_base, i.e.
 110   //
 111   //   _byte_map = _byte_map_base + (uintptr_t(low_bound) >> card_shift)
 112   _byte_map = (CardValue*) heap_rs.base();
 113   _byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
 114   assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
 115   assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
 116 
 117   CardValue* guard_card = &_byte_map[_guard_index];
 118   HeapWord* guard_page = align_down((HeapWord*)guard_card, _page_size);
 119   _guard_region = MemRegion(guard_page, _page_size);
 120   os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size,
 121                             !ExecMem, "card table last card");
 122   *guard_card = last_card;
 123 
 124   log_trace(gc, barrier)("CardTable::CardTable: ");
 125   log_trace(gc, barrier)("    &_byte_map[0]: " INTPTR_FORMAT "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
 126                   p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index]));
 127   log_trace(gc, barrier)("    _byte_map_base: " INTPTR_FORMAT, p2i(_byte_map_base));
 128 }
 129 
 130 int CardTable::find_covering_region_by_base(HeapWord* base) {
 131   int i;
 132   for (i = 0; i < _cur_covered_regions; i++) {
 133     if (_covered[i].start() == base) return i;
 134     if (_covered[i].start() > base) break;
 135   }
 136   // If we didn't find it, create a new one.
 137   assert(_cur_covered_regions < _max_covered_regions,
 138          "too many covered regions");
 139   // Move the ones above up, to maintain sorted order.
 140   for (int j = _cur_covered_regions; j > i; j--) {
 141     _covered[j] = _covered[j-1];
 142     _committed[j] = _committed[j-1];
 143   }
 144   int res = i;
 145   _cur_covered_regions++;
 146   _covered[res].set_start(base);
 147   _covered[res].set_word_size(0);
 148   CardValue* ct_start = byte_for(base);
 149   HeapWord* ct_start_aligned = align_down((HeapWord*)ct_start, _page_size);
 150   _committed[res].set_start(ct_start_aligned);
 151   _committed[res].set_word_size(0);
 152   return res;
 153 }
 154 
 155 int CardTable::find_covering_region_containing(HeapWord* addr) {
 156   for (int i = 0; i < _cur_covered_regions; i++) {
 157     if (_covered[i].contains(addr)) {
 158       return i;
 159     }
 160   }
 161   assert(0, "address outside of heap?");
 162   return -1;
 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         // It is not safe to uncommit cards if the boundary between
 272         // the generations is moving.  A shrink can uncommit cards
 273         // owned by generation A but being used by generation B.
 274         if (!UseAdaptiveGCBoundary) {
 275           if (!os::uncommit_memory((char*)uncommit_region.start(),
 276                                    uncommit_region.byte_size())) {
 277             assert(false, "Card table contraction failed");
 278             // The call failed so don't change the end of the
 279             // committed region.  This is better than taking the
 280             // VM down.
 281             new_end_aligned = _committed[ind].end();
 282           }
 283         } else {
 284           new_end_aligned = _committed[ind].end();
 285         }
 286       }
 287     }
 288     // In any case, we can reset the end of the current committed entry.
 289     _committed[ind].set_end(new_end_aligned);
 290 
 291 #ifdef ASSERT
 292     // Check that the last card in the new region is committed according
 293     // to the tables.
 294     bool covered = false;
 295     for (int cr = 0; cr < _cur_covered_regions; cr++) {
 296       if (_committed[cr].contains(new_end - 1)) {
 297         covered = true;
 298         break;
 299       }
 300     }
 301     assert(covered, "Card for end of new region not committed");
 302 #endif
 303 
 304     // The default of 0 is not necessarily clean cards.
 305     CardValue* entry;
 306     if (old_region.last() < _whole_heap.start()) {
 307       entry = byte_for(_whole_heap.start());
 308     } else {
 309       entry = byte_after(old_region.last());
 310     }
 311     assert(index_for(new_region.last()) <  _guard_index,
 312       "The guard card will be overwritten");
 313     // This line commented out cleans the newly expanded region and
 314     // not the aligned up expanded region.
 315     // CardValue* const end = byte_after(new_region.last());
 316     CardValue* const end = (CardValue*) new_end_for_commit;
 317     assert((end >= byte_after(new_region.last())) || collided || guarded,
 318       "Expect to be beyond new region unless impacting another region");
 319     // do nothing if we resized downward.
 320 #ifdef ASSERT
 321     for (int ri = 0; ri < _cur_covered_regions; ri++) {
 322       if (ri != ind) {
 323         // The end of the new committed region should not
 324         // be in any existing region unless it matches
 325         // the start of the next region.
 326         assert(!_committed[ri].contains(end) ||
 327                (_committed[ri].start() == (HeapWord*) end),
 328                "Overlapping committed regions");
 329       }
 330     }
 331 #endif
 332     if (entry < end) {
 333       memset(entry, clean_card, pointer_delta(end, entry, sizeof(CardValue)));
 334     }
 335   }
 336   // In any case, the covered size changes.
 337   _covered[ind].set_word_size(new_region.word_size());
 338 
 339   log_trace(gc, barrier)("CardTable::resize_covered_region: ");
 340   log_trace(gc, barrier)("    _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT,
 341                          ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last()));
 342   log_trace(gc, barrier)("    _committed[%d].start(): " INTPTR_FORMAT "  _committed[%d].last(): " INTPTR_FORMAT,
 343                          ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last()));
 344   log_trace(gc, barrier)("    byte_for(start): " INTPTR_FORMAT "  byte_for(last): " INTPTR_FORMAT,
 345                          p2i(byte_for(_covered[ind].start())),  p2i(byte_for(_covered[ind].last())));
 346   log_trace(gc, barrier)("    addr_for(start): " INTPTR_FORMAT "  addr_for(last): " INTPTR_FORMAT,
 347                          p2i(addr_for((CardValue*) _committed[ind].start())),  p2i(addr_for((CardValue*) _committed[ind].last())));
 348 
 349   // Touch the last card of the covered region to show that it
 350   // is committed (or SEGV).
 351   debug_only((void) (*byte_for(_covered[ind].last()));)
 352   debug_only(verify_guard();)
 353 }
 354 
 355 // Note that these versions are precise!  The scanning code has to handle the
 356 // fact that the write barrier may be either precise or imprecise.
 357 void CardTable::dirty_MemRegion(MemRegion mr) {
 358   assert(align_down(mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
 359   assert(align_up  (mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );
 360   CardValue* cur  = byte_for(mr.start());
 361   CardValue* last = byte_after(mr.last());
 362   while (cur < last) {
 363     *cur = dirty_card;
 364     cur++;
 365   }
 366 }
 367 
 368 void CardTable::clear_MemRegion(MemRegion mr) {
 369   // Be conservative: only clean cards entirely contained within the
 370   // region.
 371   CardValue* cur;
 372   if (mr.start() == _whole_heap.start()) {
 373     cur = byte_for(mr.start());
 374   } else {
 375     assert(mr.start() > _whole_heap.start(), "mr is not covered.");
 376     cur = byte_after(mr.start() - 1);
 377   }
 378   CardValue* last = byte_after(mr.last());
 379   memset(cur, clean_card, pointer_delta(last, cur, sizeof(CardValue)));
 380 }
 381 
 382 void CardTable::clear(MemRegion mr) {
 383   for (int i = 0; i < _cur_covered_regions; i++) {
 384     MemRegion mri = mr.intersection(_covered[i]);
 385     if (!mri.is_empty()) clear_MemRegion(mri);
 386   }
 387 }
 388 
 389 void CardTable::dirty(MemRegion mr) {
 390   CardValue* first = byte_for(mr.start());
 391   CardValue* last  = byte_after(mr.last());
 392   memset(first, dirty_card, last-first);
 393 }
 394 
 395 // Unlike several other card table methods, dirty_card_iterate()
 396 // iterates over dirty cards ranges in increasing address order.
 397 void CardTable::dirty_card_iterate(MemRegion mr, MemRegionClosure* cl) {
 398   for (int i = 0; i < _cur_covered_regions; i++) {
 399     MemRegion mri = mr.intersection(_covered[i]);
 400     if (!mri.is_empty()) {
 401       CardValue *cur_entry, *next_entry, *limit;
 402       for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
 403            cur_entry <= limit;
 404            cur_entry  = next_entry) {
 405         next_entry = cur_entry + 1;
 406         if (*cur_entry == dirty_card) {
 407           size_t dirty_cards;
 408           // Accumulate maximal dirty card range, starting at cur_entry
 409           for (dirty_cards = 1;
 410                next_entry <= limit && *next_entry == dirty_card;
 411                dirty_cards++, next_entry++);
 412           MemRegion cur_cards(addr_for(cur_entry),
 413                               dirty_cards*card_size_in_words);
 414           cl->do_MemRegion(cur_cards);
 415         }
 416       }
 417     }
 418   }
 419 }
 420 
 421 MemRegion CardTable::dirty_card_range_after_reset(MemRegion mr,
 422                                                   bool reset,
 423                                                   int reset_val) {
 424   for (int i = 0; i < _cur_covered_regions; i++) {
 425     MemRegion mri = mr.intersection(_covered[i]);
 426     if (!mri.is_empty()) {
 427       CardValue* cur_entry, *next_entry, *limit;
 428       for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
 429            cur_entry <= limit;
 430            cur_entry  = next_entry) {
 431         next_entry = cur_entry + 1;
 432         if (*cur_entry == dirty_card) {
 433           size_t dirty_cards;
 434           // Accumulate maximal dirty card range, starting at cur_entry
 435           for (dirty_cards = 1;
 436                next_entry <= limit && *next_entry == dirty_card;
 437                dirty_cards++, next_entry++);
 438           MemRegion cur_cards(addr_for(cur_entry),
 439                               dirty_cards*card_size_in_words);
 440           if (reset) {
 441             for (size_t i = 0; i < dirty_cards; i++) {
 442               cur_entry[i] = reset_val;
 443             }
 444           }
 445           return cur_cards;
 446         }
 447       }
 448     }
 449   }
 450   return MemRegion(mr.end(), mr.end());
 451 }
 452 
 453 uintx CardTable::ct_max_alignment_constraint() {
 454   return card_size * os::vm_page_size();
 455 }
 456 
 457 void CardTable::verify_guard() {
 458   // For product build verification
 459   guarantee(_byte_map[_guard_index] == last_card,
 460             "card table guard has been modified");
 461 }
 462 
 463 void CardTable::invalidate(MemRegion mr) {
 464   assert(align_down(mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
 465   assert(align_up  (mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );
 466   for (int i = 0; i < _cur_covered_regions; i++) {
 467     MemRegion mri = mr.intersection(_covered[i]);
 468     if (!mri.is_empty()) dirty_MemRegion(mri);
 469   }
 470 }
 471 
 472 void CardTable::verify() {
 473   verify_guard();
 474 }
 475 
 476 #ifndef PRODUCT
 477 void CardTable::verify_region(MemRegion mr, CardValue val, bool val_equals) {
 478   CardValue* start    = byte_for(mr.start());
 479   CardValue* end      = byte_for(mr.last());
 480   bool failures = false;
 481   for (CardValue* curr = start; curr <= end; ++curr) {
 482     CardValue curr_val = *curr;
 483     bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);
 484     if (failed) {
 485       if (!failures) {
 486         log_error(gc, verify)("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end));
 487         log_error(gc, verify)("==   %sexpecting value: %d", (val_equals) ? "" : "not ", val);
 488         failures = true;
 489       }
 490       log_error(gc, verify)("==   card " PTR_FORMAT " [" PTR_FORMAT "," PTR_FORMAT "], val: %d",
 491                             p2i(curr), p2i(addr_for(curr)),
 492                             p2i((HeapWord*) (((size_t) addr_for(curr)) + card_size)),
 493                             (int) curr_val);
 494     }
 495   }
 496   guarantee(!failures, "there should not have been any failures");
 497 }
 498 
 499 void CardTable::verify_not_dirty_region(MemRegion mr) {
 500   verify_region(mr, dirty_card, false /* val_equals */);
 501 }
 502 
 503 void CardTable::verify_dirty_region(MemRegion mr) {
 504   verify_region(mr, dirty_card, true /* val_equals */);
 505 }
 506 #endif
 507 
 508 void CardTable::print_on(outputStream* st) const {
 509   st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] _byte_map_base: " INTPTR_FORMAT,
 510                p2i(_byte_map), p2i(_byte_map + _byte_map_size), p2i(_byte_map_base));
 511 }
--- EOF ---