/*

 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc/shared/cardTable.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/space.inline.hpp"

#include "logging/log.hpp"

#include "memory/virtualspace.hpp"

#include "runtime/java.hpp"

#include "runtime/os.hpp"

#include "services/memTracker.hpp"

#include "utilities/align.hpp"

size_t CardTable::compute_byte_map_size() {

  assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,

                                        "uninitialized, check declaration order");

  assert(_page_size != 0, "uninitialized, check declaration order");

  const size_t granularity = os::vm_allocation_granularity();

  return align_up(_guard_index + 1, MAX2(_page_size, granularity));

}

CardTable::CardTable(MemRegion whole_heap, bool conc_scan) :

  _scanned_concurrently(conc_scan),

  _whole_heap(whole_heap),

  _guard_index(0),

  _last_valid_index(0),

  _page_size(os::vm_page_size()),

  _byte_map_size(0),

  _covered(NULL),

  _committed(NULL),

{

  assert((uintptr_t(_whole_heap.start())  & (card_size - 1))  == 0, "heap must start at card boundary");

  assert((uintptr_t(_whole_heap.end()) & (card_size - 1))  == 0, "heap must end at card boundary");

  assert(card_size <= 512, "card_size must be less than 512"); // why?

  _covered   = new MemRegion[_max_covered_regions];

  if (_covered == NULL) {

    vm_exit_during_initialization("Could not allocate card table covered region set.");

  }

}

CardTable::~CardTable() {

  if (_covered) {

    delete[] _covered;

    _covered = NULL;

  }

  if (_committed) {

    delete[] _committed;

    _committed = NULL;

  }

}

void CardTable::initialize() {

  _guard_index = cards_required(_whole_heap.word_size()) - 1;

  _last_valid_index = _guard_index - 1;

  _byte_map_size = compute_byte_map_size();

  HeapWord* low_bound  = _whole_heap.start();

  HeapWord* high_bound = _whole_heap.end();

  _cur_covered_regions = 0;

  _committed = new MemRegion[_max_covered_regions];

  if (_committed == NULL) {

    vm_exit_during_initialization("Could not allocate card table committed region set.");

  }

  const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :

    MAX2(_page_size, (size_t) os::vm_allocation_granularity());

  ReservedSpace heap_rs(_byte_map_size, rs_align, false);

  MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);

  os::trace_page_sizes("Card Table", _guard_index + 1, _guard_index + 1,

                       _page_size, heap_rs.base(), heap_rs.size());

  if (!heap_rs.is_reserved()) {

    vm_exit_during_initialization("Could not reserve enough space for the "

                                  "card marking array");

  }

  // The assembler store_check code will do an unsigned shift of the oop,

  // then add it to _byte_map_base, i.e.

  //

  //   _byte_map = _byte_map_base + (uintptr_t(low_bound) >> card_shift)

  _byte_map = (jbyte*) heap_rs.base();

  _byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);

  assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");

  assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");

  jbyte* guard_card = &_byte_map[_guard_index];

  HeapWord* guard_page = align_down((HeapWord*)guard_card, _page_size);

  _guard_region = MemRegion(guard_page, _page_size);

  os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size,

                            !ExecMem, "card table last card");

  *guard_card = last_card;

  log_trace(gc, barrier)("CardTable::CardTable: ");

  log_trace(gc, barrier)("    &_byte_map[0]: " INTPTR_FORMAT "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,

                  p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index]));

  log_trace(gc, barrier)("    _byte_map_base: " INTPTR_FORMAT, p2i(_byte_map_base));

}

int CardTable::find_covering_region_by_base(HeapWord* base) {

  int i;

  for (i = 0; i < _cur_covered_regions; i++) {

    if (_covered[i].start() == base) return i;

    if (_covered[i].start() > base) break;

  }

  // If we didn't find it, create a new one.

  assert(_cur_covered_regions < _max_covered_regions,

         "too many covered regions");

  // Move the ones above up, to maintain sorted order.

  for (int j = _cur_covered_regions; j > i; j--) {

    _covered[j] = _covered[j-1];

    _committed[j] = _committed[j-1];

  }

  int res = i;

  _cur_covered_regions++;

  _covered[res].set_start(base);

  _covered[res].set_word_size(0);

  jbyte* ct_start = byte_for(base);

  HeapWord* ct_start_aligned = align_down((HeapWord*)ct_start, _page_size);

  _committed[res].set_start(ct_start_aligned);

  _committed[res].set_word_size(0);

  return res;

}

int CardTable::find_covering_region_containing(HeapWord* addr) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    if (_covered[i].contains(addr)) {

      return i;

    }

  }

  assert(0, "address outside of heap?");

  return -1;

}

HeapWord* CardTable::largest_prev_committed_end(int ind) const {

  HeapWord* max_end = NULL;

  for (int j = 0; j < ind; j++) {

    HeapWord* this_end = _committed[j].end();

    if (this_end > max_end) max_end = this_end;

  }

  return max_end;

}

MemRegion CardTable::committed_unique_to_self(int self, MemRegion mr) const {

  MemRegion result = mr;

  for (int r = 0; r < _cur_covered_regions; r += 1) {

    if (r != self) {

      result = result.minus(_committed[r]);

    }

  }

  // Never include the guard page.

  result = result.minus(_guard_region);

  return result;

}

void CardTable::resize_covered_region(MemRegion new_region) {

  // We don't change the start of a region, only the end.

  assert(_whole_heap.contains(new_region),

           "attempt to cover area not in reserved area");

  debug_only(verify_guard();)

  // collided is true if the expansion would push into another committed region

  debug_only(bool collided = false;)

  int const ind = find_covering_region_by_base(new_region.start());

  MemRegion const old_region = _covered[ind];

  assert(old_region.start() == new_region.start(), "just checking");

  if (new_region.word_size() != old_region.word_size()) {

    // Commit new or uncommit old pages, if necessary.

    MemRegion cur_committed = _committed[ind];

    // Extend the end of this _committed region

    // to cover the end of any lower _committed regions.

    // This forms overlapping regions, but never interior regions.

    HeapWord* const max_prev_end = largest_prev_committed_end(ind);

    if (max_prev_end > cur_committed.end()) {

      cur_committed.set_end(max_prev_end);

    }

    // Align the end up to a page size (starts are already aligned).

    HeapWord* new_end = (HeapWord*) byte_after(new_region.last());

    HeapWord* new_end_aligned = align_up(new_end, _page_size);

    assert(new_end_aligned >= new_end, "align up, but less");

    // Check the other regions (excludes "ind") to ensure that

    // the new_end_aligned does not intrude onto the committed

    // space of another region.

    int ri = 0;

    for (ri = ind + 1; ri < _cur_covered_regions; ri++) {

      if (new_end_aligned > _committed[ri].start()) {

        assert(new_end_aligned <= _committed[ri].end(),

               "An earlier committed region can't cover a later committed region");

        // Any region containing the new end

        // should start at or beyond the region found (ind)

        // for the new end (committed regions are not expected to

        // be proper subsets of other committed regions).

        assert(_committed[ri].start() >= _committed[ind].start(),

               "New end of committed region is inconsistent");

        new_end_aligned = _committed[ri].start();

        // new_end_aligned can be equal to the start of its

        // committed region (i.e., of "ind") if a second

        // region following "ind" also start at the same location

        // as "ind".

        assert(new_end_aligned >= _committed[ind].start(),

          "New end of committed region is before start");

        debug_only(collided = true;)

        // Should only collide with 1 region

        break;

      }

    }

#ifdef ASSERT

    for (++ri; ri < _cur_covered_regions; ri++) {

      assert(!_committed[ri].contains(new_end_aligned),

        "New end of committed region is in a second committed region");

    }

#endif

    // The guard page is always committed and should not be committed over.

    // "guarded" is used for assertion checking below and recalls the fact

    // that the would-be end of the new committed region would have

    // penetrated the guard page.

    HeapWord* new_end_for_commit = new_end_aligned;

    DEBUG_ONLY(bool guarded = false;)

    if (new_end_for_commit > _guard_region.start()) {

      new_end_for_commit = _guard_region.start();

      DEBUG_ONLY(guarded = true;)

    }

    if (new_end_for_commit > cur_committed.end()) {

      // Must commit new pages.

      MemRegion const new_committed =

        MemRegion(cur_committed.end(), new_end_for_commit);

      assert(!new_committed.is_empty(), "Region should not be empty here");

      os::commit_memory_or_exit((char*)new_committed.start(),

                                new_committed.byte_size(), _page_size,

                                !ExecMem, "card table expansion");

    // Use new_end_aligned (as opposed to new_end_for_commit) because

    // the cur_committed region may include the guard region.

    } else if (new_end_aligned < cur_committed.end()) {

      // Must uncommit pages.

      MemRegion const uncommit_region =

        committed_unique_to_self(ind, MemRegion(new_end_aligned,

                                                cur_committed.end()));

      if (!uncommit_region.is_empty()) {

        // It is not safe to uncommit cards if the boundary between

        // the generations is moving.  A shrink can uncommit cards

        // owned by generation A but being used by generation B.

        if (!UseAdaptiveGCBoundary) {

          if (!os::uncommit_memory((char*)uncommit_region.start(),

                                   uncommit_region.byte_size())) {

            assert(false, "Card table contraction failed");

            // The call failed so don't change the end of the

            // committed region.  This is better than taking the

            // VM down.

            new_end_aligned = _committed[ind].end();

          }

        } else {

          new_end_aligned = _committed[ind].end();

        }

      }

    }

    // In any case, we can reset the end of the current committed entry.

    _committed[ind].set_end(new_end_aligned);

#ifdef ASSERT

    // Check that the last card in the new region is committed according

    // to the tables.

    bool covered = false;

    for (int cr = 0; cr < _cur_covered_regions; cr++) {

      if (_committed[cr].contains(new_end - 1)) {

        covered = true;

        break;

      }

    }

    assert(covered, "Card for end of new region not committed");

#endif

    // The default of 0 is not necessarily clean cards.

    jbyte* entry;

    if (old_region.last() < _whole_heap.start()) {

      entry = byte_for(_whole_heap.start());

    } else {

      entry = byte_after(old_region.last());

    }

    assert(index_for(new_region.last()) <  _guard_index,

      "The guard card will be overwritten");

    // This line commented out cleans the newly expanded region and

    // not the aligned up expanded region.

    // jbyte* const end = byte_after(new_region.last());

    jbyte* const end = (jbyte*) new_end_for_commit;

    assert((end >= byte_after(new_region.last())) || collided || guarded,

      "Expect to be beyond new region unless impacting another region");

    // do nothing if we resized downward.

#ifdef ASSERT

    for (int ri = 0; ri < _cur_covered_regions; ri++) {

      if (ri != ind) {

        // The end of the new committed region should not

        // be in any existing region unless it matches

        // the start of the next region.

        assert(!_committed[ri].contains(end) ||

               (_committed[ri].start() == (HeapWord*) end),

               "Overlapping committed regions");

      }

    }

#endif

    if (entry < end) {

      memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));

    }

  }

  // In any case, the covered size changes.

  _covered[ind].set_word_size(new_region.word_size());

  log_trace(gc, barrier)("CardTable::resize_covered_region: ");

  log_trace(gc, barrier)("    _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT,

                         ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last()));

  log_trace(gc, barrier)("    _committed[%d].start(): " INTPTR_FORMAT "  _committed[%d].last(): " INTPTR_FORMAT,

                         ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last()));

  log_trace(gc, barrier)("    byte_for(start): " INTPTR_FORMAT "  byte_for(last): " INTPTR_FORMAT,

                         p2i(byte_for(_covered[ind].start())),  p2i(byte_for(_covered[ind].last())));

  log_trace(gc, barrier)("    addr_for(start): " INTPTR_FORMAT "  addr_for(last): " INTPTR_FORMAT,

                         p2i(addr_for((jbyte*) _committed[ind].start())),  p2i(addr_for((jbyte*) _committed[ind].last())));

  // Touch the last card of the covered region to show that it

  // is committed (or SEGV).

  debug_only((void) (*byte_for(_covered[ind].last()));)

  debug_only(verify_guard();)

}

// Note that these versions are precise!  The scanning code has to handle the

// fact that the write barrier may be either precise or imprecise.

void CardTable::dirty_MemRegion(MemRegion mr) {

  assert(align_down(mr.start(), HeapWordSize) == mr.start(), "Unaligned start");

  assert(align_up  (mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );

  jbyte* cur  = byte_for(mr.start());

  jbyte* last = byte_after(mr.last());

  while (cur < last) {

    *cur = dirty_card;

    cur++;

  }

}

void CardTable::clear_MemRegion(MemRegion mr) {

  // Be conservative: only clean cards entirely contained within the

  // region.

  jbyte* cur;

  if (mr.start() == _whole_heap.start()) {

    cur = byte_for(mr.start());

  } else {

    assert(mr.start() > _whole_heap.start(), "mr is not covered.");

    cur = byte_after(mr.start() - 1);

  }

  jbyte* last = byte_after(mr.last());

  memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte)));

}

void CardTable::clear(MemRegion mr) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) clear_MemRegion(mri);

  }

}

void CardTable::dirty(MemRegion mr) {

  jbyte* first = byte_for(mr.start());

  jbyte* last  = byte_after(mr.last());

  memset(first, dirty_card, last-first);

}

// Unlike several other card table methods, dirty_card_iterate()

// iterates over dirty cards ranges in increasing address order.

void CardTable::dirty_card_iterate(MemRegion mr, MemRegionClosure* cl) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) {

      jbyte *cur_entry, *next_entry, *limit;

      for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());

           cur_entry <= limit;

           cur_entry  = next_entry) {

        next_entry = cur_entry + 1;

        if (*cur_entry == dirty_card) {

          size_t dirty_cards;

          // Accumulate maximal dirty card range, starting at cur_entry

          for (dirty_cards = 1;

               next_entry <= limit && *next_entry == dirty_card;

               dirty_cards++, next_entry++);

          MemRegion cur_cards(addr_for(cur_entry),

                              dirty_cards*card_size_in_words);

          cl->do_MemRegion(cur_cards);

        }

      }

    }

  }

}

MemRegion CardTable::dirty_card_range_after_reset(MemRegion mr,

                                                  bool reset,

                                                  int reset_val) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) {

      jbyte* cur_entry, *next_entry, *limit;

      for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());

           cur_entry <= limit;

           cur_entry  = next_entry) {

        next_entry = cur_entry + 1;

        if (*cur_entry == dirty_card) {

          size_t dirty_cards;

          // Accumulate maximal dirty card range, starting at cur_entry

          for (dirty_cards = 1;

               next_entry <= limit && *next_entry == dirty_card;

               dirty_cards++, next_entry++);

          MemRegion cur_cards(addr_for(cur_entry),

                              dirty_cards*card_size_in_words);

          if (reset) {

            for (size_t i = 0; i < dirty_cards; i++) {

              cur_entry[i] = reset_val;

            }

          }

          return cur_cards;

        }

      }

    }

  }

  return MemRegion(mr.end(), mr.end());

}

uintx CardTable::ct_max_alignment_constraint() {

  return card_size * os::vm_page_size();

}

void CardTable::verify_guard() {

  // For product build verification

  guarantee(_byte_map[_guard_index] == last_card,

            "card table guard has been modified");

}

void CardTable::invalidate(MemRegion mr) {

  assert(align_down(mr.start(), HeapWordSize) == mr.start(), "Unaligned start");

  assert(align_up  (mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) dirty_MemRegion(mri);

  }

}

void CardTable::verify() {

  verify_guard();

}

#ifndef PRODUCT

void CardTable::verify_region(MemRegion mr,

                                      jbyte val, bool val_equals) {

  jbyte* start    = byte_for(mr.start());

  jbyte* end      = byte_for(mr.last());

  bool failures = false;

  for (jbyte* curr = start; curr <= end; ++curr) {

    jbyte curr_val = *curr;

    bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);

    if (failed) {

      if (!failures) {

        log_error(gc, verify)("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end));

        log_error(gc, verify)("==   %sexpecting value: %d", (val_equals) ? "" : "not ", val);

        failures = true;

      }

      log_error(gc, verify)("==   card " PTR_FORMAT " [" PTR_FORMAT "," PTR_FORMAT "], val: %d",

                            p2i(curr), p2i(addr_for(curr)),

                            p2i((HeapWord*) (((size_t) addr_for(curr)) + card_size)),

                            (int) curr_val);

    }

  }

  guarantee(!failures, "there should not have been any failures");

}

void CardTable::verify_not_dirty_region(MemRegion mr) {

  verify_region(mr, dirty_card, false /* val_equals */);

}