/* * Copyright (c) 2000, 2015, 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/cardTableModRefBS.inline.hpp" #include "gc/shared/cardTableRS.hpp" #include "gc/shared/collectedHeap.hpp" #include "gc/shared/genCollectedHeap.hpp" #include "gc/shared/space.hpp" #include "gc/shared/space.inline.hpp" #include "memory/allocation.inline.hpp" #include "memory/universe.hpp" #include "memory/virtualspace.hpp" #include "runtime/java.hpp" #include "runtime/mutexLocker.hpp" #include "services/memTracker.hpp" #include "utilities/macros.hpp" #ifdef COMPILER1 #include "c1/c1_LIR.hpp" #include "c1/c1_LIRGenerator.hpp" #endif // This kind of "BarrierSet" allows a "CollectedHeap" to detect and // enumerate ref fields that have been modified (since the last // enumeration.) size_t CardTableModRefBS::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_size_up(_guard_index + 1, MAX2(_page_size, granularity)); } CardTableModRefBS::CardTableModRefBS( MemRegion whole_heap, const BarrierSet::FakeRtti& fake_rtti) : ModRefBarrierSet(fake_rtti.add_tag(BarrierSet::CardTableModRef)), _whole_heap(whole_heap), _guard_index(0), _guard_region(), _last_valid_index(0), _page_size(os::vm_page_size()), _byte_map_size(0), _covered(NULL), _committed(NULL), _cur_covered_regions(0), _byte_map(NULL), byte_map_base(NULL), // LNC functionality _lowest_non_clean(NULL), _lowest_non_clean_chunk_size(NULL), _lowest_non_clean_base_chunk_index(NULL), _last_LNC_resizing_collection(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."); } } void CardTableModRefBS::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]; uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size); _guard_region = MemRegion((HeapWord*)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; _lowest_non_clean = NEW_C_HEAP_ARRAY(CardArr, _max_covered_regions, mtGC); _lowest_non_clean_chunk_size = NEW_C_HEAP_ARRAY(size_t, _max_covered_regions, mtGC); _lowest_non_clean_base_chunk_index = NEW_C_HEAP_ARRAY(uintptr_t, _max_covered_regions, mtGC); _last_LNC_resizing_collection = NEW_C_HEAP_ARRAY(int, _max_covered_regions, mtGC); if (_lowest_non_clean == NULL || _lowest_non_clean_chunk_size == NULL || _lowest_non_clean_base_chunk_index == NULL || _last_LNC_resizing_collection == NULL) vm_exit_during_initialization("couldn't allocate an LNC array."); for (int i = 0; i < _max_covered_regions; i++) { _lowest_non_clean[i] = NULL; _lowest_non_clean_chunk_size[i] = 0; _last_LNC_resizing_collection[i] = -1; } if (TraceCardTableModRefBS) { gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: "); gclog_or_tty->print_cr(" " " &_byte_map[0]: " INTPTR_FORMAT " &_byte_map[_last_valid_index]: " INTPTR_FORMAT, p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index])); gclog_or_tty->print_cr(" " " byte_map_base: " INTPTR_FORMAT, p2i(byte_map_base)); } } CardTableModRefBS::~CardTableModRefBS() { if (_covered) { delete[] _covered; _covered = NULL; } if (_committed) { delete[] _committed; _committed = NULL; } if (_lowest_non_clean) { FREE_C_HEAP_ARRAY(CardArr, _lowest_non_clean); _lowest_non_clean = NULL; } if (_lowest_non_clean_chunk_size) { FREE_C_HEAP_ARRAY(size_t, _lowest_non_clean_chunk_size); _lowest_non_clean_chunk_size = NULL; } if (_lowest_non_clean_base_chunk_index) { FREE_C_HEAP_ARRAY(uintptr_t, _lowest_non_clean_base_chunk_index); _lowest_non_clean_base_chunk_index = NULL; } if (_last_LNC_resizing_collection) { FREE_C_HEAP_ARRAY(int, _last_LNC_resizing_collection); _last_LNC_resizing_collection = NULL; } } int CardTableModRefBS::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); uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size); _committed[res].set_start((HeapWord*)ct_start_aligned); _committed[res].set_word_size(0); return res; } int CardTableModRefBS::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* CardTableModRefBS::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 CardTableModRefBS::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 CardTableModRefBS::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). jbyte* const new_end = byte_after(new_region.last()); HeapWord* new_end_aligned = (HeapWord*) align_size_up((uintptr_t)new_end, _page_size); assert(new_end_aligned >= (HeapWord*) 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()); if (TraceCardTableModRefBS) { gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: "); gclog_or_tty->print_cr(" " " _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT, ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last())); gclog_or_tty->print_cr(" " " _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT, ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last())); gclog_or_tty->print_cr(" " " byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT, p2i(byte_for(_covered[ind].start())), p2i(byte_for(_covered[ind].last()))); gclog_or_tty->print_cr(" " " 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 CardTableModRefBS::write_ref_field_work(void* field, oop newVal, bool release) { inline_write_ref_field(field, newVal, release); } void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr, OopsInGenClosure* cl, CardTableRS* ct) { if (!mr.is_empty()) { // Caller (process_roots()) claims that all GC threads // execute this call. With UseDynamicNumberOfGCThreads now all // active GC threads execute this call. The number of active GC // threads needs to be passed to par_non_clean_card_iterate_work() // to get proper partitioning and termination. // // This is an example of where n_par_threads() is used instead // of workers()->active_workers(). n_par_threads can be set to 0 to // turn off parallelism. For example when this code is called as // part of verification during root processing then n_par_threads() // may have been set to 0. active_workers is not overloaded with // the meaning that it is a switch to disable parallelism and so keeps // the meaning of the number of active gc workers. If parallelism has // not been shut off by setting n_par_threads to 0, then n_par_threads // should be equal to active_workers. When a different mechanism for // shutting off parallelism is used, then active_workers can be used in // place of n_par_threads. int n_threads = GenCollectedHeap::heap()->n_par_threads(); bool is_par = n_threads > 0; if (is_par) { #if INCLUDE_ALL_GCS assert(GenCollectedHeap::heap()->n_par_threads() == GenCollectedHeap::heap()->workers()->active_workers(), "Mismatch"); non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads); #else // INCLUDE_ALL_GCS fatal("Parallel gc not supported here."); #endif // INCLUDE_ALL_GCS } else { // clear_cl finds contiguous dirty ranges of cards to process and clear. DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(), cl->gen_boundary()); ClearNoncleanCardWrapper clear_cl(dcto_cl, ct); clear_cl.do_MemRegion(mr); } } } void CardTableModRefBS::dirty_MemRegion(MemRegion mr) { assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start"); assert((HeapWord*)align_size_up ((uintptr_t)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 CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) { assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start"); assert((HeapWord*)align_size_up ((uintptr_t)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 CardTableModRefBS::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 CardTableModRefBS::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 CardTableModRefBS::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 CardTableModRefBS::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 CardTableModRefBS::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 CardTableModRefBS::ct_max_alignment_constraint() { return card_size * os::vm_page_size(); } void CardTableModRefBS::verify_guard() { // For product build verification guarantee(_byte_map[_guard_index] == last_card, "card table guard has been modified"); } void CardTableModRefBS::verify() { verify_guard(); } #ifndef PRODUCT void CardTableModRefBS::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) { tty->cr(); tty->print_cr("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end)); tty->print_cr("== %sexpecting value: %d", (val_equals) ? "" : "not ", val); failures = true; } tty->print_cr("== 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 CardTableModRefBS::verify_not_dirty_region(MemRegion mr) { verify_region(mr, dirty_card, false /* val_equals */); } void CardTableModRefBS::verify_dirty_region(MemRegion mr) { verify_region(mr, dirty_card, true /* val_equals */); } #endif void CardTableModRefBS::print_on(outputStream* st) const { st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] byte_map_base: " INTPTR_FORMAT, p2i(_byte_map), p2i(_byte_map + _byte_map_size), p2i(byte_map_base)); } bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) { return CardTableModRefBS::card_will_be_scanned(cv) || _rs->is_prev_nonclean_card_val(cv); }; bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) { return cv != clean_card && (CardTableModRefBS::card_may_have_been_dirty(cv) || CardTableRS::youngergen_may_have_been_dirty(cv)); };