1 /* 2 * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2020 SAP SE. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "precompiled.hpp" 27 28 #include "memory/metaspace/commitMask.hpp" 29 #include "memory/metaspace/metaspaceCommon.hpp" 30 #include "memory/metaspace/settings.hpp" 31 #include "runtime/stubRoutines.hpp" 32 33 #include "utilities/align.hpp" 34 #include "utilities/debug.hpp" 35 36 namespace metaspace { 37 38 CommitMask::CommitMask(const MetaWord* start, size_t word_size) 39 : CHeapBitMap(mask_size(word_size, Settings::commit_granule_words())) 40 , _base(start) 41 , _word_size(word_size) 42 , _words_per_bit(Settings::commit_granule_words()) 43 { 44 assert(_word_size > 0 && _words_per_bit > 0 && 45 is_aligned(_word_size, _words_per_bit), "Sanity"); 46 } 47 48 #ifdef ASSERT 49 50 // This is very expensive 51 static const bool TEST_UNCOMMITTED_REGION = false; 52 53 volatile u1 x; 54 55 static void check_range_is_accessible(const MetaWord* p, size_t word_size) { 56 const MetaWord* const p_end = p + word_size; 57 u1 x2 = 0; 58 for (const MetaWord* q = p; q < p_end; q += os::vm_page_size() / BytesPerWord) { 59 x2 += *(u1*)q; 60 } 61 x = x2; 62 } 63 64 void CommitMask::verify(bool slow) const { 65 66 // Walk the whole commit mask. 67 // For each 1 bit, check if the associated granule is accessible. 68 // For each 0 bit, check if the associated granule is not accessible. Slow mode only. 69 70 assert(_base != NULL && _word_size > 0 && _words_per_bit > 0, "Sanity"); 71 assert_is_aligned(_base, _words_per_bit * BytesPerWord); 72 assert_is_aligned(_word_size, _words_per_bit); 73 74 if (slow) { 75 for (idx_t i = 0; i < size(); i ++) { 76 const MetaWord* const p = _base + (i * _words_per_bit); 77 if (at(i)) { 78 // Should be accessible. Just touch it. 79 check_range_is_accessible(p, _words_per_bit); 80 } else { 81 // Note: results may differ between platforms. On Linux, this should be true since 82 // we uncommit memory by setting protection to PROT_NONE. We may have to look if 83 // this works as expected on other platforms. 84 if (TEST_UNCOMMITTED_REGION && CanUseSafeFetch32()) { 85 assert(os::is_readable_pointer(p) == false, 86 "index %u, pointer " PTR_FORMAT ", should not be accessible.", 87 (unsigned)i, p2i(p)); 88 } 89 } 90 } 91 } 92 93 } 94 95 #endif // ASSERT 96 97 void CommitMask::print_on(outputStream* st) const { 98 99 st->print("commit mask, base " PTR_FORMAT ":", p2i(base())); 100 101 for (idx_t i = 0; i < size(); i ++) { 102 st->print("%c", at(i) ? 'X' : '-'); 103 } 104 105 st->cr(); 106 107 } 108 109 } // namespace metaspace 110