diff -r e0d59f0c2b7d -r 22ee476cc664 src/hotspot/share/memory/archiveUtils.hpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/hotspot/share/memory/archiveUtils.hpp Wed Nov 13 16:36:54 2019 -0800 @@ -0,0 +1,136 @@ +/* + * Copyright (c) 2019, 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. + * + */ + +#ifndef SHARE_MEMORY_ARCHIVEUTILS_HPP +#define SHARE_MEMORY_ARCHIVEUTILS_HPP + +#include "logging/log.hpp" +#include "runtime/arguments.hpp" +#include "utilities/bitMap.hpp" + +// ArchivePtrMarker is used to mark the location of pointers embedded in a CDS archive. E.g., when an +// InstanceKlass k is dumped, we mark the location of the k->_name pointer by effectively calling +// mark_pointer(/*ptr_loc=*/&k->_name). It's required that (_prt_base <= ptr_loc < _ptr_end). _ptr_base is +// fixed, but _ptr_end can be expanded as more objects are dumped. +class ArchivePtrMarker : AllStatic { + static CHeapBitMap* _ptrmap; + static address* _ptr_base; + static address* _ptr_end; + + // Once _ptrmap is compacted, we don't allow bit marking anymore. This is to + // avoid unintentional copy operations after the bitmap has been finalized and written. + static bool _compacted; +public: + static void initialize(CHeapBitMap* ptrmap, address* ptr_base, address* ptr_end); + static void mark_pointer(address* ptr_loc); + static void compact(address relocatable_base, address relocatable_end); + static void compact(size_t max_non_null_offset); + + template + static void mark_pointer(T* ptr_loc) { + mark_pointer((address*)ptr_loc); + } + + static void expand_ptr_end(address *new_ptr_end) { + assert(_ptr_end <= new_ptr_end, "must be"); + _ptr_end = new_ptr_end; + } + + static CHeapBitMap* ptrmap() { + return _ptrmap; + } +}; + +// SharedDataRelocator is used to shift pointers in the CDS archive. +// +// The CDS archive is basically a contiguous block of memory (divided into several regions) +// that contains multiple objects. The objects may contain direct pointers that point to other objects +// within the archive (e.g., InstanceKlass::_name points to a Symbol in the archive). During dumping, we +// built a bitmap that marks the locations of all these pointers (using ArchivePtrMarker, see comments above). +// +// The contents of the archive assumes that it’s mapped at the default SharedBaseAddress (e.g. 0x800000000). +// If the archive ends up being mapped at a different address (e.g. 0x810000000), SharedDataRelocator +// is used to shift each marked pointer by a delta (0x10000000 in this example), so that it points to +// the actually mapped location of the target object. +template +class SharedDataRelocator: public BitMapClosure { + // for all (address** p), where (is_marked(p) && _patch_base <= p && p < _patch_end) { *p += delta; } + + // Patch all pointers within this region that are marked. + address* _patch_base; + address* _patch_end; + + // Before patching, all pointers must point to this region. + address _valid_old_base; + address _valid_old_end; + + // After patching, all pointers must point to this region. + address _valid_new_base; + address _valid_new_end; + + // How much to relocate for each pointer. + intx _delta; + + // The following fields are used only when COMPACTING == true; + // The highest offset (inclusive) in the bitmap that contains a non-null pointer. + // This is used at dump time to reduce the size of the bitmap (which may have been over-allocated). + size_t _max_non_null_offset; + CHeapBitMap* _ptrmap; + + public: + SharedDataRelocator(address* patch_base, address* patch_end, + address valid_old_base, address valid_old_end, + address valid_new_base, address valid_new_end, intx delta, + CHeapBitMap* ptrmap = NULL) : + _patch_base(patch_base), _patch_end(patch_end), + _valid_old_base(valid_old_base), _valid_old_end(valid_old_end), + _valid_new_base(valid_new_base), _valid_new_end(valid_new_end), + _delta(delta) { + log_debug(cds, reloc)("SharedDataRelocator::_patch_base = " PTR_FORMAT, p2i(_patch_base)); + log_debug(cds, reloc)("SharedDataRelocator::_patch_end = " PTR_FORMAT, p2i(_patch_end)); + log_debug(cds, reloc)("SharedDataRelocator::_valid_old_base = " PTR_FORMAT, p2i(_valid_old_base)); + log_debug(cds, reloc)("SharedDataRelocator::_valid_old_end = " PTR_FORMAT, p2i(_valid_old_end)); + log_debug(cds, reloc)("SharedDataRelocator::_valid_new_base = " PTR_FORMAT, p2i(_valid_new_base)); + log_debug(cds, reloc)("SharedDataRelocator::_valid_new_end = " PTR_FORMAT, p2i(_valid_new_end)); + if (COMPACTING) { + assert(ptrmap != NULL, "must be"); + _max_non_null_offset = 0; + _ptrmap = ptrmap; + } else { + // Don't touch the _max_non_null_offset and _ptrmap fields. Hopefully a good C++ compiler can + // elide them. + assert(ptrmap == NULL, "must be"); + } + } + + size_t max_non_null_offset() { + assert(COMPACTING, "must be"); + return _max_non_null_offset; + } + + inline bool do_bit(size_t offset); +}; + + +#endif // SHARE_MEMORY_ARCHIVEUTILS_HPP