1 /*
2 * Copyright (c) 2023, 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
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7 * published by the Free Software Foundation.
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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 *
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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24
25 #ifndef SHARE_CDS_ARCHIVEHEAPWRITER_HPP
26 #define SHARE_CDS_ARCHIVEHEAPWRITER_HPP
27
28 #include "cds/heapShared.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/allStatic.hpp"
31 #include "oops/oopHandle.hpp"
32 #include "utilities/bitMap.hpp"
33 #include "utilities/exceptions.hpp"
34 #include "utilities/growableArray.hpp"
35 #include "utilities/macros.hpp"
36 #include "utilities/resourceHash.hpp"
37
38 class MemRegion;
39
40 class ArchiveHeapInfo {
41 MemRegion _buffer_region; // Contains the archived objects to be written into the CDS archive.
42 CHeapBitMap _oopmap;
43 CHeapBitMap _ptrmap;
44 size_t _heap_roots_offset; // Offset of the HeapShared::roots() object, from the bottom
45 // of the archived heap objects, in bytes.
46
47 public:
48 ArchiveHeapInfo() : _buffer_region(), _oopmap(128, mtClassShared), _ptrmap(128, mtClassShared) {}
49 bool is_used() { return !_buffer_region.is_empty(); }
50
51 MemRegion buffer_region() { return _buffer_region; }
52 void set_buffer_region(MemRegion r) { _buffer_region = r; }
53
54 char* buffer_start() { return (char*)_buffer_region.start(); }
55 size_t buffer_byte_size() { return _buffer_region.byte_size(); }
56
57 CHeapBitMap* oopmap() { return &_oopmap; }
58 CHeapBitMap* ptrmap() { return &_ptrmap; }
59
60 void set_heap_roots_offset(size_t n) { _heap_roots_offset = n; }
61 size_t heap_roots_offset() const { return _heap_roots_offset; }
62 };
63
64 #if INCLUDE_CDS_JAVA_HEAP
65 class ArchiveHeapWriter : AllStatic {
66 // ArchiveHeapWriter manipulates three types of addresses:
67 //
68 // "source" vs "buffered" vs "requested"
69 //
70 // (Note: the design and convention is the same as for the archiving of Metaspace objects.
71 // See archiveBuilder.hpp.)
72 //
73 // - "source objects" are regular Java objects allocated during the execution
74 // of "java -Xshare:dump". They can be used as regular oops.
75 //
76 // HeapShared::archive_objects() recursively searches for the oops that need to be
77 // stored into the CDS archive. These are entered into HeapShared::archived_object_cache().
78 //
79 // - "buffered objects" are copies of the "source objects", and are stored in into
80 // ArchiveHeapWriter::_buffer, which is a GrowableArray that sits outside of
81 // the valid heap range. Therefore we avoid using the addresses of these copies
82 // as oops. They are usually called "buffered_addr" in the code (of the type "address").
83 //
84 // The buffered objects are stored contiguously, possibly with interleaving fillers
85 // to make sure no objects span across boundaries of MIN_GC_REGION_ALIGNMENT.
86 //
87 // - Each archived object has a "requested address" -- at run time, if the object
88 // can be mapped at this address, we can avoid relocation.
89 //
90 // The requested address is implemented differently depending on UseCompressedOops:
91 //
92 // UseCompressedOops == true:
93 // The archived objects are stored assuming that the runtime COOPS compression
94 // scheme is exactly the same as in dump time (or else a more expensive runtime relocation
95 // would be needed.)
96 //
97 // At dump time, we assume that the runtime heap range is exactly the same as
98 // in dump time. The requested addresses of the archived objects are chosen such that
99 // they would occupy the top end of a G1 heap (TBD when dumping is supported by other
100 // collectors. See JDK-8298614).
101 //
102 // UseCompressedOops == false:
103 // At runtime, the heap range is usually picked (randomly) by the OS, so we will almost always
104 // need to perform relocation. Hence, the goal of the "requested address" is to ensure that
105 // the contents of the archived objects are deterministic. I.e., the oop fields of archived
106 // objects will always point to deterministic addresses.
107 //
108 // For G1, the archived heap is written such that the lowest archived object is placed
109 // at NOCOOPS_REQUESTED_BASE. (TBD after JDK-8298614).
110 // ----------------------------------------------------------------------
111
112 public:
113 static const intptr_t NOCOOPS_REQUESTED_BASE = 0x10000000;
114
115 private:
116 class EmbeddedOopRelocator;
117 struct NativePointerInfo {
118 oop _src_obj;
119 int _field_offset;
120 };
121
122 // The minimum region size of all collectors that are supported by CDS in
123 // ArchiveHeapLoader::can_map() mode. Currently only G1 is supported. G1's region size
124 // depends on -Xmx, but can never be smaller than 1 * M.
125 // (TODO: Perhaps change to 256K to be compatible with Shenandoah)
126 static constexpr int MIN_GC_REGION_ALIGNMENT = 1 * M;
127
128 static GrowableArrayCHeap<u1, mtClassShared>* _buffer;
129
130 // The number of bytes that have written into _buffer (may be smaller than _buffer->length()).
131 static size_t _buffer_used;
132
133 // The bottom of the copy of Heap::roots() inside this->_buffer.
134 static size_t _heap_roots_offset;
135 static size_t _heap_roots_word_size;
136
137 // The address range of the requested location of the archived heap objects.
138 static address _requested_bottom;
139 static address _requested_top;
140
141 static GrowableArrayCHeap<NativePointerInfo, mtClassShared>* _native_pointers;
142 static GrowableArrayCHeap<oop, mtClassShared>* _source_objs;
143
144 typedef ResourceHashtable<size_t, oop,
145 36137, // prime number
146 AnyObj::C_HEAP,
147 mtClassShared> BufferOffsetToSourceObjectTable;
148 static BufferOffsetToSourceObjectTable* _buffer_offset_to_source_obj_table;
149
150 static void allocate_buffer();
151 static void ensure_buffer_space(size_t min_bytes);
152
153 // Both Java bytearray and GrowableArraty use int indices and lengths. Do a safe typecast with range check
154 static int to_array_index(size_t i) {
155 assert(i <= (size_t)max_jint, "must be");
156 return (int)i;
157 }
158 static int to_array_length(size_t n) {
159 return to_array_index(n);
160 }
161
162 template <typename T> static T offset_to_buffered_address(size_t offset) {
163 return (T)(_buffer->adr_at(to_array_index(offset)));
164 }
165
166 static address buffer_bottom() {
167 return offset_to_buffered_address<address>(0);
168 }
169
170 // The exclusive end of the last object that was copied into the buffer.
171 static address buffer_top() {
172 return buffer_bottom() + _buffer_used;
173 }
174
175 static bool in_buffer(address buffered_addr) {
176 return (buffer_bottom() <= buffered_addr) && (buffered_addr < buffer_top());
177 }
178
179 static size_t buffered_address_to_offset(address buffered_addr) {
180 assert(in_buffer(buffered_addr), "sanity");
181 return buffered_addr - buffer_bottom();
182 }
183
184 static void copy_roots_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots);
185 static void copy_source_objs_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots);
186 static size_t copy_one_source_obj_to_buffer(oop src_obj);
187
188 static void maybe_fill_gc_region_gap(size_t required_byte_size);
189 static size_t filler_array_byte_size(int length);
190 static int filler_array_length(size_t fill_bytes);
191 static HeapWord* init_filler_array_at_buffer_top(int array_length, size_t fill_bytes);
192
193 static void set_requested_address(ArchiveHeapInfo* info);
194 static void relocate_embedded_oops(GrowableArrayCHeap<oop, mtClassShared>* roots, ArchiveHeapInfo* info);
195 static void compute_ptrmap(ArchiveHeapInfo *info);
196 static bool is_in_requested_range(oop o);
197 static oop requested_obj_from_buffer_offset(size_t offset);
198
199 static oop load_oop_from_buffer(oop* buffered_addr);
200 static oop load_oop_from_buffer(narrowOop* buffered_addr);
201 inline static void store_oop_in_buffer(oop* buffered_addr, oop requested_obj);
202 inline static void store_oop_in_buffer(narrowOop* buffered_addr, oop requested_obj);
203
204 template <typename T> static oop load_source_oop_from_buffer(T* buffered_addr);
205 template <typename T> static void store_requested_oop_in_buffer(T* buffered_addr, oop request_oop);
206
207 template <typename T> static T* requested_addr_to_buffered_addr(T* p);
208 template <typename T> static void relocate_field_in_buffer(T* field_addr_in_buffer, CHeapBitMap* oopmap);
209 template <typename T> static void mark_oop_pointer(T* buffered_addr, CHeapBitMap* oopmap);
210 template <typename T> static void relocate_root_at(oop requested_roots, int index, CHeapBitMap* oopmap);
211
212 static void update_header_for_requested_obj(oop requested_obj, oop src_obj, Klass* src_klass);
213 public:
214 static void init() NOT_CDS_JAVA_HEAP_RETURN;
215 static void add_source_obj(oop src_obj);
216 static bool is_too_large_to_archive(size_t size);
217 static bool is_too_large_to_archive(oop obj);
218 static bool is_string_too_large_to_archive(oop string);
219 static void write(GrowableArrayCHeap<oop, mtClassShared>*, ArchiveHeapInfo* heap_info);
220 static address requested_address(); // requested address of the lowest achived heap object
221 static oop heap_roots_requested_address(); // requested address of HeapShared::roots()
222 static address buffered_heap_roots_addr() {
223 return offset_to_buffered_address<address>(_heap_roots_offset);
224 }
225 static size_t heap_roots_word_size() {
226 return _heap_roots_word_size;
227 }
228 static size_t get_filler_size_at(address buffered_addr);
229
230 static void mark_native_pointer(oop src_obj, int offset);
231 static bool is_marked_as_native_pointer(ArchiveHeapInfo* heap_info, oop src_obj, int field_offset);
232 static oop source_obj_to_requested_obj(oop src_obj);
233 static oop buffered_addr_to_source_obj(address buffered_addr);
234 static address buffered_addr_to_requested_addr(address buffered_addr);
235
236 // Archived heap object headers carry pre-computed narrow Klass ids calculated with the
237 // following scheme:
238 // 1) the encoding base must be the mapping start address.
239 // 2) shift must be large enough to result in an encoding range that covers the runtime Klass range.
240 // That Klass range is defined by CDS archive size and runtime class space size. Luckily, the maximum
241 // size can be predicted: archive size is assumed to be <1G, class space size capped at 3G, and at
242 // runtime we put both regions adjacent to each other. Therefore, runtime Klass range size < 4G.
243 // Since nKlass itself is 32 bit, our encoding range len is 4G, and since we set the base directly
244 // at mapping start, these 4G are enough. Therefore, we don't need to shift at all (shift=0).
245 static constexpr int precomputed_narrow_klass_shift = 0;
246
247 };
248 #endif // INCLUDE_CDS_JAVA_HEAP
249 #endif // SHARE_CDS_ARCHIVEHEAPWRITER_HPP