1 /*
2 * Copyright (c) 2017, 2019, 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
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 #include "precompiled.hpp"
25 #include "gc/shared/gcLogPrecious.hpp"
26 #include "gc/z/zGlobals.hpp"
27 #include "runtime/globals.hpp"
28 #include "utilities/globalDefinitions.hpp"
29 #include "utilities/powerOfTwo.hpp"
30
31 #include <sys/mman.h>
32
33 //
34 // The heap can have three different layouts, depending on the max heap size.
35 //
36 // Address Space & Pointer Layout 1
37 // --------------------------------
38 //
39 // +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
40 // . .
41 // . .
42 // . .
43 // +--------------------------------+ 0x0000014000000000 (20TB)
44 // | Remapped View |
45 // +--------------------------------+ 0x0000010000000000 (16TB)
46 // . .
47 // +--------------------------------+ 0x00000c0000000000 (12TB)
48 // | Marked1 View |
49 // +--------------------------------+ 0x0000080000000000 (8TB)
50 // | Marked0 View |
51 // +--------------------------------+ 0x0000040000000000 (4TB)
52 // . .
53 // +--------------------------------+ 0x0000000000000000
54 //
55 // 6 4 4 4 4
56 // 3 6 5 2 1 0
57 // +--------------------+----+-----------------------------------------------+
58 // |00000000 00000000 00|1111|11 11111111 11111111 11111111 11111111 11111111|
59 // +--------------------+----+-----------------------------------------------+
60 // | | |
61 // | | * 41-0 Object Offset (42-bits, 4TB address space)
62 // | |
63 // | * 45-42 Metadata Bits (4-bits) 0001 = Marked0 (Address view 4-8TB)
64 // | 0010 = Marked1 (Address view 8-12TB)
65 // | 0100 = Remapped (Address view 16-20TB)
66 // | 1000 = Finalizable (Address view N/A)
67 // |
68 // * 63-46 Fixed (18-bits, always zero)
69 //
70 //
71 // Address Space & Pointer Layout 2
72 // --------------------------------
73 //
74 // +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
75 // . .
76 // . .
77 // . .
78 // +--------------------------------+ 0x0000280000000000 (40TB)
79 // | Remapped View |
80 // +--------------------------------+ 0x0000200000000000 (32TB)
81 // . .
82 // +--------------------------------+ 0x0000180000000000 (24TB)
83 // | Marked1 View |
84 // +--------------------------------+ 0x0000100000000000 (16TB)
85 // | Marked0 View |
86 // +--------------------------------+ 0x0000080000000000 (8TB)
87 // . .
88 // +--------------------------------+ 0x0000000000000000
89 //
90 // 6 4 4 4 4
91 // 3 7 6 3 2 0
92 // +------------------+-----+------------------------------------------------+
93 // |00000000 00000000 0|1111|111 11111111 11111111 11111111 11111111 11111111|
94 // +-------------------+----+------------------------------------------------+
95 // | | |
96 // | | * 42-0 Object Offset (43-bits, 8TB address space)
97 // | |
98 // | * 46-43 Metadata Bits (4-bits) 0001 = Marked0 (Address view 8-16TB)
99 // | 0010 = Marked1 (Address view 16-24TB)
100 // | 0100 = Remapped (Address view 32-40TB)
101 // | 1000 = Finalizable (Address view N/A)
102 // |
103 // * 63-47 Fixed (17-bits, always zero)
104 //
105 //
106 // Address Space & Pointer Layout 3
107 // --------------------------------
108 //
109 // +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
110 // . .
111 // . .
112 // . .
113 // +--------------------------------+ 0x0000500000000000 (80TB)
114 // | Remapped View |
115 // +--------------------------------+ 0x0000400000000000 (64TB)
116 // . .
117 // +--------------------------------+ 0x0000300000000000 (48TB)
118 // | Marked1 View |
119 // +--------------------------------+ 0x0000200000000000 (32TB)
120 // | Marked0 View |
121 // +--------------------------------+ 0x0000100000000000 (16TB)
122 // . .
123 // +--------------------------------+ 0x0000000000000000
124 //
125 // 6 4 4 4 4
126 // 3 8 7 4 3 0
127 // +------------------+----+-------------------------------------------------+
128 // |00000000 00000000 |1111|1111 11111111 11111111 11111111 11111111 11111111|
129 // +------------------+----+-------------------------------------------------+
130 // | | |
131 // | | * 43-0 Object Offset (44-bits, 16TB address space)
132 // | |
133 // | * 47-44 Metadata Bits (4-bits) 0001 = Marked0 (Address view 16-32TB)
134 // | 0010 = Marked1 (Address view 32-48TB)
135 // | 0100 = Remapped (Address view 64-80TB)
136 // | 1000 = Finalizable (Address view N/A)
137 // |
138 // * 63-48 Fixed (16-bits, always zero)
139 //
140
141 static size_t probe_valid_max_address_bit() {
142 const size_t page_size = (size_t) sysconf(_SC_PAGE_SIZE);
143 size_t max_address_bits = 0;
144 // TODO: Iterate from high to low addresses and stop at the first valid one, should be faster.
145 for (size_t i = 1; i <= sizeof(uintptr_t) * CHAR_BIT; ++i) {
146 const uintptr_t base_addr = ((uintptr_t) 1U) << i;
147 if (msync((void*)base_addr, page_size, MS_ASYNC) == 0) {
148 // msync suceeded, the address is valid, and maybe even already mapped.
149 max_address_bits = i;
150 continue;
151 }
152 if (errno != ENOMEM) {
153 // Some error occured. This should never happen, but msync
154 // has some undefined behavior, hence ignore this bit.
155 continue;
156 }
157 // Since msync failed with ENOMEM, the page might not be mapped.
158 // Try to map it, to see if the address is valid.
159 void* result_addr = mmap((void*) base_addr, page_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
160 if ((uintptr_t) result_addr == base_addr) {
161 // address is valid
162 max_address_bits = i;
163 }
164 if (result_addr != MAP_FAILED) {
165 munmap(result_addr, page_size);
166 }
167 }
168 max_address_bits += 1;
169 log_info_p(gc, init)("Probing address space for the number of valid bits: %zu", max_address_bits);
170 return max_address_bits;
171 }
172
173 size_t ZPlatformAddressOffsetBits() {
174 const static size_t ZAddressBits = probe_valid_max_address_bit();
175 const size_t max_address_offset_bits = ZAddressBits - 3;
176 const size_t min_address_offset_bits = max_address_offset_bits - 2;
177 const size_t address_offset = round_up_power_of_2(MaxHeapSize * ZVirtualToPhysicalRatio);
178 const size_t address_offset_bits = log2_intptr(address_offset);
179 return clamp(address_offset_bits, min_address_offset_bits, max_address_offset_bits);
180 }
181
182 size_t ZPlatformAddressMetadataShift() {
183 return ZPlatformAddressOffsetBits();
184 }