1 /*
2 * Copyright (c) 2001, 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
25 #include "precompiled.hpp"
26 #include "runtime/atomic.hpp"
27 #ifdef TARGET_OS_FAMILY_linux
28 # include "os_linux.inline.hpp"
29 #endif
30 #ifdef TARGET_OS_FAMILY_solaris
31 # include "os_solaris.inline.hpp"
32 #endif
33 #ifdef TARGET_OS_FAMILY_windows
34 # include "os_windows.inline.hpp"
35 #endif
36 #ifdef TARGET_OS_FAMILY_aix
37 # include "os_aix.inline.hpp"
38 #endif
39 #ifdef TARGET_OS_FAMILY_bsd
40 # include "os_bsd.inline.hpp"
41 #endif
42
43 #include "runtime/atomic.inline.hpp"
44
45 jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
46 assert(sizeof(jbyte) == 1, "assumption.");
47 uintptr_t dest_addr = (uintptr_t)dest;
48 uintptr_t offset = dest_addr % sizeof(jint);
49 volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
50 jint cur = *dest_int;
51 jbyte* cur_as_bytes = (jbyte*)(&cur);
52 jint new_val = cur;
53 jbyte* new_val_as_bytes = (jbyte*)(&new_val);
54 new_val_as_bytes[offset] = exchange_value;
55 while (cur_as_bytes[offset] == compare_value) {
56 jint res = cmpxchg(new_val, dest_int, cur);
57 if (res == cur) break;
58 cur = res;
59 new_val = cur;
60 new_val_as_bytes[offset] = exchange_value;
61 }
62 return cur_as_bytes[offset];
63 }
64
65 unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {
66 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
67 return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);
68 }
69
70 unsigned Atomic::cmpxchg(unsigned int exchange_value,
71 volatile unsigned int* dest, unsigned int compare_value) {
72 assert(sizeof(unsigned int) == sizeof(jint), "more work to do");
73 return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,
74 (jint)compare_value);
75 }
76
77 julong Atomic::cmpxchg(julong exchange_value,
78 volatile julong* dest, julong compare_value) {
79 return (julong)Atomic::cmpxchg((jlong)exchange_value, (volatile jlong*)dest,
80 (jlong)compare_value);
81 }
82
83 julong Atomic::load(volatile julong* src) {
84 return (julong)load((volatile jlong*)src);
85 }
86
87 jlong Atomic::add(jlong add_value, volatile jlong* dest) {
88 jlong old = load(dest);
89 jlong new_value = old + add_value;
90 while (old != cmpxchg(new_value, dest, old)) {
91 old = load(dest);
92 new_value = old + add_value;
93 }
94 return old;
95 }
96
97 julong Atomic::add(julong add_value, volatile julong* dest) {
98 julong old = load(dest);
99 julong new_value = old + add_value;
100 while (old != cmpxchg(new_value, dest, old)) {
101 old = load(dest);
102 new_value = old + add_value;
103 }
104 return old;
105 }
106
107 void Atomic::inc(volatile short* dest) {
108 // Most platforms do not support atomic increment on a 2-byte value. However,
109 // if the value occupies the most significant 16 bits of an aligned 32-bit
110 // word, then we can do this with an atomic add of 0x10000 to the 32-bit word.
111 //
112 // The least significant parts of this 32-bit word will never be affected, even
113 // in case of overflow/underflow.
114 //
115 // Use the ATOMIC_SHORT_PAIR macro to get the desired alignment.
116 #ifdef VM_LITTLE_ENDIAN
117 assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
118 (void)Atomic::add(0x10000, (volatile int*)(dest-1));
119 #else
120 assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
121 (void)Atomic::add(0x10000, (volatile int*)(dest));
122 #endif
123 }
124
125 void Atomic::dec(volatile short* dest) {
126 #ifdef VM_LITTLE_ENDIAN
127 assert((intx(dest) & 0x03) == 0x02, "wrong alignment");
128 (void)Atomic::add(-0x10000, (volatile int*)(dest-1));
129 #else
130 assert((intx(dest) & 0x03) == 0x00, "wrong alignment");
131 (void)Atomic::add(-0x10000, (volatile int*)(dest));
132 #endif
133 }
134