atomic.h revision 88617 
1/*-
2 * Copyright (c) 1998 Doug Rabson.
3 * Copyright (c) 2001 Jake Burkholder.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 *	from: FreeBSD: src/sys/i386/include/atomic.h,v 1.20 2001/02/11
28 * $FreeBSD: head/sys/sparc64/include/atomic.h 88617 2001-12-29 06:48:43Z jake $
29 */
30
31#ifndef	_MACHINE_ATOMIC_H_
32#define	_MACHINE_ATOMIC_H_
33
34#include <machine/cpufunc.h>
35
36/* Userland needs different ASI's. */
37#ifdef _KERNEL
38#define	__ASI_ATOMIC	ASI_N
39#else
40#define	__ASI_ATOMIC	ASI_P
41#endif
42
43/*
44 * Various simple arithmetic on memory which is atomic in the presence
45 * of interrupts and multiple processors.  See atomic(9) for details.
46 * Note that efficient hardware support exists only for the 32 and 64
47 * bit variants; the 8 and 16 bit versions are not provided and should
48 * not be used in MI code.
49 *
50 * This implementation takes advantage of the fact that the sparc64
51 * cas instruction is both a load and a store.  The loop is often coded
52 * as follows:
53 *
54 *	do {
55 *		expect = *p;
56 *		new = expect + 1;
57 *	} while (cas(p, expect, new) != expect);
58 *
59 * which performs an unnnecessary load on each iteration that the cas
60 * operation fails.  Modified as follows:
61 *
62 *	expect = *p;
63 *	for (;;) {
64 *		new = expect + 1;
65 *		result = cas(p, expect, new);
66 *		if (result == expect)
67 *			break;
68 *		expect = result;
69 *	}
70 *
71 * the return value of cas is used to avoid the extra reload.  At the
72 * time of writing, with gcc version 2.95.3, the branch for the if
73 * statement is predicted incorrectly as not taken, rather than taken.
74 * It is expected that the branch prediction hints available in gcc 3.0,
75 * __builtin_expect, will allow better code to be generated.
76 *
77 * The memory barriers provided by the acq and rel variants are intended
78 * to be sufficient for use of relaxed memory ordering.  Due to the
79 * suggested assembly syntax of the membar operands containing a #
80 * character, they cannot be used in macros.  The cmask and mmask bits
81 * are hard coded in machine/cpufunc.h and used here through macros.
82 * Hopefully sun will choose not to change the bit numbers.
83 */
84
85#define	itype(sz)	u_int ## sz ## _t
86
87#define	atomic_cas_32(p, e, s)	casa(p, e, s, __ASI_ATOMIC)
88#define	atomic_cas_64(p, e, s)	casxa(p, e, s, __ASI_ATOMIC)
89
90#define	atomic_cas(p, e, s, sz)						\
91	atomic_cas_ ## sz(p, e, s)
92
93#define	atomic_cas_acq(p, e, s, sz) ({					\
94	itype(sz) v;							\
95	v = atomic_cas(p, e, s, sz);					\
96	membar(LoadLoad | LoadStore);					\
97	v;								\
98})
99
100#define	atomic_cas_rel(p, e, s, sz) ({					\
101	itype(sz) v;							\
102	membar(LoadStore | StoreStore);					\
103	v = atomic_cas(p, e, s, sz);					\
104	v;								\
105})
106
107#define	atomic_op(p, op, v, sz) do {					\
108	itype(sz) e, r, s;						\
109	for (e = *(volatile itype(sz) *)p;; e = r) {			\
110		s = e op v;						\
111		r = atomic_cas_ ## sz(p, e, s);				\
112		if (r == e)						\
113			break;						\
114	}								\
115} while (0)
116
117#define	atomic_op_acq(p, op, v, sz) do {				\
118	atomic_op(p, op, v, sz);					\
119	membar(LoadLoad | LoadStore);					\
120} while (0)
121
122#define	atomic_op_rel(p, op, v, sz) do {				\
123	membar(LoadStore | StoreStore);					\
124	atomic_op(p, op, v, sz);					\
125} while (0)
126
127#define	atomic_load(p, sz)						\
128	atomic_cas(p, 0, 0, sz)
129
130#define	atomic_load_acq(p, sz) ({					\
131	itype(sz) v;							\
132	v = atomic_load(p, sz);						\
133	membar(LoadLoad | LoadStore);					\
134	v;								\
135})
136
137#define	atomic_load_clear(p, sz) ({					\
138	itype(sz) e, r;							\
139	for (e = *(volatile itype(sz) *)p;; e = r) {			\
140		r = atomic_cas(p, e, 0, sz);				\
141		if (r == e)						\
142			break;						\
143	}								\
144	e;								\
145})
146
147#define	atomic_store(p, v, sz) do {					\
148	itype(sz) e, r;							\
149	for (e = *(volatile itype(sz) *)p;; e = r) {			\
150		r = atomic_cas(p, e, v, sz);				\
151		if (r == e)						\
152			break;						\
153	}								\
154} while (0)
155
156#define	atomic_store_rel(p, v, sz) do {					\
157	membar(LoadStore | StoreStore);					\
158	atomic_store(p, v, sz);						\
159} while (0)
160
161#define	ATOMIC_GEN(name, ptype, vtype, atype, sz)			\
162									\
163static __inline void							\
164atomic_add_ ## name(volatile ptype p, atype v)				\
165{									\
166	atomic_op(p, +, v, sz);						\
167}									\
168static __inline void							\
169atomic_add_acq_ ## name(volatile ptype p, atype v)			\
170{									\
171	atomic_op_acq(p, +, v, sz);					\
172}									\
173static __inline void							\
174atomic_add_rel_ ## name(volatile ptype p, atype v)			\
175{									\
176	atomic_op_rel(p, +, v, sz);					\
177}									\
178									\
179static __inline void							\
180atomic_clear_ ## name(volatile ptype p, atype v)			\
181{									\
182	atomic_op(p, &, ~v, sz);					\
183}									\
184static __inline void							\
185atomic_clear_acq_ ## name(volatile ptype p, atype v)			\
186{									\
187	atomic_op_acq(p, &, ~v, sz);					\
188}									\
189static __inline void							\
190atomic_clear_rel_ ## name(volatile ptype p, atype v)			\
191{									\
192	atomic_op_rel(p, &, ~v, sz);					\
193}									\
194									\
195static __inline int							\
196atomic_cmpset_ ## name(volatile ptype p, vtype e, vtype s)		\
197{									\
198	return (((vtype)atomic_cas(p, e, s, sz)) == e);			\
199}									\
200static __inline int							\
201atomic_cmpset_acq_ ## name(volatile ptype p, vtype e, vtype s)		\
202{									\
203	return (((vtype)atomic_cas_acq(p, e, s, sz)) == e);		\
204}									\
205static __inline int							\
206atomic_cmpset_rel_ ## name(volatile ptype p, vtype e, vtype s)		\
207{									\
208	return (((vtype)atomic_cas_rel(p, e, s, sz)) == e);		\
209}									\
210									\
211static __inline vtype							\
212atomic_load_ ## name(volatile ptype p)					\
213{									\
214	return ((vtype)atomic_cas(p, 0, 0, sz));			\
215}									\
216static __inline vtype							\
217atomic_load_acq_ ## name(volatile ptype p)				\
218{									\
219	return ((vtype)atomic_cas_acq(p, 0, 0, sz));			\
220}									\
221									\
222static __inline vtype							\
223atomic_readandclear_ ## name(volatile ptype p)				\
224{									\
225	return ((vtype)atomic_load_clear(p, sz));			\
226}									\
227									\
228static __inline void							\
229atomic_set_ ## name(volatile ptype p, atype v)				\
230{									\
231	atomic_op(p, |, v, sz);						\
232}									\
233static __inline void							\
234atomic_set_acq_ ## name(volatile ptype p, atype v)			\
235{									\
236	atomic_op_acq(p, |, v, sz);					\
237}									\
238static __inline void							\
239atomic_set_rel_ ## name(volatile ptype p, atype v)			\
240{									\
241	atomic_op_rel(p, |, v, sz);					\
242}									\
243									\
244static __inline void							\
245atomic_subtract_ ## name(volatile ptype p, atype v)			\
246{									\
247	atomic_op(p, -, v, sz);						\
248}									\
249static __inline void							\
250atomic_subtract_acq_ ## name(volatile ptype p, atype v)			\
251{									\
252	atomic_op_acq(p, -, v, sz);					\
253}									\
254static __inline void							\
255atomic_subtract_rel_ ## name(volatile ptype p, atype v)			\
256{									\
257	atomic_op_rel(p, -, v, sz);					\
258}									\
259									\
260static __inline void							\
261atomic_store_ ## name(volatile ptype p, vtype v)			\
262{									\
263	atomic_store(p, v, sz);						\
264}									\
265static __inline void							\
266atomic_store_rel_ ## name(volatile ptype p, vtype v)			\
267{									\
268	atomic_store_rel(p, v, sz);					\
269}
270
271ATOMIC_GEN(int, int *, int, int, 32);
272ATOMIC_GEN(32, int *, int, int, 32);
273
274ATOMIC_GEN(long, long *, long, long, 64);
275ATOMIC_GEN(64, long *, long, long, 64);
276
277ATOMIC_GEN(ptr, void *, void *, uintptr_t, 64);
278
279#undef __ASI_ATOMIC
280#undef ATOMIC_GEN
281#undef atomic_cas_32
282#undef atomic_cas_64
283#undef atomic_cas
284#undef atomic_cas_acq
285#undef atomic_cas_rel
286#undef atomic_op
287#undef atomic_op_acq
288#undef atomic_op_rel
289#undef atomic_load_acq
290#undef atomic_store_rel
291#undef atomic_load_clear
292
293#endif /* !_MACHINE_ATOMIC_H_ */
294