xref: /freebsd/sys/i386/include/atomic.h (revision d9009094)
1 /*-
2  * Copyright (c) 1998 Doug Rabson
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $FreeBSD$
27  */
28 #ifndef _MACHINE_ATOMIC_H_
29 #define _MACHINE_ATOMIC_H_
30 
31 /*
32  * Various simple arithmetic on memory which is atomic in the presence
33  * of interrupts and multiple processors.
34  *
35  * atomic_set_char(P, V)	(*(u_char*)(P) |= (V))
36  * atomic_clear_char(P, V)	(*(u_char*)(P) &= ~(V))
37  * atomic_add_char(P, V)	(*(u_char*)(P) += (V))
38  * atomic_subtract_char(P, V)	(*(u_char*)(P) -= (V))
39  *
40  * atomic_set_short(P, V)	(*(u_short*)(P) |= (V))
41  * atomic_clear_short(P, V)	(*(u_short*)(P) &= ~(V))
42  * atomic_add_short(P, V)	(*(u_short*)(P) += (V))
43  * atomic_subtract_short(P, V)	(*(u_short*)(P) -= (V))
44  *
45  * atomic_set_int(P, V)		(*(u_int*)(P) |= (V))
46  * atomic_clear_int(P, V)	(*(u_int*)(P) &= ~(V))
47  * atomic_add_int(P, V)		(*(u_int*)(P) += (V))
48  * atomic_subtract_int(P, V)	(*(u_int*)(P) -= (V))
49  * atomic_readandclear_int(P)	(return  *(u_int*)P; *(u_int*)P = 0;)
50  *
51  * atomic_set_long(P, V)	(*(u_long*)(P) |= (V))
52  * atomic_clear_long(P, V)	(*(u_long*)(P) &= ~(V))
53  * atomic_add_long(P, V)	(*(u_long*)(P) += (V))
54  * atomic_subtract_long(P, V)	(*(u_long*)(P) -= (V))
55  * atomic_readandclear_long(P)	(return  *(u_long*)P; *(u_long*)P = 0;)
56  */
57 
58 /*
59  * The above functions are expanded inline in the statically-linked
60  * kernel.  Lock prefixes are generated if an SMP kernel is being
61  * built.
62  *
63  * Kernel modules call real functions which are built into the kernel.
64  * This allows kernel modules to be portable between UP and SMP systems.
65  */
66 #if defined(KLD_MODULE)
67 #define ATOMIC_ASM(NAME, TYPE, OP, V)			\
68 void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v);
69 
70 int atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src);
71 
72 #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)			\
73 u_##TYPE	atomic_load_acq_##TYPE(volatile u_##TYPE *p);	\
74 void		atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v);
75 
76 #else /* !KLD_MODULE */
77 
78 /*
79  * For userland, assume the SMP case and use lock prefixes so that
80  * the binaries will run on both types of systems.
81  */
82 #if defined(SMP) || !defined(_KERNEL)
83 #if defined(LOCORE)
84 #define	MPLOCKED	lock ;
85 #else /* !LOCORE */
86 #define MPLOCKED	"lock ; "
87 #endif /* LOCORE */
88 #else /* SMP || !_KERNEL */
89 #define MPLOCKED
90 #endif /* SMP || !_KERNEL */
91 
92 #if !defined(LOCORE)
93 /*
94  * The assembly is volatilized to demark potential before-and-after side
95  * effects if an interrupt or SMP collision were to occur.
96  */
97 #define ATOMIC_ASM(NAME, TYPE, OP, V)			\
98 static __inline void					\
99 atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
100 {							\
101 	__asm __volatile(MPLOCKED OP			\
102 			 : "+m" (*p)			\
103 			 : "ir" (V));			\
104 }
105 
106 /*
107  * Atomic compare and set, used by the mutex functions
108  *
109  * if (*dst == exp) *dst = src (all 32 bit words)
110  *
111  * Returns 0 on failure, non-zero on success
112  */
113 
114 #if defined(I386_CPU)
115 static __inline int
116 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
117 {
118 	int res = exp;
119 
120 	__asm __volatile(
121 	"	pushfl ;		"
122 	"	cli ;			"
123 	"	cmpl	%0,%2 ;		"
124 	"	jne	1f ;		"
125 	"	movl	%1,%2 ;		"
126 	"1:				"
127 	"       sete	%%al;		"
128 	"	movzbl	%%al,%0 ;	"
129 	"	popfl ;			"
130 	"# atomic_cmpset_int"
131 	: "+a" (res)			/* 0 (result) */
132 	: "r" (src),			/* 1 */
133 	  "m" (*(dst))			/* 2 */
134 	: "memory");
135 
136 	return (res);
137 }
138 #else /* defined(I386_CPU) */
139 static __inline int
140 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
141 {
142 	int res = exp;
143 
144 	__asm __volatile (
145 	"	" MPLOCKED "		"
146 	"	cmpxchgl %1,%2 ;	"
147 	"       setz	%%al ;		"
148 	"	movzbl	%%al,%0 ;	"
149 	"1:				"
150 	"# atomic_cmpset_int"
151 	: "+a" (res)			/* 0 (result) */
152 	: "r" (src),			/* 1 */
153 	  "m" (*(dst))			/* 2 */
154 	: "memory");
155 
156 	return (res);
157 }
158 #endif /* defined(I386_CPU) */
159 
160 #if defined(I386_CPU)
161 /*
162  * We assume that a = b will do atomic loads and stores.
163  *
164  * XXX: This is _NOT_ safe on a P6 or higher because it does not guarantee
165  * memory ordering.  These should only be used on a 386.
166  */
167 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)		\
168 static __inline u_##TYPE				\
169 atomic_load_acq_##TYPE(volatile u_##TYPE *p)		\
170 {							\
171 	return (*p);					\
172 }							\
173 							\
174 static __inline void					\
175 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
176 {							\
177 	*p = v;						\
178 	__asm __volatile("" : : : "memory");		\
179 }
180 #else
181 
182 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)		\
183 static __inline u_##TYPE				\
184 atomic_load_acq_##TYPE(volatile u_##TYPE *p)		\
185 {							\
186 	u_##TYPE res;					\
187 							\
188 	__asm __volatile(MPLOCKED LOP			\
189 	: "=a" (res),			/* 0 (result) */\
190 	  "+m" (*p)			/* 1 */		\
191 	: : "cc", "memory");			 	\
192 							\
193 	return (res);					\
194 }							\
195 							\
196 /*							\
197  * The XCHG instruction asserts LOCK automagically.	\
198  */							\
199 static __inline void					\
200 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
201 {							\
202 	__asm __volatile(SOP				\
203 	: "+m" (*p),			/* 0 */		\
204 	  "+r" (v)			/* 1 */		\
205 	: : "memory");				 	\
206 }
207 #endif	/* defined(I386_CPU) */
208 #endif	/* !defined(LOCORE) */
209 #endif /* KLD_MODULE */
210 
211 #if !defined(LOCORE)
212 ATOMIC_ASM(set,	     char,  "orb %b1,%0",   v)
213 ATOMIC_ASM(clear,    char,  "andb %b1,%0", ~v)
214 ATOMIC_ASM(add,	     char,  "addb %b1,%0",  v)
215 ATOMIC_ASM(subtract, char,  "subb %b1,%0",  v)
216 
217 ATOMIC_ASM(set,	     short, "orw %w1,%0",   v)
218 ATOMIC_ASM(clear,    short, "andw %w1,%0", ~v)
219 ATOMIC_ASM(add,	     short, "addw %w1,%0",  v)
220 ATOMIC_ASM(subtract, short, "subw %w1,%0",  v)
221 
222 ATOMIC_ASM(set,	     int,   "orl %1,%0",   v)
223 ATOMIC_ASM(clear,    int,   "andl %1,%0", ~v)
224 ATOMIC_ASM(add,	     int,   "addl %1,%0",  v)
225 ATOMIC_ASM(subtract, int,   "subl %1,%0",  v)
226 
227 ATOMIC_ASM(set,	     long,  "orl %1,%0",   v)
228 ATOMIC_ASM(clear,    long,  "andl %1,%0", ~v)
229 ATOMIC_ASM(add,	     long,  "addl %1,%0",  v)
230 ATOMIC_ASM(subtract, long,  "subl %1,%0",  v)
231 
232 ATOMIC_STORE_LOAD(char,	"cmpxchgb %b0,%1", "xchgb %b1,%0")
233 ATOMIC_STORE_LOAD(short,"cmpxchgw %w0,%1", "xchgw %w1,%0")
234 ATOMIC_STORE_LOAD(int,	"cmpxchgl %0,%1",  "xchgl %1,%0")
235 ATOMIC_STORE_LOAD(long,	"cmpxchgl %0,%1",  "xchgl %1,%0")
236 
237 #undef ATOMIC_ASM
238 #undef ATOMIC_STORE_LOAD
239 
240 #define	atomic_set_acq_char		atomic_set_char
241 #define	atomic_set_rel_char		atomic_set_char
242 #define	atomic_clear_acq_char		atomic_clear_char
243 #define	atomic_clear_rel_char		atomic_clear_char
244 #define	atomic_add_acq_char		atomic_add_char
245 #define	atomic_add_rel_char		atomic_add_char
246 #define	atomic_subtract_acq_char	atomic_subtract_char
247 #define	atomic_subtract_rel_char	atomic_subtract_char
248 
249 #define	atomic_set_acq_short		atomic_set_short
250 #define	atomic_set_rel_short		atomic_set_short
251 #define	atomic_clear_acq_short		atomic_clear_short
252 #define	atomic_clear_rel_short		atomic_clear_short
253 #define	atomic_add_acq_short		atomic_add_short
254 #define	atomic_add_rel_short		atomic_add_short
255 #define	atomic_subtract_acq_short	atomic_subtract_short
256 #define	atomic_subtract_rel_short	atomic_subtract_short
257 
258 #define	atomic_set_acq_int		atomic_set_int
259 #define	atomic_set_rel_int		atomic_set_int
260 #define	atomic_clear_acq_int		atomic_clear_int
261 #define	atomic_clear_rel_int		atomic_clear_int
262 #define	atomic_add_acq_int		atomic_add_int
263 #define	atomic_add_rel_int		atomic_add_int
264 #define	atomic_subtract_acq_int		atomic_subtract_int
265 #define	atomic_subtract_rel_int		atomic_subtract_int
266 #define atomic_cmpset_acq_int		atomic_cmpset_int
267 #define atomic_cmpset_rel_int		atomic_cmpset_int
268 
269 #define	atomic_set_acq_long		atomic_set_long
270 #define	atomic_set_rel_long		atomic_set_long
271 #define	atomic_clear_acq_long		atomic_clear_long
272 #define	atomic_clear_rel_long		atomic_clear_long
273 #define	atomic_add_acq_long		atomic_add_long
274 #define	atomic_add_rel_long		atomic_add_long
275 #define	atomic_subtract_acq_long	atomic_subtract_long
276 #define	atomic_subtract_rel_long	atomic_subtract_long
277 #define	atomic_cmpset_long		atomic_cmpset_int
278 #define	atomic_cmpset_acq_long		atomic_cmpset_acq_int
279 #define	atomic_cmpset_rel_long		atomic_cmpset_rel_int
280 
281 #define atomic_cmpset_acq_ptr		atomic_cmpset_ptr
282 #define atomic_cmpset_rel_ptr		atomic_cmpset_ptr
283 
284 #define	atomic_set_8		atomic_set_char
285 #define	atomic_set_acq_8	atomic_set_acq_char
286 #define	atomic_set_rel_8	atomic_set_rel_char
287 #define	atomic_clear_8		atomic_clear_char
288 #define	atomic_clear_acq_8	atomic_clear_acq_char
289 #define	atomic_clear_rel_8	atomic_clear_rel_char
290 #define	atomic_add_8		atomic_add_char
291 #define	atomic_add_acq_8	atomic_add_acq_char
292 #define	atomic_add_rel_8	atomic_add_rel_char
293 #define	atomic_subtract_8	atomic_subtract_char
294 #define	atomic_subtract_acq_8	atomic_subtract_acq_char
295 #define	atomic_subtract_rel_8	atomic_subtract_rel_char
296 #define	atomic_load_acq_8	atomic_load_acq_char
297 #define	atomic_store_rel_8	atomic_store_rel_char
298 
299 #define	atomic_set_16		atomic_set_short
300 #define	atomic_set_acq_16	atomic_set_acq_short
301 #define	atomic_set_rel_16	atomic_set_rel_short
302 #define	atomic_clear_16		atomic_clear_short
303 #define	atomic_clear_acq_16	atomic_clear_acq_short
304 #define	atomic_clear_rel_16	atomic_clear_rel_short
305 #define	atomic_add_16		atomic_add_short
306 #define	atomic_add_acq_16	atomic_add_acq_short
307 #define	atomic_add_rel_16	atomic_add_rel_short
308 #define	atomic_subtract_16	atomic_subtract_short
309 #define	atomic_subtract_acq_16	atomic_subtract_acq_short
310 #define	atomic_subtract_rel_16	atomic_subtract_rel_short
311 #define	atomic_load_acq_16	atomic_load_acq_short
312 #define	atomic_store_rel_16	atomic_store_rel_short
313 
314 #define	atomic_set_32		atomic_set_int
315 #define	atomic_set_acq_32	atomic_set_acq_int
316 #define	atomic_set_rel_32	atomic_set_rel_int
317 #define	atomic_clear_32		atomic_clear_int
318 #define	atomic_clear_acq_32	atomic_clear_acq_int
319 #define	atomic_clear_rel_32	atomic_clear_rel_int
320 #define	atomic_add_32		atomic_add_int
321 #define	atomic_add_acq_32	atomic_add_acq_int
322 #define	atomic_add_rel_32	atomic_add_rel_int
323 #define	atomic_subtract_32	atomic_subtract_int
324 #define	atomic_subtract_acq_32	atomic_subtract_acq_int
325 #define	atomic_subtract_rel_32	atomic_subtract_rel_int
326 #define	atomic_load_acq_32	atomic_load_acq_int
327 #define	atomic_store_rel_32	atomic_store_rel_int
328 #define	atomic_cmpset_32	atomic_cmpset_int
329 #define	atomic_cmpset_acq_32	atomic_cmpset_acq_int
330 #define	atomic_cmpset_rel_32	atomic_cmpset_rel_int
331 #define	atomic_readandclear_32	atomic_readandclear_int
332 
333 #if !defined(WANT_FUNCTIONS)
334 static __inline int
335 atomic_cmpset_ptr(volatile void *dst, void *exp, void *src)
336 {
337 
338 	return (atomic_cmpset_int((volatile u_int *)dst, (u_int)exp,
339 	    (u_int)src));
340 }
341 
342 static __inline void *
343 atomic_load_acq_ptr(volatile void *p)
344 {
345 	return (void *)atomic_load_acq_int((volatile u_int *)p);
346 }
347 
348 static __inline void
349 atomic_store_rel_ptr(volatile void *p, void *v)
350 {
351 	atomic_store_rel_int((volatile u_int *)p, (u_int)v);
352 }
353 
354 #define ATOMIC_PTR(NAME)				\
355 static __inline void					\
356 atomic_##NAME##_ptr(volatile void *p, uintptr_t v)	\
357 {							\
358 	atomic_##NAME##_int((volatile u_int *)p, v);	\
359 }							\
360 							\
361 static __inline void					\
362 atomic_##NAME##_acq_ptr(volatile void *p, uintptr_t v)	\
363 {							\
364 	atomic_##NAME##_acq_int((volatile u_int *)p, v);\
365 }							\
366 							\
367 static __inline void					\
368 atomic_##NAME##_rel_ptr(volatile void *p, uintptr_t v)	\
369 {							\
370 	atomic_##NAME##_rel_int((volatile u_int *)p, v);\
371 }
372 
373 ATOMIC_PTR(set)
374 ATOMIC_PTR(clear)
375 ATOMIC_PTR(add)
376 ATOMIC_PTR(subtract)
377 
378 #undef ATOMIC_PTR
379 
380 static __inline u_int
381 atomic_readandclear_int(volatile u_int *addr)
382 {
383 	u_int result;
384 
385 	__asm __volatile (
386 	"	xorl	%0,%0 ;		"
387 	"	xchgl	%1,%0 ;		"
388 	"# atomic_readandclear_int"
389 	: "=&r" (result)		/* 0 (result) */
390 	: "m" (*addr));			/* 1 (addr) */
391 
392 	return (result);
393 }
394 
395 static __inline u_long
396 atomic_readandclear_long(volatile u_long *addr)
397 {
398 	u_long result;
399 
400 	__asm __volatile (
401 	"	xorl	%0,%0 ;		"
402 	"	xchgl	%1,%0 ;		"
403 	"# atomic_readandclear_int"
404 	: "=&r" (result)		/* 0 (result) */
405 	: "m" (*addr));			/* 1 (addr) */
406 
407 	return (result);
408 }
409 #endif	/* !defined(WANT_FUNCTIONS) */
410 #endif	/* !defined(LOCORE) */
411 #endif /* ! _MACHINE_ATOMIC_H_ */
412