2 * Copyright (c) 1998 Doug Rabson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
28 #ifndef _MACHINE_ATOMIC_H_
29 #define _MACHINE_ATOMIC_H_
32 #error this file needs sys/cdefs.h as a prerequisite
35 #define mb() __asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
36 #define wmb() __asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
37 #define rmb() __asm __volatile("lock; addl $0,(%%esp)" : : : "memory")
40 * Various simple operations on memory, each of which is atomic in the
41 * presence of interrupts and multiple processors.
43 * atomic_set_char(P, V) (*(u_char *)(P) |= (V))
44 * atomic_clear_char(P, V) (*(u_char *)(P) &= ~(V))
45 * atomic_add_char(P, V) (*(u_char *)(P) += (V))
46 * atomic_subtract_char(P, V) (*(u_char *)(P) -= (V))
48 * atomic_set_short(P, V) (*(u_short *)(P) |= (V))
49 * atomic_clear_short(P, V) (*(u_short *)(P) &= ~(V))
50 * atomic_add_short(P, V) (*(u_short *)(P) += (V))
51 * atomic_subtract_short(P, V) (*(u_short *)(P) -= (V))
53 * atomic_set_int(P, V) (*(u_int *)(P) |= (V))
54 * atomic_clear_int(P, V) (*(u_int *)(P) &= ~(V))
55 * atomic_add_int(P, V) (*(u_int *)(P) += (V))
56 * atomic_subtract_int(P, V) (*(u_int *)(P) -= (V))
57 * atomic_readandclear_int(P) (return (*(u_int *)(P)); *(u_int *)(P) = 0;)
59 * atomic_set_long(P, V) (*(u_long *)(P) |= (V))
60 * atomic_clear_long(P, V) (*(u_long *)(P) &= ~(V))
61 * atomic_add_long(P, V) (*(u_long *)(P) += (V))
62 * atomic_subtract_long(P, V) (*(u_long *)(P) -= (V))
63 * atomic_readandclear_long(P) (return (*(u_long *)(P)); *(u_long *)(P) = 0;)
67 * The above functions are expanded inline in the statically-linked
68 * kernel. Lock prefixes are generated if an SMP kernel is being
71 * Kernel modules call real functions which are built into the kernel.
72 * This allows kernel modules to be portable between UP and SMP systems.
74 #if defined(KLD_MODULE) || !defined(__GNUCLIKE_ASM)
75 #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V) \
76 void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v); \
77 void atomic_##NAME##_barr_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
79 int atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src);
80 u_int atomic_fetchadd_int(volatile u_int *p, u_int v);
82 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP) \
83 u_##TYPE atomic_load_acq_##TYPE(volatile u_##TYPE *p); \
84 void atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
86 #else /* !KLD_MODULE && __GNUCLIKE_ASM */
89 * For userland, always use lock prefixes so that the binaries will run
90 * on both SMP and !SMP systems.
92 #if defined(SMP) || !defined(_KERNEL)
93 #define MPLOCKED "lock ; "
99 * The assembly is volatilized to avoid code chunk removal by the compiler.
100 * GCC aggressively reorders operations and memory clobbering is necessary
101 * in order to avoid that for memory barriers.
103 #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V) \
104 static __inline void \
105 atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
107 __asm __volatile(MPLOCKED OP \
109 : CONS (V), "m" (*p)); \
112 static __inline void \
113 atomic_##NAME##_barr_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
115 __asm __volatile(MPLOCKED OP \
117 : CONS (V), "m" (*p) \
123 * Atomic compare and set, used by the mutex functions
125 * if (*dst == exp) *dst = src (all 32 bit words)
127 * Returns 0 on failure, non-zero on success
130 #ifdef CPU_DISABLE_CMPXCHG
133 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
146 "# atomic_cmpset_int"
147 : "=q" (res), /* 0 */
157 #else /* !CPU_DISABLE_CMPXCHG */
160 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
169 "# atomic_cmpset_int"
170 : "=a" (res), /* 0 */
180 #endif /* CPU_DISABLE_CMPXCHG */
183 * Atomically add the value of v to the integer pointed to by p and return
184 * the previous value of *p.
186 static __inline u_int
187 atomic_fetchadd_int(volatile u_int *p, u_int v)
193 "# atomic_fetchadd_int"
194 : "+r" (v), /* 0 (result) */
201 #if defined(_KERNEL) && !defined(SMP)
204 * We assume that a = b will do atomic loads and stores. However, on a
205 * PentiumPro or higher, reads may pass writes, so for that case we have
206 * to use a serializing instruction (i.e. with LOCK) to do the load in
207 * SMP kernels. For UP kernels, however, the cache of the single processor
208 * is always consistent, so we only need to take care of compiler.
210 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP) \
211 static __inline u_##TYPE \
212 atomic_load_acq_##TYPE(volatile u_##TYPE *p) \
217 __asm __volatile("" : : : "memory"); \
221 static __inline void \
222 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
224 __asm __volatile("" : : : "memory"); \
229 #else /* !(_KERNEL && !SMP) */
231 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP) \
232 static __inline u_##TYPE \
233 atomic_load_acq_##TYPE(volatile u_##TYPE *p) \
237 __asm __volatile(MPLOCKED LOP \
238 : "=a" (res), /* 0 */ \
247 * The XCHG instruction asserts LOCK automagically. \
249 static __inline void \
250 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
252 __asm __volatile(SOP \
253 : "=m" (*p), /* 0 */ \
260 #endif /* _KERNEL && !SMP */
262 #endif /* KLD_MODULE || !__GNUCLIKE_ASM */
264 ATOMIC_ASM(set, char, "orb %b1,%0", "iq", v);
265 ATOMIC_ASM(clear, char, "andb %b1,%0", "iq", ~v);
266 ATOMIC_ASM(add, char, "addb %b1,%0", "iq", v);
267 ATOMIC_ASM(subtract, char, "subb %b1,%0", "iq", v);
269 ATOMIC_ASM(set, short, "orw %w1,%0", "ir", v);
270 ATOMIC_ASM(clear, short, "andw %w1,%0", "ir", ~v);
271 ATOMIC_ASM(add, short, "addw %w1,%0", "ir", v);
272 ATOMIC_ASM(subtract, short, "subw %w1,%0", "ir", v);
274 ATOMIC_ASM(set, int, "orl %1,%0", "ir", v);
275 ATOMIC_ASM(clear, int, "andl %1,%0", "ir", ~v);
276 ATOMIC_ASM(add, int, "addl %1,%0", "ir", v);
277 ATOMIC_ASM(subtract, int, "subl %1,%0", "ir", v);
279 ATOMIC_ASM(set, long, "orl %1,%0", "ir", v);
280 ATOMIC_ASM(clear, long, "andl %1,%0", "ir", ~v);
281 ATOMIC_ASM(add, long, "addl %1,%0", "ir", v);
282 ATOMIC_ASM(subtract, long, "subl %1,%0", "ir", v);
284 ATOMIC_STORE_LOAD(char, "cmpxchgb %b0,%1", "xchgb %b1,%0");
285 ATOMIC_STORE_LOAD(short,"cmpxchgw %w0,%1", "xchgw %w1,%0");
286 ATOMIC_STORE_LOAD(int, "cmpxchgl %0,%1", "xchgl %1,%0");
287 ATOMIC_STORE_LOAD(long, "cmpxchgl %0,%1", "xchgl %1,%0");
290 #undef ATOMIC_STORE_LOAD
292 #ifndef WANT_FUNCTIONS
295 atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src)
298 return (atomic_cmpset_int((volatile u_int *)dst, (u_int)exp,
302 static __inline u_long
303 atomic_fetchadd_long(volatile u_long *p, u_long v)
306 return (atomic_fetchadd_int((volatile u_int *)p, (u_int)v));
309 /* Read the current value and store a zero in the destination. */
310 #ifdef __GNUCLIKE_ASM
312 static __inline u_int
313 atomic_readandclear_int(volatile u_int *addr)
320 "# atomic_readandclear_int"
321 : "+r" (res), /* 0 */
328 static __inline u_long
329 atomic_readandclear_long(volatile u_long *addr)
336 "# atomic_readandclear_long"
337 : "+r" (res), /* 0 */
344 #else /* !__GNUCLIKE_ASM */
346 u_int atomic_readandclear_int(volatile u_int *addr);
347 u_long atomic_readandclear_long(volatile u_long *addr);
349 #endif /* __GNUCLIKE_ASM */
351 #define atomic_set_acq_char atomic_set_barr_char
352 #define atomic_set_rel_char atomic_set_barr_char
353 #define atomic_clear_acq_char atomic_clear_barr_char
354 #define atomic_clear_rel_char atomic_clear_barr_char
355 #define atomic_add_acq_char atomic_add_barr_char
356 #define atomic_add_rel_char atomic_add_barr_char
357 #define atomic_subtract_acq_char atomic_subtract_barr_char
358 #define atomic_subtract_rel_char atomic_subtract_barr_char
360 #define atomic_set_acq_short atomic_set_barr_short
361 #define atomic_set_rel_short atomic_set_barr_short
362 #define atomic_clear_acq_short atomic_clear_barr_short
363 #define atomic_clear_rel_short atomic_clear_barr_short
364 #define atomic_add_acq_short atomic_add_barr_short
365 #define atomic_add_rel_short atomic_add_barr_short
366 #define atomic_subtract_acq_short atomic_subtract_barr_short
367 #define atomic_subtract_rel_short atomic_subtract_barr_short
369 #define atomic_set_acq_int atomic_set_barr_int
370 #define atomic_set_rel_int atomic_set_barr_int
371 #define atomic_clear_acq_int atomic_clear_barr_int
372 #define atomic_clear_rel_int atomic_clear_barr_int
373 #define atomic_add_acq_int atomic_add_barr_int
374 #define atomic_add_rel_int atomic_add_barr_int
375 #define atomic_subtract_acq_int atomic_subtract_barr_int
376 #define atomic_subtract_rel_int atomic_subtract_barr_int
377 #define atomic_cmpset_acq_int atomic_cmpset_int
378 #define atomic_cmpset_rel_int atomic_cmpset_int
380 #define atomic_set_acq_long atomic_set_barr_long
381 #define atomic_set_rel_long atomic_set_barr_long
382 #define atomic_clear_acq_long atomic_clear_barr_long
383 #define atomic_clear_rel_long atomic_clear_barr_long
384 #define atomic_add_acq_long atomic_add_barr_long
385 #define atomic_add_rel_long atomic_add_barr_long
386 #define atomic_subtract_acq_long atomic_subtract_barr_long
387 #define atomic_subtract_rel_long atomic_subtract_barr_long
388 #define atomic_cmpset_acq_long atomic_cmpset_long
389 #define atomic_cmpset_rel_long atomic_cmpset_long
391 /* Operations on 8-bit bytes. */
392 #define atomic_set_8 atomic_set_char
393 #define atomic_set_acq_8 atomic_set_acq_char
394 #define atomic_set_rel_8 atomic_set_rel_char
395 #define atomic_clear_8 atomic_clear_char
396 #define atomic_clear_acq_8 atomic_clear_acq_char
397 #define atomic_clear_rel_8 atomic_clear_rel_char
398 #define atomic_add_8 atomic_add_char
399 #define atomic_add_acq_8 atomic_add_acq_char
400 #define atomic_add_rel_8 atomic_add_rel_char
401 #define atomic_subtract_8 atomic_subtract_char
402 #define atomic_subtract_acq_8 atomic_subtract_acq_char
403 #define atomic_subtract_rel_8 atomic_subtract_rel_char
404 #define atomic_load_acq_8 atomic_load_acq_char
405 #define atomic_store_rel_8 atomic_store_rel_char
407 /* Operations on 16-bit words. */
408 #define atomic_set_16 atomic_set_short
409 #define atomic_set_acq_16 atomic_set_acq_short
410 #define atomic_set_rel_16 atomic_set_rel_short
411 #define atomic_clear_16 atomic_clear_short
412 #define atomic_clear_acq_16 atomic_clear_acq_short
413 #define atomic_clear_rel_16 atomic_clear_rel_short
414 #define atomic_add_16 atomic_add_short
415 #define atomic_add_acq_16 atomic_add_acq_short
416 #define atomic_add_rel_16 atomic_add_rel_short
417 #define atomic_subtract_16 atomic_subtract_short
418 #define atomic_subtract_acq_16 atomic_subtract_acq_short
419 #define atomic_subtract_rel_16 atomic_subtract_rel_short
420 #define atomic_load_acq_16 atomic_load_acq_short
421 #define atomic_store_rel_16 atomic_store_rel_short
423 /* Operations on 32-bit double words. */
424 #define atomic_set_32 atomic_set_int
425 #define atomic_set_acq_32 atomic_set_acq_int
426 #define atomic_set_rel_32 atomic_set_rel_int
427 #define atomic_clear_32 atomic_clear_int
428 #define atomic_clear_acq_32 atomic_clear_acq_int
429 #define atomic_clear_rel_32 atomic_clear_rel_int
430 #define atomic_add_32 atomic_add_int
431 #define atomic_add_acq_32 atomic_add_acq_int
432 #define atomic_add_rel_32 atomic_add_rel_int
433 #define atomic_subtract_32 atomic_subtract_int
434 #define atomic_subtract_acq_32 atomic_subtract_acq_int
435 #define atomic_subtract_rel_32 atomic_subtract_rel_int
436 #define atomic_load_acq_32 atomic_load_acq_int
437 #define atomic_store_rel_32 atomic_store_rel_int
438 #define atomic_cmpset_32 atomic_cmpset_int
439 #define atomic_cmpset_acq_32 atomic_cmpset_acq_int
440 #define atomic_cmpset_rel_32 atomic_cmpset_rel_int
441 #define atomic_readandclear_32 atomic_readandclear_int
442 #define atomic_fetchadd_32 atomic_fetchadd_int
444 /* Operations on pointers. */
445 #define atomic_set_ptr(p, v) \
446 atomic_set_int((volatile u_int *)(p), (u_int)(v))
447 #define atomic_set_acq_ptr(p, v) \
448 atomic_set_acq_int((volatile u_int *)(p), (u_int)(v))
449 #define atomic_set_rel_ptr(p, v) \
450 atomic_set_rel_int((volatile u_int *)(p), (u_int)(v))
451 #define atomic_clear_ptr(p, v) \
452 atomic_clear_int((volatile u_int *)(p), (u_int)(v))
453 #define atomic_clear_acq_ptr(p, v) \
454 atomic_clear_acq_int((volatile u_int *)(p), (u_int)(v))
455 #define atomic_clear_rel_ptr(p, v) \
456 atomic_clear_rel_int((volatile u_int *)(p), (u_int)(v))
457 #define atomic_add_ptr(p, v) \
458 atomic_add_int((volatile u_int *)(p), (u_int)(v))
459 #define atomic_add_acq_ptr(p, v) \
460 atomic_add_acq_int((volatile u_int *)(p), (u_int)(v))
461 #define atomic_add_rel_ptr(p, v) \
462 atomic_add_rel_int((volatile u_int *)(p), (u_int)(v))
463 #define atomic_subtract_ptr(p, v) \
464 atomic_subtract_int((volatile u_int *)(p), (u_int)(v))
465 #define atomic_subtract_acq_ptr(p, v) \
466 atomic_subtract_acq_int((volatile u_int *)(p), (u_int)(v))
467 #define atomic_subtract_rel_ptr(p, v) \
468 atomic_subtract_rel_int((volatile u_int *)(p), (u_int)(v))
469 #define atomic_load_acq_ptr(p) \
470 atomic_load_acq_int((volatile u_int *)(p))
471 #define atomic_store_rel_ptr(p, v) \
472 atomic_store_rel_int((volatile u_int *)(p), (v))
473 #define atomic_cmpset_ptr(dst, old, new) \
474 atomic_cmpset_int((volatile u_int *)(dst), (u_int)(old), (u_int)(new))
475 #define atomic_cmpset_acq_ptr(dst, old, new) \
476 atomic_cmpset_acq_int((volatile u_int *)(dst), (u_int)(old), \
478 #define atomic_cmpset_rel_ptr(dst, old, new) \
479 atomic_cmpset_rel_int((volatile u_int *)(dst), (u_int)(old), \
481 #define atomic_readandclear_ptr(p) \
482 atomic_readandclear_int((volatile u_int *)(p))
484 #endif /* !WANT_FUNCTIONS */
486 #endif /* !_MACHINE_ATOMIC_H_ */