The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/i386/include/atomic.h

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    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: releng/5.0/sys/i386/include/atomic.h 105117 2002-10-14 19:33:12Z pirzyk $
   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, CONS, 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 #ifdef __GNUC__
   79 
   80 /*
   81  * For userland, assume the SMP case and use lock prefixes so that
   82  * the binaries will run on both types of systems.
   83  */
   84 #if defined(SMP) || !defined(_KERNEL)
   85 #define MPLOCKED        lock ;
   86 #else
   87 #define MPLOCKED
   88 #endif
   89 
   90 /*
   91  * The assembly is volatilized to demark potential before-and-after side
   92  * effects if an interrupt or SMP collision were to occur.
   93  */
   94 #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V)             \
   95 static __inline void                                    \
   96 atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
   97 {                                                       \
   98         __asm __volatile(__XSTRING(MPLOCKED) OP         \
   99                          : "+m" (*p)                    \
  100                          : CONS (V));                   \
  101 }
  102 
  103 #else /* !__GNUC__ */
  104 
  105 #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V)                             \
  106 extern void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
  107 
  108 #endif /* __GNUC__ */
  109 
  110 /*
  111  * Atomic compare and set, used by the mutex functions
  112  *
  113  * if (*dst == exp) *dst = src (all 32 bit words)
  114  *
  115  * Returns 0 on failure, non-zero on success
  116  */
  117 
  118 #if defined(__GNUC__)
  119 
  120 #if defined(I386_CPU) || defined(CPU_DISABLE_CMPXCHG)
  121 
  122 static __inline int
  123 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
  124 {
  125         int res = exp;
  126 
  127         __asm __volatile(
  128         "       pushfl ;                "
  129         "       cli ;                   "
  130         "       cmpl    %0,%2 ;         "
  131         "       jne     1f ;            "
  132         "       movl    %1,%2 ;         "
  133         "1:                             "
  134         "       sete    %%al;           "
  135         "       movzbl  %%al,%0 ;       "
  136         "       popfl ;                 "
  137         "# atomic_cmpset_int"
  138         : "+a" (res)                    /* 0 (result) */
  139         : "r" (src),                    /* 1 */
  140           "m" (*(dst))                  /* 2 */
  141         : "memory");
  142 
  143         return (res);
  144 }
  145 
  146 #else /* defined(I386_CPU) */
  147 
  148 static __inline int
  149 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
  150 {
  151         int res = exp;
  152 
  153         __asm __volatile (
  154         "       " __XSTRING(MPLOCKED) " "
  155         "       cmpxchgl %1,%2 ;        "
  156         "       setz    %%al ;          "
  157         "       movzbl  %%al,%0 ;       "
  158         "1:                             "
  159         "# atomic_cmpset_int"
  160         : "+a" (res)                    /* 0 (result) */
  161         : "r" (src),                    /* 1 */
  162           "m" (*(dst))                  /* 2 */
  163         : "memory");                             
  164 
  165         return (res);
  166 }
  167 
  168 #endif /* defined(I386_CPU) */
  169 
  170 #endif /* defined(__GNUC__) */
  171 
  172 #if defined(__GNUC__)
  173 
  174 #if defined(I386_CPU)
  175 
  176 /*
  177  * We assume that a = b will do atomic loads and stores.
  178  *
  179  * XXX: This is _NOT_ safe on a P6 or higher because it does not guarantee
  180  * memory ordering.  These should only be used on a 386.
  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         return (*p);                                    \
  187 }                                                       \
  188                                                         \
  189 static __inline void                                    \
  190 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  191 {                                                       \
  192         *p = v;                                         \
  193         __asm __volatile("" : : : "memory");            \
  194 }
  195 
  196 #else /* !defined(I386_CPU) */
  197 
  198 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)               \
  199 static __inline u_##TYPE                                \
  200 atomic_load_acq_##TYPE(volatile u_##TYPE *p)            \
  201 {                                                       \
  202         u_##TYPE res;                                   \
  203                                                         \
  204         __asm __volatile(__XSTRING(MPLOCKED) LOP        \
  205         : "=a" (res),                   /* 0 (result) */\
  206           "+m" (*p)                     /* 1 */         \
  207         : : "memory");                                  \
  208                                                         \
  209         return (res);                                   \
  210 }                                                       \
  211                                                         \
  212 /*                                                      \
  213  * The XCHG instruction asserts LOCK automagically.     \
  214  */                                                     \
  215 static __inline void                                    \
  216 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  217 {                                                       \
  218         __asm __volatile(SOP                            \
  219         : "+m" (*p),                    /* 0 */         \
  220           "+r" (v)                      /* 1 */         \
  221         : : "memory");                                  \
  222 }
  223 
  224 #endif  /* defined(I386_CPU) */
  225 
  226 #else /* !defined(__GNUC__) */
  227 
  228 extern int atomic_cmpset_int(volatile u_int *, u_int, u_int);
  229 
  230 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)                               \
  231 extern u_##TYPE atomic_load_acq_##TYPE(volatile u_##TYPE *p);           \
  232 extern void atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
  233 
  234 #endif /* defined(__GNUC__) */
  235 
  236 #endif /* KLD_MODULE */
  237 
  238 ATOMIC_ASM(set,      char,  "orb %b1,%0",  "iq",  v);
  239 ATOMIC_ASM(clear,    char,  "andb %b1,%0", "iq", ~v);
  240 ATOMIC_ASM(add,      char,  "addb %b1,%0", "iq",  v);
  241 ATOMIC_ASM(subtract, char,  "subb %b1,%0", "iq",  v);
  242 
  243 ATOMIC_ASM(set,      short, "orw %w1,%0",  "ir",  v);
  244 ATOMIC_ASM(clear,    short, "andw %w1,%0", "ir", ~v);
  245 ATOMIC_ASM(add,      short, "addw %w1,%0", "ir",  v);
  246 ATOMIC_ASM(subtract, short, "subw %w1,%0", "ir",  v);
  247 
  248 ATOMIC_ASM(set,      int,   "orl %1,%0",   "ir",  v);
  249 ATOMIC_ASM(clear,    int,   "andl %1,%0",  "ir", ~v);
  250 ATOMIC_ASM(add,      int,   "addl %1,%0",  "ir",  v);
  251 ATOMIC_ASM(subtract, int,   "subl %1,%0",  "ir",  v);
  252 
  253 ATOMIC_ASM(set,      long,  "orl %1,%0",   "ir",  v);
  254 ATOMIC_ASM(clear,    long,  "andl %1,%0",  "ir", ~v);
  255 ATOMIC_ASM(add,      long,  "addl %1,%0",  "ir",  v);
  256 ATOMIC_ASM(subtract, long,  "subl %1,%0",  "ir",  v);
  257 
  258 ATOMIC_STORE_LOAD(char, "cmpxchgb %b0,%1", "xchgb %b1,%0");
  259 ATOMIC_STORE_LOAD(short,"cmpxchgw %w0,%1", "xchgw %w1,%0");
  260 ATOMIC_STORE_LOAD(int,  "cmpxchgl %0,%1",  "xchgl %1,%0");
  261 ATOMIC_STORE_LOAD(long, "cmpxchgl %0,%1",  "xchgl %1,%0");
  262 
  263 #undef ATOMIC_ASM
  264 #undef ATOMIC_STORE_LOAD
  265 
  266 #define atomic_set_acq_char             atomic_set_char
  267 #define atomic_set_rel_char             atomic_set_char
  268 #define atomic_clear_acq_char           atomic_clear_char
  269 #define atomic_clear_rel_char           atomic_clear_char
  270 #define atomic_add_acq_char             atomic_add_char
  271 #define atomic_add_rel_char             atomic_add_char
  272 #define atomic_subtract_acq_char        atomic_subtract_char
  273 #define atomic_subtract_rel_char        atomic_subtract_char
  274 
  275 #define atomic_set_acq_short            atomic_set_short
  276 #define atomic_set_rel_short            atomic_set_short
  277 #define atomic_clear_acq_short          atomic_clear_short
  278 #define atomic_clear_rel_short          atomic_clear_short
  279 #define atomic_add_acq_short            atomic_add_short
  280 #define atomic_add_rel_short            atomic_add_short
  281 #define atomic_subtract_acq_short       atomic_subtract_short
  282 #define atomic_subtract_rel_short       atomic_subtract_short
  283 
  284 #define atomic_set_acq_int              atomic_set_int
  285 #define atomic_set_rel_int              atomic_set_int
  286 #define atomic_clear_acq_int            atomic_clear_int
  287 #define atomic_clear_rel_int            atomic_clear_int
  288 #define atomic_add_acq_int              atomic_add_int
  289 #define atomic_add_rel_int              atomic_add_int
  290 #define atomic_subtract_acq_int         atomic_subtract_int
  291 #define atomic_subtract_rel_int         atomic_subtract_int
  292 #define atomic_cmpset_acq_int           atomic_cmpset_int
  293 #define atomic_cmpset_rel_int           atomic_cmpset_int
  294 
  295 #define atomic_set_acq_long             atomic_set_long
  296 #define atomic_set_rel_long             atomic_set_long
  297 #define atomic_clear_acq_long           atomic_clear_long
  298 #define atomic_clear_rel_long           atomic_clear_long
  299 #define atomic_add_acq_long             atomic_add_long
  300 #define atomic_add_rel_long             atomic_add_long
  301 #define atomic_subtract_acq_long        atomic_subtract_long
  302 #define atomic_subtract_rel_long        atomic_subtract_long
  303 #define atomic_cmpset_long              atomic_cmpset_int
  304 #define atomic_cmpset_acq_long          atomic_cmpset_acq_int
  305 #define atomic_cmpset_rel_long          atomic_cmpset_rel_int
  306 
  307 #define atomic_cmpset_acq_ptr           atomic_cmpset_ptr
  308 #define atomic_cmpset_rel_ptr           atomic_cmpset_ptr
  309 
  310 #define atomic_set_8            atomic_set_char
  311 #define atomic_set_acq_8        atomic_set_acq_char
  312 #define atomic_set_rel_8        atomic_set_rel_char
  313 #define atomic_clear_8          atomic_clear_char
  314 #define atomic_clear_acq_8      atomic_clear_acq_char
  315 #define atomic_clear_rel_8      atomic_clear_rel_char
  316 #define atomic_add_8            atomic_add_char
  317 #define atomic_add_acq_8        atomic_add_acq_char
  318 #define atomic_add_rel_8        atomic_add_rel_char
  319 #define atomic_subtract_8       atomic_subtract_char
  320 #define atomic_subtract_acq_8   atomic_subtract_acq_char
  321 #define atomic_subtract_rel_8   atomic_subtract_rel_char
  322 #define atomic_load_acq_8       atomic_load_acq_char
  323 #define atomic_store_rel_8      atomic_store_rel_char
  324 
  325 #define atomic_set_16           atomic_set_short
  326 #define atomic_set_acq_16       atomic_set_acq_short
  327 #define atomic_set_rel_16       atomic_set_rel_short
  328 #define atomic_clear_16         atomic_clear_short
  329 #define atomic_clear_acq_16     atomic_clear_acq_short
  330 #define atomic_clear_rel_16     atomic_clear_rel_short
  331 #define atomic_add_16           atomic_add_short
  332 #define atomic_add_acq_16       atomic_add_acq_short
  333 #define atomic_add_rel_16       atomic_add_rel_short
  334 #define atomic_subtract_16      atomic_subtract_short
  335 #define atomic_subtract_acq_16  atomic_subtract_acq_short
  336 #define atomic_subtract_rel_16  atomic_subtract_rel_short
  337 #define atomic_load_acq_16      atomic_load_acq_short
  338 #define atomic_store_rel_16     atomic_store_rel_short
  339 
  340 #define atomic_set_32           atomic_set_int
  341 #define atomic_set_acq_32       atomic_set_acq_int
  342 #define atomic_set_rel_32       atomic_set_rel_int
  343 #define atomic_clear_32         atomic_clear_int
  344 #define atomic_clear_acq_32     atomic_clear_acq_int
  345 #define atomic_clear_rel_32     atomic_clear_rel_int
  346 #define atomic_add_32           atomic_add_int
  347 #define atomic_add_acq_32       atomic_add_acq_int
  348 #define atomic_add_rel_32       atomic_add_rel_int
  349 #define atomic_subtract_32      atomic_subtract_int
  350 #define atomic_subtract_acq_32  atomic_subtract_acq_int
  351 #define atomic_subtract_rel_32  atomic_subtract_rel_int
  352 #define atomic_load_acq_32      atomic_load_acq_int
  353 #define atomic_store_rel_32     atomic_store_rel_int
  354 #define atomic_cmpset_32        atomic_cmpset_int
  355 #define atomic_cmpset_acq_32    atomic_cmpset_acq_int
  356 #define atomic_cmpset_rel_32    atomic_cmpset_rel_int
  357 #define atomic_readandclear_32  atomic_readandclear_int
  358 
  359 #if !defined(WANT_FUNCTIONS)
  360 static __inline int
  361 atomic_cmpset_ptr(volatile void *dst, void *exp, void *src)
  362 {
  363 
  364         return (atomic_cmpset_int((volatile u_int *)dst, (u_int)exp,
  365             (u_int)src));
  366 }
  367 
  368 static __inline void *
  369 atomic_load_acq_ptr(volatile void *p)
  370 {
  371         return (void *)atomic_load_acq_int((volatile u_int *)p);
  372 }
  373 
  374 static __inline void
  375 atomic_store_rel_ptr(volatile void *p, void *v)
  376 {
  377         atomic_store_rel_int((volatile u_int *)p, (u_int)v);
  378 }
  379 
  380 #define ATOMIC_PTR(NAME)                                \
  381 static __inline void                                    \
  382 atomic_##NAME##_ptr(volatile void *p, uintptr_t v)      \
  383 {                                                       \
  384         atomic_##NAME##_int((volatile u_int *)p, v);    \
  385 }                                                       \
  386                                                         \
  387 static __inline void                                    \
  388 atomic_##NAME##_acq_ptr(volatile void *p, uintptr_t v)  \
  389 {                                                       \
  390         atomic_##NAME##_acq_int((volatile u_int *)p, v);\
  391 }                                                       \
  392                                                         \
  393 static __inline void                                    \
  394 atomic_##NAME##_rel_ptr(volatile void *p, uintptr_t v)  \
  395 {                                                       \
  396         atomic_##NAME##_rel_int((volatile u_int *)p, v);\
  397 }
  398 
  399 ATOMIC_PTR(set)
  400 ATOMIC_PTR(clear)
  401 ATOMIC_PTR(add)
  402 ATOMIC_PTR(subtract)
  403 
  404 #undef ATOMIC_PTR
  405 
  406 #if defined(__GNUC__)
  407 
  408 static __inline u_int
  409 atomic_readandclear_int(volatile u_int *addr)
  410 {
  411         u_int result;
  412 
  413         __asm __volatile (
  414         "       xorl    %0,%0 ;         "
  415         "       xchgl   %1,%0 ;         "
  416         "# atomic_readandclear_int"
  417         : "=&r" (result)                /* 0 (result) */
  418         : "m" (*addr));                 /* 1 (addr) */
  419 
  420         return (result);
  421 }
  422 
  423 static __inline u_long
  424 atomic_readandclear_long(volatile u_long *addr)
  425 {
  426         u_long result;
  427 
  428         __asm __volatile (
  429         "       xorl    %0,%0 ;         "
  430         "       xchgl   %1,%0 ;         "
  431         "# atomic_readandclear_int"
  432         : "=&r" (result)                /* 0 (result) */
  433         : "m" (*addr));                 /* 1 (addr) */
  434 
  435         return (result);
  436 }
  437 
  438 #else /* !defined(__GNUC__) */
  439 
  440 extern u_long   atomic_readandclear_long(volatile u_long *);
  441 extern u_int    atomic_readandclear_int(volatile u_int *);
  442 
  443 #endif /* defined(__GNUC__) */
  444 
  445 #endif  /* !defined(WANT_FUNCTIONS) */
  446 #endif /* ! _MACHINE_ATOMIC_H_ */

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