The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/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  * $FreeBSD$
   27  */
   28 #ifndef _MACHINE_ATOMIC_H_
   29 #define _MACHINE_ATOMIC_H_
   30 
   31 #ifndef _SYS_CDEFS_H_
   32 #error this file needs sys/cdefs.h as a prerequisite
   33 #endif
   34 
   35 /*
   36  * Various simple operations on memory, each of which is atomic in the
   37  * presence of interrupts and multiple processors.
   38  *
   39  * atomic_set_char(P, V)        (*(u_char *)(P) |= (V))
   40  * atomic_clear_char(P, V)      (*(u_char *)(P) &= ~(V))
   41  * atomic_add_char(P, V)        (*(u_char *)(P) += (V))
   42  * atomic_subtract_char(P, V)   (*(u_char *)(P) -= (V))
   43  *
   44  * atomic_set_short(P, V)       (*(u_short *)(P) |= (V))
   45  * atomic_clear_short(P, V)     (*(u_short *)(P) &= ~(V))
   46  * atomic_add_short(P, V)       (*(u_short *)(P) += (V))
   47  * atomic_subtract_short(P, V)  (*(u_short *)(P) -= (V))
   48  *
   49  * atomic_set_int(P, V)         (*(u_int *)(P) |= (V))
   50  * atomic_clear_int(P, V)       (*(u_int *)(P) &= ~(V))
   51  * atomic_add_int(P, V)         (*(u_int *)(P) += (V))
   52  * atomic_subtract_int(P, V)    (*(u_int *)(P) -= (V))
   53  * atomic_readandclear_int(P)   (return (*(u_int *)(P)); *(u_int *)(P) = 0;)
   54  *
   55  * atomic_set_long(P, V)        (*(u_long *)(P) |= (V))
   56  * atomic_clear_long(P, V)      (*(u_long *)(P) &= ~(V))
   57  * atomic_add_long(P, V)        (*(u_long *)(P) += (V))
   58  * atomic_subtract_long(P, V)   (*(u_long *)(P) -= (V))
   59  * atomic_readandclear_long(P)  (return (*(u_long *)(P)); *(u_long *)(P) = 0;)
   60  */
   61 
   62 /*
   63  * The above functions are expanded inline in the statically-linked
   64  * kernel.  Lock prefixes are generated if an SMP kernel is being
   65  * built.
   66  *
   67  * Kernel modules call real functions which are built into the kernel.
   68  * This allows kernel modules to be portable between UP and SMP systems.
   69  */
   70 #if defined(KLD_MODULE) || !defined(__GNUCLIKE_ASM)
   71 #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V)                     \
   72 void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
   73 
   74 int     atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src);
   75 int     atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src);
   76 u_int   atomic_fetchadd_int(volatile u_int *p, u_int v);
   77 u_long  atomic_fetchadd_long(volatile u_long *p, u_long v);
   78 
   79 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)                       \
   80 u_##TYPE        atomic_load_acq_##TYPE(volatile u_##TYPE *p);   \
   81 void            atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
   82 
   83 #else /* !KLD_MODULE && __GNUCLIKE_ASM */
   84 
   85 /*
   86  * For userland, always use lock prefixes so that the binaries will run
   87  * on both SMP and !SMP systems.
   88  */
   89 #if defined(SMP) || !defined(_KERNEL)
   90 #define MPLOCKED        "lock ; "
   91 #else
   92 #define MPLOCKED
   93 #endif
   94 
   95 /*
   96  * The assembly is volatilized to demark potential before-and-after side
   97  * effects if an interrupt or SMP collision were to occur.
   98  */
   99 #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V)             \
  100 static __inline void                                    \
  101 atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  102 {                                                       \
  103         __asm __volatile(MPLOCKED OP                    \
  104         : "=m" (*p)                                     \
  105         : CONS (V), "m" (*p));                          \
  106 }                                                       \
  107 struct __hack
  108 
  109 /*
  110  * Atomic compare and set, used by the mutex functions
  111  *
  112  * if (*dst == exp) *dst = src (all 32 bit words)
  113  *
  114  * Returns 0 on failure, non-zero on success
  115  */
  116 
  117 static __inline int
  118 atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
  119 {
  120         u_char res;
  121 
  122         __asm __volatile(
  123         "       " MPLOCKED "            "
  124         "       cmpxchgl %2,%1 ;        "
  125         "       sete    %0 ;            "
  126         "1:                             "
  127         "# atomic_cmpset_int"
  128         : "=a" (res),                   /* 0 */
  129           "=m" (*dst)                   /* 1 */
  130         : "r" (src),                    /* 2 */
  131           "a" (exp),                    /* 3 */
  132           "m" (*dst)                    /* 4 */
  133         : "memory");
  134 
  135         return (res);
  136 }
  137 
  138 static __inline int
  139 atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src)
  140 {
  141         u_char res;
  142 
  143         __asm __volatile(
  144         "       " MPLOCKED "            "
  145         "       cmpxchgq %2,%1 ;        "
  146         "       sete    %0 ;            "
  147         "1:                             "
  148         "# atomic_cmpset_long"
  149         : "=a" (res),                   /* 0 */
  150           "=m" (*dst)                   /* 1 */
  151         : "r" (src),                    /* 2 */
  152           "a" (exp),                    /* 3 */
  153           "m" (*dst)                    /* 4 */
  154         : "memory");
  155 
  156         return (res);
  157 }
  158 
  159 /*
  160  * Atomically add the value of v to the integer pointed to by p and return
  161  * the previous value of *p.
  162  */
  163 static __inline u_int
  164 atomic_fetchadd_int(volatile u_int *p, u_int v)
  165 {
  166 
  167         __asm __volatile(
  168         "       " MPLOCKED "            "
  169         "       xaddl   %0, %1 ;        "
  170         "# atomic_fetchadd_int"
  171         : "+r" (v),                     /* 0 (result) */
  172           "=m" (*p)                     /* 1 */
  173         : "m" (*p));                    /* 2 */
  174 
  175         return (v);
  176 }
  177 
  178 /*
  179  * Atomically add the value of v to the long integer pointed to by p and return
  180  * the previous value of *p.
  181  */
  182 static __inline u_long
  183 atomic_fetchadd_long(volatile u_long *p, u_long v)
  184 {
  185 
  186         __asm __volatile(
  187         "       " MPLOCKED "            "
  188         "       xaddq   %0, %1 ;        "
  189         "# atomic_fetchadd_long"
  190         : "+r" (v),                     /* 0 (result) */
  191           "=m" (*p)                     /* 1 */
  192         : "m" (*p));                    /* 2 */
  193 
  194         return (v);
  195 }
  196 
  197 #if defined(_KERNEL) && !defined(SMP)
  198 
  199 /*
  200  * We assume that a = b will do atomic loads and stores.  However, on a
  201  * PentiumPro or higher, reads may pass writes, so for that case we have
  202  * to use a serializing instruction (i.e. with LOCK) to do the load in
  203  * SMP kernels.  For UP kernels, however, the cache of the single processor
  204  * is always consistent, so we don't need any memory barriers.
  205  */
  206 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)               \
  207 static __inline u_##TYPE                                \
  208 atomic_load_acq_##TYPE(volatile u_##TYPE *p)            \
  209 {                                                       \
  210         return (*p);                                    \
  211 }                                                       \
  212                                                         \
  213 static __inline void                                    \
  214 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  215 {                                                       \
  216         *p = v;                                         \
  217 }                                                       \
  218 struct __hack
  219 
  220 #else /* !(_KERNEL && !SMP) */
  221 
  222 #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)               \
  223 static __inline u_##TYPE                                \
  224 atomic_load_acq_##TYPE(volatile u_##TYPE *p)            \
  225 {                                                       \
  226         u_##TYPE res;                                   \
  227                                                         \
  228         __asm __volatile(MPLOCKED LOP                   \
  229         : "=a" (res),                   /* 0 */         \
  230           "=m" (*p)                     /* 1 */         \
  231         : "m" (*p)                      /* 2 */         \
  232         : "memory");                                    \
  233                                                         \
  234         return (res);                                   \
  235 }                                                       \
  236                                                         \
  237 /*                                                      \
  238  * The XCHG instruction asserts LOCK automagically.     \
  239  */                                                     \
  240 static __inline void                                    \
  241 atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  242 {                                                       \
  243         __asm __volatile(SOP                            \
  244         : "=m" (*p),                    /* 0 */         \
  245           "+r" (v)                      /* 1 */         \
  246         : "m" (*p));                    /* 2 */         \
  247 }                                                       \
  248 struct __hack
  249 
  250 #endif /* _KERNEL && !SMP */
  251 
  252 #endif /* KLD_MODULE || !__GNUCLIKE_ASM */
  253 
  254 ATOMIC_ASM(set,      char,  "orb %b1,%0",  "iq",  v);
  255 ATOMIC_ASM(clear,    char,  "andb %b1,%0", "iq", ~v);
  256 ATOMIC_ASM(add,      char,  "addb %b1,%0", "iq",  v);
  257 ATOMIC_ASM(subtract, char,  "subb %b1,%0", "iq",  v);
  258 
  259 ATOMIC_ASM(set,      short, "orw %w1,%0",  "ir",  v);
  260 ATOMIC_ASM(clear,    short, "andw %w1,%0", "ir", ~v);
  261 ATOMIC_ASM(add,      short, "addw %w1,%0", "ir",  v);
  262 ATOMIC_ASM(subtract, short, "subw %w1,%0", "ir",  v);
  263 
  264 ATOMIC_ASM(set,      int,   "orl %1,%0",   "ir",  v);
  265 ATOMIC_ASM(clear,    int,   "andl %1,%0",  "ir", ~v);
  266 ATOMIC_ASM(add,      int,   "addl %1,%0",  "ir",  v);
  267 ATOMIC_ASM(subtract, int,   "subl %1,%0",  "ir",  v);
  268 
  269 ATOMIC_ASM(set,      long,  "orq %1,%0",   "ir",  v);
  270 ATOMIC_ASM(clear,    long,  "andq %1,%0",  "ir", ~v);
  271 ATOMIC_ASM(add,      long,  "addq %1,%0",  "ir",  v);
  272 ATOMIC_ASM(subtract, long,  "subq %1,%0",  "ir",  v);
  273 
  274 ATOMIC_STORE_LOAD(char, "cmpxchgb %b0,%1", "xchgb %b1,%0");
  275 ATOMIC_STORE_LOAD(short,"cmpxchgw %w0,%1", "xchgw %w1,%0");
  276 ATOMIC_STORE_LOAD(int,  "cmpxchgl %0,%1",  "xchgl %1,%0");
  277 ATOMIC_STORE_LOAD(long, "cmpxchgq %0,%1",  "xchgq %1,%0");
  278 
  279 #undef ATOMIC_ASM
  280 #undef ATOMIC_STORE_LOAD
  281 
  282 #ifndef WANT_FUNCTIONS
  283 
  284 /* Read the current value and store a zero in the destination. */
  285 #ifdef __GNUCLIKE_ASM
  286 
  287 static __inline u_int
  288 atomic_readandclear_int(volatile u_int *addr)
  289 {
  290         u_int res;
  291 
  292         res = 0;
  293         __asm __volatile(
  294         "       xchgl   %1,%0 ;         "
  295         "# atomic_readandclear_int"
  296         : "+r" (res),                   /* 0 */
  297           "=m" (*addr)                  /* 1 */
  298         : "m" (*addr));
  299 
  300         return (res);
  301 }
  302 
  303 static __inline u_long
  304 atomic_readandclear_long(volatile u_long *addr)
  305 {
  306         u_long res;
  307 
  308         res = 0;
  309         __asm __volatile(
  310         "       xchgq   %1,%0 ;         "
  311         "# atomic_readandclear_long"
  312         : "+r" (res),                   /* 0 */
  313           "=m" (*addr)                  /* 1 */
  314         : "m" (*addr));
  315 
  316         return (res);
  317 }
  318 
  319 #else /* !__GNUCLIKE_ASM */
  320 
  321 u_int   atomic_readandclear_int(volatile u_int *addr);
  322 u_long  atomic_readandclear_long(volatile u_long *addr);
  323 
  324 #endif /* __GNUCLIKE_ASM */
  325 
  326 /* Acquire and release variants are identical to the normal ones. */
  327 #define atomic_set_acq_char             atomic_set_char
  328 #define atomic_set_rel_char             atomic_set_char
  329 #define atomic_clear_acq_char           atomic_clear_char
  330 #define atomic_clear_rel_char           atomic_clear_char
  331 #define atomic_add_acq_char             atomic_add_char
  332 #define atomic_add_rel_char             atomic_add_char
  333 #define atomic_subtract_acq_char        atomic_subtract_char
  334 #define atomic_subtract_rel_char        atomic_subtract_char
  335 
  336 #define atomic_set_acq_short            atomic_set_short
  337 #define atomic_set_rel_short            atomic_set_short
  338 #define atomic_clear_acq_short          atomic_clear_short
  339 #define atomic_clear_rel_short          atomic_clear_short
  340 #define atomic_add_acq_short            atomic_add_short
  341 #define atomic_add_rel_short            atomic_add_short
  342 #define atomic_subtract_acq_short       atomic_subtract_short
  343 #define atomic_subtract_rel_short       atomic_subtract_short
  344 
  345 #define atomic_set_acq_int              atomic_set_int
  346 #define atomic_set_rel_int              atomic_set_int
  347 #define atomic_clear_acq_int            atomic_clear_int
  348 #define atomic_clear_rel_int            atomic_clear_int
  349 #define atomic_add_acq_int              atomic_add_int
  350 #define atomic_add_rel_int              atomic_add_int
  351 #define atomic_subtract_acq_int         atomic_subtract_int
  352 #define atomic_subtract_rel_int         atomic_subtract_int
  353 #define atomic_cmpset_acq_int           atomic_cmpset_int
  354 #define atomic_cmpset_rel_int           atomic_cmpset_int
  355 
  356 #define atomic_set_acq_long             atomic_set_long
  357 #define atomic_set_rel_long             atomic_set_long
  358 #define atomic_clear_acq_long           atomic_clear_long
  359 #define atomic_clear_rel_long           atomic_clear_long
  360 #define atomic_add_acq_long             atomic_add_long
  361 #define atomic_add_rel_long             atomic_add_long
  362 #define atomic_subtract_acq_long        atomic_subtract_long
  363 #define atomic_subtract_rel_long        atomic_subtract_long
  364 #define atomic_cmpset_acq_long          atomic_cmpset_long
  365 #define atomic_cmpset_rel_long          atomic_cmpset_long
  366 
  367 /* Operations on 8-bit bytes. */
  368 #define atomic_set_8            atomic_set_char
  369 #define atomic_set_acq_8        atomic_set_acq_char
  370 #define atomic_set_rel_8        atomic_set_rel_char
  371 #define atomic_clear_8          atomic_clear_char
  372 #define atomic_clear_acq_8      atomic_clear_acq_char
  373 #define atomic_clear_rel_8      atomic_clear_rel_char
  374 #define atomic_add_8            atomic_add_char
  375 #define atomic_add_acq_8        atomic_add_acq_char
  376 #define atomic_add_rel_8        atomic_add_rel_char
  377 #define atomic_subtract_8       atomic_subtract_char
  378 #define atomic_subtract_acq_8   atomic_subtract_acq_char
  379 #define atomic_subtract_rel_8   atomic_subtract_rel_char
  380 #define atomic_load_acq_8       atomic_load_acq_char
  381 #define atomic_store_rel_8      atomic_store_rel_char
  382 
  383 /* Operations on 16-bit words. */
  384 #define atomic_set_16           atomic_set_short
  385 #define atomic_set_acq_16       atomic_set_acq_short
  386 #define atomic_set_rel_16       atomic_set_rel_short
  387 #define atomic_clear_16         atomic_clear_short
  388 #define atomic_clear_acq_16     atomic_clear_acq_short
  389 #define atomic_clear_rel_16     atomic_clear_rel_short
  390 #define atomic_add_16           atomic_add_short
  391 #define atomic_add_acq_16       atomic_add_acq_short
  392 #define atomic_add_rel_16       atomic_add_rel_short
  393 #define atomic_subtract_16      atomic_subtract_short
  394 #define atomic_subtract_acq_16  atomic_subtract_acq_short
  395 #define atomic_subtract_rel_16  atomic_subtract_rel_short
  396 #define atomic_load_acq_16      atomic_load_acq_short
  397 #define atomic_store_rel_16     atomic_store_rel_short
  398 
  399 /* Operations on 32-bit double words. */
  400 #define atomic_set_32           atomic_set_int
  401 #define atomic_set_acq_32       atomic_set_acq_int
  402 #define atomic_set_rel_32       atomic_set_rel_int
  403 #define atomic_clear_32         atomic_clear_int
  404 #define atomic_clear_acq_32     atomic_clear_acq_int
  405 #define atomic_clear_rel_32     atomic_clear_rel_int
  406 #define atomic_add_32           atomic_add_int
  407 #define atomic_add_acq_32       atomic_add_acq_int
  408 #define atomic_add_rel_32       atomic_add_rel_int
  409 #define atomic_subtract_32      atomic_subtract_int
  410 #define atomic_subtract_acq_32  atomic_subtract_acq_int
  411 #define atomic_subtract_rel_32  atomic_subtract_rel_int
  412 #define atomic_load_acq_32      atomic_load_acq_int
  413 #define atomic_store_rel_32     atomic_store_rel_int
  414 #define atomic_cmpset_32        atomic_cmpset_int
  415 #define atomic_cmpset_acq_32    atomic_cmpset_acq_int
  416 #define atomic_cmpset_rel_32    atomic_cmpset_rel_int
  417 #define atomic_readandclear_32  atomic_readandclear_int
  418 #define atomic_fetchadd_32      atomic_fetchadd_int
  419 
  420 /* Operations on 64-bit quad words. */
  421 #define atomic_set_64           atomic_set_long
  422 #define atomic_set_acq_64       atomic_set_acq_long
  423 #define atomic_set_rel_64       atomic_set_rel_long
  424 #define atomic_clear_64         atomic_clear_long
  425 #define atomic_clear_acq_64     atomic_clear_acq_long
  426 #define atomic_clear_rel_64     atomic_clear_rel_long
  427 #define atomic_add_64           atomic_add_long
  428 #define atomic_add_acq_64       atomic_add_acq_long
  429 #define atomic_add_rel_64       atomic_add_rel_long
  430 #define atomic_subtract_64      atomic_subtract_long
  431 #define atomic_subtract_acq_64  atomic_subtract_acq_long
  432 #define atomic_subtract_rel_64  atomic_subtract_rel_long
  433 #define atomic_load_acq_64      atomic_load_acq_long
  434 #define atomic_store_rel_64     atomic_store_rel_long
  435 #define atomic_cmpset_64        atomic_cmpset_long
  436 #define atomic_cmpset_acq_64    atomic_cmpset_acq_long
  437 #define atomic_cmpset_rel_64    atomic_cmpset_rel_long
  438 #define atomic_readandclear_64  atomic_readandclear_long
  439 
  440 /* Operations on pointers. */
  441 #define atomic_set_ptr          atomic_set_long
  442 #define atomic_set_acq_ptr      atomic_set_acq_long
  443 #define atomic_set_rel_ptr      atomic_set_rel_long
  444 #define atomic_clear_ptr        atomic_clear_long
  445 #define atomic_clear_acq_ptr    atomic_clear_acq_long
  446 #define atomic_clear_rel_ptr    atomic_clear_rel_long
  447 #define atomic_add_ptr          atomic_add_long
  448 #define atomic_add_acq_ptr      atomic_add_acq_long
  449 #define atomic_add_rel_ptr      atomic_add_rel_long
  450 #define atomic_subtract_ptr     atomic_subtract_long
  451 #define atomic_subtract_acq_ptr atomic_subtract_acq_long
  452 #define atomic_subtract_rel_ptr atomic_subtract_rel_long
  453 #define atomic_load_acq_ptr     atomic_load_acq_long
  454 #define atomic_store_rel_ptr    atomic_store_rel_long
  455 #define atomic_cmpset_ptr       atomic_cmpset_long
  456 #define atomic_cmpset_acq_ptr   atomic_cmpset_acq_long
  457 #define atomic_cmpset_rel_ptr   atomic_cmpset_rel_long
  458 #define atomic_readandclear_ptr atomic_readandclear_long
  459 
  460 #endif /* !WANT_FUNCTIONS */
  461 
  462 #endif /* !_MACHINE_ATOMIC_H_ */

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