FreeBSD/Linux Kernel Cross Reference
sys/amd64/include/atomic.h

     /*-
      * Copyright (c) 1998 Doug Rabson
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    #ifndef _MACHINE_ATOMIC_H_
    #define _MACHINE_ATOMIC_H_
    
    #ifndef _SYS_CDEFS_H_
    #error this file needs sys/cdefs.h as a prerequisite
    #endif
    
    /*
     * Various simple operations on memory, each of which is atomic in the
     * presence of interrupts and multiple processors.
     *
     * atomic_set_char(P, V)        (*(u_char *)(P) |= (V))
     * atomic_clear_char(P, V)      (*(u_char *)(P) &= ~(V))
     * atomic_add_char(P, V)        (*(u_char *)(P) += (V))
     * atomic_subtract_char(P, V)   (*(u_char *)(P) -= (V))
     *
     * atomic_set_short(P, V)       (*(u_short *)(P) |= (V))
     * atomic_clear_short(P, V)     (*(u_short *)(P) &= ~(V))
     * atomic_add_short(P, V)       (*(u_short *)(P) += (V))
     * atomic_subtract_short(P, V)  (*(u_short *)(P) -= (V))
     *
     * atomic_set_int(P, V)         (*(u_int *)(P) |= (V))
     * atomic_clear_int(P, V)       (*(u_int *)(P) &= ~(V))
     * atomic_add_int(P, V)         (*(u_int *)(P) += (V))
     * atomic_subtract_int(P, V)    (*(u_int *)(P) -= (V))
     * atomic_readandclear_int(P)   (return (*(u_int *)(P)); *(u_int *)(P) = 0;)
     *
     * atomic_set_long(P, V)        (*(u_long *)(P) |= (V))
     * atomic_clear_long(P, V)      (*(u_long *)(P) &= ~(V))
     * atomic_add_long(P, V)        (*(u_long *)(P) += (V))
     * atomic_subtract_long(P, V)   (*(u_long *)(P) -= (V))
     * atomic_readandclear_long(P)  (return (*(u_long *)(P)); *(u_long *)(P) = 0;)
     */
    
    /*
     * The above functions are expanded inline in the statically-linked
     * kernel.  Lock prefixes are generated if an SMP kernel is being
     * built.
     *
     * Kernel modules call real functions which are built into the kernel.
     * This allows kernel modules to be portable between UP and SMP systems.
     */
    #if defined(KLD_MODULE) || !defined(__GNUCLIKE_ASM)
    #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V)                     \
    void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
    
    int     atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src);
    int     atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src);
    u_int   atomic_fetchadd_int(volatile u_int *p, u_int v);
    
    #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)                       \
    u_##TYPE        atomic_load_acq_##TYPE(volatile u_##TYPE *p);   \
    void            atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
    
    #else /* !KLD_MODULE && __GNUCLIKE_ASM */
    
    /*
     * For userland, always use lock prefixes so that the binaries will run
     * on both SMP and !SMP systems.
     */
    #if defined(SMP) || !defined(_KERNEL)
    #define MPLOCKED        "lock ; "
    #else
    #define MPLOCKED
    #endif
    
    /*
     * The assembly is volatilized to demark potential before-and-after side
     * effects if an interrupt or SMP collision were to occur.
     */
    #define ATOMIC_ASM(NAME, TYPE, OP, CONS, V)             \
    static __inline void                                    \
   atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
   {                                                       \
           __asm __volatile(MPLOCKED OP                    \
           : "=m" (*p)                                     \
           : CONS (V), "m" (*p));                          \
   }                                                       \
   struct __hack
   
   /*
    * Atomic compare and set, used by the mutex functions
    *
    * if (*dst == exp) *dst = src (all 32 bit words)
    *
    * Returns 0 on failure, non-zero on success
    */
   
   static __inline int
   atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
   {
           u_char res;
   
           __asm __volatile(
           "       " MPLOCKED "            "
           "       cmpxchgl %2,%1 ;        "
           "       sete    %0 ;            "
           "1:                             "
           "# atomic_cmpset_int"
           : "=a" (res),                   /* 0 */
             "=m" (*dst)                   /* 1 */
           : "r" (src),                    /* 2 */
             "a" (exp),                    /* 3 */
             "m" (*dst)                    /* 4 */
           : "memory");
   
           return (res);
   }
   
   static __inline int
   atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src)
   {
           u_char res;
   
           __asm __volatile(
           "       " MPLOCKED "            "
           "       cmpxchgq %2,%1 ;        "
           "       sete    %0 ;            "
           "1:                             "
           "# atomic_cmpset_long"
           : "=a" (res),                   /* 0 */
             "=m" (*dst)                   /* 1 */
           : "r" (src),                    /* 2 */
             "a" (exp),                    /* 3 */
             "m" (*dst)                    /* 4 */
           : "memory");
   
           return (res);
   }
   
   /*
    * Atomically add the value of v to the integer pointed to by p and return
    * the previous value of *p.
    */
   static __inline u_int
   atomic_fetchadd_int(volatile u_int *p, u_int v)
   {
   
           __asm __volatile(
           "       " MPLOCKED "            "
           "       xaddl   %0, %1 ;        "
           "# atomic_fetchadd_int"
           : "+r" (v),                     /* 0 (result) */
             "=m" (*p)                     /* 1 */
           : "m" (*p));                    /* 2 */
   
           return (v);
   }
   
   #if defined(_KERNEL) && !defined(SMP)
   
   /*
    * We assume that a = b will do atomic loads and stores.  However, on a
    * PentiumPro or higher, reads may pass writes, so for that case we have
    * to use a serializing instruction (i.e. with LOCK) to do the load in
    * SMP kernels.  For UP kernels, however, the cache of the single processor
    * is always consistent, so we don't need any memory barriers.
    */
   #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)               \
   static __inline u_##TYPE                                \
   atomic_load_acq_##TYPE(volatile u_##TYPE *p)            \
   {                                                       \
           return (*p);                                    \
   }                                                       \
                                                           \
   static __inline void                                    \
   atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
   {                                                       \
           *p = v;                                         \
   }                                                       \
   struct __hack
   
   #else /* !(_KERNEL && !SMP) */
   
   #define ATOMIC_STORE_LOAD(TYPE, LOP, SOP)               \
   static __inline u_##TYPE                                \
   atomic_load_acq_##TYPE(volatile u_##TYPE *p)            \
   {                                                       \
           u_##TYPE res;                                   \
                                                           \
           __asm __volatile(MPLOCKED LOP                   \
           : "=a" (res),                   /* 0 */         \
             "=m" (*p)                     /* 1 */         \
           : "m" (*p)                      /* 2 */         \
           : "memory");                                    \
                                                           \
           return (res);                                   \
   }                                                       \
                                                           \
   /*                                                      \
    * The XCHG instruction asserts LOCK automagically.     \
    */                                                     \
   static __inline void                                    \
   atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
   {                                                       \
           __asm __volatile(SOP                            \
           : "=m" (*p),                    /* 0 */         \
             "+r" (v)                      /* 1 */         \
           : "m" (*p));                    /* 2 */         \
   }                                                       \
   struct __hack
   
   #endif /* _KERNEL && !SMP */
   
   #endif /* KLD_MODULE || !__GNUCLIKE_ASM */
   
   ATOMIC_ASM(set,      char,  "orb %b1,%0",  "iq",  v);
   ATOMIC_ASM(clear,    char,  "andb %b1,%0", "iq", ~v);
   ATOMIC_ASM(add,      char,  "addb %b1,%0", "iq",  v);
   ATOMIC_ASM(subtract, char,  "subb %b1,%0", "iq",  v);
   
   ATOMIC_ASM(set,      short, "orw %w1,%0",  "ir",  v);
   ATOMIC_ASM(clear,    short, "andw %w1,%0", "ir", ~v);
   ATOMIC_ASM(add,      short, "addw %w1,%0", "ir",  v);
   ATOMIC_ASM(subtract, short, "subw %w1,%0", "ir",  v);
   
   ATOMIC_ASM(set,      int,   "orl %1,%0",   "ir",  v);
   ATOMIC_ASM(clear,    int,   "andl %1,%0",  "ir", ~v);
   ATOMIC_ASM(add,      int,   "addl %1,%0",  "ir",  v);
   ATOMIC_ASM(subtract, int,   "subl %1,%0",  "ir",  v);
   
   ATOMIC_ASM(set,      long,  "orq %1,%0",   "ir",  v);
   ATOMIC_ASM(clear,    long,  "andq %1,%0",  "ir", ~v);
   ATOMIC_ASM(add,      long,  "addq %1,%0",  "ir",  v);
   ATOMIC_ASM(subtract, long,  "subq %1,%0",  "ir",  v);
   
   ATOMIC_STORE_LOAD(char, "cmpxchgb %b0,%1", "xchgb %b1,%0");
   ATOMIC_STORE_LOAD(short,"cmpxchgw %w0,%1", "xchgw %w1,%0");
   ATOMIC_STORE_LOAD(int,  "cmpxchgl %0,%1",  "xchgl %1,%0");
   ATOMIC_STORE_LOAD(long, "cmpxchgq %0,%1",  "xchgq %1,%0");
   
   #undef ATOMIC_ASM
   #undef ATOMIC_STORE_LOAD
   
   #ifndef WANT_FUNCTIONS
   
   /* Read the current value and store a zero in the destination. */
   #ifdef __GNUCLIKE_ASM
   
   static __inline u_int
   atomic_readandclear_int(volatile u_int *addr)
   {
           u_int res;
   
           res = 0;
           __asm __volatile(
           "       xchgl   %1,%0 ;         "
           "# atomic_readandclear_int"
           : "+r" (res),                   /* 0 */
             "=m" (*addr)                  /* 1 */
           : "m" (*addr));
   
           return (res);
   }
   
   static __inline u_long
   atomic_readandclear_long(volatile u_long *addr)
   {
           u_long res;
   
           res = 0;
           __asm __volatile(
           "       xchgq   %1,%0 ;         "
           "# atomic_readandclear_long"
           : "+r" (res),                   /* 0 */
             "=m" (*addr)                  /* 1 */
           : "m" (*addr));
   
           return (res);
   }
   
   #else /* !__GNUCLIKE_ASM */
   
   u_int   atomic_readandclear_int(volatile u_int *addr);
   u_long  atomic_readandclear_long(volatile u_long *addr);
   
   #endif /* __GNUCLIKE_ASM */
   
   /* Acquire and release variants are identical to the normal ones. */
   #define atomic_set_acq_char             atomic_set_char
   #define atomic_set_rel_char             atomic_set_char
   #define atomic_clear_acq_char           atomic_clear_char
   #define atomic_clear_rel_char           atomic_clear_char
   #define atomic_add_acq_char             atomic_add_char
   #define atomic_add_rel_char             atomic_add_char
   #define atomic_subtract_acq_char        atomic_subtract_char
   #define atomic_subtract_rel_char        atomic_subtract_char
   
   #define atomic_set_acq_short            atomic_set_short
   #define atomic_set_rel_short            atomic_set_short
   #define atomic_clear_acq_short          atomic_clear_short
   #define atomic_clear_rel_short          atomic_clear_short
   #define atomic_add_acq_short            atomic_add_short
   #define atomic_add_rel_short            atomic_add_short
   #define atomic_subtract_acq_short       atomic_subtract_short
   #define atomic_subtract_rel_short       atomic_subtract_short
   
   #define atomic_set_acq_int              atomic_set_int
   #define atomic_set_rel_int              atomic_set_int
   #define atomic_clear_acq_int            atomic_clear_int
   #define atomic_clear_rel_int            atomic_clear_int
   #define atomic_add_acq_int              atomic_add_int
   #define atomic_add_rel_int              atomic_add_int
   #define atomic_subtract_acq_int         atomic_subtract_int
   #define atomic_subtract_rel_int         atomic_subtract_int
   #define atomic_cmpset_acq_int           atomic_cmpset_int
   #define atomic_cmpset_rel_int           atomic_cmpset_int
   
   #define atomic_set_acq_long             atomic_set_long
   #define atomic_set_rel_long             atomic_set_long
   #define atomic_clear_acq_long           atomic_clear_long
   #define atomic_clear_rel_long           atomic_clear_long
   #define atomic_add_acq_long             atomic_add_long
   #define atomic_add_rel_long             atomic_add_long
   #define atomic_subtract_acq_long        atomic_subtract_long
   #define atomic_subtract_rel_long        atomic_subtract_long
   #define atomic_cmpset_acq_long          atomic_cmpset_long
   #define atomic_cmpset_rel_long          atomic_cmpset_long
   
   /* Operations on 8-bit bytes. */
   #define atomic_set_8            atomic_set_char
   #define atomic_set_acq_8        atomic_set_acq_char
   #define atomic_set_rel_8        atomic_set_rel_char
   #define atomic_clear_8          atomic_clear_char
   #define atomic_clear_acq_8      atomic_clear_acq_char
   #define atomic_clear_rel_8      atomic_clear_rel_char
   #define atomic_add_8            atomic_add_char
   #define atomic_add_acq_8        atomic_add_acq_char
   #define atomic_add_rel_8        atomic_add_rel_char
   #define atomic_subtract_8       atomic_subtract_char
   #define atomic_subtract_acq_8   atomic_subtract_acq_char
   #define atomic_subtract_rel_8   atomic_subtract_rel_char
   #define atomic_load_acq_8       atomic_load_acq_char
   #define atomic_store_rel_8      atomic_store_rel_char
   
   /* Operations on 16-bit words. */
   #define atomic_set_16           atomic_set_short
   #define atomic_set_acq_16       atomic_set_acq_short
   #define atomic_set_rel_16       atomic_set_rel_short
   #define atomic_clear_16         atomic_clear_short
   #define atomic_clear_acq_16     atomic_clear_acq_short
   #define atomic_clear_rel_16     atomic_clear_rel_short
   #define atomic_add_16           atomic_add_short
   #define atomic_add_acq_16       atomic_add_acq_short
   #define atomic_add_rel_16       atomic_add_rel_short
   #define atomic_subtract_16      atomic_subtract_short
   #define atomic_subtract_acq_16  atomic_subtract_acq_short
   #define atomic_subtract_rel_16  atomic_subtract_rel_short
   #define atomic_load_acq_16      atomic_load_acq_short
   #define atomic_store_rel_16     atomic_store_rel_short
   
   /* Operations on 32-bit double words. */
   #define atomic_set_32           atomic_set_int
   #define atomic_set_acq_32       atomic_set_acq_int
   #define atomic_set_rel_32       atomic_set_rel_int
   #define atomic_clear_32         atomic_clear_int
   #define atomic_clear_acq_32     atomic_clear_acq_int
   #define atomic_clear_rel_32     atomic_clear_rel_int
   #define atomic_add_32           atomic_add_int
   #define atomic_add_acq_32       atomic_add_acq_int
   #define atomic_add_rel_32       atomic_add_rel_int
   #define atomic_subtract_32      atomic_subtract_int
   #define atomic_subtract_acq_32  atomic_subtract_acq_int
   #define atomic_subtract_rel_32  atomic_subtract_rel_int
   #define atomic_load_acq_32      atomic_load_acq_int
   #define atomic_store_rel_32     atomic_store_rel_int
   #define atomic_cmpset_32        atomic_cmpset_int
   #define atomic_cmpset_acq_32    atomic_cmpset_acq_int
   #define atomic_cmpset_rel_32    atomic_cmpset_rel_int
   #define atomic_readandclear_32  atomic_readandclear_int
   #define atomic_fetchadd_32      atomic_fetchadd_int
   
   /* Operations on 64-bit quad words. */
   #define atomic_set_64           atomic_set_long
   #define atomic_set_acq_64       atomic_set_acq_long
   #define atomic_set_rel_64       atomic_set_rel_long
   #define atomic_clear_64         atomic_clear_long
   #define atomic_clear_acq_64     atomic_clear_acq_long
   #define atomic_clear_rel_64     atomic_clear_rel_long
   #define atomic_add_64           atomic_add_long
   #define atomic_add_acq_64       atomic_add_acq_long
   #define atomic_add_rel_64       atomic_add_rel_long
   #define atomic_subtract_64      atomic_subtract_long
   #define atomic_subtract_acq_64  atomic_subtract_acq_long
   #define atomic_subtract_rel_64  atomic_subtract_rel_long
   #define atomic_load_acq_64      atomic_load_acq_long
   #define atomic_store_rel_64     atomic_store_rel_long
   #define atomic_cmpset_64        atomic_cmpset_long
   #define atomic_cmpset_acq_64    atomic_cmpset_acq_long
   #define atomic_cmpset_rel_64    atomic_cmpset_rel_long
   #define atomic_readandclear_64  atomic_readandclear_long
   
   /* Operations on pointers. */
   #define atomic_set_ptr          atomic_set_long
   #define atomic_set_acq_ptr      atomic_set_acq_long
   #define atomic_set_rel_ptr      atomic_set_rel_long
   #define atomic_clear_ptr        atomic_clear_long
   #define atomic_clear_acq_ptr    atomic_clear_acq_long
   #define atomic_clear_rel_ptr    atomic_clear_rel_long
   #define atomic_add_ptr          atomic_add_long
   #define atomic_add_acq_ptr      atomic_add_acq_long
   #define atomic_add_rel_ptr      atomic_add_rel_long
   #define atomic_subtract_ptr     atomic_subtract_long
   #define atomic_subtract_acq_ptr atomic_subtract_acq_long
   #define atomic_subtract_rel_ptr atomic_subtract_rel_long
   #define atomic_load_acq_ptr     atomic_load_acq_long
   #define atomic_store_rel_ptr    atomic_store_rel_long
   #define atomic_cmpset_ptr       atomic_cmpset_long
   #define atomic_cmpset_acq_ptr   atomic_cmpset_acq_long
   #define atomic_cmpset_rel_ptr   atomic_cmpset_rel_long
   #define atomic_readandclear_ptr atomic_readandclear_long
   
   #endif /* !WANT_FUNCTIONS */
   
   #endif /* !_MACHINE_ATOMIC_H_ */

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