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/kern/subr_atomic64.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2019 Justin Hibbits
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  * $FreeBSD$
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/lock.h>
   34 #include <sys/mutex.h>
   35 #include <sys/smp.h>
   36 #include <sys/systm.h>
   37 
   38 #include <machine/atomic.h>
   39 #include <machine/param.h>
   40 
   41 #include <vm/vm.h>
   42 #include <vm/pmap.h>
   43 
   44 enum {
   45     ATOMIC64_ADD,
   46     ATOMIC64_CLEAR,
   47     ATOMIC64_CMPSET,
   48     ATOMIC64_FCMPSET,
   49     ATOMIC64_FETCHADD,
   50     ATOMIC64_LOAD,
   51     ATOMIC64_SET,
   52     ATOMIC64_SUBTRACT,
   53     ATOMIC64_STORE,
   54     ATOMIC64_SWAP
   55 };
   56 
   57 #ifdef _KERNEL
   58 #ifdef SMP
   59 
   60 #define A64_POOL_SIZE   MAXCPU
   61 /* Estimated size of a cacheline */
   62 #define CACHE_ALIGN     CACHE_LINE_SIZE
   63 static struct mtx a64_mtx_pool[A64_POOL_SIZE];
   64 
   65 #define GET_MUTEX(p) \
   66     (&a64_mtx_pool[(pmap_kextract((vm_offset_t)p) / CACHE_ALIGN) % (A64_POOL_SIZE)])
   67 
   68 #define LOCK_A64()                      \
   69     struct mtx *_amtx = GET_MUTEX(p);   \
   70     if (smp_started) mtx_lock(_amtx)
   71 
   72 #define UNLOCK_A64()    if (smp_started) mtx_unlock(_amtx)
   73 
   74 #else   /* !SMP */
   75 
   76 #define LOCK_A64()      { register_t s = intr_disable()
   77 #define UNLOCK_A64()    intr_restore(s); }
   78 
   79 #endif  /* SMP */
   80 
   81 #define ATOMIC64_EMU_UN(op, rt, block, ret) \
   82     rt \
   83     atomic_##op##_64(volatile uint64_t *p) {                    \
   84         uint64_t tmp __unused;                                  \
   85         LOCK_A64();                                             \
   86         block;                                                  \
   87         UNLOCK_A64();                                           \
   88         ret; } struct hack
   89 
   90 #define ATOMIC64_EMU_BIN(op, rt, block, ret) \
   91     rt \
   92     atomic_##op##_64(volatile uint64_t *p, uint64_t v) {        \
   93         uint64_t tmp __unused;                                  \
   94         LOCK_A64();                                             \
   95         block;                                                  \
   96         UNLOCK_A64();                                           \
   97         ret; } struct hack
   98 
   99 ATOMIC64_EMU_BIN(add, void, (*p = *p + v), return);
  100 ATOMIC64_EMU_BIN(clear, void, *p &= ~v, return);
  101 ATOMIC64_EMU_BIN(fetchadd, uint64_t, (*p = *p + v, v = *p - v), return (v));
  102 ATOMIC64_EMU_UN(load, uint64_t, (tmp = *p), return (tmp));
  103 ATOMIC64_EMU_BIN(set, void, *p |= v, return);
  104 ATOMIC64_EMU_BIN(subtract, void, (*p = *p - v), return);
  105 ATOMIC64_EMU_BIN(store, void, *p = v, return);
  106 ATOMIC64_EMU_BIN(swap, uint64_t, tmp = *p; *p = v; v = tmp, return(v));
  107 
  108 int atomic_cmpset_64(volatile uint64_t *p, uint64_t old, uint64_t new)
  109 {
  110         uint64_t tmp;
  111 
  112         LOCK_A64();
  113         tmp = *p;
  114         if (tmp == old)
  115                 *p = new;
  116         UNLOCK_A64();
  117 
  118         return (tmp == old);
  119 }
  120 
  121 int atomic_fcmpset_64(volatile uint64_t *p, uint64_t *old, uint64_t new)
  122 {
  123         uint64_t tmp, tmp_old;
  124 
  125         LOCK_A64();
  126         tmp = *p;
  127         tmp_old = *old;
  128         if (tmp == tmp_old)
  129                 *p = new;
  130         else
  131                 *old = tmp;
  132         UNLOCK_A64();
  133 
  134         return (tmp == tmp_old);
  135 }
  136 
  137 #ifdef SMP
  138 static void
  139 atomic64_mtxinit(void *x __unused)
  140 {
  141         int i;
  142 
  143         for (i = 0; i < A64_POOL_SIZE; i++)
  144                 mtx_init(&a64_mtx_pool[i], "atomic64 mutex", NULL, MTX_DEF);
  145 }
  146 
  147 SYSINIT(atomic64_mtxinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, atomic64_mtxinit, NULL);
  148 #endif  /* SMP */
  149 
  150 #endif  /* _KERNEL */

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