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

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
      * 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: head/sys/i386/include/counter.h 343723 2019-02-03 21:28:58Z kib $
     */
    
    #ifndef __MACHINE_COUNTER_H__
    #define __MACHINE_COUNTER_H__
    
    #include <sys/pcpu.h>
    #ifdef INVARIANTS
    #include <sys/proc.h>
    #endif
    #include <machine/md_var.h>
    #include <machine/specialreg.h>
    
    extern struct pcpu __pcpu[];
    
    #define EARLY_COUNTER   &__pcpu[0].pc_early_dummy_counter
    
    #define counter_enter() do {                            \
            if ((cpu_feature & CPUID_CX8) == 0)             \
                    critical_enter();                       \
    } while (0)
    
    #define counter_exit()  do {                            \
            if ((cpu_feature & CPUID_CX8) == 0)             \
                    critical_exit();                        \
    } while (0)
    
    static inline void
    counter_64_inc_8b(uint64_t *p, int64_t inc)
    {
    
            __asm __volatile(
            "movl   %%fs:(%%esi),%%eax\n\t"
            "movl   %%fs:4(%%esi),%%edx\n"
    "1:\n\t"
            "movl   %%eax,%%ebx\n\t"
            "movl   %%edx,%%ecx\n\t"
            "addl   (%%edi),%%ebx\n\t"
            "adcl   4(%%edi),%%ecx\n\t"
            "cmpxchg8b %%fs:(%%esi)\n\t"
            "jnz    1b"
            :
            : "S" ((char *)p - (char *)&__pcpu[0]), "D" (&inc)
            : "memory", "cc", "eax", "edx", "ebx", "ecx");
    }
    
    #ifdef IN_SUBR_COUNTER_C
    struct counter_u64_fetch_cx8_arg {
            uint64_t res;
            uint64_t *p;
    };
    
    static uint64_t
    counter_u64_read_one_8b(uint64_t *p)
    {
            uint32_t res_lo, res_high;
    
            __asm __volatile(
            "movl   %%eax,%%ebx\n\t"
            "movl   %%edx,%%ecx\n\t"
            "cmpxchg8b      (%2)"
            : "=a" (res_lo), "=d"(res_high)
            : "SD" (p)
            : "cc", "ebx", "ecx");
            return (res_lo + ((uint64_t)res_high << 32));
    }
    
    static void
    counter_u64_fetch_cx8_one(void *arg1)
    {
            struct counter_u64_fetch_cx8_arg *arg;
            uint64_t val;
   
           arg = arg1;
           val = counter_u64_read_one_8b((uint64_t *)((char *)arg->p +
               UMA_PCPU_ALLOC_SIZE * PCPU_GET(cpuid)));
           atomic_add_64(&arg->res, val);
   }
   
   static inline uint64_t
   counter_u64_fetch_inline(uint64_t *p)
   {
           struct counter_u64_fetch_cx8_arg arg;
           uint64_t res;
           int i;
   
           res = 0;
           if ((cpu_feature & CPUID_CX8) == 0) {
                   /*
                    * The machines without cmpxchg8b are not SMP.
                    * Disabling the preemption provides atomicity of the
                    * counter reading, since update is done in the
                    * critical section as well.
                    */
                   critical_enter();
                   CPU_FOREACH(i) {
                           res += *(uint64_t *)((char *)p +
                               UMA_PCPU_ALLOC_SIZE * i);
                   }
                   critical_exit();
           } else {
                   arg.p = p;
                   arg.res = 0;
                   smp_rendezvous(NULL, counter_u64_fetch_cx8_one, NULL, &arg);
                   res = arg.res;
           }
           return (res);
   }
   
   static inline void
   counter_u64_zero_one_8b(uint64_t *p)
   {
   
           __asm __volatile(
           "movl   (%0),%%eax\n\t"
           "movl   4(%0),%%edx\n"
           "xorl   %%ebx,%%ebx\n\t"
           "xorl   %%ecx,%%ecx\n\t"
   "1:\n\t"
           "cmpxchg8b      (%0)\n\t"
           "jnz    1b"
           :
           : "SD" (p)
           : "memory", "cc", "eax", "edx", "ebx", "ecx");
   }
   
   static void
   counter_u64_zero_one_cpu(void *arg)
   {
           uint64_t *p;
   
           p = (uint64_t *)((char *)arg + UMA_PCPU_ALLOC_SIZE * PCPU_GET(cpuid));
           counter_u64_zero_one_8b(p);
   }
   
   static inline void
   counter_u64_zero_inline(counter_u64_t c)
   {
           int i;
   
           if ((cpu_feature & CPUID_CX8) == 0) {
                   critical_enter();
                   CPU_FOREACH(i)
                           *(uint64_t *)((char *)c + UMA_PCPU_ALLOC_SIZE * i) = 0;
                   critical_exit();
           } else {
                   smp_rendezvous(smp_no_rendezvous_barrier,
                       counter_u64_zero_one_cpu, smp_no_rendezvous_barrier, c);
           }
   }
   #endif
   
   #define counter_u64_add_protected(c, inc)       do {    \
           if ((cpu_feature & CPUID_CX8) == 0) {           \
                   CRITICAL_ASSERT(curthread);             \
                   *(uint64_t *)zpcpu_get(c) += (inc);     \
           } else                                          \
                   counter_64_inc_8b((c), (inc));          \
   } while (0)
   
   static inline void
   counter_u64_add(counter_u64_t c, int64_t inc)
   {
   
           if ((cpu_feature & CPUID_CX8) == 0) {
                   critical_enter();
                   *(uint64_t *)zpcpu_get(c) += inc;
                   critical_exit();
           } else {
                   counter_64_inc_8b(c, inc);
           }
   }
   
   #endif  /* ! __MACHINE_COUNTER_H__ */

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