9aafc7c052
This is a lock-based emulation of 64-bit atomics for kernel use, split off from an earlier patch by jhibbits. This is needed to unblock future improvements that reduce the need for locking on 64-bit platforms by using atomic updates. The implementation allows for future integration with userland atomic64, but as that implies going through sysarch for every use, the current status quo of userland doing its own locking may be for the best. Submitted by: jhibbits (original patch), kevans (mips bits) Reviewed by: jhibbits, jeff, kevans Differential Revision: https://reviews.freebsd.org/D22976
124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
/*-
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* Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/atomic.h>
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#if !defined(__LP64__) && !defined(__mips_n32) && \
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!defined(ARM_HAVE_ATOMIC64) && !defined(I386_HAVE_ATOMIC64) && \
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!defined(HAS_EMULATED_ATOMIC64)
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#ifdef _KERNEL
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#include <sys/kernel.h>
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struct mtx atomic_mtx;
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MTX_SYSINIT(atomic, &atomic_mtx, "atomic", MTX_DEF);
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#else
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#include <pthread.h>
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#define mtx_lock(lock) pthread_mutex_lock(lock)
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#define mtx_unlock(lock) pthread_mutex_unlock(lock)
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static pthread_mutex_t atomic_mtx;
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static __attribute__((constructor)) void
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atomic_init(void)
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{
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pthread_mutex_init(&atomic_mtx, NULL);
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}
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#endif
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void
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atomic_add_64(volatile uint64_t *target, int64_t delta)
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{
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mtx_lock(&atomic_mtx);
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*target += delta;
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mtx_unlock(&atomic_mtx);
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}
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void
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atomic_dec_64(volatile uint64_t *target)
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{
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mtx_lock(&atomic_mtx);
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*target -= 1;
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mtx_unlock(&atomic_mtx);
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}
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uint64_t
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atomic_swap_64(volatile uint64_t *a, uint64_t value)
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{
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uint64_t ret;
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mtx_lock(&atomic_mtx);
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ret = *a;
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*a = value;
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mtx_unlock(&atomic_mtx);
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return (ret);
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}
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uint64_t
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atomic_load_64(volatile uint64_t *a)
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{
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uint64_t ret;
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mtx_lock(&atomic_mtx);
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ret = *a;
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mtx_unlock(&atomic_mtx);
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return (ret);
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}
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uint64_t
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atomic_add_64_nv(volatile uint64_t *target, int64_t delta)
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{
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uint64_t newval;
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mtx_lock(&atomic_mtx);
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newval = (*target += delta);
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mtx_unlock(&atomic_mtx);
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return (newval);
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}
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uint64_t
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atomic_cas_64(volatile uint64_t *target, uint64_t cmp, uint64_t newval)
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{
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uint64_t oldval;
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mtx_lock(&atomic_mtx);
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oldval = *target;
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if (oldval == cmp)
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*target = newval;
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mtx_unlock(&atomic_mtx);
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return (oldval);
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}
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#endif
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