minix/common/lib/libc/arch/sparc/atomic/atomic_cas.S

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/* $NetBSD: atomic_cas.S,v 1.11 2011/02/22 18:45:10 pooka Exp $ */
/*-
* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Andrew Doran and Jason R. Thorpe.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#include <sys/param.h>
#include "atomic_op_asm.h"
#if defined(_HARDKERNEL)
#include <machine/psl.h>
#include "opt_multiprocessor.h"
#define DISABLE_INTERRUPTS \
rd %psr, %o4 /* disable interrupts */;\
or %o4, PSR_PIL, %o5 ;\
wr %o5, 0, %psr ;\
nop ;\
nop ;\
nop
#define RESTORE_INTERRUPTS \
wr %o4, 0, %psr /* enable interrupts */ ;\
nop ;\
nop ;\
nop
#else /* _HARDKERNEL */
#define MULTIPROCESSOR 1
#define DISABLE_INTERRUPTS /* nothing */
#define RESTORE_INTERRUPTS /* nothing */
#endif /* _HARDKERNEL */
#if defined(MULTIPROCESSOR)
.section .bss
.align 1024
#ifdef PIC
.globl _C_LABEL(_atomic_cas_locktab)
#endif
OTYPE(_C_LABEL(_atomic_cas_locktab))
_C_LABEL(_atomic_cas_locktab):
.space 1024
#ifdef PIC
/* o4 is not used for PSR in PIC cases, so we can use it here */
#define GETLOCKTAB \
PIC_PROLOGUE(%o3,%o4) ;\
set _C_LABEL(_atomic_cas_locktab), %o4 ;\
ld [%o3 + %o4], %o3
#else
#define GETLOCKTAB \
sethi %hi(_C_LABEL(_atomic_cas_locktab)), %o3
#endif
#define ACQUIRE_INTERLOCK \
DISABLE_INTERRUPTS ;\
srl %o0, 3, %o5 /* get lock address */ ;\
and %o5, 1023, %o5 ;\
GETLOCKTAB ;\
add %o5, %o3, %o5 ;\
;\
/* %o5 has interlock address */ ;\
;\
1: ldstub [%o5], %o3 /* acquire lock */ ;\
tst %o3 ;\
bz,a 2f ;\
nop ;\
nop ;\
nop ;\
b,a 1b /* spin */ ;\
nop ;\
/* We now hold the interlock */ ;\
2:
#define RELEASE_INTERLOCK \
stb %g0, [%o5] /* release interlock */ ;\
RESTORE_INTERRUPTS
#else /* ! MULTIPROCESSOR */
#define ACQUIRE_INTERLOCK DISABLE_INTERRUPTS
#define RELEASE_INTERLOCK RESTORE_INTERRUPTS
#endif /* MULTIPROCESSOR */
.text
/*
* The v7 and v8 SPARC doesn't have compare-and-swap, so we block interrupts
* and use an interlock.
*
* XXX On single CPU systems, this should use a restartable sequence:
* XXX there we don't need the overhead of interlocking.
*
* XXX NOTE! The interlock trick only works if EVERYTHING writes to
* XXX the memory cell through this code path!
*/
ENTRY(_atomic_cas_32)
ACQUIRE_INTERLOCK
! %o4 has saved PSR value
! %o5 has interlock address
ld [%o0], %o3 ! get old value
cmp %o1, %o3 ! old == new?
beq,a 3f ! yes, do the store
st %o2, [%o0] ! (in the delay slot)
3: RELEASE_INTERLOCK
retl
mov %o3, %o0 ! return old value
ATOMIC_OP_ALIAS(atomic_cas_32,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_uint,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_uint,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_ulong,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_ulong,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_ptr,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_ptr,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_32_ni,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_32_ni,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_uint_ni,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_uint_ni,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_ulong_ni,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_ulong_ni,_atomic_cas_32)
ATOMIC_OP_ALIAS(atomic_cas_ptr_ni,_atomic_cas_32)
STRONG_ALIAS(_atomic_cas_ptr_ni,_atomic_cas_32)