/* $NetBSD: membar_ops.S,v 1.13 2022/04/21 12:06:31 riastradh Exp $ */
/*-
* Copyright (c) 2006, 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe, and by Andrew Doran.
*
* 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 "atomic_op_asm.h"
.text
.set noreorder
LEAF(_membar_sync)
j ra
BDSYNC
END(_membar_sync)
ATOMIC_OP_ALIAS(membar_sync,_membar_sync)
STRONG_ALIAS(_membar_enter,_membar_sync)
ATOMIC_OP_ALIAS(membar_enter,_membar_sync)
#ifdef __OCTEON__
/*
* cnMIPS guarantees load-before-load/store ordering without any
* barriers. So the only barriers we need are store-before-load (sync)
* and store-before-store (syncw, i.e., sync 4). See Table 2-32
* `Execution Ordering Rules' on p. 104 of Cavium OCTEON III CN78XX
* Hardware Reference Manual, CN78XX-HM-0.99E, September 2014:
*
* First Operation DLD [load instruction to a physical
* address that is L2/DRAM]
* Second Operation Any
* Execution Ordering Comments
*
* The second operation cannot appear to execute before
* the first (DLD) operation, regardless of the presence
* or absence of SYNC* instructions.
*
* Note: I'm not sure if this applies to earlier cnMIPS -- can't find
* it in the Cavium Networks OCTEON Plus CN50XX Hardware Reference
* Manual CN50XX-HM-0.99E, July 2008. Experimentally, on an erlite3
* (Cavium Octeon CN5020-500), I can easily detect reordering of
* store-before-store and store-before-load, but I haven't been able to
* detect any reordering of load-before-load or load-before-store.
*
* Note: On early cnMIPS (CN3xxx), there is an erratum which sometimes
* requires issuing two syncw's in a row. I don't know the details --
* don't have documentation -- and in Linux it is only used for I/O
* purposes.
*
* Currently we don't build kernels that work on both Octeon and
* non-Octeon MIPS CPUs, so none of this is done with binary patching.
* For userlands we could use a separate shared library on Octeon with
* ld.so.conf to override the symbols with cheaper definitions, but we
* don't do that now.
*/
LEAF(_membar_acquire)
j ra
nop
END(_membar_acquire)
ATOMIC_OP_ALIAS(membar_acquire,_membar_acquire)
STRONG_ALIAS(_membar_consumer,_membar_acquire)
ATOMIC_OP_ALIAS(membar_consumer,_membar_acquire)
LEAF(_membar_release)
j ra
syncw
END(_membar_release)
ATOMIC_OP_ALIAS(membar_release,_membar_release)
STRONG_ALIAS(_membar_exit,_membar_release)
ATOMIC_OP_ALIAS(membar_exit,_membar_release)
STRONG_ALIAS(_membar_producer,_membar_release)
ATOMIC_OP_ALIAS(membar_producer,_membar_release)
#else /* !__OCTEON__ */
STRONG_ALIAS(_membar_acquire,_membar_sync)
ATOMIC_OP_ALIAS(membar_acquire,_membar_sync)
STRONG_ALIAS(_membar_release,_membar_sync)
ATOMIC_OP_ALIAS(membar_release,_membar_sync)
STRONG_ALIAS(_membar_exit,_membar_sync)
ATOMIC_OP_ALIAS(membar_exit,_membar_sync)
STRONG_ALIAS(_membar_consumer,_membar_sync)
ATOMIC_OP_ALIAS(membar_consumer,_membar_sync)
STRONG_ALIAS(_membar_producer,_membar_sync)
ATOMIC_OP_ALIAS(membar_producer,_membar_sync)
#endif