[src/trunk]: src/common/lib/libc/arch/aarch64/atomic Use the correct barriers...

[skrll <skrll%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/484e928fca5b
branches:  trunk
changeset: 955839:484e928fca5b
user:      skrll <skrll%NetBSD.org@localhost>
date:      Tue Oct 13 21:22:12 2020 +0000

description:
Use the correct barriers - all of membar_{sync,producer,consumer} have
less scope than before.

LGTM from riastradh

diffstat:

 common/lib/libc/arch/aarch64/atomic/membar_ops.S |  18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diffs (44 lines):

diff -r 47a0c43dd417 -r 484e928fca5b common/lib/libc/arch/aarch64/atomic/membar_ops.S
--- a/common/lib/libc/arch/aarch64/atomic/membar_ops.S  Tue Oct 13 21:17:35 2020 +0000
+++ b/common/lib/libc/arch/aarch64/atomic/membar_ops.S  Tue Oct 13 21:22:12 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: membar_ops.S,v 1.1 2014/08/10 05:47:35 matt Exp $ */
+/* $NetBSD: membar_ops.S,v 1.2 2020/10/13 21:22:12 skrll Exp $ */
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -32,24 +32,28 @@
 #include "atomic_op_asm.h"
 
 ENTRY_NP(_membar_producer)
-       dsb     sy
+       dmb     ishst
        ret
 END(_membar_producer)
 ATOMIC_OP_ALIAS(membar_producer,_membar_producer)
 ATOMIC_OP_ALIAS(membar_write,_membar_producer)
 STRONG_ALIAS(_membar_write,_membar_producer)
 
+ENTRY_NP(_membar_consumer)
+       dmb     ishld
+       ret
+END(_membar_producer)
+ATOMIC_OP_ALIAS(membar_consumer,_membar_consumer)
+ATOMIC_OP_ALIAS(membar_read,_membar_consumer)
+STRONG_ALIAS(_membar_read,_membar_consumer)
+
 ENTRY_NP(_membar_sync)
-       dmb     sy
+       dmb     ish
        ret
 END(_membar_sync)
 ATOMIC_OP_ALIAS(membar_sync,_membar_sync)
 ATOMIC_OP_ALIAS(membar_enter,_membar_sync)
 ATOMIC_OP_ALIAS(membar_exit,_membar_sync)
-ATOMIC_OP_ALIAS(membar_consumer,_membar_sync)
-ATOMIC_OP_ALIAS(membar_read,_membar_sync)
 STRONG_ALIAS(__sync_synchronize,_membar_sync)
 STRONG_ALIAS(_membar_enter,_membar_sync)
 STRONG_ALIAS(_membar_exit,_membar_sync)
-STRONG_ALIAS(_membar_consumer,_membar_sync)
-STRONG_ALIAS(_membar_read,_membar_sync)