Module Name: src
Committed By: skrll
Date: Tue Oct 13 21:27:18 UTC 2020
Modified Files:
src/sys/arch/aarch64/aarch64: lock_stubs.S
Log Message:
Use load-acquire exclusive and store-release exclusive (and remove the
barrier instructions) as suggested by riastradh a little while ago.
To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 src/sys/arch/aarch64/aarch64/lock_stubs.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/aarch64/aarch64/lock_stubs.S
diff -u src/sys/arch/aarch64/aarch64/lock_stubs.S:1.2 src/sys/arch/aarch64/aarch64/lock_stubs.S:1.3
--- src/sys/arch/aarch64/aarch64/lock_stubs.S:1.2 Thu Aug 13 07:14:04 2020
+++ src/sys/arch/aarch64/aarch64/lock_stubs.S Tue Oct 13 21:27:18 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: lock_stubs.S,v 1.2 2020/08/13 07:14:04 skrll Exp $ */
+/* $NetBSD: lock_stubs.S,v 1.3 2020/10/13 21:27:18 skrll Exp $ */
/*-
* Copyright (c) 2014, 2020 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
#include "assym.h"
-RCSID("$NetBSD: lock_stubs.S,v 1.2 2020/08/13 07:14:04 skrll Exp $")
+RCSID("$NetBSD: lock_stubs.S,v 1.3 2020/10/13 21:27:18 skrll Exp $")
#ifndef LOCKDEBUG
/*
@@ -45,11 +45,10 @@ RCSID("$NetBSD: lock_stubs.S,v 1.2 2020/
ENTRY(mutex_enter)
mrs x1, tpidr_el1 /* x1 = curlwp */
1:
- ldxr x2, [x0] /* load old value */
+ ldaxr x2, [x0] /* load old value */
cbnz x2, 3f /* equals zero? */
stxr w3, x1, [x0] /* store curlwp as new value */
cbnz w3, 2f /* succeed? nope, try again. */
- dmb sy /* membar_enter() */
ret
2:
b 1b
@@ -64,13 +63,12 @@ END(mutex_enter)
* so just use ldxr+stxr to achieve the same.
*/
ENTRY(mutex_exit)
- dmb sy /* membar_exit() */
mrs x1, tpidr_el1 /* x1 = curlwp */
1:
ldxr x2, [x0] /* load old value */
cmp x1, x2 /* equals curlwp? */
b.ne 3f /* slow path if different */
- stxr w3, xzr, [x0] /* store zero as new value */
+ stlxr w3, xzr, [x0] /* store zero as new value */
cbnz w3, 2f /* succeed? nope, try again. */
ret
2:
