Module Name: src
Committed By: martin
Date: Mon Jul 31 17:59:23 UTC 2023
Modified Files:
src/sys/arch/alpha/alpha [netbsd-9]: locore.s multiproc.s
Log Message:
Pull up following revision(s) (requested by riastradh in ticket #264):
sys/arch/alpha/include/asm.h: revision 1.45 (patch)
(also applied to locore.s and multiproc.s)
alpha: Add missing barriers in cpu_switchto.
Details in comments.
(accidently missed in original commit for ticket #264)
To generate a diff of this commit:
cvs rdiff -u -r1.123 -r1.123.4.1 src/sys/arch/alpha/alpha/locore.s
cvs rdiff -u -r1.13 -r1.13.92.1 src/sys/arch/alpha/alpha/multiproc.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/alpha/alpha/locore.s
diff -u src/sys/arch/alpha/alpha/locore.s:1.123 src/sys/arch/alpha/alpha/locore.s:1.123.4.1
--- src/sys/arch/alpha/alpha/locore.s:1.123 Sat Apr 6 03:06:24 2019
+++ src/sys/arch/alpha/alpha/locore.s Mon Jul 31 17:59:23 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.s,v 1.123 2019/04/06 03:06:24 thorpej Exp $ */
+/* $NetBSD: locore.s,v 1.123.4.1 2023/07/31 17:59:23 martin Exp $ */
/*-
* Copyright (c) 1999, 2000, 2019 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
#include <machine/asm.h>
-__KERNEL_RCSID(0, "$NetBSD: locore.s,v 1.123 2019/04/06 03:06:24 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locore.s,v 1.123.4.1 2023/07/31 17:59:23 martin Exp $");
#include "assym.h"
@@ -686,8 +686,28 @@ LEAF(cpu_switchto, 0)
SWITCH_CONTEXT /* swap the context */
- GET_CPUINFO
+ /*
+ * Issue barriers to coordinate mutex_exit on this CPU with
+ * mutex_vector_enter on another CPU.
+ *
+ * 1. Any prior mutex_exit by oldlwp must be visible to other
+ * CPUs before we set ci_curlwp := newlwp on this one,
+ * requiring a store-before-store barrier.
+ *
+ * 2. ci_curlwp := newlwp must be visible on all other CPUs
+ * before any subsequent mutex_exit by newlwp can even test
+ * whether there might be waiters, requiring a
+ * store-before-load barrier.
+ *
+ * See kern_mutex.c for details -- this is necessary for
+ * adaptive mutexes to detect whether the lwp is on the CPU in
+ * order to safely block without requiring atomic r/m/w in
+ * mutex_exit.
+ */
+ GET_CPUINFO /* v0 = curcpu() */
+ wmb /* store-before-store XXX patch out if !MP? */
stq s2, CPU_INFO_CURLWP(v0) /* curlwp = l */
+ mb /* store-before-load XXX patch out if !MP? */
/*
* Now running on the new PCB.
Index: src/sys/arch/alpha/alpha/multiproc.s
diff -u src/sys/arch/alpha/alpha/multiproc.s:1.13 src/sys/arch/alpha/alpha/multiproc.s:1.13.92.1
--- src/sys/arch/alpha/alpha/multiproc.s:1.13 Mon Apr 28 20:23:10 2008
+++ src/sys/arch/alpha/alpha/multiproc.s Mon Jul 31 17:59:23 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: multiproc.s,v 1.13 2008/04/28 20:23:10 martin Exp $ */
+/* $NetBSD: multiproc.s,v 1.13.92.1 2023/07/31 17:59:23 martin Exp $ */
/*-
* Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
-__KERNEL_RCSID(5, "$NetBSD: multiproc.s,v 1.13 2008/04/28 20:23:10 martin Exp $")
+__KERNEL_RCSID(5, "$NetBSD: multiproc.s,v 1.13.92.1 2023/07/31 17:59:23 martin Exp $")
/*
* Multiprocessor glue code.
@@ -65,6 +65,11 @@ NESTED_NOPROFILE(cpu_spinup_trampoline,0
/* Switch to this CPU's idle thread. */
ldq a0, CPU_INFO_IDLE_LWP(s0)
+ /*
+ * No membar needed because we're not switching from a
+ * previous lwp, and the idle lwp we're switching to can't be
+ * holding locks already; see cpu_switchto.
+ */
stq a0, CPU_INFO_CURLWP(s0) /* set curlwp */
ldq a0, L_MD_PCBPADDR(a0)
SWITCH_CONTEXT
