Take advantage of the fact that the WFI instruction does continue

immediately if there is a pending interrupt to fix a potential race
in the idle loop.

ok guenther@

diff --git a/sys/arch/arm64/arm64/machdep.c b/sys/arch/arm64/arm64/machdep.c
index 6b2dcba..d0c1601 100644 (file)
--- a/sys/arch/arm64/arm64/machdep.c
+++ b/sys/arch/arm64/arm64/machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: machdep.c,v 1.83 2023/07/13 08:33:36 kettenis Exp $ */
+/* $OpenBSD: machdep.c,v 1.84 2023/08/10 21:01:50 kettenis Exp $ */
 /*
  * Copyright (c) 2014 Patrick Wildt <patrick@blueri.se>
  * Copyright (c) 2021 Mark Kettenis <kettenis@openbsd.org>
@@ -209,6 +209,7 @@ consinit(void)
 void
 cpu_idle_enter(void)
 {
+       disable_irq_daif();
 }
 
 void (*cpu_idle_cycle_fcn)(void) = cpu_wfi;
@@ -216,13 +217,15 @@ void (*cpu_idle_cycle_fcn)(void) = cpu_wfi;
 void
 cpu_idle_cycle(void)
 {
-       enable_irq_daif();
        cpu_idle_cycle_fcn();
+       enable_irq_daif();
+       disable_irq_daif();
 }
 
 void
 cpu_idle_leave(void)
 {
+       enable_irq_daif();
 }
 
 /* Dummy trapframe for proc0. */