fix(psci): tighten psci_power_down_wfi behaviour
A processing element should never return from a wfi, however, due to a
hardware bug, certain CPUs may wake up because of an external event.
This patch tightens the behaviour of the common power down sequence, it
ensures the routine never returns by entering a wfi loop at its end. It
aligns with the behaviour of the platform implementations.
Change-Id: I36d8b0c64eccb71035bf164b4cd658d66ed7beb4
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/lib/psci/aarch32/psci_helpers.S b/lib/psci/aarch32/psci_helpers.S
index 5cc192e..d28d469 100644
--- a/lib/psci/aarch32/psci_helpers.S
+++ b/lib/psci/aarch32/psci_helpers.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2023, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -143,6 +143,7 @@
*/
func psci_power_down_wfi
dsb sy // ensure write buffer empty
+1:
wfi
- no_ret plat_panic_handler
+ b 1b
endfunc psci_power_down_wfi
diff --git a/lib/psci/aarch64/psci_helpers.S b/lib/psci/aarch64/psci_helpers.S
index add968a..0bb1988 100644
--- a/lib/psci/aarch64/psci_helpers.S
+++ b/lib/psci/aarch64/psci_helpers.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2023, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -125,6 +125,7 @@
*/
func psci_power_down_wfi
dsb sy // ensure write buffer empty
+1:
wfi
- no_ret plat_panic_handler
+ b 1b
endfunc psci_power_down_wfi