psci: fix error due to a non zero context id

In the previous psci implementation, the psci_afflvl_power_on_finish()
function would run into an error condition if the value of the context
id parameter in the cpu_on and cpu_suspend psci calls was != 0. The
parameter was being restored as the return value of the affinity level
0 finisher function. A non zero context id would be treated as an
error condition. This would prevent successful wake up of the cpu from
a power down state. Also, the contents of the general purpose
registers were not being cleared upon return to the non-secure world
after a cpu power up. This could potentially allow the non-secure
world to view secure data.

This patch ensures that all general purpose registers are set to ~0
prior to the final eret that drops the execution to the non-secure
world. The context id is used to initialize the general purpose
register x0 prior to re-entry into the non-secure world and is no
longer restored as a function return value. A platform helper
(platform_get_stack()) has been introduced to facilitate this change.

Change-Id: I2454911ffd75705d6aa8609a5d250d9b26fa097c

1 files changed, 1 insertions, 1 deletions

diff --git a/common/psci/psci_afflvl_suspend.c b/common/psci/psci_afflvl_suspend.c
index b68b4df7..05b0aad0 100644
--- a/common/psci/psci_afflvl_suspend.c
+++ b/common/psci/psci_afflvl_suspend.c
@@ -389,7 +389,7 @@ static unsigned int psci_afflvl0_suspend_finish(unsigned long mpidr,
 	 * information that we had stashed away during the suspend
 	 * call to set this cpu on it's way.
 	 */
-	rc = psci_get_ns_entry_info(index);
+	psci_get_ns_entry_info(index);
 
 	/* Clean caches before re-entering normal world */
 	dcsw_op_louis(DCCSW);