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_private.h b/common/psci/psci_private.h
index 4741397c..e2100f83 100644
--- a/common/psci/psci_private.h
+++ b/common/psci/psci_private.h
@@ -108,7 +108,7 @@ extern int get_max_afflvl(void);
 extern unsigned int psci_get_phys_state(unsigned int);
 extern unsigned int psci_get_aff_phys_state(aff_map_node *);
 extern unsigned int psci_calculate_affinity_state(aff_map_node *);
-extern unsigned int psci_get_ns_entry_info(unsigned int index);
+extern void psci_get_ns_entry_info(unsigned int index);
 extern unsigned long mpidr_set_aff_inst(unsigned long,unsigned char, int);
 extern int psci_change_state(unsigned long, int, int, unsigned int);
 extern int psci_validate_mpidr(unsigned long, int);