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
diff --git a/plat/common/aarch64/platform_helpers.S b/plat/common/aarch64/platform_helpers.S
index 8a6f493..770c1e2 100644
--- a/plat/common/aarch64/platform_helpers.S
+++ b/plat/common/aarch64/platform_helpers.S
@@ -35,6 +35,7 @@
.globl pcpu_dv_mem_stack
.weak platform_get_core_pos
.weak platform_set_stack
+ .weak platform_get_stack
.weak platform_is_primary_cpu
.weak platform_set_coherent_stack
.weak platform_check_mpidr
@@ -95,19 +96,28 @@
cset x0, eq
ret
-
/* -----------------------------------------------------
- * void platform_set_stack (int mpidr)
+ * void platform_get_stack (unsigned long mpidr)
* -----------------------------------------------------
*/
-platform_set_stack:; .type platform_set_stack, %function
- mov x9, x30 // lr
+platform_get_stack:; .type platform_get_stack, %function
+ mov x10, x30 // lr
bl platform_get_core_pos
add x0, x0, #1
mov x1, #PLATFORM_STACK_SIZE
mul x0, x0, x1
ldr x1, =platform_normal_stacks
- add sp, x1, x0
+ add x0, x1, x0
+ ret x10
+
+ /* -----------------------------------------------------
+ * void platform_set_stack (unsigned long mpidr)
+ * -----------------------------------------------------
+ */
+platform_set_stack:; .type platform_set_stack, %function
+ mov x9, x30 // lr
+ bl platform_get_stack
+ mov sp, x0
ret x9
/* -----------------------------------------------------