From c8afc789196cdd568e29aa1e54cb5d24be5adf70 Mon Sep 17 00:00:00 2001 From: Achin Gupta Date: Mon, 25 Nov 2013 18:45:02 +0000 Subject: 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 --- docs/porting-guide.md | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'docs/porting-guide.md') diff --git a/docs/porting-guide.md b/docs/porting-guide.md index 0b071118..c0e6acea 100644 --- a/docs/porting-guide.md +++ b/docs/porting-guide.md @@ -188,8 +188,9 @@ the implementer chooses. In the ARM FVP port, they are implemented in bytes) of the largest cache line amongst all caches implemented in the system. A pointer to this memory should be exported with the name `platform_normal_stacks`. This pointer is used by the common platform helper - function `platform_set_stack()` to allocate a stack to each CPU in the - platform (see [../plat/common/aarch64/platform_helpers.S]). + functions `platform_set_stack()` (to allocate a stack for each CPU in the + platform) & `platform_get_stack()` (to return the base address of that + stack) (see [../plat/common/aarch64/platform_helpers.S]). 2.2 Common optional modifications @@ -262,6 +263,20 @@ The size of the stack allocated to each CPU is specified by the platform defined constant `PLATFORM_STACK_SIZE`. +### Function : platform_get_stack() + + Argument : unsigned long + Return : unsigned long + +This function uses the `platform_normal_stacks` pointer variable to return the +base address of the stack memory reserved for a CPU. Further details are given +in the description of the `platform_normal_stacks` variable below. A CPU is +identified by its `MPIDR`, which is passed as the argument. + +The size of the stack allocated to each CPU is specified by the platform defined +constant `PLATFORM_STACK_SIZE`. + + ### Function : plat_report_exception() Argument : unsigned int -- cgit