[PATCH] bsps/arm: More robust SMP start

[Gedare Bloom]

seems fine to me

On Wed, Aug 4, 2021 at 6:41 AM Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
>
> Do not continue execution on processors which are not configured to prevent the
> use of arbitrary memory for the initialization stack.
> ---
>  bsps/arm/fvp/start/bspstarthooks.c             |  5 +----
>  bsps/arm/realview-pbx-a9/start/bspstarthooks.c |  6 +-----
>  bsps/arm/shared/start/start.S                  | 16 ++++++++++++++--
>  3 files changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/bsps/arm/fvp/start/bspstarthooks.c b/bsps/arm/fvp/start/bspstarthooks.c
> index f0087efa06..d5e56423f4 100644
> --- a/bsps/arm/fvp/start/bspstarthooks.c
> +++ b/bsps/arm/fvp/start/bspstarthooks.c
> @@ -66,10 +66,7 @@ void bsp_start_hook_0( void )
>       * Prevent the fatal errors SMP_FATAL_MULTITASKING_START_ON_INVALID_PROCESSOR
>       * and SMP_FATAL_MULTITASKING_START_ON_UNASSIGNED_PROCESSOR this way.
>       */
> -    if (
> -      cpu_index_self >= rtems_configuration_get_maximum_processors()
> -        || !_SMP_Should_start_processor( cpu_index_self )
> -    ) {
> +    if ( !_SMP_Should_start_processor( cpu_index_self ) ) {
>        while ( true ) {
>          _ARM_Wait_for_event();
>        }
> diff --git a/bsps/arm/realview-pbx-a9/start/bspstarthooks.c b/bsps/arm/realview-pbx-a9/start/bspstarthooks.c
> index 1e386bfd23..9549e7235c 100644
> --- a/bsps/arm/realview-pbx-a9/start/bspstarthooks.c
> +++ b/bsps/arm/realview-pbx-a9/start/bspstarthooks.c
> @@ -67,11 +67,7 @@ BSP_START_TEXT_SECTION void bsp_start_hook_0(void)
>     * the fatal errors SMP_FATAL_MULTITASKING_START_ON_INVALID_PROCESSOR and
>     * SMP_FATAL_MULTITASKING_START_ON_UNASSIGNED_PROCESSOR this way.
>     */
> -  if (
> -    cpu_index_self != 0 &&
> -      (cpu_index_self >= rtems_configuration_get_maximum_processors() ||
> -        !_SMP_Should_start_processor(cpu_index_self))
> -  ) {
> +  if (cpu_index_self != 0 && !_SMP_Should_start_processor(cpu_index_self)) {
>      while (true) {
>        _ARM_Wait_for_event();
>      }
> diff --git a/bsps/arm/shared/start/start.S b/bsps/arm/shared/start/start.S
> index bc87e7b36d..55b5b8d78c 100644
> --- a/bsps/arm/shared/start/start.S
> +++ b/bsps/arm/shared/start/start.S
> @@ -197,9 +197,21 @@ _start:
>         /* Read MPIDR and get current processor index */
>         mrc     p15, 0, r7, c0, c0, 5
>         and     r7, #0xff
> -#endif
>
> -#ifdef RTEMS_SMP
> +       /*
> +        * Check that this is a configured processor.  If not, then there is
> +        * not much what can be done since we do not have a stack available for
> +        * this processor.  Just loop forever in this case.
> +        */
> +       ldr     r1, =_SMP_Processor_configured_maximum
> +       ldr     r1, [r1]
> +       cmp     r1, r7
> +       bgt     .Lconfigured_processor
> +.Linvalid_processor_wait_for_ever:
> +       wfe
> +       b       .Linvalid_processor_wait_for_ever
> +.Lconfigured_processor:
> +
>          /*
>           * Get current per-CPU control and store it in PL1 only Thread ID
>           * Register (TPIDRPRW).
> --
> 2.26.2
>
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