[PATCH] bsps/arm: More robust SMP start

[Sebastian Huber]

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