[PATCH v1 1/2] score: Enforce stack_end alignment

[Sebastian Huber]

Hello Kinsey,

I think the root cause is that this is not necessarily stack aligned:

On 01/03/2021 23:59, Kinsey Moore wrote:
> thread_config->stack_area = _Stack_Allocate( size );

Also this (easy to fix):

/**
  * @ingroup RTEMSAPIClassicTasks
  *
  * @brief This constant defines the recommended alignment of a task storage
  *   area in bytes.
  *
  * @par Notes
  * Use it with RTEMS_ALIGNED() to define the alignment of a statically
  * allocated task storage area.
  */
#define RTEMS_TASK_STORAGE_ALIGNMENT CPU_HEAP_ALIGNMENT

We have currently only heap alignment. I think we have to account for a 
potential stack alignment in the allocation size and the task storage 
components:

/**
  *  @brief Size of floating point context area.
  *
  *  This constant defines the number of bytes required
  *  to store a full floating point context.
  */
#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
   #define CONTEXT_FP_SIZE \
     ( ( CPU_CONTEXT_FP_SIZE + CPU_HEAP_ALIGNMENT - 1 ) \
       & ~( CPU_HEAP_ALIGNMENT - 1 ) )
#else
   #define CONTEXT_FP_SIZE 0
#endif

uintptr_t _TLS_Get_allocation_size( void )
{
   uintptr_t size;
   uintptr_t allocation_size;
   uintptr_t alignment;

   size = _TLS_Get_size();

   if ( size == 0 ) {
     return 0;
   }

   allocation_size = _TLS_Allocation_size;

   if ( allocation_size == 0 ) {
     allocation_size = _TLS_Heap_align_up( size );
     alignment = _TLS_Heap_align_up( (uintptr_t) _TLS_Alignment );

     /*
      * The stack allocator does not support aligned allocations. Allocate
      * enough to do the alignment manually.
      */
     if ( alignment > CPU_HEAP_ALIGNMENT ) {
       allocation_size += alignment;
     }

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