[PATCH v3 4/5] cpukit: Add signal mapping support

[Kinsey Moore]

On 10/28/2021 01:02, Sebastian Huber wrote:
> On 27/10/2021 23:44, Kinsey Moore wrote:
>> +/*
>> + * Exception handler. Map the exception class to SIGFPE, SIGSEGV
>> + * or SIGILL for Ada or other runtimes.
>> + */
>> +void _Exception_Raise_signal(
>> +  Internal_errors_Source source,
>> +  bool                   always_set_to_false,
>> +  Internal_errors_t      code
>> +)
>> +{
>> +  CPU_Exception_frame *ef;
>> +  int raise_signal;
>> +
>> +  if ( source != RTEMS_FATAL_SOURCE_EXCEPTION ) {
>> +    return;
>> +  }
>> +
>> +  ef = (rtems_exception_frame *) code;
>> +  raise_signal = _CPU_Exception_frame_get_signal( ef );
>> +  if ( raise_signal < 0 ) {
>> +    return;
>> +  }
>> +
>> +  /* Disable thread dispatch */
>> +  _CPU_Exception_disable_thread_dispatch();
>> +
>> +  /*
>> +   * While it would be preferable, the call to raise() cannot be 
>> deferred to a
>> +   * post-switch action because it attempts to lock the post-switch 
>> action list
>> +   * to add another item and the list is already locked for 
>> iteration. This
>> +   * causes a deadlock.
>> +   */
>> +  raise( raise_signal );
>
> When you get an early exception (before RTEMS is initialized), then 
> you get a double exception here or some sort of undefined behaviour.
>
I can use the system state for non-SMP systems and the Per_CPU state for 
SMP systems to ensure the current CPU is up for multitasking to prevent 
this functionality from executing in the case of an early exception. I 
find it a little odd that those are mutually exclusive (Per_CPU state 
isn't updated on non-SMP systems and overall system state isn't relevant 
for this on SMP systems).


Kinsey