Cortex M33 fault handlers not being executed

[David Littell]

Fault handlers that work on M4 and M7's aren't being executed on an M33.  The Usage Fault I'm creating (via an undefined instruction) appears to be escalated to a Hard Fault.  The Core stops executing instructions before ever reaching a handler.  Is this an artifact of some M33 security BS and if so, how can it be corrected?

Thanks very much for any insight.

[David Littell]

Crickets?

[pkulk.1]

Hello David, 

Did you ever get the answer on this question? I am working on similar thing right now.
we have secure project(secure boot, secure services) fault handlers and non secure (threadx, filex, etc) fault handlers.

When I used bad instruction or divide by zero it hits the secure project hard fault handler.

[David Littell · Accepted solution]

In my case the problem was the assembly handlers weren't being marked as Thumb so the Core just bailed on the handler address fetch from the Vector Table.  That little oversight in my .s file took quite a while to ferret out, ugh.

I'm sorry I don't have anything more to offer - all this security sh!t renders the (already daunting) devices *** near unusable.  Good luck.