AnsweredAssumed Answered

LPC55S69 : call nonsecure function from secure ISR

Question asked by Eugene Hiihtaja on Nov 15, 2019
Latest reply on Nov 19, 2019 by Sabina Bruce

Hi !


I would like to handle interrupt on secure side.

When interrupt occurs, I should be able to call function on nonsecure side ( from Isecure SR context ) and it will send message to FreeRTOS task.

If interrupt handled on nonsecure side, it is not a problem to send message to RTOS becouse it run on nonsecure side also.


I have check all SDK examples and always all calls from nonsecure to secure side.


But how to compose this call :


• BXLNS: Branch with Link Exchange Non Secure - calls a subroutine in NS memory.
On executing either the BXNS or BXLNS instructions the CPU-S will also change to the
Non-secure state (CPU-NS) and thus be in the correct state for executing out of NS


How  secure side can know where known function located on nonsecure side ?

If secure side in ISR context , does nonsecure will look as in ISR context and I should use freertos function for ISR context ?