With TrustZone support in armv8-m the bit-fields in EXC_RETURN have been
extended. Bit 6 ('S') now specifies whether the interrupted program was
running in the Non-Secure (S=0) or Secure (S=1) security state.
Furthermore, Bit 0 ('ES' - Exception Secure) specifies the
security state athe exception is taken to (0: Non-Secure, 1: Secure).
When NuttX is run together with TrustedFirmware-M as the application in
the non-secure world both the S and the ES bits have to be set to '0'.
For armv8-m those are also the correct values if TrustZone is not
implemented on the respective MCU or if it is disabled.
Signed-off-by: Michael Jung <mijung@gmx.net>
fbfddda28b