__ARM_FEATURE_CMSE
In this section:
Description
An integer that is set based on the compiler options ‑‑cpu and ‑‑cmse. The symbol is set to 3 if the selected processor architecture has CMSE (Cortex-M security extensions) and the compiler option ‑‑cmse is specified.
The symbol is set to 1 if the selected processor architecture has CMSE and the compiler option ‑‑cmse is not specified.
The symbol is undefined for cores without CMSE.