SWCU191 February 2022 CC1311P3 , CC1311R3 , CC2651P3 , CC2651R3 , CC2651R3SIPA
The Arm® Cortex®-M4 processor has two modes of operation:
In addition, the Arm® Cortex®-M4 processor has two privilege levels, unprivileged and privileged.
In thread mode, the CONTROL register (see Table 3-24) controls whether software execution is privileged or unprivileged. In handler mode, software execution is always privileged.
Only privileged software can write to the CONTROL register to change the privilege level for software execution in thread mode. Unprivileged software can use the SVC instruction to make a supervisor call to transfer control to privileged software.