SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
The Cortex-M4F has two modes of operation:
Used to execute application software. The processor enters thread mode when it comes out of reset.
Used to handle exceptions. When the processor has finished exception processing, it returns to thread mode.
The Cortex-M4F also has two privilege levels:
In this mode, software has the following restrictions:
In this mode, software can use all the instructions and has access to all resources.
In thread mode, the CONTROL register (see Figure 1-12) 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.