The noninvasive debug features of the processor are the ETM and Performance Monitoring Unit (PMU). All of these noninvasive debug features are disabled when the processor is in debug state. See System performance monitor and Chapter 14 Embedded Trace Macrocell for more information.
When the processor is in debug state:
the ETM ignores all instructions and data transfers
PMU events are not counted
events are not visible to the ETM
the PMU Cycle Count Register (CCNT) is stopped.