UBUNTU-CVE-2026-97499: Low severity ubuntu/linux vulnerability

In the Linux kernel, the following vulnerability has been resolved: coresight: perf: Retrieve path and source from event data ETM perf callbacks currently use the per-CPU csdevsrc pointer, which can race with updates during device registration and unregistration. The AUX setup already builds and stores the path in the event data. Use this path to retrieve the source instead of csdevsrc to avoid the race. Export coresightgetsource() and add etmeventgetctxtpath() to retrieve the context's path and its source with READONCE() / WRITEONCE() accessors. Give the comments to explain why this approach is safe when pause or resume callbacks preempt the disable callback (e.g. via NMI).