perf/core: Check kernel access when kernel callchains are requested

In the Linux kernel, the following vulnerability has been resolved: perf/core: Check kernel access when kernel callchains are requested perf_event_open() currently gates perf_allow_kernel() only on !attr.exclude_kernel. However, users can still request kernel callchain collection with attr.exclude_callchain_kernel == 0 even when attr.exclude_kernel == 1. That still requires kernel profiling privilege, but the existing check does not enforce it. Update the permission check to call perf_allow_kernel() when either kernel sampling is requested or kernel callchains are requested. This keeps permission checks aligned with requested data and prevents unprivileged use of kernel callchain capture.

Where it's fixed