Linux 6.15 Lands Patches To Further Clean Up Its Spectre RSB Mitigations

Merged today was this week's batch of x86 fixes ahead of the Linux 6.15-rc2 release on Sunday. Notable with these x86 fixes are landing several patches to fix and clean-up the Spectre Return Stack Buffer "RSB" mitigation handling as well as introducing a new document to clarify the overall state and current mitigations...