Linux 5.1 Landing Feature For Reducing Scope Of Spectre V4 Speculation Protection

The x86/pti updates for Linux 5.1 is bringing a new PR_SPEC_DISABLE_NOEXEC option where speculation protection for SSBD doesn't end up being passed to new processes started by exec in such use-cases where it's safe to do so. Utilizing this option will thus eliminate the overhead associated with this Spectre Variant 4 "Speculative Store Bypass" behavior...