On Tue, May 26, 2020 at 08:48:35AM -0700, Andi Kleen wrote: > On Tue, May 26, 2020 at 08:56:18AM +0200, Greg KH wrote: > > On Mon, May 25, 2020 at 10:28:48PM -0700, Andi Kleen wrote: > > > + if (val & X86_CR4_FSGSBASE) { > > > + WARN_ONCE(1, "CR4 unexpectedly set FSGSBASE!?\n"); > > > > What about those systems that panic-on-warn? > > I assume they're ok with "panic on root hole" Exactly. :) The pinning infrastructure is pretty small; will that just get backported? (Also, we can probably rework the pinning to avoid the special-casing and use a mask/value pair to notice a bit getting turned _on_ as well...) -- Kees Cook