On Fri, Oct 30, 2020 at 03:49:26AM +0100, Jann Horn wrote: > On Thu, Oct 29, 2020 at 2:17 PM Marco Elver <elver@xxxxxxxxxx> wrote: > > @@ -312,6 +313,9 @@ static void __do_kernel_fault(unsigned long addr, unsigned int esr, > > "Ignoring spurious kernel translation fault at virtual address %016lx\n", addr)) > > return; > > > > + if (kfence_handle_page_fault(addr)) > > + return; > > As in the X86 case, we may want to ensure that this doesn't run for > permission faults, only for non-present pages. Maybe move this down > into the third branch of the "if" block below (neither permission > fault nor NULL deref)? I think that'd make sense. Those cases *should* be mutually exclusive, but it'd be more robust to do the KFENCE checks in that last block so that if something goes wrong wrong within KFENCE we can't get stuck in a loop failing to service an instruction abort or similar. Either that, or factor out an is_el1_translation_fault() and only do the KFENCE check and is_spurious_el1_translation_fault() check under that. Thanks, Mark.
