On Sun, Nov 26, 2017 at 03:55:53PM +0100, Ingo Molnar wrote: > @@ -198,6 +201,14 @@ ENTRY(entry_SYSCALL_64) > > swapgs > movq %rsp, PER_CPU_VAR(rsp_scratch) > + > + /* > + * The kernel CR3 is needed to map the process stack, but we > + * need a scratch register to be able to load CR3. %rsp is > + * clobberable right now, so use it as a scratch register. > + * %rsp will look crazy here for a couple instructions. > + */ > + SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp > movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
I think it doesn't make sense to have a SWITCH_TO_KERNEL_CR3 here. This code is the (future) kaiser-disabled path, where SWITCH_TO_KERNEL_CR3 is a no-op anyway. -- Josh
