Re: [PATCH 2/2] x86/kpti: Reference all cpu_entry_area pagetables in the usermode tables

From: Thomas Gleixner
Date: Sat Dec 02 2017 - 05:38:17 EST


On Fri, 1 Dec 2017, Andy Lutomirski wrote:

> We were manually configuring cpu_entry_area in the usermode tables.
> This was error-prone and wasted memory. (Not much memory, but
> still.) Instead, just reference the same pagetables.
>
> This avoids needing to keep the KPTI code and the normal
> cpu_entry_area code in sync, since the KPTI code no longer cares
> what's in cpu_entry_area.
>
> [This does *not* work on the current KPTI series. It requires that
> all the kernelmode cpu_entry_tables are pre-allocated. That
> happens in the series as I submitted it, but tglx changed it for
> reasons that I haven't figured out.]

As I said it crashed and burned for yet unknown reasons. I'll dig into
that.

Thanks,

tglx