Re: [PATCH 03/35] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler

[Andi Kleen]

Joerg Roedel <joro@xxxxxxxxxx> writes:

> From: Joerg Roedel <jroedel@xxxxxxx>
>
> We want x86_tss.sp0 point to the entry stack later to use
> it as a trampoline stack for other kernel entry points
> besides SYSENTER.
>
> So store the task stack pointer in x86_tss.sp1, which is
> otherwise unused by the hardware, as Linux doesn't make use
> of Ring 1.

Seems like a hack. Why can't that be stored in a per cpu variable?

-Andi