Re: [RFC 1/3] x86: Add this_cpu_sp0() to read sp0 for the current cpu

[Ingo Molnar <mingo@kernel.org>]

* Andy Lutomirski <luto@amacapital.net> wrote:

> We currently store references to the top of the kernel stack in 
> multiple places: kernel_stack (with an offset) and 
> init_tss.x86_tss.sp0 (no offset).  The latter is defined by hardware 
> and is a clean canonical way to find the top of the stack.  Add an

Btw., 'per_cpu(init_tss)' is a somewhat misleading name these days, as 
there's nothing 'init' about it anymore - we load it during CPU init 
and then manually maintain its contents. A better name would be 
'current_tss' - referring to both the current CPU and the current 
task?

> This needs minor paravirt tweaks to ensure that On native, sp0

nit: s/On/on/

> defines the top of the kernel stack.  On Xen and lguest, the 
> hypervisor tracks it, but we want to start reading sp0 in the 
> kernel.  Fixing this is simple: just update our local copy of sp0 as 
> well as the hypervisor's copy on task switches.

Thanks,

	Ingo