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

[Andy Lutomirski]

On Wed, Mar 4, 2015 at 12:39 PM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> * Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
>> On Wed, Mar 4, 2015 at 12:02 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>> >
>> > * Andy Lutomirski <luto@xxxxxxxxxxxxxx> 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?
>>
>> Hmm.  That seems a little odd to me, since we never change the TSS
>> pointer.  It's certainly better than init_tss, though.  I'll add a
>> followup to rename it.
>
> Alternatively we could use 'cpu_tss': the CPU's current TSS.

I painted my bikeshed "singleton_tss", since cpu_tss seemed redundant
for something that's already per cpu.  If you prefer your bikeshed
color, let me know.

--Andy

>
> Thanks,
>
>         Ingo



-- 
Andy Lutomirski
AMA Capital Management, LLC
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