Re: [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context

From: Andy Lutomirski
Date: Mon Jan 05 2015 - 16:55:09 EST


On Mon, Jan 5, 2015 at 1:46 PM, Tony Luck <tony.luck@xxxxxxxxx> wrote:
> On Wed, Dec 10, 2014 at 4:24 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>> I think you need ist_begin_non_atomic() before local_irq_enable() and
>> ist_end_non_atomic() after local_irq_disable(). Otherwise it should
>> be good.
>
> In your x86/paranoid branch you added:
>
> prev_state = ist_enter(regs);
> .... body of do_machine_check() here ...
> ist_exit(regs, prev_state);
>
> Does that override the previous advice? Or do I still need something before
> I call local_irq_enable() and after local_irq_disable()?

I think I was just being vague. It would be:

prev_state = ist_enter(regs);
.... beginning of do_machine_check() here ...

if (whatever condition) {
ist_begin_non_atomic();
local_irq_enable();

...

local_irq_disable();
ist_end_non_atomic();
ist_exit(regs, prev_state);

--Andy

>
> -Tony



--
Andy Lutomirski
AMA Capital Management, LLC
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/