Re: [PATCH] x86: entry_32.S: change ESPFIX test to not touch PT_OLDSS(%esp)

[H. Peter Anvin]

On 03/09/2015 09:44 AM, Linus Torvalds wrote:
> 
> And remember: those zero-cost out-of-order branches turn quite
> expensive if they *ever* mispredict. Even a 5% mispredict rate is
> likely to mean "it's better to have a data dependency chain".
> 
> So it could easily go either way. I'm not convinced the old code is bad at all.
> 

I'm inclined to side with Linus here.  I'm hesitant to change this based
on pure speculation.

To answer Andy's question: I do believe we need espfix for V86 mode as well.

	-hpa


--
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/