Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*

H. Peter Anvin
2014-04-29T03:47:35Z

On 04/28/2014 08:45 PM, H. Peter Anvin wrote:
>
> OK, so I found a bug in ldttest.c -- it sets CS to an LDT segment, but
> it never sets SS to an LDT segment. This means that it should really
> have zero footprint versus the espfix code, and implies that we instead
> have another bug involved. Why the espfix code should have any effect
> whatsoever is a mystery, however... if it indeed does?
>
> I have uploaded a fixed ldttest.c, but it seems we might be chasing more
> than that...
>

In particular, I was already wondered how we avoid an "upside down
swapgs" with a #GP on IRET. The answer might be that we don't...

-hpa