On Sun, Nov 20, 2016 at 11:13 PM, Ingo Molnar <mi...@kernel.org> wrote:
>
> So I have applied your fix that addresses the worst fallout directly:
>
> fc0e81b2bea0 x86/traps: Ignore high word of regs->cs in
> early_fixup_exception()
>
> ... but otherwise we might be better off zeroing out the high bits of segment
> registers stored on the stack, in all entry code pathways
Ugh.
I'd much rather we go back to just making the "cs" entry explicitly
16-bit, and have a separate padding entry, the way we used to long
long ago.
Or just rename it to something that you're not supposed to access
directly, and a helper accessor function that masks off the high bits.
The entry code-paths are *much* more critical than any of the few user
codepaths. Let's not add complexity to entry. Make the structure
actually reflect reality instead.
Linus
