Re: [lkp-robot] [x86/kconfig] 81d3871900: BUG:unable_to_handle_kernel

[Andy Lutomirski]

On Fri, Oct 13, 2017 at 12:09 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, Oct 13, 2017 at 6:56 AM, Andrey Ryabinin
> <aryabinin@xxxxxxxxxxxxx> wrote:
>>
>> This could be fixed by s/vmovdqa/vmovdqu change like bellow, but maybe the right fix
>> would be to align the data properly?
>
> I suspect anything that has the SHA extensions should also do
> unaligned loads efficiently. The whole "aligned only" model is broken.
> It's just doing two loads from the state pointer, there's likely no
> point in trying to align it.
>
> So your patch looks fine, but maybe somebody could add the required
> alignment to the sha256 context allocation (which I don't know where
> it is).

IIRC if we try the latter, then we'll risk hitting the #*!&@% gcc bug
that mostly prevents 16-byte alignment from working on GCC before 4.8
or so.  That way lies debugging disasters.