Re: x86-64: Maintain 16-byte stack alignment

[Andy Lutomirski]

On Wed, Jan 11, 2017 at 12:09 AM, Herbert Xu
<herbert@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Jan 11, 2017 at 08:06:54AM +0000, Ard Biesheuvel wrote:
>>
>> Couldn't we update the __aligned(x) macro to emit 32 if arch == x86
>> and x == 16? All other cases should work just fine afaict
>
> Not everyone uses that macro.  You'd also need to add some checks
> to stop people from using the gcc __attribute__ directly.
>

You'd also have to audit things to make sure that __aligned__(16)
isn't being used for non-stack purposes.  After all, __aligned__(16)
in static data is fine, and it's also fine as a promise to GCC that
some object is 16-byte aligned.

--Andy