Re: [PATCH v3 45/51] x86: remove 64-byte gap at end of irq stack

From: Josh Poimboeuf
Date: Mon Aug 15 2016 - 11:42:41 EST


On Sun, Aug 14, 2016 at 12:52:40AM -0700, Andy Lutomirski wrote:
> On Fri, Aug 12, 2016 at 7:29 AM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> > There has been a 64-byte gap at the end of the irq stack for at least 12
> > years. It predates git history, and I can't find any good reason for
> > it. Remove it. What's the worst that could happen?
>
> I can't think of any reason this would matter.
>
> For that matter, do you have any idea why irq_stack_union is a union
> or why we insist on sticking it at %gs:0? Sure, the *canary* needs to
> live at a fixed offset (because GCC is daft, sigh), but I don't see
> what that has to do with the rest of the IRQ stack.

Good question. I have no idea...

--
Josh