Re: [PATCH v4 54/57] x86/mm: convert arch_within_stack_frames() to use the new unwinder

[Kees Cook]

On Tue, Aug 23, 2016 at 5:08 PM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> On Tue, Aug 23, 2016 at 01:31:20PM -0700, Andy Lutomirski wrote:
>> On Aug 23, 2016 12:11 AM, "Linus Torvalds"
>> So the fact that this seems to have any significant effect on
>> performance suggests to me that it's being run unnecessarily
>
> Yeah, I think check_object_size() is being run unnecessarily in a lot of
> cases.  Calling it only when size is non-const would probably speed
> things up a lot.

Yup, this is at the top of my list to fix. The non-const is only done
on a handful of architectures, and it needs to be done everywhere.

-Kees

-- 
Kees Cook
Nexus Security