Re: Broken check rejecting -fcf-protection and -mindirect-branch=thunk-extern

[Andy Lutomirski]

> On Apr 28, 2020, at 9:14 AM, Peter Zijlstra <pet...@infradead.org> wrote:
> 
> On Tue, Apr 28, 2020 at 02:41:33PM +0100, Andrew Cooper wrote:
>> Its fine to focus on userspace first, but the kernel is far more simple.
>> 
>> Looking at that presentation, the only thing missing for kernel is the
>> notrack thunks, in the unlikely case that such code would be tolerated
>> (Frankly, I don't expect Xen or Linux to run with notrack enabled, as
>> there is no legacy code to be concerned with).
> 
> Uhhh.. ftrace and kretprobes play dodgy games with the
> return stack, doesn't that make the CET thing slightly more interesting?

It’s definitely interesting. But there isn’t legacy code involved — we can 
recompile and fix the world :)