Re: [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator

[Kees Cook]

On September 19, 2023 9:02:07 AM PDT, Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>On 9/19/23 08:48, Matteo Rizzo wrote:
>>> I think the whole "make it one single compile-time option" model is
>>> completely and fundamentally broken.
>> Wouldn't making this toggleable at boot time or runtime make performance
>> even worse?
>
>Maybe.
>
>But you can tolerate even more of a performance impact from a feature if
>the people that don't care can actually disable it.
>
>There are also plenty of ways to minimize the overhead of switching it
>on and off at runtime.  Static branches are your best friend here.

Let's start with a boot time on/off toggle (no per-slab, no switch on out-of-space, etc). That should be sufficient for initial ease of use for testing, etc. But yes, using static_branch will nicely DTRT here.



-- 
Kees Cook