Re: [RFCv2 00/10] Linear Address Masking enabling

Thomas Gleixner
2022-05-13T01:27:35Z

On Thu, May 12 2022 at 17:46, Dave Hansen wrote:
> On 5/12/22 17:08, H.J. Lu wrote:
> If I had to take a shot at this today, I think I'd opt for:
>
> mask = sys_enable_masking(bits=6, flags=FUZZY_NR_BITS);
>
> although I'm not super confident about the "fuzzy" flag. I also don't
> think I'd totally hate the "blind" interface where the kernel just gets
> to pick unilaterally and takes zero input from userspace.

That's the only sane choice and you can make it simple for userspace:

ret = prctl(GET_XXX_MASK, &mask);

and then let it decide based on @ret and @mask whether to use it or not.

But of course nobody thought about this as a generic feature and so we
have the ARM64 TBI muck as a precedence.

So much for coordination and portability...

I'm so tired of this short sighted 'cram my feature in' approach of
_all_ involved parties.

Thanks,

tglx