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

Kirill A. Shutemov
2022-05-13T22:48:29Z

On Thu, May 12, 2022 at 08:05:26PM -0700, Dave Hansen wrote:
> On 5/12/22 18:27, Thomas Gleixner wrote:
> > 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.
>
> Well, not quite *nobody*:
>
> https://lore.kernel.org/linux-arm-kernel/7a34470c-73f0-26ac-e63d-161191d4b1e4@intel.com/

In the first RFC I tried to get ARM TBI interface generic. I resurrect it
if it fits better:

https://lore.kernel.org/all/20210205151631.43511-2-kirill.shutemov@linux.intel.com/

--
Kirill A. Shutemov