Re: [PATCHv3 0/8] Linear Address Masking enabling

Kirill A. Shutemov
2022-06-16T23:43:57Z

On Thu, Jun 16, 2022 at 10:52:14PM +0000, Edgecombe, Rick P wrote:
> On Fri, 2022-06-10 at 17:35 +0300, Kirill A. Shutemov wrote:
> > Linear Address Masking[1] (LAM) modifies the checking that is applied
> > to
> > 64-bit linear addresses, allowing software to use of the untranslated
> > address bits for metadata.
> >
> > The patchset brings support for LAM for userspace addresses.
>
> Arm has this documentation about which memory operations support being
> passed tagged pointers, and which do not:
> Documentation/arm64/tagged-address-abi.rst
>
> Is the idea that LAM would have something similar, or exactly mirror
> the arm ABI? It seems like it is the same right now. Should the docs be
> generalized?

It is somewhat similar, but not exact. ARM TBI interface implies tag size
and placement. ARM TBI is per-thread and LAM is per-process.

--
Kirill A. Shutemov