[PATCH] aarch64: MTE compatible strchrnul

[Florian Weimer]

* Andrea Corallo:

> Florian Weimer <fweimer@redhat.com> writes:
>
>> * Andrea Corallo:
>>
>>> Introduce an Arm MTE compatible strchrnul implementation.
>>>
>>> Benchmarked on Cortex-A72, Cortex-A53, Neoverse N1 does not show
>>> performance regressions.
>>>
>>> Co-authored-by: Wilco Dijkstra <wilco.dijkstra@arm.com>
>>
>> As a very high-level comment, I would expect some sort of markup in the
>> file that this implementation is now MTE-safe, similar to what we have
>> for executable stacks.
>>
>> Or do you plan to handle that in some other fashion?
>>
>> Thanks,
>> Florian
>
> Hi Florian,
>
> Now the only markup is the comment on the top of the file stating the
> MTE compatibility of the routine.
>
> I'm not aware of how this marking is done for executable stacks, perhaps
> could you give an hook on where to look for?

Typically, the -z noexecstack flag or a special .note.GNU-stack section
is used for that.

> Just to make sure we are one the same page wanted to add: these
> functions are supposed to be backward compatible with what they are
> replacing, so I'm not sure a marking is necessary.

It's MTE that isn't backwards-compatible without such markup.

Thanks,
Florian