# Re: \[PATCH v11 21/39\] arm64/gcs: Ensure that new threads have a GCS

- From: Mark Brown \<broonie@kernel.org\>
- Date: 2024-08-22 16:24:40 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2024/08/289775
- Thread: https://ratatoskr.run/linux-arm-kernel/2024/08/289561/t.md

```text
On Thu, Aug 22, 2024 at 05:17:14PM +0100, Catalin Marinas wrote:

> >  	/*
> > -	 * Ensure that GCS changes are observable by/from other PEs in
> > -	 * case of migration.
> > +	 * Ensure that GCS memory effects of the 'prev' thread are
> > +	 * ordered before other memory accesses with release semantics
> > +	 * (or preceded by a DMB) on the current PE. In addition, any
> > +	 * memory accesses with acquire semantics (or succeeded by a
> > +	 * DMB) are ordered before GCS memory effects of the 'next'
> > +	 * thread. This will ensure that the GCS memory effects are
> > +	 * visible to other PEs in case of migration.
> >  	 */
> > -	gcsb_dsync();
> > +	if (task_gcs_el0_enabled(current) || task_gcs_el0_enabled(next))
> > +		gcsb_dsync();

> Ah, the comment turned up in this patch. It looks fine.

Oh, sorry - I should probably just pull this hunk into the other patch.
```

## Attachments

- [signature.asc](https://ratatoskr.run/linux-arm-kernel/2024/08/289775/attachment/0) (application/pgp-signature, 488 bytes)