[PATCH v1 4/4] arm64/mte: Add userspace interface for enabling asymmetric mode

[Mark Brown]

On Wed, Mar 02, 2022 at 11:44:53AM +0000, Catalin Marinas wrote:
> On Tue, Mar 01, 2022 at 04:52:01PM -0800, Evgenii Stepanov wrote:

> > Extending PR_MTE_TCF_MASK seems bad for backward compatibility. User
> > code may do "flags =& ~PR_MTE_TCF_MASK" to disable MTE; when compiled
> > against an old version of the header this would fail to remove the ASYMM
> > bit.

> But if the app is compiled against an old version, it wouldn't set
> MTE_CTRL_TCF_ASYMM either as it doesn't have the definition.

Indeed - and any attempt to set MTE_CTRL_TCF_ASYMM (or any other bit
without a specified meaning) on a system without this support results in
an error so it's hard to see how older code could have mistakenly
enabled it.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20220302/78cff995/attachment.sig>