It seems to be userspace accessible: https://developer.apple.com/documentation/xcode/writing-arm6...

The kernel would have to be aware of it in order to be able to restore its state across context switches though, unless it's part of a set of registers that is automatically persisted. But given that Apple is publicly documenting this flag, I suppose it is.

Here's an interesting conversation by the Go developers from as early as 2021 being suspicious of DIT: https://github.com/golang/go/issues/49702