On Mon, Jul 2, 2018 at 7:01 PM Mathieu Desnoyers
<mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
> One thing to consider is how we will implement the load of that pointer
> on the kernel side.
Use "get_user()". It works for 64-bit objects too, and it will be
atomic in the 32-bit sub-parts on a 32-bit architecture.
Again: there is no point in trying to be atomic in the full 64 bits
(when you're running on 32-bit). The upper bits don't have to "match"
the lower bits. They just have to be zero. So doing it as two loads is
fine - the same way it's perfectly fine to do it as two stores (since
the store to the upper bits will always be zero).
Linus
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