Re: [RFC PATCH for 4.18] rseq: use __u64 for rseq_cs fields, validate user inputs

[Linus Torvalds]

On Mon, Jul 2, 2018 at 7:30 PM Mathieu Desnoyers
<mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
>
> Is it really ? Last time we had this discussion, not all architectures
> guaranteed that reading a 64-bit integer would happen in two atomic
> 32-bit sub-parts.

All architectures that matter do.

Please don't overdesign this, or try to make a problem out of
something that isn't a problem.

Sure, maybe some toy architecture does a 8-byte "get_user()" as a
"copy_from_user()" one byte at a time, because that's the best way to
do unaligned accesses.

But nobody will ever care about rseq on such a thing anyway. Let it go.

               Linus