On Wed, Jan 15, 2020 at 3:12 PM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, Jan 15, 2020 at 10:08:31AM +0100, Arnd Bergmann wrote:
>
> > > I would suggest that anybody who uses asm-generic/uaccess.h needs to
> > > simply use the generic library version.
> >
> > Or possibly just everybody altogether: the remaining architectures that
> > have a custom implementation don't seem to be doing any better either.
>
> No go for s390. There you really want to access userland memory in
> larger chunks - it's oriented for block transfers. IIRC, the insn
> they are using has a costly setup phase, independent of the amount
> to copy, followed by reasonably fast transfer more or less linear
> by the size.
Right, I missed that one while looking through the remaining
implementations.
Arnd
