Re: [RFC 1/4] asm-generic/uaccess: don't define inline functions if noinline lib/* in use

[Al Viro]

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.