Re: remove set_fs for UML

Al Viro
2022-01-01T00:12:52Z

On Tue, Dec 21, 2021 at 10:05:03PM +0100, Richard Weinberger wrote:
> Christoph,
>
> ----- Ursprüngliche Mail -----
> > Von: "hch" <hch@lst.de>
> > An: "richard" <richard@nod.at>, "anton ivanov" <anton.ivanov@cambridgegreys.com>
> > CC: "x86" <x86@kernel.org>, "linux-um" <linux-um@lists.infradead.org>, "linux-kernel" <linux-kernel@vger.kernel.org>
> > Gesendet: Mittwoch, 15. Dezember 2021 17:56:10
> > Betreff: remove set_fs for UML
>
> > Hi Richard and Anton,
> >
> > this series removes address space overrides using set_fs for UML.
> >
> > Diffstat:
> > um/Kconfig | 1 -
> > um/include/asm/thread_info.h | 4 ----
> > um/include/asm/uaccess.h | 21 +++++++++++++++++++--
> > um/kernel/skas/uaccess.c | 25 -------------------------
> > x86/include/asm/mtrr.h | 8 +-------
> > x86/kernel/setup.c | 7 ++++++-
> > x86/um/asm/segment.h | 8 --------
> > 7 files changed, 26 insertions(+), 48 deletions(-)
>
> So far UML seems to work with these changes applied. :-)
> I have applied both patches to my UML tree for now, I assume x86 maintainers are fine with
> patch 1/2?

Hmmm... AFAICS, the right thing to do would be to have __get_kernel_nofault
and __put_kernel_nofault in arch/x86/um/asm/something. The question is how
to avoid duplicating the x86 implementation of those (along with the asm-goto
fun, etc.)...

But Christoph is right, it's not a new problem. As far as I'm concerned,
that series looks fine.