On Mon, Jul 05, 2021 at 01:39:03PM -0700, Linus Torvalds wrote:
On Mon, Jul 5, 2021 at 1:46 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
Probably this should be
select SET_FS if CPU_HAS_ADDRESS_SPACES
Actually, I don't think m68k has a single real "set_fs()" at all, and
it should just be converted as-is to not use CONFIG_SET_FS.
Yes, there is a "set_fs()" function, but none of the remaining uses
actually are the traditional kernel style of "use kernel addresses as
user addresses". So as far as the *kernel* is concerned, m68k already
looks like a no-SET_FS architecture, and "set-fs()" is purely a
syntactic thing.
It still needs "real" kernel-style set_fs for the mm/maccess.c routines,
but adding __{get,put}_kernel_nofault should not be too hard.
So I think the right thing to do looks something like this:
- make the rule be that SFC/DFC is always normally USER_DATA
- the special m68k sequences that need to play with special segments
will always do
preempt_disable();
set_segment(..whatever segment they need..);
.. do the special operation ..
set_segment(USER_DATA);
preempt_enable();
- set_fs() goes away entirely, because the user access functions
always work on USER_DATA and SFC/DFC is always right for them.
Yes, that's what I mean with needing a more work.
