On Mon, Jul 13, 2020 at 03:19:42PM +0200, Geert Uytterhoeven wrote: > > This used to set KERNEL_DS, and now it sets USER_DS, which looks wrong > > superficially. > > Thanks for noticing, and sorry for missing that myself. > > The same issue is present for SuperH: > > - set_fs(KERNEL_DS); > + oldfs = force_uaccess_begin(); > > So the patch description should be: > > "Add helpers to wraper the get_fs/set_fs magic for undoing any damage > done by set_fs(USER_DS)." > > and leave alone users setting KERNEL_DS? Yes, this was broken. Fixed for the next version. > > If the new behaviour is fine it suggests that the old behaviour was > > wrong, or that this is superfluous and could go entirely. > > > > Geert? > > Nope, on m68k, TLB cache operations operate on the current address space. > Hence to flush a kernel TLB entry, you have to switch to KERNEL_DS first. > > If we're guaranteed to be already using KERNEL_DS, I guess the > address space handling can be removed. But can we be sure? We can't be sure yet. But with a lot of my pending work we should be able to get there in the not too far future.
