On Fri, Apr 03, 2020 at 02:37:19PM +0100, Russell King - ARM Linux admin wrote: > > I think uaccess_enable() could indeed switch the kernel domain if > > KERNEL_DS is set and move this out of set_fs(). It would reduce the > > window the kernel domain permissions are overridden. Anyway, > > uaccess_enable() appeared much later on arm when Russell introduced PAN > > (SMAP) like support by switching the user domain. > > Yes, that would be a possibility. Another possibility would be to > eliminate as much usage of KERNEL_DS as possible That's definitely worth doing, but that's another long-term project ;-/ > - I've just found > one instance in sys_oabi-compat.c that can be eliminated (epoll_ctl) > but there's several there that can't with the current code structure, > and re-coding the contents of some fs/* functions to work around that > is a very bad idea. If there's some scope for rejigging some of the > fs/* code, it may be possible to elimate some other cases in there. Well, your do_locks() definitely can be converted. epoll_wait()... not sure, need to look into that. Is that about the layout mismatch between struct oabi_epoll_event and struct epoll_event? In case of semtimedop... Hell knows, I would probably consider moving that thing into ipc/sem.c under ifdef...
