Hi Janis, On Wed, Oct 12, 2022 at 10:56:01PM +0200, Janis Schoetterl-Glausch wrote: > Add cmpxchg functionality similar to that in cmpxchg.h except that the > target is a user space address and that the address' storage key is > matched with the access_key argument in order to honor key-controlled > protection. > The access is performed by changing to the secondary-spaces mode and > setting the PSW key for the duration of the compare and swap. > > Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx> > --- > > > Possible variations: > * check the assumptions made in cmpxchg_user_key_size and error out > * call functions called by copy_to_user > * access_ok? is a nop > * should_fail_usercopy? > * instrument_copy_to_user? doesn't make sense IMO > * don't be overly strict in cmpxchg_user_key > > > arch/s390/include/asm/uaccess.h | 189 ++++++++++++++++++++++++++++++++ > 1 file changed, 189 insertions(+) This not how I would have expected something that would be symmetrical/consistent with what we already have. However instead of spending several iterations I'll send something for this. This might take a bit due to my limited time. So please be patient.
