which return -1 as well as on tier 1 archs. Remove block_userspace_access
used only in these implementations.
(1) These functions may be called in interrupt context and pcb_onfault
can be already set in this time. Thus, prior pcb_onfault must be saved
and restored afterwards.
(2) The check that an abort came either from nested interrupt or while
in critical section or holding not sleepable lock must be avoided for
this case.
These functions are called only for profiling reason, so there will be
only small gain by making the code more complex.