Fixes a case where a thread can go from Running->Inactive->Restart and
use a restart PC that is out of date. An out of date restart PC occurs
when a thread was transitioned to running after being in a blocked
state, but was never scheduled and so did not execute the traps code
that updates the restart PC.
This also renames relevant register names for consistency across
architectures (FaultIP and NextIP).
Colloquially known as "invert-fastpath".
Update verification efforts on ARM for the following seL4 changes:
- scheduling decisions done in possibleSwitchTo are moved to the
scheduler
- possibleSwitchTo only checks whether the candidate is valid for a
fast switch, not its priority, accepting possible candidates
immmediately as a switch-to scheduler action
- the scheduler checks the candidate against the current thread and
against the bitmaps before making a decision
- attemptSwitchTo and switchIfRequiredTo are gone
- scheduler is now more complicated, and numerous proofs related to it
are rewritten from scratch
- fast path now checks ready queues via the scheduler bitmaps
- L2 scheduler bitmap order reversed for better cache locality
Many iterations between the kernel and verification teams were needed
to get this right.
Gerwin Klein
Gerwin Klein
Corey Lewis
Michael McInerney
Edward Pierzchalski
Rafal Kolanski