These changes to the automatons are required by:
SELFOUR-242: invert bitfield scheduler and optimise fast path
Details:
When we enter the kernel, the domain time left (ksDomainTime) is never zero.
If we entered on a timer interrupt, we may decrement it to zero before the
scheduler runs. If we do so, we set the scheduler state to choose_new_thread.
When choosing a new thread, the scheduler switches to a new domain if the
present one is required, and sets the new domain time left from domain_list
(ksDomSchedule).
When entering the kernel on a non-interrupt event, we never touch the domain
time left, which trivially preserves the new constraints.
To prove these, we had to ban a transition from kernel entry to kernel being
preempted when handling an interrupt event in InfoFlow. This is fine, as by
design handling interrupts is not meant to be preempted by interrupts.
To finish the proof of refinement to C, the specification for checkPrio
needed strengthening: the checkPrio spec now takes a machine word
argument. In the spec, priorities are still stored as 8-bit quantities,
however. Once the spec was strenthened, it was possible to remove some
redundant checks and mask operations from the C code.
A thread's maximum controlled priority (MCP) determines the maximum
thread priority or MCP it can assign to another thread (or itself).
* commit 'ecbb860532b4c576fc4726a805802f16bcf5302c': (29 commits)
autocorres-crefine: specialise corres_no_failI for compatibility with Refine
Add license tags for autocorres-crefine files
crefine: refactor AutoCorresTest a bit
autocorres-crefine: remove local debugging imports
Fix InfoFlowC to accommodate corres_underlying changes.
Fix DRefine to accommodate corres_underlying changes.
autocorres-crefine: experiment with manually translating a function (clzl).
autocorres-crefine: experiment with translating bitfield_gen specs.
autocorres-crefine: start a test case for function calls.
autocorres-crefine: update example proofs to work with no_c_termination, which does not require proving termination for the C spec.
autocorres: add user option "no_c_termination" for previous patch.
Making termination proof optional for AutoCorres.
WIP: autocorres: hacky proof of concept for incremental translation.
autocorres: add some missing WordAbstract rules.
autocorres-crefine: fix some comments in work theory.
autocorres-crefine: prove modifies and (simple) terminates specs.
autocorres-crefine: experiment with generating modifies proofs
autocorres-crefine: run autocorres in kernel_all_substitute locale
autocorres-crefine: update another corres_UL that snuck in before rebasing.
autocorres-crefine: working ccorres for handleYield (modulo some white lies).
...
Green build except for:
CParserTest (WTF Duplicate fact declaration "dc_20081211.dc_20081211.test_modifies")
AutoCorresSEL4 (waiting on result)
There is still a carefully managed sorry in Schedule_R, waiting on the C
parser FNSPEC+DONT_TRANSLATE fix.
This commit should at least remove merge conflict markers, and the idea
is that at least refine, crefine, drefine, and infoflow (with sorrys)
build. Subsequent commits may be required to fix build issues that I
have not picked up.
UserOp_IF had its own way of extracting the XN bit from page tables.
This is now unified with the existing functions in ADT_AI, which also
means that the proof for XN bit equality is basically the same as for
pt_rights and pt_lift.
Some of the noninterference results depend on executions at the haskell level starting at a valid initial state. This file demonstrates this condition being realised.
The fact that the C infoflow adt refines the abstract infoflow adt now only requires that given user operation is nonempty and not sane (nonempty and doesn't return an interrupt).
Also added some more general lemmas about fw_sim and refinement to lib/Simulation.thy.
...and clean up some fallout.
In particular, we now say that the output of "nat_to_bl sz n" is taken
to be the bitlist of "n mod 2^sz", so the output is always defined.
The idea is to remove the undefinedness of "the_nat_to_bl" so that it is
easier to generate simp rules for it; some of these are developed in the
theory below, and simplify some of the more concrete infoflow proofs.
Use the previously-added "distinct" command to simplify the
"Example_Valid_State" proof. This brings quite significant speedups as
it means that raw definitions need not be unfolded, and hence automated
tactics don't get side-tracked with their numerical definitions.
Joel Beeren
Rafal Kolanski
Thomas Sewell
Matthew Brecknell
Xin,Gao
Matthew Brecknell
Miki Tanaka
Japheth Lim
Gerwin Klein
Daniel Matichuk
Sophie Taylor
Ramana Kumar
Matthew Fernandez
Daniel Matichuk
deang
David Greenaway