The RISC-V calling convention specifies that when a C function takes an
argument by value, the binary function should take the argument by
reference, if the value is larger than 2 pointer words.
For binary verification, we avoid implementing this aspect of the RISC-V
calling convention, by eliminating all such function arguments for
functions which are not inlined. This commit includes the proof updates
corresponding to the kernel source update, which is in the seL4
repository.
This includes arguments of types `slot_range_t` and `extra_caps_t`.
`slot_range_t` is only used in two functions, so for those cases, we
unpack the arguments, and remove the type altogether.
`extra_caps_t` is used extensively in invocation decoding, and also in
inter-process communication. Since extra caps are already stored in a
global variable `current_extra_caps`, we remove the function argument,
and use the global variable instead. However, this adds significant
difficulty to the proofs, because the variable lifting performed by
`cinit` worked for the function argument, but not for the global
variable. We have therefore recently improved the `cinit` automation to
support this change to the kernel.
Even though this change was for the benefit of RISC-V binary
verification, we update all architectures for consistency.
Signed-off-by: Matthew Brecknell <Matthew.Brecknell@data61.csiro.au>
crefine/[ARCH]/Move.thy is replaced with crefine/Move_C.thy
(arch-generic), and crefine/[ARCH]/ArchMove_C.thy (arch-specific).
The only CRefine theory file that imports ArchMove_C is CLevityCatch,
and ArchMove_C imports Move_C which imports "Refine.Refine".
Lemmas found by looking through "FIXME: Move" comments have been added
to either Move_C or ArchMove_C depending on whether it is arch-generic
or arch-specific respectively.
Signed-off-by: Victor Phan <Victor.Phan@data61.csiro.au>
Create ArchMove_R.thy for transporting arch specific lemmas (and generic
lemmas that are used somewhat specifically by one architecture) to theory
files before Refine.
Create Move_R.thy as an arch generic Refine theory file for transporting
generic lemmas to theory files before Refine.
Also delete some lemmas that have existed earlier already or are not
needed.
Rename Move.thy in CRefine to Move_C.thy for consistency.
Prior to this commit the kernel would always trigger a full reschedule
on setPriority. This change allows the kernel to attempt a direct
switch, avoiding invoking the scheduler.
While the numerical value is arch dependent, the definition and symbolic value
are not. This commit factors out the symbolic computation and only unfolds the
numeric value in the architecture dependent spec.
This removes an ifdef present in invokeTCB_(Copy|Write)Registers, and
adds the function Arch_postModifyRegisters which does nothing on any
arch except x86-64.
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.
In X64 update the following to match the C kernel:
- TCB size-bits (11).
- Endpoint size-bits (4).
- Guard bits (58).
- Message registers.
For all architectures, replace magic numbers with defined constants in
specifications, and as far as possible in proofs:
- tcb_bits in abstract spec.
- tcbBlockSizeBits, cteSizeBits, ntfnSizeBits, epSizeBits in Haskell
spec, Haskell and C refinement proofs.
- SELFOUR-30 Reschedule when changing own IPC buffer
Previously if you invoked the TCB of the current thread and
changed the IPC buffer frame this would not immediately take
affect, as the kernels view of the current IPC buffer is
updated in Arch_switchToThread. This change forces Arch_switchToThread
to get called, even if we would switch back to the original
thread.
- SELFOUR-291 Reschedule when changing own registers
Previously if you wrote to TCB of the current thread and
changed the TLS_BASE this would not immediately take
affect, as the kernel only updates this register in
Arch_switchToThread. This change forces Arch_switchToThread
to get called, even if we would switch back to the original
thread.
Gerwin Klein
Florian Haftmann
Matthew Brecknell
Gerwin Klein
Victor Phan
Corey Lewis
MiladKetabi
Amirreza Zarrabi
Edward Pierzchalski
Michael Sproul
Joel Beeren
Rafal Kolanski
Joel Beeren
Alejandro Gomez-Londono
Miki Tanaka
Pang Luo