This repository contains a Sail version of the Morello ISA specification, a prototype Armv8-A architecture with CHERI extensions.
The files instrs.sail and v8_base.sail in the src directory contain the
instruction specifications of Morello and the necessary auxiliary functions,
respectively. These Sail files are derived from Arm's ASL specification using
the automatic ASL-to-Sail translation tool. This was done using
a snapshot of ASL files provided by Arm; compared to the version of the
specification available on the Arm website, this snapshot consists
of plain ASL files rather than XML files, and it contains automatically
generated glue code connecting system register accessors and system operations
to the instruction semantics (e.g. AArch64_AutoGen_SysRegRead).
In addition, the src directory in this repository contains a number of Sail
files (handwritten, not derived from ASL and not part of the official
specification) that allow the generation of an executable emulator. In
particular, step.sail contains a simple top-level fetch-decode-execute
function, and impdefs.sail and map_clauses.sail contain some default
choices for implementation-defined behaviour.
The release tarballs on Github contain snapshots of the artifacts generated
from the Sail specification (although for the C emulator, they contain only the
source, no binaries; use the gen_c Makefile target to build a binary).
To freshly build the artifacts, make sure that a recent version of Sail
is installed (last tested using opam version sail.0.17.1), and use the Makefile
target gen_c to generate an emulator, and gen_isa to generate a model for
the Isabelle theorem prover.
Building morello.ir depends additionally on isla-sail:
check out a development version of isla (version tested 1ac01cd),
cd into isla/isla-sail, run make and then from the current path run
PATH=[path to isla-sail]:$PATH make gen_ir.
The boot.sh script downloads, builds, and runs a (non-capability AArch64)
version of Linux above the C emulator.
A formal proof of reachable capability monotonicity, the main intended security property of the Morello architecture, using the Isabelle definitions generated from this model is available here; see also the paper explaining the proof, as well as the automatic generation of a test suite from earlier versions of the Sail model derived from weekly ASL snapshots while the architecture was developed.
The files in this repository are licensed under the BSD 3-Clause Clear license
in LICENSE.