[PATCH V4 00/20] The Runtime Verification (RV) interface

[Daniel Bristot de Oliveira <bristot@kernel.org>]

Over the last years, I've been exploring the possibility of
verifying the Linux kernel behavior using Runtime Verification.

Runtime Verification (RV) is a lightweight (yet rigorous) method that
complements classical exhaustive verification techniques (such as model
checking and theorem proving) with a more practical approach for complex
systems.

Instead of relying on a fine-grained model of a system (e.g., a
re-implementation a instruction level), RV works by analyzing the trace of the
system's actual execution, comparing it against a formal specification of
the system behavior.

The usage of deterministic automaton for RV is a well-established
approach. In the specific case of the Linux kernel, you can check how
to model complex behavior of the Linux kernel with this paper:

  DE OLIVEIRA, Daniel Bristot; CUCINOTTA, Tommaso; DE OLIVEIRA, Romulo Silva.
  *Efficient formal verification for the Linux kernel.* In: International
  Conference on Software Engineering and Formal Methods. Springer, Cham, 2019.
  p. 315-332.

And how efficient is this approach here:

  DE OLIVEIRA, Daniel B.; DE OLIVEIRA, Romulo S.; CUCINOTTA, Tommaso. *A thread
  synchronization model for the PREEMPT_RT Linux kernel.* Journal of Systems
  Architecture, 2020, 107: 101729.

tlrd: it is possible to model complex behaviors in a modular way, with
an acceptable overhead (even for production systems). See this
presentation at 2019's ELCE: https://www.youtube.com/watch?v=BfTuEHafNgg

Here I am proposing a more practical approach for the usage of deterministic
automata for runtime verification, and it includes:

	- An interface for controlling the verification;
	- A tool and set of headers that enables the automatic code
	  generation of the RV monitor (Monitor Synthesis);
	- Sample monitors to evaluate the interface;
	- A sample monitor developed in the context of the Elisa Project
	  demonstrating how to use RV in the context of safety-critical
	  systems.

Given that RV is a tracing consumer, the code is being placed inside the
tracing subsystem (Steven and I have been talking about it for a while).

Changes from v3:
	- Rebased on 5.19
	(rostedt's request were made on 1x1 meetings)
	- Moved monitors to monitors/$name/ (Rostedt)
	- Consolidate the tracepoints into a single include file in the default
	  directory (trave/events/rv.h) (Rostedt)
	- The tracepoints now record the entire string to the buffer.
	- Change the enable_monitors to disable monitors with ! (instead of -).
	  (Rostedt)
	- Add a suffix to the state/events enums, to avoid conflict in the
	  vmlinux.h used by eBPF.
	- The models are now placed in the $name.h (it used to store the
	  tracepoints, but they are now consolidated in a single file)
	- dot2c and dot2k updated to the changes
	- models re-generated with these new standards.
	- user-space tools moved to an directory outside of tools/tracing as
	  other methods of verification/log sources are planned.
Changes from v2:
	- Tons of checkpatch and kernel test robot
	- Moved files to better places
	- Adjusted watchdog tracepoints patch (Guenter Roeck)
	- Added pretimeout watchdog events (Peter Enderborg) 
	- Used task struct to store per-task monitors (Peter Zijlstra)
	- Changed the instrumentation to use internal definition of tracepoint
	  and check the callback signature (Steven Rostedt)
	- Used printk_deferred() and removed the comment about deadlocks
	  (Shuah Khan/John Ogness)
	- Some simplifications:
		- Removed the safe watchdog nowayout for now (myself)
		- Removed export symbols for now (myself)
Changes from V1:
	- rebased to the latest kernel;
	- code cleanup;
	- the watchdog dev monitor;
	- safety app;

Things kept for a second moment (after this patchset):
	- Add a reactor tha enables the visualization of the visited
	  states via KCOV (Marco Elver & Dmitry Vyukov)
	- Add a CRC method to check from user-space if the values
	  exported by the monitor were not corrupted by any other
	  kernel task (Gabriele Paoloni)
	- Export symbols for external modules
	- dot2bpf

Daniel Bristot de Oliveira (20):
  rv: Add Runtime Verification (RV) interface
  rv: Add runtime reactors interface
  rv/include: Add helper functions for deterministic automata
  rv/include: Add deterministic automata monitor definition via C macros
  rv/include: Add instrumentation helper functions
  tools/rv: Add dot2c
  tools/rv: Add dot2k
  rv/monitor: Add the wip monitor skeleton created by dot2k
  rv/monitor: wip instrumentation and Makefile/Kconfig entries
  rv/monitor: Add the wwnr monitor skeleton created by dot2k
  rv/monitor: wwnr instrumentation and Makefile/Kconfig entries
  rv/reactor: Add the printk reactor
  rv/reactor: Add the panic reactor
  Documentation/rv: Add a basic documentation
  Documentation/rv: Add deterministic automata monitor synthesis
    documentation
  Documentation/rv: Add deterministic automata instrumentation
    documentation
  watchdog/dev: Add tracepoints
  rv/monitor: Add safe watchdog monitor
  rv/safety_app: Add a safety_app sample
  Documentation/rv: Add watchdog-monitor documentation

 Documentation/trace/index.rst                 |   1 +
 .../trace/rv/da_monitor_instrumentation.rst   | 223 ++++++
 .../trace/rv/da_monitor_synthesis.rst         | 284 +++++++
 Documentation/trace/rv/index.rst              |   9 +
 .../trace/rv/runtime-verification.rst         | 233 ++++++
 Documentation/trace/rv/watchdog-monitor.rst   | 250 ++++++
 drivers/watchdog/watchdog_dev.c               |  43 +-
 drivers/watchdog/watchdog_pretimeout.c        |   2 +
 include/linux/rv.h                            |  38 +
 include/linux/sched.h                         |  11 +
 include/linux/watchdog.h                      |   7 +-
 include/rv/automata.h                         |  49 ++
 include/rv/da_monitor.h                       | 419 ++++++++++
 include/rv/instrumentation.h                  |  23 +
 include/rv/rv.h                               |  32 +
 include/trace/events/rv.h                     | 153 ++++
 include/trace/events/watchdog.h               | 101 +++
 kernel/fork.c                                 |  14 +
 kernel/trace/Kconfig                          |   2 +
 kernel/trace/Makefile                         |   2 +
 kernel/trace/rv/Kconfig                       |  84 ++
 kernel/trace/rv/Makefile                      |   9 +
 kernel/trace/rv/monitors/safe_wtd/safe_wtd.c  | 300 +++++++
 kernel/trace/rv/monitors/safe_wtd/safe_wtd.h  |  84 ++
 kernel/trace/rv/monitors/wip/wip.c            | 110 +++
 kernel/trace/rv/monitors/wip/wip.h            |  38 +
 kernel/trace/rv/monitors/wwnr/wwnr.c          | 109 +++
 kernel/trace/rv/monitors/wwnr/wwnr.h          |  38 +
 kernel/trace/rv/reactor_panic.c               |  44 +
 kernel/trace/rv/reactor_printk.c              |  43 +
 kernel/trace/rv/rv.c                          | 757 ++++++++++++++++++
 kernel/trace/rv/rv.h                          |  54 ++
 kernel/trace/rv/rv_reactors.c                 | 476 +++++++++++
 kernel/trace/trace.c                          |   4 +
 kernel/trace/trace.h                          |   2 +
 tools/verification/dot2/Makefile              |  26 +
 tools/verification/dot2/automata.py           | 179 +++++
 tools/verification/dot2/dot2c                 |  30 +
 tools/verification/dot2/dot2c.py              | 244 ++++++
 tools/verification/dot2/dot2k                 |  50 ++
 tools/verification/dot2/dot2k.py              | 177 ++++
 .../dot2/dot2k_templates/main_global.c        |  94 +++
 .../dot2/dot2k_templates/main_per_cpu.c       |  94 +++
 .../dot2/dot2k_templates/main_per_task.c      |  94 +++
 tools/verification/safety_app/Makefile        |  51 ++
 tools/verification/safety_app/safety_app.c    | 614 ++++++++++++++
 46 files changed, 5691 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/trace/rv/da_monitor_instrumentation.rst
 create mode 100644 Documentation/trace/rv/da_monitor_synthesis.rst
 create mode 100644 Documentation/trace/rv/index.rst
 create mode 100644 Documentation/trace/rv/runtime-verification.rst
 create mode 100644 Documentation/trace/rv/watchdog-monitor.rst
 create mode 100644 include/linux/rv.h
 create mode 100644 include/rv/automata.h
 create mode 100644 include/rv/da_monitor.h
 create mode 100644 include/rv/instrumentation.h
 create mode 100644 include/rv/rv.h
 create mode 100644 include/trace/events/rv.h
 create mode 100644 include/trace/events/watchdog.h
 create mode 100644 kernel/trace/rv/Kconfig
 create mode 100644 kernel/trace/rv/Makefile
 create mode 100644 kernel/trace/rv/monitors/safe_wtd/safe_wtd.c
 create mode 100644 kernel/trace/rv/monitors/safe_wtd/safe_wtd.h
 create mode 100644 kernel/trace/rv/monitors/wip/wip.c
 create mode 100644 kernel/trace/rv/monitors/wip/wip.h
 create mode 100644 kernel/trace/rv/monitors/wwnr/wwnr.c
 create mode 100644 kernel/trace/rv/monitors/wwnr/wwnr.h
 create mode 100644 kernel/trace/rv/reactor_panic.c
 create mode 100644 kernel/trace/rv/reactor_printk.c
 create mode 100644 kernel/trace/rv/rv.c
 create mode 100644 kernel/trace/rv/rv.h
 create mode 100644 kernel/trace/rv/rv_reactors.c
 create mode 100644 tools/verification/dot2/Makefile
 create mode 100644 tools/verification/dot2/automata.py
 create mode 100644 tools/verification/dot2/dot2c
 create mode 100644 tools/verification/dot2/dot2c.py
 create mode 100644 tools/verification/dot2/dot2k
 create mode 100644 tools/verification/dot2/dot2k.py
 create mode 100644 tools/verification/dot2/dot2k_templates/main_global.c
 create mode 100644 tools/verification/dot2/dot2k_templates/main_per_cpu.c
 create mode 100644 tools/verification/dot2/dot2k_templates/main_per_task.c
 create mode 100644 tools/verification/safety_app/Makefile
 create mode 100644 tools/verification/safety_app/safety_app.c

-- 
2.35.1