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Message-ID: <YsW18EqSJb/XMLMW@geo.homenetwork>
Date: Thu, 7 Jul 2022 00:18:56 +0800
From: Tao Zhou <tao.zhou@...ux.dev>
To: Daniel Bristot de Oliveira <bristot@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Guenter Roeck <linux@...ck-us.net>,
Jonathan Corbet <corbet@....net>,
Ingo Molnar <mingo@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Marco Elver <elver@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
Shuah Khan <skhan@...uxfoundation.org>,
Gabriele Paoloni <gpaoloni@...hat.com>,
Juri Lelli <juri.lelli@...hat.com>,
Clark Williams <williams@...hat.com>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-trace-devel@...r.kernel.org, Tao Zhou <tao.zhou@...ux.dev>
Subject: Re: [PATCH V4 00/20] The Runtime Verification (RV) interface
Hi Daniel,
After reading things in paper and the previous versions these days slowly
from me, I choose to join the thread this time not because I understand
them clearly. Sorry for not saving your email bandwidth..
On Thu, Jun 16, 2022 at 10:44:42AM +0200, Daniel Bristot de Oliveira wrote:
> 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)
s/trave\(\/events\/rv.h\)/trace\1/
> - 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
>
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