verification/rvgen: Add support for linear temporal logic

Add support for generating RV monitors from linear temporal logic, similar
to the generation of deterministic automaton monitors.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/f3c63b363ff9c5af3302ba2b5d92a26a98700eaf.1751634289.git.namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/verification/rvgen/.gitignore

@@ -0,0 +1,3 @@
+__pycache__/
+parser.out
+parsetab.py

tools/verification/rvgen/Makefile

@@ -21,5 +21,7 @@ install:
 	$(INSTALL) rvgen/dot2k.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/dot2k.py
 	$(INSTALL) rvgen/container.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/container.py
 	$(INSTALL) rvgen/generator.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/generator.py
+	$(INSTALL) rvgen/ltl2ba.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/ltl2ba.py
+	$(INSTALL) rvgen/ltl2k.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/ltl2k.py
 	$(INSTALL) __main__.py -D -m 755 $(DESTDIR)$(bindir)/rvgen
 	cp -rp rvgen/templates $(DESTDIR)$(PYLIB)/rvgen/

tools/verification/rvgen/__main__.py

@@ -12,6 +12,7 @@ if __name__ == '__main__':
     from rvgen.dot2k import dot2k
     from rvgen.generator import Monitor
     from rvgen.container import Container
+    from rvgen.ltl2k import ltl2k
     import argparse
     import sys
 
@@ -44,7 +45,7 @@ if __name__ == '__main__':
             if params.monitor_class == "da":
                 monitor = dot2k(params.spec, params.monitor_type, vars(params))
             elif params.monitor_class == "ltl":
-                raise NotImplementedError
+                monitor = ltl2k(params.spec, params.monitor_type, vars(params))
             else:
                 print("Unknown monitor class:", params.monitor_class)
                 sys.exit(1)

tools/verification/rvgen/rvgen/ltl2k.py

@@ -0,0 +1,252 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-only
+
+from pathlib import Path
+from . import generator
+from . import ltl2ba
+
+COLUMN_LIMIT = 100
+
+def line_len(line: str) -> int:
+    tabs = line.count('\t')
+    return tabs * 7 + len(line)
+
+def break_long_line(line: str, indent='') -> list[str]:
+    result = []
+    while line_len(line) > COLUMN_LIMIT:
+        i = line[:COLUMN_LIMIT - line_len(line)].rfind(' ')
+        result.append(line[:i])
+        line = indent + line[i + 1:]
+    if line:
+        result.append(line)
+    return result
+
+def build_condition_string(node: ltl2ba.GraphNode):
+    if not node.labels:
+        return "(true)"
+
+    result = "("
+
+    first = True
+    for label in sorted(node.labels):
+        if not first:
+            result += " && "
+        result += label
+        first = False
+
+    result += ")"
+
+    return result
+
+def abbreviate_atoms(atoms: list[str]) -> list[str]:
+    def shorten(s: str) -> str:
+        skip = ["is", "by", "or", "and"]
+        return '_'.join([x[:2] for x in s.lower().split('_') if x not in skip])
+
+    abbrs = []
+    for atom in atoms:
+        for i in range(len(atom), -1, -1):
+            if sum(a.startswith(atom[:i]) for a in atoms) > 1:
+                break
+        share = atom[:i]
+        unique = atom[i:]
+        abbrs.append((shorten(share) + shorten(unique)))
+    return abbrs
+
+class ltl2k(generator.Monitor):
+    template_dir = "ltl2k"
+
+    def __init__(self, file_path, MonitorType, extra_params={}):
+        if MonitorType != "per_task":
+            raise NotImplementedError("Only per_task monitor is supported for LTL")
+        super().__init__(extra_params)
+        with open(file_path) as f:
+            self.atoms, self.ba, self.ltl = ltl2ba.create_graph(f.read())
+        self.atoms_abbr = abbreviate_atoms(self.atoms)
+        self.name = extra_params.get("model_name")
+        if not self.name:
+            self.name = Path(file_path).stem
+
+    def _fill_states(self) -> str:
+        buf = [
+            "enum ltl_buchi_state {",
+        ]
+
+        for node in self.ba:
+            buf.append("\tS%i," % node.id)
+        buf.append("\tRV_NUM_BA_STATES")
+        buf.append("};")
+        buf.append("static_assert(RV_NUM_BA_STATES <= RV_MAX_BA_STATES);")
+        return buf
+
+    def _fill_atoms(self):
+        buf = ["enum ltl_atom {"]
+        for a in sorted(self.atoms):
+            buf.append("\tLTL_%s," % a)
+        buf.append("\tLTL_NUM_ATOM")
+        buf.append("};")
+        buf.append("static_assert(LTL_NUM_ATOM <= RV_MAX_LTL_ATOM);")
+        return buf
+
+    def _fill_atoms_to_string(self):
+        buf = [
+            "static const char *ltl_atom_str(enum ltl_atom atom)",
+            "{",
+            "\tstatic const char *const names[] = {"
+        ]
+
+        for name in self.atoms_abbr:
+            buf.append("\t\t\"%s\"," % name)
+
+        buf.extend([
+            "\t};",
+            "",
+            "\treturn names[atom];",
+            "}"
+        ])
+        return buf
+
+    def _fill_atom_values(self):
+        buf = []
+        for node in self.ltl:
+            if node.op.is_temporal():
+                continue
+
+            if isinstance(node.op, ltl2ba.Variable):
+                buf.append("\tbool %s = test_bit(LTL_%s, mon->atoms);" % (node, node.op.name))
+            elif isinstance(node.op, ltl2ba.AndOp):
+                buf.append("\tbool %s = %s && %s;" % (node, node.op.left, node.op.right))
+            elif isinstance(node.op, ltl2ba.OrOp):
+                buf.append("\tbool %s = %s || %s;" % (node, node.op.left, node.op.right))
+            elif isinstance(node.op, ltl2ba.NotOp):
+                buf.append("\tbool %s = !%s;" % (node, node.op.child))
+        buf.reverse()
+
+        buf2 = []
+        for line in buf:
+            buf2.extend(break_long_line(line, "\t     "))
+        return buf2
+
+    def _fill_transitions(self):
+        buf = [
+            "static void",
+            "ltl_possible_next_states(struct ltl_monitor *mon, unsigned int state, unsigned long *next)",
+            "{"
+        ]
+        buf.extend(self._fill_atom_values())
+        buf.extend([
+            "",
+            "\tswitch (state) {"
+        ])
+
+        for node in self.ba:
+            buf.append("\tcase S%i:" % node.id)
+
+            for o in sorted(node.outgoing):
+                line   = "\t\tif "
+                indent = "\t\t   "
+
+                line += build_condition_string(o)
+                lines = break_long_line(line, indent)
+                buf.extend(lines)
+
+                buf.append("\t\t\t__set_bit(S%i, next);" % o.id)
+            buf.append("\t\tbreak;")
+        buf.extend([
+            "\t}",
+            "}"
+        ])
+
+        return buf
+
+    def _fill_start(self):
+        buf = [
+            "static void ltl_start(struct task_struct *task, struct ltl_monitor *mon)",
+            "{"
+        ]
+        buf.extend(self._fill_atom_values())
+        buf.append("")
+
+        for node in self.ba:
+            if not node.init:
+                continue
+
+            line   = "\tif "
+            indent = "\t   "
+
+            line += build_condition_string(node)
+            lines = break_long_line(line, indent)
+            buf.extend(lines)
+
+            buf.append("\t\t__set_bit(S%i, mon->states);" % node.id)
+        buf.append("}")
+        return buf
+
+    def fill_tracepoint_handlers_skel(self):
+        buff = []
+        buff.append("static void handle_example_event(void *data, /* XXX: fill header */)")
+        buff.append("{")
+        buff.append("\tltl_atom_update(task, LTL_%s, true/false);" % self.atoms[0])
+        buff.append("}")
+        buff.append("")
+        return '\n'.join(buff)
+
+    def fill_tracepoint_attach_probe(self):
+        return "\trv_attach_trace_probe(\"%s\", /* XXX: tracepoint */, handle_example_event);" \
+                % self.name
+
+    def fill_tracepoint_detach_helper(self):
+        return "\trv_detach_trace_probe(\"%s\", /* XXX: tracepoint */, handle_sample_event);" \
+                % self.name
+
+    def fill_atoms_init(self):
+        buff = []
+        for a in self.atoms:
+            buff.append("\tltl_atom_set(mon, LTL_%s, true/false);" % a)
+        return '\n'.join(buff)
+
+    def fill_model_h(self):
+        buf = [
+            "/* SPDX-License-Identifier: GPL-2.0 */",
+            "",
+            "/*",
+            " * C implementation of Buchi automaton, automatically generated by",
+            " * tools/verification/rvgen from the linear temporal logic specification.",
+            " * For further information, see kernel documentation:",
+            " *   Documentation/trace/rv/linear_temporal_logic.rst",
+            " */",
+            "",
+            "#include <linux/rv.h>",
+            "",
+            "#define MONITOR_NAME " + self.name,
+            ""
+        ]
+
+        buf.extend(self._fill_atoms())
+        buf.append('')
+
+        buf.extend(self._fill_atoms_to_string())
+        buf.append('')
+
+        buf.extend(self._fill_states())
+        buf.append('')
+
+        buf.extend(self._fill_start())
+        buf.append('')
+
+        buf.extend(self._fill_transitions())
+        buf.append('')
+
+        return '\n'.join(buf)
+
+    def fill_monitor_class_type(self):
+        return "LTL_MON_EVENTS_ID"
+
+    def fill_monitor_class(self):
+        return "ltl_monitor_id"
+
+    def fill_main_c(self):
+        main_c = super().fill_main_c()
+        main_c = main_c.replace("%%ATOMS_INIT%%", self.fill_atoms_init())
+
+        return main_c

tools/verification/rvgen/rvgen/templates/ltl2k/main.c

@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+
+#define MODULE_NAME "%%MODEL_NAME%%"
+
+/*
+ * XXX: include required tracepoint headers, e.g.,
+ * #include <trace/events/sched.h>
+ */
+#include <rv_trace.h>
+%%INCLUDE_PARENT%%
+
+/*
+ * This is the self-generated part of the monitor. Generally, there is no need
+ * to touch this section.
+ */
+#include "%%MODEL_NAME%%.h"
+#include <rv/ltl_monitor.h>
+
+static void ltl_atoms_fetch(struct task_struct *task, struct ltl_monitor *mon)
+{
+	/*
+	 * This is called everytime the Buchi automaton is triggered.
+	 *
+	 * This function could be used to fetch the atomic propositions which
+	 * are expensive to trace. It is possible only if the atomic proposition
+	 * does not need to be updated at precise time.
+	 *
+	 * It is recommended to use tracepoints and ltl_atom_update() instead.
+	 */
+}
+
+static void ltl_atoms_init(struct task_struct *task, struct ltl_monitor *mon, bool task_creation)
+{
+	/*
+	 * This should initialize as many atomic propositions as possible.
+	 *
+	 * @task_creation indicates whether the task is being created. This is
+	 * false if the task is already running before the monitor is enabled.
+	 */
+%%ATOMS_INIT%%
+}
+
+/*
+ * This is the instrumentation part of the monitor.
+ *
+ * This is the section where manual work is required. Here the kernel events
+ * are translated into model's event.
+ */
+%%TRACEPOINT_HANDLERS_SKEL%%
+static int enable_%%MODEL_NAME%%(void)
+{
+	int retval;
+
+	retval = ltl_monitor_init();
+	if (retval)
+		return retval;
+
+%%TRACEPOINT_ATTACH%%
+
+	return 0;
+}
+
+static void disable_%%MODEL_NAME%%(void)
+{
+%%TRACEPOINT_DETACH%%
+
+	ltl_monitor_destroy();
+}
+
+/*
+ * This is the monitor register section.
+ */
+static struct rv_monitor rv_%%MODEL_NAME%% = {
+	.name = "%%MODEL_NAME%%",
+	.description = "%%DESCRIPTION%%",
+	.enable = enable_%%MODEL_NAME%%,
+	.disable = disable_%%MODEL_NAME%%,
+};
+
+static int __init register_%%MODEL_NAME%%(void)
+{
+	return rv_register_monitor(&rv_%%MODEL_NAME%%, %%PARENT%%);
+}
+
+static void __exit unregister_%%MODEL_NAME%%(void)
+{
+	rv_unregister_monitor(&rv_%%MODEL_NAME%%);
+}
+
+module_init(register_%%MODEL_NAME%%);
+module_exit(unregister_%%MODEL_NAME%%);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR(/* TODO */);
+MODULE_DESCRIPTION("%%MODEL_NAME%%: %%DESCRIPTION%%");

tools/verification/rvgen/rvgen/templates/ltl2k/trace.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_%%MODEL_NAME_UP%%
+DEFINE_EVENT(event_%%MONITOR_CLASS%%, event_%%MODEL_NAME%%,
+	     TP_PROTO(struct task_struct *task, char *states, char *atoms, char *next),
+	     TP_ARGS(task, states, atoms, next));
+DEFINE_EVENT(error_%%MONITOR_CLASS%%, error_%%MODEL_NAME%%,
+	     TP_PROTO(struct task_struct *task),
+	     TP_ARGS(task));
+#endif /* CONFIG_RV_MON_%%MODEL_NAME_UP%% */