[PATCH v4 09/17] verification/rvgen: Add the rvgen kunit subcommand

[Gabriele Monaco <gmonaco@redhat.com>]

Add the rvgen kunit subcommand to patch an already generated monitor for
kunit support. It parses the handlers and create the necessary structs
and initialisations.

The only remaining manual steps are importing the test in the runner
and writing the test itself.

Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---

Notes:
    V4:
    * Use pathlib instead of os.path
    * Rename files to backup instead of writing to backup

 tools/verification/rvgen/Makefile             |   1 +
 tools/verification/rvgen/__main__.py          |  15 +-
 tools/verification/rvgen/rvgen/generator.py   |   4 +-
 tools/verification/rvgen/rvgen/kunit.py       | 194 ++++++++++++++++++
 .../rvgen/rvgen/templates/kunit.c             |  29 +++
 5 files changed, 240 insertions(+), 3 deletions(-)
 create mode 100644 tools/verification/rvgen/rvgen/kunit.py
 create mode 100644 tools/verification/rvgen/rvgen/templates/kunit.c

diff --git a/tools/verification/rvgen/Makefile b/tools/verification/rvgen/Makefile
index 2a2b9e64ea42..48d0376a5cc4 100644
--- a/tools/verification/rvgen/Makefile
+++ b/tools/verification/rvgen/Makefile
@@ -23,6 +23,7 @@ install:
 	$(INSTALL) rvgen/dot2c.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/dot2c.py
 	$(INSTALL) dot2c -D -m 755 $(DESTDIR)$(bindir)/
 	$(INSTALL) rvgen/dot2k.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/dot2k.py
+	$(INSTALL) rvgen/kunit.py -D -m 644 $(DESTDIR)$(PYLIB)/rvgen/kunit.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
diff --git a/tools/verification/rvgen/__main__.py b/tools/verification/rvgen/__main__.py
index 5c923dc10d0f..e0ac562fbddd 100644
--- a/tools/verification/rvgen/__main__.py
+++ b/tools/verification/rvgen/__main__.py
@@ -13,6 +13,7 @@ if __name__ == '__main__':
     from rvgen.generator import Monitor
     from rvgen.container import Container
     from rvgen.ltl2k import ltl2k
+    from rvgen.kunit import KUnit, KUnitError
     from rvgen.automata import AutomataError
     import argparse
     import sys
@@ -41,6 +42,11 @@ if __name__ == '__main__':
     container_parser = subparsers.add_parser("container", parents=[parent_parser])
     container_parser.add_argument('-n', "--model_name", dest="model_name", required=True)
 
+    kunit_parser = subparsers.add_parser("kunit", parents=[parent_parser])
+    kunit_parser.add_argument('-n', "--model_name", dest="model_name", required=True)
+    kunit_parser.add_argument('-l', "--local", dest="local", action="store_true", required=False,
+                               help="Force looking for the monitor in the current directory only")
+
     params = parser.parse_args()
 
     try:
@@ -55,11 +61,18 @@ if __name__ == '__main__':
             else:
                 print("Unknown monitor class:", params.monitor_class)
                 sys.exit(1)
-        else:
+        elif params.subcmd == "container":
             monitor = Container(vars(params))
+        elif params.subcmd == "kunit":
+            monitor = KUnit(vars(params))
+            monitor.print_files()
+            sys.exit(0)
     except AutomataError as e:
         print(f"There was an error processing {params.spec}: {e}", file=sys.stderr)
         sys.exit(1)
+    except KUnitError as e:
+        print(f"There was an error generating KUnit files: {e}", file=sys.stderr)
+        sys.exit(1)
 
     print(f"Writing the monitor into the directory {monitor.name}")
     monitor.print_files()
diff --git a/tools/verification/rvgen/rvgen/generator.py b/tools/verification/rvgen/rvgen/generator.py
index f1b37d34b1e9..45e2bab26cb5 100644
--- a/tools/verification/rvgen/rvgen/generator.py
+++ b/tools/verification/rvgen/rvgen/generator.py
@@ -22,9 +22,9 @@ class RVGenerator:
         self.description = extra_params.get("description", self.name) or "auto-generated"
         self.auto_patch = extra_params.get("auto_patch")
         if self.auto_patch:
-            self.__fill_rv_kernel_dir()
+            self._fill_rv_kernel_dir()
 
-    def __fill_rv_kernel_dir(self):
+    def _fill_rv_kernel_dir(self):
         # find the kernel tree root relative to this file's location
         resolved_path = Path(__file__).resolve()
         if len(resolved_path.parents) > 4:
diff --git a/tools/verification/rvgen/rvgen/kunit.py b/tools/verification/rvgen/rvgen/kunit.py
new file mode 100644
index 000000000000..ed2082d7d3bc
--- /dev/null
+++ b/tools/verification/rvgen/rvgen/kunit.py
@@ -0,0 +1,194 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright (C) 2026-2029 Red Hat, Inc. Gabriele Monaco <gmonaco@redhat.com>
+#
+# Generator for runtime verification kunit files
+
+import re
+from pathlib import Path
+from . import generator
+
+
+class KUnitError(Exception):
+    """Exception raised for errors in KUnit generation and file handling."""
+
+
+class KUnit(generator.RVGenerator):
+    template_dir = ""
+
+    def __init__(self, extra_params={}):
+        super().__init__(extra_params)
+        self.local = extra_params.get("local", False)
+        self.kunit_c = self._read_template_file("kunit.c")
+        if not self.local:
+            self._fill_rv_kernel_dir()
+        try:
+            self.monitor_path = self.__find_monitor_c_file()
+            with open(self.monitor_path, 'r') as f:
+                self.content = f.read()
+        except OSError as e:
+            raise KUnitError(e) from e
+        self.monitor_class = self.__detect_monitor_class()
+
+    def _read_template_file(self, file):
+        if file in ("main.c", "Kconfig"):
+            return ""
+        return super()._read_template_file(file)
+
+    def __find_monitor_c_file(self) -> str:
+        """Look for the monitor file in the kernel tree or in the current folder."""
+        if not self.local:
+            path = Path(self.rv_dir) / "monitors" / self.name / f"{self.name}.c"
+            if path.exists():
+                return str(path)
+
+        path = Path(self.name) / f"{self.name}.c"
+        if path.exists():
+            return str(path)
+
+        raise FileNotFoundError(f"Could not find monitor C file for '{self.name}'")
+
+    def __extract_function_args(self, handler_name: str) -> str:
+        pattern = re.compile(
+            r'^\s*(.*?)\b' + re.escape(handler_name) + r'\(([^)]*)\)',
+            re.MULTILINE | re.DOTALL
+        )
+        match = pattern.search(self.content)
+        if not match:
+            return "/* XXX: fill handlers argument. */"
+
+        return match.group(2).strip()
+
+    def __parse_attach_handlers(self) -> list[str]:
+        """Find handlers by parsing when they are attached to tracepoints."""
+        probe_pattern = re.compile(
+            r'rv_attach_trace_probe\(.*, ([a-zA-Z0-9_]+)\)'
+        )
+        handlers = []
+        for match in probe_pattern.finditer(self.content):
+            handler = match.group(1)
+            if handler not in handlers:
+                handlers.append(handler)
+        return handlers
+
+    def __detect_monitor_class(self) -> str:
+        for c in ("da", "ha", "ltl"):
+            if f"{c}_monitor.h" in self.content:
+                return c
+        return "da"
+
+    def __fill_kunit_c(self, struct_name: str) -> str:
+        kunit_c = self.kunit_c
+        kunit_c = kunit_c.replace("%%MODEL_NAME%%", self.name)
+        kunit_c = kunit_c.replace("%%MODEL_NAME_UP%%", self.name.upper())
+        kunit_c = kunit_c.replace("%%MONITOR_CLASS%%", self.monitor_class)
+        kunit_c = kunit_c.replace("%%STRUCT_NAME%%", struct_name)
+        return kunit_c
+
+    def __fill_kunit_h(self, struct_name, prototypes) -> str:
+        return f"""/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Automatically generated by rvgen kunit.
+ * May need manual intervention for function prototypes that couldn't be
+ * found (e.g. are in another file) or variables to be exported.
+ */
+
+#ifndef __{self.name.upper()}_KUNIT_H
+#define __{self.name.upper()}_KUNIT_H
+
+#if IS_ENABLED(CONFIG_RV_MONITORS_KUNIT_TEST)
+
+#include <linux/rv.h>
+#include <rv/kunit.h>
+
+extern const struct {struct_name} {{
+\tstruct rv_kunit_mon mon;
+\t{"\n\t".join(prototypes)}
+}} {struct_name};
+#endif
+
+#endif /* __{self.name.upper()}_KUNIT_H */
+"""
+
+    def __fill_monitor_handlers(self, struct_name, assignments):
+        struct_definition = f"""#if IS_ENABLED(CONFIG_RV_MONITORS_KUNIT_TEST)
+#include <kunit/visibility.h>
+#include "{self.name}_kunit.h"
+
+const struct {struct_name} {struct_name} = {{
+\t.mon = RV_MON_OPS_INIT(),
+\t{"\n\t".join(assignments)}
+}};
+EXPORT_SYMBOL_IF_KUNIT({struct_name});
+#endif"""
+
+        if self.auto_patch:
+            try:
+                with open(self.monitor_path, 'w') as f:
+                    f.write(f"{self.content}\n{struct_definition}\n")
+            except OSError as e:
+                raise KUnitError(f"Error patching monitor file {self.monitor_path}: {e}") from e
+        else:
+            print(f"Append the following to {self.name}.c:\n")
+            print(struct_definition)
+        print("Now complete the test and add it to rv_monitors_test.c")
+
+    def print_files(self):
+
+        handlers = self.__parse_attach_handlers()
+
+        if not handlers:
+            raise KUnitError(f"No handlers found in {self.monitor_path}")
+
+        prototypes = []
+        assignments = []
+        for handler in handlers:
+            arguments = self.__extract_function_args(handler)
+
+            prototypes.append(f"void (*{handler})({arguments});")
+            assignments.append(f".{handler} = {handler},")
+
+        struct_name = f"rv_{self.name}_ops"
+
+        self.__fill_monitor_handlers(struct_name, assignments)
+
+        dir_path = Path(self.monitor_path).parent
+
+        header_file_path = dir_path / f"{self.name}_kunit.h"
+        kunit_c_file_path = dir_path / f"{self.name}_kunit.c"
+
+        use_backup = True
+        if header_file_path.exists() or kunit_c_file_path.exists():
+            try:
+                response = input("KUnit file(s) already exist. Backup? [Y/n] ")
+                if response.strip().lower() in ("n", "no"):
+                    use_backup = False
+            except EOFError:
+                print("Non-interactive session detected, backing up existing files.")
+        else:
+            use_backup = False
+
+        if use_backup:
+            for path in (header_file_path, kunit_c_file_path):
+                if path.exists():
+                    try:
+                        path.rename(path.with_suffix(path.suffix + ".bak"))
+                    except OSError as e:
+                        raise KUnitError(f"Error backing up file {path}: {e}") from e
+
+        header_content = self.__fill_kunit_h(struct_name, prototypes)
+        try:
+            with open(header_file_path, 'w') as f:
+                f.write(header_content)
+            print(f"Successfully created KUnit header file: {header_file_path}")
+        except OSError as e:
+            raise KUnitError(f"Error writing to file {header_file_path}: {e}") from e
+
+        kunit_c_content = self.__fill_kunit_c(struct_name)
+        try:
+            with open(kunit_c_file_path, 'w') as f:
+                f.write(kunit_c_content)
+            print(f"Successfully created KUnit C file: {kunit_c_file_path}")
+        except OSError as e:
+            raise KUnitError(f"Error writing to file {kunit_c_file_path}: {e}") from e
diff --git a/tools/verification/rvgen/rvgen/templates/kunit.c b/tools/verification/rvgen/rvgen/templates/kunit.c
new file mode 100644
index 000000000000..d29bbf2ea5c6
--- /dev/null
+++ b/tools/verification/rvgen/rvgen/templates/kunit.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/rv.h>
+#include <rv/kunit.h>
+/*
+ * XXX: include required headers, e.g.,
+ * #include <linux/sched.h>
+ */
+#include "%%MODEL_NAME%%_kunit.h"
+
+#if IS_ENABLED(CONFIG_RV_MON_%%MODEL_NAME_UP%%)
+
+static void rv_test_%%MODEL_NAME%%(struct kunit *test)
+{
+	struct rv_kunit_ctx *ctx = test->priv;
+
+	prepare_test(test, &%%STRUCT_NAME%%.mon);
+
+	/*
+	 * XXX: write the test here
+	 * e.g.
+	 * RV_KUNIT_EXPECT_REACTION_HERE(test, ctx)
+	 *	%%STRUCT_NAME%%.handle_event(args);
+	 */
+}
+
+#else
+#define rv_test_%%MODEL_NAME%% rv_test_stub
+#endif
-- 
2.55.0