[RFC,v2,01/14] kunit: test: add KUnit test runner core

diff --git a/include/kunit/test.h b/include/kunit/test.h
new file mode 100644
index 0000000000000..e0b14b227ac44
--- /dev/null
+++ b/include/kunit/test.h
@@ -0,0 +1,165 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Base unit test (KUnit) API.
+ *
+ * Copyright (C) 2018, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+
+#ifndef _KUNIT_TEST_H
+#define _KUNIT_TEST_H
+
+#include <linux/types.h>
+#include <linux/slab.h>
+
+struct test;
+
+/**
+ * struct test_case - represents an individual test case.
+ * @run_case: the function representing the actual test case.
+ * @name: the name of the test case.
+ *
+ * A test case is a function with the signature, ``void (*)(struct test *)``
+ * that makes expectations (see TEST_EXPECT_TRUE()) about code under test. Each
+ * test case is associated with a &struct test_module and will be run after the
+ * module's init function and followed by the module's exit function.
+ *
+ * A test case should be static and should only be created with the TEST_CASE()
+ * macro; additionally, every array of test cases should be terminated with an
+ * empty test case.
+ *
+ * Example:
+ *
+ * .. code-block:: c
+ *
+ *	void add_test_basic(struct test *test)
+ *	{
+ *		TEST_EXPECT_EQ(test, 1, add(1, 0));
+ *		TEST_EXPECT_EQ(test, 2, add(1, 1));
+ *		TEST_EXPECT_EQ(test, 0, add(-1, 1));
+ *		TEST_EXPECT_EQ(test, INT_MAX, add(0, INT_MAX));
+ *		TEST_EXPECT_EQ(test, -1, add(INT_MAX, INT_MIN));
+ *	}
+ *
+ *	static struct test_case example_test_cases[] = {
+ *		TEST_CASE(add_test_basic),
+ *		{},
+ *	};
+ *
+ */
+struct test_case {
+	void (*run_case)(struct test *test);
+	const char name[256];
+
+	/* private: internal use only. */
+	bool success;
+};
+
+/**
+ * TEST_CASE - A helper for creating a &struct test_case
+ * @test_name: a reference to a test case function.
+ *
+ * Takes a symbol for a function representing a test case and creates a &struct
+ * test_case object from it. See the documentation for &struct test_case for an
+ * example on how to use it.
+ */
+#define TEST_CASE(test_name) { .run_case = test_name, .name = #test_name }
+
+/**
+ * struct test_module - describes a related collection of &struct test_case s.
+ * @name: the name of the test. Purely informational.
+ * @init: called before every test case.
+ * @exit: called after every test case.
+ * @test_cases: a null terminated array of test cases.
+ *
+ * A test_module is a collection of related &struct test_case s, such that
+ * @init is called before every test case and @exit is called after every test
+ * case, similar to the notion of a *test fixture* or a *test class* in other
+ * unit testing frameworks like JUnit or Googletest.
+ *
+ * Every &struct test_case must be associated with a test_module for KUnit to
+ * run it.
+ */
+struct test_module {
+	const char name[256];
+	int (*init)(struct test *test);
+	void (*exit)(struct test *test);
+	struct test_case *test_cases;
+};
+
+/**
+ * struct test - represents a running instance of a test.
+ * @priv: for user to store arbitrary data. Commonly used to pass data created
+ * in the init function (see &struct test_module).
+ *
+ * Used to store information about the current context under which the test is
+ * running. Most of this data is private and should only be accessed indirectly
+ * via public functions; the one exception is @priv which can be used by the
+ * test writer to store arbitrary data.
+ */
+struct test {
+	void *priv;
+
+	/* private: internal use only. */
+	const char *name; /* Read only after initialization! */
+	spinlock_t lock; /* Gaurds all mutable test state. */
+	bool success; /* Protected by lock. */
+	void (*vprintk)(const struct test *test,
+			const char *level,
+			struct va_format *vaf);
+};
+
+int test_init_test(struct test *test, const char *name);
+
+int test_run_tests(struct test_module *module);
+
+/**
+ * module_test() - used to register a &struct test_module with KUnit.
+ * @module: a statically allocated &struct test_module.
+ *
+ * Registers @module with the test framework. See &struct test_module for more
+ * information.
+ */
+#define module_test(module) \
+		static int module_test_init##module(void) \
+		{ \
+			return test_run_tests(&module); \
+		} \
+		late_initcall(module_test_init##module)
+
+void __printf(3, 4) test_printk(const char *level,
+				const struct test *test,
+				const char *fmt, ...);
+
+/**
+ * test_info() - Prints an INFO level message associated with the current test.
+ * @test: The test context object.
+ * @fmt: A printk() style format string.
+ *
+ * Prints an info level message associated with the test module being run. Takes
+ * a variable number of format parameters just like printk().
+ */
+#define test_info(test, fmt, ...) \
+		test_printk(KERN_INFO, test, fmt, ##__VA_ARGS__)
+
+/**
+ * test_warn() - Prints a WARN level message associated with the current test.
+ * @test: The test context object.
+ * @fmt: A printk() style format string.
+ *
+ * See test_info().
+ */
+#define test_warn(test, fmt, ...) \
+		test_printk(KERN_WARNING, test, fmt, ##__VA_ARGS__)
+
+/**
+ * test_err() - Prints an ERROR level message associated with the current test.
+ * @test: The test context object.
+ * @fmt: A printk() style format string.
+ *
+ * See test_info().
+ */
+#define test_err(test, fmt, ...) \
+		test_printk(KERN_ERR, test, fmt, ##__VA_ARGS__)
+
+#endif /* _KUNIT_TEST_H */
diff --git a/kunit/Kconfig b/kunit/Kconfig
new file mode 100644
index 0000000000000..49b44c4f6630a
--- /dev/null
+++ b/kunit/Kconfig
@@ -0,0 +1,17 @@ 
+#
+# KUnit base configuration
+#
+
+menu "KUnit support"
+
+config KUNIT
+	bool "Enable support for unit tests (KUnit)"
+	depends on UML
+	help
+	  Enables support for kernel unit tests (KUnit), a lightweight unit
+	  testing and mocking framework for the Linux kernel. These tests are
+	  able to be run locally on a developer's workstation without a VM or
+	  special hardware. For more information, please see
+	  Documentation/kunit/
+
+endmenu
diff --git a/kunit/Makefile b/kunit/Makefile
new file mode 100644
index 0000000000000..dd7a0299514b7
--- /dev/null
+++ b/kunit/Makefile
@@ -0,0 +1 @@ 
+obj-$(CONFIG_KUNIT)		+= test.o
diff --git a/kunit/test.c b/kunit/test.c
new file mode 100644
index 0000000000000..4732e5f0d7575
--- /dev/null
+++ b/kunit/test.c
@@ -0,0 +1,168 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Base unit test (KUnit) API.
+ *
+ * Copyright (C) 2018, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <os.h>
+#include <kunit/test.h>
+
+static bool test_get_success(struct test *test)
+{
+	unsigned long flags;
+	bool success;
+
+	spin_lock_irqsave(&test->lock, flags);
+	success = test->success;
+	spin_unlock_irqrestore(&test->lock, flags);
+
+	return success;
+}
+
+static void test_set_success(struct test *test, bool success)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&test->lock, flags);
+	test->success = success;
+	spin_unlock_irqrestore(&test->lock, flags);
+}
+
+static int test_vprintk_emit(const struct test *test,
+			     int level,
+			     const char *fmt,
+			     va_list args)
+{
+	return vprintk_emit(0, level, NULL, 0, fmt, args);
+}
+
+static int test_printk_emit(const struct test *test,
+			    int level,
+			    const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, fmt);
+	ret = test_vprintk_emit(test, level, fmt, args);
+	va_end(args);
+
+	return ret;
+}
+
+static void test_vprintk(const struct test *test,
+			 const char *level,
+			 struct va_format *vaf)
+{
+	test_printk_emit(test,
+			 level[1] - '0',
+			 "kunit %s: %pV", test->name, vaf);
+}
+
+int test_init_test(struct test *test, const char *name)
+{
+	spin_lock_init(&test->lock);
+	test->name = name;
+	test->vprintk = test_vprintk;
+
+	return 0;
+}
+
+/*
+ * Initializes and runs test case. Does not clean up or do post validations.
+ */
+static void test_run_case_internal(struct test *test,
+				   struct test_module *module,
+				   struct test_case *test_case)
+{
+	int ret;
+
+	if (module->init) {
+		ret = module->init(test);
+		if (ret) {
+			test_err(test, "failed to initialize: %d", ret);
+			test_set_success(test, false);
+			return;
+		}
+	}
+
+	test_case->run_case(test);
+}
+
+/*
+ * Performs post validations and cleanup after a test case was run.
+ * XXX: Should ONLY BE CALLED AFTER test_run_case_internal!
+ */
+static void test_run_case_cleanup(struct test *test,
+				  struct test_module *module,
+				  struct test_case *test_case)
+{
+	if (module->exit)
+		module->exit(test);
+}
+
+/*
+ * Performs all logic to run a test case.
+ */
+static bool test_run_case(struct test *test,
+			  struct test_module *module,
+			  struct test_case *test_case)
+{
+	test_set_success(test, true);
+
+	test_run_case_internal(test, module, test_case);
+	test_run_case_cleanup(test, module, test_case);
+
+	return test_get_success(test);
+}
+
+int test_run_tests(struct test_module *module)
+{
+	bool all_passed = true, success;
+	struct test_case *test_case;
+	struct test test;
+	int ret;
+
+	ret = test_init_test(&test, module->name);
+	if (ret)
+		return ret;
+
+	for (test_case = module->test_cases; test_case->run_case; test_case++) {
+		success = test_run_case(&test, module, test_case);
+		if (!success)
+			all_passed = false;
+
+		test_info(&test,
+			  "%s %s",
+			  test_case->name,
+			  success ? "passed" : "failed");
+	}
+
+	if (all_passed)
+		test_info(&test, "all tests passed");
+	else
+		test_info(&test, "one or more tests failed");
+
+	return 0;
+}
+
+void test_printk(const char *level,
+		 const struct test *test,
+		 const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	test->vprintk(test, level, &vaf);
+
+	va_end(args);
+}