Merge tag 'linux-kselftest-kunit-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull more Kunit updates from Shuah Khan:

 - add Kunit to kernel_init() and remove KUnit from init calls entirely.

   This addresses the concern that Kunit would not work correctly during
   late init phase.

 - add a linker section where KUnit can put references to its test
   suites.

   This is the first step in transitioning to dispatching all KUnit
   tests from a centralized executor rather than having each as its own
   separate late_initcall.

 - add a centralized executor to dispatch tests rather than relying on
   late_initcall to schedule each test suite separately. Centralized
   execution is for built-in tests only; modules will execute tests when
   loaded.

 - convert bitfield test to use KUnit framework

 - Documentation updates for naming guidelines and how
   kunit_test_suite() works.

 - add test plan to KUnit TAP format

* tag 'linux-kselftest-kunit-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  lib: kunit: Fix compilation test when using TEST_BIT_FIELD_COMPILE
  lib: kunit: add bitfield test conversion to KUnit
  Documentation: kunit: add a brief blurb about kunit_test_suite
  kunit: test: add test plan to KUnit TAP format
  init: main: add KUnit to kernel init
  kunit: test: create a single centralized executor for all tests
  vmlinux.lds.h: add linker section for KUnit test suites
  Documentation: kunit: Add naming guidelines

2 files changed, 63 insertions, 23 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index e1843976754a..cd14444bf600 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -734,7 +734,8 @@
 	THERMAL_TABLE(governor)						\
 	EARLYCON_TABLE()						\
 	LSM_TABLE()							\
-	EARLY_LSM_TABLE()
+	EARLY_LSM_TABLE()						\
+	KUNIT_TABLE()
 
 #define INIT_TEXT							\
 	*(.init.text .init.text.*)					\
@@ -932,6 +933,13 @@
 		KEEP(*(.con_initcall.init))				\
 		__con_initcall_end = .;
 
+/* Alignment must be consistent with (kunit_suite *) in include/kunit/test.h */
+#define KUNIT_TABLE()							\
+		. = ALIGN(8);						\
+		__kunit_suites_start = .;				\
+		KEEP(*(.kunit_test_suites))				\
+		__kunit_suites_end = .;
+
 #ifdef CONFIG_BLK_DEV_INITRD
 #define INIT_RAM_FS							\
 	. = ALIGN(4);							\
diff --git a/include/kunit/test.h b/include/kunit/test.h
index 037de35ae0ff..a423fffefea0 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -239,10 +239,19 @@ size_t kunit_suite_num_test_cases(struct kunit_suite *suite);
 unsigned int kunit_test_case_num(struct kunit_suite *suite,
 				 struct kunit_case *test_case);
 
-int __kunit_test_suites_init(struct kunit_suite **suites);
+int __kunit_test_suites_init(struct kunit_suite * const * const suites);
 
 void __kunit_test_suites_exit(struct kunit_suite **suites);
 
+#if IS_BUILTIN(CONFIG_KUNIT)
+int kunit_run_all_tests(void);
+#else
+static inline int kunit_run_all_tests(void)
+{
+	return 0;
+}
+#endif /* IS_BUILTIN(CONFIG_KUNIT) */
+
 /**
  * kunit_test_suites() - used to register one or more &struct kunit_suite
  *			 with KUnit.
@@ -252,34 +261,57 @@ void __kunit_test_suites_exit(struct kunit_suite **suites);
  * Registers @suites_list with the test framework. See &struct kunit_suite for
  * more information.
  *
- * When builtin, KUnit tests are all run as late_initcalls; this means
- * that they cannot test anything where tests must run at a different init
- * phase. One significant restriction resulting from this is that KUnit
- * cannot reliably test anything that is initialize in the late_init phase;
- * another is that KUnit is useless to test things that need to be run in
- * an earlier init phase.
- *
- * An alternative is to build the tests as a module.  Because modules
- * do not support multiple late_initcall()s, we need to initialize an
- * array of suites for a module.
- *
- * TODO(brendanhiggins@google.com): Don't run all KUnit tests as
- * late_initcalls.  I have some future work planned to dispatch all KUnit
- * tests from the same place, and at the very least to do so after
- * everything else is definitely initialized.
+ * If a test suite is built-in, module_init() gets translated into
+ * an initcall which we don't want as the idea is that for builtins
+ * the executor will manage execution.  So ensure we do not define
+ * module_{init|exit} functions for the builtin case when registering
+ * suites via kunit_test_suites() below.
  */
-#define kunit_test_suites(suites_list...)				\
-	static struct kunit_suite *suites[] = {suites_list, NULL};	\
-	static int kunit_test_suites_init(void)				\
+#ifdef MODULE
+#define kunit_test_suites_for_module(__suites)				\
+	static int __init kunit_test_suites_init(void)			\
 	{								\
-		return __kunit_test_suites_init(suites);		\
+		return __kunit_test_suites_init(__suites);		\
 	}								\
-	late_initcall(kunit_test_suites_init);				\
+	module_init(kunit_test_suites_init);				\
+									\
 	static void __exit kunit_test_suites_exit(void)			\
 	{								\
-		return __kunit_test_suites_exit(suites);		\
+		return __kunit_test_suites_exit(__suites);		\
 	}								\
 	module_exit(kunit_test_suites_exit)
+#else
+#define kunit_test_suites_for_module(__suites)
+#endif /* MODULE */
+
+#define __kunit_test_suites(unique_array, unique_suites, ...)		       \
+	static struct kunit_suite *unique_array[] = { __VA_ARGS__, NULL };     \
+	kunit_test_suites_for_module(unique_array);			       \
+	static struct kunit_suite **unique_suites			       \
+	__used __section(.kunit_test_suites) = unique_array
+
+/**
+ * kunit_test_suites() - used to register one or more &struct kunit_suite
+ *			 with KUnit.
+ *
+ * @suites: a statically allocated list of &struct kunit_suite.
+ *
+ * Registers @suites with the test framework. See &struct kunit_suite for
+ * more information.
+ *
+ * When builtin,  KUnit tests are all run via executor; this is done
+ * by placing the array of struct kunit_suite * in the .kunit_test_suites
+ * ELF section.
+ *
+ * An alternative is to build the tests as a module.  Because modules do not
+ * support multiple initcall()s, we need to initialize an array of suites for a
+ * module.
+ *
+ */
+#define kunit_test_suites(...)						\
+	__kunit_test_suites(__UNIQUE_ID(array),				\
+			    __UNIQUE_ID(suites),			\
+			    __VA_ARGS__)
 
 #define kunit_test_suite(suite)	kunit_test_suites(&suite)