kunit: ubsan integration

Integrates UBSAN into the KUnit testing framework. It fails KUnit tests
whenever it reports undefined behavior.

When CONFIG_KUNIT=n, nothing is printed or even formatted, so this has
no behavioral impact outside of tests.

kunit_fail_current_test() effectively does a pr_err() as well, so
there's some slight duplication, but it also ensures an error is
recorded in the debugfs entry for the running KUnit test.

Print a shorter version of the message to make it less spammy.

Co-developed-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Uriel Guajardo <urielguajardo@google.com>
Signed-off-by: Daniel Latypov <dlatypov@google.com>

lib/ubsan.c

@@ -14,6 +14,7 @@
 #include <linux/types.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>
+#include <kunit/test-bug.h>
 
 #include "ubsan.h"
 
@@ -141,6 +142,8 @@ static void ubsan_prologue(struct source_location *loc, const char *reason)
 		"========================================\n");
 	pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
 		loc->line & LINE_MASK, loc->column & COLUMN_MASK);
+
+	kunit_fail_current_test("%s in %s", reason, loc->file_name);
 }
 
 static void ubsan_epilogue(void)