diff --git a/lib/test_printf.c b/lib/test_printf.c
index 53527ea..5d94cbf 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Test cases for printf facility.
  */
@@ -9,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/printk.h>
 #include <linux/random.h>
+#include <linux/rtc.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 
@@ -20,6 +22,8 @@
 #include <linux/gfp.h>
 #include <linux/mm.h>
 
+#include "../tools/testing/selftests/kselftest_module.h"
+
 #define BUF_SIZE 256
 #define PAD_SIZE 16
 #define FILL_CHAR '$'
@@ -238,6 +242,7 @@
 #define PTR ((void *)0x456789ab)
 #define PTR_STR "456789ab"
 #define PTR_VAL_NO_CRNG "(ptrval)"
+#define ZEROS ""
 
 static int __init
 plain_format(void)
@@ -249,12 +254,11 @@
 #endif	/* BITS_PER_LONG == 64 */
 
 static int __init
-plain_hash(void)
+plain_hash_to_buffer(const void *p, char *buf, size_t len)
 {
-	char buf[PLAIN_BUF_SIZE];
 	int nchars;
 
-	nchars = snprintf(buf, PLAIN_BUF_SIZE, "%p", PTR);
+	nchars = snprintf(buf, len, "%p", p);
 
 	if (nchars != PTR_WIDTH)
 		return -1;
@@ -265,6 +269,19 @@
 		return 0;
 	}
 
+	return 0;
+}
+
+static int __init
+plain_hash(void)
+{
+	char buf[PLAIN_BUF_SIZE];
+	int ret;
+
+	ret = plain_hash_to_buffer(PTR, buf, PLAIN_BUF_SIZE);
+	if (ret)
+		return ret;
+
 	if (strncmp(buf, PTR_STR, PTR_WIDTH) == 0)
 		return -1;
 
@@ -295,6 +312,41 @@
 }
 
 static void __init
+test_hashed(const char *fmt, const void *p)
+{
+	char buf[PLAIN_BUF_SIZE];
+	int ret;
+
+	/*
+	 * No need to increase failed test counter since this is assumed
+	 * to be called after plain().
+	 */
+	ret = plain_hash_to_buffer(p, buf, PLAIN_BUF_SIZE);
+	if (ret)
+		return;
+
+	test(buf, fmt, p);
+}
+
+static void __init
+null_pointer(void)
+{
+	test_hashed("%p", NULL);
+	test(ZEROS "00000000", "%px", NULL);
+	test("(null)", "%pE", NULL);
+}
+
+#define PTR_INVALID ((void *)0x000000ab)
+
+static void __init
+invalid_pointer(void)
+{
+	test_hashed("%p", PTR_INVALID);
+	test(ZEROS "000000ab", "%px", PTR_INVALID);
+	test("(efault)", "%pE", PTR_INVALID);
+}
+
+static void __init
 symbol_ptr(void)
 {
 }
@@ -403,6 +455,11 @@
 	test("foo", "%pd", &test_dentry[0]);
 	test("foo", "%pd2", &test_dentry[0]);
 
+	test("(null)", "%pd", NULL);
+	test("(efault)", "%pd", PTR_INVALID);
+	test("(null)", "%pD", NULL);
+	test("(efault)", "%pD", PTR_INVALID);
+
 	test("romeo", "%pd", &test_dentry[3]);
 	test("alfa/romeo", "%pd2", &test_dentry[3]);
 	test("bravo/alfa/romeo", "%pd3", &test_dentry[3]);
@@ -419,6 +476,28 @@
 }
 
 static void __init
+struct_rtc_time(void)
+{
+	/* 1543210543 */
+	const struct rtc_time tm = {
+		.tm_sec = 43,
+		.tm_min = 35,
+		.tm_hour = 5,
+		.tm_mday = 26,
+		.tm_mon = 10,
+		.tm_year = 118,
+	};
+
+	test("(%ptR?)", "%pt", &tm);
+	test("2018-11-26T05:35:43", "%ptR", &tm);
+	test("0118-10-26T05:35:43", "%ptRr", &tm);
+	test("05:35:43|2018-11-26", "%ptRt|%ptRd", &tm, &tm);
+	test("05:35:43|0118-10-26", "%ptRtr|%ptRdr", &tm, &tm);
+	test("05:35:43|2018-11-26", "%ptRttr|%ptRdtr", &tm, &tm);
+	test("05:35:43 tr|2018-11-26 tr", "%ptRt tr|%ptRd tr", &tm, &tm);
+}
+
+static void __init
 struct_clk(void)
 {
 }
@@ -427,14 +506,14 @@
 large_bitmap(void)
 {
 	const int nbits = 1 << 16;
-	unsigned long *bits = kcalloc(BITS_TO_LONGS(nbits), sizeof(long), GFP_KERNEL);
+	unsigned long *bits = bitmap_zalloc(nbits, GFP_KERNEL);
 	if (!bits)
 		return;
 
 	bitmap_set(bits, 1, 20);
 	bitmap_set(bits, 60000, 15);
 	test("1-20,60000-60014", "%*pbl", nbits, bits);
-	kfree(bits);
+	bitmap_free(bits);
 }
 
 static void __init
@@ -518,6 +597,8 @@
 test_pointer(void)
 {
 	plain();
+	null_pointer();
+	invalid_pointer();
 	symbol_ptr();
 	kernel_ptr();
 	struct_resource();
@@ -529,18 +610,18 @@
 	uuid();
 	dentry();
 	struct_va_format();
+	struct_rtc_time();
 	struct_clk();
 	bitmap();
 	netdev_features();
 	flags();
 }
 
-static int __init
-test_printf_init(void)
+static void __init selftest(void)
 {
 	alloced_buffer = kmalloc(BUF_SIZE + 2*PAD_SIZE, GFP_KERNEL);
 	if (!alloced_buffer)
-		return -ENOMEM;
+		return;
 	test_buffer = alloced_buffer + PAD_SIZE;
 
 	test_basic();
@@ -549,16 +630,8 @@
 	test_pointer();
 
 	kfree(alloced_buffer);
-
-	if (failed_tests == 0)
-		pr_info("all %u tests passed\n", total_tests);
-	else
-		pr_warn("failed %u out of %u tests\n", failed_tests, total_tests);
-
-	return failed_tests ? -EINVAL : 0;
 }
 
-module_init(test_printf_init);
-
+KSTM_MODULE_LOADERS(test_printf);
 MODULE_AUTHOR("Rasmus Villemoes <linux@rasmusvillemoes.dk>");
 MODULE_LICENSE("GPL");