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From:   Vitor Massaru Iha <vitor@massaru.org>
To:     kunit-dev@googlegroups.com, skhan@linuxfoundation.org
Cc:     linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
        brendanhiggins@google.com,
        linux-kernel-mentees@lists.linuxfoundation.org,
        keescook@chromium.org, linux@rasmusvillemoes.dk
Subject: [PATCH] lib: kunit_test_overflow: add KUnit test of check_*_overflow functions
Date:   Thu, 11 Jun 2020 18:55:01 -0300
Message-Id: <20200611215501.213058-1-vitor@massaru.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This adds the convertion of the runtime tests of check_*_overflow fuctions,
from `lib/test_overflow.c`to KUnit tests.

The log similar to the one seen in dmesg running test_overflow can be
seen in `test.log`.

Signed-off-by: Vitor Massaru Iha <vitor@massaru.org>
---
 lib/Kconfig.debug         |  17 ++
 lib/Makefile              |   1 +
 lib/kunit_overflow_test.c | 590 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 608 insertions(+)
 create mode 100644 lib/kunit_overflow_test.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1f4ab7a2bdee..72fcfe1f24a4 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2075,6 +2075,23 @@ config SYSCTL_KUNIT_TEST
 
 	  If unsure, say N.
 
+config OVERFLOW_KUNIT_TEST
+	tristate "KUnit test for overflow" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the overflow KUnit tests.
+
+	  KUnit tests run during boot and output the results to the debug log
+	  in TAP format (http://testanything.org/). Only useful for kernel devs
+	  running KUnit test harness and are not for inclusion into a production
+	  build.
+
+	  For more information on KUnit and unit tests in general please refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
 config LIST_KUNIT_TEST
 	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
 	depends on KUNIT
diff --git a/lib/Makefile b/lib/Makefile
index 685aee60de1d..a3290adc0019 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -309,3 +309,4 @@ obj-$(CONFIG_OBJAGG) += objagg.o
 
 # KUnit tests
 obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
+obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += kunit_overflow_test.o
diff --git a/lib/kunit_overflow_test.c b/lib/kunit_overflow_test.c
new file mode 100644
index 000000000000..c3eb8f0d3d50
--- /dev/null
+++ b/lib/kunit_overflow_test.c
@@ -0,0 +1,590 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  This code is the conversion of the overflow test in runtime to KUnit tests.
+ */
+
+/*
+ * Test cases for arithmetic overflow checks.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <kunit/test.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/overflow.h>
+#include <linux/vmalloc.h>
+
+#define DEFINE_TEST_ARRAY(t)			\
+	static const struct test_ ## t {	\
+		t a, b;				\
+		t sum, diff, prod;		\
+		bool s_of, d_of, p_of;		\
+	} t ## _tests[]
+
+DEFINE_TEST_ARRAY(u8) = {
+	{0, 0, 0, 0, 0, false, false, false},
+	{1, 1, 2, 0, 1, false, false, false},
+	{0, 1, 1, U8_MAX, 0, false, true, false},
+	{1, 0, 1, 1, 0, false, false, false},
+	{0, U8_MAX, U8_MAX, 1, 0, false, true, false},
+	{U8_MAX, 0, U8_MAX, U8_MAX, 0, false, false, false},
+	{1, U8_MAX, 0, 2, U8_MAX, true, true, false},
+	{U8_MAX, 1, 0, U8_MAX-1, U8_MAX, true, false, false},
+	{U8_MAX, U8_MAX, U8_MAX-1, 0, 1, true, false, true},
+
+	{U8_MAX, U8_MAX-1, U8_MAX-2, 1, 2, true, false, true},
+	{U8_MAX-1, U8_MAX, U8_MAX-2, U8_MAX, 2, true, true, true},
+
+	{1U << 3, 1U << 3, 1U << 4, 0, 1U << 6, false, false, false},
+	{1U << 4, 1U << 4, 1U << 5, 0, 0, false, false, true},
+	{1U << 4, 1U << 3, 3*(1U << 3), 1U << 3, 1U << 7, false, false, false},
+	{1U << 7, 1U << 7, 0, 0, 0, true, false, true},
+
+	{48, 32, 80, 16, 0, false, false, true},
+	{128, 128, 0, 0, 0, true, false, true},
+	{123, 234, 101, 145, 110, true, true, true},
+};
+
+DEFINE_TEST_ARRAY(u16) = {
+	{0, 0, 0, 0, 0, false, false, false},
+	{1, 1, 2, 0, 1, false, false, false},
+	{0, 1, 1, U16_MAX, 0, false, true, false},
+	{1, 0, 1, 1, 0, false, false, false},
+	{0, U16_MAX, U16_MAX, 1, 0, false, true, false},
+	{U16_MAX, 0, U16_MAX, U16_MAX, 0, false, false, false},
+	{1, U16_MAX, 0, 2, U16_MAX, true, true, false},
+	{U16_MAX, 1, 0, U16_MAX-1, U16_MAX, true, false, false},
+	{U16_MAX, U16_MAX, U16_MAX-1, 0, 1, true, false, true},
+
+	{U16_MAX, U16_MAX-1, U16_MAX-2, 1, 2, true, false, true},
+	{U16_MAX-1, U16_MAX, U16_MAX-2, U16_MAX, 2, true, true, true},
+
+	{1U << 7, 1U << 7, 1U << 8, 0, 1U << 14, false, false, false},
+	{1U << 8, 1U << 8, 1U << 9, 0, 0, false, false, true},
+	{1U << 8, 1U << 7, 3*(1U << 7), 1U << 7, 1U << 15, false, false, false},
+	{1U << 15, 1U << 15, 0, 0, 0, true, false, true},
+
+	{123, 234, 357, 65425, 28782, false, true, false},
+	{1234, 2345, 3579, 64425, 10146, false, true, true},
+};
+
+DEFINE_TEST_ARRAY(u32) = {
+	{0, 0, 0, 0, 0, false, false, false},
+	{1, 1, 2, 0, 1, false, false, false},
+	{0, 1, 1, U32_MAX, 0, false, true, false},
+	{1, 0, 1, 1, 0, false, false, false},
+	{0, U32_MAX, U32_MAX, 1, 0, false, true, false},
+	{U32_MAX, 0, U32_MAX, U32_MAX, 0, false, false, false},
+	{1, U32_MAX, 0, 2, U32_MAX, true, true, false},
+	{U32_MAX, 1, 0, U32_MAX-1, U32_MAX, true, false, false},
+	{U32_MAX, U32_MAX, U32_MAX-1, 0, 1, true, false, true},
+
+	{U32_MAX, U32_MAX-1, U32_MAX-2, 1, 2, true, false, true},
+	{U32_MAX-1, U32_MAX, U32_MAX-2, U32_MAX, 2, true, true, true},
+
+	{1U << 15, 1U << 15, 1U << 16, 0, 1U << 30, false, false, false},
+	{1U << 16, 1U << 16, 1U << 17, 0, 0, false, false, true},
+	{1U << 16, 1U << 15, 3*(1U << 15), 1U << 15, 1U << 31, false, false, false},
+	{1U << 31, 1U << 31, 0, 0, 0, true, false, true},
+
+	{-2U, 1U, -1U, -3U, -2U, false, false, false},
+	{-4U, 5U, 1U, -9U, -20U, true, false, true},
+};
+
+DEFINE_TEST_ARRAY(u64) = {
+	{0, 0, 0, 0, 0, false, false, false},
+	{1, 1, 2, 0, 1, false, false, false},
+	{0, 1, 1, U64_MAX, 0, false, true, false},
+	{1, 0, 1, 1, 0, false, false, false},
+	{0, U64_MAX, U64_MAX, 1, 0, false, true, false},
+	{U64_MAX, 0, U64_MAX, U64_MAX, 0, false, false, false},
+	{1, U64_MAX, 0, 2, U64_MAX, true, true, false},
+	{U64_MAX, 1, 0, U64_MAX-1, U64_MAX, true, false, false},
+	{U64_MAX, U64_MAX, U64_MAX-1, 0, 1, true, false, true},
+
+	{U64_MAX, U64_MAX-1, U64_MAX-2, 1, 2, true, false, true},
+	{U64_MAX-1, U64_MAX, U64_MAX-2, U64_MAX, 2, true, true, true},
+
+	{1ULL << 31, 1ULL << 31, 1ULL << 32, 0, 1ULL << 62, false, false, false},
+	{1ULL << 32, 1ULL << 32, 1ULL << 33, 0, 0, false, false, true},
+	{1ULL << 32, 1ULL << 31, 3*(1ULL << 31), 1ULL << 31, 1ULL << 63, false, false, false},
+	{1ULL << 63, 1ULL << 63, 0, 0, 0, true, false, true},
+	{1000000000ULL /* 10^9 */, 10000000000ULL /* 10^10 */,
+	 11000000000ULL, 18446744064709551616ULL, 10000000000000000000ULL,
+	 false, true, false},
+	{-15ULL, 10ULL, -5ULL, -25ULL, -150ULL, false, false, true},
+};
+
+DEFINE_TEST_ARRAY(s8) = {
+	{0, 0, 0, 0, 0, false, false, false},
+
+	{0, S8_MAX, S8_MAX, -S8_MAX, 0, false, false, false},
+	{S8_MAX, 0, S8_MAX, S8_MAX, 0, false, false, false},
+	{0, S8_MIN, S8_MIN, S8_MIN, 0, false, true, false},
+	{S8_MIN, 0, S8_MIN, S8_MIN, 0, false, false, false},
+
+	{-1, S8_MIN, S8_MAX, S8_MAX, S8_MIN, true, false, true},
+	{S8_MIN, -1, S8_MAX, -S8_MAX, S8_MIN, true, false, true},
+	{-1, S8_MAX, S8_MAX-1, S8_MIN, -S8_MAX, false, false, false},
+	{S8_MAX, -1, S8_MAX-1, S8_MIN, -S8_MAX, false, true, false},
+	{-1, -S8_MAX, S8_MIN, S8_MAX-1, S8_MAX, false, false, false},
+	{-S8_MAX, -1, S8_MIN, S8_MIN+2, S8_MAX, false, false, false},
+
+	{1, S8_MIN, -S8_MAX, -S8_MAX, S8_MIN, false, true, false},
+	{S8_MIN, 1, -S8_MAX, S8_MAX, S8_MIN, false, true, false},
+	{1, S8_MAX, S8_MIN, S8_MIN+2, S8_MAX, true, false, false},
+	{S8_MAX, 1, S8_MIN, S8_MAX-1, S8_MAX, true, false, false},
+
+	{S8_MIN, S8_MIN, 0, 0, 0, true, false, true},
+	{S8_MAX, S8_MAX, -2, 0, 1, true, false, true},
+
+	{-4, -32, -36, 28, -128, false, false, true},
+	{-4, 32, 28, -36, -128, false, false, false},
+};
+
+DEFINE_TEST_ARRAY(s16) = {
+	{0, 0, 0, 0, 0, false, false, false},
+
+	{0, S16_MAX, S16_MAX, -S16_MAX, 0, false, false, false},
+	{S16_MAX, 0, S16_MAX, S16_MAX, 0, false, false, false},
+	{0, S16_MIN, S16_MIN, S16_MIN, 0, false, true, false},
+	{S16_MIN, 0, S16_MIN, S16_MIN, 0, false, false, false},
+
+	{-1, S16_MIN, S16_MAX, S16_MAX, S16_MIN, true, false, true},
+	{S16_MIN, -1, S16_MAX, -S16_MAX, S16_MIN, true, false, true},
+	{-1, S16_MAX, S16_MAX-1, S16_MIN, -S16_MAX, false, false, false},
+	{S16_MAX, -1, S16_MAX-1, S16_MIN, -S16_MAX, false, true, false},
+	{-1, -S16_MAX, S16_MIN, S16_MAX-1, S16_MAX, false, false, false},
+	{-S16_MAX, -1, S16_MIN, S16_MIN+2, S16_MAX, false, false, false},
+
+	{1, S16_MIN, -S16_MAX, -S16_MAX, S16_MIN, false, true, false},
+	{S16_MIN, 1, -S16_MAX, S16_MAX, S16_MIN, false, true, false},
+	{1, S16_MAX, S16_MIN, S16_MIN+2, S16_MAX, true, false, false},
+	{S16_MAX, 1, S16_MIN, S16_MAX-1, S16_MAX, true, false, false},
+
+	{S16_MIN, S16_MIN, 0, 0, 0, true, false, true},
+	{S16_MAX, S16_MAX, -2, 0, 1, true, false, true},
+};
+
+DEFINE_TEST_ARRAY(s32) = {
+	{0, 0, 0, 0, 0, false, false, false},
+
+	{0, S32_MAX, S32_MAX, -S32_MAX, 0, false, false, false},
+	{S32_MAX, 0, S32_MAX, S32_MAX, 0, false, false, false},
+	{0, S32_MIN, S32_MIN, S32_MIN, 0, false, true, false},
+	{S32_MIN, 0, S32_MIN, S32_MIN, 0, false, false, false},
+
+	{-1, S32_MIN, S32_MAX, S32_MAX, S32_MIN, true, false, true},
+	{S32_MIN, -1, S32_MAX, -S32_MAX, S32_MIN, true, false, true},
+	{-1, S32_MAX, S32_MAX-1, S32_MIN, -S32_MAX, false, false, false},
+	{S32_MAX, -1, S32_MAX-1, S32_MIN, -S32_MAX, false, true, false},
+	{-1, -S32_MAX, S32_MIN, S32_MAX-1, S32_MAX, false, false, false},
+	{-S32_MAX, -1, S32_MIN, S32_MIN+2, S32_MAX, false, false, false},
+
+	{1, S32_MIN, -S32_MAX, -S32_MAX, S32_MIN, false, true, false},
+	{S32_MIN, 1, -S32_MAX, S32_MAX, S32_MIN, false, true, false},
+	{1, S32_MAX, S32_MIN, S32_MIN+2, S32_MAX, true, false, false},
+	{S32_MAX, 1, S32_MIN, S32_MAX-1, S32_MAX, true, false, false},
+
+	{S32_MIN, S32_MIN, 0, 0, 0, true, false, true},
+	{S32_MAX, S32_MAX, -2, 0, 1, true, false, true},
+};
+
+DEFINE_TEST_ARRAY(s64) = {
+	{0, 0, 0, 0, 0, false, false, false},
+
+	{0, S64_MAX, S64_MAX, -S64_MAX, 0, false, false, false},
+	{S64_MAX, 0, S64_MAX, S64_MAX, 0, false, false, false},
+	{0, S64_MIN, S64_MIN, S64_MIN, 0, false, true, false},
+	{S64_MIN, 0, S64_MIN, S64_MIN, 0, false, false, false},
+
+	{-1, S64_MIN, S64_MAX, S64_MAX, S64_MIN, true, false, true},
+	{S64_MIN, -1, S64_MAX, -S64_MAX, S64_MIN, true, false, true},
+	{-1, S64_MAX, S64_MAX-1, S64_MIN, -S64_MAX, false, false, false},
+	{S64_MAX, -1, S64_MAX-1, S64_MIN, -S64_MAX, false, true, false},
+	{-1, -S64_MAX, S64_MIN, S64_MAX-1, S64_MAX, false, false, false},
+	{-S64_MAX, -1, S64_MIN, S64_MIN+2, S64_MAX, false, false, false},
+
+	{1, S64_MIN, -S64_MAX, -S64_MAX, S64_MIN, false, true, false},
+	{S64_MIN, 1, -S64_MAX, S64_MAX, S64_MIN, false, true, false},
+	{1, S64_MAX, S64_MIN, S64_MIN+2, S64_MAX, true, false, false},
+	{S64_MAX, 1, S64_MIN, S64_MAX-1, S64_MAX, true, false, false},
+
+	{S64_MIN, S64_MIN, 0, 0, 0, true, false, true},
+	{S64_MAX, S64_MAX, -2, 0, 1, true, false, true},
+
+	{-1, -1, -2, 0, 1, false, false, false},
+	{-1, -128, -129, 127, 128, false, false, false},
+	{-128, -1, -129, -127, 128, false, false, false},
+	{0, -S64_MAX, -S64_MAX, S64_MAX, 0, false, false, false},
+};
+
+#define check_one_op(test, t, fmt, op, sym, a, b, r, of) do {		\
+	t _r;								\
+	bool _of;							\
+									\
+	_of = check_ ## op ## _overflow(a, b, &_r);			\
+	if (_of != of) {						\
+		KUNIT_FAIL(test, "Expected "fmt" "sym" "fmt		\
+			" to%s overflow (type %s)\n",			\
+			a, b, of ? "" : " not", #t);			\
+	}								\
+	if (_r != r) {							\
+		KUNIT_FAIL(test, "Expected "fmt" "sym" "fmt" == "	\
+			fmt", got "fmt" (type %s)\n",			\
+			a, b, r, _r, #t);				\
+	}								\
+} while (0)
+
+#define DEFINE_TEST_FUNC(test, t, fmt)						\
+static void do_test_ ## t(struct kunit *test, const struct test_ ## t *p)	\
+{										\
+	check_one_op(test, t, fmt, add, "+", p->a, p->b, p->sum, p->s_of);	\
+	check_one_op(test, t, fmt, add, "+", p->b, p->a, p->sum, p->s_of);	\
+	check_one_op(test, t, fmt, sub, "-", p->a, p->b, p->diff, p->d_of);	\
+	check_one_op(test, t, fmt, mul, "*", p->a, p->b, p->prod, p->p_of);	\
+	check_one_op(test, t, fmt, mul, "*", p->b, p->a, p->prod, p->p_of);	\
+}										\
+										\
+static void  test_ ## t ## _overflow(struct kunit *test)			\
+{										\
+	unsigned i;								\
+										\
+	kunit_warn(test, "%-3s: %zu arithmetic tests\n", #t,			\
+		ARRAY_SIZE(t ## _tests));					\
+	for (i = 0; i < ARRAY_SIZE(t ## _tests); ++i)				\
+		do_test_ ## t(test, &t ## _tests[i]);				\
+}
+
+DEFINE_TEST_FUNC(test, u8, "%d");
+DEFINE_TEST_FUNC(test, s8, "%d");
+DEFINE_TEST_FUNC(test, u16, "%d");
+DEFINE_TEST_FUNC(test, s16, "%d");
+DEFINE_TEST_FUNC(test, u32, "%u");
+DEFINE_TEST_FUNC(test, s32, "%d");
+#if BITS_PER_LONG == 64
+DEFINE_TEST_FUNC(test, u64, "%llu");
+DEFINE_TEST_FUNC(test, s64, "%lld");
+#endif
+
+static void  overflow_calculation_test(struct kunit *test)
+{
+
+	test_u8_overflow(test);
+	test_s8_overflow(test);
+	test_s8_overflow(test);
+	test_u16_overflow(test);
+	test_s16_overflow(test);
+	test_u32_overflow(test);
+	test_s32_overflow(test);
+#if BITS_PER_LONG == 64
+	test_u64_overflow(test);
+	test_s64_overflow(test);
+#endif
+}
+
+static void overflow_shift_test(struct kunit *test)
+{
+/* Args are: value, shift, type, expected result, overflow expected */
+#define TEST_ONE_SHIFT(a, s, t, expect, of) ({					\
+	int __failed = 0;							\
+	typeof(a) __a = (a);							\
+	typeof(s) __s = (s);							\
+	t __e = (expect);							\
+	t __d;									\
+	bool __of = check_shl_overflow(__a, __s, &__d);				\
+	if (__of != of) {							\
+		KUNIT_FAIL(test, "Expected (%s)(%s << %s) to%s overflow\n",	\
+			#t, #a, #s, of ? "" : " not");				\
+		__failed = 1;							\
+	} else if (!__of && __d != __e) {					\
+		KUNIT_FAIL(test, "Expected (%s)(%s << %s) == %s\n",		\
+			#t, #a, #s, #expect);					\
+		if ((t)-1 < 0)							\
+			KUNIT_FAIL(test, "got %lld\n", (s64)__d);		\
+		else								\
+			KUNIT_FAIL(test, "got %llu\n", (u64)__d);		\
+		__failed = 1;							\
+	}									\
+	if (!__failed)								\
+		kunit_info(test, "ok: (%s)(%s << %s) == %s\n", #t, #a, #s,	\
+			of ? "overflow" : #expect);				\
+	__failed;								\
+})
+
+	/* Sane shifts. */
+	TEST_ONE_SHIFT(1, 0, u8, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 4, u8, 1 << 4, false);
+	TEST_ONE_SHIFT(1, 7, u8, 1 << 7, false);
+	TEST_ONE_SHIFT(0xF, 4, u8, 0xF << 4, false);
+	TEST_ONE_SHIFT(1, 0, u16, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 10, u16, 1 << 10, false);
+	TEST_ONE_SHIFT(1, 15, u16, 1 << 15, false);
+	TEST_ONE_SHIFT(0xFF, 8, u16, 0xFF << 8, false);
+	TEST_ONE_SHIFT(1, 0, int, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 16, int, 1 << 16, false);
+	TEST_ONE_SHIFT(1, 30, int, 1 << 30, false);
+	TEST_ONE_SHIFT(1, 0, s32, 1 << 0, false);
+	TEST_ONE_SHIFT(1, 16, s32, 1 << 16, false);
+	TEST_ONE_SHIFT(1, 30, s32, 1 << 30, false);
+	TEST_ONE_SHIFT(1, 0, unsigned int, 1U << 0, false);
+	TEST_ONE_SHIFT(1, 20, unsigned int, 1U << 20, false);
+	TEST_ONE_SHIFT(1, 31, unsigned int, 1U << 31, false);
+	TEST_ONE_SHIFT(0xFFFFU, 16, unsigned int, 0xFFFFU << 16, false);
+	TEST_ONE_SHIFT(1, 0, u32, 1U << 0, false);
+	TEST_ONE_SHIFT(1, 20, u32, 1U << 20, false);
+	TEST_ONE_SHIFT(1, 31, u32, 1U << 31, false);
+	TEST_ONE_SHIFT(0xFFFFU, 16, u32, 0xFFFFU << 16, false);
+	TEST_ONE_SHIFT(1, 0, u64, 1ULL << 0, false);
+	TEST_ONE_SHIFT(1, 40, u64, 1ULL << 40, false);
+	TEST_ONE_SHIFT(1, 63, u64, 1ULL << 63, false);
+	TEST_ONE_SHIFT(0xFFFFFFFFULL, 32, u64,
+			      0xFFFFFFFFULL << 32, false);
+
+	/* Sane shift: start and end with 0, without a too-wide shift. */
+	TEST_ONE_SHIFT(0, 7, u8, 0, false);
+	TEST_ONE_SHIFT(0, 15, u16, 0, false);
+	TEST_ONE_SHIFT(0, 31, unsigned int, 0, false);
+	TEST_ONE_SHIFT(0, 31, u32, 0, false);
+	TEST_ONE_SHIFT(0, 63, u64, 0, false);
+
+	/* Sane shift: start and end with 0, without reaching signed bit. */
+	TEST_ONE_SHIFT(0, 6, s8, 0, false);
+	TEST_ONE_SHIFT(0, 14, s16, 0, false);
+	TEST_ONE_SHIFT(0, 30, int, 0, false);
+	TEST_ONE_SHIFT(0, 30, s32, 0, false);
+	TEST_ONE_SHIFT(0, 62, s64, 0, false);
+
+	/* Overflow: shifted the bit off the end. */
+	TEST_ONE_SHIFT(1, 8, u8, 0, true);
+	TEST_ONE_SHIFT(1, 16, u16, 0, true);
+	TEST_ONE_SHIFT(1, 32, unsigned int, 0, true);
+	TEST_ONE_SHIFT(1, 32, u32, 0, true);
+	TEST_ONE_SHIFT(1, 64, u64, 0, true);
+
+	/* Overflow: shifted into the signed bit. */
+	TEST_ONE_SHIFT(1, 7, s8, 0, true);
+	TEST_ONE_SHIFT(1, 15, s16, 0, true);
+	TEST_ONE_SHIFT(1, 31, int, 0, true);
+	TEST_ONE_SHIFT(1, 31, s32, 0, true);
+	TEST_ONE_SHIFT(1, 63, s64, 0, true);
+
+	/* Overflow: high bit falls off unsigned types. */
+	/* 10010110 */
+	TEST_ONE_SHIFT(150, 1, u8, 0, true);
+	/* 1000100010010110 */
+	TEST_ONE_SHIFT(34966, 1, u16, 0, true);
+	/* 10000100000010001000100010010110 */
+	TEST_ONE_SHIFT(2215151766U, 1, u32, 0, true);
+	TEST_ONE_SHIFT(2215151766U, 1, unsigned int, 0, true);
+	/* 1000001000010000010000000100000010000100000010001000100010010110 */
+	TEST_ONE_SHIFT(9372061470395238550ULL, 1, u64, 0, true);
+
+	/* Overflow: bit shifted into signed bit on signed types. */
+	/* 01001011 */
+	TEST_ONE_SHIFT(75, 1, s8, 0, true);
+	/* 0100010001001011 */
+	TEST_ONE_SHIFT(17483, 1, s16, 0, true);
+	/* 01000010000001000100010001001011 */
+	TEST_ONE_SHIFT(1107575883, 1, s32, 0, true);
+	TEST_ONE_SHIFT(1107575883, 1, int, 0, true);
+	/* 0100000100001000001000000010000001000010000001000100010001001011 */
+	TEST_ONE_SHIFT(4686030735197619275LL, 1, s64, 0, true);
+
+	/* Overflow: bit shifted past signed bit on signed types. */
+	/* 01001011 */
+	TEST_ONE_SHIFT(75, 2, s8, 0, true);
+	/* 0100010001001011 */
+	TEST_ONE_SHIFT(17483, 2, s16, 0, true);
+	/* 01000010000001000100010001001011 */
+	TEST_ONE_SHIFT(1107575883, 2, s32, 0, true);
+	TEST_ONE_SHIFT(1107575883, 2, int, 0, true);
+	/* 0100000100001000001000000010000001000010000001000100010001001011 */
+	TEST_ONE_SHIFT(4686030735197619275LL, 2, s64, 0, true);
+
+	/* Overflow: values larger than destination type. */
+	TEST_ONE_SHIFT(0x100, 0, u8, 0, true);
+	TEST_ONE_SHIFT(0xFF, 0, s8, 0, true);
+	TEST_ONE_SHIFT(0x10000U, 0, u16, 0, true);
+	TEST_ONE_SHIFT(0xFFFFU, 0, s16, 0, true);
+	TEST_ONE_SHIFT(0x100000000ULL, 0, u32, 0, true);
+	TEST_ONE_SHIFT(0x100000000ULL, 0, unsigned int, 0, true);
+	TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, s32, 0, true);
+	TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, int, 0, true);
+	TEST_ONE_SHIFT(0xFFFFFFFFFFFFFFFFULL, 0, s64, 0, true);
+
+	/* Nonsense: negative initial value. */
+	TEST_ONE_SHIFT(-1, 0, s8, 0, true);
+	TEST_ONE_SHIFT(-1, 0, u8, 0, true);
+	TEST_ONE_SHIFT(-5, 0, s16, 0, true);
+	TEST_ONE_SHIFT(-5, 0, u16, 0, true);
+	TEST_ONE_SHIFT(-10, 0, int, 0, true);
+	TEST_ONE_SHIFT(-10, 0, unsigned int, 0, true);
+	TEST_ONE_SHIFT(-100, 0, s32, 0, true);
+	TEST_ONE_SHIFT(-100, 0, u32, 0, true);
+	TEST_ONE_SHIFT(-10000, 0, s64, 0, true);
+	TEST_ONE_SHIFT(-10000, 0, u64, 0, true);
+
+	/* Nonsense: negative shift values. */
+	TEST_ONE_SHIFT(0, -5, s8, 0, true);
+	TEST_ONE_SHIFT(0, -5, u8, 0, true);
+	TEST_ONE_SHIFT(0, -10, s16, 0, true);
+	TEST_ONE_SHIFT(0, -10, u16, 0, true);
+	TEST_ONE_SHIFT(0, -15, int, 0, true);
+	TEST_ONE_SHIFT(0, -15, unsigned int, 0, true);
+	TEST_ONE_SHIFT(0, -20, s32, 0, true);
+	TEST_ONE_SHIFT(0, -20, u32, 0, true);
+	TEST_ONE_SHIFT(0, -30, s64, 0, true);
+	TEST_ONE_SHIFT(0, -30, u64, 0, true);
+
+	/* Overflow: shifted at or beyond entire type's bit width. */
+	TEST_ONE_SHIFT(0, 8, u8, 0, true);
+	TEST_ONE_SHIFT(0, 9, u8, 0, true);
+	TEST_ONE_SHIFT(0, 8, s8, 0, true);
+	TEST_ONE_SHIFT(0, 9, s8, 0, true);
+	TEST_ONE_SHIFT(0, 16, u16, 0, true);
+	TEST_ONE_SHIFT(0, 17, u16, 0, true);
+	TEST_ONE_SHIFT(0, 16, s16, 0, true);
+	TEST_ONE_SHIFT(0, 17, s16, 0, true);
+	TEST_ONE_SHIFT(0, 32, u32, 0, true);
+	TEST_ONE_SHIFT(0, 33, u32, 0, true);
+	TEST_ONE_SHIFT(0, 32, int, 0, true);
+	TEST_ONE_SHIFT(0, 33, int, 0, true);
+	TEST_ONE_SHIFT(0, 32, s32, 0, true);
+	TEST_ONE_SHIFT(0, 33, s32, 0, true);
+	TEST_ONE_SHIFT(0, 64, u64, 0, true);
+	TEST_ONE_SHIFT(0, 65, u64, 0, true);
+	TEST_ONE_SHIFT(0, 64, s64, 0, true);
+	TEST_ONE_SHIFT(0, 65, s64, 0, true);
+
+	/*
+	 * Corner case: for unsigned types, we fail when we've shifted
+	 * through the entire width of bits. For signed types, we might
+	 * want to match this behavior, but that would mean noticing if
+	 * we shift through all but the signed bit, and this is not
+	 * currently detected (but we'll notice an overflow into the
+	 * signed bit). So, for now, we will test this condition but
+	 * mark it as not expected to overflow.
+	 */
+	TEST_ONE_SHIFT(0, 7, s8, 0, false);
+	TEST_ONE_SHIFT(0, 15, s16, 0, false);
+	TEST_ONE_SHIFT(0, 31, int, 0, false);
+	TEST_ONE_SHIFT(0, 31, s32, 0, false);
+	TEST_ONE_SHIFT(0, 63, s64, 0, false);
+}
+
+/*
+ * Deal with the various forms of allocator arguments. See comments above
+ * the DEFINE_TEST_ALLOC() instances for mapping of the "bits".
+ */
+#define alloc_GFP		 (GFP_KERNEL | __GFP_NOWARN)
+#define alloc010(alloc, arg, sz) alloc(sz, alloc_GFP)
+#define alloc011(alloc, arg, sz) alloc(sz, alloc_GFP, NUMA_NO_NODE)
+#define alloc000(alloc, arg, sz) alloc(sz)
+#define alloc001(alloc, arg, sz) alloc(sz, NUMA_NO_NODE)
+#define alloc110(alloc, arg, sz) alloc(arg, sz, alloc_GFP)
+#define free0(free, arg, ptr)	 free(ptr)
+#define free1(free, arg, ptr)	 free(arg, ptr)
+
+/* Wrap around to 16K */
+#define TEST_SIZE		(5 * 4096)
+
+#define DEFINE_TEST_ALLOC(test, func, free_func, want_arg, want_gfp, want_node)	\
+static void test_ ## func (struct kunit *test, void *arg)			\
+{										\
+	volatile size_t a = TEST_SIZE;						\
+	volatile size_t b = (SIZE_MAX / TEST_SIZE) + 1;				\
+	void *ptr;								\
+										\
+	/* Tiny allocation test. */						\
+	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg, 1);	\
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, ptr);				\
+	if (!ptr) {								\
+		kunit_err(test, #func " failed regular allocation?!\n");	\
+	}									\
+	free ## want_arg (free_func, arg, ptr);					\
+										\
+	/* Wrapped allocation test. */						\
+	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg, a * b);	\
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, ptr);				\
+	if (!ptr) {								\
+		kunit_err(test, #func " unexpectedly failed bad wrapping?!\n");	\
+	}									\
+	free ## want_arg (free_func, arg, ptr);					\
+										\
+	/* Saturated allocation test. */					\
+	ptr = alloc ## want_arg ## want_gfp ## want_node (func, arg,		\
+						   array_size(a, b));		\
+	KUNIT_ASSERT_TRUE(test, IS_ERR_OR_NULL(ptr));				\
+	if (ptr) {								\
+		kunit_err(test, #func " missed saturation!\n");			\
+		free ## want_arg (free_func, arg, ptr);				\
+	}									\
+	kunit_info(test, #func " detected saturation\n");			\
+}
+
+/*
+ * Allocator uses a trailing node argument -------------------+  (e.g. kmalloc_node())
+ * Allocator uses the gfp_t argument ----------------------+  |  (e.g. kmalloc())
+ * Allocator uses a special leading argument -----------+  |  |  (e.g. devm_kmalloc())
+ *							|  |  |
+ */
+DEFINE_TEST_ALLOC(test, kmalloc,	kfree,		0, 1, 0);
+DEFINE_TEST_ALLOC(test, kmalloc_node,	kfree,		0, 1, 1);
+DEFINE_TEST_ALLOC(test, kzalloc,	kfree,		0, 1, 0);
+DEFINE_TEST_ALLOC(test, kzalloc_node,	kfree,		0, 1, 1);
+DEFINE_TEST_ALLOC(test, vmalloc,	vfree,		0, 0, 0);
+DEFINE_TEST_ALLOC(test, vmalloc_node,	vfree,		0, 0, 1);
+DEFINE_TEST_ALLOC(test, vzalloc,	vfree,		0, 0, 0);
+DEFINE_TEST_ALLOC(test, vzalloc_node,	vfree,		0, 0, 1);
+DEFINE_TEST_ALLOC(test, kvmalloc,	kvfree,		0, 1, 0);
+DEFINE_TEST_ALLOC(test, kvmalloc_node,	kvfree,		0, 1, 1);
+DEFINE_TEST_ALLOC(test, kvzalloc,	kvfree,		0, 1, 0);
+DEFINE_TEST_ALLOC(test, kvzalloc_node,	kvfree,		0, 1, 1);
+DEFINE_TEST_ALLOC(test, devm_kmalloc,	devm_kfree,	1, 1, 0);
+DEFINE_TEST_ALLOC(test, devm_kzalloc,	devm_kfree,	1, 1, 0);
+
+static void overflow_allocation_test(struct kunit *test)
+{
+	const char device_name[] = "overflow-test";
+	struct device *dev;
+
+	/* Create dummy device for devm_kmalloc()-family tests. */
+	dev = root_device_register(device_name);
+	if (IS_ERR(dev))
+		kunit_warn(test, "Cannot register test device\n");
+
+	test_kmalloc(test, NULL);
+	test_kmalloc_node(test, NULL);
+	test_kzalloc(test, NULL);
+	test_kzalloc_node(test, NULL);
+	test_kvmalloc(test, NULL);
+	test_kvmalloc_node(test, NULL);
+	test_kvzalloc(test, NULL);
+	test_kvzalloc_node(test, NULL);
+	test_vmalloc(test, NULL);
+	test_vmalloc_node(test, NULL);
+	test_vzalloc(test, NULL);
+	test_vzalloc_node(test, NULL);
+	test_devm_kmalloc(test, dev);
+	test_devm_kzalloc(test, dev);
+
+	device_unregister(dev);
+}
+
+static struct kunit_case overflow_test_cases[] = {
+	KUNIT_CASE(overflow_calculation_test),
+	KUNIT_CASE(overflow_shift_test),
+	KUNIT_CASE(overflow_allocation_test),
+	{}
+};
+
+static struct kunit_suite overflow_test_suite = {
+	.name = "overflow",
+	.test_cases = overflow_test_cases,
+};
+
+kunit_test_suites(&overflow_test_suite);
+
+MODULE_LICENSE("GPL v2");
-- 
2.26.2