[PATCH v2 2/6] lib/math: Add int_log test suite

Kees Cook
2025-02-11T00:31:36Z

From: Bruno Sobreira França <brunofrancadevsec@gmail.com>

This commit introduces KUnit tests for the intlog2 and intlog10
functions, which compute logarithms in base 2 and base 10, respectively.
The tests cover a range of inputs to ensure the correctness of these
functions across common and edge cases.

Signed-off-by: Bruno Sobreira França <brunofrancadevsec@gmail.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Link: https://lore.kernel.org/r/20241202075545.3648096-3-davidgow@google.com
Signed-off-by: Kees Cook <kees@kernel.org>
---
lib/Kconfig.debug | 11 +++++
lib/math/tests/Makefile | 1 +
lib/math/tests/int_log_kunit.c | 74 ++++++++++++++++++++++++++++++++++
3 files changed, 86 insertions(+)
create mode 100644 lib/math/tests/int_log_kunit.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index b18dbfc53ca4..f30929ed1a84 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -3197,6 +3197,17 @@ config INT_SQRT_KUNIT_TEST

If unsure, say N

+config INT_LOG_KUNIT_TEST
+ tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ This option enables the KUnit test suite for the int_log library, which
+ provides two functions to compute the integer logarithm in base 2 and
+ base 10, called respectively as intlog2 and intlog10.
+
+ If unsure, say N
+
endif # RUNTIME_TESTING_MENU

config ARCH_USE_MEMTEST
diff --git a/lib/math/tests/Makefile b/lib/math/tests/Makefile
index 66b10a7f5a84..f139b73c65cb 100644
--- a/lib/math/tests/Makefile
+++ b/lib/math/tests/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only

obj-$(CONFIG_INT_POW_KUNIT_TEST) += int_pow_kunit.o
+obj-$(CONFIG_INT_LOG_KUNIT_TEST) += int_log_kunit.o
obj-$(CONFIG_RATIONAL_KUNIT_TEST) += rational_kunit.o
obj-$(CONFIG_INT_SQRT_KUNIT_TEST) += int_sqrt_kunit.o
diff --git a/lib/math/tests/int_log_kunit.c b/lib/math/tests/int_log_kunit.c
new file mode 100644
index 000000000000..14e854146cb4
--- /dev/null
+++ b/lib/math/tests/int_log_kunit.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <kunit/test.h>
+#include <linux/int_log.h>
+
+struct test_case_params {
+ u32 value;
+ unsigned int expected_result;
+ const char *name;
+};
+
+
+/* The expected result takes into account the log error */
+static const struct test_case_params intlog2_params[] = {
+ {0, 0, "Log base 2 of 0"},
+ {1, 0, "Log base 2 of 1"},
+ {2, 16777216, "Log base 2 of 2"},
+ {3, 26591232, "Log base 2 of 3"},
+ {4, 33554432, "Log base 2 of 4"},
+ {8, 50331648, "Log base 2 of 8"},
+ {16, 67108864, "Log base 2 of 16"},
+ {32, 83886080, "Log base 2 of 32"},
+ {U32_MAX, 536870911, "Log base 2 of MAX"},
+};
+
+static const struct test_case_params intlog10_params[] = {
+ {0, 0, "Log base 10 of 0"},
+ {1, 0, "Log base 10 of 1"},
+ {6, 13055203, "Log base 10 of 6"},
+ {10, 16777225, "Log base 10 of 10"},
+ {100, 33554450, "Log base 10 of 100"},
+ {1000, 50331675, "Log base 10 of 1000"},
+ {10000, 67108862, "Log base 10 of 10000"},
+ {U32_MAX, 161614247, "Log base 10 of MAX"}
+};
+
+static void get_desc(const struct test_case_params *tc, char *desc)
+{
+ strscpy(desc, tc->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+
+KUNIT_ARRAY_PARAM(intlog2, intlog2_params, get_desc);
+
+static void intlog2_test(struct kunit *test)
+{
+ const struct test_case_params *tc = (const struct test_case_params *)test->param_value;
+
+ KUNIT_EXPECT_EQ(test, tc->expected_result, intlog2(tc->value));
+}
+
+KUNIT_ARRAY_PARAM(intlog10, intlog10_params, get_desc);
+
+static void intlog10_test(struct kunit *test)
+{
+ const struct test_case_params *tc = (const struct test_case_params *)test->param_value;
+
+ KUNIT_EXPECT_EQ(test, tc->expected_result, intlog10(tc->value));
+}
+
+static struct kunit_case math_int_log_test_cases[] = {
+ KUNIT_CASE_PARAM(intlog2_test, intlog2_gen_params),
+ KUNIT_CASE_PARAM(intlog10_test, intlog10_gen_params),
+ {}
+};
+
+static struct kunit_suite int_log_test_suite = {
+ .name = "math-int_log",
+ .test_cases = math_int_log_test_cases,
+};
+
+kunit_test_suites(&int_log_test_suite);
+
+MODULE_DESCRIPTION("math.int_log KUnit test suite");
+MODULE_LICENSE("GPL");
--
2.34.1