Re: [PATCH v4 3/3] bitfield: add tests

From: Andy Shevchenko
Date: Mon Jun 18 2018 - 16:44:53 EST

On Mon, Jun 18, 2018 at 11:37 PM, Johannes Berg
<johannes@xxxxxxxxxxxxxxxx> wrote:
> Add tests for the bitfield helpers. The constant ones will all
> be folded to nothing by the compiler (if everything is correct
> in the header file), and the variable ones do some tests against
> open-coding the necessary shifts.
>
> A few test cases that should fail/warn compilation are provided
> under ifdef.

Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

Though license mismatch. Either GPL-2.0+ for SPDX, or "GPL v2" for _LICENSE().

>
> Suggested-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> ---
> lib/Kconfig.debug | 7 +++
> lib/Makefile | 1 +
> lib/test_bitfield.c | 168 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 176 insertions(+)
> create mode 100644 lib/test_bitfield.c
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index eb885942eb0f..b0870377b4d1 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1799,6 +1799,13 @@ config TEST_BITMAP
>
> If unsure, say N.
>
> +config TEST_BITFIELD
> + tristate "Test bitfield functions at runtime"
> + help
> + Enable this option to test the bitfield functions at boot.
> +
> + If unsure, say N.
> +
> config TEST_UUID
> tristate "Test functions located in the uuid module at runtime"
>
> diff --git a/lib/Makefile b/lib/Makefile
> index 84c6dcb31fbb..02ab4c1a64d1 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -68,6 +68,7 @@ obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
> obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
> obj-$(CONFIG_TEST_PRINTF) += test_printf.o
> obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
> +obj-$(CONFIG_TEST_BITFIELD) += test_bitfield.o
> obj-$(CONFIG_TEST_UUID) += test_uuid.o
> obj-$(CONFIG_TEST_PARMAN) += test_parman.o
> obj-$(CONFIG_TEST_KMOD) += test_kmod.o
> diff --git a/lib/test_bitfield.c b/lib/test_bitfield.c
> new file mode 100644
> index 000000000000..c9bf2d542244
> --- /dev/null
> +++ b/lib/test_bitfield.c
> @@ -0,0 +1,168 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Test cases for bitfield helpers.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/bitfield.h>
> +
> +#define CHECK_ENC_GET_U(tp, v, field, res) do { \
> + { \
> + u##tp _res; \
> + \
> + _res = u##tp##_encode_bits(v, field); \
> + if (_res != res) { \
> + pr_warn("u" #tp "_encode_bits(" #v ", " #field ") is 0x%llx != " #res "\n",\
> + (u64)_res); \
> + return -EINVAL; \
> + } \
> + if (u##tp##_get_bits(_res, field) != v) \
> + return -EINVAL; \
> + } \
> + } while (0)
> +
> +#define CHECK_ENC_GET_LE(tp, v, field, res) do { \
> + { \
> + __le##tp _res; \
> + \
> + _res = le##tp##_encode_bits(v, field); \
> + if (_res != cpu_to_le##tp(res)) { \
> + pr_warn("le" #tp "_encode_bits(" #v ", " #field ") is 0x%llx != 0x%llx\n",\
> + (u64)le##tp##_to_cpu(_res), \
> + (u64)(res)); \
> + return -EINVAL; \
> + } \
> + if (le##tp##_get_bits(_res, field) != v) \
> + return -EINVAL; \
> + } \
> + } while (0)
> +
> +#define CHECK_ENC_GET_BE(tp, v, field, res) do { \
> + { \
> + __be##tp _res; \
> + \
> + _res = be##tp##_encode_bits(v, field); \
> + if (_res != cpu_to_be##tp(res)) { \
> + pr_warn("be" #tp "_encode_bits(" #v ", " #field ") is 0x%llx != 0x%llx\n",\
> + (u64)be##tp##_to_cpu(_res), \
> + (u64)(res)); \
> + return -EINVAL; \
> + } \
> + if (be##tp##_get_bits(_res, field) != v) \
> + return -EINVAL; \
> + } \
> + } while (0)
> +
> +#define CHECK_ENC_GET(tp, v, field, res) do { \
> + CHECK_ENC_GET_U(tp, v, field, res); \
> + CHECK_ENC_GET_LE(tp, v, field, res); \
> + CHECK_ENC_GET_BE(tp, v, field, res); \
> + } while (0)
> +
> +static int test_constants(void)
> +{
> + /*
> + * NOTE
> + * This whole function compiles (or at least should, if everything
> + * is going according to plan) to nothing after optimisation.
> + */
> +
> + CHECK_ENC_GET(16, 1, 0x000f, 0x0001);
> + CHECK_ENC_GET(16, 3, 0x00f0, 0x0030);
> + CHECK_ENC_GET(16, 5, 0x0f00, 0x0500);
> + CHECK_ENC_GET(16, 7, 0xf000, 0x7000);
> + CHECK_ENC_GET(16, 14, 0x000f, 0x000e);
> + CHECK_ENC_GET(16, 15, 0x00f0, 0x00f0);
> +
> + CHECK_ENC_GET_U(8, 1, 0x0f, 0x01);
> + CHECK_ENC_GET_U(8, 3, 0xf0, 0x30);
> + CHECK_ENC_GET_U(8, 14, 0x0f, 0x0e);
> + CHECK_ENC_GET_U(8, 15, 0xf0, 0xf0);
> +
> + CHECK_ENC_GET(32, 1, 0x00000f00, 0x00000100);
> + CHECK_ENC_GET(32, 3, 0x0000f000, 0x00003000);
> + CHECK_ENC_GET(32, 5, 0x000f0000, 0x00050000);
> + CHECK_ENC_GET(32, 7, 0x00f00000, 0x00700000);
> + CHECK_ENC_GET(32, 14, 0x0f000000, 0x0e000000);
> + CHECK_ENC_GET(32, 15, 0xf0000000, 0xf0000000);
> +
> + CHECK_ENC_GET(64, 1, 0x00000f0000000000ull, 0x0000010000000000ull);
> + CHECK_ENC_GET(64, 3, 0x0000f00000000000ull, 0x0000300000000000ull);
> + CHECK_ENC_GET(64, 5, 0x000f000000000000ull, 0x0005000000000000ull);
> + CHECK_ENC_GET(64, 7, 0x00f0000000000000ull, 0x0070000000000000ull);
> + CHECK_ENC_GET(64, 14, 0x0f00000000000000ull, 0x0e00000000000000ull);
> + CHECK_ENC_GET(64, 15, 0xf000000000000000ull, 0xf000000000000000ull);
> +
> + return 0;
> +}
> +
> +#define CHECK(tp, mask) do { \
> + u64 v; \
> + \
> + for (v = 0; v < 1 << hweight32(mask); v++) \
> + if (tp##_encode_bits(v, mask) != v << __ffs64(mask)) \
> + return -EINVAL; \
> + } while (0)
> +
> +static int test_variables(void)
> +{
> + CHECK(u8, 0x0f);
> + CHECK(u8, 0xf0);
> + CHECK(u8, 0x38);
> +
> + CHECK(u16, 0x0038);
> + CHECK(u16, 0x0380);
> + CHECK(u16, 0x3800);
> + CHECK(u16, 0x8000);
> +
> + CHECK(u32, 0x80000000);
> + CHECK(u32, 0x7f000000);
> + CHECK(u32, 0x07e00000);
> + CHECK(u32, 0x00018000);
> +
> + CHECK(u64, 0x8000000000000000ull);
> + CHECK(u64, 0x7f00000000000000ull);
> + CHECK(u64, 0x0001800000000000ull);
> + CHECK(u64, 0x0000000080000000ull);
> + CHECK(u64, 0x000000007f000000ull);
> + CHECK(u64, 0x0000000018000000ull);
> + CHECK(u64, 0x0000001f8000000ull);
> +
> + return 0;
> +}
> +
> +static int __init test_bitfields(void)
> +{
> + int ret = test_constants();
> +
> + if (ret) {
> + pr_warn("constant tests failed!\n");
> + return ret;
> + }
> +
> + ret = test_variables();
> + if (ret) {
> + pr_warn("variable tests failed!\n");
> + return ret;
> + }
> +
> +#ifdef TEST_BITFIELD_COMPILE
> + /* these should fail compilation */
> + CHECK_ENC_GET(16, 16, 0x0f00, 0x1000);
> + u32_encode_bits(7, 0x06000000);
> +
> + /* this should at least give a warning */
> + u16_encode_bits(0, 0x60000);
> +#endif
> +
> + pr_info("tests passed\n");
> +
> + return 0;
> +}
> +module_init(test_bitfields)
> +
> +MODULE_AUTHOR("Johannes Berg <johannes@xxxxxxxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> --
> 2.14.4
>



--
With Best Regards,
Andy Shevchenko