From: Yury Norov <ynorov@nvidia.com>
To: david.laight.linux@gmail.com
Cc: Nathan Chancellor <nathan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Yury Norov <yury.norov@gmail.com>,
Lucas De Marchi <lucas.demarchi@intel.com>,
Jani Nikula <jani.nikula@intel.com>,
Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH next 13/14] test_bits: Change all the tests to be compile-time tests
Date: Sat, 7 Feb 2026 23:37:49 -0500 [thread overview]
Message-ID: <aYgTHfhxDws-D6yl@yury> (raw)
In-Reply-To: <20260121145731.3623-14-david.laight.linux@gmail.com>
On Wed, Jan 21, 2026 at 02:57:30PM +0000, david.laight.linux@gmail.com wrote:
> From: David Laight <david.laight.linux@gmail.com>
>
> Since all the GENMASK() values are compile-time constants they can
> be tested with BUILD_BUG_ON() rather than KUNIT_EXPECT_EQ().
>
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
I thought, KUNIT invented this EXPECT_EQ macro for a nice printing
and some accounting. If you want to make sure that __GENMASK() is a
compile-time expression, it's OK. But I'd rather keep the existing
KUNIT_EXPECT_EQ() and add
BUILD_BUG_ON(!__builtin_constant_p(GENMASK()))
next to that. This is actually how test_bitmap_const_eval() works.
Thanks,
Yury
> ---
> lib/tests/test_bits.c | 90 +++++++++++++++++++++----------------------
> 1 file changed, 45 insertions(+), 45 deletions(-)
>
> diff --git a/lib/tests/test_bits.c b/lib/tests/test_bits.c
> index 36eb4661e78b..4d3a895f490c 100644
> --- a/lib/tests/test_bits.c
> +++ b/lib/tests/test_bits.c
> @@ -32,30 +32,30 @@ static_assert(assert_type(u64, GENMASK_U64(63, 0)) == U64_MAX);
>
> static void __genmask_test(struct kunit *test)
> {
> - KUNIT_EXPECT_EQ(test, 1ul, __GENMASK(0, 0));
> - KUNIT_EXPECT_EQ(test, 3ul, __GENMASK(1, 0));
> - KUNIT_EXPECT_EQ(test, 6ul, __GENMASK(2, 1));
> - KUNIT_EXPECT_EQ(test, 0xFFFFFFFFul, __GENMASK(31, 0));
> + BUILD_BUG_ON(__GENMASK(0, 0) != 1ul);
> + BUILD_BUG_ON(__GENMASK(1, 0) != 3ul);
> + BUILD_BUG_ON(__GENMASK(2, 1) != 6ul);
> + BUILD_BUG_ON(__GENMASK(31, 0) != 0xFFFFFFFFul);
> }
>
> static void __genmask_ull_test(struct kunit *test)
> {
> - KUNIT_EXPECT_EQ(test, 1ull, __GENMASK_ULL(0, 0));
> - KUNIT_EXPECT_EQ(test, 3ull, __GENMASK_ULL(1, 0));
> - KUNIT_EXPECT_EQ(test, 0x000000ffffe00000ull, __GENMASK_ULL(39, 21));
> - KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, __GENMASK_ULL(63, 0));
> + BUILD_BUG_ON(__GENMASK_ULL(0, 0) != 1ull);
> + BUILD_BUG_ON(__GENMASK_ULL(1, 0) != 3ull);
> + BUILD_BUG_ON(__GENMASK_ULL(39, 21) != 0x000000ffffe00000ull);
> + BUILD_BUG_ON(__GENMASK_ULL(63, 0) != 0xffffffffffffffffull);
> }
>
> static void genmask_test(struct kunit *test)
> {
> - KUNIT_EXPECT_EQ(test, 1ul, GENMASK(0, 0));
> - KUNIT_EXPECT_EQ(test, 3ul, GENMASK(1, 0));
> - KUNIT_EXPECT_EQ(test, 6ul, GENMASK(2, 1));
> - KUNIT_EXPECT_EQ(test, 0xFFFFFFFFul, GENMASK(31, 0));
> + BUILD_BUG_ON(GENMASK(0, 0) != 1ul);
> + BUILD_BUG_ON(GENMASK(1, 0) != 3ul);
> + BUILD_BUG_ON(GENMASK(2, 1) != 6ul);
> + BUILD_BUG_ON(GENMASK(31, 0) != 0xFFFFFFFFul);
>
> - KUNIT_EXPECT_EQ(test, 1u, GENMASK_U8(0, 0));
> - KUNIT_EXPECT_EQ(test, 3u, GENMASK_U16(1, 0));
> - KUNIT_EXPECT_EQ(test, 0x10000, GENMASK_U32(16, 16));
> + BUILD_BUG_ON(GENMASK_U8(0, 0) != 1u);
> + BUILD_BUG_ON(GENMASK_U16(1, 0) != 3u);
> + BUILD_BUG_ON(GENMASK_U32(16, 16) != 0x10000);
>
> #ifdef TEST_GENMASK_FAILURES
> /* these should fail compilation */
> @@ -75,10 +75,10 @@ static void genmask_test(struct kunit *test)
>
> static void genmask_ull_test(struct kunit *test)
> {
> - KUNIT_EXPECT_EQ(test, 1ull, GENMASK_ULL(0, 0));
> - KUNIT_EXPECT_EQ(test, 3ull, GENMASK_ULL(1, 0));
> - KUNIT_EXPECT_EQ(test, 0x000000ffffe00000ull, GENMASK_ULL(39, 21));
> - KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_ULL(63, 0));
> + BUILD_BUG_ON(GENMASK_ULL(0, 0) != 1ull);
> + BUILD_BUG_ON(GENMASK_ULL(1, 0) != 3ull);
> + BUILD_BUG_ON(GENMASK_ULL(39, 21) != 0x000000ffffe00000ull);
> + BUILD_BUG_ON(GENMASK_ULL(63, 0) != 0xffffffffffffffffull);
>
> #ifdef TEST_GENMASK_FAILURES
> /* these should fail compilation */
> @@ -92,23 +92,23 @@ static void genmask_u128_test(struct kunit *test)
> {
> #ifdef CONFIG_ARCH_SUPPORTS_INT128
> /* Below 64 bit masks */
> - KUNIT_EXPECT_EQ(test, 0x0000000000000001ull, GENMASK_U128(0, 0));
> - KUNIT_EXPECT_EQ(test, 0x0000000000000003ull, GENMASK_U128(1, 0));
> - KUNIT_EXPECT_EQ(test, 0x0000000000000006ull, GENMASK_U128(2, 1));
> - KUNIT_EXPECT_EQ(test, 0x00000000ffffffffull, GENMASK_U128(31, 0));
> - KUNIT_EXPECT_EQ(test, 0x000000ffffe00000ull, GENMASK_U128(39, 21));
> - KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_U128(63, 0));
> + BUILD_BUG_ON(GENMASK_U128(0, 0) != 0x0000000000000001ull);
> + BUILD_BUG_ON(GENMASK_U128(1, 0) != 0x0000000000000003ull);
> + BUILD_BUG_ON(GENMASK_U128(2, 1) != 0x0000000000000006ull);
> + BUILD_BUG_ON(GENMASK_U128(31, 0) != 0x00000000ffffffffull);
> + BUILD_BUG_ON(GENMASK_U128(39, 21) != 0x000000ffffe00000ull);
> + BUILD_BUG_ON(GENMASK_U128(63, 0) != 0xffffffffffffffffull);
>
> /* Above 64 bit masks - only 64 bit portion can be validated once */
> - KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_U128(64, 0) >> 1);
> - KUNIT_EXPECT_EQ(test, 0x00000000ffffffffull, GENMASK_U128(81, 50) >> 50);
> - KUNIT_EXPECT_EQ(test, 0x0000000000ffffffull, GENMASK_U128(87, 64) >> 64);
> - KUNIT_EXPECT_EQ(test, 0x0000000000ff0000ull, GENMASK_U128(87, 80) >> 64);
> -
> - KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, GENMASK_U128(127, 0) >> 64);
> - KUNIT_EXPECT_EQ(test, 0xffffffffffffffffull, (u64)GENMASK_U128(127, 0));
> - KUNIT_EXPECT_EQ(test, 0x0000000000000003ull, GENMASK_U128(127, 126) >> 126);
> - KUNIT_EXPECT_EQ(test, 0x0000000000000001ull, GENMASK_U128(127, 127) >> 127);
> + BUILD_BUG_ON(GENMASK_U128(64, 0) >> 1 != 0xffffffffffffffffull);
> + BUILD_BUG_ON(GENMASK_U128(81, 50) >> 50 != 0x00000000ffffffffull);
> + BUILD_BUG_ON(GENMASK_U128(87, 64) >> 64 != 0x0000000000ffffffull);
> + BUILD_BUG_ON(GENMASK_U128(87, 80) >> 64 != 0x0000000000ff0000ull);
> +
> + BUILD_BUG_ON(GENMASK_U128(127, 0) >> 64 != 0xffffffffffffffffull);
> + BUILD_BUG_ON((u64)GENMASK_U128(127, 0) != 0xffffffffffffffffull);
> + BUILD_BUG_ON(GENMASK_U128(127, 126) >> 126 != 0x0000000000000003ull);
> + BUILD_BUG_ON(GENMASK_U128(127, 127) >> 127 != 0x0000000000000001ull);
> #ifdef TEST_GENMASK_FAILURES
> /* these should fail compilation */
> GENMASK_U128(0, 1);
> @@ -129,21 +129,21 @@ static void genmask_input_check_test(struct kunit *test)
> OPTIMIZER_HIDE_VAR(w);
>
> /* Unknown input */
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, 0, 32));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, x, 32));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(x, y, 32));
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(x, 0, 32) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(0, x, 32) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(x, y, 32) != 0);
>
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, 0, 32));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(0, z, 32));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(z, w, 32));
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(z, 0, 32) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(0, z, 32) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(z, w, 32) != 0);
>
> /* Valid input */
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(1, 1, 32));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(39, 21, 64));
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(1, 1, 32) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(39, 21, 64) != 0);
>
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(100, 80, 128));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(110, 65, 128));
> - KUNIT_EXPECT_EQ(test, 0, GENMASK_INPUT_CHECK(127, 0, 128));
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(100, 80, 128) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(110, 65, 128) != 0);
> + BUILD_BUG_ON(GENMASK_INPUT_CHECK(127, 0, 128) != 0);
> }
>
>
> --
> 2.39.5
next prev parent reply other threads:[~2026-02-08 4:39 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-21 14:57 [PATCH next 00/14] bits: De-bloat expansion of GENMASK() david.laight.linux
2026-01-21 14:57 ` [PATCH next 01/14] overflow: Reduce expansion of __type_max() david.laight.linux
2026-01-21 20:59 ` Kees Cook
2026-02-02 16:45 ` Yury Norov
2026-01-21 14:57 ` [PATCH next 02/14] kbuild: Add W=c for additional compile time checks david.laight.linux
2026-02-02 18:33 ` Yury Norov
2026-02-02 20:07 ` David Laight
2026-02-03 4:47 ` Nathan Chancellor
2026-02-03 11:14 ` David Laight
2026-02-03 19:41 ` Yury Norov
2026-01-21 14:57 ` [PATCH next 03/14] media: videobuf2-core: Use static_assert() for sanity check david.laight.linux
2026-01-21 14:57 ` [PATCH next 04/14] media: atomisp: " david.laight.linux
2026-01-21 14:57 ` [PATCH next 05/14] ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD david.laight.linux
2026-01-23 15:44 ` Simon Horman
2026-01-21 14:57 ` [PATCH next 06/14] asm-generic: include linux/bits.h not vdso/bits.h david.laight.linux
2026-01-21 14:57 ` [PATCH next 07/14] x86/tlb: " david.laight.linux
2026-01-21 14:57 ` [PATCH next 08/14] bits: simplify GENMASK_TYPE() david.laight.linux
2026-02-08 2:36 ` Yury Norov
2026-02-09 9:42 ` David Laight
2026-01-21 14:57 ` [PATCH next 09/14] bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values david.laight.linux
2026-01-21 14:57 ` [PATCH next 10/14] bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx() david.laight.linux
2026-02-08 3:31 ` Yury Norov
2026-02-08 11:42 ` David Laight
2026-02-08 21:20 ` Yury Norov
2026-02-08 22:27 ` David Laight
2026-01-21 14:57 ` [PATCH next 11/14] bit: Strengthen compile-time tests in GENMASK() and BIT() david.laight.linux
2026-01-21 18:43 ` Vincent Mailhol
2026-01-21 19:14 ` David Laight
2026-01-22 1:11 ` kernel test robot
2026-01-22 10:25 ` David Laight
2026-01-22 20:10 ` David Laight
2026-01-22 4:41 ` kernel test robot
2026-01-22 10:33 ` David Laight
2026-01-22 14:26 ` Andy Shevchenko
2026-01-22 14:55 ` David Laight
2026-01-23 1:25 ` Philip Li
2026-01-23 8:01 ` Vincent Mailhol
2026-01-23 8:11 ` Andy Shevchenko
2026-01-23 8:20 ` Al Viro
2026-01-23 8:24 ` Andy Shevchenko
2026-01-23 8:32 ` Vincent Mailhol
2026-01-23 8:46 ` Andy Shevchenko
2026-01-23 1:24 ` Philip Li
2026-01-21 14:57 ` [PATCH next 12/14] bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h david.laight.linux
2026-01-21 15:17 ` Thomas Weißschuh
2026-01-21 19:24 ` David Laight
2026-01-22 7:39 ` Thomas Weißschuh
2026-01-22 0:50 ` kernel test robot
2026-01-22 1:23 ` kernel test robot
2026-01-22 10:30 ` David Laight
2026-02-07 22:40 ` Thomas Gleixner
2026-02-08 4:23 ` Yury Norov
2026-01-21 14:57 ` [PATCH next 13/14] test_bits: Change all the tests to be compile-time tests david.laight.linux
2026-02-08 4:37 ` Yury Norov [this message]
2026-02-08 11:32 ` David Laight
2026-01-21 14:57 ` [PATCH next 14/14] test_bits: include some invalid input tests for GENMASK_INPUT_CHECK() david.laight.linux
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