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Date:   Mon, 10 Oct 2022 17:40:30 +0300
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Subject: Re: [PATCH] overflow: Refactor test skips for Clang-specific issues
Content-Language: en-US
To:     Kees Cook <keescook@chromium.org>,
        Nick Desaulniers <ndesaulniers@google.com>
CC:     Nathan Chancellor <nathan@kernel.org>, Tom Rix <trix@redhat.com>,
        "Daniel Latypov" <dlatypov@google.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        <llvm@lists.linux.dev>, Vitor Massaru Iha <vitor@massaru.org>,
        kernel test robot <lkp@intel.com>,
        <linux-kernel@vger.kernel.org>, <linux-hardening@vger.kernel.org>
References: <20221006230017.1833458-1-keescook@chromium.org>
From:   Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
In-Reply-To: <20221006230017.1833458-1-keescook@chromium.org>
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Thanks for updating it.
Looks good to me.

Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>

On 10/7/22 2:00 AM, Kees Cook wrote:
> Convert test exclusion into test skipping. This brings the logic for
> why a test is being skipped into the test itself, instead of having to
> spread ifdefs around the code. This will make cleanup easier as minimum
> tests get raised. Drop __maybe_unused so missed tests will be noticed
> again and clean up whitespace.
> 
> For example, clang-11 on i386:
> 
> [15:52:32] ================== overflow (18 subtests) ==================
> [15:52:32] [PASSED] u8_u8__u8_overflow_test
> [15:52:32] [PASSED] s8_s8__s8_overflow_test
> [15:52:32] [PASSED] u16_u16__u16_overflow_test
> [15:52:32] [PASSED] s16_s16__s16_overflow_test
> [15:52:32] [PASSED] u32_u32__u32_overflow_test
> [15:52:32] [PASSED] s32_s32__s32_overflow_test
> [15:52:32] [SKIPPED] u64_u64__u64_overflow_test
> [15:52:32] [SKIPPED] s64_s64__s64_overflow_test
> [15:52:32] [SKIPPED] u32_u32__int_overflow_test
> [15:52:32] [PASSED] u32_u32__u8_overflow_test
> [15:52:32] [PASSED] u8_u8__int_overflow_test
> [15:52:32] [PASSED] int_int__u8_overflow_test
> [15:52:32] [PASSED] shift_sane_test
> [15:52:32] [PASSED] shift_overflow_test
> [15:52:32] [PASSED] shift_truncate_test
> [15:52:32] [PASSED] shift_nonsense_test
> [15:52:32] [PASSED] overflow_allocation_test
> [15:52:32] [PASSED] overflow_size_helpers_test
> [15:52:32] ==================== [PASSED] overflow =====================
> [15:52:32] ============================================================
> [15:52:32] Testing complete. Ran 18 tests: passed: 15, skipped: 3
> 
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Tom Rix <trix@redhat.com>
> Cc: Daniel Latypov <dlatypov@google.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: llvm@lists.linux.dev
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>   lib/overflow_kunit.c | 52 +++++++++++++++++++++++++++++---------------
>   1 file changed, 35 insertions(+), 17 deletions(-)
> 
> diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c
> index 2914c9d36b0f..3062b33e4bb1 100644
> --- a/lib/overflow_kunit.c
> +++ b/lib/overflow_kunit.c
> @@ -16,6 +16,34 @@
>   #include <linux/types.h>
>   #include <linux/vmalloc.h>
>   
> +#define SKIP(cond, reason)		do {			\
> +	if (cond) {						\
> +		kunit_skip(test, reason);			\
> +		return;						\
> +	}							\
> +} while (0)
> +
> +/*
> + * Clang 11 and earlier generate unwanted libcalls for signed output
> + * on unsigned input.
> + */
> +#if defined(CONFIG_CC_IS_CLANG) && __clang_major__ <= 11
> +# define SKIP_SIGN_MISMATCH(t)	SKIP(t, "Clang 11 unwanted libcalls")
> +#else
> +# define SKIP_SIGN_MISMATCH(t)	do { } while (0)
> +#endif
> +
> +/*
> + * Clang 13 and earlier generate unwanted libcalls for 64-bit tests on
> + * 32-bit hosts.
> + */
> +#if defined(CONFIG_CC_IS_CLANG) && __clang_major__ <= 13 &&	\
> +    BITS_PER_LONG != 64
> +# define SKIP_64_ON_32(t)	SKIP(t, "Clang 13 unwanted libcalls")
> +#else
> +# define SKIP_64_ON_32(t)	do { } while (0)
> +#endif
> +
>   #define DEFINE_TEST_ARRAY_TYPED(t1, t2, t)			\
>   	static const struct test_ ## t1 ## _ ## t2 ## __ ## t {	\
>   		t1 a;						\
> @@ -94,7 +122,6 @@ DEFINE_TEST_ARRAY(u32) = {
>   	{-4U, 5U, 1U, -9U, -20U, true, false, true},
>   };
>   
> -#if BITS_PER_LONG == 64
>   DEFINE_TEST_ARRAY(u64) = {
>   	{0, 0, 0, 0, 0, false, false, false},
>   	{1, 1, 2, 0, 1, false, false, false},
> @@ -118,7 +145,6 @@ DEFINE_TEST_ARRAY(u64) = {
>   	 false, true, false},
>   	{-15ULL, 10ULL, -5ULL, -25ULL, -150ULL, false, false, true},
>   };
> -#endif
>   
>   DEFINE_TEST_ARRAY(s8) = {
>   	{0, 0, 0, 0, 0, false, false, false},
> @@ -194,7 +220,6 @@ DEFINE_TEST_ARRAY(s32) = {
>   	{S32_MAX, S32_MAX, -2, 0, 1, true, false, true},
>   };
>   
> -#if BITS_PER_LONG == 64
>   DEFINE_TEST_ARRAY(s64) = {
>   	{0, 0, 0, 0, 0, false, false, false},
>   
> @@ -223,7 +248,6 @@ DEFINE_TEST_ARRAY(s64) = {
>   	{-128, -1, -129, -127, 128, false, false, false},
>   	{0, -S64_MAX, -S64_MAX, S64_MAX, 0, false, false, false},
>   };
> -#endif
>   
>   #define check_one_op(t, fmt, op, sym, a, b, r, of) do {			\
>   	int _a_orig = a, _a_bump = a + 1;				\
> @@ -246,7 +270,7 @@ DEFINE_TEST_ARRAY(s64) = {
>   
>   #define DEFINE_TEST_FUNC_TYPED(n, t, fmt)				\
>   static void do_test_ ## n(struct kunit *test, const struct test_ ## n *p) \
> -{							   		\
> +{									\
>   	check_one_op(t, fmt, add, "+", p->a, p->b, p->sum, p->s_of);	\
>   	check_one_op(t, fmt, add, "+", p->b, p->a, p->sum, p->s_of);	\
>   	check_one_op(t, fmt, sub, "-", p->a, p->b, p->diff, p->d_of);	\
> @@ -254,10 +278,15 @@ static void do_test_ ## n(struct kunit *test, const struct test_ ## n *p) \
>   	check_one_op(t, fmt, mul, "*", p->b, p->a, p->prod, p->p_of);	\
>   }									\
>   									\
> -__maybe_unused								\
>   static void n ## _overflow_test(struct kunit *test) {			\
>   	unsigned i;							\
>   									\
> +	SKIP_64_ON_32(__same_type(t, u64));				\
> +	SKIP_64_ON_32(__same_type(t, s64));				\
> +	SKIP_SIGN_MISMATCH(__same_type(n ## _tests[0].a, u32) &&	\
> +			   __same_type(n ## _tests[0].b, u32) &&	\
> +			   __same_type(n ## _tests[0].sum, int));	\
> +									\
>   	for (i = 0; i < ARRAY_SIZE(n ## _tests); ++i)			\
>   		do_test_ ## n(test, &n ## _tests[i]);			\
>   	kunit_info(test, "%zu %s arithmetic tests finished\n",		\
> @@ -273,10 +302,8 @@ DEFINE_TEST_FUNC(u16, "%d");
>   DEFINE_TEST_FUNC(s16, "%d");
>   DEFINE_TEST_FUNC(u32, "%u");
>   DEFINE_TEST_FUNC(s32, "%d");
> -#if BITS_PER_LONG == 64
>   DEFINE_TEST_FUNC(u64, "%llu");
>   DEFINE_TEST_FUNC(s64, "%lld");
> -#endif
>   
>   DEFINE_TEST_ARRAY_TYPED(u32, u32, u8) = {
>   	{0, 0, 0, 0, 0, false, false, false},
> @@ -716,18 +743,9 @@ static struct kunit_case overflow_test_cases[] = {
>   	KUNIT_CASE(s16_s16__s16_overflow_test),
>   	KUNIT_CASE(u32_u32__u32_overflow_test),
>   	KUNIT_CASE(s32_s32__s32_overflow_test),
> -/* Clang 13 and earlier generate unwanted libcalls on 32-bit. */
> -#if BITS_PER_LONG == 64
>   	KUNIT_CASE(u64_u64__u64_overflow_test),
>   	KUNIT_CASE(s64_s64__s64_overflow_test),
> -#endif
> -/*
> - * Clang 11 and earlier generate unwanted libcalls for signed output, unsigned
> - * input.
> - */
> -#if !(defined(CONFIG_CC_IS_CLANG) && __clang_major__ <= 11)
>   	KUNIT_CASE(u32_u32__int_overflow_test),
> -#endif
>   	KUNIT_CASE(u32_u32__u8_overflow_test),
>   	KUNIT_CASE(u8_u8__int_overflow_test),
>   	KUNIT_CASE(int_int__u8_overflow_test),