[PATCH v5 next 9/9] lib: test_mul_u64_u64_div_u64: Test the 32bit code on 64bit

David Laight
2025-11-05T20:10:59Z

There are slight differences in the mul_u64_add_u64_div_u64() code
between 32bit and 64bit systems.

Compile and test the 32bit version on 64bit hosts for better test
coverage.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
Reviewed-by: Nicolas Pitre <npitre@baylibre.com>
---

Changes for v4:
- Fix build on non x86-64

lib/math/test_mul_u64_u64_div_u64.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)

diff --git a/lib/math/test_mul_u64_u64_div_u64.c b/lib/math/test_mul_u64_u64_div_u64.c
index d8d2c18c4614..338d014f0c73 100644
--- a/lib/math/test_mul_u64_u64_div_u64.c
+++ b/lib/math/test_mul_u64_u64_div_u64.c
@@ -74,6 +74,10 @@ done
*/

static u64 test_mul_u64_add_u64_div_u64(u64 a, u64 b, u64 c, u64 d);
+#if __LONG_WIDTH__ >= 64
+#define TEST_32BIT_DIV
+static u64 test_mul_u64_add_u64_div_u64_32bit(u64 a, u64 b, u64 c, u64 d);
+#endif

static int __init test_run(unsigned int fn_no, const char *fn_name)
{
@@ -100,6 +104,12 @@ static int __init test_run(unsigned int fn_no, const char *fn_name)
result = test_mul_u64_add_u64_div_u64(a, b, 0, d);
result_up = test_mul_u64_add_u64_div_u64(a, b, d - 1, d);
break;
+#ifdef TEST_32BIT_DIV
+ case 2:
+ result = test_mul_u64_add_u64_div_u64_32bit(a, b, 0, d);
+ result_up = test_mul_u64_add_u64_div_u64_32bit(a, b, d - 1, d);
+ break;
+#endif
}

tests += 2;
@@ -131,6 +141,10 @@ static int __init test_init(void)
return -EINVAL;
if (test_run(1, "test_mul_u64_u64_div_u64"))
return -EINVAL;
+#ifdef TEST_32BIT_DIV
+ if (test_run(2, "test_mul_u64_u64_div_u64_32bit"))
+ return -EINVAL;
+#endif
return 0;
}

@@ -153,6 +167,21 @@ static void __exit test_exit(void)

#include "div64.c"

+#ifdef TEST_32BIT_DIV
+/* Recompile the generic code for 32bit long */
+#undef test_mul_u64_add_u64_div_u64
+#define test_mul_u64_add_u64_div_u64 test_mul_u64_add_u64_div_u64_32bit
+#undef BITS_PER_ITER
+#define BITS_PER_ITER 16
+
+#define mul_u64_u64_add_u64 mul_u64_u64_add_u64_32bit
+#undef mul_u64_long_add_u64
+#undef add_u64_long
+#undef mul_add
+
+#include "div64.c"
+#endif
+
module_init(test_init);
module_exit(test_exit);

--
2.39.5