[PATCH v5 next 5/9] lib: Add tests for mul_u64_u64_div_u64_roundup()

David Laight
2025-11-05T20:10:56Z

Replicate the existing mul_u64_u64_div_u64() test cases with round up.
Update the shell script that verifies the table, remove the comment
markers so that it can be directly pasted into a shell.

Rename the divisor from 'c' to 'd' to match mul_u64_add_u64_div_u64().

It any tests fail then fail the module load with -EINVAL.

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

Changes for v3:
- Rename 'c' to 'd' to match mul_u64_add_u64_div_u64()

Changes for v4:
- Fix shell script that verifies the table

lib/math/test_mul_u64_u64_div_u64.c | 122 +++++++++++++++++-----------
1 file changed, 73 insertions(+), 49 deletions(-)

diff --git a/lib/math/test_mul_u64_u64_div_u64.c b/lib/math/test_mul_u64_u64_div_u64.c
index 58d058de4e73..4d5e4e5dac67 100644
--- a/lib/math/test_mul_u64_u64_div_u64.c
+++ b/lib/math/test_mul_u64_u64_div_u64.c
@@ -10,61 +10,73 @@
#include <linux/printk.h>
#include <linux/math64.h>

-typedef struct { u64 a; u64 b; u64 c; u64 result; } test_params;
+typedef struct { u64 a; u64 b; u64 d; u64 result; uint round_up;} test_params;

static test_params test_values[] = {
/* this contains many edge values followed by a couple random values */
-{ 0xb, 0x7, 0x3, 0x19 },
-{ 0xffff0000, 0xffff0000, 0xf, 0x1110eeef00000000 },
-{ 0xffffffff, 0xffffffff, 0x1, 0xfffffffe00000001 },
-{ 0xffffffff, 0xffffffff, 0x2, 0x7fffffff00000000 },
-{ 0x1ffffffff, 0xffffffff, 0x2, 0xfffffffe80000000 },
-{ 0x1ffffffff, 0xffffffff, 0x3, 0xaaaaaaa9aaaaaaab },
-{ 0x1ffffffff, 0x1ffffffff, 0x4, 0xffffffff00000000 },
-{ 0xffff000000000000, 0xffff000000000000, 0xffff000000000001, 0xfffeffffffffffff },
-{ 0x3333333333333333, 0x3333333333333333, 0x5555555555555555, 0x1eb851eb851eb851 },
-{ 0x7fffffffffffffff, 0x2, 0x3, 0x5555555555555554 },
-{ 0xffffffffffffffff, 0x2, 0x8000000000000000, 0x3 },
-{ 0xffffffffffffffff, 0x2, 0xc000000000000000, 0x2 },
-{ 0xffffffffffffffff, 0x4000000000000004, 0x8000000000000000, 0x8000000000000007 },
-{ 0xffffffffffffffff, 0x4000000000000001, 0x8000000000000000, 0x8000000000000001 },
-{ 0xffffffffffffffff, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000001 },
-{ 0xfffffffffffffffe, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000000 },
-{ 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffe, 0x8000000000000001 },
-{ 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffd, 0x8000000000000002 },
-{ 0x7fffffffffffffff, 0xffffffffffffffff, 0xc000000000000000, 0xaaaaaaaaaaaaaaa8 },
-{ 0xffffffffffffffff, 0x7fffffffffffffff, 0xa000000000000000, 0xccccccccccccccca },
-{ 0xffffffffffffffff, 0x7fffffffffffffff, 0x9000000000000000, 0xe38e38e38e38e38b },
-{ 0x7fffffffffffffff, 0x7fffffffffffffff, 0x5000000000000000, 0xccccccccccccccc9 },
-{ 0xffffffffffffffff, 0xfffffffffffffffe, 0xffffffffffffffff, 0xfffffffffffffffe },
-{ 0xe6102d256d7ea3ae, 0x70a77d0be4c31201, 0xd63ec35ab3220357, 0x78f8bf8cc86c6e18 },
-{ 0xf53bae05cb86c6e1, 0x3847b32d2f8d32e0, 0xcfd4f55a647f403c, 0x42687f79d8998d35 },
-{ 0x9951c5498f941092, 0x1f8c8bfdf287a251, 0xa3c8dc5f81ea3fe2, 0x1d887cb25900091f },
-{ 0x374fee9daa1bb2bb, 0x0d0bfbff7b8ae3ef, 0xc169337bd42d5179, 0x03bb2dbaffcbb961 },
-{ 0xeac0d03ac10eeaf0, 0x89be05dfa162ed9b, 0x92bb1679a41f0e4b, 0xdc5f5cc9e270d216 },
+{ 0xb, 0x7, 0x3, 0x19, 1 },
+{ 0xffff0000, 0xffff0000, 0xf, 0x1110eeef00000000, 0 },
+{ 0xffffffff, 0xffffffff, 0x1, 0xfffffffe00000001, 0 },
+{ 0xffffffff, 0xffffffff, 0x2, 0x7fffffff00000000, 1 },
+{ 0x1ffffffff, 0xffffffff, 0x2, 0xfffffffe80000000, 1 },
+{ 0x1ffffffff, 0xffffffff, 0x3, 0xaaaaaaa9aaaaaaab, 0 },
+{ 0x1ffffffff, 0x1ffffffff, 0x4, 0xffffffff00000000, 1 },
+{ 0xffff000000000000, 0xffff000000000000, 0xffff000000000001, 0xfffeffffffffffff, 1 },
+{ 0x3333333333333333, 0x3333333333333333, 0x5555555555555555, 0x1eb851eb851eb851, 1 },
+{ 0x7fffffffffffffff, 0x2, 0x3, 0x5555555555555554, 1 },
+{ 0xffffffffffffffff, 0x2, 0x8000000000000000, 0x3, 1 },
+{ 0xffffffffffffffff, 0x2, 0xc000000000000000, 0x2, 1 },
+{ 0xffffffffffffffff, 0x4000000000000004, 0x8000000000000000, 0x8000000000000007, 1 },
+{ 0xffffffffffffffff, 0x4000000000000001, 0x8000000000000000, 0x8000000000000001, 1 },
+{ 0xffffffffffffffff, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000001, 0 },
+{ 0xfffffffffffffffe, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000000, 1 },
+{ 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffe, 0x8000000000000001, 1 },
+{ 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffd, 0x8000000000000002, 1 },
+{ 0x7fffffffffffffff, 0xffffffffffffffff, 0xc000000000000000, 0xaaaaaaaaaaaaaaa8, 1 },
+{ 0xffffffffffffffff, 0x7fffffffffffffff, 0xa000000000000000, 0xccccccccccccccca, 1 },
+{ 0xffffffffffffffff, 0x7fffffffffffffff, 0x9000000000000000, 0xe38e38e38e38e38b, 1 },
+{ 0x7fffffffffffffff, 0x7fffffffffffffff, 0x5000000000000000, 0xccccccccccccccc9, 1 },
+{ 0xffffffffffffffff, 0xfffffffffffffffe, 0xffffffffffffffff, 0xfffffffffffffffe, 0 },
+{ 0xe6102d256d7ea3ae, 0x70a77d0be4c31201, 0xd63ec35ab3220357, 0x78f8bf8cc86c6e18, 1 },
+{ 0xf53bae05cb86c6e1, 0x3847b32d2f8d32e0, 0xcfd4f55a647f403c, 0x42687f79d8998d35, 1 },
+{ 0x9951c5498f941092, 0x1f8c8bfdf287a251, 0xa3c8dc5f81ea3fe2, 0x1d887cb25900091f, 1 },
+{ 0x374fee9daa1bb2bb, 0x0d0bfbff7b8ae3ef, 0xc169337bd42d5179, 0x03bb2dbaffcbb961, 1 },
+{ 0xeac0d03ac10eeaf0, 0x89be05dfa162ed9b, 0x92bb1679a41f0e4b, 0xdc5f5cc9e270d216, 1 },
};

/*
* The above table can be verified with the following shell script:
- *
- * #!/bin/sh
- * sed -ne 's/^{ \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\) },$/\1 \2 \3 \4/p' \
- * lib/math/test_mul_u64_u64_div_u64.c |
- * while read a b c r; do
- * expected=$( printf "obase=16; ibase=16; %X * %X / %X\n" $a $b $c | bc )
- * given=$( printf "%X\n" $r )
- * if [ "$expected" = "$given" ]; then
- * echo "$a * $b / $c = $r OK"
- * else
- * echo "$a * $b / $c = $r is wrong" >&2
- * echo "should be equivalent to 0x$expected" >&2
- * exit 1
- * fi
- * done
+
+#!/bin/sh
+sed -ne 's/^{ \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\) },$/\1 \2 \3 \4 \5/p' \
+ lib/math/test_mul_u64_u64_div_u64.c |
+while read a b d r e; do
+ expected=$( printf "obase=16; ibase=16; %X * %X / %X\n" $a $b $d | bc )
+ given=$( printf "%X\n" $r )
+ if [ "$expected" = "$given" ]; then
+ echo "$a * $b / $d = $r OK"
+ else
+ echo "$a * $b / $d = $r is wrong" >&2
+ echo "should be equivalent to 0x$expected" >&2
+ exit 1
+ fi
+ expected=$( printf "obase=16; ibase=16; (%X * %X + %X) / %X\n" $a $b $((d-1)) $d | bc )
+ given=$( printf "%X\n" $((r + e)) )
+ if [ "$expected" = "$given" ]; then
+ echo "$a * $b +/ $d = $(printf '%#x' $((r + e))) OK"
+ else
+ echo "$a * $b +/ $d = $(printf '%#x' $((r + e))) is wrong" >&2
+ echo "should be equivalent to 0x$expected" >&2
+ exit 1
+ fi
+done
+
*/

static int __init test_init(void)
{
+ int errors = 0;
+ int tests = 0;
int i;

pr_info("Starting mul_u64_u64_div_u64() test\n");
@@ -72,19 +84,31 @@ static int __init test_init(void)
for (i = 0; i < ARRAY_SIZE(test_values); i++) {
u64 a = test_values[i].a;
u64 b = test_values[i].b;
- u64 c = test_values[i].c;
+ u64 d = test_values[i].d;
u64 expected_result = test_values[i].result;
- u64 result = mul_u64_u64_div_u64(a, b, c);
+ u64 result = mul_u64_u64_div_u64(a, b, d);
+ u64 result_up = mul_u64_u64_div_u64_roundup(a, b, d);
+
+ tests += 2;

if (result != expected_result) {
- pr_err("ERROR: 0x%016llx * 0x%016llx / 0x%016llx\n", a, b, c);
+ pr_err("ERROR: 0x%016llx * 0x%016llx / 0x%016llx\n", a, b, d);
pr_err("ERROR: expected result: %016llx\n", expected_result);
pr_err("ERROR: obtained result: %016llx\n", result);
+ errors++;
+ }
+ expected_result += test_values[i].round_up;
+ if (result_up != expected_result) {
+ pr_err("ERROR: 0x%016llx * 0x%016llx +/ 0x%016llx\n", a, b, d);
+ pr_err("ERROR: expected result: %016llx\n", expected_result);
+ pr_err("ERROR: obtained result: %016llx\n", result_up);
+ errors++;
}
}

- pr_info("Completed mul_u64_u64_div_u64() test\n");
- return 0;
+ pr_info("Completed mul_u64_u64_div_u64() test, %d tests, %d errors\n",
+ tests, errors);
+ return errors ? -EINVAL : 0;
}

static void __exit test_exit(void)
--
2.39.5