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-rw-r--r--lib/Kconfig.debug10
-rw-r--r--lib/math/Makefile2
-rw-r--r--lib/math/test_div64.c249
3 files changed, 261 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2779c29d9981..b6e7f50d984f 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2027,6 +2027,16 @@ config TEST_SORT
If unsure, say N.
+config TEST_DIV64
+ tristate "64bit/32bit division and modulo test"
+ depends on DEBUG_KERNEL || m
+ help
+ Enable this to turn on 'do_div()' function test. This test is
+ executed only once during system boot (so affects only boot time),
+ or at module load time.
+
+ If unsure, say N.
+
config KPROBES_SANITY_TEST
bool "Kprobes sanity tests"
depends on DEBUG_KERNEL
diff --git a/lib/math/Makefile b/lib/math/Makefile
index be6909e943bd..7456edb864fc 100644
--- a/lib/math/Makefile
+++ b/lib/math/Makefile
@@ -4,3 +4,5 @@ obj-y += div64.o gcd.o lcm.o int_pow.o int_sqrt.o reciprocal_div.o
obj-$(CONFIG_CORDIC) += cordic.o
obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o
obj-$(CONFIG_RATIONAL) += rational.o
+
+obj-$(CONFIG_TEST_DIV64) += test_div64.o
diff --git a/lib/math/test_div64.c b/lib/math/test_div64.c
new file mode 100644
index 000000000000..eca8e8c6afe0
--- /dev/null
+++ b/lib/math/test_div64.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Maciej W. Rozycki
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/time64.h>
+#include <linux/types.h>
+
+#include <asm/div64.h>
+
+#define TEST_DIV64_N_ITER 1024
+
+static const u64 test_div64_dividents[] = {
+ 0x00000000ab275080,
+ 0x0000000fe73c1959,
+ 0x000000e54c0a74b1,
+ 0x00000d4398ff1ef9,
+ 0x0000a18c2ee1c097,
+ 0x00079fb80b072e4a,
+ 0x0072db27380dd689,
+ 0x0842f488162e2284,
+ 0xf66745411d8ab063,
+};
+#define SIZE_DIV64_DIVIDENTS ARRAY_SIZE(test_div64_dividents)
+
+#define TEST_DIV64_DIVISOR_0 0x00000009
+#define TEST_DIV64_DIVISOR_1 0x0000007c
+#define TEST_DIV64_DIVISOR_2 0x00000204
+#define TEST_DIV64_DIVISOR_3 0x0000cb5b
+#define TEST_DIV64_DIVISOR_4 0x00010000
+#define TEST_DIV64_DIVISOR_5 0x0008a880
+#define TEST_DIV64_DIVISOR_6 0x003fd3ae
+#define TEST_DIV64_DIVISOR_7 0x0b658fac
+#define TEST_DIV64_DIVISOR_8 0xdc08b349
+
+static const u32 test_div64_divisors[] = {
+ TEST_DIV64_DIVISOR_0,
+ TEST_DIV64_DIVISOR_1,
+ TEST_DIV64_DIVISOR_2,
+ TEST_DIV64_DIVISOR_3,
+ TEST_DIV64_DIVISOR_4,
+ TEST_DIV64_DIVISOR_5,
+ TEST_DIV64_DIVISOR_6,
+ TEST_DIV64_DIVISOR_7,
+ TEST_DIV64_DIVISOR_8,
+};
+#define SIZE_DIV64_DIVISORS ARRAY_SIZE(test_div64_divisors)
+
+static const struct {
+ u64 quotient;
+ u32 remainder;
+} test_div64_results[SIZE_DIV64_DIVISORS][SIZE_DIV64_DIVIDENTS] = {
+ {
+ { 0x0000000013045e47, 0x00000001 },
+ { 0x000000000161596c, 0x00000030 },
+ { 0x000000000054e9d4, 0x00000130 },
+ { 0x000000000000d776, 0x0000278e },
+ { 0x000000000000ab27, 0x00005080 },
+ { 0x00000000000013c4, 0x0004ce80 },
+ { 0x00000000000002ae, 0x001e143c },
+ { 0x000000000000000f, 0x0033e56c },
+ { 0x0000000000000000, 0xab275080 },
+ }, {
+ { 0x00000001c45c02d1, 0x00000000 },
+ { 0x0000000020d5213c, 0x00000049 },
+ { 0x0000000007e3d65f, 0x000001dd },
+ { 0x0000000000140531, 0x000065ee },
+ { 0x00000000000fe73c, 0x00001959 },
+ { 0x000000000001d637, 0x0004e5d9 },
+ { 0x0000000000003fc9, 0x000713bb },
+ { 0x0000000000000165, 0x029abe7d },
+ { 0x0000000000000012, 0x6e9f7e37 },
+ }, {
+ { 0x000000197a3a0cf7, 0x00000002 },
+ { 0x00000001d9632e5c, 0x00000021 },
+ { 0x0000000071c28039, 0x000001cd },
+ { 0x000000000120a844, 0x0000b885 },
+ { 0x0000000000e54c0a, 0x000074b1 },
+ { 0x00000000001a7bb3, 0x00072331 },
+ { 0x00000000000397ad, 0x0002c61b },
+ { 0x000000000000141e, 0x06ea2e89 },
+ { 0x000000000000010a, 0xab002ad7 },
+ }, {
+ { 0x0000017949e37538, 0x00000001 },
+ { 0x0000001b62441f37, 0x00000055 },
+ { 0x0000000694a3391d, 0x00000085 },
+ { 0x0000000010b2a5d2, 0x0000a753 },
+ { 0x000000000d4398ff, 0x00001ef9 },
+ { 0x0000000001882ec6, 0x0005cbf9 },
+ { 0x000000000035333b, 0x0017abdf },
+ { 0x00000000000129f1, 0x0ab4520d },
+ { 0x0000000000000f6e, 0x8ac0ce9b },
+ }, {
+ { 0x000011f321a74e49, 0x00000006 },
+ { 0x0000014d8481d211, 0x0000005b },
+ { 0x0000005025cbd92d, 0x000001e3 },
+ { 0x00000000cb5e71e3, 0x000043e6 },
+ { 0x00000000a18c2ee1, 0x0000c097 },
+ { 0x0000000012a88828, 0x00036c97 },
+ { 0x000000000287f16f, 0x002c2a25 },
+ { 0x00000000000e2cc7, 0x02d581e3 },
+ { 0x000000000000bbf4, 0x1ba08c03 },
+ }, {
+ { 0x0000d8db8f72935d, 0x00000005 },
+ { 0x00000fbd5aed7a2e, 0x00000002 },
+ { 0x000003c84b6ea64a, 0x00000122 },
+ { 0x0000000998fa8829, 0x000044b7 },
+ { 0x000000079fb80b07, 0x00002e4a },
+ { 0x00000000e16b20fa, 0x0002a14a },
+ { 0x000000001e940d22, 0x00353b2e },
+ { 0x0000000000ab40ac, 0x06fba6ba },
+ { 0x000000000008debd, 0x72d98365 },
+ }, {
+ { 0x000cc3045b8fc281, 0x00000000 },
+ { 0x0000ed1f48b5c9fc, 0x00000079 },
+ { 0x000038fb9c63406a, 0x000000e1 },
+ { 0x000000909705b825, 0x00000a62 },
+ { 0x00000072db27380d, 0x0000d689 },
+ { 0x0000000d43fce827, 0x00082b09 },
+ { 0x00000001ccaba11a, 0x0037e8dd },
+ { 0x000000000a13f729, 0x0566dffd },
+ { 0x000000000085a14b, 0x23d36726 },
+ }, {
+ { 0x00eafeb9c993592b, 0x00000001 },
+ { 0x00110e5befa9a991, 0x00000048 },
+ { 0x00041947b4a1d36a, 0x000000dc },
+ { 0x00000a6679327311, 0x0000c079 },
+ { 0x00000842f488162e, 0x00002284 },
+ { 0x000000f4459740fc, 0x00084484 },
+ { 0x0000002122c47bf9, 0x002ca446 },
+ { 0x00000000b9936290, 0x004979c4 },
+ { 0x00000000099ca89d, 0x9db446bf },
+ }, {
+ { 0x1b60cece589da1d2, 0x00000001 },
+ { 0x01fcb42be1453f5b, 0x0000004f },
+ { 0x007a3f2457df0749, 0x0000013f },
+ { 0x0001363130e3ec7b, 0x000017aa },
+ { 0x0000f66745411d8a, 0x0000b063 },
+ { 0x00001c757dfab350, 0x00048863 },
+ { 0x000003dc4979c652, 0x00224ea7 },
+ { 0x000000159edc3144, 0x06409ab3 },
+ { 0x000000011eadfee3, 0xa99c48a8 },
+ },
+};
+
+static inline bool test_div64_verify(u64 quotient, u32 remainder, int i, int j)
+{
+ return (quotient == test_div64_results[i][j].quotient &&
+ remainder == test_div64_results[i][j].remainder);
+}
+
+/*
+ * This needs to be a macro, because we don't want to rely on the compiler
+ * to do constant propagation, and `do_div' may take a different path for
+ * constants, so we do want to verify that as well.
+ */
+#define test_div64_one(divident, divisor, i, j) ({ \
+ bool result = true; \
+ u64 quotient; \
+ u32 remainder; \
+ \
+ quotient = divident; \
+ remainder = do_div(quotient, divisor); \
+ if (!test_div64_verify(quotient, remainder, i, j)) { \
+ pr_err("ERROR: %016llx / %08x => %016llx,%08x\n", \
+ divident, divisor, quotient, remainder); \
+ pr_err("ERROR: expected value=> %016llx,%08x\n", \
+ test_div64_results[i][j].quotient, \
+ test_div64_results[i][j].remainder); \
+ result = false; \
+ } \
+ result; \
+})
+
+/*
+ * Run calculation for the same divisor value expressed as a constant
+ * and as a variable, so as to verify the implementation for both cases
+ * should they be handled by different code execution paths.
+ */
+static bool __init test_div64(void)
+{
+ u64 divident;
+ int i, j;
+
+ for (i = 0; i < SIZE_DIV64_DIVIDENTS; i++) {
+ divident = test_div64_dividents[i];
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_0, i, 0))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_1, i, 1))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_2, i, 2))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_3, i, 3))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_4, i, 4))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_5, i, 5))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_6, i, 6))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_7, i, 7))
+ return false;
+ if (!test_div64_one(divident, TEST_DIV64_DIVISOR_8, i, 8))
+ return false;
+ for (j = 0; j < SIZE_DIV64_DIVISORS; j++) {
+ if (!test_div64_one(divident, test_div64_divisors[j],
+ i, j))
+ return false;
+ }
+ }
+ return true;
+}
+
+static int __init test_div64_init(void)
+{
+ struct timespec64 ts, ts0, ts1;
+ int i;
+
+ pr_info("Starting 64bit/32bit division and modulo test\n");
+ ktime_get_ts64(&ts0);
+
+ for (i = 0; i < TEST_DIV64_N_ITER; i++)
+ if (!test_div64())
+ break;
+
+ ktime_get_ts64(&ts1);
+ ts = timespec64_sub(ts1, ts0);
+ pr_info("Completed 64bit/32bit division and modulo test, "
+ "%llu.%09lus elapsed\n", ts.tv_sec, ts.tv_nsec);
+
+ return 0;
+}
+
+static void __exit test_div64_exit(void)
+{
+}
+
+module_init(test_div64_init);
+module_exit(test_div64_exit);
+
+MODULE_AUTHOR("Maciej W. Rozycki <macro@orcam.me.uk>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("64bit/32bit division and modulo test module");