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Subject[tip: x86/misc] x86/csum: Improve performance of `csum_partial`
The following commit has been merged into the x86/misc branch of tip:

Commit-ID: 688eb8191b475db5acfd48634600b04fd3dda9ad
Gitweb: https://git.kernel.org/tip/688eb8191b475db5acfd48634600b04fd3dda9ad
Author: Noah Goldstein <goldstein.w.n@gmail.com>
AuthorDate: Wed, 10 May 2023 20:10:02 -05:00
Committer: Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Thu, 25 May 2023 10:55:18 -07:00

x86/csum: Improve performance of `csum_partial`

1) Add special case for len == 40 as that is the hottest value. The
nets a ~8-9% latency improvement and a ~30% throughput improvement
in the len == 40 case.

2) Use multiple accumulators in the 64-byte loop. This dramatically
improves ILP and results in up to a 40% latency/throughput
improvement (better for more iterations).

Results from benchmarking on Icelake. Times measured with rdtsc()
len lat_new lat_old r tput_new tput_old r
8 3.58 3.47 1.032 3.58 3.51 1.021
16 4.14 4.02 1.028 3.96 3.78 1.046
24 4.99 5.03 0.992 4.23 4.03 1.050
32 5.09 5.08 1.001 4.68 4.47 1.048
40 5.57 6.08 0.916 3.05 4.43 0.690
48 6.65 6.63 1.003 4.97 4.69 1.059
56 7.74 7.72 1.003 5.22 4.95 1.055
64 6.65 7.22 0.921 6.38 6.42 0.994
96 9.43 9.96 0.946 7.46 7.54 0.990
128 9.39 12.15 0.773 8.90 8.79 1.012
200 12.65 18.08 0.699 11.63 11.60 1.002
272 15.82 23.37 0.677 14.43 14.35 1.005
440 24.12 36.43 0.662 21.57 22.69 0.951
952 46.20 74.01 0.624 42.98 53.12 0.809
1024 47.12 78.24 0.602 46.36 58.83 0.788
1552 72.01 117.30 0.614 71.92 96.78 0.743
2048 93.07 153.25 0.607 93.28 137.20 0.680
2600 114.73 194.30 0.590 114.28 179.32 0.637
3608 156.34 268.41 0.582 154.97 254.02 0.610
4096 175.01 304.03 0.576 175.89 292.08 0.602

There is no such thing as a free lunch, however, and the special case
for len == 40 does add overhead to the len != 40 cases. This seems to
amount to be ~5% throughput and slightly less in terms of latency.

Testing:
Part of this change is a new kunit test. The tests check all
alignment X length pairs in [0, 64) X [0, 512).
There are three cases.
1) Precomputed random inputs/seed. The expected results where
generated use the generic implementation (which is assumed to be
non-buggy).
2) An input of all 1s. The goal of this test is to catch any case
a carry is missing.
3) An input that never carries. The goal of this test si to catch
any case of incorrectly carrying.

More exhaustive tests that test all alignment X length pairs in
[0, 8192) X [0, 8192] on random data are also available here:
https://github.com/goldsteinn/csum-reproduction

The reposity also has the code for reproducing the above benchmark
numbers.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20230511011002.935690-1-goldstein.w.n%40gmail.com
---
arch/x86/lib/csum-partial_64.c | 97 ++++++---
lib/Kconfig.debug | 17 ++-
lib/Makefile | 1 +-
lib/checksum_kunit.c | 334 ++++++++++++++++++++++++++++++++-
4 files changed, 417 insertions(+), 32 deletions(-)
create mode 100644 lib/checksum_kunit.c

diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c
index 50734a2..fe58619 100644
--- a/arch/x86/lib/csum-partial_64.c
+++ b/arch/x86/lib/csum-partial_64.c
@@ -5,22 +5,32 @@
* This file contains network checksum routines that are better done
* in an architecture-specific manner due to speed.
*/
-
+
#include <linux/compiler.h>
#include <linux/export.h>
#include <asm/checksum.h>
#include <asm/word-at-a-time.h>

-static inline unsigned short from32to16(unsigned a)
+static inline unsigned short from32to16(unsigned a)
{
- unsigned short b = a >> 16;
+ unsigned short b = a >> 16;
asm("addw %w2,%w0\n\t"
- "adcw $0,%w0\n"
+ "adcw $0,%w0\n"
: "=r" (b)
: "0" (b), "r" (a));
return b;
}

+static inline __wsum csum_tail(unsigned int result, u64 temp64, int odd)
+{
+ result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
+ if (unlikely(odd)) {
+ result = from32to16(result);
+ result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+ }
+ return (__force __wsum)result;
+}
+
/*
* Do a checksum on an arbitrary memory area.
* Returns a 32bit checksum.
@@ -47,21 +57,52 @@ __wsum csum_partial(const void *buff, int len, __wsum sum)
buff++;
}

- while (unlikely(len >= 64)) {
+ /*
+ * len == 40 is the hot case due to IPv6 headers, but annotating it likely()
+ * has noticeable negative affect on codegen for all other cases with
+ * minimal performance benefit here.
+ */
+ if (len == 40) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq 1*8(%[src]),%[res]\n\t"
"adcq 2*8(%[src]),%[res]\n\t"
"adcq 3*8(%[src]),%[res]\n\t"
"adcq 4*8(%[src]),%[res]\n\t"
- "adcq 5*8(%[src]),%[res]\n\t"
- "adcq 6*8(%[src]),%[res]\n\t"
- "adcq 7*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
- : [res] "+r" (temp64)
- : [src] "r" (buff)
- : "memory");
- buff += 64;
- len -= 64;
+ : [res] "+r"(temp64)
+ : [src] "r"(buff), "m"(*(const char(*)[40])buff));
+ return csum_tail(result, temp64, odd);
+ }
+ if (unlikely(len >= 64)) {
+ /*
+ * Extra accumulators for better ILP in the loop.
+ */
+ u64 tmp_accum, tmp_carries;
+
+ asm("xorl %k[tmp_accum],%k[tmp_accum]\n\t"
+ "xorl %k[tmp_carries],%k[tmp_carries]\n\t"
+ "subl $64, %[len]\n\t"
+ "1:\n\t"
+ "addq 0*8(%[src]),%[res]\n\t"
+ "adcq 1*8(%[src]),%[res]\n\t"
+ "adcq 2*8(%[src]),%[res]\n\t"
+ "adcq 3*8(%[src]),%[res]\n\t"
+ "adcl $0,%k[tmp_carries]\n\t"
+ "addq 4*8(%[src]),%[tmp_accum]\n\t"
+ "adcq 5*8(%[src]),%[tmp_accum]\n\t"
+ "adcq 6*8(%[src]),%[tmp_accum]\n\t"
+ "adcq 7*8(%[src]),%[tmp_accum]\n\t"
+ "adcl $0,%k[tmp_carries]\n\t"
+ "addq $64, %[src]\n\t"
+ "subl $64, %[len]\n\t"
+ "jge 1b\n\t"
+ "addq %[tmp_accum],%[res]\n\t"
+ "adcq %[tmp_carries],%[res]\n\t"
+ "adcq $0,%[res]"
+ : [tmp_accum] "=&r"(tmp_accum),
+ [tmp_carries] "=&r"(tmp_carries), [res] "+r"(temp64),
+ [len] "+r"(len), [src] "+r"(buff)
+ : "m"(*(const char *)buff));
}

if (len & 32) {
@@ -70,45 +111,37 @@ __wsum csum_partial(const void *buff, int len, __wsum sum)
"adcq 2*8(%[src]),%[res]\n\t"
"adcq 3*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
- : [res] "+r" (temp64)
- : [src] "r" (buff)
- : "memory");
+ : [res] "+r"(temp64)
+ : [src] "r"(buff), "m"(*(const char(*)[32])buff));
buff += 32;
}
if (len & 16) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq 1*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
- : [res] "+r" (temp64)
- : [src] "r" (buff)
- : "memory");
+ : [res] "+r"(temp64)
+ : [src] "r"(buff), "m"(*(const char(*)[16])buff));
buff += 16;
}
if (len & 8) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
- : [res] "+r" (temp64)
- : [src] "r" (buff)
- : "memory");
+ : [res] "+r"(temp64)
+ : [src] "r"(buff), "m"(*(const char(*)[8])buff));
buff += 8;
}
if (len & 7) {
- unsigned int shift = (8 - (len & 7)) * 8;
+ unsigned int shift = (-len << 3) & 63;
unsigned long trail;

trail = (load_unaligned_zeropad(buff) << shift) >> shift;

asm("addq %[trail],%[res]\n\t"
"adcq $0,%[res]"
- : [res] "+r" (temp64)
- : [trail] "r" (trail));
+ : [res] "+r"(temp64)
+ : [trail] "r"(trail));
}
- result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
- if (unlikely(odd)) {
- result = from32to16(result);
- result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
- }
- return (__force __wsum)result;
+ return csum_tail(result, temp64, odd);
}
EXPORT_SYMBOL(csum_partial);

@@ -118,6 +151,6 @@ EXPORT_SYMBOL(csum_partial);
*/
__sum16 ip_compute_csum(const void *buff, int len)
{
- return csum_fold(csum_partial(buff,len,0));
+ return csum_fold(csum_partial(buff, len, 0));
}
EXPORT_SYMBOL(ip_compute_csum);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ce51d4d..f2d6e9d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2453,6 +2453,23 @@ config BITFIELD_KUNIT

If unsure, say N.

+config CHECKSUM_KUNIT
+ tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ Enable this option to test the checksum functions at boot.
+
+ KUnit tests run during boot and output the results to the debug log
+ in TAP format (http://testanything.org/). Only useful for kernel devs
+ running the KUnit test harness, and not intended for inclusion into a
+ production build.
+
+ For more information on KUnit and unit tests in general please refer
+ to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+ If unsure, say N.
+
config HASH_KUNIT_TEST
tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
depends on KUNIT
diff --git a/lib/Makefile b/lib/Makefile
index 876fcde..cd37ec1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -377,6 +377,7 @@ obj-$(CONFIG_PLDMFW) += pldmfw/
# KUnit tests
CFLAGS_bitfield_kunit.o := $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_BITFIELD_KUNIT) += bitfield_kunit.o
+obj-$(CONFIG_CHECKSUM_KUNIT) += checksum_kunit.o
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
obj-$(CONFIG_HASHTABLE_KUNIT_TEST) += hashtable_test.o
obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
diff --git a/lib/checksum_kunit.c b/lib/checksum_kunit.c
new file mode 100644
index 0000000..ace3c47
--- /dev/null
+++ b/lib/checksum_kunit.c
@@ -0,0 +1,334 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Test cases csum_partial and csum_fold
+ */
+
+#include <kunit/test.h>
+#include <asm/checksum.h>
+
+#define MAX_LEN 512
+#define MAX_ALIGN 64
+#define TEST_BUFLEN (MAX_LEN + MAX_ALIGN)
+
+static const __wsum random_init_sum = 0x2847aab;
+static const u8 random_buf[] = {
+ 0xac, 0xd7, 0x76, 0x69, 0x6e, 0xf2, 0x93, 0x2c, 0x1f, 0xe0, 0xde, 0x86,
+ 0x8f, 0x54, 0x33, 0x90, 0x95, 0xbf, 0xff, 0xb9, 0xea, 0x62, 0x6e, 0xb5,
+ 0xd3, 0x4f, 0xf5, 0x60, 0x50, 0x5c, 0xc7, 0xfa, 0x6d, 0x1a, 0xc7, 0xf0,
+ 0xd2, 0x2c, 0x12, 0x3d, 0x88, 0xe3, 0x14, 0x21, 0xb1, 0x5e, 0x45, 0x31,
+ 0xa2, 0x85, 0x36, 0x76, 0xba, 0xd8, 0xad, 0xbb, 0x9e, 0x49, 0x8f, 0xf7,
+ 0xce, 0xea, 0xef, 0xca, 0x2c, 0x29, 0xf7, 0x15, 0x5c, 0x1d, 0x4d, 0x09,
+ 0x1f, 0xe2, 0x14, 0x31, 0x8c, 0x07, 0x57, 0x23, 0x1f, 0x6f, 0x03, 0xe1,
+ 0x93, 0x19, 0x53, 0x03, 0x45, 0x49, 0x9a, 0x3b, 0x8e, 0x0c, 0x12, 0x5d,
+ 0x8a, 0xb8, 0x9b, 0x8c, 0x9a, 0x03, 0xe5, 0xa2, 0x43, 0xd2, 0x3b, 0x4e,
+ 0x7e, 0x30, 0x3c, 0x22, 0x2d, 0xc5, 0xfc, 0x9e, 0xdb, 0xc6, 0xf9, 0x69,
+ 0x12, 0x39, 0x1f, 0xa0, 0x11, 0x0c, 0x3f, 0xf5, 0x53, 0xc9, 0x30, 0xfb,
+ 0xb0, 0xdd, 0x21, 0x1d, 0x34, 0xe2, 0x65, 0x30, 0xf1, 0xe8, 0x1b, 0xe7,
+ 0x55, 0x0d, 0xeb, 0xbd, 0xcc, 0x9d, 0x24, 0xa4, 0xad, 0xa7, 0x93, 0x47,
+ 0x19, 0x2e, 0xc4, 0x5c, 0x3b, 0xc7, 0x6d, 0x95, 0x0c, 0x47, 0x60, 0xaf,
+ 0x5b, 0x47, 0xee, 0xdc, 0x31, 0x31, 0x14, 0x12, 0x7e, 0x9e, 0x45, 0xb1,
+ 0xc1, 0x69, 0x4b, 0x84, 0xfc, 0x88, 0xc1, 0x9e, 0x46, 0xb4, 0xc2, 0x25,
+ 0xc5, 0x6c, 0x4c, 0x22, 0x58, 0x5c, 0xbe, 0xff, 0xea, 0x88, 0x88, 0x7a,
+ 0xcb, 0x1c, 0x5d, 0x63, 0xa1, 0xf2, 0x33, 0x0c, 0xa2, 0x16, 0x0b, 0x6e,
+ 0x2b, 0x79, 0x58, 0xf7, 0xac, 0xd3, 0x6a, 0x3f, 0x81, 0x57, 0x48, 0x45,
+ 0xe3, 0x7c, 0xdc, 0xd6, 0x34, 0x7e, 0xe6, 0x73, 0xfa, 0xcb, 0x31, 0x18,
+ 0xa9, 0x0b, 0xee, 0x6b, 0x99, 0xb9, 0x2d, 0xde, 0x22, 0x0e, 0x71, 0x57,
+ 0x0e, 0x9b, 0x11, 0xd1, 0x15, 0x41, 0xd0, 0x6b, 0x50, 0x8a, 0x23, 0x64,
+ 0xe3, 0x9c, 0xb3, 0x55, 0x09, 0xe9, 0x32, 0x67, 0xf9, 0xe0, 0x73, 0xf1,
+ 0x60, 0x66, 0x0b, 0x88, 0x79, 0x8d, 0x4b, 0x52, 0x83, 0x20, 0x26, 0x78,
+ 0x49, 0x27, 0xe7, 0x3e, 0x29, 0xa8, 0x18, 0x82, 0x41, 0xdd, 0x1e, 0xcc,
+ 0x3b, 0xc4, 0x65, 0xd1, 0x21, 0x40, 0x72, 0xb2, 0x87, 0x5e, 0x16, 0x10,
+ 0x80, 0x3f, 0x4b, 0x58, 0x1c, 0xc2, 0x79, 0x20, 0xf0, 0xe0, 0x80, 0xd3,
+ 0x52, 0xa5, 0x19, 0x6e, 0x47, 0x90, 0x08, 0xf5, 0x50, 0xe2, 0xd6, 0xae,
+ 0xe9, 0x2e, 0xdc, 0xd5, 0xb4, 0x90, 0x1f, 0x79, 0x49, 0x82, 0x21, 0x84,
+ 0xa0, 0xb5, 0x2f, 0xff, 0x30, 0x71, 0xed, 0x80, 0x68, 0xb1, 0x6d, 0xef,
+ 0xf6, 0xcf, 0xb8, 0x41, 0x79, 0xf5, 0x01, 0xbc, 0x0c, 0x9b, 0x0e, 0x06,
+ 0xf3, 0xb0, 0xbb, 0x97, 0xb8, 0xb1, 0xfd, 0x51, 0x4e, 0xef, 0x0a, 0x3d,
+ 0x7a, 0x3d, 0xbd, 0x61, 0x00, 0xa2, 0xb3, 0xf0, 0x1d, 0x77, 0x7b, 0x6c,
+ 0x01, 0x61, 0xa5, 0xa3, 0xdb, 0xd5, 0xd5, 0xf4, 0xb5, 0x28, 0x9f, 0x0a,
+ 0xa3, 0x82, 0x5f, 0x4b, 0x40, 0x0f, 0x05, 0x0e, 0x78, 0xed, 0xbf, 0x17,
+ 0xf6, 0x5a, 0x8a, 0x7d, 0xf9, 0x45, 0xc1, 0xd7, 0x1b, 0x9d, 0x6c, 0x07,
+ 0x88, 0xf3, 0xbc, 0xf1, 0xea, 0x28, 0x1f, 0xb8, 0x7a, 0x60, 0x3c, 0xce,
+ 0x3e, 0x50, 0xb2, 0x0b, 0xcf, 0xe5, 0x08, 0x1f, 0x48, 0x04, 0xf9, 0x35,
+ 0x29, 0x15, 0xbe, 0x82, 0x96, 0xc2, 0x55, 0x04, 0x6c, 0x19, 0x45, 0x29,
+ 0x0b, 0xb6, 0x49, 0x12, 0xfb, 0x8d, 0x1b, 0x75, 0x8b, 0xd9, 0x6a, 0x5c,
+ 0xbe, 0x46, 0x2b, 0x41, 0xfe, 0x21, 0xad, 0x1f, 0x75, 0xe7, 0x90, 0x3d,
+ 0xe1, 0xdf, 0x4b, 0xe1, 0x81, 0xe2, 0x17, 0x02, 0x7b, 0x58, 0x8b, 0x92,
+ 0x1a, 0xac, 0x46, 0xdd, 0x2e, 0xce, 0x40, 0x09
+};
+static const __sum16 expected_results[] = {
+ 0x82d0, 0x8224, 0xab23, 0xaaad, 0x41ad, 0x413f, 0x4f3e, 0x4eab, 0x22ab,
+ 0x228c, 0x428b, 0x41ad, 0xbbac, 0xbb1d, 0x671d, 0x66ea, 0xd6e9, 0xd654,
+ 0x1754, 0x1655, 0x5d54, 0x5c6a, 0xfa69, 0xf9fb, 0x44fb, 0x4428, 0xf527,
+ 0xf432, 0x9432, 0x93e2, 0x37e2, 0x371b, 0x3d1a, 0x3cad, 0x22ad, 0x21e6,
+ 0x31e5, 0x3113, 0x0513, 0x0501, 0xc800, 0xc778, 0xe477, 0xe463, 0xc363,
+ 0xc2b2, 0x64b2, 0x646d, 0x336d, 0x32cb, 0xadca, 0xad94, 0x3794, 0x36da,
+ 0x5ed9, 0x5e2c, 0xa32b, 0xa28d, 0x598d, 0x58fe, 0x61fd, 0x612f, 0x772e,
+ 0x763f, 0xac3e, 0xac12, 0x8312, 0x821b, 0x6d1b, 0x6cbf, 0x4fbf, 0x4f72,
+ 0x4672, 0x4653, 0x6452, 0x643e, 0x333e, 0x32b2, 0x2bb2, 0x2b5b, 0x085b,
+ 0x083c, 0x993b, 0x9938, 0xb837, 0xb7a4, 0x9ea4, 0x9e51, 0x9b51, 0x9b0c,
+ 0x520c, 0x5172, 0x1672, 0x15e4, 0x09e4, 0x09d2, 0xacd1, 0xac47, 0xf446,
+ 0xf3ab, 0x67ab, 0x6711, 0x6411, 0x632c, 0xc12b, 0xc0e8, 0xeee7, 0xeeac,
+ 0xa0ac, 0xa02e, 0x702e, 0x6ff2, 0x4df2, 0x4dc5, 0x88c4, 0x87c8, 0xe9c7,
+ 0xe8ec, 0x22ec, 0x21f3, 0xb8f2, 0xb8e0, 0x7fe0, 0x7fc1, 0xdfc0, 0xdfaf,
+ 0xd3af, 0xd370, 0xde6f, 0xde1c, 0x151c, 0x14ec, 0x19eb, 0x193b, 0x3c3a,
+ 0x3c19, 0x1f19, 0x1ee5, 0x3ce4, 0x3c7f, 0x0c7f, 0x0b8e, 0x238d, 0x2372,
+ 0x3c71, 0x3c1c, 0x2f1c, 0x2e31, 0x7130, 0x7064, 0xd363, 0xd33f, 0x2f3f,
+ 0x2e92, 0x8791, 0x86fe, 0x3ffe, 0x3fe5, 0x11e5, 0x1121, 0xb520, 0xb4e5,
+ 0xede4, 0xed77, 0x5877, 0x586b, 0x116b, 0x110b, 0x620a, 0x61af, 0x1aaf,
+ 0x19c1, 0x3dc0, 0x3d8f, 0x0c8f, 0x0c7b, 0xfa7a, 0xf9fc, 0x5bfc, 0x5bb7,
+ 0xaab6, 0xa9f5, 0x40f5, 0x40aa, 0xbca9, 0xbbad, 0x33ad, 0x32ec, 0x94eb,
+ 0x94a5, 0xe0a4, 0xdfe2, 0xbae2, 0xba1d, 0x4e1d, 0x4dd1, 0x2bd1, 0x2b79,
+ 0xcf78, 0xceba, 0xcfb9, 0xcecf, 0x46cf, 0x4647, 0xcc46, 0xcb7b, 0xaf7b,
+ 0xaf1e, 0x4c1e, 0x4b7d, 0x597c, 0x5949, 0x4d49, 0x4ca7, 0x36a7, 0x369c,
+ 0xc89b, 0xc870, 0x4f70, 0x4f18, 0x5817, 0x576b, 0x846a, 0x8400, 0x4500,
+ 0x447f, 0xed7e, 0xed36, 0xa836, 0xa753, 0x2b53, 0x2a77, 0x5476, 0x5442,
+ 0xd641, 0xd55b, 0x625b, 0x6161, 0x9660, 0x962f, 0x7e2f, 0x7d86, 0x7286,
+ 0x7198, 0x0698, 0x05ff, 0x4cfe, 0x4cd1, 0x6ed0, 0x6eae, 0x60ae, 0x603d,
+ 0x093d, 0x092f, 0x6e2e, 0x6e1d, 0x9d1c, 0x9d07, 0x5c07, 0x5b37, 0xf036,
+ 0xefe6, 0x65e6, 0x65c3, 0x01c3, 0x00e0, 0x64df, 0x642c, 0x0f2c, 0x0f23,
+ 0x2622, 0x25f0, 0xbeef, 0xbdf6, 0xddf5, 0xdd82, 0xec81, 0xec21, 0x8621,
+ 0x8616, 0xfe15, 0xfd9c, 0x709c, 0x7051, 0x1e51, 0x1dce, 0xfdcd, 0xfda7,
+ 0x85a7, 0x855e, 0x5e5e, 0x5d77, 0x1f77, 0x1f4e, 0x774d, 0x7735, 0xf534,
+ 0xf4f3, 0x17f3, 0x17d5, 0x4bd4, 0x4b99, 0x8798, 0x8733, 0xb632, 0xb611,
+ 0x7611, 0x759f, 0xc39e, 0xc317, 0x6517, 0x6501, 0x5501, 0x5481, 0x1581,
+ 0x1536, 0xbd35, 0xbd19, 0xfb18, 0xfa9f, 0xda9f, 0xd9af, 0xf9ae, 0xf92e,
+ 0x262e, 0x25dc, 0x80db, 0x80c2, 0x12c2, 0x127b, 0x827a, 0x8272, 0x8d71,
+ 0x8d21, 0xab20, 0xaa4a, 0xfc49, 0xfb60, 0xcd60, 0xcc84, 0xf783, 0xf6cf,
+ 0x66cf, 0x66b0, 0xedaf, 0xed66, 0x6b66, 0x6b45, 0xe744, 0xe6a4, 0x31a4,
+ 0x3175, 0x3274, 0x3244, 0xc143, 0xc056, 0x4056, 0x3fee, 0x8eed, 0x8e80,
+ 0x9f7f, 0x9e89, 0xcf88, 0xced0, 0x8dd0, 0x8d57, 0x9856, 0x9855, 0xdc54,
+ 0xdc48, 0x4148, 0x413a, 0x3b3a, 0x3a47, 0x8a46, 0x898b, 0xf28a, 0xf1d2,
+ 0x40d2, 0x3fd5, 0xeed4, 0xee86, 0xff85, 0xff7b, 0xc27b, 0xc201, 0x8501,
+ 0x8444, 0x2344, 0x2344, 0x8143, 0x8090, 0x908f, 0x9072, 0x1972, 0x18f7,
+ 0xacf6, 0xacf5, 0x4bf5, 0x4b50, 0xa84f, 0xa774, 0xd273, 0xd19e, 0xdd9d,
+ 0xdce8, 0xb4e8, 0xb449, 0xaa49, 0xa9a6, 0x27a6, 0x2747, 0xdc46, 0xdc06,
+ 0xcd06, 0xcd01, 0xbf01, 0xbe89, 0xd188, 0xd0c9, 0xb9c9, 0xb8d3, 0x5ed3,
+ 0x5e49, 0xe148, 0xe04f, 0x9b4f, 0x9a8e, 0xc38d, 0xc372, 0x2672, 0x2606,
+ 0x1f06, 0x1e7e, 0x2b7d, 0x2ac1, 0x39c0, 0x38d6, 0x10d6, 0x10b7, 0x58b6,
+ 0x583c, 0xf83b, 0xf7ff, 0x29ff, 0x29c1, 0xd9c0, 0xd90e, 0xce0e, 0xcd3f,
+ 0xe83e, 0xe836, 0xc936, 0xc8ee, 0xc4ee, 0xc3f5, 0x8ef5, 0x8ecc, 0x79cc,
+ 0x790e, 0xf70d, 0xf677, 0x3477, 0x3422, 0x3022, 0x2fb6, 0x16b6, 0x1671,
+ 0xed70, 0xed65, 0x3765, 0x371c, 0x251c, 0x2421, 0x9720, 0x9705, 0x2205,
+ 0x217a, 0x4879, 0x480f, 0xec0e, 0xeb50, 0xa550, 0xa525, 0x6425, 0x6327,
+ 0x4227, 0x417a, 0x227a, 0x2205, 0x3b04, 0x3a74, 0xfd73, 0xfc92, 0x1d92,
+ 0x1d47, 0x3c46, 0x3bc5, 0x59c4, 0x59ad, 0x57ad, 0x5732, 0xff31, 0xfea6,
+ 0x6ca6, 0x6c8c, 0xc08b, 0xc045, 0xe344, 0xe316, 0x1516, 0x14d6,
+};
+static const __wsum init_sums_no_overflow[] = {
+ 0xffffffff, 0xfffffffb, 0xfffffbfb, 0xfffffbf7, 0xfffff7f7, 0xfffff7f3,
+ 0xfffff3f3, 0xfffff3ef, 0xffffefef, 0xffffefeb, 0xffffebeb, 0xffffebe7,
+ 0xffffe7e7, 0xffffe7e3, 0xffffe3e3, 0xffffe3df, 0xffffdfdf, 0xffffdfdb,
+ 0xffffdbdb, 0xffffdbd7, 0xffffd7d7, 0xffffd7d3, 0xffffd3d3, 0xffffd3cf,
+ 0xffffcfcf, 0xffffcfcb, 0xffffcbcb, 0xffffcbc7, 0xffffc7c7, 0xffffc7c3,
+ 0xffffc3c3, 0xffffc3bf, 0xffffbfbf, 0xffffbfbb, 0xffffbbbb, 0xffffbbb7,
+ 0xffffb7b7, 0xffffb7b3, 0xffffb3b3, 0xffffb3af, 0xffffafaf, 0xffffafab,
+ 0xffffabab, 0xffffaba7, 0xffffa7a7, 0xffffa7a3, 0xffffa3a3, 0xffffa39f,
+ 0xffff9f9f, 0xffff9f9b, 0xffff9b9b, 0xffff9b97, 0xffff9797, 0xffff9793,
+ 0xffff9393, 0xffff938f, 0xffff8f8f, 0xffff8f8b, 0xffff8b8b, 0xffff8b87,
+ 0xffff8787, 0xffff8783, 0xffff8383, 0xffff837f, 0xffff7f7f, 0xffff7f7b,
+ 0xffff7b7b, 0xffff7b77, 0xffff7777, 0xffff7773, 0xffff7373, 0xffff736f,
+ 0xffff6f6f, 0xffff6f6b, 0xffff6b6b, 0xffff6b67, 0xffff6767, 0xffff6763,
+ 0xffff6363, 0xffff635f, 0xffff5f5f, 0xffff5f5b, 0xffff5b5b, 0xffff5b57,
+ 0xffff5757, 0xffff5753, 0xffff5353, 0xffff534f, 0xffff4f4f, 0xffff4f4b,
+ 0xffff4b4b, 0xffff4b47, 0xffff4747, 0xffff4743, 0xffff4343, 0xffff433f,
+ 0xffff3f3f, 0xffff3f3b, 0xffff3b3b, 0xffff3b37, 0xffff3737, 0xffff3733,
+ 0xffff3333, 0xffff332f, 0xffff2f2f, 0xffff2f2b, 0xffff2b2b, 0xffff2b27,
+ 0xffff2727, 0xffff2723, 0xffff2323, 0xffff231f, 0xffff1f1f, 0xffff1f1b,
+ 0xffff1b1b, 0xffff1b17, 0xffff1717, 0xffff1713, 0xffff1313, 0xffff130f,
+ 0xffff0f0f, 0xffff0f0b, 0xffff0b0b, 0xffff0b07, 0xffff0707, 0xffff0703,
+ 0xffff0303, 0xffff02ff, 0xfffffefe, 0xfffffefa, 0xfffffafa, 0xfffffaf6,
+ 0xfffff6f6, 0xfffff6f2, 0xfffff2f2, 0xfffff2ee, 0xffffeeee, 0xffffeeea,
+ 0xffffeaea, 0xffffeae6, 0xffffe6e6, 0xffffe6e2, 0xffffe2e2, 0xffffe2de,
+ 0xffffdede, 0xffffdeda, 0xffffdada, 0xffffdad6, 0xffffd6d6, 0xffffd6d2,
+ 0xffffd2d2, 0xffffd2ce, 0xffffcece, 0xffffceca, 0xffffcaca, 0xffffcac6,
+ 0xffffc6c6, 0xffffc6c2, 0xffffc2c2, 0xffffc2be, 0xffffbebe, 0xffffbeba,
+ 0xffffbaba, 0xffffbab6, 0xffffb6b6, 0xffffb6b2, 0xffffb2b2, 0xffffb2ae,
+ 0xffffaeae, 0xffffaeaa, 0xffffaaaa, 0xffffaaa6, 0xffffa6a6, 0xffffa6a2,
+ 0xffffa2a2, 0xffffa29e, 0xffff9e9e, 0xffff9e9a, 0xffff9a9a, 0xffff9a96,
+ 0xffff9696, 0xffff9692, 0xffff9292, 0xffff928e, 0xffff8e8e, 0xffff8e8a,
+ 0xffff8a8a, 0xffff8a86, 0xffff8686, 0xffff8682, 0xffff8282, 0xffff827e,
+ 0xffff7e7e, 0xffff7e7a, 0xffff7a7a, 0xffff7a76, 0xffff7676, 0xffff7672,
+ 0xffff7272, 0xffff726e, 0xffff6e6e, 0xffff6e6a, 0xffff6a6a, 0xffff6a66,
+ 0xffff6666, 0xffff6662, 0xffff6262, 0xffff625e, 0xffff5e5e, 0xffff5e5a,
+ 0xffff5a5a, 0xffff5a56, 0xffff5656, 0xffff5652, 0xffff5252, 0xffff524e,
+ 0xffff4e4e, 0xffff4e4a, 0xffff4a4a, 0xffff4a46, 0xffff4646, 0xffff4642,
+ 0xffff4242, 0xffff423e, 0xffff3e3e, 0xffff3e3a, 0xffff3a3a, 0xffff3a36,
+ 0xffff3636, 0xffff3632, 0xffff3232, 0xffff322e, 0xffff2e2e, 0xffff2e2a,
+ 0xffff2a2a, 0xffff2a26, 0xffff2626, 0xffff2622, 0xffff2222, 0xffff221e,
+ 0xffff1e1e, 0xffff1e1a, 0xffff1a1a, 0xffff1a16, 0xffff1616, 0xffff1612,
+ 0xffff1212, 0xffff120e, 0xffff0e0e, 0xffff0e0a, 0xffff0a0a, 0xffff0a06,
+ 0xffff0606, 0xffff0602, 0xffff0202, 0xffff01fe, 0xfffffdfd, 0xfffffdf9,
+ 0xfffff9f9, 0xfffff9f5, 0xfffff5f5, 0xfffff5f1, 0xfffff1f1, 0xfffff1ed,
+ 0xffffeded, 0xffffede9, 0xffffe9e9, 0xffffe9e5, 0xffffe5e5, 0xffffe5e1,
+ 0xffffe1e1, 0xffffe1dd, 0xffffdddd, 0xffffddd9, 0xffffd9d9, 0xffffd9d5,
+ 0xffffd5d5, 0xffffd5d1, 0xffffd1d1, 0xffffd1cd, 0xffffcdcd, 0xffffcdc9,
+ 0xffffc9c9, 0xffffc9c5, 0xffffc5c5, 0xffffc5c1, 0xffffc1c1, 0xffffc1bd,
+ 0xffffbdbd, 0xffffbdb9, 0xffffb9b9, 0xffffb9b5, 0xffffb5b5, 0xffffb5b1,
+ 0xffffb1b1, 0xffffb1ad, 0xffffadad, 0xffffada9, 0xffffa9a9, 0xffffa9a5,
+ 0xffffa5a5, 0xffffa5a1, 0xffffa1a1, 0xffffa19d, 0xffff9d9d, 0xffff9d99,
+ 0xffff9999, 0xffff9995, 0xffff9595, 0xffff9591, 0xffff9191, 0xffff918d,
+ 0xffff8d8d, 0xffff8d89, 0xffff8989, 0xffff8985, 0xffff8585, 0xffff8581,
+ 0xffff8181, 0xffff817d, 0xffff7d7d, 0xffff7d79, 0xffff7979, 0xffff7975,
+ 0xffff7575, 0xffff7571, 0xffff7171, 0xffff716d, 0xffff6d6d, 0xffff6d69,
+ 0xffff6969, 0xffff6965, 0xffff6565, 0xffff6561, 0xffff6161, 0xffff615d,
+ 0xffff5d5d, 0xffff5d59, 0xffff5959, 0xffff5955, 0xffff5555, 0xffff5551,
+ 0xffff5151, 0xffff514d, 0xffff4d4d, 0xffff4d49, 0xffff4949, 0xffff4945,
+ 0xffff4545, 0xffff4541, 0xffff4141, 0xffff413d, 0xffff3d3d, 0xffff3d39,
+ 0xffff3939, 0xffff3935, 0xffff3535, 0xffff3531, 0xffff3131, 0xffff312d,
+ 0xffff2d2d, 0xffff2d29, 0xffff2929, 0xffff2925, 0xffff2525, 0xffff2521,
+ 0xffff2121, 0xffff211d, 0xffff1d1d, 0xffff1d19, 0xffff1919, 0xffff1915,
+ 0xffff1515, 0xffff1511, 0xffff1111, 0xffff110d, 0xffff0d0d, 0xffff0d09,
+ 0xffff0909, 0xffff0905, 0xffff0505, 0xffff0501, 0xffff0101, 0xffff00fd,
+ 0xfffffcfc, 0xfffffcf8, 0xfffff8f8, 0xfffff8f4, 0xfffff4f4, 0xfffff4f0,
+ 0xfffff0f0, 0xfffff0ec, 0xffffecec, 0xffffece8, 0xffffe8e8, 0xffffe8e4,
+ 0xffffe4e4, 0xffffe4e0, 0xffffe0e0, 0xffffe0dc, 0xffffdcdc, 0xffffdcd8,
+ 0xffffd8d8, 0xffffd8d4, 0xffffd4d4, 0xffffd4d0, 0xffffd0d0, 0xffffd0cc,
+ 0xffffcccc, 0xffffccc8, 0xffffc8c8, 0xffffc8c4, 0xffffc4c4, 0xffffc4c0,
+ 0xffffc0c0, 0xffffc0bc, 0xffffbcbc, 0xffffbcb8, 0xffffb8b8, 0xffffb8b4,
+ 0xffffb4b4, 0xffffb4b0, 0xffffb0b0, 0xffffb0ac, 0xffffacac, 0xffffaca8,
+ 0xffffa8a8, 0xffffa8a4, 0xffffa4a4, 0xffffa4a0, 0xffffa0a0, 0xffffa09c,
+ 0xffff9c9c, 0xffff9c98, 0xffff9898, 0xffff9894, 0xffff9494, 0xffff9490,
+ 0xffff9090, 0xffff908c, 0xffff8c8c, 0xffff8c88, 0xffff8888, 0xffff8884,
+ 0xffff8484, 0xffff8480, 0xffff8080, 0xffff807c, 0xffff7c7c, 0xffff7c78,
+ 0xffff7878, 0xffff7874, 0xffff7474, 0xffff7470, 0xffff7070, 0xffff706c,
+ 0xffff6c6c, 0xffff6c68, 0xffff6868, 0xffff6864, 0xffff6464, 0xffff6460,
+ 0xffff6060, 0xffff605c, 0xffff5c5c, 0xffff5c58, 0xffff5858, 0xffff5854,
+ 0xffff5454, 0xffff5450, 0xffff5050, 0xffff504c, 0xffff4c4c, 0xffff4c48,
+ 0xffff4848, 0xffff4844, 0xffff4444, 0xffff4440, 0xffff4040, 0xffff403c,
+ 0xffff3c3c, 0xffff3c38, 0xffff3838, 0xffff3834, 0xffff3434, 0xffff3430,
+ 0xffff3030, 0xffff302c, 0xffff2c2c, 0xffff2c28, 0xffff2828, 0xffff2824,
+ 0xffff2424, 0xffff2420, 0xffff2020, 0xffff201c, 0xffff1c1c, 0xffff1c18,
+ 0xffff1818, 0xffff1814, 0xffff1414, 0xffff1410, 0xffff1010, 0xffff100c,
+ 0xffff0c0c, 0xffff0c08, 0xffff0808, 0xffff0804, 0xffff0404, 0xffff0400,
+ 0xffff0000, 0xfffffffb,
+};
+
+static u8 tmp_buf[TEST_BUFLEN];
+
+#define full_csum(buff, len, sum) csum_fold(csum_partial(buff, len, sum))
+
+#define CHECK_EQ(lhs, rhs) KUNIT_ASSERT_EQ(test, lhs, rhs)
+
+static void assert_setup_correct(struct kunit *test)
+{
+ CHECK_EQ(sizeof(random_buf) / sizeof(random_buf[0]), MAX_LEN);
+ CHECK_EQ(sizeof(expected_results) / sizeof(expected_results[0]),
+ MAX_LEN);
+ CHECK_EQ(sizeof(init_sums_no_overflow) /
+ sizeof(init_sums_no_overflow[0]),
+ MAX_LEN);
+}
+
+/*
+ * Test with randomized input (pre determined random with known results).
+ */
+static void test_csum_fixed_random_inputs(struct kunit *test)
+{
+ int len, align;
+ __wsum result, expec, sum;
+
+ assert_setup_correct(test);
+ for (align = 0; align < TEST_BUFLEN; ++align) {
+ memcpy(&tmp_buf[align], random_buf,
+ min(MAX_LEN, TEST_BUFLEN - align));
+ for (len = 0; len < MAX_LEN && (align + len) < TEST_BUFLEN;
+ ++len) {
+ /*
+ * Test the precomputed random input.
+ */
+ sum = random_init_sum;
+ result = full_csum(&tmp_buf[align], len, sum);
+ expec = expected_results[len];
+ CHECK_EQ(result, expec);
+ }
+ }
+}
+
+/*
+ * All ones input test. If there are any missing carry operations, it fails.
+ */
+static void test_csum_all_carry_inputs(struct kunit *test)
+{
+ int len, align;
+ __wsum result, expec, sum;
+
+ assert_setup_correct(test);
+ memset(tmp_buf, 0xff, TEST_BUFLEN);
+ for (align = 0; align < TEST_BUFLEN; ++align) {
+ for (len = 0; len < MAX_LEN && (align + len) < TEST_BUFLEN;
+ ++len) {
+ /*
+ * All carries from input and initial sum.
+ */
+ sum = 0xffffffff;
+ result = full_csum(&tmp_buf[align], len, sum);
+ expec = (len & 1) ? 0xff00 : 0;
+ CHECK_EQ(result, expec);
+
+ /*
+ * All carries from input.
+ */
+ sum = 0;
+ result = full_csum(&tmp_buf[align], len, sum);
+ if (len & 1)
+ expec = 0xff00;
+ else if (len)
+ expec = 0;
+ else
+ expec = 0xffff;
+ CHECK_EQ(result, expec);
+ }
+ }
+}
+
+/*
+ * Test with input that alone doesn't cause any carries. By selecting the
+ * maximum initial sum, this allows us to test that there are no carries
+ * where there shouldn't be.
+ */
+static void test_csum_no_carry_inputs(struct kunit *test)
+{
+ int len, align;
+ __wsum result, expec, sum;
+
+ assert_setup_correct(test);
+ memset(tmp_buf, 0x4, TEST_BUFLEN);
+ for (align = 0; align < TEST_BUFLEN; ++align) {
+ for (len = 0; len < MAX_LEN && (align + len) < TEST_BUFLEN;
+ ++len) {
+ /*
+ * Expect no carries.
+ */
+ sum = init_sums_no_overflow[len];
+ result = full_csum(&tmp_buf[align], len, sum);
+ expec = 0;
+ CHECK_EQ(result, expec);
+
+ /*
+ * Expect one carry.
+ */
+ sum = init_sums_no_overflow[len] + 1;
+ result = full_csum(&tmp_buf[align], len, sum);
+ expec = len ? 0xfffe : 0xffff;
+ CHECK_EQ(result, expec);
+ }
+ }
+}
+
+static struct kunit_case __refdata checksum_test_cases[] = {
+ KUNIT_CASE(test_csum_fixed_random_inputs),
+ KUNIT_CASE(test_csum_all_carry_inputs),
+ KUNIT_CASE(test_csum_no_carry_inputs),
+ {}
+};
+
+static struct kunit_suite checksum_test_suite = {
+ .name = "checksum",
+ .test_cases = checksum_test_cases,
+};
+
+kunit_test_suites(&checksum_test_suite);
+
+MODULE_AUTHOR("Noah Goldstein <goldstein.w.n@gmail.com>");
+MODULE_LICENSE("GPL");
\
 
 \ /
  Last update: 2023-05-25 22:39    [W:0.239 / U:0.088 seconds]
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