Commit 5d042707 authored by Vinicius Peixoto's avatar Vinicius Peixoto Committed by Andrew Morton
Browse files

lib/crc16_kunit.c: add KUnit tests for crc16 

Add Kunit tests for the kernel's implementation of the standard CRC-16
algorithm (<linux/crc16.h>).  The test data consists of 100
randomly-generated test cases, validated against a naive CRC-16
implementation.

This test follows roughly the same logic as lib/crc32test.c, but without
the performance measurements.

Link: https://lkml.kernel.org/r/20241012-crc16-kunit-v3-1-0ca75cb58ca9@lkcamp.dev


Signed-off-by: default avatarVinicius Peixoto <vpeixoto@lkcamp.dev>
Co-developed-by: default avatarEnzo Bertoloti <ebertoloti@lkcamp.dev>
Signed-off-by: default avatarEnzo Bertoloti <ebertoloti@lkcamp.dev>
Co-developed-by: default avatarFabricio Gasperin <fgasperin@lkcamp.dev>
Signed-off-by: default avatarFabricio Gasperin <fgasperin@lkcamp.dev>
Suggested-by: default avatarDavid Laight <David.Laight@ACULAB.COM>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a9d38bcd

lib/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -2850,6 +2850,15 @@ config USERCOPY_KUNIT_TEST 
	  on the copy_to/from_user infrastructure, making sure basic

	  user/kernel boundary testing is working.



config CRC16_KUNIT_TEST

	tristate "KUnit tests for CRC16"

	depends on KUNIT

	default KUNIT_ALL_TESTS

	select CRC16

	help

	  Enable this option to run unit tests for the kernel's CRC16

	  implementation (<linux/crc16.h>).



config TEST_UDELAY

	tristate "udelay test driver"

	help

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -389,6 +389,7 @@ CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN) 
obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o

obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o

obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o

obj-$(CONFIG_CRC16_KUNIT_TEST) += crc16_kunit.o



obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o

lib/crc16_kunit.c

0 → 100644
+155 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * KUnits tests for CRC16.

 *

 * Copyright (C) 2024, LKCAMP

 * Author: Vinicius Peixoto <vpeixoto@lkcamp.dev>

 * Author: Fabricio Gasperin <fgasperin@lkcamp.dev>

 * Author: Enzo Bertoloti <ebertoloti@lkcamp.dev>

 */

#include <kunit/test.h>

#include <linux/crc16.h>

#include <linux/prandom.h>



#define CRC16_KUNIT_DATA_SIZE 4096

#define CRC16_KUNIT_TEST_SIZE 100

#define CRC16_KUNIT_SEED 0x12345678



/**

 * struct crc16_test - CRC16 test data

 * @crc: initial input value to CRC16

 * @start: Start index within the data buffer

 * @length: Length of the data

 */

static struct crc16_test {

	u16 crc;

	u16 start;

	u16 length;

} tests[CRC16_KUNIT_TEST_SIZE];



u8 data[CRC16_KUNIT_DATA_SIZE];





/* Naive implementation of CRC16 for validation purposes */

static inline u16 _crc16_naive_byte(u16 crc, u8 data)

{

	u8 i = 0;



	crc ^= (u16) data;

	for (i = 0; i < 8; i++) {

		if (crc & 0x01)

			crc = (crc >> 1) ^ 0xa001;

		else

			crc = crc >> 1;

	}



	return crc;

}





static inline u16 _crc16_naive(u16 crc, u8 *buffer, size_t len)

{

	while (len--)

		crc = _crc16_naive_byte(crc, *buffer++);

	return crc;

}





/* Small helper for generating pseudorandom 16-bit data */

static inline u16 _rand16(void)

{

	static u32 rand = CRC16_KUNIT_SEED;



	rand = next_pseudo_random32(rand);

	return rand & 0xFFFF;

}





static int crc16_init_test_data(struct kunit_suite *suite)

{

	size_t i;



	/* Fill the data buffer with random bytes */

	for (i = 0; i < CRC16_KUNIT_DATA_SIZE; i++)

		data[i] = _rand16() & 0xFF;



	/* Generate random test data while ensuring the random

	 * start + length values won't overflow the 4096-byte

	 * buffer (0x7FF * 2 = 0xFFE < 0x1000)

	 */

	for (size_t i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {

		tests[i].crc = _rand16();

		tests[i].start = _rand16() & 0x7FF;

		tests[i].length = _rand16() & 0x7FF;

	}



	return 0;

}



static void crc16_test_empty(struct kunit *test)

{

	u16 crc;



	/* The result for empty data should be the same as the

	 * initial crc

	 */

	crc = crc16(0x00, data, 0);

	KUNIT_EXPECT_EQ(test, crc, 0);

	crc = crc16(0xFF, data, 0);

	KUNIT_EXPECT_EQ(test, crc, 0xFF);

}



static void crc16_test_correctness(struct kunit *test)

{

	size_t i;

	u16 crc, crc_naive;



	for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {

		/* Compare results with the naive crc16 implementation */

		crc = crc16(tests[i].crc, data + tests[i].start,

			    tests[i].length);

		crc_naive = _crc16_naive(tests[i].crc, data + tests[i].start,

					 tests[i].length);

		KUNIT_EXPECT_EQ(test, crc, crc_naive);

	}

}





static void crc16_test_combine(struct kunit *test)

{

	size_t i, j;

	u16 crc, crc_naive;



	/* Make sure that combining two consecutive crc16 calculations

	 * yields the same result as calculating the crc16 for the whole thing

	 */

	for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {

		crc_naive = crc16(tests[i].crc, data + tests[i].start, tests[i].length);

		for (j = 0; j < tests[i].length; j++) {

			crc = crc16(tests[i].crc, data + tests[i].start, j);

			crc = crc16(crc, data + tests[i].start + j, tests[i].length - j);

			KUNIT_EXPECT_EQ(test, crc, crc_naive);

		}

	}

}





static struct kunit_case crc16_test_cases[] = {

	KUNIT_CASE(crc16_test_empty),

	KUNIT_CASE(crc16_test_combine),

	KUNIT_CASE(crc16_test_correctness),

	{},

};



static struct kunit_suite crc16_test_suite = {

	.name = "crc16",

	.test_cases = crc16_test_cases,

	.suite_init = crc16_init_test_data,

};

kunit_test_suite(crc16_test_suite);



MODULE_AUTHOR("Fabricio Gasperin <fgasperin@lkcamp.dev>");

MODULE_AUTHOR("Vinicius Peixoto <vpeixoto@lkcamp.dev>");

MODULE_AUTHOR("Enzo Bertoloti <ebertoloti@lkcamp.dev>");

MODULE_DESCRIPTION("Unit tests for crc16");

MODULE_LICENSE("GPL");