Commit af53e85e authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Andrew Morton
Browse files

xor: add a kunit test case 

Add a test case for the XOR routines loosely based on the CRC kunit
test.

Link: https://lkml.kernel.org/r/20260327061704.3707577-29-hch@lst.de


Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarEric Biggers <ebiggers@kernel.org>
Tested-by: default avatarEric Biggers <ebiggers@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: David Sterba <dsterba@suse.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Li Nan <linan122@huawei.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Song Liu <song@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a21921dd

lib/raid/.kunitconfig

0 → 100644
+3 −0
Original line number Diff line number Diff line 
CONFIG_KUNIT=y

CONFIG_BTRFS_FS=y

CONFIG_XOR_KUNIT_TEST=y

lib/raid/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -17,3 +17,14 @@ config XOR_BLOCKS_ARCH 
	default y if X86_32

	default y if X86_64

	bool



config XOR_KUNIT_TEST

	tristate "KUnit tests for xor_gen" if !KUNIT_ALL_TESTS

	depends on KUNIT

	depends on XOR_BLOCKS

	default KUNIT_ALL_TESTS

	help

	  Unit tests for the XOR library functions.



	  This is intended to help people writing architecture-specific

	  optimized versions.  If unsure, say N.

lib/raid/xor/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ xor-$(CONFIG_SPARC64) += sparc/xor-sparc64.o sparc/xor-sparc64-glue.o 
xor-$(CONFIG_S390)		+= s390/xor.o

xor-$(CONFIG_X86_32)		+= x86/xor-avx.o x86/xor-sse.o x86/xor-mmx.o

xor-$(CONFIG_X86_64)		+= x86/xor-avx.o x86/xor-sse.o



obj-y				+= tests/



CFLAGS_arm/xor-neon.o		+= $(CC_FLAGS_FPU)

CFLAGS_REMOVE_arm/xor-neon.o	+= $(CC_FLAGS_NO_FPU)

lib/raid/xor/tests/Makefile

0 → 100644
+3 −0
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only



obj-$(CONFIG_XOR_KUNIT_TEST) += xor_kunit.o

lib/raid/xor/tests/xor_kunit.c

0 → 100644
+187 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * Unit test the XOR library functions.

 *

 * Copyright 2024 Google LLC

 * Copyright 2026 Christoph Hellwig

 *

 * Based on the CRC tests by Eric Biggers <ebiggers@google.com>.

 */

#include <kunit/test.h>

#include <linux/prandom.h>

#include <linux/string_choices.h>

#include <linux/vmalloc.h>

#include <linux/raid/xor.h>



#define XOR_KUNIT_SEED			42

#define XOR_KUNIT_MAX_BYTES		16384

#define XOR_KUNIT_MAX_BUFFERS		64

#define XOR_KUNIT_NUM_TEST_ITERS	1000



static struct rnd_state rng;

static void *test_buffers[XOR_KUNIT_MAX_BUFFERS];

static void *test_dest;

static void *test_ref;

static size_t test_buflen;



static u32 rand32(void)

{

	return prandom_u32_state(&rng);

}



/* Reference implementation using dumb byte-wise XOR */

static void xor_ref(void *dest, void **srcs, unsigned int src_cnt,

		unsigned int bytes)

{

	unsigned int off, idx;

	u8 *d = dest;



	for (off = 0; off < bytes; off++) {

		for (idx = 0; idx < src_cnt; idx++) {

			u8 *src = srcs[idx];



			d[off] ^= src[off];

		}

	}

}



/* Generate a random length that is a multiple of 512. */

static unsigned int random_length(unsigned int max_length)

{

	return round_up((rand32() % max_length) + 1, 512);

}



/* Generate a random alignment that is a multiple of 64. */

static unsigned int random_alignment(unsigned int max_alignment)

{

	return ((rand32() % max_alignment) + 1) & ~63;

}



static void xor_generate_random_data(void)

{

	int i;



	prandom_bytes_state(&rng, test_dest, test_buflen);

	memcpy(test_ref, test_dest, test_buflen);

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

		prandom_bytes_state(&rng, test_buffers[i], test_buflen);

}



/* Test that xor_gen gives the same result as a reference implementation. */

static void xor_test(struct kunit *test)

{

	void *aligned_buffers[XOR_KUNIT_MAX_BUFFERS];

	size_t i;



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

		unsigned int nr_buffers =

			(rand32() % XOR_KUNIT_MAX_BUFFERS) + 1;

		unsigned int len = random_length(XOR_KUNIT_MAX_BYTES);

		unsigned int max_alignment, align = 0;

		void *buffers;



		if (rand32() % 8 == 0)

			/* Refresh the data occasionally. */

			xor_generate_random_data();



		/*

		 * If we're not using the entire buffer size, inject randomize

		 * alignment into the buffer.

		 */

		max_alignment = XOR_KUNIT_MAX_BYTES - len;

		if (max_alignment == 0) {

			buffers = test_buffers;

		} else if (rand32() % 2 == 0) {

			/* Use random alignments mod 64 */

			int j;



			for (j = 0; j < nr_buffers; j++)

				aligned_buffers[j] = test_buffers[j] +

					random_alignment(max_alignment);

			buffers = aligned_buffers;

			align = random_alignment(max_alignment);

		} else {

			/* Go up to the guard page, to catch buffer overreads */

			int j;



			align = test_buflen - len;

			for (j = 0; j < nr_buffers; j++)

				aligned_buffers[j] = test_buffers[j] + align;

			buffers = aligned_buffers;

		}



		/*

		 * Compute the XOR, and verify that it equals the XOR computed

		 * by a simple byte-at-a-time reference implementation.

		 */

		xor_ref(test_ref + align, buffers, nr_buffers, len);

		xor_gen(test_dest + align, buffers, nr_buffers, len);

		KUNIT_EXPECT_MEMEQ_MSG(test, test_ref + align,

				test_dest + align, len,

				"Wrong result with buffers=%u, len=%u, unaligned=%s, at_end=%s",

				nr_buffers, len,

				str_yes_no(max_alignment),

				str_yes_no(align + len == test_buflen));

	}

}



static struct kunit_case xor_test_cases[] = {

	KUNIT_CASE(xor_test),

	{},

};



static int xor_suite_init(struct kunit_suite *suite)

{

	int i;



	/*

	 * Allocate the test buffer using vmalloc() with a page-aligned length

	 * so that it is immediately followed by a guard page.  This allows

	 * buffer overreads to be detected, even in assembly code.

	 */

	test_buflen = round_up(XOR_KUNIT_MAX_BYTES, PAGE_SIZE);

	test_ref = vmalloc(test_buflen);

	if (!test_ref)

		return -ENOMEM;

	test_dest = vmalloc(test_buflen);

	if (!test_dest)

		goto out_free_ref;

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

		test_buffers[i] = vmalloc(test_buflen);

		if (!test_buffers[i])

			goto out_free_buffers;

	}



	prandom_seed_state(&rng, XOR_KUNIT_SEED);

	xor_generate_random_data();

	return 0;



out_free_buffers:

	while (--i >= 0)

		vfree(test_buffers[i]);

	vfree(test_dest);

out_free_ref:

	vfree(test_ref);

	return -ENOMEM;

}



static void xor_suite_exit(struct kunit_suite *suite)

{

	int i;



	vfree(test_ref);

	vfree(test_dest);

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

		vfree(test_buffers[i]);

}



static struct kunit_suite xor_test_suite = {

	.name		= "xor",

	.test_cases	= xor_test_cases,

	.suite_init	= xor_suite_init,

	.suite_exit	= xor_suite_exit,

};

kunit_test_suite(xor_test_suite);



MODULE_DESCRIPTION("Unit test for the XOR library functions");

MODULE_LICENSE("GPL");