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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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Tested-by: Eric 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: Andrew Morton <akpm@linux-foundation.org>

authored by

Christoph Hellwig and committed by
Andrew Morton af53e85e a21921dd

+205 -1
+3
lib/raid/.kunitconfig
··· 1 + CONFIG_KUNIT=y 2 + CONFIG_BTRFS_FS=y 3 + CONFIG_XOR_KUNIT_TEST=y
+11
lib/raid/Kconfig
··· 17 17 default y if X86_32 18 18 default y if X86_64 19 19 bool 20 + 21 + config XOR_KUNIT_TEST 22 + tristate "KUnit tests for xor_gen" if !KUNIT_ALL_TESTS 23 + depends on KUNIT 24 + depends on XOR_BLOCKS 25 + default KUNIT_ALL_TESTS 26 + help 27 + Unit tests for the XOR library functions. 28 + 29 + This is intended to help people writing architecture-specific 30 + optimized versions. If unsure, say N.
+1 -1
lib/raid/xor/Makefile
··· 29 29 xor-$(CONFIG_S390) += s390/xor.o 30 30 xor-$(CONFIG_X86_32) += x86/xor-avx.o x86/xor-sse.o x86/xor-mmx.o 31 31 xor-$(CONFIG_X86_64) += x86/xor-avx.o x86/xor-sse.o 32 - 32 + obj-y += tests/ 33 33 34 34 CFLAGS_arm/xor-neon.o += $(CC_FLAGS_FPU) 35 35 CFLAGS_REMOVE_arm/xor-neon.o += $(CC_FLAGS_NO_FPU)
+3
lib/raid/xor/tests/Makefile
··· 1 + # SPDX-License-Identifier: GPL-2.0-only 2 + 3 + obj-$(CONFIG_XOR_KUNIT_TEST) += xor_kunit.o
+187
lib/raid/xor/tests/xor_kunit.c
··· 1 + // SPDX-License-Identifier: GPL-2.0-or-later 2 + /* 3 + * Unit test the XOR library functions. 4 + * 5 + * Copyright 2024 Google LLC 6 + * Copyright 2026 Christoph Hellwig 7 + * 8 + * Based on the CRC tests by Eric Biggers <ebiggers@google.com>. 9 + */ 10 + #include <kunit/test.h> 11 + #include <linux/prandom.h> 12 + #include <linux/string_choices.h> 13 + #include <linux/vmalloc.h> 14 + #include <linux/raid/xor.h> 15 + 16 + #define XOR_KUNIT_SEED 42 17 + #define XOR_KUNIT_MAX_BYTES 16384 18 + #define XOR_KUNIT_MAX_BUFFERS 64 19 + #define XOR_KUNIT_NUM_TEST_ITERS 1000 20 + 21 + static struct rnd_state rng; 22 + static void *test_buffers[XOR_KUNIT_MAX_BUFFERS]; 23 + static void *test_dest; 24 + static void *test_ref; 25 + static size_t test_buflen; 26 + 27 + static u32 rand32(void) 28 + { 29 + return prandom_u32_state(&rng); 30 + } 31 + 32 + /* Reference implementation using dumb byte-wise XOR */ 33 + static void xor_ref(void *dest, void **srcs, unsigned int src_cnt, 34 + unsigned int bytes) 35 + { 36 + unsigned int off, idx; 37 + u8 *d = dest; 38 + 39 + for (off = 0; off < bytes; off++) { 40 + for (idx = 0; idx < src_cnt; idx++) { 41 + u8 *src = srcs[idx]; 42 + 43 + d[off] ^= src[off]; 44 + } 45 + } 46 + } 47 + 48 + /* Generate a random length that is a multiple of 512. */ 49 + static unsigned int random_length(unsigned int max_length) 50 + { 51 + return round_up((rand32() % max_length) + 1, 512); 52 + } 53 + 54 + /* Generate a random alignment that is a multiple of 64. */ 55 + static unsigned int random_alignment(unsigned int max_alignment) 56 + { 57 + return ((rand32() % max_alignment) + 1) & ~63; 58 + } 59 + 60 + static void xor_generate_random_data(void) 61 + { 62 + int i; 63 + 64 + prandom_bytes_state(&rng, test_dest, test_buflen); 65 + memcpy(test_ref, test_dest, test_buflen); 66 + for (i = 0; i < XOR_KUNIT_MAX_BUFFERS; i++) 67 + prandom_bytes_state(&rng, test_buffers[i], test_buflen); 68 + } 69 + 70 + /* Test that xor_gen gives the same result as a reference implementation. */ 71 + static void xor_test(struct kunit *test) 72 + { 73 + void *aligned_buffers[XOR_KUNIT_MAX_BUFFERS]; 74 + size_t i; 75 + 76 + for (i = 0; i < XOR_KUNIT_NUM_TEST_ITERS; i++) { 77 + unsigned int nr_buffers = 78 + (rand32() % XOR_KUNIT_MAX_BUFFERS) + 1; 79 + unsigned int len = random_length(XOR_KUNIT_MAX_BYTES); 80 + unsigned int max_alignment, align = 0; 81 + void *buffers; 82 + 83 + if (rand32() % 8 == 0) 84 + /* Refresh the data occasionally. */ 85 + xor_generate_random_data(); 86 + 87 + /* 88 + * If we're not using the entire buffer size, inject randomize 89 + * alignment into the buffer. 90 + */ 91 + max_alignment = XOR_KUNIT_MAX_BYTES - len; 92 + if (max_alignment == 0) { 93 + buffers = test_buffers; 94 + } else if (rand32() % 2 == 0) { 95 + /* Use random alignments mod 64 */ 96 + int j; 97 + 98 + for (j = 0; j < nr_buffers; j++) 99 + aligned_buffers[j] = test_buffers[j] + 100 + random_alignment(max_alignment); 101 + buffers = aligned_buffers; 102 + align = random_alignment(max_alignment); 103 + } else { 104 + /* Go up to the guard page, to catch buffer overreads */ 105 + int j; 106 + 107 + align = test_buflen - len; 108 + for (j = 0; j < nr_buffers; j++) 109 + aligned_buffers[j] = test_buffers[j] + align; 110 + buffers = aligned_buffers; 111 + } 112 + 113 + /* 114 + * Compute the XOR, and verify that it equals the XOR computed 115 + * by a simple byte-at-a-time reference implementation. 116 + */ 117 + xor_ref(test_ref + align, buffers, nr_buffers, len); 118 + xor_gen(test_dest + align, buffers, nr_buffers, len); 119 + KUNIT_EXPECT_MEMEQ_MSG(test, test_ref + align, 120 + test_dest + align, len, 121 + "Wrong result with buffers=%u, len=%u, unaligned=%s, at_end=%s", 122 + nr_buffers, len, 123 + str_yes_no(max_alignment), 124 + str_yes_no(align + len == test_buflen)); 125 + } 126 + } 127 + 128 + static struct kunit_case xor_test_cases[] = { 129 + KUNIT_CASE(xor_test), 130 + {}, 131 + }; 132 + 133 + static int xor_suite_init(struct kunit_suite *suite) 134 + { 135 + int i; 136 + 137 + /* 138 + * Allocate the test buffer using vmalloc() with a page-aligned length 139 + * so that it is immediately followed by a guard page. This allows 140 + * buffer overreads to be detected, even in assembly code. 141 + */ 142 + test_buflen = round_up(XOR_KUNIT_MAX_BYTES, PAGE_SIZE); 143 + test_ref = vmalloc(test_buflen); 144 + if (!test_ref) 145 + return -ENOMEM; 146 + test_dest = vmalloc(test_buflen); 147 + if (!test_dest) 148 + goto out_free_ref; 149 + for (i = 0; i < XOR_KUNIT_MAX_BUFFERS; i++) { 150 + test_buffers[i] = vmalloc(test_buflen); 151 + if (!test_buffers[i]) 152 + goto out_free_buffers; 153 + } 154 + 155 + prandom_seed_state(&rng, XOR_KUNIT_SEED); 156 + xor_generate_random_data(); 157 + return 0; 158 + 159 + out_free_buffers: 160 + while (--i >= 0) 161 + vfree(test_buffers[i]); 162 + vfree(test_dest); 163 + out_free_ref: 164 + vfree(test_ref); 165 + return -ENOMEM; 166 + } 167 + 168 + static void xor_suite_exit(struct kunit_suite *suite) 169 + { 170 + int i; 171 + 172 + vfree(test_ref); 173 + vfree(test_dest); 174 + for (i = 0; i < XOR_KUNIT_MAX_BUFFERS; i++) 175 + vfree(test_buffers[i]); 176 + } 177 + 178 + static struct kunit_suite xor_test_suite = { 179 + .name = "xor", 180 + .test_cases = xor_test_cases, 181 + .suite_init = xor_suite_init, 182 + .suite_exit = xor_suite_exit, 183 + }; 184 + kunit_test_suite(xor_test_suite); 185 + 186 + MODULE_DESCRIPTION("Unit test for the XOR library functions"); 187 + MODULE_LICENSE("GPL");