240 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Test cases for <linux/hash.h> and <linux/stringhash.h>4 * This just verifies that various ways of computing a hash5 * produce the same thing and, for cases where a k-bit hash6 * value is requested, is of the requested size.7 *8 * We fill a buffer with a 255-byte null-terminated string,9 * and use both full_name_hash() and hashlen_string() to hash the10 * substrings from i to j, where 0 <= i < j < 256.11 *12 * The returned values are used to check that __hash_32() and13 * __hash_32_generic() compute the same thing. Likewise hash_32()14 * and hash_64().15 */16 17#include <linux/compiler.h>18#include <linux/types.h>19#include <linux/module.h>20#include <linux/hash.h>21#include <linux/stringhash.h>22#include <kunit/test.h>23 24/* 32-bit XORSHIFT generator. Seed must not be zero. */25static u32 __attribute_const__26xorshift(u32 seed)27{28 seed ^= seed << 13;29 seed ^= seed >> 17;30 seed ^= seed << 5;31 return seed;32}33 34/* Given a non-zero x, returns a non-zero byte. */35static u8 __attribute_const__36mod255(u32 x)37{38 x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */39 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */40 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */41 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */42 return x;43}44 45/* Fill the buffer with non-zero bytes. */46static void fill_buf(char *buf, size_t len, u32 seed)47{48 size_t i;49 50 for (i = 0; i < len; i++) {51 seed = xorshift(seed);52 buf[i] = mod255(seed);53 }54}55 56/* Holds most testing variables for the int test. */57struct test_hash_params {58 /* Pointer to integer to be hashed. */59 unsigned long long *h64;60 /* Low 32-bits of integer to be hashed. */61 u32 h0;62 /* Arch-specific hash result. */63 u32 h1;64 /* Generic hash result. */65 u32 h2;66 /* ORed hashes of given size (in bits). */67 u32 (*hash_or)[33];68};69 70#ifdef HAVE_ARCH__HASH_3271static void72test_int__hash_32(struct kunit *test, struct test_hash_params *params)73{74 params->hash_or[1][0] |= params->h2 = __hash_32_generic(params->h0);75#if HAVE_ARCH__HASH_32 == 176 KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,77 "__hash_32(%#x) = %#x != __hash_32_generic() = %#x",78 params->h0, params->h1, params->h2);79#endif80}81#endif82 83#ifdef HAVE_ARCH_HASH_6484static void85test_int_hash_64(struct kunit *test, struct test_hash_params *params, u32 const *m, int *k)86{87 params->h2 = hash_64_generic(*params->h64, *k);88#if HAVE_ARCH_HASH_64 == 189 KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,90 "hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x",91 *params->h64, *k, params->h1, params->h2);92#else93 KUNIT_EXPECT_LE_MSG(test, params->h1, params->h2,94 "hash_64_generic(%#llx, %d) = %#x > %#x",95 *params->h64, *k, params->h1, *m);96#endif97}98#endif99 100/*101 * Test the various integer hash functions. h64 (or its low-order bits)102 * is the integer to hash. hash_or accumulates the OR of the hash values,103 * which are later checked to see that they cover all the requested bits.104 *105 * Because these functions (as opposed to the string hashes) are all106 * inline, the code being tested is actually in the module, and you can107 * recompile and re-test the module without rebooting.108 */109static void110test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33])111{112 int k;113 struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or };114 115 /* Test __hash32 */116 hash_or[0][0] |= params.h1 = __hash_32(params.h0);117#ifdef HAVE_ARCH__HASH_32118 test_int__hash_32(test, ¶ms);119#endif120 121 /* Test k = 1..32 bits */122 for (k = 1; k <= 32; k++) {123 u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */124 125 /* Test hash_32 */126 hash_or[0][k] |= params.h1 = hash_32(params.h0, k);127 KUNIT_EXPECT_LE_MSG(test, params.h1, m,128 "hash_32(%#x, %d) = %#x > %#x",129 params.h0, k, params.h1, m);130 131 /* Test hash_64 */132 hash_or[1][k] |= params.h1 = hash_64(h64, k);133 KUNIT_EXPECT_LE_MSG(test, params.h1, m,134 "hash_64(%#llx, %d) = %#x > %#x",135 h64, k, params.h1, m);136#ifdef HAVE_ARCH_HASH_64137 test_int_hash_64(test, ¶ms, &m, &k);138#endif139 }140}141 142#define SIZE 256 /* Run time is cubic in SIZE */143 144static void test_string_or(struct kunit *test)145{146 char buf[SIZE+1];147 u32 string_or = 0;148 int i, j;149 150 fill_buf(buf, SIZE, 1);151 152 /* Test every possible non-empty substring in the buffer. */153 for (j = SIZE; j > 0; --j) {154 buf[j] = '\0';155 156 for (i = 0; i <= j; i++) {157 u32 h0 = full_name_hash(buf+i, buf+i, j-i);158 159 string_or |= h0;160 } /* i */161 } /* j */162 163 /* The OR of all the hash values should cover all the bits */164 KUNIT_EXPECT_EQ_MSG(test, string_or, -1u,165 "OR of all string hash results = %#x != %#x",166 string_or, -1u);167}168 169static void test_hash_or(struct kunit *test)170{171 char buf[SIZE+1];172 u32 hash_or[2][33] = { { 0, } };173 unsigned long long h64 = 0;174 int i, j;175 176 fill_buf(buf, SIZE, 1);177 178 /* Test every possible non-empty substring in the buffer. */179 for (j = SIZE; j > 0; --j) {180 buf[j] = '\0';181 182 for (i = 0; i <= j; i++) {183 u64 hashlen = hashlen_string(buf+i, buf+i);184 u32 h0 = full_name_hash(buf+i, buf+i, j-i);185 186 /* Check that hashlen_string gets the length right */187 KUNIT_EXPECT_EQ_MSG(test, hashlen_len(hashlen), j-i,188 "hashlen_string(%d..%d) returned length %u, expected %d",189 i, j, hashlen_len(hashlen), j-i);190 /* Check that the hashes match */191 KUNIT_EXPECT_EQ_MSG(test, hashlen_hash(hashlen), h0,192 "hashlen_string(%d..%d) = %08x != full_name_hash() = %08x",193 i, j, hashlen_hash(hashlen), h0);194 195 h64 = h64 << 32 | h0; /* For use with hash_64 */196 test_int_hash(test, h64, hash_or);197 } /* i */198 } /* j */199 200 KUNIT_EXPECT_EQ_MSG(test, hash_or[0][0], -1u,201 "OR of all __hash_32 results = %#x != %#x",202 hash_or[0][0], -1u);203#ifdef HAVE_ARCH__HASH_32204#if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */205 KUNIT_EXPECT_EQ_MSG(test, hash_or[1][0], -1u,206 "OR of all __hash_32_generic results = %#x != %#x",207 hash_or[1][0], -1u);208#endif209#endif210 211 /* Likewise for all the i-bit hash values */212 for (i = 1; i <= 32; i++) {213 u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */214 215 KUNIT_EXPECT_EQ_MSG(test, hash_or[0][i], m,216 "OR of all hash_32(%d) results = %#x (%#x expected)",217 i, hash_or[0][i], m);218 KUNIT_EXPECT_EQ_MSG(test, hash_or[1][i], m,219 "OR of all hash_64(%d) results = %#x (%#x expected)",220 i, hash_or[1][i], m);221 }222}223 224static struct kunit_case hash_test_cases[] __refdata = {225 KUNIT_CASE(test_string_or),226 KUNIT_CASE(test_hash_or),227 {}228};229 230static struct kunit_suite hash_test_suite = {231 .name = "hash",232 .test_cases = hash_test_cases,233};234 235 236kunit_test_suite(hash_test_suite);237 238MODULE_DESCRIPTION("Test cases for <linux/hash.h> and <linux/stringhash.h>");239MODULE_LICENSE("GPL");240