1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Test cases for <linux/hash.h> and <linux/stringhash.h>
4 * This just verifies that various ways of computing a hash
5 * produce the same thing and, for cases where a k-bit hash
6 * 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 the
10 * substrings from i to j, where 0 <= i < j < 256.
11 *
12 * The returned values are used to check that __hash_32() and
13 * __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_32
71static void
72test_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 == 1
76	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#endif
80}
81#endif
82
83#ifdef HAVE_ARCH_HASH_64
84static void
85test_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 == 1
89	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#else
93	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#endif
97}
98#endif
99
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 all
106 * inline, the code being tested is actually in the module, and you can
107 * recompile and re-test the module without rebooting.
108 */
109static void
110test_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_32
118	test_int__hash_32(test, &params);
119#endif
120
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_64
137		test_int_hash_64(test, &params, &m, &k);
138#endif
139	}
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_32
204#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#endif
209#endif
210
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_LICENSE("GPL");
239