1/*
  2 * Test cases for <linux/hash.h> and <linux/stringhash.h>
  3 * This just verifies that various ways of computing a hash
  4 * produce the same thing and, for cases where a k-bit hash
  5 * value is requested, is of the requested size.
  6 *
  7 * We fill a buffer with a 255-byte null-terminated string,
  8 * and use both full_name_hash() and hashlen_string() to hash the
  9 * substrings from i to j, where 0 <= i < j < 256.
 10 *
 11 * The returned values are used to check that __hash_32() and
 12 * __hash_32_generic() compute the same thing.  Likewise hash_32()
 13 * and hash_64().
 14 */
 15
 16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n"
 17
 18#include <linux/compiler.h>
 19#include <linux/types.h>
 20#include <linux/module.h>
 21#include <linux/hash.h>
 22#include <linux/stringhash.h>
 23#include <linux/printk.h>
 24
 25/* 32-bit XORSHIFT generator.  Seed must not be zero. */
 26static u32 __init __attribute_const__
 27xorshift(u32 seed)
 28{
 29	seed ^= seed << 13;
 30	seed ^= seed >> 17;
 31	seed ^= seed << 5;
 32	return seed;
 33}
 34
 35/* Given a non-zero x, returns a non-zero byte. */
 36static u8 __init __attribute_const__
 37mod255(u32 x)
 38{
 39	x = (x & 0xffff) + (x >> 16);	/* 1 <= x <= 0x1fffe */
 40	x = (x & 0xff) + (x >> 8);	/* 1 <= x <= 0x2fd */
 41	x = (x & 0xff) + (x >> 8);	/* 1 <= x <= 0x100 */
 42	x = (x & 0xff) + (x >> 8);	/* 1 <= x <= 0xff */
 43	return x;
 44}
 45
 46/* Fill the buffer with non-zero bytes. */
 47static void __init
 48fill_buf(char *buf, size_t len, u32 seed)
 49{
 50	size_t i;
 51
 52	for (i = 0; i < len; i++) {
 53		seed = xorshift(seed);
 54		buf[i] = mod255(seed);
 55	}
 56}
 57
 58/*
 59 * Test the various integer hash functions.  h64 (or its low-order bits)
 60 * is the integer to hash.  hash_or accumulates the OR of the hash values,
 61 * which are later checked to see that they cover all the requested bits.
 62 *
 63 * Because these functions (as opposed to the string hashes) are all
 64 * inline, the code being tested is actually in the module, and you can
 65 * recompile and re-test the module without rebooting.
 66 */
 67static bool __init
 68test_int_hash(unsigned long long h64, u32 hash_or[2][33])
 69{
 70	int k;
 71	u32 h0 = (u32)h64, h1, h2;
 72
 73	/* Test __hash32 */
 74	hash_or[0][0] |= h1 = __hash_32(h0);
 75#ifdef HAVE_ARCH__HASH_32
 76	hash_or[1][0] |= h2 = __hash_32_generic(h0);
 77#if HAVE_ARCH__HASH_32 == 1
 78	if (h1 != h2) {
 79		pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
 80			h0, h1, h2);
 81		return false;
 82	}
 83#endif
 84#endif
 85
 86	/* Test k = 1..32 bits */
 87	for (k = 1; k <= 32; k++) {
 88		u32 const m = ((u32)2 << (k-1)) - 1;	/* Low k bits set */
 89
 90		/* Test hash_32 */
 91		hash_or[0][k] |= h1 = hash_32(h0, k);
 92		if (h1 > m) {
 93			pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m);
 94			return false;
 95		}
 96#ifdef HAVE_ARCH_HASH_32
 97		h2 = hash_32_generic(h0, k);
 98#if HAVE_ARCH_HASH_32 == 1
 99		if (h1 != h2) {
100			pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() "
101				" = %#x", h0, k, h1, h2);
102			return false;
103		}
104#else
105		if (h2 > m) {
106			pr_err("hash_32_generic(%#x, %d) = %#x > %#x",
107				h0, k, h1, m);
108			return false;
109		}
110#endif
111#endif
112		/* Test hash_64 */
113		hash_or[1][k] |= h1 = hash_64(h64, k);
114		if (h1 > m) {
115			pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m);
116			return false;
117		}
118#ifdef HAVE_ARCH_HASH_64
119		h2 = hash_64_generic(h64, k);
120#if HAVE_ARCH_HASH_64 == 1
121		if (h1 != h2) {
122			pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() "
123				"= %#x", h64, k, h1, h2);
124			return false;
125		}
126#else
127		if (h2 > m) {
128			pr_err("hash_64_generic(%#llx, %d) = %#x > %#x",
129				h64, k, h1, m);
130			return false;
131		}
132#endif
133#endif
134	}
135
136	(void)h2;	/* Suppress unused variable warning */
137	return true;
138}
139
140#define SIZE 256	/* Run time is cubic in SIZE */
141
142static int __init
143test_hash_init(void)
144{
145	char buf[SIZE+1];
146	u32 string_or = 0, hash_or[2][33] = { { 0, } };
147	unsigned tests = 0;
148	unsigned long long h64 = 0;
149	int i, j;
150
151	fill_buf(buf, SIZE, 1);
152
153	/* Test every possible non-empty substring in the buffer. */
154	for (j = SIZE; j > 0; --j) {
155		buf[j] = '\0';
156
157		for (i = 0; i <= j; i++) {
158			u64 hashlen = hashlen_string(buf+i, buf+i);
159			u32 h0 = full_name_hash(buf+i, buf+i, j-i);
160
161			/* Check that hashlen_string gets the length right */
162			if (hashlen_len(hashlen) != j-i) {
163				pr_err("hashlen_string(%d..%d) returned length"
164					" %u, expected %d",
165					i, j, hashlen_len(hashlen), j-i);
166				return -EINVAL;
167			}
168			/* Check that the hashes match */
169			if (hashlen_hash(hashlen) != h0) {
170				pr_err("hashlen_string(%d..%d) = %08x != "
171					"full_name_hash() = %08x",
172					i, j, hashlen_hash(hashlen), h0);
173				return -EINVAL;
174			}
175
176			string_or |= h0;
177			h64 = h64 << 32 | h0;	/* For use with hash_64 */
178			if (!test_int_hash(h64, hash_or))
179				return -EINVAL;
180			tests++;
181		} /* i */
182	} /* j */
183
184	/* The OR of all the hash values should cover all the bits */
185	if (~string_or) {
186		pr_err("OR of all string hash results = %#x != %#x",
187			string_or, -1u);
188		return -EINVAL;
189	}
190	if (~hash_or[0][0]) {
191		pr_err("OR of all __hash_32 results = %#x != %#x",
192			hash_or[0][0], -1u);
193		return -EINVAL;
194	}
195#ifdef HAVE_ARCH__HASH_32
196#if HAVE_ARCH__HASH_32 != 1	/* Test is pointless if results match */
197	if (~hash_or[1][0]) {
198		pr_err("OR of all __hash_32_generic results = %#x != %#x",
199			hash_or[1][0], -1u);
200		return -EINVAL;
201	}
202#endif
203#endif
204
205	/* Likewise for all the i-bit hash values */
206	for (i = 1; i <= 32; i++) {
207		u32 const m = ((u32)2 << (i-1)) - 1;	/* Low i bits set */
208
209		if (hash_or[0][i] != m) {
210			pr_err("OR of all hash_32(%d) results = %#x "
211				"(%#x expected)", i, hash_or[0][i], m);
212			return -EINVAL;
213		}
214		if (hash_or[1][i] != m) {
215			pr_err("OR of all hash_64(%d) results = %#x "
216				"(%#x expected)", i, hash_or[1][i], m);
217			return -EINVAL;
218		}
219	}
220
221	/* Issue notices about skipped tests. */
222#ifdef HAVE_ARCH__HASH_32
223#if HAVE_ARCH__HASH_32 != 1
224	pr_info("__hash_32() is arch-specific; not compared to generic.");
225#endif
226#else
227	pr_info("__hash_32() has no arch implementation to test.");
228#endif
229#ifdef HAVE_ARCH_HASH_32
230#if HAVE_ARCH_HASH_32 != 1
231	pr_info("hash_32() is arch-specific; not compared to generic.");
232#endif
233#else
234	pr_info("hash_32() has no arch implementation to test.");
235#endif
236#ifdef HAVE_ARCH_HASH_64
237#if HAVE_ARCH_HASH_64 != 1
238	pr_info("hash_64() is arch-specific; not compared to generic.");
239#endif
240#else
241	pr_info("hash_64() has no arch implementation to test.");
242#endif
243
244	pr_notice("%u tests passed.", tests);
245
246	return 0;
247}
248
249static void __exit test_hash_exit(void)
250{
251}
252
253module_init(test_hash_init);	/* Does everything */
254module_exit(test_hash_exit);	/* Does nothing */
255
256MODULE_LICENSE("GPL");