[linux.git] / lib / test_hash.c

/*
 * Test cases for <linux/hash.h> and <linux/stringhash.h>
 * This just verifies that various ways of computing a hash
 * produce the same thing and, for cases where a k-bit hash
 * value is requested, is of the requested size.
 *
 * We fill a buffer with a 255-byte null-terminated string,
 * and use both full_name_hash() and hashlen_string() to hash the
 * substrings from i to j, where 0 <= i < j < 256.
 *
 * The returned values are used to check that __hash_32() and
 * __hash_32_generic() compute the same thing.  Likewise hash_32()
 * and hash_64().
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n"

#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/hash.h>
#include <linux/stringhash.h>
#include <linux/printk.h>

/* 32-bit XORSHIFT generator.  Seed must not be zero. */
static u32 __init __attribute_const__
xorshift(u32 seed)
{
	seed ^= seed << 13;
	seed ^= seed >> 17;
	seed ^= seed << 5;
	return seed;
}

/* Given a non-zero x, returns a non-zero byte. */
static u8 __init __attribute_const__
mod255(u32 x)
{
	x = (x & 0xffff) + (x >> 16);	/* 1 <= x <= 0x1fffe */
	x = (x & 0xff) + (x >> 8);	/* 1 <= x <= 0x2fd */
	x = (x & 0xff) + (x >> 8);	/* 1 <= x <= 0x100 */
	x = (x & 0xff) + (x >> 8);	/* 1 <= x <= 0xff */
	return x;
}

/* Fill the buffer with non-zero bytes. */
static void __init
fill_buf(char *buf, size_t len, u32 seed)
{
	size_t i;

	for (i = 0; i < len; i++) {
		seed = xorshift(seed);
		buf[i] = mod255(seed);
	}
}

/*
 * Test the various integer hash functions.  h64 (or its low-order bits)
 * is the integer to hash.  hash_or accumulates the OR of the hash values,
 * which are later checked to see that they cover all the requested bits.
 *
 * Because these functions (as opposed to the string hashes) are all
 * inline, the code being tested is actually in the module, and you can
 * recompile and re-test the module without rebooting.
 */
static bool __init
test_int_hash(unsigned long long h64, u32 hash_or[2][33])
{
	int k;
	u32 h0 = (u32)h64, h1, h2;

	/* Test __hash32 */
	hash_or[0][0] |= h1 = __hash_32(h0);
#ifdef HAVE_ARCH__HASH_32
	hash_or[1][0] |= h2 = __hash_32_generic(h0);
#if HAVE_ARCH__HASH_32 == 1
	if (h1 != h2) {
		pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
			h0, h1, h2);
		return false;
	}
#endif
#endif

	/* Test k = 1..32 bits */
	for (k = 1; k <= 32; k++) {
		u32 const m = ((u32)2 << (k-1)) - 1;	/* Low k bits set */

		/* Test hash_32 */
		hash_or[0][k] |= h1 = hash_32(h0, k);
		if (h1 > m) {
			pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m);
			return false;
		}
#ifdef HAVE_ARCH_HASH_32
		h2 = hash_32_generic(h0, k);
#if HAVE_ARCH_HASH_32 == 1
		if (h1 != h2) {
			pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() "
				" = %#x", h0, k, h1, h2);
			return false;
		}
#else
		if (h2 > m) {
			pr_err("hash_32_generic(%#x, %d) = %#x > %#x",
				h0, k, h1, m);
			return false;
		}
#endif
#endif
		/* Test hash_64 */
		hash_or[1][k] |= h1 = hash_64(h64, k);
		if (h1 > m) {
			pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m);
			return false;
		}
#ifdef HAVE_ARCH_HASH_64
		h2 = hash_64_generic(h64, k);
#if HAVE_ARCH_HASH_64 == 1
		if (h1 != h2) {
			pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() "
				"= %#x", h64, k, h1, h2);
			return false;
		}
#else
		if (h2 > m) {
			pr_err("hash_64_generic(%#llx, %d) = %#x > %#x",
				h64, k, h1, m);
			return false;
		}
#endif
#endif
	}

	(void)h2;	/* Suppress unused variable warning */
	return true;
}

#define SIZE 256	/* Run time is cubic in SIZE */

static int __init
test_hash_init(void)
{
	char buf[SIZE+1];
	u32 string_or = 0, hash_or[2][33] = { { 0, } };
	unsigned tests = 0;
	unsigned long long h64 = 0;
	int i, j;

	fill_buf(buf, SIZE, 1);

	/* Test every possible non-empty substring in the buffer. */
	for (j = SIZE; j > 0; --j) {
		buf[j] = '\0';

		for (i = 0; i <= j; i++) {
			u64 hashlen = hashlen_string(buf+i, buf+i);
			u32 h0 = full_name_hash(buf+i, buf+i, j-i);

			/* Check that hashlen_string gets the length right */
			if (hashlen_len(hashlen) != j-i) {
				pr_err("hashlen_string(%d..%d) returned length"
					" %u, expected %d",
					i, j, hashlen_len(hashlen), j-i);
				return -EINVAL;
			}
			/* Check that the hashes match */
			if (hashlen_hash(hashlen) != h0) {
				pr_err("hashlen_string(%d..%d) = %08x != "
					"full_name_hash() = %08x",
					i, j, hashlen_hash(hashlen), h0);
				return -EINVAL;
			}

			string_or |= h0;
			h64 = h64 << 32 | h0;	/* For use with hash_64 */
			if (!test_int_hash(h64, hash_or))
				return -EINVAL;
			tests++;
		} /* i */
	} /* j */

	/* The OR of all the hash values should cover all the bits */
	if (~string_or) {
		pr_err("OR of all string hash results = %#x != %#x",
			string_or, -1u);
		return -EINVAL;
	}
	if (~hash_or[0][0]) {
		pr_err("OR of all __hash_32 results = %#x != %#x",
			hash_or[0][0], -1u);
		return -EINVAL;
	}
#ifdef HAVE_ARCH__HASH_32
#if HAVE_ARCH__HASH_32 != 1	/* Test is pointless if results match */
	if (~hash_or[1][0]) {
		pr_err("OR of all __hash_32_generic results = %#x != %#x",
			hash_or[1][0], -1u);
		return -EINVAL;
	}
#endif
#endif

	/* Likewise for all the i-bit hash values */
	for (i = 1; i <= 32; i++) {
		u32 const m = ((u32)2 << (i-1)) - 1;	/* Low i bits set */

		if (hash_or[0][i] != m) {
			pr_err("OR of all hash_32(%d) results = %#x "
				"(%#x expected)", i, hash_or[0][i], m);
			return -EINVAL;
		}
		if (hash_or[1][i] != m) {
			pr_err("OR of all hash_64(%d) results = %#x "
				"(%#x expected)", i, hash_or[1][i], m);
			return -EINVAL;
		}
	}

	/* Issue notices about skipped tests. */
#ifdef HAVE_ARCH__HASH_32
#if HAVE_ARCH__HASH_32 != 1
	pr_info("__hash_32() is arch-specific; not compared to generic.");
#endif
#else
	pr_info("__hash_32() has no arch implementation to test.");
#endif
#ifdef HAVE_ARCH_HASH_32
#if HAVE_ARCH_HASH_32 != 1
	pr_info("hash_32() is arch-specific; not compared to generic.");
#endif
#else
	pr_info("hash_32() has no arch implementation to test.");
#endif
#ifdef HAVE_ARCH_HASH_64
#if HAVE_ARCH_HASH_64 != 1
	pr_info("hash_64() is arch-specific; not compared to generic.");
#endif
#else
	pr_info("hash_64() has no arch implementation to test.");
#endif

	pr_notice("%u tests passed.", tests);

	return 0;
}

static void __exit test_hash_exit(void)
{
}

module_init(test_hash_init);	/* Does everything */
module_exit(test_hash_exit);	/* Does nothing */

MODULE_LICENSE("GPL");
Commit	Line	Data
468a9428 GS	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. */
	26	static u32 __init __attribute_const__
	27	xorshift(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. */
	36	static u8 __init __attribute_const__
	37	mod255(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. */
	47	static void __init
	48	fill_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	*/
67	static bool __init
68	test_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
142	static int __init
143	test_hash_init(void)
144	{
145	char buf[SIZE+1];
ed76b7a1	146	u32 string_or = 0, hash_or[2][33] = { { 0, } };
468a9428 GS	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++) {
8387ff25 LT	158	u64 hashlen = hashlen_string(buf+i, buf+i);
8387ff25 LT	159	u32 h0 = full_name_hash(buf+i, buf+i, j-i);
468a9428 GS	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. */
e6173ba4 GU	222	#ifdef HAVE_ARCH__HASH_32
e6173ba4 GU	223	#if HAVE_ARCH__HASH_32 != 1
468a9428 GS	224	pr_info("__hash_32() is arch-specific; not compared to generic.");
468a9428 GS	225	#endif
e6173ba4 GU	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
468a9428 GS	231	pr_info("hash_32() is arch-specific; not compared to generic.");
468a9428 GS	232	#endif
e6173ba4 GU	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
468a9428 GS	238	pr_info("hash_64() is arch-specific; not compared to generic.");
468a9428 GS	239	#endif
e6173ba4 GU	240	#else
	241	pr_info("hash_64() has no arch implementation to test.");
	242	#endif
468a9428 GS	243
	244	pr_notice("%u tests passed.", tests);
	245
	246	return 0;
	247	}
	248
	249	static void __exit test_hash_exit(void)
	250	{
	251	}
	252
	253	module_init(test_hash_init); /* Does everything */
	254	module_exit(test_hash_exit); /* Does nothing */
	255
	256	MODULE_LICENSE("GPL");