[linux.git] / lib / test_hash.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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().
 */

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

/* 32-bit XORSHIFT generator.  Seed must not be zero. */
static u32 __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 __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 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);
	}
}

/* Holds most testing variables for the int test. */
struct test_hash_params {
        /* Pointer to integer to be hashed. */
	unsigned long long *h64;
        /* Low 32-bits of integer to be hashed. */
	u32 h0;
        /* Arch-specific hash result. */
	u32 h1;
        /* Generic hash result. */
	u32 h2;
        /* ORed hashes of given size (in bits). */
	u32 (*hash_or)[33];
};

#ifdef HAVE_ARCH__HASH_32
static void
test_int__hash_32(struct kunit *test, struct test_hash_params *params)
{
	params->hash_or[1][0] |= params->h2 = __hash_32_generic(params->h0);
#if HAVE_ARCH__HASH_32 == 1
	KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
			    "__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
			    params->h0, params->h1, params->h2);
#endif
}
#endif

#ifdef HAVE_ARCH_HASH_64
static void
test_int_hash_64(struct kunit *test, struct test_hash_params *params, u32 const *m, int *k)
{
	params->h2 = hash_64_generic(*params->h64, *k);
#if HAVE_ARCH_HASH_64 == 1
	KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
			    "hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x",
			    *params->h64, *k, params->h1, params->h2);
#else
	KUNIT_EXPECT_LE_MSG(test, params->h1, params->h2,
			    "hash_64_generic(%#llx, %d) = %#x > %#x",
			    *params->h64, *k, params->h1, *m);
#endif
}
#endif

/*
 * 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 void
test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33])
{
	int k;
	struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or };

	/* Test __hash32 */
	hash_or[0][0] |= params.h1 = __hash_32(params.h0);
#ifdef HAVE_ARCH__HASH_32
	test_int__hash_32(test, &params);
#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] |= params.h1 = hash_32(params.h0, k);
		KUNIT_EXPECT_LE_MSG(test, params.h1, m,
				    "hash_32(%#x, %d) = %#x > %#x",
				    params.h0, k, params.h1, m);

		/* Test hash_64 */
		hash_or[1][k] |= params.h1 = hash_64(h64, k);
		KUNIT_EXPECT_LE_MSG(test, params.h1, m,
				    "hash_64(%#llx, %d) = %#x > %#x",
				    h64, k, params.h1, m);
#ifdef HAVE_ARCH_HASH_64
		test_int_hash_64(test, &params, &m, &k);
#endif
	}
}

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

static void test_string_or(struct kunit *test)
{
	char buf[SIZE+1];
	u32 string_or = 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++) {
			u32 h0 = full_name_hash(buf+i, buf+i, j-i);

			string_or |= h0;
		} /* i */
	} /* j */

	/* The OR of all the hash values should cover all the bits */
	KUNIT_EXPECT_EQ_MSG(test, string_or, -1u,
			    "OR of all string hash results = %#x != %#x",
			    string_or, -1u);
}

static void test_hash_or(struct kunit *test)
{
	char buf[SIZE+1];
	u32 hash_or[2][33] = { { 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 */
			KUNIT_EXPECT_EQ_MSG(test, hashlen_len(hashlen), j-i,
					    "hashlen_string(%d..%d) returned length %u, expected %d",
					    i, j, hashlen_len(hashlen), j-i);
			/* Check that the hashes match */
			KUNIT_EXPECT_EQ_MSG(test, hashlen_hash(hashlen), h0,
					    "hashlen_string(%d..%d) = %08x != full_name_hash() = %08x",
					    i, j, hashlen_hash(hashlen), h0);

			h64 = h64 << 32 | h0;	/* For use with hash_64 */
			test_int_hash(test, h64, hash_or);
		} /* i */
	} /* j */

	KUNIT_EXPECT_EQ_MSG(test, hash_or[0][0], -1u,
			    "OR of all __hash_32 results = %#x != %#x",
			    hash_or[0][0], -1u);
#ifdef HAVE_ARCH__HASH_32
#if HAVE_ARCH__HASH_32 != 1	/* Test is pointless if results match */
	KUNIT_EXPECT_EQ_MSG(test, hash_or[1][0], -1u,
			    "OR of all __hash_32_generic results = %#x != %#x",
			    hash_or[1][0], -1u);
#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 */

		KUNIT_EXPECT_EQ_MSG(test, hash_or[0][i], m,
				    "OR of all hash_32(%d) results = %#x (%#x expected)",
				    i, hash_or[0][i], m);
		KUNIT_EXPECT_EQ_MSG(test, hash_or[1][i], m,
				    "OR of all hash_64(%d) results = %#x (%#x expected)",
				    i, hash_or[1][i], m);
	}
}

static struct kunit_case hash_test_cases[] __refdata = {
	KUNIT_CASE(test_string_or),
	KUNIT_CASE(test_hash_or),
	{}
};

static struct kunit_suite hash_test_suite = {
	.name = "hash",
	.test_cases = hash_test_cases,
};


kunit_test_suite(hash_test_suite);

MODULE_LICENSE("GPL");
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
468a9428 GS	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
468a9428 GS	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>
0acc968f	22	#include <kunit/test.h>
468a9428 GS	23
468a9428 GS	24	/* 32-bit XORSHIFT generator. Seed must not be zero. */
0acc968f	25	static u32 __attribute_const__
468a9428 GS	26	xorshift(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. */
0acc968f	35	static u8 __attribute_const__
468a9428 GS	36	mod255(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. */
0acc968f	46	static void fill_buf(char *buf, size_t len, u32 seed)
468a9428 GS	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
ae788067 IB	56	/* Holds most testing variables for the int test. */
	57	struct 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
0acc968f IB	71	static void
0acc968f IB	72	test_int__hash_32(struct kunit test, struct test_hash_params params)
ae788067 IB	73	{
	74	params->hash_or[1][0] \|= params->h2 = __hash_32_generic(params->h0);
	75	#if HAVE_ARCH__HASH_32 == 1
0acc968f IB	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);
ae788067	79	#endif
ae788067 IB	80	}
	81	#endif
	82
	83	#ifdef HAVE_ARCH_HASH_64
0acc968f IB	84	static void
0acc968f IB	85	test_int_hash_64(struct kunit test, struct test_hash_params params, u32 const m, int k)
ae788067 IB	86	{
	87	params->h2 = hash_64_generic(params->h64, k);
	88	#if HAVE_ARCH_HASH_64 == 1
0acc968f IB	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);
ae788067	92	#else
0acc968f IB	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);
ae788067	96	#endif
ae788067 IB	97	}
	98	#endif
	99
468a9428 GS	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	*/
0acc968f IB	109	static void
0acc968f IB	110	test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33])
468a9428 GS	111	{
468a9428 GS	112	int k;
ae788067	113	struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or };
468a9428 GS	114
468a9428 GS	115	/* Test __hash32 */
ae788067	116	hash_or[0][0] \|= params.h1 = __hash_32(params.h0);
468a9428	117	#ifdef HAVE_ARCH__HASH_32
0acc968f	118	test_int__hash_32(test, &params);
468a9428 GS	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 */
ae788067	126	hash_or[0][k] \|= params.h1 = hash_32(params.h0, k);
0acc968f IB	127	KUNIT_EXPECT_LE_MSG(test, params.h1, m,
	128	"hash_32(%#x, %d) = %#x > %#x",
	129	params.h0, k, params.h1, m);
fd0a1462	130
468a9428	131	/* Test hash_64 */
ae788067	132	hash_or[1][k] \|= params.h1 = hash_64(h64, k);
0acc968f IB	133	KUNIT_EXPECT_LE_MSG(test, params.h1, m,
	134	"hash_64(%#llx, %d) = %#x > %#x",
	135	h64, k, params.h1, m);
468a9428	136	#ifdef HAVE_ARCH_HASH_64
0acc968f	137	test_int_hash_64(test, &params, &m, &k);
468a9428 GS	138	#endif
468a9428 GS	139	}
468a9428 GS	140	}
	141
	142	#define SIZE 256 /* Run time is cubic in SIZE */
	143
0acc968f	144	static void test_string_or(struct kunit *test)
468a9428 GS	145	{
468a9428 GS	146	char buf[SIZE+1];
5427d3d7 IB	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 */
0acc968f IB	164	KUNIT_EXPECT_EQ_MSG(test, string_or, -1u,
	165	"OR of all string hash results = %#x != %#x",
	166	string_or, -1u);
5427d3d7 IB	167	}
5427d3d7 IB	168
0acc968f	169	static void test_hash_or(struct kunit *test)
5427d3d7 IB	170	{
	171	char buf[SIZE+1];
	172	u32 hash_or[2][33] = { { 0, } };
468a9428 GS	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++) {
8387ff25 LT	183	u64 hashlen = hashlen_string(buf+i, buf+i);
8387ff25 LT	184	u32 h0 = full_name_hash(buf+i, buf+i, j-i);
468a9428 GS	185
468a9428 GS	186	/* Check that hashlen_string gets the length right */
0acc968f IB	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);
468a9428	190	/* Check that the hashes match */
0acc968f IB	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);
468a9428	194
468a9428	195	h64 = h64 << 32 \| h0; /* For use with hash_64 */
0acc968f	196	test_int_hash(test, h64, hash_or);
468a9428 GS	197	} /* i */
	198	} /* j */
	199
0acc968f IB	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);
468a9428 GS	203	#ifdef HAVE_ARCH__HASH_32
468a9428 GS	204	#if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */
0acc968f IB	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);
468a9428 GS	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
0acc968f IB	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);
468a9428	221	}
5427d3d7 IB	222	}
5427d3d7 IB	223
0acc968f IB	224	static struct kunit_case hash_test_cases[] __refdata = {
	225	KUNIT_CASE(test_string_or),
	226	KUNIT_CASE(test_hash_or),
	227	{}
	228	};
5427d3d7	229
0acc968f IB	230	static struct kunit_suite hash_test_suite = {
	231	.name = "hash",
	232	.test_cases = hash_test_cases,
	233	};
468a9428	234
468a9428	235
0acc968f	236	kunit_test_suite(hash_test_suite);
468a9428 GS	237
468a9428 GS	238	MODULE_LICENSE("GPL");