cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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test_hash.c (6683B)


      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");