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![Jason A. Donenfeld](/assets/img/avatar_default.png)
HalfSipHash, or hsiphash, is a shortened version of SipHash, which generates 32-bit outputs using a weaker 64-bit key. It has *much* lower security margins, and shouldn't be used for anything too sensitive, but it could be used as a hashtable key function replacement, if the output is never exposed, and if the security requirement is not too high. The goal is to make this something that performance-critical jhash users would be willing to use. On 64-bit machines, HalfSipHash1-3 is slower than SipHash1-3, so we alias SipHash1-3 to HalfSipHash1-3 on those systems. 64-bit x86_64: [ 0.509409] test_siphash: SipHash2-4 cycles: 4049181 [ 0.510650] test_siphash: SipHash1-3 cycles: 2512884 [ 0.512205] test_siphash: HalfSipHash1-3 cycles: 3429920 [ 0.512904] test_siphash: JenkinsHash cycles: 978267 So, we map hsiphash() -> SipHash1-3 32-bit x86: [ 0.509868] test_siphash: SipHash2-4 cycles: 14812892 [ 0.513601] test_siphash: SipHash1-3 cycles: 9510710 [ 0.515263] test_siphash: HalfSipHash1-3 cycles: 3856157 [ 0.515952] test_siphash: JenkinsHash cycles: 1148567 So, we map hsiphash() -> HalfSipHash1-3 hsiphash() is roughly 3 times slower than jhash(), but comes with a considerable security improvement. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
551 lines
12 KiB
C
551 lines
12 KiB
C
/* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*
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* This file is provided under a dual BSD/GPLv2 license.
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*
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* SipHash: a fast short-input PRF
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* https://131002.net/siphash/
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*
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* This implementation is specifically for SipHash2-4 for a secure PRF
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* and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
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* hashtables.
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*/
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#include <linux/siphash.h>
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#include <asm/unaligned.h>
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#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
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#include <linux/dcache.h>
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#include <asm/word-at-a-time.h>
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#endif
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#define SIPROUND \
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do { \
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v0 += v1; v1 = rol64(v1, 13); v1 ^= v0; v0 = rol64(v0, 32); \
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v2 += v3; v3 = rol64(v3, 16); v3 ^= v2; \
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v0 += v3; v3 = rol64(v3, 21); v3 ^= v0; \
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v2 += v1; v1 = rol64(v1, 17); v1 ^= v2; v2 = rol64(v2, 32); \
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} while (0)
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#define PREAMBLE(len) \
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u64 v0 = 0x736f6d6570736575ULL; \
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u64 v1 = 0x646f72616e646f6dULL; \
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u64 v2 = 0x6c7967656e657261ULL; \
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u64 v3 = 0x7465646279746573ULL; \
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u64 b = ((u64)(len)) << 56; \
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v3 ^= key->key[1]; \
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v2 ^= key->key[0]; \
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v1 ^= key->key[1]; \
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v0 ^= key->key[0];
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#define POSTAMBLE \
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v3 ^= b; \
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SIPROUND; \
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SIPROUND; \
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v0 ^= b; \
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v2 ^= 0xff; \
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SIPROUND; \
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SIPROUND; \
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SIPROUND; \
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SIPROUND; \
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return (v0 ^ v1) ^ (v2 ^ v3);
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u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key)
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{
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const u8 *end = data + len - (len % sizeof(u64));
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const u8 left = len & (sizeof(u64) - 1);
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u64 m;
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PREAMBLE(len)
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for (; data != end; data += sizeof(u64)) {
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m = le64_to_cpup(data);
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v3 ^= m;
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SIPROUND;
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SIPROUND;
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v0 ^= m;
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}
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#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
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if (left)
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b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
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bytemask_from_count(left)));
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#else
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switch (left) {
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case 7: b |= ((u64)end[6]) << 48;
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case 6: b |= ((u64)end[5]) << 40;
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case 5: b |= ((u64)end[4]) << 32;
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case 4: b |= le32_to_cpup(data); break;
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case 3: b |= ((u64)end[2]) << 16;
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case 2: b |= le16_to_cpup(data); break;
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case 1: b |= end[0];
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}
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#endif
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POSTAMBLE
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}
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EXPORT_SYMBOL(__siphash_aligned);
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#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key)
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{
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const u8 *end = data + len - (len % sizeof(u64));
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const u8 left = len & (sizeof(u64) - 1);
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u64 m;
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PREAMBLE(len)
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for (; data != end; data += sizeof(u64)) {
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m = get_unaligned_le64(data);
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v3 ^= m;
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SIPROUND;
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SIPROUND;
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v0 ^= m;
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}
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#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
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if (left)
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b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
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bytemask_from_count(left)));
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#else
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switch (left) {
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case 7: b |= ((u64)end[6]) << 48;
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case 6: b |= ((u64)end[5]) << 40;
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case 5: b |= ((u64)end[4]) << 32;
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case 4: b |= get_unaligned_le32(end); break;
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case 3: b |= ((u64)end[2]) << 16;
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case 2: b |= get_unaligned_le16(end); break;
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case 1: b |= end[0];
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}
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#endif
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POSTAMBLE
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}
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EXPORT_SYMBOL(__siphash_unaligned);
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#endif
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/**
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* siphash_1u64 - compute 64-bit siphash PRF value of a u64
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* @first: first u64
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* @key: the siphash key
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*/
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u64 siphash_1u64(const u64 first, const siphash_key_t *key)
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{
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PREAMBLE(8)
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v3 ^= first;
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SIPROUND;
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SIPROUND;
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v0 ^= first;
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POSTAMBLE
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}
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EXPORT_SYMBOL(siphash_1u64);
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/**
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* siphash_2u64 - compute 64-bit siphash PRF value of 2 u64
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* @first: first u64
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* @second: second u64
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* @key: the siphash key
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*/
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u64 siphash_2u64(const u64 first, const u64 second, const siphash_key_t *key)
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{
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PREAMBLE(16)
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v3 ^= first;
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SIPROUND;
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SIPROUND;
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v0 ^= first;
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v3 ^= second;
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SIPROUND;
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SIPROUND;
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v0 ^= second;
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POSTAMBLE
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}
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EXPORT_SYMBOL(siphash_2u64);
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/**
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* siphash_3u64 - compute 64-bit siphash PRF value of 3 u64
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* @first: first u64
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* @second: second u64
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* @third: third u64
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* @key: the siphash key
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*/
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u64 siphash_3u64(const u64 first, const u64 second, const u64 third,
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const siphash_key_t *key)
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{
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PREAMBLE(24)
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v3 ^= first;
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SIPROUND;
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SIPROUND;
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v0 ^= first;
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v3 ^= second;
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SIPROUND;
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SIPROUND;
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v0 ^= second;
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v3 ^= third;
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SIPROUND;
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SIPROUND;
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v0 ^= third;
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POSTAMBLE
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}
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EXPORT_SYMBOL(siphash_3u64);
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/**
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* siphash_4u64 - compute 64-bit siphash PRF value of 4 u64
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* @first: first u64
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* @second: second u64
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* @third: third u64
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* @forth: forth u64
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* @key: the siphash key
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*/
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u64 siphash_4u64(const u64 first, const u64 second, const u64 third,
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const u64 forth, const siphash_key_t *key)
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{
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PREAMBLE(32)
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v3 ^= first;
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SIPROUND;
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SIPROUND;
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v0 ^= first;
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v3 ^= second;
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SIPROUND;
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SIPROUND;
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v0 ^= second;
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v3 ^= third;
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SIPROUND;
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SIPROUND;
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v0 ^= third;
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v3 ^= forth;
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SIPROUND;
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SIPROUND;
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v0 ^= forth;
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POSTAMBLE
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}
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EXPORT_SYMBOL(siphash_4u64);
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u64 siphash_1u32(const u32 first, const siphash_key_t *key)
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{
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PREAMBLE(4)
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b |= first;
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POSTAMBLE
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}
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EXPORT_SYMBOL(siphash_1u32);
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u64 siphash_3u32(const u32 first, const u32 second, const u32 third,
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const siphash_key_t *key)
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{
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u64 combined = (u64)second << 32 | first;
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PREAMBLE(12)
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v3 ^= combined;
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SIPROUND;
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SIPROUND;
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v0 ^= combined;
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b |= third;
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POSTAMBLE
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}
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EXPORT_SYMBOL(siphash_3u32);
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#if BITS_PER_LONG == 64
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/* Note that on 64-bit, we make HalfSipHash1-3 actually be SipHash1-3, for
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* performance reasons. On 32-bit, below, we actually implement HalfSipHash1-3.
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*/
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#define HSIPROUND SIPROUND
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#define HPREAMBLE(len) PREAMBLE(len)
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#define HPOSTAMBLE \
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v3 ^= b; \
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HSIPROUND; \
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v0 ^= b; \
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v2 ^= 0xff; \
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HSIPROUND; \
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HSIPROUND; \
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HSIPROUND; \
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return (v0 ^ v1) ^ (v2 ^ v3);
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u32 __hsiphash_aligned(const void *data, size_t len, const hsiphash_key_t *key)
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{
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const u8 *end = data + len - (len % sizeof(u64));
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const u8 left = len & (sizeof(u64) - 1);
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u64 m;
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HPREAMBLE(len)
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for (; data != end; data += sizeof(u64)) {
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m = le64_to_cpup(data);
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v3 ^= m;
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HSIPROUND;
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v0 ^= m;
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}
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#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
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if (left)
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b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
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bytemask_from_count(left)));
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#else
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switch (left) {
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case 7: b |= ((u64)end[6]) << 48;
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case 6: b |= ((u64)end[5]) << 40;
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case 5: b |= ((u64)end[4]) << 32;
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case 4: b |= le32_to_cpup(data); break;
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case 3: b |= ((u64)end[2]) << 16;
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case 2: b |= le16_to_cpup(data); break;
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case 1: b |= end[0];
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}
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#endif
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(__hsiphash_aligned);
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#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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u32 __hsiphash_unaligned(const void *data, size_t len,
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const hsiphash_key_t *key)
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{
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const u8 *end = data + len - (len % sizeof(u64));
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const u8 left = len & (sizeof(u64) - 1);
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u64 m;
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HPREAMBLE(len)
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for (; data != end; data += sizeof(u64)) {
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m = get_unaligned_le64(data);
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v3 ^= m;
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HSIPROUND;
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v0 ^= m;
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}
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#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
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if (left)
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b |= le64_to_cpu((__force __le64)(load_unaligned_zeropad(data) &
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bytemask_from_count(left)));
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#else
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switch (left) {
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case 7: b |= ((u64)end[6]) << 48;
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case 6: b |= ((u64)end[5]) << 40;
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case 5: b |= ((u64)end[4]) << 32;
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case 4: b |= get_unaligned_le32(end); break;
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case 3: b |= ((u64)end[2]) << 16;
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case 2: b |= get_unaligned_le16(end); break;
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case 1: b |= end[0];
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}
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#endif
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(__hsiphash_unaligned);
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#endif
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/**
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* hsiphash_1u32 - compute 64-bit hsiphash PRF value of a u32
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* @first: first u32
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* @key: the hsiphash key
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*/
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u32 hsiphash_1u32(const u32 first, const hsiphash_key_t *key)
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{
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HPREAMBLE(4)
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b |= first;
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(hsiphash_1u32);
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/**
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* hsiphash_2u32 - compute 32-bit hsiphash PRF value of 2 u32
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* @first: first u32
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* @second: second u32
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* @key: the hsiphash key
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*/
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u32 hsiphash_2u32(const u32 first, const u32 second, const hsiphash_key_t *key)
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{
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u64 combined = (u64)second << 32 | first;
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HPREAMBLE(8)
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v3 ^= combined;
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HSIPROUND;
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v0 ^= combined;
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(hsiphash_2u32);
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/**
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* hsiphash_3u32 - compute 32-bit hsiphash PRF value of 3 u32
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* @first: first u32
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* @second: second u32
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* @third: third u32
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* @key: the hsiphash key
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*/
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u32 hsiphash_3u32(const u32 first, const u32 second, const u32 third,
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const hsiphash_key_t *key)
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{
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u64 combined = (u64)second << 32 | first;
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HPREAMBLE(12)
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v3 ^= combined;
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HSIPROUND;
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v0 ^= combined;
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b |= third;
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(hsiphash_3u32);
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/**
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* hsiphash_4u32 - compute 32-bit hsiphash PRF value of 4 u32
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* @first: first u32
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* @second: second u32
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* @third: third u32
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* @forth: forth u32
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* @key: the hsiphash key
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*/
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u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third,
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const u32 forth, const hsiphash_key_t *key)
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{
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u64 combined = (u64)second << 32 | first;
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HPREAMBLE(16)
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v3 ^= combined;
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HSIPROUND;
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v0 ^= combined;
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combined = (u64)forth << 32 | third;
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v3 ^= combined;
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HSIPROUND;
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v0 ^= combined;
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(hsiphash_4u32);
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#else
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#define HSIPROUND \
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do { \
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v0 += v1; v1 = rol32(v1, 5); v1 ^= v0; v0 = rol32(v0, 16); \
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v2 += v3; v3 = rol32(v3, 8); v3 ^= v2; \
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v0 += v3; v3 = rol32(v3, 7); v3 ^= v0; \
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v2 += v1; v1 = rol32(v1, 13); v1 ^= v2; v2 = rol32(v2, 16); \
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} while (0)
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#define HPREAMBLE(len) \
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u32 v0 = 0; \
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u32 v1 = 0; \
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u32 v2 = 0x6c796765U; \
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u32 v3 = 0x74656462U; \
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u32 b = ((u32)(len)) << 24; \
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v3 ^= key->key[1]; \
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v2 ^= key->key[0]; \
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v1 ^= key->key[1]; \
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v0 ^= key->key[0];
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#define HPOSTAMBLE \
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v3 ^= b; \
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HSIPROUND; \
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v0 ^= b; \
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v2 ^= 0xff; \
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HSIPROUND; \
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HSIPROUND; \
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HSIPROUND; \
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return v1 ^ v3;
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u32 __hsiphash_aligned(const void *data, size_t len, const hsiphash_key_t *key)
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{
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const u8 *end = data + len - (len % sizeof(u32));
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const u8 left = len & (sizeof(u32) - 1);
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u32 m;
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HPREAMBLE(len)
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for (; data != end; data += sizeof(u32)) {
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m = le32_to_cpup(data);
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v3 ^= m;
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HSIPROUND;
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v0 ^= m;
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}
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switch (left) {
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case 3: b |= ((u32)end[2]) << 16;
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case 2: b |= le16_to_cpup(data); break;
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case 1: b |= end[0];
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}
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HPOSTAMBLE
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}
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EXPORT_SYMBOL(__hsiphash_aligned);
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#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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u32 __hsiphash_unaligned(const void *data, size_t len,
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const hsiphash_key_t *key)
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{
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const u8 *end = data + len - (len % sizeof(u32));
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const u8 left = len & (sizeof(u32) - 1);
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u32 m;
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HPREAMBLE(len)
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for (; data != end; data += sizeof(u32)) {
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m = get_unaligned_le32(data);
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v3 ^= m;
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HSIPROUND;
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v0 ^= m;
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}
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switch (left) {
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case 3: b |= ((u32)end[2]) << 16;
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|
case 2: b |= get_unaligned_le16(end); break;
|
|
case 1: b |= end[0];
|
|
}
|
|
HPOSTAMBLE
|
|
}
|
|
EXPORT_SYMBOL(__hsiphash_unaligned);
|
|
#endif
|
|
|
|
/**
|
|
* hsiphash_1u32 - compute 32-bit hsiphash PRF value of a u32
|
|
* @first: first u32
|
|
* @key: the hsiphash key
|
|
*/
|
|
u32 hsiphash_1u32(const u32 first, const hsiphash_key_t *key)
|
|
{
|
|
HPREAMBLE(4)
|
|
v3 ^= first;
|
|
HSIPROUND;
|
|
v0 ^= first;
|
|
HPOSTAMBLE
|
|
}
|
|
EXPORT_SYMBOL(hsiphash_1u32);
|
|
|
|
/**
|
|
* hsiphash_2u32 - compute 32-bit hsiphash PRF value of 2 u32
|
|
* @first: first u32
|
|
* @second: second u32
|
|
* @key: the hsiphash key
|
|
*/
|
|
u32 hsiphash_2u32(const u32 first, const u32 second, const hsiphash_key_t *key)
|
|
{
|
|
HPREAMBLE(8)
|
|
v3 ^= first;
|
|
HSIPROUND;
|
|
v0 ^= first;
|
|
v3 ^= second;
|
|
HSIPROUND;
|
|
v0 ^= second;
|
|
HPOSTAMBLE
|
|
}
|
|
EXPORT_SYMBOL(hsiphash_2u32);
|
|
|
|
/**
|
|
* hsiphash_3u32 - compute 32-bit hsiphash PRF value of 3 u32
|
|
* @first: first u32
|
|
* @second: second u32
|
|
* @third: third u32
|
|
* @key: the hsiphash key
|
|
*/
|
|
u32 hsiphash_3u32(const u32 first, const u32 second, const u32 third,
|
|
const hsiphash_key_t *key)
|
|
{
|
|
HPREAMBLE(12)
|
|
v3 ^= first;
|
|
HSIPROUND;
|
|
v0 ^= first;
|
|
v3 ^= second;
|
|
HSIPROUND;
|
|
v0 ^= second;
|
|
v3 ^= third;
|
|
HSIPROUND;
|
|
v0 ^= third;
|
|
HPOSTAMBLE
|
|
}
|
|
EXPORT_SYMBOL(hsiphash_3u32);
|
|
|
|
/**
|
|
* hsiphash_4u32 - compute 32-bit hsiphash PRF value of 4 u32
|
|
* @first: first u32
|
|
* @second: second u32
|
|
* @third: third u32
|
|
* @forth: forth u32
|
|
* @key: the hsiphash key
|
|
*/
|
|
u32 hsiphash_4u32(const u32 first, const u32 second, const u32 third,
|
|
const u32 forth, const hsiphash_key_t *key)
|
|
{
|
|
HPREAMBLE(16)
|
|
v3 ^= first;
|
|
HSIPROUND;
|
|
v0 ^= first;
|
|
v3 ^= second;
|
|
HSIPROUND;
|
|
v0 ^= second;
|
|
v3 ^= third;
|
|
HSIPROUND;
|
|
v0 ^= third;
|
|
v3 ^= forth;
|
|
HSIPROUND;
|
|
v0 ^= forth;
|
|
HPOSTAMBLE
|
|
}
|
|
EXPORT_SYMBOL(hsiphash_4u32);
|
|
#endif
|