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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * Network checksum routines | |
4 | * | |
5 | * Copyright (C) 1999, 2003 Hewlett-Packard Co | |
6 | * Stephane Eranian <eranian@hpl.hp.com> | |
7 | * | |
8 | * Most of the code coming from arch/alpha/lib/checksum.c | |
9 | * | |
10 | * This file contains network checksum routines that are better done | |
11 | * in an architecture-specific manner due to speed.. | |
12 | */ | |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/string.h> | |
16 | ||
17 | #include <asm/byteorder.h> | |
18 | ||
19 | static inline unsigned short | |
20 | from64to16 (unsigned long x) | |
21 | { | |
22 | /* add up 32-bit words for 33 bits */ | |
23 | x = (x & 0xffffffff) + (x >> 32); | |
24 | /* add up 16-bit and 17-bit words for 17+c bits */ | |
25 | x = (x & 0xffff) + (x >> 16); | |
26 | /* add up 16-bit and 2-bit for 16+c bit */ | |
27 | x = (x & 0xffff) + (x >> 16); | |
28 | /* add up carry.. */ | |
29 | x = (x & 0xffff) + (x >> 16); | |
30 | return x; | |
31 | } | |
32 | ||
33 | /* | |
34 | * computes the checksum of the TCP/UDP pseudo-header | |
35 | * returns a 16-bit checksum, already complemented. | |
36 | */ | |
32252996 | 37 | __sum16 |
01cfbad7 AD |
38 | csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, |
39 | __u8 proto, __wsum sum) | |
1da177e4 | 40 | { |
32252996 AV |
41 | return (__force __sum16)~from64to16( |
42 | (__force u64)saddr + (__force u64)daddr + | |
43 | (__force u64)sum + ((len + proto) << 8)); | |
1da177e4 LT |
44 | } |
45 | ||
46 | EXPORT_SYMBOL(csum_tcpudp_magic); | |
47 | ||
32252996 | 48 | __wsum |
01cfbad7 AD |
49 | csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, |
50 | __u8 proto, __wsum sum) | |
1da177e4 LT |
51 | { |
52 | unsigned long result; | |
53 | ||
32252996 AV |
54 | result = (__force u64)saddr + (__force u64)daddr + |
55 | (__force u64)sum + ((len + proto) << 8); | |
1da177e4 LT |
56 | |
57 | /* Fold down to 32-bits so we don't lose in the typedef-less network stack. */ | |
58 | /* 64 to 33 */ | |
59 | result = (result & 0xffffffff) + (result >> 32); | |
60 | /* 33 to 32 */ | |
61 | result = (result & 0xffffffff) + (result >> 32); | |
32252996 | 62 | return (__force __wsum)result; |
1da177e4 | 63 | } |
547c178b | 64 | EXPORT_SYMBOL(csum_tcpudp_nofold); |
1da177e4 LT |
65 | |
66 | extern unsigned long do_csum (const unsigned char *, long); | |
67 | ||
68 | /* | |
69 | * computes the checksum of a memory block at buff, length len, | |
70 | * and adds in "sum" (32-bit) | |
71 | * | |
72 | * returns a 32-bit number suitable for feeding into itself | |
73 | * or csum_tcpudp_magic | |
74 | * | |
75 | * this function must be called with even lengths, except | |
76 | * for the last fragment, which may be odd | |
77 | * | |
78 | * it's best to have buff aligned on a 32-bit boundary | |
79 | */ | |
32252996 | 80 | __wsum csum_partial(const void *buff, int len, __wsum sum) |
1da177e4 | 81 | { |
32252996 | 82 | u64 result = do_csum(buff, len); |
1da177e4 LT |
83 | |
84 | /* add in old sum, and carry.. */ | |
32252996 | 85 | result += (__force u32)sum; |
1da177e4 LT |
86 | /* 32+c bits -> 32 bits */ |
87 | result = (result & 0xffffffff) + (result >> 32); | |
32252996 | 88 | return (__force __wsum)result; |
1da177e4 LT |
89 | } |
90 | ||
91 | EXPORT_SYMBOL(csum_partial); | |
92 | ||
93 | /* | |
94 | * this routine is used for miscellaneous IP-like checksums, mainly | |
95 | * in icmp.c | |
96 | */ | |
32252996 | 97 | __sum16 ip_compute_csum (const void *buff, int len) |
1da177e4 | 98 | { |
32252996 | 99 | return (__force __sum16)~do_csum(buff,len); |
1da177e4 LT |
100 | } |
101 | ||
102 | EXPORT_SYMBOL(ip_compute_csum); |