1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Network checksum routines
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 1999, 2003 Hewlett-Packard Co
6*4882a593Smuzhiyun * Stephane Eranian <eranian@hpl.hp.com>
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * Most of the code coming from arch/alpha/lib/checksum.c
9*4882a593Smuzhiyun *
10*4882a593Smuzhiyun * This file contains network checksum routines that are better done
11*4882a593Smuzhiyun * in an architecture-specific manner due to speed..
12*4882a593Smuzhiyun */
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun #include <linux/module.h>
15*4882a593Smuzhiyun #include <linux/string.h>
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #include <asm/byteorder.h>
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun static inline unsigned short
from64to16(unsigned long x)20*4882a593Smuzhiyun from64to16 (unsigned long x)
21*4882a593Smuzhiyun {
22*4882a593Smuzhiyun /* add up 32-bit words for 33 bits */
23*4882a593Smuzhiyun x = (x & 0xffffffff) + (x >> 32);
24*4882a593Smuzhiyun /* add up 16-bit and 17-bit words for 17+c bits */
25*4882a593Smuzhiyun x = (x & 0xffff) + (x >> 16);
26*4882a593Smuzhiyun /* add up 16-bit and 2-bit for 16+c bit */
27*4882a593Smuzhiyun x = (x & 0xffff) + (x >> 16);
28*4882a593Smuzhiyun /* add up carry.. */
29*4882a593Smuzhiyun x = (x & 0xffff) + (x >> 16);
30*4882a593Smuzhiyun return x;
31*4882a593Smuzhiyun }
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun /*
34*4882a593Smuzhiyun * computes the checksum of the TCP/UDP pseudo-header
35*4882a593Smuzhiyun * returns a 16-bit checksum, already complemented.
36*4882a593Smuzhiyun */
37*4882a593Smuzhiyun __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)38*4882a593Smuzhiyun csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
39*4882a593Smuzhiyun __u8 proto, __wsum sum)
40*4882a593Smuzhiyun {
41*4882a593Smuzhiyun return (__force __sum16)~from64to16(
42*4882a593Smuzhiyun (__force u64)saddr + (__force u64)daddr +
43*4882a593Smuzhiyun (__force u64)sum + ((len + proto) << 8));
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun EXPORT_SYMBOL(csum_tcpudp_magic);
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun __wsum
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)49*4882a593Smuzhiyun csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
50*4882a593Smuzhiyun __u8 proto, __wsum sum)
51*4882a593Smuzhiyun {
52*4882a593Smuzhiyun unsigned long result;
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun result = (__force u64)saddr + (__force u64)daddr +
55*4882a593Smuzhiyun (__force u64)sum + ((len + proto) << 8);
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun /* Fold down to 32-bits so we don't lose in the typedef-less network stack. */
58*4882a593Smuzhiyun /* 64 to 33 */
59*4882a593Smuzhiyun result = (result & 0xffffffff) + (result >> 32);
60*4882a593Smuzhiyun /* 33 to 32 */
61*4882a593Smuzhiyun result = (result & 0xffffffff) + (result >> 32);
62*4882a593Smuzhiyun return (__force __wsum)result;
63*4882a593Smuzhiyun }
64*4882a593Smuzhiyun EXPORT_SYMBOL(csum_tcpudp_nofold);
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun extern unsigned long do_csum (const unsigned char *, long);
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun /*
69*4882a593Smuzhiyun * computes the checksum of a memory block at buff, length len,
70*4882a593Smuzhiyun * and adds in "sum" (32-bit)
71*4882a593Smuzhiyun *
72*4882a593Smuzhiyun * returns a 32-bit number suitable for feeding into itself
73*4882a593Smuzhiyun * or csum_tcpudp_magic
74*4882a593Smuzhiyun *
75*4882a593Smuzhiyun * this function must be called with even lengths, except
76*4882a593Smuzhiyun * for the last fragment, which may be odd
77*4882a593Smuzhiyun *
78*4882a593Smuzhiyun * it's best to have buff aligned on a 32-bit boundary
79*4882a593Smuzhiyun */
csum_partial(const void * buff,int len,__wsum sum)80*4882a593Smuzhiyun __wsum csum_partial(const void *buff, int len, __wsum sum)
81*4882a593Smuzhiyun {
82*4882a593Smuzhiyun u64 result = do_csum(buff, len);
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun /* add in old sum, and carry.. */
85*4882a593Smuzhiyun result += (__force u32)sum;
86*4882a593Smuzhiyun /* 32+c bits -> 32 bits */
87*4882a593Smuzhiyun result = (result & 0xffffffff) + (result >> 32);
88*4882a593Smuzhiyun return (__force __wsum)result;
89*4882a593Smuzhiyun }
90*4882a593Smuzhiyun
91*4882a593Smuzhiyun EXPORT_SYMBOL(csum_partial);
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun /*
94*4882a593Smuzhiyun * this routine is used for miscellaneous IP-like checksums, mainly
95*4882a593Smuzhiyun * in icmp.c
96*4882a593Smuzhiyun */
ip_compute_csum(const void * buff,int len)97*4882a593Smuzhiyun __sum16 ip_compute_csum (const void *buff, int len)
98*4882a593Smuzhiyun {
99*4882a593Smuzhiyun return (__force __sum16)~do_csum(buff,len);
100*4882a593Smuzhiyun }
101*4882a593Smuzhiyun
102*4882a593Smuzhiyun EXPORT_SYMBOL(ip_compute_csum);
103