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1/*
2 * S390 fast network checksum routines
3 *
4 * S390 version
5 * Copyright IBM Corp. 1999
6 * Author(s): Ulrich Hild (first version)
7 * Martin Schwidefsky (heavily optimized CKSM version)
8 * D.J. Barrow (third attempt)
9 */
10
11#ifndef _S390_CHECKSUM_H
12#define _S390_CHECKSUM_H
13
14#include <asm/uaccess.h>
15
16/*
17 * computes the checksum of a memory block at buff, length len,
18 * and adds in "sum" (32-bit)
19 *
20 * returns a 32-bit number suitable for feeding into itself
21 * or csum_tcpudp_magic
22 *
23 * this function must be called with even lengths, except
24 * for the last fragment, which may be odd
25 *
26 * it's best to have buff aligned on a 32-bit boundary
27 */
28static inline __wsum
29csum_partial(const void *buff, int len, __wsum sum)
30{
31 register unsigned long reg2 asm("2") = (unsigned long) buff;
32 register unsigned long reg3 asm("3") = (unsigned long) len;
33
34 asm volatile(
35 "0: cksm %0,%1\n" /* do checksum on longs */
36 " jo 0b\n"
37 : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
38 return sum;
39}
40
41/*
42 * the same as csum_partial_copy, but copies from user space.
43 *
44 * here even more important to align src and dst on a 32-bit (or even
45 * better 64-bit) boundary
46 *
47 * Copy from userspace and compute checksum.
48 */
49static inline __wsum
50csum_partial_copy_from_user(const void __user *src, void *dst,
51 int len, __wsum sum,
52 int *err_ptr)
53{
54 if (unlikely(copy_from_user(dst, src, len)))
55 *err_ptr = -EFAULT;
56 return csum_partial(dst, len, sum);
57}
58
59
60static inline __wsum
61csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
62{
63 memcpy(dst,src,len);
64 return csum_partial(dst, len, sum);
65}
66
67/*
68 * Fold a partial checksum without adding pseudo headers
69 */
70static inline __sum16 csum_fold(__wsum sum)
71{
72 u32 csum = (__force u32) sum;
73
74 csum += (csum >> 16) + (csum << 16);
75 csum >>= 16;
76 return (__force __sum16) ~csum;
77}
78
79/*
80 * This is a version of ip_compute_csum() optimized for IP headers,
81 * which always checksum on 4 octet boundaries.
82 *
83 */
84static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
85{
86 return csum_fold(csum_partial(iph, ihl*4, 0));
87}
88
89/*
90 * computes the checksum of the TCP/UDP pseudo-header
91 * returns a 32-bit checksum
92 */
93static inline __wsum
94csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
95 __wsum sum)
96{
97 __u32 csum = (__force __u32)sum;
98
99 csum += (__force __u32)saddr;
100 if (csum < (__force __u32)saddr)
101 csum++;
102
103 csum += (__force __u32)daddr;
104 if (csum < (__force __u32)daddr)
105 csum++;
106
107 csum += len + proto;
108 if (csum < len + proto)
109 csum++;
110
111 return (__force __wsum)csum;
112}
113
114/*
115 * computes the checksum of the TCP/UDP pseudo-header
116 * returns a 16-bit checksum, already complemented
117 */
118
119static inline __sum16
120csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
121 __wsum sum)
122{
123 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
124}
125
126/*
127 * this routine is used for miscellaneous IP-like checksums, mainly
128 * in icmp.c
129 */
130
131static inline __sum16 ip_compute_csum(const void *buff, int len)
132{
133 return csum_fold(csum_partial(buff, len, 0));
134}
135
136#endif /* _S390_CHECKSUM_H */
137
138