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,
95                   unsigned short len, unsigned short proto,
96                   __wsum sum)
97{
98	__u32 csum = (__force __u32)sum;
99
100	csum += (__force __u32)saddr;
101	if (csum < (__force __u32)saddr)
102		csum++;
103
104	csum += (__force __u32)daddr;
105	if (csum < (__force __u32)daddr)
106		csum++;
107
108	csum += len + proto;
109	if (csum < len + proto)
110		csum++;
111
112	return (__force __wsum)csum;
113}
114
115/*
116 * computes the checksum of the TCP/UDP pseudo-header
117 * returns a 16-bit checksum, already complemented
118 */
119
120static inline __sum16
121csum_tcpudp_magic(__be32 saddr, __be32 daddr,
122                  unsigned short len, unsigned short proto,
123                  __wsum sum)
124{
125	return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
126}
127
128/*
129 * this routine is used for miscellaneous IP-like checksums, mainly
130 * in icmp.c
131 */
132
133static inline __sum16 ip_compute_csum(const void *buff, int len)
134{
135	return csum_fold(csum_partial(buff, len, 0));
136}
137
138#endif /* _S390_CHECKSUM_H */
139
140
141