1 #ifndef _S390_CHECKSUM_H
2 #define _S390_CHECKSUM_H
3
4 /*
5 * include/asm-s390/checksum.h
6 * S390 fast network checksum routines
7 * see also arch/S390/lib/checksum.c
8 *
9 * S390 version
10 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
11 * Author(s): Ulrich Hild (first version)
12 * Martin Schwidefsky (heavily optimized CKSM version)
13 * D.J. Barrow (third attempt)
14 */
15
16 #include <asm/uaccess.h>
17
18 /*
19 * computes the checksum of a memory block at buff, length len,
20 * and adds in "sum" (32-bit)
21 *
22 * returns a 32-bit number suitable for feeding into itself
23 * or csum_tcpudp_magic
24 *
25 * this function must be called with even lengths, except
26 * for the last fragment, which may be odd
27 *
28 * it's best to have buff aligned on a 32-bit boundary
29 */
30 static inline __wsum
csum_partial(const void * buff,int len,__wsum sum)31 csum_partial(const void *buff, int len, __wsum sum)
32 {
33 register unsigned long reg2 asm("2") = (unsigned long) buff;
34 register unsigned long reg3 asm("3") = (unsigned long) len;
35
36 asm volatile(
37 "0: cksm %0,%1\n" /* do checksum on longs */
38 " jo 0b\n"
39 : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
40 return sum;
41 }
42
43 /*
44 * the same as csum_partial_copy, but copies from user space.
45 *
46 * here even more important to align src and dst on a 32-bit (or even
47 * better 64-bit) boundary
48 *
49 * Copy from userspace and compute checksum. If we catch an exception
50 * then zero the rest of the buffer.
51 */
52 static inline __wsum
csum_partial_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)53 csum_partial_copy_from_user(const void __user *src, void *dst,
54 int len, __wsum sum,
55 int *err_ptr)
56 {
57 int missing;
58
59 missing = copy_from_user(dst, src, len);
60 if (missing) {
61 memset(dst + len - missing, 0, missing);
62 *err_ptr = -EFAULT;
63 }
64
65 return csum_partial(dst, len, sum);
66 }
67
68
69 static inline __wsum
csum_partial_copy_nocheck(const void * src,void * dst,int len,__wsum sum)70 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
71 {
72 memcpy(dst,src,len);
73 return csum_partial(dst, len, sum);
74 }
75
76 /*
77 * Fold a partial checksum without adding pseudo headers
78 */
csum_fold(__wsum sum)79 static inline __sum16 csum_fold(__wsum sum)
80 {
81 u32 csum = (__force u32) sum;
82
83 csum += (csum >> 16) + (csum << 16);
84 csum >>= 16;
85 return (__force __sum16) ~csum;
86 }
87
88 /*
89 * This is a version of ip_compute_csum() optimized for IP headers,
90 * which always checksum on 4 octet boundaries.
91 *
92 */
ip_fast_csum(const void * iph,unsigned int ihl)93 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
94 {
95 return csum_fold(csum_partial(iph, ihl*4, 0));
96 }
97
98 /*
99 * computes the checksum of the TCP/UDP pseudo-header
100 * returns a 32-bit checksum
101 */
102 static inline __wsum
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)103 csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
104 unsigned short len, unsigned short proto,
105 __wsum sum)
106 {
107 __u32 csum = (__force __u32)sum;
108
109 csum += (__force __u32)saddr;
110 if (csum < (__force __u32)saddr)
111 csum++;
112
113 csum += (__force __u32)daddr;
114 if (csum < (__force __u32)daddr)
115 csum++;
116
117 csum += len + proto;
118 if (csum < len + proto)
119 csum++;
120
121 return (__force __wsum)csum;
122 }
123
124 /*
125 * computes the checksum of the TCP/UDP pseudo-header
126 * returns a 16-bit checksum, already complemented
127 */
128
129 static inline __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)130 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
131 unsigned short len, unsigned short proto,
132 __wsum sum)
133 {
134 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
135 }
136
137 /*
138 * this routine is used for miscellaneous IP-like checksums, mainly
139 * in icmp.c
140 */
141
ip_compute_csum(const void * buff,int len)142 static inline __sum16 ip_compute_csum(const void *buff, int len)
143 {
144 return csum_fold(csum_partial(buff, len, 0));
145 }
146
147 #endif /* _S390_CHECKSUM_H */
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