1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * S390 fast network checksum routines
4 *
5 * S390 version
6 * Copyright IBM Corp. 1999
7 * Author(s): Ulrich Hild (first version)
8 * Martin Schwidefsky (heavily optimized CKSM version)
9 * D.J. Barrow (third attempt)
10 */
11
12 #ifndef _S390_CHECKSUM_H
13 #define _S390_CHECKSUM_H
14
15 #include <linux/uaccess.h>
16
17 /*
18 * computes the checksum of a memory block at buff, length len,
19 * and adds in "sum" (32-bit)
20 *
21 * returns a 32-bit number suitable for feeding into itself
22 * or csum_tcpudp_magic
23 *
24 * this function must be called with even lengths, except
25 * for the last fragment, which may be odd
26 *
27 * it's best to have buff aligned on a 32-bit boundary
28 */
29 static inline __wsum
csum_partial(const void * buff,int len,__wsum sum)30 csum_partial(const void *buff, int len, __wsum sum)
31 {
32 register unsigned long reg2 asm("2") = (unsigned long) buff;
33 register unsigned long reg3 asm("3") = (unsigned long) len;
34
35 asm volatile(
36 "0: cksm %0,%1\n" /* do checksum on longs */
37 " jo 0b\n"
38 : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
39 return sum;
40 }
41
42 /*
43 * the same as csum_partial_copy, but copies from user space.
44 *
45 * here even more important to align src and dst on a 32-bit (or even
46 * better 64-bit) boundary
47 *
48 * Copy from userspace and compute checksum.
49 */
50 static inline __wsum
csum_partial_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)51 csum_partial_copy_from_user(const void __user *src, void *dst,
52 int len, __wsum sum,
53 int *err_ptr)
54 {
55 if (unlikely(copy_from_user(dst, src, len)))
56 *err_ptr = -EFAULT;
57 return csum_partial(dst, len, sum);
58 }
59
60
61 static inline __wsum
csum_partial_copy_nocheck(const void * src,void * dst,int len,__wsum sum)62 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
63 {
64 memcpy(dst,src,len);
65 return csum_partial(dst, len, sum);
66 }
67
68 /*
69 * Fold a partial checksum without adding pseudo headers
70 */
csum_fold(__wsum sum)71 static inline __sum16 csum_fold(__wsum sum)
72 {
73 u32 csum = (__force u32) sum;
74
75 csum += (csum >> 16) + (csum << 16);
76 csum >>= 16;
77 return (__force __sum16) ~csum;
78 }
79
80 /*
81 * This is a version of ip_compute_csum() optimized for IP headers,
82 * which always checksum on 4 octet boundaries.
83 *
84 */
ip_fast_csum(const void * iph,unsigned int ihl)85 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
86 {
87 return csum_fold(csum_partial(iph, ihl*4, 0));
88 }
89
90 /*
91 * computes the checksum of the TCP/UDP pseudo-header
92 * returns a 32-bit checksum
93 */
94 static inline __wsum
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)95 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 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
120 static inline __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)121 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto,
122 __wsum sum)
123 {
124 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
125 }
126
127 /*
128 * this routine is used for miscellaneous IP-like checksums, mainly
129 * in icmp.c
130 */
131
ip_compute_csum(const void * buff,int len)132 static inline __sum16 ip_compute_csum(const void *buff, int len)
133 {
134 return csum_fold(csum_partial(buff, len, 0));
135 }
136
137 #endif /* _S390_CHECKSUM_H */
138
139
140