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 #include <linux/in6.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 */
csum_partial(const void * buff,int len,__wsum sum)30 static inline __wsum csum_partial(const void *buff, int len, __wsum sum)
31 {
32 union register_pair rp = {
33 .even = (unsigned long) buff,
34 .odd = (unsigned long) len,
35 };
36
37 asm volatile(
38 "0: cksm %[sum],%[rp]\n"
39 " jo 0b\n"
40 : [sum] "+&d" (sum), [rp] "+&d" (rp.pair) : : "cc", "memory");
41 return sum;
42 }
43
44 /*
45 * Fold a partial checksum without adding pseudo headers.
46 */
csum_fold(__wsum sum)47 static inline __sum16 csum_fold(__wsum sum)
48 {
49 u32 csum = (__force u32) sum;
50
51 csum += (csum >> 16) | (csum << 16);
52 csum >>= 16;
53 return (__force __sum16) ~csum;
54 }
55
56 /*
57 * This is a version of ip_compute_csum() optimized for IP headers,
58 * which always checksums on 4 octet boundaries.
59 */
ip_fast_csum(const void * iph,unsigned int ihl)60 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
61 {
62 __u64 csum = 0;
63 __u32 *ptr = (u32 *)iph;
64
65 csum += *ptr++;
66 csum += *ptr++;
67 csum += *ptr++;
68 csum += *ptr++;
69 ihl -= 4;
70 while (ihl--)
71 csum += *ptr++;
72 csum += (csum >> 32) | (csum << 32);
73 return csum_fold((__force __wsum)(csum >> 32));
74 }
75
76 /*
77 * Computes the checksum of the TCP/UDP pseudo-header.
78 * Returns a 32-bit checksum.
79 */
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)80 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
81 __u8 proto, __wsum sum)
82 {
83 __u64 csum = (__force __u64)sum;
84
85 csum += (__force __u32)saddr;
86 csum += (__force __u32)daddr;
87 csum += len;
88 csum += proto;
89 csum += (csum >> 32) | (csum << 32);
90 return (__force __wsum)(csum >> 32);
91 }
92
93 /*
94 * Computes the checksum of the TCP/UDP pseudo-header.
95 * Returns a 16-bit checksum, already complemented.
96 */
csum_tcpudp_magic(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)97 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
98 __u8 proto, __wsum sum)
99 {
100 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
101 }
102
103 /*
104 * Used for miscellaneous IP-like checksums, mainly icmp.
105 */
ip_compute_csum(const void * buff,int len)106 static inline __sum16 ip_compute_csum(const void *buff, int len)
107 {
108 return csum_fold(csum_partial(buff, len, 0));
109 }
110
111 #define _HAVE_ARCH_IPV6_CSUM
csum_ipv6_magic(const struct in6_addr * saddr,const struct in6_addr * daddr,__u32 len,__u8 proto,__wsum csum)112 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
113 const struct in6_addr *daddr,
114 __u32 len, __u8 proto, __wsum csum)
115 {
116 __u64 sum = (__force __u64)csum;
117
118 sum += (__force __u32)saddr->s6_addr32[0];
119 sum += (__force __u32)saddr->s6_addr32[1];
120 sum += (__force __u32)saddr->s6_addr32[2];
121 sum += (__force __u32)saddr->s6_addr32[3];
122 sum += (__force __u32)daddr->s6_addr32[0];
123 sum += (__force __u32)daddr->s6_addr32[1];
124 sum += (__force __u32)daddr->s6_addr32[2];
125 sum += (__force __u32)daddr->s6_addr32[3];
126 sum += len;
127 sum += proto;
128 sum += (sum >> 32) | (sum << 32);
129 return csum_fold((__force __wsum)(sum >> 32));
130 }
131
132 #endif /* _S390_CHECKSUM_H */
133