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