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/kasan-checks.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 kasan_check_read(buff, len);
38 asm volatile(
39 "0: cksm %[sum],%[rp]\n"
40 " jo 0b\n"
41 : [sum] "+&d" (sum), [rp] "+&d" (rp.pair) : : "cc", "memory");
42 return sum;
43 }
44
45 /*
46 * Fold a partial checksum without adding pseudo headers.
47 */
csum_fold(__wsum sum)48 static inline __sum16 csum_fold(__wsum sum)
49 {
50 u32 csum = (__force u32) sum;
51
52 csum += (csum >> 16) | (csum << 16);
53 csum >>= 16;
54 return (__force __sum16) ~csum;
55 }
56
57 /*
58 * This is a version of ip_compute_csum() optimized for IP headers,
59 * which always checksums on 4 octet boundaries.
60 */
ip_fast_csum(const void * iph,unsigned int ihl)61 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
62 {
63 __u64 csum = 0;
64 __u32 *ptr = (u32 *)iph;
65
66 csum += *ptr++;
67 csum += *ptr++;
68 csum += *ptr++;
69 csum += *ptr++;
70 ihl -= 4;
71 while (ihl--)
72 csum += *ptr++;
73 csum += (csum >> 32) | (csum << 32);
74 return csum_fold((__force __wsum)(csum >> 32));
75 }
76
77 /*
78 * Computes the checksum of the TCP/UDP pseudo-header.
79 * Returns a 32-bit checksum.
80 */
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)81 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
82 __u8 proto, __wsum sum)
83 {
84 __u64 csum = (__force __u64)sum;
85
86 csum += (__force __u32)saddr;
87 csum += (__force __u32)daddr;
88 csum += len;
89 csum += proto;
90 csum += (csum >> 32) | (csum << 32);
91 return (__force __wsum)(csum >> 32);
92 }
93
94 /*
95 * Computes the checksum of the TCP/UDP pseudo-header.
96 * Returns a 16-bit checksum, already complemented.
97 */
csum_tcpudp_magic(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)98 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
99 __u8 proto, __wsum sum)
100 {
101 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
102 }
103
104 /*
105 * Used for miscellaneous IP-like checksums, mainly icmp.
106 */
ip_compute_csum(const void * buff,int len)107 static inline __sum16 ip_compute_csum(const void *buff, int len)
108 {
109 return csum_fold(csum_partial(buff, len, 0));
110 }
111
112 #define _HAVE_ARCH_IPV6_CSUM
csum_ipv6_magic(const struct in6_addr * saddr,const struct in6_addr * daddr,__u32 len,__u8 proto,__wsum csum)113 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
114 const struct in6_addr *daddr,
115 __u32 len, __u8 proto, __wsum csum)
116 {
117 __u64 sum = (__force __u64)csum;
118
119 sum += (__force __u32)saddr->s6_addr32[0];
120 sum += (__force __u32)saddr->s6_addr32[1];
121 sum += (__force __u32)saddr->s6_addr32[2];
122 sum += (__force __u32)saddr->s6_addr32[3];
123 sum += (__force __u32)daddr->s6_addr32[0];
124 sum += (__force __u32)daddr->s6_addr32[1];
125 sum += (__force __u32)daddr->s6_addr32[2];
126 sum += (__force __u32)daddr->s6_addr32[3];
127 sum += len;
128 sum += proto;
129 sum += (sum >> 32) | (sum << 32);
130 return csum_fold((__force __wsum)(sum >> 32));
131 }
132
133 #endif /* _S390_CHECKSUM_H */
134