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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 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