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 #ifdef CONFIG_GENERIC_CSUM 16 17 #include <asm-generic/checksum.h> 18 19 #else /* CONFIG_GENERIC_CSUM */ 20 21 #include <linux/uaccess.h> 22 #include <linux/in6.h> 23 24 /* 25 * Computes the checksum of a memory block at buff, length len, 26 * and adds in "sum" (32-bit). 27 * 28 * Returns a 32-bit number suitable for feeding into itself 29 * or csum_tcpudp_magic. 30 * 31 * This function must be called with even lengths, except 32 * for the last fragment, which may be odd. 33 * 34 * It's best to have buff aligned on a 32-bit boundary. 35 */ 36 static inline __wsum csum_partial(const void *buff, int len, __wsum sum) 37 { 38 union register_pair rp = { 39 .even = (unsigned long) buff, 40 .odd = (unsigned long) len, 41 }; 42 43 asm volatile( 44 "0: cksm %[sum],%[rp]\n" 45 " jo 0b\n" 46 : [sum] "+&d" (sum), [rp] "+&d" (rp.pair) : : "cc", "memory"); 47 return sum; 48 } 49 50 /* 51 * Fold a partial checksum without adding pseudo headers. 52 */ 53 static inline __sum16 csum_fold(__wsum sum) 54 { 55 u32 csum = (__force u32) sum; 56 57 csum += (csum >> 16) | (csum << 16); 58 csum >>= 16; 59 return (__force __sum16) ~csum; 60 } 61 62 /* 63 * This is a version of ip_compute_csum() optimized for IP headers, 64 * which always checksums on 4 octet boundaries. 65 */ 66 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 67 { 68 __u64 csum = 0; 69 __u32 *ptr = (u32 *)iph; 70 71 csum += *ptr++; 72 csum += *ptr++; 73 csum += *ptr++; 74 csum += *ptr++; 75 ihl -= 4; 76 while (ihl--) 77 csum += *ptr++; 78 csum += (csum >> 32) | (csum << 32); 79 return csum_fold((__force __wsum)(csum >> 32)); 80 } 81 82 /* 83 * Computes the checksum of the TCP/UDP pseudo-header. 84 * Returns a 32-bit checksum. 85 */ 86 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, 87 __u8 proto, __wsum sum) 88 { 89 __u64 csum = (__force __u64)sum; 90 91 csum += (__force __u32)saddr; 92 csum += (__force __u32)daddr; 93 csum += len; 94 csum += proto; 95 csum += (csum >> 32) | (csum << 32); 96 return (__force __wsum)(csum >> 32); 97 } 98 99 /* 100 * Computes the checksum of the TCP/UDP pseudo-header. 101 * Returns a 16-bit checksum, already complemented. 102 */ 103 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, 104 __u8 proto, __wsum sum) 105 { 106 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum)); 107 } 108 109 /* 110 * Used for miscellaneous IP-like checksums, mainly icmp. 111 */ 112 static inline __sum16 ip_compute_csum(const void *buff, int len) 113 { 114 return csum_fold(csum_partial(buff, len, 0)); 115 } 116 117 #define _HAVE_ARCH_IPV6_CSUM 118 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr, 119 const struct in6_addr *daddr, 120 __u32 len, __u8 proto, __wsum csum) 121 { 122 __u64 sum = (__force __u64)csum; 123 124 sum += (__force __u32)saddr->s6_addr32[0]; 125 sum += (__force __u32)saddr->s6_addr32[1]; 126 sum += (__force __u32)saddr->s6_addr32[2]; 127 sum += (__force __u32)saddr->s6_addr32[3]; 128 sum += (__force __u32)daddr->s6_addr32[0]; 129 sum += (__force __u32)daddr->s6_addr32[1]; 130 sum += (__force __u32)daddr->s6_addr32[2]; 131 sum += (__force __u32)daddr->s6_addr32[3]; 132 sum += len; 133 sum += proto; 134 sum += (sum >> 32) | (sum << 32); 135 return csum_fold((__force __wsum)(sum >> 32)); 136 } 137 138 #endif /* CONFIG_GENERIC_CSUM */ 139 #endif /* _S390_CHECKSUM_H */ 140