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 17 /* 18 * computes the checksum of a memory block at buff, length len, 19 * and adds in "sum" (32-bit) 20 * 21 * returns a 32-bit number suitable for feeding into itself 22 * or csum_tcpudp_magic 23 * 24 * this function must be called with even lengths, except 25 * for the last fragment, which may be odd 26 * 27 * it's best to have buff aligned on a 32-bit boundary 28 */ 29 static inline __wsum 30 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 static inline __wsum 43 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum) 44 { 45 memcpy(dst,src,len); 46 return csum_partial(dst, len, sum); 47 } 48 49 /* 50 * Fold a partial checksum without adding pseudo headers 51 */ 52 static inline __sum16 csum_fold(__wsum sum) 53 { 54 u32 csum = (__force u32) sum; 55 56 csum += (csum >> 16) + (csum << 16); 57 csum >>= 16; 58 return (__force __sum16) ~csum; 59 } 60 61 /* 62 * This is a version of ip_compute_csum() optimized for IP headers, 63 * which always checksum on 4 octet boundaries. 64 * 65 */ 66 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 67 { 68 return csum_fold(csum_partial(iph, ihl*4, 0)); 69 } 70 71 /* 72 * computes the checksum of the TCP/UDP pseudo-header 73 * returns a 32-bit checksum 74 */ 75 static inline __wsum 76 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, 77 __wsum sum) 78 { 79 __u32 csum = (__force __u32)sum; 80 81 csum += (__force __u32)saddr; 82 if (csum < (__force __u32)saddr) 83 csum++; 84 85 csum += (__force __u32)daddr; 86 if (csum < (__force __u32)daddr) 87 csum++; 88 89 csum += len + proto; 90 if (csum < len + proto) 91 csum++; 92 93 return (__force __wsum)csum; 94 } 95 96 /* 97 * computes the checksum of the TCP/UDP pseudo-header 98 * returns a 16-bit checksum, already complemented 99 */ 100 101 static inline __sum16 102 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, 103 __wsum sum) 104 { 105 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 106 } 107 108 /* 109 * this routine is used for miscellaneous IP-like checksums, mainly 110 * in icmp.c 111 */ 112 113 static inline __sum16 ip_compute_csum(const void *buff, int len) 114 { 115 return csum_fold(csum_partial(buff, len, 0)); 116 } 117 118 #endif /* _S390_CHECKSUM_H */ 119 120 121