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 /* 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 checksum on 4 octet boundaries. 57 * 58 */ 59 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 60 { 61 return csum_fold(csum_partial(iph, ihl*4, 0)); 62 } 63 64 /* 65 * computes the checksum of the TCP/UDP pseudo-header 66 * returns a 32-bit checksum 67 */ 68 static inline __wsum 69 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, 70 __wsum sum) 71 { 72 __u32 csum = (__force __u32)sum; 73 74 csum += (__force __u32)saddr; 75 if (csum < (__force __u32)saddr) 76 csum++; 77 78 csum += (__force __u32)daddr; 79 if (csum < (__force __u32)daddr) 80 csum++; 81 82 csum += len + proto; 83 if (csum < len + proto) 84 csum++; 85 86 return (__force __wsum)csum; 87 } 88 89 /* 90 * computes the checksum of the TCP/UDP pseudo-header 91 * returns a 16-bit checksum, already complemented 92 */ 93 94 static inline __sum16 95 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, 96 __wsum sum) 97 { 98 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 99 } 100 101 /* 102 * this routine is used for miscellaneous IP-like checksums, mainly 103 * in icmp.c 104 */ 105 106 static inline __sum16 ip_compute_csum(const void *buff, int len) 107 { 108 return csum_fold(csum_partial(buff, len, 0)); 109 } 110 111 #endif /* _S390_CHECKSUM_H */ 112 113 114