1/* 2 * S390 fast network checksum routines 3 * 4 * S390 version 5 * Copyright IBM Corp. 1999 6 * Author(s): Ulrich Hild (first version) 7 * Martin Schwidefsky (heavily optimized CKSM version) 8 * D.J. Barrow (third attempt) 9 */ 10 11#ifndef _S390_CHECKSUM_H 12#define _S390_CHECKSUM_H 13 14#include <asm/uaccess.h> 15 16/* 17 * computes the checksum of a memory block at buff, length len, 18 * and adds in "sum" (32-bit) 19 * 20 * returns a 32-bit number suitable for feeding into itself 21 * or csum_tcpudp_magic 22 * 23 * this function must be called with even lengths, except 24 * for the last fragment, which may be odd 25 * 26 * it's best to have buff aligned on a 32-bit boundary 27 */ 28static inline __wsum 29csum_partial(const void *buff, int len, __wsum sum) 30{ 31 register unsigned long reg2 asm("2") = (unsigned long) buff; 32 register unsigned long reg3 asm("3") = (unsigned long) len; 33 34 asm volatile( 35 "0: cksm %0,%1\n" /* do checksum on longs */ 36 " jo 0b\n" 37 : "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory"); 38 return sum; 39} 40 41/* 42 * the same as csum_partial_copy, but copies from user space. 43 * 44 * here even more important to align src and dst on a 32-bit (or even 45 * better 64-bit) boundary 46 * 47 * Copy from userspace and compute checksum. 48 */ 49static inline __wsum 50csum_partial_copy_from_user(const void __user *src, void *dst, 51 int len, __wsum sum, 52 int *err_ptr) 53{ 54 if (unlikely(copy_from_user(dst, src, len))) 55 *err_ptr = -EFAULT; 56 return csum_partial(dst, len, sum); 57} 58 59 60static inline __wsum 61csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum) 62{ 63 memcpy(dst,src,len); 64 return csum_partial(dst, len, sum); 65} 66 67/* 68 * Fold a partial checksum without adding pseudo headers 69 */ 70static inline __sum16 csum_fold(__wsum sum) 71{ 72 u32 csum = (__force u32) sum; 73 74 csum += (csum >> 16) + (csum << 16); 75 csum >>= 16; 76 return (__force __sum16) ~csum; 77} 78 79/* 80 * This is a version of ip_compute_csum() optimized for IP headers, 81 * which always checksum on 4 octet boundaries. 82 * 83 */ 84static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 85{ 86 return csum_fold(csum_partial(iph, ihl*4, 0)); 87} 88 89/* 90 * computes the checksum of the TCP/UDP pseudo-header 91 * returns a 32-bit checksum 92 */ 93static inline __wsum 94csum_tcpudp_nofold(__be32 saddr, __be32 daddr, 95 unsigned short len, unsigned short proto, 96 __wsum sum) 97{ 98 __u32 csum = (__force __u32)sum; 99 100 csum += (__force __u32)saddr; 101 if (csum < (__force __u32)saddr) 102 csum++; 103 104 csum += (__force __u32)daddr; 105 if (csum < (__force __u32)daddr) 106 csum++; 107 108 csum += len + proto; 109 if (csum < len + proto) 110 csum++; 111 112 return (__force __wsum)csum; 113} 114 115/* 116 * computes the checksum of the TCP/UDP pseudo-header 117 * returns a 16-bit checksum, already complemented 118 */ 119 120static inline __sum16 121csum_tcpudp_magic(__be32 saddr, __be32 daddr, 122 unsigned short len, unsigned short proto, 123 __wsum sum) 124{ 125 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 126} 127 128/* 129 * this routine is used for miscellaneous IP-like checksums, mainly 130 * in icmp.c 131 */ 132 133static inline __sum16 ip_compute_csum(const void *buff, int len) 134{ 135 return csum_fold(csum_partial(buff, len, 0)); 136} 137 138#endif /* _S390_CHECKSUM_H */ 139 140 141