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 */ 28 static inline __wsum 29 csum_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 */ 49 static inline __wsum 50 csum_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 60 static inline __wsum 61 csum_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 */ 70 static 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 */ 84 static 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 */ 93 static inline __wsum 94 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, 95 __wsum sum) 96 { 97 __u32 csum = (__force __u32)sum; 98 99 csum += (__force __u32)saddr; 100 if (csum < (__force __u32)saddr) 101 csum++; 102 103 csum += (__force __u32)daddr; 104 if (csum < (__force __u32)daddr) 105 csum++; 106 107 csum += len + proto; 108 if (csum < len + proto) 109 csum++; 110 111 return (__force __wsum)csum; 112 } 113 114 /* 115 * computes the checksum of the TCP/UDP pseudo-header 116 * returns a 16-bit checksum, already complemented 117 */ 118 119 static inline __sum16 120 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, 121 __wsum sum) 122 { 123 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 124 } 125 126 /* 127 * this routine is used for miscellaneous IP-like checksums, mainly 128 * in icmp.c 129 */ 130 131 static inline __sum16 ip_compute_csum(const void *buff, int len) 132 { 133 return csum_fold(csum_partial(buff, len, 0)); 134 } 135 136 #endif /* _S390_CHECKSUM_H */ 137 138 139