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. If we catch an exception 48 * then zero the rest of the buffer. 49 */ 50 static inline __wsum 51 csum_partial_copy_from_user(const void __user *src, void *dst, 52 int len, __wsum sum, 53 int *err_ptr) 54 { 55 int missing; 56 57 missing = copy_from_user(dst, src, len); 58 if (missing) { 59 memset(dst + len - missing, 0, missing); 60 *err_ptr = -EFAULT; 61 } 62 63 return csum_partial(dst, len, sum); 64 } 65 66 67 static inline __wsum 68 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum) 69 { 70 memcpy(dst,src,len); 71 return csum_partial(dst, len, sum); 72 } 73 74 /* 75 * Fold a partial checksum without adding pseudo headers 76 */ 77 static inline __sum16 csum_fold(__wsum sum) 78 { 79 u32 csum = (__force u32) sum; 80 81 csum += (csum >> 16) + (csum << 16); 82 csum >>= 16; 83 return (__force __sum16) ~csum; 84 } 85 86 /* 87 * This is a version of ip_compute_csum() optimized for IP headers, 88 * which always checksum on 4 octet boundaries. 89 * 90 */ 91 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 92 { 93 return csum_fold(csum_partial(iph, ihl*4, 0)); 94 } 95 96 /* 97 * computes the checksum of the TCP/UDP pseudo-header 98 * returns a 32-bit checksum 99 */ 100 static inline __wsum 101 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, 102 unsigned short len, unsigned short proto, 103 __wsum sum) 104 { 105 __u32 csum = (__force __u32)sum; 106 107 csum += (__force __u32)saddr; 108 if (csum < (__force __u32)saddr) 109 csum++; 110 111 csum += (__force __u32)daddr; 112 if (csum < (__force __u32)daddr) 113 csum++; 114 115 csum += len + proto; 116 if (csum < len + proto) 117 csum++; 118 119 return (__force __wsum)csum; 120 } 121 122 /* 123 * computes the checksum of the TCP/UDP pseudo-header 124 * returns a 16-bit checksum, already complemented 125 */ 126 127 static inline __sum16 128 csum_tcpudp_magic(__be32 saddr, __be32 daddr, 129 unsigned short len, unsigned short proto, 130 __wsum sum) 131 { 132 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 133 } 134 135 /* 136 * this routine is used for miscellaneous IP-like checksums, mainly 137 * in icmp.c 138 */ 139 140 static inline __sum16 ip_compute_csum(const void *buff, int len) 141 { 142 return csum_fold(csum_partial(buff, len, 0)); 143 } 144 145 #endif /* _S390_CHECKSUM_H */ 146 147 148