1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * arch/alpha/lib/checksum.c 4 * 5 * This file contains network checksum routines that are better done 6 * in an architecture-specific manner due to speed.. 7 * Comments in other versions indicate that the algorithms are from RFC1071 8 * 9 * accelerated versions (and 21264 assembly versions ) contributed by 10 * Rick Gorton <rick.gorton@alpha-processor.com> 11 */ 12 13 #include <linux/module.h> 14 #include <linux/string.h> 15 #include <net/checksum.h> 16 17 #include <asm/byteorder.h> 18 #include <asm/checksum.h> 19 20 static inline unsigned short from64to16(unsigned long x) 21 { 22 /* Using extract instructions is a bit more efficient 23 than the original shift/bitmask version. */ 24 25 union { 26 unsigned long ul; 27 unsigned int ui[2]; 28 unsigned short us[4]; 29 } in_v, tmp_v, out_v; 30 31 in_v.ul = x; 32 tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1]; 33 34 /* Since the bits of tmp_v.sh[3] are going to always be zero, 35 we don't have to bother to add that in. */ 36 out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1] 37 + (unsigned long) tmp_v.us[2]; 38 39 /* Similarly, out_v.us[2] is always zero for the final add. */ 40 return out_v.us[0] + out_v.us[1]; 41 } 42 43 /* 44 * computes the checksum of the TCP/UDP pseudo-header 45 * returns a 16-bit checksum, already complemented. 46 */ 47 __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, 48 __u32 len, __u8 proto, __wsum sum) 49 { 50 return (__force __sum16)~from64to16( 51 (__force u64)saddr + (__force u64)daddr + 52 (__force u64)sum + ((len + proto) << 8)); 53 } 54 EXPORT_SYMBOL(csum_tcpudp_magic); 55 56 __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, 57 __u32 len, __u8 proto, __wsum sum) 58 { 59 unsigned long result; 60 61 result = (__force u64)saddr + (__force u64)daddr + 62 (__force u64)sum + ((len + proto) << 8); 63 64 /* Fold down to 32-bits so we don't lose in the typedef-less 65 network stack. */ 66 /* 64 to 33 */ 67 result = (result & 0xffffffff) + (result >> 32); 68 /* 33 to 32 */ 69 result = (result & 0xffffffff) + (result >> 32); 70 return (__force __wsum)result; 71 } 72 EXPORT_SYMBOL(csum_tcpudp_nofold); 73 74 /* 75 * Do a 64-bit checksum on an arbitrary memory area.. 76 * 77 * This isn't a great routine, but it's not _horrible_ either. The 78 * inner loop could be unrolled a bit further, and there are better 79 * ways to do the carry, but this is reasonable. 80 */ 81 static inline unsigned long do_csum(const unsigned char * buff, int len) 82 { 83 int odd, count; 84 unsigned long result = 0; 85 86 if (len <= 0) 87 goto out; 88 odd = 1 & (unsigned long) buff; 89 if (odd) { 90 result = *buff << 8; 91 len--; 92 buff++; 93 } 94 count = len >> 1; /* nr of 16-bit words.. */ 95 if (count) { 96 if (2 & (unsigned long) buff) { 97 result += *(unsigned short *) buff; 98 count--; 99 len -= 2; 100 buff += 2; 101 } 102 count >>= 1; /* nr of 32-bit words.. */ 103 if (count) { 104 if (4 & (unsigned long) buff) { 105 result += *(unsigned int *) buff; 106 count--; 107 len -= 4; 108 buff += 4; 109 } 110 count >>= 1; /* nr of 64-bit words.. */ 111 if (count) { 112 unsigned long carry = 0; 113 do { 114 unsigned long w = *(unsigned long *) buff; 115 count--; 116 buff += 8; 117 result += carry; 118 result += w; 119 carry = (w > result); 120 } while (count); 121 result += carry; 122 result = (result & 0xffffffff) + (result >> 32); 123 } 124 if (len & 4) { 125 result += *(unsigned int *) buff; 126 buff += 4; 127 } 128 } 129 if (len & 2) { 130 result += *(unsigned short *) buff; 131 buff += 2; 132 } 133 } 134 if (len & 1) 135 result += *buff; 136 result = from64to16(result); 137 if (odd) 138 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); 139 out: 140 return result; 141 } 142 143 /* 144 * This is a version of ip_compute_csum() optimized for IP headers, 145 * which always checksum on 4 octet boundaries. 146 */ 147 __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 148 { 149 return (__force __sum16)~do_csum(iph,ihl*4); 150 } 151 EXPORT_SYMBOL(ip_fast_csum); 152 153 /* 154 * computes the checksum of a memory block at buff, length len, 155 * and adds in "sum" (32-bit) 156 * 157 * returns a 32-bit number suitable for feeding into itself 158 * or csum_tcpudp_magic 159 * 160 * this function must be called with even lengths, except 161 * for the last fragment, which may be odd 162 * 163 * it's best to have buff aligned on a 32-bit boundary 164 */ 165 __wsum csum_partial(const void *buff, int len, __wsum sum) 166 { 167 unsigned long result = do_csum(buff, len); 168 169 /* add in old sum, and carry.. */ 170 result += (__force u32)sum; 171 /* 32+c bits -> 32 bits */ 172 result = (result & 0xffffffff) + (result >> 32); 173 return (__force __wsum)result; 174 } 175 176 EXPORT_SYMBOL(csum_partial); 177 178 /* 179 * this routine is used for miscellaneous IP-like checksums, mainly 180 * in icmp.c 181 */ 182 __sum16 ip_compute_csum(const void *buff, int len) 183 { 184 return (__force __sum16)~from64to16(do_csum(buff,len)); 185 } 186 EXPORT_SYMBOL(ip_compute_csum); 187