1 /* 2 * Licensed under the GPL 3 */ 4 5 #ifndef __UM_SYSDEP_CHECKSUM_H 6 #define __UM_SYSDEP_CHECKSUM_H 7 8 #include "linux/in6.h" 9 #include "linux/string.h" 10 11 /* 12 * computes the checksum of a memory block at buff, length len, 13 * and adds in "sum" (32-bit) 14 * 15 * returns a 32-bit number suitable for feeding into itself 16 * or csum_tcpudp_magic 17 * 18 * this function must be called with even lengths, except 19 * for the last fragment, which may be odd 20 * 21 * it's best to have buff aligned on a 32-bit boundary 22 */ 23 __wsum csum_partial(const void *buff, int len, __wsum sum); 24 25 /* 26 * Note: when you get a NULL pointer exception here this means someone 27 * passed in an incorrect kernel address to one of these functions. 28 * 29 * If you use these functions directly please don't forget the 30 * access_ok(). 31 */ 32 33 static __inline__ 34 __wsum csum_partial_copy_nocheck(const void *src, void *dst, 35 int len, __wsum sum) 36 { 37 memcpy(dst, src, len); 38 return csum_partial(dst, len, sum); 39 } 40 41 /* 42 * the same as csum_partial, but copies from src while it 43 * checksums, and handles user-space pointer exceptions correctly, when needed. 44 * 45 * here even more important to align src and dst on a 32-bit (or even 46 * better 64-bit) boundary 47 */ 48 49 static __inline__ 50 __wsum csum_partial_copy_from_user(const void __user *src, void *dst, 51 int len, __wsum sum, int *err_ptr) 52 { 53 if (copy_from_user(dst, src, len)) { 54 *err_ptr = -EFAULT; 55 return (__force __wsum)-1; 56 } 57 58 return csum_partial(dst, len, sum); 59 } 60 61 /* 62 * This is a version of ip_compute_csum() optimized for IP headers, 63 * which always checksum on 4 octet boundaries. 64 * 65 * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by 66 * Arnt Gulbrandsen. 67 */ 68 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 69 { 70 unsigned int sum; 71 72 __asm__ __volatile__( 73 "movl (%1), %0 ;\n" 74 "subl $4, %2 ;\n" 75 "jbe 2f ;\n" 76 "addl 4(%1), %0 ;\n" 77 "adcl 8(%1), %0 ;\n" 78 "adcl 12(%1), %0 ;\n" 79 "1: adcl 16(%1), %0 ;\n" 80 "lea 4(%1), %1 ;\n" 81 "decl %2 ;\n" 82 "jne 1b ;\n" 83 "adcl $0, %0 ;\n" 84 "movl %0, %2 ;\n" 85 "shrl $16, %0 ;\n" 86 "addw %w2, %w0 ;\n" 87 "adcl $0, %0 ;\n" 88 "notl %0 ;\n" 89 "2: ;\n" 90 /* Since the input registers which are loaded with iph and ipl 91 are modified, we must also specify them as outputs, or gcc 92 will assume they contain their original values. */ 93 : "=r" (sum), "=r" (iph), "=r" (ihl) 94 : "1" (iph), "2" (ihl) 95 : "memory"); 96 return (__force __sum16)sum; 97 } 98 99 /* 100 * Fold a partial checksum 101 */ 102 103 static inline __sum16 csum_fold(__wsum sum) 104 { 105 __asm__( 106 "addl %1, %0 ;\n" 107 "adcl $0xffff, %0 ;\n" 108 : "=r" (sum) 109 : "r" ((__force u32)sum << 16), 110 "0" ((__force u32)sum & 0xffff0000) 111 ); 112 return (__force __sum16)(~(__force u32)sum >> 16); 113 } 114 115 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, 116 unsigned short len, 117 unsigned short proto, 118 __wsum sum) 119 { 120 __asm__( 121 "addl %1, %0 ;\n" 122 "adcl %2, %0 ;\n" 123 "adcl %3, %0 ;\n" 124 "adcl $0, %0 ;\n" 125 : "=r" (sum) 126 : "g" (daddr), "g"(saddr), "g"((len + proto) << 8), "0"(sum)); 127 return sum; 128 } 129 130 /* 131 * computes the checksum of the TCP/UDP pseudo-header 132 * returns a 16-bit checksum, already complemented 133 */ 134 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, 135 unsigned short len, 136 unsigned short proto, 137 __wsum sum) 138 { 139 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 140 } 141 142 /* 143 * this routine is used for miscellaneous IP-like checksums, mainly 144 * in icmp.c 145 */ 146 147 static inline __sum16 ip_compute_csum(const void *buff, int len) 148 { 149 return csum_fold (csum_partial(buff, len, 0)); 150 } 151 152 #define _HAVE_ARCH_IPV6_CSUM 153 static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, 154 const struct in6_addr *daddr, 155 __u32 len, unsigned short proto, 156 __wsum sum) 157 { 158 __asm__( 159 "addl 0(%1), %0 ;\n" 160 "adcl 4(%1), %0 ;\n" 161 "adcl 8(%1), %0 ;\n" 162 "adcl 12(%1), %0 ;\n" 163 "adcl 0(%2), %0 ;\n" 164 "adcl 4(%2), %0 ;\n" 165 "adcl 8(%2), %0 ;\n" 166 "adcl 12(%2), %0 ;\n" 167 "adcl %3, %0 ;\n" 168 "adcl %4, %0 ;\n" 169 "adcl $0, %0 ;\n" 170 : "=&r" (sum) 171 : "r" (saddr), "r" (daddr), 172 "r"(htonl(len)), "r"(htonl(proto)), "0"(sum)); 173 174 return csum_fold(sum); 175 } 176 177 /* 178 * Copy and checksum to user 179 */ 180 #define HAVE_CSUM_COPY_USER 181 static __inline__ __wsum csum_and_copy_to_user(const void *src, 182 void __user *dst, 183 int len, __wsum sum, int *err_ptr) 184 { 185 if (access_ok(VERIFY_WRITE, dst, len)) { 186 if (copy_to_user(dst, src, len)) { 187 *err_ptr = -EFAULT; 188 return (__force __wsum)-1; 189 } 190 191 return csum_partial(src, len, sum); 192 } 193 194 if (len) 195 *err_ptr = -EFAULT; 196 197 return (__force __wsum)-1; /* invalid checksum */ 198 } 199 200 #endif 201 202