arch/um/include/sysdep-i386/checksum.h

   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 unsigned int csum_partial(const unsigned char * buff, int len,
  24                           unsigned int sum);
  25
  26 /*
  27  *      Note: when you get a NULL pointer exception here this means someone
  28  *      passed in an incorrect kernel address to one of these functions.
  29  *
  30  *      If you use these functions directly please don't forget the
  31  *      access_ok().
  32  */
  33
  34 static __inline__
  35 unsigned int csum_partial_copy_nocheck(const unsigned char *src, unsigned char *dst,
  36                                        int len, int sum)
  37 {
  38         memcpy(dst, src, len);
  39         return csum_partial(dst, len, sum);
  40 }
  41
  42 /*
  43  * the same as csum_partial, but copies from src while it
  44  * checksums, and handles user-space pointer exceptions correctly, when needed.
  45  *
  46  * here even more important to align src and dst on a 32-bit (or even
  47  * better 64-bit) boundary
  48  */
  49
  50 static __inline__
  51 unsigned int csum_partial_copy_from_user(const unsigned char __user *src,
  52                                          unsigned char *dst,
  53                                          int len, int sum, int *err_ptr)
  54 {
  55         if(copy_from_user(dst, src, len)){
  56                 *err_ptr = -EFAULT;
  57                 return(-1);
  58         }
  59
  60         return csum_partial(dst, len, sum);
  61 }
  62
  63 /*
  64  * These are the old (and unsafe) way of doing checksums, a warning message
  65  * will be printed if they are used and an exception occurs.
  66  *
  67  * these functions should go away after some time.
  68  */
  69
  70 #define csum_partial_copy_fromuser csum_partial_copy_from_user
  71
  72 /*
  73  *      This is a version of ip_compute_csum() optimized for IP headers,
  74  *      which always checksum on 4 octet boundaries.
  75  *
  76  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  77  *      Arnt Gulbrandsen.
  78  */
  79 static inline unsigned short ip_fast_csum(unsigned char * iph,
  80                                           unsigned int ihl)
  81 {
  82         unsigned int sum;
  83
  84         __asm__ __volatile__(
  85             "movl (%1), %0      ;\n"
  86             "subl $4, %2        ;\n"
  87             "jbe 2f             ;\n"
  88             "addl 4(%1), %0     ;\n"
  89             "adcl 8(%1), %0     ;\n"
  90             "adcl 12(%1), %0    ;\n"
  91 "1:         adcl 16(%1), %0     ;\n"
  92             "lea 4(%1), %1      ;\n"
  93             "decl %2            ;\n"
  94             "jne 1b             ;\n"
  95             "adcl $0, %0        ;\n"
  96             "movl %0, %2        ;\n"
  97             "shrl $16, %0       ;\n"
  98             "addw %w2, %w0      ;\n"
  99             "adcl $0, %0        ;\n"
 100             "notl %0            ;\n"
 101 "2:                             ;\n"
 102         /* Since the input registers which are loaded with iph and ipl
 103            are modified, we must also specify them as outputs, or gcc
 104            will assume they contain their original values. */
 105         : "=r" (sum), "=r" (iph), "=r" (ihl)
 106         : "1" (iph), "2" (ihl)
 107         : "memory");
 108         return sum;
 109 }
 110
 111 /*
 112  *      Fold a partial checksum
 113  */
 114
 115 static inline unsigned int csum_fold(unsigned int sum)
 116 {
 117         __asm__(
 118                 "addl %1, %0            ;\n"
 119                 "adcl $0xffff, %0       ;\n"
 120                 : "=r" (sum)
 121                 : "r" (sum << 16), "0" (sum & 0xffff0000)
 122         );
 123         return (~sum) >> 16;
 124 }
 125
 126 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 127                                                    unsigned long daddr,
 128                                                    unsigned short len,
 129                                                    unsigned short proto,
 130                                                    unsigned int sum)
 131 {
 132     __asm__(
 133         "addl %1, %0    ;\n"
 134         "adcl %2, %0    ;\n"
 135         "adcl %3, %0    ;\n"
 136         "adcl $0, %0    ;\n"
 137         : "=r" (sum)
 138         : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));
 139     return sum;
 140 }
 141
 142 /*
 143  * computes the checksum of the TCP/UDP pseudo-header
 144  * returns a 16-bit checksum, already complemented
 145  */
 146 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
 147                                                    unsigned long daddr,
 148                                                    unsigned short len,
 149                                                    unsigned short proto,
 150                                                    unsigned int sum)
 151 {
 152         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 153 }
 154
 155 /*
 156  * this routine is used for miscellaneous IP-like checksums, mainly
 157  * in icmp.c
 158  */
 159
 160 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
 161 {
 162     return csum_fold (csum_partial(buff, len, 0));
 163 }
 164
 165 #define _HAVE_ARCH_IPV6_CSUM
 166 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
 167                                                      struct in6_addr *daddr,
 168                                                      __u32 len,
 169                                                      unsigned short proto,
 170                                                      unsigned int sum)
 171 {
 172         __asm__(
 173                 "addl 0(%1), %0         ;\n"
 174                 "adcl 4(%1), %0         ;\n"
 175                 "adcl 8(%1), %0         ;\n"
 176                 "adcl 12(%1), %0        ;\n"
 177                 "adcl 0(%2), %0         ;\n"
 178                 "adcl 4(%2), %0         ;\n"
 179                 "adcl 8(%2), %0         ;\n"
 180                 "adcl 12(%2), %0        ;\n"
 181                 "adcl %3, %0            ;\n"
 182                 "adcl %4, %0            ;\n"
 183                 "adcl $0, %0            ;\n"
 184                 : "=&r" (sum)
 185                 : "r" (saddr), "r" (daddr),
 186                   "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
 187
 188         return csum_fold(sum);
 189 }
 190
 191 /*
 192  *      Copy and checksum to user
 193  */
 194 #define HAVE_CSUM_COPY_USER
 195 static __inline__ unsigned int csum_and_copy_to_user(const unsigned char *src,
 196                                                      unsigned char __user *dst,
 197                                                      int len, int sum, int *err_ptr)
 198 {
 199         if (access_ok(VERIFY_WRITE, dst, len)){
 200                 if(copy_to_user(dst, src, len)){
 201                         *err_ptr = -EFAULT;
 202                         return(-1);
 203                 }
 204
 205                 return csum_partial(src, len, sum);
 206         }
 207
 208         if (len)
 209                 *err_ptr = -EFAULT;
 210
 211         return -1; /* invalid checksum */
 212 }
 213
 214 #endif
 215
 216 /*
 217  * Overrides for Emacs so that we follow Linus's tabbing style.
 218  * Emacs will notice this stuff at the end of the file and automatically
 219  * adjust the settings for this buffer only.  This must remain at the end
 220  * of the file.
 221  * ---------------------------------------------------------------------------
 222  * Local variables:
 223  * c-file-style: "linux"
 224  * End:
 225  */