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 *src, unsigned char *dst,
  52                                          int len, int sum, int *err_ptr)
  53 {
  54         if(copy_from_user(dst, src, len)){
  55                 *err_ptr = -EFAULT;
  56                 return(-1);
  57         }
  58
  59         return csum_partial(dst, len, sum);
  60 }
  61
  62 /*
  63  * These are the old (and unsafe) way of doing checksums, a warning message
  64  * will be printed if they are used and an exception occurs.
  65  *
  66  * these functions should go away after some time.
  67  */
  68
  69 #define csum_partial_copy_fromuser csum_partial_copy_from_user
  70
  71 /*
  72  *      This is a version of ip_compute_csum() optimized for IP headers,
  73  *      which always checksum on 4 octet boundaries.
  74  *
  75  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  76  *      Arnt Gulbrandsen.
  77  */
  78 static inline unsigned short ip_fast_csum(unsigned char * iph,
  79                                           unsigned int ihl)
  80 {
  81         unsigned int sum;
  82
  83         __asm__ __volatile__(
  84             "movl (%1), %0      ;\n"
  85             "subl $4, %2        ;\n"
  86             "jbe 2f             ;\n"
  87             "addl 4(%1), %0     ;\n"
  88             "adcl 8(%1), %0     ;\n"
  89             "adcl 12(%1), %0    ;\n"
  90 "1:         adcl 16(%1), %0     ;\n"
  91             "lea 4(%1), %1      ;\n"
  92             "decl %2            ;\n"
  93             "jne 1b             ;\n"
  94             "adcl $0, %0        ;\n"
  95             "movl %0, %2        ;\n"
  96             "shrl $16, %0       ;\n"
  97             "addw %w2, %w0      ;\n"
  98             "adcl $0, %0        ;\n"
  99             "notl %0            ;\n"
 100 "2:                             ;\n"
 101         /* Since the input registers which are loaded with iph and ipl
 102            are modified, we must also specify them as outputs, or gcc
 103            will assume they contain their original values. */
 104         : "=r" (sum), "=r" (iph), "=r" (ihl)
 105         : "1" (iph), "2" (ihl)
 106         : "memory");
 107         return(sum);
 108 }
 109
 110 /*
 111  *      Fold a partial checksum
 112  */
 113
 114 static inline unsigned int csum_fold(unsigned int sum)
 115 {
 116         __asm__(
 117                 "addl %1, %0            ;\n"
 118                 "adcl $0xffff, %0       ;\n"
 119                 : "=r" (sum)
 120                 : "r" (sum << 16), "0" (sum & 0xffff0000)
 121         );
 122         return (~sum) >> 16;
 123 }
 124
 125 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 126                                                    unsigned long daddr,
 127                                                    unsigned short len,
 128                                                    unsigned short proto,
 129                                                    unsigned int sum)
 130 {
 131     __asm__(
 132         "addl %1, %0    ;\n"
 133         "adcl %2, %0    ;\n"
 134         "adcl %3, %0    ;\n"
 135         "adcl $0, %0    ;\n"
 136         : "=r" (sum)
 137         : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));
 138     return sum;
 139 }
 140
 141 /*
 142  * computes the checksum of the TCP/UDP pseudo-header
 143  * returns a 16-bit checksum, already complemented
 144  */
 145 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
 146                                                    unsigned long daddr,
 147                                                    unsigned short len,
 148                                                    unsigned short proto,
 149                                                    unsigned int sum)
 150 {
 151         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 152 }
 153
 154 /*
 155  * this routine is used for miscellaneous IP-like checksums, mainly
 156  * in icmp.c
 157  */
 158
 159 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
 160 {
 161     return csum_fold (csum_partial(buff, len, 0));
 162 }
 163
 164 #define _HAVE_ARCH_IPV6_CSUM
 165 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
 166                                                      struct in6_addr *daddr,
 167                                                      __u32 len,
 168                                                      unsigned short proto,
 169                                                      unsigned int sum)
 170 {
 171         __asm__(
 172                 "addl 0(%1), %0         ;\n"
 173                 "adcl 4(%1), %0         ;\n"
 174                 "adcl 8(%1), %0         ;\n"
 175                 "adcl 12(%1), %0        ;\n"
 176                 "adcl 0(%2), %0         ;\n"
 177                 "adcl 4(%2), %0         ;\n"
 178                 "adcl 8(%2), %0         ;\n"
 179                 "adcl 12(%2), %0        ;\n"
 180                 "adcl %3, %0            ;\n"
 181                 "adcl %4, %0            ;\n"
 182                 "adcl $0, %0            ;\n"
 183                 : "=&r" (sum)
 184                 : "r" (saddr), "r" (daddr),
 185                   "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
 186
 187         return csum_fold(sum);
 188 }
 189
 190 /*
 191  *      Copy and checksum to user
 192  */
 193 #define HAVE_CSUM_COPY_USER
 194 static __inline__ unsigned int csum_and_copy_to_user(const unsigned char *src,
 195                                                      unsigned char *dst,
 196                                                      int len, int sum, int *err_ptr)
 197 {
 198         if (access_ok(VERIFY_WRITE, dst, len)){
 199                 if(copy_to_user(dst, src, len)){
 200                         *err_ptr = -EFAULT;
 201                         return(-1);
 202                 }
 203
 204                 return csum_partial(src, len, sum);
 205         }
 206
 207         if (len)
 208                 *err_ptr = -EFAULT;
 209
 210         return -1; /* invalid checksum */
 211 }
 212
 213 #endif
 214
 215 /*
 216  * Overrides for Emacs so that we follow Linus's tabbing style.
 217  * Emacs will notice this stuff at the end of the file and automatically
 218  * adjust the settings for this buffer only.  This must remain at the end
 219  * of the file.
 220  * ---------------------------------------------------------------------------
 221  * Local variables:
 222  * c-file-style: "linux"
 223  * End:
 224  */