include/asm-i386/checksum.h

   1 #ifndef _I386_CHECKSUM_H
   2 #define _I386_CHECKSUM_H
   3
   4
   5 /*
   6  * computes the checksum of a memory block at buff, length len,
   7  * and adds in "sum" (32-bit)
   8  *
   9  * returns a 32-bit number suitable for feeding into itself
  10  * or csum_tcpudp_magic
  11  *
  12  * this function must be called with even lengths, except
  13  * for the last fragment, which may be odd
  14  *
  15  * it's best to have buff aligned on a 32-bit boundary
  16  */
  17 asmlinkage unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
  18
  19 /*
  20  * the same as csum_partial, but copies from src while it
  21  * checksums, and handles user-space pointer exceptions correctly, when needed.
  22  *
  23  * here even more important to align src and dst on a 32-bit (or even
  24  * better 64-bit) boundary
  25  */
  26
  27 asmlinkage unsigned int csum_partial_copy_generic( const char *src, char *dst, int len, int sum,
  28                                                    int *src_err_ptr, int *dst_err_ptr);
  29
  30 /*
  31  *      Note: when you get a NULL pointer exception here this means someone
  32  *      passed in an incorrect kernel address to one of these functions.
  33  *
  34  *      If you use these functions directly please don't forget the
  35  *      verify_area().
  36  */
  37 extern __inline__
  38 unsigned int csum_partial_copy_nocheck ( const char *src, char *dst,
  39                                         int len, int sum)
  40 {
  41         return csum_partial_copy_generic ( src, dst, len, sum, NULL, NULL);
  42 }
  43
  44 extern __inline__
  45 unsigned int csum_partial_copy_from_user ( const char *src, char *dst,
  46                                                 int len, int sum, int *err_ptr)
  47 {
  48         return csum_partial_copy_generic ( src, dst, len, sum, err_ptr, NULL);
  49 }
  50
  51 #if 0
  52
  53 /* Not used at the moment. It is difficult to imagine for what purpose
  54    it can be used :-) Please, do not forget to verify_area before it --ANK
  55  */
  56
  57 /*
  58  * This combination is currently not used, but possible:
  59  */
  60
  61 extern __inline__
  62 unsigned int csum_partial_copy_to_user ( const char *src, char *dst,
  63                                         int len, int sum, int *err_ptr)
  64 {
  65         return csum_partial_copy_generic ( src, dst, len, sum, NULL, err_ptr);
  66 }
  67 #endif
  68
  69 /*
  70  * These are the old (and unsafe) way of doing checksums, a warning message will be
  71  * printed if they are used and an exeption occurs.
  72  *
  73  * these functions should go away after some time.
  74  */
  75
  76 #define csum_partial_copy_fromuser csum_partial_copy
  77 unsigned int csum_partial_copy( const char *src, char *dst, int len, int sum);
  78
  79 /*
  80  *      This is a version of ip_compute_csum() optimized for IP headers,
  81  *      which always checksum on 4 octet boundaries.
  82  *
  83  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  84  *      Arnt Gulbrandsen.
  85  */
  86 static inline unsigned short ip_fast_csum(unsigned char * iph,
  87                                           unsigned int ihl) {
  88         unsigned int sum;
  89
  90         __asm__ __volatile__("
  91             movl (%1), %0
  92             subl $4, %2
  93             jbe 2f
  94             addl 4(%1), %0
  95             adcl 8(%1), %0
  96             adcl 12(%1), %0
  97 1:          adcl 16(%1), %0
  98             lea 4(%1), %1
  99             decl %2
 100             jne 1b
 101             adcl $0, %0
 102             movl %0, %2
 103             shrl $16, %0
 104             addw %w2, %w0
 105             adcl $0, %0
 106             notl %0
 107 2:
 108             "
 109         /* Since the input registers which are loaded with iph and ipl
 110            are modified, we must also specify them as outputs, or gcc
 111            will assume they contain their original values. */
 112         : "=r" (sum), "=r" (iph), "=r" (ihl)
 113         : "1" (iph), "2" (ihl));
 114         return(sum);
 115 }
 116
 117 /*
 118  *      Fold a partial checksum
 119  */
 120
 121 static inline unsigned int csum_fold(unsigned int sum)
 122 {
 123         __asm__("
 124                 addl %1, %0
 125                 adcl $0xffff, %0
 126                 "
 127                 : "=r" (sum)
 128                 : "r" (sum << 16), "0" (sum & 0xffff0000)
 129         );
 130         return (~sum) >> 16;
 131 }
 132
 133 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 134                                                    unsigned long daddr,
 135                                                    unsigned short len,
 136                                                    unsigned short proto,
 137                                                    unsigned int sum)
 138 {
 139     __asm__("
 140         addl %1, %0
 141         adcl %2, %0
 142         adcl %3, %0
 143         adcl $0, %0
 144         "
 145         : "=r" (sum)
 146         : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));
 147     return sum;
 148 }
 149
 150 /*
 151  * computes the checksum of the TCP/UDP pseudo-header
 152  * returns a 16-bit checksum, already complemented
 153  */
 154 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
 155                                                    unsigned long daddr,
 156                                                    unsigned short len,
 157                                                    unsigned short proto,
 158                                                    unsigned int sum)
 159 {
 160         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 161 }
 162
 163 /*
 164  * this routine is used for miscellaneous IP-like checksums, mainly
 165  * in icmp.c
 166  */
 167
 168 static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {
 169     return csum_fold (csum_partial(buff, len, 0));
 170 }
 171
 172 #define _HAVE_ARCH_IPV6_CSUM
 173 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
 174                                                      struct in6_addr *daddr,
 175                                                      __u16 len,
 176                                                      unsigned short proto,
 177                                                      unsigned int sum)
 178 {
 179         __asm__("
 180                 addl 0(%1), %0
 181                 adcl 4(%1), %0
 182                 adcl 8(%1), %0
 183                 adcl 12(%1), %0
 184                 adcl 0(%2), %0
 185                 adcl 4(%2), %0
 186                 adcl 8(%2), %0
 187                 adcl 12(%2), %0
 188                 adcl %3, %0
 189                 adcl %4, %0
 190                 adcl $0, %0
 191                 "
 192                 : "=&r" (sum)
 193                 : "r" (saddr), "r" (daddr),
 194                   "r"(htonl((__u32) (len))), "r"(htonl(proto)), "0"(sum));
 195
 196         return csum_fold(sum);
 197 }
 198
 199 /*
 200  *      Copy and checksum to user
 201  */
 202 #define HAVE_CSUM_COPY_USER
 203 static __inline__ unsigned int csum_and_copy_to_user (const char *src, char *dst,
 204                                     int len, int sum, int *err_ptr)
 205 {
 206         if (access_ok(VERIFY_WRITE, dst, len))
 207                 return csum_partial_copy_generic(src, dst, len, sum, NULL, err_ptr);
 208
 209         if (len)
 210                 *err_ptr = -EFAULT;
 211
 212         return -1; /* invalid checksum */
 213 }
 214
 215 #endif