include/asm-i386/checksum.h

   1 #ifndef _I386_CHECKSUM_H
   2 #define _I386_CHECKSUM_H
   3
   4 #include <linux/in6.h>
   5
   6 /*
   7  * computes the checksum of a memory block at buff, length len,
   8  * and adds in "sum" (32-bit)
   9  *
  10  * returns a 32-bit number suitable for feeding into itself
  11  * or csum_tcpudp_magic
  12  *
  13  * this function must be called with even lengths, except
  14  * for the last fragment, which may be odd
  15  *
  16  * it's best to have buff aligned on a 32-bit boundary
  17  */
  18 asmlinkage unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
  19
  20 /*
  21  * the same as csum_partial, but copies from src while it
  22  * checksums, and handles user-space pointer exceptions correctly, when needed.
  23  *
  24  * here even more important to align src and dst on a 32-bit (or even
  25  * better 64-bit) boundary
  26  */
  27
  28 asmlinkage unsigned int csum_partial_copy_generic(const unsigned char *src, unsigned char *dst,
  29                                                   int len, int sum, int *src_err_ptr, int *dst_err_ptr);
  30
  31 /*
  32  *      Note: when you get a NULL pointer exception here this means someone
  33  *      passed in an incorrect kernel address to one of these functions.
  34  *
  35  *      If you use these functions directly please don't forget the
  36  *      verify_area().
  37  */
  38 static __inline__
  39 unsigned int csum_partial_copy_nocheck (const unsigned char *src, unsigned char *dst,
  40                                         int len, int sum)
  41 {
  42         return csum_partial_copy_generic ( src, dst, len, sum, NULL, NULL);
  43 }
  44
  45 static __inline__
  46 unsigned int csum_partial_copy_from_user(const unsigned char __user *src, unsigned char *dst,
  47                                                 int len, int sum, int *err_ptr)
  48 {
  49         might_sleep();
  50         return csum_partial_copy_generic((__force unsigned char *)src, dst,
  51                                         len, sum, err_ptr, NULL);
  52 }
  53
  54 /*
  55  *      This is a version of ip_compute_csum() optimized for IP headers,
  56  *      which always checksum on 4 octet boundaries.
  57  *
  58  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  59  *      Arnt Gulbrandsen.
  60  */
  61 static inline unsigned short ip_fast_csum(unsigned char * iph,
  62                                           unsigned int ihl)
  63 {
  64         unsigned int sum;
  65
  66         __asm__ __volatile__(
  67             "movl (%1), %0      ;\n"
  68             "subl $4, %2        ;\n"
  69             "jbe 2f             ;\n"
  70             "addl 4(%1), %0     ;\n"
  71             "adcl 8(%1), %0     ;\n"
  72             "adcl 12(%1), %0    ;\n"
  73 "1:         adcl 16(%1), %0     ;\n"
  74             "lea 4(%1), %1      ;\n"
  75             "decl %2            ;\n"
  76             "jne 1b             ;\n"
  77             "adcl $0, %0        ;\n"
  78             "movl %0, %2        ;\n"
  79             "shrl $16, %0       ;\n"
  80             "addw %w2, %w0      ;\n"
  81             "adcl $0, %0        ;\n"
  82             "notl %0            ;\n"
  83 "2:                             ;\n"
  84         /* Since the input registers which are loaded with iph and ipl
  85            are modified, we must also specify them as outputs, or gcc
  86            will assume they contain their original values. */
  87         : "=r" (sum), "=r" (iph), "=r" (ihl)
  88         : "1" (iph), "2" (ihl)
  89         : "memory");
  90         return(sum);
  91 }
  92
  93 /*
  94  *      Fold a partial checksum
  95  */
  96
  97 static inline unsigned int csum_fold(unsigned int sum)
  98 {
  99         __asm__(
 100                 "addl %1, %0            ;\n"
 101                 "adcl $0xffff, %0       ;\n"
 102                 : "=r" (sum)
 103                 : "r" (sum << 16), "0" (sum & 0xffff0000)
 104         );
 105         return (~sum) >> 16;
 106 }
 107
 108 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 109                                                    unsigned long daddr,
 110                                                    unsigned short len,
 111                                                    unsigned short proto,
 112                                                    unsigned int sum)
 113 {
 114     __asm__(
 115         "addl %1, %0    ;\n"
 116         "adcl %2, %0    ;\n"
 117         "adcl %3, %0    ;\n"
 118         "adcl $0, %0    ;\n"
 119         : "=r" (sum)
 120         : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));
 121     return sum;
 122 }
 123
 124 /*
 125  * computes the checksum of the TCP/UDP pseudo-header
 126  * returns a 16-bit checksum, already complemented
 127  */
 128 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
 129                                                    unsigned long daddr,
 130                                                    unsigned short len,
 131                                                    unsigned short proto,
 132                                                    unsigned int sum)
 133 {
 134         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 135 }
 136
 137 /*
 138  * this routine is used for miscellaneous IP-like checksums, mainly
 139  * in icmp.c
 140  */
 141
 142 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
 143 {
 144     return csum_fold (csum_partial(buff, len, 0));
 145 }
 146
 147 #define _HAVE_ARCH_IPV6_CSUM
 148 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
 149                                                      struct in6_addr *daddr,
 150                                                      __u32 len,
 151                                                      unsigned short proto,
 152                                                      unsigned int sum)
 153 {
 154         __asm__(
 155                 "addl 0(%1), %0         ;\n"
 156                 "adcl 4(%1), %0         ;\n"
 157                 "adcl 8(%1), %0         ;\n"
 158                 "adcl 12(%1), %0        ;\n"
 159                 "adcl 0(%2), %0         ;\n"
 160                 "adcl 4(%2), %0         ;\n"
 161                 "adcl 8(%2), %0         ;\n"
 162                 "adcl 12(%2), %0        ;\n"
 163                 "adcl %3, %0            ;\n"
 164                 "adcl %4, %0            ;\n"
 165                 "adcl $0, %0            ;\n"
 166                 : "=&r" (sum)
 167                 : "r" (saddr), "r" (daddr),
 168                   "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
 169
 170         return csum_fold(sum);
 171 }
 172
 173 /*
 174  *      Copy and checksum to user
 175  */
 176 #define HAVE_CSUM_COPY_USER
 177 static __inline__ unsigned int csum_and_copy_to_user(const unsigned char *src,
 178                                                      unsigned char __user *dst,
 179                                                      int len, int sum,
 180                                                      int *err_ptr)
 181 {
 182         might_sleep();
 183         if (access_ok(VERIFY_WRITE, dst, len))
 184                 return csum_partial_copy_generic(src, (__force unsigned char *)dst, len, sum, NULL, err_ptr);
 185
 186         if (len)
 187                 *err_ptr = -EFAULT;
 188
 189         return -1; /* invalid checksum */
 190 }
 191
 192 #endif