include/asm-i386/checksum.h

   1 #ifndef _I386_CHECKSUM_H
   2 #define _I386_CHECKSUM_H
   3
   4 #include <linux/in6.h>
   5
   6 #include <asm/uaccess.h>
   7
   8 /*
   9  * computes the checksum of a memory block at buff, length len,
  10  * and adds in "sum" (32-bit)
  11  *
  12  * returns a 32-bit number suitable for feeding into itself
  13  * or csum_tcpudp_magic
  14  *
  15  * this function must be called with even lengths, except
  16  * for the last fragment, which may be odd
  17  *
  18  * it's best to have buff aligned on a 32-bit boundary
  19  */
  20 asmlinkage unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
  21
  22 /*
  23  * the same as csum_partial, but copies from src while it
  24  * checksums, and handles user-space pointer exceptions correctly, when needed.
  25  *
  26  * here even more important to align src and dst on a 32-bit (or even
  27  * better 64-bit) boundary
  28  */
  29
  30 asmlinkage unsigned int csum_partial_copy_generic(const unsigned char *src, unsigned char *dst,
  31                                                   int len, int sum, int *src_err_ptr, int *dst_err_ptr);
  32
  33 /*
  34  *      Note: when you get a NULL pointer exception here this means someone
  35  *      passed in an incorrect kernel address to one of these functions.
  36  *
  37  *      If you use these functions directly please don't forget the
  38  *      access_ok().
  39  */
  40 static __inline__
  41 unsigned int csum_partial_copy_nocheck (const unsigned char *src, unsigned char *dst,
  42                                         int len, int sum)
  43 {
  44         return csum_partial_copy_generic ( src, dst, len, sum, NULL, NULL);
  45 }
  46
  47 static __inline__
  48 unsigned int csum_partial_copy_from_user(const unsigned char __user *src, unsigned char *dst,
  49                                                 int len, int sum, int *err_ptr)
  50 {
  51         might_sleep();
  52         return csum_partial_copy_generic((__force unsigned char *)src, dst,
  53                                         len, sum, err_ptr, NULL);
  54 }
  55
  56 /*
  57  *      This is a version of ip_compute_csum() optimized for IP headers,
  58  *      which always checksum on 4 octet boundaries.
  59  *
  60  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  61  *      Arnt Gulbrandsen.
  62  */
  63 static inline unsigned short ip_fast_csum(unsigned char * iph,
  64                                           unsigned int ihl)
  65 {
  66         unsigned int sum;
  67
  68         __asm__ __volatile__(
  69             "movl (%1), %0      ;\n"
  70             "subl $4, %2        ;\n"
  71             "jbe 2f             ;\n"
  72             "addl 4(%1), %0     ;\n"
  73             "adcl 8(%1), %0     ;\n"
  74             "adcl 12(%1), %0    ;\n"
  75 "1:         adcl 16(%1), %0     ;\n"
  76             "lea 4(%1), %1      ;\n"
  77             "decl %2            ;\n"
  78             "jne 1b             ;\n"
  79             "adcl $0, %0        ;\n"
  80             "movl %0, %2        ;\n"
  81             "shrl $16, %0       ;\n"
  82             "addw %w2, %w0      ;\n"
  83             "adcl $0, %0        ;\n"
  84             "notl %0            ;\n"
  85 "2:                             ;\n"
  86         /* Since the input registers which are loaded with iph and ihl
  87            are modified, we must also specify them as outputs, or gcc
  88            will assume they contain their original values. */
  89         : "=r" (sum), "=r" (iph), "=r" (ihl)
  90         : "1" (iph), "2" (ihl)
  91         : "memory");
  92         return(sum);
  93 }
  94
  95 /*
  96  *      Fold a partial checksum
  97  */
  98
  99 static inline unsigned int csum_fold(unsigned int sum)
 100 {
 101         __asm__(
 102                 "addl %1, %0            ;\n"
 103                 "adcl $0xffff, %0       ;\n"
 104                 : "=r" (sum)
 105                 : "r" (sum << 16), "0" (sum & 0xffff0000)
 106         );
 107         return (~sum) >> 16;
 108 }
 109
 110 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 111                                                    unsigned long daddr,
 112                                                    unsigned short len,
 113                                                    unsigned short proto,
 114                                                    unsigned int sum)
 115 {
 116     __asm__(
 117         "addl %1, %0    ;\n"
 118         "adcl %2, %0    ;\n"
 119         "adcl %3, %0    ;\n"
 120         "adcl $0, %0    ;\n"
 121         : "=r" (sum)
 122         : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));
 123     return sum;
 124 }
 125
 126 /*
 127  * computes the checksum of the TCP/UDP pseudo-header
 128  * returns a 16-bit checksum, already complemented
 129  */
 130 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
 131                                                    unsigned long daddr,
 132                                                    unsigned short len,
 133                                                    unsigned short proto,
 134                                                    unsigned int sum)
 135 {
 136         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 137 }
 138
 139 /*
 140  * this routine is used for miscellaneous IP-like checksums, mainly
 141  * in icmp.c
 142  */
 143
 144 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
 145 {
 146     return csum_fold (csum_partial(buff, len, 0));
 147 }
 148
 149 #define _HAVE_ARCH_IPV6_CSUM
 150 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
 151                                                      struct in6_addr *daddr,
 152                                                      __u32 len,
 153                                                      unsigned short proto,
 154                                                      unsigned int sum)
 155 {
 156         __asm__(
 157                 "addl 0(%1), %0         ;\n"
 158                 "adcl 4(%1), %0         ;\n"
 159                 "adcl 8(%1), %0         ;\n"
 160                 "adcl 12(%1), %0        ;\n"
 161                 "adcl 0(%2), %0         ;\n"
 162                 "adcl 4(%2), %0         ;\n"
 163                 "adcl 8(%2), %0         ;\n"
 164                 "adcl 12(%2), %0        ;\n"
 165                 "adcl %3, %0            ;\n"
 166                 "adcl %4, %0            ;\n"
 167                 "adcl $0, %0            ;\n"
 168                 : "=&r" (sum)
 169                 : "r" (saddr), "r" (daddr),
 170                   "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
 171
 172         return csum_fold(sum);
 173 }
 174
 175 /*
 176  *      Copy and checksum to user
 177  */
 178 #define HAVE_CSUM_COPY_USER
 179 static __inline__ unsigned int csum_and_copy_to_user(const unsigned char *src,
 180                                                      unsigned char __user *dst,
 181                                                      int len, int sum,
 182                                                      int *err_ptr)
 183 {
 184         might_sleep();
 185         if (access_ok(VERIFY_WRITE, dst, len))
 186                 return csum_partial_copy_generic(src, (__force unsigned char *)dst, len, sum, NULL, err_ptr);
 187
 188         if (len)
 189                 *err_ptr = -EFAULT;
 190
 191         return -1; /* invalid checksum */
 192 }
 193
 194 #endif