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 __wsum csum_partial(const void *buff, int len, __wsum 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 __wsum csum_partial_copy_generic(const void *src, void *dst,
  31                                                   int len, __wsum 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 __wsum csum_partial_copy_nocheck (const void *src, void *dst,
  42                                         int len, __wsum sum)
  43 {
  44         return csum_partial_copy_generic ( src, dst, len, sum, NULL, NULL);
  45 }
  46
  47 static __inline__
  48 __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  49                                                 int len, __wsum sum, int *err_ptr)
  50 {
  51         might_sleep();
  52         return csum_partial_copy_generic((__force void *)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 __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  64 {
  65         unsigned int sum;
  66
  67         __asm__ __volatile__(
  68             "movl (%1), %0      ;\n"
  69             "subl $4, %2        ;\n"
  70             "jbe 2f             ;\n"
  71             "addl 4(%1), %0     ;\n"
  72             "adcl 8(%1), %0     ;\n"
  73             "adcl 12(%1), %0    ;\n"
  74 "1:         adcl 16(%1), %0     ;\n"
  75             "lea 4(%1), %1      ;\n"
  76             "decl %2            ;\n"
  77             "jne 1b             ;\n"
  78             "adcl $0, %0        ;\n"
  79             "movl %0, %2        ;\n"
  80             "shrl $16, %0       ;\n"
  81             "addw %w2, %w0      ;\n"
  82             "adcl $0, %0        ;\n"
  83             "notl %0            ;\n"
  84 "2:                             ;\n"
  85         /* Since the input registers which are loaded with iph and ihl
  86            are modified, we must also specify them as outputs, or gcc
  87            will assume they contain their original values. */
  88         : "=r" (sum), "=r" (iph), "=r" (ihl)
  89         : "1" (iph), "2" (ihl)
  90         : "memory");
  91         return (__force __sum16)sum;
  92 }
  93
  94 /*
  95  *      Fold a partial checksum
  96  */
  97
  98 static inline __sum16 csum_fold(__wsum sum)
  99 {
 100         __asm__(
 101                 "addl %1, %0            ;\n"
 102                 "adcl $0xffff, %0       ;\n"
 103                 : "=r" (sum)
 104                 : "r" ((__force u32)sum << 16),
 105                   "0" ((__force u32)sum & 0xffff0000)
 106         );
 107         return (__force __sum16)(~(__force u32)sum >> 16);
 108 }
 109
 110 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 111                                            unsigned short len,
 112                                            unsigned short proto,
 113                                            __wsum sum)
 114 {
 115     __asm__(
 116         "addl %1, %0    ;\n"
 117         "adcl %2, %0    ;\n"
 118         "adcl %3, %0    ;\n"
 119         "adcl $0, %0    ;\n"
 120         : "=r" (sum)
 121         : "g" (daddr), "g"(saddr), "g"((len + proto) << 8), "0"(sum));
 122     return sum;
 123 }
 124
 125 /*
 126  * computes the checksum of the TCP/UDP pseudo-header
 127  * returns a 16-bit checksum, already complemented
 128  */
 129 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 130                                                    unsigned short len,
 131                                                    unsigned short proto,
 132                                                    __wsum 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 __sum16 ip_compute_csum(const void *buff, int len)
 143 {
 144     return csum_fold (csum_partial(buff, len, 0));
 145 }
 146
 147 #define _HAVE_ARCH_IPV6_CSUM
 148 static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 149                                           const struct in6_addr *daddr,
 150                                           __u32 len, unsigned short proto,
 151                                           __wsum sum)
 152 {
 153         __asm__(
 154                 "addl 0(%1), %0         ;\n"
 155                 "adcl 4(%1), %0         ;\n"
 156                 "adcl 8(%1), %0         ;\n"
 157                 "adcl 12(%1), %0        ;\n"
 158                 "adcl 0(%2), %0         ;\n"
 159                 "adcl 4(%2), %0         ;\n"
 160                 "adcl 8(%2), %0         ;\n"
 161                 "adcl 12(%2), %0        ;\n"
 162                 "adcl %3, %0            ;\n"
 163                 "adcl %4, %0            ;\n"
 164                 "adcl $0, %0            ;\n"
 165                 : "=&r" (sum)
 166                 : "r" (saddr), "r" (daddr),
 167                   "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
 168
 169         return csum_fold(sum);
 170 }
 171
 172 /*
 173  *      Copy and checksum to user
 174  */
 175 #define HAVE_CSUM_COPY_USER
 176 static __inline__ __wsum csum_and_copy_to_user(const void *src,
 177                                                      void __user *dst,
 178                                                      int len, __wsum sum,
 179                                                      int *err_ptr)
 180 {
 181         might_sleep();
 182         if (access_ok(VERIFY_WRITE, dst, len))
 183                 return csum_partial_copy_generic(src, (__force void *)dst, len, sum, NULL, err_ptr);
 184
 185         if (len)
 186                 *err_ptr = -EFAULT;
 187
 188         return (__force __wsum)-1; /* invalid checksum */
 189 }
 190
 191 #endif