arch/um/sys-i386/shared/sysdep/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 __wsum csum_partial(const void *buff, int len, __wsum sum);
  24
  25 /*
  26  *      Note: when you get a NULL pointer exception here this means someone
  27  *      passed in an incorrect kernel address to one of these functions.
  28  *
  29  *      If you use these functions directly please don't forget the
  30  *      access_ok().
  31  */
  32
  33 static __inline__
  34 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
  35                                        int len, __wsum sum)
  36 {
  37         memcpy(dst, src, len);
  38         return csum_partial(dst, len, sum);
  39 }
  40
  41 /*
  42  * the same as csum_partial, but copies from src while it
  43  * checksums, and handles user-space pointer exceptions correctly, when needed.
  44  *
  45  * here even more important to align src and dst on a 32-bit (or even
  46  * better 64-bit) boundary
  47  */
  48
  49 static __inline__
  50 __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  51                                          int len, __wsum sum, int *err_ptr)
  52 {
  53         if (copy_from_user(dst, src, len)) {
  54                 *err_ptr = -EFAULT;
  55                 return (__force __wsum)-1;
  56         }
  57
  58         return csum_partial(dst, len, sum);
  59 }
  60
  61 /*
  62  *      This is a version of ip_compute_csum() optimized for IP headers,
  63  *      which always checksum on 4 octet boundaries.
  64  *
  65  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  66  *      Arnt Gulbrandsen.
  67  */
  68 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  69 {
  70         unsigned int sum;
  71
  72         __asm__ __volatile__(
  73             "movl (%1), %0      ;\n"
  74             "subl $4, %2        ;\n"
  75             "jbe 2f             ;\n"
  76             "addl 4(%1), %0     ;\n"
  77             "adcl 8(%1), %0     ;\n"
  78             "adcl 12(%1), %0    ;\n"
  79 "1:         adcl 16(%1), %0     ;\n"
  80             "lea 4(%1), %1      ;\n"
  81             "decl %2            ;\n"
  82             "jne 1b             ;\n"
  83             "adcl $0, %0        ;\n"
  84             "movl %0, %2        ;\n"
  85             "shrl $16, %0       ;\n"
  86             "addw %w2, %w0      ;\n"
  87             "adcl $0, %0        ;\n"
  88             "notl %0            ;\n"
  89 "2:                             ;\n"
  90         /* Since the input registers which are loaded with iph and ipl
  91            are modified, we must also specify them as outputs, or gcc
  92            will assume they contain their original values. */
  93         : "=r" (sum), "=r" (iph), "=r" (ihl)
  94         : "1" (iph), "2" (ihl)
  95         : "memory");
  96         return (__force __sum16)sum;
  97 }
  98
  99 /*
 100  *      Fold a partial checksum
 101  */
 102
 103 static inline __sum16 csum_fold(__wsum sum)
 104 {
 105         __asm__(
 106                 "addl %1, %0            ;\n"
 107                 "adcl $0xffff, %0       ;\n"
 108                 : "=r" (sum)
 109                 : "r" ((__force u32)sum << 16),
 110                   "0" ((__force u32)sum & 0xffff0000)
 111         );
 112         return (__force __sum16)(~(__force u32)sum >> 16);
 113 }
 114
 115 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 116                                                    unsigned short len,
 117                                                    unsigned short proto,
 118                                                    __wsum sum)
 119 {
 120     __asm__(
 121         "addl %1, %0    ;\n"
 122         "adcl %2, %0    ;\n"
 123         "adcl %3, %0    ;\n"
 124         "adcl $0, %0    ;\n"
 125         : "=r" (sum)
 126         : "g" (daddr), "g"(saddr), "g"((len + proto) << 8), "0"(sum));
 127     return sum;
 128 }
 129
 130 /*
 131  * computes the checksum of the TCP/UDP pseudo-header
 132  * returns a 16-bit checksum, already complemented
 133  */
 134 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 135                                                    unsigned short len,
 136                                                    unsigned short proto,
 137                                                    __wsum sum)
 138 {
 139         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 140 }
 141
 142 /*
 143  * this routine is used for miscellaneous IP-like checksums, mainly
 144  * in icmp.c
 145  */
 146
 147 static inline __sum16 ip_compute_csum(const void *buff, int len)
 148 {
 149     return csum_fold (csum_partial(buff, len, 0));
 150 }
 151
 152 #define _HAVE_ARCH_IPV6_CSUM
 153 static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 154                                           const struct in6_addr *daddr,
 155                                           __u32 len, unsigned short proto,
 156                                           __wsum sum)
 157 {
 158         __asm__(
 159                 "addl 0(%1), %0         ;\n"
 160                 "adcl 4(%1), %0         ;\n"
 161                 "adcl 8(%1), %0         ;\n"
 162                 "adcl 12(%1), %0        ;\n"
 163                 "adcl 0(%2), %0         ;\n"
 164                 "adcl 4(%2), %0         ;\n"
 165                 "adcl 8(%2), %0         ;\n"
 166                 "adcl 12(%2), %0        ;\n"
 167                 "adcl %3, %0            ;\n"
 168                 "adcl %4, %0            ;\n"
 169                 "adcl $0, %0            ;\n"
 170                 : "=&r" (sum)
 171                 : "r" (saddr), "r" (daddr),
 172                   "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
 173
 174         return csum_fold(sum);
 175 }
 176
 177 /*
 178  *      Copy and checksum to user
 179  */
 180 #define HAVE_CSUM_COPY_USER
 181 static __inline__ __wsum csum_and_copy_to_user(const void *src,
 182                                                      void __user *dst,
 183                                                      int len, __wsum sum, int *err_ptr)
 184 {
 185         if (access_ok(VERIFY_WRITE, dst, len)) {
 186                 if (copy_to_user(dst, src, len)) {
 187                         *err_ptr = -EFAULT;
 188                         return (__force __wsum)-1;
 189                 }
 190
 191                 return csum_partial(src, len, sum);
 192         }
 193
 194         if (len)
 195                 *err_ptr = -EFAULT;
 196
 197         return (__force __wsum)-1; /* invalid checksum */
 198 }
 199
 200 #endif
 201