include/asm-x86/checksum_32.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,
  32                                             int *src_err_ptr, int *dst_err_ptr);
  33
  34 /*
  35  *      Note: when you get a NULL pointer exception here this means someone
  36  *      passed in an incorrect kernel address to one of these functions.
  37  *
  38  *      If you use these functions directly please don't forget the
  39  *      access_ok().
  40  */
  41 static inline __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 __wsum csum_partial_copy_from_user(const void __user *src,
  48                                                  void *dst,
  49                                                  int len, __wsum sum,
  50                                                  int *err_ptr)
  51 {
  52         might_sleep();
  53         return csum_partial_copy_generic((__force void *)src, dst,
  54                                          len, sum, err_ptr, NULL);
  55 }
  56
  57 /*
  58  *      This is a version of ip_compute_csum() optimized for IP headers,
  59  *      which always checksum on 4 octet boundaries.
  60  *
  61  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  62  *      Arnt Gulbrandsen.
  63  */
  64 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  65 {
  66         unsigned int sum;
  67
  68         asm volatile("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("addl %1, %0                ;\n"
 101             "adcl $0xffff, %0   ;\n"
 102             : "=r" (sum)
 103             : "r" ((__force u32)sum << 16),
 104               "0" ((__force u32)sum & 0xffff0000));
 105         return (__force __sum16)(~(__force u32)sum >> 16);
 106 }
 107
 108 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 109                                         unsigned short len,
 110                                         unsigned short proto,
 111                                         __wsum sum)
 112 {
 113         asm("addl %1, %0        ;\n"
 114             "adcl %2, %0        ;\n"
 115             "adcl %3, %0        ;\n"
 116             "adcl $0, %0        ;\n"
 117             : "=r" (sum)
 118             : "g" (daddr), "g"(saddr),
 119               "g" ((len + proto) << 8), "0" (sum));
 120         return sum;
 121 }
 122
 123 /*
 124  * computes the checksum of the TCP/UDP pseudo-header
 125  * returns a 16-bit checksum, already complemented
 126  */
 127 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 128                                         unsigned short len,
 129                                         unsigned short proto,
 130                                         __wsum sum)
 131 {
 132         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 133 }
 134
 135 /*
 136  * this routine is used for miscellaneous IP-like checksums, mainly
 137  * in icmp.c
 138  */
 139
 140 static inline __sum16 ip_compute_csum(const void *buff, int len)
 141 {
 142     return csum_fold(csum_partial(buff, len, 0));
 143 }
 144
 145 #define _HAVE_ARCH_IPV6_CSUM
 146 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 147                                       const struct in6_addr *daddr,
 148                                       __u32 len, unsigned short proto,
 149                                       __wsum sum)
 150 {
 151         asm("addl 0(%1), %0     ;\n"
 152             "adcl 4(%1), %0     ;\n"
 153             "adcl 8(%1), %0     ;\n"
 154             "adcl 12(%1), %0    ;\n"
 155             "adcl 0(%2), %0     ;\n"
 156             "adcl 4(%2), %0     ;\n"
 157             "adcl 8(%2), %0     ;\n"
 158             "adcl 12(%2), %0    ;\n"
 159             "adcl %3, %0        ;\n"
 160             "adcl %4, %0        ;\n"
 161             "adcl $0, %0        ;\n"
 162             : "=&r" (sum)
 163             : "r" (saddr), "r" (daddr),
 164               "r" (htonl(len)), "r" (htonl(proto)), "0" (sum));
 165
 166         return csum_fold(sum);
 167 }
 168
 169 /*
 170  *      Copy and checksum to user
 171  */
 172 #define HAVE_CSUM_COPY_USER
 173 static inline __wsum csum_and_copy_to_user(const void *src,
 174                                            void __user *dst,
 175                                            int len, __wsum sum,
 176                                            int *err_ptr)
 177 {
 178         might_sleep();
 179         if (access_ok(VERIFY_WRITE, dst, len))
 180                 return csum_partial_copy_generic(src, (__force void *)dst,
 181                                                  len, sum, NULL, err_ptr);
 182
 183         if (len)
 184                 *err_ptr = -EFAULT;
 185
 186         return (__force __wsum)-1; /* invalid checksum */
 187 }
 188
 189 #endif