arch/x86/include/asm/checksum_32.h

   1 #ifndef _ASM_X86_CHECKSUM_32_H
   2 #define _ASM_X86_CHECKSUM_32_H
   3
   4 #include <linux/in6.h>
   5 #include <linux/uaccess.h>
   6
   7 /*
   8  * computes the checksum of a memory block at buff, length len,
   9  * and adds in "sum" (32-bit)
  10  *
  11  * returns a 32-bit number suitable for feeding into itself
  12  * or csum_tcpudp_magic
  13  *
  14  * this function must be called with even lengths, except
  15  * for the last fragment, which may be odd
  16  *
  17  * it's best to have buff aligned on a 32-bit boundary
  18  */
  19 asmlinkage __wsum csum_partial(const void *buff, int len, __wsum sum);
  20
  21 /*
  22  * the same as csum_partial, but copies from src while it
  23  * checksums, and handles user-space pointer exceptions correctly, when needed.
  24  *
  25  * here even more important to align src and dst on a 32-bit (or even
  26  * better 64-bit) boundary
  27  */
  28
  29 asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst,
  30                                             int len, __wsum sum,
  31                                             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 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
  41                                                int len, __wsum sum)
  42 {
  43         return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
  44 }
  45
  46 static inline __wsum csum_partial_copy_from_user(const void __user *src,
  47                                                  void *dst,
  48                                                  int len, __wsum sum,
  49                                                  int *err_ptr)
  50 {
  51         __wsum ret;
  52
  53         might_sleep();
  54         stac();
  55         ret = csum_partial_copy_generic((__force void *)src, dst,
  56                                         len, sum, err_ptr, NULL);
  57         clac();
  58
  59         return ret;
  60 }
  61
  62 /*
  63  *      This is a version of ip_compute_csum() optimized for IP headers,
  64  *      which always checksum on 4 octet boundaries.
  65  *
  66  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  67  *      Arnt Gulbrandsen.
  68  */
  69 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  70 {
  71         unsigned int sum;
  72
  73         asm volatile("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 ihl
  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("addl %1, %0                ;\n"
 106             "adcl $0xffff, %0   ;\n"
 107             : "=r" (sum)
 108             : "r" ((__force u32)sum << 16),
 109               "0" ((__force u32)sum & 0xffff0000));
 110         return (__force __sum16)(~(__force u32)sum >> 16);
 111 }
 112
 113 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 114                                         __u32 len, __u8 proto,
 115                                         __wsum sum)
 116 {
 117         asm("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),
 123               "g" ((len + proto) << 8), "0" (sum));
 124         return sum;
 125 }
 126
 127 /*
 128  * computes the checksum of the TCP/UDP pseudo-header
 129  * returns a 16-bit checksum, already complemented
 130  */
 131 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 132                                         __u32 len, __u8 proto,
 133                                         __wsum sum)
 134 {
 135         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 136 }
 137
 138 /*
 139  * this routine is used for miscellaneous IP-like checksums, mainly
 140  * in icmp.c
 141  */
 142
 143 static inline __sum16 ip_compute_csum(const void *buff, int len)
 144 {
 145     return csum_fold(csum_partial(buff, len, 0));
 146 }
 147
 148 #define _HAVE_ARCH_IPV6_CSUM
 149 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 150                                       const struct in6_addr *daddr,
 151                                       __u32 len, __u8 proto, __wsum sum)
 152 {
 153         asm("addl 0(%1), %0     ;\n"
 154             "adcl 4(%1), %0     ;\n"
 155             "adcl 8(%1), %0     ;\n"
 156             "adcl 12(%1), %0    ;\n"
 157             "adcl 0(%2), %0     ;\n"
 158             "adcl 4(%2), %0     ;\n"
 159             "adcl 8(%2), %0     ;\n"
 160             "adcl 12(%2), %0    ;\n"
 161             "adcl %3, %0        ;\n"
 162             "adcl %4, %0        ;\n"
 163             "adcl $0, %0        ;\n"
 164             : "=&r" (sum)
 165             : "r" (saddr), "r" (daddr),
 166               "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
 167             : "memory");
 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         __wsum ret;
 182
 183         might_sleep();
 184         if (access_ok(VERIFY_WRITE, dst, len)) {
 185                 stac();
 186                 ret = csum_partial_copy_generic(src, (__force void *)dst,
 187                                                 len, sum, NULL, err_ptr);
 188                 clac();
 189                 return ret;
 190         }
 191
 192         if (len)
 193                 *err_ptr = -EFAULT;
 194
 195         return (__force __wsum)-1; /* invalid checksum */
 196 }
 197
 198 #endif /* _ASM_X86_CHECKSUM_32_H */