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
   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         __wsum ret;
  53
  54         might_sleep();
  55         stac();
  56         ret = csum_partial_copy_generic((__force void *)src, dst,
  57                                         len, sum, err_ptr, NULL);
  58         clac();
  59
  60         return ret;
  61 }
  62
  63 /*
  64  *      This is a version of ip_compute_csum() optimized for IP headers,
  65  *      which always checksum on 4 octet boundaries.
  66  *
  67  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  68  *      Arnt Gulbrandsen.
  69  */
  70 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  71 {
  72         unsigned int sum;
  73
  74         asm volatile("movl (%1), %0     ;\n"
  75                      "subl $4, %2       ;\n"
  76                      "jbe 2f            ;\n"
  77                      "addl 4(%1), %0    ;\n"
  78                      "adcl 8(%1), %0    ;\n"
  79                      "adcl 12(%1), %0;\n"
  80                      "1:        adcl 16(%1), %0 ;\n"
  81                      "lea 4(%1), %1     ;\n"
  82                      "decl %2   ;\n"
  83                      "jne 1b            ;\n"
  84                      "adcl $0, %0       ;\n"
  85                      "movl %0, %2       ;\n"
  86                      "shrl $16, %0      ;\n"
  87                      "addw %w2, %w0     ;\n"
  88                      "adcl $0, %0       ;\n"
  89                      "notl %0   ;\n"
  90                      "2:                ;\n"
  91         /* Since the input registers which are loaded with iph and ihl
  92            are modified, we must also specify them as outputs, or gcc
  93            will assume they contain their original values. */
  94                      : "=r" (sum), "=r" (iph), "=r" (ihl)
  95                      : "1" (iph), "2" (ihl)
  96                      : "memory");
  97         return (__force __sum16)sum;
  98 }
  99
 100 /*
 101  *      Fold a partial checksum
 102  */
 103
 104 static inline __sum16 csum_fold(__wsum sum)
 105 {
 106         asm("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         return (__force __sum16)(~(__force u32)sum >> 16);
 112 }
 113
 114 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 115                                         unsigned short len,
 116                                         unsigned short proto,
 117                                         __wsum sum)
 118 {
 119         asm("addl %1, %0        ;\n"
 120             "adcl %2, %0        ;\n"
 121             "adcl %3, %0        ;\n"
 122             "adcl $0, %0        ;\n"
 123             : "=r" (sum)
 124             : "g" (daddr), "g"(saddr),
 125               "g" ((len + proto) << 8), "0" (sum));
 126         return sum;
 127 }
 128
 129 /*
 130  * computes the checksum of the TCP/UDP pseudo-header
 131  * returns a 16-bit checksum, already complemented
 132  */
 133 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 134                                         unsigned short len,
 135                                         unsigned short proto,
 136                                         __wsum sum)
 137 {
 138         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 139 }
 140
 141 /*
 142  * this routine is used for miscellaneous IP-like checksums, mainly
 143  * in icmp.c
 144  */
 145
 146 static inline __sum16 ip_compute_csum(const void *buff, int len)
 147 {
 148     return csum_fold(csum_partial(buff, len, 0));
 149 }
 150
 151 #define _HAVE_ARCH_IPV6_CSUM
 152 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 153                                       const struct in6_addr *daddr,
 154                                       __u32 len, unsigned short proto,
 155                                       __wsum sum)
 156 {
 157         asm("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             : "memory");
 172
 173         return csum_fold(sum);
 174 }
 175
 176 /*
 177  *      Copy and checksum to user
 178  */
 179 #define HAVE_CSUM_COPY_USER
 180 static inline __wsum csum_and_copy_to_user(const void *src,
 181                                            void __user *dst,
 182                                            int len, __wsum sum,
 183                                            int *err_ptr)
 184 {
 185         __wsum ret;
 186
 187         might_sleep();
 188         if (access_ok(VERIFY_WRITE, dst, len)) {
 189                 stac();
 190                 ret = csum_partial_copy_generic(src, (__force void *)dst,
 191                                                 len, sum, NULL, err_ptr);
 192                 clac();
 193                 return ret;
 194         }
 195
 196         if (len)
 197                 *err_ptr = -EFAULT;
 198
 199         return (__force __wsum)-1; /* invalid checksum */
 200 }
 201
 202 #endif /* _ASM_X86_CHECKSUM_32_H */