include/asm-powerpc/checksum.h

   1 #ifndef _ASM_POWERPC_CHECKSUM_H
   2 #define _ASM_POWERPC_CHECKSUM_H
   3 #ifdef __KERNEL__
   4
   5 /*
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 /*
  13  * This is a version of ip_compute_csum() optimized for IP headers,
  14  * which always checksum on 4 octet boundaries.  ihl is the number
  15  * of 32-bit words and is always >= 5.
  16  */
  17 extern unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl);
  18
  19 /*
  20  * computes the checksum of the TCP/UDP pseudo-header
  21  * returns a 16-bit checksum, already complemented
  22  */
  23 extern unsigned short csum_tcpudp_magic(unsigned long saddr,
  24                                         unsigned long daddr,
  25                                         unsigned short len,
  26                                         unsigned short proto,
  27                                         unsigned int sum);
  28
  29 /*
  30  * computes the checksum of a memory block at buff, length len,
  31  * and adds in "sum" (32-bit)
  32  *
  33  * returns a 32-bit number suitable for feeding into itself
  34  * or csum_tcpudp_magic
  35  *
  36  * this function must be called with even lengths, except
  37  * for the last fragment, which may be odd
  38  *
  39  * it's best to have buff aligned on a 32-bit boundary
  40  */
  41 extern unsigned int csum_partial(const unsigned char * buff, int len,
  42                                  unsigned int sum);
  43
  44 /*
  45  * Computes the checksum of a memory block at src, length len,
  46  * and adds in "sum" (32-bit), while copying the block to dst.
  47  * If an access exception occurs on src or dst, it stores -EFAULT
  48  * to *src_err or *dst_err respectively (if that pointer is not
  49  * NULL), and, for an error on src, zeroes the rest of dst.
  50  *
  51  * Like csum_partial, this must be called with even lengths,
  52  * except for the last fragment.
  53  */
  54 extern unsigned int csum_partial_copy_generic(const char *src, char *dst,
  55                                               int len, unsigned int sum,
  56                                               int *src_err, int *dst_err);
  57 /*
  58  * the same as csum_partial, but copies from src to dst while it
  59  * checksums.
  60  */
  61 unsigned int csum_partial_copy_nocheck(const char *src,
  62                                        char *dst,
  63                                        int len,
  64                                        unsigned int sum);
  65
  66 #define csum_partial_copy_from_user(src, dst, len, sum, errp)   \
  67         csum_partial_copy_generic((src), (dst), (len), (sum), (errp), NULL)
  68
  69 #define csum_partial_copy_nocheck(src, dst, len, sum)   \
  70         csum_partial_copy_generic((src), (dst), (len), (sum), NULL, NULL)
  71
  72
  73 /*
  74  * turns a 32-bit partial checksum (e.g. from csum_partial) into a
  75  * 1's complement 16-bit checksum.
  76  */
  77 static inline unsigned int csum_fold(unsigned int sum)
  78 {
  79         unsigned int tmp;
  80
  81         /* swap the two 16-bit halves of sum */
  82         __asm__("rlwinm %0,%1,16,0,31" : "=r" (tmp) : "r" (sum));
  83         /* if there is a carry from adding the two 16-bit halves,
  84            it will carry from the lower half into the upper half,
  85            giving us the correct sum in the upper half. */
  86         sum = ~(sum + tmp) >> 16;
  87         return sum;
  88 }
  89
  90 /*
  91  * this routine is used for miscellaneous IP-like checksums, mainly
  92  * in icmp.c
  93  */
  94 static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
  95 {
  96         return csum_fold(csum_partial(buff, len, 0));
  97 }
  98
  99 #ifdef __powerpc64__
 100 static inline u32 csum_tcpudp_nofold(u32 saddr,
 101                                      u32 daddr,
 102                                      unsigned short len,
 103                                      unsigned short proto,
 104                                      unsigned int sum)
 105 {
 106         unsigned long s = sum;
 107
 108         s += saddr;
 109         s += daddr;
 110         s += (proto << 16) + len;
 111         s += (s >> 32);
 112         return (u32) s;
 113 }
 114 #else
 115 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
 116                                                    unsigned long daddr,
 117                                                    unsigned short len,
 118                                                    unsigned short proto,
 119                                                    unsigned int sum)
 120 {
 121     __asm__("\n\
 122         addc %0,%0,%1 \n\
 123         adde %0,%0,%2 \n\
 124         adde %0,%0,%3 \n\
 125         addze %0,%0 \n\
 126         "
 127         : "=r" (sum)
 128         : "r" (daddr), "r"(saddr), "r"((proto<<16)+len), "0"(sum));
 129     return sum;
 130 }
 131
 132 #endif
 133 #endif /* __KERNEL__ */
 134 #endif