arch/powerpc/include/asm/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 __sum16 ip_fast_csum(const void *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 __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
  24                                         unsigned short len,
  25                                         unsigned short proto,
  26                                         __wsum sum);
  27
  28 /*
  29  * computes the checksum of a memory block at buff, length len,
  30  * and adds in "sum" (32-bit)
  31  *
  32  * returns a 32-bit number suitable for feeding into itself
  33  * or csum_tcpudp_magic
  34  *
  35  * this function must be called with even lengths, except
  36  * for the last fragment, which may be odd
  37  *
  38  * it's best to have buff aligned on a 32-bit boundary
  39  */
  40 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  41
  42 /*
  43  * Computes the checksum of a memory block at src, length len,
  44  * and adds in "sum" (32-bit), while copying the block to dst.
  45  * If an access exception occurs on src or dst, it stores -EFAULT
  46  * to *src_err or *dst_err respectively (if that pointer is not
  47  * NULL), and, for an error on src, zeroes the rest of dst.
  48  *
  49  * Like csum_partial, this must be called with even lengths,
  50  * except for the last fragment.
  51  */
  52 extern __wsum csum_partial_copy_generic(const void *src, void *dst,
  53                                               int len, __wsum sum,
  54                                               int *src_err, int *dst_err);
  55 /*
  56  * the same as csum_partial, but copies from src to dst while it
  57  * checksums.
  58  */
  59 #define csum_partial_copy_from_user(src, dst, len, sum, errp)   \
  60         csum_partial_copy_generic((__force const void *)(src), (dst), (len), (sum), (errp), NULL)
  61
  62 #define csum_partial_copy_nocheck(src, dst, len, sum)   \
  63         csum_partial_copy_generic((src), (dst), (len), (sum), NULL, NULL)
  64
  65
  66 /*
  67  * turns a 32-bit partial checksum (e.g. from csum_partial) into a
  68  * 1's complement 16-bit checksum.
  69  */
  70 static inline __sum16 csum_fold(__wsum sum)
  71 {
  72         unsigned int tmp;
  73
  74         /* swap the two 16-bit halves of sum */
  75         __asm__("rlwinm %0,%1,16,0,31" : "=r" (tmp) : "r" (sum));
  76         /* if there is a carry from adding the two 16-bit halves,
  77            it will carry from the lower half into the upper half,
  78            giving us the correct sum in the upper half. */
  79         return (__force __sum16)(~((__force u32)sum + tmp) >> 16);
  80 }
  81
  82 /*
  83  * this routine is used for miscellaneous IP-like checksums, mainly
  84  * in icmp.c
  85  */
  86 static inline __sum16 ip_compute_csum(const void *buff, int len)
  87 {
  88         return csum_fold(csum_partial(buff, len, 0));
  89 }
  90
  91 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
  92                                      unsigned short len,
  93                                      unsigned short proto,
  94                                      __wsum sum)
  95 {
  96 #ifdef __powerpc64__
  97         unsigned long s = (__force u32)sum;
  98
  99         s += (__force u32)saddr;
 100         s += (__force u32)daddr;
 101         s += proto + len;
 102         s += (s >> 32);
 103         return (__force __wsum) s;
 104 #else
 105     __asm__("\n\
 106         addc %0,%0,%1 \n\
 107         adde %0,%0,%2 \n\
 108         adde %0,%0,%3 \n\
 109         addze %0,%0 \n\
 110         "
 111         : "=r" (sum)
 112         : "r" (daddr), "r"(saddr), "r"(proto + len), "0"(sum));
 113         return sum;
 114 #endif
 115 }
 116 #endif /* __KERNEL__ */
 117 #endif