arch/arm/include/asm/checksum.h

   1 /*
   2  *  arch/arm/include/asm/checksum.h
   3  *
   4  * IP checksum routines
   5  *
   6  * Copyright (C) Original authors of ../asm-i386/checksum.h
   7  * Copyright (C) 1996-1999 Russell King
   8  */
   9 #ifndef __ASM_ARM_CHECKSUM_H
  10 #define __ASM_ARM_CHECKSUM_H
  11
  12 #include <linux/in6.h>
  13
  14 /*
  15  * computes the checksum of a memory block at buff, length len,
  16  * and adds in "sum" (32-bit)
  17  *
  18  * returns a 32-bit number suitable for feeding into itself
  19  * or csum_tcpudp_magic
  20  *
  21  * this function must be called with even lengths, except
  22  * for the last fragment, which may be odd
  23  *
  24  * it's best to have buff aligned on a 32-bit boundary
  25  */
  26 __wsum csum_partial(const void *buff, int len, __wsum sum);
  27
  28 /*
  29  * the same as csum_partial, but copies from src while it
  30  * checksums, and handles user-space pointer exceptions correctly, when needed.
  31  *
  32  * here even more important to align src and dst on a 32-bit (or even
  33  * better 64-bit) boundary
  34  */
  35
  36 __wsum
  37 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);
  38
  39 __wsum
  40 csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr);
  41
  42 /*
  43  *      Fold a partial checksum without adding pseudo headers
  44  */
  45 static inline __sum16 csum_fold(__wsum sum)
  46 {
  47         __asm__(
  48         "add    %0, %1, %1, ror #16     @ csum_fold"
  49         : "=r" (sum)
  50         : "r" (sum)
  51         : "cc");
  52         return (__force __sum16)(~(__force u32)sum >> 16);
  53 }
  54
  55 /*
  56  *      This is a version of ip_compute_csum() optimized for IP headers,
  57  *      which always checksum on 4 octet boundaries.
  58  */
  59 static inline __sum16
  60 ip_fast_csum(const void *iph, unsigned int ihl)
  61 {
  62         unsigned int tmp1;
  63         __wsum sum;
  64
  65         __asm__ __volatile__(
  66         "ldr    %0, [%1], #4            @ ip_fast_csum          \n\
  67         ldr     %3, [%1], #4                                    \n\
  68         sub     %2, %2, #5                                      \n\
  69         adds    %0, %0, %3                                      \n\
  70         ldr     %3, [%1], #4                                    \n\
  71         adcs    %0, %0, %3                                      \n\
  72         ldr     %3, [%1], #4                                    \n\
  73 1:      adcs    %0, %0, %3                                      \n\
  74         ldr     %3, [%1], #4                                    \n\
  75         tst     %2, #15                 @ do this carefully     \n\
  76         subne   %2, %2, #1              @ without destroying    \n\
  77         bne     1b                      @ the carry flag        \n\
  78         adcs    %0, %0, %3                                      \n\
  79         adc     %0, %0, #0"
  80         : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
  81         : "1" (iph), "2" (ihl)
  82         : "cc", "memory");
  83         return csum_fold(sum);
  84 }
  85
  86 static inline __wsum
  87 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
  88                    unsigned short proto, __wsum sum)
  89 {
  90         u32 lenprot = len | proto << 16;
  91         if (__builtin_constant_p(sum) && sum == 0) {
  92                 __asm__(
  93                 "adds   %0, %1, %2      @ csum_tcpudp_nofold0   \n\t"
  94 #ifdef __ARMEB__
  95                 "adcs   %0, %0, %3                              \n\t"
  96 #else
  97                 "adcs   %0, %0, %3, ror #8                      \n\t"
  98 #endif
  99                 "adc    %0, %0, #0"
 100                 : "=&r" (sum)
 101                 : "r" (daddr), "r" (saddr), "r" (lenprot)
 102                 : "cc");
 103         } else {
 104                 __asm__(
 105                 "adds   %0, %1, %2      @ csum_tcpudp_nofold    \n\t"
 106                 "adcs   %0, %0, %3                              \n\t"
 107 #ifdef __ARMEB__
 108                 "adcs   %0, %0, %4                              \n\t"
 109 #else
 110                 "adcs   %0, %0, %4, ror #8                      \n\t"
 111 #endif
 112                 "adc    %0, %0, #0"
 113                 : "=&r"(sum)
 114                 : "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot)
 115                 : "cc");
 116         }
 117         return sum;
 118 }
 119 /*
 120  * computes the checksum of the TCP/UDP pseudo-header
 121  * returns a 16-bit checksum, already complemented
 122  */
 123 static inline __sum16
 124 csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
 125                   unsigned short proto, __wsum sum)
 126 {
 127         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 128 }
 129
 130
 131 /*
 132  * this routine is used for miscellaneous IP-like checksums, mainly
 133  * in icmp.c
 134  */
 135 static inline __sum16
 136 ip_compute_csum(const void *buff, int len)
 137 {
 138         return csum_fold(csum_partial(buff, len, 0));
 139 }
 140
 141 #define _HAVE_ARCH_IPV6_CSUM
 142 extern __wsum
 143 __csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
 144                 __be32 proto, __wsum sum);
 145
 146 static inline __sum16
 147 csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __u32 len,
 148                 unsigned short proto, __wsum sum)
 149 {
 150         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 151                                            htonl(proto), sum));
 152 }
 153 #endif