include/asm-arm/checksum.h

   1 /*
   2  *  linux/include/asm-arm/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  *      This is a version of ip_compute_csum() optimized for IP headers,
  44  *      which always checksum on 4 octet boundaries.
  45  */
  46 static inline __sum16
  47 ip_fast_csum(const void *iph, unsigned int ihl)
  48 {
  49         unsigned int sum, tmp1;
  50
  51         __asm__ __volatile__(
  52         "ldr    %0, [%1], #4            @ ip_fast_csum          \n\
  53         ldr     %3, [%1], #4                                    \n\
  54         sub     %2, %2, #5                                      \n\
  55         adds    %0, %0, %3                                      \n\
  56         ldr     %3, [%1], #4                                    \n\
  57         adcs    %0, %0, %3                                      \n\
  58         ldr     %3, [%1], #4                                    \n\
  59 1:      adcs    %0, %0, %3                                      \n\
  60         ldr     %3, [%1], #4                                    \n\
  61         tst     %2, #15                 @ do this carefully     \n\
  62         subne   %2, %2, #1              @ without destroying    \n\
  63         bne     1b                      @ the carry flag        \n\
  64         adcs    %0, %0, %3                                      \n\
  65         adc     %0, %0, #0                                      \n\
  66         adds    %0, %0, %0, lsl #16                             \n\
  67         addcs   %0, %0, #0x10000                                \n\
  68         mvn     %0, %0                                          \n\
  69         mov     %0, %0, lsr #16"
  70         : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
  71         : "1" (iph), "2" (ihl)
  72         : "cc", "memory");
  73         return (__force __sum16)sum;
  74 }
  75
  76 /*
  77  *      Fold a partial checksum without adding pseudo headers
  78  */
  79 static inline __sum16 csum_fold(__wsum sum)
  80 {
  81         __asm__(
  82         "adds   %0, %1, %1, lsl #16     @ csum_fold             \n\
  83         addcs   %0, %0, #0x10000"
  84         : "=r" (sum)
  85         : "r" (sum)
  86         : "cc");
  87         return (__force __sum16)(~(__force u32)sum >> 16);
  88 }
  89
  90 static inline __wsum
  91 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
  92                    unsigned short proto, __wsum sum)
  93 {
  94         __asm__(
  95         "adds   %0, %1, %2              @ csum_tcpudp_nofold    \n\
  96         adcs    %0, %0, %3                                      \n"
  97 #ifdef __ARMEB__
  98         "adcs   %0, %0, %4                                      \n"
  99 #else
 100         "adcs   %0, %0, %4, lsl #8                              \n"
 101 #endif
 102         "adcs   %0, %0, %5                                      \n\
 103         adc     %0, %0, #0"
 104         : "=&r"(sum)
 105         : "r" (sum), "r" (daddr), "r" (saddr), "r" (len), "Ir" (htons(proto))
 106         : "cc");
 107         return sum;
 108 }
 109 /*
 110  * computes the checksum of the TCP/UDP pseudo-header
 111  * returns a 16-bit checksum, already complemented
 112  */
 113 static inline __sum16
 114 csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
 115                   unsigned short proto, __wsum sum)
 116 {
 117         __asm__(
 118         "adds   %0, %1, %2              @ csum_tcpudp_magic     \n\
 119         adcs    %0, %0, %3                                      \n"
 120 #ifdef __ARMEB__
 121         "adcs   %0, %0, %4                                      \n"
 122 #else
 123         "adcs   %0, %0, %4, lsl #8                              \n"
 124 #endif
 125         "adcs   %0, %0, %5                                      \n\
 126         adc     %0, %0, #0                                      \n\
 127         adds    %0, %0, %0, lsl #16                             \n\
 128         addcs   %0, %0, #0x10000                                \n\
 129         mvn     %0, %0"
 130         : "=&r"(sum)
 131         : "r" (sum), "r" (daddr), "r" (saddr), "r" (len), "Ir" (htons(proto))
 132         : "cc");
 133         return (__force __sum16)((__force u32)sum >> 16);
 134 }
 135
 136
 137 /*
 138  * this routine is used for miscellaneous IP-like checksums, mainly
 139  * in icmp.c
 140  */
 141 static inline __sum16
 142 ip_compute_csum(const void *buff, int len)
 143 {
 144         return csum_fold(csum_partial(buff, len, 0));
 145 }
 146
 147 #define _HAVE_ARCH_IPV6_CSUM
 148 extern __wsum
 149 __csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
 150                 __be32 proto, __wsum sum);
 151
 152 static inline __sum16
 153 csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __u32 len,
 154                 unsigned short proto, __wsum sum)
 155 {
 156         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 157                                            htonl(proto), sum));
 158 }
 159 #endif