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         __asm__(
  91         "adds   %0, %1, %2              @ csum_tcpudp_nofold    \n\
  92         adcs    %0, %0, %3                                      \n"
  93 #ifdef __ARMEB__
  94         "adcs   %0, %0, %4                                      \n"
  95 #else
  96         "adcs   %0, %0, %4, lsl #8                              \n"
  97 #endif
  98         "adcs   %0, %0, %5                                      \n\
  99         adc     %0, %0, #0"
 100         : "=&r"(sum)
 101         : "r" (sum), "r" (daddr), "r" (saddr), "r" (len), "Ir" (htons(proto))
 102         : "cc");
 103         return sum;
 104 }
 105 /*
 106  * computes the checksum of the TCP/UDP pseudo-header
 107  * returns a 16-bit checksum, already complemented
 108  */
 109 static inline __sum16
 110 csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
 111                   unsigned short proto, __wsum sum)
 112 {
 113         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 114 }
 115
 116
 117 /*
 118  * this routine is used for miscellaneous IP-like checksums, mainly
 119  * in icmp.c
 120  */
 121 static inline __sum16
 122 ip_compute_csum(const void *buff, int len)
 123 {
 124         return csum_fold(csum_partial(buff, len, 0));
 125 }
 126
 127 #define _HAVE_ARCH_IPV6_CSUM
 128 extern __wsum
 129 __csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
 130                 __be32 proto, __wsum sum);
 131
 132 static inline __sum16
 133 csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __u32 len,
 134                 unsigned short proto, __wsum sum)
 135 {
 136         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 137                                            htonl(proto), sum));
 138 }
 139 #endif