LXR linux/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
  37csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);
  38
  39__wsum
  40csum_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 */
  45static 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 */
  59static inline __sum16
  60ip_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\
  731:      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
  86static inline __wsum
  87csum_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 */
 123static inline __sum16
 124csum_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 */
 135static inline __sum16
 136ip_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
 142extern __wsum
 143__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
 144                __be32 proto, __wsum sum);
 145
 146static inline __sum16
 147csum_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
 154