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 /*
  13  * computes the checksum of a memory block at buff, length len,
  14  * and adds in "sum" (32-bit)
  15  *
  16  * returns a 32-bit number suitable for feeding into itself
  17  * or csum_tcpudp_magic
  18  *
  19  * this function must be called with even lengths, except
  20  * for the last fragment, which may be odd
  21  *
  22  * it's best to have buff aligned on a 32-bit boundary
  23  */
  24 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
  25
  26 /*
  27  * the same as csum_partial, but copies from src while it
  28  * checksums, and handles user-space pointer exceptions correctly, when needed.
  29  *
  30  * here even more important to align src and dst on a 32-bit (or even
  31  * better 64-bit) boundary
  32  */
  33
  34 unsigned int
  35 csum_partial_copy_nocheck(const char *src, char *dst, int len, int sum);
  36
  37 unsigned int
  38 csum_partial_copy_from_user(const char *src, char *dst, int len, int sum, int *err_ptr);
  39
  40 /*
  41  * These are the old (and unsafe) way of doing checksums, a warning message will be
  42  * printed if they are used and an exception occurs.
  43  *
  44  * these functions should go away after some time.
  45  */
  46 #define csum_partial_copy(src,dst,len,sum)      csum_partial_copy_nocheck(src,dst,len,sum)
  47
  48 /*
  49  *      This is a version of ip_compute_csum() optimized for IP headers,
  50  *      which always checksum on 4 octet boundaries.
  51  */
  52 static inline unsigned short
  53 ip_fast_csum(unsigned char * iph, unsigned int ihl)
  54 {
  55         unsigned int sum, tmp1;
  56
  57         __asm__ __volatile__(
  58         "ldr    %0, [%1], #4            @ ip_fast_csum
  59         ldr     %3, [%1], #4
  60         sub     %2, %2, #5
  61         adds    %0, %0, %3
  62         ldr     %3, [%1], #4
  63         adcs    %0, %0, %3
  64         ldr     %3, [%1], #4
  65         adcs    %0, %0, %3
  66 1:      ldr     %3, [%1], #4
  67         adcs    %0, %0, %3
  68         tst     %2, #15
  69         subne   %2, %2, #1
  70         bne     1b
  71         adc     %0, %0, #0
  72         adds    %0, %0, %0, lsl #16
  73         addcs   %0, %0, #0x10000
  74         mvn     %0, %0
  75         mov     %0, %0, lsr #16
  76         "
  77         : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
  78         : "1" (iph), "2" (ihl)
  79         : "cc");
  80         return sum;
  81 }
  82
  83 /*
  84  *      Fold a partial checksum without adding pseudo headers
  85  */
  86 static inline unsigned int
  87 csum_fold(unsigned int sum)
  88 {
  89         __asm__(
  90         "adds   %0, %1, %1, lsl #16     @ csum_fold
  91         addcs   %0, %0, #0x10000"
  92         : "=r" (sum)
  93         : "r" (sum)
  94         : "cc");
  95         return (~sum) >> 16;
  96 }
  97
  98 static inline unsigned int
  99 csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
 100                    unsigned int proto, unsigned int sum)
 101 {
 102         __asm__(
 103         "adds   %0, %1, %2              @ csum_tcpudp_nofold
 104         adcs    %0, %0, %3
 105         adcs    %0, %0, %4
 106         adcs    %0, %0, %5
 107         adc     %0, %0, #0"
 108         : "=&r"(sum)
 109         : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len) << 16), "Ir" (proto << 8)
 110         : "cc");
 111         return sum;
 112 }
 113 /*
 114  * computes the checksum of the TCP/UDP pseudo-header
 115  * returns a 16-bit checksum, already complemented
 116  */
 117 static inline unsigned short int
 118 csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len,
 119                   unsigned int proto, unsigned int sum)
 120 {
 121         __asm__(
 122         "adds   %0, %1, %2              @ csum_tcpudp_magic
 123         adcs    %0, %0, %3
 124         adcs    %0, %0, %4
 125         adcs    %0, %0, %5
 126         adc     %0, %0, #0
 127         adds    %0, %0, %0, lsl #16
 128         addcs   %0, %0, #0x10000
 129         mvn     %0, %0"
 130         : "=&r"(sum)
 131         : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)), "Ir" (proto << 8)
 132         : "cc");
 133         return 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 unsigned short
 142 ip_compute_csum(unsigned char * buff, int len)
 143 {
 144         return csum_fold(csum_partial(buff, len, 0));
 145 }
 146
 147 #define _HAVE_ARCH_IPV6_CSUM
 148 extern unsigned long
 149 __csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
 150                 __u32 proto, unsigned int sum);
 151
 152 extern __inline__ unsigned short int
 153 csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
 154                 unsigned short proto, unsigned int sum)
 155 {
 156         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 157                                            htonl(proto), sum));
 158 }
 159 #endif