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 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int 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 unsigned int
  37 csum_partial_copy_nocheck(const char *src, char *dst, int len, int sum);
  38
  39 unsigned int
  40 csum_partial_copy_from_user(const char __user *src, char *dst, int len, int sum, int *err_ptr);
  41
  42 /*
  43  * This is the old (and unsafe) way of doing checksums, a warning message will
  44  * be printed if it is used and an exception occurs.
  45  *
  46  * this functions should go away after some time.
  47  */
  48 #define csum_partial_copy(src,dst,len,sum)      csum_partial_copy_nocheck(src,dst,len,sum)
  49
  50 /*
  51  *      This is a version of ip_compute_csum() optimized for IP headers,
  52  *      which always checksum on 4 octet boundaries.
  53  */
  54 static inline unsigned short
  55 ip_fast_csum(unsigned char * iph, unsigned int ihl)
  56 {
  57         unsigned int sum, tmp1;
  58
  59         __asm__ __volatile__(
  60         "ldr    %0, [%1], #4            @ ip_fast_csum          \n\
  61         ldr     %3, [%1], #4                                    \n\
  62         sub     %2, %2, #5                                      \n\
  63         adds    %0, %0, %3                                      \n\
  64         ldr     %3, [%1], #4                                    \n\
  65         adcs    %0, %0, %3                                      \n\
  66         ldr     %3, [%1], #4                                    \n\
  67 1:      adcs    %0, %0, %3                                      \n\
  68         ldr     %3, [%1], #4                                    \n\
  69         tst     %2, #15                 @ do this carefully     \n\
  70         subne   %2, %2, #1              @ without destroying    \n\
  71         bne     1b                      @ the carry flag        \n\
  72         adcs    %0, %0, %3                                      \n\
  73         adc     %0, %0, #0                                      \n\
  74         adds    %0, %0, %0, lsl #16                             \n\
  75         addcs   %0, %0, #0x10000                                \n\
  76         mvn     %0, %0                                          \n\
  77         mov     %0, %0, lsr #16"
  78         : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
  79         : "1" (iph), "2" (ihl)
  80         : "cc", "memory");
  81         return sum;
  82 }
  83
  84 /*
  85  *      Fold a partial checksum without adding pseudo headers
  86  */
  87 static inline unsigned int
  88 csum_fold(unsigned int sum)
  89 {
  90         __asm__(
  91         "adds   %0, %1, %1, lsl #16     @ csum_fold             \n\
  92         addcs   %0, %0, #0x10000"
  93         : "=r" (sum)
  94         : "r" (sum)
  95         : "cc");
  96         return (~sum) >> 16;
  97 }
  98
  99 static inline unsigned int
 100 csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
 101                    unsigned int proto, unsigned int sum)
 102 {
 103         __asm__(
 104         "adds   %0, %1, %2              @ csum_tcpudp_nofold    \n\
 105         adcs    %0, %0, %3                                      \n\
 106         adcs    %0, %0, %4                                      \n\
 107         adcs    %0, %0, %5                                      \n\
 108         adc     %0, %0, #0"
 109         : "=&r"(sum)
 110         : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)), "Ir" (ntohs(proto))
 111         : "cc");
 112         return sum;
 113 }
 114 /*
 115  * computes the checksum of the TCP/UDP pseudo-header
 116  * returns a 16-bit checksum, already complemented
 117  */
 118 static inline unsigned short int
 119 csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len,
 120                   unsigned int proto, unsigned int sum)
 121 {
 122         __asm__(
 123         "adds   %0, %1, %2              @ csum_tcpudp_magic     \n\
 124         adcs    %0, %0, %3                                      \n\
 125         adcs    %0, %0, %4                                      \n\
 126         adcs    %0, %0, %5                                      \n\
 127         adc     %0, %0, #0                                      \n\
 128         adds    %0, %0, %0, lsl #16                             \n\
 129         addcs   %0, %0, #0x10000                                \n\
 130         mvn     %0, %0"
 131         : "=&r"(sum)
 132         : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)), "Ir" (ntohs(proto))
 133         : "cc");
 134         return sum >> 16;
 135 }
 136
 137
 138 /*
 139  * this routine is used for miscellaneous IP-like checksums, mainly
 140  * in icmp.c
 141  */
 142 static inline unsigned short
 143 ip_compute_csum(unsigned char * buff, int len)
 144 {
 145         return csum_fold(csum_partial(buff, len, 0));
 146 }
 147
 148 #define _HAVE_ARCH_IPV6_CSUM
 149 extern unsigned long
 150 __csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
 151                 __u32 proto, unsigned int sum);
 152
 153 static inline unsigned short int
 154 csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
 155                 unsigned short proto, unsigned int sum)
 156 {
 157         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 158                                            htonl(proto), sum));
 159 }
 160 #endif