arch/um/include/sysdep-x86_64/checksum.h

   1 /*
   2  * Licensed under the GPL
   3  */
   4
   5 #ifndef __UM_SYSDEP_CHECKSUM_H
   6 #define __UM_SYSDEP_CHECKSUM_H
   7
   8 #include "linux/string.h"
   9 #include "linux/in6.h"
  10 #include "asm/uaccess.h"
  11
  12 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  13
  14 /*
  15  *      Note: when you get a NULL pointer exception here this means someone
  16  *      passed in an incorrect kernel address to one of these functions.
  17  *
  18  *      If you use these functions directly please don't forget the
  19  *      access_ok().
  20  */
  21
  22 static __inline__
  23 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
  24                                        int len, __wsum sum)
  25 {
  26         memcpy(dst, src, len);
  27         return(csum_partial(dst, len, sum));
  28 }
  29
  30 static __inline__
  31 __wsum csum_partial_copy_from_user(const void __user *src,
  32                                          void *dst, int len, __wsum sum,
  33                                          int *err_ptr)
  34 {
  35         if (copy_from_user(dst, src, len)) {
  36                 *err_ptr = -EFAULT;
  37                 return (__force __wsum)-1;
  38         }
  39         return csum_partial(dst, len, sum);
  40 }
  41
  42 /**
  43  * csum_fold - Fold and invert a 32bit checksum.
  44  * sum: 32bit unfolded sum
  45  *
  46  * Fold a 32bit running checksum to 16bit and invert it. This is usually
  47  * the last step before putting a checksum into a packet.
  48  * Make sure not to mix with 64bit checksums.
  49  */
  50 static inline __sum16 csum_fold(__wsum sum)
  51 {
  52         __asm__(
  53                 "  addl %1,%0\n"
  54                 "  adcl $0xffff,%0"
  55                 : "=r" (sum)
  56                 : "r" ((__force u32)sum << 16),
  57                   "0" ((__force u32)sum & 0xffff0000)
  58         );
  59         return (__force __sum16)(~(__force u32)sum >> 16);
  60 }
  61
  62 /**
  63  * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
  64  * @saddr: source address
  65  * @daddr: destination address
  66  * @len: length of packet
  67  * @proto: ip protocol of packet
  68  * @sum: initial sum to be added in (32bit unfolded)
  69  *
  70  * Returns the pseudo header checksum the input data. Result is
  71  * 32bit unfolded.
  72  */
  73 static inline __wsum
  74 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
  75                    unsigned short proto, __wsum sum)
  76 {
  77         asm("  addl %1, %0\n"
  78             "  adcl %2, %0\n"
  79             "  adcl %3, %0\n"
  80             "  adcl $0, %0\n"
  81                 : "=r" (sum)
  82             : "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum));
  83         return sum;
  84 }
  85
  86 /*
  87  * computes the checksum of the TCP/UDP pseudo-header
  88  * returns a 16-bit checksum, already complemented
  89  */
  90 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
  91                                            unsigned short len,
  92                                            unsigned short proto,
  93                                            __wsum sum)
  94 {
  95         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
  96 }
  97
  98 /**
  99  * ip_fast_csum - Compute the IPv4 header checksum efficiently.
 100  * iph: ipv4 header
 101  * ihl: length of header / 4
 102  */
 103 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
 104 {
 105         unsigned int sum;
 106
 107         asm(    "  movl (%1), %0\n"
 108                 "  subl $4, %2\n"
 109                 "  jbe 2f\n"
 110                 "  addl 4(%1), %0\n"
 111                 "  adcl 8(%1), %0\n"
 112                 "  adcl 12(%1), %0\n"
 113                 "1: adcl 16(%1), %0\n"
 114                 "  lea 4(%1), %1\n"
 115                 "  decl %2\n"
 116                 "  jne  1b\n"
 117                 "  adcl $0, %0\n"
 118                 "  movl %0, %2\n"
 119                 "  shrl $16, %0\n"
 120                 "  addw %w2, %w0\n"
 121                 "  adcl $0, %0\n"
 122                 "  notl %0\n"
 123                 "2:"
 124         /* Since the input registers which are loaded with iph and ipl
 125            are modified, we must also specify them as outputs, or gcc
 126            will assume they contain their original values. */
 127         : "=r" (sum), "=r" (iph), "=r" (ihl)
 128         : "1" (iph), "2" (ihl)
 129         : "memory");
 130         return (__force __sum16)sum;
 131 }
 132
 133 static inline unsigned add32_with_carry(unsigned a, unsigned b)
 134 {
 135         asm("addl %2,%0\n\t"
 136             "adcl $0,%0"
 137             : "=r" (a)
 138             : "0" (a), "r" (b));
 139         return a;
 140 }
 141
 142 extern __sum16 ip_compute_csum(const void *buff, int len);
 143
 144 #endif