arch/x86/um/asm/checksum.h

   1 #ifndef __UM_CHECKSUM_H
   2 #define __UM_CHECKSUM_H
   3
   4 #include <linux/string.h>
   5 #include <linux/in6.h>
   6
   7 /*
   8  * computes the checksum of a memory block at buff, length len,
   9  * and adds in "sum" (32-bit)
  10  *
  11  * returns a 32-bit number suitable for feeding into itself
  12  * or csum_tcpudp_magic
  13  *
  14  * this function must be called with even lengths, except
  15  * for the last fragment, which may be odd
  16  *
  17  * it's best to have buff aligned on a 32-bit boundary
  18  */
  19 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  20
  21 /*
  22  *      Note: when you get a NULL pointer exception here this means someone
  23  *      passed in an incorrect kernel address to one of these functions.
  24  *
  25  *      If you use these functions directly please don't forget the
  26  *      access_ok().
  27  */
  28
  29 static __inline__
  30 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
  31                                        int len, __wsum sum)
  32 {
  33         memcpy(dst, src, len);
  34         return csum_partial(dst, len, sum);
  35 }
  36
  37 /*
  38  * the same as csum_partial, but copies from src while it
  39  * checksums, and handles user-space pointer exceptions correctly, when needed.
  40  *
  41  * here even more important to align src and dst on a 32-bit (or even
  42  * better 64-bit) boundary
  43  */
  44
  45 static __inline__
  46 __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  47                                          int len, __wsum sum, int *err_ptr)
  48 {
  49         if (copy_from_user(dst, src, len)) {
  50                 *err_ptr = -EFAULT;
  51                 return (__force __wsum)-1;
  52         }
  53
  54         return csum_partial(dst, len, sum);
  55 }
  56
  57 /**
  58  * csum_fold - Fold and invert a 32bit checksum.
  59  * sum: 32bit unfolded sum
  60  *
  61  * Fold a 32bit running checksum to 16bit and invert it. This is usually
  62  * the last step before putting a checksum into a packet.
  63  * Make sure not to mix with 64bit checksums.
  64  */
  65 static inline __sum16 csum_fold(__wsum sum)
  66 {
  67         __asm__(
  68                 "  addl %1,%0\n"
  69                 "  adcl $0xffff,%0"
  70                 : "=r" (sum)
  71                 : "r" ((__force u32)sum << 16),
  72                   "0" ((__force u32)sum & 0xffff0000)
  73         );
  74         return (__force __sum16)(~(__force u32)sum >> 16);
  75 }
  76
  77 /**
  78  * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
  79  * @saddr: source address
  80  * @daddr: destination address
  81  * @len: length of packet
  82  * @proto: ip protocol of packet
  83  * @sum: initial sum to be added in (32bit unfolded)
  84  *
  85  * Returns the pseudo header checksum the input data. Result is
  86  * 32bit unfolded.
  87  */
  88 static inline __wsum
  89 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
  90                    unsigned short proto, __wsum sum)
  91 {
  92         asm("  addl %1, %0\n"
  93             "  adcl %2, %0\n"
  94             "  adcl %3, %0\n"
  95             "  adcl $0, %0\n"
  96                 : "=r" (sum)
  97             : "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum));
  98         return sum;
  99 }
 100
 101 /*
 102  * computes the checksum of the TCP/UDP pseudo-header
 103  * returns a 16-bit checksum, already complemented
 104  */
 105 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 106                                            unsigned short len,
 107                                            unsigned short proto,
 108                                            __wsum sum)
 109 {
 110         return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 111 }
 112
 113 /**
 114  * ip_fast_csum - Compute the IPv4 header checksum efficiently.
 115  * iph: ipv4 header
 116  * ihl: length of header / 4
 117  */
 118 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
 119 {
 120         unsigned int sum;
 121
 122         asm(    "  movl (%1), %0\n"
 123                 "  subl $4, %2\n"
 124                 "  jbe 2f\n"
 125                 "  addl 4(%1), %0\n"
 126                 "  adcl 8(%1), %0\n"
 127                 "  adcl 12(%1), %0\n"
 128                 "1: adcl 16(%1), %0\n"
 129                 "  lea 4(%1), %1\n"
 130                 "  decl %2\n"
 131                 "  jne  1b\n"
 132                 "  adcl $0, %0\n"
 133                 "  movl %0, %2\n"
 134                 "  shrl $16, %0\n"
 135                 "  addw %w2, %w0\n"
 136                 "  adcl $0, %0\n"
 137                 "  notl %0\n"
 138                 "2:"
 139         /* Since the input registers which are loaded with iph and ipl
 140            are modified, we must also specify them as outputs, or gcc
 141            will assume they contain their original values. */
 142         : "=r" (sum), "=r" (iph), "=r" (ihl)
 143         : "1" (iph), "2" (ihl)
 144         : "memory");
 145         return (__force __sum16)sum;
 146 }
 147
 148 #ifdef CONFIG_X86_32
 149 # include "checksum_32.h"
 150 #else
 151 # include "checksum_64.h"
 152 #endif
 153
 154 #endif