LXR linux/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#include <linux/uaccess.h>
   7
   8/*
   9 * computes the checksum of a memory block at buff, length len,
  10 * and adds in "sum" (32-bit)
  11 *
  12 * returns a 32-bit number suitable for feeding into itself
  13 * or csum_tcpudp_magic
  14 *
  15 * this function must be called with even lengths, except
  16 * for the last fragment, which may be odd
  17 *
  18 * it's best to have buff aligned on a 32-bit boundary
  19 */
  20extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  21
  22/*
  23 *      Note: when you get a NULL pointer exception here this means someone
  24 *      passed in an incorrect kernel address to one of these functions.
  25 *
  26 *      If you use these functions directly please don't forget the
  27 *      access_ok().
  28 */
  29
  30static __inline__
  31__wsum csum_partial_copy_nocheck(const void *src, void *dst,
  32                                       int len, __wsum sum)
  33{
  34        memcpy(dst, src, len);
  35        return csum_partial(dst, len, sum);
  36}
  37
  38/*
  39 * the same as csum_partial, but copies from src while it
  40 * checksums, and handles user-space pointer exceptions correctly, when needed.
  41 *
  42 * here even more important to align src and dst on a 32-bit (or even
  43 * better 64-bit) boundary
  44 */
  45
  46static __inline__
  47__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  48                                         int len, __wsum sum, int *err_ptr)
  49{
  50        if (copy_from_user(dst, src, len)) {
  51                *err_ptr = -EFAULT;
  52                return (__force __wsum)-1;
  53        }
  54
  55        return csum_partial(dst, len, sum);
  56}
  57
  58/**
  59 * csum_fold - Fold and invert a 32bit checksum.
  60 * sum: 32bit unfolded sum
  61 *
  62 * Fold a 32bit running checksum to 16bit and invert it. This is usually
  63 * the last step before putting a checksum into a packet.
  64 * Make sure not to mix with 64bit checksums.
  65 */
  66static inline __sum16 csum_fold(__wsum sum)
  67{
  68        __asm__(
  69                "  addl %1,%0\n"
  70                "  adcl $0xffff,%0"
  71                : "=r" (sum)
  72                : "r" ((__force u32)sum << 16),
  73                  "0" ((__force u32)sum & 0xffff0000)
  74        );
  75        return (__force __sum16)(~(__force u32)sum >> 16);
  76}
  77
  78/**
  79 * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
  80 * @saddr: source address
  81 * @daddr: destination address
  82 * @len: length of packet
  83 * @proto: ip protocol of packet
  84 * @sum: initial sum to be added in (32bit unfolded)
  85 *
  86 * Returns the pseudo header checksum the input data. Result is
  87 * 32bit unfolded.
  88 */
  89static inline __wsum
  90csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
  91                   unsigned short proto, __wsum sum)
  92{
  93        asm("  addl %1, %0\n"
  94            "  adcl %2, %0\n"
  95            "  adcl %3, %0\n"
  96            "  adcl $0, %0\n"
  97                : "=r" (sum)
  98            : "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum));
  99        return sum;
 100}
 101
 102/*
 103 * computes the checksum of the TCP/UDP pseudo-header
 104 * returns a 16-bit checksum, already complemented
 105 */
 106static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 107                                           unsigned short len,
 108                                           unsigned short proto,
 109                                           __wsum sum)
 110{
 111        return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
 112}
 113
 114/**
 115 * ip_fast_csum - Compute the IPv4 header checksum efficiently.
 116 * iph: ipv4 header
 117 * ihl: length of header / 4
 118 */
 119static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
 120{
 121        unsigned int sum;
 122
 123        asm(    "  movl (%1), %0\n"
 124                "  subl $4, %2\n"
 125                "  jbe 2f\n"
 126                "  addl 4(%1), %0\n"
 127                "  adcl 8(%1), %0\n"
 128                "  adcl 12(%1), %0\n"
 129                "1: adcl 16(%1), %0\n"
 130                "  lea 4(%1), %1\n"
 131                "  decl %2\n"
 132                "  jne  1b\n"
 133                "  adcl $0, %0\n"
 134                "  movl %0, %2\n"
 135                "  shrl $16, %0\n"
 136                "  addw %w2, %w0\n"
 137                "  adcl $0, %0\n"
 138                "  notl %0\n"
 139                "2:"
 140        /* Since the input registers which are loaded with iph and ipl
 141           are modified, we must also specify them as outputs, or gcc
 142           will assume they contain their original values. */
 143        : "=r" (sum), "=r" (iph), "=r" (ihl)
 144        : "1" (iph), "2" (ihl)
 145        : "memory");
 146        return (__force __sum16)sum;
 147}
 148
 149#ifdef CONFIG_X86_32
 150# include "checksum_32.h"
 151#else
 152# include "checksum_64.h"
 153#endif
 154
 155#endif
 156