LXR linux/arch/x86/um/asm/checksum.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __UM_CHECKSUM_H
   3#define __UM_CHECKSUM_H
   4
   5#include <linux/string.h>
   6#include <linux/in6.h>
   7#include <linux/uaccess.h>
   8
   9/*
  10 * computes the checksum of a memory block at buff, length len,
  11 * and adds in "sum" (32-bit)
  12 *
  13 * returns a 32-bit number suitable for feeding into itself
  14 * or csum_tcpudp_magic
  15 *
  16 * this function must be called with even lengths, except
  17 * for the last fragment, which may be odd
  18 *
  19 * it's best to have buff aligned on a 32-bit boundary
  20 */
  21extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  22
  23/*
  24 *      Note: when you get a NULL pointer exception here this means someone
  25 *      passed in an incorrect kernel address to one of these functions.
  26 *
  27 *      If you use these functions directly please don't forget the
  28 *      access_ok().
  29 */
  30
  31static __inline__
  32__wsum csum_partial_copy_nocheck(const void *src, void *dst,
  33                                       int len, __wsum sum)
  34{
  35        memcpy(dst, src, len);
  36        return csum_partial(dst, len, sum);
  37}
  38
  39/*
  40 * the same as csum_partial, but copies from src while it
  41 * checksums, and handles user-space pointer exceptions correctly, when needed.
  42 *
  43 * here even more important to align src and dst on a 32-bit (or even
  44 * better 64-bit) boundary
  45 */
  46
  47static __inline__
  48__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  49                                         int len, __wsum sum, int *err_ptr)
  50{
  51        if (copy_from_user(dst, src, len)) {
  52                *err_ptr = -EFAULT;
  53                return (__force __wsum)-1;
  54        }
  55
  56        return csum_partial(dst, len, sum);
  57}
  58
  59/**
  60 * csum_fold - Fold and invert a 32bit checksum.
  61 * sum: 32bit unfolded sum
  62 *
  63 * Fold a 32bit running checksum to 16bit and invert it. This is usually
  64 * the last step before putting a checksum into a packet.
  65 * Make sure not to mix with 64bit checksums.
  66 */
  67static inline __sum16 csum_fold(__wsum sum)
  68{
  69        __asm__(
  70                "  addl %1,%0\n"
  71                "  adcl $0xffff,%0"
  72                : "=r" (sum)
  73                : "r" ((__force u32)sum << 16),
  74                  "0" ((__force u32)sum & 0xffff0000)
  75        );
  76        return (__force __sum16)(~(__force u32)sum >> 16);
  77}
  78
  79/**
  80 * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
  81 * @saddr: source address
  82 * @daddr: destination address
  83 * @len: length of packet
  84 * @proto: ip protocol of packet
  85 * @sum: initial sum to be added in (32bit unfolded)
  86 *
  87 * Returns the pseudo header checksum the input data. Result is
  88 * 32bit unfolded.
  89 */
  90static inline __wsum
  91csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
  92                  __u8 proto, __wsum sum)
  93{
  94        asm("  addl %1, %0\n"
  95            "  adcl %2, %0\n"
  96            "  adcl %3, %0\n"
  97            "  adcl $0, %0\n"
  98                : "=r" (sum)
  99            : "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum));
 100        return sum;
 101}
 102
 103/*
 104 * computes the checksum of the TCP/UDP pseudo-header
 105 * returns a 16-bit checksum, already complemented
 106 */
 107static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 108                                        __u32 len, __u8 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