LXR linux/arch/x86/include/asm/checksum

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_X86_CHECKSUM_64_H
   3#define _ASM_X86_CHECKSUM_64_H
   4
   5/*
   6 * Checksums for x86-64
   7 * Copyright 2002 by Andi Kleen, SuSE Labs
   8 * with some code from asm-x86/checksum.h
   9 */
  10
  11#include <linux/compiler.h>
  12#include <linux/uaccess.h>
  13#include <asm/byteorder.h>
  14
  15/**
  16 * csum_fold - Fold and invert a 32bit checksum.
  17 * sum: 32bit unfolded sum
  18 *
  19 * Fold a 32bit running checksum to 16bit and invert it. This is usually
  20 * the last step before putting a checksum into a packet.
  21 * Make sure not to mix with 64bit checksums.
  22 */
  23static inline __sum16 csum_fold(__wsum sum)
  24{
  25        asm("  addl %1,%0\n"
  26            "  adcl $0xffff,%0"
  27            : "=r" (sum)
  28            : "r" ((__force u32)sum << 16),
  29              "0" ((__force u32)sum & 0xffff0000));
  30        return (__force __sum16)(~(__force u32)sum >> 16);
  31}
  32
  33/*
  34 *      This is a version of ip_compute_csum() optimized for IP headers,
  35 *      which always checksum on 4 octet boundaries.
  36 *
  37 *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  38 *      Arnt Gulbrandsen.
  39 */
  40
  41/**
  42 * ip_fast_csum - Compute the IPv4 header checksum efficiently.
  43 * iph: ipv4 header
  44 * ihl: length of header / 4
  45 */
  46static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  47{
  48        unsigned int sum;
  49
  50        asm("  movl (%1), %0\n"
  51            "  subl $4, %2\n"
  52            "  jbe 2f\n"
  53            "  addl 4(%1), %0\n"
  54            "  adcl 8(%1), %0\n"
  55            "  adcl 12(%1), %0\n"
  56            "1: adcl 16(%1), %0\n"
  57            "  lea 4(%1), %1\n"
  58            "  decl %2\n"
  59            "  jne      1b\n"
  60            "  adcl $0, %0\n"
  61            "  movl %0, %2\n"
  62            "  shrl $16, %0\n"
  63            "  addw %w2, %w0\n"
  64            "  adcl $0, %0\n"
  65            "  notl %0\n"
  66            "2:"
  67        /* Since the input registers which are loaded with iph and ihl
  68           are modified, we must also specify them as outputs, or gcc
  69           will assume they contain their original values. */
  70            : "=r" (sum), "=r" (iph), "=r" (ihl)
  71            : "1" (iph), "2" (ihl)
  72            : "memory");
  73        return (__force __sum16)sum;
  74}
  75
  76/**
  77 * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
  78 * @saddr: source address
  79 * @daddr: destination address
  80 * @len: length of packet
  81 * @proto: ip protocol of packet
  82 * @sum: initial sum to be added in (32bit unfolded)
  83 *
  84 * Returns the pseudo header checksum the input data. Result is
  85 * 32bit unfolded.
  86 */
  87static inline __wsum
  88csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
  89                   __u8 proto, __wsum sum)
  90{
  91        asm("  addl %1, %0\n"
  92            "  adcl %2, %0\n"
  93            "  adcl %3, %0\n"
  94            "  adcl $0, %0\n"
  95            : "=r" (sum)
  96            : "g" (daddr), "g" (saddr),
  97              "g" ((len + proto)<<8), "0" (sum));
  98        return sum;
  99}
 100
 101
 102/**
 103 * csum_tcpup_magic - Compute an IPv4 pseudo header checksum.
 104 * @saddr: source address
 105 * @daddr: destination address
 106 * @len: length of packet
 107 * @proto: ip protocol of packet
 108 * @sum: initial sum to be added in (32bit unfolded)
 109 *
 110 * Returns the 16bit pseudo header checksum the input data already
 111 * complemented and ready to be filled in.
 112 */
 113static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 114                                        __u32 len, __u8 proto,
 115                                        __wsum sum)
 116{
 117        return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 118}
 119
 120/**
 121 * csum_partial - Compute an internet checksum.
 122 * @buff: buffer to be checksummed
 123 * @len: length of buffer.
 124 * @sum: initial sum to be added in (32bit unfolded)
 125 *
 126 * Returns the 32bit unfolded internet checksum of the buffer.
 127 * Before filling it in it needs to be csum_fold()'ed.
 128 * buff should be aligned to a 64bit boundary if possible.
 129 */
 130extern __wsum csum_partial(const void *buff, int len, __wsum sum);
 131
 132/* Do not call this directly. Use the wrappers below */
 133extern __visible __wsum csum_partial_copy_generic(const void *src, void *dst, int len);
 134
 135extern __wsum csum_and_copy_from_user(const void __user *src, void *dst, int len);
 136extern __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len);
 137extern __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len);
 138
 139/**
 140 * ip_compute_csum - Compute an 16bit IP checksum.
 141 * @buff: buffer address.
 142 * @len: length of buffer.
 143 *
 144 * Returns the 16bit folded/inverted checksum of the passed buffer.
 145 * Ready to fill in.
 146 */
 147extern __sum16 ip_compute_csum(const void *buff, int len);
 148
 149/**
 150 * csum_ipv6_magic - Compute checksum of an IPv6 pseudo header.
 151 * @saddr: source address
 152 * @daddr: destination address
 153 * @len: length of packet
 154 * @proto: protocol of packet
 155 * @sum: initial sum (32bit unfolded) to be added in
 156 *
 157 * Computes an IPv6 pseudo header checksum. This sum is added the checksum
 158 * into UDP/TCP packets and contains some link layer information.
 159 * Returns the unfolded 32bit checksum.
 160 */
 161
 162struct in6_addr;
 163
 164#define _HAVE_ARCH_IPV6_CSUM 1
 165extern __sum16
 166csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
 167                __u32 len, __u8 proto, __wsum sum);
 168
 169static inline unsigned add32_with_carry(unsigned a, unsigned b)
 170{
 171        asm("addl %2,%0\n\t"
 172            "adcl $0,%0"
 173            : "=r" (a)
 174            : "0" (a), "rm" (b));
 175        return a;
 176}
 177
 178#define HAVE_ARCH_CSUM_ADD
 179static inline __wsum csum_add(__wsum csum, __wsum addend)
 180{
 181        return (__force __wsum)add32_with_carry((__force unsigned)csum,
 182                                                (__force unsigned)addend);
 183}
 184
 185#endif /* _ASM_X86_CHECKSUM_64_H */
 186