linux/lib/checksum.c
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

205 lines
4.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* IP/TCP/UDP checksumming routines
*
* Authors: Jorge Cwik, <jorge@laser.satlink.net>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Tom May, <ftom@netcom.com>
* Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
* Lots of code moved from tcp.c and ip.c; see those files
* for more names.
*
* 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
* Fixed some nasty bugs, causing some horrible crashes.
* A: At some points, the sum (%0) was used as
* length-counter instead of the length counter
* (%1). Thanks to Roman Hodek for pointing this out.
* B: GCC seems to mess up if one uses too many
* data-registers to hold input values and one tries to
* specify d0 and d1 as scratch registers. Letting gcc
* choose these registers itself solves the problem.
*/
/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access
kills, so most of the assembly has to go. */
#include <linux/export.h>
#include <net/checksum.h>
#include <asm/byteorder.h>
#ifndef do_csum
static inline unsigned short from32to16(unsigned int x)
{
/* add up 16-bit and 16-bit for 16+c bit */
x = (x & 0xffff) + (x >> 16);
/* add up carry.. */
x = (x & 0xffff) + (x >> 16);
return x;
}
static unsigned int do_csum(const unsigned char *buff, int len)
{
int odd;
unsigned int result = 0;
if (len <= 0)
goto out;
odd = 1 & (unsigned long) buff;
if (odd) {
#ifdef __LITTLE_ENDIAN
result += (*buff << 8);
#else
result = *buff;
#endif
len--;
buff++;
}
if (len >= 2) {
if (2 & (unsigned long) buff) {
result += *(unsigned short *) buff;
len -= 2;
buff += 2;
}
if (len >= 4) {
const unsigned char *end = buff + ((unsigned)len & ~3);
unsigned int carry = 0;
do {
unsigned int w = *(unsigned int *) buff;
buff += 4;
result += carry;
result += w;
carry = (w > result);
} while (buff < end);
result += carry;
result = (result & 0xffff) + (result >> 16);
}
if (len & 2) {
result += *(unsigned short *) buff;
buff += 2;
}
}
if (len & 1)
#ifdef __LITTLE_ENDIAN
result += *buff;
#else
result += (*buff << 8);
#endif
result = from32to16(result);
if (odd)
result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
out:
return result;
}
#endif
#ifndef ip_fast_csum
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*/
__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
return (__force __sum16)~do_csum(iph, ihl*4);
}
EXPORT_SYMBOL(ip_fast_csum);
#endif
/*
* computes the checksum of a memory block at buff, length len,
* and adds in "sum" (32-bit)
*
* returns a 32-bit number suitable for feeding into itself
* or csum_tcpudp_magic
*
* this function must be called with even lengths, except
* for the last fragment, which may be odd
*
* it's best to have buff aligned on a 32-bit boundary
*/
__wsum csum_partial(const void *buff, int len, __wsum wsum)
{
unsigned int sum = (__force unsigned int)wsum;
unsigned int result = do_csum(buff, len);
/* add in old sum, and carry.. */
result += sum;
if (sum > result)
result += 1;
return (__force __wsum)result;
}
EXPORT_SYMBOL(csum_partial);
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
__sum16 ip_compute_csum(const void *buff, int len)
{
return (__force __sum16)~do_csum(buff, len);
}
EXPORT_SYMBOL(ip_compute_csum);
/*
* copy from fs while checksumming, otherwise like csum_partial
*/
__wsum
csum_partial_copy_from_user(const void __user *src, void *dst, int len,
__wsum sum, int *csum_err)
{
int missing;
missing = __copy_from_user(dst, src, len);
if (missing) {
memset(dst + len - missing, 0, missing);
*csum_err = -EFAULT;
} else
*csum_err = 0;
return csum_partial(dst, len, sum);
}
EXPORT_SYMBOL(csum_partial_copy_from_user);
/*
* copy from ds while checksumming, otherwise like csum_partial
*/
__wsum
csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
{
memcpy(dst, src, len);
return csum_partial(dst, len, sum);
}
EXPORT_SYMBOL(csum_partial_copy);
#ifndef csum_tcpudp_nofold
static inline u32 from64to32(u64 x)
{
/* add up 32-bit and 32-bit for 32+c bit */
x = (x & 0xffffffff) + (x >> 32);
/* add up carry.. */
x = (x & 0xffffffff) + (x >> 32);
return (u32)x;
}
__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
__u32 len, __u8 proto, __wsum sum)
{
unsigned long long s = (__force u32)sum;
s += (__force u32)saddr;
s += (__force u32)daddr;
#ifdef __BIG_ENDIAN
s += proto + len;
#else
s += (proto + len) << 8;
#endif
return (__force __wsum)from64to32(s);
}
EXPORT_SYMBOL(csum_tcpudp_nofold);
#endif