cregit-Linux how code gets into the kernel

Release 4.18 lib/checksum.c

Directory: lib
/*
 *
 * 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.
 *
 *              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.
 */

/* 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; }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann45100.00%2100.00%
Total45100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann26790.82%480.00%
Ian Abbott279.18%120.00%
Total294100.00%5100.00%

#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); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann29100.00%1100.00%
Total29100.00%1100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann60100.00%1100.00%
Total60100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann26100.00%1100.00%
Total26100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann80100.00%1100.00%
Total80100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann39100.00%1100.00%
Total39100.00%1100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Karl Beldan46100.00%1100.00%
Total46100.00%1100.00%


__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); }

Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann7593.75%133.33%
Karl Beldan33.75%133.33%
Alexander Duyck22.50%133.33%
Total80100.00%3100.00%

EXPORT_SYMBOL(csum_tcpudp_nofold); #endif

Overall Contributors

PersonTokensPropCommitsCommitProp
Arnd Bergmann67688.95%545.45%
Karl Beldan496.45%218.18%
Ian Abbott273.55%19.09%
Vineet Gupta50.66%19.09%
Alexander Duyck20.26%19.09%
Paul Gortmaker10.13%19.09%
Total760100.00%11100.00%
Directory: lib
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