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    Subject[PATCH 17/27] add generic lib/checksum.c
    Add a generic (unoptimized) implementation of checksum.c in pure C
    for use by all architectures.

    Based on microblaze code by Michal Simek <monstr@monstr.eu>

    Cc: Michal Simek <monstr@monstr.eu>
    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
    ---
    include/asm-generic/checksum.h | 79 +++++++++++++++++
    lib/Makefile | 2 +
    lib/checksum.c | 188 ++++++++++++++++++++++++++++++++++++++++
    3 files changed, 269 insertions(+), 0 deletions(-)
    create mode 100644 include/asm-generic/checksum.h
    create mode 100644 lib/checksum.c

    diff --git a/include/asm-generic/checksum.h b/include/asm-generic/checksum.h
    new file mode 100644
    index 0000000..4647c76
    --- /dev/null
    +++ b/include/asm-generic/checksum.h
    @@ -0,0 +1,79 @@
    +#ifndef __ASM_GENERIC_CHECKSUM_H
    +#define __ASM_GENERIC_CHECKSUM_H
    +
    +/*
    + * 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
    + */
    +extern __wsum csum_partial(const void *buff, int len, __wsum sum);
    +
    +/*
    + * the same as csum_partial, but copies from src while it
    + * checksums
    + *
    + * here even more important to align src and dst on a 32-bit (or even
    + * better 64-bit) boundary
    + */
    +extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);
    +
    +/*
    + * the same as csum_partial_copy, but copies from user space.
    + *
    + * here even more important to align src and dst on a 32-bit (or even
    + * better 64-bit) boundary
    + */
    +extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
    + int len, __wsum sum, int *csum_err);
    +
    +#define csum_partial_copy_nocheck(src, dst, len, sum) \
    + csum_partial_copy((src), (dst), (len), (sum))
    +
    +/*
    + * This is a version of ip_compute_csum() optimized for IP headers,
    + * which always checksum on 4 octet boundaries.
    + */
    +extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
    +
    +/*
    + * Fold a partial checksum
    + */
    +static inline __sum16 csum_fold(__wsum csum)
    +{
    + u32 sum = (__force u32)csum;
    + sum = (sum & 0xffff) + (sum >> 16);
    + sum = (sum & 0xffff) + (sum >> 16);
    + return (__force __sum16)~sum;
    +}
    +
    +#ifndef csum_tcpudp_nofold
    +/*
    + * computes the checksum of the TCP/UDP pseudo-header
    + * returns a 16-bit checksum, already complemented
    + */
    +extern __wsum
    +csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
    + unsigned short proto, __wsum sum);
    +#endif
    +
    +static inline __sum16
    +csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
    + unsigned short proto, __wsum sum)
    +{
    + return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
    +}
    +
    +/*
    + * this routine is used for miscellaneous IP-like checksums, mainly
    + * in icmp.c
    + */
    +extern __sum16 ip_compute_csum(const void *buff, int len);
    +
    +#endif /* __ASM_GENERIC_CHECKSUM_H */
    diff --git a/lib/Makefile b/lib/Makefile
    index 33a40e4..b6869e1 100644
    --- a/lib/Makefile
    +++ b/lib/Makefile
    @@ -92,6 +92,8 @@ obj-$(CONFIG_NLATTR) += nlattr.o

    obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o

    +obj-$(CONFIG_GENERIC_CSUM) += checksum.o
    +
    hostprogs-y := gen_crc32table
    clean-files := crc32table.h

    diff --git a/lib/checksum.c b/lib/checksum.c
    new file mode 100644
    index 0000000..4f80a4d
    --- /dev/null
    +++ b/lib/checksum.c
    @@ -0,0 +1,188 @@
    +/*
    + * arch/microblaze/lib/checksum.c
    + *
    + * Copyright (C) 2008 Michal Simek <monstr@monstr.eu>
    + *
    + * 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 <net/checksum.h>
    +#include <asm-generic/checksum.h>
    +#include <linux/module.h>
    +#include <asm/byteorder.h>
    +
    +static inline unsigned short from32to16(unsigned long 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, count;
    + unsigned long result = 0;
    +
    + if (len <= 0)
    + goto out;
    + odd = 1 & (unsigned long) buff;
    + if (odd) {
    + result = *buff;
    + len--;
    + buff++;
    + }
    + count = len >> 1; /* nr of 16-bit words.. */
    + if (count) {
    + if (2 & (unsigned long) buff) {
    + result += *(unsigned short *) buff;
    + count--;
    + len -= 2;
    + buff += 2;
    + }
    + count >>= 1; /* nr of 32-bit words.. */
    + if (count) {
    + unsigned long carry = 0;
    + do {
    + unsigned long w = *(unsigned long *) buff;
    + count--;
    + buff += 4;
    + result += carry;
    + result += w;
    + carry = (w > result);
    + } while (count);
    + result += carry;
    + result = (result & 0xffff) + (result >> 16);
    + }
    + if (len & 2) {
    + result += *(unsigned short *) buff;
    + buff += 2;
    + }
    + }
    + if (len & 1)
    + result += (*buff << 8);
    + result = from32to16(result);
    + if (odd)
    + result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
    +out:
    + return result;
    +}
    +
    +/*
    + * 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 ~do_csum(iph, ihl*4);
    +}
    +
    +/*
    + * 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 sum)
    +{
    + unsigned int result = do_csum(buff, len);
    +
    + /* add in old sum, and carry.. */
    + result += sum;
    + if (sum > result)
    + result += 1;
    + return 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 ~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)
    +{
    + if (csum_err)
    + *csum_err = 0;
    + memcpy(dst, src, len);
    + 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
    +__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
    + unsigned short len,
    + unsigned short 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
    + s += (s >> 32);
    + return (__force __wsum)s;
    +}
    +EXPORT_SYMBOL(csum_tcpudp_nofold);
    +#endif
    --
    1.5.6.3



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