155 lines
3.7 KiB
C
155 lines
3.7 KiB
C
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#ifndef __UM_CHECKSUM_H
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#define __UM_CHECKSUM_H
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#include <linux/string.h>
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#include <linux/in6.h>
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#include <linux/uaccess.h>
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/*
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* computes the checksum of a memory block at buff, length len,
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* and adds in "sum" (32-bit)
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*
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* returns a 32-bit number suitable for feeding into itself
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* or csum_tcpudp_magic
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*
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* this function must be called with even lengths, except
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* for the last fragment, which may be odd
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*
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* it's best to have buff aligned on a 32-bit boundary
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*/
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extern __wsum csum_partial(const void *buff, int len, __wsum sum);
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/*
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* Note: when you get a NULL pointer exception here this means someone
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* passed in an incorrect kernel address to one of these functions.
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*
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* If you use these functions directly please don't forget the
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* access_ok().
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*/
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static __inline__
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__wsum csum_partial_copy_nocheck(const void *src, void *dst,
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int len, __wsum sum)
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{
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memcpy(dst, src, len);
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return csum_partial(dst, len, sum);
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}
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/*
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* the same as csum_partial, but copies from src while it
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* checksums, and handles user-space pointer exceptions correctly, when needed.
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*
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* here even more important to align src and dst on a 32-bit (or even
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* better 64-bit) boundary
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*/
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static __inline__
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__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
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int len, __wsum sum, int *err_ptr)
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{
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if (copy_from_user(dst, src, len)) {
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*err_ptr = -EFAULT;
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return (__force __wsum)-1;
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}
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return csum_partial(dst, len, sum);
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}
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/**
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* csum_fold - Fold and invert a 32bit checksum.
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* sum: 32bit unfolded sum
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*
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* Fold a 32bit running checksum to 16bit and invert it. This is usually
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* the last step before putting a checksum into a packet.
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* Make sure not to mix with 64bit checksums.
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*/
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static inline __sum16 csum_fold(__wsum sum)
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{
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__asm__(
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" addl %1,%0\n"
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" adcl $0xffff,%0"
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: "=r" (sum)
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: "r" ((__force u32)sum << 16),
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"0" ((__force u32)sum & 0xffff0000)
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);
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return (__force __sum16)(~(__force u32)sum >> 16);
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}
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/**
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* csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
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* @saddr: source address
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* @daddr: destination address
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* @len: length of packet
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* @proto: ip protocol of packet
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* @sum: initial sum to be added in (32bit unfolded)
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*
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* Returns the pseudo header checksum the input data. Result is
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* 32bit unfolded.
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*/
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static inline __wsum
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csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
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__u8 proto, __wsum sum)
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{
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asm(" addl %1, %0\n"
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" adcl %2, %0\n"
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" adcl %3, %0\n"
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" adcl $0, %0\n"
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: "=r" (sum)
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: "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum));
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return sum;
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}
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/*
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* computes the checksum of the TCP/UDP pseudo-header
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* returns a 16-bit checksum, already complemented
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*/
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static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
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__u32 len, __u8 proto,
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__wsum sum)
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{
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return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
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}
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/**
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* ip_fast_csum - Compute the IPv4 header checksum efficiently.
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* iph: ipv4 header
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* ihl: length of header / 4
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*/
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static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
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{
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unsigned int sum;
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asm( " movl (%1), %0\n"
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" subl $4, %2\n"
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" jbe 2f\n"
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" addl 4(%1), %0\n"
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" adcl 8(%1), %0\n"
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" adcl 12(%1), %0\n"
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"1: adcl 16(%1), %0\n"
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" lea 4(%1), %1\n"
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" decl %2\n"
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" jne 1b\n"
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" adcl $0, %0\n"
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" movl %0, %2\n"
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" shrl $16, %0\n"
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" addw %w2, %w0\n"
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" adcl $0, %0\n"
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" notl %0\n"
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"2:"
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/* Since the input registers which are loaded with iph and ipl
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are modified, we must also specify them as outputs, or gcc
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will assume they contain their original values. */
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: "=r" (sum), "=r" (iph), "=r" (ihl)
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: "1" (iph), "2" (ihl)
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: "memory");
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return (__force __sum16)sum;
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}
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#ifdef CONFIG_X86_32
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# include "checksum_32.h"
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#else
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# include "checksum_64.h"
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#endif
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#endif
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