148 lines
3.4 KiB
C
148 lines
3.4 KiB
C
/*
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* S390 fast network checksum routines
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*
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* S390 version
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* Copyright IBM Corp. 1999
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* Author(s): Ulrich Hild (first version)
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* Martin Schwidefsky (heavily optimized CKSM version)
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* D.J. Barrow (third attempt)
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*/
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#ifndef _S390_CHECKSUM_H
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#define _S390_CHECKSUM_H
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#include <asm/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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static inline __wsum
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csum_partial(const void *buff, int len, __wsum sum)
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{
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register unsigned long reg2 asm("2") = (unsigned long) buff;
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register unsigned long reg3 asm("3") = (unsigned long) len;
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asm volatile(
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"0: cksm %0,%1\n" /* do checksum on longs */
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" jo 0b\n"
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: "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
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return sum;
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}
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/*
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* the same as csum_partial_copy, but copies from user space.
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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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* Copy from userspace and compute checksum. If we catch an exception
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* then zero the rest of the buffer.
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*/
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static inline __wsum
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csum_partial_copy_from_user(const void __user *src, void *dst,
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int len, __wsum sum,
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int *err_ptr)
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{
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int missing;
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missing = copy_from_user(dst, src, len);
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if (missing) {
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memset(dst + len - missing, 0, missing);
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*err_ptr = -EFAULT;
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}
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return csum_partial(dst, len, sum);
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}
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static inline __wsum
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csum_partial_copy_nocheck (const void *src, void *dst, 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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* Fold a partial checksum without adding pseudo headers
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*/
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static inline __sum16 csum_fold(__wsum sum)
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{
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u32 csum = (__force u32) sum;
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csum += (csum >> 16) + (csum << 16);
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csum >>= 16;
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return (__force __sum16) ~csum;
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}
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/*
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* This is a version of ip_compute_csum() optimized for IP headers,
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* which always checksum on 4 octet boundaries.
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*
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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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return csum_fold(csum_partial(iph, ihl*4, 0));
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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 32-bit checksum
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*/
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static inline __wsum
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csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
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unsigned short len, unsigned short proto,
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__wsum sum)
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{
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__u32 csum = (__force __u32)sum;
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csum += (__force __u32)saddr;
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if (csum < (__force __u32)saddr)
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csum++;
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csum += (__force __u32)daddr;
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if (csum < (__force __u32)daddr)
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csum++;
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csum += len + proto;
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if (csum < len + proto)
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csum++;
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return (__force __wsum)csum;
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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
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csum_tcpudp_magic(__be32 saddr, __be32 daddr,
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unsigned short len, unsigned short 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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* this routine is used for miscellaneous IP-like checksums, mainly
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* in icmp.c
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*/
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static inline __sum16 ip_compute_csum(const void *buff, int len)
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{
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return csum_fold(csum_partial(buff, len, 0));
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}
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#endif /* _S390_CHECKSUM_H */
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