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184 lines
4.6 KiB
184 lines
4.6 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* arch/alpha/lib/checksum.c |
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* |
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* This file contains network checksum routines that are better done |
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* in an architecture-specific manner due to speed.. |
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* Comments in other versions indicate that the algorithms are from RFC1071 |
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* |
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* accelerated versions (and 21264 assembly versions ) contributed by |
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* Rick Gorton <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/string.h> |
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#include <asm/byteorder.h> |
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static inline unsigned short from64to16(unsigned long x) |
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{ |
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/* Using extract instructions is a bit more efficient |
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than the original shift/bitmask version. */ |
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union { |
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unsigned long ul; |
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unsigned int ui[2]; |
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unsigned short us[4]; |
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} in_v, tmp_v, out_v; |
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in_v.ul = x; |
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tmp_v.ul = (unsigned long) in_v.ui[0] + (unsigned long) in_v.ui[1]; |
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/* Since the bits of tmp_v.sh[3] are going to always be zero, |
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we don't have to bother to add that in. */ |
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out_v.ul = (unsigned long) tmp_v.us[0] + (unsigned long) tmp_v.us[1] |
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+ (unsigned long) tmp_v.us[2]; |
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/* Similarly, out_v.us[2] is always zero for the final add. */ |
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return out_v.us[0] + out_v.us[1]; |
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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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__sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, |
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__u32 len, __u8 proto, __wsum sum) |
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{ |
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return (__force __sum16)~from64to16( |
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(__force u64)saddr + (__force u64)daddr + |
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(__force u64)sum + ((len + proto) << 8)); |
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} |
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EXPORT_SYMBOL(csum_tcpudp_magic); |
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__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, |
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__u32 len, __u8 proto, __wsum sum) |
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{ |
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unsigned long result; |
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result = (__force u64)saddr + (__force u64)daddr + |
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(__force u64)sum + ((len + proto) << 8); |
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/* Fold down to 32-bits so we don't lose in the typedef-less |
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network stack. */ |
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/* 64 to 33 */ |
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result = (result & 0xffffffff) + (result >> 32); |
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/* 33 to 32 */ |
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result = (result & 0xffffffff) + (result >> 32); |
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return (__force __wsum)result; |
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} |
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EXPORT_SYMBOL(csum_tcpudp_nofold); |
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/* |
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* Do a 64-bit checksum on an arbitrary memory area.. |
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* |
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* This isn't a great routine, but it's not _horrible_ either. The |
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* inner loop could be unrolled a bit further, and there are better |
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* ways to do the carry, but this is reasonable. |
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*/ |
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static inline unsigned long do_csum(const unsigned char * buff, int len) |
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{ |
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int odd, count; |
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unsigned long result = 0; |
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if (len <= 0) |
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goto out; |
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odd = 1 & (unsigned long) buff; |
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if (odd) { |
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result = *buff << 8; |
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len--; |
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buff++; |
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} |
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count = len >> 1; /* nr of 16-bit words.. */ |
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if (count) { |
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if (2 & (unsigned long) buff) { |
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result += *(unsigned short *) buff; |
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count--; |
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len -= 2; |
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buff += 2; |
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} |
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count >>= 1; /* nr of 32-bit words.. */ |
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if (count) { |
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if (4 & (unsigned long) buff) { |
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result += *(unsigned int *) buff; |
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count--; |
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len -= 4; |
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buff += 4; |
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} |
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count >>= 1; /* nr of 64-bit words.. */ |
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if (count) { |
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unsigned long carry = 0; |
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do { |
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unsigned long w = *(unsigned long *) buff; |
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count--; |
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buff += 8; |
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result += carry; |
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result += w; |
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carry = (w > result); |
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} while (count); |
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result += carry; |
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result = (result & 0xffffffff) + (result >> 32); |
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} |
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if (len & 4) { |
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result += *(unsigned int *) buff; |
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buff += 4; |
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} |
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} |
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if (len & 2) { |
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result += *(unsigned short *) buff; |
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buff += 2; |
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} |
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} |
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if (len & 1) |
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result += *buff; |
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result = from64to16(result); |
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if (odd) |
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); |
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out: |
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return result; |
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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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__sum16 ip_fast_csum(const void *iph, unsigned int ihl) |
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{ |
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return (__force __sum16)~do_csum(iph,ihl*4); |
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} |
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EXPORT_SYMBOL(ip_fast_csum); |
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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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__wsum csum_partial(const void *buff, int len, __wsum sum) |
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{ |
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unsigned long result = do_csum(buff, len); |
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/* add in old sum, and carry.. */ |
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result += (__force u32)sum; |
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/* 32+c bits -> 32 bits */ |
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result = (result & 0xffffffff) + (result >> 32); |
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return (__force __wsum)result; |
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} |
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EXPORT_SYMBOL(csum_partial); |
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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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__sum16 ip_compute_csum(const void *buff, int len) |
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{ |
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return (__force __sum16)~from64to16(do_csum(buff,len)); |
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} |
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EXPORT_SYMBOL(ip_compute_csum);
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