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1 #ifndef _S390_CHECKSUM_H
2 #define _S390_CHECKSUM_H
3 
4 /*
5  *  include/asm-s390/checksum.h
6  *    S390 fast network checksum routines
7  *    see also arch/S390/lib/checksum.c
8  *
9  *  S390 version
10  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
11  *    Author(s): Ulrich Hild        (first version)
12  *               Martin Schwidefsky (heavily optimized CKSM version)
13  *               D.J. Barrow        (third attempt)
14  */
15 
16 #include <asm/uaccess.h>
17 
18 /*
19  * computes the checksum of a memory block at buff, length len,
20  * and adds in "sum" (32-bit)
21  *
22  * returns a 32-bit number suitable for feeding into itself
23  * or csum_tcpudp_magic
24  *
25  * this function must be called with even lengths, except
26  * for the last fragment, which may be odd
27  *
28  * it's best to have buff aligned on a 32-bit boundary
29  */
30 static inline __wsum
csum_partial(const void * buff,int len,__wsum sum)31 csum_partial(const void *buff, int len, __wsum sum)
32 {
33 	register unsigned long reg2 asm("2") = (unsigned long) buff;
34 	register unsigned long reg3 asm("3") = (unsigned long) len;
35 
36 	asm volatile(
37 		"0:	cksm	%0,%1\n"	/* do checksum on longs */
38 		"	jo	0b\n"
39 		: "+d" (sum), "+d" (reg2), "+d" (reg3) : : "cc", "memory");
40 	return sum;
41 }
42 
43 /*
44  * the same as csum_partial_copy, but copies from user space.
45  *
46  * here even more important to align src and dst on a 32-bit (or even
47  * better 64-bit) boundary
48  *
49  * Copy from userspace and compute checksum.  If we catch an exception
50  * then zero the rest of the buffer.
51  */
52 static inline __wsum
csum_partial_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)53 csum_partial_copy_from_user(const void __user *src, void *dst,
54                                           int len, __wsum sum,
55                                           int *err_ptr)
56 {
57 	int missing;
58 
59 	missing = copy_from_user(dst, src, len);
60 	if (missing) {
61 		memset(dst + len - missing, 0, missing);
62 		*err_ptr = -EFAULT;
63 	}
64 
65 	return csum_partial(dst, len, sum);
66 }
67 
68 
69 static inline __wsum
csum_partial_copy_nocheck(const void * src,void * dst,int len,__wsum sum)70 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
71 {
72         memcpy(dst,src,len);
73 	return csum_partial(dst, len, sum);
74 }
75 
76 /*
77  *      Fold a partial checksum without adding pseudo headers
78  */
csum_fold(__wsum sum)79 static inline __sum16 csum_fold(__wsum sum)
80 {
81 	u32 csum = (__force u32) sum;
82 
83 	csum += (csum >> 16) + (csum << 16);
84 	csum >>= 16;
85 	return (__force __sum16) ~csum;
86 }
87 
88 /*
89  *	This is a version of ip_compute_csum() optimized for IP headers,
90  *	which always checksum on 4 octet boundaries.
91  *
92  */
ip_fast_csum(const void * iph,unsigned int ihl)93 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
94 {
95 	return csum_fold(csum_partial(iph, ihl*4, 0));
96 }
97 
98 /*
99  * computes the checksum of the TCP/UDP pseudo-header
100  * returns a 32-bit checksum
101  */
102 static inline __wsum
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)103 csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
104                    unsigned short len, unsigned short proto,
105                    __wsum sum)
106 {
107 	__u32 csum = (__force __u32)sum;
108 
109 	csum += (__force __u32)saddr;
110 	if (csum < (__force __u32)saddr)
111 		csum++;
112 
113 	csum += (__force __u32)daddr;
114 	if (csum < (__force __u32)daddr)
115 		csum++;
116 
117 	csum += len + proto;
118 	if (csum < len + proto)
119 		csum++;
120 
121 	return (__force __wsum)csum;
122 }
123 
124 /*
125  * computes the checksum of the TCP/UDP pseudo-header
126  * returns a 16-bit checksum, already complemented
127  */
128 
129 static inline __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)130 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
131                   unsigned short len, unsigned short proto,
132                   __wsum sum)
133 {
134 	return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
135 }
136 
137 /*
138  * this routine is used for miscellaneous IP-like checksums, mainly
139  * in icmp.c
140  */
141 
ip_compute_csum(const void * buff,int len)142 static inline __sum16 ip_compute_csum(const void *buff, int len)
143 {
144 	return csum_fold(csum_partial(buff, len, 0));
145 }
146 
147 #endif /* _S390_CHECKSUM_H */
148 
149 
150