xref: /openbmc/linux/include/net/checksum.h (revision 5bd8e16d)
1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Checksumming functions for IP, TCP, UDP and so on
7  *
8  * Authors:	Jorge Cwik, <jorge@laser.satlink.net>
9  *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
10  *		Borrows very liberally from tcp.c and ip.c, see those
11  *		files for more names.
12  *
13  *		This program is free software; you can redistribute it and/or
14  *		modify it under the terms of the GNU General Public License
15  *		as published by the Free Software Foundation; either version
16  *		2 of the License, or (at your option) any later version.
17  */
18 
19 #ifndef _CHECKSUM_H
20 #define _CHECKSUM_H
21 
22 #include <linux/errno.h>
23 #include <asm/types.h>
24 #include <asm/byteorder.h>
25 #include <asm/uaccess.h>
26 #include <asm/checksum.h>
27 
28 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
29 static inline
30 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
31 				      int len, __wsum sum, int *err_ptr)
32 {
33 	if (access_ok(VERIFY_READ, src, len))
34 		return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
35 
36 	if (len)
37 		*err_ptr = -EFAULT;
38 
39 	return sum;
40 }
41 #endif
42 
43 #ifndef HAVE_CSUM_COPY_USER
44 static __inline__ __wsum csum_and_copy_to_user
45 (const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
46 {
47 	sum = csum_partial(src, len, sum);
48 
49 	if (access_ok(VERIFY_WRITE, dst, len)) {
50 		if (copy_to_user(dst, src, len) == 0)
51 			return sum;
52 	}
53 	if (len)
54 		*err_ptr = -EFAULT;
55 
56 	return (__force __wsum)-1; /* invalid checksum */
57 }
58 #endif
59 
60 static inline __wsum csum_add(__wsum csum, __wsum addend)
61 {
62 	u32 res = (__force u32)csum;
63 	res += (__force u32)addend;
64 	return (__force __wsum)(res + (res < (__force u32)addend));
65 }
66 
67 static inline __wsum csum_sub(__wsum csum, __wsum addend)
68 {
69 	return csum_add(csum, ~addend);
70 }
71 
72 static inline __wsum
73 csum_block_add(__wsum csum, __wsum csum2, int offset)
74 {
75 	u32 sum = (__force u32)csum2;
76 	if (offset&1)
77 		sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
78 	return csum_add(csum, (__force __wsum)sum);
79 }
80 
81 static inline __wsum
82 csum_block_sub(__wsum csum, __wsum csum2, int offset)
83 {
84 	u32 sum = (__force u32)csum2;
85 	if (offset&1)
86 		sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
87 	return csum_sub(csum, (__force __wsum)sum);
88 }
89 
90 static inline __wsum csum_unfold(__sum16 n)
91 {
92 	return (__force __wsum)n;
93 }
94 
95 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
96 
97 static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
98 {
99 	__be32 diff[] = { ~from, to };
100 
101 	*sum = csum_fold(csum_partial(diff, sizeof(diff), ~csum_unfold(*sum)));
102 }
103 
104 static inline void csum_replace2(__sum16 *sum, __be16 from, __be16 to)
105 {
106 	csum_replace4(sum, (__force __be32)from, (__force __be32)to);
107 }
108 
109 struct sk_buff;
110 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
111 			      __be32 from, __be32 to, int pseudohdr);
112 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
113 			       const __be32 *from, const __be32 *to,
114 			       int pseudohdr);
115 
116 static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
117 					    __be16 from, __be16 to,
118 					    int pseudohdr)
119 {
120 	inet_proto_csum_replace4(sum, skb, (__force __be32)from,
121 				 (__force __be32)to, pseudohdr);
122 }
123 
124 #endif
125