1 /*
2 * Licensed under the GPL
3 */
4
5 #ifndef __UM_SYSDEP_CHECKSUM_H
6 #define __UM_SYSDEP_CHECKSUM_H
7
8 #include "linux/in6.h"
9 #include "linux/string.h"
10
11 /*
12 * computes the checksum of a memory block at buff, length len,
13 * and adds in "sum" (32-bit)
14 *
15 * returns a 32-bit number suitable for feeding into itself
16 * or csum_tcpudp_magic
17 *
18 * this function must be called with even lengths, except
19 * for the last fragment, which may be odd
20 *
21 * it's best to have buff aligned on a 32-bit boundary
22 */
23 __wsum csum_partial(const void *buff, int len, __wsum sum);
24
25 /*
26 * Note: when you get a NULL pointer exception here this means someone
27 * passed in an incorrect kernel address to one of these functions.
28 *
29 * If you use these functions directly please don't forget the
30 * access_ok().
31 */
32
33 static __inline__
csum_partial_copy_nocheck(const void * src,void * dst,int len,__wsum sum)34 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
35 int len, __wsum sum)
36 {
37 memcpy(dst, src, len);
38 return csum_partial(dst, len, sum);
39 }
40
41 /*
42 * the same as csum_partial, but copies from src while it
43 * checksums, and handles user-space pointer exceptions correctly, when needed.
44 *
45 * here even more important to align src and dst on a 32-bit (or even
46 * better 64-bit) boundary
47 */
48
49 static __inline__
csum_partial_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)50 __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
51 int len, __wsum sum, int *err_ptr)
52 {
53 if (copy_from_user(dst, src, len)) {
54 *err_ptr = -EFAULT;
55 return (__force __wsum)-1;
56 }
57
58 return csum_partial(dst, len, sum);
59 }
60
61 /*
62 * This is a version of ip_compute_csum() optimized for IP headers,
63 * which always checksum on 4 octet boundaries.
64 *
65 * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
66 * Arnt Gulbrandsen.
67 */
ip_fast_csum(const void * iph,unsigned int ihl)68 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
69 {
70 unsigned int sum;
71
72 __asm__ __volatile__(
73 "movl (%1), %0 ;\n"
74 "subl $4, %2 ;\n"
75 "jbe 2f ;\n"
76 "addl 4(%1), %0 ;\n"
77 "adcl 8(%1), %0 ;\n"
78 "adcl 12(%1), %0 ;\n"
79 "1: adcl 16(%1), %0 ;\n"
80 "lea 4(%1), %1 ;\n"
81 "decl %2 ;\n"
82 "jne 1b ;\n"
83 "adcl $0, %0 ;\n"
84 "movl %0, %2 ;\n"
85 "shrl $16, %0 ;\n"
86 "addw %w2, %w0 ;\n"
87 "adcl $0, %0 ;\n"
88 "notl %0 ;\n"
89 "2: ;\n"
90 /* Since the input registers which are loaded with iph and ipl
91 are modified, we must also specify them as outputs, or gcc
92 will assume they contain their original values. */
93 : "=r" (sum), "=r" (iph), "=r" (ihl)
94 : "1" (iph), "2" (ihl)
95 : "memory");
96 return (__force __sum16)sum;
97 }
98
99 /*
100 * Fold a partial checksum
101 */
102
csum_fold(__wsum sum)103 static inline __sum16 csum_fold(__wsum sum)
104 {
105 __asm__(
106 "addl %1, %0 ;\n"
107 "adcl $0xffff, %0 ;\n"
108 : "=r" (sum)
109 : "r" ((__force u32)sum << 16),
110 "0" ((__force u32)sum & 0xffff0000)
111 );
112 return (__force __sum16)(~(__force u32)sum >> 16);
113 }
114
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)115 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
116 unsigned short len,
117 unsigned short proto,
118 __wsum sum)
119 {
120 __asm__(
121 "addl %1, %0 ;\n"
122 "adcl %2, %0 ;\n"
123 "adcl %3, %0 ;\n"
124 "adcl $0, %0 ;\n"
125 : "=r" (sum)
126 : "g" (daddr), "g"(saddr), "g"((len + proto) << 8), "0"(sum));
127 return sum;
128 }
129
130 /*
131 * computes the checksum of the TCP/UDP pseudo-header
132 * returns a 16-bit checksum, already complemented
133 */
csum_tcpudp_magic(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)134 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
135 unsigned short len,
136 unsigned short proto,
137 __wsum sum)
138 {
139 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
140 }
141
142 /*
143 * this routine is used for miscellaneous IP-like checksums, mainly
144 * in icmp.c
145 */
146
ip_compute_csum(const void * buff,int len)147 static inline __sum16 ip_compute_csum(const void *buff, int len)
148 {
149 return csum_fold (csum_partial(buff, len, 0));
150 }
151
152 #define _HAVE_ARCH_IPV6_CSUM
csum_ipv6_magic(const struct in6_addr * saddr,const struct in6_addr * daddr,__u32 len,unsigned short proto,__wsum sum)153 static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
154 const struct in6_addr *daddr,
155 __u32 len, unsigned short proto,
156 __wsum sum)
157 {
158 __asm__(
159 "addl 0(%1), %0 ;\n"
160 "adcl 4(%1), %0 ;\n"
161 "adcl 8(%1), %0 ;\n"
162 "adcl 12(%1), %0 ;\n"
163 "adcl 0(%2), %0 ;\n"
164 "adcl 4(%2), %0 ;\n"
165 "adcl 8(%2), %0 ;\n"
166 "adcl 12(%2), %0 ;\n"
167 "adcl %3, %0 ;\n"
168 "adcl %4, %0 ;\n"
169 "adcl $0, %0 ;\n"
170 : "=&r" (sum)
171 : "r" (saddr), "r" (daddr),
172 "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
173
174 return csum_fold(sum);
175 }
176
177 /*
178 * Copy and checksum to user
179 */
180 #define HAVE_CSUM_COPY_USER
csum_and_copy_to_user(const void * src,void __user * dst,int len,__wsum sum,int * err_ptr)181 static __inline__ __wsum csum_and_copy_to_user(const void *src,
182 void __user *dst,
183 int len, __wsum sum, int *err_ptr)
184 {
185 if (access_ok(VERIFY_WRITE, dst, len)) {
186 if (copy_to_user(dst, src, len)) {
187 *err_ptr = -EFAULT;
188 return (__force __wsum)-1;
189 }
190
191 return csum_partial(src, len, sum);
192 }
193
194 if (len)
195 *err_ptr = -EFAULT;
196
197 return (__force __wsum)-1; /* invalid checksum */
198 }
199
200 #endif
201
202