File: /usr/include/asm/checksum.h
1 #ifndef _I386_CHECKSUM_H
2 #define _I386_CHECKSUM_H
3
4
5 /*
6 * computes the checksum of a memory block at buff, length len,
7 * and adds in "sum" (32-bit)
8 *
9 * returns a 32-bit number suitable for feeding into itself
10 * or csum_tcpudp_magic
11 *
12 * this function must be called with even lengths, except
13 * for the last fragment, which may be odd
14 *
15 * it's best to have buff aligned on a 32-bit boundary
16 */
17 asmlinkage unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
18
19 /*
20 * the same as csum_partial, but copies from src while it
21 * checksums, and handles user-space pointer exceptions correctly, when needed.
22 *
23 * here even more important to align src and dst on a 32-bit (or even
24 * better 64-bit) boundary
25 */
26
27 asmlinkage unsigned int csum_partial_copy_generic( const char *src, char *dst, int len, int sum,
28 int *src_err_ptr, int *dst_err_ptr);
29
30 /*
31 * Note: when you get a NULL pointer exception here this means someone
32 * passed in an incorrect kernel address to one of these functions.
33 *
34 * If you use these functions directly please don't forget the
35 * verify_area().
36 */
37 extern __inline__
38 unsigned int csum_partial_copy_nocheck ( const char *src, char *dst,
39 int len, int sum)
40 {
41 return csum_partial_copy_generic ( src, dst, len, sum, NULL, NULL);
42 }
43
44 extern __inline__
45 unsigned int csum_partial_copy_from_user ( const char *src, char *dst,
46 int len, int sum, int *err_ptr)
47 {
48 return csum_partial_copy_generic ( src, dst, len, sum, err_ptr, NULL);
49 }
50
51 /*
52 * These are the old (and unsafe) way of doing checksums, a warning message will be
53 * printed if they are used and an exeption occurs.
54 *
55 * these functions should go away after some time.
56 */
57
58 #define csum_partial_copy_fromuser csum_partial_copy
59 unsigned int csum_partial_copy( const char *src, char *dst, int len, int sum);
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 */
68 static inline unsigned short ip_fast_csum(unsigned char * iph,
69 unsigned int ihl) {
70 unsigned int sum;
71
72 __asm__ __volatile__("
73 movl (%1), %0
74 subl $4, %2
75 jbe 2f
76 addl 4(%1), %0
77 adcl 8(%1), %0
78 adcl 12(%1), %0
79 1: adcl 16(%1), %0
80 lea 4(%1), %1
81 decl %2
82 jne 1b
83 adcl $0, %0
84 movl %0, %2
85 shrl $16, %0
86 addw %w2, %w0
87 adcl $0, %0
88 notl %0
89 2:
90 "
91 /* Since the input registers which are loaded with iph and ipl
92 are modified, we must also specify them as outputs, or gcc
93 will assume they contain their original values. */
94 : "=r" (sum), "=r" (iph), "=r" (ihl)
95 : "1" (iph), "2" (ihl));
96 return(sum);
97 }
98
99 /*
100 * Fold a partial checksum
101 */
102
103 static inline unsigned int csum_fold(unsigned int sum)
104 {
105 __asm__("
106 addl %1, %0
107 adcl $0xffff, %0
108 "
109 : "=r" (sum)
110 : "r" (sum << 16), "0" (sum & 0xffff0000)
111 );
112 return (~sum) >> 16;
113 }
114
115 static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
116 unsigned long daddr,
117 unsigned short len,
118 unsigned short proto,
119 unsigned int sum)
120 {
121 __asm__("
122 addl %1, %0
123 adcl %2, %0
124 adcl %3, %0
125 adcl $0, %0
126 "
127 : "=r" (sum)
128 : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));
129 return sum;
130 }
131
132 /*
133 * computes the checksum of the TCP/UDP pseudo-header
134 * returns a 16-bit checksum, already complemented
135 */
136 static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
137 unsigned long daddr,
138 unsigned short len,
139 unsigned short proto,
140 unsigned int sum)
141 {
142 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
143 }
144
145 /*
146 * this routine is used for miscellaneous IP-like checksums, mainly
147 * in icmp.c
148 */
149
150 static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {
151 return csum_fold (csum_partial(buff, len, 0));
152 }
153
154 #define _HAVE_ARCH_IPV6_CSUM
155 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
156 struct in6_addr *daddr,
157 __u32 len,
158 unsigned short proto,
159 unsigned int sum)
160 {
161 __asm__("
162 addl 0(%1), %0
163 adcl 4(%1), %0
164 adcl 8(%1), %0
165 adcl 12(%1), %0
166 adcl 0(%2), %0
167 adcl 4(%2), %0
168 adcl 8(%2), %0
169 adcl 12(%2), %0
170 adcl %3, %0
171 adcl %4, %0
172 adcl $0, %0
173 "
174 : "=&r" (sum)
175 : "r" (saddr), "r" (daddr),
176 "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
177
178 return csum_fold(sum);
179 }
180
181 /*
182 * Copy and checksum to user
183 */
184 #define HAVE_CSUM_COPY_USER
185 static __inline__ unsigned int csum_and_copy_to_user (const char *src, char *dst,
186 int len, int sum, int *err_ptr)
187 {
188 if (access_ok(VERIFY_WRITE, dst, len))
189 return csum_partial_copy_generic(src, dst, len, sum, NULL, err_ptr);
190
191 if (len)
192 *err_ptr = -EFAULT;
193
194 return -1; /* invalid checksum */
195 }
196
197 #endif
198