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 */
17asmlinkage 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
27asmlinkage 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 */
37static __inline__
38unsigned 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
44static __inline__
45unsigned 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
59unsigned 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 */
68static inline unsigned short ip_fast_csum(unsigned char * iph,
69					  unsigned int ihl)
70{
71	unsigned int sum;
72
73	__asm__ __volatile__(
74	    "movl (%1), %0	;\n"
75	    "subl $4, %2	;\n"
76	    "jbe 2f		;\n"
77	    "addl 4(%1), %0	;\n"
78	    "adcl 8(%1), %0	;\n"
79	    "adcl 12(%1), %0	;\n"
80"1:	    adcl 16(%1), %0	;\n"
81	    "lea 4(%1), %1	;\n"
82	    "decl %2		;\n"
83	    "jne 1b		;\n"
84	    "adcl $0, %0	;\n"
85	    "movl %0, %2	;\n"
86	    "shrl $16, %0	;\n"
87	    "addw %w2, %w0	;\n"
88	    "adcl $0, %0	;\n"
89	    "notl %0		;\n"
90"2:				;\n"
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
103static inline unsigned int csum_fold(unsigned int sum)
104{
105	__asm__(
106		"addl %1, %0		;\n"
107		"adcl $0xffff, %0	;\n"
108		: "=r" (sum)
109		: "r" (sum << 16), "0" (sum & 0xffff0000)
110	);
111	return (~sum) >> 16;
112}
113
114static inline unsigned long csum_tcpudp_nofold(unsigned long saddr,
115						   unsigned long daddr,
116						   unsigned short len,
117						   unsigned short proto,
118						   unsigned int 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"((ntohs(len)<<16)+proto*256), "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 */
134static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
135						   unsigned long daddr,
136						   unsigned short len,
137						   unsigned short proto,
138						   unsigned int sum)
139{
140	return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
141}
142
143/*
144 * this routine is used for miscellaneous IP-like checksums, mainly
145 * in icmp.c
146 */
147
148static inline unsigned short ip_compute_csum(unsigned char * buff, int len)
149{
150    return csum_fold (csum_partial(buff, len, 0));
151}
152
153#define _HAVE_ARCH_IPV6_CSUM
154static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
155						     struct in6_addr *daddr,
156						     __u32 len,
157						     unsigned short proto,
158						     unsigned int sum)
159{
160	__asm__(
161		"addl 0(%1), %0		;\n"
162		"adcl 4(%1), %0		;\n"
163		"adcl 8(%1), %0		;\n"
164		"adcl 12(%1), %0	;\n"
165		"adcl 0(%2), %0		;\n"
166		"adcl 4(%2), %0		;\n"
167		"adcl 8(%2), %0		;\n"
168		"adcl 12(%2), %0	;\n"
169		"adcl %3, %0		;\n"
170		"adcl %4, %0		;\n"
171		"adcl $0, %0		;\n"
172		: "=&r" (sum)
173		: "r" (saddr), "r" (daddr),
174		  "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
175
176	return csum_fold(sum);
177}
178
179/*
180 *	Copy and checksum to user
181 */
182#define HAVE_CSUM_COPY_USER
183static __inline__ unsigned int csum_and_copy_to_user(const char *src, char *dst,
184				    int len, int sum, int *err_ptr)
185{
186	if (access_ok(VERIFY_WRITE, dst, len))
187		return csum_partial_copy_generic(src, dst, len, sum, NULL, err_ptr);
188
189	if (len)
190		*err_ptr = -EFAULT;
191
192	return -1; /* invalid checksum */
193}
194
195#endif
196