1/*
2 *  linux/include/asm-arm/checksum.h
3 *
4 * IP checksum routines
5 *
6 * Copyright (C) Original authors of ../asm-i386/checksum.h
7 * Copyright (C) 1996-1999 Russell King
8 */
9#ifndef __ASM_ARM_CHECKSUM_H
10#define __ASM_ARM_CHECKSUM_H
11
12#include <linux/in6.h>
13
14/*
15 * computes the checksum of a memory block at buff, length len,
16 * and adds in "sum" (32-bit)
17 *
18 * returns a 32-bit number suitable for feeding into itself
19 * or csum_tcpudp_magic
20 *
21 * this function must be called with even lengths, except
22 * for the last fragment, which may be odd
23 *
24 * it's best to have buff aligned on a 32-bit boundary
25 */
26__wsum csum_partial(const void *buff, int len, __wsum sum);
27
28/*
29 * the same as csum_partial, but copies from src while it
30 * checksums, and handles user-space pointer exceptions correctly, when needed.
31 *
32 * here even more important to align src and dst on a 32-bit (or even
33 * better 64-bit) boundary
34 */
35
36__wsum
37csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);
38
39__wsum
40csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr);
41
42/*
43 *	This is a version of ip_compute_csum() optimized for IP headers,
44 *	which always checksum on 4 octet boundaries.
45 */
46static inline __sum16
47ip_fast_csum(const void *iph, unsigned int ihl)
48{
49	unsigned int sum, tmp1;
50
51	__asm__ __volatile__(
52	"ldr	%0, [%1], #4		@ ip_fast_csum		\n\
53	ldr	%3, [%1], #4					\n\
54	sub	%2, %2, #5					\n\
55	adds	%0, %0, %3					\n\
56	ldr	%3, [%1], #4					\n\
57	adcs	%0, %0, %3					\n\
58	ldr	%3, [%1], #4					\n\
591:	adcs	%0, %0, %3					\n\
60	ldr	%3, [%1], #4					\n\
61	tst	%2, #15			@ do this carefully	\n\
62	subne	%2, %2, #1		@ without destroying	\n\
63	bne	1b			@ the carry flag	\n\
64	adcs	%0, %0, %3					\n\
65	adc	%0, %0, #0					\n\
66	adds	%0, %0, %0, lsl #16				\n\
67	addcs	%0, %0, #0x10000				\n\
68	mvn	%0, %0						\n\
69	mov	%0, %0, lsr #16"
70	: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
71	: "1" (iph), "2" (ihl)
72	: "cc");
73	return (__force __sum16)sum;
74}
75
76/*
77 * 	Fold a partial checksum without adding pseudo headers
78 */
79static inline __sum16 csum_fold(__wsum sum)
80{
81	__asm__(
82	"adds	%0, %1, %1, lsl #16	@ csum_fold		\n\
83	addcs	%0, %0, #0x10000"
84	: "=r" (sum)
85	: "r" (sum)
86	: "cc");
87	return (__force __sum16)(~(__force u32)sum >> 16);
88}
89
90static inline __wsum
91csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
92		   unsigned short proto, __wsum sum)
93{
94	__asm__(
95	"adds	%0, %1, %2		@ csum_tcpudp_nofold	\n\
96	adcs	%0, %0, %3					\n\
97	adcs	%0, %0, %4					\n\
98	adcs	%0, %0, %5					\n\
99	adc	%0, %0, #0"
100	: "=&r"(sum)
101	: "r" (sum), "r" (daddr), "r" (saddr), "r" (htons(len)), "Ir" (htons(proto))
102	: "cc");
103	return sum;
104}
105/*
106 * computes the checksum of the TCP/UDP pseudo-header
107 * returns a 16-bit checksum, already complemented
108 */
109static inline __sum16
110csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
111		  unsigned short proto, __wsum sum)
112{
113	__asm__(
114	"adds	%0, %1, %2		@ csum_tcpudp_magic	\n\
115	adcs	%0, %0, %3					\n\
116	adcs	%0, %0, %4					\n\
117	adcs	%0, %0, %5					\n\
118	adc	%0, %0, #0					\n\
119	adds	%0, %0, %0, lsl #16				\n\
120	addcs	%0, %0, #0x10000				\n\
121	mvn	%0, %0"
122	: "=&r"(sum)
123	: "r" (sum), "r" (daddr), "r" (saddr), "r" (htons(len)), "Ir" (htons(proto))
124	: "cc");
125	return (__force __sum16)((__force u32)sum >> 16);
126}
127
128
129/*
130 * this routine is used for miscellaneous IP-like checksums, mainly
131 * in icmp.c
132 */
133static inline __sum16
134ip_compute_csum(const void *buff, int len)
135{
136	return csum_fold(csum_partial(buff, len, 0));
137}
138
139#define _HAVE_ARCH_IPV6_CSUM
140extern __wsum
141__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
142		__be32 proto, __wsum sum);
143
144static inline __sum16
145csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __u32 len,
146		unsigned short proto, __wsum sum)
147{
148	return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
149					   htonl(proto), sum));
150}
151#endif
152