1/*
2 *  arch/arm/include/asm/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 * 	Fold a partial checksum without adding pseudo headers
44 */
45static inline __sum16 csum_fold(__wsum sum)
46{
47	__asm__(
48	"add	%0, %1, %1, ror #16	@ csum_fold"
49	: "=r" (sum)
50	: "r" (sum)
51	: "cc");
52	return (__force __sum16)(~(__force u32)sum >> 16);
53}
54
55/*
56 *	This is a version of ip_compute_csum() optimized for IP headers,
57 *	which always checksum on 4 octet boundaries.
58 */
59static inline __sum16
60ip_fast_csum(const void *iph, unsigned int ihl)
61{
62	unsigned int tmp1;
63	__wsum sum;
64
65	__asm__ __volatile__(
66	"ldr	%0, [%1], #4		@ ip_fast_csum		\n\
67	ldr	%3, [%1], #4					\n\
68	sub	%2, %2, #5					\n\
69	adds	%0, %0, %3					\n\
70	ldr	%3, [%1], #4					\n\
71	adcs	%0, %0, %3					\n\
72	ldr	%3, [%1], #4					\n\
731:	adcs	%0, %0, %3					\n\
74	ldr	%3, [%1], #4					\n\
75	tst	%2, #15			@ do this carefully	\n\
76	subne	%2, %2, #1		@ without destroying	\n\
77	bne	1b			@ the carry flag	\n\
78	adcs	%0, %0, %3					\n\
79	adc	%0, %0, #0"
80	: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
81	: "1" (iph), "2" (ihl)
82	: "cc", "memory");
83	return csum_fold(sum);
84}
85
86static inline __wsum
87csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
88		   unsigned short proto, __wsum sum)
89{
90	u32 lenprot = len | proto << 16;
91	if (__builtin_constant_p(sum) && sum == 0) {
92		__asm__(
93		"adds	%0, %1, %2	@ csum_tcpudp_nofold0	\n\t"
94#ifdef __ARMEB__
95		"adcs	%0, %0, %3				\n\t"
96#else
97		"adcs	%0, %0, %3, ror #8			\n\t"
98#endif
99		"adc	%0, %0, #0"
100		: "=&r" (sum)
101		: "r" (daddr), "r" (saddr), "r" (lenprot)
102		: "cc");
103	} else {
104		__asm__(
105		"adds	%0, %1, %2	@ csum_tcpudp_nofold	\n\t"
106		"adcs	%0, %0, %3				\n\t"
107#ifdef __ARMEB__
108		"adcs	%0, %0, %4				\n\t"
109#else
110		"adcs	%0, %0, %4, ror #8			\n\t"
111#endif
112		"adc	%0, %0, #0"
113		: "=&r"(sum)
114		: "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot)
115		: "cc");
116	}
117	return sum;
118}
119/*
120 * computes the checksum of the TCP/UDP pseudo-header
121 * returns a 16-bit checksum, already complemented
122 */
123static inline __sum16
124csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
125		  unsigned short proto, __wsum sum)
126{
127	return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
128}
129
130
131/*
132 * this routine is used for miscellaneous IP-like checksums, mainly
133 * in icmp.c
134 */
135static inline __sum16
136ip_compute_csum(const void *buff, int len)
137{
138	return csum_fold(csum_partial(buff, len, 0));
139}
140
141#define _HAVE_ARCH_IPV6_CSUM
142extern __wsum
143__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
144		__be32 proto, __wsum sum);
145
146static inline __sum16
147csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __u32 len,
148		unsigned short proto, __wsum sum)
149{
150	return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
151					   htonl(proto), sum));
152}
153#endif
154