1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 *  arch/arm/include/asm/checksum.h
4 *
5 * IP checksum routines
6 *
7 * Copyright (C) Original authors of ../asm-i386/checksum.h
8 * Copyright (C) 1996-1999 Russell King
9 */
10#ifndef __ASM_ARM_CHECKSUM_H
11#define __ASM_ARM_CHECKSUM_H
12
13#include <linux/in6.h>
14#include <linux/uaccess.h>
15
16/*
17 * computes the checksum of a memory block at buff, length len,
18 * and adds in "sum" (32-bit)
19 *
20 * returns a 32-bit number suitable for feeding into itself
21 * or csum_tcpudp_magic
22 *
23 * this function must be called with even lengths, except
24 * for the last fragment, which may be odd
25 *
26 * it's best to have buff aligned on a 32-bit boundary
27 */
28__wsum csum_partial(const void *buff, int len, __wsum sum);
29
30/*
31 * the same as csum_partial, but copies from src while it
32 * checksums, and handles user-space pointer exceptions correctly, when needed.
33 *
34 * here even more important to align src and dst on a 32-bit (or even
35 * better 64-bit) boundary
36 */
37
38__wsum
39csum_partial_copy_nocheck(const void *src, void *dst, int len);
40
41__wsum
42csum_partial_copy_from_user(const void __user *src, void *dst, int len);
43
44#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
45#define _HAVE_ARCH_CSUM_AND_COPY
46static inline
47__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
48{
49	if (!access_ok(src, len))
50		return 0;
51
52	return csum_partial_copy_from_user(src, dst, len);
53}
54
55/*
56 * 	Fold a partial checksum without adding pseudo headers
57 */
58static inline __sum16 csum_fold(__wsum sum)
59{
60	__asm__(
61	"add	%0, %1, %1, ror #16	@ csum_fold"
62	: "=r" (sum)
63	: "r" (sum)
64	: "cc");
65	return (__force __sum16)(~(__force u32)sum >> 16);
66}
67
68/*
69 *	This is a version of ip_compute_csum() optimized for IP headers,
70 *	which always checksum on 4 octet boundaries.
71 */
72static inline __sum16
73ip_fast_csum(const void *iph, unsigned int ihl)
74{
75	unsigned int tmp1;
76	__wsum sum;
77
78	__asm__ __volatile__(
79	"ldr	%0, [%1], #4		@ ip_fast_csum		\n\
80	ldr	%3, [%1], #4					\n\
81	sub	%2, %2, #5					\n\
82	adds	%0, %0, %3					\n\
83	ldr	%3, [%1], #4					\n\
84	adcs	%0, %0, %3					\n\
85	ldr	%3, [%1], #4					\n\
861:	adcs	%0, %0, %3					\n\
87	ldr	%3, [%1], #4					\n\
88	tst	%2, #15			@ do this carefully	\n\
89	subne	%2, %2, #1		@ without destroying	\n\
90	bne	1b			@ the carry flag	\n\
91	adcs	%0, %0, %3					\n\
92	adc	%0, %0, #0"
93	: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
94	: "1" (iph), "2" (ihl)
95	: "cc", "memory");
96	return csum_fold(sum);
97}
98
99static inline __wsum
100csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
101		   __u8 proto, __wsum sum)
102{
103	u32 lenprot = len + proto;
104	if (__builtin_constant_p(sum) && sum == 0) {
105		__asm__(
106		"adds	%0, %1, %2	@ csum_tcpudp_nofold0	\n\t"
107#ifdef __ARMEB__
108		"adcs	%0, %0, %3				\n\t"
109#else
110		"adcs	%0, %0, %3, ror #8			\n\t"
111#endif
112		"adc	%0, %0, #0"
113		: "=&r" (sum)
114		: "r" (daddr), "r" (saddr), "r" (lenprot)
115		: "cc");
116	} else {
117		__asm__(
118		"adds	%0, %1, %2	@ csum_tcpudp_nofold	\n\t"
119		"adcs	%0, %0, %3				\n\t"
120#ifdef __ARMEB__
121		"adcs	%0, %0, %4				\n\t"
122#else
123		"adcs	%0, %0, %4, ror #8			\n\t"
124#endif
125		"adc	%0, %0, #0"
126		: "=&r"(sum)
127		: "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot)
128		: "cc");
129	}
130	return sum;
131}
132/*
133 * computes the checksum of the TCP/UDP pseudo-header
134 * returns a 16-bit checksum, already complemented
135 */
136static inline __sum16
137csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
138		  __u8 proto, __wsum sum)
139{
140	return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
141}
142
143
144/*
145 * this routine is used for miscellaneous IP-like checksums, mainly
146 * in icmp.c
147 */
148static inline __sum16
149ip_compute_csum(const void *buff, int len)
150{
151	return csum_fold(csum_partial(buff, len, 0));
152}
153
154#define _HAVE_ARCH_IPV6_CSUM
155extern __wsum
156__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
157		__be32 proto, __wsum sum);
158
159static inline __sum16
160csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
161		__u32 len, __u8 proto, __wsum sum)
162{
163	return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
164					   htonl(proto), sum));
165}
166#endif
167