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
39 csum_partial_copy_nocheck(const void *src, void *dst, int len);
40
41 __wsum
42 csum_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
46 static 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 */
58 static 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 */
72 static inline __sum16
73 ip_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\
86 1: 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
99 static inline __wsum
100 csum_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 */
136 static inline __sum16
137 csum_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 */
148 static inline __sum16
149 ip_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
155 extern __wsum
156 __csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
157 __be32 proto, __wsum sum);
158
159 static inline __sum16
160 csum_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
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