1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_CHECKSUM_32_H
3 #define _ASM_X86_CHECKSUM_32_H
4
5 #include <linux/in6.h>
6 #include <linux/uaccess.h>
7
8 /*
9 * computes the checksum of a memory block at buff, length len,
10 * and adds in "sum" (32-bit)
11 *
12 * returns a 32-bit number suitable for feeding into itself
13 * or csum_tcpudp_magic
14 *
15 * this function must be called with even lengths, except
16 * for the last fragment, which may be odd
17 *
18 * it's best to have buff aligned on a 32-bit boundary
19 */
20 asmlinkage __wsum csum_partial(const void *buff, int len, __wsum sum);
21
22 /*
23 * the same as csum_partial, but copies from src while it
24 * checksums, and handles user-space pointer exceptions correctly, when needed.
25 *
26 * here even more important to align src and dst on a 32-bit (or even
27 * better 64-bit) boundary
28 */
29
30 asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst, int len);
31
32 /*
33 * Note: when you get a NULL pointer exception here this means someone
34 * passed in an incorrect kernel address to one of these functions.
35 *
36 * If you use these functions directly please don't forget the
37 * access_ok().
38 */
39 static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len)
40 {
41 return csum_partial_copy_generic(src, dst, len);
42 }
43
44 static inline __wsum csum_and_copy_from_user(const void __user *src,
45 void *dst, int len)
46 {
47 __wsum ret;
48
49 might_sleep();
50 if (!user_access_begin(src, len))
51 return 0;
52 ret = csum_partial_copy_generic((__force void *)src, dst, len);
53 user_access_end();
54
55 return ret;
56 }
57
58 /*
59 * This is a version of ip_compute_csum() optimized for IP headers,
60 * which always checksum on 4 octet boundaries.
61 *
62 * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
63 * Arnt Gulbrandsen.
64 */
65 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
66 {
67 unsigned int sum;
68
69 asm volatile("movl (%1), %0 ;\n"
70 "subl $4, %2 ;\n"
71 "jbe 2f ;\n"
72 "addl 4(%1), %0 ;\n"
73 "adcl 8(%1), %0 ;\n"
74 "adcl 12(%1), %0;\n"
75 "1: adcl 16(%1), %0 ;\n"
76 "lea 4(%1), %1 ;\n"
77 "decl %2 ;\n"
78 "jne 1b ;\n"
79 "adcl $0, %0 ;\n"
80 "movl %0, %2 ;\n"
81 "shrl $16, %0 ;\n"
82 "addw %w2, %w0 ;\n"
83 "adcl $0, %0 ;\n"
84 "notl %0 ;\n"
85 "2: ;\n"
86 /* Since the input registers which are loaded with iph and ihl
87 are modified, we must also specify them as outputs, or gcc
88 will assume they contain their original values. */
89 : "=r" (sum), "=r" (iph), "=r" (ihl)
90 : "1" (iph), "2" (ihl)
91 : "memory");
92 return (__force __sum16)sum;
93 }
94
95 /*
96 * Fold a partial checksum
97 */
98
99 static inline __sum16 csum_fold(__wsum sum)
100 {
101 asm("addl %1, %0 ;\n"
102 "adcl $0xffff, %0 ;\n"
103 : "=r" (sum)
104 : "r" ((__force u32)sum << 16),
105 "" ((__force u32)sum & 0xffff0000));
106 return (__force __sum16)(~(__force u32)sum >> 16);
107 }
108
109 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
110 __u32 len, __u8 proto,
111 __wsum sum)
112 {
113 asm("addl %1, %0 ;\n"
114 "adcl %2, %0 ;\n"
115 "adcl %3, %0 ;\n"
116 "adcl $0, %0 ;\n"
117 : "=r" (sum)
118 : "g" (daddr), "g"(saddr),
119 "g" ((len + proto) << 8), "" (sum));
120 return sum;
121 }
122
123 /*
124 * computes the checksum of the TCP/UDP pseudo-header
125 * returns a 16-bit checksum, already complemented
126 */
127 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
128 __u32 len, __u8 proto,
129 __wsum sum)
130 {
131 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
132 }
133
134 /*
135 * this routine is used for miscellaneous IP-like checksums, mainly
136 * in icmp.c
137 */
138
139 static inline __sum16 ip_compute_csum(const void *buff, int len)
140 {
141 return csum_fold(csum_partial(buff, len, 0));
142 }
143
144 #define _HAVE_ARCH_IPV6_CSUM
145 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
146 const struct in6_addr *daddr,
147 __u32 len, __u8 proto, __wsum sum)
148 {
149 asm("addl 0(%1), %0 ;\n"
150 "adcl 4(%1), %0 ;\n"
151 "adcl 8(%1), %0 ;\n"
152 "adcl 12(%1), %0 ;\n"
153 "adcl 0(%2), %0 ;\n"
154 "adcl 4(%2), %0 ;\n"
155 "adcl 8(%2), %0 ;\n"
156 "adcl 12(%2), %0 ;\n"
157 "adcl %3, %0 ;\n"
158 "adcl %4, %0 ;\n"
159 "adcl $0, %0 ;\n"
160 : "=&r" (sum)
161 : "r" (saddr), "r" (daddr),
162 "r" (htonl(len)), "r" (htonl(proto)), "" (sum)
163 : "memory");
164
165 return csum_fold(sum);
166 }
167
168 /*
169 * Copy and checksum to user
170 */
171 static inline __wsum csum_and_copy_to_user(const void *src,
172 void __user *dst,
173 int len)
174 {
175 __wsum ret;
176
177 might_sleep();
178 if (!user_access_begin(dst, len))
179 return 0;
180
181 ret = csum_partial_copy_generic(src, (__force void *)dst, len);
182 user_access_end();
183 return ret;
184 }
185
186 #endif /* _ASM_X86_CHECKSUM_32_H */
187
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