1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __UM_CHECKSUM_H
3 #define __UM_CHECKSUM_H
4
5 #include <linux/string.h>
6 #include <linux/in6.h>
7 #include <linux/uaccess.h>
8
9 /*
10 * computes the checksum of a memory block at buff, length len,
11 * and adds in "sum" (32-bit)
12 *
13 * returns a 32-bit number suitable for feeding into itself
14 * or csum_tcpudp_magic
15 *
16 * this function must be called with even lengths, except
17 * for the last fragment, which may be odd
18 *
19 * it's best to have buff aligned on a 32-bit boundary
20 */
21 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
22
23 /*
24 * Note: when you get a NULL pointer exception here this means someone
25 * passed in an incorrect kernel address to one of these functions.
26 *
27 * If you use these functions directly please don't forget the
28 * access_ok().
29 */
30
31 static __inline__
32 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
33 int len, __wsum sum)
34 {
35 memcpy(dst, src, len);
36 return csum_partial(dst, len, sum);
37 }
38
39 /*
40 * the same as csum_partial, but copies from src while it
41 * checksums, and handles user-space pointer exceptions correctly, when needed.
42 *
43 * here even more important to align src and dst on a 32-bit (or even
44 * better 64-bit) boundary
45 */
46
47 static __inline__
48 __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
49 int len, __wsum sum, int *err_ptr)
50 {
51 if (copy_from_user(dst, src, len)) {
52 *err_ptr = -EFAULT;
53 return (__force __wsum)-1;
54 }
55
56 return csum_partial(dst, len, sum);
57 }
58
59 /**
60 * csum_fold - Fold and invert a 32bit checksum.
61 * sum: 32bit unfolded sum
62 *
63 * Fold a 32bit running checksum to 16bit and invert it. This is usually
64 * the last step before putting a checksum into a packet.
65 * Make sure not to mix with 64bit checksums.
66 */
67 static inline __sum16 csum_fold(__wsum sum)
68 {
69 __asm__(
70 " addl %1,%0\n"
71 " adcl $0xffff,%0"
72 : "=r" (sum)
73 : "r" ((__force u32)sum << 16),
74 "0" ((__force u32)sum & 0xffff0000)
75 );
76 return (__force __sum16)(~(__force u32)sum >> 16);
77 }
78
79 /**
80 * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
81 * @saddr: source address
82 * @daddr: destination address
83 * @len: length of packet
84 * @proto: ip protocol of packet
85 * @sum: initial sum to be added in (32bit unfolded)
86 *
87 * Returns the pseudo header checksum the input data. Result is
88 * 32bit unfolded.
89 */
90 static inline __wsum
91 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
92 __u8 proto, __wsum sum)
93 {
94 asm(" addl %1, %0\n"
95 " adcl %2, %0\n"
96 " adcl %3, %0\n"
97 " adcl $0, %0\n"
98 : "=r" (sum)
99 : "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum));
100 return sum;
101 }
102
103 /*
104 * computes the checksum of the TCP/UDP pseudo-header
105 * returns a 16-bit checksum, already complemented
106 */
107 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
108 __u32 len, __u8 proto,
109 __wsum sum)
110 {
111 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
112 }
113
114 /**
115 * ip_fast_csum - Compute the IPv4 header checksum efficiently.
116 * iph: ipv4 header
117 * ihl: length of header / 4
118 */
119 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
120 {
121 unsigned int sum;
122
123 asm( " movl (%1), %0\n"
124 " subl $4, %2\n"
125 " jbe 2f\n"
126 " addl 4(%1), %0\n"
127 " adcl 8(%1), %0\n"
128 " adcl 12(%1), %0\n"
129 "1: adcl 16(%1), %0\n"
130 " lea 4(%1), %1\n"
131 " decl %2\n"
132 " jne 1b\n"
133 " adcl $0, %0\n"
134 " movl %0, %2\n"
135 " shrl $16, %0\n"
136 " addw %w2, %w0\n"
137 " adcl $0, %0\n"
138 " notl %0\n"
139 "2:"
140 /* Since the input registers which are loaded with iph and ipl
141 are modified, we must also specify them as outputs, or gcc
142 will assume they contain their original values. */
143 : "=r" (sum), "=r" (iph), "=r" (ihl)
144 : "1" (iph), "2" (ihl)
145 : "memory");
146 return (__force __sum16)sum;
147 }
148
149 #ifdef CONFIG_X86_32
150 # include "checksum_32.h"
151 #else
152 # include "checksum_64.h"
153 #endif
154
155 #endif