treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
[muen/linux.git] / arch / parisc / lib / checksum.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
4  *              operating system.  INET is implemented using the  BSD Socket
5  *              interface as the means of communication with the user level.
6  *
7  *              MIPS specific IP/TCP/UDP checksumming routines
8  *
9  * Authors:     Ralf Baechle, <ralf@waldorf-gmbh.de>
10  *              Lots of code moved from tcp.c and ip.c; see those files
11  *              for more names.
12  */
13 #include <linux/module.h>
14 #include <linux/types.h>
15
16 #include <net/checksum.h>
17 #include <asm/byteorder.h>
18 #include <asm/string.h>
19 #include <linux/uaccess.h>
20
21 #define addc(_t,_r)                     \
22         __asm__ __volatile__ (          \
23 "       add             %0, %1, %0\n"   \
24 "       addc            %0, %%r0, %0\n" \
25         : "=r"(_t)                      \
26         : "r"(_r), "0"(_t));
27
28 static inline unsigned short from32to16(unsigned int x)
29 {
30         /* 32 bits --> 16 bits + carry */
31         x = (x & 0xffff) + (x >> 16);
32         /* 16 bits + carry --> 16 bits including carry */
33         x = (x & 0xffff) + (x >> 16);
34         return (unsigned short)x;
35 }
36
37 static inline unsigned int do_csum(const unsigned char * buff, int len)
38 {
39         int odd, count;
40         unsigned int result = 0;
41
42         if (len <= 0)
43                 goto out;
44         odd = 1 & (unsigned long) buff;
45         if (odd) {
46                 result = be16_to_cpu(*buff);
47                 len--;
48                 buff++;
49         }
50         count = len >> 1;               /* nr of 16-bit words.. */
51         if (count) {
52                 if (2 & (unsigned long) buff) {
53                         result += *(unsigned short *) buff;
54                         count--;
55                         len -= 2;
56                         buff += 2;
57                 }
58                 count >>= 1;            /* nr of 32-bit words.. */
59                 if (count) {
60                         while (count >= 4) {
61                                 unsigned int r1, r2, r3, r4;
62                                 r1 = *(unsigned int *)(buff + 0);
63                                 r2 = *(unsigned int *)(buff + 4);
64                                 r3 = *(unsigned int *)(buff + 8);
65                                 r4 = *(unsigned int *)(buff + 12);
66                                 addc(result, r1);
67                                 addc(result, r2);
68                                 addc(result, r3);
69                                 addc(result, r4);
70                                 count -= 4;
71                                 buff += 16;
72                         }
73                         while (count) {
74                                 unsigned int w = *(unsigned int *) buff;
75                                 count--;
76                                 buff += 4;
77                                 addc(result, w);
78                         }
79                         result = (result & 0xffff) + (result >> 16);
80                 }
81                 if (len & 2) {
82                         result += *(unsigned short *) buff;
83                         buff += 2;
84                 }
85         }
86         if (len & 1)
87                 result += le16_to_cpu(*buff);
88         result = from32to16(result);
89         if (odd)
90                 result = swab16(result);
91 out:
92         return result;
93 }
94
95 /*
96  * computes a partial checksum, e.g. for TCP/UDP fragments
97  */
98 /*
99  * why bother folding?
100  */
101 __wsum csum_partial(const void *buff, int len, __wsum sum)
102 {
103         unsigned int result = do_csum(buff, len);
104         addc(result, sum);
105         return (__force __wsum)from32to16(result);
106 }
107
108 EXPORT_SYMBOL(csum_partial);
109
110 /*
111  * copy while checksumming, otherwise like csum_partial
112  */
113 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
114                                        int len, __wsum sum)
115 {
116         /*
117          * It's 2:30 am and I don't feel like doing it real ...
118          * This is lots slower than the real thing (tm)
119          */
120         sum = csum_partial(src, len, sum);
121         memcpy(dst, src, len);
122
123         return sum;
124 }
125 EXPORT_SYMBOL(csum_partial_copy_nocheck);
126
127 /*
128  * Copy from userspace and compute checksum.  If we catch an exception
129  * then zero the rest of the buffer.
130  */
131 __wsum csum_partial_copy_from_user(const void __user *src,
132                                         void *dst, int len,
133                                         __wsum sum, int *err_ptr)
134 {
135         int missing;
136
137         missing = copy_from_user(dst, src, len);
138         if (missing) {
139                 memset(dst + len - missing, 0, missing);
140                 *err_ptr = -EFAULT;
141         }
142                 
143         return csum_partial(dst, len, sum);
144 }
145 EXPORT_SYMBOL(csum_partial_copy_from_user);