Thomas Gleixner | 2874c5f | 2019-05-27 08:55:01 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 2 | /* |
| 3 | * |
| 4 | * INET An implementation of the TCP/IP protocol suite for the LINUX |
| 5 | * operating system. INET is implemented using the BSD Socket |
| 6 | * interface as the means of communication with the user level. |
| 7 | * |
| 8 | * IP/TCP/UDP checksumming routines |
| 9 | * |
| 10 | * Authors: Jorge Cwik, <jorge@laser.satlink.net> |
| 11 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| 12 | * Tom May, <ftom@netcom.com> |
| 13 | * Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de> |
| 14 | * Lots of code moved from tcp.c and ip.c; see those files |
| 15 | * for more names. |
| 16 | * |
| 17 | * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek: |
| 18 | * Fixed some nasty bugs, causing some horrible crashes. |
| 19 | * A: At some points, the sum (%0) was used as |
| 20 | * length-counter instead of the length counter |
| 21 | * (%1). Thanks to Roman Hodek for pointing this out. |
| 22 | * B: GCC seems to mess up if one uses too many |
| 23 | * data-registers to hold input values and one tries to |
| 24 | * specify d0 and d1 as scratch registers. Letting gcc |
| 25 | * choose these registers itself solves the problem. |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 26 | */ |
| 27 | |
| 28 | /* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access |
| 29 | kills, so most of the assembly has to go. */ |
| 30 | |
Paul Gortmaker | 8bc3bcc | 2011-11-16 21:29:17 -0500 | [diff] [blame] | 31 | #include <linux/export.h> |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 32 | #include <net/checksum.h> |
| 33 | |
| 34 | #include <asm/byteorder.h> |
| 35 | |
Arnd Bergmann | 20c1f64 | 2009-06-23 21:37:26 +0200 | [diff] [blame] | 36 | #ifndef do_csum |
Arnd Bergmann | c44ba9f | 2009-06-23 21:22:58 +0200 | [diff] [blame] | 37 | static inline unsigned short from32to16(unsigned int x) |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 38 | { |
| 39 | /* add up 16-bit and 16-bit for 16+c bit */ |
| 40 | x = (x & 0xffff) + (x >> 16); |
| 41 | /* add up carry.. */ |
| 42 | x = (x & 0xffff) + (x >> 16); |
| 43 | return x; |
| 44 | } |
| 45 | |
| 46 | static unsigned int do_csum(const unsigned char *buff, int len) |
| 47 | { |
Ian Abbott | be0e1e7 | 2011-07-07 01:18:49 +0000 | [diff] [blame] | 48 | int odd; |
Arnd Bergmann | c44ba9f | 2009-06-23 21:22:58 +0200 | [diff] [blame] | 49 | unsigned int result = 0; |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 50 | |
| 51 | if (len <= 0) |
| 52 | goto out; |
| 53 | odd = 1 & (unsigned long) buff; |
| 54 | if (odd) { |
Arnd Bergmann | 32a9ff9 | 2009-06-19 10:41:19 +0200 | [diff] [blame] | 55 | #ifdef __LITTLE_ENDIAN |
Arnd Bergmann | 32a9ff9 | 2009-06-19 10:41:19 +0200 | [diff] [blame] | 56 | result += (*buff << 8); |
Arnd Bergmann | 0a5549e | 2009-06-23 22:52:51 +0200 | [diff] [blame] | 57 | #else |
| 58 | result = *buff; |
Arnd Bergmann | 32a9ff9 | 2009-06-19 10:41:19 +0200 | [diff] [blame] | 59 | #endif |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 60 | len--; |
| 61 | buff++; |
| 62 | } |
Ian Abbott | be0e1e7 | 2011-07-07 01:18:49 +0000 | [diff] [blame] | 63 | if (len >= 2) { |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 64 | if (2 & (unsigned long) buff) { |
| 65 | result += *(unsigned short *) buff; |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 66 | len -= 2; |
| 67 | buff += 2; |
| 68 | } |
Ian Abbott | be0e1e7 | 2011-07-07 01:18:49 +0000 | [diff] [blame] | 69 | if (len >= 4) { |
| 70 | const unsigned char *end = buff + ((unsigned)len & ~3); |
Arnd Bergmann | c44ba9f | 2009-06-23 21:22:58 +0200 | [diff] [blame] | 71 | unsigned int carry = 0; |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 72 | do { |
Arnd Bergmann | c44ba9f | 2009-06-23 21:22:58 +0200 | [diff] [blame] | 73 | unsigned int w = *(unsigned int *) buff; |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 74 | buff += 4; |
| 75 | result += carry; |
| 76 | result += w; |
| 77 | carry = (w > result); |
Ian Abbott | be0e1e7 | 2011-07-07 01:18:49 +0000 | [diff] [blame] | 78 | } while (buff < end); |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 79 | result += carry; |
| 80 | result = (result & 0xffff) + (result >> 16); |
| 81 | } |
| 82 | if (len & 2) { |
| 83 | result += *(unsigned short *) buff; |
| 84 | buff += 2; |
| 85 | } |
| 86 | } |
| 87 | if (len & 1) |
Arnd Bergmann | 32a9ff9 | 2009-06-19 10:41:19 +0200 | [diff] [blame] | 88 | #ifdef __LITTLE_ENDIAN |
| 89 | result += *buff; |
| 90 | #else |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 91 | result += (*buff << 8); |
Arnd Bergmann | 32a9ff9 | 2009-06-19 10:41:19 +0200 | [diff] [blame] | 92 | #endif |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 93 | result = from32to16(result); |
| 94 | if (odd) |
| 95 | result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); |
| 96 | out: |
| 97 | return result; |
| 98 | } |
Arnd Bergmann | 20c1f64 | 2009-06-23 21:37:26 +0200 | [diff] [blame] | 99 | #endif |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 100 | |
Vineet Gupta | 64e6907 | 2013-01-18 15:12:16 +0530 | [diff] [blame] | 101 | #ifndef ip_fast_csum |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 102 | /* |
| 103 | * This is a version of ip_compute_csum() optimized for IP headers, |
| 104 | * which always checksum on 4 octet boundaries. |
| 105 | */ |
| 106 | __sum16 ip_fast_csum(const void *iph, unsigned int ihl) |
| 107 | { |
| 108 | return (__force __sum16)~do_csum(iph, ihl*4); |
| 109 | } |
| 110 | EXPORT_SYMBOL(ip_fast_csum); |
Vineet Gupta | 64e6907 | 2013-01-18 15:12:16 +0530 | [diff] [blame] | 111 | #endif |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 112 | |
| 113 | /* |
| 114 | * computes the checksum of a memory block at buff, length len, |
| 115 | * and adds in "sum" (32-bit) |
| 116 | * |
| 117 | * returns a 32-bit number suitable for feeding into itself |
| 118 | * or csum_tcpudp_magic |
| 119 | * |
| 120 | * this function must be called with even lengths, except |
| 121 | * for the last fragment, which may be odd |
| 122 | * |
| 123 | * it's best to have buff aligned on a 32-bit boundary |
| 124 | */ |
| 125 | __wsum csum_partial(const void *buff, int len, __wsum wsum) |
| 126 | { |
| 127 | unsigned int sum = (__force unsigned int)wsum; |
| 128 | unsigned int result = do_csum(buff, len); |
| 129 | |
| 130 | /* add in old sum, and carry.. */ |
| 131 | result += sum; |
| 132 | if (sum > result) |
| 133 | result += 1; |
| 134 | return (__force __wsum)result; |
| 135 | } |
| 136 | EXPORT_SYMBOL(csum_partial); |
| 137 | |
| 138 | /* |
| 139 | * this routine is used for miscellaneous IP-like checksums, mainly |
| 140 | * in icmp.c |
| 141 | */ |
| 142 | __sum16 ip_compute_csum(const void *buff, int len) |
| 143 | { |
| 144 | return (__force __sum16)~do_csum(buff, len); |
| 145 | } |
| 146 | EXPORT_SYMBOL(ip_compute_csum); |
| 147 | |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 148 | #ifndef csum_tcpudp_nofold |
karl beldan | 9ce3577 | 2015-01-29 11:10:22 +0100 | [diff] [blame] | 149 | static inline u32 from64to32(u64 x) |
| 150 | { |
| 151 | /* add up 32-bit and 32-bit for 32+c bit */ |
| 152 | x = (x & 0xffffffff) + (x >> 32); |
| 153 | /* add up carry.. */ |
| 154 | x = (x & 0xffffffff) + (x >> 32); |
| 155 | return (u32)x; |
| 156 | } |
| 157 | |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 158 | __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, |
Alexander Duyck | 01cfbad | 2016-03-11 14:05:34 -0800 | [diff] [blame] | 159 | __u32 len, __u8 proto, __wsum sum) |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 160 | { |
| 161 | unsigned long long s = (__force u32)sum; |
| 162 | |
| 163 | s += (__force u32)saddr; |
| 164 | s += (__force u32)daddr; |
| 165 | #ifdef __BIG_ENDIAN |
| 166 | s += proto + len; |
| 167 | #else |
| 168 | s += (proto + len) << 8; |
| 169 | #endif |
karl beldan | 150ae0e | 2015-01-28 10:58:11 +0100 | [diff] [blame] | 170 | return (__force __wsum)from64to32(s); |
Arnd Bergmann | 26a28fa | 2009-05-13 22:56:38 +0000 | [diff] [blame] | 171 | } |
| 172 | EXPORT_SYMBOL(csum_tcpudp_nofold); |
| 173 | #endif |