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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 | /* * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * MIPS specific IP/TCP/UDP checksumming routines * * Authors: Ralf Baechle, <ralf@waldorf-gmbh.de> * Lots of code moved from tcp.c and ip.c; see those files * for more names. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/module.h> #include <linux/types.h> #include <net/checksum.h> #include <asm/byteorder.h> #include <asm/string.h> #include <linux/uaccess.h> #define addc(_t,_r) \ __asm__ __volatile__ ( \ " add %0, %1, %0\n" \ " addc %0, %%r0, %0\n" \ : "=r"(_t) \ : "r"(_r), "0"(_t)); static inline unsigned short from32to16(unsigned int x) { /* 32 bits --> 16 bits + carry */ x = (x & 0xffff) + (x >> 16); /* 16 bits + carry --> 16 bits including carry */ x = (x & 0xffff) + (x >> 16); return (unsigned short)x; } static inline unsigned int do_csum(const unsigned char * buff, int len) { int odd, count; unsigned int result = 0; if (len <= 0) goto out; odd = 1 & (unsigned long) buff; if (odd) { result = be16_to_cpu(*buff); len--; buff++; } count = len >> 1; /* nr of 16-bit words.. */ if (count) { if (2 & (unsigned long) buff) { result += *(unsigned short *) buff; count--; len -= 2; buff += 2; } count >>= 1; /* nr of 32-bit words.. */ if (count) { while (count >= 4) { unsigned int r1, r2, r3, r4; r1 = *(unsigned int *)(buff + 0); r2 = *(unsigned int *)(buff + 4); r3 = *(unsigned int *)(buff + 8); r4 = *(unsigned int *)(buff + 12); addc(result, r1); addc(result, r2); addc(result, r3); addc(result, r4); count -= 4; buff += 16; } while (count) { unsigned int w = *(unsigned int *) buff; count--; buff += 4; addc(result, w); } result = (result & 0xffff) + (result >> 16); } if (len & 2) { result += *(unsigned short *) buff; buff += 2; } } if (len & 1) result += le16_to_cpu(*buff); result = from32to16(result); if (odd) result = swab16(result); out: return result; } /* * computes a partial checksum, e.g. for TCP/UDP fragments */ /* * why bother folding? */ __wsum csum_partial(const void *buff, int len, __wsum sum) { unsigned int result = do_csum(buff, len); addc(result, sum); return (__force __wsum)from32to16(result); } EXPORT_SYMBOL(csum_partial); /* * copy while checksumming, otherwise like csum_partial */ __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum) { /* * It's 2:30 am and I don't feel like doing it real ... * This is lots slower than the real thing (tm) */ sum = csum_partial(src, len, sum); memcpy(dst, src, len); return sum; } EXPORT_SYMBOL(csum_partial_copy_nocheck); /* * Copy from userspace and compute checksum. If we catch an exception * then zero the rest of the buffer. */ __wsum csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr) { int missing; missing = copy_from_user(dst, src, len); if (missing) { memset(dst + len - missing, 0, missing); *err_ptr = -EFAULT; } return csum_partial(dst, len, sum); } EXPORT_SYMBOL(csum_partial_copy_from_user); |