arch/sh/lib64/c-checksum.c

   1 /*
   2  * arch/sh/lib64/c-checksum.c
   3  *
   4  * This file contains network checksum routines that are better done
   5  * in an architecture-specific manner due to speed..
   6  */
   7 #include <linux/string.h>
   8 #include <linux/errno.h>
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <asm/byteorder.h>
  12 #include <asm/uaccess.h>
  13
  14 static inline unsigned short from64to16(unsigned long long x)
  15 {
  16         /* add up 32-bit words for 33 bits */
  17         x = (x & 0xffffffff) + (x >> 32);
  18         /* add up 16-bit and 17-bit words for 17+c bits */
  19         x = (x & 0xffff) + (x >> 16);
  20         /* add up 16-bit and 2-bit for 16+c bit */
  21         x = (x & 0xffff) + (x >> 16);
  22         /* add up carry.. */
  23         x = (x & 0xffff) + (x >> 16);
  24         return x;
  25 }
  26
  27 static inline unsigned short foldto16(unsigned long x)
  28 {
  29         /* add up 16-bit for 17 bits */
  30         x = (x & 0xffff) + (x >> 16);
  31         /* add up carry.. */
  32         x = (x & 0xffff) + (x >> 16);
  33         return x;
  34 }
  35
  36 static inline unsigned short myfoldto16(unsigned long long x)
  37 {
  38         /* Fold down to 32-bits so we don't loose in the typedef-less
  39            network stack.  */
  40         /* 64 to 33 */
  41         x = (x & 0xffffffff) + (x >> 32);
  42         /* 33 to 32 */
  43         x = (x & 0xffffffff) + (x >> 32);
  44
  45         /* add up 16-bit for 17 bits */
  46         x = (x & 0xffff) + (x >> 16);
  47         /* add up carry.. */
  48         x = (x & 0xffff) + (x >> 16);
  49         return x;
  50 }
  51
  52 #define odd(x) ((x)&1)
  53 #define U16(x) ntohs(x)
  54
  55 static unsigned long do_csum(const unsigned char *buff, int len)
  56 {
  57         int odd, count;
  58         unsigned long result = 0;
  59
  60         pr_debug("do_csum buff %p, len %d (0x%x)\n", buff, len, len);
  61 #ifdef DEBUG
  62         for (i = 0; i < len; i++) {
  63                 if ((i % 26) == 0)
  64                         printk("\n");
  65                 printk("%02X ", buff[i]);
  66         }
  67 #endif
  68
  69         if (len <= 0)
  70                 goto out;
  71
  72         odd = 1 & (unsigned long) buff;
  73         if (odd) {
  74                 result = *buff << 8;
  75                 len--;
  76                 buff++;
  77         }
  78         count = len >> 1;       /* nr of 16-bit words.. */
  79         if (count) {
  80                 if (2 & (unsigned long) buff) {
  81                         result += *(unsigned short *) buff;
  82                         count--;
  83                         len -= 2;
  84                         buff += 2;
  85                 }
  86                 count >>= 1;    /* nr of 32-bit words.. */
  87                 if (count) {
  88                         unsigned long carry = 0;
  89                         do {
  90                                 unsigned long w = *(unsigned long *) buff;
  91                                 buff += 4;
  92                                 count--;
  93                                 result += carry;
  94                                 result += w;
  95                                 carry = (w > result);
  96                         } while (count);
  97                         result += carry;
  98                         result = (result & 0xffff) + (result >> 16);
  99                 }
 100                 if (len & 2) {
 101                         result += *(unsigned short *) buff;
 102                         buff += 2;
 103                 }
 104         }
 105         if (len & 1)
 106                 result += *buff;
 107         result = foldto16(result);
 108         if (odd)
 109                 result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
 110
 111         pr_debug("\nCHECKSUM is 0x%lx\n", result);
 112
 113       out:
 114         return result;
 115 }
 116
 117 /* computes the checksum of a memory block at buff, length len,
 118    and adds in "sum" (32-bit)  */
 119 __wsum csum_partial(const void *buff, int len, __wsum sum)
 120 {
 121         unsigned long long result = do_csum(buff, len);
 122
 123         /* add in old sum, and carry.. */
 124         result += (__force u32)sum;
 125         /* 32+c bits -> 32 bits */
 126         result = (result & 0xffffffff) + (result >> 32);
 127
 128         pr_debug("csum_partial, buff %p len %d sum 0x%x result=0x%016Lx\n",
 129                 buff, len, sum, result);
 130
 131         return (__force __wsum)result;
 132 }
 133
 134 /* Copy while checksumming, otherwise like csum_partial.  */
 135 __wsum
 136 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 137 {
 138         sum = csum_partial(src, len, sum);
 139         memcpy(dst, src, len);
 140
 141         return sum;
 142 }
 143
 144 /* Copy from userspace and compute checksum.  If we catch an exception
 145    then zero the rest of the buffer.  */
 146 __wsum
 147 csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 148                             __wsum sum, int *err_ptr)
 149 {
 150         int missing;
 151
 152         pr_debug
 153             ("csum_partial_copy_from_user src %p, dest %p, len %d, sum %08x, err_ptr %p\n",
 154              src, dst, len, sum, err_ptr);
 155         missing = copy_from_user(dst, src, len);
 156         pr_debug("  access_ok %d\n", __access_ok((unsigned long) src, len));
 157         pr_debug("  missing %d\n", missing);
 158         if (missing) {
 159                 memset(dst + len - missing, 0, missing);
 160                 *err_ptr = -EFAULT;
 161         }
 162
 163         return csum_partial(dst, len, sum);
 164 }
 165
 166 /* Copy to userspace and compute checksum.  */
 167 __wsum
 168 csum_partial_copy_to_user(const unsigned char *src, unsigned char *dst, int len,
 169                           __wsum sum, int *err_ptr)
 170 {
 171         sum = csum_partial(src, len, sum);
 172
 173         if (copy_to_user(dst, src, len))
 174                 *err_ptr = -EFAULT;
 175
 176         return sum;
 177 }
 178
 179 /*
 180  *      This is a version of ip_compute_csum() optimized for IP headers,
 181  *      which always checksum on 4 octet boundaries.
 182  */
 183 __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
 184 {
 185         pr_debug("ip_fast_csum %p,%d\n", iph, ihl);
 186
 187         return (__force __sum16)~do_csum(iph, ihl * 4);
 188 }
 189
 190 __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 191                                 unsigned short len,
 192                                 unsigned short proto, __wsum sum)
 193 {
 194         unsigned long long result;
 195
 196         pr_debug("ntohs(0x%x)=0x%x\n", 0xdead, ntohs(0xdead));
 197         pr_debug("htons(0x%x)=0x%x\n", 0xdead, htons(0xdead));
 198
 199         result = (__force u64) saddr + (__force u64) daddr +
 200                  (__force u64) sum + ((len + proto) << 8);
 201
 202         /* Fold down to 32-bits so we don't loose in the typedef-less
 203            network stack.  */
 204         /* 64 to 33 */
 205         result = (result & 0xffffffff) + (result >> 32);
 206         /* 33 to 32 */
 207         result = (result & 0xffffffff) + (result >> 32);
 208
 209         pr_debug("%s saddr %x daddr %x len %x proto %x sum %x result %08Lx\n",
 210                 __func__, saddr, daddr, len, proto, sum, result);
 211
 212         return (__wsum)result;
 213 }
 214 EXPORT_SYMBOL(csum_tcpudp_nofold);