arch/x86_64/lib/csum-wrappers.c

   1 /* Copyright 2002,2003 Andi Kleen, SuSE Labs.
   2  * Subject to the GNU Public License v.2
   3  *
   4  * Wrappers of assembly checksum functions for x86-64.
   5  */
   6
   7 #include <asm/checksum.h>
   8 #include <linux/module.h>
   9
  10 /**
  11  * csum_partial_copy_from_user - Copy and checksum from user space.
  12  * @src: source address (user space)
  13  * @dst: destination address
  14  * @len: number of bytes to be copied.
  15  * @isum: initial sum that is added into the result (32bit unfolded)
  16  * @errp: set to -EFAULT for an bad source address.
  17  *
  18  * Returns an 32bit unfolded checksum of the buffer.
  19  * src and dst are best aligned to 64bits.
  20  */
  21 unsigned int
  22 csum_partial_copy_from_user(const unsigned char __user *src, unsigned char *dst,
  23                             int len, unsigned int isum, int *errp)
  24 {
  25         might_sleep();
  26         *errp = 0;
  27         if (likely(access_ok(VERIFY_READ,src, len))) {
  28                 /* Why 6, not 7? To handle odd addresses aligned we
  29                    would need to do considerable complications to fix the
  30                    checksum which is defined as an 16bit accumulator. The
  31                    fix alignment code is primarily for performance
  32                    compatibility with 32bit and that will handle odd
  33                    addresses slowly too. */
  34                 if (unlikely((unsigned long)src & 6)) {
  35                         while (((unsigned long)src & 6) && len >= 2) {
  36                                 __u16 val16;
  37                                 *errp = __get_user(val16, (__u16 __user *)src);
  38                                 if (*errp)
  39                                         return isum;
  40                                 *(__u16 *)dst = val16;
  41                                 isum = add32_with_carry(isum, val16);
  42                                 src += 2;
  43                                 dst += 2;
  44                                 len -= 2;
  45                         }
  46                 }
  47                 isum = csum_partial_copy_generic((__force void *)src,dst,len,isum,errp,NULL);
  48                 if (likely(*errp == 0))
  49                         return isum;
  50         }
  51         *errp = -EFAULT;
  52         memset(dst,0,len);
  53         return isum;
  54 }
  55
  56 EXPORT_SYMBOL(csum_partial_copy_from_user);
  57
  58 /**
  59  * csum_partial_copy_to_user - Copy and checksum to user space.
  60  * @src: source address
  61  * @dst: destination address (user space)
  62  * @len: number of bytes to be copied.
  63  * @isum: initial sum that is added into the result (32bit unfolded)
  64  * @errp: set to -EFAULT for an bad destination address.
  65  *
  66  * Returns an 32bit unfolded checksum of the buffer.
  67  * src and dst are best aligned to 64bits.
  68  */
  69 unsigned int
  70 csum_partial_copy_to_user(unsigned const char *src, unsigned char __user *dst,
  71                           int len, unsigned int isum, int *errp)
  72 {
  73         might_sleep();
  74         if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
  75                 *errp = -EFAULT;
  76                 return 0;
  77         }
  78
  79         if (unlikely((unsigned long)dst & 6)) {
  80                 while (((unsigned long)dst & 6) && len >= 2) {
  81                         __u16 val16 = *(__u16 *)src;
  82                         isum = add32_with_carry(isum, val16);
  83                         *errp = __put_user(val16, (__u16 __user *)dst);
  84                         if (*errp)
  85                                 return isum;
  86                         src += 2;
  87                         dst += 2;
  88                         len -= 2;
  89                 }
  90         }
  91
  92         *errp = 0;
  93         return csum_partial_copy_generic(src, (void __force *)dst,len,isum,NULL,errp);
  94 }
  95
  96 EXPORT_SYMBOL(csum_partial_copy_to_user);
  97
  98 /**
  99  * csum_partial_copy_nocheck - Copy and checksum.
 100  * @src: source address
 101  * @dst: destination address
 102  * @len: number of bytes to be copied.
 103  * @isum: initial sum that is added into the result (32bit unfolded)
 104  *
 105  * Returns an 32bit unfolded checksum of the buffer.
 106  */
 107 unsigned int
 108 csum_partial_copy_nocheck(const unsigned char *src, unsigned char *dst, int len, unsigned int sum)
 109 {
 110         return csum_partial_copy_generic(src,dst,len,sum,NULL,NULL);
 111 }
 112 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 113
 114 unsigned short csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr,
 115                                __u32 len, unsigned short proto, unsigned int sum)
 116 {
 117         __u64 rest, sum64;
 118
 119         rest = (__u64)htonl(len) + (__u64)htons(proto) + (__u64)sum;
 120         asm("  addq (%[saddr]),%[sum]\n"
 121             "  adcq 8(%[saddr]),%[sum]\n"
 122             "  adcq (%[daddr]),%[sum]\n"
 123             "  adcq 8(%[daddr]),%[sum]\n"
 124             "  adcq $0,%[sum]\n"
 125             : [sum] "=r" (sum64)
 126             : "[sum]" (rest),[saddr] "r" (saddr), [daddr] "r" (daddr));
 127         return csum_fold(add32_with_carry(sum64 & 0xffffffff, sum64>>32));
 128 }
 129
 130 EXPORT_SYMBOL(csum_ipv6_magic);