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 __wsum
  22 csum_partial_copy_from_user(const void __user *src, void *dst,
  23                             int len, __wsum 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, (const __u16 __user *)src);
  38                                 if (*errp)
  39                                         return isum;
  40                                 *(__u16 *)dst = val16;
  41                                 isum = (__force __wsum)add32_with_carry(
  42                                                 (__force unsigned)isum, val16);
  43                                 src += 2;
  44                                 dst += 2;
  45                                 len -= 2;
  46                         }
  47                 }
  48                 isum = csum_partial_copy_generic((__force const void *)src,
  49                                         dst, len, isum, errp, NULL);
  50                 if (likely(*errp == 0))
  51                         return isum;
  52         }
  53         *errp = -EFAULT;
  54         memset(dst,0,len);
  55         return isum;
  56 }
  57
  58 EXPORT_SYMBOL(csum_partial_copy_from_user);
  59
  60 /**
  61  * csum_partial_copy_to_user - Copy and checksum to user space.
  62  * @src: source address
  63  * @dst: destination address (user space)
  64  * @len: number of bytes to be copied.
  65  * @isum: initial sum that is added into the result (32bit unfolded)
  66  * @errp: set to -EFAULT for an bad destination address.
  67  *
  68  * Returns an 32bit unfolded checksum of the buffer.
  69  * src and dst are best aligned to 64bits.
  70  */
  71 __wsum
  72 csum_partial_copy_to_user(const void *src, void __user *dst,
  73                           int len, __wsum isum, int *errp)
  74 {
  75         might_sleep();
  76         if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
  77                 *errp = -EFAULT;
  78                 return 0;
  79         }
  80
  81         if (unlikely((unsigned long)dst & 6)) {
  82                 while (((unsigned long)dst & 6) && len >= 2) {
  83                         __u16 val16 = *(__u16 *)src;
  84                         isum = (__force __wsum)add32_with_carry(
  85                                         (__force unsigned)isum, val16);
  86                         *errp = __put_user(val16, (__u16 __user *)dst);
  87                         if (*errp)
  88                                 return isum;
  89                         src += 2;
  90                         dst += 2;
  91                         len -= 2;
  92                 }
  93         }
  94
  95         *errp = 0;
  96         return csum_partial_copy_generic(src, (void __force *)dst,len,isum,NULL,errp);
  97 }
  98
  99 EXPORT_SYMBOL(csum_partial_copy_to_user);
 100
 101 /**
 102  * csum_partial_copy_nocheck - Copy and checksum.
 103  * @src: source address
 104  * @dst: destination address
 105  * @len: number of bytes to be copied.
 106  * @isum: initial sum that is added into the result (32bit unfolded)
 107  *
 108  * Returns an 32bit unfolded checksum of the buffer.
 109  */
 110 __wsum
 111 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 112 {
 113         return csum_partial_copy_generic(src,dst,len,sum,NULL,NULL);
 114 }
 115 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 116
 117 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 118                         const struct in6_addr *daddr,
 119                         __u32 len, unsigned short proto, __wsum sum)
 120 {
 121         __u64 rest, sum64;
 122
 123         rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
 124                 (__force __u64)sum;
 125         asm("  addq (%[saddr]),%[sum]\n"
 126             "  adcq 8(%[saddr]),%[sum]\n"
 127             "  adcq (%[daddr]),%[sum]\n"
 128             "  adcq 8(%[daddr]),%[sum]\n"
 129             "  adcq $0,%[sum]\n"
 130             : [sum] "=r" (sum64)
 131             : "[sum]" (rest),[saddr] "r" (saddr), [daddr] "r" (daddr));
 132         return csum_fold((__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
 133 }
 134
 135 EXPORT_SYMBOL(csum_ipv6_magic);