arch/x86/lib/csum-wrappers_64.c

   1 /*
   2  * Copyright 2002, 2003 Andi Kleen, SuSE Labs.
   3  * Subject to the GNU Public License v.2
   4  *
   5  * Wrappers of assembly checksum functions for x86-64.
   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
  28         if (!likely(access_ok(VERIFY_READ, src, len)))
  29                 goto out_err;
  30
  31         /*
  32          * Why 6, not 7? To handle odd addresses aligned we
  33          * would need to do considerable complications to fix the
  34          * checksum which is defined as an 16bit accumulator. The
  35          * fix alignment code is primarily for performance
  36          * compatibility with 32bit and that will handle odd
  37          * addresses slowly too.
  38          */
  39         if (unlikely((unsigned long)src & 6)) {
  40                 while (((unsigned long)src & 6) && len >= 2) {
  41                         __u16 val16;
  42
  43                         *errp = __get_user(val16, (const __u16 __user *)src);
  44                         if (*errp)
  45                                 return isum;
  46
  47                         *(__u16 *)dst = val16;
  48                         isum = (__force __wsum)add32_with_carry(
  49                                         (__force unsigned)isum, val16);
  50                         src += 2;
  51                         dst += 2;
  52                         len -= 2;
  53                 }
  54         }
  55         isum = csum_partial_copy_generic((__force const void *)src,
  56                                 dst, len, isum, errp, NULL);
  57         if (unlikely(*errp))
  58                 goto out_err;
  59
  60         return isum;
  61
  62 out_err:
  63         *errp = -EFAULT;
  64         memset(dst, 0, len);
  65
  66         return isum;
  67 }
  68 EXPORT_SYMBOL(csum_partial_copy_from_user);
  69
  70 /**
  71  * csum_partial_copy_to_user - Copy and checksum to user space.
  72  * @src: source address
  73  * @dst: destination address (user space)
  74  * @len: number of bytes to be copied.
  75  * @isum: initial sum that is added into the result (32bit unfolded)
  76  * @errp: set to -EFAULT for an bad destination address.
  77  *
  78  * Returns an 32bit unfolded checksum of the buffer.
  79  * src and dst are best aligned to 64bits.
  80  */
  81 __wsum
  82 csum_partial_copy_to_user(const void *src, void __user *dst,
  83                           int len, __wsum isum, int *errp)
  84 {
  85         might_sleep();
  86
  87         if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
  88                 *errp = -EFAULT;
  89                 return 0;
  90         }
  91
  92         if (unlikely((unsigned long)dst & 6)) {
  93                 while (((unsigned long)dst & 6) && len >= 2) {
  94                         __u16 val16 = *(__u16 *)src;
  95
  96                         isum = (__force __wsum)add32_with_carry(
  97                                         (__force unsigned)isum, val16);
  98                         *errp = __put_user(val16, (__u16 __user *)dst);
  99                         if (*errp)
 100                                 return isum;
 101                         src += 2;
 102                         dst += 2;
 103                         len -= 2;
 104                 }
 105         }
 106
 107         *errp = 0;
 108         return csum_partial_copy_generic(src, (void __force *)dst,
 109                                          len, isum, NULL, errp);
 110 }
 111 EXPORT_SYMBOL(csum_partial_copy_to_user);
 112
 113 /**
 114  * csum_partial_copy_nocheck - Copy and checksum.
 115  * @src: source address
 116  * @dst: destination address
 117  * @len: number of bytes to be copied.
 118  * @isum: initial sum that is added into the result (32bit unfolded)
 119  *
 120  * Returns an 32bit unfolded checksum of the buffer.
 121  */
 122 __wsum
 123 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 124 {
 125         return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 126 }
 127 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 128
 129 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 130                         const struct in6_addr *daddr,
 131                         __u32 len, unsigned short proto, __wsum sum)
 132 {
 133         __u64 rest, sum64;
 134
 135         rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
 136                 (__force __u64)sum;
 137
 138         asm("   addq (%[saddr]),%[sum]\n"
 139             "   adcq 8(%[saddr]),%[sum]\n"
 140             "   adcq (%[daddr]),%[sum]\n"
 141             "   adcq 8(%[daddr]),%[sum]\n"
 142             "   adcq $0,%[sum]\n"
 143
 144             : [sum] "=r" (sum64)
 145             : "[sum]" (rest), [saddr] "r" (saddr), [daddr] "r" (daddr));
 146
 147         return csum_fold(
 148                (__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
 149 }
 150 EXPORT_SYMBOL(csum_ipv6_magic);