kernel/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 #include <asm/smap.h>
  10
  11 /**
  12  * csum_partial_copy_from_user - Copy and checksum from user space.
  13  * @src: source address (user space)
  14  * @dst: destination address
  15  * @len: number of bytes to be copied.
  16  * @isum: initial sum that is added into the result (32bit unfolded)
  17  * @errp: set to -EFAULT for an bad source address.
  18  *
  19  * Returns an 32bit unfolded checksum of the buffer.
  20  * src and dst are best aligned to 64bits.
  21  */
  22 __wsum
  23 csum_partial_copy_from_user(const void __user *src, void *dst,
  24                             int len, __wsum isum, int *errp)
  25 {
  26         might_sleep();
  27         *errp = 0;
  28
  29         if (!likely(access_ok(VERIFY_READ, src, len)))
  30                 goto out_err;
  31
  32         /*
  33          * Why 6, not 7? To handle odd addresses aligned we
  34          * would need to do considerable complications to fix the
  35          * checksum which is defined as an 16bit accumulator. The
  36          * fix alignment code is primarily for performance
  37          * compatibility with 32bit and that will handle odd
  38          * addresses slowly too.
  39          */
  40         if (unlikely((unsigned long)src & 6)) {
  41                 while (((unsigned long)src & 6) && len >= 2) {
  42                         __u16 val16;
  43
  44                         if (__get_user(val16, (const __u16 __user *)src))
  45                                 goto out_err;
  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         stac();
  56         isum = csum_partial_copy_generic((__force const void *)src,
  57                                 dst, len, isum, errp, NULL);
  58         clac();
  59         if (unlikely(*errp))
  60                 goto out_err;
  61
  62         return isum;
  63
  64 out_err:
  65         *errp = -EFAULT;
  66         memset(dst, 0, len);
  67
  68         return isum;
  69 }
  70 EXPORT_SYMBOL(csum_partial_copy_from_user);
  71
  72 /**
  73  * csum_partial_copy_to_user - Copy and checksum to user space.
  74  * @src: source address
  75  * @dst: destination address (user space)
  76  * @len: number of bytes to be copied.
  77  * @isum: initial sum that is added into the result (32bit unfolded)
  78  * @errp: set to -EFAULT for an bad destination address.
  79  *
  80  * Returns an 32bit unfolded checksum of the buffer.
  81  * src and dst are best aligned to 64bits.
  82  */
  83 __wsum
  84 csum_partial_copy_to_user(const void *src, void __user *dst,
  85                           int len, __wsum isum, int *errp)
  86 {
  87         __wsum ret;
  88
  89         might_sleep();
  90
  91         if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
  92                 *errp = -EFAULT;
  93                 return 0;
  94         }
  95
  96         if (unlikely((unsigned long)dst & 6)) {
  97                 while (((unsigned long)dst & 6) && len >= 2) {
  98                         __u16 val16 = *(__u16 *)src;
  99
 100                         isum = (__force __wsum)add32_with_carry(
 101                                         (__force unsigned)isum, val16);
 102                         *errp = __put_user(val16, (__u16 __user *)dst);
 103                         if (*errp)
 104                                 return isum;
 105                         src += 2;
 106                         dst += 2;
 107                         len -= 2;
 108                 }
 109         }
 110
 111         *errp = 0;
 112         stac();
 113         ret = csum_partial_copy_generic(src, (void __force *)dst,
 114                                         len, isum, NULL, errp);
 115         clac();
 116         return ret;
 117 }
 118 EXPORT_SYMBOL(csum_partial_copy_to_user);
 119
 120 /**
 121  * csum_partial_copy_nocheck - Copy and checksum.
 122  * @src: source address
 123  * @dst: destination address
 124  * @len: number of bytes to be copied.
 125  * @sum: initial sum that is added into the result (32bit unfolded)
 126  *
 127  * Returns an 32bit unfolded checksum of the buffer.
 128  */
 129 __wsum
 130 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 131 {
 132         return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 133 }
 134 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 135
 136 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 137                         const struct in6_addr *daddr,
 138                         __u32 len, unsigned short proto, __wsum sum)
 139 {
 140         __u64 rest, sum64;
 141
 142         rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
 143                 (__force __u64)sum;
 144
 145         asm("   addq (%[saddr]),%[sum]\n"
 146             "   adcq 8(%[saddr]),%[sum]\n"
 147             "   adcq (%[daddr]),%[sum]\n"
 148             "   adcq 8(%[daddr]),%[sum]\n"
 149             "   adcq $0,%[sum]\n"
 150
 151             : [sum] "=r" (sum64)
 152             : "[sum]" (rest), [saddr] "r" (saddr), [daddr] "r" (daddr));
 153
 154         return csum_fold(
 155                (__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
 156 }
 157 EXPORT_SYMBOL(csum_ipv6_magic);