root/arch/x86/lib/csum-wrappers_64.c

DEFINITIONS

1. csum_partial_copy_from_user
2. csum_partial_copy_to_user
3. csum_partial_copy_nocheck
4. csum_ipv6_magic

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2002, 2003 Andi Kleen, SuSE Labs.
   4  *
   5  * Wrappers of assembly checksum functions for x86-64.
   6  */
   7 #include <asm/checksum.h>
   8 #include <linux/export.h>
   9 #include <linux/uaccess.h>
  10 #include <asm/smap.h>
  11 
  12 /**
  13  * csum_partial_copy_from_user - Copy and checksum from user space.
  14  * @src: source address (user space)
  15  * @dst: destination address
  16  * @len: number of bytes to be copied.
  17  * @isum: initial sum that is added into the result (32bit unfolded)
  18  * @errp: set to -EFAULT for an bad source address.
  19  *
  20  * Returns an 32bit unfolded checksum of the buffer.
  21  * src and dst are best aligned to 64bits.
  22  */
  23 __wsum
  24 csum_partial_copy_from_user(const void __user *src, void *dst,
  25                             int len, __wsum isum, int *errp)
  26 {
  27         might_sleep();
  28         *errp = 0;
  29 
  30         if (!likely(access_ok(src, len)))
  31                 goto out_err;
  32 
  33         /*
  34          * Why 6, not 7? To handle odd addresses aligned we
  35          * would need to do considerable complications to fix the
  36          * checksum which is defined as an 16bit accumulator. The
  37          * fix alignment code is primarily for performance
  38          * compatibility with 32bit and that will handle odd
  39          * addresses slowly too.
  40          */
  41         if (unlikely((unsigned long)src & 6)) {
  42                 while (((unsigned long)src & 6) && len >= 2) {
  43                         __u16 val16;
  44 
  45                         if (__get_user(val16, (const __u16 __user *)src))
  46                                 goto out_err;
  47 
  48                         *(__u16 *)dst = val16;
  49                         isum = (__force __wsum)add32_with_carry(
  50                                         (__force unsigned)isum, val16);
  51                         src += 2;
  52                         dst += 2;
  53                         len -= 2;
  54                 }
  55         }
  56         stac();
  57         isum = csum_partial_copy_generic((__force const void *)src,
  58                                 dst, len, isum, errp, NULL);
  59         clac();
  60         if (unlikely(*errp))
  61                 goto out_err;
  62 
  63         return isum;
  64 
  65 out_err:
  66         *errp = -EFAULT;
  67         memset(dst, 0, len);
  68 
  69         return isum;
  70 }
  71 EXPORT_SYMBOL(csum_partial_copy_from_user);
  72 
  73 /**
  74  * csum_partial_copy_to_user - Copy and checksum to user space.
  75  * @src: source address
  76  * @dst: destination address (user space)
  77  * @len: number of bytes to be copied.
  78  * @isum: initial sum that is added into the result (32bit unfolded)
  79  * @errp: set to -EFAULT for an bad destination address.
  80  *
  81  * Returns an 32bit unfolded checksum of the buffer.
  82  * src and dst are best aligned to 64bits.
  83  */
  84 __wsum
  85 csum_partial_copy_to_user(const void *src, void __user *dst,
  86                           int len, __wsum isum, int *errp)
  87 {
  88         __wsum ret;
  89 
  90         might_sleep();
  91 
  92         if (unlikely(!access_ok(dst, len))) {
  93                 *errp = -EFAULT;
  94                 return 0;
  95         }
  96 
  97         if (unlikely((unsigned long)dst & 6)) {
  98                 while (((unsigned long)dst & 6) && len >= 2) {
  99                         __u16 val16 = *(__u16 *)src;
 100 
 101                         isum = (__force __wsum)add32_with_carry(
 102                                         (__force unsigned)isum, val16);
 103                         *errp = __put_user(val16, (__u16 __user *)dst);
 104                         if (*errp)
 105                                 return isum;
 106                         src += 2;
 107                         dst += 2;
 108                         len -= 2;
 109                 }
 110         }
 111 
 112         *errp = 0;
 113         stac();
 114         ret = csum_partial_copy_generic(src, (void __force *)dst,
 115                                         len, isum, NULL, errp);
 116         clac();
 117         return ret;
 118 }
 119 EXPORT_SYMBOL(csum_partial_copy_to_user);
 120 
 121 /**
 122  * csum_partial_copy_nocheck - Copy and checksum.
 123  * @src: source address
 124  * @dst: destination address
 125  * @len: number of bytes to be copied.
 126  * @sum: initial sum that is added into the result (32bit unfolded)
 127  *
 128  * Returns an 32bit unfolded checksum of the buffer.
 129  */
 130 __wsum
 131 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 132 {
 133         return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 134 }
 135 EXPORT_SYMBOL(csum_partial_copy_nocheck);
 136 
 137 __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 138                         const struct in6_addr *daddr,
 139                         __u32 len, __u8 proto, __wsum sum)
 140 {
 141         __u64 rest, sum64;
 142 
 143         rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
 144                 (__force __u64)sum;
 145 
 146         asm("   addq (%[saddr]),%[sum]\n"
 147             "   adcq 8(%[saddr]),%[sum]\n"
 148             "   adcq (%[daddr]),%[sum]\n"
 149             "   adcq 8(%[daddr]),%[sum]\n"
 150             "   adcq $0,%[sum]\n"
 151 
 152             : [sum] "=r" (sum64)
 153             : "[sum]" (rest), [saddr] "r" (saddr), [daddr] "r" (daddr));
 154 
 155         return csum_fold(
 156                (__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
 157 }
 158 EXPORT_SYMBOL(csum_ipv6_magic);