arch/arm/include/asm/checksum.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *  arch/arm/include/asm/checksum.h
   4  *
   5  * IP checksum routines
   6  *
   7  * Copyright (C) Original authors of ../asm-i386/checksum.h
   8  * Copyright (C) 1996-1999 Russell King
   9  */
  10 #ifndef __ASM_ARM_CHECKSUM_H
  11 #define __ASM_ARM_CHECKSUM_H
  12
  13 #include <linux/in6.h>
  14
  15 /*
  16  * computes the checksum of a memory block at buff, length len,
  17  * and adds in "sum" (32-bit)
  18  *
  19  * returns a 32-bit number suitable for feeding into itself
  20  * or csum_tcpudp_magic
  21  *
  22  * this function must be called with even lengths, except
  23  * for the last fragment, which may be odd
  24  *
  25  * it's best to have buff aligned on a 32-bit boundary
  26  */
  27 __wsum csum_partial(const void *buff, int len, __wsum sum);
  28
  29 /*
  30  * the same as csum_partial, but copies from src while it
  31  * checksums, and handles user-space pointer exceptions correctly, when needed.
  32  *
  33  * here even more important to align src and dst on a 32-bit (or even
  34  * better 64-bit) boundary
  35  */
  36
  37 __wsum
  38 csum_partial_copy_nocheck(const void *src, void *dst, int len);
  39
  40 __wsum
  41 csum_partial_copy_from_user(const void __user *src, void *dst, int len);
  42
  43 #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
  44 #define _HAVE_ARCH_CSUM_AND_COPY
  45 static inline
  46 __wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
  47 {
  48         if (!access_ok(src, len))
  49                 return 0;
  50
  51         return csum_partial_copy_from_user(src, dst, len);
  52 }
  53
  54 /*
  55  *      Fold a partial checksum without adding pseudo headers
  56  */
  57 static inline __sum16 csum_fold(__wsum sum)
  58 {
  59         __asm__(
  60         "add    %0, %1, %1, ror #16     @ csum_fold"
  61         : "=r" (sum)
  62         : "r" (sum)
  63         : "cc");
  64         return (__force __sum16)(~(__force u32)sum >> 16);
  65 }
  66
  67 /*
  68  *      This is a version of ip_compute_csum() optimized for IP headers,
  69  *      which always checksum on 4 octet boundaries.
  70  */
  71 static inline __sum16
  72 ip_fast_csum(const void *iph, unsigned int ihl)
  73 {
  74         unsigned int tmp1;
  75         __wsum sum;
  76
  77         __asm__ __volatile__(
  78         "ldr    %0, [%1], #4            @ ip_fast_csum          \n\
  79         ldr     %3, [%1], #4                                    \n\
  80         sub     %2, %2, #5                                      \n\
  81         adds    %0, %0, %3                                      \n\
  82         ldr     %3, [%1], #4                                    \n\
  83         adcs    %0, %0, %3                                      \n\
  84         ldr     %3, [%1], #4                                    \n\
  85 1:      adcs    %0, %0, %3                                      \n\
  86         ldr     %3, [%1], #4                                    \n\
  87         tst     %2, #15                 @ do this carefully     \n\
  88         subne   %2, %2, #1              @ without destroying    \n\
  89         bne     1b                      @ the carry flag        \n\
  90         adcs    %0, %0, %3                                      \n\
  91         adc     %0, %0, #0"
  92         : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
  93         : "1" (iph), "2" (ihl)
  94         : "cc", "memory");
  95         return csum_fold(sum);
  96 }
  97
  98 static inline __wsum
  99 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
 100                    __u8 proto, __wsum sum)
 101 {
 102         u32 lenprot = len + proto;
 103         if (__builtin_constant_p(sum) && sum == 0) {
 104                 __asm__(
 105                 "adds   %0, %1, %2      @ csum_tcpudp_nofold0   \n\t"
 106 #ifdef __ARMEB__
 107                 "adcs   %0, %0, %3                              \n\t"
 108 #else
 109                 "adcs   %0, %0, %3, ror #8                      \n\t"
 110 #endif
 111                 "adc    %0, %0, #0"
 112                 : "=&r" (sum)
 113                 : "r" (daddr), "r" (saddr), "r" (lenprot)
 114                 : "cc");
 115         } else {
 116                 __asm__(
 117                 "adds   %0, %1, %2      @ csum_tcpudp_nofold    \n\t"
 118                 "adcs   %0, %0, %3                              \n\t"
 119 #ifdef __ARMEB__
 120                 "adcs   %0, %0, %4                              \n\t"
 121 #else
 122                 "adcs   %0, %0, %4, ror #8                      \n\t"
 123 #endif
 124                 "adc    %0, %0, #0"
 125                 : "=&r"(sum)
 126                 : "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot)
 127                 : "cc");
 128         }
 129         return sum;
 130 }
 131 /*
 132  * computes the checksum of the TCP/UDP pseudo-header
 133  * returns a 16-bit checksum, already complemented
 134  */
 135 static inline __sum16
 136 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
 137                   __u8 proto, __wsum sum)
 138 {
 139         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 140 }
 141
 142
 143 /*
 144  * this routine is used for miscellaneous IP-like checksums, mainly
 145  * in icmp.c
 146  */
 147 static inline __sum16
 148 ip_compute_csum(const void *buff, int len)
 149 {
 150         return csum_fold(csum_partial(buff, len, 0));
 151 }
 152
 153 #define _HAVE_ARCH_IPV6_CSUM
 154 extern __wsum
 155 __csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
 156                 __be32 proto, __wsum sum);
 157
 158 static inline __sum16
 159 csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
 160                 __u32 len, __u8 proto, __wsum sum)
 161 {
 162         return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
 163                                            htonl(proto), sum));
 164 }
 165 #endif