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Linux/arch/arm/include/asm/checksum.h

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

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