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