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, __wsum sum); 39 40 __wsum 41 csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr); 42 43 /* 44 * Fold a partial checksum without adding pseudo headers 45 */ 46 static inline __sum16 csum_fold(__wsum sum) 47 { 48 __asm__( 49 "add %0, %1, %1, ror #16 @ csum_fold" 50 : "=r" (sum) 51 : "r" (sum) 52 : "cc"); 53 return (__force __sum16)(~(__force u32)sum >> 16); 54 } 55 56 /* 57 * This is a version of ip_compute_csum() optimized for IP headers, 58 * which always checksum on 4 octet boundaries. 59 */ 60 static inline __sum16 61 ip_fast_csum(const void *iph, unsigned int ihl) 62 { 63 unsigned int tmp1; 64 __wsum sum; 65 66 __asm__ __volatile__( 67 "ldr %0, [%1], #4 @ ip_fast_csum \n\ 68 ldr %3, [%1], #4 \n\ 69 sub %2, %2, #5 \n\ 70 adds %0, %0, %3 \n\ 71 ldr %3, [%1], #4 \n\ 72 adcs %0, %0, %3 \n\ 73 ldr %3, [%1], #4 \n\ 74 1: adcs %0, %0, %3 \n\ 75 ldr %3, [%1], #4 \n\ 76 tst %2, #15 @ do this carefully \n\ 77 subne %2, %2, #1 @ without destroying \n\ 78 bne 1b @ the carry flag \n\ 79 adcs %0, %0, %3 \n\ 80 adc %0, %0, #0" 81 : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1) 82 : "1" (iph), "2" (ihl) 83 : "cc", "memory"); 84 return csum_fold(sum); 85 } 86 87 static inline __wsum 88 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, 89 __u8 proto, __wsum sum) 90 { 91 u32 lenprot = len + proto; 92 if (__builtin_constant_p(sum) && sum == 0) { 93 __asm__( 94 "adds %0, %1, %2 @ csum_tcpudp_nofold0 \n\t" 95 #ifdef __ARMEB__ 96 "adcs %0, %0, %3 \n\t" 97 #else 98 "adcs %0, %0, %3, ror #8 \n\t" 99 #endif 100 "adc %0, %0, #0" 101 : "=&r" (sum) 102 : "r" (daddr), "r" (saddr), "r" (lenprot) 103 : "cc"); 104 } else { 105 __asm__( 106 "adds %0, %1, %2 @ csum_tcpudp_nofold \n\t" 107 "adcs %0, %0, %3 \n\t" 108 #ifdef __ARMEB__ 109 "adcs %0, %0, %4 \n\t" 110 #else 111 "adcs %0, %0, %4, ror #8 \n\t" 112 #endif 113 "adc %0, %0, #0" 114 : "=&r"(sum) 115 : "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot) 116 : "cc"); 117 } 118 return sum; 119 } 120 /* 121 * computes the checksum of the TCP/UDP pseudo-header 122 * returns a 16-bit checksum, already complemented 123 */ 124 static inline __sum16 125 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, 126 __u8 proto, __wsum sum) 127 { 128 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum)); 129 } 130 131 132 /* 133 * this routine is used for miscellaneous IP-like checksums, mainly 134 * in icmp.c 135 */ 136 static inline __sum16 137 ip_compute_csum(const void *buff, int len) 138 { 139 return csum_fold(csum_partial(buff, len, 0)); 140 } 141 142 #define _HAVE_ARCH_IPV6_CSUM 143 extern __wsum 144 __csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len, 145 __be32 proto, __wsum sum); 146 147 static inline __sum16 148 csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, 149 __u32 len, __u8 proto, __wsum sum) 150 { 151 return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len), 152 htonl(proto), sum)); 153 } 154 #endif 155