1 #ifndef __UM_CHECKSUM_H 2 #define __UM_CHECKSUM_H 3 4 #include <linux/string.h> 5 #include <linux/in6.h> 6 7 /* 8 * computes the checksum of a memory block at buff, length len, 9 * and adds in "sum" (32-bit) 10 * 11 * returns a 32-bit number suitable for feeding into itself 12 * or csum_tcpudp_magic 13 * 14 * this function must be called with even lengths, except 15 * for the last fragment, which may be odd 16 * 17 * it's best to have buff aligned on a 32-bit boundary 18 */ 19 extern __wsum csum_partial(const void *buff, int len, __wsum sum); 20 21 /* 22 * Note: when you get a NULL pointer exception here this means someone 23 * passed in an incorrect kernel address to one of these functions. 24 * 25 * If you use these functions directly please don't forget the 26 * access_ok(). 27 */ 28 29 static __inline__ 30 __wsum csum_partial_copy_nocheck(const void *src, void *dst, 31 int len, __wsum sum) 32 { 33 memcpy(dst, src, len); 34 return csum_partial(dst, len, sum); 35 } 36 37 /* 38 * the same as csum_partial, but copies from src while it 39 * checksums, and handles user-space pointer exceptions correctly, when needed. 40 * 41 * here even more important to align src and dst on a 32-bit (or even 42 * better 64-bit) boundary 43 */ 44 45 static __inline__ 46 __wsum csum_partial_copy_from_user(const void __user *src, void *dst, 47 int len, __wsum sum, int *err_ptr) 48 { 49 if (copy_from_user(dst, src, len)) { 50 *err_ptr = -EFAULT; 51 return (__force __wsum)-1; 52 } 53 54 return csum_partial(dst, len, sum); 55 } 56 57 /** 58 * csum_fold - Fold and invert a 32bit checksum. 59 * sum: 32bit unfolded sum 60 * 61 * Fold a 32bit running checksum to 16bit and invert it. This is usually 62 * the last step before putting a checksum into a packet. 63 * Make sure not to mix with 64bit checksums. 64 */ 65 static inline __sum16 csum_fold(__wsum sum) 66 { 67 __asm__( 68 " addl %1,%0\n" 69 " adcl $0xffff,%0" 70 : "=r" (sum) 71 : "r" ((__force u32)sum << 16), 72 "0" ((__force u32)sum & 0xffff0000) 73 ); 74 return (__force __sum16)(~(__force u32)sum >> 16); 75 } 76 77 /** 78 * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum. 79 * @saddr: source address 80 * @daddr: destination address 81 * @len: length of packet 82 * @proto: ip protocol of packet 83 * @sum: initial sum to be added in (32bit unfolded) 84 * 85 * Returns the pseudo header checksum the input data. Result is 86 * 32bit unfolded. 87 */ 88 static inline __wsum 89 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len, 90 unsigned short proto, __wsum sum) 91 { 92 asm(" addl %1, %0\n" 93 " adcl %2, %0\n" 94 " adcl %3, %0\n" 95 " adcl $0, %0\n" 96 : "=r" (sum) 97 : "g" (daddr), "g" (saddr), "g" ((len + proto) << 8), "0" (sum)); 98 return sum; 99 } 100 101 /* 102 * computes the checksum of the TCP/UDP pseudo-header 103 * returns a 16-bit checksum, already complemented 104 */ 105 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, 106 unsigned short len, 107 unsigned short proto, 108 __wsum sum) 109 { 110 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum)); 111 } 112 113 /** 114 * ip_fast_csum - Compute the IPv4 header checksum efficiently. 115 * iph: ipv4 header 116 * ihl: length of header / 4 117 */ 118 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) 119 { 120 unsigned int sum; 121 122 asm( " movl (%1), %0\n" 123 " subl $4, %2\n" 124 " jbe 2f\n" 125 " addl 4(%1), %0\n" 126 " adcl 8(%1), %0\n" 127 " adcl 12(%1), %0\n" 128 "1: adcl 16(%1), %0\n" 129 " lea 4(%1), %1\n" 130 " decl %2\n" 131 " jne 1b\n" 132 " adcl $0, %0\n" 133 " movl %0, %2\n" 134 " shrl $16, %0\n" 135 " addw %w2, %w0\n" 136 " adcl $0, %0\n" 137 " notl %0\n" 138 "2:" 139 /* Since the input registers which are loaded with iph and ipl 140 are modified, we must also specify them as outputs, or gcc 141 will assume they contain their original values. */ 142 : "=r" (sum), "=r" (iph), "=r" (ihl) 143 : "1" (iph), "2" (ihl) 144 : "memory"); 145 return (__force __sum16)sum; 146 } 147 148 #ifdef CONFIG_X86_32 149 # include "checksum_32.h" 150 #else 151 # include "checksum_64.h" 152 #endif 153 154 #endif 155