1 #ifndef _S390_CHECKSUM_H
2 #define _S390_CHECKSUM_H
5 * include/asm-s390/checksum.h
6 * S390 fast network checksum routines
7 * see also arch/S390/lib/checksum.c
10 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
11 * Author(s): Ulrich Hild (first version)
12 * Martin Schwidefsky (heavily optimized CKSM version)
13 * D.J. Barrow (third attempt)
16 #include <asm/uaccess.h>
19 * computes the checksum of a memory block at buff, length len,
20 * and adds in "sum" (32-bit)
22 * returns a 32-bit number suitable for feeding into itself
23 * or csum_tcpudp_magic
25 * this function must be called with even lengths, except
26 * for the last fragment, which may be odd
28 * it's best to have buff aligned on a 32-bit boundary
31 csum_partial(const unsigned char * buff, int len, unsigned int sum);
34 * csum_partial as an inline function
36 extern inline unsigned int
37 csum_partial_inline(const unsigned char * buff, int len, unsigned int sum)
39 __asm__ __volatile__ (
40 " lgr 2,%1\n" /* address in gpr 2 */
41 " lgfr 3,%2\n" /* length in gpr 3 */
42 "0: cksm %0,2\n" /* do checksum on longs */
45 : "d" (buff), "d" (len)
51 * the same as csum_partial, but copies from src while it
54 * here even more important to align src and dst on a 32-bit (or even
55 * better 64-bit) boundary
58 extern inline unsigned int
59 csum_partial_copy(const char *src, char *dst, int len,unsigned int sum)
62 return csum_partial_inline(dst, len, sum);
66 * the same as csum_partial_copy, but copies from user space.
68 * here even more important to align src and dst on a 32-bit (or even
69 * better 64-bit) boundary
71 * Copy from userspace and compute checksum. If we catch an exception
72 * then zero the rest of the buffer.
74 extern inline unsigned int
75 csum_partial_copy_from_user (const char *src, char *dst,
76 int len, unsigned int sum,
81 missing = copy_from_user(dst, src, len);
83 memset(dst + len - missing, 0, missing);
87 return csum_partial(dst, len, sum);
90 extern inline unsigned int
91 csum_partial_copy_nocheck (const char *src, char *dst, int len, unsigned int sum)
94 return csum_partial_inline(dst, len, sum);
98 * Fold a partial checksum without adding pseudo headers
100 extern inline unsigned short
101 csum_fold(unsigned int sum)
103 __asm__ __volatile__ (
104 " sr 3,3\n" /* %0 = H*65536 + L */
105 " lr 2,%0\n" /* %0 = H L, R2/R3 = H L / 0 0 */
106 " srdl 2,16\n" /* %0 = H L, R2/R3 = 0 H / L 0 */
107 " alr 2,3\n" /* %0 = H L, R2/R3 = L H / L 0 */
108 " alr %0,2\n" /* %0 = H+L+C L+H */
109 " srl %0,16\n" /* %0 = H+L+C */
110 : "+&d" (sum) : : "cc", "2", "3");
111 return ((unsigned short) ~sum);
115 * This is a version of ip_compute_csum() optimized for IP headers,
116 * which always checksum on 4 octet boundaries.
119 extern inline unsigned short
120 ip_fast_csum(unsigned char *iph, unsigned int ihl)
124 __asm__ __volatile__ (
125 " slgr %0,%0\n" /* set sum to zero */
126 " lgr 2,%1\n" /* address in gpr 2 */
127 " lgfr 3,%2\n" /* length in gpr 3 */
128 "0: cksm %0,2\n" /* do checksum on ints */
131 : "d" (iph), "d" (ihl*4)
133 return csum_fold(sum);
137 * computes the checksum of the TCP/UDP pseudo-header
138 * returns a 32-bit checksum
140 extern inline unsigned int
141 csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr,
142 unsigned short len, unsigned short proto,
145 __asm__ __volatile__ (
147 " algr %0,%1\n" /* sum += saddr */
149 " aghi %0,1\n" /* add carry */
150 "0: algr %0,%2\n" /* sum += daddr */
152 " aghi %0,1\n" /* add carry */
153 "1: algfr %0,%3\n" /* sum += (len<<16) + proto */
155 " aghi %0,1\n" /* add carry */
157 " alr %0,0\n" /* fold to 32 bits */
159 " ahi %0,1\n" /* add carry */
162 : "d" (saddr), "d" (daddr),
163 "d" (((unsigned int) len<<16) + (unsigned int) proto)
169 * computes the checksum of the TCP/UDP pseudo-header
170 * returns a 16-bit checksum, already complemented
173 extern inline unsigned short int
174 csum_tcpudp_magic(unsigned long saddr, unsigned long daddr,
175 unsigned short len, unsigned short proto,
178 return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
182 * this routine is used for miscellaneous IP-like checksums, mainly
186 extern inline unsigned short
187 ip_compute_csum(unsigned char * buff, int len)
189 return csum_fold(csum_partial_inline(buff, len, 0));
192 #endif /* _S390_CHECKSUM_H */