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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * IP/TCP/UDP checksumming routines
7 *
8 * Authors: Jorge Cwik, <jorge@laser.satlink.net>
9 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
10 * Tom May, <ftom@netcom.com>
11 * Pentium Pro/II routines:
12 * Alexander Kjeldaas <astor@guardian.no>
13 * Finn Arne Gangstad <finnag@guardian.no>
14 * Lots of code moved from tcp.c and ip.c; see those files
15 * for more names.
16 *
17 * Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
18 * handling.
19 * Andi Kleen, add zeroing on error
20 * converted to pure assembler
21 *
22 * This program is free software; you can redistribute it and/or
23 * modify it under the terms of the GNU General Public License
24 * as published by the Free Software Foundation; either version
25 * 2 of the License, or (at your option) any later version.
26 */
27
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <asm/errno.h>
H. Peter Anvinf542c5d2012-04-20 12:19:52 -070029#include <asm/asm.h>
Al Viro784d5692016-01-11 11:04:34 -050030#include <asm/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32/*
33 * computes a partial checksum, e.g. for TCP/UDP fragments
34 */
35
36/*
37unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
38 */
39
40.text
41.align 4
Bodo Stroesser7d37c6d2005-05-05 16:15:36 -070042.globl csum_partial
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
45
46 /*
47 * Experiments with Ethernet and SLIP connections show that buff
48 * is aligned on either a 2-byte or 4-byte boundary. We get at
49 * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
50 * Fortunately, it is easy to convert 2-byte alignment to 4-byte
51 * alignment for the unrolled loop.
52 */
Bodo Stroesser7d37c6d2005-05-05 16:15:36 -070053csum_partial:
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 pushl %esi
55 pushl %ebx
56 movl 20(%esp),%eax # Function arg: unsigned int sum
57 movl 16(%esp),%ecx # Function arg: int len
58 movl 12(%esp),%esi # Function arg: unsigned char *buff
59 testl $2, %esi # Check alignment.
60 jz 2f # Jump if alignment is ok.
61 subl $2, %ecx # Alignment uses up two bytes.
62 jae 1f # Jump if we had at least two bytes.
63 addl $2, %ecx # ecx was < 2. Deal with it.
64 jmp 4f
651: movw (%esi), %bx
66 addl $2, %esi
67 addw %bx, %ax
68 adcl $0, %eax
692:
70 movl %ecx, %edx
71 shrl $5, %ecx
72 jz 2f
73 testl %esi, %esi
741: movl (%esi), %ebx
75 adcl %ebx, %eax
76 movl 4(%esi), %ebx
77 adcl %ebx, %eax
78 movl 8(%esi), %ebx
79 adcl %ebx, %eax
80 movl 12(%esi), %ebx
81 adcl %ebx, %eax
82 movl 16(%esi), %ebx
83 adcl %ebx, %eax
84 movl 20(%esi), %ebx
85 adcl %ebx, %eax
86 movl 24(%esi), %ebx
87 adcl %ebx, %eax
88 movl 28(%esi), %ebx
89 adcl %ebx, %eax
90 lea 32(%esi), %esi
91 dec %ecx
92 jne 1b
93 adcl $0, %eax
942: movl %edx, %ecx
95 andl $0x1c, %edx
96 je 4f
97 shrl $2, %edx # This clears CF
983: adcl (%esi), %eax
99 lea 4(%esi), %esi
100 dec %edx
101 jne 3b
102 adcl $0, %eax
1034: andl $3, %ecx
104 jz 7f
105 cmpl $2, %ecx
106 jb 5f
107 movw (%esi),%cx
108 leal 2(%esi),%esi
109 je 6f
110 shll $16,%ecx
1115: movb (%esi),%cl
1126: addl %ecx,%eax
113 adcl $0, %eax
1147:
115 popl %ebx
116 popl %esi
117 ret
118
119#else
120
121/* Version for PentiumII/PPro */
122
Bodo Stroesser7d37c6d2005-05-05 16:15:36 -0700123csum_partial:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 pushl %esi
125 pushl %ebx
126 movl 20(%esp),%eax # Function arg: unsigned int sum
127 movl 16(%esp),%ecx # Function arg: int len
128 movl 12(%esp),%esi # Function arg: const unsigned char *buf
129
130 testl $2, %esi
131 jnz 30f
13210:
133 movl %ecx, %edx
134 movl %ecx, %ebx
135 andl $0x7c, %ebx
136 shrl $7, %ecx
137 addl %ebx,%esi
138 shrl $2, %ebx
139 negl %ebx
140 lea 45f(%ebx,%ebx,2), %ebx
141 testl %esi, %esi
142 jmp *%ebx
143
144 # Handle 2-byte-aligned regions
14520: addw (%esi), %ax
146 lea 2(%esi), %esi
147 adcl $0, %eax
148 jmp 10b
149
15030: subl $2, %ecx
151 ja 20b
152 je 32f
153 movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
154 addl %ebx, %eax
155 adcl $0, %eax
156 jmp 80f
15732:
158 addw (%esi), %ax # csumming 2 bytes, 2-aligned
159 adcl $0, %eax
160 jmp 80f
161
16240:
163 addl -128(%esi), %eax
164 adcl -124(%esi), %eax
165 adcl -120(%esi), %eax
166 adcl -116(%esi), %eax
167 adcl -112(%esi), %eax
168 adcl -108(%esi), %eax
169 adcl -104(%esi), %eax
170 adcl -100(%esi), %eax
171 adcl -96(%esi), %eax
172 adcl -92(%esi), %eax
173 adcl -88(%esi), %eax
174 adcl -84(%esi), %eax
175 adcl -80(%esi), %eax
176 adcl -76(%esi), %eax
177 adcl -72(%esi), %eax
178 adcl -68(%esi), %eax
179 adcl -64(%esi), %eax
180 adcl -60(%esi), %eax
181 adcl -56(%esi), %eax
182 adcl -52(%esi), %eax
183 adcl -48(%esi), %eax
184 adcl -44(%esi), %eax
185 adcl -40(%esi), %eax
186 adcl -36(%esi), %eax
187 adcl -32(%esi), %eax
188 adcl -28(%esi), %eax
189 adcl -24(%esi), %eax
190 adcl -20(%esi), %eax
191 adcl -16(%esi), %eax
192 adcl -12(%esi), %eax
193 adcl -8(%esi), %eax
194 adcl -4(%esi), %eax
19545:
196 lea 128(%esi), %esi
197 adcl $0, %eax
198 dec %ecx
199 jge 40b
200 movl %edx, %ecx
20150: andl $3, %ecx
202 jz 80f
203
204 # Handle the last 1-3 bytes without jumping
205 notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
206 movl $0xffffff,%ebx # by the shll and shrl instructions
207 shll $3,%ecx
208 shrl %cl,%ebx
209 andl -128(%esi),%ebx # esi is 4-aligned so should be ok
210 addl %ebx,%eax
211 adcl $0,%eax
21280:
213 popl %ebx
214 popl %esi
215 ret
216
217#endif
Al Viro784d5692016-01-11 11:04:34 -0500218 EXPORT_SYMBOL(csum_partial)