1/*
2 * This file contains assembly-language implementations
3 * of IP-style 1's complement checksum routines.
4 *
5 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
6 *
7 *  This program is free software; you can redistribute it and/or
8 *  modify it under the terms of the GNU General Public License
9 *  as published by the Free Software Foundation; either version
10 *  2 of the License, or (at your option) any later version.
11 *
12 * Severely hacked about by Paul Mackerras (paulus@cs.anu.edu.au).
13 */
14
15#include <linux/sys.h>
16#include <asm/processor.h>
17#include <asm/errno.h>
18#include <asm/ppc_asm.h>
19
20/*
21 * ip_fast_csum(r3=buf, r4=len) -- Optimized for IP header
22 * len is in words and is always >= 5.
23 *
24 * In practice len == 5, but this is not guaranteed.  So this code does not
25 * attempt to use doubleword instructions.
26 */
27_GLOBAL(ip_fast_csum)
28	lwz	r0,0(r3)
29	lwzu	r5,4(r3)
30	addic.	r4,r4,-2
31	addc	r0,r0,r5
32	mtctr	r4
33	blelr-
341:	lwzu	r4,4(r3)
35	adde	r0,r0,r4
36	bdnz	1b
37	addze	r0,r0		/* add in final carry */
38        rldicl  r4,r0,32,0      /* fold two 32-bit halves together */
39        add     r0,r0,r4
40        srdi    r0,r0,32
41	rlwinm	r3,r0,16,0,31	/* fold two halves together */
42	add	r3,r0,r3
43	not	r3,r3
44	srwi	r3,r3,16
45	blr
46
47/*
48 * Compute checksum of TCP or UDP pseudo-header:
49 *   csum_tcpudp_magic(r3=saddr, r4=daddr, r5=len, r6=proto, r7=sum)
50 * No real gain trying to do this specially for 64 bit, but
51 * the 32 bit addition may spill into the upper bits of
52 * the doubleword so we still must fold it down from 64.
53 */
54_GLOBAL(csum_tcpudp_magic)
55	rlwimi	r5,r6,16,0,15	/* put proto in upper half of len */
56	addc	r0,r3,r4	/* add 4 32-bit words together */
57	adde	r0,r0,r5
58	adde	r0,r0,r7
59        rldicl  r4,r0,32,0      /* fold 64 bit value */
60        add     r0,r4,r0
61        srdi    r0,r0,32
62	rlwinm	r3,r0,16,0,31	/* fold two halves together */
63	add	r3,r0,r3
64	not	r3,r3
65	srwi	r3,r3,16
66	blr
67
68/*
69 * Computes the checksum of a memory block at buff, length len,
70 * and adds in "sum" (32-bit).
71 *
72 * This code assumes at least halfword alignment, though the length
73 * can be any number of bytes.  The sum is accumulated in r5.
74 *
75 * csum_partial(r3=buff, r4=len, r5=sum)
76 */
77_GLOBAL(csum_partial)
78        subi	r3,r3,8		/* we'll offset by 8 for the loads */
79        srdi.	r6,r4,3         /* divide by 8 for doubleword count */
80        addic   r5,r5,0         /* clear carry */
81        beq	3f              /* if we're doing < 8 bytes */
82        andi.	r0,r3,2         /* aligned on a word boundary already? */
83        beq+	1f
84        lhz     r6,8(r3)        /* do 2 bytes to get aligned */
85        addi    r3,r3,2
86        subi    r4,r4,2
87        addc    r5,r5,r6
88        srdi.   r6,r4,3         /* recompute number of doublewords */
89        beq     3f              /* any left? */
901:      mtctr   r6
912:      ldu     r6,8(r3)        /* main sum loop */
92        adde    r5,r5,r6
93        bdnz    2b
94        andi.	r4,r4,7         /* compute bytes left to sum after doublewords */
953:	cmpwi	0,r4,4		/* is at least a full word left? */
96	blt	4f
97	lwz	r6,8(r3)	/* sum this word */
98	addi	r3,r3,4
99	subi	r4,r4,4
100	adde	r5,r5,r6
1014:	cmpwi	0,r4,2		/* is at least a halfword left? */
102        blt+	5f
103        lhz     r6,8(r3)        /* sum this halfword */
104        addi    r3,r3,2
105        subi    r4,r4,2
106        adde    r5,r5,r6
1075:	cmpwi	0,r4,1		/* is at least a byte left? */
108        bne+    6f
109        lbz     r6,8(r3)        /* sum this byte */
110        slwi    r6,r6,8         /* this byte is assumed to be the upper byte of a halfword */
111        adde    r5,r5,r6
1126:      addze	r5,r5		/* add in final carry */
113	rldicl  r4,r5,32,0      /* fold two 32-bit halves together */
114        add     r3,r4,r5
115        srdi    r3,r3,32
116        blr
117
118/*
119 * Computes the checksum of a memory block at src, length len,
120 * and adds in "sum" (32-bit), while copying the block to dst.
121 * If an access exception occurs on src or dst, it stores -EFAULT
122 * to *src_err or *dst_err respectively, and (for an error on
123 * src) zeroes the rest of dst.
124 *
125 * This code needs to be reworked to take advantage of 64 bit sum+copy.
126 * However, due to tokenring halfword alignment problems this will be very
127 * tricky.  For now we'll leave it until we instrument it somehow.
128 *
129 * csum_partial_copy_generic(r3=src, r4=dst, r5=len, r6=sum, r7=src_err, r8=dst_err)
130 */
131_GLOBAL(csum_partial_copy_generic)
132	addic	r0,r6,0
133	subi	r3,r3,4
134	subi	r4,r4,4
135	srwi.	r6,r5,2
136	beq	3f		/* if we're doing < 4 bytes */
137	andi.	r9,r4,2		/* Align dst to longword boundary */
138	beq+	1f
13981:	lhz	r6,4(r3)	/* do 2 bytes to get aligned */
140	addi	r3,r3,2
141	subi	r5,r5,2
14291:	sth	r6,4(r4)
143	addi	r4,r4,2
144	addc	r0,r0,r6
145	srwi.	r6,r5,2		/* # words to do */
146	beq	3f
1471:	mtctr	r6
14882:	lwzu	r6,4(r3)	/* the bdnz has zero overhead, so it should */
14992:	stwu	r6,4(r4)	/* be unnecessary to unroll this loop */
150	adde	r0,r0,r6
151	bdnz	82b
152	andi.	r5,r5,3
1533:	cmpwi	0,r5,2
154	blt+	4f
15583:	lhz	r6,4(r3)
156	addi	r3,r3,2
157	subi	r5,r5,2
15893:	sth	r6,4(r4)
159	addi	r4,r4,2
160	adde	r0,r0,r6
1614:	cmpwi	0,r5,1
162	bne+	5f
16384:	lbz	r6,4(r3)
16494:	stb	r6,4(r4)
165	slwi	r6,r6,8		/* Upper byte of word */
166	adde	r0,r0,r6
1675:	addze	r3,r0		/* add in final carry (unlikely with 64-bit regs) */
168        rldicl  r4,r3,32,0      /* fold 64 bit value */
169        add     r3,r4,r3
170        srdi    r3,r3,32
171	blr
172
173/* These shouldn't go in the fixup section, since that would
174   cause the ex_table addresses to get out of order. */
175
176	.globl src_error_1
177src_error_1:
178	li	r6,0
179	subi	r5,r5,2
18095:	sth	r6,4(r4)
181	addi	r4,r4,2
182	srwi.	r6,r5,2
183	beq	3f
184	mtctr	r6
185	.globl src_error_2
186src_error_2:
187	li	r6,0
18896:	stwu	r6,4(r4)
189	bdnz	96b
1903:	andi.	r5,r5,3
191	beq	src_error
192	.globl src_error_3
193src_error_3:
194	li	r6,0
195	mtctr	r5
196	addi	r4,r4,3
19797:	stbu	r6,1(r4)
198	bdnz	97b
199	.globl src_error
200src_error:
201	cmpdi	0,r7,0
202	beq	1f
203	li	r6,-EFAULT
204	stw	r6,0(r7)
2051:	addze	r3,r0
206	blr
207
208	.globl dst_error
209dst_error:
210	cmpdi	0,r8,0
211	beq	1f
212	li	r6,-EFAULT
213	stw	r6,0(r8)
2141:	addze	r3,r0
215	blr
216
217.section __ex_table,"a"
218	.align  3
219	.llong	81b,src_error_1
220	.llong	91b,dst_error
221	.llong	82b,src_error_2
222	.llong	92b,dst_error
223	.llong	83b,src_error_3
224	.llong	93b,dst_error
225	.llong	84b,src_error_3
226	.llong	94b,dst_error
227	.llong	95b,dst_error
228	.llong	96b,dst_error
229	.llong	97b,dst_error
230