[Cbe-oss-dev] [RFC 1/3] powerpc: __copy_tofrom_user tweaked for Cell
Mark Nelson
markn at au1.ibm.com
Thu Jun 19 17:53:59 EST 2008
/*
* Copyright (C) 2008 Gunnar von Boehn, IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*
* __copy_tofrom_user routine optimized for CELL-BE-PPC
*
* The CELL PPC core has 1 integerunit and 1 load/store unit
* CELL: 1st level data cache = 32K - 2nd level data cache = 512K
* - 3rd level data cache = 0K
* To improve copy performance we need to prefetch source data
* far ahead to hide this latency
* For best performance instruction forms ending in "." like "andi."
* should be avoided as they are implemented in microcode on CELL.
*
* The below code is loop unrolled for the CELL cache line of 128 bytes.
*
*/
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#define PREFETCH_AHEAD 6
#define ZERO_AHEAD 4
.align 7
_GLOBAL(__copy_tofrom_user)
dcbt 0,r4 /* Prefetch ONE SRC cacheline */
std r5,-8(r1) /* remember size */
cmpldi cr1,r5,16 /* is size < 16 ? */
mr r6,r3
blt+ cr1,.Lshortcopy
.Lbigcopy:
neg r8,r3 /* LS 3 bits = # bytes to 8-byte dest bdry */
clrldi r8,r8,64-4 /* aling to 16byte boundary */
sub r7,r4,r3
cmpldi cr0,r8,0
beq+ .Ldst_aligned
.Ldst_unaligned:
mtcrf 0x01,r8 /* put #bytes to boundary into cr7 */
subf r5,r8,r5
bf cr7*4+3,1f
20: lbzx r0,r7,r6 /* copy 1 byte */
60: stb r0,0(r6)
addi r6,r6,1
1: bf cr7*4+2,2f
21: lhzx r0,r7,r6 /* copy 2 byte */
61: sth r0,0(r6)
addi r6,r6,2
2: bf cr7*4+1,4f
22: lwzx r0,r7,r6 /* copy 4 byte */
62: stw r0,0(r6)
addi r6,r6,4
4: bf cr7*4+0,8f
23: ldx r0,r7,r6 /* copy 8 byte */
63: std r0,0(r6)
addi r6,r6,8
8:
add r4,r7,r6
.Ldst_aligned:
cmpdi cr5,r5,128-1
neg r7,r6
addi r6,r6,-8 /* prepare for stdu */
addi r4,r4,-8 /* prepare for ldu */
clrldi r7,r7,64-7 /* align to cacheline boundary */
ble+ cr5,.Llessthancacheline
cmpldi cr6,r7,0
subf r5,r7,r5
srdi r7,r7,4 /* divide size by 16 */
srdi r10,r5,7 /* number of cache lines to copy */
cmpldi r10,0
li r11,0 /* number cachelines to copy with prefetch */
beq .Lnocacheprefetch
cmpldi r10,PREFETCH_AHEAD
li r12,128+8 /* prefetch distance*/
ble .Llessthanmaxprefetch
subi r11,r10,PREFETCH_AHEAD
li r10,PREFETCH_AHEAD
.Llessthanmaxprefetch:
mtctr r10
.LprefetchSRC:
dcbt r12,r4
addi r12,r12,128
bdnz .LprefetchSRC
.Lnocacheprefetch:
mtctr r7
cmpldi cr1,r5,128
clrldi r5,r5,64-7
beq cr6,.Lcachelinealigned /* */
.Laligntocacheline:
24: ld r9,0x08(r4)
25: ldu r7,0x10(r4)
64: std r9,0x08(r6)
65: stdu r7,0x10(r6)
bdnz .Laligntocacheline
.Lcachelinealigned: /* copy while cache lines */
blt- cr1,.Llessthancacheline /* size <128 */
.Louterloop:
cmpdi r11,0
mtctr r11
beq- .Lendloop
li r11,128*ZERO_AHEAD +8 /* DCBZ dist */
.align 4
/* Copy whole cachelines, optimized by prefetching SRC cacheline */
.Lloop: /* Copy aligned body */
dcbt r12,r4 /* PREFETCH SOURCE cache lines ahead*/
26: ld r9, 0x08(r4)
4000: dcbz r11,r6
27: ld r7, 0x10(r4) /* 4 register stride copy */
28: ld r8, 0x18(r4) /* 4 are optimal to hide 1st level cache lantency*/
29: ld r0, 0x20(r4)
66: std r9, 0x08(r6)
67: std r7, 0x10(r6)
68: std r8, 0x18(r6)
69: std r0, 0x20(r6)
30: ld r9, 0x28(r4)
31: ld r7, 0x30(r4)
32: ld r8, 0x38(r4)
33: ld r0, 0x40(r4)
70: std r9, 0x28(r6)
71: std r7, 0x30(r6)
72: std r8, 0x38(r6)
73: std r0, 0x40(r6)
34: ld r9, 0x48(r4)
35: ld r7, 0x50(r4)
36: ld r8, 0x58(r4)
37: ld r0, 0x60(r4)
74: std r9, 0x48(r6)
75: std r7, 0x50(r6)
76: std r8, 0x58(r6)
77: std r0, 0x60(r6)
38: ld r9, 0x68(r4)
39: ld r7, 0x70(r4)
40: ld r8, 0x78(r4)
41: ldu r0, 0x80(r4)
78: std r9, 0x68(r6)
79: std r7, 0x70(r6)
80: std r8, 0x78(r6)
81: stdu r0, 0x80(r6)
bdnz .Lloop
.Lendloop:
cmpdi r10,0
sldi r10,r10,2 /* adjust from 128 to 32 byte stride */
beq- .Lendloop2
mtctr r10
.Lloop2: /* Copy aligned body */
42: ld r9, 0x08(r4)
43: ld r7, 0x10(r4)
44: ld r8, 0x18(r4)
45: ldu r0, 0x20(r4)
82: std r9, 0x08(r6)
83: std r7, 0x10(r6)
84: std r8, 0x18(r6)
85: stdu r0, 0x20(r6)
bdnz .Lloop2
.Lendloop2:
.Llessthancacheline: /* less than cache to do ? */
cmpldi cr0,r5,16
srdi r7,r5,4 /* divide size by 16 */
blt- .Ldo_lt16
mtctr r7
.Lcopy_remaining:
46: ld r8,0x08(r4)
47: ldu r7,0x10(r4)
86: std r8,0x08(r6)
87: stdu r7,0x10(r6)
bdnz .Lcopy_remaining
.Ldo_lt16: /* less than 16 ? */
cmpldi cr0,r5,0 /* copy remaining bytes (0-15) */
beq sp1 /* no rest to copy */
addi r4,r4,8
addi r6,r6,8
.Lshortcopy: /* SIMPLE COPY to handle size =< 15 bytes */
mtcrf 0x01,r5
sub r7,r4,r6
bf- cr7*4+0,sp8
48: ldx r0,r7,r6 /* copy 8 byte */
88: std r0,0(r6)
addi r6,r6,8
sp8:
bf cr7*4+1,sp4
49: lwzx r0,r7,r6 /* copy 4 byte */
89: stw r0,0(r6)
addi r6,r6,4
sp4:
bf cr7*4+2,sp2
50: lhzx r0,r7,r6 /* copy 2 byte */
90: sth r0,0(r6)
addi r6,r6,2
sp2:
bf cr7*4+3,sp1
51: lbzx r0,r7,r6 /* copy 1 byte */
91: stb r0,0(r6)
sp1:
li r3,0
blr
/*
* exception handlers follow
* we have to return the number of bytes not copied
* for an exception on a load, we set the rest of the destination to 0
*/
151:
150:
149:
148:
add r4,r7,r6
b 1002f
123:
122:
121:
add r4,r7,r6
add r5,r8,r5 /* original size is r5 + r8, no need to go to stack */
b 1001f
120:
add r5,r8,r5 /* original size is r5 + r8, no need to go to stack */
b 1003f /* we know we can't copy any more bytes so jump to clring */
141:
140:
139:
138:
addi r6,r6,32
addi r4,r4,32
137:
136:
135:
134:
addi r6,r6,32
addi r4,r4,32
133:
132:
131:
130:
addi r6,r6,32
addi r4,r4,32
4100:
147:
146:
145:
144:
143:
142:
129:
128:
127:
126:
125:
124:
addi r6,r6,8
addi r4,r4,8
/*
* we had a fault on a load
* r6 - first unmodified byte of the destination
* r3 - original destination
* r4 - next byte we have to read for a load
*/
1002: ld r5,-8(r1)
1001: subf r3,r3,r6 /* number of bytes we did copy */
subf r5,r3,r5 /* #bytes left to go */
/*
* first see if we can copy any more bytes before hitting another exception
*/
mtctr r5
52: lbz r0,0(r4)
addi r4,r4,1
92: stb r0,0(r6)
addi r6,r6,1
bdnz 52b
li r3,0 /* huh? all copied successfully this time? */
blr
/*
* here we have trapped again, need to clear ctr bytes starting at r6
*/
152: mfctr r5
1003: li r0,0
mr r4,r6
mr r3,r5 /* return the number of bytes not copied */
1: andi. r9,r4,7
beq 3f
93: stb r0,0(r4)
addic. r5,r5,-1
addi r4,r4,1
bne 1b
blr
3: cmpldi cr1,r5,8
srdi r9,r5,3
andi. r5,r5,7
blt cr1,1000f
mtctr r9
94: std r0,0(r4)
addi r4,r4,8
bdnz 94b
1000: beqlr
mtctr r5
95: stb r0,0(r4)
addi r4,r4,1
bdnz 95b
blr
/*
* we had a fault on a store
* r6 - byte we tried to store to
* r3 - original destination
*/
181:
addi r6,r6,8
180:
addi r6,r6,8
179:
addi r6,r6,8
178:
addi r6,r6,8
177:
addi r6,r6,8
176:
addi r6,r6,8
175:
addi r6,r6,8
174:
addi r6,r6,8
173:
addi r6,r6,8
172:
addi r6,r6,8
171:
addi r6,r6,8
170:
addi r6,r6,8
185:
169:
addi r6,r6,8
184:
168:
addi r6,r6,8
187:
183:
167:
165:
addi r6,r6,8
186:
182:
166:
164:
addi r6,r6,8
191:
190:
189:
188:
163:
162:
161:
160:
ld r5,-8(r1)
subf r3,r3,r6 /* number of bytes we did copy */
subf r3,r3,r5
195:
194:
193:
blr /* #bytes not copied in r3 */
192:
mfctr r3
blr
.section __ex_table,"a"
.align 3
.llong 20b,120b
.llong 60b,160b
.llong 21b,121b
.llong 61b,161b
.llong 22b,122b
.llong 62b,162b
.llong 23b,123b
.llong 63b,163b
.llong 24b,124b
.llong 25b,125b
.llong 64b,164b
.llong 65b,165b
.llong 26b,126b
.llong 27b,127b
.llong 28b,128b
.llong 29b,129b
.llong 66b,166b
.llong 67b,167b
.llong 68b,168b
.llong 69b,169b
.llong 30b,130b
.llong 31b,131b
.llong 32b,132b
.llong 33b,133b
.llong 70b,170b
.llong 71b,171b
.llong 72b,172b
.llong 73b,173b
.llong 34b,134b
.llong 35b,135b
.llong 36b,136b
.llong 37b,137b
.llong 74b,174b
.llong 75b,175b
.llong 76b,176b
.llong 77b,177b
.llong 38b,138b
.llong 39b,139b
.llong 40b,140b
.llong 41b,141b
.llong 78b,178b
.llong 79b,179b
.llong 80b,180b
.llong 81b,181b
.llong 42b,142b
.llong 43b,143b
.llong 44b,144b
.llong 45b,145b
.llong 82b,182b
.llong 83b,183b
.llong 84b,184b
.llong 85b,185b
.llong 46b,146b
.llong 47b,147b
.llong 86b,186b
.llong 87b,187b
.llong 48b,148b
.llong 88b,188b
.llong 49b,149b
.llong 89b,189b
.llong 50b,150b
.llong 90b,190b
.llong 51b,151b
.llong 91b,191b
.llong 52b,152b
.llong 92b,192b
.llong 93b,193b
.llong 94b,194b
.llong 95b,195b
.llong 4000b,4100b
More information about the cbe-oss-dev
mailing list