1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * User Space Access Routines
4 *
5 * Copyright (C) 2000-2002 Hewlett-Packard (John Marvin)
6 * Copyright (C) 2000 Richard Hirst <rhirst with parisc-linux.org>
7 * Copyright (C) 2001 Matthieu Delahaye <delahaym at esiee.fr>
8 * Copyright (C) 2003 Randolph Chung <tausq with parisc-linux.org>
9 * Copyright (C) 2017 Helge Deller <deller@gmx.de>
10 * Copyright (C) 2017 John David Anglin <dave.anglin@bell.net>
11 */
12
13/*
14 * These routines still have plenty of room for optimization
15 * (word & doubleword load/store, dual issue, store hints, etc.).
16 */
17
18/*
19 * The following routines assume that space register 3 (sr3) contains
20 * the space id associated with the current users address space.
21 */
22
23
24 .text
25
26#include <asm/assembly.h>
27#include <asm/errno.h>
28#include <linux/linkage.h>
29
30 /*
31 * unsigned long lclear_user(void *to, unsigned long n)
32 *
33 * Returns 0 for success.
34 * otherwise, returns number of bytes not transferred.
35 */
36
37ENTRY_CFI(lclear_user)
38 comib,=,n 0,%r25,$lclu_done
39$lclu_loop:
40 addib,<> -1,%r25,$lclu_loop
411: stbs,ma %r0,1(%sr3,%r26)
42
43$lclu_done:
44 bv %r0(%r2)
45 copy %r25,%r28
46
472: b $lclu_done
48 ldo 1(%r25),%r25
49
50 ASM_EXCEPTIONTABLE_ENTRY(1b,2b)
51ENDPROC_CFI(lclear_user)
52
53
54/*
55 * unsigned long pa_memcpy(void *dstp, const void *srcp, unsigned long len)
56 *
57 * Inputs:
58 * - sr1 already contains space of source region
59 * - sr2 already contains space of destination region
60 *
61 * Returns:
62 * - number of bytes that could not be copied.
63 * On success, this will be zero.
64 *
65 * This code is based on a C-implementation of a copy routine written by
66 * Randolph Chung, which in turn was derived from the glibc.
67 *
68 * Several strategies are tried to try to get the best performance for various
69 * conditions. In the optimal case, we copy by loops that copy 32- or 16-bytes
70 * at a time using general registers. Unaligned copies are handled either by
71 * aligning the destination and then using shift-and-write method, or in a few
72 * cases by falling back to a byte-at-a-time copy.
73 *
74 * Testing with various alignments and buffer sizes shows that this code is
75 * often >10x faster than a simple byte-at-a-time copy, even for strangely
76 * aligned operands. It is interesting to note that the glibc version of memcpy
77 * (written in C) is actually quite fast already. This routine is able to beat
78 * it by 30-40% for aligned copies because of the loop unrolling, but in some
79 * cases the glibc version is still slightly faster. This lends more
80 * credibility that gcc can generate very good code as long as we are careful.
81 *
82 * Possible optimizations:
83 * - add cache prefetching
84 * - try not to use the post-increment address modifiers; they may create
85 * additional interlocks. Assumption is that those were only efficient on old
86 * machines (pre PA8000 processors)
87 */
88
89 dst = arg0
90 src = arg1
91 len = arg2
92 end = arg3
93 t1 = r19
94 t2 = r20
95 t3 = r21
96 t4 = r22
97 srcspc = sr1
98 dstspc = sr2
99
100 t0 = r1
101 a1 = t1
102 a2 = t2
103 a3 = t3
104 a0 = t4
105
106 save_src = ret0
107 save_dst = ret1
108 save_len = r31
109
110ENTRY_CFI(pa_memcpy)
111 /* Last destination address */
112 add dst,len,end
113
114 /* short copy with less than 16 bytes? */
115 cmpib,COND(>>=),n 15,len,.Lbyte_loop
116
117 /* same alignment? */
118 xor src,dst,t0
119 extru t0,31,2,t1
120 cmpib,<>,n 0,t1,.Lunaligned_copy
121
122#ifdef CONFIG_64BIT
123 /* only do 64-bit copies if we can get aligned. */
124 extru t0,31,3,t1
125 cmpib,<>,n 0,t1,.Lalign_loop32
126
127 /* loop until we are 64-bit aligned */
128.Lalign_loop64:
129 extru dst,31,3,t1
130 cmpib,=,n 0,t1,.Lcopy_loop_16_start
13120: ldb,ma 1(srcspc,src),t1
13221: stb,ma t1,1(dstspc,dst)
133 b .Lalign_loop64
134 ldo -1(len),len
135
136 ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
137 ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
138
139.Lcopy_loop_16_start:
140 ldi 31,t0
141.Lcopy_loop_16:
142 cmpb,COND(>>=),n t0,len,.Lword_loop
143
14410: ldd 0(srcspc,src),t1
14511: ldd 8(srcspc,src),t2
146 ldo 16(src),src
14712: std,ma t1,8(dstspc,dst)
14813: std,ma t2,8(dstspc,dst)
14914: ldd 0(srcspc,src),t1
15015: ldd 8(srcspc,src),t2
151 ldo 16(src),src
15216: std,ma t1,8(dstspc,dst)
15317: std,ma t2,8(dstspc,dst)
154
155 ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
156 ASM_EXCEPTIONTABLE_ENTRY(11b,.Lcopy16_fault)
157 ASM_EXCEPTIONTABLE_ENTRY(12b,.Lcopy_done)
158 ASM_EXCEPTIONTABLE_ENTRY(13b,.Lcopy_done)
159 ASM_EXCEPTIONTABLE_ENTRY(14b,.Lcopy_done)
160 ASM_EXCEPTIONTABLE_ENTRY(15b,.Lcopy16_fault)
161 ASM_EXCEPTIONTABLE_ENTRY(16b,.Lcopy_done)
162 ASM_EXCEPTIONTABLE_ENTRY(17b,.Lcopy_done)
163
164 b .Lcopy_loop_16
165 ldo -32(len),len
166
167.Lword_loop:
168 cmpib,COND(>>=),n 3,len,.Lbyte_loop
16920: ldw,ma 4(srcspc,src),t1
17021: stw,ma t1,4(dstspc,dst)
171 b .Lword_loop
172 ldo -4(len),len
173
174 ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
175 ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
176
177#endif /* CONFIG_64BIT */
178
179 /* loop until we are 32-bit aligned */
180.Lalign_loop32:
181 extru dst,31,2,t1
182 cmpib,=,n 0,t1,.Lcopy_loop_8
18320: ldb,ma 1(srcspc,src),t1
18421: stb,ma t1,1(dstspc,dst)
185 b .Lalign_loop32
186 ldo -1(len),len
187
188 ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
189 ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
190
191
192.Lcopy_loop_8:
193 cmpib,COND(>>=),n 15,len,.Lbyte_loop
194
19510: ldw 0(srcspc,src),t1
19611: ldw 4(srcspc,src),t2
19712: stw,ma t1,4(dstspc,dst)
19813: stw,ma t2,4(dstspc,dst)
19914: ldw 8(srcspc,src),t1
20015: ldw 12(srcspc,src),t2
201 ldo 16(src),src
20216: stw,ma t1,4(dstspc,dst)
20317: stw,ma t2,4(dstspc,dst)
204
205 ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
206 ASM_EXCEPTIONTABLE_ENTRY(11b,.Lcopy8_fault)
207 ASM_EXCEPTIONTABLE_ENTRY(12b,.Lcopy_done)
208 ASM_EXCEPTIONTABLE_ENTRY(13b,.Lcopy_done)
209 ASM_EXCEPTIONTABLE_ENTRY(14b,.Lcopy_done)
210 ASM_EXCEPTIONTABLE_ENTRY(15b,.Lcopy8_fault)
211 ASM_EXCEPTIONTABLE_ENTRY(16b,.Lcopy_done)
212 ASM_EXCEPTIONTABLE_ENTRY(17b,.Lcopy_done)
213
214 b .Lcopy_loop_8
215 ldo -16(len),len
216
217.Lbyte_loop:
218 cmpclr,COND(<>) len,%r0,%r0
219 b,n .Lcopy_done
22020: ldb 0(srcspc,src),t1
221 ldo 1(src),src
22221: stb,ma t1,1(dstspc,dst)
223 b .Lbyte_loop
224 ldo -1(len),len
225
226 ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
227 ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
228
229.Lcopy_done:
230 bv %r0(%r2)
231 sub end,dst,ret0
232
233
234 /* src and dst are not aligned the same way. */
235 /* need to go the hard way */
236.Lunaligned_copy:
237 /* align until dst is 32bit-word-aligned */
238 extru dst,31,2,t1
239 cmpib,=,n 0,t1,.Lcopy_dstaligned
24020: ldb 0(srcspc,src),t1
241 ldo 1(src),src
24221: stb,ma t1,1(dstspc,dst)
243 b .Lunaligned_copy
244 ldo -1(len),len
245
246 ASM_EXCEPTIONTABLE_ENTRY(20b,.Lcopy_done)
247 ASM_EXCEPTIONTABLE_ENTRY(21b,.Lcopy_done)
248
249.Lcopy_dstaligned:
250
251 /* store src, dst and len in safe place */
252 copy src,save_src
253 copy dst,save_dst
254 copy len,save_len
255
256 /* len now needs give number of words to copy */
257 SHRREG len,2,len
258
259 /*
260 * Copy from a not-aligned src to an aligned dst using shifts.
261 * Handles 4 words per loop.
262 */
263
264 depw,z src,28,2,t0
265 subi 32,t0,t0
266 mtsar t0
267 extru len,31,2,t0
268 cmpib,= 2,t0,.Lcase2
269 /* Make src aligned by rounding it down. */
270 depi 0,31,2,src
271
272 cmpiclr,<> 3,t0,%r0
273 b,n .Lcase3
274 cmpiclr,<> 1,t0,%r0
275 b,n .Lcase1
276.Lcase0:
277 cmpb,COND(=) %r0,len,.Lcda_finish
278 nop
279
2801: ldw,ma 4(srcspc,src), a3
281 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
2821: ldw,ma 4(srcspc,src), a0
283 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
284 b,n .Ldo3
285.Lcase1:
2861: ldw,ma 4(srcspc,src), a2
287 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
2881: ldw,ma 4(srcspc,src), a3
289 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
290 ldo -1(len),len
291 cmpb,COND(=),n %r0,len,.Ldo0
292.Ldo4:
2931: ldw,ma 4(srcspc,src), a0
294 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
295 shrpw a2, a3, %sar, t0
2961: stw,ma t0, 4(dstspc,dst)
297 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
298.Ldo3:
2991: ldw,ma 4(srcspc,src), a1
300 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
301 shrpw a3, a0, %sar, t0
3021: stw,ma t0, 4(dstspc,dst)
303 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
304.Ldo2:
3051: ldw,ma 4(srcspc,src), a2
306 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
307 shrpw a0, a1, %sar, t0
3081: stw,ma t0, 4(dstspc,dst)
309 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
310.Ldo1:
3111: ldw,ma 4(srcspc,src), a3
312 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
313 shrpw a1, a2, %sar, t0
3141: stw,ma t0, 4(dstspc,dst)
315 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
316 ldo -4(len),len
317 cmpb,COND(<>) %r0,len,.Ldo4
318 nop
319.Ldo0:
320 shrpw a2, a3, %sar, t0
3211: stw,ma t0, 4(dstspc,dst)
322 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcopy_done)
323
324.Lcda_rdfault:
325.Lcda_finish:
326 /* calculate new src, dst and len and jump to byte-copy loop */
327 sub dst,save_dst,t0
328 add save_src,t0,src
329 b .Lbyte_loop
330 sub save_len,t0,len
331
332.Lcase3:
3331: ldw,ma 4(srcspc,src), a0
334 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
3351: ldw,ma 4(srcspc,src), a1
336 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
337 b .Ldo2
338 ldo 1(len),len
339.Lcase2:
3401: ldw,ma 4(srcspc,src), a1
341 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
3421: ldw,ma 4(srcspc,src), a2
343 ASM_EXCEPTIONTABLE_ENTRY(1b,.Lcda_rdfault)
344 b .Ldo1
345 ldo 2(len),len
346
347
348 /* fault exception fixup handlers: */
349#ifdef CONFIG_64BIT
350.Lcopy16_fault:
351 b .Lcopy_done
35210: std,ma t1,8(dstspc,dst)
353 ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
354#endif
355
356.Lcopy8_fault:
357 b .Lcopy_done
35810: stw,ma t1,4(dstspc,dst)
359 ASM_EXCEPTIONTABLE_ENTRY(10b,.Lcopy_done)
360ENDPROC_CFI(pa_memcpy)
361
362 .end
363

source code of linux/arch/parisc/lib/lusercopy.S