aboutsummaryrefslogtreecommitdiffstats
path: root/arch/parisc/lib/memcpy.c
blob: 2c43ebe99a9ce6492f53026f3530a07ebc657df1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
/*
 *    Optimized memory copy routines.
 *
 *    Copyright (C) 2004 Randolph Chung <tausq@debian.org>
 *
 *    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, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *    Portions derived from the GNU C Library
 *    Copyright (C) 1991, 1997, 2003 Free Software Foundation, Inc.
 *
 * Several strategies are tried to try to get the best performance for various
 * conditions. In the optimal case, we copy 64-bytes in an unrolled loop using 
 * fp regs. This is followed by loops that copy 32- or 16-bytes at a time using
 * general registers.  Unaligned copies are handled either by aligning the 
 * destination and then using shift-and-write method, or in a few cases by 
 * falling back to a byte-at-a-time copy.
 *
 * I chose to implement this in C because it is easier to maintain and debug,
 * and in my experiments it appears that the C code generated by gcc (3.3/3.4
 * at the time of writing) is fairly optimal. Unfortunately some of the 
 * semantics of the copy routine (exception handling) is difficult to express
 * in C, so we have to play some tricks to get it to work.
 *
 * All the loads and stores are done via explicit asm() code in order to use
 * the right space registers. 
 * 
 * Testing with various alignments and buffer sizes shows that this code is 
 * often >10x faster than a simple byte-at-a-time copy, even for strangely
 * aligned operands. It is interesting to note that the glibc version
 * of memcpy (written in C) is actually quite fast already. This routine is 
 * able to beat it by 30-40% for aligned copies because of the loop unrolling, 
 * but in some cases the glibc version is still slightly faster. This lends 
 * more credibility that gcc can generate very good code as long as we are 
 * careful.
 *
 * TODO:
 * - cache prefetching needs more experimentation to get optimal settings
 * - try not to use the post-increment address modifiers; they create additional
 *   interlocks
 * - replace byte-copy loops with stybs sequences
 */

#ifdef __KERNEL__
#include <linux/module.h>
#include <linux/compiler.h>
#include <asm/uaccess.h>
#define s_space "%%sr1"
#define d_space "%%sr2"
#else
#include "memcpy.h"
#define s_space "%%sr0"
#define d_space "%%sr0"
#define pa_memcpy new2_copy
#endif

DECLARE_PER_CPU(struct exception_data, exception_data);

#define preserve_branch(label)	do {					\
	volatile int dummy;						\
	/* The following branch is never taken, it's just here to  */	\
	/* prevent gcc from optimizing away our exception code. */ 	\
	if (unlikely(dummy != dummy))					\
		goto label;						\
} while (0)

#define get_user_space() (segment_eq(get_fs(), KERNEL_DS) ? 0 : mfsp(3))
#define get_kernel_space() (0)

#define MERGE(w0, sh_1, w1, sh_2)  ({					\
	unsigned int _r;						\
	asm volatile (							\
	"mtsar %3\n"							\
	"shrpw %1, %2, %%sar, %0\n"					\
	: "=r"(_r)							\
	: "r"(w0), "r"(w1), "r"(sh_2)					\
	);								\
	_r;								\
})
#define THRESHOLD	16

#ifdef DEBUG_MEMCPY
#define DPRINTF(fmt, args...) do { printk(KERN_DEBUG "%s:%d:%s ", __FILE__, __LINE__, __FUNCTION__ ); printk(KERN_DEBUG fmt, ##args ); } while (0)
#else
#define DPRINTF(fmt, args...)
#endif

#define def_load_ai_insn(_insn,_sz,_tt,_s,_a,_t,_e)	\
	__asm__ __volatile__ (				\
	"1:\t" #_insn ",ma " #_sz "(" _s ",%1), %0\n\t"	\
	ASM_EXCEPTIONTABLE_ENTRY(1b,_e)			\
	: _tt(_t), "+r"(_a)				\
	: 						\
	: "r8")

#define def_store_ai_insn(_insn,_sz,_tt,_s,_a,_t,_e) 	\
	__asm__ __volatile__ (				\
	"1:\t" #_insn ",ma %1, " #_sz "(" _s ",%0)\n\t"	\
	ASM_EXCEPTIONTABLE_ENTRY(1b,_e)			\
	: "+r"(_a) 					\
	: _tt(_t)					\
	: "r8")

#define ldbma(_s, _a, _t, _e) def_load_ai_insn(ldbs,1,"=r",_s,_a,_t,_e)
#define stbma(_s, _t, _a, _e) def_store_ai_insn(stbs,1,"r",_s,_a,_t,_e)
#define ldwma(_s, _a, _t, _e) def_load_ai_insn(ldw,4,"=r",_s,_a,_t,_e)
#define stwma(_s, _t, _a, _e) def_store_ai_insn(stw,4,"r",_s,_a,_t,_e)
#define flddma(_s, _a, _t, _e) def_load_ai_insn(fldd,8,"=f",_s,_a,_t,_e)
#define fstdma(_s, _t, _a, _e) def_store_ai_insn(fstd,8,"f",_s,_a,_t,_e)

#define def_load_insn(_insn,_tt,_s,_o,_a,_t,_e) 	\
	__asm__ __volatile__ (				\
	"1:\t" #_insn " " #_o "(" _s ",%1), %0\n\t"	\
	ASM_EXCEPTIONTABLE_ENTRY(1b,_e)			\
	: _tt(_t) 					\
	: "r"(_a)					\
	: "r8")

#define def_store_insn(_insn,_tt,_s,_t,_o,_a,_e) 	\
	__asm__ __volatile__ (				\
	"1:\t" #_insn " %0, " #_o "(" _s ",%1)\n\t" 	\
	ASM_EXCEPTIONTABLE_ENTRY(1b,_e)			\
	: 						\
	: _tt(_t), "r"(_a)				\
	: "r8")

#define ldw(_s,_o,_a,_t,_e)	def_load_insn(ldw,"=r",_s,_o,_a,_t,_e)
#define stw(_s,_t,_o,_a,_e) 	def_store_insn(stw,"r",_s,_t,_o,_a,_e)

#ifdef  CONFIG_PREFETCH
extern inline void prefetch_src(const void *addr)
{
	__asm__("ldw 0(" s_space ",%0), %%r0" : : "r" (addr));
}

extern inline void prefetch_dst(const void *addr)
{
	__asm__("ldd 0(" d_space ",%0), %%r0" : : "r" (addr));
}
#else
#define prefetch_src(addr) do { } while(0)
#define prefetch_dst(addr) do { } while(0)
#endif

/* Copy from a not-aligned src to an aligned dst, using shifts. Handles 4 words
 * per loop.  This code is derived from glibc. 
 */
static inline unsigned long copy_dstaligned(unsigned long dst, unsigned long src, unsigned long len, unsigned long o_dst, unsigned long o_src, unsigned long o_len)
{
	/* gcc complains that a2 and a3 may be uninitialized, but actually
	 * they cannot be.  Initialize a2/a3 to shut gcc up.
	 */
	register unsigned int a0, a1, a2 = 0, a3 = 0;
	int sh_1, sh_2;
	struct exception_data *d;

	/* prefetch_src((const void *)src); */

	/* Calculate how to shift a word read at the memory operation
	   aligned srcp to make it aligned for copy.  */
	sh_1 = 8 * (src % sizeof(unsigned int));
	sh_2 = 8 * sizeof(unsigned int) - sh_1;

	/* Make src aligned by rounding it down.  */
	src &= -sizeof(unsigned int);

	switch (len % 4)
	{
		case 2:
			/* a1 = ((unsigned int *) src)[0];
			   a2 = ((unsigned int *) src)[1]; */
			ldw(s_space, 0, src, a1, cda_ldw_exc);
			ldw(s_space, 4, src, a2, cda_ldw_exc);
			src -= 1 * sizeof(unsigned int);
			dst -= 3 * sizeof(unsigned int);
			len += 2;
			goto do1;
		case 3:
			/* a0 = ((unsigned int *) src)[0];
			   a1 = ((unsigned int *) src)[1]; */
			ldw(s_space, 0, src, a0, cda_ldw_exc);
			ldw(s_space, 4, src, a1, cda_ldw_exc);
			src -= 0 * sizeof(unsigned int);
			dst -= 2 * sizeof(unsigned int);
			len += 1;
			goto do2;
		case 0:
			if (len == 0)
				return 0;
			/* a3 = ((unsigned int *) src)[0];
			   a0 = ((unsigned int *) src)[1]; */
			ldw(s_space, 0, src, a3, cda_ldw_exc);
			ldw(s_space, 4, src, a0, cda_ldw_exc);
			src -=-1 * sizeof(unsigned int);
			dst -= 1 * sizeof(unsigned int);
			len += 0;
			goto do3;
		case 1:
			/* a2 = ((unsigned int *) src)[0];
			   a3 = ((unsigned int *) src)[1]; */
			ldw(s_space, 0, src, a2, cda_ldw_exc);
			ldw(s_space, 4, src, a3, cda_ldw_exc);
			src -=-2 * sizeof(unsigned int);
			dst -= 0 * sizeof(unsigned int);
			len -= 1;
			if (len == 0)
				goto do0;
			goto do4;			/* No-op.  */
	}

	do
	{
		/* prefetch_src((const void *)(src + 4 * sizeof(unsigned int))); */
do4:
		/* a0 = ((unsigned int *) src)[0]; */
		ldw(s_space, 0, src, a0, cda_ldw_exc);
		/* ((unsigned int *) dst)[0] = MERGE (a2, sh_1, a3, sh_2); */
		stw(d_space, MERGE (a2, sh_1, a3, sh_2), 0, dst, cda_stw_exc);
do3:
		/* a1 = ((unsigned int *) src)[1]; */
		ldw(s_space, 4, src, a1, cda_ldw_exc);
		/* ((unsigned int *) dst)[1] = MERGE (a3, sh_1, a0, sh_2); */
		stw(d_space, MERGE (a3, sh_1, a0, sh_2), 4, dst, cda_stw_exc);
do2:
		/* a2 = ((unsigned int *) src)[2]; */
		ldw(s_space, 8, src, a2, cda_ldw_exc);
		/* ((unsigned int *) dst)[2] = MERGE (a0, sh_1, a1, sh_2); */
		stw(d_space, MERGE (a0, sh_1, a1, sh_2), 8, dst, cda_stw_exc);
do1:
		/* a3 = ((unsigned int *) src)[3]; */
		ldw(s_space, 12, src, a3, cda_ldw_exc);
		/* ((unsigned int *) dst)[3] = MERGE (a1, sh_1, a2, sh_2); */
		stw(d_space, MERGE (a1, sh_1, a2, sh_2), 12, dst, cda_stw_exc);

		src += 4 * sizeof(unsigned int);
		dst += 4 * sizeof(unsigned int);
		len -= 4;
	}
	while (len != 0);

do0:
	/* ((unsigned int *) dst)[0] = MERGE (a2, sh_1, a3, sh_2); */
	stw(d_space, MERGE (a2, sh_1, a3, sh_2), 0, dst, cda_stw_exc);

	preserve_branch(handle_load_error);
	preserve_branch(handle_store_error);

	return 0;

handle_load_error:
	__asm__ __volatile__ ("cda_ldw_exc:\n");
	d = &__get_cpu_var(exception_data);
	DPRINTF("cda_ldw_exc: o_len=%lu fault_addr=%lu o_src=%lu ret=%lu\n",
		o_len, d->fault_addr, o_src, o_len - d->fault_addr + o_src);
	return o_len * 4 - d->fault_addr + o_src;

handle_store_error:
	__asm__ __volatile__ ("cda_stw_exc:\n");
	d = &__get_cpu_var(exception_data);
	DPRINTF("cda_stw_exc: o_len=%lu fault_addr=%lu o_dst=%lu ret=%lu\n",
		o_len, d->fault_addr, o_dst, o_len - d->fault_addr + o_dst);
	return o_len * 4 - d->fault_addr + o_dst;
}


/* Returns 0 for success, otherwise, returns number of bytes not transferred. */
unsigned long pa_memcpy(void *dstp, const void *srcp, unsigned long len)
{
	register unsigned long src, dst, t1, t2, t3;
	register unsigned char *pcs, *pcd;
	register unsigned int *pws, *pwd;
	register double *pds, *pdd;
	unsigned long ret = 0;
	unsigned long o_dst, o_src, o_len;
	struct exception_data *d;

	src = (unsigned long)srcp;
	dst = (unsigned long)dstp;
	pcs = (unsigned char *)srcp;
	pcd = (unsigned char *)dstp;

	o_dst = dst; o_src = src; o_len = len;

	/* prefetch_src((const void *)srcp); */

	if (len < THRESHOLD)
		goto byte_copy;

	/* Check alignment */
	t1 = (src ^ dst);
	if (unlikely(t1 & (sizeof(double)-1)))
		goto unaligned_copy;

	/* src and dst have same alignment. */

	/* Copy bytes till we are double-aligned. */
	t2 = src & (sizeof(double) - 1);
	if (unlikely(t2 != 0)) {
		t2 = sizeof(double) - t2;
		while (t2 && len) {
			/* *pcd++ = *pcs++; */
			ldbma(s_space, pcs, t3, pmc_load_exc);
			len--;
			stbma(d_space, t3, pcd, pmc_store_exc);
			t2--;
		}
	}

	pds = (double *)pcs;
	pdd = (double *)pcd;

#if 0
	/* Copy 8 doubles at a time */
	while (len >= 8*sizeof(double)) {
		register double r1, r2, r3, r4, r5, r6, r7, r8;
		/* prefetch_src((char *)pds + L1_CACHE_BYTES); */
		flddma(s_space, pds, r1, pmc_load_exc);
		flddma(s_space, pds, r2, pmc_load_exc);
		flddma(s_space, pds, r3, pmc_load_exc);
		flddma(s_space, pds, r4, pmc_load_exc);
		fstdma(d_space, r1, pdd, pmc_store_exc);
		fstdma(d_space, r2, pdd, pmc_store_exc);
		fstdma(d_space, r3, pdd, pmc_store_exc);
		fstdma(d_space, r4, pdd, pmc_store_exc);

#if 0
		if (L1_CACHE_BYTES <= 32)
			prefetch_src((char *)pds + L1_CACHE_BYTES);
#endif
		flddma(s_space, pds, r5, pmc_load_exc);
		flddma(s_space, pds, r6, pmc_load_exc);
		flddma(s_space, pds, r7, pmc_load_exc);
		flddma(s_space, pds, r8, pmc_load_exc);
		fstdma(d_space, r5, pdd, pmc_store_exc);
		fstdma(d_space, r6, pdd, pmc_store_exc);
		fstdma(d_space, r7, pdd, pmc_store_exc);
		fstdma(d_space, r8, pdd, pmc_store_exc);
		len -= 8*sizeof(double);
	}
#endif

	pws = (unsigned int *)pds;
	pwd = (unsigned int *)pdd;

word_copy:
	while (len >= 8*sizeof(unsigned int)) {
		register unsigned int r1,r2,r3,r4,r5,r6,r7,r8;
		/* prefetch_src((char *)pws + L1_CACHE_BYTES); */
		ldwma(s_space, pws, r1, pmc_load_exc);
		ldwma(s_space, pws, r2, pmc_load_exc);
		ldwma(s_space, pws, r3, pmc_load_exc);
		ldwma(s_space, pws, r4, pmc_load_exc);
		stwma(d_space, r1, pwd, pmc_store_exc);
		stwma(d_space, r2, pwd, pmc_store_exc);
		stwma(d_space, r3, pwd, pmc_store_exc);
		stwma(d_space, r4, pwd, pmc_store_exc);

		ldwma(s_space, pws, r5, pmc_load_exc);
		ldwma(s_space, pws, r6, pmc_load_exc);
		ldwma(s_space, pws, r7, pmc_load_exc);
		ldwma(s_space, pws, r8, pmc_load_exc);
		stwma(d_space, r5, pwd, pmc_store_exc);
		stwma(d_space, r6, pwd, pmc_store_exc);
		stwma(d_space, r7, pwd, pmc_store_exc);
		stwma(d_space, r8, pwd, pmc_store_exc);
		len -= 8*sizeof(unsigned int);
	}

	while (len >= 4*sizeof(unsigned int)) {
		register unsigned int r1,r2,r3,r4;
		ldwma(s_space, pws, r1, pmc_load_exc);
		ldwma(s_space, pws, r2, pmc_load_exc);
		ldwma(s_space, pws, r3, pmc_load_exc);
		ldwma(s_space, pws, r4, pmc_load_exc);
		stwma(d_space, r1, pwd, pmc_store_exc);
		stwma(d_space, r2, pwd, pmc_store_exc);
		stwma(d_space, r3, pwd, pmc_store_exc);
		stwma(d_space, r4, pwd, pmc_store_exc);
		len -= 4*sizeof(unsigned int);
	}

	pcs = (unsigned char *)pws;
	pcd = (unsigned char *)pwd;

byte_copy:
	while (len) {
		/* *pcd++ = *pcs++; */
		ldbma(s_space, pcs, t3, pmc_load_exc);
		stbma(d_space, t3, pcd, pmc_store_exc);
		len--;
	}

	return 0;

unaligned_copy:
	/* possibly we are aligned on a word, but not on a double... */
	if (likely(t1 & (sizeof(unsigned int)-1)) == 0) {
		t2 = src & (sizeof(unsigned int) - 1);

		if (unlikely(t2 != 0)) {
			t2 = sizeof(unsigned int) - t2;
			while (t2) {
				/* *pcd++ = *pcs++; */
				ldbma(s_space, pcs, t3, pmc_load_exc);
				stbma(d_space, t3, pcd, pmc_store_exc);
				len--;
				t2--;
			}
		}

		pws = (unsigned int *)pcs;
		pwd = (unsigned int *)pcd;
		goto word_copy;
	}

	/* Align the destination.  */
	if (unlikely((dst & (sizeof(unsigned int) - 1)) != 0)) {
		t2 = sizeof(unsigned int) - (dst & (sizeof(unsigned int) - 1));
		while (t2) {
			/* *pcd++ = *pcs++; */
			ldbma(s_space, pcs, t3, pmc_load_exc);
			stbma(d_space, t3, pcd, pmc_store_exc);
			len--;
			t2--;
		}
		dst = (unsigned long)pcd;
		src = (unsigned long)pcs;
	}

	ret = copy_dstaligned(dst, src, len / sizeof(unsigned int), 
		o_dst, o_src, o_len);
	if (ret)
		return ret;

	pcs += (len & -sizeof(unsigned int));
	pcd += (len & -sizeof(unsigned int));
	len %= sizeof(unsigned int);

	preserve_branch(handle_load_error);
	preserve_branch(handle_store_error);

	goto byte_copy;

handle_load_error:
	__asm__ __volatile__ ("pmc_load_exc:\n");
	d = &__get_cpu_var(exception_data);
	DPRINTF("pmc_load_exc: o_len=%lu fault_addr=%lu o_src=%lu ret=%lu\n",
		o_len, d->fault_addr, o_src, o_len - d->fault_addr + o_src);
	return o_len - d->fault_addr + o_src;

handle_store_error:
	__asm__ __volatile__ ("pmc_store_exc:\n");
	d = &__get_cpu_var(exception_data);
	DPRINTF("pmc_store_exc: o_len=%lu fault_addr=%lu o_dst=%lu ret=%lu\n",
		o_len, d->fault_addr, o_dst, o_len - d->fault_addr + o_dst);
	return o_len - d->fault_addr + o_dst;
}

#ifdef __KERNEL__
unsigned long copy_to_user(void __user *dst, const void *src, unsigned long len)
{
	mtsp(get_kernel_space(), 1);
	mtsp(get_user_space(), 2);
	return pa_memcpy((void __force *)dst, src, len);
}

unsigned long copy_from_user(void *dst, const void __user *src, unsigned long len)
{
	mtsp(get_user_space(), 1);
	mtsp(get_kernel_space(), 2);
	return pa_memcpy(dst, (void __force *)src, len);
}

unsigned long copy_in_user(void __user *dst, const void __user *src, unsigned long len)
{
	mtsp(get_user_space(), 1);
	mtsp(get_user_space(), 2);
	return pa_memcpy((void __force *)dst, (void __force *)src, len);
}


void * memcpy(void * dst,const void *src, size_t count)
{
	mtsp(get_kernel_space(), 1);
	mtsp(get_kernel_space(), 2);
	pa_memcpy(dst, src, count);
	return dst;
}

EXPORT_SYMBOL(copy_to_user);
EXPORT_SYMBOL(copy_from_user);
EXPORT_SYMBOL(copy_in_user);
EXPORT_SYMBOL(memcpy);
#endif