summaryrefslogtreecommitdiff
path: root/arch/tile/lib/memcpy_64.c
blob: c79b8e7c6828bd384e0c354dccf72553ef1c9536 (plain)
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
/*
 * Copyright 2011 Tilera Corporation. All Rights Reserved.
 *
 *   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, version 2.
 *
 *   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, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
/* EXPORT_SYMBOL() is in arch/tile/lib/exports.c since this should be asm. */

/* Must be 8 bytes in size. */
#define word_t uint64_t

#if CHIP_L2_LINE_SIZE() != 64 && CHIP_L2_LINE_SIZE() != 128
#error "Assumes 64 or 128 byte line size"
#endif

/* How many cache lines ahead should we prefetch? */
#define PREFETCH_LINES_AHEAD 3

/*
 * Provide "base versions" of load and store for the normal code path.
 * The kernel provides other versions for userspace copies.
 */
#define ST(p, v) (*(p) = (v))
#define LD(p) (*(p))

#ifndef USERCOPY_FUNC
#define ST1 ST
#define ST2 ST
#define ST4 ST
#define ST8 ST
#define LD1 LD
#define LD2 LD
#define LD4 LD
#define LD8 LD
#define RETVAL dstv
void *memcpy(void *__restrict dstv, const void *__restrict srcv, size_t n)
#else
/*
 * Special kernel version will provide implementation of the LDn/STn
 * macros to return a count of uncopied bytes due to mm fault.
 */
#define RETVAL 0
int USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
#endif
{
	char *__restrict dst1 = (char *)dstv;
	const char *__restrict src1 = (const char *)srcv;
	const char *__restrict src1_end;
	const char *__restrict prefetch;
	word_t *__restrict dst8;    /* 8-byte pointer to destination memory. */
	word_t final; /* Final bytes to write to trailing word, if any */
	long i;

	if (n < 16) {
		for (; n; n--)
			ST1(dst1++, LD1(src1++));
		return RETVAL;
	}

	/*
	 * Locate the end of source memory we will copy.  Don't
	 * prefetch past this.
	 */
	src1_end = src1 + n - 1;

	/* Prefetch ahead a few cache lines, but not past the end. */
	prefetch = src1;
	for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
		__insn_prefetch(prefetch);
		prefetch += CHIP_L2_LINE_SIZE();
		prefetch = (prefetch > src1_end) ? prefetch : src1;
	}

	/* Copy bytes until dst is word-aligned. */
	for (; (uintptr_t)dst1 & (sizeof(word_t) - 1); n--)
		ST1(dst1++, LD1(src1++));

	/* 8-byte pointer to destination memory. */
	dst8 = (word_t *)dst1;

	if (__builtin_expect((uintptr_t)src1 & (sizeof(word_t) - 1), 0)) {
		/*
		 * Misaligned copy.  Copy 8 bytes at a time, but don't
		 * bother with other fanciness.
		 *
		 * TODO: Consider prefetching and using wh64 as well.
		 */

		/* Create an aligned src8. */
		const word_t *__restrict src8 =
			(const word_t *)((uintptr_t)src1 & -sizeof(word_t));
		word_t b;

		word_t a = LD8(src8++);
		for (; n >= sizeof(word_t); n -= sizeof(word_t)) {
			b = LD8(src8++);
			a = __insn_dblalign(a, b, src1);
			ST8(dst8++, a);
			a = b;
		}

		if (n == 0)
			return RETVAL;

		b = ((const char *)src8 <= src1_end) ? *src8 : 0;

		/*
		 * Final source bytes to write to trailing partial
		 * word, if any.
		 */
		final = __insn_dblalign(a, b, src1);
	} else {
		/* Aligned copy. */

		const word_t* __restrict src8 = (const word_t *)src1;

		/* src8 and dst8 are both word-aligned. */
		if (n >= CHIP_L2_LINE_SIZE()) {
			/* Copy until 'dst' is cache-line-aligned. */
			for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
			     n -= sizeof(word_t))
				ST8(dst8++, LD8(src8++));

			for (; n >= CHIP_L2_LINE_SIZE(); ) {
				__insn_wh64(dst8);

				/*
				 * Prefetch and advance to next line
				 * to prefetch, but don't go past the end
				 */
				__insn_prefetch(prefetch);
				prefetch += CHIP_L2_LINE_SIZE();
				prefetch = (prefetch > src1_end) ? prefetch :
					(const char *)src8;

				/*
				 * Copy an entire cache line.  Manually
				 * unrolled to avoid idiosyncracies of
				 * compiler unrolling.
				 */
#define COPY_WORD(offset) ({ ST8(dst8+offset, LD8(src8+offset)); n -= 8; })
				COPY_WORD(0);
				COPY_WORD(1);
				COPY_WORD(2);
				COPY_WORD(3);
				COPY_WORD(4);
				COPY_WORD(5);
				COPY_WORD(6);
				COPY_WORD(7);
#if CHIP_L2_LINE_SIZE() == 128
				COPY_WORD(8);
				COPY_WORD(9);
				COPY_WORD(10);
				COPY_WORD(11);
				COPY_WORD(12);
				COPY_WORD(13);
				COPY_WORD(14);
				COPY_WORD(15);
#elif CHIP_L2_LINE_SIZE() != 64
# error Fix code that assumes particular L2 cache line sizes
#endif

				dst8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
				src8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
			}
		}

		for (; n >= sizeof(word_t); n -= sizeof(word_t))
			ST8(dst8++, LD8(src8++));

		if (__builtin_expect(n == 0, 1))
			return RETVAL;

		final = LD8(src8);
	}

	/* n != 0 if we get here.  Write out any trailing bytes. */
	dst1 = (char *)dst8;
#ifndef __BIG_ENDIAN__
	if (n & 4) {
		ST4((uint32_t *)dst1, final);
		dst1 += 4;
		final >>= 32;
		n &= 3;
	}
	if (n & 2) {
		ST2((uint16_t *)dst1, final);
		dst1 += 2;
		final >>= 16;
		n &= 1;
	}
	if (n)
		ST1((uint8_t *)dst1, final);
#else
	if (n & 4) {
		ST4((uint32_t *)dst1, final >> 32);
		dst1 += 4;
        }
        else
        {
		final >>= 32;
        }
	if (n & 2) {
		ST2((uint16_t *)dst1, final >> 16);
		dst1 += 2;
        }
        else
        {
		final >>= 16;
        }
	if (n & 1)
		ST1((uint8_t *)dst1, final >> 8);
#endif

	return RETVAL;
}

#ifdef USERCOPY_FUNC
#undef ST1
#undef ST2
#undef ST4
#undef ST8
#undef LD1
#undef LD2
#undef LD4
#undef LD8
#undef USERCOPY_FUNC
#endif