1 /*
2 * Copyright 2011 Tilera Corporation. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
12 * more details.
13 */
14
15 #include <linux/types.h>
16 #include <linux/string.h>
17 #include <linux/module.h>
18 /* EXPORT_SYMBOL() is in arch/tile/lib/exports.c since this should be asm. */
19
20 /* Must be 8 bytes in size. */
21 #define op_t uint64_t
22
23 /* Threshold value for when to enter the unrolled loops. */
24 #define OP_T_THRES 16
25
26 #if CHIP_L2_LINE_SIZE() != 64
27 #error "Assumes 64 byte line size"
28 #endif
29
30 /* How many cache lines ahead should we prefetch? */
31 #define PREFETCH_LINES_AHEAD 4
32
33 /*
34 * Provide "base versions" of load and store for the normal code path.
35 * The kernel provides other versions for userspace copies.
36 */
37 #define ST(p, v) (*(p) = (v))
38 #define LD(p) (*(p))
39
40 #ifndef USERCOPY_FUNC
41 #define ST1 ST
42 #define ST2 ST
43 #define ST4 ST
44 #define ST8 ST
45 #define LD1 LD
46 #define LD2 LD
47 #define LD4 LD
48 #define LD8 LD
49 #define RETVAL dstv
memcpy(void * __restrict dstv,const void * __restrict srcv,size_t n)50 void *memcpy(void *__restrict dstv, const void *__restrict srcv, size_t n)
51 #else
52 /*
53 * Special kernel version will provide implementation of the LDn/STn
54 * macros to return a count of uncopied bytes due to mm fault.
55 */
56 #define RETVAL 0
57 int __attribute__((optimize("omit-frame-pointer")))
58 USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
59 #endif
60 {
61 char *__restrict dst1 = (char *)dstv;
62 const char *__restrict src1 = (const char *)srcv;
63 const char *__restrict src1_end;
64 const char *__restrict prefetch;
65 op_t *__restrict dst8; /* 8-byte pointer to destination memory. */
66 op_t final; /* Final bytes to write to trailing word, if any */
67 long i;
68
69 if (n < 16) {
70 for (; n; n--)
71 ST1(dst1++, LD1(src1++));
72 return RETVAL;
73 }
74
75 /*
76 * Locate the end of source memory we will copy. Don't
77 * prefetch past this.
78 */
79 src1_end = src1 + n - 1;
80
81 /* Prefetch ahead a few cache lines, but not past the end. */
82 prefetch = src1;
83 for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
84 __insn_prefetch(prefetch);
85 prefetch += CHIP_L2_LINE_SIZE();
86 prefetch = (prefetch < src1_end) ? prefetch : src1;
87 }
88
89 /* Copy bytes until dst is word-aligned. */
90 for (; (uintptr_t)dst1 & (sizeof(op_t) - 1); n--)
91 ST1(dst1++, LD1(src1++));
92
93 /* 8-byte pointer to destination memory. */
94 dst8 = (op_t *)dst1;
95
96 if (__builtin_expect((uintptr_t)src1 & (sizeof(op_t) - 1), 0)) {
97 /* Unaligned copy. */
98
99 op_t tmp0 = 0, tmp1 = 0, tmp2, tmp3;
100 const op_t *src8 = (const op_t *) ((uintptr_t)src1 &
101 -sizeof(op_t));
102 const void *srci = (void *)src1;
103 int m;
104
105 m = (CHIP_L2_LINE_SIZE() << 2) -
106 (((uintptr_t)dst8) & ((CHIP_L2_LINE_SIZE() << 2) - 1));
107 m = (n < m) ? n : m;
108 m /= sizeof(op_t);
109
110 /* Copy until 'dst' is cache-line-aligned. */
111 n -= (sizeof(op_t) * m);
112
113 switch (m % 4) {
114 case 0:
115 if (__builtin_expect(!m, 0))
116 goto _M0;
117 tmp1 = LD8(src8++);
118 tmp2 = LD8(src8++);
119 goto _8B3;
120 case 2:
121 m += 2;
122 tmp3 = LD8(src8++);
123 tmp0 = LD8(src8++);
124 goto _8B1;
125 case 3:
126 m += 1;
127 tmp2 = LD8(src8++);
128 tmp3 = LD8(src8++);
129 goto _8B2;
130 case 1:
131 m--;
132 tmp0 = LD8(src8++);
133 tmp1 = LD8(src8++);
134 if (__builtin_expect(!m, 0))
135 goto _8B0;
136 }
137
138 do {
139 tmp2 = LD8(src8++);
140 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
141 ST8(dst8++, tmp0);
142 _8B3:
143 tmp3 = LD8(src8++);
144 tmp1 = __insn_dblalign(tmp1, tmp2, srci);
145 ST8(dst8++, tmp1);
146 _8B2:
147 tmp0 = LD8(src8++);
148 tmp2 = __insn_dblalign(tmp2, tmp3, srci);
149 ST8(dst8++, tmp2);
150 _8B1:
151 tmp1 = LD8(src8++);
152 tmp3 = __insn_dblalign(tmp3, tmp0, srci);
153 ST8(dst8++, tmp3);
154 m -= 4;
155 } while (m);
156
157 _8B0:
158 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
159 ST8(dst8++, tmp0);
160 src8--;
161
162 _M0:
163 if (__builtin_expect(n >= CHIP_L2_LINE_SIZE(), 0)) {
164 op_t tmp4, tmp5, tmp6, tmp7, tmp8;
165
166 prefetch = ((const char *)src8) +
167 CHIP_L2_LINE_SIZE() * PREFETCH_LINES_AHEAD;
168
169 for (tmp0 = LD8(src8++); n >= CHIP_L2_LINE_SIZE();
170 n -= CHIP_L2_LINE_SIZE()) {
171 /* Prefetch and advance to next line to
172 prefetch, but don't go past the end. */
173 __insn_prefetch(prefetch);
174
175 /* Make sure prefetch got scheduled
176 earlier. */
177 __asm__ ("" : : : "memory");
178
179 prefetch += CHIP_L2_LINE_SIZE();
180 prefetch = (prefetch < src1_end) ? prefetch :
181 (const char *) src8;
182
183 tmp1 = LD8(src8++);
184 tmp2 = LD8(src8++);
185 tmp3 = LD8(src8++);
186 tmp4 = LD8(src8++);
187 tmp5 = LD8(src8++);
188 tmp6 = LD8(src8++);
189 tmp7 = LD8(src8++);
190 tmp8 = LD8(src8++);
191
192 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
193 tmp1 = __insn_dblalign(tmp1, tmp2, srci);
194 tmp2 = __insn_dblalign(tmp2, tmp3, srci);
195 tmp3 = __insn_dblalign(tmp3, tmp4, srci);
196 tmp4 = __insn_dblalign(tmp4, tmp5, srci);
197 tmp5 = __insn_dblalign(tmp5, tmp6, srci);
198 tmp6 = __insn_dblalign(tmp6, tmp7, srci);
199 tmp7 = __insn_dblalign(tmp7, tmp8, srci);
200
201 __insn_wh64(dst8);
202
203 ST8(dst8++, tmp0);
204 ST8(dst8++, tmp1);
205 ST8(dst8++, tmp2);
206 ST8(dst8++, tmp3);
207 ST8(dst8++, tmp4);
208 ST8(dst8++, tmp5);
209 ST8(dst8++, tmp6);
210 ST8(dst8++, tmp7);
211
212 tmp0 = tmp8;
213 }
214 src8--;
215 }
216
217 /* Copy the rest 8-byte chunks. */
218 if (n >= sizeof(op_t)) {
219 tmp0 = LD8(src8++);
220 for (; n >= sizeof(op_t); n -= sizeof(op_t)) {
221 tmp1 = LD8(src8++);
222 tmp0 = __insn_dblalign(tmp0, tmp1, srci);
223 ST8(dst8++, tmp0);
224 tmp0 = tmp1;
225 }
226 src8--;
227 }
228
229 if (n == 0)
230 return RETVAL;
231
232 tmp0 = LD8(src8++);
233 tmp1 = ((const char *)src8 <= src1_end)
234 ? LD8((op_t *)src8) : 0;
235 final = __insn_dblalign(tmp0, tmp1, srci);
236
237 } else {
238 /* Aligned copy. */
239
240 const op_t *__restrict src8 = (const op_t *)src1;
241
242 /* src8 and dst8 are both word-aligned. */
243 if (n >= CHIP_L2_LINE_SIZE()) {
244 /* Copy until 'dst' is cache-line-aligned. */
245 for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
246 n -= sizeof(op_t))
247 ST8(dst8++, LD8(src8++));
248
249 for (; n >= CHIP_L2_LINE_SIZE(); ) {
250 op_t tmp0, tmp1, tmp2, tmp3;
251 op_t tmp4, tmp5, tmp6, tmp7;
252
253 /*
254 * Prefetch and advance to next line
255 * to prefetch, but don't go past the
256 * end.
257 */
258 __insn_prefetch(prefetch);
259
260 /* Make sure prefetch got scheduled
261 earlier. */
262 __asm__ ("" : : : "memory");
263
264 prefetch += CHIP_L2_LINE_SIZE();
265 prefetch = (prefetch < src1_end) ? prefetch :
266 (const char *)src8;
267
268 /*
269 * Do all the loads before wh64. This
270 * is necessary if [src8, src8+7] and
271 * [dst8, dst8+7] share the same cache
272 * line and dst8 <= src8, as can be
273 * the case when called from memmove,
274 * or with code tested on x86 whose
275 * memcpy always works with forward
276 * copies.
277 */
278 tmp0 = LD8(src8++);
279 tmp1 = LD8(src8++);
280 tmp2 = LD8(src8++);
281 tmp3 = LD8(src8++);
282 tmp4 = LD8(src8++);
283 tmp5 = LD8(src8++);
284 tmp6 = LD8(src8++);
285 tmp7 = LD8(src8++);
286
287 /* wh64 and wait for tmp7 load completion. */
288 __asm__ ("move %0, %0; wh64 %1\n"
289 : : "r"(tmp7), "r"(dst8));
290
291 ST8(dst8++, tmp0);
292 ST8(dst8++, tmp1);
293 ST8(dst8++, tmp2);
294 ST8(dst8++, tmp3);
295 ST8(dst8++, tmp4);
296 ST8(dst8++, tmp5);
297 ST8(dst8++, tmp6);
298 ST8(dst8++, tmp7);
299
300 n -= CHIP_L2_LINE_SIZE();
301 }
302 #if CHIP_L2_LINE_SIZE() != 64
303 # error "Fix code that assumes particular L2 cache line size."
304 #endif
305 }
306
307 for (; n >= sizeof(op_t); n -= sizeof(op_t))
308 ST8(dst8++, LD8(src8++));
309
310 if (__builtin_expect(n == 0, 1))
311 return RETVAL;
312
313 final = LD8(src8);
314 }
315
316 /* n != 0 if we get here. Write out any trailing bytes. */
317 dst1 = (char *)dst8;
318 #ifndef __BIG_ENDIAN__
319 if (n & 4) {
320 ST4((uint32_t *)dst1, final);
321 dst1 += 4;
322 final >>= 32;
323 n &= 3;
324 }
325 if (n & 2) {
326 ST2((uint16_t *)dst1, final);
327 dst1 += 2;
328 final >>= 16;
329 n &= 1;
330 }
331 if (n)
332 ST1((uint8_t *)dst1, final);
333 #else
334 if (n & 4) {
335 ST4((uint32_t *)dst1, final >> 32);
336 dst1 += 4;
337 }
338 else
339 {
340 final >>= 32;
341 }
342 if (n & 2) {
343 ST2((uint16_t *)dst1, final >> 16);
344 dst1 += 2;
345 }
346 else
347 {
348 final >>= 16;
349 }
350 if (n & 1)
351 ST1((uint8_t *)dst1, final >> 8);
352 #endif
353
354 return RETVAL;
355 }
356
357 #ifdef USERCOPY_FUNC
358 #undef ST1
359 #undef ST2
360 #undef ST4
361 #undef ST8
362 #undef LD1
363 #undef LD2
364 #undef LD4
365 #undef LD8
366 #undef USERCOPY_FUNC
367 #endif
368