1 /*
2 * Optimized memory copy routines.
3 *
4 * Copyright (C) 2004 Randolph Chung <tausq@debian.org>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2, or (at your option)
9 * any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 *
20 * Portions derived from the GNU C Library
21 * Copyright (C) 1991, 1997, 2003 Free Software Foundation, Inc.
22 *
23 * Several strategies are tried to try to get the best performance for various
24 * conditions. In the optimal case, we copy 64-bytes in an unrolled loop using
25 * fp regs. This is followed by loops that copy 32- or 16-bytes at a time using
26 * general registers. Unaligned copies are handled either by aligning the
27 * destination and then using shift-and-write method, or in a few cases by
28 * falling back to a byte-at-a-time copy.
29 *
30 * I chose to implement this in C because it is easier to maintain and debug,
31 * and in my experiments it appears that the C code generated by gcc (3.3/3.4
32 * at the time of writing) is fairly optimal. Unfortunately some of the
33 * semantics of the copy routine (exception handling) is difficult to express
34 * in C, so we have to play some tricks to get it to work.
35 *
36 * All the loads and stores are done via explicit asm() code in order to use
37 * the right space registers.
38 *
39 * Testing with various alignments and buffer sizes shows that this code is
40 * often >10x faster than a simple byte-at-a-time copy, even for strangely
41 * aligned operands. It is interesting to note that the glibc version
42 * of memcpy (written in C) is actually quite fast already. This routine is
43 * able to beat it by 30-40% for aligned copies because of the loop unrolling,
44 * but in some cases the glibc version is still slightly faster. This lends
45 * more credibility that gcc can generate very good code as long as we are
46 * careful.
47 *
48 * TODO:
49 * - cache prefetching needs more experimentation to get optimal settings
50 * - try not to use the post-increment address modifiers; they create additional
51 * interlocks
52 * - replace byte-copy loops with stybs sequences
53 */
54
55 #ifdef __KERNEL__
56 #include <linux/module.h>
57 #include <linux/compiler.h>
58 #include <asm/uaccess.h>
59 #define s_space "%%sr1"
60 #define d_space "%%sr2"
61 #else
62 #include "memcpy.h"
63 #define s_space "%%sr0"
64 #define d_space "%%sr0"
65 #define pa_memcpy new2_copy
66 #endif
67
68 DECLARE_PER_CPU(struct exception_data, exception_data);
69
70 #define preserve_branch(label) do { \
71 volatile int dummy; \
72 /* The following branch is never taken, it's just here to */ \
73 /* prevent gcc from optimizing away our exception code. */ \
74 if (unlikely(dummy != dummy)) \
75 goto label; \
76 } while (0)
77
78 #define get_user_space() (segment_eq(get_fs(), KERNEL_DS) ? 0 : mfsp(3))
79 #define get_kernel_space() (0)
80
81 #define MERGE(w0, sh_1, w1, sh_2) ({ \
82 unsigned int _r; \
83 asm volatile ( \
84 "mtsar %3\n" \
85 "shrpw %1, %2, %%sar, %0\n" \
86 : "=r"(_r) \
87 : "r"(w0), "r"(w1), "r"(sh_2) \
88 ); \
89 _r; \
90 })
91 #define THRESHOLD 16
92
93 #ifdef DEBUG_MEMCPY
94 #define DPRINTF(fmt, args...) do { printk(KERN_DEBUG "%s:%d:%s ", __FILE__, __LINE__, __func__ ); printk(KERN_DEBUG fmt, ##args ); } while (0)
95 #else
96 #define DPRINTF(fmt, args...)
97 #endif
98
99 #define def_load_ai_insn(_insn,_sz,_tt,_s,_a,_t,_e) \
100 __asm__ __volatile__ ( \
101 "1:\t" #_insn ",ma " #_sz "(" _s ",%1), %0\n\t" \
102 ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
103 : _tt(_t), "+r"(_a) \
104 : \
105 : "r8")
106
107 #define def_store_ai_insn(_insn,_sz,_tt,_s,_a,_t,_e) \
108 __asm__ __volatile__ ( \
109 "1:\t" #_insn ",ma %1, " #_sz "(" _s ",%0)\n\t" \
110 ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
111 : "+r"(_a) \
112 : _tt(_t) \
113 : "r8")
114
115 #define ldbma(_s, _a, _t, _e) def_load_ai_insn(ldbs,1,"=r",_s,_a,_t,_e)
116 #define stbma(_s, _t, _a, _e) def_store_ai_insn(stbs,1,"r",_s,_a,_t,_e)
117 #define ldwma(_s, _a, _t, _e) def_load_ai_insn(ldw,4,"=r",_s,_a,_t,_e)
118 #define stwma(_s, _t, _a, _e) def_store_ai_insn(stw,4,"r",_s,_a,_t,_e)
119 #define flddma(_s, _a, _t, _e) def_load_ai_insn(fldd,8,"=f",_s,_a,_t,_e)
120 #define fstdma(_s, _t, _a, _e) def_store_ai_insn(fstd,8,"f",_s,_a,_t,_e)
121
122 #define def_load_insn(_insn,_tt,_s,_o,_a,_t,_e) \
123 __asm__ __volatile__ ( \
124 "1:\t" #_insn " " #_o "(" _s ",%1), %0\n\t" \
125 ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
126 : _tt(_t) \
127 : "r"(_a) \
128 : "r8")
129
130 #define def_store_insn(_insn,_tt,_s,_t,_o,_a,_e) \
131 __asm__ __volatile__ ( \
132 "1:\t" #_insn " %0, " #_o "(" _s ",%1)\n\t" \
133 ASM_EXCEPTIONTABLE_ENTRY(1b,_e) \
134 : \
135 : _tt(_t), "r"(_a) \
136 : "r8")
137
138 #define ldw(_s,_o,_a,_t,_e) def_load_insn(ldw,"=r",_s,_o,_a,_t,_e)
139 #define stw(_s,_t,_o,_a,_e) def_store_insn(stw,"r",_s,_t,_o,_a,_e)
140
141 #ifdef CONFIG_PREFETCH
prefetch_src(const void * addr)142 static inline void prefetch_src(const void *addr)
143 {
144 __asm__("ldw 0(" s_space ",%0), %%r0" : : "r" (addr));
145 }
146
prefetch_dst(const void * addr)147 static inline void prefetch_dst(const void *addr)
148 {
149 __asm__("ldd 0(" d_space ",%0), %%r0" : : "r" (addr));
150 }
151 #else
152 #define prefetch_src(addr) do { } while(0)
153 #define prefetch_dst(addr) do { } while(0)
154 #endif
155
156 /* Copy from a not-aligned src to an aligned dst, using shifts. Handles 4 words
157 * per loop. This code is derived from glibc.
158 */
copy_dstaligned(unsigned long dst,unsigned long src,unsigned long len,unsigned long o_dst,unsigned long o_src,unsigned long o_len)159 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)
160 {
161 /* gcc complains that a2 and a3 may be uninitialized, but actually
162 * they cannot be. Initialize a2/a3 to shut gcc up.
163 */
164 register unsigned int a0, a1, a2 = 0, a3 = 0;
165 int sh_1, sh_2;
166 struct exception_data *d;
167
168 /* prefetch_src((const void *)src); */
169
170 /* Calculate how to shift a word read at the memory operation
171 aligned srcp to make it aligned for copy. */
172 sh_1 = 8 * (src % sizeof(unsigned int));
173 sh_2 = 8 * sizeof(unsigned int) - sh_1;
174
175 /* Make src aligned by rounding it down. */
176 src &= -sizeof(unsigned int);
177
178 switch (len % 4)
179 {
180 case 2:
181 /* a1 = ((unsigned int *) src)[0];
182 a2 = ((unsigned int *) src)[1]; */
183 ldw(s_space, 0, src, a1, cda_ldw_exc);
184 ldw(s_space, 4, src, a2, cda_ldw_exc);
185 src -= 1 * sizeof(unsigned int);
186 dst -= 3 * sizeof(unsigned int);
187 len += 2;
188 goto do1;
189 case 3:
190 /* a0 = ((unsigned int *) src)[0];
191 a1 = ((unsigned int *) src)[1]; */
192 ldw(s_space, 0, src, a0, cda_ldw_exc);
193 ldw(s_space, 4, src, a1, cda_ldw_exc);
194 src -= 0 * sizeof(unsigned int);
195 dst -= 2 * sizeof(unsigned int);
196 len += 1;
197 goto do2;
198 case 0:
199 if (len == 0)
200 return 0;
201 /* a3 = ((unsigned int *) src)[0];
202 a0 = ((unsigned int *) src)[1]; */
203 ldw(s_space, 0, src, a3, cda_ldw_exc);
204 ldw(s_space, 4, src, a0, cda_ldw_exc);
205 src -=-1 * sizeof(unsigned int);
206 dst -= 1 * sizeof(unsigned int);
207 len += 0;
208 goto do3;
209 case 1:
210 /* a2 = ((unsigned int *) src)[0];
211 a3 = ((unsigned int *) src)[1]; */
212 ldw(s_space, 0, src, a2, cda_ldw_exc);
213 ldw(s_space, 4, src, a3, cda_ldw_exc);
214 src -=-2 * sizeof(unsigned int);
215 dst -= 0 * sizeof(unsigned int);
216 len -= 1;
217 if (len == 0)
218 goto do0;
219 goto do4; /* No-op. */
220 }
221
222 do
223 {
224 /* prefetch_src((const void *)(src + 4 * sizeof(unsigned int))); */
225 do4:
226 /* a0 = ((unsigned int *) src)[0]; */
227 ldw(s_space, 0, src, a0, cda_ldw_exc);
228 /* ((unsigned int *) dst)[0] = MERGE (a2, sh_1, a3, sh_2); */
229 stw(d_space, MERGE (a2, sh_1, a3, sh_2), 0, dst, cda_stw_exc);
230 do3:
231 /* a1 = ((unsigned int *) src)[1]; */
232 ldw(s_space, 4, src, a1, cda_ldw_exc);
233 /* ((unsigned int *) dst)[1] = MERGE (a3, sh_1, a0, sh_2); */
234 stw(d_space, MERGE (a3, sh_1, a0, sh_2), 4, dst, cda_stw_exc);
235 do2:
236 /* a2 = ((unsigned int *) src)[2]; */
237 ldw(s_space, 8, src, a2, cda_ldw_exc);
238 /* ((unsigned int *) dst)[2] = MERGE (a0, sh_1, a1, sh_2); */
239 stw(d_space, MERGE (a0, sh_1, a1, sh_2), 8, dst, cda_stw_exc);
240 do1:
241 /* a3 = ((unsigned int *) src)[3]; */
242 ldw(s_space, 12, src, a3, cda_ldw_exc);
243 /* ((unsigned int *) dst)[3] = MERGE (a1, sh_1, a2, sh_2); */
244 stw(d_space, MERGE (a1, sh_1, a2, sh_2), 12, dst, cda_stw_exc);
245
246 src += 4 * sizeof(unsigned int);
247 dst += 4 * sizeof(unsigned int);
248 len -= 4;
249 }
250 while (len != 0);
251
252 do0:
253 /* ((unsigned int *) dst)[0] = MERGE (a2, sh_1, a3, sh_2); */
254 stw(d_space, MERGE (a2, sh_1, a3, sh_2), 0, dst, cda_stw_exc);
255
256 preserve_branch(handle_load_error);
257 preserve_branch(handle_store_error);
258
259 return 0;
260
261 handle_load_error:
262 __asm__ __volatile__ ("cda_ldw_exc:\n");
263 d = &__get_cpu_var(exception_data);
264 DPRINTF("cda_ldw_exc: o_len=%lu fault_addr=%lu o_src=%lu ret=%lu\n",
265 o_len, d->fault_addr, o_src, o_len - d->fault_addr + o_src);
266 return o_len * 4 - d->fault_addr + o_src;
267
268 handle_store_error:
269 __asm__ __volatile__ ("cda_stw_exc:\n");
270 d = &__get_cpu_var(exception_data);
271 DPRINTF("cda_stw_exc: o_len=%lu fault_addr=%lu o_dst=%lu ret=%lu\n",
272 o_len, d->fault_addr, o_dst, o_len - d->fault_addr + o_dst);
273 return o_len * 4 - d->fault_addr + o_dst;
274 }
275
276
277 /* Returns 0 for success, otherwise, returns number of bytes not transferred. */
pa_memcpy(void * dstp,const void * srcp,unsigned long len)278 static unsigned long pa_memcpy(void *dstp, const void *srcp, unsigned long len)
279 {
280 register unsigned long src, dst, t1, t2, t3;
281 register unsigned char *pcs, *pcd;
282 register unsigned int *pws, *pwd;
283 register double *pds, *pdd;
284 unsigned long ret = 0;
285 unsigned long o_dst, o_src, o_len;
286 struct exception_data *d;
287
288 src = (unsigned long)srcp;
289 dst = (unsigned long)dstp;
290 pcs = (unsigned char *)srcp;
291 pcd = (unsigned char *)dstp;
292
293 o_dst = dst; o_src = src; o_len = len;
294
295 /* prefetch_src((const void *)srcp); */
296
297 if (len < THRESHOLD)
298 goto byte_copy;
299
300 /* Check alignment */
301 t1 = (src ^ dst);
302 if (unlikely(t1 & (sizeof(double)-1)))
303 goto unaligned_copy;
304
305 /* src and dst have same alignment. */
306
307 /* Copy bytes till we are double-aligned. */
308 t2 = src & (sizeof(double) - 1);
309 if (unlikely(t2 != 0)) {
310 t2 = sizeof(double) - t2;
311 while (t2 && len) {
312 /* *pcd++ = *pcs++; */
313 ldbma(s_space, pcs, t3, pmc_load_exc);
314 len--;
315 stbma(d_space, t3, pcd, pmc_store_exc);
316 t2--;
317 }
318 }
319
320 pds = (double *)pcs;
321 pdd = (double *)pcd;
322
323 #if 0
324 /* Copy 8 doubles at a time */
325 while (len >= 8*sizeof(double)) {
326 register double r1, r2, r3, r4, r5, r6, r7, r8;
327 /* prefetch_src((char *)pds + L1_CACHE_BYTES); */
328 flddma(s_space, pds, r1, pmc_load_exc);
329 flddma(s_space, pds, r2, pmc_load_exc);
330 flddma(s_space, pds, r3, pmc_load_exc);
331 flddma(s_space, pds, r4, pmc_load_exc);
332 fstdma(d_space, r1, pdd, pmc_store_exc);
333 fstdma(d_space, r2, pdd, pmc_store_exc);
334 fstdma(d_space, r3, pdd, pmc_store_exc);
335 fstdma(d_space, r4, pdd, pmc_store_exc);
336
337 #if 0
338 if (L1_CACHE_BYTES <= 32)
339 prefetch_src((char *)pds + L1_CACHE_BYTES);
340 #endif
341 flddma(s_space, pds, r5, pmc_load_exc);
342 flddma(s_space, pds, r6, pmc_load_exc);
343 flddma(s_space, pds, r7, pmc_load_exc);
344 flddma(s_space, pds, r8, pmc_load_exc);
345 fstdma(d_space, r5, pdd, pmc_store_exc);
346 fstdma(d_space, r6, pdd, pmc_store_exc);
347 fstdma(d_space, r7, pdd, pmc_store_exc);
348 fstdma(d_space, r8, pdd, pmc_store_exc);
349 len -= 8*sizeof(double);
350 }
351 #endif
352
353 pws = (unsigned int *)pds;
354 pwd = (unsigned int *)pdd;
355
356 word_copy:
357 while (len >= 8*sizeof(unsigned int)) {
358 register unsigned int r1,r2,r3,r4,r5,r6,r7,r8;
359 /* prefetch_src((char *)pws + L1_CACHE_BYTES); */
360 ldwma(s_space, pws, r1, pmc_load_exc);
361 ldwma(s_space, pws, r2, pmc_load_exc);
362 ldwma(s_space, pws, r3, pmc_load_exc);
363 ldwma(s_space, pws, r4, pmc_load_exc);
364 stwma(d_space, r1, pwd, pmc_store_exc);
365 stwma(d_space, r2, pwd, pmc_store_exc);
366 stwma(d_space, r3, pwd, pmc_store_exc);
367 stwma(d_space, r4, pwd, pmc_store_exc);
368
369 ldwma(s_space, pws, r5, pmc_load_exc);
370 ldwma(s_space, pws, r6, pmc_load_exc);
371 ldwma(s_space, pws, r7, pmc_load_exc);
372 ldwma(s_space, pws, r8, pmc_load_exc);
373 stwma(d_space, r5, pwd, pmc_store_exc);
374 stwma(d_space, r6, pwd, pmc_store_exc);
375 stwma(d_space, r7, pwd, pmc_store_exc);
376 stwma(d_space, r8, pwd, pmc_store_exc);
377 len -= 8*sizeof(unsigned int);
378 }
379
380 while (len >= 4*sizeof(unsigned int)) {
381 register unsigned int r1,r2,r3,r4;
382 ldwma(s_space, pws, r1, pmc_load_exc);
383 ldwma(s_space, pws, r2, pmc_load_exc);
384 ldwma(s_space, pws, r3, pmc_load_exc);
385 ldwma(s_space, pws, r4, pmc_load_exc);
386 stwma(d_space, r1, pwd, pmc_store_exc);
387 stwma(d_space, r2, pwd, pmc_store_exc);
388 stwma(d_space, r3, pwd, pmc_store_exc);
389 stwma(d_space, r4, pwd, pmc_store_exc);
390 len -= 4*sizeof(unsigned int);
391 }
392
393 pcs = (unsigned char *)pws;
394 pcd = (unsigned char *)pwd;
395
396 byte_copy:
397 while (len) {
398 /* *pcd++ = *pcs++; */
399 ldbma(s_space, pcs, t3, pmc_load_exc);
400 stbma(d_space, t3, pcd, pmc_store_exc);
401 len--;
402 }
403
404 return 0;
405
406 unaligned_copy:
407 /* possibly we are aligned on a word, but not on a double... */
408 if (likely(t1 & (sizeof(unsigned int)-1)) == 0) {
409 t2 = src & (sizeof(unsigned int) - 1);
410
411 if (unlikely(t2 != 0)) {
412 t2 = sizeof(unsigned int) - t2;
413 while (t2) {
414 /* *pcd++ = *pcs++; */
415 ldbma(s_space, pcs, t3, pmc_load_exc);
416 stbma(d_space, t3, pcd, pmc_store_exc);
417 len--;
418 t2--;
419 }
420 }
421
422 pws = (unsigned int *)pcs;
423 pwd = (unsigned int *)pcd;
424 goto word_copy;
425 }
426
427 /* Align the destination. */
428 if (unlikely((dst & (sizeof(unsigned int) - 1)) != 0)) {
429 t2 = sizeof(unsigned int) - (dst & (sizeof(unsigned int) - 1));
430 while (t2) {
431 /* *pcd++ = *pcs++; */
432 ldbma(s_space, pcs, t3, pmc_load_exc);
433 stbma(d_space, t3, pcd, pmc_store_exc);
434 len--;
435 t2--;
436 }
437 dst = (unsigned long)pcd;
438 src = (unsigned long)pcs;
439 }
440
441 ret = copy_dstaligned(dst, src, len / sizeof(unsigned int),
442 o_dst, o_src, o_len);
443 if (ret)
444 return ret;
445
446 pcs += (len & -sizeof(unsigned int));
447 pcd += (len & -sizeof(unsigned int));
448 len %= sizeof(unsigned int);
449
450 preserve_branch(handle_load_error);
451 preserve_branch(handle_store_error);
452
453 goto byte_copy;
454
455 handle_load_error:
456 __asm__ __volatile__ ("pmc_load_exc:\n");
457 d = &__get_cpu_var(exception_data);
458 DPRINTF("pmc_load_exc: o_len=%lu fault_addr=%lu o_src=%lu ret=%lu\n",
459 o_len, d->fault_addr, o_src, o_len - d->fault_addr + o_src);
460 return o_len - d->fault_addr + o_src;
461
462 handle_store_error:
463 __asm__ __volatile__ ("pmc_store_exc:\n");
464 d = &__get_cpu_var(exception_data);
465 DPRINTF("pmc_store_exc: o_len=%lu fault_addr=%lu o_dst=%lu ret=%lu\n",
466 o_len, d->fault_addr, o_dst, o_len - d->fault_addr + o_dst);
467 return o_len - d->fault_addr + o_dst;
468 }
469
470 #ifdef __KERNEL__
copy_to_user(void __user * dst,const void * src,unsigned long len)471 unsigned long copy_to_user(void __user *dst, const void *src, unsigned long len)
472 {
473 mtsp(get_kernel_space(), 1);
474 mtsp(get_user_space(), 2);
475 return pa_memcpy((void __force *)dst, src, len);
476 }
477
copy_from_user(void * dst,const void __user * src,unsigned long len)478 unsigned long copy_from_user(void *dst, const void __user *src, unsigned long len)
479 {
480 mtsp(get_user_space(), 1);
481 mtsp(get_kernel_space(), 2);
482 return pa_memcpy(dst, (void __force *)src, len);
483 }
484
copy_in_user(void __user * dst,const void __user * src,unsigned long len)485 unsigned long copy_in_user(void __user *dst, const void __user *src, unsigned long len)
486 {
487 mtsp(get_user_space(), 1);
488 mtsp(get_user_space(), 2);
489 return pa_memcpy((void __force *)dst, (void __force *)src, len);
490 }
491
492
memcpy(void * dst,const void * src,size_t count)493 void * memcpy(void * dst,const void *src, size_t count)
494 {
495 mtsp(get_kernel_space(), 1);
496 mtsp(get_kernel_space(), 2);
497 pa_memcpy(dst, src, count);
498 return dst;
499 }
500
501 EXPORT_SYMBOL(copy_to_user);
502 EXPORT_SYMBOL(copy_from_user);
503 EXPORT_SYMBOL(copy_in_user);
504 EXPORT_SYMBOL(memcpy);
505 #endif
506