2 * Itanium 2-optimized version of memcpy and copy_user function
5 * in0: destination address
7 * in2: number of bytes to copy
9 * for memcpy: return dest
10 * for copy_user: return 0 if success,
11 * or number of byte NOT copied if error occurred.
13 * Copyright (C) 2002 Intel Corp.
14 * Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
16 #include <asm/asmmacro.h>
18 #include <asm/export.h>
20 #define EK(y...) EX(y)
22 /* McKinley specific optimization */
38 /* r19-r30 are temp for each code section */
39 #define PREFETCH_DIST 8
40 #define src_pre_mem r19
41 #define dst_pre_mem r20
42 #define src_pre_l2 r21
43 #define dst_pre_l2 r22
48 #define t5 t1 // alias!
49 #define t6 t2 // alias!
50 #define t7 t3 // alias!
52 #define t9 t5 // alias!
53 #define t10 t4 // alias!
54 #define t11 t7 // alias!
55 #define t12 t6 // alias!
56 #define t14 t10 // alias!
61 /* defines for long_copy block */
63 #define B (PREFETCH_DIST)
64 #define C (B + PREFETCH_DIST)
67 #define Nrot ((N + 7) & ~7)
79 br.cond.sptk .common_code
83 GLOBAL_ENTRY(__copy_user)
85 // check dest alignment
89 mov saved_in0=in0 // save dest pointer
90 mov saved_in1=in1 // save src pointer
91 mov retval=r0 // initialize return value
94 cmp.gt p15,p0=8,in2 // check for small size
95 cmp.ne p13,p0=0,r28 // check dest alignment
96 cmp.ne p14,p0=0,r29 // check src alignment
98 sub r30=8,r28 // for .align_dest
99 mov saved_in2=in2 // save len
102 add dst1=1,in0 // dest odd index
103 cmp.le p6,p0 = 1,r30 // for .align_dest
104 (p15) br.cond.dpnt .memcpy_short
105 (p13) br.cond.dpnt .align_dest
106 (p14) br.cond.dpnt .unaligned_src
109 // both dest and src are aligned on 8-byte boundary
111 .save ar.pfs, saved_pfs
112 alloc saved_pfs=ar.pfs,3,Nrot-3,0,Nrot
116 shr.u cnt=in2,7 // this much cache line
118 cmp.lt p6,p0=2*PREFETCH_DIST,cnt
120 .save ar.lc, saved_lc
124 add src_pre_mem=0,in1 // prefetch src pointer
125 add dst_pre_mem=0,in0 // prefetch dest pointer
127 (p7) mov ar.lc=cnt // prefetch count
129 (p6) br.cond.dpnt .long_copy
133 lfetch.fault [src_pre_mem], 128
134 lfetch.fault.excl [dst_pre_mem], 128
135 br.cloop.dptk.few .prefetch
139 and tmp=31,in2 // copy length after iteration
140 shr.u r29=in2,5 // number of 32-byte iteration
141 add dst1=8,dst0 // 2nd dest pointer
143 add cnt=-1,r29 // ctop iteration adjustment
144 cmp.eq p10,p0=r29,r0 // do we really need to loop?
145 add src1=8,src0 // 2nd src pointer
149 mov ar.lc=cnt // loop setup
150 cmp.eq p16,p17 = r0,r0
152 (p10) br.dpnt.few .aligned_src_tail
156 EX(.ex_handler, (p16) ld8 r34=[src0],16)
157 EK(.ex_handler, (p16) ld8 r38=[src1],16)
158 EX(.ex_handler, (p17) st8 [dst0]=r33,16)
159 EK(.ex_handler, (p17) st8 [dst1]=r37,16)
161 EX(.ex_handler, (p16) ld8 r32=[src0],16)
162 EK(.ex_handler, (p16) ld8 r36=[src1],16)
163 EX(.ex_handler, (p16) st8 [dst0]=r34,16)
164 EK(.ex_handler, (p16) st8 [dst1]=r38,16)
169 EX(.ex_handler, (p6) ld8 t1=[src0])
172 EX(.ex_hndlr_s, (p7) ld8 t2=[src1],8)
176 EX(.ex_hndlr_s, (p8) ld8 t3=[src1])
177 EX(.ex_handler, (p6) st8 [dst0]=t1) // store byte 1
178 and in2=7,tmp // remaining length
179 EX(.ex_hndlr_d, (p7) st8 [dst1]=t2,8) // store byte 2
180 add src0=src0,r21 // setting up src pointer
181 add dst0=dst0,r21 // setting up dest pointer
183 EX(.ex_handler, (p8) st8 [dst1]=t3) // store byte 3
185 br.dptk.many .memcpy_short
188 /* code taken from copy_page_mck */
190 .rotr v[2*PREFETCH_DIST]
193 mov src_pre_mem = src0
195 mov ar.ec = 1 // special unrolled loop
197 mov dst_pre_mem = dst0
199 add src_pre_l2 = 8*8, src0
200 add dst_pre_l2 = 8*8, dst0
202 add src0 = 8, src_pre_mem // first t1 src
203 mov ar.lc = 2*PREFETCH_DIST - 1
204 shr.u cnt=in2,7 // number of lines
205 add src1 = 3*8, src_pre_mem // first t3 src
206 add dst0 = 8, dst_pre_mem // first t1 dst
207 add dst1 = 3*8, dst_pre_mem // first t3 dst
209 and tmp=127,in2 // remaining bytes after this block
210 add cnt = -(2*PREFETCH_DIST) - 1, cnt
211 // same as .line_copy loop, but with all predicated-off instructions removed:
213 EX(.ex_hndlr_lcpy_1, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0
214 EK(.ex_hndlr_lcpy_1, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2
215 br.ctop.sptk .prefetch_loop
217 cmp.eq p16, p0 = r0, r0 // reset p16 to 1
219 mov ar.ec = N // # of stages in pipeline
222 EX(.ex_handler, (p[D]) ld8 t2 = [src0], 3*8) // M0
223 EK(.ex_handler, (p[D]) ld8 t4 = [src1], 3*8) // M1
224 EX(.ex_handler_lcpy, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2 prefetch dst from memory
225 EK(.ex_handler_lcpy, (p[D]) st8 [dst_pre_l2] = n8, 128) // M3 prefetch dst from L2
227 EX(.ex_handler_lcpy, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0 prefetch src from memory
228 EK(.ex_handler_lcpy, (p[C]) ld8 n8 = [src_pre_l2], 128) // M1 prefetch src from L2
229 EX(.ex_handler, (p[D]) st8 [dst0] = t1, 8) // M2
230 EK(.ex_handler, (p[D]) st8 [dst1] = t3, 8) // M3
232 EX(.ex_handler, (p[D]) ld8 t5 = [src0], 8)
233 EK(.ex_handler, (p[D]) ld8 t7 = [src1], 3*8)
234 EX(.ex_handler, (p[D]) st8 [dst0] = t2, 3*8)
235 EK(.ex_handler, (p[D]) st8 [dst1] = t4, 3*8)
237 EX(.ex_handler, (p[D]) ld8 t6 = [src0], 3*8)
238 EK(.ex_handler, (p[D]) ld8 t10 = [src1], 8)
239 EX(.ex_handler, (p[D]) st8 [dst0] = t5, 8)
240 EK(.ex_handler, (p[D]) st8 [dst1] = t7, 3*8)
242 EX(.ex_handler, (p[D]) ld8 t9 = [src0], 3*8)
243 EK(.ex_handler, (p[D]) ld8 t11 = [src1], 3*8)
244 EX(.ex_handler, (p[D]) st8 [dst0] = t6, 3*8)
245 EK(.ex_handler, (p[D]) st8 [dst1] = t10, 8)
247 EX(.ex_handler, (p[D]) ld8 t12 = [src0], 8)
248 EK(.ex_handler, (p[D]) ld8 t14 = [src1], 8)
249 EX(.ex_handler, (p[D]) st8 [dst0] = t9, 3*8)
250 EK(.ex_handler, (p[D]) st8 [dst1] = t11, 3*8)
252 EX(.ex_handler, (p[D]) ld8 t13 = [src0], 4*8)
253 EK(.ex_handler, (p[D]) ld8 t15 = [src1], 4*8)
254 EX(.ex_handler, (p[D]) st8 [dst0] = t12, 8)
255 EK(.ex_handler, (p[D]) st8 [dst1] = t14, 8)
257 EX(.ex_handler, (p[C]) ld8 t1 = [src0], 8)
258 EK(.ex_handler, (p[C]) ld8 t3 = [src1], 8)
259 EX(.ex_handler, (p[D]) st8 [dst0] = t13, 4*8)
260 EK(.ex_handler, (p[D]) st8 [dst1] = t15, 4*8)
261 br.ctop.sptk .line_copy
268 br.sptk.many .medium_copy
271 #define BLOCK_SIZE 128*32
272 #define blocksize r23
275 // dest is on 8-byte boundary, src is not. We need to do
276 // ld8-ld8, shrp, then st8. Max 8 byte copy per cycle.
279 .save ar.pfs, saved_pfs
280 alloc saved_pfs=ar.pfs,3,5,0,8
281 .save ar.lc, saved_lc
287 mov saved_in0=dst0 // need to save all input arguments
289 mov blocksize=BLOCK_SIZE
291 cmp.lt p6,p7=blocksize,in2
294 (p6) mov in2=blocksize
296 shr.u r21=in2,7 // this much cache line
297 shr.u r22=in2,4 // number of 16-byte iteration
298 and curlen=15,in2 // copy length after iteration
299 and r30=7,src0 // source alignment
305 add src_pre_mem=0,src0 // prefetch src pointer
306 add dst_pre_mem=0,dst0 // prefetch dest pointer
307 and src0=-8,src0 // 1st src pointer
312 1: lfetch.fault [src_pre_mem], 128
313 lfetch.fault.excl [dst_pre_mem], 128
317 shladd dst1=r22,3,dst0 // 2nd dest pointer
318 shladd src1=r22,3,src0 // 2nd src pointer
319 cmp.eq p8,p9=r22,r0 // do we really need to loop?
320 cmp.le p6,p7=8,curlen; // have at least 8 byte remaining?
321 add cnt=-1,r22 // ctop iteration adjustment
323 EX(.ex_handler, (p9) ld8 r33=[src0],8) // loop primer
324 EK(.ex_handler, (p9) ld8 r37=[src1],8)
325 (p8) br.dpnt.few .noloop
328 // The jump address is calculated based on src alignment. The COPYU
329 // macro below need to confine its size to power of two, so an entry
330 // can be caulated using shl instead of an expensive multiply. The
331 // size is then hard coded by the following #define to match the
332 // actual size. This make it somewhat tedious when COPYU macro gets
333 // changed and this need to be adjusted to match.
336 mov r29=ip // jmp_table thread
339 add r29=.jump_table - 1b - (.jmp1-.jump_table), r29
340 shl r28=r30, LOOP_SIZE // jmp_table thread
341 mov ar.ec=2 // loop setup
343 add r29=r29,r28 // jmp_table thread
346 mov b6=r29 // jmp_table thread
350 // for 8-15 byte case
351 // We will skip the loop, but need to replicate the side effect
352 // that the loop produces.
354 EX(.ex_handler, (p6) ld8 r37=[src1],8)
358 EX(.ex_handler, (p6) ld8 r27=[src1])
359 (p6) shr.u r28=r37,r25
367 /* check if we have more than blocksize to copy, if so go back */
368 cmp.gt p8,p0=saved_in2,blocksize
370 (p8) add dst0=saved_in0,blocksize
371 (p8) add src0=saved_in1,blocksize
372 (p8) sub in2=saved_in2,blocksize
373 (p8) br.dpnt .4k_block
376 /* we have up to 15 byte to copy in the tail.
377 * part of work is already done in the jump table code
378 * we are at the following state.
381 * xxxxxx xx <----- r21 has xxxxxxxx already
382 * -------- -------- --------
389 * -------- -------- --------
394 EX(.ex_handler, (p6) st8 [dst1]=r21,8) // more than 8 byte to copy
395 (p6) add curlen=-8,curlen // update length
400 mov in2=curlen // remaining length
401 mov dst0=dst1 // dest pointer
402 add src0=src1,r30 // forward by src alignment
405 // 7 byte or smaller.
408 cmp.le p10,p11 = 2,in2
409 cmp.le p12,p13 = 3,in2
410 cmp.le p14,p15 = 4,in2
411 add src1=1,src0 // second src pointer
412 add dst1=1,dst0 // second dest pointer
415 EX(.ex_handler_short, (p8) ld1 t1=[src0],2)
416 EK(.ex_handler_short, (p10) ld1 t2=[src1],2)
417 (p9) br.ret.dpnt rp // 0 byte copy
420 EX(.ex_handler_short, (p8) st1 [dst0]=t1,2)
421 EK(.ex_handler_short, (p10) st1 [dst1]=t2,2)
422 (p11) br.ret.dpnt rp // 1 byte copy
424 EX(.ex_handler_short, (p12) ld1 t3=[src0],2)
425 EK(.ex_handler_short, (p14) ld1 t4=[src1],2)
426 (p13) br.ret.dpnt rp // 2 byte copy
431 cmp.le p10,p11 = 7,in2
433 EX(.ex_handler_short, (p12) st1 [dst0]=t3,2)
434 EK(.ex_handler_short, (p14) st1 [dst1]=t4,2)
435 (p15) br.ret.dpnt rp // 3 byte copy
438 EX(.ex_handler_short, (p6) ld1 t5=[src0],2)
439 EK(.ex_handler_short, (p8) ld1 t6=[src1],2)
440 (p7) br.ret.dpnt rp // 4 byte copy
443 EX(.ex_handler_short, (p6) st1 [dst0]=t5,2)
444 EK(.ex_handler_short, (p8) st1 [dst1]=t6,2)
445 (p9) br.ret.dptk rp // 5 byte copy
447 EX(.ex_handler_short, (p10) ld1 t7=[src0],2)
448 (p11) br.ret.dptk rp // 6 byte copy
451 EX(.ex_handler_short, (p10) st1 [dst0]=t7,2)
452 br.ret.dptk rp // done all cases
455 /* Align dest to nearest 8-byte boundary. We know we have at
456 * least 7 bytes to copy, enough to crawl to 8-byte boundary.
457 * Actual number of byte to crawl depend on the dest alignment.
458 * 7 byte or less is taken care at .memcpy_short
460 * src0 - source even index
461 * src1 - source odd index
462 * dst0 - dest even index
463 * dst1 - dest odd index
464 * r30 - distance to 8-byte boundary
468 add src1=1,in1 // source odd index
469 cmp.le p7,p0 = 2,r30 // for .align_dest
470 cmp.le p8,p0 = 3,r30 // for .align_dest
471 EX(.ex_handler_short, (p6) ld1 t1=[src0],2)
472 cmp.le p9,p0 = 4,r30 // for .align_dest
473 cmp.le p10,p0 = 5,r30
475 EX(.ex_handler_short, (p7) ld1 t2=[src1],2)
476 EK(.ex_handler_short, (p8) ld1 t3=[src0],2)
477 cmp.le p11,p0 = 6,r30
478 EX(.ex_handler_short, (p6) st1 [dst0] = t1,2)
479 cmp.le p12,p0 = 7,r30
481 EX(.ex_handler_short, (p9) ld1 t4=[src1],2)
482 EK(.ex_handler_short, (p10) ld1 t5=[src0],2)
483 EX(.ex_handler_short, (p7) st1 [dst1] = t2,2)
484 EK(.ex_handler_short, (p8) st1 [dst0] = t3,2)
486 EX(.ex_handler_short, (p11) ld1 t6=[src1],2)
487 EK(.ex_handler_short, (p12) ld1 t7=[src0],2)
489 EX(.ex_handler_short, (p9) st1 [dst1] = t4,2)
490 EK(.ex_handler_short, (p10) st1 [dst0] = t5,2)
493 EX(.ex_handler_short, (p11) st1 [dst1] = t6,2)
494 EK(.ex_handler_short, (p12) st1 [dst0] = t7)
495 add dst0=in0,r30 // setup arguments
497 (p6) br.cond.dptk .aligned_src
498 (p7) br.cond.dpnt .unaligned_src
501 /* main loop body in jump table format */
502 #define COPYU(shift) \
504 EX(.ex_handler, (p16) ld8 r32=[src0],8); /* 1 */ \
505 EK(.ex_handler, (p16) ld8 r36=[src1],8); \
506 (p17) shrp r35=r33,r34,shift;; /* 1 */ \
507 EX(.ex_handler, (p6) ld8 r22=[src1]); /* common, prime for tail section */ \
509 (p16) shrp r38=r36,r37,shift; \
510 EX(.ex_handler, (p17) st8 [dst0]=r35,8); /* 1 */ \
511 EK(.ex_handler, (p17) st8 [dst1]=r39,8); \
512 br.ctop.dptk.few 1b;; \
513 (p7) add src1=-8,src1; /* back out for <8 byte case */ \
514 shrp r21=r22,r38,shift; /* speculative work */ \
515 br.sptk.few .unaligned_src_tail /* branch out of jump table */ \
519 COPYU(8) // unaligned cases
534 * Due to lack of local tag support in gcc 2.x assembler, it is not clear which
535 * instruction failed in the bundle. The exception algorithm is that we
536 * first figure out the faulting address, then detect if there is any
537 * progress made on the copy, if so, redo the copy from last known copied
538 * location up to the faulting address (exclusive). In the copy_from_user
539 * case, remaining byte in kernel buffer will be zeroed.
541 * Take copy_from_user as an example, in the code there are multiple loads
542 * in a bundle and those multiple loads could span over two pages, the
543 * faulting address is calculated as page_round_down(max(src0, src1)).
544 * This is based on knowledge that if we can access one byte in a page, we
545 * can access any byte in that page.
547 * predicate used in the exception handler:
549 * p10-p11: src faulting addr calculation
550 * p12-p13: dst faulting addr calculation
559 #define saved_retval loc0
560 #define saved_rtlink loc1
561 #define saved_pfs_stack loc2
574 cmp.gtu p10,p11=src_pre_mem,saved_in1
575 cmp.gtu p12,p13=dst_pre_mem,saved_in0
577 (p10) add src0=8,saved_in1
578 (p11) mov src0=saved_in1
579 (p12) add dst0=8,saved_in0
580 (p13) mov dst0=saved_in0
583 // in line_copy block, the preload addresses should always ahead
584 // of the other two src/dst pointers. Furthermore, src1/dst1 should
585 // always ahead of src0/dst0.
589 mov pr=saved_pr,-1 // first restore pr, lc, and pfs
593 .ex_handler_short: // fault occurred in these sections didn't change pr, lc, pfs
594 cmp.ltu p6,p7=saved_in0, saved_in1 // get the copy direction
595 cmp.ltu p10,p11=src0,src1
596 cmp.ltu p12,p13=dst0,dst1
597 fcmp.eq p8,p0=f6,f0 // is it memcpy?
600 (p11) mov src1 = src0 // pick the larger of the two
601 (p13) mov dst0 = dst1 // make dst0 the smaller one
602 (p13) mov dst1 = tmp // and dst1 the larger one
604 (p6) dep F = r0,dst1,0,PAGE_SHIFT // usr dst round down to page boundary
605 (p7) dep F = r0,src1,0,PAGE_SHIFT // usr src round down to page boundary
607 (p6) cmp.le p14,p0=dst0,saved_in0 // no progress has been made on store
608 (p7) cmp.le p14,p0=src0,saved_in1 // no progress has been made on load
610 (p8) ld1 tmp=[src1] // force an oops for memcpy call
611 (p8) st1 [dst1]=r0 // force an oops for memcpy call
612 (p14) br.ret.sptk.many rp
615 * The remaining byte to copy is calculated as:
617 * A = (faulting_addr - orig_src) -> len to faulting ld address
619 * (faulting_addr - orig_dst) -> len to faulting st address
620 * B = (cur_dst - orig_dst) -> len copied so far
621 * C = A - B -> len need to be copied
622 * D = orig_len - A -> len need to be left along
624 (p6) sub A = F, saved_in0
625 (p7) sub A = F, saved_in1
628 alloc saved_pfs_stack=ar.pfs,3,3,3,0
630 sub B = dst0, saved_in0 // how many byte copied so far
632 (p8) mov A = 0; // A shouldn't be negative, cap it
637 cmp.gt p8,p0=C,r0 // more than 1 byte?
640 mov saved_rtlink = b0
642 add out0=saved_in0, B
643 add out1=saved_in1, B
645 (p8) br.call.sptk.few b0=__copy_user // recursive call
648 add saved_retval=saved_retval,r8 // above might return non-zero value
651 mov retval=saved_retval
652 mov ar.pfs=saved_pfs_stack
656 /* end of McKinley specific optimization */
658 EXPORT_SYMBOL(__copy_user)