1/* 2 * Itanium 2-optimized version of memcpy and copy_user function 3 * 4 * Inputs: 5 * in0: destination address 6 * in1: source address 7 * in2: number of bytes to copy 8 * Output: 9 * for memcpy: return dest 10 * for copy_user: return 0 if success, 11 * or number of byte NOT copied if error occurred. 12 * 13 * Copyright (C) 2002 Intel Corp. 14 * Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com> 15 */ 16#include <asm/asmmacro.h> 17#include <asm/page.h> 18 19#define EK(y...) EX(y) 20 21/* McKinley specific optimization */ 22 23#define retval r8 24#define saved_pfs r31 25#define saved_lc r10 26#define saved_pr r11 27#define saved_in0 r14 28#define saved_in1 r15 29#define saved_in2 r16 30 31#define src0 r2 32#define src1 r3 33#define dst0 r17 34#define dst1 r18 35#define cnt r9 36 37/* r19-r30 are temp for each code section */ 38#define PREFETCH_DIST 8 39#define src_pre_mem r19 40#define dst_pre_mem r20 41#define src_pre_l2 r21 42#define dst_pre_l2 r22 43#define t1 r23 44#define t2 r24 45#define t3 r25 46#define t4 r26 47#define t5 t1 // alias! 48#define t6 t2 // alias! 49#define t7 t3 // alias! 50#define n8 r27 51#define t9 t5 // alias! 52#define t10 t4 // alias! 53#define t11 t7 // alias! 54#define t12 t6 // alias! 55#define t14 t10 // alias! 56#define t13 r28 57#define t15 r29 58#define tmp r30 59 60/* defines for long_copy block */ 61#define A 0 62#define B (PREFETCH_DIST) 63#define C (B + PREFETCH_DIST) 64#define D (C + 1) 65#define N (D + 1) 66#define Nrot ((N + 7) & ~7) 67 68/* alias */ 69#define in0 r32 70#define in1 r33 71#define in2 r34 72 73GLOBAL_ENTRY(memcpy) 74 and r28=0x7,in0 75 and r29=0x7,in1 76 mov f6=f0 77 mov retval=in0 78 br.cond.sptk .common_code 79 ;; 80END(memcpy) 81GLOBAL_ENTRY(__copy_user) 82 .prologue 83// check dest alignment 84 and r28=0x7,in0 85 and r29=0x7,in1 86 mov f6=f1 87 mov saved_in0=in0 // save dest pointer 88 mov saved_in1=in1 // save src pointer 89 mov retval=r0 // initialize return value 90 ;; 91.common_code: 92 cmp.gt p15,p0=8,in2 // check for small size 93 cmp.ne p13,p0=0,r28 // check dest alignment 94 cmp.ne p14,p0=0,r29 // check src alignment 95 add src0=0,in1 96 sub r30=8,r28 // for .align_dest 97 mov saved_in2=in2 // save len 98 ;; 99 add dst0=0,in0 100 add dst1=1,in0 // dest odd index 101 cmp.le p6,p0 = 1,r30 // for .align_dest 102(p15) br.cond.dpnt .memcpy_short 103(p13) br.cond.dpnt .align_dest 104(p14) br.cond.dpnt .unaligned_src 105 ;; 106 107// both dest and src are aligned on 8-byte boundary 108.aligned_src: 109 .save ar.pfs, saved_pfs 110 alloc saved_pfs=ar.pfs,3,Nrot-3,0,Nrot 111 .save pr, saved_pr 112 mov saved_pr=pr 113 114 shr.u cnt=in2,7 // this much cache line 115 ;; 116 cmp.lt p6,p0=2*PREFETCH_DIST,cnt 117 cmp.lt p7,p8=1,cnt 118 .save ar.lc, saved_lc 119 mov saved_lc=ar.lc 120 .body 121 add cnt=-1,cnt 122 add src_pre_mem=0,in1 // prefetch src pointer 123 add dst_pre_mem=0,in0 // prefetch dest pointer 124 ;; 125(p7) mov ar.lc=cnt // prefetch count 126(p8) mov ar.lc=r0 127(p6) br.cond.dpnt .long_copy 128 ;; 129 130.prefetch: 131 lfetch.fault [src_pre_mem], 128 132 lfetch.fault.excl [dst_pre_mem], 128 133 br.cloop.dptk.few .prefetch 134 ;; 135 136.medium_copy: 137 and tmp=31,in2 // copy length after iteration 138 shr.u r29=in2,5 // number of 32-byte iteration 139 add dst1=8,dst0 // 2nd dest pointer 140 ;; 141 add cnt=-1,r29 // ctop iteration adjustment 142 cmp.eq p10,p0=r29,r0 // do we really need to loop? 143 add src1=8,src0 // 2nd src pointer 144 cmp.le p6,p0=8,tmp 145 ;; 146 cmp.le p7,p0=16,tmp 147 mov ar.lc=cnt // loop setup 148 cmp.eq p16,p17 = r0,r0 149 mov ar.ec=2 150(p10) br.dpnt.few .aligned_src_tail 151 ;; 152 TEXT_ALIGN(32) 1531: 154EX(.ex_handler, (p16) ld8 r34=[src0],16) 155EK(.ex_handler, (p16) ld8 r38=[src1],16) 156EX(.ex_handler, (p17) st8 [dst0]=r33,16) 157EK(.ex_handler, (p17) st8 [dst1]=r37,16) 158 ;; 159EX(.ex_handler, (p16) ld8 r32=[src0],16) 160EK(.ex_handler, (p16) ld8 r36=[src1],16) 161EX(.ex_handler, (p16) st8 [dst0]=r34,16) 162EK(.ex_handler, (p16) st8 [dst1]=r38,16) 163 br.ctop.dptk.few 1b 164 ;; 165 166.aligned_src_tail: 167EX(.ex_handler, (p6) ld8 t1=[src0]) 168 mov ar.lc=saved_lc 169 mov ar.pfs=saved_pfs 170EX(.ex_hndlr_s, (p7) ld8 t2=[src1],8) 171 cmp.le p8,p0=24,tmp 172 and r21=-8,tmp 173 ;; 174EX(.ex_hndlr_s, (p8) ld8 t3=[src1]) 175EX(.ex_handler, (p6) st8 [dst0]=t1) // store byte 1 176 and in2=7,tmp // remaining length 177EX(.ex_hndlr_d, (p7) st8 [dst1]=t2,8) // store byte 2 178 add src0=src0,r21 // setting up src pointer 179 add dst0=dst0,r21 // setting up dest pointer 180 ;; 181EX(.ex_handler, (p8) st8 [dst1]=t3) // store byte 3 182 mov pr=saved_pr,-1 183 br.dptk.many .memcpy_short 184 ;; 185 186/* code taken from copy_page_mck */ 187.long_copy: 188 .rotr v[2*PREFETCH_DIST] 189 .rotp p[N] 190 191 mov src_pre_mem = src0 192 mov pr.rot = 0x10000 193 mov ar.ec = 1 // special unrolled loop 194 195 mov dst_pre_mem = dst0 196 197 add src_pre_l2 = 8*8, src0 198 add dst_pre_l2 = 8*8, dst0 199 ;; 200 add src0 = 8, src_pre_mem // first t1 src 201 mov ar.lc = 2*PREFETCH_DIST - 1 202 shr.u cnt=in2,7 // number of lines 203 add src1 = 3*8, src_pre_mem // first t3 src 204 add dst0 = 8, dst_pre_mem // first t1 dst 205 add dst1 = 3*8, dst_pre_mem // first t3 dst 206 ;; 207 and tmp=127,in2 // remaining bytes after this block 208 add cnt = -(2*PREFETCH_DIST) - 1, cnt 209 // same as .line_copy loop, but with all predicated-off instructions removed: 210.prefetch_loop: 211EX(.ex_hndlr_lcpy_1, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0 212EK(.ex_hndlr_lcpy_1, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2 213 br.ctop.sptk .prefetch_loop 214 ;; 215 cmp.eq p16, p0 = r0, r0 // reset p16 to 1 216 mov ar.lc = cnt 217 mov ar.ec = N // # of stages in pipeline 218 ;; 219.line_copy: 220EX(.ex_handler, (p[D]) ld8 t2 = [src0], 3*8) // M0 221EK(.ex_handler, (p[D]) ld8 t4 = [src1], 3*8) // M1 222EX(.ex_handler_lcpy, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2 prefetch dst from memory 223EK(.ex_handler_lcpy, (p[D]) st8 [dst_pre_l2] = n8, 128) // M3 prefetch dst from L2 224 ;; 225EX(.ex_handler_lcpy, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0 prefetch src from memory 226EK(.ex_handler_lcpy, (p[C]) ld8 n8 = [src_pre_l2], 128) // M1 prefetch src from L2 227EX(.ex_handler, (p[D]) st8 [dst0] = t1, 8) // M2 228EK(.ex_handler, (p[D]) st8 [dst1] = t3, 8) // M3 229 ;; 230EX(.ex_handler, (p[D]) ld8 t5 = [src0], 8) 231EK(.ex_handler, (p[D]) ld8 t7 = [src1], 3*8) 232EX(.ex_handler, (p[D]) st8 [dst0] = t2, 3*8) 233EK(.ex_handler, (p[D]) st8 [dst1] = t4, 3*8) 234 ;; 235EX(.ex_handler, (p[D]) ld8 t6 = [src0], 3*8) 236EK(.ex_handler, (p[D]) ld8 t10 = [src1], 8) 237EX(.ex_handler, (p[D]) st8 [dst0] = t5, 8) 238EK(.ex_handler, (p[D]) st8 [dst1] = t7, 3*8) 239 ;; 240EX(.ex_handler, (p[D]) ld8 t9 = [src0], 3*8) 241EK(.ex_handler, (p[D]) ld8 t11 = [src1], 3*8) 242EX(.ex_handler, (p[D]) st8 [dst0] = t6, 3*8) 243EK(.ex_handler, (p[D]) st8 [dst1] = t10, 8) 244 ;; 245EX(.ex_handler, (p[D]) ld8 t12 = [src0], 8) 246EK(.ex_handler, (p[D]) ld8 t14 = [src1], 8) 247EX(.ex_handler, (p[D]) st8 [dst0] = t9, 3*8) 248EK(.ex_handler, (p[D]) st8 [dst1] = t11, 3*8) 249 ;; 250EX(.ex_handler, (p[D]) ld8 t13 = [src0], 4*8) 251EK(.ex_handler, (p[D]) ld8 t15 = [src1], 4*8) 252EX(.ex_handler, (p[D]) st8 [dst0] = t12, 8) 253EK(.ex_handler, (p[D]) st8 [dst1] = t14, 8) 254 ;; 255EX(.ex_handler, (p[C]) ld8 t1 = [src0], 8) 256EK(.ex_handler, (p[C]) ld8 t3 = [src1], 8) 257EX(.ex_handler, (p[D]) st8 [dst0] = t13, 4*8) 258EK(.ex_handler, (p[D]) st8 [dst1] = t15, 4*8) 259 br.ctop.sptk .line_copy 260 ;; 261 262 add dst0=-8,dst0 263 add src0=-8,src0 264 mov in2=tmp 265 .restore sp 266 br.sptk.many .medium_copy 267 ;; 268 269#define BLOCK_SIZE 128*32 270#define blocksize r23 271#define curlen r24 272 273// dest is on 8-byte boundary, src is not. We need to do 274// ld8-ld8, shrp, then st8. Max 8 byte copy per cycle. 275.unaligned_src: 276 .prologue 277 .save ar.pfs, saved_pfs 278 alloc saved_pfs=ar.pfs,3,5,0,8 279 .save ar.lc, saved_lc 280 mov saved_lc=ar.lc 281 .save pr, saved_pr 282 mov saved_pr=pr 283 .body 284.4k_block: 285 mov saved_in0=dst0 // need to save all input arguments 286 mov saved_in2=in2 287 mov blocksize=BLOCK_SIZE 288 ;; 289 cmp.lt p6,p7=blocksize,in2 290 mov saved_in1=src0 291 ;; 292(p6) mov in2=blocksize 293 ;; 294 shr.u r21=in2,7 // this much cache line 295 shr.u r22=in2,4 // number of 16-byte iteration 296 and curlen=15,in2 // copy length after iteration 297 and r30=7,src0 // source alignment 298 ;; 299 cmp.lt p7,p8=1,r21 300 add cnt=-1,r21 301 ;; 302 303 add src_pre_mem=0,src0 // prefetch src pointer 304 add dst_pre_mem=0,dst0 // prefetch dest pointer 305 and src0=-8,src0 // 1st src pointer 306(p7) mov ar.lc = cnt 307(p8) mov ar.lc = r0 308 ;; 309 TEXT_ALIGN(32) 3101: lfetch.fault [src_pre_mem], 128 311 lfetch.fault.excl [dst_pre_mem], 128 312 br.cloop.dptk.few 1b 313 ;; 314 315 shladd dst1=r22,3,dst0 // 2nd dest pointer 316 shladd src1=r22,3,src0 // 2nd src pointer 317 cmp.eq p8,p9=r22,r0 // do we really need to loop? 318 cmp.le p6,p7=8,curlen; // have at least 8 byte remaining? 319 add cnt=-1,r22 // ctop iteration adjustment 320 ;; 321EX(.ex_handler, (p9) ld8 r33=[src0],8) // loop primer 322EK(.ex_handler, (p9) ld8 r37=[src1],8) 323(p8) br.dpnt.few .noloop 324 ;; 325 326// The jump address is calculated based on src alignment. The COPYU 327// macro below need to confine its size to power of two, so an entry 328// can be caulated using shl instead of an expensive multiply. The 329// size is then hard coded by the following #define to match the 330// actual size. This make it somewhat tedious when COPYU macro gets 331// changed and this need to be adjusted to match. 332#define LOOP_SIZE 6 3331: 334 mov r29=ip // jmp_table thread 335 mov ar.lc=cnt 336 ;; 337 add r29=.jump_table - 1b - (.jmp1-.jump_table), r29 338 shl r28=r30, LOOP_SIZE // jmp_table thread 339 mov ar.ec=2 // loop setup 340 ;; 341 add r29=r29,r28 // jmp_table thread 342 cmp.eq p16,p17=r0,r0 343 ;; 344 mov b6=r29 // jmp_table thread 345 ;; 346 br.cond.sptk.few b6 347 348// for 8-15 byte case 349// We will skip the loop, but need to replicate the side effect 350// that the loop produces. 351.noloop: 352EX(.ex_handler, (p6) ld8 r37=[src1],8) 353 add src0=8,src0 354(p6) shl r25=r30,3 355 ;; 356EX(.ex_handler, (p6) ld8 r27=[src1]) 357(p6) shr.u r28=r37,r25 358(p6) sub r26=64,r25 359 ;; 360(p6) shl r27=r27,r26 361 ;; 362(p6) or r21=r28,r27 363 364.unaligned_src_tail: 365/* check if we have more than blocksize to copy, if so go back */ 366 cmp.gt p8,p0=saved_in2,blocksize 367 ;; 368(p8) add dst0=saved_in0,blocksize 369(p8) add src0=saved_in1,blocksize 370(p8) sub in2=saved_in2,blocksize 371(p8) br.dpnt .4k_block 372 ;; 373 374/* we have up to 15 byte to copy in the tail. 375 * part of work is already done in the jump table code 376 * we are at the following state. 377 * src side: 378 * 379 * xxxxxx xx <----- r21 has xxxxxxxx already 380 * -------- -------- -------- 381 * 0 8 16 382 * ^ 383 * | 384 * src1 385 * 386 * dst 387 * -------- -------- -------- 388 * ^ 389 * | 390 * dst1 391 */ 392EX(.ex_handler, (p6) st8 [dst1]=r21,8) // more than 8 byte to copy 393(p6) add curlen=-8,curlen // update length 394 mov ar.pfs=saved_pfs 395 ;; 396 mov ar.lc=saved_lc 397 mov pr=saved_pr,-1 398 mov in2=curlen // remaining length 399 mov dst0=dst1 // dest pointer 400 add src0=src1,r30 // forward by src alignment 401 ;; 402 403// 7 byte or smaller. 404.memcpy_short: 405 cmp.le p8,p9 = 1,in2 406 cmp.le p10,p11 = 2,in2 407 cmp.le p12,p13 = 3,in2 408 cmp.le p14,p15 = 4,in2 409 add src1=1,src0 // second src pointer 410 add dst1=1,dst0 // second dest pointer 411 ;; 412 413EX(.ex_handler_short, (p8) ld1 t1=[src0],2) 414EK(.ex_handler_short, (p10) ld1 t2=[src1],2) 415(p9) br.ret.dpnt rp // 0 byte copy 416 ;; 417 418EX(.ex_handler_short, (p8) st1 [dst0]=t1,2) 419EK(.ex_handler_short, (p10) st1 [dst1]=t2,2) 420(p11) br.ret.dpnt rp // 1 byte copy 421 422EX(.ex_handler_short, (p12) ld1 t3=[src0],2) 423EK(.ex_handler_short, (p14) ld1 t4=[src1],2) 424(p13) br.ret.dpnt rp // 2 byte copy 425 ;; 426 427 cmp.le p6,p7 = 5,in2 428 cmp.le p8,p9 = 6,in2 429 cmp.le p10,p11 = 7,in2 430 431EX(.ex_handler_short, (p12) st1 [dst0]=t3,2) 432EK(.ex_handler_short, (p14) st1 [dst1]=t4,2) 433(p15) br.ret.dpnt rp // 3 byte copy 434 ;; 435 436EX(.ex_handler_short, (p6) ld1 t5=[src0],2) 437EK(.ex_handler_short, (p8) ld1 t6=[src1],2) 438(p7) br.ret.dpnt rp // 4 byte copy 439 ;; 440 441EX(.ex_handler_short, (p6) st1 [dst0]=t5,2) 442EK(.ex_handler_short, (p8) st1 [dst1]=t6,2) 443(p9) br.ret.dptk rp // 5 byte copy 444 445EX(.ex_handler_short, (p10) ld1 t7=[src0],2) 446(p11) br.ret.dptk rp // 6 byte copy 447 ;; 448 449EX(.ex_handler_short, (p10) st1 [dst0]=t7,2) 450 br.ret.dptk rp // done all cases 451 452 453/* Align dest to nearest 8-byte boundary. We know we have at 454 * least 7 bytes to copy, enough to crawl to 8-byte boundary. 455 * Actual number of byte to crawl depend on the dest alignment. 456 * 7 byte or less is taken care at .memcpy_short 457 458 * src0 - source even index 459 * src1 - source odd index 460 * dst0 - dest even index 461 * dst1 - dest odd index 462 * r30 - distance to 8-byte boundary 463 */ 464 465.align_dest: 466 add src1=1,in1 // source odd index 467 cmp.le p7,p0 = 2,r30 // for .align_dest 468 cmp.le p8,p0 = 3,r30 // for .align_dest 469EX(.ex_handler_short, (p6) ld1 t1=[src0],2) 470 cmp.le p9,p0 = 4,r30 // for .align_dest 471 cmp.le p10,p0 = 5,r30 472 ;; 473EX(.ex_handler_short, (p7) ld1 t2=[src1],2) 474EK(.ex_handler_short, (p8) ld1 t3=[src0],2) 475 cmp.le p11,p0 = 6,r30 476EX(.ex_handler_short, (p6) st1 [dst0] = t1,2) 477 cmp.le p12,p0 = 7,r30 478 ;; 479EX(.ex_handler_short, (p9) ld1 t4=[src1],2) 480EK(.ex_handler_short, (p10) ld1 t5=[src0],2) 481EX(.ex_handler_short, (p7) st1 [dst1] = t2,2) 482EK(.ex_handler_short, (p8) st1 [dst0] = t3,2) 483 ;; 484EX(.ex_handler_short, (p11) ld1 t6=[src1],2) 485EK(.ex_handler_short, (p12) ld1 t7=[src0],2) 486 cmp.eq p6,p7=r28,r29 487EX(.ex_handler_short, (p9) st1 [dst1] = t4,2) 488EK(.ex_handler_short, (p10) st1 [dst0] = t5,2) 489 sub in2=in2,r30 490 ;; 491EX(.ex_handler_short, (p11) st1 [dst1] = t6,2) 492EK(.ex_handler_short, (p12) st1 [dst0] = t7) 493 add dst0=in0,r30 // setup arguments 494 add src0=in1,r30 495(p6) br.cond.dptk .aligned_src 496(p7) br.cond.dpnt .unaligned_src 497 ;; 498 499/* main loop body in jump table format */ 500#define COPYU(shift) \ 5011: \ 502EX(.ex_handler, (p16) ld8 r32=[src0],8); /* 1 */ \ 503EK(.ex_handler, (p16) ld8 r36=[src1],8); \ 504 (p17) shrp r35=r33,r34,shift;; /* 1 */ \ 505EX(.ex_handler, (p6) ld8 r22=[src1]); /* common, prime for tail section */ \ 506 nop.m 0; \ 507 (p16) shrp r38=r36,r37,shift; \ 508EX(.ex_handler, (p17) st8 [dst0]=r35,8); /* 1 */ \ 509EK(.ex_handler, (p17) st8 [dst1]=r39,8); \ 510 br.ctop.dptk.few 1b;; \ 511 (p7) add src1=-8,src1; /* back out for <8 byte case */ \ 512 shrp r21=r22,r38,shift; /* speculative work */ \ 513 br.sptk.few .unaligned_src_tail /* branch out of jump table */ \ 514 ;; 515 TEXT_ALIGN(32) 516.jump_table: 517 COPYU(8) // unaligned cases 518.jmp1: 519 COPYU(16) 520 COPYU(24) 521 COPYU(32) 522 COPYU(40) 523 COPYU(48) 524 COPYU(56) 525 526#undef A 527#undef B 528#undef C 529#undef D 530 531/* 532 * Due to lack of local tag support in gcc 2.x assembler, it is not clear which 533 * instruction failed in the bundle. The exception algorithm is that we 534 * first figure out the faulting address, then detect if there is any 535 * progress made on the copy, if so, redo the copy from last known copied 536 * location up to the faulting address (exclusive). In the copy_from_user 537 * case, remaining byte in kernel buffer will be zeroed. 538 * 539 * Take copy_from_user as an example, in the code there are multiple loads 540 * in a bundle and those multiple loads could span over two pages, the 541 * faulting address is calculated as page_round_down(max(src0, src1)). 542 * This is based on knowledge that if we can access one byte in a page, we 543 * can access any byte in that page. 544 * 545 * predicate used in the exception handler: 546 * p6-p7: direction 547 * p10-p11: src faulting addr calculation 548 * p12-p13: dst faulting addr calculation 549 */ 550 551#define A r19 552#define B r20 553#define C r21 554#define D r22 555#define F r28 556 557#define memset_arg0 r32 558#define memset_arg2 r33 559 560#define saved_retval loc0 561#define saved_rtlink loc1 562#define saved_pfs_stack loc2 563 564.ex_hndlr_s: 565 add src0=8,src0 566 br.sptk .ex_handler 567 ;; 568.ex_hndlr_d: 569 add dst0=8,dst0 570 br.sptk .ex_handler 571 ;; 572.ex_hndlr_lcpy_1: 573 mov src1=src_pre_mem 574 mov dst1=dst_pre_mem 575 cmp.gtu p10,p11=src_pre_mem,saved_in1 576 cmp.gtu p12,p13=dst_pre_mem,saved_in0 577 ;; 578(p10) add src0=8,saved_in1 579(p11) mov src0=saved_in1 580(p12) add dst0=8,saved_in0 581(p13) mov dst0=saved_in0 582 br.sptk .ex_handler 583.ex_handler_lcpy: 584 // in line_copy block, the preload addresses should always ahead 585 // of the other two src/dst pointers. Furthermore, src1/dst1 should 586 // always ahead of src0/dst0. 587 mov src1=src_pre_mem 588 mov dst1=dst_pre_mem 589.ex_handler: 590 mov pr=saved_pr,-1 // first restore pr, lc, and pfs 591 mov ar.lc=saved_lc 592 mov ar.pfs=saved_pfs 593 ;; 594.ex_handler_short: // fault occurred in these sections didn't change pr, lc, pfs 595 cmp.ltu p6,p7=saved_in0, saved_in1 // get the copy direction 596 cmp.ltu p10,p11=src0,src1 597 cmp.ltu p12,p13=dst0,dst1 598 fcmp.eq p8,p0=f6,f0 // is it memcpy? 599 mov tmp = dst0 600 ;; 601(p11) mov src1 = src0 // pick the larger of the two 602(p13) mov dst0 = dst1 // make dst0 the smaller one 603(p13) mov dst1 = tmp // and dst1 the larger one 604 ;; 605(p6) dep F = r0,dst1,0,PAGE_SHIFT // usr dst round down to page boundary 606(p7) dep F = r0,src1,0,PAGE_SHIFT // usr src round down to page boundary 607 ;; 608(p6) cmp.le p14,p0=dst0,saved_in0 // no progress has been made on store 609(p7) cmp.le p14,p0=src0,saved_in1 // no progress has been made on load 610 mov retval=saved_in2 611(p8) ld1 tmp=[src1] // force an oops for memcpy call 612(p8) st1 [dst1]=r0 // force an oops for memcpy call 613(p14) br.ret.sptk.many rp 614 615/* 616 * The remaining byte to copy is calculated as: 617 * 618 * A = (faulting_addr - orig_src) -> len to faulting ld address 619 * or 620 * (faulting_addr - orig_dst) -> len to faulting st address 621 * B = (cur_dst - orig_dst) -> len copied so far 622 * C = A - B -> len need to be copied 623 * D = orig_len - A -> len need to be zeroed 624 */ 625(p6) sub A = F, saved_in0 626(p7) sub A = F, saved_in1 627 clrrrb 628 ;; 629 alloc saved_pfs_stack=ar.pfs,3,3,3,0 630 cmp.lt p8,p0=A,r0 631 sub B = dst0, saved_in0 // how many byte copied so far 632 ;; 633(p8) mov A = 0; // A shouldn't be negative, cap it 634 ;; 635 sub C = A, B 636 sub D = saved_in2, A 637 ;; 638 cmp.gt p8,p0=C,r0 // more than 1 byte? 639 add memset_arg0=saved_in0, A 640(p6) mov memset_arg2=0 // copy_to_user should not call memset 641(p7) mov memset_arg2=D // copy_from_user need to have kbuf zeroed 642 mov r8=0 643 mov saved_retval = D 644 mov saved_rtlink = b0 645 646 add out0=saved_in0, B 647 add out1=saved_in1, B 648 mov out2=C 649(p8) br.call.sptk.few b0=__copy_user // recursive call 650 ;; 651 652 add saved_retval=saved_retval,r8 // above might return non-zero value 653 cmp.gt p8,p0=memset_arg2,r0 // more than 1 byte? 654 mov out0=memset_arg0 // *s 655 mov out1=r0 // c 656 mov out2=memset_arg2 // n 657(p8) br.call.sptk.few b0=memset 658 ;; 659 660 mov retval=saved_retval 661 mov ar.pfs=saved_pfs_stack 662 mov b0=saved_rtlink 663 br.ret.sptk.many rp 664 665/* end of McKinley specific optimization */ 666END(__copy_user) 667