LXR linux/arch/ia64/lib/memcpy

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Itanium 2-optimized version of memcpy and copy_user function
   4 *
   5 * Inputs:
   6 *      in0:    destination address
   7 *      in1:    source address
   8 *      in2:    number of bytes to copy
   9 * Output:
  10 *      for memcpy:    return dest
  11 *      for copy_user: return 0 if success,
  12 *                     or number of byte NOT copied if error occurred.
  13 *
  14 * Copyright (C) 2002 Intel Corp.
  15 * Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
  16 */
  17#include <asm/asmmacro.h>
  18#include <asm/page.h>
  19#include <asm/export.h>
  20
  21#define EK(y...) EX(y)
  22
  23/* McKinley specific optimization */
  24
  25#define retval          r8
  26#define saved_pfs       r31
  27#define saved_lc        r10
  28#define saved_pr        r11
  29#define saved_in0       r14
  30#define saved_in1       r15
  31#define saved_in2       r16
  32
  33#define src0            r2
  34#define src1            r3
  35#define dst0            r17
  36#define dst1            r18
  37#define cnt             r9
  38
  39/* r19-r30 are temp for each code section */
  40#define PREFETCH_DIST   8
  41#define src_pre_mem     r19
  42#define dst_pre_mem     r20
  43#define src_pre_l2      r21
  44#define dst_pre_l2      r22
  45#define t1              r23
  46#define t2              r24
  47#define t3              r25
  48#define t4              r26
  49#define t5              t1      // alias!
  50#define t6              t2      // alias!
  51#define t7              t3      // alias!
  52#define n8              r27
  53#define t9              t5      // alias!
  54#define t10             t4      // alias!
  55#define t11             t7      // alias!
  56#define t12             t6      // alias!
  57#define t14             t10     // alias!
  58#define t13             r28
  59#define t15             r29
  60#define tmp             r30
  61
  62/* defines for long_copy block */
  63#define A       0
  64#define B       (PREFETCH_DIST)
  65#define C       (B + PREFETCH_DIST)
  66#define D       (C + 1)
  67#define N       (D + 1)
  68#define Nrot    ((N + 7) & ~7)
  69
  70/* alias */
  71#define in0             r32
  72#define in1             r33
  73#define in2             r34
  74
  75GLOBAL_ENTRY(memcpy)
  76        and     r28=0x7,in0
  77        and     r29=0x7,in1
  78        mov     f6=f0
  79        mov     retval=in0
  80        br.cond.sptk .common_code
  81        ;;
  82END(memcpy)
  83EXPORT_SYMBOL(memcpy)
  84GLOBAL_ENTRY(__copy_user)
  85        .prologue
  86// check dest alignment
  87        and     r28=0x7,in0
  88        and     r29=0x7,in1
  89        mov     f6=f1
  90        mov     saved_in0=in0   // save dest pointer
  91        mov     saved_in1=in1   // save src pointer
  92        mov     retval=r0       // initialize return value
  93        ;;
  94.common_code:
  95        cmp.gt  p15,p0=8,in2    // check for small size
  96        cmp.ne  p13,p0=0,r28    // check dest alignment
  97        cmp.ne  p14,p0=0,r29    // check src alignment
  98        add     src0=0,in1
  99        sub     r30=8,r28       // for .align_dest
 100        mov     saved_in2=in2   // save len
 101        ;;
 102        add     dst0=0,in0
 103        add     dst1=1,in0      // dest odd index
 104        cmp.le  p6,p0 = 1,r30   // for .align_dest
 105(p15)   br.cond.dpnt .memcpy_short
 106(p13)   br.cond.dpnt .align_dest
 107(p14)   br.cond.dpnt .unaligned_src
 108        ;;
 109
 110// both dest and src are aligned on 8-byte boundary
 111.aligned_src:
 112        .save ar.pfs, saved_pfs
 113        alloc   saved_pfs=ar.pfs,3,Nrot-3,0,Nrot
 114        .save pr, saved_pr
 115        mov     saved_pr=pr
 116
 117        shr.u   cnt=in2,7       // this much cache line
 118        ;;
 119        cmp.lt  p6,p0=2*PREFETCH_DIST,cnt
 120        cmp.lt  p7,p8=1,cnt
 121        .save ar.lc, saved_lc
 122        mov     saved_lc=ar.lc
 123        .body
 124        add     cnt=-1,cnt
 125        add     src_pre_mem=0,in1       // prefetch src pointer
 126        add     dst_pre_mem=0,in0       // prefetch dest pointer
 127        ;;
 128(p7)    mov     ar.lc=cnt       // prefetch count
 129(p8)    mov     ar.lc=r0
 130(p6)    br.cond.dpnt .long_copy
 131        ;;
 132
 133.prefetch:
 134        lfetch.fault      [src_pre_mem], 128
 135        lfetch.fault.excl [dst_pre_mem], 128
 136        br.cloop.dptk.few .prefetch
 137        ;;
 138
 139.medium_copy:
 140        and     tmp=31,in2      // copy length after iteration
 141        shr.u   r29=in2,5       // number of 32-byte iteration
 142        add     dst1=8,dst0     // 2nd dest pointer
 143        ;;
 144        add     cnt=-1,r29      // ctop iteration adjustment
 145        cmp.eq  p10,p0=r29,r0   // do we really need to loop?
 146        add     src1=8,src0     // 2nd src pointer
 147        cmp.le  p6,p0=8,tmp
 148        ;;
 149        cmp.le  p7,p0=16,tmp
 150        mov     ar.lc=cnt       // loop setup
 151        cmp.eq  p16,p17 = r0,r0
 152        mov     ar.ec=2
 153(p10)   br.dpnt.few .aligned_src_tail
 154        ;;
 155        TEXT_ALIGN(32)
 1561:
 157EX(.ex_handler, (p16)   ld8     r34=[src0],16)
 158EK(.ex_handler, (p16)   ld8     r38=[src1],16)
 159EX(.ex_handler, (p17)   st8     [dst0]=r33,16)
 160EK(.ex_handler, (p17)   st8     [dst1]=r37,16)
 161        ;;
 162EX(.ex_handler, (p16)   ld8     r32=[src0],16)
 163EK(.ex_handler, (p16)   ld8     r36=[src1],16)
 164EX(.ex_handler, (p16)   st8     [dst0]=r34,16)
 165EK(.ex_handler, (p16)   st8     [dst1]=r38,16)
 166        br.ctop.dptk.few 1b
 167        ;;
 168
 169.aligned_src_tail:
 170EX(.ex_handler, (p6)    ld8     t1=[src0])
 171        mov     ar.lc=saved_lc
 172        mov     ar.pfs=saved_pfs
 173EX(.ex_hndlr_s, (p7)    ld8     t2=[src1],8)
 174        cmp.le  p8,p0=24,tmp
 175        and     r21=-8,tmp
 176        ;;
 177EX(.ex_hndlr_s, (p8)    ld8     t3=[src1])
 178EX(.ex_handler, (p6)    st8     [dst0]=t1)      // store byte 1
 179        and     in2=7,tmp       // remaining length
 180EX(.ex_hndlr_d, (p7)    st8     [dst1]=t2,8)    // store byte 2
 181        add     src0=src0,r21   // setting up src pointer
 182        add     dst0=dst0,r21   // setting up dest pointer
 183        ;;
 184EX(.ex_handler, (p8)    st8     [dst1]=t3)      // store byte 3
 185        mov     pr=saved_pr,-1
 186        br.dptk.many .memcpy_short
 187        ;;
 188
 189/* code taken from copy_page_mck */
 190.long_copy:
 191        .rotr v[2*PREFETCH_DIST]
 192        .rotp p[N]
 193
 194        mov src_pre_mem = src0
 195        mov pr.rot = 0x10000
 196        mov ar.ec = 1                           // special unrolled loop
 197
 198        mov dst_pre_mem = dst0
 199
 200        add src_pre_l2 = 8*8, src0
 201        add dst_pre_l2 = 8*8, dst0
 202        ;;
 203        add src0 = 8, src_pre_mem               // first t1 src
 204        mov ar.lc = 2*PREFETCH_DIST - 1
 205        shr.u cnt=in2,7                         // number of lines
 206        add src1 = 3*8, src_pre_mem             // first t3 src
 207        add dst0 = 8, dst_pre_mem               // first t1 dst
 208        add dst1 = 3*8, dst_pre_mem             // first t3 dst
 209        ;;
 210        and tmp=127,in2                         // remaining bytes after this block
 211        add cnt = -(2*PREFETCH_DIST) - 1, cnt
 212        // same as .line_copy loop, but with all predicated-off instructions removed:
 213.prefetch_loop:
 214EX(.ex_hndlr_lcpy_1, (p[A])     ld8 v[A] = [src_pre_mem], 128)          // M0
 215EK(.ex_hndlr_lcpy_1, (p[B])     st8 [dst_pre_mem] = v[B], 128)          // M2
 216        br.ctop.sptk .prefetch_loop
 217        ;;
 218        cmp.eq p16, p0 = r0, r0                 // reset p16 to 1
 219        mov ar.lc = cnt
 220        mov ar.ec = N                           // # of stages in pipeline
 221        ;;
 222.line_copy:
 223EX(.ex_handler, (p[D])  ld8 t2 = [src0], 3*8)                   // M0
 224EK(.ex_handler, (p[D])  ld8 t4 = [src1], 3*8)                   // M1
 225EX(.ex_handler_lcpy,    (p[B])  st8 [dst_pre_mem] = v[B], 128)          // M2 prefetch dst from memory
 226EK(.ex_handler_lcpy,    (p[D])  st8 [dst_pre_l2] = n8, 128)             // M3 prefetch dst from L2
 227        ;;
 228EX(.ex_handler_lcpy,    (p[A])  ld8 v[A] = [src_pre_mem], 128)          // M0 prefetch src from memory
 229EK(.ex_handler_lcpy,    (p[C])  ld8 n8 = [src_pre_l2], 128)             // M1 prefetch src from L2
 230EX(.ex_handler, (p[D])  st8 [dst0] =  t1, 8)                    // M2
 231EK(.ex_handler, (p[D])  st8 [dst1] =  t3, 8)                    // M3
 232        ;;
 233EX(.ex_handler, (p[D])  ld8  t5 = [src0], 8)
 234EK(.ex_handler, (p[D])  ld8  t7 = [src1], 3*8)
 235EX(.ex_handler, (p[D])  st8 [dst0] =  t2, 3*8)
 236EK(.ex_handler, (p[D])  st8 [dst1] =  t4, 3*8)
 237        ;;
 238EX(.ex_handler, (p[D])  ld8  t6 = [src0], 3*8)
 239EK(.ex_handler, (p[D])  ld8 t10 = [src1], 8)
 240EX(.ex_handler, (p[D])  st8 [dst0] =  t5, 8)
 241EK(.ex_handler, (p[D])  st8 [dst1] =  t7, 3*8)
 242        ;;
 243EX(.ex_handler, (p[D])  ld8  t9 = [src0], 3*8)
 244EK(.ex_handler, (p[D])  ld8 t11 = [src1], 3*8)
 245EX(.ex_handler, (p[D])  st8 [dst0] =  t6, 3*8)
 246EK(.ex_handler, (p[D])  st8 [dst1] = t10, 8)
 247        ;;
 248EX(.ex_handler, (p[D])  ld8 t12 = [src0], 8)
 249EK(.ex_handler, (p[D])  ld8 t14 = [src1], 8)
 250EX(.ex_handler, (p[D])  st8 [dst0] =  t9, 3*8)
 251EK(.ex_handler, (p[D])  st8 [dst1] = t11, 3*8)
 252        ;;
 253EX(.ex_handler, (p[D])  ld8 t13 = [src0], 4*8)
 254EK(.ex_handler, (p[D])  ld8 t15 = [src1], 4*8)
 255EX(.ex_handler, (p[D])  st8 [dst0] = t12, 8)
 256EK(.ex_handler, (p[D])  st8 [dst1] = t14, 8)
 257        ;;
 258EX(.ex_handler, (p[C])  ld8  t1 = [src0], 8)
 259EK(.ex_handler, (p[C])  ld8  t3 = [src1], 8)
 260EX(.ex_handler, (p[D])  st8 [dst0] = t13, 4*8)
 261EK(.ex_handler, (p[D])  st8 [dst1] = t15, 4*8)
 262        br.ctop.sptk .line_copy
 263        ;;
 264
 265        add dst0=-8,dst0
 266        add src0=-8,src0
 267        mov in2=tmp
 268        .restore sp
 269        br.sptk.many .medium_copy
 270        ;;
 271
 272#define BLOCK_SIZE      128*32
 273#define blocksize       r23
 274#define curlen          r24
 275
 276// dest is on 8-byte boundary, src is not. We need to do
 277// ld8-ld8, shrp, then st8.  Max 8 byte copy per cycle.
 278.unaligned_src:
 279        .prologue
 280        .save ar.pfs, saved_pfs
 281        alloc   saved_pfs=ar.pfs,3,5,0,8
 282        .save ar.lc, saved_lc
 283        mov     saved_lc=ar.lc
 284        .save pr, saved_pr
 285        mov     saved_pr=pr
 286        .body
 287.4k_block:
 288        mov     saved_in0=dst0  // need to save all input arguments
 289        mov     saved_in2=in2
 290        mov     blocksize=BLOCK_SIZE
 291        ;;
 292        cmp.lt  p6,p7=blocksize,in2
 293        mov     saved_in1=src0
 294        ;;
 295(p6)    mov     in2=blocksize
 296        ;;
 297        shr.u   r21=in2,7       // this much cache line
 298        shr.u   r22=in2,4       // number of 16-byte iteration
 299        and     curlen=15,in2   // copy length after iteration
 300        and     r30=7,src0      // source alignment
 301        ;;
 302        cmp.lt  p7,p8=1,r21
 303        add     cnt=-1,r21
 304        ;;
 305
 306        add     src_pre_mem=0,src0      // prefetch src pointer
 307        add     dst_pre_mem=0,dst0      // prefetch dest pointer
 308        and     src0=-8,src0            // 1st src pointer
 309(p7)    mov     ar.lc = cnt
 310(p8)    mov     ar.lc = r0
 311        ;;
 312        TEXT_ALIGN(32)
 3131:      lfetch.fault      [src_pre_mem], 128
 314        lfetch.fault.excl [dst_pre_mem], 128
 315        br.cloop.dptk.few 1b
 316        ;;
 317
 318        shladd  dst1=r22,3,dst0 // 2nd dest pointer
 319        shladd  src1=r22,3,src0 // 2nd src pointer
 320        cmp.eq  p8,p9=r22,r0    // do we really need to loop?
 321        cmp.le  p6,p7=8,curlen; // have at least 8 byte remaining?
 322        add     cnt=-1,r22      // ctop iteration adjustment
 323        ;;
 324EX(.ex_handler, (p9)    ld8     r33=[src0],8)   // loop primer
 325EK(.ex_handler, (p9)    ld8     r37=[src1],8)
 326(p8)    br.dpnt.few .noloop
 327        ;;
 328
 329// The jump address is calculated based on src alignment. The COPYU
 330// macro below need to confine its size to power of two, so an entry
 331// can be caulated using shl instead of an expensive multiply. The
 332// size is then hard coded by the following #define to match the
 333// actual size.  This make it somewhat tedious when COPYU macro gets
 334// changed and this need to be adjusted to match.
 335#define LOOP_SIZE 6
 3361:
 337        mov     r29=ip          // jmp_table thread
 338        mov     ar.lc=cnt
 339        ;;
 340        add     r29=.jump_table - 1b - (.jmp1-.jump_table), r29
 341        shl     r28=r30, LOOP_SIZE      // jmp_table thread
 342        mov     ar.ec=2         // loop setup
 343        ;;
 344        add     r29=r29,r28             // jmp_table thread
 345        cmp.eq  p16,p17=r0,r0
 346        ;;
 347        mov     b6=r29                  // jmp_table thread
 348        ;;
 349        br.cond.sptk.few b6
 350
 351// for 8-15 byte case
 352// We will skip the loop, but need to replicate the side effect
 353// that the loop produces.
 354.noloop:
 355EX(.ex_handler, (p6)    ld8     r37=[src1],8)
 356        add     src0=8,src0
 357(p6)    shl     r25=r30,3
 358        ;;
 359EX(.ex_handler, (p6)    ld8     r27=[src1])
 360(p6)    shr.u   r28=r37,r25
 361(p6)    sub     r26=64,r25
 362        ;;
 363(p6)    shl     r27=r27,r26
 364        ;;
 365(p6)    or      r21=r28,r27
 366
 367.unaligned_src_tail:
 368/* check if we have more than blocksize to copy, if so go back */
 369        cmp.gt  p8,p0=saved_in2,blocksize
 370        ;;
 371(p8)    add     dst0=saved_in0,blocksize
 372(p8)    add     src0=saved_in1,blocksize
 373(p8)    sub     in2=saved_in2,blocksize
 374(p8)    br.dpnt .4k_block
 375        ;;
 376
 377/* we have up to 15 byte to copy in the tail.
 378 * part of work is already done in the jump table code
 379 * we are at the following state.
 380 * src side:
 381 * 
 382 *   xxxxxx xx                   <----- r21 has xxxxxxxx already
 383 * -------- -------- --------
 384 * 0        8        16
 385 *          ^
 386 *          |
 387 *          src1
 388 * 
 389 * dst
 390 * -------- -------- --------
 391 * ^
 392 * |
 393 * dst1
 394 */
 395EX(.ex_handler, (p6)    st8     [dst1]=r21,8)   // more than 8 byte to copy
 396(p6)    add     curlen=-8,curlen        // update length
 397        mov     ar.pfs=saved_pfs
 398        ;;
 399        mov     ar.lc=saved_lc
 400        mov     pr=saved_pr,-1
 401        mov     in2=curlen      // remaining length
 402        mov     dst0=dst1       // dest pointer
 403        add     src0=src1,r30   // forward by src alignment
 404        ;;
 405
 406// 7 byte or smaller.
 407.memcpy_short:
 408        cmp.le  p8,p9   = 1,in2
 409        cmp.le  p10,p11 = 2,in2
 410        cmp.le  p12,p13 = 3,in2
 411        cmp.le  p14,p15 = 4,in2
 412        add     src1=1,src0     // second src pointer
 413        add     dst1=1,dst0     // second dest pointer
 414        ;;
 415
 416EX(.ex_handler_short, (p8)      ld1     t1=[src0],2)
 417EK(.ex_handler_short, (p10)     ld1     t2=[src1],2)
 418(p9)    br.ret.dpnt rp          // 0 byte copy
 419        ;;
 420
 421EX(.ex_handler_short, (p8)      st1     [dst0]=t1,2)
 422EK(.ex_handler_short, (p10)     st1     [dst1]=t2,2)
 423(p11)   br.ret.dpnt rp          // 1 byte copy
 424
 425EX(.ex_handler_short, (p12)     ld1     t3=[src0],2)
 426EK(.ex_handler_short, (p14)     ld1     t4=[src1],2)
 427(p13)   br.ret.dpnt rp          // 2 byte copy
 428        ;;
 429
 430        cmp.le  p6,p7   = 5,in2
 431        cmp.le  p8,p9   = 6,in2
 432        cmp.le  p10,p11 = 7,in2
 433
 434EX(.ex_handler_short, (p12)     st1     [dst0]=t3,2)
 435EK(.ex_handler_short, (p14)     st1     [dst1]=t4,2)
 436(p15)   br.ret.dpnt rp          // 3 byte copy
 437        ;;
 438
 439EX(.ex_handler_short, (p6)      ld1     t5=[src0],2)
 440EK(.ex_handler_short, (p8)      ld1     t6=[src1],2)
 441(p7)    br.ret.dpnt rp          // 4 byte copy
 442        ;;
 443
 444EX(.ex_handler_short, (p6)      st1     [dst0]=t5,2)
 445EK(.ex_handler_short, (p8)      st1     [dst1]=t6,2)
 446(p9)    br.ret.dptk rp          // 5 byte copy
 447
 448EX(.ex_handler_short, (p10)     ld1     t7=[src0],2)
 449(p11)   br.ret.dptk rp          // 6 byte copy
 450        ;;
 451
 452EX(.ex_handler_short, (p10)     st1     [dst0]=t7,2)
 453        br.ret.dptk rp          // done all cases
 454
 455
 456/* Align dest to nearest 8-byte boundary. We know we have at
 457 * least 7 bytes to copy, enough to crawl to 8-byte boundary.
 458 * Actual number of byte to crawl depend on the dest alignment.
 459 * 7 byte or less is taken care at .memcpy_short
 460
 461 * src0 - source even index
 462 * src1 - source  odd index
 463 * dst0 - dest even index
 464 * dst1 - dest  odd index
 465 * r30  - distance to 8-byte boundary
 466 */
 467
 468.align_dest:
 469        add     src1=1,in1      // source odd index
 470        cmp.le  p7,p0 = 2,r30   // for .align_dest
 471        cmp.le  p8,p0 = 3,r30   // for .align_dest
 472EX(.ex_handler_short, (p6)      ld1     t1=[src0],2)
 473        cmp.le  p9,p0 = 4,r30   // for .align_dest
 474        cmp.le  p10,p0 = 5,r30
 475        ;;
 476EX(.ex_handler_short, (p7)      ld1     t2=[src1],2)
 477EK(.ex_handler_short, (p8)      ld1     t3=[src0],2)
 478        cmp.le  p11,p0 = 6,r30
 479EX(.ex_handler_short, (p6)      st1     [dst0] = t1,2)
 480        cmp.le  p12,p0 = 7,r30
 481        ;;
 482EX(.ex_handler_short, (p9)      ld1     t4=[src1],2)
 483EK(.ex_handler_short, (p10)     ld1     t5=[src0],2)
 484EX(.ex_handler_short, (p7)      st1     [dst1] = t2,2)
 485EK(.ex_handler_short, (p8)      st1     [dst0] = t3,2)
 486        ;;
 487EX(.ex_handler_short, (p11)     ld1     t6=[src1],2)
 488EK(.ex_handler_short, (p12)     ld1     t7=[src0],2)
 489        cmp.eq  p6,p7=r28,r29
 490EX(.ex_handler_short, (p9)      st1     [dst1] = t4,2)
 491EK(.ex_handler_short, (p10)     st1     [dst0] = t5,2)
 492        sub     in2=in2,r30
 493        ;;
 494EX(.ex_handler_short, (p11)     st1     [dst1] = t6,2)
 495EK(.ex_handler_short, (p12)     st1     [dst0] = t7)
 496        add     dst0=in0,r30    // setup arguments
 497        add     src0=in1,r30
 498(p6)    br.cond.dptk .aligned_src
 499(p7)    br.cond.dpnt .unaligned_src
 500        ;;
 501
 502/* main loop body in jump table format */
 503#define COPYU(shift)                                                                    \
 5041:                                                                                      \
 505EX(.ex_handler,  (p16)  ld8     r32=[src0],8);          /* 1 */                         \
 506EK(.ex_handler,  (p16)  ld8     r36=[src1],8);                                          \
 507                 (p17)  shrp    r35=r33,r34,shift;;     /* 1 */                         \
 508EX(.ex_handler,  (p6)   ld8     r22=[src1]);    /* common, prime for tail section */    \
 509                 nop.m  0;                                                              \
 510                 (p16)  shrp    r38=r36,r37,shift;                                      \
 511EX(.ex_handler,  (p17)  st8     [dst0]=r35,8);          /* 1 */                         \
 512EK(.ex_handler,  (p17)  st8     [dst1]=r39,8);                                          \
 513                 br.ctop.dptk.few 1b;;                                                  \
 514                 (p7)   add     src1=-8,src1;   /* back out for <8 byte case */         \
 515                 shrp   r21=r22,r38,shift;      /* speculative work */                  \
 516                 br.sptk.few .unaligned_src_tail /* branch out of jump table */         \
 517                 ;;
 518        TEXT_ALIGN(32)
 519.jump_table:
 520        COPYU(8)        // unaligned cases
 521.jmp1:
 522        COPYU(16)
 523        COPYU(24)
 524        COPYU(32)
 525        COPYU(40)
 526        COPYU(48)
 527        COPYU(56)
 528
 529#undef A
 530#undef B
 531#undef C
 532#undef D
 533
 534/*
 535 * Due to lack of local tag support in gcc 2.x assembler, it is not clear which
 536 * instruction failed in the bundle.  The exception algorithm is that we
 537 * first figure out the faulting address, then detect if there is any
 538 * progress made on the copy, if so, redo the copy from last known copied
 539 * location up to the faulting address (exclusive). In the copy_from_user
 540 * case, remaining byte in kernel buffer will be zeroed.
 541 *
 542 * Take copy_from_user as an example, in the code there are multiple loads
 543 * in a bundle and those multiple loads could span over two pages, the
 544 * faulting address is calculated as page_round_down(max(src0, src1)).
 545 * This is based on knowledge that if we can access one byte in a page, we
 546 * can access any byte in that page.
 547 *
 548 * predicate used in the exception handler:
 549 * p6-p7: direction
 550 * p10-p11: src faulting addr calculation
 551 * p12-p13: dst faulting addr calculation
 552 */
 553
 554#define A       r19
 555#define B       r20
 556#define C       r21
 557#define D       r22
 558#define F       r28
 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 left along
 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        mov     r8=0
 640        mov     saved_retval = D
 641        mov     saved_rtlink = b0
 642
 643        add     out0=saved_in0, B
 644        add     out1=saved_in1, B
 645        mov     out2=C
 646(p8)    br.call.sptk.few b0=__copy_user // recursive call
 647        ;;
 648
 649        add     saved_retval=saved_retval,r8    // above might return non-zero value
 650        ;;
 651
 652        mov     retval=saved_retval
 653        mov     ar.pfs=saved_pfs_stack
 654        mov     b0=saved_rtlink
 655        br.ret.sptk.many rp
 656
 657/* end of McKinley specific optimization */
 658END(__copy_user)
 659EXPORT_SYMBOL(__copy_user)
 660