root/arch/ia64/lib/memcpy_mck.S

   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 
  75 GLOBAL_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         ;;
  82 END(memcpy)
  83 EXPORT_SYMBOL(memcpy)
  84 GLOBAL_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)
 156 1:
 157 EX(.ex_handler, (p16)   ld8     r34=[src0],16)
 158 EK(.ex_handler, (p16)   ld8     r38=[src1],16)
 159 EX(.ex_handler, (p17)   st8     [dst0]=r33,16)
 160 EK(.ex_handler, (p17)   st8     [dst1]=r37,16)
 161         ;;
 162 EX(.ex_handler, (p16)   ld8     r32=[src0],16)
 163 EK(.ex_handler, (p16)   ld8     r36=[src1],16)
 164 EX(.ex_handler, (p16)   st8     [dst0]=r34,16)
 165 EK(.ex_handler, (p16)   st8     [dst1]=r38,16)
 166         br.ctop.dptk.few 1b
 167         ;;
 168 
 169 .aligned_src_tail:
 170 EX(.ex_handler, (p6)    ld8     t1=[src0])
 171         mov     ar.lc=saved_lc
 172         mov     ar.pfs=saved_pfs
 173 EX(.ex_hndlr_s, (p7)    ld8     t2=[src1],8)
 174         cmp.le  p8,p0=24,tmp
 175         and     r21=-8,tmp
 176         ;;
 177 EX(.ex_hndlr_s, (p8)    ld8     t3=[src1])
 178 EX(.ex_handler, (p6)    st8     [dst0]=t1)      // store byte 1
 179         and     in2=7,tmp       // remaining length
 180 EX(.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         ;;
 184 EX(.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:
 214 EX(.ex_hndlr_lcpy_1, (p[A])     ld8 v[A] = [src_pre_mem], 128)          // M0
 215 EK(.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:
 223 EX(.ex_handler, (p[D])  ld8 t2 = [src0], 3*8)                   // M0
 224 EK(.ex_handler, (p[D])  ld8 t4 = [src1], 3*8)                   // M1
 225 EX(.ex_handler_lcpy,    (p[B])  st8 [dst_pre_mem] = v[B], 128)          // M2 prefetch dst from memory
 226 EK(.ex_handler_lcpy,    (p[D])  st8 [dst_pre_l2] = n8, 128)             // M3 prefetch dst from L2
 227         ;;
 228 EX(.ex_handler_lcpy,    (p[A])  ld8 v[A] = [src_pre_mem], 128)          // M0 prefetch src from memory
 229 EK(.ex_handler_lcpy,    (p[C])  ld8 n8 = [src_pre_l2], 128)             // M1 prefetch src from L2
 230 EX(.ex_handler, (p[D])  st8 [dst0] =  t1, 8)                    // M2
 231 EK(.ex_handler, (p[D])  st8 [dst1] =  t3, 8)                    // M3
 232         ;;
 233 EX(.ex_handler, (p[D])  ld8  t5 = [src0], 8)
 234 EK(.ex_handler, (p[D])  ld8  t7 = [src1], 3*8)
 235 EX(.ex_handler, (p[D])  st8 [dst0] =  t2, 3*8)
 236 EK(.ex_handler, (p[D])  st8 [dst1] =  t4, 3*8)
 237         ;;
 238 EX(.ex_handler, (p[D])  ld8  t6 = [src0], 3*8)
 239 EK(.ex_handler, (p[D])  ld8 t10 = [src1], 8)
 240 EX(.ex_handler, (p[D])  st8 [dst0] =  t5, 8)
 241 EK(.ex_handler, (p[D])  st8 [dst1] =  t7, 3*8)
 242         ;;
 243 EX(.ex_handler, (p[D])  ld8  t9 = [src0], 3*8)
 244 EK(.ex_handler, (p[D])  ld8 t11 = [src1], 3*8)
 245 EX(.ex_handler, (p[D])  st8 [dst0] =  t6, 3*8)
 246 EK(.ex_handler, (p[D])  st8 [dst1] = t10, 8)
 247         ;;
 248 EX(.ex_handler, (p[D])  ld8 t12 = [src0], 8)
 249 EK(.ex_handler, (p[D])  ld8 t14 = [src1], 8)
 250 EX(.ex_handler, (p[D])  st8 [dst0] =  t9, 3*8)
 251 EK(.ex_handler, (p[D])  st8 [dst1] = t11, 3*8)
 252         ;;
 253 EX(.ex_handler, (p[D])  ld8 t13 = [src0], 4*8)
 254 EK(.ex_handler, (p[D])  ld8 t15 = [src1], 4*8)
 255 EX(.ex_handler, (p[D])  st8 [dst0] = t12, 8)
 256 EK(.ex_handler, (p[D])  st8 [dst1] = t14, 8)
 257         ;;
 258 EX(.ex_handler, (p[C])  ld8  t1 = [src0], 8)
 259 EK(.ex_handler, (p[C])  ld8  t3 = [src1], 8)
 260 EX(.ex_handler, (p[D])  st8 [dst0] = t13, 4*8)
 261 EK(.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)
 313 1:      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         ;;
 324 EX(.ex_handler, (p9)    ld8     r33=[src0],8)   // loop primer
 325 EK(.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
 336 1:
 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:
 355 EX(.ex_handler, (p6)    ld8     r37=[src1],8)
 356         add     src0=8,src0
 357 (p6)    shl     r25=r30,3
 358         ;;
 359 EX(.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  */
 395 EX(.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 
 416 EX(.ex_handler_short, (p8)      ld1     t1=[src0],2)
 417 EK(.ex_handler_short, (p10)     ld1     t2=[src1],2)
 418 (p9)    br.ret.dpnt rp          // 0 byte copy
 419         ;;
 420 
 421 EX(.ex_handler_short, (p8)      st1     [dst0]=t1,2)
 422 EK(.ex_handler_short, (p10)     st1     [dst1]=t2,2)
 423 (p11)   br.ret.dpnt rp          // 1 byte copy
 424 
 425 EX(.ex_handler_short, (p12)     ld1     t3=[src0],2)
 426 EK(.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 
 434 EX(.ex_handler_short, (p12)     st1     [dst0]=t3,2)
 435 EK(.ex_handler_short, (p14)     st1     [dst1]=t4,2)
 436 (p15)   br.ret.dpnt rp          // 3 byte copy
 437         ;;
 438 
 439 EX(.ex_handler_short, (p6)      ld1     t5=[src0],2)
 440 EK(.ex_handler_short, (p8)      ld1     t6=[src1],2)
 441 (p7)    br.ret.dpnt rp          // 4 byte copy
 442         ;;
 443 
 444 EX(.ex_handler_short, (p6)      st1     [dst0]=t5,2)
 445 EK(.ex_handler_short, (p8)      st1     [dst1]=t6,2)
 446 (p9)    br.ret.dptk rp          // 5 byte copy
 447 
 448 EX(.ex_handler_short, (p10)     ld1     t7=[src0],2)
 449 (p11)   br.ret.dptk rp          // 6 byte copy
 450         ;;
 451 
 452 EX(.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
 472 EX(.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         ;;
 476 EX(.ex_handler_short, (p7)      ld1     t2=[src1],2)
 477 EK(.ex_handler_short, (p8)      ld1     t3=[src0],2)
 478         cmp.le  p11,p0 = 6,r30
 479 EX(.ex_handler_short, (p6)      st1     [dst0] = t1,2)
 480         cmp.le  p12,p0 = 7,r30
 481         ;;
 482 EX(.ex_handler_short, (p9)      ld1     t4=[src1],2)
 483 EK(.ex_handler_short, (p10)     ld1     t5=[src0],2)
 484 EX(.ex_handler_short, (p7)      st1     [dst1] = t2,2)
 485 EK(.ex_handler_short, (p8)      st1     [dst0] = t3,2)
 486         ;;
 487 EX(.ex_handler_short, (p11)     ld1     t6=[src1],2)
 488 EK(.ex_handler_short, (p12)     ld1     t7=[src0],2)
 489         cmp.eq  p6,p7=r28,r29
 490 EX(.ex_handler_short, (p9)      st1     [dst1] = t4,2)
 491 EK(.ex_handler_short, (p10)     st1     [dst0] = t5,2)
 492         sub     in2=in2,r30
 493         ;;
 494 EX(.ex_handler_short, (p11)     st1     [dst1] = t6,2)
 495 EK(.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)                                                                    \
 504 1:                                                                                      \
 505 EX(.ex_handler,  (p16)  ld8     r32=[src0],8);          /* 1 */                         \
 506 EK(.ex_handler,  (p16)  ld8     r36=[src1],8);                                          \
 507                  (p17)  shrp    r35=r33,r34,shift;;     /* 1 */                         \
 508 EX(.ex_handler,  (p6)   ld8     r22=[src1]);    /* common, prime for tail section */    \
 509                  nop.m  0;                                                              \
 510                  (p16)  shrp    r38=r36,r37,shift;                                      \
 511 EX(.ex_handler,  (p17)  st8     [dst0]=r35,8);          /* 1 */                         \
 512 EK(.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 */
 658 END(__copy_user)
 659 EXPORT_SYMBOL(__copy_user)