arch/alpha/kernel/entry.S

   1 /*
   2  * arch/alpha/kernel/entry.S
   3  *
   4  * Kernel entry-points.
   5  */
   6
   7 #include <linux/config.h>
   8 #include <asm/asm_offsets.h>
   9 #include <asm/thread_info.h>
  10 #include <asm/pal.h>
  11 #include <asm/errno.h>
  12 #include <asm/unistd.h>
  13
  14         .text
  15         .set noat
  16
  17 /* Stack offsets.  */
  18 #define SP_OFF                  184
  19 #define SWITCH_STACK_SIZE       320
  20
  21 /*
  22  * This defines the normal kernel pt-regs layout.
  23  *
  24  * regs 9-15 preserved by C code
  25  * regs 16-18 saved by PAL-code
  26  * regs 29-30 saved and set up by PAL-code
  27  * JRP - Save regs 16-18 in a special area of the stack, so that
  28  * the palcode-provided values are available to the signal handler.
  29  */
  30
  31 #define SAVE_ALL                        \
  32         subq    $sp, SP_OFF, $sp;       \
  33         stq     $0, 0($sp);             \
  34         stq     $1, 8($sp);             \
  35         stq     $2, 16($sp);            \
  36         stq     $3, 24($sp);            \
  37         stq     $4, 32($sp);            \
  38         stq     $28, 144($sp);          \
  39         lda     $2, alpha_mv;           \
  40         stq     $5, 40($sp);            \
  41         stq     $6, 48($sp);            \
  42         stq     $7, 56($sp);            \
  43         stq     $8, 64($sp);            \
  44         stq     $19, 72($sp);           \
  45         stq     $20, 80($sp);           \
  46         stq     $21, 88($sp);           \
  47         ldq     $2, HAE_CACHE($2);      \
  48         stq     $22, 96($sp);           \
  49         stq     $23, 104($sp);          \
  50         stq     $24, 112($sp);          \
  51         stq     $25, 120($sp);          \
  52         stq     $26, 128($sp);          \
  53         stq     $27, 136($sp);          \
  54         stq     $2, 152($sp);           \
  55         stq     $16, 160($sp);          \
  56         stq     $17, 168($sp);          \
  57         stq     $18, 176($sp)
  58
  59 #define RESTORE_ALL                     \
  60         lda     $19, alpha_mv;          \
  61         ldq     $0, 0($sp);             \
  62         ldq     $1, 8($sp);             \
  63         ldq     $2, 16($sp);            \
  64         ldq     $3, 24($sp);            \
  65         ldq     $21, 152($sp);          \
  66         ldq     $20, HAE_CACHE($19);    \
  67         ldq     $4, 32($sp);            \
  68         ldq     $5, 40($sp);            \
  69         ldq     $6, 48($sp);            \
  70         ldq     $7, 56($sp);            \
  71         subq    $20, $21, $20;          \
  72         ldq     $8, 64($sp);            \
  73         beq     $20, 99f;               \
  74         ldq     $20, HAE_REG($19);      \
  75         stq     $21, HAE_CACHE($19);    \
  76         stq     $21, 0($20);            \
  77         ldq     $0, 0($sp);             \
  78         ldq     $1, 8($sp);             \
  79 99:;                                    \
  80         ldq     $19, 72($sp);           \
  81         ldq     $20, 80($sp);           \
  82         ldq     $21, 88($sp);           \
  83         ldq     $22, 96($sp);           \
  84         ldq     $23, 104($sp);          \
  85         ldq     $24, 112($sp);          \
  86         ldq     $25, 120($sp);          \
  87         ldq     $26, 128($sp);          \
  88         ldq     $27, 136($sp);          \
  89         ldq     $28, 144($sp);          \
  90         addq    $sp, SP_OFF, $sp
  91
  92 /*
  93  * Non-syscall kernel entry points.
  94  */
  95
  96         .align  4
  97         .globl  entInt
  98         .ent    entInt
  99 entInt:
 100         SAVE_ALL
 101         lda     $8, 0x3fff
 102         lda     $26, ret_from_sys_call
 103         bic     $sp, $8, $8
 104         mov     $sp, $19
 105         jsr     $31, do_entInt
 106 .end entInt
 107
 108         .align  4
 109         .globl  entArith
 110         .ent    entArith
 111 entArith:
 112         SAVE_ALL
 113         lda     $8, 0x3fff
 114         lda     $26, ret_from_sys_call
 115         bic     $sp, $8, $8
 116         mov     $sp, $18
 117         jsr     $31, do_entArith
 118 .end entArith
 119
 120         .align  4
 121         .globl  entMM
 122         .ent    entMM
 123 entMM:
 124         SAVE_ALL
 125 /* save $9 - $15 so the inline exception code can manipulate them.  */
 126         subq    $sp, 56, $sp
 127         stq     $9, 0($sp)
 128         stq     $10, 8($sp)
 129         stq     $11, 16($sp)
 130         stq     $12, 24($sp)
 131         stq     $13, 32($sp)
 132         stq     $14, 40($sp)
 133         stq     $15, 48($sp)
 134         addq    $sp, 56, $19
 135 /* handle the fault */
 136         lda     $8, 0x3fff
 137         bic     $sp, $8, $8
 138         jsr     $26, do_page_fault
 139 /* reload the registers after the exception code played.  */
 140         ldq     $9, 0($sp)
 141         ldq     $10, 8($sp)
 142         ldq     $11, 16($sp)
 143         ldq     $12, 24($sp)
 144         ldq     $13, 32($sp)
 145         ldq     $14, 40($sp)
 146         ldq     $15, 48($sp)
 147         addq    $sp, 56, $sp
 148 /* finish up the syscall as normal.  */
 149         br      ret_from_sys_call
 150 .end entMM
 151
 152         .align  4
 153         .globl  entIF
 154         .ent    entIF
 155 entIF:
 156         SAVE_ALL
 157         lda     $8, 0x3fff
 158         lda     $26, ret_from_sys_call
 159         bic     $sp, $8, $8
 160         mov     $sp, $17
 161         jsr     $31, do_entIF
 162 .end entIF
 163
 164         .align  4
 165         .globl  entUna
 166         .ent    entUna
 167 entUna:
 168         lda     $sp, -256($sp)
 169         stq     $0, 0($sp)
 170         ldq     $0, 256($sp)    /* get PS */
 171         stq     $1, 8($sp)
 172         stq     $2, 16($sp)
 173         stq     $3, 24($sp)
 174         and     $0, 8, $0               /* user mode? */
 175         stq     $4, 32($sp)
 176         bne     $0, entUnaUser  /* yup -> do user-level unaligned fault */
 177         stq     $5, 40($sp)
 178         stq     $6, 48($sp)
 179         stq     $7, 56($sp)
 180         stq     $8, 64($sp)
 181         stq     $9, 72($sp)
 182         stq     $10, 80($sp)
 183         stq     $11, 88($sp)
 184         stq     $12, 96($sp)
 185         stq     $13, 104($sp)
 186         stq     $14, 112($sp)
 187         stq     $15, 120($sp)
 188         /* 16-18 PAL-saved */
 189         stq     $19, 152($sp)
 190         stq     $20, 160($sp)
 191         stq     $21, 168($sp)
 192         stq     $22, 176($sp)
 193         stq     $23, 184($sp)
 194         stq     $24, 192($sp)
 195         stq     $25, 200($sp)
 196         stq     $26, 208($sp)
 197         stq     $27, 216($sp)
 198         stq     $28, 224($sp)
 199         stq     $gp, 232($sp)
 200         lda     $8, 0x3fff
 201         stq     $31, 248($sp)
 202         bic     $sp, $8, $8
 203         jsr     $26, do_entUna
 204         ldq     $0, 0($sp)
 205         ldq     $1, 8($sp)
 206         ldq     $2, 16($sp)
 207         ldq     $3, 24($sp)
 208         ldq     $4, 32($sp)
 209         ldq     $5, 40($sp)
 210         ldq     $6, 48($sp)
 211         ldq     $7, 56($sp)
 212         ldq     $8, 64($sp)
 213         ldq     $9, 72($sp)
 214         ldq     $10, 80($sp)
 215         ldq     $11, 88($sp)
 216         ldq     $12, 96($sp)
 217         ldq     $13, 104($sp)
 218         ldq     $14, 112($sp)
 219         ldq     $15, 120($sp)
 220         /* 16-18 PAL-saved */
 221         ldq     $19, 152($sp)
 222         ldq     $20, 160($sp)
 223         ldq     $21, 168($sp)
 224         ldq     $22, 176($sp)
 225         ldq     $23, 184($sp)
 226         ldq     $24, 192($sp)
 227         ldq     $25, 200($sp)
 228         ldq     $26, 208($sp)
 229         ldq     $27, 216($sp)
 230         ldq     $28, 224($sp)
 231         ldq     $gp, 232($sp)
 232         lda     $sp, 256($sp)
 233         call_pal PAL_rti
 234 .end entUna
 235
 236         .align  4
 237         .ent    entUnaUser
 238 entUnaUser:
 239         ldq     $0, 0($sp)      /* restore original $0 */
 240         lda     $sp, 256($sp)   /* pop entUna's stack frame */
 241         SAVE_ALL                /* setup normal kernel stack */
 242         lda     $sp, -56($sp)
 243         stq     $9, 0($sp)
 244         stq     $10, 8($sp)
 245         stq     $11, 16($sp)
 246         stq     $12, 24($sp)
 247         stq     $13, 32($sp)
 248         stq     $14, 40($sp)
 249         stq     $15, 48($sp)
 250         lda     $8, 0x3fff
 251         addq    $sp, 56, $19
 252         bic     $sp, $8, $8
 253         jsr     $26, do_entUnaUser
 254         ldq     $9, 0($sp)
 255         ldq     $10, 8($sp)
 256         ldq     $11, 16($sp)
 257         ldq     $12, 24($sp)
 258         ldq     $13, 32($sp)
 259         ldq     $14, 40($sp)
 260         ldq     $15, 48($sp)
 261         lda     $sp, 56($sp)
 262         br      ret_from_sys_call
 263 .end entUnaUser
 264
 265         .align  4
 266         .globl  entDbg
 267         .ent    entDbg
 268 entDbg:
 269         SAVE_ALL
 270         lda     $8, 0x3fff
 271         lda     $26, ret_from_sys_call
 272         bic     $sp, $8, $8
 273         mov     $sp, $16
 274         jsr     $31, do_entDbg
 275 .end entDbg
 276 \f
 277 /*
 278  * The system call entry point is special.  Most importantly, it looks
 279  * like a function call to userspace as far as clobbered registers.  We
 280  * do preserve the argument registers (for syscall restarts) and $26
 281  * (for leaf syscall functions).
 282  *
 283  * So much for theory.  We don't take advantage of this yet.
 284  *
 285  * Note that a0-a2 are not saved by PALcode as with the other entry points.
 286  */
 287
 288         .align  4
 289         .globl  entSys
 290         .globl  ret_from_sys_call
 291         .ent    entSys
 292 entSys:
 293         SAVE_ALL
 294         lda     $8, 0x3fff
 295         bic     $sp, $8, $8
 296         lda     $4, NR_SYSCALLS($31)
 297         stq     $16, SP_OFF+24($sp)
 298         lda     $5, sys_call_table
 299         lda     $27, sys_ni_syscall
 300         cmpult  $0, $4, $4
 301         ldl     $3, TI_FLAGS($8)
 302         stq     $17, SP_OFF+32($sp)
 303         s8addq  $0, $5, $5
 304         stq     $18, SP_OFF+40($sp)
 305         blbs    $3, strace
 306         beq     $4, 1f
 307         ldq     $27, 0($5)
 308 1:      jsr     $26, ($27), alpha_ni_syscall
 309         ldgp    $gp, 0($26)
 310         blt     $0, $syscall_error      /* the call failed */
 311         stq     $0, 0($sp)
 312         stq     $31, 72($sp)            /* a3=0 => no error */
 313
 314         .align  4
 315 ret_from_sys_call:
 316         cmovne  $26, 0, $19             /* $19 = 0 => non-restartable */
 317         ldq     $0, SP_OFF($sp)
 318         and     $0, 8, $0
 319         beq     $0, restore_all
 320 ret_from_reschedule:
 321         /* Make sure need_resched and sigpending don't change between
 322                 sampling and the rti.  */
 323         lda     $16, 7
 324         call_pal PAL_swpipl
 325         ldl     $5, TI_FLAGS($8)
 326         and     $5, _TIF_WORK_MASK, $2
 327         bne     $5, work_pending
 328 restore_all:
 329         RESTORE_ALL
 330         call_pal PAL_rti
 331
 332         .align 3
 333 $syscall_error:
 334         /*
 335          * Some system calls (e.g., ptrace) can return arbitrary
 336          * values which might normally be mistaken as error numbers.
 337          * Those functions must zero $0 (v0) directly in the stack
 338          * frame to indicate that a negative return value wasn't an
 339          * error number..
 340          */
 341         ldq     $19, 0($sp)     /* old syscall nr (zero if success) */
 342         beq     $19, $ret_success
 343
 344         ldq     $20, 72($sp)    /* .. and this a3 */
 345         subq    $31, $0, $0     /* with error in v0 */
 346         addq    $31, 1, $1      /* set a3 for errno return */
 347         stq     $0, 0($sp)
 348         mov     $31, $26        /* tell "ret_from_sys_call" we can restart */
 349         stq     $1, 72($sp)     /* a3 for return */
 350         br      ret_from_sys_call
 351
 352 $ret_success:
 353         stq     $0, 0($sp)
 354         stq     $31, 72($sp)    /* a3=0 => no error */
 355         br      ret_from_sys_call
 356 .end entSys
 357
 358 /*
 359  * Do all cleanup when returning from all interrupts and system calls.
 360  *
 361  * Arguments:
 362  *       $5: TI_FLAGS.
 363  *       $8: current.
 364  *      $19: The old syscall number, or zero if this is not a return
 365  *           from a syscall that errored and is possibly restartable.
 366  *      $20: Error indication.
 367  */
 368
 369         .align  4
 370         .ent    work_pending
 371 work_pending:
 372         and     $5, _TIF_NEED_RESCHED, $2
 373         beq     $2, $work_notifysig
 374
 375 $work_resched:
 376         subq    $sp, 16, $sp
 377         stq     $19, 0($sp)              /* save syscall nr */
 378         stq     $20, 8($sp)              /* and error indication (a3) */
 379         jsr     $26, schedule
 380         ldq     $19, 0($sp)
 381         ldq     $20, 8($sp)
 382         addq    $sp, 16, $sp
 383         /* Make sure need_resched and sigpending don't change between
 384                 sampling and the rti.  */
 385         lda     $16, 7
 386         call_pal PAL_swpipl
 387         ldl     $5, TI_FLAGS($8)
 388         and     $5, _TIF_WORK_MASK, $2
 389         beq     $2, restore_all
 390         and     $5, _TIF_NEED_RESCHED, $2
 391         bne     $2, $work_resched
 392
 393 $work_notifysig:
 394         mov     $sp, $17
 395         br      $1, do_switch_stack
 396         mov     $5, $21
 397         mov     $sp, $18
 398         mov     $31, $16
 399         jsr     $26, do_notify_resume
 400         bsr     $1, undo_switch_stack
 401         br      restore_all
 402 .end work_pending
 403
 404 /*
 405  * PTRACE syscall handler
 406  */
 407
 408         .align  4
 409         .ent    strace
 410 strace:
 411         /* set up signal stack, call syscall_trace */
 412         bsr     $1, do_switch_stack
 413         jsr     $26, syscall_trace
 414         bsr     $1, undo_switch_stack
 415
 416         /* get the system call number and the arguments back.. */
 417         ldq     $0, 0($sp)
 418         ldq     $16, SP_OFF+24($sp)
 419         ldq     $17, SP_OFF+32($sp)
 420         ldq     $18, SP_OFF+40($sp)
 421         ldq     $19, 72($sp)
 422         ldq     $20, 80($sp)
 423         ldq     $21, 88($sp)
 424
 425         /* get the system call pointer.. */
 426         lda     $1, NR_SYSCALLS($31)
 427         lda     $2, sys_call_table
 428         lda     $27, alpha_ni_syscall
 429         cmpult  $0, $1, $1
 430         s8addq  $0, $2, $2
 431         beq     $1, 1f
 432         ldq     $27, 0($2)
 433 1:      jsr     $26, ($27), sys_gettimeofday
 434         ldgp    $gp, 0($26)
 435
 436         /* check return.. */
 437         blt     $0, $strace_error       /* the call failed */
 438         stq     $31, 72($sp)            /* a3=0 => no error */
 439 $strace_success:
 440         stq     $0, 0($sp)              /* save return value */
 441
 442         bsr     $1, do_switch_stack
 443         jsr     $26, syscall_trace
 444         bsr     $1, undo_switch_stack
 445         br      $31, ret_from_sys_call
 446
 447         .align  3
 448 $strace_error:
 449         ldq     $19, 0($sp)     /* old syscall nr (zero if success) */
 450         beq     $19, $strace_success
 451         ldq     $20, 72($sp)    /* .. and this a3 */
 452
 453         subq    $31, $0, $0     /* with error in v0 */
 454         addq    $31, 1, $1      /* set a3 for errno return */
 455         stq     $0, 0($sp)
 456         stq     $1, 72($sp)     /* a3 for return */
 457
 458         bsr     $1, do_switch_stack
 459         mov     $19, $9         /* save old syscall number */
 460         mov     $20, $10        /* save old a3 */
 461         jsr     $26, syscall_trace
 462         mov     $9, $19
 463         mov     $10, $20
 464         bsr     $1, undo_switch_stack
 465
 466         mov     $31, $26        /* tell "ret_from_sys_call" we can restart */
 467         br      ret_from_sys_call
 468 .end strace
 469 \f
 470 /*
 471  * Save and restore the switch stack -- aka the balance of the user context.
 472  */
 473
 474         .align  4
 475         .ent    do_switch_stack
 476 do_switch_stack:
 477         lda     $sp, -SWITCH_STACK_SIZE($sp)
 478         stq     $9, 0($sp)
 479         stq     $10, 8($sp)
 480         stq     $11, 16($sp)
 481         stq     $12, 24($sp)
 482         stq     $13, 32($sp)
 483         stq     $14, 40($sp)
 484         stq     $15, 48($sp)
 485         stq     $26, 56($sp)
 486         stt     $f0, 64($sp)
 487         stt     $f1, 72($sp)
 488         stt     $f2, 80($sp)
 489         stt     $f3, 88($sp)
 490         stt     $f4, 96($sp)
 491         stt     $f5, 104($sp)
 492         stt     $f6, 112($sp)
 493         stt     $f7, 120($sp)
 494         stt     $f8, 128($sp)
 495         stt     $f9, 136($sp)
 496         stt     $f10, 144($sp)
 497         stt     $f11, 152($sp)
 498         stt     $f12, 160($sp)
 499         stt     $f13, 168($sp)
 500         stt     $f14, 176($sp)
 501         stt     $f15, 184($sp)
 502         stt     $f16, 192($sp)
 503         stt     $f17, 200($sp)
 504         stt     $f18, 208($sp)
 505         stt     $f19, 216($sp)
 506         stt     $f20, 224($sp)
 507         stt     $f21, 232($sp)
 508         stt     $f22, 240($sp)
 509         stt     $f23, 248($sp)
 510         stt     $f24, 256($sp)
 511         stt     $f25, 264($sp)
 512         stt     $f26, 272($sp)
 513         stt     $f27, 280($sp)
 514         mf_fpcr $f0             # get fpcr
 515         stt     $f28, 288($sp)
 516         stt     $f29, 296($sp)
 517         stt     $f30, 304($sp)
 518         stt     $f0, 312($sp)   # save fpcr in slot of $f31
 519         ldt     $f0, 64($sp)    # dont let "do_switch_stack" change fp state.
 520         ret     $31, ($1), 1
 521 .end do_switch_stack
 522
 523         .align  4
 524         .ent    undo_switch_stack
 525 undo_switch_stack:
 526         ldq     $9, 0($sp)
 527         ldq     $10, 8($sp)
 528         ldq     $11, 16($sp)
 529         ldq     $12, 24($sp)
 530         ldq     $13, 32($sp)
 531         ldq     $14, 40($sp)
 532         ldq     $15, 48($sp)
 533         ldq     $26, 56($sp)
 534         ldt     $f30, 312($sp)  # get saved fpcr
 535         ldt     $f0, 64($sp)
 536         ldt     $f1, 72($sp)
 537         ldt     $f2, 80($sp)
 538         ldt     $f3, 88($sp)
 539         mt_fpcr $f30            # install saved fpcr
 540         ldt     $f4, 96($sp)
 541         ldt     $f5, 104($sp)
 542         ldt     $f6, 112($sp)
 543         ldt     $f7, 120($sp)
 544         ldt     $f8, 128($sp)
 545         ldt     $f9, 136($sp)
 546         ldt     $f10, 144($sp)
 547         ldt     $f11, 152($sp)
 548         ldt     $f12, 160($sp)
 549         ldt     $f13, 168($sp)
 550         ldt     $f14, 176($sp)
 551         ldt     $f15, 184($sp)
 552         ldt     $f16, 192($sp)
 553         ldt     $f17, 200($sp)
 554         ldt     $f18, 208($sp)
 555         ldt     $f19, 216($sp)
 556         ldt     $f20, 224($sp)
 557         ldt     $f21, 232($sp)
 558         ldt     $f22, 240($sp)
 559         ldt     $f23, 248($sp)
 560         ldt     $f24, 256($sp)
 561         ldt     $f25, 264($sp)
 562         ldt     $f26, 272($sp)
 563         ldt     $f27, 280($sp)
 564         ldt     $f28, 288($sp)
 565         ldt     $f29, 296($sp)
 566         ldt     $f30, 304($sp)
 567         lda     $sp, SWITCH_STACK_SIZE($sp)
 568         ret     $31, ($1), 1
 569 .end undo_switch_stack
 570 \f
 571 /*
 572  * The meat of the context switch code.
 573  */
 574
 575         .align  4
 576         .globl  alpha_switch_to
 577         .ent    alpha_switch_to
 578 alpha_switch_to:
 579         .prologue 0
 580         bsr     $1, do_switch_stack
 581         call_pal PAL_swpctx
 582         lda     $8, 0x3fff
 583         bsr     $1, undo_switch_stack
 584         bic     $sp, $8, $8
 585         mov     $17, $0
 586         ret
 587 .end alpha_switch_to
 588
 589 /*
 590  * New processes begin life here.
 591  */
 592
 593         .globl  ret_from_fork
 594         .align  4
 595         .ent    ret_from_fork
 596 ret_from_fork:
 597         lda     $26, ret_from_sys_call
 598         mov     $17, $16
 599         jmp     $31, schedule_tail
 600 .end ret_from_fork
 601
 602 /*
 603  * kernel_thread(fn, arg, clone_flags)
 604  */
 605         .align 4
 606         .globl  kernel_thread
 607         .ent    kernel_thread
 608 kernel_thread:
 609         /* We can be called from a module.  */
 610         ldgp    $gp, 0($27)
 611         .prologue 1
 612         subq    $sp, SP_OFF+6*8, $sp
 613         br      $1, 2f          /* load start address */
 614
 615         /* We've now "returned" from a fake system call.  */
 616         unop
 617         blt     $0, 1f          /* error?  */
 618         ldi     $1, 0x3fff
 619         beq     $20, 1f         /* parent or child?  */
 620
 621         bic     $sp, $1, $8     /* in child.  */
 622         jsr     $26, ($27)
 623         ldgp    $gp, 0($26)
 624         mov     $0, $16
 625         mov     $31, $26
 626         jmp     $31, sys_exit
 627
 628 1:      ret                     /* in parent.  */
 629
 630         .align 4
 631 2:      /* Fake a system call stack frame, as we can't do system calls
 632            from kernel space.  Note that we store FN and ARG as they
 633            need to be set up in the child for the call.  Also store $8
 634            and $26 for use in the parent.  */
 635         stq     $31, SP_OFF($sp)        /* ps */
 636         stq     $1, SP_OFF+8($sp)       /* pc */
 637         stq     $gp, SP_OFF+16($sp)     /* gp */
 638         stq     $16, 136($sp)           /* $27; FN for child */
 639         stq     $17, SP_OFF+24($sp)     /* $16; ARG for child */
 640         stq     $8, 64($sp)             /* $8 */
 641         stq     $26, 128($sp)           /* $26 */
 642         /* Avoid the HAE being gratuitously wrong, to avoid restoring it.  */
 643         ldq     $2, alpha_mv+HAE_CACHE
 644         stq     $2, 152($sp)            /* HAE */
 645
 646         /* Shuffle FLAGS to the front; add CLONE_VM.  */
 647         ldi     $1, CLONE_VM|CLONE_UNTRACED
 648         or      $18, $1, $16
 649         bsr     $26, sys_clone
 650
 651         /* We don't actually care for a3 success widgetry in the kernel.
 652            Not for positive errno values.  */
 653         stq     $0, 0($sp)              /* $0 */
 654         br      restore_all
 655 .end kernel_thread
 656
 657 /*
 658  * execve(path, argv, envp)
 659  */
 660         .align  4
 661         .globl  execve
 662         .ent    execve
 663 execve:
 664         /* We can be called from a module.  */
 665         ldgp    $gp, 0($27)
 666         lda     $sp, -(32+SIZEOF_PT_REGS+8)($sp)
 667         .frame  $sp, 32+SIZEOF_PT_REGS+8, $26, 0
 668         stq     $26, 0($sp)
 669         stq     $16, 8($sp)
 670         stq     $17, 16($sp)
 671         stq     $18, 24($sp)
 672         .prologue 1
 673
 674         lda     $16, 32($sp)
 675         lda     $17, 0
 676         lda     $18, SIZEOF_PT_REGS
 677         bsr     $26, memset             !samegp
 678
 679         /* Avoid the HAE being gratuitously wrong, which would cause us
 680            to do the whole turn off interrupts thing and restore it.  */
 681         ldq     $2, alpha_mv+HAE_CACHE
 682         stq     $2, 152+32($sp)
 683
 684         ldq     $16, 8($sp)
 685         ldq     $17, 16($sp)
 686         ldq     $18, 24($sp)
 687         lda     $19, 32($sp)
 688         bsr     $26, do_execve          !samegp
 689
 690         ldq     $26, 0($sp)
 691         bne     $0, 1f                  /* error! */
 692
 693         /* Move the temporary pt_regs struct from its current location
 694            to the top of the kernel stack frame.  See copy_thread for
 695            details for a normal process.  */
 696         lda     $16, 0x4000 - SIZEOF_PT_REGS($8)
 697         lda     $17, 32($sp)
 698         lda     $18, SIZEOF_PT_REGS
 699         bsr     $26, memmove            !samegp
 700
 701         /* Take that over as our new stack frame and visit userland!  */
 702         lda     $sp, 0x4000 - SIZEOF_PT_REGS($8)
 703         br      $31, ret_from_sys_call
 704
 705 1:      lda     $sp, 32+SIZEOF_PT_REGS+8($sp)
 706         ret
 707 .end execve
 708
 709 \f
 710 /*
 711  * Special system calls.  Most of these are special in that they either
 712  * have to play switch_stack games or in some way use the pt_regs struct.
 713  */
 714         .align  4
 715         .globl  sys_fork
 716         .ent    sys_fork
 717 sys_fork:
 718         .prologue 0
 719         mov     $sp, $21
 720         bsr     $1, do_switch_stack
 721         bis     $31, SIGCHLD, $16
 722         mov     $31, $17
 723         mov     $31, $18
 724         mov     $31, $19
 725         mov     $31, $20
 726         jsr     $26, alpha_clone
 727         bsr     $1, undo_switch_stack
 728         ret
 729 .end sys_fork
 730
 731         .align  4
 732         .globl  sys_clone
 733         .ent    sys_clone
 734 sys_clone:
 735         .prologue 0
 736         mov     $sp, $21
 737         bsr     $1, do_switch_stack
 738         /* $16, $17, $18, $19, $20 come from the user.  */
 739         jsr     $26, alpha_clone
 740         bsr     $1, undo_switch_stack
 741         ret
 742 .end sys_clone
 743
 744         .align  4
 745         .globl  sys_vfork
 746         .ent    sys_vfork
 747 sys_vfork:
 748         .prologue 0
 749         mov     $sp, $16
 750         bsr     $1, do_switch_stack
 751         jsr     $26, alpha_vfork
 752         bsr     $1, undo_switch_stack
 753         ret
 754 .end sys_vfork
 755
 756         .align  4
 757         .globl  sys_sigreturn
 758         .ent    sys_sigreturn
 759 sys_sigreturn:
 760         .prologue 0
 761         mov     $sp, $17
 762         lda     $18, -SWITCH_STACK_SIZE($sp)
 763         lda     $sp, -SWITCH_STACK_SIZE($sp)
 764         jsr     $26, do_sigreturn
 765         br      $1, undo_switch_stack
 766         br      ret_from_sys_call
 767 .end sys_sigreturn
 768
 769         .align  4
 770         .globl  sys_rt_sigreturn
 771         .ent    sys_rt_sigreturn
 772 sys_rt_sigreturn:
 773         .prologue 0
 774         mov     $sp, $17
 775         lda     $18, -SWITCH_STACK_SIZE($sp)
 776         lda     $sp, -SWITCH_STACK_SIZE($sp)
 777         jsr     $26, do_rt_sigreturn
 778         br      $1, undo_switch_stack
 779         br      ret_from_sys_call
 780 .end sys_rt_sigreturn
 781
 782         .align  4
 783         .globl  sys_sigsuspend
 784         .ent    sys_sigsuspend
 785 sys_sigsuspend:
 786         .prologue 0
 787         mov     $sp, $17
 788         br      $1, do_switch_stack
 789         mov     $sp, $18
 790         subq    $sp, 16, $sp
 791         stq     $26, 0($sp)
 792         jsr     $26, do_sigsuspend
 793         ldq     $26, 0($sp)
 794         lda     $sp, SWITCH_STACK_SIZE+16($sp)
 795         ret
 796 .end sys_sigsuspend
 797
 798         .align  4
 799         .globl  sys_rt_sigsuspend
 800         .ent    sys_rt_sigsuspend
 801 sys_rt_sigsuspend:
 802         .prologue 0
 803         mov     $sp, $18
 804         br      $1, do_switch_stack
 805         mov     $sp, $19
 806         subq    $sp, 16, $sp
 807         stq     $26, 0($sp)
 808         jsr     $26, do_rt_sigsuspend
 809         ldq     $26, 0($sp)
 810         lda     $sp, SWITCH_STACK_SIZE+16($sp)
 811         ret
 812 .end sys_rt_sigsuspend
 813
 814         .align  4
 815         .globl  sys_sethae
 816         .ent    sys_sethae
 817 sys_sethae:
 818         .prologue 0
 819         stq     $16, 152($sp)
 820         ret
 821 .end sys_sethae
 822
 823         .align  4
 824         .globl  osf_getpriority
 825         .ent    osf_getpriority
 826 osf_getpriority:
 827         lda     $sp, -16($sp)
 828         stq     $26, 0($sp)
 829         .prologue 0
 830
 831         jsr     $26, sys_getpriority
 832
 833         ldq     $26, 0($sp)
 834         blt     $0, 1f
 835
 836         /* Return value is the unbiased priority, i.e. 20 - prio.
 837            This does result in negative return values, so signal
 838            no error by writing into the R0 slot.  */
 839         lda     $1, 20
 840         stq     $31, 16($sp)
 841         subl    $1, $0, $0
 842         unop
 843
 844 1:      lda     $sp, 16($sp)
 845         ret
 846 .end osf_getpriority
 847
 848         .align  4
 849         .globl  sys_getxuid
 850         .ent    sys_getxuid
 851 sys_getxuid:
 852         .prologue 0
 853         ldq     $2, TI_TASK($8)
 854         ldl     $0, TASK_UID($2)
 855         ldl     $1, TASK_EUID($2)
 856         stq     $1, 80($sp)
 857         ret
 858 .end sys_getxuid
 859
 860         .align  4
 861         .globl  sys_getxgid
 862         .ent    sys_getxgid
 863 sys_getxgid:
 864         .prologue 0
 865         ldq     $2, TI_TASK($8)
 866         ldl     $0, TASK_GID($2)
 867         ldl     $1, TASK_EGID($2)
 868         stq     $1, 80($sp)
 869         ret
 870 .end sys_getxgid
 871
 872         .align  4
 873         .globl  sys_getxpid
 874         .ent    sys_getxpid
 875 sys_getxpid:
 876         .prologue 0
 877         ldq     $2, TI_TASK($8)
 878
 879         /* See linux/kernel/timer.c sys_getppid for discussion
 880            about this loop.  */
 881         ldq     $3, TASK_REAL_PARENT($2)
 882 1:      ldl     $1, TASK_TGID($3)
 883 #ifdef CONFIG_SMP
 884         mov     $3, $4
 885         mb
 886         ldq     $3, TASK_REAL_PARENT($2)
 887         cmpeq   $3, $4, $4
 888         beq     $4, 1b
 889 #endif
 890         stq     $1, 80($sp)
 891         ldl     $0, TASK_TGID($2)
 892         ret
 893 .end sys_getxpid
 894
 895         .align  4
 896         .globl  sys_pipe
 897         .ent    sys_pipe
 898 sys_pipe:
 899         lda     $sp, -16($sp)
 900         stq     $26, 0($sp)
 901         .prologue 0
 902
 903         lda     $16, 8($sp)
 904         jsr     $26, do_pipe
 905
 906         ldq     $26, 0($sp)
 907         bne     $0, 1f
 908
 909         /* The return values are in $0 and $20.  */
 910         ldl     $1, 12($sp)
 911         ldl     $0, 8($sp)
 912
 913         stq     $1, 80+16($sp)
 914 1:      lda     $sp, 16($sp)
 915         ret
 916 .end sys_pipe
 917
 918         .align  4
 919         .globl  sys_ptrace
 920         .ent    sys_ptrace
 921 sys_ptrace:
 922         .prologue 0
 923         mov     $sp, $20
 924         jmp     $31, do_sys_ptrace
 925 .end sys_ptrace
 926
 927         .align  4
 928         .globl  sys_execve
 929         .ent    sys_execve
 930 sys_execve:
 931         .prologue 0
 932         mov     $sp, $19
 933         jmp     $31, do_sys_execve
 934 .end sys_execve
 935
 936         .align  4
 937         .globl  osf_sigprocmask
 938         .ent    osf_sigprocmask
 939 osf_sigprocmask:
 940         .prologue 0
 941         mov     $sp, $18
 942         jmp     $31, do_osf_sigprocmask
 943 .end osf_sigprocmask
 944
 945         .align  4
 946         .globl  alpha_ni_syscall
 947         .ent    alpha_ni_syscall
 948 alpha_ni_syscall:
 949         .prologue 0
 950         /* Special because it also implements overflow handling via
 951            syscall number 0.  And if you recall, zero is a special
 952            trigger for "not an error".  Store large non-zero there.  */
 953         lda     $0, -ENOSYS
 954         unop
 955         stq     $0, 0($sp)
 956         ret
 957 .end alpha_ni_syscall