arch/alpha/kernel/entry.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * arch/alpha/kernel/entry.S
   4  *
   5  * Kernel entry-points.
   6  */
   7
   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         .cfi_sections   .debug_frame
  17
  18 /* Stack offsets.  */
  19 #define SP_OFF                  184
  20 #define SWITCH_STACK_SIZE       320
  21
  22 .macro  CFI_START_OSF_FRAME     func
  23         .align  4
  24         .globl  \func
  25         .type   \func,@function
  26 \func:
  27         .cfi_startproc simple
  28         .cfi_return_column 64
  29         .cfi_def_cfa    $sp, 48
  30         .cfi_rel_offset 64, 8
  31         .cfi_rel_offset $gp, 16
  32         .cfi_rel_offset $16, 24
  33         .cfi_rel_offset $17, 32
  34         .cfi_rel_offset $18, 40
  35 .endm
  36
  37 .macro  CFI_END_OSF_FRAME       func
  38         .cfi_endproc
  39         .size   \func, . - \func
  40 .endm
  41
  42 /*
  43  * This defines the normal kernel pt-regs layout.
  44  *
  45  * regs 9-15 preserved by C code
  46  * regs 16-18 saved by PAL-code
  47  * regs 29-30 saved and set up by PAL-code
  48  * JRP - Save regs 16-18 in a special area of the stack, so that
  49  * the palcode-provided values are available to the signal handler.
  50  */
  51
  52 .macro  SAVE_ALL
  53         subq    $sp, SP_OFF, $sp
  54         .cfi_adjust_cfa_offset  SP_OFF
  55         stq     $0, 0($sp)
  56         stq     $1, 8($sp)
  57         stq     $2, 16($sp)
  58         stq     $3, 24($sp)
  59         stq     $4, 32($sp)
  60         stq     $28, 144($sp)
  61         .cfi_rel_offset $0, 0
  62         .cfi_rel_offset $1, 8
  63         .cfi_rel_offset $2, 16
  64         .cfi_rel_offset $3, 24
  65         .cfi_rel_offset $4, 32
  66         .cfi_rel_offset $28, 144
  67         lda     $2, alpha_mv
  68         stq     $5, 40($sp)
  69         stq     $6, 48($sp)
  70         stq     $7, 56($sp)
  71         stq     $8, 64($sp)
  72         stq     $19, 72($sp)
  73         stq     $20, 80($sp)
  74         stq     $21, 88($sp)
  75         ldq     $2, HAE_CACHE($2)
  76         stq     $22, 96($sp)
  77         stq     $23, 104($sp)
  78         stq     $24, 112($sp)
  79         stq     $25, 120($sp)
  80         stq     $26, 128($sp)
  81         stq     $27, 136($sp)
  82         stq     $2, 152($sp)
  83         stq     $16, 160($sp)
  84         stq     $17, 168($sp)
  85         stq     $18, 176($sp)
  86         .cfi_rel_offset $5, 40
  87         .cfi_rel_offset $6, 48
  88         .cfi_rel_offset $7, 56
  89         .cfi_rel_offset $8, 64
  90         .cfi_rel_offset $19, 72
  91         .cfi_rel_offset $20, 80
  92         .cfi_rel_offset $21, 88
  93         .cfi_rel_offset $22, 96
  94         .cfi_rel_offset $23, 104
  95         .cfi_rel_offset $24, 112
  96         .cfi_rel_offset $25, 120
  97         .cfi_rel_offset $26, 128
  98         .cfi_rel_offset $27, 136
  99 .endm
 100
 101 .macro  RESTORE_ALL
 102         lda     $19, alpha_mv
 103         ldq     $0, 0($sp)
 104         ldq     $1, 8($sp)
 105         ldq     $2, 16($sp)
 106         ldq     $3, 24($sp)
 107         ldq     $21, 152($sp)
 108         ldq     $20, HAE_CACHE($19)
 109         ldq     $4, 32($sp)
 110         ldq     $5, 40($sp)
 111         ldq     $6, 48($sp)
 112         ldq     $7, 56($sp)
 113         subq    $20, $21, $20
 114         ldq     $8, 64($sp)
 115         beq     $20, 99f
 116         ldq     $20, HAE_REG($19)
 117         stq     $21, HAE_CACHE($19)
 118         stq     $21, 0($20)
 119 99:     ldq     $19, 72($sp)
 120         ldq     $20, 80($sp)
 121         ldq     $21, 88($sp)
 122         ldq     $22, 96($sp)
 123         ldq     $23, 104($sp)
 124         ldq     $24, 112($sp)
 125         ldq     $25, 120($sp)
 126         ldq     $26, 128($sp)
 127         ldq     $27, 136($sp)
 128         ldq     $28, 144($sp)
 129         addq    $sp, SP_OFF, $sp
 130         .cfi_restore    $0
 131         .cfi_restore    $1
 132         .cfi_restore    $2
 133         .cfi_restore    $3
 134         .cfi_restore    $4
 135         .cfi_restore    $5
 136         .cfi_restore    $6
 137         .cfi_restore    $7
 138         .cfi_restore    $8
 139         .cfi_restore    $19
 140         .cfi_restore    $20
 141         .cfi_restore    $21
 142         .cfi_restore    $22
 143         .cfi_restore    $23
 144         .cfi_restore    $24
 145         .cfi_restore    $25
 146         .cfi_restore    $26
 147         .cfi_restore    $27
 148         .cfi_restore    $28
 149         .cfi_adjust_cfa_offset  -SP_OFF
 150 .endm
 151
 152 .macro  DO_SWITCH_STACK
 153         bsr     $1, do_switch_stack
 154         .cfi_adjust_cfa_offset  SWITCH_STACK_SIZE
 155         .cfi_rel_offset $9, 0
 156         .cfi_rel_offset $10, 8
 157         .cfi_rel_offset $11, 16
 158         .cfi_rel_offset $12, 24
 159         .cfi_rel_offset $13, 32
 160         .cfi_rel_offset $14, 40
 161         .cfi_rel_offset $15, 48
 162         /* We don't really care about the FP registers for debugging.  */
 163 .endm
 164
 165 .macro  UNDO_SWITCH_STACK
 166         bsr     $1, undo_switch_stack
 167         .cfi_restore    $9
 168         .cfi_restore    $10
 169         .cfi_restore    $11
 170         .cfi_restore    $12
 171         .cfi_restore    $13
 172         .cfi_restore    $14
 173         .cfi_restore    $15
 174         .cfi_adjust_cfa_offset  -SWITCH_STACK_SIZE
 175 .endm
 176
 177 /*
 178  * Non-syscall kernel entry points.
 179  */
 180
 181 CFI_START_OSF_FRAME entInt
 182         SAVE_ALL
 183         lda     $8, 0x3fff
 184         lda     $26, ret_from_sys_call
 185         bic     $sp, $8, $8
 186         mov     $sp, $19
 187         jsr     $31, do_entInt
 188 CFI_END_OSF_FRAME entInt
 189
 190 CFI_START_OSF_FRAME entArith
 191         SAVE_ALL
 192         lda     $8, 0x3fff
 193         lda     $26, ret_from_sys_call
 194         bic     $sp, $8, $8
 195         mov     $sp, $18
 196         jsr     $31, do_entArith
 197 CFI_END_OSF_FRAME entArith
 198
 199 CFI_START_OSF_FRAME entMM
 200         SAVE_ALL
 201 /* save $9 - $15 so the inline exception code can manipulate them.  */
 202         subq    $sp, 56, $sp
 203         .cfi_adjust_cfa_offset  56
 204         stq     $9, 0($sp)
 205         stq     $10, 8($sp)
 206         stq     $11, 16($sp)
 207         stq     $12, 24($sp)
 208         stq     $13, 32($sp)
 209         stq     $14, 40($sp)
 210         stq     $15, 48($sp)
 211         .cfi_rel_offset $9, 0
 212         .cfi_rel_offset $10, 8
 213         .cfi_rel_offset $11, 16
 214         .cfi_rel_offset $12, 24
 215         .cfi_rel_offset $13, 32
 216         .cfi_rel_offset $14, 40
 217         .cfi_rel_offset $15, 48
 218         addq    $sp, 56, $19
 219 /* handle the fault */
 220         lda     $8, 0x3fff
 221         bic     $sp, $8, $8
 222         jsr     $26, do_page_fault
 223 /* reload the registers after the exception code played.  */
 224         ldq     $9, 0($sp)
 225         ldq     $10, 8($sp)
 226         ldq     $11, 16($sp)
 227         ldq     $12, 24($sp)
 228         ldq     $13, 32($sp)
 229         ldq     $14, 40($sp)
 230         ldq     $15, 48($sp)
 231         addq    $sp, 56, $sp
 232         .cfi_restore    $9
 233         .cfi_restore    $10
 234         .cfi_restore    $11
 235         .cfi_restore    $12
 236         .cfi_restore    $13
 237         .cfi_restore    $14
 238         .cfi_restore    $15
 239         .cfi_adjust_cfa_offset  -56
 240 /* finish up the syscall as normal.  */
 241         br      ret_from_sys_call
 242 CFI_END_OSF_FRAME entMM
 243
 244 CFI_START_OSF_FRAME entIF
 245         SAVE_ALL
 246         lda     $8, 0x3fff
 247         lda     $26, ret_from_sys_call
 248         bic     $sp, $8, $8
 249         mov     $sp, $17
 250         jsr     $31, do_entIF
 251 CFI_END_OSF_FRAME entIF
 252
 253 CFI_START_OSF_FRAME entUna
 254         lda     $sp, -256($sp)
 255         .cfi_adjust_cfa_offset  256
 256         stq     $0, 0($sp)
 257         .cfi_rel_offset $0, 0
 258         .cfi_remember_state
 259         ldq     $0, 256($sp)    /* get PS */
 260         stq     $1, 8($sp)
 261         stq     $2, 16($sp)
 262         stq     $3, 24($sp)
 263         and     $0, 8, $0               /* user mode? */
 264         stq     $4, 32($sp)
 265         bne     $0, entUnaUser  /* yup -> do user-level unaligned fault */
 266         stq     $5, 40($sp)
 267         stq     $6, 48($sp)
 268         stq     $7, 56($sp)
 269         stq     $8, 64($sp)
 270         stq     $9, 72($sp)
 271         stq     $10, 80($sp)
 272         stq     $11, 88($sp)
 273         stq     $12, 96($sp)
 274         stq     $13, 104($sp)
 275         stq     $14, 112($sp)
 276         stq     $15, 120($sp)
 277         /* 16-18 PAL-saved */
 278         stq     $19, 152($sp)
 279         stq     $20, 160($sp)
 280         stq     $21, 168($sp)
 281         stq     $22, 176($sp)
 282         stq     $23, 184($sp)
 283         stq     $24, 192($sp)
 284         stq     $25, 200($sp)
 285         stq     $26, 208($sp)
 286         stq     $27, 216($sp)
 287         stq     $28, 224($sp)
 288         mov     $sp, $19
 289         stq     $gp, 232($sp)
 290         .cfi_rel_offset $1, 1*8
 291         .cfi_rel_offset $2, 2*8
 292         .cfi_rel_offset $3, 3*8
 293         .cfi_rel_offset $4, 4*8
 294         .cfi_rel_offset $5, 5*8
 295         .cfi_rel_offset $6, 6*8
 296         .cfi_rel_offset $7, 7*8
 297         .cfi_rel_offset $8, 8*8
 298         .cfi_rel_offset $9, 9*8
 299         .cfi_rel_offset $10, 10*8
 300         .cfi_rel_offset $11, 11*8
 301         .cfi_rel_offset $12, 12*8
 302         .cfi_rel_offset $13, 13*8
 303         .cfi_rel_offset $14, 14*8
 304         .cfi_rel_offset $15, 15*8
 305         .cfi_rel_offset $19, 19*8
 306         .cfi_rel_offset $20, 20*8
 307         .cfi_rel_offset $21, 21*8
 308         .cfi_rel_offset $22, 22*8
 309         .cfi_rel_offset $23, 23*8
 310         .cfi_rel_offset $24, 24*8
 311         .cfi_rel_offset $25, 25*8
 312         .cfi_rel_offset $26, 26*8
 313         .cfi_rel_offset $27, 27*8
 314         .cfi_rel_offset $28, 28*8
 315         .cfi_rel_offset $29, 29*8
 316         lda     $8, 0x3fff
 317         stq     $31, 248($sp)
 318         bic     $sp, $8, $8
 319         jsr     $26, do_entUna
 320         ldq     $0, 0($sp)
 321         ldq     $1, 8($sp)
 322         ldq     $2, 16($sp)
 323         ldq     $3, 24($sp)
 324         ldq     $4, 32($sp)
 325         ldq     $5, 40($sp)
 326         ldq     $6, 48($sp)
 327         ldq     $7, 56($sp)
 328         ldq     $8, 64($sp)
 329         ldq     $9, 72($sp)
 330         ldq     $10, 80($sp)
 331         ldq     $11, 88($sp)
 332         ldq     $12, 96($sp)
 333         ldq     $13, 104($sp)
 334         ldq     $14, 112($sp)
 335         ldq     $15, 120($sp)
 336         /* 16-18 PAL-saved */
 337         ldq     $19, 152($sp)
 338         ldq     $20, 160($sp)
 339         ldq     $21, 168($sp)
 340         ldq     $22, 176($sp)
 341         ldq     $23, 184($sp)
 342         ldq     $24, 192($sp)
 343         ldq     $25, 200($sp)
 344         ldq     $26, 208($sp)
 345         ldq     $27, 216($sp)
 346         ldq     $28, 224($sp)
 347         ldq     $gp, 232($sp)
 348         lda     $sp, 256($sp)
 349         .cfi_restore    $1
 350         .cfi_restore    $2
 351         .cfi_restore    $3
 352         .cfi_restore    $4
 353         .cfi_restore    $5
 354         .cfi_restore    $6
 355         .cfi_restore    $7
 356         .cfi_restore    $8
 357         .cfi_restore    $9
 358         .cfi_restore    $10
 359         .cfi_restore    $11
 360         .cfi_restore    $12
 361         .cfi_restore    $13
 362         .cfi_restore    $14
 363         .cfi_restore    $15
 364         .cfi_restore    $19
 365         .cfi_restore    $20
 366         .cfi_restore    $21
 367         .cfi_restore    $22
 368         .cfi_restore    $23
 369         .cfi_restore    $24
 370         .cfi_restore    $25
 371         .cfi_restore    $26
 372         .cfi_restore    $27
 373         .cfi_restore    $28
 374         .cfi_restore    $29
 375         .cfi_adjust_cfa_offset  -256
 376         call_pal PAL_rti
 377
 378         .align  4
 379 entUnaUser:
 380         .cfi_restore_state
 381         ldq     $0, 0($sp)      /* restore original $0 */
 382         lda     $sp, 256($sp)   /* pop entUna's stack frame */
 383         .cfi_restore    $0
 384         .cfi_adjust_cfa_offset  -256
 385         SAVE_ALL                /* setup normal kernel stack */
 386         lda     $sp, -56($sp)
 387         .cfi_adjust_cfa_offset  56
 388         stq     $9, 0($sp)
 389         stq     $10, 8($sp)
 390         stq     $11, 16($sp)
 391         stq     $12, 24($sp)
 392         stq     $13, 32($sp)
 393         stq     $14, 40($sp)
 394         stq     $15, 48($sp)
 395         .cfi_rel_offset $9, 0
 396         .cfi_rel_offset $10, 8
 397         .cfi_rel_offset $11, 16
 398         .cfi_rel_offset $12, 24
 399         .cfi_rel_offset $13, 32
 400         .cfi_rel_offset $14, 40
 401         .cfi_rel_offset $15, 48
 402         lda     $8, 0x3fff
 403         addq    $sp, 56, $19
 404         bic     $sp, $8, $8
 405         jsr     $26, do_entUnaUser
 406         ldq     $9, 0($sp)
 407         ldq     $10, 8($sp)
 408         ldq     $11, 16($sp)
 409         ldq     $12, 24($sp)
 410         ldq     $13, 32($sp)
 411         ldq     $14, 40($sp)
 412         ldq     $15, 48($sp)
 413         lda     $sp, 56($sp)
 414         .cfi_restore    $9
 415         .cfi_restore    $10
 416         .cfi_restore    $11
 417         .cfi_restore    $12
 418         .cfi_restore    $13
 419         .cfi_restore    $14
 420         .cfi_restore    $15
 421         .cfi_adjust_cfa_offset  -56
 422         br      ret_from_sys_call
 423 CFI_END_OSF_FRAME entUna
 424
 425 CFI_START_OSF_FRAME entDbg
 426         SAVE_ALL
 427         lda     $8, 0x3fff
 428         lda     $26, ret_from_sys_call
 429         bic     $sp, $8, $8
 430         mov     $sp, $16
 431         jsr     $31, do_entDbg
 432 CFI_END_OSF_FRAME entDbg
 433 \f
 434 /*
 435  * The system call entry point is special.  Most importantly, it looks
 436  * like a function call to userspace as far as clobbered registers.  We
 437  * do preserve the argument registers (for syscall restarts) and $26
 438  * (for leaf syscall functions).
 439  *
 440  * So much for theory.  We don't take advantage of this yet.
 441  *
 442  * Note that a0-a2 are not saved by PALcode as with the other entry points.
 443  */
 444
 445         .align  4
 446         .globl  entSys
 447         .type   entSys, @function
 448         .cfi_startproc simple
 449         .cfi_return_column 64
 450         .cfi_def_cfa    $sp, 48
 451         .cfi_rel_offset 64, 8
 452         .cfi_rel_offset $gp, 16
 453 entSys:
 454         SAVE_ALL
 455         lda     $8, 0x3fff
 456         bic     $sp, $8, $8
 457         lda     $4, NR_SYSCALLS($31)
 458         stq     $16, SP_OFF+24($sp)
 459         lda     $5, sys_call_table
 460         lda     $27, sys_ni_syscall
 461         cmpult  $0, $4, $4
 462         ldl     $3, TI_FLAGS($8)
 463         stq     $17, SP_OFF+32($sp)
 464         s8addq  $0, $5, $5
 465         stq     $18, SP_OFF+40($sp)
 466         .cfi_rel_offset $16, SP_OFF+24
 467         .cfi_rel_offset $17, SP_OFF+32
 468         .cfi_rel_offset $18, SP_OFF+40
 469 #ifdef CONFIG_AUDITSYSCALL
 470         lda     $6, _TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT
 471         and     $3, $6, $3
 472 #endif
 473         bne     $3, strace
 474         beq     $4, 1f
 475         ldq     $27, 0($5)
 476 1:      jsr     $26, ($27), alpha_ni_syscall
 477         ldgp    $gp, 0($26)
 478         blt     $0, $syscall_error      /* the call failed */
 479         stq     $0, 0($sp)
 480         stq     $31, 72($sp)            /* a3=0 => no error */
 481
 482         .align  4
 483         .globl  ret_from_sys_call
 484 ret_from_sys_call:
 485         cmovne  $26, 0, $18             /* $18 = 0 => non-restartable */
 486         ldq     $0, SP_OFF($sp)
 487         and     $0, 8, $0
 488         beq     $0, ret_to_kernel
 489 ret_to_user:
 490         /* Make sure need_resched and sigpending don't change between
 491                 sampling and the rti.  */
 492         lda     $16, 7
 493         call_pal PAL_swpipl
 494         ldl     $17, TI_FLAGS($8)
 495         and     $17, _TIF_WORK_MASK, $2
 496         bne     $2, work_pending
 497 restore_all:
 498         .cfi_remember_state
 499         RESTORE_ALL
 500         call_pal PAL_rti
 501
 502 ret_to_kernel:
 503         .cfi_restore_state
 504         lda     $16, 7
 505         call_pal PAL_swpipl
 506         br restore_all
 507
 508         .align 3
 509 $syscall_error:
 510         /*
 511          * Some system calls (e.g., ptrace) can return arbitrary
 512          * values which might normally be mistaken as error numbers.
 513          * Those functions must zero $0 (v0) directly in the stack
 514          * frame to indicate that a negative return value wasn't an
 515          * error number..
 516          */
 517         ldq     $18, 0($sp)     /* old syscall nr (zero if success) */
 518         beq     $18, $ret_success
 519
 520         ldq     $19, 72($sp)    /* .. and this a3 */
 521         subq    $31, $0, $0     /* with error in v0 */
 522         addq    $31, 1, $1      /* set a3 for errno return */
 523         stq     $0, 0($sp)
 524         mov     $31, $26        /* tell "ret_from_sys_call" we can restart */
 525         stq     $1, 72($sp)     /* a3 for return */
 526         br      ret_from_sys_call
 527
 528 $ret_success:
 529         stq     $0, 0($sp)
 530         stq     $31, 72($sp)    /* a3=0 => no error */
 531         br      ret_from_sys_call
 532
 533 /*
 534  * Do all cleanup when returning from all interrupts and system calls.
 535  *
 536  * Arguments:
 537  *       $8: current.
 538  *      $17: TI_FLAGS.
 539  *      $18: The old syscall number, or zero if this is not a return
 540  *           from a syscall that errored and is possibly restartable.
 541  *      $19: The old a3 value
 542  */
 543
 544         .align  4
 545         .type   work_pending, @function
 546 work_pending:
 547         and     $17, _TIF_NOTIFY_RESUME | _TIF_SIGPENDING, $2
 548         bne     $2, $work_notifysig
 549
 550 $work_resched:
 551         /*
 552          * We can get here only if we returned from syscall without SIGPENDING
 553          * or got through work_notifysig already.  Either case means no syscall
 554          * restarts for us, so let $18 and $19 burn.
 555          */
 556         jsr     $26, schedule
 557         mov     0, $18
 558         br      ret_to_user
 559
 560 $work_notifysig:
 561         mov     $sp, $16
 562         DO_SWITCH_STACK
 563         jsr     $26, do_work_pending
 564         UNDO_SWITCH_STACK
 565         br      restore_all
 566
 567 /*
 568  * PTRACE syscall handler
 569  */
 570
 571         .align  4
 572         .type   strace, @function
 573 strace:
 574         /* set up signal stack, call syscall_trace */
 575         DO_SWITCH_STACK
 576         jsr     $26, syscall_trace_enter /* returns the syscall number */
 577         UNDO_SWITCH_STACK
 578
 579         /* get the arguments back.. */
 580         ldq     $16, SP_OFF+24($sp)
 581         ldq     $17, SP_OFF+32($sp)
 582         ldq     $18, SP_OFF+40($sp)
 583         ldq     $19, 72($sp)
 584         ldq     $20, 80($sp)
 585         ldq     $21, 88($sp)
 586
 587         /* get the system call pointer.. */
 588         lda     $1, NR_SYSCALLS($31)
 589         lda     $2, sys_call_table
 590         lda     $27, alpha_ni_syscall
 591         cmpult  $0, $1, $1
 592         s8addq  $0, $2, $2
 593         beq     $1, 1f
 594         ldq     $27, 0($2)
 595 1:      jsr     $26, ($27), sys_gettimeofday
 596 ret_from_straced:
 597         ldgp    $gp, 0($26)
 598
 599         /* check return.. */
 600         blt     $0, $strace_error       /* the call failed */
 601         stq     $31, 72($sp)            /* a3=0 => no error */
 602 $strace_success:
 603         stq     $0, 0($sp)              /* save return value */
 604
 605         DO_SWITCH_STACK
 606         jsr     $26, syscall_trace_leave
 607         UNDO_SWITCH_STACK
 608         br      $31, ret_from_sys_call
 609
 610         .align  3
 611 $strace_error:
 612         ldq     $18, 0($sp)     /* old syscall nr (zero if success) */
 613         beq     $18, $strace_success
 614         ldq     $19, 72($sp)    /* .. and this a3 */
 615
 616         subq    $31, $0, $0     /* with error in v0 */
 617         addq    $31, 1, $1      /* set a3 for errno return */
 618         stq     $0, 0($sp)
 619         stq     $1, 72($sp)     /* a3 for return */
 620
 621         DO_SWITCH_STACK
 622         mov     $18, $9         /* save old syscall number */
 623         mov     $19, $10        /* save old a3 */
 624         jsr     $26, syscall_trace_leave
 625         mov     $9, $18
 626         mov     $10, $19
 627         UNDO_SWITCH_STACK
 628
 629         mov     $31, $26        /* tell "ret_from_sys_call" we can restart */
 630         br      ret_from_sys_call
 631 CFI_END_OSF_FRAME entSys
 632 \f
 633 /*
 634  * Save and restore the switch stack -- aka the balance of the user context.
 635  */
 636
 637         .align  4
 638         .type   do_switch_stack, @function
 639         .cfi_startproc simple
 640         .cfi_return_column 64
 641         .cfi_def_cfa $sp, 0
 642         .cfi_register 64, $1
 643 do_switch_stack:
 644         lda     $sp, -SWITCH_STACK_SIZE($sp)
 645         .cfi_adjust_cfa_offset  SWITCH_STACK_SIZE
 646         stq     $9, 0($sp)
 647         stq     $10, 8($sp)
 648         stq     $11, 16($sp)
 649         stq     $12, 24($sp)
 650         stq     $13, 32($sp)
 651         stq     $14, 40($sp)
 652         stq     $15, 48($sp)
 653         stq     $26, 56($sp)
 654         stt     $f0, 64($sp)
 655         stt     $f1, 72($sp)
 656         stt     $f2, 80($sp)
 657         stt     $f3, 88($sp)
 658         stt     $f4, 96($sp)
 659         stt     $f5, 104($sp)
 660         stt     $f6, 112($sp)
 661         stt     $f7, 120($sp)
 662         stt     $f8, 128($sp)
 663         stt     $f9, 136($sp)
 664         stt     $f10, 144($sp)
 665         stt     $f11, 152($sp)
 666         stt     $f12, 160($sp)
 667         stt     $f13, 168($sp)
 668         stt     $f14, 176($sp)
 669         stt     $f15, 184($sp)
 670         stt     $f16, 192($sp)
 671         stt     $f17, 200($sp)
 672         stt     $f18, 208($sp)
 673         stt     $f19, 216($sp)
 674         stt     $f20, 224($sp)
 675         stt     $f21, 232($sp)
 676         stt     $f22, 240($sp)
 677         stt     $f23, 248($sp)
 678         stt     $f24, 256($sp)
 679         stt     $f25, 264($sp)
 680         stt     $f26, 272($sp)
 681         stt     $f27, 280($sp)
 682         mf_fpcr $f0             # get fpcr
 683         stt     $f28, 288($sp)
 684         stt     $f29, 296($sp)
 685         stt     $f30, 304($sp)
 686         stt     $f0, 312($sp)   # save fpcr in slot of $f31
 687         ldt     $f0, 64($sp)    # dont let "do_switch_stack" change fp state.
 688         ret     $31, ($1), 1
 689         .cfi_endproc
 690         .size   do_switch_stack, .-do_switch_stack
 691
 692         .align  4
 693         .type   undo_switch_stack, @function
 694         .cfi_startproc simple
 695         .cfi_def_cfa $sp, 0
 696         .cfi_register 64, $1
 697 undo_switch_stack:
 698         ldq     $9, 0($sp)
 699         ldq     $10, 8($sp)
 700         ldq     $11, 16($sp)
 701         ldq     $12, 24($sp)
 702         ldq     $13, 32($sp)
 703         ldq     $14, 40($sp)
 704         ldq     $15, 48($sp)
 705         ldq     $26, 56($sp)
 706         ldt     $f30, 312($sp)  # get saved fpcr
 707         ldt     $f0, 64($sp)
 708         ldt     $f1, 72($sp)
 709         ldt     $f2, 80($sp)
 710         ldt     $f3, 88($sp)
 711         mt_fpcr $f30            # install saved fpcr
 712         ldt     $f4, 96($sp)
 713         ldt     $f5, 104($sp)
 714         ldt     $f6, 112($sp)
 715         ldt     $f7, 120($sp)
 716         ldt     $f8, 128($sp)
 717         ldt     $f9, 136($sp)
 718         ldt     $f10, 144($sp)
 719         ldt     $f11, 152($sp)
 720         ldt     $f12, 160($sp)
 721         ldt     $f13, 168($sp)
 722         ldt     $f14, 176($sp)
 723         ldt     $f15, 184($sp)
 724         ldt     $f16, 192($sp)
 725         ldt     $f17, 200($sp)
 726         ldt     $f18, 208($sp)
 727         ldt     $f19, 216($sp)
 728         ldt     $f20, 224($sp)
 729         ldt     $f21, 232($sp)
 730         ldt     $f22, 240($sp)
 731         ldt     $f23, 248($sp)
 732         ldt     $f24, 256($sp)
 733         ldt     $f25, 264($sp)
 734         ldt     $f26, 272($sp)
 735         ldt     $f27, 280($sp)
 736         ldt     $f28, 288($sp)
 737         ldt     $f29, 296($sp)
 738         ldt     $f30, 304($sp)
 739         lda     $sp, SWITCH_STACK_SIZE($sp)
 740         ret     $31, ($1), 1
 741         .cfi_endproc
 742         .size   undo_switch_stack, .-undo_switch_stack
 743 \f
 744 /*
 745  * The meat of the context switch code.
 746  */
 747
 748         .align  4
 749         .globl  alpha_switch_to
 750         .type   alpha_switch_to, @function
 751         .cfi_startproc
 752 alpha_switch_to:
 753         DO_SWITCH_STACK
 754         call_pal PAL_swpctx
 755         lda     $8, 0x3fff
 756         UNDO_SWITCH_STACK
 757         bic     $sp, $8, $8
 758         mov     $17, $0
 759         ret
 760         .cfi_endproc
 761         .size   alpha_switch_to, .-alpha_switch_to
 762
 763 /*
 764  * New processes begin life here.
 765  */
 766
 767         .globl  ret_from_fork
 768         .align  4
 769         .ent    ret_from_fork
 770 ret_from_fork:
 771         lda     $26, ret_from_sys_call
 772         mov     $17, $16
 773         jmp     $31, schedule_tail
 774 .end ret_from_fork
 775
 776 /*
 777  * ... and new kernel threads - here
 778  */
 779         .align 4
 780         .globl  ret_from_kernel_thread
 781         .ent    ret_from_kernel_thread
 782 ret_from_kernel_thread:
 783         mov     $17, $16
 784         jsr     $26, schedule_tail
 785         mov     $9, $27
 786         mov     $10, $16
 787         jsr     $26, ($9)
 788         mov     $31, $19                /* to disable syscall restarts */
 789         br      $31, ret_to_user
 790 .end ret_from_kernel_thread
 791
 792 \f
 793 /*
 794  * Special system calls.  Most of these are special in that they either
 795  * have to play switch_stack games or in some way use the pt_regs struct.
 796  */
 797
 798 .macro  fork_like name
 799         .align  4
 800         .globl  alpha_\name
 801         .ent    alpha_\name
 802 alpha_\name:
 803         .prologue 0
 804         bsr     $1, do_switch_stack
 805         jsr     $26, sys_\name
 806         ldq     $26, 56($sp)
 807         lda     $sp, SWITCH_STACK_SIZE($sp)
 808         ret
 809 .end    alpha_\name
 810 .endm
 811
 812 fork_like fork
 813 fork_like vfork
 814 fork_like clone
 815
 816         .align  4
 817         .globl  sys_sigreturn
 818         .ent    sys_sigreturn
 819 sys_sigreturn:
 820         .prologue 0
 821         lda     $9, ret_from_straced
 822         cmpult  $26, $9, $9
 823         lda     $sp, -SWITCH_STACK_SIZE($sp)
 824         jsr     $26, do_sigreturn
 825         bne     $9, 1f
 826         jsr     $26, syscall_trace_leave
 827 1:      br      $1, undo_switch_stack
 828         br      ret_from_sys_call
 829 .end sys_sigreturn
 830
 831         .align  4
 832         .globl  sys_rt_sigreturn
 833         .ent    sys_rt_sigreturn
 834 sys_rt_sigreturn:
 835         .prologue 0
 836         lda     $9, ret_from_straced
 837         cmpult  $26, $9, $9
 838         lda     $sp, -SWITCH_STACK_SIZE($sp)
 839         jsr     $26, do_rt_sigreturn
 840         bne     $9, 1f
 841         jsr     $26, syscall_trace_leave
 842 1:      br      $1, undo_switch_stack
 843         br      ret_from_sys_call
 844 .end sys_rt_sigreturn
 845
 846         .align  4
 847         .globl  alpha_ni_syscall
 848         .ent    alpha_ni_syscall
 849 alpha_ni_syscall:
 850         .prologue 0
 851         /* Special because it also implements overflow handling via
 852            syscall number 0.  And if you recall, zero is a special
 853            trigger for "not an error".  Store large non-zero there.  */
 854         lda     $0, -ENOSYS
 855         unop
 856         stq     $0, 0($sp)
 857         ret
 858 .end alpha_ni_syscall