arch/cris/arch-v10/kernel/entry.S

   1 /*
   2  *  linux/arch/cris/entry.S
   3  *
   4  *  Copyright (C) 2000, 2001, 2002 Axis Communications AB
   5  *
   6  *  Authors:    Bjorn Wesen (bjornw@axis.com)
   7  */
   8
   9 /*
  10  * entry.S contains the system-call and fault low-level handling routines.
  11  *
  12  * NOTE: This code handles signal-recognition, which happens every time
  13  * after a timer-interrupt and after each system call.
  14  *
  15  * Stack layout in 'ret_from_system_call':
  16  *      ptrace needs to have all regs on the stack.
  17  *      if the order here is changed, it needs to be
  18  *      updated in fork.c:copy_process, signal.c:do_signal,
  19  *      ptrace.c and ptrace.h
  20  *
  21  */
  22
  23 #include <linux/linkage.h>
  24 #include <linux/sys.h>
  25 #include <asm/unistd.h>
  26 #include <arch/sv_addr_ag.h>
  27 #include <asm/errno.h>
  28 #include <asm/thread_info.h>
  29 #include <asm/asm-offsets.h>
  30 #include <asm/page.h>
  31 #include <asm/pgtable.h>
  32
  33         ;; functions exported from this file
  34
  35         .globl system_call
  36         .globl ret_from_intr
  37         .globl ret_from_fork
  38         .globl ret_from_kernel_thread
  39         .globl resume
  40         .globl multiple_interrupt
  41         .globl hwbreakpoint
  42         .globl IRQ1_interrupt
  43         .globl spurious_interrupt
  44         .globl hw_bp_trigs
  45         .globl mmu_bus_fault
  46         .globl do_sigtrap
  47         .globl gdb_handle_breakpoint
  48         .globl sys_call_table
  49
  50         ;; below are various parts of system_call which are not in the fast-path
  51
  52 #ifdef CONFIG_PREEMPT
  53         ; Check if preemptive kernel scheduling should be done
  54 _resume_kernel:
  55         di
  56         ; Load current task struct
  57         movs.w  -8192, $r0      ;  THREAD_SIZE = 8192
  58         and.d   $sp, $r0
  59         move.d  [$r0+TI_preempt_count], $r10    ;  Preemption disabled?
  60         bne     _Rexit
  61         nop
  62 _need_resched:
  63         move.d  [$r0+TI_flags], $r10
  64         btstq   TIF_NEED_RESCHED, $r10  ; Check if need_resched is set
  65         bpl     _Rexit
  66         nop
  67         ; Ok, lets's do some preemptive kernel scheduling
  68         jsr     preempt_schedule_irq
  69         ; Load new task struct
  70         movs.w  -8192, $r0      ;  THREAD_SIZE = 8192
  71         and.d   $sp, $r0
  72         ; One more time (with new task)
  73         ba      _need_resched
  74         nop
  75 #else
  76 #define _resume_kernel _Rexit
  77 #endif
  78
  79         ; Called at exit from fork. schedule_tail must be called to drop
  80         ; spinlock if CONFIG_PREEMPT
  81 ret_from_fork:
  82         jsr schedule_tail
  83         ba  ret_from_sys_call
  84         nop
  85
  86 ret_from_kernel_thread:
  87         jsr schedule_tail
  88         move.d  $r2, $r10       ; argument is here
  89         jsr     $r1             ; call the payload
  90         moveq   0, $r9          ; no syscall restarts, TYVM...
  91         ba  ret_from_sys_call
  92
  93 ret_from_intr:
  94         ;; check for resched if preemptive kernel or if we're going back to user-mode
  95         ;; this test matches the user_regs(regs) macro
  96         ;; we cannot simply test $dccr, because that does not necessarily
  97         ;; reflect what mode we'll return into.
  98
  99         move.d  [$sp + PT_dccr], $r0; regs->dccr
 100         btstq   8, $r0          ; U-flag
 101         bpl     _resume_kernel
 102         ; Note that di below is in delay slot
 103
 104 _resume_userspace:
 105         di                      ; so need_resched and sigpending don't change
 106
 107         movs.w  -8192, $r0      ; THREAD_SIZE == 8192
 108         and.d   $sp, $r0
 109
 110         move.d  [$r0+TI_flags], $r10    ; current->work
 111         and.d   _TIF_WORK_MASK, $r10    ; is there any work to be done on return
 112         bne     _work_pending
 113         nop
 114         ba      _Rexit
 115         nop
 116
 117         ;; The system_call is called by a BREAK instruction, which works like
 118         ;; an interrupt call but it stores the return PC in BRP instead of IRP.
 119         ;; Since we dont really want to have two epilogues (one for system calls
 120         ;; and one for interrupts) we push the contents of BRP instead of IRP in the
 121         ;; system call prologue, to make it look like an ordinary interrupt on the
 122         ;; stackframe.
 123         ;;
 124         ;; Since we can't have system calls inside interrupts, it should not matter
 125         ;; that we don't stack IRP.
 126         ;;
 127         ;; In r9 we have the wanted syscall number. Arguments come in r10,r11,r12,r13,mof,srp
 128         ;;
 129         ;; This function looks on the _surface_ like spaghetti programming, but it's
 130         ;; really designed so that the fast-path does not force cache-loading of non-used
 131         ;; instructions. Only the non-common cases cause the outlined code to run..
 132
 133 system_call:
 134         ;; stack-frame similar to the irq heads, which is reversed in ret_from_sys_call
 135         move    $brp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
 136         push    $srp
 137         push    $dccr
 138         push    $mof
 139         subq    14*4, $sp               ; make room for r0-r13
 140         movem   $r13, [$sp]     ; push r0-r13
 141         push    $r10            ; push orig_r10
 142         clear.d [$sp=$sp-4]     ; frametype == 0, normal stackframe
 143
 144         movs.w  -ENOSYS, $r0
 145         move.d  $r0, [$sp+PT_r10]       ; put the default return value in r10 in the frame
 146
 147         ;; check if this process is syscall-traced
 148
 149         movs.w  -8192, $r0      ; THREAD_SIZE == 8192
 150         and.d   $sp, $r0
 151
 152         move.d  [$r0+TI_flags], $r0
 153         btstq   TIF_SYSCALL_TRACE, $r0
 154         bmi     _syscall_trace_entry
 155         nop
 156
 157 _syscall_traced:
 158
 159         ;; check for sanity in the requested syscall number
 160
 161         cmpu.w  NR_syscalls, $r9
 162         bcc     ret_from_sys_call
 163         lslq    2, $r9          ;  multiply by 4, in the delay slot
 164
 165         ;; as a bonus 7th parameter, we give the location on the stack
 166         ;; of the register structure itself. some syscalls need this.
 167
 168         push    $sp
 169
 170         ;; the parameter carrying registers r10, r11, r12 and 13 are intact.
 171         ;; the fifth and sixth parameters (if any) was in mof and srp
 172         ;; respectively, and we need to put them on the stack.
 173
 174         push    $srp
 175         push    $mof
 176
 177         jsr     [$r9+sys_call_table]    ; actually do the system call
 178         addq    3*4, $sp                ; pop the mof, srp and regs parameters
 179         move.d  $r10, [$sp+PT_r10]      ; save the return value
 180
 181         moveq   1, $r9          ; "parameter" to ret_from_sys_call to show it was a sys call
 182
 183         ;; fall through into ret_from_sys_call to return
 184
 185 ret_from_sys_call:
 186         ;; r9 is a parameter - if >=1 we came from a syscall, if 0, from an irq
 187
 188         ;; get the current task-struct pointer (see top for defs)
 189
 190         movs.w  -8192, $r0      ; THREAD_SIZE == 8192
 191         and.d   $sp, $r0
 192
 193         di                      ; make sure need_resched and sigpending don't change
 194         move.d  [$r0+TI_flags],$r1
 195         and.d   _TIF_ALLWORK_MASK, $r1
 196         bne     _syscall_exit_work
 197         nop
 198
 199 _Rexit:
 200         ;; this epilogue MUST match the prologues in multiple_interrupt, irq.h and ptregs.h
 201         pop     $r10            ; frametype
 202         bne     _RBFexit        ; was not CRIS_FRAME_NORMAL, handle otherwise
 203         addq    4, $sp          ; skip orig_r10, in delayslot
 204         movem   [$sp+], $r13    ; registers r0-r13
 205         pop     $mof            ; multiply overflow register
 206         pop     $dccr           ; condition codes
 207         pop     $srp            ; subroutine return pointer
 208         ;; now we have a 4-word SBFS frame which we do not want to restore
 209         ;; using RBF since it was not stacked with SBFS. instead we would like to
 210         ;; just get the PC value to restart it with, and skip the rest of
 211         ;; the frame.
 212         ;; Also notice that it's important to use instructions here that
 213         ;; keep the interrupts disabled (since we've already popped DCCR)
 214         move    [$sp=$sp+16], $p8; pop the SBFS frame from the sp
 215         jmpu    [$sp-16]        ; return through the irp field in the sbfs frame
 216
 217 _RBFexit:
 218         movem   [$sp+], $r13    ; registers r0-r13, in delay slot
 219         pop     $mof            ; multiply overflow register
 220         pop     $dccr           ; condition codes
 221         pop     $srp            ; subroutine return pointer
 222         rbf     [$sp+]          ; return by popping the CPU status
 223
 224         ;; We get here after doing a syscall if extra work might need to be done
 225         ;; perform syscall exit tracing if needed
 226
 227 _syscall_exit_work:
 228         ;; $r0 contains current at this point and irq's are disabled
 229
 230         move.d  [$r0+TI_flags], $r1
 231         btstq   TIF_SYSCALL_TRACE, $r1
 232         bpl     _work_pending
 233         nop
 234
 235         ei
 236
 237         move.d  $r9, $r1        ; preserve r9
 238         jsr     do_syscall_trace
 239         move.d  $r1, $r9
 240
 241         ba      _resume_userspace
 242         nop
 243
 244 _work_pending:
 245         move.d  [$r0+TI_flags], $r1
 246         btstq   TIF_NEED_RESCHED, $r1
 247         bpl     _work_notifysig ; was neither trace nor sched, must be signal/notify
 248         nop
 249
 250 _work_resched:
 251         move.d  $r9, $r1        ; preserve r9
 252         jsr     schedule
 253         move.d  $r1, $r9
 254         di
 255
 256         move.d  [$r0+TI_flags], $r1
 257         and.d   _TIF_WORK_MASK, $r1; ignore the syscall trace counter
 258         beq     _Rexit
 259         nop
 260         btstq   TIF_NEED_RESCHED, $r1
 261         bmi     _work_resched   ; current->work.need_resched
 262         nop
 263
 264 _work_notifysig:
 265         ;; deal with pending signals and notify-resume requests
 266
 267         move.d  $r9, $r10       ; do_notify_resume syscall/irq param
 268         move.d  $sp, $r11       ; the regs param
 269         move.d  $r1, $r12       ; the thread_info_flags parameter
 270         jsr     do_notify_resume
 271
 272         ba _Rexit
 273         nop
 274
 275         ;; We get here as a sidetrack when we've entered a syscall with the
 276         ;; trace-bit set. We need to call do_syscall_trace and then continue
 277         ;; with the call.
 278
 279 _syscall_trace_entry:
 280         ;; PT_r10 in the frame contains -ENOSYS as required, at this point
 281
 282         jsr     do_syscall_trace
 283
 284         ;; now re-enter the syscall code to do the syscall itself
 285         ;; we need to restore $r9 here to contain the wanted syscall, and
 286         ;; the other parameter-bearing registers
 287
 288         move.d  [$sp+PT_r9], $r9
 289         move.d  [$sp+PT_orig_r10], $r10  ; PT_r10 is already filled with -ENOSYS.
 290         move.d  [$sp+PT_r11],      $r11
 291         move.d  [$sp+PT_r12],      $r12
 292         move.d  [$sp+PT_r13],      $r13
 293         move    [$sp+PT_mof],      $mof
 294         move    [$sp+PT_srp],      $srp
 295
 296         ba      _syscall_traced
 297         nop
 298
 299         ;; resume performs the actual task-switching, by switching stack pointers
 300         ;; input arguments: r10 = prev, r11 = next, r12 = thread offset in task struct
 301         ;; returns old current in r10
 302         ;;
 303         ;; TODO:  see the i386 version. The switch_to which calls resume in our version
 304         ;;        could really be an inline asm of this.
 305
 306 resume:
 307         push    $srp                     ; we keep the old/new PC on the stack
 308         add.d   $r12, $r10               ; r10 = current tasks tss
 309         move    $dccr, [$r10+THREAD_dccr]; save irq enable state
 310         di
 311
 312         move    $usp, [$r10+ THREAD_usp] ; save user-mode stackpointer
 313
 314         ;; See copy_thread for the reason why register R9 is saved.
 315         subq    10*4, $sp
 316         movem   $r9, [$sp]               ; save non-scratch registers and R9.
 317
 318         move.d  $sp, [$r10+THREAD_ksp]   ; save the kernel stack pointer for the old task
 319         move.d  $sp, $r10                ; return last running task in r10
 320         and.d   -8192, $r10              ; get thread_info from stackpointer
 321         move.d  [$r10+TI_task], $r10     ; get task
 322         add.d   $r12, $r11               ; find the new tasks tss
 323         move.d  [$r11+THREAD_ksp], $sp   ; switch into the new stackframe by restoring kernel sp
 324
 325         movem   [$sp+], $r9              ; restore non-scratch registers and R9.
 326
 327         move    [$r11+THREAD_usp], $usp ; restore user-mode stackpointer
 328
 329         move    [$r11+THREAD_dccr], $dccr ; restore irq enable status
 330         jump    [$sp+]                   ; restore PC
 331
 332         ;; This is the MMU bus fault handler.
 333         ;; It needs to stack the CPU status and overall is different
 334         ;; from the other interrupt handlers.
 335
 336 mmu_bus_fault:
 337         ;; For refills we try to do a quick page table lookup. If it is
 338         ;; a real fault we let the mm subsystem handle it.
 339
 340         ;; the first longword in the sbfs frame was the interrupted PC
 341         ;; which fits nicely with the "IRP" slot in pt_regs normally used to
 342         ;; contain the return address. used by Oops to print kernel errors.
 343         sbfs    [$sp=$sp-16]    ; push the internal CPU status
 344         push    $dccr
 345         di
 346         subq    2*4, $sp
 347         movem   $r1, [$sp]
 348         move.d  [R_MMU_CAUSE], $r1
 349         ;; ETRAX 100LX TR89 bugfix: if the second half of an unaligned
 350         ;; write causes a MMU-fault, it will not be restarted correctly.
 351         ;; This could happen if a write crosses a page-boundary and the
 352         ;; second page is not yet COW'ed or even loaded. The workaround
 353         ;; is to clear the unaligned bit in the CPU status record, so
 354         ;; that the CPU will rerun both the first and second halves of
 355         ;; the instruction. This will not have any sideeffects unless
 356         ;; the first half goes to any device or memory that can't be
 357         ;; written twice, and which is mapped through the MMU.
 358         ;;
 359         ;; We only need to do this for writes.
 360         btstq   8, $r1             ; Write access?
 361         bpl     1f
 362         nop
 363         move.d  [$sp+16], $r0      ; Clear unaligned bit in csrinstr
 364         and.d   ~(1<<5), $r0
 365         move.d  $r0, [$sp+16]
 366 1:      btstq   12, $r1            ; Refill?
 367         bpl     2f
 368         lsrq    24, $r1     ; Get PGD index (bit 24-31)
 369         move.d  [current_pgd], $r0 ; PGD for the current process
 370         move.d  [$r0+$r1.d], $r0   ; Get PMD
 371         beq     2f
 372         nop
 373         and.w   PAGE_MASK, $r0     ; Remove PMD flags
 374         move.d  [R_MMU_CAUSE], $r1
 375         lsrq    PAGE_SHIFT, $r1
 376         and.d   0x7ff, $r1         ; Get PTE index into PGD (bit 13-23)
 377         move.d  [$r0+$r1.d], $r1   ; Get PTE
 378         beq     2f
 379         nop
 380         ;; Store in TLB
 381         move.d  $r1, [R_TLB_LO]
 382         ;; Return
 383         movem   [$sp+], $r1
 384         pop     $dccr
 385         rbf     [$sp+]          ; return by popping the CPU status
 386
 387 2:      ; PMD or PTE missing, let the mm subsystem fix it up.
 388         movem   [$sp+], $r1
 389         pop     $dccr
 390
 391         ; Ok, not that easy, pass it on to the mm subsystem
 392         ; The MMU status record is now on the stack
 393         push    $srp            ; make a stackframe similar to pt_regs
 394         push    $dccr
 395         push    $mof
 396         di
 397         subq    14*4, $sp
 398         movem   $r13, [$sp]
 399         push    $r10            ; dummy orig_r10
 400         moveq   1, $r10
 401         push    $r10            ; frametype == 1, BUSFAULT frame type
 402
 403         move.d  $sp, $r10       ; pt_regs argument to handle_mmu_bus_fault
 404
 405         jsr     handle_mmu_bus_fault  ; in arch/cris/arch-v10/mm/fault.c
 406
 407         ;; now we need to return through the normal path, we cannot just
 408         ;; do the RBFexit since we might have killed off the running
 409         ;; process due to a SEGV, scheduled due to a page blocking or
 410         ;; whatever.
 411
 412         moveq   0, $r9          ; busfault is equivalent to an irq
 413
 414         ba      ret_from_intr
 415         nop
 416
 417         ;; special handlers for breakpoint and NMI
 418 hwbreakpoint:
 419         push    $dccr
 420         di
 421         push    $r10
 422         push    $r11
 423         move.d  [hw_bp_trig_ptr],$r10
 424         move    $brp,$r11
 425         move.d  $r11,[$r10+]
 426         move.d  $r10,[hw_bp_trig_ptr]
 427 1:      pop     $r11
 428         pop     $r10
 429         pop     $dccr
 430         retb
 431         nop
 432
 433 IRQ1_interrupt:
 434         ;; this prologue MUST match the one in irq.h and the struct in ptregs.h!!!
 435         move    $brp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
 436         push    $srp
 437         push    $dccr
 438         push    $mof
 439         di
 440         subq    14*4, $sp
 441         movem   $r13, [$sp]
 442         push    $r10            ; push orig_r10
 443         clear.d [$sp=$sp-4]     ; frametype == 0, normal frame
 444
 445         ;; If there is a glitch on the NMI pin shorter than ~100ns
 446         ;; (i.e. non-active by the time we get here) then the nmi_pin bit
 447         ;; in R_IRQ_MASK0_RD will already be cleared.  The watchdog_nmi bit
 448         ;; is cleared by us however (when feeding the watchdog), which is why
 449         ;; we use that bit to determine what brought us here.
 450
 451         move.d  [R_IRQ_MASK0_RD], $r1 ; External NMI or watchdog?
 452         and.d   (1<<30), $r1
 453         bne     wdog
 454         move.d  $sp, $r10
 455         jsr     handle_nmi
 456         setf m                  ; Enable NMI again
 457         ba      _Rexit          ; Return the standard way
 458         nop
 459 wdog:
 460 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
 461 ;; Check if we're waiting for reset to happen, as signalled by
 462 ;; hard_reset_now setting cause_of_death to a magic value.  If so, just
 463 ;; get stuck until reset happens.
 464         .comm   cause_of_death, 4       ;; Don't declare this anywhere.
 465         move.d  [cause_of_death], $r10
 466         cmp.d   0xbedead, $r10
 467 _killed_by_death:
 468         beq     _killed_by_death
 469         nop
 470
 471 ;; We'll see this in ksymoops dumps.
 472 Watchdog_bite:
 473
 474 #ifdef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
 475        ;; We just restart the watchdog here to be sure we dont get
 476        ;; hit while printing the watchdogmsg below
 477        ;; This restart is compatible with the rest of the C-code, so
 478        ;; the C-code can keep restarting the watchdog after this point.
 479        ;; The non-NICE_DOGGY code below though, disables the possibility
 480        ;; to restart since it changes the watchdog key, to avoid any
 481        ;; buggy loops etc. keeping the watchdog alive after this.
 482        jsr     reset_watchdog
 483 #else
 484
 485 ;; We need to extend the 3.3ms after the NMI at watchdog bite, so we have
 486 ;; time for an oops-dump over a 115k2 serial wire.  Another 100ms should do.
 487
 488 ;; Change the watchdog key to an arbitrary 3-bit value and restart the
 489 ;; watchdog.
 490 #define WD_INIT 2
 491         moveq     IO_FIELD (R_WATCHDOG, key, WD_INIT), $r10
 492         move.d  R_WATCHDOG, $r11
 493
 494         move.d  $r10, [$r11]
 495         moveq     IO_FIELD (R_WATCHDOG, key,                            \
 496                             IO_EXTRACT (R_WATCHDOG, key,                \
 497                                         IO_MASK (R_WATCHDOG, key))      \
 498                             ^ WD_INIT)                                  \
 499                 | IO_STATE (R_WATCHDOG, enable, start), $r10
 500         move.d  $r10, [$r11]
 501
 502 #endif
 503
 504 ;; Note that we don't do "setf m" here (or after two necessary NOPs),
 505 ;; since *not* doing that saves us from re-entrancy checks.  We don't want
 506 ;; to get here again due to possible subsequent NMIs; we want the watchdog
 507 ;; to reset us.
 508
 509         move.d  _watchdogmsg,$r10
 510         jsr     printk
 511
 512         move.d  $sp, $r10
 513         jsr     watchdog_bite_hook
 514
 515 ;; This nop is here so we see the "Watchdog_bite" label in ksymoops dumps
 516 ;; rather than "spurious_interrupt".
 517         nop
 518 ;; At this point we drop down into spurious_interrupt, which will do a
 519 ;; hard reset.
 520
 521         .section .rodata,"a"
 522 _watchdogmsg:
 523         .ascii  "Oops: bitten by watchdog\n\0"
 524         .previous
 525
 526 #endif /* CONFIG_ETRAX_WATCHDOG and not CONFIG_SVINTO_SIM */
 527
 528 spurious_interrupt:
 529         di
 530         jump hard_reset_now
 531
 532         ;; this handles the case when multiple interrupts arrive at the same time
 533         ;; we jump to the first set interrupt bit in a priority fashion
 534         ;; the hardware will call the unserved interrupts after the handler finishes
 535
 536 multiple_interrupt:
 537         ;; this prologue MUST match the one in irq.h and the struct in ptregs.h!!!
 538         move    $irp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
 539         push    $srp
 540         push    $dccr
 541         push    $mof
 542         di
 543         subq    14*4, $sp
 544         movem   $r13, [$sp]
 545         push    $r10            ; push orig_r10
 546         clear.d [$sp=$sp-4]     ; frametype == 0, normal frame
 547
 548         move.d  $sp, $r10
 549         jsr     do_multiple_IRQ
 550
 551         jump    ret_from_intr
 552
 553 do_sigtrap:
 554         ;;
 555         ;; SIGTRAP the process that executed the break instruction.
 556         ;; Make a frame that Rexit in entry.S expects.
 557         ;;
 558         move    $brp, [$sp=$sp-16]      ; Push BRP while faking a cpu status record.
 559         push    $srp                    ; Push subroutine return pointer.
 560         push    $dccr                   ; Push condition codes.
 561         push    $mof                    ; Push multiply overflow reg.
 562         di                              ; Need to disable irq's at this point.
 563         subq    14*4, $sp               ; Make room for r0-r13.
 564         movem   $r13, [$sp]             ; Push the r0-r13 registers.
 565         push    $r10                    ; Push orig_r10.
 566         clear.d [$sp=$sp-4]             ; Frametype - this is a normal stackframe.
 567
 568         movs.w  -8192,$r9               ; THREAD_SIZE == 8192
 569         and.d   $sp, $r9
 570         move.d  [$r9+TI_task], $r10
 571         move.d  [$r10+TASK_pid], $r10   ; current->pid as arg1.
 572         moveq   5, $r11                 ; SIGTRAP as arg2.
 573         jsr     sys_kill
 574         jump    ret_from_intr           ; Use the return routine for interrupts.
 575
 576 gdb_handle_breakpoint:
 577         push    $dccr
 578         push    $r0
 579 #ifdef CONFIG_ETRAX_KGDB
 580         move    $dccr, $r0              ; U-flag not affected by previous insns.
 581         btstq   8, $r0                  ; Test the U-flag.
 582         bmi     _ugdb_handle_breakpoint ; Go to user mode debugging.
 583         nop                             ; Empty delay slot (cannot pop r0 here).
 584         pop     $r0                     ; Restore r0.
 585         ba      kgdb_handle_breakpoint  ; Go to kernel debugging.
 586         pop     $dccr                   ; Restore dccr in delay slot.
 587 #endif
 588
 589 _ugdb_handle_breakpoint:
 590         move    $brp, $r0               ; Use r0 temporarily for calculation.
 591         subq    2, $r0                  ; Set to address of previous instruction.
 592         move    $r0, $brp
 593         pop     $r0                     ; Restore r0.
 594         ba      do_sigtrap              ; SIGTRAP the offending process.
 595         pop     $dccr                   ; Restore dccr in delay slot.
 596
 597         .data
 598
 599 hw_bp_trigs:
 600         .space 64*4
 601 hw_bp_trig_ptr:
 602         .dword hw_bp_trigs
 603
 604         .section .rodata,"a"
 605 sys_call_table:
 606         .long sys_restart_syscall       /* 0 - old "setup()" system call, used for restarting */
 607         .long sys_exit
 608         .long sys_fork
 609         .long sys_read
 610         .long sys_write
 611         .long sys_open          /* 5 */
 612         .long sys_close
 613         .long sys_waitpid
 614         .long sys_creat
 615         .long sys_link
 616         .long sys_unlink        /* 10 */
 617         .long sys_execve
 618         .long sys_chdir
 619         .long sys_time
 620         .long sys_mknod
 621         .long sys_chmod         /* 15 */
 622         .long sys_lchown16
 623         .long sys_ni_syscall    /* old break syscall holder */
 624         .long sys_stat
 625         .long sys_lseek
 626         .long sys_getpid        /* 20 */
 627         .long sys_mount
 628         .long sys_oldumount
 629         .long sys_setuid16
 630         .long sys_getuid16
 631         .long sys_stime         /* 25 */
 632         .long sys_ptrace
 633         .long sys_alarm
 634         .long sys_fstat
 635         .long sys_pause
 636         .long sys_utime         /* 30 */
 637         .long sys_ni_syscall    /* old stty syscall holder */
 638         .long sys_ni_syscall    /* old gtty syscall holder */
 639         .long sys_access
 640         .long sys_nice
 641         .long sys_ni_syscall    /* 35  old ftime syscall holder */
 642         .long sys_sync
 643         .long sys_kill
 644         .long sys_rename
 645         .long sys_mkdir
 646         .long sys_rmdir         /* 40 */
 647         .long sys_dup
 648         .long sys_pipe
 649         .long sys_times
 650         .long sys_ni_syscall    /* old prof syscall holder */
 651         .long sys_brk           /* 45 */
 652         .long sys_setgid16
 653         .long sys_getgid16
 654         .long sys_signal
 655         .long sys_geteuid16
 656         .long sys_getegid16     /* 50 */
 657         .long sys_acct
 658         .long sys_umount        /* recycled never used phys( */
 659         .long sys_ni_syscall    /* old lock syscall holder */
 660         .long sys_ioctl
 661         .long sys_fcntl         /* 55 */
 662         .long sys_ni_syscall    /* old mpx syscall holder */
 663         .long sys_setpgid
 664         .long sys_ni_syscall    /* old ulimit syscall holder */
 665         .long sys_ni_syscall    /* old sys_olduname holder */
 666         .long sys_umask         /* 60 */
 667         .long sys_chroot
 668         .long sys_ustat
 669         .long sys_dup2
 670         .long sys_getppid
 671         .long sys_getpgrp       /* 65 */
 672         .long sys_setsid
 673         .long sys_sigaction
 674         .long sys_sgetmask
 675         .long sys_ssetmask
 676         .long sys_setreuid16    /* 70 */
 677         .long sys_setregid16
 678         .long sys_sigsuspend
 679         .long sys_sigpending
 680         .long sys_sethostname
 681         .long sys_setrlimit     /* 75 */
 682         .long sys_old_getrlimit
 683         .long sys_getrusage
 684         .long sys_gettimeofday
 685         .long sys_settimeofday
 686         .long sys_getgroups16   /* 80 */
 687         .long sys_setgroups16
 688         .long sys_select        /* was old_select in Linux/E100 */
 689         .long sys_symlink
 690         .long sys_lstat
 691         .long sys_readlink      /* 85 */
 692         .long sys_uselib
 693         .long sys_swapon
 694         .long sys_reboot
 695         .long sys_old_readdir
 696         .long sys_old_mmap      /* 90 */
 697         .long sys_munmap
 698         .long sys_truncate
 699         .long sys_ftruncate
 700         .long sys_fchmod
 701         .long sys_fchown16      /* 95 */
 702         .long sys_getpriority
 703         .long sys_setpriority
 704         .long sys_ni_syscall    /* old profil syscall holder */
 705         .long sys_statfs
 706         .long sys_fstatfs       /* 100 */
 707         .long sys_ni_syscall    /* sys_ioperm in i386 */
 708         .long sys_socketcall
 709         .long sys_syslog
 710         .long sys_setitimer
 711         .long sys_getitimer     /* 105 */
 712         .long sys_newstat
 713         .long sys_newlstat
 714         .long sys_newfstat
 715         .long sys_ni_syscall    /* old sys_uname holder */
 716         .long sys_ni_syscall    /* sys_iopl in i386 */
 717         .long sys_vhangup
 718         .long sys_ni_syscall    /* old "idle" system call */
 719         .long sys_ni_syscall    /* vm86old in i386 */
 720         .long sys_wait4
 721         .long sys_swapoff       /* 115 */
 722         .long sys_sysinfo
 723         .long sys_ipc
 724         .long sys_fsync
 725         .long sys_sigreturn
 726         .long sys_clone         /* 120 */
 727         .long sys_setdomainname
 728         .long sys_newuname
 729         .long sys_ni_syscall    /* sys_modify_ldt */
 730         .long sys_adjtimex
 731         .long sys_mprotect      /* 125 */
 732         .long sys_sigprocmask
 733         .long sys_ni_syscall    /* old "create_module" */
 734         .long sys_init_module
 735         .long sys_delete_module
 736         .long sys_ni_syscall    /* 130: old "get_kernel_syms" */
 737         .long sys_quotactl
 738         .long sys_getpgid
 739         .long sys_fchdir
 740         .long sys_bdflush
 741         .long sys_sysfs         /* 135 */
 742         .long sys_personality
 743         .long sys_ni_syscall    /* for afs_syscall */
 744         .long sys_setfsuid16
 745         .long sys_setfsgid16
 746         .long sys_llseek        /* 140 */
 747         .long sys_getdents
 748         .long sys_select
 749         .long sys_flock
 750         .long sys_msync
 751         .long sys_readv         /* 145 */
 752         .long sys_writev
 753         .long sys_getsid
 754         .long sys_fdatasync
 755         .long sys_sysctl
 756         .long sys_mlock         /* 150 */
 757         .long sys_munlock
 758         .long sys_mlockall
 759         .long sys_munlockall
 760         .long sys_sched_setparam
 761         .long sys_sched_getparam        /* 155 */
 762         .long sys_sched_setscheduler
 763         .long sys_sched_getscheduler
 764         .long sys_sched_yield
 765         .long sys_sched_get_priority_max
 766         .long sys_sched_get_priority_min        /* 160 */
 767         .long sys_sched_rr_get_interval
 768         .long sys_nanosleep
 769         .long sys_mremap
 770         .long sys_setresuid16
 771         .long sys_getresuid16   /* 165 */
 772         .long sys_ni_syscall    /* sys_vm86 */
 773         .long sys_ni_syscall    /* Old sys_query_module */
 774         .long sys_poll
 775         .long sys_ni_syscall    /* old nfsservctl */
 776         .long sys_setresgid16   /* 170 */
 777         .long sys_getresgid16
 778         .long sys_prctl
 779         .long sys_rt_sigreturn
 780         .long sys_rt_sigaction
 781         .long sys_rt_sigprocmask        /* 175 */
 782         .long sys_rt_sigpending
 783         .long sys_rt_sigtimedwait
 784         .long sys_rt_sigqueueinfo
 785         .long sys_rt_sigsuspend
 786         .long sys_pread64       /* 180 */
 787         .long sys_pwrite64
 788         .long sys_chown16
 789         .long sys_getcwd
 790         .long sys_capget
 791         .long sys_capset        /* 185 */
 792         .long sys_sigaltstack
 793         .long sys_sendfile
 794         .long sys_ni_syscall    /* streams1 */
 795         .long sys_ni_syscall    /* streams2 */
 796         .long sys_vfork         /* 190 */
 797         .long sys_getrlimit
 798         .long sys_mmap2
 799         .long sys_truncate64
 800         .long sys_ftruncate64
 801         .long sys_stat64        /* 195 */
 802         .long sys_lstat64
 803         .long sys_fstat64
 804         .long sys_lchown
 805         .long sys_getuid
 806         .long sys_getgid        /* 200 */
 807         .long sys_geteuid
 808         .long sys_getegid
 809         .long sys_setreuid
 810         .long sys_setregid
 811         .long sys_getgroups     /* 205 */
 812         .long sys_setgroups
 813         .long sys_fchown
 814         .long sys_setresuid
 815         .long sys_getresuid
 816         .long sys_setresgid     /* 210 */
 817         .long sys_getresgid
 818         .long sys_chown
 819         .long sys_setuid
 820         .long sys_setgid
 821         .long sys_setfsuid      /* 215 */
 822         .long sys_setfsgid
 823         .long sys_pivot_root
 824         .long sys_mincore
 825         .long sys_madvise
 826         .long sys_getdents64    /* 220 */
 827         .long sys_fcntl64
 828         .long sys_ni_syscall    /* reserved for TUX */
 829         .long sys_ni_syscall
 830         .long sys_gettid
 831         .long sys_readahead     /* 225 */
 832         .long sys_setxattr
 833         .long sys_lsetxattr
 834         .long sys_fsetxattr
 835         .long sys_getxattr
 836         .long sys_lgetxattr     /* 230 */
 837         .long sys_fgetxattr
 838         .long sys_listxattr
 839         .long sys_llistxattr
 840         .long sys_flistxattr
 841         .long sys_removexattr   /* 235 */
 842         .long sys_lremovexattr
 843         .long sys_fremovexattr
 844         .long sys_tkill
 845         .long sys_sendfile64
 846         .long sys_futex         /* 240 */
 847         .long sys_sched_setaffinity
 848         .long sys_sched_getaffinity
 849         .long sys_ni_syscall    /* sys_set_thread_area */
 850         .long sys_ni_syscall    /* sys_get_thread_area */
 851         .long sys_io_setup      /* 245 */
 852         .long sys_io_destroy
 853         .long sys_io_getevents
 854         .long sys_io_submit
 855         .long sys_io_cancel
 856         .long sys_fadvise64     /* 250 */
 857         .long sys_ni_syscall
 858         .long sys_exit_group
 859         .long sys_lookup_dcookie
 860         .long sys_epoll_create
 861         .long sys_epoll_ctl     /* 255 */
 862         .long sys_epoll_wait
 863         .long sys_remap_file_pages
 864         .long sys_set_tid_address
 865         .long sys_timer_create
 866         .long sys_timer_settime         /* 260 */
 867         .long sys_timer_gettime
 868         .long sys_timer_getoverrun
 869         .long sys_timer_delete
 870         .long sys_clock_settime
 871         .long sys_clock_gettime         /* 265 */
 872         .long sys_clock_getres
 873         .long sys_clock_nanosleep
 874         .long sys_statfs64
 875         .long sys_fstatfs64
 876         .long sys_tgkill        /* 270 */
 877         .long sys_utimes
 878         .long sys_fadvise64_64
 879         .long sys_ni_syscall    /* sys_vserver */
 880         .long sys_ni_syscall    /* sys_mbind */
 881         .long sys_ni_syscall    /* 275 sys_get_mempolicy */
 882         .long sys_ni_syscall    /* sys_set_mempolicy */
 883         .long sys_mq_open
 884         .long sys_mq_unlink
 885         .long sys_mq_timedsend
 886         .long sys_mq_timedreceive       /* 280 */
 887         .long sys_mq_notify
 888         .long sys_mq_getsetattr
 889         .long sys_ni_syscall            /* reserved for kexec */
 890         .long sys_waitid
 891         .long sys_ni_syscall            /* 285 */ /* available */
 892         .long sys_add_key
 893         .long sys_request_key
 894         .long sys_keyctl
 895         .long sys_ioprio_set
 896         .long sys_ioprio_get            /* 290 */
 897         .long sys_inotify_init
 898         .long sys_inotify_add_watch
 899         .long sys_inotify_rm_watch
 900         .long sys_migrate_pages
 901         .long sys_openat                /* 295 */
 902         .long sys_mkdirat
 903         .long sys_mknodat
 904         .long sys_fchownat
 905         .long sys_futimesat
 906         .long sys_fstatat64             /* 300 */
 907         .long sys_unlinkat
 908         .long sys_renameat
 909         .long sys_linkat
 910         .long sys_symlinkat
 911         .long sys_readlinkat            /* 305 */
 912         .long sys_fchmodat
 913         .long sys_faccessat
 914         .long sys_pselect6
 915         .long sys_ppoll
 916         .long sys_unshare               /* 310 */
 917         .long sys_set_robust_list
 918         .long sys_get_robust_list
 919         .long sys_splice
 920         .long sys_sync_file_range
 921         .long sys_tee                   /* 315 */
 922         .long sys_vmsplice
 923         .long sys_move_pages
 924         .long sys_getcpu
 925         .long sys_epoll_pwait
 926         .long sys_utimensat             /* 320 */
 927         .long sys_signalfd
 928         .long sys_timerfd_create
 929         .long sys_eventfd
 930         .long sys_fallocate
 931         .long sys_timerfd_settime       /* 325 */
 932         .long sys_timerfd_gettime
 933         .long sys_signalfd4
 934         .long sys_eventfd2
 935         .long sys_epoll_create1
 936         .long sys_dup3                  /* 330 */
 937         .long sys_pipe2
 938         .long sys_inotify_init1
 939         .long sys_preadv
 940         .long sys_pwritev
 941         .long sys_setns                 /* 335 */
 942
 943         /*
 944          * NOTE!! This doesn't have to be exact - we just have
 945          * to make sure we have _enough_ of the "sys_ni_syscall"
 946          * entries. Don't panic if you notice that this hasn't
 947          * been shrunk every time we add a new system call.
 948          */
 949
 950         .rept NR_syscalls-(.-sys_call_table)/4
 951                 .long sys_ni_syscall
 952         .endr
 953