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

   1 /* $Id: entry.S,v 1.23 2004/10/19 13:07:37 starvik Exp $
   2  *
   3  *  linux/arch/cris/entry.S
   4  *
   5  *  Copyright (C) 2000, 2001, 2002 Axis Communications AB
   6  *
   7  *  Authors:    Bjorn Wesen (bjornw@axis.com)
   8  *
   9  *  $Log: entry.S,v $
  10  *  Revision 1.23  2004/10/19 13:07:37  starvik
  11  *  Merge of Linux 2.6.9
  12  *
  13  *  Revision 1.22  2004/06/21 10:29:55  starvik
  14  *  Merge of Linux 2.6.7
  15  *
  16  *  Revision 1.21  2004/06/09 05:30:27  starvik
  17  *  Clean up multiple interrupt handling.
  18  *    Prevent interrupts from interrupting each other.
  19  *    Handle all active interrupts.
  20  *
  21  *  Revision 1.20  2004/06/08 08:55:32  starvik
  22  *  Removed unused code
  23  *
  24  *  Revision 1.19  2004/06/04 11:56:15  starvik
  25  *  Implemented page table lookup for refills in assembler for improved performance.
  26  *
  27  *  Revision 1.18  2004/05/11 12:28:25  starvik
  28  *  Merge of Linux 2.6.6
  29  *
  30  *  Revision 1.17  2003/09/11 07:29:49  starvik
  31  *  Merge of Linux 2.6.0-test5
  32  *
  33  *  Revision 1.16  2003/07/04 08:27:41  starvik
  34  *  Merge of Linux 2.5.74
  35  *
  36  *  Revision 1.15  2003/04/09 07:32:55  starvik
  37  *  resume should return task_struct, not thread_info
  38  *
  39  *  Revision 1.14  2003/04/09 05:20:44  starvik
  40  *  Merge of Linux 2.5.67
  41  *
  42  *  Revision 1.13  2002/12/11 15:42:02  starvik
  43  *  Extracted v10 (ETRAX 100LX) specific stuff from arch/cris/kernel/*.c
  44  *
  45  *  Revision 1.12  2002/12/10 09:00:10  starvik
  46  *  Merge of Linux 2.5.51
  47  *
  48  *  Revision 1.11  2002/12/05 07:53:10  starvik
  49  *  Corrected constants used with btstq
  50  *
  51  *  Revision 1.10  2002/11/27 08:45:10  starvik
  52  *  pid is in task_struct, not thread_info
  53  *
  54  *  Revision 1.9  2002/11/26 09:52:05  starvik
  55  *  Added preemptive kernel scheduling (if CONFIG_PREEMPT)
  56  *
  57  *  Revision 1.8  2002/11/20 11:56:11  starvik
  58  *  Merge of Linux 2.5.48
  59  *
  60  *  Revision 1.7  2002/11/18 13:02:42  starvik
  61  *  Added fourth parameter to do_notify_resume
  62  *  Minor cleanup
  63  *
  64  *  Revision 1.6  2002/11/11 10:37:50  starvik
  65  *  Use new asm-offset defines
  66  *  Modified for new location of current->work etc
  67  *  Removed SYMBOL_NAME from syscalls
  68  *  Added some new syscalls
  69  *
  70  *  Revision 1.5  2002/11/05 06:45:11  starvik
  71  *  Merge of Linux 2.5.45
  72  *
  73  *  Revision 1.4  2002/02/05 15:41:31  bjornw
  74  *  Rewritten to conform better to current 2.5 code (similar to arch/i386)
  75  *
  76  *  Revision 1.3  2002/01/21 15:22:20  bjornw
  77  *  NICE_DOGGY fix from 2.4 arch/cris
  78  *
  79  *  Revision 1.37  2001/12/07 17:03:55  bjornw
  80  *  Call a c-hook called watchdog_bite_hook instead of show_registers directly
  81  *
  82  *  Revision 1.36  2001/11/22 13:36:36  bjornw
  83  *  * In ret_from_intr, check regs->dccr for usermode reentrance instead of
  84  *    DCCR explicitely (because the latter might not reflect current reality)
  85  *  * In mmu_bus_fault, set $r9 _after_ calling the C-code instead of before
  86  *    since $r9 is call-clobbered and is potentially needed afterwards
  87  *
  88  *  Revision 1.35  2001/10/30 17:10:15  bjornw
  89  *  Add some syscalls
  90  *
  91  *  Revision 1.34  2001/10/01 14:45:03  bjornw
  92  *  Removed underscores and added register prefixes
  93  *
  94  *  Revision 1.33  2001/08/21 13:48:01  jonashg
  95  *  Added fix by HP to avoid oops when doing a hard_reset_now.
  96  *
  97  *  Revision 1.32  2001/08/14 04:32:02  hp
  98  *  In _resume, add comment why R9 is saved; don't sound like it's call-saved.
  99  *
 100  *  Revision 1.31  2001/07/25 16:07:42  bjornw
 101  *  softirq_active/mask -> softirq_pending only
 102  *
 103  *  Revision 1.30  2001/07/05 01:03:32  hp
 104  *  - include asm/errno.h to get ENOSYS.
 105  *  - Use ENOSYS, not local constant LENOSYS; tweak comments.
 106  *  - Explain why .include, not #include is used.
 107  *  - Make oops-register-dump if watchdog bits and it's not expected.
 108  *  - Don't jsr, use jump _hard_reset_now, and skip spurious nop.
 109  *  - Use correct section attribute for section .rodata.
 110  *  - Adjust sys_ni_syscall fill number.
 111  *
 112  *  Revision 1.29  2001/06/25 14:07:00  hp
 113  *      Fix review comment.
 114  *      * head.S: Use IO_STATE, IO_FIELD and IO_MASK constructs instead of
 115  *      magic numbers.  Add comment that -traditional must not be used.
 116  *      * entry.S (SYMBOL_NAME): Change redefinition to use ## concatenation.
 117  *      Correct and update comment.
 118  *      * Makefile (.S.o): Don't use -traditional.  Add comment why the
 119  *      toplevel rule can't be used (now that there's a reason).
 120  *
 121  *  Revision 1.28  2001/06/21 02:00:40  hp
 122  *      * entry.S: Include asm/unistd.h.
 123  *      (_sys_call_table): Use section .rodata, not .data.
 124  *      (_kernel_thread): Move from...
 125  *      * process.c: ... here.
 126  *      * entryoffsets.c (VAL): Break out from...
 127  *      (OF): Use VAL.
 128  *      (LCLONE_VM): New asmified value from CLONE_VM.
 129  *
 130  *  Revision 1.27  2001/05/29 11:25:27  markusl
 131  *  In case of "spurious_interrupt", do hard_reset instead of hanging system in a loop...
 132  *
 133  *  Revision 1.26  2001/05/15 15:46:03  bjornw
 134  *  Include config.h now that we use some CONFIG_ options
 135  *
 136  *  Revision 1.25  2001/05/15 05:38:47  hp
 137  *  Tweaked code in _ret_from_sys_call
 138  *
 139  *  Revision 1.24  2001/05/15 05:27:49  hp
 140  *  Save r9 in r1 over function call rather than on stack.
 141  *
 142  *  Revision 1.23  2001/05/15 05:10:00  hp
 143  *  Generate entry.S structure offsets from C
 144  *
 145  *  Revision 1.22  2001/04/17 13:58:39  orjanf
 146  *  * Renamed CONFIG_KGDB to CONFIG_ETRAX_KGDB.
 147  *
 148  *  Revision 1.21  2001/04/17 11:33:29  orjanf
 149  *  Updated according to review:
 150  *  * Included asm/sv_addr_ag.h to get macro for internal register.
 151  *  * Corrected comment regarding system call argument passing.
 152  *  * Removed comment about instruction being in a delay slot.
 153  *  * Added comment about SYMBOL_NAME macro.
 154  *
 155  *  Revision 1.20  2001/04/12 08:51:07  hp
 156  *  - Add entry for sys_fcntl64.  In fact copy last piece from i386 including ...
 157  *  - .rept to fill table to safe state with sys_ni_syscall.
 158  *
 159  *  Revision 1.19  2001/04/04 09:43:32  orjanf
 160  *  * Moved do_sigtrap from traps.c to entry.S.
 161  *  * LTASK_PID need not be global anymore.
 162  *
 163  *  Revision 1.18  2001/03/26 09:25:02  markusl
 164  *  Updated after review, should now handle USB interrupts correctly.
 165  *
 166  *  Revision 1.17  2001/03/21 16:12:55  bjornw
 167  *  * Always make room for the cpu status record in the frame, in order to
 168  *    use the same framelength and layout for both mmu busfaults and normal
 169  *    irqs. No need to check for the explicit CRIS_FRAME_FIXUP type anymore.
 170  *  * Fixed bug with using addq for popping the stack in the epilogue - it
 171  *    destroyed the flag register. Use instructions that don't affect the
 172  *    flag register instead.
 173  *  * Removed write to R_PORT_PA_DATA during spurious_interrupt
 174  *
 175  *  Revision 1.16  2001/03/20 19:43:02  bjornw
 176  *  * Get rid of esp0 setting
 177  *  * Give a 7th argument to a systemcall - the stackframe
 178  *
 179  *  Revision 1.15  2001/03/05 13:14:30  bjornw
 180  *  Spelling fix
 181  *
 182  *  Revision 1.14  2001/02/23 08:36:36  perf
 183  *  New ABI; syscallnr=r9, arg5=mof, arg6=srp.
 184  *  Corrected tracesys call check.
 185  *
 186  *  Revision 1.13  2001/02/15 08:40:55  perf
 187  *  H-P by way of perf;
 188  *  - (_system_call): Don't read system call function address into r1.
 189  *  - (RBFExit): There is no such thing as a null pop.  Adjust sp by addq.
 190  *  - (_system_call): Don't use r10 and don't save and restore it.
 191  *  - (THREAD_ESP0): New constant.
 192  *  - (_system_call): Inline set_esp0.
 193  *
 194  *  Revision 1.12  2001/01/31 17:56:25  orjanf
 195  *  Added definition of LTASK_PID and made it global.
 196  *
 197  *  Revision 1.11  2001/01/10 21:13:29  bjornw
 198  *  SYMBOL_NAME is defined incorrectly for the compiler options we currently use
 199  *
 200  *  Revision 1.10  2000/12/18 23:47:56  bjornw
 201  *  * Added syscall trace support (ptrace), completely untested of course
 202  *  * Removed redundant check for NULL entries in syscall_table
 203  *
 204  *  Revision 1.9  2000/11/21 16:40:51  bjornw
 205  *  * New frame type used when an SBFS frame needs to be popped without
 206  *    actually restarting the instruction
 207  *  * Enable interrupts in signal_return (they did so in x86, I hope it's a good
 208  *    idea)
 209  *
 210  *  Revision 1.8  2000/11/17 16:53:35  bjornw
 211  *  Added detection of frame-type in Rexit, so that mmu_bus_fault can
 212  *  use ret_from_intr in the return-path to check for signals (like SEGV)
 213  *  and other foul things that might have occurred during the fault.
 214  *
 215  *  Revision 1.7  2000/10/06 15:04:28  bjornw
 216  *  Include mof in register savings
 217  *
 218  *  Revision 1.6  2000/09/12 16:02:44  bjornw
 219  *  Linux-2.4.0-test7 derived updates
 220  *
 221  *  Revision 1.5  2000/08/17 15:35:15  bjornw
 222  *  2.4.0-test6 changed local_irq_count and friends API
 223  *
 224  *  Revision 1.4  2000/08/02 13:59:30  bjornw
 225  *  Removed olduname and uname from the syscall list
 226  *
 227  *  Revision 1.3  2000/07/31 13:32:58  bjornw
 228  *  * Export ret_from_intr
 229  *  * _resume updated (prev/last tjohejsan)
 230  *  * timer_interrupt obsolete
 231  *  * SIGSEGV detection in mmu_bus_fault temporarily disabled
 232  *
 233  *
 234  */
 235
 236 /*
 237  * entry.S contains the system-call and fault low-level handling routines.
 238  *
 239  * NOTE: This code handles signal-recognition, which happens every time
 240  * after a timer-interrupt and after each system call.
 241  *
 242  * Stack layout in 'ret_from_system_call':
 243  *      ptrace needs to have all regs on the stack.
 244  *      if the order here is changed, it needs to be
 245  *      updated in fork.c:copy_process, signal.c:do_signal,
 246  *      ptrace.c and ptrace.h
 247  *
 248  */
 249
 250 #include <linux/config.h>
 251 #include <linux/linkage.h>
 252 #include <linux/sys.h>
 253 #include <asm/unistd.h>
 254 #include <asm/arch/sv_addr_ag.h>
 255 #include <asm/errno.h>
 256 #include <asm/thread_info.h>
 257 #include <asm/arch/offset.h>
 258 #include <asm/page.h>
 259 #include <asm/pgtable.h>
 260
 261         ;; functions exported from this file
 262
 263         .globl system_call
 264         .globl ret_from_intr
 265         .globl ret_from_fork
 266         .globl resume
 267         .globl multiple_interrupt
 268         .globl hwbreakpoint
 269         .globl IRQ1_interrupt
 270         .globl spurious_interrupt
 271         .globl hw_bp_trigs
 272         .globl mmu_bus_fault
 273         .globl do_sigtrap
 274         .globl gdb_handle_breakpoint
 275         .globl sys_call_table
 276
 277         ;; below are various parts of system_call which are not in the fast-path
 278
 279 #ifdef CONFIG_PREEMPT
 280         ; Check if preemptive kernel scheduling should be done
 281 _resume_kernel:
 282         ; Load current task struct
 283         movs.w  -8192, $r0      ;  THREAD_SIZE = 8192
 284         and.d   $sp, $r0
 285         move.d  [$r0+TI_preempt_count], $r10    ;  Preemption disabled?
 286         bne     _Rexit
 287         nop
 288 _need_resched:
 289         move.d  [$r0+TI_flags], $r10
 290         btstq   TIF_NEED_RESCHED, $r10  ; Check if need_resched is set
 291         bpl     _Rexit
 292         nop
 293         ; Ok, lets's do some preemptive kernel scheduling
 294         move.d  PREEMPT_ACTIVE, $r10
 295         move.d  $r10, [$r0+TI_preempt_count] ; Mark as active
 296         ei
 297         jsr     schedule
 298         clear.d [$r0+TI_preempt_count] ;  Mark as inactive
 299         di
 300         ; Load new task struct
 301         movs.w  -8192, $r0      ;  THREAD_SIZE = 8192
 302         and.d   $sp, $r0
 303         ; One more time (with new task)
 304         ba      _need_resched
 305         nop
 306 #else
 307 #define _resume_kernel _Rexit
 308 #endif
 309
 310         ; Called at exit from fork. schedule_tail must be called to drop
 311         ; spinlock if CONFIG_PREEMPT
 312 ret_from_fork:
 313         jsr schedule_tail
 314         ba  ret_from_sys_call
 315         nop
 316
 317 ret_from_intr:
 318         ;; check for resched if preemptive kernel or if we're going back to user-mode
 319         ;; this test matches the user_regs(regs) macro
 320         ;; we cannot simply test $dccr, because that does not necessarily
 321         ;; reflect what mode we'll return into.
 322
 323         move.d  [$sp + PT_dccr], $r0; regs->dccr
 324         btstq   8, $r0          ; U-flag
 325         bpl     _resume_kernel
 326         ; Note that di below is in delay slot
 327
 328 _resume_userspace:
 329         di                      ; so need_resched and sigpending don't change
 330
 331         movs.w  -8192, $r0      ; THREAD_SIZE == 8192
 332         and.d   $sp, $r0
 333
 334         move.d  [$r0+TI_flags], $r10    ; current->work
 335         and.d   _TIF_WORK_MASK, $r10    ; is there any work to be done on return
 336         bne     _work_pending
 337         nop
 338         ba      _Rexit
 339         nop
 340
 341         ;; The system_call is called by a BREAK instruction, which works like
 342         ;; an interrupt call but it stores the return PC in BRP instead of IRP.
 343         ;; Since we dont really want to have two epilogues (one for system calls
 344         ;; and one for interrupts) we push the contents of BRP instead of IRP in the
 345         ;; system call prologue, to make it look like an ordinary interrupt on the
 346         ;; stackframe.
 347         ;;
 348         ;; Since we can't have system calls inside interrupts, it should not matter
 349         ;; that we don't stack IRP.
 350         ;;
 351         ;; In r9 we have the wanted syscall number. Arguments come in r10,r11,r12,r13,mof,srp
 352         ;;
 353         ;; This function looks on the _surface_ like spaghetti programming, but it's
 354         ;; really designed so that the fast-path does not force cache-loading of non-used
 355         ;; instructions. Only the non-common cases cause the outlined code to run..
 356
 357 system_call:
 358         ;; stack-frame similar to the irq heads, which is reversed in ret_from_sys_call
 359         move    $brp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
 360         push    $srp
 361         push    $dccr
 362         push    $mof
 363         subq    14*4, $sp               ; make room for r0-r13
 364         movem   $r13, [$sp]     ; push r0-r13
 365         push    $r10            ; push orig_r10
 366         clear.d [$sp=$sp-4]     ; frametype == 0, normal stackframe
 367
 368         movs.w  -ENOSYS, $r0
 369         move.d  $r0, [$sp+PT_r10]       ; put the default return value in r10 in the frame
 370
 371         ;; check if this process is syscall-traced
 372
 373         movs.w  -8192, $r0      ; THREAD_SIZE == 8192
 374         and.d   $sp, $r0
 375
 376         move.d  [$r0+TI_flags], $r0
 377         btstq   TIF_SYSCALL_TRACE, $r0
 378         bmi     _syscall_trace_entry
 379         nop
 380
 381 _syscall_traced:
 382
 383         ;; check for sanity in the requested syscall number
 384
 385         cmpu.w  NR_syscalls, $r9
 386         bcc     ret_from_sys_call
 387         lslq    2, $r9          ;  multiply by 4, in the delay slot
 388
 389         ;; as a bonus 7th parameter, we give the location on the stack
 390         ;; of the register structure itself. some syscalls need this.
 391
 392         push    $sp
 393
 394         ;; the parameter carrying registers r10, r11, r12 and 13 are intact.
 395         ;; the fifth and sixth parameters (if any) was in mof and srp
 396         ;; respectively, and we need to put them on the stack.
 397
 398         push    $srp
 399         push    $mof
 400
 401         jsr     [$r9+sys_call_table]    ; actually do the system call
 402         addq    3*4, $sp                ; pop the mof, srp and regs parameters
 403         move.d  $r10, [$sp+PT_r10]      ; save the return value
 404
 405         moveq   1, $r9          ; "parameter" to ret_from_sys_call to show it was a sys call
 406
 407         ;; fall through into ret_from_sys_call to return
 408
 409 ret_from_sys_call:
 410         ;; r9 is a parameter - if >=1 we came from a syscall, if 0, from an irq
 411
 412         ;; get the current task-struct pointer (see top for defs)
 413
 414         movs.w  -8192, $r0      ; THREAD_SIZE == 8192
 415         and.d   $sp, $r0
 416
 417         di                      ; make sure need_resched and sigpending don't change
 418         move.d  [$r0+TI_flags],$r1
 419         and.d   _TIF_ALLWORK_MASK, $r1
 420         bne     _syscall_exit_work
 421         nop
 422
 423 _Rexit:
 424         ;; this epilogue MUST match the prologues in multiple_interrupt, irq.h and ptregs.h
 425         pop     $r10            ; frametype
 426         bne     _RBFexit        ; was not CRIS_FRAME_NORMAL, handle otherwise
 427         addq    4, $sp          ; skip orig_r10, in delayslot
 428         movem   [$sp+], $r13    ; registers r0-r13
 429         pop     $mof            ; multiply overflow register
 430         pop     $dccr           ; condition codes
 431         pop     $srp            ; subroutine return pointer
 432         ;; now we have a 4-word SBFS frame which we do not want to restore
 433         ;; using RBF since it was not stacked with SBFS. instead we would like to
 434         ;; just get the PC value to restart it with, and skip the rest of
 435         ;; the frame.
 436         ;; Also notice that it's important to use instructions here that
 437         ;; keep the interrupts disabled (since we've already popped DCCR)
 438         move    [$sp=$sp+16], $p8; pop the SBFS frame from the sp
 439         jmpu    [$sp-16]        ; return through the irp field in the sbfs frame
 440
 441 _RBFexit:
 442         movem   [$sp+], $r13    ; registers r0-r13, in delay slot
 443         pop     $mof            ; multiply overflow register
 444         pop     $dccr           ; condition codes
 445         pop     $srp            ; subroutine return pointer
 446         rbf     [$sp+]          ; return by popping the CPU status
 447
 448         ;; We get here after doing a syscall if extra work might need to be done
 449         ;; perform syscall exit tracing if needed
 450
 451 _syscall_exit_work:
 452         ;; $r0 contains current at this point and irq's are disabled
 453
 454         move.d  [$r0+TI_flags], $r1
 455         btstq   TIF_SYSCALL_TRACE, $r1
 456         bpl     _work_pending
 457         nop
 458
 459         ei
 460
 461         move.d  $r9, $r1        ; preserve r9
 462         jsr     do_syscall_trace
 463         move.d  $r1, $r9
 464
 465         ba      _resume_userspace
 466         nop
 467
 468 _work_pending:
 469         move.d  [$r0+TI_flags], $r1
 470         btstq   TIF_NEED_RESCHED, $r1
 471         bpl     _work_notifysig ; was neither trace nor sched, must be signal/notify
 472         nop
 473
 474 _work_resched:
 475         move.d  $r9, $r1        ; preserve r9
 476         jsr     schedule
 477         move.d  $r1, $r9
 478         di
 479
 480         move.d  [$r0+TI_flags], $r1
 481         and.d   _TIF_WORK_MASK, $r1; ignore the syscall trace counter
 482         beq     _Rexit
 483         nop
 484         btstq   TIF_NEED_RESCHED, $r1
 485         bmi     _work_resched   ; current->work.need_resched
 486         nop
 487
 488 _work_notifysig:
 489         ;; deal with pending signals and notify-resume requests
 490
 491         move.d  $r9, $r10       ; do_notify_resume syscall/irq param
 492         moveq   0, $r11         ; oldset param - 0 in this case
 493         move.d  $sp, $r12       ; the regs param
 494         move.d  $r1, $r13       ; the thread_info_flags parameter
 495         jsr     do_notify_resume
 496
 497         ba _Rexit
 498         nop
 499
 500         ;; We get here as a sidetrack when we've entered a syscall with the
 501         ;; trace-bit set. We need to call do_syscall_trace and then continue
 502         ;; with the call.
 503
 504 _syscall_trace_entry:
 505         ;; PT_r10 in the frame contains -ENOSYS as required, at this point
 506
 507         jsr     do_syscall_trace
 508
 509         ;; now re-enter the syscall code to do the syscall itself
 510         ;; we need to restore $r9 here to contain the wanted syscall, and
 511         ;; the other parameter-bearing registers
 512
 513         move.d  [$sp+PT_r9], $r9
 514         move.d  [$sp+PT_orig_r10], $r10  ; PT_r10 is already filled with -ENOSYS.
 515         move.d  [$sp+PT_r11],      $r11
 516         move.d  [$sp+PT_r12],      $r12
 517         move.d  [$sp+PT_r13],      $r13
 518         move    [$sp+PT_mof],      $mof
 519         move    [$sp+PT_srp],      $srp
 520
 521         ba      _syscall_traced
 522         nop
 523
 524         ;; resume performs the actual task-switching, by switching stack pointers
 525         ;; input arguments: r10 = prev, r11 = next, r12 = thread offset in task struct
 526         ;; returns old current in r10
 527         ;;
 528         ;; TODO:  see the i386 version. The switch_to which calls resume in our version
 529         ;;        could really be an inline asm of this.
 530
 531 resume:
 532         push    $srp                     ; we keep the old/new PC on the stack
 533         add.d   $r12, $r10               ; r10 = current tasks tss
 534         move    $dccr, [$r10+THREAD_dccr]; save irq enable state
 535         di
 536
 537         move    $usp, [$r10+ THREAD_usp] ; save user-mode stackpointer
 538
 539         ;; See copy_thread for the reason why register R9 is saved.
 540         subq    10*4, $sp
 541         movem   $r9, [$sp]               ; save non-scratch registers and R9.
 542
 543         move.d  $sp, [$r10+THREAD_ksp]   ; save the kernel stack pointer for the old task
 544         move.d  $sp, $r10                ; return last running task in r10
 545         and.d   -8192, $r10              ; get thread_info from stackpointer
 546         move.d  [$r10+TI_task], $r10     ; get task
 547         add.d   $r12, $r11               ; find the new tasks tss
 548         move.d  [$r11+THREAD_ksp], $sp   ; switch into the new stackframe by restoring kernel sp
 549
 550         movem   [$sp+], $r9              ; restore non-scratch registers and R9.
 551
 552         move    [$r11+THREAD_usp], $usp ; restore user-mode stackpointer
 553
 554         move    [$r11+THREAD_dccr], $dccr ; restore irq enable status
 555         jump    [$sp+]                   ; restore PC
 556
 557         ;; This is the MMU bus fault handler.
 558         ;; It needs to stack the CPU status and overall is different
 559         ;; from the other interrupt handlers.
 560
 561 mmu_bus_fault:
 562         ;; For refills we try to do a quick page table lookup. If it is
 563         ;; a real fault we let the mm subsystem handle it.
 564
 565         ;; the first longword in the sbfs frame was the interrupted PC
 566         ;; which fits nicely with the "IRP" slot in pt_regs normally used to
 567         ;; contain the return address. used by Oops to print kernel errors.
 568         sbfs    [$sp=$sp-16]    ; push the internal CPU status
 569         push    $dccr
 570         di
 571         subq    2*4, $sp
 572         movem   $r1, [$sp]
 573         move.d  [R_MMU_CAUSE], $r1
 574         ;; ETRAX 100LX TR89 bugfix: if the second half of an unaligned
 575         ;; write causes a MMU-fault, it will not be restarted correctly.
 576         ;; This could happen if a write crosses a page-boundary and the
 577         ;; second page is not yet COW'ed or even loaded. The workaround
 578         ;; is to clear the unaligned bit in the CPU status record, so
 579         ;; that the CPU will rerun both the first and second halves of
 580         ;; the instruction. This will not have any sideeffects unless
 581         ;; the first half goes to any device or memory that can't be
 582         ;; written twice, and which is mapped through the MMU.
 583         ;;
 584         ;; We only need to do this for writes.
 585         btstq   8, $r1             ; Write access?
 586         bpl     1f
 587         nop
 588         move.d  [$sp+16], $r0      ; Clear unaligned bit in csrinstr
 589         and.d   ~(1<<5), $r0
 590         move.d  $r0, [$sp+16]
 591 1:      btstq   12, $r1            ; Refill?
 592         bpl     2f
 593         lsrq    PMD_SHIFT, $r1     ; Get PMD index into PGD (bit 24-31)
 594         move.d  [current_pgd], $r0 ; PGD for the current process
 595         move.d  [$r0+$r1.d], $r0   ; Get PMD
 596         beq     2f
 597         nop
 598         and.w   PAGE_MASK, $r0     ; Remove PMD flags
 599         move.d  [R_MMU_CAUSE], $r1
 600         lsrq    PAGE_SHIFT, $r1
 601         and.d   0x7ff, $r1         ; Get PTE index into PMD (bit 13-24)
 602         move.d  [$r0+$r1.d], $r1   ; Get PTE
 603         beq     2f
 604         nop
 605         ;; Store in TLB
 606         move.d  $r1, [R_TLB_LO]
 607         ;; Return
 608         movem   [$sp+], $r1
 609         pop     $dccr
 610         rbf     [$sp+]          ; return by popping the CPU status
 611
 612 2:      ; PMD or PTE missing, let the mm subsystem fix it up.
 613         movem   [$sp+], $r1
 614         pop     $dccr
 615
 616         ; Ok, not that easy, pass it on to the mm subsystem
 617         ; The MMU status record is now on the stack
 618         push    $srp            ; make a stackframe similar to pt_regs
 619         push    $dccr
 620         push    $mof
 621         di
 622         subq    14*4, $sp
 623         movem   $r13, [$sp]
 624         push    $r10            ; dummy orig_r10
 625         moveq   1, $r10
 626         push    $r10            ; frametype == 1, BUSFAULT frame type
 627
 628         move.d  $sp, $r10       ; pt_regs argument to handle_mmu_bus_fault
 629
 630         jsr     handle_mmu_bus_fault  ; in arch/cris/arch-v10/mm/fault.c
 631
 632         ;; now we need to return through the normal path, we cannot just
 633         ;; do the RBFexit since we might have killed off the running
 634         ;; process due to a SEGV, scheduled due to a page blocking or
 635         ;; whatever.
 636
 637         moveq   0, $r9          ; busfault is equivalent to an irq
 638
 639         ba      ret_from_intr
 640         nop
 641
 642         ;; special handlers for breakpoint and NMI
 643 hwbreakpoint:
 644         push    $dccr
 645         di
 646         push    $r10
 647         push    $r11
 648         move.d  [hw_bp_trig_ptr],$r10
 649         move    $brp,$r11
 650         move.d  $r11,[$r10+]
 651         move.d  $r10,[hw_bp_trig_ptr]
 652 1:      pop     $r11
 653         pop     $r10
 654         pop     $dccr
 655         retb
 656         nop
 657
 658 IRQ1_interrupt:
 659
 660 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
 661 ;; If we receive a watchdog interrupt while it is not expected, then set
 662 ;; up a canonical frame and dump register contents before dying.
 663
 664         ;; this prologue MUST match the one in irq.h and the struct in ptregs.h!!!
 665         move    $brp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
 666         push    $srp
 667         push    $dccr
 668         push    $mof
 669         di
 670         subq    14*4, $sp
 671         movem   $r13, [$sp]
 672         push    $r10            ; push orig_r10
 673         clear.d [$sp=$sp-4]     ; frametype == 0, normal frame
 674
 675 ;; We don't check that we actually were bit by the watchdog as opposed to
 676 ;; an external NMI, since there is currently no handler for external NMI.
 677
 678 ;; Check if we're waiting for reset to happen, as signalled by
 679 ;; hard_reset_now setting cause_of_death to a magic value.  If so, just
 680 ;; get stuck until reset happens.
 681         .comm   cause_of_death, 4       ;; Don't declare this anywhere.
 682         move.d  [cause_of_death], $r10
 683         cmp.d   0xbedead, $r10
 684 _killed_by_death:
 685         beq     _killed_by_death
 686         nop
 687
 688 ;; We'll see this in ksymoops dumps.
 689 Watchdog_bite:
 690
 691 #ifdef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
 692        ;; We just restart the watchdog here to be sure we dont get
 693        ;; hit while printing the watchdogmsg below
 694        ;; This restart is compatible with the rest of the C-code, so
 695        ;; the C-code can keep restarting the watchdog after this point.
 696        ;; The non-NICE_DOGGY code below though, disables the possibility
 697        ;; to restart since it changes the watchdog key, to avoid any
 698        ;; buggy loops etc. keeping the watchdog alive after this.
 699        jsr     reset_watchdog
 700 #else
 701
 702 ;; We need to extend the 3.3ms after the NMI at watchdog bite, so we have
 703 ;; time for an oops-dump over a 115k2 serial wire.  Another 100ms should do.
 704
 705 ;; Change the watchdog key to an arbitrary 3-bit value and restart the
 706 ;; watchdog.
 707 #define WD_INIT 2
 708         moveq     IO_FIELD (R_WATCHDOG, key, WD_INIT), $r10
 709         move.d  R_WATCHDOG, $r11
 710
 711         move.d  $r10, [$r11]
 712         moveq     IO_FIELD (R_WATCHDOG, key,                            \
 713                             IO_EXTRACT (R_WATCHDOG, key,                \
 714                                         IO_MASK (R_WATCHDOG, key))      \
 715                             ^ WD_INIT)                                  \
 716                 | IO_STATE (R_WATCHDOG, enable, start), $r10
 717         move.d  $r10, [$r11]
 718
 719 #endif
 720
 721 ;; Note that we don't do "setf m" here (or after two necessary NOPs),
 722 ;; since *not* doing that saves us from re-entrancy checks.  We don't want
 723 ;; to get here again due to possible subsequent NMIs; we want the watchdog
 724 ;; to reset us.
 725
 726         move.d  _watchdogmsg,$r10
 727         jsr     printk
 728
 729         move.d  $sp, $r10
 730         jsr     watchdog_bite_hook
 731
 732 ;; This nop is here so we see the "Watchdog_bite" label in ksymoops dumps
 733 ;; rather than "spurious_interrupt".
 734         nop
 735 ;; At this point we drop down into spurious_interrupt, which will do a
 736 ;; hard reset.
 737
 738         .section .rodata,"a"
 739 _watchdogmsg:
 740         .ascii  "Oops: bitten by watchdog\n\0"
 741         .previous
 742
 743 #endif /* CONFIG_ETRAX_WATCHDOG and not CONFIG_SVINTO_SIM */
 744
 745 spurious_interrupt:
 746         di
 747         jump hard_reset_now
 748
 749         ;; this handles the case when multiple interrupts arrive at the same time
 750         ;; we jump to the first set interrupt bit in a priority fashion
 751         ;; the hardware will call the unserved interrupts after the handler finishes
 752
 753 multiple_interrupt:
 754         ;; this prologue MUST match the one in irq.h and the struct in ptregs.h!!!
 755         move    $irp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
 756         push    $srp
 757         push    $dccr
 758         push    $mof
 759         di
 760         subq    14*4, $sp
 761         movem   $r13, [$sp]
 762         push    $r10            ; push orig_r10
 763         clear.d [$sp=$sp-4]     ; frametype == 0, normal frame
 764
 765         moveq   2, $r2          ; first bit we care about is the timer0 irq
 766         move.d  [R_VECT_MASK_RD], $r0; read the irq bits that triggered the multiple irq
 767         move.d  $r0, [R_VECT_MASK_CLR] ; Block all active IRQs
 768 1:
 769         btst    $r2, $r0        ; check for the irq given by bit r2
 770         bpl     2f
 771         move.d  $r2, $r10       ; First argument to do_IRQ
 772         move.d  $sp, $r11       ; second argument to do_IRQ
 773         jsr     do_IRQ
 774 2:
 775         addq    1, $r2          ; next vector bit
 776         cmp.b   32, $r2
 777         bne     1b      ; process all irq's up to and including number 31
 778         moveq   0, $r9  ; make ret_from_intr realise we came from an ir
 779
 780         move.d  $r0, [R_VECT_MASK_SET] ;  Unblock all the IRQs
 781         jump    ret_from_intr
 782
 783 do_sigtrap:
 784         ;;
 785         ;; SIGTRAP the process that executed the break instruction.
 786         ;; Make a frame that Rexit in entry.S expects.
 787         ;;
 788         move    $brp, [$sp=$sp-16]      ; Push BRP while faking a cpu status record.
 789         push    $srp                    ; Push subroutine return pointer.
 790         push    $dccr                   ; Push condition codes.
 791         push    $mof                    ; Push multiply overflow reg.
 792         di                              ; Need to disable irq's at this point.
 793         subq    14*4, $sp               ; Make room for r0-r13.
 794         movem   $r13, [$sp]             ; Push the r0-r13 registers.
 795         push    $r10                    ; Push orig_r10.
 796         clear.d [$sp=$sp-4]             ; Frametype - this is a normal stackframe.
 797
 798         movs.w  -8192,$r9               ; THREAD_SIZE == 8192
 799         and.d   $sp, $r9
 800         move.d  [$r9+TI_task], $r10
 801         move.d  [$r10+TASK_pid], $r10   ; current->pid as arg1.
 802         moveq   5, $r11                 ; SIGTRAP as arg2.
 803         jsr     sys_kill
 804         jump    ret_from_intr           ; Use the return routine for interrupts.
 805
 806 gdb_handle_breakpoint:
 807         push    $dccr
 808         push    $r0
 809 #ifdef CONFIG_ETRAX_KGDB
 810         move    $dccr, $r0              ; U-flag not affected by previous insns.
 811         btstq   8, $r0                  ; Test the U-flag.
 812         bmi     _ugdb_handle_breakpoint ; Go to user mode debugging.
 813         nop                             ; Empty delay slot (cannot pop r0 here).
 814         pop     $r0                     ; Restore r0.
 815         ba      kgdb_handle_breakpoint  ; Go to kernel debugging.
 816         pop     $dccr                   ; Restore dccr in delay slot.
 817 #endif
 818
 819 _ugdb_handle_breakpoint:
 820         move    $brp, $r0               ; Use r0 temporarily for calculation.
 821         subq    2, $r0                  ; Set to address of previous instruction.
 822         move    $r0, $brp
 823         pop     $r0                     ; Restore r0.
 824         ba      do_sigtrap              ; SIGTRAP the offending process.
 825         pop     $dccr                   ; Restore dccr in delay slot.
 826
 827         .data
 828
 829 hw_bp_trigs:
 830         .space 64*4
 831 hw_bp_trig_ptr:
 832         .dword hw_bp_trigs
 833
 834         .section .rodata,"a"
 835 sys_call_table:
 836         .long sys_restart_syscall       /* 0 - old "setup()" system call, used for restarting */
 837         .long sys_exit
 838         .long sys_fork
 839         .long sys_read
 840         .long sys_write
 841         .long sys_open          /* 5 */
 842         .long sys_close
 843         .long sys_waitpid
 844         .long sys_creat
 845         .long sys_link
 846         .long sys_unlink        /* 10 */
 847         .long sys_execve
 848         .long sys_chdir
 849         .long sys_time
 850         .long sys_mknod
 851         .long sys_chmod         /* 15 */
 852         .long sys_lchown16
 853         .long sys_ni_syscall    /* old break syscall holder */
 854         .long sys_stat
 855         .long sys_lseek
 856         .long sys_getpid        /* 20 */
 857         .long sys_mount
 858         .long sys_oldumount
 859         .long sys_setuid16
 860         .long sys_getuid16
 861         .long sys_stime         /* 25 */
 862         .long sys_ptrace
 863         .long sys_alarm
 864         .long sys_fstat
 865         .long sys_pause
 866         .long sys_utime         /* 30 */
 867         .long sys_ni_syscall    /* old stty syscall holder */
 868         .long sys_ni_syscall    /* old gtty syscall holder */
 869         .long sys_access
 870         .long sys_nice
 871         .long sys_ni_syscall    /* 35  old ftime syscall holder */
 872         .long sys_sync
 873         .long sys_kill
 874         .long sys_rename
 875         .long sys_mkdir
 876         .long sys_rmdir         /* 40 */
 877         .long sys_dup
 878         .long sys_pipe
 879         .long sys_times
 880         .long sys_ni_syscall    /* old prof syscall holder */
 881         .long sys_brk           /* 45 */
 882         .long sys_setgid16
 883         .long sys_getgid16
 884         .long sys_signal
 885         .long sys_geteuid16
 886         .long sys_getegid16     /* 50 */
 887         .long sys_acct
 888         .long sys_umount        /* recycled never used phys( */
 889         .long sys_ni_syscall    /* old lock syscall holder */
 890         .long sys_ioctl
 891         .long sys_fcntl         /* 55 */
 892         .long sys_ni_syscall    /* old mpx syscall holder */
 893         .long sys_setpgid
 894         .long sys_ni_syscall    /* old ulimit syscall holder */
 895         .long sys_ni_syscall    /* old sys_olduname holder */
 896         .long sys_umask         /* 60 */
 897         .long sys_chroot
 898         .long sys_ustat
 899         .long sys_dup2
 900         .long sys_getppid
 901         .long sys_getpgrp       /* 65 */
 902         .long sys_setsid
 903         .long sys_sigaction
 904         .long sys_sgetmask
 905         .long sys_ssetmask
 906         .long sys_setreuid16    /* 70 */
 907         .long sys_setregid16
 908         .long sys_sigsuspend
 909         .long sys_sigpending
 910         .long sys_sethostname
 911         .long sys_setrlimit     /* 75 */
 912         .long sys_old_getrlimit
 913         .long sys_getrusage
 914         .long sys_gettimeofday
 915         .long sys_settimeofday
 916         .long sys_getgroups16   /* 80 */
 917         .long sys_setgroups16
 918         .long sys_select        /* was old_select in Linux/E100 */
 919         .long sys_symlink
 920         .long sys_lstat
 921         .long sys_readlink      /* 85 */
 922         .long sys_uselib
 923         .long sys_swapon
 924         .long sys_reboot
 925         .long old_readdir
 926         .long old_mmap          /* 90 */
 927         .long sys_munmap
 928         .long sys_truncate
 929         .long sys_ftruncate
 930         .long sys_fchmod
 931         .long sys_fchown16      /* 95 */
 932         .long sys_getpriority
 933         .long sys_setpriority
 934         .long sys_ni_syscall    /* old profil syscall holder */
 935         .long sys_statfs
 936         .long sys_fstatfs       /* 100 */
 937         .long sys_ni_syscall    /* sys_ioperm in i386 */
 938         .long sys_socketcall
 939         .long sys_syslog
 940         .long sys_setitimer
 941         .long sys_getitimer     /* 105 */
 942         .long sys_newstat
 943         .long sys_newlstat
 944         .long sys_newfstat
 945         .long sys_ni_syscall    /* old sys_uname holder */
 946         .long sys_ni_syscall    /* sys_iopl in i386 */
 947         .long sys_vhangup
 948         .long sys_ni_syscall    /* old "idle" system call */
 949         .long sys_ni_syscall    /* vm86old in i386 */
 950         .long sys_wait4
 951         .long sys_swapoff       /* 115 */
 952         .long sys_sysinfo
 953         .long sys_ipc
 954         .long sys_fsync
 955         .long sys_sigreturn
 956         .long sys_clone         /* 120 */
 957         .long sys_setdomainname
 958         .long sys_newuname
 959         .long sys_ni_syscall    /* sys_modify_ldt */
 960         .long sys_adjtimex
 961         .long sys_mprotect      /* 125 */
 962         .long sys_sigprocmask
 963         .long sys_ni_syscall    /* old "create_module" */
 964         .long sys_init_module
 965         .long sys_delete_module
 966         .long sys_ni_syscall    /* 130: old "get_kernel_syms" */
 967         .long sys_quotactl
 968         .long sys_getpgid
 969         .long sys_fchdir
 970         .long sys_bdflush
 971         .long sys_sysfs         /* 135 */
 972         .long sys_personality
 973         .long sys_ni_syscall    /* for afs_syscall */
 974         .long sys_setfsuid16
 975         .long sys_setfsgid16
 976         .long sys_llseek        /* 140 */
 977         .long sys_getdents
 978         .long sys_select
 979         .long sys_flock
 980         .long sys_msync
 981         .long sys_readv         /* 145 */
 982         .long sys_writev
 983         .long sys_getsid
 984         .long sys_fdatasync
 985         .long sys_sysctl
 986         .long sys_mlock         /* 150 */
 987         .long sys_munlock
 988         .long sys_mlockall
 989         .long sys_munlockall
 990         .long sys_sched_setparam
 991         .long sys_sched_getparam        /* 155 */
 992         .long sys_sched_setscheduler
 993         .long sys_sched_getscheduler
 994         .long sys_sched_yield
 995         .long sys_sched_get_priority_max
 996         .long sys_sched_get_priority_min        /* 160 */
 997         .long sys_sched_rr_get_interval
 998         .long sys_nanosleep
 999         .long sys_mremap
1000         .long sys_setresuid16
1001         .long sys_getresuid16   /* 165 */
1002         .long sys_ni_syscall    /* sys_vm86 */
1003         .long sys_ni_syscall    /* Old sys_query_module */
1004         .long sys_poll
1005         .long sys_nfsservctl
1006         .long sys_setresgid16   /* 170 */
1007         .long sys_getresgid16
1008         .long sys_prctl
1009         .long sys_rt_sigreturn
1010         .long sys_rt_sigaction
1011         .long sys_rt_sigprocmask        /* 175 */
1012         .long sys_rt_sigpending
1013         .long sys_rt_sigtimedwait
1014         .long sys_rt_sigqueueinfo
1015         .long sys_rt_sigsuspend
1016         .long sys_pread64       /* 180 */
1017         .long sys_pwrite64
1018         .long sys_chown16
1019         .long sys_getcwd
1020         .long sys_capget
1021         .long sys_capset        /* 185 */
1022         .long sys_sigaltstack
1023         .long sys_sendfile
1024         .long sys_ni_syscall    /* streams1 */
1025         .long sys_ni_syscall    /* streams2 */
1026         .long sys_vfork         /* 190 */
1027         .long sys_getrlimit
1028         .long sys_mmap2
1029         .long sys_truncate64
1030         .long sys_ftruncate64
1031         .long sys_stat64        /* 195 */
1032         .long sys_lstat64
1033         .long sys_fstat64
1034         .long sys_lchown
1035         .long sys_getuid
1036         .long sys_getgid        /* 200 */
1037         .long sys_geteuid
1038         .long sys_getegid
1039         .long sys_setreuid
1040         .long sys_setregid
1041         .long sys_getgroups     /* 205 */
1042         .long sys_setgroups
1043         .long sys_fchown
1044         .long sys_setresuid
1045         .long sys_getresuid
1046         .long sys_setresgid     /* 210 */
1047         .long sys_getresgid
1048         .long sys_chown
1049         .long sys_setuid
1050         .long sys_setgid
1051         .long sys_setfsuid      /* 215 */
1052         .long sys_setfsgid
1053         .long sys_pivot_root
1054         .long sys_mincore
1055         .long sys_madvise
1056         .long sys_getdents64    /* 220 */
1057         .long sys_fcntl64
1058         .long sys_ni_syscall    /* reserved for TUX */
1059         .long sys_ni_syscall
1060         .long sys_gettid
1061         .long sys_readahead     /* 225 */
1062         .long sys_setxattr
1063         .long sys_lsetxattr
1064         .long sys_fsetxattr
1065         .long sys_getxattr
1066         .long sys_lgetxattr     /* 230 */
1067         .long sys_fgetxattr
1068         .long sys_listxattr
1069         .long sys_llistxattr
1070         .long sys_flistxattr
1071         .long sys_removexattr   /* 235 */
1072         .long sys_lremovexattr
1073         .long sys_fremovexattr
1074         .long sys_tkill
1075         .long sys_sendfile64
1076         .long sys_futex         /* 240 */
1077         .long sys_sched_setaffinity
1078         .long sys_sched_getaffinity
1079         .long sys_ni_syscall    /* sys_set_thread_area */
1080         .long sys_ni_syscall    /* sys_get_thread_area */
1081         .long sys_io_setup      /* 245 */
1082         .long sys_io_destroy
1083         .long sys_io_getevents
1084         .long sys_io_submit
1085         .long sys_io_cancel
1086         .long sys_fadvise64     /* 250 */
1087         .long sys_ni_syscall
1088         .long sys_exit_group
1089         .long sys_lookup_dcookie
1090         .long sys_epoll_create
1091         .long sys_epoll_ctl     /* 255 */
1092         .long sys_epoll_wait
1093         .long sys_remap_file_pages
1094         .long sys_set_tid_address
1095         .long sys_timer_create
1096         .long sys_timer_settime         /* 260 */
1097         .long sys_timer_gettime
1098         .long sys_timer_getoverrun
1099         .long sys_timer_delete
1100         .long sys_clock_settime
1101         .long sys_clock_gettime         /* 265 */
1102         .long sys_clock_getres
1103         .long sys_clock_nanosleep
1104         .long sys_statfs64
1105         .long sys_fstatfs64
1106         .long sys_tgkill        /* 270 */
1107         .long sys_utimes
1108         .long sys_fadvise64_64
1109         .long sys_ni_syscall    /* sys_vserver */
1110         .long sys_ni_syscall    /* sys_mbind */
1111         .long sys_ni_syscall    /* 275 sys_get_mempolicy */
1112         .long sys_ni_syscall    /* sys_set_mempolicy */
1113         .long sys_mq_open
1114         .long sys_mq_unlink
1115         .long sys_mq_timedsend
1116         .long sys_mq_timedreceive       /* 280 */
1117         .long sys_mq_notify
1118         .long sys_mq_getsetattr
1119         .long sys_ni_syscall            /* reserved for kexec */
1120         .long sys_waitid
1121
1122         /*
1123          * NOTE!! This doesn't have to be exact - we just have
1124          * to make sure we have _enough_ of the "sys_ni_syscall"
1125          * entries. Don't panic if you notice that this hasn't
1126          * been shrunk every time we add a new system call.
1127          */
1128
1129         .rept NR_syscalls-(.-sys_call_table)/4
1130                 .long sys_ni_syscall
1131         .endr
1132