path: root/arch/cris/arch-v10/kernel/entry.S

/* $Id: entry.S,v 1.28 2005/06/20 05:06:30 starvik Exp $
 *
 *  linux/arch/cris/entry.S
 *
 *  Copyright (C) 2000, 2001, 2002 Axis Communications AB
 *
 *  Authors:	Bjorn Wesen (bjornw@axis.com)
 *
 *  $Log: entry.S,v $
 *  Revision 1.28  2005/06/20 05:06:30  starvik
 *  Remove unnecessary diff to kernel.org tree
 *
 *  Revision 1.27  2005/03/04 08:16:16  starvik
 *  Merge of Linux 2.6.11.
 *
 *  Revision 1.26  2005/01/11 13:49:47  starvik
 *  Added NMI handler.
 *
 *  Revision 1.25  2004/12/27 11:18:32  starvik
 *  Merge of Linux 2.6.10 (not functional yet).
 *
 *  Revision 1.24  2004/12/22 10:41:23  starvik
 *  Updates to make v10 compile with the latest SMP aware generic code (even
 *  though v10 will never have SMP).
 *
 *  Revision 1.23  2004/10/19 13:07:37  starvik
 *  Merge of Linux 2.6.9
 *
 *  Revision 1.22  2004/06/21 10:29:55  starvik
 *  Merge of Linux 2.6.7
 *
 *  Revision 1.21  2004/06/09 05:30:27  starvik
 *  Clean up multiple interrupt handling.
 *    Prevent interrupts from interrupting each other.
 *    Handle all active interrupts.
 *
 *  Revision 1.20  2004/06/08 08:55:32  starvik
 *  Removed unused code
 *
 *  Revision 1.19  2004/06/04 11:56:15  starvik
 *  Implemented page table lookup for refills in assembler for improved performance.
 *
 *  Revision 1.18  2004/05/11 12:28:25  starvik
 *  Merge of Linux 2.6.6
 *
 *  Revision 1.17  2003/09/11 07:29:49  starvik
 *  Merge of Linux 2.6.0-test5
 *
 *  Revision 1.16  2003/07/04 08:27:41  starvik
 *  Merge of Linux 2.5.74
 *
 *  Revision 1.15  2003/04/09 07:32:55  starvik
 *  resume should return task_struct, not thread_info
 *
 *  Revision 1.14  2003/04/09 05:20:44  starvik
 *  Merge of Linux 2.5.67
 *
 *  Revision 1.13  2002/12/11 15:42:02  starvik
 *  Extracted v10 (ETRAX 100LX) specific stuff from arch/cris/kernel/*.c
 *
 *  Revision 1.12  2002/12/10 09:00:10  starvik
 *  Merge of Linux 2.5.51
 *
 *  Revision 1.11  2002/12/05 07:53:10  starvik
 *  Corrected constants used with btstq
 *
 *  Revision 1.10  2002/11/27 08:45:10  starvik
 *  pid is in task_struct, not thread_info
 *
 *  Revision 1.9  2002/11/26 09:52:05  starvik
 *  Added preemptive kernel scheduling (if CONFIG_PREEMPT)
 *
 *  Revision 1.8  2002/11/20 11:56:11  starvik
 *  Merge of Linux 2.5.48
 *
 *  Revision 1.7  2002/11/18 13:02:42  starvik
 *  Added fourth parameter to do_notify_resume
 *  Minor cleanup
 *
 *  Revision 1.6  2002/11/11 10:37:50  starvik
 *  Use new asm-offset defines
 *  Modified for new location of current->work etc
 *  Removed SYMBOL_NAME from syscalls
 *  Added some new syscalls
 *
 *  Revision 1.5  2002/11/05 06:45:11  starvik
 *  Merge of Linux 2.5.45
 *
 *  Revision 1.4  2002/02/05 15:41:31  bjornw
 *  Rewritten to conform better to current 2.5 code (similar to arch/i386)
 *
 *  Revision 1.3  2002/01/21 15:22:20  bjornw
 *  NICE_DOGGY fix from 2.4 arch/cris
 *
 *  Revision 1.37  2001/12/07 17:03:55  bjornw
 *  Call a c-hook called watchdog_bite_hook instead of show_registers directly
 *
 *  Revision 1.36  2001/11/22 13:36:36  bjornw
 *  * In ret_from_intr, check regs->dccr for usermode reentrance instead of
 *    DCCR explicitly (because the latter might not reflect current reality)
 *  * In mmu_bus_fault, set $r9 _after_ calling the C-code instead of before
 *    since $r9 is call-clobbered and is potentially needed afterwards
 *
 *  Revision 1.35  2001/10/30 17:10:15  bjornw
 *  Add some syscalls
 *
 *  Revision 1.34  2001/10/01 14:45:03  bjornw
 *  Removed underscores and added register prefixes
 *
 *  Revision 1.33  2001/08/21 13:48:01  jonashg
 *  Added fix by HP to avoid oops when doing a hard_reset_now.
 *
 *  Revision 1.32  2001/08/14 04:32:02  hp
 *  In _resume, add comment why R9 is saved; don't sound like it's call-saved.
 *
 *  Revision 1.31  2001/07/25 16:07:42  bjornw
 *  softirq_active/mask -> softirq_pending only
 *
 *  Revision 1.30  2001/07/05 01:03:32  hp
 *  - include asm/errno.h to get ENOSYS.
 *  - Use ENOSYS, not local constant LENOSYS; tweak comments.
 *  - Explain why .include, not #include is used.
 *  - Make oops-register-dump if watchdog bits and it's not expected.
 *  - Don't jsr, use jump _hard_reset_now, and skip spurious nop.
 *  - Use correct section attribute for section .rodata.
 *  - Adjust sys_ni_syscall fill number.
 *
 *  Revision 1.29  2001/06/25 14:07:00  hp
 *  	Fix review comment.
 *  	* head.S: Use IO_STATE, IO_FIELD and IO_MASK constructs instead of
 *  	magic numbers.  Add comment that -traditional must not be used.
 *  	* entry.S (SYMBOL_NAME): Change redefinition to use ## concatenation.
 *  	Correct and update comment.
 *  	* Makefile (.S.o): Don't use -traditional.  Add comment why the
 *  	toplevel rule can't be used (now that there's a reason).
 *
 *  Revision 1.28  2001/06/21 02:00:40  hp
 *  	* entry.S: Include asm/unistd.h.
 *  	(_sys_call_table): Use section .rodata, not .data.
 *  	(_kernel_thread): Move from...
 *  	* process.c: ... here.
 *  	* entryoffsets.c (VAL): Break out from...
 *  	(OF): Use VAL.
 *  	(LCLONE_VM): New asmified value from CLONE_VM.
 *
 *  Revision 1.27  2001/05/29 11:25:27  markusl
 *  In case of "spurious_interrupt", do hard_reset instead of hanging system in a loop...
 *
 *  Revision 1.26  2001/05/15 15:46:03  bjornw
 *  Include config.h now that we use some CONFIG_ options
 *
 *  Revision 1.25  2001/05/15 05:38:47  hp
 *  Tweaked code in _ret_from_sys_call
 *
 *  Revision 1.24  2001/05/15 05:27:49  hp
 *  Save r9 in r1 over function call rather than on stack.
 *
 *  Revision 1.23  2001/05/15 05:10:00  hp
 *  Generate entry.S structure offsets from C
 *
 *  Revision 1.22  2001/04/17 13:58:39  orjanf
 *  * Renamed CONFIG_KGDB to CONFIG_ETRAX_KGDB.
 *
 *  Revision 1.21  2001/04/17 11:33:29  orjanf
 *  Updated according to review:
 *  * Included asm/sv_addr_ag.h to get macro for internal register.
 *  * Corrected comment regarding system call argument passing.
 *  * Removed comment about instruction being in a delay slot.
 *  * Added comment about SYMBOL_NAME macro.
 *
 *  Revision 1.20  2001/04/12 08:51:07  hp
 *  - Add entry for sys_fcntl64.  In fact copy last piece from i386 including ...
 *  - .rept to fill table to safe state with sys_ni_syscall.
 *
 *  Revision 1.19  2001/04/04 09:43:32  orjanf
 *  * Moved do_sigtrap from traps.c to entry.S.
 *  * LTASK_PID need not be global anymore.
 *
 *  Revision 1.18  2001/03/26 09:25:02  markusl
 *  Updated after review, should now handle USB interrupts correctly.
 *
 *  Revision 1.17  2001/03/21 16:12:55  bjornw
 *  * Always make room for the cpu status record in the frame, in order to
 *    use the same framelength and layout for both mmu busfaults and normal
 *    irqs. No need to check for the explicit CRIS_FRAME_FIXUP type anymore.
 *  * Fixed bug with using addq for popping the stack in the epilogue - it
 *    destroyed the flag register. Use instructions that don't affect the
 *    flag register instead.
 *  * Removed write to R_PORT_PA_DATA during spurious_interrupt
 *
 *  Revision 1.16  2001/03/20 19:43:02  bjornw
 *  * Get rid of esp0 setting
 *  * Give a 7th argument to a systemcall - the stackframe
 *
 *  Revision 1.15  2001/03/05 13:14:30  bjornw
 *  Spelling fix
 *
 *  Revision 1.14  2001/02/23 08:36:36  perf
 *  New ABI; syscallnr=r9, arg5=mof, arg6=srp.
 *  Corrected tracesys call check.
 *
 *  Revision 1.13  2001/02/15 08:40:55  perf
 *  H-P by way of perf;
 *  - (_system_call): Don't read system call function address into r1.
 *  - (RBFExit): There is no such thing as a null pop.  Adjust sp by addq.
 *  - (_system_call): Don't use r10 and don't save and restore it.
 *  - (THREAD_ESP0): New constant.
 *  - (_system_call): Inline set_esp0.
 *
 *  Revision 1.12  2001/01/31 17:56:25  orjanf
 *  Added definition of LTASK_PID and made it global.
 *
 *  Revision 1.11  2001/01/10 21:13:29  bjornw
 *  SYMBOL_NAME is defined incorrectly for the compiler options we currently use
 *
 *  Revision 1.10  2000/12/18 23:47:56  bjornw
 *  * Added syscall trace support (ptrace), completely untested of course
 *  * Removed redundant check for NULL entries in syscall_table
 *
 *  Revision 1.9  2000/11/21 16:40:51  bjornw
 *  * New frame type used when an SBFS frame needs to be popped without
 *    actually restarting the instruction
 *  * Enable interrupts in signal_return (they did so in x86, I hope it's a good
 *    idea)
 *
 *  Revision 1.8  2000/11/17 16:53:35  bjornw
 *  Added detection of frame-type in Rexit, so that mmu_bus_fault can
 *  use ret_from_intr in the return-path to check for signals (like SEGV)
 *  and other foul things that might have occurred during the fault.
 *
 *  Revision 1.7  2000/10/06 15:04:28  bjornw
 *  Include mof in register savings
 *
 *  Revision 1.6  2000/09/12 16:02:44  bjornw
 *  Linux-2.4.0-test7 derived updates
 *
 *  Revision 1.5  2000/08/17 15:35:15  bjornw
 *  2.4.0-test6 changed local_irq_count and friends API
 *
 *  Revision 1.4  2000/08/02 13:59:30  bjornw
 *  Removed olduname and uname from the syscall list
 *
 *  Revision 1.3  2000/07/31 13:32:58  bjornw
 *  * Export ret_from_intr
 *  * _resume updated (prev/last tjohejsan)
 *  * timer_interrupt obsolete
 *  * SIGSEGV detection in mmu_bus_fault temporarily disabled
 *
 *
 */

/*
 * entry.S contains the system-call and fault low-level handling routines.
 *
 * NOTE: This code handles signal-recognition, which happens every time
 * after a timer-interrupt and after each system call.
 *
 * Stack layout in 'ret_from_system_call':
 * 	ptrace needs to have all regs on the stack.
 *	if the order here is changed, it needs to be 
 *	updated in fork.c:copy_process, signal.c:do_signal,
 *	ptrace.c and ptrace.h
 *
 */

#include <linux/linkage.h>
#include <linux/sys.h>
#include <asm/unistd.h>
#include <asm/arch/sv_addr_ag.h>
#include <asm/errno.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/page.h>
#include <asm/pgtable.h>

	;; functions exported from this file
	
	.globl system_call
	.globl ret_from_intr
	.globl ret_from_fork
	.globl resume
	.globl multiple_interrupt
	.globl hwbreakpoint
	.globl IRQ1_interrupt
	.globl spurious_interrupt
	.globl hw_bp_trigs
	.globl mmu_bus_fault
	.globl do_sigtrap
	.globl gdb_handle_breakpoint
	.globl sys_call_table
	
	;; below are various parts of system_call which are not in the fast-path
	
#ifdef CONFIG_PREEMPT	
	; Check if preemptive kernel scheduling should be done
_resume_kernel:
	di
	; Load current task struct
	movs.w	-8192, $r0	;  THREAD_SIZE = 8192
	and.d	$sp, $r0
	move.d	[$r0+TI_preempt_count], $r10	;  Preemption disabled?
	bne	_Rexit
	nop
_need_resched:
	move.d	[$r0+TI_flags], $r10
	btstq	TIF_NEED_RESCHED, $r10	; Check if need_resched is set
	bpl	_Rexit
	nop
	; Ok, lets's do some preemptive kernel scheduling
	jsr	preempt_schedule_irq
	; Load new task struct
	movs.w	-8192, $r0	;  THREAD_SIZE = 8192
	and.d	$sp, $r0
	; One more time (with new task)
	ba	_need_resched
	nop
#else
#define _resume_kernel _Rexit
#endif	

	; Called at exit from fork. schedule_tail must be called to drop
	; spinlock if CONFIG_PREEMPT
ret_from_fork:
	jsr schedule_tail
	ba  ret_from_sys_call
	nop
		
ret_from_intr:
	;; check for resched if preemptive kernel or if we're going back to user-mode 
	;; this test matches the user_regs(regs) macro
	;; we cannot simply test $dccr, because that does not necessarily
	;; reflect what mode we'll return into.
	
	move.d	[$sp + PT_dccr], $r0; regs->dccr
	btstq	8, $r0		; U-flag
	bpl     _resume_kernel
	; Note that di below is in delay slot 
	
_resume_userspace:
	di			; so need_resched and sigpending don't change

	movs.w	-8192, $r0	; THREAD_SIZE == 8192
	and.d	$sp, $r0

	move.d	[$r0+TI_flags], $r10	; current->work
	and.d	_TIF_WORK_MASK, $r10	; is there any work to be done on return
	bne	_work_pending
	nop
	ba	_Rexit
	nop
	
	;; The system_call is called by a BREAK instruction, which works like
	;; an interrupt call but it stores the return PC in BRP instead of IRP.
	;; Since we dont really want to have two epilogues (one for system calls
	;; and one for interrupts) we push the contents of BRP instead of IRP in the
	;; system call prologue, to make it look like an ordinary interrupt on the
	;; stackframe.
	;;
	;; Since we can't have system calls inside interrupts, it should not matter
	;; that we don't stack IRP.
	;; 
	;; In r9 we have the wanted syscall number. Arguments come in r10,r11,r12,r13,mof,srp
	;;
	;; This function looks on the _surface_ like spaghetti programming, but it's
	;; really designed so that the fast-path does not force cache-loading of non-used
	;; instructions. Only the non-common cases cause the outlined code to run..

system_call:
	;; stack-frame similar to the irq heads, which is reversed in ret_from_sys_call
	move	$brp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
	push	$srp
	push	$dccr
	push	$mof
	subq	14*4, $sp		; make room for r0-r13
	movem	$r13, [$sp]	; push r0-r13
	push	$r10		; push orig_r10
	clear.d [$sp=$sp-4]	; frametype == 0, normal stackframe
	
	movs.w	-ENOSYS, $r0
	move.d	$r0, [$sp+PT_r10]	; put the default return value in r10 in the frame

	;; check if this process is syscall-traced

	movs.w	-8192, $r0	; THREAD_SIZE == 8192
	and.d	$sp, $r0
	
	move.d	[$r0+TI_flags], $r0
	btstq   TIF_SYSCALL_TRACE, $r0
	bmi	_syscall_trace_entry
	nop	

_syscall_traced:	

	;; check for sanity in the requested syscall number
	
	cmpu.w	NR_syscalls, $r9	
	bcc	ret_from_sys_call
	lslq	2, $r9		;  multiply by 4, in the delay slot

	;; as a bonus 7th parameter, we give the location on the stack
	;; of the register structure itself. some syscalls need this.

	push	$sp
	
	;; the parameter carrying registers r10, r11, r12 and 13 are intact.
	;; the fifth and sixth parameters (if any) was in mof and srp 
	;; respectively, and we need to put them on the stack.

	push	$srp
	push	$mof
	
	jsr	[$r9+sys_call_table]	; actually do the system call
	addq	3*4, $sp		; pop the mof, srp and regs parameters
	move.d	$r10, [$sp+PT_r10]	; save the return value

	moveq	1, $r9		; "parameter" to ret_from_sys_call to show it was a sys call
	
	;; fall through into ret_from_sys_call to return
	
ret_from_sys_call:
	;; r9 is a parameter - if >=1 we came from a syscall, if 0, from an irq
		
	;; get the current task-struct pointer (see top for defs)

	movs.w	-8192, $r0	; THREAD_SIZE == 8192 
	and.d	$sp, $r0

	di			; make sure need_resched and sigpending don't change
	move.d	[$r0+TI_flags],$r1
	and.d	_TIF_ALLWORK_MASK, $r1
	bne	_syscall_exit_work
	nop

_Rexit:
	;; this epilogue MUST match the prologues in multiple_interrupt, irq.h and ptregs.h
	pop	$r10		; frametype
	bne	_RBFexit	; was not CRIS_FRAME_NORMAL, handle otherwise
	addq	4, $sp		; skip orig_r10, in delayslot
	movem	[$sp+], $r13	; registers r0-r13
	pop	$mof		; multiply overflow register 
	pop	$dccr		; condition codes
	pop	$srp		; subroutine return pointer
	;; now we have a 4-word SBFS frame which we do not want to restore
	;; using RBF since it was not stacked with SBFS. instead we would like to
	;; just get the PC value to restart it with, and skip the rest of
	;; the frame.
	;; Also notice that it's important to use instructions here that
	;; keep the interrupts disabled (since we've already popped DCCR)
	move	[$sp=$sp+16], $p8; pop the SBFS frame from the sp
	jmpu	[$sp-16]	; return through the irp field in the sbfs frame

_RBFexit:
	movem	[$sp+], $r13	; registers r0-r13, in delay slot
	pop	$mof		; multiply overflow register 
	pop	$dccr		; condition codes
	pop	$srp		; subroutine return pointer
	rbf	[$sp+]		; return by popping the CPU status

	;; We get here after doing a syscall if extra work might need to be done
	;; perform syscall exit tracing if needed
	
_syscall_exit_work:
	;; $r0 contains current at this point and irq's are disabled

	move.d  [$r0+TI_flags], $r1
	btstq	TIF_SYSCALL_TRACE, $r1
	bpl	_work_pending
	nop
	
	ei

	move.d	$r9, $r1	; preserve r9
	jsr	do_syscall_trace
	move.d	$r1, $r9
	
	ba	_resume_userspace
	nop
	
_work_pending:
	move.d  [$r0+TI_flags], $r1
	btstq   TIF_NEED_RESCHED, $r1
	bpl	_work_notifysig	; was neither trace nor sched, must be signal/notify
	nop
	
_work_resched:
	move.d	$r9, $r1	; preserve r9
	jsr	schedule
	move.d	$r1, $r9
	di

	move.d	[$r0+TI_flags], $r1
	and.d	_TIF_WORK_MASK, $r1; ignore the syscall trace counter
	beq	_Rexit
	nop
	btstq	TIF_NEED_RESCHED, $r1
	bmi	_work_resched	; current->work.need_resched
	nop

_work_notifysig:
	;; deal with pending signals and notify-resume requests

	move.d	$r9, $r10	; do_notify_resume syscall/irq param
	move.d	$sp, $r11	; the regs param
	move.d  $r1, $r12	; the thread_info_flags parameter
	jsr	do_notify_resume
	
	ba _Rexit
	nop

	;; We get here as a sidetrack when we've entered a syscall with the
	;; trace-bit set. We need to call do_syscall_trace and then continue
	;; with the call.
	
_syscall_trace_entry:
	;; PT_r10 in the frame contains -ENOSYS as required, at this point
	
	jsr	do_syscall_trace

	;; now re-enter the syscall code to do the syscall itself
	;; we need to restore $r9 here to contain the wanted syscall, and
	;; the other parameter-bearing registers

	move.d	[$sp+PT_r9], $r9
	move.d	[$sp+PT_orig_r10], $r10  ; PT_r10 is already filled with -ENOSYS.
	move.d	[$sp+PT_r11],      $r11
	move.d	[$sp+PT_r12],      $r12
	move.d	[$sp+PT_r13],      $r13
	move	[$sp+PT_mof],      $mof
	move	[$sp+PT_srp],      $srp
	
	ba	_syscall_traced
	nop
	
	;; resume performs the actual task-switching, by switching stack pointers
	;; input arguments: r10 = prev, r11 = next, r12 = thread offset in task struct
	;; returns old current in r10
	;;
	;; TODO:  see the i386 version. The switch_to which calls resume in our version
	;;        could really be an inline asm of this.

resume:	
	push	$srp		         ; we keep the old/new PC on the stack 
	add.d	$r12, $r10		 ; r10 = current tasks tss
	move	$dccr, [$r10+THREAD_dccr]; save irq enable state
	di

	move	$usp, [$r10+ THREAD_usp] ; save user-mode stackpointer
	
	;; See copy_thread for the reason why register R9 is saved.
	subq	10*4, $sp
	movem	$r9, [$sp]		 ; save non-scratch registers and R9.
	
	move.d	$sp, [$r10+THREAD_ksp]	 ; save the kernel stack pointer for the old task
	move.d	$sp, $r10		 ; return last running task in r10
	and.d   -8192, $r10	         ; get thread_info from stackpointer
	move.d  [$r10+TI_task], $r10     ; get task  
	add.d	$r12, $r11		 ; find the new tasks tss
	move.d	[$r11+THREAD_ksp], $sp	 ; switch into the new stackframe by restoring kernel sp

	movem	[$sp+], $r9		 ; restore non-scratch registers and R9.

	move	[$r11+THREAD_usp], $usp ; restore user-mode stackpointer
	
	move	[$r11+THREAD_dccr], $dccr ; restore irq enable status
	jump	[$sp+]		         ; restore PC

	;; This is the MMU bus fault handler.
	;; It needs to stack the CPU status and overall is different
	;; from the other interrupt handlers.

mmu_bus_fault:
	;; For refills we try to do a quick page table lookup. If it is
	;; a real fault we let the mm subsystem handle it.

	;; the first longword in the sbfs frame was the interrupted PC
	;; which fits nicely with the "IRP" slot in pt_regs normally used to
	;; contain the return address. used by Oops to print kernel errors.
	sbfs	[$sp=$sp-16]	; push the internal CPU status
	push	$dccr
	di
	subq	2*4, $sp
	movem	$r1, [$sp]
	move.d  [R_MMU_CAUSE], $r1
	;; ETRAX 100LX TR89 bugfix: if the second half of an unaligned
	;; write causes a MMU-fault, it will not be restarted correctly.
	;; This could happen if a write crosses a page-boundary and the
	;; second page is not yet COW'ed or even loaded. The workaround
	;; is to clear the unaligned bit in the CPU status record, so
	;; that the CPU will rerun both the first and second halves of
	;; the instruction. This will not have any sideeffects unless
	;; the first half goes to any device or memory that can't be
	;; written twice, and which is mapped through the MMU.
	;;
	;; We only need to do this for writes.
	btstq	8, $r1		   ; Write access?
	bpl	1f
	nop
	move.d	[$sp+16], $r0	   ; Clear unaligned bit in csrinstr
	and.d	~(1<<5), $r0
	move.d	$r0, [$sp+16]
1:	btstq	12, $r1		   ; Refill?
	bpl	2f
	lsrq	24, $r1     ; Get PGD index (bit 24-31)
	move.d  [per_cpu__current_pgd], $r0 ; PGD for the current process
	move.d	[$r0+$r1.d], $r0   ; Get PMD
	beq	2f
	nop
	and.w	PAGE_MASK, $r0	   ; Remove PMD flags
	move.d  [R_MMU_CAUSE], $r1
	lsrq	PAGE_SHIFT, $r1
	and.d	0x7ff, $r1         ; Get PTE index into PGD (bit 13-23)
	move.d	[$r0+$r1.d], $r1   ; Get PTE
	beq	2f
	nop
	;; Store in TLB
	move.d  $r1, [R_TLB_LO]
	;; Return
	movem	[$sp+], $r1
	pop	$dccr
	rbf	[$sp+]		; return by popping the CPU status

2:	; PMD or PTE missing, let the mm subsystem fix it up.
	movem	[$sp+], $r1
	pop	$dccr

	; Ok, not that easy, pass it on to the mm subsystem
	; The MMU status record is now on the stack
	push	$srp		; make a stackframe similar to pt_regs
	push	$dccr
	push	$mof
	di
	subq	14*4, $sp
	movem	$r13, [$sp]
	push	$r10		; dummy orig_r10
	moveq	1, $r10
	push	$r10		; frametype == 1, BUSFAULT frame type

	move.d	$sp, $r10	; pt_regs argument to handle_mmu_bus_fault
		
	jsr	handle_mmu_bus_fault  ; in arch/cris/arch-v10/mm/fault.c

	;; now we need to return through the normal path, we cannot just
	;; do the RBFexit since we might have killed off the running
	;; process due to a SEGV, scheduled due to a page blocking or
	;; whatever.

	moveq	0, $r9		; busfault is equivalent to an irq
		
	ba	ret_from_intr
	nop
		
	;; special handlers for breakpoint and NMI
hwbreakpoint:
	push	$dccr
	di
	push	$r10
	push	$r11
	move.d	[hw_bp_trig_ptr],$r10
	move	$brp,$r11
	move.d	$r11,[$r10+]
	move.d	$r10,[hw_bp_trig_ptr]
1:	pop	$r11
	pop	$r10
	pop	$dccr
	retb
	nop
	
IRQ1_interrupt:
	;; this prologue MUST match the one in irq.h and the struct in ptregs.h!!!
	move	$brp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
	push	$srp
	push	$dccr
	push	$mof
	di
	subq	14*4, $sp
	movem	$r13, [$sp]
	push	$r10		; push orig_r10
	clear.d [$sp=$sp-4]	; frametype == 0, normal frame

	;; If there is a glitch on the NMI pin shorter than ~100ns
	;; (i.e. non-active by the time we get here) then the nmi_pin bit
	;; in R_IRQ_MASK0_RD will already be cleared.  The watchdog_nmi bit
	;; is cleared by us however (when feeding the watchdog), which is why
	;; we use that bit to determine what brought us here.

	move.d	[R_IRQ_MASK0_RD], $r1 ; External NMI or watchdog?
	and.d   (1<<30), $r1
	bne	wdog
	move.d  $sp, $r10
	jsr	handle_nmi
	setf m			; Enable NMI again
	ba	_Rexit		; Return the standard way
	nop
wdog:
#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
;; Check if we're waiting for reset to happen, as signalled by
;; hard_reset_now setting cause_of_death to a magic value.  If so, just
;; get stuck until reset happens.
	.comm	cause_of_death, 4	;; Don't declare this anywhere.
	move.d	[cause_of_death], $r10
	cmp.d	0xbedead, $r10
_killed_by_death:
	beq	_killed_by_death
	nop

;; We'll see this in ksymoops dumps.
Watchdog_bite:

#ifdef CONFIG_ETRAX_WATCHDOG_NICE_DOGGY
       ;; We just restart the watchdog here to be sure we dont get
       ;; hit while printing the watchdogmsg below
       ;; This restart is compatible with the rest of the C-code, so
       ;; the C-code can keep restarting the watchdog after this point.
       ;; The non-NICE_DOGGY code below though, disables the possibility
       ;; to restart since it changes the watchdog key, to avoid any
       ;; buggy loops etc. keeping the watchdog alive after this.
       jsr     reset_watchdog
#else

;; We need to extend the 3.3ms after the NMI at watchdog bite, so we have
;; time for an oops-dump over a 115k2 serial wire.  Another 100ms should do.

;; Change the watchdog key to an arbitrary 3-bit value and restart the
;; watchdog.
#define WD_INIT 2
	moveq	  IO_FIELD (R_WATCHDOG, key, WD_INIT), $r10
	move.d	R_WATCHDOG, $r11

	move.d	$r10, [$r11]
	moveq	  IO_FIELD (R_WATCHDOG, key,				\
			    IO_EXTRACT (R_WATCHDOG, key,		\
					IO_MASK (R_WATCHDOG, key))	\
			    ^ WD_INIT)					\
		| IO_STATE (R_WATCHDOG, enable, start), $r10
	move.d	$r10, [$r11]

#endif
	
;; Note that we don't do "setf m" here (or after two necessary NOPs),
;; since *not* doing that saves us from re-entrancy checks.  We don't want
;; to get here again due to possible subsequent NMIs; we want the watchdog
;; to reset us.

	move.d	_watchdogmsg,$r10
	jsr	printk

	move.d	$sp, $r10
	jsr	watchdog_bite_hook

;; This nop is here so we see the "Watchdog_bite" label in ksymoops dumps
;; rather than "spurious_interrupt".
	nop
;; At this point we drop down into spurious_interrupt, which will do a
;; hard reset.

	.section .rodata,"a"
_watchdogmsg:
	.ascii	"Oops: bitten by watchdog\n\0"
	.previous

#endif /* CONFIG_ETRAX_WATCHDOG and not CONFIG_SVINTO_SIM */

spurious_interrupt:	
	di
	jump hard_reset_now

	;; this handles the case when multiple interrupts arrive at the same time
	;; we jump to the first set interrupt bit in a priority fashion
	;; the hardware will call the unserved interrupts after the handler finishes
	
multiple_interrupt:
	;; this prologue MUST match the one in irq.h and the struct in ptregs.h!!!
	move	$irp,[$sp=$sp-16]; instruction pointer and room for a fake SBFS frame
	push	$srp
	push	$dccr
	push	$mof
	di
	subq	14*4, $sp
	movem	$r13, [$sp]
	push	$r10		; push orig_r10
	clear.d [$sp=$sp-4]	; frametype == 0, normal frame
	
	move.d  $sp, $r10
	jsr	do_multiple_IRQ
	
	jump    ret_from_intr

do_sigtrap:
	;; 
	;; SIGTRAP the process that executed the break instruction.
	;; Make a frame that Rexit in entry.S expects.
	;;
	move	$brp, [$sp=$sp-16]	; Push BRP while faking a cpu status record.
	push	$srp			; Push subroutine return pointer.
	push	$dccr			; Push condition codes.
	push	$mof			; Push multiply overflow reg.
	di				; Need to disable irq's at this point.
	subq	14*4, $sp		; Make room for r0-r13.
	movem	$r13, [$sp]		; Push the r0-r13 registers.
	push	$r10			; Push orig_r10.
	clear.d	[$sp=$sp-4]		; Frametype - this is a normal stackframe.

	movs.w	-8192,$r9		; THREAD_SIZE == 8192
	and.d	$sp, $r9
	move.d  [$r9+TI_task], $r10
	move.d  [$r10+TASK_pid], $r10	; current->pid as arg1. 
	moveq	5, $r11			; SIGTRAP as arg2.
	jsr	sys_kill       
	jump	ret_from_intr		; Use the return routine for interrupts.

gdb_handle_breakpoint:	
	push	$dccr
	push	$r0
#ifdef CONFIG_ETRAX_KGDB
	move	$dccr, $r0		; U-flag not affected by previous insns. 
	btstq	8, $r0			; Test the U-flag.
	bmi	_ugdb_handle_breakpoint	; Go to user mode debugging. 
	nop				; Empty delay slot (cannot pop r0 here). 
	pop	$r0			; Restore r0.
	ba	kgdb_handle_breakpoint	; Go to kernel debugging. 
	pop	$dccr			; Restore dccr in delay slot.
#endif
	
_ugdb_handle_breakpoint:	
	move	$brp, $r0		; Use r0 temporarily for calculation.
	subq	2, $r0			; Set to address of previous instruction.
	move	$r0, $brp
	pop	$r0			; Restore r0. 
	ba	do_sigtrap		; SIGTRAP the offending process. 
	pop	$dccr			; Restore dccr in delay slot.
	
	.global kernel_execve
kernel_execve:
	move.d __NR_execve, $r9
	break 13
	ret
	nop

	.data

hw_bp_trigs:
	.space 64*4
hw_bp_trig_ptr:
	.dword hw_bp_trigs

	.section .rodata,"a"
sys_call_table:	
	.long sys_restart_syscall	/* 0 - old "setup()" system call, used for restarting */
	.long sys_exit
	.long sys_fork
	.long sys_read
	.long sys_write
	.long sys_open		/* 5 */
	.long sys_close
	.long sys_waitpid
	.long sys_creat
	.long sys_link
	.long sys_unlink	/* 10 */
	.long sys_execve
	.long sys_chdir
	.long sys_time
	.long sys_mknod
	.long sys_chmod		/* 15 */
	.long sys_lchown16
	.long sys_ni_syscall	/* old break syscall holder */
	.long sys_stat
	.long sys_lseek
	.long sys_getpid	/* 20 */
	.long sys_mount
	.long sys_oldumount
	.long sys_setuid16
	.long sys_getuid16
	.long sys_stime		/* 25 */
	.long sys_ptrace
	.long sys_alarm
	.long sys_fstat
	.long sys_pause
	.long sys_utime		/* 30 */
	.long sys_ni_syscall	/* old stty syscall holder */
	.long sys_ni_syscall	/* old gtty syscall holder */
	.long sys_access
	.long sys_nice
	.long sys_ni_syscall	/* 35  old ftime syscall holder */
	.long sys_sync
	.long sys_kill
	.long sys_rename
	.long sys_mkdir
	.long sys_rmdir		/* 40 */
	.long sys_dup
	.long sys_pipe
	.long sys_times
	.long sys_ni_syscall	/* old prof syscall holder */
	.long sys_brk		/* 45 */
	.long sys_setgid16
	.long sys_getgid16
	.long sys_signal
	.long sys_geteuid16
	.long sys_getegid16	/* 50 */
	.long sys_acct
	.long sys_umount	/* recycled never used phys( */
	.long sys_ni_syscall	/* old lock syscall holder */
	.long sys_ioctl
	.long sys_fcntl		/* 55 */
	.long sys_ni_syscall	/* old mpx syscall holder */
	.long sys_setpgid
	.long sys_ni_syscall	/* old ulimit syscall holder */
	.long sys_ni_syscall	/* old sys_olduname holder */
	.long sys_umask		/* 60 */
	.long sys_chroot
	.long sys_ustat
	.long sys_dup2
	.long sys_getppid
	.long sys_getpgrp	/* 65 */
	.long sys_setsid
	.long sys_sigaction
	.long sys_sgetmask
	.long sys_ssetmask
	.long sys_setreuid16	/* 70 */
	.long sys_setregid16
	.long sys_sigsuspend
	.long sys_sigpending
	.long sys_sethostname
	.long sys_setrlimit	/* 75 */
	.long sys_old_getrlimit
	.long sys_getrusage
	.long sys_gettimeofday
	.long sys_settimeofday
	.long sys_getgroups16	/* 80 */
	.long sys_setgroups16
	.long sys_select	/* was old_select in Linux/E100 */
	.long sys_symlink
	.long sys_lstat
	.long sys_readlink	/* 85 */
	.long sys_uselib
	.long sys_swapon
	.long sys_reboot
	.long old_readdir
	.long old_mmap		/* 90 */
	.long sys_munmap
	.long sys_truncate
	.long sys_ftruncate
	.long sys_fchmod
	.long sys_fchown16	/* 95 */
	.long sys_getpriority
	.long sys_setpriority
	.long sys_ni_syscall	/* old profil syscall holder */
	.long sys_statfs
	.long sys_fstatfs	/* 100 */
	.long sys_ni_syscall	/* sys_ioperm in i386 */
	.long sys_socketcall
	.long sys_syslog
	.long sys_setitimer
	.long sys_getitimer	/* 105 */
	.long sys_newstat
	.long sys_newlstat
	.long sys_newfstat
	.long sys_ni_syscall	/* old sys_uname holder */
	.long sys_ni_syscall	/* sys_iopl in i386 */
	.long sys_vhangup
	.long sys_ni_syscall	/* old "idle" system call */
	.long sys_ni_syscall	/* vm86old in i386 */
	.long sys_wait4
	.long sys_swapoff	/* 115 */
	.long sys_sysinfo
	.long sys_ipc
	.long sys_fsync
	.long sys_sigreturn
	.long sys_clone		/* 120 */
	.long sys_setdomainname
	.long sys_newuname
	.long sys_ni_syscall	/* sys_modify_ldt */
	.long sys_adjtimex
	.long sys_mprotect	/* 125 */
	.long sys_sigprocmask
	.long sys_ni_syscall	/* old "create_module" */ 
	.long sys_init_module
	.long sys_delete_module
	.long sys_ni_syscall	/* 130:	old "get_kernel_syms" */
	.long sys_quotactl
	.long sys_getpgid
	.long sys_fchdir
	.long sys_bdflush
	.long sys_sysfs		/* 135 */
	.long sys_personality
	.long sys_ni_syscall	/* for afs_syscall */
	.long sys_setfsuid16
	.long sys_setfsgid16
	.long sys_llseek	/* 140 */
	.long sys_getdents
	.long sys_select
	.long sys_flock
	.long sys_msync
	.long sys_readv		/* 145 */
	.long sys_writev
	.long sys_getsid
	.long sys_fdatasync
	.long sys_sysctl
	.long sys_mlock		/* 150 */
	.long sys_munlock
	.long sys_mlockall
	.long sys_munlockall
	.long sys_sched_setparam
	.long sys_sched_getparam	/* 155 */
	.long sys_sched_setscheduler
	.long sys_sched_getscheduler
	.long sys_sched_yield
	.long sys_sched_get_priority_max
	.long sys_sched_get_priority_min	/* 160 */
	.long sys_sched_rr_get_interval
	.long sys_nanosleep
	.long sys_mremap
	.long sys_setresuid16
	.long sys_getresuid16	/* 165 */
	.long sys_ni_syscall	/* sys_vm86 */
	.long sys_ni_syscall	/* Old sys_query_module */
	.long sys_poll
	.long sys_nfsservctl
	.long sys_setresgid16	/* 170 */
	.long sys_getresgid16
	.long sys_prctl
	.long sys_rt_sigreturn
	.long sys_rt_sigaction
	.long sys_rt_sigprocmask	/* 175 */
	.long sys_rt_sigpending
	.long sys_rt_sigtimedwait
	.long sys_rt_sigqueueinfo
	.long sys_rt_sigsuspend
	.long sys_pread64	/* 180 */
	.long sys_pwrite64
	.long sys_chown16
	.long sys_getcwd
	.long sys_capget
	.long sys_capset	/* 185 */
	.long sys_sigaltstack
	.long sys_sendfile
	.long sys_ni_syscall	/* streams1 */
	.long sys_ni_syscall	/* streams2 */
	.long sys_vfork		/* 190 */
	.long sys_getrlimit
	.long sys_mmap2
	.long sys_truncate64
	.long sys_ftruncate64
	.long sys_stat64	/* 195 */
	.long sys_lstat64
	.long sys_fstat64
	.long sys_lchown
	.long sys_getuid
	.long sys_getgid	/* 200 */
	.long sys_geteuid
	.long sys_getegid
	.long sys_setreuid
	.long sys_setregid
	.long sys_getgroups	/* 205 */
	.long sys_setgroups
	.long sys_fchown
	.long sys_setresuid
	.long sys_getresuid
	.long sys_setresgid	/* 210 */
	.long sys_getresgid
	.long sys_chown
	.long sys_setuid
	.long sys_setgid
	.long sys_setfsuid	/* 215 */
	.long sys_setfsgid
	.long sys_pivot_root
	.long sys_mincore
	.long sys_madvise
	.long sys_getdents64	/* 220 */
	.long sys_fcntl64
	.long sys_ni_syscall	/* reserved for TUX */
	.long sys_ni_syscall
	.long sys_gettid
	.long sys_readahead	/* 225 */
	.long sys_setxattr
	.long sys_lsetxattr
	.long sys_fsetxattr
	.long sys_getxattr
	.long sys_lgetxattr	/* 230 */
	.long sys_fgetxattr
	.long sys_listxattr
	.long sys_llistxattr
	.long sys_flistxattr
	.long sys_removexattr	/* 235 */
	.long sys_lremovexattr
	.long sys_fremovexattr
	.long sys_tkill
	.long sys_sendfile64
	.long sys_futex		/* 240 */
	.long sys_sched_setaffinity
	.long sys_sched_getaffinity
	.long sys_ni_syscall	/* sys_set_thread_area */
	.long sys_ni_syscall	/* sys_get_thread_area */
	.long sys_io_setup	/* 245 */
	.long sys_io_destroy
	.long sys_io_getevents
	.long sys_io_submit
	.long sys_io_cancel
	.long sys_fadvise64	/* 250 */
	.long sys_ni_syscall
	.long sys_exit_group
	.long sys_lookup_dcookie
	.long sys_epoll_create
	.long sys_epoll_ctl	/* 255 */
	.long sys_epoll_wait
	.long sys_remap_file_pages
 	.long sys_set_tid_address
 	.long sys_timer_create
 	.long sys_timer_settime		/* 260 */
 	.long sys_timer_gettime
 	.long sys_timer_getoverrun
 	.long sys_timer_delete
 	.long sys_clock_settime
 	.long sys_clock_gettime		/* 265 */
 	.long sys_clock_getres
 	.long sys_clock_nanosleep
	.long sys_statfs64
	.long sys_fstatfs64	
	.long sys_tgkill	/* 270 */
	.long sys_utimes
 	.long sys_fadvise64_64
	.long sys_ni_syscall	/* sys_vserver */
	.long sys_ni_syscall	/* sys_mbind */
	.long sys_ni_syscall	/* 275 sys_get_mempolicy */
	.long sys_ni_syscall	/* sys_set_mempolicy */
	.long sys_mq_open
	.long sys_mq_unlink
	.long sys_mq_timedsend
	.long sys_mq_timedreceive	/* 280 */
	.long sys_mq_notify
	.long sys_mq_getsetattr
	.long sys_ni_syscall		/* reserved for kexec */
	.long sys_waitid
	.long sys_ni_syscall		/* 285 */ /* available */
	.long sys_add_key
	.long sys_request_key
	.long sys_keyctl
	.long sys_ioprio_set
	.long sys_ioprio_get		/* 290 */
	.long sys_inotify_init
	.long sys_inotify_add_watch
	.long sys_inotify_rm_watch
	.long sys_migrate_pages
	.long sys_openat		/* 295 */
	.long sys_mkdirat
	.long sys_mknodat
	.long sys_fchownat
	.long sys_futimesat
	.long sys_fstatat64		/* 300 */
	.long sys_unlinkat
	.long sys_renameat
	.long sys_linkat
	.long sys_symlinkat
	.long sys_readlinkat		/* 305 */
	.long sys_fchmodat
	.long sys_faccessat
	.long sys_pselect6
	.long sys_ppoll
	.long sys_unshare		/* 310 */
	.long sys_set_robust_list
	.long sys_get_robust_list
	.long sys_splice
	.long sys_sync_file_range
	.long sys_tee			/* 315 */
	.long sys_vmsplice
	.long sys_move_pages
	.long sys_getcpu
	.long sys_epoll_pwait
	.long sys_utimensat		/* 320 */
	.long sys_signalfd
	.long sys_ni_syscall
	.long sys_eventfd
	.long sys_fallocate

        /*
         * NOTE!! This doesn't have to be exact - we just have
         * to make sure we have _enough_ of the "sys_ni_syscall"
         * entries. Don't panic if you notice that this hasn't
         * been shrunk every time we add a new system call.
         */

	.rept NR_syscalls-(.-sys_call_table)/4
		.long sys_ni_syscall
	.endr