entry.s

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/* -*- mode: asm -*-
 *
 *  linux/arch/m68k/kernel/entry.S
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file README.legal in the main directory of this archive
 * for more details.
 *
 * Linux/m68k support by Hamish Macdonald
 *
 * 68060 fixes by Jesper Skov
 *
 */

/*
 * entry.S  contains the system-call and fault low-level handling routines.
 * This also contains the timer-interrupt handler, as well as all interrupts
 * and faults that can result in a task-switch.
 *
 * NOTE: This code handles signal-recognition, which happens every time
 * after a timer-interrupt and after each system call.
 *
 */

/*
 * 12/03/96 Jes: Currently we only support m68k single-cpu systems, so
 *               all pointers that used to be 'current' are now entry
 *               number 0 in the 'current_set' list.
 *
 *  6/05/00 RZ:	 addedd writeback completion after return from sighandler
 *		 for 68040
 */

#include <linux/sys.h>
#include <linux/config.h>
#include <linux/linkage.h>
#include <asm/entry.h>
#include <asm/errno.h>
#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/traps.h>

#include "m68k_defs.h"

.globl SYMBOL_NAME(system_call), SYMBOL_NAME(buserr), SYMBOL_NAME(trap)
.globl SYMBOL_NAME(resume), SYMBOL_NAME(ret_from_exception)
.globl SYMBOL_NAME(ret_from_signal)
.globl SYMBOL_NAME(inthandler), SYMBOL_NAME(sys_call_table)
.globl SYMBOL_NAME(sys_fork), SYMBOL_NAME(sys_clone), SYMBOL_NAME(sys_vfork)
.globl SYMBOL_NAME(ret_from_interrupt), SYMBOL_NAME(bad_interrupt)

.text
ENTRY(buserr)
	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(buserr_c)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)

ENTRY(trap)
	SAVE_ALL_INT
	GET_CURRENT(%d0)
	movel	%sp,%sp@- 		| stack frame pointer argument
	bsrl	SYMBOL_NAME(trap_c)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)

ENTRY(reschedule)
	| save top of frame
	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)

	pea	SYMBOL_NAME(ret_from_exception)
	jmp	SYMBOL_NAME(schedule)

	| After a fork we jump here directly from resume,
	| so that %d1 contains the previous task
	| Theoretically only needed on SMP, but let's watch
	| what happens in schedule_tail() in future...
ENTRY(ret_from_fork)
	movel	%d1,%sp@-
	jsr	SYMBOL_NAME(schedule_tail)
	addql	#4,%sp
	jra	SYMBOL_NAME(ret_from_exception)

badsys:
	movel	#-ENOSYS,%sp@(PT_D0)
	jra	SYMBOL_NAME(ret_from_exception)

do_trace:
	movel	#-ENOSYS,%sp@(PT_D0)	| needed for strace
	subql	#4,%sp
	SAVE_SWITCH_STACK
	jbsr	SYMBOL_NAME(syscall_trace)
	RESTORE_SWITCH_STACK
	addql	#4,%sp
	movel	%sp@(PT_ORIG_D0),%d1
	movel	#-ENOSYS,%d0
	cmpl	#NR_syscalls,%d1
	jcc	1f
	jbsr	@(SYMBOL_NAME(sys_call_table),%d1:l:4)@(0)
1:	movel	%d0,%sp@(PT_D0)		| save the return value
	subql	#4,%sp			| dummy return address
	SAVE_SWITCH_STACK
	jbsr	SYMBOL_NAME(syscall_trace)

SYMBOL_NAME_LABEL(ret_from_signal)
	RESTORE_SWITCH_STACK 
	addql	#4,%sp
/* on 68040 complete pending writebacks if any */	
#ifdef CONFIG_M68040
	bfextu	%sp@(PT_VECTOR){#0,#4},%d0  
	subql	#7,%d0				| bus error frame ?
	jbne	1f
	movel	%sp,%sp@-
	jbsr	SYMBOL_NAME(berr_040cleanup)
	addql	#4,%sp
1:	
#endif	
	jra	SYMBOL_NAME(ret_from_exception)

ENTRY(system_call)
	SAVE_ALL_SYS

	GET_CURRENT(%d1)
	| save top of frame
	movel	%sp,%curptr@(TASK_THREAD+THREAD_ESP0)

	btst	#PT_TRACESYS_BIT,%curptr@(TASK_PTRACE+PT_TRACESYS_OFF)
	jne	do_trace
	cmpl	#NR_syscalls,%d0
	jcc	badsys
	jbsr	@(SYMBOL_NAME(sys_call_table),%d0:l:4)@(0)
	movel	%d0,%sp@(PT_D0)		| save the return value

SYMBOL_NAME_LABEL(ret_from_exception)
	btst	#5,%sp@(PT_SR)		| check if returning to kernel
	bnes	2f			| if so, skip resched, signals
	| only allow interrupts when we are really the last one on the
	| kernel stack, otherwise stack overflow can occur during
	| heavy interupt load
	andw	#ALLOWINT,%sr
	tstl	%curptr@(TASK_NEEDRESCHED)
	jne	SYMBOL_NAME(reschedule)
#if 0
	cmpl	#SYMBOL_NAME(task),%curptr	| task[0] cannot have signals
	jeq	2f
#endif
					| check for delayed trace
	bclr	#PT_DTRACE_BIT,%curptr@(TASK_PTRACE+PT_DTRACE_OFF)
	jne	do_delayed_trace
5:
	tstl	%curptr@(TASK_STATE)	| state
	jne	SYMBOL_NAME(reschedule)

	tstl	%curptr@(TASK_SIGPENDING)
	jne	Lsignal_return
2:	RESTORE_ALL

Lsignal_return:
	subql	#4,%sp			| dummy return address
	SAVE_SWITCH_STACK
	pea	%sp@(SWITCH_STACK_SIZE)
	clrl	%sp@-
	bsrl	SYMBOL_NAME(do_signal)
	addql	#8,%sp
	RESTORE_SWITCH_STACK
	addql	#4,%sp
	RESTORE_ALL

do_delayed_trace:
	bclr	#7,%sp@(PT_SR)		| clear trace bit in SR
	pea	1			| send SIGTRAP
	movel	%curptr,%sp@-
	pea	LSIGTRAP
	jbsr	SYMBOL_NAME(send_sig)
	addql	#8,%sp
	addql	#4,%sp
	jra	5b


#if 0
#if CONFIG_AMIGA
SYMBOL_NAME_LABEL(ami_inthandler)
	addql	#1,SYMBOL_NAME(irq_stat)+8	| local_irq_count
	SAVE_ALL_INT
	GET_CURRENT(%d0)

	bfextu	%sp@(PT_VECTOR){#4,#12},%d0
	movel	%d0,%a0
	addql	#1,%a0@(SYMBOL_NAME(kstat)+STAT_IRQ-VECOFF(VEC_SPUR))
	movel	%a0@(SYMBOL_NAME(autoirq_list)-VECOFF(VEC_SPUR)),%a0

| amiga vector int handler get the req mask instead of irq vector
	lea	CUSTOMBASE,%a1
	movew	%a1@(C_INTREQR),%d0
	andw	%a1@(C_INTENAR),%d0

| prepare stack (push frame pointer, dev_id & req mask)
	pea	%sp@
	movel	%a0@(IRQ_DEVID),%sp@-
	movel	%d0,%sp@-
	pea	%pc@(SYMBOL_NAME(ret_from_interrupt):w)
	jbra	@(IRQ_HANDLER,%a0)@(0)

ENTRY(nmi_handler)
	rte
#endif
#endif

/*
** This is the main interrupt handler, responsible for calling process_int()
*/
SYMBOL_NAME_LABEL(inthandler)
	SAVE_ALL_INT
	GET_CURRENT(%d0)
	addql	#1,SYMBOL_NAME(irq_stat)+8	| local_irq_count
					|  put exception # in d0
	bfextu %sp@(PT_VECTOR){#4,#10},%d0

	movel	%sp,%sp@-
	movel	%d0,%sp@- 		|  put vector # on stack
#if defined(MACH_Q40_ONLY) && defined(CONFIG_BLK_DEV_FD)
	btstb	#4,0xff000000	| Q40 floppy needs very special treatment ...
	jbeq	1f
	btstb	#3,0xff000004		
	jbeq	1f
	jbsr	SYMBOL_NAME(floppy_hardint)
	jbra	3f
1:
#endif		
	jbsr	SYMBOL_NAME(process_int)|  process the IRQ
3:     	addql	#8,%sp			|  pop parameters off stack

SYMBOL_NAME_LABEL(ret_from_interrupt)
	subql	#1,SYMBOL_NAME(irq_stat)+8	| local_irq_count
	jeq	1f
2:
	RESTORE_ALL
1:
#if 1
	bfextu  %sp@(PT_SR){#5,#3},%d0	| Check for nested interrupt.
#if MAX_NOINT_IPL > 0
	cmpiw	#MAX_NOINT_IPL,%d0
#endif
	jhi	2b
#endif
	/* check if we need to do software interrupts */

	movel	SYMBOL_NAME(irq_stat),%d0	| softirq_active
	andl	SYMBOL_NAME(irq_stat)+4,%d0	| softirq_mask
	jeq	SYMBOL_NAME(ret_from_exception)

	pea	SYMBOL_NAME(ret_from_exception)
	jra	SYMBOL_NAME(do_softirq)


/* Handler for uninitialized and spurious interrupts */

SYMBOL_NAME_LABEL(bad_interrupt)
	addql	#1,SYMBOL_NAME(num_spurious)
	rte

ENTRY(sys_fork)
	SAVE_SWITCH_STACK	
	pea	%sp@(SWITCH_STACK_SIZE)
	jbsr	SYMBOL_NAME(m68k_fork)
	addql	#4,%sp
	RESTORE_SWITCH_STACK
	rts

ENTRY(sys_clone)
	SAVE_SWITCH_STACK
	pea	%sp@(SWITCH_STACK_SIZE)
	jbsr	SYMBOL_NAME(m68k_clone)
	addql	#4,%sp
	RESTORE_SWITCH_STACK
	rts

ENTRY(sys_vfork)
	SAVE_SWITCH_STACK	
	pea	%sp@(SWITCH_STACK_SIZE)
	jbsr	SYMBOL_NAME(m68k_vfork)
	addql	#4,%sp
	RESTORE_SWITCH_STACK
	rts

ENTRY(sys_sigsuspend)
	SAVE_SWITCH_STACK
	pea	%sp@(SWITCH_STACK_SIZE)
	jbsr	SYMBOL_NAME(do_sigsuspend)
	addql	#4,%sp
	RESTORE_SWITCH_STACK
	rts

ENTRY(sys_rt_sigsuspend)
	SAVE_SWITCH_STACK
	pea	%sp@(SWITCH_STACK_SIZE)
	jbsr	SYMBOL_NAME(do_rt_sigsuspend)
	addql	#4,%sp
	RESTORE_SWITCH_STACK
	rts

ENTRY(sys_sigreturn)
	SAVE_SWITCH_STACK
	jbsr	SYMBOL_NAME(do_sigreturn)
	RESTORE_SWITCH_STACK
	rts

ENTRY(sys_rt_sigreturn)
	SAVE_SWITCH_STACK
	jbsr	SYMBOL_NAME(do_rt_sigreturn)
	RESTORE_SWITCH_STACK
	rts

SYMBOL_NAME_LABEL(resume)
	/*
	 * Beware - when entering resume, prev (the current task) is
	 * in a0, next (the new task) is in a1,so don't change these
	 * registers until their contents are no longer needed.
	 */

	/* save sr */
	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)