/* -*- 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/linkage.h>
#include <asm/entry.h>
#include <asm/errno.h>
#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/traps.h>
#include <asm/unistd.h>
#include <asm/asm-offsets.h>
.globl system_call, buserr, trap, resume
.globl sys_call_table
.globl sys_fork, sys_clone, sys_vfork
.globl ret_from_interrupt, bad_interrupt
.globl auto_irqhandler_fixup
.globl user_irqvec_fixup
.text
ENTRY(buserr)
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %sp,%sp@- | stack frame pointer argument
bsrl buserr_c
addql #4,%sp
jra .Lret_from_exception
ENTRY(trap)
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %sp,%sp@- | stack frame pointer argument
bsrl trap_c
addql #4,%sp
jra .Lret_from_exception
| After a fork we jump here directly from resume,
| so that %d1 contains the previous task
| schedule_tail now used regardless of CONFIG_SMP
ENTRY(ret_from_fork)
movel %d1,%sp@-
jsr schedule_tail
addql #4,%sp
jra .Lret_from_exception
do_trace_entry:
movel #-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
subql #4,%sp
SAVE_SWITCH_STACK
jbsr syscall_trace
RESTORE_SWITCH_STACK
addql #4,%sp
movel %sp@(PT_OFF_ORIG_D0),%d0
cmpl #NR_syscalls,%d0
jcs syscall
badsys:
movel #-ENOSYS,%sp@(PT_OFF_D0)
jra ret_from_syscall
do_trace_exit:
subql #4,%sp
SAVE_SWITCH_STACK
jbsr syscall_trace
RESTORE_SWITCH_STACK
addql #4,%sp
jra .Lret_from_exception
ENTRY(ret_from_signal)
movel %curptr@(TASK_STACK),%a1
tstb %a1@(TINFO_FLAGS+2)
jge 1f
jbsr syscall_trace
1: RESTORE_SWITCH_STACK
addql #4,%sp
/* on 68040 complete pending writebacks if any */
#ifdef CONFIG_M68040
bfextu %sp@(PT_OFF_FORMATVEC){#0,#4},%d0
subql #7,%d0 | bus error frame ?
jbne 1f
movel %sp,%sp@-
jbsr berr_040cleanup
addql #4,%sp
1:
#endif
jra .Lret_from_exception
ENTRY(system_call)
SAVE_ALL_SYS
GET_CURRENT(%d1)
movel %d1,%a1
| save top of frame
movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
| syscall trace?
tstb %a1@(TINFO_FLAGS+2)
jmi do_trace_entry
cmpl #NR_syscalls,%d0
jcc badsys
syscall:
jbsr @(sys_call_table,%d0:l:4)@(0)
movel %d0,%sp@(PT_OFF_D0) | save the return value
ret_from_syscall:
|oriw #0x0700,%sr
movel %curptr@(TASK_STACK),%a1
movew %a1@(TINFO_FLAGS+2),%d0
jne syscall_exit_work
1: RESTORE_ALL
syscall_exit_work:
btst #5,%sp@(PT_OFF_SR) | check if returning to kernel
bnes 1b | if so, skip resched, signals
lslw #1,%d0
jcs do_trace_exit
jmi do_delayed_trace
lslw #8,%d0
jmi do_signal_return
pea resume_userspace
jra schedule
ENTRY(ret_from_exception)
.Lret_from_exception:
btst #5,%sp@(PT_OFF_SR) | check if returning to kernel
bnes 1f | 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 interrupt load
andw #ALLOWINT,%sr
resume_userspace:
movel %curptr@(TASK_STACK),%a1
moveb %a1@(TINFO_FLAGS+3),%d0
jne exit_work
1: RESTORE_ALL
exit_work:
| save top of frame
movel %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
lslb #1,%d0
jmi do_signal_return
pea resume_userspace
jra schedule
do_signal_return:
|andw #ALLOWINT,%sr
subql #4,%sp | dummy return address
SAVE_SWITCH_STACK
pea %sp@(SWITCH_STACK_SIZE)
bsrl do_signal
addql #4,%sp
RESTORE_SWITCH_STACK
addql #4,%sp
jbra resume_userspace
do_delayed_trace:
bclr #7,%sp@(PT_OFF_SR) | clear trace bit in SR
pea 1 | send SIGTRAP
movel %curptr,%sp@-
pea LSIGTRAP
jbsr send_sig
addql #8,%sp
addql #4,%sp
jbra resume_userspace
/* This is the main interrupt handler for autovector interrupts */
ENTRY(auto_inthandler)
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %d0,%a1
addqb #1,%a1@(TINFO_PREEMPT+1)
| put exception # in d0
bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
subw #VEC_SPUR,%d0
movel %sp,%sp@-
movel %d0,%sp@- | put vector # on stack
auto_irqhandler_fixup = . + 2
jsr do_IRQ | process the IRQ
addql #8,%sp | pop parameters off stack
ret_from_interrupt:
movel %curptr@(TASK_STACK),%a1
subqb #1,%a1@(TINFO_PREEMPT+1)
jeq ret_from_last_interrupt
2: RESTORE_ALL
ALIGN
ret_from_last_interrupt:
moveq #(~ALLOWINT>>8)&0xff,%d0
andb %sp@(PT_OFF_SR),%d0
jne 2b
/* check if we need to do software interrupts */
tstl irq_stat+CPUSTAT_SOFTIRQ_PENDING
jeq .Lret_from_exception
pea ret_from_exception
jra do_softirq
/* Handler for user defined interrupt vectors */
ENTRY(user_inthandler)
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %d0,%a1
addqb #1,%a1@(TINFO_PREEMPT+1)
| put exception # in d0
bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0
user_irqvec_fixup = . + 2
subw #VEC_USER,%d0
movel %sp,%sp@-
movel %d0,%sp@- | put vector # on stack
jsr do_IRQ | process the IRQ
addql #8,%sp | pop parameters off stack
movel %curptr@(TASK_STACK),%a1
subqb #1,%a1@(TINFO_PREEMPT+1)
jeq ret_from_last_interrupt
RESTORE_ALL
/* Handler for uninitialized and spurious interrupts */
ENTRY(bad_inthandler)
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %d0,%a1
addqb #1,%a1@(TINFO_PREEMPT+1)
movel %sp,%sp@-
jsr handle_badint
addql #4,%sp
movel %curptr@(TASK_STACK),%a1
subqb #1,%a1@(TINFO_PREEMPT+1)
jeq ret_from_last_interrupt
RESTORE_ALL
ENTRY(sys_fork)
SAVE_SWITCH_STACK
pea %sp@(SWITCH_STACK_SIZE)
jbsr m68k_fork
addql #4,%sp
RESTORE_SWITCH_STACK
rts
ENTRY(sys_clone)
SAVE_SWITCH_STACK
pea %sp@(SWITCH_STACK_SIZE)
jbsr m68k_clone
addql #4,%sp
RESTORE_SWITCH_STACK
rts
ENTRY(sys_vfork)
SAVE_SWITCH_STACK
pea %sp@(SWITCH_STACK_SIZE)
jbsr m68k_vfork
addql #4,%sp
RESTORE_SWITCH_STACK
rts
ENTRY(sys_sigreturn)
SAVE_SWITCH_STACK
jbsr do_sigreturn
RESTORE_SWITCH_STACK
rts
ENTRY(sys_rt_sigreturn)
SAVE_SWITCH_STACK
jbsr do_rt_sigreturn
RESTORE_SWITCH_STACK
rts
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)
/* save fs (sfc,%dfc) (may be pointing to kernel memory) */
movec %sfc,%d0
movew %d0,%a0@(TASK_THREAD+THREAD_FS)
/* save usp */
/* it is better to use a movel here instead of a movew 8*) */
movec %usp,%d0
movel %d0,%a0@(TASK_THREAD+THREAD_USP)
/* save non-scratch registers on stack */
SAVE_SWITCH_STACK
/* save current kernel stack pointer */
movel %sp,%a0@(TASK_THREAD+THREAD_KSP)
/* save floating point context */
#ifndef CONFIG_M68KFPU_EMU_ONLY
#ifdef CONFIG_M68KFPU_EMU
tstl m68k_fputype
jeq 3f
#endif
fsave %a0@(TASK_THREAD+THREAD_FPSTATE)
#if defined(CONFIG_M68060)
#if !defined(CPU_M68060_ONLY)
btst #3,m68k_cputype+3
beqs 1f
#endif
/* The 060 FPU keeps status in bits 15-8 of the first longword */
tstb %a0@(TASK_THREAD+THREAD_FPSTATE+2)
jeq 3f
#if !defined(CPU_M68060_ONLY)
jra 2f
#endif
#endif /* CONFIG_M68060 */
#if !defined(CPU_M68060_ONLY)
1: tstb %a0@(TASK_THREAD+THREAD_FPSTATE)
jeq 3f
#endif
2: fmovemx %fp0-%fp7,%a0@(TASK_THREAD+THREAD_FPREG)
fmoveml %fpcr/%fpsr/%fpiar,%a0@(TASK_THREAD+THREAD_FPCNTL)
3:
#endif /* CONFIG_M68KFPU_EMU_ONLY */
/* Return previous task in %d1 */
movel %curptr,%d1
/* switch to new task (a1 contains new task) */
movel %a1,%curptr
/* restore floating point context */
#ifndef CONFIG_M68KFPU_EMU_ONLY
#ifdef CONFIG_M68KFPU_EMU
tstl m68k_fputype
jeq 4f
#endif
#if defined(CONFIG_M68060)
#if !defined(CPU_M68060_ONLY)
btst #3,m68k_cputype+3
beqs 1f
#endif
/* The 060 FPU keeps status in bits 15-8 of the first longword */
tstb %a1@(TASK_THREAD+THREAD_FPSTATE+2)
jeq 3f
#if !defined(CPU_M68060_ONLY)
jra 2f
#endif
#endif /* CONFIG_M68060 */
#if !defined(CPU_M68060_ONLY)
1: tstb %a1@(TASK_THREAD+THREAD_FPSTATE)
jeq 3f
#endif
2: fmovemx %a1@(TASK_THREAD+THREAD_FPREG),%fp0-%fp7
fmoveml %a1@(TASK_THREAD+THREAD_FPCNTL),%fpcr/%fpsr/%fpiar
3: frestore %a1@(TASK_THREAD+THREAD_FPSTATE)
4:
#endif /* CONFIG_M68KFPU_EMU_ONLY */
/* restore the kernel stack pointer */
movel %a1@(TASK_THREAD+THREAD_KSP),%sp
/* restore non-scratch registers */
RESTORE_SWITCH_STACK
/* restore user stack pointer */
movel %a1@(TASK_THREAD+THREAD_USP),%a0
movel %a0,%usp
/* restore fs (sfc,%dfc) */
movew %a1@(TASK_THREAD+THREAD_FS),%a0
movec %a0,%sfc
movec %a0,%dfc
/* restore status register */
movew %a1@(TASK_THREAD+THREAD_SR),%sr
rts