/* SPDX-License-Identifier: GPL-2.0-or-later
 *
 *  entry.S -- non-mmu 68000 interrupt and exception entry points
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * Linux/m68k support by Hamish Macdonald
 */

#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/unistd.h>
#include <asm/errno.h>
#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/asm-offsets.h>
#include <asm/entry.h>

.text

.globl system_call
.globl resume
.globl ret_from_exception
.globl sys_call_table
.globl bad_interrupt
.globl inthandler1
.globl inthandler2
.globl inthandler3
.globl inthandler4
.globl inthandler5
.globl inthandler6
.globl inthandler7

badsys:
        movel   #-ENOSYS,%sp@(PT_OFF_D0)
        jra     ret_from_exception

do_trace:
        movel   #-ENOSYS,%sp@(PT_OFF_D0) /* needed for strace*/
        subql   #4,%sp
        SAVE_SWITCH_STACK
        jbsr    syscall_trace_enter
        RESTORE_SWITCH_STACK
        addql   #4,%sp
        addql   #1,%d0
        jeq     ret_from_exception
        movel   %sp@(PT_OFF_ORIG_D0),%d1
        movel   #-ENOSYS,%d0
        cmpl    #NR_syscalls,%d1
        jcc     1f
        lsl     #2,%d1
        lea     sys_call_table, %a0
        jbsr    %a0@(%d1)

1:      movel   %d0,%sp@(PT_OFF_D0)     /* save the return value */
        subql   #4,%sp                  /* dummy return address */
        SAVE_SWITCH_STACK
        jbsr    syscall_trace_leave
        RESTORE_SWITCH_STACK
        addql   #4,%sp
        jra     ret_from_exception

ENTRY(system_call)
        SAVE_ALL_SYS

        /* save top of frame*/
        pea     %sp@
        jbsr    set_esp0
        addql   #4,%sp

        movel   %sp@(PT_OFF_ORIG_D0),%d0

        movel   %sp,%d1                 /* get thread_info pointer */
        andl    #-THREAD_SIZE,%d1
        movel   %d1,%a2
        btst    #(TIF_SYSCALL_TRACE%8),%a2@(TINFO_FLAGS+(31-TIF_SYSCALL_TRACE)/8)
        jne     do_trace
        cmpl    #NR_syscalls,%d0
        jcc     badsys
        lsl     #2,%d0
        lea     sys_call_table,%a0
        movel   %a0@(%d0), %a0
        jbsr    %a0@
        movel   %d0,%sp@(PT_OFF_D0)     /* save the return value*/

ret_from_exception:
        btst    #5,%sp@(PT_OFF_SR)      /* check if returning to kernel*/
        jeq     Luser_return            /* if so, skip resched, signals*/

Lkernel_return:
        RESTORE_ALL

Luser_return:
        /* 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

        movel   %sp,%d1                 /* get thread_info pointer */
        andl    #-THREAD_SIZE,%d1
        movel   %d1,%a2
1:
        move    %a2@(TINFO_FLAGS),%d1   /* thread_info->flags */
        jne     Lwork_to_do
        RESTORE_ALL

Lwork_to_do:
        movel   %a2@(TINFO_FLAGS),%d1   /* thread_info->flags */
        btst    #TIF_NEED_RESCHED,%d1
        jne     reschedule

Lsignal_return:
        subql   #4,%sp                  /* dummy return address*/
        SAVE_SWITCH_STACK
        pea     %sp@(SWITCH_STACK_SIZE)
        bsrw    do_notify_resume
        addql   #4,%sp
        RESTORE_SWITCH_STACK
        addql   #4,%sp
        jra     1b

/*
 * This is the main interrupt handler, responsible for calling process_int()
 */
inthandler1:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #65,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler2:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #66,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler3:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #67,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler4:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #68,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler5:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #69,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler6:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #70,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler7:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   #71,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

inthandler:
        SAVE_ALL_INT
        movew   %sp@(PT_OFF_FORMATVEC), %d0
        and     #0x3ff, %d0

        movel   %sp,%sp@-
        movel   %d0,%sp@-               /*  put vector # on stack*/
        jbsr    process_int             /*  process the IRQ*/
3:      addql   #8,%sp                  /*  pop parameters off stack*/
        bra     ret_from_exception

/*
 * Handler for uninitialized and spurious interrupts.
 */
ENTRY(bad_interrupt)
        addql   #1,irq_err_count
        rte

/*
 * 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.
 */
ENTRY(resume)
        movel   %a0,%d1                         /* save prev thread in d1 */
        movew   %sr,%a0@(TASK_THREAD+THREAD_SR) /* save sr */
        SAVE_SWITCH_STACK
        movel   %sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack */
        movel   %usp,%a3                        /* save usp */
        movel   %a3,%a0@(TASK_THREAD+THREAD_USP)

        movel   %a1@(TASK_THREAD+THREAD_USP),%a3 /* restore user stack */
        movel   %a3,%usp
        movel   %a1@(TASK_THREAD+THREAD_KSP),%sp /* restore new thread stack */
        RESTORE_SWITCH_STACK
        movew   %a1@(TASK_THREAD+THREAD_SR),%sr /* restore thread status reg */
        rts