/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994 - 2000, 2001, 2003 Ralf Baechle
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2001 MIPS Technologies, Inc.
 */

#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/compiler.h>
#include <asm/irqflags.h>
#include <asm/regdef.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>
#include <asm/isadep.h>
#include <asm/thread_info.h>
#include <asm/war.h>

#ifndef CONFIG_PREEMPT
#define resume_kernel   restore_all
#else
#define __ret_from_irq  ret_from_exception
#endif

        .text
        .align  5
#ifndef CONFIG_PREEMPT
FEXPORT(ret_from_exception)
        local_irq_disable                       # preempt stop
        b       __ret_from_irq
#endif
FEXPORT(ret_from_irq)
        LONG_S  s0, TI_REGS($28)
FEXPORT(__ret_from_irq)
/*
 * We can be coming here from a syscall done in the kernel space,
 * e.g. a failed kernel_execve().
 */
resume_userspace_check:
        LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
        andi    t0, t0, KU_USER
        beqz    t0, resume_kernel

resume_userspace:
        local_irq_disable               # make sure we dont miss an
                                        # interrupt setting need_resched
                                        # between sampling and return
        LONG_L  a2, TI_FLAGS($28)       # current->work
        andi    t0, a2, _TIF_WORK_MASK  # (ignoring syscall_trace)
        bnez    t0, work_pending
        j       restore_all

#ifdef CONFIG_PREEMPT
resume_kernel:
        local_irq_disable
        lw      t0, TI_PRE_COUNT($28)
        bnez    t0, restore_all
need_resched:
        LONG_L  t0, TI_FLAGS($28)
        andi    t1, t0, _TIF_NEED_RESCHED
        beqz    t1, restore_all
        LONG_L  t0, PT_STATUS(sp)               # Interrupts off?
        andi    t0, 1
        beqz    t0, restore_all
        jal     preempt_schedule_irq
        b       need_resched
#endif

FEXPORT(ret_from_kernel_thread)
        jal     schedule_tail           # a0 = struct task_struct *prev
        move    a0, s1
        jal     s0
        j       syscall_exit

FEXPORT(ret_from_fork)
        jal     schedule_tail           # a0 = struct task_struct *prev

FEXPORT(syscall_exit)
#ifdef CONFIG_DEBUG_RSEQ
        move    a0, sp
        jal     rseq_syscall
#endif
        local_irq_disable               # make sure need_resched and
                                        # signals dont change between
                                        # sampling and return
        LONG_L  a2, TI_FLAGS($28)       # current->work
        li      t0, _TIF_ALLWORK_MASK
        and     t0, a2, t0
        bnez    t0, syscall_exit_work

restore_all:                            # restore full frame
        .set    noat
        RESTORE_TEMP
        RESTORE_AT
        RESTORE_STATIC
restore_partial:                # restore partial frame
#ifdef CONFIG_TRACE_IRQFLAGS
        SAVE_STATIC
        SAVE_AT
        SAVE_TEMP
        LONG_L  v0, PT_STATUS(sp)
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
        and     v0, ST0_IEP
#else
        and     v0, ST0_IE
#endif
        beqz    v0, 1f
        jal     trace_hardirqs_on
        b       2f
1:      jal     trace_hardirqs_off
2:
        RESTORE_TEMP
        RESTORE_AT
        RESTORE_STATIC
#endif
        RESTORE_SOME
        RESTORE_SP_AND_RET
        .set    at

work_pending:
        andi    t0, a2, _TIF_NEED_RESCHED # a2 is preloaded with TI_FLAGS
        beqz    t0, work_notifysig
work_resched:
        TRACE_IRQS_OFF
        jal     schedule

        local_irq_disable               # make sure need_resched and
                                        # signals dont change between
                                        # sampling and return
        LONG_L  a2, TI_FLAGS($28)
        andi    t0, a2, _TIF_WORK_MASK  # is there any work to be done
                                        # other than syscall tracing?
        beqz    t0, restore_all
        andi    t0, a2, _TIF_NEED_RESCHED
        bnez    t0, work_resched

work_notifysig:                         # deal with pending signals and
                                        # notify-resume requests
        move    a0, sp
        li      a1, 0
        jal     do_notify_resume        # a2 already loaded
        j       resume_userspace_check

FEXPORT(syscall_exit_partial)
#ifdef CONFIG_DEBUG_RSEQ
        move    a0, sp
        jal     rseq_syscall
#endif
        local_irq_disable               # make sure need_resched doesn't
                                        # change between and return
        LONG_L  a2, TI_FLAGS($28)       # current->work
        li      t0, _TIF_ALLWORK_MASK
        and     t0, a2
        beqz    t0, restore_partial
        SAVE_STATIC
syscall_exit_work:
        LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
        andi    t0, t0, KU_USER
        beqz    t0, resume_kernel
        li      t0, _TIF_WORK_SYSCALL_EXIT
        and     t0, a2                  # a2 is preloaded with TI_FLAGS
        beqz    t0, work_pending        # trace bit set?
        local_irq_enable                # could let syscall_trace_leave()
                                        # call schedule() instead
        TRACE_IRQS_ON
        move    a0, sp
        jal     syscall_trace_leave
        b       resume_userspace

#if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) || \
    defined(CONFIG_MIPS_MT)

/*
 * MIPS32R2 Instruction Hazard Barrier - must be called
 *
 * For C code use the inline version named instruction_hazard().
 */
LEAF(mips_ihb)
        .set    MIPS_ISA_LEVEL_RAW
        jr.hb   ra
        nop
        END(mips_ihb)

#endif /* CONFIG_CPU_MIPSR2 or CONFIG_CPU_MIPSR6 or CONFIG_MIPS_MT */