arch/mips/kernel/entry.S

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994 - 2000, 2001, 2003 Ralf Baechle
   7  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   8  * Copyright (C) 2001 MIPS Technologies, Inc.
   9  */
  10
  11 #include <asm/asm.h>
  12 #include <asm/asmmacro.h>
  13 #include <asm/regdef.h>
  14 #include <asm/mipsregs.h>
  15 #include <asm/stackframe.h>
  16 #include <asm/isadep.h>
  17 #include <asm/thread_info.h>
  18 #include <asm/war.h>
  19
  20 #ifndef CONFIG_PREEMPT
  21 #define resume_kernel   restore_all
  22 #else
  23 #define __ret_from_irq  ret_from_exception
  24 #endif
  25
  26         .text
  27         .align  5
  28 #ifndef CONFIG_PREEMPT
  29 FEXPORT(ret_from_exception)
  30         local_irq_disable                       # preempt stop
  31         b       __ret_from_irq
  32 #endif
  33 FEXPORT(ret_from_irq)
  34         LONG_S  s0, TI_REGS($28)
  35 FEXPORT(__ret_from_irq)
  36 /*
  37  * We can be coming here from a syscall done in the kernel space,
  38  * e.g. a failed kernel_execve().
  39  */
  40 resume_userspace_check:
  41         LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
  42         andi    t0, t0, KU_USER
  43         beqz    t0, resume_kernel
  44
  45 resume_userspace:
  46         local_irq_disable               # make sure we dont miss an
  47                                         # interrupt setting need_resched
  48                                         # between sampling and return
  49         LONG_L  a2, TI_FLAGS($28)       # current->work
  50         andi    t0, a2, _TIF_WORK_MASK  # (ignoring syscall_trace)
  51         bnez    t0, work_pending
  52         j       restore_all
  53
  54 #ifdef CONFIG_PREEMPT
  55 resume_kernel:
  56         local_irq_disable
  57         lw      t0, TI_PRE_COUNT($28)
  58         bnez    t0, restore_all
  59 need_resched:
  60         LONG_L  t0, TI_FLAGS($28)
  61         andi    t1, t0, _TIF_NEED_RESCHED
  62         beqz    t1, restore_all
  63         LONG_L  t0, PT_STATUS(sp)               # Interrupts off?
  64         andi    t0, 1
  65         beqz    t0, restore_all
  66         jal     preempt_schedule_irq
  67         b       need_resched
  68 #endif
  69
  70 FEXPORT(ret_from_kernel_thread)
  71         jal     schedule_tail           # a0 = struct task_struct *prev
  72         move    a0, s1
  73         jal     s0
  74         j       syscall_exit
  75
  76 FEXPORT(ret_from_fork)
  77         jal     schedule_tail           # a0 = struct task_struct *prev
  78
  79 FEXPORT(syscall_exit)
  80         local_irq_disable               # make sure need_resched and
  81                                         # signals dont change between
  82                                         # sampling and return
  83         LONG_L  a2, TI_FLAGS($28)       # current->work
  84         li      t0, _TIF_ALLWORK_MASK
  85         and     t0, a2, t0
  86         bnez    t0, syscall_exit_work
  87
  88 restore_all:                            # restore full frame
  89         .set    noat
  90         RESTORE_TEMP
  91         RESTORE_AT
  92         RESTORE_STATIC
  93 restore_partial:                # restore partial frame
  94 #ifdef CONFIG_TRACE_IRQFLAGS
  95         SAVE_STATIC
  96         SAVE_AT
  97         SAVE_TEMP
  98         LONG_L  v0, PT_STATUS(sp)
  99 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 100         and     v0, ST0_IEP
 101 #else
 102         and     v0, ST0_IE
 103 #endif
 104         beqz    v0, 1f
 105         jal     trace_hardirqs_on
 106         b       2f
 107 1:      jal     trace_hardirqs_off
 108 2:
 109         RESTORE_TEMP
 110         RESTORE_AT
 111         RESTORE_STATIC
 112 #endif
 113         RESTORE_SOME
 114         RESTORE_SP_AND_RET
 115         .set    at
 116
 117 work_pending:
 118         andi    t0, a2, _TIF_NEED_RESCHED # a2 is preloaded with TI_FLAGS
 119         beqz    t0, work_notifysig
 120 work_resched:
 121         jal     schedule
 122
 123         local_irq_disable               # make sure need_resched and
 124                                         # signals dont change between
 125                                         # sampling and return
 126         LONG_L  a2, TI_FLAGS($28)
 127         andi    t0, a2, _TIF_WORK_MASK  # is there any work to be done
 128                                         # other than syscall tracing?
 129         beqz    t0, restore_all
 130         andi    t0, a2, _TIF_NEED_RESCHED
 131         bnez    t0, work_resched
 132
 133 work_notifysig:                         # deal with pending signals and
 134                                         # notify-resume requests
 135         move    a0, sp
 136         li      a1, 0
 137         jal     do_notify_resume        # a2 already loaded
 138         j       resume_userspace_check
 139
 140 FEXPORT(syscall_exit_partial)
 141         local_irq_disable               # make sure need_resched doesn't
 142                                         # change between and return
 143         LONG_L  a2, TI_FLAGS($28)       # current->work
 144         li      t0, _TIF_ALLWORK_MASK
 145         and     t0, a2
 146         beqz    t0, restore_partial
 147         SAVE_STATIC
 148 syscall_exit_work:
 149         LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
 150         andi    t0, t0, KU_USER
 151         beqz    t0, resume_kernel
 152         li      t0, _TIF_WORK_SYSCALL_EXIT
 153         and     t0, a2                  # a2 is preloaded with TI_FLAGS
 154         beqz    t0, work_pending        # trace bit set?
 155         local_irq_enable                # could let syscall_trace_leave()
 156                                         # call schedule() instead
 157         move    a0, sp
 158         jal     syscall_trace_leave
 159         b       resume_userspace
 160
 161 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_MIPS_MT)
 162
 163 /*
 164  * MIPS32R2 Instruction Hazard Barrier - must be called
 165  *
 166  * For C code use the inline version named instruction_hazard().
 167  */
 168 LEAF(mips_ihb)
 169         .set    mips32r2
 170         jr.hb   ra
 171         nop
 172         END(mips_ihb)
 173
 174 #endif /* CONFIG_CPU_MIPSR2 or CONFIG_MIPS_MT */