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/compiler.h>
  14 #include <asm/regdef.h>
  15 #include <asm/mipsregs.h>
  16 #include <asm/stackframe.h>
  17 #include <asm/isadep.h>
  18 #include <asm/thread_info.h>
  19 #include <asm/war.h>
  20
  21 #ifndef CONFIG_PREEMPT
  22 #define resume_kernel   restore_all
  23 #else
  24 #define __ret_from_irq  ret_from_exception
  25 #endif
  26
  27         .text
  28         .align  5
  29 #ifndef CONFIG_PREEMPT
  30 FEXPORT(ret_from_exception)
  31         local_irq_disable                       # preempt stop
  32         b       __ret_from_irq
  33 #endif
  34 FEXPORT(ret_from_irq)
  35         LONG_S  s0, TI_REGS($28)
  36 FEXPORT(__ret_from_irq)
  37 /*
  38  * We can be coming here from a syscall done in the kernel space,
  39  * e.g. a failed kernel_execve().
  40  */
  41 resume_userspace_check:
  42         LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
  43         andi    t0, t0, KU_USER
  44         beqz    t0, resume_kernel
  45
  46 resume_userspace:
  47         local_irq_disable               # make sure we dont miss an
  48                                         # interrupt setting need_resched
  49                                         # between sampling and return
  50 #ifdef CONFIG_MIPSR2_TO_R6_EMULATOR
  51         lw      k0, TI_R2_EMUL_RET($28)
  52         bnez    k0, restore_all_from_r2_emul
  53 #endif
  54
  55         LONG_L  a2, TI_FLAGS($28)       # current->work
  56         andi    t0, a2, _TIF_WORK_MASK  # (ignoring syscall_trace)
  57         bnez    t0, work_pending
  58         j       restore_all
  59
  60 #ifdef CONFIG_PREEMPT
  61 resume_kernel:
  62         local_irq_disable
  63         lw      t0, TI_PRE_COUNT($28)
  64         bnez    t0, restore_all
  65 need_resched:
  66         LONG_L  t0, TI_FLAGS($28)
  67         andi    t1, t0, _TIF_NEED_RESCHED
  68         beqz    t1, restore_all
  69         LONG_L  t0, PT_STATUS(sp)               # Interrupts off?
  70         andi    t0, 1
  71         beqz    t0, restore_all
  72         jal     preempt_schedule_irq
  73         b       need_resched
  74 #endif
  75
  76 FEXPORT(ret_from_kernel_thread)
  77         jal     schedule_tail           # a0 = struct task_struct *prev
  78         move    a0, s1
  79         jal     s0
  80         j       syscall_exit
  81
  82 FEXPORT(ret_from_fork)
  83         jal     schedule_tail           # a0 = struct task_struct *prev
  84
  85 FEXPORT(syscall_exit)
  86         local_irq_disable               # make sure need_resched and
  87                                         # signals dont change between
  88                                         # sampling and return
  89         LONG_L  a2, TI_FLAGS($28)       # current->work
  90         li      t0, _TIF_ALLWORK_MASK
  91         and     t0, a2, t0
  92         bnez    t0, syscall_exit_work
  93
  94 restore_all:                            # restore full frame
  95         .set    noat
  96         RESTORE_TEMP
  97         RESTORE_AT
  98         RESTORE_STATIC
  99 restore_partial:                # restore partial frame
 100 #ifdef CONFIG_TRACE_IRQFLAGS
 101         SAVE_STATIC
 102         SAVE_AT
 103         SAVE_TEMP
 104         LONG_L  v0, PT_STATUS(sp)
 105 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 106         and     v0, ST0_IEP
 107 #else
 108         and     v0, ST0_IE
 109 #endif
 110         beqz    v0, 1f
 111         jal     trace_hardirqs_on
 112         b       2f
 113 1:      jal     trace_hardirqs_off
 114 2:
 115         RESTORE_TEMP
 116         RESTORE_AT
 117         RESTORE_STATIC
 118 #endif
 119         RESTORE_SOME
 120         RESTORE_SP_AND_RET
 121         .set    at
 122
 123 #ifdef CONFIG_MIPSR2_TO_R6_EMULATOR
 124 restore_all_from_r2_emul:                       # restore full frame
 125         .set    noat
 126         sw      zero, TI_R2_EMUL_RET($28)       # reset it
 127         RESTORE_TEMP
 128         RESTORE_AT
 129         RESTORE_STATIC
 130         RESTORE_SOME
 131         LONG_L  sp, PT_R29(sp)
 132         eretnc
 133         .set    at
 134 #endif
 135
 136 work_pending:
 137         andi    t0, a2, _TIF_NEED_RESCHED # a2 is preloaded with TI_FLAGS
 138         beqz    t0, work_notifysig
 139 work_resched:
 140         jal     schedule
 141
 142         local_irq_disable               # make sure need_resched and
 143                                         # signals dont change between
 144                                         # sampling and return
 145         LONG_L  a2, TI_FLAGS($28)
 146         andi    t0, a2, _TIF_WORK_MASK  # is there any work to be done
 147                                         # other than syscall tracing?
 148         beqz    t0, restore_all
 149         andi    t0, a2, _TIF_NEED_RESCHED
 150         bnez    t0, work_resched
 151
 152 work_notifysig:                         # deal with pending signals and
 153                                         # notify-resume requests
 154         move    a0, sp
 155         li      a1, 0
 156         jal     do_notify_resume        # a2 already loaded
 157         j       resume_userspace_check
 158
 159 FEXPORT(syscall_exit_partial)
 160         local_irq_disable               # make sure need_resched doesn't
 161                                         # change between and return
 162         LONG_L  a2, TI_FLAGS($28)       # current->work
 163         li      t0, _TIF_ALLWORK_MASK
 164         and     t0, a2
 165         beqz    t0, restore_partial
 166         SAVE_STATIC
 167 syscall_exit_work:
 168         LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
 169         andi    t0, t0, KU_USER
 170         beqz    t0, resume_kernel
 171         li      t0, _TIF_WORK_SYSCALL_EXIT
 172         and     t0, a2                  # a2 is preloaded with TI_FLAGS
 173         beqz    t0, work_pending        # trace bit set?
 174         local_irq_enable                # could let syscall_trace_leave()
 175                                         # call schedule() instead
 176         move    a0, sp
 177         jal     syscall_trace_leave
 178         b       resume_userspace
 179
 180 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) || \
 181     defined(CONFIG_MIPS_MT)
 182
 183 /*
 184  * MIPS32R2 Instruction Hazard Barrier - must be called
 185  *
 186  * For C code use the inline version named instruction_hazard().
 187  */
 188 LEAF(mips_ihb)
 189         .set    MIPS_ISA_LEVEL_RAW
 190         jr.hb   ra
 191         nop
 192         END(mips_ihb)
 193
 194 #endif /* CONFIG_CPU_MIPSR2 or CONFIG_CPU_MIPSR6 or CONFIG_MIPS_MT */