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 #ifdef CONFIG_MIPS_MT_SMTC
  20 #include <asm/mipsmtregs.h>
  21 #endif
  22
  23 #ifndef CONFIG_PREEMPT
  24 #define resume_kernel   restore_all
  25 #else
  26 #define __ret_from_irq  ret_from_exception
  27 #endif
  28
  29         .text
  30         .align  5
  31 #ifndef CONFIG_PREEMPT
  32 FEXPORT(ret_from_exception)
  33         local_irq_disable                       # preempt stop
  34         b       __ret_from_irq
  35 #endif
  36 FEXPORT(ret_from_irq)
  37         LONG_S  s0, TI_REGS($28)
  38 FEXPORT(__ret_from_irq)
  39 /*
  40  * We can be coming here from a syscall done in the kernel space,
  41  * e.g. a failed kernel_execve().
  42  */
  43 resume_userspace_check:
  44         LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
  45         andi    t0, t0, KU_USER
  46         beqz    t0, resume_kernel
  47
  48 resume_userspace:
  49         local_irq_disable               # make sure we dont miss an
  50                                         # interrupt setting need_resched
  51                                         # between sampling and return
  52         LONG_L  a2, TI_FLAGS($28)       # current->work
  53         andi    t0, a2, _TIF_WORK_MASK  # (ignoring syscall_trace)
  54         bnez    t0, work_pending
  55         j       restore_all
  56
  57 #ifdef CONFIG_PREEMPT
  58 resume_kernel:
  59         local_irq_disable
  60         lw      t0, TI_PRE_COUNT($28)
  61         bnez    t0, restore_all
  62 need_resched:
  63         LONG_L  t0, TI_FLAGS($28)
  64         andi    t1, t0, _TIF_NEED_RESCHED
  65         beqz    t1, restore_all
  66         LONG_L  t0, PT_STATUS(sp)               # Interrupts off?
  67         andi    t0, 1
  68         beqz    t0, restore_all
  69         jal     preempt_schedule_irq
  70         b       need_resched
  71 #endif
  72
  73 FEXPORT(ret_from_kernel_thread)
  74         jal     schedule_tail           # a0 = struct task_struct *prev
  75         move    a0, s1
  76         jal     s0
  77         j       syscall_exit
  78
  79 FEXPORT(ret_from_fork)
  80         jal     schedule_tail           # a0 = struct task_struct *prev
  81
  82 FEXPORT(syscall_exit)
  83         local_irq_disable               # make sure need_resched and
  84                                         # signals dont change between
  85                                         # sampling and return
  86         LONG_L  a2, TI_FLAGS($28)       # current->work
  87         li      t0, _TIF_ALLWORK_MASK
  88         and     t0, a2, t0
  89         bnez    t0, syscall_exit_work
  90
  91 restore_all:                            # restore full frame
  92 #ifdef CONFIG_MIPS_MT_SMTC
  93 #ifdef CONFIG_MIPS_MT_SMTC_IM_BACKSTOP
  94 /* Re-arm any temporarily masked interrupts not explicitly "acked" */
  95         mfc0    v0, CP0_TCSTATUS
  96         ori     v1, v0, TCSTATUS_IXMT
  97         mtc0    v1, CP0_TCSTATUS
  98         andi    v0, TCSTATUS_IXMT
  99         _ehb
 100         mfc0    t0, CP0_TCCONTEXT
 101         DMT     9                               # dmt t1
 102         jal     mips_ihb
 103         mfc0    t2, CP0_STATUS
 104         andi    t3, t0, 0xff00
 105         or      t2, t2, t3
 106         mtc0    t2, CP0_STATUS
 107         _ehb
 108         andi    t1, t1, VPECONTROL_TE
 109         beqz    t1, 1f
 110         EMT
 111 1:
 112         mfc0    v1, CP0_TCSTATUS
 113         /* We set IXMT above, XOR should clear it here */
 114         xori    v1, v1, TCSTATUS_IXMT
 115         or      v1, v0, v1
 116         mtc0    v1, CP0_TCSTATUS
 117         _ehb
 118         xor     t0, t0, t3
 119         mtc0    t0, CP0_TCCONTEXT
 120 #endif /* CONFIG_MIPS_MT_SMTC_IM_BACKSTOP */
 121 /* Detect and execute deferred IPI "interrupts" */
 122         LONG_L  s0, TI_REGS($28)
 123         LONG_S  sp, TI_REGS($28)
 124         jal     deferred_smtc_ipi
 125         LONG_S  s0, TI_REGS($28)
 126 #endif /* CONFIG_MIPS_MT_SMTC */
 127         .set    noat
 128         RESTORE_TEMP
 129         RESTORE_AT
 130         RESTORE_STATIC
 131 restore_partial:                # restore partial frame
 132 #ifdef CONFIG_TRACE_IRQFLAGS
 133         SAVE_STATIC
 134         SAVE_AT
 135         SAVE_TEMP
 136         LONG_L  v0, PT_STATUS(sp)
 137 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 138         and     v0, ST0_IEP
 139 #else
 140         and     v0, ST0_IE
 141 #endif
 142         beqz    v0, 1f
 143         jal     trace_hardirqs_on
 144         b       2f
 145 1:      jal     trace_hardirqs_off
 146 2:
 147         RESTORE_TEMP
 148         RESTORE_AT
 149         RESTORE_STATIC
 150 #endif
 151         RESTORE_SOME
 152         RESTORE_SP_AND_RET
 153         .set    at
 154
 155 work_pending:
 156         andi    t0, a2, _TIF_NEED_RESCHED # a2 is preloaded with TI_FLAGS
 157         beqz    t0, work_notifysig
 158 work_resched:
 159         jal     schedule
 160
 161         local_irq_disable               # make sure need_resched and
 162                                         # signals dont change between
 163                                         # sampling and return
 164         LONG_L  a2, TI_FLAGS($28)
 165         andi    t0, a2, _TIF_WORK_MASK  # is there any work to be done
 166                                         # other than syscall tracing?
 167         beqz    t0, restore_all
 168         andi    t0, a2, _TIF_NEED_RESCHED
 169         bnez    t0, work_resched
 170
 171 work_notifysig:                         # deal with pending signals and
 172                                         # notify-resume requests
 173         move    a0, sp
 174         li      a1, 0
 175         jal     do_notify_resume        # a2 already loaded
 176         j       resume_userspace_check
 177
 178 FEXPORT(syscall_exit_partial)
 179         local_irq_disable               # make sure need_resched doesn't
 180                                         # change between and return
 181         LONG_L  a2, TI_FLAGS($28)       # current->work
 182         li      t0, _TIF_ALLWORK_MASK
 183         and     t0, a2
 184         beqz    t0, restore_partial
 185         SAVE_STATIC
 186 syscall_exit_work:
 187         LONG_L  t0, PT_STATUS(sp)               # returning to kernel mode?
 188         andi    t0, t0, KU_USER
 189         beqz    t0, resume_kernel
 190         li      t0, _TIF_WORK_SYSCALL_EXIT
 191         and     t0, a2                  # a2 is preloaded with TI_FLAGS
 192         beqz    t0, work_pending        # trace bit set?
 193         local_irq_enable                # could let syscall_trace_leave()
 194                                         # call schedule() instead
 195         move    a0, sp
 196         jal     syscall_trace_leave
 197         b       resume_userspace
 198
 199 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_MIPS_MT)
 200
 201 /*
 202  * MIPS32R2 Instruction Hazard Barrier - must be called
 203  *
 204  * For C code use the inline version named instruction_hazard().
 205  */
 206 LEAF(mips_ihb)
 207         .set    mips32r2
 208         jr.hb   ra
 209         nop
 210         END(mips_ihb)
 211
 212 #endif /* CONFIG_CPU_MIPSR2 or CONFIG_MIPS_MT */