arch/mn10300/kernel/switch_to.S

   1 ###############################################################################
   2 #
   3 # MN10300 Context switch operation
   4 #
   5 # Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   6 # Written by David Howells (dhowells@redhat.com)
   7 #
   8 # This program is free software; you can redistribute it and/or
   9 # modify it under the terms of the GNU General Public Licence
  10 # as published by the Free Software Foundation; either version
  11 # 2 of the Licence, or (at your option) any later version.
  12 #
  13 ###############################################################################
  14 #include <linux/sys.h>
  15 #include <linux/linkage.h>
  16 #include <asm/thread_info.h>
  17 #include <asm/cpu-regs.h>
  18 #ifdef CONFIG_SMP
  19 #include <proc/smp-regs.h>
  20 #endif /* CONFIG_SMP */
  21
  22         .text
  23
  24 ###############################################################################
  25 #
  26 # struct task_struct *__switch_to(struct thread_struct *prev,
  27 #                                 struct thread_struct *next,
  28 #                                 struct task_struct *prev_task)
  29 #
  30 ###############################################################################
  31 ENTRY(__switch_to)
  32         movm    [d2,d3,a2,a3,exreg1],(sp)
  33         or      EPSW_NMID,epsw
  34
  35         mov     (44,sp),d2
  36
  37         mov     d0,a0
  38         mov     d1,a1
  39
  40         # save prev context
  41         mov     __switch_back,d0
  42         mov     d0,(THREAD_PC,a0)
  43         mov     sp,a2
  44         mov     a2,(THREAD_SP,a0)
  45         mov     a3,(THREAD_A3,a0)
  46
  47         mov     (THREAD_A3,a1),a3
  48         mov     (THREAD_SP,a1),a2
  49
  50         # switch
  51         mov     a2,sp
  52
  53         # load next context
  54         GET_THREAD_INFO a2
  55         mov     a2,(__current_ti)
  56         mov     (TI_task,a2),a2
  57         mov     a2,(__current)
  58 #ifdef CONFIG_MN10300_CURRENT_IN_E2
  59         mov     a2,e2
  60 #endif
  61
  62         mov     (THREAD_PC,a1),a2
  63         mov     d2,d0                   # for ret_from_fork
  64         mov     d0,a0                   # for __switch_to
  65
  66         jmp     (a2)
  67
  68 __switch_back:
  69         and     ~EPSW_NMID,epsw
  70         ret     [d2,d3,a2,a3,exreg1],32