arch/mn10300/include/asm/switch_to.h

   1 /* MN10300 task switching definitions
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #ifndef _ASM_SWITCH_TO_H
  12 #define _ASM_SWITCH_TO_H
  13
  14 #include <asm/barrier.h>
  15
  16 struct task_struct;
  17 struct thread_struct;
  18
  19 #if !defined(CONFIG_LAZY_SAVE_FPU)
  20 struct fpu_state_struct;
  21 extern asmlinkage void fpu_save(struct fpu_state_struct *);
  22 #define switch_fpu(prev, next)                                          \
  23         do {                                                            \
  24                 if ((prev)->thread.fpu_flags & THREAD_HAS_FPU) {        \
  25                         (prev)->thread.fpu_flags &= ~THREAD_HAS_FPU;    \
  26                         (prev)->thread.uregs->epsw &= ~EPSW_FE;         \
  27                         fpu_save(&(prev)->thread.fpu_state);            \
  28                 }                                                       \
  29         } while (0)
  30 #else
  31 #define switch_fpu(prev, next) do {} while (0)
  32 #endif
  33
  34 /* context switching is now performed out-of-line in switch_to.S */
  35 extern asmlinkage
  36 struct task_struct *__switch_to(struct thread_struct *prev,
  37                                 struct thread_struct *next,
  38                                 struct task_struct *prev_task);
  39
  40 #define switch_to(prev, next, last)                                     \
  41 do {                                                                    \
  42         switch_fpu(prev, next);                                         \
  43         current->thread.wchan = (u_long) __builtin_return_address(0);   \
  44         (last) = __switch_to(&(prev)->thread, &(next)->thread, (prev)); \
  45         mb();                                                           \
  46         current->thread.wchan = 0;                                      \
  47 } while (0)
  48
  49 #endif /* _ASM_SWITCH_TO_H */