arch/tile/include/asm/switch_to.h

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #ifndef _ASM_TILE_SWITCH_TO_H
  16 #define _ASM_TILE_SWITCH_TO_H
  17
  18 #include <arch/sim_def.h>
  19
  20 /*
  21  * switch_to(n) should switch tasks to task nr n, first
  22  * checking that n isn't the current task, in which case it does nothing.
  23  * The number of callee-saved registers saved on the kernel stack
  24  * is defined here for use in copy_thread() and must agree with __switch_to().
  25  */
  26 #define CALLEE_SAVED_FIRST_REG 30
  27 #define CALLEE_SAVED_REGS_COUNT 24   /* r30 to r52, plus an empty to align */
  28
  29 #ifndef __ASSEMBLY__
  30
  31 struct task_struct;
  32
  33 /*
  34  * Pause the DMA engine and static network before task switching.
  35  */
  36 #define prepare_arch_switch(next) _prepare_arch_switch(next)
  37 void _prepare_arch_switch(struct task_struct *next);
  38
  39 struct task_struct;
  40 #define switch_to(prev, next, last) ((last) = _switch_to((prev), (next)))
  41 extern struct task_struct *_switch_to(struct task_struct *prev,
  42                                       struct task_struct *next);
  43
  44 /* Helper function for _switch_to(). */
  45 extern struct task_struct *__switch_to(struct task_struct *prev,
  46                                        struct task_struct *next,
  47                                        unsigned long new_system_save_k_0);
  48
  49 /* Address that switched-away from tasks are at. */
  50 extern unsigned long get_switch_to_pc(void);
  51
  52 /*
  53  * Kernel threads can check to see if they need to migrate their
  54  * stack whenever they return from a context switch; for user
  55  * threads, we defer until they are returning to user-space.
  56  */
  57 #define finish_arch_switch(prev) do {                                     \
  58         if (unlikely((prev)->state == TASK_DEAD))                         \
  59                 __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |       \
  60                         ((prev)->pid << _SIM_CONTROL_OPERATOR_BITS));     \
  61         __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
  62                 (current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
  63         if (current->mm == NULL && !kstack_hash &&                        \
  64             current_thread_info()->homecache_cpu != smp_processor_id())   \
  65                 homecache_migrate_kthread();                              \
  66 } while (0)
  67
  68 /* Support function for forking a new task. */
  69 void ret_from_fork(void);
  70
  71 /* Called from ret_from_fork() when a new process starts up. */
  72 struct task_struct *sim_notify_fork(struct task_struct *prev);
  73
  74 #endif /* !__ASSEMBLY__ */
  75
  76 #endif /* _ASM_TILE_SWITCH_TO_H */