arch/mips/include/asm/switch_to.h

   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, 95, 96, 97, 98, 99, 2003, 06 by Ralf Baechle
   7  * Copyright (C) 1996 by Paul M. Antoine
   8  * Copyright (C) 1999 Silicon Graphics
   9  * Kevin D. Kissell, kevink@mips.org and Carsten Langgaard, carstenl@mips.com
  10  * Copyright (C) 2000 MIPS Technologies, Inc.
  11  */
  12 #ifndef _ASM_SWITCH_TO_H
  13 #define _ASM_SWITCH_TO_H
  14
  15 #include <asm/cpu-features.h>
  16 #include <asm/watch.h>
  17 #include <asm/dsp.h>
  18 #include <asm/cop2.h>
  19
  20 struct task_struct;
  21
  22 /**
  23  * resume - resume execution of a task
  24  * @prev:       The task previously executed.
  25  * @next:       The task to begin executing.
  26  * @next_ti:    task_thread_info(next).
  27  * @usedfpu:    Non-zero if prev's FP context should be saved.
  28  *
  29  * This function is used whilst scheduling to save the context of prev & load
  30  * the context of next. Returns prev.
  31  */
  32 extern asmlinkage struct task_struct *resume(struct task_struct *prev,
  33                 struct task_struct *next, struct thread_info *next_ti,
  34                 u32 usedfpu);
  35
  36 extern unsigned int ll_bit;
  37 extern struct task_struct *ll_task;
  38
  39 #ifdef CONFIG_MIPS_MT_FPAFF
  40
  41 /*
  42  * Handle the scheduler resume end of FPU affinity management.  We do this
  43  * inline to try to keep the overhead down. If we have been forced to run on
  44  * a "CPU" with an FPU because of a previous high level of FP computation,
  45  * but did not actually use the FPU during the most recent time-slice (CU1
  46  * isn't set), we undo the restriction on cpus_allowed.
  47  *
  48  * We're not calling set_cpus_allowed() here, because we have no need to
  49  * force prompt migration - we're already switching the current CPU to a
  50  * different thread.
  51  */
  52
  53 #define __mips_mt_fpaff_switch_to(prev)                                 \
  54 do {                                                                    \
  55         struct thread_info *__prev_ti = task_thread_info(prev);         \
  56                                                                         \
  57         if (cpu_has_fpu &&                                              \
  58             test_ti_thread_flag(__prev_ti, TIF_FPUBOUND) &&             \
  59             (!(KSTK_STATUS(prev) & ST0_CU1))) {                         \
  60                 clear_ti_thread_flag(__prev_ti, TIF_FPUBOUND);          \
  61                 prev->cpus_allowed = prev->thread.user_cpus_allowed;    \
  62         }                                                               \
  63         next->thread.emulated_fp = 0;                                   \
  64 } while(0)
  65
  66 #else
  67 #define __mips_mt_fpaff_switch_to(prev) do { (void) (prev); } while (0)
  68 #endif
  69
  70 #define __clear_software_ll_bit()                                       \
  71 do {                                                                    \
  72         if (!__builtin_constant_p(cpu_has_llsc) || !cpu_has_llsc)       \
  73                 ll_bit = 0;                                             \
  74 } while (0)
  75
  76 #define switch_to(prev, next, last)                                     \
  77 do {                                                                    \
  78         u32 __usedfpu, __c0_stat;                                       \
  79         __mips_mt_fpaff_switch_to(prev);                                \
  80         if (cpu_has_dsp)                                                \
  81                 __save_dsp(prev);                                       \
  82         if (cop2_present && (KSTK_STATUS(prev) & ST0_CU2)) {            \
  83                 if (cop2_lazy_restore)                                  \
  84                         KSTK_STATUS(prev) &= ~ST0_CU2;                  \
  85                 __c0_stat = read_c0_status();                           \
  86                 write_c0_status(__c0_stat | ST0_CU2);                   \
  87                 cop2_save(&prev->thread.cp2);                           \
  88                 write_c0_status(__c0_stat & ~ST0_CU2);                  \
  89         }                                                               \
  90         __clear_software_ll_bit();                                      \
  91         __usedfpu = test_and_clear_tsk_thread_flag(prev, TIF_USEDFPU);  \
  92         (last) = resume(prev, next, task_thread_info(next), __usedfpu); \
  93 } while (0)
  94
  95 #define finish_arch_switch(prev)                                        \
  96 do {                                                                    \
  97         u32 __c0_stat;                                                  \
  98         if (cop2_present && !cop2_lazy_restore &&                       \
  99                         (KSTK_STATUS(current) & ST0_CU2)) {             \
 100                 __c0_stat = read_c0_status();                           \
 101                 write_c0_status(__c0_stat | ST0_CU2);                   \
 102                 cop2_restore(&current->thread.cp2);                     \
 103                 write_c0_status(__c0_stat & ~ST0_CU2);                  \
 104         }                                                               \
 105         if (cpu_has_dsp)                                                \
 106                 __restore_dsp(current);                                 \
 107         if (cpu_has_userlocal)                                          \
 108                 write_c0_userlocal(current_thread_info()->tp_value);    \
 109         __restore_watch();                                              \
 110 } while (0)
 111
 112 #endif /* _ASM_SWITCH_TO_H */