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  * switch_to(n) should switch tasks to task nr n, first
  24  * checking that n isn't the current task, in which case it does nothing.
  25  */
  26 extern asmlinkage void *resume(void *last, void *next, void *next_ti, u32 __usedfpu);
  27
  28 extern unsigned int ll_bit;
  29 extern struct task_struct *ll_task;
  30
  31 #ifdef CONFIG_MIPS_MT_FPAFF
  32
  33 /*
  34  * Handle the scheduler resume end of FPU affinity management.  We do this
  35  * inline to try to keep the overhead down. If we have been forced to run on
  36  * a "CPU" with an FPU because of a previous high level of FP computation,
  37  * but did not actually use the FPU during the most recent time-slice (CU1
  38  * isn't set), we undo the restriction on cpus_allowed.
  39  *
  40  * We're not calling set_cpus_allowed() here, because we have no need to
  41  * force prompt migration - we're already switching the current CPU to a
  42  * different thread.
  43  */
  44
  45 #define __mips_mt_fpaff_switch_to(prev)                                 \
  46 do {                                                                    \
  47         struct thread_info *__prev_ti = task_thread_info(prev);         \
  48                                                                         \
  49         if (cpu_has_fpu &&                                              \
  50             test_ti_thread_flag(__prev_ti, TIF_FPUBOUND) &&             \
  51             (!(KSTK_STATUS(prev) & ST0_CU1))) {                         \
  52                 clear_ti_thread_flag(__prev_ti, TIF_FPUBOUND);          \
  53                 prev->cpus_allowed = prev->thread.user_cpus_allowed;    \
  54         }                                                               \
  55         next->thread.emulated_fp = 0;                                   \
  56 } while(0)
  57
  58 #else
  59 #define __mips_mt_fpaff_switch_to(prev) do { (void) (prev); } while (0)
  60 #endif
  61
  62 #define __clear_software_ll_bit()                                       \
  63 do {                                                                    \
  64         if (!__builtin_constant_p(cpu_has_llsc) || !cpu_has_llsc)       \
  65                 ll_bit = 0;                                             \
  66 } while (0)
  67
  68 #define switch_to(prev, next, last)                                     \
  69 do {                                                                    \
  70         u32 __usedfpu, __c0_stat;                                       \
  71         __mips_mt_fpaff_switch_to(prev);                                \
  72         if (cpu_has_dsp)                                                \
  73                 __save_dsp(prev);                                       \
  74         if (cop2_present && (KSTK_STATUS(prev) & ST0_CU2)) {            \
  75                 if (cop2_lazy_restore)                                  \
  76                         KSTK_STATUS(prev) &= ~ST0_CU2;                  \
  77                 __c0_stat = read_c0_status();                           \
  78                 write_c0_status(__c0_stat | ST0_CU2);                   \
  79                 cop2_save(&prev->thread.cp2);                           \
  80                 write_c0_status(__c0_stat & ~ST0_CU2);                  \
  81         }                                                               \
  82         __clear_software_ll_bit();                                      \
  83         __usedfpu = test_and_clear_tsk_thread_flag(prev, TIF_USEDFPU);  \
  84         (last) = resume(prev, next, task_thread_info(next), __usedfpu); \
  85 } while (0)
  86
  87 #define finish_arch_switch(prev)                                        \
  88 do {                                                                    \
  89         u32 __c0_stat;                                                  \
  90         if (cop2_present && !cop2_lazy_restore &&                       \
  91                         (KSTK_STATUS(current) & ST0_CU2)) {             \
  92                 __c0_stat = read_c0_status();                           \
  93                 write_c0_status(__c0_stat | ST0_CU2);                   \
  94                 cop2_restore(&current->thread.cp2);                     \
  95                 write_c0_status(__c0_stat & ~ST0_CU2);                  \
  96         }                                                               \
  97         if (cpu_has_dsp)                                                \
  98                 __restore_dsp(current);                                 \
  99         if (cpu_has_userlocal)                                          \
 100                 write_c0_userlocal(current_thread_info()->tp_value);    \
 101         __restore_watch();                                              \
 102 } while (0)
 103
 104 #endif /* _ASM_SWITCH_TO_H */