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switch_to.h
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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, [email protected] and Carsten Langgaard, [email protected]
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 
19 struct task_struct;
20 
21 /*
22  * switch_to(n) should switch tasks to task nr n, first
23  * checking that n isn't the current task, in which case it does nothing.
24  */
25 extern asmlinkage void *resume(void *last, void *next, void *next_ti, u32 __usedfpu);
26 
27 extern unsigned int ll_bit;
28 extern struct task_struct *ll_task;
29 
30 #ifdef CONFIG_MIPS_MT_FPAFF
31 
32 /*
33  * Handle the scheduler resume end of FPU affinity management. We do this
34  * inline to try to keep the overhead down. If we have been forced to run on
35  * a "CPU" with an FPU because of a previous high level of FP computation,
36  * but did not actually use the FPU during the most recent time-slice (CU1
37  * isn't set), we undo the restriction on cpus_allowed.
38  *
39  * We're not calling set_cpus_allowed() here, because we have no need to
40  * force prompt migration - we're already switching the current CPU to a
41  * different thread.
42  */
43 
44 #define __mips_mt_fpaff_switch_to(prev) \
45 do { \
46  struct thread_info *__prev_ti = task_thread_info(prev); \
47  \
48  if (cpu_has_fpu && \
49  test_ti_thread_flag(__prev_ti, TIF_FPUBOUND) && \
50  (!(KSTK_STATUS(prev) & ST0_CU1))) { \
51  clear_ti_thread_flag(__prev_ti, TIF_FPUBOUND); \
52  prev->cpus_allowed = prev->thread.user_cpus_allowed; \
53  } \
54  next->thread.emulated_fp = 0; \
55 } while(0)
56 
57 #else
58 #define __mips_mt_fpaff_switch_to(prev) do { (void) (prev); } while (0)
59 #endif
60 
61 #define __clear_software_ll_bit() \
62 do { \
63  if (!__builtin_constant_p(cpu_has_llsc) || !cpu_has_llsc) \
64  ll_bit = 0; \
65 } while (0)
66 
67 #define switch_to(prev, next, last) \
68 do { \
69  u32 __usedfpu; \
70  __mips_mt_fpaff_switch_to(prev); \
71  if (cpu_has_dsp) \
72  __save_dsp(prev); \
73  __clear_software_ll_bit(); \
74  __usedfpu = test_and_clear_tsk_thread_flag(prev, TIF_USEDFPU); \
75  (last) = resume(prev, next, task_thread_info(next), __usedfpu); \
76 } while (0)
77 
78 #define finish_arch_switch(prev) \
79 do { \
80  if (cpu_has_dsp) \
81  __restore_dsp(current); \
82  if (cpu_has_userlocal) \
83  write_c0_userlocal(current_thread_info()->tp_value); \
84  __restore_watch(); \
85 } while (0)
86 
87 #endif /* _ASM_SWITCH_TO_H */