MIPS: sort MIPS and MIPS_GENERIC Kconfig selects alphabetically (again)
[linux-2.6-microblaze.git] / 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 #include <asm/fpu.h>
20
21 struct task_struct;
22
23 /**
24  * resume - resume execution of a task
25  * @prev:       The task previously executed.
26  * @next:       The task to begin executing.
27  * @next_ti:    task_thread_info(next).
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
35 extern unsigned int ll_bit;
36 extern struct task_struct *ll_task;
37
38 #ifdef CONFIG_MIPS_MT_FPAFF
39
40 /*
41  * Handle the scheduler resume end of FPU affinity management.  We do this
42  * inline to try to keep the overhead down. If we have been forced to run on
43  * a "CPU" with an FPU because of a previous high level of FP computation,
44  * but did not actually use the FPU during the most recent time-slice (CU1
45  * isn't set), we undo the restriction on cpus_mask.
46  *
47  * We're not calling set_cpus_allowed() here, because we have no need to
48  * force prompt migration - we're already switching the current CPU to a
49  * different thread.
50  */
51
52 #define __mips_mt_fpaff_switch_to(prev)                                 \
53 do {                                                                    \
54         struct thread_info *__prev_ti = task_thread_info(prev);         \
55                                                                         \
56         if (cpu_has_fpu &&                                              \
57             test_ti_thread_flag(__prev_ti, TIF_FPUBOUND) &&             \
58             (!(KSTK_STATUS(prev) & ST0_CU1))) {                         \
59                 clear_ti_thread_flag(__prev_ti, TIF_FPUBOUND);          \
60                 prev->cpus_mask = prev->thread.user_cpus_allowed;       \
61         }                                                               \
62         next->thread.emulated_fp = 0;                                   \
63 } while(0)
64
65 #else
66 #define __mips_mt_fpaff_switch_to(prev) do { (void) (prev); } while (0)
67 #endif
68
69 /*
70  * Clear LLBit during context switches on MIPSr6 such that eretnc can be used
71  * unconditionally when returning to userland in entry.S.
72  */
73 #define __clear_r6_hw_ll_bit() do {                                     \
74         if (cpu_has_mips_r6)                                            \
75                 write_c0_lladdr(0);                                     \
76 } while (0)
77
78 #define __clear_software_ll_bit() do {                                  \
79         if (!__builtin_constant_p(cpu_has_llsc) || !cpu_has_llsc)       \
80                 ll_bit = 0;                                             \
81 } while (0)
82
83 /*
84  * Check FCSR for any unmasked exceptions pending set with `ptrace',
85  * clear them and send a signal.
86  */
87 #ifdef CONFIG_MIPS_FP_SUPPORT
88 # define __sanitize_fcr31(next)                                         \
89 do {                                                                    \
90         unsigned long fcr31 = mask_fcr31_x(next->thread.fpu.fcr31);     \
91         void __user *pc;                                                \
92                                                                         \
93         if (unlikely(fcr31)) {                                          \
94                 pc = (void __user *)task_pt_regs(next)->cp0_epc;        \
95                 next->thread.fpu.fcr31 &= ~fcr31;                       \
96                 force_fcr31_sig(fcr31, pc, next);                       \
97         }                                                               \
98 } while (0)
99 #else
100 # define __sanitize_fcr31(next)
101 #endif
102
103 /*
104  * For newly created kernel threads switch_to() will return to
105  * ret_from_kernel_thread, newly created user threads to ret_from_fork.
106  * That is, everything following resume() will be skipped for new threads.
107  * So everything that matters to new threads should be placed before resume().
108  */
109 #define switch_to(prev, next, last)                                     \
110 do {                                                                    \
111         __mips_mt_fpaff_switch_to(prev);                                \
112         lose_fpu_inatomic(1, prev);                                     \
113         if (tsk_used_math(next))                                        \
114                 __sanitize_fcr31(next);                                 \
115         if (cpu_has_dsp) {                                              \
116                 __save_dsp(prev);                                       \
117                 __restore_dsp(next);                                    \
118         }                                                               \
119         if (cop2_present) {                                             \
120                 set_c0_status(ST0_CU2);                                 \
121                 if ((KSTK_STATUS(prev) & ST0_CU2)) {                    \
122                         if (cop2_lazy_restore)                          \
123                                 KSTK_STATUS(prev) &= ~ST0_CU2;          \
124                         cop2_save(prev);                                \
125                 }                                                       \
126                 if (KSTK_STATUS(next) & ST0_CU2 &&                      \
127                     !cop2_lazy_restore) {                               \
128                         cop2_restore(next);                             \
129                 }                                                       \
130                 clear_c0_status(ST0_CU2);                               \
131         }                                                               \
132         __clear_r6_hw_ll_bit();                                         \
133         __clear_software_ll_bit();                                      \
134         if (cpu_has_userlocal)                                          \
135                 write_c0_userlocal(task_thread_info(next)->tp_value);   \
136         __restore_watch(next);                                          \
137         (last) = resume(prev, next, task_thread_info(next));            \
138 } while (0)
139
140 #endif /* _ASM_SWITCH_TO_H */