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Diffstat (limited to 'arch/ia64/include/asm/switch_to.h')
-rw-r--r-- | arch/ia64/include/asm/switch_to.h | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/arch/ia64/include/asm/switch_to.h b/arch/ia64/include/asm/switch_to.h new file mode 100644 index 000000000000..cb2412fcd17f --- /dev/null +++ b/arch/ia64/include/asm/switch_to.h | |||
@@ -0,0 +1,87 @@ | |||
1 | /* | ||
2 | * Low-level task switching. This is based on information published in | ||
3 | * the Processor Abstraction Layer and the System Abstraction Layer | ||
4 | * manual. | ||
5 | * | ||
6 | * Copyright (C) 1998-2003 Hewlett-Packard Co | ||
7 | * David Mosberger-Tang <davidm@hpl.hp.com> | ||
8 | * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com> | ||
9 | * Copyright (C) 1999 Don Dugger <don.dugger@intel.com> | ||
10 | */ | ||
11 | #ifndef _ASM_IA64_SWITCH_TO_H | ||
12 | #define _ASM_IA64_SWITCH_TO_H | ||
13 | |||
14 | #include <linux/percpu.h> | ||
15 | |||
16 | struct task_struct; | ||
17 | |||
18 | /* | ||
19 | * Context switch from one thread to another. If the two threads have | ||
20 | * different address spaces, schedule() has already taken care of | ||
21 | * switching to the new address space by calling switch_mm(). | ||
22 | * | ||
23 | * Disabling access to the fph partition and the debug-register | ||
24 | * context switch MUST be done before calling ia64_switch_to() since a | ||
25 | * newly created thread returns directly to | ||
26 | * ia64_ret_from_syscall_clear_r8. | ||
27 | */ | ||
28 | extern struct task_struct *ia64_switch_to (void *next_task); | ||
29 | |||
30 | extern void ia64_save_extra (struct task_struct *task); | ||
31 | extern void ia64_load_extra (struct task_struct *task); | ||
32 | |||
33 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING | ||
34 | extern void ia64_account_on_switch (struct task_struct *prev, struct task_struct *next); | ||
35 | # define IA64_ACCOUNT_ON_SWITCH(p,n) ia64_account_on_switch(p,n) | ||
36 | #else | ||
37 | # define IA64_ACCOUNT_ON_SWITCH(p,n) | ||
38 | #endif | ||
39 | |||
40 | #ifdef CONFIG_PERFMON | ||
41 | DECLARE_PER_CPU(unsigned long, pfm_syst_info); | ||
42 | # define PERFMON_IS_SYSWIDE() (__get_cpu_var(pfm_syst_info) & 0x1) | ||
43 | #else | ||
44 | # define PERFMON_IS_SYSWIDE() (0) | ||
45 | #endif | ||
46 | |||
47 | #define IA64_HAS_EXTRA_STATE(t) \ | ||
48 | ((t)->thread.flags & (IA64_THREAD_DBG_VALID|IA64_THREAD_PM_VALID) \ | ||
49 | || PERFMON_IS_SYSWIDE()) | ||
50 | |||
51 | #define __switch_to(prev,next,last) do { \ | ||
52 | IA64_ACCOUNT_ON_SWITCH(prev, next); \ | ||
53 | if (IA64_HAS_EXTRA_STATE(prev)) \ | ||
54 | ia64_save_extra(prev); \ | ||
55 | if (IA64_HAS_EXTRA_STATE(next)) \ | ||
56 | ia64_load_extra(next); \ | ||
57 | ia64_psr(task_pt_regs(next))->dfh = !ia64_is_local_fpu_owner(next); \ | ||
58 | (last) = ia64_switch_to((next)); \ | ||
59 | } while (0) | ||
60 | |||
61 | #ifdef CONFIG_SMP | ||
62 | /* | ||
63 | * In the SMP case, we save the fph state when context-switching away from a thread that | ||
64 | * modified fph. This way, when the thread gets scheduled on another CPU, the CPU can | ||
65 | * pick up the state from task->thread.fph, avoiding the complication of having to fetch | ||
66 | * the latest fph state from another CPU. In other words: eager save, lazy restore. | ||
67 | */ | ||
68 | # define switch_to(prev,next,last) do { \ | ||
69 | if (ia64_psr(task_pt_regs(prev))->mfh && ia64_is_local_fpu_owner(prev)) { \ | ||
70 | ia64_psr(task_pt_regs(prev))->mfh = 0; \ | ||
71 | (prev)->thread.flags |= IA64_THREAD_FPH_VALID; \ | ||
72 | __ia64_save_fpu((prev)->thread.fph); \ | ||
73 | } \ | ||
74 | __switch_to(prev, next, last); \ | ||
75 | /* "next" in old context is "current" in new context */ \ | ||
76 | if (unlikely((current->thread.flags & IA64_THREAD_MIGRATION) && \ | ||
77 | (task_cpu(current) != \ | ||
78 | task_thread_info(current)->last_cpu))) { \ | ||
79 | platform_migrate(current); \ | ||
80 | task_thread_info(current)->last_cpu = task_cpu(current); \ | ||
81 | } \ | ||
82 | } while (0) | ||
83 | #else | ||
84 | # define switch_to(prev,next,last) __switch_to(prev, next, last) | ||
85 | #endif | ||
86 | |||
87 | #endif /* _ASM_IA64_SWITCH_TO_H */ | ||