1 /*
2 * linux/include/asm-arm/mmu_context.h
3 *
4 * Copyright (C) 1996 Russell King.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Changelog:
11 * 27-06-1996 RMK Created
12 */
13 #ifndef __ASM_ARM_MMU_CONTEXT_H
14 #define __ASM_ARM_MMU_CONTEXT_H
15
16 #include <linux/compiler.h>
17 #include <asm/cacheflush.h>
18 #include <asm/proc-fns.h>
19 #include <asm-generic/mm_hooks.h>
20
21 void __check_kvm_seq(struct mm_struct *mm);
22
23 #ifdef CONFIG_CPU_HAS_ASID
24
25 /*
26 * On ARMv6, we have the following structure in the Context ID:
27 *
28 * 31 7 0
29 * +-------------------------+-----------+
30 * | process ID | ASID |
31 * +-------------------------+-----------+
32 * | context ID |
33 * +-------------------------------------+
34 *
35 * The ASID is used to tag entries in the CPU caches and TLBs.
36 * The context ID is used by debuggers and trace logic, and
37 * should be unique within all running processes.
38 */
39 #define ASID_BITS 8
40 #define ASID_MASK ((~0) << ASID_BITS)
41 #define ASID_FIRST_VERSION (1 << ASID_BITS)
42
43 extern unsigned int cpu_last_asid;
44
45 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
46 void __new_context(struct mm_struct *mm);
47
48 static inline void check_context(struct mm_struct *mm)
49 {
50 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
51 __new_context(mm);
52
53 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
54 __check_kvm_seq(mm);
55 }
56
57 #define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0)
58
59 #else
60
61 static inline void check_context(struct mm_struct *mm)
62 {
63 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
64 __check_kvm_seq(mm);
65 }
66
67 #define init_new_context(tsk,mm) 0
68
69 #endif
70
71 #define destroy_context(mm) do { } while(0)
72
73 /*
74 * This is called when "tsk" is about to enter lazy TLB mode.
75 *
76 * mm: describes the currently active mm context
77 * tsk: task which is entering lazy tlb
78 * cpu: cpu number which is entering lazy tlb
79 *
80 * tsk->mm will be NULL
81 */
82 static inline void
83 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
84 {
85 }
86
87 /*
88 * This is the actual mm switch as far as the scheduler
89 * is concerned. No registers are touched. We avoid
90 * calling the CPU specific function when the mm hasn't
91 * actually changed.
92 */
93 static inline void
94 switch_mm(struct mm_struct *prev, struct mm_struct *next,
95 struct task_struct *tsk)
96 {
97 #ifdef CONFIG_MMU
98 unsigned int cpu = smp_processor_id();
99
100 if (!cpu_test_and_set(cpu, next->cpu_vm_mask) || prev != next) {
101 check_context(next);
102 cpu_switch_mm(next->pgd, next);
103 if (cache_is_vivt())
104 cpu_clear(cpu, prev->cpu_vm_mask);
105 }
106 #endif
107 }
108
109 #define deactivate_mm(tsk,mm) do { } while (0)
110 #define activate_mm(prev,next) switch_mm(prev, next, NULL)
111
112 #endif
113
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