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Linux kernel mirror (for testing)
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linux
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
20void __check_kvm_seq(struct mm_struct *mm);
21
22#if __LINUX_ARM_ARCH__ >= 6
23
24/*
25 * On ARMv6, we have the following structure in the Context ID:
26 *
27 * 31 7 0
28 * +-------------------------+-----------+
29 * | process ID | ASID |
30 * +-------------------------+-----------+
31 * | context ID |
32 * +-------------------------------------+
33 *
34 * The ASID is used to tag entries in the CPU caches and TLBs.
35 * The context ID is used by debuggers and trace logic, and
36 * should be unique within all running processes.
37 */
38#define ASID_BITS 8
39#define ASID_MASK ((~0) << ASID_BITS)
40
41extern unsigned int cpu_last_asid;
42
43void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
44void __new_context(struct mm_struct *mm);
45
46static inline void check_context(struct mm_struct *mm)
47{
48 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
49 __new_context(mm);
50
51 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
52 __check_kvm_seq(mm);
53}
54
55#define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0)
56
57#else
58
59static inline void check_context(struct mm_struct *mm)
60{
61 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
62 __check_kvm_seq(mm);
63}
64
65#define init_new_context(tsk,mm) 0
66
67#endif
68
69#define destroy_context(mm) do { } while(0)
70
71/*
72 * This is called when "tsk" is about to enter lazy TLB mode.
73 *
74 * mm: describes the currently active mm context
75 * tsk: task which is entering lazy tlb
76 * cpu: cpu number which is entering lazy tlb
77 *
78 * tsk->mm will be NULL
79 */
80static inline void
81enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
82{
83}
84
85/*
86 * This is the actual mm switch as far as the scheduler
87 * is concerned. No registers are touched. We avoid
88 * calling the CPU specific function when the mm hasn't
89 * actually changed.
90 */
91static inline void
92switch_mm(struct mm_struct *prev, struct mm_struct *next,
93 struct task_struct *tsk)
94{
95#ifdef CONFIG_MMU
96 unsigned int cpu = smp_processor_id();
97
98 if (prev != next) {
99 cpu_set(cpu, next->cpu_vm_mask);
100 check_context(next);
101 cpu_switch_mm(next->pgd, next);
102 if (cache_is_vivt())
103 cpu_clear(cpu, prev->cpu_vm_mask);
104 }
105#endif
106}
107
108#define deactivate_mm(tsk,mm) do { } while (0)
109#define activate_mm(prev,next) switch_mm(prev, next, NULL)
110
111#endif