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
21void __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
43extern unsigned int cpu_last_asid;
44
45void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
46void __new_context(struct mm_struct *mm);
47
48static 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
61static 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 */
82static inline void
83enter_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 */
93static inline void
94switch_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