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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Russell King8dc39b82005-11-16 17:23:57 +000016#include <linux/compiler.h>
Russell King4fe15ba2005-11-06 19:47:04 +000017#include <asm/cacheflush.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <asm/proc-fns.h>
19
20#if __LINUX_ARM_ARCH__ >= 6
21
22/*
23 * On ARMv6, we have the following structure in the Context ID:
24 *
25 * 31 7 0
26 * +-------------------------+-----------+
27 * | process ID | ASID |
28 * +-------------------------+-----------+
29 * | context ID |
30 * +-------------------------------------+
31 *
32 * The ASID is used to tag entries in the CPU caches and TLBs.
33 * The context ID is used by debuggers and trace logic, and
34 * should be unique within all running processes.
35 */
36#define ASID_BITS 8
37#define ASID_MASK ((~0) << ASID_BITS)
38
39extern unsigned int cpu_last_asid;
40
41void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
42void __new_context(struct mm_struct *mm);
43
44static inline void check_context(struct mm_struct *mm)
45{
46 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
47 __new_context(mm);
48}
49
50#define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0)
51
52#else
53
54#define check_context(mm) do { } while (0)
55#define init_new_context(tsk,mm) 0
56
57#endif
58
59#define destroy_context(mm) do { } while(0)
60
61/*
62 * This is called when "tsk" is about to enter lazy TLB mode.
63 *
64 * mm: describes the currently active mm context
65 * tsk: task which is entering lazy tlb
66 * cpu: cpu number which is entering lazy tlb
67 *
68 * tsk->mm will be NULL
69 */
70static inline void
71enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
72{
73}
74
75/*
76 * This is the actual mm switch as far as the scheduler
77 * is concerned. No registers are touched. We avoid
78 * calling the CPU specific function when the mm hasn't
79 * actually changed.
80 */
81static inline void
82switch_mm(struct mm_struct *prev, struct mm_struct *next,
83 struct task_struct *tsk)
84{
85 unsigned int cpu = smp_processor_id();
86
87 if (prev != next) {
88 cpu_set(cpu, next->cpu_vm_mask);
89 check_context(next);
90 cpu_switch_mm(next->pgd, next);
Russell King7e5e6e92005-11-03 20:32:45 +000091 if (cache_is_vivt())
92 cpu_clear(cpu, prev->cpu_vm_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 }
94}
95
96#define deactivate_mm(tsk,mm) do { } while (0)
97#define activate_mm(prev,next) switch_mm(prev, next, NULL)
98
99#endif