1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
/* MN10300 MMU context management
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Modified by David Howells (dhowells@redhat.com)
* - Derived from include/asm-m32r/mmu_context.h
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*
*
* This implements an algorithm to provide TLB PID mappings to provide
* selective access to the TLB for processes, thus reducing the number of TLB
* flushes required.
*
* Note, however, that the M32R algorithm is technically broken as it does not
* handle version wrap-around, and could, theoretically, have a problem with a
* very long lived program that sleeps long enough for the version number to
* wrap all the way around so that its TLB mappings appear valid once again.
*/
#ifndef _ASM_MMU_CONTEXT_H
#define _ASM_MMU_CONTEXT_H
#include <asm/atomic.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm-generic/mm_hooks.h>
#define MMU_CONTEXT_TLBPID_MASK 0x000000ffUL
#define MMU_CONTEXT_VERSION_MASK 0xffffff00UL
#define MMU_CONTEXT_FIRST_VERSION 0x00000100UL
#define MMU_NO_CONTEXT 0x00000000UL
extern unsigned long mmu_context_cache[NR_CPUS];
#define mm_context(mm) (mm->context.tlbpid[smp_processor_id()])
#define enter_lazy_tlb(mm, tsk) do {} while (0)
#ifdef CONFIG_SMP
#define cpu_ran_vm(cpu, mm) \
cpumask_set_cpu((cpu), mm_cpumask(mm))
#define cpu_maybe_ran_vm(cpu, mm) \
cpumask_test_and_set_cpu((cpu), mm_cpumask(mm))
#else
#define cpu_ran_vm(cpu, mm) do {} while (0)
#define cpu_maybe_ran_vm(cpu, mm) true
#endif /* CONFIG_SMP */
/*
* allocate an MMU context
*/
static inline unsigned long allocate_mmu_context(struct mm_struct *mm)
{
unsigned long *pmc = &mmu_context_cache[smp_processor_id()];
unsigned long mc = ++(*pmc);
if (!(mc & MMU_CONTEXT_TLBPID_MASK)) {
/* we exhausted the TLB PIDs of this version on this CPU, so we
* flush this CPU's TLB in its entirety and start new cycle */
local_flush_tlb_all();
/* fix the TLB version if needed (we avoid version #0 so as to
* distingush MMU_NO_CONTEXT) */
if (!mc)
*pmc = mc = MMU_CONTEXT_FIRST_VERSION;
}
mm_context(mm) = mc;
return mc;
}
/*
* get an MMU context if one is needed
*/
static inline unsigned long get_mmu_context(struct mm_struct *mm)
{
unsigned long mc = MMU_NO_CONTEXT, cache;
if (mm) {
cache = mmu_context_cache[smp_processor_id()];
mc = mm_context(mm);
/* if we have an old version of the context, replace it */
if ((mc ^ cache) & MMU_CONTEXT_VERSION_MASK)
mc = allocate_mmu_context(mm);
}
return mc;
}
/*
* initialise the context related info for a new mm_struct instance
*/
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
int num_cpus = NR_CPUS, i;
for (i = 0; i < num_cpus; i++)
mm->context.tlbpid[i] = MMU_NO_CONTEXT;
return 0;
}
/*
* destroy context related info for an mm_struct that is about to be put to
* rest
*/
#define destroy_context(mm) do { } while (0)
/*
* after we have set current->mm to a new value, this activates the context for
* the new mm so we see the new mappings.
*/
static inline void activate_context(struct mm_struct *mm, int cpu)
{
PIDR = get_mmu_context(mm) & MMU_CONTEXT_TLBPID_MASK;
}
/*
* change between virtual memory sets
*/
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
int cpu = smp_processor_id();
if (prev != next) {
cpu_ran_vm(cpu, next);
activate_context(next, cpu);
PTBR = (unsigned long) next->pgd;
} else if (!cpu_maybe_ran_vm(cpu, next)) {
activate_context(next, cpu);
}
}
#define deactivate_mm(tsk, mm) do {} while (0)
#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
#endif /* _ASM_MMU_CONTEXT_H */
|
