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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
|
/*
* linux/arch/arm/mm/context.c
*
* Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/percpu.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
static DEFINE_SPINLOCK(cpu_asid_lock);
unsigned int cpu_last_asid = ASID_FIRST_VERSION;
#ifdef CONFIG_SMP
DEFINE_PER_CPU(struct mm_struct *, current_mm);
#endif
/*
* We fork()ed a process, and we need a new context for the child
* to run in. We reserve version 0 for initial tasks so we will
* always allocate an ASID. The ASID 0 is reserved for the TTBR
* register changing sequence.
*/
void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
mm->context.id = 0;
spin_lock_init(&mm->context.id_lock);
}
static void flush_context(void)
{
/* set the reserved ASID before flushing the TLB */
asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (0));
isb();
local_flush_tlb_all();
if (icache_is_vivt_asid_tagged()) {
__flush_icache_all();
dsb();
}
}
#ifdef CONFIG_SMP
static void set_mm_context(struct mm_struct *mm, unsigned int asid)
{
unsigned long flags;
/*
* Locking needed for multi-threaded applications where the
* same mm->context.id could be set from different CPUs during
* the broadcast. This function is also called via IPI so the
* mm->context.id_lock has to be IRQ-safe.
*/
spin_lock_irqsave(&mm->context.id_lock, flags);
if (likely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) {
/*
* Old version of ASID found. Set the new one and
* reset mm_cpumask(mm).
*/
mm->context.id = asid;
cpumask_clear(mm_cpumask(mm));
}
spin_unlock_irqrestore(&mm->context.id_lock, flags);
/*
* Set the mm_cpumask(mm) bit for the current CPU.
*/
cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
}
/*
* Reset the ASID on the current CPU. This function call is broadcast
* from the CPU handling the ASID rollover and holding cpu_asid_lock.
*/
static void reset_context(void *info)
{
unsigned int asid;
unsigned int cpu = smp_processor_id();
struct mm_struct *mm = per_cpu(current_mm, cpu);
/*
* Check if a current_mm was set on this CPU as it might still
* be in the early booting stages and using the reserved ASID.
*/
if (!mm)
return;
smp_rmb();
asid = cpu_last_asid + cpu;
flush_context();
set_mm_context(mm, asid);
/* set the new ASID */
asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (mm->context.id));
isb();
}
#else
static inline void set_mm_context(struct mm_struct *mm, unsigned int asid)
{
mm->context.id = asid;
cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id()));
}
#endif
void __new_context(struct mm_struct *mm)
{
unsigned int asid;
spin_lock(&cpu_asid_lock);
#ifdef CONFIG_SMP
/*
* Check the ASID again, in case the change was broadcast from
* another CPU before we acquired the lock.
*/
if (unlikely(((mm->context.id ^ cpu_last_asid) >> ASID_BITS) == 0)) {
cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
spin_unlock(&cpu_asid_lock);
return;
}
#endif
/*
* At this point, it is guaranteed that the current mm (with
* an old ASID) isn't active on any other CPU since the ASIDs
* are changed simultaneously via IPI.
*/
asid = ++cpu_last_asid;
if (asid == 0)
asid = cpu_last_asid = ASID_FIRST_VERSION;
/*
* If we've used up all our ASIDs, we need
* to start a new version and flush the TLB.
*/
if (unlikely((asid & ~ASID_MASK) == 0)) {
asid = cpu_last_asid + smp_processor_id();
flush_context();
#ifdef CONFIG_SMP
smp_wmb();
smp_call_function(reset_context, NULL, 1);
#endif
cpu_last_asid += NR_CPUS - 1;
}
set_mm_context(mm, asid);
spin_unlock(&cpu_asid_lock);
}
|
