1 /*
2 * arch/arm/include/asm/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 <linux/sched.h>
18 #include <linux/preempt.h>
19 #include <asm/cacheflush.h>
20 #include <asm/cachetype.h>
21 #include <asm/proc-fns.h>
22 #include <asm/smp_plat.h>
23 #include <asm-generic/mm_hooks.h>
24
25 void __check_vmalloc_seq(struct mm_struct *mm);
26
27 #ifdef CONFIG_CPU_HAS_ASID
28
29 void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
30 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)31 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
32 {
33 atomic64_set(&mm->context.id, 0);
34 return 0;
35 }
36
37 #ifdef CONFIG_ARM_ERRATA_798181
38 void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
39 cpumask_t *mask);
40 #else /* !CONFIG_ARM_ERRATA_798181 */
a15_erratum_get_cpumask(int this_cpu,struct mm_struct * mm,cpumask_t * mask)41 static inline void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
42 cpumask_t *mask)
43 {
44 }
45 #endif /* CONFIG_ARM_ERRATA_798181 */
46
47 #else /* !CONFIG_CPU_HAS_ASID */
48
49 #ifdef CONFIG_MMU
50
check_and_switch_context(struct mm_struct * mm,struct task_struct * tsk)51 static inline void check_and_switch_context(struct mm_struct *mm,
52 struct task_struct *tsk)
53 {
54 if (unlikely(mm->context.vmalloc_seq != init_mm.context.vmalloc_seq))
55 __check_vmalloc_seq(mm);
56
57 if (irqs_disabled())
58 /*
59 * cpu_switch_mm() needs to flush the VIVT caches. To avoid
60 * high interrupt latencies, defer the call and continue
61 * running with the old mm. Since we only support UP systems
62 * on non-ASID CPUs, the old mm will remain valid until the
63 * finish_arch_post_lock_switch() call.
64 */
65 mm->context.switch_pending = 1;
66 else
67 cpu_switch_mm(mm->pgd, mm);
68 }
69
70 #ifndef MODULE
71 #define finish_arch_post_lock_switch \
72 finish_arch_post_lock_switch
finish_arch_post_lock_switch(void)73 static inline void finish_arch_post_lock_switch(void)
74 {
75 struct mm_struct *mm = current->mm;
76
77 if (mm && mm->context.switch_pending) {
78 /*
79 * Preemption must be disabled during cpu_switch_mm() as we
80 * have some stateful cache flush implementations. Check
81 * switch_pending again in case we were preempted and the
82 * switch to this mm was already done.
83 */
84 preempt_disable();
85 if (mm->context.switch_pending) {
86 mm->context.switch_pending = 0;
87 cpu_switch_mm(mm->pgd, mm);
88 }
89 preempt_enable_no_resched();
90 }
91 }
92 #endif /* !MODULE */
93
94 #endif /* CONFIG_MMU */
95
96 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)97 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
98 {
99 return 0;
100 }
101
102
103 #endif /* CONFIG_CPU_HAS_ASID */
104
105 #define destroy_context(mm) do { } while(0)
106 #define activate_mm(prev,next) switch_mm(prev, next, NULL)
107
108 /*
109 * This is called when "tsk" is about to enter lazy TLB mode.
110 *
111 * mm: describes the currently active mm context
112 * tsk: task which is entering lazy tlb
113 * cpu: cpu number which is entering lazy tlb
114 *
115 * tsk->mm will be NULL
116 */
117 static inline void
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)118 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
119 {
120 }
121
122 /*
123 * This is the actual mm switch as far as the scheduler
124 * is concerned. No registers are touched. We avoid
125 * calling the CPU specific function when the mm hasn't
126 * actually changed.
127 */
128 static inline void
switch_mm(struct mm_struct * prev,struct mm_struct * next,struct task_struct * tsk)129 switch_mm(struct mm_struct *prev, struct mm_struct *next,
130 struct task_struct *tsk)
131 {
132 #ifdef CONFIG_MMU
133 unsigned int cpu = smp_processor_id();
134
135 /*
136 * __sync_icache_dcache doesn't broadcast the I-cache invalidation,
137 * so check for possible thread migration and invalidate the I-cache
138 * if we're new to this CPU.
139 */
140 if (cache_ops_need_broadcast() &&
141 !cpumask_empty(mm_cpumask(next)) &&
142 !cpumask_test_cpu(cpu, mm_cpumask(next)))
143 __flush_icache_all();
144
145 if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
146 check_and_switch_context(next, tsk);
147 if (cache_is_vivt())
148 cpumask_clear_cpu(cpu, mm_cpumask(prev));
149 }
150 #endif
151 }
152
153 #define deactivate_mm(tsk,mm) do { } while (0)
154
155 #endif
156