1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  *  arch/arm/include/asm/mmu_context.h
4  *
5  *  Copyright (C) 1996 Russell King.
6  *
7  *  Changelog:
8  *   27-06-1996	RMK	Created
9  */
10 #ifndef __ASM_ARM_MMU_CONTEXT_H
11 #define __ASM_ARM_MMU_CONTEXT_H
12 
13 #include <linux/compiler.h>
14 #include <linux/sched.h>
15 #include <linux/mm_types.h>
16 #include <linux/preempt.h>
17 
18 #include <asm/cacheflush.h>
19 #include <asm/cachetype.h>
20 #include <asm/proc-fns.h>
21 #include <asm/smp_plat.h>
22 #include <asm-generic/mm_hooks.h>
23 
24 void __check_vmalloc_seq(struct mm_struct *mm);
25 
26 #ifdef CONFIG_CPU_HAS_ASID
27 
28 void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
29 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)30 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
31 {
32 	atomic64_set(&mm->context.id, 0);
33 	return 0;
34 }
35 
36 #ifdef CONFIG_ARM_ERRATA_798181
37 void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
38 			     cpumask_t *mask);
39 #else  /* !CONFIG_ARM_ERRATA_798181 */
a15_erratum_get_cpumask(int this_cpu,struct mm_struct * mm,cpumask_t * mask)40 static inline void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
41 					   cpumask_t *mask)
42 {
43 }
44 #endif /* CONFIG_ARM_ERRATA_798181 */
45 
46 #else	/* !CONFIG_CPU_HAS_ASID */
47 
48 #ifdef CONFIG_MMU
49 
check_and_switch_context(struct mm_struct * mm,struct task_struct * tsk)50 static inline void check_and_switch_context(struct mm_struct *mm,
51 					    struct task_struct *tsk)
52 {
53 	if (unlikely(mm->context.vmalloc_seq != init_mm.context.vmalloc_seq))
54 		__check_vmalloc_seq(mm);
55 
56 	if (irqs_disabled())
57 		/*
58 		 * cpu_switch_mm() needs to flush the VIVT caches. To avoid
59 		 * high interrupt latencies, defer the call and continue
60 		 * running with the old mm. Since we only support UP systems
61 		 * on non-ASID CPUs, the old mm will remain valid until the
62 		 * finish_arch_post_lock_switch() call.
63 		 */
64 		mm->context.switch_pending = 1;
65 	else
66 		cpu_switch_mm(mm->pgd, mm);
67 }
68 
69 #ifndef MODULE
70 #define finish_arch_post_lock_switch \
71 	finish_arch_post_lock_switch
finish_arch_post_lock_switch(void)72 static inline void finish_arch_post_lock_switch(void)
73 {
74 	struct mm_struct *mm = current->mm;
75 
76 	if (mm && mm->context.switch_pending) {
77 		/*
78 		 * Preemption must be disabled during cpu_switch_mm() as we
79 		 * have some stateful cache flush implementations. Check
80 		 * switch_pending again in case we were preempted and the
81 		 * switch to this mm was already done.
82 		 */
83 		preempt_disable();
84 		if (mm->context.switch_pending) {
85 			mm->context.switch_pending = 0;
86 			cpu_switch_mm(mm->pgd, mm);
87 		}
88 		preempt_enable_no_resched();
89 	}
90 }
91 #endif /* !MODULE */
92 
93 #endif	/* CONFIG_MMU */
94 
95 static inline int
init_new_context(struct task_struct * tsk,struct mm_struct * mm)96 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
97 {
98 	return 0;
99 }
100 
101 
102 #endif	/* CONFIG_CPU_HAS_ASID */
103 
104 #define destroy_context(mm)		do { } while(0)
105 #define activate_mm(prev,next)		switch_mm(prev, next, NULL)
106 
107 /*
108  * This is called when "tsk" is about to enter lazy TLB mode.
109  *
110  * mm:  describes the currently active mm context
111  * tsk: task which is entering lazy tlb
112  * cpu: cpu number which is entering lazy tlb
113  *
114  * tsk->mm will be NULL
115  */
116 static inline void
enter_lazy_tlb(struct mm_struct * mm,struct task_struct * tsk)117 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
118 {
119 }
120 
121 /*
122  * This is the actual mm switch as far as the scheduler
123  * is concerned.  No registers are touched.  We avoid
124  * calling the CPU specific function when the mm hasn't
125  * actually changed.
126  */
127 static inline void
switch_mm(struct mm_struct * prev,struct mm_struct * next,struct task_struct * tsk)128 switch_mm(struct mm_struct *prev, struct mm_struct *next,
129 	  struct task_struct *tsk)
130 {
131 #ifdef CONFIG_MMU
132 	unsigned int cpu = smp_processor_id();
133 
134 	/*
135 	 * __sync_icache_dcache doesn't broadcast the I-cache invalidation,
136 	 * so check for possible thread migration and invalidate the I-cache
137 	 * if we're new to this CPU.
138 	 */
139 	if (cache_ops_need_broadcast() &&
140 	    !cpumask_empty(mm_cpumask(next)) &&
141 	    !cpumask_test_cpu(cpu, mm_cpumask(next)))
142 		__flush_icache_all();
143 
144 	if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
145 		check_and_switch_context(next, tsk);
146 		if (cache_is_vivt())
147 			cpumask_clear_cpu(cpu, mm_cpumask(prev));
148 	}
149 #endif
150 }
151 
152 #define deactivate_mm(tsk,mm)	do { } while (0)
153 
154 #endif
155