arch/arm/include/asm/mmu_context.h

   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
  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 */
  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
  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
  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
  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
 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
 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