arch/s390/include/asm/mmu_context.h

   1 /*
   2  *  S390 version
   3  *
   4  *  Derived from "include/asm-i386/mmu_context.h"
   5  */
   6
   7 #ifndef __S390_MMU_CONTEXT_H
   8 #define __S390_MMU_CONTEXT_H
   9
  10 #include <asm/pgalloc.h>
  11 #include <asm/uaccess.h>
  12 #include <asm/tlbflush.h>
  13 #include <asm/ctl_reg.h>
  14
  15 static inline int init_new_context(struct task_struct *tsk,
  16                                    struct mm_struct *mm)
  17 {
  18         spin_lock_init(&mm->context.list_lock);
  19         INIT_LIST_HEAD(&mm->context.pgtable_list);
  20         INIT_LIST_HEAD(&mm->context.gmap_list);
  21         cpumask_clear(&mm->context.cpu_attach_mask);
  22         atomic_set(&mm->context.attach_count, 0);
  23         mm->context.flush_mm = 0;
  24 #ifdef CONFIG_PGSTE
  25         mm->context.alloc_pgste = page_table_allocate_pgste;
  26         mm->context.has_pgste = 0;
  27         mm->context.use_skey = 0;
  28 #endif
  29         switch (mm->context.asce_limit) {
  30         case 1UL << 42:
  31                 /*
  32                  * forked 3-level task, fall through to set new asce with new
  33                  * mm->pgd
  34                  */
  35         case 0:
  36                 /* context created by exec, set asce limit to 4TB */
  37                 mm->context.asce_limit = STACK_TOP_MAX;
  38                 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
  39                                    _ASCE_USER_BITS | _ASCE_TYPE_REGION3;
  40                 break;
  41         case 1UL << 53:
  42                 /* forked 4-level task, set new asce with new mm->pgd */
  43                 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
  44                                    _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
  45                 break;
  46         case 1UL << 31:
  47                 /* forked 2-level compat task, set new asce with new mm->pgd */
  48                 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
  49                                    _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
  50                 /* pgd_alloc() did not increase mm->nr_pmds */
  51                 mm_inc_nr_pmds(mm);
  52         }
  53         crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
  54         return 0;
  55 }
  56
  57 #define destroy_context(mm)             do { } while (0)
  58
  59 static inline void set_user_asce(struct mm_struct *mm)
  60 {
  61         S390_lowcore.user_asce = mm->context.asce;
  62         if (current->thread.mm_segment.ar4)
  63                 __ctl_load(S390_lowcore.user_asce, 7, 7);
  64         set_cpu_flag(CIF_ASCE);
  65 }
  66
  67 static inline void clear_user_asce(void)
  68 {
  69         S390_lowcore.user_asce = S390_lowcore.kernel_asce;
  70
  71         __ctl_load(S390_lowcore.user_asce, 1, 1);
  72         __ctl_load(S390_lowcore.user_asce, 7, 7);
  73 }
  74
  75 static inline void load_kernel_asce(void)
  76 {
  77         unsigned long asce;
  78
  79         __ctl_store(asce, 1, 1);
  80         if (asce != S390_lowcore.kernel_asce)
  81                 __ctl_load(S390_lowcore.kernel_asce, 1, 1);
  82         set_cpu_flag(CIF_ASCE);
  83 }
  84
  85 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  86                              struct task_struct *tsk)
  87 {
  88         int cpu = smp_processor_id();
  89
  90         S390_lowcore.user_asce = next->context.asce;
  91         if (prev == next)
  92                 return;
  93         if (MACHINE_HAS_TLB_LC)
  94                 cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);
  95         /* Clear old ASCE by loading the kernel ASCE. */
  96         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
  97         __ctl_load(S390_lowcore.kernel_asce, 7, 7);
  98         atomic_inc(&next->context.attach_count);
  99         atomic_dec(&prev->context.attach_count);
 100         if (MACHINE_HAS_TLB_LC)
 101                 cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
 102 }
 103
 104 #define finish_arch_post_lock_switch finish_arch_post_lock_switch
 105 static inline void finish_arch_post_lock_switch(void)
 106 {
 107         struct task_struct *tsk = current;
 108         struct mm_struct *mm = tsk->mm;
 109
 110         load_kernel_asce();
 111         if (mm) {
 112                 preempt_disable();
 113                 while (atomic_read(&mm->context.attach_count) >> 16)
 114                         cpu_relax();
 115
 116                 cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
 117                 if (mm->context.flush_mm)
 118                         __tlb_flush_mm(mm);
 119                 preempt_enable();
 120         }
 121         set_fs(current->thread.mm_segment);
 122 }
 123
 124 #define enter_lazy_tlb(mm,tsk)  do { } while (0)
 125 #define deactivate_mm(tsk,mm)   do { } while (0)
 126
 127 static inline void activate_mm(struct mm_struct *prev,
 128                                struct mm_struct *next)
 129 {
 130         switch_mm(prev, next, current);
 131         cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
 132         set_user_asce(next);
 133 }
 134
 135 static inline void arch_dup_mmap(struct mm_struct *oldmm,
 136                                  struct mm_struct *mm)
 137 {
 138 }
 139
 140 static inline void arch_exit_mmap(struct mm_struct *mm)
 141 {
 142 }
 143
 144 static inline void arch_unmap(struct mm_struct *mm,
 145                         struct vm_area_struct *vma,
 146                         unsigned long start, unsigned long end)
 147 {
 148 }
 149
 150 static inline void arch_bprm_mm_init(struct mm_struct *mm,
 151                                      struct vm_area_struct *vma)
 152 {
 153 }
 154
 155 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 156                 bool write, bool execute, bool foreign)
 157 {
 158         /* by default, allow everything */
 159         return true;
 160 }
 161
 162 static inline bool arch_pte_access_permitted(pte_t pte, bool write)
 163 {
 164         /* by default, allow everything */
 165         return true;
 166 }
 167 #endif /* __S390_MMU_CONTEXT_H */