arch/xtensa/include/asm/mmu_context.h

   1 /*
   2  * include/asm-xtensa/mmu_context.h
   3  *
   4  * Switch an MMU context.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  * Copyright (C) 2001 - 2005 Tensilica Inc.
  11  */
  12
  13 #ifndef _XTENSA_MMU_CONTEXT_H
  14 #define _XTENSA_MMU_CONTEXT_H
  15
  16 #ifndef CONFIG_MMU
  17 #include <asm/nommu_context.h>
  18 #else
  19
  20 #include <linux/stringify.h>
  21 #include <linux/sched.h>
  22
  23 #include <variant/core.h>
  24
  25 #include <asm/pgtable.h>
  26 #include <asm/cacheflush.h>
  27 #include <asm/tlbflush.h>
  28 #include <asm-generic/mm_hooks.h>
  29
  30 #if (XCHAL_HAVE_TLBS != 1)
  31 # error "Linux must have an MMU!"
  32 #endif
  33
  34 extern unsigned long asid_cache;
  35
  36 /*
  37  * NO_CONTEXT is the invalid ASID value that we don't ever assign to
  38  * any user or kernel context.
  39  *
  40  * 0 invalid
  41  * 1 kernel
  42  * 2 reserved
  43  * 3 reserved
  44  * 4...255 available
  45  */
  46
  47 #define NO_CONTEXT      0
  48 #define ASID_USER_FIRST 4
  49 #define ASID_MASK       ((1 << XCHAL_MMU_ASID_BITS) - 1)
  50 #define ASID_INSERT(x)  (0x03020001 | (((x) & ASID_MASK) << 8))
  51
  52 static inline void set_rasid_register (unsigned long val)
  53 {
  54         __asm__ __volatile__ (" wsr %0, "__stringify(RASID)"\n\t"
  55                               " isync\n" : : "a" (val));
  56 }
  57
  58 static inline unsigned long get_rasid_register (void)
  59 {
  60         unsigned long tmp;
  61         __asm__ __volatile__ (" rsr %0,"__stringify(RASID)"\n\t" : "=a" (tmp));
  62         return tmp;
  63 }
  64
  65 static inline void
  66 __get_new_mmu_context(struct mm_struct *mm)
  67 {
  68         extern void flush_tlb_all(void);
  69         if (! (++asid_cache & ASID_MASK) ) {
  70                 flush_tlb_all(); /* start new asid cycle */
  71                 asid_cache += ASID_USER_FIRST;
  72         }
  73         mm->context = asid_cache;
  74 }
  75
  76 static inline void
  77 __load_mmu_context(struct mm_struct *mm)
  78 {
  79         set_rasid_register(ASID_INSERT(mm->context));
  80         invalidate_page_directory();
  81 }
  82
  83 /*
  84  * Initialize the context related info for a new mm_struct
  85  * instance.
  86  */
  87
  88 static inline int
  89 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  90 {
  91         mm->context = NO_CONTEXT;
  92         return 0;
  93 }
  94
  95 /*
  96  * After we have set current->mm to a new value, this activates
  97  * the context for the new mm so we see the new mappings.
  98  */
  99 static inline void
 100 activate_mm(struct mm_struct *prev, struct mm_struct *next)
 101 {
 102         /* Unconditionally get a new ASID.  */
 103
 104         __get_new_mmu_context(next);
 105         __load_mmu_context(next);
 106 }
 107
 108
 109 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 110                              struct task_struct *tsk)
 111 {
 112         unsigned long asid = asid_cache;
 113
 114         /* Check if our ASID is of an older version and thus invalid */
 115
 116         if (next->context == NO_CONTEXT || ((next->context^asid) & ~ASID_MASK))
 117                 __get_new_mmu_context(next);
 118
 119         __load_mmu_context(next);
 120 }
 121
 122 #define deactivate_mm(tsk, mm)  do { } while(0)
 123
 124 /*
 125  * Destroy context related info for an mm_struct that is about
 126  * to be put to rest.
 127  */
 128 static inline void destroy_context(struct mm_struct *mm)
 129 {
 130         invalidate_page_directory();
 131 }
 132
 133
 134 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 135 {
 136         /* Nothing to do. */
 137
 138 }
 139
 140 #endif /* CONFIG_MMU */
 141 #endif /* _XTENSA_MMU_CONTEXT_H */