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