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