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