arch/xtensa/include/asm/mmu_context.h

   1 /*
   2  * Switch an MMU context.
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2001 - 2013 Tensilica Inc.
   9  */
  10
  11 #ifndef _XTENSA_MMU_CONTEXT_H
  12 #define _XTENSA_MMU_CONTEXT_H
  13
  14 #ifndef CONFIG_MMU
  15 #include <asm/nommu_context.h>
  16 #else
  17
  18 #include <linux/stringify.h>
  19 #include <linux/sched.h>
  20
  21 #include <asm/vectors.h>
  22
  23 #include <asm/pgtable.h>
  24 #include <asm/cacheflush.h>
  25 #include <asm/tlbflush.h>
  26 #include <asm-generic/mm_hooks.h>
  27 #include <asm-generic/percpu.h>
  28
  29 #if (XCHAL_HAVE_TLBS != 1)
  30 # error "Linux must have an MMU!"
  31 #endif
  32
  33 DECLARE_PER_CPU(unsigned long, asid_cache);
  34 #define cpu_asid_cache(cpu) per_cpu(asid_cache, cpu)
  35
  36 /*
  37  * NO_CONTEXT is the invalid ASID value that we don't ever assign to
  38  * any user or kernel context.  We use the reserved values in the
  39  * ASID_INSERT macro below.
  40  *
  41  * 0 invalid
  42  * 1 kernel
  43  * 2 reserved
  44  * 3 reserved
  45  * 4...255 available
  46  */
  47
  48 #define NO_CONTEXT      0
  49 #define ASID_USER_FIRST 4
  50 #define ASID_MASK       ((1 << XCHAL_MMU_ASID_BITS) - 1)
  51 #define ASID_INSERT(x)  (0x03020001 | (((x) & ASID_MASK) << 8))
  52
  53 void init_mmu(void);
  54
  55 static inline void set_rasid_register (unsigned long val)
  56 {
  57         __asm__ __volatile__ (" wsr %0, rasid\n\t"
  58                               " isync\n" : : "a" (val));
  59 }
  60
  61 static inline unsigned long get_rasid_register (void)
  62 {
  63         unsigned long tmp;
  64         __asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
  65         return tmp;
  66 }
  67
  68 static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu)
  69 {
  70         unsigned long asid = cpu_asid_cache(cpu);
  71         if ((++asid & ASID_MASK) == 0) {
  72                 /*
  73                  * Start new asid cycle; continue counting with next
  74                  * incarnation bits; skipping over 0, 1, 2, 3.
  75                  */
  76                 local_flush_tlb_all();
  77                 asid += ASID_USER_FIRST;
  78         }
  79         cpu_asid_cache(cpu) = asid;
  80         mm->context.asid[cpu] = asid;
  81         mm->context.cpu = cpu;
  82 }
  83
  84 static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
  85 {
  86         /*
  87          * Check if our ASID is of an older version and thus invalid.
  88          */
  89
  90         if (mm) {
  91                 unsigned long asid = mm->context.asid[cpu];
  92
  93                 if (asid == NO_CONTEXT ||
  94                                 ((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK))
  95                         get_new_mmu_context(mm, cpu);
  96         }
  97 }
  98
  99 static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
 100 {
 101         get_mmu_context(mm, cpu);
 102         set_rasid_register(ASID_INSERT(mm->context.asid[cpu]));
 103         invalidate_page_directory();
 104 }
 105
 106 /*
 107  * Initialize the context related info for a new mm_struct
 108  * instance.  Valid cpu values are 0..(NR_CPUS-1), so initializing
 109  * to -1 says the process has never run on any core.
 110  */
 111
 112 static inline int init_new_context(struct task_struct *tsk,
 113                 struct mm_struct *mm)
 114 {
 115         int cpu;
 116         for_each_possible_cpu(cpu) {
 117                 mm->context.asid[cpu] = NO_CONTEXT;
 118         }
 119         mm->context.cpu = -1;
 120         return 0;
 121 }
 122
 123 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 124                              struct task_struct *tsk)
 125 {
 126         unsigned int cpu = smp_processor_id();
 127         int migrated = next->context.cpu != cpu;
 128         /* Flush the icache if we migrated to a new core. */
 129         if (migrated) {
 130                 __invalidate_icache_all();
 131                 next->context.cpu = cpu;
 132         }
 133         if (migrated || prev != next)
 134                 activate_context(next, cpu);
 135 }
 136
 137 #define activate_mm(prev, next) switch_mm((prev), (next), NULL)
 138 #define deactivate_mm(tsk, mm)  do { } while (0)
 139
 140 /*
 141  * Destroy context related info for an mm_struct that is about
 142  * to be put to rest.
 143  */
 144 static inline void destroy_context(struct mm_struct *mm)
 145 {
 146         invalidate_page_directory();
 147 }
 148
 149
 150 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 151 {
 152         /* Nothing to do. */
 153
 154 }
 155
 156 #endif /* CONFIG_MMU */
 157 #endif /* _XTENSA_MMU_CONTEXT_H */