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