arch/sh/include/asm/mmu_context.h

   1 /*
   2  * Copyright (C) 1999 Niibe Yutaka
   3  * Copyright (C) 2003 - 2007 Paul Mundt
   4  *
   5  * ASID handling idea taken from MIPS implementation.
   6  */
   7 #ifndef __ASM_SH_MMU_CONTEXT_H
   8 #define __ASM_SH_MMU_CONTEXT_H
   9
  10 #ifdef __KERNEL__
  11 #include <cpu/mmu_context.h>
  12 #include <asm/tlbflush.h>
  13 #include <asm/uaccess.h>
  14 #include <asm/io.h>
  15 #include <asm-generic/mm_hooks.h>
  16
  17 /*
  18  * The MMU "context" consists of two things:
  19  *    (a) TLB cache version (or round, cycle whatever expression you like)
  20  *    (b) ASID (Address Space IDentifier)
  21  */
  22 #ifdef CONFIG_CPU_HAS_PTEAEX
  23 #define MMU_CONTEXT_ASID_MASK           0x0000ffff
  24 #else
  25 #define MMU_CONTEXT_ASID_MASK           0x000000ff
  26 #endif
  27
  28 #define MMU_CONTEXT_VERSION_MASK        (~0UL & ~MMU_CONTEXT_ASID_MASK)
  29 #define MMU_CONTEXT_FIRST_VERSION       (MMU_CONTEXT_ASID_MASK + 1)
  30
  31 /* Impossible ASID value, to differentiate from NO_CONTEXT. */
  32 #define MMU_NO_ASID                     MMU_CONTEXT_FIRST_VERSION
  33 #define NO_CONTEXT                      0UL
  34
  35 #define asid_cache(cpu)         (cpu_data[cpu].asid_cache)
  36
  37 #ifdef CONFIG_MMU
  38 #define cpu_context(cpu, mm)    ((mm)->context.id[cpu])
  39
  40 #define cpu_asid(cpu, mm)       \
  41         (cpu_context((cpu), (mm)) & MMU_CONTEXT_ASID_MASK)
  42
  43 /*
  44  * Virtual Page Number mask
  45  */
  46 #define MMU_VPN_MASK    0xfffff000
  47
  48 #if defined(CONFIG_SUPERH32)
  49 #include <asm/mmu_context_32.h>
  50 #else
  51 #include <asm/mmu_context_64.h>
  52 #endif
  53
  54 /*
  55  * Get MMU context if needed.
  56  */
  57 static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
  58 {
  59         unsigned long asid = asid_cache(cpu);
  60
  61         /* Check if we have old version of context. */
  62         if (((cpu_context(cpu, mm) ^ asid) & MMU_CONTEXT_VERSION_MASK) == 0)
  63                 /* It's up to date, do nothing */
  64                 return;
  65
  66         /* It's old, we need to get new context with new version. */
  67         if (!(++asid & MMU_CONTEXT_ASID_MASK)) {
  68                 /*
  69                  * We exhaust ASID of this version.
  70                  * Flush all TLB and start new cycle.
  71                  */
  72                 local_flush_tlb_all();
  73
  74 #ifdef CONFIG_SUPERH64
  75                 /*
  76                  * The SH-5 cache uses the ASIDs, requiring both the I and D
  77                  * cache to be flushed when the ASID is exhausted. Weak.
  78                  */
  79                 flush_cache_all();
  80 #endif
  81
  82                 /*
  83                  * Fix version; Note that we avoid version #0
  84                  * to distinguish NO_CONTEXT.
  85                  */
  86                 if (!asid)
  87                         asid = MMU_CONTEXT_FIRST_VERSION;
  88         }
  89
  90         cpu_context(cpu, mm) = asid_cache(cpu) = asid;
  91 }
  92
  93 /*
  94  * Initialize the context related info for a new mm_struct
  95  * instance.
  96  */
  97 static inline int init_new_context(struct task_struct *tsk,
  98                                    struct mm_struct *mm)
  99 {
 100         int i;
 101
 102         for_each_online_cpu(i)
 103                 cpu_context(i, mm) = NO_CONTEXT;
 104
 105         return 0;
 106 }
 107
 108 /*
 109  * After we have set current->mm to a new value, this activates
 110  * the context for the new mm so we see the new mappings.
 111  */
 112 static inline void activate_context(struct mm_struct *mm, unsigned int cpu)
 113 {
 114         get_mmu_context(mm, cpu);
 115         set_asid(cpu_asid(cpu, mm));
 116 }
 117
 118 static inline void switch_mm(struct mm_struct *prev,
 119                              struct mm_struct *next,
 120                              struct task_struct *tsk)
 121 {
 122         unsigned int cpu = smp_processor_id();
 123
 124         if (likely(prev != next)) {
 125                 cpumask_set_cpu(cpu, mm_cpumask(next));
 126                 set_TTB(next->pgd);
 127                 activate_context(next, cpu);
 128         } else
 129                 if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)))
 130                         activate_context(next, cpu);
 131 }
 132
 133 #define activate_mm(prev, next)         switch_mm((prev),(next),NULL)
 134 #define deactivate_mm(tsk,mm)           do { } while (0)
 135 #define enter_lazy_tlb(mm,tsk)          do { } while (0)
 136
 137 #else
 138
 139 #define set_asid(asid)                  do { } while (0)
 140 #define get_asid()                      (0)
 141 #define cpu_asid(cpu, mm)               ({ (void)cpu; NO_CONTEXT; })
 142 #define switch_and_save_asid(asid)      (0)
 143 #define set_TTB(pgd)                    do { } while (0)
 144 #define get_TTB()                       (0)
 145
 146 #include <asm-generic/mmu_context.h>
 147
 148 #endif /* CONFIG_MMU */
 149
 150 #if defined(CONFIG_CPU_SH3) || defined(CONFIG_CPU_SH4)
 151 /*
 152  * If this processor has an MMU, we need methods to turn it off/on ..
 153  * paging_init() will also have to be updated for the processor in
 154  * question.
 155  */
 156 static inline void enable_mmu(void)
 157 {
 158         unsigned int cpu = smp_processor_id();
 159
 160         /* Enable MMU */
 161         __raw_writel(MMU_CONTROL_INIT, MMUCR);
 162         ctrl_barrier();
 163
 164         if (asid_cache(cpu) == NO_CONTEXT)
 165                 asid_cache(cpu) = MMU_CONTEXT_FIRST_VERSION;
 166
 167         set_asid(asid_cache(cpu) & MMU_CONTEXT_ASID_MASK);
 168 }
 169
 170 static inline void disable_mmu(void)
 171 {
 172         unsigned long cr;
 173
 174         cr = __raw_readl(MMUCR);
 175         cr &= ~MMU_CONTROL_INIT;
 176         __raw_writel(cr, MMUCR);
 177
 178         ctrl_barrier();
 179 }
 180 #else
 181 /*
 182  * MMU control handlers for processors lacking memory
 183  * management hardware.
 184  */
 185 #define enable_mmu()    do { } while (0)
 186 #define disable_mmu()   do { } while (0)
 187 #endif
 188
 189 #endif /* __KERNEL__ */
 190 #endif /* __ASM_SH_MMU_CONTEXT_H */