kernel/arch/mips/include/asm/mmu_context.h

   1 /*
   2  * Switch a 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) 1996, 1997, 1998, 1999 by Ralf Baechle
   9  * Copyright (C) 1999 Silicon Graphics, Inc.
  10  */
  11 #ifndef _ASM_MMU_CONTEXT_H
  12 #define _ASM_MMU_CONTEXT_H
  13
  14 #include <linux/errno.h>
  15 #include <linux/sched.h>
  16 #include <linux/smp.h>
  17 #include <linux/slab.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/hazards.h>
  20 #include <asm/tlbflush.h>
  21 #include <asm-generic/mm_hooks.h>
  22
  23 #define htw_set_pwbase(pgd)                                             \
  24 do {                                                                    \
  25         if (cpu_has_htw) {                                              \
  26                 write_c0_pwbase(pgd);                                   \
  27                 back_to_back_c0_hazard();                               \
  28         }                                                               \
  29 } while (0)
  30
  31 #define TLBMISS_HANDLER_SETUP_PGD(pgd)                                  \
  32 do {                                                                    \
  33         extern void tlbmiss_handler_setup_pgd(unsigned long);           \
  34         tlbmiss_handler_setup_pgd((unsigned long)(pgd));                \
  35         htw_set_pwbase((unsigned long)pgd);                             \
  36 } while (0)
  37
  38 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
  39
  40 #define TLBMISS_HANDLER_RESTORE()                                       \
  41         write_c0_xcontext((unsigned long) smp_processor_id() <<         \
  42                           SMP_CPUID_REGSHIFT)
  43
  44 #define TLBMISS_HANDLER_SETUP()                                         \
  45         do {                                                            \
  46                 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);              \
  47                 TLBMISS_HANDLER_RESTORE();                              \
  48         } while (0)
  49
  50 #else /* !CONFIG_MIPS_PGD_C0_CONTEXT: using  pgd_current*/
  51
  52 /*
  53  * For the fast tlb miss handlers, we keep a per cpu array of pointers
  54  * to the current pgd for each processor. Also, the proc. id is stuffed
  55  * into the context register.
  56  */
  57 extern unsigned long pgd_current[];
  58
  59 #define TLBMISS_HANDLER_RESTORE()                                       \
  60         write_c0_context((unsigned long) smp_processor_id() <<          \
  61                          SMP_CPUID_REGSHIFT)
  62
  63 #define TLBMISS_HANDLER_SETUP()                                         \
  64         TLBMISS_HANDLER_RESTORE();                                      \
  65         back_to_back_c0_hazard();                                       \
  66         TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
  67 #endif /* CONFIG_MIPS_PGD_C0_CONTEXT*/
  68 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
  69
  70 #define ASID_INC        0x40
  71 #define ASID_MASK       0xfc0
  72
  73 #elif defined(CONFIG_CPU_R8000)
  74
  75 #define ASID_INC        0x10
  76 #define ASID_MASK       0xff0
  77
  78 #else /* FIXME: not correct for R6000 */
  79
  80 #define ASID_INC        0x1
  81 #define ASID_MASK       0xff
  82
  83 #endif
  84
  85 #define cpu_context(cpu, mm)    ((mm)->context.asid[cpu])
  86 #define cpu_asid(cpu, mm)       (cpu_context((cpu), (mm)) & ASID_MASK)
  87 #define asid_cache(cpu)         (cpu_data[cpu].asid_cache)
  88
  89 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  90 {
  91 }
  92
  93 /*
  94  *  All unused by hardware upper bits will be considered
  95  *  as a software asid extension.
  96  */
  97 #define ASID_VERSION_MASK  ((unsigned long)~(ASID_MASK|(ASID_MASK-1)))
  98 #define ASID_FIRST_VERSION ((unsigned long)(~ASID_VERSION_MASK) + 1)
  99
 100 /* Normal, classic MIPS get_new_mmu_context */
 101 static inline void
 102 get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
 103 {
 104         extern void kvm_local_flush_tlb_all(void);
 105         unsigned long asid = asid_cache(cpu);
 106
 107         if (! ((asid += ASID_INC) & ASID_MASK) ) {
 108                 if (cpu_has_vtag_icache)
 109                         flush_icache_all();
 110 #ifdef CONFIG_KVM
 111                 kvm_local_flush_tlb_all();      /* start new asid cycle */
 112 #else
 113                 local_flush_tlb_all();  /* start new asid cycle */
 114 #endif
 115                 if (!asid)              /* fix version if needed */
 116                         asid = ASID_FIRST_VERSION;
 117         }
 118
 119         cpu_context(cpu, mm) = asid_cache(cpu) = asid;
 120 }
 121
 122 /*
 123  * Initialize the context related info for a new mm_struct
 124  * instance.
 125  */
 126 static inline int
 127 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 128 {
 129         int i;
 130
 131         for_each_possible_cpu(i)
 132                 cpu_context(i, mm) = 0;
 133
 134         atomic_set(&mm->context.fp_mode_switching, 0);
 135
 136         return 0;
 137 }
 138
 139 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 140                              struct task_struct *tsk)
 141 {
 142         unsigned int cpu = smp_processor_id();
 143         unsigned long flags;
 144         local_irq_save(flags);
 145
 146         htw_stop();
 147         /* Check if our ASID is of an older version and thus invalid */
 148         if ((cpu_context(cpu, next) ^ asid_cache(cpu)) & ASID_VERSION_MASK)
 149                 get_new_mmu_context(next, cpu);
 150         write_c0_entryhi(cpu_asid(cpu, next));
 151         TLBMISS_HANDLER_SETUP_PGD(next->pgd);
 152
 153         /*
 154          * Mark current->active_mm as not "active" anymore.
 155          * We don't want to mislead possible IPI tlb flush routines.
 156          */
 157         cpumask_clear_cpu(cpu, mm_cpumask(prev));
 158         cpumask_set_cpu(cpu, mm_cpumask(next));
 159         htw_start();
 160
 161         local_irq_restore(flags);
 162 }
 163
 164 /*
 165  * Destroy context related info for an mm_struct that is about
 166  * to be put to rest.
 167  */
 168 static inline void destroy_context(struct mm_struct *mm)
 169 {
 170 }
 171
 172 #define deactivate_mm(tsk, mm)  do { } while (0)
 173
 174 /*
 175  * After we have set current->mm to a new value, this activates
 176  * the context for the new mm so we see the new mappings.
 177  */
 178 static inline void
 179 activate_mm(struct mm_struct *prev, struct mm_struct *next)
 180 {
 181         unsigned long flags;
 182         unsigned int cpu = smp_processor_id();
 183
 184         local_irq_save(flags);
 185
 186         htw_stop();
 187         /* Unconditionally get a new ASID.  */
 188         get_new_mmu_context(next, cpu);
 189
 190         write_c0_entryhi(cpu_asid(cpu, next));
 191         TLBMISS_HANDLER_SETUP_PGD(next->pgd);
 192
 193         /* mark mmu ownership change */
 194         cpumask_clear_cpu(cpu, mm_cpumask(prev));
 195         cpumask_set_cpu(cpu, mm_cpumask(next));
 196         htw_start();
 197
 198         local_irq_restore(flags);
 199 }
 200
 201 /*
 202  * If mm is currently active_mm, we can't really drop it.  Instead,
 203  * we will get a new one for it.
 204  */
 205 static inline void
 206 drop_mmu_context(struct mm_struct *mm, unsigned cpu)
 207 {
 208         unsigned long flags;
 209
 210         local_irq_save(flags);
 211         htw_stop();
 212
 213         if (cpumask_test_cpu(cpu, mm_cpumask(mm)))  {
 214                 get_new_mmu_context(mm, cpu);
 215                 write_c0_entryhi(cpu_asid(cpu, mm));
 216         } else {
 217                 /* will get a new context next time */
 218                 cpu_context(cpu, mm) = 0;
 219         }
 220         htw_start();
 221         local_irq_restore(flags);
 222 }
 223
 224 #endif /* _ASM_MMU_CONTEXT_H */