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/mm_types.h>
  17 #include <linux/smp.h>
  18 #include <linux/slab.h>
  19
  20 #include <asm/cacheflush.h>
  21 #include <asm/dsemul.h>
  22 #include <asm/hazards.h>
  23 #include <asm/tlbflush.h>
  24 #include <asm-generic/mm_hooks.h>
  25
  26 #define htw_set_pwbase(pgd)                                             \
  27 do {                                                                    \
  28         if (cpu_has_htw) {                                              \
  29                 write_c0_pwbase(pgd);                                   \
  30                 back_to_back_c0_hazard();                               \
  31         }                                                               \
  32 } while (0)
  33
  34 extern void tlbmiss_handler_setup_pgd(unsigned long);
  35
  36 /* Note: This is also implemented with uasm in arch/mips/kvm/entry.c */
  37 #define TLBMISS_HANDLER_SETUP_PGD(pgd)                                  \
  38 do {                                                                    \
  39         tlbmiss_handler_setup_pgd((unsigned long)(pgd));                \
  40         htw_set_pwbase((unsigned long)pgd);                             \
  41 } while (0)
  42
  43 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
  44
  45 #define TLBMISS_HANDLER_RESTORE()                                       \
  46         write_c0_xcontext((unsigned long) smp_processor_id() <<         \
  47                           SMP_CPUID_REGSHIFT)
  48
  49 #define TLBMISS_HANDLER_SETUP()                                         \
  50         do {                                                            \
  51                 TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);              \
  52                 TLBMISS_HANDLER_RESTORE();                              \
  53         } while (0)
  54
  55 #else /* !CONFIG_MIPS_PGD_C0_CONTEXT: using  pgd_current*/
  56
  57 /*
  58  * For the fast tlb miss handlers, we keep a per cpu array of pointers
  59  * to the current pgd for each processor. Also, the proc. id is stuffed
  60  * into the context register.
  61  */
  62 extern unsigned long pgd_current[];
  63
  64 #define TLBMISS_HANDLER_RESTORE()                                       \
  65         write_c0_context((unsigned long) smp_processor_id() <<          \
  66                          SMP_CPUID_REGSHIFT)
  67
  68 #define TLBMISS_HANDLER_SETUP()                                         \
  69         TLBMISS_HANDLER_RESTORE();                                      \
  70         back_to_back_c0_hazard();                                       \
  71         TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
  72 #endif /* CONFIG_MIPS_PGD_C0_CONTEXT*/
  73
  74 /*
  75  *  All unused by hardware upper bits will be considered
  76  *  as a software asid extension.
  77  */
  78 static unsigned long asid_version_mask(unsigned int cpu)
  79 {
  80         unsigned long asid_mask = cpu_asid_mask(&cpu_data[cpu]);
  81
  82         return ~(asid_mask | (asid_mask - 1));
  83 }
  84
  85 static unsigned long asid_first_version(unsigned int cpu)
  86 {
  87         return ~asid_version_mask(cpu) + 1;
  88 }
  89
  90 #define cpu_context(cpu, mm)    ((mm)->context.asid[cpu])
  91 #define asid_cache(cpu)         (cpu_data[cpu].asid_cache)
  92 #define cpu_asid(cpu, mm) \
  93         (cpu_context((cpu), (mm)) & cpu_asid_mask(&cpu_data[cpu]))
  94
  95 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  96 {
  97 }
  98
  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         unsigned long asid = asid_cache(cpu);
 105
 106         if (!((asid += cpu_asid_inc()) & cpu_asid_mask(&cpu_data[cpu]))) {
 107                 if (cpu_has_vtag_icache)
 108                         flush_icache_all();
 109                 local_flush_tlb_all();  /* start new asid cycle */
 110                 if (!asid)              /* fix version if needed */
 111                         asid = asid_first_version(cpu);
 112         }
 113
 114         cpu_context(cpu, mm) = asid_cache(cpu) = asid;
 115 }
 116
 117 /*
 118  * Initialize the context related info for a new mm_struct
 119  * instance.
 120  */
 121 static inline int
 122 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 123 {
 124         int i;
 125
 126         for_each_possible_cpu(i)
 127                 cpu_context(i, mm) = 0;
 128
 129         atomic_set(&mm->context.fp_mode_switching, 0);
 130
 131         mm->context.bd_emupage_allocmap = NULL;
 132         spin_lock_init(&mm->context.bd_emupage_lock);
 133         init_waitqueue_head(&mm->context.bd_emupage_queue);
 134
 135         return 0;
 136 }
 137
 138 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 139                              struct task_struct *tsk)
 140 {
 141         unsigned int cpu = smp_processor_id();
 142         unsigned long flags;
 143         local_irq_save(flags);
 144
 145         htw_stop();
 146         /* Check if our ASID is of an older version and thus invalid */
 147         if ((cpu_context(cpu, next) ^ asid_cache(cpu)) & asid_version_mask(cpu))
 148                 get_new_mmu_context(next, cpu);
 149         write_c0_entryhi(cpu_asid(cpu, next));
 150         TLBMISS_HANDLER_SETUP_PGD(next->pgd);
 151
 152         /*
 153          * Mark current->active_mm as not "active" anymore.
 154          * We don't want to mislead possible IPI tlb flush routines.
 155          */
 156         cpumask_clear_cpu(cpu, mm_cpumask(prev));
 157         cpumask_set_cpu(cpu, mm_cpumask(next));
 158         htw_start();
 159
 160         local_irq_restore(flags);
 161 }
 162
 163 /*
 164  * Destroy context related info for an mm_struct that is about
 165  * to be put to rest.
 166  */
 167 static inline void destroy_context(struct mm_struct *mm)
 168 {
 169         dsemul_mm_cleanup(mm);
 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 */