arch/cris/arch-v10/mm/tlb.c

   1 /*
   2  *  linux/arch/cris/arch-v10/mm/tlb.c
   3  *
   4  *  Low level TLB handling
   5  *
   6  *
   7  *  Copyright (C) 2000-2007  Axis Communications AB
   8  *
   9  *  Authors:   Bjorn Wesen (bjornw@axis.com)
  10  *
  11  */
  12
  13 #include <linux/mm_types.h>
  14
  15 #include <asm/tlb.h>
  16 #include <asm/mmu_context.h>
  17 #include <arch/svinto.h>
  18
  19 #define D(x)
  20
  21 /* The TLB can host up to 64 different mm contexts at the same time.
  22  * The running context is R_MMU_CONTEXT, and each TLB entry contains a
  23  * page_id that has to match to give a hit. In page_id_map, we keep track
  24  * of which mm's we have assigned which page_id's, so that we know when
  25  * to invalidate TLB entries.
  26  *
  27  * The last page_id is never running - it is used as an invalid page_id
  28  * so we can make TLB entries that will never match.
  29  *
  30  * Notice that we need to make the flushes atomic, otherwise an interrupt
  31  * handler that uses vmalloced memory might cause a TLB load in the middle
  32  * of a flush causing.
  33  */
  34
  35 /* invalidate all TLB entries */
  36
  37 void
  38 flush_tlb_all(void)
  39 {
  40         int i;
  41         unsigned long flags;
  42
  43         /* the vpn of i & 0xf is so we dont write similar TLB entries
  44          * in the same 4-way entry group. details...
  45          */
  46
  47         local_irq_save(flags);
  48         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
  49                 *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
  50                 *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
  51                               IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
  52
  53                 *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no       ) |
  54                               IO_STATE(R_TLB_LO, valid, no       ) |
  55                               IO_STATE(R_TLB_LO, kernel,no       ) |
  56                               IO_STATE(R_TLB_LO, we,    no       ) |
  57                               IO_FIELD(R_TLB_LO, pfn,   0        ) );
  58         }
  59         local_irq_restore(flags);
  60         D(printk("tlb: flushed all\n"));
  61 }
  62
  63 /* invalidate the selected mm context only */
  64
  65 void
  66 flush_tlb_mm(struct mm_struct *mm)
  67 {
  68         int i;
  69         int page_id = mm->context.page_id;
  70         unsigned long flags;
  71
  72         D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));
  73
  74         if(page_id == NO_CONTEXT)
  75                 return;
  76
  77         /* mark the TLB entries that match the page_id as invalid.
  78          * here we could also check the _PAGE_GLOBAL bit and NOT flush
  79          * global pages. is it worth the extra I/O ?
  80          */
  81
  82         local_irq_save(flags);
  83         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
  84                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
  85                 if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) {
  86                         *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
  87                                       IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
  88
  89                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
  90                                       IO_STATE(R_TLB_LO, valid, no  ) |
  91                                       IO_STATE(R_TLB_LO, kernel,no  ) |
  92                                       IO_STATE(R_TLB_LO, we,    no  ) |
  93                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
  94                 }
  95         }
  96         local_irq_restore(flags);
  97 }
  98
  99 /* invalidate a single page */
 100
 101 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 102 {
 103         struct mm_struct *mm = vma->vm_mm;
 104         int page_id = mm->context.page_id;
 105         int i;
 106         unsigned long flags;
 107
 108         D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));
 109
 110         if(page_id == NO_CONTEXT)
 111                 return;
 112
 113         addr &= PAGE_MASK; /* perhaps not necessary */
 114
 115         /* invalidate those TLB entries that match both the mm context
 116          * and the virtual address requested
 117          */
 118
 119         local_irq_save(flags);
 120         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
 121                 unsigned long tlb_hi;
 122                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
 123                 tlb_hi = *R_TLB_HI;
 124                 if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
 125                     (tlb_hi & PAGE_MASK) == addr) {
 126                         *R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
 127                                 addr; /* same addr as before works. */
 128
 129                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
 130                                       IO_STATE(R_TLB_LO, valid, no  ) |
 131                                       IO_STATE(R_TLB_LO, kernel,no  ) |
 132                                       IO_STATE(R_TLB_LO, we,    no  ) |
 133                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
 134                 }
 135         }
 136         local_irq_restore(flags);
 137 }
 138
 139 /*
 140  * Initialize the context related info for a new mm_struct
 141  * instance.
 142  */
 143
 144 int
 145 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 146 {
 147         mm->context.page_id = NO_CONTEXT;
 148         return 0;
 149 }
 150
 151 /* called in schedule() just before actually doing the switch_to */
 152
 153 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 154         struct task_struct *tsk)
 155 {
 156         if (prev != next) {
 157                 /* make sure we have a context */
 158                 get_mmu_context(next);
 159
 160                 /* remember the pgd for the fault handlers
 161                  * this is similar to the pgd register in some other CPU's.
 162                  * we need our own copy of it because current and active_mm
 163                  * might be invalid at points where we still need to derefer
 164                  * the pgd.
 165                  */
 166
 167                 per_cpu(current_pgd, smp_processor_id()) = next->pgd;
 168
 169                 /* switch context in the MMU */
 170
 171                 D(printk(KERN_DEBUG "switching mmu_context to %d (%p)\n",
 172                         next->context, next));
 173
 174                 *R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT,
 175                                           page_id, next->context.page_id);
 176         }
 177 }
 178