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) 2000-2002  Axis Communications AB
   8  *
   9  *  Authors:   Bjorn Wesen (bjornw@axis.com)
  10  *
  11  */
  12
  13 #include <asm/tlb.h>
  14 #include <asm/mmu_context.h>
  15 #include <asm/arch/svinto.h>
  16
  17 #define D(x)
  18
  19 /* The TLB can host up to 64 different mm contexts at the same time.
  20  * The running context is R_MMU_CONTEXT, and each TLB entry contains a
  21  * page_id that has to match to give a hit. In page_id_map, we keep track
  22  * of which mm's we have assigned which page_id's, so that we know when
  23  * to invalidate TLB entries.
  24  *
  25  * The last page_id is never running - it is used as an invalid page_id
  26  * so we can make TLB entries that will never match.
  27  *
  28  * Notice that we need to make the flushes atomic, otherwise an interrupt
  29  * handler that uses vmalloced memory might cause a TLB load in the middle
  30  * of a flush causing.
  31  */
  32
  33 /* invalidate all TLB entries */
  34
  35 void
  36 flush_tlb_all(void)
  37 {
  38         int i;
  39         unsigned long flags;
  40
  41         /* the vpn of i & 0xf is so we dont write similar TLB entries
  42          * in the same 4-way entry group. details..
  43          */
  44
  45         local_save_flags(flags);
  46         local_irq_disable();
  47         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
  48                 *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
  49                 *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
  50                               IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
  51
  52                 *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no       ) |
  53                               IO_STATE(R_TLB_LO, valid, no       ) |
  54                               IO_STATE(R_TLB_LO, kernel,no       ) |
  55                               IO_STATE(R_TLB_LO, we,    no       ) |
  56                               IO_FIELD(R_TLB_LO, pfn,   0        ) );
  57         }
  58         local_irq_restore(flags);
  59         D(printk("tlb: flushed all\n"));
  60 }
  61
  62 /* invalidate the selected mm context only */
  63
  64 void
  65 flush_tlb_mm(struct mm_struct *mm)
  66 {
  67         int i;
  68         int page_id = mm->context.page_id;
  69         unsigned long flags;
  70
  71         D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));
  72
  73         if(page_id == NO_CONTEXT)
  74                 return;
  75
  76         /* mark the TLB entries that match the page_id as invalid.
  77          * here we could also check the _PAGE_GLOBAL bit and NOT flush
  78          * global pages. is it worth the extra I/O ?
  79          */
  80
  81         local_save_flags(flags);
  82         local_irq_disable();
  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
 102 flush_tlb_page(struct vm_area_struct *vma,
 103                unsigned long addr)
 104 {
 105         struct mm_struct *mm = vma->vm_mm;
 106         int page_id = mm->context.page_id;
 107         int i;
 108         unsigned long flags;
 109
 110         D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));
 111
 112         if(page_id == NO_CONTEXT)
 113                 return;
 114
 115         addr &= PAGE_MASK; /* perhaps not necessary */
 116
 117         /* invalidate those TLB entries that match both the mm context
 118          * and the virtual address requested
 119          */
 120
 121         local_save_flags(flags);
 122         local_irq_disable();
 123         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
 124                 unsigned long tlb_hi;
 125                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
 126                 tlb_hi = *R_TLB_HI;
 127                 if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
 128                     (tlb_hi & PAGE_MASK) == addr) {
 129                         *R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
 130                                 addr; /* same addr as before works. */
 131
 132                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
 133                                       IO_STATE(R_TLB_LO, valid, no  ) |
 134                                       IO_STATE(R_TLB_LO, kernel,no  ) |
 135                                       IO_STATE(R_TLB_LO, we,    no  ) |
 136                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
 137                 }
 138         }
 139         local_irq_restore(flags);
 140 }
 141
 142 /* dump the entire TLB for debug purposes */
 143
 144 #if 0
 145 void
 146 dump_tlb_all(void)
 147 {
 148         int i;
 149         unsigned long flags;
 150
 151         printk("TLB dump. LO is: pfn | reserved | global | valid | kernel | we  |\n");
 152
 153         local_save_flags(flags);
 154         local_irq_disable();
 155         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
 156                 *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
 157                 printk("Entry %d: HI 0x%08lx, LO 0x%08lx\n",
 158                        i, *R_TLB_HI, *R_TLB_LO);
 159         }
 160         local_irq_restore(flags);
 161 }
 162 #endif
 163
 164 /*
 165  * Initialize the context related info for a new mm_struct
 166  * instance.
 167  */
 168
 169 int
 170 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 171 {
 172         mm->context.page_id = NO_CONTEXT;
 173         return 0;
 174 }
 175
 176 /* called in schedule() just before actually doing the switch_to */
 177
 178 void
 179 switch_mm(struct mm_struct *prev, struct mm_struct *next,
 180           struct task_struct *tsk)
 181 {
 182         /* make sure we have a context */
 183
 184         get_mmu_context(next);
 185
 186         /* remember the pgd for the fault handlers
 187          * this is similar to the pgd register in some other CPU's.
 188          * we need our own copy of it because current and active_mm
 189          * might be invalid at points where we still need to derefer
 190          * the pgd.
 191          */
 192
 193         per_cpu(current_pgd, smp_processor_id()) = next->pgd;
 194
 195         /* switch context in the MMU */
 196
 197         D(printk("switching mmu_context to %d (%p)\n", next->context, next));
 198
 199         *R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT, page_id, next->context.page_id);
 200 }
 201