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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/cris/arch-v10/mm/tlb.c
   4  *
   5  *  Low level TLB handling
   6  *
   7  *
   8  *  Copyright (C) 2000-2007  Axis Communications AB
   9  *
  10  *  Authors:   Bjorn Wesen (bjornw@axis.com)
  11  *
  12  */
  13
  14 #include <linux/mm_types.h>
  15
  16 #include <asm/tlb.h>
  17 #include <asm/mmu_context.h>
  18 #include <arch/svinto.h>
  19
  20 #define D(x)
  21
  22 /* The TLB can host up to 64 different mm contexts at the same time.
  23  * The running context is R_MMU_CONTEXT, and each TLB entry contains a
  24  * page_id that has to match to give a hit. In page_id_map, we keep track
  25  * of which mm's we have assigned which page_id's, so that we know when
  26  * to invalidate TLB entries.
  27  *
  28  * The last page_id is never running - it is used as an invalid page_id
  29  * so we can make TLB entries that will never match.
  30  *
  31  * Notice that we need to make the flushes atomic, otherwise an interrupt
  32  * handler that uses vmalloced memory might cause a TLB load in the middle
  33  * of a flush causing.
  34  */
  35
  36 /* invalidate all TLB entries */
  37
  38 void
  39 flush_tlb_all(void)
  40 {
  41         int i;
  42         unsigned long flags;
  43
  44         /* the vpn of i & 0xf is so we dont write similar TLB entries
  45          * in the same 4-way entry group. details...
  46          */
  47
  48         local_irq_save(flags);
  49         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
  50                 *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
  51                 *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
  52                               IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
  53
  54                 *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no       ) |
  55                               IO_STATE(R_TLB_LO, valid, no       ) |
  56                               IO_STATE(R_TLB_LO, kernel,no       ) |
  57                               IO_STATE(R_TLB_LO, we,    no       ) |
  58                               IO_FIELD(R_TLB_LO, pfn,   0        ) );
  59         }
  60         local_irq_restore(flags);
  61         D(printk("tlb: flushed all\n"));
  62 }
  63
  64 /* invalidate the selected mm context only */
  65
  66 void
  67 flush_tlb_mm(struct mm_struct *mm)
  68 {
  69         int i;
  70         int page_id = mm->context.page_id;
  71         unsigned long flags;
  72
  73         D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));
  74
  75         if(page_id == NO_CONTEXT)
  76                 return;
  77
  78         /* mark the TLB entries that match the page_id as invalid.
  79          * here we could also check the _PAGE_GLOBAL bit and NOT flush
  80          * global pages. is it worth the extra I/O ?
  81          */
  82
  83         local_irq_save(flags);
  84         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
  85                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
  86                 if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) {
  87                         *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
  88                                       IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
  89
  90                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
  91                                       IO_STATE(R_TLB_LO, valid, no  ) |
  92                                       IO_STATE(R_TLB_LO, kernel,no  ) |
  93                                       IO_STATE(R_TLB_LO, we,    no  ) |
  94                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
  95                 }
  96         }
  97         local_irq_restore(flags);
  98 }
  99
 100 /* invalidate a single page */
 101
 102 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 103 {
 104         struct mm_struct *mm = vma->vm_mm;
 105         int page_id = mm->context.page_id;
 106         int i;
 107         unsigned long flags;
 108
 109         D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));
 110
 111         if(page_id == NO_CONTEXT)
 112                 return;
 113
 114         addr &= PAGE_MASK; /* perhaps not necessary */
 115
 116         /* invalidate those TLB entries that match both the mm context
 117          * and the virtual address requested
 118          */
 119
 120         local_irq_save(flags);
 121         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
 122                 unsigned long tlb_hi;
 123                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
 124                 tlb_hi = *R_TLB_HI;
 125                 if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
 126                     (tlb_hi & PAGE_MASK) == addr) {
 127                         *R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
 128                                 addr; /* same addr as before works. */
 129
 130                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
 131                                       IO_STATE(R_TLB_LO, valid, no  ) |
 132                                       IO_STATE(R_TLB_LO, kernel,no  ) |
 133                                       IO_STATE(R_TLB_LO, we,    no  ) |
 134                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
 135                 }
 136         }
 137         local_irq_restore(flags);
 138 }
 139
 140 /*
 141  * Initialize the context related info for a new mm_struct
 142  * instance.
 143  */
 144
 145 int
 146 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 147 {
 148         mm->context.page_id = NO_CONTEXT;
 149         return 0;
 150 }
 151
 152 /* called in schedule() just before actually doing the switch_to */
 153
 154 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 155         struct task_struct *tsk)
 156 {
 157         if (prev != next) {
 158                 /* make sure we have a context */
 159                 get_mmu_context(next);
 160
 161                 /* remember the pgd for the fault handlers
 162                  * this is similar to the pgd register in some other CPU's.
 163                  * we need our own copy of it because current and active_mm
 164                  * might be invalid at points where we still need to derefer
 165                  * the pgd.
 166                  */
 167
 168                 per_cpu(current_pgd, smp_processor_id()) = next->pgd;
 169
 170                 /* switch context in the MMU */
 171
 172                 D(printk(KERN_DEBUG "switching mmu_context to %d (%p)\n",
 173                         next->context, next));
 174
 175                 *R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT,
 176                                           page_id, next->context.page_id);
 177         }
 178 }
 179