arch/cris/arch-v32/mm/tlb.c

   1 /*
   2  * Low level TLB handling.
   3  *
   4  * Copyright (C) 2000-2003, Axis Communications AB.
   5  *
   6  * Authors:   Bjorn Wesen <bjornw@axis.com>
   7  *            Tobias Anderberg <tobiasa@axis.com>, CRISv32 port.
   8  */
   9
  10 #include <asm/tlb.h>
  11 #include <asm/mmu_context.h>
  12 #include <asm/arch/hwregs/asm/mmu_defs_asm.h>
  13 #include <asm/arch/hwregs/supp_reg.h>
  14
  15 #define UPDATE_TLB_SEL_IDX(val)                                 \
  16 do {                                                            \
  17         unsigned long tlb_sel;                                  \
  18                                                                 \
  19         tlb_sel = REG_FIELD(mmu, rw_mm_tlb_sel, idx, val);      \
  20         SUPP_REG_WR(RW_MM_TLB_SEL, tlb_sel);                    \
  21 } while(0)
  22
  23 #define UPDATE_TLB_HILO(tlb_hi, tlb_lo)         \
  24 do {                                            \
  25         SUPP_REG_WR(RW_MM_TLB_HI, tlb_hi);      \
  26         SUPP_REG_WR(RW_MM_TLB_LO, tlb_lo);      \
  27 } while(0)
  28
  29 /*
  30  * The TLB can host up to 256 different mm contexts at the same time. The running
  31  * context is found in the PID register. Each TLB entry contains a page_id that
  32  * has to match the PID register to give a hit. page_id_map keeps track of which
  33  * mm's is assigned to which page_id's, making sure it's known when to
  34  * invalidate TLB entries.
  35  *
  36  * The last page_id is never running, it is used as an invalid page_id so that
  37  * it's possible to make TLB entries that will nerver match.
  38  *
  39  * Note; the flushes needs to be atomic otherwise an interrupt hander that uses
  40  * vmalloc'ed memory might cause a TLB load in the middle of a flush.
  41  */
  42
  43 /* Flush all TLB entries. */
  44 void
  45 __flush_tlb_all(void)
  46 {
  47         int i;
  48         int mmu;
  49         unsigned long flags;
  50         unsigned long mmu_tlb_hi;
  51         unsigned long mmu_tlb_sel;
  52
  53         /*
  54          * Mask with 0xf so similar TLB entries aren't written in the same 4-way
  55          * entry group.
  56          */
  57         local_save_flags(flags);
  58         local_irq_disable();
  59
  60         for (mmu = 1; mmu <= 2; mmu++) {
  61                 SUPP_BANK_SEL(mmu); /* Select the MMU */
  62                 for (i = 0; i < NUM_TLB_ENTRIES; i++) {
  63                         /* Store invalid entry */
  64                         mmu_tlb_sel = REG_FIELD(mmu, rw_mm_tlb_sel, idx, i);
  65
  66                         mmu_tlb_hi = (REG_FIELD(mmu, rw_mm_tlb_hi, pid, INVALID_PAGEID)
  67                                     | REG_FIELD(mmu, rw_mm_tlb_hi, vpn, i & 0xf));
  68
  69                         SUPP_REG_WR(RW_MM_TLB_SEL, mmu_tlb_sel);
  70                         SUPP_REG_WR(RW_MM_TLB_HI, mmu_tlb_hi);
  71                         SUPP_REG_WR(RW_MM_TLB_LO, 0);
  72                 }
  73         }
  74
  75         local_irq_restore(flags);
  76 }
  77
  78 /* Flush an entire user address space. */
  79 void
  80 __flush_tlb_mm(struct mm_struct *mm)
  81 {
  82         int i;
  83         int mmu;
  84         unsigned long flags;
  85         unsigned long page_id;
  86         unsigned long tlb_hi;
  87         unsigned long mmu_tlb_hi;
  88
  89         page_id = mm->context.page_id;
  90
  91         if (page_id == NO_CONTEXT)
  92                 return;
  93
  94         /* Mark the TLB entries that match the page_id as invalid. */
  95         local_save_flags(flags);
  96         local_irq_disable();
  97
  98         for (mmu = 1; mmu <= 2; mmu++) {
  99                 SUPP_BANK_SEL(mmu);
 100                 for (i = 0; i < NUM_TLB_ENTRIES; i++) {
 101                         UPDATE_TLB_SEL_IDX(i);
 102
 103                         /* Get the page_id */
 104                         SUPP_REG_RD(RW_MM_TLB_HI, tlb_hi);
 105
 106                         /* Check if the page_id match. */
 107                         if ((tlb_hi & 0xff) == page_id) {
 108                                 mmu_tlb_hi = (REG_FIELD(mmu, rw_mm_tlb_hi, pid,
 109                                                         INVALID_PAGEID)
 110                                             | REG_FIELD(mmu, rw_mm_tlb_hi, vpn,
 111                                                         i & 0xf));
 112
 113                                 UPDATE_TLB_HILO(mmu_tlb_hi, 0);
 114                         }
 115                 }
 116         }
 117
 118         local_irq_restore(flags);
 119 }
 120
 121 /* Invalidate a single page. */
 122 void
 123 __flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 124 {
 125         int i;
 126         int mmu;
 127         unsigned long page_id;
 128         unsigned long flags;
 129         unsigned long tlb_hi;
 130         unsigned long mmu_tlb_hi;
 131
 132         page_id = vma->vm_mm->context.page_id;
 133
 134         if (page_id == NO_CONTEXT)
 135                 return;
 136
 137         addr &= PAGE_MASK;
 138
 139         /*
 140          * Invalidate those TLB entries that match both the mm context and the
 141          * requested virtual address.
 142          */
 143         local_save_flags(flags);
 144         local_irq_disable();
 145
 146         for (mmu = 1; mmu <= 2; mmu++) {
 147                 SUPP_BANK_SEL(mmu);
 148                 for (i = 0; i < NUM_TLB_ENTRIES; i++) {
 149                         UPDATE_TLB_SEL_IDX(i);
 150                         SUPP_REG_RD(RW_MM_TLB_HI, tlb_hi);
 151
 152                         /* Check if page_id and address matches */
 153                         if (((tlb_hi & 0xff) == page_id) &&
 154                             ((tlb_hi & PAGE_MASK) == addr)) {
 155                                 mmu_tlb_hi = REG_FIELD(mmu, rw_mm_tlb_hi, pid,
 156                                                        INVALID_PAGEID) | addr;
 157
 158                                 UPDATE_TLB_HILO(mmu_tlb_hi, 0);
 159                         }
 160                 }
 161         }
 162
 163         local_irq_restore(flags);
 164 }
 165
 166 /*
 167  * Initialize the context related info for a new mm_struct
 168  * instance.
 169  */
 170
 171 int
 172 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 173 {
 174         mm->context.page_id = NO_CONTEXT;
 175         return 0;
 176 }
 177
 178 static DEFINE_SPINLOCK(mmu_context_lock);
 179
 180 /* Called in schedule() just before actually doing the switch_to. */
 181 void
 182 switch_mm(struct mm_struct *prev, struct mm_struct *next,
 183           struct task_struct *tsk)
 184 {
 185         int cpu = smp_processor_id();
 186
 187         /* Make sure there is a MMU context. */
 188         spin_lock(&mmu_context_lock);
 189         get_mmu_context(next);
 190         cpu_set(cpu, next->cpu_vm_mask);
 191         spin_unlock(&mmu_context_lock);
 192
 193         /*
 194          * Remember the pgd for the fault handlers. Keep a seperate copy of it
 195          * because current and active_mm might be invalid at points where
 196          * there's still a need to derefer the pgd.
 197          */
 198         per_cpu(current_pgd, cpu) = next->pgd;
 199
 200         /* Switch context in the MMU. */
 201         if (tsk && task_thread_info(tsk))
 202         {
 203           SPEC_REG_WR(SPEC_REG_PID, next->context.page_id | task_thread_info(tsk)->tls);
 204         }
 205         else
 206         {
 207           SPEC_REG_WR(SPEC_REG_PID, next->context.page_id);
 208         }
 209 }
 210