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   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 <arch/hwregs/asm/mmu_defs_asm.h>
  13 #include <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_irq_save(flags);
  58
  59         for (mmu = 1; mmu <= 2; mmu++) {
  60                 SUPP_BANK_SEL(mmu); /* Select the MMU */
  61                 for (i = 0; i < NUM_TLB_ENTRIES; i++) {
  62                         /* Store invalid entry */
  63                         mmu_tlb_sel = REG_FIELD(mmu, rw_mm_tlb_sel, idx, i);
  64
  65                         mmu_tlb_hi = (REG_FIELD(mmu, rw_mm_tlb_hi, pid, INVALID_PAGEID)
  66                                     | REG_FIELD(mmu, rw_mm_tlb_hi, vpn, i & 0xf));
  67
  68                         SUPP_REG_WR(RW_MM_TLB_SEL, mmu_tlb_sel);
  69                         SUPP_REG_WR(RW_MM_TLB_HI, mmu_tlb_hi);
  70                         SUPP_REG_WR(RW_MM_TLB_LO, 0);
  71                 }
  72         }
  73
  74         local_irq_restore(flags);
  75 }
  76
  77 /* Flush an entire user address space. */
  78 void
  79 __flush_tlb_mm(struct mm_struct *mm)
  80 {
  81         int i;
  82         int mmu;
  83         unsigned long flags;
  84         unsigned long page_id;
  85         unsigned long tlb_hi;
  86         unsigned long mmu_tlb_hi;
  87
  88         page_id = mm->context.page_id;
  89
  90         if (page_id == NO_CONTEXT)
  91                 return;
  92
  93         /* Mark the TLB entries that match the page_id as invalid. */
  94         local_irq_save(flags);
  95
  96         for (mmu = 1; mmu <= 2; mmu++) {
  97                 SUPP_BANK_SEL(mmu);
  98                 for (i = 0; i < NUM_TLB_ENTRIES; i++) {
  99                         UPDATE_TLB_SEL_IDX(i);
 100
 101                         /* Get the page_id */
 102                         SUPP_REG_RD(RW_MM_TLB_HI, tlb_hi);
 103
 104                         /* Check if the page_id match. */
 105                         if ((tlb_hi & 0xff) == page_id) {
 106                                 mmu_tlb_hi = (REG_FIELD(mmu, rw_mm_tlb_hi, pid,
 107                                                         INVALID_PAGEID)
 108                                             | REG_FIELD(mmu, rw_mm_tlb_hi, vpn,
 109                                                         i & 0xf));
 110
 111                                 UPDATE_TLB_HILO(mmu_tlb_hi, 0);
 112                         }
 113                 }
 114         }
 115
 116         local_irq_restore(flags);
 117 }
 118
 119 /* Invalidate a single page. */
 120 void
 121 __flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 122 {
 123         int i;
 124         int mmu;
 125         unsigned long page_id;
 126         unsigned long flags;
 127         unsigned long tlb_hi;
 128         unsigned long mmu_tlb_hi;
 129
 130         page_id = vma->vm_mm->context.page_id;
 131
 132         if (page_id == NO_CONTEXT)
 133                 return;
 134
 135         addr &= PAGE_MASK;
 136
 137         /*
 138          * Invalidate those TLB entries that match both the mm context and the
 139          * requested virtual address.
 140          */
 141         local_irq_save(flags);
 142
 143         for (mmu = 1; mmu <= 2; mmu++) {
 144                 SUPP_BANK_SEL(mmu);
 145                 for (i = 0; i < NUM_TLB_ENTRIES; i++) {
 146                         UPDATE_TLB_SEL_IDX(i);
 147                         SUPP_REG_RD(RW_MM_TLB_HI, tlb_hi);
 148
 149                         /* Check if page_id and address matches */
 150                         if (((tlb_hi & 0xff) == page_id) &&
 151                             ((tlb_hi & PAGE_MASK) == addr)) {
 152                                 mmu_tlb_hi = REG_FIELD(mmu, rw_mm_tlb_hi, pid,
 153                                                        INVALID_PAGEID) | addr;
 154
 155                                 UPDATE_TLB_HILO(mmu_tlb_hi, 0);
 156                         }
 157                 }
 158         }
 159
 160         local_irq_restore(flags);
 161 }
 162
 163 /*
 164  * Initialize the context related info for a new mm_struct
 165  * instance.
 166  */
 167
 168 int
 169 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 170 {
 171         mm->context.page_id = NO_CONTEXT;
 172         return 0;
 173 }
 174
 175 static DEFINE_SPINLOCK(mmu_context_lock);
 176
 177 /* Called in schedule() just before actually doing the switch_to. */
 178 void
 179 switch_mm(struct mm_struct *prev, struct mm_struct *next,
 180           struct task_struct *tsk)
 181 {
 182         if (prev != next) {
 183                 int cpu = smp_processor_id();
 184
 185                 /* Make sure there is a MMU context. */
 186                 spin_lock(&mmu_context_lock);
 187                 get_mmu_context(next);
 188                 cpumask_set_cpu(cpu, mm_cpumask(next));
 189                 spin_unlock(&mmu_context_lock);
 190
 191                 /*
 192                  * Remember the pgd for the fault handlers. Keep a seperate
 193                  * copy of it because current and active_mm might be invalid
 194                  * at points where * there's still a need to derefer the pgd.
 195                  */
 196                 per_cpu(current_pgd, cpu) = next->pgd;
 197
 198                 /* Switch context in the MMU. */
 199                 if (tsk && task_thread_info(tsk)) {
 200                         SPEC_REG_WR(SPEC_REG_PID, next->context.page_id |
 201                                 task_thread_info(tsk)->tls);
 202                 } else {
 203                         SPEC_REG_WR(SPEC_REG_PID, next->context.page_id);
 204                 }
 205         }
 206 }
 207