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

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  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 <asm/tlb.h>
 14 #include <asm/mmu_context.h>
 15 #include <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_irq_save(flags);
 46         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
 47                 *R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
 48                 *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
 49                               IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
 50 
 51                 *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no       ) |
 52                               IO_STATE(R_TLB_LO, valid, no       ) |
 53                               IO_STATE(R_TLB_LO, kernel,no       ) |
 54                               IO_STATE(R_TLB_LO, we,    no       ) |
 55                               IO_FIELD(R_TLB_LO, pfn,   0        ) );
 56         }
 57         local_irq_restore(flags);
 58         D(printk("tlb: flushed all\n"));
 59 }
 60 
 61 /* invalidate the selected mm context only */
 62 
 63 void
 64 flush_tlb_mm(struct mm_struct *mm)
 65 {
 66         int i;
 67         int page_id = mm->context.page_id;
 68         unsigned long flags;
 69 
 70         D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));
 71 
 72         if(page_id == NO_CONTEXT)
 73                 return;
 74 
 75         /* mark the TLB entries that match the page_id as invalid.
 76          * here we could also check the _PAGE_GLOBAL bit and NOT flush
 77          * global pages. is it worth the extra I/O ?
 78          */
 79 
 80         local_irq_save(flags);
 81         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
 82                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
 83                 if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) {
 84                         *R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
 85                                       IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
 86 
 87                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
 88                                       IO_STATE(R_TLB_LO, valid, no  ) |
 89                                       IO_STATE(R_TLB_LO, kernel,no  ) |
 90                                       IO_STATE(R_TLB_LO, we,    no  ) |
 91                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
 92                 }
 93         }
 94         local_irq_restore(flags);
 95 }
 96 
 97 /* invalidate a single page */
 98 
 99 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
100 {
101         struct mm_struct *mm = vma->vm_mm;
102         int page_id = mm->context.page_id;
103         int i;
104         unsigned long flags;
105 
106         D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));
107 
108         if(page_id == NO_CONTEXT)
109                 return;
110 
111         addr &= PAGE_MASK; /* perhaps not necessary */
112 
113         /* invalidate those TLB entries that match both the mm context
114          * and the virtual address requested
115          */
116 
117         local_irq_save(flags);
118         for(i = 0; i < NUM_TLB_ENTRIES; i++) {
119                 unsigned long tlb_hi;
120                 *R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
121                 tlb_hi = *R_TLB_HI;
122                 if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
123                     (tlb_hi & PAGE_MASK) == addr) {
124                         *R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
125                                 addr; /* same addr as before works. */
126 
127                         *R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
128                                       IO_STATE(R_TLB_LO, valid, no  ) |
129                                       IO_STATE(R_TLB_LO, kernel,no  ) |
130                                       IO_STATE(R_TLB_LO, we,    no  ) |
131                                       IO_FIELD(R_TLB_LO, pfn,   0   ) );
132                 }
133         }
134         local_irq_restore(flags);
135 }
136 
137 /*
138  * Initialize the context related info for a new mm_struct
139  * instance.
140  */
141 
142 int
143 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
144 {
145         mm->context.page_id = NO_CONTEXT;
146         return 0;
147 }
148 
149 /* called in schedule() just before actually doing the switch_to */
150 
151 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
152         struct task_struct *tsk)
153 {
154         if (prev != next) {
155                 /* make sure we have a context */
156                 get_mmu_context(next);
157 
158                 /* remember the pgd for the fault handlers
159                  * this is similar to the pgd register in some other CPU's.
160                  * we need our own copy of it because current and active_mm
161                  * might be invalid at points where we still need to derefer
162                  * the pgd.
163                  */
164 
165                 per_cpu(current_pgd, smp_processor_id()) = next->pgd;
166 
167                 /* switch context in the MMU */
168 
169                 D(printk(KERN_DEBUG "switching mmu_context to %d (%p)\n",
170                         next->context, next));
171 
172                 *R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT,
173                                           page_id, next->context.page_id);
174         }
175 }
176 
177 

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