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Linux/arch/m68k/mm/mcfmmu.c

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  1 /*
  2  * Based upon linux/arch/m68k/mm/sun3mmu.c
  3  * Based upon linux/arch/ppc/mm/mmu_context.c
  4  *
  5  * Implementations of mm routines specific to the Coldfire MMU.
  6  *
  7  * Copyright (c) 2008 Freescale Semiconductor, Inc.
  8  */
  9 
 10 #include <linux/kernel.h>
 11 #include <linux/types.h>
 12 #include <linux/mm.h>
 13 #include <linux/init.h>
 14 #include <linux/string.h>
 15 #include <linux/bootmem.h>
 16 
 17 #include <asm/setup.h>
 18 #include <asm/page.h>
 19 #include <asm/pgtable.h>
 20 #include <asm/mmu_context.h>
 21 #include <asm/mcf_pgalloc.h>
 22 #include <asm/tlbflush.h>
 23 
 24 #define KMAPAREA(x)     ((x >= VMALLOC_START) && (x < KMAP_END))
 25 
 26 mm_context_t next_mmu_context;
 27 unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
 28 atomic_t nr_free_contexts;
 29 struct mm_struct *context_mm[LAST_CONTEXT+1];
 30 extern unsigned long num_pages;
 31 
 32 /*
 33  * ColdFire paging_init derived from sun3.
 34  */
 35 void __init paging_init(void)
 36 {
 37         pgd_t *pg_dir;
 38         pte_t *pg_table;
 39         unsigned long address, size;
 40         unsigned long next_pgtable, bootmem_end;
 41         unsigned long zones_size[MAX_NR_ZONES];
 42         enum zone_type zone;
 43         int i;
 44 
 45         empty_zero_page = (void *) alloc_bootmem_pages(PAGE_SIZE);
 46         memset((void *) empty_zero_page, 0, PAGE_SIZE);
 47 
 48         pg_dir = swapper_pg_dir;
 49         memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
 50 
 51         size = num_pages * sizeof(pte_t);
 52         size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
 53         next_pgtable = (unsigned long) alloc_bootmem_pages(size);
 54 
 55         bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
 56         pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
 57 
 58         address = PAGE_OFFSET;
 59         while (address < (unsigned long)high_memory) {
 60                 pg_table = (pte_t *) next_pgtable;
 61                 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
 62                 pgd_val(*pg_dir) = (unsigned long) pg_table;
 63                 pg_dir++;
 64 
 65                 /* now change pg_table to kernel virtual addresses */
 66                 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
 67                         pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
 68                         if (address >= (unsigned long) high_memory)
 69                                 pte_val(pte) = 0;
 70 
 71                         set_pte(pg_table, pte);
 72                         address += PAGE_SIZE;
 73                 }
 74         }
 75 
 76         current->mm = NULL;
 77 
 78         for (zone = 0; zone < MAX_NR_ZONES; zone++)
 79                 zones_size[zone] = 0x0;
 80         zones_size[ZONE_DMA] = num_pages;
 81         free_area_init(zones_size);
 82 }
 83 
 84 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
 85 {
 86         unsigned long flags, mmuar, mmutr;
 87         struct mm_struct *mm;
 88         pgd_t *pgd;
 89         pmd_t *pmd;
 90         pte_t *pte;
 91         int asid;
 92 
 93         local_irq_save(flags);
 94 
 95         mmuar = (dtlb) ? mmu_read(MMUAR) :
 96                 regs->pc + (extension_word * sizeof(long));
 97 
 98         mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
 99         if (!mm) {
100                 local_irq_restore(flags);
101                 return -1;
102         }
103 
104         pgd = pgd_offset(mm, mmuar);
105         if (pgd_none(*pgd))  {
106                 local_irq_restore(flags);
107                 return -1;
108         }
109 
110         pmd = pmd_offset(pgd, mmuar);
111         if (pmd_none(*pmd)) {
112                 local_irq_restore(flags);
113                 return -1;
114         }
115 
116         pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
117                                 : pte_offset_map(pmd, mmuar);
118         if (pte_none(*pte) || !pte_present(*pte)) {
119                 local_irq_restore(flags);
120                 return -1;
121         }
122 
123         if (write) {
124                 if (!pte_write(*pte)) {
125                         local_irq_restore(flags);
126                         return -1;
127                 }
128                 set_pte(pte, pte_mkdirty(*pte));
129         }
130 
131         set_pte(pte, pte_mkyoung(*pte));
132         asid = mm->context & 0xff;
133         if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
134                 set_pte(pte, pte_wrprotect(*pte));
135 
136         mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
137         if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
138                 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
139         mmu_write(MMUTR, mmutr);
140 
141         mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
142                 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
143 
144         if (dtlb)
145                 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
146         else
147                 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
148 
149         local_irq_restore(flags);
150         return 0;
151 }
152 
153 /*
154  * Initialize the context management stuff.
155  * The following was taken from arch/ppc/mmu_context.c
156  */
157 void __init mmu_context_init(void)
158 {
159         /*
160          * Some processors have too few contexts to reserve one for
161          * init_mm, and require using context 0 for a normal task.
162          * Other processors reserve the use of context zero for the kernel.
163          * This code assumes FIRST_CONTEXT < 32.
164          */
165         context_map[0] = (1 << FIRST_CONTEXT) - 1;
166         next_mmu_context = FIRST_CONTEXT;
167         atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
168 }
169 
170 /*
171  * Steal a context from a task that has one at the moment.
172  * This is only used on 8xx and 4xx and we presently assume that
173  * they don't do SMP.  If they do then thicfpgalloc.hs will have to check
174  * whether the MM we steal is in use.
175  * We also assume that this is only used on systems that don't
176  * use an MMU hash table - this is true for 8xx and 4xx.
177  * This isn't an LRU system, it just frees up each context in
178  * turn (sort-of pseudo-random replacement :).  This would be the
179  * place to implement an LRU scheme if anyone was motivated to do it.
180  *  -- paulus
181  */
182 void steal_context(void)
183 {
184         struct mm_struct *mm;
185         /*
186          * free up context `next_mmu_context'
187          * if we shouldn't free context 0, don't...
188          */
189         if (next_mmu_context < FIRST_CONTEXT)
190                 next_mmu_context = FIRST_CONTEXT;
191         mm = context_mm[next_mmu_context];
192         flush_tlb_mm(mm);
193         destroy_context(mm);
194 }
195 
196 

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