arch/m68k/mm/mcfmmu.c

   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