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 void free_initmem(void)
  33 {
  34 }
  35
  36 /*
  37  * ColdFire paging_init derived from sun3.
  38  */
  39 void __init paging_init(void)
  40 {
  41         pgd_t *pg_dir;
  42         pte_t *pg_table;
  43         unsigned long address, size;
  44         unsigned long next_pgtable, bootmem_end;
  45         unsigned long zones_size[MAX_NR_ZONES];
  46         enum zone_type zone;
  47         int i;
  48
  49         empty_zero_page = (void *) alloc_bootmem_pages(PAGE_SIZE);
  50         memset((void *) empty_zero_page, 0, PAGE_SIZE);
  51
  52         pg_dir = swapper_pg_dir;
  53         memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
  54
  55         size = num_pages * sizeof(pte_t);
  56         size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
  57         next_pgtable = (unsigned long) alloc_bootmem_pages(size);
  58
  59         bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
  60         pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
  61
  62         address = PAGE_OFFSET;
  63         while (address < (unsigned long)high_memory) {
  64                 pg_table = (pte_t *) next_pgtable;
  65                 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
  66                 pgd_val(*pg_dir) = (unsigned long) pg_table;
  67                 pg_dir++;
  68
  69                 /* now change pg_table to kernel virtual addresses */
  70                 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
  71                         pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
  72                         if (address >= (unsigned long) high_memory)
  73                                 pte_val(pte) = 0;
  74
  75                         set_pte(pg_table, pte);
  76                         address += PAGE_SIZE;
  77                 }
  78         }
  79
  80         current->mm = NULL;
  81
  82         for (zone = 0; zone < MAX_NR_ZONES; zone++)
  83                 zones_size[zone] = 0x0;
  84         zones_size[ZONE_DMA] = num_pages;
  85         free_area_init(zones_size);
  86 }
  87
  88 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
  89 {
  90         unsigned long flags, mmuar, mmutr;
  91         struct mm_struct *mm;
  92         pgd_t *pgd;
  93         pmd_t *pmd;
  94         pte_t *pte;
  95         int asid;
  96
  97         local_irq_save(flags);
  98
  99         mmuar = (dtlb) ? mmu_read(MMUAR) :
 100                 regs->pc + (extension_word * sizeof(long));
 101
 102         mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
 103         if (!mm) {
 104                 local_irq_restore(flags);
 105                 return -1;
 106         }
 107
 108         pgd = pgd_offset(mm, mmuar);
 109         if (pgd_none(*pgd))  {
 110                 local_irq_restore(flags);
 111                 return -1;
 112         }
 113
 114         pmd = pmd_offset(pgd, mmuar);
 115         if (pmd_none(*pmd)) {
 116                 local_irq_restore(flags);
 117                 return -1;
 118         }
 119
 120         pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
 121                                 : pte_offset_map(pmd, mmuar);
 122         if (pte_none(*pte) || !pte_present(*pte)) {
 123                 local_irq_restore(flags);
 124                 return -1;
 125         }
 126
 127         if (write) {
 128                 if (!pte_write(*pte)) {
 129                         local_irq_restore(flags);
 130                         return -1;
 131                 }
 132                 set_pte(pte, pte_mkdirty(*pte));
 133         }
 134
 135         set_pte(pte, pte_mkyoung(*pte));
 136         asid = mm->context & 0xff;
 137         if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
 138                 set_pte(pte, pte_wrprotect(*pte));
 139
 140         mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
 141         if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
 142                 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
 143         mmu_write(MMUTR, mmutr);
 144
 145         mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
 146                 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
 147
 148         if (dtlb)
 149                 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
 150         else
 151                 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
 152
 153         local_irq_restore(flags);
 154         return 0;
 155 }
 156
 157 /*
 158  * Initialize the context management stuff.
 159  * The following was taken from arch/ppc/mmu_context.c
 160  */
 161 void __init mmu_context_init(void)
 162 {
 163         /*
 164          * Some processors have too few contexts to reserve one for
 165          * init_mm, and require using context 0 for a normal task.
 166          * Other processors reserve the use of context zero for the kernel.
 167          * This code assumes FIRST_CONTEXT < 32.
 168          */
 169         context_map[0] = (1 << FIRST_CONTEXT) - 1;
 170         next_mmu_context = FIRST_CONTEXT;
 171         atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
 172 }
 173
 174 /*
 175  * Steal a context from a task that has one at the moment.
 176  * This is only used on 8xx and 4xx and we presently assume that
 177  * they don't do SMP.  If they do then thicfpgalloc.hs will have to check
 178  * whether the MM we steal is in use.
 179  * We also assume that this is only used on systems that don't
 180  * use an MMU hash table - this is true for 8xx and 4xx.
 181  * This isn't an LRU system, it just frees up each context in
 182  * turn (sort-of pseudo-random replacement :).  This would be the
 183  * place to implement an LRU scheme if anyone was motivated to do it.
 184  *  -- paulus
 185  */
 186 void steal_context(void)
 187 {
 188         struct mm_struct *mm;
 189         /*
 190          * free up context `next_mmu_context'
 191          * if we shouldn't free context 0, don't...
 192          */
 193         if (next_mmu_context < FIRST_CONTEXT)
 194                 next_mmu_context = FIRST_CONTEXT;
 195         mm = context_mm[next_mmu_context];
 196         flush_tlb_mm(mm);
 197         destroy_context(mm);
 198 }
 199