arch/m68k/mm/mcfmmu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Based upon linux/arch/m68k/mm/sun3mmu.c
   4  * Based upon linux/arch/ppc/mm/mmu_context.c
   5  *
   6  * Implementations of mm routines specific to the Coldfire MMU.
   7  *
   8  * Copyright (c) 2008 Freescale Semiconductor, Inc.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/types.h>
  13 #include <linux/mm.h>
  14 #include <linux/init.h>
  15 #include <linux/string.h>
  16 #include <linux/bootmem.h>
  17
  18 #include <asm/setup.h>
  19 #include <asm/page.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/mmu_context.h>
  22 #include <asm/mcf_pgalloc.h>
  23 #include <asm/tlbflush.h>
  24
  25 #define KMAPAREA(x)     ((x >= VMALLOC_START) && (x < KMAP_END))
  26
  27 mm_context_t next_mmu_context;
  28 unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
  29 atomic_t nr_free_contexts;
  30 struct mm_struct *context_mm[LAST_CONTEXT+1];
  31 unsigned long num_pages;
  32
  33 /*
  34  * ColdFire paging_init derived from sun3.
  35  */
  36 void __init paging_init(void)
  37 {
  38         pgd_t *pg_dir;
  39         pte_t *pg_table;
  40         unsigned long address, size;
  41         unsigned long next_pgtable, bootmem_end;
  42         unsigned long zones_size[MAX_NR_ZONES];
  43         enum zone_type zone;
  44         int i;
  45
  46         empty_zero_page = (void *) alloc_bootmem_pages(PAGE_SIZE);
  47         memset((void *) empty_zero_page, 0, PAGE_SIZE);
  48
  49         pg_dir = swapper_pg_dir;
  50         memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
  51
  52         size = num_pages * sizeof(pte_t);
  53         size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
  54         next_pgtable = (unsigned long) alloc_bootmem_pages(size);
  55
  56         bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
  57         pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
  58
  59         address = PAGE_OFFSET;
  60         while (address < (unsigned long)high_memory) {
  61                 pg_table = (pte_t *) next_pgtable;
  62                 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
  63                 pgd_val(*pg_dir) = (unsigned long) pg_table;
  64                 pg_dir++;
  65
  66                 /* now change pg_table to kernel virtual addresses */
  67                 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
  68                         pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
  69                         if (address >= (unsigned long) high_memory)
  70                                 pte_val(pte) = 0;
  71
  72                         set_pte(pg_table, pte);
  73                         address += PAGE_SIZE;
  74                 }
  75         }
  76
  77         current->mm = NULL;
  78
  79         for (zone = 0; zone < MAX_NR_ZONES; zone++)
  80                 zones_size[zone] = 0x0;
  81         zones_size[ZONE_DMA] = num_pages;
  82         free_area_init(zones_size);
  83 }
  84
  85 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
  86 {
  87         unsigned long flags, mmuar, mmutr;
  88         struct mm_struct *mm;
  89         pgd_t *pgd;
  90         pmd_t *pmd;
  91         pte_t *pte;
  92         int asid;
  93
  94         local_irq_save(flags);
  95
  96         mmuar = (dtlb) ? mmu_read(MMUAR) :
  97                 regs->pc + (extension_word * sizeof(long));
  98
  99         mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
 100         if (!mm) {
 101                 local_irq_restore(flags);
 102                 return -1;
 103         }
 104
 105         pgd = pgd_offset(mm, mmuar);
 106         if (pgd_none(*pgd))  {
 107                 local_irq_restore(flags);
 108                 return -1;
 109         }
 110
 111         pmd = pmd_offset(pgd, mmuar);
 112         if (pmd_none(*pmd)) {
 113                 local_irq_restore(flags);
 114                 return -1;
 115         }
 116
 117         pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
 118                                 : pte_offset_map(pmd, mmuar);
 119         if (pte_none(*pte) || !pte_present(*pte)) {
 120                 local_irq_restore(flags);
 121                 return -1;
 122         }
 123
 124         if (write) {
 125                 if (!pte_write(*pte)) {
 126                         local_irq_restore(flags);
 127                         return -1;
 128                 }
 129                 set_pte(pte, pte_mkdirty(*pte));
 130         }
 131
 132         set_pte(pte, pte_mkyoung(*pte));
 133         asid = mm->context & 0xff;
 134         if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
 135                 set_pte(pte, pte_wrprotect(*pte));
 136
 137         mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
 138         if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
 139                 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
 140         mmu_write(MMUTR, mmutr);
 141
 142         mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
 143                 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
 144
 145         if (dtlb)
 146                 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
 147         else
 148                 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
 149
 150         local_irq_restore(flags);
 151         return 0;
 152 }
 153
 154 void __init cf_bootmem_alloc(void)
 155 {
 156         unsigned long start_pfn;
 157         unsigned long memstart;
 158
 159         /* _rambase and _ramend will be naturally page aligned */
 160         m68k_memory[0].addr = _rambase;
 161         m68k_memory[0].size = _ramend - _rambase;
 162
 163         /* compute total pages in system */
 164         num_pages = PFN_DOWN(_ramend - _rambase);
 165
 166         /* page numbers */
 167         memstart = PAGE_ALIGN(_ramstart);
 168         min_low_pfn = PFN_DOWN(_rambase);
 169         start_pfn = PFN_DOWN(memstart);
 170         max_pfn = max_low_pfn = PFN_DOWN(_ramend);
 171         high_memory = (void *)_ramend;
 172
 173         m68k_virt_to_node_shift = fls(_ramend - _rambase - 1) - 6;
 174         module_fixup(NULL, __start_fixup, __stop_fixup);
 175
 176         /* setup bootmem data */
 177         m68k_setup_node(0);
 178         memstart += init_bootmem_node(NODE_DATA(0), start_pfn,
 179                 min_low_pfn, max_low_pfn);
 180         free_bootmem_node(NODE_DATA(0), memstart, _ramend - memstart);
 181 }
 182
 183 /*
 184  * Initialize the context management stuff.
 185  * The following was taken from arch/ppc/mmu_context.c
 186  */
 187 void __init mmu_context_init(void)
 188 {
 189         /*
 190          * Some processors have too few contexts to reserve one for
 191          * init_mm, and require using context 0 for a normal task.
 192          * Other processors reserve the use of context zero for the kernel.
 193          * This code assumes FIRST_CONTEXT < 32.
 194          */
 195         context_map[0] = (1 << FIRST_CONTEXT) - 1;
 196         next_mmu_context = FIRST_CONTEXT;
 197         atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
 198 }
 199
 200 /*
 201  * Steal a context from a task that has one at the moment.
 202  * This is only used on 8xx and 4xx and we presently assume that
 203  * they don't do SMP.  If they do then thicfpgalloc.hs will have to check
 204  * whether the MM we steal is in use.
 205  * We also assume that this is only used on systems that don't
 206  * use an MMU hash table - this is true for 8xx and 4xx.
 207  * This isn't an LRU system, it just frees up each context in
 208  * turn (sort-of pseudo-random replacement :).  This would be the
 209  * place to implement an LRU scheme if anyone was motivated to do it.
 210  *  -- paulus
 211  */
 212 void steal_context(void)
 213 {
 214         struct mm_struct *mm;
 215         /*
 216          * free up context `next_mmu_context'
 217          * if we shouldn't free context 0, don't...
 218          */
 219         if (next_mmu_context < FIRST_CONTEXT)
 220                 next_mmu_context = FIRST_CONTEXT;
 221         mm = context_mm[next_mmu_context];
 222         flush_tlb_mm(mm);
 223         destroy_context(mm);
 224 }
 225