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/memblock.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 *) memblock_alloc(PAGE_SIZE, PAGE_SIZE);
  47         if (!empty_zero_page)
  48                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  49                       __func__, PAGE_SIZE, PAGE_SIZE);
  50
  51         pg_dir = swapper_pg_dir;
  52         memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
  53
  54         size = num_pages * sizeof(pte_t);
  55         size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
  56         next_pgtable = (unsigned long) memblock_alloc(size, PAGE_SIZE);
  57         if (!next_pgtable)
  58                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  59                       __func__, size, PAGE_SIZE);
  60
  61         bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
  62         pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
  63
  64         address = PAGE_OFFSET;
  65         while (address < (unsigned long)high_memory) {
  66                 pg_table = (pte_t *) next_pgtable;
  67                 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
  68                 pgd_val(*pg_dir) = (unsigned long) pg_table;
  69                 pg_dir++;
  70
  71                 /* now change pg_table to kernel virtual addresses */
  72                 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
  73                         pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
  74                         if (address >= (unsigned long) high_memory)
  75                                 pte_val(pte) = 0;
  76
  77                         set_pte(pg_table, pte);
  78                         address += PAGE_SIZE;
  79                 }
  80         }
  81
  82         current->mm = NULL;
  83
  84         for (zone = 0; zone < MAX_NR_ZONES; zone++)
  85                 zones_size[zone] = 0x0;
  86         zones_size[ZONE_DMA] = num_pages;
  87         free_area_init(zones_size);
  88 }
  89
  90 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
  91 {
  92         unsigned long flags, mmuar, mmutr;
  93         struct mm_struct *mm;
  94         pgd_t *pgd;
  95         pmd_t *pmd;
  96         pte_t *pte;
  97         int asid;
  98
  99         local_irq_save(flags);
 100
 101         mmuar = (dtlb) ? mmu_read(MMUAR) :
 102                 regs->pc + (extension_word * sizeof(long));
 103
 104         mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
 105         if (!mm) {
 106                 local_irq_restore(flags);
 107                 return -1;
 108         }
 109
 110         pgd = pgd_offset(mm, mmuar);
 111         if (pgd_none(*pgd))  {
 112                 local_irq_restore(flags);
 113                 return -1;
 114         }
 115
 116         pmd = pmd_offset(pgd, mmuar);
 117         if (pmd_none(*pmd)) {
 118                 local_irq_restore(flags);
 119                 return -1;
 120         }
 121
 122         pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
 123                                 : pte_offset_map(pmd, mmuar);
 124         if (pte_none(*pte) || !pte_present(*pte)) {
 125                 local_irq_restore(flags);
 126                 return -1;
 127         }
 128
 129         if (write) {
 130                 if (!pte_write(*pte)) {
 131                         local_irq_restore(flags);
 132                         return -1;
 133                 }
 134                 set_pte(pte, pte_mkdirty(*pte));
 135         }
 136
 137         set_pte(pte, pte_mkyoung(*pte));
 138         asid = mm->context & 0xff;
 139         if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
 140                 set_pte(pte, pte_wrprotect(*pte));
 141
 142         mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
 143         if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
 144                 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
 145         mmu_write(MMUTR, mmutr);
 146
 147         mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
 148                 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
 149
 150         if (dtlb)
 151                 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
 152         else
 153                 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
 154
 155         local_irq_restore(flags);
 156         return 0;
 157 }
 158
 159 void __init cf_bootmem_alloc(void)
 160 {
 161         unsigned long memstart;
 162
 163         /* _rambase and _ramend will be naturally page aligned */
 164         m68k_memory[0].addr = _rambase;
 165         m68k_memory[0].size = _ramend - _rambase;
 166
 167         memblock_add(m68k_memory[0].addr, m68k_memory[0].size);
 168
 169         /* compute total pages in system */
 170         num_pages = PFN_DOWN(_ramend - _rambase);
 171
 172         /* page numbers */
 173         memstart = PAGE_ALIGN(_ramstart);
 174         min_low_pfn = PFN_DOWN(_rambase);
 175         max_pfn = max_low_pfn = PFN_DOWN(_ramend);
 176         high_memory = (void *)_ramend;
 177
 178         /* Reserve kernel text/data/bss */
 179         memblock_reserve(_rambase, memstart - _rambase);
 180
 181         m68k_virt_to_node_shift = fls(_ramend - 1) - 6;
 182         module_fixup(NULL, __start_fixup, __stop_fixup);
 183
 184         /* setup node data */
 185         m68k_setup_node(0);
 186 }
 187
 188 /*
 189  * Initialize the context management stuff.
 190  * The following was taken from arch/ppc/mmu_context.c
 191  */
 192 void __init cf_mmu_context_init(void)
 193 {
 194         /*
 195          * Some processors have too few contexts to reserve one for
 196          * init_mm, and require using context 0 for a normal task.
 197          * Other processors reserve the use of context zero for the kernel.
 198          * This code assumes FIRST_CONTEXT < 32.
 199          */
 200         context_map[0] = (1 << FIRST_CONTEXT) - 1;
 201         next_mmu_context = FIRST_CONTEXT;
 202         atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
 203 }
 204
 205 /*
 206  * Steal a context from a task that has one at the moment.
 207  * This is only used on 8xx and 4xx and we presently assume that
 208  * they don't do SMP.  If they do then thicfpgalloc.hs will have to check
 209  * whether the MM we steal is in use.
 210  * We also assume that this is only used on systems that don't
 211  * use an MMU hash table - this is true for 8xx and 4xx.
 212  * This isn't an LRU system, it just frees up each context in
 213  * turn (sort-of pseudo-random replacement :).  This would be the
 214  * place to implement an LRU scheme if anyone was motivated to do it.
 215  *  -- paulus
 216  */
 217 void steal_context(void)
 218 {
 219         struct mm_struct *mm;
 220         /*
 221          * free up context `next_mmu_context'
 222          * if we shouldn't free context 0, don't...
 223          */
 224         if (next_mmu_context < FIRST_CONTEXT)
 225                 next_mmu_context = FIRST_CONTEXT;
 226         mm = context_mm[next_mmu_context];
 227         flush_tlb_mm(mm);
 228         destroy_context(mm);
 229 }
 230