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/mmu_context.h>
  21 #include <asm/mcf_pgalloc.h>
  22 #include <asm/tlbflush.h>
  23 #include <asm/pgalloc.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 max_zone_pfn[MAX_NR_ZONES] = { 0 };
  43         int i;
  44
  45         empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
  46         if (!empty_zero_page)
  47                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  48                       __func__, PAGE_SIZE, PAGE_SIZE);
  49
  50         pg_dir = swapper_pg_dir;
  51         memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
  52
  53         size = num_pages * sizeof(pte_t);
  54         size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
  55         next_pgtable = (unsigned long) memblock_alloc(size, PAGE_SIZE);
  56         if (!next_pgtable)
  57                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  58                       __func__, size, PAGE_SIZE);
  59
  60         bootmem_end = (next_pgtable + size + PAGE_SIZE) & PAGE_MASK;
  61         pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
  62
  63         address = PAGE_OFFSET;
  64         while (address < (unsigned long)high_memory) {
  65                 pg_table = (pte_t *) next_pgtable;
  66                 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
  67                 pgd_val(*pg_dir) = (unsigned long) pg_table;
  68                 pg_dir++;
  69
  70                 /* now change pg_table to kernel virtual addresses */
  71                 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
  72                         pte_t pte = pfn_pte(virt_to_pfn(address), PAGE_INIT);
  73                         if (address >= (unsigned long) high_memory)
  74                                 pte_val(pte) = 0;
  75
  76                         set_pte(pg_table, pte);
  77                         address += PAGE_SIZE;
  78                 }
  79         }
  80
  81         current->mm = NULL;
  82         max_zone_pfn[ZONE_DMA] = PFN_DOWN(_ramend);
  83         free_area_init(max_zone_pfn);
  84 }
  85
  86 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
  87 {
  88         unsigned long flags, mmuar, mmutr;
  89         struct mm_struct *mm;
  90         pgd_t *pgd;
  91         p4d_t *p4d;
  92         pud_t *pud;
  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         p4d = p4d_offset(pgd, mmuar);
 115         if (p4d_none(*p4d)) {
 116                 local_irq_restore(flags);
 117                 return -1;
 118         }
 119
 120         pud = pud_offset(p4d, mmuar);
 121         if (pud_none(*pud)) {
 122                 local_irq_restore(flags);
 123                 return -1;
 124         }
 125
 126         pmd = pmd_offset(pud, mmuar);
 127         if (pmd_none(*pmd)) {
 128                 local_irq_restore(flags);
 129                 return -1;
 130         }
 131
 132         pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
 133                                 : pte_offset_map(pmd, mmuar);
 134         if (pte_none(*pte) || !pte_present(*pte)) {
 135                 local_irq_restore(flags);
 136                 return -1;
 137         }
 138
 139         if (write) {
 140                 if (!pte_write(*pte)) {
 141                         local_irq_restore(flags);
 142                         return -1;
 143                 }
 144                 set_pte(pte, pte_mkdirty(*pte));
 145         }
 146
 147         set_pte(pte, pte_mkyoung(*pte));
 148         asid = mm->context & 0xff;
 149         if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
 150                 set_pte(pte, pte_wrprotect(*pte));
 151
 152         mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
 153         if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
 154                 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
 155         mmu_write(MMUTR, mmutr);
 156
 157         mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
 158                 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
 159
 160         if (dtlb)
 161                 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
 162         else
 163                 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
 164
 165         local_irq_restore(flags);
 166         return 0;
 167 }
 168
 169 void __init cf_bootmem_alloc(void)
 170 {
 171         unsigned long memstart;
 172
 173         /* _rambase and _ramend will be naturally page aligned */
 174         m68k_memory[0].addr = _rambase;
 175         m68k_memory[0].size = _ramend - _rambase;
 176
 177         memblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0);
 178
 179         /* compute total pages in system */
 180         num_pages = PFN_DOWN(_ramend - _rambase);
 181
 182         /* page numbers */
 183         memstart = PAGE_ALIGN(_ramstart);
 184         min_low_pfn = PFN_DOWN(_rambase);
 185         max_pfn = max_low_pfn = PFN_DOWN(_ramend);
 186         high_memory = (void *)_ramend;
 187
 188         /* Reserve kernel text/data/bss */
 189         memblock_reserve(_rambase, memstart - _rambase);
 190
 191         m68k_virt_to_node_shift = fls(_ramend - 1) - 6;
 192         module_fixup(NULL, __start_fixup, __stop_fixup);
 193
 194         /* setup node data */
 195         m68k_setup_node(0);
 196 }
 197
 198 /*
 199  * Initialize the context management stuff.
 200  * The following was taken from arch/ppc/mmu_context.c
 201  */
 202 void __init cf_mmu_context_init(void)
 203 {
 204         /*
 205          * Some processors have too few contexts to reserve one for
 206          * init_mm, and require using context 0 for a normal task.
 207          * Other processors reserve the use of context zero for the kernel.
 208          * This code assumes FIRST_CONTEXT < 32.
 209          */
 210         context_map[0] = (1 << FIRST_CONTEXT) - 1;
 211         next_mmu_context = FIRST_CONTEXT;
 212         atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
 213 }
 214
 215 /*
 216  * Steal a context from a task that has one at the moment.
 217  * This isn't an LRU system, it just frees up each context in
 218  * turn (sort-of pseudo-random replacement :).  This would be the
 219  * place to implement an LRU scheme if anyone was motivated to do it.
 220  *  -- paulus
 221  */
 222 void steal_context(void)
 223 {
 224         struct mm_struct *mm;
 225         /*
 226          * free up context `next_mmu_context'
 227          * if we shouldn't free context 0, don't...
 228          */
 229         if (next_mmu_context < FIRST_CONTEXT)
 230                 next_mmu_context = FIRST_CONTEXT;
 231         mm = context_mm[next_mmu_context];
 232         flush_tlb_mm(mm);
 233         destroy_context(mm);
 234 }
 235