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 } 195 196