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 } 199 200