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 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 void __init cf_bootmem_alloc(void) 154 { 155 unsigned long start_pfn; 156 unsigned long memstart; 157 158 /* _rambase and _ramend will be naturally page aligned */ 159 m68k_memory[0].addr = _rambase; 160 m68k_memory[0].size = _ramend - _rambase; 161 162 /* compute total pages in system */ 163 num_pages = PFN_DOWN(_ramend - _rambase); 164 165 /* page numbers */ 166 memstart = PAGE_ALIGN(_ramstart); 167 min_low_pfn = PFN_DOWN(_rambase); 168 start_pfn = PFN_DOWN(memstart); 169 max_pfn = max_low_pfn = PFN_DOWN(_ramend); 170 high_memory = (void *)_ramend; 171 172 m68k_virt_to_node_shift = fls(_ramend - _rambase - 1) - 6; 173 module_fixup(NULL, __start_fixup, __stop_fixup); 174 175 /* setup bootmem data */ 176 m68k_setup_node(0); 177 memstart += init_bootmem_node(NODE_DATA(0), start_pfn, 178 min_low_pfn, max_low_pfn); 179 free_bootmem_node(NODE_DATA(0), memstart, _ramend - memstart); 180 } 181 182 /* 183 * Initialize the context management stuff. 184 * The following was taken from arch/ppc/mmu_context.c 185 */ 186 void __init mmu_context_init(void) 187 { 188 /* 189 * Some processors have too few contexts to reserve one for 190 * init_mm, and require using context 0 for a normal task. 191 * Other processors reserve the use of context zero for the kernel. 192 * This code assumes FIRST_CONTEXT < 32. 193 */ 194 context_map[0] = (1 << FIRST_CONTEXT) - 1; 195 next_mmu_context = FIRST_CONTEXT; 196 atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1); 197 } 198 199 /* 200 * Steal a context from a task that has one at the moment. 201 * This is only used on 8xx and 4xx and we presently assume that 202 * they don't do SMP. If they do then thicfpgalloc.hs will have to check 203 * whether the MM we steal is in use. 204 * We also assume that this is only used on systems that don't 205 * use an MMU hash table - this is true for 8xx and 4xx. 206 * This isn't an LRU system, it just frees up each context in 207 * turn (sort-of pseudo-random replacement :). This would be the 208 * place to implement an LRU scheme if anyone was motivated to do it. 209 * -- paulus 210 */ 211 void steal_context(void) 212 { 213 struct mm_struct *mm; 214 /* 215 * free up context `next_mmu_context' 216 * if we shouldn't free context 0, don't... 217 */ 218 if (next_mmu_context < FIRST_CONTEXT) 219 next_mmu_context = FIRST_CONTEXT; 220 mm = context_mm[next_mmu_context]; 221 flush_tlb_mm(mm); 222 destroy_context(mm); 223 } 224 225