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 p4d_t *p4d; 96 pud_t *pud; 97 pmd_t *pmd; 98 pte_t *pte; 99 int asid; 100 101 local_irq_save(flags); 102 103 mmuar = (dtlb) ? mmu_read(MMUAR) : 104 regs->pc + (extension_word * sizeof(long)); 105 106 mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm; 107 if (!mm) { 108 local_irq_restore(flags); 109 return -1; 110 } 111 112 pgd = pgd_offset(mm, mmuar); 113 if (pgd_none(*pgd)) { 114 local_irq_restore(flags); 115 return -1; 116 } 117 118 p4d = p4d_offset(pgd, mmuar); 119 if (p4d_none(*p4d)) { 120 local_irq_restore(flags); 121 return -1; 122 } 123 124 pud = pud_offset(p4d, mmuar); 125 if (pud_none(*pud)) { 126 local_irq_restore(flags); 127 return -1; 128 } 129 130 pmd = pmd_offset(pud, mmuar); 131 if (pmd_none(*pmd)) { 132 local_irq_restore(flags); 133 return -1; 134 } 135 136 pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar) 137 : pte_offset_map(pmd, mmuar); 138 if (pte_none(*pte) || !pte_present(*pte)) { 139 local_irq_restore(flags); 140 return -1; 141 } 142 143 if (write) { 144 if (!pte_write(*pte)) { 145 local_irq_restore(flags); 146 return -1; 147 } 148 set_pte(pte, pte_mkdirty(*pte)); 149 } 150 151 set_pte(pte, pte_mkyoung(*pte)); 152 asid = mm->context & 0xff; 153 if (!pte_dirty(*pte) && !KMAPAREA(mmuar)) 154 set_pte(pte, pte_wrprotect(*pte)); 155 156 mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V; 157 if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE)) 158 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT; 159 mmu_write(MMUTR, mmutr); 160 161 mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) | 162 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X); 163 164 if (dtlb) 165 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA); 166 else 167 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA); 168 169 local_irq_restore(flags); 170 return 0; 171 } 172 173 void __init cf_bootmem_alloc(void) 174 { 175 unsigned long memstart; 176 177 /* _rambase and _ramend will be naturally page aligned */ 178 m68k_memory[0].addr = _rambase; 179 m68k_memory[0].size = _ramend - _rambase; 180 181 memblock_add(m68k_memory[0].addr, m68k_memory[0].size); 182 183 /* compute total pages in system */ 184 num_pages = PFN_DOWN(_ramend - _rambase); 185 186 /* page numbers */ 187 memstart = PAGE_ALIGN(_ramstart); 188 min_low_pfn = PFN_DOWN(_rambase); 189 max_pfn = max_low_pfn = PFN_DOWN(_ramend); 190 high_memory = (void *)_ramend; 191 192 /* Reserve kernel text/data/bss */ 193 memblock_reserve(_rambase, memstart - _rambase); 194 195 m68k_virt_to_node_shift = fls(_ramend - 1) - 6; 196 module_fixup(NULL, __start_fixup, __stop_fixup); 197 198 /* setup node data */ 199 m68k_setup_node(0); 200 } 201 202 /* 203 * Initialize the context management stuff. 204 * The following was taken from arch/ppc/mmu_context.c 205 */ 206 void __init cf_mmu_context_init(void) 207 { 208 /* 209 * Some processors have too few contexts to reserve one for 210 * init_mm, and require using context 0 for a normal task. 211 * Other processors reserve the use of context zero for the kernel. 212 * This code assumes FIRST_CONTEXT < 32. 213 */ 214 context_map[0] = (1 << FIRST_CONTEXT) - 1; 215 next_mmu_context = FIRST_CONTEXT; 216 atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1); 217 } 218 219 /* 220 * Steal a context from a task that has one at the moment. 221 * This is only used on 8xx and 4xx and we presently assume that 222 * they don't do SMP. If they do then thicfpgalloc.hs will have to check 223 * whether the MM we steal is in use. 224 * We also assume that this is only used on systems that don't 225 * use an MMU hash table - this is true for 8xx and 4xx. 226 * This isn't an LRU system, it just frees up each context in 227 * turn (sort-of pseudo-random replacement :). This would be the 228 * place to implement an LRU scheme if anyone was motivated to do it. 229 * -- paulus 230 */ 231 void steal_context(void) 232 { 233 struct mm_struct *mm; 234 /* 235 * free up context `next_mmu_context' 236 * if we shouldn't free context 0, don't... 237 */ 238 if (next_mmu_context < FIRST_CONTEXT) 239 next_mmu_context = FIRST_CONTEXT; 240 mm = context_mm[next_mmu_context]; 241 flush_tlb_mm(mm); 242 destroy_context(mm); 243 } 244 245