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 MEMBLOCK_NONE); 179 180 /* compute total pages in system */ 181 num_pages = PFN_DOWN(_ramend - _rambase); 182 183 /* page numbers */ 184 memstart = PAGE_ALIGN(_ramstart); 185 min_low_pfn = PFN_DOWN(_rambase); 186 max_pfn = max_low_pfn = PFN_DOWN(_ramend); 187 high_memory = (void *)_ramend; 188 189 /* Reserve kernel text/data/bss */ 190 memblock_reserve(_rambase, memstart - _rambase); 191 192 m68k_virt_to_node_shift = fls(_ramend - 1) - 6; 193 module_fixup(NULL, __start_fixup, __stop_fixup); 194 195 /* setup node data */ 196 m68k_setup_node(0); 197 } 198 199 /* 200 * Initialize the context management stuff. 201 * The following was taken from arch/ppc/mmu_context.c 202 */ 203 void __init cf_mmu_context_init(void) 204 { 205 /* 206 * Some processors have too few contexts to reserve one for 207 * init_mm, and require using context 0 for a normal task. 208 * Other processors reserve the use of context zero for the kernel. 209 * This code assumes FIRST_CONTEXT < 32. 210 */ 211 context_map[0] = (1 << FIRST_CONTEXT) - 1; 212 next_mmu_context = FIRST_CONTEXT; 213 atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1); 214 } 215 216 /* 217 * Steal a context from a task that has one at the moment. 218 * This isn't an LRU system, it just frees up each context in 219 * turn (sort-of pseudo-random replacement :). This would be the 220 * place to implement an LRU scheme if anyone was motivated to do it. 221 * -- paulus 222 */ 223 void steal_context(void) 224 { 225 struct mm_struct *mm; 226 /* 227 * free up context `next_mmu_context' 228 * if we shouldn't free context 0, don't... 229 */ 230 if (next_mmu_context < FIRST_CONTEXT) 231 next_mmu_context = FIRST_CONTEXT; 232 mm = context_mm[next_mmu_context]; 233 flush_tlb_mm(mm); 234 destroy_context(mm); 235 } 236 237