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