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 */
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 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((void *)address),
73 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 max_zone_pfn[ZONE_DMA] = PFN_DOWN(_ramend);
84 free_area_init(max_zone_pfn);
85 }
86
cf_tlb_miss(struct pt_regs * regs,int write,int dtlb,int extension_word)87 int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
88 {
89 unsigned long flags, mmuar, mmutr;
90 struct mm_struct *mm;
91 pgd_t *pgd;
92 p4d_t *p4d;
93 pud_t *pud;
94 pmd_t *pmd;
95 pte_t *pte = NULL;
96 int ret = -1;
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 goto out;
107
108 pgd = pgd_offset(mm, mmuar);
109 if (pgd_none(*pgd))
110 goto out;
111
112 p4d = p4d_offset(pgd, mmuar);
113 if (p4d_none(*p4d))
114 goto out;
115
116 pud = pud_offset(p4d, mmuar);
117 if (pud_none(*pud))
118 goto out;
119
120 pmd = pmd_offset(pud, mmuar);
121 if (pmd_none(*pmd))
122 goto out;
123
124 pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
125 : pte_offset_map(pmd, mmuar);
126 if (!pte || pte_none(*pte) || !pte_present(*pte))
127 goto out;
128
129 if (write) {
130 if (!pte_write(*pte))
131 goto out;
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 ret = 0;
153 out:
154 if (pte && !KMAPAREA(mmuar))
155 pte_unmap(pte);
156 local_irq_restore(flags);
157 return ret;
158 }
159
cf_bootmem_alloc(void)160 void __init cf_bootmem_alloc(void)
161 {
162 unsigned long memstart;
163
164 /* _rambase and _ramend will be naturally page aligned */
165 m68k_memory[0].addr = _rambase;
166 m68k_memory[0].size = _ramend - _rambase;
167
168 memblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0,
169 MEMBLOCK_NONE);
170
171 /* compute total pages in system */
172 num_pages = PFN_DOWN(_ramend - _rambase);
173
174 /* page numbers */
175 memstart = PAGE_ALIGN(_ramstart);
176 min_low_pfn = PFN_DOWN(_rambase);
177 max_pfn = max_low_pfn = PFN_DOWN(_ramend);
178 high_memory = (void *)_ramend;
179
180 /* Reserve kernel text/data/bss */
181 memblock_reserve(_rambase, memstart - _rambase);
182
183 m68k_virt_to_node_shift = fls(_ramend - 1) - 6;
184 module_fixup(NULL, __start_fixup, __stop_fixup);
185
186 /* setup node data */
187 m68k_setup_node(0);
188 }
189
190 /*
191 * Initialize the context management stuff.
192 * The following was taken from arch/ppc/mmu_context.c
193 */
cf_mmu_context_init(void)194 void __init cf_mmu_context_init(void)
195 {
196 /*
197 * Some processors have too few contexts to reserve one for
198 * init_mm, and require using context 0 for a normal task.
199 * Other processors reserve the use of context zero for the kernel.
200 * This code assumes FIRST_CONTEXT < 32.
201 */
202 context_map[0] = (1 << FIRST_CONTEXT) - 1;
203 next_mmu_context = FIRST_CONTEXT;
204 atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
205 }
206
207 /*
208 * Steal a context from a task that has one at the moment.
209 * This isn't an LRU system, it just frees up each context in
210 * turn (sort-of pseudo-random replacement :). This would be the
211 * place to implement an LRU scheme if anyone was motivated to do it.
212 * -- paulus
213 */
steal_context(void)214 void steal_context(void)
215 {
216 struct mm_struct *mm;
217 /*
218 * free up context `next_mmu_context'
219 * if we shouldn't free context 0, don't...
220 */
221 if (next_mmu_context < FIRST_CONTEXT)
222 next_mmu_context = FIRST_CONTEXT;
223 mm = context_mm[next_mmu_context];
224 flush_tlb_mm(mm);
225 destroy_context(mm);
226 }
227
228 static const pgprot_t protection_map[16] = {
229 [VM_NONE] = PAGE_NONE,
230 [VM_READ] = __pgprot(CF_PAGE_VALID |
231 CF_PAGE_ACCESSED |
232 CF_PAGE_READABLE),
233 [VM_WRITE] = __pgprot(CF_PAGE_VALID |
234 CF_PAGE_ACCESSED |
235 CF_PAGE_WRITABLE),
236 [VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
237 CF_PAGE_ACCESSED |
238 CF_PAGE_READABLE |
239 CF_PAGE_WRITABLE),
240 [VM_EXEC] = __pgprot(CF_PAGE_VALID |
241 CF_PAGE_ACCESSED |
242 CF_PAGE_EXEC),
243 [VM_EXEC | VM_READ] = __pgprot(CF_PAGE_VALID |
244 CF_PAGE_ACCESSED |
245 CF_PAGE_READABLE |
246 CF_PAGE_EXEC),
247 [VM_EXEC | VM_WRITE] = __pgprot(CF_PAGE_VALID |
248 CF_PAGE_ACCESSED |
249 CF_PAGE_WRITABLE |
250 CF_PAGE_EXEC),
251 [VM_EXEC | VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
252 CF_PAGE_ACCESSED |
253 CF_PAGE_READABLE |
254 CF_PAGE_WRITABLE |
255 CF_PAGE_EXEC),
256 [VM_SHARED] = PAGE_NONE,
257 [VM_SHARED | VM_READ] = __pgprot(CF_PAGE_VALID |
258 CF_PAGE_ACCESSED |
259 CF_PAGE_READABLE),
260 [VM_SHARED | VM_WRITE] = PAGE_SHARED,
261 [VM_SHARED | VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
262 CF_PAGE_ACCESSED |
263 CF_PAGE_READABLE |
264 CF_PAGE_SHARED),
265 [VM_SHARED | VM_EXEC] = __pgprot(CF_PAGE_VALID |
266 CF_PAGE_ACCESSED |
267 CF_PAGE_EXEC),
268 [VM_SHARED | VM_EXEC | VM_READ] = __pgprot(CF_PAGE_VALID |
269 CF_PAGE_ACCESSED |
270 CF_PAGE_READABLE |
271 CF_PAGE_EXEC),
272 [VM_SHARED | VM_EXEC | VM_WRITE] = __pgprot(CF_PAGE_VALID |
273 CF_PAGE_ACCESSED |
274 CF_PAGE_SHARED |
275 CF_PAGE_EXEC),
276 [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
277 CF_PAGE_ACCESSED |
278 CF_PAGE_READABLE |
279 CF_PAGE_SHARED |
280 CF_PAGE_EXEC)
281 };
282 DECLARE_VM_GET_PAGE_PROT
283
