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
27mm_context_t next_mmu_context;
28unsigned long context_map[LAST_CONTEXT / BITS_PER_LONG + 1];
29atomic_t nr_free_contexts;
30struct mm_struct *context_mm[LAST_CONTEXT+1];
31unsigned long num_pages;
32
33/*
34 * ColdFire paging_init derived from sun3.
35 */
36void __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;
42 unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
43 int i;
44
45 empty_zero_page = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
46
47 pg_dir = swapper_pg_dir;
48 memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
49
50 size = num_pages * sizeof(pte_t);
51 size = (size + PAGE_SIZE) & ~(PAGE_SIZE-1);
52 next_pgtable = (unsigned long) memblock_alloc_or_panic(size, PAGE_SIZE);
53
54 pg_dir += PAGE_OFFSET >> PGDIR_SHIFT;
55
56 address = PAGE_OFFSET;
57 while (address < (unsigned long)high_memory) {
58 pg_table = (pte_t *) next_pgtable;
59 next_pgtable += PTRS_PER_PTE * sizeof(pte_t);
60 pgd_val(pgd: *pg_dir) = (unsigned long) pg_table;
61 pg_dir++;
62
63 /* now change pg_table to kernel virtual addresses */
64 for (i = 0; i < PTRS_PER_PTE; ++i, ++pg_table) {
65 pte_t pte = pfn_pte(page_nr: virt_to_pfn((void *)address),
66 pgprot: PAGE_INIT);
67 if (address >= (unsigned long) high_memory)
68 pte_val(pte) = 0;
69
70 set_pte(ptep: pg_table, pte);
71 address += PAGE_SIZE;
72 }
73 }
74
75 current->mm = NULL;
76 max_zone_pfn[ZONE_DMA] = PFN_DOWN(_ramend);
77 free_area_init(max_zone_pfn);
78}
79
80int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
81{
82 unsigned long flags, mmuar, mmutr;
83 struct mm_struct *mm;
84 pgd_t *pgd;
85 p4d_t *p4d;
86 pud_t *pud;
87 pmd_t *pmd;
88 pte_t *pte = NULL;
89 int ret = -1;
90 int asid;
91
92 local_irq_save(flags);
93
94 mmuar = (dtlb) ? mmu_read(MMUAR) :
95 regs->pc + (extension_word * sizeof(long));
96
97 mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
98 if (!mm)
99 goto out;
100
101 pgd = pgd_offset(mm, mmuar);
102 if (pgd_none(pgd: *pgd))
103 goto out;
104
105 p4d = p4d_offset(pgd, address: mmuar);
106 if (p4d_none(p4d: *p4d))
107 goto out;
108
109 pud = pud_offset(p4d, address: mmuar);
110 if (pud_none(pud: *pud))
111 goto out;
112
113 pmd = pmd_offset(pud, address: mmuar);
114 if (pmd_none(pmd: *pmd))
115 goto out;
116
117 pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
118 : pte_offset_map(pmd, mmuar);
119 if (!pte || pte_none(pte: *pte) || !pte_present(a: *pte))
120 goto out;
121
122 if (write) {
123 if (!pte_write(pte: *pte))
124 goto out;
125 set_pte(ptep: pte, pte: pte_mkdirty(pte: *pte));
126 }
127
128 set_pte(ptep: pte, pte: pte_mkyoung(pte: *pte));
129 asid = mm->context & 0xff;
130 if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
131 set_pte(ptep: pte, pte: pte_wrprotect(pte: *pte));
132
133 mmutr = (mmuar & PAGE_MASK) | (asid << MMUTR_IDN) | MMUTR_V;
134 if ((mmuar < TASK_UNMAPPED_BASE) || (mmuar >= TASK_SIZE))
135 mmutr |= (pte->pte & CF_PAGE_MMUTR_MASK) >> CF_PAGE_MMUTR_SHIFT;
136 mmu_write(MMUTR, mmutr);
137
138 mmu_write(MMUDR, (pte_val(*pte) & PAGE_MASK) |
139 ((pte->pte) & CF_PAGE_MMUDR_MASK) | MMUDR_SZ_8KB | MMUDR_X);
140
141 if (dtlb)
142 mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
143 else
144 mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
145 ret = 0;
146out:
147 if (pte && !KMAPAREA(mmuar))
148 pte_unmap(pte);
149 local_irq_restore(flags);
150 return ret;
151}
152
153void __init cf_bootmem_alloc(void)
154{
155 unsigned long memstart;
156
157 /* _rambase and _ramend will be naturally page aligned */
158 m68k_memory[0].addr = _rambase;
159 m68k_memory[0].size = _ramend - _rambase;
160
161 memblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0,
162 MEMBLOCK_NONE);
163
164 /* compute total pages in system */
165 num_pages = PFN_DOWN(_ramend - _rambase);
166
167 /* page numbers */
168 memstart = PAGE_ALIGN(_ramstart);
169 min_low_pfn = PFN_DOWN(_rambase);
170 max_pfn = max_low_pfn = PFN_DOWN(_ramend);
171 high_memory = (void *)_ramend;
172
173 /* Reserve kernel text/data/bss */
174 memblock_reserve(_rambase, memstart - _rambase);
175
176 m68k_virt_to_node_shift = fls(_ramend - 1) - 6;
177 module_fixup(NULL, __start_fixup, __stop_fixup);
178
179 /* setup node data */
180 m68k_setup_node(0);
181}
182
183/*
184 * Initialize the context management stuff.
185 * The following was taken from arch/ppc/mmu_context.c
186 */
187void __init cf_mmu_context_init(void)
188{
189 /*
190 * Some processors have too few contexts to reserve one for
191 * init_mm, and require using context 0 for a normal task.
192 * Other processors reserve the use of context zero for the kernel.
193 * This code assumes FIRST_CONTEXT < 32.
194 */
195 context_map[0] = (1 << FIRST_CONTEXT) - 1;
196 next_mmu_context = FIRST_CONTEXT;
197 atomic_set(&nr_free_contexts, LAST_CONTEXT - FIRST_CONTEXT + 1);
198}
199
200/*
201 * Steal a context from a task that has one at the moment.
202 * This isn't an LRU system, it just frees up each context in
203 * turn (sort-of pseudo-random replacement :). This would be the
204 * place to implement an LRU scheme if anyone was motivated to do it.
205 * -- paulus
206 */
207void steal_context(void)
208{
209 struct mm_struct *mm;
210 /*
211 * free up context `next_mmu_context'
212 * if we shouldn't free context 0, don't...
213 */
214 if (next_mmu_context < FIRST_CONTEXT)
215 next_mmu_context = FIRST_CONTEXT;
216 mm = context_mm[next_mmu_context];
217 flush_tlb_mm(mm);
218 destroy_context(mm);
219}
220
221static const pgprot_t protection_map[16] = {
222 [VM_NONE] = PAGE_NONE,
223 [VM_READ] = __pgprot(CF_PAGE_VALID |
224 CF_PAGE_ACCESSED |
225 CF_PAGE_READABLE),
226 [VM_WRITE] = __pgprot(CF_PAGE_VALID |
227 CF_PAGE_ACCESSED |
228 CF_PAGE_WRITABLE),
229 [VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
230 CF_PAGE_ACCESSED |
231 CF_PAGE_READABLE |
232 CF_PAGE_WRITABLE),
233 [VM_EXEC] = __pgprot(CF_PAGE_VALID |
234 CF_PAGE_ACCESSED |
235 CF_PAGE_EXEC),
236 [VM_EXEC | VM_READ] = __pgprot(CF_PAGE_VALID |
237 CF_PAGE_ACCESSED |
238 CF_PAGE_READABLE |
239 CF_PAGE_EXEC),
240 [VM_EXEC | VM_WRITE] = __pgprot(CF_PAGE_VALID |
241 CF_PAGE_ACCESSED |
242 CF_PAGE_WRITABLE |
243 CF_PAGE_EXEC),
244 [VM_EXEC | VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
245 CF_PAGE_ACCESSED |
246 CF_PAGE_READABLE |
247 CF_PAGE_WRITABLE |
248 CF_PAGE_EXEC),
249 [VM_SHARED] = PAGE_NONE,
250 [VM_SHARED | VM_READ] = __pgprot(CF_PAGE_VALID |
251 CF_PAGE_ACCESSED |
252 CF_PAGE_READABLE),
253 [VM_SHARED | VM_WRITE] = PAGE_SHARED,
254 [VM_SHARED | VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
255 CF_PAGE_ACCESSED |
256 CF_PAGE_READABLE |
257 CF_PAGE_SHARED),
258 [VM_SHARED | VM_EXEC] = __pgprot(CF_PAGE_VALID |
259 CF_PAGE_ACCESSED |
260 CF_PAGE_EXEC),
261 [VM_SHARED | VM_EXEC | VM_READ] = __pgprot(CF_PAGE_VALID |
262 CF_PAGE_ACCESSED |
263 CF_PAGE_READABLE |
264 CF_PAGE_EXEC),
265 [VM_SHARED | VM_EXEC | VM_WRITE] = __pgprot(CF_PAGE_VALID |
266 CF_PAGE_ACCESSED |
267 CF_PAGE_SHARED |
268 CF_PAGE_EXEC),
269 [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = __pgprot(CF_PAGE_VALID |
270 CF_PAGE_ACCESSED |
271 CF_PAGE_READABLE |
272 CF_PAGE_SHARED |
273 CF_PAGE_EXEC)
274};
275DECLARE_VM_GET_PAGE_PROT
276

source code of linux/arch/m68k/mm/mcfmmu.c