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(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 
cf_tlb_miss(struct pt_regs * regs,int write,int dtlb,int extension_word)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 
cf_bootmem_alloc(void)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  */
cf_mmu_context_init(void)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  */
steal_context(void)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