mcfmmu.c

  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(*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(virt_to_pfn((void *)address),
 66					    PAGE_INIT);
 67			if (address >= (unsigned long) high_memory)
 68				pte_val(pte) = 0;
 69
 70			set_pte(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))
103		goto out;
104
105	p4d = p4d_offset(pgd, mmuar);
106	if (p4d_none(*p4d))
107		goto out;
108
109	pud = pud_offset(p4d, mmuar);
110	if (pud_none(*pud))
111		goto out;
112
113	pmd = pmd_offset(pud, mmuar);
114	if (pmd_none(*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_present(*pte))
120		goto out;
121
122	if (write) {
123		if (!pte_write(*pte))
124			goto out;
125		set_pte(pte, pte_mkdirty(*pte));
126	}
127
128	set_pte(pte, pte_mkyoung(*pte));
129	asid = mm->context & 0xff;
130	if (!pte_dirty(*pte) && !KMAPAREA(mmuar))
131		set_pte(pte, pte_wrprotect(*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