aboutsummaryrefslogtreecommitdiff
path: root/arch/cris/arch-v10/mm/tlb.c
blob: 9d06125ff5a27fce36a4ab85ccd41fbb365089d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
/*
 *  linux/arch/cris/arch-v10/mm/tlb.c
 *
 *  Low level TLB handling
 *
 *
 *  Copyright (C) 2000-2002  Axis Communications AB
 *  
 *  Authors:   Bjorn Wesen (bjornw@axis.com)
 *
 */

#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/arch/svinto.h>

#define D(x)

/* The TLB can host up to 64 different mm contexts at the same time.
 * The running context is R_MMU_CONTEXT, and each TLB entry contains a
 * page_id that has to match to give a hit. In page_id_map, we keep track
 * of which mm's we have assigned which page_id's, so that we know when
 * to invalidate TLB entries.
 *
 * The last page_id is never running - it is used as an invalid page_id
 * so we can make TLB entries that will never match.
 *
 * Notice that we need to make the flushes atomic, otherwise an interrupt
 * handler that uses vmalloced memory might cause a TLB load in the middle
 * of a flush causing.
 */

/* invalidate all TLB entries */

void
flush_tlb_all(void)
{
	int i;
	unsigned long flags;

	/* the vpn of i & 0xf is so we dont write similar TLB entries
	 * in the same 4-way entry group. details.. 
	 */

	local_save_flags(flags);
	local_irq_disable();
	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
		*R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
		*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
			      IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
		
		*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no       ) |
			      IO_STATE(R_TLB_LO, valid, no       ) |
			      IO_STATE(R_TLB_LO, kernel,no	 ) |
			      IO_STATE(R_TLB_LO, we,    no       ) |
			      IO_FIELD(R_TLB_LO, pfn,   0        ) );
	}
	local_irq_restore(flags);
	D(printk("tlb: flushed all\n"));
}

/* invalidate the selected mm context only */

void
flush_tlb_mm(struct mm_struct *mm)
{
	int i;
	int page_id = mm->context.page_id;
	unsigned long flags;

	D(printk("tlb: flush mm context %d (%p)\n", page_id, mm));

	if(page_id == NO_CONTEXT)
		return;
	
	/* mark the TLB entries that match the page_id as invalid.
	 * here we could also check the _PAGE_GLOBAL bit and NOT flush
	 * global pages. is it worth the extra I/O ? 
	 */

	local_save_flags(flags);
	local_irq_disable();
	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
		*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
		if (IO_EXTRACT(R_TLB_HI, page_id, *R_TLB_HI) == page_id) {
			*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
				      IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
			
			*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
				      IO_STATE(R_TLB_LO, valid, no  ) |
				      IO_STATE(R_TLB_LO, kernel,no  ) |
				      IO_STATE(R_TLB_LO, we,    no  ) |
				      IO_FIELD(R_TLB_LO, pfn,   0   ) );
		}
	}
	local_irq_restore(flags);
}

/* invalidate a single page */

void
flush_tlb_page(struct vm_area_struct *vma, 
	       unsigned long addr)
{
	struct mm_struct *mm = vma->vm_mm;
	int page_id = mm->context.page_id;
	int i;
	unsigned long flags;

	D(printk("tlb: flush page %p in context %d (%p)\n", addr, page_id, mm));

	if(page_id == NO_CONTEXT)
		return;

	addr &= PAGE_MASK; /* perhaps not necessary */

	/* invalidate those TLB entries that match both the mm context
	 * and the virtual address requested 
	 */

	local_save_flags(flags);
	local_irq_disable();
	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
		unsigned long tlb_hi;
		*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
		tlb_hi = *R_TLB_HI;
		if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
		    (tlb_hi & PAGE_MASK) == addr) {
			*R_TLB_HI = IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
				addr; /* same addr as before works. */
			
			*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
				      IO_STATE(R_TLB_LO, valid, no  ) |
				      IO_STATE(R_TLB_LO, kernel,no  ) |
				      IO_STATE(R_TLB_LO, we,    no  ) |
				      IO_FIELD(R_TLB_LO, pfn,   0   ) );
		}
	}
	local_irq_restore(flags);
}

/* invalidate a page range */

void
flush_tlb_range(struct vm_area_struct *vma, 
		unsigned long start,
		unsigned long end)
{
	struct mm_struct *mm = vma->vm_mm;
	int page_id = mm->context.page_id;
	int i;
	unsigned long flags;

	D(printk("tlb: flush range %p<->%p in context %d (%p)\n",
		 start, end, page_id, mm));

	if(page_id == NO_CONTEXT)
		return;

	start &= PAGE_MASK;  /* probably not necessary */
	end &= PAGE_MASK;    /* dito */

	/* invalidate those TLB entries that match both the mm context
	 * and the virtual address range
	 */

	local_save_flags(flags);
	local_irq_disable();
	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
		unsigned long tlb_hi, vpn;
		*R_TLB_SELECT = IO_FIELD(R_TLB_SELECT, index, i);
		tlb_hi = *R_TLB_HI;
		vpn = tlb_hi & PAGE_MASK;
		if (IO_EXTRACT(R_TLB_HI, page_id, tlb_hi) == page_id &&
		    vpn >= start && vpn < end) {
			*R_TLB_HI = ( IO_FIELD(R_TLB_HI, page_id, INVALID_PAGEID ) |
				      IO_FIELD(R_TLB_HI, vpn,     i & 0xf ) );
			
			*R_TLB_LO = ( IO_STATE(R_TLB_LO, global,no  ) |
				      IO_STATE(R_TLB_LO, valid, no  ) |
				      IO_STATE(R_TLB_LO, kernel,no  ) |
				      IO_STATE(R_TLB_LO, we,    no  ) |
				      IO_FIELD(R_TLB_LO, pfn,   0   ) );
		}
	}
	local_irq_restore(flags);
}

/* dump the entire TLB for debug purposes */

#if 0
void
dump_tlb_all(void)
{
	int i;
	unsigned long flags;
	
	printk("TLB dump. LO is: pfn | reserved | global | valid | kernel | we  |\n");

	local_save_flags(flags);
	local_irq_disable();
	for(i = 0; i < NUM_TLB_ENTRIES; i++) {
		*R_TLB_SELECT = ( IO_FIELD(R_TLB_SELECT, index, i) );
		printk("Entry %d: HI 0x%08lx, LO 0x%08lx\n",
		       i, *R_TLB_HI, *R_TLB_LO);
	}
	local_irq_restore(flags);
}
#endif

/*
 * Initialize the context related info for a new mm_struct
 * instance.
 */

int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
	mm->context.page_id = NO_CONTEXT;
	return 0;
}

/* called in schedule() just before actually doing the switch_to */

void 
switch_mm(struct mm_struct *prev, struct mm_struct *next,
	  struct task_struct *tsk)
{
	/* make sure we have a context */

	get_mmu_context(next);

	/* remember the pgd for the fault handlers
	 * this is similar to the pgd register in some other CPU's.
	 * we need our own copy of it because current and active_mm
	 * might be invalid at points where we still need to derefer
	 * the pgd.
	 */

	current_pgd = next->pgd;

	/* switch context in the MMU */
	
	D(printk("switching mmu_context to %d (%p)\n", next->context, next));

	*R_MMU_CONTEXT = IO_FIELD(R_MMU_CONTEXT, page_id, next->context.page_id);
}